Entrapping of fullerenes, nanotubes, and inorganic nanoparticles by a DNA-chitosan complex: a method for nanomaterials removal.

PubMed

Zinchenko, Anatoly A; Maeda, Noriko; Pu, Shengyan; Murata, Shizuaki

2013-05-07

We report a protocol for entrapping of various water-dispersed nanomaterials: fullerenes, multiwall carbon nanotubes, quantum dots (semiconductor nanoparticles), and gold nanorods, into a DNA-chitosan complex. In contrast to small-size nanomaterial particles, the bulky DNA-chitosan interpolyelectrolyte complex incorporating the dispersed nanomaterials can be easily separated from aqueous media by centrifugation, filtration, or decantation. While the removal of nanoparticles by centrifugation is equally efficient for every type of nanoparticles and reaches 100%, the higher efficiency of the nanomaterials removal by other two methods is favored by larger size of nanoparticles. The application of this entrapping protocol for removal of nanomaterials from water is discussed.

Heat recirculating cooler for fluid stream pollutant removal

DOEpatents

Richards, George A.; Berry, David A.

2008-10-28

A process by which heat is removed from a reactant fluid to reach the operating temperature of a known pollutant removal method and said heat is recirculated to raise the temperature of the product fluid. The process can be utilized whenever an intermediate step reaction requires a lower reaction temperature than the prior and next steps. The benefits of a heat-recirculating cooler include the ability to use known pollutant removal methods and increased thermal efficiency of the system.

Continuous tank reactors in series: an improved alternative in the removal of phenolic compounds with immobilized peroxidase.

PubMed

Gómez, E; Máximo, M F; Montiel, M C; Gómez, M; Murcia, M D; Ortega, S

2012-01-01

Immobilized derivatives of soybean peroxidase, covalently bound to a glass support, were used in a continuous stirred tank reactor in series, in order to study the removal of two phenolic compounds: phenol and 4-chlorophenol. The use of two reactors in series, rather than one continuous tank, improved the removal efficiencies of phenol and 4-chlorophenol. The distribution of different amounts of enzyme between the two tanks showed that the relative distributions influenced the removal efficiency reached and the degree of the enzyme deactivation. The highest removal percentages were reached at the outlet of the second tank for a distribution of 50% of the enzyme in each tank. However, with a distribution of 75% in the first tank and 25% in the second, the elimination percentage in the second tank was slightly lower than in the previous case, and the effects of deactivation of the enzyme in the first tank were less pronounced. In all the distributions assayed it was observed that the first tank acts as a filter for the second one, which receives a feed with a smaller load of phenolic compounds, thus diminishing enzyme deactivation in the second tank.

Removal of H{sub 2}S, methyl macapton dimethyl sulfide and dimethyl disulfide with biofiltration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, B.; Milligan, D.

1996-12-31

A pilot study describes the biofiltration process control that was necessary to remove H{sub 2}S, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide, when mixed in an airstream. A pilot test at a waste water treatment facility was operated over a six month period. During that time H{sub 2}S was removed with very high efficiency at concentrations that reached to 400 ppm{sub v}; H{sub 2}S loading reached as high as 20 gms/m{sup 3}/hr. Methyl mercaptan and the organic sulfides were not removed sufficiently to deodorize the air-stream until a second stage biofilter was added. An odor analysis indicated that the odormore » detection level was approximately 250,000 odor units at the inlet and 1100 odor units at the outlet. The sulfur distribution in the media indicated that elemental sulfur and sulfate is deposited as a byproduct of the H{sub 2}S oxidation. Data from a fall scale biofilter treating H{sub 2}S from a pumping station is also presented. This data shows very efficient removal of H{sub 2}S, no organic reduced sulfur compounds were found in this air-stream.« less

[Characteristics and mechanism of sodium removal by the synergistic action of flue gas and waste solid].

PubMed

Yi, Yuan-Rong; Han, Min-Fang

2012-07-01

The carbon dioxide (CO2) in flue gas was used to remove the sodium in the red mud (RM) , a kind of alkaline solid waste generated during alumina production. The reaction characteristics and mechanism of sodium removal by the synergistic action of CO2 and RM were studied with different medium pH, reaction time and temperature. It was demonstrated that the remove of sodium by RM was actually the result of the synergistic action of sodium-based solid waste in RM with the CO2-H2O and OH(-)-CO2 systems. The sodium removal efficiency was correlated with pH, reaction temperature and time. The characteristics of RM before and after sodium removal were analyzed using X-ray diffractometer (XRD) and scanning electron microscope (SEM), and the results showed that the alkaline materials in the red mud reacted with CO2 and the sodium content in solid phases decreased significantly after reaction. The sodium removal efficiency could reach up to 70% with scientific procedure. The results of this research will offer an efficient way for low-cost sodium removal.

Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone.

PubMed

Kazemipour, Maryam; Ansari, Mehdi; Tajrobehkar, Shabnam; Majdzadeh, Majdeh; Kermani, Hamed Reihani

2008-01-31

In this work, adsorption of copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) that exist in industrial wastewater onto the carbon produced from nutshells of walnut, hazelnut, pistachio, almond, and apricot stone has been investigated. All the agricultural shell or stone used were ground, sieved to a defined size range, and carbonized in an oven. Time and temperature of heating were optimized at 15 min and 800 degrees C, respectively, to reach maximum removal efficiency. Removal efficiency was optimized regarding to the initial pH, flow rate, and dose of adsorbent. The maximum removal occurred at pH 6-10, flow rate of 3 mL/min, and 0.1g of the adsorbent. Capacity of carbon sources for removing cations will be considerably decreased in the following times of passing through them. Results showed that the cations studied significantly can be removed by the carbon sources. Efficiency of carbon to remove the cations from real wastewater produced by copper industries was also studied. Finding showed that not only these cations can be removed considerably by the carbon sources noted above, but also removing efficiency are much more in the real samples. These results were in adoption to those obtained by standard mixture synthetic wastewater.

Removal of Cr(VI) from Aqueous Environments Using Micelle-Clay Adsorption

PubMed Central

Qurie, Mohannad; Khamis, Mustafa; Manassra, Adnan; Ayyad, Ibrahim; Nir, Shlomo; Scrano, Laura; Bufo, Sabino A.; Karaman, Rafik

2013-01-01

Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques. PMID:24222757

[Influencing factors and mechanism of arsenic removal during the aluminum coagulation process].

PubMed

Chen, Gui-Xia; Hu, Cheng-Zhi; Zhu, Ling-Feng; Tong, Hua-Qing

2013-04-01

Aluminum coagulants are widely used in arsenic (As) removal during the drinking water treatment process. Aluminium chloride (AlCl3) and polyaluminium chloride (PACl) which contains high content of Al13 were used as coagulants. The effects of aluminum species, pH, humic acid (HA) and coexisting anions on arsenic removal were investigated. Results showed that AlCl3 and PACl were almost ineffective in As(II) removal while the As(V) removal efficiency reached almost 100%. pH was an important influencing factor on the arsenic removal efficiency, because pH influenced the distribution of aluminum species during the coagulation process. The efficiency of arsenic removal by aluminum coagulants was positively correlated with the content of Al13 species. HA and some coexisting anions showed negative impact on arsenic removal because of the competitive adsorption. The negative influence of HA was more pronounced at low coagulant dosages. PO4(3-) and F(-) showed marked influence during arsenic removal, but there was no obvious influence when SiO3(2-), CO3(2-) and SO4(2-) coexisted. The present study would be helpful to direct arsenic removal by enhanced coagulation during the drinking water treatment.

[Studies on the degradation of paracetamol in sono-electrochemical oxidation].

PubMed

Dai, Qi-Zhou; Ma, Wen-Jiao; Shen, Hong; Chen, Jun; Chen, Jian-Meng

2012-07-01

A novel lead dioxide electrodes co-doped with rare earth and polytetrafluoroethylene (PTFE) were prepared by the electrode position method and applied as anodes in sono-electrochemical oxidation for pharmaceutical wastewater degradation. The results showed that the APAP removal and the mineralization efficiency reached an obvious increase, which meant that the catalytic efficiency showed a significant improvement in the use of rare-earth doped electrode. The effects of process factors showed that the condition of the electrode had the best degradation efficiency with doped with Ce2O3 under electrolyte concentration of 14.2 g x L(-1), 49.58 W x cm(-2), 50 Hz, pH = 3, 71.43 mA x cm(-2). The APAP of 500 mg x L(-1) removal rate reached 92.20% and its COD and TOC values declined to 79.95% and 58.04%, the current efficiency reached 45.83% after degradation process for 2.0 h. The intermediates were monitored by the methods of GC-MS, HPLC, and IC. The main intermediates of APAP were p-benzoquinone, benzoic acid, acetic acid, maleic acid, oxalic acid, formic acid etc, and the final products were carbon dioxide and water. The goal of completely degradation of pollutant was achieved and a possible degradation way was proposed.

3,5-Dichlorophenol Removal From Wastewater Using Alternative Adsorbents

NASA Astrophysics Data System (ADS)

Kobetičová, Hana; Lipovský, Marek; Wachter, Igor; Soldán, Maroš

2015-06-01

The main objective of this paper is to evaluate the efficiency of 3,5-dichlorophenol removal from wastewater by using alternative low cost adsorbents. Waste from the production and processing of metals (black nickel mud, red mud) and a biosorbent (Lemna minor) were used for this research. Initial concentration of the contaminant was 4 mmol L-1, the contact time of sorbent and waste water was 0 - 48 hrs and the temperature during experiment was 25 ± 0.2 °C. The results show that the highest removal efficiency of 3,5 - dichlorophenol (58.18 %) was reached by the red mud in 48 hours.

Treatment of oilfield wastewater by combined process of micro-electrolysis, Fenton oxidation and coagulation.

PubMed

Zhang, Zhenchao

2017-12-01

In this study, a combined process was developed that included micro-electrolysis, Fenton oxidation and coagulation to treat oilfield fracturing wastewater. Micro-electrolysis and Fenton oxidation were applied to reduce chemical oxygen demand (COD) organic load and to enhance organic components gradability, respectively. Orthogonal experiment were employed to investigate the influence factors of micro-electrolysis and Fenton oxidation on COD removal efficiency. For micro-electrolysis, the optimum conditions were: pH, 3; iron-carbon dosage, 50 mg/L; mass ratio of iron-carbon, 2:3; reaction time, 60 min. For Fenton oxidation, a total reaction time of 90 min, a H 2 O 2 dosage of 12 mg/L, with a H 2 O 2 /Fe 2+ mole ratio of 30, pH of 3 were selected to achieve optimum oxidation. The optimum conditions in coagulation process: pH, cationic polyacrylamide dosage, mixing speed and time is 4.3, 2 mg/L, 150 rpm and 30 s, respectively. In the continuous treatment process under optimized conditions, the COD of oily wastewater fell 56.95%, 46.23%, 30.67%, respectively, from last stage and the total COD removal efficiency reached 83.94% (from 4,314 to 693 mg/L). In the overall treatment process under optimized conditions, the COD of oily wastewater was reduced from 4,314 to 637 mg/L, and the COD removal efficiency reached 85.23%. The contribution of each stage is 68.45% (micro-electrolysis), 24.07% (Fenton oxidation), 7.48% (coagulation), respectively. Micro-electrolysis is the uppermost influencing process on COD removal. Compared with the COD removal efficiency of three processes on raw wastewater under optimized conditions: the COD removal efficiency of single micro-electrolysis, single Fenton oxidation, single coagulation is 58.34%, 44.88% and 39.72%, respectively. Experiments proved the effect of combined process is marvelous and the overall water quality of the final effluent could meet the class III national wastewater discharge standard of petrochemical industry of China (GB8978-1996).

Environmental risk assessment of effluents as a whole emerging contaminant: Efficiency of alternative tertiary treatments for wastewater depuration.

PubMed

Díaz-Garduño, B; Pintado-Herrera, M G; Biel-Maeso, M; Rueda-Márquez, J J; Lara-Martín, P A; Perales, J A; Manzano, M A; Garrido-Pérez, C; Martín-Díaz, M L

2017-08-01

Emerging contaminants (ECs) and regulated compounds (RCs) from three different WWTP effluents were measured in the current study. The efficiency of two tertiary treatments, Photobiotreatment (PhtBio) and Multi-Barrier Treatment (MBT), for removing contaminants was determined. Results indicated different percentages of removal depending on the treatment and the origin of the effluent. Risk Quotients (RQs) were determined for different species of algae, Daphnia, and fish. RQ results revealed diverse risk values depending on the bioindicator species. Tonalide, galaxolide (fragrances), and ofloxacin (antibiotic) were the most persistent and harmful substances in tested effluents. "Negligible risk" category was reached since a wide diversity of ECs were removed by MBT with high removal percentages. Contrarily, PhtBio was effective only in the depuration of certain chemical compounds, and its efficiency depended on the composition of the raw effluent. Copyright © 2017 Elsevier Ltd. All rights reserved.

UV-catalytic treatment of spent caustic from ethene plant with hydrogen peroxide and ozone oxidation.

PubMed

Yu, Zheng-zhe; Sun, De-zhi; Li, Chang-hai; Shi, Peng-fei; Duan, Xiao-dong; Sun, Guo-rong; Liu, Jun-xin

2004-01-01

The performance of UV/H2O2, UV/O3 and UV/H2O2/O3 oxidation systems for treating spent caustic from an ethylene plant was investigated. In UV/H2O2 system, with the increase of H2O2 dosage, removal efficiencies of COD and the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the H2O2 system alone. In UV/H2O2 system, removal efficiency of COD reach 68% under the optimum condition, and BOD/COD ratio was significantly increased from 0.22 to 0.52. In UV/O3 system, with the increase of O3 dosage, removal efficiency of COD and BOD/COD ratio were increased, and a better performance was obtained than the O3 system alone. Under the optimum condition, removal efficiency of COD was 54%, and BOD/COD ratio was significantly increased from 0.22 to 0.48. In UV/H2O2/O3 system, COD removal efficiency was found to be 22.0% higher than UV/O3 system.

Effect of alkalinity on nitrite accumulation in treatment of coal chemical industry wastewater using moving bed biofilm reactor.

PubMed

Hou, Baolin; Han, Hongjun; Jia, Shengyong; Zhuang, Haifeng; Zhao, Qian; Xu, Peng

2014-05-01

Nitrogen removal via nitrite (the nitrite pathway) is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio (amount of alkalinity to ammonia ratio, mol/mol). There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient (compared to the theoretical alkalinity amount), ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria (NOB) by free ammonia (FA) in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Research on denitrification efficiency of three types of solid carbon source

NASA Astrophysics Data System (ADS)

Cai, Y.; Zhang, J. D.; Li, F.; Cao, Y. X.; Zhu, L. Y.; Xiao, M. S.

2018-01-01

C/N rates can greatly influence efficiency of denitrification. It is difficult for current treated effluent to reach GB18918-2002 primary effluent standard because of its low C/N rate. To improve the efficiency of denitrification, the quality of effluent, and realize the waste recycling, this article selected magnolia leaves, loofah and degradable meal box as the solid carbon source and set different solid-liquid ratio of magnolia leaves for periodic denitrification stage to study the change of NO3 --N, TN, COD, NO2 --N, NH4 +, PO4 3- and color. The results showed that in the condition of influent nitrate concentration of 40 mg/L, carbon dosage of 10 g, the reaction temperature of 25°C, the nitrate removal rates of magnolia leaves and loofah reached 89.0% and 96.8% respectively, rather higher than degradable meal box (56.3%). The TN removal rates of magnolia leaves (91.7%) and loofah (77.7%) were both higher than degradable meal box (53.9%), and the effluent TN concentration of loofah and degradable meal box reached 25.4 mg/L and 21.1 mg/L respectively, which couldn’t be discharged according to the primary effluent concentration standard of GB18918-2002. The released concentration of ammonia nitrogen and phosphate: loofah> magnolia> degradable meal box. The high solid-liquid ratio of magnolia leaves helped to improve the TN removal rate, which reached 75.0% (1:200) and 91.7% (1:100), but it caused higher released concentration of carbon, ammonia nitrogen and phosphate to effect system heavily. Under the integrated analysis, the low solid-liquid ratio (1:200) of magnolia leaves was more suitable to be the denitrification external carbon source.

[Study on the calcium-based sorbent for removal fluorine during coal combustion].

PubMed

Li, Shu-ling; Qi, Qing-jie; Liu, Jian-zhong; Cao, Xin-yu; Zhou, Jun-hu; Cen, Ke-fa

2004-03-01

In the paper, the reaction of CaO-HF and fluorine removal mechanics at high temperature by blending calcium-based sorbents with coal during coal combustion were discussed, and test results about fluorine retention during coal combustion in fluidized bed and chain-grate furnace were reported. The results identified that lime and calcium-based sorbets developed can restratin the emission of fluorine during coal combustion. The efficiency of fluorine removal can reach 66.7%-70.0% at Ca/F 60-70 by blending lime with coal in fluidized bed combustion, and the efficiency of fluorine removal are between 57.32% and 75.19% by blending calcium-based sorbets with coal in chain-grate furnace combustion. Blending CaO or lime with coal during coal combustion can remove SO2 and HF simultaneously.

Mastication and oral health-related quality of life in removable denture wearers with Alzheimer disease.

PubMed

Campos, Camila H; Ribeiro, Giselle R; Rodrigues Garcia, Renata C M

2018-05-01

Alzheimer disease (AD) can affect masticatory function, affecting oral health-related quality of life (OHRQoL). Whether oral rehabilitation with conventional removable prostheses can restore masticatory function and improve OHRQoL in these individuals is unknown. The purpose of this clinical study was to evaluate the influence of oral rehabilitation with removable prostheses on masticatory efficiency and OHRQoL in elders with and without AD. Thirty-two elders with mild AD (n=16, mean age=76.7 ±6.3 years) or without AD (n=16, mean age=75.2 ±4.4 years) were recruited. All participants first underwent masticatory efficiency and OHRQoL evaluations, and 2 months after insertion of new removable prostheses, the variables were reassessed. Masticatory efficiency was determined using the sieving method, and OHRQoL was measured by applying the Geriatric Oral Health Assessment Index (GOHAI). The data from the baseline and after insertion of the new removable prostheses were compared by paired t test. Group differences at each time point were assessed by t test (α=.05). After insertion of the new removable prostheses, masticatory efficiency and OHRQoL improved in both the elders with AD and the control. At baseline, elders with AD had lower masticatory efficiency and higher OHRQoL than controls (P<.05). After removable prosthesis insertion, elders with AD continued to show lower masticatory efficiency values than controls, but their OHRQoL was similar. Oral rehabilitation with new removable prostheses improved the masticatory efficiency and OHRQoL of elders with and without AD, although masticatory efficiency did not reach control levels in elders with AD. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Selective Fenton-like oxidation of methylene blue on modified Fe-zeolites prepared via molecular imprinting technique.

PubMed

Zhang, Yuanyuan; Shang, Jiaobo; Song, Yanqun; Rong, Chuan; Wang, Yinghui; Huang, Wenyu; Yu, Kefu

2017-02-01

A facile strategy to increase the selectivity of heterogeneous Fenton oxidation is investigated. The increase was reached by increasing selective adsorption of heterogeneous Fenton catalyst to a target pollutant. The heterogeneous Fenton catalyst was prepared by a two-step process. First, zeolite particles were imprinted by the target pollutant, methylene blue (MB), in their aggregations, and second, iron ions were loaded on the zeolite aggregations to form the molecule imprinted Fe-zeolites (MI-FZ) Fenton catalyst. Its adsorption amount for MB reached as high as 44.6 mg g -1 while the adsorption amount of un-imprinted Fe-zeolites (FZ) is only 15.6 mg g -1 . Fenton removal efficiency of MI-FZ for MB was 87.7%, being 33.9% higher than that of FZ. The selective Fenton oxidation of MI-FZ for MB was further confirmed by its removal performance for the mixed MB and bisphenol A (BPA) in solution. The removal efficiency of MB was 44.7% while that of BPA was only 14.9%. This fact shows that molecular imprinting is suitable to prepare the Fe-zeolites (FZ)-based Fenton catalyst with high selectivity for removal of target pollutants, at least MB.

Nitrogen Removal Characteristics of a Newly Isolated Indigenous Aerobic Denitrifier from Oligotrophic Drinking Water Reservoir, Zoogloea sp. N299.

PubMed

Huang, Ting-Lin; Zhou, Shi-Lei; Zhang, Hai-Han; Bai, Shi-Yuan; He, Xiu-Xiu; Yang, Xiao

2015-05-04

Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA). Its specific growth rate was 0.22 h-1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53%±1.69% and 58.65%±0.61%, respectively. The ammonia removal rate reached 44.12%±1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5-9 mg/L, pH 8-9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41%±3.17% (sterilized) and 44.88%±4.31% (unsterilized). The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p<0.05). High C/N was beneficial for nitrate reduction (p<0.05). The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p>0.05). Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem.

Effects of iron and calcium carbonate on contaminant removal efficiencies and microbial communities in integrated wastewater treatment systems.

PubMed

Zhao, Zhimiao; Song, Xinshan; Zhang, Yinjiang; Zhao, Yufeng; Wang, Bodi; Wang, Yuhui

2017-12-01

In the paper, we explored the influences of different dosages of iron and calcium carbonate on contaminant removal efficiencies and microbial communities in algal ponds combined with constructed wetlands. After 1-year operation of treatment systems, based on the high-throughput pyrosequencing analysis of microbial communities, the optimal operating conditions were obtained as follows: the ACW10 system with Fe 3+ (5.6 mg L -1 ), iron powder (2.8 mg L -1 ), and CaCO 3 powder (0.2 mg L -1 ) in influent as the adjusting agents, initial phosphorus source (PO 4 3- ) in influent, the ratio of nitrogen to phosphorus (N/P) of 30 in influent, and hydraulic retention time (HRT) of 1 day. Total nitrogen (TN) removal efficiency and total phosphorus (TP) removal efficiency were improved significantly. The hydrolysis of CaCO 3 promoted the physicochemical precipitation in contaminant removal. Meanwhile, Fe 3+ and iron powder produced Fe 2+ , which improved contaminant removal. Iron ion improved the diversity, distribution, and metabolic functions of microbial communities in integrated treatment systems. In the treatment ACW10, the dominant phylum in the microbial community was PLANCTOMYCETES, which positively promoted nitrogen removal. After 5 consecutive treatments in ACW10, contaminant removal efficiencies for TN and TP respectively reached 80.6% and 57.3% and total iron concentration in effluent was 0.042 mg L -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

[Effect of UV Light Radiation on the Coagulation of Chlorella and Its Mechanism].

PubMed

Wang, Wen-dong; Zhang, Ke; Xu, Hong-bin; Liu, Guo-qi

2016-01-15

Considering algae were difficult to be effectively removed in conventional water treatment process, UV radiation was used to enhance the coagulation of algae in this study. The results showed that with the increase of radiation time, the removal rates of both algae and turbidity experienced a decrease after an increase, and reached their maximum values at 50 min. When the dosage of PAC was 5 mg x L(-1), the removal rates of algae and turbidity of the radiated sample were 20.1% and 18% higher than the blank sample, respectively. When pH ranged from 6 to 9, the coagulation efficiency varied little. At pH 8 and with a radiation time of 50 min, the removal rates of algae and turbidity reached 93.5% and 90.6%, respectively. Meanwhile, the Zeta potential reached the maximum, and the algae generated extracellular organic matter, which favored the subsequent coagulation. After radiated for 60 min, the algal cells was destroyed, leading to a release of intracellular organic matter into the solution. Accordingly, the Zeta potential decreased, which had a negative effect on the subsequent coagulation process.

Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization.

PubMed

Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

2015-09-23

Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO₃(-)-N, less into NO₂(-)-N, not into N₂.

Conversion Characteristics and Production Evaluation of Styrene/o-Xylene Mixtures Removed by DBD Pretreatment

PubMed Central

Jiang, Liying; Zhu, Runye; Mao, Yubo; Chen, Jianmeng; Zhang, Liang

2015-01-01

The combination of chemical oxidation methods with biotechnology to removal recalcitrant VOCs is a promising technology. In this paper, the aim was to identify the role of key process parameters and biodegradability of the degradation products using a dielectric barrier discharge (DBD) reactor, which provided the fundamental data to evaluate the possibilities of the combined system. Effects of various technologic parameters like initial concentration of mixtures, residence time and relative humidity on the decomposition and the degradation products were examined and discussed. It was found that the removal efficiency of mixed VOCs decreased with increasing initial concentration. The removal efficiency reached the maximum value as relative humidity was approximately 40%–60%. Increasing the residence time resulted in increasing the removal efficiency and the order of destruction efficiency of VOCs followed the order styrene > o-xylene. Compared with the single compounds, the removal efficiency of styrene and o-xylene in the mixtures of VOCs decreased significantly and o-xylene decreased more rapidly. The degradation products were analyzed by gas chromatography and gas chromatography-mass spectrometry, and the main compounds detected were O3, COx and benzene ring derivatives. The biodegradability of mixed VOCs was improved and the products had positive effect on biomass during plasma application, and furthermore typical results indicated that the biodegradability and biotoxicity of gaseous pollutant were quite depending on the specific input energy (SIE). PMID:25629961

Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea.

PubMed

Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Qin, Guangyong

2017-03-30

As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE) technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

Highly efficient removal of pathogenic bacteria with magnetic graphene composite.

PubMed

Zhan, Sihui; Zhu, Dandan; Ma, Shuanglong; Yu, Wenchao; Jia, Yanan; Li, Yi; Yu, Hongbing; Shen, Zhiqiang

2015-02-25

Magnetic Fe3O4/graphene composite (abbreviated as G-Fe3O4) was synthesized successfully by solvothermal method to effectively remove both bacteriophage and bacteria in water, which was tested by HRTEM, XRD, BET, XPS, FTIR, CV, magnetic property and zeta-potential measurements. Based on the result of HRTEM, the single-sheet structure of graphene oxide and the monodisperse Fe3O4 nanoparticles on the surface of graphene can be observed obviously. The G-Fe3O4 composite were attractive for removing a wide range of pathogens including not only bacteriophage ms2, but also various bacteria such as S. aureus, E. coli, Salmonella, E. Faecium, E. faecalis, and Shigella. The removal efficiency of E. coli for G-Fe3O4 composite can achieve 93.09%, whereas it is only 54.97% with pure Fe3O4 nanoparticles. Moreover, a detailed verification test of real water samples was conducted and the removal efficiency of bacteria in real water samples with G-Fe3O4 composite can also reach 94.8%.

Nitrate removal and microbial analysis by combined micro-electrolysis and autotrophic denitrification.

PubMed

Xing, Wei; Li, Desheng; Li, Jinlong; Hu, Qianyi; Deng, Shihai

2016-07-01

A process combining micro-electrolysis and autotrophic denitrification (CEAD) with iron-carbon micro-electrolysis carriers was developed for nitrate removal. The process was performed using organic-free influent with a NO3(-)-N concentration of 40.0±3.0mg/L and provided an average nitrate removal efficiency of 95% in stable stages. The total nitrogen removal efficiency reached 75%, with 21% of NO3(-)-N converted into NH4(+)-N. The corresponding hydraulic retention time was 8-10h, and the optimal pH ranged from 8.5 to 9.5. Microbial analysis with high-throughput sequencing revealed that dominant microorganisms in the reactor belonged to the classes of β-, γ-, and α-Proteobacteria. The abundance of the genera Thermomonas significantly increased during the operation, comprising 21.4% and 24.1% in sludge attached to the carriers in the middle and at the bottom of the reactor, respectively. The developed CEAD achieved efficient nitrate removal from water without organics, which is suitable for practical application. Copyright © 2016. Published by Elsevier Ltd.

Performance of hybrid constructed wetland systems for treating septic tank effluent.

PubMed

Cui, Li-hua; Liu, Wen; Zhu, Xi-zhen; Ma, Mei; Huang, Xi-hua; Xia, Yan-yang

2006-01-01

The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time (HRT) was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD (chemical oxygen demand) were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 (5 d biochemical oxygen demand) removal rate in four seasons. The average removal rates of TP (total phosphorous) could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN (total nitrogen) was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality from the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells (hybrid systems) showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.

Sustainability of a constructed wetland faced with a depredation event.

PubMed

Maine, M A; Hadad, H R; Sánchez, G C; Mufarrege, M M; Di Luca, G A; Caffaratti, S E; Pedro, M C

2013-10-15

A free water surface constructed wetland (CW) designed for effluent treatment was dominated by the emergent macrophyte Typha domingensis reaching a cover of roughly 80% for 5 years. Highly efficient metal and nutrient removal was reported during this period. In June 2009, a population of approximately 30 capybaras (Hydrochoerus hydrochaeris) caused the complete depredation of the aerial parts of macrophytes. However, plant roots and rhizomes were not damaged. After depredation stopped, T. domingensis showed a luxuriant growth, reaching a cover of 60% in 30 days. The objective of this work was to evaluate the sustainability of the CW subjected to an extreme event. Removal efficiency of the system was compared during normal operation, during the depredation event and over the subsequent recovery period. The CW efficiently retained contaminants during all the periods studied. However, the best efficiencies were registered during the normal operation period. There were no significant differences between the performances of the CW over the last two periods, except for BOD. The mean removal percentages during normal operation/depredation event/recovery period, were: 84.9/73.2/74.7% Cr; 66.7/48.0/51.2% Ni; 97.2/91.0/89.4% Fe; 50.0/46.8/49.5% Zn; 81.0/84.0/80.4% NO3(-); 98.4/93.4/84.1% NO2(-); 73.9/28.2/53.2% BOD and 75.4/40.9/44.6% COD. SRP and TP presented low removal efficiencies. Despite the anoxic conditions, contaminants were not released from sediment, accumulating in fractions that proved to be stable faced with changes in the operating conditions of the CW. T. domingensis showed an excellent growth response, consequently the period without aerial parts lasted a few months and the CW could recover its normal operation. Plants continued retaining contaminants in their roots and the sediment increased its retention capacity, balancing the operating capacity of the system. This was probably due to the fact that the CW had reached its maturity, with a complete root-rhizome development. These results demonstrated that faced with an incidental problem, this mature CW was capable of maintaining its efficiency and recovering its vegetation, demonstrating the robustness of these treatment systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

Combined ultrasound and Fenton (US-Fenton) process for the treatment of ammunition wastewater.

PubMed

Li, Yangang; Hsieh, Wen-Pin; Mahmudov, Rovshan; Wei, Xiaomei; Huang, C P

2013-01-15

A wastewater collected from a regional ammunition process site was treated with combined US-Fenton process. Factors such as pH, temperature, reaction time, US energy intensity, initial TOC concentration, and the molar ratio of iron to hydrogen peroxide that might affect the treatment efficiency were investigated. The removal of TOC, COD, and color increased with decreasing pH and increasing temperature and US intensity. Color was removed rapidly reaching 85% in 10 min; whereas TOC and COD were removed slowly, only about 20% for both in 10 min and approaching 65 and 92% removal in 120 min, respectively. The optimal molar ratio of Fe(II) to H(2)O(2) for TOC and COD removal was 500. The results showed that the change in the average carbon oxidation number (ACON) was parallel to that of the removal efficiency of TOC, COD, and color. The toxicity of treated wastewater was reduced as assessed by the respiration rate of Escherichia coli. Copyright © 2013 Elsevier B.V. All rights reserved.

A preliminary study on the occurrence and dissipation of estrogen in livestock wastewater.

PubMed

Tang, Xianjin; Naveedullah; Hashmi, Muhammad Zaffar; Zhang, Hu; Qian, Mingrong; Yu, Chunna; Shen, Chaofeng; Qin, Zhihui; Huang, Ronglang; Qiao, Jiani; Chen, Yingxu

2013-04-01

Livestock wastewater has high estrogen activity because animal excreta contain estrogen. In the past, when biological technologies were applied to treat livestock wastewater, the removal efficiency of estrogen pollutants was always ignored. Therefore, the efficiency of estrogen removal by anaerobic/aerobic (A/O) treatment and by up flow anaerobic sludge blanket and step-fed sequencing batch reactor (UASB-SFSBR) treatment was investigated in the present study. The results showed that the A/O treatment had no significant estrogenic removal ability, whereas the removal rates of estrogen after UASB-SFSBR treatment reached approximately 78 %, as measured by liquid chromatography and tandem mass spectrometry. The estrogen concentration decreased from 31.5 ng/L to an undetectable level according to the yeast estrogen screen analysis. We found differences between the estrogen removal rates measured by the chemical assay and those measured using the bioassay. More attention must be paid to the removal of estrogen pollutants in livestock wastewater to reduce the environmental risk.

Simultaneous removal of NO and SO2 using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS).

PubMed

Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Jun

2018-01-01

Simultaneous removal process of SO 2 and NO from flue gas using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS) in a VUV spraying reactor was proposed. The key influencing factors, active species, reaction products and mechanism of SO 2 and NO simultaneous removal were investigated. The results show that vacuum ultraviolet light (185 nm) achieves the highest NO removal efficiency and yield of and under the same test conditions. NO removal is enhanced at higher PMS concentration, light intensity and oxygen concentration, and is inhibited at higher NO concentration, SO 2 concentration and solution pH. Solution temperature has a double impact on NO removal. CO 2 concentration has no obvious effect on NO removal. and produced from VUV-activation of PMS play a leading role in NO removal. O 3 and ·O produced from VUV-activation of O 2 also play an important role in NO removal. SO 2 achieves complete removal under all experimental conditions due to its very high solubility in water and good reactivity. The highest simultaneous removal efficiency of SO 2 and NO reaches 100% and 91.3%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Identification and Nitrogen Removal Characteristics of a Heterotrophic Nitrification-Aerobic Denitrification Strain Isolated from Marine Environment].

PubMed

Sun, Qing-hua; Yu, De-shuang; Zhang, Pei-yu; Lin, Xue-zheng; Li, Jin

2016-02-15

A heterotrophic nitrification-aerobic denitrification strain named y5 was isolated from marine environment by traditional microbial isolation method using seawater as medium. It was identified as Klebsiella sp. based on the morphological, physiological and 16S rRNA sequence analysis. The experiment results showed that the optimal carbon resource was sodium citrate; the optimal pH was 7.0; and the optimal C/N was 17. The strain could use NH4Cl, NaNO2 and KNO3 as sole nitrogen source, and the removal efficiencies were77.07%, 64.14% and 100% after 36 hours, respectively. The removal efficiency reached 100% after 36 hours in the coexistence of NH4Cl, NaNO2 and KNO3. The results showed that the strain y5 had independent and efficient heterotrophic nitrification and aerobic denitrification activities in high salt wastewater.

Biosorption studies on copper (II) and cadmium (II) using pretreated rice straw and rice husk.

PubMed

Li, W C; Law, F Y; Chan, Y H M

2017-04-01

This study investigated the adsorption and removal behaviour of copper (Cu) (II) and cadmium (Cd) (II) ions using rice husk and rice straw in aqueous solutions. Different parameters were used to investigate their adsorption performance in saline conditions and the optimal level of biosorption at different pH levels. The main parameters were pH (3, 6 and 9), initial concentration level of heavy metals (Cu (II) 5, 10, 20, 40 and 60 mg/L and Cd (II) 0.5, 1, 2, 4 and 8 mg/L, respectively), salinity (0, 50 and 100 mM NaCl) and contact time (ranging from 3 to 60 min). Langmuir and Freundlich isotherm models were applied to analyse the removal efficiency and sorption capacity of the pretreated rice husk and rice straw. The removal efficiency and adsorption capacity generally increased with the pH and reached a plateau in alkaline conditions. The percentage removal of Cu (II) by rice husk reached 97 % at pH 9 and 95 % by rice straw at pH 6. Biosorption performance increased in the absence of NaCl. Kinetic studies for both metals revealed that the biosorption of Cu (II) and Cd (II) onto rice straw and husk was pseudo-second order.

Study on the removal of iron impurities in methanesulfonic acid tin plating bath

NASA Astrophysics Data System (ADS)

Hou-li, LIU; Jian-Jun, CHEN; Hong-Liang, PAN

2018-03-01

This thesis investigated the the influence of sodium sulfite as reducing agent on the recovery rate of tin ion. The approach is that HZ016 type cation exchange resin was used to adsorb Sn2+ and Fe2+ in electroplated tin solution first. After adsorption, the resin was removed by sulfuric acid, which was added with NaOH to adjust pH value to form precipitation and separate tin. X-ray diffraction (XRD) and energy spectrum (EDS) method were used to analyze the composition of the precipitates adjusted by pH. The results show that when the mass ratio of resin to bath is 1:2, the adsorption efficiency of resin reaches 98.3% and 97.1% respectively, and the elution efficiency of tin and iron reaches 95.1% and 94% respectively when the mass ratio of resin to eluent sulfuric acid is 1:4. Sodium sulfite was added to increase the efficiency of tin recovery by 8.1%. EDS and XRD atlas showed that after pH regulation, the main composition of the filtration precipitation was the hydroxides of tin.

Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes

USGS Publications Warehouse

Alexander, Richard B.; Böhlke, John Karl; Boyer, Elizabeth W.; David, Mark B.; Harvey, Judson W.; Mulholland, Patrick J.; Seitzinger, Sybil P.; Tobias, Craig R.; Tonitto, Christina; Wollheim, Wilfred M.

2009-01-01

The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction of nitrogen in streamflow is removed to the atmosphere via denitrification with the remainder exported in streamflow as nitrogen loads. At the watershed scale, there is a keen interest in understanding the factors that control the fate of nitrogen throughout the stream channel network, with particular attention to the processes that deliver large nitrogen loads to sensitive coastal ecosystems. We use a dynamic stream transport model to assess biogeochemical (nitrate loadings, concentration, temperature) and hydrological (discharge, depth, velocity) effects on reach-scale denitrification and nitrate removal in the river networks of two watersheds having widely differing levels of nitrate enrichment but nearly identical discharges. Stream denitrification is estimated by regression as a nonlinear function of nitrate concentration, streamflow, and temperature, using more than 300 published measurements from a variety of US streams. These relations are used in the stream transport model to characterize nitrate dynamics related to denitrification at a monthly time scale in the stream reaches of the two watersheds. Results indicate that the nitrate removal efficiency of streams, as measured by the percentage of the stream nitrate flux removed via denitrification per unit length of channel, is appreciably reduced during months with high discharge and nitrate flux and increases during months of low-discharge and flux. Biogeochemical factors, including land use, nitrate inputs, and stream concentrations, are a major control on reach-scale denitrification, evidenced by the disproportionately lower nitrate removal efficiency in streams of the highly nitrate-enriched watershed as compared with that in similarly sized streams in the less nitrate-enriched watershed. Sensitivity analyses reveal that these important biogeochemical factors and physical hydrological factors contribute nearly equally to seasonal and stream-size related variations in the percentage of the stream nitrate flux removed in each watershed.

[Interactive effect of spent mushroom compost and rhamnolipids to enhance the efficiency of alfalfa remediation of aged PAHs contaminated soil].

PubMed

Zhang, Jing; Lin, Xian-Gui; Li, Xuan-Zhen; Yin, Rui

2010-10-01

Polycyclic aromatic hydrocarbons (PAHs) are a group of the most widespread organic pollutants, which distributed widely in soil and sediment. Pot experiment was conducted to improve efficiency of phytoremediation using alfalfa (Medicago sativa L.) in aged PAHs contaminated soil by introducing spent mushroom compost and rhamnolipids. Plant biomass, PAHs concentrations, number of soil microorganism, soil enzyme activity and soil microbial functional diversity were determined after 60 days of alfalfa growth. The results showed that within 60 days, removal ratio of PAHs in treatment of alfalfa alone (AL) reached to 14.43%, while removal ratio of PAHs in treatments of "GZ + RH0.5, + AL" and "GZ + RH1.0 + AL" reached to 32.64% and 36.95%, which were 115.45% and 156.06% higher than that of phytoremediation. Contrasted to the control, the treatment of "GZ + RH1.0 + AL" had more plant biomass than others, shoot and root dry weight were 1.05 g/pot and 0.20 g/pot, respectively. During the process of phytoremediation, the number of soil bacteria and fungi were greatly increased by "GZ + RH1.0 + AL" and reached to 31.37 x 10(6) CFU x g(-1) and 5.86 x 10(6) CFU x g(-1), especially the number of PAHs-degrading bacteria reached to 39.57 x 10(5) MPN x g(-1), which were 29 times more than control treatment and 4 times more than treatment of alfalfa alone (AL). Moreover, soil dehydrogenase activity and the functional diversity of soil microbial community were increased significantly by the treatment of "GZ + RH1.0 + AL", respectively. Therefore, interaction of spent mushroom compost and rhamnolipids to enhance the phytoremediation efficiency had satisfied results in removal aged PAHs from an agricultural soil, the feasibility of this method needed to be further proved by large-area scale field experiment.

Integrated removal of NO and mercury from coal combustion flue gas using manganese oxides supported on TiO2.

PubMed

Zhang, Shibo; Zhao, Yongchun; Wang, Zonghua; Zhang, Junying; Wang, Lulu; Zheng, Chuguang

2017-03-01

A catalyst composed of manganese oxides supported on titania (MnO x /TiO 2 ) synthesized by a sol-gel method was selected to remove nitric oxide and mercury jointly at a relatively low temperature in simulated flue gas from coal-fired power plants. The physico-chemical characteristics of catalysts were investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses, etc. The effects of Mn loading, reaction temperature and individual flue gas components on denitration and Hg 0 removal were examined. The results indicated that the optimal Mn/Ti molar ratio was 0.8 and the best working temperature was 240°C for NO conversion. O 2 and a proper ratio of [NH 3 ]/[NO] are essential for the denitration reaction. Both NO conversion and Hg 0 removal efficiency could reach more than 80% when NO and Hg 0 were removed simultaneously using Mn0.8Ti at 240°C. Hg 0 removal efficiency slightly declined as the Mn content increased in the catalysts. The reaction temperature had no significant effect on Hg 0 removal efficiency. O 2 and HCl had a promotional effect on Hg 0 removal. SO 2 and NH 3 were observed to weaken Hg 0 removal because of competitive adsorption. NO first facilitated Hg 0 removal and then had an inhibiting effect as NO concentration increased without O 2 , and it exhibited weak inhibition of Hg 0 removal efficiency in the presence of O 2 . The oxidation of Hg 0 on MnO x /TiO 2 follows the Mars-Maessen and Langmuir-Hinshelwood mechanisms. Copyright © 2016. Published by Elsevier B.V.

Determination of pharmaceutical compounds in hospital wastewater and their elimination by advanced oxidation processes.

PubMed

Souza, Fernanda S; Da Silva, Vanessa V; Rosin, Catiusa K; Hainzenreder, Luana; Arenzon, Alexandre; Pizzolato, Tania; Jank, Louise; Féris, Liliana A

2018-02-23

This study investigates the mineralization efficiency, i.e. removal of total organic carbon (TOC) in hospital wastewater by direct ozonation, ozonation with UV radiation (O 3 /UV), homogeneous catalytic ozonation (O 3 /Fe 2+ ) and homogeneous photocatalytic ozonation (O 3 /Fe 2+ /UV). The influence of pH and reaction time was evaluated. For the best process, toxicity and degradation efficiency of the selected pharmaceutical compounds (PhCs) were determined. The results showed that the PhCs detected in the hospital wastewater were completely degraded when the mineralization efficiency reached 54.7% for O 3 /UV with 120 minutes of reaction time using a rate of 1.57 g O 3 h -1 . This process also achieved a higher chemical oxygen demand removal efficiency (64.05%), an increased aromaticity reduction efficiency (81%) and a toxicity reduction.

Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel

NASA Astrophysics Data System (ADS)

Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

2017-02-01

The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

Nitrogen Removal Characteristics of a Newly Isolated Indigenous Aerobic Denitrifier from Oligotrophic Drinking Water Reservoir, Zoogloea sp. N299

PubMed Central

Huang, Ting-Lin; Zhou, Shi-Lei; Zhang, Hai-Han; Bai, Shi-Yuan; He, Xiu-Xiu; Yang, Xiao

2015-01-01

Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA). Its specific growth rate was 0.22 h−1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53% ± 1.69% and 58.65% ± 0.61%, respectively. The ammonia removal rate reached 44.12% ± 1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5–9 mg/L, pH 8–9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41% ± 3.17% (sterilized) and 44.88% ± 4.31% (unsterilized). The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p < 0.05). High C/N was beneficial for nitrate reduction (p < 0.05). The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p > 0.05). Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem. PMID:25946341

Continuous energy recovery and nutrients removal from molasses wastewater by synergistic system of dark fermentation and algal culture under various fermentation types.

PubMed

Ren, Hong-Yu; Kong, Fanying; Ma, Jun; Zhao, Lei; Xie, Guo-Jun; Xing, Defeng; Guo, Wan-Qian; Liu, Bing-Feng; Ren, Nan-Qi

2018-03-01

Synergistic system of dark fermentation and algal culture was initially operated at batch mode to investigate the energy production and nutrients removal from molasses wastewater in butyrate-type, ethanol-type and propionate-type fermentations. Butyrate-type fermentation was the most appropriate fermentation type for the synergistic system and exhibited the accumulative hydrogen volume of 658.3 mL L -1 and hydrogen yield of 131.7 mL g -1 COD. By-products from dark fermentation (mainly acetate and butyrate) were further used to cultivate oleaginous microalgae. The maximum algal biomass and lipid content reached 1.01 g L -1 and 38.5%, respectively. In continuous operation, the synergistic system was stable and efficient, and energy production increased from 8.77 kJ L -1  d -1 (dark fermentation) to 17.3 kJ L -1  d -1 (synergistic system). Total COD, TN and TP removal efficiencies in the synergistic system reached 91.1%, 89.1% and 85.7%, respectively. This study shows the potential of the synergistic system in energy recovery and wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Treatment of wastewater containing o-phenylenediamine by ozone in a rotor-stator reactor.

PubMed

Arowo, Moses; Li, Yingwen; Chu, Guangwen; Sun, Baochang; Chen, Jianfeng; Shao, Lei

2016-01-01

This work employed a novel rotor-stator reactor (RSR) to intensify the degradation process of o-phenylenediamine (o-PDA) by ozone. The effects of different operating parameters including initial pH, temperature, rotation speed, liquid volumetric flow rate and inlet ozone concentration on the removal efficiency of o-PDA were investigated in an attempt to establish the optimum conditions. The removal efficiency was evaluated in terms of degradation ratio and chemical oxygen demand (COD) reduction ratio of the o-PDA wastewater. Results indicate that the removal efficiency decreased with increasing liquid volumetric flow rate but increased with an increase in pH and inlet ozone concentration. Also, the removal efficiency increased up to a certain level with an increase in rotation speed and temperature. Additionally, a comparison experiment was carried out in a stirred tank reactor (STR), and the results show that the degradation and COD reduction ratios reached a maximum of 94.6% and 61.2% in the RSR as compared to 45.3% and 28.6% in the STR, respectively. This work demonstrates that ozone oxidation carried out in RSR may be a promising alternative for pre-treatment of o-PDA wastewater.

Advanced treatment of biologically pretreated coal chemical industry wastewater using the catalytic ozonation process combined with a gas-liquid-solid internal circulating fluidized bed reactor.

PubMed

Li, Zhipeng; Liu, Feng; You, Hong; Ding, Yi; Yao, Jie; Jin, Chao

2018-04-01

This paper investigated the performance of the combined system of catalytic ozonation and the gas-liquid-solid internal circulating fluidized bed reactor for the advanced treatment of biologically pretreated coal chemical industry wastewater (CCIW). The results indicated that with ozonation alone for 60min, the removal efficiency of chemical oxygen demand (COD) could reach 34%. The introduction of activated carbon, pumice, γ-Al 2 O 3 carriers improved the removal performance of COD, and the removal efficiency was increased by 8.6%, 4.2%, 2%, respectively. Supported with Mn, the catalytic performance of activated carbon and γ-Al 2 O 3 were improved significantly with COD removal efficiencies of 46.5% and 41.3%, respectively; however, the promotion effect of pumice supported with Mn was insignificant. Activated carbon supported with Mn had the best catalytic performance. The catalytic ozonation combined system of MnO X /activated carbon could keep ozone concentration at a lower level in the liquid phase, and promote the transfer of ozone from the gas phase to the liquid phase to improve ozonation efficiency.

[Treatment of wastewater containing Cr(VI) by LDH synthesizing in situ].

PubMed

Chen, Tian-hu; Feng, You-liang; Xu, Hui-fang; Peng, Shu-chuan; Huang, Chuan-hui; Tang, Shu-pei

2004-03-01

The objective of this work was to investigate the efficiency and factors impacting of removal Cr(VI) from wastewater by layer double hydroxide synthesizing in situ. Principle of the method may be described as follow: Mg2+ and Al3+ hydrolysis and forms Mg/Al-LDH by adding Mg2+, Al3+ and NaOH into wastewater containing Cr(VI), Cr(VI) anions are selectively intercalated into interlayer of LDH to balance positive structural charge. While Mg2+ and Al3+ co-precipitates and forms LDH, the Cr(VI) in wastewater is removal by settle of LDH synthesizing in situ, which are confirmed by analysis of X-ray diffraction on settle and chemical analysis on aqueous. The results indicate that factors of impacting on efficiency of removal Cr(VI) include in amount of adding Mg2+ and Al3+, Mg/Al ratio, pH and concentration of Cr(VI) in wastewater. The maximal removal efficiency of Cr(VI) can be reached when pH values are between 8.5 and 9, and Mg/Al ratios are between 1:1 and 2:1, meanwhile, Mg and Al added can be taken good use of. This technology has present extraordinary efficiency of wastewater treatment.

Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization

PubMed Central

Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

2015-01-01

Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO3−-N, less into NO2−-N, not into N2. PMID:26404353

Methyl-orange and cadmium simultaneous removal using fly ash and photo-Fenton systems.

PubMed

Visa, Maria; Duta, Anca

2013-01-15

Wastewaters resulting from the textile and dye finishing industries need complex treatment for efficient removal of colour and other compounds existent in the dyeing and rising baths (heavy metals, surfactants, equalizers, etc.). Modified fly ash (FA) mixed with TiO(2) photocatalyst represent a viable option for simultaneous removal of dyes and heavy metals, and the optimized conditions are discussed in this paper for synthetic wastewaters containing methyl-orange (MO) and cadmium. For a cost-effective dye removal process, further tests were done, replacing the photocatalyst with a (photo)Fenton system. The optimized technological parameters (contact time, amount of fly ash and amount of Fe(2+)/H(2)O(2)) allow to reach removal efficiencies up to 88% for the heavy metal and up to 70% for the dye. The adsorption mechanisms and the process kinetic are discussed, also considering the possibility of in situ generation of the Fenton system, due to the fly ash composition. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob.

PubMed

Wang, Xuming; Xing, Lijun; Qiu, Tianlei; Han, Meilin

2013-04-01

Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98% and 40-45% when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91% of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.

Test of precoat filtration technology for treatment of swimming pool water.

PubMed

Christensen, Morten Lykkegaard; Klausen, Morten Møller; Christensen, Peter Vittrup

2018-02-01

The technical performance of a precoat filter was compared with that of a traditional sand filter. Particle concentration and size distribution were measured before and after the filtration of swimming pool water. Both the sand and precoat filters could reduce the particle concentration in the effluent. However, higher particle removal efficiency was generally observed for the precoat filter, especially for particles smaller than 10 μm in diameter. Adding flocculant improved the removal efficiency of the sand filter, resulting in removal efficiencies comparable to those of the precoat filter. Three powders, i.e., two types of perlite (Harbolite ® and Aquatec perlite) and cellulose fibers (Arbocel ® ), were tested for the precoat filter, but no significant difference in particle removal efficiency was observed among them. The maximum efficiency was reached within 30-40 min of filtration. The energy required for the pumps increased by approximately 35% over a period of 14 days. The energy consumption could be reduced by replacing the powder on the filter cloth. The sand filter was backwashed once a week, while the powder on the precoat filter was replaced every two weeks. Under these conditions, it was possible to reduce the water used for cleaning by 88% if the precoat filter was used instead of the sand filter.

Mesophilic and thermophilic biotreatment of BTEX-polluted air in reactors.

PubMed

Mohammad, Balsam T; Veiga, María C; Kennes, Christian

2007-08-15

This study compares the removal of a mixture of benzene, toluene, ethylbenzene, and all three xylene isomers (BTEX) in mesophilic and thermophilic (50 degrees C) bioreactors. In the mesophilic reactor fungi became dominant after long-term operation, while bacteria dominated in the thermophilic unit. Microbial acclimation was achieved by exposing the biofilters to initial BTEX loads of 2-15 g m(-3) h(-1), at an empty bed residence time of 96 s. After adaptation, the elimination capacities ranged from 3 to 188 g m(-3) h(-1), depending on the inlet load, for the mesophilic biofilter with removal efficiencies reaching 96%. On the other hand, in the thermophilic reactor the average removal efficiency was 83% with a maximum elimination capacity of 218 g m(-3) h(-1). There was a clear positive relationship between temperature gradients as well as CO(2) production and elimination capacities across the biofilters. The gas phase was sampled at different depths along the reactors observing that the percentage pollutant removal in each section was strongly dependant on the load applied. The fate of individual alkylbenzene compounds was checked, showing the unusually high biodegradation rate of benzene at high loads under thermophilic conditions (100%) compared to its very low removal in the mesophilic reactor at such load (<10%). Such difference was less pronounced for the other pollutants. After 210 days of operation, the dry biomass content for the mesophilic and thermophilic reactors were 0.300 and 0.114 g g(-1) (support), respectively, reaching higher removals under thermophilic conditions with a lower biomass accumulation, that is, lower pressure drop. (c) 2007 Wiley Periodicals, Inc.

Experimental study on removal of NO using adsorption of activated carbon/reduction decomposition of microwave heating.

PubMed

Shuang-Chen, Ma; Yao, Juan-Juan; Gao, Li

2012-01-01

Experimental studies were carried out on flue gas denitrification using activated carbon irradiated by microwave. The effects of microwave irradiation power (reaction temperature), the flow rate of flue gas, the concentration of NO and the flue gas coexisting compositions on the adsorption property of activated carbon and denitrification efficiency were investigated. The results show that: the higher of microwave power, the higher of denitrification efficiency; denitrification efficiency would be greater than 99% and adsorption capacity of NO is relatively stable after seven times regeneration if the microwave power is more than 420 W; adsorption capacity of NO in activated carbon bed is 33.24 mg/g when the space velocity reaches 980 per hour; adsorption capacity declines with increasing of the flow rate of flue gas; the change in denitrification efficiency is not obvious with increasing oxygen content in the flue gas; and the maximum adsorption capacity of NO was observed when moisture in flue gas was about 5.88%. However, the removal efficiency of NO reduces with increasing moisture, and adsorption capacity and removal efficiency of NO reduce with increasing of SO2 concentration in the flue gas.

The utilization of waste by-products for removing silicate from mineral processing wastewater via chemical precipitation.

PubMed

Kang, Jianhua; Sun, Wei; Hu, Yuehua; Gao, Zhiyong; Liu, Runqing; Zhang, Qingpeng; Liu, Hang; Meng, Xiangsong

2017-11-15

This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater. Chemical precipitation is used to remove silicate from scheelite (CaWO 4 ) cleaning flotation wastewater and the waste by-products are used as a substitute for calcium chloride (CaCl 2 ). A series of laboratory experiments is conducted to explain the removal of silicate and the characterization and formation mechanism of calcium silicate. The results show that silicate removal reaches 90% when the Ca:Si molar ratio exceeds 1.0. The X-ray diffraction (XRD) results confirm the characterization and formation of calcium silicate. The pH is the key factor for silicate removal, and the formation of polysilicic acid with a reduction of pH can effectively improve the silicate removal and reduce the usage of calcium. The economic analysis shows that the treatment costs with waste acid (0.63 $/m 3 ) and waste alkali (1.54 $/m 3 ) are lower than that of calcium chloride (2.38 $/m 3 ). The efficient removal of silicate is confirmed by industrial testing at a plant. The results show that silicate removal reaches 85% in the recycled water from tailings dam. Copyright © 2017 Elsevier Ltd. All rights reserved.

Growing Chlorella sp. on meat processing wastewater for nutrient removal and biomass production.

PubMed

Lu, Qian; Zhou, Wenguang; Min, Min; Ma, Xiaochen; Chandra, Ceria; Doan, Yen T T; Ma, Yiwei; Zheng, Hongli; Cheng, Sibo; Griffith, Richard; Chen, Paul; Chen, Chi; Urriola, Pedro E; Shurson, Gerald C; Gislerød, Hans R; Ruan, Roger

2015-12-01

In this work, Chlorella sp. (UM6151) was selected to treat meat processing wastewater for nutrient removal and biomass production. To balance the nutrient profile and improve biomass yield at low cost, an innovative algae cultivation model based on wastewater mixing was developed. The result showed that biomass yield (0.675-1.538 g/L) of algae grown on mixed wastewater was much higher than that on individual wastewater and artificial medium. Wastewater mixing eased the bottleneck for algae growth and contributed to the improved biomass yield. Furthermore, in mixed wastewater with sufficient nitrogen, ammonia nitrogen removal efficiencies (68.75-90.38%) and total nitrogen removal efficiencies (30.06-50.94%) were improved. Wastewater mixing also promoted the synthesis of protein in algal cells. Protein content of algae growing on mixed wastewater reached 60.87-68.65%, which is much higher than that of traditional protein source. Algae cultivation model based on wastewater mixing is an efficient and economical way to improve biomass yield. Copyright © 2015 Elsevier Ltd. All rights reserved.

Removal of mercury (II), elemental mercury and arsenic from simulated flue gas by ammonium sulphide.

PubMed

Ning, Ping; Guo, Xiaolong; Wang, Xueqian; Wang, Ping; Ma, Yixing; Lan, Yi

2015-01-01

A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg(2+), Hg(0) and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg(2+), Hg(0) and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas.

Evaluation of BTEX and phenol removal from aqueous solution by multi-solute adsorption onto smectite organoclay.

PubMed

Carvalho, M N; da Motta, M; Benachour, M; Sales, D C S; Abreu, C A M

2012-11-15

The removal process of BTEX and phenol was evaluated. The smectite organoclay for single-solute system reached removal was evaluated by adsorption on smectite organoclay adsorbent by kinetic and equilibrium efficiencies between 55 and 90% while was reached between 30 and 90% for multi-solute system at 297 K and pH 9. The Langmuir-Freundlich model was used to fit the experimental data with correlation coefficient between 0.98 and 0.99 providing kinetic and equilibrium parameter values. Phenol and ethylbenzene presented high maximum adsorbed amount, 8.28 and 6.67 mg/g, respectively, compared to the other compounds for single-solute. Toluene and p-xylene presented high values of adsorption constant which indicates a high adsorption affinity of compounds to organoclay surface and high binding energy of adsorption. Phenol presented low kinetic adsorption constant value indicating slow rate of adsorption. Copyright © 2012 Elsevier B.V. All rights reserved.

[Screening and ammoxidation characteristics of an ammonium oxidizing bacteria group].

PubMed

Yang, Xiaolong; Liu, Lihua; Wu, Bingqi; Liu, Shujie; Chen, Fuming

2015-12-04

This study aimed to screen high-performance ammonia oxidizing bacteria ( AOB) resistant to a high concentration of ammonia-nitrogen and low C/N ratio, for the development of novel AOB agents. Multi-point sampling, compulsory domestication, gradient dilution of domestication liquid were conducted to screen AOB with efficient and stable ammonia-nitrogen removing ability, and effects of different factors on its ammoxidation ability including C/N ratio, shaking speed and ammonia-nitrogen concentration were studied. Dominant strains were screened and identified by morphological observation, physiological and biochemical properties test and 16S rRNA sequence analysis. Three efficient AOB were obtained, among them a micro-flora named JQ8 showed the highest activity. The ammonia-nitrogen removal rate reached 95. 07% in a simulated wastewater with 17. 86 mmol/L of initial ammonia-nitrogen at C/N 4 treated by JQ8 for 6 days. Moreover, its ammonia nitrogen removal rate kept above 95% and net nitrogen removing rate nearly 80% in the solution with a C/N ratio above 4 and an NH₄⁺-N concentration below 28.57 mmol/L. The circuit board industry wastewater was treated using the laboratory-simulated aerobic active sludge disposal system. The removal rate of NH₄⁺-N and total nitrogen reached 87.8% and 67.6% respectively after 7 days' treatment using JQ8. Defluvibacter sp., Paracoccus sp. and Aquamicrobium sp. were identified as the dominant strains after the composition analysis of JQ8. An ammonia oxidizing bacteria consortium JQ8 screened from the landfill leachate showed a strong ammonium-nitrogen removal and endurance ability under low C/N ratio and high ammonia-nitrogen concentration, thus is probably applicable to intensify the ammonia-nitrogen removal treatment of industrial wastewater with sewage disposal system.

Removal efficiency and enzymatic mechanism of dibutyl phthalate (DBP) by constructed wetlands.

PubMed

Qi, Xin; Li, Tiancui; Wang, Feihua; Dai, Yanran; Liang, Wei

2018-06-01

Four vertical-flow constructed wetland systems were set up in the field in order to study the removal efficiency and possible enzymatic mechanism of the constructed wetlands in treating sewage containing different concentrations of dibutyl phthalate (DBP). Under DBP spiked concentrations of 0.5, 1.0, and 2.0 mg/L, good DBP removal rates of 62.08, 82.17, and 84.17% were achieved, respectively. Meanwhile, certain removal effects of general water quality parameters were observed in all four constructed wetlands: with high average removal rates of nitrate nitrogen (NO 3 - -N) and chemical oxygen demand (COD) of 91.10~93.89 and 82.83~89.17%, respectively, with moderate removal efficiencies of total nitrogen (TN), total phosphorus (TP), ammonia nitrogen (NH 4 + -N) of 44.59~49.67, 30.58~37.18, and 28.52~37.45%, respectively. Compared to the control, an increase of enzyme activities of urease, phosphatase, dehydrogenase, and nitrate reductase was observed in the treatments with DBP addition. In the presence of 0.5 mg/L of DBP concentration, the urease, phosphatase, and dehydrogenase activities reached the highest levels, with an increase of 350.02, 36.57, and 417.88% compared with the control, respectively. It appeared that the low concentration of DBP might better stimulate the release of enzymes.

Removing Organic Matter and Nutrients from Pig Farm Wastewater with a Constructed Wetland System

PubMed Central

De La Mora-Orozco, Celia; González-Acuña, Irma Julieta; Saucedo-Terán, Ruben Alfonso; Flores-López, Hugo Ernesto; Rubio-Arias, Hector Osbaldo; Ochoa-Rivero, Jesús Manuel

2018-01-01

Pollutants from pig farms in Mexico have caused problems in many surface water reservoirs. Growing concern has driven the search for low-cost wastewater treatment solutions. The objective of this research was to evaluate the potential of an in-series constructed wetland to remove nutrients from wastewater from a pig farm. The wetland system had a horizontal flow that consisted of three cells, the first a surface water wetland, the second a sedimentation cell, and the third a subsurface flow wetland. The vegetation used was Thypa sp. and Scirpus sp. A mix of soil with red volcanic rock (10–30 mm diameter) and yellow sand (2–8 mm diameter) was used as a substrate for the vegetation. The experiments were carried out in duplicate. Water samples were collected at the inflow and outflow of the cells. Two hydraulic retention times (HRT) (5 and 10 days) and three treatments were evaluated: 400, 800, and 1200 mg·L−1 of chemical oxygen demand (COD) concentration. Data was collected in situ for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). COD, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3–N), and total phosphorous (TP) were analyzed in the laboratory. The results showed that the in-series constructed wetland is a feasible system for nutrient pollutant removal, with COD removal efficiency of 76% and 80% mg·L−1 for a 5- and 10-day HRT, respectively. The removal efficiency for TKN, NH3–N, and TP reached about 70% with a 5-day HRT, while a removal of 85% was obtained with a 10-day HRT. The wetland reached the maximum removal efficiency with a 10-day HRT and an inflow load of 400 mg·L−1 of organic matter. The results indicate that HRT positively affects removal efficiency of COD and TDS. On the other hand, the HRT was not the determining factor for TP removal. Treatment one, with an initial COD concentration of 400 mg·L−1, had the highest removal of the assessed pollutants, allowing for the use of water for irrigation according to Mexican regulatory standards (NOM-001). The water quality resulting from treatments two and three (T2 = 800 mg·L−1 of COD and T3 = 1200 mg·L−1 of COD) did not comply with minimal requirements for irrigation water. PMID:29883370

Biosorption of Arsenic(III) from Aqueous Solutions by Modified Fungal Biomass of Paecilomyces sp.

PubMed Central

Acosta Rodríguez, Ismael; Martínez-Juárez, Víctor M.; Cárdenas-González, Juan F.; Moctezuma-Zárate, María de Guadalupe

2013-01-01

The biosorption of As(III) on iron-coated fungal biomass of Paecilomyces sp. was studied in this work. It was found that the biomass was very efficient removing the metal in solution, using Atomic Absorption, reaching the next percentage of removals: 64.5%. The highest adsorption was obtained at pH 6.0, at 30°C after 24 hours of incubation, with 1 mg/L of modified fungal biomass. PMID:24235911

Dynamic study of Cr(VI) removal performance and mechanism from water using multilayer material coated nanoscale zerovalent iron.

PubMed

Wu, Bin; Peng, Dinghua; Hou, Siyu; Tang, Bicong; Wang, Can; Xu, Heng

2018-05-16

In this study, the dynamic Cr(VI) removal process from water by the synthesized multilayer material coated nanoscale zerovalent iron (SBC-nZVI) was systematically discussed at different treatment conditions. The results showed that initial pH, contact time, Cr(VI) concentration and the dosage of SBC-nZVI were important parameters that influenced the Cr(VI) removal efficiency. The major Cr(VI) removal occurred within 60 min and gradually tend to equilibrium with consistent treatment. The removal efficiency was highly depended on pH values and the adsorption kinetics agreed well with the pseduo-second-order model (PSO). When the initial Cr(VI) concentration was below 15 mg/L, the removal rate could reach to about 100%. Moreover, the removal efficiency increased with the increase of SBC-nZVI dosage, which related to the increase of reactive sites. To understand the removal mechanism, SBC-nZVI before and after reaction with Cr(VI) were characterized by fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). These analysis showed that the interaction of SBC-nZVI with Cr(VI) was mainly controlled by reduction and electrostatic attraction. Therefore, these results explained the interaction between Cr(VI) and SBC-nZVI material in detail, and further proved that SBC-nZVI could be an effective material to remove Cr(VI) from water. Copyright © 2018. Published by Elsevier Ltd.

Comparative study on metal biosorption by two macroalgae in saline waters: single and ternary systems.

PubMed

Figueira, Paula; Henriques, Bruno; Teixeira, Ana; Lopes, Cláudia B; Reis, Ana T; Monteiro, Rui J R; Duarte, A C; Pardal, M A; Pereira, E

2016-06-01

The biosorption capability of two marine macroalgae (green Ulva lactuca and brown Fucus vesiculosus) was evaluated in the removal of toxic metals (Hg, Cd and Pb) from saline waters, under realistic conditions. Results showed that, independently of the contamination scenario tested, both macroalgae have a remarkable capacity to biosorb Hg and Pb. In single-contaminant systems, by using only c.a. 500 mg of non-pre-treated algae biomass (size <200 μm) per litter, it was possible to achieve removal efficiencies between 96 and 99 % for Hg and up to 86 % for Pb. Despite the higher removal of Hg, equilibrium was reached more quickly for Pb (after 8 h). In multi-contaminant systems, macroalgae exhibited a similar selectivity toward the target metals: Hg > Pb> > Cd, although Pb removal by U. lactuca was more inhibited than that achieved by F. vesiculosus. Under the experimental conditions used, none of the macroalgae was effective to remove Cd (maximum removal of 20 %). In all cases, the kinetics of biosorption was mathematically described with success. Globally, it became clear that the studied macroalgae may be part of simple, efficient, and cost-effective water treatment technologies. Nevertheless, Fucus vesiculosus has greater potential, since it always presented higher initial sorption rates and higher removal efficiencies.

Evaluation of soil pH and moisture content on in-situ ozonation of pyrene in soils.

PubMed

Luster-Teasley, S; Ubaka-Blackmoore, N; Masten, S J

2009-08-15

In this study, pyrene spiked soil (300 ppm) was ozonated at pH levels of 2, 6, and 8 and three moisture contents. It was found that soil pH and moisture content impacted the effectiveness of PAH oxidation in unsaturated soils. In air-dried soils, as pH increased, removal increased, such that pyrene removal efficiencies at pH 6 and pH 8 reached 95-97% at a dose of 2.22 mg O(3)/mg pyrene. Ozonation at 16.2+/-0.45 mg O(3)/ppm pyrene in soil resulted in 81-98% removal of pyrene at all pH levels tested. Saturated soils were tested at dry, 5% or 10% moisture conditions. The removal of pyrene was slower in moisturized soils, with the efficiency decreasing as the moisture content increased. Increasing the pH of the soil having a moisture content of 5% resulted in improved pyrene removals. On the contrary, in the soil having a moisture content of 10%, as the pH increased, pyrene removal decreased. Contaminated PAH soils were stored for 6 months to compare the efficiency of PAH removal in freshly contaminated soil and aged soils. PAH adsorption to soil was found to increase with longer exposure times; thus requiring much higher doses of ozone to effectively oxidize pyrene.

Evaluation of mercury speciation and removal through air pollution control devices of a 190 MW boiler.

PubMed

Wu, Chengli; Cao, Yan; Dong, Zhongbing; Cheng, Chinmin; Li, Hanxu; Pan, Weiping

2010-01-01

Air pollution control devices (APCDs) are installed at coal-fired power plants for air pollutant regulation. Selective catalytic reduction (SCR) and wet flue gas desulfurization (FGD) systems have the co-benefits of air pollutant and mercury removal. Configuration and operational conditions of APCDs and mercury speciation affect mercury removal efficiently at coal-fired utilities. The Ontario Hydro Method (OHM) recommended by the U.S. Environmental Protection Agency (EPA) was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit. Chlorine in coal had been suggested as a factor affecting the mercury speciation in flue gas; and low-chlorine coal was purported to produce less oxidized mercury (Hg2+) and more elemental mercury (Hg0) at the SCR inlet compared to higher chlorine coal. SCR could oxidize elemental mercury into oxidized mercury when SCR was in service, and oxidation efficiency reached 71.0%. Therefore, oxidized mercury removal efficiency was enhanced through a wet FGD system. In the non-ozone season, about 89.5%-96.8% of oxidized mercury was controlled, but only 54.9%-68.8% of the total mercury was captured through wet FGD. Oxidized mercury removal efficiency was 95.9%-98.0%, and there was a big difference in the total mercury removal efficiencies from 78.0% to 90.2% in the ozone season. Mercury mass balance was evaluated to validate reliability of OHM testing data, and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.

Treatment of synthetic wastewater and hog waste with reduced sludge generation by the multi-environment BioCAST technology.

PubMed

Yerushalmi, L; Alimahmoodi, M; Mulligan, C N

2013-01-01

Simultaneous removal of carbon, nitrogen and phosphorus was examined along with reduced generation of biological sludge during the treatment of synthetic wastewater and hog waste by the BioCAST technology. This new multi-environment wastewater treatment technology contains both suspended and immobilized microorganisms, and benefits from the presence of aerobic, microaerophilic, anoxic and anaerobic conditions for the biological treatment of wastewater. The influent concentrations during the treatment of synthetic wastewater were 1,300-4,000 mg chemical oxygen demand (COD)/L, 42-115 mg total nitrogen (TN)/L, and 19-40 mg total phosphorus (TP)/L. The removal efficiencies reached 98.9, 98.3 and 94.1%, respectively, for carbon, TN and TP during 225 days of operation. The removal efficiencies of carbon and nitrogen showed a minimal dependence on the nitrogen-to-phosphorus (N/P) ratio, while the phosphorus removal efficiency showed a remarkable dependence on this parameter, increasing from 45 to 94.1% upon the increase of N/P ratio from 3 to 4.5. The increase of TN loading rate had a minimal impact on COD removal rate which remained around 1.7 kg/m(3) d, while it contributed to increased TP removal efficiency. The treatment of hog waste with influent COD, TN and TP concentrations of 960-2,400, 143-235 and 25-57 mg/L, respectively, produced removal efficiencies up to 89.2, 69.2 and 47.6% for the three contaminants, despite the inhibitory effects of this waste towards biological activity. The treatment system produced low biomass yields with average values of 3.7 and 8.2% during the treatment of synthetic wastewater and hog waste, respectively.

Removal of traces of toluene and p-xylene in indoor air using biofiltration and a hybrid system (biofiltration + adsorption).

PubMed

Luengas, Angela Tatiana; Hort, Cécile; Platel, Vincent; Elias, Ana; Barona, Astrid; Moynault, Laurent

2017-04-01

Biofiltration technology and the hybrid system combining biofiltration and adsorption (onto activated carbon) were compared as possible methods to toluene and p-xylene at parts per million concentration levels (2-45 and 1-33 ppb, respectively). An organic material was used as packing material for the biofiltration process. Even at low empty bed residence times (EBRTs) and concentrations, toluene removal efficiency reached 100% and p-xylene showed an increasing trend on their removal efficiency over the time using biofiltration. The assessment of by-products and particle generation by the biofilter and the hybrid system were taken into account. Acetone and acetic acid were identified as by-products of the biofilter. Particle emissions in the range of 0.03 to 10 μm were recorded for both systems.

Technological Culture and Human Communication.

ERIC Educational Resources Information Center

Carney, John J., Jr.

Children need to develop skills enabling them to respond to television efficiently, analytically, and with discrimination. Removing children's advertising from television will not help them to understand the nature of the appeals used by the advertiser, who will find other means of reaching children; and advocating no violence on television brings…

To Remove or Not to Remove? The Challenge of Extracting the Template to Make the Cavities Available in Molecularly Imprinted Polymers (MIPs)

PubMed Central

Lorenzo, Rosa A.; Carro, Antonia M.; Alvarez-Lorenzo, Carmen; Concheiro, Angel

2011-01-01

Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods. PMID:21845081

To remove or not to remove? The challenge of extracting the template to make the cavities available in Molecularly Imprinted Polymers (MIPs).

PubMed

Lorenzo, Rosa A; Carro, Antonia M; Alvarez-Lorenzo, Carmen; Concheiro, Angel

2011-01-01

Template removal is a critical step in the preparation of most molecularly imprinted polymers (MIPs). The polymer network itself and the affinity of the imprinted cavities for the template make its removal hard. If there are remaining template molecules in the MIPs, less cavities will be available for rebinding, which decreases efficiency. Furthermore, if template bleeding occurs during analytical applications, errors will arise. Despite the relevance to the MIPs performance, template removal has received scarce attention and is currently the least cost-effective step of the MIP development. Attempts to reach complete template removal may involve the use of too drastic conditions in conventional extraction techniques, resulting in the damage or the collapse of the imprinted cavities. Advances in the extraction techniques in the last decade may provide optimized tools. The aim of this review is to analyze the available data on the efficiency of diverse extraction techniques for template removal, paying attention not only to the removal yield but also to MIPs performance. Such an analysis is expected to be useful for opening a way to rational approaches for template removal (minimizing the costs of solvents and time) instead of the current trial-and-error methods.

Remediation of Ni(2+)-contaminated water using iron powder and steel manufacturing byproducts.

PubMed

Jin, Jian; Zhao, Wei-Rong; Xu, Xin-Hua; Hao, Zhi-Wei; Liu, Yong; He, Ping; Zhou, Mi

2006-01-01

Steel manufacturing byproducts and commercial iron powders were tested in the treatment of Ni(2+)-contaminated water. Ni2+ is a priority pollutant of some soils and groundwater. The use of zero-valent iron, which can reduce Ni2+ to its neural form appears to be an alternative approach for the remediation of Ni(2+)-contaminated sites. Our experimental data show that the removal efficiencies of Ni2+ were 95.15% and 94.68% at a metal to solution ratio of 20 g/L for commercial iron powders and the steel manufacturing byproducts in 60 min at room temperature, respectively. The removal efficiency reached 98.20% when the metal to solution ratio was 40 g/L for commercial iron powders. Furthermore, we found that the removal efficiency was also largely affected by other factors such as the pHs of the treated water, the length of time for the metal to be in contact with the Ni(2+)-contaminated water, initial concentrations of metal solutions, particle sizes and the amount of iron powders. Surprisingly, the reaction temperature appeared to have little effect on the removal efficiency. Our study opens the way to further optimize the reaction conditions of in situ remediation of Ni2+ or other heavy metals on contaminated sites.

Aging of biomixtures: Effects on carbofuran removal and microbial community structure.

PubMed

Castro-Gutiérrez, Víctor; Masís-Mora, Mario; Diez, María Cristina; Tortella, Gonzalo R; Rodríguez-Rodríguez, Carlos E

2017-02-01

The aim of this work was to determine the efficiency of a straw/compost/soil biomixture for pesticide depuration during its aging and continuous use, for a period of over a year, based on its capacity to remove carbofuran (CFN), while simultaneously monitoring the variations in microbial community structure. Successive CFN spikings were applied in the biomixture at 6-week intervals, and the removal efficiency was determined 48 h post-application. Initially, only a discrete degradation performance was observed (9.9%), but one CFN application was sufficient to induce efficient elimination (>88.5%) of the pesticide at subsequent influxes for a period of over 6 months. A statistically significant reduction on CFN removal efficiency after this time was detected, reaching levels similar to the fresh-prepared biomixture (14.8%) at the end of the experiment. Simultaneous DGGE analyses showed only modest changes on microbial community patterns through time for both, bacteria and fungi. The clustering of genetic fingerprints in chronological groups corresponding to significantly different CFN degradation efficiencies indicates that biomixture aging changes not only the composition of microbial communities, but also their suitability to engage in pesticide degradation. Periodic substitution of straw/compost/soil biomixture in biopurification systems or regular provision of easily-degradable organic substrates should be considered to maintain an adequate depuration capacity on this system. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous removal of SO2 and trace SeO2 from flue gas: effect of SO2 on selenium capture and kinetics study.

PubMed

Li, Yuzhong; Tong, Huiling; Zhuo, Yuqun; Wang, Shujuan; Xu, Xuchang

2006-12-15

Sulfur dioxide (SO2) and trace elements are all pollutants derived from coal combustion. This study relates to the simultaneous removal of SO2 and trace selenium dioxide (SeO2) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range, especially the effect of SO2 presence on selenium capture. Experiments performed on a thermogravimetric analyzer (TGA) can reach the following conclusions. When the CaO conversion is relatively low and the reaction rate is controlled by chemical kinetics, the SO2 presence does not affect the selenium capture. When the CaO conversion is very high and the reaction rate is controlled by product layer diffusion, the SO2 presence and the product layer diffusion resistance jointly reduce the selenium capture. On the basis of the kinetics study, a method to estimate the trace selenium removal efficiency using kinetic parameters and the sulfur removal efficiency is developed.

Performance of the subsurface flow constructed wetlands for pretreatment of slightly polluted source water.

PubMed

Yang, Xu; Zhang, Xueping; Wang, Jifu; Zhao, Guangying; Wang, Baojian

2014-05-01

The slightly polluted source water of Yellow River was pretreated in a horizontal subsurface flow constructed wetland (HSFCW) and a lateral subsurface flow constructed wetland (LSFCW) in the Ji'nan city Reservoir, Shandong, China. During almost one years run, the results showed that at the hydraulic loading rate of 1 m/day, the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), ammonium nitrogen (NH4 (+)-N) and total phosphorus (TP) in the HSFCW were 48.9, 51.4, 48.7 and 48.9 %, respectively, and the corresponding removal efficiencies in the LSFCW were 50.51, 53.12, 50.44 and 50.83 %, respectively. The HSFCW and LSFCW had a similar high potential for nutrients removal and LSFCW was slightly better. According to the China standard for surface water resources (GB3838-2002), mean effluent COD can reach the Class I (≤ 15 mg/L), and NH4 (+)-N and TP and TN can reach nearly the Class I (≤ 0.015 mg/L), the Class III (≤ 0.05 mg/L) and the Class IV (≤ 1.5 mg/L), respectively. It can be concluded that the slightly polluted source water from Reservoir was pretreated well by the constructed wetland.

[Pilot-scale cultivation of Spirulina plantensis with digested piggery wastewater ].

PubMed

Guo, Qing-qing; Liu, Rui; Luo, Jin-fei; Wang, Gen-rong; Chen, Lii-jun; Liu, Xiao

2014-09-01

The swine waste pretreated with coagulation sedimentation was used for the outdoor pilot-scale cultivation of Spirulina platensis isolated from digested piggery wastewater (DPW) in a raceway pond. The growth of S. platensis and removal of nitrogen/ phosphorus were studied, moreover, the conversion efficiency of total nitrogen (TN) or total phosphorus (TP) from DPW to S. platensis was calculated. On this basis, the existing problems and countermeasures during outdoor pilot-scale culture were analyzed and summarized combined with the laboratory research. We conducted 6 batches culture experiments, only 3 of which could reach the S. platensis harvest requirements (D560 >0. 8). Meanwhile, the 3 successful batches achieved removal of COD, ammonia nitrogen, TN, TP with corresponding 28. 6% -48. 5% , 0.4% -48. 5% , 41. 8% -48. 6% , 14. 3% -94. 5% , and the conversion efficiency of TN or TP from DPW to S. platensis reached 12. 1% -98. 5% , 21.2% -83.7% , respectively. High concentration of ammonia nitrogen and insect attack of remaining egg hatching in the pretreated swine waste were the main factors to cause the slow-growing of the 3 batches of S. platensis. Therefore, it is highly necessary for the removal of ammonia nitrogen with biological treatment technology and insect eggs with membrane to achieve a stable high productivity.

Simultaneous electricity production and antibiotics removal by microbial fuel cells.

PubMed

Zhou, Ying; Zhu, Nengwu; Guo, Wenying; Wang, Yun; Huang, Xixian; Wu, Pingxiao; Dang, Zhi; Zhang, Xiaoping; Xian, Jinchan

2018-07-01

The removal of antibiotics is crucial for improvement of water quality in animal wastewater treatment. In this paper, the performance of microbial fuel cell (MFC) in terms of degradation of typical antibiotics was investigated. Electricity was successfully produced by using sludge supernatant mixtures and synthesized animal wastewater as inoculation in MFC. Results demonstrated that the stable voltage, the maximum power density and internal resistance of anaerobic self-electrolysis (ASE) -112 and ASE-116 without antibiotics addition were 0.574 V, 5.78 W m -3 and 28.06 Ω, and 0.565 V, 5.82 W m -3 and 29.38 Ω, respectively. Moreover, when adding aureomycin, sulfadimidine, roxithromycin and norfloxacin into the reactors, the performance of MFC was inhibited (0.51 V-0.41 V), while the output voltage was improved with the decreased concentration of antibiotics. However, the removal efficiency of ammonia nitrogen (NH 3 -N) and total phosphorus (TP) were both obviously enhanced. Simultaneously, LC-MS analysis showed that the removal efficiency of aureomycin, roxithromycin and norfloxacin were all 100% and the removal efficiency of sulfadimidine also reached 99.9%. These results indicated that antibiotics displayed significantly inhibitions for electricity performance but improved the quality of water simultaneously. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pd/RGO modified carbon felt cathode for electro-Fenton removing of EDTA-Ni.

PubMed

Zhang, Zhen; Zhang, Junya; Ye, Xiaokun; Hu, Yongyou; Chen, Yuancai

Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel due to its strong chelation. The electro-Fenton (EF) process using a cathode made from palladium (Pd), reduced graphene oxide (RGO) and carbon felt, fed with air, exhibited high activities and stability for the removal of 10 mg L(-1) EDTA-Ni solution. Pd/RGO catalyst was prepared by one-pot synthesis; the scanning electron microscopy and X-ray diffraction analysis indicated nanoparticles and RGO were well distributed on carbon felt, forming three dimensional architecture with both large macropores and a mesoporous structure. The cyclic voltammetric results showed that the presence of RGO in Pd/RGO/carbon felt significantly increased the current response of two-electron reduction of O2 (0.45 V). The key factors influencing the removal efficiency of EDTA-Ni, such as pH, current and Fe(2+) concentration, were investigated. Under the optimum conditions, the removal efficiency of EDTA-Ni reached 83.8% after 100 min EF treatment. Mechanism analysis indicated that the introduction of RGO in Pd/RGO/carbon felt significantly enhanced the electrocatalytic activities by inducing •OH in the EF process; direct H2O2 oxidation still accounted for a large amount of EDTA-Ni removal efficiency.

Biological removal of air loaded with a hydrogen sulfide and ammonia mixture.

PubMed

Chen, Ying-xu; Yin, Jun; Fang, Shi

2004-01-01

The nuisance impact of air pollutant emissions from wastewater pumping stations is a major issue of concern to China. Hydrogen sulfide and ammonia are commonly the primary odor and are important targets for removal. An alternative control technology, biofiltration, was studied. The aim of this study is to investigate the potential of unit systems packed with compost in terms of ammonia and hydrogen sulfide emissions treatment, and to establish optimal operating conditions for a full-scale conceptual design. The laboratory scale biofilter packed with compost was continuously supplied with hydrogen sulfide and ammonia gas mixtures. A volumetric load of less than 150 gH2S/(m3 x d) and 230 gNH3/(m3 x d) was applied for about fifteen weeks. Hydrogen sulfide and ammonia elimination occurred in the biofilter simultaneously. The removal efficiency, removal capacity and removal kinetics in the biofilter were studied. The hydrogen sulfide removal efficiency reached was very high above 99%, and ammonia removal efficiency was about 80%. Hydrogen sulfide was oxidized into sulphate. The ammonia oxidation products were nitrite and nitrate. Ammonia in the biofilter was mainly removed by adsorption onto the carrier material and by absorption into the water fraction of the carrier material. High percentages of hydrogen sulfide or ammonia were oxidized in the first section of the column. Through kinetics analysis, the presence of ammonia did not hinder the hydrogen sulfide removal. According to the relationship between pressure drop and gas velocity for the biofilter and Reynolds number, non-Darcy flow can be assumed to represent the flow in the medium.

Comparison between a moving bed membrane bioreactor and a conventional membrane bioreactor on organic carbon and nitrogen removal.

PubMed

Yang, Shuai; Yang, Fenglin; Fu, Zhimin; Lei, Ruibo

2009-04-01

A membrane bioreactor filled with carriers instead of activated sludge named a moving bed membrane bioreactor (MBMBR) was investigated for simultaneously removing organic carbon and nitrogen in wastewater. Its performance was compared with a conventional membrane bioreactor (CMBR) at various influent COD/TN ratios of 8.9-22.1. The operational parameters were optimized to increase the treatment efficiency. COD removal efficiency averaged at 95.6% and 96.2%, respectively, for MBMBR and CMBR during the 4 months experimental period. The MBMBR system demonstrated good performance on nitrogen removal at different COD/TN ratios. When COD/TN was 8.9 and the total nitrogen (TN) load was 7.58 mg/l h, the TN and ammonium nitrogen removal efficiencies of the MBMBR were maintained over 70.0% and 80.0%, respectively, and the removed total nitrogen (TN) load reached to 5.31 mg/l h. Multifunctional microbial reactions in the carrier, such as simultaneous nitrification and denitrification (SND), play important roles in nitrogen removal. In comparison, the CMBR did not perform so well. Its TN removal was not stable, and the removed total nitrogen (TN) load was only 1.02 mg/l h at COD/TN ratio 8.9. The specific oxygen utilization rate (SOUR) showed that the biofilm has a better microbial activity than an activated sludge. Nevertheless, the membrane fouling behavior was more severe in the MBMBR than in the CMBR due to a thick and dense cake layer formed on the membrane surface, which was speculated to be caused by the filamentous bacteria in the MBMBR.

Aerobic and heterotrophic nitrogen removal by Enterobacter cloacae CF-S27 with efficient utilization of hydroxylamine.

PubMed

Padhi, Soumesh Kumar; Tripathy, Swetaleena; Mohanty, Sriprakash; Maiti, Nikhil Kumar

2017-05-01

Heterotrophic bacterium, Enterobacter cloacae CF-S27 exhibited simultaneous nitrification and aerobic denitrification in presence of high concentration of hydroxylamine. With the initial nitrogen concentration of 100mgL -1 h -1 , ammonium, nitrate and nitrite removal efficiencies were 81%, 99.9% and 92.8%, while the corresponding maximum removal rates reached as high as 11.6, 15.1 and 11.2mgL -1 h -1 respectively. Quantitative amplification by real time PCR and enzyme assay demonstrated that hydroxylamine reductase gene (hao) is actively involved in hetrotrophic nitrification and aerobic denitrification process of Enterobacter cloacae CF-S27. PCR primers were designed targeting amplification of hao gene from diversified environmental soil DNA. The strain Enterobacter cloacae CF-S27 significantly maintained the undetectable amount of dissolved nitrogen throughout 60days of zero water exchange fish culture experiment in domestic wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microwave drying remediation of petroleum-contaminated drill cuttings.

PubMed

Júnior, Irineu Petri; Martins, André Leibsohn; Ataíde, Carlos H; Duarte, Cláudio R

2017-07-01

The oil reservoir drilling phase generates contaminated cuttings with oil formation itself. These cuttings must be subjected to a decontamination process before being disposed of in the environment. Several technologies are cited in literature for the remediation of soil contaminated with oil or diesel, but none have been reported to remedy drill cuttings contaminated with oil from reservoir. The reservoir drill cuttings are a problem because its discharge is not allowed. The drying technology using microwave has shown promise in the decontamination of cuttings with non-aqueous base drilling fluid, conciliating good robustness and high removal efficiency. Considering the aspects mentioned previously, the application of heating and drying technology using microwave in the remediation of oil contaminated cuttings from well drill was studied. The influence of temperature, specific energy and initial content of water in the drying operation of the reservoir cuttings and of the drilling cuttings artificially contaminated with oil were analyzed. The results showed an influence of temperature in the drying of the cuttings, being necessary to reach the boiling temperature of heavier hydrocarbons to reach an efficient removal in the operation. The specific energy has a strong influence, reaching a total decontamination using 2.67 kWh/kg. The initial water content was effective in removing oil, reducing the residual level of oil with the increase of initial content of water. It also modifies the temperature profiles of the kinetic-warming of the contaminated cuttings. Both the technology and the equipment used proved effective for obtaining total decontamination of oil from the cuttings. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of an attached growth reactor for NH₄-N removal at a drinking water supply system in Kathmandu Valley, Nepal.

PubMed

Khanitchaidecha, Wilawan; Shakya, Maneesha; Nakano, Yuichi; Tanaka, Yasuhiro; Kazama, Futaba

2012-01-01

Higher concentrations of ammonium (NH(4)-N) and iron (Fe) than a standard for drinking are typical characteristics of groundwater in the study area. To remove NH(4)-N and Fe, the drinking water supply system in this study consists of a series of treatment units (i.e., aeration and sedimentation, filtration, and chlorination); however, NH(4)-N in treated water is higher than a standard for drinking (i.e., <1.5 mg NH(4)-N/L). The objective of this study, therefore, is to develop an attached growth system containing a fiber carrier for reducing NH(4)-N concentration within a safe level in the treated water. To avoid the need of air supply for nitrification, groundwater was continuously dripped through the reactor. It made the system simple operation and energy efficient. Effects of reactor design (reactor length and carrier area) were studied to achieve a high NH(4)-N removal efficiency. In accordance with raw groundwater characteristics in the area, effects of low inorganic carbon (IC) and phosphate (PO(4)-P) and high Fe on the removal efficiency were also investigated. The results showed a significant increase in NH(4)-N removal efficiency with reactor length and carrier area. A low IC and PO(4)-P had no effect on NH(4)-N removal, whereas a high Fe decreased the efficiency significantly. The first 550 days operation of a pilot-scale reactor installed in the drinking water supply system showed a gradual increase in the efficiency, reaching to 95-100%, and stability in the performance even with increased flow rate from 210 to 860 L/day. The high efficiency of the present work was indicated because only less than 1 mg of NH(4)-N/L was left over in the treated water.

A hybrid plasma-chemical system for high-NOx flue gas treatment

NASA Astrophysics Data System (ADS)

Chmielewski, Andrzej G.; Zwolińska, Ewa; Licki, Janusz; Sun, Yongxia; Zimek, Zbigniew; Bułka, Sylwester

2018-03-01

The reduction of high concentrations of NOx and SO2 from simulated flue gas has been studied. Our aim was to optimise energy consumption for NOx and SO2 removal from off-gases from a diesel generator using heavy fuel oil. A hybrid process: electron beam (EB) plasma and wet scrubber has been applied. A much higher efficiency of NOx and SO2 removal was achieved in comparison to dry, ammonia free, electron beam flue gas treatment (EBFGT). A recorded removal from a concentration of 1500 ppm NOx reached 49% at a low dose of 6.5 kGy, while only 2% NOx was removed at the same dose if EB only was applied. For SO2, removal efficiency at a dose of 6.5 kGy increased from 15% (EB only) to 84% when sea water was used as a wet scrubber agent for 700 ppm SO2. The results of this study indicate that EB combined with wet scrubber is a very promising technology to be applied for removal of high concentrations of NOx and SO2 emitted from diesel engines operated e.g. on cargo ships, which are the main sources of SO2 and NOx pollution along their navigation routes.

Removal of natural organic matter and arsenic from water by electrocoagulation/flotation continuous flow reactor.

PubMed

Mohora, Emilijan; Rončević, Srdjan; Dalmacija, Božo; Agbaba, Jasmina; Watson, Malcolm; Karlović, Elvira; Dalmacija, Milena

2012-10-15

The performance of the laboratory scale electrocoagulation/flotation (ECF) reactor in removing high concentrations of natural organic matter (NOM) and arsenic from groundwater was analyzed in this study. An ECF reactor with bipolar plate aluminum electrodes was operated in the horizontal continuous flow mode. Electrochemical and flow variables were optimized to examine ECF reactor contaminants removal efficiency. The optimum conditions for the process were identified as groundwater initial pH 5, flow rate=4.3 l/h, inter electrode distance=2.8 cm, current density=5.78 mA/cm(2), A/V ratio=0.248 cm(-1). The NOM removal according to UV(254) absorbance and dissolved organic matter (DOC) reached highest values of 77% and 71% respectively, relative to the raw groundwater. Arsenic removal was 85% (6.2 μg As/l) relative to raw groundwater, satisfying the drinking water standards. The specific reactor electrical energy consumption was 17.5 kWh/kg Al. The specific aluminum electrode consumption was 66 g Al/m(3). According to the obtained results, ECF in horizontal continuous flow mode is an energy efficient process to remove NOM and arsenic from groundwater. Copyright © 2012 Elsevier B.V. All rights reserved.

Microalgal cultivation in wastewater from the fermentation effluent in Riboflavin (B2) manufacturing for biodiesel production.

PubMed

Sun, Xuefei; Wang, Cunwen; Li, Zihao; Wang, Weiguo; Tong, Yanjie; Wei, Jiang

2013-09-01

In this work, the acclimation of Chlorella pyrenoidosa in diluted wastewater was studied to produce biomass and remove chemical oxygen demand (COD), ammonia-N and phosphorous. The results indicated that the optimal conditions (the volume ratio of wastewater, light intensity, culture temperature, CO2 concentration in feeding gas) which could influence the wastewater treatment efficiency were 0.05, 250 photons m(-2) s(-1), 28 °C and 5%, respectively. Under these conditions, the removal efficiency of COD reached up to 89.2%, while the total nitrogen and total phosphorous decreased by 64.52% and 82.20%, respectively. With the second treatment, COD in the wastewater was further reduced to less than 100 mg/L while it was only reduced to 542.9 mg/L after the first treatment. The treated wastewater could be discharged directly or subjected to for further treatment for recycling. In addition, 1.25 g/L of the biomass and 38.27% (dry basis, w%) of lipid content were reached after microalgal cultivation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Arsenic oxidation by UV radiation combined with hydrogen peroxide.

PubMed

Sorlini, S; Gialdini, F; Stefan, M

2010-01-01

Arsenic is a widespread contaminant in the environment around the world. The most abundant species of arsenic in groundwater are arsenite [As(III)] and arsenate [As(V)]. Several arsenic removal processes can reach good removal yields only if arsenic is present as As(V). For this reason it is often necessary to proceed with a preliminary oxidation of As(III) to As(V) prior to the removal technology. Several studies have focused on arsenic oxidation with conventional reagents and advanced oxidation processes. In the present study the arsenic oxidation was evaluated using hydrogen peroxide, UV radiation and their combination in distilled and in real groundwater samples. Hydrogen peroxide and UV radiation alone are not effective at the arsenic oxidation. Good arsenic oxidation yields can be reached in presence of hydrogen peroxide combined with a high UV radiation dose (2,000 mJ/cm(2)). The quantum efficiencies for As(III) oxidation were calculated for both the UV photolysis and the UV/H(2)O(2) processes.

Simultaneous nitrogen, phosphorous, and hardness removal from reverse osmosis concentrate by microalgae cultivation.

PubMed

Wang, Xiao-Xiong; Wu, Yin-Hu; Zhang, Tian-Yuan; Xu, Xue-Qiao; Dao, Guo-Hua; Hu, Hong-Ying

2016-05-01

While reverse osmosis (RO) is a promising technology for wastewater reclamation, RO concentrate (ROC) treatment and disposal are important issues to consider. Conventional chemical and physical treatment methods for ROC present certain limitations, such as relatively low nitrogen and phosphorus removal efficiencies as well as the requirement of an extra process for hardness removal. This study proposes a novel biological approach for simultaneous removal of nitrogen, phosphorus, and calcium (Ca(2+)) and magnesium (Mg(2+)) ions from the ROC of municipal wastewater treatment plants by microalgal cultivation and algal biomass production. Two microalgae strains, Chlorella sp. ZTY4 and Scenedesmus sp. LX1, were used for batch cultivation of 14-16 days. Both strains grew well in ROC with average biomass production of 318.7 mg/L and lipid contents up to 30.6%, and nitrogen and phosphorus could be effectively removed with efficiencies of up to 89.8% and 92.7%, respectively. Approximately 55.9%-83.7% Ca(2+) could be removed from the system using the cultured strains. Mg(2+) removal began when Ca(2+) precipitation ceased, and the removal efficiency of the ion could reach up to 56.0%. The most decisive factor influencing Ca(2+) and Mg(2+) removal was chemical precipitation with increases in pH caused by algal growth. The results of this study provide a new biological approach for removing nitrogen, phosphorous, and hardness from ROC. The results suggest that microalgal cultivation presents new opportunities for applying an algal process to ROC treatment. The proposed approach serves dual purposes of nutrient and hardness reduction and production of lipid rich micro-algal biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Wastewater from the condensation and drying section of ABS was pretreated by microelectrolysis].

PubMed

Lai, Bo; Qin, Hong-Ke; Zhou, Yue-Xi; Song, Yu-Dong; Cheng, Jia-Yun; Sun, Li-Dong

2011-04-01

Wastewater from the condensation and drying section of acrylonitrile-butadiene-styrene (ABS) resin plant was pretreated by the microelectrolysis, and the effect of the influent pH value on the pollution removal efficiency of the microelectrolysis was mainly studied. In order to study the electrochemical action of the microelectrolysis for the degradation of toxic refractory organic pollutants, two control experiments of activated carbon and iron were set up. The results showed that the TOC removal efficiencies were all fluctuated between 40% and 60% under the condition of different influent pH values. The microelectrolysis can decompose and transform the toxic refractory organic pollutants and increase the BOD5/COD ratio from 0.32 to 0.60, which increased the biodegradability of ABS resin wastewater significantly. When the pH value of influent was 4.0, the BOD5/COD ratio of effluent reached 0.71. The result of UV-vis spectra indicates that the removal efficiency of the organic nitrile was the highest with influent pH was 4.0. Therefore, the best influent pH value of microelectrolysis was 4.0.

Full-scale production of VFAs from sewage sludge by anaerobic alkaline fermentation to improve biological nutrients removal in domestic wastewater.

PubMed

Liu, He; Han, Peng; Liu, Hongbo; Zhou, Guangjie; Fu, Bo; Zheng, Zhiyong

2018-07-01

A full-scale project of thermal-alkaline pretreatment and alkaline fermentation of sewage sludge was built to produce volatile fatty acids (VFAs) which was then used as external carbon source for improving biological nitrogen and phosphorus removals (BNPR) in wastewater plant. Results showed this project had efficient and stable performances in VFA production, sludge reduce and BNPR. Hydrolysis rate in pretreatment, VFAs yield in fermentation and total VS reduction reached 68.7%, 261.32 mg COD/g VSS and 54.19%, respectively. Moreover, fermentation liquid with VFA presented similar efficiency as acetic acid in enhancing BNPR, obtaining removal efficiencies of nitrogen and phosphorus up to 72.39% and 89.65%, respectively. Finally, the project also presented greater economic advantage than traditional processes, and the net profits for VFAs and biogas productions are 9.12 and 3.71 USD/m 3 sludge, respectively. Long-term operation indicated that anaerobic alkaline fermentation for VFAs production is technically and economically feasible for sludge carbon recovery. Copyright © 2018 Elsevier Ltd. All rights reserved.

Heard it through the grapevine: indirect networks and employee creativity.

PubMed

Hirst, Giles; Van Knippenberg, Daan; Zhou, Jing; Quintane, Eric; Zhu, Cherrie

2015-03-01

Social networks can be important sources of information and insights that may spark employee creativity. The cross-fertilization of ideas depends not just on access to information and insights through one's direct network-the people one actually interacts with--but at least as much on access to the indirect network one's direct ties connect one to (i.e., people one does not interact with directly, but with whom one's direct ties interact). We propose that the reach efficiency of this indirect network--its nonredundancy in terms of interconnections--is positively related to individual creativity. To help specify the boundaries of this positive influence of the indirect network, we also explore how many steps removed the indirect network still adds to creativity. In addition, we propose that the efficiency (nonredundancy) of one's direct network is important here, because more efficient direct networks give one access to indirect networks with greater reach efficiency. Our hypotheses were supported in a multilevel analysis of multisource survey data from 223 sales representatives nested within 11 divisions of a Chinese pharmaceutical company. This analysis also showed that the creative benefits of reach efficiency were evident for 3 and 4 degrees of separation but were greatest for indirect ties that depend only on one's direct ties. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Effect of water on sulfur dioxide (SO2) and nitrogen oxides (NOx) removal from flue gas in a direct current corona discharge reactor

NASA Astrophysics Data System (ADS)

Yang, Jiaxiang; Chi, Xiaochun; Dong, Limin

2007-05-01

A direct current (dc) corona discharge reactor composed of needle-plate electrodes in a glass container filled with flue gas was designed. To clarify the influence of water on discharge characteristics, water was introduced in the plasma reactor as electrode where plate electrode is immersed, under the application of dc voltage. Experiment results show that (1) corona wind forming between high-voltage needle electrode and water by corona discharge enhances the cleaning efficiency of flue gas due to the existence of water and the cleaning efficiency will increase with the increase of applied dc voltage within definite range and (2) both removal efficiencies of NOx and SO2 increased in the presence of water, which reach up to 98% for SO2, and about 85% for NOx under suitable conditions. These results play an important role in flue gas cleanup research.

Comparison of adsorption behavior of PCDD/Fs on carbon nanotubes and activated carbons in a bench-scale dioxin generating system.

PubMed

Zhou, Xujian; Li, Xiaodong; Xu, Shuaixi; Zhao, Xiyuan; Ni, Mingjiang; Cen, Kefa

2015-07-01

Porous carbon-based materials are commonly used to remove various organic and inorganic pollutants from gaseous and liquid effluents and products. In this study, the adsorption of dioxins on both activated carbons and multi-walled carbon nanotube was internally compared, via series of bench scale experiments. A laboratory-scale dioxin generator was applied to generate PCDD/Fs with constant concentration (8.3 ng I-TEQ/Nm(3)). The results confirm that high-chlorinated congeners are more easily adsorbed on both activated carbons and carbon nanotubes than low-chlorinated congeners. Carbon nanotubes also achieved higher adsorption efficiency than activated carbons even though they have smaller BET-surface. Carbon nanotubes reached the total removal efficiency over 86.8 % to be compared with removal efficiencies of only 70.0 and 54.2 % for the two other activated carbons tested. In addition, because of different adsorption mechanisms, the removal efficiencies of carbon nanotubes dropped more slowly with time than was the case for activated carbons. It could be attributed to the abundant mesopores distributed in the surface of carbon nanotubes. They enhanced the pore filled process of dioxin molecules during adsorption. In addition, strong interactions between the two benzene rings of dioxin molecules and the hexagonal arrays of carbon atoms in the surface make carbon nanotubes have bigger adsorption capacity.

Enhanced nitrate-nitrogen removal by modified attapulgite-supported nanoscale zero-valent iron treating simulated groundwater.

PubMed

Dong, Lei; Lin, Li; Li, Qingyun; Huang, Zhuo; Tang, Xianqiang; Wu, Min; Li, Chao; Cao, Xiaohuan; Scholz, Miklas

2018-05-01

Attapulgite (or palygorskite) is a magnesium aluminium phyllosilicate. Modified attapulgite-supported nanoscale zero-valent iron (NZVI) was created by a liquid-phase reduction method and then applied for nitrate-nitrogen (NO 3 -N) removal (transformation) in simulated groundwater. Nanoscale zero-valent iron was sufficiently dispersed on the surface of thermally modified attapulgite. The NO 3 -N removal efficiency reached up to approximately 83.8% with an initial pH values of 7.0. The corresponding thermally modified attapulgite-supported nanoscale zero-valent iron (TATP-NZVI) and NO 3 -N concentrations were 2.0 g/L and 20 mg/L respectively. Moreover, 72.1% of the water column NO 3 -N was converted to ammonium-nitrogen (NH 4 -N) within 6 h. The influence of environmental boundary conditions including dissolved oxygen (DO) concentration, light illumination and water temperature on NO 3 -N removal was also investigated with batch experiments. The results indicated that the DO concentration greatly impacted on NO 3 -N removal in the TATP-NZVI-contained solution, and the NO 3 -N removal efficiencies were 58.5% and 83.3% with the corresponding DO concentrations of 9.0 and 0.3 mg/L after 6 h of treatment, respectively. Compared to DO concentrations, no significant (p > 0.05) effect of light illumination on NO 3 -N removal and NH 4 -N generation was detected. The water temperature also has great importance concerning NO 3 -N reduction, and the removal efficiency of NO 3 -N at 25 °C was 1.25 times than that at 15 °C. For groundwater, therefore, environmental factors such as water temperature, anaerobic conditions and darkness could influence the NO 3 -N removal efficiency when TATP-NZVI is present. This study also demonstrated that TATP-NZVI has the potential to be developed as a suitable material for direct remediation of NO 3 -N-contaminated groundwater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spectroscopic characterization of DOM and the nitrogen removal mechanism during wastewater reclamation plant.

PubMed

Wang, Lei; Li, Ying-Jun; Xiong, Ying; Tan, Wen-Bing; Zhang, Lie-Yu; Li, Xiang; Wang, Xiao-Shu; Xu, Jian-Feng; Li, Tong-Tong; Wang, Jin-Sheng; Cai, Ming-Xuan; Xi, Bei-Dou; Wang, Di-Hua

2017-01-01

The performance of the Sha-he wastewater reclamation plant was evaluated in this study. To remove residual nitrogen after Anaerobic-Anoxic-Oxic (A2O) treatment, three multistage Anoxic-Oxic (A/O) were added to investigate the nitrogen removal efficiency and its mechanism. In addition, the constituents and evolution of dissolved organic matter (DOM) during wastewater reclamation was also investigated using a method combining fluorescence spectroscopy with fluorescence regional integration (FRI). The results suggested that multistage A/O treatment can effectively improve the nitrogen removal ability under low concentrations of carbon sources. The total nitrogen (TN) exhibits significantly positive correlation with fulvic acid-like materials and humic acid-like materials. The correlation coefficient for TN and fulvic acid-like substances (R2 = 0.810, P < 0.01) removal was greater than that of humic acid-like substances (R2 = 0.636, P < 0.05). The results indicate that nitrogen removal may be achieved with the fulvic-like and humic-like substances, and the removal effects were higher by fulvic acid-like substances than humic-like substances, mostly due to that the latter were relatively more difficult to be utilized as carbon source during the nitrogen removal process. The effluent water quality of biological treatment reached the first grade A standard of "Cities sewage treatment plant pollutant discharge standard" (GB18918-2002). In addition, the effluent from the membrane bioreactor reached the "Standards of reclaimed water quality" (SL368-2006).

Spectroscopic characterization of DOM and the nitrogen removal mechanism during wastewater reclamation plant

PubMed Central

Wang, Lei; Li, Ying-Jun; Xiong, Ying; Tan, Wen-Bing; Zhang, Lie-Yu; Li, Xiang; Wang, Xiao-Shu; Xu, Jian-feng; Li, Tong-Tong; Wang, Jin-Sheng; Cai, Ming-Xuan; Xi, Bei-Dou; Wang, Di-Hua

2017-01-01

The performance of the Sha-he wastewater reclamation plant was evaluated in this study. To remove residual nitrogen after Anaerobic-Anoxic-Oxic (A2O) treatment, three multistage Anoxic-Oxic (A/O) were added to investigate the nitrogen removal efficiency and its mechanism. In addition, the constituents and evolution of dissolved organic matter (DOM) during wastewater reclamation was also investigated using a method combining fluorescence spectroscopy with fluorescence regional integration (FRI). The results suggested that multistage A/O treatment can effectively improve the nitrogen removal ability under low concentrations of carbon sources. The total nitrogen (TN) exhibits significantly positive correlation with fulvic acid-like materials and humic acid-like materials. The correlation coefficient for TN and fulvic acid-like substances (R2 = 0.810, P < 0.01) removal was greater than that of humic acid-like substances (R2 = 0.636, P < 0.05). The results indicate that nitrogen removal may be achieved with the fulvic-like and humic-like substances, and the removal effects were higher by fulvic acid-like substances than humic-like substances, mostly due to that the latter were relatively more difficult to be utilized as carbon source during the nitrogen removal process. The effluent water quality of biological treatment reached the first grade A standard of “Cities sewage treatment plant pollutant discharge standard” (GB18918-2002). In addition, the effluent from the membrane bioreactor reached the “Standards of reclaimed water quality” (SL368-2006). PMID:29149172

Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands.

PubMed

Li, Peng; Zhun, Bao; Wang, Xuegang; Liao, PingPing; Wang, Guanghui; Wang, Lizhang; Guo, Yadan; Zhang, Weimin

2017-12-19

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH < 3.0, and the following iron-electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 μmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.

Integrating Fenton's process and ion exchange for olive mill wastewater treatment and iron recovery.

PubMed

Reis, Patrícia M; Martins, Pedro J M; Martins, Rui C; Gando-Ferreira, Licínio M; Quinta-Ferreira, Rosa M

2018-02-01

A novel integrated methodology involving Fenton's process followed by ion exchange (IE) was proposed for the treatment of olive mill wastewater. Fenton's process was optimized and it was able to remove up to 81% of chemical oxygen demand when pH 3.5, reaction time 1 h, [Fe 2+ ] = 50 mg L -1 and [Fe 2+ ]/[H 2 O 2 ] = 0.002 were applied. In spite of the potential of this treatment approach, final iron removal from the liquid typically entails pH increase and iron sludge production. The integration of an IE procedure using Lewatit TP 207 resin was found to be able to overcome this important environmental shortcoming. The resin showed higher affinity toward Fe 3+ than to Fe 2+ . However, the iron removal efficiency of an effluent coming from Fenton's was independent of the type of the initial iron used in the process. The presence of organic matter had no significant effect over the resin iron removal efficiency. Even if some efficiency decrease was observed when a high initial iron load was applied, the adsorbent mass quantity can be easily adapted to reach the desired iron removal. The use of IE is an interesting industrial approach able to surpass Fenton's peroxidation drawback and will surely boost its full-scale application in the treatment of bio-refractory effluents.

Electroadsorption of acilan blau dye from textile effluents by using activated carbon-perlite mixtures.

PubMed

Koparal, A S; Yavuz, Y; Bakir Ogütveren, U

2002-01-01

The feasibility of the removal of dye stuffs from textile effluents by electroadsorption has been investigated. An activated carbon-perlite mixture with a ratio of 8:1 for bipolarity has been used as the adsorbent. Conventional adsorption experiments have also been conducted for comparison. A bipolar trickle reactor has been used in the electroadsorption experiments. The model wastewater has been prepared by using acilan blau dye. Initial dye concentration, bed height between the electrodes, applied potential, flowrate, and the supporting electrolyte concentration have been examined as the parameters affecting the removal efficiency. A local textile plant effluent has been treated in the optimum values of these parameters obtained from the experimental studies. Adsorption kinetics and the amount of adsorbent required to reach the maximum removal efficiency have also been investigated and mass-transfer coefficients have been calculated for adsorption and electroadsorption. The results showed that a removal efficiency of up to 100% can be achieved with energy consumption values of 1.58 kWh/m3 of wastewater treated. However, energy consumption decreases to 0.09 kWh/m3 if an exit dye concentration of 4.65 mg/L is accepted. It can be concluded from this work that this method combines all of the advantages of the activated-carbon adsorption and electrolytic methods for the removal of dyes from wastewater.

An innovative wood-chip-framework substrate used as slow-release carbon source to treat high-strength nitrogen wastewater.

PubMed

Li, Huai; Chi, Zifang; Yan, Baixing; Cheng, Long; Li, Jianzheng

2017-01-01

Removal of nitrogen in wastewater before discharge into receiving water courses is an important consideration in treatment systems. However, nitrogen removal efficiency is usually limited due to the low carbon/nitrogen (C/N) ratio. A common solution is to add external carbon sources, but amount of liquid is difficult to determine. Therefore, a combined wood-chip-framework substrate (with wood, slag and gravel) as a slow-release carbon source was constructed in baffled subsurface-flow constructed wetlands to overcome the problem. Results show that the removal rate of ammonia nitrogen (NH 4 + -N), total nitrogen (TN) and chemical oxygen demand (COD) could reach 37.5%-85%, 57.4%-86%, 32.4%-78%, respectively, indicating the combined substrate could diffuse sufficient oxygen for the nitrification process (slag and gravel zone) and provide carbon source for denitrification process (wood-chip zone). The nitrification and denitrification were determined according to the location of slag/gravel and wood-chip, respectively. Nitrogen removal was efficient at the steady phase before a shock loading using slag-wood-gravel combined substrate because of nitrification-denitrification process, while nitrogen removal was efficient under a shock loading with wood-slag-gravel combined substrate because of ANAMMOX process. This study provides a new idea for wetland treatment of high-strength nitrogen wastewater. Copyright © 2016. Published by Elsevier B.V.

Evaluation and mechanism of ammonia nitrogen removal using sediments from a malodorous river

NASA Astrophysics Data System (ADS)

Chen, Xing; Jiang, Xia; Huang, Wei

2018-03-01

Malodorous rivers are among the major environmental problems of cities in developing countries. In addition to the unpleasant smell, the sediments of such rivers can act as a sink for pollutants. The excessive amount of ammonia nitrogen (NH3-N) in rivers is the main factor that causes the malodour. Therefore, a suitable method is necessary for sediment disposition and NH3-N removal in malodorous rivers. The sediment in a malodorous river (PS) in Beijing, China was selected and modified via calcination (PS-D), Na+ doping (PS-Na) and calcination-Na+ doping (PS-DNa). The NH3-N removal efficiency using the four sediment materials was evaluated, and results indicated that the NH3-N removal efficiency using the modified sediment materials could reach over 60%. PS-DNa achieved the highest NH3-N removal efficiency (90.04%). The kinetics study showed that the pseudo-second-order model could effectively describe the sorption kinetics and that the exterior activated site had the main function of P sorption. The results of the sorption isotherms indicated that the maximum sorption capacities of PS-Na, PS-D and PS-DNa were 0.343, 0.831 and 1.113 mg g-1, respectively, and a high temperature was favourable to sorption. The calculated thermodynamic parameters suggested that sorption was a feasible or spontaneous (ΔG < 0), entropy-driven (ΔS > 0), and endothermic (ΔH > 0) reaction.

[Removal of volatile organic compounds in soils by soil vapor extraction (SVE)].

PubMed

Yin, Fu-xiang; Zhang, Sheng-tian; Zhao, Xin; Feng, Ke; Lin, Yu-suo

2011-05-01

An experiment study has been carried out to investigate effects of the diameter of soil columns, the size of soil particulate and different contaminants on efficiency of simulated soil vapor extraction (SVE). Experiments with benzene, toluene, ethylbenzene and n-propylbenzene contaminated soils showed that larger bottom area/soil height (S/H) of the columns led to higher efficiency on removal of contaminants. Experiments with contaminated soils of different particulate size showed that the efficiency of SVE decreased with increases in soil particulate size, from 10 mesh to between 20 mesh and 40 mesh and removal of contaminants in soils became more difficult. Experiments with contaminated soils under different ventilation rates suggested that soil vapor extraction at a ventilation rate of 0.10 L x min(-1) can roughly remove most contaminants from the soils. Decreasing of contaminants in soils entered tailing stages after 12 h, 18 h and 48 h for benzene, toluene and ethylbenzene, respectively. Removal rate of TVOCs (Total VOCs) reached a level as high as 99.52%. The results of the experiment have indicated that molecule structure and properties of the VOCs are also important factors which have effects on removal rates of the contaminants. Increases in carbon number on the benzene ring, decreases in vapor pressure and volatile capability resulted in higher difficulties in soil decontamination. n-propylbenzene has a lower vapor pressure than toluene and ethylbenzene which led to a significant retard effect on desorption and volatilization of benzene and ethylbenzene.

A demonstration of biofiltration for VOC removal in petrochemical industries.

PubMed

Zhao, Lan; Huang, Shaobin; Wei, Zongmin

2014-05-01

A biotrickling filter demo has been set up in a petrochemical factory in Sinopec Group for about 10 months with a maximum inlet gas flow rate of 3000 m3 h(-1). The purpose of this project is to assess the ability of the biotrickling filter to remove hardly biodegradable VOCs such as benzene, toluene and xylene which are recalcitrant and poorly water soluble and commonly found in petrochemical factories. Light-weight hollow ceramic balls (Φ 5-8 cm) were used as the packing media treated with large amounts of circulating water (2.4 m3 m(-2) h(-1)) added with bacterial species. The controlled empty bed retention time (EBRT) of 240 s is a key parameter for reaching a removal efficiency of 95% for benzene, toluene, xylene, and 90% for total hydrocarbons. The demo has been successfully adopted and practically applied in waste air treatments in many petrochemical industries for about two years. The net inlet concentrations of benzene, toluene and xylene were varied from 0.5 to 3 g m(-3). The biofiltration process is highly efficient for the removal of hydrophobic and recalcitrant VOCs with various concentrations from the petrochemical factories. The SEM analysis of the bacterial community in the BTF during VOC removal showed that Pseudomonas putida and Klebsiella sp. phylum were dominant and shutdown periods could play a role in forming the community structural differences and leading to the changes of removal efficiencies.

Isolation of a bacterial strain, Acinetobacter sp. from centrate wastewater and study of its cooperation with algae in nutrients removal.

PubMed

Liu, Hui; Lu, Qian; Wang, Qin; Liu, Wen; Wei, Qian; Ren, Hongyan; Ming, Caibing; Min, Min; Chen, Paul; Ruan, Roger

2017-07-01

Algae were able to grow healthy on bacteria-containing centrate wastewater in a pilot-scale bioreactor. The batch experiment indicated that the co-cultivation of algae and wastewater-borne bacteria improved the removal efficiencies of chemical oxygen demand and total phosphorus in centrate wastewater to 93.01% and 98.78%, respectively. A strain of beneficial aerobic bacteria, Acinetobacter sp., was isolated and its biochemical characteristics were explored. Synergistic cooperation was observed in the growth of algae and Acinetobacter sp. Removal efficiencies of some nutrients were improved significantly by the co-cultivation of algae and Acinetobacter sp. After treatment, residual nutrients in centrate wastewater reached the permissible discharge limit. The cooperation between algae and Acinetobacter sp. was in part attributed to the exchange of carbon dioxide and oxygen between the algae and bacteria. This synergetic relationship between algae and Acinetobacter sp. provided a promising way to treat the wastewater by improving the nutrients removal and biomass production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

PubMed

Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

2016-04-06

Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

Bioremediation of Cd by strain GZ-22 isolated from mine soil based on biosorption and microbially induced carbonate precipitation.

PubMed

Zhao, Yue; Yao, Jun; Yuan, Zhimin; Wang, Tianqi; Zhang, Yiyue; Wang, Fei

2017-01-01

Microbially induced carbonate precipitation (MICP) is an emerging and promising bioremediation technology to restore the environment polluted by heavy metals. Carbonate-biomineralization microbe can immobilize heavy metals from mobile species into stable crystals. In the present manuscript, laboratory batch studies were conducted to evaluate the Cd removal ability based on biosorption and MICP, using carbonate-biomineralization microbe GZ-22 isolated from a mine soil. This strain was identified as a Bacillus sp. according to 16S rDNA gene sequence analysis. Results of batch experiments revealed that MICP of the strain GZ-22 showed a greater potential to remove Cd than biomass biosorption under different impact factors such as pH, initial Cd concentration, and contact time. The optimum pH for MICP was 6 (50.34 %), while for biomass biosorption, it was 5 (38.81 %). When the initial concentration of Cd was 10 mg/L, removal efficiency induced by MICP was 53.06 % after 3 h, which was about 11 % greater than the removal efficiency induced by adsorption. The Cd removal efficiency increased as reaction time. The maximum removal efficiency based on MICP can reach 60.72 % at 10 mg/L for 48 h compared with 56.27 % by biosorption. X-ray diffractomer (XRD) revealed that Cd was transformed into CdCO 3 by MICP of GZ-22. The present illustrated that the carbonate-biomineralization microbe GZ-22 can offer an effective and eco-friendly approach to immobilize soluble Cd and that MICP may play an important role in heavy metal bioremediation.

Efficient bioremediation of total organic carbon (TOC) in integrated aquaculture system by marine sponge Hymeniacidon perleve.

PubMed

Fu, Wantao; Wu, Yichun; Sun, Liming; Zhang, Wei

2007-08-15

The aim of this study is to investigate the potential of using marine sponge Hymeniacidon perleve to remove total organic carbon (TOC) in integrated aquaculture ecosystems. In sterilized natural seawater (SNSW) with different concentrations of TOC, H. perleve removed approximately 44-61% TOC during 24 h, with retention rates of ca. 0.19-1.06 mg/h .g-fresh sponge, however no particulate selectivity was observed. The highest initial TOC concentration, in which about 2.7 g fresh sponges could remove TOC effectively in 0.5-L SNSW, is 214.3-256.9 mg/L. The highest capacity of TOC removal and clearance rate (CR) by H. perleve is ca. 25.50 mg-TOC/g-fresh sponge and 7.64 mL/h . g-fresh sponge within 24 h, respectively. Until reaching the highest TOC removal capacity, the TOC removal capacity and clearance rate of H. perleve increased with initial TOC concentration, and dropped dramatically thereafter. After reaching the highest removal capacity, H. perleve could only remove relatively lower TOC concentration in seawater in subsequent run. The TOC removal kinetics in SNSW by H. perleve fitted very well with a S-shaped curve and a Logistic model equation (R(2) = 0.999). In different volumes of SNSW with a fixed initial TOC concentration, the weight/volume ratio of sponge biomass and SFNSW was optimized at 1.46 g-fresh sponge/1-L SNSW to achieve the maximum TOC removal. When co-cultured with marine fish Fugu rubripes for 15 days, H. perleve removed TOC excreted by F. rubripes with similar retention rates of ca. 0.15 mg/h . g-fresh sponge, and the sponge biomass increased by 22.8%. (c) 2007 Wiley Periodicals, Inc.

Evaluation of porous ceramic as microbial carrier of biofilter to remove toluene vapor.

PubMed

Lim, J S; Park, S J; Koo, J K; Park, H

2001-01-01

Three kinds of porous ceramic microbe media are fabricated from fly ash, diatomite and a mixture of fly ash and diatomite powders. Water holding capacity, density, porosity, pore size and distribution, compressive strength and micro-structure of each of the fabricated media are measured and compared. The fly ash and diatomite mixture ceramic is evaluated as the best biofilter medium among the three media because of its high compressive strength. It is selected as an experimental biofilter medium inoculated with thickened activated sludge. The laboratory scale biofilter was operated for 42 days under various experimental conditions varying in inlet toluene concentration and flow rate of contaminated air stream. The experimental result shows that the removal efficiency reaches up to 96.6% after 4 days from the start-up. Nutrient limitation is considered as a major factor limiting biofilter efficiency. Biofilter efficiency decreases substantially at the build-up of backpressure, which is largely due to the accumulation of excess VSS within the media. Periodic backwashing of the biofilter is necessary to remove excess biomass and attain stable long-term high removal efficiency. The bed needs to be backwashed when the overall pressure drop becomes greater than 460.6 Pa at space velocity of 100 h-1. A maximum flow rate of 444.85 g m-3hr-1 of toluene elimination by the mixture ceramic biofilter, which is higher than the previously reported values. This indicates that the fly ash and diatomite mixture ceramic biofilter can be effectively applied for removing toluene vapor.

Arsenic in drinking water wells on the Bolivian high plain: Field monitoring and effect of salinity on removal efficiency of iron-oxides-containing filters.

PubMed

Van Den Bergh, K; Du Laing, G; Montoya, Juan Carlos; De Deckere, E; Tack, F M G

2010-11-01

In the rural areas around Oruro (Bolivia), untreated groundwater is used directly as drinking water. This research aimed to evaluate the general drinking water quality, with focus on arsenic (As) concentrations, based on analysis of 67 samples from about 16 communities of the Oruro district. Subsequently a filter using Iron Oxide Coated Sand (IOCS) and a filter using a Composite Iron Matrix (CIM) were tested for their arsenic removal capacity using synthetic water mimicking real groundwater. Heavy metal concentrations in the sampled drinking water barely exceeded WHO guidelines. Arsenic concentrations reached values up to 964 μ g L⁻¹ and exceeded the current WHO provisional guideline value of 10 μ g L⁻¹ in more than 50% of the sampled wells. The WHO guideline of 250 mg L⁻¹ for chloride and sulphate was also exceeded in more than a third of the samples, indicating high salinity in the drinking waters. Synthetic drinking water could be treated effectively by the IOCS- and CIM-based filters reducing As to concentrations lower than 10 μ g L⁻¹. High levels of chloride and sulphate did not influence As removal efficiency. However, phosphate concentrations in the range from 4 to 24 mg L⁻¹ drastically decreased removal efficiency of the IOCS-based filter but had no effects on removal efficiency of the CIM-based filter. Results of this study can be used as a base for further testing and practical implementation of drinking water purification in the Oruro region.

Removal of viable bioaerosol particles with a low-efficiency HVAC filter enhanced by continuous emission of unipolar air ions.

PubMed

Huang, R; Agranovski, I; Pyankov, O; Grinshpun, S

2008-04-01

Continuous emission of unipolar ions has been shown to improve the performance of respirators and stationary filters challenged with non-biological particles. In this study, we investigated the ion-induced enhancement effect while challenging a low-efficiency heating, ventilation and air-conditioning (HVAC) filter with viable bacterial cells, bacterial and fungal spores, and viruses. The aerosol concentration was measured in real time. Samples were also collected with a bioaerosol sampler for viable microbial analysis. The removal efficiency of the filter was determined, respectively, with and without an ion emitter. The ionization was found to significantly enhance the filter efficiency in removing viable biological particles from the airflow. For example, when challenged with viable bacteria, the filter efficiency increased as much as four- to fivefold. For viable fungal spores, the ion-induced enhancement improved the efficiency by a factor of approximately 2. When testing with virus-carrying liquid droplets, the original removal efficiency provided by the filter was rather low: 9.09 +/- 4.84%. While the ion emission increased collection about fourfold, the efficiency did not reach 75-100% observed with bacteria and fungi. These findings, together with our previously published results for non-biological particles, demonstrate the feasibility of a new approach for reducing aerosol particles in HVAC systems used for indoor air quality control. Recirculated air in HVAC systems used for indoor air quality control in buildings often contains considerable number of viable bioaerosol particles because of limited efficiency of the filters installed in these systems. In the present study, we investigated - using aerosolized bacterial cells, bacterial and fungal spores, and virus-carrying particles - a novel idea of enhancing the performance of a low-efficiency HVAC filter utilizing continuous emission of unipolar ions in the filter vicinity. The findings described in this paper, together with our previously published results for non-biological particles, demonstrate the feasibility of the newly developed approach.

Optimization of moving bed biofilm reactors for oil sands process-affected water treatment: The effect of HRT and ammonia concentrations.

PubMed

Shi, Yijing; Huang, Chunkai; Gamal El-Din, Mohamed; Liu, Yang

2017-11-15

Two moving bed biofilm reactors (MBBRs) were optimized to improve the biodegradation of organic compounds in raw and ozonated OSPW by changing the hydraulic retention time (HRT) and the influent ammonia concentrations. During the five stages, the average COD removal reached 50.8±3.4%, 52.8±6.5%, 54.7±4.3%, 56.3±2.2%, and 58.0±2.3% respectively in raw OSPW MBBR, and 54.6±3.8%, 57.2±7.1%, 55.5±5.8%, 58.3±2.2%, and 60.7±2.3% respectively in ozonated OSPW MBBR. Welch's weighted ANOVA tests show that the increase in ammonia levels significantly improved the COD removal in the two systems, while the HRT was an important parameter for COD decrease in the raw OSPW MBBR. Compared to the HRT, the increase in ammonia concentrations were more beneficial for acid extractable fraction (AEF) degradation and the average AEF removal reached 29.80% (raw OSPW MBBR) and 16.50% (ozonated OSPW MBBR) by the end of the optimization (Stage V; HRT=96h, 60mg/L NH 4 + -N). >98% of the NH 4 + -N was removed in the two MBBR systems, showing good nitrification. Microtoxicity tests showed that no significant correlations were found between HRT/ammonia levels and the OSPW toxicity changes toward V. fischeri. Spearman's rank correlation analysis was applied for q-PCR data, showing that positive correlations between the removal efficiencies of AEF and NSR and NirK gene copies were observed in the raw OSPW MBBR system, while positive correlations between AEF removal efficiency and total bacteria gene, NSR, Nitro, and NirK gene copies were observed in the ozonated OSPW MBBR system. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of 226Ra and 228Ra from TENORM sludge waste using surfactants solutions.

PubMed

Attallah, M F; Hamed, Mostafa M; El Afifi, E M; Aly, H F

2015-01-01

The feasibility of using surfactants as extracting agent for the removal of radium species from TENORM sludge produced from petroleum industry is evaluated. In this investigation cationic and nonionic surfactants were used as extracting agents for the removal of radium radionuclides from the sludge waste. Two surfactants namely cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX100) were investigated as the extracting agents. Different parameters affecting the removal of both (226)Ra and (228)Ra by the two surfactants as well as their admixture were studied by the batch technique. These parameters include effect of shaking time, surfactants concentration and temperature as well as the effect of surfactants admixture. It was found that, higher solution temperature improves the removal efficiency of radium species. Combined extraction of nonionic and cationic surfactants produces synergistic effect in removal both (226)Ra and (228)Ra, where the removals reached 84% and 80% for (226)Ra and (228)Ra, respectively, were obtained using surfactants admixture. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioconjugated graphene oxide hydrogel as an effective adsorbent for cationic dyes removal.

PubMed

Soleimani, Khadijeh; Tehrani, Abbas Dadkhah; Adeli, Mohsen

2018-01-01

In this study, graphene oxide - cellulose nanowhiskers nanocomposite hydrogel was easily synthesized through covalent functionalization of cellulose nanowhiskers with graphene oxide via a facile approach. The nitrene chemistry applied for covalent functionalization of graphene oxide sheets. The surface morphology and chemical structure of the nanocomposite hydrogel were characterized by FTIR, TGA, Raman, XRD, elemental analysis and SEM. The UV/Visible absorption spectrum revealed that the obtained porous nanocomposite hydrogel can efficiently remove cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) from wastewater with high absorption power. The adsorption process showed that 100% of MB and 90% of RhB have been removed and the equilibrium state has been reached in 15min for low concentration solutions in accordance with the pseudo-second-order model. Moreover, the sample exhibited stable performance after being used several times. High adsorption capacity and easy recovery are the efficient factors making these materials as good adsorbent for water pollutants and wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Adsorptive removal of sulfonamide antibiotics in livestock urine using the high-silica zeolite HSZ-385.

PubMed

Fukahori, S; Fujiwara, T; Funamizu, N; Matsukawa, K; Ito, R

2013-01-01

The adsorptive removal of seven sulfonamide antibiotics using the high-silica zeolite HSZ-385 from distilled water, synthetic urine and real porcine urine was investigated. The pH greatly affected the adsorption efficiency, and the amounts of all sulfonamide antibiotics adsorbed on HSZ-385 decreased at alkaline conditions compared with that at neutral conditions. During storage, the pH and ammonium-ion concentration increased with urea hydrolysis for porcine urine. We clarified that the adsorption efficiency of sulfonamides in synthetic urine was equivalent to that in distilled water, suggesting that adsorption behavior was not affected by coexistent ions. HSZ-385 could adsorb sulfonamide antibiotics in real porcine urine even though the non-purgeable organic carbon concentration of porcine urine was 4-7 g/L and was two orders of magnitude higher than those of sulfonamides (10 mg/L each). Moreover, the adsorption of sulfonamides reached equilibrium within 15 min, suggesting that HSZ-385 is a promising adsorbent for removing sulfonamides from porcine urine.

Removal of High -Concentration and Refractory Organic Matter from Diosgenin Manufacture Wastewater : a case study of a demonstration project in Hubei Province, P R China

NASA Astrophysics Data System (ADS)

Bao, J.; Wang, L.

2009-12-01

Wastewater from diosgenin manufacture is dark brown (3,500 ~4,000 times of the chroma) and acidic(pH=0.8~1.5)with high concentration of organic matter(COD=25,000~38,000 mg/L)and poor biodegradability(BOD5/COD= 0.25~0.30). It is highly toxic to biota due to the water-soluble saponin, tannins and pectin. Therefore removal of the organic matter is of great importance before the discharge of the wastewater into the environment. Here we presented a set of data from a demonstration project in Hubei province, P R China with an improved technics. This technics, focusing on the treatment of diosgenin wastewater, included hydrolytic acidification, internal electrolysis, neutralization, aerating-improved Up-flow Anaerobic Sludge Bed (UASB) and bio-contact oxidation treatment in sequence to remove the organic matter. After 60 days of starting-up, the water quality from hydrolytic acidification reactor was greatly improved. The effluent became clear, indicating the obvious removal of suspended solids in the water; the ratio of BOD/COD increased to 0.44, suggesting an significant increase of biodegradability; the content of volatile fatty acid (VFA) increased from 22.6 mmol/L to 86.8 mmol/L and the volume loading of COD reached 9.48 kg COD/(m3d). Basically at this stage the removal efficiency of COD was stabilized at 25%. Further treatment was conducted on the effluent from hydrolytic acidification reactor through the Improved UASB Reactor after the internal electrolysis and neutralization. The Improved UASB Reactor can start up at room temperature with an influent of 1,500 mg/L COD and inflow rate of 50(m3/d). Then, temperature was increased gradually to 38 oC (± 2 oC) to optimize the growth of the mesophilic anaerobes in the reactor. The content of VFA of the effluent was controlled below 8 mmol/L to guarantee the pH in the range of 6.8~7.2. After 150 days of debugging, the COD of the influent to UASB increased to 9,600 mg/L, hydraulic retaining time (HRT) was around 70 hrs , the volume loading and the removal efficiency of COD reached 3.42 kg COD/(m3.d) and 75% respectively. Bio-contact oxidation process dealt with the effluent from the Improved UASB at room temperature. The HRT was 54 hrs and dissolved oxygen was controlled between 2 to 4 mg/L. Currently, the COD volume loading reached 1.05 kg COD/(m3.d) and the removal efficiency of COD was over 90%. The total removal efficiencies of COD and color were over 99% and 98% respectively in the overall process. The pH, color and COD content of the final effluent were 7, about 200 mg/L and 50 times of the chroma respectively. All these indexes met the criteria of “The National Discharge Standard of Industry Water Pollutants for Sapogenin”(GB 20425-2006). This work was supported by National Key Technologies R&D Program No. 2006BAB04A14-2), the Hubei Provincial Science and Technology Department (No. 2006AA305A05) and Wuhan Science and Technology Bureau (20066002101).

Investigation of applicability of Electro-Fenton method for the mineralization of naphthol blue black in water.

PubMed

Özcan, Ayça Atılır; Özcan, Ali

2018-07-01

In this study, mineralization and color removal performance of electro-Fenton method were examined in water containing naphthol blue black (NBB), a diazo dye. NBB was totally converted to intermediate species in a 15-min electrolysis at 60 mA, but complete de-colorization took 180 min. A very high oxidation rate constant ((3.35 ± 0.21) x 10 10  M -1 s -1 ) was obtained for NBB, showing its high reactivity towards hydroxyl radicals. A very high total organic carbon (TOC) removal value (45.23 mg L -1 ) was obtained in the first 60 min of the electro-Fenton treatment of an aqueous solution of NBB (0.25 mM) at 300 mA, indicating the mineralization efficiency of the electro-Fenton method. Mineralization current efficiency values obtained at 300 mA gradually decreased from 24.18% to 4.47% with the electrolysis time, indicating the presence of highly parasitic reactions. Gas chromatography-mass spectrometry analyses revealed that the cleavage of azo bonds of NBB led to formation of different aromatic and aliphatic oxidation intermediates. Ion chromatography analysis showed that ammonium, nitrate and sulfate were the mineralization end-products. The concentration of sulfate ion reached to its quantitative value at the 4th h of electrolysis. On the other hand, the total concentration of ammonium and nitrate ions reached to only 61% of the stoichiometric amount of initial nitrogen after a 7 h electrolysis. Finally, it can be said that the electro-Fenton method is a suitable and efficient method for the removal of NBB and its intermediates from water. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Influence of extracellular polymeric substance on enzyme hydrolysis of sludge under anaerobic condition].

PubMed

Chen, Wei; Jia, Yuan-Yuan; Zheng, Wei; Li, Xiao-Ming; Zhou, Jun; Yang, Qi; Luo, Kun

2011-08-01

The effect of extracellular polymeric substance (EPS) on the enzymatic solubilisation of sludge and the changes of chemical components was investigated. Sludge solubilization with and without EPS was studied in the enzymatic system, and in the normal system without enzyme addition, respectively. The result indicated that only EPS could be hydrolyzed when the enzyme addition less than 20 mg/g, while the cell lysis occurred significantly with the doses of enzymes increasing. Treatment with lysozyme for the original sludge was proved to have a higher hydrolysis efficiency, and the SCOD/TCOD rate reached up to 28.14%. And at the enzyme dosage of 60 mg/g, the VSS removal rate increased to 51.66% and the concentration of DNA attained 68.34 mg/g (calculated by VSS) after 48 h reaction, which were 29.01% and 59.63 mg/g higher than the control test, respectively, and were 24.86% and 53.39 mg/g higher than that with EPS removed in advance, respectively. Meanwhile, NH4+ -N, PO4(3-)-P and SCOD showed high dissolution efficiency, and the maximal concentrations achieved to 503 mg/L, 78.9 mg/L and 3171 mg/L, respectively. After removal of extracellular polymers, higher lysis efficiency was also observed by protease and cellulose, by which VSS reduction rate reached to 49.95% and 39.85%, respectively. The concentration of DNA showed a correlation coefficient of more than 0.9 with the concentrations of SCOD, NH4+ -N and PO4(3-)-P. And the highest hydrolysis rate obtained in 6 hours, which was about 3 hours earlier than the control test. Moreover, under those condition, sludge hydrolyzation could be well realized by only small amount of the enzyme addition.

Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water.

PubMed

Dai, Yunrong; Yao, Jun; Song, Yonghui; Liu, Xiaoling; Wang, Siyu; Yuan, Yu

2016-11-05

Multi-walled carbon nanotubes (MWCNTs) were used as modified materials to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The MWCNTs modified LCEFMs (MWCNTs-LCEFMs) were successfully fabricated via emulsion electrospinning, with active laccase and MWCNTs encapsulated inside the fibers. After modified by an optimal amount (1.5wt%, vs. polymer) of MWCNTs, the obtained MWCNTs-LCEFMs showed not only higher activity recovery (85.3%, vs. free laccase) than LCEFMs (71.2%), but also better storage and operational stability, which were mainly attributed to the promoted electron transfer in laccase-catalytic reaction. Furthermore, the specific surface area and tensile strength of MWCNTs-LCEFMs have also been enhanced nearly 2 and 3 times than those of LCEFMs, respectively. The MWCNTs-LCEFMs were applied to remove the widespread bisphenol A from water, where their removal efficiency reached above 90%, with the degradation efficiency accounting for over 80%, and their adsorption efficiency increased about 45% than that of LCEFMs. In addition, the endurances of MWCNTs-LCEFMs to environmental factors such as pH and temperature were also improved. Copyright © 2016 Elsevier B.V. All rights reserved.

Anaerobic digestion of grass: the effect of temperature applied during the storage of substrate on the methane production.

PubMed

Míchal, Pavel; Švehla, Pavel; Plachý, Vladimír; Tlustoš, Pavel

2017-07-01

Within this research, biogas production, representation of methane in biogas and volatile solids (VSs) removal efficiency were compared using batch tests performed with the samples of intensively and extensively planted grasses originating from public areas. Before the batch tests, the samples were stored at different temperatures achievable on biogas plants applying trigeneration strategy (-18°C, +3°C, +18°C and +35°C). Specific methane production from intensively planted grasses was relatively high (0.33-0.41 m 3 /kg VS) compared to extensively planted grasses (0.20-0.33 m 3 /kg VS). VSs removal efficiency reached 59.8-68.8% for intensively planted grasses and 34.6-56.5% for extensively planted grasses. Freezing the intensively planted grasses at -18°C proved to be an effective thermal pretreatment leading to high biogas production (0.61 m 3 /kg total solid (TS)), high representation of methane (64.0%) in biogas and good VSs removal efficiency (68.8%). The results of this research suggest that public areas or sport parks seem to be available, cheap and at the same time very effective feedstock for biogas production.

Microwave-Hydrothermal Treated Grape Peel as an Efficient Biosorbent for Methylene Blue Removal

PubMed Central

Ma, Lin; Jiang, Chunhai; Lin, Zhenyu; Zou, Zhimin

2018-01-01

Biosorption using agricultural wastes has been proven as a low cost and efficient way for wastewater treatment. Herein, grape peel treated by microwave- and conventional-hydrothermal processes was used as low cost biosorbent to remove methylene blue (MB) from aqueous solutions. The adsorption parameters including the initial pH value, dosage of biosorbents, contact time, and initial MB concentration were investigated to find the optimum adsorption conditions. The biosorbent obtained by microwave-hydrothermal treatment only for 3 min at 180 °C (microwave-hydrothermal treated grape peel, MGP) showed faster kinetics and higher adsorption capability than that produced by a conventional-hydrothermal process (hydrothermal treated grape peel, HGP) with a duration time of 16 h. The maximum adsorption capability of MGP under the optimum conditions (pH = 11, a dosage of 2.50 g/L) as determined with the Langmuir model reached 215.7 mg/g, which was among the best values achieved so far on biosorbents. These results demonstrated that the grape peel treated by a quick microwave-hydrothermal process can be a very promising low cost and efficient biosorbent for organic dye removal from aqueous solutions. PMID:29385041

Toxicity and removal efficiency of pharmaceutical metabolite clofibric acid by Typha spp.--potential use for phytoremediation?

PubMed

Dordio, Ana V; Duarte, Cátia; Barreiros, Margarida; Carvalho, A J Palace; Pinto, A P; da Costa, Cristina Teixeira

2009-02-01

A study was conducted to assess Typha spp.'s ability to withstand and remove, from water, a metabolite of blood lipid regulator drugs, clofibric acid (CA). At a concentration of 20 microg L(-1), Typha had removed >50% of CA within the first 48h, reaching a maximum of 80% by the end of the assay. Experimental conditions assured that photodegradation, adsorption to vessel walls and microbial degradation did not contribute to the removal. Exposure to higher CA concentrations did not affect Typha's photosynthetic pigments but the overall increase in enzyme activity (ascorbate and guaiacol peroxidases, catalase, superoxide dismutase) indicates that both roots and leaves were affected by the xenobiotic. Eventually, Typha seemed able to cope with the CA's induced oxidative damage suggesting its ability for phytoremediation of CA contaminated waters.

Denitrification of aging biogas slurry from livestock farm by photosynthetic bacteria.

PubMed

Yang, Anqi; Zhang, Guangming; Yang, Guang; Wang, Hangyao; Meng, Fan; Wang, Hongchen; Peng, Meng

2017-05-01

Huge amount of aging biogas slurry is in urgent need to be treated properly. However, due to high NH 3 -N concentration and low C/N ratio, this aging biogas slurry is refractory for traditional methods. Its denitrification has become a big challenge. In this paper, photosynthetic bacteria (PSB) were employed to handle this problem. The results showed denitrification of aging biogas slurry by PSB treatment was promising. The highest removal efficiency of NH 3 -N reached 99.75%, much higher than all other treatments. The removal of NH 3 -N followed pseudo zero order reaction under dark-aerobic condition. The better inoculation rate for NH 3 -N removal was 30%; and aerobic condition was more beneficial for NH 3 -N removal than anaerobic condition because of different metabolic pathways. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation and mechanism of ammonia nitrogen removal using sediments from a malodorous river

PubMed Central

Chen, Xing; Jiang, Xia

2018-01-01

Malodorous rivers are among the major environmental problems of cities in developing countries. In addition to the unpleasant smell, the sediments of such rivers can act as a sink for pollutants. The excessive amount of ammonia nitrogen (NH3−N) in rivers is the main factor that causes the malodour. Therefore, a suitable method is necessary for sediment disposition and NH3−N removal in malodorous rivers. The sediment in a malodorous river (PS) in Beijing, China was selected and modified via calcination (PS-D), Na+ doping (PS-Na) and calcination–Na+ doping (PS-DNa). The NH3−N removal efficiency using the four sediment materials was evaluated, and results indicated that the NH3−N removal efficiency using the modified sediment materials could reach over 60%. PS-DNa achieved the highest NH3−N removal efficiency (90.04%). The kinetics study showed that the pseudo-second-order model could effectively describe the sorption kinetics and that the exterior activated site had the main function of P sorption. The results of the sorption isotherms indicated that the maximum sorption capacities of PS-Na, PS-D and PS-DNa were 0.343, 0.831 and 1.113 mg g−1, respectively, and a high temperature was favourable to sorption. The calculated thermodynamic parameters suggested that sorption was a feasible or spontaneous (ΔG < 0), entropy-driven (ΔS > 0), and endothermic (ΔH > 0) reaction. PMID:29657816

In situ hydrothermal synthesis of a novel hierarchically porous TS-1/modified-diatomite composite for methylene blue (MB) removal by the synergistic effect of adsorption and photocatalysis.

PubMed

Yuan, Weiwei; Yuan, Peng; Liu, Dong; Yu, Wenbin; Laipan, Minwang; Deng, Liangliang; Chen, Fanrong

2016-01-15

Hierarchically porous TS-1/modified-diatomite composites with high removal efficiency for methylene blue (MB) were prepared via a facile in situ hydrothermal route. The surface charge state of the diatomite was modified to enhance the electrostatic interactions, followed by in situ hydrothermal coating with TS-1 nanoparticles. The zeolite loading amount in the composites could be adjusted by changing the hydrothermal time. The highest specific surface area and micropore volume of the obtained composites were 521.3m(2)/g and 0.254cm(3)/g, respectively, with an optimized zeolite loading amount of 96.8%. Based on the synergistic effect of efficient adsorption and photocatalysis resulting from the newly formed hierarchically porous structure and improved dispersion of TS-1 nanoparticles onto diatomite, the composites' removal efficiency for MB reached 99.1% after 2h of photocatalytic reaction, even higher than that observed using pure TS-1 nanoparticles. Moreover, the superior MB removal kinetics of the composites were well represented by a pseudo-first-order model, with a rate constant (5.28×10(-2)min(-1)) more than twice as high as that of pure TS-1 nanoparticles (2.43×10(-2)min(-1)). The significant dye removal performance of this novel TS-1/modified-diatomite composite indicates that it is a promising candidate for use in waste water treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

Treating low carbon/nitrogen (C/N) wastewater in simultaneous nitrification-endogenous denitrification and phosphorous removal (SNDPR) systems by strengthening anaerobic intracellular carbon storage.

PubMed

Wang, Xiaoxia; Wang, Shuying; Xue, Tonglai; Li, Baikun; Dai, Xian; Peng, Yongzhen

2015-06-15

A novel simultaneous nitrification denitrification and phosphorous removal-sequencing batch reactor (SNDPR-SBR) enriched with PAOs (phosphorus accumulating organisms), DPAOs (denitrifying PAOs), and GAOs (glycogen accumulating organisms) at the ratio of 2:1:1 was developed to achieve the simultaneous nutrient and carbon removal treating domestic wastewater with low carbon/nitrogen ratio (≤3.5). The SNDPR system was operated for 120 days at extended anaerobic stage (3 h) and short aerobic stage at low oxygen concentration (2.5 h) with short sludge retention time (SRT) of 10.9 d and hydraulic retention time (HRT) of 14.6 h. The results showed that at the stable operating stage, the average effluent chemical oxygen demand (COD) and PO4(3-)-P concentrations were 47.2 and 0.2 mg L(-1), respectively, the total nitrogen (TN) removal efficiency was 77.7%, and the SND efficiency reached 49.3%. Extended anaerobic stage strengthened the intracellular carbon (mainly poly-β-hydroxybutyrate, PHB) storage, efficiently utilized the organic substances in wastewater, and provided sufficient carbon sources for denitrification and phosphorus uptake without external carbon addition. Short aerobic stage at low oxygen concentration (dissolved oxygen (DO): 1 ± 0.3 mg L(-1)) achieved a concurrence of nitrification, endogenous denitrification, denitrifying and aerobic phosphorus uptake, and saved about 65% energy consumption for aeration. Microbial community analysis demonstrated that P removal was mainly performed by aerobic PAOs while N removal was mainly carried out by denitrifying GAOs (DGAOs), even though DPAOs were also participated in both N and P removal. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment of coal gasification wastewater by membrane bioreactor hybrid powdered activated carbon (MBR–PAC) system.

PubMed

Jia, Shengyong; Han, Hongjun; Hou, Baolin; Zhuang, Haifeng; Fang, Fang; Zhao, Qian

2014-12-01

A laboratory-scale membrane bioreactor hybrid powdered activated carbon (MBR–PAC) system was developed to treat coal gasification wastewater to enhance the COD, total phenols (TPh), NH4+ removals and migrate the membrane fouling. Since the MBR–PAC system operated with PAC dosage of 4 g L−1, the maximum removal efficiencies of COD, TPh and NH4+ reached 93%, 99% and 63%, respectively with the corresponding influent concentrations of 2.27 g L−1, 497 mg L−1 and 164 mg N L−1; the PAC extraction efficiencies of COD, TPh and NH4+ were 6%, 3% and 13%, respectively; the transmembrane pressure decreased 34% with PAC after 50 d operation. The results demonstrate that PAC played a key role in the enhancement of biodegradability and mitigation of membrane fouling.

Improved methane removal in exhaust gas from biogas upgrading process using immobilized methane-oxidizing bacteria.

PubMed

Sun, Meng-Ting; Yang, Zhi-Man; Fu, Shan-Fei; Fan, Xiao-Lei; Guo, Rong-Bo

2018-05-01

Methane in exhaust gas from biogas upgrading process, which is a greenhouse gas, could cause global warming. The biofilter with immobilized methane-oxidizing bacteria (MOB) is a promising approach for methane removal, and the selections of inoculated MOB culture and support material are vital for the biofilter. In this work, five MOB consortia were enriched at different methane concentrations. The MOB-20 consortium enriched at the methane concentration of 20.0% (v/v) was then immobilized on sponge and two particle sizes of volcanic rock in biofilters to remove methane in exhaust gas from biogas upgrading process. Results showed that the immobilized MOB performed more admirable methane removal capacity than suspended cells. The immobilized MOB on sponge reached the highest methane removal efficiency (RE) of 35%. The rough surface, preferable hydroscopicity, appropriate pore size and particle size of support material might favor the MOB immobilization and accordingly methane removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Combined anaerobic/aerobic digestion: effect of aerobic retention time on nitrogen and solids removal.

PubMed

Kim, Jongmin; Novak, John T

2011-09-01

A combined anaerobic/aerobic sludge digestion system was studied to determine the effect of aerobic solids retention time (SRT) on its solids and nitrogen removal efficiencies. After the anaerobic digester reached steady state, effluent from the anaerobic digester was fed to aerobic digesters that were operated at 2- to 5-day SRTs. The anaerobic system was fed with a mixture of primary and secondary sludge from a local municipal wastewater treatment plant. Both systems were fed once per a day. The aerobic reactor was continuously aerated with ambient air, maintaining dissolved oxygen level at 1.1 +/- 0.3 mg/L. At a 4-day or longer SRT, more than 11% additional volatile solids and 90% or greater ammonia were removed in the aerobic digester, while 32.8 mg-N/L or more nitrite/nitrate also was measured. Most total Kjeldahl nitrogen removal was via ammonia removal, while little organic nitrogen was removed in the aerobic digester.

Influence of power supply on the generation of ozone and degradation of phenol in a surface discharge reactor

NASA Astrophysics Data System (ADS)

Zhao, Yan; Shang, Kefeng; Duan, Lijuan; Li, Yue; An, Jiutao; Zhang, Chunyang; Lu, Na; Li, Jie; Wu, Yan

2013-03-01

A surface Dielectric Barrier Discharge (DBD) reactor was utilized to degrade phenol in water. Different power supplies applied to the DBD reactor affect the discharge modes, the formation of chemically active species and thus the removal efficiency of pollutants. It is thus important to select an optimized power supply for the DBD reactor. In this paper, the influence of the types of power supplies including alternate current (AC) and bipolar pulsed power supply on the ozone generation in a surface discharge reactor was measured. It was found that compared with bipolar pulsed power supply, higher energy efficiency of O3 generation was obtained when DBD reactor was supplied with 50Hz AC power supply. The highest O3 generation was approximate 4 mg kJ-1 moreover, COD removal efficiency of phenol wastewater reached 52.3% after 3 h treatment under an AC peak voltage of 2.6 kV.

Bacteria and virus removal effectiveness of ceramic pot filters with different silver applications in a long term experiment.

PubMed

van der Laan, H; van Halem, D; Smeets, P W M H; Soppe, A I A; Kroesbergen, J; Wubbels, G; Nederstigt, J; Gensburger, I; Heijman, S G J

2014-03-15

In 2012 more than 4 million people used a ceramic pot filter (CPF) as household water treatment system for their daily drinking water needs. In the normal production protocol most low cost filters are impregnated with a silver solution to enhance the microbial removal efficiency. The aim of this study was to determine the role of silver during the filtration and subsequent storage. Twenty-two CPFs with three different silver applications (non, only outside and both sides) were compared in a long-term loading experiment with Escherichia coli (K12 and WR1) and MS2 bacteriophages in natural challenge water under highly controlled laboratory circumstances. No significant difference in Log Removal Values were found between the filters with different silver applications. The results show that the storage time in the receptacle is the dominant parameter to reach E. coli inactivation by silver, and not the contact time during the filtration phase. The hypothesis that the absence of silver would enhance the virus removal, due to biofilm formation on the ceramic filter element, could not be confirmed. The removal effectiveness for viruses is still of major concern for the CPF. This study suggests that the ceramic pot filter characteristics, such as burnt material content, do not determine E. coli removal efficacies, but rather the contact time with silver during storage is the dominant parameter to reach E. coli inactivation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Energy efficiency for the removal of non-polar pollutants during ultraviolet irradiation, visible light photocatalysis and ozonation of a wastewater effluent.

PubMed

Santiago-Morales, Javier; Gómez, María José; Herrera-López, Sonia; Fernández-Alba, Amadeo R; García-Calvo, Eloy; Rosal, Roberto

2013-10-01

This study aims to assess the removal of a set of non-polar pollutants in biologically treated wastewater using ozonation, ultraviolet (UV 254 nm low pressure mercury lamp) and visible light (Xe-arc lamp) irradiation as well as visible light photocatalysis using Ce-doped TiO2. The compounds tracked include UV filters, synthetic musks, herbicides, insecticides, antiseptics and polyaromatic hydrocarbons. Raw wastewater and treated samples were analyzed using stir-bar sorptive extraction coupled with comprehensive two-dimensional gas chromatography (SBSE-CG × GC-TOF-MS). Ozone treatment could remove most pollutants with a global efficiency of over 95% for 209 μM ozone dosage. UV irradiation reduced the total concentration of the sixteen pollutants tested by an average of 63% with high removal of the sunscreen 2-ethylhexyl trans-4-methoxycinnamate (EHMC), the synthetic musk 7-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene (tonalide, AHTN) and several herbicides. Visible light Ce-TiO2 photocatalysis reached ~70% overall removal with particularly high efficiency for synthetic musks. In terms of power usage efficiency expressed as nmol kJ(-1), the results showed that ozonation was by far the most efficient process, ten-fold over Xe/Ce-TiO2 visible light photocatalysis, the latter being in turn considerably more efficient than UV irradiation. In all cases the efficiency decreased along the treatments due to the lower reaction rate at lower pollutant concentration. The use of photocatalysis greatly improved the efficiency of visible light irradiation. The collector area per order decreased from 9.14 ± 5.11 m(2) m(-3) order(-1) for visible light irradiation to 0.16 ± 0.03 m(2) m(-3) order(-1) for Ce-TiO2 photocatalysis. The toxicity of treated wastewater was assessed using the green alga Pseudokirchneriella subcapitata. Ozonation reduced the toxicity of treated wastewater, while UV irradiation and visible light photocatalysis limited by 20-25% the algal growth due to the accumulation of reaction by-products. Three transformation products were identified and tracked along the treatments. Copyright © 2013 Elsevier Ltd. All rights reserved.

Formation and removal of PCDD/Fs in a municipal waste incinerator during different operating periods.

PubMed

Wang, Hou Chuan; Hwang, Jyh Feng; Chi, Kai Hsien; Chang, Moo Been

2007-04-01

The PCDD/F concentrations and removal efficiencies achieved with air pollution control devices (APCDs) during different operating periods (start-up, normal operation, and shut-down) at an existing municipal waste incinerator (MWI) in Taiwan are evaluated via stack sampling and analysis. The MWI investigated is equipped with electrostatic precipitators (EP), wet scrubbers (WS), and selective catalytic reduction system (SCR) as APCDs. The sampling results indicate that the PCDD/F concentrations at the EP inlet during start-up period were 15 times higher than that measured during normal operation period. The PCDD/F concentration observed at shut-down period was close to that measured at normal operation period. The CO concentration was between 400 and 1000 ppm during start-up period, which was about 50 times higher compared with the normal operation. Hence, combustion condition significantly affected the PCDD/F formation concentration during the waste incineration process. In addition, the distributions of the PCDD/F congeners were similar at different operating periods. During the normal operation and shut-down periods, the EP decreases the PCDD/F concentration (based on TEQ) by 18.4-48.6%, while the removal efficiency of PCDD/Fs achieved with SCR system reaches 99.3-99.6%. Nevertheless, the PCDD/F removal efficiency achieved with SCR was only 42% during the 19-h start-up period due to the low SCR operating temperature (195 degrees C).

Treatment of ferrous-NTA-based NO x scrubber solution by an up-flow anaerobic packed bed bioreactor.

PubMed

Chandrashekhar, B; Sahu, Nidhi; Tabassum, Heena; Pai, Padmaraj; Morone, Amruta; Pandey, R A

2015-06-01

A bench scale system consisting of an up-flow packed bed bioreactor (UAPBR) made of polyurethane foam was used for the treatment and regeneration of aqueous solution of ferrous-NTA scrubbed with nitric oxide (NO). The biomass in the UAPBR was sequentially acclimatized under denitrifying and iron reducing conditions using ethanol as electron donor, after which nitric oxide (NO) gas was loaded continuously to the system by absorption. The system was investigated for different parameters viz. pH, removal efficiency of nitric oxide, biological reduction efficiency of Fe(II)NTA-NO and COD utilization. The Fe(II)NTA-NO reduction efficiency reached 87.8 % at a loading rate of 0.24 mmol L(-1) h(-1), while the scrubber efficiency reached more than 75 % with 250 ppm NO. Stover-Kincannon and a Plug-flow kinetic model based on Michaelis-Menten equation were used to describe the UAPBR performance with respect to Fe(II)NTA-NO and COD removal. The Stover-Kincannon model was found capable of describing the Fe(II)NTA-NO reduction (R m = 8.92 mM h(-1) and K NO = 11.46 mM h(-1)) while plug-flow model provided better fit to the COD utilization (U m = 66.62 mg L(-1) h(-1), K COD = 7.28 mg L(-1)). Analyses for pH, Fe(III)NTA, ammonium, nitrite concentration, and FTIR analysis of the medium samples indicated degradation of NTA, which leads to ammonium and nitrite accumulation in the medium, and affect the regeneration process.

An experimental model of COD abatement in MBBR based on biofilm growth dynamic and on substrates' removal kinetics.

PubMed

Siciliano, Alessio; De Rosa, Salvatore

2016-08-01

In this study, the performance of a lab-scale Moving Bed Biofilm Reactor (MBBR) under different operating conditions was analysed. Moreover, the dependence of the reaction rates both from the concentration and biodegradability of substrates and from the biofilm surface density, by means of several batch kinetic tests, was investigated. The reactor controls exhibited an increasing COD (Chemical Oxygen Demand) removal, reaching maximum yields (close to 90%) for influent loadings of up to12.5 gCOD/m(2)d. From this value, the pilot plant performance decreased to yields of only about 55% for influent loadings greater than 16 gCOD/m(2)d. In response to the influent loading increase, the biofilm surface density exhibited a logistic growing trend until reaching a maximum amount of total attached solids of about 9.5 g/m(2). The kinetic test results indicated that the COD removal rates for rapidly biodegradable, rapidly hydrolysable and slowly biodegradable substrates were not affected by the organic matter concentrations. Instead, first-order kinetics were detected with respect to biofilm surface density. The experimental results permitted the formulation of a mathematical model to predict the MBBR organic matter removal efficiency. The validity of the model was successfully tested in the lab-scale plant.

One-step synthesis of bifunctional PEGDA/TiO2 composite film by photopolymerization for the removal of Congo red

NASA Astrophysics Data System (ADS)

Wei, Yun-Yun; Sun, Xiao-Ting; Xu, Zhang-Run

2018-07-01

Wrinkled structures can provide enlarged surface areas for some living organisms to ingest nutrients. Imitating biological wrinkle structures offers an efficient way to enhance the adsorption surface for removing hazardous pollutants in wastewater. In this work, poly-(ethylene glycol) double acrylate (PEGDA)/TiO2 composite film with tunable surface wrinkles was synthesized. TiO2 nanoparticles were evenly immobilized in the PEGDA hydrogel simply by a facile photopolymerization method within 700 ms. Various wrinkle morphologies were obtained by precisely controlling UV exposure time. The composite film was characterized by X-ray diffraction, scanning electron microscopy, diffuse reflection spectroscopy, etc. Congo red was chosen as a model pollutant to demonstrate the adsorption and degradation capacity of the composite film. The experimental results showed that the introduction of wrinkled polymer improved the dispersibility of TiO2 nanoparticles. The removal efficiency reached 100% after 180-min adsorption in the darkness and 180-min UV irradiation. The composite film exhibited a much higher enrichment and photocatalysis capacity than the pure TiO2 powder, and could be developed as a reusable film for the removal of the organic pollutants in wastewater.

Hydrogen and lipid production from starch wastewater by co-culture of anaerobic sludge and oleaginous microalgae with simultaneous COD, nitrogen and phosphorus removal.

PubMed

Ren, Hong-Yu; Liu, Bing-Feng; Kong, Fanying; Zhao, Lei; Ren, Nanqi

2015-11-15

Anaerobic sludge (AS) and microalgae were co-cultured to enhance the energy conversion and nutrients removal from starch wastewater. Mixed ratio, starch concentration and initial pH played critical roles on the hydrogen and lipid production of the co-culture system. The maximum hydrogen production of 1508.3 mL L(-1) and total lipid concentration of 0.36 g L(-1) were obtained under the optimized mixed ratio (algae:AS) of 30:1, starch concentration of 6 g L(-1) and initial pH of 8. The main soluble metabolites in dark fermentation were acetate and butyrate, most of which can be consumed in co-cultivation. When sweet potato starch wastewater was used as the substrate, the highest COD, TN and TP removal and energy conversion efficiencies reached 80.5%, 88.7%, 80.1% and 34.2%, which were 176%, 178%, 200% and 119% higher than that of the control group (dark fermentation), respectively. This research provided a novel approach and achieved efficient simultaneous energy recovery and nutrients removal from starch wastewater by the co-culture system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Arsenic removal from water using a novel amorphous adsorbent developed from coal fly ash.

PubMed

Zhang, Kaihua; Zhang, Dongxue; Zhang, Kai

2016-01-01

A novel effective adsorbent of alumina/silica oxide hydrate (ASOH) for arsenic removal was developed through simple chemical reactions using coal fly ash. The iron-modified ASOH with enhancing adsorption activity was further developed from raw fly ash based on the in situ technique. The adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectrometry, scanning electron micrograph, laser particle size and Brunauer-Emmet-Teller surface area. The results show that the adsorbents are in amorphous and porous structure, the surface areas of which are 8-12 times that of the raw ash. The acidic hydrothermal treatment acts an important role in the formation of the amorphous structure of ASOH rather than zeolite crystal. A series of adsorption experiments for arsenic on them were studied. ASOH can achieve a high removal efficiency for arsenic of 96.4% from water, which is more than 2.5 times that of the raw ash. Iron-modified ASOH can enhance the removal efficiency to reach 99.8% due to the in situ loading of iron (Fe). The condition of synthesis pH = 2-4 is better for iron-modified ASOH to adsorb arsenic from water.

Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling

PubMed Central

Olatunji, Michael Adekunle; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Mahmud, Habibun Nabi Muhammad Ekramul

2016-01-01

A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor’s materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents. PMID:27706232

Simultaneous degradation of refractory organic pesticide and bioelectricity generation in a soil microbial fuel cell with different conditions.

PubMed

Cao, Xian; Yu, Chunyan; Wang, Hui; Zhou, Fang; Li, Xianning

2017-04-01

In this study, the soil microbial fuel cells (MFCs) were constructed based on sandy soil to remove the refractory organic pesticide hexachlorobenzene (HCB) in topsoil by a simple method. The construction of membraneless single-chamber soil MFCs by setting up the cathode- and the anode-activated carbon, inoculating the sludge and adding the co-substrates can promote HCB removal significantly. The results showed that HCB removal efficiencies in the soils contaminated with 40, 80  and 200 mg/kg were 71.14%, 62.15% and 50.06%, respectively, which were 18.65%, 18.46% and 19.17% higher than the control, respectively. The electricity generation of soil MFCs in different HCB concentrations was analyzed. The highest power density reached was 70.8 mW/m 2 , and an internal resistance of approximately 960 Ω was obtained when an external resistance loading of 1000 Ω was connected. Meanwhile, the influences of temperature, substrate species and substrate concentrations on soil MFCs initial electricity production were investigated. The addition of the anionic surfactant sodium dodecyl sulfate (SDS) into the soil MFCs system contributed to the improvement in HCB removal efficiency.

Coupled electrokinetics-adsorption technique for simultaneous removal of heavy metals and organics from saline-sodic soil.

PubMed

Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

2013-01-01

In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils.

Simultaneous removal of carbon and nitrogen by mycelial pellets of a heterotrophic nitrifying fungus-Penicillium sp. L1.

PubMed

Liu, Yuxiang; Hu, Tingting; Zhao, Jing; Lv, Yongkang; Ren, Ruipeng

2017-02-01

A novel heterotrophic nitrifying fungus, defined as Penicillium sp. L1, can form mycelial pellets in liquid medium in this study. The effects of inoculation method, C/N ratio, initial pH, and temperature were gradually evaluated to improve the simultaneous removal of total nitrogen (TN) and chemical oxygen demand (COD) in wastewater by Penicillium sp. L1. Results showed that compared with spore inoculation, 48 h pellet inoculum could significantly increase the pellet size (from about 1.5 mm to 3.2 mm) and improve the removal capability, particularly for COD removal (from less than 50-86.20%). The removal efficiencies of TN and COD reached 98.38% (from 136.01 mg/L to 2.20 mg/L) and 92.40% (from 10,720 mg/L to 815 mg/L) under the following conditions: C/N 36, pH 3, 30°C, and inoculation with 48 h pellets. The pellet diameter reached 4.8 mm after 4-day cultivation. In this case, Penicillium sp. L1 removed TN from 415.93 mg/L to 43.39 mg/L, as well as COD from 29,533 mg/L to 8850 mg/L. Overall, the results indicated that the pellet size was closely related to the pollutant-removal ability of Penicillium sp. L1. Furthermore, mycelial pellets (4.8 mm, dead) only adsorbed 38.08% TN (from 125.45 mg/L to 77.78 mg/L), which indicated that adsorption did not play a major role in the nitrogen-removal process. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Ethyl lactate-EDTA composite system enhances the remediation of the cadmium-contaminated soil by autochthonous willow (Salix x aureo-pendula CL 'J1011') in the lower reaches of the Yangtze River.

PubMed

Li, Jiahua; Sun, Yuanyuan; Yin, Ying; Ji, Rong; Wu, Jichun; Wang, Xiaorong; Guo, Hongyan

2010-09-15

In order to explore a practical approach to the remediation of the cadmium (Cd)-contaminated soil in the lower reaches of the Yangtze River, we evaluated the effects of a local willow (Salix x aureo-pendula CL 'J1011') of absorbing, accumulating, and translocating Cd; and assessed the potential of chelator ethylenediaminetetraacetic acid (EDTA) in combination with ethyl lactate for enhancing the efficiency of the willow in removing Cd in two water-culture growth chamber trials and a field one. The willow showed a high tolerance to Cd in growth chamber trial 1 where the Cd concentration in the medium reached up to 25 mg L(-1) medium, and the bioaccumulation factors (BAFs) of the shoots for Cd rose from 3.8 to 7.4 as the Cd concentration in the medium was elevated from 5 to 25 mg L(-1) medium. In growth chamber trial 2, the average Cd removal rates in two treatments with EDTA and ethyl lactate (molar ratios of EDTA to ethyl lactate=68/39 and 53.5/53.5, respectively) reached 0.71 mg d(-1) pot(-1) for the duration of Day 5-8 and 0.59 mg d(-1) pot(-1) for that of Day 8-11, which were 5- and 4-fold of their counterparts in the control, respectively. In the field trial, for the remediational duration of 45 days, three treatments-willow alone, willow combined with EDTA, and willow combined with EDTA and ethyl lactate-led to decreases in the Cd concentration in soil by 5%, 20%, and 29%, respectively; increases in that in the leaves by 14.6%, 56.7%, and 146.5%, respectively; and increases in that in the stems by 15.6%, 41.2%, and 87.4%, respectively, compared to their counterparts on Day 0. These results indicate that EDTA combined with ethyl lactate significantly enhanced the efficiency of willow in removing Cd from the soil. Therefore, a phytoextration system consisting of the autochthonous willow, EDTA, and ethyl lactate has high potential for the remediation of the Cd-polluted soil in the lower reaches of the Yangtze River. Copyright 2010 Elsevier B.V. All rights reserved.

Selective removal of cesium by ammonium molybdophosphate - polyacrylonitrile bead and membrane.

PubMed

Ding, Dahu; Zhang, Zhenya; Chen, Rongzhi; Cai, Tianming

2017-02-15

The selective removal of radionuclides with extremely low concentrations from environmental medium remains a big challenge. Ammonium molybdophosphate possess considerable selectivity towards cesium ion (Cs + ) due to the specific ion exchange between Cs + and NH 4 + . Ammonium molybdophosphate - polyacrylonitrile (AMP-PAN) membrane was successfully prepared for the first time in this study. Efficient removal of Cs + (95.7%, 94.1% and 91.3% of 1mgL -1 ) from solutions with high ionic strength (400mgL -1 of Na + , Ca 2+ or K + ) was achieved by AMP-PAN composite. Multilayer chemical adsorption process was testified through kinetic and isotherm studies. The estimated maximum adsorption capacities even reached 138.9±21.3mgg -1 . Specifically, the liquid film diffusion was identified as the rate-limiting step throughout the removal process. Finally, AMP-PAN membrane could eliminate Cs + from water effectively through the filtration adsorption process. Copyright © 2016 Elsevier B.V. All rights reserved.

Identifying the influential aquifer heterogeneity factor on nitrate reduction processes by numerical simulation

NASA Astrophysics Data System (ADS)

Jang, E.; He, W.; Savoy, H.; Dietrich, P.; Kolditz, O.; Rubin, Y.; Schüth, C.; Kalbacher, T.

2017-01-01

Nitrate reduction reactions in groundwater systems are strongly influenced by various aquifer heterogeneity factors that affect the transport of chemical species, spatial distribution of redox reactive substances and, as a result, the overall nitrate reduction efficiency. In this study, we investigated the influence of physical and chemical aquifer heterogeneity, with a focus on nitrate transport and redox transformation processes. A numerical modeling study for simulating coupled hydrological-geochemical aquifer heterogeneity was conducted in order to improve our understanding of the influence of the aquifer heterogeneity on the nitrate reduction reactions and to identify the most influential aquifer heterogeneity factors throughout the simulation. Results show that the most influential aquifer heterogeneity factors could change over time. With abundant presence of electron donors in the high permeable zones (initial stage), physical aquifer heterogeneity significantly influences the nitrate reduction since it enables the preferential transport of nitrate to these zones and enhances mixing of reactive partners. Chemical aquifer heterogeneity plays a comparatively minor role. Increasing the spatial variability of the hydraulic conductivity also increases the nitrate removal efficiency of the system. However, ignoring chemical aquifer heterogeneity can lead to an underestimation of nitrate removals in long-term behavior. With the increase of the spatial variability of the electron donor, i.e. chemical heterogeneity, the number of the ;hot spots; i.e. zones with comparably higher reactivity, should also increase. Hence, nitrate removal efficiencies will also be spatially variable but overall removal efficiency will be sustained if longer time scales are considered and nitrate fronts reach these high reactivity zones.

Health risk assessment of phthalate esters (PAEs) in drinking water sources of China.

PubMed

Wang, Wen-Long; Wu, Qian-Yuan; Wang, Chao; He, Tao; Hu, Hong-Ying

2015-03-01

Phthalate esters (PAEs) with endocrine disruption effects and carcinogenicity are widely detected in water environment. Occurrences of PAEs in source water and removal efficiencies of PAEs by drinking water treatment plants (DWTPs) in China were surveyed from publications in the last 10 years. Concentration of diethylhexyl phthalate (DEHP) in source water with median value of 1.3 μg/L was higher than that of dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP). If the removal efficiencies of DEHP and DnBP reached 60 and 90 %, respectively, the calculated PAE concentration in drinking water can generally meet Standards for Drinking Water Quality in China. The health risks of PAEs, including non-carcinogenic and carcinogenic risks via the "water source-DWTP-oral ingestion/dermal permeation" pathway, were evaluated with Monte Carlo simulation and sensitivity analysis under certain removal efficiencies from 0 to 95 %. The carcinogenic risk of DEHP was lower than the upper acceptable carcinogenic risk level (10(-4)), while the probability of DEHP's carcinogenic risk between lower (10(-6)) and upper (10(-4)) acceptable carcinogenic risk level decreased from about 21.2 to 0.4 % through increasing DEHP removal efficiency from 0 to 95 %. The non-carcinogenic risk of DEHP was higher than that of DEP and DnBP. In all cases, the total non-carcinogenic risk of DEP, DnBP, and DEHP was lower than 1, indicating that there would be unlikely incremental non-carcinogenic risk to humans. Both carcinogenic risk and non-carcinogenic risk of PAEs in drinking water to female were a little higher than those to male.

Performance of slow rate systems for treatment of domestic wastewater.

PubMed

Tzanakakis, V E; Paranychianakis, N V; Angelakis, A N

2007-01-01

The performance of slow rate (SR) systems in terms of treatment efficiency, environmental and health risks, and land sustainability was investigated over a three-year period in a rural community close to Iraklio, Greece. Four plant species (Acacia cyanophylla, Eucalyptus camandulensis, Populus nigra and Arundo donax) were used in order to investigate the role of vegetation in the treatment of wastewater and in biomass production. Wastewater effluent was pre-treated in a septic tank before its application to land. Applied hydraulic loading rates were based on crop water requirements which were determined separately for each plant species. The evaluation of treatment performance was accomplished by measuring COD, TKN, NH3-N, NO3-N, total and reactive P, TC and FC in soil solution samples taken at different depths (15, 30 and 60 cm). SR systems showed great potential for COD, TKN and NH4-N removal which reached 89, 90 and 94%, respectively at a depth of 15 cm. An outstanding removal was also observed for TC and FC which reached 99.99%. The concentration of both P and NO3-N in soil solution increased with the passage of time, but it was lower in winter. Despite the differences in the application rates among the SR systems planted with different plant species, the treatment efficiency was not affected. Moreover, increasing the soil depth from 15 to 60 cm had no effect on the treatment efficiency of the SR systems.

Zeolitic imidazolate framework-8 for efficient adsorption and removal of Cr(VI) ions from aqueous solution.

PubMed

Niknam Shahrak, Mahdi; Ghahramaninezhad, Mahboube; Eydifarash, Mohsen

2017-04-01

Heavy metals are emerging toxic pollutants in which the development of advanced materials for their efficient adsorption and separation is thus of great significance in environmental sciences point of view. In this study, one of the zinc-based zeolitic imidazolate framework materials, known as ZIF-8, has been synthesized and used for chromium(VI) contaminant removal from water for the first time. The as-synthesized ZIF-8 adsorbent was characterized with different methodologies such as powder X-ray diffraction (XRD), thermo-gravimetric analysis, FT-IR, nuclear magnetic resonance spectroscopy, and UV-Vis spectra of solid state. Various factors affecting removal percentage (efficiency) are experimentally investigated including pH of solution, adsorbent dosage, contact time and initial concentration of Cr(VI) to achieve the optimal condition. The obtained results indicate that the ZIF-8 shows good performance for the Cr(VI) removal from aqueous solution so that 60 min mixing of 2 g of ZIF-8 adsorbent with the 2.5 ppm of Cr(VI) solution in a neutral environment will result in the highest separation efficiency around 70%. The time needed to reach the equilibrium (maximum separation efficiency) is only 60 min for a concentration of 5 mg L -1 . Structure stability in the presence of water is also carefully examined by XRD determination of ZIF-8 under different contact times in aqueous solution, which suggests that the structure is going to be destructed after 60 min immersed in solution. Electrostatic interaction of Cr(VI) anions by positively charged ZIF-8 is responsible for Cr(VI) adsorption and separation. Moreover, equilibrium adsorption study reveals that the Cr(VI) removal process using ZIF-8 nicely fits the Langmuir and Toth isotherm models which mean the adsorbent has low heterogeneous surface with different distributions of adsorption energies during Cr(VI) adsorption. Equilibrium adsorption capacity is observed around 0.25 for 20 mg L -1 of initial Cr(VI) solutions.

Microbial fuel cells for direct electrical energy recovery from urban wastewaters.

PubMed

Capodaglio, A G; Molognoni, D; Dallago, E; Liberale, A; Cella, R; Longoni, P; Pantaleoni, L

2013-01-01

Application of microbial fuel cells (MFCs) to wastewater treatment for direct recovery of electric energy appears to provide a potentially attractive alternative to traditional treatment processes, in an optic of costs reduction, and tapping of sustainable energy sources that characterizes current trends in technology. This work focuses on a laboratory-scale, air-cathode, and single-chamber MFC, with internal volume of 6.9 L, operating in batch mode. The MFC was fed with different types of substrates. This study evaluates the MFC behaviour, in terms of organic matter removal efficiency, which reached 86% (on average) with a hydraulic retention time of 150 hours. The MFC produced an average power density of 13.2 mW/m(3), with a Coulombic efficiency ranging from 0.8 to 1.9%. The amount of data collected allowed an accurate analysis of the repeatability of MFC electrochemical behaviour, with regards to both COD removal kinetics and electric energy production.

Study on anaerobic treatment of wastewater containing hexavalent chromium.

PubMed

Xu, Yan-bin; Xiao, Hua-hua; Sun, Shui-yu

2005-06-01

A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and COD(Cr) of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr6+ removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms.

Degradation of cyanotoxins (microcystin) in drinking water using photoelectrooxidation.

PubMed

Garcia, A C A; Rodrigues, M A S; Xavier, J L N; Gazulla, V; Meneguzzi, A; Bernardes, A M

2015-05-01

The discharge of sewage and industrial effluents containing high concentrations of pollutants in water bodies increases eutrophication. Cyanobacteria, some of the organisms whose growth is promoted by high nutrient concentrations, are resistant and produce several types of toxins, known as cyanotoxins, highly harmful to human beings. Current water treatment systems for the public water supply are not efficient in degradation of toxins. Advanced oxidation processes (AOP) have been tested for the removal of cyanotoxins, and the results have been positive. This study examines the application of photoelectrooxidation in the degradation of cyanotoxins (microcystins). The performance of the oxidative processes involved was evaluated separately: Photocatalysis, Electrolysis and Photoelectrooxidation. Results showed that the electrical current and UV radiation were directly associated with toxin degradation. The PEO system is efficient in removing cyanotoxins, and the reduction rate reached 99%. The final concentration of toxin was less than 1 µg/L of microcystin in the treated solution.

Biofiltration of waste gases containing a mixture of formaldehyde and methanol.

PubMed

Prado, Oscar J; Veiga, María C; Kennes, Christian

2004-08-01

Several biofilters and biotrickling filters were used for the treatment of a mixture of formaldehyde and methanol; and their efficiencies were compared. Results obtained with three different inert filter bed materials (lava rock, perlite, activated carbon) suggested that the packing material had only little influence on the performance. The best results were obtained in a biotrickling filter packed with lava rock and fed a nutrient solution that was renewed weekly. A maximum formaldehyde elimination capacity of 180 g m(-3) h(-1) was reached, while the methanol elimination capacity rose occasionally to more than 600 g m(-3) h(-1). Formaldehyde degradation was affected by the inlet methanol concentration. Several combinations of load vs empty bed residence time (EBRTs of 71.9, 46.5, 30.0, 20.7 s) were studied, reaching a formaldehyde elimination capacity of 112 g m(-3) h(-1) with about 80% removal efficiency at the lowest EBRT (20.7 s).

A study on the use of the BioBall® as a biofilm carrier in a sequencing batch reactor.

PubMed

Masłoń, Adam; Tomaszek, Janusz A

2015-11-01

Described in this study are experiments conducted to evaluate the removal of organics and nutrients from synthetic wastewater by a moving bed sequencing batch biofilm reactor using BioBall® carriers as biofilm media. The work involving a 15L-laboratory scale MBSBBR (moving bed sequencing batch biofilm reactor) model showed that the wastewater treatment system was based on biochemical processes taking place with activated sludge and biofilm microorganisms developing on the surface of the BioBall® carriers. Classical nitrification and denitrification and the typical enhanced biological phosphorus removal process were achieved in the reactor analyzed, which operated with a volumetric organic loading of 0.84-0.978gCODL(-1)d(-1). The average removal efficiencies for COD, total nitrogen and total phosphorus were found to be 97.7±0.5%, 87.8±2.6% and 94.3±1.3%, respectively. Nitrification efficiency reached levels in the range 96.5-99.7%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anodic oxidation of slaughterhouse wastewater on boron-doped diamond: process variables effect.

PubMed

Abdelhay, Arwa; Jum'h, Inshad; Abdulhay, Enas; Al-Kazwini, Akeel; Alzubi, Mashael

2017-12-01

A non-sacrificial boron-doped diamond electrode was prepared in the laboratory and used as a novel anode for electrochemical oxidation of poultry slaughterhouse wastewater. This wastewater poses environmental threats as it is characterized by a high content of recalcitrant organics. The influence of several process variables, applied current density, initial pH, supporting electrolyte nature, and concentration of electrocoagulant, on chemical oxygen demand (COD) removal, color removal, and turbidity removal was investigated. Results showed that raising the applied current density to 3.83 mA/cm 2 has a positive effect on COD removal, color removal, and turbidity removal. These parameters increased to 100%, 90%, and 80% respectively. A low pH of 5 favored oxidants generation and consequently increased the COD removal percentage to reach 100%. Complete removal of COD had occurred in the presence of NaCl (1%) as supporting electrolyte. Na 2 SO 4 demonstrated lower efficiency than NaCl in terms of COD removal. The COD decay kinetics follows the pseudo-first-order reaction. The simultaneous use of Na 2 SO 4 and FeCl 3 decreased the turbidity in wastewater by 98% due to electrocoagulation.

Lindane removal by pure and mixed cultures of immobilized actinobacteria.

PubMed

Saez, Juliana M; Benimeli, Claudia S; Amoroso, María J

2012-11-01

Lindane (γ-HCH) is an organochlorine insecticide that has been widely used in developing countries. It is known to persist in the environment and can cause serious health problems. One of the strategies adopted to remove lindane from the environment is bioremediation using microorganisms. Immobilized cells present advantages over free suspended cells, like their high degradation efficiency and protection against toxins. The aims of this work were: (1) To evaluate the ability of Streptomyces strains immobilized in four different matrices to remove lindane, (2) To select the support with optimum lindane removal by pure cultures, (3) To assay the selected support with consortia and (4) To evaluate the reusability of the immobilized cells. Four Streptomyces sp. strains had previously shown their ability to grow in the presence of lindane. Lindane removal by microorganisms immobilized was significantly higher than in free cells. Specifically immobilized cells in cloth sachets showed an improvement of around 25% in lindane removal compared to the abiotic control. Three strains showed significantly higher microbial growth when they were entrapped in silicone tubes. Strains immobilized in PVA-alginate demonstrated lowest growth. Mixed cultures immobilized inside cloth sachets showed no significant enhancement compared to pure cultures, reaching a maximum removal of 81% after 96 h for consortium I, consisting of the four immobilized strains together. Nevertheless, the cells could be reused for two additional cycles of 96 h each, obtaining a maximum removal efficiency of 71.5% when each of the four strains was immobilized in a separate bag (consortium III). Copyright © 2012 Elsevier Ltd. All rights reserved.

Active slag filters-simple and sustainable phosphorus removal from wastewater using steel industry byproduct.

PubMed

Pratt, C; Shilton, A

2010-01-01

Active filtration, where effluent is passed through a reactive substrate such as steel slag, offers a simple and cost-effective option for removing phosphorus (P) from effluent. This work summarises a series of studies that focused on the world's only full-scale active slag filter operated through to exhaustion. The filter achieved 75% P-removal during its first 5 years, reaching a retention capacity of 1.23 g P/kg slag but then its performance sharply declined. Scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and chemical extractions revealed that P sequestration was primarily achieved via adsorption onto iron (Fe) oxyhydroxides on the slag's surface. It was concluded that batch equilibrium tests, whose use has been repeatedly proposed in the literature, cannot be used as an accurate predictor of filter adsorption capacity because Fe oxyhydroxides form via chemical weathering in the field, and laboratory tests don't account for this. Research into how chemical conditions affect slag's P retention capacity demonstrated that near-neutral pH and high redox are optimal for Fe oxyhydroxide stability and overall filter performance. However, as Fe oxyhydroxide sites fill up, removal capacity becomes exhausted. Attempts to regenerate P removal efficiency using physical techniques proved ineffective contrary to dogma in the literature. Based on the newly-developed understanding of the mechanisms of P removal, chemical regeneration techniques were investigated and were shown to strip large quantities of P from filter adsorption sites leading to a regenerated P removal efficiency. This raises the prospect of developing a breakthrough technology that can repeatedly remove and recover P from effluent.

Effect of Bisphenol A on the extremophilic microalgal strain Picocystis sp. (Chlorophyta) and its high BPA removal ability.

PubMed

Ben Ouada, Sabrine; Ben Ali, Rihab; Leboulanger, Christophe; Ben Ouada, Hatem; Sayadi, Sami

2018-08-30

Bisphenol A (BPA) effects and removal by an alkaliphilic chlorophyta, Picocystis, were assessed. BPA at low concentrations (0-25 mg L -1 ) did not inhibit the Picocystis growth and photosynthesis during 5 days of exposure. At higher BPA concentrations (50 and 75 mg L -1 ), the growth inhibition did not exceed 43%. The net photosynthetic activity was dramatically reduced at high BPA concentrations while, the PSII activity was less affected. The exposure to increasing BPA concentrations induced an oxidative stress in Picocystis cells, as evidenced by increased malondialdehyde content and the over-expression of antioxidant activities (ascorbate peroxydase, gluthation-S-transferase and catalase). Picocystis exhibited high BPA removal efficiency, reaching 72% and 40% at 25 and 75 mg L -1 BPA. BPA removal was ensured mainly by biodegradation/biotransformation processes. Based on these results, the extended tolerance and the high removal ability of Picocystis make her a promising specie for use in BPA bioremediation. Copyright © 2018. Published by Elsevier Inc.

Heterotrophic nitrification and aerobic denitrification by Pseudomonas tolaasii Y-11 without nitrite accumulation during nitrogen conversion.

PubMed

He, Tengxia; Li, Zhenlun; Sun, Quan; Xu, Yi; Ye, Qing

2016-01-01

A hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was found to display high removal capabilities for heterotrophic nitrification with ammonium and for aerobic denitrification with nitrate or nitrite nitrogen. When strain Y-11 was cultivated for 4days at 15°C with the initial ammonium, nitrate and nitrite nitrogen concentrations of 209.62, 204.61 and 204.33mg/L (pH 7.2), the ammonium, nitrate and nitrite removal efficiencies were 93.6%, 93.5% and 81.9% without nitrite accumulation, and the corresponding removal rates reached as high as 2.04, 1.99 and 1.74mg/L/h, respectively. Additionally, ammonium was removed mainly during the simultaneous nitrification and denitrification process. All results demonstrate that P. tolaasii strain Y-11 has the particularity to remove ammonium, nitrate and nitrite nitrogen at low temperatures, which guarantees it for future application in winter wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Removal of arsenite by a microbial bioflocculant produced from swine wastewater.

PubMed

Guo, Junyuan; Chen, Cheng

2017-08-01

This paper focused on the production and characteristics of a bioflocculant by using swine wastewater and its application in removing arsenite from aqueous solution. A series of experimental parameters including bioflocculant dose, calcium ions concentration, and solution pH value on arsenite uptake were evaluated. Results have demonstrated that a bioflocculant of 3.11 g L -1 was achieved as the maximum yield after 60 h fermentation, with a main backbone of polysaccharides. Maximum arsenite removal efficiency of 99.2% can be reached by adding bioflocculant in two stages: 3 × 10 -3 % (w/w) in the 1.0 min's rapid mixing (180 rpm) and 2 × 10 -3 % (w/w) after 2.0 min's slow mixing (80 rpm) with pH value fixed at 7. Negative Gibbs free energy change (ΔG o ) indicated the spontaneous nature of arsenite removal. Arsenite was removed by the bioflocculant through bridging mechanisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

PubMed Central

Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

2012-01-01

In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution. PMID:22693485

Biological Cr(VI) removal using bio-filters and constructed wetlands.

PubMed

Michailides, Michail K; Sultana, Mar-Yam; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Vayenas, Dimitrios V

2013-01-01

The bioreduction of hexavalent chromium from aqueous solution was carried out using suspended growth and packed-bed reactors under a draw-fill operating mode, and horizontal subsurface constructed wetlands. Reactors were inoculated with industrial sludge from the Hellenic Aerospace Industry using sugar as substrate. In the suspended growth reactors, the maximum Cr(VI) reduction rate (about 2 mg/L h) was achieved for an initial concentration of 12.85 mg/L, while in the attached growth reactors, a similar reduction rate was achieved even with high initial concentrations (109 mg/L), thus confirming the advantage of these systems. Two horizontal subsurface constructed wetlands (CWs) pilot-scale units were also built and operated. The units contained fine gravel. One unit was planted with common reeds and one was kept unplanted. The mean influent concentrations of Cr(VI) were 5.61 and 5.47 mg/L for the planted and unplanted units, respectively. The performance of the planted CW units was very effective as mean Cr(VI) removal efficiency was 85% and efficiency maximum reached 100%. On the contrary, the unplanted CW achieved very low Cr(VI) removal with a mean value of 26%. Both attached growth reactors and CWs proved efficient and viable means for Cr(VI) reduction.

[Electrochemically reductive dechlorination of chloroform in aqueous medium by codeposited palladium-nickel glassy carbon as cathode].

PubMed

Sun, Zhi-Rong; Li, Bao-Hua; Hu, Xiang; Shi, Min; Peng, Yong-Zhen

2008-05-01

The electrochemical deposition behaviors of Pd-Ni bimetal on glassy carbon (GC) electrode were studied by means of cyclic voltammetry (CV) based on orthogonal experiments. CV results reveal that Pd-Ni bimetal shows larger hydrogen adsorption peak than that of single Pd or Ni. The mixture of Ni2+ and Pd2+ can get hydrogen adsorption peak of -24.83 mA at - 500 mV (vs Hg/Hg2SO4). Scanning Electron Microscope (SEM) images reveal that nickel addition changes the distributing configuration of Pd microparticles on GC. And the appearance of Pd-Ni bimetal microparticles is distinctly different from that of single Pd and single Ni microparticles. Diameter of Pd-Ni microparticle is bigger than that of Pd microparticle and smaller than that of Ni microparticle. Effects of dechlorination current and time on removal efficiency of chloroform were also studied. The removal efficiency of chloroform increases at higher dechlorination current and longer dechlorination time. It reaches 42.53% when the dechlorination current and time are 0.5 mA and 180 min respectively on Pd-Ni/GC electrode prepared at optimum conditions. It can be envisioned that the removal efficiency of chloroform would increase further at longer dechlorination time.

Performance study of biofilter developed to treat H2S from wastewater odour

PubMed Central

Omri, Ilhem; Aouidi, Fethia; Bouallagui, Hassib; Godon, Jean-Jacques; Hamdi, Moktar

2013-01-01

Biofiltration is an efficient biotechnological process used for waste gas abatement in various industrial processes. It offers low operating and capital costs and produces minimal secondary waste streams. The objective of this study was to evaluate the performance of a pilot scale biofilter in terms of pollutants’ removal efficiencies and the bacterial dynamics under different inlet concentrations of H2S. The treatment of odourous pollutants by biofiltration was investigated at a municipal wastewater treatment plant (WWTP) (Charguia, Tunis, Tunisia). Sampling and analyses were conducted for 150 days. Inlet H2S concentration recorded was between 200 and 1300 mg H2S.m−3. Removal efficiencies reached 99% for the majority of the running time at an empty bed retention time (EBRT) of 60 s. Heterotrophic bacteria were found to be the dominant microorganisms in the biofilter. The bacteria were identified as the members of the genus Bacillus, Pseudomonas and xanthomonadacea bacterium. The polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) method showed that bacterial community profiles changed with the H2S inlet concentration. Our results indicated that the biofilter system, containing peat as the packing material, was proved able to remove H2S from the WWTP odourous pollutants. PMID:23961233

Experience from start-ups of the first ANITA Mox plants.

PubMed

Christensson, M; Ekström, S; Andersson Chan, A; Le Vaillant, E; Lemaire, R

2013-01-01

ANITA™ Mox is a new one-stage deammonification Moving-Bed Biofilm Reactor (MBBR) developed for partial nitrification to nitrite and autotrophic N-removal from N-rich effluents. This deammonification process offers many advantages such as dramatically reduced oxygen requirements, no chemical oxygen demand requirement, lower sludge production, no pre-treatment or requirement of chemicals and thereby being an energy and cost efficient nitrogen removal process. An innovative seeding strategy, the 'BioFarm concept', has been developed in order to decrease the start-up time of new ANITA Mox installations. New ANITA Mox installations are started with typically 3-15% of the added carriers being from the 'BioFarm', with already established anammox biofilm, the rest being new carriers. The first ANITA Mox plant, started up in 2010 at Sjölunda wastewater treatment plant (WWTP) in Malmö, Sweden, proved this seeding concept, reaching an ammonium removal rate of 1.2 kgN/m³ d and approximately 90% ammonia removal within 4 months from start-up. This first ANITA Mox plant is also the BioFarm used for forthcoming installations. Typical features of this first installation were low energy consumption, 1.5 kW/NH4-N-removed, low N₂O emissions, <1% of the reduced nitrogen and a very stable and robust process towards variations in loads and process conditions. The second ANITA Mox plant, started up at Sundets WWTP in Växjö, Sweden, reached full capacity with more than 90% ammonia removal within 2 months from start-up. By applying a nitrogen loading strategy to the reactor that matches the capacity of the seeding carriers, more than 80% nitrogen removal could be obtained throughout the start-up period.

Experimental Study on Ultrafine Particle Removal Performance of Portable Air Cleaners with Different Filters in an Office Room

PubMed Central

Ma, Huan; Shen, Henggen; Shui, Tiantian; Li, Qing; Zhou, Liuke

2016-01-01

Size- and time-dependent aerodynamic behaviors of indoor particles, including PM1.0, were evaluated in a school office in order to test the performance of air-cleaning devices using different filters. In-situ real-time measurements were taken using an optical particle counter. The filtration characteristics of filter media, including single-pass efficiency, volume and effectiveness, were evaluated and analyzed. The electret filter (EE) medium shows better initial removal efficiency than the high efficiency (HE) medium in the 0.3–3.5 μm particle size range, while under the same face velocity, the filtration resistance of the HE medium is several times higher than that of the EE medium. During service life testing, the efficiency of the EE medium decreased to 60% with a total purifying air flow of 25 × 104 m3/m2. The resistance curve rose slightly before the efficiency reached the bottom, and then increased almost exponentially. The single-pass efficiency of portable air cleaner (PAC) with the pre-filter (PR) or the active carbon granule filter (CF) was relatively poor. While PAC with the pre-filter and the high efficiency filter (PR&HE) showed maximum single-pass efficiency for PM1.0 (88.6%), PAC with the HE was the most effective at removing PM1.0. The enhancement of PR with HE and electret filters augmented the single-pass efficiency, but lessened the airflow rate and effectiveness. Combined with PR, the decay constant of large-sized particles could be greater than for PACs without PR. Without regard to the lifetime, the electret filters performed better with respect to resource saving and purification improvement. A most penetrating particle size range (MPPS: 0.4–0.65 μm) exists in both HE and electret filters; the MPPS tends to become larger after HE and electret filters are combined with PR. These results serve to provide a better understanding of the indoor particle removal performance of PACs when combined with different kinds of filters in school office buildings. PMID:26742055

Removal and biodegradation of different petroleum hydrocarbons using the filamentous fungus Aspergillus sp. RFC-1.

PubMed

Al-Hawash, Adnan B; Zhang, Xiaoyu; Ma, Fuying

2018-03-25

Petroleum pollution inevitably occurs at any stage of oil production and exerts a negative impact on the environment. Some microorganisms can degrade petroleum hydrocarbons (PHs). Polluted sludge of Rumaila oil field was use to isolate the highly efficient hydrocarbon-degrading fungal strain. Aspergillus sp. RFC-1 was obtained and its degradation ability for petroleum hydrocarbons was evaluated through surface adsorption, cell uptake, hydrophobicity, surface tension, biosurfactant production, and emulsification activity. In addition, the degradation mechanism was investigated. The results indicated the strain RFC-1 showed high removal activity for PHs, including biodegradation, adsorption, and emulsifiability. On the day 7 of incubation, the removal efficiencies of crude oil, naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR) reached 60.3%, 97.4%, 84.9%, and 90.7%, respectively. Biodegradation efficiencies of crude oil, NAP, PHE, and PYR were 51.8%, 84.6%, 50.3%, and 55.1%, respectively. Surface adsorption and cell absorption by live mycelial pellets followed a decreasing order: PYR ≥ PHE > NAP > crude oil. Adsorption by heat-killed mycelial pellets increased within 40 and 10 min for crude oil and PAHs, respectively, and remained constant thereafter. Effects of cell surface hydrophobicity, surface tension, and emulsification index were discussed. Intra- and extracellular enzymes of strain RFC-1 played important roles in PHs degradation. The strain RFC-1 is a prospective strain for removing PHs from aqueous environments. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Pilot plant demonstration of stable and efficient high rate biological nutrient removal with low dissolved oxygen conditions.

PubMed

Keene, Natalie A; Reusser, Steve R; Scarborough, Matthew J; Grooms, Alan L; Seib, Matt; Santo Domingo, Jorge; Noguera, Daniel R

2017-09-15

Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, recent research has shown that nitrification can be maintained using very low-DO concentrations (e.g., below 0.2 mg O 2 /L), and therefore, it may be possible to reduce energy use and costs in BNR facilities by decreasing aeration. However, the effect of reduced aeration on enhanced biological phosphorus removal (EBPR) is not understood. In this study, we investigated, at the pilot-scale level, the effect of using minimal aeration on the performance of an EBPR process. Over a 16-month operational period, we performed stepwise decreases in aeration, reaching an average DO concentration of 0.33 mg O 2 /L with stable operation and nearly 90% phosphorus removal. Under these low-DO conditions, nitrification efficiency was maintained, and nearly 70% of the nitrogen was denitrified, without the need for internal recycling of high nitrate aeration basin effluent to the anoxic zone. At the lowest DO conditions used, we estimate a 25% reduction in energy use for aeration compared to conventional BNR operation. Our improved understanding of the efficiency of low-DO BNR contributes to the global goal of reducing energy consumption during wastewater treatment operations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Decomposition of dimethylamine gas with dielectric barrier discharge.

PubMed

Ye, Zhaolian; Zhao, Jie; Huang, Hong ying; Ma, Fei; Zhang, Renxi

2013-09-15

The decomposition of dimethylamine (DMA) with gas under high flow rate was investigated with dielectric barrier discharge (DBD) technology. Different parameters including removal efficiency, energy yield, carbon balance and CO2 selectivity, secondary products, as well as pathways and mechanisms of DMA degradation were studied. The experimental results showed that removal efficiency of DMA depended on applied voltage and gas flow rate, but had no obvious correlation with initial concentration. Excellent energy performance was obtained using present DBD technology for DMA abatement. When experiment conditions were controlled at: gas flow rate of 14.9 m(3)/h, initial concentration of 2104 mg/m(3), applied voltage of 4.8 kV, removal efficiency of DMA and energy yield can reach 85.2% and 953.9 g/kWh, respectively. However, carbon balance (around 40%) was not ideal due to shorter residence time (about 0.1s), implying that some additional conditions should be considered to improve the total oxidation of DMA. Moreover, secondary products in outlet gas stream were detected via gas chromatogram-mass spectrum and the amounts of NO3(-) and NO2(-) were analyzed by ion chromatogram. The obtained data demonstrated that NOx might be suppressed due to reductive NH radical form DMA dissociation. The likely reaction pathways and mechanisms for the removal of DMA were suggested based on products analysis. Experimental results demonstrated the application potential of DBD as a clean technology for organic nitrogen-containing gas elimination from gas streams. Copyright © 2013 Elsevier B.V. All rights reserved.

Investigation of Removal Capacities of Biofilters for Airborne Viable Micro-Organisms

PubMed Central

Soret, Rémi; Fanlo, Jean-Louis; Malhautier, Luc; Geiger, Philippe; Bayle, Sandrine

2018-01-01

New emerging issues appears regarding the possible aerosolization of micro-organisms from biofilters to the ambient air. Traditional bioaerosol sampling and cultural methods used in literature offer relative efficiencies. In this study, a new method revolving around a particle counter capable of detecting total and viable particles in real time was used. This counter (BioTrak 9510-BD) uses laser-induced fluorescence (LIF) technology to determine the biological nature of the particle. The concentration of viable particles was measured on two semi-industrial pilot scale biofilters in order to estimate the Removal Efficiency in viable particles (REvp) in stable conditions and to examine the influence of pollutant feeding and relative humidification of the gaseous effluent on the REvp. The REvp of biofilters reached near 80% and highlighted both the stability of that removal and the statistical equivalence between two identical biofilters. Pollutant deprivation periods of 12 h, 48 h and 30 days were shown to have no influence on the biofilters’ removal capacity, demonstrating the robustness and adaptation capacities of the flora. In contrast, a 90-day famine period turned the biofilters into emitters of viable particles. Finally, the humidification of the effluent was shown to negatively influence the removal capacity for viable particles, as drying off the air was shown to increase the REvp from 60 to 85%. PMID:29562709

Improvement of sludge dewaterability and removal of sludge-borne metals by bioleaching at optimum pH.

PubMed

Liu, Fenwu; Zhou, Lixiang; Zhou, Jun; Song, Xingwei; Wang, Dianzhan

2012-06-30

Bio-acidification caused by bio-oxidation of energy substances during bioleaching is widely known to play an important role in improving sludge-borne metals removal. Here we report that bioleaching also drastically enhances sludge dewaterability in a suitable pH level. To obtain the optimum initial concentrations of energy substances and pH values for sludge dewaterability during bioleaching, bio-oxidation of Fe(2+) and S(0) under co-inoculation with Acidithiobacillus thiooxidans TS6 and Acidothiobacillus ferrooxidans LX5 and their effects on sludge dewaterability and metals removal during sludge bioleaching were investigated. Results indicated that the dosage of energy substances with 2g/L S(0) and 2g/L Fe(2+) could obtain bio-oxidation efficiencies of up to 100% for Fe(2+) and 50% for S(0) and were the optimal dosages for sludge bioleaching. The removal efficiencies of sludge-borne Cu and Cr could reach above 85% and 40%, respectively, and capillary suction time (CST) of bioleached sludge decreased to as low as ∼10s from initial 48.9s for fresh sludge when sludge pH declined to ∼2.4 through bioleaching. These results confirm the potential of bioleaching as a novel method for improving sludge dewaterability as well as removal of metals. Copyright © 2012 Elsevier B.V. All rights reserved.

Removal of persistent organic pollutants from micro-polluted drinking water by triolein embedded absorbent.

PubMed

Liu, Huijuan; Ru, Jia; Qu, Jiuhui; Dai, Ruihua; Wang, Zijian; Hu, Chun

2009-06-01

A new biomimetic absorbent, cellulose acetate (CA) embedded with triolein (CA-triolein), was prepared and applied for the removal of persistent organic pollutants (POPs) from micro-polluted aqueous solution. The comparison of CA-triolein, CA and granular activated carbon (GAC) for dieldrin removal was investigated. Results showed that CA-triolein absorbent gave a lowest residual concentration after 24 h although GAC had high removal rate in the first 4 h adsorption. Then the removal efficiency of mixed POPs (e.g. aldrin, dieldrin, endrin and heptachlor epoxide), absorption isotherm, absorbent regeneration and initial column experiments of CA-triolein were studied in detail. The linear absorption isotherm and the independent absorption in binary isotherm indicated that the selected POPs are mainly absorbed onto CA-triolein absorbent by a partition mechanism. The absorption constant, K, was closely related to the hydrophobic property of the compound. Thermodynamic calculations showed that the absorption was spontaneous, with a high affinity and the absorption was an endothermic reaction. Rinsing with hexane the CA-triolein absorbent can be regenerated after absorption of POPs. No significant decrease in the dieldrin removal efficiency was observed even when the absorption-regeneration process was repeated for five times. The results of initial column experiments showed that the CA-triolein absorbent did not reach the breakthrough point at a breakthrough empty-bed volume (BV) of 3200 when the influent concentration was 1-1.5 microg/L and the empty-bed contact time (EBCT) was 20 min.

Intensification of UV-C tertiary treatment: Disinfection and removal of micropollutants by sulfate radical based Advanced Oxidation Processes.

PubMed

Rodríguez-Chueca, J; García-Cañibano, C; Lepistö, R-J; Encinas, Á; Pellinen, J; Marugán, J

2018-04-21

This study explores the enhancement of UV-C tertiary treatment by sulfate radical based Advanced Oxidation Processes (SR-AOPs), including photolytic activation of peroxymonosulfate (PMS) and persulfate (PS) and their photocatalytic activation using Fe(II). Their efficiency was assessed both for the inactivation of microorganisms and the removal or micropollutants (MPs) in real wastewater treatment plant effluents. Under the studied experimental range (UV-C dose 5.7-57 J/L; UV-C contact time 3 to 28 s), the photolysis of PMS and PS (0.01 mM) increased up to 25% the bacterial removal regarding to UV-C system. The photolytic activation of PMS led to the total inactivation of bacteria (≈ 5.70 log) with the highest UV-C dose (57 J/L). However, these conditions were insufficient to remove the MPs, being required oxidant's dosages of 5 mM to remove above 90% of carbamazepine, diclofenac, atenolol and triclosan. The best efficiencies were achieved by the combination of PMS or PS with Fe(II), leading to the total removal of the MPs using a low UV-C dosage (19 J/L), UV-C contact time (9 s) and reagent's dosages (0.5 mM). Finally, high mineralization was reached (>50%) with photocatalytic activation of PMS and PS even with low reagent's dosages. Copyright © 2018 Elsevier B.V. All rights reserved.

High-accuracy process based on the corrective calibration of removal function in the magnetorheological finishing

NASA Astrophysics Data System (ADS)

Zhong, Xianyun; Fan, Bin; Wu, Fan

2017-08-01

The corrective calibration of the removal function plays an important role in the magnetorheological finishing (MRF) high-accuracy process. This paper mainly investigates the asymmetrical characteristic of the MRF removal function shape and further analyzes its influence on the surface residual error by means of an iteration algorithm and simulations. By comparing the ripple errors and convergence ratios based on the ideal MRF tool function and the deflected tool function, the mathematical models for calibrating the deviation of horizontal and flowing directions are presented. Meanwhile, revised mathematical models for the coordinate transformation of an MRF machine is also established. Furthermore, a Ø140-mm fused silica plane and a Ø196 mm, f/1∶1, fused silica concave sphere samples are taken as the experiments. After two runs, the plane mirror final surface error reaches PV 17.7 nm, RMS 1.75 nm, and the polishing time is 16 min in total; after three runs, the sphere mirror final surfer error reaches RMS 2.7 nm and the polishing time is 70 min in total. The convergence ratios are 96.2% and 93.5%, respectively. The spherical simulation error and the polishing result are almost consistent, which fully validate the efficiency and feasibility of the calibration method of MRF removal function error using for the high-accuracy subaperture optical manufacturing.

Efficient Degradation of Malathion in the Presence of Detergents Using an Engineered Organophosphorus Hydrolase Highly Expressed by Pichia pastoris without Methanol Induction.

PubMed

Bai, Yun-Peng; Luo, Xiao-Jing; Zhao, Yu-Lian; Li, Chun-Xiu; Xu, Dian-Sheng; Xu, Jian-He

2017-10-18

The biodegradation of pesticides by organophosphorus hydrolases (OPHs) requires an efficient enzyme production technology in industry. Herein, a Pichia pastoris strain was constructed for the extracellular expression of PoOPH M9 , an engineered malathion-degrading enzyme. After optimization, the maximum titer and yield of fermentation reached 50.8 kU/L and 4.1 g protein /L after 3 days, with the highest space-time yield (STY) reported so far, 640 U L -1 h -1 . PoOPH M9 displayed its high activity and stability in the presence of 0.1% (w/w) plant-derived detergent. Only 0.04 mg/mL enzyme could completely remove 0.15 mM malathion in aqueous solution within 20 min. Furthermore, 12 μmol malathion on apples and cucumbers surfaces was completely removed by 0.05 mg/mL PoOPH M9 in tap water after 35 min washing. The efficient production of the highly active PoOPH M9 has cleared a major barrier to biodegradation of pesticide residues in food industry.

Application of biofiltration to the degradation of hydrogen sulfide in gas effluents.

PubMed

Elías, A; Barona, A; Ríos, F J; Arreguy, A; Munguira, M; Peñas, J; Sanz, J L

2000-01-01

A laboratory scale bioreactor has been designed and set up in order to degrade hydrogen sulfide from an air stream. The reactor is a vertical column of 7 litre capacity and 1 meter in height. It is divided into three modules and each module is filled with pellets of agricultural residues as packing bed material. The gas stream fed into the reactor through the upper inlet consists of a mixture of hydrogen sulfide and humidified air. The hydrogen sulfide content in the inlet gas stream was increased in stages until the degradation efficiency was below 90%. The parameters to be controlled in order to reach continuous and stable operation were temperature, moisture content and the percentage of the compound to be degraded at the inlet and outlet gas streams (removal or elimination efficiency). When the H2S mass loading rate was between 10 and 40 g m(-3) h(-1), the removal efficiency was greater than 90%. The support material had a good physical performance throughout operation time, which is evidence that this material is suitable for biofiltration purposes.

Biodegradation of crude oil using an efficient microbial consortium in a simulated marine environment.

PubMed

Bao, Mu-tai; Wang, Li-na; Sun, Pei-yan; Cao, Li-xin; Zou, Jie; Li, Yi-ming

2012-06-01

Ochrobactrum sp. N1, Brevibacillus parabrevis N2, B. parabrevis N3 and B. parabrevis N4 were selected when preparing a mixed bacterial consortium based on the efficiency of crude oil utilization. A crude oil degradation rate of the N-series microbial consortium reached upwards of 79% at a temperature of 25 °C in a 3.0% NaCl solution in the shake flask trial. In the mesocosm experiment, a specially designed device was used to simulate the marine environment. The internal tank size was 1.5 m (L)×0.8 m (W)×0.7 m (H). The microbial growth conditions, nutrient utilization and environmental factors were thoroughly investigated. Over 51.1% of the crude oil was effectively removed from the simulated water body. The escalation process (from flask trials to the mesocosm experiment), which sought to represent removal under conditions more similar to the field, proved the high efficiency of using N-series bacteria in crude oil degradation. Copyright © 2012 Elsevier Ltd. All rights reserved.

A hybrid absorption–adsorption method to efficiently capture carbon

PubMed Central

Liu, Huang; Liu, Bei; Lin, Li-Chiang; Chen, Guangjin; Wu, Yuqing; Wang, Jin; Gao, Xueteng; Lv, Yining; Pan, Yong; Zhang, Xiaoxin; Zhang, Xianren; Yang, Lanying; Sun, Changyu; Smit, Berend; Wang, Wenchuan

2014-01-01

Removal of carbon dioxide is an essential step in many energy-related processes. Here we report a novel slurry concept that combines specific advantages of metal-organic frameworks, ion liquids, amines and membranes by suspending zeolitic imidazolate framework-8 in glycol-2-methylimidazole solution. We show that this approach may give a more efficient technology to capture carbon dioxide compared to conventional technologies. The carbon dioxide sorption capacity of our slurry reaches 1.25 mol l−1 at 1 bar and the selectivity of carbon dioxide/hydrogen, carbon dioxide/nitrogen and carbon dioxide/methane achieves 951, 394 and 144, respectively. We demonstrate that the slurry can efficiently remove carbon dioxide from gas mixtures at normal pressure/temperature through breakthrough experiments. Most importantly, the sorption enthalpy is only −29 kJ mol−1, indicating that significantly less energy is required for sorbent regeneration. In addition, from a technological point of view, unlike solid adsorbents slurries can flow and be pumped. This allows us to use a continuous separation process with heat integration. PMID:25296559

Coupled Electrokinetics-Adsorption Technique for Simultaneous Removal of Heavy Metals and Organics from Saline-Sodic Soil

PubMed Central

Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

2013-01-01

In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils. PMID:24235885

Effective organics degradation from pharmaceutical wastewater by an integrated process including membrane bioreactor and ozonation.

PubMed

Mascolo, G; Laera, G; Pollice, A; Cassano, D; Pinto, A; Salerno, C; Lopez, A

2010-02-01

The enhanced removal of organic compounds from a pharmaceutical wastewater resulting from the production of an anti-viral drug (acyclovir) was obtained by employing a membrane bioreactor (MBR) and an ozonation system. An integrated MBR-ozonation system was set-up by placing the ozonation reactor in the recirculation stream of the MBR effluent. A conventional treatment set-up (ozonation as polishing step after MBR) was also used as a reference. The biological treatment alone reached an average COD removal of 99%, which remained unvaried when the ozonation step was introduced. An acyclovir removal of 99% was also obtained with the MBR step and the ozonation allowed to further remove 99% of the residual concentration in the MBR effluent. For several of the 28 organics identified in the wastewater the efficiency of the MBR treatment improved from 20% to 60% as soon as the ozonation was placed in the recirculation stream. The benefit of the integrated system, with respect to the conventional treatment set-up was evident for the removal of a specific ozonation by-product. The latter was efficiently removed in the integrated system, being its abundance in the final effluent 20-fold lower than what obtained when ozonation was used as a polishing step. In addition, if the conventional treatment configuration is employed, the same performance of the integrated system in terms of by-product removal can only be obtained when the ozonation is operated for longer than 60 min. This demonstrates the effectiveness of the integrated system compared to the conventional polishing configuration. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Biofiltration technology for the removal of toluene from polluted air using Streptomyces griseus.

PubMed

Mohamed, Elham F; Awad, Gamal; Andriantsiferana, Caroline; El-Diwany, Ahmed I

2016-01-01

Biofiltration technology has been recognized as a promising biotechnology for treating the volatile organic compounds (VOCs) present in polluted air. This study aims to investigate the performance of a biofiltration system of Streptomyces griseus sp. DSM-40759 immobilized on activated carbon (PICA S23) towards the adsorption and degradation of toluene vapour as well as to regenerate the activated carbon in situ. The batch studies were performed using nutrient agar medium and basal salt medium (BSM) for microbial growth. Initially the pre-cultures were incubated at a temperature of 28°C on a rotary shaker at 150 rpm. After two days, the strain S. griseus DSM-40759 was immobilized on a known weight of activated carbon (12 g). The results of biofilter performance showed three different stages with a quick adsorption phase with approximately 95% of toluene removal after 70 min, a slow biotransformation phase by immobilized cells. In the later, the removal efficiency decreased significantly with the extension of time and reached 60% during this stage. Moreover, a final quick removal phase by the immobilized cells had an average removal efficiency of toluene around 95% after 500 min. The toluene degradation was found to be more than 84% after the second cycle and the biofilter was still capable of removing additional toluene. Thus, the results demonstrated the feasibility and reusability of a new biofilter system for toluene removal as well as extending the activated carbon's capacity and this could be a potential solution to reuse the activated carbon in industrial application.

Investigation on the Room-temperature preparation of Cobalt hybrid/Graphene Nanocomposite and application in wastewater purification: Highly Efficient Removal of Congo Red

NASA Astrophysics Data System (ADS)

Wang, L. X.; Zhao, Y. F.; Meng, Q. M.

2018-01-01

Here, we are going to report a simple, low-cost and environmental friendly process to prepare the cobalt hybrid/graphene (Co/G) nanocomposite at room temperature. NaBH4 was used as the reducing agent. Such an approach can be extended to grow some other metal/G nanocomposites, for example, Ni/G, Co/G nanocomposite possesses narrow size-distribution and good dispersion. Because of the special appearance with large surface area, and the special synthesis process of the productions, adsorption experiments for Congo Red were carried out in synthetic wastewater. The CR removal ability of Co/G nanocomposite can reach 263.2 mg/g.

Removal of several pesticides in a falling water film DBD reactor with activated carbon textile: Energy efficiency.

PubMed

Vanraes, Patrick; Ghodbane, Houria; Davister, Dries; Wardenier, Niels; Nikiforov, Anton; Verheust, Yannick P; Van Hulle, Stijn W H; Hamdaoui, Oualid; Vandamme, Jeroen; Van Durme, Jim; Surmont, Pieter; Lynen, Frederic; Leys, Christophe

2017-06-01

Bio-recalcitrant micropollutants are often insufficiently removed by modern wastewater treatment plants to meet the future demands worldwide. Therefore, several advanced oxidation techniques, including cold plasma technology, are being investigated as effective complementary water treatment methods. In order to permit industrial implementation, energy demand of these techniques needs to be minimized. To this end, we have developed an electrical discharge reactor where water treatment by dielectric barrier discharge (DBD) is combined with adsorption on activated carbon textile and additional ozonation. The reactor consists of a DBD plasma chamber, including the adsorptive textile, and an ozonation chamber, where the DBD generated plasma gas is bubbled. In the present paper, this reactor is further characterized and optimized in terms of its energy efficiency for removal of the five pesticides α-HCH, pentachlorobenzene, alachlor, diuron and isoproturon, with initial concentrations ranging between 22 and 430 μg/L. Energy efficiency of the reactor is found to increase significantly when initial micropollutant concentration is decreased, when duty cycle is decreased and when oxygen is used as feed gas as compared to air and argon. Overall reactor performance is improved as well by making it work in single-pass operation, where water is flowing through the system only once. The results are explained with insights found in literature and practical implications are discussed. For the used operational conditions and settings, α-HCH is the most persistent pesticide in the reactor, with a minimal achieved electrical energy per order of 8 kWh/m 3 , while a most efficient removal of 3 kWh/m 3 or lower was reached for the four other pesticides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multiyear Downstream Response to Dam Removal on the White Salmon River, WA

NASA Astrophysics Data System (ADS)

Wilcox, A. C.; O'Connor, J. E.; Major, J. J.

2017-12-01

The 2011 removal of the 38 m tall Condit Dam on the White Salmon River, Washington was one of the largest dam removals to date, in terms of both dam height and sediment release. We examined the multiyear geomorphic response to this event, through 2015, including in a bedrock-confined canyon and in a less-confined, backwater-influenced pool reach near the river's mouth, to the large, rapid influx of fine reservoir sediment produced by the breach and to subsequent sediment transfer in the free-flowing White Salmon River. In the canyon reach, aggraded sediments were rapidly eroded from riffles, returning them toward pre-breach bed elevations within weeks, but pool aggradation persisted for longer. The downstream, less-confined reach transformed from a deep pool to a narrower pool-riffle channel with alternate bars; multiyear observations showed persistence of bars and of this new and distinct morphology. This downstream reach marks a rare case in post-dam removal channel response; in most dam removals, channels have rapidly reverted toward pre-removal morphology, as in the canyon reach here. Comparison of the multiyear geomorphic evolution of the White Salmon River to other recent large dam removals in the U.S. allows evaluation of the relative influences of antecedent channel morphology, post-breach hydrology, and dam removal style, as well as providing a basis for predicting responses to future dam removals.

Improved Nitrogen Removal Effect In Continuous Flow A2/O Process Using Typical Extra Carbon Source

NASA Astrophysics Data System (ADS)

Wu, Haiyan; Gao, Junyan; Yang, Dianhai; Zhou, Qi; Cai, Bijing

2010-11-01

In order to provide a basis for optimal selection of carbon source, three typical external carbon sources (i.e. methanol, sodium acetate and leachate) were applied to examine nitrogen removal efficiency of continuous flow A2/O system with the influent from the effluent of grit chamber in the second Kunming wastewater treatment plant. The best dosage was determined, and the specific nitrogen removal rate and carbon consumption rate were calculated with regard to individual external carbon source in A2/O system. Economy and technology analysis was also conducted to select the suitable carbon source with a low operation cost. Experimental results showed that the external typical carbon source caused a remarkable enhancement of system nitrate degradation ability. In comparison with the blank test, the average TN and NH3-N removal efficiency of system with different dosing quantities of external carbon source was improved by 15.2% and 34.2%, respectively. The optimal dosage of methanol, sodium acetate and leachate was respectively up to 30 mg/L, 40 mg/L and 100 mg COD/L in terms of a high nitrogen degradation effect. The highest removal efficiency of COD, TN and NH3-N reached respectively 92.3%, 73.9% and 100% with methanol with a dosage of 30 mg/L. The kinetic analysis and calculation revealed that the greatest denitrification rate was 0.0107 mg TN/mg MLVSSṡd with sodium acetate of 60 mg/L. As to carbon consumption rate, however, the highest value occurred in the blank test with a rate of 0.1955 mg COD/mg MLVSSṡd. Also, further economic analysis proved leachate to be pragmatic external carbon source whose cost was far cheaper than methanol.

Occurrence and Removal of Organic Micropollutants in Landfill Leachates Treated by Electrochemical Advanced Oxidation Processes.

PubMed

Oturan, Nihal; van Hullebusch, Eric D; Zhang, Hui; Mazeas, Laurent; Budzinski, Hélène; Le Menach, Karyn; Oturan, Mehmet A

2015-10-20

In recent years, electrochemical advanced oxidation processes have been shown to be an effective alternative for the removal of refractory organic compounds from water. This study is focused on the effective removal of recalcitrant organic matter (micropollutants, humic substances, etc.) present in municipal solid waste landfill leachates. A mixture of eight landfill leachates has been studied by the electro-Fenton process using a Pt or boron-doped diamond (BDD) anode and a carbon felt cathode or by the anodic oxidation process with a BDD anode. These processes exhibit great oxidation ability due to the in situ production of hydroxyl radicals ((•)OH), a highly powerful oxidizing species. Both electrochemical processes were shown to be efficient in the removal of dissolved total organic carbon (TOC) from landfill leachates. Regarding the electro-Fenton process, the replacement of the classical anode Pt by the anode BDD allows better performance in terms of dissolved TOC removal. The occurrence and removal yield of 19 polycyclic aromatic hydrocarbons, 15 volatile organic compounds, 7 alkylphenols, 7 polychlorobiphenyls, 5 organochlorine pesticides, and 2 polybrominated diphenyl ethers in landfill leachate were also investigated. Both electrochemical processes allow one to reach a quasicomplete removal (about 98%) of these organic micropollutants.

Emulsion Liquid Membrane Removal of Arsenic and Strontium from Wastewater: AN Experimental and Theoretical Study.

NASA Astrophysics Data System (ADS)

Zhou, Ding-Wei

The emulsion liquid membrane (ELM) technique has been successfully applied on the removal of arsenic (As) from metallurgical wastewater and the removal of strontium (Sr) from radioactive wastewater. This study consisted of experimental work and mathematical modeling. Extraction of arsenic by an emulsion liquid membrane was firstly investigated. The liquid membrane used was composed of 2-ethylhexyl alcohol (2EHA) as the extractant, ECA4360J as the surfactant, and Exxsol D-80 solvent (or heptane) as the diluent. The sulfuric acid and sodium hydroxide solutions were used as the external and internal phases, respectively. The arsenic removal efficiency reached 92% within 15 minutes in one stage. Extraction and stripping chemistries were postulated and investigated. It was observed that extraction efficiency and rate increase with the increase of acidic strength and alkali strength in the external and internal phases, respectively. It was also observed that the removal selectivity of arsenic over copper is extremely high. Strontium-90 is one of the major radioactive metals appearing in nuclear wastewater. The emulsion liquid membrane process was investigated as a separation method by using the non-radioactive ^{87}Sr as its substitute. In our study, the membrane phase was composed of di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant, ECA4360J as the surfactant and Exxsol D-80 as the diluent. A sulfuric acid solution was used in the internal phase as the stripping agent. The pH range in the external phase was determined by the extraction isotherm. Under the most favorable operating condition, the strontium removal efficiency can reach 98% in two minutes. Mass transfer of the emulsion liquid membrane (ELM) system was modeled mathematically. Our model took into account the following: mass transfer of solute across the film between the external phase and the membrane phase, chemical equilibrium of the extraction reaction at the external phase-membrane interface, simultaneous diffusion of the solute-carrier complex inside the globule membrane phase and stripping of the complex at the membrane-internal phase interface, chemical equilibrium of the stripping reaction at the membrane-internal phase interface and leakage of the solute from the internal phase to the external phase. Resulting simultaneous partial differential equations were solved analytically by the Laplace transform method. Four dimensionless groups were found with special physical meanings to characterize the emulsion liquid membrane systems. It not only predicted the concentration of solute in the external phase versus time, but also gave the concentration profile inside the membrane globule and the interfacial concentration at the external-membrane phase interface at different time. The model predicted very well the experimental data obtained from the removal of arsenic and strontium by the emulsion liquid membranes.

NH2Fe3O4@SiO2 supported peroxidase catalyzed H2O2 for degradation of endocrine disrupter from aqueous solution: Roles of active radicals and NOMs.

PubMed

Ai, Jing; Zhang, Weijun; Liao, Guiying; Xia, Hua; Wang, Dongsheng

2017-11-01

In this work, magnetic Fe 3 O 4 was utilized to immobilize horseradish peroxidase (IM-HRP) in order to improve its stability and reusability by crosslinking method process with glutaraldehyde. The physicochemical properties of NH 2 Fe 3 O 4 @SiO 2 and IM-HRP were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermo-gravimetric Analysis (TGA) and Transmission electron microscopy (TEM). The thermal stability of immobilized-HRP was considerably improved in comparison with free counterpart. The catalytic performance of IM-HRP for estrogens removal from aqueous solution was evaluated, it was found that the presence of natural organic matters (NOM) have no significant effects on E2 removal and the E2 enzyme-degradation reached around 80% when pH = 7.0 with 0.552 × 10 -3 ratio of IM-HRP/H 2 O 2. In addition, the active radicals responsible for estrogens degradation were identified with electro-spin resonance spectra (ESR). It was found that immobilization process on Fe 3 O 4 showed no adverse effects on catalytic performance on HRP, estrogens degradation could be fitted well with pseudo-second kinetic equation. Estrogens degradation efficiency was reduced in the presence of humic substances. Both O 2 - and OH were detected in IM-HRP catalyzed H 2 O 2 system and radicals quenching test indicated O 2 - played a more important role in estrogens removal. IM-HRP exhibited excellent stability and E2 removal efficiency could reach 45.41% after use seven times. Therefore, HRP enzymes immobilized on NH 2 Fe 3 O 4 @SiO 2 by cross-linking method in glutaraldehyde solutions was an effective way to improve stability and reusability of HRP, and which could avoid potential secondary pollution in water environment caused by free HRP after treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance and bacterial diversity of biotrickling filters filled with conductive packing material for the treatment of toluene.

PubMed

Wu, Hao; Guo, Chunyu; Yin, Zhenhao; Quan, Yue; Yin, Chengri

2018-06-01

Toluene has high toxicity and mutagenicity, thus, the removal of toluene from air is necessary. In this study, two biotrickling filters (BTFs) were constructed and packed with conductive packing material to treat toluene waste gas. BTF-O exhibited good toluene removal performance even under high toluene inlet concentration, and over 80% of removal efficiency was observed. The elimination capacity reached 120.1 g/m 3  h corresponding to an inlet concentration of 2.259 g/m 3 under 61.5 s of empty bed retention time. During toluene biodegradation, the output voltage was observed in BTF-O and BTF-E, moreover BTF-E also showed slight power storage capacity. The applied voltage inhibited toluene removal and affected the bacterial community. The predominant bacterial genera in BTF-O were Acidovorax, Rhodococcus, Hydrogenophaga, Brevundimonas, Arthrobacter, Pseudoxanthomonas, Devosia, Gemmobacter, Rhizobium, Dokdonella and Pseudomonas. Genera Xanthobacter and Pelomonas accounted for the main bacterial community in BTF-E. Copyright © 2018 Elsevier Ltd. All rights reserved.

A novel biodegradable β-cyclodextrin-based hydrogel for the removal of heavy metal ions.

PubMed

Huang, Zhanhua; Wu, Qinglin; Liu, Shouxin; Liu, Tian; Zhang, Bin

2013-09-12

A novel biodegradable β-cyclodextrin-based gel (CAM) was prepared and applied to the removal of Cd(2+), Pb(2+) and Cu(2+) ions from aqueous solutions. CAM hydrogel has a typical three-dimensional network structure, and showed excellent capability for the removal of heavy metal ions. The effect of different experimental parameters, such as initial pH, adsorbent dosage and initial metal ion concentration, were investigated. The adsorption isotherm data fitted well to the Freundlich model. The adsorption capacity was in the order Pb(2+)>Cu(2+)>Cd(2+) under the same experimental conditions. The maximum adsorption capacities for the metal ions in terms of mg/g of dry gel were 210.6 for Pb(2+), 116.41 for Cu(2+), and 98.88 for Cd(2+). The biodegradation efficiency of the resin reached 79.4% for Gloeophyllum trabeum. The high adsorption capacity and kinetics results indicate that CAM can be used as an alternative adsorbent to remove heavy metals from aqueous solution. Published by Elsevier Ltd.

Biomass and pigments production in photosynthetic bacteria wastewater treatment: effects of light sources.

PubMed

Zhou, Qin; Zhang, Panyue; Zhang, Guangming

2015-03-01

This study is aimed at enhancing biomass and pigments production together with pollution removal in photosynthetic bacteria (PSB) wastewater treatment via different light sources. Red, yellow, blue, white LED and incandescent lamp were used. Results showed different light sources had great effects on the PSB. PSB had the highest biomass production, COD removal and biomass yield with red LED. The corresponding biomass, COD removal and biomass yield reached 2580 mg/L, 88.6% and 0.49 mg-biomass/mg-COD-removal, respectively. The hydraulic retention time of wastewater treatment could be shortened to 72 h with red LED. Mechanism analysis showed higher ATP was produced with red LED than others. Light sources could significantly affect the pigments production. The pigments productions were greatly higher with LED than incandescent lamp. Yellow LED had the highest pigments production while red LED produced the highest carotenoid/bacteriochlorophyll ratio. Considering both efficiency and energy cost, red LED was the optimal light source. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nitrogen and phosphorus removal from tertiary wastewater in an osmotic membrane photobioreactor.

PubMed

Praveen, Prashant; Loh, Kai-Chee

2016-04-01

An osmotic membrane photobioreactor (OMPBR) was designed and operated for 162days for nitrogen and phosphorus removal from wastewater using Chlorella vulgaris. The removal efficiency for NH4(+)-N, NO3(-)-N and PO4(3-)-P reached as high as 95%, 53% and 89%, whereas the maximum removal rates were 3.41 mg/L-day, 0.20 mg/L-day and 0.8 mg/L-day, respectively. The microalgae exhibited high tendency to aggregate and attached to the bioreactor and membrane surfaces, and total biomass accumulation in the OMPBR was over 5 g/L. Salt accumulation and biofouling had adverse effects on membrane filtration, but the performance could be recovered through periodic backwashing of the membranes. Extracellular polymeric substances characterization indicated higher fraction of polysaccharides as compared to proteins. The biomass in the OMPBR accumulated higher levels of carbohydrates and chlorophyll. These results indicate the suitability of OMPBR in wastewater treatment and in high-density microalgae cultivation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Regeneration of sulfamethoxazole-saturated activated carbon using gamma irradiation

NASA Astrophysics Data System (ADS)

Chu, Libing; Wang, Jianlong

2017-01-01

Activated carbon (AC) has been widely used for reclamation and reuse of the effluent of wastewater treatment plant to further remove the emerging contaminants, such as PPCPs in recent years. How to regenerate the exhausted AC effectively and economically is still a challenge. In the present study, the regeneration of AC exhausted with SMX was performed by gamma irradiation to simultaneously recover the spent AC and degrade the pollutants. The results showed that the adsorption of SMX onto AC can be described by the Langmuir isotherm and the adsorption capacity was about 417 mg/g. SMX can be removed rapidly when exposed to gamma irradiation, with the initial concentration of 100 mg/L, more than 99% of SMX was removed at 5.0 kGy, while an extremely high dose (150 kGy) was needed to reach 80% mineralization ratio. The regeneration efficiency was about 21-30% at 50-200 kGy. The absorbed SMX and the intermediates formed during gamma irradiation were released into aqueous solution from AC and mineralized, leading to the partial regeneration of the adsorption capacity of AC. Further studies are needed to optimize the experimental conditions to increase the regeneration efficiency.

Electrokinetic remediation of manganese and ammonia nitrogen from electrolytic manganese residue.

PubMed

Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Du, Jun; Tao, Changyuan

2015-10-01

Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore, which mainly contains manganese and ammonia nitrogen and seriously damages the ecological environment. This work demonstrated the use of electrokinetic (EK) remediation to remove ammonia nitrogen and manganese from EMR. The transport behavior of manganese and ammonia nitrogen from EMR during electrokinetics, Mn fractionation before and after EK treatment, the relationship between Mn fractionation and transport behavior, as well as the effects of electrolyte and pretreatment solutions on removal efficiency and energy consumption were investigated. The results indicated that the use of H2SO4 and Na2SO4 as electrolytes and pretreatment of EMR with citric acid and KCl can reduce energy consumption, and the removal efficiencies of manganese and ammonia nitrogen were 27.5 and 94.1 %, respectively. In these systems, electromigration and electroosmosis were the main mechanisms of manganese and ammonia nitrogen transport. Moreover, ammonia nitrogen in EMR reached the regulated level, and the concentration of manganese in EMR could be reduced from 455 to 37 mg/L. In general, the electrokinetic remediation of EMR is a promising technology in the future.

Biodegradation characterization and immobilized strains' potential for quinoline degradation by Brevundimonas sp. K4 isolated from activated sludge of coking wastewater.

PubMed

Wang, Chunrong; Zhang, Mengru; Cheng, Fanglin; Geng, Qi

2015-01-01

A novel quinoline-degrading strain, named K4, was isolated from activated sludge of a coking wastewater treatment plant and identified as Brevundimonas sp. on the basis of its 16s rDNA gene sequence analysis. Its optimum temperature and pH for quinoline degradation were 30 °C and pH 9.0, respectively, and during the biodegradation process, at 100 mg/L initial quinoline concentration, an inoculation amount of 8% (OD600 of 0.23) was the optimal strain concentration. In addition, the kinetics of free K4 strains for quinoline degradation showed that it followed a zero-order equation. Furthermore, compared with free K4 strains, immobilized K4 strains' potential for quinoline degradation was investigated by adding both of them into SBR reactors for actual coking wastewater treatment on operation over 15 days. The results showed that bioaugmentation by both free and immobilized K4 strains enhanced quinoline removal efficiency, and especially, the latter could reach its stable removal after a shorter accommodation period, with 94.8% of mean quinoline removal efficiency.

Characteristics of back corona discharge in a honeycomb catalyst and its application for treatment of volatile organic compounds.

PubMed

Feng, Fada; Zheng, Yanyan; Shen, Xinjun; Zheng, Qinzhen; Dai, Shaolong; Zhang, Xuming; Huang, Yifan; Liu, Zhen; Yan, Keping

2015-06-02

The main technical challenges for the treatment of volatile organic compounds (VOCs) with plasma-assisted catalysis in industrial applications are large volume plasma generation under atmospheric pressure, byproduct control, and aerosol collection. To solve these problems, a back corona discharge (BCD) configuration has been designed to evenly generate nonthermal plasma in a honeycomb catalyst. Voltage-current curves, discharge images, and emission spectra have been used to characterize the plasma. Grade particle collection results and flow field visualization in the discharge zones show not only that the particles can be collected efficiently, but also that the pressure drop of the catalyst layer is relatively low. A three-stage plasma-assisted catalysis system, comprising a dielectric barrier discharge (DBD) stage, BCD stage, and catalyst stage, was built to evaluate toluene treatment performance by BCD. The ozone analysis results indicate that BCD enhances the ozone decomposition by collecting aerosols and protecting the Ag-Mn-O catalyst downstream from aerosol contamination. The GC and FTIR results show that BCD contributes to toluene removal, especially when the specific energy input is low, and the total removal efficiency reaches almost 100%. Furthermore, this removal results in the emission of fewer byproducts.

Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions.

PubMed

Mohamed, Alaa; Osman, T A; Toprak, M S; Muhammed, M; Uheida, A

2017-08-01

A novel composites nanofiber was synthesized based on PAN-CNT/TiO 2 -NH 2 nanofibers using electrospinning technique followed by chemical modification of TiO 2 NPs. PAN-CNT/TiO 2 -NH 2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Paracetamol and salicylic acid removal from contaminated water by microalgae.

PubMed

Escapa, C; Coimbra, R N; Paniagua, S; García, A I; Otero, M

2017-12-01

The biomass growth, pharmaceutical removal and light conversion efficiency of Chlorella sorokiniana under the presence of paracetamol (PC) and salicylic acid (SaC) were assessed and compared at two different concentrations of these pharmaceuticals (I: 25 mg l -1 , II: 250 mg l -1 ). Microalgae were resistant to these concentrations and, moreover, their growth was significantly stimulated (p ≤ 0.05) under these drugs (biomass concentration increased above 33% PCI, 35% SaCI, 13% PCII and 45% SaCII, as compared with the respective positive controls). At the steady state of the semicontinuous culture, C. sorokiniana showed removal efficiencies above 41% and 69% for PCI and PCII, respectively; and above 93% and 98% for SaCI and SaCII, respectively. Under an irradiance of 370 μE m -2  s -1 , higher quantum yields were reached by microalgae under the presence of drugs, either at dose I or II, than by the respective positive controls. These results point to C. sorokiniana as a robust strain for the bioremediation of paracetamol and salicylic acid concentrated wastewaters. Copyright © 2016 Elsevier Ltd. All rights reserved.

A novel carboxyl-rich chitosan-based polymer and its application for clay flocculation and cationic dye removal.

PubMed

Liu, Bingzhi; Zheng, Huaili; Wang, Yili; Chen, Xin; Zhao, Chuanliang; An, Yanyan; Tang, Xiaomin

2018-05-30

Due to the complexity of contaminants, the effectiveness of traditional flocculants toward water purification is insufficient. To break the limitation, a novel polymer flocculant [chitosan grafted poly (acrylamide-itaconic acid), CS-g-P(AM-IA)] was synthesized via ultraviolet-initiated graft copolymerization reaction. Characterization results revealed that the graft copolymers were successfully synthesized and with rougher surface structure. The solubility of CS-g-P(AM-IA) and chitosan grafted polyacrylamide (CS-g-PAM) were greatly improved and they can dissolve in the wide pH range of 2.0-12.0. CaCl 2 was used as a source of cation bridge to enhance the flocculation of kaolin particles, and its optimum dosage was 150 mg·L -1 . At dosage of 30 mg·L -1 and pH of 5.0, the turbidity removal efficiency of CS-g-P(AM-IA) reached the maximum of 93.8%, whereas those of CS-g-PAM and CS were 96.7% and 76.9%, respectively. The patchwise adsorption of ionic groups embedded in the molecular chain on Ca 2+ -clay complexes took effect to generate flocs with larger particle size. Besides, the decolorization ability of cationic dyes by CS-g-P(AM-IA) was greatly enhanced due to the role of abundant carboxyl groups. In the crystal violet (CV) adsorption experiment, the maximum CV dye removal efficiency for CS-g-P(AM-IA) reached the maximum of 81.6% at dosage of 0.7 mg·mL -1 and pH of 9.0, while those for CS-g-PAM and CS were 51.7% and 36.5%, respectively. Copyright © 2018. Published by Elsevier B.V.

Integrating anammox with the autotrophic denitrification process via electrochemistry technology.

PubMed

Qiao, Sen; Yin, Xin; Zhou, Jiti; Wei, Li'e; Zhong, Jiayou

2018-03-01

In this study, an autotrophic denitrification process was successfully coupled with anammox to remove the nitrate by-product via electrochemical technology. When the voltage applied to the combined electrode reactor was 1.5 V, the electrode reaction removed nitrate by using the autotrophic denitrification biomass without affecting the anammox biomass. The nitrogen removal efficiency of the combined electrode reactor reached 99.1% without detectable nitrate at an influent NO 2 - -N/NH 4 + -N ratio of 1.5. On day 223, using the model calculations based on reaction equations, 19.7% of total nitrogen was removed via the autotrophic denitrification process, while the majority of nitrogen removal (approximately 79.4%) was attributed to the anammox reaction. Small variations of the population numbers and community structure of artificial bacteria according to electron microscopy predicted that the anammox and autotrophic denitrifying biomasses could coexist in the electrode reactor. Then, 16S rRNA analysis determined that the anammox biomass group was always dominant in mixed flora during continuous cultivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microbial monitoring of ammonia removal in a UASB reactor treating pre-digested chicken manure with anaerobic granular inoculum.

PubMed

Yangin-Gomec, Cigdem; Pekyavas, Goksen; Sapmaz, Tugba; Aydin, Sevcan; Ince, Bahar; Akyol, Çağrı; Ince, Orhan

2017-10-01

Performance and microbial community dynamics in an upflow anaerobic sludge bed (UASB) reactor coupled with anaerobic ammonium oxidizing (Anammox) treating diluted chicken manure digestate (Total ammonia nitrogen; TAN=123±10mg/L) were investigated for a 120-d operating period in the presence of anaerobic granular inoculum. Maximum TAN removal efficiency reached to above 80% with as low as 20mg/L TAN concentrations in the effluent. Moreover, total COD (tCOD) with 807±215mg/L in the influent was removed by 60-80%. High-throughput sequencing revealed that Proteobacteria, Actinobacteria, and Firmicutes were dominant phyla followed by Euryarchaeota and Bacteroidetes. The relative abundance of Planctomycetes significantly increased from 4% to 8-9% during the late days of the operation with decreased tCOD concentration, which indicated a more optimum condition to favor ammonia removal through anammox route. There was also significant association between the hzsA gene and ammonia removal in the UASB reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cultivation of Chlorella vulgaris JSC-6 with swine wastewater for simultaneous nutrient/COD removal and carbohydrate production.

PubMed

Wang, Yue; Guo, Wanqian; Yen, Hong-Wei; Ho, Shih-Hsin; Lo, Yung-Chung; Cheng, Chieh-Lun; Ren, Nanqi; Chang, Jo-Shu

2015-12-01

Swine wastewater, containing a high concentration of COD and ammonia nitrogen, is suitable for the growth of microalgae, leading to simultaneous COD/nutrients removal from the wastewater. In this study, an isolated carbohydrate-rich microalga Chlorella vulgaris JSC-6 was adopted to perform swine wastewater treatment. Nearly 60-70% COD removal and 40-90% NH3-N removal was achieved in the mixotrophic and heterotrophic culture, depending on the dilution ratio of the wastewater, while the highest removal percentage was obtained with 20-fold diluted wastewater. Mixotrophic cultivation by using fivefold diluted wastewater resulted in the highest biomass concentration of 3.96 g/L. The carbohydrate content of the microalga grown on the wastewater can reach up to 58% (per dry weight). The results indicated that the microalgae-based wastewater treatment can efficiently reduce the nutrients and COD level, and the resulting microalgal biomass had high carbohydrate content, thereby having potential applications for the fermentative production of biofuels or chemicals. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Effect of pilot UASB-SFSBR-MAP process for the large scale swine wastewater treatment].

PubMed

Wang, Liang; Chen, Chong-Jun; Chen, Ying-Xu; Wu, Wei-Xiang

2013-03-01

In this paper, a treatment process consisted of UASB, step-fed sequencing batch reactor (SFSBR) and magnesium ammonium phosphate precipitation reactor (MAP) was built to treat the large scale swine wastewater, which aimed at overcoming drawbacks of conventional anaerobic-aerobic treatment process and SBR treatment process, such as the low denitrification efficiency, high operating costs and high nutrient losses and so on. Based on the treatment process, a pilot engineering was constructed. It was concluded from the experiment results that the removal efficiency of COD, NH4(+) -N and TP reached 95.1%, 92.7% and 88.8%, the recovery rate of NH4(+) -N and TP by MAP process reached 23.9% and 83.8%, the effluent quality was superior to the discharge standard of pollutants for livestock and poultry breeding (GB 18596-2001), mass concentration of COD, TN, NH4(+) -N, TP and SS were not higher than 135, 116, 43, 7.3 and 50 mg x L(-1) respectively. The process developed was reliable, kept self-balance of carbon source and alkalinity, reached high nutrient recovery efficiency. And the operating cost was equal to that of the traditional anaerobic-aerobic treatment process. So the treatment process could provide a high value of application and dissemination and be fit for the treatment pf the large scale swine wastewater in China.

Coupling biofiltration process and electrocoagulation using magnesium-based anode for the treatment of landfill leachate.

PubMed

Oumar, Dia; Patrick, Drogui; Gerardo, Buelna; Rino, Dubé; Ihsen, Ben Salah

2016-10-01

In this research paper, a combination of biofiltration (BF) and electrocoagulation (EC) processes was used for the treatment of sanitary landfill leachate. Landfill leachate is often characterized by the presence of refractory organic compounds (BOD/COD < 0.13). BF process was used as secondary treatment to remove effectively ammonia nitrogen (N-NH4 removal of 94%), BOD (94% removed), turbidity (95% removed) and phosphorus (more than 98% removed). Subsequently, EC process using magnesium-based anode was used as tertiary treatment. The best performances of COD and color removal from landfill leachate were obtained by applying a current density of 10 mA/cm(2) through 30 min of treatment. The COD removal reached 53%, whereas 85% of color removal was recorded. It has been proved that the alkalinity had a negative effect on COD removal during EC treatment. COD removal efficiencies of 52%, 41% and 27% were recorded in the presence of 1.0, 2.0 and 3.0 g/L of sodium bicarbonate (NaHCO3), respectively. Hydroxide ions produced at the cathode electrode reacted with the bicarbonate ions to form carbonates. The presence of bicarbonates in solution hampered the increase in pH, so that the precipitation of magnesium hydroxides could not take place to effectively remove organic pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of a fine sediment removal tool in spring-fed and snowmelt driven streams

USGS Publications Warehouse

Sepulveda, Adam; Layhee, Megan J.; Sutphin, Zach; Sechrist, Juddson D.

2015-01-01

The accumulation of fine-grained sediments impairs the structure and function of streams, so removing fine sediments may be required to achieve restoration objectives. There has been little work on methods of removing excess sediment or on the efficacy of the methods. We used a 4-year before-after-control-impact design in southeastern Idaho streams to test a fine sediment removal system (FSRS) manufactured by Streamside Environmental LLC. The FSRS agitates fine sediment in the substrate with clean pump water and then vacuums the sediment out of the stream with a second pump. Our objectives were: 1) to test if the FSRS can selectively remove fine sediment; 2) to monitor the bio-physical responses in FSRS treated and downstream waters; and 3) to compare the bio-physical responses to the FSRS in spring-fed and snowmelt driven stream reaches. The FSRS removed ~ 14 metric tons of sediment from the two treated reaches. More than 90% of this sediment was < 2 mm, indicating that the FSRS selected for fine sediment in both stream types. Sustained effects of removing this sediment were confined to substrate improvements in treated reaches. Embeddedness in the spring-fed reach decreased and subsurface grain size in spring-fed and snowmelt driven reaches increased. We did not detect any sustained invertebrate or fish responses in treated reaches or any detrimental bio-physical responses in downstream waters. These results indicate that the FSRS reduced fine sediment levels but sediment removal did not reverse the impacts of sediment accumulation to stream biota within our monitoring time frame.

Coproduction of hydrogen and methane via anaerobic fermentation of cornstalk waste in continuous stirred tank reactor integrated with up-flow anaerobic sludge bed.

PubMed

Cheng, Xi-Yu; Li, Qian; Liu, Chun-Zhao

2012-06-01

A 10 L continuous stirred tank reactor (CSTR) system was developed for a two-stage hydrogen fermentation process with an integrated alkaline treatment. The maximum hydrogen production rate reached 218.5 mL/L h at a cornstalk concentration of 30 g/L, and the total hydrogen yield and volumetric hydrogen production rate reached 58.0 mL/g-cornstalk and 0.55-0.57 L/L d, respectively. A 10 L up-flow anaerobic sludge bed (UASB) was used for continuous methane fermentation of the effluents obtained from the two-stage hydrogen fermentation. At the optimal organic loading rate of 15.0 g-COD/Ld, the COD removal efficiency and volumetric biogas production rate reached 83.3% and 4.6L/Ld, respectively. Total methane yield reached 200.9 mL/g-cornstalk in anaerobic fermentation with the effluents and alkaline hydrolysate. As a result, the total energy recovery by coproduction of hydrogen and methane with anaerobic fermentation of cornstalk reached 67.1%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device.

PubMed

Nguyen, Diem-Mai Kim; Imai, Tsuyoshi; Dang, Thanh-Loc Thi; Kanno, Ariyo; Higuchi, Takaya; Yamamoto, Koichi; Sekine, Masahiko

2018-03-01

This paper presents the results from using a physical absorption process to absorb gaseous CO 2 mixed with N 2 using water by producing tiny bubbles via a liquid-film-forming device (LFFD) that improves the solubility of CO 2 in water. The influence of various parameters-pressure, initial CO 2 concentration, gas-to-liquid ratios, and temperature-on the CO 2 removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method (RSM) with a central composite design (CCD). Based on the analysis, a high efficiency of CO 2 capture can be reached in conditions such as low pressure, high CO 2 concentration at the inlet, low gas/liquid ratio, and low temperature. For instance, the highest removal efficiency in the RSM-CCD experimental matrix of nearly 80% occurred for run number 20, which was conducted at 0.30MPa, CO 2 concentration of 35%, gas/liquid ratio of 0.71, and temperature of 15°C. Furthermore, the coefficients of determination, R 2 , were 0.996 for the removal rate and 0.982 for the absorption rate, implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values. The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO 2 capture in air pollution treatment. Copyright © 2017. Published by Elsevier B.V.

Fate and removal of pharmaceuticals and illicit drugs in conventional and membrane bioreactor wastewater treatment plants and by riverbank filtration.

PubMed

Petrovic, Mira; de Alda, Maria Jose Lopez; Diaz-Cruz, Silvia; Postigo, Cristina; Radjenovic, Jelena; Gros, Meritxell; Barcelo, Damià

2009-10-13

Pharmaceutically active compounds (PhACs) and drugs of abuse (DAs) are two important groups of emerging environmental contaminants that have raised an increasing interest in the scientific community. A number of studies revealed their presence in the environment. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, being able to reach surface and groundwater and subsequently, drinking waters. This paper reviews the data regarding the levels of pharmaceuticals and illicit drugs detected in wastewaters and gives an overview of their removal by conventional treatment technologies (applying activated sludge) as well as advanced treatments such as membrane bioreactor. The paper also gives an overview of bank filtration practices at managed aquifer recharge sites and discusses the potential of this approach to mitigate the contamination by PhACs and DAs.

Peach gum for efficient removal of methylene blue and methyl violet dyes from aqueous solution.

PubMed

Zhou, Li; Huang, Jiachang; He, Benzhao; Zhang, Faai; Li, Huabin

2014-01-30

This study investigated the potential use of natural peach gum (PG) as alternative adsorbent for the removal of dyes from aqueous solutions. The PG showed high adsorption capacities and selectivity for cationic dyes (e.g., methylene blue (MB) and methyl violet (MV)) in the pH range 6-10. 98% of MB and MV could be adsorbed within 5 min, and both of the adsorptions reached equilibrium within 30 min. The dye uptake process followed the pseudo-second-order kinetic model. The intraparticle diffusion was not the sole rate controlling step. Equilibrium adsorption isotherm data indicated a good fit to the Langmuir isotherm model. Regeneration study revealed that PG could be well regenerated in acid solution. The recovered PG still exhibited high adsorption capacity even after five cycles of desorption-adsorption. On the basis of its excellent adsorption performance and facile availability, PG can be employed as an efficient low cost adsorbent for environmental cleanup. Copyright © 2013 Elsevier Ltd. All rights reserved.

Facile Fabrication of Nanofibrillated Chitin/Ag2O Heterostructured Aerogels with High Iodine Capture Efficiency.

PubMed

Gao, Runan; Lu, Yun; Xiao, Shaoliang; Li, Jian

2017-06-27

Nanofibrillated chitin/Ag 2 O aerogels were fabricated for radioiodine removal. Chitin was first fabricated into nanofibers with abundant acetyl amino groups (-NHCOCH 3 ) on the surface. Then, highly porous chitin nanofiber (ChNF) aerogels were obtained via freeze-drying. The ChNF aerogels exhibited a low bulk density of 2.19 mg/cm 3 and a high specific surface area of 179.71 m 2 /g. Ag 2 O nanoparticles were evenly anchored on the surfaces of ChNF scaffolds via strong interactions with -NHCOCH 3 groups, subsequently yielding Ag 2 O@ChNF heterostructured aerogels. The composites were used as efficient absorbents to remove radioiodine anions from water and capture a high amount of I 2 vapor in the forms of AgI and iodine molecules. The adsorption capacity of the composite monoliths can reach up to 2.81 mmol/g of I - anions. The high adsorbability of the composite monolithic aerogel signifies its potential applications in radioactive waste disposal.

Preparation, characterization, and testing of metal-doped carbon xerogels as catalyst for phenol CWAO.

PubMed

Pleşa Chicinaş, Raluca; Coteţ, L Cosmin; Măicăneanu, Andrada; Vasilescu, Mihai; Vulpoi, Adriana

2017-01-01

Co-, Ce-, and Ni-doped carbon xerogels (Me-CX) synthesized by sol-gel method followed by an ion exchange process were used as catalysts for catalytic wet air oxidation (CWAO) of phenol. The prepared catalysts were characterized using TEM, SEM, BET surface area, and XRD. Me-CX catalysts were tested in mild conditions (20-60 °C, atmospheric pressure) in a semi-batch reactor in various reaction conditions (30-60 L/h, 0.05-0.2 g catalysts, 50-175 mg phenol/L). Total organic carbon (TOC) removal efficiency values obtained decrease in the following order Co-CX ≅ Ce-CX > Ni1-CX > K-CX for the catalysts obtained using the same procedure. TOC removal efficiencies of up to 72% were reached in case of Co-CX catalyst at 20 °C, 40 L/h, using 0.15 g catalyst and a solution of 100 mg phenol/L.

Study on anaerobic treatment of wastewater containing hexavalent chromium*

PubMed Central

Xu, Yan-bin; Xiao, Hua-hua; Sun, Shui-yu

2005-01-01

A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and CODCr of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr6+ removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms. PMID:15909347

Integrated campus sewage treatment and biomass production by Scenedesmus quadricauda SDEC-13.

PubMed

Han, Lin; Pei, Haiyan; Hu, Wenrong; Jiang, Liqun; Ma, Guixia; Zhang, Shuo; Han, Fei

2015-01-01

The notion of wastewater treatment combined with biomass production is potential and prospective. Campus sewage was utilized twice in procession to cultivate the newly isolated microalgae Scenedesmus quadricauda SDEC-13. Nutrients was efficiently removed with the phosphorus and nitrogen removal efficiency nearly 100% and more than 70% respectively in twice use of campus sewage. Ammonium was consumed rapidly within five days in 1st use. There was no significant difference in the lipid and protein content but distinct difference in their respective productivity which is ascribed to the lower biomass productivity caused by limited nutrients in 2nd use. The diverse nutrient concentration in twice use of campus sewage and BG-11 had effects on the composition of fatty acids and amino acids. SDEC-13 performed better biodiesel quality compared with BG-11 medium and produced high quality protein when cultivated in campus sewage. Finally, the campus sewage after twice use reached the corresponding discharge standard. Copyright © 2014 Elsevier Ltd. All rights reserved.

PCDD/F adsorption and destruction in the flue gas streams of MWI and MSP via Cu and Fe catalysts supported on carbon.

PubMed

Chang, Shu Hao; Yeh, Jhy Wei; Chein, Hung Min; Hsu, Li Yeh; Chi, Kai Hsien; Chang, Moo Been

2008-08-01

Catalytic destruction has been applied to control polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) emissions from different facilities. The cost of carbon-based catalysts is considerably lower than that of the metal oxide or zeolite-based catalysts used in the selective catalytic reduction (SCR) system. In this study, destruction and adsorption efficiencies of PCDD/Fs achieved with Cu/C and Fe/C catalysts from flue gas streams of a metal smelting plant (MSP) and a large-scale municipal waste incinerator (MWI), respectively, are evaluated via the pilot-scale catalytic reactor system (PCRS). The results indicate that Cu and Fe catalysts supported on carbon surface are capable of decomposing and adsorbing PCDD/ Fs from gas streams. In the testing sources of MSP and MWI, the PCDD/F removal efficiencies achieved with Cu/C catalyst at 250 degrees C reach 96%, however, the destruction efficiencies are negative (-1,390% and -112%, respectively) due to significant PCDD/F formation on catalyst promoted by copper. In addition, Fe/C catalyst is of higher removal and destruction efficiencies compared with Cu/C catalyst in both testing sources. The removal efficiencies of PCDD/Fs achieved with Fe/C catalyst are 97 and 94% for MSP and MWI, respectively, whereas the destruction efficiencies are both higher than 70%. Decrease of PCDD/F destruction efficiency and increase of adsorption efficiency with increasing chlorination of dioxin congeners is also observed in the test via three-layer Fe/C catalyst. Furthermore, the mass of 2,3,7,8-PCDD/Fs retained on catalyst decreases on the order of first to third layer of catalyst. Each gram Fe/C catalyst in first layer adsorbs 10.9, 6.91, and 3.04 ng 2,3,7,8-PCDD/Fs in 100 min testing duration as the operating temperature is controlled at 150, 200, and 250 degrees C, respectively.

[Treatment effect of biological filtration and vegetable floating-bed combined system on greenhouse turtle breeding wastewater].

PubMed

Chen, Chong-Jun; Zhang, Rui; Xiang, Kun; Wu, Wei-Xiang

2014-08-01

Unorganized discharge of greenhouse turtle breeding wastewater has brought several negative influences on the ecological environment in the rural area of Yangtze River Delta. Biological filtration and vegetable floating-bed combined system is a potential ecological method for greenhouse turtle breeding wastewater treatment. In order to explore the feasibility of this system and evaluate the contribution of vegetable uptake of nitrogen (N) and phosphorus (P) in treating greenhouse turtle breeding wastewater, three types of vegetables, including Ipomoea aquatica, lettuce and celery were selected in this study. Results showed the combined system had a high capacity in simultaneous removal of organic matter, N and P. The removal efficiencies of COD, NH4(+)-N, TN and TP from the wastewater reached up to 93.2%-95.6%, 97.2%-99.6%, 73.9%-93.1% and 74.9%-90.0%, respectively. System with I. aquatica had the highest efficiencies in N and P removal, followed by lettuce and celery. However, plant uptake was not the primary pathway for TN arid TP removal in the combined system. The vegetable uptake of N and P accounted for only 9.1%-25.0% of TN and TP removal from the wastewater while the effect of microorganisms would be dominant for N and P removal. In addition, the highest amounts of N and P uptake in I. aquatica were closely related with the biomass of plant. Results from the study indicated that the biological filtration and vegetable floating-bed combined system was an effective approach to treating greenhouse turtle breeding wastewater in China.

High Efficient Visible-Light Photocatalytic Performance of Cu/ZnO/rGO Nanocomposite for Decomposing of Aqueous Ammonia and Treatment of Domestic Wastewater.

PubMed

He, Shiying; Hou, Pengfu; Petropoulos, Evangelos; Feng, Yanfang; Yu, Yingliang; Xue, Lihong; Yang, Linzhang

2018-01-01

Photocatalytic removal of ammonium-nitrogen ( NH 4 + -N) from water using solar energy is an approach of high interest and applicability due to the convenience in application. ZnO has a great potential in photocatalytic decomposition of NH 4 + -N and conversion of this nutrient to under visible light irradiations. However the applicability of pristine ZnO though is limited due to its reduced capacity to utilize light from natural light. Herein, we report a two-step ZnO-modified strategy (Cu-doped ZnO nanoparticles, immobilized on reduced graphene oxide (rGO) sheets) for the promotion of photocatalytic degradation of NH 4 + -N under visible light. UV-Vis spectra showed that the Cu/ZnO/rGO can be highly efficient in the utilization of photons from the visible region. Hence, Cu/ZnO/rGO managed to demonstrate adequate photocatalytic activity and effective NH 4 + -N removal from water under visible light compared to single ZnO. Specifically, up to 83.1% of NH 4 + -N (initial concentration 50 mg·L -1 , catalyst dosage 2 g·L -1 , pH 10) was removed within 2 h retention time under Xe lamp irradiation. From the catalysis, the major by-product was N 2 . The high ammonia degradation efficiency from the ZnO/Cu/rGO is attributed to the improvement of the reactive oxygen species (ROSs) production efficiency and the further activation of the interfacial catalytic sites. This study also demonstrated that such nanocomposite is a recyclable agent. Its NH 4 + -N removal capacity remained effective even after five batch cycles. In addition, Cu/ZnO/rGO was applied to treat real domestic wastewater, and it was found that chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies can reach 84.3, 80.7, and 90.3%, respectively. Thus, Cu/ZnO/rGO in the presence of solar light can be a promising photocatalyst in the field of wastewater treatment.

Recycling of aluminium scrap for secondary Al-Si alloys.

PubMed

Velasco, Eulogio; Nino, Jose

2011-07-01

An increasing amount of recycled aluminium is going into the production of aluminium alloy used for automotive applications. In these applications, it is necessary to control and remove alloy impurities and inclusions. Cleaning and fluxing processes are widely used during processing of the alloys for removal of inclusions, hydrogen and excess of magnesium. These processes use salt fluxes based in the system NaCl-KCl, injection of chlorine or mixture of chlorine with an inert gas. The new systems include a graphite wand and a circulation device to force convection in the melt and permit the bubbling and dispersion of reactive and cleaning agents. This paper discusses the recycling of aluminium alloys in rotary and reverberatory industrial furnaces. It focuses on the removal of magnesium during the melting process. In rotary furnaces, the magnesium lost is mainly due to the oxidation process at high temperatures. The magnesium removal is carried out by the reaction between chlorine and magnesium, with its efficiency associated to kinetic factors such as concentration of magnesium, mixing, and temperature. These factors are also related to emissions generated during the demagging process. Improvements in the metallic yield can be reached in rotary furnaces if the process starts with a proper salt, with limits of addition, and avoiding long holding times. To improve throughput in reverberatories, start the charging with high magnesium content material and inject chlorine gas if the molten metal is at the right temperature. Removal of magnesium through modern technologies can be efficiently performed to prevent environmental problems.

Decolorization of basic dye solutions by electrocoagulation: an investigation of the effect of operational parameters.

PubMed

Daneshvar, N; Oladegaragoze, A; Djafarzadeh, N

2006-02-28

Electrocoagulation (EC) is one of the most effective techniques to remove color and organic pollutants from wastewater, which reduces the sludge generation. In this paper, electrocoagulation has been used for the removal of color from solutions containing C. I. Basic Red 46 (BR46) and C. I. Basic Blue 3 (BB3). These dyes are used in the wool and blanket factories for fiber dyeing. The effect of operational parameters such as current density, initial pH of the solution, time of electrolysis, initial dye concentration and solution conductivity were studied in an attempt to reach higher removal efficiency. The findings in this study shows that an increase in the current density up to 60-80 A m(-2) enhanced the color removal efficiency, the electrolysis time was 5 min and the range of pH was determined between 5.5 and 8.5 for two mentioned dye solutions. It was found that for, the initial concentration of dye in solutions should not be higher than 80 mg l(-1) in order to achieve a high color removal percentage. The optimum conductivity was found to be 8 mS cm(-1), which was adjusted using proper amount of NaCl with the dye concentration of 50 mg l(-1). Electrical energy consumption in the above conditions for the decolorization of the dye solutions containing BR46 and BB3 were 4.70 kWh(kgdye removed)(-1) and 7.57 kWh(kgdye removed)(-1), respectively. Also, during the EC process under the optimized conditions, the COD decreased by more than 75% and 99% in dye solutions containing BB3 and BR46, respectively.

Hydrodynamic behaviour and comparison of technologies for the removal of excess biomass in gas-phase biofilters.

PubMed

Mendoza, J A; Prado, O J; Veiga, M C; Kennes, C

2004-01-01

The hydrodynamic behaviour of a biofilter fed toluene and packed with an inert carrier was evaluated on start-up and after long-term operation, using both methane and styrene as tracers in Residence Time Distribution experiments. Results indicated some deviation from ideal plug flow behaviour after 2-year operation. It was also observed that the retention time of VOCs gradually increased with time and was significantly longer than the average residence time of the bulk gas phase. Non-ideal hydrodynamic behaviour in packed beds may be due to excess biomass accumulation and affects both reactor modeling and performance. Therefore, several methods were studied for the removal of biomass after long-term biofilter operation: filling with water and draining, backwashing, and air sparging. Several flow rates and temperatures (20-60 degrees C) were applied using either water or different chemicals (NaOH, NaOCl, HTAB) in aqueous solution. Usually, higher flow rates and higher temperatures allowed the removal of more biomass, but the efficiency of biomass removal was highly dependent on the pressure drop reached before the treatment. The filling/draining method was the least efficient for biomass removal, although the treatment did basically not generate any biological inhibition. The efficiency of backwashing and air sparging was relatively similar and was more effective when adding chemicals. However, treatments with chemicals resulted in a significant decrease of the biofilter's performance immediately after applying the treatment, needing periods of several days to recover the original performance. The effect of manually mixing the packing material was also evaluated in duplicate experiments. Quite large amounts of biomass were removed but disruption of the filter bed was observed. Batch assays were performed simultaneously in order to support and quantify the observed inhibitory effects of the different chemicals and temperatures used during the treatments.

Biosorption of Mercury (II) from Aqueous Solutions onto Fungal Biomass

PubMed Central

Martínez-Juárez, Víctor M.; Cárdenas-González, Juan F.; Torre-Bouscoulet, María Eugenia; Acosta-Rodríguez, Ismael

2012-01-01

The biosorption of mercury (II) on 14 fungal biomasses, Aspergillus flavus I–V, Aspergillus fumigatus I-II, Helminthosporium sp., Cladosporium sp., Mucor rouxii mutant, M. rouxii IM-80, Mucor sp 1 and 2, and Candida albicans, was studied in this work. It was found that the biomasses of the fungus M. rouxii IM-80, M. rouxii mutant, Mucor sp1, and Mucor sp 2 were very efficient removing the metal in solution, using dithizone, reaching the next percentage of removals: 95.3%, 88.7%, 80.4%, and 78.3%, respectively. The highest adsorption was obtained at pH 5.5, at 30°C after 24 hours of incubation, with 1 g/100 mL of fungal biomass. PMID:23028382

Analysis of economic and environmental benefits of a new heat pump air conditioning system with a heat recovery device

NASA Astrophysics Data System (ADS)

Li, lingxue

2017-08-01

The paper designs a new wind-water cooling and heating water conditioner system, connects cooling tower with heat recovery device, which uses cooling water to completely remove the heat that does not need heat recollection, in order to ensure that the system can work efficiently with higher performance coefficient. After the test actual engineering operation, the system’s maximum cooling coefficient of performance can reach 3.5. Its maximum comprehensive coefficient of performance can reach 6.5. After the analysis of its economic and environmental, we conclude that the new system can save 89822 kw per year. It reflects energy-saving and environmental benefits of the cold and hot water air conditioning system.

The use of oak chips and coconut fiber as biofilter media to remove vocs in rendering process.

PubMed

Tymczyna, Leszek; Chmielowiec-Korzeniowska, Anna; Paluszak, Zbigniew; Dobrowolska, Magadalena; Banach, Marcin; Pulit, Jolanta

2013-01-01

The study evaluated the effectiveness of air biofiltration in rendering plants. The biofilter material comprised compost soil (40%) and peat (40%) mixed up with coconut fiber (medium A) and oak bark (medium B). During biofiltration average VOCs reduction reached 88.4% for medium A and 89.7% for medium B. A positive relationship of aldehyde reduction from material humidity (r = 0.502; α<0.05) was also noted. Other biomaterial parameters did not affect the treatment efficiency.

Characterization and limits of a cold-atom Sagnac interferometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gauguet, A.; Canuel, B.; Leveque, T.

2009-12-15

We present the full evaluation of a cold-atom gyroscope based on atom interferometry. We have performed extensive studies to determine the systematic errors, scale factor and sensitivity. We demonstrate that the acceleration noise can be efficiently removed from the rotation signal, allowing us to reach the fundamental limit of the quantum projection noise for short term measurements. The technical limits to the long term sensitivity and accuracy have been identified, clearing the way for the next generation of ultrasensitive atom gyroscopes.

Bioremediation of a weathered and a recently oil-contaminated soils from Brazil: a comparison study.

PubMed

Trindade, P V O; Sobral, L G; Rizzo, A C L; Leite, S G F; Soriano, A U

2005-01-01

The facility with which hydrocarbons can be removed from soils varies inversely with aging of soil samples as a result of weathering. Weathering refers to the result of biological, chemical and physical processes that can affect the type of hydrocarbons that remain in a soil. These processes enhance the sorption of hydrophobic organic contaminants (HOCs) to the soil matrix, decreasing the rate and extent of biodegradation. Additionally, pollutant compounds in high concentrations can more easily affect the microbial population of a recently contaminated soil than in a weathered one, leading to inhibition of the biodegradation process. The present work aimed at comparing the biodegradation efficiencies obtained in a recently oil-contaminated soil (spiked one) from Brazil and an weathered one, contaminated for four years, after the application of bioaugmentation and biostimulation techniques. Both soils were contaminated with 5.4% of total petroleum hydrocarbons (TPHs) and the highest biodegradation efficiency (7.4%) was reached for the weathered contaminated soil. It could be concluded that the low biodegradation efficiencies reached for all conditions tested reflect the treatment difficulty of a weathered soil contaminated with a high crude oil concentration. Moreover, both soils (weathered and recently contaminated) submitted to bioaugmentation and biostimulation techniques presented biodegradation efficiencies approximately twice as higher as the ones without the aforementioned treatment (natural attenuation).

Preparation of low cost activated carbon from Myrtus communis and pomegranate and their efficient application for removal of Congo red from aqueous solution

NASA Astrophysics Data System (ADS)

Ghaedi, Mehrorang; Tavallali, Hossein; Sharifi, Mahdi; Kokhdan, Syamak Nasiri; Asghari, Alireza

2012-02-01

In this research, the potential applicability of activated carbon prepared from Myrtus communis (AC-MC) and pomegranate (AC-PG) as useful adsorbents for the removal of Congo red (CR) from aqueous solutions in batch method was investigated. The effects of pH, contact time, agitation time and amount of adsorbents on removal percentage of Congo red on both adsorbents were examined. Increase in pH up to 6 for AC-MC and pH 7 for AC-PG increase the adsorption percentage (capacity) and reach equilibrium within 30 min of contact time. Fitting the experimental data to conventional isotherm models like Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich show that the experimental data fitted very well to the Freundlich isotherm for AC-MC and Langmuir isotherm for AC-PG. Fitting the experimental data to different kinetic models such as pseudo first-order, pseudo second-order, Elovich and intraparticle diffusion mechanism showed the applicability of a pseudo second-order with involvement of intraparticle diffusion model for interpretation of experimental data for both adsorbents. The adsorption capacity of AC-PG and AC-MC for the removal of CR was found to be 19.231 and 10 mg g -1. These results clearly indicate the efficiency of adsorbents as a low cost adsorbent for treatment of wastewater containing CR.

Preparation of low cost activated carbon from Myrtus communis and pomegranate and their efficient application for removal of Congo red from aqueous solution.

PubMed

Ghaedi, Mehrorang; Tavallali, Hossein; Sharifi, Mahdi; Kokhdan, Syamak Nasiri; Asghari, Alireza

2012-02-01

In this research, the potential applicability of activated carbon prepared from Myrtus communis (AC-MC) and pomegranate (AC-PG) as useful adsorbents for the removal of Congo red (CR) from aqueous solutions in batch method was investigated. The effects of pH, contact time, agitation time and amount of adsorbents on removal percentage of Congo red on both adsorbents were examined. Increase in pH up to 6 for AC-MC and pH 7 for AC-PG increase the adsorption percentage (capacity) and reach equilibrium within 30 min of contact time. Fitting the experimental data to conventional isotherm models like Freundlich, Langmuir, Tempkin and Dubinin-Radushkevich show that the experimental data fitted very well to the Freundlich isotherm for AC-MC and Langmuir isotherm for AC-PG. Fitting the experimental data to different kinetic models such as pseudo first-order, pseudo second-order, Elovich and intraparticle diffusion mechanism showed the applicability of a pseudo second-order with involvement of intraparticle diffusion model for interpretation of experimental data for both adsorbents. The adsorption capacity of AC-PG and AC-MC for the removal of CR was found to be 19.231 and 10 mg g(-1). These results clearly indicate the efficiency of adsorbents as a low cost adsorbent for treatment of wastewater containing CR. Copyright © 2011 Elsevier B.V. All rights reserved.

Performance of dithiocarbamate-type flocculant in treating simulated polymer flooding produced water.

PubMed

Gao, Baoyu; Jia, Yuyan; Zhang, Yongqiang; Li, Qian; Yue, Qinyan

2011-01-01

Produced water from polymer flooding is difficult to treat due to its high polymer concentration, high viscosity, and emulsified characteristics. The dithiocarbamate flocculant, DTC (T403), was prepared by the amine-terminated polyoxypropane-ether compound known as Jeffamine-T403. The product was characterized by IR spectra and elemental analysis. The DTC agent chelating with Fe2+ produced a network polymer matrix, which captured and removed oil droplets efficiently. Oil removal by the flocculent on simulated produced water with 0, 200, 500, 900 mg/L of partially hydrolyzed polyacrylamide (HPAM) was investigated for aspects of effectiveness of DTC (T403) dosage and concentrations of HPAM and Fe2+ ions in the wastewater. Results showed that HPAM had a negative influence on oil removal efficiency when DTC (T403) dosage was lower than 20 mg/L. However, residual oil concentrations in tested samples with different concentrations of HPAM all decreased below 10 mg/L when DTC (T403) dosage reached 30 mg/L. The concentration of Fe2+ in the initial wastewater had a slight effect on oil removal at the range of 2-12 mg/L. Results showed that Fe3+ could not be used in place of Fe2+ as Fe3+ could not react with DTC under flocculated conditions. The effects of mineral salts ions were also investigated.

Efficient Sorption and Removal of Perfluoroalkyl Acids (PFAAs) from Aqueous Solution by Metal Hydroxides Generated in Situ by Electrocoagulation.

PubMed

Lin, Hui; Wang, Yujuan; Niu, Junfeng; Yue, Zhihan; Huang, Qingguo

2015-09-01

Removal of environmentally persistent perfluoroalkyl acids (PFAAs), that is, perfluorooctanesulfonate (PFOS) and perfluorocarboxylic acids (PFCAs, C4 ∼ C10) were investigated through sorption on four metal hydroxide flocs generated in situ by electrocoagulation in deionized water with 10 mM NaCl as supporting electrolyte. The results indicated that the zinc hydroxide flocs yielded the highest removal efficiency with a wide range concentration of PFOA/PFOS (1.5 μM ∼ 0.5 mM) at the zinc dosage <150 mg L(-1) with the energy consumption <0.18 Wh L(-1). The sorption kinetics indicated that the zinc hydroxide flocs had an equilibrium adsorbed amount (qe) up to 5.74/7.69 mmol g(-1) (Zn) for PFOA/PFOS at the initial concentration of 0.5 mM with an initial sorption rate (v0) of 1.01 × 10(3)/1.81 × 10(3) mmol g(-1) h(-1). The sorption of PFOA/PFOS reached equilibrium within <10 min. The sorption mechanisms of PFAAs on the zinc hydroxide flocs were proposed based on the investigation of various driving forces. The results indicated that the hydrophobic interaction was primarily responsible for the PFAAs sorption. The electrocoagulation process with zinc anode may have a great potential for removing PFAAs from industrial wastewater as well as contaminated environmental waterbody.

Novel Process of Simultaneous Removal of Nitric Oxide and Sulfur Dioxide Using a Vacuum Ultraviolet (VUV)-Activated O2/H2O/H2O2 System in A Wet VUV-Spraying Reactor.

PubMed

Liu, Yangxian; Wang, Qian; Pan, Jianfeng

2016-12-06

A novel process for NO and SO 2 simultaneous removal using a vacuum ultraviolet (VUV, with 185 nm wavelength)-activated O 2 /H 2 O/H 2 O 2 system in a wet VUV-spraying reactor was developed. The influence of different process variables on NO and SO 2 removal was evaluated. Active species (O 3 and ·OH) and liquid products (SO 3 2- , NO 2 - , SO 4 2- , and NO 3 - ) were analyzed. The chemistry and routes of NO and SO 2 removal were investigated. The oxidation removal system exhibits excellent simultaneous removal capacity for NO and SO 2 , and a maximum removal of 96.8% for NO and complete SO 2 removal were obtained under optimized conditions. SO 2 reaches 100% removal efficiency under most of test conditions. NO removal is obviously affected by several process variables. Increasing VUV power, H 2 O 2 concentration, solution pH, liquid-to-gas ratio, and O 2 concentration greatly enhances NO removal. Increasing NO and SO 2 concentration obviously reduces NO removal. Temperature has a dual impact on NO removal, which has an optimal temperature of 318 K. Sulfuric acid and nitric acid are the main removal products of NO and SO 2 . NO removals by oxidation of O 3 , O·, and ·OH are the primary routes. NO removals by H 2 O 2 oxidation and VUV photolysis are the complementary routes. A potential scaled-up removal process was also proposed initially.

Nb2O5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(VI).

PubMed

Du, Yucheng; Zhang, Shihao; Wang, Jinshu; Wu, Junshu; Dai, Hongxing

2018-04-01

Niobium oxide nanowire-deposited carbon fiber (CF) samples were prepared using a hydrothermal method with amorphous Nb 2 O 5 ·nH 2 O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV-visible spectroscopy (UV-vis), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr(VI) was determined. Parameters such as pH value and initial Cr(VI) concentration could influence the Cr(VI) removal efficiency or adsorption capacity of the Nb 2 O 5 /carbon fiber sample obtained after hydrothermal treatment at 160°C for 14hr. The maximal Cr(VI) adsorption capacity of the Nb 2 O 5 nanowire/CF sample was 115mg/g. This Nb 2 O 5 /CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr(VI) under UV-light irradiation: the Cr(VI) removal efficiency reached 99.9% after UV-light irradiation for 1hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr(VI) adsorption capacity and photocatalytic performance was related to its high surface area, abundant surface hydroxyl groups, and good UV-light absorption ability. Copyright © 2017. Published by Elsevier B.V.

Microalgal biomass production and on-site bioremediation of carbon dioxide, nitrogen oxide and sulfur dioxide from flue gas using Chlorella sp. cultures.

PubMed

Chiu, Sheng-Yi; Kao, Chien-Ya; Huang, Tzu-Ting; Lin, Chia-Jung; Ong, Seow-Chin; Chen, Chun-Da; Chang, Jo-Shu; Lin, Chih-Sheng

2011-10-01

The growth and on-site bioremediation potential of an isolated thermal- and CO₂-tolerant mutant strain, Chlorella sp. MTF-7, were investigated. The Chlorella sp. MTF-7 cultures were directly aerated with the flue gas generated from coke oven of a steel plant. The biomass concentration, growth rate and lipid content of Chlorella sp. MTF-7 cultured in an outdoor 50-L photobioreactor for 6 days was 2.87 g L⁻¹ (with an initial culture biomass concentration of 0.75 g L⁻¹), 0.52 g L⁻¹ d⁻¹ and 25.2%, respectively. By the operation with intermittent flue gas aeration in a double-set photobioreactor system, average efficiency of CO₂ removal from the flue gas could reach to 60%, and NO and SO₂ removal efficiency was maintained at approximately 70% and 50%, respectively. Our results demonstrate that flue gas from coke oven could be directly introduced into Chlorella sp. MTF-7 cultures to potentially produce algal biomass and efficiently capture CO₂, NO and SO₂ from flue gas. Copyright © 2011 Elsevier Ltd. All rights reserved.

Environmental effects of the Big Rapids dam remnant removal, Big Rapids, Michigan, 2000-02

USGS Publications Warehouse

Healy, Denis F.; Rheaume, Stephen J.; Simpson, J. Alan

2003-01-01

The U.S. Geological Survey (USGS), in cooperation with the city of Big Rapids, investigated the environmental effects of removal of a dam-foundation remnant and downstream cofferdam from the Muskegon River in Big Rapids, Mich. The USGS applied a multidiscipline approach, which determined the water quality, sediment character, and stream habitat before and after dam removal. Continuous water-quality data and discrete water-quality samples were collected, the movement of suspended and bed sediment were measured, changes in stream habitat were assessed, and streambed elevations were surveyed. Analyses of water upstream and downstream from the dam showed that the dam-foundation remnant did not affect water quality. Dissolved-oxygen concentrations downstream from the dam remnant were depressed for a short period (days) during the beginning of the dam removal, in part because of that removal effort. Sediment transport from July 2000 through March 2002 was 13,800 cubic yards more at the downstream site than the upstream site. This increase in sediment represents the remobilized sediment upstream from the dam, bank erosion when the impoundment was lowered, and contributions from small tributaries between the sites. Five habitat reaches were monitored before and after dam-remnant removal. The reaches consisted of a reference reach (A), upstream from the effects of the impoundment; the impoundment (B); and three sites below the impoundment where habitat changes were expected (C, D, and E, in downstream order). Stream-habitat assessment reaches varied in their responses to the dam-remnant removal. Reference reach A was not affected. In impoundment reach B, Great Lakes and Environmental Assessment Section (GLEAS) Procedure 51 ratings went from fair to excellent. For the three downstream reaches, reach C underwent slight habitat degradation, but ratings remained good; reach D underwent slight habitat degradation with ratings changing from excellent to good; and, in an area affected by a 1966 sediment release, reach E habitat rated fair in April 2000 and remained fair in September 2001. The most noticeable habitat change in the three reaches downstream from the dam site was a measurable increase in siltation and embeddedness. Bed-elevation profiles show that bed material upstream from the dam site was remobilized as suspended sediment and bedload, and was redeposited in the reaches below the cofferdam. Deposition was greater in the deep, slow-moving pools than the shallow, fast-moving riffles. For the most part, where deposition took place, deposits were less than 1 foot in thickness. In the year following the removal of the cofferdam, much of the sediment deposited below the dam was moved out of the study reach.

Investigation of lab-scale horizontal subsurface flow constructed wetlands treating industrial cork boiling wastewater.

PubMed

Gomes, Arlindo C; Silva, Lúcia; Albuquerque, António; Simões, Rogério; Stefanakis, Alexandros I

2018-09-01

The feasibility and treatment efficiency of horizontal subsurface flow constructed wetlands (HSFCW) was assessed for the first time for cork boiling wastewater (CBW) through laboratory experiments. CBW is known for its high content of phenolic compounds, complex composition of biorecalcitrant and toxic nature. Two lab-scale units, one planted with Phragmites australis (CWP) and one unplanted (CWC), were used to evaluate the removals of COD, BOD, total phenolic compounds (TPh) and decolourization over a 2.5-years monitoring period under Mediterranean climatic conditions. Seven organic and hydraulic loading rates ranging from 2.6 to 11.5 g COD/m 2 /d and 5.7-9.1 L/m 2 /d were tested under average hydraulic retention time (HRT) of 5 ± 1 days required due to the CWB limited biodegradability (i.e., BOD 5 /COD of 0.19). Average removals of the CWP exceeded those of the CWC and reached 74.6%, 91.7% and 69.1% for COD, BOD 5 and TPh, respectively, with respective mass removals rates up to 7.0, 1.7 and 0.5 (in g/m 2 /d). Decolourization was limited to 35%, since it mainly depends on physical processes rather than biodegradation. CBW concentration of nine phenolic compounds ranged from 1.2 to 38.4 mg/L (for the syringic and ellagic acids, respectively) in the raw CBW, with respective removals in the CWP unit ranging from 41.8 to 76.3%, higher than those in the control unit. Despite CBW high concentration of TPhs (average of 116.3 mg/L), the HSFCW reached organic load removals higher than those of conventional biological treatment methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Surgical Borescopes Remove Contaminants

NASA Technical Reports Server (NTRS)

Vallow, K.

1987-01-01

Borescope instruments put to use in extracting hard-to-reach particles. Surgical instruments in flexible borescopes used for removing contaminant particles from normally inaccessible places within equipment. Instruments readily enter small openings, turn corners, and reach far.

High-rate activated sludge system for carbon management--Evaluation of crucial process mechanisms and design parameters.

PubMed

Jimenez, Jose; Miller, Mark; Bott, Charles; Murthy, Sudhir; De Clippeleir, Haydee; Wett, Bernhard

2015-12-15

The high-rate activated sludge (HRAS) process is a technology suitable for the removal and redirection of organics from wastewater to energy generating processes in an efficient manner. A HRAS pilot plant was operated under controlled conditions resulting in concentrating the influent particulate, colloidal, and soluble COD to a waste solids stream with minimal energy input by maximizing sludge production, bacterial storage, and bioflocculation. The impact of important process parameters such as solids retention time (SRT), hydraulic residence time (HRT) and dissolved oxygen (DO) levels on the performance of a HRAS system was demonstrated in a pilot study. The results showed that maximum removal efficiencies of soluble COD were reached at a DO > 0.3 mg O2/L, SRT > 0.5 days and HRT > 15 min which indicates that minimizing the oxidation of the soluble COD in the high-rate activated sludge process is difficult. The study of DO, SRT and HRT exhibited high degree of impact on the colloidal and particulate COD removal. Thus, more attention should be focused on controlling the removal of these COD fractions. Colloidal COD removal plateaued at a DO > 0.7 mg O2/L, SRT > 1.5 days and HRT > 30 min, similar to particulate COD removal. Concurrent increase in extracellular polymers (EPS) production in the reactor and the association of particulate and colloidal material into sludge flocs (bioflocculation) indicated carbon capture by biomass. The SRT impacted the overall mass and energy balance of the high-rate process indicating that at low SRT conditions, lower COD mineralization or loss of COD content occurred. In addition, the lower SRT conditions resulted in higher sludge yields and higher COD content in the WAS. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of the acid treatment conditions of kaolinite on etheramine adsorption: A comparative analysis using chemometric tools.

PubMed

Leal, Paulo Vitor Brandão; Magriotis, Zuy Maria; Sales, Priscila Ferreira de; Papini, Rísia Magriotis; Viana, Paulo Roberto de Magalhães

2017-07-15

The present work evaluated the effect of the acid treatment conditions of natural kaolinite (NK) regarding its efficiency in removing etheramine. The treatment was conducted using sulfuric acid at the concentrations of 1 mol L -1 (KA-01), 2 mol L -1 (KA-02) and 5 mol L -1 (KA-05) at 85 °C. The obtained adsorbents were characterized by X-ray fluorescence, X-ray diffraction, N 2 adsorption/desorption isotherms, zeta potential analysis and infrared spectroscopy. The Response Surface Method was used to optimize adsorption parameters (initial concentration of etheramine, adsorbent mass and pH of the solution). The results, described by means of a central composite design, were adjusted to the quadratic model. Results revealed that the adsorption was more efficient at the etheramine concentration of 400 mg L -1 , pH 10 and adsorbent mass of 0.1 g for NK and 0.2 g for KA-01, KA-02 and KA-05. The sample KA-02 presented a significant increase of etheramine removal compared to the NK sample. The adsorption kinetics conducted under optimized conditions showed that the system reached the equilibrium in approximately 30 min. The kinetic data were better adjusted to the pseudo-second order model. The isotherm data revealed that the Sips model was the most adequate one. The calculation of E ads allowed to infer that the mechanism for etheramine removal in all the evaluated samples was chemisorption. The reuse tests showed that, after four uses, the efficiency of adsorbents in removing etheramine did not suffer significant modifications, which makes the use of kaolinite to treat effluents from the reverse flotation of iron ore feasible. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient treatment of azo dye containing wastewater in a hybrid acidogenic bioreactor stimulated by biocatalyzed electrolysis.

PubMed

Wang, Hong-Cheng; Cheng, Hao-Yi; Wang, Shu-Sen; Cui, Dan; Han, Jing-Long; Hu, Ya-Ping; Su, Shi-Gang; Wang, Ai-Jie

2016-01-01

In this study, a novel scaled-up hybrid acidogenic bioreactor (HAB) was designed and adopted to evaluate the performance of azo dye (acid red G, ARG) containing wastewater treatment. Principally, HAB is an acidogenic bioreactor coupled with a biocatalyzed electrolysis module. The effects of hydraulic retention time (HRT) and ARG loading rate on the performance of HAB were investigated. In addition, the influent was switched from synthetic wastewater to domestic wastewater to examine the key parameters for the application of HAB. The results showed that the introduction of the biocatalyzed electrolysis module could enhance anoxic decolorization and COD (chemical oxygen demand) removal. The combined process of HAB-CASS presented superior performance compared to a control system without biocatalyzed electrolysis (AB-CASS). When the influent was switched to domestic wastewater, with an environment having more balanced nutrients and diverse organic matters, the ARG, COD and nitrogen removal efficiencies of HAB-CASS were further improved, reaching 73.3%±2.5%, 86.2%±3.8% and 93.5%±1.6% at HRT of 6 hr, respectively, which were much higher than those of AB-CASS (61.1%±4.7%, 75.4%±5.0% and 82.1%±2.1%, respectively). Moreover, larger TCV/TV (total cathode volume/total volume) for HAB led to higher current and ARG removal. The ARG removal efficiency and current at TCV/TV of 0.15 were 39.2%±3.7% and 28.30±1.48 mA, respectively. They were significantly increased to 62.1%±2.0% and 34.55±0.83 mA at TCV/TV of 0.25. These results show that HAB system could be used to effectively treat real wastewater. Copyright © 2015. Published by Elsevier B.V.

Integration of ceramic membrane and compressed air-assisted solvent extraction (CASX) for metal recovery.

PubMed

Li, Chi-Wang; Chiu, Chun-Hao; Lee, Yu-Cheng; Chang, Chia-Hao; Lee, Yu-Hsun; Chen, Yi-Ming

2010-01-01

In our previous publications, compressed air-assisted solvent extraction process (CASX) was developed and proved to be kinetically efficient process for metal removal. In the current study, CASX with a ceramic MF membrane integrated for separation of spent solvent was employed to remove and recover metal from wastewater. MF was operated either in crossflow mode or dead-end with intermittent flushing mode. Under crossflow mode, three distinct stages of flux vs. TMP (trans-membrane pressure) relationship were observed. In the first stage, flux increases with increasing TMP which is followed by the stage of stable flux with increasing TMP. After reaching a threshold TMP which is dependent of crossflow velocity, flux increases again with increasing TMP. At the last stage, solvent was pushed through membrane pores as indicated by increasing permeate COD. In dead-end with intermittent flushing mode, an intermittent flushing flow (2 min after a 10-min or a 30-min dead-end filtration) was incorporated to reduce membrane fouling by flush out MSAB accumulated on membrane surface. Effects of solvent concentration and composition were also investigated. Solvent concentrations ranging from 0.1 to 1% (w/w) have no adverse effect in terms of membrane fouling. However, solvent composition, i.e. D(2)EHPA/kerosene ratio, shows impact on membrane fouling. The type of metal extractants employed in CASX has significant impact on both membrane fouling and the quality of filtrate due to the differences in their viscosity and water solubility. Separation of MSAB was the limiting process controlling metal removal efficiency, and the removal efficiency of Cd(II) and Cr(VI) followed the same trend as that for COD.

Destruction of PCDD/Fs by SCR from flue gases of municipal waste incinerator and metal smelting plant.

PubMed

Chang, Moo Been; Chi, Kai Hsien; Chang, Shu Hao; Yeh, Jhy Wei

2007-01-01

Partitioning of PCDD/F congeners between vapor/solid phases and removal and destruction efficiencies achieved with selective catalytic reduction (SCR) system for PCDD/Fs at an existing municipal waste incinerator (MWI) and metal smelting plant (MSP) in Taiwan are evaluated via stack sampling and analysis. The MWI investigated is equipped with electrostatic precipitators (EP, operating temperature: 230 degrees C), wet scrubbers (WS, operating temperature: 70 degrees C) and SCR (operating temperature: 220 degrees C) as major air pollution control devices (APCDs). PCDD/F concentration measured at stack gas of the MWI investigated is 0.728 ng-TEQ/Nm(3). The removal efficiency of WS+SCR system for PCDD/Fs reaches 93% in the MWI investigated. The MSP investigated is equipped with EP (operating temperature: 240 degrees C) and SCR (operating temperature: 290 degrees C) as APCDs. The flue gas sampling results also indicate that PCDD/F concentration treated with SCR is 1.35 ng-TEQ/Nm(3). The SCR system adopted in MSP can remove 52.3% PCDD/Fs from flue gases (SCR operating temperature: 290 degrees C, Gas flow rate: 660 kN m(3)/h). In addition, the distributions of PCDD/F congeners observed in the flue gases of the MWI and MSP investigated are significantly different. This study also indicates that the PCDD/F congeners measured in the flue gases of those two facilities are mostly distributed in vapor phase prior to the SCR system and shift to solid phase (vapor-phase PCDD/Fs are effectively decomposed) after being treated with catalyst. Besides, the results also indicate that with SCR highly chlorinated PCDD/F congeners can be transformed to lowly chlorinated PCDD/F congeners probably by dechlorination, while the removal efficiencies of vapor-phase PCDD/Fs increase with increasing chlorination.

Treatment and Energy Valorisation of an Agro-Industrial Effluent in Upflow Anaerobic Sludge Reactor (UASB)

NASA Astrophysics Data System (ADS)

Martins, Ramiro; Boaventura, Rui; Paulista, Larissa

2017-12-01

The accelerated growth of the population brings with it an increase in the generation of agro-industrial effluents. The inadequate discharge of these effluents significantly affects the quality of water resources. In this way, it becomes important to invest in treatment processes for agro-industrial effluents, particularly low-cost ones. In this context, the present study includes the design and construction of an UASB reactor and optimization of the anaerobic digestion treatment of the raw effluent from sweet chestnut production in the agro-industrial company Sortegel. The efficiency of the system was evaluated through the determination / monitoring of oxygen chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), biogas production rate and quality (% methane). The reactor was fed for 25 weeks and operated under mesophilic conditions (temperature 30-40 °C). Different values were tested for the hydraulic retention time (HRT) and volumetric flow rate (VF): 0.66 days (VF=1509 L.m-3.d-1); 1.33 days (VF=755 L.m-3.d-1); 2.41 d days (VF=415 L.m-3.d-1). The average COD removal efficiency reached values of 69%, 82% and 75%, respectively, and simultaneously the associated BOD5 removal efficiency was 84%, 91% and 70%. As regards TSS, removal values were 78%, 94% and 63%. In addition, high methane production rates were obtained, between 2500 and 4800 L CH4.kg-1 COD removed d-1. For all the hydraulic retention times tested, high concentrations of methane in the biogas were recorded: 66-75%, 70% and 75% for HRT of 0.66, 1.33 and 2.41 days, respectively.

Using one filter stage of unsaturated/saturated vertical flow filters for nitrogen removal and footprint reduction of constructed wetlands.

PubMed

Morvannou, Ania; Troesch, Stéphane; Esser, Dirk; Forquet, Nicolas; Petitjean, Alain; Molle, Pascal

2017-07-01

French vertical flow constructed wetlands (VFCW) treating raw wastewater have been developed successfully over the last 30 years. Nevertheless, the two-stage VFCWs require a total filtration area of 2-2.5 m 2 /P.E. Therefore, implementing a one-stage system in which treatment performances reach standard requirements is of interest. Biho-Filter ® is one of the solutions developed in France by Epur Nature. Biho-Filter ® is a vertical flow system with an unsaturated layer at the top and a saturated layer at the bottom. The aim of this study was to assess this new configuration and to optimize its design and operating conditions. The hydraulic functioning and pollutant removal efficiency of three different Biho-Filter ® plants commissioned between 2011 and 2012 were studied. Outlet concentrations of the most efficient Biho-Filter ® configuration are 70 mg/L, 15 mg/L, 15 mg/L and 25 mg/L for chemical oxygen demand (COD), 5-day biological oxygen demand (BOD 5 ), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN), respectively. Up to 60% of total nitrogen is removed. Nitrification efficiency is mainly influenced by the height of the unsaturated zone and the recirculation rate. The optimum recirculation rate was found to be 100%. Denitrification in the saturated zone works at best with an influent COD/NO 3 -N ratio at the inflet of this zone larger than 2 and a hydraulic retention time longer than 0.75 days.

Removal of antibiotics in wastewater: Effect of hydraulic and solid retention times on the fate of tetracycline in the activated sludge process.

PubMed

Kim, Sungpyo; Eichhorn, Peter; Jensen, James N; Weber, A Scott; Aga, Diana S

2005-08-01

A study was conducted to examine the influence of hydraulic retention time (HRT) and solid retention time (SRT) on the removal of tetracycline in the activated sludge processes. Two lab-scale sequencing batch reactors (SBRs) were operated to simulate the activated sludge process. One SBR was spiked with 250 microg/L tetracycline, while the other SBR was evaluated at tetracycline concentrations found in the influent of the wastewater treatment plant (WWTP) where the activated sludge was obtained. The concentrations of tetracyclines in the influent of the WWTP ranged from 0.1 to 0.6 microg/L. Three different operating conditions were applied during the study (phase 1-HRT: 24 h and SRT: 10 days; phase 2-HRT: 7.4 h and SRT: 10 days; and phase 3-HRT: 7.4 h and SRT: 3 days). The removal efficiency of tetracycline in phase 3 (78.4 +/- 7.1%) was significantly lower than that observed in phase 1 (86.4 +/- 8.7%) and phase 2 (85.1 +/- 5.4%) at the 95% confidence level. The reduction of SRT in phase 3 while maintaining a constant HRT decreased tetracycline removal efficiency. Sorption kinetics reached equilibrium within 24 h. Batch equilibrium experiments yielded an adsorption coefficient (Kads) of 8400 +/- 500 mL/g and a desorption coefficient (Kdes) of 22 600 +/- 2200 mL/g. No evidence of biodegradation for tetracycline was observed during the biodegradability test, and sorption was found to be the principal removal mechanism of tetracycline in activated sludge.

High-strength fermentable wastewater reclamation through a sequential process of anaerobic fermentation followed by microalgae cultivation.

PubMed

Qi, Wenqiang; Chen, Taojing; Wang, Liang; Wu, Minghong; Zhao, Quanyu; Wei, Wei

2017-03-01

In this study, the sequential process of anaerobic fermentation followed by microalgae cultivation was evaluated from both nutrient and energy recovery standpoints. The effects of different fermentation type on the biogas generation, broth metabolites' composition, algal growth and nutrients' utilization, and energy conversion efficiencies for the whole processes were discussed. When the fermentation was designed to produce hydrogen-dominating biogas, the total energy conversion efficiency (TECE) of the sequential process was higher than that of the methane fermentation one. With the production of hydrogen in anaerobic fermentation, more organic carbon metabolites were left in the broth to support better algal growth with more efficient incorporation of ammonia nitrogen. By applying the sequential process, the heat value conversion efficiency (HVCE) for the wastewater could reach 41.2%, if methane was avoided in the fermentation biogas. The removal efficiencies of organic metabolites and NH 4 + -N in the better case were 100% and 98.3%, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bioremoval of humic acid from water by white rot fungi: exploring the removal mechanisms.

PubMed

Zahmatkesh, M; Spanjers, H; Toran, M J; Blánquez, P; van Lier, J B

2016-12-01

Twelve white rot fungi (WRF) strains were screened on agar plates for their ability to bleach humic acid (HA). Four fungal strains were selected and tested in liquid media for removal of HA. Bioremediation was investigated by HA color removal and changes in the concentration and molecular size distribution of HA by size exclusion chromatography. Trametes versicolor and Phanerochaete chrysosporium showed the highest HA removal efficiency, reaching about 80%. Laccase and manganese peroxidase were measured as extracellular enzymes and their relation to the HA removal by WRF was investigated. Results indicated that nitrogen limitation could enhance the WRF extracellular enzyme activity, but did not necessarily increase the HA removal by WRF. The mechanism of bioremediation by WRF was shown to involve biosorption of HA by fungal biomass and degradation of HA to smaller molecules. Also, contradicting previous reports, it was shown that the decolorization of HA by WRF could not necessarily be interpreted as degradation of HA. Biosorption experiments revealed that HA removal by fungal biomass is dependent not only on the amount of biomass as the sorbent, but also on the fungal species. The involvement of cytochrome P450 (CYP) enzymes was confirmed by comparing the HA removal capability of fungi with and without the presence of a CYP inhibitor. The ability of purified laccase from WRF to solely degrade HA was proven and the importance of mediators was also demonstrated.

Rapid startup and high rate nitrogen removal from anaerobic sludge digester liquor using a SNAP process.

PubMed

Qiao, Sen; Nishiyama, Takashi; Fujii, Tatsuo; Bhatti, Zafar; Furukawa, Kenji

2012-02-01

In this study, a single-stage autotrophic nitrogen removal reactor, packed with a novel acrylic fiber biomass carrier material (Biofix), was applied for nitrogen removal from sludge digester liquor. For rapid start-up, conventional activated sludge was added to the reactor soon after the attachment of anammox biomass on the Biofix carriers, which allowed conventional activated sludge to form a protective layer of biofilm around the anammox biomass. The Nitrogen removal efficiency reached 75% within 1 week at a nitrogen loading rate of 0.46 kg-N/m(3)/day for synthetic wastewater treatment. By the end of the synthetic wastewater treatment period, the maximum nitrogen removal rate had increased to 0.92 kg-N/m(3)/day at a nitrogen loading rate of 1.0 kg-N/m(3)/day. High nitrogen removal rate was also achieved during the actual raw digester liquor treatment with the highest nitrogen removal rate being 0.83 kg-N/m(3)/day at a nitrogen loading rate of 0.93 kg-N/m(3)/day. The thick biofilm on Biofix carriers allowed anammox bacteria to survive under high DO concentration of 5-6 mg/l resulting in stable and high nitrogen removal performance. FISH and CLSM analysis demonstrated that anammox bacteria coexisted and surrounded by ammonium oxidizing bacteria.

Pyridinium-functionalized magnetic mesoporous silica nanoparticles as a reusable adsorbent for phosphate removal from aqueous solution.

PubMed

Ma, Fang; Du, Hongtao; Li, Ronghua; Zhang, Zengqiang

In this work, pyridinium-functionalized silica nanoparticles adsorbent (PC/SiO2/Fe3O4) was synthesized for phosphate removal from aqueous solutions. The removal efficiency of phosphate on the PC/SiO2/Fe3O4 was carried out and investigated under various conditions such as pH, contact temperature and initial concentration. The results showed that the adsorption equilibrium could be reached within 10 min, which fitted a Langmuir isotherm model, with maximum adsorption capacity of 94.16 mg/g, and the kinetic data were fitted well by pseudo-second-order and intra-particle diffusion models. Phosphate loaded on the adsorbents could be easily desorbed with 0.2 mol/L of NaOH, and the adsorbents showed good reusability. The adsorption capacity was still around 50 mg/g after 10 times of reuse. All the results demonstrated that this pyridinium-functionalized mesoporous material could be used for the phosphate removal from aqueous solution and it was easy to collect due to its magnetic properties.

Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch.

PubMed

Guo, Chang-Zi; Fu, Wei; Chen, Xue-Mei; Peng, Dang-Cong; Jin, Peng-Kang

2013-07-01

Oxidation-ditch operation modes were simulated using sequencing batch reactors (SBRs) with alternate stirring and aerating. The nitrogen-removal efficiencies and nitrifying characteristics of two aeration modes, point aeration and step aeration, were investigated. Under the same air-supply capacity, oxygen dissolved more efficiently in the system with point aeration, forming a larger aerobic zone. The nitrifying effects were similar in point aeration and step aeration, where the average removal efficiencies of NH4(+) N were 98% and 96%, respectively. When the proportion of anoxic and oxic zones was 1, the average removal efficiencies of total nitrogen (TN) were 45% and 66% under point aeration and step aeration, respectively. Step aeration was more beneficial to both anoxic denitrification and simultaneous nitrification and denitrification (SND). The maximum specific ammonia-uptake rates (AUR) of point aeration and step aeration were 4.7 and 4.9 mg NH4(+)/(gMLVSS h), respectively, while the maximum specific nitrite-uptake rates (NUR) of the two systems were 7.4 and 5.3 mg NO2(-)-N/(gMLVSS h), respectively. The proportions of ammonia-oxidizing bacteria (AOB) to all bacteria were 5.1% under point aeration and 7.0% under step aeration, and the proportions of nitrite-oxidizing bacteria (NOB) reached 6.5% and 9.0% under point and step aeration, respectively. The dominant genera of AOB and NOB were Nitrosococcus and Nitrospira, which accounted for 90% and 91%, respectively, under point aeration, and the diversity of nitrifying bacteria was lower than under step aeration. Point aeration was selective of nitrifying bacteria. The abundance of NOB was greater than that of AOB in both of the operation modes, and complete transformation of NH4(+) N to NO3(-)-N was observed without NO2(-)-N accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Volatile organic compounds emission control in industrial pollution source using plasma technology coupled with F-TiO2/γ-Al2O3.

PubMed

Zhu, Tao; Chen, Rui; Xia, Ni; Li, Xiaoyang; He, Xianxian; Zhao, Wenjuan; Carr, Tim

2015-01-01

Volatile organic compounds' (VOCs) effluents, which come from many industries, are triggering serious environmental problems. As an emerging technology, non-thermal plasma (NTP) technology is a potential technology for VOCs emission control. NTP coupled with F-TiO2/γ-Al2O3 is used for toluene removal from a gaseous influent at normal temperature and atmospheric pressure. NTP is generated by dielectric barrier discharge, and F-TiO2/γ-Al2O3 can be prepared by sol-gel method in the laboratory. In the experiment, the different packed materials were packed into the plasma reactor, including γ-Al2O3, TiO2/γ-Al2O3 and F-TiO2/γ-Al2O3. Through a series of characterization methods such as X-ray diffraction, scanning electronic microscopy and Brunner-Emmet-Teller measurements, the results show that the particle size distribution of F-TiO2 is relatively smaller than that of TiO2, and the pore distribution of F-TiO2 is more uniformly distributed than that of TiO2. The relationships among toluene removal efficiency, reactor input energy density, and the equivalent capacitances of air gap and dielectric barrier layer were investigated. The results show that the synergistic technology NTP with F-TiO2/γ-Al2O3 resulted in greater enhancement of toluene removal efficiency and energy efficiency. Especially, when packing with F-TiO2/γ-Al2O3 in NTP reactor, toluene removal efficiency reaches 99% and higher. Based on the data analysis of Fourier Transform Infrared Spectroscopy, the experimental results showed that NTP reactor packed with F-TiO2/γ-Al2O3 resulted in a better inhibition for by-products formation effectively in the gas exhaust.

Enhanced Nutrients Removal Using Reeds Straw as Carbon Source in a Laboratory Scale Constructed Wetland.

PubMed

Wang, Tong; Wang, Haiyan; Chang, Yang; Chu, Zhaosheng; Zhao, Yaqian; Liu, Ranbin

2018-05-27

The low carbon/nitrogen (C/N) ratio and high nitrate content characteristics of agricultural runoff restricted the nitrogen removal in constructed wetlands (CWs). To resolve such problems, the economically- and easily-obtained Phragmites Australis (reeds) litters were applied and packed in the surface layer of a surface flow CW as external carbon sources. The results demonstrated that the introduction of the reeds straw increased the C concentration as a result of their decomposition during the CW operation, which will help the denitrification in the ensuing operation of an entire 148 days. The total nitrogen (TN) and Chemical Oxygen Demand (COD) () in the effluent reached the peak level of 63.2 mg/L and 83 mg/L at the fourth and the second day, respectively. Subsequently, the pollutants in the CW that were filled with straw decreased rapidly and achieved a stable removal after 13 days of operation. Moreover, the present study showed that the N removal efficiency increased with the increase of the hydraulic retention time (HRT). Under the HRT of four days, the CW presented 74.1 ± 6%, 87.4 ± 6% and 56.0 ± 6% removal for TN, NO₃⁻, and TP, respectively.

In-situ Adsorption-Biological Combined Technology Treating Sediment Phosphorus in all Fractions

NASA Astrophysics Data System (ADS)

Zhang, Y.; Wang, C.; He, F.; Liu, B.; Xu, D.; Xia, S.; Zhou, Q.; Wu, Z.

2016-07-01

The removal efficiency of sediment phosphorus (P) in all fractions with in-situ adsorption-biological combined technology was studied in West Lake, Hangzhou, China. The removal amounts of sediment Ca-P, Fe/Al-P, IP, OP and TP by the combined effect of PCFM (Porous ceramic filter media) and V. spiralis was 61 mg/kg, 249 mg/kg, 318 mg/kg, 85 mg/kg and 416 mg/kg, respectively, and the corresponding removing rate reached 10.5%, 44.6%, 27.5%, 30.6% and 29.2%. This study suggested that the combination of PCFM and V. spiralis could achieve a synergetic sediment P removal because the removal rates of the combinations were higher than the sum of that of PCFM and macrophytes used separately. From analysis of sediment microbial community and predicted function, we found that the combined PCFM and V. spiralis enhanced the function of P metabolism by increasing specific genus that belong to phylum Firmicutes and Nitrospirae. Thus it can be seen the in-situ adsorption-biological combined technology could be further applied to treat internal P loading in eutrophic waters.

In-situ Adsorption-Biological Combined Technology Treating Sediment Phosphorus in all Fractions

PubMed Central

Zhang, Y.; Wang, C.; He, F.; Liu, B.; Xu, D.; Xia, S.; Zhou, Q.; Wu, Z.

2016-01-01

The removal efficiency of sediment phosphorus (P) in all fractions with in-situ adsorption-biological combined technology was studied in West Lake, Hangzhou, China. The removal amounts of sediment Ca-P, Fe/Al-P, IP, OP and TP by the combined effect of PCFM (Porous ceramic filter media) and V. spiralis was 61 mg/kg, 249 mg/kg, 318 mg/kg, 85 mg/kg and 416 mg/kg, respectively, and the corresponding removing rate reached 10.5%, 44.6%, 27.5%, 30.6% and 29.2%. This study suggested that the combination of PCFM and V. spiralis could achieve a synergetic sediment P removal because the removal rates of the combinations were higher than the sum of that of PCFM and macrophytes used separately. From analysis of sediment microbial community and predicted function, we found that the combined PCFM and V. spiralis enhanced the function of P metabolism by increasing specific genus that belong to phylum Firmicutes and Nitrospirae. Thus it can be seen the in-situ adsorption-biological combined technology could be further applied to treat internal P loading in eutrophic waters. PMID:27418242

Evaluation of ionic air purifiers for reducing aerosol exposure in confined indoor spaces.

PubMed

Grinshpun, S A; Mainelis, G; Trunov, M; Adhikari, A; Reponen, T; Willeke, K

2005-08-01

Numerous techniques have been developed over the years for reducing aerosol exposure in indoor air environments. Among indoor air purifiers of different types, ionic emitters have gained increasing attention and are presently used for removing dust particles, aeroallergens and airborne microorganisms from indoor air. In this study, five ionic air purifiers (two wearable and three stationary) that produce unipolar air ions were evaluated with respect to their ability to reduce aerosol exposure in confined indoor spaces. The concentration decay of respirable particles of different properties was monitored in real time inside the breathing zone of a human manikin, which was placed in a relatively small (2.6 m3) walk-in chamber during the operation of an ionic air purifier in calm air and under mixing air condition. The particle removal efficiency as a function of particle size was determined using the data collected with a size-selective optical particle counter. The removal efficiency of the more powerful of the two wearable ionic purifiers reached about 50% after 15 min and almost 100% after 1.5 h of continuous operation in the chamber under calm air conditions. In the absence of external ventilation, air mixing, especially vigorous one (900 CFM), enhanced the air cleaning effect. Similar results were obtained when the manikin was placed inside a partial enclosure that simulated an aircraft seating configuration. All three stationary ionic air purifiers tested in this study were found capable of reducing the aerosol concentration in a confined indoor space. The most powerful stationary unit demonstrated an extremely high particle removal efficiency that increased sharply to almost 90% within 5-6 min, reaching about 100% within 10-12 min for all particle sizes (0.3-3 microm) tested in the chamber. For the units of the same emission rate, the data suggest that the ion polarity per se (negative vs. positive) does not affect the performance but the ion emission rate does. The effects of particle size (within the tested range) and properties (NaCl, PSL, Pseudomonas fluorescens bacteria) as well as the effects of the manikin's body temperature and its breathing on the ionic purifier performance were either small or insignificant. The data suggest that the unipolar ionic air purifiers are particularly efficient in reducing aerosol exposure in the breathing zone when used inside confined spaces with a relatively high surface-to-volume ratio. Ionic air purifiers have become increasingly popular for removing dust particles, aeroallergens and airborne microorganisms from indoor air in various settings. While the indoor air cleaning effect, resulting from unipolar and bipolar ion emission, has been tested by several investigators, there are still controversial claims (favorable and unfavorable) about the performance of commercially available ionic air purifiers. Among the five tested ionic air purifiers (two wearable and three stationary) producing unipolar air ions, the units with a higher ion emission rate provided higher particle removal efficiency. The ion polarity (negative vs. positive), the particle size (0.3-3 microm) and properties (NaCl, PSL, Pseudomonas fluorescens bacteria), as well as the body temperature and breathing did not considerable affected the ionization-driven particle removal. The data suggest that the unipolar ionic air purifiers are particularly efficient in reducing aerosol exposure in the breathing zone when they are used inside confined spaces with a relatively high surface-to-volume ratio (such as automobile cabins, aircraft seating areas, bathrooms, cellular offices, small residential rooms, and animal confinements). Based on our experiments, we proposed that purifiers with a very high ion emission rate be operated in an intermittent mode if used indoors for extended time periods. As the particles migrate to and deposit on indoor surfaces during the operation of ionic air purifiers, some excessive surface contamination may occur, which introduces the need of periodic cleaning these surfaces.

Simplified greywater treatment systems: Slow filters of sand and slate waste followed by granular activated carbon.

PubMed

Zipf, Mariah Siebert; Pinheiro, Ivone Gohr; Conegero, Mariana Garcia

2016-07-01

One of the main actions of sustainability that is applicable to residential, commercial, and public buildings is the rational use of water that contemplates the reuse of greywater as one of the main options for reducing the consumption of drinking water. Therefore, this research aimed to study the efficiencies of simplified treatments for greywater reuse using slow sand and slow slate waste filtration, both followed by granular activated carbon filters. The system monitoring was conducted over 28 weeks, using analyses of the following parameters: pH, turbidity, apparent color, biochemical oxygen demand (BOD), chemical oxygen demand (COD), surfactants, total coliforms, and thermotolerant coliforms. The system was run at two different filtration rates: 6 and 2 m(3)/m(2)/day. Statistical analyses showed no significant differences in the majority of the results when filtration rate changed from 6 to 2 m(3)/m(2)/day. The average removal efficiencies with regard to the turbidity, apparent color, COD and BOD were 61, 54, 56, and 56%, respectively, for the sand filter, and 66, 61, 60, and 51%, respectively, for the slate waste filter. Both systems showed good efficiencies in removing surfactants, around 70%, while the pH reached values of around 7.80. The average removal efficiencies of the total and thermotolerant coliforms were of 61 and 90%, respectively, for the sand filter, and 67 and 80%, respectively, for the slate waste filter. The statistical analysis found no significant differences between the responses of the two systems, which attest to the fact that the slate waste can be a substitute for sand. The maximum levels of efficiency were high, indicating the potential of the systems, and suggesting their optimization in order to achieve much higher average efficiencies. Copyright © 2016 Elsevier Ltd. All rights reserved.

The role of dynamic surface water-groundwater exchange on streambed denitrification in a first-order, low-relief agricultural watershed

NASA Astrophysics Data System (ADS)

Rahimi, Mina; Essaid, Hedeff I.; Wilson, John T.

2015-12-01

The role of temporally varying surface water-groundwater (SW-GW) exchange on nitrate removal by streambed denitrification was examined along a reach of Leary Weber Ditch (LWD), Indiana, a small, first-order, low-relief agricultural watershed within the Upper Mississippi River basin, using data collected in 2004 and 2005. Stream stage, GW heads (H), and temperatures (T) were continuously monitored in streambed piezometers and stream bank wells for two transects across LWD accompanied by synoptic measurements of stream stage, H, T, and nitrate (NO3) concentrations along the reach. The H and T data were used to develop and calibrate vertical two-dimensional, models of streambed water flow and heat transport across and along the axis of the stream. Model-estimated SW-GW exchange varied seasonally and in response to high-streamflow events due to dynamic interactions between SW stage and GW H. Comparison of 2004 and 2005 conditions showed that small changes in precipitation amount and intensity, evapotranspiration, and/or nearby GW levels within a low-relief watershed can readily impact SW-GW interactions. The calibrated LWD flow models and observed stream and streambed NO3 concentrations were used to predict temporal variations in streambed NO3 removal in response to dynamic SW-GW exchange. NO3 removal rates underwent slow seasonal changes, but also underwent rapid changes in response to high-flow events. These findings suggest that increased temporal variability of SW-GW exchange in low-order, low-relief watersheds may be a factor contributing their more efficient removal of NO3.

The role of dynamic surface water-groundwater exchange on streambed denitrification in a first-order, low-relief agricultural watershed

USGS Publications Warehouse

Rahimi Kazerooni, Mina N.; Essaid, Hedeff I.; Wilson, John T.

2015-01-01

The role of temporally varying surface water-groundwater (SW-GW) exchange on nitrate removal by streambed denitrification was examined along a reach of Leary Weber Ditch (LWD), Indiana, a small, first-order, low-relief agricultural watershed within the Upper Mississippi River basin, using data collected in 2004 and 2005. Stream stage, GW heads (H), and temperatures (T) were continuously monitored in streambed piezometers and stream bank wells for two transects across LWD accompanied by synoptic measurements of stream stage, H, T, and nitrate (NO3) concentrations along the reach. The H and T data were used to develop and calibrate vertical two-dimensional, models of streambed water flow and heat transport across and along the axis of the stream. Model-estimated SW-GW exchange varied seasonally and in response to high-streamflow events due to dynamic interactions between SW stage and GW H. Comparison of 2004 and 2005 conditions showed that small changes in precipitation amount and intensity, evapotranspiration, and/or nearby GW levels within a low-relief watershed can readily impact SW-GW interactions. The calibrated LWD flow models and observed stream and streambed NO3 concentrations were used to predict temporal variations in streambed NO3 removal in response to dynamic SW-GW exchange. NO3 removal rates underwent slow seasonal changes, but also underwent rapid changes in response to high-flow events. These findings suggest that increased temporal variability of SW-GW exchange in low-order, low-relief watersheds may be a factor contributing their more efficient removal of NO3.

Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

NASA Astrophysics Data System (ADS)

Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

2016-06-01

In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients ( L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient ( β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

Sequential hydrogen and methane coproduction from sugary wastewater treatment by "CSTRHyd-UASBMet" system

NASA Astrophysics Data System (ADS)

Hao, Ping

2017-10-01

Potentiality of sequential hydrogen bioproduction from sugary wastewater treatment was investigated using continuous stirred tank reactor (CSTR) for various substrate COD concentrations and HRTs. At optimum substrate concentration of 6 g COD/L, hydrogen could be efficiently produced from CSTR with the highest production rate of 3.00 (±0.04) L/L reactor d at HRT of 6 h. The up flow anaerobic sludge bed (UASB) reactor was used for continuous methane bioproduction from the effluents of hydrogen bioproduction. At optimal HRT 12 h, methane could be produced with a production rate of 2.27 (±0.08) L/L reactor d and the COD removal efficiency reached up to the maximum 82.3%.

The removal of pharmaceuticals, personal care products, endocrine disruptors and illicit drugs during wastewater treatment and its impact on the quality of receiving waters.

PubMed

Kasprzyk-Hordern, Barbara; Dinsdale, Richard M; Guwy, Alan J

2009-02-01

A 5-month monitoring program was undertaken in South Wales in the UK to determine the fate of 55 pharmaceuticals, personal care products, endocrine disruptors and illicit drugs (PPCPs) in two contrasting wastewater plants utilising two different wastewater treatment technologies: activated sludge and trickling filter beds. The impact of treated wastewater effluent on the quality of receiving waters was also assessed. PPCPs were found to be present at high loads reaching 10kgday(-1) in the raw sewage. Concentrations of PPCPs in raw sewage were found to correlate with their usage/consumption patterns in Wales and their metabolism. The efficiency of the removal of PPCPs was found to be strongly dependent on the technology implemented in the wastewater treatment plant (WWTP). In general, the WWTP utilising trickling filter beds resulted in, on average, less than 70% removal of all 55 PPCPs studied, while the WWTP utilising activated sludge treatment gave a much higher removal efficiency of over 85%. The monitoring programme revealed that treated wastewater effluents were the main contributors to PPCPs concentrations (up to 3kg of PPCPsday(-1)) in the rivers studied. Bearing in mind that in the cases examined here the WWTP effluents were also major contributors to rivers' flows (dilution factor for the studied rivers did not exceed 23 times) the effect of WWTP effluent on the quality of river water is significant and cannot be underestimated.

Ear-like poly (acrylic acid)-activated carbon nanocomposite: A highly efficient adsorbent for removal of Cd(II) from aqueous solutions.

PubMed

Ge, Huacai; Wang, Jincui

2017-02-01

Poly (acrylic acid) modified activated carbon nanocomposite (PAA-AC) was synthesized. The structure and morphology of this nanocomposite were characterized by FTIR, SEM, TEM, XRD and Zeta potential. The adsorption of some heavy metal ions on PAA-AC was studied. The characterization results indicated that PAA-AC was a novel and ear-like nanosheet material with the thickness of about 40 nm and the diameter of about 300 nm. The adsorption results exhibited that the introduction of carboxyl groups into activated carbon evidently increased the uptake for heavy metal ions and the nanocomposite had maximum uptake for Cd(II). Various variables affecting adsorption of PAA-AC for Cd(II) were systematically explored. The maximum capacity and equilibrium time for adsorption of Cd(II) by PAA-AC were 473.2 mg g -1 and 15 min. Moreover, the removal of Cd(II) for real electroplating wastewater by PAA-AC could reach 98.5%. These meant that the removal of Cd(II) by PAA-AC was highly efficient and fast. The sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively. The adsorption mainly was a chemical process by chelation. Thermodynamic studies revealed that the adsorption was a spontaneous and endothermic process. The results revealed that PAA-AC could be considered as a potential candidate for Cd(II) removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reductions in fish-community contamination following lowhead dam removal linked more to shifts in food-web structure than sediment pollution.

PubMed

Davis, Robert P; Sullivan, S Mažeika P; Stefanik, Kay C

2017-12-01

Recent increases in dam removals have prompted research on ecological and geomorphic river responses, yet contaminant dynamics following dam removals are poorly understood. We investigated changes in sediment concentrations and fish-community body burdens of mercury (Hg), selenium (Se), polychlorinated biphenyls (PCB), and chlorinated pesticides before and after two lowhead dam removals in the Scioto and Olentangy Rivers (Columbus, Ohio). These changes were then related to documented shifts in fish food-web structure. Seven study reaches were surveyed from 2011 to 2015, including controls, upstream and downstream of the previous dams, and upstream restored vs. unrestored. For most contaminants, fish-community body burdens declined following dam removal and converged across study reaches by the last year of the study in both rivers. Aldrin and dieldrin body burdens in the Olentangy River declined more rapidly in the upstream-restored vs. the upstream-unrestored reach, but were indistinguishable by year three post dam removal. No upstream-downstream differences were observed in body burdens in the Olentangy River, but aldrin and dieldrin body burdens were 138 and 148% higher, respectively, in downstream reaches than in upstream reaches of the Scioto River following dam removal. The strongest relationships between trophic position and body burdens were observed with PCBs and Se in the Scioto River, and with dieldrin in the Olentangy River. Food-chain length - a key measure of trophic structure - was only weakly related to aldrin body burdens, and unrelated to other contaminants. Overall, we demonstrate that lowhead dam removal may effectively reduce ecosystem contamination, largely via shifts in fish food-web dynamics versus sediment contaminant concentrations. This study presents some of the first findings documenting ecosystem contamination following dam removal and will be useful in informing future dam removals. Copyright © 2017 Elsevier Ltd. All rights reserved.

In-situ synthesis of SiO2@MOF composites for high-efficiency removal of aniline from aqueous solution

NASA Astrophysics Data System (ADS)

Han, Tongtong; Li, Caifeng; Guo, Xiangyu; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

2016-12-01

A series of SiO2@aluminum-MOF(MIL-68) composites with different SiO2 loadings have been synthesized by a simple and mild compositing strategy for high-efficiency removal of aniline. As evidenced from SEM and TEM images as well as the particle size distribution, the incorporation of SiO2 can improve the dispersity of MIL-68(Al) in composites, and result in the smaller particle size than that of pristine MIL-68(Al). Besides, the adsorption of aniline over SiO2, MIL-68(Al), the physical mixture of these two materials, and SiO2@MIL-68(Al) composites was investigated comparatively, demonstrating a relatively high adsorption capacity (531.9 mg g-1) of 7% SiO2@MIL-68(Al) towards aniline. Combining the ultrafast adsorption dynamics (reaching equilibrium within 40 s) and great reusability, 7% SiO2@MIL-68(Al) shows excellent adsorption performance. This indicates that the SiO2@MIL-68(Al) composites possess great potential applications as a kind of fascinating adsorbent in water pollution protection.

Flocculation characteristics of polyacrylamide grafted cellulose from Phyllostachys heterocycla: An efficient and eco-friendly flocculant.

PubMed

Liu, Hongyi; Yang, Xiaogang; Zhang, Yong; Zhu, Hangcheng; Yao, Juming

2014-08-01

This work presents a synthesis process and flocculation characteristics of an eco-friendly flocculant based on bamboo pulp cellulose (BPC) from Phyllostachys heterocycla. Ployacrylamide (PAM) was grafted onto the BPC by free-radical graft copolymerization in homogeneous aqueous solution. The optimal synthesis conditions of the bamboo pulp cellulose-graft-ployacrylamide flocculant (BPC-g-PAM) and its performance on wastewater treatments were investigated. A UV-based method was used to rapidly determine the degree of substitution (DS) of BPC. The results showed that, under the optimal synthesis conditions, the obtained BPC-g-PAM held a grafting ratio of 43.8% and DS of 1.31. Turbidity removal of the product reached 98.0% accompanying with the significant flocculation and sedimentation in target suspensions. The flocculation mechanism was explored by means of zeta potential method. For negatively charged contaminants, like kaolin clay particles, the BPC-g-PAM could remove the contaminants efficiently via bridging and charge neutralization in acidic or neutral environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improvements in Fabrication of 3D SU-8 Prisms for Low-Coupling-Loss Interconnections Between Fibers and Waveguides

NASA Astrophysics Data System (ADS)

Nguyen, Minh-Hang; Chu, Thi-Xuan; Nguyen, Long; Nguyen, Hai-Binh; Lee, Chun-Wei; Tseng, Fan-Gang; Chen, Te-Chang; Lee, Ming-Chang

2016-11-01

Fabrication of three-dimensional (3D) SU-8 (an epoxy-based negative photoresist from MicroChem) prisms as low-loss couplers for interconnection between optical components, particularly optical fibers and silicon-on-isolator waveguides (SOI WGs), which have mismatched mode sizes, has been investigated. With an interfacial structure formed by a 3D SU-8 prism partly overlaying an SOI WG end with a portion of buried oxide (BOX) removed under the interface, low-loss coupling is ensured and the transmission efficiency can reach 70%. To fabricate these 3D SU-8 prisms, a simple method with two photolithography steps was used for SU-8 hinges and CYTOP (an amorphous fluoropolymer from AGC Chemicals) prism windows, with mild soft and hard bakes, to define the prism profiles with diluted SU-8 filled in the CYTOP prism windows. A buffered oxide etchant is used to remove BOX parts under the interfaces. Some of the fabricated structures were tested, demonstrating the contribution of overlaying SU-8 prisms to the transmission efficiency of optical interconnections between fibers and SOI WGs.

Laboratory-scale column study for remediation of TCE-contaminated aquifers using three-section controlled-release potassium permanganate barriers.

PubMed

Yuan, Baoling; Li, Fei; Chen, Yanmei; Fu, Ming-Lai

2013-05-01

A laboratory-scale study with a sand column was designed to simulate trichloroethylene (TCE) pollution in the aquifer environment with three-section controlled-release potassium permanganate (CRP) barriers. The main objective of this study was to evaluate the feasibility of CRP barriers in remediation of TCE in aquifers in a long-term and controlled manner. CRP particles with a 1:3 molar ratio of KMnO4 to stearic acid showed the best controlled-release properties in pure water, and the theoretical release time was 138.5 days. The results of TCE removal in the test column indicated that complete removal efficiency of TCE in a sand column by three-section CRP barriers could be reached within 15 days. The molar ratio of KMnO4 to TCE in the three-section CRP barriers was 16:1, which was much lower than 82:1 as required when KMnO4 solution is used directly to achieve complete destruction of TCE. This result revealed that the efficiency of CRP for remediation of TCE was highly improved after encapsulation.

An Efficient and Reproducible Protocol for Distraction Osteogenesis in a Rat Model Leading to a Functional Regenerated Femur.

PubMed

Pithioux, Martine; Roseren, Flavy; Jalain, Christian; Launay, Franck; Charpiot, Philippe; Chabrand, Patrick; Roffino, Sandrine; Lamy, Edouard

2017-10-23

This protocol describes the use of a newly developed external fixator for distraction osteogenesis in a rat femoral model. Distraction osteogenesis (DO) is a surgical technique leading to bone regeneration after an osteotomy. The osteotomized extremities are moved away from each other by gradual distraction to reach the desired elongation. This procedure is widely used in humans for lower and upper limb lengthening, treatment after a bone nonunion, or the regeneration of a bone defect following surgery for bone tumor excision, as well as in maxillofacial reconstruction. Only a few studies clearly demonstrate the efficiency of their protocol in obtaining a functional regenerated bone, i.e., bone that will support physiological weight-bearing without fracture after removal of the external fixator. Moreover, protocols for DO vary and reproducibility is limited by lack of information, making comparison between studies difficult. The aim of this study was to develop a reproducible protocol comprising an appropriate external fixator design for rat limb lengthening, with a detailed surgical technique that permits physiological weight-bearing by the animal after removal of the external fixator.

Sequential two-column electro-Fenton-photolytic reactor for the treatment of winery wastewater.

PubMed

Díez, A M; Sanromán, M A; Pazos, M

2017-01-01

The high amount of winery wastewaters produced each year makes their treatment a priority issue due to their problematic characteristics such as acid pH, high concentration of organic load and colourful compounds. Furthermore, some of these effluents can have dissolved pesticides, due to the previous grape treatments, which are recalcitrant to conventional treatments. Recently, photo-electro-Fenton process has been reported as an effective procedure to mineralize different organic contaminants and a promising technology for the treatment of these complex matrixes. However, the reactors available for applying this process are scarce and they show several limitations. In this study, a sequential two-column reactor for the photo-electro-Fenton treatment was designed and evaluated for the treatment of different pesticides, pirimicarb and pyrimethanil, used in wine production. Both studied pesticides were efficiently removed, and the transformation products were determined. Finally, the treatment of a complex aqueous matrix composed by winery wastewater and the previously studied pesticides was carried out in the designed sequential reactor. The high removals of TOC and COD reached and the low energy consumption demonstrated the efficiency of this new configuration.

Effects of dam removal on brook trout in a Wisconsin stream

USGS Publications Warehouse

Stanley, E.H.; Catalano, M.J.; Mercado-Silva, N.; Orr, C.H.

2007-01-01

Dams create barriers to fish migration and dispersal in drainage basins, and the removal of dams is often viewed as a means of increasing habitat availability and restoring migratory routes of several fish species. However, these barriers can also isolate and protect native taxa from aggressive downstream invaders. We examined fish community composition two years prior to and two years after the removal of a pair of low-head dams from Boulder Creek, Wisconsin, U.S.A. in 2003 to determine if removal of these potential barriers affected the resident population of native brook trout (Salvelinus fontinalis). Despite the presence of other taxa in the downstream reaches, and in other similar streams adjacent to the Boulder Creek (including the brown trout, Salmo trutta), no new species had colonized the Boulder Creek in the two years following dam removal. The adults catch per unit effort (CPUE) was lower and the young-of-the-year catch per unit effort (YOY CPUE) was higher in 2005 than in 2001 in all reaches, but the magnitude of these changes was substantially larger in the two dam-affected sample reaches relative to an upstream reference reach, indicating a localized effect of the removal. Total length of the adults and the YOY and the adult body condition did not vary between years or among reaches. Thus, despite changes in numbers of adults and the YOYs in some sections of the stream, the lack of new fish species invading Boulder Creek and the limited extent of population change in brook trout indicate that dam removal had a minor effect on these native salmonids in the first two years of the post-removal. Copyright ?? 2007 John Wiley & Sons, Ltd.

The use of seaweed and sugarcane bagasse for the biological treatment of metal-contaminated waters under sulfate-reducing conditions.

PubMed

Gonçalves, Márcia Monteiro Machado; de Oliveira Mello, Luiz Antonio; da Costa, Antonio Carlos Augusto

2008-03-01

When wetlands reach maximum treatment capacity to remove heavy metals, removal can still take place through precipitation as sulfide because of the biological reduction of sulfate. To achieve this goal, anaerobic conditions must be attained, a sulfate source must exist, and an adequate substrate for sulfate-reducing bacteria (SRB) is also required. In the present work, two ligneous-cellulosic materials, a brown seaweed and sugarcane bagasse, have been selected as substrates for SRB growth. Experiments were simultaneously conducted in continuous operation in two columns (0.57 L each), one containing the ligneous-cellulosic material plus inoculum and another containing only the ligneous-cellulosic material. In this work, the removal of cadmium and zinc was studied because of their presence in effluents from mining/metallurgy operations. Results obtained indicated that the inoculated reactor was able to treat the effluent more efficiently than the noninoculated reactor considering the time course of the tests.

The start-up of denitrifying phosphorus removal system by using nitrite as electron acceptor

NASA Astrophysics Data System (ADS)

Li, W.; Liu, J.; Sun, H. Z.; Fu, J. X.; Gao, Y.; Sun, J.

2017-08-01

The inoculation of short-cut denitrifying polyphosphate-accumulating organisms (DPAOs) mainly included two-phase inoculation and three-phase inoculation. The short-cut denitrifying phosphorus removal bacteria were quickly inoculated by sequencing batch reactor (SBR) to treatment domestic wastewater. The results showed that the average effluent concentration of TP was 0.85 mg/L after 132 cycles by 44 days in two-phase inoculation. The removal rates of NO2 --N, TP and COD were 94.73%, 95.47% and 89.96% after 126 cycles by 42 days in three-phase inoculation, and the effluent concentrations were separately 1.31 mg/L, 0.45 mg/L and 17.07 mg/L, which reached the first A class requirement of Urban sewage treatment plant pollutant discharge standard. It was indicated that the efficiency of three-phase inoculation was higher. Anoxic phosphorus uptake was influenced seriously by anaerobic residual carbon, and it was the difference of the two inoculations.

Improvement of the fermentability of oxalic acid hydrolysates by detoxification using electrodialysis and adsorption.

PubMed

Jeong, So-Yeon; Trinh, Ly Thi Phi; Lee, Hong-Joo; Lee, Jae-Won

2014-01-01

A two-step detoxification process consisting of electrodialysis and adsorption was performed to improve the fermentability of oxalic acid hydrolysates. The constituents of the hydrolysate differed significantly between mixed hardwood and softwood. Acetic acid and furfural concentrations were high in the mixed hardwood, whereas 5-hydroxymethylfurfural (HMF) concentration was relatively low compared with that of the mixed softwood. The removal efficiency of acetic acid reached 100% by electrodialysis (ED) process in both hydrolysates, while those of furfural and HMF showed very low, due to non-ionizable properties. Most of the remaining inhibitors were removed by XAD-4 resin. In the mixed hardwood hydrolysate without removal of the inhibitors, ethanol fermentation was not completed. Meanwhile, both ED-treated hydrolysates successfully produced ethanol with 0.08 and 0.15 g/Lh ethanol productivity, respectively. The maximum ethanol productivity was attained after fermentation with 0.27 and 0.35 g/Lh of detoxified hydrolysates, which were treated by ED, followed by XAD-4 resin. Copyright © 2013 Elsevier Ltd. All rights reserved.

Preparation of CMC-g-P(SPMA) super adsorbent hydrogels: Exploring their capacity for MB removal from waste water.

PubMed

Salama, Ahmed

2018-01-01

A novel superadsorbent anionic hydrogel was synthesized by grafting of poly (3-sulfopropyl methacrylate), P(SPMA), onto carboxymethyl cellulose (CMC). CMC-g-P(SPMA) superadsorbent hydrogel was applied as an efficient and sustainable adsorbent to remove methylene blue (MB) from waste water. Batch adsorption experiments showed that the solution pH had an obvious effect on the adsorption capacity with an optimal sorption pH at 6. The CMC-g-P(SPMA) hydrogel had rapid adsorption kinetics for MB and the adsorption equilibrium reached within 40min. The adsorption kinetics were more accurately described by pseudo second-order model and the Langmuir-fitted adsorption isotherms revealed a maximum capacity of 1675mg/g. The current anionic hydrogel is reusable as the adsorption capacity remained at 89% level after five adsorption-desorption cycles. CMC-g-P(SPMA) hydrogel was presented as a sustainable promising adsorbent with high adsorption capacity and good regenerability for effective cationic dyes removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Microbial communities in the functional areas of a biofilm reactor with anaerobic-aerobic process for oily wastewater treatment.

PubMed

Li, Jianhua; Sun, Shanshan; Yan, Ping; Fang, Li; Yu, Yang; Xiang, Yangdong; Wang, Di; Gong, Yejing; Gong, Yanjun; Zhang, Zhongzhi

2017-08-01

Microbial communities in the functional areas of biofilm reactors with large height-diameter ratio using the anaerobic-aerobic (A/O) reflux process was investigated to treat heavy oil refinery wastewater without pretreatment. In the process, chemical oxygen demand (COD) and total nitrogen (TN) removal reached 93.2% and 82.8%, and the anaerobic biofilm reactor was responsible for 95% and 99%, respectively. Areas for hydrolysis acidification and acetic acid production, methane production, and COD recovery were obvious in the anaerobic reactor. Among all areas, area for hydrolysis acidification and acetic acid production was the key factor to improve COD removal efficiency. High throughput sequencing of 16S rDNA gene showed that the native community was mainly composed of functional groups for hydrocarbon degradation, syntrophic bacteria union body, methanogenesis, nitrification, denitrification, and sulfate reduction. The deviations between predicted values and actual COD and TN removal were less than 5% in the optimal prediction model. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effects of leachate recirculation with supplemental water addition on methane production and waste decomposition in a simulated tropical landfill.

PubMed

Sanphoti, N; Towprayoon, S; Chaiprasert, P; Nopharatana, A

2006-10-01

In order to increase methane production efficiency, leachate recirculation is applied in landfills to increase moisture content and circulate organic matter back into the landfill cell. In the case of tropical landfills, where high temperature and evaporation occurs, leachate recirculation may not be enough to maintain the moisture content, therefore supplemental water addition into the cell is an option that could help stabilize moisture levels as well as stimulate biological activity. The objectives of this study were to determine the effects of leachate recirculation and supplemental water addition on municipal solid waste decomposition and methane production in three anaerobic digestion reactors. Anaerobic digestion with leachate recirculation and supplemental water addition showed the highest performance in terms of cumulative methane production and the stabilization period time required. It produced an accumulated methane production of 54.87 l/kg dry weight of MSW at an average rate of 0.58 l/kg dry weight/d and reached the stabilization phase on day 180. The leachate recirculation reactor provided 17.04 l/kg dry weight at a rate of 0.14l/kg dry weight/d and reached the stabilization phase on day 290. The control reactor provided 9.02 l/kg dry weight at a rate of 0.10 l/kg dry weight/d, and reached the stabilization phase on day 270. Increasing the organic loading rate (OLR) after the waste had reached the stabilization phase made it possible to increase the methane content of the gas, the methane production rate, and the COD removal. Comparison of the reactors' efficiencies at maximum OLR (5 kgCOD/m(3)/d) in terms of the methane production rate showed that the reactor using leachate recirculation with supplemental water addition still gave the highest performance (1.56 l/kg dry weight/d), whereas the leachate recirculation reactor and the control reactor provided 0.69 l/kg dry weight/d and 0.43 l/kg dry weight/d, respectively. However, when considering methane composition (average 63.09%) and COD removal (average 90.60%), slight differences were found among these three reactors.

Effect of humic acid on pyrene removal from water by polycation-clay mineral composites and activated carbon.

PubMed

Radian, Adi; Mishael, Yael

2012-06-05

Pyrene removal by polycation-montmorillonite (MMT) composites and granulated activated carbon (GAC) in the presence of humic acid (HA) was examined. Pyrene, HA, and sorbent interactions were characterized by FTIR, fluorescence and zeta measurements, adsorption, and column filtration experiments. Pyrene binding coefficients to the macromolecules were in the order of PVPcoS (poly-4-vinylpiridine-co-styrene) > HA > PDADMAC (poly diallyl-dimethyl-ammonium-chloride), correlating to pyrene-macromolecules compatibility. Electrostatic interactions explained the high adsorption of HA to both composites (∼100%), whereas HA adsorption by GAC was low. Pyrene removal by the composites, unlike GAC, was enhanced in the presence of HA; removal by PDADMAC-MMT increased from ∼50 (k(d) = 2.2 × 10(3) kg/L) to ∼70% (k(d) = 2.4 × 10(3) kg/L) in the presence of HA. This improvement was attributed to the adsorption of pyrene-HA complexes. PVPcoS-MMT was most efficient in removing pyrene (k(d) = 1.1 × 10(4) kg/L, >95% removal) which was explained in terms of specific π donor-π acceptor interactions. Pyrene uptake by column filters of GAC reached ∼50% and decreased to ∼30% in the presence of HA. Pyrene removal by the PVPcoS-MMT filter was significantly higher (100-85% removal), exhibiting only a small decrease in the presence of HA. The utilization of HA as an enhancing agent in pollutant removal is novel and of major importance in water treatment.

Ultrasonic and Thermal Pretreatments on Anaerobic Digestion of Petrochemical Sludge: Dewaterability and Degradation of PAHs

PubMed Central

Zhou, Jun; Xu, Weizhong; Wong, Jonathan W. C.; Yong, Xiaoyu; Yan, Binghua; Zhang, Xueying; Jia, Honghua

2015-01-01

Effects of different pretreatment methods on sludge dewaterability and polycyclic aromatic hydrocarbons (PAHs) degradation during petrochemical sludge anaerobic digestion were studied. Results showed that the total biogas production volume in the thermal pretreatment system was 4 and 5 times higher than that in the ultrasound pretreatment and in the control system, and the corresponding volatile solid removal efficiencies reached 28%, 15%, and 8%. Phenanthrene, paranaphthalene, fluoranthene, benzofluoranthene, and benzopyrene removal rates reached 43.3%, 55.5%, 30.6%, 42.9%, and 41.7%, respectively, in the thermal pretreatment system, which were much higher than those in the ultrasound pretreatment and in the control system. Moreover, capillary suction time (CST) of sludge increased after pretreatment, and then reduced after 20 days of anaerobic digestion, indicating that sludge dewaterability was greatly improved after anaerobic digestion. The decrease of protein and polysaccharide in the sludge could improve sludge dewaterability during petrochemical sludge anaerobic digestion. This study suggested that thermal pretreatment might be a promising enhancement method for petrochemical sludge solubilization, thus contributing to degradation of the PAHs, biogas production, and improvement of dewaterability during petrochemical sludge anaerobic digestion. PMID:26327510

Removal of trace nonylphenol from water in the coexistence of suspended inorganic particles and NOMs by using a cellulose-based flocculant.

PubMed

Yang, Zhen; Ren, Kexin; Guibal, Eric; Jia, Shuying; Shen, Jiachun; Zhang, Xuntong; Yang, Weiben

2016-10-01

A flocculation method was used for the removal of trace nonylphenol (NP) from synthetic surface water containing natural organic matters (humic acid, HA) and suspended inorganic particles (kaolin). A polymeric flocculant (CMCND), with enhanced cationic property and unique switchable hydrophobic/hydrophilic characteristic, was specially designed for this application. CMCND showed a high efficiency for trace NP removal, turbidity and UV254 abatements: under optimized conditions (pH: 4; T: 35 °C; dosage: 40 mg/L), the removal of NP reached up to 79%. By using dosage-pH flocculation diagrams and correlation analyses as tools, kaolin and HA were found to exert synergistic effects on NP removal, with the aid of CMCND; the synergistic effect of HA is higher due to π-π stacking. Zeta potential-dosage profiles clearly demonstrated charge neutralization predominated at pH 4, due to the strong cationic groups in the flocculant. Floc size monitoring displayed that the delayed phase transformation process (from hydrophilicity to hydrophobicity) of CMCND at 35 °C enhanced NP removal. In addition, spectral analyses clarified the interactions among CMCND, NP, kaolin and HA: charge attraction and hydrophobic interaction between CMCND and NP played the key roles. The findings are of significance for removing endocrine-disrupting chemicals in environmental remediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conceptual design and experiments of electrochemistry-flushing technology for the remediation of historically Cr(Ⅵ)-contaminated soil.

PubMed

Li, Dong; Sun, Delin; Hu, Siyang; Hu, Jing; Yuan, Xingzhong

2016-02-01

A conceptual design and experiments, electrochemistry-flushing (E-flushing), using electrochemistry to enhance flushing efficiency for the remediation of Cr(Ⅵ)-contaminated soil is presented. The rector contained three compartments vertically superposed. The upper was airtight cathode compartment containing an iron-cathode. The middle was soil layer. The bottom was anode compartment containing an iron-anode and connected to a container by circulation pumps. H2 and OH(-) ions were produced at cathode. H2 increased the gas pressure in cathode compartment and drove flushing solution into soil layer forming flushing process. OH(-) ions entered into soil layer by eletromigration and hydraulic flow to enhance the desorption of Cr(Ⅵ). High potential gradient was applied to accelerate the electromigration of desorbed Cr(Ⅵ) ions and produced joule heat to increase soil temperature to enhance Cr(Ⅵ) desorption. In anode compartment, Fe(2+) ions produced at iron-anode reduced the desorbed Cr(Ⅵ) into Cr(3+) ions, which reacted with OH(-) ions forming Cr(OH)3. Experimental results show that Cr(Ⅵ) removal efficiency of E-flushing experiments was more than double of flushing experiments and reached the maximum of removal efficiency determined by desorption kinetics. All electrochemistry processes were positively used in E-flushing technology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment of real coal gasification wastewater using a novel integrated system of anoxic hybrid two stage aerobic processes: performance and the role of pure oxygen microbubble.

PubMed

Zhuang, Haifeng; Han, Hongjun; Shan, Shengdao

2016-06-01

A novel integrated system of anoxic-pure oxygen microbubble-activated sludge reactor-moving bed biofilm reactor was employed in treatment of real coal gasification wastewater. The results showed the integrated system had efficient performance of pollutants removal in short hydraulic retention time. While pure oxygen microbubble with the flow rate of 1.5 L/h and NaHCO3 dosage ratio of 2:1 (amount NaHCO3 to NH4 (+)-N ratio, mol: mol) were used, the removal efficiencies of COD, total phenols (TPh) and NH4 (+)-N reached 90, 95, and 95 %, respectively, with the influent loading rates of 3.4 kg COD/(m(3) d), 0.81 kg TPh/(m(3) d), and 0.28 kg NH4 (+)-N/(m(3) d). With the recycle ratio of 300 %, the concentrations of NO2 (-)-N and NO3 (-)-N in effluent decreased to 12 and 59 mg/L, respectively. Meanwhile, pure oxygen microbubble significantly improved the enzymatic activities and affected the effluent organic compositions and reduced the foam expansion. Thus, the novel integrated system with efficient, stable, and economical advantages was suitable for engineering application.

Physics of grain boundaries in polycrystalline photovoltaic semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Yanfa, E-mail: yanfa.yan@utoledo.edu; Yin, Wan-Jian; Wu, Yelong

2015-03-21

Thin-film solar cells based on polycrystalline Cu(In,Ga)Se{sub 2} (CIGS) and CdTe photovoltaic semiconductors have reached remarkable laboratory efficiencies. It is surprising that these thin-film polycrystalline solar cells can reach such high efficiencies despite containing a high density of grain boundaries (GBs), which would seem likely to be nonradiative recombination centers for photo-generated carriers. In this paper, we review our atomistic theoretical understanding of the physics of grain boundaries in CIGS and CdTe absorbers. We show that intrinsic GBs with dislocation cores exhibit deep gap states in both CIGS and CdTe. However, in each solar cell device, the GBs can bemore » chemically modified to improve their photovoltaic properties. In CIGS cells, GBs are found to be Cu-rich and contain O impurities. Density-functional theory calculations reveal that such chemical changes within GBs can remove most of the unwanted gap states. In CdTe cells, GBs are found to contain a high concentration of Cl atoms. Cl atoms donate electrons, creating n-type GBs between p-type CdTe grains, forming local p-n-p junctions along GBs. This leads to enhanced current collections. Therefore, chemical modification of GBs allows for high efficiency polycrystalline CIGS and CdTe thin-film solar cells.« less

Physics of grain boundaries in polycrystalline photovoltaic semiconductors

DOE PAGES

Yan, Yanfa; Yin, Wan-Jian; Wu, Yelong; ...

2015-03-16

Thin-film solar cells based on polycrystalline Cu(In,Ga)Se 2 (CIGS) and CdTe photovoltaic semiconductors have reached remarkable laboratory efficiencies. It is surprising that these thin-film polycrystalline solar cells can reach such high efficiencies despite containing a high density of grain boundaries (GBs), which would seem likely to be nonradiative recombination centers for photo-generated carriers. In this study, we review our atomistic theoretical understanding of the physics of grain boundaries in CIGS and CdTe absorbers. We show that intrinsic GBs with dislocation cores exhibit deep gap states in both CIGS and CdTe. Although, in each solar cell device, the GBs can bemore » chemically modified to improve their photovoltaic properties. In CIGS cells, GBs are found to be Cu-rich and contain O impurities. Density-functional theory calculations reveal that such chemical changes within GBs can remove most of the unwanted gap states. In CdTe cells, GBs are found to contain a high concentration of Cl atoms. Cl atoms donate electrons, creating n-type GBs between p-type CdTe grains, forming local p-n-p junctions along GBs. This leads to enhanced current collections. In conclusion, chemical modification of GBs allows for high efficiency polycrystalline CIGS and CdTe thin-film solar cells.« less

The effect of acidic pH and presence of metals as parameters in establishing a sulfidogenic process in anaerobic reactor.

PubMed

Vieira, Bárbara F; Couto, Pâmela T; Sancinetti, Giselle P; Klein, Bernhard; van Zyl, Dirk; Rodriguez, Renata P

2016-08-23

The successful use of anaerobic reactors for bioremediation of acid mine drainage has been shown in systems with neutral pH. However, the choice of an efficient and suitable process for such wastewater must consider the capability of operating at acidic pH and in the presence of metals. This work studies the performance of an anaerobic batch reactor, under conditions of varying initial pH for its efficiencies in sulfate removal and metal precipitation from synthetic acid mine drainage. The chemical oxygen demand/sulfate (COD/SO4(2-)) ratio used was 1.00, with ethanol chosen as the only energy and carbon source. The initial pH of the synthetic drainage was progressively set from 7.0 to 4.0 to make it as close as possible to that of real acid mine drainage. Metals were also added starting with iron, zinc, and finally copper. The effectiveness of sulfate and COD removal from the synthetic acid mine drainage increased as the initial pH was reduced. The sulfate removal increased from 38.5 ± 3.7% to 52.2 ± 3%, while the removal of organic matter started at 91.7 ± 2.4% and ended at 99 ± 1%. These results indicate that the sulfate reducing bacteria (SRB) community adapted to lower pH values. The metal removal observed was 88 ± 7% for iron, 98.0 ± 0.5% for zinc and 99 ± 1% for copper. At this stage, an increase in the sulfate removal was observed, which reaches up to 82.2 ± 5.8%. The kinetic parameters for sulfate removal were 0.22 ± 0.04 h(-1) with Fe, 0.26 ± 0.04 h(-1) with Fe and Zn and 0.44 ± 0.04 h(-1) with Fe, Zn, and Cu.

Zirconium-based metal organic frameworks loaded on polyurethane foam membrane for simultaneous removal of dyes with different charges.

PubMed

Li, Juan; Gong, Ji-Lai; Zeng, Guang-Ming; Zhang, Peng; Song, Biao; Cao, Wei-Cheng; Liu, Hong-Yu; Huan, Shuang-Yan

2018-10-01

Treating dye wastewater by membrane filtration technology has received much attention from researchers all over the world, however, current studies mainly focused on the removal of singly charged dyes but actual wastewater usually contains dyes with different charges. In this study, the removal of neutral, cationic and anionic dyes in binary or ternary systems was conducted by using zirconium-based metal organic frameworks loaded on polyurethane foam (Zr-MOFs-PUF) membrane. The Zr-MOFs-PUF membrane was fabricated by an in-situ hydrothermal synthesis approach and a hot-pressing process. Neutrally charged Rhodamine B (RB), positively charged Methylene blue (MB), and negatively charged Congo red (CR) were chosen as model pollutants for investigating filtration performance of the membrane. The results of filtration experiments showed that the Zr-MOFs-PUF membrane could simultaneously remove RB, MB, and CR not only from their binary system including RB/MB, RB/CR, and MB/CR mixtures, but also from RB/MB/CR ternary system. The removal of dyes by Zr-MOFs-PUF membrane was mainly attributed to the electrostatic interactions, hydrogen bond interaction, and Lewis acid-base interactions between the membrane and dye molecules. The maximum removal efficiencies by Zr-MOFs-PUF membrane were 98.80% for RB at pH ≈ 7, 97.57% for MB at pH ≈ 9, and 87.39% for CR at pH ≈ 3. Additionally, when the NaCl concentration reached 0.5 mol/L in single dye solutions, the removal efficiencies of RB, MB, and CR by Zr-MOFs-PUF membrane were 93.08%, 79.52%, and 97.82%, respectively. All the results suggested that the as-prepared Zr-MOFs-PUF membrane has great potential in practical treatment of dye wastewater. Copyright © 2018 Elsevier Inc. All rights reserved.

Ultrasonic Remove of Particle Aggregation in Carbon Based Counter Electrodes for Dye-Sensitized Solar Cells.

PubMed

Yang, Pan; Hu, Zi-Jun; Lin, Hong; Lai, Xin-Chun; Zhao, Xiao-Chong; Yang, Li-Jun

2018-06-01

Low-cost carbon materials (carbon black and graphite power) were applied as substitution of platinum (Pt) in counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Three fabrication methods, such as ball-milled, pulp-refined, and ultrasonic-crushed, were applied to remove the particle aggregation in the carbon pastes. Then the carbon based pastes were printed on fluorine-doped transparent conducting oxide (FTO) glasses, used as the CEs for DSSCs. Under illumination of 100 mW/cm2, DSSCs with ultrasonic-crushed CEs (U-CEs) show an energy conversion efficiency of 3.57%, which reach to 65.38% of that with conventional sputtered platinum CEs (5.46%). In addition, U-CEs exhibit a higher catalytic activity and a faster charge transfer rate toward the reduction of I-3 to I-.

Catalytic decolorization of azo-stuff with electro-coagulation method assisted by cobalt phosphomolybdate modified kaolin.

PubMed

Zhuo, Qiongfang; Ma, Hongzhu; Wang, Bo; Gu, Lin

2007-04-02

The new catalytic decoloration of C.I. Acid Red 3R with electro-coagulation (EC) method assisted by cobalt phosphomolybdate modified kaolin has been studied. The result showed that this process could effectively remove the C.I. Acid Red 3R contained in wastewater and its color removal efficiency could reach up to 98.3% in 7 min. The kinetics of the catalytic decolorization of Acid Red 3R was also studied. The decolorization reaction order was dependent on the initial concentration [R](0) with respect to the concentration of C.I. Acid Red 3R. At lower [R](0) the order was first, which then decreases with increasing [R](0). The operating parameters such as initial pH, current density and temperature were also investigated. A possible reaction mechanism was proposed.

Treatment of aging oily wastewater by demulsification/flocculation.

PubMed

Yang, Jing Y; Yan, Liang; Li, Shao P; Xu, Xin R

2016-08-23

The aging oily wastewater (AOW) from Tarim oilfield in China was treated by demulsification/flocculation. A novel sewage treatment agent (YL-7) was developed using a cationic surfactant (LY) and flocculants (polydimethyl diallyl ammonium chloride (PDMDAAC)/polyaluminum chloride (PAC)). At an YL-7 dosage of 320 mg L(-1) at 323 K for 90 min, the oil content of AOW was reduced from 728.8 mg L(-1) to 23.7 mg L(-1), and oil removal efficiency reached 96.7%. Microorganism flocs (extracted from AOW) with high negative zeta potential enhanced the stability of oil/water emulsion. LY and PDMDAAC neutralized the negative charge on the oil droplet surface. PDMDAAC and PAC mainly bridged and swept flocs during the flocculation process. YL-7 was found to be a suitable sewage treatment agent in removing oil from AOW.

Comparison of the MBBR denitrification carriers for advanced nitrogen removal of wastewater treatment plant effluent.

PubMed

Yuan, Quan; Wang, Haiyan; Hang, Qianyu; Deng, Yangfan; Liu, Kai; Li, Chunmei; Zheng, Shengzhi

2015-09-01

The moving bed biofilm reactors (MBBRs) were used to remove the residual NO3(-)-N of wastewater treatment plant (WWTP) effluent, and the MBBR carriers for denitrification were compared. The results showed that high denitrification efficiency can be achieved with polyethylene, polypropylene, polyurethane foam, and haydite carriers under following conditions: 7.2 to 8.0 pH, 24 to 26 °C temperature, 12 h hydraulic retention time (HRT), and 25.5 mg L(-1) external methanol dosage, while the WWTP effluent total nitrogen (TN) was between 2.6 and 15.4 mg L(-1) and NO3(-)-N was between 0.2 and 12.6 mg L(-1). The MBBR filled with polyethylene carriers had higher TN and NO3(-)-N removal rate (44.9 ± 19.1 and 83.4 ± 13.0%, respectively) than those with other carriers. The minimum effluent TN and NO3(-)-N of polyethylene MBBR were 1.6 and 0.1 mg L(-1), respectively, and the maximum denitrification rate reached 23.0 g m(-2) day(-1). When chemical oxygen demand (COD)/TN ratio dropped from 6 to 4, the NO3(-)- N and TN removal efficiency decreased significantly in all reactors except for that filled with polyethylene, which indicated that the polyethylene MBBR can resist influent fluctuation much better. The three-dimensional excitation-emission matrix analysis showed that all the influent and effluent of MBBRs contain soluble microbial products (SMPs)-like organics and biochemical oxygen demand (BOD), which can be removed better by MBBRs filled with haydite and polyethylene carriers. The nitrous oxide reductase (nosZ)-based terminal restriction fragment length polymorphism (T-RFLP) analysis suggested that the dominant bacteria in polyethylene MBBR are the key denitrificans.

Magnetic zeolite NaA: synthesis, characterization based on metakaolin and its application for the removal of Cu2+, Pb2+.

PubMed

Liu, Haibo; Peng, Shuchuan; Shu, Lin; Chen, Tianhu; Bao, Teng; Frost, Ray L

2013-06-01

The optimum parameters for synthesis of zeolite NaA based on metakaolin were investigated according to results of cation exchange capacity and static water adsorption of all synthesis products and selected X-ray diffraction (XRD). Magnetic zeolite NaA was synthesized by adding Fe3O4 in the precursor of zeolite. Zeolite NaA and magnetic zeolite NaA were characterized with scanning electron microscopy (SEM) and XRD. Magnetic zeolite NaA with different Fe3O4 loadings was prepared and used for removal of heavy metals (Cu(2+), Pb(2+)). The results show the optimum parameters for synthesis zeolite NaA are SiO2/Al2O3=2.3, Na2O/SiO2=1.4, H2O/Na2O=50, crystallization time 8h, crystallization temperature 95 °C. The addition of Fe3O4 makes the NaA zeolite with good magnetic susceptibility and good magnetic stability regardless of the Fe3O4 loading, confirming the considerable separation efficiency. Additionally, Fe3O4 loading had a little effect on removal of heavy metal by magnetic zeolite, however, the adsorption capacity still reaches 2.3 mmol g(-1) for Cu(2+), Pb(2+) with a removal efficiency of over 95% in spite of 4.7% Fe3O4 loading. This indicates magnetic zeolite can be used to remove metal heavy at least Cu(2+), Pb(2+) from water with metallic contaminants and can be separated easily after a magnetic process. Copyright © 2013 Elsevier Ltd. All rights reserved.

FeOOH-loaded MnO2 nano-composite: An efficient emergency material for thallium pollution incident.

PubMed

Chen, Meiqing; Wu, Pingxiao; Yu, Langfeng; Liu, Shuai; Ruan, Bo; Hu, Haihui; Zhu, Nengwu; Lin, Zhang

2017-05-01

A FeOOH-loaded MnO 2 nano-composite was developed as an emergency material for Tl(I) pollution incident. Structural characterizations showed that FeOOH successfully loaded onto MnO 2 , the nanosheet-flower structure and high surface area (191 m 2  g -1 ) of material contributed to the excellent performance for Tl(I) removal. FeOOH-loaded MnO 2 with a Fe/Mn molar ratio of 1:2 exhibited a noticeable enhanced capacity for Tl(I) removal compared to that of pure MnO 2 . The outstanding performance for Tl(I) removal involves in extremely high efficiency (achieved equilibrium and drinking water standard within 4 min) and the large maximum adsorption capacity (450 mg g -1 ). Both the control-experiment and XPS characterization proved that the removal mechanism of Tl(I) on FeOOH-loaded MnO 2 included adsorption and oxidation: the oxidation of MnO 2 played an important role for Tl(I) removal, and the adsorption of FeOOH loaded on MnO 2 enhanced Tl(I) purification at the same time. In-depth purification of Tl(I) had reach drinking water standards (0.1 μg L -1 ) at pH above 7, and there wasn't security risk produced from the dissolution of Mn 2+ and Fe 2+ . Moreover, the as-prepared material could be utilized as a recyclable adsorbent regenerated by using NaOH-NaClO binary solution. Therefore, the synthesized FeOOH-loaded MnO 2 in this study has the potential to be applied as an emergency material for thallium pollution incident. Copyright © 2017 Elsevier Ltd. All rights reserved.

Auto-aggregation properties of a novel aerobic denitrifier Enterobacter sp. strain FL.

PubMed

Wang, Xia; An, Qiang; Zhao, Bin; Guo, Jin Song; Huang, Yuan Sheng; Tian, Meng

2018-02-01

Enterobacter sp. strain FL was newly isolated from activated sludge and exhibited significant capability of auto-aggregation as well as aerobic denitrification. The removal efficiencies of NO 3 - -N, total nitrogen (TN), and TOC by strain FL in batch culture reached 94.6, 63.9, and 72.5% in 24 h, respectively. The production of N 2 O and N 2 in the presence of oxygen demonstrated the occurrence of aerobic denitrification. The auto-aggregation index of strain FL reached 54.3%, suggesting a high tendency that the cells would agglomerate into aggregates. The production of extracellular polymeric substances (EPSs), which were mainly composed of proteins followed by polysaccharides, was considered to be related to the cell aggregation according to Fourier transform infrared (FT-IR) and confocal laser scanning microscopy (CLSM). The proteins in EPS were evenly and tightly combined to cells and altered the protein secondary structures of cell surface from random coils to β-sheets and three-turn helices. The alteration of protein secondary structures of cell surface caused by the proteins in EPS might play a dominant role in the auto-aggregation of strain FL. To further assess the feasibility of strain FL for synthetic wastewater treatment, a sequencing batch reactor (SBR), solely inoculated with strain FL, was conducted. During the 16 running cycles, the removal efficiency of NO 3 - -N was 90.2-99.7% and the auto-aggregation index was stabilized at 35.0-41.5%. The EPS promoted the biomass of strain FL to aggregate in the SBR.

Highly integrated hybrid process with ceramic ultrafiltration-membrane for advanced treatment of drinking water: a pilot study.

PubMed

Guo, Jianning; Wang, Lingyun; Zhu, Jia; Zhang, Jianguo; Sheng, Deyang; Zhang, Xihui

2013-01-01

This article presents a highly integrated hybrid process for the advanced treatment of drinking water in dealing with the micro-polluted raw water. A flat sheet ceramic membrane with the pore size of 50∼60 nm for ultrafiltration (UF) is used to integrate coagulation and ozonation together. At the same time, biological activated carbon filtration (BAC) is used to remove the ammonia and organic pollutants in raw water. A pilot study in the scale of 120 m(3)/d has been conducted in Southern China. The mainly-analyzed parameters include turbidity, particle counts, ammonia, total organic carbon (TOC), UV254, biological dissolved organic carbon (BDOC), dissolved oxygen (DO) as well as trans-membrane pressure (TMP). The experiments demonstrated that ceramic UF-membrane was able to remove most of turbidity and suspended particulate matters. The final effluent turbidity reached to 0.14 NTU on average. BAC was effective in removing ammonia and organic matters. Dissolved oxygen (DO) is necessary for the biodegradation of ammonia at high concentration. The removal efficiencies reached to 90% for ammonia with the initial concentration of 3.6 mg/L and 76% for TOC with the initial concentration of 3.8 mg/L. Ozonation can alter the molecular structure of organics in terms of UV254, reduce membrane fouling, and extend the operation circle. It is believed the hybrid treatment process developed in this article can achieve high performance with less land occupation and lower cost compared with the conventional processes. It is especially suitable for the developing countries in order to obtain high-quality drinking water in a cost-effective way.

Geomorphic Response to Two Lowhead Dam Removals in a Mid-Sized Urban River System, Columbus, Ohio, USA: Export of Impounded Reservoir Sediments Results in Upstream Coarsening and Moderate Increases in Downstream Bathymetric Heterogeneity

NASA Astrophysics Data System (ADS)

Comes, E.; Jaeger, K. L.

2016-12-01

Lowhead dams have had a profound cumulative impact on rivers and streams. Their removal is an increasingly popular restoration method, however, geomorphic response remains poorly resolved. This study quantified geomorphic change following two lowhead dam removal in the Olentangy River and the downstream Scioto River, which flows through Columbus, Ohio. A paired control-treatment design compared change above and below a removed dam (treatment) to an existing dam (control) in each river system over a two and three-year period. Upstream treatment reaches included passive and active restoration via in-channel engineering. Channel change was quantified through repeat bathymetric surveys using an acoustic Doppler current profiles and near-surface riverbed substrate sampling at several time periods ( 2 surveys/year). Differencing of digital elevation models from each bathymetric survey quantified changes in erosion and deposition patterns and bathymetric heterogeneity. Results indicate upstream treatment reaches were net erosional with overall substrate coarsening that included D84 sand to gravel clast size shifts. The Olentangy River's downstream treatment reach experienced concurrent erosion and deposition within a given survey although net erosion dominated the first year of the three-year study period. The downstream treatment reach also experienced substantial grain size fluctuation between surveys with little overall change. Unanticipated engineering activities in the downstream treatment reach of the Scioto River confounded geomorphic change in this reach. Non-metric multidimensional scaling analysis indicates a moderate, but abrupt change towards overall increased heterogeneity in the first year following dam removal in the downstream reach with little overall change in the following two years. Active restoration activities in the upstream treatment reach resulted in abrupt, but slight shifts towards decreased bathymetric heterogeneity despite substantial riverbed regrading to create pool-riffle features. Repeat intra-annual surveys revealed that the river system experiences clear seasonal patterns of erosion and deposition with associated substrate coarsening and fining that would not be evident in typical dam removal studies that generally are limited to annual surveys.

Biotreatment of zinc-containing wastewater in a sulfidogenic CSTR: Performance and artificial neural network (ANN) modelling studies.

PubMed

Sahinkaya, Erkan

2009-05-15

Sulfidogenic treatment of sulfate (2-10g/L) and zinc (65-677mg/L) containing simulated wastewater was studied in a mesophilic (35 degrees C) CSTR. Ethanol was supplemented (COD/sulfate=0.67) as carbon and energy source for sulfate-reducing bacteria (SRB). The robustness of the system was studied by increasing Zn, COD and sulfate loadings. Sulfate removal efficiency, which was 70% at 2g/L feed sulfate concentration, steadily decreased with increasing feed sulfate concentration and reached 40% at 10g/L. Over 99% Zn removal was attained due to the formation of zinc-sulfide precipitate. COD removal efficiency at 2g/L feed sulfate concentration was over 94%, whereas, it steadily decreased due to the accumulation of acetate at higher loadings. Alkalinity produced from acetate oxidation increased wastewater pH remarkably when feed sulfate concentration was 5g/L or lower. Electron flow from carbon oxidation to sulfate reduction averaged 83+/-13%. The rest of the electrons were most likely coupled with fermentative reactions as the amount of methane production was insignificant. The developed ANN model was very successful as an excellent to reasonable match was obtained between the measured and the predicted concentrations of sulfate (R=0.998), COD (R=0.993), acetate (R=0.976) and zinc (R=0.827) in the CSTR effluent.

Ethylenediamine-N,N′-Disuccinic Acid (EDDS)—Enhanced Flushing Optimization for Contaminated Agricultural Soil Remediation and Assessment of Prospective Cu and Zn Transport

PubMed Central

Ferraro, Alberto; Fabbricino, Massimiliano; La Marca, Agostino; Panico, Antonio; Spasiano, Danilo; Tognacchini, Alice; Pirozzi, Francesco

2018-01-01

This paper presents the results of an experimental study aimed at investigating the effect of operative parameters on the efficiency of a soil flushing process, conducted on real contaminated soil containing high amounts of Cu and Zn. Soil flushing tests were carried out with Ethylenediamine-N,N′-disuccinic acid (EDDS) as a flushing agent due to its high biodegradability and environmentally friendly characteristics. Process parameters such as Empty-Bed Contact Time (EBCT) and EDDS solution molarity were varied from 21–33 h and from 0.36–3.6 mM, respectively. Effects on the mobility of cations such as Fe and Mn were also investigated. Results showed that very high performances can be obtained at [EDDS] = 3.6 mM and EBCT = 33 h. In these conditions, in fact, the amount of removed Cu was 53%, and the amount of removed Zn was 46%. Metal distribution at different depths from the top surface revealed that Cu has higher mobility than Zn. The process results were strongly dependent on the exchange of metals due to the different stability constants of the EDDS complexes. Finally, results from a comparative study showed that soil washing treatment reached the same removal efficiency of the flushing process in a shorter time but required a larger amount of the EDDS solution. PMID:29562649

Facile fabrication of carbon brush with reduced graphene oxide (rGO) for decreasing resistance and accelerating pollutants removal in bio-electrochemical systems.

PubMed

Cui, Dan; Yang, Li-Ming; Liu, Wen-Zong; Cui, Min-Hua; Cai, Wei-Wei; Wang, Ai-Jie

2018-07-15

Low electrode resistance is crucial for achieving efficient reactions in bio-electrochemical system (BES), especially considering the factors of BES scaling-up and microbial effects. Graphene has revealed a cornucopia of potential applications due to its high conductivity and extraordinary electrochemical properties. Here, significant reduction of electrode resistance and increment of electrochemical activity were achieved by fabricating the three-dimensional carbon brush using reduced graphene oxide (rGO/carbon brush) through one-step electro-deposition without any binder. The rGO/carbon brush was employed as cathode in BES equipped with bio-anode for azo compound (AO7) removal. The charge transfer resistances of cathode part and whole cell were decreased by 89% and 65%, respectively. The reactor showed quickly start-up within 48 h with peak cycle current six fold increase relative to the control. AO7 decolorization efficiency reached 91.1 ± 0.1% at 4 h and 97.6 ± 0.4% at 6 h. Effective decolorization of AO7 was at rate up to 650.7 g AO7/m 3 ·h. The results indicated that the advantages of graphene and three-dimensional carbon brush successfully improved the overall performance of BES and enhanced refractory pollutants removal when applied to specific wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Ethylenediamine-N,N'-Disuccinic Acid (EDDS)-Enhanced Flushing Optimization for Contaminated Agricultural Soil Remediation and Assessment of Prospective Cu and Zn Transport.

PubMed

Race, Marco; Ferraro, Alberto; Fabbricino, Massimiliano; La Marca, Agostino; Panico, Antonio; Spasiano, Danilo; Tognacchini, Alice; Pirozzi, Francesco

2018-03-18

This paper presents the results of an experimental study aimed at investigating the effect of operative parameters on the efficiency of a soil flushing process, conducted on real contaminated soil containing high amounts of Cu and Zn. Soil flushing tests were carried out with Ethylenediamine- N , N '-disuccinic acid (EDDS) as a flushing agent due to its high biodegradability and environmentally friendly characteristics. Process parameters such as Empty-Bed Contact Time (EBCT) and EDDS solution molarity were varied from 21-33 h and from 0.36-3.6 mM, respectively. Effects on the mobility of cations such as Fe and Mn were also investigated. Results showed that very high performances can be obtained at [EDDS] = 3.6 mM and EBCT = 33 h. In these conditions, in fact, the amount of removed Cu was 53%, and the amount of removed Zn was 46%. Metal distribution at different depths from the top surface revealed that Cu has higher mobility than Zn. The process results were strongly dependent on the exchange of metals due to the different stability constants of the EDDS complexes. Finally, results from a comparative study showed that soil washing treatment reached the same removal efficiency of the flushing process in a shorter time but required a larger amount of the EDDS solution.

Determination of the promoter region of mouse ribosomal RNA gene by an in vitro transcription system.

PubMed Central

Yamamoto, O; Takakusa, N; Mishima, Y; Kominami, R; Muramatsu, M

1984-01-01

Sequences required for a faithful and efficient transcription of a cloned mouse ribosomal RNA gene (rDNA) are determined by testing a series of deletion mutants in an in vitro transcription system utilizing two kinds of mouse cellular extract. Deletion of sequences upstream of -40 or downstream of +52 causes only slight reduction in promoter activity as compared with the "wild-type" template. For upstream deletion mutants, the removal of a sequence between -40 and -35 causes a significant decrease in the capacity to direct efficient initiation. This decrease becomes more pronounced when the deletion reaches -32 and the sequence A-T-C-T-T-T, conserved among mouse, rat, and human rDNAs, is lost. Residual template activity is further reduced as more upstream sequence is deleted and finally becomes undetectable when the deletion is extended from -22 down to -17, corresponding to the loss of the conserved sequence T-A-T-T-G. As for downstream deletion mutants, the removal of the sequence downstream of +23 causes some (and further deletions up to +11 cause a more) serious decrease in template activity in vitro. These deletions involve other conserved sequences downstream of the transcription start site. However, the removal of the original transcription start site does not abolish the transcription initiation completely, provided that the whole upstream sequence is intact. Images PMID:6320178

Removal of Cr(VI) by surfactant modified Auricularia auricula spent substrate: biosorption condition and mechanism.

PubMed

Dong, Liying; Jin, Yu; Song, Tao; Liang, Jinsong; Bai, Xin; Yu, Sumei; Teng, Chunying; Wang, Xin; Qu, Juanjuan; Huang, Xiaomei

2017-07-01

Auricularia auricula spent substrate (AASS) modified by didodecyldimethylammonium bromide(DDAB) was used as adsorbent to remove Cr(VI) from aqueous solution. Based on a single-factor experiment and response surface methodology, the optimal conditions were adsorbent dosage of 1.5 g/L, pH value of 4.0, initial Cr(VI) concentration of 19 mg/L, temperature of 25 °C, biosorption time of 120 min, rotational speed of 150 r/min, respectively, under which biosorption capacity could reach 12.16 mg/g compared with unmodified AASS (6.058 mg/g). DDAB modification could enlarge the specific surface area and porous diameter of the adsorbents, and supply hydrophilic and hydrophobic groups capable of adsorbing at the interfaces. In addition, DDAB increased ionic exchange and complex formation demonstrated by variations of elemental contents, shifts of carboxyl, amine groups, hydroxyl, alkyl chains, and phosphate groups as well as the crystal structure of the Cr-O compounds. Variations of peaks and energy in XPS analysis also testified the reduction of Cr(VI) to Cr(III).The biosorption behavior of modified AASS was in line with Langmuir and Freundlich isotherm equation. The final regeneration efficiency was 62.33% after three biosorption-desorption cycles. Apparently, DDBA is a eximious modifier and DDBA-modified AASS was very efficient for Cr(VI) removal.

Ammonia removal in electrochemical oxidation: mechanism and pseudo-kinetics.

PubMed

Li, Liang; Liu, Yan

2009-01-30

This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO(2)/Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode-liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl(-). The oxidation rates of ammonia ranged from 1.0 to 12.3 mg N L(-1)h(-1) and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl(-). About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N(2) in the produced gas. The rate at which Cl(-) lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl(-) concentration affected the constant of the pseudo zero-order kinetics, expressed by k=0.0024[Cl(-)]xj. The ammonia was reduced to less than 0.5 mg N L(-1) after 2h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements.

Removal and retention of phosphorus by periphyton from wastewater with high organic load.

PubMed

Cao, Jinxiang; Hong, Xiaoxing; Pei, Guofeng

2014-01-01

The total phosphorus (TP) removal efficiency from organic wastewater (pig farm and distillery wastewater) were estimated by using filamentous green algae (FGA) and benthic algal mats (BAM) treatment systems under laboratory conditions, and the contents of periphyton phosphorus fractions were determined by using a sequential extraction. The removal rates of TP reached 59-78% within the first 8 days of all treatment systems and could achieve average 80% during 30 day period, and the phosphorus removal rates by using BAM was higher than that of FGA. The ability of retention TP of periphyton enhanced gradually, the BAM TP contents were higher than that of FGA, the highest TP concentrations of BAM and FGA were 26.24 and 10.52 mg P g(-1)·dry weight. Inorganic phosphorus (IP) always exceeded 67.5% of TP, but the organic phosphorus fraction only made up less than 20% of TP. The calcium-binding phosphorus (Ca-P) was the dominant fraction and its relative contribution to TP was more than 40%. The TP was also strongly and positively correlated with the IP and Ca-P (p < 0.01) in periphyton. It showed that the periphyton had a potential ability of rapid phosphorus removing and remarkable retention from wastewater with high load phosphorus.

Effective removal of hazardous trace metals from recovery boiler fly ashes.

PubMed

Kinnarinen, Teemu; Golmaei, Mohammad; Jernström, Eeva; Häkkinen, Antti

2018-02-15

The objective of this study is to introduce a treatment sequence enabling straightforward and effective recovery of hazardous trace elements from recovery boiler fly ash (RBFA) by a novel method, and to demonstrate the subsequent removal of Cl and K with the existing crystallization technology. The treatment sequence comprises two stages: dissolution of most other RBFA components than the hazardous trace elements in water in Step 1 of the treatment, and crystallization of the process chemicals in Step 2. Solid-liquid separation has an important role in the treatment, due to the need to separate first the small solid residue containing the trace elements, and to separate the valuable crystals, containing Na and S, from the liquid rich in Cl and K. According to the results, nearly complete recovery of cadmium, lead and zinc can be reached even without pH adjustment. Some other metals, such as Mg and Mn, are removed together with the hazardous metals. Regarding the removal of Cl and K from the process, in this non-optimized case the removal efficiency was satisfactory: 60-70% for K when 80% of sodium was recovered, and close to 70% for Cl when 80% of sulfate was recovered. Copyright © 2017 Elsevier B.V. All rights reserved.

Remediation of Urban River Water by Pontederia Cordata Combined with Artificial Aeration: Organic Matter and Nutrients Removal and Root-Adhered Bacterial Communities.

PubMed

Gu, Dungang; Xu, Huan; He, Yan; Zhao, Feng; Huang, Minsheng

2015-01-01

Macrophyte combined with artificial aeration is a promising in situ remediation approach for urban rivers polluted with nutrients and organic matter. However, seasonal variations and aeration effects on phytoremediation performance and root-adhered microbial communities are still unclear. In this study, Pontederia cordata was used to treat polluted urban river water under various aeration intensities. Results showed that the highest removal efficiencies of chemical oxygen demand (COD(Cr)) and total nitrogen (TN) were attained under aeration of 30 L min(-1) in spring and summer and 15 L min(-1) in autumn, while total phosphorus (TP) removal reached maximum with aeration of 15 L min(-1) in all seasons. Moderate aeration was beneficial for increasing the diversity of root-adhered bacteria communities, and the shift of bacterial community structure was more pronounced in spring and autumn with varying aeration intensity. The dual effect, i.e. turbulence and dissolved oxygen (DO), of aeration on the removal of COD(Cr) and TN prevailed over the individual effect of DO, while DO was the most influential factor for TP removal and the root-adhered bacterial community diversity. P. cordata combined with 15 L min(-1) aeration was deemed to be the best condition tested in this study.

Sustainable nitrogen removal by denitrifying anammox applied for anaerobic pre-treated potato wastewater.

PubMed

Mulder, A; Versprille, A I; van Braak, D

2012-01-01

The feasibility of sustainable nitrogen removal was investigated in a two stage biofilm configuration consisting of a MBBR (Moving Bed Biofilm Reactor) and a Deamox reactor (Biobed-EGSB). The MBBR is used for nitrification and the denitrifying ammonium oxidation (Deamox) is aimed at a nitrogen removal process in which part of the required nitrite for the typical anammox reaction originated from nitrate. Anaerobic pre-treated potato wastewater was supplied to a MBBR and Deamox reactor operated in series with a bypass flow of 30%. The MBBR showed stable nitrite production at ammonium-loading rates of 0.9-1.0 kg NH₄-N/m³ d with ammonium conversion rates of 0.80-0.85 kg NH₄-N/m³ d. The nitrogen-loading rate and conversion rate of the Deamox reactor were 1.6-1.8 and 1.6 kg N/m³ d. The maximum ammonium removal capacity in the Deamox reactor was 0.6 kg NH₄-N/m³ d. The removal efficiency of soluble total nitrogen reached 90%. The Deamox process performance was found to be negatively affected during decline of the operating temperature from 33 to 22 °C and by organic loading rates with a chemical oxygen demand (COD)/NO₂-N ratio >1.

A selective molecularly imprinted polymer for immobilization of acetylcholinesterase (AChE): an active enzyme targeted and efficient method.

PubMed

Demirci, Gökhan; Doğaç, Yasemin İspirli; Teke, Mustafa

2015-11-01

In the present study, we immobilized acetylcholinesterase (AChE) enzyme onto acetylcholine removed imprinted polymer and acetylcholine containing polymer. First, the polymers were produced with acetylcholine, substrate of AChE, by dispersion polymerization. Then, the enzyme was immobilized onto the polymers by using two different methods: In the first method (method A), acetylcholine was removed from the polymer, and then AChE was immobilized onto this polymer (acetylcholine removed imprinted polymer). In the second method (method B), AChE was immobilized onto acetylcholine containing polymer by affinity. In method A, enzyme-specific species (binding sites) occurred by removing acetylcholine from the polymer. The immobilized AChE reached 240% relative specific activity comparison with free AChE because the active enzyme molecules bounded onto the polymer. Transmission electron microscopy results were taken before and after immobilization of AChE for the assessment of morphological structure of polymer. Also, the experiments, which include optimum temperature (25-65 °C), optimum pH (3-10), thermal stability (4-70 °C), kinetic parameters, operational stability and reusability, were performed to determine the characteristic of the immobilized AChE. Copyright © 2015 John Wiley & Sons, Ltd.

Anaerobic digestion of blackwater from vacuum toilets and kitchen refuse in a continuous stirred tank reactor (CSTR).

PubMed

Wendland, C; Deegener, S; Behrendt, J; Toshev, P; Otterpohl, R

2007-01-01

The objective of this research was mesophilic anaerobic digestion of blackwater from vacuum toilets (BW) and kitchen refuse (KR) in a CSTR within an ecological sanitation system. A detailed investigation of the BW characteristics was carried out. Research on anaerobic digestion was performed with CSTR of 101 volume at HRT of 10, 15 and 20 days. The digestion of BW at 20 days HRT showed stable performance without inhibition effects, in spite of relatively high ammonium concentrations. The removal of total and particulate COD was 61% and 53%, respectively, and the methane yield 10/CH4/cap/day. The addition of kitchen refuse (KR) improved the performance of the CSTR in terms of COD removal efficiency and methane yield. At 20 days HRT the removal of total and particulate COD increased up to 71% and 67%, respectively, and the methane yield to 27/CH4/cap/day. The results at 15 days HRT showed similar performance. At HRT of 10 days, the anaerobic treatment was limited but reached steady state conditions at higher VFA concentrations in the effluent, with a decrease of COD removal of 30 to 33% and of methane yields of 19 to 21%.

Removal efficiency of polycyclic aromatic hydrocarbons and phthalate esters by surface flow wetland in Shunyi district, Beijing

NASA Astrophysics Data System (ADS)

Li, Binghua; Liu, Licai; Han, Li; Yang, Yong

2017-03-01

The surface flow wetland (SFW) system was located on Shunyi district, Beijing. It was built to treat industrial wastewater and domestic sewage, which were looked as its influent. Here sixteen polycyclic aromatic hydrocarbons (PAHs) and six phthalate esters (PAEs) were detected by gas chromatography-mass spectrometry (GC-MS).To determine treatment effect of SFW system, concentrations of targeted compounds in the influent were compared with those in the effluent. Results showed typical compounds of industrial wastewater were naphthalene (NAP), phenanthrene (PHE), dibutyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP), and their concentrations were ranged from 122.6 ng.L-1 to 760.6 ng.L-1. However typical compounds of domestic sewage were NAP, anthracene (ANT), PHE, DBP, diethyl phthalate (DEP), DEHP, and their concentrations were ranged from 280 ng.L-1 to 7998.1 ng.L-1. Typical compounds of effluent were NAP, PHE, DBP, DEHP, and their concentrations changed between 4.2 ng.L-1 and 1430.74 ng.L-1. The removal rate of those compounds were 10% ~ 99%, and nineteen compounds removal rate reached above 70%.Therefore, it can be concluded that SFW system had a strong effect on the removal of these compounds.

The promise of a specially-designed graft copolymer of acrylic acid onto cellulose as selective sorbent for heavy metal ions.

PubMed

Essawy, Hisham A; Mohamed, Magdy F; Ammar, Nabila S; Ibrahim, Hanan S

2017-10-01

A specially-designed graft copolymer of acrylic acid onto in-situ formed cellulose-fulvate hybrid showed privileged tendency for uptake of Pb(II) during competitive removal from a mixture containing Cd(II) and Ni(II) within 5min at pH 5. This novel trend is attributed mainly to the crowded high content of coordinating centers within the designed graft copolymer along with the acquired superabsorbency. This provides an outstanding tool to separate some metal ions selectively from mixtures containing multiple ions on kinetic basis. Thus, the designed graft copolymer structure exhibited superior efficiency that reached ∼95% for sole removal of Pb(II). Kinetic modeling for Pb(II) individual removal showed excellent fitting with a pseudo second-order model. Intraparticle diffusion model on the other hand ensured governance of boundary layer effect over diffusion during the removal process due to the superabsorbency feature of the graft copolymer. The experimental findings were described with models such as Freundlich, Langmuir, and Dubinin-Radushkevich. The Langmuir and Freundlich models showed convenience with the adsorption isotherm of Pb(II) onto the developed graft copolymer. Copyright © 2017 Elsevier B.V. All rights reserved.

Sequential application of chelating agents and innovative surfactants for the enhanced electroremediation of real sediments from toxic metals and PAHs.

PubMed

Hahladakis, John N; Lekkas, Nikolaos; Smponias, Andreas; Gidarakos, Evangelos

2014-06-01

This study focused on the sequential application of a chelating agent (citric acid) followed by a surfactant in the simultaneous electroremediation of real contaminated sediments from toxic metals and Polycyclic Aromatic Hydrocarbons (PAHs). Furthermore, the efficiency evaluation of two innovative non-ionic surfactants, commercially known as Poloxamer 407 and Nonidet P40, was investigated. The results indicated a removal efficacy of approximately 43% and 48% for the summation of PAHs (SUM PAHs), respectively for the aforementioned surfactants, much better than the one obtained by the use of Tween 80 (nearly 21%). Individual PAHs (e.g. fluorene) were removed in percentages that reached almost 84% and 92% in the respective electrokinetic experiments when these new surfactants were introduced. In addition, the combined-enhanced sequential electrokinetic treatment with citric acid improved dramatically the removal of Zn and As, compared to the unenhanced run, but did not favor the other toxic metals examined. Since no improvement in metal removal percentages occurred when Tween 80 was used, significant contribution to this matter should also be attributed to the solubilization capacity of these innovative, in electrokinetic remediation, non-ionic surfactants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Adsorptive removal of selected pharmaceuticals by mesoporous silica SBA-15.

PubMed

Bui, Tung Xuan; Choi, Heechul

2009-09-15

The removal of five selected pharmaceuticals, viz., carbamazepine, clofibric acid, diclofenac, ibuprofen, and ketoprofen was examined by batch sorption experiments onto a synthesized mesoporous silica SBA-15. SBA-15 was synthesized and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption-desorption measurement, and point of zero charge (PZC) measurement. Pharmaceutical adsorption kinetics was rapid and occurred on a scale of minutes, following a pseudo-second-order rate expression. Adsorption isotherms were best fitted by the Freundlich isotherm model. High removal rates of individual pharmaceuticals were achieved in acidic media (pH 3-5) and reached 85.2% for carbamazepine, 88.3% for diclofenac, 93.0% for ibuprofen, 94.3% for ketoprofen, and 49.0% for clofibric acid at pH 3 but decreased with increase in pH. SBA-15 also showed high efficiency for removal of a mixture of 5 pharmaceuticals. Except for clofibric acid (35.6%), the removal of pharmaceuticals in the mixture ranged from 75.2 to 89.3%. Based on adsorption and desorption results, the mechanism of the selected pharmaceuticals was found to be a hydrophilic interaction, providing valuable information for further studies to design materials for the purpose. The results of this study suggest that mesoporous-silica-based materials are promising adsorbents for removing pharmaceuticals from not only surface water but also wastewater of pharmaceutical industrial manufactures.

An empirical model for parameters affecting energy consumption in boron removal from boron-containing wastewaters by electrocoagulation.

PubMed

Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar

2007-06-01

In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0 mA/cm(2), initial boron concentration 100mg/L and solution temperature 293 K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following; [formula in text]. Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.

Removal of dissolved organic matter in municipal effluent with ozonation, slow sand filtration and nanofiltration as high quality pre-treatment option for artificial groundwater recharge.

PubMed

Linlin, Wu; Xuan, Zhao; Meng, Zhang

2011-04-01

In the paper the combination process of ozonation, slow sand filtration (SSF) and nanofiltration (NF) was investigated with respect to dissolved organic matter (DOM) removal as high quality pre-treatment option for artificial groundwater recharge. With the help of ozonation leading to breakdown of the large organic molecules, SSF preferentially removes soluble microbial by-product-like substances and DOM with molecular weight (MW) less than 1.0 kDa. NF, however, removes aromatic, humic acid-like and fulvic acid-like substances efficiently and specially removes DOM with MW above 1.0 kDa. The residual DOM of the membrane permeate is dominated by small organics with MW 500 Da, which can be further reduced by the aquifer treatment, despite of the very low concentration. Consequently, the O(3)/SSF/NF system offers a complementary process in DOM removal. Dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP) can be reduced from 6.5±1.1 to 0.7±0.3 mg L(-1) and from 267±24 to 52±6 μg L(-1), respectively. The very low DOC concentration of 0.6±0.2 mg L(-1) and THMFP of 44±4 μg L(-1) can be reached after the aquifer treatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Performance and microbial community of anammox in presence of micro-molecule carbon source.

PubMed

He, Shilong; Yang, Wan; Qin, Meng; Mao, Zhen; Niu, Qigui; Han, Ming

2018-08-01

Because ammonium (NH 4 + -N) coexists with organic matter in some wastewaters, the possible adverse influences of organic matter become a major concern in the applications of anaerobic ammonium oxidation (anammox). In this study, the effects of acetate, as a representative of micro-molecule organic matter, on anammox were investigated. Efficient nitrogen removal was realized because denitrifying bacteria and anammox bacteria (AnAOB) had a better synergistic effect under the condition of chemical oxygen demand (COD) concentrations lower than 251 ± 7 mg L -1 . Furthermore, the nitrogen removal efficiency (NRE) decreased to 82.02 ± 3.14% when COD was increased to 730 ± 9 mg L -1 , and effluent free ammonia (FA) reached 21.93 ± 4.71 mg L -1 might be one of factors leading to inhibition. However, the nitrogen-removal contribution rate of anammox remained steady at 61.97 ± 2.84% at COD of 730 ± 9 mg L -1 , which indicated that anammox was still dominant in the system. AnAOB, such as Ca. Kuenenia and Ca. Jettenia, and denitrifying bacteria, such as Denitratisoma and Thauera, were found to coexist in the reactor. Interestingly, Ca. Kuenenia presented in the trend of first decreased then increased with the increasing of organic matter concentration, which might be one of reasons that anammox played an important role in nitrogen removal at high COD concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydraulic effects on nitrogen removal in a tidal spring-fed river

NASA Astrophysics Data System (ADS)

Hensley, Robert T.; Cohen, Matthew J.; Korhnak, Larry V.

2015-03-01

Hydraulic properties such as stage and residence time are important controls on riverine N removal. In most rivers, these hydraulic properties vary with stochastic precipitation forcing, but in tidal rivers, hydraulics variation occurs on a predictable cycle. In Manatee Springs, a highly productive, tidally influenced spring-fed river in Florida, we observed significant reach-scale N removal that varied in response to tidally driven variation in hydraulic properties as well as sunlight-driven variation in assimilatory uptake. After accounting for channel residence time and stage variation, we partitioned the total removal signal into assimilatory (i.e., plant uptake) and dissimilatory (principally denitrification) pathways. Assimilatory uptake was strongly correlated with primary production and ecosystem C:N was concordant with tissue stoichiometry of the dominant autotrophs. The magnitude of N removal was broadly consistent in magnitude with predictions from models (SPARROW and RivR-N). However, contrary to model predictions, the highest removal occurred at the lowest values of τ/d (residence time divided by depth), which occurred at low tide. Removal efficiency also exhibited significant counterclockwise hysteresis with incoming versus outgoing tides. This behavior is best explained by the sequential filling and draining of transient storage zones such that water that has spent the longest time in the storage zone, and thus had the most time for N removal, drains back into the channel at the end of an outgoing tide, concurrent with shortest channel residence times. Capturing this inversion of the expected relationship between channel residence time and N removal highlights the need for nonsteady state reactive transport models.

[Optimization and comparison of nitrogen and phosphorus removal by different aeration modes in oxidation ditch].

PubMed

Guo, Chang-Zi; Peng, Dang-Cong; Cheng, Xue-Mei; Wang, Dan

2012-03-01

The oxidation ditch operation mode was simulated by sequencing batch reactor (SBR) system with alternate stirring and aeration. The nitrogen and phosphorus removal efficiencies were investigated in two different aeration modes: point aeration and step aeration. Experimental results show that oxygen is dissolved more efficiently in point aeration mode with a longer aerobic region in the same air supply capacity, but dissolved oxygen (DO) utilization efficiency for nitrogen and phosphorus removal is high in step aeration mode. Nitrification abilities of the two modes are equal with ammonia-nitrogen (NH4(+) -N) removal efficiency of 96.68% and 97.03%, respectively. Nitrifier activities are 4.65 and 4.66 mg x (g x h)(-1) respectively. When the ratio of anoxic zones and the aerobic zones were 1, the total nitrogen (TN) removal efficiency of point aeration mode in 2, 4 or 7 partitions was respectively 60.14%, 47.93% and 33.7%. The total phosphorus (TP) removal efficiency was respectively 28.96%, 23.75% and 24.31%. The less the partitions, the higher the nitrogen and phosphorus removal efficiencies, but it is in more favor of TN removal. As for step aeration mode with only one partitioning zone, the TN and TP removal efficiencies are respectively 64.21% and 49.09%, which is better than in point aeration mode, but more conducive to the improvement of TP removal efficiency. Under the condition of sufficient nitrification in step aeration mode, the nitrogen and phosphorus removal is better with the increase of anoxic zone. The removal efficiencies of TN and TP respectively rose to 73.94% and 54.18% when the ratio of anoxic zones and the aerobic zones was increased from 1 : 1 to 1. 8 : 1. As the proportion of anoxic zones was enlarged further, nitrification and operation stability were weakened so as to affect the nitrogen and phosphorus removal efficiencies.

Potassium fulvate-modified graft copolymer of acrylic acid onto cellulose as efficient chelating polymeric sorbent.

PubMed

Mohamed, Magdy F; Essawy, Hisham A; Ammar, Nabila S; Ibrahim, Hanan S

2017-01-01

Acrylic acid (AA) was graft copolymerized from cellulose (Cell) in presence of potassium fulvate (KF) in order to enhance the chemical activity of the resulting chelating polymer and the handling as well. Fourier transform infrared (FTIR) proved that KF was efficiently inserted and became a permanent part of the network structure of the sorbent in parallel during the grafting copolymerization. Scanning electron microscopy (SEM) revealed intact homogeneous structure with uniform surface. This indicates improvement of the handling, however, it was not the case for the graft copolymer of acrylic acid onto cellulose in absence of KF, which is known to be brittle and lacks mechanical integrity. Effective insertion of this co-interpenetrating agent provided more functional groups, such as OH and COOH, which improved the chelating power of the produced sorbent as found for the removal of Cu 2+ ions from its aqueous solutions (the removal efficiency reached ∼98.9%). Different models were used to express the experimental data. The results corroborated conformity of the pseudo-second order kinetic model and Langmuir isotherm model to the sorption process, which translates into dominance of the chemisorption. Regeneration of the chelating polymers under harsh conditions did not affect the efficiency of copper ions uptake up to three successive cycles. A thermodynamic investigation ensured exothermic nature of the adsorption process that became less favourable at higher temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser beam machining of polycrystalline diamond for cutting tool manufacturing

NASA Astrophysics Data System (ADS)

Wyszyński, Dominik; Ostrowski, Robert; Zwolak, Marek; Bryk, Witold

2017-10-01

The paper concerns application of DPSS Nd: YAG 532nm pulse laser source for machining of polycrystalline WC based diamond inserts (PCD). The goal of the research was to determine optimal laser cutting parameters for cutting tool shaping. Basic criteria to reach the goal was cutting edge quality (minimalization of finishing operations), material removal rate (time and cost efficiency), choice of laser beam characteristics (polarization, power, focused beam diameter). The research was planned and realised and analysed according to design of experiment rules (DOE). The analysis of the cutting edge was prepared with use of Alicona Infinite Focus measurement system.

Lab-scale investigation on remediation of diesel-contaminated aquifer using microwave energy.

PubMed

Falciglia, Pietro P; Maddalena, Riccardo; Mancuso, Giuseppe; Messina, Valeria; Vagliasindi, Federico G A

2016-02-01

Aquifer contamination with diesel fuel is a worldwide environmental problem, and related available remediation technologies may not be adequately efficient, especially for the simultaneous treatment of both solid and water phases. In this paper, a lab-scale 2.45 GHz microwave (MW) treatment of an artificially diesel-contaminated aquifer was applied to investigate the effects of operating power (160, 350 and 500 W) and time on temperature profiles and contaminant removal from both solid and water phases. Results suggest that in diesel-contaminated aquifer MW remediation, power significantly influences the final reachable temperature and, consequently, contaminant removal kinetics. A maximum temperature of about 120 °C was reached at 500 W. Observed temperature values depended on the simultaneous irradiation of both aquifer grains and groundwater. In this case, solid phase heating is limited by the maximum temperature that interstitial water can reach before evaporation. A minimal residual diesel concentration of about 100 mg kg(-1) or 100 mg L(-1) was achieved by applying a power of 500 W for a time of 60 min for the solid or water phase, respectively. Measured residual TPH fractions showed that MW heating resulted in preferential effects of the removal of different TPH molecular weight fractions and that the evaporation-stripping phenomena plays a major role in final contaminant removal processes. The power low kinetic equation shows an excellent fit (r(2) > 0.993) with the solid phase residual concentration observed for all the powers investigated. A maximum diesel removal of 88 or 80% was observed for the MW treatment of the solid or water phase, respectively, highlighting the possibility to successfully and simultaneously remediate both the aquifer phases. Consequently, MW, compared to other biological or chemical-physical treatments, appears to be a better choice for the fast remediation of diesel-contaminated aquifers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transparent exopolymer particle removal in different drinking water production centers.

PubMed

Van Nevel, Sam; Hennebel, Tom; De Beuf, Kristof; Du Laing, Gijs; Verstraete, Willy; Boon, Nico

2012-07-01

Transparent exopolymer particles (TEP) have recently gained interest in relation to membrane fouling. These sticky, gel-like particles consist of acidic polysaccharides excreted by bacteria and algae. The concentrations, expressed as xanthan gum equivalents L⁻¹ (μg X(eq) L⁻¹), usually reach hundred up to thousands μg X(eq) L⁻¹ in natural waters. However, very few research was performed on the occurrence and fate of TEP in drinking water, this far. This study examined three different drinking water production centers, taking in effluent of a sewage treatment plant (STP), surface water and groundwater, respectively. Each treatment step was evaluated on TEP removal and on 13 other chemical and biological parameters. An assessment on TEP removal efficiency of a diverse range of water treatment methods and on correlations between TEP and other parameters was performed. Significant correlations between particulate TEP (>0.4 μm) and viable cell concentrations were found, as well as between colloidal TEP (0.05-0.4 μm) and total COD, TOC, total cell or viable cell concentrations. TEP concentrations were very dependent on the raw water source; no TEP was detected in groundwater but the STP effluent contained 1572 μg X(eq) L⁻¹ and the surface water 699 μg X(eq) L⁻¹. Over 94% of total TEP in both plants was colloidal TEP, a fraction neglected in nearly every other TEP study. The combination of coagulation and sand filtration was effective to decrease the TEP levels by 67%, while the combination of ultrafiltration and reverse osmosis provided a total TEP removal. Finally, in none of the installations TEP reached the final drinking water distribution system at significant concentrations. Overall, this study described the presence and removal of TEP in drinking water systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

40 CFR 63.9323 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.9323 Section 63.9323 Protection of Environment... determine the add-on control device emission destruction or removal efficiency? You must use the procedures... removal efficiency as part of the performance test required by § 63.9310. You must conduct three test runs...

40 CFR 63.9323 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... device emission destruction or removal efficiency? 63.9323 Section 63.9323 Protection of Environment... determine the add-on control device emission destruction or removal efficiency? You must use the procedures... removal efficiency as part of the performance test required by § 63.9310. You must conduct three test runs...

40 CFR 63.4166 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.4166 Section 63.4166 Protection of Environment....4166 How do I determine the add-on control device emission destruction or removal efficiency? (a) For... device organic emissions destruction or removal efficiency, using Equation 2 of this section. ER23JY02...

40 CFR 63.3966 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... device emission destruction or removal efficiency? 63.3966 Section 63.3966 Protection of Environment... or removal efficiency? You must use the procedures and test methods in this section to determine the add-on control device emission destruction or removal efficiency as part of the performance test...

40 CFR 63.4965 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.4965 Section 63.4965 Protection of Environment....4965 How do I determine the add-on control device emission destruction or removal efficiency? You must... destruction or removal efficiency as part of the performance test required by § 63.4960. You must conduct...

40 CFR 63.3966 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.3966 Section 63.3966 Protection of Environment... or removal efficiency? You must use the procedures and test methods in this section to determine the add-on control device emission destruction or removal efficiency as part of the performance test...

Fine-tuning key parameters of an integrated reactor system for the simultaneous removal of COD, sulfate and ammonium and elemental sulfur reclamation.

PubMed

Yuan, Ye; Chen, Chuan; Liang, Bin; Huang, Cong; Zhao, Youkang; Xu, Xijun; Tan, Wenbo; Zhou, Xu; Gao, Shuang; Sun, Dezhi; Lee, Duujong; Zhou, Jizhong; Wang, Aijie

2014-03-30

In this paper, we proposed an integrated reactor system for simultaneous removal of COD, sulfate and ammonium (integrated C-S-N removal system) and investigated the key parameters of the system for a high level of elemental sulfur (S(0)) production. The system consisted of 4 main units: sulfate reduction and organic carbon removal (SR-CR), autotrophic and heterotrophic denitrifying sulfide removal (A&H-DSR), sulfur reclamation (SR), and aerated filter for aerobic nitrification (AN). In the system, the effects of key operational parameters on production of elemental sulfur were investigated, including hydraulic retention time (HRT) of each unit, sulfide/nitrate (S(2-)-S/NO3(-)-N) ratios, reflux ratios between the A&H-DSR and AN units, and loading rates of chemical oxygen demand (COD), sulfate and ammonium. Physico-chemical characteristics of biosulfur were studied for acquiring efficient S(0) recovery. The experiments successfully explored the optimum parameters for each unit and demonstrated 98% COD, 98% sulfate and 78% nitrogen removal efficiency. The optimum HRTs for SR-CR, A&H-DSR and AN were 12h, 3h and 3h, respectively. The reflux ratio of 3 could provide adequate S(2-)-S/NO3(-)-N ratio (approximately 1:1) to the A&H-DSR unit for obtaining maximum sulfur production. In this system, the maximum production of S(0) reached 90%, but only 60% S(0) was reclaimed from effluent. The S(0) that adhered to the outer layer of granules was deposited in the bottom of the A&H-DSR unit. Finally, the microbial community structure of the corresponding unit at different operational stage were analyzed by 16S rRNA gene based high throughput Illumina MiSeq sequencing and the potential function of dominant species were discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Performance evaluation of startup for a yeast membrane bioreactor (MBRy) treating landfill leachate.

PubMed

Amaral, Míriam C S; Gomes, Rosimeire F; Brasil, Yara L; Oliveira, Sílvia M A; Moravia, Wagner G

2017-12-06

The startup process of a membrane bioreactor inoculated with yeast biomass (Saccharomyces cerevisiae) and used in the treatment of landfill leachate was evaluated. The yeast membrane bioreactor (MBRy) was inoculated with an exogenous inoculum, a granulated active dry commercial bakers' yeast. The MBRy was successfully started up with a progressive increase in the landfill leachate percentage in the MBRy feed and the use of Sabouraud Dextrose Broth. The membrane plays an important role in the startup phase because of its full biomass retention and removal of organic matter. MBRy is a suitable and promising process to treat recalcitrant landfill leachate. After the acclimation period, the COD and NH 3 removal efficiency reached values of 72 ± 3% and 39 ± 2% respectively. MBRy shows a low membrane-fouling potential. The membrane fouling was influenced by soluble microbial products, extracellular polymeric substances, sludge particle size, and colloidal dissolved organic carbon.

Surface-modified microbubbles (colloidal gas aphrons) for nanoparticle removal in a continuous bubble generation-flotation separation system.

PubMed

Zhang, Ming; Guiraud, Pascal

2017-12-01

The treatment of nanoparticle (NP) polluted aqueous suspensions by flotation can be problematic due to the low probability of collision between particles and bubbles. To overcome this limitation, the present work focuses on developing an enhanced flotation technique using the surface-functionalized microbubbles - colloidal gas aphrons (CGAs). The CGA generator was adapted to be air flow rate controlled based on the classical Sebba system; thus it could be well adopted in a continuous flotation process. Cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were employed for CGA creation. Positively surface-charged CTAB-CGAs (∼44.1 μm in size) and negatively surface-charged SDS-CGAs (∼42.1 μm in size) were produced at the optimum stirring speed of 8000 rpm. The half-life of CGAs varied from 100 s to 340 s under the tested conditions, which was largely sufficient for transferring CGAs from bubble generator to flotation cell. The air flow led to less stable CTAB-CGAs but apparently enhanced the stability of SDS-CGAs at higher air flow rates. In the presence of air flow, the drainage behavior was not much related to the type of surfactants. The continuous CGA-flotation trials highlighted the effective separation of silica nanoparticles - the removal efficiencies of different types of SiO 2 NPs could reach approximately 90%-99%; however, at equivalent surfactant concentrations, no greater than 58% of NPs were removed when surfactants and bubbles were separately added into the flotation cell. The SiO 2 NPs with small size were removed more efficiently by the CGA-flotation process. For the flotation with CTAB-CGAs, the neutral and basic initial SNP suspension was recommended, whereas the SDS-CGAs remained high flotation efficiency over all investigated pH. The good performance of CGA-flotation might be interpreted: most of the surfactant molecules well covered/coated on the surfaces of stable CGAs and thus fully contacted with NPs, resulting in the efficient utilization of surfactants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantification of a bacterial secondary metabolite by SERS combined with SLM extraction for bioprocess monitoring.

PubMed

Morelli, Lidia; Andreasen, Sune Zoëga; Jendresen, Christian Bille; Nielsen, Alex Toftgaard; Emnéus, Jenny; Zór, Kinga; Boisen, Anja

2017-11-20

During the last few decades, great advances have been reached in high-throughput design and building of genetically engineered microbial strains, leading to a need for fast and reliable screening methods. We developed and optimized a microfluidic supported liquid membrane (SLM) extraction device and combined it with surface enhanced Raman scattering (SERS) sensing for the screening of a biological process, namely for the quantification of a bacterial secondary metabolite, p-coumaric acid (pHCA), produced by Escherichia coli. The microfluidic device proved to be robust and reusable, enabling efficient removal of interfering compounds from the real samples, reaching more than 13-fold up-concentration of the donor at 10 μL min -1 flow rate. With this method, we quantified pHCA directly from the bacterial supernatant, distinguishing between various culture conditions based on the pHCA production yield. The obtained data showed good correlation with HPLC analysis.

Evaluation program for secondary spacecraft cells. Initial evaluation tests of Eagle-Picher Industries, Incorporated 3.0 ampere-hour nickel-cadmium spacecraft cells

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1973-01-01

The capacity of the cells ranged from 3.58 to 3.97 amperehours during the three capacity tests. Three cells were removed from test, due to high pressure, during the C/10, 24-hour charge at room ambient temperature. The voltage requirement of 1.480 volts was exceeded by the cells during the C/10, 24-hour charge at 20 C, although the end-of-charge voltage was below this value (1.466-1.475 volts). Average capacity out during the 20 C charge efficiency test was 0.84 AH which represents 48% and is below the minimum requirement of 55%. The cells exhibited no pressure decay during the open-circuit stand portion of the pressure versus capacity test, as all cells reached their voltage limit (1.550 volts) before their pressure reached 20 psia with the highest pressure being 8 psia during charge.

[BiOBr promoted the photocatalytic degradation of beta-cypermethrin under visible light].

PubMed

Peng, Yi-Zhu; Zhao, Xiao-Rong; Jia, Man-Ke; Zhou, Wei; Huang, Ying-Ping

2014-05-01

As a visible light photocatalyst, bismuth oxide bromide (BiOBr) was used to catalyze the degradation of beta-cypermethrin (beta-CP). The photocatalytic degradation of beta-CP was studied with gas chromatography. The effects of pH and catalyst dose on the photocatalytic degradation efficiency were discussed. The oxidization and mineralization of beta-CP were detected by chemical oxygen demand (COD) analyzer. The results showed that beta-CP could be effectively degraded under visible light irradiation using BiOBr as the catalyst. At given experimental conditions, the degradation rate of beta-CP reached 94. 68% after 10 h and the COD removal rate reached 67. 99% after 36 h. With the increase of catalyst dose and pH value, the degradation rate was improved. The photocatalytic oxidation species was determined by peroxidase method and terephthalic acid fluorescence method. These results suggested that the photocatalytic degradation process mainly referred to hydroxyl radical ( OH) mechanism.

Remediation of cadmium-contaminated soil by extraction with para-sulphonato-thiacalix[4]arene, a novel supramolecular receptor.

PubMed

Li, Yushuang; Hu, Xiaojun; Song, Xueying; Sun, Tieheng

2012-08-01

Batch extractions were conducted to evaluate the performance of para-sulphonato-thiacalix[4]arene (STC[4]A), a novel supramolecular receptor, for removing cadmium (Cd) from soil. The extraction mechanism was investigated by determination of the conditional stability constants (log K) of the STC[4]A-Cd complex. The influences of various variables were examined, including pH, contact time, and extractant concentration. The Cd extraction efficiency increased with increasing pH, reaching the maximum at pH 11 and then declining at higher pH values. This pH dependence was explained by the variation in the log K value of the STC[4]A-Cd complex along with pH change. When the STC[4]A dose was increased to an STC[4]A:Cd molar ratio of 2.5:1, Cd was exhaustively removed (up to 96.8%). The comparison experiment revealed that the Cd extraction performance of STC[4]A was almost equivalent to that of EDTA and significantly better than that of natural organic acids. STC[4]A extraction could efficiently prevent co-dissolution of soil minerals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Greywater as a sustainable water source: A photocatalytic treatment technology under artificial and solar illumination.

PubMed

Tsoumachidou, Sophia; Velegraki, Theodora; Antoniadis, Apostolos; Poulios, Ioannis

2017-06-15

Greywater considers being a highly reclaimable water source particularly important for water-stressed nations. In this work, heterogeneous photocatalysis using artificial and solar illumination has been applied for the mineralization of simulated light greywater (effluents from dishwashers and kitchen sinks were excluded from the study). The effects on the process' efficiency of TiO 2 P25 catalyst's concentration, initial concentration of H 2 O 2 and Fe 3+ , pH of the solution, as well as the type of radiation, were evaluated in a bench-scale Pyrex reactor and a pilot-scale slurry fountain photoreactor. The treatment efficiency has been followed through the evolution of the organic matter content expresses as dissolved organic carbon (DOC). Best results were obtained with the photo-Fenton-assisted TiO 2 photocatalytic process with 72% DOC removal after 210 min of bench scale treatment, while under the same photocatalytic conditions in the pilot reactor the DOC removal reached almost 64%. Moreover, the decrease in toxicity, phytotoxicity and biodegradability of the simulated wastewater has been observed after solar-induced photocatalytic treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal efficiency of water purifier and adsorbent for iodine, cesium, strontium, barium and zirconium in drinking water.

PubMed

Sato, Itaru; Kudo, Hiroaki; Tsuda, Shuji

2011-01-01

The severe incident of Fukushima Daiichi Nuclear Power Station has caused radioactive contamination of environment including drinking water. Radioactive iodine, cesium, strontium, barium and zirconium are hazardous fission products because of the high yield and/or relatively long half-life. In the present study, 4 pot-type water purifiers and several adsorbents were examined for the removal effects on these elements from drinking water. Iodide, iodate, cesium and barium were removed by all water purifiers with efficiencies about 85%, 40%, 75-90% and higher than 85%, respectively. These efficiencies lasted for 200 l, which is near the recommended limits for use of filter cartridges, without decay. Strontium was removed with initial efficiencies from 70% to 100%, but the efficiencies were slightly decreased by use. Zirconium was removed by two models, but hardly removed by the other models. Synthetic zeolite A4 efficiently removed cesium, strontium and barium, but had no effect on iodine and zirconium. Natural zeolite, mordenite, removed cesium with an efficiency as high as zeolite A4, but the removal efficiencies for strontium and barium were far less than those of zeolite A4. Activated carbon had little removal effects on these elements. In case of radioactive contamination of tap water, water purifiers may be available for convenient decontamination of drinking water in the home.

40 CFR 63.3166 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.3166 Section 63.3166 Protection of Environment... Limitations § 63.3166 How do I determine the add-on control device emission destruction or removal efficiency... emission destruction or removal efficiency as part of the performance test required by § 63.3160. You must...

40 CFR 63.3166 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... device emission destruction or removal efficiency? 63.3166 Section 63.3166 Protection of Environment... Limitations § 63.3166 How do I determine the add-on control device emission destruction or removal efficiency... emission destruction or removal efficiency as part of the performance test required by § 63.3160. You must...

40 CFR 63.4766 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.4766 Section 63.4766 Protection of Environment... Option § 63.4766 How do I determine the add-on control device emission destruction or removal efficiency... emission destruction or removal efficiency as part of the performance test required by § 63.4760. You must...

Virus removal efficiency of Cambodian ceramic pot water purifiers.

PubMed

Salsali, Hamidreza; McBean, Edward; Brunsting, Joseph

2011-06-01

Virus removal efficiency is described for three types of silver-impregnated, ceramic water filters (CWFs) produced in Cambodia. The tests were completed using freshly scrubbed filters and de-ionized (DI) water as an evaluation of the removal efficiency of the virus in isolation with no other interacting water quality variables. Removal efficiencies between 0.21 and 0.45 log are evidenced, which is significantly lower than results obtained in testing of similar filters by other investigators utilizing surface or rain water and a less frequent cleaning regime. Other experiments generally found virus removal efficiencies greater than 1.0 log. This difference may be because of the association of viruses with suspended solids, and subsequent removal of these solids during filtration. Variability in virus removal efficiencies between pots of the same manufacturer, and observed flow rates outside the manufacturer's specifications, suggest tighter quality control and consistency may be needed during production.

Application of Zero-Valent Iron Nanoparticles for the Removal of Aqueous Zinc Ions under Various Experimental Conditions

PubMed Central

Liang, Wen; Dai, Chaomeng; Zhou, Xuefei; Zhang, Yalei

2014-01-01

Application of zero-valent iron nanoparticles (nZVI) for Zn2+ removal and its mechanism were discussed. It demonstrated that the uptake of Zn2+ by nZVI was efficient. With the solids concentration of 1 g/L nZVI, more than 85% of Zn2+ could be removed within 2 h. The pH value and dissolved oxygen (DO) were the important factors of Zn2+ removal by nZVI. The DO enhanced the removal efficiency of Zn2+. Under the oxygen-contained condition, oxygen corrosion gave the nZVI surface a shell of iron (oxy)hydroxide, which could show high adsorption affinity. The removal efficiency of Zn2+ increased with the increasing of the pH. Acidic condition reduced the removal efficiency of Zn2+ by nZVI because the existing H+ inhibited the formation of iron (oxy)hydroxide. Adsorption and co-precipitation were the most likely mechanism of Zn2+ removal by nZVI. The FeOOH-shell could enhance the adsorption efficiency of nZVI. The removal efficiency and selectivity of nZVI particles for Zn2+ were higher than Cd2+. Furthermore, a continuous flow reactor for engineering application of nZVI was designed and exhibited high removal efficiency for Zn2+. PMID:24416439

[Decolorization of dyestuff and dying waste water by laccase solution with self-flocculent mycelial pellets of Coriolus versicolor].

PubMed

Wu, Mianbin; Xia, Liming

2002-06-01

Both laccase production by the white-rot fungus Coriolus versicolor and decolorization of dyestuff and dying waste water with crude solution of laccase were studied in this work. Laccase production meets the definition of secondary metabolism. For laccase production the optimum initial pH is 4.5. Addition of veratryl alcohol or elevated trace metals could both enhance the laccase activity, while Tween80 showed some inhibition. The immobilized mycelia of C. versicolor in polyurethane foam had less laccase production ability than mycelial pellets. A repeated batch cultivation process was found to be a very economical way for laccase harvest. The same pellets could be used for at least 14 times and average laccase activity of each batch could maintain 6.72 IU/mL. This method reduces the enzyme production course, medium consumption and the possibility of contamination, showing high efficient and great economic benefit. Good results were also obtained in decolorization experiments with the crude solution of laccase. With 3.3 IU/mL initial laccase activity, color removal of Acid Orange reached 98.5% after 24 h reaction. Also with 2.6 IU/mL initial laccase activity, color removal of dying waste water reached 93% after 24 h reaction.

[Characteristics of novel wastewater treatment technology by swimming bed combined with aerobic granular sludge].

PubMed

Zhang, Yan; Wang, Yong-sheng; Bai, Yu-hua; Chen, Chen; Lü, Jian; Zhang, Jie

2007-10-01

Swimming bed combined with aerobic granular sludge as a novel technology for wastewater treatment was developed, which was on the basis of the biofilm process and activated sludge process, and results demonstrated notable performance of high-efficiency treatment capability and sludge reduction. Even when hydraulic retention time (HRT) was only at 3.2 h with average COD volumetric loading of 2.03 kg/(m3 x d) and NH4(+)-N of 0.52 kg/(m3 X d), 90.9% of average COD removal rate and 98.3% of NH4(+)-N removal rate were achieved. Aerobic granular sludge appeared with spherical or rod shape after 16 days operation. Mixed liquor suspended solid (MLSS) concentrations in the reactor reached 5,640 mg/L at the highest during operation period, and the average ratio of mixed liquor volatile suspended solid (MLVSS) to MLSS reached 0.87. Furthermore, microscopic observation of biofilm and aerobic granules revealed much presence of protozoa and metazoa on the biofilm and suspended sludge, and this long food chain can contribute to the sludge reduction. Only 0. 175 5 of sludge yields (MLSS/ CODremoved) was obtained in the experiment, which was only about 50% of the conventional aerobic processes.

Variations of floc morphology and extracellular organic matters (EOM) in relation to floc filterability under algae flocculation harvesting using polymeric titanium coagulants (PTCs).

PubMed

Zhang, Weijun; Song, Rongna; Cao, Bingdi; Yang, Xiaofang; Wang, Dongsheng; Fu, Xingmin; Song, Yao

2018-05-01

The work evaluated the algae cells removal efficiency using titanium salt coagulants with different degree of polymerization (PTCs), and the algae cells aggregates and extracellular organic matter (EOM) under chemical flocculation were investigated. The results indicated that PTCs performed well in algae cells flocculation and separation. The main mechanism using PTCs of low alkalisation degree for algae flocculation was associated with charge neutralization, while adsorption bridging and sweep flocculation was mainly responsible for algae removal by PTCs of high alkalisation degree treatment. In addition, the flocs formed by PTC 1.0 showed the best filtration property, and EOM reached the minimum at this time, indicating the flocs formed by PTC 1.0 were more compact than other PTCs, which can be confirmed by SEM analysis. Three-dimensional excitation emission matrix fluorescence (3D-EEM) and high performance size exclusion chromatography (HPSEC) revealed that the EOMs were removed under PTCs flocculation, which improved floc filterability. Copyright © 2018 Elsevier Ltd. All rights reserved.

Veratric acid removal from water by electrochemical oxidation on BDD anode

NASA Astrophysics Data System (ADS)

Jum'h, Inshad; Abdelhay, Arwa; Telfah, Ahmad; Al-Akhras, M.-Ali; Al-Kazwini, Akeel; Rosiwal, Stefan

2018-02-01

The efficiency of boron doped diamond (BDD) in the electrochemical treatment of synthetically contaminated water with veratric acid (VA), one kind of polyphenolic type compounds, is investigated in this work. A BDD electrode was practically fabricated using hot filament chemical vapor deposition (HFCVD). Later on, the BDD electrode was implemented as an anode in a batch electrolytic reactor. The effect of operating factors such as the initial concentration of VA, NaCl addition, and supporting electrolyte type (H2SO4, H3PO4 and Na2SO4) was studied. The chemical oxygen demand (COD) measurements were conducted to study the VA electrolysis kinetics. The experimental data suggested that sodium sulfate was the best supporting electrolyte as the COD removal reached a percentage of 100% using 1 mmol/dm3 as VA concentration. The kinetics of the COD decay of the VA electrolysis were found to obey the pseudo-first order model. Remarkably, the electrolysis process is significantly speeded up once chloride is added to the reaction. The complete COD removal was achieved in 60 minutes of treatment.

Aerobic Biodegradation Characteristic of Different Water-Soluble Azo Dyes.

PubMed

Sheng, Shixiong; Liu, Bo; Hou, Xiangyu; Wu, Bing; Yao, Fang; Ding, Xinchun; Huang, Lin

2017-12-26

This study investigated the biodegradation performance and characteristics of Sudan I and Acid Orange 7 (AO7) to improve the biological dye removal efficiency in wastewater and optimize the treatment process. The dyes with different water-solubility and similar molecular structure were biologically treated under aerobic condition in parallel continuous-flow mixed stirred reactors. The biophase analysis using microscopic examination suggested that the removal process of the two azo dyes is different. Removal of Sudan I was through biosorption, since it easily assembled and adsorbed on the surface of zoogloea due to its insolubility, while AO7 was biodegraded incompletely and bioconverted, the AO7 molecule was decomposed to benzene series and inorganic ions, since it could reach the interior area of zoogloea due to the low oxidation-reduction potential conditions and corresponding anaerobic microorganisms. The transformation of NH₃-N, SO₄ 2- together with the presence of tryptophan-like components confirm that AO7 can be decomposed to non-toxic products in an aerobic bioreactor. This study provides a theoretical basis for the use of biosorption or biodegradation mechanisms for the treatment of different azo dyes in wastewater.

[Preparation of HDTMA-modified Zeolite and Its Performance in Nitro-phenol Adsorption from Wastewaters].

PubMed

Guo, Jun-yuan; Wang, Bin

2016-05-15

In this study, natural zeolite was modified by HDTMA. Effects of the modified conditions, HDTMA-modified zeolite doses, solution pH values, and reaction time on nitro-phenol removal were investigated, and the adsorption kinetics and isotherms were discussed. Compared with natural zeolite, HDTMA-modified zeolite showed better performance in nitro-phenol removal. An adsorption capacity of 2.53 mg · g⁻¹ was achieved when the concentration of HDTMA solution (pH = 10) was 1.2% in preparation of modified zeolite. This adsorption capacity was higher than that obtained by natural zeolite (0.54 mg · g⁻¹). In adsorption tests, when HDTMA- modified zeolite dose was adjusted to 8 g · L⁻¹, the removal efficiency of nitro-phenol reached 93.9% after 90 min reaction, with wastewater pH of 6. Furthermore, the nitro-phenol adsorption process could be well fitted to the pseudo-first-order kinetics model (R² > 0.90), whereas the adsorption isotherm results indicated that Langmuir model provided the best fitting for the equilibrium data at different temperatures, with R² of higher than 0.90.

Resuscitation of starved anaerobic ammonium oxidation sludge system: Impacts of repeated short-term starvation.

PubMed

Ye, Lihong; Li, Dong; Zhang, Jie; Zeng, Huiping

2018-05-04

Starvation of biomass is common during underloading of bioreactors or sludge storage in biological wastewater treatment industries. The aim of this work was to study the impact of starvation modes on the nitrogen removal capacity of anaerobic ammonium oxidation (anammox) process in sequencing batch reactor (SBR). The repeated short-term starvation and reactivation experiments were performed to evaluate the response of anammox sludge system in the condition of 27 ± 1.5 °C and 320 min HRT. Moreover, the nitrogen removal ability of the anammox process was reactivated rapidly in the low substrate condition, then the total nitrogen (TN) removal efficiency reached 82.5%, with the effluent TN of around 14.6 mgNL -1 . The repeated short-term starvation (1 day-4 days) and recovery mode could improve the tolerance and apparent activity of anammox sludge system. The dominant species of general anaerobic ammonium oxidation bacteria (AnAOB) was Candidatus Brocadia, which had better self-adaption to repeated starvation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rapid and efficient treatment of wastewater with high-concentration heavy metals using a new type of hydrogel-based adsorption process.

PubMed

Zhou, Guiyin; Liu, Chengbin; Chu, Lin; Tang, Yanhong; Luo, Shenglian

2016-11-01

In this study, a new type of double-network hydrogel sorbent was developed to remove heavy metals in wastewater. The amino-functionalized Starch/PAA hydrogel (NH2-Starch/PAA) could be conducted in a wide pH and the adsorption process could rapidly achieve the equilibrium. The adsorption capacity got to 256.4mg/g for Cd(II). Resultantly, even though Cd(II) concentration was as high as 180mg/L, the Cd(II) could be entirely removed using 1g/L sorbent. Furthermore, the desirable mechanical durability of the adsorbent allowed easy separation and reusability. In the fixed-bed column experiments, the treatment volume of the effluent with a high Cd(II) concentration of 200mg/L reached 2400BV (27.1L) after eight times cycle. The NH2-Starch/PAA overcame the deficiency of conventional sorbents that could not effectively treat the wastewater with relatively high metal concentrations. This work provides a new insight into omnidirectional enhancement of sorbents for removing high-concentration heavy metals in wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visible-light-enhanced Cr(VI) reduction at Pd-decorated silicon nanowire photocathode in photoelectrocatalytic microbial fuel cell.

PubMed

Han, He-Xing; Shi, Chen; Zhang, Nan; Yuan, Li; Sheng, Guo-Ping

2018-10-15

Hexavalent chromium (Cr(VI)) is a prominent toxic metal with significant adverse human health effects. Photocatalytic reduction of Cr(VI) to less-toxic trivalent chromium (Cr(III)) is a promising method for removing Cr(VI) from aquatic environments. However, this technique often suffers from electron-hole recombination of semiconductors and poor reduction efficiency. The photoelectrocatalytic microbial fuel cell (Photo-MFC), which can use wastewater and light to recover electricity, has recently been proven to improve the separation of photocarriers of semiconductors and enhance cathodic reduction of pollutants. Here, the reduction of Cr(VI) was investigated in a Photo-MFC with a Pd-decorated p-type silicon nanowire (Pd/SiNW) photocathode and a bioanode under visible light. The Cr(VI) reduction efficiency reached 98.7% in 8 h under visible light, which was much higher than that under dark condition (56.2%) and open-circuit condition (19.4%). The enhanced Cr(VI) removal was mainly attributed to the synergistic effect of Pd/SiNW photocathode and bioanode. Cr(VI) reduction in the Photo-MFC fitted well with pseudo-first-order kinetics. The kinetics constants and reduction efficiencies of Cr(VI) decreased with the increase of pH, initial Cr(VI) concentration and external resistance. This work provides a promising alternative to mitigate Cr(VI) pollution in aquatic environments. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of calf death loss on cloned cattle herd derived from somatic cell nuclear transfer: clones with congenital defects would be removed by the death loss.

PubMed

Watanabe, Shinya

2013-09-01

To increase public understanding on cloned cattle derived from somatic cell nuclear transfer (SCNT), the present review describes the effect of calf death loss on an SCNT cattle herd. The incidence of death loss in SCNT cattle surviving more than 200 days reached the same level as that in conventionally bred cattle. This process could be considered as removal of SCNT cattle with congenital defects caused by calf death loss. As a result of comparative studies of SCNT cattle and conventionally bred cattle, the substantial equivalences in animal health status, milk and meat productive performance have been confirmed. Both sexes of SCNT cattle surviving to adulthood were fertile and their reproductive performance, including efficiency of progeny production, was the same as that in conventionally bred cattle. The presence of substantial equivalence between their progeny and conventionally bred cattle also existed. Despite these scientific findings, the commercial use of food products derived from SCNT cattle and their progeny has not been allowed by governments for reasons including the lack of public acceptance of these products and the low efficiency of animal SCNT. To overcome this situation, communication of the low risk of SCNT technology and research to improve SCNT efficiency are required. © 2013 Japanese Society of Animal Science.

Novel insights into anoxic/aerobic(1)/aerobic(2) biological fluidized-bed system for coke wastewater treatment by fluorescence excitation-emission matrix spectra coupled with parallel factor analysis.

PubMed

Ou, Hua-Se; Wei, Chao-Hai; Mo, Ce-Hui; Wu, Hai-Zhen; Ren, Yuan; Feng, Chun-Hua

2014-10-01

Fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) was applied to investigate the contaminant removal efficiency and fluorescent characteristic variations in a full scale coke wastewater (CWW) treatment plant with a novel anoxic/aerobic(1)/aerobic(2) (A/O(1)/O(2)) process, which combined with internal-loop fluidized-bed reactor. Routine monitoring results indicated that primary contaminants in CWW, such as phenols and free cyanide, were removed efficiently in A/O(1)/O(2) process (removal efficiency reached 99% and 95%, respectively). Three-dimensional excitation-emission matrix fluorescence spectroscopy and PARAFAC identified three fluorescent components, including two humic-like fluorescence components (C1 and C3) and one protein-like component (C2). Principal component analysis revealed that C1 and C2 correlated with COD (correlation coefficient (r)=0.782, p<0.01 and r=0.921, p<0.01), respectively) and phenols (r=0.796, p<0.01 and r=0.914, p<0.01, respectively), suggesting that C1 and C2 might be associated with the predominating aromatic contaminants in CWW. C3 correlated with mixed liquor suspended solids (r=0.863, p<0.01) in fluidized-bed reactors, suggesting that it might represent the biological dissolved organic matter. In A/O(1)/O(2) process, the fluorescence intensities of C1 and C2 consecutively decreased, indicating the degradation of aromatic contaminants. Correspondingly, the fluorescence intensity of C3 increased in aerobic(1) stage, suggesting an increase of biological dissolved organic matter. Copyright © 2014 Elsevier Ltd. All rights reserved.

Behaviour of a full-scale expanded bed reactor with overlaid anaerobic and aerobic zones for domestic wastewater treatment.

PubMed

Mendonça, N M; Siman, R R; Niciura, C L; Campos, J R

2006-01-01

This paper presents the behaviour of a full-scale expanded bed reactor (160 m3) with overlaid anaerobic and aerobic zones used for municipal wastewater treatment. The research was carried out in two experimental steps: anaerobic and anaerobic-aerobic conditions, and the experimental results presented in this paper refer to four months of reactor operation. In the anaerobic condition, after inoculation and 60 days of operation, the reactor treating 3.40 kg CODm(-3)d(-1) for thetaH of 2.69 h, reached mean removal efficiencies of 76% for BOD, 72% for COD, and 80% for TSS, when the effluent presented mean values of 225 mg.L(-1) of COD, 98 mg.L(-1) of BOD and 35 mg.L(-1) of TSS. Under these conditions, for nitrogen loading of 0.27 kgN.m(-3)d(-1), the reactor generated an effluent with mean N-org. of 8 mg.L(-1) and N-ammon. of 37 mg.L(-1), demonstrating high potential of ammonification. For the anaerobic-aerobic condition (118th day) the system was operated with thetaH of 5.38 h presented mean removal efficiencies of 84% for BOD, 79% for COD, 76% for TSS, and 30% for TKN. The reactor's operation time was less than two months, which was not long enough to reach nitrification. Regarding the obtained results, this research confirmed that this reactor is configured as a flexible and adequate alternative for the treatment of sewage, requiring relatively small area and only thetaH of 10 h that can be adjusted to the local circumstances.

Power generation from furfural using the microbial fuel cell

NASA Astrophysics Data System (ADS)

Luo, Yong; Liu, Guangli; Zhang, Renduo; Zhang, Cuiping

Furfural is a typical inhibitor in the ethanol fermentation process using lignocellulosic hydrolysates as raw materials. In the literature, no report has shown that furfural can be utilized as the fuel to produce electricity in the microbial fuel cell (MFC), a device that uses microbes to convert organic compounds to generate electricity. In this study, we demonstrated that electricity was successfully generated using furfural as the sole fuel in both the ferricyanide-cathode MFC and the air-cathode MFC. In the ferricyanide-cathode MFC, the maximum power densities reached 45.4, 81.4, and 103 W m -3, respectively, when 1000 mg L -1 glucose, a mixture of 200 mg L -1 glucose and 5 mM furfural, and 6.68 mM furfural were used as the fuels in the anode solution. The corresponding Coulombic efficiencies (CE) were 4.0, 7.1, and 10.2% for the three treatments, respectively. For pure furfural as the fuel, the removal efficiency of furfural reached up to 95% within 12 h. In the air-cathode MFC using 6.68 mM furfural as the fuel, the maximum values of power density and CE were 361 mW m -2 (18 W m -3) and 30.3%, respectively, and the COD removal was about 68% at the end of the experiment (about 30 h). Increase in furfural concentrations from 6.68 to 20 mM resulted in increase in the maximum power densities from 361 to 368 mW m -2, and decrease in CEs from 30.3 to 20.6%. These results indicated that some toxic and biorefractory organics such as furfural might still be suitable resources for electricity generation using the MFC technology.

Statistical estimate of mercury removal efficiencies for air pollution control devices of municipal solid waste incinerators.

PubMed

Takahashi, Fumitake; Kida, Akiko; Shimaoka, Takayuki

2010-10-15

Although representative removal efficiencies of gaseous mercury for air pollution control devices (APCDs) are important to prepare more reliable atmospheric emission inventories of mercury, they have been still uncertain because they depend sensitively on many factors like the type of APCDs, gas temperature, and mercury speciation. In this study, representative removal efficiencies of gaseous mercury for several types of APCDs of municipal solid waste incineration (MSWI) were offered using a statistical method. 534 data of mercury removal efficiencies for APCDs used in MSWI were collected. APCDs were categorized as fixed-bed absorber (FA), wet scrubber (WS), electrostatic precipitator (ESP), and fabric filter (FF), and their hybrid systems. Data series of all APCD types had Gaussian log-normality. The average removal efficiency with a 95% confidence interval for each APCD was estimated. The FA, WS, and FF with carbon and/or dry sorbent injection systems had 75% to 82% average removal efficiencies. On the other hand, the ESP with/without dry sorbent injection had lower removal efficiencies of up to 22%. The type of dry sorbent injection in the FF system, dry or semi-dry, did not make more than 1% difference to the removal efficiency. The injection of activated carbon and carbon-containing fly ash in the FF system made less than 3% difference. Estimation errors of removal efficiency were especially high for the ESP. The national average of removal efficiency of APCDs in Japanese MSWI plants was estimated on the basis of incineration capacity. Owing to the replacement of old APCDs for dioxin control, the national average removal efficiency increased from 34.5% in 1991 to 92.5% in 2003. This resulted in an additional reduction of about 0.86Mg emission in 2003. Further study using the methodology in this study to other important emission sources like coal-fired power plants will contribute to better emission inventories. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of flow rate on growth and oxygen consumption of biofilm in gravity sewer.

PubMed

Xu, Jingwei; Li, Muzhi; He, Qiang; Sun, Xingfu; Zhou, Xiangren; Su, Zhenping; Ai, Hainan

2017-01-01

The function of sewer as reactors must rely on the biofilm in it. In this paper, the formation, structure, oxygen transfer, and activity of the biofilm under different hydraulic conditions were studied by the microelectrode technology, oxygen uptake rate (OUR) technology, and 454 high-throughput pyrosequencing technology. Results showed that when the wall-shear stresses were 1.12, 1.29, and 1.45 Pa, the porosity of the steady-state biofilm were 69.1, 64.4, and 55.1 %, respectively. The maximum values of OUR were 0.033, 0.027, and 0.022 mg/(L*s), respectively, and the COD removal efficiency in the sewers reached 40, 35, and 32 %, respectively. The research findings had an important significance on how to improve the treatment efficiency of the sewers. Fig. a Graphical Abstract.

The influence of small-scale interlayer heterogeneity on DDT removal efficiency for flushing technology

NASA Astrophysics Data System (ADS)

Wang, Xingwei; Chen, Jiajun

2017-06-01

With an aim to investigate the influence of small-scale interlayer heterogeneity on DDT removal efficiency, batch test including surfactant-stabilized foam flushing and solution flushing were carried out. Two man-made heterogeneous patterns consisting of coarse and fine quartz sand were designed to reveal the influencing mechanism. Moreover, the removal mechanism and the corresponding contribution by foam flushing were quantitatively studied. Compared with surfactant solution flushing, the DDT removal efficiency by surfactant-stabilized foam flushing increased by 9.47% and 11.28% under heterogeneous patterns 1 and 2, respectively. The DDT removal contributions of improving sweep efficiency for heterogeneous patterns 1 and 2 by foam flushing were 40.82% and 45.98%, and the contribution of dissolving capacity were 59.18% and 54.02%, respectively. The dissolving capacity of DDT played a major role in DDT removal efficiency by foam flushing under laboratory conditions. And the DDT removal contribution of significant improving sweep efficiency was higher than that of removal decline caused by weak solubilizing ability of foam film compared with solution flushing. The obtained results indicated that the difference of DDT removal efficiency by foam flushing was decreased under two different heterogeneous patterns with the increase of the contribution of improving foam flushing sweep efficiency. It suggested that foam flushing can reduce the disturbance from interlayer heterogeneity in remediating DDT contaminated heterogeneous medium.

Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell.

PubMed

Bergmann, Victor W; Weber, Stefan A L; Javier Ramos, F; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Li, Dan; Domanski, Anna L; Lieberwirth, Ingo; Ahmad, Shahzada; Berger, Rüdiger

2014-09-22

Perovskite-sensitized solar cells have reached power conversion efficiencies comparable to commercially available solar cells used for example in solar farms. In contrast to silicon solar cells, perovskite-sensitized solar cells can be made by solution processes from inexpensive materials. The power conversion efficiency of these cells depends substantially on the charge transfer at interfaces. Here we use Kelvin probe force microscopy to study the real-space cross-sectional distribution of the internal potential within high efficiency mesoscopic methylammonium lead tri-iodide solar cells. We show that the electric field is homogeneous through these devices, similar to that of a p-i-n type junction. On illumination under short-circuit conditions, holes accumulate in front of the hole-transport layer as a consequence of unbalanced charge transport in the device. After light illumination, we find that trapped charges remain inside the active device layers. Removing these traps and the unbalanced charge injection could enable further improvements in performance of perovskite-sensitized solar cells.

From by-product to valuable components: Efficient enzymatic conversion of lactose in whey using β-galactosidase from Streptococcus thermophilus.

PubMed

Geiger, Barbara; Nguyen, Hoang-Minh; Wenig, Stefanie; Nguyen, Hoang Anh; Lorenz, Cindy; Kittl, Roman; Mathiesen, Geir; Eijsink, Vincent G H; Haltrich, Dietmar; Nguyen, Thu-Ha

2016-12-15

β-Galactosidase from Streptococcus thermophilus was overexpressed in a food-grade organism, Lactobacillus plantarum WCFS1. Laboratory cultivations yielded 11,000 U of β-galactosidase activity per liter of culture corresponding to approximately 170 mg of enzyme. Crude cell-free enzyme extracts obtained by cell disruption and subsequent removal of cell debris showed high stability and were used for conversion of lactose in whey permeate. The enzyme showed high transgalactosylation activity. When using an initial concentration of whey permeate corresponding to 205 g L -1 lactose, the maximum yield of galacto-oligosaccharides (GOS) obtained at 50°C reached approximately 50% of total sugar at 90% lactose conversion, meaning that efficient valorization of the whey lactose was obtained. GOS are of great interest for both human and animal nutrition; thus, efficient conversion of lactose in whey into GOS using an enzymatic approach will not only decrease the environmental impact of whey disposal, but also create additional value.

The Use of Permeable Barriers to Inhibit Virus Migration in the Subsurface

NASA Astrophysics Data System (ADS)

Schulze-Makuch, D.; Guan, H.; Totten, J.; Couroux, E.; Endley, S.; Hielscher, F.; Emmert, S.; Pillai, S. D.

2001-12-01

Ground water is susceptible to fecal contamination due to leaking sewer lines, faulty septic tanks and careless disposal of septic wastes; a problem especially common in low-income areas with no public sewage system. Under these conditions, viral and bacterial infection rates have been shown to increase. However, potential for viral infections can be reduced if the viruses are prevented from reaching the drinking water wells. Laboratory and field studies were conducted to determine whether iron-coated sand (ICS), pure zeolite (PZ) and surfactant modified zeolites (SMZ) could be used to retard virus migration in soils. In the laboratory, using a model aquifer and MS2 bacteriophage (as an enteric virus indicator) we showed that ICS and especially SMZ was able to remove more than 90 % of the injected viruses under various conditions. The removal efficiency of viruses was also tested under field conditions using septic effluent and a constructed submerged wetland. The performance of the wetland was greatly enhanced when using SMZ as filter pack for a pumping well that withdrew water at a downstream location from the wetland. Our results suggest that submerged wetlands, particularly if combined with a pumping well that has a filter pack consisting of surfactant modified zeolite (rather than the usual sand and gravel pack), are efficient in removing viruses from septic effluent. The permeable barrier materials tested here are economical and could significantly reduce the potential for viral contamination of drinking water wells. >http://www.geo.utep.edu/pub/dirksm/geobiowater/geobiowater.htm

Effects of sludge recirculation rate and mixing time on performance of a prototype single-stage anaerobic digester for conversion of food wastes to biogas and energy recovery.

PubMed

Ratanatamskul, Chavalit; Saleart, Tawinan

2016-04-01

Food wastes have been recognized as the largest waste stream and accounts for 39.25 % of total municipal solid waste in Thailand. Chulalongkorn University has participated in the program of in situ energy recovery from food wastes under the Ministry of Energy (MOE), Thailand. This research aims to develop a prototype single-stage anaerobic digestion system for biogas production and energy recovery from food wastes inside Chulalongkorn University. Here, the effects of sludge recirculation rate and mixing time were investigated as the main key parameters for the system design and operation. From the results obtained in this study, it was found that the sludge recirculation rate of 100 % and the mixing time of 60 min per day were the most suitable design parameters to achieve high efficiencies in terms of chemical oxygen demand (COD), total solids (TS), and total volatile solid (TVS) removal and also biogas production by this prototype anaerobic digester. The obtained biogas production was found to be 0.71 m(3)/kg COD and the composition of methane was 61.6 %. Moreover, the efficiencies of COD removal were as high as 82.9 % and TVS removal could reach 83.9 % at the optimal condition. Therefore, the developed prototype single-stage anaerobic digester can be highly promising for university canteen application to recover energy from food wastes via biogas production.

Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation.

PubMed

Tatoulis, Triantafyllos; Stefanakis, Alexandros; Frontistis, Zacharias; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Mantzavinos, Dionissios; Vayenas, Dimitrios V

2017-01-01

The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost. Previously, biological filters were combined with electrooxidation to treat table olive washing water. Although this combination was successful in reducing pollutant loads, its cost could be further reduced. Constructed wetlands could be an eligible treatment method for integrated table olive washing water treatment as they have proved tolerant to high organic matter and phenol loads. Two pilot-scale horizontal subsurface constructed wetlands, one planted and one unplanted, were combined with a biological filter and electrooxidation over a boron-doped diamond anode to treat table olive washing water. In the biological filter inlet, chemical oxygen demand (COD) concentrations ranged from 5500 to 15,000 mg/L, while mean COD influent concentration in the constructed wetlands was 2800 mg/L. The wetlands proved to be an efficient intermediate treatment stage, since COD removal levels for the planted unit reached 99 % (mean 70 %), while the unplanted unit presented removal rates of around 65 %. Moreover, the concentration of phenols in the effluent was typically below 100 mg/L. The integrated trickling filter-constructed wetland-electrooxidation treatment system examined here could mineralize and decolorize table olive washing water and fully remove its phenolic content.

Removal of methylene blue from its aqueous solution by froth flotation: hydrophobic silica nanoparticle as a collector

NASA Astrophysics Data System (ADS)

Hu, Nan; Liu, Wei; Ding, Linlin; Wu, Zhaoliang; Yin, Hao; Huang, Di; Li, Hongzhen; Jin, Lixue; Zheng, Huijie

2017-02-01

Dye pollution has been a severe problem faced by worldwide environmentalists. The use of nanoparticles as adsorbents has attracted widespread interests for effectively removing dyes, while the separation of them from an aqueous solution is a difficult and important subject. For achieving the simultaneous removal of methylene blue (MB) and nanoadsorbents, this work utilized a commercial hydrophobic silica nanoparticle (SNP) (200.0 ± 10.0 nm in average particle size) as a collector and then developed a novel froth flotation technology without using any surfactants. Under the suitable conditions of anhydrous ethanol dosage of 8 mL, pH of 9.0, SNP concentration of 600 mg/L, and flotation column height of 600 mm, the removal efficiencies of MB and SNPs and the volume ratio reached 91.1 ± 4.6%, 93.9 ± 4.7%, and 10.5 ± 0.5, respectively. Subsequently, the recovered MB-adsorbed SNPs in the foamate were separated by free setting due to their high concentration and massive agglomeration. After free setting, MB could be effectively separated from the recovered MB-adsorbed SNPs by using ethanol at pH 2.0 and repeating five cycles of washing-centrifugation. Additionally, the regenerated SNPs could be reused for removing MB up to five times. Overall, this work had a significant meaning for the treatment of dye-contaminated wastewaters.

Magnetic biochar combining adsorption and separation recycle for removal of chromium in aqueous solution.

PubMed

Xin, Ouyang; Yitong, Han; Xi, Cao; Jiawei, Chen

2017-03-01

Biochar has been developed in recent years for the removal of contaminants such as Cr (VI) in water. The enhancement of the adsorption capacity of biochar and its recyclable use are still challenges. In this study, magnetic biochar derived from corncobs and peanut hulls was synthesized under different pyrolysis temperatures after pretreating the biomass with a low concentration of 0.5 M FeCl 3 solution. The morphology, specific surface area, saturation magnetization and Fourier transform infrared spectroscopy (FT-IR) spectra were characterized for biochar. The magnetic biochar performed well in combining adsorption and separation recycle for the removal of Cr (VI) in water. The Cr (VI) adsorbance of the biochar was increased with the increase in pyrolysis temperature, and the magnetic biochar derived from corncobs showed better performance for both magnetization and removal of Cr (VI) than that from peanut hulls. The Langmuir model was used for the isothermal adsorption and the maximum Cr (VI) adsorption capacity of corncob magnetic biochar pyrolyzed at 650 °C reached 61.97 mg/g. An alkaline solution (0.1 M NaOH) favored the desorption of Cr (VI) from the magnetic biochar, and the removal of Cr (VI) still remained around 77.6% after four cycles of adsorption-desorption. The results showed that corncob derived magnetic biochar is a potentially efficient and recoverable adsorbent for remediation of heavy metals in water.

Investigating waste rock, tailings, slag and coal ash clinker as adsorbents for heavy metals: Batch and column studies

NASA Astrophysics Data System (ADS)

Letina, D.; Letshwenyo, W. M.

2018-06-01

Wastewater from the mining industry is a concern because most of the time it contains heavy metals with concentrations above permissible levels, posing a threat to terrestrial and aquatic life. The study was conducted to evaluate the effectiveness of locally available waste materials (waste rock, tailings, coal ash clinker, and slag) generated by BCL (Ltd) mine, a copper and nickel mining and smelting company in Botswana, for removal of nickel and copper from the real mining wastewater. Batch adsorption studies were conducted to establish the adsorptive efficiency and kinetics of each media with respect to nickel and copper ions. The best media was further evaluated through fixed bed column studies at 24 and 48 h empty bed contact time. The results indicate that the percentage removal for coal ash clinker, waste rock, smelter slag and tailings was 98%, 15%, 3% and -3% with respect to copper ions, and 46%, 9%, 7% and 2% with respect to nickel ions for each media respectively. Coal ash clinker followed pseudo first order kinetic model and Langmuir isotherm model with respect to nickel ions indicating the dominance of physisorption and mono layer coverage respectively. The Langmuir separation factor (RL) was 0.37 suggesting favourable adsorption onto the media. Fixed bed column studies revealed that copper was completely retained in the bed at both 24 and 48 h contact times. In the case of nickel, removal efficiency ranged between 83% and 99% when contact time was 48 h and between 68% and 99% when the contact time was reduced to 24 h. Breakthrough was not reached after 19 bed volumes. It can be concluded that coal ash clinker is a better candidate for the removal of copper and nickel ions from mining wastewater.

High performance of a unique mesoporous polystyrene-based adsorbent for blood purification

PubMed Central

Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

2017-01-01

A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient. PMID:28149527

High performance of a unique mesoporous polystyrene-based adsorbent for blood purification.

PubMed

Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

2017-02-01

A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient.

Microlith-based Structured Sorbent for Carbon Dioxide, Humidity, and Trace Contaminant Control in Manned Space Habitats

NASA Technical Reports Server (NTRS)

Junaedi, Christian; Roychoudhury, SUbir; Howard, David F.; Perry, Jay L.; Knox, James C.

2011-01-01

To support continued manned space exploration, the development of atmosphere revitalization systems that are lightweight, compact, durable, and power efficient is a key challenge. The systems should be adaptable for use in a variety of habitats and should offer operational functionality to either expel removed constituents or capture them for closedloop recovery. As mission durations increase and exploration goals reach beyond low earth orbit, the need for regenerable adsorption processes for continuous removal of CO2 and trace contaminants from cabin air becomes critical. Precision Combustion, Inc. (PCI) and NASA Marshall (MSFC) have been developing an Engineered Structured Sorbents (ESS) approach based on PCI s patented Microlith technology to meet the requirements of future, extended human spaceflight explorations. This technology offers the inherent performance and safety attributes of zeolite and other sorbents with greater structural integrity, regenerability, and process control, thereby providing potential durability and efficiency improvements over current state-of-the-art systems. The major advantages of the ESS explored in this study are realized through the use of metal substrates to provide structural integrity (i.e., less partition of sorbents) and enhanced thermal control during the sorption process. The Microlith technology also offers a unique internal resistive heating capability that shows potential for short regeneration time and reduced power requirement compared to conventional systems. This paper presents the design, development, and performance results of the integrated adsorber modules for removing CO2, water vapor, and trace chemical contaminants. A related effort that utilizes the adsorber modules for sorption of toxic industrial chemicals is also discussed. Finally, the development of a 4-person two-leg ESS system for continuous CO2 removal is also presented.

Electromigration of Mn, Fe, Cu and Zn with citric acid in contaminated clay.

PubMed

Pazos, M; Gouveia, S; Sanroman, M A; Cameselle, C

2008-07-01

Metal reactivity, speciation and solubility have an important influence in its transportation through a porous matrix by electrokinetics and, therefore, they dramatically affect the removal efficiency. This work deals with the effect of solubility and transport competition among several metals (Mn, Fe, Cu and Zn) during their transport through polluted clay. The unenhancement electrokinetic treatment results in a limited removal of the tested metals because they were retained into the kaolinite sample by the penetration of the alkaline front. Metals showed a removal degree in accordance with the solubility of the corresponding hydroxide and its formation pH. In 7 days of treatment, the removal results were: 75.6% of Mn; 68.5% of Zn, 40.6% of Cu and 14.8% of Fe. In order to avoid the negative effects of the basic front generated at the cathode, two different techniques were proposed and tested: the addition of citric acid as complexing agent to the polluted kaolinite sample and the use of citric acid to control de pH on the cathode chamber. Both techniques are based on the capability of citric acid to act as a complexing and neutralizing agent. Almost complete removal of Mn, Cu and Zn was achieved when citric acid was used (as neutralizing or complexing agent). But Fe only reached 33% of removal because it formed a negatively charged complex with citrate that retarded its transportation to the cathode.

Removal of cationic pollutants from water by xanthated corn cob: optimization, kinetics, thermodynamics, and prediction of purification process.

PubMed

Kostić, Miloš; Đorđević, Miloš; Mitrović, Jelena; Velinov, Nena; Bojić, Danijela; Antonijević, Milan; Bojić, Aleksandar

2017-07-01

The removal of Cr(III) ions and methylene blue (MB) from aqueous solutions by xanthated corn cob (xCC) in batch conditions was investigated. The sorption capacity of xCC strongly depended of the pH, and increase when the pH rises. The kinetics was well fitted by pseudo-second-order and Chrastil's model. Sorption of Cr(III) ions and MB on xCC was rapid during the first 20 min of contact time and, thereafter, the biosorption rate decrease gradually until reaching equilibrium. The maximum sorption capacity of 17.13 and 83.89 mg g -1 for Cr(III) ions and MB, respectively, was obtained at 40 °C, pH 5, and sorbent dose 4 g dm -3 for removal of Cr(III) ions and 1 g dm -3 for removal of MB. The prediction of purification process was successfully carried out, and the verification of theoretically calculated amounts of sorbent was confirmed by using packed-bed column laboratory system with recirculation of the aqueous phase. The wastewater from chrome plating industry was successfully purified, i.e., after 40 min concentration of Cr(III) ions was decreased lower than 0.1 mg dm -3 . Also, removal of MB from the river water was successfully carried out and after 40 min, removal efficiency was about 94%.

Efficient removal of perfluorooctane sulfonate from aqueous film-forming foam solution by aeration-foam collection.

PubMed

Meng, Pingping; Deng, Shubo; Maimaiti, Ayiguli; Wang, Bin; Huang, Jun; Wang, Yujue; Cousins, Ian T; Yu, Gang

2018-07-01

Aqueous film-forming foams (AFFFs) used in fire-fighting are one of the main contamination sources of perfluorooctane sulfonate (PFOS) to the subterranean environment, requiring high costs for remediation. In this study, a method that combined aeration and foam collection was presented to remove PFOS from a commercially available AFFF solution. The method utilized the strong surfactant properties of PFOS that cause it to be highly enriched at air-water interfaces. With an aeration flow rate of 75 mL/min, PFOS removal percent reached 96% after 2 h, and the PFOS concentration in the collected foam was up to 6.5 mmol/L, beneficial for PFOS recovery and reuse. Increasing the aeration flow rate, ionic strength and concentration of co-existing surfactant, as well as decreasing the initial PFOS concentration, increased the removal percents of PFOS by increasing the foam volume, but reduced the enrichment of PFOS in the foams. With the assistance of a co-existing hydrocarbon surfactant, PFOS removal percent was above 99.9% after aeration-foam collection for 2 h and the enrichment factor exceeded 8400. Aeration-foam collection was less effective for short-chain perfluoroalkyl substances due to their relatively lower surface activity. Aeration-foam collection was found to be effective for the removal of high concentrations of PFOS from AFFF-contaminated wastewater, and the concentrated PFOS in the collected foam can be reused. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrochemical treatment of domestic wastewater using boron-doped diamond and nanostructured amorphous carbon electrodes.

PubMed

Daghrir, Rimeh; Drogui, Patrick; Tshibangu, Joel; Delegan, Nazar; El Khakani, My Ali

2014-05-01

The performance of the electrochemical oxidation process for efficient treatment of domestic wastewater loaded with organic matter was studied. The process was firstly evaluated in terms of its capability of producing an oxidant agent (H2O2) using amorphous carbon (or carbon felt) as cathode, whereas Ti/BDD electrode was used as anode. Relatively high concentrations of H2O2 (0.064 mM) was produced after 90 min of electrolysis time, at 4.0 A of current intensity and using amorphous carbon at the cathode. Factorial design and central composite design methodologies were successively used to define the optimal operating conditions to reach maximum removal of chemical oxygen demand (COD) and color. Current intensity and electrolysis time were found to influence the removal of COD and color. The contribution of current intensity on the removal of COD and color was around 59.1 and 58.8%, respectively, whereas the contribution of treatment time on the removal of COD and color was around 23.2 and 22.9%, respectively. The electrochemical treatment applied under 3.0 A of current intensity, during 120 min of electrolysis time and using Ti/BDD as anode, was found to be the optimal operating condition in terms of cost/effectiveness. Under these optimal conditions, the average removal rates of COD and color were 78.9 ± 2 and 85.5 ± 2 %, whereas 70% of total organic carbon removal was achieved.

Polyethyleneimine-carbon nanotube polymeric nanocomposite adsorbents for the removal of Cr6+ from water

NASA Astrophysics Data System (ADS)

Sambaza, Shepherd S.; Masheane, Monaheng L.; Malinga, Soraya P.; Nxumalo, Edward N.; Mhlanga, Sabelo D.

2017-08-01

This work reports on the synthesis of multi-walled carbon nanotubes (MWCNTs) and their use in branched polyethyleneimine-multiwalled carbon nanotube (PEI-MWCNT) polymeric nanocomposite adsorbents for the removal of Cr6+ from contaminated water. The nanostructured materials were characterized using TEM, Raman, FTIR, BET surface area and zeta potential measurements. TEM confirmed the average diameter of the MWCNTs to be 25 nm. The point of zero-charge of PEI was at pH 8 and that of PEI-MWCNTs was at pH 7.7. FTIR analysis confirmed the formation of a new bond (-Cdbnd O at 1716 cm-1) between the functional groups on the MWCNTs and PEI. Batch adsorption and kinetic studies showed that the PEI-MWCNT nanocomposite materials were more efficient in the removal of Cr6+ solution from water samples. The optimum conditions for adsorption were pH ≤ 4, contact time of 60 min. When the PEI-MWCNT dosage was increased the adsorption capacity increased. The kinetic adsorption data obtained for Cr6+ solution followed pseudo-second order model. The adsorption of Cr6+ solution reached equilibrium within 60 min of contact time with a removal of 99%. The adsorbents were effective even after 5 cycles of use.

Performance of wind-powered soil electroremediation process for the removal of 2,4-D from soil.

PubMed

Souza, F L; Llanos, J; Sáez, C; Lanza, M R V; Rodrigo, M A; Cañizares, P

2016-04-15

In this work, it is studied a wind-powered electrokinetic soil flushing process for the removal of pesticides from soil. This approach aims to develop an eco-friendly electrochemical soil treatment technique and to face the in-situ treatment of polluted soils at remote locations. Herbicide 2,4 dichlorophenoxyacetic acid (2,4-D) is selected as a model pollutant for the soil treatment tests. The performance of the wind-powered process throughout a 15 days experiment is compared to the same remediation process powered by a conventional DC power supply. The wind-powered test covered many different wind conditions (from calm to near gale), being performed 20.7% under calm conditions and 17% under moderate or gentle breeze. According to the results obtained, the wind-powered soil treatment is feasible, obtaining a 53.9% removal of 2,4-D after 15 days treatment. Nevertheless, the remediation is more efficient if it is fed by a constant electric input (conventional DC power supply), reaching a 90.2% removal of 2,4-D with a much lower amount of charge supplied (49.2 A h kg(-1) and 4.33 A h kg(-1) for wind-powered and conventional) within the same operation time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Research of combined adsorption-coagulation process in treating petroleum refinery effluent.

PubMed

Wang, Bing; Shui, Yiyu; Ren, Hongyang; He, Min

2017-02-01

The petroleum refinery industry generates a significant amount of wastewater that contains a high level of organic matter, which calls for effective and costly treatments. In this research, the effectiveness of the petroleum refinery effluent (PRE) treatment with physicochemical process of combined adsorption and coagulation was evaluated. The effects of initial pH, hydraulic condition , and combined sequence of treatment process, different treating reagent types and dosages on the chemical oxygen demand (COD) removal were investigated. Additionally, the elimination efficiency of pollutant wastewater was monitored by gas chromatography-mass spectrometry (GC-MS), and Fourier transformed infrared (FT-IR) spectrophotometer was adopted to describe the structure of the wastewater. Wooden activated carbon was chosen as adsorbent at the dosage of 10 g/L as a primary treatment, and 1500 mg/L polymeric magnesium ferric sulfate was used in coagulation. Results showed that adsorption and subsequent coagulation displayed the best performance when initial pH was 9 at shear rates (G) of G1 = 65 s -1 and G2 = 20 s -1 , which reached maximal removal rate of COD and total organic carbon GC-MS testing result revealed that adsorption was effective in phenols and iso-alkanes removal, whereas coagulation was good at removing esters and n-alkanes.

Da-KGM based GO-reinforced FMBO-loaded aerogels for efficient arsenic removal in aqueous solution.

PubMed

Ye, Shuxin; Jin, Weiping; Huang, Qing; Hu, Ying; Li, Yan; Li, Jing; Li, Bin

2017-01-01

Composites based on deacetylated konjac glucomannan (Da-KGM) and graphene oxide (GO) aerogels with iron and manganese oxides (FMBO) for effective removal of arsenic from contaminated water. Da-KGM, which was used as supporting composite matrix here, were firstly treated with GO and loaded FMBO. The obtained Da-KGM/GO/FMBO composite aerogels were characterized by compression test, thermo gravimetric analysis (TGA), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The characteristic results showed that addition of GO exhibited enhanced mechanical properties towards Da-KGM aerogels. What's more, results of FTIR indicated the strong intermolecular hydrogen bond interaction between KGM and GO. Batch adsorption tests were used to evaluate arsenic removal capacity. Da-KGM/GO loaded FMBO composite aerogels exhibited high adsorption ability for arsenite [As(III)] and arsenate [As(V)]. The adsorption results showed that the arsenic for both arsenite [As(III)] and arsenate [As(V)] removal process followed a pseudo-second-order rate equation and Langmuir monolayer adsorption. The maximum As(III) and As(V) uptake capacity of Da-KGM/GO(10%)/FMBO composite aerogels reached 30.21mgg -1 and 12.08mgg -1 respectively according to Langmuir isotherm at pH 7 and 323K. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative research on phosphorus removal by pilot-scale vertical flow constructed wetlands using steel slag and modified steel slag as substrates.

PubMed

Yun, Yupan; Zhou, Xiaoqin; Li, Zifu; Uddin, Sayed Mohammad Nazim; Bai, Xiaofeng

2015-01-01

This research mainly focused on the phosphorus removal performance of pilot-scale vertical flow constructed wetlands with steel slag (SS) and modified steel slag (MSS). First, bench-scale experiments were conducted to evaluate the phosphorus adsorption capacity. Results showed that the Langmuir model could better describe the adsorption characteristics of the two materials; the maximum adsorption of MSS reached 12.7 mg/g, increasing by 34% compared to SS (9.5 mg/g). Moreover, pilot-scale constructed wetlands with SS and MSS were set up outdoors. Then, the influence of hydraulic retention time (HRT) and phosphorus concentration in phosphorus removal for two wetlands were investigated. Results revealed that better performance of the two systems could be achieved with an HRT of 2 d and phosphorus concentration in the range of 3-4.5 mg/L; the system with MSS had a better removal efficiency than the one with SS in the same control operation. Finally, the study implied that MSS could be used as a promising substrate for wetlands to treat wastewater with a high phosphorus concentration. However, considering energy consumption, SS could be regarded as a better alternative for substrate when treating sewage with a low phosphorus concentration.

Removal of fluoride, SDS, ammonia and turbidity from semiconductor wastewater by combined electrocoagulation-electroflotation.

PubMed

Aoudj, S; Khelifa, A; Drouiche, N

2017-08-01

Semiconductor industry effluents contain organic and inorganic pollutants, such as sodium dodecyl sulfate (SDS), fluoride and ammonia, at high levels which consists a major environmental issue. A combined EC-EF process is proposed as a post-treatment after precipitation for simultaneous clarification and removal of pollutants. In EC step, a hybrid Fe-Al was used as the soluble anode in order to avoid supplementary EC step. EC-Fe is more suitable for SDS removal; EC-Al is more suitable for fluoride removal, while EC with hybrid Al-Fe makes a good compromise. Clarification and ammonia oxidation were achieved in the EF step. Effects of anodic material, initial pH, current, anion nature, chloride concentration and initial pollutant concentration were studied. The final concentrations may reach 0.27, 6.23 and 0.22 mg L -1 for SDS, fluoride and ammonia respectively. These concentrations are far lower than the correspondent discharge limits. Similarly, the final turbidity was found 4.35 NTU which is lower than 5NTU and the treated water does not need further filtration before discharge. Furthermore, the EC-EF process proves to be sufficiently energy-efficient with less soluble electrode consumption. Copyright © 2017 Elsevier Ltd. All rights reserved.

The influence of small-scale interlayer heterogeneity on DDT removal efficiency for flushing technology.

PubMed

Wang, Xingwei; Chen, Jiajun

2017-06-01

With an aim to investigate the influence of small-scale interlayer heterogeneity on DDT removal efficiency, batch test including surfactant-stabilized foam flushing and solution flushing were carried out. Two man-made heterogeneous patterns consisting of coarse and fine quartz sand were designed to reveal the influencing mechanism. Moreover, the removal mechanism and the corresponding contribution by foam flushing were quantitatively studied. Compared with surfactant solution flushing, the DDT removal efficiency by surfactant-stabilized foam flushing increased by 9.47% and 11.28% under heterogeneous patterns 1 and 2, respectively. The DDT removal contributions of improving sweep efficiency for heterogeneous patterns 1 and 2 by foam flushing were 40.82% and 45.98%, and the contribution of dissolving capacity were 59.18% and 54.02%, respectively. The dissolving capacity of DDT played a major role in DDT removal efficiency by foam flushing under laboratory conditions. And the DDT removal contribution of significant improving sweep efficiency was higher than that of removal decline caused by weak solubilizing ability of foam film compared with solution flushing. The obtained results indicated that the difference of DDT removal efficiency by foam flushing was decreased under two different heterogeneous patterns with the increase of the contribution of improving foam flushing sweep efficiency. It suggested that foam flushing can reduce the disturbance from interlayer heterogeneity in remediating DDT contaminated heterogeneous medium. Copyright © 2017 Elsevier B.V. All rights reserved.

Nitrogen retention in rivers: Model development and application to watersheds in the northeastern U.S.A.

USGS Publications Warehouse

Seitzinger, S.P.; Styles, R.V.; Boyer, E.W.; Alexander, R.B.; Billen, G.; Howarth, R.W.; Mayer, B.; Van Breemen, N.

2002-01-01

A regression model (RivR-N) was developed that predicts the proportion of N removed from streams and reservoirs as an inverse function of the water displacement time of the water body (ratio of water body depth to water time of travel). When applied to 16 drainage networks in the eastern U.S., the RivR-N model predicted that 37% to 76% of N input to these rivers is removed during transport through the river networks. Approximately half of that is removed in 1st through 4th order streams which account for 90% of the total stream length. The other half is removed in 5th order and higher rivers which account for only about 10% of the total stream length. Most N removed in these higher orders is predicted to originate from watershed loading to small and intermediate sized streams. The proportion of N removed from all streams in the watersheds (37-76%) is considerably higher than the proportion of N input to an individual reach that is removed in that reach (generally <20%) because of the cumulative effect of continued nitrogen removal along the entire flow path in downstream reaches. This generally has not been recognized in previous studies, but is critical to an evaluation of the total amount of N removed within a river network. At the river network scale, reservoirs were predicted to have a minimal effect on N removal. A fairly modest decrease (<10 percentage points) in the N removed at the river network scale was predicted when a third of the direct watershed loading was to the two highest orders compared to a uniform loading.

Modeling nutrient retention at the watershed scale: Does small stream research apply to the whole river network?

NASA Astrophysics Data System (ADS)

Aguilera, Rosana; Marcé, Rafael; Sabater, Sergi

2013-06-01

are conveyed from terrestrial and upstream sources through drainage networks. Streams and rivers contribute to regulate the material exported downstream by means of transformation, storage, and removal of nutrients. It has been recently suggested that the efficiency of process rates relative to available nutrient concentration in streams eventually declines, following an efficiency loss (EL) dynamics. However, most of these predictions are based at the reach scale in pristine streams, failing to describe the role of entire river networks. Models provide the means to study nutrient cycling from the stream network perspective via upscaling to the watershed the key mechanisms occurring at the reach scale. We applied a hybrid process-based and statistical model (SPARROW, Spatially Referenced Regression on Watershed Attributes) as a heuristic approach to describe in-stream nutrient processes in a highly impaired, high stream order watershed (the Llobregat River Basin, NE Spain). The in-stream decay specifications of the model were modified to include a partial saturation effect in uptake efficiency (expressed as a power law) and better capture biological nutrient retention in river systems under high anthropogenic stress. The stream decay coefficients were statistically significant in both nitrate and phosphate models, indicating the potential role of in-stream processing in limiting nutrient export. However, the EL concept did not reliably describe the patterns of nutrient uptake efficiency for the concentration gradient and streamflow values found in the Llobregat River basin, posing in doubt its complete applicability to explain nutrient retention processes in stream networks comprising highly impaired rivers.

Floral function: effects of traits on pollinators, male and female pollination success, and female fitness across three species of milkweeds (Asclepias).

PubMed

La Rosa, Raffica J; Conner, Jeffrey K

2017-01-01

Central questions in plant reproductive ecology are whether the functions of floral traits in hermaphrodites create conflict between sexes that could slow evolution, and whether individual floral traits function in pollinator attraction, efficiency, or both. We studied how floral traits affect pollinator visitation and efficiency, and how they affect male and female function and female fitness within and across three Asclepias species that differ in floral morphology. Using separate multiple regressions, we regressed pollen removal, deposition, and fruit number onto six floral traits. We also used path analyses integrating these variables with pollinator visitation data for two of the species to further explore floral function and its effects on fruit production. Most traits affected male pollination success only, and these effects often differed between species. The exception was increased slit length, which increased pollinia insertion in two of the species. There were no interspecific differences in the effects of the traits on female pollination success. All traits except horn reach affected pollination efficiency in at least one species, and horn reach and two hood dimensions were the only traits to affect pollinator attraction, but in just one species. Traits tended to function in only one sex, and more traits affected function through pollinator efficiency than through attraction. There was no significant link between female pollination success and female fitness in any of the three species; this pattern is consistent with fruit production not being limited by pollen deposition. © 2017 Botanical Society of America.

Adsorption of SO2 and NO from incineration flue gas onto activated carbon fibers.

PubMed

Liu, Zhen-Shu

2008-11-01

Activated carbon fibers (ACFs) were used to remove SO2 and NO from incineration flue gas. Three types of ACFs in their origin state and after pretreatment with HNO3, NaOH, and KOH were investigated. The removal efficiencies of SO2 and NO were determined experimentally at defined SO2 and NO concentrations and at temperatures of 150, 200 and 260 degrees C. Experimental results indicated that the removal efficiencies of SO2 and NO using the original ACFs were < 56% and < 27%, respectively. All ACFs modified with HNO3, NaOH, and KOH solution could increase the removal efficiencies of SO(2) and NO. The mesopore volumes and functional groups of ACFs are important in determining the removal of SO2 and NO. When the mesopore volumes of the ACFs are insufficient for removing SO2 and NO, the functional groups on the ACFs are not important in determining the removal of SO2 and NO. On the contrary, the effects of the functional groups on the removal of SO2 and NO are more important than the mesopore volumes as the amount of mesopores on the ACFs is sufficient to remove SO2 and NO. Moreover, the removal efficiencies of SO2 and NO were greatest at 200 degrees C. When the inlet concentration of SO2 increased to 600 ppm, the removal efficiency of SO2 increased slightly and the removal efficiency of NO decreased.

Does the combination of biochar and clinoptilolite enhance nutrient recovery from the liquid fraction of biogas digestate?

PubMed

Kocatürk-Schumacher, Nazlı Pelin; Zwart, Kor; Bruun, Sander; Brussaard, Lijbert; Jensen, Lars Stoumann

2017-05-01

Concentrating nutrients on biochar and clinoptilolite and subsequently using the nutrient-enriched sorbents as a fertiliser could be an alternative way to manage nutrients in digestate. In this study, we investigated the use of biochar and clinoptilolite columns in removing ammonium, potassium, orthophosphate and dissolved organic carbon (DOC) from the liquid fraction of digestate. Our objectives were to investigate the effect of the initial loading ratio between liquid and biochar on nutrient removal, and to investigate the effect of combining biochar with clinoptilolite on nutrient and DOC removal efficiency. Increasing the initial loading ratios increased nutrient concentrations on biochar to 8.61 mg NH 4 -N g -1 , 1.95 mg PO 4 -P g -1 and 13.01 mg DOC g -1 , but resulted in decreasing removal efficiencies. The combination of biochar and clinoptilolite resulted in improved ammonium, potassium and DOC removal efficiencies compared to biochar alone, but did not significantly change PO 4 -P removal efficiencies. Removal efficiencies with combined sorbents were up to 67% for ammonium, 58% for DOC and 58% for potassium. Clinoptilolite showed higher removal efficiencies compared to biochar alone, and combining clinoptilolite with biochar improved only total P removal efficiency. Concentrating nutrients with clinoptilolite and biochar may be an option when both sorbents are available at low cost.

Catalytic removal of phenol from gas streams by perovskite-type catalysts.

PubMed

Chen, Dai Ling; Pan, Kuan Lun; Chang, Moo Been

2017-06-01

Three perovskite-type catalysts prepared by citric acid method are applied to remove phenol from gas streams with the total flow rate of 300mL/min, corresponding to a GHSV of 10,000/hr. LaMnO 3 catalyst is first prepared and further partially substituted with Sr and Cu to prepare La 0.8 Sr 0.2 MnO 3 and La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 , and catalytic activities and fundamental characteristics of these three catalysts are compared. The results show that phenol removal efficiency achieved with La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 reaches 100% with the operating temperature of 200°C and the rate of mineralization at 300°C is up to 100%, while the phenol removal efficiencies achieved with La 0.8 Sr 0.2 MnO 3 and LaMnO 3 are up to 100% with the operating temperature of 300°C and 400°C, respectively. X-ray photoelectron spectroscopy (XPS) analysis shows that the addition of Sr and Cu increases the lattice oxygen of La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 , and further increases mobility or availability of lattice oxygen. The results indicate that La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 has the best activity for phenol removal among three catalysts prepared and the catalytic activity of phenol oxidation is enhanced by the introduction of Sr and Cu into LaMnO 3 . Apparent activation energy of 48kJ/mol is calculated by Mars-Van Krevelen Model for phenol oxidation with La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 as catalyst. Copyright © 2016. Published by Elsevier B.V.

Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons.

PubMed

Hajizadeh, Yaghoub; Onwudili, Jude A; Williams, Paul T

2011-06-01

The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275°C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 μg I-TEQ kg(-1) toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 μg I-TEQ kg(-1) in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases. Copyright © 2011 Elsevier Ltd. All rights reserved.

40 CFR 63.4566 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2011 CFR

2011-07-01

... device emission destruction or removal efficiency? 63.4566 Section 63.4566 Protection of Environment... efficiency? You must use the procedures and test methods in this section to determine the add-on control device emission destruction or removal efficiency as part of the performance test required by § 63.4560...

40 CFR 63.4566 - How do I determine the add-on control device emission destruction or removal efficiency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... device emission destruction or removal efficiency? 63.4566 Section 63.4566 Protection of Environment... efficiency? You must use the procedures and test methods in this section to determine the add-on control device emission destruction or removal efficiency as part of the performance test required by § 63.4560...

Deep Kalman Filter: Simultaneous Multi-Sensor Integration and Modelling; A GNSS/IMU Case Study

PubMed Central

Hosseinyalamdary, Siavash

2018-01-01

Bayes filters, such as the Kalman and particle filters, have been used in sensor fusion to integrate two sources of information and obtain the best estimate of unknowns. The efficient integration of multiple sensors requires deep knowledge of their error sources. Some sensors, such as Inertial Measurement Unit (IMU), have complicated error sources. Therefore, IMU error modelling and the efficient integration of IMU and Global Navigation Satellite System (GNSS) observations has remained a challenge. In this paper, we developed deep Kalman filter to model and remove IMU errors and, consequently, improve the accuracy of IMU positioning. To achieve this, we added a modelling step to the prediction and update steps of the Kalman filter, so that the IMU error model is learned during integration. The results showed our deep Kalman filter outperformed the conventional Kalman filter and reached a higher level of accuracy. PMID:29695119

Leanergy(TM): how lean manufacturing can improve energy efficiency.

PubMed

Riche, Jean-Pierre

2013-01-01

Energy efficiency has become a competitive issue for industrial companies. The evolution of energy prices and regulation will make this issue even more important in the future. For several years, the energy-intensive chemical industry has been implementing corrective actions. Helped by the absorption of base load energy consumption by larger production volumes, specific energy consumption (KWh per production unit) has been significantly reduced in recent years. However, most plants have reached the end of their first action plan based on improving the utilities performance. The Leanergy(TM) method developed by the consultancy company Okavango-energy, is a structured approach based on lean manufacturing which widens the scope of saving sources to process and operations. Starting from the analysis of actual production requirements, Okavango is able to adjust consumption to minimum requirements and so remove any energy consumption that does not contribute to the added value creation.

Effect of combined ecological floating bed for eutrophic lake remediation

NASA Astrophysics Data System (ADS)

Zheng, Liguo; Wang, Haiping

2017-05-01

A novel combined ecological floating bed(CEFB) integrated high-density hydrophyte and aquatic animals, the wave-making equipments, water cycling automatic aerators and fluorescence inducing equipments. The water quality of a eutrophic lake was improved significantly after three months remediation of CEFB. Compared with the background value, the results showed that the removal efficiencies of total nitrogen (TN), ammonia(NH3-N), total phosphorous(TP) and chemical oxygen demand (COD) in the water reached 31.5%, 33%, 30.5% and 53%, respectively. CEFB could manipulate biotic interactions in the aquatic ecosystem, and then absorb eutrophic material efficiently by the co-effect of floating the sediment slowly, refreshing the static eutrophic water body, changing the photosynthetic and biochemical environment of the eutrophic water body and inducing plankton directional movement. At the same time, plants and fish grew good in CEFB,which can bring economic income to some extent.

Deep Kalman Filter: Simultaneous Multi-Sensor Integration and Modelling; A GNSS/IMU Case Study.

PubMed

Hosseinyalamdary, Siavash

2018-04-24

Bayes filters, such as the Kalman and particle filters, have been used in sensor fusion to integrate two sources of information and obtain the best estimate of unknowns. The efficient integration of multiple sensors requires deep knowledge of their error sources. Some sensors, such as Inertial Measurement Unit (IMU), have complicated error sources. Therefore, IMU error modelling and the efficient integration of IMU and Global Navigation Satellite System (GNSS) observations has remained a challenge. In this paper, we developed deep Kalman filter to model and remove IMU errors and, consequently, improve the accuracy of IMU positioning. To achieve this, we added a modelling step to the prediction and update steps of the Kalman filter, so that the IMU error model is learned during integration. The results showed our deep Kalman filter outperformed the conventional Kalman filter and reached a higher level of accuracy.

Addition of anaerobic tanks to an oxidation ditch system to enhance removal of phosphorus from wastewater.

PubMed

Liu, Jun-xin; van Groenestijn, J W; Doddema, H J; Wang, Bao-zhen

2002-04-01

The oxidation ditch has been used for many years all over the world as an economic and efficient wastewater treatment technology. It can remove COD, nitrogen and a part of phosphorus efficiently. In the experiment described, a pilot scale Pasveer oxidation ditch system has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that influent total phosphorus(TP) was removed for 35%-50%. After this, two anaerobic tanks with total volume of 11 m3 were added to the system to release phosphorus. As a result, the TP removal efficiency increased by about 20%. At an anaerobic HRT of about 6 hours, a TP removal efficiency of 71% was achieved.

Efficiency of removal of cadmium from aqueous solutions by plant leaves and the effects of interaction of combinations of leaves on their removal efficiency.

PubMed

Salim, R; Al-Subu, M; Dawod, E

2008-05-01

Removal of cadmium from aqueous solutions using 20 species of plant leaves and combinations of these leaves have been studied. Several factors affecting the removal efficiency have been studied. The most efficient types of plant leaves for the removal of cadmium are those of styrax, plum, pomegranate and walnut. The interaction effect of the combined leaf samples on the efficiency of removal of cadmium has been found to be additive in combinations involving styrax plant leaves but seems to be antagonistic in all other combinations. The optimum experimental conditions for removal of cadmium have been found to be at pH 4.1, using high concentrations of naturally dried plant leaves, using ground leaves and to remove cadmium from agitated aqueous solutions. The percentage of metal removed at an initial cadmium concentration of 10mg/l by the most efficient types of leaves have been found to be 85% for styrax leaves, 85% for plum leaves, 80% for pomegranate leaves, 78% for walnut leaves and 77% for meddler leaves. The presence of foreign ions or complexing agents has been found to reduce the efficiency of removal of cadmium by plant leaves. About 80-85% of the cadmium in charged plant leaves has been released under the influence of changing the pH of the solution, addition of competing ions and the addition of EDTA. The results of removal of cadmium by plant leaves have been found to follow the Freundlich adsorption isotherm, first-order reaction with respect to cadmium and to have intra-pore diffusion as the rate-limiting step.

Monitoring of electrokinetic removal of heavy metals in tailing-soils using sequential extraction analysis.

PubMed

Kim, S O; Kim, K W

2001-08-17

This research focused on the monitoring of the electrokinetic removal of heavy metals from tailing-soils, and emphasizes the dependency of removal efficiencies upon their physico-chemical states, as demonstrated by the different extraction methods adopted, which included aqua regia and sequential extraction. The tailing-soils examined contained high concentrations of target metal contaminants (Cd=179mgkg(-1), Cu=207mgkg(-1), Pb=5175mgkg(-1), and Zn=7600mgkg(-1)). The removal efficiencies of the different metals were significantly influenced by their speciations, mobilities and affinities (adsorption capacities) in the soil matrix. The removal efficiencies of mobile and weakly bound fractions, such as the exchangeable fraction were more than 90% by electrokinetic treatment, but strongly bound fractions, such as the organically bound species and residual fraction were not significantly removed (less than 30% removal efficiencies). In accordance with the general sequence of mobilities of heavy metals in soils, the removal efficiencies of more mobile heavy metals (Cd, Cu, and Zn) were higher than that of less mobile heavy metal (Pb).

Synthesis and Characterization of Modified BiOCl and Their Application in Adsorption of Low-Concentration Dyes from Aqueous Solution

NASA Astrophysics Data System (ADS)

Zhao, Qihang; Xing, Yongxing; Liu, Zhiliang; Ouyang, Jing; Du, Chunfang

2018-03-01

The synthesis and characterization of BiOCl and Fe3+-grafted BiOCl (Fe/BiOCl) is reported that are developed as efficient adsorbents for the removal of cationic dyes rhodamine B (RhB) and methylene blue (MB) as well as anionic dyes methyl orange (MO) and acid orange (AO) from aqueous solutions with low concentration of 0.01 0.04 mmol/L. Characterizations by various techniques indicate that Fe3+ grafting induced more open porous structure and higher specific surface area. Both BiOCl and Fe/BiOCl with negatively charged surfaces showed excellent adsorption efficiency toward cationic dyes, which could sharply reach 99.6 and nearly 100% within 3 min on BiOCl and 97.0 and 98.0% within 10 min on Fe/BiOCl for removing RhB and MB, respectively. However, Fe/BiOCl showed higher adsorption capacity than BiOCl toward ionic dyes. The influence of initial dye concentration, temperature, and pH value on the adsorption capacity is comprehensively studied. The adsorption process of RhB conforms to Langmuir adsorption isotherm and pseudo-second-order kinetic feature. The excellent adsorption capacities of as-prepared adsorbents toward cationic dyes are rationalized on the basis of electrostatic attraction as well as open porous structure and high specific surface area. In comparison with Fe/BiOCl, BiOCl displays higher selective efficiency toward cationic dyes in mixed dye solutions.

Improving the sweeping efficiency of permanganate into low permeable zones to treat TCE: experimental results and model development.

PubMed

Chokejaroenrat, Chanat; Kananizadeh, Negin; Sakulthaew, Chainarong; Comfort, Steve; Li, Yusong

2013-11-19

The residual buildup and treatment of dissolved contaminants in low permeable zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate into LPZs to treat dissolved-phase TCE. This was accomplished by conducting transport experiments that quantified the ability of xanthan-MnO4(-) solutions to penetrate and cover (i.e., sweep) an LPZ that was surrounded by transmissive sands. By incorporating the non-Newtonian fluid xanthan with MnO4(-), penetration of MnO4(-) into the LPZ improved dramatically and sweeping efficiency reached 100% in fewer pore volumes. To quantify how xanthan improved TCE removal, we spiked the LPZ and surrounding sands with (14)C-lableled TCE and used a multistep flooding procedure that quantified the mass of (14)C-TCE oxidized and bypassed during treatment. Results showed that TCE mass removal was 1.4 times greater in experiments where xanthan was employed. Combining xanthan with MnO4(-) also reduced the mass of TCE in the LPZ that was potentially available for rebound. By coupling a multiple species reactive transport model with the Brinkman equation for non-Newtonian flow, the simulated amount of (14)C-TCE oxidized during transport matched experimental results. These observations support the use of xanthan as a means of enhancing MnO4(-) delivery into LPZs for the treatment of dissolved-phase TCE.

Wastewater treatment for nutrient removal with Ecuadorian native microalgae.

PubMed

Benítez, María Belén; Champagne, Pascale; Ramos, Ana; Torres, Andres F; Ochoa-Herrera, Valeria

2018-04-12

The aim of this project was to study the feasibility of utilizing native microalgae for the removal of nitrogen and phosphorus, as a potential secondary wastewater treatment process in Ecuador. Agitation and aeration batch experiments were conducted using synthetic secondary wastewater effluent, to determine nitrogen and phosphorus removal efficiencies by a native Ecuadorian microalgal strain. Experimental results indicated that microalgal cultures could successfully remove nitrogen and phosphorus. [Formula: see text] and [Formula: see text] removal efficiencies of 52.6 and 55.6%, and 67.0 and 20.4%, as well as [Formula: see text] production efficiencies of 87.0 and 93.1% were reported in agitation and aeration photobioreactors, respectively. Aeration was not found to increase the nutrient removal efficiency of [Formula: see text]. Moreover, in the case of [Formula: see text], a negative impact was observed, where removal efficiencies decreased by a factor of 3.3 at higher aeration rates. To the best of our knowledge, this is the first report of the removal of nutrients by native Ecuadorian Chlorella sp., hence the results of this study would indicate that this native microalgal strain could be successfully incorporated in a potential treatment process for nutrient removal in Ecuador.

Degradation of pyridine and quinoline in aqueous solution by gamma radiation

NASA Astrophysics Data System (ADS)

Chu, Libing; Yu, Shaoqing; Wang, Jianlong

2018-03-01

In present work, the degradation of two N-heteroaromatic pollutants, i.e., pyridine and quinoline was investigated by gamma irradiation in the presence of TiO2 nanoparticle. The experimental results showed that quinoline has a higher degradation rate than pyridine. The removal efficiency of the pollutants, TOC and TN reached 93.0%, 11.9% and 12.0% for quinoline, 71.0%, 10.6% and 4.4% for pyridine, respectively at 7.0 kGy and initial concentration of 50 mg/L. Ammonium was detected for both pyridine and quinoline within the absorbed doses, suggesting that the organic nitrogen was transformed into ammonium. The degradation rate constant of pyridine and quinoline was increased by 1.1-1.5 times with addition of TiO2. TiO2 nanoparticles were especially effective to enhance the mineralization. The removal efficiency of TOC and TN was increased by 15-12% for pyridine and 23-25% for quinoline, respectively in the presence of 2.0 g/L TiO2. Following gamma irradiation, 2-hydroxypyridine, 3-hydroxypyridine, oxalic acid and formic acid were identified for pyridine and the hydroxyl quinoline and formic acid were detected for quinoline. Accordingly, the degradation mechanism of pyridine and quinoline by gamma irradiation was tentatively proposed.

Green synthesis of tannin-hexamethylendiamine based adsorbents for efficient removal of Cr(VI).

PubMed

Liu, Qiang; Liu, Qinze; Liu, Bingsi; Hu, Tao; Liu, Weiliang; Yao, Jinshui

2018-06-15

Newly developed adsorbents, poly(tannin-hexamethylendiamine) (PTHA), were fabricated by varying the mole ratio of tannin (TA) and hexamethylendiamine (HA) under one-pot reaction. The specific forming process of the adsorbent which had undergone the transition from hydrogen bonds to covalent bonds was subsequently explored. Based on the efficiency of Cr(VI) removal from aqueous solution over all prepared adsorbents, the PTHA-4 (mole ratio of TA/HA = 1:12.5) exhibited an excellent adsorption behavior. Adsorption experiments affected by contact time and ionic strength have been conducted successively by PTHA-4, and the equilibrium was reached at 24 h. The kinetic data revealed that the adsorption was good agreement with pseudo-second order model and needed to undergo the rate-controlling step. The maximum adsorption capacity was 283.29 mg/g at 30 °C, relying on the isothermal curve suitably described by Langmuir model. Furthermore, toxic Cr(VI) had been reduced to the low toxic Cr(III) during adsorption process. The structures and adsorption performance of adsorbent were confirmed by means of SEM, FT-IR, XPS etc. Thus, the cheap-sustainable adsorbents have a superior feature for Cr(VI)-wastewater purification in future. Copyright © 2018 Elsevier B.V. All rights reserved.

An overview of advanced reduction processes for bromate removal from drinking water: Reducing agents, activation methods, applications and mechanisms.

PubMed

Xiao, Qian; Yu, Shuili; Li, Lei; Wang, Ting; Liao, Xinlei; Ye, Yubing

2017-02-15

Bromate (BrO 3 - ) is a possible human carcinogen regulated at a strict standard of 10μg/L in drinking water. Various techniques to eliminate BrO 3 - usually fall into three main categories: reducing bromide (Br - ) prior to formation of BrO 3 - , minimizing BrO 3 - formation during the ozonation process, and removing BrO 3 - from post-ozonation waters. However, the first two approaches exhibit low degradation efficiency and high treatment cost. The third workaround has obvious advantages, such as high reduction efficiency, more stable performance and easier combination with UV disinfection, and has therefore been widely implemented in water treatment. Recently, advanced reduction processes (ARPs), the photocatalysis of BrO 3 - , have attracted much attention due to improved performance. To increase the feasibility of photocatalytic systems, the focus of this work concerns new technological developments, followed by a summary of reducing agents, activation methods, operational parameters, and applications. The reaction mechanisms of two typical processes involving UV/sulfite homogeneous photocatalysis and UV/titanium dioxide heterogeneous photocatalysis are further summarized. The future research needs for ARPs to reach full-scale potential in drinking water treatment are suggested accordingly. Copyright © 2016. Published by Elsevier B.V.

An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater.

PubMed

Li, Yajie; Tabassum, Salma; Zhang, Zhenjia

2016-09-01

An advanced anaerobic biofilter (AF) was introduced for the treatment of coal gasification wastewater (CGW), and effluent recirculation was adopted to enhance phenol removal and methane production. The results indicated that AF was reliable in treating diluted CGW, while its efficiency and stability were seriously reduced when directly treating raw CGW. However, its performance could be greatly enhanced by effluent recirculation. Under optimal effluent recirculation of 0.5 to the influent, concentrations of chemical oxygen demand (COD) and total phenol in the effluent could reach as low as 234.0 and 14.2mg/L, respectively. Also, the rate of methane production reached 169.0mLCH4/L/day. Though CGW seemed to restrain the growth of anaerobic microorganisms, especially methanogens, the inhibition was temporary and reversible, and anaerobic bacteria presented strong tolerance. The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater (GW). However, the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication. By analysis using the Haldane model, it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters, but only suitable effluent recirculation could result in high methanogenic activity. Copyright © 2016. Published by Elsevier B.V.

Isolation of Lactobacillus sakei strain KJ-2008 and its removal of characteristic malodorous gases under anaerobic culture conditions.

PubMed

Kim, Jeong-Dong; Kang, Kook-Hee

2004-12-01

A number of different sources, such as composts, leachates, and pig feces samples were collected from different pig farms in Korea. Several microorganisms were screened for their ability to deodorize the malodorous gases. As a result, a novel malodorous gas-deodorizing bacterial strain KJ-2008 was isolated due to the most abundant of nitrate-supplemented minimal media under anaerobic conditions. Crimp-sealed serum bottles containing nitrate-supplemented minimal medium (MM-NO(3)(-)) in airtight conditions were inoculated with KJ-2008. Nitrate concentration decreased rapidly after 20 h incubation and nitrite production reached almost zero during the time the experimental was carried out. Taxonomic identification including 16S rDNA base sequencing and phylogenetic analysis indicated that the isolate KJ-2008 had a 99.8% homology in its 16S rDNA base sequence with Lactobacillus sakei. Among the volatile fatty acids, acetic acid contained in large amounts in fresh piggery slurry decreased about 40% after 50 h incubation of the strain KJ-2008. n-Butyric acid, n-valeric acid, and iso-valeric acid gradually decreased, and iso-butyric acid and capronic acid dramatically eliminated at initial time with the treatment. Moreover, NH(3) removal efficiency reached a maximum of 98.5% after 50 h of incubation. The concentration of H(2)S did not change.

Opportunities for Phytoremediation and Bioindication of Arsenic Contaminated Water Using a Submerged Aquatic Plant:Vallisneria natans (lour.) Hara.

PubMed

Chen, Guoliang; Liu, Xingmei; Brookes, Philip C; Xu, Jianming

2015-01-01

The identification of plants with high arsenic hyperaccumulating efficiency from water is required to ensure the successful application of phytoremediation technology. Five dominant submerged plant species (Vallisneria natans (Lour.) Hara., Potamageton crispus L., Myriophyllum spicatum L., Ceratophyllum demersum L. and Hydrilla verticillata (L.f.) Royle) in China were used to determine their potential to remove As from contaminated water. V. natans had the highest accumulation of As among them. The characteristics of As accumulation, transformation and the effect of phosphate on As accumulation in V. natans were then further studied. The growth of V. natans was not inhibited even when the As concentration reached 2.0 mg L(-1). After 21 d of As treatment, the bioconcentration factor (BCF) reached 1300. The As concentration in the environment and exposure time are major factors controlling the As concentration in V. natans. After being absorbed, As(V) is efficiently reduced to As(III) in plants. The synthesis of non-enzymic antioxidants may play an important role under As stress and increase As detoxication. In addition, As(V) uptake by V. natans was negatively correlated with phosphate (P) uptake when P was sufficiently supplied. As(V) is probably taken up via P transporters in V. natans.

Removal of inhibitors from lignocellulosic hydrolyzates by vacuum membrane distillation.

PubMed

Chen, Jingwen; Zhang, Yaqin; Wang, Yafei; Ji, Xiaosheng; Zhang, Lin; Mi, Xigeng; Huang, He

2013-09-01

In this study, vacuum membrane distillation (VMD) was used to remove two prototypical fermentation inhibitors (acetic acid and furfural) from lignocellulose hydrolyzates. The effect of operating parameters, such as feed temperature and feed velocity, on the removal efficiencies of inhibitors was investigated. Under optimal conditions, more than 98% of furfural could be removed by VMD. However, the removal efficiency of acetic acid was considerably lower. After furfural and acetic acid were selectively removed from hydrolyzates by VMD, ethanol production efficiency increased by 17.8% compared to original hydrolyzates. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study on removal efficiency of nitrogen and phosphorus from agricultural wastewater by subsurface flow constructed wetland

NASA Astrophysics Data System (ADS)

Ling, Zhen; Li, Jie

2018-03-01

Subsurface Flow Constructed Wetland Plant 5 kinds of perennial herbs, there are Canna, Water onion, Iris, Calamus, Reed. Foucs on Subsurface Flow Constructed Wetlands on agricultural wastewater nitrogen and phosphorus removal effect. Research results: Different plants TP removal efficiency from high to low is Iris> reed> calamus> water onion> canna.And TN removal efficiency from high to low is reed> water onion> iris> calamus> canna. Compared with the blank test land, Wetland plants improves TN removal and TP removal is higher than TN. Wetland plants can reduce the PH of experimental water.

Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates.

PubMed

Zhang, Dong Qing; Gersberg, Richard M; Hua, Tao; Zhu, Junfei; Tuan, Nguyen Anh; Tan, Soon Keat

2012-04-01

Determining the fate of emerging organic contaminants in an aquatic ecosystem is important for developing constructed wetlands (CWs) treatment technology. Experiments were carried out in subsurface flow CWs in Singapore to evaluate the fate and transport of eight pharmaceutical compounds. The CW system included three parallel horizontal subsurface flow CWs and three parallel unplanted beds fed continuously with synthetic wastewater at different hydraulic retention times (HRTs). The findings of the tests at 2-6 d HRTs showed that the pharmaceuticals could be categorized as (i) efficiently removed compounds with removal higher than 85% (ketoprofen and salicylic acid); (ii) moderately removed compounds with removal efficiencies between 50% and 85% (naproxen, ibuprofen and caffeine); and (iii) poorly removed compounds with efficiency rate lower than 50% (carbamazepine, diclofenac, and clofibric acid). Except for carbamazepine and salicylic acid, removal efficiencies of the selected pharmaceuticals showed significant (p<0.05) enhancement in planted beds as compared to the unplanted beds. Removal of caffeine, ketoprofen and clofibric acid were found to follow first order decay kinetics with decay constants higher in the planted beds than the unplanted beds. Correlations between pharmaceutical removal efficiencies and log K(ow) were not significant (p>0.05), implying that their removal is not well related to the compound's hydrophobicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Treatment of laundrette wastewater using Starbon and Fenton's reagent.

PubMed

Tony, Maha A; Parker, Helen L; Clark, James H

2016-09-18

The use of grey water for a variety of purposes is gaining increased popularity as a means of preserving scarce freshwater resources. In this work, catalytic oxidation over Fenton's reagent and adsorption techniques using Starbon (mesoporous material derived from polysaccharides) has been applied. These novel techniques are used as an alternative to already studied treatments of grey water such as filtration and/or biological processes. In this study, grey water, collected from a commercial laundrette, has been used. Treatment efficiency was determined by changes in the chemical oxygen demand (COD) of the grey water. Experiments using Fenton's reagent at optimum conditions of Fe(3+) = 40 mg L(-1); H2O2 = 400 mg L(-1) and pH 3 were very successful, resulting in a 95% COD removal after 15 min. Treatment with Starbon adsorption was also effective, reaching up to 81% COD removal at pH 3 within 1 h. The combined treatment with Fenton's reagent and Starbon resulted in a 93% COD removal at a significantly reduced concentration of Fenton's reagent compared to the treatment with solo Fenton's reagent. This lower chemical dose has the advantage of reducing costs and lowering sludge generation.

Enhanced nitrogen removal from electroplating tail wastewater through two-staged anoxic-oxic (A/O) process.

PubMed

Yan, Xinmei; Zhu, Chunyan; Huang, Bin; Yan, Qun; Zhang, Guangsheng

2018-01-01

Consisted of anaerobic (ANA), anoxic-1 (AN1), aerobic-1 (AE1), anoxic-2 (AN2), aerobic-2 (AE2) reactors and sediment tank, the two-staged A/O process was applied for depth treatment of electroplating tail wastewater with high electrical conductivity and large amounts of ammonia nitrogen. It was found that the NH 4 + -N and COD removal efficiencies reached 97.11% and 83.00%, respectively. Besides, the short-term salinity shock of the control, AE1 and AE2 indicated that AE1 and AE2 have better resistance to high salinity when the concentration of NaCl ranged from 1 to 10g/L. Meanwhile, it was found through high-throughput sequencing that bacteria genus Nitrosomonas, Nitrospira and Thauera, which are capable of nitrogen removal, were enriched in the two-staged A/O process. Moreover, both salt-tolerant bacteria and halophili bacteria were also found in the combined process. Therefore, microbial community within the two-staged A/O process could be acclimated to high electrical conductivity, and adapted for electroplating tail wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Restoring stream habitat connectivity: a proposed method for prioritizing the removal of resident fish passage barriers.

PubMed

O'Hanley, Jesse R; Wright, Jed; Diebel, Matthew; Fedora, Mark A; Soucy, Charles L

2013-08-15

Systematic methods for prioritizing the repair and removal of fish passage barriers, while growing of late, have hitherto focused almost exclusively on meeting the needs of migratory fish species (e.g., anadromous salmonids). An important but as of yet unaddressed issue is the development of new modeling approaches which are applicable to resident fish species habitat restoration programs. In this paper, we develop a budget constrained optimization model for deciding which barriers to repair or remove in order to maximize habitat availability for stream resident fish. Habitat availability at the local stream reach is determined based on the recently proposed C metric, which accounts for the amount, quality, distance and level of connectivity to different stream habitat types. We assess the computational performance of our model using geospatial barrier and stream data collected from the Pine-Popple Watershed, located in northeast Wisconsin (USA). The optimization model is found to be an efficient and practical decision support tool. Optimal solutions, which are useful in informing basin-wide restoration planning efforts, can be generated on average in only a few minutes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fabrication and characterization of akaganeite/graphene oxide nanocomposite for arsenic removal from water

NASA Astrophysics Data System (ADS)

Trang, Nguyen Thi Thuy; Thy, Lu Thi Mong; Cuong, Pham Mai; Tu, Tran Hoang; Hieu, Nguyen Huu

2018-04-01

In this study, akageneite/graphene oxide (β-FeOOH/GO) nanocomposite was fabricated by in situ forced hydrolysis of iron (III) chloride. The structure and morphology of β-FeOOH/GO were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett- Teller (BET) specific surface area. XRD, FTIR, and TEM results indicated that β-FeOOH nanoparticles were successfully decorated on the surface of GO nanosheets. The BET specific surface area of β-FeOOH/GO was observed of 97.94 m2/g. The nanocomposite was used as an adsorbent for removal of arsenic (As5+) from water. Adsorption experiments were carried out to investigate contact time, pH values, and As5+ initial concentrations. The adsorption equilibrium time was reached within 180 minutes. The adsorption was well-fitted by a pseudo-second-order kinetic and Langmuir isotherm model. The maximum adsorption capacity of β-FeOOH/GO for As5+ ions of 94.34 mg/g that was calculated from the Langmuir model at pH 3. Accordingly, the nanocomposite β-FeOOH/GO could be considered as a highly efficient adsorbent for removing arsenic from water.

Simultaneous nutrient removal, optimised CO2 mitigation and biofuel feedstock production by Chlorogonium sp. grown in secondary treated non-sterile saline sewage effluent.

PubMed

Lee, Kwan Yin; Ng, Tsz Wai; Li, Guiying; An, Taicheng; Kwan, Ka Ki; Chan, King Ming; Huang, Guocheng; Yip, Ho Yin; Wong, Po Keung

2015-10-30

The phycoremediation process has great potential for effectively addressing environmental pollution. To explore the capabilities of simultaneous algal nutrient removal, CO2 mitigation and biofuel feedstock production from spent water resources, a Chlorogonium sp. isolated from a tilapia pond in Hong Kong was grown in non-sterile saline sewage effluent for a bioremediation study. With high removal efficiencies of NH3-N (88.35±14.39%), NO3(-)-N (85.39±14.96%), TN (93.34±6.47%) and PO4(3-)-P (91.80±17.44%), Chlorogonium sp. achieved a CO2 consumption rate of 58.96 mg L(-1) d(-1), which was optimised by the response surface methodology. Under optimised conditions, the lipid content of the algal biomass reached 24.26±2.67%. Overall, the isolated Chlorogonium sp. showed promising potential in the simultaneous purification of saline sewage effluent in terms of tertiary treatment and CO2 sequestration while delivering feedstock for potential biofuel production in a waste-recycling manner. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption behavior of hydrotalcite-like modified bentonite for Pb2+, Cu2+and methyl orange removal from water

NASA Astrophysics Data System (ADS)

Chen, Yu; Peng, Jingdong; Xiao, Huan; Peng, Huanjun; Bu, Lingli; Pan, Ziyu; He, Yan; Chen, Fang; Wang, Xiang; Li, Shiyu

2017-10-01

Hydrotalcite-like compound (HTlc) which contained lanthanum cation was prepared successfully. The title compound was characterized by thermogravimetry analysis, element analysis, X-ray fluorescence, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, as well as specific surface area. The study sought to investigate the adsorption of heavy metals and dye (Pb2+, Cu2+ and methyl orange) in aqueous solution on Ben-HTlc. For optimization of adsorption behavior of the three elements, the pH value, contact time, adsorbate concentration were optimized. As for Pb2+, Cu2+ and methyl orange (MO), the single-component adsorption generally reached the maximum quantity in first 20 min and their respective adsorption capacities were 384.6 mg g-1, 156.3 mg g-1 and 333.3 mg g-1 (pH = 6.5 ± 0.1), the adsorption affinities were in the following sequence Pb2+ > MO > Cu2+. The repeated adsorption and regeneration studies showed the promising application of Ben-HTlc. The breakthrough experimental consequence had shown that the synthesized Ben-HTlc could efficiently remove heavy metals and dye from water, suggesting the potential utilization of Ben-HTlc in pollutants removal.

MIL-68 (In) nano-rods for the removal of Congo red dye from aqueous solution.

PubMed

Jin, Li-Na; Qian, Xin-Ye; Wang, Jian-Guo; Aslan, Hüsnü; Dong, Mingdong

2015-09-01

MIL-68 (In) nano-rods were prepared by a facile solvothermal synthesis using NaOAc as modulator agent at 100°C for 30 min. The BET test showed that the specific surface area and pore volume of MIL-68 (In) nanorods were 1252 m(2) g(-1) and 0.80 cm(3) g(-1), respectively. The as-prepared MIL-68 (In) nanorods showed excellent adsorption capacity and rapid adsorption rate for removal of Congo red (CR) dye from water. The maximum adsorption capacity of MIL-68 (In) nanorods toward CR reached 1204 mg g(-1), much higher than MIL-68 (In) microrods and most of the previously reported adsorbents. The adsorption process of CR by MIL-68 (In) nano-rods was investigated and found to be obeying the Langmuir adsorption model in addition to pseudo-second-order rate equation. Moreover, the MIL-68 (In) nanorods showed an acceptable reusability after regeneration with ethanol. All information gives an indication that the as-prepared MIL-68 (In) nanorods show their potential as the adsorbent for highly efficient removal of CR in wastewater. Copyright © 2015 Elsevier Inc. All rights reserved.

Review on the fate of organic micropollutants in wastewater treatment and water reuse with membranes.

PubMed

Siegrist, H; Joss, A

2012-01-01

A brief review of the fate of micropollutants in membrane-based wastewater treatment due to sorption, stripping, biological degradation/transformation and membrane separation is discussed, to give an overview of these technologies due to the growing importance for water reuse purposes. Compared with conventional activated sludge treatment (CAS) micropollutant removal in membrane bioreactor (MBR) is slightly improved due to complete suspended solids removal and increased sludge age. For discharge to sensitive receiving waters advanced treatment, such as post-ozonation or activated carbon adsorption, is recommended. In water reuse plants nanofiltration (NF) and reverse osmosis (RO) efficiently reject micropollutants due to size exclusions as well as electrostatic and hydrophobic effects reaching potable quality. To remove micropollutants fully, additionally post-ozone or the addition of powdered activated carbon (PAC) have to be applied, which in parallel also reduce NDMA precursors. The concentrate has to be treated if disposed to sensitive receiving waters due to its high micropollutant concentration and ecotoxicity potential. The present review summarizes principles and capabilities for the most important membrane-based applications for wastewater treatment, i.e. porous membranes in MBRs (micro- or ultrafiltration) and dense membrane applications (NF and RO) for water reuse.

Aerobic Biodegradation Characteristic of Different Water-Soluble Azo Dyes

PubMed Central

Sheng, Shixiong; Liu, Bo; Hou, Xiangyu; Wu, Bing; Yao, Fang; Ding, Xinchun; Huang, Lin

2017-01-01

This study investigated the biodegradation performance and characteristics of Sudan I and Acid Orange 7 (AO7) to improve the biological dye removal efficiency in wastewater and optimize the treatment process. The dyes with different water-solubility and similar molecular structure were biologically treated under aerobic condition in parallel continuous-flow mixed stirred reactors. The biophase analysis using microscopic examination suggested that the removal process of the two azo dyes is different. Removal of Sudan I was through biosorption, since it easily assembled and adsorbed on the surface of zoogloea due to its insolubility, while AO7 was biodegraded incompletely and bioconverted, the AO7 molecule was decomposed to benzene series and inorganic ions, since it could reach the interior area of zoogloea due to the low oxidation-reduction potential conditions and corresponding anaerobic microorganisms. The transformation of NH3-N, SO42− together with the presence of tryptophan-like components confirm that AO7 can be decomposed to non-toxic products in an aerobic bioreactor. This study provides a theoretical basis for the use of biosorption or biodegradation mechanisms for the treatment of different azo dyes in wastewater. PMID:29278390

Chemically Modified Polyvinyl Chloride for Removal of Thionine Dye (Lauth’s Violet)

PubMed Central

Silva, Cleuzilene V.; Royer, Betina; Rodrigues Filho, Guimes; Cerqueira, Daniel A.; Assunção, Rosana M. N.

2017-01-01

The chemical modification of hydrophobic polymer matrices is an alternative way to elchange their surface properties. The introduction of sulfonic groups in the polymer changes the surface properties such as adhesion, wettability, catalytic ability, and adsorption capacity. This work describes the production and application of chemically modified polyvinyl chloride (PVC) as adsorbent for dyes removal. Chemical modification of PVC was evaluated by infrared spectroscopy and elemental analysis, which indicated the presence of sulfonic groups on PVC. The chemically modified PVC (PVCDS) showed an ion exchange capacity of 1.03 mmol−1, and efficiently removed the thionine dye (Lauth’s violet) from aqueous solutions, reaching equilibrium in 30 min. The adsorption kinetics was better adjusted for a pseudo second order model. This result indicates that the adsorption of thionine onto PVCDS occurs by chemisorption. Among the models for the state of equilibrium, SIPS and Langmuir exhibited the best fit to the experimental results and PVCDS showed high adsorption capacities (370 mg−1). Thus, it is assumed that the system presents homogeneous characteristics to the distribution of active sites. The modification promoted the formation of surface characteristics favorable to the dye adsorption by the polymer. PMID:29137158

Application of steel slag coated with sodium hydroxide to enhance precipitation-coagulation for phosphorus removal.

PubMed

Park, Taejun; Ampunan, Vanvimol; Maeng, Sungkyu; Chung, Eunhyea

2017-01-01

Phosphorus removal has been studied for decades to reduce the environmental impact of phosphorus in natural waterbodies. Slag has been applied for the phosphorus removal by several mechanisms. In this study, sodium hydroxide coating was applied on the slag surface to enhance the efficiency of precipitation-coagulation process. In the batch test, it was found that the capacity of the slag to maintain high pH decreases with increasing its exposure time to the aqueous solution. In the column test, the coarse-grained coated slag showed higher phosphorus removal efficiency than the fine-grained uncoated slag. The coated slag maintained pH higher than uncoated slag and, accordingly, the removal efficiency of phosphorus was higher. Especially, when pH was less than 8, the removal efficiency decreased significantly. However, coated slag provided an excess amount of aluminum and sodium. Thus, a return process to reuse aluminum and sodium as a coagulant was introduced. The return process yields longer lifespan of slag with higher phosphorus removal and lower concentration of cations in the effluent. With the return process, the phosphorus removal efficiency was kept higher than 60% until 150 bed volumes; meanwhile, the efficiency without return process became lower than 60% at 25 bed volumes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Decolourization of remazol black-5 textile dyes using moving bed bio-film reactor

NASA Astrophysics Data System (ADS)

Pratiwi, R.; Notodarmojo, S.; Helmy, Q.

2018-01-01

The desizing and dyeing processes in the textile industries produces wastewaster containing high concentration of organic matter and colour, so it needs treatment before released to environment. In this research, removal of azo dye (Remazol Black 5/RB 5) and organic as COD was performed using Moving Bed Biofilm Reactor (MBBR). MBBR is biological treatment process with attached growth media system that can increase removal of organic matter in textile wastewater. The effectiveness of ozonation as pre-treatment process to increase the removal efficiency in MBBR was studied. The results showed that in MBBR batch system with detention time of 1 hour, pre-treatment with ozonation prior to MBBR process able to increase the colour removal efficiency of up to 86.74%. While on the reactor without ozone pre-treatment, the colour removal efficiency of up to 68.6% was achieved. From the continuous reactor experiments found that both colour and COD removal efficiency depends on time detention of RB-5 dyes in the system. The higher of detention time, the higher of colour and COD removal efficiency. It was found that optimum removal of colour and COD was achieved in 24 hour detention time with its efficiency of 96.9% and 89.13%, respectively.

[Leaching Remediation of Copper and Lead Contaminated Lou Soil by Saponin Under Different Conditions].

PubMed

Deng, Hong-xia; Yang, Ya-li; Li, Zhen; Xu, Yan; Li, Rong-hua; Meng, Zhao-fu; Yang, Ya-ti

2015-04-01

In order to investigate the leaching remediation effect of the eco-friendly biosurfactant saponin for Cu and Pb in contaminated Lou soil, batch tests method was used to study the leaching effect of saponin solution on single Cu, Pb contaminated Lou soil and mixed Cu and Pb contaminated Lou soil under different conditions such as reaction time, mass concentration of saponin, pH, concentration of background electrolyte and leaching times. The results showed that the maximum leaching removal effect of Cu and Pb in contaminated Lou soil was achieved by complexation of the heavy metals with saponin micelle, when the mass concentration of saponin solution was 50 g x L(-1), pH was 5.0, the reaction time was 240 min, and there was no background electrolyte. In single and mixed contaminated Lou soil, the leaching percentages of Cu were 29.02% and 25.09% after a single leaching with 50 g x L(-1) saponin under optimal condition, while the single leaching percentages of Pb were 31.56% and 28.03%, respectively. The result indicated the removal efficiency of Pb was more significant than that of Cu. After 4 times of leaching, the cumulative leaching percentages of Cu reached 58.92% and 53.11%, while the cumulative leaching percentages of Pb reached 77.69% and 65.32% for single and mixed contaminated Lou soil, respectively. The fractionation results of heavy metals in soil before and after a single leaching showed that the contents of adsorbed and exchangeable Cu and Pb increased in the contaminated soil, while the carbonate-bound, organic bound and sulfide residual Cu and Pb in the contaminated Lou soil could be effectively removed by saponin.

Monitoring the fate and behavior of TiO2 nanoparticles: Simulated in a WWTP with industrial dye-stuff effluent according to OECD 303A.

PubMed

Mahlalela, Lwazi C; Ngila, Jane C; Dlamini, Langelihle N

2017-07-03

The use of nanoparticles (NPs) in several consumer products has led to them finding their way into wastewater treatment plants (WWTPs). Some of these NPs have photocatalytic properties, thus providing a possible solution to textile industries to photodegrade dyes from their wastewater. Thus, the interaction of NPs with industrial dye effluents is inevitable. The Organization for Economic Co-operation and development (OECD) guideline for testing of chemical 303A was employed to study the fate and behaviour of TiO 2 NPs in industrial dye-stuff effluent. This was due to the unavailability of NPs' fate and behaviour test protocols. The effect of TiO 2 NPs on the treatment process was ascertained by measuring chemical oxygen demand (COD) and 5-day biological oxygen demand (BOD5). Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to study the fate and behavior of TiO 2 NPs. Acclimatization of bacteria to target pollutants was a crucial factor for the treatment efficiency of activated sludge in a simulated wastewater treatment plant (SWTP). The acclimatization of the activated sludge to the synthetic industrial dye-stuff effluent was successfully achieved. Effect of TiO 2 NPs on the treatment process efficiency was then investigated. Addition of TiO 2 NPs had no effect on the treatment process as chemical oxygen demand (COD) removal remained >80%. Measured total plate count (TPC) affirmed that the addition of TiO 2 NPs had no effect on the treatment process. The removal of total nitrogen (TN) was not efficient as the treatment system was required to have an oxic and anoxic stage for efficient TN removal. Results from X-ray powder diffraction (XRD) confirmed that the anatase phase of the added TiO 2 NPs remained unchanged even after exposure to the treatment plant. Removal of the NPs from the influent was facilitated by biosorption of the NPs on the activated sludge. Nanoparticles received by wastewater treatment plants will therefore reach the environment through sludge waste dumped in landfill. About 90% of TiO 2 was retained in the activated sludge, and 10-11% escaped with the treated effluents. Scanning electron microscope (SEM) mapping micrographs together with an energy dispersive X-ray spectroscopy (EDS) confirmed the presence of Ti in the sludge.

Ozonation and ultrafiltration for the treatment of olive mill wastewaters: effect of key operating conditions and integration schemes.

PubMed

Martins, Rui C; Ferreira, Ana M; Gando-Ferreira, Licínio M; Quinta-Ferreira, Rosa M

2015-10-01

With the objective of reaching suitable techniques for olive mill wastewater treatment, ozonation and ultrafiltration were studied individually and combined. A continuous reactor was run for the treatment of a phenolic mixture mimicking an actual olive mill wastewater (OMW) by ozonation. The effect of the main operating parameters was analysed (pH, liquid flow rate and ozone inlet concentration). The increase of pH and ozone dose improved ozonation efficiency. As expected, the highest residence time led to higher steady-state degradation (35 % of chemical oxygen demand (COD) abatement). Even if the rise on ozone inlet gas concentration was able to remove COD in a higher extent, it should be taken into consideration that with the lowest oxidant load (15 g O3/m(3)), the maximum steady-state biochemical oxygen demand (BOD5)/COD ratio was reached which would reduce the process costs. These operating conditions (pH 9, 1 mL/min of liquid flow rate and 15 g O3/m(3)) were applied to an actual OMW leading to 80 % of phenolic content abatement and 12 % of COD removal at the steady state. Regarding ultrafiltration, it was concluded that the best total phenolic content (TPh) and COD abatement results (55 and 15 %) are attained for pH 9 and using a transmembrane pressure drop of 1 bar. Among the integration schemes that were tested, ultrafiltration followed by ozonation was able to reach 93 and 20 % of TPh and COD depletion, respectively. Moreover, this sequence led to an effluent with a BOD5/COD ratio of about 0.55 which means that it likely can be posteriorly refined in a municipal wastewater treatment plant.

Characterization of sorption processes for the development of low-cost pesticide decontamination techniques.

PubMed

Rojas, Raquel; Vanderlinden, Eva; Morillo, José; Usero, José; El Bakouri, Hicham

2014-08-01

The adsorption/desorption behavior of four pesticides (atrazine, alachlor, endosulfan sulfate and trifluralin) in aqueous solutions onto four adsorbents (sunflower seed shells, rice husk, composted sewage sludge and soil) was investigated. Pesticide determination was carried out using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. Maximum removal efficiency (73.9%) was reached using 1 g of rice husk and 50 mL of pesticide solution (200 μg L(-1)). The pseudo adsorption equilibrium was reached with 0.6 g organic residue, which was used in subsequent experiments. The pseudo-first-order, pseudo-second-order kinetics and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated. The first model was more suitable for the sorption of atrazine and alachlor while the pseudo-second-order best described endosulfan sulfate and trifluralin adsorption, which showed the fastest sorption rates. 4h was considered as the equilibrium time for determining adsorption isotherms. Experimental data were modeled by Langmuir and Freundlich models. In most of the studied cases both models can describe the adsorption process, although the Freundlich model was applicable in all cases. The sorption capacity increased with the hydrophobic character of the pesticides and decreased with their water solubility. Rice husk was revealed as the best adsorbent for three of the four studied pesticides (atrazine, alachlor and endosulfan sulfate), while better results were obtained with composted sewage sludge and sunflower seed shell for the removal of trifluralin. Although desorption percentages were not high (with the exception of alachlor, which reached a desorption rate of 57%), the Kfd values were lower than the Kf values for adsorption and all H values were below 100, indicating that the adsorption was weak. Copyright © 2014 Elsevier B.V. All rights reserved.

The transformation from anammox granules to deammonification granules in micro-aerobic system by facilitating indigenous ammonia oxidizing bacteria.

PubMed

Wang, Xiaolong; Gao, Dawen

2018-02-01

Granular deammonification process is a good way to retain aerobic and anaerobic ammonia oxidizing bacteria (AOB and anammox bacteria) and exhaust flocculent nitrite oxidizing bacteria (NOB). In this study, to facilitate indigenous AOB growth on anammox granules, by stepwise reducing influent nitrite, anammox granules were effectively transformed into deammonification granules in a micro-aerobic EGSB in 100 days. Total nitrogen removal efficiency of 90% and nitrogen removal rate of 2.3 g N/L/d were reached at stable deammonification stage. High influent FA and limited oxygen supply contributed suppression for Nitrospira-like NOB. In transition stages, Proteobacteria and Chloroflexi were always dominated. Anammox abundance decreased, while AOB abundance grew fast. Anammox bacteria and AOB were dominated by Brocadia fulgida and Nitrosomonas europaea, respectively. Denitrification activity and bacteria existed although without influent organic. The final AOB abundance was about 4.55-13.8 times more than anammox bacteria abundance, with almost equal potential activities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of volatile fatty acids and ammonia recovery from unstable anaerobic digesters with a microbial electrolysis cell.

PubMed

Cerrillo, Míriam; Viñas, Marc; Bonmatí, August

2016-11-01

Continuous assays with a microbial electrolysis cell (MEC) fed with digested pig slurry were performed to evaluate its stability and robustness to malfunction periods of an anaerobic digestion (AD) reactor and its feasibility as a strategy to recover ammonia. When performing punctual pulses of volatile fatty acids (VFA) in the anode compartment of the MEC, simulating a malfunction of the AD process, an increase in the current density was produced (up to 14 times, reaching values of 3500mAm(-2)) as a result of the added chemical oxygen demand (COD), especially when acetate was used. Furthermore, ammonium diffusion from the anode to the cathode compartment was enhanced and the removal efficiency achieved up to 60% during daily basis VFA pulses. An AD-MEC combined system has proven to be a robust and stable configuration to obtain a high quality effluent, with a lower organic and ammonium content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of coagulation pretreatment of leachate by response surface methodology.

PubMed

Lessoued, Ridha; Souahi, Fatiha; Castrillon Pelaez, Leonor

2017-11-01

Coagulation-flocculation is a relatively simple technique that can be used successfully for the treatment of old leachate by poly-aluminum chloride (PAC). The main objectives of this study are to design the experiments, build models and optimize the operating parameters, dosage m and pH, using the central composite design and response surface method. Developed for chemical organic matter (COD) and turbidity responses, the quadratic polynomial model is suitable for prediction within the range of simulated variables as it showed that the optimum conditions were m of 5.55 g/L at pH 7.05, with a determination coefficient R² at 99.33%, 99.92% and adjusted R² at 98.85% and 99.86% for both COD and turbidity. We confirm that the initial pH and PAC dosage have significant effects on COD and turbidity removal. The experimental data and model predictions agreed well and the removal efficiency of COD, turbidity, Fe, Pb and Cu reached respectively 61%, 96.4%, 97.1%, 99% and 100%.

Hydrogen production from continuous flow, microbial reverse-electrodialysis electrolysis cells treating fermentation wastewater.

PubMed

Watson, Valerie J; Hatzell, Marta; Logan, Bruce E

2015-11-01

A microbial reverse-electrodialysis electrolysis cell (MREC) was used to produce hydrogen gas from fermentation wastewater without the need for additional electrical energy. Increasing the number of cell pairs in the reverse electrodialysis stack from 5 to 10 doubled the maximum current produced from 60 A/m(3) to 120 A/m(3) using acetate. However, more rapid COD removal required a decrease in the anolyte hydraulic retention time (HRT) from 24 to 12 h to stabilize anode potentials. Hydrogen production using a fermentation wastewater (10 cell pairs, HRT=8 h) reached 0.9±0.1 L H2/Lreactor/d (1.1±0.1 L H2/g-COD), with 58±5% COD removal and a coulombic efficiency of 74±5%. These results demonstrated that consistent rates of hydrogen gas production could be achieved using an MREC if effluent anolyte COD concentrations are sufficient to produce stable anode potentials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Copper Ferrocyanide Functionalized Core-Shell Magnetic Silica Composites for the Selective Removal of Cesium Ions from Radioactive Liquid Waste.

PubMed

Lee, Hyun Kyu; Yang, Da Som; Oh, Wonzin; Choi, Sang-June

2016-06-01

The copper ferrocyanide functionalized core-shell magnetic silica composite (mag@silica-CuFC) was prepared and was found to be easily separated from aqueous solutions by using magnetic field. The synthesized mag@silica-CuFC composite has a high sorption ability of Cs owing to its strong affinity for Cs as well as the high surface area of the supports. Cs sorption on the mag@silica-CuFC composite quickly reached the sorption equilibrium after 2 h of contact time. The effect of the presence of salts with a high concentration of up to 3.5 wt% on the efficiency of Cs sorption onto the composites was also studied. The maximum sorption ability was found to be maintained in the presence of up to 3.5 wt% of NaCl in the solution. Considering these results, the mag@silica-CuFC composite has great potential for use as an effective sorbent for the selective removal of radioactive Cs ions.

Controlled electrochemical doping of graphene-based 3D nanoarchitecture electrodes for supercapacitors and capacitive deionisation.

PubMed

Abdelkader, A M; Fray, D J

2017-10-05

Chemically-doped graphenes are promising electrode materials for energy storage and electrosorption applications. Here, an affordable electrochemical green process is introduced to dope graphene with nitrogen. The process is based on reversing the polarity of two identical graphene oxide (GO) electrodes in molten KCl-LiCl-Li 3 N. During the cathodic step, the oxygen functional groups on the GO surface are removed through direct electro-deoxidation reactions or a reaction with the deposited lithium. In the anodic step, nitrogen is adsorbed onto the surface of graphene and subsequently reacts to form nitrogen-doped graphene. The doping process is controllable, and graphene with up to 7.4 at% nitrogen can be produced. The electrochemically treated electrodes show a specific capacitance of 320 F g -1 in an aqueous KOH electrolyte and maintain 96% of this value after 10 000 cycles. The electrodes also display excellent electrosorption performance in capacitive deionisation devices with the salt removal efficiency reaching up to 18.6 mg g -1 .

Biodiesel waste as source of organic carbon for municipal WWTP denitrification.

PubMed

Bodík, I; Blstáková, A; Sedlácek, S; Hutnan, M

2009-04-01

This paper presents the results of experiments to test biodiesel waste (glycerine--g-phase) as an organic carbon source for the removal of nitrate in a WWTP denitrification process. Investigation of g-phase was first centered on g-phase utilization as an external source for denitrification under laboratory conditions and consequently, after positive results from the laboratory investigation, g-phase was applied in the denitrification process in the WWTP Vrútky (35,000 PE). This WWTP had insufficient nitrogen removal via denitrification. Denitrification was insufficient due to an influent with a low BOD5/N ratio (1.7:1) entering into the activated sludge tank. Laboratory experiments and calculations showed that, to reach Ntotal concentration under 10 mg l(-1) in effluent, a biodiesel waste dose of 500 kg(COD) d(-1) was necessary. Glycerol phase (g-phase) dosing into the denitrification tank increased denitrification efficiency by 2.0 - 5.0 mg(NO)(3)(-N)l(-1) per 100 l of g-phase dose into the denitrification tank.

Application of anaerobic granular sludge for competitive biosorption of methylene blue and Pb(II): Fluorescence and response surface methodology.

PubMed

Shi, Li; Wei, Dong; Ngo, Huu Hao; Guo, Wenshan; Du, Bin; Wei, Qin

2015-10-01

This study assessed the biosorption of anaerobic granular sludge (AGS) and its capacity as a biosorbent to remove Pb(II) and methylene blue (MB) from multi-components aqueous solution. It emerged that the biosorption data fitted well to the pseudo-second-order and Langmuir adsorption isotherm models in both single and binary systems. In competitive biosorption systems, Pb(II) and MB will suppress each other's biosorption capacity. Spectroscopic analysis, including Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy were integrated to explain this interaction. Hydroxyl and amine groups in AGS were the key functional groups for sorption. Three-dimensional excitation-emission matrix (3D-EEM) implied that two main protein-like substances were identified and quenched when Pb(II) or MB were present. Response surface methodology (RSM) confirmed that the removal efficiency of Pb(II) and MB reached its peak when the concentration ratios of Pb(II) and MB achieved a constant value of 1. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of COD/SO4(2-) ratio on anaerobic treatment of landfill leachate during the start-up period.

PubMed

Yilmaz, Tuba; Erdirencelebi, Dilek; Berktay, Ali

2012-01-01

This study investigates the performance of an anaerobic baffled reactor (ABR) during the start-up period of raw young landfill leachate treatment at two chemical oxygen demand (COD) to SO4(2-) ratios of 20 and 4. The reactor was operated at ambient temperature and low organic loading rates (0.52, 0.76 and 1.05 kg COD/m3 per day). During the study, sulfate-reducing bacteria (SRB) activity increased at the lower ratio of COD/SO4(2-) producing higher levels of sulfide and alkalinity. The dissolved sulfide concentration reached an inhibitory level above 250 mg/L, which caused a sharp reduction in the total COD removal efficiency from 77-80% to 32%. Total volatile fatty acid (TVFA) production proceeded at a constant level despite increased organic loading. As the effluent total and organic COD concentrations increased, the inhibitory effect of the inborn sulfide was correlated to the limitation experienced in the hydrolysis/acidogenesis stages, and thus VFA production and organic matter removal.

Brown Trout removal effects on short-term survival and movement of Myxobolus cerebralis-resistant rainbow trout

USGS Publications Warehouse

Fetherman, Eric R.; Winkelman, Dana L.; Bailey, Larissa L.; Schisler, George J.; Davies, K.

2015-01-01

Following establishment of Myxobolus cerebralis (the parasite responsible for salmonid whirling disease) in Colorado, populations of Rainbow Trout Oncorhynchus mykissexperienced significant declines, whereas Brown Trout Salmo trutta densities increased in many locations across the state, potentially influencing the success of M. cerebralis-resistant Rainbow Trout reintroductions. We examined the effects of Brown Trout removal on the short-term (3-month) survival and movement of two crosses of reintroduced, M. cerebralis-resistant Rainbow Trout in the Cache la Poudre River, Colorado. Radio frequency identification passive integrated transponder tags and antennas were used to track movements of wild Brown Trout and stocked Rainbow Trout in reaches where Brown Trout had or had not been removed. Multistate mark–recapture models were used to estimate tagged fish apparent survival and movement in these sections 3 months following Brown Trout removal. A cross between the German Rainbow Trout and Colorado River Rainbow Trout strains exhibited similar survival and movement probabilities in the reaches, suggesting that the presence of Brown Trout did not affect its survival or movement. However, a cross between the German Rainbow Trout and Harrison Lake Rainbow Trout exhibited less movement from the reach in which Brown Trout had been removed. Despite this, the overall short-term benefits of the removal were equivocal, suggesting that Brown Trout removal may not be beneficial for the reintroduction of Rainbow Trout. Additionally, the logistical constraints of conducting removals in large river systems are substantial and may not be a viable management option in many rivers.

Aluminum and iron doped graphene for adsorption of methylated arsenic pollutants

NASA Astrophysics Data System (ADS)

Cortés-Arriagada, Diego; Toro-Labbé, Alejandro

2016-11-01

The ability of Al and Fe-doped graphene for the adsorption of trivalent and pentavalent methylated arsenic compounds was studied by quantum chemistry computations. The adsorption of trivalent methylarsenicals is reached with adsorption energies of 1.5-1.7 eV at neutral conditions; while, adsorption of pentavalent methylarsenicals reaches adsorption energies of 3.3-4.2 eV and 1.2-2.4 eV from neutral to low pH conditions, respectively. Moreover, the weakening of the interacting σAssbnd O bond in the pollutant structure played an important role in the stability of the adsorbent-adsorbate systems, determining the adsorption strength. In addition, the pollutant adsorption appears to be efficient in aqueous environments, with even high stability at ambient temperature; in this regard, it was determined that the trivalent and petavalent forms are mainly adsorbed in their neutral and anionic forms at neutral pH, respectively. Therefore, Al and Fe-doped graphene are considered as potential future materials for the removal of methylated arsenic pollutants.

Treatment of domestic wastewater with an anaerobic ceramic membrane bioreactor (AnCMBR).

PubMed

Yue, Xiaodi; Koh, Yoong Keat Kelvin; Ng, How Yong

2015-01-01

In this study, a ceramic membrane with a pore size of 80 nm was incorporated into an anaerobic membrane bioreactor for excellent stability and integrity. Chemical oxygen demand (COD) removal efficiencies by biodegradation reached 78.6 ± 6.0% with mixed liquor suspended solids (MLSS) of 12.8 ± 1.2 g/L. Even though the total methane generated was 0.3 ± 0.03 L/g CODutilized, around 67.4% of it dissolved in permeate and was lost beyond collection. As a result, dissolved methane was 2.7 times of the theoretical saturating concentration calculated from Henry's law. When transmembrane pressure (TMP) of the ceramic membrane reached 30 kPa after 25.3 d, 95.2% of the total resistance was attributed to the cake layer, which made it the major contributor to membrane fouling. Compared to the mixed liquor, cake layer was rich in colloids and soluble products that could bind the solids to form a dense cake layer. The Methanosarcinaceae family preferred to attach to the ceramic membranes.

Using Wet-FGD systems for mercury removal.

PubMed

Díaz-Somoano, Mercedes; Unterberger, Sven; Hein, Klaus R G

2005-09-01

A plan to control mercury emissions to the atmosphere and to establish mercury emission limits has recently been elaborated by the European Commission, making it necessary to devise an efficient and cost effective mercury removal technology. Towards this end wet flue gas desulfurization units appear as a promising option for multi-pollutant control. However, more investigation on mercury removal and a greater mercury removal efficiency are required to achieve this objective. In the present work scrubber chemistry and the application of various solid additives to enhance mercury removal in wet scrubbers is evaluated. The results obtained show a significant correlation between mercury removal efficiency and the pH of the scrubber slurry and SO2 concentration. A weaker correlation was observed between oxygen or slurry concentration and removal efficiency. Finally several solid oxides were found to be effective additives for enhancing mercury capture in wet scrubbers.

Removal of particulate matter emitted from a subway tunnel using magnetic filters.

PubMed

Son, Youn-Suk; Dinh, Trieu-Vuong; Chung, Sang-Gwi; Lee, Jai-Hyo; Kim, Jo-Chun

2014-01-01

We removed particulate matter (PM) emitted from a subway tunnel using magnetic filters. A magnetic filter system was installed on the top of a ventilation opening. Magnetic field density was increased by increasing the number of permanent magnet layers to determine PM removal characteristics. Moreover, the fan's frequency was adjusted from 30 to 60 Hz to investigate the effect of wind velocity on PM removal efficiency. As a result, PM removal efficiency increased as the number of magnetic filters or fan frequency increased. We obtained maximum removal efficiency of PM10 (52%), PM2.5 (46%), and PM1 (38%) at a 60 Hz fan frequency using double magnetic filters. We also found that the stability of the PM removal efficiency by the double filter (RSD, 3.2-5.8%) was higher than that by a single filter (10.9-24.5%) at all fan operating conditions.

Effect of digestion temperature and pH on treatment efficiency and evolution of volatile fatty acids during thermophilic aerobic digestion of model high strength agricultural waste.

PubMed

Ugwuanyi, J Obeta; Harvey, L M; McNeil, B

2005-04-01

Thermophilic aerobic digestion (TAD) of a model agricultural waste, potato peel slurry, at soluble chemical oxygen demand (COD) load equivalent to approximately 8.0 gl(-1), was carried out under batch conditions at 0.5 vvm aeration rate. Digestions were carried out at temperatures of 45, 50, 55, 60 and 65 degrees C (or left unregulated) without pH control to study the effect of digestion temperatures on TAD. The effects of digestion pH on the process were studied at pH 6.0, 7.0, 8.0, 9.0 and 9.5 (and in unregulated control) all at 55 degrees C. Except for digestion at 65 degrees C, which was inoculated extraneously using culture of Bacillus strearothermophilus all reactions were carried out using the populations indigenous to the waste. During digestion at different temperatures, the removal of soluble COD increased with temperature to reach a peak at 60 degrees C before declining slightly, removal of soluble solid (SS) followed similar pattern and reached peak at 65 degrees C being the highest temperature studied, while the degradation of TSS and TS (TSS + TS) decreased with an increase in temperature. Digestion at pH 7.0 was more efficient than at other pH values. Acetate was the predominant volatile fatty acid (VFA) in all the reactions and accounted for up to 90% of the total. Digestion at 60 degrees C led to the greatest accumulation of acetate, and this coincided with the period of highest oxygen uptake, and rapid consumption of soluble carbohydrate. Iso-valerate was also produced at all pH values. Digestion at 55 degrees C and also at pH 7.0 led to rapid and efficient processes with least accumulation of VFA and should be of interest in full-scale processes whenever it is practicable to regulate the digestion pH and temperature. The result of digestion at unregulated pH indicates that gradual adaptation may be used to achieve efficient treatment at elevated pH values. This would be of interest in full-scale processes where it is not practicable to tightly regulate digestion pH, and where the waste is produced at a pH value much higher than neutral.

Geomorphic and habitat response to a large-dam removal in a Mediterranean river

NASA Astrophysics Data System (ADS)

Harrison, L.; East, A. E.; Smith, D. P.; Bond, R.; Logan, J. B.; Nicol, C.; Williams, T.; Boughton, D. A.; Chow, K.

2017-12-01

The presence of large dams has fundamentally altered physical and biological processes in riverine ecosystems, and dam removal is becoming more common as a river restoration strategy. We used a before-after-control-impact study design to investigate the geomorphic and habitat response to removal of 32-m-high San Clemente Dam on the Carmel River, CA. The project represents the first major dam removal in a Mediterranean river and is also unique among large dam removals in that most reservoir sediment was sequestered in place. We found that in the first year post-removal, a sediment pulse migrated 3.5 km downstream, filling pools and the interstitial pore spaces of gravels with sand. These sedimentary and topographic changes initially reduced the overall quality of steelhead (O. mykiss) spawning and rearing habitat in impacted reaches. Over the second winter after dam removal, a sequence of high flows flushed large volumes of sand from pools and mobilized the river bed throughout much of the active channel. The floods substantially altered fluvial evolution in the upper part of the reservoir, promoting new avulsion and the subsequent delivery of gravel and large wood to below dam reaches. These geomorphic processes increased the availability of spawning-sized gravel and enhanced channel complexity in reaches within several km of the former dam, which should improve habitat for multiple life stages of steelhead. Results indicate that when most reservoir sediment remains impounded, high flows become more important drivers of geomorphic and habitat change than dam removal alone. In such cases, the rates at which biophysical processes are reestablished will depend largely on post-dam removal flow sequencing and the upstream supply of sediment and large wood.

Cost-effectiveness analysis of TOC removal from slaughterhouse wastewater using combined anaerobic-aerobic and UV/H2O2 processes.

PubMed

Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar

2014-02-15

The objective of this study is to evaluate the operating costs of treating slaughterhouse wastewater (SWW) using combined biological and advanced oxidation processes (AOPs). This study compares the performance and the treatment capability of an anaerobic baffled reactor (ABR), an aerated completely mixed activated sludge reactor (AS), and a UV/H2O2 process, as well as their combination for the removal of the total organic carbon (TOC). Overall efficiencies are found to be up to 75.22, 89.47, 94.53, 96.10, 96.36, and 99.98% for the UV/H2O2, ABR, AS, combined AS-ABR, combined ABR-AS, and combined ABR-AS-UV/H2O2 processes, respectively. Due to the consumption of electrical energy and reagents, operating costs are calculated at optimal conditions of each process. A cost-effectiveness analysis (CEA) is performed at optimal conditions for the SWW treatment by optimizing the total electricity cost, H2O2 consumption, and hydraulic retention time (HRT). The combined ABR-AS-UV/H2O2 processes have an optimal TOC removal of 92.46% at an HRT of 41 h, a cost of $1.25/kg of TOC removed, and $11.60/m(3) of treated SWW. This process reaches a maximum TOC removal of 99% in 76.5 h with an estimated cost of $2.19/kg TOC removal and $21.65/m(3) treated SWW, equivalent to $6.79/m(3) day. Copyright © 2014 Elsevier Ltd. All rights reserved.

Organic matters removal from landfill leachate by immobilized Phanerochaete chrysosporium loaded with graphitic carbon nitride under visible light irradiation.

PubMed

Hu, Liang; Liu, Yutang; Zeng, Guangming; Chen, Guiqiu; Wan, Jia; Zeng, Yunxiong; Wang, Longlu; Wu, Haipeng; Xu, Piao; Zhang, Chen; Cheng, Min; Hu, Tianjue

2017-10-01

This study investigated the technical applicability of a combination of Phanerochaete chrysosporium (P. chrysosporium) with photocatalyst graphitic carbon nitride (g-C 3 N 4 ) for organic matters removal from landfill leachate under visible light irradiation. Photocatalyst g-C 3 N 4 was well immobilized on the hyphae surface of P. chrysosporium by calcium alginate. The typical absorption edge in visible light region for g-C 3 N 4 was at about 460 nm, and the optical absorption bandgap of g-C 3 N 4 was estimated to be 2.70 eV, demonstrating the great photoresponsive ability of g-C 3 N 4 . An optimized g-C 3 N 4 content of 0.10 g in immobilized P. chrysosporium and an optimized immobilized P. chrysosporium dosage of 1.0 g were suitable for organic matters removal. The removal efficiency of total organic carbon (TOC) reached 74.99% in 72 h with the initial TOC concentration of 100 mg L -1 . In addition, the gas chromatography coupled with mass spectrometry (GC-MS) measurements showed that immobilized P. chrysosporium presented an outstanding removal performance for almost all organic compounds in landfill leachate, especially for the volatile fatty acids and long-chain hydrocarbons. The overall results indicate that the combination P. chrysosporium with photocatalyst g-C 3 N 4 for organic matters removal from landfill leachate may provide a more comprehensive potential for the landfill leachate treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

The removal of the trivalent chromium from the leather tannery wastewater: the optimisation of the electro-coagulation process parameters.

PubMed

GilPavas, E; Dobrosz-Gómez, I; Gómez-García, M Á

2011-01-01

The capacity of the electro-coagulation (EC) process for the treatment of the wastewater containing Cr3+, resulting from a leather tannery industry placed in Medellin (Colombia), was evaluated. In order to assess the effect of some parameters, such as: the electrode type (Al and/or Fe), the distance between electrodes, the current density, the stirring velocity, and the initial Cr3+ concentration on its efficiency of removal (%RCr+3), a multifactorial experimental design was used. The %RCr3+ was defined as the response variable for the statistical analysis. In order to optimise the operational values for the chosen parameters, the response surface method (RSM) was applied. Additionally, the Biological Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), and the Total Organic Carbon (TOC) were monitored during the EC process. The electrodes made of aluminium appeared to be the most effective in the chromium removal from the wastewater under study. At pH equal to 4.52 and at 28°C, the optimal conditions of Cr3+ removal using the EC process were found, as follows: the initial Cr3+ concentration=3,596 mg/L, the electrode gap=0.5 cm, the stirring velocity=382.3 rpm, and the current density=57.87 mA/cm2. At those conditions, it was possible to reach 99.76% of Cr3+ removal, and 64% and 61% of mineralisation (TOC) and COD removal, respectively. A kinetic analysis was performed in order to verify the response capacity of the EC process at optimised parameter values.

The Effectiveness of Organic Pollutants Removal in Constructed Wetland with Horizontal Sub-Surface Flow / Efektywność Usuwania Zanieczyszczeń Organicznych W Oczyszczalni Hydrofitowej

NASA Astrophysics Data System (ADS)

Jakubaszek, Anita; Sadecka, Zofia

2015-03-01

This paper presents the results of the research work related to the removal efficiency from wastewater organic pollutants and suspended solids at HSSF (horizontal subsurface flow) constructed wetland. The average effectiveness defined as loss of value COD in wastewater has reached 77%, for BOD5 - 80% and TOC - 82%. The effect of seasonal temperature changes and the period of plant vegetation and rest on the effectiveness of wastewater treatment were also analyzed. The results of the presented research showed a decrease in the efficiency of removing organic pollutants from wastewater and suspended solids in the autumn and winter. During the vegetation the object in Małyszyn has been characterized by the effectiveness of wastewater treatment at the level of 78% for COD, 82% for BOD5, and in the non-vegetation period the effectiveness has decreased up to 75% for COD and 74% for BOD5. During the plants growth the total suspension was removed in 88%, whereas during the plants rest efficiency of removing lowered to 69%. W pracy przedstawiono wyniki badań dotyczące efektywności usuwania ze ścieków zanieczyszczeń organicznych w oczyszczalni hydrofitowej. Średnia skuteczność oczyszczania wyrażona jako obniżenie wartości ChZT w ściekach była na poziomie 77%, dla BZT5 80%, a dla OWO 82%. Analizowano również wpływ sezonowych zmian temperatury oraz okresu wegetacji i spoczynku roślin na skuteczność oczyszczania ścieków. Wyniki badań wykazały obniżenie efektywności usuwania zanieczyszczeń organicznych ze ścieków wyrażonych przez ChZT i BZT5 oraz zawiesiny ogólnej w okresie jesienno-zimowym. W okresie wegetacyjnym obiekt w Małyszynie charakteryzował się efektywnością oczyszczania ścieków na poziomie: 78% dla ChZT, 82% dla BZT5, a w sezonie pozawegetacyjnym skuteczność uległa obniżeniu do 75% w przypadku ChZT oraz 74% dla BZT5. Zawiesina ogólna w okresie wegetacji trzciny usuwana była w 88%, a w okresie powegetacyjnym w 69%.

Rapid preparation of biosorbents with high ion exchange capacity from rice straw and bagasse for removal of heavy metals.

PubMed

Rungrodnimitchai, Supitcha

2014-01-01

This work describes the preparation of the cellulose phosphate with high ion exchange capacity from rice straw and bagasse for removal of heavy metals. In this study, rice straw and bagasse were modified by the reaction with phosphoric acid in the presence of urea. The introduced phosphoric group is an ion exchangeable site for heavy metal ions. The reaction by microwave heating yielded modified rice straw and modified bagasse with greater ion exchange capacities (∼3.62 meq/g) and shorter reaction time (1.5-5.0 min) than the phosphorylation by oil bath heating. Adsorption experiments towards Pb²⁺, Cd²⁺, and Cr³⁺ ions of the modified rice straw and the modified bagasse were performed at room temperature (heavy metal concentration 40 ppm, adsorbent 2.0 g/L). The kinetics of adsorption agreed with the pseudo-second-order model. It was shown that the modified rice straw and the modified bagasse could adsorb heavy metal ions faster than the commercial ion exchange resin (Dowax). As a result of Pb²⁺ sorption test, the modified rice straw (RH-NaOH 450W) removed Pb²⁺ much faster in the initial step and reached 92% removal after 20 min, while Dowax (commercial ion exchange resin) took 90 min for the same removal efficiency.

Production of a novel bioflocculant and its flocculation performance in aluminum removal.

PubMed

Li, Lixin; Ma, Fang; Zuo, Huimin

2016-04-02

A novel bioflocculant CBF with high flocculating activity, produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaericus F6 from soil, was investigated with regard to its production and flocculation performance in Al(III) removal. The most preferred carbon source, nitrogen source and C/N ratio (w/w) for strains F2 and F6 to produce CBF were glucose, urea and 20, respectively. The optimal inoculum size for CBF production was 10 % (v/v). The optimal initial pH, culture temperature and shaking speed were 7-8, 30°C and 140 r/min for 24 h, respectively, under which the flocculating activity of the bioflocculant reached 98.52 %. According to literature review, flocculant dosage, coagulant aid dosage, pH, hydraulic condition of coagulation and sedimentation time are considered as influencing parameters for CBF flocculation performance in Al(III) removal by L16(4(5)) orthogonal design. The optimal conditions for Al(III) removal obtained through analysis and verification experiments were as follows: CBF, 28 mg/L; coagulant aid, 1.5 mL/L; initial pH, 8.0; and hydraulic conditions of coagulation: stir speed, 160 r/min; stir time, 40 s; and sedimentation time, 30 min. Under the optimal conditions, the removal efficiency of Al(III) was 92.95 %. Overall, these findings indicate that bioflocculant CBF offers an effective alternative method of decreasing Al(III) during drinking water treatment.

Effect of powdered activated carbon technology on short-cut nitrogen removal for coal gasification wastewater.

PubMed

Zhao, Qian; Han, Hongjun; Xu, Chunyan; Zhuang, Haifeng; Fang, Fang; Zhang, Linghan

2013-08-01

A combined process consisting of a powdered activated carbon technology (PACT) and short-cut biological nitrogen removal reactor (SBNR) was developed to enhance the removal efficiency of the total nitrogen (TN) from the effluent of an upflow anaerobic sludge bed (UASB) reactor, which was used to treat coal gasification wastewater (CGW). The SBNR performance was improved with the increasing of COD and TP removal efficiency via PACT. The average removal efficiencies of COD and TP in PACT were respectively 85.80% and 90.30%. Meanwhile, the NH3-N to NO2-N conversion rate was achieved 86.89% in SBNR and the total nitrogen (TN) removal efficiency was 75.54%. In contrast, the AOB in SBNR was significantly inhibited without PACT or with poor performance of PACT in advance, which rendered the removal of TN. Furthermore, PAC was demonstrated to remove some refractory compounds, which therefore improved the biodegradability of the coal gasification wastewater. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Toxic Elements in Soil and Groundwater: Short-Time Study on Electrokinetic Removal of Arsenic in the Presence of other Ions

PubMed Central

Leszczynska, Danuta; Ahmad, Hafiz

2006-01-01

The electrokinetic technique is an emerging technology presently tested in situ to remove dissolved heavy metals from contaminated groundwater. There is a growing interest for using this system to cleanse clayey soil contaminated by toxic metallic ions. Currently, there are very few available non-destructive treatment methods that could be successfully applied in situ on low permeable type of soil matrix. The main objective of presented study was to validate and possibly enhance the overall efficiency of decontamination by the electrokinetic technique of the low permeable soil polluted by the arsenic in combination with chromium and copper ions. The chosen mixture of ions was imitating leak of pesticide well known as chromate copper arsenate (CCA). The chosen technique is showing a big promise to be used in the future as a portable, easy to install and run on sites with spills or leaks hard to reach otherwise; such as in the dense populated and urbanized areas. Laboratory electrokinetic experiments were designed to understand and possibly manipulate main mechanisms involved during forced migration of ions. All tests were conducted on artificially contaminated kaolinite (low permeable clay soil). Electrokinetic migration was inducted by the low voltage dc current applied through soil column. Series of experiments were designed to assess the efficiency of arsenic-chromium-copper remediation by applying (1) only dc current; and (2) by altering the soil environment. Obtained results showed that arsenic could be successfully removed from the soil in one day (25 hours) span. It was significant time reduction, very important during emergency response. Mass recovered at the end of each test depended on initial condition of soil and type of flushing solution. The best results were obtained, when soil was flushed with either NaOH or NaOCl (total removal efficiency 74.4% and 78.1%, respectively). Direct analysis of remained arsenic in soil after these tests confirmed substantial drop of the initial mass of arsenic in soil profile from 51.54 mg to 10.62 mg (NaOH) and 5.68 mg (NaOCl) after 25 hours of treatment. PMID:16823093

Aerobic spore-forming bacteria for assessing quality of drinking water produced from surface water.

PubMed

Mazoua, Stephane; Chauveheid, Eric

2005-12-01

Cryptosporidium and Giardia represent a major microbiological issue for drinking water production from surface water. As their monitoring through a treatment process is rather tedious and as low-concentration goals should be reached for drinking water, aerobic spore-forming bacteria (ASFB) have been studied as an indicator microorganism for a drinking water treatment plant using surface water. The results reveal that monitoring naturally occurring ASFB better highlights daily achievable performances and identifies unusual process events for global disinfection, for both physical and chemical treatment steps in a multi-barrier drinking water treatment plant. Advantages of ASFB over usual process parameters are that these microorganisms are more sensitive to process fluctuations. The use of ASFB also showed that the efficiency of ozone disinfection is not as significantly influenced by the water temperature as reported, despite similar or higher CT values applied during warmer periods. Thus, the disinfection of resistant microorganisms with ozone can also be an efficient process at lower water temperature. ASFB have been shown to be a conservative indicator for Cryptosporidium and Giardia up to a 1st stage filtration and the ASFB Log removals can be used to estimate Log removals for Cryptosporidium and Giardia: compared to ASFB, the Log removals for Cryptosporidium or Giardia are at least equal or 50% higher, respectively. Thus, the monitoring of ASFB along a drinking water treatment process could be a useful tool for performing risk analysis for parasites such as Cryptosporidium and Giardia, and would further allow integration of daily variability into a risk analysis.

Hemodiafiltration improves free light chain removal and normalizes κ/λ ratio in hemodialysis patients.

PubMed

Bourguignon, Chloé; Chenine, Leïla; Bargnoux, Anne Sophie; Leray-Moragues, Hélène; Canaud, Bernard; Cristol, Jean-Paul; Morena, Marion

2016-04-01

Serum free light chain (FLC) levels are correlated with chronic kidney disease (CKD) stages and are highest in patients on hemodialysis (HD). Aim of this study was to assess the FLC removal efficiency of Elisio™-210H dialyzer using either high-flux HD or on line high efficiency hemodiafiltration (HDF) modalities in CKD-5D patients. In this prospective and comparative study, 20 CKD-5D patients free from multiple myeloma were randomized in two groups: HD versus on line HDF. All patients were dialyzed with Elisio™-210H dialyzer. Serum samples were collected before and after the midweek dialysis session, before randomization and at the end of the study to measure κ and λ FLC concentrations. Reduction ratios were corrected for net ultrafiltration. For both HD and HDF mode, κ and λ FLC concentrations were significantly lower after dialysis than before but median reductions in κ and λ FLC levels were significantly higher in HDF versus HD groups (κ 73.5 vs. 65.5 %, p = 0.04 and λ 51.0 vs. 36.6 %, p = 0.07). After dialysis, all κ/λ ratio values were between 0.26 and 1.65 which is the reference range described in subjects with normal kidney function, for both HD and HDF groups (median κ/λ ratios were 0.80 [0.47-1.22] and 0.67 [0.50-0.79] respectively). This study shows the superiority of on line HDF compared with HD to remove both κ and λ FLC. Moreover, all post-dialysis κ/λ ratios reached normal reference range.

Drinking water decontamination by biological denitrification using fresh bamboo as inoculum source.

PubMed

Bucco, Samuel; Padoin, Natan; Netto, Willibaldo Schmidell; Soares, Hugo Moreira

2014-10-01

Groundwater contamination is becoming a serious problem in many Brazilian regions. European countries started to deal with this issue in the 1980s, mainly caused by the extensive usage of nitrogenous fertilizers and the absence of domestic wastewater treatment. Due to its high solubility, nitrate readily passes through the soil and reaches the aquifer. Thereafter, this ion moves, following groundwater flow, and can be found several kilometers from the area where the pollution occurred. Concern about nitrate contamination is due to the link found between this contaminant and various human health diseases, such as methemoglobin and cancer. Studies carried out in France enabled the design and implementation of several biological denitrification plants throughout the country, in order to remove nitrate from its contaminated groundwater. Heterotrophic denitrification facilities shown to be adequate to treat high water flows with satisfactory nitrate removal efficiency, especially when static media supports are employed. The objective of this research was to evaluate the existence of denitrifying microorganisms in bamboo (Bambusa tuldóides) and verify the feasibility of their use to inoculate a pilot-scale fixed-bed bioreactor. The support material selected to fill the bioreactor bed was commercial polypropylene Pall rings, since such support has a high porosity associated with a wide superficial area. The bioreactor was able to produce and retain a large amount of cells. Using ethanol as carbon source, nitrate (N-NO3(-)) removal efficiency of the bioreactor stood around 80 % for a maximum nitrogen loading rate of approximately 6.5 mg N-NO3 (-) L(-1) h(-1).

Optimizing COD removal from greywater by photoelectro-persulfate process using Box-Behnken design: assessment of effluent quality and electrical energy consumption.

PubMed

Ahmadi, Mehdi; Ghanbari, Farshid

2016-10-01

Greywater (GW) is a potential source for water reuse in various applications. However, GW treatment is still a vital issue in water reuse in cases of environmental standards and risk to public health. This study investigates optimization and modeling of a hybrid process for COD removal from GW. Persulfate (PS) was simultaneously activated by electrogenerated ferrous ion (EC) and UV to generate sulfate radical. Photoelectro-persulfate (PEPS) was optimized by Box-Behnken design and the effects of four variables (pH, PS dosage, current density, and electrolysis time) were evaluated on COD removal. The results and several coefficients showed that the obtained model was acceptable for predicting the COD removal. Moreover, under optimum conditions (pH = 6.9, PS = 8.8 mM, current density = 2.0 mA/cm(2), and 49.3 min electrolysis time), BOD5, turbidity, TSS, phosphate, and UV254 were effectively removed and COD and BOD5 values reached to discharge standards. Different configurations of the processes were assessed for COD removal. The order of COD removal efficiency followed: PS < Fe(II) < UV/PS ≤ Fe(II)/PS < Fe(II)/PS/UV < electrocoagulation ≤ electrocoagulation/UV < electro-PS < PEPS. The monitoring PS concentration during 60 min reaction time in the aforesaid processes indicated that PEPS could remarkably activate PS. The solution pH was also monitored and related results revealed that the presence of PS during the 10 min first time decreased pH value while production of hydroxide ion at cathode increased pH significantly. Finally, the contribution of electrochemical process in the electrical energy consumption was far less than that of photolysis process in hybrid PEPS process.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-06-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-05-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

[Removal of SO2 from flue gas by water vapor DC corona discharge].

PubMed

Sun, Ming; Wu, Yan

2006-07-01

The influence of several factors on removal rate of SO2 from flue gas in unsaturated water vapor DC corona discharge was researched. Furthermore, the experiments of the removal rate of SO2 in pulsed discharge increased by water vapor DC corona discharge plasma were conducted. The experiment system is supplied with multi-nozzle-plate electrodes and the flow of simulated flue gas is under 70 m3/h. The results show that removal rate of SO2 can be improved by increasing the concentration of water vapor, intensity of electric field or decreasing flow of simulated flue gas. In unsaturated water vapor DC corona discharge, removal rate of SO2 can be improved by 10%, when NH3 is added as NH3 and SO2 is in a mole ratio of two to one, it can reach 60%. The removal rate of SO2 can be increased by 5% in pulsed corona discharge and reach above 90%.

Effects of influent C/N ratios and treatment technologies on integral biogas upgrading and pollutants removal from synthetic domestic sewage.

PubMed

Xu, Jie; Wang, Xue; Sun, Shiqing; Zhao, Yongjun; Hu, Changwei

2017-09-07

Three different treatment technologies, namely mono-algae culture, algal-bacterial culture, and algal-fungal culture, were applied to remove pollutants form synthetic domestic sewage and to remove CO 2 from biogas in a photobioreactor. The effects of different initial influent C/N ratios on microalgal growth rates and pollutants removal efficiencies by the three microalgal cultures were investigated. The best biogas upgrading and synthetic domestic sewage pollutants removal effect was achieved in the algal-fungal system at the influent C/N ratio of 5:1. At the influent C/N ratio of 5:1, the algal-fungal system achieved the highest mean chemical oxygen demand (COD) removal efficiency of 81.92% and total phosphorus (TP) removal efficiency of 81.52%, respectively, while the algal-bacterial system demonstrated the highest mean total nitrogen (TN) removal efficiency of 82.28%. The average CH 4 concentration in upgraded biogas and the removal efficiencies of COD, TN, and TP were 93.25 ± 3.84% (v/v), 80.23 ± 3.92%, 75.85 ± 6.61%, and 78.41 ± 3.98%, respectively. These results will provide a reference for wastewater purification ad biogas upgrading with microalgae based technology.

A testing-coverage software reliability model considering fault removal efficiency and error generation.

PubMed

Li, Qiuying; Pham, Hoang

2017-01-01

In this paper, we propose a software reliability model that considers not only error generation but also fault removal efficiency combined with testing coverage information based on a nonhomogeneous Poisson process (NHPP). During the past four decades, many software reliability growth models (SRGMs) based on NHPP have been proposed to estimate the software reliability measures, most of which have the same following agreements: 1) it is a common phenomenon that during the testing phase, the fault detection rate always changes; 2) as a result of imperfect debugging, fault removal has been related to a fault re-introduction rate. But there are few SRGMs in the literature that differentiate between fault detection and fault removal, i.e. they seldom consider the imperfect fault removal efficiency. But in practical software developing process, fault removal efficiency cannot always be perfect, i.e. the failures detected might not be removed completely and the original faults might still exist and new faults might be introduced meanwhile, which is referred to as imperfect debugging phenomenon. In this study, a model aiming to incorporate fault introduction rate, fault removal efficiency and testing coverage into software reliability evaluation is developed, using testing coverage to express the fault detection rate and using fault removal efficiency to consider the fault repair. We compare the performance of the proposed model with several existing NHPP SRGMs using three sets of real failure data based on five criteria. The results exhibit that the model can give a better fitting and predictive performance.

Behavior of pharmaceuticals in waste water treatment plant in Japan.

PubMed

Matsuo, H; Sakamoto, H; Arizono, K; Shinohara, R

2011-07-01

The fate of pharmaceuticals in a wastewater treatment plant (WWTP) in Kumamoto, Japan with activated sludge treatment is reported. Selected pharmaceuticals were detected in influent. Results from the present study confirmed that Acetaminophen, Amoxicillin, Ampicillin and Famotidine were removed at a high rate (>90% efficiency). In contrast, removal efficiency of Ketoprofen, Losartan, Oseltamivir, Carbamazepine, and Diclofenac was relatively low (<50%). The selected pharmaceuticals were also detected in raw sludge. In digestive process, Indomethacin, Atenolol, Famotidine, Trimethoprim and Cyclofosamide were removed at a high (>70% efficiency). On the other hand, removal of Carbamazepine, Ketoprofen and Diclofenac was not efficient (<50%).

Effect of some operational parameters on the arsenic removal by electrocoagulation using iron electrodes

PubMed Central

2014-01-01

Arsenic contamination of drinking water is a global problem that will likely become more apparent in future years as scientists and engineers measure the true extent of the problem. Arsenic poisoning is preventable though as there are several methods for easily removing even trace amounts of arsenic from drinking water. In the present study, electrocoagulation was evaluated as a treatment technology for arsenic removal from aqueous solutions. The effects of parameters such as initial pH, current density, initial concentration, supporting electrolyte type and stirring speed on removal efficiency were investigated. It has been observed that initial pH was highly effective on the arsenic removal efficiency. The highest removal efficiency was observed at initial pH = 4. The obtained experimental results showed that the efficiency of arsenic removal increased with increasing current density and decreased with increasing arsenic concentration in the solution. Supporting electrolyte had not significant effects on removal, adding supporting electrolyte decreased energy consumption. The effect of stirring speed on removal efficiency was investigated and the best removal efficiency was at the 150 rpm. Under the optimum conditions of initial pH 4, current density of 0.54 mA/cm2, stirring speed of 150 rpm, electrolysis time of 30 minutes, removal was obtained as 99.50%. Energy consumption in the above conditions was calculated as 0.33 kWh/m3. Electrocoagulation with iron electrodes was able to bring down 50 mg/L arsenic concentration to less than 10 μg/L at the end of electrolysis time of 45 minutes with low electrical energy consumption as 0.52 kWh/m3. PMID:24991426

Synthesis Mechanism and Thermal Optimization of an Economical Mesoporous Material Using Silica: Implications for the Effective Removal or Delivery of Ibuprofen

PubMed Central

Kittappa, Shanmuga; Cui, Mingcan; Ramalingam, Malarvili; Ibrahim, Shaliza; Khim, Jeehyeong; Yoon, Yeomin; Snyder, Shane A.; Jang, Min

2015-01-01

Mesoporous silica materials (MSMs) were synthesized economically using silica (SiO2) as a precursor via a modified alkaline fusion method. The MSM prepared at 500°C (MSM–500) had the highest surface area, pore size, and volume, and the results of isotherms and the kinetics of ibuprofen (IBP) removal indicated that MSM–500 had the highest sorption capacity and fastest removal speed vs. SBA–15 and zeolite. Compared with commercial granular activated carbon (GAC), MSM–500 had a ~100 times higher sorption rate at neutral pH. IBP uptake by MSM–500 was thermodynamically favorable at room temperature, which was interpreted as indicating relatively weak bonding because the entropy (∆adsS, –0.07 J mol–1 K–1) was much smaller. Five times recycling tests revealed that MSM–500 had 83–87% recovery efficiencies and slower uptake speeds due to slight deformation of the outer pore structure. In the IBP delivery test, MSM–500 drug loading was 41%, higher than the reported value of SBA–15 (31%). The in vitro release of IBP was faster, almost 100%, reaching equilibrium within a few hours, indicating its effective loading and unloading characteristics. A cost analysis study revealed that the MSM was ~10–70 times cheaper than any other mesoporous silica material for the removal or delivery of IBP. PMID:26161510

Porous three-dimensional reduced graphene oxide merged with WO3 for efficient removal of radioactive strontium

NASA Astrophysics Data System (ADS)

Mu, Wanjun; Yu, Qianghong; Hu, rui; Li, Xingliang; Wei, Hongyuan; Jian, Yuan

2017-11-01

A simple hydrothermal method was used to prepare 3D nanostructured composite adsorbents of reduced graphene oxide (RGO) and WO3 (RGO/WO3). The analysis results suggest that it possesses a mesoporous 3D structure, in which WO3 nanorods are uniformly loaded on the surface of the RGO. Combining the benefits of GO and WO3, the composites exhibit a higher adsorption capacity for removing Sr2+ from aqueous solutions over a wide pH range (4-11). Adsorption isotherms show that the data fit the Langmuir isotherms well (R > 0.99), and the maximum adsorption capacity of 149.56 mg g-1 was achieved, much higher than that for GO, WO3 and other similar adsorbents. Sr2+ adsorption on RGO/WO3 reached equilibrium within 200 min. The fast adsorption and high adsorption rate of RGO/WO3 are mostly attributable to the plentiful adsorption sites provided by the dispersed WO3 nanoparticles on the RGO surface. Furthermore, the existence of Na+ ions has no obvious effect on the removal of Sr2+ ions by RGO/WO3, and RGO/WO3 adsorbent can be repeated at least 5 times without significant loss of adsorption capacity by adsorption-desorption experiment. Thus, RGO/WO3 shows the potential ability for removal of 90Sr from radioactive wastewater.

Application potential of grapefruit peel as dye sorbent: kinetics, equilibrium and mechanism of crystal violet adsorption.

PubMed

Saeed, Asma; Sharif, Mehwish; Iqbal, Muhammad

2010-07-15

This study reports the sorption of crystal violet (CV) dye by grapefruit peel (GFP), which has application potential in the remediation of dye-contaminated wastewaters using a solid waste generated by the citrus fruit juice industry. Batch adsorption of CV was conducted to evaluate the effect of initial pH, contact time, temperature, initial dye concentration, GFP adsorbent dose, and removal of the adsorbate CV dye from aqueous solution to understand the mechanism of sorption involved. Sorption equilibrium reached rapidly with 96% CV removal in 60 min. Fit of the sorption experimental data was tested on the pseudo-first and pseudo-second-order kinetics mathematical equations, which was noted to follow the pseudo-second-order kinetics better, with coefficient of correlation > or = 0.992. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacity of 254.16 mg g(-1). The GFP was regenerated using 1 M NaOH, with up to 98.25% recovery of CV and could be reused as a dye sorbent in repeated cycles. GFP was also shown to be highly effective in removing CV from aqueous solution in continuous-flow fixed-bed column reactors. The study shows that GFP has the potential of application as an efficient sorbent for the removal of CV from aqueous solutions. 2010 Elsevier B.V. All rights reserved.

Polyethylenimine functionalized Fe3O4/steam-exploded rice straw composite as an efficient adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Zhang, Shengli; Wang, Zhikai; Chen, Haoyu; Kai, Chengcheng; Jiang, Man; Wang, Qun; Zhou, Zuowan

2018-05-01

Polyethyleneimine functionalized Fe3O4/steam-exploded rice straw composite (Fe3O4-PEI-SERS), which combines magnetic separation with adsorption of PEI functionalized biosorbent, was successfully prepared via a simple glutaraldehyde crosslinking method. Its adsorption potential for the removal of Cr(VI) was systematically studied in batch mode. Results showed that Cr(VI) adsorption on Fe3O4-PEI-SESERS was highly pH-dependent, and the optimum pH was 2.0. The time to reach equilibrium was related to initial Cr(VI) concentration and was 1 and 6 h for 200 and 300 mg/L of Cr(VI), respectively. The adsorption system followed pseudo-second-order kinetic model and Langmuir isotherm. Its maximum adsorption capacity was 280.11, 317.46 and 338.98 mg/g at 25, 35 and 45 °C, respectively. The competitive uptake from coexisting ions (K+, Na+, Cu2+, Cl- and NO3-) was insignificant except SO42-. After six adsorption/desorption cycles, the adsorbent retained good adsorption capacity. The Cr(VI) removal involved its partial reduction into Cr(III). Due to the properties of high adsorption capacity, strong magnetic responsiveness, good reusability and Cr(VI) detoxification, the Fe3O4-PEI-SESERS has a potential application in Cr(VI) removal from wastewater.

Performance of novel hydroxyapatite nanowires in treatment of fluoride contaminated water.

PubMed

He, Junyong; Zhang, Kaisheng; Wu, Shibiao; Cai, Xingguo; Chen, Kai; Li, Yulian; Sun, Bai; Jia, Yong; Meng, Fanli; Jin, Zhen; Kong, Lingtao; Liu, Jinhuai

2016-02-13

Novel ultralong hydroxyapatite (HAP) nanowires were successfully prepared for fluoride removal for the first time. The fluoride adsorption on the HAP nanowires was studied on a batch mode. The results revealed that the adsorption data could be well described by the Freundlich model, and the adsorption kinetic followed the pseudo-second-order model. The maximum of adsorption capacity was 40.65 mg/g at pH 7.0 when the fluoride concentration is 200mg/L. The thermodynamic parameters suggested that the adsorption of fluoride was a spontaneous endothermic process. The FT-IR, XPS and Zeta potential analysis revealed that both anion exchange and electrostatic interactions were involved in the adsorption of fluoride. Furthermore, the HAP nanowires were made into HAP membrane through a simple process of suction filtration. Membrane filtration experiments revealed that the fluoride removal capabilities depended on the membrane thickness, flow rate and initial concentration of fluoride. The as-prepared membrane could remove fluoride efficiently through continues filtration. The filtered water amount could reach 350, 192, and 64 L/m(2) when the fluoride concentrations were 4, 5 and 8 ppm, respectively, using the HAP membrane with only 150 μm thickness. The as-synthesized ultralong HAP nanowires were thus demonstrated to be very effective and biocompatible adsorbents for fluoride removal from contaminated water. Copyright © 2015 Elsevier B.V. All rights reserved.

[Factors affecting biological removal of iron and manganese in groundwater].

PubMed

Xue, Gang; He, Sheng-Bing; Wang, Xin-Ze

2006-01-01

Factors affecting biological process for removing iron and manganese in groundwater were analyzed. When DO and pH in groundwater after aeration were 7.0 - 7.5 mg/L and 6.8 - 7.0 respectively, not only can the activation of Mn2+ oxidizing bacteria be maintained, but also the demand of iron and manganese removal can be satisfied. A novel inoculating approach of grafting mature filter material into filter bed, which is easier to handle than selective culture media, was employed in this research. However, this approach was only suitable to the filter material of high-quality manganese sand with strong Mn2+ adsorption capacity. For the filter material of quartz sand with weak adsorption capacity, only culturing and domesticating Mn2+ oxidizing bacteria by selective culture media can be adopted as inoculation in filter bed. The optimal backwashing rate of biological filter bed filled with manganese sand and quartz sand should be kept at a relatively low level of 6 - 9 L/(m2 x s) and 7 -11 L/( m2 x s), respectively. Then the stability of microbial phase in filter bed was not disturbed, and iron and manganese removal efficiency recovered in less than 5h. Moreover, by using filter material with uniform particle size of 1.0 - 1.2 mm in filter bed, the filtration cycle reached as long as 35 - 38h.

Hexavalent chromium adsorption from aqueous solution using carbon nano-onions (CNOs).

PubMed

Sakulthaew, Chainarong; Chokejaroenrat, Chanat; Poapolathep, Amnart; Satapanajaru, Tunlawit; Poapolathep, Saranya

2017-10-01

The capacity of carbon nano-onions (CNOs) to remove hexavalent chromium (Cr(VI)) from aqueous solution was investigated. Batch experiments were performed to quantify the effects of the dosage rate, pH, counter ions, and temperature. The adsorption of Cr(VI) onto CNOs was best described by a pseudo-second order rate expression. The adsorption efficiency increased with increasing adsorbent dosage and contact time and reached equilibrium in 24 h. The equilibrium data showed better compliance with a Langmuir isotherm than a Freundlich isotherm. Effective removal of Cr(VI) was demonstrated at pH values ranging from 2 to 10. The adsorption capacity of Cr(VI) was found to be highest (82%) at pH 3.4 and greatly depended on the solution pH. We found that Cr(VI) adsorption decreased with increasing pH over the pH range of 3.4-10. The adsorption capacity increased dramatically when the temperature increased from 10 °C to 50 °C regardless of the amount of CNOs used. Cr(VI) removal decreased by ∼13% when Zn(II), Cu(II), and Pb(II) were present, while there were no significant changes observed when NO 3 - or SO 4 2- was present. The overall results support that CNOs can be used as an alternative adsorbent material to remove Cr(VI) in the water treatment industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tuberous Sclerosis Syndrome

MedlinePlus

... removed and fertilized in a laboratory. When the embryos reach a certain size, 1 cell is removed ... question. The parents can then choose to transfer embryos which do not have the mutation. PGD has ...

The Detoxification and Degradation of Benzothiazole from the Wastewater in Microbial Electrolysis Cells

PubMed Central

Liu, Xianshu; Ding, Jie; Ren, Nanqi; Tong, Qingyue; Zhang, Luyan

2016-01-01

In this study, the high-production-volume chemical benzothiazole (BTH) from synthetic water was fully degraded into less toxic intermediates of simple organic acids using an up-flow internal circulation microbial electrolysis reactor (UICMER) under the hydraulic retention time (HRT) of 24 h. The bioelectrochemical system was operated at 25 ± 2 °C and continuous-flow mode. The BTH loading rate varied during experiments from 20 g·m−3·day−1 to 110 g·m−3·day−1. BTH and soluble COD (Chemical Oxygen Demand) removal efficiency reached 80% to 90% under all BTH loading rates. Bioluminescence based Shewanella oneidensis strain MR-1 ecotoxicity testing demonstrated that toxicity was largely decreased compared to the BTH wastewater influent and effluent of two control experiments. The results indicated that MEC (Microbial Electrolysis Cell) was useful and reliable for improving BTH wastewater treatment efficiency, enabling the microbiological reactor to more easily respond to the requirements of higher loading rate, which is meaningful for economic and efficient operation in future scale-up. PMID:27999421

The Detoxification and Degradation of Benzothiazole from the Wastewater in Microbial Electrolysis Cells.

PubMed

Liu, Xianshu; Ding, Jie; Ren, Nanqi; Tong, Qingyue; Zhang, Luyan

2016-12-20

In this study, the high-production-volume chemical benzothiazole (BTH) from synthetic water was fully degraded into less toxic intermediates of simple organic acids using an up-flow internal circulation microbial electrolysis reactor (UICMER) under the hydraulic retention time (HRT) of 24 h. The bioelectrochemical system was operated at 25 ± 2 °C and continuous-flow mode. The BTH loading rate varied during experiments from 20 g·m -3 ·day -1 to 110 g·m -3 ·day -1 . BTH and soluble COD (Chemical Oxygen Demand) removal efficiency reached 80% to 90% under all BTH loading rates. Bioluminescence based Shewanella oneidensis strain MR-1 ecotoxicity testing demonstrated that toxicity was largely decreased compared to the BTH wastewater influent and effluent of two control experiments. The results indicated that MEC (Microbial Electrolysis Cell) was useful and reliable for improving BTH wastewater treatment efficiency, enabling the microbiological reactor to more easily respond to the requirements of higher loading rate, which is meaningful for economic and efficient operation in future scale-up.

40 CFR Appendix A to Subpart I of... - Alternative Procedures for Measuring Point-of-Use Abatement Device Destruction or Removal Efficiency

Code of Federal Regulations, 2014 CFR

2014-07-01

... native AOI concentration (ppm) of the effluent during stable conditions. (14) Post-test calibration. At... or removal efficiencies must be determined while etching a substrate (product, dummy, or test). For... curves for the subsequent destruction or removal efficiency tests. (8) Mass location calibration. A...

Plaque removal efficacy of two children's toothbrushes: a one-month study.

PubMed

Benson, B J; Henyon, G; Grossman, E

1993-01-01

Reach Wonder Grip toothbrush for children was evaluated for plaque removal efficacy and compared to the Colgate Plus Junior (extra soft). The subjects appeared at the test site with overnight (14-18 hours) plaque accumulation. After qualifying for the study, sixty-eight (68) subjects were randomly assigned one of the test brushes. They then participated in the test evaluation at the clinical site wherein plaque levels were measured before and after a one minute brushing. Plaque removal efficacy was evaluated by the Global Plaque Index (percent of tooth surface covered by stained deposit). The subjects then used the assigned toothbrush at home for one month and returned to the test site to repeat the baseline evaluations. After their final plaque evaluations, the subjects were given a new toothbrush from each brand to use at home for one week and the subject and the parent were asked to complete a preference questionnaire. Sixty-seven (67) subjects completed the one month study. After one month's use of twice per day brushing, neither of the test toothbrushes demonstrated any evidence of oral irritation that could be related to toothbrushing. The results indicated that Reach Wonder Grip for Children was significantly more effective (p < 0.05) than Colgate Plus Junior in removing overall (Global) plaque at the initial exam period. The preference questionnaire indicated that the Reach Wonder Grip toothbrush was preferred by both the children and their parents. It is concluded that the new Reach Wonder Grip toothbrush for children is safe and effective for plaque removal.

Removal of pharmaceuticals from wastewater by biological processes, hydrodynamic cavitation and UV treatment.

PubMed

Zupanc, Mojca; Kosjek, Tina; Petkovšek, Martin; Dular, Matevž; Kompare, Boris; Širok, Brane; Blažeka, Željko; Heath, Ester

2013-07-01

To augment the removal of pharmaceuticals different conventional and alternative wastewater treatment processes and their combinations were investigated. We tested the efficiency of (1) two distinct laboratory scale biological processes: suspended activated sludge and attached-growth biomass, (2) a combined hydrodynamic cavitation-hydrogen peroxide process and (3) UV treatment. Five pharmaceuticals were chosen including ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac, and an active metabolite of the lipid regulating agent clofibric acid. Biological treatment efficiency was evaluated using lab-scale suspended activated sludge and moving bed biofilm flow-through reactors, which were operated under identical conditions in respect to hydraulic retention time, working volume, concentration of added pharmaceuticals and synthetic wastewater composition. The suspended activated sludge process showed poor and inconsistent removal of clofibric acid, carbamazepine and diclofenac, while ibuprofen, naproxen and ketoprofen yielded over 74% removal. Moving bed biofilm reactors were filled with two different types of carriers i.e. Kaldnes K1 and Mutag BioChip™ and resulted in higher removal efficiencies for ibuprofen and diclofenac. Augmentation and consistency in the removal of diclofenac were observed in reactors using Mutag BioChip™ carriers (85%±10%) compared to reactors using Kaldnes carriers and suspended activated sludge (74%±22% and 48%±19%, respectively). To enhance the removal of pharmaceuticals hydrodynamic cavitation with hydrogen peroxide process was evaluated and optimal conditions for removal were established regarding the duration of cavitation, amount of added hydrogen peroxide and initial pressure, all of which influence the efficiency of the process. Optimal parameters resulted in removal efficiencies between 3-70%. Coupling the attached-growth biomass biological treatment, hydrodynamic cavitation/hydrogen peroxide process and UV treatment resulted in removal efficiencies of >90% for clofibric acid and >98% for carbamazepine and diclofenac, while the remaining compounds were reduced to levels below the LOD. For ibuprofen, naproxen, ketoprofen and diclofenac the highest contribution to overall removal was attributed to biological treatment, for clofibric acid UV treatment was the most efficient, while for carbamazepine hydrodynamic cavitation/hydrogen peroxide process and UV treatment were equally efficient. Copyright © 2012 Elsevier B.V. All rights reserved.

Biodetoxification of toxins generated from lignocellulose pretreatment using a newly isolated fungus, Amorphotheca resinae ZN1, and the consequent ethanol fermentation.

PubMed

Zhang, Jian; Zhu, Zhinan; Wang, Xiaofeng; Wang, Nan; Wang, Wei; Bao, Jie

2010-11-22

Degradation of the toxic compounds generated in the harsh pretreatment of lignocellulose is an inevitable step in reducing the toxin level for conducting practical enzymatic hydrolysis and ethanol fermentation processes. Various detoxification methods have been tried and many negative outcomes were found using these methods, such as the massive freshwater usage and wastewater generation, loss of the fine lignocellulose particles and fermentative sugars and incomplete removal of inhibitors. An alternate method, biodetoxification, which degrades the toxins as part of their normal metabolism, was considered a promising option for the removal of toxins without causing the above problems. A kerosene fungus strain, Amorphotheca resinae ZN1, was isolated from the microbial community growing on the pretreated corn stover material. The degradation of the toxins as well as the lignocelluloses-derived sugars was characterized in different ways, and the results show that A. resinae ZN1 utilized each of these toxins and sugars as the sole carbon sources efficiently and grew quickly on the toxins. It was found that the solid-state culture of A. resinae ZN1 on various pretreated lignocellulose feedstocks such as corn stover, wheat straw, rice straw, cotton stalk and rape straw degraded all kinds of toxins quickly and efficiently. The consequent simultaneous saccharification and ethanol fermentation was performed at the 30% (wt/wt) solid loading of the detoxified lignocellulosic feedstocks without a sterilization step, and the ethanol titer in the fermentation broth reached above 40 g/L using food crop residues as feedstocks. The advantages of the present biodetoxification by A. resinae ZN1 over the known detoxification methods include zero energy input, zero wastewater generation, complete toxin degradation, processing on solid pretreated material, no need for sterilization and a wide lignocellulose feedstock spectrum. These advantages make it possible for industrial applications with fast and efficient biodetoxification to remove toxins generated during intensive lignocellulose pretreatment.

Development of a portable, modular unit for the optimization of ultrasound-assisted oxidative desulfurization of diesel

NASA Astrophysics Data System (ADS)

Wan, Meng-Wei

Due to the stringent rules requiring ultra-low sulfur content in diesel fuels, it is necessary to develop alternative methods of desulfurization of fossil fuel derived oil, such as diesel. Current technology is not sufficient to solve this problem. Ultrasound applied to oxidative desulfurization which combined three complementary techniques: ultrasonication, phase transfer catalysis (PTC) and transition metal catalyzed oxidation, has accomplished high sulfur removal in a short contact time at ambient temperature and atmospheric pressure. This research has successfully demonstrated that the higher oxidation efficiency of BT to BTO and free of any by-products by using tetraoctylammonium fluoride as phase transfer agent. The oxidation rate of BT to BTO increased with increasing the carbon chain length of QAS cations. Under the same length of carbon chain, the oxidation rate of BT to BTO increased with decreasing the molecular size of QAS anions. Moreover, for diesel fuels containing various levels of sulfur content, UAOD process followed by solvent extraction has demonstrated that the sulfur reduction can reach above 95 % removal efficiency or final sulfur content below 15 ppm in mild condition. For large-scale commercial production, this research has successfully developed and operated a continuous desulfurization unit, which consists of a sonoractor, an RF amplifier, a function generator, a pretreatment tank, and a pipeline system. A single unit only needed 2' x 4' x 1' space for installation. The results indicated that the remarkable 92% removal efficiency for the sulfur in marine logistic diesel, even at a treatment rate as high as 25 lb/hour which is approximately 2 barrels per day. Therefore, this sonoreactor demonstrated the feasibility of large-scale operation even in a relatively small installation with low capital investment and maintenance cost. It also ensures the safety considerations by operating with diluted hydrogen peroxide under ambient temperature and pressure.

Strategies to Combat Antibiotic Resistance in the Wastewater Treatment Plants

PubMed Central

Barancheshme, Fateme; Munir, Mariya

2018-01-01

The main goal of this manuscript is to review different treatment strategies and mechanisms for combating the antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in the wastewater environment. The high amount of antibiotics is released into the wastewater that may promote selection of ARB and ARGs which find their way into natural environments. Emerging microbial pathogens and increasing antibiotic resistance among them is a global public health issue. The propagation and spread of ARB and ARGs in the environment may result in an increase of antibiotic resistant microbial pathogens which is a worldwide environmental and public health concern. A proper treatment of wastewater is essential before its discharge into rivers, lake, or sewage system to prevent the spread of ARB and ARGs into the environment. This review discusses various treatment options applied for combating the spread of ARB and ARGs in wastewater treatment plants (WWTPs). It was reported that low-energy anaerobic–aerobic treatment reactors, constructed wetlands, and disinfection processes have shown good removal efficiencies. Nanomaterials and biochar combined with other treatment methods and coagulation process are very recent strategies regarding ARB and ARGs removal and need more investigation and research. Based on current studies a wide-ranging removal efficiency of ARGs can be achieved depending on the type of genes present and treatment processes used, still, there are gaps that need to be further investigated. In order to find solutions to control dissemination of antibiotic resistance in the environment, it is important to (1) study innovative strategies in large scale and over a long time to reach an actual evaluation, (2) develop risk assessment studies to precisely understand occurrence and abundance of ARB/ARGs so that their potential risks to human health can be determined, and (3) consider operating and environmental factors that affect the efficiency of each treatment mechanism. PMID:29387043

Spray scrubbing of particulate-laden SO(2) using a critical flow atomizer.

PubMed

Bandyopadhyay, Amitava; Biswas, Manindra Nath

2008-08-01

The performance of a spray tower using an energy efficient two-phase critical flow atomizer on the scrubbing of particulate-laden SO(2) using water and dilute NaOH is reported in this article. Experimentation revealed that SO(2) removal was enhanced due to presence of particles (fly-ash) and almost 100% removal efficiency was achieved in water scrubbing. The removal efficiency is elucidated in reference to atomizing air pressure, droplet diameter and droplet velocity besides other pertinent variables of the system studied. The presence of fly-ash particles improved the removal efficiency to about 20% within the range of variables studied. Empirical and semi-empirical correlations were developed for predicting the removal efficiency in water and dilute NaOH respectively. Predicted data fitted excellently well with experimental values. The performance of the spray tower is compared with the performances of existing systems and very encouraging results are obtained.

[Efficiency of photodecomposition of trace NDMA in water by UV irradiation].

PubMed

Xu, Bing-Bing; Chen, Zhong-Lin; Qi, Fei; Ma, Jun

2008-07-01

Efficiency of photodecomposition of trace NDMA by UV irradiation was investigated with analyzing the initial concentration of NDMA, solution pH, irradiation area, irradiation intensity and water quality effect on NDMA photolysis. NDMA could be effectively photodegraded by UV irradiation. The removal efficiency of NDMA was 97.5% after 5 min of UV irradiation. Effect of initial NDMA concentration on photodecomposition of NDMA was not remarkable. With pH value ascending, the removal rate of NDMA photodecomposition decreased. The yields of photoquantum were more under lower solution pH than that under higher pH. NDMA had fastest reaction rate at solution pH = 2.2. Removal efficiency of NDMA increased with the available irradiation area ascending. Increscent ultraviolet irradiation intensity was good for NDMA degradation. Water quality affected the removal of NDMA slightly. The removal efficiency of NDMA in tap water and Songhua River raw water were 96.7% and 94.8%, respectively.

Treatment of emulsified oils by electrocoagulation: pulsed voltage applications.

PubMed

Genc, Ayten; Bakirci, Busra

2015-01-01

The effect of pulsed voltage application on energy consumption during electrocoagulation was investigated. Three voltage profiles having the same arithmetic average with respect to time were applied to the electrodes. The specific energy consumption for these profiles were evaluated and analyzed together with oil removal efficiencies. The effects of applied voltages, electrode materials, electrode configurations, and pH on oil removal efficiency were determined. Electrocoagulation experiments were performed by using synthetic and real wastewater samples. The pulsed voltages saved energy during the electrocoagulation process. In continuous operation, energy saving was as high as 48%. Aluminum electrodes used for the treatment of emulsified oils resulted in higher oil removal efficiencies in comparison with stainless steel and iron electrodes. When the electrodes gap was less than 1 cm, higher oil removal efficiencies were obtained. The highest oil removal efficiencies were 95% and 35% for the batch and continuous operating modes, respectively.

Si photonics technology for future optical interconnection

NASA Astrophysics Data System (ADS)

Zheng, Xuezhe; Krishnamoorthy, Ashok V.

2011-12-01

Scaling of computing systems require ultra-efficient interconnects with large bandwidth density. Silicon photonics offers a disruptive solution with advantages in reach, energy efficiency and bandwidth density. We review our progress in developing building blocks for ultra-efficient WDM silicon photonic links. Employing microsolder based hybrid integration with low parasitics and high density, we optimize photonic devices on SOI platforms and VLSI circuits on more advanced bulk CMOS technology nodes independently. Progressively, we successfully demonstrated single channel hybrid silicon photonic transceivers at 5 Gbps and 10 Gbps, and 80 Gbps arrayed WDM silicon photonic transceiver using reverse biased depletion ring modulators and Ge waveguide photo detectors. Record-high energy efficiency of less than 100fJ/bit and 385 fJ/bit were achieved for the hybrid integrated transmitter and receiver, respectively. Waveguide grating based optical proximity couplers were developed with low loss and large optical bandwidth to enable multi-layer intra/inter-chip optical interconnects. Thermal engineering of WDM devices by selective substrate removal, together with WDM link using synthetic wavelength comb, we significantly improved the device tuning efficiency and reduced the tuning range. Using these innovative techniques, two orders of magnitude tuning power reduction was achieved. And tuning cost of only a few 10s of fJ/bit is expected for high data rate WDM silicon photonic links.

Cetylpyridinium chloride/magnetic alginate beads: an efficient system to remove p-nitrophenol from wastewater

NASA Astrophysics Data System (ADS)

Obeid, Layaly; Bee, Agnes; Talbot, Delphine; Abramson, Sebastien; Welschbillig, Mathias

2014-05-01

The adsorption process is one of the most efficient methods to remove pollutants from wastewater provided that suitable adsorbents are used. In order to produce environmentally safe adsorbents, natural polymers have received increasing attention in recent years. Thus, alginate, a polysaccharide extracted from brown seaweeds, is extensively used as inexpensive, non-toxic and efficient biosorbent. Furthermore, it has been shown that the encapsulation of magnetic materials in alginate beads facilitates their recovery from wastewater after the adsorption step, by the use of an external magnetic field gradient, obtained with a magnet or an electromagnet [1, 2]. In the present work, we have studied the adsorption affinity of magnetic alginate beads (called magsorbents)for p-nitrophenol (PNP), used as a hydrophobic pollutant, in presence of cetylpyridinium chloride (CPC), a cationic surfactant. First, the effect of different parameters (pH solution, contact time, surfactant initial concentration…) on the adsorption of CPC on the alginate beads was investigated. Adsorption of the surfactant occurs due to electrostatic attractions between its cationic head groups and negative carboxylate functions of the alginate beads. At larger surfactant concentrations, adsorption is also due to the interaction between the hydrocarbon chains of CPC forming aggregated structures capable of solubilizing hydrophobic solutes. In a second step, we showed that PNP can reach up to 95% of adsorption in the beads in presence of CPC, although the pollutant is poorly adsorbed by alginate in absence of the surfactant. At highest CPC concentrations, desorption occurs as micellar solubilization is preferred over coadsorption. Our magsorbents appear to efficiently remove both cationic surfactant and hydrophobic pollutants and we hope that this fundamental research will be helpful for the future development of magnetically assisted processes in water treatment plants. 1. A.Bee, D.Talbot, S.Abramson, V.Dupuis, Journal of colloid and Interface science, 362, 486-492 (2011). 2. L. Obeid, A. Bee, D. Talbot, S. Ben Jaafar, V. Dupuis, S. Abramson, V. Cabuil, M. Weschbillig, Journal of Colloid and Interface Science, 410, 52-58 (2013).

Comparison of the removal of ethanethiol in twin-biotrickling filters inoculated with strain RG-1 and B350 mixed microorganisms.

PubMed

An, Taicheng; Wan, Shungang; Li, Guiying; Sun, Lei; Guo, Bin

2010-11-15

This study aims to compare the biological degradation performance of ethanethiol using strain RG-1 and B350 commercial mixed microorganisms, which were inoculated and immobilized on ceramic particles in twin-biotrickling filter columns. The parameters affecting the removal efficiency, such as empty bed residence time (EBRT) and inlet concentration, were investigated in detail. When EBRT ranged from 332 to 66 s at a fixed inlet concentration of 1.05 mg L(-1), the total removal efficiencies for RG-1 and B350 both decreased from 100% to 70.90% and 47.20%, respectively. The maximum elimination capacities for RG-1 and B350 were 38.36 (removal efficiency=89.20%) and 25.82 g m(-3) h(-1) (removal efficiency=57.10%), respectively, at an EBRT of 83 s. The variation of the inlet concentration at a fixed EBRT of 110 s did not change the removal efficiencies which remained at 100% for RG-1 and B350 at concentrations of less than 1.05 and 0.64 mg L(-1), respectively. The maximum elimination capacities were 39.93 (removal efficiency=60.30%) and 30.34 g m(-3) h(-1) (removal efficiency=46.20%) for RG-1 and B350, respectively, at an inlet concentration of 2.03 mg L(-1). Sulfate was the main metabolic product of sulfur in ethanethiol. Based the results, strain RG-1 would be a better choice than strain B350 for the biodegradation of ethanethiol. Copyright © 2010 Elsevier B.V. All rights reserved.

Application of a low-cost biosurfactant in heavy metal remediation processes.

PubMed

da Rocha Junior, Rivaldo B; Meira, Hugo M; Almeida, Darne G; Rufino, Raquel D; Luna, Juliana M; Santos, Valdemir A; Sarubbo, Leonie A

2018-05-04

The industrial interest in microbial surfactants has intensified in recent years due to the characteristics of these compounds, such as biodegradability, low toxicity, and effectiveness in removing heavy metals and hydrophobic organic compounds from soil and water. This paper describes the production of a biosurfactant by the yeast Candida tropicalis grown in distilled water with 2.5% molasses, 2.5% frying oil and 4% corn steep liquor. The production of the biosurfactant reached 27 g/l in a 50-l bioreactor with a surface tension of 30 mN/m. Surface tension and engine oil emulsification assays demonstrated the stability of biosurfactant under extreme conditions of temperature and pH as well as in the presence of NaCl. Chemical structures of the biosurfactant were identified using GC-MS and NMR. The isolated biosurfactant was characterised as an anionic molecule capable of reducing the surface tension of water from 70 to 30 mN/m at 0.5% of the critical micelle concentration, with no toxic effects on plant seeds or brine shrimp. In tests involving both the crude and isolated biosurfactant for the removal of heavy metals from contaminated sand under dynamic conditions, the removal rates for Zn and Cu ranged from 30 to 80%, while the best removal rate for Pb was 15%. Tests in packed columns also confirmed the ability of biosurfactant to remove Cu and Zn at rates ranging from 45 to 65%. However, lead was not removed under static conditions. The removal kinetics demonstrated that 30 min was sufficient for the removal of metals and a single washing with the biosurfactant achieved greater removal efficiency. The use of the biosurfactant led to a significant reduction in the electrical conductivity of solutions containing heavy metals. The present findings as well as a brief economic analysis suggest the great potential of this agent for industrial remediation processes of soil and water polluted with inorganic contaminants.

Simultaneous removal of aniline, nitrogen and phosphorus in aniline-containing wastewater treatment by using sequencing batch reactor.

PubMed

Jiang, Yu; Wang, Hongyu; Shang, Yu; Yang, Kai

2016-05-01

The high removal efficiencies of traditional biological aniline-degrading systems always lead to accumulation of ammonium. In this study, simultaneous removal of aniline, nitrogen and phosphorus in a single sequencing batch reactor was achieved by using anaerobic/aerobic/anoxic (A/O/A) operational process. The removal efficiencies of COD, NH4(+)-N, TN, TP were over 95.80%, 83.03%, 87.13%, 90.95%, respectively in most cases with 250mgL(-1) of initial aniline at 6h cycle when DO was 5.5±0.5mgL(-1). Aniline was able to be completely degraded when initial concentrations were less than 750mgL(-1). When DO increased, the removal rate of NH4(+)-N and TP slightly increased along with the moderate decrease of removal efficiencies of TN. The variation of HRT had obvious influence on removal performance of pollutants. The system showed high removal efficiencies of aniline, COD and nutrients during the variation of operating conditions, which might contribute to disposal of aniline-rich industrial wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of dissolved organic matter concentration and composition on the removal efficiency of perfluoroalkyl substances (PFASs) during drinking water treatment.

PubMed

Kothawala, Dolly N; Köhler, Stephan J; Östlund, Anna; Wiberg, Karin; Ahrens, Lutz

2017-09-15

Drinking water treatment plants (DWTPs) are constantly adapting to a host of emerging threats including the removal of micro-pollutants like perfluoroalkyl substances (PFASs), while concurrently considering how background levels of dissolved organic matter (DOM) influences their removal efficiency. Two adsorbents, namely anion exchange (AE) and granulated active carbon (GAC) have shown particular promise for PFAS removal, yet the influence of background levels of DOM remains poorly explored. Here we considered how the removal efficiency of 13 PFASs are influenced by two contrasting types of DOM at four concentrations, using both AE (Purolite A-600 ® ) and GAC (Filtrasorb 400 ® ). We placed emphasis on the pre-equilibrium conditions to gain better mechanistic insight into the dynamics between DOM, PFASs and adsorbents. We found AE to be very effective at removing both PFASs and DOM, while largely remaining resistant to even high levels of background DOM (8 mg carbon L -1 ) and surprisingly found that smaller PFASs were removed slightly more efficiently than longer chained counterparts, In contrast, PFAS removal efficiency with GAC was highly variable with PFAS chain length, often improving in the presence of DOM, but with variable response based on the type of DOM and PFAS chain length. Copyright © 2017 Elsevier Ltd. All rights reserved.

Initial Geomorphic Responses to Removal of Milltown Dam, Clark Fork River, Montana, USA

NASA Astrophysics Data System (ADS)

Wilcox, A. C.; Brinkerhoff, D.; Woelfle-Erskine, C.

2008-12-01

The removal of Milltown Dam on the Clark Fork River, Montana, USA, is creating a field-scale experiment on upstream and downstream responses to dam removal and on how gravel-bed rivers respond to sediment pulses. Milltown Dam was removed in 2008, reconnecting the Clark Fork River to its upstream basin in terms of sediment transport and fish passage. This dam removal is especially notable because (1) it is the largest dam removal to date in the United States in terms of the volume of reservoir sediment potentially available for downstream transport (over 3 million m3; 1.7 million m3 are being mechanically removed); and (2) the dam is the downstream end of the largest Superfund site in the United States, the Clark Fork Complex, and reservoir sediments are composed largely of contaminated mine tailings. Data collection on pre- and post-dam removal channel morphology, bed sediment characteristics, and sediment loads are being used to investigate spatial and temporal patterns of sediment transport and deposition associated with this dam removal. In the first several months following breaching of the dam, snowmelt runoff with a 3-year recurrence interval peak caused substantial erosion and downstream transport of metals-laden sediments from Milltown reservoir. Reservoir sediments in the Clark Fork arm of Milltown reservoir eroded at levels far exceeding modeling predictions as a result of both incision to the new base level created by dam removal and bank retreat of over 200 m in reaches upstream of a constructed bypass reach and remediation area. Copper and other metals in these eroded reservoir sediments provide a tracer for identifying whether sediment deposits observed downstream of the dam originated from Milltown reservoir or uncontaminated tributaries and indicate that Milltown sediments have reached over 200 km downstream. Downstream deposition has been greatest along channel margins and in side-channel areas, whereas the transport capacity of the active channel has limited channel changes there.

Mechanical energy expenditures and movement efficiency in full body reaching movements.

PubMed

Sha, Daohang; France, Christopher R; Thomas, James S

2010-02-01

The effect of target location, speed, and handedness on the average total mechanical energy and movement efficiency is studied in 15 healthy subjects (7 males and 8 females with age 22.9 +/- 1.79 years old) performing full body reaching movements. The average total mechanical energy is measured as the time average of integration of joint power, potential energy, and kinetic energy respectively. Movement efficiency is calculated as the ratio of total kinetic energy to the total joint power and potential energy. Results show that speed and target location have significant effects on total mechanical energy and movement efficiency, but reaching hand only effects kinetic energy. From our findings we conclude that (1) efficiency in whole body reaching is dependent on whether the height of the body center of mass is raised or lowered during the task; (2) efficiency is increased as movement speed is increased, in part because of greater changes in potential energy; and (3) the CNS does not appear to use movement efficiency as a primary planning variable in full body reaching. It may be dependent on a combination of other factors or constraints.

Dam removal: Listening in

NASA Astrophysics Data System (ADS)

Foley, M. M.; Bellmore, J. R.; O'Connor, J. E.; Duda, J. J.; East, A. E.; Grant, G. E.; Anderson, C. W.; Bountry, J. A.; Collins, M. J.; Connolly, P. J.; Craig, L. S.; Evans, J. E.; Greene, S. L.; Magilligan, F. J.; Magirl, C. S.; Major, J. J.; Pess, G. R.; Randle, T. J.; Shafroth, P. B.; Torgersen, C. E.; Tullos, D.; Wilcox, A. C.

2017-07-01

Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (< 5 years) and do not adequately represent the diversity of dam types, watershed conditions, and dam-removal methods in the U.S.

Dam removal: Listening in

USGS Publications Warehouse

Foley, Melissa M.; Bellmore, James; O'Connor, James E.; Duda, Jeff; East, Amy E.; Grant, Gordon G.; Anderson, Chauncey; Bountry, Jennifer A.; Collins, Mathias J.; Connolly, Patrick J.; Craig, Laura S.; Evans, James E.; Greene, Samantha; Magilligan, Francis J.; Magirl, Christopher S.; Major, Jon J.; Pess, George R.; Randle, Timothy J.; Shafroth, Patrick B.; Torgersen, Christian E.; Tullos, Desiree D.; Wilcox, Andrew C.

2017-01-01

Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (< 5 years) and do not adequately represent the diversity of dam types, watershed conditions, and dam-removal methods in the U.S.

Fate of estrogens in a pilot-scale step-feed anoxic/oxic wastewater treatment system controlling by nitrogen and phosphorus removal.

PubMed

Chen, Qingcai; Li, Zebing; Hua, Xiaoyu

2018-05-01

The control measures for estrogens in the aquatic environment are topics of growing concern. It is a meaningful issue to finding optimal process parameters for efficient removal of estrogens with the purpose of efficient total nitrogen (TN) or total phosphorus (TP) removal in sewage treatment plants. The present paper is concerned with the relationships between the estrogen removal and TN or TP removal in a pilot-scale three-stage anoxic/oxic (A/O) system treating real municipal wastewater. The total removal efficiency for estrone (E1) and 17β-estradiol (E2) and their sulfate and glucuronide conjugates were on average 87% in the pilot-scale system. The concentrations of the sulfate and glucuronide conjugates of estrogens (E1 and E2) in the system were much lower than the estrogens, which might be caused by the rapid degradation of conjugates in the pilot-scale system. The average removal efficiencies of E1 and E2 and their sulfate and glucuronide conjugates were significantly lower under high TP removal conditions than those under high TN removal conditions that suggested that the ammonia oxidation promotes estrogen degradation. When the system achieved efficient TN removal, the concentrations of both E1 and E2 were generally lower in the aerobic zones than those in the anoxic zones. Instead, when the system achieved efficient TP removal conditions, the estrogen concentrations were higher in the aerobic zones than in the anoxic zones. However, it was thought that the variation of the concentrations of the estrogen conjugates had weak influence on concentrations of the free estrogens. The increase of the free estrogens in the aerobic zones could be attributed to the release of the estrogens adsorbed on the sludge. The variation of estrogens in a three-stage A/O system can be properly estimated and measured by a binary linear regression model with the variables of TP and TON (NO 2 - -N and NO 3 - -N), which is probably the important information for the improvement and optimization of wastewater treatment processes to obtain higher removal efficiency for estrogens.

A testing-coverage software reliability model considering fault removal efficiency and error generation

PubMed Central

Li, Qiuying; Pham, Hoang

2017-01-01

In this paper, we propose a software reliability model that considers not only error generation but also fault removal efficiency combined with testing coverage information based on a nonhomogeneous Poisson process (NHPP). During the past four decades, many software reliability growth models (SRGMs) based on NHPP have been proposed to estimate the software reliability measures, most of which have the same following agreements: 1) it is a common phenomenon that during the testing phase, the fault detection rate always changes; 2) as a result of imperfect debugging, fault removal has been related to a fault re-introduction rate. But there are few SRGMs in the literature that differentiate between fault detection and fault removal, i.e. they seldom consider the imperfect fault removal efficiency. But in practical software developing process, fault removal efficiency cannot always be perfect, i.e. the failures detected might not be removed completely and the original faults might still exist and new faults might be introduced meanwhile, which is referred to as imperfect debugging phenomenon. In this study, a model aiming to incorporate fault introduction rate, fault removal efficiency and testing coverage into software reliability evaluation is developed, using testing coverage to express the fault detection rate and using fault removal efficiency to consider the fault repair. We compare the performance of the proposed model with several existing NHPP SRGMs using three sets of real failure data based on five criteria. The results exhibit that the model can give a better fitting and predictive performance. PMID:28750091

Phosphorous removal from aqueous solution can be enhanced through the calcination of lime sludge.

PubMed

Bal Krishna, K C; Niaz, Mohamed R; Sarker, Dipok C; Jansen, Troy

2017-09-15

Water treatment plants generate an enormous amount of the sludge which is normally treated as waste. In the recent past, many investigations have been focused on developing an economical adsorbent using water treatment sludge to remove phosphorous (P) from aqueous solutions. However, the great extents of the studies have been limited in the use of alum- and iron-based sludges. This study, therefore, investigated the P removal performance of the calcined lime sludge. Calcined lime sludge at 700 °C significantly enhanced the P removal efficiency whereas marginal improvement was noted when the sludge calcined at 400 °C was tested. With increase P removal efficiency, final pH values of the solution also significantly increased. P removal efficiency of the calcined sludge decreased with increasing the initial P concentrations. However, the removal efficiency could be improved by increasing the weight of the sludge. Further analysis demonstrated that P removal trend followed both pseudo-second order and diffusion-chemisorption kinetics signifying the P removal is potentially due to a multi-mechanistic reaction in which, the process is controlled by intra-particle diffusion followed by chemisorptions. Copyright © 2017 Elsevier Ltd. All rights reserved.