Cultivation of aerobic granular sludge for pentachlorophenol(PCP) degradation under microaerobic condition(DO concentration was controlled at 0.2—0.7 mg/L) was studied in this paper. Anaerobic granules were selected ...Cultivation of aerobic granular sludge for pentachlorophenol(PCP) degradation under microaerobic condition(DO concentration was controlled at 0.2—0.7 mg/L) was studied in this paper. Anaerobic granules were selected as inoculum. The changes of appearance were observed and the variations of SVI, VSS/TSS, PN/PS and the size of sludge were measured during cultivating. The capabilities for degradation of PCP, AOX and COD_ Cr were also studied. Observations on mature granules were carried out by scanning electron microscope, and the results indicated bacillus was dominant on the surface of granules while in the inner of granules both bacillus and coccus were the dominant microorganisms. K, Na, Fe, Ca, Mg, Ni, Co, Mn, Cu and Zn were detected in the granules by element analysis.展开更多
Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under mic...Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.展开更多
Microaerobic Fe(Ⅱ) oxidation process at neutral pH, driven by microbes can couple to carbon assimilation process in iron-rich freshwater and marine environments;however, few studies report such coupled processes in p...Microaerobic Fe(Ⅱ) oxidation process at neutral pH, driven by microbes can couple to carbon assimilation process in iron-rich freshwater and marine environments;however, few studies report such coupled processes in paddy soil of the critical zone in South China. In this study, rhizosphere soil from flooded paddy field was used as the inoculum to enrich the microaerophilic Fe(Ⅱ)-oxidizing bacteria(FeOB) in gradient tubes with different Fe(Ⅱ) substrates(FeS and FeCO_3) and ^(13)C-biocarbonate as inorganic carbon source to track the carbon assimilation. Kinetics of Fe(Ⅱ) oxidation and biomineralization were analyzed, and the composition and abundance of the microbial community were profiled using 16 S rRNA gene-based highthroughput sequencing. Results showed that microbial cell bands were formed 0.5–1.0 cm below the medium surface in the inoculated tubes with Fe(Ⅱ) substances, while no cell band was found in the non-inocula controls. The protein concentrations in the cell bands reached the highest values at 18.7–22.9 mg m^L(-1) on 6 d in the inocula tubes with Fe(Ⅱ) substrates. A plateau of the yields of ^(13)C-biocarbonate incorporation was observed during 6–15 d at 0.44–0.54% and 1.61–1.98% in the inocula tubes with FeS and FeCO_3, respectively. The inocula tube with FeS showed a higher Fe(Ⅱ) oxidation rate of 0.156 mmol L^(-1) d^(-1) than that with FeCO_3(0.106 mmol L^(-1) d^(-1)). Analyses of X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy revealed that amorphous iron oxide was formed on the surface of rod-shaped bacteria after Fe(Ⅱ) oxidation.Relative to the agar only control, the abundances of Clostridium and Pseudogulbenkiania increased in the inocula tube with FeS,while those of Vogesella, Magnetospirillum, Solitalea, and Oxalicibacterium increased in the inocula tube with FeCO_3, all of which might be the potential microaerophilic FeOB in paddy soil. The findings in this study suggest that microbes that couple microaerobic Fe(Ⅱ) oxidation to carbon assimilation existed in the paddy soil, which provides an insight into the iron-carbon coupling transformation under microaerobic conditions in the critical zone of the iron-rich red soil.展开更多
Sequencing biofilm batch reactor(SBBR) under micro-aerobic condition was applied to the treatment of aniline-contaminated wastewater in this study.Hydraulic retention time(HRT) of 12—36 h and dissolved oxygen(DO) con...Sequencing biofilm batch reactor(SBBR) under micro-aerobic condition was applied to the treatment of aniline-contaminated wastewater in this study.Hydraulic retention time(HRT) of 12—36 h and dissolved oxygen(DO) concentration of 0.1—0.5 mg/L were selected as the operating variables to model,analyze and optimize the process.Five dependent parameters,aniline(AN),chemical oxygen demand(COD),ammonium,total nitrogen(TN) and total phosphorus(TP) removal efficiencies as the process responses,were studied.From the results,increase in DO concentration could promote the AN,COD and ammonium removal;increase in HRT could also lead to increase of the AN and ammonium removal,but might decrease COD removal due to endogenous respiration and soluble microbial products.In the SBBR system,24 h for HRT and 0.5 mg/L for DO concentration were chosen as the optimum operating condition.The actual removal efficiencies of COD,AN and ammonium under the optimum operating condition were 98.37%,100%and 89.29%,respectively.The experimental findings were in close agreement with the model prediction.The presence of glucose could promote bacterial growth and has positive influence on AN degradation and ammonium removal.展开更多
基金The Guangdong Natural Science Foundation(No. 31430) State Key Laboratory of Pulp and Paper Making Engineering, South China University of Technology(No. 200335) and the Laboratory of Cellulose and Lignocellulosics Chemistry, Chinese Academy of Sciences(No.K 147)
文摘Cultivation of aerobic granular sludge for pentachlorophenol(PCP) degradation under microaerobic condition(DO concentration was controlled at 0.2—0.7 mg/L) was studied in this paper. Anaerobic granules were selected as inoculum. The changes of appearance were observed and the variations of SVI, VSS/TSS, PN/PS and the size of sludge were measured during cultivating. The capabilities for degradation of PCP, AOX and COD_ Cr were also studied. Observations on mature granules were carried out by scanning electron microscope, and the results indicated bacillus was dominant on the surface of granules while in the inner of granules both bacillus and coccus were the dominant microorganisms. K, Na, Fe, Ca, Mg, Ni, Co, Mn, Cu and Zn were detected in the granules by element analysis.
基金funded by the National Natural Science Foundations of China(41420104007,41330857,and 41701295)Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306041)and Special Support Program(2016)
文摘Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41571130052, 41701295 & 41271263)the Guangdong Natural Science Funds for Distinguished Young Scholars (Grant No. 2017A030306010)
文摘Microaerobic Fe(Ⅱ) oxidation process at neutral pH, driven by microbes can couple to carbon assimilation process in iron-rich freshwater and marine environments;however, few studies report such coupled processes in paddy soil of the critical zone in South China. In this study, rhizosphere soil from flooded paddy field was used as the inoculum to enrich the microaerophilic Fe(Ⅱ)-oxidizing bacteria(FeOB) in gradient tubes with different Fe(Ⅱ) substrates(FeS and FeCO_3) and ^(13)C-biocarbonate as inorganic carbon source to track the carbon assimilation. Kinetics of Fe(Ⅱ) oxidation and biomineralization were analyzed, and the composition and abundance of the microbial community were profiled using 16 S rRNA gene-based highthroughput sequencing. Results showed that microbial cell bands were formed 0.5–1.0 cm below the medium surface in the inoculated tubes with Fe(Ⅱ) substances, while no cell band was found in the non-inocula controls. The protein concentrations in the cell bands reached the highest values at 18.7–22.9 mg m^L(-1) on 6 d in the inocula tubes with Fe(Ⅱ) substrates. A plateau of the yields of ^(13)C-biocarbonate incorporation was observed during 6–15 d at 0.44–0.54% and 1.61–1.98% in the inocula tubes with FeS and FeCO_3, respectively. The inocula tube with FeS showed a higher Fe(Ⅱ) oxidation rate of 0.156 mmol L^(-1) d^(-1) than that with FeCO_3(0.106 mmol L^(-1) d^(-1)). Analyses of X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy revealed that amorphous iron oxide was formed on the surface of rod-shaped bacteria after Fe(Ⅱ) oxidation.Relative to the agar only control, the abundances of Clostridium and Pseudogulbenkiania increased in the inocula tube with FeS,while those of Vogesella, Magnetospirillum, Solitalea, and Oxalicibacterium increased in the inocula tube with FeCO_3, all of which might be the potential microaerophilic FeOB in paddy soil. The findings in this study suggest that microbes that couple microaerobic Fe(Ⅱ) oxidation to carbon assimilation existed in the paddy soil, which provides an insight into the iron-carbon coupling transformation under microaerobic conditions in the critical zone of the iron-rich red soil.
基金the National Major Water Project of China(No.2013ZX07201007)the Fund supported by State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2013DX06)
文摘Sequencing biofilm batch reactor(SBBR) under micro-aerobic condition was applied to the treatment of aniline-contaminated wastewater in this study.Hydraulic retention time(HRT) of 12—36 h and dissolved oxygen(DO) concentration of 0.1—0.5 mg/L were selected as the operating variables to model,analyze and optimize the process.Five dependent parameters,aniline(AN),chemical oxygen demand(COD),ammonium,total nitrogen(TN) and total phosphorus(TP) removal efficiencies as the process responses,were studied.From the results,increase in DO concentration could promote the AN,COD and ammonium removal;increase in HRT could also lead to increase of the AN and ammonium removal,but might decrease COD removal due to endogenous respiration and soluble microbial products.In the SBBR system,24 h for HRT and 0.5 mg/L for DO concentration were chosen as the optimum operating condition.The actual removal efficiencies of COD,AN and ammonium under the optimum operating condition were 98.37%,100%and 89.29%,respectively.The experimental findings were in close agreement with the model prediction.The presence of glucose could promote bacterial growth and has positive influence on AN degradation and ammonium removal.
