This study employed multispectral techniques to evaluate fulvic acid(FA)compositional characteristic and elucidate its biodegradation mechanisms during partial nitritation(PN)process.Results showed that FA removal eff...This study employed multispectral techniques to evaluate fulvic acid(FA)compositional characteristic and elucidate its biodegradation mechanisms during partial nitritation(PN)process.Results showed that FA removal efficiency(FRE)decreased from 90.22 to 23.11%when FA concentrations in the reactor were increased from 0 to 162.30 mg/L,and that molecular size,degree of aromatization and humification of the effluent FA macromolecules all increased after treatment.Microbial population analysis indicated that the proliferation of the Comamonas,OLB12 and Thauera exhibit high FA utilization capacity in lower concentrations(<50.59 mg/L),promoting the degradation and removal of macromolecular FA.In addition,the sustained increase in external FA may decrease the abundance of above functional microorganisms,resulting in a rapid drop in FRE.Furthermore,from the genetic perspective,the elevated FA levels restricted carbohydrate(ko00620,ko00010 and ko00020)and nitrogen(HAO,AMO,NIR and NOR)metabolism-related pathways,thereby impeding FA removal and total nitrogen loss associated with N_(2)O emissions.展开更多
Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^...Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.展开更多
The long-term impact of fulvic acid(FA)on partial nitritation(PN)systemwas initially examined in this study.The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulatio...The long-term impact of fulvic acid(FA)on partial nitritation(PN)systemwas initially examined in this study.The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulation rate(NAR nearly 100%)and ammonium removal rate(ARR 56.85%),while FA over 50 mg/L decreased ARR from 56.85%to 0.7%.Sludge characteristics analysis found that appropriate FA(<50 mg/L)exposure promoted the settling performance and granulation of PN sludge by removing Bacteroidetes and accumulating Chloroflexi.The analysis of metagenomics suggested that the presence of limited FA(0-50 mg/L)stimulated the generation of NADH,which favors the denitrification and nitrite reduction.The negative impact of FA on the PN system could be divided into two stages.Initially,limited FA(50-120 mg/L)was decomposed by Anaerolineae to stimulate the growth and propagation of heterotrophic bacteria(Thauera).Increasing heterotrophs competed with AOB(Nitrosomonas)for dissolved oxygen,causing AOB to be eliminated and ARR to declined.Subsequently,when FA dosage was over 120 mg/L,Anaerolineae were inhibited and heterotrophic bacteria reduced,resulting in the abundance of AOB recovered.Nevertheless,the ammonium transformation pathway was suppressed because genes amoABC and hao were obviously reduced,leading to the deterioration of reactor performance.Overall,these results provide theoretical guidance for the practical application of PN for the treatment of FA-containing sewage.展开更多
A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composi...A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composition,evolution,and interactions.The stable operation phase(31-300 d)began after a 30 days of start-up period,reaching an average nitrite accumulation ratio(NAR)of 94.43%and a ratio of nitrite nitrogen to ammonia nitrogen(NO_(2)^(−)-N/NH_(4)^(+)-N)of 1.16.Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks,which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank,and organic matter degrading bacteria in the anoxic tank.The ammonia-oxidizing bacteria(AOB)Nitrosomonas was found to be the key functional bacteria,exhibiting an increase in abundance from 0.27%to 6.38%,due to its collaborative interactions with organic matter degrading bacteria.In-situ inhibition of nitrite-oxidizing bacteria(NOB)was achieved using a combination of free ammonia(FA)and free nitrous acid(FNA),low dissolved oxygen(DO)with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO_(2)^(−)-N/NH_(4)^(+)-N,without an adverse impact on AOB.The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria,were found to contribute to the enhanced PN performance and microbial community structure stability.These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.展开更多
We investigated the effects of Leuconostoc mesenteroides subsp.IMAU:80679 and ascorbic acid on colour development and lipid oxidation as well as protein oxidation of fermented sausages during processing.Four different...We investigated the effects of Leuconostoc mesenteroides subsp.IMAU:80679 and ascorbic acid on colour development and lipid oxidation as well as protein oxidation of fermented sausages during processing.Four different groups of sausage batters were prepared for the experiment,including Nitrite group,ascorbic acid group(Aa),Leuconostoc mesenteroides subsp.group(LMS)and LMS+Aa group.The analysis of total viable count(TVC)and lactic acid bacteria(LAB)counts showed the starter culture adapted well and became the predominant population during fermentation.The redness of the LMS+Aa sausages reached 11.42±0.91,lower than 50 ppm nitrite added sausages of 13.00±1.41 but significantly higher than their individual addition(p<0.05).After ripening,the relative content of DeoMb and OxyMb in LMS+Aa sample was 56.46±1.35%,lower than Aa group of 62.01±3.38%,but higher than LMS group of 39.54±3.37%and Nitrite group of 24.06±3.34(p<0.05).The highest TVB-N,TBARS,carbonyls content and the lowest sulfhydryl content were observed in the Nitrite sausages,and these values except sulfhydryl content in the sausages treated with L.mesenteroides subsp.were higher than in that treated with both inoculation and ascorbic acid.The photochemical information from UV-vis fluorescent analysis revealed that the existing status of Nitrosylmyoglobin(NO-Mb)and Zinc protoporphyrin IX(Znpp)in inoculated sausages.The combination of L.mesenteroides subsp.and ascorbic acid resulted in the highest intensity of NOMb and the highest content of Znpp among all sausages.Therefore,these results showed that ascorbic acid combined with L.mesenteroides subsp.is able to enhance the oxidation-reduction and colour improvement and could be a potential alternative to substitute nitrite in fermented sausages.展开更多
基金supported by the Key Research and Development Project of Shandong (Nos.2021CXGC011202,2020CXGC011404,and 2022CXGC021002)the National Natural Science Foundation of China (No.22276006)。
文摘This study employed multispectral techniques to evaluate fulvic acid(FA)compositional characteristic and elucidate its biodegradation mechanisms during partial nitritation(PN)process.Results showed that FA removal efficiency(FRE)decreased from 90.22 to 23.11%when FA concentrations in the reactor were increased from 0 to 162.30 mg/L,and that molecular size,degree of aromatization and humification of the effluent FA macromolecules all increased after treatment.Microbial population analysis indicated that the proliferation of the Comamonas,OLB12 and Thauera exhibit high FA utilization capacity in lower concentrations(<50.59 mg/L),promoting the degradation and removal of macromolecular FA.In addition,the sustained increase in external FA may decrease the abundance of above functional microorganisms,resulting in a rapid drop in FRE.Furthermore,from the genetic perspective,the elevated FA levels restricted carbohydrate(ko00620,ko00010 and ko00020)and nitrogen(HAO,AMO,NIR and NOR)metabolism-related pathways,thereby impeding FA removal and total nitrogen loss associated with N_(2)O emissions.
基金Project supported by the National Natural Science Foundation of China (No. 50238050)the Hi-Tech Research and Development Program (863) of China (No. 2002AA649250).
文摘Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.
基金supported by the Key Research&Developmental Program of Shandong Province(Nos.2021CXGC011202,2020CXGC011404)the Beijing Natural Science Foundation(No.8192004)the Beijing Major Science and Technology Projects(No.Z181100005318001)
文摘The long-term impact of fulvic acid(FA)on partial nitritation(PN)systemwas initially examined in this study.The obtained results revealed that the FA lower than 50 mg/L had negligible effect on the nitrite accumulation rate(NAR nearly 100%)and ammonium removal rate(ARR 56.85%),while FA over 50 mg/L decreased ARR from 56.85%to 0.7%.Sludge characteristics analysis found that appropriate FA(<50 mg/L)exposure promoted the settling performance and granulation of PN sludge by removing Bacteroidetes and accumulating Chloroflexi.The analysis of metagenomics suggested that the presence of limited FA(0-50 mg/L)stimulated the generation of NADH,which favors the denitrification and nitrite reduction.The negative impact of FA on the PN system could be divided into two stages.Initially,limited FA(50-120 mg/L)was decomposed by Anaerolineae to stimulate the growth and propagation of heterotrophic bacteria(Thauera).Increasing heterotrophs competed with AOB(Nitrosomonas)for dissolved oxygen,causing AOB to be eliminated and ARR to declined.Subsequently,when FA dosage was over 120 mg/L,Anaerolineae were inhibited and heterotrophic bacteria reduced,resulting in the abundance of AOB recovered.Nevertheless,the ammonium transformation pathway was suppressed because genes amoABC and hao were obviously reduced,leading to the deterioration of reactor performance.Overall,these results provide theoretical guidance for the practical application of PN for the treatment of FA-containing sewage.
基金financially supported by the National Natural Science Foundation of China(No.52170049).
文摘A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composition,evolution,and interactions.The stable operation phase(31-300 d)began after a 30 days of start-up period,reaching an average nitrite accumulation ratio(NAR)of 94.43%and a ratio of nitrite nitrogen to ammonia nitrogen(NO_(2)^(−)-N/NH_(4)^(+)-N)of 1.16.Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks,which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank,and organic matter degrading bacteria in the anoxic tank.The ammonia-oxidizing bacteria(AOB)Nitrosomonas was found to be the key functional bacteria,exhibiting an increase in abundance from 0.27%to 6.38%,due to its collaborative interactions with organic matter degrading bacteria.In-situ inhibition of nitrite-oxidizing bacteria(NOB)was achieved using a combination of free ammonia(FA)and free nitrous acid(FNA),low dissolved oxygen(DO)with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO_(2)^(−)-N/NH_(4)^(+)-N,without an adverse impact on AOB.The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria,were found to contribute to the enhanced PN performance and microbial community structure stability.These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.
基金This work was supported by the Major Science and Technology Program of Anhui,China(2021d06050001)the Anhui Provincial Natural Science Foundation of China(2108085QC148)+1 种基金the Fundamental Research Funds for the Central Universities of China(JZ2021HGQA0242)National Key R&D Program of China grant number 2019YFC1606200.
文摘We investigated the effects of Leuconostoc mesenteroides subsp.IMAU:80679 and ascorbic acid on colour development and lipid oxidation as well as protein oxidation of fermented sausages during processing.Four different groups of sausage batters were prepared for the experiment,including Nitrite group,ascorbic acid group(Aa),Leuconostoc mesenteroides subsp.group(LMS)and LMS+Aa group.The analysis of total viable count(TVC)and lactic acid bacteria(LAB)counts showed the starter culture adapted well and became the predominant population during fermentation.The redness of the LMS+Aa sausages reached 11.42±0.91,lower than 50 ppm nitrite added sausages of 13.00±1.41 but significantly higher than their individual addition(p<0.05).After ripening,the relative content of DeoMb and OxyMb in LMS+Aa sample was 56.46±1.35%,lower than Aa group of 62.01±3.38%,but higher than LMS group of 39.54±3.37%and Nitrite group of 24.06±3.34(p<0.05).The highest TVB-N,TBARS,carbonyls content and the lowest sulfhydryl content were observed in the Nitrite sausages,and these values except sulfhydryl content in the sausages treated with L.mesenteroides subsp.were higher than in that treated with both inoculation and ascorbic acid.The photochemical information from UV-vis fluorescent analysis revealed that the existing status of Nitrosylmyoglobin(NO-Mb)and Zinc protoporphyrin IX(Znpp)in inoculated sausages.The combination of L.mesenteroides subsp.and ascorbic acid resulted in the highest intensity of NOMb and the highest content of Znpp among all sausages.Therefore,these results showed that ascorbic acid combined with L.mesenteroides subsp.is able to enhance the oxidation-reduction and colour improvement and could be a potential alternative to substitute nitrite in fermented sausages.
