Page 196 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

WATER TREATMENT AND PURIFICATION

4.32 CHAPTER FOUR

FIGURE 4.10 Hollow fiber reverse osmosis
configuration.

practical. Rejection characteristics are expressed as a percent of the specific impurities
retained and depend on ionic charge and size.
Membrane Module Configurations. There are four types of membrane module configu-
rations used for RO applications: hollow fiber, spiral wound (SWRO), tubular (TRO), and
plate and frame. Hollow fiber and spiral wound are the most common configurations. In
each design, maximum turbulence is necessary to avoid concentration polarization.
Hollow-Fiber Reverse Osmosis. The hollow-fiber configuration, illustrated in Fig. 4.10,
consists of a perforated tube manufactured from ceramic, carbon, or porous plastic with
inside diameters ranging from 1/8 to 1 in (8 to 25 mm). They require rigid support when
mounted inside the pressure vessel. Feedwater can be introduced either into the center or
outside depending on the manufacturer of the RO module. Fouling resistance is low.
Spiral Wound Reverse Osmosis (SWRO). This configuration, illustrated in Fig. 4.11, typi-
cally achieves a large surface area per unit volume. In this design, a flat membrane is formed

FIGURE 4.11 Spiral wound reverse osmosis configuration.

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