Design and optimization of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOPs) using hydrogen peroxide (H2O2) must consider both system configuration and chemical kinetics. Alternative approaches to modeling AOP systems have been proposed in the literature; yet, due to the complex nature of the reactions involved, the literature lacks clarity in the appropriate selection of a modeling approach to help define the UV/AOP system performance. Computational fluid dynamics (CFD) was compared to the numerical solution of a system of ordinary differential equations describing the reaction mechanism for hydroxyl radical production and methylene blue destruction and to a UV dose distribution analysis produced by a Lagrangian particle track in CFD with a given dose–response curve. Similar analyses were also performed to simulate the destruction of tris(2-chloroethyl) phosphate (TCEP) and tributyl phosphate (TBP), in two different photoreactors. To validate the simulations, the results of the models were compared to pilot reactor trials for methylene blue bleaching and literature data for TCEP and TBP. Modeling results suggest that the agreement of both CFD Eulerian and Lagrangian approaches to simulating the UV/H2O2 AOP is a function of reactor design, the water matrix, and operating conditions.
{"title":"Computational fluid dynamics modeling alternatives for UV-initiated advanced oxidation processes","authors":"J. Ducoste, Scott M. Alpert","doi":"10.2166/WQRJC.2014.035","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.035","url":null,"abstract":"Design and optimization of ultraviolet-initiated (UV-initiated) advanced oxidation processes (AOPs) using hydrogen peroxide (H2O2) must consider both system configuration and chemical kinetics. Alternative approaches to modeling AOP systems have been proposed in the literature; yet, due to the complex nature of the reactions involved, the literature lacks clarity in the appropriate selection of a modeling approach to help define the UV/AOP system performance. Computational fluid dynamics (CFD) was compared to the numerical solution of a system of ordinary differential equations describing the reaction mechanism for hydroxyl radical production and methylene blue destruction and to a UV dose distribution analysis produced by a Lagrangian particle track in CFD with a given dose–response curve. Similar analyses were also performed to simulate the destruction of tris(2-chloroethyl) phosphate (TCEP) and tributyl phosphate (TBP), in two different photoreactors. To validate the simulations, the results of the models were compared to pilot reactor trials for methylene blue bleaching and literature data for TCEP and TBP. Modeling results suggest that the agreement of both CFD Eulerian and Lagrangian approaches to simulating the UV/H2O2 AOP is a function of reactor design, the water matrix, and operating conditions.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Computational fluid dynamics in water and wastewater processes","authors":"I. Nopens, D. Santoro, C. Haas, P. Vanrolleghem","doi":"10.2166/WQRJC.2014.101","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.101","url":null,"abstract":"","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this research was to study the efficacy of the marine brown alga Sargassum glaucescens in batch removal of Zn(II) from wastewater and seawater. For these experiments, a dried biomass was used to adsorb Zn(II) from aqueous solutions. The effects of varying pH, biomass weight, retention time and initial concentration of Zn(II) were studied. The maximum efficiency of Zn(II) removal obtained was 90.00%. The experimental adsorption data were fitted to the Freundlich adsorption model. A pseudo-second-order model was found to offer the best analysis of Zn(II) uptake. Kinetic studies showed that a biomass formed of marine-dried S. glaucescens exhibited high biosorption capacity. A solution pH of 5.0 was found to be optimal for adsorption. Results showed that removal of Zn(II), increased to 90.00% with increasing contact time, increasing pH (to 5.0) and decreasing adsorbent amount. The equilibrium adsorption data are fitted to the Freundlich isotherm model and pseudo-second-order kinetic models. Therefore, brown algae Sargassum glaucescens was an economical adsorbent.
{"title":"Evaluation of the marine alga Sargassum glaucescens for the adsorption of Zn(II) from aqueous solutions","authors":"A. Esmaeili, M. Darvish","doi":"10.2166/WQRJC.2014.006","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.006","url":null,"abstract":"The objective of this research was to study the efficacy of the marine brown alga Sargassum glaucescens in batch removal of Zn(II) from wastewater and seawater. For these experiments, a dried biomass was used to adsorb Zn(II) from aqueous solutions. The effects of varying pH, biomass weight, retention time and initial concentration of Zn(II) were studied. The maximum efficiency of Zn(II) removal obtained was 90.00%. The experimental adsorption data were fitted to the Freundlich adsorption model. A pseudo-second-order model was found to offer the best analysis of Zn(II) uptake. Kinetic studies showed that a biomass formed of marine-dried S. glaucescens exhibited high biosorption capacity. A solution pH of 5.0 was found to be optimal for adsorption. Results showed that removal of Zn(II), increased to 90.00% with increasing contact time, increasing pH (to 5.0) and decreasing adsorbent amount. The equilibrium adsorption data are fitted to the Freundlich isotherm model and pseudo-second-order kinetic models. Therefore, brown algae Sargassum glaucescens was an economical adsorbent.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents preliminary results of settling tests on anaerobic sludge from food-processing wastewater treatment, using 2, 4, and 8 L cylinders. A sedimentation model from the literature was applied to the sedimentation data. The specific settling velocities for the 2 and 4 L cylinders did not differ ( t -test; P = 0.896), therefore the data were pooled. The specific settling velocity mean was nearly three times higher ( P = 0.027) for the 8 L cylinder (21.03 × 10 −4 ± 6.27 × 10 −4 m/s) than the pooled smaller cylinder size (7.29 × 10 −4 ± 2.32 × 10 −4 m/s). Measurement challenges were encountered while working with the 8 L cylinder. Given that tests using a 1 L cylinder resulted in sludge compression, the results indicate that use of both 2 and 4 L cylinders is feasible for lab-scale measurement of sludge settling.
{"title":"Settling of food-processing anaerobic sludge","authors":"A. Rodriguez-Prado, L. Ripley, J. Garcia-Orozco","doi":"10.2166/wqrjc.2014.003","DOIUrl":"https://doi.org/10.2166/wqrjc.2014.003","url":null,"abstract":"This paper presents preliminary results of settling tests on anaerobic sludge from food-processing wastewater treatment, using 2, 4, and 8 L cylinders. A sedimentation model from the literature was applied to the sedimentation data. The specific settling velocities for the 2 and 4 L cylinders did not differ ( t -test; P = 0.896), therefore the data were pooled. The specific settling velocity mean was nearly three times higher ( P = 0.027) for the 8 L cylinder (21.03 × 10 −4 ± 6.27 × 10 −4 m/s) than the pooled smaller cylinder size (7.29 × 10 −4 ± 2.32 × 10 −4 m/s). Measurement challenges were encountered while working with the 8 L cylinder. Given that tests using a 1 L cylinder resulted in sludge compression, the results indicate that use of both 2 and 4 L cylinders is feasible for lab-scale measurement of sludge settling.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/wqrjc.2014.003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
George G. Songulashvili, G. Jimenéz-Tobón, C. Jaspers, J. Gratia, F. Debaste, M. Penninckx
The evaluation of continuous elimination and transformation of toxic endocrine disruptors micropollutants (MPs) (Bisphenol A, Nonylphenol [NP] and Triclosan [TCS]) using immobilized laccase of Coriolopsis sp. showed the high potential of this laccase as a bio-agent for the elimination and transformation process of selected MPs. A toxicology test using Escherichia coli has shown that toxicity completely disappeared after transformation and elimination of Bisphenol A, while in cases of NP and TCS 95% and 90% toxicity, respectively, disappeared. As compared to initial activity, immobilized laccase activity remained practically constant at the end of several runs of elimination and transformation processes of MPs. This feature is promising for the use of immobilized Coriolopsis sp. laccase in a future industrial depollution process.
{"title":"Immobilized Coriolopsis sp. laccase for continuous elimination and transformation of phenolic micropollutants","authors":"George G. Songulashvili, G. Jimenéz-Tobón, C. Jaspers, J. Gratia, F. Debaste, M. Penninckx","doi":"10.2166/WQRJC.2014.113","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.113","url":null,"abstract":"The evaluation of continuous elimination and transformation of toxic endocrine disruptors micropollutants (MPs) (Bisphenol A, Nonylphenol [NP] and Triclosan [TCS]) using immobilized laccase of Coriolopsis sp. showed the high potential of this laccase as a bio-agent for the elimination and transformation process of selected MPs. A toxicology test using Escherichia coli has shown that toxicity completely disappeared after transformation and elimination of Bisphenol A, while in cases of NP and TCS 95% and 90% toxicity, respectively, disappeared. As compared to initial activity, immobilized laccase activity remained practically constant at the end of several runs of elimination and transformation processes of MPs. This feature is promising for the use of immobilized Coriolopsis sp. laccase in a future industrial depollution process.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.113","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67980866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fan Liu, Guanxing Huang, Jichao Sun, Ji-hong Jing, Ying Zhang
To elucidate the distribution of arsenic in shallow aquifers of the Guangzhou region (South China), 85 groundwater samples were collected and 18 chemical parameters of them were analyzed. The arsenic concentration of groundwater ranged from below detection limit to 0.13 mg/L. The results showed that those areas with high arsenic concentration were characterized by porous aquifers, low-lying, relief topography and close proximity to fault belt and rivers. The reductive dissolution of Fe (hydr)oxides is the main control mechanism for arsenic enrichment in the river delta region where groundwater is mainly characterized by a reducing environment. This mechanism was well embodied in the areas with these geological and geographical features. Agricultural fertilizer could produce high levels of nitrate in groundwater and the reduction of it could restrain the enrichment of arsenic. Industrial effluents, sewage irrigation and the probable leakage from sewers could promote the arsenic content in groundwater by lateral flow and infiltration. In addition, the effect of ion competition between phosphate and arsenic occurred in sewer leakage areas characterized by middle-high construction leading to the elevation of arsenic concentrations. The arsenic distribution in groundwater was caused by these natural and anthropogenic factors jointly.
{"title":"Distribution of arsenic in shallow aquifers of Guangzhou region, China: natural and anthropogenic impacts","authors":"Fan Liu, Guanxing Huang, Jichao Sun, Ji-hong Jing, Ying Zhang","doi":"10.2166/WQRJC.2014.014","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.014","url":null,"abstract":"To elucidate the distribution of arsenic in shallow aquifers of the Guangzhou region (South China), 85 groundwater samples were collected and 18 chemical parameters of them were analyzed. The arsenic concentration of groundwater ranged from below detection limit to 0.13 mg/L. The results showed that those areas with high arsenic concentration were characterized by porous aquifers, low-lying, relief topography and close proximity to fault belt and rivers. The reductive dissolution of Fe (hydr)oxides is the main control mechanism for arsenic enrichment in the river delta region where groundwater is mainly characterized by a reducing environment. This mechanism was well embodied in the areas with these geological and geographical features. Agricultural fertilizer could produce high levels of nitrate in groundwater and the reduction of it could restrain the enrichment of arsenic. Industrial effluents, sewage irrigation and the probable leakage from sewers could promote the arsenic content in groundwater by lateral flow and infiltration. In addition, the effect of ion competition between phosphate and arsenic occurred in sewer leakage areas characterized by middle-high construction leading to the elevation of arsenic concentrations. The arsenic distribution in groundwater was caused by these natural and anthropogenic factors jointly.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A hydrologic and water quality model is sought to establish an approach to land management decisions for a Canadian Army training base. Training areas are subjected to high levels of persistent activity creating unique land cover and land-use disturbances. Deforestation, complex road networks, off-road manoeuvres, and vehicle stream crossings are among major anthropogenic activities observed to affect these landscapes. Expanding, preserving and improving the quality of these areas to host training activities for future generations is critical to maintain operational effectiveness. Inclusive to this objective is minimizing resultant environmental degradation, principally in the form of hydrologic fluctuations, excess erosion, and sedimentation of aquatic environments. Application of the Soil Water Assessment Tool (SWAT) was assessed for its ability to simulate hydrologic and water quality conditions observed in military landscapes at 5th Canadian Division Support Base (5 CDSB) Gagetown, New Brunswick. Despite some limitations, this model adequately simulated three partial years of daily watershed outflow ( NSE = 0.47–0.79, R 2 = 0.50–0.88) and adequately predicted suspended sediment yields during the observation periods (% d = 6–47%) for one highly disturbed sub-watershed in Gagetown. Further development of this model may help guide decisions to develop or decommission training areas, guide land management practices and prioritize select landscape mitigation efforts.
{"title":"Applying the Soil Water Assessment Tool to 5th Canadian Division Support Base Gagetown","authors":"S. Burdett, M. Hulley, Andy Smith","doi":"10.2166/WQRJC.2014.012","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.012","url":null,"abstract":"A hydrologic and water quality model is sought to establish an approach to land management decisions for a Canadian Army training base. Training areas are subjected to high levels of persistent activity creating unique land cover and land-use disturbances. Deforestation, complex road networks, off-road manoeuvres, and vehicle stream crossings are among major anthropogenic activities observed to affect these landscapes. Expanding, preserving and improving the quality of these areas to host training activities for future generations is critical to maintain operational effectiveness. Inclusive to this objective is minimizing resultant environmental degradation, principally in the form of hydrologic fluctuations, excess erosion, and sedimentation of aquatic environments. Application of the Soil Water Assessment Tool (SWAT) was assessed for its ability to simulate hydrologic and water quality conditions observed in military landscapes at 5th Canadian Division Support Base (5 CDSB) Gagetown, New Brunswick. Despite some limitations, this model adequately simulated three partial years of daily watershed outflow ( NSE = 0.47–0.79, R 2 = 0.50–0.88) and adequately predicted suspended sediment yields during the observation periods (% d = 6–47%) for one highly disturbed sub-watershed in Gagetown. Further development of this model may help guide decisions to develop or decommission training areas, guide land management practices and prioritize select landscape mitigation efforts.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Masse, M. Mondor, J. Puig-Bargués, L. Deschênes, G. Talbot
The increasing use of membrane technology to treat highly charged wastewaters has renewed interest in the development of adequate cleaning strategies. This study investigated the efficiency of various chemicals, including acids, bases, surfactants, chelators, salts, enzymes, and oxidants, to clean two reverse osmosis membranes (BW30 and SW30XLE) filtering one swine wastewater pretreated by aerobic biofiltration and two swine wastewaters pretreated by mechanical solid–liquid separation. Mixes of anionic surfactants and chelators provided optimal cleaning efficiency for all fouled membranes and all effluents. A solution containing 10 mM EDTA (ethylenediamine tetraacetic acid) and 10 mM SDS (sodium dodecyl sulfate) yielded the highest flux recovery after one 20-h fouling cycle with the BW30 membrane and three consecutive fouling–cleaning cycles with the SW30XLE membrane. The EDTA + SDS solution also resulted in the lowest residual protein concentration on membrane surface and the optimal restoration of the initial contact angle of the membranes. Conversely, 75 mM acid citric and 100 mM NaCl solutions were the least efficient to clean the fouled membranes. Most chemical solutions were more efficient to clean the fouling layer generated by the swine wastewater pretreated by aerobic biofiltration than mechanical separation.
越来越多地使用膜技术来处理高电荷废水，重新引起了人们对开发适当的清洁策略的兴趣。本研究考察了酸、碱、表面活性剂、螯合剂、盐、酶和氧化剂等多种化学物质对两种反渗透膜(BW30和SW30XLE)的净化效果，分别过滤一种好氧生物过滤预处理的猪废水和两种机械固液分离预处理的猪废水。阴离子表面活性剂和螯合剂的混合物为所有污染的膜和所有流出物提供了最佳的清洁效率。含有10 mM EDTA(乙二胺四乙酸)和10 mM SDS(十二烷基硫酸钠)的溶液在BW30膜的一个20小时的污染循环和SW30XLE膜的连续三个污染-清洗循环后的通量回收率最高。EDTA + SDS溶液在膜表面的残留蛋白浓度最低，膜的初始接触角恢复最佳。相反，75 mM柠檬酸和100 mM NaCl溶液对污染膜的清洁效率最低。大多数化学溶液对好氧生物过滤预处理的生猪废水所产生的污染层的净化效果优于机械分离。
{"title":"The efficiency of various chemical solutions to clean reverse osmosis membranes processing swine wastewater","authors":"L. Masse, M. Mondor, J. Puig-Bargués, L. Deschênes, G. Talbot","doi":"10.2166/WQRJC.2014.008","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.008","url":null,"abstract":"The increasing use of membrane technology to treat highly charged wastewaters has renewed interest in the development of adequate cleaning strategies. This study investigated the efficiency of various chemicals, including acids, bases, surfactants, chelators, salts, enzymes, and oxidants, to clean two reverse osmosis membranes (BW30 and SW30XLE) filtering one swine wastewater pretreated by aerobic biofiltration and two swine wastewaters pretreated by mechanical solid–liquid separation. Mixes of anionic surfactants and chelators provided optimal cleaning efficiency for all fouled membranes and all effluents. A solution containing 10 mM EDTA (ethylenediamine tetraacetic acid) and 10 mM SDS (sodium dodecyl sulfate) yielded the highest flux recovery after one 20-h fouling cycle with the BW30 membrane and three consecutive fouling–cleaning cycles with the SW30XLE membrane. The EDTA + SDS solution also resulted in the lowest residual protein concentration on membrane surface and the optimal restoration of the initial contact angle of the membranes. Conversely, 75 mM acid citric and 100 mM NaCl solutions were the least efficient to clean the fouled membranes. Most chemical solutions were more efficient to clean the fouling layer generated by the swine wastewater pretreated by aerobic biofiltration than mechanical separation.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67979852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rui Wang, Liang Chen, Fei Liu, H. Chen, Jia Zhang, Ming Chen
Bioreduction of perchlorate and nitrate by perchlorate-reducing microorganisms (PRMs) is an environmentally friendly, economic, and efficient technology to treat mixed plumes composed of these substances. The influence of perchlorate, nitrate, and denitrification intermediates on PRM activity is a critical factor, which may affect the efficiency of treatment technology. This study investigated the inhibition of nitrate and the intermediate (nitrite) accumulated during the denitrification process on perchlorate bioreduction via a batch-type experiment. From the experiment, it was found that perchlorate had no effect on the denitrification process and that the reduction rate of perchlorate could be improved when NO 3 − -N/ClO 4 − ≤1.2. However, a negative effect of nitrate on perchlorate reduction was observed when NO 3 − -N/ClO 4 − >1.2 with an accumulation of 18.0 mg NO 2 − -N /L. This negative effect increased with the concentration of nitrate. Moreover, nitrite from the denitrification process had a similar negative effect on perchlorate reduction. Bioreduction of perchlorate was not started until nitrite was totally reduced, and a 2–13 day lag period was observed for perchlorate reduction after nitrite depletion.
{"title":"Inhibition of nitrate and the accumulated denitrification intermediate (nitrite) on perchlorate bioreduction","authors":"Rui Wang, Liang Chen, Fei Liu, H. Chen, Jia Zhang, Ming Chen","doi":"10.2166/WQRJC.2014.010","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.010","url":null,"abstract":"Bioreduction of perchlorate and nitrate by perchlorate-reducing microorganisms (PRMs) is an environmentally friendly, economic, and efficient technology to treat mixed plumes composed of these substances. The influence of perchlorate, nitrate, and denitrification intermediates on PRM activity is a critical factor, which may affect the efficiency of treatment technology. This study investigated the inhibition of nitrate and the intermediate (nitrite) accumulated during the denitrification process on perchlorate bioreduction via a batch-type experiment. From the experiment, it was found that perchlorate had no effect on the denitrification process and that the reduction rate of perchlorate could be improved when NO 3 − -N/ClO 4 − ≤1.2. However, a negative effect of nitrate on perchlorate reduction was observed when NO 3 − -N/ClO 4 − >1.2 with an accumulation of 18.0 mg NO 2 − -N /L. This negative effect increased with the concentration of nitrate. Moreover, nitrite from the denitrification process had a similar negative effect on perchlorate reduction. Bioreduction of perchlorate was not started until nitrite was totally reduced, and a 2–13 day lag period was observed for perchlorate reduction after nitrite depletion.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adsorption of phosphate onto construction solid waste (CSW) was investigated in a batch system. CSW as an inescapable by-product of the construction and demolition process, was used as a composite adsorbent for the removal of phosphate in this study. The adsorption kinetics was investigated under various parameters such as contact time, pH, CSW dosage, initial phosphate concentration and particle size. Greater percentage of phosphate was removed with decrease in the initial concentration and increase in the amount of CSW used. Adsorption of phosphate was pH dependent, and maximum phosphate immobilisation capacity was obtained in alkaline condition. Lagergren first-order, second-order, intra-particle diffusion and external diffusion model were used to test the experimental data. Kinetic analysis showed that the adsorption was best fitted with the pseudo-second-order kinetic model. Adsorption mechanism studies revealed that both external mass transfer and intra-particle diffusion had rate limiting effects on the removal process. These results demonstrated that the CSW could be used as a low-cost adsorbent media for phosphate removal, and the data were relevant for optimal design of wastewater treatment plants.
{"title":"Kinetic studies of phosphate adsorption onto construction solid waste (CSW)","authors":"C. Liu, Y. Yang, N. Wan","doi":"10.2166/WQRJC.2014.013","DOIUrl":"https://doi.org/10.2166/WQRJC.2014.013","url":null,"abstract":"Adsorption of phosphate onto construction solid waste (CSW) was investigated in a batch system. CSW as an inescapable by-product of the construction and demolition process, was used as a composite adsorbent for the removal of phosphate in this study. The adsorption kinetics was investigated under various parameters such as contact time, pH, CSW dosage, initial phosphate concentration and particle size. Greater percentage of phosphate was removed with decrease in the initial concentration and increase in the amount of CSW used. Adsorption of phosphate was pH dependent, and maximum phosphate immobilisation capacity was obtained in alkaline condition. Lagergren first-order, second-order, intra-particle diffusion and external diffusion model were used to test the experimental data. Kinetic analysis showed that the adsorption was best fitted with the pseudo-second-order kinetic model. Adsorption mechanism studies revealed that both external mass transfer and intra-particle diffusion had rate limiting effects on the removal process. These results demonstrated that the CSW could be used as a low-cost adsorbent media for phosphate removal, and the data were relevant for optimal design of wastewater treatment plants.","PeriodicalId":54407,"journal":{"name":"Water Quality Research Journal of Canada","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2014-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2166/WQRJC.2014.013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67981161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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