engleski

Assessment of Toxicity Potential of Raw Olive Mill Wastewater and Polar Subfraction using Set of Bioassays

Olive processing is one of the fastest growing agro-food sectors in EU with more than 4% of annual growth rate [1]. Although very important for the economy of the Mediterranean region, olive processing has been recognized as one of the most problematic in terms of environmental pollution, which is evident from the fact that next to the olive oil (only 20 % of the input volume), two waste matrices known as pomace (30 %) and wastewater (50 %) are also produced. Released into environment they can within a short period cause irrecoverable impact to the environment and environmental organisms. Although olive processing lasts only three months, 10-30 m3 of olive mill wastewater (OMW) is produced annually, which is equal with pollution of municipal wastewater that is produced by 20-22 million people [2]. Though there is an unquestionable need for monitoring, there are still no data concerning the level of OMW in the receiving water, and there are no established protocols in order to accurately assess the toxic potential of OMW. Previous studies already reported negative impact of raw OMW on microorganism, marine and freshwater organisms and plants [2, 3], but all those results are difficult to compare due to the different exposure times, concentrations and selected endpoints, and also does not tell much about toxic potential of polyphenols contained in those OMW samples. For this reason, within our research solid phase, extraction was preformed and concentration of polyphenols were determined using HPLC-UV. Four toxicity tests which covered different modes of action were conducted for the evaluation of the environmental impact of unfractionated OMW sample, and also polar subfraction: i) algal growth inhibition test using Chlorella vulgaris [4] ; ii) germination seed test with two plants – Trifolium repens and Hordeum vulgare ; iii) Daphnia sp. acute immobilization test [5] ; iv) zebrafish embryotoxicity test [6]. All experiments were performed on undiluted (100 %) and diluted raw OMW/polar subfraction samples (1, 5, 10, 25, 50 and 75 %). Obtained results showed a clear correlation between polyphenols concentration and observed toxicity. Those findings may contribute to the understanding of OMW induced toxic effects on primary producers, plants, invertebrates and vertebrates.

Olive oil mill wastewater ; Bioassays ; Model organisms ; Toxicity

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