(92b) Anaerobic Biodegradability and Potential Recovery of Biomethane from Agro-Agricultural Wastes

The anthropogenic activities especially fossil fuel-driven climate change fuel the sustainable initiatives for waste management and renewable energy. The anaerobic co-digestion of goat manure with sorghum, cotton gin trash, and food waste having different mixing ratios, volumes, temperatures, and additives was optimized in single and two-stage bioreactors. The biochemical methane potential assays (having different mixing ratios of double and triple substrates) were run in triplicates in 250 mL serum bottles. The best yielding ratios were up-scaled in fabricated 2-L bioreactors. The biodegradabilities, biomethane recoveries, and process efficacies are discussed. The co-digestion of goat manure with sorghum in a 70:30 ratio yielded the highest biomethane, which was further up-scaled to a two-stage temperature-phased process having varied nutritional conditions in fabricated 2-L bioreactors. This system yielded the highest biomethane of 266.0 mL/g_vs having an anaerobic biodegradability of 67.3%. The resulting effluent fractions; liquid and solids were separated. The liquid fraction was standardized for struvite precipitation and analyzed for plant available nitrogen and phosphate. The solid fraction was analyzed for several macro and micronutrients for application as biofertilizers. This study involving feedstock acquisition, characterization and their anaerobic digestion optimization provides fundamental information and may assist small farmers operating on-farm anaerobic digesters.