Enhancing the biogas generation potential of Cumbu Napier grass through hydrothermal pretreatment

This study aims to investigate the feasibility of hydrothermal pretreatment of cumbu napier grass for biochemical methane production. The hydrothermal pretreatment of the cumbu napier grass was carried out with 10 % total solids loading rate at various pressures (1, 5 and 10 bar) to disrupt the lignin, hemicellulose and cellulose bonding. The hydrothermal pretreated cumbu napier grass is mixed with cow dung at different ratios, such as (1:0, 3:1, 1:1 and 1:3). The study evaluates the hydrothermal pretreatment effectiveness of cumbu napier grass treated at 10 bar and mixed with an equal ratio of cow dung, resulting in the highest biogas yield of 18.64 L/kg with 44 to 56 % methane content. Also, this pretreatment condition confirmed high total solids (66.00 %), cellulose (79.64 %), hemicellulose (67.20 %) and lignin (56.40 %) destruction efficiency. Additionally, the FT-IR analysis and SEM analysis results indicated structural modification in the pretreated biomass, in turn enhancing the biodigestibility and confirmed the best approach to convert waste to energy in a sustainable way with a 3-year payback for a 1000 kg/day biodigester.