A Comparison of Several Control Algorithms for Activated Sludge Waste Rate

Computer simulation was used to compare several algorithms (representing static control, feedback control, and feedforward control) for controlling the rate of waste in the activated sludge process. The effect of each algorithm on variability in sludge age, biomass, and F/M ratio was evaluated. Until the relationship between these parameters and effluent quality was better understood, a conservative control strategy should be adopted: plants that wasted mixed liquor should use constant flow wasting, and those that wasted return sludge should use constant proportion wasting.