On-Site Sanitary Wastewater Treatment System Using 720-L Stacked Microbial Fuel Cell: Case Study

Abstract

Scaling up of a microbial fuel cell (MFC) is a challenging task and researchers are still struggling to achieve acceptable results when treating real wastewater at the field scale. In this study, a field-scale stacked MFC, consisting of six individual MFCs with a volume of 120 L each, was designed, constructed, and operated for on-site sanitary wastewater treatment. The first time the long term performance evaluation of such large-scale MFC with a total working volume of 720 L, treating actual sewage, is presented in this study. The stacked setup consisted of one hexagonal central chamber surrounded by six peripheral MFCs, MFC-1, MFC-2, MFC-3, MFC-4, MFC-5, and MFC-6. Cathode catalysts, Co0.5Zn0.5Fe2O4 and Sn5Cu84, were used in these stacked field-scale MFCs on carbon felt base material and a competitive performance was observed for both the catalysts. Goethite was used as an anode catalyst over a carbon felt anode for all MFCs. Chemical oxygen demand (COD) removal efficiency was observed to be directly related to hydraulic retention time (HRT) and 78.45% ± 19.12% of COD removal efficiency was observed at an HRT of 18 h. However, COD removal efficiency increased to 87.29% ± 7.28% with an increase in HRT to 36 h. Therefore, this stacked MFC system produced a final effluent with a COD of 303 ± 50 mg/L and produced a maximum power of 61 mW, which was used to illuminate the toilet premises at night.