Cultivation of aerobic granular sludge in a column bioreactor with 3 h SBR cycle time for low strength domestic wastewater

Abstract

Aerobic Granular Sludge (AGS) technology received special attention among wastewater researchers due to the compact system and simultaneous organics and nutrient removal in one single unit reactor, especially for domestic wastewater treatment. However, it is reported in the studies that the stability of AGS formation depending on organic loading rate (OLR). A low organic loading rate led to the problem of occurrence of the filamentous bacteria in the system, which disturbed the stability of compact granules formation. Therefore, researchers intended to further investigate this bottleneck of the AGS technology. This study aims to cultivate aerobic granular sludge in actual domestic wastewater at organic loading rate of 1.6 kg COD per day and COD/N/P ratio was 200/25/10. The experiment was carried out in a 2.5 L working volume of column reactor that operated with 3 h of sequencing batch reactor (SBR) cycle time for 29 days. This AGS system achieved reliability results in the treatment of domestic wastewater with a good average removal rate for COD, around 80 %. For Ammoniacal Nitrogen (AMN) and Total Phosphorus (TP), AGS system successfully treat up to the maximum of 88.6 and 71.7 %. Meanwhile, AGS size >1.0 mm was successfully cultivated with an average settling velocity of 40 m/h and 30 min Sludge Volume Index (SVI) of 60 mL/g.