Automatic Dosing Control for Coal-containing Wastewater Based on Turbidity Feedback and Metering-pump Feedforward Compensation

A field-data-constrained automatic dosing method is developed for coal-containing wastewater with a sedimentation volume of approximately 400 m3, a nominal recycle flow of 50 m3/h, and baseline PAC and PAM dosages of 0.4 and 0.01 g/L. An equivalent treatment-age model is constructed from nine discrete turbidity samples. Flow-based dosage feedforward, segmented logarithmic turbidity feedback, anti-windup, and an inverse metering-pump model are combined. In the parameterized average-inflow case, the proposed method reaches 5 NTU at 5.42 h and consumes 151.74 kg of effective chemicals, 7.48% below fixed dosing. The pump-flow tracking RMSE decreases from 1.00 to 0.09 L/h relative to the controller without inverse compensation. The six-hour compliance rate is 89.17% in 240 parameterized robustness runs. These results support pre-commissioning parameter checks and do not constitute field closed-loop validation.