This study investigates the simultaneous accumulation of S^(0) and NO_(2)^(-)during short-cut sulfur autotrophic denitrification(SSADN)in response to 0-35 mg/L hydroxylamine(NH_(2)OH)addition.At a dosage of 15 mg/L NH...This study investigates the simultaneous accumulation of S^(0) and NO_(2)^(-)during short-cut sulfur autotrophic denitrification(SSADN)in response to 0-35 mg/L hydroxylamine(NH_(2)OH)addition.At a dosage of 15 mg/L NH_(2)OH,the accumulation of NO_(2)^(-)-N peaked at 32.49±1.33 mg/L,which is 1.65 times higher than that of the control.The addition of NH_(2)OH facilitates the retention of S^(0) in the system.Enzyme assays indicated significant discrepancies in the enhanced NO_(2)^(-)-N reductase(NAR)and NO_(2)^(-)-N reductase(NIR)activities induced by NH_(2)OH are responsible for the excellent NO_(2)^(-)-N production.These results are supported by the corresponding NO_(3)^(-)-N reduction genes(napA,narG)and NO_(2)^(-)-N reduction genes(nirS,nirK).In addition,the abundance of sulfur oxidation genes(soxB)decreases with increasing NH_(2)OH dosage,inhibiting further oxidation of S^(0) to SO_(4)^(2-).The accumulation of NO_(2)^(-)-N and S^(0) increases from 45.8% and 36.8% to 70.04% and 52.52%,respectively,with the addition of 2 mg/L NH_(2)OH in the continuous-flow up-flow anaerobic sludge blanket(UASB)reactor.展开更多
The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using ...The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.展开更多
A new wastewater treatment facility—lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has ...A new wastewater treatment facility—lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has the function of nitrification and removing organic substrate. In this study, we focused on the denitrification performance of LBAF and its possible mechanism under thorough aeration. We identified the existence of simultaneous nitrification and denitrification (SND) by analyzing nitrogenous compounds along the flow path of LBAF and supportive microbial microscopy, and studied the effects of air/water ratio and hydraulic loading on the performance of nitrogen removal and on SND in LBAF to find out the optimal operation condition. It is found that for saving operation cost, aeration can be reduced to some degree that allows desirable removal efficiency of pollutants, and the optimal air/water ratio is 10:1. Hydraulic loading less than 0.43 m h?1 hardly affects the nitrification and denitrification performance; whereas higher hydraulic loading is unfavorable to both nitrification and denitrification, far more unfavorable to denitrification than to nitrification.展开更多
The contributions of nitrification and denitrification to N2O and N2 emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0...The contributions of nitrification and denitrification to N2O and N2 emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C2H2 were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N2O>nitrification N2O>Denitrification N2. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N2O>Denitrification N2.展开更多
A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrific...A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2 mg/L, and total phosphorus of 0.3 mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrifieation.展开更多
基金supported by the Shandong Provincial Natural Science Foundation(No.ZR2019MEE038,ZR202110260011)the Scientific research project of Xinjiang oilfield company(No.2022C4004)the Qingdao West-Coast Economic New Area Scientific and Technological Project of the special open competition mechanism to select the best candidates(2022-14).
文摘This study investigates the simultaneous accumulation of S^(0) and NO_(2)^(-)during short-cut sulfur autotrophic denitrification(SSADN)in response to 0-35 mg/L hydroxylamine(NH_(2)OH)addition.At a dosage of 15 mg/L NH_(2)OH,the accumulation of NO_(2)^(-)-N peaked at 32.49±1.33 mg/L,which is 1.65 times higher than that of the control.The addition of NH_(2)OH facilitates the retention of S^(0) in the system.Enzyme assays indicated significant discrepancies in the enhanced NO_(2)^(-)-N reductase(NAR)and NO_(2)^(-)-N reductase(NIR)activities induced by NH_(2)OH are responsible for the excellent NO_(2)^(-)-N production.These results are supported by the corresponding NO_(3)^(-)-N reduction genes(napA,narG)and NO_(2)^(-)-N reduction genes(nirS,nirK).In addition,the abundance of sulfur oxidation genes(soxB)decreases with increasing NH_(2)OH dosage,inhibiting further oxidation of S^(0) to SO_(4)^(2-).The accumulation of NO_(2)^(-)-N and S^(0) increases from 45.8% and 36.8% to 70.04% and 52.52%,respectively,with the addition of 2 mg/L NH_(2)OH in the continuous-flow up-flow anaerobic sludge blanket(UASB)reactor.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China(No.51574214).
文摘The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.
基金Funded by the National Key Technologies R & D Program of China During the 10th Five-Year Plan Periods of China (No.2001BA604A01-03).
文摘A new wastewater treatment facility—lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has the function of nitrification and removing organic substrate. In this study, we focused on the denitrification performance of LBAF and its possible mechanism under thorough aeration. We identified the existence of simultaneous nitrification and denitrification (SND) by analyzing nitrogenous compounds along the flow path of LBAF and supportive microbial microscopy, and studied the effects of air/water ratio and hydraulic loading on the performance of nitrogen removal and on SND in LBAF to find out the optimal operation condition. It is found that for saving operation cost, aeration can be reduced to some degree that allows desirable removal efficiency of pollutants, and the optimal air/water ratio is 10:1. Hydraulic loading less than 0.43 m h?1 hardly affects the nitrification and denitrification performance; whereas higher hydraulic loading is unfavorable to both nitrification and denitrification, far more unfavorable to denitrification than to nitrification.
基金he National Natural Science Foundation of China!(No.49701016)the Hundred Scientists" Project of Chinese Academy of Sciences
文摘The contributions of nitrification and denitrification to N2O and N2 emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C2H2 were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N2O>nitrification N2O>Denitrification N2. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N2O>Denitrification N2.
基金Sponsored by the National Natural Science Foundation of China(5052114007550478084)
文摘A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2 mg/L, and total phosphorus of 0.3 mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrifieation.
