In order to enhance nitrogen removal of sewage treatment processes in cold areas or seasons

a cold-adapted ammonia-oxidizing functional flora was obtained by domestication of activated sludge and used to augment the ammonia oxidation function in an anaerobic-anoxic-aerobic(A2/O)process operated at(14±1)℃.The seed sludge was collected from the secondary sedimentation tank of a local urban sewage treatment plant and domesticated in a sequencing batch reactor(SBR)for five operational cycles with selective medium at(14±1)℃.Loading with semi-soft fiber filler

the SBR was operated for another five operational cycles to immobilize the cold-adapted ammonia-oxidizing functional flora.The results showed that the ammonia oxidation capacity of the inoculated activated sludge was enhanced remarkably after domesticating for the five operational cycles with NH3-N removal of 79.5% when the initial NH3-N ranged from 205—236 mg·L-1 in the SBR.After the next 5 operational cycles the cold-adapted ammonia-oxidizing functional flora was immobilized on the filler as biofilm.When the cold-adapted ammonia-oxidizing biofilm was put into the aerobic pool of the A2/O process with a mass ratio of 3.24%

the average ammonia removal in the process increased from 65% to 78%.The COD and total nitrogen removal was significantly improved as well.However

the ammonia removal in the low temperature A2/O process dropped slowly along with running time.Thus

the bioaugmentation effect in the long run should be investigated in the future.