Adaptive continuous pH-control monitored by on-line gain identification

Abstract A method for adaptive pH-control of the waste water effluent of a chemical factory is presented. The heavy fluctuation of pH-value and the varying neutralization curve are governed by on-line identification and appropriate adjustement of the control parameters. The basic mathematical model of the stirred neutralization basin is concerned with the reaction kinetics of lime and the flow process. Some attention is given to the sulfate concentration to prevent deposition of limestone. The experiments were performed on a pilot plant for waste water treatment and show the system behaviour for step input and for randomly varying industrial waste water. The resulting smooth neutralization control yields an economic use of neutralization agents.