The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorp...The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.展开更多
In this work,ofloxacin(OFL),a kind of frequently detected antibiotic in groundwater,was selected to explore its impact(at ng/L-μg/L-level)on denitrification performance in an autotrophic denitrification system driven...In this work,ofloxacin(OFL),a kind of frequently detected antibiotic in groundwater,was selected to explore its impact(at ng/L-μg/L-level)on denitrification performance in an autotrophic denitrification system driven by pyrite/sulfur(FeS2/S0).Results showed that OFL restrained nitrate removal efficiency,and the inhibition degree was positively related to the concentration of OFL.After being exposed to increased OFL(200 ng/L-100μg/L)for 69 days,higher inhibition of electron transport activity(ETSA),enzyme activities of nitrate reductase(NAR),and nitrite reductase(NIR)were acquired.Meanwhile,the extracellular protein(PN)content of sludge samples was remarkably stimulated by OFL to resist the augmented toxicity.OFL contributed to increased microbial diversity and sulfur/sulfide oxidation functional genes in ng/L-level bioreactors,whereas led to a decline inμg/L level experiments.With OFL at concentrations of 200 ng/L and 100μg/L,the whole expression of 10 key denitrification functional genes was depressed,and the higher the OFL concentration,the lower the expression level.However,no significant proliferation of antibiotic resistance genes(ARGs)either in 200 ng/L-OFL or 100μg/L-OFL groups was observed.Two-factor correlation analysis results indicated that Thiobacillus,Anaerolineae,Anaerolineales,and Nitrospirae might be the main hosts of existing ARGs in this system.展开更多
Antibiotic contamination has garnered significant attention,particularly given the growing pressures from aquaculture,a key contributor to environmental antibiotic loads.Addressing both antibiotic and nitrogen polluti...Antibiotic contamination has garnered significant attention,particularly given the growing pressures from aquaculture,a key contributor to environmental antibiotic loads.Addressing both antibiotic and nitrogen pollution in such ecosystems is critical.In this study,the aerobic denitrifying bacterium Marinobacter hydrocarbonoclasticus RAD-2,previously isolated in our laboratory,was subjected to a series of concentration gradients(0,20,40,60,80,100 mg/L)to evaluate the single and combined effects of tetracycline(TET)and chlortetracycline(CTC)on the aerobic denitrification process.Among them,the combined effects of antibiotics were set up in a full-factor experimental design(a total of 30 treatment combinations)on the basis of the single-factor experiments of TET and CTC.Results demonstrated that the inhibitory impact of both antibiotics intensified with increasing concentration,with CTC exerting a more pronounced inhibitory effect.Notably,RAD-2 was unable to proliferate at 100 mg/L of TET or 80 mg/L of CTC.High concentrations of either antibiotic significantly suppressed the expression of key denitrification functional genes,including nirX,napA,norB,and nosZ.Furthermore,simultaneous exposure to both antibiotics led to a rapid decline in nitrogen removal efficiency(TET or CTC>60 mg/L),alongside substantial inhibition of bacterial growth and functional gene expression,except for napA.Under specific concentration ranges,the combination of TET and CTC exhibits a certain degree of antagonistic effect.These findings provide critical insights into the restoration of wetland ecosystem health and inform strategies to mitigate the dual challenges of antibiotic and nitrogen pollution in aquaculture effluents.展开更多
In this study,Computational Fluid Dynamics(CFD)together with a component transport model are exploited to investigate the influence of dimensionless parameters,involving the height of the rectifier grid and the instal...In this study,Computational Fluid Dynamics(CFD)together with a component transport model are exploited to investigate the influence of dimensionless parameters,involving the height of the rectifier grid and the installation height of the first catalyst layer,on the flow field and the overall denitration efficiency of a cement kiln’s SCR(Selective catalytic reduction)denitrification reactor.It is shown that accurate numerical results can be obtained by fitting the particle size distribution function to the actual cement kiln fly ash and implementing a non-uniform particle inlet boundary condition.The relative error between denitration efficiency derived from experimental data,numerical simulation,and real-time system pressure drop ranges from 4%to 9%.Optimization of the SCR reactor is achieved when the rectifier grid thickness ratio k/H≥0.030,the rectifier grid height ratio h/H=0.04,and the spacing between the rectifier grid and the first catalyst layer l/H=0.10.Under these conditions,airflow distribution and particle dispersion upstream of the catalyst result in increased denitration efficiencies of 3.21%,3.43%,and 3.27%,respectively,compared to the least favorable operating conditions.展开更多
The contamination of wastewater with organic pollutants and nitrogen compounds poses significant environmental challenges.The primary objective of wastewater treatment is the simultaneous denitrification and decarboni...The contamination of wastewater with organic pollutants and nitrogen compounds poses significant environmental challenges.The primary objective of wastewater treatment is the simultaneous denitrification and decarbonization of ammonia nitrogen and organics into harmless by-products.This study presents a novel method for the directional generation of chlorine radical species like·ClO and·Cl using electro-reactive membranes(EMs)known as RuO_(2)@PbO_(2)-M,which were fabricated using an electro-deposition coupled template approach.This method facilitates the rapid and efficient conversion of ammonia to nitrogen and concurrently reduces the chemical oxygen demand in the effluent.Our system achieved ultra-efficient simultaneous denitrification and decarbonization with minimal energy consumption in single-filtration mode,thereby eliminating the need for chemical precursors.We elucidate the formation pathway of·ClO and·Cl during the electrochemical oxidation process involving RuO_(2)@PbO_(2)-M,where·Cl generated from RuO_(2)reacts with·OH from PbO_(2)under hypochlorous acid conditions,thereby enhancing nitrogen and carbon removal.These findings highlight a novel electro-filtration and an innovative reactive membrane design for·ClO synthesis,which provides a new research framework for the concurrent removal of nitrogen and carbon,and offers a promising solution to enhance wastewater treatment efficiency.展开更多
The transition of the Chinese iron and steel industry to ultralow emissions has accelerated the development of denitrification technologies.Considering the existing dual carbon targets,carbon emissions must be conside...The transition of the Chinese iron and steel industry to ultralow emissions has accelerated the development of denitrification technologies.Considering the existing dual carbon targets,carbon emissions must be considered as a critical indicator when comparing denitrification systems.Consequently,this study provided a comprehensive cost-benefit model for denitrification in the steel industry,encompassing additional carbon emissions resulting from the implementation of denitrification systems.Activated-carbon adsorption and selective catalytic reduction(SCR)systems are two efficient techniques for controlling NOx emissions during sintering.Based on thismodel,a cost-benefit analysis of these two typical systems was conducted,and the results indicated that the unit flue-gas abatement costs of SCR and activated-carbon adsorption systems were 0.00275 and 0.0126 CNY/m^(3),and the unit flue-gas abatement benefits were 0.0072 and 0.0179 CNY/m^(3),respectively.Additionally,the effect of operational characteristics on operating costs,including duration and material prices,was analyzed.When treating the flue gas,the two systems released 0.0020 and 0.0060 kg/m^(3) of carbon dioxide,respectively.The primary sources of carbon emissions from the SCR and activated-carbon adsorption systems are the production of reducing agents and system operations,respectively.Furthermore,considering the features of the activated carbon adsorption system for simultaneous desulfurization,a SCR-wet flue gas desulfurization(WFGD)technology route was developed for comparison with the activated carbon adsorption system.展开更多
Sulfur autotrophic denitrification technology is a low-carbon and environmentally friendly wastewater treatment technology.The effects of factors such as pH,temperature,S/N and salinity on the efficiency of sulfur aut...Sulfur autotrophic denitrification technology is a low-carbon and environmentally friendly wastewater treatment technology.The effects of factors such as pH,temperature,S/N and salinity on the efficiency of sulfur autotrophic denitrification reactions were discussed,and the community characteristics of microorganisms were summarized.This article also introduced the future research and development directions of this process.展开更多
Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubat...Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubation with 15N isotope tracingwas conducted to explore millimeter-scale interactions of N and K on these pathways in soil fertilization zones.After 28 days,individual applications of N and K reduced denitrification-nitrogen removal rate(DNRR),anammox-nitrogen removal rate(ANRR),and feammox-nitrogen removal rate(FNRR)compared to a non-fertilizer control.N fertilizer had a greater effect than K,likely due to the high consumption of dissolved organic carbon by N fertilizer or the increased soil organic matter decomposition by K fertilizer.Combing of N and K increased DNRR,ANRR and FNRR rates by 31%,3090%and 244%compared to single N,and by-53.7%,885%and 222%compared to single K.These effects diminished with depth and distance from fertilizer sites.The effects of N fertilizer on these N removal processes might be regulate abundance of key microbes(e.g.,Limnobacter and Clostridium)and key gene(nirK,hzsB,ACM and Geo)by providing N substrates,while K enhances N metabolism efficiency through enzyme activation,indicated by the downregulation of certain genes(hzsB,ACM and Geo)and a negative correlation with N removal by simultaneously increasing gene expression and enzyme activity.These findings provide insights into how N and K together enhance N removal,emphasizing their importance for optimizing this process.展开更多
Simultaneous nitrification and denitrification(SND)is considered an attractive alternative to traditionally biological nitrogen removal technology.Knowing the effects of heavy metals on the SND process is essential fo...Simultaneous nitrification and denitrification(SND)is considered an attractive alternative to traditionally biological nitrogen removal technology.Knowing the effects of heavy metals on the SND process is essential for engineering.In this study,the responses of SND performance to Zn(Ⅱ)exposure were investigated in a biofilm reactor.The results indicated that Zn(Ⅱ)at low concentration(≤2 mg·L^(-1))had negligible effects on the removal of nitrogen and COD in the SND process compared to that without Zn(Ⅱ),while the removal of ammonium and COD was strongly inhibited with an increasing in the concentration of Zn(Ⅱ)at 5 or 10 mg·L^(-1).Large amounts of extracellular polymeric substance(EPS),especially protein(PN),were secreted to protect microorganisms from the increasing Zn(Ⅱ)damage.High-throughput sequencing analysis indicated that Zn(Ⅱ)exposure could significantly reduce the microbial diversity and change the structure of microbial community.The RDA analysis further confirmed that Azoarcus-Thauera-cluster was the dominant genus in response to low exposure of Zn(Ⅱ)from 1 to 2 mg·L^(-1),while the genus Klebsiella and Enterobacter indicated their adaptability to the presence of elevated Zn(Ⅱ).According to PICRUSt,the abundance of key genes encoding ammonia monooxygenase(EC:1.14.99.39)was obviously reduced after exposure to Zn(Ⅱ),suggesting that the influence of Zn(Ⅱ)on nitrification was greater than that of denitrification,leading to a decrease in ammonium removal of SND system.This study provides a theoretical foundation for understanding the influence of Zn(Ⅱ)on the SND process in a biofilm system,which should be a source of great concern.展开更多
Currently,as environmental pollution becomes increasingly severe,flue gas denitrification has emerged as a significant area of research.With the advancement of modern industry and the improvement of living standards,a...Currently,as environmental pollution becomes increasingly severe,flue gas denitrification has emerged as a significant area of research.With the advancement of modern industry and the improvement of living standards,air pollution has gained growing attention.Sulfur dioxide and nitrogen oxides(NO_(x))have become major contributors to air pollution,posing serious harm to the environment.Consequently,flue gas desulfurization and denitrification technologies have become key research focuses in industrial development.This paper explores the selection of agricultural waste carbon sources and their pretreatment methods.It provides an in-depth analysis of the significance of agricultural waste carbon sources in flue gas denitrification,focusing on their performance and mechanisms.The study also discusses the role of agricultural waste carbon sources in flue gas denitrification,aiming to offer new research perspectives for relevant stakeholders.展开更多
Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two o...Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.展开更多
基金Supported by Basic Scientific Research Project of the Liaoning Provincial Department of Education Has Been Unveiled to Facilitate Local Project Funding (JYTMS20230835)Enhanced Scientific Research Project Funded by the Departmentof Higher Education in Liaoning Province (General program)(JYTMS20230852)。
文摘The adsorptive denitrification performance of MIL-101(Cr)-0.5 toward pyridine,aniline or quinoline in simulated fuels with basic nitrogen content of 1732μg/g was evaluated separately.Furthermore,the effects of adsorption temperature,adsorption time and adsorbent dosage on their adsorptive denitrification performance were systematically investigated.The experimental results demonstrated that under a fixed adsorbent dosage of 0.05 g and a simulated fuel volume of 10 mL,the optimal removal efficiency for aniline was achieved at 30℃ within 30 min,whereas higher temperatures and longer times(40℃and 40 min)were required for effective removal of pyridine and quinoline.Density Functional Theory(DFT)calculations were conducted via Materials Studio(MS)software to study the adsorptive denitrification mechanism of MIL-101(Cr)toward these three basic nitrogen-containing compounds.The simulation calculation results revealed that the interaction between pyridine and MIL-101(Cr)primarily involved coordination adsorption.In contrast,the interaction between aniline or quinoline and MIL-101(Cr)proceeded mainly through coordination,with additional contributions fromπ-complexation and hydrogen bonding.The overall adsorption strength order is pyridine>aniline>quinoline.During the adsorption process,pyridine and quinoline transfer electrons to the MIL-101(Cr)surface through the H→C→N→Cr^(3+)pathway,while aniline transfers electrons to the MIL-101(Cr)surface through various pathways,including N→Cr^(3+),N→C→Cr^(3+)and N→H→O.Furthermore,adsorption kinetics studies indicated that the adsorption processes for all three basic nitrogen-containing compounds followed the quasi second order kinetic models.The experimental results on the effect of benzene on the adsorptive denitrification performance of MIL-101(Cr)-0.5 demonstrated that benzene exerted a more significant impact on the adsorption of aniline and quinoline.Finally,the adsorbent was regenerated using ethanol washing.It was found that MIL-101(Cr)-0.5 retained stable denitrification performance after two regeneration cycles.
基金supported by the National Natural Science Foundation of China(No.42377083)the Natural Science Foundation of Sichuan Province,China(No.2025 ZNSFSC0433).
文摘In this work,ofloxacin(OFL),a kind of frequently detected antibiotic in groundwater,was selected to explore its impact(at ng/L-μg/L-level)on denitrification performance in an autotrophic denitrification system driven by pyrite/sulfur(FeS2/S0).Results showed that OFL restrained nitrate removal efficiency,and the inhibition degree was positively related to the concentration of OFL.After being exposed to increased OFL(200 ng/L-100μg/L)for 69 days,higher inhibition of electron transport activity(ETSA),enzyme activities of nitrate reductase(NAR),and nitrite reductase(NIR)were acquired.Meanwhile,the extracellular protein(PN)content of sludge samples was remarkably stimulated by OFL to resist the augmented toxicity.OFL contributed to increased microbial diversity and sulfur/sulfide oxidation functional genes in ng/L-level bioreactors,whereas led to a decline inμg/L level experiments.With OFL at concentrations of 200 ng/L and 100μg/L,the whole expression of 10 key denitrification functional genes was depressed,and the higher the OFL concentration,the lower the expression level.However,no significant proliferation of antibiotic resistance genes(ARGs)either in 200 ng/L-OFL or 100μg/L-OFL groups was observed.Two-factor correlation analysis results indicated that Thiobacillus,Anaerolineae,Anaerolineales,and Nitrospirae might be the main hosts of existing ARGs in this system.
基金supported by the Science Fund for Distinguished Young Scholars of Zhejiang Province(No.LR22C190001)the National Natural Science Foundation of China(No.41401556).
文摘Antibiotic contamination has garnered significant attention,particularly given the growing pressures from aquaculture,a key contributor to environmental antibiotic loads.Addressing both antibiotic and nitrogen pollution in such ecosystems is critical.In this study,the aerobic denitrifying bacterium Marinobacter hydrocarbonoclasticus RAD-2,previously isolated in our laboratory,was subjected to a series of concentration gradients(0,20,40,60,80,100 mg/L)to evaluate the single and combined effects of tetracycline(TET)and chlortetracycline(CTC)on the aerobic denitrification process.Among them,the combined effects of antibiotics were set up in a full-factor experimental design(a total of 30 treatment combinations)on the basis of the single-factor experiments of TET and CTC.Results demonstrated that the inhibitory impact of both antibiotics intensified with increasing concentration,with CTC exerting a more pronounced inhibitory effect.Notably,RAD-2 was unable to proliferate at 100 mg/L of TET or 80 mg/L of CTC.High concentrations of either antibiotic significantly suppressed the expression of key denitrification functional genes,including nirX,napA,norB,and nosZ.Furthermore,simultaneous exposure to both antibiotics led to a rapid decline in nitrogen removal efficiency(TET or CTC>60 mg/L),alongside substantial inhibition of bacterial growth and functional gene expression,except for napA.Under specific concentration ranges,the combination of TET and CTC exhibits a certain degree of antagonistic effect.These findings provide critical insights into the restoration of wetland ecosystem health and inform strategies to mitigate the dual challenges of antibiotic and nitrogen pollution in aquaculture effluents.
基金Anhui Province Key Research and Development Plan of the Ecological Environment Project(No.202104i07020016).
文摘In this study,Computational Fluid Dynamics(CFD)together with a component transport model are exploited to investigate the influence of dimensionless parameters,involving the height of the rectifier grid and the installation height of the first catalyst layer,on the flow field and the overall denitration efficiency of a cement kiln’s SCR(Selective catalytic reduction)denitrification reactor.It is shown that accurate numerical results can be obtained by fitting the particle size distribution function to the actual cement kiln fly ash and implementing a non-uniform particle inlet boundary condition.The relative error between denitration efficiency derived from experimental data,numerical simulation,and real-time system pressure drop ranges from 4%to 9%.Optimization of the SCR reactor is achieved when the rectifier grid thickness ratio k/H≥0.030,the rectifier grid height ratio h/H=0.04,and the spacing between the rectifier grid and the first catalyst layer l/H=0.10.Under these conditions,airflow distribution and particle dispersion upstream of the catalyst result in increased denitration efficiencies of 3.21%,3.43%,and 3.27%,respectively,compared to the least favorable operating conditions.
基金supported by the National Natural Science Foundation of China(52270043)the National Key Research and Development Program of China(2023YFE0113800 and 2024YFC3715000)the Natural Science Foundation of Beijing Municipality(8242030).
文摘The contamination of wastewater with organic pollutants and nitrogen compounds poses significant environmental challenges.The primary objective of wastewater treatment is the simultaneous denitrification and decarbonization of ammonia nitrogen and organics into harmless by-products.This study presents a novel method for the directional generation of chlorine radical species like·ClO and·Cl using electro-reactive membranes(EMs)known as RuO_(2)@PbO_(2)-M,which were fabricated using an electro-deposition coupled template approach.This method facilitates the rapid and efficient conversion of ammonia to nitrogen and concurrently reduces the chemical oxygen demand in the effluent.Our system achieved ultra-efficient simultaneous denitrification and decarbonization with minimal energy consumption in single-filtration mode,thereby eliminating the need for chemical precursors.We elucidate the formation pathway of·ClO and·Cl during the electrochemical oxidation process involving RuO_(2)@PbO_(2)-M,where·Cl generated from RuO_(2)reacts with·OH from PbO_(2)under hypochlorous acid conditions,thereby enhancing nitrogen and carbon removal.These findings highlight a novel electro-filtration and an innovative reactive membrane design for·ClO synthesis,which provides a new research framework for the concurrent removal of nitrogen and carbon,and offers a promising solution to enhance wastewater treatment efficiency.
基金supported by the National Key Research and Development Program of China(No.2022YFC3703403)Zhejiang Provincial“LeadWild Goose”Research and Development Project(No.2022C03073).
文摘The transition of the Chinese iron and steel industry to ultralow emissions has accelerated the development of denitrification technologies.Considering the existing dual carbon targets,carbon emissions must be considered as a critical indicator when comparing denitrification systems.Consequently,this study provided a comprehensive cost-benefit model for denitrification in the steel industry,encompassing additional carbon emissions resulting from the implementation of denitrification systems.Activated-carbon adsorption and selective catalytic reduction(SCR)systems are two efficient techniques for controlling NOx emissions during sintering.Based on thismodel,a cost-benefit analysis of these two typical systems was conducted,and the results indicated that the unit flue-gas abatement costs of SCR and activated-carbon adsorption systems were 0.00275 and 0.0126 CNY/m^(3),and the unit flue-gas abatement benefits were 0.0072 and 0.0179 CNY/m^(3),respectively.Additionally,the effect of operational characteristics on operating costs,including duration and material prices,was analyzed.When treating the flue gas,the two systems released 0.0020 and 0.0060 kg/m^(3) of carbon dioxide,respectively.The primary sources of carbon emissions from the SCR and activated-carbon adsorption systems are the production of reducing agents and system operations,respectively.Furthermore,considering the features of the activated carbon adsorption system for simultaneous desulfurization,a SCR-wet flue gas desulfurization(WFGD)technology route was developed for comparison with the activated carbon adsorption system.
文摘Sulfur autotrophic denitrification technology is a low-carbon and environmentally friendly wastewater treatment technology.The effects of factors such as pH,temperature,S/N and salinity on the efficiency of sulfur autotrophic denitrification reactions were discussed,and the community characteristics of microorganisms were summarized.This article also introduced the future research and development directions of this process.
基金supported by the National Natural Science Foundation of China(Nos.32271726 and 32171648)the Natural Science Foundation of Hubei Province of China(No.2022CFB030)。
文摘Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubation with 15N isotope tracingwas conducted to explore millimeter-scale interactions of N and K on these pathways in soil fertilization zones.After 28 days,individual applications of N and K reduced denitrification-nitrogen removal rate(DNRR),anammox-nitrogen removal rate(ANRR),and feammox-nitrogen removal rate(FNRR)compared to a non-fertilizer control.N fertilizer had a greater effect than K,likely due to the high consumption of dissolved organic carbon by N fertilizer or the increased soil organic matter decomposition by K fertilizer.Combing of N and K increased DNRR,ANRR and FNRR rates by 31%,3090%and 244%compared to single N,and by-53.7%,885%and 222%compared to single K.These effects diminished with depth and distance from fertilizer sites.The effects of N fertilizer on these N removal processes might be regulate abundance of key microbes(e.g.,Limnobacter and Clostridium)and key gene(nirK,hzsB,ACM and Geo)by providing N substrates,while K enhances N metabolism efficiency through enzyme activation,indicated by the downregulation of certain genes(hzsB,ACM and Geo)and a negative correlation with N removal by simultaneously increasing gene expression and enzyme activity.These findings provide insights into how N and K together enhance N removal,emphasizing their importance for optimizing this process.
基金supported by the Shanxi Province Science Foundation for Youths(20210302124348 and 202103021223099)the Basic Research Project for the ShanxiZheda Institute of Advanced Materials and Chemical Engineering(2021SX-AT004)the National Natural Science Foundation of China(51778397).
文摘Simultaneous nitrification and denitrification(SND)is considered an attractive alternative to traditionally biological nitrogen removal technology.Knowing the effects of heavy metals on the SND process is essential for engineering.In this study,the responses of SND performance to Zn(Ⅱ)exposure were investigated in a biofilm reactor.The results indicated that Zn(Ⅱ)at low concentration(≤2 mg·L^(-1))had negligible effects on the removal of nitrogen and COD in the SND process compared to that without Zn(Ⅱ),while the removal of ammonium and COD was strongly inhibited with an increasing in the concentration of Zn(Ⅱ)at 5 or 10 mg·L^(-1).Large amounts of extracellular polymeric substance(EPS),especially protein(PN),were secreted to protect microorganisms from the increasing Zn(Ⅱ)damage.High-throughput sequencing analysis indicated that Zn(Ⅱ)exposure could significantly reduce the microbial diversity and change the structure of microbial community.The RDA analysis further confirmed that Azoarcus-Thauera-cluster was the dominant genus in response to low exposure of Zn(Ⅱ)from 1 to 2 mg·L^(-1),while the genus Klebsiella and Enterobacter indicated their adaptability to the presence of elevated Zn(Ⅱ).According to PICRUSt,the abundance of key genes encoding ammonia monooxygenase(EC:1.14.99.39)was obviously reduced after exposure to Zn(Ⅱ),suggesting that the influence of Zn(Ⅱ)on nitrification was greater than that of denitrification,leading to a decrease in ammonium removal of SND system.This study provides a theoretical foundation for understanding the influence of Zn(Ⅱ)on the SND process in a biofilm system,which should be a source of great concern.
文摘Currently,as environmental pollution becomes increasingly severe,flue gas denitrification has emerged as a significant area of research.With the advancement of modern industry and the improvement of living standards,air pollution has gained growing attention.Sulfur dioxide and nitrogen oxides(NO_(x))have become major contributors to air pollution,posing serious harm to the environment.Consequently,flue gas desulfurization and denitrification technologies have become key research focuses in industrial development.This paper explores the selection of agricultural waste carbon sources and their pretreatment methods.It provides an in-depth analysis of the significance of agricultural waste carbon sources in flue gas denitrification,focusing on their performance and mechanisms.The study also discusses the role of agricultural waste carbon sources in flue gas denitrification,aiming to offer new research perspectives for relevant stakeholders.
文摘Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.
