Maximizing Hydrolysis and Acidification of OFMSW Post-Transportation: Toward Easily Degradable Dissolved Carbon Production

Conventional anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) yields significant quantity of digestate with high nitrogen content, posing considerable disposal challenges. The spotlight has recently been cast upon producing easily biodegradable carbon sources by hydrolysis for synergistic wastewater treatment. However, the hydrolysis during its transportation and storage prior to treatment has been commonly overlooked. This study endeavors to investigate the untapped potential for further hydrolysis and acidification of in-field OFMSW upon arriving at the treatment facilities, aiming to release more organic carbon into the hydrolysate to serve as a carbon source for biological denitrification. Results showed that lactic acid occupied about 83% of dissolved organic carbon in homogenized slurry upon its arrival at treatment facilities, and limited the bioprocess for further acidification. A remarkable volatile fatty acids (VFAs) production rate of 366 g/kg VS was achieved through enhanced acidification of OFMSW’s solid fraction, effectively breaking down proteins and hemicellulose. Notably, about 50% of chemical oxygen demand in the hydrolysate consisted of high-quality carbon sources, including VFAs and lactic acid. In the described OFMSW treatment park with the context of processing 1000 t OFMSW daily, optimizing this method could save approximately 4600 USD/day by eliminating the need for external carbon sources. Surplus hydrolysate can be further digested to produce biogas without negatively impacting biomethane potential.