Wastewater treatment systems are unreliable in terms of their performance. Many parameters could affect their efficiency in which load disturbances are the major cause of large perturbations in the system and the consequent deterioration in the effluent quality. It is known that the variation of the influent flow rate is more important than variations of the various components of the influent. In this paper, the effect of influent flow variation on the system has been modeled and added to the control system structure, in order to alleviate the performance problem. The control system is based on PIP/TDC methodology, which has been published in numerous papers since 1987 and also described briefly here. This kind of control system could bring some advantages to wastewater treatment systems, compared to other more well-known control systems. All experiments have been applied to an activated sludge simulation benchmark and the results show an improvement in the control performance.
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