NONLINEAR MODEL-BASED IN-LINE CONTROL OF WASTE-WATER PH - A LABORATORY STUDY

A nonlinear model-based controller has been developed and demonstrated for in-line neutralization of acidic mixtures. The controller consist s of a simple, steady-state, three-parameter, nonlinear phenomenologic al model which mimics a wide range of titration curves from strong aci d to highly buffered systems. The model is parameterized from an-line process data whenever nearly steady-state conditions are statistically identified. Results show excellent control performance in the presenc e of both ramp and step changes in acid type, acid concentration and f low rate upsets.