Feedback-feedforward control of a sewer

This paper deals with the design of a feedback-feedforward controller for a sewer. The objective is to reduce the concentration of macromolecules (typically proteins, lipids and polysaccharides) entering the wastewater plant via the addition of a consortium of enzymes and bacteria in the sewer connecting houses to the plant. The hydrodynamics of the sewer are basically plug flow ones. An experimental set-up has been built in order to simulate the behaviour of the sewer at laboratory scale. The design of the controller is based on a simplified model of the sewer consisting of a CSTR model plus a time delay. The controller includes feedforward action in order to reduce the influence of the periodical variation of the influent pollutants. The controller performance is illustrated in numerical simulation.