Fractional order PI control strategy on an activated sludge wastewater treatment process

Lately, the eco-friendly concept have impacted all the human activities. The wastewater treatment plant (WWTP) are now subject to optimization processes required for reaching the strict regulations applied on the discharged waters. Efficiency and costs are also key terms in this context, thus manually operation of these plants is not accepted anymore. The activated sludge process is the most complex and energy consuming part of a WWTP. Two robust Pi controllers - a conventional PI and a fractional order PI - on the dissolved oxygen concentration are presented in this paper having the goal of decreasing the operation costs, increasing the performance and rejecting the disturbances. The controllers were designed and simulated using a mathematical model tuned based on the data from the WWTP of Romanofir, Talmaciu.