Studi Kinetika Pengaruh Massa Biochar Terhadap Produksi Biogas Berbahan Baku Campuran Limbah Makanan dan Sewage Sludge pada Kondisi Mesofilik

Abstract

Biochar is a porous material that can be used as an additive in anaerobic digestion to enhance biogas production. This study examines the biogas production from a mixture of food waste and sewage sludge using batch reactors and evaluates the biogas yield resulting from the addition of biochar to obtain the kinetic constants of biogas production. The ratio of food waste to sewage sludge is 4:1, while the ratio of substrate to inoculum is 1:1. The fermentation process was carried out in an 11 L reactor at a temperature of 35°C, pH 7±0.2, and stirring speed of 80 rpm, with varying amounts of biochar added: 0 g/L, 0.5 g/L, and 1.5 g/L. Analytical parameters measured included pH, alkalinity, TS, VS, TSS, VSS, COD, biogas volume, and biogas composition. The accumulated biogas yield was then modeled using modified Gompertz, logistic, and cone equations and analyzed using nonlinear regression methods. The results showed that the addition of biochar mass improved outcomes compared to the control, where the pH and alkalinity values were respectively 6.48-7.3 and 1800-4000 mg/L. The highest biogas production was achieved with the addition of 2 g/L of biochar, averaging 1.285 L/mg.VS.day, with biogas compositions of CH4, CO2, and H2S at 80.99%, 18.21%, and 0.25% respectively. The addition of biochar also reduced the organic content in anaerobic digestion. The average reductions in VS and COD were 80.95% and 87.95%, respectively. The modified Gompertz, logistics, and cone kinetic models were capable of representing the kinetics of biogas production rates in this study. The logistic equation achieved the best accuracy level with the addition of 2 g/L of biochar, with kinetic constants A, k_hyd, and n respectively at 1.4179 ml/mg VS, 0.1584 ml/mg VS, and 4.8484. The best kinetics were evaluated using the coefficient of determination (R2) and root mean squared error (RMSE) values of 0.9925 and 0.083, indicating that the biogas production could be explained using the logistic model. Therefore, the addition of biochar shows potential to enhance biogas production and support sustainable waste management on an industrial scale.