Assessment of organic loading rate by using a water tank digester for biogas production in Bangladesh

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The anaerobic digestion technology has many advantages and is a sustainable way to produce energy, solve the crisis on energy shortage, and reduce waste stream and carbon footprint. In this field experiment, a mixture of food, fruits, and vegetable waste, dairy manure, and inoculum was anaerobically digested in a constructed water tank digester. This study was performed at ambient temperature under different organic loading rates (OLRs), which were increased every two weeks. Results showed that the optimum feedstock-to-inoculum ratio is 0.4, which resulted in highest specific biogas and methane yields (0.44 and 0.28 Nm3/kg VS, respectively). With the OLRs, the highest yield was observed at 1.4 kg VS/m3 average feeding. When the feedstock-to-inoculum ratio was increased from 0.4 to 0.8, the effect on biogas yield and the volatile solids decreased. Hence, the total cumulative biogas production was approximately 18.5 Nm3 per reactor volume. The pathogen concentration, which was determined in the feedstock and the effluent samples, revealed that the reduction efficiency was relatively low. On the basis of the performance of this field study, emphasizing household organic waste composed with other feed materials to produce bioenergy was feasible. Anaerobic co-digestion produces biogas, contributes to sustainable waste management, and reduces environmental pollution. This scientific study can play a fundamental role in implementing this technology at the household level for efficient biogas production in Bangladesh and worldwide.