The Effect of Thermochemical Pretreatment on Lignin Breakdown and Biogas Yield from Co-Digested Sawdust and Cowdung

This study investigates the production of biogas through the co-anaerobic digestion of cow dung and sawdust, utilizing thermochemical pretreatment to enhance lignin breakdown. A 50:50 and a 75:25 mixture of the substrates (Cowdung:sawdust) were subjected to sodium hydroxide pretreatment and thermal conditioning at 80°C. Lignin content reduced from 31.94% to 22.73%. The results demonstrated approximately a 43% increase in biogas yield for both the 50:50 and 75:25 substrate ratios. A four-day earlier gas production onset was recorded for pretreated substrates compared to untreated samples. The methane content of the biogas reached 56% (50:50 ratio) and 60% (75:25 ratio), with hydrogen sulfide at about 1% in both ratios. Process parameters such as pH, and temperature were measured. This study provides a scalable approach for waste-to-energy applications and demonstrates the role of pretreatment in improving substrate digestibility and biogas yield.