Reduction of wastewaters and valorisation of by-products from "Serpa" cheese manufacture using nanofiltration.

Second cheese whey (SCW) is a by-product of cheese and curd cheese production that is usually not recovered and therefore contributes substantially to the negative environmental impact of the cheese manufacture plants. Membrane technology, namely nanofiltration (NF), is used in this work for the recovery of SCW organic nutrients, resulting from "Serpa" cheese and curd production. The SCW is processed by NF to recover a rich lactose fraction in the concentrate and a process water with a high salt content in the permeate. The permeation experiments were carried out in a plate and frame NF unit, where two NF membranes (NFT50 and HR-95-PP) were characterized and tested. The NF permeation experiments were performed accordingly with two different operation modes: total recirculation and concentration. In order to select the best membrane and operating pressure for the SCW fractionation, total recirculation experiments were carried out. After the membrane selection, the concentration experiments showed that the selected membrane (NFT50) at 30 bar allows a water recovery of approximately 80%, concentrating the second cheese whey nutrients approximately 5 times. Therefore, the NF operation can successfully reduce the wastewater organic load and simultaneously contribute to the valorisation of the cheese and curd cheese manufacture by-products.