Recovery of phenolic antioxidants and water from olive mill wastewaters by integrated membrane processes

Olive mill wastewaters (OMWs) produced by the oil extraction industry represent a serious environmental problem because of theri high organic load and also phenolic substances with low biodegradability. However, they have received a great attention in the last years for the presence of high added value compounds such antioxidant substances and polyphenols, which can be used in pharmaceutical, nourishment and cosmetic applications. This study aims to evaluate the potentiality of an integrated membrane system in the treatment of OMWs to produce a purified fraction enriched in low molecular weight polyphenols, a concentrated fraction of organic substances and a water stream which can be reused in the extractive process of olive oil. In particular, a sequence of two ultrafiltration (UF) processes followed by a final nanofiltration (NF) step was investigated on laboratory scale operating in selected process parameters. The produced fractions were analyzed for their total content of polyphenols, total antioxidant activity (TAA), free low molecular weight polyphenols and total organic carbon (TOC).