Improvement of cow manure anaerobic digestion performance by three different crop straw biochars

Abstract

Anaerobic digestion (AD) is an effective bioconversion technology widely used to treat agricultural waste and reduce environmental pollution. Although AD has been commonly applied to practical social needs, low yield and reactor instability limit its performance. In this study, potato, rape, and wheat straw were pyrolyzed to biochar at 600 °C and added to a batch AD system to improve biogas yield. Biochemical methane potential test was used to assess the methane production. The results showed that the three straw biochar had similar efficiency that increased cumulative methane production (35.45%–52.66%) compared with that in the control group (818.5 mL). Potato straw biochar presented the highest cumulative methane production (1249.5 mL). Significant differences in microbial communities between biochar and control groups were noticed. The microbial community structure in the AD system was significantly related to the biochar properties. The addition of biochar increased the abundance of Methanobrevibacter in the biochar group by 2–147 times. This study provides reference for the application of straw biochar to promote methane production.