Processing Cheese Whey from Dairy Plants Using an Integrated System of UF-NF-RO-UV and Its Impact on Enhancing Water Quality and Economic Feasibility

This study designed and evaluated an integrated membrane filtration system consisting of ultrafiltration (UF), Nano-filtration (NF), reverse osmosis (RO), and ultraviolet (UV) treatment to process cheese whey from small and medium dairy plants and assess its technical feasibility. Three whey types—Mozzarella, Karish, and Domiati—were characterized before and after treatment. UF mainly acted as a pretreatment stage, moderately removing suspended solids and organic matter (20–50%) while maintaining stable pH. NF substantially improved water quality, achieving turbidity reductions exceeding 98% and decreasing Biochemical Oxygen Demand (BOD₅) and Chemical Oxygen Demand (COD) by up to 96%. RO delivered the highest purification efficiency, with turbidity removal greater than 99% and marked reductions in organic load; BOD₅ decreased to 150–214 mg L⁻1 and COD to 350–550 mg L⁻1 depending on whey type. Nutrients and dissolved ions were effectively rejected, with overall removal efficiencies frequently surpassing 80–97%. Complete elimination of Total plate count, total coliforms, and fecal coliforms was observed after NF and RO, confirming strong microbial retention. Organoleptic properties improved significantly, producing clear, odorless permeate suitable for reuse or environmentally safe discharge. Overall, the integrated UF–NF–RO–UV system demonstrates strong potential as a scalable and sustainable approach for whey wastewater treatment, supporting water conservation, pollution reduction, and resource recovery in dairy industries.