An up-flow anaerobic sludge blanket(UASB)reactor targeting sulfate reduction was operated under a constant TOC/S-SO2-4ratio of 1.5±0.3 g C/g S for 639 days using crude glycerol as carbon source.A filamentous and ...An up-flow anaerobic sludge blanket(UASB)reactor targeting sulfate reduction was operated under a constant TOC/S-SO2-4ratio of 1.5±0.3 g C/g S for 639 days using crude glycerol as carbon source.A filamentous and fluffy flocculant material,namely slime-like substances(SLS),was gradually accumulated in the bioreactor after the cease of methanogenic activity.The accumulation of SLS was followed by a decrease in the removal efficiencies and a deterioration in the performance.Selected characteristics of SLS were investigated to explore the causes of its formation and the effect of SLS on the UASB performance.Results showed that glycerol fermentation and sulfate reduction processes taking place in the reactor were mainly accomplished in the bottom part of the UASB reactor,as the sludge concentration in the bottom was higher.The accumulation of SLS in the UASB reactor caused sludge flotation that further led to biomass washout,which decreased the sulfate and glycerol removal efficiencies.Batch activity tests performed with granular sludge(GS),slime-covered granular sludge(SCGS)and SLS showed that there was no difference between GS and SLS in the mechanism of glycerol fermentation and sulfate reduction.However,the specific sulfate reduction rate of GS was higher than that of SLS,while SLS showed a higher glycerol fermentation rate than that of GS.The different rates in GS and SLS were attributed to the higher relative abundances of fermentative microorganisms found in SLS and higher relative abundances of sulfate reducing bacteria(SRB)found in GS.展开更多
Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,...Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,we inoculated two syntrophic dechlorinating cultures containing Dehalobacter and Dehalobacterium to sequentially transform chloroform(CF)to acetate in a BES using a graphite fiber brush as the electrode.In this co-culture,Dehalobacter transformed CF to stoichiometric amounts of dichloromethane(DCM)via organohalide respiration,whereas the Dehalobacterium-containing culture converted DCM to acetate via fermentation.BES were initially inoculated with Dehalobacter,and sequential cathodic potentials of-0.6,-0.7,and -0.8 V were poised after consuming three CF doses(500 μM)per each potential during a time-span of 83 days.At the end of this period,the accumulated DCM was degraded in the following seven days after the inoculation of Dehalobacterium.At this point,four consecutive amendments of CF at increasing concentrations of 200,400,600,and 800 μM were sequentially transformed by the combined degradation activity of Dehalobacter and Dehalobacterium.The Dehalobacter 16S rRNA gene copies increased four orders of magnitude during the whole period.The coulombic efficiencies associated with the degradation of CF reached values>60% at a cathodic potential of -0.8 V when the degradation rate of CF achieved the highest values.This study shows the advantages of combining syntrophic bacteria to fully detoxify chlorinated compounds in BESs and further expands the use of this technology for treating water bodies impacted with pollutants.展开更多
基金the Spanish Government,through the project RTI2018-099362-B-C21 MINECO/FEDER,EU,for the financial support provided to perform this researchthe China Scholarship Council (CSC,201706300052)for financial support。
文摘An up-flow anaerobic sludge blanket(UASB)reactor targeting sulfate reduction was operated under a constant TOC/S-SO2-4ratio of 1.5±0.3 g C/g S for 639 days using crude glycerol as carbon source.A filamentous and fluffy flocculant material,namely slime-like substances(SLS),was gradually accumulated in the bioreactor after the cease of methanogenic activity.The accumulation of SLS was followed by a decrease in the removal efficiencies and a deterioration in the performance.Selected characteristics of SLS were investigated to explore the causes of its formation and the effect of SLS on the UASB performance.Results showed that glycerol fermentation and sulfate reduction processes taking place in the reactor were mainly accomplished in the bottom part of the UASB reactor,as the sludge concentration in the bottom was higher.The accumulation of SLS in the UASB reactor caused sludge flotation that further led to biomass washout,which decreased the sulfate and glycerol removal efficiencies.Batch activity tests performed with granular sludge(GS),slime-covered granular sludge(SCGS)and SLS showed that there was no difference between GS and SLS in the mechanism of glycerol fermentation and sulfate reduction.However,the specific sulfate reduction rate of GS was higher than that of SLS,while SLS showed a higher glycerol fermentation rate than that of GS.The different rates in GS and SLS were attributed to the higher relative abundances of fermentative microorganisms found in SLS and higher relative abundances of sulfate reducing bacteria(SRB)found in GS.
基金supported by the Spanish Ministry of Science,Innovation and Universities projects CTM2017-91879-EXP and PID2019-103989RB-100a predoctoral grant from UAB(PIF 2017e2018).
文摘Using bioelectrochemical systems(BESs)to provide electrochemically generated hydrogen is a promising technology to provide electron donors for reductive dechlorination by organohalide-respiring bacteria.In this study,we inoculated two syntrophic dechlorinating cultures containing Dehalobacter and Dehalobacterium to sequentially transform chloroform(CF)to acetate in a BES using a graphite fiber brush as the electrode.In this co-culture,Dehalobacter transformed CF to stoichiometric amounts of dichloromethane(DCM)via organohalide respiration,whereas the Dehalobacterium-containing culture converted DCM to acetate via fermentation.BES were initially inoculated with Dehalobacter,and sequential cathodic potentials of-0.6,-0.7,and -0.8 V were poised after consuming three CF doses(500 μM)per each potential during a time-span of 83 days.At the end of this period,the accumulated DCM was degraded in the following seven days after the inoculation of Dehalobacterium.At this point,four consecutive amendments of CF at increasing concentrations of 200,400,600,and 800 μM were sequentially transformed by the combined degradation activity of Dehalobacter and Dehalobacterium.The Dehalobacter 16S rRNA gene copies increased four orders of magnitude during the whole period.The coulombic efficiencies associated with the degradation of CF reached values>60% at a cathodic potential of -0.8 V when the degradation rate of CF achieved the highest values.This study shows the advantages of combining syntrophic bacteria to fully detoxify chlorinated compounds in BESs and further expands the use of this technology for treating water bodies impacted with pollutants.
