Evaluation of Simultaneous Nutrient and COD Removal with Polyhydroxybutyrate (PHB) Accumulation Using Mixed Microbial Consortia under Anoxic Condition and Their Bioinformatics Analysis

PubMed Central

Jena, Jyotsnarani; Kumar, Ravindra; Dixit, Anshuman; Pandey, Sony; Das, Trupti

2015-01-01

Simultaneous nitrate-N, phosphate and COD removal was evaluated from synthetic waste water using mixed microbial consortia in an anoxic environment under various initial carbon load (ICL) in a batch scale reactor system. Within 6 hours of incubation, enriched DNPAOs (Denitrifying Polyphosphate Accumulating Microorganisms) were able to remove maximum COD (87%) at 2g/L of ICL whereas maximum nitrate-N (97%) and phosphate (87%) removal along with PHB accumulation (49 mg/L) was achieved at 8 g/L of ICL. Exhaustion of nitrate-N, beyond 6 hours of incubation, had a detrimental effect on COD and phosphate removal rate. Fresh supply of nitrate-N to the reaction medium, beyond 6 hours, helped revive the removal rates of both COD and phosphate. Therefore, it was apparent that in spite of a high carbon load, maximum COD and nutrient removal can be maintained, with adequate nitrate-N availability. Denitrifying condition in the medium was evident from an increasing pH trend. PHB accumulation by the mixed culture was directly proportional to ICL; however the time taken for accumulation at higher ICL was more. Unlike conventional EBPR, PHB depletion did not support phosphate accumulation in this case. The unique aspect of all the batch studies were PHB accumulation was observed along with phosphate uptake and nitrate reduction under anoxic conditions. Bioinformatics analysis followed by pyrosequencing of the mixed culture DNA from the seed sludge revealed the dominance of denitrifying population, such as Corynebacterium, Rhodocyclus and Paraccocus (Alphaproteobacteria and Betaproteobacteria). Rarefaction curve indicated complete bacterial population and corresponding number of OTUs through sequence analysis. Chao1 and Shannon index (H’) was used to study the diversity of sampling. “UCI95” and “LCI95” indicated 95% confidence level of upper and lower values of Chao1 for each distance. Values of Chao1 index supported the results of rarefaction curve. PMID:25689047

Evaluation of simultaneous nutrient and COD removal with polyhydroxybutyrate (PHB) accumulation using mixed microbial consortia under anoxic condition and their bioinformatics analysis.

PubMed

Jena, Jyotsnarani; Kumar, Ravindra; Dixit, Anshuman; Pandey, Sony; Das, Trupti

2015-01-01

Simultaneous nitrate-N, phosphate and COD removal was evaluated from synthetic waste water using mixed microbial consortia in an anoxic environment under various initial carbon load (ICL) in a batch scale reactor system. Within 6 hours of incubation, enriched DNPAOs (Denitrifying Polyphosphate Accumulating Microorganisms) were able to remove maximum COD (87%) at 2 g/L of ICL whereas maximum nitrate-N (97%) and phosphate (87%) removal along with PHB accumulation (49 mg/L) was achieved at 8 g/L of ICL. Exhaustion of nitrate-N, beyond 6 hours of incubation, had a detrimental effect on COD and phosphate removal rate. Fresh supply of nitrate-N to the reaction medium, beyond 6 hours, helped revive the removal rates of both COD and phosphate. Therefore, it was apparent that in spite of a high carbon load, maximum COD and nutrient removal can be maintained, with adequate nitrate-N availability. Denitrifying condition in the medium was evident from an increasing pH trend. PHB accumulation by the mixed culture was directly proportional to ICL; however the time taken for accumulation at higher ICL was more. Unlike conventional EBPR, PHB depletion did not support phosphate accumulation in this case. The unique aspect of all the batch studies were PHB accumulation was observed along with phosphate uptake and nitrate reduction under anoxic conditions. Bioinformatics analysis followed by pyrosequencing of the mixed culture DNA from the seed sludge revealed the dominance of denitrifying population, such as Corynebacterium, Rhodocyclus and Paraccocus (Alphaproteobacteria and Betaproteobacteria). Rarefaction curve indicated complete bacterial population and corresponding number of OTUs through sequence analysis. Chao1 and Shannon index (H') was used to study the diversity of sampling. "UCI95" and "LCI95" indicated 95% confidence level of upper and lower values of Chao1 for each distance. Values of Chao1 index supported the results of rarefaction curve.

Ammonia nitrogen removal from aqueous solution by local agricultural wastes

NASA Astrophysics Data System (ADS)

Azreen, I.; Lija, Y.; Zahrim, A. Y.

2017-06-01

Excess ammonia nitrogen in the waterways causes serious distortion to environment such as eutrophication and toxicity to aquatic organisms. Ammonia nitrogen removal from synthetic solution was investigated by using 40 local agricultural wastes as potential low cost adsorbent. Some of the adsorbent were able to remove ammonia nitrogen with adsorption capacity ranging from 0.58 mg/g to 3.58 mg/g. The highest adsorption capacity was recorded by Langsat peels with 3.58 mg/g followed by Jackfruit seeds and Moringa peels with 3.37 mg/g and 2.64 mg/g respectively. This experimental results show that the agricultural wastes can be utilized as biosorbent for ammonia nitrogen removal. The effect of initial ammonia nitrogen concentration, pH and stirring rate on the adsorption process were studied in batch experiment. The adsorption capacity reached maximum value at pH 7 with initial concentration of 500 mg/L and the removal rate decreased as stirring rate was applied.

Experimental Results Of The Application Of Excimer Lasers In Surgical Treatment Of Cartilage Removal In Knee Joints

NASA Astrophysics Data System (ADS)

Moeller, Karl O.; Hohlbach, G.; Baretton, G.; Schramm, U.

1989-04-01

The aim of surgical therapy for osteoarthritic cartilage is the removal of the arthritic areas while maintaining the healthy tissue. Removal of calified areas by arthroscopy is preferably used in knee joints. The following investigations were performed to obtain the ablation rates during laser application in order to improve the ablation ratio of the calcified cartilage. For this purpose, specimens were immersed in tetracycline solution which has an absorption maximum at the laser's wavelength.

Investigation of the column performance of cadmium(II) biosorption by Cladophora crispata flocs in a packed bed

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

Aksu, Z.; Kutsal, T.; Caglar, A.

1998-03-01

In this study the biosorption of cadmium(II) ions to dried flocs of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The cadmium(II) removal performance of the column was investigated as a function of the cadmium(II)-bearing solution flow rate and the inlet cadmium(II) concentration. Removal and total removal percentages of cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet cadmium(II) concentration on the column capacity was also investigated. Data confirmed thatmore » early saturation and lower cadmium(II) removals were observed at higher flow rates and at higher cadmium(II) concentrations. Column experiments also showed that maximum specific cadmium(II) uptake values of C. crispata flocs were as high as those of other biomass sorbents.« less

Biodegradation of atrazine from wastewater using moving bed biofilm reactor under nitrate-reducing conditions: A kinetic study.

PubMed

Derakhshan, Zahra; Ehrampoush, Mohammad Hassan; Mahvi, Amir Hossein; Ghaneian, Mohammad Taghi; Mazloomi, Seyed Mohammad; Faramarzian, Mohammad; Dehghani, Mansooreh; Fallahzadeh, Hossein; Yousefinejad, Saeed; Berizi, Enayat; Bahrami, Shima

2018-04-15

In this study employed an anoxic moving bed biofilm reactor (AnMBBR) to evaluate the effects of hydraulic and toxic shocks on performance reactor. The results indicated a relatively good resistance of system against exercised shocks and its ability to return to steady-state conditions. In optimal conditions when there was the maximum rate of atrazine and soluble chemical oxygen demand (COD) removal were 74.82% and 99.29% respectively. Also, atrazine biodegradation rapidly declines in AnMBBR from 74% ± 0.05 in the presence of nitrate to 9.12% only 3 days after the nitrate was eliding from the influent. Coefficients kinetics was studied and the maximum atrazine removal rate was determined by modified Stover & Kincannon model (U max  = 9.87 g ATZ /m 3 d). Results showed that AnMBBR is feasible, easy, affordable, so suitable process for efficiently biodegrading toxic chlorinated organic compounds such as atrazine. Also, its removal mechanism in this system is co-metabolism. Copyright © 2018 Elsevier Ltd. All rights reserved.

UV photolysis for enhanced phenol biodegradation in the presence of 2,4,6-trichlorophenol (TCP).

PubMed

Song, Jiaxiu; Wang, Wenbing; Li, Rongjie; Zhu, Jun; Zhang, Yongming; Liu, Rui; Rittmann, Bruce E

2016-02-01

A bacterial strain isolated from activated sludge and identified as Bacillus amyloliquefaciens could biodegrade phenol, but 2,4,6-trichlorophenol (TCP) inhibited phenol biodegradation and biomass growth. UV photolysis converted TCP into dichlorocatechol, monochlorophenol, and dichlorophenol, and this relieved inhibition by TCP. Phenol-removal and biomass-growth rates were significantly accelerated after UV photolysis: the monod maximum specific growth rate (μ(max)) increased by 9% after TCP photolysis, and the half-maximum-rate concentration (K(S)) decreased by 36%. Thus, the major benefit of UV photolysis in this case was to transform TCP into a set of much-less-inhibitory products.

Liquid-phase membrane extraction of targeted pesticides from manufacturing wastewaters in a hollow fibre contactor with feed-stream recycle.

PubMed

Đorđević, Jelena; Vladisavljević, Goran T; Trtić-Petrović, Tatjana

2017-01-01

A two-phase membrane extraction in a hollow fibre contactor with feed-stream recycle was applied to remove selected pesticides (tebufenozide, linuron, imidacloprid, acetamiprid and dimethoate) from their mixed aqueous solutions. The contactor consisted of 50 polypropylene hollow fibres impregnated with 5% tri-n-octylphosphine oxide in di-n-hexyl ether. For low-polar pesticides with log P ≥ 2 (tebufenozide and linuron), the maximum removal efficiency increased linearly from 85% to 96% with increasing the feed flow rate. The maximum removal efficiencies of more polar pesticides were significantly higher under feed recirculation (86%) than in a continuous single-pass operation (30%). It was found from the Wilson's plot that the mass transfer resistance of the liquid membrane can be neglected for low-polar pesticides. The pesticide removals from commercial formulations were similar to those from pure pesticide solutions, indicating that built-in adjuvants did not affect the extraction 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.

Wettability Patterning for Enhanced Dropwise Condensation

NASA Astrophysics Data System (ADS)

Ghosh, Aritra; Ganguly, Ranjan; Megaridis, Constantine

2014-11-01

Dropwise condensation (DwC), in order to be sustainable, requires removal of the condensate droplets. This removal is frequently facilitated by gravity. The rate of DwC heat transfer depends strongly on the maximum departing droplet diameter. Based on wettability patterning, we present a facile technique designed to control the maximum droplet size in DwC within vapor/air atmospheres, and demonstrate how this approach can be used to enhance the corresponding heat transfer rate. We examine various hydrophilic-superhydrophilic patterns, which, respectively sustain DwC and filmwise (FwC) condensation on the substrate. The fabrication method does notemploy any hydrophobizing agent. By juxtaposing parallel lines of hydrophilic (CA ~ 78°) and superhydrophilic (CA ~ 0°) regions on the condensing surface, we create alternating domains of DwC and FwC. The average droplet size on the DwC domain is reduced by ~ 60% compared to the theoretical maximum, which corresponds to the line width. We compare heat transfer rate between unpatternend DwC surfaces and patterned DwC surfaces. Even after sacrificing 40% of condensing area, we achieve up to 20% improvement in condensate collection rate using an interdigitated superhydrophilic pattern, inspired by the vein network of plant leaves. The bioinspired interdigitated pattern is found to outperform the straight hydrophilic-superhydrophilic pattern, particularly under higher vapor loadings in an air/vapor ambient atmosphere. NSF STTR Grant 1331817 via NBD Nano.

Carbon stocks and accumulation rates in Pacific Northwest forests: role of stand age, plant community, and productivity

Treesearch

Andrew N. Gray; Thomas R. Whittier; Mark E. Harmon

2016-01-01

Forest ecosystems are removing significant amounts of carbon from the atmosphere. Both abiotic resource availability and biotic interactions during forest succession affect C accumulation rates and maximum C stocks. However, the timing and controls on the peak and decline in C accumulation rates as stands age, trees increase in size, and canopy gaps become prevalent...

Removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) from wastewaters by zero-valent iron (ZVI): predominant removal mechanism for effective SDBS removal.

PubMed

Takayanagi, Akari; Kobayashi, Maki; Kawase, Yoshinori

2017-03-01

Mechanisms for removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in wastewaters by zero-valent iron (ZVI) were systematically examined. The contributions of four removal mechanisms, i.e., reductive degradation, oxidative degradation, adsorption, and precipitation, changed significantly with solution pH were quantified and the effective removal of SDBS by ZVI was found to be attributed to the adsorption capability of iron oxides/hydroxides on ZVI surface at nearly neutral pH instead of the degradation at acidic condition. The fastest SDBS removal rate and the maximum TOC (total organic carbon) removal efficiency were obtained at pH 6.0. The maximum TOC removal at pH 6.0 was 77.8%, and the contributions of degradation, precipitation, and adsorption to TOC removal were 4.6, 14.9, and 58.3%, respectively. At pH 3.0, which is an optimal pH for oxidative degradation by the Fenton reaction, the TOC removal was only 9.8% and the contributions of degradation, precipitation, and adsorption to TOC removal were 2.3, 4.6, and 2.9%, respectively. The electrostatic attraction between dodecyl benzene sulfate anion and the iron oxide/hydroxide layer controlled the TOC removal of SDBS. The kinetic model based on the Langmuir-Hinshelwood/Eley-Rideal approach could successfully describe the experimental results for SDBS removal by ZVI with the averaged correlation coefficient of 0.994. ZVI was found to be an efficient material toward the removal of anionic surfactant at nearly neutral pH under the oxic condition.

Eco-friendly process combining physical-chemical and biological technics for the fermented dairy products waste pretreatment and reuse.

PubMed

Kasmi, Mariam; Hamdi, Moktar; Trabelsi, Ismail

2017-01-01

Residual fermented dairy products resulting from process defects or from expired shelf life products are considered as waste. Thus, dairies wastewater treatment plants (WWTP) suffer high input effluents polluting load. In this study, fermented residuals separation from the plant wastewater is proposed. In the aim to meet the municipal WWTP input limits, a pretreatment combining physical-chemical and biological processes was investigated to reduce residual fermented dairy products polluting effect. Yoghurt (Y) and fermented milk products (RL) were considered. Raw samples chemical oxygen demand (COD) values were assessed at 152 and 246 g.L -1 for Y and RL products, respectively. Following the thermal coagulation, maximum removal rates were recorded at 80 °C. Resulting whey stabilization contributed to the removal rates enhance to reach 72% and 87% for Y and RL samples; respectively. Residual whey sugar content was fermented using Candida strains. Bacterial growth and strains degrading potential were discussed. C. krusei strain achieved the most important removal rates of 78% and 85% with Y and RL medium, respectively. Global COD removal rates exceeded 93%.

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.

Implication of using different carbon sources for denitrification in wastewater treatments.

PubMed

Cherchi, Carla; Onnis-Hayden, Annalisa; El-Shawabkeh, Ibrahim; Gu, April Z

2009-08-01

Application of external carbon sources for denitrification becomes necessary for wastewater treatment plants that have to meet very stringent effluent nitrogen limits (e.g., 3 to 5 mgTN/L). In this study, we evaluated and compared three carbon sources--MicroC (Environmental Operating Solutions, Bourne, Massachusetts), methanol, and acetate-in terms of their denitrification rates and kinetics, effect on overall nitrogen removal performance, and microbial community structure of carbon-specific denitrifying enrichments. Denitrification rates and kinetics were determined with both acclimated and non-acclimated biomass, obtained from laboratory-scale sequencing batch reactor systems or full-scale plants. The results demonstrate the feasibility of the use of MicroC for denitrification processes, with maximum denitrification rates (k(dmax)) of 6.4 mgN/gVSSh and an observed yield of 0.36 mgVSS/mgCOD. Comparable maximum nitrate uptake rates were found with methanol, while acetate showed a maximum denitrification rate nearly twice as high as the others. The maximum growth rates measured at 20 degrees C for MicroC and methanol were 3.7 and 1.2 day(-1), respectively. The implications resulting from the differences in the denitrification rates and kinetics of different carbon sources on the full-scale nitrogen removal performance, under various configurations and operational conditions, were assessed using Biowin (EnviroSim Associates, Ltd., Flamborough, Ontario, Canada) simulations for both pre- and post-denitrification systems. Examination of microbial population structures using Automated Ribosomal Intergenic Spacer Analysis (ARISA) throughout the study period showed dynamic temporal changes and distinct microbial community structures of different carbon-specific denitrifying cultures. The ability of a specific carbon-acclimated denitrifying population to instantly use other carbon source also was investigated, and the chemical-structure-associated behavior patterns observed suggested that the complex biochemical pathways/enzymes involved in the denitrification process depended on the carbon sources used.

Influence of light presence and biomass concentration on nutrient kinetic removal from urban wastewater by Scenedesmus obliquus.

PubMed

Ruiz, J; Arbib, Z; Alvarez-Díaz, P D; Garrido-Pérez, C; Barragán, J; Perales, J A

2014-05-20

This work was aimed at studying the effect of light-darkness and high-low biomass concentrations in the feasibility of removing nitrogen and phosphorus from urban treated wastewater by the microalga Scenedesmus obliquus. Laboratory experiments were conducted in batch, where microalgae were cultured under different initial biomass concentrations (150 and 1500mgSSl(-1)) and light conditions (dark or illuminated). Nutrient uptake was more dependent on internal nutrient content of the biomass than on light presence or biomass concentration. When a maximum nitrogen or phosphorus content in the biomass was reached (around 8% and 2%, respectively), the removal of that nutrient was almost stopped. Biomass concentration affected more than light presence on the nutrient removal rate, increasing significantly with its increase. Light was only required to remove nutrients when the maximum nutrient storage capacity of the cells was reached and further growth was therefore needed. Residence times to maintain a stable biomass concentration, avoiding the washout of the reactor, were much higher than those needed to remove the nutrients from the wastewater. This ability to remove nutrients in the absence of light could lead to new configurations of reactors aimed to wastewater treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of dynamic operating conditions on nitrification in biological rapid sand filters for drinking water treatment.

PubMed

Lee, Carson O; Boe-Hansen, Rasmus; Musovic, Sanin; Smets, Barth; Albrechtsen, Hans-Jørgen; Binning, Philip

2014-11-01

Biological rapid sand filters are often used to remove ammonium from groundwater for drinking water supply. They often operate under dynamic substrate and hydraulic loading conditions, which can lead to increased levels of ammonium and nitrite in the effluent. To determine the maximum nitrification rates and safe operating windows of rapid sand filters, a pilot scale rapid sand filter was used to test short-term increased ammonium loads, set by varying either influent ammonium concentrations or hydraulic loading rates. Ammonium and iron (flock) removal were consistent between the pilot and the full-scale filter. Nitrification rates and ammonia-oxidizing bacteria and archaea were quantified throughout the depth of the filter. The ammonium removal capacity of the filter was determined to be 3.4 g NH4-N m(-3) h(-1), which was 5 times greater than the average ammonium loading rate under reference operating conditions. The ammonium removal rate of the filter was determined by the ammonium loading rate, but was independent of both the flow and influent ammonium concentration individually. Ammonia-oxidizing bacteria and archaea were almost equally abundant in the filter. Both ammonium removal and ammonia-oxidizing bacteria density were strongly stratified, with the highest removal and ammonia-oxidizing bacteria densities at the top of the filter. Cell specific ammonium oxidation rates were on average 0.6 × 10(2) ± 0.2 × 10(2) fg NH4-N h(-1) cell(-1). Our findings indicate that these rapid sand filters can safely remove both nitrite and ammonium over a larger range of loading rates than previously assumed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Removal of H2S pollutant from gasifier syngas by a multistage dual-flow sieve plate column wet scrubber.

PubMed

Kurella, Swamy; Bhukya, Pawan Kishan; Meikap, B C

2017-05-12

The objective of this study was to observe the performance of a lab-scale three-stage dual-flow sieve plate column scrubber for hydrogen sulfide (H 2 S) gas removal from a gas stream, in which the H 2 S concentration was similar to that of gasifier syngas. The tap water was used as scrubbing liquid. The gas and liquid were operated at flow rates in the range of 16.59 × 10 -4 -27.65 × 10 -4 Nm 3 /s and 20.649 × 10 -6 -48.183 × 10 -6 m 3 /s, respectively. The effects of gas and liquid flow rates on the percentage removal of H 2 S were studied at 50-300 ppm inlet concentrations of H 2 S. The increase in liquid flow rate, gas flow rate and inlet H 2 S concentration increased the percentage removal of H 2 S. The maximum of 78.88% removal of H 2 S was observed at 27.65 × 10 -4 Nm 3 /s gas flow rate and 48.183 × 10 -6 m 3 /s liquid flow rate for 300 ppm inlet concentration of H 2 S. A model has also been developed to predict the H 2 S gas removal by using the results from the experiments and adding the parameters that affect the scrubber's performance. The deviations between experimental and predicted H 2 S percentage removal values were observed as less than 16%.

Phosphorus optimization for simultaneous nitrate-contaminated groundwater treatment and algae biomass production using Ettlia sp.

PubMed

Rezvani, Fariba; Sarrafzadeh, Mohammad-Hossein; Seo, Seong-Hyun; Oh, Hee-Mock

2017-11-01

The effects of phosphorus concentration on the cell growth, nutrient assimilation, photosynthetic parameters, and biomass recovery of Ettlia sp. were evaluated with batch experiments using groundwater, 50mg/L of N-NO 3 - , and different concentrations of P-PO 4 3- : 0.5, 2.5, 5, and 10mg/L. The maximum biomass productivity and phosphorus removal rate were 0.2g/L/d and 5.95mg/L/d, respectively, with the highest phosphorus concentration of 10mg/L. However, a phosphorus concentration of 5mg/L (N:P=10) was sufficient to ensure an effective nitrogen removal rate of 11mg/L/d, maximum growth rate of 0.88/d, and biomass recovery of 0.72. The appropriate hydraulic retention time was considered as 4days on a large scale to meet the effluent limitation demands of water. While nitrogen depletion had a significant effect on the photosynthetic parameters and ratio of chlorophyll a to dry cell weight during the stationary phase, the effect of phosphorus was negligible during the cultivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrashort pulse high repetition rate laser system for biological tissue processing

DOEpatents

Neev, Joseph; Da Silva, Luiz B.; Matthews, Dennis L.; Glinsky, Michael E.; Stuart, Brent C.; Perry, Michael D.; Feit, Michael D.; Rubenchik, Alexander M.

1998-01-01

A method and apparatus is disclosed for fast, efficient, precise and damage-free biological tissue removal using an ultrashort pulse duration laser system operating at high pulse repetition rates. The duration of each laser pulse is on the order of about 1 fs to less than 50 ps such that energy deposition is localized in a small depth and occurs before significant hydrodynamic motion and thermal conduction, leading to collateral damage, can take place. The depth of material removed per pulse is on the order of about 1 micrometer, and the minimal thermal and mechanical effects associated with this ablation method allows for high repetition rate operation, in the region 10 to over 1000 Hertz, which, in turn, achieves high material removal rates. The input laser energy per ablated volume of tissue is small, and the energy density required to ablate material decreases with decreasing pulse width. The ablation threshold and ablation rate are only weakly dependent on tissue type and condition, allowing for maximum flexibility of use in various biological tissue removal applications. The use of a chirped-pulse amplified Titanium-doped sapphire laser is disclosed as the source in one embodiment.

Ultrashort pulse high repetition rate laser system for biological tissue processing

DOEpatents

Neev, J.; Da Silva, L.B.; Matthews, D.L.; Glinsky, M.E.; Stuart, B.C.; Perry, M.D.; Feit, M.D.; Rubenchik, A.M.

1998-02-24

A method and apparatus are disclosed for fast, efficient, precise and damage-free biological tissue removal using an ultrashort pulse duration laser system operating at high pulse repetition rates. The duration of each laser pulse is on the order of about 1 fs to less than 50 ps such that energy deposition is localized in a small depth and occurs before significant hydrodynamic motion and thermal conduction, leading to collateral damage, can take place. The depth of material removed per pulse is on the order of about 1 micrometer, and the minimal thermal and mechanical effects associated with this ablation method allows for high repetition rate operation, in the region 10 to over 1000 Hertz, which, in turn, achieves high material removal rates. The input laser energy per ablated volume of tissue is small, and the energy density required to ablate material decreases with decreasing pulse width. The ablation threshold and ablation rate are only weakly dependent on tissue type and condition, allowing for maximum flexibility of use in various biological tissue removal applications. The use of a chirped-pulse amplified Titanium-doped sapphire laser is disclosed as the source in one embodiment. 8 figs.

Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

PubMed

Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

2006-03-01

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

Modeling of copper sorption onto GFH and design of full-scale GFH adsorbers.

PubMed

Steiner, Michele; Pronk, Wouter; Boller, Markus A

2006-03-01

During rain events, copper wash-off occurring from copper roofs results in environmental hazards. In this study, columns filled with granulated ferric hydroxide (GFH) were used to treat copper-containing roof runoff. It was shown that copper could be removed to a high extent. A model was developed to describe this removal process. The model was based on the Two Region Model (TRM), extended with an additional diffusion zone. The extended model was able to describe the copper removal in long-term experiments (up to 125 days) with variable flow rates reflecting realistic runoff events. The four parameters of the model were estimated based on data gained with specific column experiments according to maximum sensitivity for each parameter. After model validation, the parameter set was used for the design of full-scale adsorbers. These full-scale adsorbers show high removal rates during extended periods of time.

Removal of enzymatic and fermentation inhibitory compounds from biomass slurries for enhanced biorefinery process efficiencies.

PubMed

Gurram, Raghu N; Datta, Saurav; Lin, Yupo J; Snyder, Seth W; Menkhaus, Todd J

2011-09-01

Within the biorefinery paradigm, many non-monomeric sugar compounds have been shown to be inhibitory to enzymes and microbial organisms that are used for hydrolysis and fermentation. Here, two novel separation technologies, polyelectrolyte polymer adsorption and resin-wafer electrodeionization (RW-EDI), have been evaluated to detoxify a dilute acid pretreated biomass slurry. Results showed that detoxification of a dilute acid pretreated ponderosa pine slurry by sequential polyelectrolyte and RW-EDI treatments was very promising, with significant removal of acetic acid, 5-hydroxymethyl furfural, and furfural (up to 77%, 60%, and 74% removed, respectively) along with >97% removal of sulfuric acid. Removal of these compounds increased the cellulose conversion to 94% and elevated the hydrolysis rate to 0.69 g glucose/L/h. When using Saccharomyces cerevisiae D(5)A for fermentation of detoxified slurry, the process achieved 99% of the maximum theoretical ethanol yield and an ethanol production rate nearly five-times faster than untreated slurry. Copyright © 2011 Elsevier Ltd. All rights reserved.

Valorization of lubricant-based wastewater for bacterial neutral lipids production: Growth-linked biosynthesis.

PubMed

Da Silva, Pedro D M P; Lima, Filipa; Alves, Maria Madalena; Bijmans, Martijn F M; Pereira, Maria Alcina

2016-09-15

Lipids produced by microorganisms are currently of great interest as raw material for either biofuels or oleochemicals production. Significant biosynthesis of neutral lipids, such as triacylglycerol (TAG) and wax esters (WE) are thought to be limited to a few strains. Hydrocarbonoclastic bacteria (HCB), key players in bioremediation of hydrocarbon contaminated ecosystems, are among this group of strains. Hydrocarbon rich wastewaters have been overlooked concerning their potential as raw material for microbial lipids production. In this study, lubricant-based wastewater was fed, as sole carbon source, to two HCB representative wild strains: Alcanivorax borkumensis SK2, and Rhodococcus opacus PD630. Neutral lipid production was observed with both strains cultivated under uncontrolled conditions of pH and dissolved oxygen. A. borkumensis SK2 was further investigated in a pH- and OD-controlled fermenter. Different phases were assessed separately in terms of lipids production and alkanes removal. The maximum TAG production rate occurred during stationary phase (4 mg-TAG/L h). The maximum production rate of WE-like compounds was 15 mg/L h, and was observed during exponential growth phase. Hydrocarbons removal was 97% of the gas chromatography (GC) resolved straight-chain alkanes. The maximum removal rate was observed during exponential growth phase (6 mg-alkanes/L h). This investigation proposes a novel approach for the management of lubricant waste oil, aiming at its conversion into valuable lipids. The feasibility of the concept is demonstrated under low salt (0.3%) and saline (3.3%) conditions, and presents clues for its technological development, since growth associated oil production opens the possibility for establishing continuous fermentation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Continuous treatment of high strength wastewaters using air-cathode microbial fuel cells.

PubMed

Kim, Kyoung-Yeol; Yang, Wulin; Evans, Patrick J; Logan, Bruce E

2016-12-01

Treatment of low strength wastewaters using microbial fuel cells (MFCs) has been effective at hydraulic retention times (HRTs) similar to aerobic processes, but treatment of high strength wastewaters can require longer HRTs. The use of two air-cathode MFCs hydraulically connected in series was examined to continuously treat high strength swine wastewater (7-8g/L of chemical oxygen demand) at an HRT of 16.7h. The maximum power density of 750±70mW/m 2 was produced after 12daysof operation. However, power decreased by 85% after 185d of operation due to serious cathode fouling. COD removal was improved by using a lower external resistance, and COD removal rates were substantially higher than those previously reported for a low strength wastewater. However, removal rates were inconsistent with first order kinetics as the calculated rate constant was an order of magnitude lower than rate constant for the low strength wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Effect of solids retention time on the bioavailability of organic carbon in anaerobically digested swine waste.

PubMed

Kinyua, Maureen N; Cunningham, Jeffrey; Ergas, Sarina J

2014-06-01

Anaerobic digestion (AD) can be used to stabilize and produce energy from livestock waste; however, digester effluents may require further treatment to remove nitrogen. This paper quantifies the effects of varying solids retention time (SRT) methane yield, volatile solids (VS) reduction and organic carbon bioavailability for denitrification during swine waste AD. Four bench-scale anaerobic digesters, with SRTs of 14, 21, 28 and 42 days, operated with swine waste feed. Effluent organic carbon bioavailability was measured using anoxic microcosms and respirometry. Excellent performance was observed for all four digesters, with >60% VS removal and CH4 yields between 0.1 and 0.3(m(3)CH4)/(kg VS added). Organic carbon in the centrate as an internal organic carbon source for denitrification supported maximum specific denitrification rates between 47 and 56(mg NO3(-)-N)/(g VSS h). The digester with the 21-day SRT had the highest CH4 yield and maximum specific denitrification rates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Positively charged microporous ceramic membrane for the removal of Titan Yellow through electrostatic adsorption.

PubMed

Cheng, Xiuting; Li, Na; Zhu, Mengfu; Zhang, Lili; Deng, Yu; Deng, Cheng

2016-06-01

To develop a depth filter based on the electrostatic adsorption principle, positively charged microporous ceramic membrane was prepared from a diatomaceous earth ceramic membrane. The internal surface of the highly porous ceramic membrane was coated with uniformly distributed electropositive nano-Y2O3 coating. The dye removal performance was evaluated through pressurized filtration tests using Titan Yellow aqueous solution. It showed that positively charged microporous ceramic membrane exhibited a flow rate of 421L/(m(2)·hr) under the trans-membrane pressure of 0.03bar. Moreover it could effectively remove Titan Yellow with feed concentration of 10mg/L between pH3 to 8. The removal rate increased with the enhancement of the surface charge properties with a maximum rejection of 99.6%. This study provides a new and feasible method of removing organic dyes in wastewater. It is convinced that there will be a broad market for the application of charged ceramic membrane in the field of dye removal or recovery from industry wastewater. Copyright © 2016. Published by Elsevier B.V.

Influence of SiO2 and graphene oxide nanoparticles on efficiency of biological removal process.

PubMed

Esmaeili-Faraj, Seyyed Hamid; Nasr Esfahany, Mohsen

2017-11-01

The effects of the presence of synthesized silica (SS) and exfoliated graphene oxide (EGO) on the removal of sulfide ion with activated sludge (AS) are experimentally investigated. The maximum removal efficiency of sulfide ion for AS without nanoparticles, and the samples with SS and EGO nanoparticles were 81%, 88% and 79%, respectively. Moreover, the maximum elimination capacity (EC max ) for the bioreactor with SS-nanoparticles is 7542 mg/L s, while the EC max of AS and EGO samples were 7075 and 6625 mg/L s, respectively. Two filamentous microbial strains as Gram-negative and Gram-positive bacteria are discerned that removed sulfide ion in the presence of nanoparticles. The measurement of mixture liquor volatile suspended solid that indicates the biomass growth rate during the test shows that the bioreactor containing SS-nanoparticles has more biomass content than the other samples. Our findings indicate that SS-nanoparticles with 0.1% wt. concentration in the bioreactor have no negative effects on the efficiency of the biological removal of sulfide and the presence of SS-nanoparticles even enhances the performance of the bioreactor. On the other side, a bioreactor with EGO nanosheets, as highly antibacterial nanoparticles, with 0.02% wt. concentration significantly influences the microbial growth and reduces sulfide removal efficiency.

Quantifying the capacity of compost buffers for treating agricultural runoff

NASA Astrophysics Data System (ADS)

Naranjo, S. A.; Beighley, R. E.; Buyuksonmez, F.

2007-12-01

Agricultural operations, specifically, avocado and commercial nurseries require frequent and significant fertilizing and irrigating which tends to result in excessive nutrient leaching and off-site runoff. The increased runoff contains high concentrations of nutrients which negatively impacts stream water quality. Researcher has demonstrated that best management practices such as compost buffers can be effective for reducing nutrient and sediment concentrations in agricultural runoff. The objective of this research is to evaluate both the hydraulic capacity and the nutrient removal efficiency of: (a) compost buffers and (b) buffers utilizing a combination of vegetation and compost. A series of experiments will be performed in the environmental hydraulics laboratory at San Diego State University. A tilting flume 12-m long, 27-cm wide and 25-cm deep will be used. Discharge is propelled by an axial flow pump powered by a variable speed motor with a maximum capacity of 30 liters per second. The experiments are designed to measure the ratio compost mass per flow rate per linear width. Two different discharges will be measured: (a) treatment discharge (maximum flow rate such that the buffer decreases the incoming nitrogen and phosphorus concentrations below a maximum allowable limit) and (b) breaking discharge (maximum flow rate the buffer can tolerate without structural failure). Experimental results are presented for the hydraulic analysis, and preliminary results are presented for the removal of nitrogen and phosphorus from runoff. The results from this project will be used to develop guidelines for installing compost buffers along the perimeters of nursery sites and avocado groves in southern California.

Effects of increasing inclusion rates of a low-fat distillers dried grains with solubles (LF-DDGS) in finishing broiler diets

USDA-ARS?s Scientific Manuscript database

The biodiesel industry is now removing corn oil from distillers dried grains with solubles (DDGS) in order to meet increasing demand. The objectives of this study were to determine the maximum inclusion rates in broiler diets fed from 28 to 42 d of age in the finishing phases of production and the ...

Converter slag-coal cinder columns for the removal of phosphorous and other pollutants.

PubMed

Yang, Jian; Wang, Su; Lu, Zhibo; Yang, Jian; Lou, Shanjie

2009-08-30

A mixture of converter slag and coal cinder as adsorbent for the removal of phosphorous and other pollutants was studied in the paper. The maximum P adsorption capacity, pH of solution, contact time and initial phosphate concentration were evaluated in batch experiments for the two materials firstly. The data of P sorption were best fitted to Langumir equation, and the maximum adsorption capacities of converter slag and coal cinder were 2.417 and 0.398 mg P/g, respectively. The pH of solutions with converter slag and coal cinder changed dramatically with time and closed to 8 in 8h, and the influence of initial pH on phosphate removal by coal cinder was more significant than by converter slag. Phosphate removal rate by converter slag decreased with increase of initial phosphate concentrations. Subsequently, two flow-through columns (Column 1#, V(converter slag):V(coal cinder)=1:5; Column 2#, V(converter slag):V(coal cinder)=1:3) were operated for the removal of phosphorous and other pollutants from the effluents of a vermifilter for nearly eleven months. Results indicated the average removal efficiency of total phosphorus, dissolved phosphorus, COD and NH(4)(+)-N by Column 1# were 44%, 56%, 31% and 67%, and by Column 2# were 42%, 54%, 24% and 57%, respectively. Column 1# had higher removal efficiency for P and other pollutants.

Silica removal in industrial effluents with high silica content and low hardness.

PubMed

Latour, Isabel; Miranda, Ruben; Blanco, Angeles

2014-01-01

High silica content of de-inked paper mill effluents is limiting their regeneration and reuse after membrane treatments such as reverse osmosis (RO). Silica removal during softening processes is a common treatment; however, the effluent from the paper mill studied has a low hardness content, which makes the addition of magnesium compounds necessary to increase silica removal. Two soluble magnesium compounds (MgCl₂∙6H₂O and MgSO₄∙7H₂O) were tested at five dosages (250-1,500 mg/L) and different initial pH values. High removal rates (80-90%) were obtained with both products at the highest pH tested (11.5). With these removal efficiencies, it is possible to work at high RO recoveries (75-85%) without silica scaling. Although pH regulation significantly increased the conductivity of the waters (at pH 11.5 from 2.1 to 3.7-4.0 mS/cm), this could be partially solved by using Ca(OH)₂ instead of NaOH as pH regulator (final conductivity around 3.0 mS/cm). Maximum chemical oxygen demand (COD) removal obtained with caustic soda was lower than with lime (15 vs. 30%). Additionally, the combined use of a polyaluminum coagulant during the softening process was studied; the coagulant, however, did not significantly improve silica removal, obtaining a maximum increase of only 10%.

Combined organic matter and nitrogen removal from a chemical industry wastewater in a two-stage MBBR system.

PubMed

Cao, S M S; Fontoura, G A T; Dezotti, M; Bassin, J P

2016-01-01

Pesticide-producing factories generate highly polluting wastewaters containing toxic and hazardous compounds which should be reduced to acceptable levels before discharge. In this study, a chemical industry wastewater was treated in a pre-denitrification moving-bed biofilm reactor system subjected to an increasing internal mixed liquor recycle ratio from 2 to 4. Although the influent wastewater characteristics substantially varied over time, the removal of chemical oxygen demand (COD) and dissolved organic carbon was quite stable and mostly higher than 90%. The highest fraction of the incoming organic matter was removed anoxically, favouring a low COD/N environment in the subsequent aerobic nitrifying tank and thus ensuring stable ammonium removal (90-95%). However, during pH and salt shock periods, nitrifiers were severely inhibited but gradually restored their full nitrifying capability as non-stressing conditions were reestablished. Besides promoting an increase in the maximum nitrification potential of the aerobic attached biomass from 0.34 to 0.63 mg [Formula: see text], the increase in the internal recycle ratio was accompanied by an increase in nitrogen removal (60-78%) and maximum specific denitrification rate (2.7-3.3 mg NOx(-)--N). Total polysaccharides (PS) and protein (PT) concentrations of attached biomass were observed to be directly influenced by the influent organic loading rate, while the PS/PT ratio mainly ranged from 0.3 to 0.5. Results of Microtox tests showed that no toxicity was found in the effluent of both the anoxic and aerobic reactors, indicating that the biological process was effective in removing residual substances which might adversely affect the receiving waters' ecosystem.

Eutrophic water purification efficiency using a combination of hydrodynamic cavitation and ozonation on a pilot scale.

PubMed

Li, Wei-Xin; Tang, Chuan-Dong; Wu, Zhi-Lin; Wang, Wei-Min; Zhang, Yu-Feng; Zhao, Yi; Cravotto, Giancarlo

2015-04-01

This paper presents the purification of eutrophic water using a combination of hydrodynamic cavitation (HC) and ozonation (O3) at a continuous flow of 0.8 m(3) h(-1) on a pilot scale. The maximum removal rate of chlorophyll a using O3 alone and the HC/O3 combination was 62.3 and 78.8%, respectively, under optimal conditions, where the ozone utilization efficiency was 64.5 and 94.8% and total energy consumption was 8.89 and 8.25 kWh m(-3), respectively. Thus, the removal rate of chlorophyll a and the ozone utilization efficiency were improved by 26.5% and 46.9%, respectively, by using the combined technique. Meanwhile, total energy consumption was reduced by 7.2%. Turbidity linearly decreased with chlorophyll a removal rate, but no linear relationship exists between the removal of COD or UV254 and chlorophyll a. As expected, the suction-cavitation-assisted O3 exhibited higher energy efficiency than the extrusion-cavitation-assisted O3 and O3 alone methods.

Electrochemical removal of phenol from oil refinery wastewater.

PubMed

Abdelwahab, O; Amin, N K; El-Ashtoukhy, E-S Z

2009-04-30

This study explores the possibility of using electrocoagulation to remove phenol from oil refinery waste effluent using a cell with horizontally oriented aluminum cathode and a horizontal aluminum screen anode. The removal of phenol was investigated in terms of various parameters namely: pH, operating time, current density, initial phenol concentration and addition of NaCl. Removal of phenol during electrocoagulation was due to combined effect of sweep coagulation and adsorption. The results showed that, at high current density and solution pH 7, remarkable removal of 97% of phenol after 2h can be achieved. The rate of electrocoagulation was observed to increase as the phenol concentration decreases; the maximum removal rate was attained at 30 mg L(-1) phenol concentration. For a given current density using an array of closely packed Al screens as anode was found to be more effective than single screen anode, the percentage phenol removal was found to increase with increasing the number of screens per array. After 2h of electrocoagulation, 94.5% of initial phenol concentration was removed from the petroleum refinery wastewater. Energy consumption and aluminum Electrode consumption were calculated per gram of phenol removed. The present study shows that, electrocoagulation of phenol using aluminum electrodes is a promising process.

Subsurface damage distribution in the lapping process.

PubMed

Wang, Zhuo; Wu, Yulie; Dai, Yifan; Li, Shengyi

2008-04-01

To systematically investigate the influence of lapping parameters on subsurface damage (SSD) depth and characterize the damage feature comprehensively, maximum depth and distribution of SSD generated in the optical lapping process were measured with the magnetorheological finishing wedge technique. Then, an interaction of adjacent indentations was applied to interpret the generation of maximum depth of SSD. Eventually, the lapping procedure based on the influence of lapping parameters on the material removal rate and SSD depth was proposed to improve the lapping efficiency.

Biological treatment of steroidal drug industrial effluent and electricity generation in the microbial fuel cells.

PubMed

Liu, Ru; Gao, Chongyang; Zhao, Yang-Guo; Wang, Aijie; Lu, Shanshan; Wang, Min; Maqbool, Farhana; Huang, Qing

2012-11-01

The single chamber microbial fuel cells (MFCs) were used to treat steroidal drug production wastewater (SPW) and generate electricity simultaneously. The results indicated that the maximum COD removal efficiency reached 82%, total nitrogen and sulfate removal rate approached 62.47% and 26.46%, respectively. The maximum power density and the Coulombic efficiency reached to 22.3Wm(-3) and 30%, respectively. The scanning electron microscope showed that the dominant microbial populations were remarkably different in morphology on the surface of SPW and acetate-fed anodes. PCR-denaturing gradient gel electrophoresis profiles revealed that the microbial community structure fed with different concentrations of SPW presented a gradual succession and unique bacterial sequences were detected on the SPW and acetate-fed anodes. This research demonstrates that MFCs fed with SPW achieved a high efficiency of power density and simultaneous nutrient removal, and the dominant microorganisms on the anode were related to the types and the concentrations of substrates. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparison of phthalic acid removal from aqueous solution by electrochemical methods: Optimization, kinetic and sludge study.

PubMed

Sandhwar, Vishal Kumar; Prasad, Basheshwar

2017-12-01

In this work, comparative study between electrochemical processes such as electrocoagulation (EC), peroxi-coagulation (PC) and peroxi-electrocoagulation (PEC) was performed for the removal of phthalic acid (PA) and chemical oxygen demand (COD) from aqueous medium. Initially, acid treatment was studied at various pH (1-3) and temperature (10-55 °C). Subsequently, the supernatant was re-treated by electrochemical processes such as EC, PC and PEC separately. Independent parameters viz. pH, current density (CD), electrolyte concentration (m), electrode gap (g), H 2 O 2 concentration and electrolysis time (t) were optimized by Central Composite Design (CCD) for these electrochemical processes. All three processes were compared based on removal, energy consumption, kinetic analysis, operating cost and sludge characteristics. In this study, PEC process was found more efficient among EC, PC and PEC processes in order to get maximum removal, minimum energy consumption and minimum operating cost. Maximum removal of PA- 68.21%, 74.36%, 82.25% & COD- 64.79%, 68.15%, 75.21% with energy consumption - 120.95, 97.51, 65.68 (kWh/kg COD removed) were attained through EC, PC and PEC processes respectively at their corresponding optimum conditions. Results indicated that PA and COD removals are in order of PEC > PC > EC under optimum conditions. First order kinetic model was found able to describe the degradation kinetics and provided best correlation for the removal rate within the acceptable error range. Copyright © 2017 Elsevier Ltd. All rights reserved.

Managing the Cayo Santiago rhesus macaque population: The role of density.

PubMed

Hernandez-Pacheco, Raisa; Delgado, Diana L; Rawlins, Richard G; Kessler, Matthew J; Ruiz-Lambides, Angelina V; Maldonado, Elizabeth; Sabat, Alberto M

2016-01-01

Cayo Santiago is the oldest continuously operating free-ranging rhesus monkey colony in the world. Population control of this colony has historically been carried out by periodic live capture and removal of animals. However, the effect of such a strategy on the size, growth rate, age structure, and sex ratio of the population has not been analyzed. This study reviews past removal data and uses a population projection model to simulate the effects of different removal schemes based on Cayo Santiago demographic data from 2000-2012. The model incorporates negative density-dependence in female fertility, as well as male and female survival rates, to determine the population-level effects of selective removal by age and sex. Modeling revealed that removal of sexually immature individuals has negligible effects on the population dynamics explaining why with an initial population of 1309 in 2000 and annual removals of immature monkeys a mean annual population growth rate of 12% and a final population size of ∼1,435 individuals by 2012 (∼0.009 animal/m(2) ) was observed. With no removals, the population is expected to exhibit dampened oscillations until reaching equilibrium at ∼1,690 individuals (∼0.0111 animal/m(2) ) in 2,100. In contrast, removal of adult females (≥4 yrs) would significantly reduce the population size, but would also promote an increase in population growth rate due to density feedback. A maximum annual production of 275 births is expected when 550 adult females are present in the population. Sensitivity analyses showed that removing females, in contrast to controlling their fertility through invasive treatments would contribute the most to changes in population growth rate. Given the density compensation on fertility, stabilizing the population would require removing ∼80% of the current population of adult females. This study highlights the importance of addressing the population-level density effects, as well as sensitivity analyses, to optimize management strategies. © 2016 Wiley Periodicals, Inc.

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.

Nitrogen removal from high organic loading wastewater in modified Ludzack-Ettinger configuration MBBR system.

PubMed

Torkaman, Mojtaba; Borghei, Seyed Mehdi; Tahmasebian, Sepehr; Andalibi, Mohammad Reza

2015-01-01

A moving bed biofilm reactor with pre-denitrification configuration was fed with a synthetic wastewater containing high chemical oxygen demand (COD) and ammonia. By changing different variables including ammonium and COD loading, nitrification rate in the aerobic reactor and denitrification rate in the anoxic reactor were monitored. Changing the influent loading was achieved via adjusting the inlet COD (956-2,096 mg/L), inlet ammonium (183-438 mg/L), and hydraulic retention time of the aerobic reactor (8, 12, and 18 hours). The overall organic loading rate was in the range of 3.60-17.37 gCOD/m2·day, of which 18.5-91% was removed in the anoxic reactor depending on the operational conditions. Considering the complementary role of the aerobic reactor, the overall COD removal was in the range 87.3-98.8%. In addition, nitrification rate increased with influent ammonium loading, the maximum rate reaching 3.05 gNH4/m2·day. One of the most important factors affecting nitrification rate was influent C:N entering the aerobic reactor, by increasing which nitrification rate decreased asymptotically. Nitrate removal efficiency in the anoxic reactor was also controlled by the inlet nitrate level entering the anoxic reactor. Furthermore, by increasing the nitrate loading rate from 0.91 to 3.49 gNO/m3·day, denitrification rate increased from 0.496 to 2.47 gNO/m3·day.

Start-up and stabilization of an Anammox process from a non-acclimatized sludge in CSTR.

PubMed

Bagchi, Samik; Biswas, Rima; Nandy, Tapas

2010-09-01

Development of an Anammox (anaerobic ammonium oxidation) process using non-acclimatized sludge requires a long start-up period owing to the very slow growth rate of Anammox bacteria. This article addresses the issue of achieving a shorter start-up period for Anammox activity in a well-mixed continuously stirred tank reactor (CSTR) using non-acclimatized anaerobic sludge. Proper selection of enrichment conditions and low stirring speed of 30 +/- 5 rpm resulted in a shorter start-up period (82 days). Activity tests revealed the microbial community structure of Anammox micro-granules. Ammonia-oxidizing bacteria (AOB) were found on the surface and on the outer most layers of granules while nitrite-oxidizing bacteria (NOB) and Anammox bacteria were present inside. Fine-tuning of influent NO2(-)/NH4+ ratio allowed Anammox activity to be maintained when mixed microbial populations were present. The maximum nitrogen removal rate achieved in the system was 0.216 kg N/(m(3) day) with a maximum specific nitrogen removal rate of 0.434 g N/(g VSS day). During the study period, Anammox activity was not inhibited by pH changes and free ammonia toxicity.

Coagulation removal of humic acid-stabilized carbon nanotubes from water by PACl: influences of hydraulic condition and water chemistry.

PubMed

Ma, Si; Liu, Changli; Yang, Kun; Lin, Daohui

2012-11-15

Discharged carbon nanotubes (CNTs) can adsorb the widely-distributed humic acid (HA) in aquatic environments and thus be stabilized. HA-stabilized CNTs can find their way into and challenge the potable water treatment system. This study investigated the efficiency of coagulation and sedimentation techniques in the removal of the HA-stabilized multi-walled carbon nanotubes (MWCNTs) using polyaluminum chloride (PACl) as a coagulant, with a focus on the effects of hydraulic conditions and water chemistry. Stirring speeds in the mixing and reacting stages were gradually changed to examine the effect of the hydraulic conditions on the removal rate. The stirring speed in the reacting stage affected floc formation and thereby had a greater impact on the removal rate than the stirring speed in the mixing stage. Water chemistry factors such as pH and ionic strength had a significant effect on the stability of MWCNT suspension and the removal efficiency. Low pH (4-7) was favorable for saving the coagulant and maintaining high removal efficiency. High ionic strength facilitated the destabilization of the HA-stabilized MWCNTs and thereby lowered the required PACl dosage for the coagulation. However, excessively high ionic strength (higher than the critical coagulation concentration) decreased the maximum removal rate, probably by inhibiting ionic activity of PACl hydrolyzate in water. These results are expected to shed light on the potential improvement of coagulation removal of aqueous stabilized MWCNTs in water treatment systems. Copyright © 2012 Elsevier B.V. All rights reserved.

Cultivation of newly isolated microalgae Coelastrum sp. in wastewater for simultaneous CO2 fixation, lipid production and wastewater treatment.

PubMed

Mousavi, Shokouh; Najafpour, Ghasem D; Mohammadi, Maedeh; Seifi, Mohammad Hasan

2018-04-01

Cultivation of microalgae in wastewater is a promising and cost-effective approach for both CO 2 biofixation and wastewater remediation. In this study, a new strain of Coelastrum sp. was isolated from cattle manure leachate. The isolated microalgae were then cultivated in wastewater. Effects of different sCOD concentrations (600, 750, 900, 1050 mg L -1 ) and light intensities (1000, 2300, 4600, 6900 and 10000 Lux) on biomass production, CO 2 consumption rate and nutrient removal from wastewater were investigated. The results showed that maximum cell growth and CO 2 consumption rate were 2.71 g L -1 and 53.12 mg L -1 day -1 , respectively, which were obtained in the wastewater with 750 mg L -1 sCOD and under the light intensity of 6900 Lux. The microalgae were able to completely consume all CO 2 after incubation period of 4 days. The highest sCOD, total Kjeldahl nitrogen (TKN), nitrate and total phosphorous (TP) removal at such conditions were 53.45, 91.18, 87.51 and 100%, respectively. The lipid content of microalgal biomass was also measured under different light intensities; maximum amount of lipid was determined to be 50.77% under illumination of 2300 Lux. Finally, the CO 2 consumption rate and biomass productivity of microalgae in semi-batch culture with continuous gas flow (CO 2 6%:N 2 94%) were investigated. The rate of CO 2 consumption and biomass productivity were 0.528 and 0.281 g L -1 day -1 , respectively. The TKN, nitrate, TP and sCOD removal rate of microalgae were 83.51, 80.91, 100, 41.4%, respectively.

Effects of proton exchange membrane on the performance and microbial community composition of air-cathode microbial fuel cells.

PubMed

Lee, Yun-Yeong; Kim, Tae Gwan; Cho, Kyung-Suk

2015-10-10

This study investigated the effects of proton exchange membranes (PEMs) on performance and microbial community of air-cathode microbial fuel cells (MFCs). Air-cathode MFCs with reactor volume of 1L were constructed in duplicate with or without PEM (designated as ACM-MFC and AC-MFC, respectively) and fed with a mixture of glucose and acetate (1:1, w:w). The maximum power density and coulombic efficiency did not differ between MFCs in the absence or presence of a PEM. However, PEM use adversely affected maximum voltage production and the rate of organic compound removal (p<0.05). Quantitative droplet digital PCR indicated that AC-MFCs had a greater bacterial population than ACM-MFCs (p<0.05). Likewise, ribosomal tag pyrosequencing revealed that the diversity index of bacterial communities was greater for AC-MFCs (p<0.05). Network analysis revealed that the most abundant genus was Enterococcus, which comprised ≥62% of the community and was positively associated with PEM and negatively associated with the rate of chemical oxygen demand (COD) removal (Pearson correlation>0.9 and p<0.05). Geobacter, which is known as an exoelectrogen, was positively associated with maximum power density and negatively associated with PEM. Thus, these results suggest that the absence of PEM favored the growth of Geobacter, a key player for electricity generation in MFC systems. Taken together, these findings demonstrate that MFC systems without PEM are more efficient with respect to power production and COD removal as well as exoelectrogen growth. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of organic matter removal and electricity generation by using integrated microbial fuel cells for wastewater treatment.

PubMed

Yamashita, Takahiro; Ishida, Mitsuyoshi; Ogino, Akifumi; Yokoyama, Hiroshi

2016-01-01

A floating all-in-one type of microbial fuel cell (Fa-MFC) that allows simple operation and installation in existing wastewater reservoirs for decomposition of organic matter was designed. A prototype cell was constructed by fixing a tubular floater to an assembly composed of a proton-exchange membrane and an air-cathode. To compare anode materials, carbon-cloth anodes or carbon-brush anodes were included in the assembly. The fabricated assemblies were floated in 1-L beakers filled with acetate medium. Both reactors removed acetate at a rate of 133-181 mg/L/d. The Fa-MFC quipped with brush anodes generated a 1.7-fold higher maximum power density (197 mW/m(2)-cathode area) than did that with cloth anodes (119 mW/m(2)-cathode area). To evaluate the performance of the Fa-MFCs on more realistic substrates, artificial wastewater, containing peptone and meat extract, was placed in a 2-L beaker, and the Fa-MFC with brush anodes was floated in the beaker. The Fa-MFC removed the chemical oxygen demand of the wastewater at a rate of 465-1029 mg/L/d, and generated a maximum power density of 152 mW/m(2)-cathode area. When the Fa-MFC was fed with actual livestock wastewater, the biological oxygen demand of the wastewater was removed at a rate of 45-119 mg/L/d, with electricity generation of 95 mW/m(2)-cathode area. Bacteria related to Geobacter sulfurreducens were predominantly detected in the anode biofilm, as deduced from the analysis of the 16S rRNA gene sequence.

Adsorptive removal of direct azo dye from aqueous phase onto coal based sorbents: a kinetic and mechanistic study.

PubMed

Venkata Mohan, S; Chandrasekhar Rao, N; Karthikeyan, J

2002-03-01

This communication presents the results pertaining to the investigation conducted on color removal of trisazo direct dye, C.I. Direct Brown 1:1 by adsorption onto coal based sorbents viz. charfines, lignite coal, bituminous coal and comparing results with activated carbon (Filtrasorb-400). The kinetic sorption data indicated the sorption capacity of the different coal based sorbents. The sorption interaction of direct dye on to coal based sorbents obeys first-order irreversible rate equation and activated carbon fits with the first-order reversible rate equation. Intraparticle diffusion studies revealed the dye sorption interaction was complex and intraparticle diffusion was not only the rate limiting step. Isothermal data fit well with the rearranged Langmuir adsorption model. R(L) factor revealed the favorable nature of the isotherm of the dye-coal system. Neutral solution pH yielded maximum dye color removal. Desorption and interruption studies further indicated that the coal based sorbents facilitated chemisorption in the process of dye sorption while, activated carbon resulted in physisorption interaction.

Removal of H2S in down-flow GAC biofiltration using sulfide oxidizing bacteria from concentrated latex wastewater.

PubMed

Rattanapan, Cheerawit; Boonsawang, Piyarat; Kantachote, Duangporn

2009-01-01

A biofiltration system with sulfur oxidizing bacteria immobilized on granular activated carbon (GAC) as packing materials had a good potential when used to eliminate H(2)S. The sulfur oxidizing bacteria were stimulated from concentrated latex wastewater with sulfur supplement under aerobic condition. Afterward, it was immobilized on GAC to test the performance of cell-immobilized GAC biofilter. In this study, the effect of inlet H(2)S concentration, H(2)S gas flow rate, air gas flow rate and long-term operation on the H(2)S removal efficiency was investigated. In addition, the comparative performance of sulfide oxidizing bacterium immobilized on GAC (biofilter A) and GAC without cell immobilization (biofilter B) systems was studied. It was found that the efficiency of the H(2)S removal was more than 98% even at high concentrations (200-4000 ppm) and the maximum elimination capacity was about 125 g H(2)S/m(3)of GAC/h in the biofilter A. However, the H(2)S flow rate of 15-35 l/h into both biofilters had little influence on the efficiency of H(2)S removal. Moreover, an air flow rate of 5.86 l/h gave complete removal of H(2)S (100%) in biofilter A. During the long-term operation, the complete H(2)S removal was achieved after 3-days operation in biofilter A and remained stable up to 60-days.

Visceral adipose tissue modulates mammalian longevity

PubMed Central

Muzumdar, Radhika; Allison, David B.; Huffman, Derek M.; Ma, Xiaohui; Atzmon, Gil; Einstein, Francine H.; Fishman, Sigal; Poduval, Aruna D.; McVei, Theresa; Keith, Scott W.; Barzilai, Nir

2008-01-01

Summary Caloric restriction (CR) can delay many age-related diseases and extend lifespan, while an increase in adiposity is associated with enhanced disease risk and accelerated aging. Among the various fat depots, the accrual of visceral fat (VF) is a common feature of aging, and has been shown to be the most detrimental on metabolic syndrome of aging in humans. We have previously demonstrated that surgical removal of VF in rats improves insulin action; thus, we set out to determine if VF removal affects longevity. We prospectively studied lifespan in three groups of rats: ad libitum-fed (AL-fed), CR (Fed 60% of AL) and a group of AL-fed rats with selective removal of VF at 5 months of age (VF-removed rats). We demonstrate that compared to AL-fed rats, VF-removed rats had a significant increase in mean (p < 0.001) and maximum lifespan (p < 0.04) and significant reduction in the incidence of severe renal disease (p < 0.01). CR rats demonstrated the greatest mean and maximum lifespan (p < 0.001) and the lowest rate of death as compared to AL-fed rats (0.13). Taken together, these observations provide the most direct evidence to date that a reduction in fat mass, specifically VF, may be one of the possible underlying mechanisms of the anti-aging effect of CR. PMID:18363902

Improving bioelectricity generation and COD removal of sewage sludge in microbial desalination cell.

PubMed

Ebrahimi, Atieh; Yousefi Kebria, Daryoush; Darzi, Ghasem Najafpour

2018-05-01

Improving wastewater treatment process and water desalination are two important solutions for increasing the available supply of fresh water. Microbial desalination cells (MDCs) with common electrolytes display relatively low organic matter removal and high cost. In this study, sewage sludge was used as the substrate in the Microbial desalination cell (MDC) under three different initial salt concentrations (5, 20 and 35 g.L -1 ) and the maximum salt removal rates of 50.6%, 64% and 69.6% were obtained under batch condition, respectively. The MDC also produced the maximum power density of 47.1 W m -3 and the averaged chemical oxygen demand (COD) removal of 58.2 ± 0.89% when the initial COD was 6610 ± 83 mg L -1 . Employing treated sludge as catholyte enhanced COD removal and power density to 87.3% and 54.4 W m -3 , respectively, with counterbalancing pH variation in treated effluent. These promising results showed, for the first time, that the excess sewage sludge obtained from biological wastewater treatment plants could be successfully used as anolyte and catholyte in MDC, achieving organic matter biodegradation along with salt removal and energy production. In addition, using treated sludge as catholyte will improve the performance of MDC and introduce a more effective method for both sludge treatment and desalination.

Pilot-scale tertiary MBBR nitrification at 1°C: characterization of ammonia removal rate, solids settleability and biofilm characteristics.

PubMed

Young, Bradley; Delatolla, Robert; Ren, Baisha; Kennedy, Kevin; Laflamme, Edith; Stintzi, Alain

2016-08-01

Pilot-scale moving bed biofilm reactor (MBBR) is used to investigate the kinetics and biofilm response of municipal, tertiary nitrification at 1°C. The research demonstrates that significant rates of tertiary MBBR nitrification are attainable and stable for extended periods of operation at 1°C, with a maximum removal rate of 230 gN/m(3) d at 1°C. At conventional nitrogen loading rates, low ammonia effluent concentrations below 5 mg-N/L were achieved at 1°C. The biofilm thickness and dry weight biofilm mass (massdw) were shown to be stable, with thickness values showing a correlation to the protein/polysaccharide ratio of the biofilm extracellular polymeric substances. Lastly, tertiary MBBR nitrification is shown to increase the effluent suspended solids concentrations by approximately 3 mg total suspended solids /L, with 19-60% of effluent solids being removed after 30 min of settling. The settleability of the effluent solids was shown to be correlated to the nitrogen loading of the MBBR system.

A Leptolyngbya-based microbial consortium for agro-industrial wastewaters treatment and biodiesel production.

PubMed

Tsolcha, Olga N; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Antonopoulou, Georgia; Aggelis, George; Genitsaris, Savvas; Moustaka-Gouni, Maria; Vayenas, Dimitrios V

2018-04-22

A mixed cyanobacterial-mixotrophic algal population, dominated by the filamentous cyanobacterium Leptolyngbya sp. and the microalga Ochromonas (which contributed to the total photosynthetic population with rates of less than 5%), was studied under non-aseptic conditions for its efficiency to remove organic and inorganic compounds from different types of wastes/wastewaters while simultaneously producing lipids. Second cheese whey, poplar sawdust, and grass hydrolysates were used in lab-scale experiments, in photobioreactors that operated under aerobic conditions with different initial nutrient (C, N and P) concentrations. Nutrient removal rates, biomass productivity, and the maximum oil production rates were determined. The highest lipid production was achieved using the biologically treated dairy effluent (up to 14.8% oil in dry biomass corresponding to 124 mg L -1 ) which also led to high nutrient removal rates (up to 94%). Lipids synthesized by the microbial consortium contained high percentages of saturated and mono-unsaturated fatty acids (up to 75% in total lipids) for all the substrates tested, which implies that the produced biomass may be harnessed as a source of biodiesel.

Behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor.

PubMed

Zhang, Xinbo; Song, Zi; Guo, Wenshan; Lu, Yanmin; Qi, Li; Wen, Haitao; Ngo, Huu Hao

2017-12-01

This study aims to investigate the behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor by evaluating nitrification and denitrification rates of sponge biocarriers from three aerobic moving bed biofilm reactors (MBBRs) with filling ratios of 10% (R-10), 20% (R-20) and 30% (R-30). Results showed that the highest removal efficiencies of total nitrogen in three reactors were 84.5% (R-10), 93.6% (R-20) and 95.3% (R-30). Correspondingly, simultaneous nitrification and denitrification rate (SND) was 90.9%, 97.6% and 100%, respectively. Although R-20 had the highest attached-growth biomass (AGB) per gram of sponge compared to the other two reactors, R-30 showed the maximum ammonium oxidation rate (AOR) (2.1826±0.0717mgNH 4 + -N/gAGB/h) and denitrification rate (DNR) (5.0852±0.0891mgNO 3 - -N/gAGB/h), followed by R-20 and R-10. These results indicated AOR, DNR and AGB were affected by the filling ratio under the same operation mode. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimal conditions for bioremediation of oily seawater.

PubMed

Zahed, Mohammad Ali; Aziz, Hamidi Abdul; Isa, Mohamed Hasnain; Mohajeri, Leila; Mohajeri, Soraya

2010-12-01

To determine the influence of nutrients on the rate of biodegradation, a five-level, three-factor central composite design (CCD) was employed for bioremediation of seawater artificially contaminated with crude oil. Removal of total petroleum hydrocarbons (TPH) was the dependent variable. Samples were extracted and analyzed according to US-EPA protocols. A significant (R(2)=0.9645, P<0.0001) quadratic polynomial mathematical model was generated. Removal from samples not subjected to optimization and removal by natural attenuation were 53.3% and 22.6%, respectively. Numerical optimization was carried out based on desirability functions for maximum TPH removal. For an initial crude oil concentration of 1g/L supplemented with 190.21 mg/L nitrogen and 12.71 mg/L phosphorus, the Design-Expert software predicted 60.9% hydrocarbon removal; 58.6% removal was observed in a 28-day experiment. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Dissolved oxygen as a factor influencing nitrogen removal rates in a one-stage system with partial nitritation and Anammox process.

PubMed

Cema, G; Płaza, E; Trela, J; Surmacz-Górska, J

2011-01-01

A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m3), supplied with reject water from the Himmerfjärden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O2 m(-3) At a DO concentration of 4 g O2 m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O2 m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O2 m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.

Removal of Organic Pollutants from Municipal Wastewater by Applying High-Rate Algal Pond in Addis Ababa, Ethiopia

NASA Astrophysics Data System (ADS)

Alemu, Keneni; Assefa, Berhanu; Kifle, Demeke; Kloos, Helmut

2018-05-01

The discharge of inadequately treated municipal wastewater has aggravated the pollution load in developing countries including Ethiopia. Conventional wastewater treatment methods that require high capital and operational costs are not affordable for many developing nations, including Ethiopia. This study aimed to investigate the performance of two high-rate algal ponds (HRAPs) in organic pollutant removal from primary settled municipal wastewater under highland tropical climate conditions in Addis Ababa. The experiment was done for 2 months at hydraulic retention times (HRTs) ranging from 2 to 8 days using an organic loading rates ranging 333-65 kg {BOD}5 /ha/day using two HRAPs, 250 and 300 mm deep, respectively. In this experiment, Chlorella sp., Chlamydomonas sp., and Scenedesmus sp., the class of Chlorophyceae, were identified as the dominant species. Chlorophyll-a production was higher in the shallower ponds (250 mm) throughout the course of the study, whereas the deeper HRAP (300 mm) showed better dissolved oxygen production. The maximum COD and {BOD}5 removal of 78.03 and 81.8% was achieved at a 6-day HRT operation in the 250-mm-deep HRAP. Therefore, the 300-mm-deep HRAP is promising for scaling up organic pollutant removal from municipal wastewater at a daily average organic loading rate of 109.3 kg {BOD}5 /ha/day and a 6-day HRT. We conclude that the removal of organic pollutants in HRAP can be controlled by pond depth, organic loading rate, and HRT.

Hydrocarbon removal from bilgewater by a combination of air-stripping and photocatalysis.

PubMed

Cazoir, D; Fine, L; Ferronato, C; Chovelon, J-M

2012-10-15

In order to prevent hydrocarbon discharge at sea from the bilge of ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which effluents are now limited to those with maximum oil content of 15 ppmv. Thus, photocatalysis and air-stripping were combined for the hydrocarbon removal from a real oily bilgewater sample and an original monitoring of both aqueous and gaseous phases was performed by GC/MS to better understand the process. Our results show that the hydrocarbon oil index [HC] can be reduced to its maximum permissible value of 15 ppmv (MARPOL) in only 8.5h when photocatalysis and air-stripping are used together in a synergistic way, as against 17 h when photocatalysis is used alone. However, this air-assisted photocatalytic process emits a large quantity of volatile organic compounds (VOC) and, within the first four hours, ca. 10% of the hydrocarbon removal in the aqueous phase is actually just transferred into the gaseous one. Finally, we highlight that the n-alkanes with a number of carbon atoms higher than 15 (N(C)>15) are those which most decrease the rate of [HC] removal. Copyright © 2012 Elsevier B.V. All rights reserved.

Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

PubMed

Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

2014-12-01

This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

RAPID NITRATE UPTAKE RATES AND LARGE SHORT-TERM STORAGE CAPACITIES MAY EXPLAIN WHY OPPORTUNISTIC GREEN MACROALGAE DOMINATE SHALLOW EUTROPHIC ESTUARIES1.

PubMed

Kennison, Rachel L; Kamer, Krista; Fong, Peggy

2011-06-01

We quantified the effects of initial macroalgal tissue nitrogen (N) status (depleted and enriched) and varying pulses of nitrate (NO 3 - ) concentration on uptake and storage of nitrogen in Ulva intestinalis L. and Ulva expansa (Setch.) Setch. et N. L. Gardner using mesocosms modeling shallow coastal estuaries in Mediterranean climates. Uptake of NO 3 - (μmol · g dry weight [dwt] -1  · h -1 ) was measured as loss from the water after 1, 2, 4, 8, 12, and 24 h and storage as total tissue nitrogen (% dwt) and nitrate (ppm). Both species of algae exhibited a high affinity for NO 3 - across all N pulses and initial tissue contents. There was greater NO 3 - removal from the water for depleted than enriched algae across all time intervals. In the low-N-pulse treatment, U. intestinalis and U. expansa removed all measurable NO 3 - within 8 and 12 h, respectively, and in the medium and high treatments, removal was high and then decreased over time. Maximum mean uptake rates of nitrate were greater for U. expansa (∼300 μmol · g dwt -1  · h -1 ) than U. intestinalis (∼100 μmol · g dwt -1  · h -1 ); however, uptake rates were highly variable over time. Overall, U. expansa uptake rates were double those of U. intestinalis. Maximum tissue NO 3 - for U. expansa was >1,000 ppm, five times that of U. intestinalis, suggesting that U. expansa has a greater storage capacity in this cellular pool. These results showed that opportunistic green algae with differing tissue nutrient histories were able to efficiently remove nitrate from the water across a wide range of N pulses; thus, both are highly adapted to proliferate in estuarine environments with pulsed nutrient supplies. © 2011 Phycological Society of America.

40 CFR 53.63 - Test procedure: Wind tunnel inlet aspiration test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the sampler inlet opening centered in the sampling zone. To meet the maximum blockage limit of § 53.62(c)(1) or for convenience, part of the test sampler may be positioned external to the wind tunnel... = reference method sampler volumetric flow rate; and t = sampling time. (iii) Remove the reference method...

Kinetic of carbonaceous substrate in an upflow anaerobic sludge sludge blanket (UASB) reactor treating 2,4 dichlorophenol (2,4 DCP).

PubMed

Sponza, Delia Teresa; Uluköy, Ayşen

2008-01-01

The performance of an upflow anaerobic sludge blanket (UASB) reactor treating 2,4 dichlorophenol (2,4 DCP) was evaluated at different hydraulic retention times (HRTs) using synthetic wastewater in order to obtain the growth substrate (glucose-COD) and 2,4 DCP removal kinetics. Treatment efficiencies of the UASB reactor were investigated at different hydraulic retention times (2-20 h) corresponding to a food to mass (F/M) ratio of 1.2-1.92 g-COD g(-1) VSS day(-1). A total of 65-83% COD removal efficiencies were obtained at HRTs of 2-20 h. In all, 83% and 99% 2,4 DCP removals were achieved at the same HRTs in the UASB reactor. Conventional Monod, Grau Second-order and Modified Stover-Kincannon models were applied to determine the substrate removal kinetics of the UASB reactor. The experimental data obtained from the kinetic models showed that the Monod kinetic model is more appropriate for correlating the substrate removals compared to the other models for the UASB reactor. The maximum specific substrate utilization rate (k) (mg-COD mg(-1) SS day(-1)), half-velocity concentration (K(s)) (mg COD l(-1)), growth yield coefficient (Y) (mg mg(-1)) and bacterial decay coefficient (b) (day(-1)) were 0.954 mg-COD mg(-1) SS day(-1), 560.29 mg-COD l(-1), 0.78 mg-SS g(-1)-COD, 0.093 day(-1) in the Conventional Monod kinetic model. The second-order kinetic coefficient (k(2)) was calculated as 0.26 day(-1) in the Grau reaction kinetic model. The maximum COD removal rate constant (U(max)) and saturation value (K(B)) were calculated as 7.502 mg CODl(-1)day(-1) and 34.56 mg l(-1)day(-1) in the Modified Stover-Kincannon Model. The (k)(mg-2,4 DCP mg(-1) SS day(-1)), (K(s)) (mg 2,4 DCPl(-1)), (Y) (mg SS mg(-1) 2,4 DCP) and (k(d)) (day(-1)) were 0.0041 mg-2,4 DCP mg(-1) SS day(-1), 2.06 mg-COD l(-1), 0.0017 mg-SS mg(-1) 2,4 DCP and 3.1 x 10(-5) day(-1) in the Conventional Monod kinetic model for 2,4 DCP degradation. The second-order kinetic coefficient (k(2)) was calculated as 0.30 day(-1) in the Grau reaction kinetic model. The maximum 2,4 DCP removal rate constant (U(max)) and saturation value (K(B)) were calculated as 0.01 mg COD l(-1) day(-1) and 9.8 x 10(-3) mg l(-1) day(-1) in the Modified Stover-Kincannon model.

Optimization of a horizontal-flow biofilm reactor for the removal of methane at low temperatures.

PubMed

Clifford, E; Kennelly, C; Walsh, R; Gerrity, S; Reilly, E O; Collins, G

2012-10-01

Three pilot-scale, horizontal-flow biofilm reactors (HFBRs 1-3) were used to treat methane (CH4)-contaminated air to assess the potential of this technology to manage emissions from agricultural activities, waste and wastewater treatment facilities, and landfills. The study was conducted over two phases (Phase 1, lasting 90 days and Phase 2, lasting 45 days). The reactors were operated at 10 degrees C (typical of ambient air and wastewater temperatures in northern Europe), and were simultaneously dosed with CH4-contaminated air and a synthetic wastewater (SWW). The influent loading rates to the reactors were 8.6 g CH4/m3/hr (4.3 g CH4/m2 TPSA/hr; where TPSA is top plan surface area). Despite the low operating temperatures, an overall average removal of 4.63 g CH4/m3/day was observed during Phase 2. The maximum removal efficiency (RE) for the trial was 88%. Potential (maximum) rates of methane oxidation were measured and indicated that biofilm samples taken from various regions in the HFBRs had mostly equal CH4 removal potential. In situ activity rates were dependent on which part of the reactor samples were obtained. The results indicate the potential of the HFBR, a simple and robust technology, to biologically treat CH4 emissions. The results of this study indicate that the HFBR technology could be effectively applied to the reduction of greenhouse gas emissions from wastewater treatment plants and agricultural facilities at lower temperatures common to northern Europe. This could reduce the carbon footprint of waste treatment and agricultural livestock facilities. Activity tests indicate that methanotrophic communities can be supported at these temperatures. Furthermore, these data can lead to improved reactor design and optimization by allowing conditions to be engineered to allow for improved removal rates, particularly at lower temperatures. The technology is simple to construct and operate, and with some optimization of the liquid phase to improve mass transfer, the HFBR represents a viable, cost-effective solution for these emissions.

Improving the biological nitrogen removal process in pharmaceutical wastewater treatment plants: a case study.

PubMed

Torrijos, M; Carrera, J; Lafuente, J

2004-04-01

The Biological Nitrogen Removal (BNR) process of some pharmaceutical wastewater treatment plants has important operational problems. This study shows that, in order to solve these problems, the design of industrial BNR processes should start by analysing three key parameters: the characteristics of the wastewater load, the determination of the maximum TKN removal rate and the detection of toxic or inhibitory compounds in the wastewater. A case study of this analysis in pharmaceutical wastewater is presented here. In this case, the conventional TKN analytical method does not make an accurate characterisation of the wastewater load because it measures a concentration of 100 mg TKN l(-1) whereas the real concentration, determined with a modified TKN analytical method, is 150-500 mg TKN l(-1). Also, the TKN removal of the treatment system is insufficient in some periods because it falls below legal requirements. This problem might be a consequence of the wrong characterisation of wastewater during the design process. The maximum TKN removal at 27 degrees C (24 mg N g VSS(-1) d(-1) or 197 mg N l(-1) d(-1)) was evaluated in a pilot-scale plant. This value is six times greater than the average NLR applied in the full-scale plant. Finally, some of the components of the wastewater, such as p-phenylenediamine, might have inhibitory or toxic effects on the biological process. P-phenylenediamine causes a large decrease in the nitrification rate. This effect was determined by respirometry. This methodology shows that the effect is mainly inhibitory with a contact time of 30 min and if the contact time is longer, 14 hours, a toxic effect is observed.

Removal of dichloromethane from waste gas streams using a hybrid bubble column/biofilter bioreactor

PubMed Central

2014-01-01

The performance of a hybrid bubble column/biofilter (HBCB) bioreactor for the removal of dichloromethane (DCM) from waste gas streams was studied in continuous mode for several months. The HBCB bioreactor consisted of two compartments: bubble column bioreactor removing DCM from liquid phase and biofilter removing DCM from gas phase. Effect of inlet DCM concentration on the elimination capacity was examined in the DCM concentration range of 34–359 ppm with loading rates ranged from 2.2 to 22.8 g/m3.h and constant total empty bed retention time (EBRT) of 200 s. In the equal loading rates, the elimination capacity and removal efficiency of the biofilter were higher than the corresponding values of the bubble column bioreactor. The maximum elimination capacity of the HBCB bioreactor was determined to be 15.7 g/m3.h occurred in the highest loading rate of 22.8 g/m3.h with removal efficiency of 69%. The overall mineralization portion of the HBCB bioreactor was in the range of 72-79%. The mixed liquor acidic pH especially below 5.5 inhibited microbial activity and decreased the elimination capacity. Inhibitory effect of high ionic strength was initiated in the mixed liquor electrical conductivity of 12.2 mS/cm. This study indicated that the HBCB bioreactor could benefit from advantages of both bubble column and biofilter reactors and could remove DCM from waste gas streams in a better manner. PMID:24406056

Enhancement of nutrient removal from swine wastewater digestate coupled to biogas purification by microalgae Scenedesmus spp.

PubMed

Prandini, Jean Michel; da Silva, Márcio Luís Busi; Mezzari, Melissa Paola; Pirolli, Mateus; Michelon, William; Soares, Hugo Moreira

2016-02-01

This work investigated the effects of swine wastewater-derived biogas on microalgae biomass production and nutrient removal rates from piggery wastewater concomitantly with biogas filtration. Photobioreactors with dominant Scenedesmus spp. were prepared using non-sterile digestate and exposed to different photoperiods. In the presence of biogas and autotrophic conditions microalgae yield of 1.1±0.2 g L(-1) (growth rate of 141.8±3.5 mg L(-1) d(-1)) was obtained leading to faster N-NH3 and P-PO4(3-) assimilation rate of 21.2±1.2 and 3.5±2.5 mg L(-1) d(-1), respectively. H2S up to 3000 ppmv was not inhibitory and completely removed. Maximum CO2 assimilation of 219±4.8 mg L(-1) d(-1) was achieved. Biological consumption of CH4 up to 18% v/v was verified. O2 up to 22% v/v was controlled by adding acetate to exacerbate oxygen demand by microorganisms. Microalgae-based wastewater treatment coupled to biogas purification accelerates nutrient removal concomitantly producing valuable biomass and biomethane. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrooxidation of industrial wastewater containing 1,4-dioxane in the presence of different salts.

PubMed

Barndõk, H; Hermosilla, D; Cortijo, L; Torres, E; Blanco, A

2014-04-01

The treatment of 1,4-dioxane solution by electrochemical oxidation on boron-doped diamond was studied using a central composite design and the response surface methodology to investigate the use of SO4 (2-) and HCO3 (-) as supporting electrolytes considering the applied electric current, initial chemical oxygen demand (COD) value, and treatment time. Two industrial effluents containing bicarbonate alkalinity, one just carrying 1,4-dioxane (S1), and another one including 1,4-dioxane and 2-methyl-1,3-dioxolane (S2), were treated under optimized conditions and subsequently subjected to biodegradability assays with a Pseudomonas putida culture. Electrooxidation was compared with ozone oxidation (O3) and its combination with hydrogen peroxide (O3/H2O2). Regarding the experimental design, the optimal compromise for maximum COD removal at minimum energy consumption was shown at the maximum tested concentrations of SO4 (2-) and HCO3 (-) (41.6 and 32.8 mEq L(-1), respectively) and the maximum selected initial COD (750 mg L(-1)), applying a current density of 11.9 mA cm(-2) for 3.8 h. Up to 98 % of the COD was removed in the electrooxidation treatment of S1 effluent using 114 kWh per kg of removed COD and about 91 % of the COD from S2 wastewater applying 49 kWh per kg of removed COD. The optimal biodegradability enhancement was achieved after 1 h of electrooxidation treatment. In comparison with O3 and O3/H2O2 alternatives, electrochemical oxidation achieved the fastest degradation rate per oxidant consumption unit, and it also resulted to be the most economical treatment in terms of energy consumption and price per unit of removed COD.

Removal of pharmaceuticals in pre-denitrifying MBBR - Influence of organic substrate availability in single- and three-stage configurations.

PubMed

Polesel, Fabio; Torresi, Elena; Loreggian, Luca; Casas, Mònica Escolà; Christensson, Magnus; Bester, Kai; Plósz, Benedek Gy

2017-10-15

Due to the limited efficiency of conventional biological treatment, innovative solutions are being explored to improve the removal of trace organic chemicals in wastewater. Controlling biomass exposure to growth substrate represents an appealing option for process optimization, as substrate availability likely impacts microbial activity, hence organic trace chemical removal. This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs), where biofilm exposure to different organic substrate loading and composition was controlled by reactor staging. A three-stage MBBR and a single-stage reference MBBR (with the same operating volume and filling ratio) were operated under continuous-flow conditions (18 months). Two sets of batch experiments (day 100 and 471) were performed to quantify and compare pharmaceutical removal and denitrification kinetics in the different MBBRs. Experimental results revealed the possible influence of retransformation (e.g., from conjugated metabolites) and enantioselectivity on the removal of selected pharmaceuticals. In the second set of experiments, specific trends in denitrification and biotransformation kinetics were observed, with highest and lowest rates/rate constants in the first (S1) and the last (S3) staged sub-reactors, respectively. These observations were confirmed by removal efficiency data obtained during continuous-flow operation, with limited removal (<10%) of recalcitrant pharmaceuticals and highest removal in S1 within the three-stage MBBR. Notably, biotransformation rate constants obtained for non-recalcitrant pharmaceuticals correlated with mean specific denitrification rates, maximum specific growth rates and observed growth yield values. Overall, these findings suggest that: (i) the long-term exposure to tiered substrate accessibility in the three-stage configuration shaped the denitrification and biotransformation capacity of biofilms, with significant reduction under substrate limitation; (ii) biotransformation of pharmaceuticals may have occurred as a result of cometabolism by heterotrophic denitrifying bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kinetic modeling and thermodynamic study to remove Pb(II), Cd(II), Ni(II) and Zn(II) from aqueous solution using dead and living Azolla filiculoides.

PubMed

Rakhshaee, Roohan; Khosravi, Morteza; Ganji, Masoud Taghi

2006-06-30

Dead Azolla filiculoides can remove Pb(2+),Cd(2+), Ni(2+) and Zn(2+) corresponding to second-order kinetic model. The maximum adsorption capacity (Q(max)) to remove these metal ions by the alkali and CaCl(2)/MgCl(2)/NaCl (2:1:1, molar ratio) activated Azolla from 283 to 313K was 1.431-1.272, 1.173-0.990, 1.365-1.198 and 1.291-0.981mmol/g dry biomass, respectively. Q(max) to remove these heavy metals by the non-activated Azolla at the mentioned temperature range was obtained 1.131-0.977, 1.092-0.921, 1.212-0.931 and 1.103-0.923mmol/g dry biomass, respectively. In order to remove these metal ions by the activated Azolla, the enthalpy change (DeltaH) was -4.403, -4.495, -4.557 and -4.365kcal/mol and the entropy change (DeltaS) was 2.290, 1.268, 1.745 and 1.006cal/molK, respectively. While, to remove these metal ions by the non-activated Azolla, DeltaH was -3.685, -3.766, -3.967 and -3.731kcal/mol and DeltaS was 2.440, 1.265, 1.036 and 0.933cal/molK, respectively. On the other hand, the living Azolla removed these heavy metals corresponding to first-order kinetic model. It was also shown that pH, temperature and photoperiod were effective both on the rate of Azolla growth and the rate of heavy metals uptake during 10 days. It was appeared the use of Ca(NO(3))(2) increased both Azolla growth rate and the rate of heavy metals uptake while the using KNO(3) although increased Azolla growth rate but decreased the rate of heavy metals uptake.

Simultaneous Hydrogen and Methane Production Through Multi-Phase Anaerobic Digestion of Paperboard Mill Wastewater Under Different Operating Conditions.

PubMed

Farghaly, Ahmed; Tawfik, Ahmed

2017-01-01

Multi-phase anaerobic reactor for H 2 and CH 4 production from paperboard mill wastewater was studied. The reactor was operated at hydraulic retention times (HRTs) of 12, 18, 24, and 36 h, and organic loading rates (OLRs) of 2.2, 1.5, 1.1, and 0.75 kg chemical oxygen demand (COD)/m 3  day, respectively. HRT of 12 h and OLR of 2.2 kg COD/m 3  day provided maximum hydrogen yield of 42.76 ± 14.5 ml/g COD removed and volumetric substrate uptake rate (-rS) of 16.51 ± 4.43 mg COD/L h. This corresponded to the highest soluble COD/total COD (SCOD/TCOD) ratio of 56.25 ± 3.3 % and the maximum volatile fatty acid (VFA) yield (Y VFA ) of 0.21 ± 0.03 g VFA/g COD, confirming that H 2 was mainly produced through SCOD conversion. The highest methane yield (18.78 ± 3.8 ml/g COD removed ) and -rS of 21.74 ± 1.34 mgCOD/L h were achieved at an HRT of 36 h and OLR of 0.75 kg COD/m 3  day. The maximum hydrogen production rate (HPR) and methane production rate (MPR) were achieved at carbon to nitrogen (C/N) ratio of 47.9 and 14.3, respectively. This implies the important effect of C/N ratio on the distinction between the dominant microorganism bioactivities responsible for H 2 and CH 4 production.

Algicidal and denitrification characterization of Acinetobacter sp. J25 against Microcystis aeruginosa and microbial community in eutrophic landscape water.

PubMed

Su, Jun Feng; Ma, Min; Wei, Li; Ma, Fang; Lu, Jin Suo; Shao, Si Cheng

2016-06-15

Acinetobacter sp. J25 exhibited good denitrification and high algicidal activity against toxic Microcystis aeruginosa. Response surface methodology (RSM) experiments showed that the maximum algicidal ratio occurred under the following conditions: temperature, 30.46°C; M. aeruginosa density, 960,000cellsmL(-1); and inoculum, 23.75% (v/v). Of these, inoculum produced the maximum effect. In the eutrophic landscape water experiment, 10% bacterial culture was infected with M. aeruginosa cells in the landscape water. After 24days, the removal ratios of nitrate and chlorophyll-a were high, 100% and 87.86%, respectively. The denitrification rate was approximately 0.118mgNO3(-)-N·L(-1)·h(-1). Moreover, the high-throughput sequencing result showed that Acinetobacter sp. J25 was obviously beneficial for chlorophyll-a and nitrate removal performance in the eutrophic landscape water treatment. Therefore, strain J25 is promising for the simultaneous removal of chlorophyll-a and nitrate in the eutrophic landscape water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Confirmation of monod model for biofiltration of styrene vapors from waste flue gas.

PubMed

Dehghanzadeh, Reza; Roshani, Babak; Asadi, Mahzar; Fahiminia, Mohammad; Aslhashemi, Ahmad

2012-01-01

The objective of this research was to investigate the kinetic behavior of the biofil¬tration process for the removal of styrene. A three stage compost based biofilter was inoculated with thickened activated sludge. The reaction order rate constants were obtained from continuous experiments and used as the specific growth rate for the Monod equation. The measured concentration profiles show a linear dependence on the bed height in the biofilter at higher loadings, such as 75 and 45 g m-3 h-1. This is the condition of reaction limitation for a reaction with zero-order kinetics. From the experimental data, maximum elimination capac¬ity (ECmax) was estimated to be 44, 40 and 26 g m-3 h-1 at empty bed retention times (EBRTs) of 120, 60 and 30 s, respectively. However, at lower loadings, the measured concentration profile of the biofilter is one of exponential increase, which is the condition of both reaction and diffusion limitations for a reaction with zero-order kinetics. Maximum elimination capacities found from the experimental results were the same as Monod model predictions. Both the experimental re¬sults and the model predictions showed the influence of EBRT on the removal rate of styrene, particularly for the highest loading rate. In terms of the practical applications of the proposed models have the advantage of being simpler than Monod kinetics and Monod kinetics requires a numerical solution.

Performance of a passively vented field-scale biofilter for the microbial oxidation of landfill methane.

PubMed

Gebert, J; Gröngröft, A

2006-01-01

An upflow biofilter system was operated on a passively vented landfill for the treatment of residual landfill methane. Biofilter methane emissions as a basis for determining methane removal rates were assessed by manual and automated chamber measurements, by measuring methane concentrations in the top layer gaseous phase in combination with gas flow rates, and by evaluating the methane load in the reverse gas flow following the change of landfill gas flux direction as governed by the course of barometric pressure. Methane removal rates were very high with maximum values of 80 g h(-1) m(-3). For the observed cases, the limit of biofilter methane oxidation capacity was not reached and absolute removal rates were thus linearly correlated to the amount of methane entering the filter. The analysis of methane loads flowing back from the biofilter following phases of longer, continuous and non-oscillating landfill gas emission, however, revealed that in these situations biofilter performance is restricted by deficient oxygen supply. At the oxygen-restricted capacity limit, removal rates are influenced by temperature (positively), methane influx (negatively) and flow rate (negatively) as a measure for the displacement of oxygen. These situations, however, account for only 12% of all emission phases. The investigated biofilter capacity, as derived from laboratory analyses of methanotrophic activities, is sufficient to oxidise 62% of the methane load emitted annually. Field and laboratory data provide a stable basis for the dimensioning of filters in future applications.

7 CFR 82.6 - Rate of payment; total payments.

Code of Federal Regulations, 2011 CFR

2011-01-01

... actual 2005 deliveries of clingstone peaches to processors from those acres of clingstone peach trees... minimum of $500 per acre and a maximum of $1,700 per acre. (b) Payment under paragraph (a) of this section will only be made after tree removal has been verified by the staff of the CCPA. (c) The $100 per ton...

7 CFR 82.6 - Rate of payment; total payments.

Code of Federal Regulations, 2014 CFR

2014-01-01

... actual 2005 deliveries of clingstone peaches to processors from those acres of clingstone peach trees... minimum of $500 per acre and a maximum of $1,700 per acre. (b) Payment under paragraph (a) of this section will only be made after tree removal has been verified by the staff of the CCPA. (c) The $100 per ton...

7 CFR 82.6 - Rate of payment; total payments.

Code of Federal Regulations, 2012 CFR

2012-01-01

... actual 2005 deliveries of clingstone peaches to processors from those acres of clingstone peach trees... minimum of $500 per acre and a maximum of $1,700 per acre. (b) Payment under paragraph (a) of this section will only be made after tree removal has been verified by the staff of the CCPA. (c) The $100 per ton...

7 CFR 82.6 - Rate of payment; total payments.

Code of Federal Regulations, 2013 CFR

2013-01-01

... actual 2005 deliveries of clingstone peaches to processors from those acres of clingstone peach trees... minimum of $500 per acre and a maximum of $1,700 per acre. (b) Payment under paragraph (a) of this section will only be made after tree removal has been verified by the staff of the CCPA. (c) The $100 per ton...

Nitrogen Removal over Nitrite by Aeration Control in Aerobic Granular Sludge Sequencing Batch Reactors

PubMed Central

Lochmatter, Samuel; Maillard, Julien; Holliger, Christof

2014-01-01

This study investigated the potential of aeration control for the achievement of N-removal over nitrite with aerobic granular sludge in sequencing batch reactors. N-removal over nitrite requires less COD, which is particularly interesting if COD is the limiting parameter for nutrient removal. The nutrient removal performances for COD, N and P have been analyzed as well as the concentration of nitrite-oxidizing bacteria in the granular sludge. Aeration phase length control combined with intermittent aeration or alternate high-low DO, has proven to be an efficient way to reduce the nitrite-oxidizing bacteria population and hence achieve N-removal over nitrite. N-removal efficiencies of up to 95% were achieved for an influent wastewater with COD:N:P ratios of 20:2.5:1. The total N-removal rate was 0.18 kgN·m−3·d−1. With N-removal over nitrate the N-removal was only 74%. At 20 °C, the nitrite-oxidizing bacteria concentration decreased by over 95% in 60 days and it was possible to switch from N-removal over nitrite to N-removal over nitrate and back again. At 15 °C, the nitrite-oxidizing bacteria concentration decreased too but less, and nitrite oxidation could not be completely suppressed. However, the combination of aeration phase length control and high-low DO was also at 15 °C successful to maintain the nitrite pathway despite the fact that the maximum growth rate of nitrite-oxidizing bacteria at temperatures below 20 °C is in general higher than the one of ammonium-oxidizing bacteria. PMID:25006970

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor.

PubMed

Elmitwalli, Tarek A; Otterpohl, Ralf

2007-03-01

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).

Cultivation of Chlorella protothecoides with urban wastewater in continuous photobioreactor: biomass productivity and nutrient removal.

PubMed

Ramos Tercero, E A; Sforza, E; Morandini, M; Bertucco, A

2014-02-01

The capability to grow microalgae in nonsterilized wastewater is essential for an application of this technology in an actual industrial process. Batch experiments were carried out with the species in nonsterilized urban wastewater from local treatment plants to measure both the algal growth and the nutrient consumption. Chlorella protothecoides showed a high specific growth rate (about 1 day(-1)), and no effects of bacterial contamination were observed. Then, this microalgae was grown in a continuous photobioreactor with CO₂-air aeration in order to verify the feasibility of an integrated process of the removal of nutrient from real wastewaters. Different residence times were tested, and biomass productivity and nutrients removal were measured. A maximum of microalgae productivity was found at around 0.8 day of residence time in agreement with theoretical expectation in the case of light-limited cultures. In addition, N-NH₄ and P-PO₄ removal rates were determined in order to model the kinetic of nutrients uptake. Results from batch and continuous experiments were used to propose an integrated process scheme of wastewater treatment at industrial scale including a section with C. protothecoides.

Thermophilic biofilter for SO2 removal: performance and microbial characteristics.

PubMed

Zhang, Jingying; Li, Lin; Liu, Junxin

2015-03-01

A bench-scale thermophilic biofilter was applied to remove SO2 at 60°C in the present study. The SO2 concentration in the inlet stream ranged from 100mg/m(3) to 200mg/m(3). An average SO2 removal efficiency of 93.10% was achieved after developing acclimated organisms that can degrade SO2. The thermophilic biofilter effectively reduced SO2, with a maximum elimination capacity of 50.67g/m(3)/h at a loading rate of 51.44g/m(3)/h. Removal efficiency of the thermophilic biofilter was largely influenced by the water containing rate of the packing materials. The SO2 transfer in the biofilter included adsorption by the packing materials, dissolution in liquid, and microbial degradation. The main product of SO2 degradation was SO4(2-). The temporal shifts in the bacterial community that formed in the biofilter were determined through polymerase chain reaction-denaturing gradient gel electrophoresis and DNA sequence analysis. These shifts revealed a correlation between biofilter performance and bacterial community structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Etching of Silicon in HBr Plasmas for High Aspect Ratio Features

NASA Technical Reports Server (NTRS)

Hwang, Helen H.; Meyyappan, M.; Mathad, G. S.; Ranade, R.

2002-01-01

Etching in semiconductor processing typically involves using halides because of the relatively fast rates. Bromine containing plasmas can generate high aspect ratio trenches, desirable for DRAM and MEMS applications, with relatively straight sidewalk We present scanning electron microscope images for silicon-etched trenches in a HBr plasma. Using a feature profile simulation, we show that the removal yield parameter, or number of neutrals removed per incident ion due to all processes (sputtering, spontaneous desorption, etc.), dictates the profile shape. We find that the profile becomes pinched off when the removal yield is a constant, with a maximum aspect ratio (AR) of about 5 to 1 (depth to height). When the removal yield decreases with increasing ion angle, the etch rate increases at the comers and the trench bottom broadens. The profiles have ARs of over 9:1 for yields that vary with ion angle. To match the experimentally observed etched time of 250 s for an AR of 9:1 with a trench width of 0.135 microns, we find that the neutral flux must be 3.336 x 10(exp 17)sq cm/s.

Removal of arsenic from drinking water using rice husk

NASA Astrophysics Data System (ADS)

Asif, Zunaira; Chen, Zhi

2017-06-01

Rice husk adsorption column method has proved to be a promising solution for arsenic (As) removal over the other conventional methods. The present work investigates the potential of raw rice husk as an adsorbent for the removal of arsenic [As(V)] from drinking water. Effects of various operating parameters such as diameter of column, bed height, flow rate, initial arsenic feed concentration and particle size were investigated using continuous fixed bed column to check the removal efficiency of arsenic. This method shows maximum removal of As, i.e., 90.7 % under the following conditions: rice husk amount 42.5 g; 7 mL/min flow rate in 5 cm diameter column at the bed height of 28 cm for 15 ppb inlet feed concentration. Removal efficiency was increased from 83.4 to 90.7 % by reducing the particle size from 1.18 mm to 710 µm for 15 ppb concentration. Langmuir and Freundlich isotherm models were employed to discuss the adsorption behavior. The effect of different operating parameters on the column adsorption was determined using breakthrough curves. In the present study, three kinetic models Adam-Bohart, Thomas and Yoon-Nelson were applied to find out the saturated concentration, fixed bed adsorption capacity and time required for 50 % adsorbate breakthrough, respectively. At the end, solidification was done for disposal of rice husk.

Electrochemically-induced reduction of nitrate in aqueous solution

PubMed Central

Rajic, Lj.; Berroa, D.; Gregor, S.; Elbakri, S.; MacNeil, M.; Alshawabkeh, A.N.

2018-01-01

In this study, we evaluated the removal of nitrate from synthetic groundwater by a cathode followed by an anode electrode sequence in the electrochemical flow-through reactor. We also tested the feasibility of the used electrode sequence to minimize the production of ammonia during the nitrate reduction. The performance of monometallic Fe, Cu, Ni and carbon foam cathodes was tested under different current intensities, flow rates/regimes and the presence of Pd and Ag catalyst coating. With the use of monometallic Fe and an increase in current intensity from 60 mA to 120 mA, the nitrate removal rate increased from 7.6% to 25.0%, but values above 120 mA caused a decrease in removal due to excessive gas formation at the electrodes. Among tested materials, monometallic Fe foam cathode showed the highest nitrates removal rate and increased significantly in the presence of Pd catalyst: from 25.0% to 39.8%. Further, the circulation under 3 mL min−1 elevated the nitrate removal by 33% and the final nitrate concentration fell below the maximum contaminant level of 10 mg L−1 nitrate–nitrogen (NO3-N). During the treatment, the yield of ammonia production after the cathode was 92±4% while after the anode (Ti/IrO2/Ta2O5), the amount of ammonia significantly declined to 50%. The results proved that flow-through, undivided electrochemical systems can be used to remove nitrate from groundwater with the possibility of simultaneously controlling the generation of ammonia. PMID:29657554

Uptake and biotransformation of 2,4,6-trinitrotoluene (TNT) by microplantlet suspension culture of the marine red macroalga Portieria hornemannii.

PubMed

Cruz-Uribe, Octavio; Rorrer, Gregory L

2006-02-20

Microplantlets of the marine red macroalga Portieria hornemannii efficiently removed the explosive compound 2,4,6-trinitrotoluene (TNT) from seawater. Photosynthetic, axenic microplantlets (1.2 g FW/L) were challenged with enriched seawater medium containing dissolved TNT at concentrations of 1.0, 10, and 50 mg/L. At 22 degrees C and initial TNT concentrations of 10 mg/L or less, TNT removal from seawater was 100% within 72 h, and the first-order rate constant for TNT removal ranged from 0.025 to 0.037 L/gFW h under both illuminated conditions (153 microE/m(2)s, 14:10 LD photoperiod) and dark conditions. Two immediate products of TNT biotransformation, 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dintrotoluene, were identified in the liquid culture medium, with a maximum material balance recovery of 29 mole%. Only trace levels of these products and residual TNT were found within the fresh cell biomass. Removal of TNT by P. hornemannii microplantlets at initial concentrations of 1.0 or 10 mg/L did not affect the respiration rate. At an initial TNT concentration of 10 mg/L, net photosynthesis decreased towards zero, commensurate with the removal of dissolved TNT from seawater, whereas at an initial TNT concentration of 1.0 mg/L, the net photosynthesis rate was not affected. Copyright 2005 Wiley Periodicals, Inc.

Removal of natural hormones in dairy farm wastewater using reactive and sorptive materials.

PubMed

Cai, Kai; Phillips, Debra H; Elliott, Christopher T; Muller, Marc; Scippo, Marie-Louise; Connolly, Lisa

2013-09-01

The objective of this study was to examine the oestrogen and androgen hormone removal efficiency of reactive (Connelly zero-valent iron (ZVI), Gotthart Maier ZVI) and sorptive (AquaSorb 101 granular activated carbon (GAC) and OrganoLoc PM-100 organoclay (OC)) materials from HPLC grade water and constructed wetland system (CWS) treated dairy farm wastewater. Batch test studies were performed and hormone concentration analysis carried out using highly sensitive reporter gene assays (RGAs). The results showed that hormonal interaction with these materials is selective for individual classes of hormones. Connelly ZVI and AquaSorb 101 GAC were more efficient in removing testosterone (Te) than 17β-estradiol (E2) and showed faster removal rates of oestrogen and androgen than the other materials. Gotthart Maier ZVI was more efficient in removing E2 than Te. OrganoLoc PM-100 OC achieved the lowest final concentration of E2 equivalent (EEQ) and provided maximum removal of both oestrogens and androgens. Copyright © 2013 Elsevier B.V. All rights reserved.

A continuous flow MFC-CW coupled with a biofilm electrode reactor to simultaneously attenuate sulfamethoxazole and its corresponding resistance genes.

PubMed

Li, Hua; Song, Hai-Liang; Yang, Xiao-Li; Zhang, Shuai; Yang, Yu-Li; Zhang, Li-Min; Xu, Han; Wang, Ya-Wen

2018-05-08

A continuous flow microbial fuel cell constructed wetland (MFC-CW) coupled with a biofilm electrode reactor (BER) system was constructed to remove sulfamethoxazole (SMX). The BER unit powered by the stacked MFC-CWs was used as a pretreatment unit, and effluent flowed into the MFC-CW for further degradation. The experimental results indicated that the removal rate of 2 or 4 mg/L SMX in a BER unit was nearly 90%, and the total removal rate in the coupled system was over 99%. As the hydraulic retention time (HRT) was reduced from 16 h to 4 h, the SMX removal rate in the BER decreased from 75% to 48%. However, the total removal rate in the coupled system was still over 97%. The maximum SMX removal rate in the MFC-CW, which accounted for 42%-55% of the total removal, was obtained in the anode layer. In addition, the relative abundances of sul genes detected in the systems were in the order of sulI > sulII > sulIII, and significant positive correlations of sul gene copy numbers versus SMX concentration and 16S rRNA gene copy numbers were observed. Furthermore, significant negative correlations were identified between sul genes, 16S rRNA gene copy numbers, and HRT. The abundances of the sul genes in the effluent of the MFC-CW were lower than the abundances observed in the BER effluent. High-throughput sequencing revealed that the microbial community diversity of the BER was affected by running time, power supply forms and HRT. Bio-electricity from the MFC-CW may reduce microbial community diversity and contribute to reduction of the antibiotic resistance gene (ARG) abundance in the BER. Taken together, the BER-MFC-CW coupled system is a potential tool to treat wastewater containing SMX and attenuate corresponding ARG abundance. Copyright © 2018 Elsevier B.V. All rights reserved.

Anaerobic co-digestion of vegetable waste and swine wastewater in high-rate horizontal reactors with fixed bed.

PubMed

Mazareli, Raissa Cristina da Silva; Duda, Rose Maria; Leite, Valderi Duarte; Oliveira, Roberto Alves de

2016-06-01

Considering the high waste generation that comes from agriculture and livestock farming, as well as the demand for natural gas, it is necessary to develop sustainable technologies which can reduce environmental impact. There is no available literature on the use of high-rate horizontal anaerobic reactors with fixed bed (HARFB) and continuous feed for the co-digestion of vegetable wastes (VW) and swine wastewater (SW). The aim of this work was to evaluate the reactor performance in terms of methane production, organic matter consumption, and removal of total and thermotolerant coliforms under different proportions of SW and VW, and organic loading rates (OLR) of 4.0, 5.2 and 11.0g COD (Ld)(-)(1). The mixture of SW and VW in the proportions of 90:10, 80:20 and 70:30 (SW:VW) with those OLRs provided great buffering capacity, with partial alkalinity reaching 3552mgL(-1), thereby avoiding the inhibition of methane production by volatile fatty acids produced during the fermentation process. Higher proportions of VW and higher OLR improved volumetric methane production with a maximum value of 1.08LCH4 (Ld)(-)(1), organic matter removal rates up to 98% and total and thermotolerant coliform removal rates of 99% were also observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Heitkamp, M.A.; Adams, W.J.; Camel, V.

Immobilized bacteria technology (IBT) utilizes inert biocarriers to support high concentrations of chemical-degrading bacteria in reactors designed to provide optimal conditions for microbial activity. This study evaluated IBT performance inpacked bed reactors (PBRs) using a porous inorganic biocarrier (diatomaceous earth), nonporous biocarriers (glass beads), and organic biocarriers having carbon adsorption properties (granular activated carbon) with different porosity. Each reactor was challenged with high chemical loading, acid, dryness, and heat shock conditions. Benchtop PBSs inoculated with a p-nitrophenol (PNP)-degrading Pseudomonas sp. and fed a synthetic waste containing 100 to 1,300 mg/L of PNP showed removal of PNP from effluents within 24more » h of start-up. Chemical loading studies showed maximum PNP removal rates of 6.45 to 7.35 kg/m[sup 3]/d for bacteria in PBRs containing diatomaceous earth beads, glass beads, and activated coconut carbon. A lower PNP removal rate of 1.47 kg/m[sup 3]/d was determined for the activated anthracite carbon, and this PBR responded more slowly to increases in chemical loading. The PBR containing bacteria immobilized on activated coconut carbon showed exceptional tolerance to acid shocking, drying, and heat shocking by maintaining PNP removal rates > 85% throughout the entire study. The other biocarriers showed nearly complete loss of PNP degradation during the perturbations, but all recovered high rates of PNP degradation (> 98% removal) within 48 h after an acid shock at pH2, within 8 d after an acid shock at pH 1.0, within 24 h after drying for 72 h, and within 48 h of heat shocking. The resiliency and high chemical removal efficiency demonstrated by immobilized bacteria in this study support the concept of using IBT for the biotreatment of industrial wastes..« less

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.

The effectiveness of stand alone air cleaners for shelter-in-place.

PubMed

Ward, M; Siegel, J A; Corsi, R L

2005-04-01

Stand-alone air cleaners may be efficient for rapid removal of indoor fine particles and have potential use for shelter-in-place (SIP) strategies following acts of bioterrorism. A screening model was employed to ascertain the potential significance of size-resolved particle (0.1-2 microm) removal using portable high efficiency particle arresting (HEPA) air cleaners in residential buildings following an outdoor release of particles. The number of stand-alone air cleaners, air exchange rate, volumetric flow rate through the heating, ventilating and air-conditioning (HVAC) system, and size-resolved particle removal efficiency in the HVAC filter were varied. The effectiveness of air cleaners for SIP was evaluated in terms of the outdoor and the indoor particle concentration with air cleaner(s) relative to the indoor concentration without air cleaners. Through transient and steady-state analysis of the model it was determined that one to three portable HEPA air cleaners can be effective for SIP following outdoor bioaerosol releases, with maximum reductions in particle concentrations as high as 90% relative to conditions in which an air cleaner is not employed. The relative effectiveness of HEPA air cleaners vs. other removal mechanisms was predicted to decrease with increasing particle size, because of increasing competition by particle deposition with indoor surfaces and removal to HVAC filters. However, the effect of particle size was relatively small for most scenarios considered here. The results of a screening analysis suggest that stand-alone (portable) air cleaners that contain high efficiency particle arresting (HEPA) filters can be effective for reducing indoor fine particle concentrations in residential dwellings during outdoor releases of biological warfare agents. The relative effectiveness of stand-alone air cleaners for reducing occupants' exposure to particles of outdoor origin depends on several factors, including the type of heating, ventilating and air-conditioning (HVAC) filter, HVAC operation, building air exchange rate, particle size, and duration of elevated outdoor particle concentration. Maximum particle reductions, relative to no stand-alone air cleaners, of 90% are predicted when three stand-alone air cleaners are employed.

Enrichment of denitrifying methanotrophic bacteria from municipal wastewater sludge in a membrane bioreactor at 20°C.

PubMed

Kampman, Christel; Temmink, Hardy; Hendrickx, Tim L G; Zeeman, Grietje; Buisman, Cees J N

2014-06-15

Simultaneous nitrogen and methane removal by the slow growing denitrifying methanotrophic bacterium 'Candidatus Methylomirabilis oxyfera' offers opportunities for a new approach to wastewater treatment. However, volumetric nitrite consumption rates should be increased by an order of magnitude before application in wastewater treatment becomes possible. A maximum volumetric nitrite consumption rate of 36 mg NO2(-)-N/L d was achieved in a membrane bioreactor inoculated with wastewater sludge and operated at 20°C. This rate is similar to maximum rates reported in literature, though it was thought that by strict biomass retention using membranes, higher rates would be achieved. In experiments lasting several years, growth was not stable: every experiment showed a decrease in activity after 1-2 years. The cause remains unknown. Rates increased after addition of copper and operating a membrane bioreactor at shorter hydraulic retention times. Further research should focus on long-term effects of copper addition and operation at hydraulic retention times in the order of hours using membrane bioreactors. Copyright © 2014 Elsevier B.V. All rights reserved.

Biosorption of Copper (II) from Aqueous Solution Using Non-Living Mesorhizobium amorphae Strain CCNWGS0123

PubMed Central

Mohamad, Osama Abdalla; Hao, Xiuli; Xie, Pin; Hatab, Shaimaa; Lin, Yanbing; Wei, Gehong

2012-01-01

The mining industry generates huge amounts of wastewater, containing toxic heavy metals. Treatment to remove heavy metals is necessary and recent work has been focused on finding more environmentally friendly materials for removing heavy metals from wastewater. Biosorption can be an effective process for heavy metal removal from aqueous solutions. Our objectives were to investigate the removal of copper (II) from aqueous solutions using dead cells of Mesorhizobium amorphae CCNWGS0123 under differing levels of pH, agitation speed, temperature, initial copper concentration, biosorbent dose and contact time using flame atomic absorption spectroscopy for metal estimation. The maximum copper removal rate was achieved at pH 5.0, agitation speed 150×g, temperature 28°C and initial Cu (II) concentration of 100 mg L−1. Maximum biosorption capacity was at 0.5 g L−1 and equilibrium was attained within 30 min. Langmuir and Freundlich isotherms showed correlation coefficients of 0.958 and 0.934, respectively. Fourier transform-infrared spectroscopy (FT-IR) analysis indicated that many functional groups, such as O-H, N-H, C-H, C=O, -NH, -CN, C-N, C-O, amide -I, -II, -III and unsaturated alkenes, alkyls and aromatic groups on the cell surface were involved in the interaction between CCNWGS0123 and Cu. Scanning electron microscope and energy dispersive X-ray scanning results showed deformation, aggregation, and cell-surface damage due to the precipitation of copper on the cell surface. Dead cells of CCNWGS0123 showed potential as an efficient biosorbent for the removal of Cu2+ from aqueous solutions. PMID:22353770

A comparative study of the treatment of ethylene plant spent caustic by neutralization and classical and advanced oxidation.

PubMed

Hawari, Alaa; Ramadan, Hasanat; Abu-Reesh, Ibrahim; Ouederni, Mabrouk

2015-03-15

The treatment of spent caustic produced from an ethylene plant was investigated. In the case of neutralization alone it was found that the maximum removal of sulfide was at pH values below 5.5. The higher percentage removal of sulfides (99% at pH = 1.5) was accompanied with the highest COD removal (88%). For classical oxidation using H2O2 the maximum COD removal percentage reached 89% at pH = 2.5 and at a hydrogen peroxide concentration of 19 mM/L. For the advanced oxidation using Fenton's process it was found that the maximum COD removal of 96.5% was achieved at a hydrogen peroxide/ferrous sulfate ratio of (7:1). Copyright © 2014 Elsevier Ltd. All rights reserved.

Confirmation of Monod Model for Biofiltration of Styrene Vapors from Waste Flue Gas

PubMed Central

Dehghanzadeh, Reza; Roshani, Babak; Asadi, Mahzar; Fahiminia, Mohammad; AslHashemi, Ahmad

2012-01-01

Background: The objective of this research was to investigate the kinetic behavior of the biofil¬tration process for the removal of styrene. Methods: A three stage compost based biofilter was inoculated with thickened activated sludge. The reaction order rate constants were obtained from continuous experiments and used as the specific growth rate for the Monod equation. Results: The measured concentration profiles show a linear dependence on the bed height in the biofilter at higher loadings, such as 75 and 45 g m-3 h-1. This is the condition of reaction limitation for a reaction with zero-order kinetics. From the experimental data, maximum elimination capac¬ity (ECmax) was estimated to be 44, 40 and 26 g m-3 h-1 at empty bed retention times (EBRTs) of 120, 60 and 30 s, respectively. However, at lower loadings, the measured concentration profile of the biofilter is one of exponential increase, which is the condition of both reaction and diffusion limitations for a reaction with zero-order kinetics. Maximum elimination capacities found from the experimental results were the same as Monod model predictions. Both the experimental re¬sults and the model predictions showed the influence of EBRT on the removal rate of styrene, particularly for the highest loading rate. Conclusion: In terms of the practical applications of the proposed models have the advantage of being simpler than Monod kinetics and Monod kinetics requires a numerical solution. PMID:24688940

In vitro rapid intraoral adjustment of porcelain prostheses using a high-speed dental handpiece.

PubMed

Song, Xiao-Fei; Yin, Ling; Han, Yi-Gang; Wang, Hui

2008-03-01

In vitro rapid intraoral adjustment of porcelain prostheses was conducted using a high-speed dental handpiece and diamond bur. The adjustment process was characterized by measurement of removal forces and energy, with scanning electron microscopic (SEM) observation of porcelain debris, surfaces and subsurface damage produced as a function of operational feed rate. Finite element analysis (FEA) was applied to evaluate subsurface stress distributions and degrees of subsurface damage. The results show that an increase in feed rate resulted in increases in both tangential and normal forces (analysis of variance (ANOVA), P<0.01). When the feed rate approached the highest rate of 60mm min(-1) at a fixed depth of cut of 100microm, the tangential force was nearly seven times that at the lowest feed rate of 15mm min(-1). Consequently, the specific removal energy increased significantly (ANOVA, P<0.01), and the maximum depth of subsurface damage obtained was approximately 110 and 120microm at the highest feed rate of 60mm min(-1) using SEM and FEA, respectively. The topographies of both the adjusted porcelain surfaces and the debris demonstrate microscopically that porcelain was removed via brittle fracture and plastic deformation. Clinicians must be cautious when pursuing rapid dental adjustments, because high operational energy, larger forces and severe surface and subsurface damage can be induced.

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.

Study the adsorption of sulfates by high cross-linked polystyrene divinylbenzene anion-exchange resin

NASA Astrophysics Data System (ADS)

Fathy, Mahmoud; Moghny, Th. Abdel; Awadallah, Ahmed E.; El-Bellihi, Abdel-Hameed A.-A.

2017-03-01

In response to rising concerns about the effect of sulfate on water quality, human health, and agriculture, many jurisdictions around the world are imposing tighter regulations for sulfate discharge. This is driving the need for environmental compliance in industries like mining, metal processing, pulp and paper, sewage treatment, and chemical manufacturing. The sulfate removal from synthetic water by high cross-linked polystyrene divinylbenzene resin was studied at batch experiments in this study. The effect of pH, contact time, sulfates concentration, and adsorbent dose on the sulfate sequestration was investigated. The optimum conditions were studied on Saline water as a case study. The results showed that with increasing of the absorbent amount; contact time, and pH improve the efficiency of sulfate removal. The maximum sulfates uptake was obtained in pH and contact time 3.0 and 120 min, respectively. Also, with increasing initial concentration of sulfates in water, the efficiency of sulfate removal decreased. The obtained results in this study were matched with Freundlich isotherm and pseudo-second-order kinetic. The maximum adsorption capacity (Qm) and constant rate were found 0.318 (mg/g) and 0.21 (mg/g.min), respectively. This study also showed that in the optimum conditions, the sulfate removal efficiency from Saline water by 0.1 mg/L sulfates was 65.64 %. Eventually, high cross-linked polystyrene divinylbenzene resin is recommended as a suitable and low cost absorbent to sulfate removal from aqueous solutions.

Sediment retention in a bottomland hardwood wetland in Eastern Arkansas

USGS Publications Warehouse

Kleiss, B.A.

1996-01-01

One of the often-stated functions of wetlands is their ability to remove sediments and other particulates from water, thus improving water quality in the adjacent aquatic system. However, actual rates of suspended sediment removal have rarely been measured in freshwater wetland systems. To address this issue, suspended sediment dynamics were measured in a 85-km2 bottomland hardwood (BLH) wetland adjacent to the highly turbid Cache River in eastern Arkansas during the 1988-1990 water years. A suspended sediment mass balance was calculated using depth-integrated, flow-weighted daily measurements at wetland inflow and outflow points. Over the three-year period, suspended sediment load decreased an average of 14% between upstream and downstream sampling points. To test the idea that the suspended sediments were retained by the adjacent wetland and to determine what portion of the BLH forest was most responsible for retaining the suspended sediments, concurrent measurements of sediment accretion were made at 30 sites in the wetland using feldspar clay marker horizons, sedimentation disks, the 137cesium method, and dendrogeomorphic techniques. Sedimentation rates exceeding 1 cm/yr were measured in frequently flooded areas dominated by Nyssa aquatica and Taxodium distichum. Maximum sedimentation rates did not occur on the natural levee, as would be predicted by classical fluvial geomorphology, but in the "first bottom," where retention time of the water reached a maximum. Multiple regression was used to relate sedimentation rates with several physical and biological factors. A combination of distance from the river, flood duration, and tree basal area accounted for nearly 90% of the variation in sedimentation rates.

Low temperature MBBR nitrification: Microbiome analysis.

PubMed

Young, Bradley; Delatolla, Robert; Kennedy, Kevin; Laflamme, Edith; Stintzi, Alain

2017-03-15

This study aims to investigate post carbon removal moving bed biofilm reactor (MBBR) nitrification through the transition from 20 °C to 1 °C and during through long term operation at 1 °C. Four pilot nitrifying MBBR reactors were operated at various ammonia loading rates to elucidate the temperature effects on ammonia removal rates, cell viability and bacterial communities. The transition from 20 °C to 1 °C and during long term operation at 1 °C were modeled using Arrhenius temperature correction coefficients. Specifically, the steady state removal rates at 1 °C on average were 22.8% of the maximum ammonia removal rate at 20 °C, which corresponds to an Arrhenius temperature correction of 1.086 during steady operation at 1 °C. The microbial communities of the nitrifying MBBR biofilm were shown to be significantly more diverse at 20 °C as compared to 1 °C operation. Although less diverse at 1 °C, 2000 species of bacteria were identified in the nitrifying biofilm during operation at this low temperature. Nitrosomonads were shown to be the dominant ammonia oxidizing bacteria (AOB) and Nitrospira was shown to be the dominant nitrite oxidizing bacteria (NOB) in all the pilot MBBR reactors at all temperatures. The performance of the post carbon removal nitrifying MBBR systems were shown to be enhanced at 1 °C by an increase in the viable embedded biomass as well as thicker biofilm. This effectively increases the number of viable cell present during low temperature operation, which partially compensates for the significant decrease in rate of ammonia removal per nitrifying cell. Operation at the highest loading conditions tested in this study at 1 °C were shown to reduce the ammonia removal rate compared to lower loading conditions at 1 °C. The lower performance at higher loading conditions at 1 °C demonstrated an enrichment in the stress response metagenomics pathways of the system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous carbon and nitrogen removal using a litre-scale upflow microbial fuel cell.

PubMed

Zhao, Ling-ling; Song, Tian-shun

2014-01-01

A 10 L upflow microbial fuel cell (UMFC) was constructed for simultaneous carbon and nitrogen removal. During the 6-month operation, the UMFC constantly removed carbon and nitrogen, and then generated electricity with synthetic wastewater as substrate. At 5.0 mg L(-1) dissolved oxygen, 100 Ω external resistance, and pH 6.5, the maximum power density (Pmax) and nitrification rate for the UMFC was 19.5 mW m(-2) and 17.9 mg·(L d)(-1), respectively. In addition, Pmax in the UMFC with chicken manure wastewater as substrate was 16 mW m(-2), and a high chemical oxygen demand (COD) removal efficiency of 94.1% in the UMFC was achieved at 50 mM phosphate-buffered saline. Almost all ammonia in the cathode effluent was effectively degraded after biological denitrification in the UMFC cathode. The results can help to further develop pilot-scale microbial fuel cells for simultaneous carbon and nitrogen removal.

Nitrogen-removal efficiency of a novel aerobic denitrifying bacterium, Pseudomonas stutzeri strain ZF31, isolated from a drinking-water reservoir.

PubMed

Huang, Tinglin; Guo, Lin; Zhang, Haihan; Su, Junfeng; Wen, Gang; Zhang, Kai

2015-11-01

An aerobic denitrifier, identified as Pseudomonas stutzeri strain ZF31, was isolated from the Zhoucun drinking-water reservoir. Strain ZF31 removed 97% of nitrate nitrogen after 16h, without nitrite accumulation. Sequence amplification indicated the presence of the denitrification genes napA, nirS, norB, and nosZ. Nitrogen balance analysis revealed that approximately 75% of the initial nitrogen was removed as gas products. Response surface methodology (RSM) experiments showed that maximum removal of total nitrogen (TN) occurred at pH 8.23, a C/N ratio of 6.68, temperature of 27.72°C, and with shaking at 54.15rpm. The TN removal rate at low C/N ratio (i.e., 3) and low temperature (i.e., 10°C) was 73.30% and 60.08%, respectively. These results suggest that strain ZF31 has potential applications for the bioremediation of slightly polluted drinking-water reservoirs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Membrane bioreactor treatment of a simulated metalworking fluid wastewater containing ethylenediaminetetraacetic acid and dicyclohexylamine.

PubMed

Anderson, James E; Lofton, Tiffany V; Kim, Byung R; Mueller, Sherry A

2009-04-01

Membrane bioreactors (MBRs) have been installed at automotive plants to treat metalworking fluid (MWF) wastewaters, which are known to contain toxic and/or recalcitrant organic compounds. A laboratory study was conducted to evaluate treatment of a simulated wastewater prepared from a semisynthetic MWF, which contains two such compounds, dicyclohexylamine (DCHA) and ethylenediaminetetraacetic acid (EDTA). Primary findings were as follows: During stable operating periods, almost all chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), and EDTA were removed (by > 96%). During somewhat unstable periods, COD removal was still extremely robust, but removal of EDTA and TKN were sensitive to prolonged episodes of low dissolved oxygen. Nitrogen mass balance suggested 30 to 40% TKN removal by assimilation and 60 to 70% by nitrification (including up to 34% TKN removal via subsequent denitrification). Dicyclohexylamine appeared to be readily biodegraded. Maximum DCHA and EDTA degradation rates between pH 7 and 8 were found. An Arthrobacter sp. capable of growth on DCHA as the sole source of carbon and energy was isolated.

Removal of cadmium (II) from simulated wastewater by ion flotation technique

PubMed Central

2013-01-01

A separation technique which has recently received a sharp increase in research activities is “ion flotation”. This technique has four important advantages for treating wastewaters: low energy consumption, small space requirements, small volume of sludge and acting selectively. The present study aims to optimize parameters of ion flotation for cadmium removal in simulated wastewater at laboratory scale. It was obtained on the reaction between Cd2+ and sodium dodecylesulfate (SDS) collector followed by flotation with ethanol as frother. Test solution was prepared by combining the required amount of cadmium ion, SDS and necessary frother or sodium sulfate solution. All experiments were carried out in a flotation column at laboratory temperature (27°C), adjusted pH = 4 and 120 minutes. The different parameters (namely: flow rate, cadmium, SDS and frother concentrations and ionic strength) influencing the flotation process were examined. The best removal efficiency obtained at a collector-metal ratio of 3:1 in 60 min with flow rate of 150 mL/min was 84%. The maximum cadmium removal was 92.1% where ethanol was introduced at a concentration 0.4% to flotation column with above conditions. The obtained results were promising, as both cadmium and collector were effectively removed from wastewater. Hence, the application of ion flotation for metal ions removal from effluents seems to be efficient. PMID:23388386

Study on hot melt pressure sensitive coil material for removing surface nuclear pollution dust

NASA Astrophysics Data System (ADS)

Wang, Jing; Li, Jiao; Wang, Jianhui; Zheng, Li; Li, Jian; Lv, Linmei

2018-02-01

A new method for removing surface nuclear pollution by using hot melt pressure sensitive membrane was presented. The hot melt pressure sensitive membrane was designed and prepared by screening hot melt pressure sensitive adhesive and substrate. The simulated decontamination test of the hot melt pressure sensitive membrane was performed by using 100 mesh and 20 mesh standard sieve dust for simulation of nuclear explosion fall ash and radioactive contaminated particles, respectively. It was found that the single decontamination rate of simulated fall ash and contaminated particles were both above 80% under pressure conditions of 25kPa or more at 140°C. And the maximum single decontamination rate was 92.5%. The influence of heating temperature and pressure on the decontamination rate of the membrane was investigated at the same time. The results showed that higher heating temperature could increase the decontamination rate by increasing the viscosity of the adhesive. When the adhesive amount of the adhesive layer reached saturation, a higher pressure could increase the single decontamination rate also.

RAPID REMOVAL OF A GROUNDWATER CONTAMINANT PLUME.

USGS Publications Warehouse

Lefkoff, L. Jeff; Gorelick, Steven M.; ,

1985-01-01

A groundwater management model is used to design an aquifer restoration system that removes a contaminant plume from a hypothetical aquifer in four years. The design model utilizes groundwater flow simulation and mathematical optimization. Optimal pumping and injection strategies achieve rapid restoration for a minimum total pumping cost. Rapid restoration is accomplished by maintaining specified groundwater velocities around the plume perimeter towards a group of pumping wells located near the plume center. The model does not account for hydrodynamic dispersion. Results show that pumping costs are particularly sensitive to injection capacity. An 8 percent decrease in the maximum allowable injection rate may lead to a 29 percent increase in total pumping costs.

Ex-situ bioremediation of crude oil in soil, a comparative kinetic analysis.

PubMed

Mohajeri, Leila; Aziz, Hamidi Abdul; Isa, Mohamed Hasnain; Zahed, Mohammad Ali; Mohajeri, Soraya

2010-07-01

Weathered crude oil (WCO) removals in shoreline sediment samples were monitored for 60 days in bioremediation experimentation. Experimental modeling was carried out using statistical design of experiments. At optimum conditions maximum of 83.13, 78.06 and 69.92% WCO removals were observed for 2, 16 and 30 g/kg initial oil concentrations, respectively. Significant variations in the crude oil degradation pattern were observed with respect to oil, nutrient and microorganism contents. Crude oil bioremediation were successfully described by a first-order kinetic model. The study indicated that the rate of hydrocarbon biodegradation increased with decrease of crude oil concentrations.

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.

Effects of temperature on the removal efficiency of KDP crystal during the process of magnetorheological water-dissolution polishing.

PubMed

Zhang, Yifan; Dai, Yifan; Tie, Guipeng; Hu, Hao

2016-10-10

As a kind of important nonlinear optical element, KDP crystal has great demand in the inertial confinement fusion system. Based on the dissolution mechanism of solid materials, the factors that affect the material removal rate of KDP crystal in magnetorheological (MR) water-dissolution polishing are investigated to improve the machining efficiency. It is found that the material removal rate is proportional to the product of the saturation concentration and diffusion coefficient, and the relationship between the removal efficiency and the temperature meets the unilateral Gaussian function. Polishing experiments are carried out on a magnetorheological finishing (MRF) machine with self-designed MRF fluid heating devices. The experimental results show that practical efficiency-temperature curve is consistent with the theoretical curve, and the maximum machining efficiency increases by about 50% with the rise of temperature from 294 to 302 K. Meanwhile, when the MR fluid temperature is lower than 308 K, the crystal surface quality and surface roughness in different processing temperatures have no remarkable difference with constant crystal temperature (294 K). This research indicates that it is feasible to drastically improve KDP crystal MRF efficiency by controlling the processing temperature.

Removal of Cr, Mn, and Co from textile wastewater by horizontal rotating tubular bioreactor.

PubMed

Zeiner, Michaela; Rezić, Tonci; Santek, Bozidar; Rezić, Iva; Hann, Stephan; Stingeder, Gerhard

2012-10-02

Environmental pollution by industrial wastewaters polluted with toxic heavy metals is of great concern. Various guidelines regulate the quality of water released from industrial plants and of surface waters. In wastewater treatment, bioreactors with microbial biofilms are widely used. A horizontal rotating tubular bioreactor (HRTB) is a combination of a thin layer and a biodisc reactor with an interior divided by O-ring shaped partition walls as carriers for microbial biomass. Using a biofilm of heavy metal resistant bacteria in combination with this special design provides various advantages for wastewater treatment proven in a pilot study. In the presented study, the applicability of HRTB for removing metals commonly present in textile wastewaters (chromium, manganese, cobalt) was investigated. Artificial wastewaters with a load of 125 mg/L of each metal underwent the bioreactor treatment. Different process parameters (inflow rate, rotation speed) were applied for optimizing the removal efficiency. Samples were drawn along the bioreactor length for monitoring the metal contents on site by UV-vis spectrometry. The metal uptake of the biomass was determined by ICP-MS after acidic microwave assisted digestion. The maximum removal rates obtained for chromium, manganese, and cobalt were: 100%, 94%, and 69%, respectively.

Coal desulfurization by low temperature chlorinolysis, phase 2

NASA Technical Reports Server (NTRS)

Kalvinskas, J. J.; Grohmann, K.; Rohatgi, N.; Ernest, J.; Feller, D.

1980-01-01

An engineering scale reactor system was constructed and operated for the evaluation of five high sulfur bituminous coals obtained from Kentucky, Ohio, and Illinois. Forty-four test runs were conducted under conditions of 100 by 200 mesh coal,solvents - methlychloroform and water, 60 to 130 C, 0 to 60 psig, 45 to 90 minutes, and gaseous chlorine flow rate of up to 24 SCFH. Sulfur removals demonstrated for the five coals were: maximum total sulfur removal of 46 to 89% (4 of 5 coals with methylchloroform) and 0 to 24% with water. In addition, an integrated continuous flow mini-pilot plant was designed and constructed for a nominal coal rate of 2 kilograms/hour which will be operated as part of the follow-on program. Equipment flow sheets and design drawings are included for both the batch and continuous flow mini-pilot plants.

Anaerobic biodegradation of aircraft deicing fluid in UASB reactors.

PubMed

Tham, P T Pham thi; Kennedy, K J Kevin J

2004-05-01

A central composite design was employed to methodically investigate anaerobic treatment of aircraft deicing fluid (ADF) in bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactors. A total of 23 runs at 17 different operating conditions (0.8% 1.6% ADF (6000-12,000mg/L COD), 12-56h HRT, and 18-36gVSS/L) were conducted in continuous mode. The development of four empirical models describing process responses (i.e. COD removal efficiency, biomass-specific acetoclastic activity, methane production rate, and methane production potential) as functions of ADF concentration, hydraulic retention time, and biomass concentration is presented. Model verification indicated that predicted responses (COD removal efficiencies, biomass-specific acetoclastic activity, and methane production rates and potential) were in good agreement with experimental results. Biomass-specific acetoclastic activity was improved two-fold from 0.23gCOD/gVSS/d for inoculum to a maximum of 0.55gCOD/gVSS/d during ADF treatment in UASB reactors. For the design window, COD removal efficiencies were higher than 90%. The predicted methane production potentials were close to theoretical values, and methane production rates increased as the organic loading rate is increased. ADF toxicity effects were evident for 1.6% ADF at medium organic loadings (SOLR above 0.5gCOD/gVSS/d). In contrast, good reactor stability and excellent COD removal efficiencies were achieved at 1.2% ADF for reactor loadings approaching that of highly loaded systems (0.73gCOD/gVSS/d).

Batch and fixed-bed column study for p-nitrophenol, methylene blue, and U(VI) removal by polyvinyl alcohol-graphene oxide macroporous hydrogel bead.

PubMed

Chen, Dan; Zhou, Jun; Wang, Hongyu; Yang, Kai

2018-01-01

There is an increasing need to explore effective and clean approaches for hazardous contamination removal from wastewaters. In this work, a novel bead adsorbent, polyvinyl alcohol-graphene oxide (PVA-GO) macroporous hydrogel bead was prepared as filter media for p-nitrophenol (PNP), dye methylene blue (MB), and heavy metal U(VI) removal from aqueous solution. Batch and fixed-bed column experiments were carried out to evaluate the adsorption capacities of PNP, MB, and U(VI) on this bead. From batch experiments, the maximum adsorption capacities of PNP, MB, and U(VI) reached 347.87, 422.90, and 327.55 mg/g. From the fixed-bed column experiments, the adsorption capacities of PNP, MB, and U(VI) decreased with initial concentration increasing from 100 to 400 mg/L. The adsorption capacities of PNP, MB, and U(VI) decreased with increasing flow rate. Also, the maximum adsorption capacity of PNP decreased as pH increased from 3 to 9, while MB and U(VI) presented opposite tendencies. Furthermore, the bed depth service Time (BDST) model showed good linear relationships for the three ions' adsorption processes in this fixed-bed column, which indicated that the BDST model effectively evaluated and optimized the adsorption process of PVA-GO macroporous hydrogel bead in fixed-bed columns for hazardous contaminant removal from wastewaters.

Testing a biofilter cover design to mitigate dairy effluent pond methane emissions.

PubMed

Pratt, Chris; Deslippe, Julie; Tate, Kevin R

2013-01-02

Biofiltration, whereby CH(4) is oxidized by methanotrophic bacteria, is a potentially effective strategy for mitigating CH(4) emissions from anaerobic dairy effluent lagoons/ponds, which typically produce insufficient biogas for energy recovery. This study reports on the effectiveness of a biofilter cover design at oxidizing CH(4) produced by dairy effluent ponds. Three substrates, a volcanic pumice soil, a garden-waste compost, and a mixture of the two, were tested as media for the biofilters. All substrates were suspended as 5 cm covers overlying simulated dairy effluent ponds. Methane fluxes supplied to the filters were commensurate with emission rates from typical dairy effluent ponds. All substrates oxidized more than 95% of the CH(4) influx (13.9 g CH(4) m(-3) h(-1)) after two months and continued to display high oxidation rates for the remaining one month of the trial. The volcanic soil biofilters exhibited the highest oxidation rates (99% removal). When the influx CH(4) dose was doubled for a month, CH(4) removal rates remained >90% for all substrates (maximum = 98%, for the volcanic soil), suggesting that biofilters have a high capacity to respond to increases in CH(4) loads. Nitrous oxide emissions from the biofilters were negligible (maximum = 19.9 mg N(2)O m(-3) h(-1)) compared with CH(4) oxidation rates, particularly from the volcanic soil that had a much lower microbial-N (75 mg kg(-1)) content than the compost-based filters (>240 mg kg(-1)). The high and sustained CH(4) oxidation rates observed in this laboratory study indicate that a biofilter cover design is a potentially efficient method to mitigate CH(4) emissions from dairy effluent ponds. The design should now be tested under field conditions.

Biodegradation of airborne acetone/styrene mixtures in a bubble column reactor.

PubMed

Vanek, T; Silva, A; Halecky, M; Paca, J; Ruzickova, I; Kozliak, E; Jones, K

2017-07-29

The ability of a bubble column reactor (BCR) to biodegrade a mixture of styrene and acetone vapors was evaluated to determine the factors limiting the process efficiency, with a particular emphasis on the presence of degradation intermediates and oxygen levels. The results obtained under varied loadings and ratios were matched with the dissolved oxygen levels and kinetics of oxygen mass transfer, which was assessed by determination of k L a coefficients. A 1.5-L laboratory-scale BCR was operated under a constant air flow of 1.0 L.min -1 , using a defined mixed microbial population as a biocatalyst. Maximum values of elimination capacities/maximum overall specific degradation rates of 75.5 gC.m -3 .h -1 /0.197 gC.gdw -1 .h -1 , 66.0 gC.m -3 .h -1 /0.059 gC.gdw -1 .h -1 , and 45.8 gC.m -3 .h -1 /0.027 gC.gdw -1 .h -1 were observed for styrene/acetone 2:1, styrene-rich and acetone-rich mixtures, respectively, indicating significant substrate interactions and rate limitation by biological factors. The BCR removed both acetone and styrene near-quantitatively up to a relatively high organic load of 50 g.m -3 .h -1 . From this point, the removal efficiencies declined under increasing loading rates, accompanied by a significant drop in the dissolved oxygen concentration, showing a process transition to oxygen-limited conditions. However, the relatively efficient pollutant removal from air continued, due to significant oxygen mass transfer, up to a threshold loading rate when the accumulation of acetone and degradation intermediates in the aqueous medium became significant. These observations demonstrate that oxygen availability is the limiting factor for efficient pollutant degradation and that accumulation of intermediates may serve as an indicator of oxygen limitation. Microbial (activated sludge) analyses revealed the presence of amoebae and active nematodes that were not affected by variations in operational conditions.

Efficient removal of nitrobenzene and concomitant electricity production by single-chamber microbial fuel cells with activated carbon air-cathode.

PubMed

Zhang, Enren; Wang, Feng; Zhai, Wenjing; Scott, Keith; Wang, Xu; Diao, Guowang

2017-04-01

Single-chamber microbial fuel cells (S-MFCs) with bio-anodes and activated carbon (AC) air-cathodes showed high nitrobenzene (NB) tolerance and NB removal with concomitant electricity production. The maximum power over 25Wm -3 could be obtained when S-MFCs were operated in the NB loading range of 1.2-6.2molm -3 d -1 , and stable electricity production over 13.7Wm -3 could be produced in a NB loading range of 1.2-14.7molm -3 d -1 . The present S-MFCs exhibited high NB removal performance with NB removal efficiency over 97% even when the NB loading rate was increased to 17.2molm -3 d -1 . The potential NB reduced product (i.e. aniline) could also be effectively removed from influents. The findings in this study means that single-chamber MFCs assembled with pre-enriched bio-anodes and AC air-cathodes could be developed as effective bio-electrochemical systems to remove NB from wastewaters and to harvest energy instead of consuming energy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Integrated Cr(VI) removal using constructed wetlands and composting.

PubMed

Sultana, Mar-Yam; Chowdhury, Abu Khayer Md Muktadirul Bari; Michailides, Michail K; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Vayenas, Dimitrios V

2015-01-08

The present work was conducted to study integrated chromium removal from aqueous solutions in horizontal subsurface (HSF) constructed wetlands. Two pilot-scale HSF constructed wetlands (CWs) units were built and operated. One unit was planted with common reeds (Phragmites australis) and one was kept unplanted. Influent concentrations of Cr(VI) ranged from 0.5 to 10mg/L. The effect of temperature and hydraulic residence time (8-0.5 days) on Cr(VI) removal were studied. Temperature was proved to affect Cr(VI) removal in both units. In the planted unit maximum Cr(VI) removal efficiencies of 100% were recorded at HRT's of 1 day with Cr(VI) concentrations of 5, 2.5 and 1mg/L, while a significantly lower removal rate was recorded in the unplanted unit. Harvested reed biomass from the CWs was co-composted with olive mill wastes. The final product had excellent physicochemical characteristics (C/N: 14.1-14.7, germination index (GI): 145-157%, Cr: 8-10mg/kg dry mass), fulfills EU requirements and can be used as a fertilizer in organic farming. Copyright © 2014 Elsevier B.V. All rights reserved.

Fate and effects of nitrogen and phosphorus in shallow vegetated aquatic ecosystems

USGS Publications Warehouse

Fairchild, James F.; Vradenburg, Leigh Ann

2006-01-01

Nitrate concentrations have greatly increased in streams and rivers draining agricultural regions of the Midwestern United States, increasing nitrate transport to the Gulf of Mexico has been implicated in the hypoxic conditions that threaten the productivity of marine fisheries. Increases in nitrate concentrations have been attributed to a combination of factors including agricultural expansion, increased nitrogen application rates, increased tile drainage, and loss of riparian Wetlands, These landscape-level changes have resulted in a decreased natural capacity for nitrogen uptake, removal, and cycling back to the atmosphere. Land managers are increasingly interested in using wetland construction and rehabilitation as a management practice to reduce loss of nitrate from the terrestrial systems. Yet, relatively little is known about the limnological factors involved in nitrate removal by Wetland systems.We conducted a series of studies from 1999-2000 to investigate the functional capacity of shallow, macrophyte-dominated pond wetland systems for uptake, assimilation, and retention of nitrogen (N) and phosphorus (P). We evaluated four factors that were hypothesized to influence nutrient uptake and assimilation: 1) nitrate loading rates; 2) nitrogen to phosphorus (N.P) ratios; 3) frequency of dosing/application; and 4) timing of dose initiation.Nutrient assimilation was rapid; store than 90% of added nutrients were removed from the water column in all treatments. Neither variation in N:P ratios (evaluated range, <13:1 to -114.1), frequency of application (weekly or bi-weekly), nor liming of dose initiation relative to macrophyte development (0%, 15-25%, or 75-90% maximum biomass) had significant effects on nutrient assimilation of wetland community dynamics. Maximum loading of nitrate (60 g N/m2 2.4 g P/m2) applied as six weekly doses stimulated algal communities, but inhibited macrophyte communities.Predicted shifts from a stable state of macrophyte- to phytoplankton-dominance did not occur due to nutrient additions. Macrophytes, phytoplankton, and the sediment surface were all significant factors in the removal of nitrate from the Water column. Overall, these shallow macrophyte-dominated systems provided an efficient means of removing nutrients from the water column. Construction or rehabilitation of shallow, vegetated wetlands may offer promise as land management practices for nutrient removal in agricultural watersheds.

Evaluating photo-degradation of COD and TOC in petroleum refinery wastewater by using TiO2/ZnO photo-catalyst.

PubMed

Aljuboury, Dheeaa Al Deen Atallah; Palaniandy, Puganeshwary; Abdul Aziz, Hamidi Bin; Feroz, Shaik; Abu Amr, Salem S

2016-09-01

The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO 2 /ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO 2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included a reaction time of 170 min, TiO 2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), and pH 6.8 COD and TOC removal rates of 99% and 74%, respectively. The TOC and COD removal rates correspond well with the predicted models. The maximum removal rate for TOC and COD was 99.3% and 76%, respectively at optimum operational conditions of TiO 2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), reaction time (170 min) and pH (6.8). The new treatment process achieved higher degradation efficiencies for TOC and COD and reduced the treatment time comparing with other related processes.

Effect of variations in the nitrogen loading rate and seasonality on the operation of a free water surface constructed wetland for treatment of swine wastewater.

PubMed

Plaza de Los Reyes, Catalina; Vidal, Gladys

2015-01-01

The aim of this study was to evaluate the effects of variations in the nitrogen loading rate (NLR) and seasonality on the operational efficiency of a free-water surface constructed wetland (FWS) and on the processes involved in total nitrogen (TN) removal in treating swine wastewater. The system, which operated for 550 days, consisted of a FWS mesocosm inoculated with Typha angustifolia L., using swine wastewater from a storage lagoon as an influent. After operating with nitrogen loading rates (NLRs) of 2.0 to 30.2 kg TN ha(-1)·d(-1), the FWS reduced total nitrogen (TN) concentration by between 21.6 and 51.0%, achieving maximum removal (48.2 ± 3.0%) when the system operated at a NLR below 15.0 kg TN ha(-1)·d(-1). Moreover, operations over 25.0 kg TN ha(-1)·d(-1) resulted in a 50.6% decrease in the maximum FWS efficiency, which may have been related to increased anoxic conditions (< 0.5 mg O2 L(-1); -169.8 ± 70.3 mV) resulting from the high concentration of organic matter in the system (12.3 ± 10.5 g TCOD L(-1)), which hindered nitrification. Ammonia volatilization is considered the main method to remove TN, with an average value of 14.4 ± 6.5% (3.1-26.2%). Maximum volatilization occurred during the summer (21.5 ± 2.4°C) at an NLR higher than 25 kg TN ha(-1)·d(-1) (26.6%), favored by higher temperatures (17.3-19.7°C), and high NH4(+)-N (>600.0 9 mg NH4(+)-N L(-1)) and pH levels (7.1-7.9). Uptake by plants accounted for 14.9% of the TN removed, with the vegetative peak in summer (height: 105.3 cm; diameter: 2.1 cm) at an NLR of 25.3 ± 0.3 kg TN ha(-1)·d(-1). However, growth decreased to 94.4% at an NLR of over 25.3 ± 0.3 kg TN ha(-1)·d(-1) (>379.9 mg NH4(+)-N L(-1)) in autumn (17.4 ± 2.4°C). This was associated with the period of plant senescence and the effects of ammonium phytotoxicity (379.9-624.2 mg NH4(+)-N L(-1)) and continued to the end of the study with the complete loss of macrophyte species. Finally, 1.5% of the TN removed was incorporated into the sediments where NH4(+)-N is the main form of nitrogen, with an accumulative value of 2.6 g m(-2).

Preparation of nanomaterials for the ultrasound-enhanced removal of Pb2+ ions and malachite green dye: Chemometric optimization and modeling.

PubMed

Dil, Ebrahim Alipanahpour; Ghaedi, Mehrorang; Asfaram, Arash; Hajati, Shaaker; Mehrabi, Fatemeh; Goudarzi, Alireza

2017-01-01

Copper oxide nanoparticle-loaded activated carbon (CuO-NP-AC) was synthesized and characterized using different techniques such as FE-SEM, XRD and FT-IR. It was successfully applied for the ultrasound-assisted simultaneous removal of Pb 2+ ions and malachite green (MG) dye in binary system from aqueous solution. The effect of important parameters was modeled and optimized by artificial neural network (ANN) and response surface methodology (RSM). Maximum simultaneous removal percentages (>99.0%) were found at 25mgL -1 , 20mgL -1 , 0.02g, 5min and 6.0 corresponding to initial Pb 2+ concentration, initial MG concentration, CuO-NP-AC amount, ultrasonication time and pH, respectively. The precision of the equation obtained by RSM was confirmed by the analysis of variance and calculation of correlation coefficient relating the predicted and the experimental values of ultrasound-assisted simultaneous removal of the analytes. A good agreement between experimental and predicted values was observed. A feed-forward neural network with a topology optimized by response surface methodology was successfully applied for the prediction of ultrasound-assisted simultaneous removal of Pb 2+ ions and MG dye in binary system by CuO-NPs-AC. The number of hidden neurons, MSE, R 2 , number of epochs and error histogram were chosen for ANN modeling. Then, Langmuir, Freundlich, Temkin and D-R isothermal models were applied for fitting the experimental data. It was found that the Langmuir model well describes the isotherm data with a maximum adsorption capacity of 98.328 and 87.719mgg -1 for Pb 2+ and MG, respectively. Kinetic studies at optimum condition showed that maximum Pb 2+ and MG adsorption is achieved within 5min of the start of most experiments. The combination of pseudo-second-order rate equation and intraparticle diffusion model was applicable to explain the experimental data of ultrasound-assisted simultaneous removal of Pb 2+ and MG at optimum condition obtained from RSM. Copyright © 2016 Elsevier B.V. All rights reserved.

Characteristics and enzymatic hydrolysis of cellulose-rich fractions from steam exploded and sequentially alkali delignified bamboo (Phyllostachys pubescens).

PubMed

Sun, Shao-Ni; Cao, Xue-Fei; Zhang, Xue-Ming; Xu, Feng; Sun, Run-Cang; Jones, Gwynn Lloyd

2014-07-01

In this study, cellulose-rich fractions from bamboo were prepared with steam explosion pretreatment (SEP) followed by a successive alkaline delignification to improve the enzymatic digestibility for an efficient bioethanol production. The cellulose-rich fractions obtained were characterized by FT-IR, XRD, CP/MAS (13)C NMR, SEM, and BET surface area. It was found that the SEP alone significantly removed partial hemicelluloses, while the synergistic treatment by SEP and alkaline delignification removed most hemicelluloses and lignin. Results from enzymatic hydrolysis showed that SEP alone improved the enzymatic hydrolysis rate by 7.9-33.1%, while the synergistic treatment by SEP and alkaline delignification enhanced the rate by 45.7-63.9%. The synergistic treatment by SEP at 2.0 MPa for 5 min with water impregnation followed by a successive alkaline delignification with 0.5% NaOH and 70% ethanol containing 1.5% NaOH resulted in a maximum enzymatic hydrolysis rate of 70.6%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of recirculation configurations for biological nutrient removal in a membrane bioreactor.

PubMed

Bekir Ersu, Cagatayhan; Ong, Say Kee; Arslankaya, Ertan; Brown, Patrick

2008-03-01

A 12-L lab-scale membrane bioreactor (MBR), consisting of an anaerobic and anoxic compartment followed by an oxic plate-frame membrane compartment, was evaluated for carbonaceous and nutrient removals by varying the recirculation of mixed liquor and permeate. The hydraulic retention times (HRTs) for the anaerobic, anoxic, and oxic compartments were 2, 2, and 8h, respectively. The solids residence time (SRT) for the oxic compartment was 25 days. Five different recirculation configurations were tested by recirculating mixed liquor and/or permeate recirculation equal to the influent flow rate (identified as 100%) into different locations of the anaerobic and anoxic compartments. Of the five configurations, the configuration with 100% mixed liquor recirculation to the anaerobic compartment and 100% permeate recirculation to the anoxic compartment gave the highest percentage removal with an average 92.3+/-0.5% soluble chemical oxygen demand (sCOD), 75.6+/-0.4% total nitrogen (TN), and 62.4+/-1.3% total phosphorus (TP) removal. When the mixed liquor and permeate recirculation rates were varied for the same configuration, the highest TP removal was obtained for 300% mixed liquor recirculation and 100% permeate recirculation (300%/100%) with a TP removal of 88.1+/-1.3% while the highest TN removal (90.3+/-0.3%) was obtained for 200%/300% recirculation. TN and TP concentrations as low as 4.2+/-0.1 and 1.4+/-0.2mg/L respectively were obtained. Mass loading rates were generally low in the range of 0.11-0.22kgCOD/kgMLSS/d due to high biomass concentrations within the oxic reactor (approx. 8000mg/L). The BioWin model was calibrated against one set of the experimental data and was found to predict the experimental data of effluent TN, TP, and NO(3)(-)-N but over-predicted sCOD and NH(3)-N for various recirculation rates. The anoxic heterotrophic yield for the calibrated model was 0.2kg biomass COD/kg COD utilized while the maximum growth rates were found to be 0.45day(-1) for mu(max-autotroph), 3.2day(-1) for mu(max-heterotroph), and 1.5day(-1) for mu(max-PAO).

Anaerobic monodigestion of poultry manure: determination of operational parameters for CSTR.

PubMed

Chamy, R; León, C; Vivanco, E; Poirrier, P; Ramos, C

2012-01-01

In this work the anaerobic monodigestion for the treatment of turkey manure was evaluated, without its codigestion with another substrate. The effect of the organic loading rate (OLR) and the substrate concentration (high total solids (TS) concentration) or product concentration (high volatile fatty acids (VFA) and/or ammonia (NH(3)-N) concentrations) was studied. The results show that for a continuous stirred tank reactor (CSTR) operation, a maximum of 40 g/L of TS and 4.0 g/L of ammonium (NH(4)(+)) was required. In addition, the maximum organic loading rate (OLR) will not exceed 1.5 kg VS/m(3)d. Higher TS and NH(4)(+) concentrations and OLR lead to a reduction on the methane productivity and volatile solids (VS) removal. During the CSTR operation, a high alkalinity concentration (above 10 g/L CaCO(3)) was found; this situation allowed maintaining a constant and appropriate pH (close to 7.8), despite the VFA accumulation. In this sense, the alkalinity ratio (α) is a more appropriate control and monitoring parameter of the reactor operation compared to pH. Additionally, with this parameter a VS removal of 80% with a methane productivity of 0.50 m(3)(CH4)/m(3)(R)d is achieved.

Anaerobic treatment of winery wastewater in fixed bed reactors.

PubMed

Ganesh, Rangaraj; Rajinikanth, Rajagopal; Thanikal, Joseph V; Ramanujam, Ramamoorty Alwar; Torrijos, Michel

2010-06-01

The treatment of winery wastewater in three upflow anaerobic fixed-bed reactors (S9, S30 and S40) with low density floating supports of varying size and specific surface area was investigated. A maximum OLR of 42 g/l day with 80 +/- 0.5% removal efficiency was attained in S9, which had supports with the highest specific surface area. It was found that the efficiency of the reactors increased with decrease in size and increase in specific surface area of the support media. Total biomass accumulation in the reactors was also found to vary as a function of specific surface area and size of the support medium. The Stover-Kincannon kinetic model predicted satisfactorily the performance of the reactors. The maximum removal rate constant (U(max)) was 161.3, 99.0 and 77.5 g/l day and the saturation value constant (K(B)) was 162.0, 99.5 and 78.0 g/l day for S9, S30 and S40, respectively. Due to their higher biomass retention potential, the supports used in this study offer great promise as media in anaerobic fixed bed reactors. Anaerobic fixed-bed reactors with these supports can be applied as high-rate systems for the treatment of large volumes of wastewaters typically containing readily biodegradable organics, such as the winery wastewater.

Biosorption of lead using Bacillus badius AK strain isolated from compost of green waste (water hyacinth).

PubMed

Vishan, Isha; Sivaprakasam, Senthilkumar; Kalamdhad, Ajay

2017-07-01

The bacterial strain Bacillus badius AK isolated from water hyacinth compost was investigated for biosorption characteristics in Pb(II) removal. Batch mode experiments depicted the optimum conditions for biosorption as pH at 4, the temperature of 30°C, 150 rpm of the rotational speed at biomass concentration of 20 mL with 1.7 × 10 16  colony forming unit per milliliter (CFU/mL) value, at 100-150 mg/L concentration of Pb(II). The bacterial biomass was used in its native and non-pretreated state, unlike the dried, freeze-dried or chemically treated biomass. The biosorption followed pseudo-second-order kinetics and isotherm fitted well to the Langmuir model. Maximum Pb(II) biosorption was observed at 1.7 × 10 16  CFU/mL. Influence of Pb(II) on the growth of bacterial biomass was examined by fitting the monod's model. Specific growth rate and maximum specific growth rate of B. badius AK was observed as 0.05 and 2.54 h -1 , respectively; biomass yield coefficient was 11.81. The results indicated that bacterial biomass was efficient, robust and cheaper biosorbent for removal of Pb(II).

Treatment of old landfill leachate with high ammonium content using aerobic granular sludge.

PubMed

Ren, Yanan; Ferraz, Fernanda; Kang, Abbass Jafari; Yuan, Qiuyan

2017-01-01

Aerobic granular sludge has become an attractive alternative to the conventional activated sludge due to its high settling velocity, compact structure, and higher tolerance to toxic substances and adverse conditions. Aerobic granular sludge process has been studied intensively in the treatment of municipal and industrial wastewater. However, information on leachate treatment using aerobic granular sludge is very limited. This study investigated the treatment performance of old landfill leachate with different levels of ammonium using two aerobic sequencing batch reactors (SBR): an activated sludge SBR (ASBR) and a granular sludge SBR (GSBR). Aerobic granules were successfully developed using old leachate with low ammonium concentration (136 mg L -1  NH 4 + -N). The GSBR obtained a stable chemical oxygen demand (COD) removal of 70% after 15 days of operation; while the ASBR required a start-up of at least 30 days and obtained unstable COD removal varying from 38 to 70%. Ammonium concentration was gradually increased in both reactors. Increasing influent ammonium concentration to 225 mg L -1  N, the GSBR removed 73 ± 8% of COD; while COD removal of the ASBR was 59 ± 9%. The GSBR was also more efficient than the ASBR for nitrogen removal. The granular sludge could adapt to the increasing concentrations of ammonium, achieving 95 ± 7% removal efficiency at a maximum influent concentration of 465 mg L -1  N. Ammonium removal of 96 ± 5% was obtained by the ASBR when it was fed with a maximum of 217 mg L -1  NH 4 + -N. However, the ASBR was partially inhibited by free-ammonia and nitrite accumulation rate increased up to 85%. Free-nitrous acid and the low biodegradability of organic carbon were likely the main factors affecting phosphorus removal. The results from this research suggested that aerobic granular sludge have advantage over activated sludge in leachate treatment.

Combining Ferric Salt and Cactus Mucilage for Arsenic Removal from Water.

PubMed

Fox, Dawn I; Stebbins, Daniela M; Alcantar, Norma A

2016-03-01

New methods to remediate arsenic-contaminated water continue to be studied, particularly to fill the need for accessible methods that can significantly impact developing communities. A combination of cactus mucilage and ferric (Fe(III)) salt was investigated as a flocculation-coagulation system to remove arsenic (As) from water. As(V) solutions, ferric nitrate, and mucilage suspensions were mixed and left to stand for various periods of time. Visual and SEM observations confirmed the flocculation action of the mucilage as visible flocs formed and settled to the bottom of the tubes within 3 min. The colloidal suspensions without mucilage were stable for up to 1 week. Sample aliquots were tested for dissolved and total arsenic by ICP-MS and HGAFS. Mucilage treatment improved As removal (over Fe(III)-only treatment); the system removed 75-96% As in 30 min. At neutral pH, removal was dependent on Fe(III) and mucilage concentration and the age of the Fe(III) solution. The process is fast, achieving maximum removal in 30 min, with the majority of As removed in 10-15 min. Standard jar tests with 1000 μg/L As(III) showed that arsenic removal and settling rates were pH-dependent; As removal was between 52% (high pH) and 66% (low pH).

Characteristics of BPA removal from water by PACl-Al13 in coagulation process.

PubMed

Xiaoying, Ma; Guangming, Zeng; Chang, Zhang; Zisong, Wang; Jian, Yu; Jianbing, Li; Guohe, Huang; Hongliang, Liu

2009-09-15

This paper discussed the coagulation characteristics of BPA with polyaluminum chloride (PACl-Al(13)) as coagulant, examined the impact of coagulation pH, PACl-Al(13) dosage, TOC (total organic carbon) and turbidity on BPA removal, and analyzed the possible dominant mechanisms in water coagulation process. Formation and performance of flocs during coagulation processes were monitored using photometric dispersion analyzer (PDA). When the concentration of humic acid matters and turbidity was low in the solution, the experimental results showed that the removal of BPA experienced increase and subsequently decrease with the PACl-Al(13) dosage increasing. The optimal PACl-Al(13) dosage was found at BPA/PACl-Al(13)=1:2.6(M/M) under our experiment conditions. Results show that the maximum BPA removal efficiency occurred at pH 9.0 due to the adsorption by Al(13) aggregates onto BPA rather than charge neutralization mechanism by polynuclear aluminous salts in the solution. The humic acid matters and kaolin in the solution have significant effect on BPA removal with PACl-Al(13) in the coagulation. The BPA removal will be weakened at high humic matters. The removal rate of BPA increased and subsequently decreased with the turbidity increasing.

Biosorption of Azo dyes by spent Rhizopus arrhizus biomass

NASA Astrophysics Data System (ADS)

Salvi, Neeta A.; Chattopadhyay, S.

2017-10-01

In the present study, spent Rhizopus arrhizus biomass was used for the removal of six azo dyes from aqueous solutions. The dye removal capacity of the biomass was evaluated by conducting batch tests as a function of contact time, biomass dosage, pH and initial dye concentrations. The pseudo-second-order kinetic model fitted well with the experimental data with correlation coefficients greater than 0.999, suggesting that chemisorptions might be the rate limiting step. The equilibrium sorption data showed good fit to the Langmuir isotherm model. Among the six dyes tested, the maximum monolayer adsorption capacity for fast red A and metanil yellow was found to be 108.8 and 128.5 mg/g, respectively. These encouraging results suggest that dead Rhizopus arrhizus biomass could be a potential biomaterial for the removal of azo dyes from aqueous dye solution.

Membrane-aerated biofilm reactor for the removal of 1,2-dichloroethane by Pseudomonas sp. strain DCA1.

PubMed

Hage, J C; Van Houten, R T; Tramper, J; Hartmans, S

2004-06-01

A membrane-aerated biofilm reactor (MBR) with a biofilm of Pseudomonas sp. strain DCA1 was studied for the removal of 1,2-dichloroethane (DCA) from water. A hydrophobic membrane was used to create a barrier between the liquid and the gas phase. Inoculation of the MBR with cells of strain DCA1 grown in a continuous culture resulted in the formation of a stable and active DCA-degrading biofilm on the membrane. The maximum removal rate of the MBR was reached at a DCA concentration of approximately 80 micro M. Simulation of the DCA fluxes into the biofilm showed that the MBR performance at lower concentrations was limited by the DCA diffusion rate rather than by kinetic constraints of strain DCA1. Aerobic biodegradation of DCA present in anoxic water could be achieved by supplying oxygen solely from the gas phase to the biofilm grown on the liquid side of the membrane. As a result, direct aeration of the water, which leads to undesired coagulation of iron oxides, could be avoided.

Biohydrogen production and wastewater treatment from organic wastewater by anaerobic fermentation with UASB

NASA Astrophysics Data System (ADS)

Wang, Lu; Li, Yong-feng; Wang, Yi-xuan; Yang, Chuan-ping

2010-11-01

In order to discuss the ability of H2-production and wastewater treatment, an up-flow anaerobic sludge bed (UASB) using a synthesized substrate with brown sugar wastewater was conducted to investigate the hydrogen yield, hydrogen producing rate, fermentation type of biohydrogen production, and the chemical oxygen demand (COD) removal rate, respectively. The results show that when the biomass of inoculants was 22.5 g SSṡL-1 and the influent concentration, hydraulic retention time (HRT) and initial pH were within the ranges of 4000˜6000 mg CODṡL-1, 8 h and 5-5.5, respectively, and the biohydrogen producing reactor could work effectively. The maximum hydrogen production rate is 5.98 Lṡd-1. Simultaneously, the concentration of ethanol and acetic acid is around 80% of the aqueous terminal production in the system, which presents the typical ethanol type fermentation. pH is at the range of 4˜4.5 during the whole performing process, however, the removal rate of COD is just about 20%. Therefore, it's still needs further research to successfully achieve the biohydrogen production and wastewater treatment, simultaneously.

Biodegradation kinetics of 1,4-benzoquinone in batch and continuous systems.

PubMed

Kumar, Pardeep; Nemati, Mehdi; Hill, Gordon A

2011-11-01

Combining chemical and biological treatments is a potentially economic approach to remove high concentration of recalcitrant compounds from wastewaters. In the present study, the biodegradation of 1,4-benzoquinone, an intermediate compound formed during phenol oxidation by chlorine dioxide, was investigated using Pseudomonas putida (ATCC 17484) in batch and continuous bioreactors. Batch experiments were conducted to determine the effects of 1,4-benzoquinone concentration and temperature on the microbial activity and biodegradation kinetics. Using the generated data, the maximum specific growth rate and biodegradation rate were determined as 0.94 h(-1) and 6.71 mg of 1,4-benzoquinone l(-1) h(-1). Biodegradation in a continuous bioreactor indicated a linear relationship between substrate loading and biodegradation rates prior to wash out of the cells, with a maximum biodegradation rate of 246 mg l(-1) h(-1) observed at a loading rate of 275 mg l(-1) h(-1) (residence time: 1.82 h). Biokinetic parameters were also determined using the steady state substrate and biomass concentrations at various dilution rates and compared to those obtained in batch cultures.

Kinetic aspects of chain growth in Fischer-Tropsch synthesis.

PubMed

Filot, Ivo A W; Zijlstra, Bart; Broos, Robin J P; Chen, Wei; Pestman, Robert; Hensen, Emiel J M

2017-04-28

Microkinetics simulations are used to investigate the elementary reaction steps that control chain growth in the Fischer-Tropsch reaction. Chain growth in the FT reaction on stepped Ru surfaces proceeds via coupling of CH and CR surface intermediates. Essential to the growth mechanism are C-H dehydrogenation and C hydrogenation steps, whose kinetic consequences have been examined by formulating two novel kinetic concepts, the degree of chain-growth probability control and the thermodynamic degree of chain-growth probability control. For Ru the CO conversion rate is controlled by the removal of O atoms from the catalytic surface. The temperature of maximum CO conversion rate is higher than the temperature to obtain maximum chain-growth probability. Both maxima are determined by Sabatier behavior, but the steps that control chain-growth probability are different from those that control the overall rate. Below the optimum for obtaining long hydrocarbon chains, the reaction is limited by the high total surface coverage: in the absence of sufficient vacancies the CHCHR → CCHR + H reaction is slowed down. Beyond the optimum in chain-growth probability, CHCR + H → CHCHR and OH + H → H 2 O limit the chain-growth process. The thermodynamic degree of chain-growth probability control emphasizes the critical role of the H and free-site coverage and shows that at high temperature, chain depolymerization contributes to the decreased chain-growth probability. That is to say, during the FT reaction chain growth is much faster than chain depolymerization, which ensures high chain-growth probability. The chain-growth rate is also fast compared to chain-growth termination and the steps that control the overall CO conversion rate, which are O removal steps for Ru.

Arsenic(V) Removal in Wetland Filters Treating Drinking Water with Different Substrates and Plants.

PubMed

Wu, Min; Li, Qingyun; Tang, Xianqiang; Huang, Zhuo; Lin, Li; Scholz, Miklas

2014-05-01

Constructed wetlands are an attractive choice for removing arsenic (As) within water resources used for drinking water production. The role of substrate and vegetation in As removal processes is still poorly understood. In this study, gravel, zeolite (microporous aluminosilicate mineral), ceramsite (lightweight expanded clay aggregate) and manganese sand were tested as prospective substrates while aquatic Juncus effuses (Soft Rush or Common Rush) and terrestrial Pteris vittata L. (Chinese Ladder Brake; known as As hyperaccumulator) were tested as potential wetland plants. Indoor batch adsorption experiments combined with outdoor column experiments were conducted to assess the As removal performances and process mechanisms. Batch adsorption results indicated that manganese sand had the maximum As(V) adsorption rate of 4.55 h -1 and an adsorption capacity of 42.37 μg/g compared to the other three aggregates. The adsorption process followed the pseudo-first-order kinetic model and Freundlich isotherm equations better than other kinetic and isotherm models. Film-diffusion was the rate-limiting step. Mean adsorption energy calculation results indicated that chemical forces, particle diffusion and physical processes dominated As adsorption to manganese sand, zeolite and gravel, respectively. During the whole running period, manganese sand-packed wetland filters were associated with constantly 90% higher As(V) reduction of approximate 500 μg/L influent loads regardless if planted or not. The presence of P. vittata contributed to no more than 13.5% of the total As removal. In contrast, J. effuses was associated with a 24% As removal efficiency.

Utilization of powdered waste sludge (PWS) for removal of textile dyestuffs from wastewater by adsorption.

PubMed

Ozmihci, Serpil; Kargi, Fikret

2006-11-01

Acid pre-treated powdered waste sludge (PWS) was used for removal of textile dyestuffs from aqueous medium by adsorption as an alternative to the use of powdered activated carbon (PAC). The rate and extent of dysetuff removals were determined for four different dyestuffs at different PWS concentrations varying between 1 and 6 gl(-1). Biosorbed dyestuff concentrations at equilibrium decreased with increasing PWS concentration for all dyestuffs tested. PWS was more effective for adsorption of Remazol red RR and Chrisofonia direct yellow 12 as compared to the other dyestuffs tested. More than 80% percent dyestuff removal was obtained for all dyestuffs at PWS concentrations above 4 gl(-1) after 6h of incubation. Similar to percent dyestuff removal, the rate of adsorption was maximum at a PWS concentration of 4 gl(-1). Kinetics of adsorption of dyestuffs was investigated by using the first- and second-order kinetic models and the kinetic constants were determined. Second-order kinetics was found to fit the experimental data better than the first-order model for all dyestuffs tested. Adsorption isotherms were established for all dyestuffs used and the isotherm constants were determined by using the experimental data. Langmuir and the generalized adsorption isotherms were found to be more suitable than the Freundlich isotherm for correlation of equilibrium adsorption data. Acid pre-treated PWS was proven to be an effective adsorbent for dyestuff removal as compared to the other adsorbents reported in literature studies.

Biofiltration of Chloroform in a Trickle Bed Air Biofilter Under ...

EPA Pesticide Factsheets

In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and ethanol. The TBAB is composed of pelleted diatomaceous earth filter media inoculated with filamentous fungi species, which served as the principle biodegrading microorganism. The removal efficiencies of 5 ppmv of chloroform mixed with different ratios of ethanol as cometabolite (25, 50, 100, 150, and 200 ppmv) ranged between 69.9 and 80.9%. The removal efficiency, reaction rate kinetics, and the elimination capacity increased proportionately with an increase in the cometabolite concentration. The carbon recovery from the TBAB amounted to 69.6% of the total carbon input. It is postulated that the remaining carbon contributed to excess biomass yield within the system. Biomass control strategies such as starvation and stagnation were employed at different phases of the experiment. The chloroform removal kinetics provided a maximum reaction rate constant of 0.0018 s−1. The highest ratio of chemical oxygen demand (COD)removal/nitrogenutilization was observed at 14.5. This study provides significant evidence that the biodegradation of a highly chlorinated methane can be favored by cometabolism in a fungi-based TBAB. Chloroform is volatile hazardous chemical emitted from publicly owned treatment

Effects of process operating conditions on the autotrophic denitrification of nitrate-contaminated groundwater using bioelectrochemical systems.

PubMed

Cecconet, D; Devecseri, M; Callegari, A; Capodaglio, A G

2018-02-01

Nitrates have been detected in groundwater worldwide, and their presence can lead to serious groundwater use limitations, especially because of potential health problems. Amongst different options for their removal, bioelectrochemical systems (BESs) have achieved promising results; in particular, attention has raised on BES-driven autotrophic denitrification processes. In this work, the performance of a microbial electrolysis cell (MEC) for groundwater autotrophic denitrification, is assessed in different conditions of nitrate load, hydraulic retention time (HRT) and process configuration. The system obtained almost complete nitrate removal under all conditions, while nitrite accumulation was recorded at nitrate loads higher than 100mgNO 3 - L -1 . The MEC system achieved, in different tests, a maximum nitrate removal rate of 62.15±3.04gNO 3 - -Nm -3 d -1 , while the highest TN removal rate observed was 35.37±1.18gTNm -3 d -1 . Characteristic of this process is a particularly low (in comparison with other reported works) energy consumption: 3.17·10 -3 ±2.26·10 -3 kWh/gNO 3 - N removed and 7.52·10 -2 ±3.58·10 -2 kWhm -3 treated. The anolyte configuration in closed loop allowed the process to use less clean water, while guaranteeing identical performances as in other conventional configurations. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous Heterotrophic Nitrification and Aerobic Denitrification by Chryseobacterium sp. R31 Isolated from Abattoir Wastewater

PubMed Central

Kundu, Pradyut; Pramanik, Arnab; Dasgupta, Arpita; Mukherjee, Somnath; Mukherjee, Joydeep

2014-01-01

A heterotrophic carbon utilizing microbe (R31) capable of simultaneous nitrification and denitrification (SND) was isolated from wastewater of an Indian slaughterhouse. From an initial COD value of 583.0 mg/L, 95.54% was removed whilst, from a starting NH4 +-N concentration of 55.7 mg/L, 95.87% was removed after 48 h contact. The concentrations of the intermediates hydroxylamine, nitrite, and nitrate were low, thus ensuring nitrogen removal. Aerobic denitrification occurring during ammonium removal by R31 was confirmed by utilization of both nitrate and nitrite as nitrogen substrates. Glucose and succinate were superior while acetate and citrate were poor substrates for nitrogen removal. Molecular phylogenetic identification, supported by chemotaxonomic and physiological properties, assigned R31 as a close relative of Chryseobacterium haifense. The NH4 +-N utilization rate and growth of strain R31 were found to be higher at C/N = 10 in comparison to those achieved with C/N ratios of 5 and 20. Monod kinetic coefficients, half saturation concentration (K s), maximum rate of substrate utilization (k), yield coefficient, (Y) and endogenous decay coefficient (K d) indicated potential application of R31 in large-scale SND process. This is the first report on concomitant carbon oxidation, nitrification, and denitrification in the genus Chryseobacterium and the associated kinetic coefficients. PMID:24991552

Continuous anaerobic digestion of food waste and design of digester with lipid removal.

PubMed

Li, Dong; Sun, Yongming; Guo, Yanfeng; Yuan, Zhenhong; Wang, Yao; Zhen, Feng

2013-01-01

Separation of municipal solid waste has been implemented in many cities in China. As a major component of municipal solid waste, food waste can be treated by anaerobic digestion (AD) for energy production. To provide reference data for disposing of food waste through engineering applications, continuous AD was carried out under various organic loading rates (OLRs) at 27 +/- 2 degrees C in the laboratory. The anaerobic reactor was stable with pH 7.0-7.1, total volatile fatty acid (VFA) concentrations of 206-746 mg/L, and NH4+ -N concentrations of 525-1293 mg/L when the OLR was 1.118-5.588 kg volatile solids (VS)/m(3) x d. The maximum volumetric biogas production rate was 4.41 L/L x d when the OLR was increased to 5.588 kg VS/m(3) x d with a hydraulic retention time of 30 d. When the OLR was increased to 6.706 and 8.382 kg VS/m(3) x d, biogas production was seriously inhibited by VFAs, with maximum total VFA and propionate concentrations of 8738 mg/L and 2864 mg/L, respectively. Due to the incomplete degradation of lipids, the specific methane production rate of 353-488 L/kg VS accounted for 55.2-76.3% of the theoretical methane potential calculated based on the component composition. A retrofitted anaerobic digester with lipid removal was designed to improve the efficiency.

Simultaneous removal of potent cyanotoxins from water using magnetophoretic nanoparticle of polypyrrole: adsorption kinetic and isotherm study.

PubMed

Hena, S; Rozi, R; Tabassum, S; Huda, A

2016-08-01

Cyanotoxins, microcystins and cylindrospermopsin, are potent toxins produced by cyanobacteria in potable water supplies. This study investigated the removal of cyanotoxins from aqueous media by magnetophoretic nanoparticle of polypyrrole adsorbent. The adsorption process was pH dependent with maximum adsorption occurring at pH 7 for microcystin-LA, LR, and YR and at pH 9 for microcystin-RR and cylindrospermopsin (CYN). Kinetic studies and adsorption isotherms reflected better fit for pseudo-second-order rate and Langmuir isotherm model, respectively. Thermodynamic calculations showed that the cyanotoxin adsorption process is endothermic and spontaneous in nature. The regenerated adsorbent can be successfully reused without appreciable loss of its original capacity.

Multiple Export Production and Sulfur Isotope Records over the Paleocene Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Gray, E.; Paytan, A.

2007-12-01

The Paleocene Eocene Thermal Maximum (PETM) was a global climatic event that occurred 55 million years ago. δ18O values from benthic foraminifera indicate that temperatures rose 4-5°C coeval with a precipitous drop in δ13C values that indicate a new source of carbon rapidly entered the global carbon cycle. Marine barite (BaSO4) was used to evaluate the 1) barite accumulation rate that serves a proxy for export production and 2) the sulfur isotopic composition of seawater that reflects the mass balance of oceanic sulfate (SO42-). Increased barite accumulation rates at the PETM suggest that increased export production and CO2 sequestration was in direct response to the carbon isotope excursion, although not all of the increases are accounted for. High resolution δ34S values are lower but within reasonable range of previously observed values and indicate a decrease in sulfate removal by pyrite deposition.

High tolerance of and removal of cefazolin sodium in single-chamber microbial fuel cells operation.

PubMed

Zhang, Enren; Yu, Qingling; Zhai, Wenjing; Wang, Feng; Scott, Keith

2018-02-01

Single-chamber microbial fuel cells (MFCs) have been shown to be a promising approach for cefazolin sodium (CFZS)-contaminated wastewater treatment, in terms of electricity production, high CFZS tolerance and effective CFZS removal. MFCs exposed to CFZS loadings up to 100 mg L -1 , produced stable power of 18.2 ± 1.1 W m -3 and a maximum power of 30.4 ± 2.1 W m -3 , similar to that of CFZS-free MFCs (stable power 19.4 ± 0.8 W m -3 and maximum power 32.5 ± 1.6 W m -3 ), notwithstanding a longer acclimitisation MFC activation. More anodophilic genera (i.e. Acinetobacter, Stenotrophomonas, Lysinibacillus) and antibiotic-resisting genera (i.e. Dysgonomonas) were enriched in CFZS acclimitised anodes. Both the thickness of biofilms and the duration of CFZS acclimitisation were essential for the development of high CFZS tolerance (e.g. 450 mg L -1 ). The inhibition of MFCs by CFZS was reversible. The present MFCs generated a CFZS removal rate of 1.2-6.8 mg L -1  h -1 without any apparent inhibition of electricity production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Green synthesis of Fe3O4 nanoparticles loaded sawdust carbon for cadmium (II) removal from water: Regeneration and mechanism.

PubMed

Kataria, Navish; Garg, V K

2018-06-04

This study focused on the synthesis and characterization of novel magnetic iron oxide nanoparticles loaded sawdust carbon (Fe 3 O 4 /SC) and EDTA modified Fe 3 O 4 /SC (EDTA@Fe 3 O 4 /SC) nanocomposites (ncs) by low cost biogenic green synthesis approach and their application for Cd (II) removal from aqueous medium in batch mode. In isotherm studies, Langmuir and Freundlich models are best fitted to Cd (II) removal data. Langmuir maximum adsorption capacity of EDTA@Fe 3 O 4 /SC ncs was found to be 63.3, 22.4 and 25 mg/g that is greater than maximum adsorption capacity of Fe 3 O 4 /SC ncs that is 51, 18.9 and 15 mg/g at the adsorbent doses of 0.4, 1.2 and 2.0 g/L, respectively. Cd (II) adsorption rate is well explained by Pseudo-second order model. Cd (II) adsorption process is spontaneous and endothermic in nature expressed by Enthalpy, Entropy and Free Energy change. The results of regeneration studies showed that EDTA modified Fe 3 O 4 /SC ncs is promising, low cost and eco-friendly for heavy metal adsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

The effects of CO₂ addition along a pH gradient on wastewater microalgal photo-physiology, biomass production and nutrient removal.

PubMed

Sutherland, Donna L; Howard-Williams, Clive; Turnbull, Matthew H; Broady, Paul A; Craggs, Rupert J

2015-03-01

Carbon limitation in domestic wastewater high rate algal ponds is thought to constrain microalgal photo-physiology and productivity, particularly in summer. This paper investigates the effects of CO₂ addition along a pH gradient on the performance of wastewater microalgae in high rate algal mesocosms. Performance was measured in terms of light absorption, electron transport rate, photosynthetic efficiency, biomass production and nutrient removal efficiency. Light absorption by the microalgae increased by up to 128% with increasing CO₂ supply, while a reduction in the package effect meant that there was less internal self-shading thereby increasing the efficiency of light absorption. CO₂ augmentation increased the maximum rate of both electron transport and photosynthesis by up to 256%. This led to increased biomass, with the highest yield occurring at the highest dissolved inorganic carbon/lowest pH combination tested (pH 6.5), with a doubling of chlorophyll-a (Chl-a) biomass while total microalgal biovolume increased by 660% in Micractinium bornhemiense and by 260% in Pediastrum boryanum dominated cultures. Increased microalgal biomass did not off-set the reduction in ammonia volatilisation in the control and overall nutrient removal was lower with CO₂ than without. Microalgal nutrient removal efficiency decreased as pH decreased and may have been related to decreased Chl-a per cell. This experiment demonstrated that CO₂ augmentation increased microalgal biomass in two distinct communities, however, care must be taken when interpreting results from standard biomass measurements with respect to CO₂ augmentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Kinetics and oxidative mechanism for H2O2-enhanced iron-mediated aeration (IMA) treatment of recalcitrant organic compounds in mature landfill leachate.

PubMed

Deng, Yang; Englehardt, James D

2009-09-30

A hydrogen peroxide (H(2)O(2))-enhanced iron (Fe(0))-mediated aeration (IMA) process has been recently demonstrated to effectively remove organic wastes from mature landfill leachate. In this paper, the kinetics and oxidative mechanisms of the enhanced IMA treatment were studied. Bench-scale full factorial tests were conducted in an orbital shaker reactor for treatment of a mature leachate with an initial chemical oxygen demand (COD) of 900-1200 mg/L. At the maximum aeration rate (8.3 mL air/min mL sample), process variables significantly influencing the rates of H(2)O(2) decay and COD removal were pH (3.0-8.0), initial H(2)O(2) doses (0.21-0.84 M), and Fe(0) surface area concentrations (0.06-0.30 m(2)/L). Empirical kinetic models were developed and verified for the degradation of H(2)O(2) and COD. High DO maintained by a high aeration rate slowed the H(2)O(2) self-decomposition, accelerated Fe(0) consumption, and enhanced the COD removal. In hydroxyl radical (OH*) scavenging tests, the rate of removal of glyoxylic acid (target compound) was not inhibited by the addition of para-chlorobenzoic acid (OH* scavenger) at pH 7.0-7.5, ruling out hydroxyl radical as the principal oxidant in neutral-weakly basic solution. These experimental results show that this enhanced IMA technology is a potential alternative for the treatment of high strength recalcitrant organic wastewaters.

Calibration of hydrodynamic behavior and biokinetics for TOC removal modeling in biofilm reactors under different hydraulic conditions.

PubMed

Zeng, Ming; Soric, Audrey; Roche, Nicolas

2013-09-01

In this study, total organic carbon (TOC) biodegradation was simulated by GPS-X software in biofilm reactors with carriers of plastic rings and glass beads under different hydraulic conditions. Hydrodynamic model by retention time distribution and biokinetic measurement by in-situ batch test served as two significant parts of model calibration. Experimental results showed that TOC removal efficiency was stable in both media due to the enough height of column, although the actual hydraulic volume changed during the variation of hydraulic condition. Simulated TOC removal efficiencies were close to experimental ones with low theil inequality coefficient values (below 0.15). Compared with glass beads, more TOC was removed in the filter with plastic rings due to the larger actual hydraulic volume and lower half saturation coefficient in spite of its lower maximum specific growth rate of biofilm, which highlighted the importance of calibrating hydrodynamic behavior and biokinetics. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Survey on the contamination of microcystin-LR in water supply of Shanghai city].

PubMed

Wu, He-yan; Zheng, Li-xing; Su, Jin; Shi, Wei

2005-03-01

To study the pollution level of microcystin-LR in water supply of Shanghai city and the removal efficacy for microcystin-LR through routine water treatment technique. High performance liquid chromatogram (HPLC) was applied to determine the concentration of microcystin-LR in source water, water samples after various water treatment procedures and tap water. The concentration of microcystin-LR varied with sampling seasons and sites and reached peak during summer and fall. The maximum of microcystin-LR was 2.38 microg/L in source water. Coagulation plus chlorine disinfection were found to be effective for the removal of microcystin-LR, while the remove rate through filtration was not significant. And it could also be detected in tap water as high as 1.27 microg/L. The source waters of Shanghai city were polluted by cyanobacteria toxins represented by microcystin-LR. The source water in suburb was more polluted. Routine water treatment techniques can not remove the toxins effectively.

Mixed Wastewater Coupled with CO2 for Microalgae Culturing and Nutrient Removal

PubMed Central

Yao, Lili; Shi, Jianye; Miao, Xiaoling

2015-01-01

Biomass, nutrient removal capacity, lipid productivity and morphological changes of Chlorella sorokiniana and Desmodesmus communis were investigated in mixed wastewaters with different CO2 concentrations. Under optimal condition, which was 1:3 ratio of swine wastewater to second treated municipal wastewater with 5% CO2, the maximum biomass concentrations were 1.22 g L-1 and 0.84 g L-1 for C. sorokiniana and D. communis, respectively. Almost all of the ammonia and phosphorus were removed, the removal rates of total nitrogen were 88.05% for C. sorokiniana and 83.18% for D. communis. Lipid content reached 17.04% for C. sorokiniana and 20.37% for D. communis after 10 days culture. CO2 aeration increased intracellular particle numbers of both microalgae and made D. communis tend to be solitary. The research suggested the aeration of CO2 improve the tolerance of microalgae to high concentration of NH4-N, and nutrient excess stress could induce lipid accumulation of microalgae. PMID:26418261

Developing of a magnetite film of carboxymethyl cellulose grafted carboxymethyl polyvinyl alcohol (CMC-g-CMPVA) for copper removal.

PubMed

Dahlan, Nuraina Anisa; Veeramachineni, Anand Kumar; Langford, Steven James; Pushpamalar, Janarthanan

2017-10-01

Crosslinked carboxymethyl cellulose grafted carboxymethyl polyvinyl alcohol (CMC-g-CMPVA) was loaded with modified magnetite iron oxide (Fe 3 O 4 ) nanoparticles to synthesise a new and easily separable adsorbent for the removal of copper (II) ions from water. The novel adsorbents were characterised by the presence of the functional group, surface morphology, crystallinity and magnetic property. The equilibrium time from the adsorption studies was found to be less than 240min for both film and bead forms while the rate of Cu 2+ removal decreased as the initial Cu 2+ concentration increased. In addition, CMC-g-CMPVA film loaded with Fe 3 O 4 /SiO 2 nanoparticles was the best adsorbent with maximum adsorption capacity of 35.34mg/g and exhibited a reusable potential. The properties exhibited by the new heterogeneous material is a promising adsorbent for the removal and recovery of copper (II) from wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biofiltration of ammonia gas with sponge cubes coated with mixtures of activated carbon and zeolite.

PubMed

Kim, H; Xi, Q; Kim, Y J; Chung, S

2002-08-01

Removal of ammonia gas was investigated using a biofilter system packed with small cubes of polyurethane sponge that were coated with a powder mixture of activated carbon and natural zeolite. Experimental tests and measurements include removal efficiency, pH, metabolic products of ammonia and kinetic analysis. A removal efficiency over 90% can be obtained with ammonia concentrations below 150 ppm and at contact times above 23 sec.The ammonia adsorbing power of the present biocarrier can protect the biofilter system from a high ammonia shock loading in the feed. The maximum removal rate, Vm, obtained from the kinetic analysis is 8.47 g N (kg carrier)(-1) day(-1) and the saturation constant Ks is 50.36 ppm. Nitrite is produced dominantly during the entire experiments. The cell number of nitrifying bacteria is 1.58 x 10( cell (g carrier)(-1). The present synthetic bio-carrier is considered to be one of the best among bio-carriers that have been used for the biofiltration of ammonia.

Preparation of carbon coated Fe3O4 nanoparticles for magnetic separation of uranium

NASA Astrophysics Data System (ADS)

Zhang, Xiaofei; Wang, Jun

2018-01-01

Uranium(VI) was removed from aqueous solutions using carbon coated Fe3O4 nanoparticles (Fe3O4@C). Batch experiments were conducted to study the effects of initial pH, shaking time and temperature on uranium sorption efficiency. It was found that the maximum adsorption capacity of the Fe3O4@C toward uranium(VI) was ∼120.20 mg g-1 when the initial uranium(VI) concentration was 100 mg L-1, displaying a high efficiency for the removal of uranium(VI) ions. Kinetics of the uranium(VI) removal is found to follow pseudo-second-order rate equation. In addition, the uranium(VI)-loaded Fe3O4@C nanoparticles can be recovered easily from aqueous solution by magnetic separation and regenerated by acid treatment. Present study suggested that magnetic Fe3O4@C composite particles can be used as an effective and recyclable adsorbent for the removal of uranium(VI) from aqueous solutions.

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.

Removal of nutrients in denitrification system using coconut coir fibre for the biological treatment of aquaculture wastewater.

PubMed

Manoj, Valsa Remony; Vasudevan, Namasivayam

2012-03-01

Ideal bacterial support medium for fixed film denitrification processes/bioreactors must be inexpensive, durable and possess large surface area with sufficient porosity. The present study has been focussed on removing nitrate nitrogen at two different nitrate nitrogen loading rates (60 (NLR I) and 120 (NLR II) mg l(-1)) from simulated aquaculture wastewater. Coconut coir fibre and a commercially available synthetic reticulated plastic media (Fujino Spirals) were used as packing medium in two independent upflow anaerobic packed bed column reactors. Removal of nitrate nitrogen was studied in correlation with other nutrients (COD, TKN, dissolved orthophosphate). Maximum removal of 97% at NLR-I and 99% at NLR - II of nitrate nitrogen was observed in with either media. Greater consistency in the case of COD removal of upto 81% was observed at NLR II where coconut coir was used as support medium compared to 72% COD removal by Fujino Spirals. The results observed indicate that the organic support medium is just as efficient in nitrate nitrogen removal as conventionally used synthetic support medium. The study is important as it specifically focuses on denitrification of aquaculture wastewater using cheaper organic support medium in anoxic bioreactors for the removal of nitrate nitrogen; which is seldom addressed as a significant problem.

Effect of influent aeration on removal of organic matter from coffee processing wastewater in constructed wetlands.

PubMed

Rossmann, Maike; Matos, Antonio Teixeira; Abreu, Edgar Carneiro; Silva, Fabyano Fonseca; Borges, Alisson Carraro

2013-10-15

The aim of the present study was to evaluate the influence of aeration and vegetation on the removal of organic matter in coffee processing wastewater (CPW) treated in 4 constructed wetlands (CWs), characterized as follows: (i) ryegrass (Lolium multiflorum) cultivated system operating with an aerated influent; (ii) non-cultivated system operating with an aerated influent, (iii) ryegrass cultivated system operating with a non-aerated influent; and (iv) non-cultivated system operating with a non-aerated influent. The lowest average chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of 87, 84 and 73%, respectively, were obtained in the ryegrass cultivated system operating with a non-aerated influent. However, ryegrass cultivation did not influence the removal efficiency of organic matter. Artificial aeration of the CPW, prior to its injection in the CW, did not improve the removal efficiencies of organic matter. On other hand it did contribute to increase the instantaneous rate at which the maximum COD removal efficiency was reached. Although aeration did not result in greater organic matter removal efficiencies, it is important to consider the benefits of aeration on the removal of the other compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-resolution experiments on chemical oxidation of DNAPL in variable-aperture fractures

NASA Astrophysics Data System (ADS)

Arshadi, Masoud; Rajaram, Harihar; Detwiler, Russell L.; Jones, Trevor

2015-04-01

Chemical oxidation of dense nonaqueous-phase liquids (DNAPLs) by permanganate has emerged as an effective remediation strategy in fractured rock. We present high-resolution experimental investigations in transparent analog variable-aperture fractures to improve understanding of chemical oxidation of residual entrapped trichloroethylene (TCE) in fractures. Four experiments were performed with different permanganate concentrations, flow rates, and initial TCE phase geometry. The initial aperture field and evolving entrapped-phase geometry were quantified for each experiment. The integrated mass transfer rate from the TCE phase for all experiments exhibited three time regimes: an early-time regime with slower mass transfer rates limited by low specific interfacial area; an intermediate-time regime with higher mass transfer rates resulting from breakup of large TCE blobs, which greatly increases specific interfacial area; and a late-time regime with low mass transfer rates due to the deposition of MnO2 precipitates. In two experiments, mass balance analyses suggested that TCE mass removal rates exceeded the maximum upper bound mass removal rates derived by assuming that oxidation and dissolution are the only mechanisms for TCE mass removal. We propose incomplete oxidation by permanganate and TCE solubility enhancement by intermediate reaction products as potential mechanisms to explain this behavior. We also speculate that some intermediate reaction products with surfactant-like properties may play a role in lowering the TCE-water interfacial tension, thus causing breakup of large TCE blobs. Our quantitative experimental measurements will be useful in the context of developing accurate computational models for chemical oxidation of TCE in fractures.

[Heavy metals removal and its kinetics in contaminated soil under effects of EDTA washing].

PubMed

Ke, Xin; Li, Pei-Jun; Zhang, Yun; Sun, Tie-Heng

2007-03-01

In this paper, batch experiments were made to examine the effects of different EDTA concentrations, pH, and washing duration of EDTA on the removal of heavy metals from contaminated soil. An empirical model was employed to describe the kinetics of heavy metals dissolution and desorption, and the form changes of test heavy metals were determined before and after EDTA washing. The results showed that EDTA was effective to the removal of heavy-metals from contaminated soil. At 0.1 mol x L(-1) and pH 7 of EDTA and within 24 h, the removal rate of test heavy metals was the maximum, being 89.14% for Cd, 34.78% for Pb, 14.96% for Cu, and 45.14% for Zn. The mass transfer coefficient was in the order of Cd > Zn > Pb > Cu. Sequential fractionations of treated and untreated soil samples showed that EDTA was effective in removing the exchangeable, carbonate and oxide forms of Cd, Pb, Zn and Cu, but ineffective for the organic and residual forms of test heavy metals.

Study on ammonium and organics removal combined with electricity generation in a continuous flow microbial fuel cell.

PubMed

Liu, Shuxin; Li, Lan; Li, Huiqiang; Wang, Hui; Yang, Ping

2017-11-01

A continuous microbial fuel cell system was constructed treating ammonium/organics rich wastewater. Operational performance of MFC system, mechanisms of ammonium removal, effect of ammonium on organics removal and energy output, C and N balance of anode chamber and microbial community analysis of anode chamber were studied. It was concluded that 0.0914kg/m 3 d NH 4 + -N and 5.739kg/m 3 d COD were removed from anode chamber and simultaneous nitrification and denitrification (SND) occurred in cathode chamber resulting in COD, TN removal rate of 88.53%, 71.35% respectively. Excess ammonium affected energy output and the MFC system reached maximum energy output of 816.8mV and 62.94mW/m 3 . In anode chamber, Spirochaetes bacterium sp., Methanobacterium formicicum sp. was predominant in bacteria, archaea communities respectively which contributed to wastewater treatment and electricity generation. This study showed the potential for practical application of continuous flow MFC system treating ammonium/organics rich wastewater and achieving electricity generation simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bifunctional composite from spent "Cyprus coffee" for tetracycline removal and phenol degradation: Solar-Fenton process and artificial neural network.

PubMed

Oladipo, Akeem Adeyemi; Abureesh, Mosab Ali; Gazi, Mustafa

2016-09-01

Removals of tetracycline and photocatalytic degradation of phenol by Fe3O4/coffee residue (MCC) were investigated. Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM) and Boehm titration were employed to characterize MCC. Artificial neural network (ANN) model was developed to predict the tetracycline (TC) concentration in the column effluent. Maximum tetracycline adsorption capacity of 285.6mg/g was observed in a batch system. High removal efficiency (87%) was obtained at 3.3mL/min flow rate, 8.0cm bed height and 50mg/L influent TC concentration in a column system. Complete degradation of phenol by solar-Fenton was attained at 60min irradiation time. Total organic carbon (TOC) removal increased to 63.3% in the presence of 1.0g/L MCC, 1.2g/L H2O2 and solar irradiation. MCC showed remarkable potential to remove antibiotics from wastewater even in the presence of heavy metal (Ni(2+)) via magnetic separation. Copyright © 2015 Elsevier B.V. All rights reserved.

Modeling of the adsorptive removal of arsenic(III) using plant biomass: a bioremedial approach

NASA Astrophysics Data System (ADS)

Roy, Palas; Dey, Uttiya; Chattoraj, Soumya; Mukhopadhyay, Debasis; Mondal, Naba Kumar

2017-06-01

In the present work, the possibility of using a non-conventional finely ground (250 μm) Azadirachta indica (neem) bark powder [AiBP] has been tested as a low-cost biosorbent for the removal of arsenic(III) from water. The removal of As(III) was studied by performing a series of biosorption experiments (batch and column). The biosorption behavior of As(III) for batch and column operations were examined in the concentration ranges of 50-500 µg L-1 and 500.0-2000.0 µg L-1, respectively. Under optimized batch conditions, the AiBP could remove up to 89.96 % of As(III) in water system. The artificial neural network (ANN) model was developed from batch experimental data sets which provided reasonable predictive performance ( R 2 = 0.961; 0.954) of As(III) biosorption. In batch operation, the initial As(III) concentration had the most significant impact on the biosorption process. For column operation, central composite design (CCD) was applied to investigate the influence on the breakthrough time for optimization of As(III) biosorption process and evaluation of interacting effects of different operating variables. The optimized result of CCD revealed that the AiBP was an effective and economically feasible biosorbent with maximum breakthrough time of 653.9 min, when the independent variables were retained at 2.0 g AiBP dose, 2000.0 µg L-1 initial As(III) concentrations, and 3.0 mL min-1 flow rate, at maximum desirability value of 0.969.

The effect of malathion on the activity, performance, and microbial ecology of activated sludge

PubMed Central

Rauglas, Erik; Martin, Seth; Bailey, Kandace; Magnuson, Matthew; Phillips, Rebecca; Harper, Willie F.

2018-01-01

This study evaluated the effect of a VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) surrogate (malathion) on the activity, performance, and ecology of activated sludge bioreactors. In the presence of malathion, the maximum observed respiration rates varied between 43 and 53 μg/O2 min, generally similar to the 49 μg O2/min rates observed in controls. Malathion did not alter the respiration ratio of O2 consumed-to-CO2 produced nor did it impact the shape of the oxygen consumption curves during respirometry. Shorter term (12 h) batch tests showed that both chemical oxygen demand (COD) and ammonia removal were not negatively impacted by the presence of 0.1–3 mg/L malathion. Longer term continuous addition (i.e. 40 days) of 0.1 mg/L of malathion also had no effect on COD and ammonia removal. In contrast to shorter term exposures, longer term continuous addition of 3 mg/L of malathion negatively impacted both COD and nitrogen removal and was associated with shifts in the abundance of species that are common to activated sludge. These results illustrate the impact that chemicals like malathion may have on COD removal, and nitrification, as well as the robustness of activated sludge microbial communities. PMID:27594690

Evolution of titanium residue on the walls of a plasma-etching reactor and its effect on the polysilicon etching rate

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

Hirota, Kosa, E-mail: hirota-kousa@sme.hitachi-hitec.com; Itabashi, Naoshi; Tanaka, Junichi

2014-11-01

The variation in polysilicon plasma etching rates caused by Ti residue on the reactor walls was investigated. The amount of Ti residue was measured using attenuated total reflection Fourier transform infrared spectroscopy with the HgCdTe (MCT) detector installed on the side of the reactor. As the amount of Ti residue increased, the number of fluorine radicals and the polysilicon etching rate increased. However, a maximum limit in the etching rate was observed. A mechanism of rate variation was proposed, whereby F radical consumption on the quartz reactor wall is suppressed by the Ti residue. The authors also investigated a plasma-cleaningmore » method for the removal of Ti residue without using a BCl{sub 3} gas, because the reaction products (e.g., boron oxide) on the reactor walls frequently cause contamination of the product wafers during etching. CH-assisted chlorine cleaning, which is a combination of CHF{sub 3} and Cl{sub 2} plasma treatment, was found to effectively remove Ti residue from the reactor walls. This result shows that CH radicals play an important role in deoxidizing and/or defluorinating Ti residue on the reactor walls.« less

Biodegradation of gas-phase styrene using the fungus Sporothrix variecibatus: impact of pollutant load and transient operation.

PubMed

Rene, Eldon R; Veiga, María C; Kennes, Christian

2010-03-01

Biofiltration of gas-phase styrene was studied using a newly isolated fungus Sporothrix variecibatus, in a perlite biofilter, at inlet concentrations and gas-flow rates ranging from 0.13 to 14 g m(-3) and 0.075 to 0.34 m(3) h(-1), respectively, corresponding to empty bed residence times (EBRT) ranging between 91 and 20s. Styrene loading rates were varied between 50 and 845 g m(-3) h(-1)and a maximum elimination capacity of 336 g m(-3) h(-1) was attained with nearly 65% styrene removal. On the other hand, the critical inlet loads to achieve more than 90% removal were 301, 240 and 92 g m(-3) h(-1) for EBRT of 91, 40, and 20s, respectively. In order to test the stability and shock bearing capacity of the fungal biofilter, short-term tests were conducted by suddenly increasing the gas-phase styrene concentration, while maintaining the gas-flow rate constant. The response, a restoration in the removal performance to previous high values, after subjecting the biofilter to shock loads proves the resilient nature of the attached Sporothrix sp. and its suitability for biofiltration under non-steady state conditions. 2010 Elsevier Ltd. All rights reserved.

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.

Phycoremediation of Heavy Metals in Wet Market Wastewater

NASA Astrophysics Data System (ADS)

Apandi, Najeeha; Saphira Radin Mohamed, Radin Maya; Al-Gheethi, Adel; Latiffi, Atikah; Nor Hidayah Arifin, Siti; Gani, Paran

2018-04-01

The efficiency of phycoremediation using microalgae for removing nutrients and heavy metals from wastewaters has been proved. However, the differences in the composition of wastewaters as well as microalgae species play an important role in the efficient of this process. Therefore, the present study aimed to investigate the effectiveness of Scenedesmus sp. to removal of heavy metals from wet market wastewater. Scenedesmus sp. was inoculated with 106 cells/mL into each wet market wastewater concentration included 10, 25, 50, 75 and 100% and incubated for 18 days. The highest growth rate was recorded in 50% WM with a maximum dry weight of 2006 mg L-1 which subsequently removed 93.06% of Cd, 91.5% of Cr, 92.47% of Fe, 92.40% of Zn. These findings reflected the high potential of Scenedesmus sp. in the treatment of wet market wastewater and production microalgae biomass.

Commercial Coffee Wastes as Materials for Adsorption of Heavy Metals from Aqueous Solutions

PubMed Central

Kyzas, George Z.

2012-01-01

This work aims to study the removal of Cu(II) and Cr(VI) from aqueous solutions with commercial coffee wastes. Materials with no further treatment such as coffee residues from café may act as adsorbents for the removal of Cu(II) and Cr(VI). Equilibrium data were successfully fitted to the Langmuir, Freundlich and Langmuir-Freundlich model (L-F). The maximum adsorption capacity of the coffee residues can reach 70 mg/g for the removal of Cu(II) and 45 mg/g for Cr(VI). The kinetic data were fitted to pseudo-first, -second and -third order equations. The equilibrium was achieved in 120 min. Also, the effect of pH on adsorption and desorption was studied, as well as the influence of agitation rate. Ten cycles of adsorption-desorption were carried out revealing the strong reuse potential of these low-cost adsorbents; the latter was confirmed from a brief economic approach.

Phytoremediation of Heavy Metals in Contaminated Water and Soil Using Miscanthus sp. Goedae-Uksae 1.

PubMed

Bang, Jihye; Kamala-Kannan, Seralathan; Lee, Kui-Jae; Cho, Min; Kim, Chang-Hwan; Kim, Young-Jin; Bae, Jong-Hyang; Kim, Kyong-Ho; Myung, Hyun; Oh, Byung-Taek

2015-01-01

The aim of this study is to characterize the heavy metal phytoremediation potential of Miscanthus sp. Goedae-Uksae 1, a hybrid, perennial, bio-energy crop developed in South Korea. Six different metals (As, Cu, Pb, Ni, Cd, and Zn) were used for the study. The hybrid grass effectively absorbed all the metals from contaminated soil. The maximum removal was observed for As (97.7%), and minimum removal was observed for Zn (42.9%). Similarly, Goedae-Uksae 1 absorbed all the metals from contaminated water except As. Cd, Pb, and Zn were completely (100%) removed from contaminated water samples. Generally, the concentration of metals in roots was several folds higher than in shoots. Initial concentration of metals highly influenced the phytoremediation rate. The results of the bioconcentration factor, translocation factor, and enrichment coefficient tests indicate that Goedae-Uksae 1 could be used for phytoremediation in a marginally contaminated ecosystem.

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.

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.

Effect of production variables on microbiological removal in locally-produced ceramic filters for household water treatment.

PubMed

Lantagne, Daniele; Klarman, Molly; Mayer, Ally; Preston, Kelsey; Napotnik, Julie; Jellison, Kristen

2010-06-01

Diarrhoeal diseases cause an estimated 1.87 million child deaths per year. Point-of-use filtration using locally made ceramic filters improves microbiological quality of stored drinking water and prevents diarrhoeal disease. Scaling-up ceramic filtration is inhibited by lack of universal quality control standards. We investigated filter production variables to determine their affect on microbiological removal during 5-6 weeks of simulated normal use. Decreases in the clay:sawdust ratio and changes in the burnable decreased effectiveness of the filter. Method of silver application and shape of filter did not impact filter effectiveness. A maximum flow rate of 1.7 l(-hr) was established as a potential quality control measure for one particular filter to ensure 99% (2- log(10)) removal of total coliforms. Further research is indicated to determine additional production variables associated with filter effectiveness and develop standardized filter production procedures prior to scaling-up.

Kinetic study on anaerobic oxidation of methane coupled to denitrification.

PubMed

Yu, Hou; Kashima, Hiroyuki; Regan, John M; Hussain, Abid; Elbeshbishy, Elsayed; Lee, Hyung-Sool

2017-09-01

Monod kinetic parameters provide information required for kinetic analysis of anaerobic oxidation of methane coupled to denitrification (AOM-D). This information is critical for engineering AOM-D processes in wastewater treatment facilities. We first experimentally determined Monod kinetic parameters for an AOM-D enriched culture and obtained the following values: maximum specific growth rate (μ max ) 0.121/d, maximum substrate-utilization rate (q max ) 28.8mmol CH 4 /g cells-d, half maximum-rate substrate concentration (K s ) 83μΜ CH 4 , growth yield (Y) 4.76gcells/mol CH 4 , decay coefficient (b) 0.031/d, and threshold substrate concentration (S min ) 28.8μM CH 4 . Clone library analysis of 16S rRNA and mcrA gene fragments suggested that AOM-D reactions might have occurred via the syntrophic interaction between denitrifying bacteria (e.g., Ignavibacterium, Acidovorax, and Pseudomonas spp.) and hydrogenotrophic methanogens (Methanobacterium spp.), supporting reverse methanogenesis-dependent AOM-D in our culture. High μ max and q max , and low K s for the AOM-D enrichment imply that AOM-D could play a significant role in mitigating atmospheric methane efflux. In addition, these high kinetic features suggest that engineered AOM-D systems may provide a sustainable alternative to nitrogen removal in wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Photosynthetic performance of a helical tubular photobioreactor incorporating the cyanobacterium Spirulina platensis

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

Watanabe, Yoshitomo; Hall, D.O.; Nouee, J. De La

1995-07-20

The photosynthetic performance of a helical tubular photobioreactor (``Biocoil``), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape with a 0.25-m{sup 2} basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6-cm inner diameter. The inner surface of the cylinder was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation into the photobioreactor was 2,920 kJ per day. An air-lift system incorporating 4% CO{sub 2} was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 gmore » dry biomass per day which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO{sub 2} was efficiently removed from the gaseous stream; monitoring the CO{sub 2} in the outlet and inlet gas streams showed a 70% removal of CO{sub 2} from the inlet gas over an 8-h period with almost maximum growth rate.« less

Optimizing the performance of microbial fuel cells fed a combination of different synthetic organic fractions in municipal solid waste.

PubMed

Pendyala, Brahmaiah; Chaganti, Subba Rao; Lalman, Jerald A; Heath, Daniel D

2016-03-01

The objective of this study was to establish the impact of different steam exploded organic fractions in municipal solid waste (MSW) on electricity production using microbial fuel cells (MFCs). In particular, the influence of individual steam exploded liquefied waste components (food waste (FW), paper-cardboard waste (PCW) and garden waste (GW)) and their blends on chemical oxygen demand (COD) removal, columbic efficiency (CE) and microbial diversity was examined using a mixture design. Maximum power densities from 0.56 to 0.83 W m(-2) were observed for MFCs fed with different feedstocks. The maximum COD removed and minimum CE were observed for a GW feed. However, a reverse trend (minimum COD removed and maximum CE) was observed for the FW feed. A maximum COD removal (78%) accompanied with a maximum CE (24%) was observed for a combined feed of FW, PCW plus GW in a 1:1:1 ratio. Lactate, the major byproduct detected, was unutilized by the anodic biofilm community. The organic fraction of municipal solid waste (OFMSW) could serve as a potential feedstock for electricity generation in MFCs; however, elevated protein levels will lead to reduced COD removal. The microbial communities in cultures fed FW and PCW was highly diversified; however, the communities in cultures fed FW or a feed mixture containing high FW levels were similar and dominated by Bacteroidetes and β-proteobacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Electricity generation using high concentration terephthalic acid solution by microbial fuel cell].

PubMed

Ye, Ye-Jie; Song, Tian-Shun; Xu, Yuan; Chen, Ying-Wen; Zhu, She-Min; Shen, Shu-Bao

2009-04-15

The high concentration terephthalic acid (TA) solution as the substrate of microbial fuel cell (MFC) was studied to generate electricity. The open circuit voltage was 0.54 V after inoculating for 210 h with anaerobic activated sludge, which proved that TA can be the substrate of microbial fuel cell to generate electricity. The influence of pH and substrate concentration on generating electricity was studied deeply. The voltage output of external resistance (R = 1,000 Omega) was the highest when pH was 8.0. It increased as the substrate concentration increasing and tended towards a maximum value. The maximum voltage output Umax was 0.5 V and Ks was 785.2 mg/L by Monod equation regression. When the substrate concentration (according to COD) was 4000 mg/L, the maximum power density was 96.3 mW/m2, coulomb efficiency was 2.66% and COD removal rate was 80.3%.

Electricity generation from food wastes and microbial community structure in microbial fuel cells.

PubMed

Jia, Jianna; Tang, Yu; Liu, Bingfeng; Wu, Di; Ren, Nanqi; Xing, Defeng

2013-09-01

Microbial fuel cell (MFC) was studied as an alternate and a novel way to dispose food wastes (FWs) in a waste-to-energy form. Different organic loading rate obviously affected the performance of MFCs fed with FWs. The maximum power density of ~18 W/m(3) (~556 mW/m(2)) was obtained at COD of 3200±400 mg/L and the maximum coulombic efficiency (CE) was ~27.0% at COD of 4900±350 mg/L. The maximum removals of COD, total carbohydrate (TC) and total nitrogen (TN) were ~86.4%, ~95.9% and ~16.1%, respectively. Microbial community analysis using 454 pyrosequencing of 16S rRNA gene demonstrated the combination of the dominant genera of the exoelectrogenic Geobacter and fermentative Bacteroides effectively drove highly efficient and reliable MFC systems with functions of organic matters degradation and electricity generation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thermal limits on MV x-ray production by bremsstrahlung targets in the context of novel linear accelerators.

PubMed

Wang, Jinghui; Trovati, Stefania; Borchard, Philipp M; Loo, Billy W; Maxim, Peter G; Fahrig, Rebecca

2017-12-01

To study the impact of target geometrical and linac operational parameters, such as target material and thickness, electron beam size, repetition rate, and mean current on the ability of the radiotherapy treatment head to deliver high-dose-rate x-ray irradiation in the context of novel linear accelerators capable of higher repetition rates/duty cycle than conventional clinical linacs. The depth dose in a water phantom without a flattening filter and heat deposition in an x-ray target by 10 MeV pulsed electron beams were calculated using the Monte-Carlo code MCNPX, and the transient temperature behavior of the target was simulated by ANSYS. Several parameters that affect both the dose distribution and temperature behavior were investigated. The target was tungsten with a thickness ranging from 0 to 3 mm and a copper heat remover layer. An electron beam with full width at half maximum (FWHM) between 0 and3 mm and mean current of 0.05-2 mA was used as the primary beam at repetition rates of 100, 200, 400, and 800 Hz. For a 10 MeV electron beam with FWHM of 1 mm, pulse length of 5 μs, by using a thin tungsten target with thickness of 0.2 mm instead of 1 mm, and by employing a high repetition rate of 800 Hz instead of 100 Hz, the maximum dose rate delivered can increase two times from 0.57 to 1.16 Gy/s. In this simple model, the limiting factor on dose rate is the copper heat remover's softening temperature, which was considered to be 500°C in our study. A high dose rate can be obtained by employing thin targets together with high repetition rate electron beams enabled by novel linac designs, whereas the benefit of thin targets is marginal at conventional repetition rates. Next generation linacs used to increase dose rate need different target designs compared to conventional linacs. © 2017 American Association of Physicists in Medicine.

Complete and simultaneous removal of ammonium and m-cresol in a nitrifying sequencing batch reactor.

PubMed

Zepeda, Alejandro; Ben-Youssef, Chérif; Rincón, Susana; Cuervo-López, Flor; Gómez, Jorge

2013-06-01

The kinetic behavior, oxidizing ability and tolerance to m-cresol of a nitrifying sludge exposed to different initial concentrations of m-cresol (0-150 mg C L(-1)) were evaluated in a sequencing batch reactor fed with 50 mg NH4 (+)-N L(-1) and operated during 4 months. Complete removal of ammonium and m-cresol was achieved independently of the initial concentration of aromatic compound in all the assays. Up to 25 mg m-cresol-C L(-1) (C/N ratio of 0.5), the nitrifying yield (Y-NO3 (-)) was 0.86 ± 0.05, indicating that the nitrate was the main product of the process; no biomass growth was detected. From 50 to 150 mg m-cresol-C L(-1) (1.0 ≤ C/N ≤ 3.0), simultaneous microbial growth and partial ammonium-to-nitrate conversion were obtained, reaching a maximum microbial total protein concentration of 0.763 g L(-1) (247 % of its initial value) and the lowest Y-NO3 (-) 0.53 ± 0.01 at 150 mg m-cresol-C L(-1). m-Cresol induced a significant decrease in the values of both specific rates of ammonium and nitrite oxidation, being the ammonium oxidation pathway the mainly inhibited. The nitrifying sludge was able to completely oxidize up to 150 mg m-cresol-C L(-1) by SBR cycle, reaching a maximum specific removal rate of 6.45 g m-cresol g(-1) microbial protein-N h(-1). The number of SBR cycles allowed a metabolic adaptation of the nitrifying consortium since nitrification inhibition decreased and faster oxidation of m-cresol took place throughout the cycles.

Cutting efficiency of a mid-infrared laser on human enamel.

PubMed

Levy, G; Koubi, G F; Miserendino, L J

1998-02-01

In this study, the cutting ability of a newly developed dental laser was compared with a dental high-speed handpiece and rotary bur for removal of enamel. Measurements of the volume of tissue removed, energy emitted, and time of exposure were used to quantify the ablation rate (rate of tissue removal) for each test group and compared. Cutting efficiency (mm3/s) of the laser was calculated based on the mean volume of tissue removed per pulse (mm3/pulse) and unit energy expended (mm3/J) over the range of applied powers (2, 4, 6, and 8 W). The specimens were then examined by light microscopy and scanning electron micrographs for qualitative analysis of the amount of remaining debris and the presence of the smear layer on the prepared enamel surface. Calculations of the cutting efficiency of the laser over the range of powers tested revealed a linear relationship with the level of applied power. The maximum average rate of tissue removal by the laser was 0.256 mm3/s at 8 W, compared with 0.945 mm3/s by the dental handpiece. Light microscopy and scanning electron micrograph examinations revealed a reduction in the amount of remaining debris and smear layer in the laser-prepared enamel surfaces, compared with the conventional method. Based on the results of this study, the cutting efficiency of the high-speed handpiece and dental bur was 3.7 times greater than the laser over the range of powers tested, but the laser appeared to create a cleaner enamel surface with minimal thermal damage. Further modifications of the laser system are suggested for improvement of laser cutting efficiency.

Arsenic(V) Removal in Wetland Filters Treating Drinking Water with Different Substrates and Plants

PubMed Central

Li, Qingyun; Tang, Xianqiang; Huang, Zhuo; Lin, Li; Scholz, Miklas

2014-01-01

Constructed wetlands are an attractive choice for removing arsenic (As) within water resources used for drinking water production. The role of substrate and vegetation in As removal processes is still poorly understood. In this study, gravel, zeolite (microporous aluminosilicate mineral), ceramsite (lightweight expanded clay aggregate) and manganese sand were tested as prospective substrates while aquatic Juncus effuses (Soft Rush or Common Rush) and terrestrial Pteris vittata L. (Chinese Ladder Brake; known as As hyperaccumulator) were tested as potential wetland plants. Indoor batch adsorption experiments combined with outdoor column experiments were conducted to assess the As removal performances and process mechanisms. Batch adsorption results indicated that manganese sand had the maximum As(V) adsorption rate of 4.55 h–1 and an adsorption capacity of 42.37 μg/g compared to the other three aggregates. The adsorption process followed the pseudo-first-order kinetic model and Freundlich isotherm equations better than other kinetic and isotherm models. Film-diffusion was the rate-limiting step. Mean adsorption energy calculation results indicated that chemical forces, particle diffusion and physical processes dominated As adsorption to manganese sand, zeolite and gravel, respectively. During the whole running period, manganese sand-packed wetland filters were associated with constantly 90% higher As(V) reduction of approximate 500 μg/L influent loads regardless if planted or not. The presence of P. vittata contributed to no more than 13.5% of the total As removal. In contrast, J. effuses was associated with a 24% As removal efficiency. PMID:24771958

Performance Study of Chromium (VI) Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

PubMed Central

Chakraborty, Bhaswati; Indra, Suvendu; Hazra, Ditipriya; Betai, Rupal; Ray, Lalitagauri; Basu, Srabanti

2013-01-01

Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7. PMID:24073400

Depth investigation of rapid sand filters for drinking water production reveals strong stratification in nitrification biokinetic behavior.

PubMed

Tatari, K; Smets, B F; Albrechtsen, H-J

2016-09-15

The biokinetic behavior of NH4(+) removal was investigated at different depths of a rapid sand filter treating groundwater for drinking water preparation. Filter materials from the top, middle and bottom layers of a full-scale filter were exposed to various controlled NH4(+) loadings in a continuous-flow lab-scale assay. NH4(+) removal capacity, estimated from short term loading up-shifts, was at least 10 times higher in the top than in the middle and bottom filter layers, consistent with the stratification of Ammonium Oxidizing Bacteria (AOB). AOB density increased consistently with the NH4(+) removal rate, indicating their primarily role in nitrification under the imposed experimental conditions. The maximum AOB cell specific NH4(+) removal rate observed at the bottom was at least 3 times lower compared to the top and middle layers. Additionally, a significant up-shift capacity (4.6 and 3.5 times) was displayed from the top and middle layers, but not from the bottom layer at increased loading conditions. Hence, AOB with different physiological responses were active at the different depths. The biokinetic analysis predicted that despite the low NH4(+) removal capacity at the bottom layer, the entire filter is able to cope with a 4-fold instantaneous loading increase without compromising the effluent NH4(+). Ultimately, this filter up-shift capacity was limited by the density of AOB and their biokinetic behavior, both of which were strongly stratified. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrologic and climatic changes in three small watersheds after timber harvest.

Treesearch

W.B. Fowler; J.D. Helvey; E.N. Felix

1987-01-01

No significant increases in annual water yield were shown for three small watersheds in northeastern Oregon after shelterwood cutting (30-percent canopy removal, 50-percent basal area removal) and clearcutting. Average maximum air temperature increased after harvest and average minimum air temperature decreased by up to 2.6 °C. Both maximum and minimum water...

Pilot-scale anaerobic co-digestion of municipal biomass waste and waste activated sludge in China: Effect of organic loading rate

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

Liu Xiao, E-mail: liuxiao07@mails.tsinghua.edu.cn; Wang Wei; Shi Yunchun

2012-11-15

Highlights: Black-Right-Pointing-Pointer Co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) was examined on a pilot-scale reactor. Black-Right-Pointing-Pointer System performance and stability under OLR of 1.2, 2.4, 3.6, 4.8, 6.0 and 8.0 kg VS (m{sup 3} d){sup -1} were analyzed. Black-Right-Pointing-Pointer A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and HRT of 15d. Black-Right-Pointing-Pointer With the increasing OLRs, pH values, VS removal rate and methane concentration decreased and VFA increased. Black-Right-Pointing-Pointer The changing of biogas production rate can be a practicalmore » approach to monitor and control anaerobic digestion system. - Abstract: The effects of organic loading rate on the performance and stability of anaerobic co-digestion of municipal biomass waste (MBW) and waste activated sludge (WAS) were investigated on a pilot-scale reactor. The results showed that stable operation was achieved with organic loading rates (OLR) of 1.2-8.0 kg volatile solid (VS) (m{sup 3} d){sup -1}, with VS reduction rates of 61.7-69.9%, and volumetric biogas production of 0.89-5.28 m{sup 3} (m{sup 3} d){sup -1}. A maximum methane production rate of 2.94 m{sup 3} (m{sup 3} d){sup -1} was achieved at OLR of 8.0 kg VS (m{sup 3} d){sup -1} and hydraulic retention time of 15 days. With increasing OLRs, the anaerobic reactor showed a decrease in VS removal rate, average pH value and methane concentration, and a increase of volatile fatty acid concentration. By monitoring the biogas production rate (BPR), the anaerobic digestion system has a higher acidification risk under an OLR of 8.0 kg VS (m{sup 3} d){sup -1}. This result remarks the possibility of relating bioreactor performance with BPR in order to better understand and monitor anaerobic digestion process.« less

Macro-kinetic investigation on phenol uptake from air by biofiltration: Influence of superficial gas flow rate and inlet pollutant concentration

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

Zilli, M.; Fabiano, B.; Ferraiolo, A.

1996-02-20

The macro-kinetic behavior of phenol removal from a synthetic exhaust gas was investigated theoretically as well as experimentally by means of two identical continuously operating laboratory-scale biological filter bed columns. A mixture of peat and glass beads was used as filter material. After sterilization it was inoculated with a pure strain of Pseudomonas putida, as employed in previous experimental studies. To determine the influence of the superficial gas flow rate on biofilter performance and to evaluate the phenol concentration profiles along the column, two series of continuous tests were carried out varying either the inlet phenol concentration, up to 1,650more » mg {center_dot} m{sup {minus}3}, or the superficial gas flow rate, from 30 to 460 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}. The elimination capacity of the biofilter is proved by a maximum volumetric phenol removal rate of 0.73 kg {center_dot} m{sup {minus}3} {center_dot} h{sup {minus}1}. The experimental results are consistent with a biofilm model incorporating first-order substrate elimination kinetics. The model may be considered a useful tool in scaling-up a biofiltration system. Furthermore, the deodorization capacity of the biofilter was investigated, at inlet phenol concentrations up to 280 mg {center_dot} m{sup {minus}3} and superficial gas flow rates ranging from 30 to 92 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}. The deodorization of the gas was achieved at a maximum inlet phenol concentration of about 255 mg {center_dot} m{sup {minus}3}, operating at a superficial gas flow rate of 30 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}.« less

Monitoring Global Sea Level: Eustatic Variations, Local Variations, and Solid Earth Effects

NASA Technical Reports Server (NTRS)

Davis, James L.

2000-01-01

Project BIFROST (Baseline Inferences for Fennoscandian Rebound Observations. Sea-level and Tectonics) combines networks of continuously operating CPS receivers in Sweden and Finland to measure ongoing crustal deformation due to glacial isostatic adjustment, (CIA). We present an analysis of data collected in the years 1993-1998. We compare the CPS determinations of three-dimensional crustal motion to predictions calculated using the high resolution Fennoscandian deglaciation model recently proposed by Lambeck et al. We find that the the maximum observed uplift rate (approx. 10 mm/ yr) and the maximum predicted uplift rate agree to better than 1 mm/ yr. The patterns of uplift also agree quite well, although differences are discernible. The chi(exp 2) difference between predicted and GPS-observed radial rates is reduced by a factor of 5-6 compared to that for the "null" (no uplift) model, depending on whether a mean difference is first removed. The north components of velocity agree at about the same relative level. whereas the agreement for the east components is worse, a problem possibly related to the lack of bias fixing. We have also compared the values for the observed radial deformation rates to those based on sea-level rates from Baltic tide gauges. The weighted RMS difference between CPS and tide-gauge rates (after removing a mean) is 0.6 mm/ yr, giving an indication of the combined accuracy of the CPS and tide-gauge measurement systems. Spectral analysis of the time series of position estimates yields spectral indices in the range -1 to -2. An EOF analysis indicates, however, that much of this power is correlated among the sites. The correlation appears to be regional and falls off only slightly with distance. Some of this correlated noise is associated with snow accumulation on the antennas or, for those antennas with radomes, on the radomes. This problem has caused us to modify the radomes used several times, leading to one of our more significant sources of uncertainty.

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.

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.

Removal of cadmium from contaminated Lentinula edodes by optimized complexation and coagulation.

PubMed

Wang, Yi; Wang, Chen; Cheng, Wei; Bian, Yinbing; Guo, Peng

2017-03-01

Heavy metal pollution is a serious problem for Lentinula edodes ; however, the treatment of contaminated L. edodes has seldom been studied. This study investigated the removal of cadmium (Cd) from contaminated L. edodes and its lentinan by complexation and coagulation. Some influencing factors, such as pH, medical dosage, and preoxidation were examined. Cd complexation from contaminated L .  edodes was shown to be more efficient under acidic conditions (pH 5.0), with a clearance rate of 80.47% in 25 mmol/L EDTA and 78.45% in 25 mmol/L sodium citrate. The Cd content in the lentinan of the contaminated L. edodes was markedly lower than that in the powdered mushroom (2.77 mg/kg vs. 19.49 mg/kg) and was easier to remove. The maximum Cd clearance rate (96.3%) for lentinan was obtained using an optimized process that involved preoxidation with 0.5 mg/L KMnO 4 , complexing with 25 mmol/L EDTA and 25 mmol/L sodium citrate, and coagulation with 50 mg/L activated carbon (AC) at pH 10.0.

[Low field intra-operative magnetic resonance imaging for brain tumour surgery: preliminary experience].

PubMed

Roldán, Pedro; García, Sergio; González, Josep; Reyes, Luis Alberto; Torales, Jorge; Valero, Ricard; Oleaga, Laura; Enseñat, Joaquim

Intra-operative magnetic resonance imaging (iMRI) is a recently introduced tool in the most advanced neurosurgical operating rooms worldwide. We present our preliminary experience in brain tumour surgery with low field PoleStar N30® intraoperative MRI since its introduction in 2013 in the Barcelona Clinic Hospital. A prospective non-randomised study was conducted on cases operated on using iMRI and intention of complete removal up to October 2015. A record was made of the data as regards surgical times, resection rates, histological diagnosis, hospital stay, and survival rates during follow-up. The study included 50 patients, with a mean age of 55 years (±13.7), a preoperative mean Karnofsky of 92 (being 81 post-operatively), and a mean follow-up of 10.5 months (±6.5). There were 26% re-operations due to recurrence. High-grade gliomas were reported in 56%, low-grade gliomas in 24%, and 20% "Other" tumours. Overall hospital stay was 10 days (±4.5). Depending on the histologiacl diagnosis, the "Others" group had a longer hospital stay. Overall, there were 52% complete removal, 18% of maximum removals, and 30% of partial removals. The overall survival rates during follow-up was 84%. iMRI is a safe and effective tool for brain tumour surgery. Its use allows an increase in resection rates, and minimises post-operative complications. Its implementation involves an increase in surgical time, which improves with the characteristic learning curve. More studies are needed to establish its role in the long-term survival of patients. Copyright © 2016 Sociedad Española de Neurocirugía. Publicado por Elsevier España, S.L.U. All rights reserved.

Acetate injection into anaerobic settled sludge for biological P-removal in an intermittently aerated reactor.

PubMed

Ahn, K H; Yoo, H; Lee, J W; Maeng, S K; Park, K Y; Song, K G

2001-01-01

Injecting acetate into the sludge layer during the settling and decanting periods was adopted to enhance phosphorus release inside the sludge layer during those periods and phosphorus uptake during the subsequent aeration period in a KIST Intermittently Decanted Extended Aeration (KIDEA) process. The relationship among nitrification, denitrification and phosphorus removal was investigated in detail and analyzed with a qualitative floc model. Dependencies of nitrification on the maximum DO level during the aerobic phase and phosphorus release on residual nitrate concentration during the settling phase were significant. High degree of nitrification resulted that phosphorus release inside the sludge layer was significantly interfered with nitrate due to the limitation of available acetate and the carbon sources from influent. Such limitation was related to the primary utilization of organic substance for denitrification in the outer layer of the floc and the retarded mass transfer into the inner layer of the floc. Nevertheless, effects of acetate injection on both denitrification and phosphorus release during the settling phase were significant. Denitrification rate after acetate injection was two times as high as that before acetate injection, and phosphorus release reached about 14 mg PO4(3-)-P/g MLVSS/hr during the decanting phase after the termination of denitrification inside the sludge layer. Extremely low level of maximum DO (around 0.5 mg/L) during the aerobic phase may inhibited nitrification, considerably, and thus nearly no nitrate was present. However, the absence of nitrate increased when the phosphorus release rate was reached up to 33 mg PO4(3-)-P/g MLVSS/hr during the settling and decanting phase, and nearly all phosphorus was taken up during subsequent aerobic phase. Since the sludge layer could function as a blocking layer, phosphorus concentrations in the supernatant was not influenced by the released phosphorus inside the sludge layer during the settling and decanting period. Phosphorus removal was directly (for uptake) and indirectly (for release) dependent on the median and maximum DO concentration during the aerobic phase, and those optimal values may exist within the range from 0.2 to 0.6 mg/L and 0.4 to 1.2 mg/L, respectively.

Horizontally rotating disc recirculated photoreactor with TiO2-P25 nanoparticles immobilized onto a HDPE plate for photocatalytic removal of p-nitrophenol.

PubMed

Behnajady, Mohammad A; Dadkhah, Hojjat; Eskandarloo, Hamed

2018-04-01

In this study, a horizontally rotating disc recirculated (HRDR) photoreactor equipped with two UV lamps (6 W) was designed and fabricated for photocatalytic removal of p-nitrophenol (PNP). Photocatalyst (TiO 2 ) nanoparticles were immobilized onto a high-density polyethylene (HDPE) disc, and PNP containing solution was allowed to flow (flow rate of 310 mL min -1 ) in radial direction along the surface of the rotating disc illuminated with UV light. The efficiency of direct photolysis and photocatalysis and the effect of rotating speed on the removal of PNP were studied in the HRDR photoreactor. It was found that TiO 2 -P25 nanoparticles are needed for the effective removal of PNP and there was an optimum rotating speed (450 rpm) for the efficient performance of the HRDR photoreactor. Then effects of operational variables on the removal efficiency were optimized using response surface methodology. The results showed that the predicted values of removal efficiency are consistent with experimental results with an R 2 of 0.9656. Optimization results showed that maximum removal percent (82.6%) was achieved in the HRDR photoreactor at the optimum operational conditions. Finally, the reusability of the HRDR photoreactor was evaluated and the results showed high reusability and stability without any significant decrease in the photocatalytic removal efficiency.

Liquid Phase adsorption kinetics and equilibrium of toluene by novel modified-diatomite.

PubMed

Sheshdeh, Reza Khalighi; Abbasizadeh, Saeed; Nikou, Mohammad Reza Khosravi; Badii, Khashayar; Sharafi, Mohammad Sadegh

2014-01-01

The adsorption equilibria of toluene from aqueous solutions on natural and modified diatomite were examined at different operation parameters such as pH, contact time, initial toluene concentration was evaluated and optimum experimental conditions were identified. The surface area and morphology of the nanoparticles were characterized by SEM, BET, XRD, FTIR and EDX analysis. It was found that in order to obtain the highest possible removal of toluene, the experiments can be carried out at pH 6, temperature 25°C, an agitation speed of 200 rpm, an initial toluene concentration of 150 mg/L, a centrifugal rate of 4000 rpm, adsorbent dosage = 0.1 g and a process time of 90 min. The results of this work show that the maximum percentage removal of toluene from aqueous solution in the optimum conditions for NONMD was 96.91% (145.36 mg/g). Furthermore, under same conditions, the maximum adsorption of natural diatomite was 71.45% (107.18 mg/g). Both adsorption kinetic and isotherm experiments were carried out. The experimental data showed that the adsorption follows the Langmuir model and Freundlich model on natural and modified diatomite respectively. The kinetics results were found to conform well to pseudo-second order kinetics model with good correlation. Thus, this study demonstrated that the modified diatomite could be used as potential adsorbent for removal of toluene from aqueous solution.

Anaerobic treatment of blended sugar industry and ethanol distillery wastewater through biphasic high rate reactor.

PubMed

Fito, Jemal; Tefera, Nurelegne; Kloos, Helmut; Van Hulle, Stijn W H

2018-06-07

This study aimed to investigate the physicochemical properties of sugar industry and ethanol distillery wastewater and the treatment of the blended wastewater through a two-stage anaerobic reactor. For this treatment, different initial chemical oxygen demand (COD) concentrations (5-20 g/L) and hydraulic retention times (HRTs) (2-10 days) were applied. The sugar industry effluent characteristics obtained in terms of organic matter (mg/L) were as follows: 5 days biochemical oxygen demand (BOD 5 ): 654.5-1,968; COD: 1,100-2,148.9; total solids (TS): 2,467-4,012 mg/L; and pH: 6.93-8.43. The ethanol distillery spent wash strengths obtained were: BOD 5 : 27,600-42,921 mg/L; COD: 126,000-167,534 mg/L; TS: 140,160-170,000 mg/L; and pH: 3.9-4.2. Maximum COD removal of 65% was obtained at optimum condition (initial COD concentration of 10 g/L and HRT of 10 days), and maximum color removal of 79% was recorded under similar treatment conditions. Hence, the performance of the two-stage anaerobic reactor for simultaneous removal of COD and color from high-strength blended wastewater is promising for scaling up in order to mitigate environmental problems of untreated effluent discharge.

A calibration protocol of a one-dimensional moving bed bioreactor (MBBR) dynamic model for nitrogen removal.

PubMed

Barry, U; Choubert, J-M; Canler, J-P; Héduit, A; Robin, L; Lessard, P

2012-01-01

This work suggests a procedure to correctly calibrate the parameters of a one-dimensional MBBR dynamic model in nitrification treatment. The study deals with the MBBR configuration with two reactors in series, one for carbon treatment and the other for nitrogen treatment. Because of the influence of the first reactor on the second one, the approach needs a specific calibration strategy. Firstly, a comparison between measured values and simulated ones obtained with default parameters has been carried out. Simulated values of filtered COD, NH(4)-N and dissolved oxygen are underestimated and nitrates are overestimated compared with observed data. Thus, nitrifying rate and oxygen transfer into the biofilm are overvalued. Secondly, a sensitivity analysis was carried out for parameters and for COD fractionation. It revealed three classes of sensitive parameters: physical, diffusional and kinetic. Then a calibration protocol of the MBBR dynamic model was proposed. It was successfully tested on data recorded at a pilot-scale plant and a calibrated set of values was obtained for four parameters: the maximum biofilm thickness, the detachment rate, the maximum autotrophic growth rate and the oxygen transfer rate.

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.

Use of different surface covering materials to enhance removal of radiocaesium in plants and upper soil from orchards in Fukushima prefecture.

PubMed

Sato, Mamoru; Akai, Hiroko; Saito, Yuichi; Takase, Tsugiko; Kikunaga, Hidetoshi; Sekiya, Nobuhito; Ohtsuki, Tsutomu; Yamaguchi, Katsuhiko

2017-04-04

The effectiveness of a decontamination methodology whereby herbaceous plants were grown through different materials covering the soil surface followed by subsequent removal of the material, associated plant tissues and attached soil on 137 Cs removal from soil was evaluated. Revegetation netting sown with Kentucky bluegrass and white clover had a high effectiveness in 137 Cs removal when rolling up the plants, roots, and rhizosphere soil approximately 6 months after sowing. The removal rate was lower when there was higher 137 Cs vertical migration down the soil profile. The maximum removal effectiveness of 93.1% was observed by rolling up fertilized Kentucky bluegrass with a well-developed root mat without netting, indicating that applying nutrients to encourage the development of roots or root mats in the 3 cm topsoil rhizosphere is an efficient technology to increase the decontamination effect of plant removal in orchards. Netting and weeding were able to remove up to 80% of 137 Cs in the soil without the use of heavy machinery. There was a significant relationship between the removal ratio and the removed soil weight per area. Using the relationship on the site below the canopy, removal of 14.3 kg m -2 DW soil would achieve a removal ratio of 80%. The effectiveness of the technique will decrease with time as radiocaesium migrates down the soil profile but this would be expected to occur slowly in many soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lead recovery and glass microspheres synthesis from waste CRT funnel glasses through carbon thermal reduction enhanced acid leaching process.

PubMed

Mingfei, Xing; Yaping, Wang; Jun, Li; Hua, Xu

2016-03-15

In this study, a novel process for detoxification and reutilization of waste cathode ray tube (CRT) funnel glass was developed by carbon thermal reduction enhanced acid leaching process. The key to this process is removal of lead from the CRT funnel glass and synchronous preparation of glass microspheres. Carbon powder was used as an isolation agent and a reducing agent. Under the isolation of the carbon powder, the funnel glass powder was sintered into glass microspheres. In thermal reduction, PbO in the funnel glass was first reduced to elemental Pb by carbon monoxide and then located on the surface of glass microspheres which can be removed easily by acid leaching. Experimental results showed that temperature, carbon adding amount and holding time were the major parameters that controlled lead removal rate. The maximum lead removal rate was 94.80% and glass microspheres that measured 0.73-14.74μm were obtained successfully by setting the temperature, carbon adding amount and holding time at 1200°C, 10% and 30min, respectively. The prepared glass microspheres may be used as fillers in polymer materials and abrasive materials, among others. Accordingly, this study proposed a practical and economical process for detoxification and recycling of waste lead-containing glass. Copyright © 2015 Elsevier B.V. All rights reserved.

Substrate removal kinetics in high-rate upflow anaerobic filters packed with low-density polyethylene media treating high-strength agro-food wastewaters.

PubMed

Rajagopal, Rajinikanth; Torrijos, Michel; Kumar, Pradeep; Mehrotra, Indu

2013-02-15

The process kinetics for two upflow anaerobic filters (UAFs) treating high strength fruit canning and cheese-dairy wastewaters as feed were investigated. The experimental unit consisted of a 10-L (effective volume) reactor filled with low-density polyethylene media. COD removal efficiencies of about 80% were recorded at the maximum OLRs of 19 and 17 g COD L(-1) d(-1) for the fruit canning and cheese-dairy wastewaters, respectively. Modified Stover-Kincannon and second-order kinetic models were applied to data obtained from the experimental studies in order to determine the substrate removal kinetics. According to Stover-Kincannon model, U(max) and K(B) values were estimated as 109.9 and 109.7 g L(-1) d(-1) for fruit canning, and 53.5 and 49.7 g L(-1) d(-1) for cheese dairy wastewaters, respectively. The second order substrate removal rate k(2(s)) was found to be 5.0 and 1.93 d(-1) respectively for fruit canning and cheese dairy wastewaters. As both these models gave high correlation coefficients (R(2) = 98-99%), they could be used in predicting the behaviour or design of the UAF. Copyright © 2012 Elsevier Ltd. All rights reserved.

Exploratory experiments to determine the effect of alternative operations on the efficiency of subsurface arsenic removal in rural Bangladesh

NASA Astrophysics Data System (ADS)

Rahman, M. M.; Bakker, M.; Freitas, S. C. Borges; van Halem, D.; van Breukelen, B. M.; Ahmed, K. M.; Badruzzaman, A. B. M.

2015-02-01

The principle of subsurface arsenic (As) removal (SAR) is to extract anoxic groundwater, aerate it and re-inject it. Oxygen in the injected water reacts with iron in the resident groundwater to form hydrous ferric oxide (HFO). Dissolved As sorbs onto the HFO, which allows for the extraction of groundwater with lower As concentrations. SAR was applied at a rural location in Bangladesh (As in groundwater = 200 μg/L) to study the effect of different operational parameters on SAR performance, including repeated injection and extraction of an equal volume, lower pumping rate, and intermittent pumping. Larger injection volume, lower pumping rate, and intermittent pumping all had positive effects on As removal indicating that As adsorption is kinetically limited. Repeated injection-extraction of an equal volume improved As removal efficiency by providing more HFO for sorption. After injection of 1,000 L, a maximum of 3,000 L of `safe' water, as defined by the Bangladesh national standard for As (<50 μg/L), was extracted, of which 2,000 L can be used as drinking water and the remainder is used for re-injection. Under this setup, the estimated cost for 1,000 L of As-safe drinking water is US2.00, which means that SAR is a viable mitigation option for rural areas.

The effect of malathion on the activity, performance, and microbial ecology of activated sludge.

PubMed

Rauglas, Erik; Martin, Seth; Bailey, Kandace; Magnuson, Matthew; Phillips, Rebecca; Harper, Willie F

2016-12-01

This study evaluated the effect of a VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) surrogate (malathion) on the activity, performance, and ecology of activated sludge bioreactors. In the presence of malathion, the maximum observed respiration rates varied between 43 and 53 μg/O2 min, generally similar to the 49 μg O2/min rates observed in controls. Malathion did not alter the respiration ratio of O2 consumed-to-CO2 produced nor did it impact the shape of the oxygen consumption curves during respirometry. Shorter term (12 h) batch tests showed that both chemical oxygen demand (COD) and ammonia removal were not negatively impacted by the presence of 0.1-3 mg/L malathion. Longer term continuous addition (i.e. 40 days) of 0.1 mg/L of malathion also had no effect on COD and ammonia removal. In contrast to shorter term exposures, longer term continuous addition of 3 mg/L of malathion negatively impacted both COD and nitrogen removal and was associated with shifts in the abundance of species that are common to activated sludge. These results illustrate the impact that chemicals like malathion may have on COD removal, and nitrification, as well as the robustness of activated sludge microbial communities. Published by Elsevier Ltd.

A biocompatible and novelly-defined Al-HAP adsorption membrane for highly effective removal of fluoride from drinking water.

PubMed

He, Junyong; Chen, Kai; Cai, Xingguo; Li, Yulian; Wang, Chengming; Zhang, Kaisheng; Jin, Zhen; Meng, Fanli; Wang, Xuguang; Kong, Lingtao; Liu, Jinhuai

2017-03-15

A biocompatible and novelly-defined adsorption membrane for rapid removal of fluoride was prepared. Both adsorption and membrane techniques were used in this research. Al(OH) 3 nanoparticles modified hydroxyapatite (Al-HAP) nanowires were developed and made into Al-HAP membrane. The adsorption data of Al-HAP adsorbent could be well described by Freundlich isotherm model while the adsorption kinetic followed pseudo-second-order model. The maximum of adsorption capacity was 93.84mg/g when the fluoride concentration was 200mg/L. The adsorption mechanism was anion exchanges and electrostatic interactions. The contribution rates of HAP nanowires and Al(OH) 3 nanoparticles in fluoride removal were 36.70% and 63.30%, respectively. The fixed-bed column test demonstrate that the Al-HAP was biocompatible and in a good stability during the process of water treatment. The fluoride removal abilities of Al-HAP membrane with 0.3mm thickness could reach 1568L/m 2 when fluoride concentrations were 5mg/L. This study indicated that the Al-HAP membrane could be developed into a very viable technology for highly effective removal of fluoride from drinking water. Copyright © 2016 Elsevier Inc. All rights reserved.

Central Composite Design Optimization of Zinc Removal from Contaminated Soil, Using Citric Acid as Biodegradable Chelant.

PubMed

Asadzadeh, Farrokh; Maleki-Kaklar, Mahdi; Soiltanalinejad, Nooshin; Shabani, Farzin

2018-02-08

Citric acid (CA) was evaluated in terms of its efficiency as a biodegradable chelating agent, in removing zinc (Zn) from heavily contaminated soil, using a soil washing process. To determine preliminary ranges of variables in the washing process, single factor experiments were carried out with different CA concentrations, pH levels and washing times. Optimization of batch washing conditions followed using a response surface methodology (RSM) based central composite design (CCD) approach. CCD predicted values and experimental results showed strong agreement, with an R 2 value of 0.966. Maximum removal of 92.8% occurred with a CA concentration of 167.6 mM, pH of 4.43, and washing time of 30 min as optimal variable values. A leaching column experiment followed, to examine the efficiency of the optimum conditions established by the CCD model. A comparison of two soil washing techniques indicated that the removal efficiency rate of the column experiment (85.8%) closely matching that of the batch experiment (92.8%). The methodology supporting the research experimentation for optimizing Zn removal may be useful in the design of protocols for practical engineering soil decontamination applications.

Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

PubMed Central

Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

2015-01-01

This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions. PMID:26486449

Non-steady state simulation of BOM removal in drinking water biofilters: model development.

PubMed

Hozalski, R M; Bouwer, E J

2001-01-01

A numerical model was developed to simulate the non-steady-state behavior of biologically-active filters used for drinking water treatment. The biofilter simulation model called "BIOFILT" simulates the substrate (biodegradable organic matter or BOM) and biomass (both attached and suspended) profiles in a biofilter as a function of time. One of the innovative features of BIOFILT compared to previous biofilm models is the ability to simulate the effects of a sudden loss in attached biomass or biofilm due to filter backwash on substrate removal performance. A sensitivity analysis of the model input parameters indicated that the model simulations were most sensitive to the values of parameters that controlled substrate degradation and biofilm growth and accumulation including the substrate diffusion coefficient, the maximum rate of substrate degradation, the microbial yield coefficient, and a dimensionless shear loss coefficient. Variation of the hydraulic loading rate or other parameters that controlled the deposition of biomass via filtration did not significantly impact the simulation results.

Biofiltration of air contaminated by styrene vapors on inorganic filtering media: an experimental study.

PubMed

St-Pierre, Marie-Claude Dion; Avalos Ramirez, Antonio; Heitz, Michèle

2009-05-01

This paper presents a study on the biofiltration of styrene by using two inorganic filtering materials. The effects of styrene inlet load and nitrogen concentration present in the nutrient solution on biofilter performance were studied. The styrene inlet concentration was varied from 65 to 1115 parts per million by volume (ppmv), whereas the contaminated airflow rate was fixed at 1 m3/hr. The nitrogen concentration in nutrient solution was varied from 1 to 4 gN/L. The maximum elimination capacity obtained was 105 g/m3-hr, which corresponded to a removal efficiency of 80% for a styrene inlet load of 130 g/m3-hr. This study shows that the nitrogen content in the nutrient solution affects the removal rate of styrene, with an optimal nitrogen concentration of 3 gN/L. The performance comparison between two different inorganic bed types was undertaken and a comparative study on biofiltration of two aromatic compounds, styrene and toluene, is also presented.

Biological removal of nitrate and ammonium under aerobic atmosphere by Paracoccus versutus LYM.

PubMed

Shi, Zhuang; Zhang, Yu; Zhou, Jiti; Chen, Mingxiang; Wang, Xiaojun

2013-11-01

The bacterium isolated from sea sludge Paracoccus versutus LYM was characterized with the ability of aerobic denitrification. Strain LYM performs perfect activity in aerobically converting over 95% NO3(-)-N (approximate 400mg L(-1)) to gaseous products via nitrite with maximum reduction rate 33 mg NO3(-)-N L(-1) h(-1). Besides characteristic of aerobic denitrification, strain LYM was confirmed in terms of the ability to be heterotrophic nitrification and aerobic denitrification (HNAD) with few accumulations of intermediates. After the nitrogen balance and enzyme assays, the putative nitrogen pathway of HNAD could be NH4(+) → NH2OH → NO2(-)→ NO3(-), then NO3(-) was denitrified to gaseous products via nitrite. N2 was sole denitrification product without any detection of N2O by gas chromatography. Strain LYM could also simultaneously remove ammonium and additional nitrate. Meanwhile, the accumulated nitrite had inhibitory effect on ammonium reduction rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Start-up, steady state performance and kinetic evaluation of a thermophilic integrated anaerobic-aerobic bioreactor (IAAB).

PubMed

Chan, Yi Jing; Chong, Mei Fong; Law, Chung Lim

2012-12-01

Thermophilic treatment of palm oil mill effluent (POME) was studied in a novel integrated anaerobic-aerobic bioreactor (IAAB). The IAAB was subjected to a program of steady-state operation over a range of organic loading rate (OLR)s, up to 30 g COD/L day in order to evaluate its treatment capacity. The thermophilic IAAB achieved high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of more than 99% for OLR up to 18.5 g COD/L day. High methane yield of 0.32 LCH(4) (STP)/g COD(removed) with compliance of the final treated effluent to the discharge limit were achieved. This is higher than that of the mesophilic system due to the higher maximum specific growth rate (μ(max)) of the thermophilic microorganisms. Besides, coupling the model of Grau second order model (anaerobic system) with the model of Monod (aerobic system) will completely define the IAAB system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Anammox moving bed biofilm reactor pilot at the 26th Ward wastewater treatment plants in Brooklyn, New York: start-up, biofilm population diversity and performance optimization.

PubMed

Mehrdad, M; Park, H; Ramalingam, K; Fillos, J; Beckmann, K; Deur, A; Chandran, K

2014-01-01

New York City Environmental Protection in conjunction with City College of New York assessed the application of the anammox process in the reject water treatment using a moving bed biofilm reactor (MBBR) located at the 26th Ward wastewater treatment plant, in Brooklyn, NY. The single-stage nitritation/anammox MBBR was seeded with activated sludge and consequently was enriched with its own 'homegrown' anammox bacteria (AMX). Objectives of this study included collection of additional process kinetic and operating data and assessment of the effect of nitrogen loading rates on process performance. The initial target total inorganic nitrogen removal of 70% was limited by the low alkalinity concentration available in the influent reject water. Higher removals were achieved after supplementing the alkalinity by adding sodium hydroxide. Throughout startup and process optimization, quantitative real-time polymerase chain reaction (qPCR) analyses were used for monitoring the relevant species enriched in the biofilm and in the suspension. Maximum nitrogen removal rate was achieved by stimulating the growth of a thick biofilm on the carriers, and controlling the concentration of dissolved oxygen in the bulk flow and the nitrogen loading rates per surface area; all three appear to have contributed in suppressing nitrite-oxidizing bacteria activity while enriching AMX density within the biofilm.

Feasibility of using a microalgal-bacterial consortium for treatment of toxic coke wastewater with concomitant production of microbial lipids.

PubMed

Ryu, Byung-Gon; Kim, Jungmin; Han, Jong-In; Yang, Ji-Won

2017-02-01

This study examined the feasibility of using an algal-bacterial process for removal of phenol and NH 4 + -N from differently diluted coke wastewater with simultaneous production of biomass. Under illumination, microalgal-bacterial (MSB) cultures performed complete phenol degradation at all dilutions of coke wastewater while sole microalgal culture (MSA) degraded a maximum of 27.3% of phenol (initial concentration: 24.0mgL -1 ) from 5-fold diluted wastewater. Furthermore, the MSB culture had the highest rate of NH 4 + -N removal (8.3mgL -1 d -1 ) and fatty acid production (20mgL -1 d -1 ) which were 2.3- and 1.5-fold higher than those observed in the MSA cultures, probably due to decreases in toxic organic pollutants. Multivariate analyses indicated that co-cultivation of activated sludge was directly correlated with the elevated removals of phenol and NH 4 + -N. In the presence of sludge, adequate dilution of the coke wastewater can maximize the effect of bacteria on NH 4 + -N removal and biomass production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal.

PubMed

Song, Jooyoung; Oh, Hyuntaek; Kong, Hyeyoung; Jang, Jyongsik

2011-03-15

Polyrhodanine was immobilized onto the inner surface of anodic aluminum oxide (AAO) membrane via vapor deposition polymerization method. The polyrhodanine modified membrane was applied to remove heavy metal ions from aqueous solution because polyrhodanine could be coordinated with specific metal ions. Several parameters such as initial metal concentration, contact time and metal species were evaluated systematically for uptake efficiencies of the fabricated membrane under continuous flow condition. Adsorption isotherms of Hg(II) ion on the AAO-polyrhodanine membrane were analyzed with Langmuir and Freundlich isotherm models. The adsorption rate of Hg(II) ion on the membrane was obeyed by a pseudo-second order equation, indicating the chemical adsorption. The maximum removal capacity of Hg(II) ion onto the fabricated membrane was measured to be 4.2 mmol/g polymer. The AAO-polyrhodanine membrane had also remarkable uptake performance toward Ag(I) and Pb(II) ions. Furthermore, the polyrhodanine modified membrane could be recycled after recovery process. These results demonstrated that the polyrhodanine modified AAO membrane provided potential applications for removing the hazardous heavy metal ions from wastewater. Copyright © 2011 Elsevier B.V. All rights reserved.

Selection and identification of fungi isolated from sugarcane bagasse and their application for phenanthrene removal from soil.

PubMed

Cortés-Espinosa, D V; Fernández-Perrino, F J; Arana-Cuenca, A; Esparza-García, F; Loera, O; Rodríguez-Vázquez, R

2006-01-01

This work investigated the identification and selection of fungi isolated from sugarcane bagasse and their application for phenanthrene (Phe) removal from soil. Fungi were identified by PCR amplification of ITS regions as Aspergillus terrus, Aspergillus fumigatus and Aspergillus niger, Penicillium glabrum and Cladosporium cladosporioides. A primary selection of fungi was accomplished in plate, considering Phe tolerance of every strain in two different media: potato dextrose agar (PDA) and mineral medium (MM). The radial extension rate (r(r)) in PDA exhibited significant differences (p<0.05) at 200 and 400 ppm of Phe. A secondary selection of A. niger, C. cladosporoides, and P. glabrum sp. was achieved based on their tolerance to 200, 400, 600 and 800 ppm of Phe, in solid culture at a sugarcane bagasse/contaminated soil ratio of 95:5, in Toyamas, Czapeck and Wunder media. Under these conditions, a maximum (70%) Phe removal by A. niger was obtained. In addition C. cladosporioides and A. niger were able to remove high (800 ppm) Phe concentrations.

Performance of system consisting of vertical flow trickling filter and horizontal flow multi-soil-layering reactor for treatment of rural wastewater.

PubMed

Zhang, Yi; Cheng, Yan; Yang, Chunping; Luo, Wei; Zeng, Guangming; Lu, Li

2015-10-01

In order to improve nitrogen removal for rural wastewater, a novel two-stage hybrid system, consisting of a vertical flow trickling filter (VFTF) and a horizontal flow multi-soil-layering (HFMSL) bioreactor was developed. The performance of the apparatus was observed under various carbon-nitrogen ratios and water spraying frequencies separately. The maximum removal efficiency of total nitrogen (TN) for the hybrid system was 92.8% while the removal rates of CODCr, ammonium (NH4(+)-N), and total phosphorus (TP) were 94.1%, 96.1%, 92.0% respectively, and the corresponding effluent concentrations were 3.61, 21.20, 1.91, and 0.33 mg L(-1). The horizontal flow mode for MSL led the system to denitrifying satisfactorily as it ensured relatively long hydraulic retention time (HRT), ideal anoxic condition and adequate organic substrates supply. Also, higher water spraying frequency benefited intermittent feeding system for pollutants removal. Shock loading test indicated that the hybrid system could operate well even at hydraulic shock loadings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Steady- and transient-state H2S biofiltration using expanded schist as packing material.

PubMed

Romero Hernandez, A C; Rodríguez Susa, M S; Andrès, Y; Dumont, E

2013-01-25

The performances of three laboratory-scale biofilters (BF1, BF2, BF3) packed with expanded schist for H(2)S removal were studied at different empty bed residence times (EBRT=35, 24 and 16s) in terms of elimination capacity (EC) and removal efficiency (RE). BF1 and BF2 were filled with expanded schist while BF3 was filled with both expanded schist and a nutritional material (UP20; 12% vol). BF1 and BF3 were inoculated with activated sludge, whereas BF2 was not inoculated. A maximum EC of 42 g m(-3) h(-1) was recorded for BF3 at EBRT=35 s demonstrating the ability of schist to treat high H(2)S loading rates, and the ability of UP20 to improve H(2)S removal. Michaelis-Menten and Haldane models were fitted to the experimental elimination capacities while biofilter responses to transient-state conditions in terms of removal efficiency during shock load events were also evaluated for BF1 and BF3. Copyright © 2012 Elsevier B.V. All rights reserved.

Features of Golenkinia sp. and microbial fuel cells used for the treatment of anaerobically digested effluent from kitchen waste at different dilutions.

PubMed

Hou, Qingjie; Cheng, Juan; Nie, Changliang; Pei, Haiyan; Jiang, Liqun; Zhang, Lijie; Yang, Zhigang

2017-09-01

The aim of this work was to study Golenkinia sp. and microbial fuel cells (MFCs) for the treatment of anaerobically digested effluent from kitchen waste (ADE-KW) with different dilution factors. A dual-chamber MFC was fabricated for treating ADE-KW in the two chambers of the MFC and harvesting Golenkinia sp. All the anodic TN was removed more than 80%. COD removal efficiency increased from 48.2% to 76% when the dilution factor increased from 1 to 4. Maximum COD and TN removal rates were 3.56 and 3.71mg·L -1 ·h -1 when ADE-KW was treated without dilution in the anodic chamber. All the cathodic TN and TP removal efficiencies were approximately 90%. The highest open circuit voltage (OCV) and power density were approximately 400mV and 400mW when ADE-KW was treated directly (undiluted) in the MFC, with the highest biomass and total lipid content production of Golenkinia sp. in the cathodic chamber. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improvement of the degradation of sulfate rich wastewater using sweetmeat waste (SMW) as nutrient supplement.

PubMed

Das, Bidus Kanti; Roy, Shantonu; Dev, Subhabrata; Das, Debabrata; Bhattacharya, Jayanta

2015-12-30

External dosing of sweetmeat waste (SMW) dosing into exhausted upflow packed bed bioreactor (PBR) resulted in prompt reactivation of SO4(2-) removal. Different SMW concentrations in terms of chemical oxygen demand (COD)/SO4(2-) ratios (1, 2, 4 and 8) were introduced into four identical PBR where process stability was found within 3 weeks of operation. SO4(2-) removal was proportional to COD/SO4(2-) ratios up to 4 at which maximum sulfate removal (99%) was achieved at a rate of 607 mg/d. The value of COD consumption:SO4(2-)removal was much higher at ratio 4 than 8 whereas, ratio 2 was preferred over all. Net effluent acetate concentration profile and total microbial population attached to the reactor matrices were corresponding to COD/SO4(2-) ratio as 4>8>2>1. Sulfate reducing bacteria (SRB) population was found to be inversely proportional to COD/SO4(2-) ratio in which acetate oxidizing SRB and fermentative bacteria were the dominant. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of amino acids on lipid production and nutrient removal by Rhodotorula glutinis cultivation in starch wastewater.

PubMed

Liu, Meng; Zhang, Xu; Tan, Tianwei

2016-10-01

In this paper, the components of amino acids in mixed starch wastewater (corn steep water/corn gluten water=1/3, v/v) were analyzed by GC-MS. Effects of amino acids on lipid production by Rhodotorula glutinis and COD removal were studied. The results showed that mixed starch wastewater contained 9 kinds of amino acids and these amino acids significantly improved the biomass (13.63g/L), lipid yield (2.48g/L) and COD removal compared to the basic medium (6.23g/L and 1.56g/L). In a 5L fermentor containing mixed starch wastewater as substrate to culture R. glutinis, the maximum biomass, lipid content and lipid yield reached 26.38g/L, 28.90% and 7.62g/L, with the associated removal rates of COD, TN and TP reaching 77.41%, 69.12% and 73.85%, respectively. The results revealed a promising approach for lipid production with using amino acids present in starch wastewater as an alternative nitrogen source. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of multi response in end milling process of ASSAB XW-42 tool steel with liquid nitrogen cooling using Taguchi-grey relational analysis

NASA Astrophysics Data System (ADS)

Norcahyo, Rachmadi; Soepangkat, Bobby O. P.

2017-06-01

A research was conducted for the optimization of the end milling process of ASSAB XW-42 tool steel with multiple performance characteristics based on the orthogonal array with Taguchi-grey relational analysis method. Liquid nitrogen was applied as a coolant. The experimental studies were conducted under varying the liquid nitrogen cooling flow rates (FL), and the end milling process variables, i.e., cutting speed (Vc), feeding speed (Vf), and axial depth of cut (Aa). The optimized multiple performance characteristics were surface roughness (SR), flank wear (VB), and material removal rate (MRR). An orthogonal array, signal-to-noise (S/N) ratio, grey relational analysis, grey relational grade, and analysis of variance were employed to study the multiple performance characteristics. Experimental results showed that flow rate gave the highest contribution for reducing the total variation of the multiple responses, followed by cutting speed, feeding speed, and axial depth of cut. The minimum surface roughness, flank wear, and maximum material removal rate could be obtained by using the values of flow rate, cutting speed, feeding speed, and axial depth of cut of 0.5 l/minute, 109.9 m/minute, 440 mm/minute, and 0.9 mm, respectively.

Outstanding adsorption performance of high aspect ratio and super-hydrophobic carbon nanotubes for oil removal.

PubMed

Kayvani Fard, Ahmad; Mckay, Gordon; Manawi, Yehia; Malaibari, Zuhair; Hussien, Muataz A

2016-12-01

Oil removal from water is a highly important area due to the large production rate of emulsified oil in water, which is considered one of the major pollutants, having a negative effect on human health, environment and wildlife. In this study, we have reported the application of high quality carbon nanotube bundles produced by an injected vertical chemical vapor deposition (IV-CVD) reactor for oil removal. High quality, bundles, super hydrophobic, and high aspect ratio carbon nanotubes were produced. The average diameters of the produced CNTs ranged from 20 to 50 nm while their lengths ranged from 300 to 500 μm. Two types of CNTs namely, P-CNTs and C-CNTs, (Produced CNTs from the IV-CVD reactor and commercial CNTs) were used for oil removal from water. For the first time, thermogravimetric analysis (TGA) was conducted to measure maximum oil uptake using CNT and it was found that P-CNT can take oil up to 17 times their weight. The effect of adsorbent dosage, contact time, and agitation speed were examined on the oil spill clean-up efficiency using batch sorption experiments. Higher efficiency with almost 97% removal was achieved using P-CNTs compared to 87% removal using C-CNTs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Water decontamination containing nitrate using biosorption with Moringa oleifera in dynamic mode.

PubMed

Paixão, Rebecca Manesco; Reck, Isabela Maria; Gomes, Raquel Guttierres; Bergamasco, Rosângela; Vieira, Marcelo Fernandes; Vieira, Angélica Marquetotti Salcedo

2018-05-20

This study was conducted to assess the feasibility of using Moringa oleifera Lam. (MO) seeds in the biosorption of nitrate present in aqueous solutions by means of batch and fixed-bed column biosorption processes. The batch assays showed that nitrate biosorption is enhanced under experimental conditions of pH 3 and a biosorbent mass of 0.05 g. For the experiments in dynamic mode, the results obtained from the statistical parameters showed that lesser pH, lesser feed flow rate, and higher initial concentration will result in an increase of the maximum capacity of the bed. These conditions were confirmed by experimental analysis. The best experimental conditions, according to the values for percentage removal (91.09%) and maximum capacity (7.69 mg g -1 ) of the bed, were those used in assay 1, which utilized pH 3, feed flow rate of 1 mL min -1 , and initial nitrate concentration of 100 mg L -1 .

Removal of nanoaerosol during the bubbling of the salt melt of beryllium and lithium fluorides for the preparation of reactor radioisotopes

NASA Astrophysics Data System (ADS)

Zagnit'ko, A. V.; Chuvilin, D. Yu.

2010-06-01

The parameters of aerosol particles formed in the course of the spontaneous thermal condensation of vapors and bubbling a 66LiF-34BeF2 (mol %) eutectic salt mixture with helium have been studied. For this purpose, a vertical bubbling mode at T ≈ 900 K and an ampule device for obtaining reactor radioisotopes for medical applications were used. The rate of the bulk removal and the chemical composition of aerosols were measured. The size distribution of the aerosol particles was bimodal, and the mass concentration of the particles exceeded by far the maximum permissible concentration (MPC). The characteristics of regenerated nickel multilayer nanofilters for ultrahigh filtration of aerosols from the salt liquid melt were analyzed.

Removal of oxytetracycline from aqueous solutions by hydroxyapatite as a low-cost adsorbent

NASA Astrophysics Data System (ADS)

Harja, Maria; Ciobanu, Gabriela

2017-11-01

The present paper involved a study of the adsorption process of the oxytetracycline drug from aqueous medium by using the hydroxyapatite nanopowders as adsorbent materials. The batch adsorption experiments were performed by monitoring the solution pH, contact time, adsorbent dosage and drug solution concentration. At pH 8 and ambient temperature, high oxytetracycline removal rates of about 97.58% and 89.95% for the uncalcined and calcined nanohydroxyapatites, respectively, were obtained. The kinetic studies indicate that the oxytetracycline adsorption onto nanohydroxyapatite samples follows a pseudo-second order kinetic model. The maximum adsorption capacities of 291.32 mg/g and 278.27 mg/g for uncalcined and calcined nanohydroxyapatite samples, respectively, have been found. So, the conclusion can be drawn that the hydroxyapatite shows good adsorption ability towards oxytetracycline.

Scaled-up dual anode/cathode microbial fuel cell stack for actual ethanolamine wastewater treatment.

PubMed

An, Byung-Min; Heo, Yoon; Maitlo, Hubdar-Ali; Park, Joo-Yang

2016-06-01

The aim of this work was to develop the scale-up microbial fuel cell technology for actual ethanolamine wastewater treatment, dual anode/cathode MFC stacks connected in series to achieve any desired current, treatment capacity, and volume capacity. However, after feeding actual wastewater into the MFC, maximum power density decreased while the corresponding internal resistance increased. With continuous electricity production, a stack of eight MFCs in series achieved 96.05% of COD removal and 97.30% of ammonia removal at a flow rate of 15.98L/d (HRT 12h). The scaled-up dual anode/cathode MFC stack system in this research was demonstrated to treat actual ETA wastewater with the added benefit of harvesting electricity energy. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

The fate of chlorinated aliphatics in anaerobic treatment under transient loading

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

Chiu, Y.C.

1993-01-01

A CSTR with dispersed-growth anaerobic bacteria that simultaneously remove COD and chlorinated aliphatics was used. Seven chlorinated aliphatics (methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, 1,1-dichloroethylene, trichloroethylene, and tetrachloroethylene) were biotransformed into lower-chlorinated compounds by anaerobic treatment, utilizing propionic acid (HPr) or acetic acid (HAc). The microorganisms supplied with HAc grew and were sustained at higher BSS concentrations (4,500 to 11,000 mg/L) than those with HPr (2,000 to 5,000 mg/L). The anaerobic treatment process has a considerable potential for acclimation to and biotransformation of toxic chlorinated aliphatics. For providing a safe operation range, the maximum loading rates of the chlorinated aliphaticsmore » are defined as the observed daily injection of those compounds which resulted in 50% activity of the biomass. Based on the reactor volume, the maximum chlorinated compound loading rates to the microorganisms metabolizing HPr were from 0.4 to 90 mg/L-day, while the rates ranged from 0.6 to 190 mg/L-day for the microorganisms metabolizing HAc. When based on biomass, the maximum loading rates of the microorganisms metabolizing HPr were from 0.2 to 26 mg/g cell-day, while rates for the microorganisms metabolizing HAc ranged from 0.1 to 19 mg/g cell-day. Anaerobic microorganisms have higher resistance to chlorinated aliphatic alkenes than alkanes, and can biotransform about 0.04 to 68 pound chlorinated aliphatics while simultaneously metabolizing 1,000 pounds COD. Therefore, within the safe operation range, the anaerobic process can stabilize organic pollution at a high rate while still biotransforming chlorinated aliphatics.« less

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.

[Removal and Recycle of Phosphor from Water Using Magnetic Core/Shell Structured Fe₃O₄ @ SiO₂Nanoparticles Functionalized with Hydrous Aluminum Oxide].

PubMed

Lai, Li; Xie, Qiang; Fang, Wen-kan; Xing, Ming-chao; Wu, De-yi

2016-04-15

A novel magnetic core/shell structured nano-particle Fe₃O₄@ SiO₂phosphor-removal ahsorbent functionalized with hydrous aluminum oxides (Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O) was synthesized. Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O was characterized by XRD, TEM, VSM and BET nitrogen adsorption experiment. The XRD and TEM results demonstrated the presence of the core/shell structure, with saturated magnetization and specific surface area of 56.00 emu · g⁻¹ and 47.27 m² · g⁻¹, respectively. In batch phosphor adsorption experiment, the Langmuir adsorption maximum capacity was 12.90 mg · g⁻¹ and nearly 96% phosphor could be rapidly removed within a contact time of 40 mm. Adsorption of phosphor on Fe₃O₄@ SiO₂@ Al₂O₃ · nH₂O was highly dependent on pH condition, and the favored pH range was 5-9 in which the phosphor removal rate was above 90%. In the treatment of sewage water, the recommended dosage was 1.25 kg · t⁻¹. In 5 cycles of adsorption-regeneration-desorption experiment, over 90% of the adsorbed phosphor could be desorbed with 1 mol · L⁻¹ NaOH, and Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O could be reused after regeneration by pH adjustment with slightly decreased phosphor removal rate with increasing recycling number, which proved the recyclability of Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O and thereby its potential in recycling of phosphor resources.

Novel cavitation fluid jet polishing process based on negative pressure effects.

PubMed

Chen, Fengjun; Wang, Hui; Tang, Yu; Yin, Shaohui; Huang, Shuai; Zhang, Guanghua

2018-04-01

Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP. Copyright © 2017 Elsevier B.V. All rights reserved.

Phytoremediation Potential of Duckweed (Lemna minor L.) On Steel Wastewater.

PubMed

Saha, Priyanka; Banerjee, Angela; Sarkar, Supriya

2015-01-01

An eco-friendly and cost effective technique- phytoremediation was used to remediate contaminants from waste water. This study demonstrated that phytoremediation ability of duckweed (Lemna minor L.) to remove chloride, sulphate from Biological Oxygen Treatment (BOT) waste water of coke oven plant. The BOT water quality was assessed by analyzing physico-biochemical characters--pH, Biological oxygen demand (BOD), Chemical oxygen demand (COD), total dissolved solids (TDS) and elemental concentration. It was observed that an increase in pH value indicated an improvement of water quality. The experimental results showed that, duckweed effectively removed 30% chloride, 16% sulphate and 14% TDS from BOT waste water, which suggested its ability in phytoremediation for removal of chloride and sulphate from BOT waste water. A maximum increase of 30% relative growth rate of duckweed was achieved after 21 days of experiment. Thus, it was concluded that duckweed, an aquatic plant, can be considered for treatment of the effluent discharged from the coke oven plant.

Pecan nutshell as biosorbent to remove Cu(II), Mn(II) and Pb(II) from aqueous solutions.

PubMed

Vaghetti, Julio C P; Lima, Eder C; Royer, Betina; da Cunha, Bruna M; Cardoso, Natali F; Brasil, Jorge L; Dias, Silvio L P

2009-02-15

In the present study we reported for the first time the feasibility of pecan nutshell (PNS, Carya illinoensis) as an alternative biosorbent to remove Cu(II), Mn(II) and Pb(II) metallic ions from aqueous solutions. The ability of PNS to remove the metallic ions was investigated by using batch biosorption procedure. The effects such as, pH, biosorbent dosage on the adsorption capacities of PNS were studied. Four kinetic models were tested, being the adsorption kinetics better fitted to fractionary-order kinetic model. Besides that, the kinetic data were also fitted to intra-particle diffusion model, presenting three linear regions, indicating that the kinetics of adsorption should follow multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. Taking into account a statistical error function, the data were best fitted to Sips isotherm model. The maximum biosorption capacities of PNS were 1.35, 1.78 and 0.946mmolg(-1) for Cu(II), Mn(II) and Pb(II), respectively.

Diatomite Modified Immobilized Delftia sp. for the Bio-Abiotic Removal of Antibiotics Amoxicillin in the Aqueous System

NASA Astrophysics Data System (ADS)

Gao, Lijuan; Sun, Jing; Guan, Kai; Shen, Tingting; Wang, Xikui

2017-05-01

Diatomite modified sodium alginate (Si/SA) immobilized Delftia sp. A2(2011) (STT01) was applied to degrade amoxicillin. The immobilized pellets provided a direct and visual probe for the degradation process due to their intrinsic bright colour. The results demonstrated that 100% of amoxicillin and 68.5% of CODcr removal were achieved after 72 h, comparing with the cases of sodium alginate (SA) system (81.2%, 46.9%) and the free cells system (60.5%, 35.5%). The degradation kinetics was in good agreement with Michaelis-Menten equation. The maximum rate (Vm ) and Michaelis constant (Km ) were calculated as 9.09 mg L-1 h-1 and 228 mg L-1, respectively. The results further revealed that diatomite not only acted as immobilization support to improve the mechanical strength and lifetime of the pellets but also as absorbent to promote the treatment efficiency. Therefore, both enzymatic catalysis and chemisorption were responsible for the removal of amoxicillin.

Influence of sludge age on the performance of MFC treating winery wastewater.

PubMed

Penteado, Eduardo D; Fernandez-Marchante, Carmen Maria; Zaiat, Marcelo; Cañizares, Pablo; Gonzalez, Ernesto Rafael; Rodrigo, Manuel Andrés

2016-05-01

The objective of this paper was to determine the influence of sludge age on microbial fuel cell (MFC) performance for generating electricity and removing organic matter from winery wastewater. Six Solid Retention Times (SRT) were used: 1.2, 1.4, 1.8, 2.3, 3.5 and 7.0 d. Results demonstrate that the electricity generation increases by decreasing the SRT, selecting electrogenic microorganisms, once the specific organic loading rate (SOLR) increased and the competition for substrate was reduced. Decreasing the SRT, coulombic efficiency can be increased from 3.4% to almost 42.2% and maximum power density from 58 to 890 mW m(-2). However the SRT did not influence on organic matter removal in biological treatment, because only a small part of COD was removed oscillating around 600 mg L(-1) d(-1)and it was very similar at all SRT studied. Copyright © 2016 Elsevier Ltd. All rights reserved.

Robust motion artefact resistant circuit for calculation of Mean Arterial Pressure from pulse transit time.

PubMed

Bhattacharya, Tinish; Gupta, Ankesh; Singh, Salam ThoiThoi; Roy, Sitikantha; Prasad, Anamika

2017-07-01

Cuff-less and non-invasive methods of Blood Pressure (BP) monitoring have faced a lot of challenges like stability, noise, motion artefact and requirement for calibration. These factors are the major reasons why such devices do not get approval from the medical community easily. One such method is calculating Blood Pressure indirectly from pulse transit time (PTT) obtained from electrocardiogram (ECG) and Photoplethysmogram (PPG). In this paper we have proposed two novel analog signal conditioning circuits for ECG and PPG that increase stability, remove motion artefacts, remove the sinusoidal wavering of the ECG baseline due to respiration and provide consistent digital pulses corresponding to blood pulses/heart-beat. We have combined these two systems to obtain the PTT and then correlated it with the Mean Arterial Pressure (MAP). The aim was to perform major part of the processing in analog domain to decrease processing load over microcontroller so as to reduce cost and make it simple and robust. We have found from our experiments that the proposed circuits can calculate the Heart Rate (HR) with a maximum error of ~3.0% and MAP with a maximum error of ~2.4% at rest and ~4.6% in motion.

Characterization of primary thermal degradation features of lignocellulosic biomass after removal of inorganic metals by diverse solvents.

PubMed

Eom, In-Yong; Kim, Kwang-Ho; Kim, Jae-Young; Lee, Soo-Min; Yeo, Hwan-Myung; Choi, In-Gyu; Choi, Joon-Weon

2011-02-01

Poplar wood powders were treated with distilled water, tap water, HCl and HF, respectively, to remove inorganics from the biomass and to investigate effect of demineralization processes on pyrolysis behavior of the biomass. TG and DTG revealed that maximum degradation temperatures rose slightly from 362°C for control to 372°C, 366°C and 368°C after demineralization with distilled water, HCl and HF, respectively. Maximum degradation rates also increased from 0.96%/°C for control to 1.15%/°C for HF-biomass, 1.23%/°C for DI-H(2)O-biomass, and 1.55%/°C for HCl-biomass. Analytical pyrolysis-GC/MS of demineralized biomasses produced approximately 45 pyrolysis compounds. Total amount of low molecular weight compounds, such as acetic acid, acetol, and 3-hydroxypropanal, was significantly lowered in the demineralized biomasses. But levoglucosan increased 2-10-folds in the demineralized biomasses. One of the features regarding lignin derivatives was the reduction of the amount of C6-type phenols, such as phenol, guaiacol, and syringol after demineralization. Copyright © 2010 Elsevier Ltd. All rights reserved.

40 CFR 280.64 - Free product removal.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Free product removal. 280.64 Section... Substances § 280.64 Free product removal. At sites where investigations under § 280.62(a)(6) indicate the presence of free product, owners and operators must remove free product to the maximum extent practicable...

Wastewater microalgal production, nutrient removal and physiological adaptation in response to changes in mixing frequency.

PubMed

Sutherland, Donna L; Turnbull, Matthew H; Broady, Paul A; Craggs, Rupert J

2014-09-15

Laminar flows are a common problem in high rate algal ponds (HRAP) due to their long channels and gentle mixing by a single paddlewheel. Sustained laminar flows may modify the amount of light microalgal cells are exposed to, increase the boundary layer between the cell and the environment and increase settling out of cells onto the pond bottom. To date, there has been little focus on the effects of the time between mixing events (frequency of mixing) on the performance of microalgae in wastewater treatment HRAPs. This paper investigates the performance of three morphologically distinct microalgae in wastewater treatment high rate algal mesocosms operated at four different mixing frequencies (continuous, mixed every 45 min, mixed every 90 min and no mixing). Microalgal performance was measured in terms of biomass concentration, nutrient removal efficiency, light utilisation and photosynthetic performance. Microalgal biomass increased significantly with increasing mixing frequency for the two colonial species but did not differ for the single celled species. All three species were more efficient at NH4-N uptake as the frequency of mixing increased. Increased frequency of mixing supported larger colonies with improved harvest-ability by gravity but at the expense of efficient light absorption and maximum rate of photosynthesis. However, maximum quantum yield was highest in the continuously mixed cultures due to higher efficiency of photosynthesis under light limited conditions. Based on these results, higher microalgal productivity, improved wastewater treatment and better gravity based harvest-ability can be achieved with the inclusion of more mixing points and reduced laminar flows in full-scale HRAP. Copyright © 2014 Elsevier Ltd. All rights reserved.

Heterotrophic nitrogen removal by Acinetobacter sp. Y1 isolated from coke plant wastewater.

PubMed

Liu, YuXiang; Hu, Tingting; Song, Yujie; Chen, Hongping; Lv, YongKang

2015-11-01

A strain of Acinetobacter sp. Y1, which exhibited an amazing ability to remove ammonium, nitrite and nitrate, was isolated from the activated sludge of a coking wastewater treatment plant. The aim of this work was to study the ability, influence factors and possible pathway of nitrogen removal by Acinetobacter sp. Y1. Results showed that maximum removal rate of NH4(+)-N by the strain was 10.28 mg-N/L/h. Carbon source had significant influence on the growth and ammonium removal efficiencies of strain Y1. Pyruvate, citrate and acetate were favourable carbon sources for the strain. Temperature, pH value and shaking speed could affect the growth and nitrogen removal ability. Nitrate or nitrite could be used as a sole nitrogen source for the growth and removed efficiently by the strain. N2 levels increased to 53.74%, 50.21% and 55.13% within 36 h when 100 mg/L NH4(+)-N, NO2(-)-N or NO3(-) -N was used as sole nitrogen source in the gas detection experiment. The activities of hydroxylamine oxidoreductase (HAO), nitrate reductase (NR) and nitrite reductase (NiR), which are key enzymes in heterotrophic nitrification and aerobic denitrification, were all detectable in the strain. Consequently, a possible pathway for ammonium removal by the strain was also suggested. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Ca and Fe modified biochars as adsorbents of arsenic and chromium in aqueous solutions.

PubMed

Agrafioti, Evita; Kalderis, Dimitrios; Diamadopoulos, Evan

2014-12-15

This work investigated the production of Ca and Fe modified biochars in order to use them for the removal of arsenic As(V) and chromium Cr(VI) from aqueous solutions. Rice husk was impregnated with CaO at an impregnation ratio 0.114, while both rice husk and the organic fraction of municipal solid wastes were impregnated with Fe(0) and Fe(3+) at impregnation ratios 0.114 and 0.23. The modified biochars exhibited high As(V) removal capacity (>95%), except for the case of rice husk impregnated with Fe(0), whose removal capacity reached only 58%. All modified biochars exhibited much better As(V) removal capacity compared to the non-impregnated biochars. However, the Cr(VI) removal rates were not as high as the As(V) ones. The maximum Cr(VI) removal was observed in the case of rice husk biochar impregnated with 2.3% w/w Fe(3+), whereas the majority of impregnation agents examined did not manage to enhance the biochars' Cr(VI) removal ability. The equilibrium study showed that the Freundlich model can adequately describe the sorption process for the majority of samples examined. Analysis of the amount of Fe present in the equilibrium solutions suggested that the main mechanisms of As(V) and Cr(VI) removal were possibly metal precipitation and electrostatic interactions between the modified biochars and the adsorbate. Copyright © 2014 Elsevier Ltd. All rights reserved.

Removal of acetaminophen in water by laccase immobilized in barium alginate.

PubMed

Ratanapongleka, Karnika; Punbut, Supot

2018-02-01

This research has focused on the optimization of immobilized laccase condition and utilization in degradation of acetaminophen contaminated in aqueous solution. Laccase from Lentinus polychrous was immobilized in barium alginate. The effects of laccase immobilization such as sodium alginate concentration, barium chloride concentration and gelation time were studied. The optimal conditions for immobilization were sodium alginate 5% (w/v), barium chloride 5% (w/v) and gelation time of 60 min. Immobilized laccase was then used for acetaminophen removal. Acetaminophen was removed quickly in the first 50 min. The degradation rate and percentage of removal increased when the enzyme concentration increased. Immobilized laccase at 0.57 U/g-alginate showed the maximum removal at 94% in 240 min. The removal efficiency decreased with increasing initial acetaminophen concentration. The K m value for immobilized laccase (98.86 µM) was lower than that of free laccase (203.56 µM), indicating that substrate affinity was probably enhanced by immobilization. The immobilized enzyme exhibited high activity and good acetaminophen removal at pH 7 and temperature of 35°C. The activation energies of free and immobilized laccase for degradation of acetaminophen were 8.08 and 17.70 kJ/mol, respectively. It was also found that laccase stability to pH and temperature increased after immobilization. Furthermore, immobilized laccase could be reused for five cycles. The capability of removal and enzyme activity were retained above 70%.

Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

NASA Technical Reports Server (NTRS)

Fisher, John W.; Abraham, Martin

1993-01-01

The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

Removal of hydrogen sulfide by sulfate-resistant Acidithiobacillus thiooxidans AZ11.

PubMed

Lee, Eun Young; Lee, Nae Yoon; Cho, Kyung-Suk; Ryu, Hee Wook

2006-04-01

Toxic H2S gas is an important industrial pollutant that is applied to biofiltration. Here, we examined the effects of factors such as inlet concentration and space velocity on the removal efficiency of a bacterial strain capable of tolerating high sulfate concentrations and low pH conditions. We examined three strains of Acidithiobacillus thiooxidans known to have sulfur-oxidizing activity, and identified strain AZ11 as having the highest tolerance for sulfate. A. thiooxidans AZ11 could grow at pH 0.2 in the presence of 74 g l(-1) sulfate, the final oxidation product of elemental sulfur, in the culture broth. Under these conditions, the specific sulfur oxidation rate was 2.9 g-S g-DCW (dry cell weight)(-1) d(-1). The maximum specific sulfur oxidation rate of A. thiooxidans AZ11 was 21.2 g-S g-DCW(-1) d(-1), which was observed in the presence of 4.2 g-SO4(2-) l(-1) and pH 1.5, in the culture medium. To test the effects of various factors on biofiltration by this strain, A. thiooxidans AZ11 was inoculated into a porous ceramic biofilter. First, a maximum inlet loading of 670 g-S m(-3) h(-1) was applied with a constant space velocity (SV) of 200 h(-1) (residence time, 18 s) and the inlet concentration of H2S was experimentally increased from 200 ppmv to 2200 ppmv. Under these conditions, less than 0.1 ppmv H2S was detected at the biofilter outlet. When the inlet H2S was maintained at a constant concentration of 200 ppmv and the SV was increased from 200 h(-1) to 400 h(-1) (residence time, 9 s), an H2S removal of 99.9% was obtained. However, H2S removal efficiencies decreased to 98% and 94% when the SV was set to 500 h(-1) (residence time, 7.2 s) and 600 h(-1) (residence time, 6 s), respectively. The critical elimination capacity guaranteeing 96% removal of the inlet H2S was determined to be 160 g-S m(-3) h(-1) at a space velocity of 600 h(-1). Collectively, these findings show for the first time that a sulfur oxidizing bacterium has a high sulfate tolerance and a high sulfur oxidizing activity below pH 1.

Analysis and comparison of biotreatment of air polluted with ethanol using biofiltration and biotrickling filtration.

PubMed

Morotti, Karine; Ramirez, Antonio Avalos; Jones, J Peter; Heitz, Michèle

2011-12-01

This study analyses the performance of ethanol biofiltration with percolation (biotrickling filtration, BTF) comparing to a conventional biofilter (biofiltration, BF). Two biofilters packed with clay balls were operated in a range of inlet concentrations of ethanol in the air varying from 0.47 to 2.36 g m(-3). For both the BF and BTF, the specific growth rate (mu) and the elimination capacity (EC) decreased with the ethanol inlet concentration, presenting a kinetic of substrate inhibition. A Haldane-type model was adjusted for both biofilters in order to model both EC and mu as a function of the ethanol inlet concentration in the gas. The maximum EC was similar for both biofilters, at around 46 g m(-3) h(-1), whereas the maximum mu was 0.0057 h(-1) for the BF and 0.0103 h(-1) for the BTF. The maximum of ethanol removed, occurred at the lowest inlet concentration of (0.47 gm(-3)), and reached 86% for the BF and 74% for the BTF.

Nanoscale zero valent supported by Zeolite and Montmorillonite: Template effect of the removal of lead ion from an aqueous solution.

PubMed

Arancibia-Miranda, Nicolás; Baltazar, Samuel E; García, Alejandra; Muñoz-Lira, Daniela; Sepúlveda, Pamela; Rubio, María A; Altbir, Dora

2016-01-15

In this work, we have studied the Pb(2+) sorption capacity of Zeolite (Z) and Montmorillonite (Mt) functionalized with nanoscale zero-valent iron (nZVI), at 50% w/w, obtained by means of an impregnating process with a solvent excess. The composites were characterized by several techniques including X-ray diffraction; scanning electron microscopy (SEM); BET area; isoelectric point (IEP); and, finally a magnetic response. Comparatively significant differences in terms of electrophoretic and magnetic characteristics were found between the pristine materials and the composites. Both structures show a high efficiency and velocity in the removal of Pb(2+) up to 99.0% (200.0 ppm) after 40 min of reaction time. The removal kinetics of Pb(2+) is adequately described by the pseudo second-order kinetic model, and the maximum adsorbed amounts (q(e)) of this analyte are in close accordance with the experimental results. The intraparticle diffusion model shows that this is not the only rate-limiting step, this being the Langmuir model which was well adjusted to our experimental data. Therefore, maximum sorption capacities were found to be 115.1±11.0, 105.5±9.0, 68.3±1.3, 54.2±1.3, and 50.3±4.2 mg g(-1), for Mt-nZVI, Z-nZVI, Zeolite, Mt, and nZVI, respectively. The higher sorption capacities can be attributed to the synergetic behavior between the clay and iron nanoparticles, as a consequence of the clay coating process with nZVI. These results suggest that both composites could be used as an efficient adsorbent for the removal of lead from contaminated water sources. Copyright © 2015 Elsevier B.V. All rights reserved.

Tartrazine modified activated carbon for the removal of Pb(II), Cd(II) and Cr(III).

PubMed

Monser, Lotfi; Adhoum, Nafaâ

2009-01-15

A two in one attempt for the removal of tartrazine and metal ions on activated carbon has been developed. The method was based on the modification of activated carbon with tartrazine then its application for the removal of Pb(II), Cd(II) and Cr(III) ions at different pH values. Tartrazine adsorption data were modelled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacities qm were 121.3, 67 and 56.7mgg(-1) at initial pH values of 1.0, 6.0 and 10, respectively. The adsorption of tartrazine onto activated carbon followed second-order kinetic model. The equilibrium time was found to be 240min at pH 1.0 and 120min at pH 10 for 500mgL(-1) tartrazine concentration. A maximum removal of 85% was obtained after 1h of contact time. The presence of tartrazine as modifier enhances attractive electrostatic interactions between metal ions and carbon surface. The adsorption capacity for Pb(II), Cd(II) and Cr(III) ions has been improved with respect to non-modified carbon reaching a maximum of 140%. The adsorption capacity was found to be a pH dependent for both modified and non-modified carbon with a greater adsorption at higher pH values except for Cr(III). The enhancement percent of Pb(II), Cd(II) and Cr(III) at different pH values was varied from 28% to 140% with respect to non-modified carbon. The amount of metal ions adsorbed using static regime was 11-40% higher than that with dynamic mode. The difference between adsorption capacities could be attributed to the applied flow rate.

Phosphate Removal by Anion Binding on Functionalized Nanoporous Sorbents

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

Chouyyok, Wilaiwan; Wiacek, Robert J.; Pattamakomsan, Kanda

2010-03-26

Phosphate was captured from aqueous solutions by cationic metal-EDA complexes anchored inside mesoporous silica MCM-41 supports (Cu(II)-EDA-SAMMS and Fe(III)-EDA-SAMMS). Fe-EDA-SAMMS was more effective at capturing phosphate than the Cu-EDA-SAMMS and was further studied for matrix effects (e.g., pH, ionic strength, and competing anions) and sorption performance (e.g., capacity and rate). The adsorption of phosphate was highly pH dependent; it increased with increasing pH from 1.0 to 6.5, and decreased above pH 6.5. The adsorption was affected by high ionic strength (0.1 M of NaCl). In the presence of 1000-fold molar excess of chloride and nitrate anions, phosphate removal by Fe-EDA-SAMMSmore » was not affected. Slight, moderate and large impacts were seen with bicarbonate, sulfate and citrate anions, respectively. The phosphate adsorption data on Fe-EDA-SAMMS agreed well with the Langmuir model with the estimated maximum capacity of 43.3 mg/g. The material displayed rapid sorption rate (99% of phosphate removal within 1 min) and lowering the phosphate content to ~ 10 µg/L of phosphorus, which is lower than the EPA’s established freshwater contaminant level for phosphorous (20 µg/L).« less

Preparation of new diatomite-chitosan composite materials and their adsorption properties and mechanism of Hg(II).

PubMed

Fu, Yong; Xu, Xiaoxu; Huang, Yue; Hu, Jianshe; Chen, Qifan; Wu, Yaoqing

2017-12-01

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet-visible (UV-Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g -1 .

Preparation of new diatomite–chitosan composite materials and their adsorption properties and mechanism of Hg(II)

PubMed Central

Fu, Yong; Xu, Xiaoxu; Huang, Yue; Hu, Jianshe; Chen, Qifan; Wu, Yaoqing

2017-01-01

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet–visible (UV–Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g−1. PMID:29308226

New design of a cathode flow-field with a sub-channel to improve the polymer electrolyte membrane fuel cell performance

NASA Astrophysics Data System (ADS)

Wang, Yulin; Yue, Like; Wang, Shixue

2017-03-01

The cathode flow-field design of polymer electrolyte membrane (PEM) fuel cells determines the distribution of reactant gases and the removal of liquid water. A suitable design can result in perfect water management and thus high cell performance. In this paper, a new design for a cathode flow-field with a sub-channel was proposed and had been experimentally analyzed in a parallel flow-field PEM fuel cell. Three sub-channel inlets were placed along the cathode channel. The main-channel inlet was fed with moist air to humidify the membrane and maintain high proton conductivity, whereas, the sub-channel inlet was fed with dry air to enhance water removal in the flow channel. The experimental results indicated that the sub-channel design can decrease the pressure drop in the flow channel, and the sub-channels inlet positions (SIP, where the sub-channel inlets were placed along the cathode channel) and flow rates (SFR, percentage of air from the sub-channel inlet in the total cathode flow rate) had a considerable impact on water removal and cell performance. A proposed design that combines the SIP and SFR can effectively eliminate water from the fuel cell, increasing the maximum power density by more than 13.2% compared to the conventional design.

Removal of corallivorous snails as a proactive tool for the conservation of acroporid corals

PubMed Central

Miller, Margaret W.; Bright, Allan J.; Cameron, Caitlin M.

2014-01-01

Corallivorous snail feeding is a common source of tissue loss for the threatened coral, Acropora palmata, accounting for roughly one-quarter of tissue loss in monitored study plots over seven years. In contrast with larger threats such as bleaching, disease, or storms, corallivory by Coralliophila abbreviata is one of the few direct sources of partial mortality that may be locally managed. We conducted a field experiment to explore the effectiveness and feasibility of snail removal. Long-term monitoring plots on six reefs in the upper Florida Keys were assigned to one of three removal treatments: (1) removal from A. palmata only, (2) removal from all host coral species, or (3) no-removal controls. During the initial removal in June 2011, 436 snails were removed from twelve 150 m2 plots. Snails were removed three additional times during a seven month “removal phase”, then counted at five surveys over the next 19 months to track recolonization. At the conclusion, snails were collected, measured and sexed. Before-After-Control-Impact analysis revealed that both snail abundance and feeding scar prevalence were reduced in removal treatments compared to the control, but there was no difference between removal treatments. Recolonization by snails to baseline abundance is estimated to be 3.7 years and did not differ between removal treatments. Recolonization rate was significantly correlated with baseline snail abundance. Maximum snail size decreased from 47.0 mm to 34.6 mm in the removal treatments. The effort required to remove snails from A. palmata was 30 diver minutes per 150 m2 plot, compared with 51 min to remove snails from all host corals. Since there was no additional benefit observed with removing snails from all host species, removals can be more efficiently focused on only A. palmata colonies and in areas where C. abbreviata abundance is high, to effectively conserve A. palmata in targeted areas. PMID:25469321

Biological oxidation of hydrogen sulfide in mineral media using a biofilm airlift suspension reactor.

PubMed

Moghanloo, G M Mojarrad; Fatehifar, E; Saedy, S; Aghaeifar, Z; Abbasnezhad, H

2010-11-01

Hydrogen sulfide (H(2)S) removal in mineral media using Thiobacillus thioparus TK-1 in a biofilm airlift suspension reactor (BAS) was investigated to evaluate the relationship between biofilm formation and changes in inlet loading rates. Aqueous sodium sulfide was fed as the substrate into the continuous BAS-reactor. The reactor was operated at a constant temperature of 30 degrees C and a pH of 7, the optimal temperature and pH for biomass growth. The startup of the reactor was performed with basalt carrier material. Optimal treatment performance was obtained at a loading rate of 4.8 mol S(2-) m(-3) h(-1) at a conversion efficiency as high as 100%. The main product of H(2)S oxidation in the BAS-reactor was sulfate because of high oxygen concentrations in the airlift reactor. The maximum sulfide oxidation rate was 6.7 mol S(2-) m(-3) h(-1) at a hydraulic residence time of 3.3 h in the mineral medium. The data showed that the BAS-reactor with this microorganism can be used for sulfide removal from industrial effluent. Copyright 2010 Elsevier Ltd. All rights reserved.

[Bromate reduction by granular activated carbon].

PubMed

Huang, Xin; Gao, Nai-yun; Lu, Pin-pin

2007-10-01

Batch experiments were conducted to evaluate the kinetics of reducing bromate to bromide by granular activated carbon. Solution conditions were studied in details, such as pH, ionic strength, temperature and initial bromate concentration. The results showed the removal capacity of GAC was positively relevant to surface basic functional groups. The whole process was inhibited by other anions in solution and the inhibition sequence was NO3(-) > SO4(2-) > Cl(-). Pseudo-second order rate equation and intraparticle diffusion model were applied to fit the process of bromate reduction and the process of bromide formation, respectively, with regression coefficients higher than 0.97 at most cases. Bromate removal was found to be favored under conditions with low pH value and low ionic strength. Both sorption rate of bromate and formation rate of bromide were decreased, and then increased along with the increase of temperature during 15-42 degree C. In this experiment, the maximum adsorption capacity of GAC is 769.23 micromol/g (98.4 mg/g), whereas the sorption process is slow and easily influenced. It is concluded that the sorption of bromate by the micropore portion of GAC was influenced by the release of bromide.

A simple analytical method to estimate all exit parameters of a cross-flow air dehumidifier using liquid desiccant.

PubMed

Bassuoni, M M

2014-03-01

The dehumidifier is a key component in liquid desiccant air-conditioning systems. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the performance results of exit parameters from an analytical model of an adiabatic cross-flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. A program performing the analytical solution is developed using the engineering equation solver software. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and -5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration, and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier. The moisture removal rate is decreased with increasing both air inlet temperature and desiccant temperature while increases with increasing air to solution mass ratio, inlet desiccant concentration, and inlet air humidity ratio.

Operation of an anaerobic filter compared with an anaerobic moving bed bioreactor for the treatment of waste water from hydrothermal carbonisation of fine mulch.

PubMed

Meier, J F; Austermann-Haun, U; Fettig, J; Liebe, H; Wichern, M

2017-10-01

This experimental study investigates the anaerobic digestion of waste water from hydrothermal carbonisation of fine mulch (wood chips) in combination with a co-substrate for the first time. Two anaerobic reactors, an anaerobic filter (AF) and an anaerobic moving bed bioreactor (AnMBBR), were operated over a period of 131 days at mesophilic conditions. The organic loading rate was increased to a maximum of 8.5 g L -l d -1 in the AF and the AnMBBR. Both reactors achieved similarly efficient chemical oxygen demand removal rates of 80% approximately (approx.) and high methane production rates of approx. 2.7 L L -1 d -1 . Nevertheless, signs of an inhibition were observed during the experiments.

Feasibility study for the treatment of municipal wastewater by using a hybrid bio-solar process.

PubMed

Barwal, Anjali; Chaudhary, Rubina

2016-07-15

A moving bed biofilm reactor (MBBR) coupled with solar parabolic structured system has been designed and developed to get the maximum organic load removal and microbial disinfection from the wastewater. The effluent was first subjected to organic degradation in MBBR (with optimized carrier filling rate of 30%) followed by the bacterial degradation using solar energy in parabolic trough and the changes in values of parameters like pH, turbidity, chemical oxygen demand (COD), bio-chemical oxygen demand (BOD) and microbial count were monitored. The titanium dioxide (TiO2) was used as a photocatalyst for the removal of organic load from the wastewater but in optimized conditions. At optimum dose of 1.0 g/L of TiO2 and pH value of 7.6, maximum COD removal of 69% and 13% was achieved at sunny days (solar irradiation 400-700 W m(-2)) and cloudy days (solar irradiation 170-250 W m(-2)) respectively within 5-6 h solar irradiation time. The results obtained showed that it is possible to decrease in six logarithms (log) the concentration of TC and FC within only 240 min of solar exposure. Moreover, this process can offer economically reasonable, chemical free and practical solution to the processing of municipal wastewater where solar intensity is readily available and can be used for making zero liquid discharge (ZLD) an effective reality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Degradation of metaldehyde in water by nanoparticle catalysts and powdered activated carbon.

PubMed

Li, Zhuojun; Kim, Jong Kyu; Chaudhari, Vrushali; Mayadevi, Suseeladevi; Campos, Luiza C

2017-07-01

Metaldehyde, an organic pesticide widely used in the UK, has been detected in drinking water in the UK with a low concentration (<1 μg L -1 ) which is still above the European and UK standard requirements. This paper investigates the efficiency of four materials: powdered activated carbon (PAC) and carbon-doped titanium dioxide nanocatalyst with different concentrations of carbon (C-1.5, C-40, and C-80) for metaldehyde removal from aqueous solutions by adsorption and oxidation via photocatalysis. PAC was found to be the most effective material which showed almost over 90% removal. Adsorption data were well fitted to the Langmuir isotherm model, giving a q m (maximum/saturation adsorption capacity) value of 32.258 mg g -1 and a K L (Langmuir constant) value of 2.013 L mg -1 . In terms of kinetic study, adsorption of metaldehyde by PAC fitted well with a pseudo-second-order equation, giving the adsorption rate constant k 2 value of 0.023 g mg -1  min -1 , implying rapid adsorption. The nanocatalysts were much less effective in oxidising metaldehyde than PAC with the same metaldehyde concentration and 0.2 g L -1 loading concentration of materials under UV light; the maximum removal achieved by carbon-doped titanium dioxide (C-1.5) nanocatalyst was around 15% for a 7.5 ppm metaldehyde solution. Graphical abstract ᅟ.

Integrated horizontal-flow anaerobic and radial-flow aerobic reactors for the removal of organic matter and nitrogen from domestic sewage.

PubMed

Vieira, L G T; Fazolo, A; Zaiat, M; Foresti, E

2003-01-01

This paper presents the conception and discusses the results obtained from the operation of an integrated biological anaerobic/aerobic/anaerobic system composed of horizontal-flow anaerobic and radial-flow aerobic reactors for domestic sewage treatment. The performance of a horizontal-flow anaerobic immobilized biomass reactor, with five stages,followed by a radial-flow aerobic immobilized biomass reactor was evaluated along 22 weeks. After the 14th week, the last stage of the HAIB reactor was used as a denitrifying unit. Polyurethane foam cubic matrices with 1-cm sides were used as support for biomass immobilization in all the units. The influent domestic sewage presented mean chemical oxygen demand of 365 +/- 71 mg. 1(-1) and the temperature was 23 +/- 3degrees C. The integrated system achieved COD removal efficiency of 90% while the maximum ammonium removal efficiency was 97% in the aerobic post-treatment unit. The nitrification process was found to be better represented by first-order reactions in series model. The apparent first-order kinetic coefficient for nitrate formation was about 50 times higher than that estimated for the nitrite formation. The denitrification process was well represented by a Monod-type kinetic model. The maximum specific denitrifying rate and the half-saturation coefficient were 2.9 x 10(-4) mg NO(3)(-)-N mg(-1) VSS h(-1) and 19.4 mg NO(3)(-)-N 1(-1), respectively.

Long-term ammonia removal in a coconut fiber-packed biofilter: analysis of N fractionation and reactor performance under steady-state and transient conditions.

PubMed

Baquerizo, Guillermo; Maestre, Juan P; Machado, Vinicius C; Gamisans, Xavier; Gabriel, David

2009-05-01

A comprehensive study of long-term ammonia removal in a biofilter packed with coconut fiber is presented under both steady-state and transient conditions. Low and high ammonia loads were applied to the reactor by varying the inlet ammonia concentration from 90 to 260 ppm(v) and gas contact times ranging from 20 to 36 s. Gas samples and leachate measurements were periodically analyzed and used for characterizing biofilter performance in terms of removal efficiency (RE) and elimination capacity (EC). Also, N fractions in the leachate were quantified to both identify the experimental rates of nitritation and nitratation and to determine the N leachate distribution. Results showed stratification in the biofilter activity and, thus, most of the NH(3) removal was performed in the lower part of the reactor. An average EC of 0.5 kg N-NH(3)m(-3)d(-1) was obtained for the whole reactor with a maximum local average EC of 1.7 kg N-NH(3)m(-3)d(-1). Leachate analyses showed that a ratio of 1:1 of ammonium and nitrate ions in the leachate was obtained throughout steady-state operation at low ammonia loads with similar values for nitritation and nitratation rates. Low nitratation rates during high ammonia load periods occurred because large amounts of ammonium and nitrite accumulated in the packed bed, thus causing inhibition episodes on nitrite-oxidizing bacteria due to free ammonia accumulation. Mass balances showed that 50% of the ammonia fed to the reactor was oxidized to either nitrite or nitrate and the rest was recovered as ammonium indicating that sorption processes play a fundamental role in the treatment of ammonia by biofiltration.

Bio-energy generation in an affordable, single-chamber microbial fuel cell integrated with adsorption hybrid system: effects of temperature and comparison study.

PubMed

Tee, Pei-Fang; Abdullah, Mohammad Omar; Tan, Ivy A W; Amin, Mohamed A M; Nolasco-Hipolito, Cirilo; Bujang, Kopli

2018-04-01

A microbial fuel cell (MFC) integrated with adsorption system (MFC-AHS) is tested under various operating temperatures with palm oil mill effluent as the substrate. The optimum operating temperature for such system is found to be at ∼35°C with current, power density, internal resistance (R in ), Coulombic efficiency (CE) and maximum chemical oxygen demand (COD) removal of 2.51 ± 0.2 mA, 74 ± 6 mW m -3 , 25.4 Ω, 10.65 ± 0.5% and 93.57 ± 1.2%, respectively. Maximum current density increases linearly with temperature at a rate of 0.1772 mA m -2  °C -1 , whereas maximum power density was in a polynomial function. The temperature coefficient (Q 10 ) is found to be 1.20 between 15°C and 35°C. Present studies have demonstrated better CE performance when compared to other MFC-AHSs. Generally, MFC-AHS has demonstrated higher COD removals when compared to standalone MFC regardless of operating temperatures. ACFF: activated carbon fiber felt; APHA: American Public Health Association; CE: Coulombic efficiency; COD: chemical oxygen demand; ECG: electrocardiogram; GAC: granular activated carbon; GFB: graphite fiber brush; MFC: microbial fuel cell; MFC-AHS: microbial fuel cell integrated with adsorption hybrid system; MFC-GG: microbial fuel cell integrated with graphite granules; POME: palm oil mill effluent; PTFE: polytetrafluoroethylene; SEM: scanning electron microscope.

ARSENIC REMOVAL FROM DRINKING WATER BY IRON REMOVAL. USEPA DEMONSTRATION PROJECT AT CLIMAX, MN. PROJECT SUMMARY

EPA Science Inventory

This document is an eight page summary of the final report on arsenic demonstration project at Climax, MN (EPA/600/R-06/152). The objectives of the project are to evaluate the effectiveness of the Kinetico iron removal system in removing arsenic to meet the new arsenic maximum co...

Utilization of negative beat-frequencies for maximizing the update-rate of OFDR

NASA Astrophysics Data System (ADS)

Gabai, Haniel; Botsev, Yakov; Hahami, Meir; Eyal, Avishay

2015-07-01

In traditional OFDR systems, the backscattered profile of a sensing fiber is inefficiently duplicated to the negative band of spectrum. In this work, we present a new OFDR design and algorithm that remove this redundancy and make use of negative beat frequencies. In contrary to conventional OFDR designs, it facilitates efficient use of the available system bandwidth and enables distributed sensing with the maximum allowable interrogation update-rate for a given fiber length. To enable the reconstruction of negative beat frequencies an I/Q type receiver is used. In this receiver, both the in-phase (I) and quadrature (Q) components of the backscatter field are detected. Following detection, both components are digitally combined to produce a complex backscatter signal. Accordingly, due to its asymmetric nature, the produced spectrum will not be corrupted by the appearance of negative beat-frequencies. Here, via a comprehensive computer simulation, we show that in contrast to conventional OFDR systems, I/Q OFDR can be operated at maximum interrogation update-rate for a given fiber length. In addition, we experimentally demonstrate, for the first time, the ability of I/Q OFDR to utilize negative beat-frequencies for long-range distributed sensing.

Sewage treatment in integrated system of UASB reactor and duckweed pond and reuse for aquaculture.

PubMed

Mohapatra, D P; Ghangrekar, M M; Mitra, A; Brar, S K

2012-06-01

The performance of a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor and a duckweed pond containing Lemna gibba was investigated for suitability for treating effluent for use in aquaculture. While treating low-strength sewage having a chemical oxygen demand (COD) of typically less than 200 mg/L, with an increase in hydraulic retention time (HRT) from 10.04 to 33.49 h, COD removal efficiency of the UASB reactor decreased owing to a decrease in organic loading rate (OLR) causing poor mixing in the reactor. However, even at the lower OLR (0.475 kg COD/(m3 x d)), the UASB reactor gave a removal efficiency of 68% for COD and 74% for biochemical oxygen demand (BOD). The maximum COD, BOD, ammonia-nitrogen and phosphate removal efficiencies of the duckweed pond were 40.77%, 38.01%, 61.87% and 88.57%, respectively. Decreasing the OLR by increasing the HRT resulted in an increase in efficiency of the duckweed pond for removal of ammonia-nitrogen and phosphate. The OLR of 0.005 kg COD/(m2 x d) and HRT of 108 h in the duckweed pond satisfied aquaculture quality requirements. A specific growth rate of 0.23% was observed for tilapia fish fed with duckweed harvested from the duckweed pond. The economic analysis proved that it was beneficial to use the integrated system of a UASB reactor and a duckweed pond for treatment of sewage.

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

M. L. Abbott; K. N. Keck; R. E. Schindler

This screening level risk assessment evaluates potential adverse human health and ecological impacts resulting from continued operations of the calciner at the New Waste Calcining Facility (NWCF) at the Idaho Nuclear Technology and Engineering Center (INTEC), Idaho National Engineering and Environmental Laboratory (INEEL). The assessment was conducted in accordance with the Environmental Protection Agency (EPA) report, Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. This screening guidance is intended to give a conservative estimate of the potential risks to determine whether a more refined assessment is warranted. The NWCF uses a fluidized-bed combustor to solidifymore » (calcine) liquid radioactive mixed waste from the INTEC Tank Farm facility. Calciner off volatilized metal species, trace organic compounds, and low-levels of radionuclides. Conservative stack emission rates were calculated based on maximum waste solution feed samples, conservative assumptions for off gas partitioning of metals and organics, stack gas sampling for mercury, and conservative measurements of contaminant removal (decontamination factors) in the off gas treatment system. Stack emissions were modeled using the ISC3 air dispersion model to predict maximum particulate and vapor air concentrations and ground deposition rates. Results demonstrate that NWCF emissions calculated from best-available process knowledge would result in maximum onsite and offsite health and ecological impacts that are less then EPA-established criteria for operation of a combustion facility.« less

Efficient removal of Acid Green 25 dye from wastewater using activated Prunus Dulcis as biosorbent: Batch and column studies.

PubMed

Jain, Suyog N; Gogate, Parag R

2018-03-15

Biosorbent synthesized from dead leaves of Prunus Dulcis with chemical activation during the synthesis was applied for the removal of Acid Green 25 dye from wastewater. The obtained biosorbent was characterized using Brunauer-Emmett-Teller analysis, Fourier transform-infrared spectroscopy and scanning electron microscopy measurements. It was demonstrated that alkali treatment during the synthesis significantly increased surface area of biosorbent from 67.205 to 426.346 m 2 /g. The effect of various operating parameters on dye removal was investigated in batch operation and optimum values of parameters were established as pH of 2, 14 g/L as the dose of natural biosorbent and 6 g/L as the dose of alkali treated biosorbent. Relative error values were determined to check fitting of obtained data to the different kinetic and isotherm models. It was established that pseudo-second order kinetic model and Langmuir isotherm fitted suitably to the obtained batch experimental data. Maximum biosorption capacity values were estimated as 22.68 and 50.79 mg/g for natural biosorbent and for alkali activated Prunus Dulcis, respectively. Adsorption was observed as endothermic and activation energy of 6.22 kJ/mol confirmed physical type of adsorption. Column experiments were also conducted to probe the effectiveness of biosorbent for practical applications in continuous operation. Breakthrough parameters were established by studying the effect of biosorbent height, flow rate of dye solution and initial dye concentration on the extent of dye removal. The maximum biosorption capacity under optimized conditions in the column operation was estimated as 28.57 mg/g. Thomas and Yoon-Nelson models were found to be suitably fitted to obtained column data. Reusability study carried out in batch and continuous column operations confirmed that synthesized biosorbent can be used repeatedly for dye removal from wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Removal of p-xylene from an air stream in a hybrid biofilter.

PubMed

Wu, Dan; Quan, Xie; Zhao, Yazhi; Chen, Shuo

2006-08-21

Biofiltration of an air stream containing p-xylene has been studied in a laboratory hybrid biofilter packed with a mixture of mature pig compost, forest soil and the packing material which was made of polyethylene (PE) and used in the moving bed biological reactor (MBBR) in wastewater treatment. Three flow rates, 9.17, 19.87 and 40.66 m(3)m(-2)h(-1), were investigated for p-xylene inlet concentration ranging from 0.1 to 3.3 g m(-3). A high elimination capacity of 80 g m(-3)h(-1) corresponding to removal efficiency of 96% was obtained at a flow rate of 9.17 m(3)m(-2)h(-1) (empty bed residence time of 132 s). At a flow rate of 40.66 m(3)m(-2)h(-1) (empty bed residence time of 30s), the maximum elimination capacity for p-xylene was 40 g m(-3)h(-1) and removal efficiencies were in the range of 47-100%. The production of carbon dioxide (P(CO(2))) is proportional to elimination capacity (EC) and the linear relation was formulated as P(CO(2))=1.65EC+15.58. Stable pH values ranging from 6.3 to 7.6 and low pressure drop values less than 0.2 cm H(2)O (19.6 Pa) of packing media in compost-based biofilter of hybrid biofilter were observed, which avoided acidification and compaction of packing media and sustained the activity of microorganism populations.

Underestimated effects of sediments on enhanced startup performance of biofilm systems for polluted source water pretreatment.

PubMed

Lv, Zheng-Hui; Wang, Jing; Yang, Guang-Feng; Feng, Li-Juan; Mu, Jun; Zhu, Liang; Xu, Xiang-Yang

2018-02-01

In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH 4 + -N removal rate of 0.35 mg L -1 h -1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH 4 + -N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at  phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.

Adsorbent for p-phenylenediamine adsorption and removal based on graphene oxide functionalized with magnetic cyclodextrin

NASA Astrophysics Data System (ADS)

Wang, Dongxue; Liu, Liangliang; Jiang, Xinyu; Yu, Jingang; Chen, Xiaohong; Chen, Xiaoqing

2015-02-01

Recently, graphene oxide (GO) based magnetic nanocomposites have been widely used in an adsorption-based process for the removal of organic pollutants from the water system. In this study, magnetic β-cyclodextrin-graphene oxide nanocomposites (MCG) were synthesized according to covalent binding of magnetic β-cyclodextrin nanoparticles onto the GO surface and the as-made nanocomposites were successfully applied as adsorbents for the adsorption and removal of p-phenylenediamines (PPD). The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Effects of pH, temperature, time and reusability on the adsorption of PPD were investigated, as well as the kinetics and isotherms parameters of the adsorbents were determined. The results indicated that the maximum adsorption capacity of MCG was 1102.58 mg/g at 45 °C and pH 8. The adsorption capacity remained at 81% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with PPD was found that fitted pseudo-second-order kinetics equations and the Langmuir adsorption model. The results showed the MCG had a good adsorption ability to remove organic pollutants in wastewater.

The potential premium range of risk-rating in competitive markets for supplementary health insurance.

PubMed

Paolucci, Francesco; Prinsze, Femmeke; Stam, Pieter J A; van de Ven, Wynand P M M

2009-09-01

In this paper, we simulate several scenarios of the potential premium range for voluntary (supplementary) health insurance, covering benefits which might be excluded from mandatory health insurance (MI). Our findings show that, by adding risk-factors, the minimum premium decreases and the maximum increases. The magnitude of the premium range is especially substantial for benefits such as medical devices and drugs. When removing benefits from MI policymakers should be aware of the implications for the potential reduction of affordability of voluntary health insurance coverage in a competitive market.

A fast acting electrical servo for the actuation of full span, Fowler-type wing flaps in DLC applications: A detail design study

NASA Technical Reports Server (NTRS)

Smetana, F. O.; Montoya, R. J.; Carden, R. K.

1972-01-01

The philosophy and detail design of an electro-mechanical actuator for Fowler-type wing flaps which have a response time constant of 0.025 seconds are described. A conventional electrical servomotor with a power rating twice the maximum power delivered to the load is employed along with adaptive, gain-scheduled feedback and various logic circuits, including one to remove electrical excitation from the motor during extended periods when no motion of the flap is desired.

Production of biogenic manganese oxides coupled with methane oxidation in a bioreactor for removing metals from wastewater.

PubMed

Matsushita, Shuji; Komizo, Daisuke; Cao, Linh Thi Thuy; Aoi, Yoshiteru; Kindaichi, Tomonori; Ozaki, Noriatsu; Imachi, Hiroyuki; Ohashi, Akiyoshi

2018-03-01

Biogenic manganese oxide (BioMnO x ) can efficiently adsorb various minor metals. The production of BioMnO x in reactors to remove metals during wastewater treatment processes is a promising biotechnological method. However, it is difficult to preferentially enrich manganese-oxidizing bacteria (MnOB) to produce BioMnO x during wastewater treatment processes. A unique method of cultivating MnOB using methane-oxidizing bacteria (MOB) to produce soluble microbial products is proposed here. MnOB were successfully enriched in a methane-fed reactor containing MOB. BioMnO x production during the wastewater treatment process was confirmed. Long-term continual operation of the reactor allowed simultaneous removal of Mn(II), Co(II), and Ni(II). The Co(II)/Mn(II) and Ni(II)/Mn(II) removal ratios were 53% and 19%, respectively. The degree to which Mn(II) was removed indicated that the enriched MnOB used utilization-associated products and/or biomass-associated products. Microbial community analysis revealed that methanol-oxidizing bacteria belonging to the Hyphomicrobiaceae family played important roles in the oxidation of Mn(II) by using utilization-associated products. Methane-oxidizing bacteria were found to be inhibited by MnO 2 , but the maximum Mn(II) removal rate was 0.49 kg m -3  d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Synergistic effects and optimization of nitrogen and phosphorus concentrations on the growth and nutrient uptake of a freshwater Chlorella vulgaris.

PubMed

Alketife, Ahmed M; Judd, Simon; Znad, Hussein

2017-01-01

The synergistic effects and optimization of nitrogen (N) and phosphorus (P) concentrations on the growth of Chlorella vulgaris (CCAP 211/11B, CS-42) and nutrient removal have been investigated under different concentrations of N (0-56 mg/L) and P (0-19 mg/L). The study showed that N/P ratio has a crucial effect on the biomass growth and nutrient removal. When N/P=10, a complete P and N removal was achieved at the end of cultivation with specific growth rate (SGR) of 1 d -1 and biomass concentration of 1.58 g/L. It was also observed that when the N content <2.5 mg/L, the SGR significantly reduced from 1.04 to 0.23 d -1 and the maximum biomass produced was decreased more than three-fold to 0.5 g/L. The Box-Behnken experimental design and response surface method were used to study the effects of the initial concentrations (P, N and C) on P and N removal efficiencies. The optimized P, N and C concentrations supporting 100% removal of both P and N at an SGR of 0.95 were 7, 55 and 10 mg/L respectively, with desirability value of 0.94. The results and analysis obtained could be very useful when applying the microalgae for efficient wastewater treatment and nutrient removal.

Nitrogen removal and mass balance in newly-formed Myriophyllum aquaticum mesocosm during a single 28-day incubation with swine wastewater treatment.

PubMed

Liu, Feng; Zhang, Shunan; Wang, Yi; Li, Yong; Xiao, Runlin; Li, Hongfang; He, Yang; Zhang, Miaomiao; Wang, Di; Li, Xi; Wu, Jinshui

2016-01-15

The aim of this research was to assess the applicability of Myriophyllum (M.) aquaticum for swine wastewater treatment. Nitrogen (N) removal processes were investigated in M. aquaticum mesocosms with swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two strengths of synthetic wastewater, 200 mg [Formula: see text] L(-1) (200 [Formula: see text] ) and 400 mg [Formula: see text] L(-1) (400 [Formula: see text] ). During a 28-day incubation period, the average [Formula: see text] and TN removal rates were 99.8% and 94.2% for 50% SW and 99.8% and 93.8% for SW, which were greater than 86.5% and 83.7% for 200 [Formula: see text] , and 73.7% and 74.1% for 400 [Formula: see text] , respectively. A maximum areal total nitrogen (TN) removal rate of 157.8 mg N m(-2) d(-1) was found in M. aquaticum mesocosms with SW. During the incubation period, the observed dynamics of [Formula: see text] concentrations in water and gene copy numbers of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), nirK and nirS in soil unraveled strong nitrification and denitrification processes occurring in M. aquaticum mesocosms with swine wastewater. The N mass balance analysis indicated that plant uptake and soil N accumulation accounted for 17.9-42.2% and 18.0-43.8% of the initial TN load, respectively. The coupled nitrification and denitrification process was calculated to account for, on average, 36.8% and 62.8% of TN removal for 50% SW and SW, respectively. These findings demonstrated that the N uptake by M. aquaticum contributed to a considerable proportion of N removal. In particular, the activities of ammonia-oxidizing and denitrification microbes responsible for nitrification and denitrification processes in M. aquaticum mesocosm accelerated [Formula: see text] and TN removal from swine wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of climatic conditions, season and wastewater quality on contaminant removal efficiency of two experimental constructed wetlands in different regions of Spain.

PubMed

Garfí, Marianna; Pedescoll, Anna; Bécares, Eloy; Hijosa-Valsero, María; Sidrach-Cardona, Ricardo; García, Joan

2012-10-15

The aim of this study was to examine the effects of climate, season and wastewater quality on contaminant removal efficiency of constructed wetlands implemented in Mediterranean and continental-Mediterranean climate region of Spain. To this end, two experimental horizontal subsurface flow constructed wetlands located in Barcelona and León (Spain) were compared. The two constructed wetland systems had the same experimental set-up. Each wetland had a surface area of 2.95 m(2), a water depth of 25 cm and a granular medium of D(60)=7.3 mm, and was planted with Phragmites australis. Both systems were designed in order to operate with a maximum organic loading rate of 6 g(DBO) m(-2) d(-1). Experimental systems operated with a hydraulic loading rate of 28.5 and 98 mm d(-1) in Barcelona and León, respectively. Total suspended solids, biochemical oxygen demand and ammonium mass removal efficiencies followed seasonal trends, with higher values in the summer (97.4% vs. 97.8%; 97.1% vs. 96.2%; 99.9% vs. 88.9%, in Barcelona and León systems, respectively) than in the winter (83.5% vs. 74.4%; 73.2% vs. 60.6%; 19% vs. no net removal for ammonium in Barcelona and León systems, respectively). During the cold season, biochemical oxygen demand and ammonium removal were significantly higher in Barcelona system than in León, as a result of higher temperature and redox potential in Barcelona. During the warm season, statistical differences were observed only for ammonium removal. Results showed that horizontal subsurface flow constructed wetland is a successful technology for both regions considered, even if winter seemed to be a critical period for ammonium removal in continental climate regions. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of biogas flow rate on biomass composition during the optimization of biogas upgrading in microalgal-bacterial processes.

PubMed

Serejo, Mayara L; Posadas, Esther; Boncz, Marc A; Blanco, Saúl; García-Encina, Pedro; Muñoz, Raúl

2015-03-03

The influence of biogas flow rate (0, 0.3, 0.6, and 1.2 m(3) m(-2) h(-1)) on the elemental and macromolecular composition of the algal-bacterial biomass produced from biogas upgrading in a 180 L photobioreactor interconnected to a 2.5 L external bubbled absorption column was investigated using diluted anaerobically digested vinasse as cultivation medium. The influence of the external liquid recirculation/biogas ratio (0.5 < L/G < 67) on the removal of CO2 and H2S, and on the concentrations of O2 and N2 in the upgraded biogas, was also evaluated. A L/G ratio of 10 was considered optimum to support CO2 and H2S removals of 80% and 100%, respectively, at all biogas flow rates tested. Biomass productivity increased at increasing biogas flow rate, with a maximum of 12 ± 1 g m(-2) d(-1) at 1.2 m(3) m(-2) h(-1), while the C, N, and P biomass content remained constant at 49 ± 2%, 9 ± 0%, and 1 ± 0%, respectively, over the 175 days of experimentation. The high carbohydrate contents (60-76%), inversely correlated to biogas flow rates, would allow the production of ≈100 L of ethanol per 1000 m(3) of biogas upgraded under a biorefinery process approach.

Polar drug residues in sewage and natural waters in the state of Rio de Janeiro, Brazil.

PubMed

Stumpf, M; Ternes, T A; Wilken, R D; Rodrigues, S V; Baumann, W

1999-01-12

The drug residues of lipid regulators, anti-inflammatories and some drug metabolites have been detected in raw sewage, treated waste water and river water in the state of Rio de Janeiro, Brazil. These residues are mainly derived from humans via excretion. The median concentrations in the effluents of sewage treatment plants (STPs) of most drugs investigated in this study ranged from 0.1 to 1 microgram/l. The removal rates of individual drugs during passage through a Brazilian STP varied from 12 to 90%. As a consequence of the incomplete removal of these residues during passage through a STP, rivers were also found to be contaminated. Median concentrations ranged from between 0.02 and 0.04 microgram/l in river water, whereas the maximum values were observed to be up to 0.5 microgram/l.

Anaerobic digestion of glycerol and co-digestion of glycerol and pig manure.

PubMed

Nuchdang, Sasikarn; Phalakornkule, Chantaraporn

2012-06-30

The potential of glycerol obtained from transesterification of waste cooking oil as a main carbon source for biogas production was investigated. The glycerol was highly contaminated with oils and fats and was pretreated with sulfuric acid. Using a carbon source of glucose as a control, we compared biogas production from the acid-treated glycerol in a synthetic medium and the acid-treated glycerol mixed with pig manure. The anaerobic digestion of acid-treated glycerol with supplement in a synthetic medium was found to be satisfactory at organic loading rates (OLR) between 1.3, 1.6 and 2.6 g chemical oxygen demand (COD) L(-1) d(-1). The maximum methane yield of 0.32 L at Standard temperature and pressure (STP) g(-1) COD removal was achieved at an OLR of 1.6 g COD L(-1) d(-1) and the methane content was 54% on an average. At a higher organic loading rate of 5.4 g COD L(-1) d(-1), the propionic acid to acetic acid ratio was higher than the critical threshold limit for metabolic imbalance. Anaerobic digestion of acid-treated glycerol with pig manure was also investigated at the COD ratio of 80:20 (glycerol:pig manure). The anaerobic digestion of acid-treated glycerol with pig manure was found to be satisfactory at organic loading rates between 1.3, 1.7, 2.9 and 5.0 g COD L(-1) d(-1) in terms of COD reduction (>80%) and methane content of (62% on an average). However, the biogas production rate was found to significantly decrease at the highest load. The maximum methane yield of 0.24 L STP g(-1) COD removal was achieved at an OLR of 1.3 g COD L(-1) d(-1). Copyright © 2012 Elsevier Ltd. All rights reserved.

Biodegradation of 3,5-dimethyl-2,4-dichlorophenol in saline wastewater by newly isolated Penicillium sp. yz11-22N2.

PubMed

Yan, Zhou; He, Huijun; Yang, Chunping; Zeng, Guangming; Luo, Le; Jiao, Panpan; Li, Huiru; Lu, Li

2017-07-01

In this study, the performance of 3,5-dimethyl-2,4-dichlorophenol (DCMX) degradation by a screened strain was investigated. 18S rDNA and the neighbor-joining method were used for identification of the isolated strain. The results of phylogenetic analysis and scanning electron micrographs showed that the most probable identity of the screened strain should be Penicillium sp. Growth characteristics of Penicillium sp. and degradation processes of DCMX were examined. Fourier transform infrared spectroscopy of the inoculated DCMX solution was recorded, which supported the capacity of DCMX degradation by the screened Penicillium sp. Under different salinity conditions, the highest growth rate and removal efficiency for DCMX were obtained at pH6.0. The removal efficiency decreased from 100% to 66% when the DCMX concentration increased from 5 to 60mg/L, respectively. Using a Box-Behnken design, the maximum DCMX removal efficiency was determined to be 98.4%. With acclimation to salinity, higher removal efficiency could be achieved. The results demonstrate that the screened Penicillium sp. has the capability for degradation of DCMX. Copyright © 2017. Published by Elsevier B.V.

One-step synthesis of water-dispersible cysteine functionalized magnetic Fe3O4 nanoparticles for mercury(II) removal from aqueous solutions

NASA Astrophysics Data System (ADS)

Shen, Xiaofang; Wang, Qin; Chen, WenLing; Pang, Yuehong

2014-10-01

Cysteine functionalized Fe3O4 magnetic nanoparticles (Cys-Fe3O4 MNPs) were prepared facilely for Hg(II) removal from aqueous solutions. Using Fe2+ as precursors, air as oxidant and Cys as protectant, this novel material was one-pot synthesis at room temperature by oxidation-precipitation method with the assistance of sonication. The MNPs were characterized by TEM, VSM, FTIR, X-ray powder diffraction analysis (XRD) and TGA methods. Under the optimum experimental conditions, the removal efficiency was as high as 95% and the maximum sorption capacity is found to be 380 mg/mol for Hg(II). Study on adsorption kinetics shows that adsorption of Hg(II) onto Cys-Fe3O4 MNPs follows pseudo-first-order kinetic model and the adsorption rate constant was 0.22 min-1. Additionally, the Hg(II)-loaded Cys-Fe3O4 MNPs could be easily regenerated up to 95% using 1.0 M acetic acid. These results indicated that Cys-Fe3O4 MNPs is a potentially attractive material for the removal of Hg(II) from water.

Effects of substrate concentrations on the growth of heterotrophic bacteria and algae in secondary facultative ponds.

PubMed

Kayombo, S; Mbwette, T S A; Katima, J H Y; Jorgensen, S E

2003-07-01

This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of batch chemostat reactors. From the laboratory data, the specific growth rate (micro) was determined using the modified Gompertz model. The maximum specific growth rate ( micro(max)) and half saturation coefficients (K(s)) were calculated using the Monod kinetic equation. The maximum observed growth rate ( micro(max)) for heterotrophic bacteria was 3.8 day(-1) with K(s) of 200 mg COD/l. The micro(max) for algal biomass based on suspended volatile solids was 2.7 day(-1) with K(s) of 110 mg COD/l. The micro(max) of algae based on the chlorophyll-a was 3.5 day(-1) at K(s) of 50mg COD/l. The observed specific substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of SFPs.

[Changes of masseter muscle asymmetry due to unilateral mastication after intervention: a electromyographic analysis].

PubMed

Wang, Yun; Teng, Chen; Wang, Meng-Ya

2015-04-01

To explore the effect of intervention with unilateral mastication on masseter muscle asymmetry. Forty-three subjects (19 males and 24 females, mean age 20.0∓0.5 years) with unilateral chewing were divided into group A0 with motivation and without intervention, group A1 with motivation and intervention, group B0 without motivation or intervention, and group B1 without motivation but with intervention. In groups A0 and A1, the motivation was removed and groups A1 and group B1 received interventions. Surface electromyography was recorded using surface electromyography in all the subjects in mandible postural position (MPP), with maximum clenching in intercuspal position (ICP) and during chewing. The sEMG of the left and right masseter muscle were separately recorded to assess the asymmetry index of the masseter muscles (ASMM) and its changes after intervention. In groupA0, the ASMM at MPP, during maximum clenching and chewing had no obvious changes after removal of the motivation. In group A1, the ASMM at MPP, during maximum clenching and chewing were obviously decreased after intervention. In group B0, the ASMM at MPP and during maximum clenching showed no obvious changes but ASMM during chewing significantly increased after removal of the motivation. In group B1, the ASMM at MPP, during maximum clenching and chewing all decreased obviously after intervention. Interventions can significantly improve the bilateral symmetry of the masseter muscles in subjects with unilateral chewing, and the motivation for unilateral chewing should be removed before intervention.

Nitric oxide for anammox recovery in a nitrite-inhibited deammonification system.

PubMed

Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Loorits, Liis; Kroon, Kristel; Fritze, Hannu; Tuomivirta, Tero; Vabamäe, Priit; Raudkivi, Markus; Mandel, Anni; Dc Rubin, Sergio S C; Tenno, Taavo

2015-01-01

The anaerobic ammonium oxidation (anammox) process is widely used for N-rich wastewater treatment. In the current research the deammonification reactor in a reverse order (first anammox, then the nitrifying biofilm cultivation) was started up with a high maximum N removal rate (1.4 g N m(-2) d(-1)) in a moving bed biofilm reactor. Cultivated biofilm total nitrogen removal rates were accelerated the most by anammox intermediate - nitric oxide (optimum 58 mg NO-N L(-1)) addition. Furthermore, NO was added in order to eliminate inhibition caused by nitrite concentrations (>50 mg [Formula: see text]) increasing [Formula: see text] (2/1, respectively) along with a higher ratio of [Formula: see text] (0.6/1, respectively) than stoichiometrical for this optimal NO amount added during batch tests. Planctomycetales clone P4 sequences, which was the closest (98% and 99% similarity, respectively) relative to Candidatus Brocadia fulgida sequences quantities increase to 1 × 10(6) anammox gene copies g(-1) total suspended solids to till day 650 were determined by quantitative polymerase chain reaction.

Integrated hydrogen production process from cellulose by combining dark fermentation, microbial fuel cells, and a microbial electrolysis cell.

PubMed

Wang, Aijie; Sun, Dan; Cao, Guangli; Wang, Haoyu; Ren, Nanqi; Wu, Wei-Min; Logan, Bruce E

2011-03-01

Hydrogen gas production from cellulose was investigated using an integrated hydrogen production process consisting of a dark fermentation reactor and microbial fuel cells (MFCs) as power sources for a microbial electrolysis cell (MEC). Two MFCs (each 25 mL) connected in series to an MEC (72 mL) produced a maximum of 0.43 V using fermentation effluent as a feed, achieving a hydrogen production rate from the MEC of 0.48 m(3) H(2)/m(3)/d (based on the MEC volume), and a yield of 33.2 mmol H(2)/g COD removed in the MEC. The overall hydrogen production for the integrated system (fermentation, MFC and MEC) was increased by 41% compared with fermentation alone to 14.3 mmol H(2)/g cellulose, with a total hydrogen production rate of 0.24 m(3) H(2)/m(3)/d and an overall energy recovery efficiency of 23% (based on cellulose removed) without the need for any external electrical energy input. Copyright © 2010 Elsevier Ltd. All rights reserved.

Lead recovery from waste CRT funnel glass by high-temperature melting process.

PubMed

Hu, Biao; Hui, Wenlong

2018-02-05

In this research, a novel and effective process for waste CRT funnel glass treatment was developed. The key to this process is removal of lead from the CRT funnel glass by high-temperature melting process. Sodium carbonate powder was used as a fusion agent, sodium sulfide serves as a catalytic agent and carbon powder acts as reducing agent. Experimental results showed that lead recovery rate increased with an increase in the amount of added sodium carbonate, sodium sulfide, carbonate, temperature and holding time initially, and then reached a stable value. The maximum lead recovery rate was approximately 94%, when the optimum adding amount of sodium carbonate, sodium sulfide, carbonate, temperature and holding time were 25%, 8%, 3.6%, 1200°C and 120min, respectively. In the high-temperature melting process, lead silicate in the funnel glass was firstly reduced, and then removed. The glass slag can be made into sodium and potassium silicate by hydrolysis process. This study proposed a practical and economical process for recovery of lead and utilization of waste glass slag. Copyright © 2017 Elsevier B.V. All rights reserved.

Cometabolic degradation of chloramphenicol via a meta-cleavage pathway in a microbial fuel cell and its microbial community.

PubMed

Zhang, Qinghua; Zhang, Yanyan; Li, Daping

2017-04-01

The performance of a microbial fuel cell (MFC) in terms of degradation of chloramphenicol (CAP) was investigated. Approximately 84% of 50mg/L CAP was degraded within 12h in the MFC. A significant interaction of pH, temperature, and initial CAP concentration was found on removal of CAP, and a maximum degradation rate of 96.53% could theoretically be achieved at 31.48°C, a pH of 7.12, and an initial CAP concentration of 106.37mg/L. Moreover, CAP was further degraded through a ring-cleavage pathway. The antibacterial activity of CAP towards Escherichia coli ATCC 25922 and Shewanella oneidensis MR-1 was largely eliminated by MFC treatment. High-throughput sequencing analysis indicated that Azonexus, Comamonas, Nitrososphaera, Chryseobacterium, Azoarcus, Rhodococcus, and Dysgonomonas were the predominant genera in the MFC anode biofilm. In conclusion, the MFC shows potential for the treatment of antibiotic residue-containing wastewater due to its high rates of CAP removal and energy recovery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous biogas upgrading and centrate treatment in an outdoors pilot scale high rate algal pond.

PubMed

Posadas, Esther; Marín, David; Blanco, Saúl; Lebrero, Raquel; Muñoz, Raúl

2017-05-01

The bioconversion of biogas to biomethane coupled to centrate treatment was evaluated in an outdoors pilot scale high rate algal pond interconnected to an external CO 2 -H 2 S absorption column (AC) via settled broth recirculation. CO 2 -removal efficiencies ranged from 50 to 95% depending on the alkalinity of the cultivation broth and environmental conditions, while a complete H 2 S removal was achieved regardless of the operational conditions. A maximum CH 4 concentration of 94% with a limited O 2 and N 2 stripping was recorded in the upgraded biogas at recycling liquid/biogas ratios in the AC of 1 and 2. Process operation at a constant biomass productivity of 15gm -2 d -1 and the minimization of effluent generation supported high carbon and nutrient recoveries in the harvested biomass (C=66±8%, N=54±18%, P≈100% and S=16±3%). Finally, a low diversity in the structure of the microalgae population was promoted by the environmental and operational conditions imposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Groundwater depletion in the United States (1900−2008)

USGS Publications Warehouse

Konikow, Leonard F.

2013-01-01

A natural consequence of groundwater withdrawals is the removal of water from subsurface storage, but the overall rates and magnitude of groundwater depletion in the United States are not well characterized. This study evaluates long-term cumulative depletion volumes in 40 separate aquifers or areas and one land use category in the United States, bringing together information from the literature and from new analyses. Depletion is directly calculated using calibrated groundwater models, analytical approaches, or volumetric budget analyses for multiple aquifer systems. Estimated groundwater depletion in the United States during 1900–2008 totals approximately 1,000 cubic kilometers (km3). Furthermore, the rate of groundwater depletion has increased markedly since about 1950, with maximum rates occurring during the most recent period (2000–2008) when the depletion rate averaged almost 25 km3 per year (compared to 9.2 km3 per year averaged over the 1900–2008 timeframe).

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.

Fermentative hydrogen production from molasses wastewater in a continuous mixed immobilized sludge reactor.

PubMed

Han, Wei; Wang, Bing; Zhou, Yan; Wang, De-Xin; Wang, Yan; Yue, Li-Ran; Li, Yong-Feng; Ren, Nan-Qi

2012-04-01

A novel continuous mixed immobilized sludge reactor (CMISR) containing activated carbon as support carrier was used for fermentative hydrogen production from molasses wastewater. When the CMISR system operated at the conditions of influent COD of 2000-6000mg/L, hydraulic retention time (HRT) of 6h and temperature of 35°C, stable ethanol type fermentation was formed after 40days operation. The H(2) content in biogas and chemical oxygen demand (COD) removal were estimated to be 46.6% and 13%, respectively. The effects of organic loading rates (OLRs) on the CMISR hydrogen production system were also investigated. It was found that the maximum hydrogen production rate of 12.51mmol/hL was obtained at OLR of 32kg/m(3)d and the maximum hydrogen yield by substrate consumed of 130.57mmol/mol happened at OLR of 16kg/m(3)d. Therefore, the continuous mixed immobilized sludge reactor (CMISR) could be a promising immobilized system for fermentative hydrogen production. Copyright © 2012 Elsevier Ltd. All rights reserved.

Principles and applications of laser-induced liquid-phase jet-chemical etching

NASA Astrophysics Data System (ADS)

Stephen, Andreas; Metev, Simeon; Vollertsen, Frank

2003-11-01

In this treatment method laser radiation, which is guided from a coaxially expanding liquid jet-stream, locally initiates a thermochemical etching reaction on a metal surface, which leads to selective material removal at high resolution and quality of the treated surface as well as low thermal influence on the workpiece. Electrochemical investigations were performed under focused laser irradiation using a cw-Nd:YAG laser with a maximum power of 15 W and a simultaneous impact of the liquid jet-stream consisting of phosphoric acid with a maximum flow rate of 20 m/s. The time resolved measurements of the electrical potential difference against an electrochemical reference electrode were correlated with the specific processing parameters and corresponding etch rates to identify processing conditions for temporally stable and enhanced chemical etching reactions. Applications of laser-induced liquid-phase jet-chemical etching in the field of sensor technology, micromechanics and micrmoulding technology are presented. This includes the microstructuring of thin film systems, cutting of foils of shape memory alloys or the generation of structures with defined shape in bulk material.

Optimization of operating parameters for gas-phase photocatalytic splitting of H2S by novel vermiculate packed tubular reactor.

PubMed

Preethi, V; Kanmani, S

2016-10-01

Hydrogen production by gas-phase photocatalytic splitting of Hydrogen Sulphide (H2S) was investigated on four semiconductor photocatalysts including CuGa1.6Fe0.4O2, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2. The CdS and ZnS coated core shell particles (CdS + ZnS)/Fe2O3 shows the highest rate of hydrogen (H2) production under optimized conditions. Packed bed tubular reactor was used to study the performance of prepared photocatalysts. Selection of the best packing material is a key for maximum removal efficiency. Cheap, lightweight and easily adsorbing vermiculate materials were used as a novel packing material and were found to be effective in splitting H2S. Effect of various operating parameters like flow rate, sulphide concentration, catalyst dosage, light irradiation were tested and optimized for maximum H2 conversion of 92% from industrial waste H2S. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-speed photography of plasma during excimer laser-tissue interaction.

PubMed

Murray, Andrea K; Dickinson, Mark R

2004-08-07

During high fluence laser-tissue interaction, ablation of tissue occurs, debris is removed from the ablation site and is then ejected at high velocity. This debris may be observed as a combination of luminous plasma and non-luminous plume, both of which have the potential to shield the ablation site. This study examined the role of ablation debris in shielding the tissue and determined its effects on the ablation rate over a range of laser pulse energies, pulse repetition rates and pulse numbers for dentine; the velocity differences between hard and soft tissues were also examined. High-speed photography was carried out at up to 1 x 10(8) frames per second. A maximum velocity of 2.58 +/- 0.52 x 10(4) m s(-1) was recorded for dentine debris within the first 10 ns following ejection. The maximum duration of tissue shielding due to a single pulse, determined by attenuation of a probe beam, was found to be approximately 7 ms, approximately 80 micros of which was due to luminous plasma and the remainder due to the non-luminous plume.

Application of gas cyclone-liquid jet absorption separator for purification of tail gas containing ammonia.

PubMed

Ma, Liang; Zhao, Zhi-Huang; Peng, Lv; Yang, Xue-Jing; Fu, Peng-Bo; Liu, Yi; Huang, Yuan

2018-05-31

In this experiment, with stainless steel gas cyclone-liquid jet absorption separator as carrier, NH 3 as experimental gas, and water and H 3 PO 4 solution as absorbents, corresponding NH 3 absorption rate change is obtained through the adjustment of experimental parameters, such as NH 3 inlet concentration, inlet velocity of mixed gas, injection flow rate of absorbent, temperature of absorbent, and H 3 PO 4 absorbent concentration. The NH 3 absorption rate decreases with the increase in NH 3 inlet concentration and inlet gas velocity. The NH 3 absorption rate will increase first and then tends to remain unchanged after reaching a certain degree with the increase in liquid injection flow rate and absorbent concentration. The NH 3 absorption rate will increase first and then decrease with the increase in the absorbent temperature. The maximum NH 3 removal efficiencies of water and H 3 PO 4 were 96% and 99%, respectively.

Computation of adsorption parameters for the removal of dye from wastewater by microwave assisted sawdust: Theoretical and experimental analysis.

PubMed

S, Suganya; P, Senthil Kumar; A, Saravanan; P, Sundar Rajan; C, Ravikumar

2017-03-01

In this research, the microwave assistance has been employed for the preparation of novel material from agro/natural bio-waste i.e. sawdust, for the effective removal of methylene blue (MB) dye from aqueous solution. The characterization of the newly prepared microwave assisted sawdust (MASD) material was performed by using FTIR, SEM and XRD analyses. In order to obtain the maximum removal of MB dye from wastewater, the adsorption experimental parameters such as initial dye concentration, contact time, solution pH and adsorbent dosage were optimized by trial and error approach. The obtained experimental results were applied to the different theoretical models to predict the system behaviour. The optimum conditions for the maximum removal MB dye from aqueous solution for an initial MB dye concentration of 25mg/L was calculated as: adsorbent dose of 3g/L, contact time of 90min, solution pH of 7.0 and at the temperature of 30°C. Freundlich and pseudo-second order models was best obeyed with the studied experimental data. Langmuir maximum monolayer adsorption capacity of MASD for MB dye removal was calculated as 58.14mg of MB dye/g of MASD. Adsorption diffusion model stated that the present adsorption system was controlled by intraparticle diffusion model. The obtained results proposed that, novel MASD was considered to be an effective and low-cost adsorbent material for the removal of dye from wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

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%.

Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

NASA Technical Reports Server (NTRS)

Abraham, Martin; Fisher, John W.

1995-01-01

The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst, prepared at The University of Tulsa, at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

High rate manure supernatant digestion.

PubMed

Bergland, Wenche Hennie; Dinamarca, Carlos; Toradzadegan, Mehrdad; Nordgård, Anna Synnøve Røstad; Bakke, Ingrid; Bakke, Rune

2015-06-01

The study shows that high rate anaerobic digestion may be an efficient way to obtain sustainable energy recovery from slurries such as pig manure. High process capacity and robustness to 5% daily load increases are observed in the 370 mL sludge bed AD reactors investigated. The supernatant from partly settled, stored pig manure was fed at rates giving hydraulic retention times, HRT, gradually decreased from 42 to 1.7 h imposing a maximum organic load of 400 g COD L(-1) reactor d(-1). The reactors reached a biogas production rate of 97 g COD L(-1) reactor d(-1) at the highest load at which process stress signs were apparent. The yield was ∼0.47 g COD methane g(-1) CODT feed at HRT above 17 h, gradually decreasing to 0.24 at the lowest HRT (0.166 NL CH4 g(-1) CODT feed decreasing to 0.086). Reactor pH was innately stable at 8.0 ± 0.1 at all HRTs with alkalinity between 9 and 11 g L(-1). The first stress symptom occurred as reduced methane yield when HRT dropped below 17 h. When HRT dropped below 4 h the propionate removal stopped. The yield from acetate removal was constant at 0.17 g COD acetate removed per g CODT substrate. This robust methanogenesis implies that pig manure supernatant, and probably other similar slurries, can be digested for methane production in compact and effective sludge bed reactors. Denaturing gradient gel electrophoresis (DGGE) analysis indicated a relatively fast adaptation of the microbial communities to manure and implies that non-adapted granular sludge can be used to start such sludge bed bioreactors. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner

NASA Astrophysics Data System (ADS)

Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

2016-03-01

In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

High-efficiency removal of phytic acid in soy meal using two-stage temperature-induced Aspergillus oryzae solid-state fermentation.

PubMed

Chen, Liyan; Vadlani, Praveen V; Madl, Ronald L

2014-01-15

Phytic acid of soy meal (SM) could influence protein and important mineral digestion of monogastric animals. Aspergillus oryzae (ATCC 9362) solid-state fermentation was applied to degrade phytic acid in SM. Two-stage temperature fermentation protocol was investigated to increase the degradation rate. The first stage was to maximize phytase production and the second stage was to realize the maximum enzymatic degradation. In the first stage, a combination of 41% moisture, a temperature of 37 °C and inoculum size of 1.7 mL in 5 g substrate (dry matter basis) favored maximum phytase production, yielding phytase activity of 58.7 U, optimized via central composite design. By the end of second-stage fermentation, 57% phytic acid was degraded from SM fermented at 50 °C, compared with 39% of that fermented at 37 °C. The nutritional profile of fermented SM was also studied. Oligosaccharides were totally removed after fermentation and 67% of total non-reducing polysaccharides were decreased. Protein content increased by 9.5%. Two-stage temperature protocol achieved better phytic acid degradation during A. oryzae solid state fermentation. The fermented SM has lower antinutritional factors (phytic acid, oligosaccharides and non-reducing polysaccharides) and higher nutritional value for animal feed. © 2013 Society of Chemical Industry.

Method for in situ combustion

DOEpatents

Pasini, III, Joseph; Shuck, Lowell Z.; Overbey, Jr., William K.

1977-01-01

This invention relates to an improved in situ combustion method for the recovery of hydrocarbons from subterranean earth formations containing carbonaceous material. The method is practiced by penetrating the subterranean earth formation with a borehole projecting into the coal bed along a horizontal plane and extending along a plane disposed perpendicular to the plane of maximum permeability. The subterranean earth formation is also penetrated with a plurality of spaced-apart vertical boreholes disposed along a plane spaced from and generally parallel to that of the horizontal borehole. Fractures are then induced at each of the vertical boreholes which project from the vertical boreholes along the plane of maximum permeability and intersect the horizontal borehole. The combustion is initiated at the horizontal borehole and the products of combustion and fluids displaced from the earth formation by the combustion are removed from the subterranean earth formation via the vertical boreholes. Each of the vertical boreholes are, in turn, provided with suitable flow controls for regulating the flow of fluid from the combustion zone and the earth formation so as to control the configuration and rate of propagation of the combustion zone. The fractures provide a positive communication with the combustion zone so as to facilitate the removal of the products resulting from the combustion of the carbonaceous material.

Geophysical Potential for Wind Energy over the Open Oceans

NASA Astrophysics Data System (ADS)

Possner, A.; Caldeira, K.

2017-12-01

Wind turbines continuously remove kinetic energy from the lower troposphere thereby reducing the wind speed near hub height. The rate of electricity generation in large wind farms containing multiple wind arrays is therefore constrained by the rate of kinetic energy replenishment from the atmosphere above. In particular, this study focuses on the maximum sustained transport of kinetic energy through the troposphere to the lowest hundreds of meters above the surface. In recent years, a growing body of research argues that the rate of generated power is limited to around 1.5 Wm-2 within large wind farms. However, in this study we demonstrate that considerably higher power generation rates may be sustainable over some open ocean areas in giant wind farms. We find that in the North Atlantic maximum extraction rates of up to 6.7 Wm-2 may be sustained by the atmosphere in the annual mean over giant wind farm areas approaching the size of Greenland. In contrast, only a third of this rate is sustained on land for areas of equivalent size. Our simulations indicate a fundamental difference in response of the troposphere and its vertical kinetic energy flux to giant near-surface wind farms. We find that the surface heat flux from the oceans to the atmosphere may play an important role in creating regions where large sustained rates of downward transport of kinetic energy and thus rates of kinetic energy extraction may be geophysically possible. While no commercial-scale deep-water wind turbines yet exist, our results suggest that such technologies, if they became technically and economically feasible, could potentially provide civilization-scale power.

Selective Removal of Residual Orthodontic Composite Using a Rapidly Scanned Carbon Dioxide Laser with Spectral Feedback

NASA Astrophysics Data System (ADS)

Hirasuna, Krista

Background and Objective: Excessive heat accumulation within the tooth, incomplete removal of composite, and variable damage to the enamel are shortcomings of using conventional burs to remove residual orthodontic composite after debonding fixed appliances. The objective of this study was to determine if composite could be selectively removed from the enamel surface using a rapidly scanned carbon dioxide laser controlled by spectral feedback. Materials and Methods: A carbon dioxide laser operating at a wavelength of 9.3 microm with a pulse duration of 10-15 micros and a pulse repetition rate of ˜ 200 Hz was used to selectively remove composite from the buccal surfaces of 21 extracted teeth. GrenGloo(TM) composite was used to better visualize residual composite and the amount of enamel lost was measured with optical microscopy. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Results: The amount of enamel lost averaged 22.7microm +/- 8.9 and 25.3 microm +/- 9.4 for removal at 3.8 and 4.2 J/cm2, respectively. An average maximum temperature rise of 1.9°C +/- 1.5 was recorded, with no teeth approaching the critical value of 5.5°C. The average time of composite removal was 19.3 +/- 4.1 seconds. Conclusions: Residual orthodontic composite can be rapidly removed from the tooth surface using a rapidly scanned CO2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal damage to the underlying enamel surface.

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.

Removal of arsenic from water using manganese (III) oxide: Adsorption of As(III) and As(V).

PubMed

Babaeivelni, Kamel; Khodadoust, Amid P

2016-01-01

Removal of arsenic from water was evaluated with manganese (III) oxide (Mn2O3) as adsorbent. Adsorption of As(III) and As(V) onto Mn2O3 was favorable according to the Langmuir and Freundlich adsorption equilibrium equations, while chemisorption of arsenic occurred according to the Dubinin-Radushkevich equation. Adsorption parameters from the Langmuir, Freundlich, and Temkin equations showed a greater adsorption and removal of As(III) than As(V) by Mn2O3. Maximum removal of As(III) and As(V) occurred at pH 3-9 and at pH 2, respectively, while removal of As(V) in the pH range of 6-9 was 93% (pH 6) to 61% (pH 9) of the maximum removal. Zeta potential measurements for Mn2O3 in As(III) was likely converted to As(V) solutions indicated that As(III) was likely converted to As(V) on the Mn2O3 surface at pH 3-9. Overall, the effective Mn2O3 sorbent rapidly removed As(III) and As(V) from water in the pH range of 6-9 for natural waters.

Allyl triphenyl phosphonium bromide based DES-functionalized carbon nanotubes for the removal of mercury from water.

PubMed

AlOmar, Mohamed Khalid; Alsaadi, Mohammed Abdulhakim; Hayyan, Maan; Akib, Shatirah; Ibrahim, Muhammad; Hashim, Mohd Ali

2017-01-01

Recently, deep eutectic solvents (DESs) have shown their new and interesting ability for chemistry through their involvement in variety of applications. This study introduces carbon nanotubes (CNTs) functionalized with DES as a novel adsorbent for Hg 2+ from water. Allyl triphenyl phosphonium bromide (ATPB) was combined with glycerol as the hydrogen bond donor (HBD) to form DES, which can act as a novel CNTs functionalization agent. The novel adsorbent was characterized using Raman, FTIR, XRD, FESEM, EDX, BET surface area, TGA, TEM and Zeta potential. Response surface methodology was used to optimize the removal conditions for Hg 2+ . The optimum removal conditions were found to be pH 5.5, contact time 28 min, and an adsorbent dosage of 5 mg. Freundlich isotherm model described the adsorption isotherm of the novel adsorbent, and the maximum adsorption capacity obtained from the experimental data was 186.97 mg g -1 . Pseudo-second order kinetics describes the adsorption rate order. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous carbon and nitrogen removal using an oxic/anoxic-biocathode microbial fuel cells coupled system.

PubMed

Xie, Shan; Liang, Peng; Chen, Yang; Xia, Xue; Huang, Xia

2011-01-01

A coupled microbial fuel cell (MFC) system comprising of an oxic-biocathode MFC (O-MFC) and an anoxic-biocathode MFC (A-MFC) was implemented for simultaneous removal of carbon and nitrogen from a synthetic wastewater. The chemical oxygen demand (COD) of the influent was mainly reduced at the anodes of the two MFCs; ammonium was oxidized to nitrate in the O-MFC's cathode, and nitrate was electrochemically denitrified in the A-MFC's cathode. The coupled MFC system reached power densities of 14 W/m(3) net cathodic compartment (NCC) and 7.2 W/m(3) NCC for the O-MFC and the A-MFC, respectively. In addition, the MFC system obtained a maximum COD, NH(4)(+)-N and TN removal rate of 98.8%, 97.4% and 97.3%, respectively, at an A-MFC external resistance of 5 Ω, a recirculation ratio (recirculated flow to total influent flow) of 2:1, and an influent flow ratio (O-MFC anode flow to A-MFC anode flow) of 1:1. Copyright © 2010 Elsevier Ltd. All rights reserved.

Diesel oil removal by immobilized Pseudoxanthomonas sp. RN402.

PubMed

Nopcharoenkul, Wannarak; Netsakulnee, Parichat; Pinyakong, Onruthai

2013-06-01

Pseudoxanthomonas sp. RN402 was capable of degrading diesel, crude oil, n-tetradecane and n-hexadecane. The RN402 cells were immobilized on the surface of high-density polyethylene plastic pellets at a maximum cell density of 10(8) most probable number (MPN) g(-1) of plastic pellets. The immobilized cells not only showed a higher efficacy of diesel oil removal than free cells but could also degrade higher concentrations of diesel oil. The rate of diesel oil removal by immobilized RN402 cells in liquid culture was 1,050 mg l(-1) day(-1). Moreover, the immobilized cells could maintain high efficacy and viability throughout 70 cycles of bioremedial treatment of diesel-contaminated water. The stability of diesel oil degradation in the immobilized cells resulted from the ability of living RN402 cells to attach to material surfaces by biofilm formation, as was shown by CLSM imaging. These characteristics of the immobilized RN402 cells, including high degradative efficacy, stability and flotation, make them suitable for the purpose of continuous wastewater bioremediation.

Synthesis, performance, and modeling of immobilized nano-sized magnetite layer for phosphate removal.

PubMed

Zach-Maor, Adva; Semiat, Raphael; Shemer, Hilla

2011-05-15

A homogeneous layer of nano-sized magnetite particles (<4 nm) was synthesized by impregnation of modified granular activated carbon (GAC) with ferric chloride, for effective removal of phosphate. A proposed mechanism for the modification and formation of magnetite onto the GAC is specified. BET results showed a significant increase in the surface area of the matrix following iron loading, implying that a porous nanomagnetite layer was formed. Batch adsorption experiments revealed high efficiency of phosphate removal, by the newly developed adsorbent, attaining maximum adsorption capacity of 435 mg PO(4)/g Fe (corresponding to 1.1 mol PO(4)/mol Fe(3)O(4)). It was concluded that initially phosphate was adsorbed by the active sites on the magnetite surface, and then it diffused into the interior pores of the nanomagnetite layer. It was demonstrated that the latter is the rate-determining step for the process. Innovative correlation of the diffusion mechanism with the unique adsorption properties of the synthesized adsorbent is presented. Copyright © 2011 Elsevier Inc. All rights reserved.

Effect of NaX zeolite-modified graphite felts on hexavalent chromium removal in biocathode microbial fuel cells.

PubMed

Wu, Xiayuan; Tong, Fei; Yong, Xiaoyu; Zhou, Jun; Zhang, Lixiong; Jia, Honghua; Wei, Ping

2016-05-05

Two kinds of NaX zeolite-modified graphite felts were used as biocathode electrodes in hexavalent chromium (Cr(VI))-reducing microbial fuel cells (MFCs). The one was fabricated through direct modification, and the other one processed by HNO3 pretreatment of graphite felt before modification. The results showed that two NaX zeolite-modified graphite felts are excellent bio-electrode materials for MFCs, and that a large NaX loading mass, obtained by HNO3 pretreatment (the HNO3-NaX electrode), leads to a superior performance. The HNO3-NaX electrode significantly improved the electricity generation and Cr(VI) removal of the MFC. The maximum Cr(VI) removal rate increased to 10.39±0.28 mg/L h, which was 8.2 times higher than that of the unmodified control. The improvement was ascribed to the strong affinity that NaX zeolite particles, present in large number on the graphite felt, have for microorganisms and Cr(VI) ions. Copyright © 2016 Elsevier B.V. All rights reserved.

Ozone disintegration of excess biomass and application to nitrogen removal.

PubMed

Park, Ki Young; Lee, Jae Woo; Ahn, Kyu-Hong; Maeng, Sung Kyu; Hwang, Jong Hyuk; Song, Kyung-Guen

2004-01-01

A pilot-scale facility integrated with an ozonation unit was built to investigate the feasibility of using ozone-disintegration byproducts of wasted biomass as a carbon source for denitrification. Ozonation of biomass resulted in mass reduction by mineralization as well as by ozone-disintegrated biosolids recycling. Approximately 50% of wasted solids were recovered as available organic matter (ozonolysate), which included nonsettleable microparticles and soluble fractions. Microparticles were observed in abundance at relatively low levels of ozone doses, while soluble fractions became dominant at higher levels of ozone doses in ozone-disintegrated organics. Batch denitrification experiments showed that the ozonolysate could be used as a carbon source with a maximum denitrification rate of 3.66 mg nitrogen (N)/g volatile suspended solids (VSS) x h. Ozonolysate was also proven to enhance total nitrogen removal efficiency in the pilot-scale treatment facility. An optimal chemical oxygen demand (COD)-to-nitrogen ratio for complete denitrification was estimated as 5.13 g COD/g N. The nitrogen-removal performance of the modified intermittently decanted extended aeration process dependent on an external carbon supply could be described as a function of solids retention time.

Avian Conservation Practices Strengthen Ecosystem Services in California Vineyards

PubMed Central

Jedlicka, Julie A.; Greenberg, Russell; Letourneau, Deborah K.

2011-01-01

Insectivorous Western Bluebirds (Sialia mexicana) occupy vineyard nest boxes established by California winegrape growers who want to encourage avian conservation. Experimentally, the provision of available nest sites serves as an alternative to exclosure methods for isolating the potential ecosystem services provided by foraging birds. We compared the abundance and species richness of avian foragers and removal rates of sentinel prey in treatments with songbird nest boxes and controls without nest boxes. The average species richness of avian insectivores increased by over 50 percent compared to controls. Insectivorous bird density nearly quadrupled, primarily due to a tenfold increase in Western Bluebird abundance. In contrast, there was no significant difference in the abundance of omnivorous or granivorous bird species some of which opportunistically forage on grapes. In a sentinel prey experiment, 2.4 times more live beet armyworms (Spodoptera exigua) were removed in the nest box treatment than in the control. As an estimate of the maximum foraging services provided by insectivorous birds, we found that larval removal rates measured immediately below occupied boxes averaged 3.5 times greater than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices. Predator addition and sentinel prey experiments lack some disadvantages of predator exclusion experiments and were robust methodologies for detecting ecosystem services. PMID:22096555

Depositional fluxes and residence time of atmospheric radioiodine (131I) from the Fukushima accident.

PubMed

Yang, Weifeng; Guo, Laodong

2012-11-01

Activities of radioiodine ((131)I) along with (210)Pb and (210)Po in time series precipitation samples were measured to determine the depositional fluxes of (131)I in the Southern United States and its removal rate and residence time in the atmosphere during the Fukushima nuclear accident. Radioiodine released from the Fukushima accident reached the Southern United States within 11 days, giving rise to a concurrent (131)I peak and anomalous (210)Po/(210)Pb ratios in the precipitation samples. The cumulative (131)I depositional flux was 4.6 ± 0.2 Bq m(-2) during the maximum fallout. The removal rate of (131)I out of the atmosphere, derived from a definite (131)I integral model, ranged from 0.03 to 0.14 d(-1) with an average of 0.08 ± 0.02 d(-1), which corresponds to a residence time of (131)I in the atmosphere of 12 ± 3 days, consistent with the resident timescale constrained by the (210)Po/(210)Pb disequilibrium technique. These results support our hypothesis that radioiodine was removed from the atmosphere by precipitation within two weeks. It seemed that regions reachable by (131)I transport within two weeks from Fukushima Japan would receive much more fallout, whereas places outside that distance would be relatively less polluted with radionuclides. Copyright © 2012 Elsevier Ltd. All rights reserved.

Metaldehyde removal from aqueous solution by adsorption and ion exchange mechanisms onto activated carbon and polymeric sorbents.

PubMed

Tao, Bing; Fletcher, Ashleigh J

2013-01-15

Metaldehyde removal from aqueous solution was evaluated using granular activated carbon (GAC), a non-functionalised hyper-cross-linked polymer Macronet (MN200) and an ion-exchange resin (S957) with sulfonic and phosphonic functional groups. Equilibrium experimental data were successfully described by Freundlich isotherm models. The maximum adsorption capacity of S957 (7.5 g metaldehyde/g S957) exceeded those of MN200 and GAC. Thermodynamic studies showed that sorption of metaldehyde onto all sorbents is endothermic and processes are controlled by entropic rather than enthalpic changes. Kinetic experiments demonstrated that experimental data for MN200 and GAC obey pseudo-second order models with rates limited by particle diffusion. Comparatively, S957 was shown to obey a pseudo-first order model with a rate-limiting step of metaldehyde diffusion through the solid/liquid interface. Results obtained suggest that metaldehyde adsorption onto MN200 and GAC are driven by hydrophobic interactions and hydrogen bonding, as leaching tendencies were high since no degradation of metaldehyde occurred. Conversely, adsorption of metaldehyde onto S957 occurs via ion-exchange processes, where sulfonic and phosphonic functionalities degrade adsorbed metaldehyde molecules and failure to detect metaldehyde in leaching studies for S957 supports this theory. Consequently, the high adsorption capacity and absence of leaching indicate S957 is promising for metaldehyde removal from source water. Copyright © 2012 Elsevier B.V. All rights reserved.

Nitrogen removal process optimization in New York City WPCPS: a case study of Wards Island WPCP.

PubMed

Ramalingam, K; Fillos, J; Musabyimana, M; Deur, A; Beckmann, K

2009-01-01

The New York City Department of Environmental Protection has been engaged in a continuous process to develop a nitrogen removal program to reduce the nitrogen mass discharge from its water pollution control plants, (WPCPs), from 49,158 kg/d to 20,105 kg/d by the year 2017 as recommended by the Long Island Sound Study. As part of the process, a comprehensive research effort was undertaken involving bench, pilot and full scale studies to identify the most effective way to upgrade and optimize the existing WPCPs. Aeration tank 13 (AT-13) at the Wards Island WPCP was particularly attractive as a full-scale research facility because its aeration tank with its dedicated final settling tanks and RAS pumps could be isolated from the remaining treatment facilities. The nitrogen removal performance of AT-13, which, at the time, was operated as a "basic step feed BNR Facility", was evaluated and concurrently nitrification kinetic parameters were measured using in-situ bench scale experiments. Additional bench scale experiments provided denitrification rates using different sources of carbon and measurement of the maximum specific growth rate of nitrifying bacteria. The combined findings were then used to upgrade AT-13 to a "full" BNR facility with carbon and alkalinity addition. This paper will focus on the combined bench and full scale results that were the basis for the consequent upgrade.

Avian conservation practices strengthen ecosystem services in California vineyards.

PubMed

Jedlicka, Julie A; Greenberg, Russell; Letourneau, Deborah K

2011-01-01

Insectivorous Western Bluebirds (Sialia mexicana) occupy vineyard nest boxes established by California winegrape growers who want to encourage avian conservation. Experimentally, the provision of available nest sites serves as an alternative to exclosure methods for isolating the potential ecosystem services provided by foraging birds. We compared the abundance and species richness of avian foragers and removal rates of sentinel prey in treatments with songbird nest boxes and controls without nest boxes. The average species richness of avian insectivores increased by over 50 percent compared to controls. Insectivorous bird density nearly quadrupled, primarily due to a tenfold increase in Western Bluebird abundance. In contrast, there was no significant difference in the abundance of omnivorous or granivorous bird species some of which opportunistically forage on grapes. In a sentinel prey experiment, 2.4 times more live beet armyworms (Spodoptera exigua) were removed in the nest box treatment than in the control. As an estimate of the maximum foraging services provided by insectivorous birds, we found that larval removal rates measured immediately below occupied boxes averaged 3.5 times greater than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices. Predator addition and sentinel prey experiments lack some disadvantages of predator exclusion experiments and were robust methodologies for detecting ecosystem services.

The significance of denitrifying polyphosphate accumulating organisms in biological nutrient removal activated sludge systems.

PubMed

Hu, Z R; Wentzel, M C; Ekama, G A

2002-01-01

In this paper the advantages and disadvantages of denitrifying PAOs (polyphosphate accumulating organisms) in conventional BNRAS (biological nutrient removal activated sludge) and external nitrification BNRAS (ENBNRAS) systems are evaluated, with experimental data exhibiting a range of anoxic P uptake from low (<10%) to very high (>60%). The results indicate that the specific denitrification rate of the PAOs on internally stored PHB COD is about 1/5th of that of the "ordinary" heterotrophic organisms on SBCOD, and the PAOs contribute little (maximum 20%) to the denitrification in BNRAS systems even when the anoxic P uptake is high (60% of the total P uptake). Considering the unpredictable nature of anoxic P uptake and the reduction in BEPR it causes compared with aerobic P uptake BEPR, it is concluded that anoxic P uptake does not add a significant advantage to the BNR system.

Preparation and Adsorption Property of Imido-acetic Acid Type Chelating Nano-fibers by Electro-spinning Technique

NASA Astrophysics Data System (ADS)

Yang, Jiali; Lu, Lansi; Zhang, Zhu; Liao, Minhui; He, Huirong; Li, Lingxing; Chen, Jida; Chen, Shijin

2017-12-01

A novel nano-fibrous adsorbent from imino-acetic acid (IDA) and polyvinyl alcohol (PVA) mixture solution was prepared by electro-spinning technique. The nano-fibrous adsorbents with imino-acetic acid functional groups were characterized and demonstrated by fourier transform infrared spectrometry (FT-IR) and the scanning electron microscopy (SEM). The effect of the adsorbents to remove heavy metals such as lead (Pb) and copper (Cu) ions from the aqueous solution was studied. The maximum adsorption percentage (SP) of the metal ions can reach 93.08% for Cu (II) and 96.69% for Pb(II), respectively. Furthermore, it shows that the adsorption procedure of the adsorbents is spontaneous and endothermic, and adsorption rate fits well with pseudo-second-order kinetic model. Most importantly, the reusability of the nanofibers for removal of metal ions was also demonstrated to be used at least five times.

Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

PubMed

Karagiannidis, Christian; Kampe, Kristin Aufm; Sipmann, Fernando Suarez; Larsson, Anders; Hedenstierna, Goran; Windisch, Wolfram; Mueller, Thomas

2014-06-17

While non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH <7.20) still need intubation. Extracorporeal veno-venous CO2 removal (ECCO2R) could prove to be an alternative. The present animal study tested in a systematic fashion technical requirements for successful ECCO2R in terms of cannula size, blood and sweep gas flow. ECCO2R with a 0.98 m(2) surface oxygenator was performed in six acidotic (pH <7.20) pigs using either a 14.5 French (Fr) or a 19Fr catheter, with sweep gas flow rates of 8 and 16 L/minute, respectively. During each experiment the blood flow was incrementally increased to a maximum of 400 mL/minute (14.5Fr catheter) and 1000 mL/minute (19Fr catheter). Amelioration of severe respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH. Veno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

Application of magnetic ionomer for development of very fast and highly efficient uptake of triazo dye Direct Blue 71 form different water samples.

PubMed

Khani, Rouhollah; Sobhani, Sara; Beyki, Mostafa Hossein; Miri, Simin

2018-04-15

This research focuses on removing Direct Blue 71 (DB 71) from aqueous solution in an efficient and very fast route by ionic liquid mediated γ-Fe 2 O 3 magnetic ionomer. 2-hydroxyethylammonium sulphonate immobilized on γ-Fe 2 O 3 nanoparticles (γ-Fe 2 O 3 -2-HEAS) was used for this purpose. The influence of shaking time, medium pH, the concentration of sorbent and NaNO 3 on removal was evaluated to greatly influence removal extent. The optimal removal conditions were determined by response surface methodology based on the four-variable central composite design to obtain maximum removal efficiency and determine the significance and interaction effect of the variables on the removal of target triazo dye. The results have shown that an amount of 98.2% as % removal under the optimum conditions. The adsorption kinetics and isotherms were well fitted to a pseudo-second order model and Freundlich model, respectively. Based on these models, the maximum dye adsorption capacity (Q m ) of 47.60mgg -1 was obtained. Finally, the proposed nano-adsorbent was applied satisfactorily for removal of target triazo dye from different water samples. Copyright © 2017 Elsevier Inc. All rights reserved.

Fenton Oxidation Kinetics and Intermediates of Nonylphenol Ethoxylates

PubMed Central

Cui, Kai; Yi, Hao; Zhou, Zi-jian; Zhuo, Qiong-fang; Bing, Yong-xin; Guo, Qing-wei; Xu, Zhen-cheng

2014-01-01

Abstract Removal of nonylphenol ethoxylates (NPEOs) in aqueous solution by Fenton oxidation process was studied in a laboratory-scale batch reactor. Operating parameters, including initial pH temperature, hydrogen peroxide, and ferrous ion dosage, were thoroughly investigated. Maximum NPEOs reduction of 84% was achieved within 6 min, under an initial pH of 3.0, 25°C, an H2O2 dosage of 9.74×10−3 M, and a molar ratio of [H2O2]/[Fe2+] of 3. A modified pseudo-first-order kinetic model was found to well represent experimental results. Correlations of reaction rate constants and operational parameters were established based on experimental data. Results indicated that the Fenton oxidation rate and removal efficiency were more dependent on the dosage of H2O2 than Fe2+, and the apparent activation energy (ΔE) was 17.5 kJ/mol. High-performance liquid chromatography and gas chromatograph mass spectrometer analytical results indicated degradation of NPEOs obtained within the first 2 min stepwise occurred by ethoxyl (EO) unit shortening. Long-chain NPEOs mixture demonstrated a higher degradation rate than shorter-chain ones. Nonylphenol (NP), short-chain NPEOs, and NP carboxyethoxylates were identified as the primary intermediates, which were mostly further degraded. PMID:24868141

A simple analytical method to estimate all exit parameters of a cross-flow air dehumidifier using liquid desiccant

PubMed Central

Bassuoni, M.M.

2013-01-01

The dehumidifier is a key component in liquid desiccant air-conditioning systems. Analytical solutions have more advantages than numerical solutions in studying the dehumidifier performance parameters. This paper presents the performance results of exit parameters from an analytical model of an adiabatic cross-flow liquid desiccant air dehumidifier. Calcium chloride is used as desiccant material in this investigation. A program performing the analytical solution is developed using the engineering equation solver software. Good accuracy has been found between analytical solution and reliable experimental results with a maximum deviation of +6.63% and −5.65% in the moisture removal rate. The method developed here can be used in the quick prediction of the dehumidifier performance. The exit parameters from the dehumidifier are evaluated under the effects of variables such as air temperature and humidity, desiccant temperature and concentration, and air to desiccant flow rates. The results show that hot humid air and desiccant concentration have the greatest impact on the performance of the dehumidifier. The moisture removal rate is decreased with increasing both air inlet temperature and desiccant temperature while increases with increasing air to solution mass ratio, inlet desiccant concentration, and inlet air humidity ratio. PMID:25685485

[Electricity generation from sweet potato fuel ethanol wastewater using microbial fuel cell technology].

PubMed

Cai, Xiao-Bo; Yang, Yi; Sun, Yan-Ping; Zhang, Liang; Xiao, Yao; Zhao, Hai

2010-10-01

Air cathode microbial fuel cell (MFC) were investigated for electricity production from sweet potato fuel ethanol wastewater containing 5000 mg/L of chemical oxygen demand (COD). Maximum power density of 334.1 mW/m2, coulombic efficiency (CE) of 10.1% and COD removal efficiency of 92.2% were approached. The effect of phosphate buffer solution (PBS) and COD concentration on the performance of MFC was further examined. The addition of PBS from 50 mmol/L to 200 mmol/L increased the maximum power density and CE by 33.4% and 26.0%, respectively. However, the COD removal efficiency was not relative to PBS concentration in the wastewater. When the COD increased from 625 mg/L to 10 000 mg/L, the maximum value of COD removal efficiency and the maximum power density were gained at the wastewater strength of 5 000 mg/L. But the CE ranged from 28.9% to 10.3% with a decreasing trend. These results demonstrate that sweet potato fuel ethanol wastewater can be used for electricity generation in MFC while at the same time achieving wastewater treatment. The increasing of PBS concentration can improve the power generation of MFC. The maximum power density of MFC increases with the rise of COD concentration, but the electricity generation will decrease for the acidification of high wastewater concentration.

Effectiveness of vegetation buffers surrounding playa wetlands at contaminant and sediment amelioration

USGS Publications Warehouse

Haukos, David A.; Johnson, Lacrecia A.; Smith, Loren M.; McMurry, Scott T.

2016-01-01

Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and transported by precipitation from surrounding cultivated watersheds. We evaluated effectiveness of vegetative buffers surrounding playas in removing metals, nutrients, and dissolved/suspended sediments from precipitation runoff. Storm water runoff was collected at 10-m intervals in three buffer types (native grass, fallow cropland, and Conservation Reserve Program). Buffer type differed in plant composition, but not in maximum percent removal of contaminants. Within the initial 60 m from a cultivated field, vegetation buffers of all types removed >50% of all measured contaminants, including 83% of total suspended solids (TSS) and 58% of total dissolved solids (TDS). Buffers removed an average of 70% of P and 78% of N to reduce nutrients entering the playa. Mean maximum percent removal for metals ranged from 56% of Na to 87% of Cr. Maximum removal was typically at 50 m of buffer width. Measures of TSS were correlated with all measures of metals and nutrients except for N, which was correlated with TDS. Any buffer type with >80% vegetation cover and 30–60 m in width would maximize contaminant removal from precipitation runoff while ensuring that playas would continue to function hydrologically to provide ecosystem services. Watershed management to minimize erosion and creations of vegetation buffers could be economical and effective conservation tools for playa wetlands.

Isolation, screening and molecular identification of novel bacterial strain removing methylene blue from water solutions

NASA Astrophysics Data System (ADS)

Kilany, Mona

2017-11-01

The potentially deleterious effects of methylene blue (MB) on human health drove the interest in its removal promptly. Bioremediation is an effective and eco friendly for removing MB. Soil bacteria were isolated and examined for their potential to remove MB. The most potent bacterial candidate was characterized and identified using 16S rRNA sequence technique. The evolutionary history of the isolate was conducted by maximum likelihood method. Some physiochemical parameters were optimized for maximum decolorization. Decolorization mechanism and microbial toxicity study of MB (100 mg/l) and by-products were investigated. Participation of heat killed bacteria in color adsorption have been investigated too. The bacterial isolate was identified as Stenotrophomonas maltophilia strain Kilany_MB 16S ribosomal RNA gene with 99% sequence similarity. The sequence was submitted to NCBI (Accession number = KU533726). Phylogeny depicted the phylogenetic relationships between 16S ribosomal RNA gene, partial sequence (1442 bp), of the isolated strain and other strains related to Stenotrophomonas maltophilia in the GenBank database. The optimal conditions were investigated to be pH 5 at 30 °C, after 24 h using 5 mg/l MB showing optimum decolorization percentage (61.3%). Microbial toxicity study demonstrated relative reduction in the toxicity of MB decolorized products on test bacteria. Mechanism of color removal was proved by both biosorption and biodegradation, where heat-killed and live cells showed 43 and 52% of decolorization, respectively, as a maximum value after 24-h incubation. It was demonstrated that the mechanism of color removal is by adsorption. Therefore, good performance of S maltophilia in MB color removal reinforces the exploitation of these bacteria in environmental clean-up and restoration of the ecosystem.

Experimental study of the combined calcination and hydrodesulfurization of high-sulfur green petroleum coke

NASA Astrophysics Data System (ADS)

Kilic, Saliha Meltem

The primary production of aluminum is done by means of the Hall-Heroult process where large amounts of carbon anodes are required and consumed. The quality of carbon anodes used in electrolysis is one of the most important parameters affecting the production of primary aluminum. The anode quality widely depends on the raw materials, one of which is the petroleum coke. Green petroleum coke is produced from the heavy residual fractions of petroleum. Petroleum cokes produced from sour crude oil sources contain high quantity of sulfur. A certain level of sulfur is needed to reduce the anode reactivities; however, the demand for anode-grade coke with acceptable sulfur content is increasing faster than the available supply. High sulfur levels in carbon anodes would have an adverse effect on environment; hence, the desulfurization of high sulfur green petroleum cokes is necessary. There are different ways of desulfurizing green petroleum cokes: solvent extraction, thermal desulfurization, and hydrodesulfurization. Coke produced by solvent extraction is prone to contamination. The thermal approach requires greater energy consumption and causes an increase in coke porosity. The global objective of this master project is to find an alternative solution for desulfurization that will produce quality calcined coke with minimum impact on environment. Hydrodesulfurization seems to be a viable option and was investigated in this study. Water was used for the hydrodesulfurization of commercially available high sulfur green petroleum coke. Different experimental systems were tried during the hydrodesulfurization experiments. A systematic approach was used to investigate the influence of hydrodesulfurization parameters including water injection temperature, duration, and water flow rate as well as coke particle size on the hydrodesulfurization of green petroleum coke. In addition to hydrodesulfurization, a number of thermal desulfurization experiments were carried out with the same green petroleum coke in this study. Sulfur removal as well as weight loss results which were obtained from the two methods were compared. The petroleum coke sulfur content as well as its structure were characterized using C-S analysis equipment, SEM-EDX, XPS, FT-IR, XRD, and helium pycnometer prior to the experiments. Hydrodesulfurized cokes which gave maximum sulfur removal were compared with thermally desulfurized cokes in terms of the degree of desulfurization and coke structure by using the above characterization techniques. This study has indicated that different parameters affect the rate of desulfurization to different extents. Maximum sulfur removal was obtained when the water was injected to coke surface at 1 ml/min flow rate for 60 min at 650°C and 850°C resulting in the removal of 22.87% and 22.60% sulfur, respectively. Weight loss percentages were 26.07% and 24.34%, respectively, under these conditions. Hydrodesulfurization involves the loss of a small quantity of carbon due to gasification of coke by water. The characterization of hydrodesulfurized coke with the highest desulfurization rate showed similar structure with its counterpart which was thermally desulfurized to the same maximum temperature. This result, thus, reveals that the hydrodesulfurization does not create a more porous calcined coke compared to that of thermal desulfurization. Therefore, it seems to be a promising method to produce anode-grade calcined coke with lower sulfur content and suitable structure for carbon anode production.

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%.

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.

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.

Titanium alloy vs. stainless steel miniscrews: an in vivo split-mouth study.

PubMed

Bollero, P; Di Fazio, V; Pavoni, C; Cordaro, M; Cozza, P; Lione, R

2018-04-01

To compare in vivo Titanium Alloy (TiA) with Stainless Steel (SS) miniscrews Temporary Anchorage Devices (TADs) using removal torque and Scanning Electron Microscopic (SEM) analysis. 15 subjects (6 males and 9 females) who required maximum anchorage were recruited. For each patient, a TiA TAD and a SS TAD with same length and width were implanted following a randomized split-mouth study design. Retraction was carried out with nickel-titanium spring ligated directly from the anterior hooks of the archwire to the TADs to produce 90 to 100 g of force. When no further anchorage supplementation was needed, the TADs were removed. The removal torque values were registered with a digital screwdriver. After removal, the TADs were collected in a fixed solution and examined using SEM and X-ray microanalysis. All TADs remained intact, with a 100% success rate. There was no difference in removal torque between TiA and SS miniscrews (4.4 ± 1.3 N-cm and 5.1 ± 0.7 N-cm, respectively). All specimens' loss of gloss with signs of biological contaminations resulted in a dull implant surface. SEM photomicrographs of TiA miniscrews showed predominantly blood cells while SS miniscrews showed the precipitation of an amorphous layer with low cellular component. There was no difference in spectroscopic analysis between TiA and SS miniscrews. TiA and SS miniscrews had comparable removal torque values. SEM photomicrographs showed no evidence of osseointegration with both TADs having similar biological responses.

Voice Coil Percussive Mechanism Concept for Hammer Drill

NASA Technical Reports Server (NTRS)

Okon, Avi

2009-01-01

A hammer drill design of a voice coil linear actuator, spring, linear bearings, and a hammer head was proposed. The voice coil actuator moves the hammer head to produce impact to the end of the drill bit. The spring is used to store energy on the retraction and to capture the rebound energy after each impact for use in the next impact. The maximum actuator stroke is 20 mm with the hammer mass being 200 grams. This unit can create impact energy of 0.4 J with 0.8 J being the maximum. This mechanism is less complex than previous devices meant for the same task, so it has less mass and less volume. Its impact rate and energy are easily tunable without changing major hardware components. The drill can be driven by two half-bridges. Heat is removed from the voice coil via CO2 conduction.

Response of an algal consortium to diesel under varying culture conditions.

PubMed

Chavan, Anal; Mukherji, Suparna

2010-03-01

A diesel-tolerant sessile freshwater algal consortium obtained from the vicinity of Powai Lake (Mumbai, India) was cultured in the laboratory. The presence of diesel in batch cultures enhanced the maximum specific growth rate of the algal consortium. With decrease in light-dark (L:D) cycle from 20:4 to 4:20 h, the chlorophyll-a levels decreased; however, the removal of diesel was found to be maximum at L:D of 18:6 h with 37.6% degradation over and above controls. In addition to growth in the form of green clumps, white floating biomass was found surrounding the diesel droplets on the surface. This culture predominated at the least L:D ratio of 4:20 h. Studies confirmed the ability of the floating organisms to grow heterotrophically in the dark utilizing diesel as carbon source and also in the presence of light in a medium devoid of organic carbon sources.

Analysis on the stress corrosion crack inception based on pit shape and size of the FV520B tensile specimen

NASA Astrophysics Data System (ADS)

Xiang, Longhao; Pan, Juyi; Chen, Songying

2018-06-01

The influence of pit shape and size on local stress concentration in the tensile specimen and the stress corrosion cracks inception was studied by employing the element remove technique. The maximum stress located in the bottom of pit on FV520B tensile specimen. The location of maximum strain was near the mouth of the pit or the shoulder and plastic strain existed in this region. Stress concentration factor and plastic deformation on four different geometrical shape pits of hemisphere, semi-ellipsoid, bullet and butterfly were numerically investigated, respectively. The simulation results showed that butterfly pit got the biggest stress concentration factor. The plastic strain rate during pit growth was in the sensitivity range of stress corrosion cracks inception, indicating that stress corrosion cracks were more likely to nucleate near the pit tip or the shoulder.

Statistical optimization of the phytoremediation of arsenic by Ludwigia octovalvis- in a pilot reed bed using response surface methodology (RSM) versus an artificial neural network (ANN).

PubMed

Titah, Harmin Sulistiyaning; Halmi, Mohd Izuan Effendi Bin; Abdullah, Siti Rozaimah Sheikh; Hasan, Hassimi Abu; Idris, Mushrifah; Anuar, Nurina

2018-06-07

In this study, the removal of arsenic (As) by plant, Ludwigia octovalvis, in a pilot reed bed was optimized. A Box-Behnken design was employed including a comparative analysis of both Response Surface Methodology (RSM) and an Artificial Neural Network (ANN) for the prediction of maximum arsenic removal. The predicted optimum condition using the desirability function of both models was 39 mg kg -1 for the arsenic concentration in soil, an elapsed time of 42 days (the sampling day) and an aeration rate of 0.22 L/min, with the predicted values of arsenic removal by RSM and ANN being 72.6% and 71.4%, respectively. The validation of the predicted optimum point showed an actual arsenic removal of 70.6%. This was achieved with the deviation between the validation value and the predicted values being within 3.49% (RSM) and 1.87% (ANN). The performance evaluation of the RSM and ANN models showed that ANN performs better than RSM with a higher R 2 (0.97) close to 1.0 and very small Average Absolute Deviation (AAD) (0.02) and Root Mean Square Error (RMSE) (0.004) values close to zero. Both models were appropriate for the optimization of arsenic removal with ANN demonstrating significantly higher predictive and fitting ability than RSM.

Functionalized chitosan electrospun nanofiber for effective removal of trace arsenate from water

PubMed Central

Min, Ling-Li; Zhong, Lu-Bin; Zheng, Yu-Ming; Liu, Qing; Yuan, Zhi-Huan; Yang, Li-Ming

2016-01-01

An environment-friendly iron functionalized chitosan elctrospun nanofiber (ICS-ENF) was synthesized for trace arsenate removal from water. The ICS-ENF was fabricated by electrospinning a mixture of chitosan, PEO and Fe3+ followed by crosslinking with ammonia vapor. The physicochemical properties of ICS-ENF were characterized by FESEM, TEM-EDX and XRD. The ICS-ENF was found to be highly effective for As(V) adsorption at neutral pH. The As(V) adsorption occurred rapidly and achieved equilibrium within 100 min, which was well fitted by pseudo-second-order kinetics model. The As(V) adsorption decreased with increased ionic strength, suggesting an outer-sphere complexation of As(V) on ICS-ENF. Freundlich model well described the adsorption isotherm, and the maximum adsorption capacity was up to 11.2 mg/g at pH 7.2. Coexisting anions of chloride and sulfate showed negligible influence on As(V) removal, but phosphate and silicate significantly reduced As(V) adsorption by competing for adsorption sites. FTIR and XPS analysis demonstrated –NH, –OH and C–O were responsible for As(V) uptake. ICS-ENF was easily regenerated using 0.003 M NaOH, and the removal rate remained above 98% after ten successively adsorption-desorption recycles. This study extends the potential applicability of electrospun nanofibers for water purification and provides a promising approach for As(V) removal from water. PMID:27572634

Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

PubMed

Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

2016-06-01

The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of petroleum hydrocarbons from contaminated groundwater by the combined technique of adsorption onto perlite followed by the O3/H2O2 process.

PubMed

Moussavi, Gholamreza; Bagheri, Amir

2012-09-01

Groundwater contaminated with petroleum hydrocarbons was treated using a combined system of adsorption onto powdered expanded perlite (PEP) followed by the O3/H2O2 process. The pretreatment investigations indicated a high capacity for PEP to remove petroleum hydrocarbons from the contaminated water. An experimental total petroleum hydrocarbon (TPH) adsorption capacity of 275 mg/g PEP was obtained at the natural pH of water. The experimental data fit best with the Freundlich isotherm model and pseudo-second-order adsorption model. The second phase of the experiment evaluated the performance of the O3/H2O2 process in the removal of residual TPH from pretreated water and compared the results with that of raw water. The O3/H202 process attained a maximum TPH removal rate for the pretreated water after 70 min, when 93% of the residual TPH in the effluent of the adsorption system was removed. Overall, the combination of adsorption onto PEP for 100 min and the subsequent treatment with the O3/H2O2 process for 70min eliminated over 99% of the TPH of highly petroleum-contaminated groundwater, with initial values of 162 mg/L. Therefore, we can conclude that the developed treatment system is an appropriate method of remediation for petroleum-contaminated waters.

Two methods for estimating limits to large-scale wind power generation

PubMed Central

Miller, Lee M.; Brunsell, Nathaniel A.; Mechem, David B.; Gans, Fabian; Monaghan, Andrew J.; Vautard, Robert; Keith, David W.; Kleidon, Axel

2015-01-01

Wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms. These interactions can be approximated using a vertical kinetic energy (VKE) flux method, which predicts that the maximum power generation potential is 26% of the instantaneous downward transport of kinetic energy using the preturbine climatology. We compare the energy flux method to the Weather Research and Forecasting (WRF) regional atmospheric model equipped with a wind turbine parameterization over a 105 km2 region in the central United States. The WRF simulations yield a maximum generation of 1.1 We⋅m−2, whereas the VKE method predicts the time series while underestimating the maximum generation rate by about 50%. Because VKE derives the generation limit from the preturbine climatology, potential changes in the vertical kinetic energy flux from the free atmosphere are not considered. Such changes are important at night when WRF estimates are about twice the VKE value because wind turbines interact with the decoupled nocturnal low-level jet in this region. Daytime estimates agree better to 20% because the wind turbines induce comparatively small changes to the downward kinetic energy flux. This combination of downward transport limits and wind speed reductions explains why large-scale wind power generation in windy regions is limited to about 1 We⋅m−2, with VKE capturing this combination in a comparatively simple way. PMID:26305925

Torrefaction of Durian peel and bagasse for bio-briquette as an alternative solid fuel

NASA Astrophysics Data System (ADS)

Haryati, S.; Rahmatullah; Putri, R. W.

2018-03-01

Biomass waste of durian (Durio zibethinus) peel and bagasse could be used as solid fuel by a toreffaction process. Durian peel and bagasse were washed and crushed into small sizes then dryed in order to remove water content. The treated biomass was burned at varied temperature of 200 – 350 °C and a residence time of 30 min prior to producing torrified charcoal as intermediate product. Torrified charcoal was ground into a powder blended with tapioca glue followed by casting into a cylinder to form a bio-briqquette. The bio-briquette was characterized by determining its calorific value via bomb carolimeter analysis. The key parameter of bio-briquette are calorific value and combustion rate. The result that as the burning temperature was increased the calorific value of bio-briquettes also increased. The maximum calorific value was achieved at 350°C whereas the maximum calorific value of durian (6,157 cal/gr) is higher than bagasse (6,109 cal/gr). The minimum combustion rate was attained in durian peel torrefaction at 350 °C with the rate 0.0398 g/s. The result showed that bio-briquette of durian peel and bagasse have calorific values equivalent to that of subbituminus coal in the range of 4,900 - 6,800 cal/gr.

Adsorptive removal of microcystin-LR from surface and wastewater using tyre-based powdered activated carbon: Kinetics and isotherms.

PubMed

Mashile, Phodiso P; Mpupa, Anele; Nomngongo, Philiswa N

2018-04-01

Microcystin LR (MC-LR) is a highly toxic compound and it is known for its adverse health effect on both humans and animals. Due to the ineffectiveness of conventional water treatments methods, for the past decades, researchers have been developing cost-effective ways of removing MC-LR from water bodies. This study reports the application of powdered activated carbon (PAC) obtained from the waste tyre for the removal of MC-LR. The choice of the adsorbent was chosen due to its attractive properties. The prepared tyre-based PAC was found to have the large surface area (1111 m 2  g -1 ). The detection of MC-LR was achieved using high performance liquid chromatography (HPLC) coupled with a PDA detector. The experimental parameters (such as optimum pH, dosage and contact time) affecting the removal of MC-LR using tyre based-powdered activated carbon were optimized using response surface methodology (RSM). Maximum removal of MC-LR was achieved under the following optimum conditions; sample pH 4, carbon dosage concentration 10,000 mg L -1 and contact time of 34 min. Under optimum conditions, kinetic studies and adsorption isotherms reflected better fit for pseudo-second-order rate and Langmuir isotherm model, respectively. The optimized method was applied for the removal of MC-LR in wastewater sample. The effluent and influent sample contained initial concentrations ranging from 0.52 to 8.54 μg L -1 and the removal efficiency was 100%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ammonia removal via microbial fuel cell (MFC) dynamic reactor

NASA Astrophysics Data System (ADS)

Alabiad, I.; Ali, U. F. M.; Zakarya, I. A.; Ibrahim, N.; Radzi, R. W.; Zulkurnai, N. Z.; Azmi, N. H.

2017-06-01

Landfill leachate is generally known as high-strength wastewater that is difficult to handle and contains dissolved extracts and suspended matter. Microbial fuel cells (MFCs) were designed to treat landfill leachate while continuously producing power (voltage output). Three different anodes were tested in MFC reactors: carbon black, activated carbon, and zinc electrodes. Movements in the MFC reactor during treatment were also a key factor for testing. Results showed a difference in ammonia levels in the three anodes used. The study compared the efficiency of static and dynamic modes of MFC in removing ammonia. Continual leachate movement in the reactor could increase the rate of removal of the ammonia components. The setup provided a viable condition for maximum removal because the reactor movement caused the sludge to disintegrate, which allowed ammonia to separate easily from the parent leachate. Ammonia removal also resulted from the transfer of ammonium through the membrane or from ammonia loss. Constant exchange of ionic content benefited the MFC performance by increasing power production and decreasing internal electrode material resistance. This paper presents the results of the analyses of leachate treatment from the solid waste landfill located in Padang Siding Landfill, Perlis. The performance of ammonia removal was enhanced using different types of electrodes. In both modes, activated carbon performed better than black carbon and zinc. The respective percentages of ammonia removal for activated carbon of dynamic over static were 96.6%, 66.6%, and 92.8% for activated carbon, zinc, and black carbon. The results provide further information on the possibility of using MFCs in landfill leachate treatment systems.

Arsenic and Nitrate Removal from Drinking Water by Ion Exchange U.S. EPA Demonstration Project at Vale, OR - Final Performance Evaluation Report

EPA Science Inventory

As part of the EPA Arsenic Removal Technology Demonstration Program, a 540-gal/min (gpm) ion exchange (IX) system proposed by Kinetico was selected for demonstration at Vale, OR to remove arsenic and nitrate from a groundwater supply to meet their respective maximum contaminant l...

A pre-dam-removal assessment of sediment transport for four dams on the Kalamazoo River between Plainwell and Allegan, Michigan

USGS Publications Warehouse

Syed, Atiq U.; Bennett, James P.; Rachol, Cynthia M.

2005-01-01

Four dams on the Kalamazoo River between the cities of Plainwell and Allegan, Mich., are in varying states of disrepair. The Michigan Department of Environmental Quality (MDEQ) and U.S. Environmental Protection Agency (USEPA) are considering removing these dams to restore the river channels to pre-dam conditions. This study was initiated to identify sediment characteristics, monitor sediment transport, and predict sediment resuspension and deposition under varying hydraulic conditions. The mathematical model SEDMOD was used to simulate streamflow and sediment transport using three modeling scenarios: (1) sediment transport simulations for 730 days (Jan. 2001 to Dec. 2002), with existing dam structures, (2) sediment transport simulations based on flows from the 1947 flood at the Kalamazoo River with existing dam structures, and (3) sediment transport simulations based on flows from the 1947 flood at the Kalamazoo River with dams removed. Sediment transport simulations based on the 1947 flood hydrograph provide an estimate of sediment transport rates under maximum flow conditions. These scenarios can be used as an assessment of the sediment load that may erode from the study reach at this flow magnitude during a dam failure. The model was calibrated using suspended sediment as a calibration parameter and root mean squared error (RMSE) as an objective function. Analyses of the calibrated model show a slight bias in the model results at flows higher than 75 m3/s; this means that the model-simulated suspended-sediment transport rates are higher than the observed rates; however, the overall calibrated model results show close agreement between simulated and measured values of suspended sediment. Simulation results show that the Kalamazoo River sediment transport mechanism is in a dynamic equilibrium state. Model results during the 730-day simulations indicate significant sediment erosion from the study reach at flow rates higher than 55 m3/s. Similarly, significant sediment deposition occurs during low to average flows (monthly mean flows between 25.49 m3/s and 50.97 m3/s) after a high-flow event. If the flow continues to stay in the low to average range the system shifts towards equilibrium, resulting in a balancing effect between sediment deposition and erosion rates. The 1947 flood-flow simulations show approximately 30,000 m3 more instream sediments erosion for the first 21 days of the dams removed scenario than for the existing-dams scenario, with the same initial conditions for both scenarios. Application of a locally weighted regression smoothing (LOWESS) function to simulation results of the dams removed scenario indicates a steep downtrend with high sediment transport rates during the first 21 days. In comparison, the LOWESS curve for the existing-dams scenario shows a smooth transition of sediment transport rates in response to the change in streamflow. The high erosion rates during the dams-removed scenario are due to the absence of the dams; in contrast, the presence of dams in the existing-dams scenario helps reduce sediment erosion to some extent. The overall results of 60-day simulations for the 1947 flood show no significant difference in total volume of eroded sediment between the two scenarios, because the dams in the study reach have low heads and no control gates. It is important to note that the existing-dams and dams-removed scenarios simulations are run for only 60 days; therefore, the simulations take into account the changes in sediment erosion and deposition rates only during that time period. Over an extended period, more erosion of instream sediments would be expected to occur if the dams are not properly removed than under the existing conditions. On the basis of model simulations, removal of dams would further lower the head in all the channels. This lowering of head could produce higher flow velocities in the study reach, which ultimately would result in accelerated erosion rates.

Removal of 2,4-dinitrophenol using hybrid methods based on ultrasound at an operating capacity of 7 L.

PubMed

Bagal, Manisha V; Lele, Bhagyashree J; Gogate, Parag R

2013-09-01

Sonochemical removal of 2,4-dinitrophenol (DNP) has been investigated using ultrasonic bath, with an operating capacity of 7 L, fitted with a large transducer with longitudinal vibrations having a 1 kW rated power output and operating frequency of 25 kHz. It has been revealed from calorimetric studies that maximum power is dissipated at a capacity of 7 L. The concentration of DNP has been monitored with an objective of evaluation of the efficacy of ultrasonic reactor in combination with process intensifying approaches for the removal of DNP. The effect of operating pH and additives such as hydrogen peroxide and ferrous iron activated persulfate on the extent of removal of DNP has been investigated. It has been observed that the extent of removal is greater at lower pH (pH 2.5 and 4) than at higher pH (pH 10). The combined treatment strategies such as ultrasound (US)/Fenton, US/advanced Fenton and US/CuO/H2O2 have also been investigated with an objective of obtaining complete removal of DNP using hybrid treatment strategies. The extent of removal has been found to increase significantly in US/Fenton process (98.7%) as compared to that using US alone (5.8%) which demonstrates the efficacy of the combined process. First order kinetics has been fitted for all the approaches investigated in the work. Calculations of cavitational yield indicated the superiority of the reactor design as compared to the conventional ultrasonic horn type reactors. The main intermediates formed during the process of removal of DNP have been identified. Copyright © 2013 Elsevier B.V. All rights reserved.

Role of surface energy and nano-roughness in the removal efficiency of bacterial contamination by nonwoven wipes from frequently touched surfaces

NASA Astrophysics Data System (ADS)

Edwards, Nicholas W. M.; Best, Emma L.; Connell, Simon D.; Goswami, Parikshit; Carr, Chris M.; Wilcox, Mark H.; Russell, Stephen J.

2017-12-01

Healthcare associated infections (HCAIs) are responsible for substantial patient morbidity, mortality and economic cost. Infection control strategies for reducing rates of transmission include the use of nonwoven wipes to remove pathogenic bacteria from frequently touched surfaces. Wiping is a dynamic process that involves physicochemical mechanisms to detach and transfer bacteria to fibre surfaces within the wipe. The purpose of this study was to determine the extent to which systematic changes in fibre surface energy and nano-roughness influence removal of bacteria from an abiotic polymer surface in dry wiping conditions, without liquid detergents or disinfectants. Nonwoven wipe substrates composed of two commonly used fibre types, lyocell (cellulosic) and polypropylene, with different surface energies and nano-roughnesses, were manufactured using pilot-scale nonwoven facilities to produce samples of comparable structure and dimensional properties. The surface energy and nano-roughness of some lyocell substrates were further adjusted by either oxygen (O2) or hexafluoroethane (C2F6) gas plasma treatment. Static adpression wiping of an inoculated surface under dry conditions produced removal efficiencies of between 9.4% and 15.7%, with no significant difference (p < 0.05) in the relative removal efficiencies of Escherichia coli, Staphylococcus aureus or Enterococcus faecalis. However, dynamic wiping markedly increased peak wiping efficiencies to over 50%, with a minimum increase in removal efficiency of 12.5% and a maximum increase in removal efficiency of 37.9% (all significant at p < 0.05) compared with static wiping, depending on fibre type and bacterium. In dry, dynamic wiping conditions, nonwoven wipe substrates with a surface energy closest to that of the contaminated surface produced the highest E. coli removal efficiency, while the associated increase in fibre nano-roughness abrogated this trend with S. aureus and E. faecalis.

Removal of malachite green dye from aqueous solution using mesoporous silica synthesized from 1-octyl-3-methylimidazolium chloride ionic liquid

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

Ekka, Basanti; Nayak, Soumitra Ranjan; Dash, Priyabrat, E-mail: dashp@nitrkl.ac.in, E-mail: rkpatel@nitrkl.ac.in

2016-04-13

In this research, mesoporous silica was synthesized via a modified sol-gel route using 1-octyl-3-methylimidazolium chloride and was employed to remove malachite green (MG) dye from aqueous solution. Subsequently, this material was characterized and identified by different techniques such as Fourier transform infrared spectroscopy (FT-IR), N{sub 2} adsorption-desorption method, scanning electron microscopy (SEM), and thermosgravimetric analysis (TGA). Unique properties such as high surface area and pore diameter, in addition to highly reactive atoms and presence of various functional groups make the mesoporous silica possible for efficient removal of malachite green (MG). In batch experimental set-up, optimum conditions for quantitative removal ofmore » MG by mesoporous silica was attained by varying different variables such as adsorbent dosage, initial dye concentration, contact time, and pH. Optimum values were set as pH of 8.0, 0.5 g of adsorbent at contact time of 120 min. The adsorption of MG follows the pseudo-second-order rate equation. Equilibrium data fitted well with the Freundlich model at all amount of adsorbent, while maximum adsorption capacity was 5.981 mg g{sup −}1 for 0.5 g mesoporous silica synthesized in IL.« less

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.

Nylon 6 electrospun nanofibers mat as effective sorbent for the removal of estrogens: kinetic and thermodynamic studies

PubMed Central

2014-01-01

Nylon 6 electrospun nanofibers mat was prepared via electrospinning for the removal of three estrogens, namely, diethylstilbestrol (DES), dienestrol (DS), and hexestrol (HEX) from aqueous solution. Static adsorption as well as the dynamic adsorption was evaluated by means of batch and dynamic disk flow mode, respectively. The kinetic study indicated that the adsorption of the target compounds could be well fitted by the pseudo-second-order equation, suggesting the intra-particle/membrane diffusion process as the rate-limiting step of the adsorption process. The adsorption equilibrium data were all fitted well to the Freundlich isotherm models, with a maximum adsorption capacity values in the range of 97.71 to 208.95 mg/g, which can be compared to or moderately higher than other sorbents published in the literatures. The dynamic disk mode studies indicated that the mean removal yields of three model estrogens were over 95% with a notable smaller amount of adsorbent (4 mg). Thermodynamic study revealed that the adsorption process was exothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after seven times usage. It was suggested that Nylon 6 electrospun nanofibers mat has great potential as a novel effective sorbent material for estrogens removal. PMID:25114645

Toxicological assessment and management options for boat pressure-washing wastewater.

PubMed

Gerić, Marko; Gajski, Goran; Oreščanin, Višnja; Kollar, Robert; Franekić, Jasna; Garaj-Vrhovac, Vera

2015-04-01

Boats are washed periodically for maintenance in order to remove biofoulants from hulls, which results in the generation of wastewater. This study aimed at evaluating the cyto/genotoxic and mutagenic properties of wastewater produced by pressure washing of boats. The chemical characterisation of this wastewater showed that Cu, Zn, V, Cr, Fe, Pb, and select organic contaminants exceeded the maximum allowable values from 1.7 up to 96 times. The wastewater produced negative effects on human lymphocytes resulting in decreased cell viability after 4 and 24h of exposure. Chromosome aberration, micronucleus, and comet assay parameters were significantly higher after 24h of exposure. At the same time, the Salmonella typhimurium test showed negative for both TA98 and TA100 strains at all of the concentrations tested. After the treatment of wastewater using electrochemical methods/ozonation during real scale treatment plant, removal rates of colour, turbidity and heavy metals ranged from 99.4% to 99.9%, while the removal of total organic carbon (TOC) and chemical oxygen demand (COD) was above 85%. This was reflected in the removal of the wastewater's cyto/genotoxicity, which was comparable to negative controls in all of the conducted tests, suggesting that such plants could be implemented in marinas to minimise human impact on marine systems. Copyright © 2015 Elsevier Inc. All rights reserved.

Fishing and bottom water temperature as drivers of change in maximum shell length in Atlantic surfclams (Spisula solidissima)

NASA Astrophysics Data System (ADS)

Munroe, D. M.; Narváez, D. A.; Hennen, D.; Jacobson, L.; Mann, R.; Hofmann, E. E.; Powell, E. N.; Klinck, J. M.

2016-03-01

Maximum shell length of Atlantic surfclams (Spisula solidissima) on the Middle Atlantic Bight (MAB) continental shelf, obtained from federal fishery survey data from 1982-present, has decreased by 15-20 mm. Two potential causes of this decreasing trend, fishery removal of large animals and stress due to warming bottom temperatures, were investigated using an individual-based model for post-settlement surfclams and a fifty-year hindcast of bottom water temperatures on the MAB. Simulations showed that fishing and/or warming bottom water temperature can cause decreases in maximum surfclam shell length (body size) equivalent to those observed in the fished stock. Independently, either localized fishing rates of 20% or sustained bottom temperatures that are 2 °C warmer than average conditions generate the observed decrease in maximum shell length. However, these independent conditions represent extremes and are not sustained in the MAB. The combined effects of fishing and warmer temperatures can generate simulated length decreases that are similar to observed decreases. Interannual variability in bottom water temperatures can also generate fluctuations in simulated shell length of up to 20 mm over a period of 10-15 years. If the change in maximum size is not genotypic, simulations also suggest that shell size composition of surfclam populations can recover if conditions change; however, that recovery could take a decade to become evident.

Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane.

PubMed

Liu, Hong; Logan, Bruce E

2004-07-15

Microbial fuel cells (MFCs) are typically designed as a two-chamber system with the bacteria in the anode chamber separated from the cathode chamber by a polymeric proton exchange membrane (PEM). Most MFCs use aqueous cathodes where water is bubbled with air to provide dissolved oxygen to electrode. To increase energy output and reduce the cost of MFCs, we examined power generation in an air-cathode MFC containing carbon electrodes in the presence and absence of a polymeric proton exchange membrane (PEM). Bacteria present in domestic wastewater were used as the biocatalyst, and glucose and wastewater were tested as substrates. Power density was found to be much greater than typically reported for aqueous-cathode MFCs, reaching a maximum of 262 +/- 10 mW/m2 (6.6 +/- 0.3 mW/L; liquid volume) using glucose. Removing the PEM increased the maximum power density to 494 +/- 21 mW/m2 (12.5 +/- 0.5 mW/L). Coulombic efficiency was 40-55% with the PEM and 9-12% with the PEM removed, indicating substantial oxygen diffusion into the anode chamber in the absence of the PEM. Power output increased with glucose concentration according to saturation-type kinetics, with a half saturation constant of 79 mg/L with the PEM-MFC and 103 mg/L in the MFC without a PEM (1000 omega resistor). Similar results on the effect of the PEM on power density were found using wastewater, where 28 +/- 3 mW/m2 (0.7 +/- 0.1 mW/L) (28% Coulombic efficiency) was produced with the PEM, and 146 +/- 8 mW/m2 (3.7 +/- 0.2 mW/L) (20% Coulombic efficiency) was produced when the PEM was removed. The increase in power output when a PEM was removed was attributed to a higher cathode potential as shown by an increase in the open circuit potential. An analysis based on available anode surface area and maximum bacterial growth rates suggests that mediatorless MFCs may have an upper order-of-magnitude limit in power density of 10(3) mW/m2. A cost-effective approach to achieving power densities in this range will likely require systems that do not contain a polymeric PEM in the MFC and systems based on direct oxygen transfer to a carbon cathode.

Comparison of Tc-99m GSA scintigraphy and CT volumetry for evaluation in portal vein embolization.

PubMed

Kono, Yumiko; Kariya, Shuji; Komemushi, Atsushi; Nakatani, Miyuki; Yoshida, Rie Yagi; Suzuki, Satoshi; Ha-Kawa, Sung Kil; Utsunomiya, Keita; Ueno, Yasuhiro; Satoi, Sohei; Kaibori, Masaki; Kon, Masanori; Tanigawa, Noboru

2014-08-01

To determine the correlation of the rate of change of each future remnant liver (FRL) before and after portal vein embolization (PVE), by CT volumetry and Tc-99m galactosyl human serum albumin scintigraphy (GSA scintigraphy). From December 2007 to July 2012, ten patients underwent PVE before hepatic resection. CT volumetry and GSA scintigraphy were performed before and after PVE. The FRL was divided at Cantlie's line for CT volumetry, and volume change rates before and after PVE were calculated. The maximum removal rate (Rmax) was calculated using a radiopharmacokinetic model in GSA scintigraphy. The FRL Rmax change rates before and after PVE were calculated. The correlation between the volume change rates and the Rmax change rates was analyzed. The FRL volume change rate was 1.28 ± 0.26 (mean ± SD); the FRL hypertrophied in all patients significantly (p = 0.005). The FRL Rmax change rate was 1.66 ± 0.75; excluding one patient, there was significant FRL Rmax increase (p = 0.022). Although both increased significantly, no correlation between the volume change rate and the Rmax change rate was observed. No correlation was observed between the FRL volume rate and the Rmax rate.

Integrating biofiltration with SVE: A case study

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

Lesley, M.P.; Rangan, C.R.

1996-12-01

A prototype integrated soil vacuum extraction/biofiltration system has been designed and installed at a gasoline contaminated LUST site in southern Delaware. The prototype system remediates contaminated moisture entrained in the air stream, employs automatic water level controls in the filters, and achieves maximum vapor extraction and VOC destruction efficiency with an optimum power input. In addition, the valving and piping layout allows the direction of air flow through the filters to be reversed at a given time interval, which minimizes biofouling, thereby increasing efficiency by minimizing the need for frequent cleaning. This integrated system achieves constant VOC destruction rates ofmore » 40 to 70% while maintaining optimal VOC removal rates from the subsurface. The modular design allows for easy mobilization, setup and demobilization at state-lead LUST sites throughout Delaware.« less

Supercritical water gasification of landfill leachate for hydrogen production in the presence and absence of alkali catalyst.

PubMed

Weijin, Gong; Binbin, Li; Qingyu, Wang; Zuohua, Huang; Liang, Zhao

2018-03-01

Gasification of landfill leachate in supercritical water using batch-type reactor is investigated. Alkali such as NaOH, KOH, K 2 CO 3 , Na 2 CO 3 is used as catalyst. The effect of temperature (380-500 °C), retention time (5-25 min), landfill leachate concentration (1595 mg L -1 -15,225 mg L -1 ), catalyst adding amount (1-10 wt%) on hydrogen mole fraction, hydrogen yield, carbon gasification rate, COD, TOC, TN removal efficiency are investigated. The results showed that gaseous products mainly contained hydrogen, methane, carbon dioxide and carbon monoxide without addition of catalyst. However, the main gaseous products are hydrogen and methane with addition of NaOH, KOH, K 2 CO 3 , Na 2 CO 3 . In the absence of alkali catalyst, the effect of temperature on landfill leachate gasification is positive. Hydrogen mole fraction, hydrogen yield, carbon gasification ratio increase with temperature, which maximum value being 55.6%, 107.15 mol kg -1 , 71.96% is obtained at 500 °C, respectively. Higher raw landfill leachate concentration leads to lower hydrogen production and carbon gasification rate. The suitable retention time is suggested to be 15 min for higher hydrogen production and carbon gasification rate. COD, TOC and TN removal efficiency also increase with increase of temperature, decrease of landfill leachate concentration. In the presence of catalyst, the hydrogen production is obviously promoted by addition of alkali catalyst. the effect of catalysts on hydrogen production is in the following order: NaOH ＞ KOH ＞ Na 2 CO 3  ＞ K 2 CO 3 . The maximum hydrogen mole fraction and hydrogen yield being 74.40%, 70.05 mol kg -1 is obtained with adding amount of 5 wt% NaOH at 450 °C, 28 MPa, 15 min. Copyright © 2017. Published by Elsevier Ltd.

Carbonyl sulfide removal with compost and wood chip biofilters, and in the presence of hydrogen sulfide.

PubMed

Sattler, Melanie L; Garrepalli, Divya R; Nawal, Chandraprakash S

2009-12-01

Carbonyl sulfide (COS) is an odor-causing compound and hazardous air pollutant emitted frequently from wastewater treatment facilities and chemical and primary metals industries. This study examined the effectiveness of biofiltration in removing COS. Specific objectives were to compare COS removal efficiency for various biofilter media; to determine whether hydrogen sulfide (H2S), which is frequently produced along with COS under anaerobic conditions, adversely impacts COS removal; and to determine the maximum elimination capacity of COS for use in biofilter design. Three laboratory-scale polyvinyl chloride biofilter columns were filled with up to 28 in. of biofilter media (aged compost, fresh compost, wood chips, or a compost/wood chip mixture). Inlet COS ranged from 5 to 46 parts per million (ppm) (0.10-9.0 g/m3 hr). Compost and the compost/wood chip mixture produced higher COS removal efficiencies than wood chips alone. The compost and compost/wood chip mixture had a shorter stabilization times compared with wood chips alone. Fresh versus aged compost did not impact COS removal efficiency. The presence of H2S did not adversely impact COS removal for the concentration ratios tested. The maximum elimination capacity is at least 9 g/m3 hr for COS with compost media.

Evaluation of adsorption properties of sulphurised activated carbon for the effective and economically viable removal of Zn(II) from aqueous solutions.

PubMed

Anoop Krishnan, K; Sreejalekshmi, K G; Vimexen, V; Dev, Vinu V

2016-02-01

The prospective application of sulphurised activated carbon (SAC) as an ecofriendly and cost-effective adsorbent for Zinc(II) removal from aqueous phase is evaluated, with an emphasis on kinetic and isotherm aspects. SAC was prepared from sugarcane bagasse pith obtained from local juice shops in Sree Bhadrakali Devi Temple located at Ooruttukala, Neyyattinkara, Trivandrum, India during annual festive seasons. Activated carbon modified with sulphur containing ligands was opted as the adsorbent to leverage on the affinity of Zn(II) for sulphur. We report batch-adsorption experiments for parameter optimisations aiming at maximum removal of Zn(II) from liquid-phase using SAC. Adsorption of Zn(II) onto SAC was maximum at pH 6.5. For initial concentrations of 25 and 100mgL(-1), maximum of 12.3mgg(-1) (98.2%) and 23.7mgg(-1) (94.8%) of Zn(II) was adsorbed onto SAC at pH 6.5. Kinetic and equilibrium data were best described by pseudo-second-order and Langmuir models, respectively. A maximum adsorption capacity of 147mgg(-1) was obtained for the adsorption of Zn(II) onto SAC from aqueous solutions. The reusability of the spent adsorbent was also determined. Copyright © 2015 Elsevier Inc. All rights reserved.

Equilibrium, kinetic and thermodynamic studies on the removal of U(VI) by low cost agricultural waste.

PubMed

Kausar, Abida; Bhatti, Haq Nawaz; MacKinnon, Gillian

2013-11-01

In this research, biosorption efficiency of different agro-wastes was evaluated with rice husk showing maximum biosorption capacity among the selected biosorbents. Optimization of native, SDS-treated and immobilized rice husk adsorption parameters including pH, biosorbent amount, contact time, initial U(VI) concentration and temperature for maximum U(VI) removal was investigated. Maximum biosorption capacity for native (29.56 mg g(-1)) and immobilized biomass (17.59 mg g(-1)) was observed at pH 4 while SDS-treated biomass showed maximum removal (28.08 mg g(-1)) at pH 5. The Langmuir sorption isotherm model correlated best with the U(IV) biosorption equilibrium data for the 10-100 mg L(-1) concentration range. The kinetics of the reaction followed pseudo-second order kinetic model. Thermodynamic parameters like free energy (ΔG(0)) and enthalpy (ΔH°) confirmed the spontaneous and exothermic nature of the process. Experiments to determine the regeneration capacity of the selected biosorbents and the effect of competing metal ions on biosorption capacity were also conducted. The biomass was characterized using scanning electron microscopy, surface area analysis, Fourier transformed infra-red spectroscopy and thermal gravimetric analysis. The study proved that rice husk has potential to treat uranium in wastewater. Copyright © 2013 Elsevier B.V. All rights reserved.

Modeling disturbance-based native invasive species control and its implications for management.

PubMed

Shackelford, Nancy; Renton, Michael; Perring, Michael P; Hobbs, Richard J

2013-09-01

Shifts in disturbance regime have often been linked to invasion in systems by native and nonnative species. This process can have negative effects on biodiversity and ecosystem function. Degradation may be ameliorated by the reinstatement of the disturbance regimes, such as the reintroduction of fire in pyrogenic systems. Modeling is one method through which potential outcomes of different regimes can be investigated. We created a population model to examine the control of a native invasive that is expanding and increasing in abundance due to suppressed fire. Our model, parameterized with field data from a case study of the tree Allocasuarina huegeliana in Australian sandplain heath, simulated different fire return intervals with and without the additional management effort of mechanical removal of the native invader. Population behavior under the different management options was assessed, and general estimates of potential biodiversity impacts were compared. We found that changes in fire return intervals made no significant difference in the increase and spread of the population. However, decreased fire return intervals did lower densities reached in the simulated heath patch as well as the estimated maximum biodiversity impacts. When simulating both mechanical removal and fire, we found that the effects of removal depended on the return intervals and the strategy used. Increase rates were not significantly affected by any removal strategy. However, we found that removal, particularly over the whole patch rather than focusing on satellite populations, could decrease average and maximum densities reached and thus decrease the predicted biodiversity impacts. Our simulation model shows that disturbance-based management has the potential to control native invasion in cases where shifted disturbance is the likely driver of the invasion. The increased knowledge gained through the modeling methods outlined can inform management decisions in fire regime planning that takes into consideration control of an invasive species. Although particularly applicable to native invasives, when properly informed by empirical knowledge these techniques can be expanded to management of invasion by nonnative species, either by restoring historic disturbance regimes or by instating novel regimes in innovative ways.

A 5-mm piezo-scanning fiber device for high speed ultrafast laser microsurgery

PubMed Central

Ferhanoglu, Onur; Yildirim, Murat; Subramanian, Kaushik; Ben-Yakar, Adela

2014-01-01

Towards developing precise microsurgery tools for the clinic, we previously developed image-guided miniaturized devices using low repetition rate amplified ultrafast lasers for surgery. To improve the speed of tissue removal while reducing device diameter, here we present a new 5-mm diameter device that delivers high-repetition rate laser pulses for high speed ultrafast laser microsurgery. The device consists of an air-core photonic bandgap fiber (PBF) for the delivery of high energy pulses, a piezoelectric tube actuator for fiber scanning, and two aspheric lenses for focusing the light. Its inline optical architecture provides easy alignment and substantial size reduction to 5 mm diameter as compared to our previous MEMS-scanning devices while realizing improved intensity squared (two-photon) lateral and axial resolutions of 1.16 μm and 11.46 μm, respectively. Our study also sheds light on the maximum pulse energies that can be delivered through the air-core PBF and identifies cladding damage at the input facet of the fiber as the limiting factor. We have achieved a maximum energy delivery larger than 700 nJ at 92% coupling efficiency. An in depth analysis reveals how this value is greatly affected by possible slight misalignments of the beam during coupling and the measured small beam pointing fluctuations. In the absence of these imperfections, self-phase modulation becomes the limiting factor for the maximum energy delivery, setting the theoretical upper bound to near 2 μJ for a 1-m long, 7-μm, air-core PBF. Finally, the use of a 300 kHz repetition rate fiber laser enabled rapid ablation of 150 µm x 150 µm area within only 50 ms. Such ablation speeds can now allow the surgeons to translate the surgery device as fast as ~4 mm/s to continuously remove a thin layer of a 150 µm wide tissue. Thanks to a high optical transmission efficiency of the in-line optical architecture of the device and improved resolution, we could successfully perform ablation of scarred cheek pouch tissue, drilling through a thin slice. With further development, this device can serve as a precise and high speed ultrafast laser scalpel in the clinic. PMID:25071946

Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

NASA Astrophysics Data System (ADS)

Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

2017-07-01

This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium ( q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) were determined and the positive value of (Δ H) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

Population analysis of clinical and environmental Vibrio parahaemolyticus isolated from eastern provinces in China by removing the recombinant SNPs in the MLST loci.

PubMed

Lu, Xin; Zhou, Haijian; Du, Xiaoli; Liu, Sha; Xu, Jialiang; Cui, Zhigang; Pang, Bo; Kan, Biao

2016-11-01

Vibrio parahaemolyticus is a common seafood-borne pathogenic bacterium which causes gastroenteritis in humans. Continuous surveillance on the molecular characters of the clinical and environmental V. parahaemolyticus strains needs to be conducted for the epidemiological and genetic purposes. To generate a picture of the population distribution of V. parahaemolyticus in eastern China isolated from clinical cases of gastroenteritis and environmental samples, we investigated the genetic and evolutionary relationships of the strains using the commonly used multi-locus sequence typing (MLST, in which seven house-keeping genes are used in the protocol). A highly genetic diversity within the V. parahaemolyticus population was observed but ST3 was still dominant in the clinical strains, and 103 new sequence types (ST) were found in the clinical strains by searching in the global V. parahaemolyticus MLST database. With these genetically diverse strains, we estimated the recombination rates of the loci in MLST analysis. The locus recA was found to be subject to exceptionally high rate of recombination, and the recombinant single nucleotide polymorphisms (SNPs) were also identified within the seven loci. The phylogenetic tree of the strains was re-constructed using the maximum likelihood method by removing the recombination SNPs of the seven loci, and the minimum spanning tree was re-constructed with the six loci without recA. Some changes were observed in comparison with the previously used methods, suggesting that the homologous recombination has roles in shaping the clonal structure of V. parahaemolyticus. We propose the recombination-free SNPs strategy in the clonality analysis of V. parahaemolyticus, especially when using the maximum likelihood method. Copyright © 2016. Published by Elsevier B.V.

Prospective application of Leucaena leucocephala for phytoextraction of Cd and Zn and nitrogen fixation in metal polluted soils.

PubMed

Saraswat, Shweta; Rai, J P N

2011-03-01

The study deals with phytoextraction of Zn and Cd by Leucaena leucocephala grown on effluent fed and low nitrogen soils collected from S1, S2, and S3 sites, representing decreasing metal content with increasing distance from the effluent drain. Plant nitrogen fixation potential and soil micro-biochemical attributes against metal stress were also assessed. Increasing soil metal content and plant growth enhanced metal accumulation. Relatively greater amount of Zn than Cd was accumulated by L. leucocephala, which exceeded in roots with that of other parts. Remediation factor for Cd was maximum (3.6%) in S2 grown plant. Nodule numbers, their biomass, nitrogenase activity, and leghaemoglobin content were maximum in plants grown in S3 and minimum in S1 soil having maximum metals. Maximum soil organic C, total N, C(mic), and N(mic), respiration rate, ATP content, and enzymatic activities in response to phytoremediation was recorded in S3 followed by S2 and S1. Phytoremediation for a year enhanced extractable Zn and Cd by 36% and 45%, and their total removal by 20% and 30%, respectively from S2, which suggests the possible application of L. leucocephala for the remediation of metal contaminated sites and their fertility restoration by improving microbial functionalities and N-pool.

Highly efficient nonthermal ablation of bone under bulk water with a frequency-doubled Nd:YVO4 picosecond laser

NASA Astrophysics Data System (ADS)

Tulea, C.; Caron, J.; Wahab, H.; Gehlich, N.; Hoefer, M.; Esser, D.; Jungbluth, B.; Lenenbach, A.; Noll, R.

2013-03-01

Several laser systems in the infrared wavelength range, such as Nd:YAG, Er:YAG or CO2 lasers are used for efficient ablation of bone tissue. Here the application of short pulses in coaction with a thin water film results in reduced thermal side effects. Nonetheless up to now there is no laser-process for bone cutting in a clinical environment due to lack of ablation efficiency. Investigations of laser ablation rates of bone tissue using a rinsing system and concerning bleedings have not been reported yet. In our study we investigated the ablation rates of bovine cortical bone tissue, placed 1.5 cm deep in water under laminar flow conditions, using a short pulsed (25 ps), frequency doubled (532 nm) Nd:YVO4 laser with pulse energies of 1 mJ at 20 kHz repetition rate. The enhancement of the ablation rate due to debris removal by an additional water flow from a well-directed blast pipe as well as the negative effect of the admixture of bovine serum albumin to the water were examined. Optical Coherence Tomography (OCT) was used to measure the ablated volume. An experimental study of the depth dependence of the ablation rate confirms a simplified theoretical prediction regarding Beer-Lambert law, Fresnel reflection and a Gaussian beam profile. Conducting precise incisions with widths less than 1.5 mm the maximum ablation rate was found to be 0.2 mm3/s. At depths lower than 100 μm, while the maximum depth was 3.5 mm.

Enhanced bacterial quorum aggregation on a zeolite capping layer for sustainable inhibition of ammonium release from contaminated sediment.

PubMed

Xu, Jinlan; Zhang, Haiyang; Zhao, Rong; Kong, Fanxing

2017-12-01

The main objective of this study was to investigate how signal molecules enhance bacterial quorum aggregation on a zeolite capping layer for sustainable inhibition of ammonium release from contaminated sediment. Sediment remediation experiments were carried out by using nitrifying bacteria (WGX10, WGX18), denitrifying bacteria (HF3, HF7) and two kinds of signal molecules (OHHL, C8-HSL). The results showed that nitrifying bacteria and denitrifying bacteria could significantly aggregate on zeolite after adding 1.0 μM OHHL at a C/N ratio of 7. The maximum ammonium removal of five times the amount of ammonium adsorbed was achieved when 1.0 μM OHHL was added at the C/N ratio of 7 (the bio-regeneration rate was up to 88.32%), which was 1.24-2.02 times the ammonium removal amount at C/N ratios of 3, 5, 9. The concentration of total nitrogen in the overlying water was no more than 0.8 mg/L during four rounds of sediment remediation experiments. In addition, the bio-regeneration rate was up to 71.20%, which achieved sustainable inhibition of ammonium release from contaminated sediment.

Removal of endosulfan and methoxychlor from water on carbon slurry.

PubMed

Gupta, Vinod K; Ali, Imran

2008-02-01

A carbon slurry, produced in generators of fuel-oil-based industrial generators was converted into an effective and efficient adsorbent for the removal of endosulfan and methoxychlor from aqueous solution. The adsorbent was chemically treated, activated, characterized, and used for the adsorption of endosulfan and methoxychlor pesticides. The maximum adsorption was found at 90 min, 6.5 pH, 0.025 g/L dose, and 25 degrees C temperature. Langmuir and Freundlich adsorption models were applied to analyze adsorption data, and the former was found applicable to this adsorption system in terms of relatively high regression values. The thermodynamic aspect of the process was also investigated by evaluating certain important parameters (enthalpy, free energy, and entropy of system). Kinetics of adsorption was found to follow the pseudo second order rate equation. The diffusion of pesticides into carbon slurry pores was suggested to be the rate controlling step by applying Bangham's equation. Adsorption on a column was also investigated in a continuous flow system. Adsorption efficiencies of endosulfan and methoxychlor were 34.11 and 36.06 mg/g in batch processes and 32.62 and 33.52 mg/g in column operations, respectively.

Insight into effects of antibiotics on reactor performance and evolutions of antibiotic resistance genes and microbial community in a membrane reactor.

PubMed

Wen, Qinxue; Yang, Lian; Zhao, Yaqi; Huang, Long; Chen, Zhiqiang

2018-04-01

A lab-scale anoxic/oxic-membrane bioreactor was designed to treat antibiotics containing wastewater at different antibiotics concentrations (0.5 mg/L, 1 mg/L and 3 mg/L of each antibiotic). Overall COD and NH 4 + N removal (more than 90%) were not affected during the exposure to antibiotics and good TN removal was also achieved, while TP removal was significantly affected. The maximum removal efficiency of penicillin and chlorotetracycline reached 97.15% and 96.10% respectively due to strong hydrolysis, and sulfamethoxazole reached 90.07% by biodegradation. However, 63.87% of norfloxacin maximum removal efficiency was achieved mainly by sorption. The system had good ability to reduce ARGs, peaking to more than 4 orders of magnitude, which mainly depended on the biomass retaining of the membrane module. Antibiotics concentration influenced the evolution of ARGs and bacterial communities in the reactor. This research provides great implication to reduce ARGs and antibiotics in antibiotics containing wastewater using A/O-MBR. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rapid Adsorption of Copper(II) and Lead(II) by Rice Straw/Fe3O4 Nanocomposite: Optimization, Equilibrium Isotherms, and Adsorption Kinetics Study

PubMed Central

Khandanlou, Roshanak; Ahmad, Mansor B.; Fard Masoumi, Hamid Reza; Shameli, Kamyar; Basri, Mahiran; Kalantari, Katayoon

2015-01-01

Rice straw/magnetic nanocomposites (RS/Fe3O4-NCs) were prepared via co-precipitation method for removal of Pb(II) and Cu(II) from aqueous solutions. Response surface methodology (RSM) was utilized to find the optimum conditions for removal of ions. The effects of three independent variables including initial ion concentration, removal time, and adsorbent dosage were investigated on the maximum adsorption of Pb (II) and Cu (II). The optimum conditions for the adsorption of Pb(II) and Cu(II) were obtained (100 and 60 mg/L) of initial ion concentration, (41.96 and 59.35 s) of removal time and 0.13 g of adsorbent for both ions, respectively. The maximum removal efficiencies of Pb(II) and Cu(II) were obtained 96.25% and 75.54%, respectively. In the equilibrium isotherm study, the adsorption data fitted well with the Langmuir isotherm model. The adsorption kinetics was best depicted by the pseudo-second order model. Desorption experiments showed adsorbent can be reused successfully for three adsorption-desorption cycles. PMID:25815470

Removal of Malachite Green Dye by Mangifera indica Seed Kernel Powder

NASA Astrophysics Data System (ADS)

Singh, Dilbagh; Sowmya, V.; Abinandan, S.; Shanthakumar, S.

2017-11-01

In this study, batch experiments were carried out to study the adsorption of Malachite green dye from aqueous solution by Mangifera indica (mango) seed kernel powder. The mango seed kernel powder was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Effect of various parameters including pH, contact time, adsorbent dosage, initial dye concentration and temperature on adsorption capacity of the adsorbent was observed and the optimized condition for maximum dye removal was identified. Maximum percentage removal of 96% was achieved with an adsorption capacity of 22.8 mg/g at pH 6 with an initial concentration of 100 mg/l. The equilibrium data were examined to fit the Langmuir and Freundlich isotherm models. Thermodynamic parameters for the adsorption process were also calculated.

[Role of calcium ions in the mechanism of action of acetylcholine on energy metabolism in rat liver mitochondria].

PubMed

Vatamaniuk, M Z; Artym, V V; Kuka, O B; Doliba, M M; Shostakovs'ka, I V

1996-01-01

It is shown that administration of acetylcholine to animals (50 micrograms per 100 g of body weight) leads to the activation of respiration and oxidative phosphorylation in the rat liver mitochondria under oxidation of alpha-ketoglutarate; this effect depends on the concentration of calcium ions in the incubation medium of mitochondria. The rate of ADP-stimulated respiration of mitochondria of experimental animals reaches its maximum level under lower concentrations of Ca2+ than in the control animals. The results of investigation of dependence of acetyl choline effect on respiration of mitochondria on the concentration of alpha-ketoglutarate in calcium and calcium-free incubation medium have shown that the half-maximum effect of acetylcholine is observed in calcium medium at lower concentration of the substrate than in calcium-free medium. The latter indicates to the increase of affinity of alpha-ketoglutarate dehydrogenase to alpha-ketoglutarate under these conditions. It is found out that acetylcholine (1.10(-8) M) increases the rate of ADP- and Ca(2+)-stimulated respiration of mitochondria of isolated perfused rat liver, while mutual effect of verapamyl and niphedipin removes this effect.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2015-01-01

The purging operations for cryogenic main propulsion systems of upper stage are usually carried out for the following cases: 1) Purging of the Fill/Drain line after completion of propellant loading. This operation allows the removal of residual propellant mass; and 2) Purging of the Feed/Drain line if the mission is scrubbed. The lines would be purged by connections to a ground high-pressure gas storage source. The flow-rate of purge gas should be regulated such that the pressure in the line will not exceed the required maximum allowable value. Exceeding the maximum allowable pressure may lead to structural damage in the line. To gain confidence in analytical models of the purge process, a test series was conducted. The test article, a 20-cm incline line, was filled with liquid hydrogen and then purged with gaseous helium (GHe). The influences of GHe flow-rates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program, an in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the testing. The test procedures, modeling descriptions, and the results will be presented in the final paper.

Removal of hydrogen sulfide from hot fuel gas using an electrochemical membrane system

NASA Astrophysics Data System (ADS)

Burke, Adrian Alan

Sulfur is a natural contaminant in nearly all fossil fuel supplies. When a fuel stream is gasified or reformed, the sulfur manifests itself in the form of hydrogen sulfide, H2S. Extraordinary effort is put forth to remove H2S to at least ppm levels before the fuel can be used for power generation. To compete with current methods, an electrochemical membrane system (EMS) is now being studied to remove H2S in one step at high temperature. This process offers continuous H2S removal at an estimated operating cost of $0.32/kg H2S removed and a capital cost that is roughly half that of a Claus plant with tail-gas clean-up. Other advantages are the considerable savings in energy and space compared to current methods. A bench scale set-up was constructed to test the cell performance at 600-700°C and 1 atm. The typical fuel stream inlet proportions were 34% CO, 22% CO2, 35% H2, 8% H2O, and 450-2000 ppm H2S. The fundamental transport restrictions for sulfur species in an electrochemical cell were examined. Temperature and membrane thickness were varied to examine how these parameters affect the maximum flux of H 2S removal. It was found that higher temperature allows more sulfide species to enter the electrolyte, thus increasing the sulfide flux across the membrane and raising the maximum flux of H2S removal. Also, membrane thickness was found to be a critical parameter in cell design. A thinner membrane decreases the distance that sulfide ions must travel to be oxidized at the anode. These results identify sulfide diffusion across the membrane as the rate-limiting step in H2S removal. The maximum H2S removal flux of 1.1 x 10-6 gmol H2S min-1 cm-2 (or 3.5 mA cm-2) was obtained at 650°C, with a membrane that was 0.9 mm thick, 36% porous, and had an estimated tortuosity of 3.6. Another focus of this thesis was to examine the stability of cathode materials in full cell trials. A major hurdle that remains in process scale-up is cathode selection, as the lifetime of the cell will depend heavily on the lifetime of the cathode material, which is exposed to very sour gas. Materials that showed success in the past (i.e cobalt sulfides and Y0.9Ca 0.1FeO3) were examined but were seen to have limitations in operating environment and temperature. Therefore, other novel metal oxide compounds were studied to find possible candidates for full cell trials. Gd2TiMoO7 and La0.7Sr0.3VO 3 were the compounds that retained their structure best even when exposed to high H2S, CO2, and H2O concentrations. They also showed no sign of melting at operating temperatures. But Gd 2TiMoO7 was seen to have better stability with electrolyte present, whereas La0.7Sr0.3VO3 was seen to have better stability in the pure sour gas stream without electrolyte present. A layered electrode that could help preserve a stable environment for each of these compounds should be explored in future research.

Effect of famine-phase reduced aeration on polyhydroxyalkanoate accumulation in aerobic granules.

PubMed

Vjayan, T; Vadivelu, V M

2017-12-01

The effects of variable aeration in the famine period on polyhydroxyalkanoate (PHA) accumulation in aerobic granules were investigated. Results showed that regardless of the aeration rates used during famine period, all aerobic granules achieved a similar chemical oxygen demand removal and PHA content. The decrease in famine-period aeration rates accelerated the maximum PHA accumulation together with increase in granular size and settling ability. The PHA-accumulating microorganisms were found to have shifted closer to the surface of the granules when the aeration rate was reduced. Moreover, PHA compositional changes occurred, where the hydroxyvalerate content had increased with the reduction in aeration rate. Ultimately, the results indicate that the requirement of aeration for PHA accumulation in aerobic granules is highly insignificant in the famine phase. PHA production in aerobic granules under zero aeration in the famine period may result in an energy input reduction of up to 74%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Iron fertilisation and century-scale effects of open ocean dissolution of olivine in a simulated CO2 removal experiment

NASA Astrophysics Data System (ADS)

Hauck, Judith; Köhler, Peter; Wolf-Gladrow, Dieter; Völker, Christoph

2016-02-01

Carbon dioxide removal (CDR) approaches are efforts to reduce the atmospheric CO2 concentration. Here we use a marine carbon cycle model to investigate the effects of one CDR technique: the open ocean dissolution of the iron-containing mineral olivine. We analyse the maximum CDR potential of an annual dissolution of 3 Pg olivine during the 21st century and focus on the role of the micro-nutrient iron for the biological carbon pump. Distributing the products of olivine dissolution (bicarbonate, silicic acid, iron) uniformly in the global surface ocean has a maximum CDR potential of 0.57 gC/g-olivine mainly due to the alkalinisation of the ocean, with a significant contribution from the fertilisation of phytoplankton with silicic acid and iron. The part of the CDR caused by ocean fertilisation is not permanent, while the CO2 sequestered by alkalinisation would be stored in the ocean as long as alkalinity is not removed from the system. For high CO2 emission scenarios the CDR potential due to the alkalinity input becomes more efficient over time with increasing ocean acidification. The alkalinity-induced CDR potential scales linearly with the amount of olivine, while the iron-induced CDR saturates at 113 PgC per century (on average ˜ 1.1 PgC yr-1) for an iron input rate of 2.3 Tg Fe yr-1 (1% of the iron contained in 3 Pg olivine). The additional iron-related CO2 uptake occurs in the Southern Ocean and in the iron-limited regions of the Pacific. Effects of this approach on surface ocean pH are small (\\lt 0.01).

Methane production from a field-scale biofilter designed for desulfurization of biogas stream.

PubMed

Pirolli, Mateus; da Silva, Márcio Luís Busi; Mezzari, Melissa Paola; Michelon, William; Prandini, Jean Michel; Moreira Soares, Hugo

2016-07-15

The development of a simple and low maintenance field-scale biotrickling filter (BTF) for desulfurization of swine wastewater-derived biogas stream that was also capable of increasing biomethane concentrations was investigated. BTF was continuously fed with wastewater effluent from an air sparged nitrification-denitrification bioreactor installed downgradient from an UASB-type digester. BTF maximum removal efficiency (RE) of 99.8% was achieved with a maximum elimination capacity (EC) of 1,509 g H2S m(-3) h(-1). Average EC obtained with inlet biogas flow rates of 0.024, 0.036 and 0.048 m(3) h(-1) was 718, 1,013 and 438 g H2S m(-3) h(-1), respectively. SO4(-2) and S(0) were the major metabolites produced from biological conversion of H2S. Additionally to the satisfactory biodesulfurization capacity, an average increase in methane concentration of ≅ 3.8 ± 1.68 g m(-3) was measured in the filtered gas stream throughout 200 days of BTF operation. RT-PCR analyses of archaea communities in the biofilm confirmed dominance of hydrogenotrophic methanogens thus corroborating with the observed strong correlation between CO2 removal and CH4 production. Among the three major archaea orders investigated (i.e., Methanosarcinales, Methanobacteriales, and Methanomicrobiales), Methanobacteriales were encountered at highest concentrations (1.9 × 10(11) gene copies mL(-1)). The proposed BTF was robust efficiently removing H2S from biogas stream while concomitantly enhancing the concentration of valuable methane as source of renewable fuel. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anammox enrichment from reject water on blank biofilm carriers and carriers containing nitrifying biomass: operation of two moving bed biofilm reactors (MBBR).

PubMed

Zekker, Ivar; Rikmann, Ergo; Tenno, Toomas; Lemmiksoo, Vallo; Menert, Anne; Loorits, Liis; Vabamäe, Priit; Tomingas, Martin; Tenno, Taavo

2012-07-01

The anammox bacteria were enriched from reject water of anaerobic digestion of municipal wastewater sludge onto moving bed biofilm reactor (MBBR) system carriers-the ones initially containing no biomass (MBBR1) as well as the ones containing nitrifying biomass (MBBR2). Duration of start-up periods of the both reactors was similar (about 100 days), but stable total nitrogen (TN) removal efficiency occurred earlier in the system containing nitrifying biomass. Anammox TN removal efficiency of 70% was achieved by 180 days in both 20 l volume reactors at moderate temperature of 26.0°C. During the steady state phase of operation of MBBRs the average TN removal efficiencies and maximum TN removal rates in MBBR1 were 80% (1,000 g-N/m(3)/day, achieved by 308 days) and in MBBR2 85% (1,100 g-N/m(3)/day, achieved by 266 days). In both reactors mixed bacterial cultures were detected. Uncultured Planctomycetales bacterium clone P4, Candidatus Nitrospira defluvii and uncultured Nitrospira sp. clone 53 were identified by PCR-DGGE from the system initially containing blank biofilm carriers as well as from the nitrifying biofilm system; from the latter in addition to these also uncultured ammonium oxidizing bacterium clone W1 and Nitrospira sp. clone S1-62 were detected. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. Using previously grown nitrifying biofilm matrix for anammox enrichment has some benefits over starting up the process from zero, such as less time for enrichment and protection against severe inhibitions in case of high substrate loading rates.

Performance evaluation of a slow-release packing material-embedded functional microorganisms for biofiltration.

PubMed

Zhu, Rencheng; Li, Shunyi; Wu, Zhenjun; Dumont, Éric

2017-04-01

A composite packing material (CM-5) was prepared in this study, mainly consisting of compost with functional microorganisms, calcium carbonate (CaCO 3 ), perlite, cement and plant fiber. To get stronger compressive strength, mass ratios of these components were optimized based on single factor experiments, and finally adding amounts of perlite, cement, plant fiber, CaCO 3 , compost and binder at 18%, 18%, 7%, 13%, 17% and 27%, respectively. According to the optimum proportion, CM-5 was extruded in cylindrical shape (12 mm in diameter and 20 mm in length) with a bulk density of 470 kg m -3 , a moisture retention capacity of 49% and the microbial counts of × 10 5 CFU g -1 of packing material. The cumulative release rates of total organic carbon (TOC) and total nitrogen (TN) from CM-5 were 3.1% and 6.5%, respectively, after 19 times extraction in distilled water. To evaluate the H 2 S removal capacity, CM-5 was compared with an organic (corncob) and an inorganic (ceramsite) packing material in three biofilters. The results showed that CM-5 had higher H 2 S removal capacity compared with corncob and ceramsite. CM-5 could avoid the large fluctuation of pH value and pressure drop during the operation. The maximum H 2 S removal capacity of CM-5 was 12.9 g m -3  h -1 and the removal efficiency could maintain over 95.4% when the inlet H 2 S loading rate was lower than 11.3 g m -3  h -1 without any addition of nutrients and pH buffer substances. Besides, only 2-3 days were needed for the recovery of biofiltration performance after about two weeks of idle period.

Biodegradable polymer based ternary blends for removal of trace metals from simulated industrial wastewater.

PubMed

Prakash, N; Arungalai Vendan, S

2016-02-01

The ternary blends consisting of Chitosan (CS), Nylon 6 (Ny 6) and Montmorillonite clay (MM clay) were prepared by the solution blending method with glutaraldehyde. The prepared ternary blends were characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermo gravimetric analysis (TGA), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). The FTIR results showed that the strong intermolecular hydrogen bondings were established between chitosan, nylon 6 and montmorillonite clay. TGA showed the thermal stability of the blend is enhanced by glutaraldehyde as Crosslink agent. Results of XRD indicated that the relative crystalline of the pure chitosan film was reduced when the polymeric network was reticulated by glutaraldehyde. Finally, the results of scanning electron microscopy (SEM) indicated that the morphology of the blend was rough and heterogenous. Further, it confirms the interaction between the functional groups of the blend components. The extent of removal of the trace metals was found to be almost the same. The removal of these metals at different pH was also done and the maximum removal of the metals was observed at pH 4.5 for both trace metals. Adsorption studies and kinetic analysis have also been made. Moreover, the protonation of amine groups is induced an electrostatic repulsion of cations. When the pH of the solution was more than 5.5, the sorption rate began to decrease. Besides, the quantity of adsorbate on absorbent was fitted as a function in Langmuir and Freundlich isotherm. The sorption kinetics was tested for pseudo first order and pseudo second order reaction. The kinetic experimental data correlated with the second order kinetic model and rate constants of sorption for kinetic models were calculated and accordingly, the correlation coefficients were obtained. Copyright © 2016. Published by Elsevier B.V.

Orbital Atherectomy Plaque Modification Assessment of the Femoropopliteal Artery Via Intravascular Ultrasound (TRUTH Study)

PubMed Central

Zavlunova, Susanna; Attubato, Michael J.; Martinsen, Brad J.; Mintz, Gary S.; Maehara, Akiko

2015-01-01

Objective: The Tissue Removal Assessment with Ultrasound of the SFA and Popliteal (TRUTH) study assessed the performance of the orbital atherectomy system (OAS) to treat femoropopliteal arteries, including determining its effect on plaque removal. Methods: Patients with symptomatic femoropopliteal peripheral arterial disease were treated with the OAS followed by adjunctive balloon angioplasty (BA). Intravascular ultrasound (IVUS) images were collected pre- and post-OAS and post-OAS BA. Patients were followed through 12 months post-procedure. Results: Twenty-nine lesions were treated with OAS-BA in 25 patients. The mean maximum balloon inflation pressure was 5.2 ± 1.2 atm. Virtual histology IVUS (VH-IVUS) analysis revealed at the maximum calcium ablation site that calcium reduction was responsible for 86% of the lumen area increase. The minimum lumen area increased from 4.0 mm2 to 9.1 mm2 (<.0001), and the percentage of area stenosis decreased from 76.9% to 43.0% (<.0001) after OAS-BA. At 12 months, the target lesion revascularization rate was 8.2%, and ankle–brachial index and Rutherford classification improved significantly from baseline through follow-up. Conclusion: The VH-IVUS analysis reveals that OAS modifies the calcified component of the plaque burden. It is hypothesized that calcium modification by OAS changes the lesion compliance, allowing for low pressure adjunctive BA. The clinical outcomes were favorable through 12-month follow-up. PMID:26490645

Orbital Atherectomy Plaque Modification Assessment of the Femoropopliteal Artery Via Intravascular Ultrasound (TRUTH Study).

PubMed

Babaev, Anvar; Zavlunova, Susanna; Attubato, Michael J; Martinsen, Brad J; Mintz, Gary S; Maehara, Akiko

2015-10-01

The Tissue Removal Assessment with Ultrasound of the SFA and Popliteal (TRUTH) study assessed the performance of the orbital atherectomy system (OAS) to treat femoropopliteal arteries, including determining its effect on plaque removal. Patients with symptomatic femoropopliteal peripheral arterial disease were treated with the OAS followed by adjunctive balloon angioplasty (BA). Intravascular ultrasound (IVUS) images were collected pre- and post-OAS and post-OAS BA. Patients were followed through 12 months post-procedure. Twenty-nine lesions were treated with OAS-BA in 25 patients. The mean maximum balloon inflation pressure was 5.2 ± 1.2 atm. Virtual histology IVUS (VH-IVUS) analysis revealed at the maximum calcium ablation site that calcium reduction was responsible for 86% of the lumen area increase. The minimum lumen area increased from 4.0 mm(2) to 9.1 mm(2) (<.0001), and the percentage of area stenosis decreased from 76.9% to 43.0% (<.0001) after OAS-BA. At 12 months, the target lesion revascularization rate was 8.2%, and ankle-brachial index and Rutherford classification improved significantly from baseline through follow-up. The VH-IVUS analysis reveals that OAS modifies the calcified component of the plaque burden. It is hypothesized that calcium modification by OAS changes the lesion compliance, allowing for low pressure adjunctive BA. The clinical outcomes were favorable through 12-month follow-up. © The Author(s) 2015.

Feasibility of constructed wetland planted with Leersia hexandra Swartz for removing Cr, Cu and Ni from electroplating wastewater.

PubMed

You, Shao-Hong; Zhang, Xue-Hong; Liu, Jie; Zhu, Yi-Nian; Gu, Chen

2014-01-01

As a low-cost treatment technology for effluent, the constructed wetlands can be applied to remove the heavy metals from wastewater. Leersia hexandra Swartz is a metal-accumulating hygrophyte with great potential to remove heavy metal from water. In this study, two pilot-scale constructed wetlands planted with L. hexandra (CWL) were set up in greenhouse to treat electroplating wastewater containing Cr, Cu and Ni. The treatment performance of CWL under different hydraulic loading rates (HLR) and initial metal concentrations were also evaluated. The results showed that CWL significantly reduced the concentrations of Cr, Cu and Ni in wastewater by 84.4%, 97.1% and 94.3%, respectively. High HLR decreased the removal efficiencies of Cr, Cu and Ni; however, the heavy metal concentrations in effluent met Emission Standard of Pollutants for Electroplating in China (ESPE) at HLR less than 0.3 m3/m2 d. For the influent of 5 mg/L Cr, 10 mg/L Cu and 8 mg/L Ni, effluent concentrations were below maximum allowable concentrations in ESPE, indicating that the removal of Cr, Cu and Ni by CWL was feasible at considerably high influent metal concentrations. Mass balance showed that the primary sink for the retention of contaminants within the constructed wetland system was the sediment, which accounted for 59.5%, 83.5%, and 73.9% of the Cr, Cu and Ni, respectively. The data from the pilot wetlands support the view that CWL could be used to successfully remove Cr, Cu and Ni from electroplating wastewater.

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.

Trivalent chromium removal from wastewater using low cost activated carbon derived from agricultural waste material and activated carbon fabric cloth.

PubMed

Mohan, Dinesh; Singh, Kunwar P; Singh, Vinod K

2006-07-31

An efficient adsorption process is developed for the decontamination of trivalent chromium from tannery effluents. A low cost activated carbon (ATFAC) was prepared from coconut shell fibers (an agricultural waste), characterized and utilized for Cr(III) removal from water/wastewater. A commercially available activated carbon fabric cloth (ACF) was also studied for comparative evaluation. All the equilibrium and kinetic studies were conducted at different temperatures, particle size, pHs, and adsorbent doses in batch mode. The Langmuir and Freundlich isotherm models were applied. The Langmuir model best fit the equilibrium isotherm data. The maximum adsorption capacities of ATFAC and ACF at 25 degrees C are 12.2 and 39.56 mg/g, respectively. Cr(III) adsorption increased with an increase in temperature (10 degrees C: ATFAC--10.97 mg/g, ACF--36.05 mg/g; 40 degrees C: ATFAC--16.10 mg/g, ACF--40.29 mg/g). The kinetic studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent, and solid to liquid ratio. The adsorption of Cr(III) follows the pseudo-second-order rate kinetics. From kinetic studies various rate and thermodynamic parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated. The sorption capacity of activated carbon (ATFAC) and activated carbon fabric cloth is comparable to many other adsorbents/carbons/biosorbents utilized for the removal of trivalent chromium from water/wastewater.

Aerobic biological treatment of synthetic municipal wastewater in membrane-coupled bioreactors.

PubMed

Klatt, Christian G; LaPara, Timothy M

2003-05-05

Membrane-coupled bioreactors (MBRs) offer many benefits compared to conventional biological wastewater treatment systems; however, their performance characteristics are poorly understood. Laboratory-scale MBRs were used to study bacterial adaptations in physiology and community structure. MBRs were fed a mixture of starch, gelatin, and polyoxyethylene-sorbitan monooleate to simulate the polysaccharide, protein, and lipid components of municipal wastewater. Physiological adaptations were detected by measuring ectoenzyme activity while structural dynamics were studied by denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments. As cell biomass accumulated in the MBRs, pollutant removal efficiency initially improved and then stabilized with respect to effluent concentrations of chemical oxygen demand, protein, and carbohydrate. Comparison of the MBR effluent to filtered reactor fluid indicated that a portion of the observed pollutant removal was due to filtration by the membrane rather than microbial activity. The rates of ectoenzyme-mediated polysaccharide (alpha-glucosidase) and protein (leucine aminopeptidase) hydrolysis became relatively constant once pollutant removal efficiency stabilized. However, the maximum rate of lipid hydrolysis (heptanoate esterase) concomitantly increased more than 10-fold. Similarly, alpha-glucosidase and leucine aminopeptidase ectoenzyme affinities were relatively constant, while the heptanoate esterase affinity increased more than 30-fold. Community analysis revealed that a substantial community shift occurred within the first 7 days of operation. A Flavobacterium-like bacterial population dominated the community (>50% of total band intensity) and continued to do so for the remainder of the experiment. Copyright 2003 Wiley Periodicals, Inc.

Cometabolic degradation of ethyl mercaptan by phenol-utilizing Ralstonia eutropha in suspended growth and gas-recycling trickle-bed reactor.

PubMed

Sedighi, Mahsa; Zamir, Seyed Morteza; Vahabzadeh, Farzaneh

2016-01-01

The degradability of ethyl mercaptan (EM), by phenol-utilizing cells of Ralstonia eutropha, in both suspended and immobilized culture systems, was investigated in the present study. Free-cells experiments conducted at EM concentrations ranging from 1.25 to 14.42 mg/l, showed almost complete removal of EM at concentrations below 10.08 mg/l, which is much higher than the maximum biodegradable EM concentration obtained in experiments that did not utilize phenol as the primary substrate, i.e. 2.5 mg/l. The first-order kinetic rate constant (kSKS) for EM biodegradation by the phenol-utilizing cells (1.7 l/g biomass/h) was about 10 times higher than by cells without phenol utilization. Immobilized-cells experiments performed in a gas recycling trickle-bed reactor packed with kissiris particles at EM concentrations ranging from 1.6 to 36.9 mg/l, showed complete removal at all tested concentrations in a much shorter time, compared with free cells. The first-order kinetic rate constant (rmaxKs) for EM utilization was 0.04 l/h for the immobilized system compared to 0.06 for the suspended-growth culture, due to external mass transfer diffusion. Diffusion limitation was decreased by increasing the recycling-liquid flow rate from 25 to 65 ml/min. The removed EM was almost completely mineralized according to TOC and sulfate measurements. Shut down and starvation experiments revealed that the reactor could effectively handle the starving conditions and was reliable for full-scale application. Copyright © 2015 Elsevier Ltd. All rights reserved.

Increased diazinon hydrolysis to 2-isopropyl-6-methyl-4-pyrimidinol in liquid medium by a specific Streptomyces mixed culture.

PubMed

Briceño, G; Schalchli, H; Rubilar, O; Tortella, G R; Mutis, A; Benimeli, C S; Palma, G; Diez, M C

2016-08-01

Actinobacteria identified as Streptomyces spp. were evaluated for their ability to remove diazinon as the only carbon source from a liquid medium. Single cultures of Streptomyces strains were exposed to diazinon at a concentration of 50 mg L(-1). After 96 h incubation, six of the eight cultures grew and five strains showed an increase in their total protein concentrations and changes in their protein profile. Up to 32% of the diazinon was removed by the single Streptomyces cultures. A compatibility assay showed that the different Streptomyces species were not antagonistic. Twenty-six mixed cultures were then prepared. Diazinon removal was increased when mixed cultures were used, and maximum diazinon removal of 62% was observed when the Streptomyces spp. strains AC5, AC9, GA11 and ISP13 were mixed; this was defined as the selected mixed culture (SMC). Diazinon removal was positively influenced by the addition of glucose into the liquid medium. Our study showed a diazinon degradation rate of 0.025 h(-1), half-life of 28 h(-1) and 2-isopropyl-6-methyl-4-pyrimidinol (IMHP) production of 0.143 mg L h(-1). Rapid diazinon hydrolysis to IMHP was associated with a decrease in the pH of the medium as a consequence of microbial glucose metabolism and organic acid exudation. Moreover, the SMC of Streptomyces was able to remove IMHP. This work constitutes a new, if not the only, report on diazinon degradation by mixed cultures of Streptomyces spp. Given the high levels of diazinon removal, the SMC formed by four Streptomyces strains has the potential to be used to treat the diazinon present in environmental matrices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of industrial dyes and heavy metals by Beauveria bassiana: FTIR, SEM, TEM and AFM investigations with Pb(II).

PubMed

Gola, Deepak; Malik, Anushree; Namburath, Maneesh; Ahammad, Shaikh Ziauddin

2017-10-01

Presence of industrial dyes and heavy metal as a contaminant in environment poses a great risk to human health. In order to develop a potential technology for remediation of dyes (Reactive remazol red, Yellow 3RS, Indanthrene blue and Vat novatic grey) and heavy metal [Cu(II), Ni(II), Cd(II), Zn(II), Cr(VI) and Pb(II)] contamination, present study was performed with entomopathogenic fungi, Beauveria bassiana (MTCC no. 4580). High dye removal (88-97%) was observed during the growth of B. bassiana while removal percentage for heavy metals ranged from 58 to 75%. Further, detailed investigations were performed with Pb(II) in terms of growth kinetics, effect of process parameters and mechanism of removal. Growth rate decreased from 0.118 h -1 (control) to 0.031 h -1 , showing 28% reduction in biomass at 30 mg L -1 Pb(II) with 58.4% metal removal. Maximum Pb(II) removal was observed at 30 °C, neutral pH and 30 mg L -1 initial metal concentration. FTIR analysis indicated the changes induced by Pb(II) in functional groups on biomass surface. Further, microscopic analysis (SEM and atomic force microscopy (AFM)) was performed to understand the changes in cell surface morphology of the fungal cell. SEM micrograph showed a clear deformation of fungal hyphae, whereas AFM studies proved the increase in surface roughness (RSM) in comparison to control cell. Homogenous bioaccumulation of Pb(II) inside the fungal cell was clearly depicted by TEM-high-angle annular dark field coupled with EDX. Present study provides an insight into the mechanism of Pb(II) bioremediation and strengthens the significance of using entomopathogenic fungus such as B. bassiana for metal and dye removal.

Analysis of enamel surface damage after selective laser ablation of composite from tooth surfaces.

PubMed

Chan, Kenneth H; Hirasuna, Krista; Fried, Daniel

2014-02-01

Resin-based composites are used for many applications in dentistry. They are difficult to remove without damage to the underlying enamel since they adhere strongly and are color matched to the tooth. The objective of this study was to determine if an automated laser scanning system with spectral feedback could be used for selective removal of residual orthodontic composite from tooth surfaces with minimal damage to the underlying enamel. A CO 2 laser operating at a wavelength of 9.3 μm with a pulse duration of 10-15 μs and a pulse repetition rate of ~200 Hz was used to selectively remove composite from the buccal surfaces of extracted teeth. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Conventional and digital microscopes were used to assess the amount of enamel lost during removal. The amount of enamel lost averaged between 20 and 25 μm for irradiation intensities from 3.8 to 4.2 J/cm 2 , respectively. An average maximum temperature rise of 1.9±1.5°C was recorded, with no teeth approaching the critical value of 5.5°C. The average time for composite removal from an area of 5 mm 2 was 19.3±4.1 s, fast enough for clinical feasibility. Residual composite can be rapidly removed from tooth surfaces using a CO 2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal loss of sound enamel.

Sustainable operation of submerged Anammox membrane bioreactor with recycling biogas sparging for alleviating membrane fouling.

PubMed

Li, Ziyin; Xu, Xindi; Xu, Xiaochen; Yang, FengLin; Zhang, ShuShen

2015-12-01

A submerged anaerobic ammonium oxidizing (Anammox) membrane bioreactor with recycling biogas sparging for alleviating membrane fouling has been successfully operated for 100d. Based on the batch tests, a recycling biogas sparging rate at 0.2m(3)h(-1) was fixed as an ultimate value for the sustainable operation. The mixed liquor volatile suspended solid (VSS) of the inoculum for the long operation was around 3000mgL(-1). With recycling biogas sparging rate increasing stepwise from 0 to 0.2m(3)h(-1), the reactor reached an influent total nitrogen (TN) up to 1.7gL(-1), a stable TN removal efficiency of 83% and a maximum specific Anammox activity (SAA) of 0.56kg TNkg(-1) VSSd(-1). With recycling biogas sparging rate at 0.2 m(3) h(-1) (corresponding to an aeration intensity of 118m(3)m(-2)h(-1)), the membrane operation circle could prolong by around 20 times compared to that without gas sparging. Furthermore, mechanism of membrane fouling was proposed. And with recycling biogas sparging, the VSS and EPS content increasing rate in cake layer were far less than the ones without biogas sparging. The TN removal performance and sustainable membrane operation of this system showed the appealing potential of the submerged Anammox MBR with recycling biogas sparging in treating high-strength nitrogen-containing wastewaters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Research on disposal of copper(II)-containing wastewater by secondary strontium residue

NASA Astrophysics Data System (ADS)

Qing, Duowen; Xu, Longjun; Cui, Caixi

2018-01-01

Secondary strontium residue (SSR) was used as absorbent to remove Cu2+ in solution and the effects of experimental conditions on absorption of Cu2+ were investigated. The results showed that the absorption process reached balance in around 40 min. The absorption capacity achieved the maximum when PH value reached 6, and the maximum adsorption of Cu2+-containing wastewater by secondary strontium residue was 5.46 mg/g. Removal ratio of Cu2+ was in relation to initial concentration of Cu2+ in solution. Adsorptive process tallied with Langmuir Isothermal adsorption model.

Kinetic and equilibrium studies on the removal of Cd2+ ions from water using polyacrylamide grafted rice (Oryza sativa) husk and (Tectona grandis) saw dust.

PubMed

Sharma, Neeta; Kaur, Kulwinder; Kaur, Sumanjit

2009-04-30

The increase in the use of heavy metals has resulted in an increased flux of metallic substances into the aquatic environment which poses a danger to human health. The present work relates to the removal of cadmium ions by treatment with polyacrylamide grafted rice (Oryza sativa) husk/saguan (Tectona grandis) saw dust. The drinking water guideline value recommended by WHO for cadmium is 0.005 ppm.The adsorbent has been prepared by treatment of rice husk/saw dust with acrylamide. Removal has been studied at various pH values for different times of contact and adsorbate concentrations and is found to be pH-dependent, maximum removal occurs at pH 9 and at a contact time of 180 min for both the adsorbents. The results were found to be consistent with both the Langmuir and Freundlich isotherm models. The value of n (rate constant) determined at pH 9 has been found to be 1 (within experimental limits). This is further substantiated by applying the Lagergren model. The intra-particle diffusion constants were determined by the Morris-Weber model. Continuous flow column studies have also been undertaken and the breakthrough characteristics were determined. Desorption has been affected with 0.5M HCl. The results suggest that both polyacrylamide grafted rice husk/saw dust can be used as efficient and cost effective adsorbents for cadmium ion removal.

Nitrogen removal in maturation waste stabilisation ponds via biological uptake and sedimentation of dead biomass.

PubMed

Camargo Valero, M A; Mara, D D; Newton, R J

2010-01-01

In this work a set of experiments was undertaken in a pilot-scale WSP system to determine the importance of organic nitrogen sedimentation on ammonium and total nitrogen removals in maturation ponds and its seasonal variation under British weather conditions, from September 2004 to May 2007. The nitrogen content in collected sediment samples varied from 4.17% to 6.78% (dry weight) and calculated nitrogen sedimentation rates ranged from 273 to 2868 g N/ha d. High ammonium removals were observed together with high concentrations of chlorophyll-a in the pond effluent. Moreover, chlorophyll-a had a very good correlation with the corresponding increment of VSS (algal biomass) and suspended organic nitrogen (biological nitrogen uptake) in the maturation pond effluents. Therefore, when ammonium removal reached its maximum, total nitrogen removal was very poor as most of the ammonia taken up by algae was washed out in the pond effluent in the form of suspended solids. After sedimentation of the dead algal biomass, it was clear that algal-cell nitrogen was recycled from the sludge layer into the pond water column. Recycled nitrogen can either be taken up by algae or washed out in the pond effluent. Biological (mainly algal) uptake of inorganic nitrogen species and further sedimentation of dead biomass (together with its subsequent mineralization) is one of the major mechanisms controlling in-pond nitrogen recycling in maturation WSP, particularly when environmental and operational conditions are favourable for algal growth.

Application of Box-Wilson experimental design method for 2,4-dinitrotoluene treatment in a sequential anaerobic migrating blanket reactor (AMBR)/aerobic completely stirred tank reactor (CSTR) system.

PubMed

Kuşçu, Özlem Selçuk; Sponza, Delia Teresa

2011-03-15

A sequential aerobic completely stirred tank reactor (CSTR) following the anaerobic migrating blanket reactor (AMBR) was used to treat a synthetic wastewater containing 2,4-dinitrotoluene (2,4-DNT). A Box-Wilson statistical experiment design was used to determine the effects of 2,4-DNT and the hydraulic retention times (HRTs) on 2,4-DNT and COD removal efficiencies in the AMBR reactor. The 2,4-DNT concentrations in the feed (0-280 mg/L) and the HRT (0.5-10 days) were considered as the independent variables while the 2,4-DNT and chemical oxygen demand (COD) removal efficiencies, total and methane gas productions, methane gas percentage, pH, total volatile fatty acid (TVFA) and total volatile fatty acid/bicarbonate alkalinity (TVFA/Bic.Alk.) ratio were considered as the objective functions in the Box-Wilson statistical experiment design in the AMBR. The predicted data for the parameters given above were determined from the response functions by regression analysis of the experimental data and exhibited excellent agreement with the experimental results. The optimum HRT which gave the maximum COD (97.00%) and 2,4-DNT removal (99.90%) efficiencies was between 5 and 10 days at influent 2,4-DNT concentrations 1-280 mg/L in the AMBR. The aerobic CSTR was used for removals of residual COD remaining from the AMBR, and for metabolites of 2,4-DNT. The maximum COD removal efficiency was 99% at an HRT of 1.89 days at a 2,4-DNT concentration of 239 mg/L in the aerobic CSTR. It was found that 280 mg/L 2,4-DNT transformed to 2,4-diaminotoluene (2,4-DAT) via 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) in the AMBR. The maximum 2,4-DAT removal was 82% at an HRT of 8.61 days in the aerobic CSTR. The maximum total COD and 2,4-DNT removal efficiencies were 99.00% and 99.99%, respectively, at an influent 2,4-DNT concentration of 239 mg/L and at 1.89 days of HRT in the sequential AMBR/CSTR. Copyright © 2011 Elsevier B.V. All rights reserved.

TRICARE; Revision of Nonparticipating Providers Reimbursement Rate; Removal of Cost Share for Dental Sealants; TRICARE Dental Program. Final rule.

PubMed

2016-03-07

This final rule revises the benefit payment provision for nonparticipating providers to more closely mirror industry practices by requiring TDP nonparticipating providers to be reimbursed (minus the appropriate cost-share) at the lesser of billed charges or the network maximum allowable charge for similar services in that same locality (region) or state. This rule also updates the regulatory provisions regarding dental sealants to clearly categorize them as a preventive service and, consequently, eliminate the current 20 percent cost-share applicable to sealants to conform with the language in the regulation to the statute.

Study on industrial wastewater treatment using superconducting magnetic separation

NASA Astrophysics Data System (ADS)

Zhang, Hao; Zhao, Zhengquan; Xu, Xiangdong; Li, Laifeng

2011-06-01

The mechanism of industrial wastewater treatment using superconducting magnetic separation is investigated. Fe 3O 4 nanoparticles were prepared by liquid precipitation and characterized by X-ray diffraction (XRD). Polyacrylic acid (PAA) film was coated on the magnetic particles using plasma coating technique. Transmission electron microscope (TEM) observation and infrared spectrum measurement indicate that the particle surface is well coated with PAA, and the film thickness is around 1 nm. Practical paper factory wastewater treatment using the modified magnetic seeds in a superconducting magnet (SCM) was carried out. The results show that the maximum removal rate of chemical oxygen demand (COD) by SCM method can reach 76%.

Photocatalytic degradation of furfural in aqueous solution by N-doped titanium dioxide nanoparticles.

PubMed

Veisi, Farzaneh; Zazouli, Mohammad Ali; Ebrahimzadeh, Mohammad Ali; Charati, Jamshid Yazdani; Dezfoli, Amin Shiralizadeh

2016-11-01

The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO 2 /Sun and N-TiO 2 /UV) in a lab-scale batch photoreactor. The N-TiO 2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO 2 /UV and N-TiO 2 /Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO 2 /UV process was higher than that using the N-TiO 2 /Sun process.

Biosorption of clofibric acid and carbamazepine in aqueous solution by agricultural waste rice straw.

PubMed

Liu, Zhanguang; Zhou, Xuefei; Chen, Xiaohua; Dai, Chaomeng; Zhang, Juan; Zhang, Yalei

2013-12-01

Due to their widespread use, clofibric acid (CA) and carbamazepine (CBZ) have been frequently detected simultaneously at relatively high concentrations in aquatic environments. In this study, agricultural waste rice straw was employed as a potentially low-cost, effective and easy-to-operate biosorbent (RSB) to remove CA and CBZ. The adsorption of both pharmaceuticals followed pseudo second-order kinetics, and intraparticle diffusion was an important rate-limiting step. The adsorption isotherms of both drugs were fit well with Freundlich model. The adsorption of CA onto RSB was exothermic and was more likely to be dominated by physical processes, while the adsorption of CBZ was endothermic. Solution pH was determined to be the most important factor for CA adsorption, such that the adsorption capacity of CA onto RSB increased with the decline of solution pH. In the lower range of solution pH below 3.1, the CA removal efficiency was enhanced with the increase of biosorbent dosage. The CBZ removal efficiency was enhanced with the increase of RSB dosage without pH control. The maximum adsorption capacities were 126.3 mg/g for CA and 40.0 mg/g for CBZ.

Removal of chromium (VI) using poly(methylacrylate) functionalized guar gum.

PubMed

Singh, Vandana; Kumari, Premlata; Pandey, Sadanand; Narayan, Tripti

2009-03-01

Using persulfate/ascorbic acid redox pair, poly(methylacrylate) was grafted on to guar gum and the conditions for the grafting were optimized. The copolymer sample having maximum %G was evaluated for the removal of Cr(VI) and the sorption conditions were optimized. The sorption was found pH dependent, pH 1.0 being the optimum value. Sorption data at pH 1.0 were modeled using both the Langmuir and Freundlich isotherms where the data fitted better to Freundlich isotherm. The equilibrium sorption capacity of 29.67mg/g was determined from the Langmuir isotherm. The sorption followed a pseudo-second-order kinetics with a rate constant 2.5x10(-4)gmg(-1) min(-1). The grafted product was also evaluated for Cr(VI) removal from local electroplating industrial waste water. The regeneration experiments revealed that the guar-graft-poly(methylacrylate) could be successfully reused for five cycles. In the present study conductivity measurements were used instead of conventional photometric method for determining Cr(VI) concentration in the equilibrium solutions and the results obtained have been compared with photometric method. Optimum Cr(VI) binding under highly acidic conditions indicated significant contribution of non electrostatic forces in the adsorption process.

Estimation of septic tank setback distances based on transport of E. coli and F-RNA phages.

PubMed

Pang, Liping; Close, Murray; Goltz, Mark; Sinton, Lester; Davies, Helen; Hall, Carollyn; Stanton, Greg

2004-01-01

Setback distances between septic tank systems and the shorelines of Lake Okareka, New Zealand were determined from model simulations for a worst-case scenario, using the highest hydraulic conductivity and gradient measured in the field, removal rates of the microbial indicators (Escherichia coli and F-RNA phages) determined from a column experiment, and maximum values of the design criteria for the disposal system, and assuming an absence of an unsaturated zone, a continuous discharge of the raw effluent from a failed or non-complying treatment system (both indicators at concentrations of 1x10(7) counts/100 ml) into the groundwater and no sorption of pathogens in the aquifer. Modelling results suggest that the minimal setback distances were 16 m to satisfy the New Zealand Recreational Water Quality Guidelines for E. coli <126 per 100 ml (Ministry for the Environment, 1999) and 48 m to meet the Drinking-Water Standards for New Zealand 2000 for enteric virus <1 per 100 l (Ministry of Health, 2000). These distances may be applicable for other lakeshores in pumice sand aquifers with groundwater velocities <7 m/day. Findings of laboratory column and batch experiments provided an insight into the microbial attenuation and transport processes in pumice sand aquifers. Bacterial removal was predominately through filtration (87-88%) and partially by die-off (12-13%), while viral removal was by both die-off (45%) and filtration (55%). In addition, microbial die-off in groundwater without aquifer material (i.e., free microbes) was much lower than die-off in groundwater with aquifer material (i.e., sorbed microbes) and contributed only 2-6% to the total removal. This implies that the setback distances estimated from die-off rates for the free microbes, determined in the laboratory without considering aquifer media and other removal processes, which are often reported in the literature, could be larger than necessary.

Distribution and life strategies of two bacterial populations in a eutrophic lake

PubMed

Weinbauer; Hofle

1998-10-01

Monoclonal antibodies and epifluorescence microscopy were used to determine the depth distribution of two indigenous bacterial populations in the stratified Lake Plusssee and characterize their life strategies. Populations of Comamonas acidovorans PX54 showed a depth distribution with maximum abundances in the oxic epilimnion, whereas Aeromonas hydrophila PU7718 showed a depth distribution with maximum abundances in the anoxic thermocline layer (metalimnion), i. e., in the water layer with the highest microbial activity. Resistance of PX54 to protist grazing and high metabolic versatility and growth rate of PU7718 were the most important life strategy traits for explaining the depth distribution of the two bacterial populations. Maximum abundance of PX54 was 16,000 cells per ml, and maximum abundance of PU7718 was 20,000 cells per ml. Determination of bacterial productivity in dilution cultures with different-size fractions of dissolved organic matter (DOM) from lake water indicates that low-molecular-weight (LMW) DOM is less bioreactive than total DOM (TDOM). The abundance and growth rate of PU7718 were highest in the TDOM fractions, whereas those of PX54 were highest in the LMW DOM fraction, demonstrating that PX54 can grow well on the less bioreactive DOM fraction. We estimated that 13 to 24% of the entire bacterial community and 14% of PU7718 were removed by viral lysis, whereas no significant effect of viral lysis on PX54 could be detected. Growth rates of PX54 (0.11 to 0.13 h-1) were higher than those of the entire bacterial community (0.04 to 0.08 h-1) but lower than those of PU7718 (0.26 to 0.31 h-1). In undiluted cultures, the growth rates were significantly lower, pointing to density effects such as resource limitation or antibiosis, and the effects were stronger for PU7718 and the entire bacterial community than for PX54. Life strategy characterizations based on data from literature and this study revealed that the fast-growing and metabolically versatile A. hydrophila PU7718 is an r-strategist or opportunistic population in Lake Plusssee, whereas the grazing-resistant C. acidovorans PX54 is rather a K-strategist or equilibrium population.

Study of Mo (VI) removal from aqueous solution: application of different mathematical models to continuous biosorption data.

PubMed

Kafshgari, Fatemeh; Keshtkar, Ali Reza; Mousavian, Mohammad Ali

2013-01-25

Molybdenum (VI) biosorption process was investigated by marine algae Cystoseria indica pretreated with 0.1 M CaCl2 solution in a packed bed column. The biosorbent was characterized by FTIR, BET and SEM analyses. The results showed that Mo (VI) ions should be chelated with the hydroxyl, carboxyl and amine groups of the biomass. The effects of inlet metal concentration and flow rate on biosorption process were investigated and the experimental breakthrough curves were obtained. Results showed that the maximum biosorption capacity of Ca-pretreated C. indica for Mo (VI) was found to be 18.32 mg/g at optimum flow rate of (1.4 mL/min). The controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. Also, it was observed that the breakthrough and exhaustion time decreased from 17.14 hr to 9.05 hr and from 0.006 h to 0.002 hr respectively, with the increase of flow rate from 0.7 to 2.1 ML/min. The increase in the initial concentration of Mo (VI) solution from 30 to 95 ml min-1 increases the adsorption capacity from 18.32 to 30.19 mg/g and decreases the percentage of Mo (VI) removal from 61 to 38%. Also, the treated volume was the greatest (1.42 L) at the lowest inlet concentration. Column data obtained under different conditions were described using the Thomas, Yoon and Nelson, Yan and Belter models. The breakthrough curve predictions by Belter model were found to be very satisfactory.

Performance of integrated bioelectrochemical membrane reactor: Energy recovery, pollutant removal and membrane fouling alleviation

NASA Astrophysics Data System (ADS)

Dong, Yue; He, Weihua; Li, Chao; Liang, Dandan; Qu, Youpeng; Han, Xiaoyu; Feng, Yujie

2018-04-01

A novel hybrid bioelectrochemical membrane reactor with integrated microfiltration membrane as the separator between electrodes is developed for domestic wastewater treatment. After accumulation of biofilm, the organic pollutants are mainly degraded in anodic compartment, and microfiltration membrane blocks the adverse leakage of dissolved oxygen from aerated cathodic compartment. The maximum system power output is restricted by gas-water ratio following a Monod-like relationship. Within the tested gas-water ratios ranging from 0.6 to 42.9, the half-saturation constant (KQ) is 5.9 ± 0.9 with a theoretic maximum power density of 20.4 ± 1.0 W m-3. Energy balance analysis indicates an appropriate gas-water ratio regulation (from 2.3 to 28.6) for cathodic compartment is necessary to obtain positive energy output for the system. A maximum net electricity output is 9.09 × 10-3 kWh m-3 with gas-water ratio of 17.1. Notably, the system achieves the chemical oxygen demand removal of 98.3 ± 0.3%, ammonia nitrogen removal of 99.6 ± 0.1%, and total nitrogen removal of 80.0 ± 0.9%. This work verifies an effective integration of microfiltration membrane into bioelectrochemical system as separator for high-quality effluent and provides an insight into the operation and regulation of biocathode system for effective electrical energy output.

Rice mill wastewater treatment in microbial fuel cells fabricated using proton exchange membrane and earthen pot at different pH.

PubMed

Behera, Manaswini; Jana, Partha S; More, Tanaji T; Ghangrekar, M M

2010-10-01

Performance of microbial fuel cells (MFCs), fabricated using an earthen pot (MFC-1) and a proton exchange membrane (MFC-2), was evaluated while treating rice mill wastewater at feed pH of 8.0, 7.0 and 6.0. A third MFC (MFC-3), fabricated using a proton exchange membrane (PEM), was operated as control without pH adjustment of the acidic raw wastewater. Maximum chemical oxygen demand (COD) removal efficiencies of 96.5% and 92.6% were obtained in MFC-1 and MFC-2, respectively, at feed pH of 8.0. MFC-3 showed maximum COD removal of 87%. The lignin removal was 84%, 79%, and 77% and the phenol removal was 81%, 77%, and 76% in MFC-1, MFC-2, and MFC-3, respectively. Maximum sustainable volumetric power was obtained at feed pH of 8.0, and it was 2.3 W/m(3) and 0.53 W/m(3), with 100 ohm external resistance, in MFC-1 and MFC-2, respectively. The power was lower at lower feed pH. MFC-3 generated lowest volumetric power (0.27 W/m(3)) as compared to MFC-1 and MFC-2. More effective treatment of rice mill wastewater and higher energy recovery was demonstrated by earthen pot MFC as compared to MFC incorporated with PEM. 2010 Elsevier B.V. All rights reserved.

Removal of gaseous trichloroethylene (TCE) in a composite membrane biofilm reactor.

PubMed

Kumar, Amit; Vercruyssen, Aline; Dewulf, Jo; Lens, Piet; Van Langenhove, Herman

2012-01-01

A membrane biofilm reactor (MBfR) was investigated for the degradation of trichloroethylene (TCE) vapors inoculated by Burkholderia vietnamiensis G4. Toluene (TOL) was used as the primary substrate. The MBfR was loaded sequentially with TOL, TCE (or both) during 110 days. In this study, a maximum steady-state TCE removal efficiency of 23% and a maximum volumetric elimination capacity (EC) of 2.1 g m(-3) h(-1) was achieved. A surface area based maximum elimination capacity (EC(m)) of 4.2 × 10(-3) g m(-2) h(-1) was observed, which is 2-10 times higher than reported in other gas phase biological treatment studies. However, further research is needed to optimize the TCE feeding cycle and to evaluate the inhibiting effects of TCE and its intermediates on TOL biodegradation.

The mechanical design of a vapor compressor for a heat pump to be used in space

NASA Technical Reports Server (NTRS)

Berner, F.; Oesch, H.; Goetz, K.; Savage, C. J.

1982-01-01

A heat pump developed for use in Spacelab as a stand-alone refrigeration unit as well as within a fluid loop system is discussed. It will provide an active thermal control for payloads. Specifications for the heat pump were established: (1) heat removal rates at the source; (2) heat source temperatures from room temperature; (3) heat-sink fluid temperatures at condenser inlet; and (4) minimum power consumption. A reversed Carnot cycle heat pump using Freon 12 as working fluid incorporating a one-cylinder reciprocating compressor was selected. The maximum crankshaft speed was fixed relatively high at 100 rpm. The specified cooling rates then made it necessary to select a cylinder volume of 10 cu cm, which was obtained with a bore of 40 mm and a stroke of 8 mm.

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.

Divertor target for magnetic containment device

DOEpatents

Luzzi, Jr., Theodore E.

1982-01-01

In a plasma containment device of a type having superconducting field coils for magnetically shaping the plasma into approximately the form of a torus, an improved divertor target for removing impurities from a "scrape off" region of the plasma comprises an array of water cooled swirl tubes onto which the scrape off flux is impinged. Impurities reflected from the divertor target are removed from the target region by a conventional vacuum getter system. The swirl tubes are oriented and spaced apart within the divertor region relative to the incident angle of the scrape off flux to cause only one side of each tube to be exposed to the flux to increase the burnout rating of the target. The divertor target plane is oriented relative to the plane of the path of the scrape off flux such that the maximum heat flux onto a swirl tube is less than the tube design flux. The containment device is used to contain the plasma of a tokamak fusion reactor and is applicable to other long pulse plasma containment systems.

Simultaneous efficient removal of oxyfluorfen with electricity generation in a microbial fuel cell and its microbial community analysis.

PubMed

Zhang, Qinghua; Zhang, Lei; Wang, Han; Jiang, Qinrui; Zhu, Xiaoyu

2018-02-01

The performance of a microbial fuel cell (MFC) to degrade oxyfluorfen was investigated. Approximately 77% of 50 mg/L oxyfluorfen was degraded within 24 h by anodic biofilm. The temperature, pH, and initial oxyfluorfen concentration had a significant effect on oxyfluorfen degrading, and a maximum degradation rate of 94.95% could theoretically be achieved at 31.96 °C, a pH of 7.65, and an initial oxyfluorfen concentration of 120.05 mg/L. Oxyfluorfen was further catabolized through various microbial metabolism pathways. Moreover, the anodic biofilm exhibited multiple catabolic capacities to 4-nitrophenol, chloramphenicol, pyraclostrobin, and sulfamethoxazole. Microbial community analysis indicated that functional bacteria Arcobacter, Acinetobacter, Azospirillum, Azonexus, and Comamonas were the predominant genera in the anodic biofilm. In terms of the efficient removal of various organic compounds and energy recovery, the MFC seemed to be a promising approach for the treatment of environmental contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Removal of azo dye by a highly graphitized and heteroatom doped carbon derived from fish waste: Adsorption equilibrium and kinetics.

PubMed

Liu, Zhengang; Zhang, Fang; Liu, Tingting; Peng, Nana; Gai, Chao

2016-11-01

A highly graphitized and heteroatom doped porous carbon was prepared from fish waste in the present study. The morphology and chemical composition of the resultant porous carbon were characterized by SEM-EDS, TEM, BET, XRD and Raman measurement. The prepared porous carbon was employed as an adsorbent for acid orange 7, a typical azo dye, removal from aqueous solution. The results showed that the porous carbon had ultrahigh surface area of 2146 m(2)/g, a high degree of graphitization structure and naturally doped with nitrogen and phosphorous. The maximum adsorption capacity of acid orange 7 reached 285.71 mg/g due to unique property of the prepared porous carbon. In addition, acid orange 7 adsorption onto the porous carbon well followed pseudo-second-order kinetics model and acid orange 7 diffusion in micropores was the potential rate controlling step. Copyright © 2016 Elsevier Ltd. All rights reserved.

Jute stick powder as a potential biomass for the removal of congo red and rhodamine B from their aqueous solution.

PubMed

Panda, Gopal C; Das, Sujoy K; Guha, Arun K

2009-05-15

Jute stick powder (JSP) has been found to be a promising material for adsorptive removal of congo red (C.I. 22120) and rhodamine B (C.I. 45170) from aqueous solutions. Physico-chemical parameters like dye concentration, solution pH, temperature and contact time have been varied to study the adsorption phenomenon. Favorable adsorption occurs at around pH 7.0 whereas temperature has no significant effect on adsorption of both the dyes. The maximum adsorption capacity has been calculated to be 35.7 and 87.7mg/g of the biomass for congo red and rhodamine B, respectively. The adsorption process is in conformity with Freundlich and Langmuir isotherms for rhodamine B whereas congo red adsorption fits well to Langmuir isotherm only. In both the cases, adsorption occurs very fast initially and attains equilibrium within 60min. Kinetic results suggest the intra-particle diffusion of dyes as rate limiting step.

Optimization of Malachite Green Removal from Water by TiO₂ Nanoparticles under UV Irradiation.

PubMed

Ma, Yongmei; Ni, Maofei; Li, Siyue

2018-06-13

TiO₂ nanoparticles with surface porosity were prepared by a simple and efficient method and presented for the removal of malachite green (MG), a representative organic pollutant, from aqueous solution. Photocatalytic degradation experiments were systematically conducted to investigate the influence of TiO₂ dosage, pH value, and initial concentrations of MG. The kinetics of the reaction were monitored via UV spectroscopy and the kinetic process can be well predicted by the pseudo first-order model. The rate constants of the reaction kinetics were found to decrease as the initial MG concentration increased; increased via elevated pH value at a certain amount of TiO₂ dosage. The maximum efficiency of photocatalytic degradation was obtained when the TiO₂ dosage, pH value and initial concentrations of MG were 0.6 g/L, 8 and 10 −5 mol/L (M), respectively. Results from this study provide a novel optimization and an efficient strategy for water pollutant treatment.

Optimization of A(2)O BNR processes using ASM and EAWAG Bio-P models: model performance.

PubMed

El Shorbagy, Walid E; Radif, Nawras N; Droste, Ronald L

2013-12-01

This paper presents the performance of an optimization model for a biological nutrient removal (BNR) system using the anaerobic-anoxic-oxic (A(2)O) process. The formulated model simulates removal of organics, nitrogen, and phosphorus using a reduced International Water Association (IWA) Activated Sludge Model #3 (ASM3) model and a Swiss Federal Institute for Environmental Science and Technology (EAWAG) Bio-P module. Optimal sizing is attained considering capital and operational costs. Process performance is evaluated against the effect of influent conditions, effluent limits, and selected parameters of various optimal solutions with the following results: an increase of influent temperature from 10 degrees C to 25 degrees C decreases the annual cost by about 8.5%, an increase of influent flow from 500 to 2500 m(3)/h triples the annual cost, the A(2)O BNR system is more sensitive to variations in influent ammonia than phosphorus concentration and the maximum growth rate of autotrophic biomass was the most sensitive kinetic parameter in the optimization model.

Bioconversion of paper mill sludge to bioethanol in the presence of accelerants or hydrogen peroxide pretreatment.

PubMed

Gurram, Raghu Nandan; Al-Shannag, Mohammad; Lecher, Nicholas Joshua; Duncan, Shona M; Singsaas, Eric Lawrence; Alkasrawi, Malek

2015-09-01

In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of hydrous zirconium oxide-impregnated chitosan beads and their application for removal of fluoride and lead

NASA Astrophysics Data System (ADS)

Cho, Dong-Wan; Jeon, Byong-Hun; Jeong, Yoojin; Nam, In-Hyun; Choi, Ui-Kyu; Kumar, Rahul; Song, Hocheol

2016-05-01

A composite adsorbent capable of simultaneous removal of both cationic and anionic contaminants from aqueous solutions was developed by impregnating hydrous zirconium oxide (HZO) into chitosan beads (CB). The optimal mass ratio of chitosan to HZO was 2:2. The composite adsorbent (HZOCB) had the rugged surface (52.74 m2 g-1) with irregular cracks caused by HZO inclusion and amine functional groups. The rate of Pb2+ adsorption by HZOCB was relatively rapid. Most of Pb2+ (89%) was adsorbed within 2.5 h. A binary sorbate system was noticeably favorable for F- adsorption as compared to single sorbate system. Adsorption of F- and Pb2+ followed pseudo-second order kinetics. The maximum sorption capacities obtained from Langmuir isotherm model were 22.1 and 222.2 mg g-1, respectively. The study demonstrates that the developed composite could be a potential adsorbent for the simultaneous remediation of F- and Pb2+ contamination in water.

Modacrylic anion-exchange fibers for Cr(VI) removal from chromium-plating rinse water in batch and flow-through column experiments.

PubMed

Lee, Seung-Chan; Kang, Jin-Kyu; Sim, Eun-Hye; Choi, Nag-Choul; Kim, Song-Bae

2017-11-10

The aim of this study was to investigate Cr(VI) removal from chromium-plating rinse water using modacrylic anion-exchange fibers (KaracaronTM KC31). Batch experiments were performed with synthetic Cr(VI) solutions to characterize the KC31 fibers in Cr(VI) removal. Cr(VI) removal by the fibers was affected by solution pH; the Cr(VI) removal capacity was the highest at pH 2 and decreased gradually with a pH increase from 2 to 12. In regeneration and reuse experiments, the Cr(VI) removal capacity remained above 37.0 mg g -1 over five adsorption-desorption cycles, demonstrating that the fibers could be successfully regenerated with NaCl solution and reused. The maximum Cr(VI) removal capacity was determined to be 250.3 mg g -1 from the Langmuir model. In Fourier-transform infrared spectra, a Cr = O peak newly appeared at 897 cm -1 after Cr(VI) removal, whereas a Cr-O peak was detected at 772 cm -1 due to the association of Cr(VI) ions with ion-exchange sites. X-ray photoelectron spectroscopy analyses demonstrated that Cr(VI) was partially reduced to Cr(III) after the ion exchange on the surfaces of the fibers. Batch experiments with chromium-plating rinse water (Cr(VI) concentration = 1178.8 mg L -1 ) showed that the fibers had a Cr(VI) removal capacity of 28.1-186.4 mg g -1 under the given conditions (fiber dose = 1-10 g L -1 ). Column experiments (column length = 10 cm, inner diameter = 2.5 cm) were conducted to examine Cr(VI) removal from chromium-plating rinse water by the fibers under flow-through column conditions. The Cr(VI) removal capacities for the fibers at flow rates of 0.5 and 1.0 mL min -1 were 214.8 and 171.5 mg g -1 , respectively. This study demonstrates that KC31 fibers are effective in the removal of Cr(VI) ions from chromium-plating rinse water.

Removal Efficiency of the Heavy Metals Zn(II), Pb(II) and Cd(II) by Saprolegnia delica and Trichoderma viride at Different pH Values and Temperature Degrees

PubMed Central

Hashem, Mohamed

2007-01-01

The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees,was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum biomass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn,Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature 20℃ in case of S. delica while it was 25℃ for T. viride. Incubation of T. viride at higher temperatures (30℃ and 35℃) enhanced the removal efficiency of Pb and Cd than low temperatures (15℃ and 20℃) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all temperature degrees of incubation and Cd bioaccumulation was the lowest whereas T. viride showed the highest removal efficiency for Pb followed by Cd and Zn was the minor of the heavy metals. PMID:24015084

Ion-recombination correction for different ionization chambers in high dose rate flattening-filter-free photon beams

NASA Astrophysics Data System (ADS)

Lang, Stephanie; Hrbacek, Jan; Leong, Aidan; Klöck, Stephan

2012-05-01

Recently, there has been an increased interest in flattening-filter-free (FFF) linear accelerators. Removal of the filter results in available dose rates up to 24 Gy min-1 (for nominal energy 10 MV in depth of maximum dose, a source-surface distance of 100 cm and a field size of 10×10 cm2). To guarantee accurate relative and reference dosimetry for the FFF beams, we investigated the charge collection efficiency of multiple air-vented and one liquid ionization chamber for dose rates up to 31.9 Gy min-1. For flattened beams, the ion-collection efficiency of all air-vented ionization chambers (except for the PinPoint chamber) was above 0.995. By removing the flattening filter, we found a reduction in collection efficiency of approximately 0.5-0.9% for a 10 MV beam. For FFF beams, the Markus chamber showed the largest collection efficiency of 0.994. The observed collection efficiencies were dependent on dose per pulse, but independent of the pulse repetition frequency. Using the liquid ionization chamber, the ion-collection efficiency for flattened beams was above 0.990 for all dose rates. However, this chamber showed a low collection efficiency of 0.940 for the FFF 10 MV beam at a dose rate of 31.9 Gy min-1. All investigated air-vented ionization chambers can be reliably used for relative dosimetry of FFF beams. The order of correction for reference dosimetry is given in the manuscript. Due to their increased saturation in high dose rate FFF beams, liquid ionization chambers appear to be unsuitable for dosimetry within these contexts.

THE EFFECT OF PH, PHOSPHATE AND OXIDANT ON THE REMOVAL OF ARSENIC FROM DRINKING WATER DURING IRON REMOVAL

EPA Science Inventory

Arsenic is a naturally occurring drinking water contaminant that has known adverse human health effects. The recent compilation of new health effects data prompted the U.S. Environmental Protection Agency (USEPA) to reduce the previous arsenic maximum contaminant level (MCL) of ...

THE EFFECT OF PH, PHOSPHATE AND OXIDANT ON THE REMOVAL OF ARSENIC FROM DRINKING WATER DURING IRON REMOVAL

EPA Science Inventory

Arsenic is a naturally occurring drinking water contaminant that has known adverse human health effects. The recent compilation of new health effects data prompted the U.S. Environmental Protection Agency (USEPA) to recently reduce the previous arsenic maximum contaminant level ...

Regenerating an Arsenic Removal Iron-Based Adsorptive Media System, Part 1: The Regeneration Process

EPA Science Inventory

Adsorptive media technology is a frequently used method of removing arsenic by small water systems because of its simplicity and efficiency. Current practice is to replace the media when it no longer reduces arsenic below the USEPA drinking water maximum contaminant level (MCL) ...

ARSENIC REMOVAL FROM DRINKING WATER BY ACTIVATED ALUMINA AND ANION EXCHANGE TREATMENT

EPA Science Inventory

In preparation of the U.S. Environmental Protection Agency (USEPA) revising the arsenic maximum contaminant level (MCL) in the year 2001, a project was initiated to evaluate the performance of nine, full-scale drinking water treatment plants for arsenic removal. Four of these sy...

Submerged anaerobic membrane bioreactor (SAnMBR) performance on sewage treatment: removal efficiencies, biogas production and membrane fouling.

PubMed

Chen, Rong; Nie, Yulun; Ji, Jiayuan; Utashiro, Tetsuya; Li, Qian; Komori, Daisuke; Li, Yu-You

2017-09-01

A submerged anaerobic membrane reactor (SAnMBR) was employed for comprehensive evaluation of sewage treatment at 25 °C and its performance in removal efficiency, biogas production and membrane fouling. Average 89% methanogenic degradation efficiency as well as 90%, 94% and 96% removal of total chemical oxygen demand (TCOD), biochemical oxygen demand (BOD) and nonionic surfactant were obtained, while nitrogen and phosphorus were only subjected to small removals. Results suggest that SAnMBRs can effectively decouple organic degradation and nutrients disposal, and reserve all the nitrogen and phosphorus in the effluent for further possible recovery. Small biomass yields of 0.11 g mixed liquor volatile suspended solids (MLVSS)/gCOD were achieved, coupled to excellent methane production efficiencies of 0.338 NLCH 4 /gCOD, making SAnMBR an attractive technology characterized by low excess sludge production and high bioenergy recovery. Batch tests revealed the SAnMBR appeared to have the potential to bear a high food-to-microorganism ratio (F/M) of 1.54 gCOD/gMLVSS without any inhibition effect, and maximum methane production rate occurred at F/M 0.7 gCOD/gMLVSS. Pore blocking dominated the membrane fouling behaviour at a relative long hydraulic retention time (HRT), i.e. >12 hours, while cake layer dominated significantly at shorter HRTs, i.e. <8 hours.

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.

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.

Ultrasonic enhancement of the simultaneous removal of quaternary toxic organic dyes by CuO nanoparticles loaded on activated carbon: Central composite design, kinetic and isotherm study.

PubMed

Dashamiri, Somayeh; Ghaedi, Mehrorang; Dashtian, Kheibar; Rahimi, Mahmood Reza; Goudarzi, Alireza; Jannesar, Ramin

2016-07-01

Copper oxide nanoparticles loaded on activated carbon (CuO-NPs-AC) were prepared and fully analyzed and characterized with FE-SEM, XRD and FT-IR. Subsequently, this novel material was used for simultaneous ultrasound-assisted adsorption of brilliant green (BG), auramine O (AO), methylene blue (MB) and eosin yellow (EY) dyes. Problems regard to dyes spectra overlap in quaternary solution of this dyes were omitted by derivative spectrophotometric method. The best pH in quaternary system was studied by using one at a time method to achieved maximum dyes removal percentage. Subsequently, sonication time, adsorbent dosage and initial dyes concentrations influence on dyes removal was optimized by central composite design (CCD) combined with desirability function approach (DFA). Desirability score of 0.978 show optimum conditions set at sonication time (4.2 min), adsorbent mass (0.029 g), initial dyes concentration (4.5 mg L(-1)). Under this optimum condition the removal percentage for MB, AO, EY and BG dyes 97.58, 94.66, 96.22 and 94.93, respectively. The adsorption rate well fitted by pseudo second-order while adsorption capacity according to the Langmuir model as best equilibrium isotherm model for BG, MB, AO and EY was 20.48, 21.26, 22.34 and 21.29 mg g(-1), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Treatment of methylene blue containing wastewater by a cost-effective micro-scale biochar/polysulfone mixed matrix hollow fiber membrane: Performance and mechanism studies.

PubMed

He, Jinsong; Cui, Anan; Deng, Shihuai; Chen, J Paul

2018-02-15

Dye containing wastewater has increasingly become an important contamination due to operation of various industries such as textile industry. In this study, a micro-scale biochar particles/polysulfone mixed matrix hollow fiber membrane (MMM) was applied for the removal of methylene blue from water. The static and dynamic adsorption performance was investigated. We found that the MMM exhibited a high removal efficiency of methylene blue under a wide pH range of 4-10. The adsorption process on biochar and MMM obeyed the intraparticle surface diffusion model and Langmuir isotherm model. At neutral pH, the maximum adsorption capacity was 544.459 mg/g for biochar and 165.808 mg/g for MMM. Better regeneration with a desorption rate above 92% was achieved by 1-M NaCl in 90% ethanol aqueous solution. Furthermore, the MMM displayed good performance in treating methylene blue containing wastewater through a continuous filtration mode. More importantly, the MMM showed an excellent reusability for methylene blue removal; it was able to achieve 81% of the permeate yield of the fresh MMM after three regeneration cycles. Finally, the adsorption mechanism studies indicated that the removal of methylene blue was associated with electrostatic interaction, hydrogen bonding and hydrophobic interaction. Copyright © 2017 Elsevier Inc. All rights reserved.

Adsorption of heavy metal ions by hierarchically structured magnetite-carbonaceous spheres.

PubMed

Gong, Jingming; Wang, Xiaoqing; Shao, Xiulan; Yuan, Shuang; Yang, Chenlin; Hu, Xianluo

2012-11-15

Magnetically driven separation technology has received considerable attention in recent decade for its great potential application. In this work, hierarchically structured magnetite-carbonaceous microspheres (Fe(3)O(4)-C MSs) have been synthesized for the adsorption of heavy metal ions from aqueous solution. Each sphere contains numerous unique rattle-type structured magnetic particles, realizing the integration of rattle-type building unit into microspheres. The as-prepared composites with high BET surface area, hierarchical as well as mesoporous structures, exhibit an excellent adsorption capacity for heavy metal ions and a convenient separation procedure with the help of an external magnet. It was found that the maximum adsorption capacity of the composite toward Pb(2+) was ∼126mgg(-1), displaying a high efficiency for the removal of heavy metal ions. The Freundlich adsorption isotherm was applicable to describe the removal processes. Kinetics of the Pb(2+) removal was found to follow pseudo-second-order rate equation. The as-prepared composite of Fe(3)O(4)-C MSs as well as Pb(2+)-adsorbed composite were carefully examined by scanning electron microscopy (SEM), Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), nitrogen sorption measurements, and X-ray photoelectron spectroscopy (XPS). Based on the characterization results, a possible mechanism of Pb(2+) removal with the composite of Fe(3)O(4)-C MSs was proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

H2S and volatile fatty acids elimination by biofiltration: clean-up process for biogas potential use.

PubMed

Ramírez-Sáenz, D; Zarate-Segura, P B; Guerrero-Barajas, C; García-Peña, E I

2009-04-30

In the present work, the main objective was to evaluate a biofiltration system for removing hydrogen sulfide (H(2)S) and volatile fatty acids (VFAs) contained in a gaseous stream from an anaerobic digestor (AD). The elimination of these compounds allowed the potential use of biogas while maintaining the methane (CH(4)) content throughout the process. The biodegradation of H(2)S was determined in the lava rock biofilter under two different empty bed residence times (EBRT). Inlet loadings lower than 200 g/m(3)h at an EBRT of 81 s yielded a complete removal, attaining an elimination capacity (EC) of 142 g/m(3)h, whereas at an EBRT of 31 s, a critical EC of 200 g/m(3)h was reached and the EC obtained exhibited a maximum value of 232 g/m(3)h. For 1500 ppmv of H(2)S, 99% removal was maintained during 90 days and complete biodegradation of VFAs was observed. A recovery of 60% as sulfate was obtained due to the constant excess of O(2) concentration in the system. Acetic and propionic acids as a sole source of carbon were also evaluated in the bioreactor at different inlet loadings (0-120 g/m(3)h) obtaining a complete removal (99%) for both. Microcosms biodegradation experiments conducted with VFAs demonstrated that acetic acid provided the highest biodegradation rate.

Nitrogen removal from wastewater through microbial electrolysis cells and cation exchange membrane.

PubMed

Haddadi, Sakineh; Nabi-Bidhendi, Gholamreza; Mehrdadi, Nasser

2014-02-17

Vulnerability of water resources to nutrients led to progressively stricter standards for wastewater effluents. Modification of the conventional procedures to meet the new standards is inevitable. New technologies should give a priority to nitrogen removal. In this paper, ammonium chloride and urine as nitrogen sources were used to investigate the capacity of a microbial electrolysis cell (MEC) configured by cation exchange membrane (CEM) for electrochemical removal of nitrogen over open-and closed-circuit potentials (OCP and CCP) during biodegradation of organic matter. Results obtained from this study indicated that CEM was permeable to both organic and ammonium nitrogen over OCP. Power substantially mediated ammonium migration from anodic wastewater to the cathode, as well. With a urine rich wastewater in the anode, the maximum rate of ammonium intake into the cathode varied from 34.2 to 40.6 mg/L.h over CCP compared to 10.5-14.9 mg/L.h over OCP. Ammonium separation over CCP was directly related to current. For 1.46-2.12 mmol electron produced, 20.5-29.7 mg-N ammonium was removed. Current also increased cathodic pH up to 12, a desirable pH for changing ammonium ion to ammonia gas. Results emphasized the potential for MEC in control of ammonium through ammonium separation and ammonia volatilization provided that membrane characteristic is considered in their development.

Nickel removal by biosorption onto medlar male flowers coupled with photocatalysis on the spinel ZnMn2O4

PubMed Central

2014-01-01

Ni2+ is a highly toxic above 0.07 mg/L and its removal is of high significance. The biosorption of Ni2+ onto medlar male flowers (MMF) was studied in relation with the physical parameters like pH, contact time, biosorbent dosage, Ni2+ concentration and temperature. The interaction biosorbent-Ni2+ was examined by the FTIR technique. The equilibrium was achieved within 40 min and the data were well fitted by the Langmuir and Redlich-Peterson (R-P) models. The maximum Ni2+ uptake capacity was 17.073 mg/g at 25°C and the Ni2+ removal follows a pseudo-second order kinetic with activation energy of 13.3 kJ/mol. The thermodynamic parameters: ΔS°, ΔH° and ΔG° showed that the biosorption was spontaneous and endothermic. MMF was used as a post treatment technique and the biosorption was coupled with the visible light driven Ni2+ reduction over the spinel ZnMn2O4. The effect of the pH, ZnMn2O4 loading and light intensity on the photoactivity was investigated. 77.5% of Ni2+ was reduced after ~140 min under optimal conditions. The Ni2+ removal reached a rate conversion of 96% of with the coupled system biosorption/photocatalysis is very promising for the water treatment. PMID:24401700

Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

PubMed

Ismail, Zainab Z; AbdelKareem, Hala N

2015-11-01

Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Temperature effect on nitrogen removal performance and bacterial community in culture of marine anammox bacteria derived from sea-based waste disposal site.

PubMed

Kawagoshi, Yasunori; Fujisaki, Koichiro; Tomoshige, Yuki; Yamashiro, Kento; Wei, Qiaoyan; Qiao, Yanwei

2012-04-01

Anaerobic ammonium oxidation (anammox) bacteria have been detected in variety of marine environment in recent years, however, there have been only a few studies on their characteristics in the culture. The aim of this study is to reveal the effect of temperature on nitrogen removal ability and bacterial community in a culture of marine anammox bacteria (MAAOB). The MAAOB were cultured from the sediment of a sea-based waste disposal site at the North Port of Osaka Bay in Japan. The maximum nitrogen removal rate (NRR) was observed at 25°C in the MAAOB culture, and it decreased both at below 20°C and over 33°C. The activation energy of the MAAOB culture was calculated to be 54.6 kJ mol(-1) in the 5°C to 30°C range. No significant change in bacterial community according with temperature (5-37°C) was confirmed in the results of polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE). Meanwhile, a number of bacteria related to the oxidation-reduction reaction of sulfur were confirmed and it is speculated that they involved in the activity of MAAOB and nitrogen removal ability in the culture. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Cultivation of Chlorella vulgaris in a pilot-scale photobioreactor using real centrate wastewater with waste glycerol for improving microalgae biomass production and wastewater nutrients removal.

PubMed

Ren, Hongyan; Tuo, Jinhua; Addy, Min M; Zhang, Renchuan; Lu, Qian; Anderson, Erik; Chen, Paul; Ruan, Roger

2017-12-01

To improve nutrients removal from real centrate wastewater and enhance the microalgae biomass production, cultivation of Chlorella vulgaris in lab and a pilot-scale photobioreactor with waste glycerol was studied. The results showed the optimal concentration of the crude glycerol was 1.0gL -1 with the maximum biomass productivity of 460mgL -1 d -1 TVS, the maximum lipid content of 27%, the nutrient removal efficiency of all above 86%, due to more balanced C/N ratio. The synergistic relationship between the wastewater-borne bacteria and the microalgae had significant good influence on nutrient removal. In pilot-scale wastewater-based algae cultivation, with 1gL -1 waste glycerol addition, the average biomass production of 16.7gm -2 d -1 , lipid content of 23.6%, and the removal of 2.4gm -2 d -1 NH 4 + -N, 2.7gm -2 d -1 total nitrogen, 3.0gm -2 d -1 total phosphorous, and 103.0gm -2 d -1 of COD were attained for 34days semi-continuous mode. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evolution of CO2 in lakes Monoun and Nyos, Cameroon, before and during controlled degassing

USGS Publications Warehouse

Kusakabe, M.; Ohba, T.; Issa,; Yoshida, Y.; Satake, H.; Ohizumi, T.; Evans, William C.; Tanyileke, G.; Kling, G.W.

2008-01-01

Evolution of CO2 in Lakes Monoun and Nyos (Cameroon) before and during controlled degassing is described using results of regular monitoring obtained during the last 21 years. The CO2(aq) profiles soon after the limnic eruptions were estimated for Lakes Monoun and Nyos using the CTD data obtained in October and November 1986, respectively. Based on the CO2(aq) profiles through time, the CO2 Content and its change over time were calculated for both lakes. The CO2 accumulation rate calculated from the pre-degassing data, was constant after the limnic eruption at Lake Nyos (1986-2001), whereas the rate appeared initially high (1986-1996) but later slowed down (1996-2003) at Lake Monoun. The CO2 concentration at 58 m depth in Lake Monoun in January 2003 was very close to saturation due to the CO2 accumulation. This situation is suggestive of a mechanism for the limnic eruption, because it may take place spontaneously without receiving an external trigger. The CO2 content of the lakes decreased significantly after controlled degassing started in March 2001 at Lake Nyos and in February 2003 at Lake Monoun. The current content is lower than the content estimated soon after the limnic eruption at both lakes. At Monoun the degassing rate increased greatly after February 2006 due to an increase of the number of degassing pipes and deepening of the pipe intake depth. The current CO2 content is ???40% of the maximum content attained just before the degassing started. At current degassing rates the lower chemocline will subside to the degassing pipe intake depth of 93 m in about one year. After this depth is reached, the gas removal rate will progressively decline because water of lower CO2(aq) concentration will be tapped by the pipes. To keep the CO2 content of Lake Monoun as small as possible, it is recommended to set up a new, simple device that sends deep water to the surface since natural recharge of CO2 will continue. Controlled degassing at Lake Nyos since 2001 has also reduced the CO2 content. It is currently slightly below the level estimated after the limnic eruption in 1986. However, the current CO2 content still amounts to 80% of the maximum level of 14.8 giga moles observed in January 2001. The depth of the lower chemocline may reach the pipe intake depth of 203 m within a few years. After this situation is reached the degassing rate with the current system will progressively decline, and it would take decades to remove the majority of dissolved gases even if the degassing system keeps working continuously. Additional degassing pipes must be installed to speed up gas removal from Lake Nyos in order to make the area safer for local populations. Copyright ?? 2008 by The Geochemical Society of Japan.

Termites and large herbivores influence seed removal rates in an African savanna.

PubMed

Acanakwo, Erik Francis; Sheil, Douglas; Moe, Stein R

2017-12-01

Seed removal can influence plant community dynamics, composition, and resulting vegetation characteristics. In the African savanna, termites and large herbivores influence vegetation in various ways, likely including indirect effects on seed predators and secondary dispersers. However, the intensity and variation of seed removal rates in African savannas has seldom been studied. We experimentally investigated whether termites and large herbivores were important factors in the mechanisms contributing to observed patterns in tree species composition on and off mounds, in Lake Mburo National Park, Uganda. Within fenced (excluding large herbivores) and unfenced termite mound and adjacent savanna plots, we placed seeds of nine native tree species within small open "cages," accessed by all animals, roofed cages that only allowed access to small vertebrates and invertebrates, and closed cages that permitted access by smaller invertebrates only (5 mm wire mesh). We found that mean seed removal rate was high (up to 87.3% per 3 d). Mound habitats experienced significantly higher removal rates than off-mound habitats. The mean removal rate of native seeds from closed cages was 11.1% per 3 d compared with 19.4% and 23.3% removed per 3 d in the roofed and open cages, respectively. Smaller seeds experienced higher removal rates than larger seeds. Large herbivore exclusion on mounds reduced native seed removal rates by a mean of 8.8% in the open cages, but increased removal rates by 1.7% in the open cages when off-mound habitats were fenced. While removal rates from open cages were higher on active mounds (30.9%) than on inactive mounds (26.7%), the removal rates from closed cages were lower on active vs. inactive mounds (6.1% vs. 11.6%, respectively). Thus, we conclude that large herbivores and Macrotermes mounds influence seed removal rates, though these effects appear indirect. © 2017 by the Ecological Society of America.

Zero-valent iron for the abatement of arsenate and selenate from flowback water of hydraulic fracturing.

PubMed

Sun, Yuqing; Chen, Season S; Tsang, Daniel C W; Graham, Nigel J D; Ok, Yong Sik; Feng, Yujie; Li, Xiang-Dong

2017-01-01

Zero-valent iron (ZVI) was tested for the removal of 150 μg L -1 As(V) and 350 μg L -1 Se(VI) in high-salinity (ionic strength 0.35-4.10 M) flowback water of hydraulic fracturing. Over 90% As(V) and Se(VI) was removed by 2.5 g L -1 ZVI in Day-14 flowback water up to 96-h reaction, with the remaining concentration below the maximum contaminant level for As(V) and criterion continuous concentration for Se(VI) recommended by US EPA. The kinetics of As(V) and Se(VI) removal followed a pseudo-second-order rate expression with the observed rates of 4.51 × 10 -2 -4.91 × 10 -1 and 3.48 × 10 -2 -6.58 × 10 -1 h -1 (with 0.5-10 g L -1 ZVI), respectively. The results showed that Se(VI) removal significantly decreased with increasing ionic strength, while As(V) removal showed little variation. Common competing anions (nitrate, bicarbonate, silicate, and phosphate), present in shallow groundwater and stormwater, caused marginal Se(VI) desorption (2.42 ± 0.13%) and undetectable As(V) desorption from ZVI. The competition between As(V) and Se(VI) for ZVI removal depended on the initial molar ratio and surface sites, which occurred when the Se(VI) concentration was higher than the As(V) concentration in this study. The characterization of As(V)- and Se(VI)-loaded ZVI by X-ray diffraction and Raman analysis revealed that ZVI gradually converted to magnetite/maghemite corrosion products with lepidocrocite in flowback water over 30 days. Similar corrosion compositions were confirmed in aerobic and anaerobic conditions regardless of the molar ratio of As(V) to Se(VI). The high reactivity and stability of ZVI showed its suitability for in-situ prevention of As(V) and Se(VI) migration due to accidental leakage, spillage, or overflow of flowback water. Copyright © 2016 Elsevier Ltd. All rights reserved.

7 CFR 3565.210 - Maximum interest rate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Maximum interest rate. 3565.210 Section 3565.210... AGRICULTURE GUARANTEED RURAL RENTAL HOUSING PROGRAM Loan Requirements § 3565.210 Maximum interest rate. The interest rate for a guaranteed loan must not exceed the maximum allowable rate specified by the Agency in...

Kinetics of anaerobic treatment of landfill leachates combined with urban wastewaters.

PubMed

Fueyo, Gema; Gutiérrez, Antonio; Berrueta, José

2003-04-01

The anaerobic degradation of landfill leachates mixed with domestic wastewater has been studied in a pilot-scale Upflow Anaerobic Sludge Blanket (UASB) reactor. A previous work in laboratory-scale had shown that a fraction (5%) of the refractory organic matter could be additionally degraded when these two substrates were treated in conjunction, but this synergistic effect in the Chemical Oxygen Demand (COD) removal was not reproduced. However, the mass loading rate for which the maximum degradation was obtained was higher for the mixtures (0.5 kg COD/kg SSV x d) than for the separated components (0.18 and 0.19), allowing an increase in the treatment capacity of the leachates. The methane productivity (304 L/kg COD) was close to the theoretical maximum and independent of the proportion of the mixture components. The experimental data were fitted to a modification of Haldane's kinetic model, in which the parameters depend on the hydraulic residence time and the biomass concentration.

Kinetics of nitrate and sulfate removal using a mixed microbial culture with or without limited-oxygen fed.

PubMed

Xu, Xi-Jun; Chen, Chuan; Wang, Ai-Jie; Guo, Hong-Liang; Yuan, Ye; Lee, Duu-Jong; Ren, Nan-Qi

2014-07-01

The biological degradation of nitrate and sulfate was investigated using a mixed microbial culture and lactate as the carbon source, with or without limited-oxygen fed. It was found that sulfate reduction was slightly inhibited by nitrate, since after nitrate depletion the sulfate reduction rate increased from 0.37 mg SO4 (2-)/mg VSS d to 0.71 mg SO4 (2-)/mg VSS d, and the maximum rate of sulfate reduction in the presence of nitrate corresponded to 56 % of the non-inhibited sulfate reduction rate determined after nitrate depleted. However, simultaneous but not sequential reduction of both oxy-anions was observed in this study, unlike some literature reports in which sulfate reduction starts only after depletion of nitrate, and this case might be due to the fact that lactate was always kept above the limiting conditions. At limited oxygen, the inhibited effect on sulfate reduction by nitrate was relieved, and the sulfate reduction rate seemed relatively higher than that obtained without limited-oxygen fed, whereas kept almost constant (0.86-0.89 mg SO4 (2-)/mg VSS d) cross the six ROS states. In contrast, nitrate reduction rates decreased substantially with the increase in the initial limited-oxygen fed, showing an inhibited effect on nitrate reduction by oxygen. Kinetic parameters determined for the mixed microbial culture showed that the maximum specific sulfate utilization rate obtained (0.098 ± 0.022 mg SO4 (2-)/(mg VSS h)) was similar to the reported typical value (0.1 mg SO4 (2-)/(mg VSS h)), also indicating a moderate inhibited effect by nitrate.

Arsenic processing of yeast isolates IIB-As1 & IIB-As2 and production of glutathione under stress conditions.

PubMed

Muneer, Bushra; Lali, Tayyaba; Iqbal, Muhammad J; Shakoori, Farah R; Shakoori, Abdul R

2016-10-01

Four arsenic resistant yeast were isolated from the industrial wastewater. Two strains IIB-As1 and IIB-As2 identified as Candida tropicalis and Saccharomyces cerevisiae, respectively. IIB-As1 and IIB-As2 showed maximum arsenic resistance. IIB-As1 showed maximum growth at 35 °C whereas it was 30 °C for IIB-As2. The yeast isolate showed typical growth curves, but arsenic extended the lag phase. Glutathione plays an important role in metal tolerance. In the present study, As increased the level glutathione and non-protein thiols in yeast isolates. Removal of As from supernatant was analyzed using the atomic absorption spectrophotometer. They removed arsenic from the medium after 72 h of incubation. Both yeast strains efficiently removed arsenic from the industrial effluent when used individually or in consortia. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

COD removal characteristics in air-cathode microbial fuel cells.

PubMed

Zhang, Xiaoyuan; He, Weihua; Ren, Lijiao; Stager, Jennifer; Evans, Patrick J; Logan, Bruce E

2015-01-01

Exoelectrogenic microorganisms in microbial fuel cells (MFCs) compete with other microorganisms for substrate. In order to understand how this affects removal rates, current generation, and coulombic efficiencies (CEs), substrate removal rates were compared in MFCs fed a single, readily biodegradable compound (acetate) or domestic wastewater (WW). Removal rates based on initial test conditions fit first-order kinetics, but rate constants varied with circuit resistance. With filtered WW (100Ω), the rate constant was 0.18h(-)(1), which was higher than acetate or filtered WW with an open circuit (0.10h(-)(1)), but CEs were much lower (15-24%) than acetate. With raw WW (100Ω), COD removal proceeded in two stages: a fast removal stage with high current production, followed by a slower removal with little current. While using MFCs increased COD removal rate due to current generation, secondary processes will be needed to reduce COD to levels suitable for discharge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biosorptive uptake of arsenic(V) by steam activated carbon from mung bean husk: equilibrium, kinetics, thermodynamics and modeling

NASA Astrophysics Data System (ADS)

Mondal, Sandip; Aikat, Kaustav; Halder, Gopinath

2017-12-01

The present investigation emphasizes on the biosorptive removal of toxic pentavalent arsenic from water using steam activated carbon prepared from mung bean husk (SAC-MBH). Characterization of the synthesized sorbent was done using different instrumental techniques, i.e., SEM, BET and point of zero charge. Sorptive uptake of As(V) over steam activated MBH as a function of pH (3-9), agitation speed (40-200 rpm), dosage (50-1000 mg) and temperature (298-313 K) was studied by batch process at arsenic concentration of 2 mg L-1. Lower pH increases the arsenic removal over the pH range of 3-9. Among three adsorption isotherm models examined, Langmuir model was observed to show superior results over Freundlich model. The mean sorption energy (E) estimated by Dubinin-Radushkevich model suggested that the process of adsorption was chemisorption. Thermodynamic parameters confer that the sorption process was spontaneous, exothermic and feasible in nature. The pseudo-second-order rate kinetics of arsenic gave better correlation coefficients as compared to pseudo-first-order kinetics equation. Three process parameters, viz. adsorbent dosage, agitation speed and pH were opted for optimizing As(V) elimination using central composite design matrix of response surface methodology (RSM). The identical design setup was used for artificial neural network (ANN) for comparing its prediction capability with RSM towards As(V) removal. Maximum arsenic removal was observed to be 98.75% at sorbent dosage 0.75 gm L-1, pH 3.0, agitation speed 160 rpm and temperature 308 K. The study concluded that SAC-MBH could be a competent adsorbent for As(V) removal and ANN model was better in arsenic removal predictability results than RSM model.

Defense Science Board Summer Study on Autonomy

DTIC Science & Technology

2016-06-01

hours, at a maximum velocity of 40 mph, with a maximum payload of 9 kg (20 lbs); a maximum range of 160 km (100 miles); and can operate in wind /gust...existing mine disposal platform, such as Seafox, with contact reacquisition and neutralization capability. Seafox is a wire -guided mine neutralizer...functions, will retain operator control of neutralization and will remove the need for personnel to enter the minefield to execute fly- by- wire

29 CFR 1915.112 - Ropes, chains and slings.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., defective welds, deformation and increase in length or stretch. (3) Employers must note interlink wear, not accompanied by stretch in excess of 5 percent, and remove the chain from service when maximum allowable wear... shall be removed from service when, due to stretch, the increase in length of a measured section exceeds...

29 CFR 1915.112 - Ropes, chains and slings.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., defective welds, deformation and increase in length or stretch. (3) Employers must note interlink wear, not accompanied by stretch in excess of 5 percent, and remove the chain from service when maximum allowable wear... shall be removed from service when, due to stretch, the increase in length of a measured section exceeds...

29 CFR 1915.112 - Ropes, chains and slings.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., defective welds, deformation and increase in length or stretch. (3) Employers must note interlink wear, not accompanied by stretch in excess of 5 percent, and remove the chain from service when maximum allowable wear... shall be removed from service when, due to stretch, the increase in length of a measured section exceeds...

NITRIFICATION AND ARSENIC REMOVAL IN BIOLOGICALLY ACTIVE FILTERS: A CASE STUDY

EPA Science Inventory

Arsenic removal from drinking water is under investigation due to the U.S. Environmental Protection Agency’s new maximum contaminant level (MCL) of 0.010 mg As/L (was 0.050 mg/L) which took effect in January 2006. It is well known that As(III) (arsenite) is much more difficult t...

Temporal evolution modeling of hydraulic and water quality performance of permeable pavements

NASA Astrophysics Data System (ADS)

Huang, Jian; He, Jianxun; Valeo, Caterina; Chu, Angus

2016-02-01

A mathematical model for predicting hydraulic and water quality performance in both the short- and long-term is proposed based on field measurements for three types of permeable pavements: porous asphalt (PA), porous concrete (PC), and permeable inter-locking concrete pavers (PICP). The model was applied to three field-scale test sites in Calgary, Alberta, Canada. The model performance was assessed in terms of hydraulic parameters including time to peak, peak flow and water balance and a water quality variable (the removal rate of total suspended solids). A total of 20 simulated storm events were used for model calibration and verification processes. The proposed model can simulate the outflow hydrographs with a coefficient of determination (R2) ranging from 0.762 to 0.907, and normalized root-mean-square deviation (NRMSD) ranging from 13.78% to 17.83%. Comparison of the time to peak flow, peak flow, runoff volume and TSS removal rates between the measured and modeled values in model verification phase had a maximum difference of 11%. The results demonstrate that the proposed model is capable of capturing the temporal dynamics of the pavement performance. Therefore, the model has great potential as a practical modeling tool for permeable pavement design and performance assessment.

Nitrogen source effects on the denitrifying anaerobic methane oxidation culture and anaerobic ammonium oxidation bacteria enrichment process.

PubMed

Fu, Liang; Ding, Jing; Lu, Yong-Ze; Ding, Zhao-Wei; Zeng, Raymond J

2017-05-01

The co-culture system of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) has a potential application in wastewater treatment plant. This study explored the effects of permutation and combination of nitrate, nitrite, and ammonium on the culture enrichment from freshwater sediments. The co-existence of NO 3 - , NO 2 - , and NH 4 + shortened the enrichment time from 75 to 30 days and achieved a total nitrogen removal rate of 106.5 mg/L/day on day 132. Even though ammonium addition led to Anammox bacteria increase and a higher nitrogen removal rate, DAMO bacteria still dominated in different reactors with the highest proportion of 64.7% and the maximum abundance was 3.07 ± 0.25 × 10 8 copies/L (increased by five orders of magnitude) in the nitrite reactor. DAMO bacteria showed greater diversity in the nitrate reactor, and one was similar to M. oxyfera; DAMO bacteria in the nitrite reactor were relatively unified and similar to M. sinica. Interestingly, no DAMO archaea were found in the nitrate reactor. This study will improve the understanding of the impact of nitrogen source on DAMO and Anammox co-culture enrichment.

Developing a trend prediction model of subsurface damage for fixed-abrasive grinding of optics by cup wheels.

PubMed

Dong, Zhichao; Cheng, Haobo

2016-11-10

Fixed-abrasive grinding by cup wheels plays an important role in the production of precision optics. During cup wheel grinding, we strive for a large removal rate while maintaining fine integrity on the surface and subsurface layers (academically recognized as surface roughness and subsurface damage, respectively). This study develops a theoretical model used to predict the trend of subsurface damage of optics (with respect to various grinding parameters) in fixed-abrasive grinding by cup wheels. It is derived from the maximum undeformed chip thickness model, and it successfully correlates the pivotal parameters of cup wheel grinding with the subsurface damage depth. The efficiency of this model is then demonstrated by a set of experiments performed on a cup wheel grinding machine. In these experiments, the characteristics of subsurface damage are inspected by a wedge-polishing plus microscopic inspection method, revealing that the subsurface damage induced in cup wheel grinding is composed of craterlike morphologies and slender cracks, with depth ranging from ∼6.2 to ∼13.2  μm under the specified grinding parameters. With the help of the proposed model, an optimized grinding strategy is suggested for realizing fine subsurface integrity as well as high removal rate, which can alleviate the workload of subsequent lapping and polishing.

Comparison of semi-batch vs. continuously fed anaerobic bioreactors for the treatment of a high-strength, solids-rich pumpkin-processing wastewater.

PubMed

del Agua, Isabel; Usack, Joseph G; Angenent, Largus T

2015-01-01

The objective of this work was to compare two different high-rate anaerobic bioreactor configurations--the anaerobic sequencing batch reactor (ASBR) and the upflow anaerobic solid removal (UASR) reactor--for the treatment of a solid-rich organic wastewater with a high strength. The two, 4.5-L reactors were operated in parallel for close to 100 days under mesophilic conditions (37°C) with non-granular biomass by feeding a pumpkin wastewater with ∼4% solids. The organic loading rate of pumpkin wastewater was increased periodically to a maximum of 8 g COD L(-1) d(-1) by shortening the hydraulic retention time to 5.3 days. Compositional analysis of pumpkin wastewater revealed deficiencies in the trace metal cobalt and alkalinity. With supplementation, the ASBR outperformed the UASR reactor with total chemical oxygen demand (COD) removal efficiencies of 64% and 53%, respectively, achieving a methane yield of 0.27 and 0.20 L CH4 g(-1) COD fed to the ASBR and UASR, respectively. The better performance realized with the ASBR and this specific wastewater was attributed to its semi-batch, dynamic operating conditions rather than the continuous operating conditions of the UASR reactor.

Treatment of amoxicillin by O3/Fenton process in a rotating packed bed.

PubMed

Li, Mo; Zeng, Zequan; Li, Yingwen; Arowo, Moses; Chen, Jianfeng; Meng, Hong; Shao, Lei

2015-03-01

In this study, simulated amoxicillin wastewater was treated by the O3/Fenton process in a rotating packed bed (RPB) and the results were compared with the Fenton process and the O3 followed by Fenton (O3 + Fenton) process. The chemical oxygen demand (COD) removal rate and the ratio of 5-day biological oxygen demand to chemical oxygen demand (BOD5/COD) in the O3/Fenton process were approximately 17% and 26%, respectively, higher than those in the O3 + Fenton process with an initial pH of 3. The COD removal rate of the amoxicillin solution reached maximum at the Fe(II) concentration of 0.6 mM, temperature of 25 °C, rotation speed of 800 rpm and initial pH of 3. The BOD5/COD of the amoxicillin solution increased from 0 to 0.38 after the solution was treated by the O3/Fenton process. Analysis of the intermediates indicated that the pathway of amoxicillin degradation in the O3/Fenton process was similar to that in the O3 + Fenton process. Contrast experiment results showed that amoxicillin degradation was significantly intensified in the RPB. Copyright © 2014 Elsevier Ltd. All rights reserved.

[KTP (green light) laser for the treatment of benign prostatic hyperplasia. Preliminary evaluation].

PubMed

Coz, Fernando; Domenech, Alfredo

2007-09-01

Photoselective vaporization of benign prostatic hyperplasia (BPH) is a minimally invasive technique, consisting of vaporization of prostatic tissue by KTP green light laser with a power of 80 W. The purpose of this study was to describe our experience with this technique. KTP laser photoselective vaporization was performed in 18 patients, with lower obstructive uropathy secondary to benign prostatic hyperplasia at Santiago Military hospital from December 2005. Preoperative characteristics, postoperative results and complications were recorded. Mean prostatic volume was 55 cc (range: 24 to 78). Mean operating time was 83 minutes (range: 40 to 120). In sixteen patients, the Foley catheter was removed before 24 hours. The mean preoperative AUA score was 22 and decreased to 11.4 after 30 days. The mean maximum preoperative urine flow rate was 9 ml/s and increased to 18.2; 22.1; 22.5; 25.3 and 27.2 ml/s on days 1, 7, 14, 21 and 30, respectively. Only minor complications were observed: delayed removal of the Foley catheter (11.1%), dysuria (16.6%) and late haematuria (11.1%). KTP laser photoselective vaporization of BPH is a safe technique, that is easy to learn, with good short-term functional results, associated with low complication rate.

Autohydrogenotrophic denitrification of drinking water using a polyvinyl chloride hollow fiber membrane biofilm reactor.

PubMed

Zhang, Yanhao; Zhong, Fohua; Xia, Siqing; Wang, Xuejiang; Li, Jixiang

2009-10-15

A hollow fiber membrane biofilm reactor (MBfR) using polyvinyl chloride (PVC) hollow fiber was evaluated in removing nitrate form contaminated drinking water. During a 279-day operation period, the denitrification rate increased gradually with the increase of influent nitrate loading. The denitrification rate reached a maximum value of 414.72 g N/m(3)d (1.50 g N/m(2)d) at an influent NO(3)(-)-N concentration of 10mg/L and a hydraulic residence time of 37.5 min, and the influent nitrate was completely reduced. At the same time, the effluent quality analysis showed the headspace hydrogen content (3.0%) was lower enough to preclude having an explosive air. Under the condition of the influent nitrate surface loading of 1.04 g N/m(2)d, over 90% removal efficiencies of the total nitrogen and nitrate were achieved at the hydrogen pressure above 0.04 MPa. The results of denaturing gel gradient electrophoresis (DGGE), 16S rDNA gene sequence analysis, and hierarchical cluster analysis showed that the microbial community structures in MBfR were of low diversity, simple and stable at mature stages; and the beta-Proteobacteria, including Rhodocyclus, Hydrogenophaga, and beta-Proteobacteria HTCC379, probably play an important role in autohydrogenotrophic denitrification.

Surface Modified Pinecone Shaped Hierarchical Structure Fluorinated Mesocarbon Microbeads for Ultrafast Discharge and Improved Electrochemical Performances

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

Dai, Yang; Fang, Yuan; Cai, Sendan

2016-12-01

Among all primary lithium batteries, Li/CF x primary battery possesses the highest energy density of 2180 Wh kg -1. However, a key limitation is its poor rate capability because the cathode material CF x is intrinsically a poor electronic conductor. Here, we developed a so-called “doing subtraction” method to modify the pinecone shaped fluorinated mesocarbon microbead (F-MCMB). The modified fluorinated mesocarbon microbead (MF-MCMB), manifests the advantage of open-framed structure, possesses good electronic conductivity and removes transport barrier for lithium ions. Thus, high capacity performance and excellent rate capability without compromising capacity can be obtained. A capacity of 343 mAhg -1more » and a maximum power density of 54600 W kg -1 are realized at an ultrafast rate of 40 C (28A g -1). Additionally, the MF-MCMB cathode does not show any voltage delay even at 5C during the discharge, which is a remarkable improvement over the state-of-the-art CF xmaterials.« less

Hydrodynamic control of phytoplankton loss to the benthos in an estuarine environment

USGS Publications Warehouse

Jones, Nicole L.; Thompson, Janet K.; Arrigo, Kevin R.; Monismith, Stephen G.

2009-01-01

Field experiments were undertaken to measure the influence of hydrodynamics on the removal of phytoplankton by benthic grazers in Suisun Slough, North San Francisco Bay. Chlorophyll a concentration boundary layers were found over beds inhabited by the active suspension feeders Corbula amurensis and Corophium alienense and the passive suspension feeders Marenzellaria viridis and Laonome sp. Benthic losses of phytoplankton were estimated via both the control volume and the vertical flux approach, in which chlorophyll a concentration was used as a proxy for phytoplankton biomass. The rate of phytoplankton loss to the bed was positively correlated to the bed shear stress. The maximum rate of phytoplankton loss to the bed was five times larger than estimated by laboratory-derived pumping rates for the active suspension feeders. Reasons for this discrepancy are explored including a physical mechanism whereby phytoplankton is entrained in a near-bed fluff layer where aggregation is mediated by the presence of mucus produced by the infaunal community.

Hydrodynamic control of phytoplankton loss to the benthos in an estuarine environment

USGS Publications Warehouse

Jones, N.L.; Thompson, J.K.; Arrigo, K.R.; Monismith, Stephen G.

2009-01-01

Field experiments were undertaken to measure the influence of hydrodynamics on the removal of phytoplankton by benthic grazers in Suisun Slough, North San Francisco Bay. Chlorophyll a concentration boundary layers were found over beds inhabited by the active suspension feeders Corbula amurensis and Corophium alienense and the passive suspension feeders Marenzellaria viridis and Laonome sp. Benthic losses of phytoplankton were estimated via both the control volume and the vertical flux approach, in which chlorophyll a concentration was used as a proxy for phytoplankton biomass. The rate of phytoplankton loss to the bed was positively correlated to the bed shear stress. The maximum rate of phytoplankton loss to the bed was five times larger than estimated by laboratory-derived pumping rates for the active suspension feeders. Reasons for this discrepancy are explored including a physical mechanism whereby phytoplankton is entrained in a near-bed fluff layer where aggregation is mediated by the presence of mucus produced by the infaunal community. ?? 2009, by the American Society of Limnology and Oceanography, Inc.

Experimental binding of lead to a low cost on biosorbent: Nopal (Opuntia streptacantha).

PubMed

Miretzky, Patricia; Muñoz, Carolina; Carrillo-Chávez, Alejandro

2008-03-01

The use of nopal cladodes (Opuntia streptacantha) as raw material for Pb(2+) biosorption was investigated. Batch experiments were carried out to determine Pb(2+) sorption capacity and the efficiency of the sorption process under different pH, initial Pb(2+) and nopal biomass concentrations. The experimental data showed a good fit to Langmuir and Freundlich isotherms models. The maximum adsorption capacity for Pb(2+) was 0.14 mmol g(-1) with an efficiency higher than 94% (pH 5.0 and 2.5 g L(-1) nopal biomass). The Pb(2+) kinetics were best described by the pseudo-second-order rate model. The rate constant, the initial sorption rate and the equilibrium sorption capacity were determined. The practical implication of this study is the development of an effective and economic technology in which the nopal biomass did not undergo any chemical or physical pretreatment, which added to nopal abundance in Mexico and its low cost makes it a good option for Pb(2+) removal from contaminated waters.

Electromagnetic cyclotron-loss-cone instability associated with weakly relativistic electrons

NASA Technical Reports Server (NTRS)

Wong, H. K.; Wu, C. S.; Ke, F. J.; Schneider, R. S.; Ziebell, L. F.

1982-01-01

The amplification of fast extraordinary mode waves at frequencies very close to the electron cyclotron frequency, due to the presence of a population of energetic electrons with a loss-cone type distribution, is studied. Low-energy background electrons are included in the analysis. Two types of loss-cone distribution functions are considered, and it is found that the maximum growth rates for both distribution functions are of the same order of magnitude. When the thermal effects of the energetic electrons are included in the dispersion equation, the real frequencies of the waves are lower than those obtained by using the cold plasma approximation. This effect tends to enhance the growth rate. An idealized case including a parallel electric field such that the distribution function of the trapped energetic electrons is modified is also considered. It is assumed that the parallel electric field can remove the low-energy background electrons away from the source region of radiation. Both these effects increase the growth rate.

Effectiveness of Vegetated Drainage Ditches for Domestic Sewage Effluent Mitigation.

PubMed

Kumwimba, Mathieu Nsenga; Zhu, Bo

2017-05-01

Plant species have an important role in eco-ditches; however, the Michaelis-Menten kinetic parameters of nutrient uptake, growth rate and purification efficiency of ditch plants and their influences on domestic sewage treatment efficiency are still unclear. Growth rates of all nine species, but especially Lemna gibba, Cladophora and Myriophyllum verticillatum were best in undiluted domestic sewage as opposed to a mixture of domestic sewage. Performance of species to accumulate nutrients was not only species-specific, but was also affected by both sewage treatments. Removal efficiency of nutrients was dependent on both plant species and treatment. Uptake kinetic parameters were significantly affected by both nutrient form and plant species. The maximum uptake rate (Vmax) of NH 4 -N was higher than NO 3 -N. Similarly, Km values for NH 4 -N were greater than NO 3 -N. These results could be used to identify plants for sewage treatment efficiency and enhance water quality in eco-ditch treatment systems.

Using Central Composite Experimental Design to Optimize the Degradation of Tylosin from Aqueous Solution by Photo-Fenton Reaction

PubMed Central

Sarrai, Abd Elaziz; Hanini, Salah; Merzouk, Nachida Kasbadji; Tassalit, Djilali; Szabó, Tibor; Hernádi, Klára; Nagy, László

2016-01-01

The feasibility of the application of the Photo-Fenton process in the treatment of aqueous solution contaminated by Tylosin antibiotic was evaluated. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to evaluate and optimize the effect of hydrogen peroxide, ferrous ion concentration and initial pH as independent variables on the total organic carbon (TOC) removal as the response function. The interaction effects and optimal parameters were obtained by using MODDE software. The significance of the independent variables and their interactions was tested by means of analysis of variance (ANOVA) with a 95% confidence level. Results show that the concentration of the ferrous ion and pH were the main parameters affecting TOC removal, while peroxide concentration had a slight effect on the reaction. The optimum operating conditions to achieve maximum TOC removal were determined. The model prediction for maximum TOC removal was compared to the experimental result at optimal operating conditions. A good agreement between the model prediction and experimental results confirms the soundness of the developed model. PMID:28773551

Growth and heavy metal removal by Klebsiella aerogenes at different pH and temperature

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

Al-Shahwani, M.F.; Jazrawi, S.F.; Al-Rawi, E.H.

1984-01-01

A strain of Klebsiella aerogenes isolated from Rustamiyah Station for treatment of wastewater was examined for its ability to grow in a media supplemented with maximum tolerance concentrations of Pb/sup + +/, Zn/sup + +/, Ni/sup + +/, and Cd/sup + +/, separately, at different temperatures and initial pH. The results indicated that at 28/sup 0/C during the first 24 hr, Pb/sup + +/ and Ni/sup + +/ had no effect on the growth of the bacteria, while the presence of Zn/sup + +/ and Cd/sup + +/ decreased the cell count. The growth reached a maximum level after themore » second day and started to decrease gradually. The bacterial count at 37/sup 0/C was less than that at 28/sup 0/C. No bacterial multiplication occurred at 44/sup 0/C. There was little difference between heavy metal removal at 28 and 37/sup 0/C. At 44/sup 0/C, little removal took place. In general, slightly acidic or neutral medium was better for both bacterial growth and metal removal.« less

Removal of fluoride, arsenic and coliform bacteria by modified homemade filter media from drinking water.

PubMed

Devi, Rani; Alemayehu, Esayas; Singh, Vijender; Kumar, Ashok; Mengistie, Embialle

2008-05-01

An attempt was made to investigate the removal of fluoride, arsenic and coliform bacteria from drinking water using modified homemade filter media. Batch mode experimental study was conducted to test the efficiency of modified homemade filter for reduction of impurities under the operating condition of treatment time. The physico-chemical and biological analysis of water samples had been done before and after the treatment with filter media, using standard methods. Optimum operating treatment time was determined for maximum removal of these impurities by running the experiment for 2, 4, 6, 8, 10 and 12h, respectively. The maximum reduction of fluoride, arsenic and coliform bacteria in percentage was 85.60%, 93.07% and 100% and their residual values were 0.72 mg/l, 0.009 mg/l and 0 coliform cells/100ml, respectively after a treatment time of 10h. These residual values were under the permissible limits prescribed by WHO. Hence this could be a cheap, easy and an efficient technique for removal of fluoride, arsenic and coliform bacteria from drinking water.

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.

Potential of Staphylococcus xylosus strain for recovering nickel ions from aqueous solutions

NASA Astrophysics Data System (ADS)

Al-Gheethi, A.; Efaq, A. N.; Mohamed, R. M.; Abdel-Monem, M.; Amir Hashim, M.

2017-10-01

The potential of bacterial biomass for the biosorption of heavy metals has investigated extensively. However, the bacterial species exhibited different affinities toward the heavy metals ions based on their differences in cell wall characteristics, structure and physiological status (living or dead cells). In this study, the potential of living and dead cells of Staphylococcus xylosus 222W for removal nickel ions from aqueous solution as a function for physiological status, nickel and biomass concentrations, time, pH and temperature was investigated. The pre-treatment of bacterial cells was performed by the heating at 100 °C for 15 min. The removal experiments were conducted in the lab scale. The results revealed that the dead cells exhibited more efficiency in removing nickel ions than living cells at all investigated concentrations (2 to 10 mM). The biosorption efficiency (E %) increased with increasing in biomass cells to limit concentrations (0.1 to 1 g dry wt L-1). The maximum removal of nickel was 81.41 vs. 77.10 % by living and dead cells, respectively achieved after 9 and 10 hrs of the incubation period, respectively. The acidic conditions decrease the efficiency of metal removal, while the optimal removal was recorded at pH 8 for both biomass (living and dead cells). The maximum uptake capacity of S. xylosus 222W (living and dead cells) was recorded at 37oC, the percentage removed being 75.90 vs. 84.92 %, respectively. It can be concluded that S. xylosus 222W exhibited high potential and affinity to remove of nickel ions from aqueous solution.

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.

Iron coated pottery granules for arsenic removal from drinking water.

PubMed

Dong, Liangjie; Zinin, Pavel V; Cowen, James P; Ming, Li Chung

2009-09-15

A new media, iron coated pottery granules (ICPG) has been developed for As removal from drinking water. ICPG is a solid phase media that produces a stable Fe-Si surface complex for arsenic adsorption. Scanning electron microscopy (SEM) was used to document the physical attributes (grain size, pore size and distribution, surface roughness) of the ICPG media. Several advantages of the ICPG media such as (a) its granular structure, (b) its ability to absorb As via the F(0) coating on the granules' surface; (c) the inexpensive preparation process for the media from clay material make ICPG media a highly effective media for removing arsenic at normal pH. A column filtration test demonstrated that within the stability region (flow rate lower than 15L/h, EBCT >3 min), the concentration of As in the influent was always lower than 50 microg/L. The 2-week system ability test showed that the media consistently removed arsenic from test water to below the 5 microg/L level. The average removal efficiencies for total arsenic, As(III), and As(V) for a 2-week test period were 98%, 97%, and 99%, respectively, at an average flow rate of 4.1L/h and normal pH. Measurements of the Freundlich and Langmuir isotherms at normal pH show that the Freundlich constants of the ICPG are very close to those of ferric hydroxide, nanoscale zero-valent iron and much higher than those of nanocrystalline titanium dioxide. The parameter 1/n is smaller than 0.55 indicating a favorable adsorption process [K. Hristovski, A. Baumgardner, P. Westerhoff, Selecting metal oxide nanomaterials for arsenic removal in fixed bed columns: from nanopowders to aggregated nanoparticle media, J. Hazard. Mater. 147 (2007) 265-274]. The maximum adsorption capacity (q(e)) of the ICPG from the Langmuir isotherm is very close to that of nanoscale zero-valent indicating that zero-valent iron is involved in the process of the As removal from the water. The results of the toxicity characteristic leaching procedure (TCLP) analysis revealed that the media was non-hazardous, as shown by the ND (non-detectable) result for arsenic. The mechanism of As adsorption by ICPG has not been determined. Formation of Fe-Si complexes on the surface of the ICPG system may be responsible for the tight bonding of the As to the IGPC media.

Comparing the performance and operation stability of an SBR and MBBR for single-stage nitritation-anammox treating wastewater with high organic load.

PubMed

Lackner, Susanne; Horn, Harald

2013-01-01

Single stage nitritation-anammox reactors have gained increasing attention for their application in municipal and industrial wastewater treatment. The most commonly used system in municipal reject water treatment is at present the sequencing batch reactor (SBR), the moving-bed biofilm reactor (MBBR) is the second most common. However, little is known about their applicability to industrial wastewaters with high C/N ratios. This study presents a comparative approach to evaluate the performance of these two systems by changing the influent from reject water (C:N ratio 1:1) stepwise to an industrial wastewater (C:N ratio 3:1). An intentionally induced temperature drop that led to nitrite accumulation was also tested. The results showed that the MBBR (1.9 kg-N m(-3) d(-1)) was superior to the SBR (0.5 kg-N m(-3) d(-1)) with at maximum up to four times higher volumetric nitrogen removal rates. Both systems accumulated nitrite (> 100 mg-N L(-1)) during the temperature drop from 30 degrees C to as low as 18 degrees C (MBBR) and 20 degrees C (SBR), which subsequently resulted in almost complete loss in the removal capacities. However, the previous removal rates could be re-established in both systems within approximately 40 days. In comparison, the MBBR showed the more stable and higher performance even though higher nitrite concentrations (up to 500 mg-N L(-1)) were encountered. Overall, MBBR operation and handling was also easier and the system was more robust to disturbances compared to the SBR.

Start-up of the ananmmox process from the conventional activated sludge in a hybrid bioreactor.

PubMed

Duan, Xiumei; Zhou, Jiti; Qiao, Sen; Yin, Xin; Tian, Tian; Xu, Fangdi

2012-01-01

The anaerobic ammonium oxidation (anammox) process was successfully started up from conventional activated sludge using a hybrid bioreactor within 2 months. The average removal efficiencies of ammonia and nitrite were both over 80%, and the maximum total nitrogen removal rate of 1.85 kg N/(m3 x day) was obtained on day 362 with the initial sludge concentration of 0.7 g mixed liquor suspended solids (MLSS)/L. Scanning electron microscope (SEM) observation of the granular sludge in the hybrid reactor clearly showed a high degree of compactness and cell sphericity, and the cell size was quite uniform. Transmission electron microscope photos showed that cells were round or oval, the cellular diameter was 0.6-1.0 microm, and the percentage of the anammoxosome compartment was 51%-85% of the whole cell volume. Fluorescence in situ hybridization analysis (FISH) indicated that anammox bacteria became the dominant population in the community (accounting for more than 51% of total bacteria on day 250). Seven planctomycete 16S rRNA gene sequences were present in the 16S rRNA gene clone library generated from the biomass and affiliated to Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia sp., a new anammox species. In addition, the average effluent suspended solid (MLSS) concentrations of outlets I (above the non-woven carrier) and II (below the non-woven carrier) were 0.0009 and 0.0035 g/L, respectively. This showed that the non-woven carrier could catch the biomass effectively, which increased biomass and improved the nitrogen removal rate in the reactor.

44 CFR 208.12 - Maximum Pay Rate Table.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Maximum Pay Rate Table. 208... § 208.12 Maximum Pay Rate Table. (a) Purpose. This section establishes the process for creating and updating the Maximum Pay Rate Table (Table), and the Table's use to reimburse Affiliated Personnel (Task...

Effective swine wastewater treatment by combining microbial fuel cells with flocculation.

PubMed

Ding, Weijun; Cheng, Shaoan; Yu, Liliang; Huang, Haobin

2017-09-01

Microbial fuel cells (MFCs) provide a cost-effective method for treating swine wastewater treatment and simultaneously producing electricity, yet they need to be combined with other wastewater treatment processes to improve the effluent water quality. In this paper, we constructed single-chamber air-cathode MFCs with a compact configuration for nitrogen and COD removal and high electricity production and combined them with a low-cost flocculation process to discharge higher quality wastewater. We show that MFCs could remove ammonia at a rate of 269.2 ± 0.5 g m -3 d -1 (99.1± 0.1% ammonia removal efficiency) with a maximum power density of 37.5 W m -3 and 21.6% of coulombic efficiency at a 40:60 ratio of raw swine wastewater to denitrification effluent of swine wastewater. Up to 82.5 ± 0.5% COD could be removed with MFCs, from 2735 ± 15 mg L -1 to 480 ± 15 mg L -1 , and flocculation further reduced levels to 90 ± 1 mg L -1 for a 96.6 ± 0.2% overall COD removal efficiency of the combination technology. Cost analysis of the combined MFC and flocculation process showed a net economic benefit of $ 0.026 m -3 . In summary, this novel combination wastewater treatment method provides an effective way to treat swine wastewater to low pollutant levels in the effluent at low cost (a net gain). Copyright © 2017 Elsevier Ltd. All rights reserved.

Organic contaminant removal efficiency of sodium bentonite/clay (BC) mixtures in high permeability regions utilizing reclaimed wastewater: A meso-scale study

NASA Astrophysics Data System (ADS)

Xiao, Yang; Li, Yunkai; Ning, Zigong; Li, Pengxiang; Yang, Peiling; Liu, Chengcheng; Liu, Zhongwei; Xu, Feipeng; Hynds, Paul Dylan

2018-03-01

Wastewater reclamation now represents an effective measure for sustainable water resource management in arid regions, however wastewater components (organic micropollutants) may potentially impact local ecological and/or human health. Previous studies have shown that sodium bentonite/natural clay (BC) mixes may be used to effectively reduce riverbed infiltration in regions characterized by excessively high hydraulic conductivity. Accordingly, the current study sought to investigate the contaminant removal efficiency (Re) of several BC mass ratios in simulated dry riverbeds. Results indicate that the measured Re of NH4+-N, CODcr and BOD5 increased in concurrence with an increasing sodium bentonite ratio, up to a maximum Re of 97.4% (NH4+-N), 55.2% (CODcr), and 51.5% (BOD5). The primary contaminant removal site was shown to be the infiltration-reducing (BC) layer, accounting for approximately 40%, 60%, and 70% of NH4+-N, CODcr and BOD5 removal, respectively. Conversely, the removal efficiency of NO3-N was found to be low (<15%), while total phosphorous (TP) was found to actively leach from the infiltration-reduction layer, resulting in measured TP discharges 2.4-4.8 times those of initial infiltration values. The current study provides a technical baseline for the efficacy of sodium bentonite as an effective bi-functional material in areas utilizing reclaimed water i.e. concurrent reduction of infiltration rates (Function 1) and decontamination of reclaimed wastewater infiltration/recharge (Function 2). Findings indicate that sodium bentonite-clay mixes may represent a feasible alternative for managing recharge of non-potable aquifers with reclaimed wastewater.

The influence of low and high pressure levels during negative-pressure wound therapy on wound contraction and fluid evacuation.

PubMed

Borgquist, Ola; Ingemansson, Richard; Malmsjö, Malin

2011-02-01

Negative-pressure wound therapy promotes healing by drainage of excessive fluid and debris and by mechanical deformation of the wound. The most commonly used negative pressure, -125 mmHg, may cause pain and ischemia, and the pressure often needs to be reduced. The aim of the present study was to examine wound contraction and fluid removal at different levels of negative pressure. Peripheral wounds were created in 70-kg pigs. The immediate effects of negative-pressure wound therapy (-10 to -175 mmHg) on wound contraction and fluid removal were studied in eight pigs. The long-term effects on wound contraction were studied in eight additional pigs during 72 hours of negative-pressure wound therapy at -75 mmHg. Wound contraction and fluid removal increased gradually with increasing levels of negative pressure until reaching a steady state. Maximum wound contraction was observed at -75 mmHg. When negative-pressure wound therapy was discontinued, after 72 hours of therapy, the wound surface area was smaller than before therapy. Maximum wound fluid removal was observed at -125 mmHg. Negative-pressure wound therapy facilitates drainage of wound fluid and exudates and results in mechanical deformation of the wound edge tissue, which is known to stimulate granulation tissue formation. Maximum wound contraction is achieved already at -75 mmHg, and this may be a suitable pressure for most wounds. In wounds with large volumes of exudate, higher pressure levels may be needed for the initial treatment period.

Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles.

PubMed

Djanaguiraman, M; Boyle, D L; Welti, R; Jagadish, S V K; Prasad, P V V

2018-04-05

High temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d. Compared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system. Taken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.

The effect of leaf beetle herbivory on the fire behaviour of tamarisk (Tamarix ramosissima Lebed.)

USGS Publications Warehouse

Drus, Gail M.; Dudley, Tom L.; Brooks, Matthew L.; Matchett, John R.

2012-01-01

The non-native tree, Tamarix spp. has invaded desert riparian ecosystems in the south-western United States. Fire hazard has increased, as typically fire-resistant native vegetation is replaced by Tamarix. The tamarisk leaf beetle, Diorhabda carinulata Desbrochers, introduced for biological control, may affect fire behaviour by converting hydrated live Tamarix leaves and twigs into desiccated and dead fuels. This potentially increases fire hazard in the short term before native vegetation can be re-established. This study investigates how fire behaviour is altered in Tamarix fuels desiccated by Diorhabda herbivory at a Great Basin site, and by herbivory simulated by foliar herbicide at a Mojave Desert site. It also evaluates the influence of litter depth on fire intensity. Fire behaviour was measured with a fire intensity index that integrates temperature and duration (degree-minutes above 70°C), and with maximum temperature, duration, flame lengths, rates of spread and vegetation removal. Maximum temperature, flame length and rate of spread were enhanced by foliar desiccation of Tamarix at both sites. At only the Mojave site, there was a trend for desiccated trees to burn with greater fire intensity. At both sites, fire behaviour parameters were influenced to a greater degree by litter depth, vegetation density and drier and windier conditions than by foliar desiccation.

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

NASA Astrophysics Data System (ADS)

Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-10-01

A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ΔG and positive ΔH. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

Laser Propagation Research. Volume II. Gaseous and Particulate Characterization of the Atmosphere. App. A-3. Maximum, Mean and Minimum Values of Measured Gas Concentrations at NOP Site. App. A-4. Plots of Nephelometer and Aerosol Mass Monitor Data at Arky Site. App. A-5. Plots of Aerosol Mass Monitor Data at the NOP Site,

DTIC Science & Technology

1980-11-01

the rapid, partial removal or covering of contamination to reduce the radiation exposure rate as quickly as practicable to a point where priority work ...should be responsible for planning and implementing all decontamination activities. He could be a city en- gineer, public works engineer, industrial safety...responsibility for a local civil defense or emergency preparedness program. DisaterAnalysis - A review and determination of the extent of damage sufere bya

Evaluation program for secondary spacecraft cells: Acceptance test of Eagle-Picher 100 ampere-hour nickel-cadmium cells with auxiliary electrodes

NASA Technical Reports Server (NTRS)

Christy, D. E.

1972-01-01

Tests were conducted on a group of 29 cells for the purpose of removing from the life cycle program all cells found to have electrolyte leakage, internal shorts, low capacity, or inability to recover open circuit voltage above 1.150 volts after the cell short test. The test findings include the following: (1) All the cells exceeded the rated capacity of 103.5 to 119.0 ampere-hours on all three capacity checks. (2) All cells recovered above the 1.150 volt requirement after the cell short test. (3) The cells cannot be overcharged at the c/10 rate without exceeding 1.500 volts after approximately 12 to 13 hours of charge. (4) The resistance value necessary to provide maximum signal power across the auxiliary electrode was found to be 10 ohms. (5) One cell revealed a definite leak at the negative terminal.

System for and method of freezing biological tissue

NASA Technical Reports Server (NTRS)

Williams, T. E.; Cygnarowicz, T. A. (Inventor)

1978-01-01

Biological tissue is frozen while a polyethylene bag placed in abutting relationship against opposed walls of a pair of heaters. The bag and tissue are cooled with refrigerating gas at a time programmed rate at least equal to the maximum cooling rate needed at any time during the freezing process. The temperature of the bag, and hence of the tissue, is compared with a time programmed desired value for the tissue temperature to derive an error indication. The heater is activated in response to the error indication so that the temperature of the tissue follows the desired value for the time programmed tissue temperature. The tissue is heated to compensate for excessive cooling of the tissue as a result of the cooling by the refrigerating gas. In response to the error signal, the heater is deactivated while the latent heat of fusion is being removed from the tissue while the tissue is changing phase from liquid to solid.

O2/1 Delta/ emission in the day and night airglow of Venus

NASA Technical Reports Server (NTRS)

Connes, P.; Noxon, J. F.; Traub, W. A.; Carleton, N. P.

1979-01-01

An intense airglow from O2(1 Delta) at 1.27 microns on both the light and the dark sides of Venus has been detected by using a ground-based high-resolution Fourier-transform spectrometer. Both dayglow and nightglow are roughly 1,000 times brighter than the visible O2 nightglow found by Veneras 9 and 10 in 1975. The column emission rate of O2(1 Delta) from Venus is close to the rate at which fresh O atoms are produced from photolysis of CO2 on the day side. Formation of O2(1 Delta) is thus a major step in the removal of O atoms from the atmosphere, and dynamical processes must carry these atoms to the night side fast enough to yield a maximum density near 90 km, which is almost constant over the planet.

Research and development of low cost processes for integrated solar arrays. Final report, April 15, 1974--January 14, 1976

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

Graham, C.D.; Kulkarni, S.; Louis, E.

1976-05-01

Results of a program to study process routes leading to a low cost large area integrated silicon solar array manufacture for terrestrial applications are reported. Potential processes for the production of solar-grade silicon are evaluated from thermodynamic, economic, and technical feasibility points of view. Upgrading of the present arc-furnace process is found most favorable. Experimental studies of the Si/SiF/sub 4/ transport and purification process show considerable impurity removal and reasonable transport rates. Silicon deformation experiments indicate production of silicon sheet by rolling at 1350/sup 0/C is feasible. Significant recrystallization by strain-anneal technique has been observed. Experimental recrystallization studies using anmore » electron beam line source are discussed. A maximum recrystallization velocity of approximately 9 m/hr is calculated for silicon sheet. A comparative process rating technique based on detailed cost analysis is presented.« less

Biofiltration of xylene using wood charcoal as the biofilter media under transient and high loading conditions.

PubMed

Singh, Kiran; Giri, B S; Sahi, Amrita; Geed, S R; Kureel, M K; Singh, Sanjay; Dubey, S K; Rai, B N; Kumar, Surendra; Upadhyay, S N; Singh, R S

2017-10-01

The main objective of this study was to evaluate the performance of wood charcoal as biofilter media under transient and high loading condition. Biofiltration of xylene was investigated for 150days in a laboratory scale unit packed with wood charcoal and inoculated with mixed microbial culture at the xylene loading rates ranged from 12 to 553gm -3 h -1 . The kinetic analysis of the xylene revealed absence of substrate inhibition and possibility of achieving higher elimination under optimum condition. The pH, temperature, pressure drop and CO 2 production rate were regularly monitored during the experiments. Throughout experimental period, the removal efficiency (RE) was found to be in the range of 65-98.7% and the maximum elimination capacity (EC) was 405.7gm -3 h -1 . Molecular characterization results show Bacillus sp. as dominating microbial group in the biofilm. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Bosch process.

NASA Technical Reports Server (NTRS)

Meissner, H. P.; Reid, R. C.

1972-01-01

Many previous studies have been carried out to elucidate certain aspects of the Bosch process wherein CO2 is reacted over an iron catalyst to form carbon and water at temperatures around 1100 F. These results are assembled, and with the aid of new experimental data, are used to analyze the various reactions involved. It is shown that CO2 and H2 will not usually react to deposit carbon unless water is removed in a recycle loop. The critical importance of large catalyst areas is stressed relative to catalyst pretreatment processes. It is shown that in most operating Bosch reactions, mass transfer controls the rate of reaction, and it is suggested that the carbon filaments found are the expected result of such a rate limiting process. Typical recycle gas mixtures are considered, and maximum water yields are determined from various cases. A few suggestions are made to improve Bosch reaction performance, and a number of unresolved problems are noted.