Review of impact of nanoparticle additives on anaerobic digestion and methane generation

Anaerobic digestion is a globally used biochemical process to convert the organic matter present in wastes into an energy rich biogas with methane as the major constituent. Implementing additives in the anaerobic digestion process enhances biogas production. Recent studies have revealed that nanoparticles additives influence the anaerobic digestion. Interspecies electron transfer (IET) is the main mechanism behind methane production. Apart from traditional IET routes, like IET through hydrogen and formate, direct interspecies electron transfer (DIET) through conducive materials have gained importance. This paper reviews DIET via abiotic conducive materials and describes the impact of various nanoparticle additives on anaerobic digestion. The paper also discusses the positive and negative impacts of nanoscale materials on biogas production. This study confirms that proper screening of nanoparticles based on physicochemical characteristics and other factors supportive of DIET can enhance the performance of the anaerobic digestion process, thereby increasing biogas generation.