Effect of periodic complete anolyte replacement on the long term performance of a four air cathodes single chamber microbial fuel cell

Abstract

Periodic anolyte replacement was investigated as a means of enhancing the performance of a four air–cathodes single chamber microbial fuel cell (4ACMFC) during its long term operation. The 938 cc unit exhibited very good stability over a period of 53 days in continuous mode operation, attributed to reduction of the growth of antagonistic non-electrogenic bacteria in the bulk solution as a result of the periodic anolyte replacement. Moreover, the MnO2 catalyst layer coating remained stable for approximately 105 days of total cell operation, both in batch and continuous mode. During the long term continuous operation at 32 °C, the steady-state cell voltage was equal to 0.413 ± 0.023 V, the coulombic efficiency ranged from 14 to 16.5 %, while the COD removal remained stable at an average value of 80 %. A maximum power density Pmax of 10 W/m3 was achieved. The 4ACMFC was further assessed at different temperatures and conductivities. Its optimum performance was obtained at 32 °C while the ionic strength was not a limiting factor of the cell performance. The aforementioned results highlight periodic anolyte replacement as a potential operation mode for more stable MFC performance over time.