Dewatering of Sweet Whey Using Forward Osmosis on an Industrial Scale

Industrial whey dewatering via membrane processes remains challenging due to the rapid increase in viscosity, strong fouling tendencies from proteins and minerals, and the steep rise in osmotic pressure during concentration. These effects restrict operating windows and complicate energy-efficient process control. This study addresses the application of forward osmosis (FO) technology for industrial-scale dewatering of sweet whey using an Aquaporin Inside® HFFO14 module. Various feed- and draw-side cross flow velocities (0.0397 to 0.0524 m s−1 and 0.0127 to 0.0190 m s−1, respectively) and draw solution (DS) osmotic pressures of 20 bar and 60 bar were investigated using a production-scale prototype plant. Sweet whey had an initial osmotic pressure of 7 bar and an electrical conductivity of 5.7 mS cm−1. DS pressures of 20 bar and 60 bar resulted in a total recovery of 50% and over 80%, respectively. Water flux rates initially ranged from 10.1 to 11.6 L m−2 h−1 (LMH) and ceased at 3.3 LMH. Specific energy demand ranged from 0.15 to 1.1 kWh m−3. These findings support the feasibility of industrial-scale FO technology and underscore the potential of FO as an energy-efficient, sustainable solution for the dairy industry. However, frequent rinsing and cleaning routines are crucial to maintain membrane performance.