Some aspects of hydraulic transport of animal wastes

Note:Evidence from reported studies on osmotic or swelling pressure of active clay soil shows that at close particleseparation distances, additional repulsive forces, not generally considered in the standard Derjaguin-LandauVerwey- Overbeek (DLVO) model which incorporates Van der Waals attraction and double layer repulsion forces, could account for unpredictable volume changes or pressures. In this study, the role of ion hydration energy, not accounted for by the DLVO model, is investigated with regard to its contribution to the equilibrium pressure developed between Na-montmorillonite particles at small separation distances. The model proposed in the present study suggests that development of Coulomb and ion hydration energies in the inner and outer Helmholtz layers, in combination with other energies of interaction described by the DLVO model, can predict the actual performance of Na-montmorillonite under load at both short and large distances between particles.The capability of the proposed model to predict and explain the experimental results of isothermal adsorption -i desorption behaviour of heavy metal ion species such as Zn, cu, and Pb, to Na and ca-montmorillonite particles in conjunction with the law of mass-action was examined. It is concluded that the proposed model leads to a better understanding of the interaction mechanism between water molecules, ionic species and the clay particle surface.Il a ete demontre dans les etudes rapportees ici, sur la pression osrnotique ou le gonflerrent de 1 1argile active que, si les distances separantes entre les particules sont proches, des forces repulsives additionnelles, qui ne sont pas generalerrent considerees dans le rrodele Derjaguin-Landau-VerweyOverbeek DLVO, (qui camprend la force d 1attraction de Van der Waals et la force de repulsion a double couches) pouvaient justifier les changerrents imprevisibles de volume ou des pressions. Dans ces etudes, le role de l'energie d'hydratation des ions, non considere par le rrodele DLVO a ete examine pour investiger sa contribution a lapression d 1equilibre, developpee entre les particules Na-roontirorillonite, dans le cas de petites distances de separation. Le rrodele, propose dans l'etude presentee, suggere que le developperrent des energies de Coulanb et d 'hydratation des ions dans les couches internes et externes d 1 Hltl..mholtz, canbinees a d I autres energies d I interactions decrites par le rrodele DLVO, peut prevoir la performance reelle de Na-roontmorillonite sous l'effet d'une charge dans le cas de petites et grandes distances entre les particules.La capaci te du rrodele propose pour prevoir et expliquer les resul tats experimentaux du camporterrent de 1' isotherrre d' adsorption-desorption des especes ioniques de metaux lourds tels que Zn, Cu et Pb parmi les particules Na et Ca-roontirorillonite, conjointement a la loi d'action de masse, fut iiiexaminee. Il en est conlu que le modele conduit a une meilleure carprehension du mecanisme d'interaction entre les molecules d'eau, les especes ioniques et la surface des particules d'argile