Enhanced anaerobic digestion under medium temperature conditions: Augmentation effect of magnetic field and composites formed by titanium dioxide on the foamed nickel

Abstract

There is global interest in developing clean energy, especially using green production strategies. Increasing the production of methane by anaerobic digestion (AD) is a green strategy that greatly benefits agricultural waste management. This study investigated the effects of combining a static magnetic field (SMF) with a novel porous conductive compound (TiO2-FNi) with bioaffinity as an additive in the anaerobic digestion and methanation of corn stover. Total experimental methane production with an optimized TiO2-FNi concentration (2.82 g L−1) in an 11.4 mT SMF was 44.71% greater than the control. Analysis of the composition of the microbial community showed the greatest relative abundance of the electroactive microorganisms Bacteroidota and Sytrophomonas spp. (phylum Firmicutes), 52.06%, in TiO2-FNi colonies. These microorganisms increase electron exchange through direct interspecies electron transfer with methanogens to increase methane yield. We propose a possible mechanism for the increased methane production due to the TiO2-FNi –SMF combination, which promotes microbial growth and reproduction and increases direct interspecies electron transfer (DIET) between microorganisms. Recovery of the TiO2-FNi composite reached 99.29%, which indicates great potential for recycling the material. The energy conversion efficiency of AD using the TiO2-FNi –SMF combination was 43.68%, which was 13.20% greater than the control.