Ultrafiltration unit characteristics

The UF unit placed in the final stage of the poUshing system has an important function as a final filter to remove particles up to 50-nm size. The UF unit also completely eliminates bacteria from the system. The spiral-type UF imit has a compheated structure that allows particle leakage. On the other hand, the hollow-fiber structure is simple and capable of removing particles completely (Yabe, 1993). Consequently, hollow-fiber-type UF units are widely used in the polishing section of the ultrapure water systems. This ultrafiltration unit should possess the following necessary characteristics (Ishikawa, 1993) ... 

Ultrafiltration equipment are combined with other unit operations. The unique combination of unit operations depends on the wastewater characteristics and desired effluent quality, and cost considerations. 

Ultrafiltration, 631 applications, 633 membranes, 637-639 Underwood minimum reflux binaty, 387 multicomponent, 397 Units, conversion of, 671, 672 UMQUAC equation, 475 Upflow fixed beds, 609 Uranium recovery, 515 Utilities, typical characteristics, 15... 

Reverse osmosis units are used for molecular separations such as the removal of salt from seawater. Nanofiltration is another variant of membrane filtration whose separation characteristics fall between reverse osmosis and ultrafiltration. Their description is beyond the scope of this text. 

Ultraflltration is perfectly familiar in the industrial world and is used widely in numerous processes. The actual separation is carried out by the semi-permeable membrane itself, but the performance of the units, and especially the ultrafiltration flow rate and its regularity, depend on a number of factors the intrinsic properties of the membrane used, the operating conditions, and the characteristics of the modules in which the membranes operate. It is for this reason that the choice of ultrafiltration module technology is specially important for industrial applications, where economical considerations are at least of the same importance as technical ones. 

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