Rapid method of aerobic granular sludge bioreactor start-up for domestic wastewater treatment

Abstract

This study presents a rapid method on how to speed up aerobic granular sludge (AGS) cultivation and ensure excellent and stable removal performance during bioreactor operation for domestic wastewater treatment. This new strategy consists of start-up the bioreactor using only anaerobic granular sludge (AnGS) as a seed and feeding with crude sewage extracted from a full-scale Extended Aeration Plant. This experiment used a 2.5 L lab-scale sequencing batch reactor (SBR). The bioreactor operated at low dissolved oxygen (DO) concentration controlled at the value of 2.0 mg/L and below. After 60 days of operation, it clearly showed that almost 90% of AnGS seeds turned from black color to brown. The physical characterization analysis showed that the average sizes were unchanged, and the granules remained compact. Also, the SBR operation monitored with brown granules showed stable removal performance. Average removal efficiencies during steady-state cycles at room temperature of COD, ammoniacal nitrogen, and phosphate reached 84%, 92%, and 100%, respectively.