Evaluation of COD and color removals of effluents from UASB reactor treating olive oil mill wastewater by Fenton process

The study aims to depurate olive oil mill wastewater (OMW) by combining a primary anaerobic treatment and Fenton process. A laboratory scale anaerobic digestion was operated in an up flow anaerobic sludge blanket (UASB) reactor for 30?days under mesophilic (36.5 ? 37?C) conditions at organic loading rates (OLR) of 1 kg COD m(?3)d(?1) with HRT of 10?days. During steady-state operation, the anaerobic reactor achieved a 76.8% COD removal. The anaerobic treatment effluent was further treated through the Fenton treatment process using Fe2+ and H2O2. Laboratory scale investigations were performed on the anaerobically treated OMW effluents so as to decide the optimum working conditions (initial pH, dose of Fe2+ and H2O2). Fenton treatment achieved COD and color removals of 91% and 96% at the optimized conditions, respectively. The predicted optimum parameters for the Fenton process were the dosages of 40 mgL(?1) Fe2+ and 250?mgL(?1) H2O2 demonstrated that optimum operation pH was 3.0 for COD and color removal from the anaerobically treated OMW. In order to remove 1?g of COD from anaerobically treated OMW has been enough 19 mg of Fe2+ and 118 mg of H2O2. Combining anaerobic treatment with secondary Fenton process clearly show that about 98% of COD of 1/8 diluted raw OMW could be successfully treated. The operating costs of the Fenton process optimum condition were also evaluated in this study.