Secondary raw materials from agroindustrial by-products and waste from nanofiltration

Abstract

The adoption of a new economic model, the Circular Economy, that promotes closing the loop of products life cycles based on greater recycling and reuse, is driving attention to by-products and waste valorisation. Food production chain is considered one of the main waste producers. Therefore, several studies on its by-products and waste valorization have been carried out, producing a wide range of secondary raw materials. Membrane technologies are increasingly used for the recovery of valuable compounds such as fibers, pectin, sugars, proteinsand phenolic compounds from agroindustrial waste. In Mediterranean countries olive oil, wine and cheese production chains are of special interest, having an important economic and social impact in these countries, often associated with the production of high quality products, such as the PDO (Protected Designation of Origin) olive oils and cheeses and the VQPRD (Quality Wines Produced in Demarcated Wine Region) wines. The current chapter gives an overview regarding nanofiltration (NF) application for recovering high added-value compounds from the above mentioned agroindustrial by-products and waste streams. For example, in cheese making production, NF has been recently used to recover the components of cheese whey ultrafiltration (UF) permeates of a molecular weight lower than 1000 Da, aiming for its selective separation, concentration and/or demineralization, with advantages over other techniques. Compared with reverse osmosis it enables an energy saving of 20 to 45%, due to the use of lower transmembrane pressures. NF technology has also been lately examined to recover valuable antioxidant compounds from the wastes of olive oil industry, particularly low-molecular-weight polyphenolic compounds from olive mill wastewater. To sum up, NF is a technology that, if properly optimized, can offer a series of advantages in contrast to classic separation processes for the recovery of highly valuable components from the waste streams of these industries, core of the agro-industrial sector.