Pretreatment of Distillery Wastewater from Vitamin C Synthesis Industry by Upflow Anaerobic Sludge Blanket (UASB) Reactor

Feasibility of a 2.3 m₃ pilot-scale mesophilic upflow anaerobic sludge blanket (UASB) reactor was evaluated for the treatment of distillery effluent from a fermentation-based vitamin C (Vc) synthesis industry. In the 252-day test period, successful startup was achieved within 100 days using digested sludge. Afterward, the organic loading rate (OLR) was increased gradually from 6 to 11.8 kg COD/m³/day by increasing the influent COD in steps from 5,000 to 9,000 mg/L and by decreasing the hydraulic retention time (HRT) to 10 h. The upflow velocity was maintained at 0.52 m/h. COD removal efficiencies >85% and biogas productivity of 3.2–5.9 m³/m_r³/day were obtained. The biogas contained 73% of CH₄. The volatile suspended solids/total suspended solids ratio of sludge increased from 0.48 at the beginning to 0.83 by the end of the reactor operation. Similarly, the specific methanogenic activity (SMA) improved from 0.20 to 0.82 gCH₄-COD/gVSS ⋅ day. These results indicated that the UASB process is effective and efficient for the pretreatment of the distillery wastewater from Vc production industry.