Polymeric Membranes for Lactose Recovery and Dairy Wastewater Treatment: Effect on Sustainability and Circular Economy

ABSTRACT The dairy industry is one of the most important agro‐industrial sectors worldwide, with products produced from this industry including milk, yogurt, cheese, butter, and ice cream. The large volume of wastewater generated by the industry has to be treated before it can be discharged. This can be done in several ways, including contaminant reduction through flocculation and depth filtration. These traditional treatment methods, however, are not very effective. In this work, an alternative method was developed to improve the environmental sustainability of the dairy industry and its effect on sustainability and the water–food–energy nexus. This was achieved by using polymeric membranes. The technical feasibility of separation of lactose–whey protein from the wastewater and of water recovery using integrated membrane technologies was examined. This study focused on an ultrafiltration (UF)/reverse osmosis (RO) hybrid system in a laboratory‐scale experiment to measure milk whey component removal performance. Enhanced results for lactose–whey protein rejection were achieved by coupling modified UF and RO membranes. Modified UF membranes, composed of PVC/NMP/PEG with antifouling nanoparticles of TiO 2 and ZnO as additives, showed high fouling resistance as flux recovery ratio together with reversible and irreversible fouling to have FRR of 97% and 9% for reversible fouling 3% and irreversible fouling compared to the commercial UF membrane with higher percentages. Scanning electron microscopy (SEM) morphology showing the surface and different layers of the membranes was used to characterize UF and RO membranes. Modified UF membranes showed a significant improvement in the percentage of mixed dairy wastewater rejection reaching 96%. The approach demonstrated major advancement in resource recovery for a valuable by‐product, lactose, using a scalable low‐cost UF membrane and demonstrated that multistage UF membranes may be used without RO and operated at low pressure as a cost‐effective technological package.