Forward Osmosis: An Energy-Efficient Approach for the Treatment and Recovery of Resources from the Dairy Industry Effluent

Abstract

The study explores implementing the Forward Osmosis (FO) membrane separation process to recover resources from whey, a waste stream in the dairy industry. A Hollow Fibre FO (HF-FO) membrane with membrane area of 13.8 m2 was employed, using aqueous NaCl as the draw solution. The optimization study delves into the impact of operating parameters such as mode of FO, concentration and osmotic pressure of draw solution and Transmembrane Pressure (TMP) on overall process efficiency. In the recirculation mode of FO, 24% (w/w) aqueous NaCl draw solution attained an impressive water recovery of 83.06% at a flux of 2.206 LMH (liters per square meter per hour) without any external TMP. With a slight application of TMP of 0.35 bar, water recovery further increased to 94.41%, concurrently achieving a high concentration factor of 17.87 at a flux of 2.462 LMH. Notably, lactose, a value-added product, is concentrated from 3.95% to 49.5% in the concentrated whey stream. The reported FO process exhibited remarkable energy efficiency, achieving a specific energy consumption of less than 8 kWh per ton of water removed. Thus, this approach is resourcefully and economically beneficial for the dairy industry, presenting a sustainable solution with positive environmental implications.