NAMS 2002 Workshop - ICOM 2008

Ultra- and Microfiltration I - Transport – 3
Wednesday July 16, 10:45 AM-11:15 AM, Wai’anae
Flux Recovery During Infrasonic Frequency Backpulsing of Micro- and
Ultrafiltration Membranes Fouled with Dextrin and Yeast
D. McLachlan (Speaker), UNESCO Assoc Centre for Macromolecules, Shellenbosch, South
Africa - davidsm@sun.ac.za
E. Shugman, UNESCO Assoc Centre for Macromolecules, Shellenbosch, South Africa
R. Sanderson, UNESCO Assoc Centre for Macromolecules, Shellenbosch, South Africa
The fouling of micro and ultra membrane filters during the filtration process
necessitates that they be cleaned regularly. Back pulsing cleaning, as presented
in this paper, has the advantage that the plant does not have to be shut down
and that there are no soaps to dispose of.
In this paper Micro and Ultra membranes (Alpha Laval polysulphone 0.1 micron
and 100 000 MWCO) are first fouled, using a feed pressure of 100 kPa, in a flat
cell, with Dextrin or Yeast. After this infrasound backpulsing, directly into the
permeate space, was used to clean the membrane. During the cleaning, the RO
feed pressure remained at100 kPa and the cross flow rate at 30lt/hr. The back
pulsing was done using permeate water and at peak pressures of 90, 140 and
180 kPa. The results to be given in the presentation show that flux values of over
80% of the clean water value, can be restored by this procedure. These results
also show that when applied correctly regular and frequent backpulsing can
maintain an overall higher flux.
The purpose of this work is to explore the efficiency of cleaning, various
combinations of membrane materials and foulants, using backpulsing in flat cells,
where changes can easily be effected. Work is done in conjunction with these
experiments, is the use of backpulsing to clean spiral wrap elements (see R D
Sanderson et al-these proceedings.)