NAMS 2002 Workshop - ICOM 2008

Silica colloidal solution with different particle sizes was used throughout.
Preliminary experimental results revealed that CFS-MFI is linearly dependent of
feed concentration as well as permeate flux. In a range of experiments where
22nm mono particle size silica solution was used, CFS-MFI values appeared to
be lower than MFI-UF values but only to a small extent, ranging from 200 to
500s/L 2 for operating flux of 25 to 120LMH. The influence of CFS is vaguely
shown in these experiments might be due to the narrow particle distribution. In
order to observe the clear effect of CFS on the MFI value, the silica mixture
solution of 50ppm of 22nm silica colloidal and 70nm to 100nm silica colloidal
suspension was used for another set of experiments. CFS-MFI shows significant
lower value than MFI-UF. Under constant flux of 52LMH, CFS-MFI was found to
be 76368s/L 2 whilst MFI-UF was 87878s/L 2 . The difference of MFI-UF and CFS-
MFI can range from 500 to 12000s/L 2 at permeate flux of 28 LMH, 52 LMH and
77 LMH. Results implied that the conventional method may have overestimated
the fouling propensity of the RO feed solution. The effects of other operating
variables such as feed composition, permeate flux and crossflow velocity were
also investigated in the study.
Acknowledgements
The authors would like to thank Department of Education, Science and Training, Australia for
their financial support and this study is collaborated with the European Union 6th Framework
project, Membrane-Based Desalination: An Integrated Approach (MEDINA).