Determination of cake filtration characteristics of dilute suspension of bentonite from various filtration tests

Various types of filtration experiments of dilute bentonite suspension were performed by using the fully automated and computer-driven experimental apparatus equipped with an unstirred batch filtration cell. The filtration tests conducted were the single constant pressure filtration test with an appreciable membrane resistance, a series of constant pressure filtration tests with the negligible membrane resistance under conditions of various filtration pressures, a constant rate filtration test, and a variable-pressure, variable-rate filtration test. The experimental data of the time variation of both the filtration rate and applied filtration pressure monitored throughout the course of filtration enabled us to evaluate the relation between the average specific cake resistance αav of the filter cake and the applied filtration pressure p. The logarithmic plots of αav vs. Δpc have roughly merged into a unique curve irrespective of the type of filtration tests. The plots were approximated by a straight line over the moderate and high pressure ranges, and approached asymptotically to a constant value as the pressure decreased. The relation between αav and Δpc was fairly consistent with the empirical equation presented by Tiller et al. and the expression presented in this paper over wide ranges of the pressure.

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► Filtration characteristics of dilute suspension were examined from filtration tests.
► The variations with time of the filtration rate and applied pressure were measured.
► Specific cake resistance αav was related to the pressure drop Δpc across the cake.
► The plots of αav vs. Δpc showed a unique curve irrespective of the type of tests.
► The relation between αav and Δpc was well described by the empirical equations.