Ferrous sulfate as an in-situ anodic coagulant for enhanced bioelectricity generation and COD removal from landfill leachate

Abstract

Landfill Leachate is a heavily contaminated wastewater. MFCs (Microbial Fuel cells) are unique bioreactors, which utilize the catalytic activity of microbes for converting the chemical energy stored in organic-rich streams for bioelectricity production. MFCs represent an auspicious technology to treat landfill leachate and generate bioelectricity. Here, we evaluated the addition of ferrous sulfate as anodic coagulant as well as a media component to enhance the MFC performance. The Box-Behnken Design model of Response surface methodology (RSM) was found suitable for the determination of optimal conditions for the removal of chemical oxygen demand (COD). COD removal of 78.6% was achieved with coagulation alone at pH 8, reaction time of 90 min, and a coagulant dose of 3 g/L. Ferrous sulfate addition to MFC, significantly improved COD removal. 99.6% removal of total COD was achieved from 75% of landfill leachate, at a retention period of four days; whereas, with 100% leachate as anodic feed, 98.7% COD was removed on the third day. The volumetric power density of 6644.6 mW/m3 was achieved without any catalyst using flexible graphite sheets as electrodes. This study revealed that the integration of coagulation with MFC technology enhanced the treatment efficiency as well as power generation for landfill leachate.