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This thesis investigates the viability of a solar still for desalination of a personal water supply. The end goal of the project is to create a design that meets the output requirement while tailoring the components to focus on low cost so it would be feasible in the impoverished areas

This thesis investigates the viability of a solar still for desalination of a personal water supply. The end goal of the project is to create a design that meets the output requirement while tailoring the components to focus on low cost so it would be feasible in the impoverished areas of the world. The primary requirement is an output of 3 liters of potable water per day, the minimum necessary for an adult human. The study examines the effect of several design parameters, such as the basin material, basin thickness, starting water depth, basin dimensions, cover material, cover angle, and cover thickness. A model for the performance of a solar still was created in MATLAB to simulate the system's behavior and sensitivity to these parameters. An instrumented prototype solar still demonstrated viability of the concept and provided data for validation of the MATLAB model.
ContributorsRasmussen, Dylan James (Author) / Wells, Valana (Thesis director) / Trimble, Steven (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
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This dissertation investigates the mechanisms that lead to fouling, as well as how an understanding of how these mechanisms can be leveraged to mitigate fouling.

To limit fouling on feed spacers, various coatings were applied. The results showed silver-coated biocidal spacers outperformed other spacers by all measures. The control polypropylene

This dissertation investigates the mechanisms that lead to fouling, as well as how an understanding of how these mechanisms can be leveraged to mitigate fouling.

To limit fouling on feed spacers, various coatings were applied. The results showed silver-coated biocidal spacers outperformed other spacers by all measures. The control polypropylene spacers performed in-line with, or better than, the other coatings. Polypropylene’s relative anti-adhesiveness is due to its surface free energy (SFE; 30.0 +/- 2.8 mN/m), which, according to previously generated models, is near the ideal SFE for resisting adhesion of bacteria and organics (~25 mN/m).

Previous research has indicated that electrochemical surfaces can be used to remove biofilms. To better elucidate the conditions and kinetics of biofilm removal, optical coherence tomography microscopy was used to visualize the biofouling and subsequent cleaning of the surface. The 50.0 mA cm-2 and 87.5 mA cm-2 current densities proved most effective in removing the biofilm. The 50.0 mA cm-2 condition offers the best balance between performance and energy use for anodic operation.

To test the potential to incorporate electrochemical coatings into infrastructure, membranes were coated with carbon nanotubes (CNTs), rendering the membranes electrochemically active. These membranes were biofouled and subsequently cleaned via electrochemical reactions. P. aeruginosa was given 72h to develop a biofilm on the CNT-coated membranes in a synthetic medium simulating desalination brines. Cathodic reactions, which generate H2 gas, produce vigorous bubbling at a current density of 12.5 mA cm-2 and higher, leading to a rapid and complete displacement of the biofilm from the CNT-functionalized membrane surface. In comparison, anodic reactions were unable to disperse the biofilms from the surface at similar current densities.

The scaling behavior of a nanophotonics-enabled solar membrane distillation (NESMD) system was investigated. The results showed the NESMD system to be resistant to scaling. The system operated without any decline in flux up to concentrations 6x higher than the initial salt concentration (8,439 mg/L), whereas in traditional membrane distillation (MD), flux essentially stopped at a salt concentration factor of 2x. Microscope and analytical analyses showed more fouling on the membranes from the MD system.
ContributorsRice, Douglas, Ph.D (Author) / Perreault, Francois (Thesis advisor) / Abbaszadegan, Morteza (Committee member) / Fox, Peter (Committee member) / Lind-Thomas, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2019