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CHAPTER
7
Sand Removal, Sedimentation, and Dissolved Air Flotation
7.1 Introduction 137
7.2 Sand Removal Systems 138
7.2.1 Settling Canals and Retention
Basins 138
7.2.2 Strainers 138
7.3.4 Lamella SettlerdDesign
Example 142
7.4 Dissolved Air Flotation Clarifiers 144 7.4.1 Introduction 144 7.4.2 Planning and Design
7.2.3 Cyclone Separators 139 Considerations 146
7.3 Sedimentation Tanks 139
7.3.1 Introduction 139
7.3.2 Conventional Sedimentation
Tanks 141
7.3.3 Lamella Sedimentation Tanks 141
7.4.3 DAFdDesign Example 150 7.5 Construction Costs of Lamella
Settlers and DAF Clarifiers 150 References 152
OUTLINE
7.1 INTRODUCTION
The purpose of sand removal, sedimentation, and dissolved flotation pretreatment sys- tems is to minimize the content of coarse materials such as grit, debris, and suspended solids collected by the plant intake and protect downstream filtration facilities from solids’ overload. The source water collected by onshore intakes and shallow open offshore intakes usually does not contain large quantities of sand but could have elevated content of floating and suspended solids. Well intakes typically have a very low content of suspended
Pretreatment for Reverse Osmosis Desalination
http://dx.doi.org/10.1016/B978-0-12-809953-7.00007-3 137 Copyright © 2017 Elsevier Inc. All rights reserved.
