Sustainable valorization of water primrose with cow dung for enhanced biogas production

In this study, the effects of alkaline pretreatment (2% NaOH) of water primrose on its biogas production efficiency and anaerobic co-digestion of cow dung were investigated. A scanning electron microscope (SEM) was used to analyze the changes in main compositions and physico-chemical structure of water primrose after pretreatment and untreated biomass. Furthermore, the experiments evaluate the efficiency and optimization mixing ratio of co-digestion using water primrose and cow dung. The pretreatment of water primrose at different periods for the examination of the biodegradability matters in the substrate and biogas production. Among the three mixing ratios of co-substrate tested, the best performance in this study was achieved at mixing ratio 2:1 (water primrose to cow dung, w/w) for 2 weeks' pretreatment time on grass, including all measurements as biogas production (8610 mL), methane concentration (68.2%), and percentage of total solids (70.84%), volatile solids (64.76%), and chemical oxygen demand (66.55%) removal efficiency.