Design and optimization of a sequential and hybrid advanced oxidation process system using response surface methodology

Of different approaches for refinery effluent treatment, the application of Advanced Oxidation Processes (AOPs) (e.g. electro-Fenton) and nano Zero-Valent Iron (nZVI) particles have been of great interest lately. Associated constraints with these methods inspired the design of a sequential hybrid system by which higher treatment efficiency and less energy consumption were acquired compared to a conventional system. The hybrid system consisted of an electro-Fenton and an nZVI slurry system working in sequence. Both sub-systems were first optimized using the Response Surface Methodology (RSM), and the hybrid system was then designed accordingly. 94.06% of COD removal was achieved by the hybrid system in only 47.5 min at its optimum condition (CODinitial = 500 mg/L, [nZVI] = 0.9 g/L, and H2O2/Fe2+ = 3.6). Whereas it took more than 75 min for the single electro-Fenton system to acquire similar efficiency. GC–MS analysis also supported the superiority of the hybrid system over the conventional one.