Effect of organic loading rate on the performance of aerobic SBR treating anaerobically digested distillery wastewater

The influence of organic loading rate (OLR) on the performance of aerobic sequencing batch reactor (SBR) treating anaerobically digested distillery wastewater (ANDW) was investigated in this study. The SBR is operated with four different OLRs of 1.8, 3.6, 5.4 and 9.0 kg COD/(m³ day) by varying the influent COD concentration of 3600, 9000, 12000 and 17300 mg/L, respectively, and the hydraulic retention time was kept constant at 24 h. From the experimental investigation, it was found that the reactor performance decreases when OLRs increases. The COD and BOD removal efficiency is 74 and 96 % at 3.6 kg COD/(m³ day), and with increase in the OLR to 9.0 kg COD/(m³ day) results in the decrease in COD and BOD removal efficiency to 43 and 84 %, respectively. TKN removal efficiency also drops from 99 to 66 % when OLRs was increased to 9.0 kg COD/(m³ day). Higher OLRs of 5.4 and 9.0 kg COD/(m³ day) results in accumulation of inorganics in the reactor causing destabilization of the reactor and process failure, and thereby significantly affect the reactor performance in terms of organic removal. The OLR of 3.6 kg COD/(m³ day) was found to be optimum for SBR for the effective treatment of ANDW combined with domestic wastewater.