Modelling of Nitrogen Compounds Removal in Activated Single Sludge Systems

Esposito et al. (2002) have recently proposed a mathematical steady-state model far the design of the pre¬denitrification systems, taking into account four substrates (soluble and particulate biodegradable organic matter, ammonia nitrogen and nitrate nitrogen). The model is related to completely stirred reactors and is based on mass balance equations of the above cited substrates and two biomasses (heterotrophic and autotrophic microorganisms). Unlike the existing design models, based on parameters such as sludge age or organic load factor, the proposed model is supported by the current kinetics and stoichiometry knowledge of the processes. This approach makes it possible to solve completely the design problem, with explicit expressions of the model unknowns. The model also permits to evaluate a priori the system applicability. In this paper the model proposed by Esposito et al. (2002) has been extended, considering the biomasses decay.