Effect of organic loading rates (OLR) on production of methane from anaerobic digestion of vegetables waste

In this study, experiments were conducted to investigate the production of biogas from vegetable wastes by using anaerobic digestion process. The complete-mix, pilot-scale digester with working volume of 70 l was used. The experimental protocol was defined to examine the effect of the change in the organic loading rate on the efficiency of the production of biogas and to report on its steady-state performance. The digester was operated at different organic feeding rates of 1.4, 2 and 2.75 kg VS/ (m.d). The biogas produced had methane composition of 49.764% and biogas production rates of 0.12-0.4 m biogas/(kg VS input). The reactor showed stable performance with highest methane and yield (0.25 mCH4/kg VS) with VS reduction of around 88% during loading rate of 1.4 kg VS/(m.d). As the organic loading rate was increased, the VS degradation and biogas yield decreased. Based on data from this study, OLR of 1.4 kg VS/(m.d) is suggested as design criteria with methane production rate of 0.25 mCH4/kg VS input and successful implementation of anaerobic digestion as the method of waste treatment leads to the regional utilization of renewable energy resources, energy requirements and costs.