Troubleshooting of Nitrification Upsets at Pharmaceutical Wastewater Treatment Plant

A synthetic pharmaceutical manufacturing facility was experiencing recurring upsets of nitrification at its wastewater treatment plant. The main treatment train consisted of trickling filters followed by a conventional activated sludge process with ostensibly adequate treatment capacity (average F/M of 0.1, COD/MLSS-based). An evaluation of the plant’s operating conditions and performance indicated that some of the instances of nitrification failure were a direct result of nitrifiers washout due to a nitrogen deficiency followed by increased TKN loads. Ammonia supplementation in an amount adequate to maintain effluent nitrate concentration of 25 mg/l at all times was implemented with success. In some other instances a lower nitrification efficiency was associated with periods of higher organic loading with likely attendant higher concentration of inhibitory chemicals. Quite expectantly, a number of factors indicated a generally inhibitory nature of the wastewater, with slow nitrification and heterotrophic kinetics. Consequently, a much longer sludge age (lower F/M) than customarily assumed is required to maintain consistent nitrification for such difficult wastewater and measures to address this problem are being implemented.