Optimizing low-voltage boosting for an air-cathode microbial fuel cell with an anion exchange membrane in a 246 L wastewater treatment reactor

Abstract

Microbial fuel cells (MFCs) have been applied in wastewater treatment; however, the secondary use of recovered electricity has been rarely investigated. Here, we aimed to optimize electricity recovery and the secondary use strategy using a 246 L reactor packed with 12 tubular air-cathode MFC units using an anion exchange membrane (AEM) as the separator. Parallelly connected eight MFC units exhibited a maximum electric power, 3.5-fold higher than a single MFC, from 16 to 58 mW; however, the power density was the highest for a single MFC or two MFCs considered together, at 0.10 and 0.11 W m⁻², respectively, and decreased for more than three MFCs. Electricity recovery from the MFCs by changing the combination ratios of the MFCs and two DC/DC converters, LTC3105 and ADP5090, was the most efficient (60%) considering the connection of a single MFC and ADP5090, respectively. The 12 pairs of MFCs and ADP5090 in 245 L wastewater powered an aeration pump to achieve 0.39 L h⁻¹ aeration flow in wastewater, an air fan to have 12.8 L h⁻¹ air-flow, and lit two LEDs. Thus, the electricity generated by MFCs treating wastewater could be used to operate various devices, although improvements in individual MFCs are necessary for practical implementation.