A New Model for the Analysis of Constant-Current Electro-Osmotic Dewatering of Preconsolidated Sludge

M. Iwata, M.S. Jami, and M. Sato (Japan)


Sludge handling, electroosmosis, dewatering, colloidal particle, and creep deformation


A constant-current electro-osmotic dewatering is analyzed by use of the combined Terzaghi-Voigt model for considering creep deformation of the material. The basic differential equation based on the model is solved analytically by assuming that both an electro-osmotic pressure gradient Epg and a modified consolidation coefficient Ce of the material are constant. The progress of electro-osmotic dewatering can be represented by an average consolidation ratio Uc as in mechanical expression. Both Ce and Epg increase with an electric current density i. A larger Ce leads to a higher dewatering rate; a larger Epg results in a higher solid compressive pressure distribution in the material. It is found that the amount of creep deformation depends upon the dewatering rate; the faster the dewatering rate, the larger the creep deformation, i.e., the creep deformation is more remarkable when a higher current density is applied to the material.

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