Two‐Level Multivariable Control System of Dissolved Oxygen Tracking and Aeration System for Activated Sludge Processes

Abstract

The problem of tracking dissolved oxygen is one of the most complex and fundamental issues related to biological processes. The dissolved oxygen level in aerobic tanks has a significant influence on the behavior and activity of microorganisms. Aerated tanks are supplied with air from an aeration system (blowers, pipes, throttling valves, and diffusers). It is a complex, dynamic system governed by nonlinear hybrid dynamics. Control of the aeration system is also difficult in terms of control of the dissolved oxygen. In this article, a two-level multivariable control system for tracking dissolved oxygen and controlling an aeration system is designed. A nonlinear model predictive control algorithm was applied to design controllers for each level. This overall hierarchical control system was validated by simulation based on real data records provided by a water resource recovery facility located in Kartuzy, Northern Poland. The effect of control system parameters and disturbances was also investigated. Water Environ. Res., 87, 3 (2015).

Comparison of Two Nonlinear Predictive Control Algorithms for Dissolved Oxygen Tracking Problem at WWTP

“…In summary, the aim of the paper is the design of the hybrid nonlinear control system to perform an efficient control quality of DO concentration for different operating conditions. This paper further develops the results presented in [16,15]. Two advanced hierarchical nonlinear predictive control systems are designed and compared.…”

“…In [15] a nonlinear multivariable hierarchical MPC was applied to design the ULC. This controller extends to plants with several aerobic zones supplied by an aeration system of limited capacity.…”

“…Only DO and airflow measurements are applied for control systems design. In this paper, as opposite for previous research works [16,15] dynamic of aeration system is omitted and treated as a static system, which provides the amount of air required by the control system. Simulation tests for case study plant are presented.…”

A Model-Based Improved Control of Dissolved Oxygen Concentration in Sequencing Wastewater Batch Reactor

“…This approach was applied in modelling others plants, e.g. [5,6,7]. Model of the Swarzewo aeration system was first presented in [15].…”

“…predictive controller [3,4,5,6,7], multivariable PID controller [8,9], neural and fuzzy controllers [10,11]. Other DO control strategies using NH4, NO3 and PO4 measurements have been designed and tested, e.g.…”