低强度超声波改善微生物燃料电池产电效能

Improve electricity generation of microbial fuel cells by low intensity ultrasound

微生物燃料电池(MFCs,M icrobial Fuel Cells)可在处理有机废水的同时获得电能,但生物体系缓慢的电子传递速率是其发展的瓶颈.为了寻求提高MFCs工作效率的途径,建立了2个有效容积为1.5 L,电极面积160 cm2的单室MFCs,设置为超声波强化反应器和对照反应器,进行对比试验.结果表明,采用强度为0.2W/cm2、频率33 kHz、超声间隔为83 h的超声波对反应器辐照10m in,在反应后期(运行2 880 h后)MFCs与对照反应器相比最大功率密度提高了6%,一个运行周期产生的总电量增加了46.5%;设置超声的反应器库仑效率(CE,Coulombic E fficiency)比对照反应器提高了25.7%.超声波强化反应器中水的pH值最小值比对照pH值最小值低0.2,超声波辐照的反应器氧化还原电位(ORP,Oxidation ReductionPotential)最小值低于对照反应器ORP最小值34.8 mV.2个反应器3 000 m in对化学需氧量(COD,Chem ical Oxygen Demand)的净化效率都达到72.9%,超声波对COD去除贡献不明显,并从低强度超声波对微生物作用的过程方面分析了上述现象.

It is possible to produce electricity in microbial fuel cells （MFCs） while accomplishing biological wastewater treatment, but slow electron transference limits the development of MFCs. To improve the electricity generation, two similar single chambered MFCs were built, which had the available volume 1.5 L, and each electrode area was 160 cm^2. One was irradiated by ultrasound, the other used as control. The MFCs was induced by ultrasound at 33 kHz in 10 rain with the ultrasound intensities of 0.2W/cm^2 every 83 hours. The result shows that in the end of the reaction（ about 2880 h）, the maximum power density of the ultrasound treatment reactor increases by 6% comparing with that of the control, and the total coulomb increases by 46.5% in one reaction cycle. The ultrasound treatment reactor＇s Coulombic efficiency （CE） is 25.7% higher than that of the control. Moreover, in the MFCs with ultrasound, the lowest pH of wastewater is lower than that in the con- trol, and the lowest oxidation reduction potential（ORP） of reactor is lower by 34.8 nV. In 3000min the two reactors＇ removal rate of chemical oxygen demand（COD） all reaches to 72.9%. The ultrasound irradiation doesn＇t increase the removal rate of COD obviously. The explanation of these differences was given according to the influence of low intensity ultrasound to the microorganisms.