Cobalt oxide nanoparticles as a new strategy for enhancing methane production from anaerobic digestion of noxious aquatic weeds

This study investigated the effect of cobalt oxide nanoparticles (Co3O4-NPs) supplementation on anaerobic mi-crobial population changes and anaerobic digestion (AD) performance and production. Co3O4-NPs (3 mg/L) showed the maximum enhancement of biogas yield over the cow dung (CD) as control and the co-digestion process of CD with water hyacinth (WH) by 58.9 and 27.2 %, respectively. Furthermore, methane (CH4) yield was enhanced by 89.96 and 43.4 % over CD and co-digestion processes, respectively. Additionally, the micro-biological assessment analysis using VIT (R) gene probe technology showed that Co3O4-NPs enhance the viability of total bacterial cells by 9 %. The techno-economic analysis reflects the revenue of this strategy on the highest net energy content of biogas, which was achieved with 3 mg/L Co3O4-NPs and was 428.05 kWh with a net profit of 67.66 USD/m3 of the substrate. Therefore, nanoparticle supplementation to the AD process can be considered a promising approach to enhance biogas and CH4.