ABSTRACT
This study focuses on optimising substrate ratio, the ratio of municipal solid waste landfill leachate (LL) to sewage sludge (SS) for treating them through an anaerobic co-digestion process. LL and SS were mixed in five different ratios based on their volatile solid concentrations. Physicochemical analyses such as volatile solids (VS), total solids (TS), and chemical oxygen demand (COD) were performed. Daily biogas generation was measured using a 5 mL syringe. The experiment was performed for three cycles with a hydraulic retention time (HRT) of 15 days per cycle. At the end of the three cycles, the substrate ratio 25% LL:75% SS showed the highest TS, VS, and COD reductions and daily biogas production than any other ratio. The highest TS, VS, and COD reductions in this study were 72.5%, 71.7%, and 80%, respectively. Similarly, 25% LL:75% SS generated the highest biogas yield of 0.138 m3/kgVS removed, compared to other substrate ratios. Hence, from the study, it is clear that when LL (25%) and sewage sludge (75%) are co-digested, the efficiency of anaerobic treatment increased with better yield of biogas than anaerobic digestion of both the substrates performed individually.
