Contributing to a better method for controlling wastewater treatment " A case study of the Ruwaimiya plant "
Abstract
This study focuses on comparing four control strategies for the aeration process in wastewater treatment plants: the first relies on ON/OFF cycling, the second is sequential dissolved oxygen control, the third is sequential ammonium control, and the last is multivariable predictive control.
MATLAB software was utilized to design all four control systems within the Simulink environment, interfacing them with the aeration system and subsequently comparing the simulation outcomes. The results demonstrated that the ON/OFF method caused issues of over-aeration and high energy consumption. Sequential dissolved oxygen control required an extended period to achieve stability, thereby reducing treatment process efficiency. In contrast, sequential ammonium control reduced the treatment time to seven hours and contributed to notable energy savings by lowering the required dissolved oxygen setpoint. Regarding predictive control, it was found to accelerate the system response, achieving a treatment duration of only about three hours. Furthermore, it enabled the prediction of biological load quantity, consequently reducing the amount of air supplied for the treatment process. This resulted in substantial savings in electrical energy consumption compared to the previously mentioned control strategies.
A demonstrative laboratory-scale model of the aeration process was implemented, which can be interfaced with the predictive control system developed in the Simulink environment after changing the values of tank capacity, inflow and return flow, as well as biomass concentration, the aim was to test the possibility of monitoring and controlling in real time.
