KOH pretreatment enhances methane production from poultry slaughterhouse sludge compared to NaOH

This study evaluated the effects of alkaline pretreatments with NaOH and KOH on the anaerobic digestion of poultry slaughterhouse flotation sludge (PSFS), a protein- and lipid-rich residue with low biodegradability. The pretreatments were tested at five concentrations (0.02–0.50 g g −1 VS substrate) under mesophilic batch conditions at 37 °C. KOH demonstrated superior performance, enhancing sludge solubilization, reducing lipid content, and accelerating the onset of biogas production compared to NaOH. The highest methane yield (573.5 mL N g −1 VS) was obtained with 0.50 g KOH g −1 VS, representing a 53.2% increase over the untreated control. Additionally, methane content reached 82.2%, and organic matter removal improved significantly. Although higher concentrations delayed the onset of biogas production, these treatments enhanced energy recovery and may add agronomic value to the digestate. The findings highlight the potential of KOH pretreatment as a promising strategy to improve biogas production from agro-industrial protein- and lipid-rich waste, thereby supporting circular economy initiatives in the poultry sector.