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I A Ololade - One of the best experts on this subject based on the ideXlab platform.
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influence of oxic Anoxic Condition on sorption behavior of pfos in sediment
Chemosphere, 2016Co-Authors: I A Ololade, Qin ZhouAbstract:Sediment components and redox properties change with oxic/Anoxic Condition, which affect the environmental transport of perfluorooctane sulfonate (PFOS). Herein, the influence of oxic/Anoxic Condition on the variation of redox and residual components of sediments, where organic matter, iron and manganese oxides are separated from the original sediment collected from Lake Taihu, China, are investigated. Meanwhile, the distinguishing sorption behaviors of PFOS on various residual sediments under oxic and Anoxic Condition are studied. Sediment after extracting iron and manganese (S-FeMn), which possessed the highest organic carbon (0.99%), had the highest affinity for PFOS under oxic Condition. However, Anoxic environment resulted in an increase of the pH, dissolving of organic carbon and de-protonation of S-FeMn, which caused the lower sorption capacity of PFOS on S-FeMn. Sediment after extracting manganese (S-Mn) had the higher sorption ability in Anoxic environment because the Fe2+ from S-Mn provided more effective electrostatic sites for anionic PFOS. When the environment changed to oxic Condition, the iron existed as trivalent form in S-Mn, which resulted in a block of effective sorption site and reduced the sorption amounts of PFOS. The higher percentage of manganese oxides restrained the sorption of PFOS. Hence, whether or not oxic/Anoxic Condition promoted the PFOS sorption depended on both the percentage and form of various components in the sediment. The study generated further insight into the environmental transport of PFOS in the sediments with different properties and the wetland system, where oxic/Anoxic subsurface flow was constructed.
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Influence of oxic/Anoxic Condition on sorption behavior of PFOS in sediment.
Chemosphere, 2015Co-Authors: I A Ololade, Qin Zhou, Gang PanAbstract:Sediment components and redox properties change with oxic/Anoxic Condition, which affect the environmental transport of perfluorooctane sulfonate (PFOS). Herein, the influence of oxic/Anoxic Condition on the variation of redox and residual components of sediments, where organic matter, iron and manganese oxides are separated from the original sediment collected from Lake Taihu, China, are investigated. Meanwhile, the distinguishing sorption behaviors of PFOS on various residual sediments under oxic and Anoxic Condition are studied. Sediment after extracting iron and manganese (S-FeMn), which possessed the highest organic carbon (0.99%), had the highest affinity for PFOS under oxic Condition. However, Anoxic environment resulted in an increase of the pH, dissolving of organic carbon and de-protonation of S-FeMn, which caused the lower sorption capacity of PFOS on S-FeMn. Sediment after extracting manganese (S-Mn) had the higher sorption ability in Anoxic environment because the Fe2+ from S-Mn provided more effective electrostatic sites for anionic PFOS. When the environment changed to oxic Condition, the iron existed as trivalent form in S-Mn, which resulted in a block of effective sorption site and reduced the sorption amounts of PFOS. The higher percentage of manganese oxides restrained the sorption of PFOS. Hence, whether or not oxic/Anoxic Condition promoted the PFOS sorption depended on both the percentage and form of various components in the sediment. The study generated further insight into the environmental transport of PFOS in the sediments with different properties and the wetland system, where oxic/Anoxic subsurface flow was constructed.
Yoshinori Kawase - One of the best experts on this subject based on the ideXlab platform.
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Removal of antibiotic sulfamethoxazole by zero-valent iron under oxic and Anoxic Conditions: Removal mechanisms in acidic, neutral and alkaline solutions.
Journal of environmental management, 2017Co-Authors: Maki Kobayashi, Rina Yamaguchi, Shunji Kurosu, Yoshinori KawaseAbstract:Removal of antibiotic sulfamethoxazole (SMX) by zero-valent iron (ZVI) was examined in the range of pH from 3.0 to 11.0 under oxic and Anoxic Conditions to clarify mechanisms of SMX removal in acidic, neutral and alkaline solutions. SMX removal was affected by solution pH and related to the speciation of SMX. Under the oxic Condition, the maximums of SMX removal efficiency and rate were obtained at pH 3.0. The SMX removal efficiency decreased from 100 to 32% with increasing pH in the acidic solutions (3 ≦ pH ≦ 5) and increased to 88% in neutral and moderately alkaline solutions (6 ≦ pH ≦ 10). In highly alkaline solution (pH = 11), the SMX removal was significantly suppressed due to the formation of passive layer on ZVI surface. The removal rate of SMX under the oxic Condition significantly declined with increasing pH. Under the Anoxic Condition, SMX removal was completed within 300 min in the acidic solutions and remained to less than 70% after 300 min in neutral and moderately alkaline solutions. For pH ≧ 10, no SMX removal practically occurred. The removal rate of SMX under the Anoxic Condition approximately remained constant in the acidic solution and largely decreased in neutral and moderately alkaline solutions. SMX removal by ZVI was found to be dominated by the reductive degradation and adsorption under both the oxic and Anoxic Conditions. It was concluded that ZVI has the potential for effective removal of antibiotic SMX under the oxic and Anoxic Conditions. A kinetic model could reasonably simulate the dynamic profiles of SMX removal.
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Removal of cationic dye methylene blue by zero-valent iron: Effects of pH and dissolved oxygen on removal mechanisms.
Journal of environmental science and health. Part A Toxic hazardous substances & environmental engineering, 2015Co-Authors: Xuan Sun, Moe Suzuki, Tomoyo Kurokawa, Minoru Takagi, Yoshinori KawaseAbstract:Effects of pH and dissolved oxygen on mechanisms for decolorization and total organic carbon (TOC) removal of cationic dye methylene blue (MB) by zero-valent iron (ZVI) were systematically examined. Decolorization and TOC removal of MB by ZVI are attributed to the four potential mechanisms, i.e. reduction, degradation, precipitation and adsorption. The contributions of four mechanisms were quantified at pH 3.0, 6.0 and 10.0 in the oxic and Anoxic systems. The maximum efficiencies of decolorization and TOC removal of MB were found at pH 6.0. The TOC removal efficiencies at pH 3.0 and 10.0 were 11.0 and 17.0%, respectively which were considerably lower as compared with 68.1% at pH 6.0. The adsorption, which was favorable at higher pH but was depressed by the passive layer formed on the ZVI surface at alkaline Conditions, characterized the effects of pH on decolorization and TOC removal of MB. The efficiencies of decolorization and TOC removal at pH 6.0 under the Anoxic Condition were 73.0 and 59.0%, respectively, which were comparable to 79.9 and 55.5% obtained under the oxic Condition. In the oxic and Anoxic Conditions, however, the contributions of removal mechanisms were quite different. Although the adsorption dominated the decolorization and TOC removal under the oxic Condition, the contribution of precipitation was largely superior to that of adsorption under the Anoxic Condition.
Jaeweon Cho - One of the best experts on this subject based on the ideXlab platform.
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Effective controls of micropollutants included in wastewater effluent using constructed wetlands under Anoxic Condition
Ecological Engineering, 2009Co-Authors: Noeon Park, Brett J. Vanderford, Shane A. Snyder, Sarper Sarp, Sang Don Kim, Jaeweon ChoAbstract:Abstract An engineered constructed wetland, fed with wastewater effluent, was investigated with respect to the control of organic micropollutants. The levels of 30 different micropollutants, including pharmaceuticals, endocrine disruptors and personal care products, were measured using solid phase extraction, followed by liquid chromatography/tandem mass spectrometer. Only 9 of the 30 chemicals exhibited relatively high concentrations in the effluent samples. Therefore, these were further characterized for their removals by the constructed wetlands. Atenolol, naproxen, and triclosan consistently showed fairly good removal trends, as measured during both May and August 2007. Sulfamethoxazole and dilantine, and carbamazepine, diazepam and triclosan exhibited medium-range and fluctuating (or somewhat low) removal behaviors, respectively. Attempts were made to determine the dominant removal mechanisms, with regard to soils and plants, using two different extraction methods. However, no substantial amounts were detected, thus it was not possible to induce potential removal mechanisms. Analyses of the removal efficiencies and two characteristic parameters (log K ow and p K a ) showed no evidence supporting hydrophobic and electrostatic interactions for the control of micropollutants.
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Organic matter, anion, and metal wastewater treatment in Damyang surface-flow constructed wetlands in Korea
Ecological Engineering, 2008Co-Authors: Noeon Park, Joon Ha Kim, Jaeweon ChoAbstract:Abstract Surface-flow wetlands constructed with Acorus and Typha plants, connected to a wastewater treatment plant, were investigated with respect to organics (dissolved organic matter), anions (nitrate, sulfate, and phosphate), metals (Cu, Ni, Zn, Fe, and Mn), and metalloids (As). The results of the research indicated: (1) effluent organic matter (EfOM), based on dissolved organic carbon (DOC), was not efficiently removed by the wetlands. However, the hydrophobic, transphilic, and hydrophilic EfOM fractions varied throughout the wetlands, as identified by XAD-8/4 resins. (2) Nitrate, as compared to sulfate and phosphate, was efficiently removed, especially in the Typha wetland pond that had long retention time, under Anoxic Condition. (3) Most of the heavy metals were ineffectively removed via the wetland ponds. However, the iron concentration increased in the Typha wetland pond, which was probably due to its reduction under Anoxic Condition.
Qin Zhou - One of the best experts on this subject based on the ideXlab platform.
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influence of oxic Anoxic Condition on sorption behavior of pfos in sediment
Chemosphere, 2016Co-Authors: I A Ololade, Qin ZhouAbstract:Sediment components and redox properties change with oxic/Anoxic Condition, which affect the environmental transport of perfluorooctane sulfonate (PFOS). Herein, the influence of oxic/Anoxic Condition on the variation of redox and residual components of sediments, where organic matter, iron and manganese oxides are separated from the original sediment collected from Lake Taihu, China, are investigated. Meanwhile, the distinguishing sorption behaviors of PFOS on various residual sediments under oxic and Anoxic Condition are studied. Sediment after extracting iron and manganese (S-FeMn), which possessed the highest organic carbon (0.99%), had the highest affinity for PFOS under oxic Condition. However, Anoxic environment resulted in an increase of the pH, dissolving of organic carbon and de-protonation of S-FeMn, which caused the lower sorption capacity of PFOS on S-FeMn. Sediment after extracting manganese (S-Mn) had the higher sorption ability in Anoxic environment because the Fe2+ from S-Mn provided more effective electrostatic sites for anionic PFOS. When the environment changed to oxic Condition, the iron existed as trivalent form in S-Mn, which resulted in a block of effective sorption site and reduced the sorption amounts of PFOS. The higher percentage of manganese oxides restrained the sorption of PFOS. Hence, whether or not oxic/Anoxic Condition promoted the PFOS sorption depended on both the percentage and form of various components in the sediment. The study generated further insight into the environmental transport of PFOS in the sediments with different properties and the wetland system, where oxic/Anoxic subsurface flow was constructed.
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Influence of oxic/Anoxic Condition on sorption behavior of PFOS in sediment.
Chemosphere, 2015Co-Authors: I A Ololade, Qin Zhou, Gang PanAbstract:Sediment components and redox properties change with oxic/Anoxic Condition, which affect the environmental transport of perfluorooctane sulfonate (PFOS). Herein, the influence of oxic/Anoxic Condition on the variation of redox and residual components of sediments, where organic matter, iron and manganese oxides are separated from the original sediment collected from Lake Taihu, China, are investigated. Meanwhile, the distinguishing sorption behaviors of PFOS on various residual sediments under oxic and Anoxic Condition are studied. Sediment after extracting iron and manganese (S-FeMn), which possessed the highest organic carbon (0.99%), had the highest affinity for PFOS under oxic Condition. However, Anoxic environment resulted in an increase of the pH, dissolving of organic carbon and de-protonation of S-FeMn, which caused the lower sorption capacity of PFOS on S-FeMn. Sediment after extracting manganese (S-Mn) had the higher sorption ability in Anoxic environment because the Fe2+ from S-Mn provided more effective electrostatic sites for anionic PFOS. When the environment changed to oxic Condition, the iron existed as trivalent form in S-Mn, which resulted in a block of effective sorption site and reduced the sorption amounts of PFOS. The higher percentage of manganese oxides restrained the sorption of PFOS. Hence, whether or not oxic/Anoxic Condition promoted the PFOS sorption depended on both the percentage and form of various components in the sediment. The study generated further insight into the environmental transport of PFOS in the sediments with different properties and the wetland system, where oxic/Anoxic subsurface flow was constructed.
Timothy W. Davis - One of the best experts on this subject based on the ideXlab platform.
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the secretion of organics by living microcystis under the dark Anoxic Condition and its enhancing effect on nitrate removal
Chemosphere, 2018Co-Authors: Xuechu Chen, Yingying Huang, Guiqin Chen, Yingshi Shen, Timothy W. DavisAbstract:Abstract Recent studies indicated that the algal decomposition produces particulate and dissolved organic carbon (DOC), and can enhance denitrification in eutrophic lakes. However, the effects of the living cyanobacteria on nitrogen cycling in eutrophic lakes were still an unknown question. This study explores a new underlying mechanism of nitrate removal which is driven by living Microcystis . The results suggested that living Microcystis significantly enhanced the nitrate removal at sediment-water interface, with a nitrate removal rate of 0.54 d −1 , which was 2.57 times higher than the nitrate removal rate in the treatment without the addition of Microcystis . Measurements of Chl a and Fv/Fm confirmed that Microcystis was tolerant to the dark/Anoxic Condition, and the recovery experiments suggested that Microcystis could survive under such stress Conditions for at least seven days. Meanwhile, DOC secreted by living Microcystis reached to 4.55 mg C mg −1 Chl a. These secretions were biodegradable hydrophilic and contained carbohydrates and proteins. Our study indicated that during blooms, sinking Microcystis cells could directly provide DOC as carbon source, then consequently enhanced the denitrification at sediment-water interface, and the interactive relationship between living cyanobacteria and permanent nitrate removal should be taken into account while studying nitrogen cycling in aquatic ecosystem.
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The secretion of organics by living Microcystis under the dark/Anoxic Condition and its enhancing effect on nitrate removal.
Chemosphere, 2018Co-Authors: Xuechu Chen, Yingying Huang, Guiqin Chen, Yingshi Shen, Timothy W. DavisAbstract:Abstract Recent studies indicated that the algal decomposition produces particulate and dissolved organic carbon (DOC), and can enhance denitrification in eutrophic lakes. However, the effects of the living cyanobacteria on nitrogen cycling in eutrophic lakes were still an unknown question. This study explores a new underlying mechanism of nitrate removal which is driven by living Microcystis . The results suggested that living Microcystis significantly enhanced the nitrate removal at sediment-water interface, with a nitrate removal rate of 0.54 d −1 , which was 2.57 times higher than the nitrate removal rate in the treatment without the addition of Microcystis . Measurements of Chl a and Fv/Fm confirmed that Microcystis was tolerant to the dark/Anoxic Condition, and the recovery experiments suggested that Microcystis could survive under such stress Conditions for at least seven days. Meanwhile, DOC secreted by living Microcystis reached to 4.55 mg C mg −1 Chl a. These secretions were biodegradable hydrophilic and contained carbohydrates and proteins. Our study indicated that during blooms, sinking Microcystis cells could directly provide DOC as carbon source, then consequently enhanced the denitrification at sediment-water interface, and the interactive relationship between living cyanobacteria and permanent nitrate removal should be taken into account while studying nitrogen cycling in aquatic ecosystem.