Nutrient Removal from Municipal Wastewater in a Pilot-scale Plant with A²/O Process Operated at Low SRT by Ex-situ Bioaugmentation

Dang Cong Peng, Qiong Wan, Yun Han, Liying Pei, Jilin Wei, Zhengfu Wang, Sheping Wang, Hongfang Sun



Enhancing nutrient removal from municipal wastewater by bioaugmentation was investigated in a pilot plant operated in A2/O process. Reject water from sludge treatment was used as a feed for ex-situ cultivation of nitrifier-contained activated sludge in a new process named RAO for bioaugmentation. The experimental results showed that ex-situ bioaugmentation was very effective for enhancing nutrient removal. Ammonium and phosphorous concentrations in the effluent in mainstream could be reduced to less than 1mg/L at a HRT of 10h and SRT of 8d. FISH test proved that nitrifier community of activated sludge in side-stream was identical to that in mainstream, which resulted in little nitrification loss during bioaugmentation.

Keywords:Municipal wastewater; nutrient removal; activated sludge; reject water; bioaugmentation