Partial nitrification process by seeding aerobic and anaerobic granular sludge

Abstract

In this study, the partial nitrification process was developed by seeding aerobic and anaerobic granular sludge into an airlift sequencing batch reactor. The effect of aeration rate on partial nitrifying granules was investigated at different ammonia concentrations. At a high aeration rate (1.72 cm/s), the nitrite accumulation rate of higher than 98% was accomplished. At a low aeration rate (0.12-0.26 cm/s), significant biomass detachment occurred on the surface of aerobic granular sludge whereas anaerobic granular sludge could maintain stable granular structure. Then, about 50% influent ammonium was oxidized to nitrite at dissolved oxygen concentration less than 1.5 mg/L. The Nitrosomonas in aerobic granular sludge was 16% after 30 d and was 33% after 80 d. The Nitrosomonas in anaerobic granular sludge was 3% after 50 d. Therefore, the development of partial nitrifying bacteria could be better in aerobic granular sludge.