A hybrid microbial fuel cell membrane bioreactor with a conductive ultrafiltration membrane biocathode for wastewater treatment

A new hybrid, air-biocathode microbial fuel cell-membrane bioreactor (MFC-MBR) system was developed to achieve simultaneous wastewater treatment and ultrafiltration to produce water for direct reclamation. The combined advantages of this system were achieved by using an electrically conductive ultrafiltration membrane as both the cathode and the membrane for wastewater filtration. The MFC-MBR used an air-biocathode, and it was shown to have good performance relative to an otherwise identical cathode containing a platinum catalyst. With 0.1 mm prefiltered domestic wastewater as the feed, the maximum power density was 0.38 W/m² (6.8 W/m³) with the biocathode, compared to 0.82 W/m² (14.5 W/m³) using the platinum cathode. The permeate quality from the biocathode reactor was comparable to that of a conventional MBR, with removals of 97% of the soluble chemical oxygen demand, 97% NH₃-N, and 91% of total bacteria (based on flow cytometry). The permeate turbidity was <0.1 nephelometric turbidity units. These results show that a biocathode MFC-MBR system can achieve high levels of wastewater treatment with a low energy input due to the lack of a need for wastewater aeration.