Membrane and Desalination Technologies - TCE Moodle Website

258 L.K. Wang et al.
energy consumption of industrial effluent treatment using the conventional system are high
due to high effluent flow.
Figure 6.17 shows a leaner production system (33) involving: (a) the use of MF for the
replacement of the conventional centrifuge or filter press for yeast cell harvesting; and (b) the
use of NF for treating and recycling the wash water. Since the NF membrane gives high flux
while rejecting 97% of COD and 56% of BOD, it yields a retentate with tenfold reduction in
volume, and a clean recyclable permeate. Since most of the wash water from the osmotic
dehydration process is purified and recycled by NF, the size of the evaporator and the digester
shown in Fig. 6.17 are significantly reduced resulting in savings in capital costs and energy.
5.6. Production of Cyclodextrin from Starch Using CMR, UF, and NF
Table 6.5 summarizes the food processing applications of membrane technology for dairy,
fruits and vegetable processing plants, and further introduces additional food processing
applications for animal products, beverage, sugar, fuel, and grain processing plants (3).
The advanced membrane processes are continuous membrane reactor (CMR), pervaporation
(PV) system and advanced ion-exchange membrane system, shown in Figs. 6.18–6.22,
respectively.
CMR continuously produces product water (permeate) and recycles the biological cells
(retentate) to an upstream fermentation vessel for reuse (Figs. 6.18 and 6.19). CMR has been
Fig. 6.17. Production of yeast using MF and NF.