Electrochemical oxidation of ammonia was studied with an objective to enhance the selectivity of ammonia to nitrogen gas and to remove the by-products in an undivided electrochemical cell, in which various cathodes an...Electrochemical oxidation of ammonia was studied with an objective to enhance the selectivity of ammonia to nitrogen gas and to remove the by-products in an undivided electrochemical cell, in which various cathodes and Ti/RuO 2-Pt anode were assembled. In the present study, anodic oxidation of ammonia and cathodic reduction of by-products were achieved, especially with Cu/Zn as cathode. In the presence of 1.0 g/L NaCl the ammonia-N decreased from 100.0 to 0 after 120 min electrolysis at current density of 30 mA/cm2, and no nitrite was detected in the treated solution. The lowest amount of nitrate was formed with Cu/Zn as cathode during electrolysis due to its high reduction ability. Initial pH range from 7 and 9 and uncontrolled temperature were favorable for electrochemical ammonia oxidation and the ammonia oxidation rates with Cu/Zn cathode was higher than that with Ti and Fe cathode. The reduction rate increased with increasing current density in the range of 5 - 50 mA/cm2. As ammonia could be completely removed by the simultaneous oxidation and reduction in this study, it is suitable for deep treatment of ammonia polluted water.展开更多
Anaerobic digestion(AD)of waste activated sludge(WAS)is usually limited by the low generation efficiency of methane.Fe(Ⅲ)-loaded chitosan composite(CTS-Fe)have been reported to effectively enhanced the digestion of W...Anaerobic digestion(AD)of waste activated sludge(WAS)is usually limited by the low generation efficiency of methane.Fe(Ⅲ)-loaded chitosan composite(CTS-Fe)have been reported to effectively enhanced the digestion of WAS,but its role in promoting anaerobic sludge digestion remains unclear.In present study,the effects of CTS-Fe on the hydrolysis and methanogenesis stages of WAS anaerobic digestion were investigated.The addition of CTSFe increased methane production potential by 8%-23%under the tested conditions with the addition of 5-20 g/L CTS-Fe.Besides,the results demonstrate that the addition of CTS-Fe could effectively promote the hydrolysis of WAS,evidenced by lower protein or polysaccharides concentration,higher soluble organic carbon in rector adding CTS-Fe,as well as the increased activity of extracellular hydrolase with higher CTS-Fe concentration.Meanwhile,the enrichment of Clostridia abundance(iron-reducing bacteria(IRBs))was observed in CTS-Fe adding reactor(8.9%-13.8%),which was higher than that in the control reactor(7.9%).The observation further suggesting the acceleration of hydrolysis through dissimilatory iron reduction(DIR)process,thus providing abundant substrates for methanogenesis.However,the presence of CTS-Fe was inhibited the acetoclastic and hydrogenotrophic methanogenesis process,which could be ascribed to the Fe(Ⅲ)act as electron acceptor coupled to methane for anaerobic oxidation.Furthermore,coenzyme F420 activity in the CTS-Fe added reactor was 34.9% lower than in the blank,also abundance of microorganisms involved in hydrogenotrophic methanogenesis was decreased.Results from this study could provide theoretical support for the practical applications of CTS-Fe.展开更多
A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rate...A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand（COD）volumetric loadings,solid retention times（SRT）and ratios of COD to total nitrogen（TN）or COD/TN.Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics.Mass balance analysis revealed that greater than 60%of antibiotics in the influent were biodegraded in the IASBR,whereas averagely 24%were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium.Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand（COD）volumetric loadings,which could achieve up to 85.1%±1.4%at 0.17±0.041 kg COD/m-3/day,while dropped to 75.9%±1.3%and 49.3%±12.1%when COD volumetric loading increased to 0.65±0.032 and1.07±0.073 kg COD/m-3/day,respectively.Tetracyclines,the dominant antibiotics in ADSW,were removed by 87.9%in total at the lowest COD loading,of which 30.4%were contributed by sludge sorption and 57.5%by biodegradation,respectively.In contrast,sulfonamides were removed about 96.2%,almost by biodegradation.Long SRT seemed to have little obvious impact on antibiotics removal,while a shorter SRT of 30–40 day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge.Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work.展开更多
Ammonia has emerged as a promising hydrogen carrier with applications as an energy source in recent years. However, in addition to being toxic, gaseous ammonia is a precursor of secondary inorganic aerosols. The conce...Ammonia has emerged as a promising hydrogen carrier with applications as an energy source in recent years. However, in addition to being toxic, gaseous ammonia is a precursor of secondary inorganic aerosols. The concentration of ambient fine particulate matter （PM2.5） is intrinsically connected to public health. In this study, PM2.5-related health impacts of utilizing ammonia-hydrogen energy in Kanto Region, Japan, were investigated. It was assumed that 20% of the electricity consumption in Kanto Region, the most populated area in Japan, was supplied by mnmonia-hydrogen energy. The PM2.5 resulted from incomplete ammonia decomposition was simulated by a chemical transport model： ADMER-PRO （modified version）. Based on the incremental PM2.5 concentration, health impacts on the elderly （individuals over 65 years old） were quantitatively evaluated. The ammonia emission in this scenario increased PM2 s by 11.7% （0.16 μg·m-3.y-1） in winter and 3.5% （0.08 μg · m-3.y-1） in summer, resulting in 351 premature deaths per year. This study suggests that cost- effective emissions control or treatment and appropriate land planning should be considered to reduce the associated health impacts of this type of energy generation. In addition, further in-depth research, including cost-benefit analysis and security standards, is needed.展开更多
文摘Electrochemical oxidation of ammonia was studied with an objective to enhance the selectivity of ammonia to nitrogen gas and to remove the by-products in an undivided electrochemical cell, in which various cathodes and Ti/RuO 2-Pt anode were assembled. In the present study, anodic oxidation of ammonia and cathodic reduction of by-products were achieved, especially with Cu/Zn as cathode. In the presence of 1.0 g/L NaCl the ammonia-N decreased from 100.0 to 0 after 120 min electrolysis at current density of 30 mA/cm2, and no nitrite was detected in the treated solution. The lowest amount of nitrate was formed with Cu/Zn as cathode during electrolysis due to its high reduction ability. Initial pH range from 7 and 9 and uncontrolled temperature were favorable for electrochemical ammonia oxidation and the ammonia oxidation rates with Cu/Zn cathode was higher than that with Ti and Fe cathode. The reduction rate increased with increasing current density in the range of 5 - 50 mA/cm2. As ammonia could be completely removed by the simultaneous oxidation and reduction in this study, it is suitable for deep treatment of ammonia polluted water.
基金supported by the National Natural Science Foundation of China(No.52200031)。
文摘Anaerobic digestion(AD)of waste activated sludge(WAS)is usually limited by the low generation efficiency of methane.Fe(Ⅲ)-loaded chitosan composite(CTS-Fe)have been reported to effectively enhanced the digestion of WAS,but its role in promoting anaerobic sludge digestion remains unclear.In present study,the effects of CTS-Fe on the hydrolysis and methanogenesis stages of WAS anaerobic digestion were investigated.The addition of CTSFe increased methane production potential by 8%-23%under the tested conditions with the addition of 5-20 g/L CTS-Fe.Besides,the results demonstrate that the addition of CTS-Fe could effectively promote the hydrolysis of WAS,evidenced by lower protein or polysaccharides concentration,higher soluble organic carbon in rector adding CTS-Fe,as well as the increased activity of extracellular hydrolase with higher CTS-Fe concentration.Meanwhile,the enrichment of Clostridia abundance(iron-reducing bacteria(IRBs))was observed in CTS-Fe adding reactor(8.9%-13.8%),which was higher than that in the control reactor(7.9%).The observation further suggesting the acceleration of hydrolysis through dissimilatory iron reduction(DIR)process,thus providing abundant substrates for methanogenesis.However,the presence of CTS-Fe was inhibited the acetoclastic and hydrogenotrophic methanogenesis process,which could be ascribed to the Fe(Ⅲ)act as electron acceptor coupled to methane for anaerobic oxidation.Furthermore,coenzyme F420 activity in the CTS-Fe added reactor was 34.9% lower than in the blank,also abundance of microorganisms involved in hydrogenotrophic methanogenesis was decreased.Results from this study could provide theoretical support for the practical applications of CTS-Fe.
文摘A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand（COD）volumetric loadings,solid retention times（SRT）and ratios of COD to total nitrogen（TN）or COD/TN.Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics.Mass balance analysis revealed that greater than 60%of antibiotics in the influent were biodegraded in the IASBR,whereas averagely 24%were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium.Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand（COD）volumetric loadings,which could achieve up to 85.1%±1.4%at 0.17±0.041 kg COD/m-3/day,while dropped to 75.9%±1.3%and 49.3%±12.1%when COD volumetric loading increased to 0.65±0.032 and1.07±0.073 kg COD/m-3/day,respectively.Tetracyclines,the dominant antibiotics in ADSW,were removed by 87.9%in total at the lowest COD loading,of which 30.4%were contributed by sludge sorption and 57.5%by biodegradation,respectively.In contrast,sulfonamides were removed about 96.2%,almost by biodegradation.Long SRT seemed to have little obvious impact on antibiotics removal,while a shorter SRT of 30–40 day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge.Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work.
文摘Ammonia has emerged as a promising hydrogen carrier with applications as an energy source in recent years. However, in addition to being toxic, gaseous ammonia is a precursor of secondary inorganic aerosols. The concentration of ambient fine particulate matter （PM2.5） is intrinsically connected to public health. In this study, PM2.5-related health impacts of utilizing ammonia-hydrogen energy in Kanto Region, Japan, were investigated. It was assumed that 20% of the electricity consumption in Kanto Region, the most populated area in Japan, was supplied by mnmonia-hydrogen energy. The PM2.5 resulted from incomplete ammonia decomposition was simulated by a chemical transport model： ADMER-PRO （modified version）. Based on the incremental PM2.5 concentration, health impacts on the elderly （individuals over 65 years old） were quantitatively evaluated. The ammonia emission in this scenario increased PM2 s by 11.7% （0.16 μg·m-3.y-1） in winter and 3.5% （0.08 μg · m-3.y-1） in summer, resulting in 351 premature deaths per year. This study suggests that cost- effective emissions control or treatment and appropriate land planning should be considered to reduce the associated health impacts of this type of energy generation. In addition, further in-depth research, including cost-benefit analysis and security standards, is needed.
