Abstract
The cake filtration theory of the cross-flow ultrafiltration was discussed in this paper. The flux of kaoline suspension under coagulation was investigated and the improvement effect of permeability flux under coagulation and backwashing was estimated using the cake filtration theory. The property of the coagulated flocs changes because of the circulation of the concentrated suspension. Although the floc density becomes large under high mixing intensity of circulation, the sedimentation efficiency of the floc separation changes according to ALT ratio. The permeability flux is improved by the addition of Alum. The effect of coagulation especially appears over the ALT ratio range, 0.01 and this Alum dosage is coincided with the optimum dosage of Jar test. Although the filtration rate Rf of kaoline suspension (ALT=0) without Alum and backwashing is 1.4m/d, Rf with backwashing of 10 minutes interval becomes 2.3m/d. This Rf value is equal to the Rf value of the coagulation condition of ALT=0.05 without backwashing.
