1、Desalination of SeawaterAWWA MANUAL M61First EditionM61.indb 1 4/21/2011 10:09:35 AMCopyright 2011 American Water Works Association. All Rights Reserved.MANUAL OF WATER SUPPLY PRACTICES M61, First EditionDesalination of SeawaterCopyright 2011 American Water Works AssociationAll rights reserved. No p
2、art of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publis
3、her.DisclaimerMany of the photographs and illustrative drawings that appear in this book have been furnished through the courtesy of various product distributors and manufacturers. Any mention of trade names, commercial products, or services does not constitute endorsement or recommendation for use
4、by the American Water Works Association or the US Environmental Protection Agency. In no event will AWWA be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of information presented in this book. In particular, AWWA will not be responsible for any cos
5、ts, including, but not limited to, those incurred as a result of lost revenue. In no event shall AWWAs liability exceed the amount paid for the purchase of this book.Project Manager/Senior Technical Editor: Melissa ValentineProduction Editor/Cover Design: Cheryl ArmstrongManuals Specialist: Molly Be
6、achLibrary of Congress Cataloging-in-Publication Data has been applied for.ISBN 1-58321-833-5978-1-58321-833-4Printed in the United States of AmericaAmerican Water Works Association6666 West Quincy Ave.Denver, CO 80235 Printed on recycled paperM61.indb 2 4/21/2011 10:09:36 AMCopyright 2011 American
7、Water Works Association. All Rights Reserved.ContentsiiiSeawater Desalination OverviewChapter 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1Introduction, 1Desalination Technologies Overview, 3Membrane Separation, 3Thermal Evaporation, 6Novel De
8、salination Processes in Development, 9References, 13Water QualityChapter 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Source Water Quality, 15Product Water Quality, 17Health Concerns, 17Produ
9、ct Water Stability, 21Irrigation and Industrial Use Concerns, 21General Aesthetic Concerns, 23References, 24Treatment ApproachesChapter 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Pretreatment, 27SWRO Design Paramete
10、rs, 33Disinfection, 36Posttreatment, 37Energy Recovery, 38Corrosion and Materials of Construction, 43References, 47Environmental Impacts and Mitigation MeasuresChapter 4 .49Introduction, 49Source Water Intakes, 50Concentrate Discharge, 57Management of Desalination Plant Residuals, 69Greenhouse Gas E
11、missionsImpacts and Management, 72Noise, Air Pollution, and Traffic, 79References, 80Cost of TreatmentChapter 5 .83Introduction, 83Summarizing Project Costs, 83Construction Costs, 85Estimating Capital Costs, 85Estimating Operation and Maintenance Costs, 89Financing Cost, 93Cost of Water, 94Summary,
12、94References, 98M61.indb 3 4/21/2011 10:09:36 AMCopyright 2011 American Water Works Association. All Rights Reserved.ivSafety and SecurityChapter 6 .99Safety, 99Security, 102M61.indb 4 4/21/2011 10:09:36 AMCopyright 2011 American Water Works Association. All Rights Reserved.FiguresvFigure 1-1 Global
13、 growth of desalination facilities 2Figure 1-2 Basic concept of osmosis and reverse osmosis.4Figure 1-3 Multistage flash distillation .8Figure 1-4 Multiple effect distillation 8Figure 1-5 Vapor compression 9Figure 1-6 Schematic of forward osmosis desalination process.10Figure 2-1 Sea-surface salinit
14、ies .16Figure 2-2 Boston Ivy with tip burn from chloride 20Figure 2-3 Boron toxicity on camphor.20Figure 3-1 Projected impact of recovery on power consumption for SWRO.34Figure 3-2 Projected SWRO feed pressure requirements as a function of influent water temperature for different flux rate and eleme
15、nt type35Figure 3-3 Projected impact of temperature on SWRO permeate boron 35Figure 3-4 Pelton wheel generators at Tampa Bay SWRO facility39Figure 3-5 Hydraulic turbocharger in an RO system.39Figure 3-6 ERI TurboCharger device (low pressure turbine) .39Figure 3-7 ERI PX energy recovery device flow d
16、iagram .40Figure 3-8 PX Pressure exchanger device installation in Sand City, Calif. 40Figure 3-9 Dual Work Pressure Exchanger flow diagram 41Figure 3-10 Installation of Flowserve DWEER energy recovery device .41Figure 3-11 Three center design layout .42Figure 3-12 Resistance to crevice corrosion 44F
17、igure 4-1 3.8 MGD intake beach well of a large seawater desalination plant .52Figure 4-2 Beach well intake system (above-grade completion) .52Figure 4-3 Beach well intake system (at grade completion).53Figure 4-4 Beach well intake system (dual completion) 53Figure 4-5 Tidal zone (onshore) discharge
18、of the Ashkelon SWRO Plant, Israel .60Figure 4-6 Perth SWRO Plant discharge configuration.61Figure 4-7 Perth desalination plant mixing zone62Figure 4-8 Perth desalination plant discharge diffuser rhodamine dye test .63Figure 4-9 5.5 MGD Santa Barbara seawater desalination plant, California.64Figure
19、4-10 Colocation concept for the Carlsbad Seawater Desalination Plant .66Figure 4-11 Colocation of Tampa Bay Seawater Desalination Plant 66Figure 4-12 32 MGD Carboneras SWRO plant in Spain67Figure 4-13 Carlsbad seawater desalination project73Figure 5-1 Seawater RO construction cost .86Figure 5-2 Seaw
20、ater RO cost of water .93M61.indb 5 4/21/2011 10:09:36 AMCopyright 2011 American Water Works Association. All Rights Reserved.M61.indb 6 4/21/2011 10:09:36 AMCopyright 2011 American Water Works Association. All Rights Reserved.TablesTable 1-1 Operational seawater desalination facilities in the Unite
21、d States 2Table 2-1 Seawater mineral quality compared to national source waters16Table 2-2 Pathogen reduction requirements for surface waters 19Table 3-1 Seawater RO pretreatment components for surface seawater sources .30Table 3-2 Seawater RO treatment advancements for surface seawater sources 31Ta
22、ble 3-3 Partial list of pretreatment installations in SWRO plants since 1995 .32Table 3-4 Log removal credits for potential treatment processes.37Table 3-5 Energy recovery devices (ERD): pros and cons .43Table 3-6 Galvanic series for alloys in flowing seawater at 4 m/s and 24C 44Table 3-7 PREN value
23、s for common materials.46Table 4-1 Potential impingement/entrainment reduction technologies 56Table 4-2 Concentrate disposal methods for existing desalination in the U.S. (including brackish RO, NF, and SWRO) .60Table 4-3 Residuals from seawater desalination processes .70Table 4-4 Comparison of wast
24、e streams from granular media and membrane pretreatment.71Table 4-5 Desalination project net GHG emission zero balance 78Table 4-6 Unit costs of carbon footprint reduction alternatives 78Table 5-1 Seawater intake alternatives cost example.95Table 5-2 Seawater RO plant capital cost example .96Table 5
25、-3 Annual Operation and Maintenance Cost Example Treatment Technology: SWRO .97Table 5-4 Annual Cost of Water Example Treatment Technology: SWRO (with a power plant) 97viiM61.indb 7 4/21/2011 10:09:36 AMCopyright 2011 American Water Works Association. All Rights Reserved.M61.indb 8 4/21/2011 10:09:3
26、6 AMCopyright 2011 American Water Works Association. All Rights Reserved.AcknowledgmentsixThe first edition of M61 was written through the persistent, dedicated work of the following authors:G. Wetterau, Chair, Camp, Dresser however, seawater desalination plants currently outnumber brackish water pl
27、ants by 60 percent worldwide (GWI 2009). Table 1 lists some of the more than two dozen seawater desalination plants built and operated in the United States. The majority of these facilities are industrial with a capac-ity of less than 1 million gallons per day (mgd) or 3.8 megaliters per day (MLD).
28、In addi-tion, a number of these plants are used intermittently because of the high cost of operation or problems experienced during operation. As coastal municipalities in the United States M61.indb 1 4/21/2011 10:09:38 AMCopyright 2011 American Water Works Association. All Rights Reserved.2 DESALIN
29、ATION OF SEAWATERbegin to consider implementing larger seawater facilities, it is essential to ensure that these are constructed and operated in an efficient and reliable fashion without adversely impacting fragile coastal environments. Large capacity, highly efficient seawater desalina-tion facilit
30、ies have been successfully implemented within the last five years in Australia, Singapore, Spain, and several countries in the Middle East. In the United States, there are currently more than two dozen new seawater projects in various stages of development, primarily in California, Texas, and Florid
31、a.The purpose of this manual of practice is to identify lessons learned from recent studies and seawater desalination projects around the world, and to use these to provide guidance for seawater desalination facilities that are reliable, economical, and environ-mentally sound. 010203040506070801990
32、1995 2000 2005 2010Cumulative Contracted CapacityMillion m3/dayCumulative Online Capacity Billion gpd 20 15 10 5 0Source: Global Water Intelligence 2010, data reproduced from DeSalD MarketsGlobal growth of desalination facilities Figure 1-1 Operational seawater desalination facilities in the United
33、StatesTable 1-1 Diablo Canyon, CA (0.6 mgd or 2.3 MLD) Tampa, FL (25 mgd or 95 MLD)Gaviota, CA (0.4 mgd or 1.5 MLD) Stock Island, FL (2 mgd or 8 MLD)Morro Bay, CA (0.6 mgd or 2.3 MLD) Marathon, FL (1 mgd or 4 MLD)Moss Landing, CA (0.5 mgd or 1.9 MLD) Kauai, HI (0.2 mgd or 0.8 MLD)Monterey Bay Aquari
34、um, CA (0.04 mgd or 0.15 MLD) Swansea, MA (2 mgd or 8 MLD)Sand City, CA (0.3 mgd or 1 MLD) Brockton, MA (5 mgd or 19 MLD)Avalon, CA (0.1 mgd or 0.4 MLD)Courtesy of Greg WetterauM61.indb 2 4/21/2011 10:09:38 AMCopyright 2011 American Water Works Association. All Rights Reserved.SEAWATER DESALINATION
35、OVERVIEW 3DESALINATION TECHNOLOGIES OVERVIEW _Desalination processes can be divided into two broad categories: membrane separation and thermal evaporation. Membrane-based desalination processes typically employ me-chanical pressure, electrical potential, or a concentration gradient as the driving fo
36、rce across a semi-permeable membrane barrier to achieve physical separation. Thermal de-salination processes employ heat to evaporate the water from a salt solution, and the water vapor is then condensed and recovered. Thermal technologies were the only options available for seawater desalination un
37、til reverse osmosis (RO) membranes were developed in the early 1960s. Since then, RO mem-brane processes have steadily been improved, and the efficiency has increased to the point that they are now the technology of choice for most seawater desalination applications. An exception to this is the Midd
38、le East, where low energy costs allow for thermal desalination to remain relatively competitive. Besides the established desalination technologies, there are several newer technolo-gies that are nearing commercialization or undergoing active research and development. A discussion of the established
39、membrane and thermal technologies is presented first in this manual, followed by a brief discussion of developing technologies. The remaining chapters in this manual focus on pressure-driven membrane applications, as this presently has the most applicability to seawater desalination in the United St
40、ates. MEMbRANE SEpARATION _Membrane desalination technologies have been designed around the ability of semi- permeable membranes to selectively permit or minimize the passage of certain ions. Three fundamental driving forces can be used in membrane desalination systems including pres-sure, electric
41、potential, and concentration gradient. RO and nanofiltration (NF) are pressure driven processes. Electrodialysis (ED) and electrodialysis reversal (EDR) are electric potential driven processes. Forward osmosis (FO) is a concentration-driven process.Membrane-based seawater desalination processes have
42、 typically applied only RO. Although NF and ED/EDR are also mature technologies and can be used for desalination, ED/EDR are typically not cost competitive for desalination of seawater (Amjad 1993), and NF is not ordinarily considered for seawater desalination for potable water production. However,
43、a novel approach employing two-pass (NF) configuration has been developed and tested for seawater desalination by the Long Beach Water Department in California. Similarly, FO is a developing technology and has not yet been commercialized for large-scale applications. Reverse Osmosis (RO)Desalination
44、 through RO is a well-established and nonproprietary unit process that cur-rently represents the state-of-the-art of desalination technology for a number of reasons. In addition to the ability to reject a variety of contaminants, RO treatment generally has lower energy consumption, lower feed water
45、flows, and no thermal impacts in the con-centrate discharge in comparison to thermal desalination processes. Improvements in membranes and energy recovery devices used for seawater RO (SWRO) have improved the overall process efficiency thereby lowering the costs associated with treatment. Reverse os
46、mosis is based on overcoming the natural phenomenon of osmotic pres-sure, which occurs when a semi-permeable membrane separates two solutions with dif-ferent concentrations of ions. The osmotic pressure created by the concentration gradient drives the flow of water from the dilute solution to the co
47、ncentrated solution, until chemi-cal equilibrium is established. The flow of water can be reversed with the application of an external hydraulic force (pressure) if this force is greater than the osmotic pressure. Figure 1-2 illustrates the basic concepts of osmosis and reverse osmosis. M61.indb 3 4
48、/21/2011 10:09:38 AMCopyright 2011 American Water Works Association. All Rights Reserved.4 DESALINATION OF SEAWATERSemi-Permeable MembraneWater FlowOsmosisReverse OsmosisWater FlowPressureCourtesy of Sandeep Sethibasic concept of osmosis and reverse osmosisFigure 1-2 RO membranes are designed to ret
49、ain salts and low-molecular weight solutes while allowing water to pass through. The original asymmetric cellulose acetate (CA) mem-branes, developed in the 1960s, were less permeable than modern thin-film compos-ite (TFC) membranes and required a higher driving pressure, in excess of 1200 pounds per square inch (psi) or 8.3 megapascals (MPa) for seawater at typical operating fluxes. Additionally, the ability of CA membranes to reject salts was origin
