Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in ac...Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.展开更多
The practical application of the Feammox for nitrogen removal is challenging in the presence of high amounts of oxygen and organic carbon.This study presents a novel approach to address this issue which involves enhan...The practical application of the Feammox for nitrogen removal is challenging in the presence of high amounts of oxygen and organic carbon.This study presents a novel approach to address this issue which involves enhancing biological nitrogen removal in a magnetic zeolite modified intermittently aerated sequential biological reactor(MZeo-IASBR).The MZeo-IASBR demonstrated excellent performance,achieving 99.09%NH_(4)^(+)-N and 89.12%TN removal efficiencies.The relative abundances of Proteobacteria,Planctomycetota,and Chloroflexi at the phylum level and Delftia and Pirellula at the genus level increased with the addition of NZ@Fe_(3)O_(4),when compared to the microbial community analysis results of the IASBR with no addition of supplements and Zeo-IASBR with the addition of natural zeolite.The genera Acinetobacter and Bdellovibrio were mainly observed in the MZeo-IASBR system,and Acinetobacter may be related to the Feammox process.The combination of NZ@Fe_(3)O_(4)and intermittent aeration under low oxygen levels promoted the aggregation of aerobic denitrifying bacteria and iron-reducing bacteria,which predominately removed nitrogen through the integration of simultaneous nitrification and denitrification(SND),Feammox,anammox,and NDFO processes.The MZeo-IASBR represents a promising strategy for advanced nitrogen removal in wastewater treatment,offering considerable supports for the practical application of Feammox processes.展开更多
基金supported by the National Key R&D Program of China(No.2023YFE0112100)the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Devel-opment Special Fund of Xiamen(No.23YYST064QCB36).
文摘Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.
基金funded by Natural Science Foundation of Fujian Province,China(Nos.2021J011177 and 2022J011231)the 2023 Graduate Science and Technology Innovation Program of Xiamen University of Technology,China(No.YKJCX2023185)the Chunhui Project Foundation of the Education Department of China(No.HZKY20220222).
文摘The practical application of the Feammox for nitrogen removal is challenging in the presence of high amounts of oxygen and organic carbon.This study presents a novel approach to address this issue which involves enhancing biological nitrogen removal in a magnetic zeolite modified intermittently aerated sequential biological reactor(MZeo-IASBR).The MZeo-IASBR demonstrated excellent performance,achieving 99.09%NH_(4)^(+)-N and 89.12%TN removal efficiencies.The relative abundances of Proteobacteria,Planctomycetota,and Chloroflexi at the phylum level and Delftia and Pirellula at the genus level increased with the addition of NZ@Fe_(3)O_(4),when compared to the microbial community analysis results of the IASBR with no addition of supplements and Zeo-IASBR with the addition of natural zeolite.The genera Acinetobacter and Bdellovibrio were mainly observed in the MZeo-IASBR system,and Acinetobacter may be related to the Feammox process.The combination of NZ@Fe_(3)O_(4)and intermittent aeration under low oxygen levels promoted the aggregation of aerobic denitrifying bacteria and iron-reducing bacteria,which predominately removed nitrogen through the integration of simultaneous nitrification and denitrification(SND),Feammox,anammox,and NDFO processes.The MZeo-IASBR represents a promising strategy for advanced nitrogen removal in wastewater treatment,offering considerable supports for the practical application of Feammox processes.
