Combined Treatment of Pharmaceutical Effluents from Medical Ointment Production

摘要

Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H2O2/COD weight ratio of 2:1, H2O2/Fe~(2+) molar ratio of 10:1 and two hours of treatment time. The fast pH decrease to acidic values ～3 during first minutes of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of ferric iron precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD7 reduction and BOD7/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent ferric iron/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improved the biodegradability of pharmaceutical effluents.