Microbial electrosynthesis(MES)enables the bioproduction of multicarbon compounds from CO_(2)using electricity as the driver.Although high salinity can improve the energetic performance of bioelectrochemical systems,a...Microbial electrosynthesis(MES)enables the bioproduction of multicarbon compounds from CO_(2)using electricity as the driver.Although high salinity can improve the energetic performance of bioelectrochemical systems,acetogenic processes under elevated salinity are poorly known.Here MES under 35e60 g L^(-1)salinity was evaluated.Acetate production in two-chamber MES systems at 35 g L^(-1)salinity(seawater composition)gradually decreased within 60 days,both under-1.2 V cathode potential(vs.Ag/AgCl)and^(-1).56 A m^(-2)reductive current.Carbonate precipitation on cathodes(mostly CaCO3)likely declined the production through inhibiting CO_(2)supply,the direct electrode contact for acetogens and H2 production.Upon decreasing Ca2t and Mg2t levels in three-chamber reactors,acetate was stably produced over 137 days along with a low cathode apparent resistance at 1.9±0.6 mU m^(2)and an average production rate at 3.80±0.21 g m^(-2)d^(-1).Increasing the salinity step-wise from 35 to 60 g L^(-1)gave the most efficient acetate production at 40 g L^(-1)salinity with average rates of acetate production and CO_(2)consumption at 4.56±3.09 and 7.02±4.75 g m^(-2)d^(-1),respectively.The instantaneous coulombic efficiency for VFA averaged 55.1±31.4%.Acetate production dropped at higher salinity likely due to the inhibited CO_(2)dissolution and acetogenic metabolism.Acetobacterium up to 78%was enriched on cathodes as the main acetogen at 35 g L^(-1).Under high-salinity selection,96.5%Acetobacterium dominated on the cathode along with 34.0%Sphaerochaeta in catholyte.This research provides a first proof of concept that MES starting from CO_(2)reduction can be achieved at elevated salinity.展开更多
Shortcut nitrification-denitrification,anaerobic ammonium oxidation(ANAMMOX),and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter(EGSB-BAF)integrated system.As...Shortcut nitrification-denitrification,anaerobic ammonium oxidation(ANAMMOX),and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter(EGSB-BAF)integrated system.As fed different synthetic wastewater with chemical oxygen demand(COD)of 300-1200 mg·L^(-1)and NH_(4)^(+)-N of 30-120 mg·L^(-1)at the outer recycle ratio of 200%,the influence of influent on ANAMMOX in the integrated system was investigated in this paper.The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX;however,when an influent with the low concentration of COD was used,the opposite changes could be observed.Higher influent NH_(4)^(+)-N concentration favored ANAMMOX when the COD concentration of influent was fixed.Therefore,low COD=NH_(4)^(+)-N ratio would decrease competition for nitrite between ANAMMOX and denitrification,which was favorable for reducing the negative effect of organic COD on ANAMMOX.The good performance of the integrated system indicated that the bacterial community of denitrification,ANAMMOX,and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent.展开更多
基金supported by the National Natural Science Foundation of China(No.42107242 and 51974039)Chongqing Special Support Fund for Post Doctorsupported by a Competitive Research Grant from the Office of Sponsored Research(No.OSR-2016-CRG5-2985)of King Abdullah University of Science and Technology.
文摘Microbial electrosynthesis(MES)enables the bioproduction of multicarbon compounds from CO_(2)using electricity as the driver.Although high salinity can improve the energetic performance of bioelectrochemical systems,acetogenic processes under elevated salinity are poorly known.Here MES under 35e60 g L^(-1)salinity was evaluated.Acetate production in two-chamber MES systems at 35 g L^(-1)salinity(seawater composition)gradually decreased within 60 days,both under-1.2 V cathode potential(vs.Ag/AgCl)and^(-1).56 A m^(-2)reductive current.Carbonate precipitation on cathodes(mostly CaCO3)likely declined the production through inhibiting CO_(2)supply,the direct electrode contact for acetogens and H2 production.Upon decreasing Ca2t and Mg2t levels in three-chamber reactors,acetate was stably produced over 137 days along with a low cathode apparent resistance at 1.9±0.6 mU m^(2)and an average production rate at 3.80±0.21 g m^(-2)d^(-1).Increasing the salinity step-wise from 35 to 60 g L^(-1)gave the most efficient acetate production at 40 g L^(-1)salinity with average rates of acetate production and CO_(2)consumption at 4.56±3.09 and 7.02±4.75 g m^(-2)d^(-1),respectively.The instantaneous coulombic efficiency for VFA averaged 55.1±31.4%.Acetate production dropped at higher salinity likely due to the inhibited CO_(2)dissolution and acetogenic metabolism.Acetobacterium up to 78%was enriched on cathodes as the main acetogen at 35 g L^(-1).Under high-salinity selection,96.5%Acetobacterium dominated on the cathode along with 34.0%Sphaerochaeta in catholyte.This research provides a first proof of concept that MES starting from CO_(2)reduction can be achieved at elevated salinity.
基金This research was supported by the Natural Science Foundation of China(Grant No.50378094).
文摘Shortcut nitrification-denitrification,anaerobic ammonium oxidation(ANAMMOX),and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter(EGSB-BAF)integrated system.As fed different synthetic wastewater with chemical oxygen demand(COD)of 300-1200 mg·L^(-1)and NH_(4)^(+)-N of 30-120 mg·L^(-1)at the outer recycle ratio of 200%,the influence of influent on ANAMMOX in the integrated system was investigated in this paper.The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX;however,when an influent with the low concentration of COD was used,the opposite changes could be observed.Higher influent NH_(4)^(+)-N concentration favored ANAMMOX when the COD concentration of influent was fixed.Therefore,low COD=NH_(4)^(+)-N ratio would decrease competition for nitrite between ANAMMOX and denitrification,which was favorable for reducing the negative effect of organic COD on ANAMMOX.The good performance of the integrated system indicated that the bacterial community of denitrification,ANAMMOX,and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent.
