Filtration packing

Biological columns are large-sized concrete or masonry structures, usually round with a gridded base. They are filled with filtration packing through which treated wastewater flows downstream (Fig. 4.25). 

Chromatography/ Batch Gel filtration, packed bed adsorption (PBA) chromatography, granular activated... 

Includes cyclonic, dynamic, filtration, inertial impaction (wetted targets, packed towers, turbulent targets), spray chambers, and venturi. 

Taub, "Filtration Phenomena ia a Packed Bed Filter," Ph.D. Thesis, Camegie-MeUon University, Pittsburgh, Pa., 1970. 

A common surface cartridge is the pleated paper constmction type, which allows larger filtration areas to be packed iato a small space. Oil filters ia the automobile iadustry are of this type. The paper is impregnated, for strength, with epoxy or polyurethane resia. Any other medium ia sheet form, similar to cellulose paper, such as wool, polypropylene, or glass may be used. 

The material is filtered and the residual solid washed twice with 50-ml. portions of low-boiling petroleum ether. The combined filtrates are concentrated and distilled through a short packed column to yield 190-205 g. (76-82%) of 2,2,5,5-tetra-methyltetrahydro-3-ketofuran b.p. 149-151°, d 1-4180. 

Another feature of an extruder is the presence of a gauze filter after the screw and before the die. This effectively filters out any inhomogeneous material which might otherwise clog the die. These screen packs as they are called, will normally filter the melt to 120-150 fim. However, there is conclusive evidence to show that even smaller particles than this can initiate cracks in plastics extrudates e.g. polyethylene pressure pipes. In such cases it has been found that fine melt filtration ( 45 p.m) can significantly improve the performance of the extrudate. 

Filtration is the concentration of solids (or clarification of liquor) from slurry by fluid flow through a permeable medium. This normally takes the form of a membrane, filter leaf or packed bed, which restricts the particles, more than the fluid (Figure 4.4). 

---