Optimisation of Fenton's reagent usage as a pre-treatment for fermentation brines

Pre-treatment of fermentation brines from green olives has been carried out by the Fe(II)/Fe(HI)/H2O2 system. Reagent concentration exerted a positive influence on chemical oxygen demand (COD) removal. Hydrogen peroxide uptake showed values in the range 0.3-1.6 mol of COD eliminated per mol of H2O2 consumed depending on operating conditions. The optimum working pH was found to be in the interval 2.0-3.5. Reaction temperature increased the COD degradation rate, although similar COD conversion values were obtained after 5 h of treatment regardless of the value of this parameter. An analysis of the biodegradability of this type of effluent demonstrated the beneficial effect of the chemical pre-oxidation. According to the experimental results, it is suggested that there is an inhibitory effect of the wastewater due to its COD content and nature rather than attributable to the presence of high amounts of sodium chloride. Biodegradation efficiency increased as temperature was raised up to 30degreesC. A further increase of this parameter up to 40degreesC resulted in the death of the microorganisms. (C) 2002 Elsevier Science B.V. All rights reserved.