Under the stimulus of the rheological experimental results which were reported in 1964 [M. Yusa and A. M. Gaudin,
Am. Ceram. Soc. Bull., 43, 402], a new solid-liquid separation process which is referred to as “pelleting flocculation process” has been developed and industrialized [M. Yusa, H. Suzuki, and S. Tanaka,
J. Am. Water Works Assoc., 67, 397, 1975].
The term “flocculation” is usually defined as the “transport process”, in which dispersed particles are brought together by thermal motion and/or fluid motion [W. J. Weber, Jr.,
Physicochemical Processes for Water Quality Control, Wiley-Interscience, pp.92~93, 1972]. The definition of flocculation seems not applicable to the pelleting flocculation. From a new angle, flocculation has been defined as the phenomenon, in which dispersed particles are transported by thermal motion and/or fluid motion, and some structure is induced among the particles that were brought together by the transport process. The structure induced among the particles is usually referred to as “flocculated structure”. It somehow has not come under our notice so far that the “flocculated structure” concept is essential fully to understand the phenomenon of flocculation. Subsequently, it has been proposed to establish a new branch of applied science to be known as “flocculation engineering”, defined as “a branch of science to originate and develop the technique of making the flocculated structure that fits the purpose of any process, through some suitable method of controlled the conditions of flocculation”.
Furthermore, the above-mentioned data reported in 1964 and the relationship between the pelleting flocculation and the traditional theories of flocculation have been discussed, proving the great possibilities of flocculation engineering. Clearly, the pelleting flocculation process forms a part of flocculation engineering. Finally, the “flocculated structure model” has been proposed, which consists of 1) random floating structure, 2) random capillary II structure, 3) random capillary I structure, and 4) random packed structure. Simultaneously, the schematic representation of the model has been presented. The model may become the basic starting point of flocculation engineering.
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