Enhanced methane production from algal biomass through short duration enzymatic pretreatment and codigestion with carbon rich waste

Abstract

Anaerobic digestion of algal biomass faces problems of low digestibility due to cell wall resistance and inappropriate carbon to nitrogen ratio. In the present work a short duration method involving fungal crude enzyme based pretreatment of algal biomass was disclosed. The effect of fungal crude enzymes on algal biomass was assessed qualitatively through visual and microscopic observations and quantitatively through measuring algal biomass solubilization. Up to 50% biomass COD solubilization was observed within 150 min of pretreatment under optimal conditions. Subsequent anaerobic digestion of pretreated algal biomass showed production of 324.38 mL CH₄ g⁻¹ VS_fed as compared to 254.73 mL CH₄ g⁻¹ VS_fed from untreated algal biomass. Interestingly, methane yield increased up to 413.89 mL g⁻¹ VS_fed when pretreated algal biomass was codigested with cattle dung. On the other hand, sugarcane bagasse had a negative effect on algal biomass codigestion due to its poor digestibility. Overall, the present attempt showed promising results by improving methane yield from algal biomass though pretreatment and codigestion.