No description available.

Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. James B. Cowart, Florida State University, College of Arts and Sciences, Dept. of Geological Sciences. Title and description from dissertation home page (viewed Oct. 1, 2003). Includes bibliographical references.

Small-scale estuarine plume discharges into adjacent seas are common inshore features responsible for the transportation and dispersion of brackish water in the coastal zone. However, the physics that govern small-scale mixing in the frontal regions of river plumes are still poorly understood. The current study quantified and compared the observed hydrodynamic properties present inside a radially spreading river plume discharge from the River Teign, Teignmouth, Devon, UK, to those predicted by a generic plume model. Numerical simulations designed to replicate time dependent radial plume spreading from a constant source predicted the development of an internal interfacial bore that lagged the surface plume front through radial distance and time from initial plume release. The model was scaled from time lapse X-band radar imagery that recorded several plume discharge events. Scaled model output predicted the internal bore to form approximately 180 m behind the leading surface front. Subsequent field studies employed instrumentation capable of recording high-resolution measurements of temperature, salinity and velocity, spatially and vertically throughout the plume's buoyant layer over two ebb tidal cycles. Results suggested the plume advanced at a rate dependent on a super-critical interfacial Froude number of O(1.3) and was a region of intense mixing and downward mass entrainment. Temperature contours recorded through the stratified plume gave no indication of an internal bore in its predicted position but did show an abrupt shallowing of the interfacial region some 40 to 60 m behind the surface plume front. Super-critical interfacial Froude and critical Gradient Richardson numbers present in this region of the plume implied that this was the position of the predicted bore. The form of the bore often appeared as an ensemble of undular internal hydraulic jumps rather than a singular discontinuity as predicted by the model. Bulk mixing analysis inside the leading front based on established gravity current theory suggested that the extent of turbulent exchange in the model frontal boundary condition P, was underestimated by about a factor of 2. With the required increase in P, model simulations showed a decrease in the lag distance of internal bore formation to one where critical Froude numbers were detected inside the actual plume. Throughout both surveys, the gravity head remained a reasonably constant size due to any increase in across frontal velocity over the ebb tidal cycle being matched by an increase in entrainment and mixing. The subsequent conclusions from the study show the outflow and mixing dynamics are controlled by the estuary's tidal modulation of estuarine brackish water outflow / plume inflow rate behind the leading plume frontal discontinuity.

For presentation at the International Symposium on Brackish Water as a Factor in Development, by the Desert Research Institute at Sede-Boqer at the Ben-Gurion University of the Negev, Beer-Sheva, Israel, January 5-10, 1975. / Introduction: The Safford Valley area lies along the Gila River in the southeastern part of the State of Arizona. The portion of the valley being considered, see Figure 1, is an intermontane trough averaging about 15 miles (24.2 kilometers) in width and about 30 miles (48.3 kilometers) in length. The cultivated lands lie along the Gila River and are 0.5 to 3.5 miles (0.8 to 5.6 kilometers) from the river. The approximately 14,000 inhabitants of the valley are primarily located in the municipalities, and Safford, the largest of the towns, was founded in 1875. Agriculture and agriculture-dependent activities, however, provide the mainstay of the Safford Valley economy accounting for approximately 63 percent of the export employment (State of Arizona, 1971). Like many valleys in arid regions, the Safford Valley, because of an inadequate supply of good quality water, has been forced to depend on ground water of notoriously poor quality. The purpose of this paper is to show how the limitation of available good quality water and the need to use brackish water affects agricultural practices and industrial development in the Safford Valley.

No description available.

The Lawrence Livermore National Laboratory (LLNL), in Berkley, California, developed a laboratory scale non-membrane electrosorption process known as Capacitive Deionization Technology™ (CDT™) for the continuous removal of ionic impurities in water. A saline solution flows through an unrestricted capacitor type module consisting of numerous pairs of high-surface area (carbon-aerogel) electrodes. The electrode material (carbon aerogel) contains a high specific surface area (400 – 1 100 m2/g), and a very low electrical resistivety (< 40 m<font face="symbol">W</font>.cm). Anions and cations in solution are electrosorbed by the electric field upon polarization of each electrode pair by a direct current (1,4 Volt DC) power source. Testing conducted on a laboratory scale unit at LLNL has proved that CDT™ has the potential to be an alternative desalination technology (Farmer5 et al., 1995). The primary objective of this research was to continue, where the laboratory scale research ended. Thus taking CDT™ from a laboratory scale technology to an industrial scale process, by developing and evaluating an industrial CDT™ prototype system. First, a process was developed to manufacture a cost effective industrial sized CDT™ module. During this process various manufacturing techniques were evaluated to produce an optimum prototype. As part of the developmental process the prototype was tested and water treatment efficiency results were first compared to results obtained on the laboratory scale module and secondly to established desalination technologies like reverse osmosis, electrodialysis, and distillation. Due to the wide variety of potential saline feed water sources, research for this dissertation focused on brackish water applications (which includes wastewater reuse applications). After establishing a cost effective small-scale model of a potential industrial manufacturing process, the prototype was tested with regard to water treatment efficiency. Test results on brackish type waters (1 000 mg/l), indicated that the industrial CDT™ prototype had an energy requirement of 0,594 kWh/1000 liters. Research results compared well to the laboratory scale energy consumptions of 0,1 kWh/1000 liters (Farmer5 et al, 1995) and to the best available existing brackish water membrane based desalination systems with energy requirements of 1,3 to 2,03 kWh/1 000 liters (AWWA, 1999). The thermodynamic minimum energy required (due to osmotic pressure) to desalinate a 0,1% or 1 000 mg/l sodium chloride solution, is 0,0234 kWh/1 000 liters. Development and evaluation results indicated that CDT™ industrial modules could be manufactured cost effectively on a large scale and that such units have the potential to be very competitive with existing technologies with regards to overall operational and maintenance costs. Therefore Capacitive Deionization Technology™ can be viewed as a potential alternative to membrane technologies in the future. Regardless of the benefits to the potable water industry, CDT™ have the potential to incur a dramatic step reduction in the operational costs of desalination plants, which will make desalination a more viable alternative technology for large-scale agricultural and industrial uses. / Dissertation (MEng (Waterutilization))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

Yes / The Reverse Osmosis (RO) process has been expansively used in water treatment as a result of its low energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. Evaluation and minimisation of energy consumption (expressed in kWh/m3 of fresh water production) in a medium-scale spiral wound brackish water RO (BWRO) desalination plant of the Arab Potash Company (APC) are the main aims of this research. The model developed earlier by the authors has been integrated to simulate the process and achieve the main aims. Energy consumption calculations of low salinity BWRO desalination plant, with and without an energy recovery device, have been carried out using the gPROMS software suite. In other words, this research evaluated the impact of adding an energy recovery device on the RO process energy consumption of the APC, which is introduced for the first time. Also, the effects of several operating conditions of BWRO process include the feed flow rate, pressure and temperature on the performance indicators, which include the energy consumption and total plant recovery at different energy recovery device efficiencies, were studied. The simulation results showed that the total energy consumption could be reduced at low values of feed flow rates and pressures and high values of temperatures. More importantly, there is an opportunity to reduce the total energy consumption between 47% and 53.8% compared to the one calculated for the original design without an energy recovery device.

Approximately 35% of the population of the Navajo Nation does not have direct access to the electric grid and public water supply. Tribal members haul their potable and livestock water from public water systems that are located great distances from their homes. The Navajo Nation Solar Desalination Research Pilot Demonstration Project is designed to provide residents affordable livestock water. The same technology can later be adopted to provide potable water. The project has deployed an off-grid, prototype water purification unit at a demonstration site north of Leupp, AZ utilizing membrane distillation (MD) technology. A second prototype for the same purposes utilizing nanofiltration (NF) membrane technology has been designed, built, and operated at The University of Arizona. Through experimentation I confirmed information provided the manufacturer of the NF membrane, calculated the production rate to be 636 gallons per day, and calculated the cost of desalinated water to be $0.003 per gallon. Both systems use solar energy to desalinate brackish ground water and the second prototype will later be deployed at the same site for side-by-side comparison. A critical part of the project is the development of technology transfer methods that will help the community take ownership of the project. To accomplish this goal I have written a comprehensive manual that will be given to the Navajo Department of Water Resources. The demonstration site will act as an applied research site for investigation, demonstration, and training related to sustainable water and energy systems designed to address the needs of remote, rural communities in arid and semi-arid regions. The aim is to inform a regional plan for Southwestern Navajo Nation Chapters to address chronic water and energy shortages, demonstrate renewable energy application for water treatment of brackish ground water, evaluate trade-offs in energy and water supplies, and foster community development. The research and demonstration site has been developed by an interdisciplinary and collaborative effort between the Bureau of Reclamation, Apex Applied Technology, Inc., and The University of Arizona.

As freshwater resources are limited and stressed, and as the cost of conventional drinking water treatment continues to increase, interest in the development of non-traditional water resources such as desalination and water reuse increases. Reverse osmosis (RO) is the predominant technology employed in inland brackish groundwater desalination in the United States, but the potential for membrane fouling and scaling generally limits the system recovery. The general hypothesis of this research is that electrodialysis (ED) technology can be employed to minimize the volume of concentrate waste from RO treatment of brackish water (BW) and thereby improve the environmental and economic feasibility of inland brackish water desalination. The objective of this research was to investigate the performance sensitivity and limitations of ED for treating BWRO concentrate waste through careful experimental and mathematical analysis of selected electrical, hydraulic, and chemical ED variables. Experimental evaluation was performed using a laboratory-scale batch-recycle ED system in which the effects of electrical, hydraulic, and chemical variations were observed. The ED stack voltage showed the greatest control over the rate of ionic separation, and the specific energy invested in the separation was approximately proportional to the applied voltage and equivalent concentration separated. An increase in the superficial velocity showed marginal improvements in the rate of separation by decreasing the thickness of the membrane diffusion boundary layers. A small decrease in the nominal recovery was observed because of water transport by osmosis and electroosmosis. Successive concentration of the concentrate by multiple ED stages demonstrated that the recovery of BWRO concentrate could significantly improve the overall recovery of inland BWRO systems. A mathematical model for the steady-state performance of an ED stack was developed to simulate the treatment of BWRO concentrates by accounting for variation of supersaturated multicomponent solution properties. A time-dependent model was developed that incorporated the steady-state ED model to simulate the batch-recycle experimentation. Comparison of the electrical losses revealed that the electrical resistance of the ion exchange membranes becomes more significant with increasing solution salinity. Also, a simple economic model demonstrated that ED could feasibly be employed, especially for zero-liquid discharge. / text

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references.