Enhanced anaerobic digestion of lignocellulosic paunch waste using potassium hydroxide pre-treatment

Alkaline pre-treatment enhances the biological accessibility and methane recovery of lignocellulosic feedstocks during anaerobic digestion. This study investigates the impact of potassium hydroxide (KOH) pre-treatment on paunch (2.5 and 12 g per 100 g paunch TS for 24 hr at 22 °C) using biochemical methane potential tests and 5 L bench-scale CSTR bioreactors. BMP tests showed significant improvements in hydrolysis kinetics and methane yield. Continuous experiments validated these findings, with volatile solids destruction increasing from 33 % for raw paunch to 61 % for 12 % KOH pre-treated paunch. Methane yield was consistently enhanced with an increase of up to 150 % compared to raw paunch. Microbial analysis revealed a shift in dominant methanogens from Methanosaeta to Methanobacterium, in response to KOH pre-treatment. While the results highlight the potential of KOH pre-treatment to improve both degradability and methane recovery, challenges related to process stability were identified, emphasizing the need for further investigation to optimise operational conditions for full-scale applications.