Integrated catalytic oxidation and biological treatment of spent caustic wastewater discharged from petrochemical industries

The integrated catalytic oxidation and biological treatment of the spent caustic wastewater (SCWW) discharged from the petrochemical industry were carried out in the present investigation. The SCWW was characterized by COD 19,246–21,054 mg/L, sulphide 4280–5092 mg/L, and phenol compounds 2349–2716 mg/L. The BOD/COD of the wastewater was around 0.196–0.216 mg/L, indicating a poor biodegradable nature. The integrated treatment scheme attempted in the present investigation comprised techniques such as catalytic functionalization oxidation reactor (CFOR), heterogeneous activated carbon Fenton catalytic oxidation (HAFCO), Fenton activated carbon catalytic oxidation (FACCO) and fluidized immobilized cell carbon oxidation (FICCO). The integrated catalytic reactors demonstrated 100% efficiency in removing sulphide, without emitting them into the atmosphere, 96.7% in removing phenol, 95.3% in removing COD and 99.2% in removing BOD. The removal of dissolved organics from SCWW by integrated oxidation process was confirmed through instrumental analysis such as UV–visible and Fourier transform infrared spectroscopy.