AbstractIn feedforward control systems, the output is made equal to the set point by measuring the disturbances in the input signal. This is in contrast to the common feedback control system where the error in the output is used to control the input to the system in order to get the output close to the set point. In practice, feedforward control is used in conjunction with feedback contro1.Feedforward control is generally used in systems with large time delays. This is the case with biochemical reactors used in Waste water treatment. It is desired to study a model of this system. Luyben (1) has done a similar study of reactors for the case of second order reactions.