Behaviour of an activated sludge plant removing nitrogen during rain events: facts and simulations
Résumé
This study deals with WWTP loading and performance when receiving combined sewage. A yearly data set from a plant operating at very low F/M and being intermittently aerated was analysed statistically to compare loading and discharge during dry and wet weather. The results are rather unexpected, as they show that despite some loading increase, the nitrogen removal performance is only slightly affected, whereas higher soluble COD discharge is observed! This approach was supplemented with dynamic simulations with the calibrated ASM1, which confirmed and explained the observed behaviour of the plant under shock load. The results of this study contribute to the global ongoing reflection on WWTP design and effluent regulation.