Identification of biological parameters for monitoring the quality of olive oil mill waste waters after purification and recovery of bioactive compounds

Olive oil mill waste waters (OMWWs), a polluting byproduct of the olive oil production process, contain large amount of organics and inorganics compounds (polyphenols, salts, etc) that, if inappropriately discharged, can cause environmental pollution. Polyphenols have several biological activity, but at high concentration they are toxic and their removal from OMWW is an important matter. In this work the detoxification of OMWW, performed by membrane filtration systems, was investigated with the dual aims, of reducing the organic load of OMWW and recovering polyphenols. The OMWWs were processed by ceramic and polymeric membranes with different porosity, to obtain three fractions: microfiltrate (MF, 100,000 Da), ultrafiltrate (UF, 5000 Da) and nanofiltrate (NF, 200 Da). The fractions were characterized by HPLC analysis, to quantify the main polyphenols present: Hydroxytyrosol, Tyrosol, Caffeic and Coumaric Acids, Verbascoside, Isoverbascoside, Secologanoside, and Comselogoside. MF and UF fractions exhibited antimicrobial activity against Escherichia coli, as well as against Pseudomonas aeruguinosa and Staphylococcus aureus pathogen strains. No activity was given by NF fraction. Thus, MF and UF might be considered as natural antibiotics, taking into account mainly their effect in inhibiting the growth of E. coli and S. aureus. Phytotoxic and genotoxic effects were analysed in Vicia faba L. plants germinated in MF, UF and NF fractions. The major phytotoxic effects were shown in seeds germinated in MF fraction. Genotoxicity analysis relied on mitotic activity (MI), aberration index (AI) and micronucleus frequency (MCN): MI was generally reduced, cytogenetic aberrations were found in all the treatments and MCN were mostly present in MF fraction. Results generally indicated the efficiency in polyphenols recovery and natural antibiotic activity of MF and UF fractions. Genotoxicity and phytotoxicity effects of filtrated OMWWs suggested the need of further treatments/ dilutions before their discharge in the environment.