Failure of the side-stream deammonification process. Risk of violation of the WWTP effluent quality

Stable and efficient nitrogen removal is one of main goals of wastewater treatment. Applying deammonification, beyond many advantages, results in the risk of the WWTP effluent quality violation in case of the failure of the process. Then nitrogen load to activated sludge is increasing rapidly which could therefore lead to quality violation in activated sludge effluent. Simulation studies have been presented on the effect of deammonification failure on nitrogen removal performance in the case of a typical, medium sized WWTP (ca. 115 000 PE). The studies were based on the calibrated ASMI model of real WWTP and a fictional scenario of implementing deammonification and subsequent failure. Implementing deammonification enables SR T optimization of the sludge retention time (SRT) in its main line thanks to lower nitrogen load. Two scenarios have been shown, considering or not optimization of the SRT in WWTP. The results show that SRT optimization leads to decrease in nitrifier mass and raises difficult issues in appropriate nitrogen concentration in the effluent.