Particle Deposition and Trapping

The suspended solid particle size and the volume of effluent also must be considered in examining deposition in the subsurface. For example, under leaching of a waste disposal site or following irrigation with sewage effluent, the coarse fraction of suspended solids is retained in the upper layer, while the finer colloidal fraction is more mobile, and its transport is controlled by the porosity of the subsurface solid phase. 

Particle deposition from aqueous suspensions onto stationary surfaces is a dynamic phenomenon characterized by a transient or time-dependent rate of deposition. The deposition of contaminated suspended particles is affected by the nature of the surrounding porous medium. A declining deposition rate is observed when particle-particle interactions are repulsive, so that the potential deposition zone becomes progressively occluded as particles accumulate this leads to a blocking phenomenon. 

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