Concentration of skim milk by forward osmosis using delactosed permeate as an innovative draw solution

Forward osmosis (FO) is proposed as a sustainable alternative to evaporation and reverse osmosis, but its commercial application is limited by energy-intensive draw solution recovery and solute permeation through the membrane. To mitigate this, the dairy by-product delactosed permeate has potential as a draw solution for concentration of dairy products, where permeation of solutes and draw solution recovery are not a concern. In this study, skim milk was concentrated from 9 to 18% dry matter by FO using delactosed permeate as the draw solution. The influence of temperature on filtration performance was assessed whereby average fluxes of 3.6 and 4.8 kg h⁻¹ m⁻² were obtained at 10 and 30 °C, respectively. Energy savings of ∼57% per kg of water removed compared with reverse osmosis were observed. This, together with the absence of undesirable solute permeation during FO, highlights the potential of delactosed permeate as a draw solution for concentration of dairy streams.