Mitigation of ammonia and volatile fatty acids inhibition in dry anaerobic digestion of chicken manure by biochar prepared at varying pyrolysis temperatures

Abstract

This study examined the impact of various types of biochar on dry anaerobic digestion of chicken manure under the combined stress of ammonia and volatile fatty acids (VFAs). Total ammonia nitrogen (TAN) concentration at 9069 mg/L and total VFAs (TVFA) concentration at 33646 mg-HAc/L decreased the biogas production potential of chicken manure by approximately 50 %. The introduction of biochar prepared at 800 °C (BC800) enhanced the maximum biogas production rate of the inhibited anaerobic digestion mixture by 121.3 % and reduced the anaerobic digestion period by 38.6 %. The superior electrical conductivity, high specific capacitance value, large pore volume, and large specific surface area of BC800 significantly improved its performance in facilitating dry anaerobic digestion. BC800 enriched Bathyarchaeia and Methanosaeta, fostering the breakdown of propionic acid and bolstering acetoclastic methanogenesis. This study provides valuable experience for dry anaerobic digestion of chicken manure in future applications.