LAUSR

Abstract Large volume of untreated olive oil mill wastewater (OMW) is being stored in evaporation rafts. Given the high organic load and the presence of phenolic compounds in OMW, an effective treatment process should be implemented. In this work, an advanced oxidation process (photo-Fenton) operating in a batch reactor was used to treat OMW. All experiments were developed using FeCl 3 as a catalyst. Different H 2 O 2 concentrations (5.0, 8.0, 11.0, 15.0, 16.0, 21.0, 24.0 and 30.0 g/L) were studied as well as four commercial medium pressure UV-lamps (Standard, Z1, Z2 and Z3). The common operation conditions were: pH = 3, temperature 20 °C, [catalyst] = 3.0 g/L and direct ultraviolet light (UV-light). The samples were analysed at different times during the experiments to determine water quality parameters. In general, high total carbon, total organic carbon, total phenolic compounds and turbidity removal percentages (>90%) were registered in all experiments, at all oxidant concentrations studied. Increasing oxidant concentrations did not imply a noticeable rise on the final removal percentages (approximately 5% at these experimental conditions). Total nitrogen content removal percentages were determined and varied in the range of 62.5–75.5%. UV-lamps presented virtually similar removal percentages with the following averages COD = 95.7 ± 0.53%, total phenolic compounds = 93.6 ± 2.5%, total carbon = 94.0 ± 1.2%, total organic carbon = 96.3 ± 0.6%, total nitrogen = 74.9 ± 6.8% and turbidity 92.5 ± 1.9%.