Fuzzy Logic Control for saving energy in a biological nitrogen \ removal process

Many uncertain factors affect the operation of Wastewater Treatment Plants. Due to the complexity of biological wastewater treatment processes, classical methods have significant difficulties when trying to control them automatically. Consequently, artificial intelligence techniques and, specifically, fuzzy logic appears to be a good candidate for controlling these ill-defined, time-varying, non-linear systems. This paper describes the development of a Fuzzy Logic Controller to regulate the intermittent aeration in a real Wastewater Treatment Plant. The main goal of this control process is to save energy without decreasing the quality of the effluent discharged. The fuzzy controller integrates the information coming from two different signals: the Dissolved Oxygen and Reduction-Oxidation Potential values. The key steps involved in developing the fuzzy logic control are outlined.