Improve electricity generation of microbial fuel cells by low intensity ultrasound

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. One was irradiated by ultrasound, the other used as control. The MFCs was induced by ultrasound at 33 kHz in 10 min with the ultrasound intensities of 0.2 W/cm 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 control, and the lowest oxidation reduction potential (ORP) of reactor is lower by 34.8 mV. In 3000 min 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.