Application of an innovative membrane process as a green and sustainable management for cork wastewater

Abstract

Cork is the outer bark of cork oak tree and its main use is as a quality and natural material for wine stoppers. The cork manufacturing process involves several stages with waste generation, mainly industrial water from boiling of cork planks. Due to the toxicological properties of these effluents, they must be treated before their discharge into public courses by sophisticated treatment processes. This work studies the application of the concept of biorefinery, based in a sequential membrane process in order to achieve both: source of useful by-products and simultaneous depuration. The proposed strategy consisted of combining micro, ultra and nanofiltration to separate phenolic compounds according to their molecular weight, generating a highly purified effluent. On the other hand, a previous acid treatment was tested and the results compared. Removals of >96% for COD, >86% for TOC and nearly 100% for total phenolic compounds were achieved. Acid treatment led to a reduction of the number of membranes with similar removals but presented some disadvantages. In conclusion, the proposed valorization was successful to produce a high purified permeate stream and a set of useful by-products such as phenolic compounds, which can help to generate added value and reinforcing cork sector.

Keywords

• Cork
• Wastewater
• By-products
• Membranes
• Acid