Preparation of sludge-corn stalk biochar and its enhanced anaerobic fermentation

In order to realize efficient utilization of stalk and sludge, mixed biochar was prepared from corn stalk and sludge to optimize the characteristics of anaerobic fermentation gas production. The mixed biochar was prepared under different carbonization temperature, raw material ratio, heat preservation time and heating rate, and was added to anaerobic fermentation as a supplement, the relationship between the physicochemical properties of biochar and anaerobic fermentation performance was investigated. The findings revealed that methane production up to 269.23 mL/g VS when the carbonization temperature was 600 °C, the ratio of raw materials was 1:1, the holding time was 90 min and the heating rate was 10 °C/min, and compared with the addition of pure sludge, pure corn stalk and blank control group, the cumulative methane production increased by 36.13%, 37.32% and 47.1% respectively. The biochar's particular surface area and pore structure only affect methane production in a certain range. The link between the characteristics of carbon materials and the generation of methane through anaerobic fermentation is further studied using the theoretical framework provided by this study. • Proposed sludge-corn stalk biochar to promote anaerobic fermentation of corn stalk. • Sludge-corn stalk biochar increased the cumulative methane production by 47.1%. • The specific surface area of biochar effected the biological CH 4 production.