This study was designed to use both artificial and real textile secondary effluents to evaluate (1) the COD and color removal efficiencies for ferrous coagulation and Fenton's coagulation, and (2) the feasibility of using hydrogen peroxide to improve ferrous coagulation to meet more stringent effluent standards. The results indicate that the optimum pHs for both ferrous coagulation and Fenton's preoxidation processes range between 8.0–10 and 3.0–5.0, respectively. The rate for color removal is faster than that for COD removal in the Fenton's preoxidation process. The removals of COD and color are mainly accomplished during Fenton's preoxidation step. The ratio of COD removal for Fenton's coagulation versus ferrous coagulation, given the same ferrous dosage, ranges from 1.4 to 2.3, and it ranges from 1.1 to 1.9 for color removal, using two effluent samples. Therefore, using hydrogen peroxide can enhance the ferrous coagulation, and this ensures more stringent effluent standards of COD and color are met.
