title: Microfiltration: Effect of channel diameter on limiting flux and serum protein removal.
abstract: Our objective was to determine the limiting flux and serum protein (SP) removal at 8, 9 and 10% true protein (TP) in the retentate recirculation loop using 0.1-µm ceramic graded permeability (GP) microfiltration (MF) membranes with 3mm channel diameters (CD). An additional objective was to compare the limiting flux and SP removal between 0.1-µm ceramic GP membranes with 3mm CD and previous research using 4-mm CD membranes. The MF system was operated at 50°C, using a diluted milk protein concentrate with 85% protein on a total solids basis (MPC85) as the MF feed. The limiting flux for the MF of diluted MPC85 was determined at 8, 9, and 10% TP concentration in the recirculation loop. The experiment using the 3-mm CD membranes was replicated 3 times for a total of 9 runs. On the morning of each run MPC85 was diluted with reverse osmosis water to a MF feed TP concentration of 5.4%. In all runs the starting flux was 55 kg/m2 per hour, the flux was then increased in steps until the limiting flux was reached. For the 3-mm CD membranes, the limiting flux was 128±0.3, 109±4, and 97±0.5 kg/m2 per hour at recirculation loop TP concentrations of 8.1±0.07, 9.2±0.04, and 10.2±0.03%, respectively. For the 3-mm CD membranes, increasing the flux from the starting to the limiting flux decreased the SP removal factor from 0.72±0.02 to 0.67±0.01; however, no difference in SP removal factor among the target recirculation loop TP concentrations was detected. The limiting flux at each recirculation loop target TP concentration was lower for the 3- compared with the 4-mm CD membranes. The differences in limiting fluxes between the 3- and 4-mm CD membranes were explained in part by the difference in cross-flow velocity (5.5±0.03 and 7.0±0.03 m/s for the 3- and 4-mm CD membranes, respectively). The SP removal factor was also lower for the 3- compared with the 4-mm CD membranes, indicating that more membrane fouling may have occurred in the 3- versus 4-mm CD membranes.
authors.affiliation: Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853.
authors.forename: E E
authors.initials: EE
authors.lastname: Hurt
authors.affiliation: Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853.
authors.forename: M C
authors.initials: MC
authors.lastname: Adams
authors.affiliation: Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853. Electronic address: dmb37@cornell.edu.
authors.forename: D M
authors.initials: DM
authors.lastname: Barbano
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000737:chemistry*; D002516:Ceramics; D005374:Filtration / Q000295:instrumentation / Q000379:methods*; D005511:Food Handling / Q000295:instrumentation* / Q000379:methods; D008823:Micelles; D008892:Milk / Q000737:chemistry*
chemical_list: D001798:Blood Proteins; D008823:Micelles
keywords: limiting flux; microfiltration; serum protein removal