Abstract:Compound coagulant polyaluminium chloride(PAC) and bentonite is used to dispose the high turbidity steel wastewater, and with the removal rate of turbidity, CODCr as the index, the related factors are determined, such as the dosing sequence, the pH value, the dosage, the temperature, the stirring rate, the stirring time, the raw water turbidity, and appropriate process conditions. Through a large number of trials, the results show that in the appropriate condition, the pH value is 12, the stirring intensity is 200r/min, for 20min, the dosing sequence is first bentonite and then PAC, bentonite and PAC dosages are 150 and 5mg/L, respectively, raw water CODCr between 180 and 220mg/L, turbidity range is 9250~9480NTU, the removal rate of turbidity, CODCr, can reach 80% and 99.9%, respectively. The treatment effect with the compounded coagulant is better than bentonite and PAC being used alone, and compared with other treatment methods, this treatment has a good economical efficiency and provides a new treatment for the steel wastewater.