Examination Of Methods To Reduce Membrane Fouling During Dairy Microfiltration And Ultrafiltration
Pressure-driven membrane filtration processes such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) provide opportunities for the dairy industry to better utilize milk by separating its components based on size. However, widespread adoption of some of these processes has yet to be realized due to membrane fouling. Membrane fouling is the accumulation of soil, or foulant, on the surface or within the pores of a membrane. Fouling prolongs processing times, increases energy and cleaning costs, decreases separation efficiency, and, in severe cases, may lead to irreversible clogging of the membrane. Microfiltration can be used to remove serum proteins (SP) from skim milk. The process' SP removal efficiency directly influences the technology's financial feasibility. Our first objective was to quantify the capacity of 0.14 [MICRO SIGN]m ceramic Isoflux MF membranes to remove SP from skim milk. The Isoflux membranes' manufacturer claims that using these membranes will reduce localized membrane fouling at the inlet end of the membrane that results from using high cross-flow velocities (5 - 7 m/s) to mitigate overall membrane fouling. Contrary to theoretical cumulative SP removal percentages of 68%, 90%, and 97% after 1, 2, and 3 stages of 3X MF processing, respectively, the 3X Isoflux process removed only 39.5%, 58.4%, and 70.2% after 1, 2, and 3 stages, respectively. Several design aspects of the membrane are thought to have resulted in this inefficiency. Ultrafiltration can be used to concentrate SP and reduce the lactose content of cheese whey or MF permeate of skim milk to produce 80% whey protein concentrates (WPC80) or 80% serum protein concentrates (SPC80), respectively. The objectives of our second study were to determine if adding annatto color to milk or bleaching whey or MF permeate of skim milk with hydrogen peroxide (H2O2) or benzoyl peroxide (BPO) influenced UF flux, diafiltration flux, or membrane fouling during production of WPC80 or SPC80. Addition of annatto color to milk had no effect on flux or fouling. Bleaching with or without added color increased flux during processing. Bleaching with H2O2 produced higher flux than bleaching with BPO. While bleaching with BPO reduced membrane fouling during WPC80 production, it did not impact membrane fouling during SPC80 production. Bleaching with H2O2 led to the largest reduction in fouling for both production processes.
Dairy; Filtration; Membrane Fouling
Barbano, David Mark
Hooker, Giles J.
Food Science & Technology
M.S. of Food Science & Technology
Master of Science
dissertation or thesis