Applicability of combined Fenton oxidation and nanofiltration to pharmaceutical wastewater

The aim of this study was to investigate the applicability of combined Fenton oxidation and membrane filtration for the treatment of a real process pharmaceutical wastewater resulting from the chemical synthesis of etodolaca pharmaceutical active compound. In single Fenton oxidation experiments, the highest process efficiencies (84% chemical oxygen demand (COD) and 95% UV254) were obtained at the H2O2/Fe2+=40 ratio. However, regarding the costs of reagents, the optimum molar ratio of H2O2/Fe2+ was selected as 20 with COD removal efficiency of 82%. Although COD could not be reduced to discharge standards, etodolac removal is fixed close to 100%. Higher flux, higher rejection rates, and lower flux decline were obtained from the combined Fenton oxidation and nanofiltration (NF) of the raw wastewater from chemical synthesis process. Although effective removals of etodolac (>99.5%) were obtained for combined and single systems, single-stage NF treatment was also insufficient for the removal of organic matter. Combined Fenton oxidation and NF treatment was found to be a promising method for wastewater from chemical synthesis processes of pharmaceutical industry containing etodolac. FT-IR spectrums showed that the calcium salts could be the main foulants on the NF membrane surface.