Optimization of coagulants in the treatment of polluted water with low temperature and turbidity

The performances of aluminum sulfate, ferric chloride and poly aluminum chloride in the removal of turbidity and organic substance are compared by jar test, and the optimum pH of coagulation is also studied. The results indicate that in the case of Songhuajiang water with low temperature and turbidity, the coagulation of aluminum sulfate in combination with activated silica is better than that of ferric chloride or poly aluminum chloride. The optimum pH for coagulation is 6.0～7.0. Under optimal coagulating conditions, coagulation with ferric chloride is the best. It can also be seen that it's efficient to evaluate and choose coagulants with respect to turbidity and organic substance removal for increasing pollutant removal efficiency in coagulation and sedimentation.