Water Recovery from Dairy Industry Waste Stream Whey using Forward Osmosis Technology: Evaluating the Effects of Different Draw Solutions

Whey is a fairly dilute by-product of dairy industry manufactured during production of cheese and paneer. This research intends to recover water from the whey using an emerging membrane separation technology, Forward Osmosis (FO). Different inorganic salt solutions such as magnesium chloride (MgCl2), calcium chloride (CaCl2), sodium chloride (NaCl), potassium chloride (KCl) along with sucrose and citric acid are tested as the draw solutions for maximum performance of FO. Various factors affecting FO such as Feed/Draw (F/D) ratio, temperature and concentration of different draw solution, mode and flow type of FO are varied to get the maximum output. Highest osmotic pressure solution of aq. MgCl2 shows maximum water recovery of 93% with flux of 6.84 L/m²/hr followed by aq. NaCl solution with 89.5% dewatering and flux of 5.97 L/m²/hr in Co flow RC mode of FO. Further efficiency of FO reduces in the descending order for citric acid, calcium chloride, sucrose and potassium chloride. Draw such as sucrose and NaCl can be reused in the dairy itself for various purposes eliminating the need of draw regeneration. Thus, FO successfully performs to recover water from the whey and consequently reduce the footprint on the environment.