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9.7 OVERVIEW OF MEMBRANE PRODUCTS USED FOR SALINE WATER PRETREATMENT 209
FIGURE 9.7 Pentair X-flow Seaguard ultrafiltration pretreatment system.
FIGURE 9.8 Pentair X-Flow Seaflex ultrafiltration pretreatment system.
is, therefore, more advantageous for directly coupled UF-RO systems than the vertical config- uration of the UF racks. However, the vertical configuration offers more compact design and smaller footprint, which ultimately results in lower overall capital costs. Therefore, this sys- tem is usually more attractive for large desalination plants with an interim tank and pump- station between the UF and RO systems.
All modules within the Seaflex X-line racks are fed from a common source water line. The Seaflex modules are directly attached to the feed lines and are not contained in a separate vessel compared to the Seaguard membrane modules, which are installed in horizontal hous- ings (vessels) and their filtrate tubes are connected with plastic interconnectors and O-rings similar to these used for interconnecting the RO membranes in their pressure vessels.
Both the Seaguard and Seaflex membrane pretreatment systems employ UF PES membranes with inside-out flow pattern and pore size of 0.020e0.025 mm. The horizontal Seaguard sys- tems have some similarities with RO systems in terms of vessel diameter and general config- uration. However, these systems have only four membrane elements (instead of seven or eight