In situ Physicochemical and Microbial Changes During Kitchen Refuse Biogasification

Abstract

The kitchen refuse evaluated for biomethane showed a potential of 32l/kg dry wt. with the highest percent methane content of 63, demonstrating kitchen refuse as a good biomethanation candidate. Physical factors like, texture, size and the substrate proximates affect biomethanation. A 50 μm resolution SEM degradation pattern study gave a micro-level understanding of the gradual physical changes during biomethanation. The substrate degradation pattern signified the actual consumption and decomposition of the material. An appreciably high methane yield compared to substrates like agro-wastes and cow-dung is attributed to the low C/N ratio of the fed substrate. An increase in the percent easy-to-degrade organic input can ensure a good amount of quality biogas. Methane and VFA correlated well, wherein the methane percentage increased while the VFA value decreased. A better biomethanation was associated with the acclimatised inocula and wetness of the sample. Promising biomethanation-mediating microbes with diverse enzymatic activities indicate at the possibility of formulating a niche-specific effective microbial consortium. While formulating effective microbial consortia for enhanced biomethanation, bacterial groups with enzymatic activities such as amylase, cellulase, lechithinase, and lipase were successfully isolated and screened. Elemental analyses of the digestate established its safety as manure.