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Membrane technology 17
Scale in metres
1 I 0-9 10-8 10-7 10-6 10-5
! I
i Approximate Molecular Wdight in Daltonp
~
I
‘
2b0 20, boo
I
”).. 1- -m i 500,000
Small co
Free organic Album1 Iloids: I Bacterl
atoms n ionmsrs en protein I
Colloi dal silica
Sugars I I I
ra! I
hermciaer
W1
Pestlcides
c )issolved Endotoxi nsi
salts W‘oger IS
I
leverse osmodis
damfiltration
I E P
Increasing pumping energy
Figure 2.1 Membrane separation processes overview (from Stephenson et al., 2000, reproduced with
permission)
(a) (b)
Figure 2.2 Anisotropic UF membranes: (a) polymeric (thickness of ‘‘skin” indicated), and (b) ceramic (by
kindpermission of Zonpure)
through the membrane. Certain porous membranes are also homogeneous, but
these tend to have a correspondingly low permeability.
2.1.3 Membrane materials and their manufacture
Membrane manufacture ostensibly concerns the production of a permeable
material at a reasonable cost. The membrane cost is dependent on not only the
