Soft magnetic ferrite for enhanced anaerobic digestion of food waste: Effects on methane production and magnetic recovery.

Soft magnetic ferrite (SMF) is a potentially efficient anaerobic digestion (AD) additive that can be recovered simultaneously along with the microorganisms it carries. In this study, two typical SMFs (FeO and γ-FeO) were compared in batch experiments to investigate their effects on food waste AD and to examine the recovery characteristics of both the SMFs and the microorganisms they carried after AD. The results showed that FeO and γ-FeO addition increased methane production by 31% and 68% respectively, compared with the control treatment. Both SMF materials and enriched microorganisms were effectively adsorbed post-AD using a magnet. The observed enhancement in biomethanization after SMF addition was likely due to enhanced syntrophic acetate oxidation and hydrogenotrophic methanogenesis, and direct interspecific electron transfer. γ-FeO outperformed FeO due to its high recycling rate and ability to promote Methanosarcina growth. This study provides a potential economically efficient solution for developing AD enhancement technologies.