PREFILTRATION OF COTTAGE CHEESE WHEY TO REDUCE FOULING OF ULTRAFILTRATION MEMBRANES

To improve membrane performance and extend the interval between cleanings, a two‐step ultrafiltration process is proposed consisting of prefiltration with an open‐pored membrane followed by normal ultrafiltration. Three to fourfold increases in permeation rate were observed in laboratory‐scale experiments when whey was prefiltered through ultrafiltration membranes of graded porosity to remove microorganisms and protein complexes. It is postulated that fouling occurs when the larger whey constituents settle on the membrane in a lattice network which fills in and is coated over with smaller, sheet‐forming whey proteins such as β‐lactoglobulin. Fouling substances were studied with scanning electron microscopy and identified by sodium dodecyl sulfate gel electrophoresis.