THE EFFECT OF ORGANIC LOADING RATE ON MILK WASTEWATER TREATMENT USING SEQUENCING BATCH REACTOR (SBR)

In this study, four aerobic sequencing batch reactors (SBRs) were operated under the same conditions for the treatment of milk wastewater at different organic loading rates (OLRs). Cylindrical Plexiglas reactors were run for 56 days (including 21 days of acclimatization and 35 days of data gathering). Effective volume, influent wastewater flowrate, and sludge retention time (SRT) of reactors were 5.5 L, 3.5 L/d, and 10 d, respectively. The average COD removal efficiency for the reactors R1, R2, R3, and R4 with influent OLRave values of 633, 929, 1915, and 3261 gCOD/md were 95, 96, 95, and 82 percent, respectively. The average effluent suspended solid (SS) for all reactors was lower than 44 mg/L. Also, except for R4 with an average effluent turbidity of 270 NTU, other reactors met the Iranian wastewater emission standard (50 NTU). In addition, the average sludge volume index of reactors R1 to R3 was found to be lower than 67 mL/g. According to the results, the overall variation of COD removal efficiency versus influent OLR shows a decreasing rate with a correlation factor of 0.8 (R).