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Abstract
Vertical ultrafiltration experiments of silica colloid and bovine serum albumin solution were conducted in the single-pass mode by using a hollow fiber membrane module and beneficial in measuring the time evolution of the growth rate of the filter cake during filtration. The extremely small mass flux of the concentrate enabled us to highly concentrate the feed solution on the principle of vertical ultrafiltration in which the filter cake formed on the membrane surface is exfoliated continuously. Both growth and re-entrainment rates of the filter cake formed in vertical ultrafiltration were evaluated from the experimental data of the filtration rate and the mass fraction ratio of the concentrate on the basis of the mass balance within the hollow fiber membrane module. As a consequence, it was found that the re-entrainment rate of the filter cake increased almost linearly with the filtration time in the initial period of filtration and then tended to rapidly approach a constant value. The filter cake stopped growing under this dynamically balanced condition. The variations of the average specific resistance of the filter cake with time were also determined from the time evolutions of both the filtration rate and the growth rate of the filter cake.
ACKNOWLEDGEMENTS
This work has been partially supported by Grant-in-Aids for Scientific Research from The Ministry of Education, Culture, Sports, Science and Technology, Japan and from The Ministry of the Environment, Japan. The authors wish to acknowledge with sincere gratitude the financial support leading to the publication of this article. The authors also wish to express their sincere appreciation to Asahi Kasei Chemicals Corp. for the generous contributions of the hollow fiber cartridge used in this research.