Optimization of the ensiling process of carbon-rich biomass for enhanced methane production using wastewater sludge inoculum

Abstract

This study evaluates the effect of commercial biological and chemical ensiling additives on improving the anaerobic digestibility of sugarcane bagasse, a significant agro-industrial residue. Seven additives, representing homofermentative, heterofermentative, acid-based, and yeast-based pathways, were tested at ambient temperature under anaerobic conditions and compared with untreated and fresh bagasse. The ensiling process significantly modified substrate composition, reducing water-soluble carbohydrates while increasing lactic and acetic acids and alcohol concentrations, thereby influencing methane yield and energy recovery. The most effective ensiling strategy, SILASIL ENERGY.XD (a blend of homo- and hetero-fermentative bacteria), increased methane productivity to 74.53 L/kg, compared to 61.12 L/kg for untreated ensiled bagasse. On organic total solids basis, this represented a 55.37% increase over untreated ensiled bagasse and 27.77% more than fresh bagasse, demonstrating improved digestibility and conversion efficiency. Methane energy values confirmed that effective ensiling strategies could enhance energy recovery, potentially increasing by up to 28.30%, despite some dry matter losses during storage. These findings highlight ensiling as a practical, cost-effective strategy for enhancing methane potential and supporting sustainable waste-to-energy utilization of sugarcane bagasse.