Shuji Nakatsuka

The Terzaghi-Voigt combined model for constant-pressure consolidation of filter cakes and homogeneous semi-solid materials

Abstract Theories of constant-pressure consolidation are reexamined in detail. A Voigt model for constant-pressure consolidation is solved and the time factors which govern a secondary consolidation process are obtained. It is found that three kinds of retardation times exist in the solution of the Terzaghi-Voigt combined model; the first factor, Θ 1 , is due to liquid flow resistance of the Terzaghi element; the second, Θ 2 , is due to liquid flow resistance of the Voigt element; and the third, Θ 3 , is due to creep deformation of the particulate bed. One can derive the conventional solutions of the Terzaghi-Voigt combined model for constant-pressure consolidation under the normal assumption that both Θ 1 and Θ 2 are much less than Θ 3 .

Experimental analysis of flux decline mechanism of batch ultrafiltration (filtration characteristics of gel layer)

Abstract In order to make the so-called membrane fouling phenomena during ultrafiltration clearer, it is Important to visualise, by any means, the characteristics of the gel layer formed on the membrane surface. Unstirred dead-end ultrafiltration experiments were conducted under constant pressure, by using a newly-designed batchwise filter which had a sudden change in its filtration area. The variation in gel cake thickness with time, was determined on the basis of experimental measurements and then the overall characteristic values, such as the average specific filtration resistance, average porosity and the ratio of wet to dry cake mass were calculated on the basis of experimentally determined gel cake thickness. It has become evident that the relationship between filtration characteristics and operating conditions can be thoroughly analysed on the same basis as the conventional cake filtration theories or concept.