Performance And Microbial Community Characteristics Of The River Sediment Microbial Fuel Cell

Sediment microbial fuel cell(SMFC)is a special type of microbial fuel cell with anode buried in the sediment and cathode placed in the water.SMFC could be used as power supply of low-power instrument and in situ bioremediation technology in river sediment.In this study,single-anode SMFCs and multiple-anode SMFCs were constructed with river sediment to investigate the electricity generation,degradation of organic matter in sediment and microbial community structure.Long-term performance of multiple-anode SMFCs was compared with single-anode reactors.The degradation of specific antibiotics in sediment were analyzed in SMFCs.The effect of the indigenous organic matter content in sediment on the SMFC performance was investigated.SMFCs with loss of ignition(LOI)of 5% showed the most reliable performance in this study.High organic content(LOI 10-16%)led to higher but very unstable voltage output because of biogas accumulation and worm activities.SMFCs with low organic content(1-3%)showed stable but low power output because of lack of substrate.High throughput sequencing results indicate that enrichment of Desulfobulbaceae on the anode biofilm was related to higher power outputs,and Thermodesulfovibrionaceae was found associated with system startup.Long-term performance(400 days)of multiple-anode SMFC showed that multiple anodes extended electricity generation from SMFCs due to increased anode surface area,but the distance between the anodes(1-4 cm)showed limited effects on power output.The power output was stable when temperature was above 25?.Electricity generation was seriously inhibited when temperature was below 20?,but system recovered once ambient temperature rose.Worms' growth in the sediment destabilized the power output,deteriorated the water environment and affected the microbial communities in sediments.The degradation of specific antibiotics in sediment were analyzed in SMFCs.The results showed that tetracycline and oxytetracycline in sediment could be degraded effectively with the removal rate of higher than 60% in SMFCs.Although the addition of carbon source into the sediment could improve the energy output of the system,the degradation of antibiotics was not promoted because the biodegradability of external carbon source is better than antibiotics.The addition of anaerobic sludge into the sediment reduced the internal resistance of SMFC,but did not promote the power output and the degradation of antibiotics.And there was a positive correlation between the relative abundance of Methylophilaceae and the removal rate of antibiotics in the river sediments near the anode.