Methanogenesis suppression and increased power generation in microbial fuel cell during treatment of chloroform containing wastewater

Chloroform is a commonly found solvent in industrial wastewater and is very toxic if present in high concentration. Chloroform degradation in anaerobic processes has been reported earlier and it has also been used as a methanogenesis suppressor in rumen and rice fields. Methanogenesis is undesirable in a microbial fuel cell (MFC) operation, as it results in substrate competition between methanogens and exoelectrogens, thereby reducing the electricity output. Hence, an attempt has been made in this research work to study the effect of chloroform on the performance of MFCs and its effectiveness as methanogenesis suppressor. MFCs with different chloroform dosages in batch as well as continuous mode (0 mM, 8 mM, 16 mM and 22 mM; 0 mM and 22 mM) were operated. High open circuit voltages in batch MFC22 (781 mV) and 53 % higher peak power densities in dosed continuous MFC confirmed its efficiency as a methanogenesis suppressor. Further experimentations showed 74 % lower internal resistance in dosed MFCs. Higher coulombic efficiencies of 31.2 % (MFC22) and 18 % (MFCC22) were noted in dosed reactors than the control reactors (MFC0 - 23.8 % and MFCC0 - 8%). At the end of batches, chloroform concentration was found to be negligible, confirming its degradation in MFC. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.