Advanced treatment of secondary effluent of a pharmaceutical factory in northern

A combined process of coagulation with Fenton oxidation was introduced to the advanced treatment of the secondary effluent of a pharmaceutical wastewater treatment process in northern China. Major factors affecting the treatment were investigated by lab-scale tests. The results showed that FeCl₃ was the best among the tested 4 coagulants, and its optimal dose and the initial pH for reaction were 175 mg/L and 7, respectively, at ambient temperature. After the coagulation, the wastewater was treated by Fenton oxidation. An excellent treatment efficiency was obtained with H₂O₂/Fe²⁺ (M/M) of 7.5 and H₂O₂ dosage of 10 mM/L at 20°Creacting for 60 min. For the influent with a COD of 170~200 mg/L and a TP of 6~9 mg/L, a COD removal and TP removal as high as 71.5% and 99.5%, respectively, could be reached after treated by the coagulation combined with the Fenton oxidation under the optimized condition. The final effluent could meet the requirement of Discharge Standards of Water Pollutants for Pharmaceutical Industry Fermentation Products Category (GB21903-2008).