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CHAPTER
5
Pretreatment by Screening
5.1 Introduction 95
5.2 Bar, Band, and Drum Screens 96
5.2.1 Coarse Bar Screens (Bar Racks) 96 5.2.2 Fine Screens 97 5.2.2.1 Rotating Screens 97 5.2.2.2 Band Screens 98 5.2.2.3 Drum Screens 100 5.2.2.4 Wedge-Wire Screens 101
5.2.3 Construction Costs of Drum-
and Band Screens 102
5.3 Microscreens 103
5.3.1 Types and Configurations 103 5.3.2 Design Example 106 5.3.3 Costs of Microscreens 107
5.4 Cartridge Filters 107
5.4.1 Types and Configurations 107 5.4.2 Planning and Design
Considerations 108 5.4.3 Design Example 110 5.4.4 Construction Costs of Cartridge
References
Filter System 111
111
OUTLINE
5.1 INTRODUCTION
Screens are the first pretreatment step of every desalination plant. Depending on their type and use, they are incorporated into the intake system and/or are located downstream of the intake and upstream of the reverse osmosis (RO) system. The main purpose of screens is to remove large solid particles contained in the saline source water to protect the other pretreat- ment facilities or the RO system from equipment and structural damage, accelerated filter media clogging and fouling, and accelerated reduction of product water treatment capacity.
Depending on the type of intake and the quality of the saline source water it collects, screening equipment may be as simple as cartridge or bag filters, or as sophisticated as series of mechanical screens of various sizes designed to sequentially remove large debris and
Pretreatment for Reverse Osmosis Desalination
http://dx.doi.org/10.1016/B978-0-12-809953-7.00005-X 95 Copyright © 2017 Elsevier Inc. All rights reserved.
