Optimization of coagulant dosage for bio-treated coking wastewater by response surface method

Abstract

Combined polyaluminum chloride（PAC）with polyacrylamide（PAM） coagulation was used to treat bio-treated coking wastewater. The influence of the dosage of PAC and PAM on the coagulation treatment effect was investigated through a single factor experiment. Based on the single factor experiment，the response surface coagulation experiment was carried out to construct the mathematical model with the dosage of PAC and PAM as independent variables and the control coefficient of residual turbidity and excess conductance of effluent as response quantity. Moreover， its parameters were optimized by response surface method. The results showed that the optimal dosage of coagulant was 2 546.96 mg/L for PAC and 10.90 mg/L for PAM. Under this condition，the average turbidity residual rate of experimental effluent was 4.24%，the conductivity excess rate was 2.77%，and the dosing control coefficient was 7.01，with a relative error <5% from the predicted value of the model.

Keywords

• bio-treated coking wastewater
• coagulation treatment
• response surface method
• polyaluminum chloride
• polyacrylamide