engleski

CHEMICAL CHARACTERIZATION OF OLIVE OIL MILL WASTE MATRIX AND SUBFRACTION: SPECIES SPECIFIC TOXICITY STUDY

The production of olive oil yields a considerable amount of olive mill wastewater (OMW) as a by-product of olive oil extraction process, which is currently discarded throughout the Mediterranean region. It is estimated that 7x106 – 3x107 m3 of OMW is generated annually, which is alarming considering that this type of pollution is equivalent to the pollution of municipal wastewater produced by 20-22 million people. OMWs significant polluting properties are mainly related to high organic load, increased COD/BOD ratio, high phenolic content and relatively acidic pH. Currently, there is no strict regulation or appropriate method applied for treating OMW. It is usually discharged into sewage systems and/or into different environmental compartments. There is no data concerning the level of OMW in the receiving waters, but considering that the approximated amount of 1.5 million tons of untreated OMWs are annually disposed in a short period, it is obvious that OMW are becoming a potential environmental issue. Previous toxicity evaluation of OMWs were mostly based on one-way research, which contributed to the lack of studies using a battery of ecotoxicological assays with model organisms from different trophic levels and with different sensitivities. The main goal of this study was to evaluate (sub)lethal effects of OMW to different model organisms: Vibrio fischeri, Chlorella vulgaris, Dapnia magna, Danio rerio, Trifolium repens and Triticum aestivum. Identical bioassays were performed with raw sample and subfraction in order to determine in which amount polyphenols are responsible for the OMWs toxicity. Moreover, analysis of organic compounds within the subfraction was carried out using gas chromatography–mass spectrometry and high resolution mass spectrometry. Obtained results identified tyrosol as the most common polyphenol, and showed a clear correlation between polyphenols concentration and observed toxicity. These findings may contribute to the understanding of OMW induced toxicity on primary producers (plants, invertebrates and vertebrates) and its potential environmental effects.

olive mill wastewater ; toxicity ; model organisms ; GC-MS ; tyrosol

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