A large amount of sludge is inevitably produced during sewage treatment.Ultrasonication(US)as anaerobic digestion(AD)pretreatment was implemented on different sludges and its effects on batch and semi-continuous AD pe...A large amount of sludge is inevitably produced during sewage treatment.Ultrasonication(US)as anaerobic digestion(AD)pretreatment was implemented on different sludges and its effects on batch and semi-continuous AD performance were investigated.US was ef-fective in sludge SCOD increase,size decrease,and CH_(4)production in the subsequent AD,and these effects were enhanced with an elevated specific energy input.As indicated by semi-continuous AD experiments,the mean daily CH_(4)production of US-pretreated A^(2)O-,A^(2)O-MBR-,and AO-AO-sludgewere 176.9,119.8,and 141.7 NmL/g-VSadded,whichwere 35.1%,32.1%and 78.2%higher than methane production of their respective raw sludge.The US of A^(2)O-sludge achieved preferable US effects and CH_(4)production due to its high organic con-tent andweak sludge structure stability.In response to US-pretreated sludge,amore diverse microbial community was observed in AD.The US-AD system showed negative net energy;however,it exhibited other positive effects,e.g.,lower required sludge retention time and less residual total solids for disposal.US is a feasible option prior to AD to improve anaer-obic bioconversion and CH_(4)yield although further studies are necessary to advance it in practice.展开更多
Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirme...Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52192683,51925807,and 52221004)the National Science Fund for Distinguished Young Scholars of China(No.52125003)the Key Research Program of Frontier Sciences,CAS(No.ZDBS-LY-DQC014).
文摘A large amount of sludge is inevitably produced during sewage treatment.Ultrasonication(US)as anaerobic digestion(AD)pretreatment was implemented on different sludges and its effects on batch and semi-continuous AD performance were investigated.US was ef-fective in sludge SCOD increase,size decrease,and CH_(4)production in the subsequent AD,and these effects were enhanced with an elevated specific energy input.As indicated by semi-continuous AD experiments,the mean daily CH_(4)production of US-pretreated A^(2)O-,A^(2)O-MBR-,and AO-AO-sludgewere 176.9,119.8,and 141.7 NmL/g-VSadded,whichwere 35.1%,32.1%and 78.2%higher than methane production of their respective raw sludge.The US of A^(2)O-sludge achieved preferable US effects and CH_(4)production due to its high organic con-tent andweak sludge structure stability.In response to US-pretreated sludge,amore diverse microbial community was observed in AD.The US-AD system showed negative net energy;however,it exhibited other positive effects,e.g.,lower required sludge retention time and less residual total solids for disposal.US is a feasible option prior to AD to improve anaer-obic bioconversion and CH_(4)yield although further studies are necessary to advance it in practice.
基金the financial support from the National Natural Scientific Foundation of China(No.52000020)the National Natural Scientific Foundation of China(No.21876022)。
文摘Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.
