Effect of Seed Sludge on Aerobic Granulation

The objective of this research was to study the effect of feed cycle on aerobic granule production in SBR system. Wastewater was a mixture of treated effluent from an ethanol factory and sugar. Average COD and BOD concentrations were 1,998 and 374 mg/L, respectively. Seed sludge was brought from an aeration tank of an activated sludge system treating municipal wastewater. Two SBR systems were used; the SBR 1 was controlled at feed cycle of 4 hours per batch while the SBR 2 was controlled at 6 hours per batch. Each reactor had volume of 8 liters fed with an organic loading rate of 0.90 - 1.08 kilogram BOD per cubic meter per day. It was found that COD removal efficiencies of SBR 1 and SBR 2 were 66.97 % and 65.36 %, respectively. For TKN removal efficiencies, they were 47.12 % and 49.04 %, respectively. Most of aerobic granules in both SBRs were larger than 0.85 millimeters. Maximum settling velocities of granules from SBR 1 and SBR 2 were 128.1 and 156.5 meters per hour, respectively.

Keywords : feed cycle; aerobic granule; SBR system; COD and TKN removal