The Influence of Biocatalytic Plant Extracts on Biogas Production from Kitchen Wastes at Cryo-mesophilic Temperature Regimes

Abstract

Radicalization in waste-to-energy systems are on the rise to meet human energy demands. Biogas generation from kitchen wastes is one such scheme, though affected by poor yields and methane levels at low temperatures. In this research, biocatalytic extracts with fermentative properties were hereby assessed on their potential to fasten these processes and increase the biogas yield at ambient temperatures. The variations in kitchen waste substrate anaerobic parameters and elemental composition as well as biogas yields and methane levels were monitored in a 28-day retention period. Three 40-liter batch and unstirred bio-digesters containing biocatalysts Terminalia b., Acanthaceae spp. and a control setup were used. The results indicated rapid saccharification rates in the samples with additives. Terminalia b. additives exhibited high volatile solids hydrolysis rate of 98.3% followed by Acanthaceae spp. (50.8%) and control sample (29.4%). Similar trends were observed in organic carbon reduction as the levels of nitrogen, phosphorus and sulfur linearly increased. The biocatalysts did not affect substrate pH, volatile fatty acids and alkalinity levels. Terminalia b. sample produced 2.32 folds higher while Acanthaceae spp. sample produced 1.375 folds higher than the control sample. Terminalia b. methane levels were highest (45.475±0.922%) followed by the control sample (41.750±1.401) and Acanthaceae spp. sample (39.275±0.263%) after 28-day retention period at 19.5±0.5°C. Use of these biocatalysts in biofuel synthesis can thus optimize biogas production leading to greener economies.