The identification and robust control of a biological wastewater treatment process

This paper deals with the identification and robust control of a biological wastewater treatment process. The identification has been done on the basis of the minimization of an Euclidian-distance criterion, with respect to the model coefficients. The robust control of the biological wastewater treatment process has been accomplished through QFT (quantitative feedback theory) techniques. To this end three functioning points were defined: big_flow, small_flow and medium_flow. The process has been linearized in the three functioning points. For every linear model a robust controller was designed using QFT robust designing techniques. The overall controller has the same structure with the controllers obtained before. Its parameters are determined by fuzzy aggregation the parameters of the three controllers. The parameter aggregation takes into account the membership degree of the current functioning point to the one or maximum two functioning points defined before.