No abstract

In this paper, Fenton process was determined to be an effective technique to treat the refractory nonylphenol ethoxylates (NPEOs) wastewater. The chemical oxygen demand (COD) removal efficiencies above 89% were obtained when the initial COD concentration was 12,000 mg/L. However, a large amount of ferric sludge (SS = 8.724 g/L) would be produced after the Fenton oxidation of the wastewater and must be disposed appropriately. A novel process for Fenton sludge reused by low-cost ferrous sulfide (FeS) was also investigated. Experimental results show that the Fenton sludge could be reduced to produce a certain amount of Fe 2+ in the acidic mixed liquor byFeS. This mixed liquor from Fenton sludge could be used as the new catalyst in the Fenton process and was also highly effective for the NPEOs wastewater treatment. The residual FeS from the mixed liquor could be used for the next batch of the reaction.

The Fenton oxidation process was applied in the treatment of an actual high concentration nonylphenol Ethoxylates (NPEOs) wastewater. The effects of H 2 O 2 dosage, molar ratio of H 2 O 2 /Fe 2+ (Fe 2+ dosage), pH value and reaction time on the degradation of NPEOs were investigated. The orthogonal experiment indicated that the order of degree of influence on the COD removal was molar ratio of H 2 O 2 /Fe 2+ , reaction time, dosage of H 2 O 2 , and initial pH. The single-factor tests were carried out to determine the optimal conditions, and the results were H 2 O 2 dosage of 76.32 mmol/L, molar ratio of H 2 O 2 /Fe 2+ of 3, pH value of 5 and reaction time of 2 h. Under the optimum operation conditions, the COD removal efficiency was 85.6% and the effluent could be mixed with other wastewater into the large-scale biological treatment system.