Removal of toxic zinc from water/wastewater using eucalyptus seeds activated carbon: non-linear regression analysis.

PubMed

Senthil Kumar, Ponnusamy; Saravanan, Anbalagan; Anish Kumar, Kodyingil; Yashwanth, Ramesh; Visvesh, Sridharan

2016-08-01

In the present study, a novel activated carbon was prepared from low-cost eucalyptus seeds, which was utilised for the effectively removal of toxic zinc from the water/wastewater. The prepared adsorbent was studied by Fourier transform infrared spectroscopy and scanning electron microscopic characterisation studies. Adsorption process was experimentally performed for optimising the influencing factors such as adsorbent dosage, solution pH, contact time, initial zinc concentration, and temperature for the maximum removal of zinc from aqueous solution. Adsorption isotherm of zinc removal was ensued Freundlich model, and the kinetic model ensued pseudo-second order model. Langmuir monolayer adsorption capacity of the adsorbent for zinc removal was evaluated as 80.37 mg/g. The results of the thermodynamic studies suggested that the adsorption process was exothermic, thermodynamically feasible and impulsive process. Finally, a batch adsorber was planned to remove zinc from known volume and known concentration of wastewater using best obeyed model such as Freundlich. The experimental details showed the newly prepared material can be effectively utilised as a cheap material for the adsorption of toxic metal ions from the contaminated water.

Bacterial, viral and turbidity removal by intermittent slow sand filtration for household use in developing countries: experimental investigation and modeling.

PubMed

Jenkins, Marion W; Tiwari, Sangam K; Darby, Jeannie

2011-11-15

A two-factor three-block experimental design was developed to permit rigorous evaluation and modeling of the main effects and interactions of sand size (d(10) of 0.17 and 0.52 mm) and hydraulic head (10, 20, and 30 cm) on removal of fecal coliform (FC) bacteria, MS2 bacteriophage virus, and turbidity, under two batch operating modes ('long' and 'short') in intermittent slow sand filters (ISSFs). Long operation involved an overnight pause time between feeding of two successive 20 L batches (16 h average batch residence time (RT)). Short operation involved no pause between two 20 L batch feeds (5h average batch RT). Conditions tested were representative of those encountered in developing country field settings. Over a ten week period, the 18 experimental filters were fed river water augmented with wastewater (influent turbidity of 5.4-58.6 NTU) and maintained with the wet harrowing method. Linear mixed modeling allowed systematic estimates of the independent marginal effects of each independent variable on each performance outcome of interest while controlling for the effects of variations in a batch's actual residence time, days since maintenance, and influent turbidity. This is the first study in which simultaneous measurement of bacteria, viruses and turbidity removal at the batch level over an extended duration has been undertaken with a large number of replicate units to permit rigorous modeling of ISSF performance variability within and across a range of likely filter design configurations and operating conditions. On average, the experimental filters removed 1.40 log fecal coliform CFU (SD 0.40 log, N=249), 0.54 log MS2 PFU (SD 0.42 log, N=245) and 89.0 percent turbidity (SD 6.9 percent, N=263). Effluent turbidity averaged 1.24 NTU (SD 0.53 NTU, N=263) and always remained below 3 NTU. Under the best performing design configuration and operating mode (fine sand, 10 cm head, long operation, initial HLR of 0.01-0.03 m/h), mean 1.82 log removal of bacteria (98.5%) and mean 0.94 log removal of MS2 viruses (88.5%) were achieved. Results point to new recommendations regarding filter design, manufacture, and operation for implementing ISSFs in local settings in developing countries. Sand size emerged as a critical design factor on performance. A single layer of river sand used in this investigation demonstrated removals comparable to those reported for 2 layers of crushed sand. Pause time and increased residence time each emerged as highly beneficial for improving removal performance on all four outcomes. A relatively large and significant negative effect of influent turbidity on MS2 viral removal in the ISSF was measured in parallel with a much smaller weaker positive effect of influent turbidity on FC bacterial removal. Disturbance of the schmutzdecke by wet harrowing showed no effect on virus removal and a modest reductive effect on the bacterial and turbidity removal as measured 7 days or more after the disturbance. For existing coarse sand ISSFs, this research indicates that a reduction in batch feed volume, effectively reducing the operating head and increasing the pore:batch volume ratio, could improve their removal performance by increasing batch residence time. Copyright © 2011 Elsevier Ltd. All rights reserved.

How the novel integration of electrolysis in tidal flow constructed wetlands intensifies nutrient removal and odor control.

PubMed

Ju, Xinxin; Wu, Shubiao; Huang, Xu; Zhang, Yansheng; Dong, Renjie

2014-10-01

Intensified nutrient removal and odor control in a novel electrolysis-integrated tidal flow constructed wetland were evaluated. The average removal efficiencies of COD and NH4(+)-N were above 85% and 80% in the two experimental wetlands at influent COD concentration of 300 mg/L and ammonium nitrogen concentration of 60 mg/L regardless of electrolysis integration. Effluent nitrate concentration decreased from 2.5mg/L to 0.5mg/L with the reduction in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2). This result reveals the important role of current intensity in nitrogen transformation. Owing to the ferrous and ferric iron coagulant formed through the electro-dissolution of the iron anode, electrolysis integration not only exerted a positive effect on phosphorus removal but also effectively inhibited sulfide accumulation for odor control. Although electrolysis operation enhanced nutrient removal and promoted the emission of CH4, no significant difference was observed in the microbial communities and abundance of the two experimental wetlands. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of time on dyeing wastewater treatment

NASA Astrophysics Data System (ADS)

Ye, Tingjin; Chen, Xin; Xu, Zizhen; Chen, Xiaogang; Shi, Liang; He, Lingfeng; Zhang, Yongli

2018-03-01

The preparation of carboxymethylchitosan wrapping fly-ash adsorbent using high temperature activated fly ash and sodium carboxymethyl chitosan (CWF), as with the iron-carbon micro-electrolysis process simulation and actual printing and dyeing wastewater. The effects of mixing time and static time on decolorization ratio, COD removing rate and turbidness removing rate were investigated. The experimental results show that the wastewater stirring times on the decolorization rate and COD removal rate and turbidity removal rate influence, with increasing of the stirring time, three showed a downward trend, and reached the peak at 10 min time; wastewater time on the decolorization ratio and COD removing efficiency and turbidness removing rate influence, along with standing time increase, three who declined and reached the maximum in 30min time.

Preliminary screening oxidative degradation methyl orange using ozone/ persulfate

NASA Astrophysics Data System (ADS)

Aqilah Razali, Nur; Zulzikrami Azner Abidin, Che; An, Ong Soon; Ridwan, Fahmi Muhammad; Haqi Ibrahim, Abdul; Nasuha Sabri, Siti; Huan Kow, Su

2018-03-01

The present study focusing on the performances of advanced oxidation process by using ozonation method towards Methyl Orange based on the efficiency of colour removal and Chemical Oxygen Demand (COD) removal. Factorial design with response surface methodology (RSM) was used to evaluate the interaction between operational conditions, such as pH, initial concentration, contact time and persulfate dosage to obtain the optimum range conditions using a semi-batch reactor. The range of independent variables investigated were pH (3-11), initial concentration (100-500mg/L), contact time (10-50min) and persulfate dosage (20-100mM) while the response variables were colour removal and COD removal of Methyl Orange. The experimental results and statistical analysis showed all the parameters were significant. Thus, from this findings, optimization of operational conditions that had been suggested from the ozone/persulfate RSM analysis were (pH 3, 100 mg/L, 50min, 60mM) that would be produced 99% Colour Removal and 80% COD Removal and help in promoting an efficient ozonation process. The effect list data that showed the most contributed effects to increase the percentages of colour removal were pH and persulfate dosage whereas the contact time and initial concentration had the highest positive effects on the COD removal. Other than that, the interaction between pH, contact time and persulfate dosage were found to be the most influencing interaction. Therefore the least influencing interaction was interaction between persulfate dosage and pH. In this study, the correlation coefficient value R2 for colour removal and COD removal of Methyl Orange were R2= 0.9976 and R2= 0.9924 which suggested a good fit of the first-order regression model with the experimental data.

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.

Marcescent corollas as functional structures: effects on the fecundity of two insect-pollinated plants

PubMed Central

Herrera, Carlos M.

2010-01-01

Background and aims Persistence of withered corollas after anthesis (‘corolla marcescence’) is widespread in angiosperms, yet its functional significance does not seem to have been explored for any species. This note reports the results of experiments assessing the fecundity effects of marcescent corollas in two southern Spanish insect-pollinated plants, Lavandula latifolia (Lamiaceae) and Viola cazorlensis (Violaceae). Methods The effect of marcescent corollas on seed production was evaluated experimentally on wild-growing plants. Newly open flowers were randomly assigned to either control or treatment groups in experimental plants. After anthesis, withered corollas of treatment flowers were removed and those in control flowers were left in place. Fruits produced by treatment and control flowers were collected shortly before dehiscence and the number of seeds counted. Key Results In V. cazorlensis, removal of withered corollas had no effect on percentage of fruit set, but mean seeds per fruit increased from 9·5 to 11·4. In L. latifolia, corolla removal had no effect on the number of seeds per fruit, but reduced the proportion of flowers ripening fruit from 60 % to 40 %. The detrimental effect of corolla removal on L. latifolia fecundity resulted from the drastic increase in fruit infestation by seed-predatory cecidomyiid larvae, which occurred in 4 % and 34 % of control and treatment fruits, respectively. Conclusions Because of their potential effects on plant fecundity, marcescent corollas should not be dismissed a priori as biologically irrelevant leftovers from past floral functions. The simplicity of the experimental layout required to test for short-term fecundity effects of corolla marcescence should help to achieve a better understanding of the ecological and evolutionary correlates of this widespread but poorly understood trait. PMID:20870656

Marcescent corollas as functional structures: effects on the fecundity of two insect-pollinated plants.

PubMed

Herrera, Carlos M

2010-10-01

Persistence of withered corollas after anthesis ('corolla marcescence') is widespread in angiosperms, yet its functional significance does not seem to have been explored for any species. This note reports the results of experiments assessing the fecundity effects of marcescent corollas in two southern Spanish insect-pollinated plants, Lavandula latifolia (Lamiaceae) and Viola cazorlensis (Violaceae). The effect of marcescent corollas on seed production was evaluated experimentally on wild-growing plants. Newly open flowers were randomly assigned to either control or treatment groups in experimental plants. After anthesis, withered corollas of treatment flowers were removed and those in control flowers were left in place. Fruits produced by treatment and control flowers were collected shortly before dehiscence and the number of seeds counted. In V. cazorlensis, removal of withered corollas had no effect on percentage of fruit set, but mean seeds per fruit increased from 9·5 to 11·4. In L. latifolia, corolla removal had no effect on the number of seeds per fruit, but reduced the proportion of flowers ripening fruit from 60 % to 40 %. The detrimental effect of corolla removal on L. latifolia fecundity resulted from the drastic increase in fruit infestation by seed-predatory cecidomyiid larvae, which occurred in 4 % and 34 % of control and treatment fruits, respectively. Because of their potential effects on plant fecundity, marcescent corollas should not be dismissed a priori as biologically irrelevant leftovers from past floral functions. The simplicity of the experimental layout required to test for short-term fecundity effects of corolla marcescence should help to achieve a better understanding of the ecological and evolutionary correlates of this widespread but poorly understood trait.

Theoretical Analysis and Experimental Study on the Coating Removal from Passenger-Vehicle Plastics for Recycling by Using Water Jet Technology

NASA Astrophysics Data System (ADS)

Zhang, Hongshen; Chen, Ming

2015-11-01

The recovery and utilization of automotive plastics are a global concern because of the increasing number of end-of-life vehicles. In-depth studies on technologies for the removal of coatings from automotive plastics can contribute to the high value-added levels of the recycling and utilization of automotive plastic. The liquid waste generated by removing chemical paint by using traditional methods is difficult to handle and readily produces secondary pollution. Therefore, new, clean, and highly efficient techniques of paint removal must be developed. In this article, a method of coating removal from passenger-vehicle plastics was generated based on high-pressure water jet technology to facilitate the recycling of these plastics. The established technology was theoretically analyzed, numerically simulated, and experimentally studied. The high-pressure water jet equipment for the removal of automotive-plastic coatings was constructed through research and testing, and the detailed experiments on coating removal rate were performed by using this equipment. The results showed that high-pressure water jet technology can effectively remove coatings on the surfaces of passenger-vehicle plastics. The research also revealed that the coating removal rate increased as jet pressure ( P) increased and then decreased when jet moving speed ( Vn) increased. The rate decreased as the distance from nozzle to work piece ( S nw ) and the nozzle angle ( Φ) increased. The mathematical model for the rate of removal of coatings from bumper surfaces by water jet was derived based on the experiment data and can effectively predict coating removal rate under different operating conditions.

Study on removal efficiency of nitrogen and phosphorus from agricultural wastewater by subsurface flow constructed wetland

NASA Astrophysics Data System (ADS)

Ling, Zhen; Li, Jie

2018-03-01

Subsurface Flow Constructed Wetland Plant 5 kinds of perennial herbs, there are Canna, Water onion, Iris, Calamus, Reed. Foucs on Subsurface Flow Constructed Wetlands on agricultural wastewater nitrogen and phosphorus removal effect. Research results: Different plants TP removal efficiency from high to low is Iris> reed> calamus> water onion> canna.And TN removal efficiency from high to low is reed> water onion> iris> calamus> canna. Compared with the blank test land, Wetland plants improves TN removal and TP removal is higher than TN. Wetland plants can reduce the PH of experimental water.

Effects of weak electromagnetic fields on Escherichia coli and Staphylococcus aureus

NASA Astrophysics Data System (ADS)

Smith, Derek A.

Previous studies of electromagnetic field effects on bacteria are examined, and new experimental procedures and their results are discussed. Experimental samples of Escherichia coli and Staphylococcus aureus were prepared in different conditions, and measurements of optical density were used to track growth rates after removing the samples from their associated experimental environments. Experimental environments varied in magnetic field intensities and frequencies, including a control environment of minimal field intensity. Plots of experimental data sets and their associated averages are used to visualize the experimental outcomes, and differences in growth patterns are evaluated. Results are then used to hypothesize the mechanisms and consequences of the potentially observed field effects.

Effect of Permanganate Preoxidation to Natural Organic Matter and Disinfection by-Products Formation Potential Removal

NASA Astrophysics Data System (ADS)

Hidayah, E. N.; Yeh, H. H.

2018-01-01

Laboratory scale experiments was conducted to examine effect of permanganate (KMnO4) peroxidation in characterizing and to remove natural organic matter (NOM) in source water. The experimental results shows that increasing permanganate dosage could decreased aromatic matter, as indicated by decreasing UV254 and SUVA value about 23% and 28%, respectively. It seems that permanganate preoxidation caused the breakdown of high molecular weight (MW) organics into low MW ones, as represented by increasing NPDOC about 10%. Further, disinfection by-products formation potential (DBPFP) in terms of trihalomethanes formation potential (THMFP) and haloacetic acid formation potential (HAAP) decreased about 15% and 23%, respectively. HAAFP removal is higher than THMFP removal and that DPBFP removal is consistent with UV254 and NPDOC removal.

Magnesium incorporated bentonite clay for defluoridation of drinking water.

PubMed

Thakre, Dilip; Rayalu, Sadhana; Kawade, Raju; Meshram, Siddharth; Subrt, J; Labhsetwar, Nitin

2010-08-15

Low cost bentonite clay was chemically modified using magnesium chloride in order to enhance its fluoride removal capacity. The magnesium incorporated bentonite (MB) was characterized by using XRD and SEM techniques. Batch adsorption experiments were conducted to study and optimize various operational parameters such as adsorbent dose, contact time, pH, effect of co-ions and initial fluoride concentration. It was observed that the MB works effectively over wide range of pH and showed a maximum fluoride removal capacity of 2.26 mgg(-1) at an initial fluoride concentration of 5 mg L(-1), which is much better than the unmodified bentonite. The experimental data fitted well into Langmuir adsorption isotherm and follows pseudo-first-order kinetics. Thermodynamic study suggests that fluoride adsorption on MB is reasonably spontaneous and an endothermic process. MB showed significantly high fluoride removal in synthetic water as compared to field water. Desorption study of MB suggest that almost all the loaded fluoride was desorbed ( approximately 97%) using 1M NaOH solution however maximum fluoride removal decreases from 95.47 to 73 (%) after regeneration. From the experimental results, it may be inferred that chemical modification enhances the fluoride removal efficiency of bentonite and it works as an effective adsorbent for defluoridation of water. Copyright 2010 Elsevier B.V. All rights reserved.

Optimization of the ultrasonic assisted removal of methylene blue by gold nanoparticles loaded on activated carbon using experimental design methodology.

PubMed

Roosta, M; Ghaedi, M; Daneshfar, A; Sahraei, R; Asghari, A

2014-01-01

The present study was focused on the removal of methylene blue (MB) from aqueous solution by ultrasound-assisted adsorption onto the gold nanoparticles loaded on activated carbon (Au-NP-AC). This nanomaterial was characterized using different techniques such as SEM, XRD, and BET. The effects of variables such as pH, initial dye concentration, adsorbent dosage (g), temperature and sonication time (min) on MB removal were studied and using central composite design (CCD) and the optimum experimental conditions were found with desirability function (DF) combined response surface methodology (RSM). Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Analysis of experimental adsorption data to various kinetic models such as pseudo-first and second order, Elovich and intraparticle diffusion models show the applicability of the second-order equation model. The small amount of proposed adsorbent (0.01 g) is applicable for successful removal of MB (RE>95%) in short time (1.6 min) with high adsorption capacity (104-185 mg g(-1)). Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of long-term exposure on LDEF fastener assemblies

NASA Astrophysics Data System (ADS)

Spear, Steve; Dursch, Harry

1992-09-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Effects of long-term exposure on LDEF fastener assemblies

NASA Technical Reports Server (NTRS)

Spear, Steve; Dursch, Harry

1992-01-01

This presentation summarizes the Systems Special Investigations Group (SIG) findings from testing and analysis of fastener assemblies used on the Long Duration Exposure Facility (LDEF) structure, the tray mounting clamps, and by the various experimenters. The LDEF deintegration team and several experimenters noted severe fastener damage and hardware removal difficulties during post-flight activities. The System SIG has investigated all reported instances, and in all cases examined to date, the difficulties were attributed to galling during installation or post-flight removal. To date, no evidence of coldwelding was found. Correct selection of materials and lubricants as well as proper mechanical procedures is essential to ensure successful on-orbit or post-flight installation and removal of hardware.

Effectiveness of litter removal in preventing mortality of yellow barked ponderosa pine in northern Arizona

Treesearch

James F. Fowler; Carolyn H. Sieg; Linda Wadleigh; Sally Haase

2007-01-01

Removal of deep litter and duff from the base of mature southwestern ponderosa pine trees is commonly recommended to reduce mortality following prescribed burns, but experimental studies that quantify the effectiveness of such practices in reducing mortality are lacking. Following a pilot study, on each of four sites in northern Arizona we monitored 15-16 sets of 8...

Effectiveness of litter removal to prevent cambial kill-caused mortality in northern Arizona ponderosa pine

Treesearch

James F. Fowler; Carolyn Hull Sieg; Linda L. Wadleigh

2010-01-01

Removal of deep litter and duff from the base of mature southwestern ponderosa pine (Pinus ponderosa Laws.) is commonly recommended to reduce mortality after prescribed burns, but experimental studies that quantify the effectiveness of such practices in reducing mortality are lacking. After a pilot study on each of four sites in northern Arizona, we monitored 15-16...

Spatial ecology of predator-prey interactions: corridors and patch shape influence seed predation.

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

J. L . Orrock; B. J. Danielson; M. J. Burns

2003-02-03

J.L. Orrock, B.J. Danielson, M.J. Burns, and D.J. Levey. 2003. Spatial ecology of predator-prey interactions: corridors and patch shape influence seed predation. Ecology, 84(10):2589-2599. Abstract: Corridors that connect patches of disjunct habitat may be promising tools for mediating the negative impacts of habitat fragmentation, but little is known about how corridors affect ecological interactions. In eight 12-ha experimental landscapes, we examined how corridors affect the impact of invertebrate, rodent, and avian seed predators on pokeweed, Phytolacca americana. Over 13 months in 2000 and 2001, we quantified the effects of patch shape, connectivity, and predator type on the number of seedsmore » germinating in the field (germinants), seed removal, and the viability of remaining seeds. Corridors did not affect the number of P. americana germinants in experimental exclosures or the viability of seeds remaining in exclosures. However, corridors affected the removal of seeds in a predator-specific manner: invertebrates removed more seeds in unconnected patches, whereas rodents removed more seeds in connected patches. Seed removal by birds was similar in connected and unconnected patches. Total seed removal by all seed predators was not affected by corridors, because invertebrates removed more seeds where rodents removed fewer seeds, and vice versa. Overall, seed predation signi®cantly reduced the number and viability of remaining seeds, and reduced the number of germinants in 2000 but not in 2001. The abundance of naturally occurring P. americana plants in our experimental patches in 2000 decreased with increasing seed removal from exclosures but was not related to viability or germinants in 2000, suggesting that seed removal may shape the distribution and abundance of this species. Complementary patterns of seed removal by rodents and invertebrates suggest that corridors alter the effects of these predator taxa by changing the relative amounts of edge and core (nonedge) habitats in a patch. Because invertebrates and rodents do not completely overlap in the seeds they consume, corridors may change predation pressure on seeds that are primarily consumed by one predator type, with potential consequences for the composition of plant and seed predator communities.« less

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

[Optimization Study on the Nitrogen and Phosphorus Removal of Modified Two- sludge System Under the Condition of Low Carbon Source].

PubMed

Yang, Wei-qiang; Wang, Dong-bo; Li, Xiao-ming; Yang, Qi; Xu, Qiu-xiang; Zhang, Zhi-bei; Li, Zhi-jun; Xiang, Hai-hong; Wang, Ya-li; Sun, Jian

2016-04-15

This paper explored the method of resolving insufficient carbon source in urban sewage by comparing and analyzing denitrification and phosphorus removal (NPR) effect between modified two-sludge system and traditional anaerobic-aerobic-anoxic process under the condition of low carbon source wastewater. The modified two-sludge system was the experimental reactor, which was optimized by adding two stages of micro-aeration (aeration rate 0.5 L · mm⁻¹) in the anoxic period of the original two-sludge system, and multi-stage anaerobic-aerobic-anoxic SBR was the control reactor. When the influent COD, ammonia nitrogen, SOP concentration were respectively 200, 35, 10 mg · L⁻¹, the NPR effect of the experimental reactor was hetter than that of thecontrol reactor with the removal efficiency of TN being 94.8% vs 60.9%, and TP removal being 96.5% vs 75%, respectively. The effluent SOP, ammonia, TN concentration of the experimental reactor were 0.35, 0.50, 1.82 mg · L⁻¹, respectively, which could fully meet the first class of A standard of the Pollutants Emission Standard of Urban Wastewater Treatment Firm (GB 18918-2002). Using the optimized treatment process, the largest amounts of nitrogen and phosphorus removal per unit carbon source (as COD) were 0.17 g · g⁻¹ and 0.048 g · g⁻¹ respectively, which could furthest solve the lower carbon concentration in current municipal wastewater.

Efficiencies of multilayer infiltration systems for the removal of urban runoff pollutants.

PubMed

Hou, Lizhu; Liu, Fang; Feng, Chuanping; Wan, Li

2013-01-01

Current rates of urban development will result in water runoff becoming a major complication of urban water pollution. To address the worsening situation regarding water resource shortage and pollution, novel multilayer infiltration systems were designed and their effectiveness for removing pollutants in urban runoff tested experimentally. The multilayer infiltration systems effectively removed most pollutants, including organic matter (chemical oxygen demand (CODCr)), total nitrogen (TN), ammonia-nitrogen (NH4(+)-N) and total phosphorus (TP). CODCr, TN, NH4(+)-N, and TP were reduced by 68.67, 23.98, 82.66 and 92.11%, respectively. The main mechanism for nitrogen removal was biological nitrogen removal through nitrification and denitrification. Phosphorus in the urban runoff was removed mainly by fixation processes in the soil, such as adsorption and chemical precipitation. The results indicate that the proposed novel system has potential for removal of pollutants from urban runoff and subsequent reuse of the treated water.

78 FR 44588 - Experimental Removal of Barred Owls To Benefit Threatened Northern Spotted Owls; Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-24

... experimental design, duration of the study, and the method of barred owl removal. Background The Service listed... and nonlethal), and the type of experimental design (demography vs. occupancy). All action...-FF01E00000] Experimental Removal of Barred Owls To Benefit Threatened Northern Spotted Owls; Final...

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

PubMed Central

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

2013-01-01

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

Microbial biomass and bacterial functional diversity in forest soils: effects of organic matter removal, compaction, and vegetation control

Treesearch

Qingchao Li; H. Lee Allen; Arthur G. Wollum

2004-01-01

The effects of organic matter removal, soil compaction, and vegetation control on soil microbial biomass carbon, nitrogen, C-to-N ratio, and functional diversity were examined in a 6-year loblolly pine plantation on a Coastal Plain site in eastern North Carolina, USA. This experimental plantation was established as part of the US Forest Service's Long Term Soil...

Hydrogen peroxide modification enhances the ability of biochar (hydrochar) produced from hydrothermal carbonization of peanut hull to remove aqueous heavy metals: Batch and column tests

USDA-ARS?s Scientific Manuscript database

Experimental and modeling investigations were conducted to examine the effect of hydrogen peroxide treatment on hydrothermally produced biochar (hydrochar) from peanut hull to remove aqueous heavy metals. Characterization measurements showed that hydrogen peroxide modification increased the oxygen-c...

Mesquite removal and mulching impacts on herbage production on a semidesert grass-shrub rangeland

Treesearch

Stacy Pease; Peter F. Ffolliott; Gerald J. Gottfried; Leonard F. DeBano

2006-01-01

The objectives of our study were to determining the effects of velvet mesquite (Prosopis velutina) removal, control of the resulting basal sprouts, and mulching treatments on herbage production (standing biomass) and selected soil chemicals (nutrients) shown to affect herbage production on the Santa Rita Experimental Range. Mesquite control...

The chemo-mechanical effect of cutting fluid on material removal in diamond scribing of silicon

NASA Astrophysics Data System (ADS)

Kumar, Arkadeep; Melkote, Shreyes N.

2017-07-01

The mechanical integrity of silicon wafers cut by diamond wire sawing depends on the damage (e.g., micro-cracks) caused by the cutting process. The damage type and extent depends on the material removal mode, i.e., ductile or brittle. This paper investigates the effect of cutting fluid on the mode of material removal in diamond scribing of single crystal silicon, which simulates the material removal process in diamond wire sawing of silicon wafers. We conducted scribing experiments with a diamond tipped indenter in the absence (dry) and in the presence of a water-based cutting fluid. We found that the cutting mode is more ductile when scribing in the presence of cutting fluid compared to dry scribing. We explain the experimental observations by the chemo-mechanical effect of the cutting fluid on silicon, which lowers its hardness and promotes ductile mode material removal.

Model of the material removal function and an experimental study on a magnetorheological finishing process using a small ball-end permanent-magnet polishing head.

PubMed

Chen, Mingjun; Liu, Henan; Cheng, Jian; Yu, Bo; Fang, Zhen

2017-07-01

In order to achieve the deterministic finishing of optical components with concave surfaces of a curvature radius less than 10 mm, a novel magnetorheological finishing (MRF) process using a small ball-end permanent-magnet polishing head with a diameter of 4 mm is introduced. The characteristics of material removal in the proposed MRF process are studied. The model of the material removal function for the proposed MRF process is established based on the three-dimensional hydrodynamics analysis and Preston's equation. The shear stress on the workpiece surface is calculated by means of resolving the presented mathematical model using a numerical solution method. The analysis result reveals that the material removal in the proposed MRF process shows a positive dependence on shear stress. Experimental research is conducted to investigate the effect of processing parameters on the material removal rate and improve the surface accuracy of a typical rotational symmetrical optical component. The experimental results show that the surface accuracy of the finished component of K9 glass material has been improved to 0.14 μm (PV) from the initial 0.8 μm (PV), and the finished surface roughness Ra is 0.0024 μm. It indicates that the proposed MRF process can be used to achieve the deterministic removal of surface material and perform the nanofinishing of small curvature radius concave surfaces.

Importance of clothing removal in scalds.

PubMed

Lau, Edgar Y K; Tam, Yvonne Y W; Chiu, T W

2016-04-01

To test the hypothesis that prompt removal of clothing after scalds lessens the severity of injury. This experimental study and case series was carried out in the Burn Centre of a tertiary hospital in Hong Kong. An experimental burn model using Allevyn (Smith & Nephew Medical Limited, Hull, England) as a skin substitute was designed to test the effect of delayed clothing removal on skin temperature using hot water and congee. Data of patients admitted with scalding by congee over a 10-year period (January 2005 to December 2014) were also studied. A significant reduction in the temperature of the skin model following a hot water scald was detected only if clothing was removed within the first 10 seconds of injury. With congee scalds, the temperature of the skin model progressively increased with further delay in clothing removal. During the study period, 35 patients were admitted with congee scalds to our unit via the emergency department. The majority were children. Definite conclusions supporting the importance of clothing removal could not be drawn due to our small sample size. Nonetheless, our data suggest that appropriate prehospital burn management can reduce patient morbidity. Prompt removal of clothing after scalding by congee may reduce post-burn morbidity.

Effectiveness of Hand Sanitizers with and without Organic Acids for Removal of Rhinovirus from Hands ▿

PubMed Central

Turner, Ronald B.; Fuls, Janice L.; Rodgers, Nancy D.

2010-01-01

These studies evaluated the effectiveness of ethanol hand sanitizers with or without organic acids to remove detectable rhinovirus from the hands and prevent experimental rhinovirus infection. Ethanol hand sanitizers were significantly more effective than hand washing with soap and water. The addition of organic acids to the ethanol provided residual virucidal activity that persisted for at least 4 h. Whether these treatments will reduce rhinovirus infection in the natural setting remains to be determined. PMID:20047916

Experimental design approach applied to the elimination of crystal violet in water by electrocoagulation with Fe or Al electrodes.

PubMed

Durango-Usuga, Paula; Guzmán-Duque, Fernando; Mosteo, Rosa; Vazquez, Mario V; Peñuela, Gustavo; Torres-Palma, Ricardo A

2010-07-15

An experimental design methodology was applied to evaluate the decolourization of crystal violet (CV) dye by electrocoagulation using iron or aluminium electrodes. The effects and interactions of four parameters, initial pH (3-9), current density (6-28 A m(-2)), substrate concentration (50-200 mg L(-1)) and supporting electrolyte concentration (284-1420 mg L(-1) of Na(2)SO(4)), were optimized and evaluated. Although the results using iron anodes were better than for aluminium, the effects and interactions of the studied parameters were quite similar. With a confidence level of 95%, initial pH and supporting electrolyte concentration showed limited effects on the removal rate of CV, whereas current density, pollutant concentration and the interaction of both were significant. Reduced models taking into account significant variables and interactions between variables have shown good correlations with the experimental results. Under optimal conditions, almost complete removal of CV and chemical oxygen demand were obtained after electrocoagulation for 5 and 30 min, using iron and aluminium electrodes, respectively. These results indicate that electrocoagulation with iron anodes is a rapid, economical and effective alternative to the complete removal of CV in waters. Evolutions of pH and residual iron or aluminium concentrations in solution are also discussed. 2010 Elsevier B.V. All rights reserved.

Adsorption of SO2 and NO from incineration flue gas onto activated carbon fibers.

PubMed

Liu, Zhen-Shu

2008-11-01

Activated carbon fibers (ACFs) were used to remove SO2 and NO from incineration flue gas. Three types of ACFs in their origin state and after pretreatment with HNO3, NaOH, and KOH were investigated. The removal efficiencies of SO2 and NO were determined experimentally at defined SO2 and NO concentrations and at temperatures of 150, 200 and 260 degrees C. Experimental results indicated that the removal efficiencies of SO2 and NO using the original ACFs were < 56% and < 27%, respectively. All ACFs modified with HNO3, NaOH, and KOH solution could increase the removal efficiencies of SO(2) and NO. The mesopore volumes and functional groups of ACFs are important in determining the removal of SO2 and NO. When the mesopore volumes of the ACFs are insufficient for removing SO2 and NO, the functional groups on the ACFs are not important in determining the removal of SO2 and NO. On the contrary, the effects of the functional groups on the removal of SO2 and NO are more important than the mesopore volumes as the amount of mesopores on the ACFs is sufficient to remove SO2 and NO. Moreover, the removal efficiencies of SO2 and NO were greatest at 200 degrees C. When the inlet concentration of SO2 increased to 600 ppm, the removal efficiency of SO2 increased slightly and the removal efficiency of NO decreased.

Effect of clarification process on the removal of pesticide residues in red wine and comparison with white wine.

PubMed

Doulia, Danae S; Anagnos, Efstathios K; Liapis, Konstantinos S; Klimentzos, Demetrios A

2018-04-30

The aim of this study was to determine the potential of seven clarifying agents to remove pesticides in red wine. The presence of pesticides in wine consists a great problem for winemakers and therefore, results on pesticide removal by clarification are very useful for taking a decision on the appropriate adsorbent. The selection of an efficient adsorbent can be based on data correlating pesticide removal in red wine to pesticides' properties, given the great number and variety of pesticides used. So, this experimental work is focused on the collection of results with regard to pesticide removal by clarification using a great number of pesticides and fining agents. A Greek red wine, fortified with single solutions and mixtures of 23 or 9 pesticides was studied. The seven fining agents, used at two concentrations, were activated carbon, bentonite, polyvinylpolypyrrolidone (PVPP), gelatin, egg albumin, isinglass-fish glue, and casein. Pesticides were selected with a wide range of properties (octanol-water partition coefficient (log K ow ) 2.7-6.3 and water solubility 0.0002-142) and belong to 11 chemical groups. Solid phase extraction (SPE) followed by gas chromatography (GC) with electron capture detector (ECD) were performed to analyze pesticide residues of the clarified fortified wine. The correlation of the clarifying agents' effectiveness to pesticide's chemical structure and properties (log K ow , water solubility) was investigated. The antagonistic and/or synergistic effects, occurring among the pesticides in the mixtures, were calculated by indices. Pesticide removal effectiveness results of the red wine were compared to those obtained from a white wine under the same experimental conditions and discussed. The order of decreasing adsorbent effectiveness (mixture of 23 pesticides) was: activated carbon 40% > gelatin 23% > egg albumin 21% > PVPP 18% > casein 12% > bentonite 7%. Isinglass showed 12% removal at the highest permitted concentration. In the case of 9 pesticides mixture, the effectiveness was quite higher but the order remained the same compared to 23 pesticides mixture. The removal of each pesticide from its single solution was generally the highest (particularly for hydrophobic pesticides). Adsorption on fining agents is increased by increasing hydrophobicity and decreasing hydrophilicity of organic pesticide molecules.

The role of potassium, magnesium and calcium in the Enhanced Biological Phosphorus Removal treatment plants.

PubMed

Barat, R; Montoya, T; Seco, A; Ferrer, J

2005-09-01

Cations as potassium and magnesium play an important role in maintaining the stability of Enhanced Biological Phosphorus Removal (EBPR) process. In this paper potassium, magnesium and calcium behaviour in EBPR treatment plants has been studied. An ASM2d model extension which takes into account the role of potassium and magnesium in the EBPR process has been developed. Finally, a simulation of the effect on P removal of a shortage of K and Mg was studied. The experimental results showed that K and Mg play an important role in the EBPR process being cotransported with P into and out of bacterial cells. It has been observed that calcium is not involved in P release and uptake. The values of the molar ratios K/P (0.28 mol K mol P(-1)) and Mg/P (0.36 mol Mg mol P(-1)) were obtained accomplishing the charge balance, with different K/Mg mass ratios and without phosphorus precipitation. Model predictions accurately reproduced experimental data. The simulations carried out showed the important effect of the K and Mg influent concentration for P removal efficiency. The results illustrate that the proposed ASM2d model extension must be considered in order to accurately simulate the phosphorus removal process.

Complex interactions of multiple aquatic consumers: an experimental mesocosm manipulation

USGS Publications Warehouse

Richardson, William B.; Threlkeld, Stephen T.

1993-01-01

In 7-m3 outdoor tanks filled with lake water, the presence/absence of omnivorous young-of-the- year Micropterus salmoides), zooplanktivorous Menidia beryllina , and herbivorous larval Hyla chrysocelis was experimentally manipulated. A cross-classified design was used to assess the interactive effects of these vertebrate consumers on the experimental food webs. The primary effects of the experimental manipulations on food web components were two- and three-way interactions in which the effect of a given treatment was dependent on the presence of another treatment. Results suggest that the addition or removal of consumers may not cause linear, additive changes in food webs.

[Treatment of Urban Runoff Pollutants by a Multilayer Biofiltration System].

PubMed

Wang, Xiao-lu; Zuo, Jian-e; Gan, Li-li; Xing, Wei; Miao, Heng-feng; Ruan, Wen-quan

2015-07-01

In order to control the non-point source pollution from road runoff in Wuxi City effectively, a multilayer biofiltration system was designed to remove a variety of pollutants according to the characteristics of road runoff in Wuxi, and the experimental research was carried out to study the effect on rainwater pollution purification. The results show that the system has a good performance on removing suspended solids (SS), organic pollutant (COD), nitrogen and phosphorus: all types of multilayer biofiltration systems have a high removal rate for SS, which can reach 90%. The system with activated carbon (GAC) has higher removal rates for COD and phosphorus. The system with zeolite (ZFM) has a relatively better removal efficiency for nitrogen. The addition of wood chips in the system can significantly improve the system efficiency for nitrogen removal. Between the two configurations of layered and distributed wood chips, configurations of distributed wood chips reach higher COD, phosphorus and nitrogen pollutants removal efficiencies since they can reduce the release of wood chips dissolution.

Barriers and opportunities for passive removal of indoor ozone

NASA Astrophysics Data System (ADS)

Gall, Elliott T.; Corsi, Richard L.; Siegel, Jeffrey A.

2011-06-01

This paper presents a Monte Carlo simulation to assess passive removal materials (PRMs) that remove ozone with no additional energy input and minimal byproduct formation. Distributions for air exchange rate in a subset of homes in Houston, Texas, were taken from the literature and combined with background ozone removal rates in typical houses and previous experimentally determined ozone deposition velocities to activated carbon cloth and gypsum wallboard PRMs. The median ratio of indoor to outdoor ozone was predicted to be 0.16 for homes with no PRMs installed and ranged from 0.047 to 0.12 for homes with PRMs. Median values of ozone removal effectiveness in these homes ranged from 22% to 68% for the conditions investigated. Achieving an ozone removal effectiveness above 50% in half of the homes would require installing a large area of PRMs and providing enhanced air speed to transport pollutants to PRM surfaces. Challenges associated with achieving this removal include optimizing indoor transport and aesthetic implications of large surface areas of PRM materials.

Kinetic modeling of kraft delignification of Eucalyptus globulus

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

Santos, A.; Rodriguez, F.; Gilarranz, M.A.

1997-10-01

A kinetic model for the kraft pulping delignification of Eucalyptus globulus is proposed. This model is discriminated among some kinetic expressions often used in the literature, and the kinetic parameters are determined by fitting of experimental results. A total of 25 isothermal experiments at liquor-to-wood ratios of 50 and 5 L/kg have been carried out. Initial, bulk, and residual delignification stages have been observed during the lignin removal, the transitions being, referring to the lignin initial content, about 82 and 3%. Carbohydrate removal and effective alkali-metal and hydrosulfide consumption have been related with the lignin removal by means of effectivemore » stoichiometric coefficients for each stage, coefficients also being calculated by fitting of the experimental data. The kinetic model chosen has been used to simulate typical kraft pulping experiments carried out at nonisothermal conditions, using a temperature ramp. The model yields simulated values close to those obtained experimentally for the wood studied and also ably reproduces the trends of the literature data.« less

Theoretical and experimental analysis of the impacts of removable storage media and antivirus software on viral spread

NASA Astrophysics Data System (ADS)

Gan, Chenquan; Yang, Xiaofan

2015-05-01

In this paper, a new computer virus propagation model, which incorporates the effects of removable storage media and antivirus software, is proposed and analyzed. The global stability of the unique equilibrium of the model is independent of system parameters. Numerical simulations not only verify this result, but also illustrate the influences of removable storage media and antivirus software on viral spread. On this basis, some applicable measures for suppressing virus prevalence are suggested.

Quantifying fear effects on prey demography in nature.

PubMed

Peers, Michael J L; Majchrzak, Yasmine N; Neilson, Eric; Lamb, Clayton T; Hämäläinen, Anni; Haines, Jessica A; Garland, Laura; Doran-Myers, Darcy; Broadley, Kate; Boonstra, Rudy; Boutin, Stan

2018-06-13

In recent years, it has been argued that the effect of predator fear exacts a greater demographic toll on prey populations than the direct killing of prey. However, efforts to quantify the effects of fear have primarily relied on experiments that replace predators with predator cues. Interpretation of these experiments must consider two important caveats: (1) the magnitude of experimenter-induced predator cues may not be realistically comparable to those of the prey's natural sensory environment, and (2) given functional predators are removed from the treatments, the fear effect is measured in the absence of any consumptive effects, a situation which never occurs in nature. We contend that demographic consequences of fear in natural populations may have been overestimated because the intensity of predator cues applied by experimenters in the majority of studies has been unnaturally high, in some instances rarely occurring in nature without consumption. Furthermore, the removal of consumption from the treatments creates the potential situation that individual prey in poor condition (those most likely to contribute strongly to the observed fear effects via starvation or reduced reproductive output) may have been consumed by predators in nature prior to the expression of fear effects, thus confounding consumptive and fear effects. Here, we describe an alternative treatment design that does not utilize predator cues, and in so doing, better quantifies the demographic effect of fear on wild populations. This treatment substitutes the traditional cue experiment where consumptive effects are eliminated and fear is simulated with a design where fear is removed and consumptive effects are simulated through the experimental removal of prey. Comparison to a natural population would give a more robust estimate of the effect of fear in the presence of consumption on the demographic variable of interest. This approach represents a critical advance in quantifying the mechanistic pathways through which predation structures ecological communities. Discussing the merits of both treatments will motivate researchers to go beyond simply describing the existence of fear effects and focus on testing their true magnitude in wild populations and natural communities. © 2018 by the Ecological Society of America.

Combined electrocoagulation and electroflotation for removal of fluoride from drinking water.

PubMed

Zuo, Qianhai; Chen, Xueming; Li, Wei; Chen, Guohua

2008-11-30

A combined electrocoagulation (EC) and electroflotation (EF) process was proposed to remove fluoride from drinking water. Its efficacy was investigated under different conditions. Experimental results showed that the combined process could remove fluoride effectively. The total hydraulic retention time required was only 30 min. After treatment, the fluoride concentration was reduced from initial 4.0-6.0mg/L to lower than 1.0mg/L. The influent pH value was found to be a very important variable that affected fluoride removal significantly. The optimal influent pH range is 6.0-7.0 at which not only can effective defluoridation be achieved, but also no pH readjustment is needed after treatment. In addition, it was found that SO(4)(2-) had negative effect; Ca(2+) had positive effect; while Cl(-) had little effect on the fluoride removal. The EC charge loading, EF charge loading and energy consumption were 3.0 Faradays/m(3), 1.5 Faradays/m(3), and 1.2 kWh/m(3), respectively, under typical conditions where fluoride was reduced from initial 4.0 to 0.87 mg/L.

Overview of air biofiltration - basic technology, economics and integration with other control technologies for effective treatment of air toxics

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

Govind, R.; Bishop, D.F.

1996-12-31

This paper provides an overview of air biofiltration with experimental data on the performance of peat/compost, pelletized packed bed and structured media biofilters. It is shown that use of high surface area per unit volume structured media results in higher contaminant treatment rates per unit biofilter volume. Peat/compost biofilters exhibit lower removal efficiencies at high (> 100 ppmv) inlet contaminant concentrations and require control of media moisture content. Increase of temperature results in increasing biodegradation rates. It is shown that use of structured ceramic media allows effective control of biomass buildup by continuous removal of biomass from the biofilter mediamore » and that the biomass removal rate depends on nutrient flowrate. An experimental system is presented which enables biofilm kinetics to be determined and a simple biofilter model is developed in this paper. A group contribution approach has been developed to estimate biokinetic parameter which allows biofiltration effectiveness to be determined for a variety of volatile organic compounds (VOCs). Finally, a procedure is presented, illustrated by an example, which is used to develop an integrated process for effective treatment of air contaminants. 22 refs., 12 figs., 4 tabs.« less

Application of multiwalled carbon nanotubes and its magnetite derivative for emulsified oil removal from produced water.

PubMed

Ibrahim, Taleb H; Sabri, Muhammad A; Khamis, Mustafa I

2018-05-10

Multiwalled carbon nanotubes and their magnetite derivatives were employed as adsorbents for emulsified oil removal from produced water. The experimental parameters for maximum emulsified oil removal efficiency and effective regeneration of these adsorbents were determined. The optimum parameters in terms of adsorbent dosage, contact time, salinity, pH and temperature were 3.0 g/L, 20.0 min, 0 ppm, 7.0 and 25°C for both adsorbents. Due to their low density, multiwalledcarbon nanotubes could not be successfully employed in packed bed columns. The magnetite derivative has a larger density and hence, for the removal of emulsified oil from produced water packed bed column studies were performed utilizing multiwalled carbon magnetite nanotubes. The packed bed column efficiency and behaviour were evaluated using Thomas, Clark, Yan et al. and Bohart and Adams models. The Yan model was found to best describe the column experimental data. The adsorbents were regenerated using n-hexane and reused several times for oil removal from produced water without any significant decrease in their initial adsorption capacities.

Malachite Green Adsorption by Spent Coffee Grounds

NASA Astrophysics Data System (ADS)

Syamimie Atirah Mat, Siti; Zati Hanani Syed Zuber, Sharifah; Rahim, Siti Kartini Enche Ab; Sohaimi, Khairunissa Syairah Ahmad; Halim, Noor Amirah Abdul; Fauziah Zainudin, Nor; Aida Yusoff, Nor; Munirah Rohaizad, Nor; Hidayah Ishak, Noor; Anuar, Adilah; Sarip, Mohd Sharizan Md

2018-03-01

In this work, the ability of spent coffee grounds (SCG) as a low-cost adsorbent to remove malachite green (MG) from aqueous solutions was studied. Batch adsorption tests were carried out to observe the effect of various experimental parameters such as contact time, initial concentration of malachite green and adsorbent dosage on the removal of dye. The results obtained show that the percentage of dye removal will decreased with the increased of initial concentration of dye in the range of 50 mg/L to 250 mg/L. Besides, percentage removal of dye was also found to be increased as the contact time increased until it reached equilibrium condition. The results also showed that the adsorbent dosage in range of 0.2 g to 1.0 g is proportional to the percentage removal of malachite green dye. Study on the kinetic adsorption and isotherm adsorption has also been investigated. The adsorption isotherm data were described by Langmuir isotherm with high-correlation coefficients while the experimental data showed the pseudo-second-order kinetics model was the best model for the adsorption of MG by SCG with the coefficients of correlation R2 > 0.9978.

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

NASA Astrophysics Data System (ADS)

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

2012-02-01

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

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

PubMed

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

2012-02-01

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

Benzotriazole removal on post-Cu CMP cleaning

NASA Astrophysics Data System (ADS)

Jiying, Tang; Yuling, Liu; Ming, Sun; Shiyan, Fan; Yan, Li

2015-06-01

This work investigates systematically the effect of FA/O II chelating agent and FA/O I surfactant in alkaline cleaning solutions on benzotriazole (BTA) removal during post-Cu CMP cleaning in GLSI under the condition of static etching. The best detergent formulation for BTA removal can be determined by optimization of the experiments of single factor and compound cleaning solution, which has been further confirmed experimentally by contact angle (CA) measurements. The resulting solution with the best formulation has been measured for the actual production line, and the results demonstrate that the obtained cleaning solution can effectively and efficiently remove BTA, CuO and abrasive SiO2 without basically causing interfacial corrosion. This work demonstrates the possibility of developing a simple, low-cost and environmentally-friendly cleaning solution to effectively solve the issues of BTA removal on post-Cu CMP cleaning in a multi-layered copper wafer. Project supported by the Major National Science and Technology Special Projects (No. 2009ZX02308).

Improved Processes to Remove Naphthenic Acids

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

Aihua Zhang; Qisheng Ma; Kangshi Wang

2005-12-09

In the past three years, we followed the work plan as we suggested in the proposal and made every efforts to fulfill the project objectives. Based on our large amount of creative and productive work, including both of experimental and theoretic aspects, we received important technical breakthrough on naphthenic acid removal process and obtained deep insight on catalytic decarboxylation chemistry. In detail, we established an integrated methodology to serve for all of the experimental and theoretical work. Our experimental investigation results in discovery of four type effective catalysts to the reaction of decarboxylation of model carboxylic acid compounds. The adsorptionmore » experiment revealed the effectiveness of several solid materials to naphthenic acid adsorption and acidity reduction of crude oil, which can be either natural minerals or synthesized materials. The test with crude oil also received promising results, which can be potentially developed into a practical process for oil industry. The theoretical work predicted several possible catalytic decarboxylation mechanisms that would govern the decarboxylation pathways depending on the type of catalysts being used. The calculation for reaction activation energy was in good agreement with our experimental measurements.« less

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.

Retention and wear behaviors of two implant overdenture stud-type attachments at different implant angulations.

PubMed

Choi, Jae-Won; Bae, Ji-Hyeon; Jeong, Chang-Mo; Huh, Jung-Bo

2017-05-01

Implant angulation should be considered when selecting an attachment. Some in vitro studies have investigated the relationship between implant angulation and changes in the retention force of the stud attachment, but few studies have evaluated the effect of cyclic loading and repeated cycles of insertion and removal on the stud attachment. The purpose of this in vitro study was to evaluate the effects of implant angulation on the retentive characteristics of overdentures with 2 different stud attachments, an experimental system and O-rings in red and orange, after cyclic loading and repeated insertion and removal cycles. The canine region of a mandibular experimental model was fitted with 2 implant fixtures with 2 different stud attachment systems at implant angulations of 0, 15, or 30 degrees. A mastication simulator was used to simulate cyclic loading, and a universal testing machine was used to evaluate retentive force changes after repeated insertion and removal cycles. To simulate the numbers of mastication and insertion and removal cycles per annum, 400000 cyclic loadings and 1080 insertion and removal cycles were performed. Wear patterns and attachment surface deformations were evaluated by scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction (α=.05/3=.017), and the paired-sample Student t test (α=.05). When retentive forces before and after testing were compared, O-ring showed significant retention loss at all implant angulations (P<.001). In contrast, the experimental system showed little retention loss in the 0- and 15-degree models (P>.05), whereas the 30-degree model showed a significant increase in retentive force (P=.001). At all implant angulations, retention loss increased significantly for the orange O-ring, followed by the red O-ring, and the experimental system (P<.001). Scanning electron microscopy analysis showed more intense wear in the matrix than the patrix (abutment that matches to matrix) and more severe wear and deformation of the O-ring rubber matrix than of the experimental zirconia ball. Upon completion of the experiment, wear and deformation were found for all attachment systems. Even when implants are not installed in parallel, the experimental system can be used without involving great loss of retention. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

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

PubMed

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

2013-09-12

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

Removal of NO and SO2 in Corona Discharge Plasma Reactor with Water Film

NASA Astrophysics Data System (ADS)

He, Yuanji; Dong, Liming; Yang, Jiaxiang

2004-04-01

In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water, and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NOx removal under suitable conditions is obtained in our experiments.

The Design and Implementation of Adsorptive Removal of Cu(II) from Leachate Using ANFIS

PubMed Central

Turan, Nurdan Gamze; Ozgonenel, Okan

2013-01-01

Clinoptilolite was investigated for the removal of Cu(II) ions from industrial leachate. Adaptive neural fuzzy interface system (ANFIS) was used for modeling the batch experimental system and predicting the optimal input values, that is, initial pH, adsorbent dosage, and contact time. Experiments were studied under laboratory batch and fixed bed conditions. The outcomes of suggested ANFIS modeling were then compared to a full factorial experimental design (23), which was utilized to assess the effect of three factors on the adsorption of Cu(II) ions in aqueous leachate of industrial waste. It was observed that the optimized parameters are almost close to each other. The highest removal efficiency was found as about 93.65% at pH 6, adsorbent dosage 11.4 g/L, and contact time 33 min for batch conditions of 23 experimental design and about 90.43% at pH 5, adsorbent dosage 15 g/L and contact time 35 min for batch conditions of ANFIS. The results show that clinoptilolite is an efficient sorbent and ANFIS, which is easy to implement and is able to model the batch experimental system. PMID:23844405

Application of Taguchi L16 design method for comparative study of ability of 3A zeolite in removal of Rhodamine B and Malachite green from environmental water samples.

PubMed

Rahmani, Mashaallah; Kaykhaii, Massoud; Sasani, Mojtaba

2018-01-05

This study aimed to investigate the efficiency of 3A zeolite as a novel adsorbent for removal of Rhodamine B and Malachite green dyes from water samples. To increase the removal efficiency, effecting parameters on adsorption process were investigated and optimized by adopting Taguchi design of experiments approach. The percentage contribution of each parameter on the removal of Rhodamine B and Malachite green dyes determined using ANOVA and showed that the most effective parameters in removal of RhB and MG by 3A zeolite are initial concentration of dye and pH, respectively. Under optimized condition, the amount predicted by Taguchi design method and the value obtained experimentally, showed good closeness (more than 94.86%). Good adsorption efficiency obtained for proposed methods indicates that, the 3A zeolite is capable to remove the significant amounts of Rhodamine B and Malachite green from environmental water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of Taguchi L16 design method for comparative study of ability of 3A zeolite in removal of Rhodamine B and Malachite green from environmental water samples

NASA Astrophysics Data System (ADS)

Rahmani, Mashaallah; Kaykhaii, Massoud; Sasani, Mojtaba

2018-01-01

This study aimed to investigate the efficiency of 3A zeolite as a novel adsorbent for removal of Rhodamine B and Malachite green dyes from water samples. To increase the removal efficiency, effecting parameters on adsorption process were investigated and optimized by adopting Taguchi design of experiments approach. The percentage contribution of each parameter on the removal of Rhodamine B and Malachite green dyes determined using ANOVA and showed that the most effective parameters in removal of RhB and MG by 3A zeolite are initial concentration of dye and pH, respectively. Under optimized condition, the amount predicted by Taguchi design method and the value obtained experimentally, showed good closeness (more than 94.86%). Good adsorption efficiency obtained for proposed methods indicates that, the 3A zeolite is capable to remove the significant amounts of Rhodamine B and Malachite green from environmental water samples.

Comparison of coagulation, ozone and ferrate treatment processes for color, COD and toxicity removal from complex textile wastewater.

PubMed

Malik, Sameena N; Ghosh, Prakash C; Vaidya, Atul N; Waindeskar, Vishal; Das, Sera; Mudliar, Sandeep N

2017-09-01

In this study, the comparative performance of coagulation, ozone, coagulation + ozone + coagulation and potassium ferrate processes to remove chemical oxygen demand (COD), color, and toxicity from a highly polluted textile wastewater were evaluated. Experimental results showed that ferrate alone had no effect on COD, color and toxicity removal. Whereas, in combination with FeSO 4 , it has shown the highest removal efficiency of 96.5%, 83% and 75% for respective parameters at the optimal dose of 40 mgL -1 + 3 ml FeSO 4 (1 M) in comparison with other processes. A seed germination test using seeds of Spinach (Spinacia oleracea) also indicated that ferrate was more effective in removing toxicity from contaminated textile wastewater. Potassium ferrate also produces less sludge with maximum contaminant removal, thereby making the process more economically feasible. Fourier transform infrared spectroscopy (FTIR) analysis also shows the cleavage of the chromophore group and degradation of textile wastewater during chemical and oxidation treatment processes.

Design and experimental study on desulphurization process of ship exhaust

NASA Astrophysics Data System (ADS)

Han, Mingyang; Hao, Shan; Zhou, Junbo; Gao, Liping

2018-02-01

This desulfurization process involves removing sulfur oxides with seawater or alkaline aqueous solutions and then treating the effluent by aeration and pH adjustment before discharging it into the ocean. In the desulfurization system, the spray tower is the key equipment and the venturi tubes are the pretreatment device. The two stages of plates are designed to fully absorb sulfur oxides in exhaust gases. The spiral nozzles atomize and evenly spray the desulfurizers into the tower. This study experimentally investigated the effectiveness of this desulfurization process and the factors influencing it under laboratory conditions, with a diesel engine exhaust used to represent ship exhaust. The experimental results show that this process can effectively absorb the SO2 in the exhaust. When the exhaust flow rate was 25 m3/h and the desulfurizer flow rate was 4 L/min, the sulfur removal efficiency (SRE) reached 99.7%. The flow rate, alkalinity, and temperature of seawater were found to have significant effects on the SRE. Adjusting seawater flow rate (SWR) and alkalinity within certain ranges can substantially improve the SRE.

Improvement of magnetorheological finishing surface quality by nanoparticle jet polishing

NASA Astrophysics Data System (ADS)

Peng, Wenqiang; Li, Shengyi; Guan, Chaoliang; Shen, Xinmin; Dai, Yifan; Wang, Zhuo

2013-04-01

Nanoparticle jet polishing (NJP) is presented as a posttreatment to remove magnetorheological finishing (MRF) marks. In the NJP process the material is removed by chemical impact reaction, and the material removal rate of convex part is larger than that of the concave part. Smoothing thus can progress automatically in the NJP process. In the experiment, a silica glass sample polished by MRF was polished by NJP. Experiment results showed the MRF marks were removed clearly. The uniform polishing process shows that the NJP process can remove the MRF marks without destroying the original surface figure. The surface root-mean-square roughness is improved from 0.72 to 0.41 nm. power spectral density analysis indicates the surface quality is improved, and the experimental result validates effective removal of MRF marks by NJP.

Purification effects of five landscape plants on river landscape water

NASA Astrophysics Data System (ADS)

Ling, Sun; Lei, Zheng; Mao, Qinqing; Ji, Qingxin

2017-12-01

Five species of landscape plants which are scindapsus aureus, water hyacinth, cockscomb, calendula officinalis and salvia splendens were used as experimental materials to study their removal effects on nitrogen, phosphorus, chemical oxygen demand (CODMn) and suspended solids (SS) in urban river water. The results show that the 5 landscape plants have good adaptability and vitality in water body, among them, water hyacinth had the best life signs than the other 4 plants, and its plant height and root length increased significantly. They have certain removal effects on the nitrogen, phosphorus, CODMn (Chemical Oxygen Demand) and SS (Suspended Substance) in the landscape water of Dalong Lake, Xuzhou. Scindapsus aureus, water hyacinth, cockscomb, calendula officinalis and salvia splendens on the removal rate of total nitrogen were 76.69%, 78.57%, 71.42%, 69.64%, 67.86%; the ammonia nitrogen removal rate were 71.06%, 74.28%, 67.85%, 63.02%, 59.81%;the total phosphorus removal rate were 78.70%, 81.48%, 73.15%, 72.22%, 68.52%;the orthophosphate removal rates were 78.37%, 80.77%, 75.96%, 75.96%, 71.15%;the removal rate of CODMn was 52.5%, 55.35%, 46.02%, 45.42%, 44.19%; the removal rate of SS was 81.4%, 86%, 79.1%, 76.7%, 74.42%.The purification effect of 5 kinds of landscape plants of Dalong Lake in Xuzhou City: water hyacinth> scindapsus aureus>cockscomb>calendula officinalis>salvia splendens.

EEG Artifact Removal Using a Wavelet Neural Network

NASA Technical Reports Server (NTRS)

Nguyen, Hoang-Anh T.; Musson, John; Li, Jiang; McKenzie, Frederick; Zhang, Guangfan; Xu, Roger; Richey, Carl; Schnell, Tom

2011-01-01

!n this paper we developed a wavelet neural network. (WNN) algorithm for Electroencephalogram (EEG) artifact removal without electrooculographic (EOG) recordings. The algorithm combines the universal approximation characteristics of neural network and the time/frequency property of wavelet. We. compared the WNN algorithm with .the ICA technique ,and a wavelet thresholding method, which was realized by using the Stein's unbiased risk estimate (SURE) with an adaptive gradient-based optimal threshold. Experimental results on a driving test data set show that WNN can remove EEG artifacts effectively without diminishing useful EEG information even for very noisy data.

The Effect of Golden Pothos in Reducing the Level of Volatile Organic Compounds in a Simulated Spacecraft Cabin

NASA Technical Reports Server (NTRS)

Ursprung, Matthew; Amiri, Azita; Kayatin, Matthew; Perry, Jay

2016-01-01

The impact of Golden Pothos on indoor air quality was studied against a simulated spacecraft trace contaminant load model, consistent with the International Space Station (ISS), containing volatile organic compounds (VOCs) and formaldehyde. Previous research provides inconclusive results on the efficacy of plant VOC removal which this projects seeks to rectify through a better experimental design. This work develops a passive system for removing common VOC's from spacecraft and household indoor air and decreasing the necessity for active cabin trace contaminant removal systems.

Application of integrated ozone and granular activated carbon for decolorization and chemical oxygen demand reduction of vinasse from alcohol distilleries.

PubMed

Hadavifar, Mojtaba; Younesi, Habibollah; Zinatizadeh, Ali Akbar; Mahdad, Faezeh; Li, Qin; Ghasemi, Zahra

2016-04-01

This study investigates the treatment of the distilleries vinasse using a hybrid process integrating ozone oxidation and granular activated carbons (GAC) in both batch and continuous operation mode. The batch-process studies have been carried out to optimize initial influent pH, GAC doses, the effect of the ozone (O3) and hydrogen peroxide (H2O2) concentrations on chemical oxygen demand (COD) and color removal of the distilleries vinasse. The continuous process was carried out on GAC and ozone treatment alone as well as the hybrid process comb both methods to investigate the synergism effectiveness of the two methods for distilleries vinasse COD reduction and color removal. In a continuous process, the Yan model described the experimental data better than the Thomas model. The efficiency of ozonation of the distilleries vinasse was more effective for color removal (74.4%) than COD removal (25%). O3/H2O2 process was not considerably more effective on COD and color removal. Moreover, O3/GAC process affected negatively on the removal efficiency by reducing COD and color from distilleries vinasse. The negative effect decreased by increasing pH value of the influent. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of some operational parameters on the arsenic removal by electrocoagulation using iron electrodes

PubMed Central

2014-01-01

Arsenic contamination of drinking water is a global problem that will likely become more apparent in future years as scientists and engineers measure the true extent of the problem. Arsenic poisoning is preventable though as there are several methods for easily removing even trace amounts of arsenic from drinking water. In the present study, electrocoagulation was evaluated as a treatment technology for arsenic removal from aqueous solutions. The effects of parameters such as initial pH, current density, initial concentration, supporting electrolyte type and stirring speed on removal efficiency were investigated. It has been observed that initial pH was highly effective on the arsenic removal efficiency. The highest removal efficiency was observed at initial pH = 4. The obtained experimental results showed that the efficiency of arsenic removal increased with increasing current density and decreased with increasing arsenic concentration in the solution. Supporting electrolyte had not significant effects on removal, adding supporting electrolyte decreased energy consumption. The effect of stirring speed on removal efficiency was investigated and the best removal efficiency was at the 150 rpm. Under the optimum conditions of initial pH 4, current density of 0.54 mA/cm2, stirring speed of 150 rpm, electrolysis time of 30 minutes, removal was obtained as 99.50%. Energy consumption in the above conditions was calculated as 0.33 kWh/m3. Electrocoagulation with iron electrodes was able to bring down 50 mg/L arsenic concentration to less than 10 μg/L at the end of electrolysis time of 45 minutes with low electrical energy consumption as 0.52 kWh/m3. PMID:24991426

Comparison of nickel oxide and palladium nanoparticle loaded on activated carbon for efficient removal of methylene blue: kinetic and isotherm studies of removal process.

PubMed

Arabzadeh, S; Ghaedi, M; Ansari, A; Taghizadeh, F; Rajabi, M

2015-02-01

Palladium nanoparticles (Pd-NPs) and nickel oxide nanoparticles (NiO-NPs) were synthesized and loaded on activated carbon (AC). This novel material successfully used for the removal of methylene blue (MB) dye from aqueous medium. Full characterization of both material using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and Brunauer-Emmet-Teller analyses for Pd-NP show their high surface area (>1340 m(2)/g) and low pore size (<20 Å) and average particle size lower than 45 Å and for NiO-NP show their high surface area (>1316.1554 m(2)/g) and low pore size (<20 Å) and average particle size lower than 46 Å in addition to high reactive atom and presence of various functional groups. These unique properties make them possible for efficient removal of MB. In batch experimental set-up, optimum conditions for maximum removal of MB by both adsorbents were attained following searching effect of variables such as central composite design. The Langmuir isotherm was found to be highly recommended for fitting the experimental equilibrium data. The kinetic of adsorption of MB on both adsorbents strongly can be fitted by a combination of pseudo-second order and intraparticle diffusion pathway. The experimental result achieved in this article shows the superiority of Pd-NP-AC for MB removal than NiO-NP-AC, so the maximum adsorption capacities of Pd-NP-AC and NiO-NP-AC were 555.5 mg/g and 588.2 mg/g, respectively. © The Author(s) 2015.

Wet scrubbing of biomass producer gas tars using vegetable oil

NASA Astrophysics Data System (ADS)

Bhoi, Prakashbhai Ramabhai

The overall aims of this research study were to generate novel design data and to develop an equilibrium stage-based thermodynamic model of a vegetable oil based wet scrubbing system for the removal of model tar compounds (benzene, toluene and ethylbenzene) found in biomass producer gas. The specific objectives were to design, fabricate and evaluate a vegetable oil based wet scrubbing system and to optimize the design and operating variables; i.e., packed bed height, vegetable oil type, solvent temperature, and solvent flow rate. The experimental wet packed bed scrubbing system includes a liquid distributor specifically designed to distribute a high viscous vegetable oil uniformly and a mixing section, which was designed to generate a desired concentration of tar compounds in a simulated air stream. A method and calibration protocol of gas chromatography/mass spectroscopy was developed to quantify tar compounds. Experimental data were analyzed statistically using analysis of variance (ANOVA) procedure. Statistical analysis showed that both soybean and canola oils are potential solvents, providing comparable removal efficiency of tar compounds. The experimental height equivalent to a theoretical plate (HETP) was determined as 0.11 m for vegetable oil based scrubbing system. Packed bed height and solvent temperature had highly significant effect (p0.05) effect on the removal of model tar compounds. The packing specific constants, Ch and CP,0, for the Billet and Schultes pressure drop correlation were determined as 2.52 and 2.93, respectively. The equilibrium stage based thermodynamic model predicted the removal efficiency of model tar compounds in the range of 1-6%, 1-4% and 1-2% of experimental data for benzene, toluene and ethylbenzene, respectively, for the solvent temperature of 30° C. The NRTL-PR property model and UNIFAC for estimating binary interaction parameters are recommended for modeling absorption of tar compounds in vegetable oils. Bench scale experimental data from the wet scrubbing system would be useful in the design and operation of a pilot scale vegetable oil based system. The process model, validated using experimental data, would be a key design tool for the design and optimization of a pilot scale vegetable oil based system.

Effect of storage conditions on the calorific value of municipal solid waste.

PubMed

Nzioka, Antony Mutua; Hwang, Hyeon-Uk; Kim, Myung-Gyun; Yan, Cao Zheng; Lee, Chang-Soo; Kim, Young-Ju

2017-08-01

Storage conditions are considered to be an important factor as far as waste material characteristics are concerned. This experimental investigation was conducted using municipal solid waste (MSW) with a high moisture content and varying composition of organic waste. The objective of this study was to understand the effect of storage conditions and temperature on the moisture content and calorific value of the waste. Samples were subjected to two different storage conditions and investigated at specified temperatures. The composition of sample materials investigated was varied for each storage condition and temperature respectively. Gross calorific value was determined experimentally while net calorific value was calculated using empirical formulas proposed by other researchers. Results showed minimal changes in moisture content as well as in gross and net calorific values when the samples were subjected to sealed storage conditions. Moisture content reduced due to the ventilation process and the rate of moisture removal increased with a rise in storage temperature. As expected, rate of moisture removal had a positive effect on gross and net calorific values. Net calorific values also increased at varying rates with a simultaneous decrease in moisture content. Experimental investigation showed the effectiveness of ventilation in improving the combustion characteristics of the waste.

Pilot-scale investigation on the removal of organic foulants in secondary effluent by slow sand filtration prior to ultrafiltration.

PubMed

Zheng, Xing; Ernst, Mathias; Jekel, Martin

2010-05-01

Natural biofiltration processes have been verified as effective pre-treatment choice improving the performance of low-pressure membranes (MF/UF) in wastewater reclamation. In the present work, pilot-scale slow sand filtration (SSF) was used to simulate bank filtration at high filtration rates (from 0.25m/h to 0.5m/h) to filter secondary effluent prior to UF. The results showed that SSF improved the performance of UF to a large extent. Related to previous work biopolymers are considered as major dissolved organic foulants in treated wastewater. The removal of these organic foulants in slow sand filters and factors affecting the performance of SSF were investigated. It was observed that the removal of biopolymers took place mainly at the upper sand layer and was related to biological degradation. Tests on the degradability of biopolymers verified that they are biodegradable. Sixteen months monitoring of biopolymer concentration in the secondary effluent indicated that it varied seasonally. In winter season the concentration was much higher than during the summer months. Higher temperature and lower biopolymer concentration led to more effective foulants removal and more sustainable operation of SSF. During the whole experimental period, the performance of SSF was always better at filtration rate of 0.25m/h than at 0.5m/h. Under the present experimental conditions, SSF exhibited stable and effective biopolymer removal at temperatures higher than 15 degrees C, at biopolymer concentrations lower than 0.5mg C/L and with sufficient oxygen available.

Optimization of Acid Black 172 decolorization by electrocoagulation using response surface methodology

PubMed Central

2012-01-01

This paper utilizes a statistical approach, the response surface optimization methodology, to determine the optimum conditions for the Acid Black 172 dye removal efficiency from aqueous solution by electrocoagulation. The experimental parameters investigated were initial pH: 4–10; initial dye concentration: 0–600 mg/L; applied current: 0.5-3.5 A and reaction time: 3–15 min. These parameters were changed at five levels according to the central composite design to evaluate their effects on decolorization through analysis of variance. High R2 value of 94.48% shows a high correlation between the experimental and predicted values and expresses that the second-order regression model is acceptable for Acid Black 172 dye removal efficiency. It was also found that some interactions and squares influenced the electrocoagulation performance as well as the selected parameters. Optimum dye removal efficiency of 90.4% was observed experimentally at initial pH of 7, initial dye concentration of 300 mg/L, applied current of 2 A and reaction time of 9.16 min, which is close to model predicted (90%) result. PMID:23369574

Experimental study of acoustic agglomeration and fragmentation on coal-fired ash

NASA Astrophysics Data System (ADS)

Shen, Guoqing; Huang, Xiaoyu; He, Chunlong; Zhang, Shiping; An, Liansuo; Wang, Liang; Chen, Yanqiao; Li, Yongsheng

2018-02-01

As the major part of air pollution, inhalable particles, especially fine particles are doing great harm to human body due to smaller particle size and absorption of hazardous components. However, the removal efficiency of current particles filtering devices is low. Acoustic agglomeration is considered as a very effective pretreatment technique for removing particles. Fine particles collide, agglomerate and grow up in the sound field and the fine particles can be removed by conventional particles devices easily. In this paper, the agglomeration and fragmentation of 3 different kinds of particles with different size distributions are studied experimentally in the sound field. It is found that there exists an optimal frequency at 1200 Hz for different particles. The agglomeration efficiency of inhalable particles increases with SPL increasing for the unimodal particles with particle diameter less than 10 μm. For the bimodal particles, the optimal SPLs are 115 and 120 dB with the agglomeration efficiencies of 25% and 55%. A considerable effectiveness of agglomeration could only be obtained in a narrow SPL range and it decreases significantly over the range for the particles fragmentation.

Using Chitosan/CHPATC as coagulant to remove color and turbidity of industrial wastewater: Optimization through RSM design.

PubMed

Momeni, Meysam Mohammad; Kahforoushan, Davood; Abbasi, Farhang; Ghanbarian, Saeid

2018-04-01

One of the most important solid-liquid separation processes is coagulation and flocculation that is extensively used in the primary treatment of industrial wastewater. The biopolymers, because of biodegradable properties and low cost have been used as coagulants. In this study, chitosan as a natural coagulant of choice, was modified by (3-chloro 2-hydroxypropyl)trimethylammonium chloride and was used to remove the color and turbidity of industrial wastewater. To evaluate the effect of pH, settling time, the initial turbidity of wastewater, the amount of coagulant, and the concentration of dye (Melanoidin) were chosen to study their effects on removal of wastewater color and turbidity. The experiments were done in a batch system by using a jar test. To achieve the optimum conditions for the removal of color and turbidity, the response surface methodology (RSM) experimental design method was used. The results obtained from experiments showed that the optimum conditions for the removal of color were as: pH = 3, concentration of dye = 1000 mg/L, settling time = 78.93 min, and dose of coagulant = 3 g/L. The maximum color removal in these conditions was predicted 82.78% by the RSM model. The optimal conditions for the removal of turbidity of the waste water were as: pH = 5.66, initial turbidity = 60 NTU, settling time = 105 min, and amount of coagulant = 3 g/L. The maximum turbidity removal in these circumstances was predicted 94.19% by the model. The experimental results obtained in optimum conditions for removal of color and turbidity were 76.20% and 90.14%, respectively, indicating the high accuracy of the prediction model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biofiltration of isopentane in peat and compost packed beds

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

Wang, Z.; Govind, R.

1997-05-01

Commercially available biofiltration systems have used natural bioactive materials in packed beds due to low media cost and easy availability. Detailed understanding and modeling of biofiltration systems are lacking in existing literature. Experimental studies on the isopentane treatment in air using peat- and compost-packed beds were conducted with inlet isopentane concentrations of 360 to 960 ppmv, and empty-bed gas-phase residence times of 2 to 10 min. High removal efficiencies (>90%) were achieved at low contaminant concentrations (<500 ppmv) and large empty-bed gas-phase residence times (>8 min). For both peat and compost biofilters, there was an optimal water content that gavemore » the highest removal efficiency. For higher water content, mass transfer of isopentane through the liquid phase controlled the biofiltration removal efficiency. At low water content, irreversible changes in the bioactivity of peat and compost occurred, resulting in an irrecoverable loss of removal efficiency. Increases in biofilter bed temperature from 25 to 40 C improved the removal efficiency. A mathematical model incorporating the effect of water content and temperature was developed to describe the packed-bed biofilter performance. Model predictions agreed closely with experimental data.« less

Correlation between expression of CatSper family and sperm profiles in the adult mouse testis following Iranian Kerack abuse.

PubMed

Amini, M; Shirinbayan, P; Behnam, B; Roghani, M; Farhoudian, A; Joghataei, M T; Koruji, M

2014-05-01

Illicit drug use can be an important cause of male infertility. The aim of this study was to investigate the effects of an Iranian illicit drug, Kerack, on sperm parameters, testicular structure and CatSper genes expression of mice. In this study, 25 male mice were divided into five groups consisting of control, sham and three experimental groups. All animal in experimental groups were addicted to Kerack for 7 days. These experimental groups include experimental I which was given Kerack at a dose of 5 mg/kg, experimental II, 35 mg/kg and experimental III, 70 mg/kg, intraperitoneally twice a day for a period of 35 days. Mice were then sacrificed and spermatozoas were removed from cauda epididymis and analyzed for count, motility, morphology (normal/abnormal) and viability. Right testes were removed, weighed and processed for light microscopic studies whereas left testes removed were subjected to total mRNA extraction for using in real-time PCR (RT-PCR). The results were analyzed by performing anova (Tukey's tests) and Pearson correlation coefficient. Sperm parameters and seminiferous epithelium thickness were decreased in experimental groups (dose-dependently) vs. sham and control groups (p < 0.05). RT-PCR results showed that CatSper 2, 3, 4 genes expressions were reduced with 35 and 70 mg/kg injected Kerack when compared with control testes (p ≤ 0.05). However, CatSper1 expression was only reduced with high dose injected Kerack (70 mg/kg) in comparison to control testes (p ≤ 0.05). This study shows the deleterious effects of Kerack used in Iran on testis structure and sperm parameters in general, and particularly sperm morphology in adult mouse. It could down-regulate the expression of CatSper genes, resulting in depression of sperm motility. © 2014 American Society of Andrology and European Academy of Andrology.

Monoatomic layer removal mechanism in chemical mechanical polishing process: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Si, Lina; Guo, Dan; Luo, Jianbin; Lu, Xinchun

2010-03-01

Molecular dynamics simulations of nanoscratching processes were used to study the atomic-scale removal mechanism of single crystalline silicon in chemical mechanical polishing (CMP) process and particular attention was paid to the effect of scratching depth. The simulation results under a scratching depth of 1 nm showed that a thick layer of silicon material was removed by chip formation and an amorphous layer was formed on the silicon surface after nanoscratching. By contrast, the simulation results with a depth of 0.1 nm indicated that just one monoatomic layer of workpiece was removed and a well ordered crystalline surface was obtained, which is quite consistent with previous CMP experimental results. Therefore, monoatomic layer removal mechanism was presented, by which it is considered that during CMP process the material was removed by one monoatomic layer after another, and the mechanism could provide a reasonable understanding on how the high precision surface was obtained. Also, the effects of the silica particle size and scratching velocity on the removal mechanism were investigated; the wear regimes and interatomic forces between silica particle and workpiece were studied to account for the different removal mechanisms with indentation depths of 0.1 and 1 nm.

78 FR 57171 - Experimental Removal of Barred Owls To Benefit Threatened Northern Spotted Owls; Record of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-17

... action alternatives vary by the number and location of study areas, the type of experimental design... nonlethal), and the type of experimental design (demography vs. occupancy). All action alternatives are...-FF01E00000] Experimental Removal of Barred Owls To Benefit Threatened Northern Spotted Owls; Record of...

Specific removal of autoantibodies by extracorporeal immunoadsorption ameliorates experimental autoimmune myasthenia gravis.

PubMed

Lazaridis, Konstantinos; Dalianoudis, Ioannis; Baltatzidi, Vasiliki; Tzartos, Socrates J

2017-11-15

Myasthenia gravis (MG) is caused by autoantibodies, the majority of which target the muscle acetylcholine receptor (AChR). Plasmapheresis and IgG-immunoadsorption are useful therapy options, but are highly non-specific. Antigen-specific immunoadsorption would remove only the pathogenic autoantibodies, reducing the possibility of side effects while maximizing the benefit. We have extensively characterized such adsorbents, but in vivo studies are missing. We used rats with experimental autoimmune MG to perform antigen-specific immunoadsorptions over three weeks, regularly monitoring symptoms and autoantibody titers. Immunoadsorption was effective, resulting in a marked autoantibody titer decrease while the immunoadsorbed, but not the mock-treated, animals showed a dramatic symptom improvement. Overall, the procedure was found to be efficient, suggesting the subsequent initiation of clinical trials. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of effectiveness of cement removal from implant-retained crowns using a proposed circular crisscross flossing technique.

PubMed

Ferreira, Cimara Fortes; Shafter, Mohamed Amer; Jain, Vinay; Wicks, Russel Anthony; Linder, Erno; Ledo, Carlos Alberto da Silva

2018-02-13

Extruded cement during dental implant crown cementation may cause peri-implant diseases if not removed adequately. Evaluate the efficiency of removal of cement after cementation of implant crowns using an experimental "circular crisscross flossing technique (CCCFT) flossing technique, compared to the conventional "C" shape flossing technique (CSFT). Twenty-four patients rendered 29 experimental and 29 control crowns. Prefabricated abutments were secured to the implant with the margins at least 1 mm subgingivally. The abutments were scanned using CADCAM technology and Emax crowns were fabricated in duplicates. Each crown was cemented separately and excess cement was removed using the CSFT and the CCFT techniques. After completion of cementation was completed, the screw access holes were accessed and the crown was unscrewed along with the abutment. The samples were disinfected using 70% ethanol for 10 minutes. Crowns were divided into 4 parts using a marker in order to facilitate measurement data collection. Vertical and horizontal measurements were made for extruded cement for each control and experimental groups by means of a digital microscope. One-hundred and seventeen measurements were made for each group. Mann-Whitney test was applied to verify statistical significance between the groups. The CCFT showed a highly statistically significant result (104.8 ± 13.66, p<0.0001) for cement removal compared with the CSFT (291.8 ± 21.96, p<0.0001). The vertical lengths of the extruded cement showed a median of 231.1 µm (IQR = 112.79 -398.39) and 43.62 µm (IQR = 0 - 180.21) for the control and the experimental flossing techniques, respectively. The horizontal length of the extruded cement showed a median of 987.1 µm (IQR = 476.7 - 1,933.58) and 139.2 µm (IQR = 0 - 858.28) for the control and the experimental flossing techniques, respectively. The CCFT showed highly statistically significant less cement after implant crowns cementation when compared with the CSFT.

Adsorption of mixtures of nutrients and heavy metals in simulated urban stormwater by different filter materials.

PubMed

Reddy, Krishna R; Xie, Tao; Dastgheibi, Sara

2014-01-01

In recent years, several best management practices have been developed for the removal of different types of pollutants from stormwater runoff that lead to effective stormwater management. Filter materials that remove a wide range of contaminants have great potential for extensive use in filtration systems. In this study, four filter materials (calcite, zeolite, sand, and iron filings) were investigated for their adsorption and efficiency in the removal of nutrients and heavy metals when they exist individually versus when they co-exist. Laboratory batch experiments were conducted separately under individual and mixed contaminants conditions at different initial concentrations. Adsorption capacities varied under the individual and mixed contaminant conditions due to different removal mechanisms. Most filter materials showed lower removal efficiency under mixed contaminant conditions. In general, iron filings were found effective in the removal of nutrients and heavy metals simultaneously to the maximum levels. Freundlich and Langmuir isotherms were used to model the batch adsorption results and the former better fitted the experimental results. Overall, the results indicate that the filter materials used in this study have the potential to be effective media for the treatment of nutrients and heavy metals commonly found in urban stormwater runoff.

Anemonefish depletion reduces survival, growth, reproduction and fishery productivity of mutualistic anemone-anemonefish colonies

NASA Astrophysics Data System (ADS)

Frisch, Ashley J.; Rizzari, Justin R.; Munkres, Katherine P.; Hobbs, Jean-Paul A.

2016-06-01

Intimate knowledge of both partners in a mutualism is necessary to understand the ecology and evolution of each partner, and to manage human impacts that asymmetrically affect one of the partners. Although anemonefishes and their host anemones are iconic mutualists and widely sought by ornamental fisheries, the degree to which anemones depend on anemonefishes, and thus the colony-level effects of collecting anemonefishes, is not well understood. We tracked the size and abundance of anemone Entacmaea quadricolor and anemonefish Amphiprion melanopus colonies for 3 yr after none, some, or all of the resident anemonefish were experimentally removed. Total and partial removal of anemonefish had rapid and sustained negative effects on growth, reproduction and survival of anemones, as well as cascading effects on recruitment and productivity of anemonefish in the remaining colony. As predicted, total removal of anemonefish caused acute declines in size and abundance of anemones, although most anemone colonies (76 %) slowly resumed growth and reproduction after the arrival of anemonefish recruits, which subsequently grew and defended the hosts. Partial removal of anemonefish had similar but typically less severe effects on anemones. Remarkably, the colony-level effects on anemones and anemonefish were proportional to the size and number of anemonefish that were experimentally removed. In particular, anemone survival and anemonefish productivity were highest when one or more adult anemonefish remained in the colony, suggesting that adult fish not only enhanced the protection of anemones, but also increased the recruitment and/or survival of conspecifics. We conclude that the relationship between E. quadricolor and A. melanopus is not only obligate, but also demographically rigid and easily perturbed by anemonefish fisheries. Clearly, these two species must be managed together as a unit and with utmost precaution. To this end, we propose several tangible management actions that will help to minimize fishing effects.

Effects of Leaf Removal and Applied Water on Flavonoid Accumulation in Grapevine (Vitis vinifera L. cv. Merlot) Berry in a Hot Climate.

PubMed

Yu, Runze; Cook, Michael G; Yacco, Ralph S; Watrelot, Aude A; Gambetta, Gregory; Kennedy, James A; Kurtural, S Kaan

2016-11-02

The relationships between variations in grapevine (Vitis vinifera L. cv. Merlot) fruit zone light exposure and water deficits and the resulting berry flavonoid composition were investigated in a hot climate. The experimental design involved application of mechanical leaf removal (control, pre-bloom, post-fruit set) and differing water deficits (sustained deficit irrigation and regulated deficit irrigation). Flavonol and anthocyanin concentrations were measured by C18 reversed-phased HPLC and increased with pre-bloom leaf removal in 2013, but with post-fruit set leaf removal in 2014. Proanthocyanidin isolates were characterized by acid catalysis in the presence of excess phloroglucinol followed by reversed-phase HPLC. Post-fruit set leaf removal increased total proanthocyanidin concentration in both years, whereas no effect was observed with applied water amounts. Mean degree of polymerization of skin proanthocyanidins increased with post-fruit set leaf removal compared to pre-bloom, whereas water deficit had no effect. Conversion yield was greater with post-fruit set leaf removal. Seed proanthocyanidin concentration was rarely affected by applied treatments. The application of post-fruit set leaf removal, regardless of water deficit. increased the proportion of proanthocyanidins derived from the skin, whereas no leaf removal or pre-bloom leaf removal regardless of water deficit increased the proportion of seed-derived proanthocyanidins. The study provides fundamental information to viticulturists and winemakers on how to manage red wine grape low molecular weight phenolics and polymeric proanthocyanidin composition in a hot climate.

Treatment of high salinity organic wastewater by membrane electrolysis

NASA Astrophysics Data System (ADS)

Dongfang, Shen; Jinghuan, Ma; Ying, Liu; Chenguang, Zhao

2018-03-01

The effects of different operating conditions on the treatment of electrolytic wastewater were investigated by analyzing the removal rate of ammonia and COD before and after wastewater treatment by cation exchange membrane. Experiment shows that as the running time increases the electrolysis effect first increases after the smooth. The removal rate of ammonia will increase with the increase of current density, and the removal rate of COD will increase first and then decrease with the increase of current density. The increase of the temperature of the electrolytic solution will slowly increase the COD removal rate to saturation, but does not affect the removal of ammonia nitrogen. When the flow rate is less than 60L / h, the change of influent flow rate will not affect the removal of ammonia nitrogen, but the effect on COD is small, which will increase and decrease slightly. After the experiment, the surface of the cation exchange membrane was analyzed by cold field scanning electron microscopy and X-ray energy dispersive spectrometer. The surface contamination and the pollutant were determined. The experimental results showed that the aggregates were mainly chlorinated Sodium, calcium and magnesium inorganic salts, which will change the morphology of the film to reduce porosity, reduce the mass transfer efficiency, affecting the electrolysis effect.

EVALUATION OF INTERNALLY STAGED COAL BURNERS AND SORBENT JET AERODYNAMICS FOR COMBINED SO2/NOX CONTROL IN UTILITY BOILERS; VOLUME 2. TESTING IN A 100 MILLION BTU/HR EXPERIMENTAL FURNACE

EPA Science Inventory

The report givesresults of100 million Btu/hr (29 MWt) experimental furnace to explore methods for achieving effective S02 removal in a coalfired utility boiler using calcium-based sorbents, through appropriate selection of injection location and injector design/operating paramete...

Experimental study of the thermal stability of materials in high temperature oxygen-containing media

NASA Technical Reports Server (NTRS)

Abaltusov, Y. Y.; Bagramyan, A. R.; Grishin, A. M.; Yukhvid, V. I.

1986-01-01

An experimental study is made of the interaction of several materials with a high temperature medium containing oxygen. The temperature of the surface was measured as a function of time. It is found that the higher the velocity of mass removal from the surface, the more effective is the material from the viewpoint of heat resistance.

Synthesis and characterization of Cadmium selenide nanoparticles loaded on activated carbon and its efficient application for removal of Muroxide from aqueous solution

NASA Astrophysics Data System (ADS)

Ghaedi, M.; Amirabad, S. Zamani; Marahel, F.; Nasiri Kokhdan, S.; Sahraei, R.; Nosrati, M.; Daneshfar, A.

2011-12-01

In the first, Cadmium selenide Nanoparticle loaded on activated carbon (CdSe-NP-AC) has been synthesized and characterized by different techniques including XRD and SEM. Then, this new adsorbent successfully has been applied for the removal of muroxide (MO) from aqueous solution in batch studies, while the effect of various experimental parameters like initial pH (pH 0), contact time, amount of (CdSe-NP-AC) and initial MO concentration ( C0) on its removal percentage was examined by one at a time optimization method. It was found following optimization of variable, the adsorption of MO onto (CdSe-NP-AC) followed pseudo-second-order kinetics and show Tempkin and Langmuir models for interpretation of experimental data. It was observed that by increasing the temperature the removal percentage was improved and the positive change in entropy (Δ S°) and heat of adsorption (Δ H°) show the endothermic nature of process, while the high negative value in Gibbs free energy change (Δ G°) indicates the feasible nature of adsorption process.

[Effects of different resin removal methods on shear bond strength of rebonded orthodontic brackets].

PubMed

Wu, Hai-miao; Zhao, Bin-jiao; Chen, Dong

2015-06-01

To compare the shear bond strength (SBS) of rebonded orthodontic metal brackets with different resin removal methods. Forty extracted premolars were chosen as samples and divided into 4 experimental groups. The teeth were bonded with brackets. The brackets from 3 groups were debonded while adhesive remnants were removed from bracket bases by methods of grinding, sandblasting, and direct flaming, respectively and then rebonded. The SBS values of all rebonded brackets were determined after pH cycling experiment for 30 days. Some rebonded bracket bases were selected and observed under scanning electron microscope (SEM). The data was analyzed by one-way ANOVA test using SPSS 13.0 software package. Statistical analysis revealed a significant difference of SBS values among the 4 experimental groups (P<0.05). The SBS values of the group by direct flaming was significantly lower compared to the other groups (P<0.05). There was no significant difference of SBS values among the other groups. The rebonded brackets after resin removal by grinding and sandblasting have a similar SBS compared to the initial brackets adhesive.

Study on Control of NH4 +-N in Surface Water by Photocatalytic

NASA Astrophysics Data System (ADS)

Zuo, Xiaoran; He, Honghua; Yang, Yue; Yan, Chao; Zhou, Ying

2018-01-01

NH4 +-N has become the main pollution factor affecting the surface water quality in China. Based on the theory of photolysis, the feasibility of photolysis removing NH4 +-N in surface water is studied. The effects of pH, CaO2 content and photolysis time on removal rate of NH4 +-N are studied. The actual study is based on Laboratory studies results. Experimental results show: When the pH<7, photolysis can increase the NH4 +-N content. And when pH>8, the photolysis can greatly reduce the NH4 +-N content in water. CaO2 can greatly remove NH4 +-N. The removal rate of NH4 +-N increased with the increase of photocatalytic time. When irradiated with UV light for 108 hours or the sun is irradiated for about 40 days, NH4 +-N content can be reduced from 4mg/L to 0.5mg/L under the optimum experimental conditions. Adjusting the pH of surface water is the most important condition for controlling NH4 +-N content.

Boron removal from aqueous solution by direct contact membrane distillation.

PubMed

Hou, Deyin; Wang, Jun; Sun, Xiangcheng; Luan, Zhaokun; Zhao, Changwei; Ren, Xiaojing

2010-05-15

The removal of boron from aqueous solution by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) hollow fiber membranes in the present work. The effect of pH, boron concentration, temperature and salt concentration of the feed solution on the boron rejection was investigated. The experimental results indicated that boron rejection was less dependent on the feed pH and salt concentration. DCMD process had high boron removal efficiency (>99.8%) and the permeate boron was below the maximum permissible level even at feed concentration as high as 750 mg/L. Although the permeate flux was enhanced exponentially with the feed temperature increasing, the influence of feed temperature on the boron rejection could be neglected. Finally, the natural groundwater sample containing 12.7 mg/L of boron was treated by DCMD process. The permeate boron kept below 20 microg/L whether the feed was acidified or not, but pre-acidification was helpful to maintain the permeate flux stability. All the experimental results indicated that DCMD could be efficiently used for boron removal from aqueous solution. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Effect of ferrate on green algae removal.

PubMed

Kubiňáková, Emília; Híveš, Ján; Gál, Miroslav; Fašková, Andrea

2017-09-01

Green algae Cladophora aegagropila, present in cooling water of thermal power plants, causes many problems and complications, especially during summer. However, algae and its metabolites are rarely eliminated by common removal methods. In this work, the elimination efficiency of electrochemically prepared potassium ferrate(VI) on algae from cooling water was investigated. The influence of experimental parameters, such as Fe(VI) dosage, application time, pH of the system, temperature and hydrodynamics of the solution on removal efficiency, was optimized. This study demonstrates that algae C. aegagropila can be effectively removed from cooling water by ferrate. Application of ferrate(VI) at the optimized dosage and under the suitable conditions (temperature, pH) leads to 100% removal of green algae Cladophora from the system. Environmentally friendly reduction products (Fe(III)) and coagulation properties favour the application of ferrate for the treatment of water contaminated with studied microorganisms compared to other methods such as chlorination and use of permanganate, where harmful products are produced.

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation.

PubMed

Olmez, T; Kabdaşli, I; Tünay, O

2007-01-01

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.

77 FR 14036 - Draft Environmental Impact Statement for Experimental Removal of Barred Owls to Benefit...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-08

... and location of study areas, the type of experimental design, duration of study, and method of barred... by the number and location of study areas, the type of experimental design, duration of the study...-FF01E00000] Draft Environmental Impact Statement for Experimental Removal of Barred Owls to Benefit...

Plaque removal efficacy of a battery-operated toothbrush compared to a manual toothbrush.

PubMed

Ruhlman, C D; Bartizek, R D; Biesbrock, A R

2001-08-01

Recently, a new power toothbrush has been marketed with a design that fundamentally differs from other marketed power toothbrushes, in that it incorporates a round oscillating head, in conjunction with fixed bristles. The objective of this study was to compare the plaque removal efficacy of a control manual toothbrush (Colgate Navigator) to this experimental power toothbrush (Crest SpinBrush) following a single use. This study was a randomized, controlled, examiner-blind, 4-period crossover design which examined plaque removal with the two toothbrushes following a single use in 40 completed subjects. Plaque was scored before and after brushing using the Turesky Modification of the Quigley-Hein Index. Baseline plaque scores were 1.77 for both the experimental toothbrush and control toothbrush treatment groups. With respect to all surfaces examined, the experimental toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.48 while the control toothbrush delivered an adjusted mean difference of 0.35. The experimental toothbrush removed, on average, 37.6% more plaque than the control toothbrush. These results were statistically significant (P< 0.001). With respect to buccal surfaces, the experimental toothbrush delivered an adjusted mean difference between baseline and post-brushing plaque scores of 0.54 while the control toothbrush delivered an adjusted mean difference of 0.42. This represents 27.8% more plaque removal with the experimental toothbrush compared to the control toothbrush. These results were also statistically significant (P= 0.001). Results on lingual surfaces also demonstrated statistically significantly (P< 0.001) greater plaque removal for the experimental toothbrush with an average of 53.4% more plaque removal.

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.

Laser removal of graffiti from Pink Morelia Quarry

NASA Astrophysics Data System (ADS)

Penide, J.; Quintero, F.; Riveiro, A.; Sánchez-Castillo, A.; Comesaña, R.; del Val, J.; Lusquiños, F.; Pou, J.

2013-11-01

Morelia is an important city sited in Mexico. Its historical center reflects most of their culture and history, especially of the colonial period; in fact, it was appointed World Heritage Site by UNESCO. Sadly, there is a serious problem with graffiti in Morelia and its historical center is the worst affected since its delicate charming is definitely damaged. Hitherto, the conventional methods employed to remove graffiti from Pink Morelia Quarry (the most used building stone in Morelia) are quite aggressive to the appearance of the monuments, so actually, they are not a very good solution. In this work, we performed a study on the removal of graffiti from Pink Morelia Quarry by high power diode laser. We carried out an extensive experimental study looking for the optimal processing parameters, and compared a single-pass with a multi-pass method. Indeed, we achieved an effective cleaning without producing serious side effects in the stone. In conclusion, the multi-pass method emitting in continuous wave was revealed as the more effective operating modes to remove the graffiti.

Chemical activation of gasification carbon residue for phosphate removal

NASA Astrophysics Data System (ADS)

Kilpimaa, Sari; Runtti, Hanna; Lassi, Ulla; Kuokkanen, Toivo

2012-05-01

Recycling of waste materials provides an economical and environmentally significant method to reduce the amount of waste. Bioash formed in the gasification process possesses a notable amount of unburned carbon and therefore it can be called a carbon residue. After chemical activation carbon residue could be use to replace activated carbon for example in wastewater purification processes. The effect of chemical activation process variables such as chemical agents and contact time in the chemical activation process were investigated. This study also explored the effectiveness of the chemically activated carbon residue for the removal of phosphate from an aqueous solution. The experimental adsorption study was performed in a batch reactor and the influence of adsorption time, initial phosphate concentration and pH was studied. Due to the carbon residue's low cost and high adsorption capacity, this type of waste has the potential to be utilised for the cost-effective removal of phosphate from wastewaters. Potential adsorbents could be prepared from these carbonaceous by-products and used as an adsorbent for phosphate removal.

Fe-FeS2 adsorbent prepared with iron powder and pyrite by facile ball milling and its application for arsenic removal.

PubMed

Min, Xiaobo; Li, Yangwenjun; Ke, Yong; Shi, Meiqing; Chai, Liyuan; Xue, Ke

2017-07-01

Arsenic is one of the major pollutants and a worldwide concern because of its toxicity and chronic effects on human health. An adsorbent of Fe-FeS 2 mixture for effective arsenic removal was successfully prepared by mechanical ball milling. The products before and after arsenic adsorption were characterized with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent shows high arsenic removal efficiency when molar ratio of iron to pyrite is 5:5. The experimental data of As(III) adsorption are fitted well with the Langmuir isotherm model with a maximal adsorption capacity of 101.123 mg/g. And As(V) data were described perfectly by the Freundlich model with a maximal adsorption capacity of 58.341 L/mg. As(III) is partial oxidized to As(V) during the adsorption process. High arsenic uptake capability and cost-effectiveness of waste make it potentially attractive for arsenic removal.

Experimental exploration of the hydrodynamic effect polishing machinability for different types of material

NASA Astrophysics Data System (ADS)

Peng, W. Q.; Li, Y.; Wang, Z.; Li, S. Y.

2018-01-01

Hydrodynamic effect polishing (HEP), in which the material removal relies on the chemisorption between nanoparticles and the workpiece surface in elastic mode, can realize automatic level smooth surface without surface/subsurface damage. The machinability of different types of optical material (such as monocrystalline silicon and crystalline quartz, amorphous silicate glass, Zerodur and so on) were investigated experimentally. The workpiece surfaces before and after being polished by HEP was observed by atomic force microscopy. The experimental results show the surface roughness of monocrystalline silicon and quartz, amorphous silicate glass have decreased from Rms 0.737nm to Rms 0.175nm, Rms 0.490nm to Rms 0.187nm, Rms 0.469nm to Rms 0.157nm respectively, and meanwhile all the defects and bumpy structures have been removed clearly. However the surface roughness has increased from Rms 0.213nm to Rms 0.321nm with the obvious increment of micro unevenness. By comparison, we can conclude that excellent performance is shown when HEP is applied on the optical material structure with a single monocrystalline or amorphous component. However the ultrasmooth surface cannot be obtained when HEP was applied on the combinational materials such as Zerodur glass. The micro unevenness increases gradually along with polishing process due to the different material removal of the monocrystalline and amorphous component.

Influence of denitrification reactor retention time distribution (RTD) on dissolved oxygen control and nitrogen removal efficiency.

PubMed

Raboni, Massimo; Gavasci, Renato; Viotti, Paolo

2015-01-01

Low concentrations of dissolved oxygen (DO) are usually found in biological anoxic pre-denitrification reactors, causing a reduction in nitrogen removal efficiency. Therefore, the reduction of DO in such reactors is fundamental for achieving good nutrient removal. The article shows the results of an experimental study carried out to evaluate the effect of the anoxic reactor hydrodynamic model on both residual DO concentration and nitrogen removal efficiency. In particular, two hydrodynamic models were considered: the single completely mixed reactor and a series of four reactors that resemble plug-flow behaviour. The latter prove to be more effective in oxygen consumption, allowing a lower residual DO concentration than the former. The series of reactors also achieves better specific denitrification rates and higher denitrification efficiency. Moreover, the denitrification food to microrganism (F:M) ratio (F:MDEN) demonstrates a relevant synergic action in both controlling residual DO and improving the denitrification performance.

Effect of enzyme secreting bacterial pretreatment on enhancement of aerobic digestion potential of waste activated sludge interceded through EDTA.

PubMed

Kavitha, S; Adish Kumar, S; Yogalakshmi, K N; Kaliappan, S; Rajesh Banu, J

2013-12-01

In this study, the effect of Ethylene diamine tetra acetic acid (EDTA) on Extracellular polymeric substance (EPS) removal tailed with bacterial enzymatic pretreatment on aerobic digestion of activated sludge was studied. In order to enhance the accessibility of sludge to the enzyme secreting bacteria; the extracellular polymeric substances were removed using EDTA. EDTA efficiently removed the EPS with limited cell lysis and enhanced the sludge enzyme activity at its lower concentration of 0.2 g/g SS. The sludge was then subjected to bacterial pretreatment to enhance the aerobic digestion. In aerobic digestion the best results in terms of Suspended solids (SS) reduction (48.5%) and COD (Chemical oxygen demand) solubilization (47.3%) was obtained in experimental reactor than in control. These results imply that aerobic digestion can be enhanced efficiently through bacterial pretreatment of EPS removed sludge. Copyright © 2013 Elsevier Ltd. All rights reserved.

Large-scale modular biofiltration system for effective odor removal in a composting facility.

PubMed

Lin, Yueh-Hsien; Chen, Yu-Pei; Ho, Kuo-Ling; Lee, Tsung-Yih; Tseng, Ching-Ping

2013-01-01

Several different foul odors such as nitrogen-containing groups, sulfur-containing groups, and short-chain fatty-acids commonly emitted from composting facilities. In this study, an experimental laboratory-scale bioreactor was scaled up to build a large-scale modular biofiltration system that can process 34 m(3)min(-1)waste gases. This modular reactor system was proven effective in eliminating odors, with a 97% removal efficiency for 96 ppm ammonia, a 98% removal efficiency for 220 ppm amines, and a 100% removal efficiency of other odorous substances. The results of operational parameters indicate that this modular biofiltration system offers long-term operational stability. Specifically, a low pressure drop (<45 mmH2O m(-1)) was observed, indicating that the packing carrier in bioreactor units does not require frequent replacement. Thus, this modular biofiltration system can be used in field applications to eliminate various odors with compact working volume.

Effect of ultrasound on electrochemical chloride extraction from mortar

NASA Astrophysics Data System (ADS)

Chen, Yiqun; Yao, Wu; Zuo, Junqing

2018-03-01

In this paper, the effect of auxiliary ultrasound on electrochemical chloride extraction (ECE) was studied. The chloride removal efficiency was investigated by examining the chloride content with ultrasound-assisted ECE and changing the introducing time of ultrasound. The experimental results showed that removal of chloride ions was noted to be more effective in ECE treatment assisted with ultrasound treatment (UT). In addition, the lower w/c ratio led to more distinct effect of ultrasonic cavitation on chloride removal. Electrochemical behaviors measured with different treatment revealed that UT treatment was effective on moderating the corrosion condition. Microstructural analyses revealed a significant alteration in composition and morphology of cementitious phases with UT treatment. Pull-out tests indicated that ultrasound had a certain negative impact on the bond strength. Although the effect of introducing ultrasound in the first 2 weeks or the last 2 weeks on the extraction efficiency was not obvious, intermittent ultrasound could not only ensure the chloride extraction efficiency, but also reduce the adverse effect of ultrasound on the bond strength.

Unusual positional effects on flower sex in an andromonoecious tree: Resource competition, architectural constraints, or inhibition by the apical flower?

PubMed

Granado-Yela, Carlos; Balaguer, Luis; Cayuela, Luis; Méndez, Marcos

2017-04-01

Two, nonmutually exclusive, mechanisms-competition for resources and architectural constraints-have been proposed to explain the proximal to distal decline in flower size, mass, and/or femaleness in indeterminate, elongate inflorescences. Whether these mechanisms also explain unusual positional effects such as distal to proximal declines of floral performance in determinate inflorescences, is understudied. We tested the relative influence of these mechanisms in the andromonoecious wild olive tree, where hermaphroditic flowers occur mainly on apical and the most proximal positions in determinate inflorescences. We experimentally increased the availability of resources for the inflorescences by removing half of the inflorescences per twig or reduced resource availability by removing leaves. We also removed the apical flower to test its inhibitory effect on subapical flowers. The apical flower had the highest probability of being hermaphroditic. Further down, however, the probability of finding a hermaphroditic flower decreased from the base to the tip of the inflorescences. An experimental increase of resources increased the probability of finding hermaphroditic flowers at each position, and vice versa. Removal of the apical flower increased the probability of producing hermaphroditic flowers in proximal positions but not in subapical positions. These results indicate an interaction between resource competition and architectural constraints in influencing the arrangement of the hermaphroditic and male flowers within the inflorescences of the wild olive tree. Subapical flowers did not seem to be hormonally suppressed by apical flowers. The study of these unusual positional effects is needed for a general understanding about the functional implications of inflorescence architecture. © 2017 Botanical Society of America.

Clay-starch combination for micropollutants removal from wastewater treatment plant effluent.

PubMed

Mohd Amin, M F; Heijman, S G J; Rietveld, L C

2016-01-01

In this study, a new, more effective and cost-effective treatment alternative is investigated for the removal of pharmaceuticals from wastewater treatment plant effluent (WWTP-eff). The potential of combining clay with biodegradable polymeric flocculants is further highlighted. Flocculation is viewed as the best method to get the optimum outcome from clay. In addition, flocculation with cationic starch increases the biodegradability and cost of the treatment. Clay is naturally abundantly available and relatively inexpensive compared to conventional adsorbents. Experimental studies were carried out with existing naturally occurring pharmaceutical concentrations found and measured in WWTP-eff with atrazine spiking for comparison between the demineralised water and WWTP-eff matrix. Around 70% of the total measured pharmaceutical compounds were removable by the clay-starch combination. The effect of clay with and without starch addition was also highlighted.

Escherichia coli Removal in Biochar-Modified Biofilters: Effects of Biofilm

PubMed Central

Afrooz, A. R. M. Nabiul; Boehm, Alexandria B.

2016-01-01

The presence of microbial contaminants in urban stormwater is a significant concern for public health; however, their removal by traditional stormwater biofilters has been reported as inconsistent and inadequate. Recent work has explored the use of biochar to improve performance of stormwater biofilters under simplified conditions that do not consider potential effects of biofilm development on filter media. The present study investigates the role of biofilm on microbial contaminant removal performance of stormwater biofilters. Pseudomonas aeruginosa biofilms were formed in laboratory-scale sand and biochar-modified sand packed columns, which were then challenged with Escherichia coli laden synthetic stormwater containing natural organic matter. Results suggests that the presence of biofilm influences the removal of E. coli. However, the nature of the influence depends on the specific surface area and the relative hydrophobicity of filter media. The distribution of attached bacteria within the columns indicates that removal by filter media varies along the length of the column: the inlet was the primary removal zone regardless of experimental conditions. Findings from this research inform the design of field-scale biofilters for better and consistent performance in removing microbial contaminants from urban stormwater. PMID:27907127

Improved dialytic removal of protein-bound uraemic toxins with use of albumin binding competitors: an in vitro human whole blood study

PubMed Central

Tao, Xia; Thijssen, Stephan; Kotanko, Peter; Ho, Chih-Hu; Henrie, Michael; Stroup, Eric; Handelman, Garry

2016-01-01

Protein-bound uraemic toxins (PBUTs) cause various deleterious effects in end-stage kidney disease patients, because their removal by conventional haemodialysis (HD) is severely limited by their low free fraction in plasma. Here we provide an experimental validation of the concept that the HD dialytic removal of PBUTs can be significantly increased by extracorporeal infusion of PBUT binding competitors. The binding properties of indoxyl sulfate (IS), indole-3-acetic acid (IAA) and hippuric acid (HIPA) and their binding competitors, ibuprofen (IBU), furosemide (FUR) and tryptophan (TRP) were studied in uraemic plasma. The effect of binding competitor infusion on fractional removal of PBUT was then quantified in an ex vivo single-pass HD model using uraemic human whole blood. The infusion of a combination of IBU and FUR increased the fractional removal of IS from 6.4 ± 0.1 to 18.3 ± 0.4%. IAA removal rose from 16.8 ± 0.3 to 34.5 ± 0.7%. TRP infusion increased the removal of IS and IAA to 10.5 ± 0.1% and 27.1 ± 0.3%, respectively. Moderate effects were observed on HIPA removal. Pre-dialyzer infusion of PBUT binding competitors into the blood stream can increase the HD removal of PBUTs. This approach can potentially be applied in current HD settings. PMID:27001248

Evaluation of palatal plate thickness of maxillary prosthesis on phonation- a comparative clinical study.

PubMed

Zakkula, Srujana; B, Sreedevi; Anne, Gopinadh; Manne, Prakash; Bindu O, Swetha Hima; Atla, Jyothi; Deepthi, Sneha; Chaitanya A, Krishna

2014-04-01

Prosthodontic treatment involves clinical procedures which influence speech performance directly or indirectly. Prosthetic rehabilitation of missing teeth with partial or complete maxillary removable dentures influences the individual voice characteristics like Phonation, resonance etc. To evaluate the effect of Acrylic palatal plate thickness (1mm-3mm) of maxillary prosthesis on phonation. Twelve subjects were selected randomly between the age group of 20-25 years who have full complement of teeth and have no speech problems. Speech evaluation was done under four experimental conditions i.e. Without any experimental acrylic palatal plate (control), with experimental acrylic palatal plates of thickness 1 mm, 2 mm and 3 mm respectively. The speech material for phonation test consisted of Vowels sounds /a/, /i/, and /o/. Speech analysis to assess phonation was done using digital acoustic analysis (PRAAT software). The obtained results were statistically analyzed by One-way ANOVA and Tukey's multiple post-hoc for comparison of four experimental conditions with respect to different vowel sounds. Mean harmonics to noise ratio (HNR) values obtained for all the Experimental conditions did not show significant difference (p>0.05). In conclusion, an increase in the thickness of the acrylic palatal plate of maxillary prosthesis for about 1 mm - 3mm in complete or partial maxillary removable dentures resulted in no significant effect on phonation of vowel sounds /a/, /i/ and /o/. Increasing the thickness of the palatal plate from 1 mm to 3 mm has not shown any significant effect on the phonation.

Comparison of hand hygiene procedures for removing Bacillus cereus spores.

PubMed

Sasahara, Teppei; Hayashi, Shunji; Hosoda, Kouichi; Morisawa, Yuji; Hirai, Yoshikazu

2014-01-01

Bacillus cereus is a spore-forming bacterium. B. cereus occasionally causes nosocomial infections, in which hand contamination with the spores plays an important role. Therefore, hand hygiene is the most important practice for controlling nosocomial B. cereus infections. This study aimed to determine the appropriate hand hygiene procedure for removing B. cereus spores. Thirty volunteers' hands were experimentally contaminated with B. cereus spores, after which they performed 6 different hand hygiene procedures. We compared the efficacy of the procedures in removing the spores from hands. The alcohol-based hand-rubbing procedures scarcely removed them. The soap washing procedures reduced the number of spores by more than 2 log10. Extending the washing time increased the spore-removing efficacy of the washing procedures. There was no significant difference in efficacy between the use of plain soap and antiseptic soap. Handwashing with soap is appropriate for removing B. cereus spores from hands. Alcohol-based hand-rubbing is not effective.

Applying multivariate analysis as decision tool for evaluating sediment-specific remediation strategies.

PubMed

Pedersen, Kristine B; Lejon, Tore; Jensen, Pernille E; Ottosen, Lisbeth M

2016-05-01

Multivariate methodology was employed for finding optimum remediation conditions for electrodialytic remediation of harbour sediment from an Arctic location in Norway. The parts of the experimental domain in which both sediment- and technology-specific remediation objectives were met were identified. Objectives targeted were removal of the sediment-specific pollutants Cu and Pb, while minimising the effect on the sediment matrix by limiting the removal of naturally occurring metals while maintaining low energy consumption. Two different cell designs for electrochemical remediation were tested and final concentrations of Cu and Pb were below background levels in large parts of the experimental domain when operating at low current densities (<0.12 mA/cm(2)). However, energy consumption, remediation times and the effect on naturally occurring metals were different for the 2- and 3-compartment cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative efficacy of two battery-powered toothbrushes on dental plaque removal.

PubMed

Ruhlman, C Douglas; Bartizek, Robert D; Biesbrock, Aaron R

2002-01-01

A number of clinical studies have consistently demonstrated that power toothbrushes deliver superior plaque removal compared to manual toothbrushes. Recently, a new power toothbrush (Crest SpinBrush) has been marketed with a design that fundamentally differs from other marketed power toothbrushes. Other power toothbrushes feature a small, round head designed to oscillate for enhanced cleaning between the teeth and below the gumline. The new power toothbrush incorporates a similar round oscillating head in conjunction with fixed bristles, which allows the user to brush with optimal manual brushing technique. The objective of this randomized, examiner-blind, parallel design study was to compare the plaque removal efficacy of a positive control power toothbrush (Colgate Actibrush) to an experimental toothbrush (Crest SpinBrush) following a single use among 59 subjects. Baseline plaque scores were 1.64 and 1.40 for the experimental toothbrush and control toothbrush treatment groups, respectively. With regard to all surfaces examined, the experimental toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.47, while the control toothbrush delivered an adjusted mean difference of 0.33. On average, the difference between toothbrushes was statistically significant (p = 0.013). Because the covariate slope for the experimental group was statistically significantly greater (p = 0.001) than the slope for the control group, a separate slope model was used. Further analysis demonstrated that the experimental group had statistically significantly greater plaque removal than the control group for baseline plaque scores above 1.43. With respect to buccal surfaces, using a separate slope analysis of covariance, the experimental toothbrush delivered an adjusted mean difference between baseline and post-brushing plaque scores of 0.61, while the control toothbrush delivered an adjusted mean difference of 0.39. This difference between toothbrushes was also statistically significant (p = 0.002). On average, the results on lingual surfaces demonstrated similar directional scores favoring the experimental toothbrush; however these results did not achieve statistical significance. In conclusion, the experimental Crest SpinBrush, with its novel fixed and oscillating bristle design, was found to be more effective than the positive control Colgate Actibrush, which is designed with a small round oscillating cluster of bristles.

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.

Investigation on removal of malachite green using EM based compost as adsorbent.

PubMed

Bhagavathi Pushpa, T; Vijayaraghavan, J; Sardhar Basha, S J; Sekaran, V; Vijayaraghavan, K; Jegan, J

2015-08-01

The discarded materials from different sources can be utilized as effective materials in wastewater remediation. This proposed study was aimed mainly to investigate the possibility of Effective Microorganisms based compost (EMKC), which is derived from the kitchen solid waste, as a non-conventional low cost adsorbent for the removal of malachite green from aqueous solution. Batch experiments were carried out to evaluate the optimum operating parameters like pH (2-9), initial dye concentration (50-1000mg/L), adsorbent particle size (0.6-2.36mm) and adsorbent dosage (2-12g/L). EMKC recorded maximum uptake of 136.6mg/g of MG at pH 8, initial dye concentration 1000mg/L, adsorbent particle size 1.18mm and adsorbent dosage 4g/L. Two and three parameter adsorption models were employed to describe experimental biosorption isotherm data. The results revealed that the Sips model resulted in better fit than other models. The pseudo-first and -second order models were applied to describe kinetic data, of which the pseudo-second order described experimental data better with high correlation coefficient. This investigation suggested that EMKC could be an effective and low cost material for the removal of malachite green dye from aqueous solution. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

Electrochemical removal of carbamazepine in water with Ti/PbO2 cylindrical mesh anode.

PubMed

García-Espinoza, J D; Gortáres-Moroyoqui, P; Orta-Ledesma, M T; Drogui, P; Mijaylova-Nacheva, P

2016-01-01

Carbamazepine (CBZ) is one of the most frequently detected organic compounds in the aquatic environment. Due to its bio-persistence and toxicity for humans and the environment its removal has become an important issue. The performance of the electrochemical oxidation process and in situ production of reactive oxygen species (ROS), such as O3 and H2O2, for CBZ removal have been studied using Ti/PbO2 cylindrical mesh anode in the presence of Na2SO4 as supporting electrolyte in a batch electrochemical reactor. In this integrated process, direct oxidation at anode and indirect oxidation by in situ electrogenerated ROS can occur simultaneously. The effect of several factors such as electrolysis time, current intensity, initial pH and oxygen flux was investigated by means of an experimental design methodology, using a 2(4) factorial matrix. CBZ removal of 83.93% was obtained and the most influential parameters turned out to be electrolysis time, current intensity and oxygen flux. Later, the optimal experimental values for CBZ degradation were obtained by means of a central composite design. The best operating conditions, analyzed by Design Expert(®) software, are the following: 110 min of electrolysis at 3.0 A, pH = 7.05 and 2.8 L O2/min. Under these optimal conditions, the model prediction (82.44%) fits very well with the experimental response (83.90 ± 0.8%). Furthermore, chemical oxygen demand decrease was quantified. Our results illustrated significant removal efficiency for the CBZ in optimized condition with second order kinetic reaction.

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.

Technological effect of vibroprocessing by flows of organic granular media

NASA Astrophysics Data System (ADS)

Lebedev, V. A.; Shishkina, A. P.; Davydova, I. V.; Morozova, A. V.

2018-03-01

The analysis of approaches to modeling of vibrational processing by granulated media is carried out. The vibroprocessing model which provides effective finishing of the surfaces of the parts due to the stone fruit organic media granules is developed. The model is based on the granule flow energy impact on the surface being treated. As the main characteristic of the organic media processing, a specific volumetric metal scrap is used, the physical meaning of which is the increase rate in the thickness of the material removed from the surface at a given velocity and pressure of the medium. It is shown that the metal scrap depends on the medium flow velocity, the height of the loading column of the granular medium, and the conditions for the formation of a medium stationary circulation motion. Based on the analysis of the results of experimental studies of the influence of amplitude-frequency characteristics on the removal of metal in the process of vibroprocessing with abrasive granules, the dependence of the specific volume metal removal is proposed for organic media processing, taking into account the threshold amplitude and frequency of oscillations of the working chamber, at which the effect of surface treatment is observed. The established set of relationships describing the effective conditions for vibroprocessing with stone organic media was obtained using experimental data, which allows us to assume that the model obtained is valid.

Statistical optimization of process parameters for the simultaneous adsorption of Cr(VI) and phenol onto Fe-treated tea waste biomass

NASA Astrophysics Data System (ADS)

Gupta, Ankur; Balomajumder, Chandrajit

2017-12-01

In this study, simultaneous removal of Cr(VI) and phenol from binary solution was carried out using Fe-treated tea waste biomass. The effect of process parameters such as adsorbent dose, pH, initial concentration of Cr(VI) (mg/L), and initial concentration of phenol (mg/L) was optimized. The analysis of variance of the quadratic model demonstrates that the experimental results are in good agreement with the predicted values. Based on experimental design at an initial concentration of 55 mg/L of Cr(VI), 27.50 mg/L of phenol, pH 2.0, 15 g/L adsorbent dose, 99.99% removal of Cr(VI), and phenol was achieved.

Drawbacks of Dialysis Procedures for Removal of EDTA

PubMed Central

Mónico, Andreia; Martínez-Senra, Eva; Cañada, F. Javier; Zorrilla, Silvia

2017-01-01

Ethylenediaminetetraacetic acid (EDTA) is a chelating agent commonly used in protein purification, both to eliminate contaminating divalent cations and to inhibit protease activity. For a number of subsequent applications EDTA needs to be exhaustively removed. Most purification methods rely in extensive dialysis and/or gel filtration in order to exchange or remove protein buffer components, including metal chelators. We report here that dialysis protocols, even as extensive as those typically employed for protein refolding, may not effectively remove EDTA, which is reduced only by approximately two-fold and it also persists after spin-column gel filtration, as determined by NMR and by colorimetric methods. Remarkably, the most efficient removal was achieved by ultrafiltration, after which EDTA became virtually undetectable. These results highlight a potentially widespread source of experimental variability affecting free divalent cation concentrations in protein applications. PMID:28099451

Comparing removal of trace organic compounds and assimilable organic carbon (AOC) at advanced and traditional water treatment plants.

PubMed

Lou, Jie-Chung; Lin, Chung-Yi; Han, Jia-Yun; Tseng, Wei-Biu; Hsu, Kai-Lin; Chang, Ting-Wei

2012-06-01

Stability of drinking water can be indicated by the assimilable organic carbon (AOC). This AOC value represents the regrowth capacity of microorganisms and has large impacts on the quality of drinking water in a distribution system. With respect to the effectiveness of traditional and advanced processing methods in removing trace organic compounds (including TOC, DOC, UV(254), and AOC) from water, experimental results indicate that the removal rate of AOC at the Cheng Ching Lake water treatment plant (which utilizes advanced water treatment processes, and is hereinafter referred to as CCLWTP) is 54%, while the removal rate of AOC at the Gong Yuan water treatment plant (which uses traditional water treatment processes, and is hereinafter referred to as GYWTP) is 36%. In advanced water treatment units, new coagulation-sedimentation processes, rapid filters, and biological activated carbon filters can effectively remove AOC, total organic carbon (TOC), and dissolved organic carbon (DOC). In traditional water treatment units, coagulation-sedimentation processes are most effective in removing AOC. Simulation results and calculations made using the AutoNet method indicate that TOC, TDS, NH(3)-N, and NO(3)-N should be regularly monitored in the CCLWTP, and that TOC, temperature, and NH(3)-N should be regularly monitored in the GYWTP.

Electrothermal debracketing: patient acceptance and effects on the dental pulp.

PubMed

Dovgan, J S; Walton, R E; Bishara, S E

1995-09-01

Adhesives bond ceramic brackets so effectively that their removal by mechanical forces can fracture the brackets and may damage the tooth surface. Electrothermal debracketers have been developed to facilitate removal; whether the heat generated will damage the underlying pulp is unclear. In our experiment, a prototype device with a high heat tip was used to remove brackets from premolars in patients. The following parameters were evaluated: (1) time required for removal, (2) patient acceptance, and (3) histologic effect on the pulp. Forty-eight experimental teeth planned for orthodontic extraction were bonded by a filled Bis-GMA composite resin and a monocrystalline sapphire bracket. After the chemically cured composite set, debracketing was performed according to the manufacturer's recommendations. Seventeen premolars were not etched or bracketed and served as controls. The interval between heat application and removal of the bracket was timed. Patients were questioned as to sensations during debracketing. Teeth were extracted at 5 to 7 or 28 to 32 days and histologically prepared. Pulps were evaluated for alterations. Brackets were removed in an average of 2.1 seconds, usually at the bracket/composite interface. Patient acceptance was generally positive. Pulpal necrosis was not observed but, in a number of specimens, slight inflammation and odontoblastic disruption occurred at both observation periods.

Removal of diclofenac and sulfamethoxazole from synthetic municipal waste water in microcosm downflow constructed wetlands: Start-up results.

PubMed

Nowrotek, Monika; Sochacki, Adam; Felis, Ewa; Miksch, Korneliusz

2016-01-01

The objectives of this study were to investigate the start-up removal of pharmaceutical compounds diclofenac and sulfamethoxazole in microcosm downflow constructed wetlands and their effect on the performance of the studied constructed wetlands, and also to assess the effect of plants on the removal of these compounds. The experimental system that was used in this 86-day experiment consisted of 24 columns filled up to 70 cm with predominantly sandy material. Four types of columns were used (six replicates) depending on the presence of plants (Phalaris arundinacea L. var. picta L.) and the presence of pharmaceutical compounds in the influent. The influent was synthetic municipal waste water to which a mixture of 5 mg/L of diclofenac and 5 mg/L of sulfamethoxazole was added. The observed removal of diclofenac was moderate (approx. 50%) and the removal of sulfamethoxazole was relatively low (24-30%). It was found that the removal of diclofenac and sulfamethoxazole was not affected by the vegetation. The presence of diclofenac and sulfamethoxazole in the influent had significant effect on the effluent concentration of N-NO3 and the water loss in the columns, which in both cases were lower than in the control columns. The scope for further research was discussed.

Polyamide nanofiltration membranes to remove aniline in aqueous solutions.

PubMed

Hidalgo, A M; León, G; Gómez, M; Murcia, M D; Bernal, M D; Ortega, S

2014-01-01

Aniline is commonly used in a number of industrial processes. It is known to be a harmful and persistent pollutant and its presence in wastewater requires treatment before disposal. In this paper, the effectiveness of nanofiltration (NF) to remove aniline from aqueous solutions is studied in a flat membrane test module using two thin-layer composite membranes of polyamide (NF97 and NF99HF). The influence of different operational variables (applied pressure, feed concentration and pH) on the removal of aniline from synthetic aqueous solutions was analysed. The experimental NF results are compared with results previously obtained by reverse osmosis. Based on this comparative study, the effective order for aniline rejection is: HR98PP > NF97 > DESAL3B > SEPA-MS05 > NF99HF.

Remediation of hydrocarbon-contaminated soils by ex situ microwave treatment: technical, energy and economic considerations.

PubMed

Falciglia, P P; Vagliasindi, F G A

2014-01-01

In this study, the remediation of diesel-polluted soils was investigated by simulating an ex situ microwave (MW) heating treatment under different conditions, including soil moisture, operating power and heating duration. Based on experimental data, a technical, energy and economic assessment for the optimization of full-scale remediation activities was carried out. Main results show that the operating power applied significantly influences the contaminant removal kinetics and the moisture content in soil has a major effect on the final temperature reachable during MW heating. The first-order kinetic model showed an excellent correlation (r2 > 0.976) with the experimental data for residual concentration at all operating powers and for all soil moistures tested. Excellent contaminant removal values up to 94.8% were observed for wet soils at power higher than 600 W for heating duration longer than 30 min. The use of MW heating with respect to a conventional ex situ thermal desorption treatment could significantly decrease the energy consumption needed for the removal of hydrocarbon contaminants from soils. Therefore, the MW treatment could represent a suitable cost-effective alternative to the conventional thermal treatment for the remediation of hydrocarbon-polluted soil.

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.

Removal of Cu2+ and turbidity from wastewater by mercaptoacetyl chitosan.

PubMed

Chang, Qing; Zhang, Min; Wang, Jinxi

2009-09-30

A macromolecule heavy metal flocculant mercaptoacetyl chitosan (MAC) was prepared by reacting chitosan with mercaptoacetic acid. In preliminary experiments, the flocculation performance of MAC was evaluated by using wastewater containing Cu(2+) or/and turbidity. Some factors which affect the removal of Cu(2+) and turbidity were also studied. The experimental results showed that: (1) MAC can remove both Cu(2+) and turbidity from wastewater. The removal efficiency of Cu(2+) by using MAC combined with hydrolyzed polyacrylamide is higher than that by only using MAC, the removal efficiency of Cu(2+) reaches above 98%; (2) when water sample containing not only Cu(2+) but also turbidity-causing substance, the removal efficiency of both Cu(2+) and turbidity will be promoted by the cooperation effect of each other, the residual concentration of Cu(2+) reaches below 0.5 mg L(-1) and the turbidity reaches below 3NTU, Cu(2+) is more easily removed by MAC when turbidity is higher; (3) the removal efficiency of Cu(2+) increases with the increase in pH value, contrarily removal efficiency of turbidity decreases with the increase in pH value.

Exploring the effects of transducer models when training convolutional neural networks to eliminate reflection artifacts in experimental photoacoustic images

NASA Astrophysics Data System (ADS)

Allman, Derek; Reiter, Austin; Bell, Muyinatu

2018-02-01

We previously proposed a method of removing reflection artifacts in photoacoustic images that uses deep learning. Our approach generally relies on using simulated photoacoustic channel data to train a convolutional neural network (CNN) that is capable of distinguishing sources from artifacts based on unique differences in their spatial impulse responses (manifested as depth-based differences in wavefront shapes). In this paper, we directly compare a CNN trained with our previous continuous transducer model to a CNN trained with an updated discrete acoustic receiver model that more closely matches an experimental ultrasound transducer. These two CNNs were trained with simulated data and tested on experimental data. The CNN trained using the continuous receiver model correctly classified 100% of sources and 70.3% of artifacts in the experimental data. In contrast, the CNN trained using the discrete receiver model correctly classified 100% of sources and 89.7% of artifacts in the experimental images. The 19.4% increase in artifact classification accuracy indicates that an acoustic receiver model that closely mimics the experimental transducer plays an important role in improving the classification of artifacts in experimental photoacoustic data. Results are promising for developing a method to display CNN-based images that remove artifacts in addition to only displaying network-identified sources as previously proposed.

Experimental investigation of the formaldehyde removal mechanisms in a dynamic botanical filtration system for indoor air purification.

PubMed

Wang, Zhiqiang; Pei, Jingjing; Zhang, Jensen S

2014-09-15

Botanical filtration has been proved to be effective for indoor gas pollutant removal. To understand the roles of different transport, storage and removal mechanism by a dynamic botanical air filter, a series of experimental investigations were designed and conducted in this paper. Golden Pothos (Epipremnum aureum) plants was selected for test, and its original soil or activated/pebbles root bed was used in different test cases. It was found that flowing air through the root bed with microbes dynamically was essential to obtain meaningful formaldehyde removal efficiency. For static potted plant as normally place in rooms, the clean air delivery rate (CADR), which is often used to quantify the air cleaning ability of portable air cleaners, was only ∼ 5.1m(3)/h per m(2) bed, while when dynamically with air flow through the bed, the CADR increased to ∼ 233 m(3)/h per m(2) bed. The calculated CADR due to microbial activity is ∼ 108 m(3)/h per m(2) bed. Moisture in the root bed also played an important role, both for maintaining a favorable living condition for microbes and for absorbing water-soluble compounds such as formaldehyde. The role of the plant was to introduce and maintain a favorable microbe community which effectively degraded the volatile organic compounds adsorbed or absorbed by the root bed. The presence of the plant increased the removal efficiency by a factor of two based on the results from the bench-scale root bed experiments. Copyright © 2014 Elsevier B.V. All rights reserved.

Nucleic acid isolation

DOEpatents

Longmire, J.L.; Lewis, A.K.; Hildebrand, C.E.

1988-01-21

A method is provided for isolating DNA from eukaryotic cell and flow sorted chromosomes. When DNA is removed from chromosome and cell structure, detergent and proteolytic digestion products remain with the DNA. These products can be removed with organic extraction, but the process steps associated with organic extraction reduces the size of DNA fragments available for experimental use. The present process removes the waste products by dialyzing a solution containing the DNA against a solution containing polyethylene glycol (PEG). The waste products dialyze into the PEG leaving isolated DNA. The remaining DNA has been prepared with fragments containing more than 160 kb. The isolated DNA has been used in conventional protocols without effect on the protocol.

Effect of compost age and composition on the atrazine removal from solution.

PubMed

Tsui, Lo; Roy, William R

2007-01-02

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters.

Effect of compost age and composition on the atrazine removal from solution

USGS Publications Warehouse

Tsui, L.; Roy, W.R.

2007-01-01

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters. ?? 2006 Elsevier B.V. All rights reserved.

The Effects of Elaboration and Rehearsal on Long-Term Retention of Shape Names by Kindergarteners

ERIC Educational Resources Information Center

Gallimore, Ronald; And Others

1977-01-01

Elaboration and overt rehearsal are compared as instructional paradigms for memory retention. Superior long-term retention was produced in the elaboration condition when the initial acquisition effects were statistically removed. Short-term data suggest acquisition was complexly affected by experimental condition, I.Q., and task. Elaboration…

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

PubMed

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

2018-01-01

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

Effects of organic matter removal, soil compaction, and vegetation control on 5-year seedling performance: a regional comparison of long-term soil productivity sites

Treesearch

Robert L. Fleming; Robert F. Powers; Neil W. Foster; J. Marty Kranabetter; D. Andrew Scott; Felix Jr. Ponder; Shannon Berch; William K. Chapman; Richard D. Kabzems; Kim H. Ludovici; David M. Morris; Deborah S. Page-Dumroese; Paul T. Sanborn; Felipe G. Sanchez; Douglas M. Stone; Allan E. Tiarks

2006-01-01

We examined fifth-year seedling response to soil disturbance and vegetation control at 42 experimental locations representing 25 replicated studies within the North American Long-Term Soil Productivity (LTSP) program. These studies share a common experimental design while encompassing a wide range of climate, site conditions, and forest types. Whole-tree harvest had...

Testing ecological tradeoffs of a new tool for removing fine sediment in a spring-fed stream

USGS Publications Warehouse

Sepulveda, Adam; Sechrist, Juddson D.; Marczak, Laurie B

2014-01-01

Excessive fine sediment is a focus of stream restoration work because it can impair the structure and function of streams, but few methods exist for removing sediment in spring-fed streams. We tested a novel method of sediment removal with the potential to have minimal adverse effects on the biological community during the restoration process. The Sand Wand system, a dredgeless vacuum developed by Streamside Technologies, was used to experimentally remove fine sediment from Kackley Springs, a spring creek in southeastern Idaho. We assessed the effects of the Sand Wand on stream physical habitat and macroinvertebrate composition for up to 60 days after the treatment. We documented changes in multiple habitat variables, including stream depth, median particle size, and the frequency of embedded substrate in stream reaches that were treated with the Sand Wand. We also found that macroinvertebrate composition was altered even though common macroinvertebrate metrics changed little after the treatment. Our results suggest that the Sand Wand was effective at removing fine sediments in Kackley Springs and did minimal harm to macroinvertebrate function, but the Sand Wand was not ultimately effective in improving substrate composition to desired conditions. Additional restoration techniques are still needed to decrease the amount of fine sediment.

Stain removal effect of novel papain- and bromelain-containing gels applied to enamel.

PubMed

Münchow, Eliseu A; Hamann, Henry J; Carvajal, M Teresa; Pinal, Rodolfo; Bottino, Marco C

2016-11-01

The aims of the study are to prepare novel stain removal gel-based formulations containing papain or bromelain and to investigate their stain removal effect when applied to enamel. Experimental bromelain- and papain-based stain removal gels were prepared. Next, enamel/dentin tooth samples (6 × 6 mm 2 , 4 mm in thickness) were obtained from bovine teeth, stained in coffee solution for 1 week, and measured with a digital spectrophotometer (Easyshade, Vita Zahnfabrik) for color assessment (baseline). The samples were then randomly allocated into four groups (n = 7), according to the stain removal agent applied: ContrastPM+ (Discus Dental, LLC), which is based on 20 wt.% carbamide peroxide (positive control); bromelain-based; papain-based; and no agent (negative control). The materials were applied once a week, three times per day, during 4 weeks, and following the directions of use from positive control. The samples were measured again with the Easyshade and using the CIEL * a * b * color system. The color change (ΔE * ) results were obtained by subtracting the baseline values from the final color values obtained at each time point. The data were statistically analyzed using two-way repeated-measures analysis of variance and Student Newman Keuls's test as a post hoc test (α = 5 %). All stain removal agents produced greater color change than the negative control (p < .001), with the positive control demonstrating greater ΔE * values when compared to the experimental gels (p ≤ .004). The second application of all gels resulted in greater ΔE * values compared to the first application (p ≤ .025), although no color change was observed after the third application (p ≥ .051), regardless of the material evaluated. The proposed gels containing proteolytic enzymes (bromelain or papain) of vegetal origin may hold significant clinical potential as active agents for the preparation of stain removal agents free of hydrogen/carbamide peroxide.

77 FR 14061 - Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Northern Spotted Owl

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-08

... conservation. Experimental management of the barred owl threat is being addressed through a separate decision... move forward with a study on the experimental removal of barred owls. We will release the EIS for... experimental removal study, that decision will not include a determination on whether or how barred owls would...

Effect of adsorbent addition on floc formation and clarification.

PubMed

Younker, Jessica M; Walsh, Margaret E

2016-07-01

Adding adsorbent into the coagulation process is an emerging treatment solution for targeting hard-to-remove dissolved organic compounds from both drinking water and industrial wastewater. The impact of adding powdered activated carbon (PAC) or organoclay (OC) adsorbents with ferric chloride (FeCl3) coagulant was investigated in terms of potential changes to the coagulated flocs formed with respect to size, structure, and breakage and regrowth properties. The ability of dissolved air flotation (DAF) and sedimentation (SED) clarification processes to remove hybrid adsorbent-coagulant flocs was also evaluated through clarified water quality analysis of samples collected in bench-scale jar test experiments. The jar tests were conducted using both a synthetic fresh water and oily wastewater test water spiked with dissolved aromatic compounds phenol and naphthalene. Results of the study demonstrated that addition of adsorbent reduced the median coagulated floc size by up to 50% but did not affect floc strength or regrowth potential after application of high shear. Experimental results in fresh water demonstrated that sedimentation was more effective than DAF for clarification of both FeCl3-PAC and FeCl3-OC floc aggregates. However, experimental tests performed on the synthetic oily wastewater showed that coagulant-adsorbent floc aggregates were effectively removed with both DAF and sedimentation treatment, with lower residual turbidity achieved in clarified water samples than with coagulation treatment alone. Addition of OC or PAC into the coagulation process resulted in removals of over half, or nearly all of the dissolved aromatics, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Potassium Permanganate as an Alternative for Gold Mining Wastewater Treatment

NASA Astrophysics Data System (ADS)

Ordiales, M.; Fernández, D.; Verdeja, L. F.; Sancho, J.

2015-09-01

The feasibility of using potassium permanganate as a reagent for cyanide oxidation in wastewater was experimentally studied. Both artificial and production wastewater from two different gold mines were tested. The experiments had three goals: determine the optimum reagent concentration and reaction time required to achieve total cyanide removal, obtain knowledge of the reaction kinetics, and improve the management of the amount of reagent. The results indicate that potassium permanganate is an effective and reliable oxidizing agent for the removal of cyanide from gold mining wastewater.

Influence of Oxygen on Cu Distribution Behavior Between Molten Iron and FeS-Based Flux

NASA Astrophysics Data System (ADS)

Kang, Youngjo; Shin, Kil-Sun; Morita, Kazuki

2018-06-01

Cu distribution behavior between molten iron and a sulfide flux was investigated under different oxygen contents in the sulfide flux to clarify the effect of oxygen content in FeS-based flux on Cu removal. The activity coefficient of CuS0.5 could be experimentally estimated according to the oxygen content. Based on the present result, the possibility of Cu removal by sulfide flux containing a certain amount of oxide was discussed.

Plant functional types define magnitude of drought response in peatland CO2 exchange.

PubMed

Kuiper, Jan J; Mooij, Wolf M; Bragazza, Luca; Robroek, Bjorn J M

2014-01-01

Peatlands are important sinks for atmospheric carbon (C), yet the role of plant functional types (PFTs) for C sequestration under climatic perturbations is still unclear. A plant-removal experiment was used to study the importance of vascular PFTs for the net ecosystem CO2 exchange (NEE) during (i.e., resistance) and after (i.e., recovery) an experimental drought. The removal of PFTs caused a decrease of NEE, but the rate differed between microhabitats (i.e., hummocks and lawns) and the type of PFTs. Ericoid removal had a large effect on NEE in hummocks, while the graminoids played a major role in the lawns. The removal of PFTs did not affect the resistance or the recovery after the experimental drought. We argue that the response of Sphagnum mosses (the only PFT present in all treatments) to drought is dominant over that of coexisting PFTs. However, we observed that the moment in time when the system switched from C sink to C source during the drought was controlled by the vascular PFTs. In the light of climate change, the shifts in species composition or even the loss of certain PFTs are expected to strongly affect the future C dynamics in response to environmental stress.

Study on COD removal mechanism and reaction kinetics of oilfield wastewater.

PubMed

Yin, Xian-Qing; Jing, Bo; Chen, Wen-Juan; Zhang, Jian; Liu, Qian; Chen, Wu

2017-11-01

The chemical oxygen demand (COD) removal mechanism and reaction kinetics were mainly studied in the treatment of oilfield oily sewage containing polymer by three-dimensional electrode reactor. The results proved that the residual active oxides O 3 , H 2 O 2 , •OH and active chlorine in the system of electrochemical reaction could be effectively detected, and the COD removal mechanism was co-oxidation of active oxides; Under these experimental conditions: the electrolysis current of 6 A, surface/volume ratio of 6/25(cm 2 ·L -1 ), the reaction time of 50 min, the COD cr of treated sewage was no more than 50 mg·L -1 ; the removal reaction of COD conformed to apparent second-order reaction kinetic model, the correlation coefficient R 2 was 0.9728, and the apparent reaction rate constant was k = 3.58 × 10 -4 (L·min -1 ·mg -1 ·m -2 ). To reach the goal, the COD cr was no more than 50 mg·L -1 in treated sewage, and the theory minimum processing time was 45.73 min. The verification of experimental results was consistent with kinetic equations.

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.

Removal of millimeter-scale rolled edges using bevel-cut-like tool influence function in magnetorheological jet polishing.

PubMed

Yang, Hao; Cheng, Haobo; Feng, Yunpeng; Jing, Xiaoli

2018-05-01

Subaperture polishing techniques usually produce rolled edges due to edge effect. The rolled edges, especially those in millimeter scale on small components, are difficult to eliminate using conventional polishing methods. Magnetorheological jet polishing (MJP) offers the possibility of the removal of these structures, owing to its small tool influence function (TIF) size. Hence, we investigate the removal characters of inclined MJP jetting models by means of computational fluid dynamics (CFD) simulations and polishing experiments. A discrete phase model (DPM) is introduced in the simulation to get the influence of abrasive particle concentration on the removal mechanism. Therefore, a more accurate model for MJP removal mechanisms is built. With several critical problems solved, a small bevel-cut-like TIF (B-TIF), which has fine acentric and unimodal characteristics, is obtained through inclined jetting. The B-TIF proves to have little edge effect and is applied in surface polishing of thin rolled edges. Finally, the RMS of the experimental section profile converges from 10.5 nm to 1.4 nm, and the rolled edges are successfully suppressed. Consequently, it is validated that the B-TIF has remarkable ability in the removal of millimeter-scale rolled edges.

Study of Montmorillonite Clay for the Removal of Copper (II) by Adsorption: Full Factorial Design Approach and Cascade Forward Neural Network

PubMed Central

Turan, Nurdan Gamze; Ozgonenel, Okan

2013-01-01

An intensive study has been made of the removal efficiency of Cu(II) from industrial leachate by biosorption of montmorillonite. A 24 factorial design and cascade forward neural network (CFNN) were used to display the significant levels of the analyzed factors on the removal efficiency. The obtained model based on 24 factorial design was statistically tested using the well-known methods. The statistical analysis proves that the main effects of analyzed parameters were significant by an obtained linear model within a 95% confidence interval. The proposed CFNN model requires less experimental data and minimum calculations. Moreover, it is found to be cost-effective due to inherent advantages of its network structure. Optimization of the levels of the analyzed factors was achieved by minimizing adsorbent dosage and contact time, which were costly, and maximizing Cu(II) removal efficiency. The suggested optimum conditions are initial pH at 6, adsorbent dosage at 10 mg/L, and contact time at 10 min using raw montmorillonite with the Cu(II) removal of 80.7%. At the optimum values, removal efficiency was increased to 88.91% if the modified montmorillonite was used. PMID:24453833

Mercury removal from contaminated water by ultrasound-promoted reduction/vaporization in a microscale reactor.

PubMed

Gil, Sandra; Lavilla, Isela; Bendicho, Carlos

2008-03-01

A new method is described for the removal of Hg(II) at trace level from waters using an ultrasound-promoted reduction/volatilization process. The method is accomplished in a sonoreactor (100 W power; 20 kHz frequency) by adding formic acid to induce the reduction of Hg(II) to Hg(0). In contrast to other treatments, it does not introduce further foreign substances for water decontamination. A reduction mechanism is proposed, which relies on the sonolytic decomposition of formic acid to yield reducing gases such as H(2) and CO, which in turn, causes the reduction of Hg(II). After the formation of Hg(0), its removal is facilitated by the degassing effect caused by ultrasound irradiation. Hg at 100 ng/mL concentration can be removed within 30 min with a yield of 90% from a 10 mL water volume. The presence of stabilizing anions or oxidants in waters may preclude the Hg removal. Effects of experimental variables such as treatment time, amplitude of the ultrasonic probe vibration, formic acid concentration and sample volume were investigated.

Investigating the mechanism of clofibric acid removal in Fe(0)/H2O systems.

PubMed

Ghauch, Antoine; Abou Assi, Hala; Tuqan, Almuthanna

2010-04-15

Since the introduction of iron wall technology, the inherent relationship between contaminant removal and iron corrosion has been mostly attributed to electron transfer from the metal body (direct reduction). This thermodynamically founded premise has failed to explain several experimental facts. Recently, a new concept considering adsorption and co-precipitation as fundamental contaminant removal mechanisms was introduced. This consistent concept has faced very skeptic views and necessarily needs experimental validation. The present work was the first independent attempt to validate the new concept using clofibric acid (CLO) as model compound. For this purpose, a powdered Fe(0) material (Fe(0)) was used in CLO removal experiments under various experimental conditions. Additional experiments were performed with plated Fe(0) (mFe(0): Fe(0)/Pd(0), Fe(0)/Ni(0)) to support the discussion of removal mechanism. Main investigated experimental variables included: abundance of O(2), abundance of iron corrosion products (ICPs) and shaking operations. Results corroborated the concept that quantitative contaminant removal in Fe(0)/H(2)O systems occurs within the oxide-film in the vicinity of Fe(0). Additionally, mixing type and shaking intensity significantly influenced the extent of CLO removal. More importantly, HPLC/MS revealed that the identity of reaction products depends on the extent of iron corrosion or the abundance of ICPs. The investigation of the CLO/Fe(0)/H(2)O system disproved the popular view that direct reduction mediates contaminant removal in the presence of Fe(0). 2009 Elsevier B.V. All rights reserved.

Sex steroids do not affect muscle weight, oxidative metabolism or cytosolic androgen reception binding of functionally overloaded rat Plantaris muscles

NASA Technical Reports Server (NTRS)

Max, S. R.; Rance, N.

1983-01-01

The effects of sex steroids on muscle weight and oxidative capacity of rat planaris muscles subjected to functional overload by removal of synergistic muscles were investigated. Ten weeks after bilateral synergist removal, plantaris muscles were significantly hypertrophic compared with unoperated controls. After this period, the ability of the muscles to oxide three substrates of oxidative metabolism was assessed. Experimental procedures are discussed and results are presented herein. Results suggest a lack of beneficial effect of sex hormone status on the process of hypertrophy and on biochemical changes in overloaded muscle. Such findings are not consistent with the idea of synergistic effects of sex steroids and muscle usage.

Artificial intelligence and regression analysis for Cd(II) ion biosorption from aqueous solution by Gossypium barbadense waste.

PubMed

Fawzy, Manal; Nasr, Mahmoud; Nagy, Heba; Helmi, Shacker

2018-02-01

In this study, batch biosorption experiments were conducted to determine the removal efficiency of Cd(II) ion from aqueous solutions by Gossypium barbadense waste. The biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) connected with energy dispersive X-ray (EDX). The sorption mechanism was described by complexation/chelation of Cd 2+ with the functional groups of O-H, C=O, -COO-, and C-O, as well as, cation-exchange with Mg 2+ and K + . At initial Cd(II) ion concentration (C o ), 50 mg/L, the adsorption equilibrium of 89.2% was achieved after 15 min under the optimum experimental factors of pH 6.0, biosorbent dosage 10 g/L, and particle diameter 0.125-0.25 mm. Both Langmuir and Freundlich models fitted well to the sorption data, suggesting the co-existence of monolayer coverage along with heterogenous surface biosorption. Artificial neural network (ANN) with a structure of 5-10-1 was performed to predict the Cd(II) ion removal efficiency. The ANN model provided high fit (R 2 0.923) to the experimental data and indicated that C o was the most influential input. A pure-quadratic model was developed to determine the effects of experimental factors on Cd(II) ion removal efficiency, which indicated the limiting nature of pH and biosorbent dosage on Cd(II) adsorption. Based on the regression model (R 2 0.873), the optimum experimental factors were pH 7.61, biosorbent dosage 24.74 g/L, particle size 0.125-0.25 mm, and adsorption time 109.77 min, achieving Cd 2+ removal of almost 100% at C o 50 mg/L.

Experimental removal of subgingival calculus with the Er:YAG laser

NASA Astrophysics Data System (ADS)

Keller, Ulrich; Hibst, Raimund

1996-01-01

The purpose of this study was to evaluate the effects of the Er:YAG laser removal of subgingival calculi in periodontal treatment and to describe laser-induced cementum surface alterations. Freshly extracted human teeth with adherent plaques and mineralized calculi were laser treated using modified quartz fiber tips in direct contact to the root surface. For the fiber tip tested, the ablation threshold was 6.5 mJ. An effective removal of calculi was possible with 50 mJ resp. 150 mJ for a triple fiber. For the latter, a mass loss with a mean of about 5.1. mg/min was achieved. Histologic examinations of the cementum surface showed smoothed appearance alternately with rough depressions of the fiber tips, which can be discussed as a good precondition for periodontal tissue regeneration. Maximum temperature increase of 1.4 K was reached in the pulp, if an additional water irrigation was applied to the root surface. From these results it can be concluded that with the Er:YAG laser an effective removal of subgingival calculi can be performed without thermal risk for the pulp.

Exceptional selectivity for dissolved silicas in industrial waters using mixed oxides

DOE PAGES

Sasan, Koroush; Brady, Patrick V.; Krumhansl, James L.; ...

2017-11-07

The removal of silica, ubiquitous in produced and industrial waters, by novel mixed oxides is investigated in this present study. We have combined the advantage of high selectivity hydrotalcite (HTC, (Mg 6Al 2(OH) 16(CO 3)·4H 2O)), with large surface area of active alumina (AA, (Al 2O 3)) for effective removing of the dissolved silica from cooling tower water. The batch test results indicated the combined HTC/AA is a more effective method for removing silica from CTW than using each of HTC or AA separately. The silica uptake was confirmed by Fourier transform infrared (FTIR), and Energy dispersive spectroscopy (EDS). Ourmore » results indicate HTC/AA effectively removes silica from cooling tower water (CTW), even in the presence of large concentrations of competing anions, such as Cl -, NO 3 - HCO 3 -, CO 3 2- and SO 4 2-. The Single Path Flow Through (SPFT) tests confirmed to rapid uptake of silica by combined HTC/AA during column filtration. The experimental data of silica adsorption fit best to Freundlich isotherm model.« less

Exceptional selectivity for dissolved silicas in industrial waters using mixed oxides

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

Sasan, Koroush; Brady, Patrick V.; Krumhansl, James L.

The removal of silica, ubiquitous in produced and industrial waters, by novel mixed oxides is investigated in this present study. We have combined the advantage of high selectivity hydrotalcite (HTC, (Mg 6Al 2(OH) 16(CO 3)·4H 2O)), with large surface area of active alumina (AA, (Al 2O 3)) for effective removing of the dissolved silica from cooling tower water. The batch test results indicated the combined HTC/AA is a more effective method for removing silica from CTW than using each of HTC or AA separately. The silica uptake was confirmed by Fourier transform infrared (FTIR), and Energy dispersive spectroscopy (EDS). Ourmore » results indicate HTC/AA effectively removes silica from cooling tower water (CTW), even in the presence of large concentrations of competing anions, such as Cl -, NO 3 - HCO 3 -, CO 3 2- and SO 4 2-. The Single Path Flow Through (SPFT) tests confirmed to rapid uptake of silica by combined HTC/AA during column filtration. The experimental data of silica adsorption fit best to Freundlich isotherm model.« less

Silver removal from aqueous solution by biochar produced from biosolids via microwave pyrolysis.

PubMed

Antunes, Elsa; Jacob, Mohan V; Brodie, Graham; Schneider, Philip A

2017-12-01

The contamination of water with silver has increased due to the widespread applications of products with silver employed as antimicrobial agent. Adsorption is a cost-effective method for silver removal from aqueous solution. In this study biochar, produced from the microwave assisted pyrolysis of biosolids, was used for silver removal from an aqueous solution. The adsorption kinetics, isotherms and thermodynamics were investigated to better understand the silver removal process by biochar. X-ray diffraction results demonstrated that silver removal was a combination two consecutive mechanisms, reduction and physical adsorption. The Langmuir model fitted the experimental data well, showing that silver removal was predominantly a surface mechanism. The thermodynamic investigation demonstrated that silver removal by biochar was an exothermic process. The final nanocomposite Ag-biochar (biochar plus silver) was used for methylene blue adsorption and photodegradation. This study showed the potential of using biochar produced from biosolids for silver removal as a promising solution to mitigate water pollution and an environmentally sustainable approach for biosolids management and re-use. Copyright © 2017 Elsevier Ltd. All rights reserved.

Artificial Intelligence Based Optimization for the Se(IV) Removal from Aqueous Solution by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron Composites

PubMed Central

Cao, Rensheng; Ruan, Wenqian; Wu, Xianliang; Wei, Xionghui

2018-01-01

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites. Both GA and PSO were used to optimize the parameters of ANN. The effect of operational parameters (i.e., initial pH, temperature, contact time and initial Se(IV) concentration) on the removal efficiency was examined using response surface methodology (RSM), which was also utilized to obtain a dataset for the ANN training. The ANN-GA model results (with a prediction error of 2.88%) showed a better agreement with the experimental data than the ANN-PSO model results (with a prediction error of 4.63%) and the RSM model results (with a prediction error of 5.56%), thus the ANN-GA model was an ideal choice for modeling and optimizing the Se(IV) removal by the nZVI/rGO composites due to its low prediction error. The analysis of the experimental data illustrates that the removal process of Se(IV) obeyed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the Se 3d and 3p peaks found in XPS spectra for the nZVI/rGO composites after removing treatment illustrates that the removal of Se(IV) was mainly through the adsorption and reduction mechanisms. PMID:29543753

Artificial Intelligence Based Optimization for the Se(IV) Removal from Aqueous Solution by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron Composites.

PubMed

Cao, Rensheng; Fan, Mingyi; Hu, Jiwei; Ruan, Wenqian; Wu, Xianliang; Wei, Xionghui

2018-03-15

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites. Both GA and PSO were used to optimize the parameters of ANN. The effect of operational parameters (i.e., initial pH, temperature, contact time and initial Se(IV) concentration) on the removal efficiency was examined using response surface methodology (RSM), which was also utilized to obtain a dataset for the ANN training. The ANN-GA model results (with a prediction error of 2.88%) showed a better agreement with the experimental data than the ANN-PSO model results (with a prediction error of 4.63%) and the RSM model results (with a prediction error of 5.56%), thus the ANN-GA model was an ideal choice for modeling and optimizing the Se(IV) removal by the nZVI/rGO composites due to its low prediction error. The analysis of the experimental data illustrates that the removal process of Se(IV) obeyed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the Se 3d and 3p peaks found in XPS spectra for the nZVI/rGO composites after removing treatment illustrates that the removal of Se(IV) was mainly through the adsorption and reduction mechanisms.

Evaluation of Palatal Plate Thickness of Maxillary Prosthesis on Phonation- A Comparative Clinical Study

PubMed Central

B, Sreedevi; Anne, Gopinadh; Manne, Prakash; Bindu O, Swetha Hima; Atla, Jyothi; Deepthi, Sneha; Chaitanya A, Krishna

2014-01-01

Background: Prosthodontic treatment involves clinical procedures which influence speech performance directly or indirectly. Prosthetic rehabilitation of missing teeth with partial or complete maxillary removable dentures influences the individual voice characteristics like Phonation, resonance etc. Aim: To evaluate the effect of Acrylic palatal plate thickness (1mm-3mm) of maxillary prosthesis on phonation. Materials and Methods: Twelve subjects were selected randomly between the age group of 20-25 years who have full complement of teeth and have no speech problems. Speech evaluation was done under four experimental conditions i.e. Without any experimental acrylic palatal plate (control), with experimental acrylic palatal plates of thickness 1 mm, 2 mm and 3 mm respectively. The speech material for phonation test consisted of Vowels sounds /a/, /i/, and /o/. Speech analysis to assess phonation was done using digital acoustic analysis (PRAAT software). The obtained results were statistically analyzed by One-way ANOVA and Tukey’s multiple post-hoc for comparison of four experimental conditions with respect to different vowel sounds. Results: Mean harmonics to noise ratio (HNR) values obtained for all the Experimental conditions did not show significant difference (p>0.05). In conclusion, an increase in the thickness of the acrylic palatal plate of maxillary prosthesis for about 1 mm - 3mm in complete or partial maxillary removable dentures resulted in no significant effect on phonation of vowel sounds /a/, /i/ and /o/. Conclusion: Increasing the thickness of the palatal plate from 1 mm to 3 mm has not shown any significant effect on the phonation. PMID:24959508

Removal of fluorine from contaminated soil by electrokinetic treatment driven by solar energy.

PubMed

Zhou, Ming; Zhu, Shufa; Liu, Yana; Wang, Xuejian

2013-08-01

Instead of direct current power supply, a series of electrokinetic remediation experiments driven by solar energy on fluorine-contaminated soil were conducted in a self-made electrolyzer, in order to reduce energy expenditure of electrokinetic remediation. After the 12-day electrokinetic remediation driven by solar energy, the removal efficiency of fluorine was 22.3%, and electrokinetic treatment had an impact on changes in partitioning of fluorine in soil. It proved that the combination of electrokinetics and solar energy was feasible and effective to some extent for the remediation of fluorine-contaminated soil. Meanwhile, the experimental results also indicated that the electromigration was a more dominant transport mechanism for the removal of fluorine from contaminated soil than electroosmosis, and the weather condition was the important factor in affecting the removal efficiency.

Electrolytic decontamination of conductive materials for hazardous waste management

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

Wedman, D.E.; Martinez, H.E.; Nelson, T.O.

1996-12-31

Electrolytic removal of plutonium and americium from stainless steel and uranium surfaces has been demonstrated. Preliminary experiments were performed on the electrochemically based decontamination of type 304L stainless steel in sodium nitrate solutions to better understand the metal removal effects of varying cur-rent density, pH, and nitrate concentration parameters. Material removal rates and changes in surface morphology under these varying conditions are reported. Experimental results indicate that an electropolishing step before contamination removes surface roughness, thereby simplifying later electrolytic decontamination. Sodium nitrate based electrolytic decontamination produced the most uniform stripping of material at low to intermediate pH and at sodiummore » nitrate concentrations of 200 g L{sup -1} and higher. Stirring was also observed to increase the uniformity of the stripping process.« less

Impact of the experimental removal of lizards on Lyme disease risk.

PubMed

Swei, Andrea; Ostfeld, Richard S; Lane, Robert S; Briggs, Cheryl J

2011-10-07

The distribution of vector meals in the host community is an important element of understanding and predicting vector-borne disease risk. Lizards (such as the western fence lizard; Sceloporus occidentalis) play a unique role in Lyme disease ecology in the far-western United States. Lizards rather than mammals serve as the blood meal hosts for a large fraction of larval and nymphal western black-legged ticks (Ixodes pacificus--the vector for Lyme disease in that region) but are not competent reservoirs for the pathogen, Borrelia burgdorferi. Prior studies have suggested that the net effect of lizards is to reduce risk of human exposure to Lyme disease, a hypothesis that we tested experimentally. Following experimental removal of lizards, we documented incomplete host switching by larval ticks (5.19%) from lizards to other hosts. Larval tick burdens increased on woodrats, a competent reservoir, but not on deer mice, a less competent pathogen reservoir. However, most larvae failed to find an alternate host. This resulted in significantly lower densities of nymphal ticks the following year. Unexpectedly, the removal of reservoir-incompetent lizards did not cause an increase in nymphal tick infection prevalence. The net result of lizard removal was a decrease in the density of infected nymphal ticks, and therefore a decreased risk to humans of Lyme disease. Our results indicate that an incompetent reservoir for a pathogen may, in fact, increase disease risk through the maintenance of higher vector density and therefore, higher density of infected vectors.

Nitrogen Removal Characteristics of Pseudomonas putida Y-9 Capable of Heterotrophic Nitrification and Aerobic Denitrification at Low Temperature.

PubMed

Xu, Yi; He, Tengxia; Li, Zhenlun; Ye, Qing; Chen, Yanli; Xie, Enyu; Zhang, Xue

2017-01-01

The cold-adapted bacterium Pseudomonas putida Y-9 was investigated and exhibited excellent capability for nitrogen removal at 15°C. The strain capable of heterotrophic nitrification and aerobic denitrification could efficiently remove ammonium, nitrate, and nitrite at an average removal rate of 2.85 mg, 1.60 mg, and 1.83 mg NL -1  h -1 , respectively. Strain Y-9 performed nitrification in preference to denitrification when ammonium and nitrate or ammonium and nitrite coexisted in the solution. Meantime, the presence of nitrate had no effect on the ammonium removal rate of strain Y-9, and yet the presence of high concentration of nitrite would inhibit the cell growth and decrease the nitrification rate. The experimental results indicate that P. putida Y-9 has potential application for the treatment of wastewater containing high concentrations of ammonium along with its oxidation products at low temperature.

An improved artifact removal in exposure fusion with local linear constraints

NASA Astrophysics Data System (ADS)

Zhang, Hai; Yu, Mali

2018-04-01

In exposure fusion, it is challenging to remove artifacts because of camera motion and moving objects in the scene. An improved artifact removal method is proposed in this paper, which performs local linear adjustment in artifact removal progress. After determining a reference image, we first perform high-dynamic-range (HDR) deghosting to generate an intermediate image stack from the input image stack. Then, a linear Intensity Mapping Function (IMF) in each window is extracted based on the intensities of intermediate image and reference image, the intensity mean and variance of reference image. Finally, with the extracted local linear constraints, we reconstruct a target image stack, which can be directly used for fusing a single HDR-like image. Some experiments have been implemented and experimental results demonstrate that the proposed method is robust and effective in removing artifacts especially in the saturated regions of the reference image.

Removal of pharmaceutically active compounds in nitrifying-denitrifying plants.

PubMed

Suárez, S; Ramil, M; Omil, F; Lema, J M

2005-01-01

The behaviour of nine pharmaceutically active compounds (PhACs) of different diagnostic groups is studied during a nitrifying-denitrifying process in an activated sludge system. The compounds selected cover a wide range of frequently used substances such as anti-epileptics (carbamazepine), tranquillisers (diazepam), anti-depressants (fluoxetine and citalopram), anti-inflammatories (ibuprofen, naproxen and diclofenac) and estrogens (estradiol and ethinylestradiol). The main objective of this research is to investigate the effect of acclimation of biomass on the removal rates of these compounds, either by maintaining a high sludge retention time or at long-term operation. The removal rates achieved for nitrogen and carbon in the experimental unit exceed 90% and were not affected by the addition of PhACs. Carbamazepine, diazepam and diclofenac were only removed to a small extent. On the other hand, higher removal rates have been observed for naproxen and ibuprofen (68% and 82%), respectively.

Arsenic uptake by Lemna minor in hydroponic system.

PubMed

Goswami, Chandrima; Majumder, Arunabha; Misra, Amal Kanti; Bandyopadhyay, Kaushik

2014-01-01

Arsenic is hazardous and causes several ill effects on human beings. Phytoremediation is the use of aquatic plants for the removal of toxic pollutants from external media. In the present research work, the removal efficiency as well as the arsenic uptake capacity of duckweed Lemna minor has been studied. Arsenic concentration in water samples and plant biomass were determined by AAS. The relative growth factor of Lemna minor was determined. The duckweed had potential to remove as well as uptake arsenic from the aqueous medium. Maximum removal of more than 70% arsenic was achieved atinitial concentration of 0.5 mg/1 arsenic on 15th day of experimental period of 22 days. Removal percentage was found to decrease with the increase in initial concentration. From BCF value, Lemna minor was found to be a hyperaccumulator of arsenic at initial concentration of 0.5 mg/L, such that accumulation decreased with increase in initial arsenic concentration.

Llama heavy-chain antibody fragments efficiently remove toxic shock syndrome toxin 1 from plasma in vitro but not in experimental porcine septic shock.

PubMed

Brummelhuis, Walter J; Joles, Jaap A; Stam, Jord C; Adams, Hendrik; Goldschmeding, Roel; Detmers, Frank J; El Khattabi, Mohamed; Maassen, Bram T; Verrips, C Theo; Braam, Branko

2010-08-01

Staphylococcus aureus produces the superantigen toxic shock syndrome toxin 1 (TSST-1). When the bacterium invades the human circulation, this toxin can induce life-threatening gram-positive sepsis. Current sepsis treatment does not remove bacterial toxins. Variable domains of llama heavy-chain antibodies (VHH) against toxic shock syndrome toxin 1 ([alpha]-TSST-1 VHH) were previously found to be effective in vitro. We hypothesized that removing TSST-1 with [alpha]-TSST-1 VHH hemofiltration filters would ameliorate experimental sepsis in pigs. After assessing in vitro whether timely removing TSST-1 interrupted TSST-1-induced mononuclear cell TNF-[alpha] production, VHH-coated filters were applied in a porcine sepsis model. Clinical course, survival, plasma interferon [gamma], and TSST-1 levels were similar with and without VHH-coated filters as were TSST-1 concentrations before and after the VHH filter. Plasma TSST-1 levels were much lower than anticipated from the distribution of the amount of infused TSST-1, suggesting compartmentalization to space or adhesion to surface not accessible to hemofiltration or pheresis techniques. Removing TSST-1 from plasma was feasible in vitro. However, the [alpha]-TSST-1 VHH adsorption filter-based technique was ineffective in vivo, indicating that improvement of VHH-based hemofiltration is required. Sequestration likely prevented the adequate removal of TSST-1. The latter warrants further investigation of TSST-1 distribution and clearance in vivo.

Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal.

PubMed

Madarati, A A; Qualtrough, A J E; Watts, D C

2010-11-01

To investigate the effect of retained fractured endodontic instruments on root strength and to evaluate the effectiveness of several root filling materials in reinforcing roots that had undergone unsuccessful attempt at removal of fractured instruments. Seventy five mandibular premolar roots were divided into five groups. In group A (control), canals were prepared to a size F5-ProTaper instrument and filled with gutta-percha and TubliSeal sealer fragments. In the experimental groups (B, C, D and E), 4 mm of F5-ProTaper instruments were fractured in the apical one-third of the canal and then treated as follows: in group B, the fragments were left in situ without attempt at removal, and canals were filled with gutta-percha and TubliSeal sealer (GP No Removal). In groups C, D and E, an attempt at removal of the fragment was simulated by preparing a staging platform coronal to the fragment using modified Gates Glidden burs (No 2-5). Canals in group C were filled with gutta-percha and TubliSeal sealer (GP Removal), group D filled with Resilon (Resilon Removal) and group E with mineral trioxide aggregate (MTA Removal). Roots then underwent vertical fracture. Data were analysed using the one-way anova at P<0.05. Roots in the GP Removal group had significantly lower values for mean force for fracture (404.9 N). There was no significant difference between the control group and GP No Removal (765.2 and 707.8, respectively). Resilon Removal and MTA Removal groups (577.3 and 566.6 N) were not significantly different from the GP No Removal group. Leaving fractured instruments in the apical one-third of the canal does not appear to affect the resistance of the root to vertical fracture; Resilon and MTA appear to compensate for root dentine loss that occurred as a consequence of attempts at retrieval of fractured instruments when used as canal filling materials. © 2010 International Endodontic Journal.

Fiber laser cleaning of metal mirror surfaces for optical diagnostic systems of the ITER

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

Kuznetsov, A. P., E-mail: APKuznetsov@mephi.ru; Alexandrova, A. S.; Buzhinsky, O. I.

2015-12-15

The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 10{sup 7} W/cm{sup 2}. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant.

Experimental evaluation of blockage ratio and plenum evacuation system flow effects on pressure distribution for bodies of revolution in 0.1 scale model test section of NASA Lewis Research Center's proposed altitude wind tunnel

NASA Technical Reports Server (NTRS)

Burley, Richard R.; Harrington, Douglas E.

1987-01-01

An experimental investigation was conducted in the slotted test section of the 0.1-scale model of the proposed Altitude Wind Tunnel to evaluate wall interference effects at tunnel Mach numbers from 0.70 to 0.95 on bodies of revolution with blockage rates of 0.43, 3, 6, and 12 percent. The amount of flow that had to be removed from the plenum chamber (which surrounded the slotted test section) by the plenum evacuation system (PES) to eliminate wall interference effects was determined. The effectiveness of tunnel reentry flaps in removing flow from the plenum chamber was examined. The 0.43-percent blockage model was the only one free of wall interference effects with no PES flow. Surface pressures on the forward part of the other models were greater than interference-free results and were not influenced by PES flow. Interference-free results were achieved on the aft part of the 3- and 6-percent blockage models with the proper amount of PES flow. The required PES flow was substantially reduced by opening the reentry flaps.

Is halogen content the most important factor in the removal of halogenated trace organics by MBR treatment?

PubMed

Hai, Faisal I; Tadkaew, Nichanan; McDonald, James A; Khan, Stuart J; Nghiem, Long D

2011-05-01

This study investigated the relationship between physicochemical properties (namely halogen content and hydrophobicity) of halogenated trace organics and their removal efficiencies by a laboratory scale membrane bioreactor (MBR) under stable operating conditions. The reported results demonstrated a combined effect of halogen content and hydrophobicity on the removal. Compounds with high halogen content (>0.3) were well removed (>85%) when they possessed high hydrophobicity (Log D>3.2), while those with lower Log D values were also well removed if they had low halogen content (<0.1). General indices such as the BIOWIN index (which is based on only biodegradation) or a more specific index such as the halogen content (which captures a chemical aspect) appeared insufficient to predict the removal efficiency of halogenated compounds in MBR. Experimental data confirmed that the ratio of halogen content and Log D, which incorporates two important physico-chemical properties, is comparatively more suitable. Copyright © 2011 Elsevier Ltd. All rights reserved.

Rapid Adsorption of Heavy Metals by Fe3O4/Talc Nanocomposite and Optimization Study Using Response Surface Methodology

PubMed Central

Kalantari, Katayoon; Ahmad, Mansor B.; Masoumi, Hamid Reza Fard; Shameli, Kamyar; Basri, Mahiran; Khandanlou, Roshanak

2014-01-01

Fe3O4/talc nanocomposite was used for removal of Cu(II), Ni(II), and Pb(II) ions from aqueous solutions. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the variables. The adsorption parameters such as adsorbent dosage, removal time, and initial ion concentration were used as the independent variables and their effects on heavy metal ion removal were investigated. Analysis of variance was incorporated to judge the adequacy of the models. Optimal conditions with initial heavy metal ion concentration of 100, 92 and 270 mg/L, 120 s of removal time and 0.12 g of adsorbent amount resulted in 72.15%, 50.23%, and 91.35% removal efficiency for Cu(II), Ni(II), and Pb(II), respectively. The predictions of the model were in good agreement with experimental results and the Fe3O4/talc nanocomposite was successfully used to remove heavy metals from aqueous solutions. PMID:25050784

Rapid adsorption of heavy metals by Fe3O4/talc nanocomposite and optimization study using response surface methodology.

PubMed

Kalantari, Katayoon; Ahmad, Mansor B; Masoumi, Hamid Reza Fard; Shameli, Kamyar; Basri, Mahiran; Khandanlou, Roshanak

2014-07-21

Fe3O4/talc nanocomposite was used for removal of Cu(II), Ni(II), and Pb(II) ions from aqueous solutions. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the variables. The adsorption parameters such as adsorbent dosage, removal time, and initial ion concentration were used as the independent variables and their effects on heavy metal ion removal were investigated. Analysis of variance was incorporated to judge the adequacy of the models. Optimal conditions with initial heavy metal ion concentration of 100, 92 and 270 mg/L, 120 s of removal time and 0.12 g of adsorbent amount resulted in 72.15%, 50.23%, and 91.35% removal efficiency for Cu(II), Ni(II), and Pb(II), respectively. The predictions of the model were in good agreement with experimental results and the Fe3O4/talc nanocomposite was successfully used to remove heavy metals from aqueous solutions.

Biosorption of Congo Red from aqueous solution onto burned root of Eichhornia crassipes biomass

NASA Astrophysics Data System (ADS)

Roy, Tapas Kumar; Mondal, Naba Kumar

2017-07-01

Biosorption is becoming a promising alternative to replace or supplement the present dye removal processes from dye containing waste water. In this work, adsorption of Congo Red (CR) from aqueous solution on burned root of Eichhornia crassipes ( BREC) biomass was investigated. A series of batch experiments were performed utilizing BREC biomass to remove CR dye from aqueous systems. Under optimized batch conditions, the BREC could remove up to 94.35 % of CR from waste water. The effects of operating parameters such as initial concentration, pH, adsorbent dose and contact time on the adsorption of CR were analyzed using response surface methodology. The proposed quadratic model for central composite design fitted very well to the experimental data. Response surface plots were used to determine the interaction effects of main factors and optimum conditions of the process. The optimum adsorption conditions were found to be initial CR concentration = 5 mg/L-1, pH = 7, adsorbent dose = 0.125 g and contact time = 45 min. The experimental isotherms data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm equations and the results indicated that the Freundlich isotherm showed a better fit for CR adsorption. Thermodynamic parameters were calculated from Van't Hoff plot, confirming that the adsorption process was spontaneous and exothermic. The high CR adsorptive removal ability and regeneration efficiency of this adsorbent suggest its applicability in industrial/household systems and data generated would help in further upscaling of the adsorption process.

Optimizing Cu(II) removal from aqueous solution by magnetic nanoparticles immobilized on activated carbon using Taguchi method.

PubMed

Ebrahimi Zarandi, Mohammad Javad; Sohrabi, Mahmoud Reza; Khosravi, Morteza; Mansouriieh, Nafiseh; Davallo, Mehran; Khosravan, Azita

2016-01-01

This study synthesized magnetic nanoparticles (Fe(3)O(4)) immobilized on activated carbon (AC) and used them as an effective adsorbent for Cu(II) removal from aqueous solution. The effect of three parameters, including the concentration of Cu(II), dosage of Fe(3)O(4)/AC magnetic nanocomposite and pH on the removal of Cu(II) using Fe(3)O(4)/AC nanocomposite were studied. In order to examine and describe the optimum condition for each of the mentioned parameters, Taguchi's optimization method was used in a batch system and L9 orthogonal array was used for the experimental design. The removal percentage (R%) of Cu(II) and uptake capacity (q) were transformed into an accurate signal-to-noise ratio (S/N) for a 'larger-the-better' response. Taguchi results, which were analyzed based on choosing the best run by examining the S/N, were statistically tested using analysis of variance; the tests showed that all the parameters' main effects were significant within a 95% confidence level. The best conditions for removal of Cu(II) were determined at pH of 7, nanocomposite dosage of 0.1 gL(-1) and initial Cu(II) concentration of 20 mg L(-1) at constant temperature of 25 °C. Generally, the results showed that the simple Taguchi's method is suitable to optimize the Cu(II) removal experiments.

Fractional Factorial Design Study on the Performance of GAC-Enhanced Electrocoagulation Process Involved in Color Removal from Dye Solutions.

PubMed

Secula, Marius Sebastian; Cretescu, Igor; Cagnon, Benoit; Manea, Liliana Rozemarie; Stan, Corneliu Sergiu; Breaban, Iuliana Gabriela

2013-07-10

The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted using a two-level fractional factorial design ( FFD ) for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m²), initial pH of aqueous dye solution (3 or 9), electrocoagulation time (20 or 180 min), GAC dose (0.1 or 0.5 g/L), support electrolyte (2 or 50 mM), initial dye concentration (0.05 or 0.25 g/L) and current type (Direct Current- DC or Alternative Pulsed Current- APC ). GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method.

Fractional Factorial Design Study on the Performance of GAC-Enhanced Electrocoagulation Process Involved in Color Removal from Dye Solutions

PubMed Central

Secula, Marius Sebastian; Cretescu, Igor; Cagnon, Benoit; Manea, Liliana Rozemarie; Stan, Corneliu Sergiu; Breaban, Iuliana Gabriela

2013-01-01

The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted using a two-level fractional factorial design (FFD) for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m2), initial pH of aqueous dye solution (3 or 9), electrocoagulation time (20 or 180 min), GAC dose (0.1 or 0.5 g/L), support electrolyte (2 or 50 mM), initial dye concentration (0.05 or 0.25 g/L) and current type (Direct Current—DC or Alternative Pulsed Current—APC). GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method. PMID:28811405

Dental plaque removal with a novel battery-powered toothbrush.

PubMed

Biesbrock, Aaron R; Walters, Patricia; Bartizek, Robert D; Ruhlman, Douglas; Donly, Kevin J

2002-04-01

To compare the plaque removal efficacy of a positive control power toothbrush (Oral-B Ultra Plaque Remover) to an experimental power toothbrush (Crest SpinBrush) following a single use. This study was a randomized, controlled, examiner-blind, 2-period crossover design which examined plaque removal with the two toothbrushes following a single use in 38 completed subjects. Plaque was scored before and after brushing using the Turesky Modification of the Quigley-Hein Index. Baseline plaque scores were 1.89 and 1.91 for the experimental toothbrush and control toothbrush treatment groups, respectively. With respect to all surfaces examined, the experimental toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.46 while the control toothbrush delivered an adjusted mean difference of 0.45. These results were not statistically significant (P=0.645). A 95% one-sided upper confidence limit on the Ultra Plaque Remover minus SpinBrush difference in amount of plaque removed was calculated as 9.4% of the Ultra Plaque Remover adjusted mean. A common criterion for what is known as an "at least as good as" test is that the 95% one-sided confidence limit on the product difference is below 10% of the control product mean. Using this criterion, the SpinBrush is at least as good as the Oral-B Ultra Plaque Remover. With respect to buccal and lingual surfaces, the experimental toothbrush delivered very similar results relative to the control toothbrush. These results were also not statistically significant (P> 0.564).

Biofilm formation in an experimental water distribution system: the contamination of non-touch sensor taps and the implication for healthcare.

PubMed

Moore, Ginny; Stevenson, David; Thompson, Katy-Anne; Parks, Simon; Ngabo, Didier; Bennett, Allan M; Walker, Jimmy T

2015-01-01

Hospital tap water is a recognised source of Pseudomonas aeruginosa. U.K. guidance documents recommend measures to control/minimise the risk of P. aeruginosa in augmented care units but these are based on limited scientific evidence. An experimental water distribution system was designed to investigate colonisation of hospital tap components. P. aeruginosa was injected into 27 individual tap 'assemblies'. Taps were subsequently flushed twice daily and contamination levels monitored over two years. Tap assemblies were systematically dismantled and assessed microbiologically and the effect of removing potentially contaminated components was determined. P. aeruginosa was repeatedly recovered from the tap water at levels above the augmented care alert level. The organism was recovered from all dismantled solenoid valves with colonisation of the ethylene propylene diene monomer (EPDM) diaphragm confirmed by microscopy. Removing the solenoid valves reduced P. aeruginosa counts in the water to below detectable levels. This effect was immediate and sustained, implicating the solenoid diaphragm as the primary contamination source.

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface.

PubMed

Sharp, B; Morton, D; Clark, A E

2000-12-01

Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials. This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture. Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage. Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05). Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Magnetic hydroxyapatite nanoparticles: an efficient adsorbent for the separation and removal of nitrate and nitrite ions from environmental samples.

PubMed

Ghasemi, Ensieh; Sillanpää, Mika

2015-01-01

A novel type of magnetic nanosorbent, hydroxyapatite-coated Fe2O3 nanoparticles was synthesized and used for the adsorption and removal of nitrite and nitrate ions from environmental samples. The properties of synthesized magnetic nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction. After the adsorption process, the separation of γ-Fe2O3@hydroxyapatite nanoparticles from the aqueous solution was simply achieved by applying an external magnetic field. The effects of different variables on the adsorption efficiency were studied simultaneously using an experimental design. The variables of interest were amount of magnetic hydroxyapatite nanoparticles, sample volume, pH, stirring rate, adsorption time, and temperature. The experimental parameters were optimized using a Box-Behnken design and response surface methodology after a Plackett-Burman screening design. Under the optimum conditions, the adsorption efficiencies of magnetic hydroxyapatite nanoparticles adsorbents toward NO3(-) and NO2(-) ions (100 mg/L) were in the range of 93-101%. The results revealed that the magnetic hydroxyapatite nanoparticles adsorbent could be used as a simple, efficient, and cost-effective material for the removal of nitrate and nitrite ions from environmental water and soil samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predicting adsorptive removal of chlorophenol from aqueous solution using artificial intelligence based modeling approaches.

PubMed

Singh, Kunwar P; Gupta, Shikha; Ojha, Priyanka; Rai, Premanjali

2013-04-01

The research aims to develop artificial intelligence (AI)-based model to predict the adsorptive removal of 2-chlorophenol (CP) in aqueous solution by coconut shell carbon (CSC) using four operational variables (pH of solution, adsorbate concentration, temperature, and contact time), and to investigate their effects on the adsorption process. Accordingly, based on a factorial design, 640 batch experiments were conducted. Nonlinearities in experimental data were checked using Brock-Dechert-Scheimkman (BDS) statistics. Five nonlinear models were constructed to predict the adsorptive removal of CP in aqueous solution by CSC using four variables as input. Performances of the constructed models were evaluated and compared using statistical criteria. BDS statistics revealed strong nonlinearity in experimental data. Performance of all the models constructed here was satisfactory. Radial basis function network (RBFN) and multilayer perceptron network (MLPN) models performed better than generalized regression neural network, support vector machines, and gene expression programming models. Sensitivity analysis revealed that the contact time had highest effect on adsorption followed by the solution pH, temperature, and CP concentration. The study concluded that all the models constructed here were capable of capturing the nonlinearity in data. A better generalization and predictive performance of RBFN and MLPN models suggested that these can be used to predict the adsorption of CP in aqueous solution using CSC.

Effects of brash removal after clear felling on soil and soil-solution chemistry and field-layer biomass in an experimental nitrogen gradient.

PubMed

Ring, E; Högbom, L; Nohrstedt, H O

2001-10-12

Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha(-1). Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha(-1). Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3- content in the humus layer after clear felling. A decrease in the NO3- concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3- content for the highest N dose after clear felling ( p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation.

Nutrient balancing for phytoremediation enhancement of urea manufacturing raw wastewater.

PubMed

Yavari, Sara; Malakahmad, Amirhossein; Sapari, Nasiman B; Yavari, Saba; Khan, Eakalak

2017-11-01

Application of urea manufacturing wastewater to teak (Tectona grandis) trees, a fast growing tropical timber plants, is an environmentally-friendly and cost-effective alternative for treatment of nitrogen-rich wastewater. However, the plant growth is strongly limited by lack of phosphorus (P) and potassium (K) elements when the plants are irrigated with wastewater containing high concentration of nitrogen (N). A greenhouse experiment was conducted to optimize the efficiency of teak-based remediation systems in terms of nutrient balance. Twelve test solutions consisted of 4 levels of P (95, 190, 570, 1140 mgL -1 ) and 3 levels of K (95, 190, 570 mgL -1 ) with a constant level of N (190 mgL -1 ) were applied to teak seedlings every four days during the study period. Evapotranspiration rate, nutrient removal percentage, leaf surface area, dry weight and nutrient contents of experimental plants were determined and compared with those grown in control solution containing only N (N:P:K = 1:0:0). Teak seedlings grown in units with 1:0.5:1 N:P:K ratio were highly effective at nutrient removal upto 47%, 48% and 49% for N, P and K, respectively. Removal efficiency of teak plants grown in other experimental units decreased with increasing P and K concentrations in test solutions. The lowest nutrient removal and plant growth were recorded in units with 1:6:0.5 N:P:K ratio which received the highest ratio of P to K. The findings indicated that teak seedlings functioned effectively as phytoremediation plants for N-rich wastewater treatment when they were being supplied with proper concentrations of P and K. Copyright © 2017. Published by Elsevier Ltd.

Removal of batch effects using distribution-matching residual networks.

PubMed

Shaham, Uri; Stanton, Kelly P; Zhao, Jun; Li, Huamin; Raddassi, Khadir; Montgomery, Ruth; Kluger, Yuval

2017-08-15

Sources of variability in experimentally derived data include measurement error in addition to the physical phenomena of interest. This measurement error is a combination of systematic components, originating from the measuring instrument and random measurement errors. Several novel biological technologies, such as mass cytometry and single-cell RNA-seq (scRNA-seq), are plagued with systematic errors that may severely affect statistical analysis if the data are not properly calibrated. We propose a novel deep learning approach for removing systematic batch effects. Our method is based on a residual neural network, trained to minimize the Maximum Mean Discrepancy between the multivariate distributions of two replicates, measured in different batches. We apply our method to mass cytometry and scRNA-seq datasets, and demonstrate that it effectively attenuates batch effects. our codes and data are publicly available at https://github.com/ushaham/BatchEffectRemoval.git. yuval.kluger@yale.edu. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Experimental study and simulation of phosphorus purification effects of bioretention systems on urban surface runoff

PubMed Central

Liang, Zheng; Li, Yajiao; Li, Peng; Jiang, Chunbo

2018-01-01

Excessive phosphorus (P) contributes to eutrophication by degrading water quality and limiting human use of water resources. Identifying economic and convenient methods to control soluble reactive phosphorus (SRP) pollution in urban runoff is the key point of rainwater management strategies. Through three series of different tests involving influencing factors, continuous operation and intermittent operation, this study explored the purification effects of bioretention tanks under different experimental conditions, it included nine intermittent tests, single field continuous test with three groups of different fillers (Fly ash mixed with sand, Blast furnace slag, and Soil), and eight intermittent tests with single filler (Blast furnace slag mixed with sand). Among the three filler combinations studied, the filler with fly ash mixed with sand achieved the best pollution reduction efficiency. The setting of the submerged zone exerted minimal influence on the P removal of the three filler combinations. An extension of the dry period slightly promoted the P purification effect. The combination of fly ash mixed with sand demonstrated a positive purification effect on SRP during short- or long-term simulated rainfall duration. Blast furnace slag also presented a positive purification effect in the short term, although its continuous purification effect on SRP was poor in the long term. The purification abilities of soil in the short and long terms were weak. Under intermittent operations across different seasons, SRP removal was unstable, and effluent concentration processes were different. The purification effect of the bioretention system on SRP was predicted through partial least squares regression (PLS) modeling analysis. The event mean concentration removal of SRP was positively related to the adsorption capacity of filler and rainfall interval time and negatively related to submerged zones, influent concentration and volume. PMID:29742120

Paint removal from aluminum and composite substrate of aircraft by laser ablation using TEA CO2 lasers

NASA Astrophysics Data System (ADS)

Tsunemi, Akira; Endo, Akira; Ichishima, Daiji

1998-09-01

A high power TEA CO2 laser was applied to strip paints from the surface of aircraft. For our experimental samples, aluminum and fiber-reinforced composite substrate were painted as the completely same way as normal aircraft. As a result of delicate control of the irradiation parameters, the surfaces of not only aluminum substrate but also composite substrate were clearly exposed without any damages. Removed materials were found out to be effectively collected by a combination of a micro filter and activated carbon powder.

Application of response surface methodology for optimization of natural organic matter degradation by UV/H2O2 advanced oxidation process

PubMed Central

2014-01-01

Background In this research, the removal of natural organic matter from aqueous solutions using advanced oxidation processes (UV/H2O2) was evaluated. Therefore, the response surface methodology and Box-Behnken design matrix were employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as initial concentration of H2O2 (100–180 mg/L), pH (3–11), time (10–30 min) and initial total organic carbon (TOC) concentration (4–10 mg/L) were studied. Results Analysis of variance (ANOVA), revealed a good agreement between experimental data and proposed quadratic polynomial model (R2 = 0.98). Experimental results showed that with increasing H2O2 concentration, time and decreasing in initial TOC concentration, TOC removal efficiency was increased. Neutral and nearly acidic pH values also improved the TOC removal. Accordingly, the TOC removal efficiency of 78.02% in terms of the independent variables including H2O2 concentration (100 mg/L), pH (6.12), time (22.42 min) and initial TOC concentration (4 mg/L) were optimized. Further confirmation tests under optimal conditions showed a 76.50% of TOC removal and confirmed that the model is accordance with the experiments. In addition TOC removal for natural water based on response surface methodology optimum condition was 62.15%. Conclusions This study showed that response surface methodology based on Box-Behnken method is a useful tool for optimizing the operating parameters for TOC removal using UV/H2O2 process. PMID:24735555

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures.

PubMed

Ossareh, A; Rosentritt, M; Kishen, A

2018-01-01

The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test ( P < 0.05). Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group ( P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group ( P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups ( R 2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF.

Desulfurization of Coal in Fluidized Beds

NASA Technical Reports Server (NTRS)

Maddury, R.; Kalvinskas, J.

1985-01-01

Experimental dry chemical process for removing sulfur from coal-and thereby reducing harmful sulfur emissions from coal-fired electric powerplants-promises more economical and effective than older wet chemical processes. New process faster, requires smaller amounts of chemical reagents, and produces no liquid effluents, which poses disposal problem.

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.

Removal of phenol by activated alumina bed in pulsed high-voltage electric field.

PubMed

Zhu, Li-nan; Ma, Jun; Yang, Shi-dong

2007-01-01

A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe2+. The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/L Fe2+ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.

Concentration and time-dependent effect of initial sodium hypochlorite on the ability of QMix and ethylenediaminetetraacetic acid to remove smear layer.

PubMed

Aksel, Hacer; Serper, Ahmet

2017-01-01

The aim of this study was to compare the ability of 17% ethylenediaminetetraacetic acid (EDTA) and QMix with different concentrations and time exposures of initial sodium hypochlorite (NaOCl) to remove the smear layer from the root canals. Eighty maxillary central incisors were used. After instrumentation, the teeth were divided into eight experimental groups according to the initial and final rinse. About 2.5% and 5% NaOCl were used during instrumentation and for 1 or 3 min was used as postinstrumentation initial irrigants, and 17% EDTA and QMix used as final irrigants. The apical and middle parts of the specimens were observed by scanning electron microscope. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Friedman's test. Regardless of the type of final irrigant, QMix allowed more smear layer removal than EDTA after using 5% initial NaOCl for 3 min. In the apical part of the root canal walls, the smear layer was not completely removed. QMix and EDTA were similarly effective in smear layer removal at the middle parts of the root canal regardless of the concentration and time exposure of initial NaOCl, while none of the irrigation protocols was able to remove smear layer at the apical parts.

Removing lead from metallic mixture of waste printed circuit boards by vacuum distillation: factorial design and removal mechanism.

PubMed

Li, Xingang; Gao, Yujie; Ding, Hui

2013-10-01

The lead removal from the metallic mixture of waste printed circuit boards by vacuum distillation was optimized using experimental design, and a mathematical model was established to elucidate the removal mechanism. The variables studied in lead evaporation consisted of the chamber pressure, heating temperature, heating time, particle size and initial mass. The low-level chamber pressure was fixed at 0.1 Pa as the operation pressure. The application of two-level factorial design generated a first-order polynomial that agreed well with the data for evaporation efficiency of lead. The heating temperature and heating time exhibited significant effects on the efficiency, which was validated by means of the copper-lead mixture experiments. The optimized operating conditions within the region studied were the chamber pressure of 0.1 Pa, heating temperature of 1023 K and heating time of 120 min. After the conditions were employed to remove lead from the metallic mixture of waste printed circuit boards, the efficiency was 99.97%. The mechanism of the effects was elucidated by mathematical modeling that deals with evaporation, mass transfer and condensation, and can be applied to a wider range of metal removal by vacuum distillation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of photosynthetic efficacy and CO2 removal of microalgae grown in an enriched bicarbonate medium.

PubMed

Abinandan, S; Shanthakumar, S

2016-06-01

Bicarbonate species in the aqueous phase is the primary source for CO 2 for the growth of microalgae. The potential of carbon dioxide (CO 2 ) fixation by Chlorella pyrenoidosa in enriched bicarbonate medium was evaluated. In the present study, effects of parameters such as pH, sodium bicarbonate concentration and inoculum size were assessed for the removal of CO 2 by C. pyrenoidosa under mixotrophic condition. Central composite design tool from response surface methodology was used to validate statistical methods in order to study the influence of these parameters. The obtained results reveal that the maximum removal of CO 2 was attained at pH 8 with sodium bicarbonate concentration of 3.33 g/l, and inoculum size of 30 %. The experimental results were statistically significant with R 2 value of 0.9527 and 0.960 for CO 2 removal and accumulation of chlorophyll content, respectively. Among the various interactions, interactive effects between the parameters pH and inoculum size was statistically significant (P < 0.05) for CO 2 removal and chlorophyll accumulation. Based on the studies, the application of C. pyrenoidosa as a potential source for carbon dioxide removal at alkaline pH from bicarbonate source is highlighted.

Effects of Angle of Attack and Velocity on Trailing Edge Noise

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Brooks, Thomas F.

2006-01-01

Trailing edge (TE) noise measurements for a NACA 63-215 airfoil model are presented, providing benchmark experimental data for a cambered airfoil. The effects of flow Mach number and angle of attack of the airfoil model with different TE bluntnesses are shown. Far-field noise spectra and directivity are obtained using a directional microphone array. Standard and diagonal removal beamforming techniques are evaluated employing tailored weighting functions for quantitatively accounting for the distributed line character of TE noise. Diagonal removal processing is used for the primary database as it successfully removes noise contaminates. Some TE noise predictions are reported to help interpret the data, with respect to flow speed, angle of attack, and TE bluntness on spectral shape and peak levels. Important findings include the validation of a TE noise directivity function for different airfoil angles of attack and the demonstration of the importance of the directivity function s convective amplification terms.

Arsenic removal from water employing a combined system: photooxidation and adsorption.

PubMed

Lescano, Maia; Zalazar, Cristina; Brandi, Rodolfo

2015-03-01

A combined system employing photochemical oxidation (UV/H2O2) and adsorption for arsenic removal from water was designed and evaluated. In this work, a bench-scale photochemical annular reactor was developed being connected alternately to a pair of adsorption columns filled with titanium dioxide (TiO2) and granular ferric hydroxide (GFH). The experiences were performed by varying the relation of As concentration (As (III)/As (V) weight ratio) at constant hydrogen peroxide concentration and incident radiation. Experimental oxidation results were compared with theoretical predictions using an intrinsic kinetic model previously obtained. In addition, the effectiveness of the process was evaluated using a groundwater sample. The mathematical model of the entire system was developed. It could be used as an effective tool for the design and prediction of the behaviour of these types of systems. The combined technology is efficient and promising for arsenic removal to small and medium scale.

Clean Transfer of Wafer-Scale Graphene via Liquid Phase Removal of Polycyclic Aromatic Hydrocarbons.

PubMed

Kim, Hyun Ho; Kang, Boseok; Suk, Ji Won; Li, Nannan; Kim, Kwang S; Ruoff, Rodney S; Lee, Wi Hyoung; Cho, Kilwon

2015-05-26

Pentacene (C22H14), a polycyclic aromatic hydrocarbon, was used as both supporting and sacrificing layers for the clean and doping-free graphene transfer. After successful transfer of graphene to a target substrate, the pentacene layer was physically removed from the graphene surface by using intercalating organic solvent. This solvent-mediated removal of pentacene from graphene surface was investigated by both theoretical calculation and experimental studies with various solvents. The uses of pentacene and appropriate intercalation solvent enabled graphene transfer without forming a residue from the supporting layer. Such residues tend to cause charged impurity scattering and unintentional graphene doping effects. As a result, this clean graphene exhibited extremely homogeneous surface potential profiles over a large area. A field-effect transistor fabricated using this graphene displayed a high hole (electron) mobility of 8050 cm(2)/V·s (9940 cm(2)/V·s) with a nearly zero Dirac point voltage.

Fractional domain varying-order differential denoising method

NASA Astrophysics Data System (ADS)

Zhang, Yan-Shan; Zhang, Feng; Li, Bing-Zhao; Tao, Ran

2014-10-01

Removal of noise is an important step in the image restoration process, and it remains a challenging problem in image processing. Denoising is a process used to remove the noise from the corrupted image, while retaining the edges and other detailed features as much as possible. Recently, denoising in the fractional domain is a hot research topic. The fractional-order anisotropic diffusion method can bring a less blocky effect and preserve edges in image denoising, a method that has received much interest in the literature. Based on this method, we propose a new method for image denoising, in which fractional-varying-order differential, rather than constant-order differential, is used. The theoretical analysis and experimental results show that compared with the state-of-the-art fractional-order anisotropic diffusion method, the proposed fractional-varying-order differential denoising model can preserve structure and texture well, while quickly removing noise, and yields good visual effects and better peak signal-to-noise ratio.

Magnetic alginate beads for Pb(II) ions removal from wastewater.

PubMed

Bée, Agnès; Talbot, Delphine; Abramson, Sébastien; Dupuis, Vincent

2011-10-15

A magnetic adsorbent (called magsorbent) was developed by encapsulation of magnetic functionalized nanoparticles in calcium-alginate beads. The adsorption of Pb(II) ions by these magnetic beads was studied and the effect of different parameters, such as initial concentration, contact time and solution pH value on the adsorption of Pb(II) ions was investigated. Our magsorbent was found to be efficient to adsorb Pb(II) ions and maximal adsorption capacity occurred at pH 2.3-6. The classical Langmuir model used to fit the experimental adsorption data showed a maximum sorption capacity close to 100 mg g(-1). The experimental kinetic data were well correlated with a pseudo second-order model, 50% of the Pb(II) ions were removed within 20 min and the equilibrium was attained around 100 min. Moreover our magsorbent was easily collected from aqueous media by using an external magnetic field. These results permitted to conclude that magnetic alginate beads could be efficiently used to remove heavy metals in a water treatment process. Copyright © 2011 Elsevier Inc. All rights reserved.

Effects of experimental removal of barred owls on population demography of northern spotted owls in Washington and Oregon—2015 progress report

USGS Publications Warehouse

Wiens, J. David; Dugger, Katie M.; Lewicki, Krista E.; Simon, David C.

2016-03-14

Evidence indicates that competition with newly established barred owls (Strix varia) is causing rapid declines in populations of northern spotted owls (Strix occidentalis caurina), and that the longterm persistence of spotted owls may be in question without additional management intervention. A pilot study in California showed that lethal removal of barred owls in combination with habitat conservation may be able to slow or even reverse population declines of spotted owls at local scales, but it remains unknown whether similar results can be obtained in larger areas with different forest conditions and where barred owls are more abundant. In 2015, we implemented a before-after-controlimpact (BACI) experimental design on two study areas in Oregon and Washington with at least 20 years of pre-treatment demographic data on spotted owls to determine if removal of barred owls can improve population trends of spatially associated spotted owls. Here we provide an overview of our research accomplishments and preliminary results in Oregon and Washington in 2015.

Effects of experimental removal of barred owls on population demography of northern spotted owls in Washington and Oregon—2016 progress report

USGS Publications Warehouse

Wiens, J. David; Dugger, Katie M.; Lewicki, Krista E.; Simon, David C.

2017-04-13

Evidence indicates that competition with invasive barred owls (Strix varia) is causing rapid declines in populations of northern spotted owls (S. occidentalis caurina), and that the long-term persistence of spotted owls may be in question without additional management intervention. A pilot study in California showed that removal of barred owls in combination with habitat conservation may be able to slow or even reverse population declines of spotted owls at local scales, but it remains unknown whether similar results can be obtained in areas with different forest conditions and a greater density of barred owls. In 2015, we implemented a before-after-control-impact (BACI) experimental design on three study areas in Oregon and Washington with at least 20 years of pre-treatment demographic data on spotted owls to determine if removal of barred owls can improve localized population trends of spotted owls. Here, we report on research accomplishments and preliminary results from the first 21 months (March 2015–December 2016) of the planned 5-year experiment.

Single underwater image enhancement based on color cast removal and visibility restoration

NASA Astrophysics Data System (ADS)

Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

2016-05-01

Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

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.

Removal of phenol from aqueous solution using polymer inclusion membrane based on mixture of CTA and CA

NASA Astrophysics Data System (ADS)

Benosmane, Nadjib; Boutemeur, Baya; Hamdi, Safouane M.; Hamdi, Maamar

2018-03-01

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. In the present work, the removal of phenol from aqueous solution across polymer inclusion membrane (PIM), based on mixture of cellulose triacetate and cellulose acetate as support (75/25%), calix[4]resorcinarene derivative as a carrier and 2-nitrophenyl octyl ether (2-NPOE) as plasticizer was investigated. The experimental part of this investigation involved the influence of carrier nature, plasticizer concentration, pH phases, and phenol initial concentration on the removal efficiency of phenol from synthetic wastewater. A PIM containing 0.1 g (of mixture polymer), (0.15 g/g mixture of polymer) of carrier and (0.03 ml/g mixture of polymer) of 2-NPOE provided the highest percentage of phenol removal efficiency over a 6-day transport; the removal was found to be about 95%, indeed the removal was found to be highly dependent of pH phases. The feed solution in these transport experiments was at pH 2, while the stripping solution contained 0.20 M NaOH. This study claims that the PIM with a mixture of cellulose derivatives can be used effectively to remove phenols from wastewaters.

Asthma counselling targeted to removal of domestic animals

PubMed Central

Hagan, Louise; Valois, Pierre; Patenaude, Hélène; Boutin, Hélène; Boulet, Louis-Philippe; Lafrenière, France

2008-01-01

OBJECTIVES: To create and evaluate the efficacy of a short individualized educational intervention program, based on Prochaska’s transtheoretical model, for a six-month period in a population of adult asthma patients living with domestic animals but sensitized to these pets. METHODS: A randomized, controlled study using a pretested questionnaire was conducted at three different times (pretest, and at three and six months postintervention). RESULTS: Eleven members (29%) of the intervention group and eight members (21%) of the control group removed their pets within six months (χ2=3.23; P>0.35). The two groups showed similar improvements in their perception of the benefits of pet removal and in their level of belief that they could do it. The experimental group showed a greater improvement in knowledge acquisition about asthma and allergies than the control group (P<0.05). Both experimental and standard educational interventions were effective in facilitating progression through the stages of behavioural change. CONCLUSION: Overall, the results do not support the utility of behavioural change educational intervention, tailored to the transtheoretical model stage of the individual, in the context of convincing patients to remove their pets from their homes. However, the decision-making aid appears to be helpful in raising awareness of the problem of asthma and allergy in the patient, and in developing appropriate knowledge. PMID:18292851

Performance of five plant species in removal of nitrogen and phosphorus from an experimental phytoremediation system in the Ningxia irrigation area.

PubMed

Chen, Chongjuan; Zhao, Tiancheng; Liu, Ruliang; Luo, Liangguo

2017-09-10

Agricultural non-point source (ANPS) pollution is an important contributor to elevated nitrogen (N) and phosphorus (P) in surface waters, which can cause serious environmental problems. Considerable effort has therefore gone into the development of methods that control the ANPS input of N and P to surface waters. Phytoremediation has been extensively used because it is cost-effective, environmentally friendly, and efficient. The N and P loads from agricultural drainage are a potential threat to the water quality of the Yellow River in Ningxia, China. Yet, phytoremediation has only rarely been applied within the Ningxia irrigation area. In an experimental set-up, five species (Ipomoea aquatica, IA; Lactuca sativa, LS; Oryza sativa, OS; Typha latifolia, TL; Zizania latifolia, ZL) were evaluated for their ability to reduce N and P loads over 62 days and five observation periods. Total N and P concentrations, plant biomass, and nutrient content were measured. The results showed that OS, LS, and IA performed better than ZL and TL in terms of nutrients removal, biomass accumulation, and nutrients storage. The highest overall removal rates of N and P (57.7 and 57.3%, respectively) were achieved by LS treatment. In addition, plant uptake contributed significantly to nutrient removal, causing a 25.9-72.0% reduction in N removal and a 54.3-86.5% reduction in P removal. Thus, this study suggests that OS, LS, and IA would be more suitable than ZL and TL for controlling nutrient loads in the Ningxia irrigation area using phytoremediation.

Simultaneous electrodialytic removal of PAH, PCB, TBT and heavy metals from sediments.

PubMed

Pedersen, Kristine B; Lejon, Tore; Jensen, Pernille E; Ottosen, Lisbeth M

2017-08-01

Contaminated sediments are remediated in order to protect human health and the environment, with the additional benefit of using the treated sediments for other activities. Common for many polluted sediments is the contamination with several different pollutants, making remediation challenging with the need of different remedial actions for each pollutant. In this study, electrodialytic remediation (EDR) of sediments was found effective for simultaneous removal of heavy metals and organic pollutants for sediments from Arctic regions - Sisimiut in Greenland and Hammerfest in Norway. The influence of sediment properties and experimental settings on the remediation process was studied by employing multivariate analysis. The importance of the variables studied varied with the pollutant and based on these results it was possible to assess removal processes for the different pollutants. Desorption was found to be important for the removal of heavy metals and TBT, while photolysis was significant for removal of PAH, PCB and TBT. In addition, dechlorination was found to be important for the removal of PCB. The highest removal efficiencies were found for heavy metals, TBT and PCB (>40%) and lower removal efficiencies for PAH (<35%). Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the multiple-ion competition in the adsorption of As(V) onto reclaimed iron-oxide coated sands by fractional factorial design.

PubMed

Hsu, Jia-Chin; Lin, Chien-Jung; Liao, Chih-Hsiang; Chen, Shyi-Tien

2008-07-01

This study describes the competitive effects of selected ions and natural organic matter on As(V) removal using reclaimed iron-oxide coated sands (RIOCS) in the single- and multi-ion systems. A 2(7-3) factional factorial experimental design (FFD) was employed for screening main competitive factors in this adsorption process. As a result, the inhibitive competition effects of the anions on As(V) removal in the single ion system were in the following sequence: PO(4)(3-)>SiO(3)(2-)>HCO(3)(-)>humic acid (HA)>SO(4)(2-)>Cl(-), whereas the cation Ca(2+) was observed to enhance the As(V) removal. In addition, the optimum initial pH for As(V) removal in single-ion system was 5. Based on the estimates of major effects and interactions from the FFD, PO(4)(3-), SiO(3)(2-), Ca(2+) and HA were important factors on As(V) removal in the multi-ion system. The promoters for the As(V) removal were found to be Ca(2+) and, to a lesser extent, SO(4)(2-). The competitive effects of these ions on As(V) removal were in the order of PO(4)(3-), SiO(3)(2-), HA, HCO(3)(-), and Cl(-). In the single ion system, the efficiencies of As(V) removal range from 75% to 96%, much higher than those in the multi-ion system (44%) at the initial pH 5. Clearly, there were some complex anion interactions in the multi-ion system. To promote the removal of As(V) by RIOCS, it is proposed to lower the pH in the single-ion system, while in the multi-ion system, the increase of the Ca(2+) concentration, or decreases of PO(4)(3-), SiO(3)(2-) and HA concentrations is suggested.

Smear Layer Removal in the Apical Third of Root Canals by Two Chelating Agents and Laser: A Comparative in vitro Study

PubMed Central

Ashraf, Hengameh; Asnaashari, Mohammad; Darmiani, Soheila; Birang, Reza

2014-01-01

Introduction: Smear layer (SL) is produced as a result of mechanical instrumentation of the canal(s). Despite the controversies regarding its removal, the evidence-based trend has shifted towards removing and eliminating the SL. Different methods have been used to remove the SL and the aim of this in vitro study was to evaluate the ability of 17% ethylenediaminetetraacetic acid (EDTA), 18% etidronate and Er: YAG on effective removal of the SL. Methods and Materials: Fifty straight single-rooted teeth were divided into three experimental groups (n=15) and one control group of five. The canals were instrumented with HERO 642 rotary files up to 30/0.06. In group 1, canals were irradiated with Er: YAG laser; in groups 2 and 3, canals were irrigated with 17% EDTA and 18% etidronate, respectively. In group 4 (control) distilled water was used for canal irrigation. The amount of remaining SL was quantified according to Hulsmann’s method with scanning electron microscopy (SEM). Data was analyzed by the Kruskal-Wallis and Mann-Whitney U tests (P<0.05). Results: The results showed statistically significant differences in terms of SL removal among the groups (P<0.05). The amount of removed SL by EDTA was significantly greater followed by Er: YAG laser and 18% etidronate. Conclusion: Within the limitations of this study, EDTA was more effective in removing SL compared to Er: YAG and etidronate. PMID:25031596

Is Floral Longevity Influenced by Reproductive Costs and Pollination Success in Cohniella ascendens (Orchidaceae)?

PubMed Central

Abdala-Roberts, Luis; Parra-Tabla, Víctor; Navarro, Jorge

2007-01-01

Background and Aims Although studies have shown that pollen addition and/or removal decreases floral longevity, less attention has been paid to the relationship between reproductive costs and floral longevity. In addition, the influence of reproductive costs on floral longevity responses to pollen addition and/or removal has not yet been evaluated. Here, the orchid Cohniella ascendens is used to answer the following questions. (a) Does experimental removal of flower buds in C. ascendens increase flower longevity? (b) Does pollen addition and/or removal decrease floral longevity, and does this response depend on plant reproductive resource status? Methods To study the effect of reproductive costs on floral longevity 21 plants were selected from which we removed 50 % of the developing flower buds on a marked inflorescence. Another 21 plants were not manipulated (controls). One month later, one of four flowers on each marked inflorescence received one of the following pollen manipulation treatments: control, pollinia removal, pollination without pollinia removal or pollination with pollinia removal. The response variable measured was the number of days each flower remained open (i.e. longevity). Key Results The results showed significant flower bud removal and pollen manipulation effects on floral longevity; the interaction between these two factors was not significant. Flowers on inflorescences with previously removed flower buds remained open significantly longer than flowers on control inflorescences. On the other hand, pollinated flowers closed much faster than control and removed-pollinia flowers, the latter not closing significantly faster than control flowers, although this result was marginal. Conclusions The results emphasize the strong relationship between floral longevity and pollination in orchids, as well as the influence of reproductive costs on the former. PMID:17881335

Efficiency of removal of cadmium from aqueous solutions by plant leaves and the effects of interaction of combinations of leaves on their removal efficiency.

PubMed

Salim, R; Al-Subu, M; Dawod, E

2008-05-01

Removal of cadmium from aqueous solutions using 20 species of plant leaves and combinations of these leaves have been studied. Several factors affecting the removal efficiency have been studied. The most efficient types of plant leaves for the removal of cadmium are those of styrax, plum, pomegranate and walnut. The interaction effect of the combined leaf samples on the efficiency of removal of cadmium has been found to be additive in combinations involving styrax plant leaves but seems to be antagonistic in all other combinations. The optimum experimental conditions for removal of cadmium have been found to be at pH 4.1, using high concentrations of naturally dried plant leaves, using ground leaves and to remove cadmium from agitated aqueous solutions. The percentage of metal removed at an initial cadmium concentration of 10mg/l by the most efficient types of leaves have been found to be 85% for styrax leaves, 85% for plum leaves, 80% for pomegranate leaves, 78% for walnut leaves and 77% for meddler leaves. The presence of foreign ions or complexing agents has been found to reduce the efficiency of removal of cadmium by plant leaves. About 80-85% of the cadmium in charged plant leaves has been released under the influence of changing the pH of the solution, addition of competing ions and the addition of EDTA. The results of removal of cadmium by plant leaves have been found to follow the Freundlich adsorption isotherm, first-order reaction with respect to cadmium and to have intra-pore diffusion as the rate-limiting step.

Ion Exchange Column Tests Supporting Technetium Removal Resin Maturation

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

Nash, C.; McCabe, D.; Hamm, L.

2013-12-20

The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant, currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and sealed in canisters. The LAW glass will be disposed on site. There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the soluble properties of pertechnetate and long half-life ofmore » 99Tc, effective management of 99Tc is important. Options are being explored to immobilize the supplemental LAW portion of the tank waste, as well as to examine the volatility of 99Tc during the vitrification process. Removal of 99Tc, followed by off-site disposal has potential to reduce treatment and disposal costs. A conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal will specifically examine removing 99Tc from the LAW feed stream to supplemental immobilization. SuperLig® 639 is an elutable ion exchange resin. In the tank waste, 99Tc is predominantly found in the tank supernate as pertechnetate (TcO 4 -). Perrhenate (ReO 4 -) has been shown to be a good non-radioactive surrogate for pertechnetate in laboratory testing for this ion exchange resin. This report contains results of experimental ion exchange distribution coefficient and column resin maturation kinetics testing using the resin SuperLig® 639a to selectively remove perrhenate from simulated LAW. This revision includes results from testing to determine effective resin operating temperature range. Loading tests were performed at 45°C, and the computer modeling was updated to include the temperature effects. Equilibrium contact testing indicated that this batch of SuperLig® 639 resin has good performance, with an average perrhenate distribution coefficient of 291 mL/g at a 100:1 phase ratio. This slightly exceeds the computer-modeled equilibrium distribution. The modeling agreed well with the experimental data for perrhenate removal with minor adjustments. Predicted breakthrough performance was on average within about 20% of measured values.« less

Evidence-Based Kernels: Fundamental Units of Behavioral Influence

ERIC Educational Resources Information Center

Embry, Dennis D.; Biglan, Anthony

2008-01-01

This paper describes evidence-based kernels, fundamental units of behavioral influence that appear to underlie effective prevention and treatment for children, adults, and families. A kernel is a behavior-influence procedure shown through experimental analysis to affect a specific behavior and that is indivisible in the sense that removing any of…

Shifts of system performance and microbial community structure in a constructed wetland after exposing silver nanoparticles.

PubMed

Cao, Chong; Huang, Juan; Yan, Chunni; Liu, Jialiang; Hu, Qian; Guan, Wenzhu

2018-05-01

The increasing utilization of silver nanoparticles (Ag NPs) in industry and commerce inevitably raises its release into wastewater. In this work, effects of Ag NPs on system performance and microbial community along the way of a vertical flow constructed wetland (VFCW) were investigated, along with the removal and fate of Ag NPs within the system. Results showed that the performance of control wetland kept stable during the experimental period, and the top substrate layer (soil layer) of wetland could remove most of pollutants in the influent. The study also suggested that addition of Ag NPs did not significantly affect organic matters removal. However, adverse effects were observed on the nitrogen and phosphorus removal. Removal efficiencies of TN, NH 4 + -N and TP approximately obviously reduced by approximately 10.10%, 8.42% and 28.35% respectively in contrast to before dosing after exposing 100 μg/L Ag NPs for 94 d, while the no dosing wetland with the stable performance. It was found that Ag NPs accumulated in the upper soil layer more than in the lower soil layer, and Ag NPs could enter into the plant tissues. After continuous input of Ag NPs, removal efficiency of Ag NPs was measured as 95.72%, which showed that the CW could effectively remove Ag NPs from the wastewater. The high-throughput sequencing results revealed that Ag NPs caused the shifts in microbial community structures and changed the relative abundances of key functional bacteria, which finally resulted in a lower efficiency of biological nitrogen and phosphorus removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Density Driven Removal of Sediment from a Buoyant Muddy Plume

NASA Astrophysics Data System (ADS)

Rouhnia, M.; Strom, K.

2014-12-01

Experiments were conducted to study the effect of settling driven instabilities on sediment removal from hypopycnal plumes. Traditional approaches scale removal rates with particle settling velocity however, it has been suggested that the removal from buoyant suspensions happens at higher rates. The enhancement of removal is likely due to gravitational instabilities, such as fingering, at two-fluid interface. Previous studies have all sought to suppress flocculation, and no simple model exists to predict the removal rates under the effect of such instabilities. This study examines whether or not flocculation hampers instability formation and presents a simple removal rate model accounting for gravitational instabilities. A buoyant suspension of flocculated Kaolinite overlying a base of clear saltwater was investigated in a laboratory tank. Concentration was continuously measured in both layers with a pair of OBS sensors, and interface was monitored with digital cameras. Snapshots from the video were used to measure finger velocity. Samples of flocculated particles at the interface were extracted to retrieve floc size data using a floc camera. Flocculation did not stop creation of settling-driven fingers. A simple cylinder-based force balance model was capable of predicting finger velocity. Analogy of fingering process of fine grained suspensions to thermal plume formation and the concept of Grashof number enabled us to model finger spacing as a function of initial concentration. Finally, from geometry, the effective cross-sectional area was correlated to finger spacing. Reformulating the outward flux expression was done by substitution of finger velocity, rather than particle settling velocity, and finger area instead of total area. A box model along with the proposed outward flux was used to predict the SSC in buoyant layer. The model quantifies removal flux based on the initial SSC and is in good agreement with the experimental data.

Landfill leachate treatment by an experimental subsurface flow constructed wetland in tropical climate countries.

PubMed

Ujang, Z; Soedjono, E; Salim, M R; Shutes, R B

2005-01-01

Municipal leachate was treated in an experimental unit of constructed wetlands of subsurface flow type. The parameters studied were organics (BOD and COD), solids and heavy metals (Zn, Ni, Cu, Cr and Pb). Using two types of emergent plants of Scirpus globulosus and Eriocaulon sexangulare, more than 80% removal was achieved for all the parameters. E. sexangulare removed organics and heavy metals better than Scirpus globulosus. A higher concentration of heavy metals in the influent did not change the removal efficiency.

Assessing the efficacy of citrus aurantifolia extract on smear layer removal with scanning electron microscope.

PubMed

Bolhari, Behnam; Sharifian, Mohammad Reza; Aminsobhani, Mohsen; Monsef Esfehani, Hamid Reza; Tavakolian, Pardis

2012-01-01

The purpose of this study was to determine the effects of citrus aurantifolia (CA) extract on smear layer removal in different parts of root canals. Thirty-nine single-rooted human teeth were randomly divided into three experimental (n=12) and one control (n=3) groups. Teeth were instrumented using MTwo rotary instruments. Root canals were irrigated with NaOCl during instrumentation. The canals in each group were irrigated with one of the following: completed mixture of citrus aurantifolia extracts, 17% EDTA, and alcoholic extract of CA. Distilled water was used for the control group. The irrigants were left within the canal for 20 minutes, and then rinsed with normal saline solution. Teeth were subsequently split longitudinally into 2 halves, and the canals were examined by a scanning electron-microscope. Cleanliness was evaluated using a five point scoring system. Statistical significant difference was found between groups (P<0.05). The smear layer was more effectively removed with 17% EDTA compared to alcoholic CA extract. However, they were both able to remove the smear layer in the coronal segment. Completed CA extract removed more smear layer in coronal and middle parts compared with the alcoholic extract (P=0.001); however, there was no significant difference in the apical part. Both of the alcoholic and completed mixtures of citrus aurantifolia extracts were not able to effectively remove smear layer compared with 17% EDTA during root canal therapy.

Effect of garlic solution to Bacillus sp. removal

NASA Astrophysics Data System (ADS)

Zainol, N.; Rahim, S. R.

2018-04-01

Biofilm is a microbial derived sessile community characterized by cells that are irreversibly attached to a substratum or interface to each other, embedded in a matrix of extracellular polymeric substances that they have produced. Bacillus sp. was used as biofilm model in this study. The purpose of this study is to determine the effect of Garlic solution in term of ratio of water and Garlic solution (W/G) and ratio of Garlic solution to Bacillus sp. (GS/B) on Bacillus sp removal. Garlic solution was used to remove Bacillus sp. In this study, Garlic solution was prepared by crushing the garlic and mixed it with water. the Garlic solution was added into Bacillus sp. mixture and mixed well. The mixture then was spread on nutrient agar. The Bacillus sp. weight on agar plate was measured by using dry weight measurement method. In this study, initially Garlic solution volume and Garlic solution concentration were studied using one factor at time (OFAT). Later two-level-factorial analysis was done to determine the most contributing factor in Bacillus sp. removal. Design Expert software (Version 7) was used to construct experimental table where all the factors were randomized. Bacilus sp removal was ranging between 42.13% to 99.6%. The analysis of the results showed that at W/G of 1:1, Bacillus sp. removal increased when more Garlic solution was added to Bacillus sp. Effect of Garlic solution to Bacillus sp. will be understood which in turn may be beneficial for the industrial purpose.

The effect of oxidant addition on ferrous iron removal from multi-element acidic sulphate solutions

NASA Astrophysics Data System (ADS)

Mbedzi, Ndishavhelafhi; Ibana, Don; Dyer, Laurence; Browner, Richard

2017-01-01

This study was an investigation on the hydrolytic precipitation of iron from simulated pregnant leach solution (PLS) of nickel laterite atmospheric leaching. The effect of equilibrium pH, temperature and the addition of oxidant on total iron (ferrous (Fe (II)) and ferric (Fe (III)), aluminium and chromium removal was investigated together with the associated nickel and cobalt losses to the precipitate. Systematic variations of the experimental variables revealed ≥99% of the ferric iron can be removed from solution at conditions similar to those used in standard partial neutralisation in zinc and nickel production, pH of 2.5 and temperature less than 100 °C with minimal losses (<0.5%) of both nickel and cobalt. Temperature variation from 55 to 90 °C had no significant effect on the magnitude of Fe (III) precipitation but led to a significant increase in aluminium removal from 67% to 95% and improved the filterability of the precipitates. There was no ferrous iron precipitation even at a pH of 3.75 in the absence of an oxidant with its removal (98%) achieved by oxidative precipitation with oxygen gas at pH 3.5. Unlike Fe (III) precipitation, the operating temperature significantly affects oxidative precipitation of Fe (II). Hence, in practical application, the hydrolytic precipitation and oxidation to remove iron must be operated at 85 °C to ensure both ferrous and ferric iron are precipitated.

Carbofuran removal in continuous-photocatalytic reactor: Reactor optimization, rate-constant determination and carbofuran degradation pathway analysis.

PubMed

Vishnuganth, M A; Remya, Neelancherry; Kumar, Mathava; Selvaraju, N

2017-05-04

Carbofuran (CBF) removal in a continuous-flow photocatalytic reactor with granular activated carbon supported titanium dioxide (GAC-TiO 2 ) catalyst was investigated. The effects of feed flow rate, TiO 2 concentration and addition of supplementary oxidants on CBF removal were investigated. The central composite design (CCD) was used to design the experiments and to estimate the effects of feed flow rate and TiO 2 concentration on CBF removal. The outcome of CCD experiments demonstrated that reactor performance was influenced mainly by feed flow rate compared to TiO 2 concentration. A second-order polynomial model developed based on CCD experiments fitted the experimental data with good correlation (R 2 ∼ 0.964). The addition of 1 mL min -1 hydrogen peroxide has shown complete CBF degradation and 76% chemical oxygen demand removal under the following operating conditions of CBF ∼50 mg L -1 , TiO 2 ∼5 mg L -1 and feed flow rate ∼82.5 mL min -1 . Rate constant of the photodegradation process was also calculated by applying the kinetic data in pseudo-first-order kinetics. Four major degradation intermediates of CBF were identified using GC-MS analysis. As a whole, the reactor system and GAC-TiO 2 catalyst used could be constructive in cost-effective CBF removal with no impact to receiving environment through getaway of photocatalyst.

Inhibition of boric acid and sodium borate on the biological activity of microorganisms in an aerobic biofilter.

PubMed

Güneş, Y

2013-01-01

The aim of this work was to study the inhibition effect of boric acid and sodium borate on the treatment of boron containing synthetic wastewater by a down flow aerobic fixed bed biofilm reactor at various chemical oxygen demand (COD)/boron ratios (0.47-20.54). The inhibitory effect of boron on activated sludge was evaluated on the basis of COD removal during the experimental period. The biofilter (effective volume = 2.5 L) was filled with a ring of plastic material inoculated with acclimated activated sludge. The synthetic wastewater composed of glucose, urea, KH2PO4, MgSO4, Fe2 SO4, ZnSO4 x 7H20, KCl, CaCl2, and di-sodium tetraborate decahydrate or boric acid (B = 100-2000 mg L(-1)). The biological treatment of boron containing wastewater resulted in a low treatment removal rate due to the reduced microbial activity as a result of toxic effects of high boron concentrations. The decrease in the COD removal rate by the presence of either boric acid or sodium borate was practically indistinguishable. It was observed from the experiments that about 90-95% of COD removal was possible at high COD/boron ratios.

Effects of removal of different chemical components on moisture sorption property of Populus euramericana Cv. under dynamic hygrothermal conditions

NASA Astrophysics Data System (ADS)

Yang, Tiantian; Zhou, Haizhen; Ma, Erni; Wang, Jiamin

2018-09-01

Effects of chemical components on wood sorption property under dynamic condition were investigated for the first time. Hemicellulose, lignin and extractive (denoted as DHC, DL and DE, respectively) were removed from Populus euramericana Cv., 20 mm in radial (R) and tangential (T) directions with thickness of 4 mm along the grain, then the wood was subjected to cyclic tests where relative humidity (RH) varied from 45% to 75% sinusoidally at 25 °C. Based on measured data automatically, the results showed that, various chemical components had different effects on dynamic sorption behaviors of wood. The DL exhibited the largest moisture content and diffusion coefficient, followed by the DE, Control and DHC. This indicated lignin or extractive removal accelerated the dynamic sorption process and improved hygroscopicity of wood, while hemicellulose removal caused opposite effects. Theoretical sorption model was further applied and the modeled curves fitted satisfactorily with experimental data. Dynamic moisture gradient distribution inside the different treated wood was investigated and amplitude of moisture showed negative relation with wood element depth, while phase lag presented an opposite trend. Amplitude of DL was the largest while its phase lag was the least. Conditioning thickness for RH was greatest for DHC, about twice as much as the minimum of DL.

DETECTORS AND EXPERIMENTAL METHODS: Heuristic approach for peak regions estimation in gamma-ray spectra measured by a NaI detector

NASA Astrophysics Data System (ADS)

Zhu, Meng-Hua; Liu, Liang-Gang; You, Zhong; Xu, Ao-Ao

2009-03-01

In this paper, a heuristic approach based on Slavic's peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.

[Microcystin safety study during Cyanobacteria removal by pressure enhanced coagulation process].

PubMed

Jiang, Xin-Yue; Luan, Qing; Cong, Hai-Bing; Xu, Si-Tao; Liu, Yu-Jiao; Zhu, Xue-Yuan

2014-11-01

Pressure enhanced coagulation and sedimentation technique is an effective way for blue algae treatment. It is not clear whether Cyanobacteria balloon rupture will cause Cyanobacteria cells rupture, resulting in high intracellular concentrations of microcystin LR leak into the water, affecting drinking water safety. Therefore, in this study experimental comparative study of pressure and pre-oxidation of water containing Cyanobacteria was carried out to examine the microcystin LR concentration changes and Cyanobacteria removal efficiency. The results showed that microcystin concentration increase was not significant by the pre-treatment with Cyanobacteria water pressure, while the pre-oxidation process caused a significant increase in the concentration of microcystin. After 0.5-0.8 MPa pressure coagulation and sedimentation, removal of Cyanobacteria basically was over 90%, up to 93.5%, while the removal rate by pre-oxidation was low and unstable. Effluent turbidity is also significantly better in the pre-pressure method than the pre-oxidation. The results indicated that pressure enhanced coagulation is a safe and reliable method for Cyanobacteria removal.

Optimization of Photooxidative Removal of Phenazopyridine from Water

NASA Astrophysics Data System (ADS)

Saeid, Soudabeh; Behnajady, Mohammad A.; Tolvanen, Pasi; Salmi, Tapio

2018-05-01

The photooxidative removal of analgesic pharmaceutical compound phenazopyridine (PhP) from aqueous solutions by UV/H2O2 system with a re-circulated photoreactor was investigated. Response surface methodology (RSM) was employed to optimize the effect of operational parameters on the photooxidative removal efficiency. The investigated variables were: the initial PhP and H2O2 concentrations, irradiation time, volume of solution and pH. The analysis of variance (ANOVA) of quadratic model demonstrated that the described model was highly significant. The predicted values of the photooxidative removal efficiency were found to be in a fair agreement with experimental values ( R 2 = 0.9832, adjusted R 2 = 0.9716). The model predicted that the optimal reaction conditions for a maximum removal of PhP (>98%) were: initial PhP concentration less than 23 mg L-1, initial concentration of H2O2 higher than 470 mg L-1, solution volume less than 500 mL, pH close to 2 and irradiation time longer than 6 min.

Adsorption kinetics, isotherms and thermodynamics of atrazine removal using a banana peel based sorbent.

PubMed

Chaparadza, Allen; Hossenlopp, Jeanne M

2012-01-01

Atrazine removal from water by treated banana peels was studied. The effect of pH, contact time, initial atrazine concentration, and temperature were investigated. Batch experiments demonstrated that 15 g L(-1) adsorbent dosage removed 90-99% of atrazine from 1-150 ppm aqueous solutions. The removal was both pH and temperature dependent with the most atrazine removed between pH 7 and 8.2 and increased with increasing temperature. Equilibrium data fitted well to the Langmuir and Redlich-Peterson models in the concentration and temperature ranges investigated, with a maximum adsorption capacity of 14 mg g(-1). Simple mass transfer models were applied to the experimental data to examine the adsorption mechanism and it was found that both external mass transfer and intraparticle diffusion played important roles in the adsorption mechanisms. The enthalpy of atrazine adsorption was evaluated to be 67.8 ± 6.3 kJ mol(-l) with a Gibbs free energy of -5.7 ± 1.2 kJ mol(-1).

Nitrogen Removal Characteristics of Pseudomonas putida Y-9 Capable of Heterotrophic Nitrification and Aerobic Denitrification at Low Temperature

PubMed Central

He, Tengxia; Ye, Qing; Chen, Yanli; Xie, Enyu; Zhang, Xue

2017-01-01

The cold-adapted bacterium Pseudomonas putida Y-9 was investigated and exhibited excellent capability for nitrogen removal at 15°C. The strain capable of heterotrophic nitrification and aerobic denitrification could efficiently remove ammonium, nitrate, and nitrite at an average removal rate of 2.85 mg, 1.60 mg, and 1.83 mg NL−1 h−1, respectively. Strain Y-9 performed nitrification in preference to denitrification when ammonium and nitrate or ammonium and nitrite coexisted in the solution. Meantime, the presence of nitrate had no effect on the ammonium removal rate of strain Y-9, and yet the presence of high concentration of nitrite would inhibit the cell growth and decrease the nitrification rate. The experimental results indicate that P. putida Y-9 has potential application for the treatment of wastewater containing high concentrations of ammonium along with its oxidation products at low temperature. PMID:28293626

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.

Study on The Application of Composed TiO2-diatomite in The Removal of Phenol in Water

NASA Astrophysics Data System (ADS)

Liu, S.; Li, J.

2017-10-01

As an environmentally friendly pollution control technology, TiO2 photocatalytic technology has a broad prospect in the field of environmental protection. In this paper, composed nano-TiO2-diatomite were prepared by depositing TiO2 nanoparticles on the surface of diatomite microparticles. The nano-TiO2/diatomite composed photocatalyst is used to remove phenol in water in a specific designed reaction box under 4 different operation factors such as different reaction time, different pollutant concentration, different UV light powers and different amount of catalytic powder. The experimental results indicate that the phenol removal percentages are influenced by the reaction time most significantly, the second is the phenol concentration, the next one is the photocatalyst amount and the UV light powers’ effect is quite limited. Tthe degradation of phenol typically slows down at the reaction time about 30 or 60 minutes. Besides that, the phenol removal kinetic removal rates were also investigated.

Perfluorocarbon perfused vitrectomy: animal studies.

PubMed

Quiroz-Mercado, Hugo; Suarez-Tatá, Luis; Magdalenic, Rudi; Murillo-López, Sergio; García-Aguirre, Gerardo; Guerrero-Naranjo, Jose; Rodríguez-Reyes, Abelardo A

2004-02-01

To investigate the feasibility and advantages of using perfluorocarbon liquid (PCL) perfusion to remove vitreous during suction-cutting vitrectomy in rabbit and pig eyes. Experimental study. Balanced salt solution (BSS) was replaced by PCL perfusion during experimental vitrectomy. Oxygenated or nonoxygenated PCL was used in a recycling or a nonrecycling system. Recycling was achieved by two systems: a manual recycling system or a closed-loop system. The experiments in this study consisted of: an in vitro solubility observation, safety and feasibility of vitrectomy in rabbit eyes, effectiveness of vitrectomy with equal vitrectomy time in rabbit eyes, and retinal stability and pigment and blood dispersion in porcine eyes. Toxicity was assessed by a complete ophthalmic examination, endothelial cell count, electroretinography, and histopathology. Vitreous, blood, and pigments were immiscible in PCL. Manual recycling required less amounts of PCL than nonrecycling (15 vs 25 cc). Oxygenated and nonoxygenated PCL were not toxic. Perfluorocarbon liquid infusion removed more vitreous than balanced salt solution in a 3-minute vitrectomy time using the same settings on the vitrectomy machine. The PCL infusion in porcine eyes stabilized the retina and isolated vitreous cavity from pigment and blood and maintained a clear vitreous cavity. These data indicate that perfusion of PCL can be used to remove vitreous with a suction-cutting probe in rabbit and pig eyes. Retinal stability and isolation of the vitreous cavity at the time of vitreous removal along with PCL immiscibility and its specific gravity suggest that PCL has a potential clinical use as an irrigating solution to remove vitreous.

Automatic control and remote monitoring system for biological nutrient removal on small wastewater treatment plants in Korea.

PubMed

Lee, H; Min, Y M; Park, C H; Park, Y H

2004-01-01

Many small-size wastewater treatment plants in Korea's rural communities are designed to remove organic and suspended matter only, and they generally show a large fluctuation in the influent loading compared to municipal wastewater treatment plants (MWWTPs). They also have no professional engineers stationed for efficient operation against mechanical breakdown. For those reasons, the wastewater treatment plants have low efficiency in treatment of nitrogen and phosphorus as well as organic matter. In order to solve those problems, this study developed an automatic control system and RMS (remote monitoring system), which can keep efficiency stable despite any change in the small plants' loading rates and are capable of removing nutrient materials such as nitrogen or phosphorus. According to the results of the Experimental SBR system of the automatic control program, complete nitrification was made under oxic conditions and denitrification occurred as NO3-N concentration decreased by 0.5 mg/l in anoxic conditions and excellent nitrogen removal efficiency was seen generally. The Experimental SBR system created "phosphate release and uptake" effectively and displayed phosphate-removing efficiency up to more than 80% as the concentration of effluent was kept low by 0.4 mg/l. RMS developed in this study transmits a plant's data and operation states to clients in remote locations in real-time interval through the Internet. Therefore, although you are in a remote location, it allows you to see if a plant is properly operated or there is any breakdown.

Removal of methylene blue from aqueous solution by wood millet carbon optimization using response surface methodology

NASA Astrophysics Data System (ADS)

Ghaedi, Mehrorang; Kokhdan, Syamak Nasiri

2015-02-01

The use of cheep, non-toxic, safe and easily available adsorbent are efficient and recommended material and alternative to the current expensive substance for pollutant removal from wastewater. The activated carbon prepared from wood waste of local tree (millet) extensively was applied for quantitative removal of methylene blue (MB), while simply. It was used to re-used after heating and washing with alkaline solution of ethanol. This new adsorbent was characterized by using BET surface area measurement, FT-IR, pH determination at zero point of charge (pHZPC) and Boehm titration method. Response surface methodology (RSM) by at least the number of experiments main and interaction of experimental conditions such as pH of solution, contact time, initial dye concentration and adsorbent dosage was optimized and set as pH 7, contact time 18 min, initial dye concentration 20 ppm and 0.2 g of adsorbent. It was found that variable such as pH and amount of adsorbent as solely or combination effects seriously affect the removal percentage. The fitting experimental data with conventional models reveal the applicability of isotherm models Langmuir model for their well presentation and description and Kinetic real rate of adsorption at most conditions efficiently can be represented pseudo-second order, and intra-particle diffusion. It novel material is good candidate for removal of huge amount of MB (20 ppm) in short time (18 min) by consumption of small amount (0.2 g).

Experimental design and modeling of ultrasound assisted simultaneous adsorption of cationic dyes onto ZnS: Mn-NPs-AC from binary mixture.

PubMed

Asfaram, Arash; Ghaedi, Mehrorang; Yousefi, Fakhri; Dastkhoon, Mehdi

2016-11-01

The manganese impregnated zinc sulfide nanoparticles deposited on activated carbon (ZnS: Mn-NPs-AC) which fully was synthesized and characterized successfully applied for simultaneous removal of malachite green and methylene blue in binary situation. The effects of variables such as pH (2.0-10.0), sonication time (1-5min), adsorbent mass (0.005-0.025g) and MB and MG concentration (4-20mgL(-1)) on their removal efficiency was studied dy central composite design (CCD) to correlate dyes removal percentage to above mention variables that guides amongst the maximum influence was seen by changing the sonication time and adsorbent mass. Sonication time, adsorbent mass and pH in despite of dyes concentrations has positive relation with removal percentage. Multiple regression analysis of the experimental results is associated with 3-D response surface and contour plots that guide setting condition at pH of 7.0, 3min sonication time, 0.025g Mn: ZnS-NPs-AC and 15mgL(-1) of MB and MG lead to achievement of removal efficiencies of 99.87% and 98.56% for MG and MB, respectively. The pseudo-second-order model as best choice efficiency describe the dyes adsorption behavior, while MG and MB maximum adsorption capacity according to Langmuir was 202.43 and 191.57mgg(-1). Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced degradation of paracetamol by UV-C supported photo-Fenton process over Fenton oxidation.

PubMed

Manu, B; Mahamood, S

2011-01-01

For the treatment of paracetamol in water, the UV-C Fenton oxidation process and classic Fenton oxidation have been found to be the most effective. Paracetamol reduction and chemical oxygen demand (COD) removal are measured as the objective functions to be maximized. The experimental conditions of the degradation of paracetamol are optimized by the Fenton process. Influent pH 3, initial H(2)O(2) dosage 60 mg/L, [H(2)O(2)]/[Fe(2+)] ratio 60 : 1 are the optimum conditions observed for 20 mg/L initial paracetamol concentration. At the optimum conditions, for 20 mg/L of initial paracetamol concentration, 82% paracetamol reduction and 68% COD removal by Fenton oxidation, and 91% paracetamol reduction and 82% COD removal by UV-C Fenton process are observed in a 120 min reaction time. By HPLC analysis, 100% removal of paracetamol is observed at the above optimum conditions for the Fenton process in 240 min and for the UV-C photo-Fenton process in 120 min. The methods are effective and they may be used in the paracetamol industry.

Use of laterite for the removal of fluoride from contaminated drinking water.

PubMed

Sarkar, Mitali; Banerjee, Aparna; Pramanick, Partha Pratim; Sarkar, Asit R

2006-10-15

The effects of different operational variables on the mechanistic function of laterite in removal of fluoride have been investigated. Thermodynamic parameters such as free energy change, enthalpy, and entropy of the process, as well as the sorption isotherm, were evaluated. The extent of solute removal is determined by initial solute concentration, operational conditions, laterite dose, and solution pH. For a fixed set of experimental conditions, a model equation is developed from which the percent removal corresponding to each load of fluoride is determined. The mechanism of fluoride adsorption is governed by the zero point charge of laterite and follows a first-order rate equation. pH has a vital role influencing the surface characteristics of laterite. To simulate the flow dynamics, fluoride solution was run through a fixed bed column. The pattern of breakthrough curves for different influent fluoride concentration, pH, and column bed height was characterized. The column efficiency was tested from the bed depth-service time model. The elution of the retained fluoride was studied and the effectiveness of column operation was determined by the retention-elution cycles.

Treatment of industrial estate wastewater by the application of electrocoagulation process using iron electrodes.

PubMed

Yavuz, Y; Ögütveren, Ü B

2018-02-01

In this study electrocoagulation (EC) of industrial estate wastewater taken from the inlet of wastewater treatment plant was investigated using sacrificial iron electrodes. Employing a pole changer to homogenous consumption of electrodes, studies on the parameters such as current density, supporting electrolyte concentration and initial pH, which have significant effects on COD removal and hence the energy consumption, were performed. Hydrogen peroxide was used in different concentrations to observe its effects on COD removal efficiency and the energy consumption. Sludge productions were also calculated for all experiments. COD removal efficiency of ∼92% was obtained at the best experimental conditions (i = 30 mA/cm 2 , SE = 3 mM Na 2 SO 4 , pH = original pH (∼6) of the wastewater, 1500 mg/L H 2 O 2 ) with an energy cost of €3.41/m 3 wastewater treated and the sludge production of 5.45 g per g COD removed. Copyright © 2017 Elsevier Ltd. All rights reserved.

EEOC claims employer refused reasonable accommodation. Equal Employment Opportunity Commission.

PubMed

1995-06-30

The Equal Employment Opportunity Commission (EEOC) has sued Spectacor, one of the largest stadium-management companies, on behalf of employee [name removed]. [Name removed], who claimed his employer refused to grant him flexible work hours to accommodate his AIDS diagnosis. [Name removed] had submitted a note from one of his doctors stating that [name removed] had AIDS and was taking an experimental medicine. The doctors requested some added flexibility in working hours to enable [name removed] to prepare special meals and take showers to reduce the discomfort of the experimental medicines he was taking. Spectacor, instead of granting the request, informed [name removed] that his job was in jeopardy and that he would be discharged because of absenteeism and declining productivity. The suit alleges Spectacor violated the Americans with Disabilities Act (ADA) by refusing to grant [name removed] a reasonable accommodation for his disability and that the employer had breached its obligation to keep confidential his medical information. Spectacor denied that its refusal to accommodate [name removed]'s scheduling requests constituted a violation of the ADA.

Influence of Removal of a Non-native Tree Species Mimosa caesalpiniifolia Benth. on the Regenerating Plant Communities in a Tropical Semideciduous Forest Under Restoration in Brazil.

PubMed

Podadera, Diego S; Engel, Vera L; Parrotta, John A; Machado, Deivid L; Sato, Luciane M; Durigan, Giselda

2015-11-01

Exotic species are used to trigger facilitation in restoration plantings, but this positive effect may not be permanent and these species may have negative effects later on. Since such species can provide a marketable product (firewood), their harvest may represent an advantageous strategy to achieve both ecological and economic benefits. In this study, we looked at the effect of removal of a non-native tree species (Mimosa caesalpiniifolia) on the understory of a semideciduous forest undergoing restoration. We assessed two 14-year-old plantation systems (modified "taungya" agroforestry system; and mixed plantation using commercial timber and firewood tree species) established at two sites with contrasting soil properties in São Paulo state, Brazil. The experimental design included randomized blocks with split plots. The natural regeneration of woody species (height ≥0.2 m) was compared between managed (all M. caesalpiniifolia trees removed) and unmanaged plots during the first year after the intervention. The removal of M. caesalpiniifolia increased species diversity but decreased stand basal area. Nevertheless, the basal area loss was recovered after 1 year. The management treatment affected tree species regeneration differently between species groups. The results of this study suggest that removal of M. caesalpiniifolia benefited the understory and possibly accelerated the succession process. Further monitoring studies are needed to evaluate the longer term effects on stand structure and composition. The lack of negative effects of tree removal on the natural regeneration indicates that such interventions can be recommended, especially considering the expectations of economic revenues from tree harvesting in restoration plantings.

Influence of Removal of a Non-native Tree Species Mimosa caesalpiniifolia Benth. on the Regenerating Plant Communities in a Tropical Semideciduous Forest Under Restoration in Brazil

NASA Astrophysics Data System (ADS)

Podadera, Diego S.; Engel, Vera L.; Parrotta, John A.; Machado, Deivid L.; Sato, Luciane M.; Durigan, Giselda

2015-11-01

Exotic species are used to trigger facilitation in restoration plantings, but this positive effect may not be permanent and these species may have negative effects later on. Since such species can provide a marketable product (firewood), their harvest may represent an advantageous strategy to achieve both ecological and economic benefits. In this study, we looked at the effect of removal of a non-native tree species ( Mimosa caesalpiniifolia) on the understory of a semideciduous forest undergoing restoration. We assessed two 14-year-old plantation systems (modified "taungya" agroforestry system; and mixed plantation using commercial timber and firewood tree species) established at two sites with contrasting soil properties in São Paulo state, Brazil. The experimental design included randomized blocks with split plots. The natural regeneration of woody species (height ≥0.2 m) was compared between managed (all M. caesalpiniifolia trees removed) and unmanaged plots during the first year after the intervention. The removal of M. caesalpiniifolia increased species diversity but decreased stand basal area. Nevertheless, the basal area loss was recovered after 1 year. The management treatment affected tree species regeneration differently between species groups. The results of this study suggest that removal of M. caesalpiniifolia benefited the understory and possibly accelerated the succession process. Further monitoring studies are needed to evaluate the longer term effects on stand structure and composition. The lack of negative effects of tree removal on the natural regeneration indicates that such interventions can be recommended, especially considering the expectations of economic revenues from tree harvesting in restoration plantings.

Frictional forces in material removal for glasses and ceramics using magnetorheological finishing

NASA Astrophysics Data System (ADS)

Miao, Chunlin

Magnetorheological finishing (MRF) spotting experiments on stationary parts are conducted in this work to understand the material removal mechanism in MRF. Drag force and normal force are measured in situ, simultaneously for the first time for a variety of optical materials in MRF. We study material removal process in MRF as a function of material mechanical properties. We experimentally demonstrate that material removal in MRF is strongly related to shear stress. Shear stress is predominantly determined by material mechanical properties. A modified Preston's equation is proposed to estimate the material removal in MRF by combining shear stress and material mechanical properties. We investigate extensively the effect of various MRF process parameters, including abrasive concentration, magnetic field strength, penetration depth and wheel speed, on material removal efficiency. Material removal rate model is expanded to include these parameters. We develop a nonaqueous magnetorheological (MR) fluid for examining the mechanical contribution in MRF material removal. This fluid is based on a combination of two CI particles and a combination of two organic liquids. Material removal with this nonaqueous MR fluid is discussed. We formulate a new corrosion resistant MR fluid which is based on metal oxide coated carbonyl iron (CI) particles. The rheological behavior, stability and corrosion resistance are examined.

Fast start-up of the CANON process with a SABF and the effects of pH and temperature on nitrogen removal and microbial activity.

PubMed

Yue, Xiu; Yu, Guangping; Liu, Zhuhan; Tang, Jiali; Liu, Jian

2018-04-01

The long start-up time of the completely autotrophic nitrogen removal over nitrite (CANON) process is one of the main disadvantages of this system. In this paper, the CANON process with a submerged aerated biological filter (SABF) was rapidly started up within 26 days. It gave an average ammonium nitrogen removal rate (ANR) and a total nitrogen removal rate (TNR) of 94.2% and 81.3%, respectively. The phyla Proteobacteria and Planctomycetes were confirmed as the ammonia oxidizing bacteria (AOB) and anaerobic ammonium oxidation bacteria (AnAOB). The genus Candidatus Brocadia was the major contributor of nitrogen removal. pH and temperature affect the performance of the CANON process. This experimental results showed that the optimum pH and temperature were 8.0 and 30 °C, respectively, which gave the highest average ANR and TNR values of 94.6% and 85.1%, respectively. This research could promote the nitrogen removal ability of CANON process in the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative evaluation of cyanide removal by adsorption, biodegradation, and simultaneous adsorption and biodegradation (SAB) process using Bacillus cereus and almond shell.

PubMed

Dwivedi, Naveen; Balomajumder, Chandrajit; Mondal, Prasenji

2016-07-01

The present study aimed to investigate the removal efficiency of cyanide from contaminated water by adsorption, biodegradation and simultaneous adsorption and biodegradation (SAB) process individually in a batch reactor. Adsorption was achieved by using almond shell granules and biodegradation was conducted with suspended cultures of Bacillus cereus, whereas SAB process was carried out using Bacillus cereus and almond shell in a batch reactor. The effect of agitation time, pH, and initial cyanide concentration on the % removal of cyanide has been discussed. Under experimental conditions, optimum removal was obtained at pH 7 with agitation time of 48 hrs and temperature of 35 degrees C. Cyanide was utilized by bacteria as sole source of nitrogen for growth. The removal efficiencies of cyanide by adsorption, biodegradation, and SAB were found to be 91.38%, 95.87%, and 99.63%, respectively, at initial cyanide concentration of 100 mg l(-1). The removal efficiency of SAB was found to be better as compared to that of biodegradation and adsorption alone.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-06-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

Application of Colloidal Filtration Theory on Textile Fibrous Media: Effect of Fiber Orientation on Bacterial Removal Efficiency and Attachment

NASA Astrophysics Data System (ADS)

Roy, Sukumar; Ghosh, Subrata; Bhowmick, Niranjan

2018-05-01

A mechanism to remove the Pseudomonas bacteria from contaminated water by using textile fibrous media has been proposed in this article. The attachment of Pseudomonas bacteria on nylon fibrous media was studied in laboratory column experiment. A systematic study was carried out to investigate the attachment of bacteria on the fibrous material as a function of fiber orientation to the direction of the liquid flow. Three types of textiles media with different orientation fiber were selected for the experiment (i.e. 0°, 45° and 90°). It was found that the bacteria removal efficiency was comparatively higher at 90° orientation as compared to that of 45° and 0° orientation of fibrous media, suggesting that the removal efficiency of bacteria (1 - Fp) was depended on fiber orientation. The removal trends were explained on the basis of colloidal filtration theory. This is due to the higher single collector contact efficiency and attachment/collision efficiency as observed from the experimental data of removal efficiency.

Selective removal of mercury from aqueous solutions using thiolated cross-linked polyethylenimine

NASA Astrophysics Data System (ADS)

Saad, Dalia M.; Cukrowska, Ewa M.; Tutu, Hlanganani

2013-06-01

A successful approach to develop an insoluble form of polyethylenimine with a thiol-based functional group for selective removal of Hg(II) from aqueous solutions is reported. The selectivity of the modified polymer for Hg(II) as well as its ability to be regenerated for re-use has been studied. The synthesised polymer exhibited high selectivity for Hg(II) with high removal efficiency of up to 97 %, even in the presence of competing ions. The Freundlich isotherm was found to best fit and describe the experimental data. The pseudo-second-order equation explains the adsorption kinetics most effectively implying chemisorption. The thermodynamic study of the adsorption process revealed high activation energies >41 kJ mol-1, further confirming chemisorption as the mechanism of interaction between mercury ions and the polymer surface. The polymer exhibited good potential for re-use after many cycles of regeneration, giving good removal efficiency up to the fifth cycle.

Continuous electrochemical oxidation of methyl orange waste water using a three-dimensional electrode reactor.

PubMed

Liu, Zhigang; Wang, Feifei; Li, Yansheng; Xu, Tianlong; Zhu, Shaomin

2011-06-01

The removal of methyl orange wastewater was experimentally investigated using a three-dimensional electrode reactor with granular activated carbon and titanium filter electrodes arrays. The effects of the electric current, the residence time and the initial dye concentration on the methyl orange removal were evaluated. For the initial concentration of 1150 mg/L, the COD removal was obtained as 90% under the conditions of electric current 2 A, residence time 40 min. The effluent path of the electrochemical cell was optimized, using the anode effluent instead of the top effluent, where the COD removal was increased to 93% and the corresponding energy consumption was decreased from 15.5 to 14.6 kW-hr/kg COD. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Effects of habitat isolation on the recovery of fish assemblages in experimentally defaunated stream pools in Arkansas

Treesearch

David George Lonzarich; Melvin L. Warren; Mary Ruth Elger Lonzrich

1998-01-01

The authors removed fish from pools in two Arkansas streams to determine recolonization rates and the effects of isolation (i.e., riffle length, riffle depth, distance to large source pools, and location), pool area, and assemblage size on recovery. To determine pool-specific recovery rates, the authors repeatedly snorkeled 12 pools over a 40-day recovery period....

Functionalized iron oxide/SBA-15 sorbent: investigation of adsorption performance towards glyphosate herbicide.

PubMed

Rivoira, Luca; Appendini, Marta; Fiorilli, Sonia; Onida, Barbara; Del Bubba, Massimo; Bruzzoniti, Maria Concetta

2016-11-01

Glyphosate is a worldwide-used herbicide occurring in many monitoring campaigns. Efficient technologies are currently unavailable for glyphosate removal from waters. In this work, a SBA-15 mesoporous silica-based material (Fe-NH 2 -SBA-15) was synthesized and studied for the adsorption of glyphosate from waters. In order to promote specific interactions between the sorbent and glyphosate via phosphoric group, iron oxide nanoparticles were encapsulated and a surface functionalization with (3-aminopropyl)triethoxysilane was accomplished. The adsorption of glyphosate on Fe-NH 2 -SBA-15 was investigated as a function of (i) pH, (ii) ionic strength (I), and (iii) adsorbate to adsorbent ratio (C), using a two-level, three-factor experimental design. The experimental design allowed for understanding the effect of the abovementioned variables and for proposing experimental conditions for quantitative removal (pH = 2.1, I = 1⋅10 -2  M and C = 0.35) under both batch and dynamic conditions. Interaction mechanism between glyphosate and Fe-NH 2 -SBA-15 sorbent was elucidated by studying the adsorption behavior of sorbents derived from the intermediate stages of synthesis and by desorption tests. Fe-NH 2 -SBA-15 sorbent can be quantitatively regenerated by 12.5 mM NaOH, and can be reused at least for five adsorption/desorption cycles. Quantitative removal of glyphosate from inlet and effluent wastewaters from a wastewater treatment plant is shown.

Guava (Psidium guajava) leaf powder: novel adsorbent for removal of methylene blue from aqueous solutions.

PubMed

Ponnusami, V; Vikram, S; Srivastava, S N

2008-03-21

Batch sorption experiments were carried out using a novel adsorbent, guava leaf powder (GLP), for the removal of methylene blue (MB) from aqueous solutions. Potential of GLP for adsorption of MB from aqueous solution was found to be excellent. Effects of process parameters pH, adsorbent dosage, concentration, particle size and temperature were studied. Temperature-concentration interaction effect on dye uptake was studied and a quadratic model was proposed to predict dye uptake in terms of concentration, time and temperature. The model conforms closely to the experimental data. The model was used to find optimum temperature and concentration that result in maximum dye uptake. Langmuir model represent the experimental data well. Maximum dye uptake was found to be 295mg/g, indicating that GLP can be used as an excellent low-cost adsorbent. Pseudo-first-order, pseudo-second order and intraparticle diffusion models were tested. From experimental data it was found that adsorption of MB onto GLP follow pseudo second order kinetics. External diffusion and intraparticle diffusion play roles in adsorption process. Free energy of adsorption (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were calculated to predict the nature of adsorption. Adsorption in packed bed was also evaluated.

Monoclonal antibody fragment removal mediated by mixed mode resins.

PubMed

O'Connor, Ellen; Aspelund, Matthew; Bartnik, Frank; Berge, Mark; Coughlin, Kelly; Kambarami, Mutsa; Spencer, David; Yan, Huiming; Wang, William

2017-05-26

Efforts to increase monoclonal antibody expression in cell culture can result in the presence of fragmented species requiring removal in downstream processing. Capto adhere, HEA Hypercel, and PPA Hypercel anion exchange/hydrophobic interaction mixed mode resins were evaluated for their fragment removal capabilities and found to separate large hinge IgG1 antibody fragment (LHF) from monomer. Removal of greater than 75% of LHF population occurred at pH 8 and low conductivity. The mechanism of fragment removal was investigated in two series of experiments. The first experimental series consisted of comparison to chromatographic behavior on corresponding single mode resins. Both single mode anion exchange and hydrophobic interaction resins failed to separate LHF. The second experimental series studied the impact of phase modifiers, ethylene glycol, urea, and arginine on the mixed mode mediated removal. The addition of ethylene glycol decreased LHF removal by half. Further decreases in LHF separation were seen upon incubation with urea and arginine. Therefore, it was discovered that the purification is the result of a mixed mode phenomena dominated by hydrophobic interaction and hydrogen bonding effects. The site of interaction between the LHF and mixed mode resin was determined by chemical labeling of lysine residues with sulfo-NHS acetate. The labeling identified the antibody hinge and light chain regions as mediating the fragment separation. Sequence analysis showed that under separation conditions, a hydrophobic proline patch and hydrogen bonding serine and threonine residues mediate the hinge interaction with the Capto adhere ligand. Additionally, a case study is presented detailing the optimization of fragment removal using Capto adhere resin to achieve purity and yield targets in a manufacturing facility. This study demonstrated that mixed mode resins can be readily integrated into commercial antibody platform processes when additional chromatographic abilities are required. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Bioretention Design to Improve Nitrogen Removal | Science ...

EPA Pesticide Factsheets

Bioretention has been shown to effectively remove a variety of stormwater stressors, including oil/grease, heavy metals, phosphorus, and ammonium. However, reported nitrate and total nitrogen removal performance is highly variable. The media typically used in bioretention installation is coarse-grained with low organic matter content, which facilitates high infiltration rates but fails to provide the anaerobic conditions and carbon availability necessary to promote nitrate removal by denitrification. EPA's research at the Urban Watershed Research Facility investigates the effects of media carbon amendments, introduced internal storage zones, plant type, and media volume on nitrogen removal. Initial bench-scale tests informed media and carbon amendment choices. A locally-available, sandy media with low organic matter content was added to eight experimental, pilot-scale rain gardens above a shallow pea gravel drainage layer. The media was separated from the pea gravel with a nonwoven geotextile. Double-shredded hardwood wood chips were chosen as a carbon amendment and added as a 20-cm layer 10 cm above the geotextile in four of the eight pilot-scale rain gardens; the other four did not receive the mulch layer. Four rain gardens were constructed with an elevated outlet pipe to create an internal storage zone; the other four drain freely. Pilot-scale rain gardens were constructed in tanks of two sizes to test the effects of media volume. After initial hydrologic

In-situ burning of oil in coastal marshes. 2. Oil spill cleanup efficiency as a function of oil type, marsh type, and water depth.

PubMed

Lin, Qianxin; Mendelssohn, Irving A; Carney, Kenneth; Miles, Scott M; Bryner, Nelson P; Walton, William D

2005-03-15

In-situ burning of spilled oil, which receives considerable attention in marine conditions, could be an effective way to cleanup wetland oil spills. An experimental in-situ burn was conducted to study the effects of oil type, marsh type, and water depth on oil chemistry and oil removal efficiency from the water surface and sediment. In-situ burning decreased the totaltargeted alkanes and total targeted polycyclic aromatic hydrocarbons (PAHs) in the burn residues as compared to the pre-burn diesel and crude oils. Removal was even more effective for short-chain alkanes and low ring-number PAHs. Removal efficiencies for alkanes and PAHs were >98% in terms of mass balance although concentrations of some long-chain alkanes and high ring-number PAHs increased in the burn residue as compared to the pre-burn oils. Thus, in-situ burning potentially prevents floating oil from drifting into and contaminating adjacent habitats and penetrating the sediment. In addition, in-situ burning significantly removed diesel oil that had penetrated the sediment for all water depths. Furthermore, in-situ burning at a water depth 2 cm below the soil surface significantly removed crude oil that had penetrated the sediment. As a result, in-situ burning may reduce the long-term impacts of oil on benthic organisms.

Enhanced magneto-optical imaging of internal stresses in the removed surface layer

NASA Astrophysics Data System (ADS)

Agalidi, Yuriy; Kozhukhar, Pavlo; Levyi, Sergii; Turbin, Dmitriy

2015-10-01

The paper describes a software method of reconstructing the state of the removed surface layer by visualising internal stresses in the underlying layers of the sample. Such a problem typically needs to be solved as part of forensic investigation that aims to reveal original marking of a sample with removed surface layer. For example, one may be interested in serial numbers of weapons or vehicles that had the surface layer of metal removed from the number plate. Experimental results of studying gradient internal stress fields in ferromagnetic sample using the NDI method of magneto-optical imaging (MOI) are presented. Numerical modelling results of internal stresses enclosed in the surface marking region are analysed and compared to the experimental results of magneto-optical imaging (MOI). MOI correction algorithm intended for reconstructing internal stress fields in the removed surface layer by extracting stresses retained by the underlying layers is described. Limiting ratios between parameters of a marking font are defined for the considered correction algorithm. Enhanced recognition properties for hidden stresses left by marking symbols are experimentally verified and confirmed.

Assessment of potential positive effects of nZVI surface modification and concentration levels on TCE dechlorination in the presence of competing strong oxidants, using an experimental design.

PubMed

Kaifas, Delphine; Malleret, Laure; Kumar, Naresh; Fétimi, Wafa; Claeys-Bruno, Magalie; Sergent, Michelle; Doumenq, Pierre

2014-05-15

Nanoscale zero-valent iron (nZVI) particles are efficient for the remediation of aquifers polluted by trichloroethylene (TCE). But for on-site applications, their reactivity can be affected by the presence of common inorganic co-pollutants, which are equally reduced by nZVI particles. The aim of this study was to assess the potential positive effects of nZVI surface modification and concentration level on TCE removal in the concomitant presence of two strong oxidants, i.e., Cr(VI) and NO3(-). A design of experiments, testing four factors (i.e. nZVI concentration, nZVI surface modification, Cr(VI) concentration and NO3(-) concentration), was used to select the best trials for the identification of the main effects of the factors and of the factors interactions. The effects of these factors were studied by measuring the following responses: TCE removal rates at different times, degradation kinetic rates, and the transformation products formed. As expected, TCE degradation was delayed or inhibited in most of the experiments, due to the presence of inorganics. The negative effects of co-pollutants can be palliated by combining surface modification with a slight increase in nZVI concentration. Encouragingly, complete TCE removal was achieved for some given experimental conditions. Noteworthily, nZVI surface modification was found to promote the efficient degradation of TCE. When degradation occurred, TCE was mainly transformed into innocuous non-chlorinated transformation products, while hazardous chlorinated transformation products accounted for a small percentage of the mass-balance. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

Removal of heavy metal species from industrial sludge with the aid of biodegradable iminodisuccinic acid as the chelating ligand.

PubMed

Wu, Qing; Duan, Gaoqi; Cui, Yanrui; Sun, Jianhui

2015-01-01

High level of heavy metals in industrial sludge was the obstacle of sludge disposal and resource recycling. In this study, iminodisuccinic acid (IDS), a biodegradable chelating ligand, was used to remove heavy metals from industrial sludge generated from battery industry. The extraction of cadmium, copper, nickel, and zinc from battery sludge with aqueous solution of IDS was studied under various conditions. It was found that removal efficiency greatly depends on pH, chelating agent's concentration, as well as species distribution of metals. The results showed that mildly acidic and neutral systems were not beneficial to remove cadmium. About 68 % of cadmium in the sample was extracted at the molar ratio of IDS to heavy metals 7:1 without pH adjustment (pH 11.5). Copper of 91.3 % and nickel of 90.7 % could be removed by IDS (molar ratio, IDS: metals = 1:1) with 1.2 % phosphoric acid effectively. Removal efficiency of zinc was very low throughout the experiment. Based on the experimental results, IDS could be a potentially useful chelant for heavy metal removal from battery industry sludge.

Experimental testing of spray dryer for control of incineration emissions.

PubMed

Wey, M Y; Wu, H Y; Tseng, H H; Chen, J C

2003-05-01

The research investigated the absorption/adsorption efficiency of sulfur dioxide (SO2), heavy metals, and polycyclic aromatic hydrocarbons (PAHs) with different Ca-based sorbents in a spray dryer during incineration process. For further improving the adsorption capacity of Ca-based sorbents, different spraying pressure and additives were carried out in this study. Experimental results showed that CaO could be used as an alternative sorbent in the spray dryer at an optimal initial particle size distribution of spraying droplet. In the spray dryer, Ca-based sorbents provided a lot of sites for heavy metals and PAHs condensing and calcium and alkalinity to react with metals to form merged species. As a result, heavy metals and PAHs could be removed from the flue gas simultaneously by condensation and adsorption. The additions of additives NaHCO3, SiO2, and KMnO4 were also found to be effective in improving the removal efficiency of these air pollutants.

MODELING THE AMBIENT CONDITION EFFECTS OF AN AIR-COOLED NATURAL CIRCULATION SYSTEM

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

Hu, Rui; Lisowski, Darius D.; Bucknor, Matthew

The Reactor Cavity Cooling System (RCCS) is a passive safety concept under consideration for the overall safety strategy of advanced reactors such as the High Temperature Gas-Cooled Reactor (HTGR). One such variant, air-cooled RCCS, uses natural convection to drive the flow of air from outside the reactor building to remove decay heat during normal operation and accident scenarios. The Natural convection Shutdown heat removal Test Facility (NSTF) at Argonne National Laboratory (“Argonne”) is a half-scale model of the primary features of one conceptual air-cooled RCCS design. The facility was constructed to carry out highly instrumented experiments to study the performancemore » of the RCCS concept for reactor decay heat removal that relies on natural convection cooling. Parallel modeling and simulation efforts were performed to support the design, operation, and analysis of the natural convection system. Throughout the testing program, strong influences of ambient conditions were observed in the experimental data when baseline tests were repeated under the same test procedures. Thus, significant analysis efforts were devoted to gaining a better understanding of these influences and the subsequent response of the NSTF to ambient conditions. It was determined that air humidity had negligible impacts on NSTF system performance and therefore did not warrant consideration in the models. However, temperature differences between the building exterior and interior air, along with the outside wind speed, were shown to be dominant factors. Combining the stack and wind effects together, an empirical model was developed based on theoretical considerations and using experimental data to correlate zero-power system flow rates with ambient meteorological conditions. Some coefficients in the model were obtained based on best fitting the experimental data. The predictive capability of the empirical model was demonstrated by applying it to the new set of experimental data. The empirical model was also implemented in the computational models of the NSTF using both RELAP5-3D and STARCCM+ codes. Accounting for the effects of ambient conditions, simulations from both codes predicted the natural circulation flow rates very well.« less

[Usefulness of haemoperfusion in the treatment of the severe septic patient: an update].

PubMed

Pestaña, D; Ojeda, N; Padrón, O M; Higuera, E; Rey, T; Aldecoa, C

2013-01-01

Haemoperfusion is an extracorporeal technique that removes endotoxin and/or inflammatory mediators by means of an adsorptive mechanism during the passage of the blood through a porous filter. Most of the studies in the literature use polymyxin B as the adsorptive agent. This treatment is based on the assumption that the removal of endotoxin and inflammatory mediators from the circulation attenuates the inflammatory response in sepsis. This review summarizes the theoretical basis, and the experimental and clinical results published to date with the use of haemoperfusion. Although most of the studies show positive results, some doubts have arisen about the suitability of the methods described (small number of cases, low quality of the experimental design, and excessive mortality in the control groups). There are also some inconsistencies regarding the theoretical basis of its use (lack of positive effects after the removal of endotoxin from the circulation using alternative mechanisms, discrepancies regarding the best moment to initiate the therapy, unexplained beneficial effects in the absence of increased endotoxin levels). It is the opinion of the authors that haemoperfusion represents a promising therapy for the treatment of sepsis, but consider that its usefulness requires confirmation in well designed studies before being included in protocols. Copyright © 2011 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

TREATMENT OF LANDFILL LEACHATE BY COUPLING COAGULATION-FLOCCULATION OR OZONATION TO GRANULAR ACTIVATED CARBON ADSORPTION.

PubMed

Oloibiri, Violet; Ufomba, Innocent; Chys, Michael; Audenaert, Wim; Demeestere, Kristof; Van Hulle, Stijn W H

2015-01-01

A major concern for landfilling facilities is the treatment of their leachate. To optimize organic matter removal from this leachate, the combination of two or more techniques is preferred in order to meet stringent effluent standards. In our study, coagulation-flocculation and ozonation are compared as pre- treatment steps for stabilized landfill leachate prior to granular activated carbon (GAC) adsorption. The efficiency of the pre treatment techniques is evaluated using COD and UVA254 measurements. For coagulation- flocculation, different chemicals are compared and optimal dosages are determined. After this, iron (III) chloride is selected for subsequent adsorption studies due to its high percentage of COD and UVA254 removal and good sludge settle-ability. Our finding show that ozonation as a single treatment is effective in reducing COD in landfill leachate by 66% compared to coagulation flocculation (33%). Meanwhile, coagulation performs better in UVA254 reduction than ozonation. Subsequent GAC adsorption of ozonated effluent, coagulated effluent and untreated leachate resulted in 77%, 53% and 8% total COD removal respectively (after 6 bed volumes). The effect of the pre-treatment techniques on GAC adsorption properties is evaluated experimentally and mathematically using Thomas and Yoon-Nelson models. Mathematical modelling of the experimental GAC adsorption data shows that ozonation increases the adsorption capacity and break through time with a factor of 2.5 compared to coagulation-flocculation.

Isotherm Modelling, Kinetic Study and Optimization of Batch Parameters Using Response Surface Methodology for Effective Removal of Cr(VI) Using Fungal Biomass

PubMed Central

Chidambaram, Ramalingam

2015-01-01

Biosorption is a promising alternative method to replace the existing conventional technique for Cr(VI) removal from the industrial effluent. In the present experimental design, the removal of Cr(VI) from the aqueous solution was studied by Aspergillus niger MSR4 under different environmental conditions in the batch systems. The optimum conditions of biosorption were determined by investigating pH (2.0) and temperature (27°C). The effects of parameters such as biomass dosage (g/L), initial Cr(VI) concentration (mg/L) and contact time (min) on Cr(VI) biosorption were analyzed using a three parameter Box–Behnken design (BBD). The experimental data well fitted to the Langmuir isotherm, in comparison to the other isotherm models tested. The results of the D-R isotherm model suggested that a chemical ion-exchange mechanism was involved in the biosorption process. The biosorption process followed the pseudo-second-order kinetic model, which indicates that the rate limiting step is chemisorption process. Fourier transform infrared (FT-IR) spectroscopic studies revealed the possible involvement of functional groups, such as hydroxyl, carboxyl, amino and carbonyl group in the biosorption process. The thermodynamic parameters for Cr(VI) biosorption were also calculated, and the negative ∆Gº values indicated the spontaneous nature of biosorption process. PMID:25786227

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.

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.

Microbial xylitol production from corn cobs using Candida magnoliae.

PubMed

Tada, Kiyoshi; Horiuchi, Jun-Ichi; Kanno, Tohru; Kobayashi, Masayoshi

2004-01-01

Microbial production of xylitol from corn cobs using Candida magnoliae was experimentally investigated. Approximately 25 g-xylose/l solution was obtained from 100 g-corn cobs/l solution by hydrolysis using 1.0% sulfuric acid at 121 degrees C for 60 min. To remove inhibitors from the hydrolysates, charcoal pellets were found to be effective in selectively removing the inhibitors from the hydrolysates without affecting xylose concentration. C. magnoliae was successfully cultivated using the treated corn cob hydrolysate, resulting in the production of 18.7 g-xylitol/l from 25 g-xylose/l within 36 h.

The color removal of dye wastewater by magnesium chloride/red mud (MRM) from aqueous solution.

PubMed

Wang, Qi; Luan, Zhaokun; Wei, Ning; Li, Jin; Liu, Chengxi

2009-10-30

In this study, the MgCl2/red mud system (MRM) was used to investigate the color removal efficiency of dye solutions. Parameters such as the effect of the dosage of red mud (RM) and MgCl2 have been studied. The effect of pH on the conversion rate of Mg2+ has also been studied. The color removal efficiency of MRM was compared with that of PAC/RM and PAC/NaOH. Meanwhile, the color removal efficiency of RM was compared with that of NaOH. The results show that the MRM system can remove more than 98% of the coloring material at a dosage of 25 g RM/L dye solution and a volume of 1.5 mL MgCl2/L dye solution in the decolorization process of reactive dye, acid dye and direct dye. The color removal efficiency was better than PAC/RM and PAC/NaOH system. The adsorption data have been analyzed using Langmuir and Freundlich isotherms. The results indicated that both models provide the best correlation of the experimental data. The decolorization mechanism of MRM was discussed, too. The MRM system was a viable alternative to some of the more conventional forms of chemical treatment of dye solutions and also provided another way to make use of industrial waste red mud.

Simultaneously efficient adsorption and photocatalytic degradation of tetracycline by Fe-based MOFs.

PubMed

Wang, Dongbo; Jia, Feiyue; Wang, Hou; Chen, Fei; Fang, Ying; Dong, Wenbo; Zeng, Guangming; Li, Xiaoming; Yang, Qi; Yuan, Xingzhong

2018-06-01

Recently, Fe-based metal-organic frameworks (MOFs) have attracted increasing attention and been widely used. To date, however, it is unknown whether they can be employed to degrade tetracycline, one of the most widely used antibiotics. This work therefore aims to provide such support by comparing the performance of three Fe-based MOFs (namely, Fe-MIL-101, Fe-MIL-100, and Fe-MIL-53) in removing tetracycline. Experimental results showed that Fe-MIL-101 exhibited the best performance in tetracycline removal, with 96.6% of tetracycline being removed (initial tetracycline concentration at 50 mg/L) while Fe-MIL-100 and Fe-MIL-53 removed 57.4% and 40.6% under the same conditions. Additionally, the effects of adding dosage, adsorption time, and initial concentration of tetracycline on degradation efficiency were examined. It was found that the adsorption and photocatalytic degradation effect was better with the increase of time, the optimum dosage of Fe-MIL-101 was 0.5 g/L and the removal efficiency decreased with the increasing of initial tetracycline concentrations. Moreover, the trapping experiments and ESR tests indicated that O 2 -, OH and h + were the main active species in photocatalytic degradation process of tetracycline. Due to its high removal efficiency and simple synthesis, it could be used as a potential catalyst for degradation of tetracycline and other antibiotics. Copyright © 2018 Elsevier Inc. All rights reserved.

Novel fabrication method of the peritoneal dialysis filter using silk fibroin with urease fixation system.

PubMed

Moon, Bo Mi; Choi, Myung-Jin; Sultan, Md Tipu; Yang, Jae Won; Ju, Hyung Woo; Lee, Jung Min; Park, Hyun Jung; Park, Ye Ri; Kim, Soo Hyeon; Kim, Dong Wook; Lee, Min Chae; Jeong, Ju Yeon; Lee, Ok Joo; Sung, Gun Yong; Park, Chan Hum

2017-10-01

During the last decade, there has been a great advance in the kidney dialysis system by wearable artificial kidney (WAK) system for end-stage renal disease patients. Uremic solute removal and water regeneration system are the most prerequisite for WAK to work properly. In this study, we designed a filtering membrane system by using immobilized urease silk fibroin filter and evaluated its comparative effectiveness with a PVDF filtering system in peritoneal dialysate regeneration system by urea removal efficacy. We evaluated this membrane's characteristic and performances by conducting SEM-EDX analyze, water-binding abilities and porosity test, removal abilities of urea, cytotoxicity assay and enzyme activity assay. Under the condition for optimization of urease, the percentage removal of urea was about 40% and 60% in 50 mg/dL urea solution by urease immobilized PVDF and silk fibroin scaffolds, respectively. The batch experimental result showed that immobilized filter removed more than 50% of urea in 50 mg/dL urea solution. In addition silk fibroin with urease filter removed 90 percent of urea in the peritoneal dialysate after 24 h filtration. We suggest that silk fibroin with urease fixation filter can be used more effectively for peritoneal dialysate regeneration system, which have hydrophilic property and prolonged enzyme activity. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2136-2144, 2017. © 2016 Wiley Periodicals, Inc.

Carbon and macronutrient loss during accelerated erosion under different tillage and residue management systems

USDA-ARS?s Scientific Manuscript database

The effects of tillage and crop residue removal on erosion and associated macronutrient fluxes on erodible soils subjected to a high intensity simulated rain event (70 mm/h) were investigated in an experimental watershed in Ohio, USA. A set of plots which constitute two experiments at this site were...

Impacts of pine species, stump removal, cultivation, and fertilization on soil properties half a century after planting

Treesearch

John R. Butnor; Kurt H. Johnsen; Felipe G Sanchez; C. Dana Nelson

2012-01-01

To better understand the long-term effects of species selection and forest management practices on soil quality and soil C retention, we analyzed soil samples from an experimental planting of loblolly (Pinus taeda L.), longleaf ((Pinus palustris Mill.), and slash ((Pinus elliottii Engelm.) pines under...

Improvement of MRR and surface roughness during electrical discharge machining (EDM) using aluminum oxide powder mixed dielectric fluid

NASA Astrophysics Data System (ADS)

Khan, A. A.; Mohiuddin, A. K. M.; Latif, M. A. A.

2018-01-01

This paper discusses the effect of aluminium oxide (Al203) addition to dielectric fluid during electrical discharge machining (EDM). Aluminium oxide was added to the dielectric used in the EDM process to improve its performance when machining the stainless steel AISI 304, while copper was used as the electrode. Effect of the concentration of Al203 (0.3 mg/L) in dielectric fluid was compared with EDM without any addition of Al203. Surface quality of stainless steel and the material removal rate were investigated. Design of the experiment (DOE) was used for the experimental plan. Statistical analysis was done using ANOVA and then appropriate model was designated. The experimental results show that with dispersing of aluminium oxide in dielectric fluid surface roughness was improved while the material removal rate (MRR) was increased to some extent. These indicate the improvement of EDM performance using aluminium oxide in dielectric fluid. It was also found that with increase in pulse on time both MRR and surface roughness increase sharply.

Adaptive Filtration of Physiological Artifacts in EEG Signals in Humans Using Empirical Mode Decomposition

NASA Astrophysics Data System (ADS)

Grubov, V. V.; Runnova, A. E.; Hramov, A. E.

2018-05-01

A new method for adaptive filtration of experimental EEG signals in humans and for removal of different physiological artifacts has been proposed. The algorithm of the method includes empirical mode decomposition of EEG, determination of the number of empirical modes that are considered, analysis of the empirical modes and search for modes that contains artifacts, removal of these modes, and reconstruction of the EEG signal. The method was tested on experimental human EEG signals and demonstrated high efficiency in the removal of different types of physiological EEG artifacts.

SEMICONDUCTOR TECHNOLOGY: Material removal rate in chemical-mechanical polishing of wafers based on particle trajectories

NASA Astrophysics Data System (ADS)

Jianxiu, Su; Xiqu, Chen; Jiaxi, Du; Renke, Kang

2010-05-01

Distribution forms of abrasives in the chemical mechanical polishing (CMP) process are analyzed based on experimental results. Then the relationships between the wafer, the abrasive and the polishing pad are analyzed based on kinematics and contact mechanics. According to the track length of abrasives on the wafer surface, the relationships between the material removal rate and the polishing velocity are obtained. The analysis results are in accord with the experimental results. The conclusion provides a theoretical guide for further understanding the material removal mechanism of wafers in CMP.

Process simulation and dynamic control for marine oily wastewater treatment using UV irradiation.

PubMed

Jing, Liang; Chen, Bing; Zhang, Baiyu; Li, Pu

2015-09-15

UV irradiation and advanced oxidation processes have been recently regarded as promising solutions in removing polycyclic aromatic hydrocarbons (PAHs) from marine oily wastewater. However, such treatment methods are generally not sufficiently understood in terms of reaction mechanisms, process simulation and process control. These deficiencies can drastically hinder their application in shipping and offshore petroleum industries which produce bilge/ballast water and produced water as the main streams of marine oily wastewater. In this study, the factorial design of experiment was carried out to investigate the degradation mechanism of a typical PAH, namely naphthalene, under UV irradiation in seawater. Based on the experimental results, a three-layer feed-forward artificial neural network simulation model was developed to simulate the treatment process and to forecast the removal performance. A simulation-based dynamic mixed integer nonlinear programming (SDMINP) approach was then proposed to intelligently control the treatment process by integrating the developed simulation model, genetic algorithm and multi-stage programming. The applicability and effectiveness of the developed approach were further tested though a case study. The experimental results showed that the influences of fluence rate and temperature on the removal of naphthalene were greater than those of salinity and initial concentration. The developed simulation model could well predict the UV-induced removal process under varying conditions. The case study suggested that the SDMINP approach, with the aid of the multi-stage control strategy, was able to significantly reduce treatment cost when comparing to the traditional single-stage process optimization. The developed approach and its concept/framework have high potential of applicability in other environmental fields where a treatment process is involved and experimentation and modeling are used for process simulation and control. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling of the acid-base properties of natural and synthetic adsorbent materials used for heavy metal removal from aqueous solutions.

PubMed

Pagnanelli, Francesca; Vegliò, Francesco; Toro, Luigi

2004-02-01

In this paper a comparison about kinetic behaviour, acid-base properties and copper removal capacities was carried out between two different adsorbent materials used for heavy metal removal from aqueous solutions: an aminodiacetic chelating resin as commercial product (Lewatit TP207) and a lyophilised bacterial biomass of Sphaerotilus natans. The acid-base properties of a S. natans cell suspension were well described by simplified mechanistic models without electrostatic corrections considering two kinds of weakly acidic active sites. In particular the introduction of two-peak distribution function for the proton affinity constants allows a better representation of the experimental data reproducing the site heterogeneity. A priori knowledge about resin functional groups (aminodiacetic groups) is the base for preliminary simulations of titration curve assuming a Donnan gel structure for the resin phase considered as a concentrated aqueous solution of aminodiacetic acid (ADA). Departures from experimental and simulated data can be interpreted by considering the heterogeneity of the functional groups and the effect of ionic concentration in the resin phase. Two-site continuous model describes adequately the experimental data. Moreover the values of apparent protonation constants (as adjustable parameters found by non-linear regression) are very near to the apparent constants evaluated by a Donnan model assuming the intrinsic constants in resin phase equal to the equilibrium constants in aqueous solution of ADA and considering the amphoteric nature of active sites for the evaluation of counter-ion concentration in the resin phase. Copper removal outlined the strong affinity of the active groups of the resin for this ion in solution compared to the S. natans biomass according to the complexation constants between aminodiacetic and mono-carboxylic groups and copper ions.

Uncoupling clutch size, prolactin, and luteinizing hormone using experimental egg removal.

PubMed

Ryan, Calen P; Dawson, Alistair; Sharp, Peter J; Williams, Tony D

2015-03-01

Clutch size is a key avian fitness and life history trait. A physiological model for clutch size determination (CSD), involving an anti-gonadal effect of prolactin (PRL) via suppression of luteinizing hormone (LH), was proposed over 20 years ago, but has received scant experimental attention since. The few studies looking at a PRL-based mechanistic hypothesis for CSD have been equivocal, but recent experiments utilizing a pharmacological agent to manipulate PRL in the zebra finch (Taeniopygia guttata) found no support for a role of this hormone in clutch size determination. Here, we take a complementary approach by manipulating clutch size through egg removal, examining co-variation in PRL and LH between two breeding attempts, as well as through experimentally-extended laying. Clutch size increased for egg removal females, but not controls, but this was not correlated with changes in PRL or LH. There were also no differences in PRL between egg removal females and controls, nor did PRL levels during early, mid- or late-laying of supra-normal clutches predict clutch size. By uncoupling PRL, LH and clutch size in our study, several key predictions of the PRL-based mechanistic model for CSD were not supported. However, a positive correlation between PRL levels late in laying and days relative to the last egg (clutch completion) provides an alternative explanation for the equivocal results surrounding the conventional PRL-based physiological model for CSD. We suggest that females coordinate PRL-mediated incubation onset with clutch completion to minimize hatching asynchrony and sibling hierarchy, a behavior that is amplified in females laying larger clutches. Copyright © 2015 Elsevier Inc. All rights reserved.

Intensification of ammonia removal from waste water in biologically active zeolitic ion exchange columns.

PubMed

Almutairi, Azel; Weatherley, Laurence R

2015-09-01

The use of nitrification filters for the removal of ammonium ion from waste-water is an established technology deployed extensively in municipal water treatment, in industrial water treatment and in applications such as fish farming. The process involves the development of immobilized bacterial films on a solid packing support, which is designed to provide a suitable host for the film, and allow supply of oxygen to promote aerobic action. Removal of ammonia and nitrite is increasingly necessary to meet drinking water and discharge standards being applied in the US, Europe and other places. Ion-exchange techniques are also effective for removal of ammonia (as the ammonium ion) from waste water and have the advantage of fast start-up times compared to biological filtration which in some cases may take several weeks to be fully operational. Here we explore the performance of ion exchange columns in which nitrifying bacteria are cultivated, with the goal of a "combined" process involving simultaneous ion-exchange and nitrification, intensified by in-situ aeration with a novel membrane module. There were three experimental goals. Firstly, ion exchange zeolites were characterized and prepared for comparative column breakthrough studies for ammonia removal. Secondly effective in-situ aeration for promotion of nitrifying bacterial growth was studied using a number of different membranes including polyethersulfone (PES), polypropylene (PP), nylon, and polytetra-fluoroethylene (PTFE). Thirdly the breakthrough performance of ion exchange columns filled with zeolite in the presence of aeration and in the presence of nitrifying bacteria was determined to establish the influence of biomass, and aeration upon breakthrough during ammonium ion uptake. The methodology adopted included screening of two types of the naturally occuring zeolite clinoptilolite for effective ammonia removal in continuous ion-exchange columns. Next, the performance of fixed beds of clinoptilolite in the presence of nitrifying bacteria is compared to that in columns in which only ion exchange is occurring. The aeration performance of each of the chosen membranes was compared experimentally using a newly developed membrane support module which is also described. Comparison of ammonia removal in columns equipped with in-situ aeration using each membrane was undertaken and the breakthrough characteristics determined. The results showed that ammonia removal in the presence of the nitrifiers was significantly intensified. Column operation with membrane aeration showed further enhancement of ammonia removal. The greatest enhancement was observed in the case of the polyethersulfone membrane (PES). It is concluded that combined nitrification and ion-exchange is significantly intensified in packed columns by in-situ aeration using a novel membrane module. There is significant potential for extending the ion-exchange cycle time and thus potential cost reduction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Efficient sorption and reduction of U(VI) on zero-valent iron-polyaniline-graphene aerogel ternary composite.

PubMed

Chen, Lili; Feng, Shaojie; Zhao, Donglin; Chen, Shaohua; Li, Feifei; Chen, Changlun

2017-03-15

In this work, zero-valent iron-polyaniline-graphene aerogel composite (Fe-PANI-GA) was prepared and applied in the removal of U(VI) from aqueous solutions by batch sorption experiments. The experimental results showed that the Fe-PANI-GA composite had an excellent removal capacity for the removal of U(VI) in acidic solutions. The results also showed that the maximum removal capacity of the Fe-PANI-GA toward U(VI) was 350.47mg/g at pH 5.5. The sorption kinetics data were well-described by pseudo-second-order. The sorption isotherms of U(VI) fitted well with Langmuir isotherm and exhibited better removal efficiency with the increase of temperature. The thermodynamic parameters (ΔG, ΔS, ΔH) indicated that the sorption of U(VI) on the Fe-PANI-GA was an endothermic and spontaneous process. Moreover, removal mechanisms were studied based on the results of XRD, FTIR and XPS. Both U(VI) sorption and partially reductive precipitation of U(VI) to U(IV) contributed to the removal of U(VI) on Fe-PANI-GA. Therefore, Fe-PANI-GA was an economic and effective material for the removal of uranium from nuclear waste in practical application. Copyright © 2016 Elsevier Inc. All rights reserved.

Pan-sharpening algorithm to remove thin cloud via mask dodging and nonsampled shift-invariant shearlet transform

NASA Astrophysics Data System (ADS)

Shi, Cheng; Liu, Fang; Li, Ling-Ling; Hao, Hong-Xia

2014-01-01

The goal of pan-sharpening is to get an image with higher spatial resolution and better spectral information. However, the resolution of the pan-sharpened image is seriously affected by the thin clouds. For a single image, filtering algorithms are widely used to remove clouds. These kinds of methods can remove clouds effectively, but the detail lost in the cloud removal image is also serious. To solve this problem, a pan-sharpening algorithm to remove thin cloud via mask dodging and nonsampled shift-invariant shearlet transform (NSST) is proposed. For the low-resolution multispectral (LR MS) and high-resolution panchromatic images with thin clouds, a mask dodging method is used to remove clouds. For the cloud removal LR MS image, an adaptive principal component analysis transform is proposed to balance the spectral information and spatial resolution in the pan-sharpened image. Since the clouds removal process causes the detail loss problem, a weight matrix is designed to enhance the details of the cloud regions in the pan-sharpening process, but noncloud regions remain unchanged. And the details of the image are obtained by NSST. Experimental results over visible and evaluation metrics demonstrate that the proposed method can keep better spectral information and spatial resolution, especially for the images with thin clouds.

Improvement of one-nucleon removal and total reaction cross sections in the Liège intranuclear-cascade model using Hartree-Fock-Bogoliubov calculations

NASA Astrophysics Data System (ADS)

Rodríguez-Sánchez, Jose Luis; David, Jean-Christophe; Mancusi, Davide; Boudard, Alain; Cugnon, Joseph; Leray, Sylvie

2017-11-01

The prediction of one-nucleon-removal cross sections by the Liège intranuclear-cascade model has been improved using a refined description of the matter and energy densities in the nuclear surface. Hartree-Fock-Bogoliubov calculations with the Skyrme interaction are used to obtain a more realistic description of the radial-density distributions of protons and neutrons, as well as the excitation-energy uncorrelation at the nuclear surface due to quantum effects and short-range correlations. The results are compared with experimental data covering a large range of nuclei, from carbon to uranium, and projectile kinetic energies. We find that the new approach is in good agreement with experimental data of one-nucleon-removal cross sections covering a broad range in nuclei and energies. The new ingredients also improve the description of total reaction cross sections induced by protons at low energies, the production cross sections of heaviest residues close to the projectile, and the triple-differential cross sections for one-proton removal. However, other observables such as quadruple-differential cross sections of coincident protons do not present any sizable sensitivity to the new approach. Finally, the model is also tested for light-ion-induced reactions. It is shown that the new parameters can give a reasonable description of the nucleus-nucleus total reaction cross sections at high energies.

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.

Efficacy of Er,Cr:YSGG Laser in Removing Smear Layer and Debris with Two Different Output Powers

PubMed Central

Bolhari, Behnam; Ehsani, Sara; Etemadi, Ardavan; Shafaq, Mohammad

2014-01-01

Abstract Objective: The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls. Background data: Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space. Methods: Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers. Results: The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas. Conclusions: This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers. PMID:25198390

Efficacy of Er,Cr:YSGG laser in removing smear layer and debris with two different output powers.

PubMed

Bolhari, Behnam; Ehsani, Sara; Etemadi, Ardavan; Shafaq, Mohammad; Nosrat, Ali

2014-10-01

The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls. Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space. Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers. The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas. This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers.

PREditOR: a synthetic biology approach to removing heterochromatin from cells.

PubMed

Molina, Oscar; Carmena, Mar; Maudlin, Isabella E; Earnshaw, William C

2016-12-01

It is widely accepted that heterochromatin is necessary to maintain genomic stability. However, direct experimental evidence supporting this is slim. Previous studies using either enzyme inhibitors, gene knockout or knockdown studies all are subject to the caveat that drugs may have off-target effects and enzymes that modify chromatin proteins to support heterochromatin formation may also have numerous other cellular targets as well. Here, we describe PREditOR (protein reading and editing of residues), a synthetic biology approach that allows us to directly remove heterochromatin from cells without either drugs or global interference with gene function. We find that removal of heterochromatin perturbs mitotic progression and causes a dramatic increase in chromosome segregation defects, possibly as a result of interfering with the normal centromeric localization of the chromosomal passenger complex.

CO2 removal by solid amine sorbents. 1: Experimental studies of amine resin IR-45 with regard to spacecraft applications. 2: Computer program for predicting the transient performance of solid amine sorbent systems

NASA Technical Reports Server (NTRS)

Wright, R. M.; Hwang, K. C.

1973-01-01

The sorbent behavior of solid amine resin IR-45 with regard to potential use in regenerative CO2-removal systems for manned spacecraft is considered. Measurements of equilibrium sorption capacity of IR-45 for water and for CO2 are reported, and the dynamic mass transfer behavior of IR-45 beds is studied under conditions representative of those expected in a manned spacecraft. A digital computer program was written for the transient performance prediction of CO2 removal systems comprised of solid amine beds. Also evaluated are systems employing inorganic molecular-sieve sorbents. Tests show that there is definitely an effect of water loading on the absorption rate.

Hydroxyapatite-gelatin nanocomposite as a novel adsorbent for nitrobenzene removal from aqueous solution

NASA Astrophysics Data System (ADS)

Wei, Wei; Sun, Rong; Jin, Zhu; Cui, Jing; Wei, Zhenggui

2014-02-01

A novel adsorbent of hydroxyapatite-gelatin (HAP-GEL) nanocomposite was developed for nitrobenzene removal from aqueous solution. The adsorbent was characterized and its performance in nitrobenzene removal was evaluated. The effects of contact time, adsorbent dosage, temperature, pH, ionic strength, humic acid, and the presence of solvent on nitrobenzene adsorption, as well as the thermodynamic parameters for adsorption equilibrium were also investigated. Results showed that HAP-GEL nanocomposite possessed good adsorption ability to nitrobenzene. The adsorption process was fast, and it reached a steady state after only 1 min. Nitrobenzene removal was increased with an increasing amount of adsorbent dosage but decreased as the temperature and pH increased. Meanwhile the amount of nitrobenzene adsorbed decreased with an increase of ionic strength from 0.01 to 1.0 mol/L and humic acid from 10 to 50 mg/L. The adsorption isotherm studies showed that both Langmuir and Freundlich models could fit the experimental data well, and the maximum adsorption capacity was estimated to be 42.373 mg/g. The thermodynamic parameters suggested that the adsorption of nitrobenzene on HAP-GEL nanocomposite was physisorption, spontaneous and exothermic in nature. Findings of this study demonstrated the potential utility of the HAP-GEL nanocomposite as an effective adsorbent for nitrobenzene removal from aqueous solution.

The use of macroalgae (Gracilaria changii) as bio-adsorbent for Copper (II) removal

NASA Astrophysics Data System (ADS)

Lavania-Baloo; Idayu, Nordin; Umar Salihi, Ibrahim; Zainoddin, Jamari

2017-05-01

Biosorption of heavy metals using marine macroalgae biomass can be an effective process and alternative to conventional methods. Activated carbon was developed from macroalgae (Gracilaria changii) and used as adsorbents for the removal of copper (II) from wastewater. Gracilaria changii based activated carbon (GCBAC) was prepared using muffle furnace at a constant temperature of 300 °C for 1 hour. Batch adsorption experiments were conducted to investigate the effets of important parameters such as pH, contact time, initial metal concentration and adsorbent dosage on the removal of Cu (II) from synthetic aqueous solution. Batch adsorption study shows that removal of Cu (II) using GCBAC relied upon pH, contact time, initial metal concentration and GCBAC dosage. The optimum conditions parameters were found to be pH 6.0, time of 60 minutes and GCBAC dosage of 0.3 g, respectively. Adsorption data was described better by Freundlich isotherm model with R2 value of 0.7936. The maximum Cu (II) adsorption capacity of GCBAC was found to be 0.07 mg/g. The experimental adsorption data obtained fitted well into Pseudo-second-order kinetic model, with R2 value near unity. Thus, GCBAC can be used as an effective adsorbent for the removal of Cu (II) from aqueous solution.

Do predators control prey species abundance? An experimental test with brown treesnakes on Guam

USGS Publications Warehouse

Campbell, Earl W.; Yackel Adams, Amy A.; Converse, Sarah J.; Fritts, Thomas H.; Rodda, Gordon H.

2012-01-01

The effect of predators on the abundance of prey species is a topic of ongoing debate in ecology; the effect of snake predators on their prey has been less debated, as there exists a general consensus that snakes do not negatively influence the abundance of their prey. However, this viewpoint has not been adequately tested. We quantified the effect of brown treesnake (Boiga irregularis) predation on the abundance and size of lizards on Guam by contrasting lizards in two 1-ha treatment plots of secondary forest from which snakes had been removed and excluded vs. two 1-ha control plots in which snakes were monitored but not removed or excluded. We removed resident snakes from the treatment plots with snake traps and hand capture, and snake immigration into these plots was precluded by electrified snake barriers. Lizards were sampled in all plots quarterly for a year following snake elimination in the treatment plots. Following the completion of this experiment, we used total removal sampling to census lizards on a 100-m2 subsample of each plot. Results of systematic lizard population monitoring before and after snake removal suggest that the abundance of the skink, Carlia ailanpalai, increased substantially and the abundance of two species of gekkonids, Lepidodactylus lugubris and Hemidactylus frenatus, also increased on snake-free plots. No treatment effect was observed for the skink Emoia caeruleocauda. Mean snout–vent length of all lizard species only increased following snake removal in the treatment plots. The general increase in prey density and mean size was unexpected in light of the literature consensus that snakes do not control the abundance of their prey species. Our findings show that, at least where alternate predators are lacking, snakes may indeed affect prey populations.

Microbiota in experimental periodontitis and peri-implantitis in dogs.

PubMed

Charalampakis, Georgios; Abrahamsson, Ingemar; Carcuac, Olivier; Dahlén, Gunnar; Berglundh, Tord

2014-09-01

To analyze the microbial profile around teeth and implants following ligature removal in experimental periodontitis and peri-implantitis in dogs. Four implants with similar geometry and with two different surface characteristics (implant A: turned/implant B: TiUnite; NobelBiocare AB) were placed pairwise in the right side of the mandible 3 months after tooth extraction in five dogs. Experimental periodontitis and peri-implantitis were initiated 3 months later by ligature placement around implants and mandibular premolars and plaque formation. The ligatures were removed after 10 weeks. Microbial samples were obtained using paper points immediately after ligature removal, at 10 and 25 weeks after ligature removal. The microbiological analysis was performed by "checkerboard" DNA-DNA hybridization, including a panel of 16 bacterial species. The amount of bone loss that occurred during the period following ligature removal was significantly larger at implants with a modified surface than at implants with a turned surface and at teeth. The microbiological analysis revealed that the total bacterial load increased during the period following ligature removal and established an anaerobic Gram-negative microflora. It is suggested that the large variation in regard to the microbial profiles makes interpretation of a correlation between disease progression and microbial profiles difficult. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Abatement of Azo Dye from Wastewater Using Bimetal-Chitosan

PubMed Central

Asgari, Ghorban; Farjadfard, Sima

2013-01-01

We introduce a new adsorbent, bimetallic chitosan particle (BCP) that is successfully synthesized and applied to remove the orange II dye from wastewater. The effects of pH, BCP quantity, and contact time are initially verified on the basis of the percentage of orange II removed from the wastewater. Experimental data reveal that the Cu/Mg bimetal and chitosan have a synergistic effect on the adsorption process of the adsorbate, where the dye adsorption by Cu/Mg bimetal, chitosan alone, and bimetal-chitosan is 10, 49, and 99.5%, respectively. The time required for the complete decolorization of orange II by 1 mg/L of BCP is 10 min. The Langmuir model is the best fit for the experimental data, which attains a maximum adsorption capacity of 384.6 mg/g. The consideration of the kinetic behavior indicates that the adsorption of orange II onto the BCP fits best with the pseudo-second-order and Elovich models. Further, the simulated azo dye wastewater can be effectively treated using a relatively low quantity of the adsorbent, 1 mg/L, within a short reaction time of 20 min. Overall, the use of BCP can be considered a promising method for eliminating the azo dye from wastewater effectively. PMID:24348163

Modeling and evaluating of surface roughness prediction in micro-grinding on soda-lime glass considering tool characterization

NASA Astrophysics Data System (ADS)

Cheng, Jun; Gong, Yadong; Wang, Jinsheng

2013-11-01

The current research of micro-grinding mainly focuses on the optimal processing technology for different materials. However, the material removal mechanism in micro-grinding is the base of achieving high quality processing surface. Therefore, a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography is proposed in this paper. The differences of material removal mechanism between convention grinding process and micro-grinding process are analyzed. Topography characterization has been done on micro-grinding tools which are fabricated by electroplating. Models of grain density generation and grain interval are built, and new predicting model of micro-grinding surface roughness is developed. In order to verify the precision and application effect of the surface roughness prediction model proposed, a micro-grinding orthogonally experiment on soda-lime glass is designed and conducted. A series of micro-machining surfaces which are 78 nm to 0.98 μm roughness of brittle material is achieved. It is found that experimental roughness results and the predicting roughness data have an evident coincidence, and the component variable of describing the size effects in predicting model is calculated to be 1.5×107 by reverse method based on the experimental results. The proposed model builds a set of distribution to consider grains distribution densities in different protrusion heights. Finally, the characterization of micro-grinding tools which are used in the experiment has been done based on the distribution set. It is concluded that there is a significant coincidence between surface prediction data from the proposed model and measurements from experiment results. Therefore, the effectiveness of the model is demonstrated. This paper proposes a novel method for predicting surface roughness in micro-grinding of hard brittle materials considering micro-grinding tool grains protrusion topography, which would provide significant research theory and experimental reference of material removal mechanism in micro-grinding of soda-lime glass.

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.

Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

PubMed

He, Y F; Zhang, L; Yan, D Z; Liu, S L; Wang, H; Li, H R; Wang, R M

2012-01-01

In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200-1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%).

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.

Crack propagation and the material removal mechanism of glass-ceramics by the scratch test.

PubMed

Qiu, Zhongjun; Liu, Congcong; Wang, Haorong; Yang, Xue; Fang, Fengzhou; Tang, Junjie

2016-12-01

To eliminate the negative effects of surface flaws and subsurface damage of glass-ceramics on clinical effectiveness, crack propagation and the material removal mechanism of glass-ceramics were studied by single and double scratch experiments conducted using an ultra-precision machine. A self-manufactured pyramid shaped single-grit tool with a small tip radius was used as the scratch tool. The surface and subsurface crack propagations and interactions, surface morphology and material removal mechanism were investigated. The experimental results showed that the propagation of lateral cracks to the surface and the interaction between the lateral cracks and radial cracks are the two main types of material peeling, and the increase of the scratch depth increases the propagation angle of the radial cracks and the interaction between the cracks. In the case of a double scratch, the propagation of lateral cracks and radial cracks between paired scratches results in material peeling. The interaction between adjacent scratches depends on the scratch depth and separation distance. There is a critical separation distance where the normalized material removal volume reaches its peak. These findings can help reduce surface flaws and subsurface damage induced by the grinding process and improve the clinical effectiveness of glass-ceramics used as biological substitute and repair materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combined Effects of Early Season Leaf Removal and Climatic Conditions on Aroma Precursors in Sauvignon Blanc Grapes.

PubMed

Sivilotti, Paolo; Falchi, Rachele; Herrera, Jose Carlos; Škvarč, Branka; Butinar, Lorena; Sternad Lemut, Melita; Bubola, Marijan; Sabbatini, Paolo; Lisjak, Klemen; Vanzo, Andreja

2017-09-27

Early leaf removal around the cluster zone is a common technique applied in cool climate viticulture, to regulate yield components and improve fruit quality. Despite the increasing amount of information on early leaf removal and its impact on total soluble solids, anthocyanins, and polyphenols, less is known regarding aroma compounds. In order to verify the hypothesis that defoliation, applied before or after flowering, could impact the biosynthesis of thiol precursors, we performed a two year (2013 and 2014) experiment on Sauvignon blanc. We provided evidence that differential accumulation of thiol precursors in berries is affected by the timing of defoliation, and this impact was related to modifications in the biosynthetic pathway. Furthermore, the possible interaction between leaf removal treatment and seasonal weather conditions, and its effect on the biosynthesis of volatile precursors are discussed. Our results suggested that in Sauvignon blanc the relative proportion of 4-S-glutathionyl-4-methylpentan-2-one (G-4MSP) and 3-S-glutathionylhexan-1-ol (G-3SH) precursors can be affected by defoliation, and this could be related to the induction of two specific genes encoding glutathione-S-transferases (VvGST3 and VvGST5), while no significant effects on basic fruit chemical parameters, polyphenols, and methoxypyrazines were ascertained under our experimental conditions.

Spatial variation in post-dispersal seed removal in an Atlantic forest: Effects of habitat, location and guilds of seed predators

NASA Astrophysics Data System (ADS)

Christianini, Alexander V.; Galetti, Mauro

2007-11-01

Studies of post-dispersal seed removal in the Neotropics have rarely examined the magnitude of seed removal by different types of granivores. The relative impact of invertebrates, small rodents, and birds on seed removal was investigated in a 2,178 ha Atlantic forest fragment in southeastern Brazil. We used popcorn kernels ( Zea mays—Poaceae) to investigate seed removal in a series of selective exclosure treatments in a replicated, paired design experiment that included forest understory, gaps, and forest edge sites. We recorded the vegetation around the experimental seed stations in detail in order to evaluate the influence of microhabitat traits on seed removal. Vertebrate granivores (rodents and birds) were surveyed to determine whether granivore abundance was correlated with seed removal levels. Seed removal varied spatially and in unpredictable ways at the study site. Seed encounter and seed use varied with treatments, but not with habitat type. However, seed removal by invertebrates was negatively correlated with gap-related traits, which suggested an avoidance of large gaps by granivorous ants. The abundance of small mammals was remarkably low, but granivorous birds (tinamous and doves) were abundant at the study site. Birds were the main seed consumers in open treatments, but there was no correlation between local granivorous bird abundance and seed removal. These results emphasize the stochastic spatial pattern of seed removal, and, contrary to previous studies, highlight the importance of birds as seed predators in forest habitats.

Arsenic removal by solar-driven membrane distillation: modeling and experimental investigation with a new flash vaporization module.

PubMed

Pa, Parimal; Manna, Ajay Kumar; Linnanen, Lassi

2013-01-01

A modeling and simulation study was carried out on a new flux-enhancing and solar-driven membrane distillation module for removal of arsenic from contaminated groundwater. The developed new model was validated with rigorous experimental investigations using arsenic-contaminated groundwater. By incorporating flash vaporization dynamics, the model turned out to be substantially different from the existing direct contact membrane distillation models and could successfully predict (with relative error of only 0.042 and a Willmott d-index of 0.997) the performance of such an arsenic removal unit where the existing models exhibited wide variation with experimental findings in the new design. The module with greater than 99% arsenic removal efficiency and greater than 50 L/m2 x h flux could be implemented in arsenic-affected villages in Southeast Asian countries with abundant solar energy, and thus could give relief to millions of affected people. These encouraging results will raise scale-up confidence.

An Automatic Quality Control Pipeline for High-Throughput Screening Hit Identification.

PubMed

Zhai, Yufeng; Chen, Kaisheng; Zhong, Yang; Zhou, Bin; Ainscow, Edward; Wu, Ying-Ta; Zhou, Yingyao

2016-09-01

The correction or removal of signal errors in high-throughput screening (HTS) data is critical to the identification of high-quality lead candidates. Although a number of strategies have been previously developed to correct systematic errors and to remove screening artifacts, they are not universally effective and still require fair amount of human intervention. We introduce a fully automated quality control (QC) pipeline that can correct generic interplate systematic errors and remove intraplate random artifacts. The new pipeline was first applied to ~100 large-scale historical HTS assays; in silico analysis showed auto-QC led to a noticeably stronger structure-activity relationship. The method was further tested in several independent HTS runs, where QC results were sampled for experimental validation. Significantly increased hit confirmation rates were obtained after the QC steps, confirming that the proposed method was effective in enriching true-positive hits. An implementation of the algorithm is available to the screening community. © 2016 Society for Laboratory Automation and Screening.

Biodegradable alternative for removing toxic compounds from sugarcane bagasse hemicellulosic hydrolysates for valorization in biorefineries.

PubMed

Silva-Fernandes, T; Santos, J C; Hasmann, F; Rodrigues, R C L B; Izario Filho, H J; Felipe, M G A

2017-11-01

Among the major challenges for hemicellulosic hydrolysate application in fermentative processes, there is the presence of toxic compounds generated during the pretreatment of the biomass, which can inhibit microbial growth. Therefore, the development of efficient, biodegradable and cost-effective detoxification methods for lignocellulosic hydrolysates is crucial. In this work, two tannin-based biopolymers (called A and B) were tested in the detoxification of sugarcane bagasse hydrolysate for subsequent fermentation by Candida guilliermondii. The effects of biopolymer concentration, pH, temperature, and contact time were studied using a 2 4 experimental design for both biopolymers. Results revealed that the biopolymer concentration and the pH were the most significant factors in the detoxification step. Biopolymer A removed phenolics, 5-hydroxymethylfurfural, and nickel from the hydrolysate more efficiently than biopolymer B, while biopolymer B was efficient to remove chromium at 15% (v/v). Detoxification enhanced the fermentation of sugarcane bagasse hydrolysate, and the biopolymers showed different influences on the process. Copyright © 2017 Elsevier Ltd. 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.

Study on elimination of screening-current-induced field in pancake-type non-insulated HTS coil

NASA Astrophysics Data System (ADS)

Kim, K. L.; Song, J. B.; Yang, D. G.; Kim, Y. G.; Kim, T. H.; Kim, S. K.; Park, M. W.; Lee, H. G.

2016-03-01

This paper presents the details of a recent study on the removal of the screening-current-induced field (SCIF) in a pancake-type non-insulated high-temperature superconductor coil (NI coil). To determine the SCIF in the NI coil, the magnetic flux density (B z ) was calculated using the equivalent circuit model of the coil and compared to the B z obtained empirically. The experimental results indicate that the SCIF elimination in the NI coil was enhanced upon increasing the amplitude and frequency of the AC current being supplied to the background coil. Moreover, the SCIF in the NI coil was successfully removed by applying the appropriate external AC magnetic field intensity. This is because the magnetization direction of the SCIF changed completely from radial to spiral, a phenomenon termed the ‘vortex shaking effect.’ Overall, this study confirmed that the SCIF in a pancake-type NI coil can be effectively removed by exposing the coil to an external AC magnetic field.

Ca removal and Mg recovery from flue gas desulfurization (FGD) wastewater by selective precipitation.

PubMed

Xia, Min; Ye, Chunsong; Pi, Kewu; Liu, Defu; Gerson, Andrea R

2017-11-01

Selective removal of Ca and recovery of Mg by precipitation from flue gas desulfurization (FGD) wastewater has been investigated. Thermodynamic analysis of four possible additives, Na 2 CO 3 , Na 2 C 2 O 4 , NaF and Na 2 SO 4 , indicated that both carbonate and oxalate could potentially provide effective separation of Ca via precipitation from Mg in FGD wastewater. However, it was found experimentally that the carbonate system was not as effective as oxalate in this regard. The oxalate system performed considerably better, with Ca removal efficiency of 96% being obtained, with little Mg inclusion at pH 6.0 when the dosage was ×1.4 the stoichiometric requirement. On this basis, the subsequent recovery process for Mg was carried out using NaOH with two-step precipitation. The product was confirmed to be Mg(OH) 2 (using X-ray diffraction and thermo gravimetric analysis) with elemental analysis suggesting a purity of 99.3 wt.%.

Evaluation of Zeolite Permeable Treatment Wall for the Removal of Strontium-90 from Groundwater

NASA Astrophysics Data System (ADS)

Seneca, S. M.; Bronner, C.; Ross, E.; Rabideau, A. J.

2009-05-01

Experimental and modeling studies have been initiated to evaluate the potential performance of a permeable treatment wall comprised of zeolite-rich rock for the removal of strontium-90 from groundwater. Preliminary column studies were performed using a synthetic groundwater referenced to anticipate field conditions, with a focus on quantifying the competitive ion exchange among five cations (Na+, K+, Ca2+, Mg2+, and Sr2+). Variations of the column configurations addressed the effects of particle size and flow rates on removal efficiency. In general, kinetic effects were not significant for the test conditions. Ongoing studies are focused on the comparison of zeolites obtained from two sources: Teague Mineral Products (Adrian, OR) and Bear River Zeolite (Preston, UT), and on the possible influence of native soil that is mixed with treatment wall material during construction. The results of the performance assessment will support the possible deployment of a full scale treatment wall at a Western New York nuclear facility.

Tribochemical investigation of microelectronic materials

NASA Astrophysics Data System (ADS)

Kulkarni, Milind Sudhakar

To achieve efficient planarization with reduced device dimensions in integrated circuits, a better understanding of the physics, chemistry, and the complex interplay involved in chemical mechanical planarization (CMP) is needed. The CMP process takes place at the interface of the pad and wafer in the presence of the fluid slurry medium. The hardness of Cu is significantly less than the slurry abrasive particles which are usually alumina or silica. It has been accepted that a surface layer can protect the Cu surface from scratching during CMP. Four competing mechanisms in materials removal have been reported: the chemical dissolution of Cu, the mechanical removal through slurry abrasives, the formation of thin layer of Cu oxide and the sweeping surface material by slurry flow. Despite the previous investigation of Cu removal, the electrochemical properties of Cu surface layer is yet to be understood. The motivation of this research was to understand the fundamental aspects of removal mechanisms in terms of electrochemical interactions, chemical dissolution, mechanical wear, and factors affecting planarization. Since one of the major requirements in CMP is to have a high surface finish, i.e., low surface roughness, optimization of the surface finish in reference to various parameters was emphasized. Three approaches were used in this research: in situ measurement of material removal, exploration of the electropotential activation and passivation at the copper surface and modeling of the synergistic electrochemical-mechanical interactions on the copper surface. In this research, copper polishing experiments were conducted using a table top tribometer. A potentiostat was coupled with this tribometer. This combination enabled the evaluation of important variables such as applied pressure, polishing speed, slurry chemistry, pH, materials, and applied DC potential. Experiments were designed to understand the combined and individual effect of electrochemical interactions as well as mechanical impact during polishing. Extensive surface characterization was performed with AFM, SEM, TEM and XPS. An innovative method for direct material removal measurement on the nanometer scale was developed and used. Experimental observations were compared with the theoretically calculated material removal rate values. The synergistic effect of all of the components of the process, which result in a better quality surface finish was quantitatively evaluated for the first time. Impressed potential during CMP proved to be a controlling parameter in the material removal mechanism. Using the experimental results, a model was developed, which provided a practical insight into the CMP process. The research is expected to help with electrochemical material removal in copper planarization with low-k dielectrics.

Translating evidence-based protocol of wound drain management for total joint arthroplasty into practice: A quasi-experimental study.

PubMed

Tsang, Lap Fung; Cheng, Hang Cheong; Ho, Hon Shuen; Hsu, Yung Chak; Chow, Chiu Man; Law, Heung Wah; Fong, Lup Chau; Leung, Lok Ming; Kong, Ivy Ching Yan; Chan, Chi Wai; Sham, Alice So Yuen

2016-05-01

Although various drains have long been used in total joint replacement, evidence suggests inconsistent practice exists in the use of drainage systems including intermittently applying suction or free of drainage suction, and variations in the optimal timing for wound drain removal. A comprehensive systematic review of available evidence up to 2013 was conducted in a previous study and a protocol was adapted for clinical application according to the summary of the retrieved information (Tsang, 2015). To determine if the protocol could reduce blood loss and blood transfusion after operation and to develop a record form so as to enhance communication of drainage record amongst surgeons and nurses. A quasi-experimental time-series design was undertaken. In the conventional group, surgeons ordered free drainage if the drain output was more than 300 ml. The time of removal of the drain was based on their professional judgement. In the protocol group the method of drainage was dependant of the drainage output as was the timing of the removal of the drain. A standardized record form was developed to guide operating room and orthopaedic ward nurses to manage the drainage system. The drain was removed significantly earlier in the protocol group. Blood loss rate at the first hour of post-operation was extremely low in the protocol group due to clamping effect. Blood loss in volume during the first three hours in the protocol group was significantly lower than that in the conventional group. Only in 11.1% and 4% of cases was it necessary to clamp at the three and four hour post-operative hours. No clamping was required at the two and eight hour postoperative period. There was no significant difference in blood loss during the removal of the drain and during blood transfusion, which was required for patients upon removal of the drain in the two groups. This is the first clinical study to develop an evidence-based protocol to manage wound drain effectively in Hong Kong. Total blood loss and blood transfusions were not significantly different between the conventional and protocol groups. A standard documentation document is beneficial to enhance communication between doctors and nurses as well as to monitor and observe drainage effectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Experimental Comparison of Efficiency of First Aid Dressings in Burning White Phosphorus on Bacon Model.

PubMed

Witkowski, Wojciech; Surowiecka-Pastewka, Agnieszka; Biesaga, Magdalena; Gierczak, Tomasz

2015-08-12

The aim of this study was to determine effectiveness of first aid dressings in extinguishing burning white phosphorous (WP), eliminating WP pieces from the surface, inhibiting re-ignition on the model (fresh bacon covered with military uniform), and preventing from late re-ignition caused by persistent WP pieces. Burning WP was extinguished with several dressings: tactical Military Dressing (WJ10), wet gauze, 2 hydrocolloids, and 3 prototypes of hydrocolloids developed by the authors. All examined dressings were effective in extinguishing WP provided that the entire area of the burning substance was completely covered. Moist gauze was especially effective in extinguishing WP, and also removed and absorbed the majority of the WP mass, preventing deeper penetration of WP particles. The immediate re-ignition was observed when all the remaining examined dressings were removed from the bacon. A stream of water was dangerous, as it splashed and transferred pieces of WP around. Moist gauze placed on burning WP for approximately 3 min was most effective in extinguishing WP and removing most of the WP pieces. We recommend moist gauze, used once or twice, as the best primary means for WP elimination and preventing tissue penetration. As a dressing used for medical evacuation (MEDEVAC), or as a second step after complete removal of visible WP, innovative hydrocolloid or hydrogel dressings should be used.

Experimental Comparison of Efficiency of First Aid Dressings in Burning White Phosphorus on Bacon Model

PubMed Central

Witkowski, Wojciech; Surowiecka-Pastewka, Agnieszka; Biesaga, Magdalena; Gierczak, Tomasz

2015-01-01

Background The aim of this study was to determine effectiveness of first aid dressings in extinguishing burning white phosphorous (WP), eliminating WP pieces from the surface, inhibiting re-ignition on the model (fresh bacon covered with military uniform), and preventing from late re-ignition caused by persistent WP pieces. Material/Methods Burning WP was extinguished with several dressings: tactical Military Dressing (WJ10), wet gauze, 2 hydrocolloids, and 3 prototypes of hydrocolloids developed by the authors. Results All examined dressings were effective in extinguishing WP provided that the entire area of the burning substance was completely covered. Moist gauze was especially effective in extinguishing WP, and also removed and absorbed the majority of the WP mass, preventing deeper penetration of WP particles. The immediate re-ignition was observed when all the remaining examined dressings were removed from the bacon. A stream of water was dangerous, as it splashed and transferred pieces of WP around. Conclusions Moist gauze placed on burning WP for approximately 3 min was most effective in extinguishing WP and removing most of the WP pieces. We recommend moist gauze, used once or twice, as the best primary means for WP elimination and preventing tissue penetration. As a dressing used for medical evacuation (MEDEVAC), or as a second step after complete removal of visible WP, innovative hydrocolloid or hydrogel dressings should be used. PMID:26264209

Passive neutralization of acid mine drainage using basic oxygen furnace slag as neutralization material: experimental and modelling.

PubMed

Zvimba, John N; Siyakatshana, Njabulo; Mathye, Matlhodi

2017-03-01

This study investigated passive neutralization of acid mine drainage using basic oxygen furnace slag as neutralization material over 90 days, with monitoring of the parameters' quality and assessment of their removal kinetics. The quality was observed to significantly improve over time with most parameters removed from the influent during the first 10 days. In this regard, removal of acidity, Fe(II), Mn, Co, Ni and Zn was characterized by fast kinetics while removal kinetics for Mg and SO 4 2- were observed to proceed slowly. The fast removal kinetics of acidity was attributed to fast release of alkalinity from slag minerals under mildly acidic conditions of the influent water. The removal of acidity through generation of alkalinity from the passive treatment system was also observed to generally govern the removal of metallic parameters through hydroxide formation, with overall percentage removals of 88-100% achieved. The removal kinetics for SO 4 2- was modelled using two approaches, yielding rate constant values of 1.56 and 1.53 L/(day mol) respectively, thereby confirming authenticity of SO 4 2- removal kinetics experimental data. The study findings provide insights into better understanding of the potential use of slags and their limitations, particularly in mine closure, as part of addressing this challenge in South Africa.

Detecting and removing multiplicative spatial bias in high-throughput screening technologies.

PubMed

Caraus, Iurie; Mazoure, Bogdan; Nadon, Robert; Makarenkov, Vladimir

2017-10-15

Considerable attention has been paid recently to improve data quality in high-throughput screening (HTS) and high-content screening (HCS) technologies widely used in drug development and chemical toxicity research. However, several environmentally- and procedurally-induced spatial biases in experimental HTS and HCS screens decrease measurement accuracy, leading to increased numbers of false positives and false negatives in hit selection. Although effective bias correction methods and software have been developed over the past decades, almost all of these tools have been designed to reduce the effect of additive bias only. Here, we address the case of multiplicative spatial bias. We introduce three new statistical methods meant to reduce multiplicative spatial bias in screening technologies. We assess the performance of the methods with synthetic and real data affected by multiplicative spatial bias, including comparisons with current bias correction methods. We also describe a wider data correction protocol that integrates methods for removing both assay and plate-specific spatial biases, which can be either additive or multiplicative. The methods for removing multiplicative spatial bias and the data correction protocol are effective in detecting and cleaning experimental data generated by screening technologies. As our protocol is of a general nature, it can be used by researchers analyzing current or next-generation high-throughput screens. The AssayCorrector program, implemented in R, is available on CRAN. makarenkov.vladimir@uqam.ca. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Adsorption Study on Moringa Oleifera Seeds and Musa Cavendish as Natural Water Purification Agents for Removal of Lead, Nickel and Cadmium from Drinking Water

NASA Astrophysics Data System (ADS)

Aziz, N. A. A.; Jayasuriya, N.; Fan, L.

2016-07-01

The effectiveness of plant based materials Moringa oleifera (Moringa) seeds and Musa cavendish (banana peel) for removing heavy metals namely lead (Pb), nickel (Ni) and cadmium (Cd) from contaminated groundwater was studied. Tests were carried out with individual and combined biomass at neutral pH condition on synthetic groundwater samples. The optimum biomass doses were determined as 200 mg/L for single biomass and 400 mg/L (in the ratio of 200 mg/L: 200 mg/L) for combined biomasses and used for adsorption isotherm studies with contact time of 30 minutes. Results showed that combined biomasses was able to met the Pb, Ni and Cd WHO standards from higher Pb, Ni and Cd initial concentrations which were up to 40 µg/L, 50 µg/L 9 µg/L, respectively compared to individual biomass of Moringa seed and banana peel. Moringa seeds exhibited the highest removal of Pb (81%) while the combined biomasses was most effective in removing Ni (74%) and Cd (97%) over wider their initial concentration ranges. The experimental data were linearized with Langmuir and Freundlich adsorption isotherm models. Freundlich model described the Pb adsorption better than the Langmuir model for all the tested biomasses. However, the Langmuir model fit better with the experimental data of Ni adsorption by Moringa seeds. Both models showed negligible differences in the coefficient of determination (R2) when applied for Ni and Cd adsorption on banana peel and combined biomasses, suggesting that there were multiple layers on the biomass interacting with the metals. Chemisorption is suggested to be involved in Pb adsorption for all tested biomasses as the value of nF calculated was lower than one. This type of adsorption could explain the phenomenon of different behavior of Pb removal and the higher Pb adsorption capacity (represented by KF values) compared to Ni and Cd. The study demonstrates that Moringa seeds, banana peel and their combination have the potential to be used as a natural alternative to the other water treatment agents for removing the Pb, Ni and Cd from drinking water.

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures

PubMed Central

Ossareh, A.; Rosentritt, M.; Kishen, A.

2018-01-01

Introduction: The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. Materials and Methods: The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test (P < 0.05). Results: Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group (P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group (P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups (R2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. Conclusions: The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF. PMID:29899632

Experimental tree removal in tallgrass prairie: variable responses of flora and fauna along a woody cover gradient.

PubMed

Alford, Aaron L; Hellgren, Eric C; Limb, Ryan; Engle, David M

2012-04-01

Woody plant encroachment is a worldwide phenomenon in grassland and savanna systems whose consequence is often the development of an alternate woodland state. Theoretically, an alternate state may be associated with changes in system state variables (e.g., species composition) or abiotic parameter shifts (e.g., nutrient availability). When state-variable changes are cumulative, such as in woody plant encroachment, the probability of parameter shifts increases as system feedbacks intensify over time. Using a Before-After Control-Impact (BACI) design, we studied eight pairs of grassland sites undergoing various levels of eastern redcedar (Juniperus virginiana) encroachment to determine whether responses of flora and fauna to experimental redcedar removal differed according to the level of pretreatment redcedar cover. In the first year after removal, herbaceous plant species diversity and evenness, woody plant evenness, and invertebrate family richness increased linearly with pretreatment redcedar cover, whereas increases in small-mammal diversity and evenness were described by logarithmic trends. In contrast, increases in woody plant diversity and total biomass of terrestrial invertebrates were accentuated at levels of higher pretreatment cover. Tree removal also shifted small-mammal species composition toward a more grassland-associated assemblage. During the second year postremoval, increases in herbaceous plant diversity followed a polynomial trend, but increases in most other metrics did not vary along the pretreatment cover gradient. These changes were accompanied by extremely high growing-season precipitation, which may have homogenized floral and faunal responses to removal. Our results demonstrate that tree removal increases important community metrics among grassland flora and fauna within two years, with some responses to removal being strongly influenced by the stage of initial encroachment and modulated by climatic variability. Our results underscore the importance of decisive management for reversing the effects of woody plant encroachment in imperiled grassland ecosystems.

Removal of fly-ash and dust particulate matters from syngas produced by gasification of coal by using a multi-stage dual-flow sieve plate wet scrubber.

PubMed

Kurella, Swamy; Meikap, Bhim Charan

2016-08-23

In this work, fly-ash water scrubbing experiments were conducted in a three-stage lab-scale dual-flow sieve plate scrubber to observe the performance of scrubber in fly-ash removal at different operating conditions by varying the liquid rate, gas rate and inlet fly-ash loading. The percentage of fly-ash removal efficiency increases with increase in inlet fly-ash loading, gas flow rate and liquid flow rate, and height of the scrubber; 98.55% maximum percentage of fly-ash removal efficiency (ηFA) is achieved at 19.36 × 10(-4) Nm(3)/s gas flow rate (QG) and 48.183 × 10(-6) m(3)/s liquid flow rate (QL) at 25 × 10(-3) kg/Nm(3) inlet fly-ash loading (CFA,i). A model has also been developed for the prediction of fly-ash removal efficiency of the column using the experimental results. The predicted values calculated using the correlation matched well with the experimental results. Deviations observed between the experimental and the predicted values were less than 20%.

Appropriate drinking water treatment processes for organic micropollutants removal based on experimental and model studies - a multi-criteria analysis study.

PubMed

Sudhakaran, Sairam; Lattemann, Sabine; Amy, Gary L

2013-01-01

The presence of organic micropollutants (OMPs), pharmaceuticals and personal care products (PPCPs) in potable water is of great environmental and public health concern. OMPs are included in the priority list of contaminants in United States EPA and European framework directives. Advanced treatment processes such as reverse osmosis, nanofiltration, ozonation and adsorption are the usual industry-recommended processes for OMPs removal, however, natural systems, e.g., riverbank filtration and constructed wetlands, are also potentially efficient options for OMPs removal. In this study, a decision support system (DSS) based on multi-criteria analysis (MCA) was created to compare processes for OMPs removal under various criteria. Multi-criteria analysis (MCA), a transparent and reliable procedure, was adopted. Models were built for both experimental and predicted percent-removals for a range of OMPs reflecting different physicochemical properties. The experimental percent-removals for several processes (riverbank filtration (RBF), ozonation, advanced oxidation, adsorption, reverse osmosis, and nanofiltration) were considered. The predicted percent-removals were taken from validated quantitative structure activity relationship (QSAR) models. Analytical methods to detect OMPs in water are very laborious, thus a modeling approach such as QSAR is an attractive option. A survey among two groups of participants including academics (PhD students and post-doctoral research associates) and industry (managers and operators) representatives was conducted to assign weights for the following criteria: treatability, costs, technical considerations, sustainability and time. The process rankings varied depending on the contaminant species and personal preferences (weights). The results indicated that RBF and oxidation were preferable over adsorption and membranes processes. The results also suggest that the use of a hybrid treatment process, e.g., combining a natural system with an advanced treatment (oxidation) process, may provide benefits for OMPs removal. The proposed DSS can be used as a screening tool for experimental planning or a feasibility study preceding the main treatment system selection and design. It can also be considered as an aid in assessing a multi-barrier approach to remove OMPs. Copyright © 2012 Elsevier B.V. All rights reserved.

Principles of light energy management

NASA Astrophysics Data System (ADS)

Davis, N.

1994-03-01

Six methods used to minimize excess energy effects associated with lighting systems for plant growth chambers are reviewed in this report. The energy associated with wall transmission and chamber operating equipment and the experimental requirements, such as fresh air and internal equipment, are not considered here. Only the energy associated with providing and removing the energy for lighting is considered.

Principles of light energy management

NASA Technical Reports Server (NTRS)

Davis, N.

1994-01-01

Six methods used to minimize excess energy effects associated with lighting systems for plant growth chambers are reviewed in this report. The energy associated with wall transmission and chamber operating equipment and the experimental requirements, such as fresh air and internal equipment, are not considered here. Only the energy associated with providing and removing the energy for lighting is considered.

SCALE-UP OF RAPID SMALL-SCALE ADSORPTION TESTS TO FIELD-SCALE ADSORBERS: THEORETICAL BASIS AND EXPERIMENTAL RESULTS FOR A CONSTANT DIFFUSIVITY

EPA Science Inventory

Granular activated carbon (GAC) is an effective treatment technique for the removal of some toxic organics from drinking water or wastewater, however, it can be a relatively expensive process, especially if it is designed improperly. A rapid method for the design of large-scale f...

Does Technology Integration "Work" when Key Barriers Are Removed?

ERIC Educational Resources Information Center

Lowther, Deborah L.; Inan, Fethi A.; Strahl, J. Daniel; Ross, Steven M.

2008-01-01

The effectiveness of Tennessee EdTech Launch (TnETL), a statewide technology program designed to meet the No Child Left Behind (NCLB) mandate, was investigated in this matched treatment-control quasi-experimental study. The goal of the program was to provide full-time, on-site technology coaches to prepare teachers to create lessons that engage…

Stooped postures are modified by pretask walking in a simulated weed-pulling task.

PubMed

Hudson, D S; Copeland, J L; Hepburn, C G; Doan, J B

2014-01-01

Seasonal agricultural workers are hired in some sectors for intermittent manual weed removal, a stoop and grasp harvesting task likely similar to those associated with the high prevalence of musculoskeletal disorders in agriculture. Evaluation of this task in an experimental situation would be useful for identifying and controlling musculoskeletal injury risks, presuming a valid experimental model of the task can be created. The purpose of the present study was to examine how a relevant work-related task, namely prolonged walking, altered the biomechanics of manual weed removal in a laboratory setting. Preliminary field assessments informed the development and analysis of a simulated manual weed removal with two separate conditions: not primed, where 11 participants (4 female, mean age 21.6 years) manually removed a simulated weed six times, and primed, where 23 participants (13 female, mean age 22.1 years) walked 1600 m prior to manually removing the same simulated weed six successive times. Segment end point markers and experimental motion capture were used to determine hip, knee, and ankle angles, as well as toe-target proximity, during weed removal. Significant differences between primed and not primed participants were found for angular displacement at the ankle (t(32) = 5.08, P < .001) and toe-target proximity (t(32) = 2.78, P = .008), where primed participants had increased ankle flexion and a greater distance to the weed, leading to decreased trunk flexion during the harvesting task. These findings suggest that priming can positively influence whole-body postures for manual weed removal.

Experimental investigation on cleaning of corroded ancient coins using a Nd:YAG laser

NASA Astrophysics Data System (ADS)

Zhu, Huazhong; Lu, Jian; Ni, Xiaowu; Shen, Zhonghua

2017-05-01

The objective of the work reported is to study experimentally on the removal of corrosion layer from the ancient coins using laser beam as the conservation tool. With the use of Q-switched Nd:YAG laser radiation at 1064 nm, dry laser cleaning, steam laser cleaning and chemical-assisted laser cleaning were used to find out a more suitable and efficient laser treatment for corrosion removal. Cleaning tests were performed on ancient Chinese coins. Experimental results shows that the dry laser cleaning was not successful at removing all types of corrosion crust. It was possible to remove the outer thicker layer of the corrosion products (typically known as patina), but failed on the thinner layer of cuprite. The steam laser cleaning could decrease the initial removal threshold and improve the removal efficiency especially for the oxidation with powdery structure. As for chemical-assisted laser treatment, the cleaning results demonstrate that the combination of laser and chemical reagent could provide a considerable improvement in corrosion removal compared with the conventional laser treatments. Most of the corrosion contaminant was stripped, even the cuprite layer. Moreover, no secondary pollution was formed on the cleaned surface. X-ray fluorescence was applied to determine the variation of composition of surface layer and bulk metal before and after the coins cleaned. It shows that all of the three laser treatments were efficient to reduce the chlorine concentration on the surface of the coins more than 75%.

An investigation of the treatment of particulate matter from gasoline engine exhaust using non-thermal plasma.

PubMed

Ye, Dan; Gao, Dengshan; Yu, Gang; Shen, Xianglin; Gu, Fan

2005-12-09

A plasma reactor with catalysts was used to treat exhaust gas from a gasoline engine in order to decrease particulate matter (PM) emissions. The effect of non-thermal plasma (NTP) of the dielectric discharges on the removal of PM from the exhaust gas was investigated experimentally. The removal efficiency of PM was based on the concentration difference in PM for particle diameters ranging from 0.3 to 5.0 microm as measured by a particle counter. Several factors affecting PM conversion, including the density of plasma energy, reaction temperature, flow rate of exhaust gas, were investigated in the experiment. The results indicate that PM removal efficiency ranged approximately from 25 to 57% and increased with increasing energy input in the reactor, reaction temperature and residence time of the exhaust gas in the reactor. Enhanced removal of the PM was achieved by filling the discharge gap of the reactor with Cu-ZSM-5 catalyst pellets. In addition, the removal of unburned hydrocarbons was studied. Finally, available approaches for PM conversion were analyzed involving the interactions between discharge and catalytic reactions.

Stabilized chitosan/Fe(0)-nanoparticle beads to remove heavy metals from polluted sediments.

PubMed

Liu, T; Sun, Y; Wang, Z L

2016-01-01

Sediment contamination by heavy metals has become a widespread problem that can affect the normal behaviors of rivers and lakes. After chitosan/Fe(0)-nanoparticles (CS-NZVI) beads were cross-linked with glutaraldehyde (GLA), their mechanical strength, stability and separation efficiency from the sediment were obviously improved. Moreover, the average aperture size of GLA-CS-NZVI beads was 20.6 μm and NZVI particles were nearly spherical in shape with a mean diameter of 40.2 nm. In addition, the pH showed an insignificant effect on the removal rates from the sediment. Due to the dissolution of metals species into aqueous solutions as an introduction of the salt, the removal rates of all heavy metals from the sediment were increased with an increase of the salinity. The competitive adsorption of heavy metals between the sediment particles and GLA-CS-NZVI beads became stronger as the sediment particles became smaller, leading to decreased removal rates. Therefore, the removal efficiency could be enhanced by optimizing experimental conditions and choosing appropriate materials for the target contaminants.

Removal of Arsenic (V) from Aqueous Solutions Using Chitosan-Red Scoria and Chitosan-Pumice Blends.

PubMed

Asere, Tsegaye Girma; Mincke, Stein; De Clercq, Jeriffa; Verbeken, Kim; Tessema, Dejene A; Fufa, Fekadu; Stevens, Christian V; Du Laing, Gijs

2017-08-09

In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch-Rs) and chitosan: pumice (Ch-Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm ( R ² > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.

Removal of aluminum from drinking water treatment sludge using vacuum electrokinetic technology.

PubMed

Xu, Hang; Ding, Mingmei; Shen, Kunlun; Cui, Jianfeng; Chen, Wei

2017-04-01

A vacuum electrokinetic apparatus was operated at a municipal water supply plant in Wuxi, China to study the removal of aluminum from the plant's drinking water treatment sludge, high in trivalent aluminum content. The effect of several experimental variables (initial pH, potential gradient, and zone in the sludge tank) and the trivalent aluminum removal mechanism were analyzed. The speciation of trivalent aluminum mainly depends on the initial pH of drinking water treatment sludge, and more fractions of trivalent aluminum were migrated at pH 4 than at higher or lower pH. The application of high voltage can enhance the removal efficiency of aluminum. A three-dimensional electric field analysis explained the difference in the removal efficiency at different zones in the sludge tank. In view of energy consumption, when the initial pH was 4 and a potential gradient of 2 V cm -1 was applied, achieving a final aluminum concentration of 30 g kg -1 after 120 h. The specific energy consumption was 11.7 kWh kg -1 of Al removed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Treatment of swine wastewater in continuous activated sludge systems under different dissolved oxygen conditions: Reactor operation and evaluation using modelling.

PubMed

Waki, Miyoko; Yasuda, Tomoko; Fukumoto, Yasuyuki; Béline, Fabrice; Magrí, Albert

2018-02-01

Swine wastewater was treated in two continuously aerated activated sludge (AS) systems at high (AS1: 1.7-2.6 mg/L) and low (AS2: 0.04-0.08 mg/L) dissolved oxygen (DO), and at three temperatures (10, 20, and 30 °C). Biochemical oxygen demand (BOD) removal was >94.8%. Meanwhile, total nitrogen (N) removal was significantly higher in AS2, at 64, 89, and 88%, than in AS1, at 12, 24, and 46%, for 10, 20, and 30 °C, respectively. The experimental data were considered in a simulation study using an AS model for BOD and N removal, which also included nitrite, free ammonia, free nitrous acid, and temperature. Simulations at high-DO showed that ammonium was partly oxidized into nitrate but not removed, whereas at low-DO ammonium was removed mainly through the nitrite shortcut in simultaneous nitrification-denitrification. This study demonstrates that treatment at low-DO is an effective method for removing N, and modelling a helpful tool for its optimization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Endonasal Skull Base Tumor Removal Using Concentric Tube Continuum Robots: A Phantom Study.

PubMed

Swaney, Philip J; Gilbert, Hunter B; Webster, Robert J; Russell, Paul T; Weaver, Kyle D

2015-03-01

Objectives The purpose of this study is to experimentally evaluate the use of concentric tube continuum robots in endonasal skull base tumor removal. This new type of surgical robot offers many advantages over existing straight and rigid surgical tools including added dexterity, the ability to scale movements, and the ability to rotate the end effector while leaving the robot fixed in space. In this study, a concentric tube continuum robot was used to remove simulated pituitary tumors from a skull phantom. Design The robot was teleoperated by experienced skull base surgeons to remove a phantom pituitary tumor within a skull. Percentage resection was measured by weight. Resection duration was timed. Setting Academic research laboratory. Main Outcome Measures Percentage removal of tumor material and procedure duration. Results Average removal percentage of 79.8 ± 5.9% and average time to complete procedure of 12.5 ± 4.1 minutes (n = 20). Conclusions The robotic system presented here for use in endonasal skull base surgery shows promise in improving the dexterity, tool motion, and end effector capabilities currently available with straight and rigid tools while remaining an effective tool for resecting the tumor.

Parabens abatement from surface waters by electrochemical advanced oxidation with boron doped diamond anodes.

PubMed

Domínguez, Joaquín R; Muñoz-Peña, Maria J; González, Teresa; Palo, Patricia; Cuerda-Correa, Eduardo M

2016-10-01

The removal efficiency of four commonly-used parabens by electrochemical advanced oxidation with boron-doped diamond anodes in two different aqueous matrices, namely ultrapure water and surface water from the Guadiana River, has been analyzed. Response surface methodology and a factorial, composite, central, orthogonal, and rotatable (FCCOR) statistical design of experiments have been used to optimize the process. The experimental results clearly show that the initial concentration of pollutants is the factor that influences the removal efficiency in a more remarkable manner in both aqueous matrices. As a rule, as the initial concentration of parabens increases, the removal efficiency decreases. The current density also affects the removal efficiency in a statistically significant manner in both aqueous matrices. In the water river aqueous matrix, a noticeable synergistic effect on the removal efficiency has been observed, probably due to the presence of chloride ions that increase the conductivity of the solution and contribute to the generation of strong secondary oxidant species such as chlorine or HClO/ClO - . The use of a statistical design of experiments made it possible to determine the optimal conditions necessary to achieve total removal of the four parabens in ultrapure and river water aqueous matrices.

Removal of Arsenic (V) from Aqueous Solutions Using Chitosan–Red Scoria and Chitosan–Pumice Blends

PubMed Central

Asere, Tsegaye Girma; Mincke, Stein; De Clercq, Jeriffa; Verbeken, Kim; Tessema, Dejene A.; Fufa, Fekadu; Stevens, Christian V.; Du Laing, Gijs

2017-01-01

In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch–Rs) and chitosan: pumice (Ch–Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm (R2 > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water. PMID:28792443

The behavior of antibiotic resistance genes and arsenic influenced by biochar during different manure composting.

PubMed

Cui, Erping; Wu, Ying; Jiao, Yanan; Zuo, Yiru; Rensing, Christopher; Chen, Hong

2017-06-01

The effect of two different biochar types, rice straw biochar (RSB) and mushroom biochar (MB), on chicken manure composting was previously examined by monitoring the fate of antibiotic resistance genes (ARGs) and arsenic. The behavior of ARGs and arsenic in other kinds of manure composting with the same biochar types had not been examined. In this study, we added either RSB or MB to pig and duck manure composts to study the behavior of ARGs (tet genes, sul genes, and chloramphenicol resistance genes) and arsenic under the same experimental condition. The results showed that the average removal values of selected ARGs were respectively 2.56 and 2.09 log units in duck and pig manure compost without the addition of biochar. The effect of biochar addition on the average removal value of ARGs depended on the type of biochar and manure. For instance, in pig manure compost, MB addition increased the average removal value of ARGs, while RSB addition decreased. And both biochar additions had a negative influence on the average removal value of ARGs in duck manure compost. Analytical results also demonstrated that MB addition reduced total arsenic and the percentage of bioavailable arsenic more than RSB.

Lead (II) removal from natural soils by enhanced electrokinetic remediation.

PubMed

Altin, Ahmet; Degirmenci, Mustafa

2005-01-20

Electrokinetic remediation is a very effective method to remove metal from fine-grained soils having low adsorption and buffering capacity. However, remediation of soil having high alkali and adsorption capacity via the electrokinetic method is a very difficult process. Therefore, enhancement techniques are required for use in these soil types. In this study, the effect of the presence of minerals having high alkali and cation exchange capacity in natural soil polluted with lead (II) was investigated by means of the efficiency of electrokinetic remediation method. Natural soil samples containing clinoptilolite, gypsum and calcite minerals were used in experimental studies. Moreover, a sample containing kaolinite minerals was studied to compare with the results obtained from other samples. Best results for soils bearing alkali and high sorption capacity minerals were obtained upon addition of 3 mol AcH and application of 20 V constant potential after a remediation period of 220 h. In these test conditions, lead (II) removal efficiencies for these samples varied between 60% and 70% up to 0.55 normalized distance. Under the same conditions, removal efficiencies in kaolinite sample varied between 50% and 95% up to 0.9 normalized distance.

Extracorporeal CO2 removal: Technical and physiological fundaments and principal indications.

PubMed

Romay, E; Ferrer, R

2016-01-01

In recent years, technological improvements have reduced the complexity of extracorporeal membrane oxygenation devices. This have enabled the development of specific devices for the extracorporeal removal of CO2. These devices have a simpler configuration than extracorporeal membrane oxygenation devices and uses lower blood flows which could reduce the potential complications. Experimental studies have demonstrated the feasibility, efficacy and safety of extracorporeal removal of CO2 and some of its effects in humans. This technique was initially conceived as an adjunct therapy in patients with severe acute respiratory distress syndrome, as a tool to optimize protective ventilation. More recently, the use of this technique has allowed the emergence of a relatively new concept called "tra-protective ventilation"whose effects are still to be determined. In addition, the extracorporeal removal of CO2 has been used in patients with exacerbated hypercapnic respiratory failure with promising results. In this review we will describe the physiological and technical fundamentals of this therapy and its variants as well as an overview of the available clinical evidence, focused on its current potential. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Evaluation of Cajanus cajan (pigeon pea) for phytoremediation of landfill leachate containing chromium and lead.

PubMed

Jerez Ch, José A; Romero, Rosaura M

2016-11-01

Landfill leachates containing heavy metals are important contaminants and a matter of great concern due to the effect that they might have on ecosystems. We evaluated the use of Cajanus cajan to remove chromium and lead from landfill leachates. Eight-week-old plants were submitted to varied tests to select the experimental conditions. Water assays with a solution (pH 6) containing leachate (25% v/v) were selected; the metals were added as potassium dichromate and lead (II) nitrate salts. Soil matrices that contained leachate (30% v/v) up to field capacity were used. For both water and soil assays, the metal concentrations were 10 mg kg(-1). C. cajan proved able to remove 49% of chromium and 36% of lead, both from dilute leachate. The plants also removed 34.7% of chromium from irrigated soil, but were unable to decrease the lead content. Removal of nitrogen from landfill leachate was also tested, resulting in elimination of 85% of ammonia and 70% of combined nitrite/nitrate species. The results indicate that C. cajan might be an effective candidate for the rhizofiltration of leachates containing chromium and lead, and nitrogen in large concentrations.

Removal rate model for magnetorheological finishing of glass.

PubMed

Degroote, Jessica E; Marino, Anne E; Wilson, John P; Bishop, Amy L; Lambropoulos, John C; Jacobs, Stephen D

2007-11-10

Magnetorheological finishing (MRF) is a deterministic subaperture polishing process. The process uses a magnetorheological (MR) fluid that consists of micrometer-sized, spherical, magnetic carbonyl iron (CI) particles, nonmagnetic polishing abrasives, water, and stabilizers. Material removal occurs when the CI and nonmagnetic polishing abrasives shear material off the surface being polished. We introduce a new MRF material removal rate model for glass. This model contains terms for the near surface mechanical properties of glass, drag force, polishing abrasive size and concentration, chemical durability of the glass, MR fluid pH, and the glass composition. We introduce quantitative chemical predictors for the first time, to the best of our knowledge, into an MRF removal rate model. We validate individual terms in our model separately and then combine all of the terms to show the whole MRF material removal model compared with experimental data. All of our experimental data were obtained using nanodiamond MR fluids and a set of six optical glasses.

Spray scrubbing of particulate-laden SO(2) using a critical flow atomizer.

PubMed

Bandyopadhyay, Amitava; Biswas, Manindra Nath

2008-08-01

The performance of a spray tower using an energy efficient two-phase critical flow atomizer on the scrubbing of particulate-laden SO(2) using water and dilute NaOH is reported in this article. Experimentation revealed that SO(2) removal was enhanced due to presence of particles (fly-ash) and almost 100% removal efficiency was achieved in water scrubbing. The removal efficiency is elucidated in reference to atomizing air pressure, droplet diameter and droplet velocity besides other pertinent variables of the system studied. The presence of fly-ash particles improved the removal efficiency to about 20% within the range of variables studied. Empirical and semi-empirical correlations were developed for predicting the removal efficiency in water and dilute NaOH respectively. Predicted data fitted excellently well with experimental values. The performance of the spray tower is compared with the performances of existing systems and very encouraging results are obtained.

The Missing Treatment Design Element: Continuity of Treatment When Multiple Postobservations Are Used in Time-Series and Repeated Measures Study Designs

ERIC Educational Resources Information Center

Barnette, J. Jackson; Wallis, Anne Baber

2005-01-01

We rely a great deal on the schematic descriptions that represent experimental and quasi-experimental design arrangements, as well as the discussions of threats to validity associated with these, provided by Campbell and his associates: Stanley, Cook, and Shadish. Some of these designs include descriptions of treatments removed, removed and then…

Effect of Ca2+ Efflux Pathway Distribution and Exogenous Ca2+ Buffers on Intracellular Ca2+ Dynamics in the Rat Ventricular Myocyte: A Simulation Study

PubMed Central

Šimurda, Jiří; Orchard, Clive H.

2014-01-01

We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca2+ efflux pathways (SERCA, Na+/Ca2+ exchange, and sarcolemmal Ca2+ ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca2+ buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca2+ in the dyad and bulk cytoplasm, on cellular Ca2+ cycling. Increasing the dyadic fraction of a particular Ca2+ efflux pathway increases the amount of Ca2+ removed by that pathway, with corresponding changes in Ca2+ efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca2+ removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca2+-dependent inactivation of the L-type Ca2+ current, resulted from the buffers acting as slow and fast “shuttles,” respectively, removing Ca2+ from the dyadic space. The data suggest that complex changes in dyadic Ca2+ and cellular Ca2+ cycling occur as a result of changes in the location of Ca2+ removal pathways or the presence of exogenous Ca2+ buffers, although changing the distribution of Ca2+ efflux pathways has relatively small effects on the systolic Ca2+ transient. PMID:24971358

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.

Boron removal by electrocoagulation and recovery.

PubMed

Isa, Mohamed Hasnain; Ezechi, Ezerie Henry; Ahmed, Zubair; Magram, Saleh Faraj; Kutty, Shamsul Rahman Mohamed

2014-03-15

This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Experimental study on Hg0 removal from flue gas over columnar MnOx-CeO2/activated coke

NASA Astrophysics Data System (ADS)

Xie, Yine; Li, Caiting; Zhao, Lingkui; Zhang, Jie; Zeng, Guangming; Zhang, Xunan; Zhang, Wei; Tao, Shasha

2015-04-01

Mn-Ce mixed oxides supported on commercial columnar activated coke (MnCe/AC) were employed to remove elemental mercury (Hg0) at low temperatures (100-250 °C) without the assistance of HCl in flue gas. The samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Effects of some factors, including Mn-Ce loading values, active component, reaction temperatures and flue gas components (O2, SO2, NO, H2O), on Hg0 removal efficiency were investigated. Results indicated that the optimal Mn-Ce loading value and reaction temperature were 6% and 190 °C, respectively. Considerable high Hg0 removal efficiency (>90%) can be obtained over MnCe6/AC under both N2/O2 atmosphere and simulated flue gas atmosphere at 190 °C. Besides, it was observed that O2 and NO exerted a promotional effect on Hg0 removal, H2O exhibited a suppressive effect, and SO2 hindered Hg0 removal seriously when in the absence of O2. Furthermore, the XPS spectra of Hg 4f and Hg-TPD results showed that the captured mercury were existed as Hg0 and HgO on the MnCe6/AC, and HgO was the major species, which illustrated that adsorption and catalytic oxidation process were included for Hg0 removal over MnCe6/AC, and catalytic oxidation played the critical role. What's more, both lattice oxygen and chemisorbed oxygen or OH groups on MnCe6/AC contributed to Hg0 oxidation. MnCe6/AC, which exhibited excellent performance on Hg0 removal in the absence of HCl, appeared to be promising in industrial application, especially for low-rank coal fired flue gas.

Bacterial Reduction after Gutta-Percha Removal with Single vs. Multiple Instrument Systems.

PubMed

Xavier, Felipe; Nevares, Giselle; Gominho, Luciana; Rodrigues, Renata; Cassimiro, Marcely; Romeiro, Kaline; Albuquerque, Diana

2018-01-01

The aim of this study was to evaluate the effectiveness of a reciprocating single-instrument system (Reciproc-REC) compared with combined continuously rotating multiple-instrument systems [D-Race (DR) and BioRace (BR)] in reducing Enterococcus faecalis (E.f.) after gutta-percha removal. Forty-six extracted human maxillary incisors were prepared and contaminated with E.f. strain (ATCC 29212) for 30 days. The samples were obturated and randomly divided into two experimental groups for gutta-percha removal ( n =23): a REC group (R50) and a DR/BR group (DR1, DR2 and BR6). A standardized irrigation with 0.9% saline solution was performed. Root canal samples were taken with paper points before (S1) and after (S2) the removal of gutta-percha to establish bacterial quantification by culture. The time required for gutta-percha removal was also recorded. Positive and negative control groups ( n =6) were used to test bacterial viability and control asepsis, respectively. Data were analysed using t -Student and one-way ANOVA tests (5% margin of error). The mean percentage of bacterial reduction was significantly higher in DR/BR group (84.2%) than in REC group (72.3%) ( P <0.05). The mean time for obturation removal was 74.00 sec in REC group and 107.53 sec in DR/BR group ( P <0.05). The combined continuously rotating multiple-instrument system was more effective in reducing bacteria after the removal of gutta-percha than the single-instrument system. None of the tested systems was able to completely eliminate root canal infection after gutta-percha removal. Thus, additional techniques should be considered.

Impulse Noise Cancellation of Medical Images Using Wavelet Networks and Median Filters

PubMed Central

Sadri, Amir Reza; Zekri, Maryam; Sadri, Saeid; Gheissari, Niloofar

2012-01-01

This paper presents a new two-stage approach to impulse noise removal for medical images based on wavelet network (WN). The first step is noise detection, in which the so-called gray-level difference and average background difference are considered as the inputs of a WN. Wavelet Network is used as a preprocessing for the second stage. The second step is removing impulse noise with a median filter. The wavelet network presented here is a fixed one without learning. Experimental results show that our method acts on impulse noise effectively, and at the same time preserves chromaticity and image details very well. PMID:23493998

II. Electrodeposition/removal of nickel in a spouted electrochemical reactor.

PubMed

Grimshaw, Pengpeng; Calo, Joseph M; Shirvanian, Pezhman A; Hradil, George

2011-08-17

An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well.

Effects of coolant parameters on steady state temperature distribution in phospheric-acid fuel cell electrode

NASA Technical Reports Server (NTRS)

Alkasab, K. A.; Abdul-Aziz, A.

1991-01-01

The influence of thermophysical properties and flow rate on the steady-state temperature distribution in a phosphoric-acid fuel cell electrode plate was experimentally investigated. An experimental setup that simulates the operating conditions prevailing in a phosphoric-acid fuel cell stack was used. The fuel cell cooling system utilized three types of coolants to remove excess heat generated in the cell electrode and to maintain a reasonably uniform temperature distribution in the electrode plate. The coolants used were water, engine oil, and air. These coolants were circulated at Reynolds number ranging from 1165 to 6165 for water; 3070 to 6864 for air; and 15 to 79 for oil. Experimental results are presented.

Optimization of Fe2+ Removal from Coal Mine Wastewater using Activated Biochar of Colocasia esculenta.

PubMed

Banerjee, Soumya; LaminKa-Ot, Augustine; Joshi, S R; Mandal, Tamal; Halder, Gopinath

2017-09-01

  The present study investigates the sorptive removal of Fe2+ from simulated coal mine waste water using steam activated biochar (SABC) developed from the roots of Colocasia esculenta. The process was optimized by response surface methodology (RSM) under the influence of pH, temperature, adsorbent dosage and contact time at a constant shaking speed of 180 rpm with an initial concentration of 3 mg/L. The uptake performance of the biosorbent was assessed following a 24 full factorial experimental matrix developed by central composite design approach. Adsorbent was characterised by SEM, EDAX, XRD and B.E.T surface area analyzer. Maximum removal of 72.96% of Fe2+ was observed at pH 7.75, temperature 37.5 °C, adsorbent dosage 1.5 g/L for a time period of 180 mins. The study suggested that SABC prepared from roots of Colocasia esculenta could be used as an efficient and cost effective sorbent for removal of Fe2+ from coal mine wastewater.

Utilization of Corn Cob and TiO2 Photocatalyst Thin Films for Dyes Removal.

PubMed

Gan, Hui-Yee; Leow, Li-Eau; Ong, Siew-Teng

2017-01-01

The effectiveness of using TiO2 and corn cob films to remove Malachite Green oxalate (MG) and Acid Yellow 17 (AY 17) from binary dye solution was studied. The immobilization method in this study can avoid the filtration step which is not suited for practical applications. Batch studies were performed under different experimental conditions and the parameters studied involved initial pH of dye solution, initial dye concentration and contact time and reusability. The equilibrium data of MG and AY 17 conform to Freundlich and Langmuir isotherm model, respectively. The percentage removal of MG remained high after four sorption cycles, however for AY 17, a greater reduction was observed. The removal of both dyes were optimized and modeled via Plackett- Burman design (PB) and Response Surface Methodology (RSM). IR spectrum and surface conditions analyses were carried out using fourier-transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM) and atomic force microscope (AFM), respectively.

Low-cost adsorbent prepared from sewage sludge and corn stalk for the removal of COD in leachate.

PubMed

He, Ying; Liao, Xiaofeng; Liao, Li; Shu, Wei

2014-01-01

Sewage sludge (SS) with corn stalk (CS) was used to prepare SS-based activated carbon (SAC) by pyrolysis with ZnCl2. The effects of mixing ratio on surface area and pore size distribution, elemental composition, surface chemistry, and morphology were investigated. The results demonstrated that the addition of CS into SS samples improved the surface area (from 92 to 902 m(2)/g) and the microporosity (from 1.2 to 4.1%) of the adsorbents and, therefore, enhancing the adsorption performance. The removal of leachate chemical oxygen demand (COD) was also determined. It was found that the COD removal rate reached 85% at pH 4 with the SAC (90 wt% CS) dosage of 2% (g/mL) and an adsorption time of 40 min. The adsorption experimental data were fitted by both Langmuir and Freundlich adsorption isotherms. Long-chain alkanes and refractory organics were found in raw leachate, but could be removed by SAC largely.

An empirical model for parameters affecting energy consumption in boron removal from boron-containing wastewaters by electrocoagulation.

PubMed

Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar

2007-06-01

In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0 mA/cm(2), initial boron concentration 100mg/L and solution temperature 293 K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following; [formula in text]. Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.

Comparison of ultrasonic with stirrer performance for removal of sunset yellow (SY) by activated carbon prepared from wood of orange tree: artificial neural network modeling.

PubMed

Ghaedi, A M; Ghaedi, M; Karami, P

2015-03-05

The present work focused on the removal of sunset yellow (SY) dye from aqueous solution by ultrasound-assisted adsorption and stirrer by activated carbon prepared from wood of an orange tree. Also, the artificial neural network (ANN) model was used for predicting removal (%) of SY dye based on experimental data. In this study a green approach was described for the synthesis of activated carbon prepared from wood of an orange tree and usability of it for the removal of sunset yellow. This material was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The impact of variables, including initial dye concentration (mg/L), pH, adsorbent dosage (g), sonication time (min) and temperature (°C) on SY removal were studied. Fitting the experimental equilibrium data of different isotherm models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models display the suitability and applicability of the Langmuir model. Analysis of experimental adsorption data by different kinetic models including pseudo-first and second order, Elovich and intraparticle diffusion models indicate the applicability of the second-order equation model. The adsorbent (0.5g) is applicable for successful removal of SY (>98%) in short time (10min) under ultrasound condition. Copyright © 2014 Elsevier B.V. All rights reserved.

Can we remove iodine-131 from tap water in Japan by boiling? - Experimental testing in response to the Fukushima Daiichi Nuclear Power Plant accident.

PubMed

Tagami, K; Uchida, S

2011-08-01

Iodine-131 concentrations in tap water higher than 100 BqL(-1) were reported by several local governments in Japan following the Fukushima Daiichi Nuclear Power Plant accident. Some individuals in the emergency-response community recommended the boiling of tap water to remove iodine-131. However, the tap water boiling tests in this study showed no iodine-131 loss from the tap water with either short-term boiling (1-10 min) or prolonged boiling (up to 30 min) resulting in up to 3-fold volume reductions. In this situation, boiling was shown to be not effective in removing iodine-131 from tap water; indeed even higher concentrations may result from the liquid-volume reduction accompanying this process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optimization of enhanced bioelectrical reactor with electricity from microbial fuel cells for groundwater nitrate removal.

PubMed

Liu, Ye; Zhang, Baogang; Tian, Caixing; Feng, Chuanping; Wang, Zhijun; Cheng, Ming; Hu, Weiwu

2016-01-01

Factors influencing the performance of a continual-flow bioelectrical reactor (BER) intensified by microbial fuel cells for groundwater nitrate removal, including nitrate load, carbon source and hydraulic retention time (HRT), were investigated and optimized by response surface methodology (RSM). With the target of maximum nitrate removal and minimum intermediates accumulation, nitrate load (for nitrogen) of 60.70 mg/L, chemical oxygen demand (COD) of 849.55 mg/L and HRT of 3.92 h for the BER were performed. COD was the dominant factor influencing performance of the system. Experimental results indicated the undistorted simulation and reliable optimized values. These demonstrate that RSM is an effective method to evaluate and optimize the nitrate-reducing performance of the present system and can guide mathematical models development to further promote its practical applications.

Light Field Imaging Based Accurate Image Specular Highlight Removal

PubMed Central

Wang, Haoqian; Xu, Chenxue; Wang, Xingzheng; Zhang, Yongbing; Peng, Bo

2016-01-01

Specular reflection removal is indispensable to many computer vision tasks. However, most existing methods fail or degrade in complex real scenarios for their individual drawbacks. Benefiting from the light field imaging technology, this paper proposes a novel and accurate approach to remove specularity and improve image quality. We first capture images with specularity by the light field camera (Lytro ILLUM). After accurately estimating the image depth, a simple and concise threshold strategy is adopted to cluster the specular pixels into “unsaturated” and “saturated” category. Finally, a color variance analysis of multiple views and a local color refinement are individually conducted on the two categories to recover diffuse color information. Experimental evaluation by comparison with existed methods based on our light field dataset together with Stanford light field archive verifies the effectiveness of our proposed algorithm. PMID:27253083

Treatment of textile wastewater by a hybrid electrocoagulation/nanofiltration process.

PubMed

Aouni, Anissa; Fersi, Cheïma; Ben Sik Ali, Mourad; Dhahbi, Mahmoud

2009-09-15

Untreated effluents from textile industries are usually highly coloured and contain a considerable amount of contaminants and pollutants. Stringent environmental regulation for the control of textile effluents is enforced in several countries. Previous studies showed that many techniques have been used for the treatment of textile wastewater, such as adsorption, biological treatment, oxidation, coagulation and/or flocculation, among them coagulation is one of the most commonly used techniques. Electrocoagulation is a process consisting in creating metallic hydroxide flocks within the wastewater by the electrodissolution of soluble anodes, usually made of iron or aluminium. This method has been practiced for most of the 20th century with limited success. In recent years, however, it started to regain importance with the progress of the electrochemical processes and the increase in environmental restrictions in effluent wastewater. This paper examines the use of electrocoagulation treatment process followed by nanofiltration process of a textile effluent sample. The electrocoagulation process was studied under several conditions such as various current densities and effect of experimental tense. Efficiencies of COD and turbidity reductions and colour removal were studied for each experiment. The electrochemical treatment was indented primarily to remove colour and COD of wastewater while nanofiltration was used to further improve the removal efficiency of the colour, COD, conductivity, alkalinity and total dissolved solids (TDS). The experimental results, throughout the present study, have indicated that electrocoagulation treatment followed by nanofiltration processes were very effective and were capable of elevating quality of the treated textile wastewater effluent.

Removal of pollutants with determination of power consumption from landfill leachate wastewater using an electrocoagulation process: optimization using response surface methodology (RSM)

NASA Astrophysics Data System (ADS)

Asaithambi, Perumal; Beyene, Dejene; Aziz, Abdul Raman Abdul; Alemayehu, Esayas

2018-05-01

Treatment of landfill leachate wastewater by electrocoagulation process using an aluminium electrode was investigated in a batch electrochemical cell reactor. Response surface methodology based on central composite design was used to optimize the operating parameters for the removal of % color and % total organic carbon (TOC) together with power consumption from landfill leachate. Effects of three important independent parameters such as current density ( X 1), inter-electrode distance ( X 2) and solution pH ( X 3) of the landfill leachate sample on the % color and % TOC removal with power consumption were investigated. A quadratic model was used to predict the % color and % TOC removal with power consumption in different experimental conditions. The significance of each independent variable was calculated by analysis of variance. In order to achieve the maximum % color and % TOC removal with minimum of power consumption, the optimum conditions were about current density ( X 1)—5.25 A/dm2, inter-electrode distance ( X 2)—1 cm and initial solution of effluent pH ( X 3)—7.83, with the yield of color removal of 74.57%, and TOC removal of 51.75% with the power consumption of 14.80 kWh/m3. Electrocoagulation process could be applied to remove pollutants from industrial effluents and wastewater.

Removal of Escherichia coli via low frequency electromagnetic field in riverbank filtration system.

NASA Astrophysics Data System (ADS)

Selamat, Rossitah; Abustan, Ismail; Rizal Arshad, Mohd; Mokhtar Kamal, Nurul Hana

2018-04-01

The removal of Escherichia coli (E. coli) via low frequency of electromagnetic field (LF-EMF) with different magnetic field was studied. LF-EMF is known as a high magnetic susceptibility method, which could affect E. coli growth without the usage of chemicals. The aim of this study was to investigate the removal of E. coli by using LF-EMF in water abstraction for the riverbank filtration (RBF) application. The effect of LF-EMF with the intensity of 2 to 10mT and 50Hz on coiled column of 1mm copper wire at 1 to 6 hours was assessed. The removal of E. coli after exposing to LF-EMF on the column model was measured using most probable number (MPN/100mL) and colonies forming unit (CFU/100mL) methods. Water flows into the column were varied up to 6 hours and with flowrate of 100 mL/min. Experimental results demonstrate that 100% of E. coli was removed at 8mT after 6 hours exposure. The magnetic field at 10mT removed 100% of E. coli after 4 hours exposure. The results obtained in this study proved that the LF-EMF was efficient in E. coli removal from RBF system. These finding indicated that the LF-EMF intensities and time of exposure can affect the removal of E. coli.

Sono assisted electrocoagulation process for the removal of pollutant from pulp and paper industry effluent.

PubMed

Asaithambi, P; Aziz, Abdul Raman Abdul; Sajjadi, Baharak; Daud, Wan Mohd Ashri Bin Wan

2017-02-01

In the present work, the efficiency of the sonication, electrocoagulation, and sono-electrocoagulation process for removal of pollutants from the industrial effluent of the pulp and paper industry was compared. The experimental results showed that the sono-electrocoagulation process yielded higher pollutant removal percentage compared to the sonication and electrocoagulation process alone. The effect of the operating parameters in the sono-electrocoagulation process such as electrolyte concentration (1-5 g/L), current density (1-5 A/dm 2 ), effluent pH (3-11), COD concentration (1500-6000 mg/L), inter-electrode distance (1-3 cm), and electrode combination (Fe and Al) on the color removal, COD removal, and power consumption were studied. The maximum color and COD removal percentages of 100 and 95 %, respectively, were obtained at the current density of 4 A/dm 2 , electrolyte concentration of 4 g/L, effluent pH of 7, COD concentration of 3000 mg/L, electrode combination of Fe/Fe, inter-electrode distance of 1 cm, and reaction time of 4 h, respectively. The color and COD removal percentages were analyzed by using an UV/Vis spectrophotometer and closed reflux method. The results showed that the sono-electrocoagulation process could be used as an efficient and environmental friendly technique for complete pollutant removal.

Efficacy of sonic and ultrasonic activation for removal of calcium hydroxide from mesial canals of mandibular molars: a microtomographic study.

PubMed

Wiseman, Anne; Cox, Timothy C; Paranjpe, Avina; Flake, Natasha M; Cohenca, Nestor; Johnson, James D

2011-02-01

The purpose of this study was to use micro-computed tomography (micro-CT) scanning to evaluate the efficacy of sonic and passive ultrasonic irrigation (PUI) on calcium hydroxide (Ca[OH](2)) removal and to measure the volume and percentage of Ca(OH)(2) remaining in the root canal system. The root canals of 46 extracted human mandibular molar teeth were prepared with rotary instruments and randomly assigned to two experimental groups (n = 40) as well as positive and negative controls (n = 6). In each experimental group, 20 teeth were assigned to each irrigation protocol, sonic or passive ultrasonic irrigation. All experimental teeth and the positive controls were filled with Ca(OH)(2), whereas the negative control teeth did not receive Ca(OH)(2). All teeth were scanned using micro-CT scanning to determine the dressing volume. After 7 days, the Ca(OH)(2) was removed in the experimental groups using rotary instrumentation only, and the teeth were again scanned using micro-CT scanning to calculate volume and percentage of Ca(OH)(2) removed. Positive control teeth were not subjected to rotary instrumentation. Experimental samples were then irrigated using either sonic or passive ultrasonic and the volume of remaining Ca(OH)(2) was calculated using micro-CT. Remnants of Ca(OH)(2) were found in all experimental groups. No Ca(OH)(2) was found in the negative controls, whereas a mean of 8.7 mm(3) of Ca(OH)(2) was recorded in the positive controls. Rotary plus passive ultrasonic irrigation removed significantly more Ca(OH)(2) (85.7%) than rotary plus sonic irrigation (71.5%) (p < 0.001). The combination of rotary instrumentation and passive ultrasonic activation for 3 periods of 20 seconds results in significantly lower amounts of Ca(OH)(2) remnants in the canal compared with sonic irrigation. Copyright © 2011. Published by Elsevier Inc.

Experimental design for the evaluation of struvite sedimentation obtained from an ammonium concentrated wastewater.

PubMed

Castro, Samuel Rodrigues; Araújo, Mahira Adna Cota; Lange, Liséte Celina

2013-01-01

Chemical precipitation of struvite as a technique of ammonium nitrogen (NH(4)-N) removal from concentrated wastewater has been shown to be an attractive alternative due to its high effectiveness, reaction rate, simplicity, environmental sustainability and, especially, the application potential of the generated solids for the fertilizer industry. The technique of experimental design has been used in order to identify and evaluate the optimum conditions of chemical precipitation reaction applied in a struvite sedimentation study. The preliminary tests were performed using synthetic effluent with a concentration equal to 500.0 mg N L(-1). The stoichiometric ratio Mg:NH(4):PO(4) equal to 1.5:1.0:1.25 and pH equal to 8.5 were taken to be the optimum conditions, where a NH(4)-N removal equal to 98.6% was achieved with only 10-min reaction time. This condition has been used to evaluate the struvite sedimentation from synthetic wastewaters, intending to check the optimum conditions achieved by the experimental design in different initial concentrations, 1,000 and 2,000 mg N L(-1). The results were typical of a good zonal sedimentation and can be used in the scale up the system.

Effect of impurities and post-experimental purification in SAD phasing with serial femtosecond crystallography data.

PubMed

Zhang, Tao; Gu, Yuanxin; Fan, Haifu

2016-06-01

In serial crystallography (SX) with either an X-ray free-electron laser (XFEL) or synchrotron radiation as the light source, huge numbers of micrometre-sized crystals are used in diffraction data collection. For a SAD experiment using a derivative with introduced heavy atoms, it is difficult to completely exclude crystals of the native protein from the sample. In this paper, simulations were performed to study how the inclusion of native crystals in the derivative sample could affect the result of SAD phasing and how the post-experimental purification proposed by Zhang et al. [(2015), Acta Cryst. D71, 2513-2518] could be used to remove the impurities. A gadolinium derivative of lysozyme and the corresponding native protein were used in the test. Serial femtosecond crystallography (SFX) diffraction snapshots were generated by CrystFEL. SHELXC/D, Phaser, DM, ARP/wARP and REFMAC were used for automatic structure solution. It is shown that a small amount of impurities (snapshots from native crystals) in the set of derivative snapshots can strongly affect the SAD phasing results. On the other hand, post-experimental purification can efficiently remove the impurities, leading to results similar to those from a pure sample.

Edge geometry effects on resonance response of electroplated cylindrical Ni/PZT/Ni magnetoelectric composites

NASA Astrophysics Data System (ADS)

Yakubov, Vladislav; Xu, Lirong; Volinsky, Alex A.; Qiao, Lijie; Pan, De'an

2017-08-01

Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME) composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.

Space debris detection in optical image sequences.

PubMed

Xi, Jiangbo; Wen, Desheng; Ersoy, Okan K; Yi, Hongwei; Yao, Dalei; Song, Zongxi; Xi, Shaobo

2016-10-01

We present a high-accuracy, low false-alarm rate, and low computational-cost methodology for removing stars and noise and detecting space debris with low signal-to-noise ratio (SNR) in optical image sequences. First, time-index filtering and bright star intensity enhancement are implemented to remove stars and noise effectively. Then, a multistage quasi-hypothesis-testing method is proposed to detect the pieces of space debris with continuous and discontinuous trajectories. For this purpose, a time-index image is defined and generated. Experimental results show that the proposed method can detect space debris effectively without any false alarms. When the SNR is higher than or equal to 1.5, the detection probability can reach 100%, and when the SNR is as low as 1.3, 1.2, and 1, it can still achieve 99%, 97%, and 85% detection probabilities, respectively. Additionally, two large sets of image sequences are tested to show that the proposed method performs stably and effectively.

An experimental and quantum chemical study of removal of utmostly quantified heavy metals in wastewater using coconut husk: A novel approach to mechanism.

PubMed

Malik, Reena; Dahiya, Shefali; Lata, Suman

2017-05-01

The present study explores the uptake capacity of low cost agricultural waste i.e.Unmodified Coconut (Cocos nucifera L.) Husk for the removal of heavy metal (Pb 2+ , Cu 2+ , Ni 2+ and Zn 2+ ) ions from industrial wastewater. The effect of various operational parameters such as adsorbent dose, high initial metal concentration (100mg/L-500mg/L), pH, temperature and agitation time on the removal of these ions has been investigated using batch experiments. The results showed that maximum uptake through adsorption occurred at 443.0mg/g (88.6%) for Cu, for Ni with 404.5mg/g (80.9%), 362.2mg/g (72.4%) for Pb 2+ and 338.0mg/g (67.6%) for Zn 2+ ion simultaneously. The adsorption capacity was found to be sensitive to the amount of adsorbent, heavy metal ion concentration, pH, temperature and contact time. The experimental statistics have been correlated and interpreted by a new proposed mechanism based upon quantum chemical study of the adsorbent. The theoretical study using quantum has provided the rich electron donation sites of Coconut Husk and hence proposed mechanism of removal. The various adsorption isotherms (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Flory-Huggins), SEM study and physico-chemical properties of the ions suit well to the observed data. Copyright © 2017 Elsevier B.V. All rights reserved.

[Effects of a physical restraint removal program on older people with dementia in residential care].

PubMed

Tortosa, M Ángeles; Granell, Rafael; Fuenmayor, Amadeo; Martínez, Mary

2016-01-01

To analyse the results of removing physical restraints from elderly patients with dementia living in nursing homes. This objective is part of a wider process of change in residential care. Quasi-experimental study conducted in two residences from May 2010 to May 2012. Information was collected at 7 time points and longitudinal analyses were performed. After training staff, the physical restraints in El Puig centre were phased out, while in the Conarda centre, restraints were still applied to elderly people. The main variables studied were: falls, psychotropic medication prescriptions, different indicators of mental impairment, and degree of dependence (Norton, NPI, Mini-mental, Tinetti, Barthel). In the El Puig centre all the physical restraints were removed. A slight improvement was seen in the number of falls, and their consequences. The ANOVA showed significant improvements in the centre that removed restraints in prescribing psychotropic medications, cognitive impairment, and behavioural changes. It is shown that removing physical restraints do not cause negative effects as regards the number of falls, and also positively affects the welfare and independence of elderly people (through changes in behaviour and mental impairment). Furthermore, it is demonstrated that this program must be accompanied by the reduction and control of medicines (withdrawal of the number of psychotropic prescriptions). Copyright © 2014 SEGG. Published by Elsevier Espana. All rights reserved.

Factors affecting degradation of dimethyl sulfoxide (DMSO) by fluidized-bed Fenton process.

PubMed

Bellotindos, Luzvisminda M; Lu, Meng-Hsuan; Methatham, Thanakorn; Lu, Ming-Chun

2014-12-01

In this study, the target compound is dimethyl sulfoxide (DMSO), which is used as a photoresist stripping solvent in the semiconductor and thin-film transistor liquid crystal display (TFT-LCD) manufacturing processes. The effects of the operating parameters (pH, Fe(2+) and H2O2 concentrations) on the degradation of DMSO in the fluidized-bed Fenton process were examined. This study used the Box-Behnken design (BBD) to investigate the optimum conditions of DMSO degradation. The highest DMSO removal was 98 % for pH 3, when the H2O2 to Fe(2+) molar ratio was 12. At pH 2 and 4, the highest DMSO removal was 82 %, when the H2O2 to Fe(2+) molar ratio was 6.5. The correlation of DMSO removal showed that the effect of the parameters on DMSO removal followed the order Fe(2+) > H2O2 > pH. From the BBD prediction, the optimum conditions were pH 3, 5 mM of Fe(2+), and 60 mM of H2O2. The difference between the experimental value (98 %) and the predicted value (96 %) was not significant. The removal efficiencies of DMSO, chemical oxygen demand (COD), total organic carbon (TOC), and iron in the fluidized-bed Fenton process were higher than those in the traditional Fenton process.

An experimental evaluation of potential scavenger effects on snake road mortality detections

USGS Publications Warehouse

Hubbard, Kaylan A.; Chalfoun, Anna D.

2012-01-01

As road networks expand and collisions between vehicles and wildlife become more common, accurately quantifying mortality rates for the taxa that are most impacted will be critical. Snakes are especially vulnerable to collisions with vehicles because of their physiology and behavior. Reptile road mortality is typically quantified using driving or walking surveys; however, scavengers can rapidly remove carcasses from the road and cause underestimation of mortality. Our objective was to determine the effect that scavengers might have had on our ability to accurately detect reptile road mortality during over 150 h and 4,000 km of driving surveys through arid shrublands in southwest Wyoming, which resulted in only two observations of mortality. We developed unique simulated snake carcasses out of Burbot (Lota lota), a locally invasive fish species, and examined removal rates across three different road types at three study sites. Carcass size was not a significant predictor of time of removal, and carcass removal was comparable during the daytime and nighttime hours. However, removal of simulated carcasses was higher on paved roads than unpaved or two-track roads at all study sites, with an average of 75% of the carcasses missing within 60 h compared to 34% and 31%, respectively. Scavengers may therefore negatively impact the ability of researchers to accurately detect herpetofaunal road mortality, especially for paved roads where road mortality is likely the most prevalent.

Characteristics of permanganate oxidation of TCE at low reagent concentrations.

PubMed

Woo, N C; Hyun, S G; Park, W W; Lee, E S; Schwartz, F W

2009-12-01

A controlled-release technique using potassium permanganate (KMnO4) has been recently developed as a long-term and semi-passive remediation scheme for dilute groundwater plumes of chlorinated solvents such as trichloroethylene (TCE) and perchloroethylene. Batch experiments were performed to evaluate TCE removal efficiencies of a low concentration of permanganate (MnO4-) solution and to estimate the optimum dose of permanganate required to remove low levels of TCE from groundwater plumes without leaving intermediate organic forms. Experimental results indicated that when the molar ratio of [MnO4-]0/[TCE]0 was about 10, 95% of the TCE in the plume was removed within less than 90 min, and about 90% of the chloride in the organic forms was converted into inorganic ions, while the TCE removal rates and the chloride conversion rates were considerably lower when the [TCE]0/ [MnO4-]0 values were lower. These data suggested that the [MnO4-]0 and the [MnO4-]0/[TCE]0 values would have strong effects on the efficiency and completeness of TCE oxidation. Further detailed investigations of the effect of [MnO4-]0 and [MnO4-]0/[TCE]0 values on the removal efficiencies and completeness of the TCE oxidation are warranted for successful application of the controlled-release KMnO4 technique in practice.

Chemical or electrochemical techniques, followed by ion exchange, for recycle of textile dye wastewater.

PubMed

Raghu, S; Ahmed Basha, C

2007-10-22

This paper examines the use of chemical or electrocoagulation treatment process followed by ion-exchange process of the textile dye effluent. The dye effluent was treated using polymeric coagulant (cationic dye-fixing agent) or electrocoagulation (iron and aluminum electrode) process under various conditions such as various current densities and effect of pH. Efficiencies of COD reduction, colour removal and power consumption were studied for each process. The chemical or electrochemical treatment are indented primarily to remove colour and COD of wastewater while ion exchange is used to further improve the removal efficiency of the colour, COD, Fe concentration, conductivity, alkalinity and total dissolved solids (TDS). From the results chemical coagulation, maximum COD reduction of about 81.3% was obtained at 300 mg/l of coagulant whereas in electrocoagulation process, maximum COD removal of about 92.31% (0.25 A/dm2) was achieved with energy consumption of about 19.29 k Wh/kg of COD and 80% (1A/dm(2)) COD removal was obtained with energy consumption of about 130.095 k Wh/kg of COD at iron and aluminum electrodes, respectively. All the experimental results, throughout the present study, have indicated that chemical or electrocoagulation treatment followed by ion-exchange methods were very effective and were capable of elevating quality of the treated wastewater effluent to the reuse standard of the textile industry.

Enhanced removal of Zn(2+) or Cd(2+) by the flocculating Chlorella vulgaris JSC-7.

PubMed

Alam, Md Asraful; Wan, Chun; Zhao, Xin-Qing; Chen, Li-Jie; Chang, Jo-Shu; Bai, Feng-Wu

2015-05-30

Microalgae are attracting attention due to their potentials in mitigating CO2 emissions and removing environmental pollutants. However, harvesting microalgal biomass from diluted cultures is one of the bottlenecks for developing economically viable processes for this purpose. Microalgal cells can be harvested by cost-effective sedimentation when flocculating strains are used. In this study, the removal of Zn(2+) and Cd(2+) by the flocculating Chlorella vulgaris JSC-7 was studied. The experimental results indicated that more than 80% Zn(2+) and 60% Cd(2+) were removed by the microalgal culture within 3 days in the presence up to 20.0mg/L Zn(2+) and 4.0mg/L Cd(2+), respectively, which were much higher than that observed with the culture of the non-flocculating C. vulgaris CNW11. Furthermore, the mechanism underlying this phenomenon was explored by investigating the effect of Zn(2+) and Cd(2+) on the growth and metabolic activities of the microalgal strains. It was found that the flocculation of the microalga improved its growth, synthesis of photosynthetic pigments and antioxidation activity under the stressful conditions, indicating a better tolerance to the heavy metal ions for a potential in removing them more efficiently from contaminated wastewaters, together with a bioremediation of other nutritional components contributed to the eutrophication of aquatic ecosystems. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption of bentazon on CAT and CARBOPAL activated carbon: Experimental and computational study

NASA Astrophysics Data System (ADS)

Spaltro, Agustín; Simonetti, Sandra; Torrellas, Silvia Alvarez; Rodriguez, Juan Garcia; Ruiz, Danila; Juan, Alfredo; Allegretti, Patricia

2018-03-01

Removal of the bentazon by adsorption on two different types of activated carbon was investigated under various experimental conditions.Kinetics of adsorption is followed and the adsorption isotherms of the pesticide are determined. The effects of the changes in pH, ionic strength and temperature are analyzed. Computational simulation was employed to analyze the geometry and the energy of pesticide absorption on activated carbon. Concentration of bentazon decreases while increase all the variables, from the same initial concentration. Experimental data for equilibrium was analyzed by three models: Langmuir, Freundlich and Guggenheim-Anderson-de Boer isotherms. Pseudo-first and pseudo-second-order kinetics are tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of bentazon by CAT and CARBOPAL with coefficients of correlation R2 = 0.9996 and R2 = 0.9993, respectively. The results indicated that both CAT and CARBOPAL are very effective for the adsorption of bentazon from aqueous solutions, but CAT carbon has the greater capacity.

Cutting a young-growth, mixed-conifer stand to California Forest Practice Act Standards

Treesearch

Philip M. McDonald

1973-01-01

Cutting by the minimum standard of the Rules of California's North Sierra Pine Forest District was evaluated for effects on species composition, seed fall, regeneration, and residual growth at the Challenge Experimental Forest, central California. Cutting removed 74 percent of the stand basal area and 94 percent of the merchantable volume. The heavy cut changed...

Response of individual Douglas-fir trees to release.

Treesearch

Donald L. Reukema

1961-01-01

To evaluate effects of different degrees of release on individual Douglas-fir trees, a study was started in 1952 in a 41-year-old, site IV stand at the Wind River Experimental Forest. A remeasurement at the end of four growing seasons showed that dominants respond more quickly and positively to the removal of competing trees than codominants or intermediates. A second...

Comparison of Fixed Diameter-Limit and Selection Cutting in Northern Conifers

Treesearch

Laura S. Kenefic; Paul E. Sendak; John C. Brissette

2005-01-01

Diameter-limit cutting is a common type of harvest in which all merchantable trees above specific size thresholds are removed. Despite a long history of application, controlled experiments of these harvests are rare and the cumulative effects of repeated diameter-limit cuts are largely unknown. The Penobscot Experimental Forest in Maine is the location of a long-term...

Development of design information for molecular-sieve type regenerative CO2-removal systems

NASA Technical Reports Server (NTRS)

Wright, R. M.; Ruder, J. M.; Dunn, V. B.; Hwang, K. C.

1973-01-01

Experimental and analytic studies were conducted with molecular sieve sorbents to provide basic design information, and to develop a system design technique for regenerable CO2-removal systems for manned spacecraft. Single sorbate equilibrium data were obtained over a wide range of conditions for CO2, water, nitrogen, and oxygen on several molecular sieve and silica gel sorbents. The coadsorption of CO2 with water preloads, and with oxygen and nitrogen was experimentally evaluated. Mass-transfer, and some limited heat-transfer performance evaluations were accomplished under representative operating conditions, including the coadsorption of CO2 and water. CO2-removal system performance prediction capability was derived.

Spot breeding method to evaluate the determinism of magnetorheological finishing

NASA Astrophysics Data System (ADS)

Yang, Hang; He, Jianguo; Huang, Wen; Zhang, Yunfei

2017-03-01

The influences of immersion depth of magnetorheological finishing (MRF) on the shape and material removal rate (MRR) of removal function are theoretically investigated to establish the spot transition mechanism. Based on this mechanism, for the first time, the spot breeding method to predict the shape and removal rate of MRF spot is proposed. The UBK7 optical parts are polished to verify the proposed method on experimental installation PKC-1000Q2 developed by ourselves. The experimental results reveal that the predictions of shape and MRR with this method are precise. The proposed method provides a basis for analyzing the determinism of MRF due to geometry of the process.

Application of Vacuum Swing Adsorption for Carbon Dioxide and Water Vapor Removal from Manned Spacecraft Atmospheres

NASA Technical Reports Server (NTRS)

Knox, J.; Fulda, P.; Howard, D.; Ritter, J.; Levan, M.

2007-01-01

The design and testing of a vacuum-swing adsorption process to remove metabolic 'water and carbon dioxide gases from NASA's Orion crew exploration vehicle atmosphere is presented. For the Orion spacecraft, the sorbent-based atmosphere revitalization (SBAR) system must remove all metabolic water, a technology approach 1Lhathas not been used in previous spacecraft life support systems. Design and testing of a prototype SBAR in sub-scale and full-scale configurations is discussed. Experimental and analytical investigations of dual-ended and single-ended vacuum desorption are presented. An experimental investigation of thermal linking between adsorbing and desorbing columns is also presented.

[Treatment of organic waste gas by adsorption rotor].

PubMed

Zhu, Run-Ye; Zheng, Liang-Wei; Mao, Yu-Bo; Wang, Jia-De

2013-12-01

The adsorption rotor is applicable to treating organic waste gases with low concentration and high air volume. The performance of adsorption rotor for purifying organic waste gases was investigated in this paper. Toluene was selected as the simulative gaseous pollutant and the adsorption rotor was packed with honeycomb modified 13X molecular sieves (M-13X). Experimental results of the fixed adsorption and the rotor adsorption were analyzed and compared. The results indicated that some information on the fixed adsorption was useful for the rotor adsorption. Integrating the characteristics of the adsorbents, waste gases and the structures of the rotor adsorption, the formulas on optimal rotor speed and cycle removal efficiency of the adsorption rotor were deduced, based on the mass and heat balances of the adsorbing process. The numerical results were in good agreement with the experimental data, which meant that the formulas on optimal rotor speed and cycle removal efficiency could be effectively applied in design and operation of the adsorption rotor.

Biosorption kinetics of heavy metals by leaf biomass of Jatropha curcas in single and multi-metal system.

PubMed

Rawat, Anand Prabha; Giri, Krishna; Rai, J P N

2014-03-01

Biosorption of Cu(2+), Zn(2+), and Cr(6+) from aqueous solutions by leaf biomass of Jatropha curcas was investigated as a function of biomass concentration, initial metal ion concentration, contact time, and pH of the solution systematically. The aim of this study was to optimize biosorption process and find out a suitable kinetic model for the metal removal in single and multi-metal system. The experimental data were analyzed using two sorption kinetic models, viz., pseudo-first- and pseudo-second-order equations, to determine the best fit equation for the biosorption of metal ions Cu(2+), Zn(2+), and Cr(6+) onto the leaf biomass of J. curcas in different metal systems. The experimental data fitted well the pseudo-second-order equation and provided the best correlation for the biosorption process. The findings of the present investigation revealed that J. curcas leaf biomass was an eco-friendly and cost-effective biosorbent for the removal of heavy metal ions from wastewater.

Gas treatment in trickle-bed biofilters: biomass, how much is enough?

PubMed

Alonso, C; Suidan, M T; Sorial, G A; Smith, F L; Biswas, P; Smith, P J; Brenner, R C

1997-06-20

The objective of this article is to define and validate a mathematical model that desribes the physical and biological processes occurring in a trickle-bed air biofilter for waste gas treatment. This model considers a two-phase system, quasi-steady-state processes, uniform bacterial population, and one limiting substrate. The variation of the specific surface area with bacterial growth is included in the model, and its effect on the biofilter performance is analyzed. This analysis leads to the conclusion that excessive accumulation of biomass in the reactor has a negative effect on contaminant removal efficiency. To solve this problem, excess biomass is removed via full media fluidization and backwashing of the biofilter. The backwashing technique is also incorporated in the model as a process variable. Experimental data from the biodegradation of toluene in a pilot system with four packed-bed reactors are used to validate the model. Once the model is calibrated with the estimation of the unknown parameters of the system, it is used to simulate the biofilter performance for different operating conditions. Model predictions are found to be in agreement with experimental data. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 583-594, 1997.

An examination of the effects of mountaintop removal coal mining on respiratory symptoms and COPD using propensity scores.

PubMed

Hendryx, Michael; Luo, Juhua

2015-01-01

Previous research on public health consequences of mountaintop removal (MTR) coal mining has been limited by the observational nature of the data. The current study used propensity scores, a method designed to overcome this limitation, to draw more confident causal inferences about mining effects on respiratory health using non-experimental data. These data come from a health survey of 682 adults residing in two rural areas of Virginia, USA characterized by the presence or absence of MTR mining. Persons with a history of occupational exposure as coal miners were excluded. Nine covariates including age, sex, current and former smoking, overweight, obesity, high school education, college education, and exposure to coal as a home-heating source were selected to estimate propensity scores. Propensity scores were tested for balance and then used as weights to create quasi-experimental exposed and unexposed groups. Results indicated that persons in the mountaintop mining group had significantly (p < 0.0001) elevated prevalence of respiratory symptoms and chronic obstructive pulmonary disease. The results suggest that impaired respiratory health results from exposure to MTR environments and not from other risks.

Improving the ablation efficiency of excimer laser systems with higher repetition rates through enhanced debris removal and optimized spot pattern.

PubMed

Arba-Mosquera, Samuel; Klinner, Thomas

2014-03-01

To evaluate the reasons for the required increased radiant exposure for higher-repetition-rate excimer lasers and determine experimentally possible compensations to achieve equivalent ablation profiles maintaining the same single-pulse energies and radiant exposures for laser repetition rates ranging from 430 to 1000 Hz. Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany. Experimental study. Poly(methyl methacrylate) (PMMA) plates were photoablated. The pulse laser energy was maintained during all experiments; the effects of the flow of the debris removal, the shot pattern for the correction, and precooling the PMMA plates were evaluated in terms of achieved ablation versus repetition rate. The mean ablation performance ranged from 88% to 100%; the variability between the profile measurements ranged from 1.4% to 6.2%. Increasing the laser repetition rate from 430 Hz to 1000 Hz reduced the mean ablation performance from 98% to 91% and worsened the variability from 1.9% to 4.3%. Increasing the flow of the debris removal, precooling the PMMA plates to -18°C, and adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the variability. Only adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the mean ablation performance. The ablation performance of higher-repetition-rate excimer lasers on PMMA improved with improvements in the debris removal systems and shot pattern. More powerful debris removal systems and smart shot patterns in terms of thermal response improved the performance of these excimer lasers. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The Effects of Military Change of Station Moves on Spousal Earnings

DTIC Science & Technology

2016-10-01

within the literature on tied migration, military wives are an ideal “ quasi - experimental group , because such women represent perhaps the ideal typical...moves (one or two years prior to the current year) as part of the control group . Table 5.3 reports results from an extended model that also controls ...for effects of moves one or two years earlier, removing those spouse-year observations from the control group . Among spouses who ever appear in our

Correction for the T1 Effect Incorporating Flip Angle Estimated by Kalman Filter in Cardiac-Gated Functional MRI

PubMed Central

Shin, Jaemin; Ahn, Sinyeob; Hu, Xiaoping

2015-01-01

Purpose To develop an improved and generalized technique for correcting T1-related signal fluctuations (T1 effect) in cardiac-gated functional magnetie resonance imaging (fMRI) data with flip angle estimation. Theory and Methods Spatial maps of flip angle and T1 are jointly estimated from cardiac-gated time series using a Kalman filter. These maps are subsequently used for removing the T1 effect in the presence of B1 inhomogeneity. The new technique was compared with a prior technique that uses T1 only while assuming a homogeneous flip angle of 90°. The robustness of the new technique is demonstrated with simulated and experimental data. Results Simulation results revealed that the new method led to increased temporal signal-to-noise ratio across a large range of flip angles, T1s, and stimulus onset asynchrony means compared to the T1 only approach. With the experimental data, the new approach resulted in higher average gray matter temporal signal-to-noise ratio of seven subjects (84 vs. 48). The new approach also led to a higher statistical score of activation in the lateral geniculate nucleus (P < 0.002). Conclusion The new technique is able to remove the T1 effect robustly and is a promising tool for improving the ability to map activation in fMRI, especially in subcortical regions. PMID:23390029

Experimentation on the anaerobic filter reactor for biogas production using rural domestic wastewater

NASA Astrophysics Data System (ADS)

Leju Celestino Ladu, John; Lü, Xi-wu; Zhong, Zhaoping

2017-08-01

The biogas production from anaerobic filter (AF) reactor was experimented in Taihu Lake Environmental Engineering Research Center of Southeast University, Wuxi, China. Two rounds of experimental operations were conducted in a laboratory scale at different Hydraulic retention time (HRT) and wastewater temperature. The biogas production rate during the experimentation was in the range of 4.63 to 11.78 L/d. In the first experimentation, the average gas production rate was 10.08 L/d, and in the second experimentation, the average gas production rate was 4.97 L/d. The experimentation observed the favorable Hydraulic Retention Time and wastewater temperature in AF was three days and 30.95°C which produced the gas concentration of 11.78 L/d. The HRT and wastewater temperature affected the efficiency of the AF process on the organic matter removal and nutrients removal as well. It can be deduced from the obtained results that HRT and wastewater temperature directly affects the efficiency of the AF reactor in biogas production. In conclusion, anaerobic filter treatment of organic matter substrates from the rural domestic wastewater increases the efficiency of the AF reactor on biogas production and gives a number of benefits for the management of organic wastes as well as reduction in water pollution. Hence, the operation of the AF reactor in rural domestic wastewater treatment can play an important element for corporate economy of the biogas plant, socio-economic aspects and in the development of effective and feasible concepts for wastewater management, especially for people in rural low-income areas.

Hybrid ICA-Regression: Automatic Identification and Removal of Ocular Artifacts from Electroencephalographic Signals.

PubMed

Mannan, Malik M Naeem; Jeong, Myung Y; Kamran, Muhammad A

2016-01-01

Electroencephalography (EEG) is a portable brain-imaging technique with the advantage of high-temporal resolution that can be used to record electrical activity of the brain. However, it is difficult to analyze EEG signals due to the contamination of ocular artifacts, and which potentially results in misleading conclusions. Also, it is a proven fact that the contamination of ocular artifacts cause to reduce the classification accuracy of a brain-computer interface (BCI). It is therefore very important to remove/reduce these artifacts before the analysis of EEG signals for applications like BCI. In this paper, a hybrid framework that combines independent component analysis (ICA), regression and high-order statistics has been proposed to identify and eliminate artifactual activities from EEG data. We used simulated, experimental and standard EEG signals to evaluate and analyze the effectiveness of the proposed method. Results demonstrate that the proposed method can effectively remove ocular artifacts as well as it can preserve the neuronal signals present in EEG data. A comparison with four methods from literature namely ICA, regression analysis, wavelet-ICA (wICA), and regression-ICA (REGICA) confirms the significantly enhanced performance and effectiveness of the proposed method for removal of ocular activities from EEG, in terms of lower mean square error and mean absolute error values and higher mutual information between reconstructed and original EEG.

Hybrid ICA—Regression: Automatic Identification and Removal of Ocular Artifacts from Electroencephalographic Signals

PubMed Central

Mannan, Malik M. Naeem; Jeong, Myung Y.; Kamran, Muhammad A.

2016-01-01

Electroencephalography (EEG) is a portable brain-imaging technique with the advantage of high-temporal resolution that can be used to record electrical activity of the brain. However, it is difficult to analyze EEG signals due to the contamination of ocular artifacts, and which potentially results in misleading conclusions. Also, it is a proven fact that the contamination of ocular artifacts cause to reduce the classification accuracy of a brain-computer interface (BCI). It is therefore very important to remove/reduce these artifacts before the analysis of EEG signals for applications like BCI. In this paper, a hybrid framework that combines independent component analysis (ICA), regression and high-order statistics has been proposed to identify and eliminate artifactual activities from EEG data. We used simulated, experimental and standard EEG signals to evaluate and analyze the effectiveness of the proposed method. Results demonstrate that the proposed method can effectively remove ocular artifacts as well as it can preserve the neuronal signals present in EEG data. A comparison with four methods from literature namely ICA, regression analysis, wavelet-ICA (wICA), and regression-ICA (REGICA) confirms the significantly enhanced performance and effectiveness of the proposed method for removal of ocular activities from EEG, in terms of lower mean square error and mean absolute error values and higher mutual information between reconstructed and original EEG. PMID:27199714

Characterization of coal gasification slag-based activated carbon and its potential application in lead removal.

PubMed

Xu, Yiting; Chai, Xiaoli

2018-02-01

Highly porous activated carbons were prepared from a coal gasification slag (CGS) precursor, by KOH activation to remove Pb 2+ from aqueous solution. The effects of pretreatment methods and activation parameters on the properties of the activated carbon were investigated, such as KOH/CGS mass ratio, activation temperature and activation time. The results showed that the maximum Brunauer-Emmett-Teller surface area and total pore volume with the value of 2481 m 2  g -1 and of 1.711 cc g -1 were obtained at a KOH/CGS ratio of 3.0 by physical mixing, an activation temperature of 750°C and an activation time of 80 min. SEM, FTIR and EA analyses indicated that pronounced pores existed on the exterior surface of the activated samples, and the contents of H and O decreased due to the loss of surface chemical groups during activation. Experimental data for the Pb 2+ adsorption were fitted well by Freundlich equation and a pseudo-second-order model with a maximum experimental adsorption capacity of 141 mg/g. All of the results indicated that CGS could be a promising material to prepare porous activated carbon for Pb 2+ removal from wastewater.

Optimization of the photoelectrocatalytic oxidation of landfill leachate using copper and nitrate co-doped TiO2 (Ti) by response surface methodology

PubMed Central

Zhou, Shaoqi; Feng, Xinbin

2017-01-01

In this paper, a statistically-based experimental design with response surface methodology (RSM) was employed to examine the effects of functional conditions on the photoelectrocatalytic oxidation of landfill leachate using a Cu/N co-doped TiO2 (Ti) electrode. The experimental design method was applied to response surface modeling and the optimization of the operational parameters of the photoelectro-catalytic degradation of landfill leachate using TiO2 as a photo-anode. The variables considered were the initial chemical oxygen demand (COD) concentration, pH and the potential bias. Two dependent parameters were either directly measured or calculated as responses: chemical oxygen demand (COD) removal and total organic carbon (TOC) removal. The results of this investigation reveal that the optimum conditions are an initial pH of 10.0, 4377.98mgL-1 initial COD concentration and 25.0 V of potential bias. The model predictions and the test data were in satisfactory agreement. COD and TOC removals of 67% and 82.5%, respectively, were demonstrated. Under the optimal conditions, GC/MS showed 73 organic micro-pollutants in the raw landfill leachate which included hydrocarbons, aromatic compounds and esters. After the landfill leachate treatment processes, 38 organic micro-pollutants disappeared completely in the photoelectrocatalytic process. PMID:28671943

Surface adsorption of poisonous Pb(II) ions from water using chitosan functionalised magnetic nanoparticles.

PubMed

Christopher, Femina Carolin; Anbalagan, Saravanan; Kumar, Ponnusamy Senthil; Pannerselvam, Sundar Rajan; Vaidyanathan, Vinoth Kumar

2017-06-01

In this study, chitosan functionalised magnetic nano-particles (CMNP) was synthesised and utilised as an effective adsorbent for the removal of Pb(II) ions from aqueous solution. The experimental studies reveal that adsorbent material has finer adsorption capacity for the removal of heavy metal ions. Parameters affecting the adsorption of Pb(II) ions on CMNP, such as initial Pb(II) ion concentration, contact time, solution pH, adsorbent dosage and temperature were studied. The adsorption equilibrium study showed that present adsorption system followed a Freundlich isotherm model. The experimental kinetic studies on the adsorption of Pb(II) ions exhibited that present adsorption process best obeyed with pseudo-first order kinetics. The maximum monolayer adsorption capacity of CMNP for the removal of Pb(II) ions was found to be 498.6 mg g -1 . The characterisation of present adsorbent material was done by FTIR, energy disperse X-ray analysis and vibrating sample magnetometer studies. Thermodynamic parameters such as Gibbs free energy (Δ G °), enthalpy (Δ H °) and entropy (Δ S °) have declared that the adsorption process was feasible, exothermic and spontaneous in nature. Sticking probability reported that adsorption of Pb(II) ions on CMNP was favourable at lower temperature and sticking capacity of Pb(II) ions was very high.

Adsorption potential of a modified activated carbon for the removal of nitrogen containing compounds from model fuel

NASA Astrophysics Data System (ADS)

Anisuzzaman, S. M.; Krishnaiah, D.; Alfred, D.

2018-02-01

The purpose of this study is to find the effect of the modified activated carbon (MAC) on the adsorption activity for nitrogen containing compounds (NCC) removal from model fuel. Modification of commercial activated carbon (AC) involved impregnation with different ratios of sulfuric acid solution. Pseudo-first and pseudo-second order kinetic models were applied to study the adsorption kinetics, while the adsorption isotherms were used for the evaluation of equilibrium data. All of the experimental data were analyzed using ultraviolet-visible spectroscopy after adsorption experiment between different concentration dosage of adsorbent and model fuel. It has been found that adsorption of NCC by MAC was best fit is the Langmuir isotherm for quinoline (QUI) and Freundlich isotherm for indole (IND) with a maximum adsorption capacity of 0.13 mg/g and 0.16 mg/g respectively. Based on the experimental data, pseudo-first order exhibited the best fit for QUI with linear regression (R2) ranges from 0.0.9777 to 0.9935 and pseudo-second order exhibited the best fit for IND with linear regression (R2) ranges from 0.9701 to 0.9962. From the adsorption isotherm and kinetic studies result proven that commercial AC shows great potential in removing nitrogen.

Pulsed discharge plasma induced Fenton-like reactions for the enhancement of the degradation of 4-chlorophenol in water.

PubMed

Hao, Xiaolong; Zhou, Minghua; Xin, Qing; Lei, Lecheng

2007-02-01

To sufficiently utilize chemically active species and enhance the degradation rate and removal efficiency of toxic and biorefractory organic pollutant para-chlorophenol (para-CP), the introductions of iron metal ions (Fe2+/Fe3+) into either pulsed discharge plasma (PDP) process or the PDP process with TiO2 photo-catalyst were tentatively performed. The experimental results showed that under the same experimental condition, the degradation rate and removal efficiency of para-CP were greatly enhanced by the introduction of iron ions (Fe2+/Fe3+) into the PDP process. Moreover, when iron ions and TiO2 were added together in the PDP process, the degradation rate and removal energy of para-CP further improved. The possible mechanism was discussed that the obvious promoting effects were attributed to ferrous ions via plasma induced Fenton-like reactions by UV light irradiation excited and hydrogen peroxide formed in pulsed electrical discharge, resulting in a larger amount of hydroxyl radicals produced from the residual hydrogen peroxide. In addition, the regeneration of ferric ions to ferrous ions facilitates the progress of plasma induced Fenton-like reactions by photo-catalytic reduction of UV light, photo-catalytic reduction on TiO2 surface and electron transfer of quinone intermediates, i.e. 1,4-hydroquinone and 1,4-benzoquinone.

Artificial intelligence based model for optimization of COD removal efficiency of an up-flow anaerobic sludge blanket reactor in the saline wastewater treatment.

PubMed

Picos-Benítez, Alain R; López-Hincapié, Juan D; Chávez-Ramírez, Abraham U; Rodríguez-García, Adrián

2017-03-01

The complex non-linear behavior presented in the biological treatment of wastewater requires an accurate model to predict the system performance. This study evaluates the effectiveness of an artificial intelligence (AI) model, based on the combination of artificial neural networks (ANNs) and genetic algorithms (GAs), to find the optimum performance of an up-flow anaerobic sludge blanket reactor (UASB) for saline wastewater treatment. Chemical oxygen demand (COD) removal was predicted using conductivity, organic loading rate (OLR) and temperature as input variables. The ANN model was built from experimental data and performance was assessed through the maximum mean absolute percentage error (= 9.226%) computed from the measured and model predicted values of the COD. Accordingly, the ANN model was used as a fitness function in a GA to find the best operational condition. In the worst case scenario (low energy requirements, high OLR usage and high salinity) this model guaranteed COD removal efficiency values above 70%. This result is consistent and was validated experimentally, confirming that this ANN-GA model can be used as a tool to achieve the best performance of a UASB reactor with the minimum requirement of energy for saline wastewater treatment.

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.

The effects of different irrigation protocols on removing calcium hydroxide from the root canals.

PubMed

Üstün, Y; Aslan, T; Sagsen, B; Dincer, A N

2016-01-01

The aim of this study was to evaluate the efficiencies of different irrigation protocols and solutions in the removal of calcium hydroxide (Ca[OH]2). Sixty-eight maxillary incisors were used. Root canals were prepared and filled with Ca(OH)2. Two control (n = 4) and six experimental groups (n = 10) were adjusted: Group 1:1% peracetic acid (PAA) + master apical file (MAF); Group 2: 17% ethylenediaminetetraacetic acid (EDTA) + MAF; Group 3: 9% 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) + MAF; Group 4: 1% PAA + ultrasonic activation (UA); Group 5: 17% EDTA + UA; Group 6: 9% HEBP + UA. The cleanliness of root canal thirds were evaluated with scanning electron microscopy. Statistical analysis were performed (α = 0.05). At coronal thirds; PAA + UA was superior to EDTA + MAF, HEBP + MAF; and PAA + MAF was superior to EDTA + MAF, HEBP + MAF (P < 0.05). At middle thirds; PAA + MAF and PAA + UA were superior to EDTA + MAF and EDTA + UA; and, PAA + UA was superior to HEBP + MAF (P < 0.05). There were no significant differences among the rest of the experimental groups (P > 0.05). Complete removal of Ca(OH)2could not be achieved by none of the irrigants at all root thirds.

Managing native predators: Evidence from a partial removal of raccoons (Procyon lotor) on the Outer Banks of North Carolina, USA

USGS Publications Warehouse

Stocking, Jessica J.; Simons, Theodore R.; Parsons, Arielle W.; O'Connell, Allan F.

2017-01-01

Raccoons (Procyon lotor) are important predators of ground-nesting species in coastal systems. They have been identified as a primary cause of nest failure for the American Oystercatcher (Haematopus palliatus) throughout its range. Concerns over the long-term effects of raccoon predation and increased nest success following a hurricane inspired a mark-resight study of the raccoon population on a barrier island off North Carolina, USA. Approximately half of the raccoons were experimentally removed in 2008. Nests (n = 700) were monitored on two adjacent barrier islands during 2004–2013. Daily nest survival estimates were highest for 2004 (0.974 ± 0.005) and lowest for 2007 and 2008 (0.925 ± 0.009 and 0.925 ± 0.010, respectively). The only model in our candidate set that received any support included island and time of season, along with a diminishing effect of the hurricane and a constant, 5-year effect of the raccoon removal. For both hurricane and raccoon removal, however, the support for island-specific effects was weak (β = -0.204 ± 0.116 and 0.146 ± 0.349, respectively). We conclude that either the raccoon reduction was inadequate, or factors other than predation cause more variation in nest success than previously recognized. A multi-faceted approach to management aimed at reducing nest losses to storm overwash, predation, and human disturbance is likely to yield the largest population level benefits.

Enzymatic catalysis treatment method of meat industry wastewater using lacasse.

PubMed

Thirugnanasambandham, K; Sivakumar, V

2015-01-01

The process of meat industry produces in a large amount of wastewater that contains high levels of colour and chemical oxygen demand (COD). So they must be pretreated before their discharge into the ecological system. In this paper, enzymatic catalysis (EC) was adopted to treat the meat wastewater. Box-Behnken design (BBD), an experimental design for response surface methodology (RSM), was used to create a set of 29 experimental runs needed for optimizing of the operating conditions. Quadratic regression models with estimated coefficients were developed to describe the colour and COD removals. The experimental results show that EC could effectively reduce colour (95 %) and COD (86 %) at the optimum conditions of enzyme dose of 110 U/L, incubation time of 100 min, pH of 7 and temperature of 40 °C. RSM could be effectively adopted to optimize the operating multifactors in complex EC process.

Effective NOx remediation from a surrogate flue gas using the US NRL Electra electron beam facility

NASA Astrophysics Data System (ADS)

Petrova, Tz. B.; Petrov, G. M.; Wolford, M. F.; Giuliani, J. L.; Ladouceur, H. D.; Hegeler, F.; Myers, M. C.; Sethian, J. D.

2017-02-01

Nitric oxide (NOx) emission is under restrictive federal regulations because of its negative impact on atmosphere, biosphere, and human health. Therefore, its removal has been a subject of extensive research to develop new efficient and cost effective techniques that can be applied on an industrial scale. In this work, we study both experimentally and theoretically an effective removal of NOx pollutants from a surrogate flue gas (SFG) using high power electron beam (e-beam) pulses. SFG is a simulant for exhaust from coal combustion power plants (82% N2, 6% O2, 12% CO2, and ˜100 ppm of NOx). The pulsed electron beam is generated using the United States Naval Research Laboratory Electra facility, which delivers e-beams with energies of ˜500 keV and a power pulse duration of ˜140 ns. During the e-beam irradiation, the energetic electrons generate a non-equilibrium plasma containing chemically active species, which then react with NOx to form harmless substances. A non-equilibrium time-dependent model is developed to describe NOx remediation from SFG. The model combines e-beam deposition rates obtained by solving the electron Boltzmann equation and extensive plasma chemistry modeling, which follows the species on a time scale from sub-nanoseconds to a few seconds. NOx decomposition as a function of electron beam parameters is studied. It is demonstrated experimentally that short (ns) pulses are the most efficient for NOx removal. A sharp reduction of NOx was measured with e-beam power deposition increasing, following the trend predicted by the model, achieving a 20 fold reduction to ˜5 ppm at energy deposition ˜20 J/l.

Comparison of hydraulics and particle removal efficiencies in a mixed cell raceway and burrows pond rearing system

USDA-ARS?s Scientific Manuscript database

We compared the hydrodynamics of replicate experimental mixed cell and replicate standard Burrows pond rearing systems at the Dworshak National Fish Hatchery, ID, in an effort to identify methods for improved solids removal. We measured and compared the hydraulic residence time, particle removal eff...

Improving material removal determinacy based on the compensation of tool influence function

NASA Astrophysics Data System (ADS)

Zhong, Bo; Chen, Xian-hua; Deng, Wen-hui; Zhao, Shi-jie; Zheng, Nan

2018-03-01

In the process of computer-controlled optical surfacing (CCOS), the key of correcting the surface error of optical components is to ensure the consistency between the simulated tool influence function and the actual tool influence function (TIF). The existing removal model usually adopts the fixed-point TIF to remove the material with the planning path and velocity, and it considers that the polishing process is linear and time invariant. However, in the actual polishing process, the TIF is a function related to the feed speed. In this paper, the relationship between the actual TIF and the feed speed (i.e. the compensation relationship between static removal and dynamic removal) is determined by experimental method. Then, the existing removal model is modified based on the compensation relationship, to improve the conformity between simulated and actual processing. Finally, the surface error modification correction test are carried out. The results show that the fitting degree of the simulated surface and the experimental surface is better than 88%, and the surface correction accuracy can be better than 1/10 λ (Λ=632.8nm).

Ammonium stimulates nitrate reduction during simultaneous nitrification and denitrification process by Arthrobacter arilaitensis Y-10.

PubMed

He, Tengxia; Xie, Deti; Li, Zhenlun; Ni, Jiupai; Sun, Quan

2017-09-01

The ability of Arthrobacter arilaitensis Y-10 for nitrogen removal from simulated wastewater was studied. Results showed that ammonium was the best inorganic nitrogen for strain Y-10's cell growth, which could also promote nitrate reduction. Approximately 100.0% of ammonium was removed in the nitrogen removal experiments. The nitrate removal efficiency was 73.3% with nitrate as sole nitrogen source, and then the nitrate efficiency was increased to 85.3% and 100.0% with ammonium and nitrate (both about 5 or 100mg/L) as the mixed nitrogen sources. Nitrite accumulation was observed in presence of ammonium and nitrate. When the concentration of sole nitrite nitrogen was 10.31mg/L, the nitrite removal efficiency was 100.0%. Neither ammonium nor nitrate was accumulated during the whole experimental process. All experimental results indicated that A. arilaitensis Y-10 could remove ammonium, nitrate and nitrite at 15°C from wastewater, and could also perform simultaneous nitrification and denitrification under aerobic condition. Copyright © 2017. Published by Elsevier Ltd.

Synthesis of iron oxyhydroxide-coated rice straw (IOC-RS) and its application in arsenic(V) removal from water.

PubMed

Ouédraogo, Igor W K; Pehlivan, Erol; Tran, Hien T; Bonzi-Coulibaly, Yvonne L; Zachmann, Dieter; Bahadir, Müfit

2015-09-01

Because of the recognition that arsenic (As) at low concentrations in drinking water causes severe health effects, the technologies of As removal have become increasingly important. In this study, a simplified and effective method was used to immobilize iron oxyhydroxide onto a pretreated naturally occurring rice straw (RS). The modified RS adsorbent was characterized, using scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analyzer, and surface area analyzer. Experimental batch data of As(V) adsorption were modeled by the isotherms and kinetics models. Although all isotherms, the Langmuir model fitted the equilibrium data better than Freundlich and Dubinin-Radushkevich models and confirmed the surface homogeneity of adsorbent. The iron oxyhydroxide-coated rice straw (IOC-RS) was found to be effective for the removal of As(V) with 98.5% sorption efficiency at a concentration of <50 mg/L of As(V) solution, and thus maximum uptake capacity is ∼22 and 20 mg As(V)/g of IOC-RS at pH 4 and 6, respectively. The present study might provide new avenues to achieve the As concentrations required for drinking water recommended by the World Health Organization.

Removal of lindane from an aqueous solution by using aminopropyl silica gel-immobilized calix[6]arene.

PubMed

Tor, Ali; Aydin, Mehmet Emin; Aydin, Senar; Tabakci, Mustafa; Beduk, Fatma

2013-11-15

An aminopropyl silica gel-immobilized calix[6]arene (C[6]APS) has been used for the removal of lindane from an aqueous solution in batch sorption technique. The C[6]APS was synthesized with p-tert-butylcalix[6]arene hexacarboxylate derivative and aminopropyl silica gel in the presence of N,N'-diisopropyl carbodiimide coupling reagent. The sorption study was carried out as functions of solution pH, contact time, initial lindane concentration, C[6]APS dosage and ionic strength of solution. The matrix effect of natural water samples on the sorption efficiency of C[6]APS was also investigated. Maximum lindane removal was obtained at a wide pH range of 2-8 and sorption equilibrium was achieved in 2h. The isotherm analysis indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models. Increasing ionic strength of the solutions increased the sorption efficiency and matrix of natural water samples had no effect on the sorption of lindane. By using multilinear regression model, regression equation was also developed to explain the effects of the experimental variables. Copyright © 2013 Elsevier B.V. All rights reserved.

A review of vegetated buffers and a meta-analysis of their mitigation efficacy in reducing nonpoint source pollution.

PubMed

Zhang, Xuyang; Liu, Xingmei; Zhang, Minghua; Dahlgren, Randy A; Eitzel, Melissa

2010-01-01

Vegetated buffers are a well-studied and widely used agricultural management practice for reducing nonpoint-source pollution. A wealth of literature provides experimental data on their mitigation efficacy. This paper aggregated many of these results and performed a meta-analysis to quantify the relationships between pollutant removal efficacy and buffer width, buffer slope, soil type, and vegetation type. Theoretical models for removal efficacy (Y) vs. buffer width (w) were derived and tested against data from the surveyed literature using statistical analyses. A model of the form Y = K x (1-e(-bxw)), (0 < K < or = 100) successfully captured the relationship between buffer width and pollutant removal, where K reflects the maximum removal efficacy of the buffer and b reflects its probability to remove any single particle of pollutant in a unit distance. Buffer width alone explains 37, 60, 44, and 35% of the total variance in removal efficacy for sediment, pesticides, N, and P, respectively. Buffer slope was linearly associated with sediment removal efficacy either positively (when slope < or = 10%) or negatively (when slope > 10%). Buffers composed of trees have higher N and P removal efficacy than buffers composed of grasses or mixtures of grasses and trees. Soil drainage type did not show a significant effect on pollutant removal efficacy. Based on our analysis, a 30-m buffer under favorable slope conditions (approximately 10%) removes more than 85% of all the studied pollutants. These models predicting optimal buffer width/slope can be instrumental in the design, implementation, and modeling of vegetated buffers for treating agricultural runoff.

Ant-mediated seed dispersal in a warmed world

PubMed Central

Patterson, Courtney M.; Rodriguez-Cabal, Mariano A.; Ribbons, Relena R.; Dunn, Robert R.; Sanders, Nathan J.

2014-01-01

Climate change affects communities both directly and indirectly via changes in interspecific interactions. One such interaction that may be altered under climate change is the ant-plant seed dispersal mutualism common in deciduous forests of eastern North America. As climatic warming alters the abundance and activity levels of ants, the potential exists for shifts in rates of ant-mediated seed dispersal. We used an experimental temperature manipulation at two sites in the eastern US (Harvard Forest in Massachusetts and Duke Forest in North Carolina) to examine the potential impacts of climatic warming on overall rates of seed dispersal (using Asarum canadense seeds) as well as species-specific rates of seed dispersal at the Duke Forest site. We also examined the relationship between ant critical thermal maxima (CTmax) and the mean seed removal temperature for each ant species. We found that seed removal rates did not change as a result of experimental warming at either study site, nor were there any changes in species-specific rates of seed dispersal. There was, however, a positive relationship between CTmax and mean seed removal temperature, whereby species with higher CTmax removed more seeds at hotter temperatures. The temperature at which seeds were removed was influenced by experimental warming as well as diurnal and day-to-day fluctuations in temperature. Taken together, our results suggest that while temperature may play a role in regulating seed removal by ants, ant plant seed-dispersal mutualisms may be more robust to climate change than currently assumed. PMID:24688863

Removal of copper(II) from some environmental samples by sorptive-flotation using powdered marble wastes as sorbents and oleic acid as surfactant.

PubMed

Ghazy, S E; Samra, S E; Mahdy, A F M; El-Morsy, S M

2004-11-01

A simple and economic experimental sorptive -flotation procedure is presented for the removal of copper(II) species from aqueous solutions. It is based on using powdered marble wastes (PMW), which are widespread and inexpensive and may represent an environmental problem, as the effective inorganic sorbent and oleic (HOL) as the surfactant. The main parameters (i.e. initial solution pH, sorbent, surfactant and copper concentrations, stirring times, ionic strength, temperature and the presence of foreign ions) influencing the flotation of PMW and /or Cu(II) were examined. Nearly, 100% of PMW and Cu(II) were removed from aqueous solutions at pH7 after stirring for 10 min and at room temperature, (approximately 25 degrees C). The procedure was successfully applied to recover Cu(II) spiked to some natural water samples. A mechanism for sorption and flotation is suggested.

Computational study of ibuprofen removal from water by adsorption in realistic activated carbons.

PubMed

Bahamon, Daniel; Carro, Leticia; Guri, Sonia; Vega, Lourdes F

2017-07-15

Molecular simulations using the Grand Canonical Monte Carlo (GCMC) method have been performed in order to obtain physical insights on how the interaction between ibuprofen (IBP) and activated carbons (ACs) in aqueous mixtures affects IBP removal from water by ACs. A nanoporous carbon model based on units of polyaromatic molecules with different number of rings, defects and polar-oxygenated sites is described. Individual effects of factors such as porous features and chemical heterogeneities in the adsorbents are investigated and quantified. Results are in good agreement with experimental adsorption data, highlightening the ability of GCMC simulation to describe the macroscopic adsorption performance in drug removal applications, while also providing additional insights into the IBP/water adsorption mechanism. The simulation results allow finding the optimal type of activated carbon material for separating this pollutant in water treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Treatment of antibiotic fermentation wastewater by combined polyferric sulfate coagulation, Fenton and sedimentation process.

PubMed

Xing, Zi-Peng; Sun, De-Zhi

2009-09-15

Attempts were made in this study to examine the combined polyferric sulfate (PFS) coagulation, Fenton and sedimentation process for treatment of non-degradable antibiotic fermentation wastewater. The experimental results indicated that 66.6% of color and 72.4% of chemical oxygen demand (COD) were removed under the optimum conditions of PFS dosage 200mg/L and pH 4.0. In addition, optimal parameters of Fenton process were determined to be 150 mg/L of H(2)O(2) dosage, 120 mg/L of FeSO(4) and 1h of reaction time. When Fenton treated effluent was controlled at pH 7.0, the pollutants could be further removed by sedimentation process. The overall color, COD and suspended solids (SS) removal reached 97.3%, 96.9% and 86.7% under selected conditions, respectively. Thus this study might offer an effective way for wastewater treatment of antibiotics manufacturer and pharmaceutical industry.

Automatic specular reflections removal for endoscopic images

NASA Astrophysics Data System (ADS)

Tan, Ke; Wang, Bin; Gao, Yuan

2017-07-01

Endoscopy imaging is utilized to provide a realistic view about the surfaces of organs inside the human body. Owing to the damp internal environment, these surfaces usually have a glossy appearance showing specular reflections. For many computer vision algorithms, the highlights created by specular reflections may become a significant source of error. In this paper, we present a novel method for restoration of the specular reflection regions from a single image. Specular restoration process starts with generating a substitute specular-free image with RPCA method. Then the specular removed image was obtained by taking the binary weighting template of highlight regions as the weighting for merging the original specular image and the substitute image. The modified template was furthermore discussed for the concealment of artificial effects in the edge of specular regions. Experimental results on the removal of the endoscopic image with specular reflections demonstrate the efficiency of the proposed method comparing to the existing methods.

Removal of toxic Cr(VI) ions from tannery industrial wastewater using a newly designed three-phase three-dimensional electrode reactor

NASA Astrophysics Data System (ADS)

Grace Pavithra, K.; Senthil Kumar, P.; Carolin Christopher, Femina; Saravanan, A.

2017-11-01

In this research, the wastewater samples were collected from leather tanning industry at different time intervals. The parameters like pH, electrical conductivity, temperature, turbidity, chromium and chemical oxygen demand (COD) of the samples were analyzed. A three-phase three-dimensional fluidized type electrode reactor (FTER) was newly designed for the effective removal of toxic pollutants from wastewater. The influencing parameters were optimized for the maximum removal of toxic pollutants from wastewater. The optimum condition for the present system was calculated as: contact time of 30 min, applied voltage of 3 V and the particle electrodes of 15 g. The particle electrode was characterized by using FT-IR analysis. Langmuir-Hinshelwood and pseudo-second order kinetic models were fits well with the experimental data. The results showed that the FTER can be successfully employed for the treatment of industrial wastewater.

Scattering Removal for Finger-Vein Image Restoration

PubMed Central

Yang, Jinfeng; Zhang, Ben; Shi, Yihua

2012-01-01

Finger-vein recognition has received increased attention recently. However, the finger-vein images are always captured in poor quality. This certainly makes finger-vein feature representation unreliable, and further impairs the accuracy of finger-vein recognition. In this paper, we first give an analysis of the intrinsic factors causing finger-vein image degradation, and then propose a simple but effective image restoration method based on scattering removal. To give a proper description of finger-vein image degradation, a biological optical model (BOM) specific to finger-vein imaging is proposed according to the principle of light propagation in biological tissues. Based on BOM, the light scattering component is sensibly estimated and properly removed for finger-vein image restoration. Finally, experimental results demonstrate that the proposed method is powerful in enhancing the finger-vein image contrast and in improving the finger-vein image matching accuracy. PMID:22737028

Cadmium removal in a biosorption column

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

Volesky, B.; Prasetyo, I.

New biosorbent material derived from a ubiquitous brown marine alga Ascophyllum nodosum has been examined in packed-bed flow-through sorption columns. It effectively removed 10 mg/L of cadmium down to 1.5 ppb levels in the effluent, representing 99.985% removal. The experimental methodology used was based on the early Bohart and Adams sorption model, resulting in quantitative determination of the characteristic process parameters which can be used for performance comparison and process design. An average metal loading of the biosorbent (N[sub 0]) determined was 30 mg Cd/g, corresponding closely to that observed for the batch equilibrium metal concentration of 10 mg Cd/L.more » The critical bed depth (D[sub min]) for the potable water effluent quality standard varied with the column feed flow rate from 20 to 50 cm. The sorption column mass transfer and dispersion coefficients were determined, which are also required for solving the sorption model equations.« less

The thermodynamic properties of benzothiazole and benzoxazole

NASA Astrophysics Data System (ADS)

Steele, W. V.; Chirico, R. D.; Knipmeyer, S. E.; Nguyen, A.

1991-08-01

This research program, funded by the Department of Energy, Office of Fossil Energy, Advanced Extraction and Process Technology, provides accurate experimental thermochemical and thermophysical properties for key organic diheteroatom-containing compounds present in heavy petroleum feedstocks, and applies the experimental information to thermodynamic analyses of key hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation reaction networks. Thermodynamic analyses, based on accurate information, provide insights for the design of cost-effective methods of heteroatom removal. The results reported here, and in a companion report to be completed, will point the way to the development of new methods of heteroatom removal from heavy petroleum. Measurements leading to the calculation of the ideal-gas thermodynamic properties are reported for benzothiazole and benzoxazole. Experimental methods included combustion calorimetry, adiabatic heat-capacity calorimetry, comparative ebulliometry, inclinded-piston gauge manometry, and differential-scanning calorimetry (d.s.c). Critical property estimates are made for both compounds. Entropies, enthalpies, and Gibbs energies of formation were derived for the ideal gas for both compounds for selected temperatures between 280 K and near 650 K. The Gibbs energies of formation will be used in a subsequent report in thermodynamic calculations to study the reaction pathways for the removal of the heteratoms by hydrogenolysis. The results obtained in this research are compared with values present in the literature. The failure of a previous adiabatic heat capacity study to see the phase transition in benzothiazole is noted. Literature vibrational frequency assignments were used to calculate ideal gas entropies in the temperature range reported here for both compounds. Resulting large deviations show the need for a revision of those assignments.

High Resilience of Seed Dispersal Webs Highlighted by the Experimental Removal of the Dominant Disperser.

PubMed

Timóteo, Sérgio; Ramos, Jaime Albino; Vaughan, Ian Phillip; Memmott, Jane

2016-04-04

The pressing need to conserve and restore habitats in the face of ongoing species loss [1, 2] requires a better understanding of what happens to communities when species are lost or reinstated [3, 4]. Theoretical models show that communities are relatively insensitive to species loss [5, 6]; however, they disagree with field manipulations showing a cascade of extinctions [7, 8] and have seldom been tested under field conditions (e.g., [9]). We experimentally removed the most abundant seed-dispersing ant species from seed dispersal networks in a Mediterranean landscape, replicating the experiment in three types of habitat, and then compared these communities to un-manipulated control communities. Removal did not result in large-scale changes in network structure. It revealed extensive structural plasticity of the remaining community, which rearranged itself through rewiring, while maintaining its functionality. The remaining ant species widened their diet breadth in a way that maintained seed dispersal, despite the identity of many interactions changing. The species interaction strength decreased; thus, the importance of each ant species for seed dispersal became more homogeneous, thereby reducing the dependence of seed species on one dominant ant species. Compared to the experimental results, a simulation model that included rewiring considerably overestimated the effect of species loss on network robustness. If community-level species loss models are to be of practical use in ecology or conservation, they need to include behavioral and population responses, and they need to be routinely tested under field conditions; doing this would be to the advantage of both empiricists and theoreticians. Copyright © 2016 Elsevier Ltd. All rights reserved.

The kinetics of lactate production and removal during whole-body exercise

PubMed Central

2012-01-01

Background Based on a literature review, the current study aimed to construct mathematical models of lactate production and removal in both muscles and blood during steady state and at varying intensities during whole-body exercise. In order to experimentally test the models in dynamic situations, a cross-country skier performed laboratory tests while treadmill roller skiing, from where work rate, aerobic power and blood lactate concentration were measured. A two-compartment simulation model for blood lactate production and removal was constructed. Results The simulated and experimental data differed less than 0.5 mmol/L both during steady state and varying sub-maximal intensities. However, the simulation model for lactate removal after high exercise intensities seems to require further examination. Conclusions Overall, the simulation models of lactate production and removal provide useful insight into the parameters that affect blood lactate response, and specifically how blood lactate concentration during practical training and testing in dynamical situations should be interpreted. PMID:22413898

Electrolytic ammonia removal and current efficiency by a vermiculite-packed electrochemical reactor

PubMed Central

Li, Liang; Yao, Ji; Fang, Xueyou; Huang, Yuanxing; Mu, Yan

2017-01-01

The ammonia removal as well as the current efficiency during electrolysis was investigated by using a vermiculite-packed electrochemical reactor under continuous mode. Experimental results showed that adsorption of ammonia by vermiculite and electrolytic desorption of ammonia simultaneously existed in the reactor, leading to 89% removal of initial 30 mg N/L ammonia and current efficiency of 25% under the condition of 2.0 A, 6.0 min hydraulic retention time with 300 mg Cl/L chloride as the catalyst. The ammonia removal capacity had a linear relationship with the products of hydraulic retention time, current and chloride concentration within experimental conditions. The treatment results of secondary effluent indicated that 29.9 mg N/L ammonia can be reduced to 4.6 mg N/L with 72% removal of total nitrogen and a current efficiency of 23%, which was 2% less than synthetic wastewater due to the reducing components in the real wastewater. PMID:28102340

Removal Rate Model for Magnetorheological Finishing of Glass

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

DeGroote, J.E.; Marino, A.E.; WIlson, J.P.

2007-11-14

Magnetorheological finishing (MRF) is a deterministic subaperture polishing process. The process uses a magntorheological (MR) fluid that consists of micrometer-sized, spherical, magnetic carbonyl iron (CI) particles, nonmagnetic polishing abrasives, water, and stabilizers. Material removal occurs when the CI and nonmagnetic polishing abrasives shear material off the surface being polished. We introduce a new MRF material removal rate model for glass. This model contains terms for the near surface mechanical properties of glass, drag force, polishing abrasive size and concentration, chemical durability of the glass, MR fluid pH, and the glass composition. We introduce quantitative chemical predictors for the first time,more » to the best of our knowledge, into an MRF removal rate model. We validate individual terms in our model separately and then combine all of the terms to show the whole MRF material removal model compared with experimental data. All of our experimental data were obtained using nanodiamond MR fluids and a set of six optical glasses.« less

Addressing Antibiotic Abuse in China: An Experimental Audit Study☆

PubMed Central

Currie, Janet; Lin, Wanchuan; Meng, Juanjuan

2016-01-01

China has high rates of antibiotic abuse and antibiotic resistance but the causes are still a matter for debate. Strong physician financial incentives to prescribe are likely to be an important cause. However, patient demand (or physician beliefs about patient demand) is often cited and may also play a role. We use an audit study to examine the effect of removing financial incentives, and to try to separate out the effects of patient demand. We implement a number of different experimental treatments designed to try to rule out other possible explanations for our findings. Together, our results suggest that financial incentives are the main driver of antibiotic abuse in China, at least in the young and healthy population we draw on in our study. PMID:26949284

Experimental study of hydraulics and sediment capture efficiency in catchbasins.

PubMed

Tang, Yangbo; Zhu, David Z; Rajaratnam, N; van Duin, Bert

2016-12-01

Catchbasins (also known as gully pot in the UK and Australia) are used to receive surface runoff and drain the stormwater into storm sewers. The recent interest in catchbasins is to improve their effectiveness in removing sediments in stormwater. An experimental study was conducted to examine the hydraulic features and sediment capture efficiency in catchbasins, with and without a bottom sump. A sump basin is found to increase the sediment capture efficiency significantly. The effect of inlet control devices, which are commonly used to control the amount of flow into the downstream storm sewer system, is also studied. These devices will increase the water depth in the catchbasin and increase the sediment capture efficiency. Equations are developed for predicting the sediment capture efficiency in catchbasins.

Effect of Tris-acetate buffer on endotoxin removal from human-like collagen used biomaterials.

PubMed

Zhang, Huizhi; Fan, Daidi; Deng, Jianjun; Zhu, Chenghui; Hui, Junfeng; Ma, Xiaoxuan

2014-09-01

Protein preparation, which has active ingredients designated for the use of biomaterials and therapeutical protein, is obtained by genetic engineering, but products of genetic engineering are often contaminated by endotoxins. Because endotoxin is a ubiquitous and potent proinflammatory agent, endotoxin removal or depletion from protein is essential for researching any biomaterials. In this study, we have used Tris-acetate (TA) buffer of neutral pH value to evaluate endotoxins absorbed on the Pierce high-capacity endotoxin removal resin. The effects of TA buffer on pH, ionic strength, incubation time as well as human-like collagen (HLC) concentration on eliminating endotoxins are investigated. In the present experiments, we design an optimal method for TA buffer to remove endotoxin from recombinant collagen and use a chromogenic tachypleus amebocyte lysate (TAL) test kit to measure the endotoxin level of HLC. The present results show that, the endotoxins of HLC is dropped to 8.3EU/ml at 25 mM TA buffer (pH7.8) with 150 mM NaCl when setting incubation time at 6h, and HLC recovery is about 96%. Under this experimental condition, it is proved to exhibit high efficiencies of both endotoxin removal and collagen recovery. The structure of treated HLC was explored by Transmission Electron Microscopy (TEM), demonstrating that the property and structure of HLC treated by TA buffer are maintained. Compared to the most widely used endotoxin removal method, Triton X-114 extraction, using TA buffer can obtain the non-toxic HLC without extra treatment for removing the toxic substances in Triton X-114. In addition, the present study aims at establishing a foundation for further work in laboratory animal science and providing a foundation for medical grade biomaterials. Copyright © 2014 Elsevier B.V. All rights reserved.

Detection of density dependence requires density manipulations and calculation of lambda.

PubMed

Fowler, N L; Overath, R Deborah; Pease, Craig M

2006-03-01

To investigate density-dependent population regulation in the perennial bunchgrass Bouteloua rigidiseta, we experimentally manipulated density by removing adults or adding seeds to replicate quadrats in a natural population for three annual intervals. We monitored the adjacent control quadrats for 14 annual intervals. We constructed a population projection matrix for each quadrat in each interval, calculated lambda, and did a life table response experiment (LTRE) analysis. We tested the effects of density upon lambda by comparing experimental and control quadrats, and by an analysis of the 15-year observational data set. As measured by effects on lambda and on N(t+1/Nt in the experimental treatments, negative density dependence was strong: the population was being effectively regulated. The relative contributions of different matrix elements to treatment effect on lambda differed among years and treatments; overall the pattern was one of small contributions by many different life cycle stages. In contrast, density dependence could not be detected using only the observational (control quadrats) data, even though this data set covered a much longer time span. Nor did experimental effects on separate matrix elements reach statistical significance. These results suggest that ecologists may fail to detect density dependence when it is present if they have only descriptive, not experimental, data, do not have data for the entire life cycle, or analyze life cycle components separately.

Removal of sulphur-containing odorants from fuel gases for fuel cell-based combined heat and power applications

NASA Astrophysics Data System (ADS)

de Wild, P. J.; Nyqvist, R. G.; de Bruijn, F. A.; Stobbe, E. R.

Natural gas (NG) and liquefied petroleum gas (LPG) are important potential feedstocks for the production of hydrogen for fuel cell-based (e.g. proton exchange membrane fuel cells (PEMFC) or solid oxide fuel Cells (SOFC) combined heat and power (CHP) applications. To prevent detrimental effects on the (electro)catalysts in fuel cell-based combined heat and power installations (FC-CHP), sulphur removal from the feedstock is mandatory. An experimental bench-marking study of adsorbents has identified several candidates for the removal of sulphur containing odorants at low temperature. Among these adsorbents a new material has been discovered that offers an economically attractive means to remove TetraHydroThiophene (THT), the main European odorant, from natural gas at ambient temperature. The material is environmentally benign, easy to use and possesses good activity (residual sulphur levels below 20 ppbv) and capacity for the common odorant THT in natural gas. When compared to state-of-the-art metal-promoted active carbon the new material has a THT uptake capacity that is up to 10 times larger, depending on temperature and pressure. Promoted versions of the new material have shown potential for the removal of THT at higher temperatures and/or for the removal of other odorants such as mercaptans from natural gas or from LPG.

Experiments of eliminating the destructive effects of excessive Fe inclusions for Al secondary products

NASA Astrophysics Data System (ADS)

Sun, D. Q.; Dai, G. H.; Geng, F.; Yang, K.

2017-02-01

Excessive Fe content in Al alloys caused the serious decline of mechanical properties, such as the ductility and impact toughness. Carried out the experiments of eliminating the destructive effects of excessive Fe content by flux-adding technology, which including removing a part of Fe content from Al scrap melt and modifying the morphology of Fe rich precipitates. The experimental results showed that, the ratio of removing Fe element was above 20%, and the morphology of Fe rich precipitates changed from Lamellar to bulk or lath precipitations under the process parameters: the fluxing-agents composed of borax, and MnCl2 (mixed by mass ratio of 1:1), and the adding amount of fluxing-agents was about 1.5%; thrown the fluxing-agents into the Al scrap melt by powder injection process and kept for 30 min.

Biofiltration of air polluted with toluene under steady-state conditions: Experimental observations

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

Kiared, K.; Fundenberger, B.; Brzezinski, R.

1997-11-01

In this study, the authors describe the removal of toluene vapors in a pilot scale biofilter. Biofiltration tests have been performed in a column fed upward with contaminated air at ambient conditions. The column was packed with a mixture of conditioned biomass and structuring agent on which a mixed microbial population of four selected strains was immobilized and then formed a biolayer. The biofilter was operated under various inlet-airstream toluene concentrations and flow rates of the contaminated airstream. Based on the present measurements, the biofilter proved effective in removing toluene at rates up to 165 g/h {center_dot} m{sup 3} ofmore » packing. The effect of some design and operation parameters (concentration of nutrients solution, presence of xylene, gas flow rate, pressure drop, temperature, etc.) are reported.« less

Enhancement of total nitrogen removal through effluent recirculation and fate of PPCPs in a hybrid constructed wetland system treating urban wastewater.

PubMed

Ávila, Cristina; Pelissari, Catiane; Sezerino, Pablo H; Sgroi, Massimiliano; Roccaro, Paolo; García, Joan

2017-04-15

The effect of effluent recirculation on the removal of total nitrogen (TN) and eight pharmaceuticals and personal care products (PPCPs) was evaluated during 9months in an experimental hybrid constructed wetland (CW) system applied in the treatment of urban wastewater. An Imhoff tank was followed by three stages of CWs (two 1.5-m 2 vertical subsurface flow (VF) beds alternating feed-rest cycles, a 2-m 2 horizontal (HF) and a 2-m 2 free water surface (FWS) wetland in series). A fraction of the final effluent was recycled back to the Imhoff tank with a recirculation rate of 50% (hydraulic loading rate=0.37md -1 ). The system's performance varied throughout the study. In Period I (summer) consistently high load removal efficiencies of TN (89±5%) and a removal rate of 6.6±1.4gTNm -2 d -1 were exhibited. In Period II (fall), the poor performance of the FWS during the senescence of macrophytes caused a large increase in organic matter, solids and nutrient concentrations, drastically deteriorating water quality. The determination of PPCPs was conducted during this period. Recalcitrant compounds, namely sulfamethoxazole, carbamazapine, TCEP and sucralose were negligibly removed in all CWs. However, noteworthy was the ≈30% removal of sucralose in the VF wetland. Caffeine (80%) and fluoxetine (27%) showed similar elimination rates in both VF and HF units, whereas trimethoprim and DEET were significantly better removed in the VF than in the HF. The concentration of the four latter compounds showed a severe increase in the FWS, indicating possible desorption from the sediment/biomass during adverse conditions. Harvesting of the aboveground biomass in this unit returned the system's performance back to normality (Period III), achieving 77±7% TN removal despite the winter season, proving effluent recirculation as an effective strategy for TN removal in hybrid CW systems when stringent restrictions are in place. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of missing data on multitask prediction methods.

PubMed

de la Vega de León, Antonio; Chen, Beining; Gillet, Valerie J

2018-05-22

There has been a growing interest in multitask prediction in chemoinformatics, helped by the increasing use of deep neural networks in this field. This technique is applied to multitarget data sets, where compounds have been tested against different targets, with the aim of developing models to predict a profile of biological activities for a given compound. However, multitarget data sets tend to be sparse; i.e., not all compound-target combinations have experimental values. There has been little research on the effect of missing data on the performance of multitask methods. We have used two complete data sets to simulate sparseness by removing data from the training set. Different models to remove the data were compared. These sparse sets were used to train two different multitask methods, deep neural networks and Macau, which is a Bayesian probabilistic matrix factorization technique. Results from both methods were remarkably similar and showed that the performance decrease because of missing data is at first small before accelerating after large amounts of data are removed. This work provides a first approximation to assess how much data is required to produce good performance in multitask prediction exercises.

An ecological vegetation-activated sludge process (V-ASP) for decentralized wastewater treatment: system development, treatment performance, and mathematical modeling.

PubMed

Yuan, Jiajia; Dong, Wenyi; Sun, Feiyun; Li, Pu; Zhao, Ke

2016-05-01

An environment-friendly decentralized wastewater treatment process that is comprised of activated sludge process (ASP) and wetland vegetation, named as vegetation-activated sludge process (V-ASP), was developed for decentralized wastewater treatment. The long-term experimental results evidenced that the vegetation sequencing batch reactor (V-SBR) process had consistently stable higher removal efficiencies of organic substances and nutrients from domestic wastewater compared with traditional sequencing batch reactor (SBR). The vegetation allocated into V-SBR system could not only remove nutrients through its vegetation transpiration ratio but also provide great surface area for microorganism activity enhancement. This high vegetation transpiration ratio enhanced nutrients removal effectiveness from wastewater mainly by flux enhancement, oxygen and substrate transportation acceleration, and vegetation respiration stimulation. A mathematical model based on ASM2d was successfully established by involving the specific function of vegetation to simulate system performance. The simulation results on the influence of operational parameters on V-ASP treatment effectiveness demonstrated that V-SBR had a high resistance to seasonal temperature fluctuations and influent loading shocking.

Rapid small-scale column testing of granular activated carbon for organic micro-pollutant removal in treated domestic wastewater.

PubMed

Zietzschmann, F; Müller, J; Sperlich, A; Ruhl, A S; Meinel, F; Altmann, J; Jekel, M

2014-01-01

This study investigates the applicability of the rapid small-scale column test (RSSCT) concept for testing of granular activated carbon (GAC) for organic micro-pollutants (OMPs) removal from wastewater treatment plant (WWTP) effluent. The chosen experimental setup was checked using pure water, WWTP effluent, different GAC products, and variable hydrodynamic conditions with different flow velocities and differently sized GAC, as well as different empty bed contact times (EBCTs). The setup results in satisfying reproducibility and robustness. RSSCTs in combination with WWTP effluent are effective when comparing the OMP removal potentials of different GAC products and are a useful tool for the estimation of larger filters. Due to the potentially high competition between OMPs and bulk organics, breakthrough curves are likely to have unfavorable shapes when treating WWTP effluent. This effect can be counteracted by extending the EBCT. With respect to the strong competition observed in GAC treatment of WWTP effluent, the small organic acid and neutral substances are retained longer in the RSSCT filters and are likely to cause the majority of the observed adsorption competition with OMPs.

Trace contaminant studies of HSC adsorbent. M.S. Thesis

NASA Technical Reports Server (NTRS)

Yieh, D. T. N.

1978-01-01

The adsorption and desorption of fifteen trace contaminants on HSC (polyethylenimine coated acrylic ester) adsorbent were experimentally investigated with the following two objectives: to test the removal potential and the adsorption reversibility of the selected trace contaminants, and to test the effect a preadsorbed trace contaminant has on the CO2 adsorption capacity. The experimental method for acquiring the adsorption equilibrium data used is based on the volumetric (or displacement) concept of vacuum adsorption. From the experimental results, it was found that the HSC adsorbent has good adsorption potential for contaminants of alcohol compounds, esters, and benzene compounds; whereas, adsorption of ketone compounds, oxidizing and reducing agents are detrimental to the adsorbent. In addition, all liquid contaminants reduce the CO2 capacity of HSC adsorbent.

Complexing agent and heavy metal removals from metal plating effluent by electrocoagulation with stainless steel electrodes.

PubMed

Kabdaşli, Işik; Arslan, Tülin; Olmez-Hanci, Tuğba; Arslan-Alaton, Idil; Tünay, Olcay

2009-06-15

In the present study, the treatability of a metal plating wastewater containing complexed metals originating from the nickel and zinc plating process by electrocoagulation using stainless steel electrodes was experimentally investigated. The study focused on the effect of important operation parameters on electrocoagulation process performance in terms of organic complex former, nickel and zinc removals as well as sludge production and specific energy consumption. The results indicated that increasing the applied current density from 2.25 to 9.0 mA/cm(2) appreciably enhanced TOC removal efficiency from 20% to 66%, but a further increase in the applied current density to 56.25 mA/cm(2) did not accelerate TOC removal rates. Electrolyte concentration did not affect the process performance significantly and the highest TOC reduction (66%) accompanied with complete heavy metal removals were achieved at the original chloride content ( approximately 1500 mg Cl/L) of the wastewater sample. Nickel removal performance was adversely affected by the decrease of initial pH from its original value of 6. Optimum working conditions for electrocoagulation of metal plating effluent were established as follows: an applied current density of 9 mA/cm(2), the effluent's original electrolyte concentration and pH of the composite sample. TOC removal rates obtained for all electrocoagulation runs fitted pseudo-first-order kinetics very well (R(2)>92-99).

A modified UCT method for biological nutrient removal: configuration and performance.

PubMed

Vaiopoulou, E; Aivasidis, A

2008-07-01

A pilot-scale prototype activated sludge system is presented, which combines both, the idea of University of Cape Town (UCT) concept and the step denitrification cascade for removal of carbon, nitrogen and phosphorus. The experimental set-up consists of an anaerobic selector and stepwise feeding in subsequent three identical pairs of anoxic and oxic tanks. Raw wastewater with influent flow rates ranging between 48 and 168 l d(-1) was fed to the unit at hydraulic residence times (HRTs) of 5-18 h and was distributed at percentages of 60/25/15%, 40/30/30% and 25/40/35% to the anaerobic selector, 2nd and 3rd anoxic tanks, respectively (influent flow distribution before the anaerobic selector). The results for the entire experimental period showed high removal efficiencies of organic matter of 89% as total chemical oxygen demand removal and 95% removal for biochemical oxygen demand, 90% removal of total Kjeldahl nitrogen and total nitrogen removal through denitrification of 73%, mean phosphorus removal of 67%, as well as excellent settleability. The highest removal efficiency and the optimum performance were recorded at an HRT of about 9h and influent flow rate of 96 l d(-1), in which 60% is distributed to the anaerobic selector, 25% to the second anoxic tank and 15% to the last anoxic tank. Consequently, the plant configuration enhanced removal efficiency, optimized performance, saved energy, formed good settling sludge and provided operational assurance.

Enhanced methane production from pig slurry with pulsed electric field pre-treatment.

PubMed

Safavi, Seyedeh Masoumeh; Unnthorsson, Runar

2018-02-01

Intensive amount of manure produced in pig breeding sectors represents negative impact on the environment and requires optimal management. Anaerobic digestion as a well-known manure management process was optimized in this experimental study by pulsed electric field (PEF) pre-treatment. The effect of PEF on methane production was investigated at three different intensities (15, 30 and 50 kWh/m 3 ). The results indicate that the methane production and chemical oxygen demand (COD) removal was improved by continuous escalation of applied intensity, up to 50 kWh/m 3 . In comparison with untreated slurry, methane production and COD removal were increased up to 58% and 44%, respectively.

The dependence of the CO2 removal efficiency of LiOH on humidity and mesh size. [in spacecraft life support systems

NASA Technical Reports Server (NTRS)

Davis, S. H.; Kissinger, L. D.

1978-01-01

The effect of humidity on the CO2 removal efficiency of small beds of anhydrous LiOH has been studied. Experimental data taken in this small bed system clearly show that there is an optimum humidity for beds loaded with LiOH from a single lot. The CO2 efficiency falls rapidly under dry conditions, but this behavior is approximately the same in all samples. The behavior of the bed under wet conditions is quite dependent on material size distribution. The presence of large particles in a sample can lead to rapid fall off in the CO2 efficiency as the humidity increases.

II. Electrodeposition/removal of nickel in a spouted electrochemical reactor

PubMed Central

Grimshaw, Pengpeng; Calo, Joseph M.; Shirvanian, Pezhman A.; Hradil, George

2011-01-01

An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well. PMID:22039317

Effect of experimental manipulation on survival and recruitment of feral pigs

USGS Publications Warehouse

Hanson, L.B.; Mitchell, M.S.; Grand, J.B.; Jolley, D.B.; Sparklin, B.D.; Ditchkoff, S.S.

2009-01-01

Lethal removal is commonly used to reduce the density of invasive-species populations, presuming it reduces population growth rate; the actual effect of lethal removal on the vital rates contributing to population growth, however, is rarely tested. We implemented a manipulative experiment of feral pig (Sus scrofa) populations at Fort Benning, Georgia, USA, to assess the demographic effects of harvest intensity. Using markrecapture data, we estimated annual survival, recruitment, and population growth rates of populations in a moderately harvested area and a heavily harvested area for 200406. Population growth rates did not differ between the populations. The top-ranked model for survival included a harvest intensity effect; model-averaged survival was lower for the heavily harvested population than for the moderately harvested population. Increased immigration and reproduction likely compensated for the increased mortality in the heavily harvested population. We conclude that compensatory responses in feral pig recruitment can limit the success of lethal control efforts. ?? 2009 CSIRO.

Elastic scattering spectroscopy for detection of cancer risk in Barrett's esophagus: experimental and clinical validation of error removal by orthogonal subtraction for increasing accuracy

NASA Astrophysics Data System (ADS)

Zhu, Ying; Fearn, Tom; MacKenzie, Gary; Clark, Ben; Dunn, Jason M.; Bigio, Irving J.; Bown, Stephen G.; Lovat, Laurence B.

2009-07-01

Elastic scattering spectroscopy (ESS) may be used to detect high-grade dysplasia (HGD) or cancer in Barrett's esophagus (BE). When spectra are measured in vivo by a hand-held optical probe, variability among replicated spectra from the same site can hinder the development of a diagnostic model for cancer risk. An experiment was carried out on excised tissue to investigate how two potential sources of this variability, pressure and angle, influence spectral variability, and the results were compared with the variations observed in spectra collected in vivo from patients with Barrett's esophagus. A statistical method called error removal by orthogonal subtraction (EROS) was applied to model and remove this measurement variability, which accounted for 96.6% of the variation in the spectra, from the in vivo data. Its removal allowed the construction of a diagnostic model with specificity improved from 67% to 82% (with sensitivity fixed at 90%). The improvement was maintained in predictions on an independent in vivo data set. EROS works well as an effective pretreatment for Barrett's in vivo data by identifying measurement variability and ameliorating its effect. The procedure reduces the complexity and increases the accuracy and interpretability of the model for classification and detection of cancer risk in Barrett's esophagus.

Photo-Fenton degradation of phenol, 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenol mixture in saline solution using a falling-film solar reactor.

PubMed

Luna, Airton J; Nascimento, Cláudio A O; Foletto, Edson Luiz; Moraes, José E F; Chiavone-Filhoe, Osvaldo

2014-01-01

In this work, a saline aqueous solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a falling-film solar reactor. The influence of the parameters such as initial pH (5-7), initial concentration of Fe2+ (1-2.5mM) and rate of H202 addition (1.87-3.74mmol min-1) was investigated. The efficiency of photodegradation was determined from the removal of dissolved organic carbon (DOC), described by the species degradation of phenol, 2,4-D and 2,4-DCP. Response surface methodology was employed to assess the effects of the variables investigated, i.e. [Fe2+], [H202] and pH, in the photo-Fenton process with solar irradiation. The results reveal that the variables' initial concentration of Fe2+ and H202 presents predominant effect on pollutants' degradation in terms of DOC removal, while pH showed no influence. Under the most adequate experimental conditions, about 85% DOC removal was obtained in 180 min by using a reaction system employed here, and total removal of phenol, 2,4- and 2,4-DCP mixture in about 30min.

Engineered nano-magnetic iron oxide-urea-activated carbon nanolayer sorbent for potential removal of uranium (VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Mahmoud, Mohamed E.; Khalifa, Mohamed A.; El Wakeel, Yasser M.; Header, Mennatllah S.; Abdel-Fattah, Tarek M.

2017-04-01

A novel magnetic nanosorbent was designed using chemical grafting of nano-magnetite (Nano-Fe3O4) with nanolayer of activated carbon (AC) via urea intermediate for the formation of Nano-Fe3O4-Urea-AC. Characterizing was carried out using FT-IR, SEM, HR-TEM, TGA, point of zero charge (Pzc) and surface area analysis. The designed sorbent maintained its magnetic properties and nanosized structure in the range of 8.7-14.1 nm. The surface area was identified as 389 m2/g based on the BET method. Sorption of uranyl ions from aqueous solutions was studied and evaluated in different experimental conditions. Removal of uranyl ions increased with increasing in pH value and the maximum percentage removal was established at pH 5.0. The removal and sorption processes of uranyl ions by Nano-Fe3O4-Urea-AC sorbent were studied and optimized using the batch technique. The key variables affecting removal of uranyl ions were studied including the effect of the contact time, dosage of Nano-Fe3O4-Urea-AC sorbent, reaction temperature, initial uranyl ions concentration and interfering anions and cations.

Investigations into the mechanism of material removal and surface modification at atomic scale on stainless steel using molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Ranjan, Prabhat; Balasubramaniam, R.; Jain, V. K.

2018-06-01

A molecular dynamics simulation (MDS) has been carried out to investigate the material removal phenomenon of chemo-mechanical magnetorheological finishing (CMMRF) process. To understand the role of chemical assisted mechanical abrasion in CMMRF process, material removal phenomenon is subdivided into three different stages. In the first stage, new atomic bonds viz. Fe-O-Si is created on the surface of the workpiece (stainless steel). The second stage deals with the rupture of parent bonds like Fe-Fe on the workpiece. In the final stage, removal of material from the surface in the form of dislodged debris (cluster of atoms) takes place. Effects of process parameters like abrasive particles, depth of penetration and initial surface condition on finishing force, potential energy (towards secondary phenomenon such as chemical instability of the finished surface) and material removal at atomic scale have been investigated. It was observed that the type of abrasive particle is one of the important parameters to produce atomically smooth surface. Experiments were also conducted as per the MDS to generate defect-free and sub-nanometre-level finished surface (Ra value better than 0.2 nm). The experimental results reasonably agree well with the simulation results.

[Removal of toluene from waste gas by honeycomb adsorption rotor with modified 13X molecular sieves].

PubMed

Wang, Jia-De; Zheng, Liang-Wei; Zhu, Run-Ye; Yu, Yun-Feng

2013-12-01

The removal of toluene from waste gas by Honeycomb Adsorption Rotor with modified 13X molecular sieves was systematically investigated. The effects of the rotor operating parameters and the feed gas parameters on the adsorption efficiency were clarified. The experimental results indicated that the honeycomb adsorption rotor had a good humidity resistance. The removal efficiency of honeycomb adsorption rotor achieved the maximal value with optimal rotor speed and optimal generation air temperature. Moreover, for an appropriate flow rate ratio the removal efficiency and energy consumption should be taken into account. When the recommended operating parameters were regeneration air temperature of 180 degrees C, rotor speed of 2.8-5 r x h(-1), flow rate ratio of 8-12, the removal efficiency kept over 90% for the toluene gas with concentration of 100 mg x m(-3) and inlet velocity of 2 m x s(-1). The research provided design experience and operating parameters for industrial application of honeycomb adsorption rotor. It showed that lower empty bed velocity, faster rotor speed and higher temperature were necessary to purify organic waste gases of higher concentrations.

Removal of polycyclic aromatic hydrocarbons from soil: a comparison between bioremoval and supercritical fluids extraction.

PubMed

Amezcua-Allieri, M A; Ávila-Chávez, M A; Trejo, A; Meléndez-Estrada, J

2012-03-01

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic substances which are resistant to environmental degradation due to their highly hydrophobic nature. Soils contaminated with PAHs pose potential risks to human and ecological health, therefore concern over their adverse effects have resulted in extensive studies on their removal from contaminated soils. The main purpose of this study was to compare experimental results of PAHs removal, from a natural certified soil polluted with PAHs, by biological methods (using bioaugmentation and biostimulation in a solid-state culture) with those from supercritical fluid extraction (SFE), using supercritical ethane as solvent. The comparison of results between the two methods showed that maximal removal of naphthalene, acenaphthene, fluorene, and chrysene was performed using bioremediation; however, for the rest of the PAHs considered (fluoranthene, pyrene, and benz(a)anthracene) SFE resulted more efficient. Although bioremediation achieved higher removal ratios for certain hydrocarbons and takes advantage of the increased rate of natural biological processes, it takes longer time (i.e. 36 d vs. half an hour) than SFE and it is best for 2-3 PAHs rings. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of COD removal from pharmaceutical wastewater by electrocoagulation, photoelectrocoagulation, peroxi-electrocoagulation and peroxi-photoelectrocoagulation processes.

PubMed

Farhadi, Sajjad; Aminzadeh, Behnoush; Torabian, Ali; Khatibikamal, Vahid; Alizadeh Fard, Mohammad

2012-06-15

This work makes a comparison between electrocoagulation (EC), photoelectrocoagulation, peroxi-electrocoagulation and peroxi-photoelectrocoagulation processes to investigate the removal of chemical oxygen demand (COD) from pharmaceutical wastewater. The effects of operational parameters such as initial pH, current density, applied voltage, amount of hydrogen peroxide and electrolysis time on COD removal efficiency were investigated and the optimum operating range for each of these operating variables was experimentally determined. In electrocoagulation process, the optimum values of pH and voltage were determined to be 7 and 40 V, respectively. Desired pH and hydrogen peroxide concentration in the Fenton-based processes were found to be 3 and 300 mg/L, respectively. The amounts of COD, pH, electrical conductivity, temperature and total dissolved solids (TDS) were on-line monitored. Results indicated that under the optimum operating range for each process, the COD removal efficiency was in order of peroxi-electrocoagulation > peroxi-photoelectrocoagulation > photoelectrocoagulation>electrocoagulation. Finally, a kinetic study was carried out using the linear pseudo-second-order model and results showed that the pseudo-second-order equation provided the best correlation for the COD removal rate. Copyright © 2012 Elsevier B.V. All rights reserved.

Selective removals of heavy metals (Pb(2+), Cu(2+), and Cd(2+)) from wastewater by gelation with alginate for effective metal recovery.

PubMed

Wang, Fei; Lu, Xingwen; Li, Xiao-yan

2016-05-05

A novel method that uses the aqueous sodium alginate solution for direct gelation with metal ions is developed for effective removal and recovery of heavy metals from industrial wastewater. The experimental study was conducted on Pb(2+), Cu(2+), and Cd(2+) as the model heavy metals. The results show that gels can be formed rapidly between the metals and alginate in less than 10 min and the gelation rates fit well with the pseudo second-order kinetic model. The optimum dosing ratio of alginate to the metal ions was found to be between 2:1 and 3:1 for removing Pb(2+) and around 4:1 for removing Cu(2+) and Cd(2+) from wastewater, and the metal removal efficiency by gelation increased as the solution pH increased. Alginate exhibited a higher gelation affinity toward Pb(2+) than Cu(2+) and Cd(2+), which allowed a selective removal of Pb(2+) from the wastewater in the presence of Cu(2+) and Cd(2+) ions. Chemical analysis of the gels suggests that the gelation mainly occurred between the metal ions and the -COO(-) and -OH groups on alginate. By simple calcination of the metal-laden gels at 700 °C for 1 h, the heavy metals can be well recovered as valuable resources. The metals obtained after the thermal treatment are in the form of PbO, CuO, and CdO nanopowders with crystal sizes of around 150, 50, and 100 nm, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

The removal of the trivalent chromium from the leather tannery wastewater: the optimisation of the electro-coagulation process parameters.

PubMed

GilPavas, E; Dobrosz-Gómez, I; Gómez-García, M Á

2011-01-01

The capacity of the electro-coagulation (EC) process for the treatment of the wastewater containing Cr3+, resulting from a leather tannery industry placed in Medellin (Colombia), was evaluated. In order to assess the effect of some parameters, such as: the electrode type (Al and/or Fe), the distance between electrodes, the current density, the stirring velocity, and the initial Cr3+ concentration on its efficiency of removal (%RCr+3), a multifactorial experimental design was used. The %RCr3+ was defined as the response variable for the statistical analysis. In order to optimise the operational values for the chosen parameters, the response surface method (RSM) was applied. Additionally, the Biological Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), and the Total Organic Carbon (TOC) were monitored during the EC process. The electrodes made of aluminium appeared to be the most effective in the chromium removal from the wastewater under study. At pH equal to 4.52 and at 28°C, the optimal conditions of Cr3+ removal using the EC process were found, as follows: the initial Cr3+ concentration=3,596 mg/L, the electrode gap=0.5 cm, the stirring velocity=382.3 rpm, and the current density=57.87 mA/cm2. At those conditions, it was possible to reach 99.76% of Cr3+ removal, and 64% and 61% of mineralisation (TOC) and COD removal, respectively. A kinetic analysis was performed in order to verify the response capacity of the EC process at optimised parameter values.

Effectiveness of binaural beats in reducing preoperative dental anxiety.

PubMed

Isik, B K; Esen, A; Büyükerkmen, B; Kilinç, A; Menziletoglu, D

2017-07-01

Binaural beats are an auditory illusion perceived when two different pure-tone sine waves are presented one to each ear at a steady intensity and frequency. We evaluated their effectiveness in reducing preoperative anxiety in dentistry. Sixty patients (30 in each group) who were to have impacted third molars removed were studied (experimental group: 20 women and 10 men, mean (range) age 24 (18-35) years, and control group: 22 women and 8 men, mean (range) age 28 (15-47) years). All patients were fully informed about the operation preoperatively, and their anxiety recorded on a visual analogue scale (VAS). The local anaesthetic was given and the patients waited for 10minutes, during which those in the experimental group were asked to listen to binaural beats through stereo earphones (200Hz for the left ear and 209.3Hz for the right ear). No special treatment was given to the control group. In both groups anxiety was then recorded again, and the tooth removed in the usual way. The paired t test and t test were used to assess the significance of differences between groups. The degree of anxiety in the control group was unchanged after the second measurement (p=0.625), while that in the experimental group showed a significant reduction in anxiety (p=0.001). We conclude that binaural beats may be useful in reducing preoperative anxiety in dentistry. Copyright © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

EXPERIMENTAL STUDY OF HIGH LEVELS OF SO2 REMOVAL IN ATMOSPHERIC-PRESSURE FUIDIZED-BED COMBUSTORS

EPA Science Inventory

The report describes tests conducted in an atmospheric-pressure-fluidized-bed combustor (FBC) with a cross-section of 1 x 1.6 m) to demonstrate high levels of S02 removal when burning a high-sulfur coal and feeding limestone sorbent for S02 removal. The goal was to achieve 90-plu...

Cowbird removals unexpectedly increase productivity of a brood parasite and the songbird host.

PubMed

Kosciuch, Karl L; Sandercock, Brett K

2008-03-01

Generalist brood parasites reduce productivity and population growth of avian hosts and have been implicated in population declines of several songbirds of conservation concern. To estimate the demographic effects of brood parasitism on Bell's Vireos (Vireo bellii), we removed Brown-headed Cowbirds (Molothrus ater) in a replicated switchback experimental design. Cowbird removals decreased parasitism frequency from 77% and 85% at unmanipulated plots to 58% and 47% at removal plots in 2004 and 2005, respectively. Vireo productivity per pair was higher at cowbird removal plots when years were pooled (mean = 2.6 +/- 0.2 [SE] young per pair) compared to unmanipulated plots (1.2 +/- 0.1). Nest desertion frequency was lower at cowbird removal plots (35% of parasitized nests) compared to unmanipulated plots (69%) because removal of host eggs was the proximate cue for nest desertion, and vireos experienced lower rates of egg loss at cowbird removal plots. Nest success was higher among unparasitized than parasitized nests, and parasitized nests at cowbird removal plots had a higher probability of success than parasitized nests at unmanipulated plots. Unexpectedly, cowbird productivity from vireo pairs was higher at cowbird removal plots (mean = 0.3 +/- 0.06 young per pair) than at unmanipulated plots (0.1 +/- 0.03) because fewer parasitized nests were deserted and the probability of nest success was higher. Our study provides the first evidence that increases in cowbird productivity may be an unintended consequence of cowbird control programs, especially during the initial years of trapping when parasitism may only be moderately reduced. Thus, understanding the demographic impacts of cowbird removals requires an informed understanding of the behavioral ecology of host-parasite interactions.

Effect of thinning and soil treatments on Pinus ponderosa plantations: 15-year results

Treesearch

Jianwei Zhang; Jeff Webster; David H. Young; Gary O. Fiddler

2016-01-01

Thinning with removal of whole trees in a plantation or natural forest stand raises two main concerns – soil compaction from the ground-based machinery and nutrient depletion particularly with whole tree harvest as is often practiced for attendant fuels reduction. To address these concerns, two sets of experimental treatments were imposed in young ponderosa pine...

Protective effect of heat-treated cucumber (Cucumis sativus L.) juice on alcohol detoxification in experimental rats.

PubMed

Bajpai, Vivek K; Kim, Na-Hyung; Kim, Ji-Eun; Kim, Kangmin; Kang, Sun Chul

2016-05-01

In this study, heat-treated cucumber juice was assessed for its protective effect on blood alcohol levels and hepatic alcohol metabolic enzyme system in experimental rats. Initially, during detoxification of alcohol, all groups were orally dosed to 22% alcohol (6ml/kg body weight) along with different concentrations of heat-treated cucumber juice (10, 100 and 500mg/kg) and commercial goods for hangover-removal on sale (2ml/kg). Cucumber juice was dosed before 30 min, and simultaneously after 30min of alcohol administration, and its hepatoprotective effect on blood alcohol levels and hepatic alcohol metabolic enzyme system in experimental rats was evaluated. As a result, after 7h, remarkable reduction was found in the blood alcohol levels for all concentrations of cucumber juice treatment. Treatment with cucumber juice resulted in increasing dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) enzymatic activities in rat liver at 9h after alcohol administration thereby stimulated blood alcohol metabolism as compared with control group. The effect of heat-treated cucumber juice on alcohol detoxification was observed only in the rats treated before 30min from alcohol administration. These findings indicate that heat-treated cucumber juice has significant protective effect on alcohol detoxification in experimental rats, suggesting its usefulness in the treatment of liver injury caused by alcohol consumption.

-A practical application of reduced-copper antifouling paint in marine biological research.

PubMed

Jerabek, Andrea S; Wall, Kara R; Stallings, Christopher D

2016-01-01

Biofouling of experimental cages and other field apparatuses can be problematic for scientists and has traditionally been addressed using frequent manual removal (e.g., scraping, scrubbing). Recent environmental restrictions and legislative changes have driven the development of less hazardous antifouling products, making antifouling paint a potential alternative option to manual removal. Consequently, the viability of using these newly developed products as a replacement for the manual cleaning of exclusion cages was experimentally investigated. There were six treatments tested, comprising three with settlement tiles in experimental cages coated with antifouling paint, two with settlement tiles in unpainted experimental cages, and one cage-free suspended tile. The three antifouling treatments comprised two reduced-copper paints (21% Cu2O and 40% Cu2O) and one copper-free, Econea (™)-based paint (labeled "ecofriendly"). Antifouling paints were assessed for performance of preventing fouling of the cages and whether they elicited local effects on settlement tiles contained within them. All three paints performed well to reduce fouling of the cages during the initial six weeks of the experiment, but the efficacy of "ecofriendly" paint began to decrease during an extended deployment that lasted 14 weeks. The macro-community composition, biomass, and percent cover of settled organism on tiles within cages treated with copper-based paints (21% and 40% concentrations) were indistinguishable from tiles within the manually scrubbed cages. In contrast, settlement to tiles from the "ecofriendly" treatment was different in composition of macro-community and lower in biomass, suggesting the presence of local effects and therefore rendering it unsuitable for use in settlement experiments. The results of this study suggest that reduced-copper paints have the potential to serve as an alternative to manual maintenance, which may be useful for deployments in locations that are difficult to access on a frequent schedule.

Effectiveness of Sonic, Ultrasonic, and Photon-Induced Photoacoustic Streaming Activation of NaOCl on Filling Material Removal Following Retreatment in Oval Canal Anatomy.

PubMed

Jiang, Shan; Zou, Ting; Li, Dongxia; Chang, Jeffery W W; Huang, Xiaojing; Zhang, Chengfei

2016-01-01

This study aimed to assess the effectiveness of sonic, ultrasonic and laser [photon-induced photoacoustic streaming (PIPS)] irrigation activation in removing filling remnants from oval root canals after standard canal retreatment procedures with the ProTaper universal rotary retreatment system. Twenty-eight maxillary first premolars were instrumented with ProTaper NiTi rotary instruments and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. After storage at 37°C and 100% humidity for 1 week, the specimens were retreated with the ProTaper universal retreatment system for the removal of filling material. Teeth were then randomly assigned into four groups (n = 7): group 1, positive control; group 2, retreated with sonic irrigation; group 3, retreated with ultrasonic irrigation; and group 4, retreated with laser irradiation. The specimens were scanned using micro-CT before instrumentation, after obturation and mechanical retreatment, and after additional activation procedures. The percentage volume of the filling remnants was measured. Specimens were split longitudinally after micro-CT scan, canal walls were examined using scanning electron microscopy (SEM), and the amount of residual filling material was scored. The filling materials' removal efficacy in the three experimental groups was higher than that of the control group (p < 0.05), whereas filling materials ranging from 1.46 ± 0.30 to 2.21 ± 0.46 mm(3) remained in the canal in all three experimental groups. Additionally, there was a significantly greater reduction in the amount of filling remnants in the PIPS group than in the sonic and ultrasonic groups (both p < 0.05), and significantly greater reduction in the ultrasonic group than the sonic group (p < 0.05). Activation of NaOCl with PIPS showed significantly better performance than sonic and ultrasonic techniques in removing the filling remnants following mechanical retreatment of oval root canals. The ultrasonic technique also performed better than the sonic technique. However, none of the additional activation procedures was able to completely eliminate the filling remnants.

Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.

PubMed

Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

2008-01-01

Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application.

Total morphine stability in urine specimens stored under various conditions.

PubMed

Chang, B L; Huang, M K; Tsai, Y Y

2000-09-01

The stability of total morphine in urine stored under various conditions was studied using control and experimental specimens. Samples in the control group were prepared using drug-free urine spiked with morphine at three concentration levels (300, 1000, and 2500 ng/mL), each with the pH adjusted to 5.5, 6.5, and 7.5. Samples in the experimental group came from 20 alleged heroin addicts (provided by Taipei Municipal Psychiatric Hospital). Samples in both groups were divided into two categories--one with and one without the precipitate (formed at 0 degrees C) removed. Samples in each of these two categories were further divided into two sub-groups--one with and one without sodium azide (0.05%) added. Total morphine contents in these samples were first determined by gas chromatography-mass spectrometry prior to storage and at 6, 12, 18, and 24 months following storage at -20, 4, 25, and 35 degrees C. Effects of sample treatment (azide addition and precipitate removal), pH, and storage temperature and length were evaluated by examining the percentage of total morphine remaining at the four time intervals following the initial determination. Major findings were as follows: (1) total morphine decomposition was minimal when stored for 12 months at -20 degrees C, which is a common current practice; (2) samples with lower initial sample pH had slower total morphine decomposition rates; and (3) azide addition appeared to have no detectable effect, whereas precipitate removal appeared to marginally reduce the decomposition rate, especially for samples with lower pH.

An improved pyrite pretreatment protocol for kinetic and isotopic studies

NASA Astrophysics Data System (ADS)

Mirzoyan, Natella; Kamyshny, Alexey; Halevy, Itay

2014-05-01

An improved pyrite pretreatment protocol for kinetic and isotopic studies Natella Mirzoyan1, Alexey Kamyshny Jr.2, Itay Halevy1 1Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel 2Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel Pyrite is one of the most abundant and widespread of the sulfide minerals with a central role in biogeochemical cycles of iron and sulfur. Due to its diverse roles in the natural and anthropogenic sulfur cycle, pyrite has been extensively studied in various experimental investigations of the kinetics of its dissolution and oxidation, the isotopic fractionations associated with these reactions, and the microbiological processes involved. Pretreatment of pyrite for removal of oxidation impurities to prevent experimental artifacts and inaccuracies is often practiced. While numerous pyrite-cleaning methods have been used in experiments, a common pyrite pretreatment method, often used to investigate pyrite chemistry by the isotopic fractionations associated with it, includes several rinses by HCl, acetone and deionized water. Elemental sulfur (S0) is a common product of incomplete pyrite oxidation. Removal of S0 is desirable to avoid experimental biases associated with its participation in pyrite transformations, but is more complicated than the removal of sulfate. Although rinsing with an organic solvent is in part aimed at removing S0, to the best of our knowledge, the extraction efficiency of S0 in existing protocols has not been assessed. We have developed and tested a new protocol for elemental sulfur removal from the surface of pyrite by ultrasonication with warm acetone. Our data demonstrate the presence of large fractions of S0 on untreated pyrite particle surfaces, of which only approximately 60% was removed by the commonly used pretreatment method. The new protocol described here was found to be more efficient at S0 removal than the commonly used method, and was capable of removing virtually all S0 from the pyrite grains. As pyrite oxidation and dissolution processes are surface-dependent, and even the slightest coating by Fe2+ or sulfide oxidation products can sharply decrease pyrite reactivity, the improved removal of S0 prevents such decreases and allows clearer insights into pyrite reaction mechanisms to be gained from experimental studies. In addition to S0 removal, the suggested method was shown not to introduce any biases in the particle size distribution. The main difference observed between the two protocols is the removal of larger amounts of surface-attached fine particles in the proposed method along with S0. This also removes a potential bias, associated with the surface area of pyrite available for chemical reaction. The suggested pyrite pretreatment protocol is more efficient in removal of S0 contamination from pyrite grains and provides multiple advantages for both kinetic and isotopic investigations of pyrite transformations under various environmental conditions.

Use of fugacity model to analyze temperature-dependent removal of micro-contaminants in sewage treatment plants.

PubMed

Thompson, Kelly; Zhang, Jianying; Zhang, Chunlong

2011-08-01

Effluents from sewage treatment plants (STPs) are known to contain residual micro-contaminants including endocrine disrupting chemicals (EDCs) despite the utilization of various removal processes. Temperature alters the efficacy of removal processes; however, experimental measurements of EDC removal at various temperatures are limited. Extrapolation of EDC behavior over a wide temperature range is possible using available physicochemical property data followed by the correction of temperature dependency. A level II fugacity-based STP model was employed by inputting parameters obtained from the literature and estimated by the US EPA's Estimations Programs Interface (EPI) including EPI's BIOWIN for temperature-dependent biodegradation half-lives. EDC removals in a three-stage activated sludge system were modeled under various temperatures and hydraulic retention times (HRTs) for representative compounds of various properties. Sensitivity analysis indicates that temperature plays a significant role in the model outcomes. Increasing temperature considerably enhances the removal of β-estradiol, ethinyestradiol, bisphenol, phenol, and tetrachloroethylene, but not testosterone with the highest biodegradation rate. The shortcomings of BIOWIN were mitigated by the correction of highly temperature-dependent biodegradation rates using the Arrhenius equation. The model predicts well the effects of operating temperature and HRTs on the removal via volatilization, adsorption, and biodegradation. The model also reveals that an impractically long HRT is needed to achieve a high EDC removal. The STP model along with temperature corrections is able to provide some useful insight into the different patterns of STP performance, and useful operational considerations relevant to EDC removal at winter low temperatures. Copyright © 2011 Elsevier Ltd. All rights reserved.

Adaptive color demosaicing and false color removal

NASA Astrophysics Data System (ADS)

Guarnera, Mirko; Messina, Giuseppe; Tomaselli, Valeria

2010-04-01

Color interpolation solutions drastically influence the quality of the whole image generation pipeline, so they must guarantee the rendering of high quality pictures by avoiding typical artifacts such as blurring, zipper effects, and false colors. Moreover, demosaicing should avoid emphasizing typical artifacts of real sensors data, such as noise and green imbalance effect, which would be further accentuated by the subsequent steps of the processing pipeline. We propose a new adaptive algorithm that decides the interpolation technique to apply to each pixel, according to its neighborhood analysis. Edges are effectively interpolated through a directional filtering approach that interpolates the missing colors, selecting the suitable filter depending on edge orientation. Regions close to edges are interpolated through a simpler demosaicing approach. Thus flat regions are identified and low-pass filtered to eliminate some residual noise and to minimize the annoying green imbalance effect. Finally, an effective false color removal algorithm is used as a postprocessing step to eliminate residual color errors. The experimental results show how sharp edges are preserved, whereas undesired zipper effects are reduced, improving the edge resolution itself and obtaining superior image quality.

Simultaneously removal of inorganic arsenic species from stored rainwater in arsenic endemic area by leaves of Tecomella undulata: a multivariate study.

PubMed

Brahman, Kapil Dev; Kazi, Tasneem Gul; Afridi, Hassan Imran; Baig, Jameel Ahmed; Abro, Muhammad Ishaque; Arain, Sadaf Sadia; Ali, Jamshed; Khan, Sumaira

2016-08-01

In the present study, an indigenous biosorbent (leaves of Tecomella undulata) was used for the simultaneous removal of inorganic arsenic species (As(III) and As(V)) from the stored rainwater in Tharparkar, Pakistan. The Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of six factors/variables on the biosorption of inorganic arsenic species, simultaneously. Central composite design (CCD) was used to found the optimum values of significant factors for the removal of As(III) and As(V). Initial concentrations of both inorganic As species, pH, biosorbent dose, and contact time were selected as independent factors in CCD, while the adsorption capacity (q e) was considered as a response function. The separation of inorganic As species in water samples before and after biosorption was carried out by cloud point and solid-phase extraction methods. Theoretical values of pH, concentration of analytes, biosorbent dose, and contact time were calculated by quadratic equation for 100 % biosorption of both inorganic As species in aqueous media. Experimental data were modeled by Langmuir and Freundlich isotherms. Thermodynamic and kinetic study indicated that the biosorption of As(III) and As(V) was followed by pseudo second order. It was concluded that the indigenous biosorbent material efficiently and simultaneously removed both As species in the range of 70.8 to 98.5 % of total contents in studied ground water samples. Graphical abstract Optimizing the significant varable by central 2(3) + star orthogonal composite design.

Retaining biodiversity in intensive farmland: epiphyte removal in oil palm plantations does not affect yield.

PubMed

Prescott, Graham W; Edwards, David P; Foster, William A

2015-05-01

The expansion of agriculture into tropical forest frontiers is one of the primary drivers of the global extinction crisis, resulting in calls to intensify tropical agriculture to reduce demand for more forest land and thus spare land for nature. Intensification is likely to reduce habitat complexity, with profound consequences for biodiversity within agricultural landscapes. Understanding which features of habitat complexity are essential for maintaining biodiversity and associated ecosystem services within agricultural landscapes without compromising productivity is therefore key to limiting the environmental damage associated with producing food intensively. Here, we focus on oil palm, a rapidly expanding crop in the tropics and subject to frequent calls for increased intensification. One promoted strategy is to remove epiphytes that cover the trunks of oil palms, and we ask whether this treatment affects either biodiversity or yield. We experimentally tested this by removing epiphytes from four-hectare plots and seeing if the biodiversity and production of fruit bunches 2 months and 16 months later differed from equivalent control plots where epiphytes were left uncut. We found a species-rich and taxonomically diverse epiphyte community of 58 species from 31 families. Epiphyte removal did not affect the production of fresh fruit bunches, or the species richness and community composition of birds and ants, although the impact on other components of biodiversity remains unknown. We conclude that as they do not adversely affect palm oil production, the diverse epiphyte flora should be left uncut. Our results underscore the importance of experimentally determining the effects of habitat complexity on yield before introducing intensive methods with no discernible benefits.

Equilibrium and kinetics of adsorption of phosphate onto iron-doped activated carbon.

PubMed

Wang, Zhengfang; Nie, Er; Li, Jihua; Yang, Mo; Zhao, Yongjun; Luo, Xingzhang; Zheng, Zheng

2011-08-01

Two series of activated carbons modified by Fe (II) and Fe (III) (denoted as AC/N-Fe(II) and AC/N-Fe(III)), respectively, were used as adsorbents for the removal of phosphate in aqueous solutions. The synthesized adsorbent materials were investigated by different experimental analysis means. The adsorption of phosphate on activated carbons has been studied in kinetic and equilibrium conditions taking into account the adsorbate concentration, temperature, and solution pH as major influential factors. Maximum removals of phosphate are obtained in the pH range of 3.78-6.84 for both adsorbents. Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Kinetic studies revealed that the adsorption process followed a pseudo-second order kinetic model. Results suggest that the main phase formed in AC/N-Fe(II) and AC/N-Fe(III) is goethite and akaganeite, respectively; the presence of iron oxides significantly affected the surface area and the pore structure of the activated carbon. Studies revealed that iron-doped activated carbons were effective in removing phosphate. AC/N-Fe(II) has a higher phosphate removal capacity than AC/N-Fe(III), which could be attributed to its better intra-particle diffusion and higher binding energy. The activation energy for adsorption was calculated to be 22.23 and 10.89 kJ mol(-1) for AC/N-Fe(II) and AC/N-Fe(III), respectively. The adsorption process was complex; both surface adsorption and intra-particle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.

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

PubMed

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

2018-03-01

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

Optimal design and dynamic impact tests of removable bollards

NASA Astrophysics Data System (ADS)

Chen, Suwen; Liu, Tianyi; Li, Guoqiang; Liu, Qing; Sun, Jianyun

2017-10-01

Anti-ram bollard systems, which are installed around buildings and infrastructure, can prevent unauthorized vehicles from entering, maintain distance from vehicle-borne improvised explosive devices (VBIED) and reduce the corresponding damage. Compared with a fixed bollard system, a removable bollard system provides more flexibility as it can be removed when needed. This paper first proposes a new type of K4-rated removable anti-ram bollard system. To simulate the collision of a vehicle hitting the bollard system, a finite element model was then built and verified through comparison of numerical simulation results and existing experimental results. Based on the orthogonal design method, the factors influencing the safety and economy of this proposed system were examined and sorted according to their importance. An optimal design scheme was then produced. Finally, to validate the effectiveness of the proposed design scheme, four dynamic impact tests, including two front impact tests and two side impact tests, have been conducted according to BSI Specifications. The residual rotation angles of the specimen are smaller than 30º and satisfy the requirements of the BSI Specification.

Removal of Organophosphorus Pesticides from Aqueous Solution by Magnetic Fe3O4/Red Mud-Nanoparticles.

PubMed

Aydin, Senar

2016-12-01

  The aim of this study was to investigate the usability of magnetic Fe3O4/red mud nanoparticles (NPs) for the removal of organophosphorus pesticides from water samples. The effect of various experimental parameters such as red mud amount in Fe3O4/red mud-NPs, pH, contact time, initial pesticide concentrations and adsorbent dose was studied in order to find the optimum conditions for their removal in a batch process. The Fe3O4/red mud-NPs were characterized by using TGA, SEM, XRD, VSM, and determination of the BET surface area. After the regenerated Fe3O4/red mud-NPs were used three times, the sorption capacity and the magnetic separability were observed to be unaffected. Freundlich model described the sorption process better than Langmuir isotherm and the pseudo second-order kinetic model was determined as the best-fit model. The film diffusion mechanism was found to be a main rate control mechanism. The Fe3O4/red mud-NPs satisfactorily removed the OPPS from real water samples.

PAMAM dendrimers and graphene: Materials for removing aromatic contaminants from water

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

DeFever, Ryan S.; Geitner, Nicholas K.; Bhattacharya, Priyanka

2015-04-07

We present results from experiments and atomistic molecular dynamics simulations on the association of naphthalene with polyamidoamine (PAMAM) dendrimers and graphene oxide (GrO). Specifically, we investigate 3rd-6th generation (G3-G6) PAMAM dendrimers and GrO with different levels of oxidation. The work is motivated by the potential applications of these materials in removing polycyclic aromatic hydrocarbon contaminants from water. Our experimental results indicate that graphene oxide outperforms dendrimers in removing naphthalene from water. Molecular dynamics simulations suggest that the prominent factors driving naphthalene association to these seemingly disparate materials are similar. Interestingly, we find that cooperative interactions between the naphthalene molecules playmore » a significant role in enhancing their association to the dendrimers and graphene oxide. Our findings highlight that while selection of appropriate materials is important, the interactions between the contaminants themselves can also be important in governing the effectiveness of a given material. The combined use of experiments and molecular dynamics simulations allows us to comment on the possible factors resulting in better performance of graphene oxide in removing naphthalene from water.« less

Adherent Raindrop Modeling, Detectionand Removal in Video.

PubMed

You, Shaodi; Tan, Robby T; Kawakami, Rei; Mukaigawa, Yasuhiro; Ikeuchi, Katsushi

2016-09-01

Raindrops adhered to a windscreen or window glass can significantly degrade the visibility of a scene. Modeling, detecting and removing raindrops will, therefore, benefit many computer vision applications, particularly outdoor surveillance systems and intelligent vehicle systems. In this paper, a method that automatically detects and removes adherent raindrops is introduced. The core idea is to exploit the local spatio-temporal derivatives of raindrops. To accomplish the idea, we first model adherent raindrops using law of physics, and detect raindrops based on these models in combination with motion and intensity temporal derivatives of the input video. Having detected the raindrops, we remove them and restore the images based on an analysis that some areas of raindrops completely occludes the scene, and some other areas occlude only partially. For partially occluding areas, we restore them by retrieving as much as possible information of the scene, namely, by solving a blending function on the detected partially occluding areas using the temporal intensity derivative. For completely occluding areas, we recover them by using a video completion technique. Experimental results using various real videos show the effectiveness of our method.

Influence of ɣ and ultrasonic irradiations on the physicochemical properties of CeO2-Fe2O3-Al2O3 for textile dyes removal applications

NASA Astrophysics Data System (ADS)

Ibrahim, Marwa M.; El-Molla, Sahar A.; Ismail, Sahar A.

2018-04-01

In this study highly effective adsorbent ternary mixed oxide CeO2-Fe2O3-Al2O3 was prepared by precipitation method. Various methods used to treat the mixed hydroxide like calcination, ultrasonic, hydrothermal and ɣ radiation with different doses to obtain the ternary mixed oxide. XRD, TEM, EDX, FTIR and SBET are used to study the physicochemical properties of nanoparticles. The CFAH and CFAɣ0.8 have the different morphologies and high surface area. Batch adsorption experiments were performed to remove anionic Remazol Red RB-133 dye. The experimental data showed that The CFAH and CFAɣ0.8 have high adsorption rate for removing of dye. The removal of dye is enhanced by ultrasonic radiation and high temperature. The adsorption process was fitted well for pseudo second order kinetics and followed the Freundlich isotherm model. In addition to, Thermodynamic results of adsorption process displayed that, the adsorption of dye on adsorbent was spontaneous, endothermic and chemisorptions process.

Optimized Production of Coal Fly Ash Derived Synthetic Zeolites for Mercury Removal from Wastewater

NASA Astrophysics Data System (ADS)

Tauanov, Z.; Shah, D.; Itskos, G.; Inglezakis, V.

2017-09-01

Coal fly ash (CFA) derived synthetic zeolites have become popular with recent advances and its ever-expanding range of applications, particularly as an adsorbent for water and gas purification and as a binder or additive in the construction industry and agriculture. Among these applications, perpetual interest has been in utilization of CFA derived synthetic zeolites for removal of heavy metals from wastewater. We herein focus on utilization of locally available CFA for efficient adsorption of mercury from wastewater. To this end, experimental conditions were investigated so that to produce synthetic zeolites from Kazakhstani CFAs with conversion into zeolite up to 78%, which has remarkably high magnetite content. In particular, the effect of synthesis reaction temperature, reaction time, and loading of adsorbent were systematically investigated and optimized. All produced synthetic zeolites and the respective CFAs were characterized using XRD, XRF, PSA and porosimetric instruments to obtain microstructural and mineralogical data. Furthermore, the synthesized zeolites were studied for the removal of mercury from aqueous solutions. A comparison of removal eficiency and its relationship to the physical and chemical properties of the synthetic zeolites were analyzed and interpreted.

Treatment of winery wastewater in a conventional municipal activated sludge process: five years of experience.

PubMed

Bolzonella, D; Zanette, M; Battistoni, P; Cecchi, F

2007-01-01

A full-scale wastewater treatment plant where municipal and winery wastewaters were co-treated was studied for five years. The experimental results showed that suspended solids, COD, nitrogen and phosphorous were effectively removed both during the treatment of municipal wastewater and the cotreatment of municipal and winery wastewater. The sludge production increase from 4 tons to 5.5 tons per day during the harvesting and wine making period. In any case the specific sludge production was 0.2 kgMLVSS per kgCOD(removed) despite the organic loading increasing. About 70% of the COD was removed through respiration. Also the energy demand increased from 6,000 to 7,000 kWh per day. The estimated costs for the treatment of the winery wastewater was 0.2-0.3 Euros per m3 of treated wastewater. With reference to the process efficiency, the nitrogen removal was just 20%. The co-treatment of municipal and winery wastewater in conventional activated sludge processes can be a feasible solution for the treatment of these streams at relatively low costs.

Effects of anionic surfactant on n-hexane removal in biofilters.

PubMed

Cheng, Yan; He, Huijun; Yang, Chunping; Yan, Zhou; Zeng, Guangming; Qian, Hui

2016-05-01

The biodegradability of three anion surfactants by biofilm microorganisms and the toxicity of the most readily biodegradable surfactant to biofilm microorganisms were examined using batch experiments, and the optimal concentration of SDS for enhanced removal of hexane was investigated using two biotrickling filters (BTFs) for comparison. Results showed that SDS could be biodegraded by microorganisms, and its toxicity to microorganisms within the experimental range was negligible. The best concentration of SDS in biofiltration of n-hexane was 0.1 CMC and the elimination capacity (EC) of 50.4 g m(-3) h(-1) was achieved at a fixed loading rate (LR) of 72 g m(-3) h(-1). When an inlet concentration of n-hexane increased from 600 to 850 mg m(-3), the removal efficiency (RE) decreased from 67% to 41% by BTF2 (with SDS) and from 52% to 42% by BTF1 (without SDS). SDS could enhance hexane removal from 43% (BTF1) to 60% (BTF2) at gas empty-bed residence time (EBRT) of 7.5 s and an inlet concentration of 200 mg m(-3). Copyright © 2016. Published by Elsevier Ltd.

PAMAM dendrimers and graphene: materials for removing aromatic contaminants from water.

PubMed

DeFever, Ryan S; Geitner, Nicholas K; Bhattacharya, Priyanka; Ding, Feng; Ke, Pu Chun; Sarupria, Sapna

2015-04-07

We present results from experiments and atomistic molecular dynamics simulations on the remediation of naphthalene by polyamidoamine (PAMAM) dendrimers and graphene oxide (GrO). Specifically, we investigate 3rd-6th generation (G3-G6) PAMAM dendrimers and GrO with different levels of oxidation. The work is motivated by the potential applications of these emerging nanomaterials in removing polycyclic aromatic hydrocarbon contaminants from water. Our experimental results indicate that GrO outperforms dendrimers in removing naphthalene from water. Molecular dynamics simulations suggest that the prominent factors driving naphthalene association to these seemingly disparate materials are similar. Interestingly, we find that cooperative interactions between the naphthalene molecules play a significant role in enhancing their association to the dendrimers and GrO. Our findings highlight that while selection of appropriate materials is important, the interactions between the contaminants themselves can also be important in governing the effectiveness of a given material. The combined use of experiments and molecular dynamics simulations allows us to comment on the possible factors resulting in better performance of GrO in removing polyaromatic contaminants from water.

Removal Enhancement of Basic Blue 41 BY RGO-TiO2 Nanocomposite Synthesized Using Pulsed Laser

NASA Astrophysics Data System (ADS)

Ghasemi, Fatemeh; Kimiagar, Salimeh; Shahbazi, Mozhgan; Vojoudi, Hossein

Graphene oxide (GO) and GO-TiO2 nanocomposite was produced then reduced under pulse laser irradiation (RGO-TiO2). Basic blue 41 (bb41) dye was removed from aqueous solutions by using RGO-TiO2 nanocomposites. The UV-Vis absorption and FTIR analysis were utilized to confirm the reduction of GO-TiO2 to RGO-TiO2. The results showed complete reduction of GO. X-ray diffraction (XRD), Raman spectra and scanning electron microscopy (SEM) analysis were applied to approve the RGO-TiO2 nanocomposite structure. The effect of pH on the bb41 removal by RGO-TiO2 was studied varying the pH from 1 to 11. The optimum pH and adsorbent dosage were found to be 9 and 0.2g/L with 98% efficiency, respectively. The calculated coefficients demonstrated that the Langmuir model was fixed to the experimental data. The results indicated that RGO-TiO2 could be engaged as an exceptional sorbent to remove bb41 dye which is in aqueous solution.

Investigation and optimization of the novel UASB-MFC integrated system for sulfate removal and bioelectricity generation using the response surface methodology (RSM).

PubMed

Zhang, Baogang; Zhang, Jing; Yang, Qi; Feng, Chuanping; Zhu, Yuling; Ye, Zhengfang; Ni, Jinren

2012-11-01

COD/sulfate ratio and hydraulic residence time (HRT), both of which influence sulfate loadings jointly, are recognized as the most two important affecting factors for sulfate removal and bioelectricity generation in the novel up-flow anaerobic sludge blanket reactor-microbial fuel cell (UASB-MFC) integrated system. The response surface methodology (RSM) was employed for the optimization of this system and the optimum condition with COD/sulfate ratio of 2.3 and HRT of 54.3h was obtained with the target of maximizing the power output. In terms of maximizing the total sulfate removal efficiency, the obtained optimum condition was COD/sulfate ratio of 3.7 and HRT of 55.6h. Experimental results indicated the undistorted simulation and reliable optimized results. These demonstrated that RSM was effective to evaluate and optimize the UASB-MFC system for sulfate removal and energy recovery, providing a promising guide to further improvement of the system for potential applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

The removal of COD and NH3-N from atrazine production wastewater treatment using UV/O3: experimental investigation and kinetic modeling.

PubMed

Jing, Liang; Chen, Bing; Wen, Diya; Zheng, Jisi; Zhang, Baiyu

2018-01-01

In this study, a UV/O 3 hybrid advanced oxidation system was used to remove chemical oxygen demand (COD), ammonia nitrogen (NH 3 -N), and atrazine (ATZ) from ATZ production wastewater. The removal of COD and NH 3 -N, under different UV and O 3 conditions, was found to follow pseudo-first-order kinetics with rate constants ranging from 0.0001-0.0048 and 0.0015-0.0056 min -1 , respectively. The removal efficiency of ATZ was over 95% after 180 min treatment, regardless the level of UV power. A kinetic model was further proposed to simulate the removal processes and to quantify the individual roles and contributions of photolysis, direct O 3 oxidation, and hydroxyl radical (OH·) induced oxidation. The experimental and kinetic modeling results agreed reasonably well with deviations of 12.2 and 13.1% for the removal of COD and NH 3 -N, respectively. Photolysis contributed appreciably to the degradation of ATZ, while OH· played a dominant role for the removal of both COD and NH 3 -N, especially in alkaline environments. This study provides insights into the treatment of ATZ containing wastewater using UV/O 3 and broadens the knowledge of kinetics of ozone-based advanced oxidation processes.

Response surface methodology investigation into the interactions between arsenic and humic acid in water during the coagulation process.

PubMed

Watson, Malcolm Alexander; Tubić, Aleksandra; Agbaba, Jasmina; Nikić, Jasmina; Maletić, Snežana; Molnar Jazić, Jelena; Dalmacija, Božo

2016-07-15

Interactions between arsenic and natural organic matter (NOM) are key limiting factors during the optimisation of drinking water treatment when significant amounts of both must be removed. This work uses Response Surface Methodology (RSM) to investigate how they interact during their simultaneous removal by iron chloride coagulation, using humic acid (HA) as a model NOM substance. Using a three factor Box-Behnken experimental design, As and HA removals were modelled, as well as a combined removal response. ANOVA results showed the significance of the coagulant dose for all three responses. At high initial arsenic concentrations (200μg/l), As removal was significantly hindered by the presence of HA. In contrast, the HA removal response was found to be largely independent of the initial As concentration, with the optimum coagulant dose increasing at increasing HA concentrations. The combined response was similar to the HA removal response, and the interactions evident are most interesting in terms of optimising treatment processes during the preparation of drinking water, highlighting the importance of utilizing RSM for such investigations. The combined response model was successfully validated with two different groundwaters used for drinking water supply in the Republic of Serbia, showing excellent agreement under similar experimental conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Adolescents' perceptions of cigarette brand image: does plain packaging make a difference?

PubMed

Germain, Daniella; Wakefield, Melanie A; Durkin, Sarah J

2010-04-01

To examine the effect of plain packaging on adolescents' perceptions of cigarette packs, attributes of smokers, and expectations of cigarette taste, and to identify the effect of increasing the size of pictorial health warnings on appraisal of plain packs. We used a 5 (degree of plain packaging and graphic health warning)x 3 (brand type) between-subjects experimental design, using a Web-based methodology to expose adolescents to one randomly selected cigarette pack, during which respondents completed ratings. When brand elements such as color, branded fonts, and imagery were progressively removed from cigarette packs, adolescents perceived packs to be less appealing, rated attributes of a typical smoker of the pack less positively, and had more negative expectations of cigarette taste. Pack appeal was reduced even further when the size of the pictorial health warning on the most plain pack was increased from 30% to 80% of the pack face, with this effect apparent among susceptible nonsmokers, experimenters, and established smokers. Removing as much brand information from cigarette packs as possible is likely to reduce positive cigarette brand image associations among adolescents. By additionally increasing the size of pictorial health warnings, positive pack perceptions of those who are at greater risk of becoming regular addicted adult smokers are most likely to be reduced. Copyright 2010 Society for Adolescent Medicine. Published by Elsevier Inc. All rights reserved.

Evaluation of water matrix effects, experimental parameters, and the degradation pathway during the TiO2 photocatalytical treatment of the antibiotic dicloxacillin.

PubMed

Villegas-Guzman, Paola; Silva-Agredo, Javier; González-Gómez, Duván; Giraldo-Aguirre, Ana L; Flórez-Acosta, Oscar; Torres-Palma, Ricardo A

2015-01-01

The photocalytic degradation of dicloxacillin (DXC) using TiO2 was studied in synthetic and natural waters. The degradation route and the effect of different experimental variables such as pH, applied power, and the initial concentrations of DXC and the catalyst were investigated. The best performances were achieved at a natural pH 5.8 and using 2.0 g L(-1) of TiO2 with 150 W of applied power. The photodegradation process followed Langmuir-Hinshelwood kinetics. The water matrix effect was evaluated in terms of degradation efficiency in the presence of organic compounds (oxalic acid, glucose), Fe(2+) ion and natural water. An increase in degradation was observed when ferrous ion was part of the solution, but the process was inhibited with all evaluated organic compounds. Similarly, inhibition was observed when natural water was used instead of distilled water. The extent of degradation of the process was evaluated following the evolution of chemical oxygen demand (COD), antimicrobial activity (AA), total organic carbon (TOC) and biochemical oxygen demand (BOD5). Total removal of DXC was achieved after 120 min of treatment and 95% mineralization was observed after 480 min of treatment. Additionally, the total removal of antimicrobial activity and a high level of biodegradability were observed after the photocalytical system had been operating for 240 min.

Modeling of an integrated fermentation/membrane extraction process for the production of 2-phenylethanol and 2-phenylethylacetate.

PubMed

Adler, Philipp; Hugen, Thorsten; Wiewiora, Marzena; Kunz, Benno

2011-03-07

An unstructured model for an integrated fermentation/membrane extraction process for the production of the aroma compounds 2-phenylethanol and 2-phenylethylacetate by Kluyveromyces marxianus CBS 600 was developed. The extent to which this model, based only on data from the conventional fermentation and separation processes, provided an estimation of the integrated process was evaluated. The effect of product inhibition on specific growth rate and on biomass yield by both aroma compounds was approximated by multivariate regression. Simulations of the respective submodels for fermentation and the separation process matched well with experimental results. With respect to the in situ product removal (ISPR) process, the effect of reduced product inhibition due to product removal on specific growth rate and biomass yield was predicted adequately by the model simulations. Overall product yields were increased considerably in this process (4.0 g/L 2-PE+2-PEA vs. 1.4 g/L in conventional fermentation) and were even higher than predicted by the model. To describe the effect of product concentration on product formation itself, the model was extended using results from the conventional and the ISPR process, thus agreement between model and experimental data improved notably. Therefore, this model can be a useful tool for the development and optimization of an efficient integrated bioprocess. Copyright © 2010 Elsevier Inc. All rights reserved.

Long-term effects of drinking-water treatment residuals on dissolved phosphorus export from vegetated buffer strips.

PubMed

Habibiandehkordi, Reza; Quinton, John N; Surridge, Ben W J

2015-04-01

The export of dissolved phosphorus (P) in surface runoff from agricultural land can lead to water quality degradation. Surface application of aluminium (Al)-based water treatment residuals (Al-WTRs) to vegetated buffer strip (VBS) soils can enhance P removal from surface runoff during single runoff events. However, the longer-term effects on P removal in VBSs following application of products such as Al-WTR remain uncertain. We used field experimental plots to examine the long-term effects of applying a freshly generated Al-WTR to VBSs on dissolved P export during multiple runoff events, occurring between 1 day and 42 weeks after the application of Al-WTR. Vegetated buffer strip plots amended with Al-WTR significantly reduced soluble reactive P and total dissolved P concentrations in surface runoff compared to both unamended VBS plots and control plots. However, the effectiveness of Al-WTR decreased over time, by approximately 70% after 42 weeks compared to a day following Al-WTR application. Reduced performance did not appear to be due to drying of Al-WTR in the field. Instead, the development of preferential flow paths as well as burying of Al-WTR with freshly deposited sediments may explain these observations. Better understanding of the processes controlling long-term P removal by Al-WTR is required for effective management of VBSs.

Effects of three kinds of organic acids on phosphorus recovery by magnesium ammonium phosphate (MAP) crystallization from synthetic swine wastewater.

PubMed

Song, Yonghui; Dai, Yunrong; Hu, Qiong; Yu, Xiaohua; Qian, Feng

2014-04-01

P recovery from swine wastewater has become a great concern as a result of the high demand for P resources and its potential eutrophication effects on water ecosystems. The method of magnesium ammonium phosphate (MAP) crystallization was used to recover P from simulated swine wastewater, and the effects of three organic acids (citric acid, succinic acid and acetic acid) on P removal efficiency and rate at different pH values were investigated. The results indicated that the P removal efficiency was worst affected by citric acid in the optimal pH range of 9.0-10.5, followed by succinic acid and acetic acid, and the influencing extent of organic acids decreased with the increasing pH value. Due to the complexation between organic acid and Mg(2+)/NH4(+), all of three organic acids could inhibit the P removal rate at the beginning of the reaction, which showed positive correlation between the inhibition effects and the concentration of organic acids. The high concentration of citric acid could completely suppress the MAP crystallization reaction. Moreover, citric acid and succinic acid brought obvious effects on the morphology of the crystallized products. The experimental results also demonstrated that MAP crystals could be obtained in the presence of different kinds and concentrations of organic acids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Kinetic and isotherm studies for nickel (II) removal using novel mesoparticle graphene sand composite synthesised from sand and arenga palm sugar

NASA Astrophysics Data System (ADS)

Zularisam, A. W.; Wahida, Norul

2017-07-01

Nickel (II) is one of the most toxic contaminants recognised as a carcinogenic and mutagenic agent which needs complete removal from wastewater before disposal. In the present study, a novel adsorbent called mesoparticle graphene sand composite (MGSCaps) was synthesised from arenga palm sugar and sand by using a green, simple, low cost and efficient methodology. Subsequently, this composite was characterised and identified using field emission scanning electron microscope (FESEM), x-ray diffraction (XRD) and elemental mapping (EM). The adsorption process was investigated and optimised under the experimental parameters such as pH, contact time and bed depth. The results showed that the interaction between nickel (II) and MGSCaps was not ion to ion interaction hence removal of Ni (II) can be applied at any pH. The results were also exhibited the higher contact time and bed depth, the higher removal percentage of nickel (II) occurred. Adsorption kinetic data were modelled using Pseudo-first-order and Pseudo-second-order equation models. The experimental results indicated pseudo-second-order kinetic equation was most suitable to describe the experimental adsorption kinetics data with maximum capacity of 40% nickel (II) removal for the first hour. The equilibrium adsorption data was fitted with Langmuir, and Freundlich isotherms equations. The data suggested that the most fitted equation model is the Freundlich with correlation R2=0.9974. Based on the obtained results, it can be stated that the adsorption method using MGSCaps is an efficient, facile and reliable method for the removal of nickel (II) from waste water.

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields - BCOEL

NASA Technical Reports Server (NTRS)

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Sankaran, Subramanian; Taylor, Al; Julian, Ed; Robinson, Dale;

Critical analysis of adsorption data statistically

NASA Astrophysics Data System (ADS)

Kaushal, Achla; Singh, S. K.

2017-10-01

Experimental data can be presented, computed, and critically analysed in a different way using statistics. A variety of statistical tests are used to make decisions about the significance and validity of the experimental data. In the present study, adsorption was carried out to remove zinc ions from contaminated aqueous solution using mango leaf powder. The experimental data was analysed statistically by hypothesis testing applying t test, paired t test and Chi-square test to (a) test the optimum value of the process pH, (b) verify the success of experiment and (c) study the effect of adsorbent dose in zinc ion removal from aqueous solutions. Comparison of calculated and tabulated values of t and χ 2 showed the results in favour of the data collected from the experiment and this has been shown on probability charts. K value for Langmuir isotherm was 0.8582 and m value for Freundlich adsorption isotherm obtained was 0.725, both are <1, indicating favourable isotherms. Karl Pearson's correlation coefficient values for Langmuir and Freundlich adsorption isotherms were obtained as 0.99 and 0.95 respectively, which show higher degree of correlation between the variables. This validates the data obtained for adsorption of zinc ions from the contaminated aqueous solution with the help of mango leaf powder.

Adaptive restoration of river terrace vegetation through iterative experiments

USGS Publications Warehouse

Dela Cruz, Michelle P.; Beauchamp, Vanessa B.; Shafroth, Patrick B.; Decker, Cheryl E.; O’Neil, Aviva

2014-01-01

Restoration projects can involve a high degree of uncertainty and risk, which can ultimately result in failure. An adaptive restoration approach can reduce uncertainty through controlled, replicated experiments designed to test specific hypotheses and alternative management approaches. Key components of adaptive restoration include willingness of project managers to accept the risk inherent in experimentation, interest of researchers, availability of funding for experimentation and monitoring, and ability to restore sites as iterative experiments where results from early efforts can inform the design of later phases. This paper highlights an ongoing adaptive restoration project at Zion National Park (ZNP), aimed at reducing the cover of exotic annual Bromus on riparian terraces, and revegetating these areas with native plant species. Rather than using a trial-and-error approach, ZNP staff partnered with academic, government, and private-sector collaborators to conduct small-scale experiments to explicitly address uncertainties concerning biomass removal of annual bromes, herbicide application rates and timing, and effective seeding methods for native species. Adaptive restoration has succeeded at ZNP because managers accept the risk inherent in experimentation and ZNP personnel are committed to continue these projects over a several-year period. Techniques that result in exotic annual Bromus removal and restoration of native plant species at ZNP can be used as a starting point for adaptive restoration projects elsewhere in the region.

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields (BCOEL)

NASA Technical Reports Server (NTRS)

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Taylor, Al; Julian, Ed; Robinson, Dale; VanZandt, Dave

2001-01-01

The BCOEL project focuses on improving pool boiling heat transfer and bubble control in microgravity by exposing the fluid to electric fields. The electric fields induce a body force that can replace gravity in the low gravity environment, and enhance bubble removal from the heated surface. A better understanding of microgravity effects on boiling with and without electric fields is critical to the proper design of the phase-change-heat-removal equipment for use in spacebased applications. The microgravity experiments will focus on the visualization of bubble formation and shape during boiling. Heat fluxes on the boiling surface will be measured, and, together with the measured driving temperature differences, used to plot boiling curves for different electric field magnitudes. Bubble formation and boiling processes were found to be extremely sensitive to g-jitter. The duration of the experimental run is critical in order to achieve steady state in microgravity experiments. The International Space Station provides conditions suitable for such experiments. The experimental apparatus to be used in the study is described in the paper. The apparatus will be tested in the KC-135 first, and microgravity experiments will be conducted on board of the International Space Station using the Microgravity Science Glovebox as the experimental platform.

Successful removal of football helmet face-mask clips after 1 season of use.

PubMed

Scibek, Jason S; Gatti, Joseph M; McKenzie, Jennifer I

2012-01-01

Whereas many researchers have assessed the ability to remove loop straps in traditional face-mask attachment systems after at least 1 season of use, research in which the effectiveness of the Riddell Quick Release (QR) Face Guard Attachment System clip after 1 season has been assessed is limited. To examine the success rate of removing the QR clips after 1 season of use at the Football Championship Subdivision level. We hypothesized that 1 season of use would negatively affect the removal rate of the QR clip but repeated clip-removal trials would improve the removal rate. Retrospective, quasi-experimental design. Controlled laboratory study. Sixty-three football helmets from a National Collegiate Athletic Association Division I university located in western Pennsylvania used during the 2008 season were tested. Three certified athletic trainers (2 men, 1 woman; age = 31.3 ± 3.06 years, time certified = 9.42 ± 2.65 years) attempted to remove the QR clips from each helmet with the tool provided by the manufacturer. Helmets then were reassembled to allow each athletic trainer to attempt clip removal. The dependent variables were total left clips removed (TCR-L), total right clips removed (TCR-R), and total clips removed (TCR). Success rate of clip removal (SRCR) also was assessed. Percentages for TCR-L, TCR-R, and TCR were 100% (189 of 189), 96.30% (182 of 189), and 98.15% (371 of 378), respectively. A paired-samples t test revealed a difference between TCR-R and TCR-L (t(188) = 2.689, P = .008, μ(d) = 0.037, 95% confidence interval [CI] = 0.064, 0.010). The percentage for SRCR was 96.30% (n = 182), whereas SRCR percentages for trials 1, 2, and 3 were 95.24% (n = 60), 98.41% (n = 62), and 95.24% (n = 60), respectively, and did not represent a difference (F(2,186) = 0.588, P = .56, 95% (CI) = 0.94, 0.99). Our results indicated favorable and consistent success rates for QR clip removal after 1 season of use. Whereas the QR clip is an advancement in face-mask technology, continued examination of this system is required to ensure the highest level of function, allowing for effective management of the helmeted athlete.

Successful Removal of Football Helmet Face-Mask Clips After 1 Season of Use

PubMed Central

Scibek, Jason S.; Gatti, Joseph M.; McKenzie, Jennifer I.

2012-01-01

Context Whereas many researchers have assessed the ability to remove loop straps in traditional face-mask attachment systems after at least 1 season of use, research in which the effectiveness of the Riddell Quick Release (QR) Face Guard Attachment System clip after 1 season has been assessed is limited. Objective To examine the success rate of removing the QR clips after 1 season of use at the Football Championship Subdivision level. We hypothesized that 1 season of use would negatively affect the removal rate of the QR clip but repeated clip-removal trials would improve the removal rate. Design Retrospective, quasi-experimental design. Setting Controlled laboratory study. Patients or Other Participants Sixty-three football helmets from a National Collegiate Athletic Association Division I university located in western Pennsylvania used during the 2008 season were tested. Intervention(s) Three certified athletic trainers (2 men, 1 woman; age = 31.3 ± 3.06 years, time certified = 9.42 ± 2.65 years) attempted to remove the QR clips from each helmet with the tool provided by the manufacturer. Helmets then were reassembled to allow each athletic trainer to attempt clip removal. Main Outcome Measure(s) The dependent variables were total left clips removed (TCR-L), total right clips removed (TCR-R), and total clips removed (TCR). Success rate of clip removal (SRCR) also was assessed. Results Percentages for TCR-L, TCR-R, and TCR were 100% (189 of 189), 96.30% (182 of 189), and 98.15% (371 of 378), respectively. A paired-samples t test revealed a difference between TCR-R and TCR-L (t188 = −2.689, P = .008, μd = 0.037, 95% confidence interval [CI] = −0.064, −0.010). The percentage for SRCR was 96.30% (n = 182), whereas SRCR percentages for trials 1, 2, and 3 were 95.24% (n = 60), 98.41% (n = 62), and 95.24% (n = 60), respectively, and did not represent a difference (F2,186 = 0.588, P = .56, 95% CI = 0.94, 0.99). Conclusions Our results indicated favorable and consistent success rates for QR clip removal after 1 season of use. Whereas the QR clip is an advancement in face-mask technology, continued examination of this system is required to ensure the highest level of function, allowing for effective management of the helmeted athlete. PMID:22889659

Advanced oxidative processes and membrane separation for micropollutant removal from biotreated domestic wastewater.

PubMed

Silva, Larissa L S; Sales, Julio C S; Campos, Juacyara C; Bila, Daniele M; Fonseca, Fabiana V

2017-03-01

The presence of micropollutants in sewage is already widely known, as well as the effects caused by natural and synthetic hormones. Thus, it is necessary to apply treatments to remove them from water systems, such as advanced oxidation processes (AOPs) and membrane separation processes, which can oxidize and remove high concentrations of organic compounds. This work investigated the removal of 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and estriol (E3) from biotreated sewage. Reverse osmosis processes were conducted at three recoveries (50, 60, and 70 %). For E2 and EE2, the removals were affected by the recovery. The best results for RO were as follows: the E2 compound removal was 89 % for 60 % recovery and the EE2 compound removal was 57 % for 50 % recovery. The RO recovery did not impact the E3 removal. It was concluded that the interaction between the evaluated estrogens, and the membrane was the major factor for the hormone separation. The AOP treatment using H 2 O 2 /UV was carried out in two sampling campaigns. First, we evaluated the variation of UV doses (24.48, 73.44, 122.4, and 244.8 kJ m -2 ) with 18.8 mg L -1 of H 2 O 2 in the reaction. EE2 showed considerable removals (around 70 %). In order to optimize the results, an experimental design was applied. The best result was obtained with higher UV dose (122.4 kJ m -2 ) and lower H 2 O 2 concentration (4 mg L -1 ), achieving removal of 91 % for E3 and 100 % for E2 and EE2.

Experimental modal substructuring to couple and uncouple substructures with flexible fixtures and multi-point connections

NASA Astrophysics Data System (ADS)

Allen, Matthew S.; Mayes, Randall L.; Bergman, Elizabeth J.

2010-11-01

Modal substructuring or component mode synthesis (CMS) has been standard practice for many decades in the analytical realm, yet a number of significant difficulties have been encountered when attempting to combine experimentally derived modal models with analytical ones or when predicting the effect of structural modifications using experimental measurements. This work presents a new method that removes the effects of a flexible fixture from an experimentally obtained modal model. It can be viewed as an extension to the approach where rigid masses are removed from a structure. The approach presented here improves the modal basis of the substructure, so that it can be used to more accurately estimate the modal parameters of the built-up system. New types of constraints are also presented, which constrain the modal degrees of freedom of the substructures, avoiding the need to estimate the connection point displacements and rotations. These constraints together with the use of a flexible fixture enable a new approach for joining structures, especially those with statically indeterminate multi-point connections, such as two circular flanges that are joined by many more bolts than required to enforce compatibility if the substructures were rigid. Fixture design is discussed, one objective of which is to achieve a mass-loaded boundary condition that exercises the substructure at the connection point as it is in the built up system. The proposed approach is demonstrated with two examples using experimental measurements from laboratory systems. The first is a simple problem of joining two beams of differing lengths, while the second consists of a three-dimensional structure comprising a circular plate that is bolted at eight locations to a flange on a cylindrical structure. In both cases frequency response functions predicted by the substructuring methods agree well with those of the actual coupled structures over a significant range of frequencies.

The impact of user fees on health services utilization and infectious disease diagnoses in Neno District, Malawi: a longitudinal, quasi-experimental study.

PubMed

Watson, S I; Wroe, E B; Dunbar, E L; Mukherjee, J; Squire, S B; Nazimera, L; Dullie, L; Lilford, R J

2016-10-20

User fees have generally fallen out of favor across Africa, and they have been associated with reductions in access to healthcare. We examined the effects of the introduction and removal of user fees on outpatient attendances and new diagnoses of HIV, malaria, and tuberculosis in Neno District, Malawi where user fees were re-instated at three of 13 health centres in 2013 and subsequently removed at one of these in 2015. We conducted two analyses. Firstly, an unadjusted comparison of outpatient visits and new diagnoses over three periods between July 2012 and October 2015: during the period with no user fees, at the re-introduction of user fees at four centres, and after the removal of user fees at one centre. Secondly, we estimated a linear model of the effect of user fees on the outcome of interest that controlled for unobserved health centre effects, monthly effects, and a linear time trend. The introduction of user fees was associated with a change in total attendances of -68 % [95 % CI: -89 %, -12 %], similar reductions were observed for new malaria and HIV diagnoses. The removal of user fees was associated with an increase in total attendances of 352 % [213 %, 554 %] with similar increases for malaria diagnoses. The results were not sensitive to control group or model specification. User fees for outpatient healthcare services present a barrier to patients accessing healthcare and reduce detection of serious infectious diseases.