Advanced treatment of petrochemical secondary effluent by Fenton: performance and organics removal characteristics

The Fenton process was used to treat petrochemical secondary effluent. The effects of initial pH, H₂O₂, and FeSO₄·7H₂O dosages on chemical oxygen demand (COD) removal, the dissolved organic matter (DOM) removal and the transformation and migration of typical organic matters during the treatment process were investigated. The results showed that the optimum conditions were initial pH of 3.0, H₂O₂ (30%) dosage of 0.4 mL/L, and FeSO₄·7H₂O dosage of 1.0 g/L. The highest COD removal efficiency of 61.9% could be achieved for this condition when the average influent COD was 78.5 mg/L. Most of the DOM in the petrochemical wastewater could be removed effectively by Fenton through direct oxidation and coagulation. For example, for trans-1,2-dichlorocyclopentane, results showed that 56.3% of it could be removed by Fenton oxidation, while 13.3% of it could be absorbed by the in situ generated Fenton chemical sludge. The Fenton process is simple and it is suitable for the advanced treatment of petrochemical secondary effluent.