Biogas Production Potential from Organic Matters in Hydrolysate After Hydrothermal Pretreatment of Waste Biomass

Hydrothermal pretreatment has gained significant attention as a promising approach to pretreat lignocellulosic biomass due to its ability to effectively degrade biomass structure while consuming relatively low energy. However, organic-rich wastewater is generated as a byproduct of this process, and the liquid phase of the hydrolysate requires appropriate treatment. In this study, spent coir medium produced after mushroom cultivation was hydrothermally pretreated, and the liquid phase of the hydrolysate was anaerobically digested to recover biogas. With different hydrothermal pretreatment reaction temperatures (180-300℃), the physicochemical properties of hydrolysates were differentiated. While the removal ratio of COD during anaerobic digestion was not affected by physicochemical properties of hydrolysate, the lignocellulosic biomass degrading byproducts formation seemed closely linked to the biogas production yield. Therefore, optimizing the hydrothermal pretreatment temperature for lignocellulosic biomass is critical to minimizing undesirable byproduct formation and enhancing the biogas production efficiency from hydrolysate during anaerobic digestion.