P. Moulin et al., Flux improvement by Dean vortices: ultrafiltration of colloidal suspensions and macromolecular solutions, J MEMBR SCI, 156(1), 1999, pp. 109-130
Coiled and straight hollow-fibre modules have been built and tested; the pe
rmeate flux obtained in ultrafiltration with these two geometries is compar
ed for two feeds: a colloidal bentonite suspension and a dextran solution.
In the case of colloidal suspensions, the secondary flows induced by the co
iled geometry allow fouling to be reduced and the permeate flux is multipli
ed by a factor of up to 2. An empirical relationship is proposed to express
the limiting flux of permeate as a function of both the velocity and some
geometrical parameters of the coiled modules. Analogous results are obtaine
d during the ultrafiltration of dextran. It is also shown that under certai
n conditions almost no deposit was formed; the permeate flux under these co
nditions is three times higher for coiled modules than for straight ones. F
or a given energy expenditure and ultrafiltration process, the gain in perm
eate flux can reach a factor of 1.8. (C) 1999 Elsevier Science B.V. All rig
hts reserved.