Keywords: aerobic granules, bioaugmentation, biological nitrogen removal, aerobic granulation, microbial immobilisation, nitrification, nitrifying granules, wastewater treatment, activated sludge, ammonia removal rate
Application of nitrifying granules to improvement of nitrification activity in activated sludge process
Nitrifying granules were used to improve nitrification performance of activated sludge process under high organic load. After inoculation of nitrifying granules, nitrification activity immediately increased, and kept for at least 70 days. Fluorescence in situ hybridisation analysis confirmed that nitrifying bacteria were retained in the granules even though nitrifying granules had been served in the organic wastewater treatment reactor for 70 days. Nitrification performance strongly depended on C/N ratio of the influent wastewater. Nitrifying granules that had been statically stored for 100 days could completely recover ammonia removal rate within 15 days after inoculation to ammonia-rich solution.