The Electricity Production In Thermophilic Microbial Fuel Cell

Microbial fuel cell is an emerging environmental biotechnology that exoelectrogens convert organic waste into electricity in anode.Nowadays,most of researchers focuses on mesophilic(20-40?)conditions instead of at high temperature(55?)conditions.Therefore,ethanol was used as an electron donor to construct a two-chamber thermophilic microbial fuel cell(TMFC)in this study.The electrogenic performance was analyzed,and the microbial composition was characterized by high-throughput sequencing and 16S rRNA clone library sequencing.Through experimental research,we have obtained the following conclusion:the open circuit potential of TMFC is about 650 mV;and the maximum voltage is about 550 mV;the maximum power density is 437 mW/m~2;the Coulomb efficiency of TMFC is 20.5±6.0%.The similarity of the bacteria associated with the uncultured bacterial clone A55_D21_H_B_C01 was 99%,accounting for 90.9%of all bacteria in the TMFC biofilm.This uncultured bacterium provides a new direction for high temperature microbial microorganisms.In addition,we explored the electrical properties of microbial fuel cells at different temperatures(low temperature and extreme thermophilic temperature).However,under low temperature(15?)and high temperature(70?)conditions,the electricity production is unstable,and the electrogenic microorganisms still need long-term culture.Accumulation of volatile fatty acids(VFAs)such as acetate and propionate inhibit the activity of anaerobic digestion(AD).Electrodialysis(ED)can be used to separate products such as acetate and propionate in fermentation broth,and the electrical energy generated by high-temperature microbial fuel cells can be used to drive electrodialysis.Therefore,this paper considers the effects of metabolite concentration and medium on the recovery of acetate and propionate.The experimental results show that the removal of acetate and propionate occurs once direct current was applied to electrodialysis(ED)even in the presence of medium.However,at a low metabolite concentration of 3 g/L,the current efficiency was below 70%,even around 30%.The energy consumption reached a maximum value of 46.0 kW·h/kg.The internal resistance of the dilution chamber was considered to be the main factor of high energy consumption of ED.In the ED-AD system,we found that the applied current can significantly reduce bacterial activity,and no methane production was detected within 20 days after the ED experiment.Therefore,it is necessary to separate the anaerobic bacteria from the fermentation broth to maintain the activity of the bacteria in the AD.Therefore,this paper studies the electrolysis performance of high-temperature microbial fuel cells and uses the electrodialysis process to remove accumulated volatile fatty acids.It provides new ideas and solutions for the development of anaerobic digestion and electrodialysis technology.