Enhancing direct interspecies electron transfer through co- immobilization of anaerobic microbes using a conductive sponge

Abstract

Anaerobic Digestion (AD) is a biological process which can produce methane by treating organic waste. Recently, it has been discovered that adding conductive materials (CMs) to the AD process can induce direct interspecies electron transfer (DIET) between exoelectrogenic and electrotrophic bacteria, enhancing the efficiency of methane production. However, in a continuous operation, washout of CM remains a challenge today especially in upflow anaerobic sludge blanket (UASB) reactors. Thereby, in this study, enhancing DIET by co-immobilizing anaerobic microbes in a nickel conductive sponge synthesized via the electroless plating method to improve AD performance was attempted. Nickel-plated Melamine sponge (MS) and Polyurethane sponge (PS) were evaluated to select a suitable sponge for the AD process. Despite higher biomass attachment on MS compared to PS, nickel peeling was observed, leading to the selection of PS instead. In the AD experiment, Ni plated PS achieved a higher TOC removal rate, suggesting enhanced organic matter removal and process stability through DIET.