Water and Sustainable Development Opportunities for the Chemical Sciences: A Workshop Report to the Chemical Sciences Roundtable (2004) / Chapter Skim
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Water Quality and Supply: Analysis and Treatment
Water Quality and Supply: Analysis and Treatment
4 Desalination: Limitations and Challenges
Pages 27-39
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Water Quality and Supply: Analysis and Treatment
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From page 29... ...
Currently, desalination projects are funded on a case-by-case basis where 10-40 percent of the actual capital cost to build new desalination plants comes from some kind of government subsidy. A historical look at desalination costs for seawater RO shows that the price has come down an order of magnitude, currently in the range of $2-3 per thousand gallons.
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The process started with a vision that by 2020, desalination and water purification technologies will contribute significantly to ensuring a safe, sustainable, affordable, and adequate water supply for the Unites States. High-level needs include meeting drinking water standards, meeting agriculture and industry standards, enhancing water security, meeting today's need without compromising our future supplies, providing water in the future at a cost comparable to today' s, and ensuring local and regional availability through periods of episodic shortages (droughts)
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New Mexico is considering adding some of that water to the Pecos River as a way of meeting interstate compacts between Mexico and Texas. The main issue relative to oil and gas is developing cost-effective pretreatment to deal with small hydrocarbon residuals, again reducing the cost and ensuring water quality standards.
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From page 32... ...
Current-generation desalination technologies are drawn from these five technology areas, and it is from these areas that revolutionary, next-generation desalination technologies are expected to emerge. Figure 4.6 gives the standard breakdown of the costs to treat water; roughly 37 percent of seawater desalination is ':-__ \ R&D R&D R&D R&D R&D R&D R&D \ R&D R&D - R&D assigned to fixed charges, and this translates into things such as flux through membranes because that defines the plant size.
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Concentrate management is now growing in importance as we realize that disposal of concentrate in many cases is the limiting part of desalination processes. Alternative technologies include any desalination methodology not included in the other areas.
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34 WATER AND SUSTAINABLE DEVELOPMENT VARI-RO Positive Displacement (Pressure to Pressure Energy Transfer) PRODUCT WATER PATENTS ISSUED & PENDING FEED l HYDRAULIC DRIVE DISCHARGE WILD CONCENTRATE PD1 1 c-VRO BlkDiagWDUequ 3-16-99 FIGURE 4.8 The VARI-RO positive displacement process and pilot plant.
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From page 35... ...
Thermal Technologies This approach involves a thermal distillation process to produce fresh water from seawater and represents about onehalf of the world's installed desalination capacity. R&D thrust areas for thermal technologies are shown in Box 4.2.
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In the low-risk, low-reward environment, there is little driving force for utilities to try field processes on their own. The end result is that the only way you get a lot of new
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Figure 4.10 provides a view of the comprehensive implementation strategy. The Roadmap actually sits in the upper left-hand corner, where new technologies are developed.
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This presents the potential for separating fresh water and concentrate in a different kind of environment where the minimum energy is constrained only by how small the flow field can be made. Escalating Costs Tom Dillion, of Science Applications International Corporation (SAIC)
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As a national issue, SNL recognizes that long-term water supply issues in the United States represent a destabilizing environment in which all of us are functioning now. The destabilizing environment, both inside and outside the country, is something that has to be dealt with to make the world a more stable place.
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