Optimization of Collaborative Photo-Fenton Oxidation and Coagulation for the Treatment of Petroleum Refinery Wastewater with Scrap Iron

Saber, Ali; Mortazavian, Soroosh; James, David E.; Hasheminejad, Hasti

Optimization of Collaborative Photo-Fenton Oxidation and Coagulation for the Treatment of Petroleum Refinery Wastewater with Scrap Iron

2017

Saber, Ali | Mortazavian, Soroosh | James, David E. | Hasheminejad, Hasti

The photo-Fenton oxidation treatment combined with a coagulation/flocculation process was investigated for removal of chemical oxygen demand (COD) from a refractory petroleum refinery wastewater. Scrap iron shavings were used as the catalyst source. A response surface methodology (RSM) with a cubic IV optimal design was employed for optimizing the treatment process. Kinetic studies showed that the proposed process could be described by a two-stage, second-order reaction model. Experiments showed that precipitation of iron ions can be utilized as a post-oxidation coagulation stage to improve the overall treatment efficiency. More than 96.9% of the COD removal was achieved under optimal conditions, with a post-oxidation coagulation stage accounting for about 30% of the removal, thus confirming the collaborative role of oxidation and coagulation in the overall treatment. A low-velocity gradient of 8.0 s⁻¹ for a short mixing time of 10 min resulted in optimum post-oxidation coagulation. Comparison of photo-Fenton oxidation to a standard Fenton reaction in the same wastewater showed more rapid COD removal for photo-Fenton, with an initial second-order rate constant of 4.0 × 10⁻⁴ L mg⁻¹ min⁻¹ compared to the Fenton reaction’s overall second-order rate constant of 7.0 × 10⁻⁵ L mg⁻¹ min⁻¹.

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