Anaerobic digestion of gliricidia sepium co-digested with pig manure using automated and portable digester

Abstract

Promoting biogas as a renewable energy source is strengthened by decentralized anaerobic digestion systems at the community level, providing an innovative approach to managing organic waste and sustaining energy. The anaerobic digestion of pig dung co-digested with gliricidia sepium were experimented with over 30 days all using both fabricated and automated digesters. This study used a mixing ratio of the substrate to an inoculum of 1:1 for a hydraulic retention time (HRT) of 30 days in triplicates. The physicochemical and microbial characteristics of the substrates and digestate were analyzed using standard procedures. A statistical analysis was conducted using ANOVA to assess the data. There was a reduction in cellulose concentration by 2% m.m−1 after the thermo-alkaline pretreatment, which indicates a modification in the structure that aids the breakdown of the biomass during digestion Experimental results show that pig dung co-digested with gliricidia sepium produced a gas yield of 0.986772m3 and 0.50845m3 from the automated and fabricated digester respectively. When comparing treated and untreated Gliricidia sepium, the raw sepium had a higher C/N ratio, ranging from 7 to 8. Iron, zinc, aluminum, copper, Biological oxygen demand, Chemical oxygen demand as well as T.alkalinity, T.nitrogen, T.phosphate, T.carbon, potassium, sulfate, calcium, magnesium, and manganese well as total solids, volatile solids all showed an increase after pre-treatment. This research has shown that significant methane content of gas (58.26%) can be generated from Gliricidia sepium co-digested pig manure even at small-household levels.