Optimizing autoclave pretreatment and inoculum-to-substrate ratio for enhanced anaerobic digestion of poultry slaughterhouse wastewater.

The poultry slaughter industry's substantial water usage and wastewater generation necessitate effective wastewater management strategies. This study explores the optimization of autoclave pretreatment and inoculum to substrate ratio (ISR) for improving the anaerobic digestion (AD) of poultry slaughterhouse wastewater (PSWW). Using response surface methodology (RSM), optimal conditions were determined to be a pH of 11, a pretreatment time of 60 min, and an ISR of 2. Under these conditions, the methane yield achieved was 385.872 mL CH₄/g VS_added, representing a 3.17% increase compared to control 2 (374 mL CH₄/g VS_added). The biochemical methane potential (BMP) test confirmed this result, showing a methane yield of 394 mL CH₄/g VS_added, which was 5.34% higher than the control 2. Furthermore, under optimal conditions, autoclave pretreatment effectively increased the soluble chemical oxygen demand (sCOD) from 60.03% to 82.55%, demonstrating enhanced solubilization of particulate matter. Ammonia levels were also reduced by 24.5%. This study suggests that autoclave treatment is unsuitable under pH 5 and pH 8 conditions due to protein aggregation. Although autoclave pretreatment has a minimal effect on methane production at pH 11, this approach remains cost-inefficient.