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CHAPTER
8
Granular Media Filtration
8.1 Introduction 154
8.2 The Filter Operation Cycle 155
8.2.1 Source Water Filtration 155 8.2.2 Filter Media Backwash 156
8.3 Key Filtration System Components 158
8.3.1 Filter Cells 158
8.3.2 Filter Media 158
8.3.3 Media Support Layer and
Undertrain System 160
8.3.4 Service Facilities and Equipment 160
8.4 Filter Types and Configurations 161
8.4.1 Single-, Dual- and Trimedia
Filters 161
8.4.2 Single- and Two-Stage Filters 161
8.4.3 Downflow and Upflow Filters 162
8.4.4 Filters Combined With DAF
Clarifiers 162
8.4.5 Gravity and Pressure Filters 163
8.4.5.1 Gravity
FiltersdDescription 163
8.4.5.2 Gravity FilterseKey Advantages 163
8.4.5.3 Pressure
FiltersdDescription 166
8.4.5.4 Pressure FiltersdKey Advantages 167
8.5 Filter Performance 168
8.6 8.7
8.5.1 Removal of Solids 168
8.5.2 Removal of Organics 168
8.5.3 Removal of Microorganisms 169
8.5.3.1 Algae 169
8.5.3.2 Bacteria and Viruses 169
8.5.4 Monitoring of Filter
Performance 169
8.5.4.1 Iron-Coagulant
Overdosing 171
8.5.4.2 Sand and Anthracite
Media Intermixing 172
8.5.4.3 Filter-Media
Solidification and Mud
Ball Formation 173
8.5.4.4 Filter-Media
“Cratering” 174
8.5.4.5 Filter-Media Mounding 174
8.5.4.6 High Content of Fine
Silt in the Source
Water 175
Source Water Pretreatment Prior
to Granular Media Filtration 176
Planning and Design
Considerations 176 8.7.1 Single-Stage Dual-Media Filters 176
OUTLINE
Pretreatment for Reverse Osmosis Desalination
http://dx.doi.org/10.1016/B978-0-12-809953-7.00008-5 153 Copyright © 2017 Elsevier Inc. All rights reserved.