TREATMENT OF PHARMACEUTICAL WASTEWATERS BY FENTON'S OXIDATION FOLLOWED BY ACTIVATED SLUDGE: A CASE STUDY

The objective of the study was to investigate the applicability of Fenton's oxidation for the pretreatment of the pharmaceutical effluents from a drug manufacturing facility, and to design a wastewater treatment plant to replace the existing package treatment system which failed to meet the required discharge standards. The optimal operational conditions determined in the treatability studies indicated that the treatment efficiency was best at an initial pH of 3.5 and second stage (coagulation) pH of 7. The effect of temperature on overall treatment efficiency was found to be practically negligible. For all products, average COD removal efficiency was highest when the ratio of hydrogen peroxide to ferric ions available in the system were between 150-300. At a constant H2O2/Fe+2 ratio of about 170, the minimum dosage studied; 20 L H2O2 and 0.33 kg FeSO4 per m3 pharmaceutical wastewater, provided 45% to 65% COD removal. For simplicity and ease of operation, this dosage was selected for the Fenton's oxidation unit, instead of defining different optimal dosages for each product. Monitoring of the Drogsan Wastewater Treatment Plant (DWTP), which replaced the previously operated package treatment system, showed that the efficiency of Fenton's oxidation followed by biological treatment, that is the overall treatment efficiency for Fenton's oxidation and biological treatment, is around %98 for COD removal and comply with the BOD5 limit set by the Turkish Water Pollution Control Regulation (