Impact of temperature reduction on partial nitrification in a batch biofilter

The impact of temperature reduction on the stability and recoverability of partial nitrification in a batch biofilter were investigated in present study. The results showed that NH 4 + -N removal rate, NO 2 –N accumulation rate and effluent NO 2 –N/NH 4 + -N ratio of the batch biofilter could maintain at about 60%, 95% and 1.3 respectively when the temperature was controlled at 20∼25°C. Within this temperature range, the batch biofilter had good partial nitrification performance and could provide suitable and stable influent conditions for the subsequent anaerobic ammonia oxidation (ANAMMOX). When the biofilter was shocked by low temperature, its COD removal ability and partial nitrification performance could both basically restore to its original level via resuming 25°C for a period of time.