Novel bioaugmentation process to enhance anaerobic digestion of municipal sewage sludge

The imperative shift to a circular economy, driven by population growth, urbanization, and economic development, highlights the importance of recovering resources from waste streams. Anaerobic digestion (AD) is promising for stabilizing organic wastes and producing renewable methane-rich biogas. However, AD faces challenges, including operational instability, fatty acids accumulation, ammonium inhibition, and low yields. This study investigates the applicability of a novel Ydro Process® bioaugmentation on municipal sewage sludge anaerobic digestion. The process led to pre-hydrolysis of sewage sludge, as evidenced by an increase in volatile fatty acids (VFA), from 134 mg HAc/L in raw TWAS to 997 mg HAc/L in augmented sludge and improved soluble chemical oxygen demand (SCOD) yields. Additionally, the viscosity decreased by 41 % in the Ydro Process® bioaugmented sludge. Biogas production significantly increased from 732 mL/day to 1338 mL/day during semi-continuous digestion, with methane yield rising from 116 mL/g TCOD_added to 218 mL/g TCOD_added. Microbial analysis revealed an enhanced population of hydrogenotrophic methanogens.