单室无膜微生物电解池中阴极生物膜的电活性

摘要

降解有机质的电产甲烷(electromethanogenesis)技术在生物能(CH4)的生产、废水处理、地下水和土壤(及沉积物)生物修复等领域有着巨大的发展潜力.寻找简捷的方法获取高活性的生物阴极是该技术当前发展面临的一个突出问题.以最有应用潜力的单室无膜微生物电解池(SCMMEC)为反应器,对以葡萄糖为可发酵物质代表的SCMMEC阴极上生物膜的评估表明,可利用SCMMEC处理含葡萄糖的废水来富集电活性生物阴极.当外压为0.8 V时,富集的2个生物阴极的电流密度可分别达到0.59 A/m2和0.62 A/m2.但该法获得的生物阴极活性仍然比较低,是阴阳极中的电流限制电极.进一步的介体影响评估表明,生物阴极的电活性不受溶液中可能存在的电子介体的影响.在低剂量缓冲盐(6 mmol/L的磷酸盐)下的长期运行显示,0.8 V外压下生物阴极的活性在62 d和153 d时持平,到275 d时已有明显下降.长期直流通电单向极化导致的离子浓缩,甚至盐沉积,可能是生物阴极活性下降的主要原因.%Electromethanogenesis of degrading organics has great potential in bioenergy (CH4) production, wastewater treatment, groundwater bioremediation, soil and sediment bioremediation.Enriching biocathode with high activity is currently one of the prominent problems to deal with for its development.The cathodic biofilms in glucose-fed SCMMEC exhibited electroactivity.This suggested that wastewater containing glucose could directly be used to enrich biocathode through SCMMEC.Two microbial biocathodes had current density (compared to the geometric surface area of the electrode) of 0.59 A/m2 and 0.62 A/m2 under 0.8 V applied cell voltage, respectively.However, relative to the bioanode activity, their electroactivity was still lower.They were the current-limiting electrodes in the system.The current with fed-batch mode operation suggested that possible redox mediators or suspended cells did not affect the biocathode electroactivity upon the medium complete replacement.With the medium containing 6 mM phosphate, the biocathode electroactivity showed no difference at day 62 and 153 under 0.8 V.However, the biocathode electroactivity decreased at day 275.Ions concentrating and salt precipitation due to long-term one direction polarization with DC power lead to the activity loss.