Intrinsic molecular insights to enhancement of biogas production from kitchen refuse using alkaline-microwave pretreatment

The current study analyzed and optimized the concentration of NaOH for alkaline pretreatment of kitchen refuse for biogas production. Also, the benefits of microwave assistance in enhanced biogasification of kitchen refuse were evaluated. The TS, VS and structural changes were compared using standard experimental techniques. Molecular dynamics was investigated for the molecular level changes leading to higher biogasification in NaOHmicrowave combined pretreatment. The methane and biogas yields were calculated to validate the benefits of microwave assistance in efficient biogasification. The NaOH-microwave combined pretreatment showed higher VS production. Microwave treatment degraded and removed lignin more efficiently. Molecular dynamics studies revealed the induction of configurational instability in lignin and cellulose molecules with variable temperatures. The methane and biogas production increased with 6% NaOH concentration, and decreased at higher NaOH concentration till 10%. Microwave assistance declined the required NaOH concentration further to 4%. Thus, as compared to 6% NaOH concentration required for an efficient pretreatment, the kitchen refuse was efficiently pretreated with 4% NaOH concentration when combined with a 30 min duration microwaving. The experimental and computational data provided a detailed analysis proposing an optimized, novel and promising method to pretreat kitchen refuse for efficient and enhanced biogas production.