Sorghum stover and winery solid wastes co-digestion: application of iron oxide nanoparticles for biogas yield optimisation

Abstract One approach to addressing energy security issues is to produce renewable and sustainable bioenergy using abundant waste resources through anaerobic co-digestion (AcoD). However, the lignocellulosic nature of these biomass resources makes them recalcitrant, and pretreatment is required to make them more amenable to conversion. Iron oxide nanoparticles (ION) have been shown to increase methane yield significantly when added to biomass resources. This study aimed to investigate the effect of ION application on Sorghum stover (SS) and Winery solid waste (WSW) under mesophilic conditions. Hydrothermal synthesis was used to obtain Fe 3 O 4 nanoparticles. Biomethane potential (BMP) tests were carried out in semi-continuous batch reactors with and without ION singly and combined SS: WSW (1:1) during a 30-day retention period. The results showed that the ION application on WSW delivered a higher biogas yield (380 mL), indicating an increase of 162% in biogas production compared to the sample without ION (145 mL). In addition, CH4 generation went from 30 to 114 mLCH4, indicating a 280% increase. However, adding ION to SS inhibited CH4 production. The study found that ION addition significantly improved biogas yield, especially with WSW, where the increase was more than triple, of interest to bioenergy and waste management practitioners. Graphic Abstract