Fresh Water for Arizona by Salt Replacement Desalination
Affiliation
Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721Issue Date
1974-04-20Keywords
Hydrology -- Arizona.Water resources development -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Desalination
Water chemistry
Desalination processes
Membrane processes
Reverse osmosis
Arizona
Water treatment
Water purification
Desalination plants
Costs
Saline water
Water supply
Cost comparisons
Solvent extractions
Water yield
Salt replacement desalination
Replacer chemical
Ultrafiltration
High flux membranes
Energy requirements
Fixed gel syneresis
Metadata
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Copyright ©, where appropriate, is held by the author.Collection Information
This article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact anashydrology@gmail.com.Publisher
Arizona-Nevada Academy of ScienceAbstract
The process of salt replacement desalination proposed is believed to be able to produce vast quantities of fresh water be desalination. This method, which is a novel approach to minimizing the costs of saline water conversion, consists of the substitution of solutes in a solution to be desalted by a replacer chemical, and the low energy removal of that replacer chemical. The ultrafiltration of larger molecular sized replacer chemicals with high flux membranes increases the produce yield rate and reduces the corresponding energy requirement, with respect to reverse osmosis. In addition, the initial captial investment is less since no pressure constraining devices are required. The alteration of the osmotic pressure of the replacer solution within the process can also take advantage of energy savings through the utilization of an easily reversible reaction which synthesizes and breaks down a constituent that has a significant osmotic pressure difference between phases. Finally, the unusual process of fixed gel syneresis shows potential as a low energy salt replacement type process, but still requires extensive investigation.ISSN
0272-6106Related items
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Economic Alternatives in Solving the U. S.-Mexico Colorado River Water Salinity Problem (invited)(Arizona-Nevada Academy of Science, 1974-04-20)A proposed desalting plant is an engineering solution to the effects of a problem which could have been avoided and even now could be reduced on the farm. Water costing $125 per acre-foot will be delivered to Mexico to grow wheat, cotton, garden crops, alfalfa and safflower, of which the average value added per acre-foot was estimated at $80 for cotton and garden crops and $14 for wheat, alfalfa and safflower. The U.S. government, instead of building the desalting complex, could accomplish its purpose just as well by paying each farmer in the Yuma area, in return for the farmers reducing their drainage flow by whatever method they see fit, $114 per acre per year for the next 50 years. With proper management on the farm, the costs of managing salinity need not be high.
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The Role of Water in the Energy-Water-Food Nexus: Optimization of Solar Desalination Systems and Novel Scaling Prevention Systems(The University of Arizona., 2018)Increasing demand in energy, water, and food industries necessitates considerations of the inextricable links between them to support sustainable growth. This dissertation explores the role of water in the energy-water-food nexus through discussion of three research projects. The first research project explores the energy-water nexus by discussing optimized solar-driven desalination systems for providing drinking water in remote areas. Many remote communities are disproportionately affected by water scarcity. Some regions have access to saline water sources, making desalination a viable method for mitigating water scarcity. However, these regions may lack access to central power, making solar driven desalination a potential solution. The objective of this research was to develop process models to simulate the non-steady operation of solar driven desalination technologies. Models were used to quantify the system efficiency or cost of water. Non-linear multi-variable optimization was performed to optimize the system by adjusting equipment sizes and operating parameters. In all cases, membrane distillation systems were more expensive than traditional solar desalination technologies. However, the cost of membrane distillation systems may be reduced by reducing costs of membrane modules and solar thermal collectors. The second research project explores the water-food nexus by discussing methods of recovering nutrients from domestic wastewater to secure a novel fertilizer source for sustainable food production. Phosphorous, an essential fertilizer component, is in short supply. However, there are high levels of phosphorous in municipal wastewater. Methods of recovering phosphorous are of great interest. Struvite (MgNH4PO4∙6H2O) is an insoluble mineral that forms in waters rich in phosphorous, especially in municipal wastewater treatment plants. Struvite scaling in processing equipment and pipes causes significant processing problems, but can be beneficial in a controlled environment as it can be recovered and used as fertilizer to help mitigate current phosphorous shortages. Current struvite control technologies, including ferric chloride, make recovery difficult, so alternatives are needed. A potential alternative is application of residual biogas, a byproduct of wastewater treatment rich in carbon dioxide, to lower the pH of wastewater as struvite is more soluble at low pH. CO2 may be easily stripped from solution, allowing for more economical struvite recovery. The purpose of this study was to investigate the feasibility of using residual carbon dioxide for struvite control. Bench- and pilot-scale experiments demonstrated the feasibility of using carbon dioxide to prevent struvite formation. Models were developed to predict the pH upon carbon dioxide addition and validated using experimental results. Finally, the models were used to develop a design tool to facilitate rapid implementation of sustainable struvite control systems at any wastewater treatment plant. This will allow for economical recovery of nutrients from wastewater to support expansion of sustainable farming practices. In the third and final project, the efficacy of a novel ion exchange material for removal of silica from cooling tower water was investigated. Silica is ubiquitous in industrial wastewaters and causes several scaling, prohibiting the recovery and reuse of wastewater. Calcined hydrotalcite (HTC) was demonstrated to be effective in selectively removing silica in batch and continuous experiments in the presence of competing cations. This technology represents a low-cost solution to silica scaling and will help reduce the water requirements of power generation and other industrial processes.
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MAXIMIZING WATER RECOVERY DURING REVERSE OSMOSIS (RO) TREATMENT OF CENTRAL ARIZONA PROJECT (CAP) WATER(The University of Arizona., 2009)Central Arizona Project water was treated using slow sand filtration (SSF) and reverse osmosis (RO) in series. Additional desalination water was recovered from RO brine using the vibratory shear-enhanced processing (VSEP®; New Logic, Inc.). SSF removed 90% of the turbidity in raw CAP water. SSF decreased total organic carbon by almost 20%. After a little more than a year of continuous operation, performance of the RO system declined noticeably, as indicated by a rapid decrease in membrane permeation coefficient and an increase in salt flux. Foulant scrapings contained both clay material and large amounts of unidentified organics. Alternative hypotheses regarding major sources of membrane foulants are discussed in this study.Water lost as brine was reduced from 20% to 2-4% via post-RO VSEP treatment. Estimated costs were compared to those of a no-VSEP option in which disposal of the entire RO brine flow was required. The total annualized cost of brine treatment was fairly insensitive to recovery during VSEP treatment in the range 80-90%, and the period of VSEP operation between cleanings in the range 25-40 hrs. These values define a fairly broad window for near optimal VSEP operation under the conditions of the study. The cost of VSEP treatment to minimize brine loss was estimated at $394- $430 per acre foot ($1.21 - $1.32 per 1000 gal) of 15 MGD CAP water treated. For a hypothetical 3 MGD RO brine flow, the use of VSEP to recover water and reduce the volume of brine for disposal results in a savings of more than $5M/year relative to the no-VSEP brine disposal alternative.
