Closed-loop identification and control application for dissolved oxygen concentration in a full-scale coke wastewater treatment plant

The objective of this paper is to apply a closed-loop identification to act ual dissolved oxygen control system in the coke wastewater treatment plant. It approximates the dissolved oxygen dynamics to a high order model using the integral transform method and reduces it to the first-order plus time d elay (FOPTD) or second-order plus time delay (SOPTD) for the PID controller tuning. To experiment the process identification on the real plant, a simp le set-point change of the speed of surface aerator under the closed-loop c ontrol without any mode change was used as an activation signal of the iden tification. The full-scale experimental results show a good identification performance and a good tracking ability for set-point change. As a result o f improved control performance, the fluctuation of dissolved oxygen concent ration variation has been decreased and the electric power saving has been accomplished.