Media granular

There are two major types of filtration "cake" and "filter-medium" filtration. In the former, solid particulates generate a cake on the surface of the filter medium. In filter-medium filtration (also referred to as clarification), solid particulates become entrapped within the complex pore structure of the filter medium. The filter medium for the latter case consists of cartridges or granular media. Among the most common examples of granular materials are sand or anthracite coal. 

The physical properties of loose and granular media are important, both from the standpoint of the operation of the filtration device, but also from the standpoints of feeding and storing these materials in bins and silos. These considerations are equally important and quite pertinent to dry chemicals that are used as filtration aids (Chapter 3). In a general sense, loose solid matter is comprised of large numbers... 

Granular media filtration is used for treating aqueous waste streams. The filter media consists of a bed of granular particles (typically sand or sand with anthracite or coal). The anthracite has adsorptive characteristics and hence can be beneficial in removing some biological and chemical contaminants in the wastewater. This material may also be substituted for activated charcoal. 

The filter application is typically applied to handling streams containing less than 100 to 200 mg/Liter suspended solids, depending on the required effluent level. Increased-suspended solids loading reduces the need for frequent backwashing. The suspended solids concentration of the filtered liquid depends on the particle size distribution, but typically, granular media filters are capable of producing a... 

R. W. Mair, R. Wang, M. S. Rosen, D. Candela, D. G. Cory, R. L. Walsworth 2003, (Applications of controlled-flow laser-polarized xenon gas to porous and granular media study), Magn. Reson. Imag. 21, 287. 

R. Garcia-Rojo, H. J. Herrmann, S. McNamara (eds.) 2005, Powder and Grains 2005 Proceedings of the 5th International Conference on Micromechanics of Granular Media, Stuttgart, 18-22 July 2005, A. A. Balkema, Leiden. 

Luding, S., Collisions contacts between two particles, in Physics of Dry Granular Media (H. J. Herrmann, J. P. Hovi, and S. Luding Eds.), p. 1-19. Kluwer Academic Publishers, Dordrecht (1998) Chpt. 5. 

Kemblowski, Z., DZIUBINSKI, M. and Mertl, J. Adv. in Transport Proc. 5 (1987) 117. Flow of non-Newtonian fluids through granular media. 

Microbes are ubiquitous in the subsurface environment and as such may play an important role in groundwater solute behavior. Microbes in the subsurface can influence pollutants by solubility enhancement, precipitation, or transformation (biodegradation) of the pollutant species. Microbes in the groundwater can act as colloids or participate in the processes of colloid formation. Bacterial attachment to granular media can be reversible or irreversible and it has been suggested that extracellular enzymes are present in the system. Extracellular exudates (slimes) can be sloughed-off and act to transport sorbed materials [122]. The stimulation of bacterial growth in the subsurface maybe considered as in situ formation of colloids. 

Both media filters and cartridge filters can be used in a pretreatment process. Granular media filters involve the filtration of large particles through different layers of fine particles, usually coal, pumice, sand or garnet (Bonnelye et al. 2004). Cartridge filters act as the final filtration step before the water passes through the membranes, and remove fine particles as small as 1 pm. 

Similar to filter backwash, the concentrate from these membranes requires treatment before it can be disposed of with the membrane concentrate. However, the total amount of solids produced after the treatment of filter backwash can be 60-80% greater than MF and UF concentrate due to the addition of coagulants prior to the granular media filters (Bergman 2007). 

Cortis A, Chen Y, Scher H, Berkowitz B (2004) Quantitative characterization of pore-scale disorder effects on transport in homogeneous granular media. Phys Rev E 70, 041108, DOl 10.1103/PhysRevE.70.041108... 

Coagulation, Sedimentation, Granular Media Filttation Ion Exchange Membrane Filtration Adsorption ... 

In general, it can be very difficult to determine the nature of the boundary terms. A specific result in an exactly solvable case is discussed in Section IV.A.2. Equation (55) is the Gallavotti-Cohen FT derived in the context of deterministic Anosov systems [28]. In that case, Sp stands for the so-called phase space compression factor. It has been experimentally tested by Ciliberto and co-workers in Rayleigh-Bemard convection [52] and turbulent flows [53]. Similar relations have also been tested in athermal systems, for example, in fluidized granular media [54] or the case of two-level systems in fluorescent diamond defects excited by light [55]. 

A. Farmer, Studies of Wave Propagation in Granular Media , RPI (Rensselaer Polytechnic Inst, Troy, NY), Report 00R, Contract No DA-30- 115-ORD- 459 (1955) 37a) S. Paterson,... 

Obviously, typical composite propellants are highly filled polymers and, especially in the case of the rubber-based systems, are more nearly granular media than merely filled rubbers. Certain specific differences between the double-base binder and the elastomeric binder lead to some differences in behavior, but many of the resulting properties show similarities. The relationships between bulk properties and microstructure in the rubber-based systems are much better understood than those of the double-base propellants and, therefore, the following discussions focus primarily on the former category. 

Often the production of new materials such as composite materials heavily involves processes at interfaces. Thin films on surfaces are often dominated by surface effects. Examples are latex-films, coatings, and paints. The flow behavior of powders and granular media is determined by surface forces. In tribology, wear is reduced by lubrication which again is a surface phenomenon. 

Table 2. Important relations related to fluid flow in granular media...

Sokolovskii, V. V. (1965). Statics of Granular Media. New York Pergamon Press. 

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