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Zhi Ping Xu - One of the best experts on this subject based on the ideXlab platform.
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mechanism of enhanced Nitrate Reduction via micro electrolysis at the powdered zero valent iron activated carbon interface
Journal of Colloid and Interface Science, 2014Co-Authors: Guangyu Song, Guangren Qian, Zhi Ping XuAbstract:Abstract Nitrate Reduction by zero-valent iron (Fe0) powder always works well only at controlled pH lower than 4 due to the formation of iron (hydr)oxides on its surface. Fe0 powder combined with activated carbon (AC), i.e., Fe0/AC micro-electrolysis system, was first introduced to enhance Nitrate Reduction in aqueous solution. Comparative study was carried out to investigate Nitrate Reduction by Fe0/AC system and Fe0 under near-neutral conditions, showing that the Fe0/AC system successfully reduced Nitrate even at initial pH 6 with the Reduction efficiency of up to 73%, whereas for Fe0 only ∼10%. The effect of Fe0 to AC mass ratio on Nitrate Reduction efficiency was examined. Easier Nitrate Reduction was achieved with more contact between Fe0 and AC as the result of decreasing Fe0 to AC mass ratio. Ferrous ion and oxidation–Reduction potential were measured to understand the mechanism of enhanced Nitrate Reduction by Fe0/AC micro-electrolysis. The results suggest that a relative potential difference drives much more electrons from Fe0 to AC, thus generating adsorbed atomic hydrogen which makes it possible for Nitrate to be reduced at near-neural pH. Fe0/AC micro-electrolysis thus presents a great potential for practical application in Nitrate wastewater treatment without excessive pH adjustment.
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Mechanism of enhanced Nitrate Reduction via micro-electrolysis at the powdered zero-valent iron/activated carbon interface
Journal of Colloid and Interface Science, 2014Co-Authors: Guangyu Song, Guangren Qian, Zhi Ping XuAbstract:Abstract Nitrate Reduction by zero-valent iron (Fe0) powder always works well only at controlled pH lower than 4 due to the formation of iron (hydr)oxides on its surface. Fe0 powder combined with activated carbon (AC), i.e., Fe0/AC micro-electrolysis system, was first introduced to enhance Nitrate Reduction in aqueous solution. Comparative study was carried out to investigate Nitrate Reduction by Fe0/AC system and Fe0 under near-neutral conditions, showing that the Fe0/AC system successfully reduced Nitrate even at initial pH 6 with the Reduction efficiency of up to 73%, whereas for Fe0 only ∼10%. The effect of Fe0 to AC mass ratio on Nitrate Reduction efficiency was examined. Easier Nitrate Reduction was achieved with more contact between Fe0 and AC as the result of decreasing Fe0 to AC mass ratio. Ferrous ion and oxidation–Reduction potential were measured to understand the mechanism of enhanced Nitrate Reduction by Fe0/AC micro-electrolysis. The results suggest that a relative potential difference drives much more electrons from Fe0 to AC, thus generating adsorbed atomic hydrogen which makes it possible for Nitrate to be reduced at near-neural pH. Fe0/AC micro-electrolysis thus presents a great potential for practical application in Nitrate wastewater treatment without excessive pH adjustment.
Anniet M. Laverman - One of the best experts on this subject based on the ideXlab platform.
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The effect of environmental and therapeutic concentrations of antibiotics on Nitrate Reduction rates in river sediment
Water research, 2013Co-Authors: Chen Yan, Josette Garnier, Céline Roose-amsaleg, Quoc Tuc Dinh, Marc Chevreuil, Pierre Labadie, Anniet M. LavermanAbstract:Abstract The use of antibiotics in both human and veterinary medicine has led to increased presence of these compounds and antibiotic resistance in the environment. In this study, the effect of low, environmentally relevant ( mg L−1) concentrations of vancomycin (VA), flumequine (FLU), and sulfamethoxazole (SMX) on Nitrate Reduction rates was studied in river sediments. Nitrate Reduction rates were determined by supplying intact sediments for several weeks with both Nitrate and antibiotics (ng L−1, μg L−1, and mg L−1 concentrations), including a non-amended control. Furthermore the concentrations of the three investigated antibiotics were measured in the initial (natural) sediments and the sediments supplied with the antibiotics. The antibiotic concentrations in the sediments decreased (on average 62% for FLU and 93% for SMX) during the experiments, indicating loss of antibiotics due to sorption or (bio) degradation. Nitrate Reduction rates were not affected by environmental concentrations of VA, FLU and SMX. FLU and SMX only partially inhibited Nitrate Reduction rates at high, therapeutic concentrations by 41 and 39% respectively. The three tested antibiotics significantly enhanced the production of nitrite, an intermediate in dissimilatory Nitrate Reduction. Nitrite production increased 1.9 and 1.4 fold for environmental VA concentrations (107 and 187 μg L−1 respectively), application of 58 mg L−1 SMX resulted in a 7.5 fold increase and augmented 16 and 8.5 fold in the presence of respectively 13 μg L−1 and 52 mg L−1 FLU. Even though inhibition of Nitrate Reduction rates was observed at therapeutic antibiotic concentrations, Nitrate Reduction proceeded under all experimental conditions, indicating the presence of resistance toward these antibiotics among the Nitrate reducing bacteria. The accumulation of nitrite suggests that the nitrite Reduction step was more affected than the overall Nitrate Reduction process.
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Nitrous oxide production kinetics during Nitrate Reduction in river sediments.
Water research, 2009Co-Authors: Anniet M. Laverman, Josette Garnier, Emmanuelle M. Mounier, Céline Roose-amsalegAbstract:Abstract A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of Nitrate and carbon concentrations on the kinetic parameters of Nitrate Reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum Nitrate Reduction rates ( R m ) ranged between 3.0 and 7.1 μg N g −1 h −1 , and affinity constant (K m ) ranged from 7.4 to 30.7 mg N-NO 3 − L −1 . These values were higher in slurry incubations with an R m of 37.9 μg N g −1 h −1 and a K m of 104 mg N-NO 3 − L −1 . Nitrous oxide production rates did not follow Michaelis–Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4 ng N g −1 h −1 for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting Nitrate Reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the Nitrate Reduction rates and were even negligible in slurries. Maximum Nitrate Reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting Nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the Nitrate Reduction rates).
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Potential rates and pathways of microbial Nitrate Reduction in coastal sediments.
FEMS microbiology ecology, 2006Co-Authors: Anniet M. Laverman, Philippe Van Cappellen, Debby Van Rotterdam-los, Céline Pallud, Jeffrey AbellAbstract:Nitrate Reduction plays a key role in the biogeochemical dynamics and microbial ecology of coastal sediments. Potential rates of Nitrate Reduction were measured on undisturbed sediment slices from two eutrophic coastal environments using flow-through reactors (FTR). Maximum potential Nitrate Reduction rates ranged over an order of magnitude, with values of up to 933 nmol cm−3 h−1, whereas affinity constants for NO3− fell mostly between 200 and 600 μM. Homogenized sediment slurries systematically yielded higher rates of Nitrate Reduction than the FTR experiments. Dentrification was the major Nitrate removal pathway in the sediments, although excess ammonium production indicated a contribution of dissimilatory Nitrate Reduction to ammonium under Nitrate-limiting conditions.
Céline Roose-amsaleg - One of the best experts on this subject based on the ideXlab platform.
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The effect of environmental and therapeutic concentrations of antibiotics on Nitrate Reduction rates in river sediment
Water research, 2013Co-Authors: Chen Yan, Josette Garnier, Céline Roose-amsaleg, Quoc Tuc Dinh, Marc Chevreuil, Pierre Labadie, Anniet M. LavermanAbstract:Abstract The use of antibiotics in both human and veterinary medicine has led to increased presence of these compounds and antibiotic resistance in the environment. In this study, the effect of low, environmentally relevant ( mg L−1) concentrations of vancomycin (VA), flumequine (FLU), and sulfamethoxazole (SMX) on Nitrate Reduction rates was studied in river sediments. Nitrate Reduction rates were determined by supplying intact sediments for several weeks with both Nitrate and antibiotics (ng L−1, μg L−1, and mg L−1 concentrations), including a non-amended control. Furthermore the concentrations of the three investigated antibiotics were measured in the initial (natural) sediments and the sediments supplied with the antibiotics. The antibiotic concentrations in the sediments decreased (on average 62% for FLU and 93% for SMX) during the experiments, indicating loss of antibiotics due to sorption or (bio) degradation. Nitrate Reduction rates were not affected by environmental concentrations of VA, FLU and SMX. FLU and SMX only partially inhibited Nitrate Reduction rates at high, therapeutic concentrations by 41 and 39% respectively. The three tested antibiotics significantly enhanced the production of nitrite, an intermediate in dissimilatory Nitrate Reduction. Nitrite production increased 1.9 and 1.4 fold for environmental VA concentrations (107 and 187 μg L−1 respectively), application of 58 mg L−1 SMX resulted in a 7.5 fold increase and augmented 16 and 8.5 fold in the presence of respectively 13 μg L−1 and 52 mg L−1 FLU. Even though inhibition of Nitrate Reduction rates was observed at therapeutic antibiotic concentrations, Nitrate Reduction proceeded under all experimental conditions, indicating the presence of resistance toward these antibiotics among the Nitrate reducing bacteria. The accumulation of nitrite suggests that the nitrite Reduction step was more affected than the overall Nitrate Reduction process.
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The effect of environmental and therapeutic concentrations of antibiotics on Nitrate Reduction rates in river sediment
Water Research, 2013Co-Authors: Chen Yan, Josette Garnier, Céline Roose-amsaleg, Quoc Tuc Dinh, Marc Chevreuil, Pierre Labadie, Anniet M. LauermanAbstract:The use of antibiotics in both human and veterinary medicine has led to increased presence of these compounds and antibiotic resistance in the environment. In this study, the effect of low, environmentally relevant (mg L-1) concentrations of vancomycin (VA), flumequine (FLU), and sulfamethoxazole (SMX) on Nitrate Reduction rates was studied in river sediments. Nitrate Reduction rates were determined by supplying intact sediments for several weeks with both Nitrate and antibiotics (ng L-1, mu g L-1, and mg L-1 concentrations), including a non-amended control. Furthermore the concentrations of the three investigated antibiotics were measured in the initial (natural) sediments and the sediments supplied with the antibiotics. The antibiotic concentrations in the sediments decreased (on average 62% for FLU and 93% for SMX) during the experiments, indicating loss of antibiotics due to sorption or (bio) degradation. Nitrate Reduction rates were not affected by environmental concentrations of VA, FLU and SMX. FLU and SMX only partially inhibited Nitrate Reduction rates at high, therapeutic concentrations by 41 and 39% respectively. The three tested antibiotics significantly enhanced the production of nitrite, an intermediate in dissimilatory Nitrate Reduction. Nitrite production increased 1.9 and 1.4 fold for environmental VA concentrations (107 and 187 mu g L-1 respectively), application of 58 mg L-1 SMX resulted in a 7.5 fold increase and augmented 16 and 8.5 fold in the presence of respectively 13 mu g L-1 and 52 mg L-1 FLU. Even though inhibition of Nitrate Reduction rates was observed at therapeutic antibiotic concentrations, Nitrate Reduction proceeded under all experimental conditions, indicating the presence of resistance toward these antibiotics among the Nitrate reducing bacteria. The accumulation of nitrite suggests that the nitrite Reduction step was more affected than the overall Nitrate Reduction process. (C) 2013 Elsevier Ltd. All rights reserved.
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Nitrous oxide production kinetics during Nitrate Reduction in river sediments.
Water research, 2009Co-Authors: Anniet M. Laverman, Josette Garnier, Emmanuelle M. Mounier, Céline Roose-amsalegAbstract:Abstract A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of Nitrate and carbon concentrations on the kinetic parameters of Nitrate Reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum Nitrate Reduction rates ( R m ) ranged between 3.0 and 7.1 μg N g −1 h −1 , and affinity constant (K m ) ranged from 7.4 to 30.7 mg N-NO 3 − L −1 . These values were higher in slurry incubations with an R m of 37.9 μg N g −1 h −1 and a K m of 104 mg N-NO 3 − L −1 . Nitrous oxide production rates did not follow Michaelis–Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4 ng N g −1 h −1 for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting Nitrate Reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the Nitrate Reduction rates and were even negligible in slurries. Maximum Nitrate Reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting Nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the Nitrate Reduction rates).
Guangyu Song - One of the best experts on this subject based on the ideXlab platform.
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mechanism of enhanced Nitrate Reduction via micro electrolysis at the powdered zero valent iron activated carbon interface
Journal of Colloid and Interface Science, 2014Co-Authors: Guangyu Song, Guangren Qian, Zhi Ping XuAbstract:Abstract Nitrate Reduction by zero-valent iron (Fe0) powder always works well only at controlled pH lower than 4 due to the formation of iron (hydr)oxides on its surface. Fe0 powder combined with activated carbon (AC), i.e., Fe0/AC micro-electrolysis system, was first introduced to enhance Nitrate Reduction in aqueous solution. Comparative study was carried out to investigate Nitrate Reduction by Fe0/AC system and Fe0 under near-neutral conditions, showing that the Fe0/AC system successfully reduced Nitrate even at initial pH 6 with the Reduction efficiency of up to 73%, whereas for Fe0 only ∼10%. The effect of Fe0 to AC mass ratio on Nitrate Reduction efficiency was examined. Easier Nitrate Reduction was achieved with more contact between Fe0 and AC as the result of decreasing Fe0 to AC mass ratio. Ferrous ion and oxidation–Reduction potential were measured to understand the mechanism of enhanced Nitrate Reduction by Fe0/AC micro-electrolysis. The results suggest that a relative potential difference drives much more electrons from Fe0 to AC, thus generating adsorbed atomic hydrogen which makes it possible for Nitrate to be reduced at near-neural pH. Fe0/AC micro-electrolysis thus presents a great potential for practical application in Nitrate wastewater treatment without excessive pH adjustment.
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Mechanism of enhanced Nitrate Reduction via micro-electrolysis at the powdered zero-valent iron/activated carbon interface
Journal of Colloid and Interface Science, 2014Co-Authors: Guangyu Song, Guangren Qian, Zhi Ping XuAbstract:Abstract Nitrate Reduction by zero-valent iron (Fe0) powder always works well only at controlled pH lower than 4 due to the formation of iron (hydr)oxides on its surface. Fe0 powder combined with activated carbon (AC), i.e., Fe0/AC micro-electrolysis system, was first introduced to enhance Nitrate Reduction in aqueous solution. Comparative study was carried out to investigate Nitrate Reduction by Fe0/AC system and Fe0 under near-neutral conditions, showing that the Fe0/AC system successfully reduced Nitrate even at initial pH 6 with the Reduction efficiency of up to 73%, whereas for Fe0 only ∼10%. The effect of Fe0 to AC mass ratio on Nitrate Reduction efficiency was examined. Easier Nitrate Reduction was achieved with more contact between Fe0 and AC as the result of decreasing Fe0 to AC mass ratio. Ferrous ion and oxidation–Reduction potential were measured to understand the mechanism of enhanced Nitrate Reduction by Fe0/AC micro-electrolysis. The results suggest that a relative potential difference drives much more electrons from Fe0 to AC, thus generating adsorbed atomic hydrogen which makes it possible for Nitrate to be reduced at near-neural pH. Fe0/AC micro-electrolysis thus presents a great potential for practical application in Nitrate wastewater treatment without excessive pH adjustment.
Ray L. Frost - One of the best experts on this subject based on the ideXlab platform.
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Nitrate Reduction over nanoscale zero-valent iron prepared by hydrogen Reduction of goethite
Science & Engineering Faculty, 2012Co-Authors: Haibo Liu, Tianhu Chen, Dongyin Chang, Dong Chen, Yunfu Liu, Peng Yuan, Ray L. FrostAbstract:Nitrate Reduction with nanoscale zero-valent iron (NZVI) was reported as a potential technology to remove Nitrate from Nitrate-contaminated water. In this paper, Nitrate Reduction with NZVI prepared by hydrogen Reduction of natural goethite (NZVI-N, -N represents natural goethite) and hydrothermal goethite (NZVI-H, -H represents hydrothermal goethite) was conducted. Besides, the effects of reaction time, Nitrate concentration, iron-to-Nitrate ratio on Nitrate removal rate over NZVI-H and NZVI-N were investigated. To prove their excellent Nitrate Reduction capacities, NZVI-N and NZVI-H were compared with ordinary zero-valent iron (OZVI-N) through the static experiments. Based on all above investigations, the mechanism of Nitrate Reduction with NZVI-N was proposed. The result showed that reaction time, Nitrate concentration, iron-to-Nitrate ratio played an important role in Nitrate Reduction by NZVI-N and NZVI-H. Compared with OZVI, NZVI-N and NZVI-H showed little relationship with pH. And NZVI-N for Nitrate composition offers a higher stability than NZVI-H because of the existence of Al-substitution. Furthermore, NZVI-N, prepared by hydrogen Reduction of goethite, has higher activity for Nitrate Reduction and the products contain hydrogen, nitrogen, NH 4 +, a little nitrite, but no NOx, meanwhile NZVI-N was oxidized to Fe 2+. It is a relatively easy and cost-effective method for Nitrate removal, so NZVI-N reducing Nitrate has a great potential application in Nitrate removal of groundwater. © 2012 Elsevier B.V.
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Nitrate Reduction over nanoscale zero-valent iron prepared by hydrogen Reduction of goethite
Materials Chemistry and Physics, 2012Co-Authors: Haibo Liu, Tianhu Chen, Dongyin Chang, Dong Chen, Yunfu Liu, Peng Yuan, Ray L. FrostAbstract:Abstract Nitrate Reduction with nanoscale zero-valent iron (NZVI) was reported as a potential technology to remove Nitrate from Nitrate-contaminated water. In this paper, Nitrate Reduction with NZVI prepared by hydrogen Reduction of natural goethite (NZVI-N, -N represents natural goethite) and hydrothermal goethite (NZVI-H, -H represents hydrothermal goethite) was conducted. Besides, the effects of reaction time, Nitrate concentration, iron-to-Nitrate ratio on Nitrate removal rate over NZVI-H and NZVI-N were investigated. To prove their excellent Nitrate Reduction capacities, NZVI-N and NZVI-H were compared with ordinary zero-valent iron (OZVI-N) through the static experiments. Based on all above investigations, the mechanism of Nitrate Reduction with NZVI-N was proposed. The result showed that reaction time, Nitrate concentration, iron-to-Nitrate ratio played an important role in Nitrate Reduction by NZVI-N and NZVI-H. Compared with OZVI, NZVI-N and NZVI-H showed little relationship with pH. And NZVI-N for Nitrate composition offers a higher stability than NZVI-H because of the existence of Al-substitution. Furthermore, NZVI-N, prepared by hydrogen Reduction of goethite, has higher activity for Nitrate Reduction and the products contain hydrogen, nitrogen, NH4+, a little nitrite, but no NOx, meanwhile NZVI-N was oxidized to Fe2+. It is a relatively easy and cost-effective method for Nitrate removal, so NZVI-N reducing Nitrate has a great potential application in Nitrate removal of groundwater.