Dissolved Oxygen Control in a Activated Sludge Process for Wastewater Treatment Plant

The Dissolved Oxygen (DO) in the reactor plays a key role in modern wastewater treatment based on Activated Sludge Process (ASP). This paper proposes a methodology to design a DO controller based on simple black-box model identification that can be applied to any ASP plant starting from standard measurements produced applying a simple ONOFF controller to the plant. The proposed control scheme is easily implementable on a commercial Programmable Logic Controller and SCADA system. It is tested on different technologies: a simulated Conventional Activated Sludge and a real fullsize Thermophilic Aerobic Membrane Reactor (TAMR) plant. A six-month experiment in TAMR has shown an improvement in the reduction of both Chemical Oxygen Demand (COD) (80. 9 % vs 66.8 %) and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{NO}_{3}$</tex> (94.5 % vs 85.3 %).