INFLUENCE OF OXIDATION PRE-TREATMENT ON ANAEROBIC DIGESTION OF OLIVE MILL WASTEWATER

Detoxification and degradation of olive mill wastewater (OMW) by the fenton process along with chemical coagulation and precipitation was investigated. Experiments were conducted to investigate the effects of operating variables, including pH, temperature, initial concentrations of Fe ++ and H2O2 and treatment time, on the COD and total phenolic compounds (TPC) removal efficiency. Optimal operating conditions were experimentally determined. Chemical coagulation using lime and polyamide as coagulant and flocculant respectively was found to complement the fenton treatment process in reducing the floc settling time, enhancing color removal and reducing Fe ion concentration. The detoxification rate of OMW, after fenton process application, was evaluated from the improvement of the efficiency of a following anaerobic biological treatment process. For 2 g/l of initial addition of FeSO4 7H2O, for 6 ml/l of initial addition of H 2O2 (60%), for pH=3 for temperature 20oC and for oxidation period of two hours the COD reduction was about 70% and the TPC reduction was almost 100% as well as the improvement of anaerobic sludge activity was increased from 0.01 to 1.47 g CODr /g of VSS - day. The results indicate that the oxidation of OMW using fenton process following by an anaerobic digestion is an effective and feasible method of treatment.