Membrane filtration is widely used in lactose and whey separation, particularly during whey processing after cheese production. Ultrafiltration (UF) membranes retain larger molecules such as whey proteins (β-lactoglobulin and α-lactalbumin) while allowing smaller molecules like lactose, water, and minerals to pass through as permeate. This produces whey protein concentrate (WPC) in the retentate stream. Further processing, such as nanofiltration (NF) or reverse osmosis (RO), can concentrate lactose from the permeate by removing additional water. The process is pressure-driven and non-thermal, which preserves protein functionality and improves efficiency in lactose recovery and whey protein standardization. Membrane filtration lactose separation Whey protein ultrafiltration Lactose removal in dairy Whey protein concentrate production Whey protein isolate manufacturing Dairy membrane technology Ultrafiltration in whey processing Nanofiltration lactose reduction Reverse osmosis in dairy industry Sustainable whey utilization Lactose-free dairy processing Whey fractionation technology Protein recovery from whey Dairy industry innovations