Page 230 - ro membanes

9.7 OVERVIEW OF MEMBRANE PRODUCTS USED FOR SALINE WATER PRETREATMENT 213
pore size of 0.08 mm and outside-in flow pattern. For comparison, the HYDRAcap 60 is inside-out type of UF membrane.
The key membrane performance parameters for the baseline HYDRAcap 60 membrane modules are presented below:
Membrane Type
Two widely used models
Typical operating pressure
Maximum feed pressure
Trans-membrane pressure that triggers backwash
Filtration cycle length
Backwash duration
Membrane material
Nominal pore size
Module diameter
Module length
Membrane module filtration area
Design flux
Number of modules needed to produce
1000 m3/day of filtrate
Ultrafiltration, Pressure Driven, Inside-Out Hydracap 60/60-LD
0.2e0.5 bar
3.0 bars
(Typically 1.1e1.4 bar)
15e60 min
30e60 s
Hydrophilic polyethersulfone (PES)
0.08
225 mm (8.8-in.)
1000 and 1500 mm (40-in. and 60-in.)
30 m2 (1000-mm module) and 46 m2 (1500-mm module)
60e100 L/m2 h
10e16 HYDRAcap 60 1500-mm modules
9.7.4 General Electric Water and Process Technologies
General Electric Water and Process Technologies (now part of Suez) offers both submerged and pressurized ZeeWeed UF pretreatment systems, with hollow-fiber membrane modules, which is operated in an outside-in-mode. The UF fibers of the submerged modules are com- bined into bundles, which are installed in standard-size modules (see Fig. 9.10). In the case of the pressurized UF membranes (ZW 1500), the membrane fibers are installed in vertical poly- vinyl chloride housings. To date, the main model that has found full-scale application for pre- treatment of seawater is the submerged ZW1000 PVDF membrane and its modified versions (see Table 9.7). Up to 96 membrane modules can be installed in a membrane cassette, and these cassettes are immersed into tanks fed with source water. Air scouring system is usually installed in the tanks to loosen and release the solids retained within the hollow fiber bundles during the backwash cycle of system operation.
The main difference between the versions of the original ZW1000 is the total membrane cassette surface area and reduced internal fiber diameter. The V2 version has a smaller sur- face area compared to the other versions because it is designed to handle higher solid loads