Optimization of biogas produced from Cassia tora and Jatropha curcas using response surface methodology

Abstract

In this study, the optimization of three process parameters were assessed as controlling factors for the optimum generation of biogas by RSM using Cassia tora as the substrate. The three factors; mass of substrate, volume of water and digestion time were assessed on daily basis and optimized by RSM using rotatable central composite design (RCCD) to determine their optimum level. Considering various experimental data, the optimized result showed that optimum biogas production was achieved at 0.40g mass of substrate, 4.23mL of distilled water and at 5 days digestion time. The percentage yield of biogas was analyzed using 'Geotech-5000 Biogas analyzer'. The results shows 48.7% of CH4, 3.7% of CO2, 11.2% of O2 and 36.6% of impurities as the best yield for the biogas obtained. The result for RSM analysis shows that volume of water, digestion time and mass of substrate are important parameters for biogas production. The R2 values for CH4, CO2, O2 and impurities were found to be 0.8325, 0.7994, 0.8274, and 0.7814 respectively which shows a good correlation of the model values.