The Effect of the Mixing Ratio of Sewage Sludge and Organic Fraction of Municipals Solid Waste on Biogas Production in Anaerobic Digestion Process

Anaerobic digestion was the best way to treat organic waste biologically. It uses microorganisms to biodegrade biosolids without oxygen, producing biogas and compost. The study involved conducting batch experiments to investigate biogas and fertilizer production. Three digestive systems (A, B, and C) with three different mixing ratios were operated simultaneously and had a retention time of thirty-five days. The organic fraction of municipal solid waste, sewage sludge, and bacteria were employed in the experiments. The Al-Rustamiyah wastewater treatment plant was the source of the sewage sludge. The organic municipal solid waste fraction was utilized as materials, including fruit peels, rotten fruits, vegetable peels, eggshells, rotten vegetables, and garden leaves. The bacterial strain used in this research was E. coli, isolated directly from the local sewage sample and selected as an eco-friendly bacteria after conducting many tests. The digester's initial temperature was 30 °C, and it reached a high of 42 °C on the 16th day. Three digesters had initial pH values (6.7, 6.3, 6) and final values (7.3, 7.1, 7). The results showed good anaerobic digestion performance. The digester (C) achieved the highest biogas production, with a maximum cumulative biogas production value of 0.0549 m3. It also demonstrated removal efficiencies of 78.30% for TS, 89.13% for VS, 86.36% for BOD5, and 80.5% for COD. Additionally, the moisture content was measured at 43.30%. The anaerobic digestion’s final product was used as a high-quality fertilizer.