Selective phenol removal membranes and valorization of olive oil waste streams

A process for obtaining a polyphenol rich concentrate of an olive oil mill wastewater stream, said process comprising:

• a. Contacting an olive oil mill wastewater stream with an acid, to obtain an acidified olive oil mill wastewater stream at a pH ranging from 2 to 2.5;
• b. Feeding said acidified olive oil mill wastewater stream into a holding tank, and phase separating from said olive oil mill wastewater:
• i. a bottom layer stream rich in suspended solids,
• ii. a top layer stream rich in olive oil
• iii. a middle layer stream, that is largely devoid of suspended solids and of olive oil;
• c. Feeding said middle layer stream into an ultrafiltration unit (UF), thereby separating said middle layer stream into a UF permeate and a UF concentrate;
• d. Feeding said UF permeate into a nanofiltration unit (NF), thereby separating said UF permeate into a NF concentrate rich in polyphenols and a NF permeate largely free of polyphenols;
• e. Separately feeding each of said UF concentrate and said NF concentrate into a selective side of a membrane contactor unit comprising the composite membrane of claim 1, and circulating said concentrate next to a selective side of said membrane, further whereas a high pH strip solution is circulated next to a porous side of said membrane, to obtain a polyphenol rich permeate stream at the porous side of the contactor membrane unit;
• f. passing said polyphenol rich permeate stream through a second nanofiltration unit (NF2), thereby obtaining a concentrate which is a polyphenol rich product, and a caustic solution permeate.