Optimization of continuous reactor at pilot scale for olive-oil mill wastewater treatment by Fenton-like process

Reclamation of olive-oil mill wastewater (OMW) from two-phase extraction procedure was carried out in a continuous stirred tank reactor (CSTR) at a pilot plant scale by Fenton-like process. The effect of operating conditions such as pH, space-time, H2O2 and Fe(III) doses, as well as [FeCl3]/H2O2] ratio on the efficacy of Fenton's process was investigated. It is demonstrated that Fenton's process can effectively degrade organic matter in OMW. In the start-up stage, Fenton reaction reached steady state within 3 h. Oxidation of organic materials in OMW was pH dependent and the optimal pH was found to be 3. The optimum [FeCl3]/[H2O2] ratio was in the range 0.026-0.058 w/w, with Fe(III) concentration between 0.35 and 0.40 g dm(-3). The final values of COD and total phenols at the outlet of the pilot plant were close to 129 mg O-2 L-1 ([COD](initial) = 4017 mg O-2 dm(-3)), and 0.5 mg dm(-3) ([total phenols](initial) = 66.2 -mg dm(-3)), respectively. Finally, the produced water can be used for irrigation or discharged directly into the municipal wastewater system for ulterior tertiary treatment. (C) 2013 Elsevier B.V. All rights reserved.