Humic like substances extracted from oil mill wastes in photo-Fenton processes: Characterization, performance and toxicity assesment

Olive mill waste has been used as sourcing materials for the isolation of humic like substances (OMW-HLS) which have demonstrated its capacity to expand the range of applicability of photo-Fenton process to pH= 5. During the isolation process, membranes of three different pore sizes (300 kDa, 150 kDa and 50 kDa) were employed in order to obtain three batches of OMW-HLS. Four pollutants contained in 2013/39/EC were used as target substances: terbutryn (TBT), diclofenac (DCF), chlorfenvinphos (CVF) and pentachlorophenol (PCP). Results showed that OMW-HLS was able to enhance photo-Fenton at pH = 5, but differences were not significant, either among fractions or with commercial humic substances. Reactions were scaled-up and driven under real sunlight and pollutants removal was faster in the presence of OMW-HLS. Toxicity was monitored according to bioassays based on different organisms or cell lines. Detoxification was observed with and without OMW-HLS, although higher toxicity was detected in the presence of humic acids, most probably due to the surfactant effect, that allows a better contact between pollutant and organism.