Optimizing Biogas Production and Mitigating Scum Layer Formation in Anaerobic Digestion of Market Yard Vegetable Waste Through Varied Biological Pre-hydrolysis Times

The large-scale commercial biogas industry, using Market Yard Vegetable Waste (MYVW), faces a significant challenge of scum formation during anaerobic digestion (AD). This study aims to reduce scum formation through biological pre-hydrolysis (BPH). It’s the first study to investigate the impact of varying BPH times on MYVW using the inherent microflora available in MYVW and AD digestate cultures. Experiments spanned different time intervals (0 h, 6 h, 12 h, 18 h, and 24 h), evaluating biodegradation, biogas yield, and scum formation. Comparative analyses included BPH of MYVW with and without an inoculum, along with untreated MYVW. The best BPH durations were 24 h without an inoculum and 18 h with an inoculum, guided by total volatile fatty acid accumulation. BPH with inoculum achieved the highest biogas yield (694.35 mL/gVS) at 18 h, surpassing untreated MYVW by 30.13% and BPH without inoculum by 10.39%. Longer BPH reduced scum volumes, emphasizing BPH’s significance in optimizing biogas production and waste treatment. Simultaneously, scum layer formation decreased with BPH time, reaching minimal values of 4 and 3.8% for BPH without and with an inoculum, respectively—16.7 and 25% lower than the untreated substrate.