Membrane and Desalination Technologies - TCE Moodle Website

250 L.K. Wang et al.
4.2. Uniform Transmembrane Pressure (UTP) System
Figure 6.9 shows a double loop constant-pressure membrane process system, also known
as the Bactocatch process (27). The process requires the simultaneous operation of a retentate
pumping loop and a permeate pumping loop, to simulate a backwashing operation, but in a
continuous manner rather than the periodic or intermittent traditional practice. With two
parallel flows adjusted so that the pressure drop is the same on the permeate and retentate
sides of the module, the pressure profile would be more like that shown in Fig. 6.10b instead
of the conventional membrane process system’s pressure profile shown in Fig. 6.10a. The flux
stays high and the rejection remains low (27).
5. APPLICATIONS OF MEMBRANE TECHNOLOGY IN
THE FOOD INDUSTRY
5.1. Production of Dairy Products Using MF, UF, and RO
Figure 6.11 shows various applications of MF, UF, and RO for processing milk:
1. Production of high-fat cream and fat-free milk using MF
2. Production of cheese, specialty milk products, total protein isolates, lactose, fermented food and
nonfood products using UF
3. Production of whole milk powder, bulk milk, and special milk products using RO
Figure 6.12 shows how MF, UF, and RO can be connected in series for the processing of
milk by sequential operations.
In each case in Figs. 6.11 and 6.12, the main applications of MF in milk or whey processing
are fat separation, bacterial removal, and caseinate recovery. The bacteria and fat in milk
products are considerably larger in molecular size than all other components. A membrane
RETENTATE
PERMEATE
FEED
PERMEATE
LOOP
Fig. 6.9. Uniform transmembrane pressure membrane (UTP) process system.