2.6. Experiments and measurements
2.6.1. Membrane water flux
The membrane water flux was measured at the beginning of the
experiment and after the first and second rinsing. Distilled water
was used as feeding solution and measurements were performed
at 25 C and at transmembrane pressure of 2 bar.
2.6.2. Membrane fouling
The fouling tests were carried out with BSA at transmembrane
pressure of 2 bar, at 25 C and during 2 h. The cross-flow velocity
was maintained at 2.0 m/s. To keep the BSA concentration constant
both the permeate and the retentate streams were continuously
recirculated to the feed tank. The flux was measured each 3 min
using a balance KB-800-2 (Kern, Germany) with an accuracy of
±0.01 g. The permeate flux was calculated from mass data, changing
to volume data considering the permeate density as the water
density at the operating temperature. Thus, flux was calculated
dividing the difference between permeate volumes by the time
between measurements and the membrane area.