Comparison of Physicochemical Characteristics and Bioactivity of Olive Oil Mill Wastewaters from Traditional and Water-Saving ARA-Controlled Three-Phase Decanter

Olive mill wastewater (OMW) is one of the most environmentally concerning food processing effluents due to its phytotoxicity. Recently, several bioactive compounds with potential applications in food, pharmaceutical, and agricultural industries have been identified in OMW. This study aimed to compare, for the first time, the physico-chemical characteristics and biological activity of OMW obtained by two different types of three-phase decanters: a traditional one and a water-saving ARA decanter. DPPH, ABTS, FRAP, and β-carotene bleaching tests were used to investigate the antioxidant effects. The inhibition of key enzymes involved in hyperglycemia and hypolipidemia were also assessed. A high concentration of phenolic compounds was found in OMW obtained by the ARA-controlled system. Hydroxytyrosol resulted as the dominant compound, with a content of 502.3 mg/kg. OMW extract obtained by ARA decanter resulted as the most active in the FRAP test, with value of 67.23 µMFe (II)/g. A moderate inhibitory activity was found against α-amylase, α-glucosidase, and lipase enzymes. Data obtained by this study evidenced that the use of the ARA decanter allows for obtaining OMW extract characterized by a higher content of phytochemicals in comparison to those obtained by the traditional phase decanter, and a consequent higher biological activity. At the same time, the use of this equipment allows for the reduction of environment impact.