Membrane fouling in whey processing and subsequent cleaning with ultrasounds for a more sustainable process

Cost reduction and minimization of environmental impacts, based on by-product recovery, is the objective of applying the ultrafiltration technology for the treatment of cheese whey. In this work, ultrafiltration process was studied in an integrated way (filtration and membrane cleaning), focusing especially on the membrane cleaning. Membrane cleaning experiments were carried out with and without ultrasounds to evaluate the effect of ultrasounds on the membrane cleaning efficiency and, as a result, to reduce the consumption of chemicals. Tests were performed with two ultrafiltration polymeric membranes with molecular weight cut-offs of 30,000 Da (UH030) and 5000 Da (UP005). Fouling experiments were carried out with Renylat whey protein concentrate solutions and CaCl2 addition at a transmembrane pressure of 2 bar and cross flow velocity of 2 m/s during 2 h. Results showed that the presence of calcium increased the membrane fouling of both membranes. For UH030 membrane the reversible fouling prevailed over the irreversible fouling, meanwhile for UP005 membrane the irreversible fouling was the predominant one. Cleaning efficiency results demonstrated that ultrasounds application is an effective technique to clean ultrafiltration membranes after being fouled with whey protein concentrate solutions and may have a paramount importance on the overall process efficiency.