through these wide-bored tubes makes them fouling resistant. Tubular membranes can be easily cleaned by chemical
and mechanical methods after dismantling the module
assembly (MacNeil 1988). Tubular membrane modules find
limited applications in BWRO desalination processes. They
are being commonly applied in ultrafiltration and microfiltration applications (McCutchan and Goel 1974; Wiley et al.
1985; Tsuge et al. 1977).
4.4 Hollow Fiber Modules
After its development by Dow Chemical in 1966 for the first
time, cellulosic hollow fiber modules have been commercially produced, promoted and also patented by other companies too (Mahon 1966; Kumano and Fujiwara 2008).
Hollow fiber membrane modules for brackish water desalination are often manufactured in shell-side feed design as
Fig. 5 Exploded view of spiral
wound module. Some portion of
the brackish feed water flowing
along the axis of membrane
module permeates through the
membrane surface and travels
spirally inwards to the perforated
central collection pipe. The
retentate concentrated brine
axially moving through the
spacers is collected at the other
module end opposite to the feed
end
Fig. 6 Multi-envelope spiral
wound module having 6
envelopes. There may be dozens
of envelopes in larger diameter
modules
48
M. Sarfraz