Monitoring of the quality of winery influents/effluents and polishing of partially treated winery flows by homogeneous Fe(II) photo-oxidation

Winery wastewaters contain high concentrations of organic compounds including phytotoxic and recalcitrant compounds like phenols. Its treatment by conventional processes is difficult due to the variability of the characteristics of the liquid waste. The main objectives of this work were to (I) monitor onsite the quality of winery wastes prior to and following sequential physical and biological treatment and (2) assess the efficiency of coupling physical and biological treatment to photo-Fenton oxidation serving as the final polishing step. A partially treated effluent with chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) values of 1060 and 210 mg/L respectively was subject to photo-Fenton oxidation at H2O2 and Fe2+ concentrations between 34-175 and 0.5-2 mM respectively, solution pH(0) = 2.5, under continuous UV-A irradiation provided by a 125 W lamp. In general, organic matter degradation increased with increasing treatment time reaching values of COD or BOD removal as high as 80% after 4 h of reaction. Regarding the effect of initial iron and hydrogen peroxide concentrations, there appears to be an optimum dosage for both, above which treatment performance deteriorated. Hence, the combined biological + photo-Fenton oxidation resulted in 95% COD removal.