Stimulating anaerobic degradation of biodegradable plastics by promoting direct interspecies electron transfer via...

Although biodegradable plastics (BPs) are promoted as environmentally friendly, they exhibit low degradability and slow degradation rates under anaerobic conditions, creating challenges similar to conventional plastics. This study explores the effects of activated carbon and magnetite on the anaerobic digestion of BPs. Results showed that conductive materials improved digestion rates for readily degradable BPs but had no effect on recalcitrant ones unless pretreated. Magnetite increased the maximum methane production rates of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), cellulose diacetate, and thermoplastic starch by 37 %, 18 % and 15 %, respectively, at an organic loading (OL) of 8 gVS/L. Supplementation was especially effective at high OLs, where unamended controls were inhibited by excessive acidification. Metagenomic analysis revealed enrichment of direct interspecies electron transfer-capable microorganisms such as Syntrophaceticus and Methanosarcina, and associated functional genes, in the supplemented groups. The findings highlight conductive material supplementation as a promising complementary strategy for improving the anaerobic biodegradation of BPs.