Performance evaluation of full-scale upflow anaerobic sludge blanket reactor treating distillery spentwash

Performance of full-scale upflow anaerobic sludge blanket (UASB) reactors treating distillery spentwash was evaluated. The plant was designed to handle 650 m³ day⁻¹ of distillery spentwash having an average chemical oxygen demand (COD) concentration of 112,400 mg l⁻¹ with a HRT of 6 days. In the plant, the pH level of the influent varied from 3.50 to 4.40 but the pH of the treated effluent stabilized to a range of 7.36 to 7.68 during the study period. The operation of the reactors during study period revealed the stable conditions of the reactors, which is evident from the low COD, biochemical oxygen demand (BOD) and total solids (TS) contents in treated effluent. In the plant, the COD, BOD₅ and TS removal efficiencies were stabilized to the range of 62.19–66.59, 72.42–77.11, and 58.47–60.46%, respectively at an organic loading rate of 2.15–4.60 kg COD m⁻³ day⁻¹. The biogas production was stabilized to the range of 48,290–135,115 m³ week⁻¹ with 60% methane content. The total quantity of biogas produced ranged from 0.40 to 0.57, 1.04 to 1.71 and 0.40 to 0.56 m³ kg⁻¹ removals of COD, BOD and TS, respectively. This study concluded that the treatment of distillery spentwash using UASB reactors contributed significantly for pollution load reduction besides generating renewable in-house bio-energy.