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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis of a triblock polymer system for separation of actinides for nuclear waste remediation

Hamilton, Doris Finley 06 January 2011 (has links)
Nuclear power waste contains radioactive isotopes with long half lives and the problem lies in the fact that the lanthanides and actinides must be separated before the nuclear waste can be reprocessed. Transuranic Extraction (TRUEX), a liquid-liquid extraction method, has been developed but fails to separate the lanthanide and actinides and creates large volumes of liquid waste. It has been shown that attaching three CMPO (carbamoyl phosphine oxide) ligands used in the TRUEX process to a calixarene increases the separation and extraction efficiency of the system. The research goal is to attach the CMPO ligand to a polymer to make a membrane to be used in nuclear waste remediation. The triblock polymer system has been designed to have a cross-linking group to create the membrane structure, a solubilizing group to improve the flow of aqueous media through the membrane, and the CMPO ligand to chelate actinides. This paper describes the design of the polymer, its synthesis, and my research data. / text
2

Nutrient Utilization from Anaerobic Digester Effluent Through Algae Cultivation

Wahal, Shantanu 01 May 2010 (has links)
Nutrients present in digested animal waste can be utilized for algae cultivation under suitable conditions. Algal growth, however, depends on the chemical forms and speciation of these nutrients. In this study a chemical equilibrium model was first used to describe nutrient speciation and predict conditions that enhance the solubility of nutrients in anaerobic digester effluent. Dilution with water and separation of large particulates greatly improved nutrient availability and light penetration - conditions favorable for algal cultivation. Algae growth was tested using three strains - Scenedesmus dimorphous (UTEX # 417), Chlorella vulgaris (UTEX# 265), and an algal isolate (designated as LLAI and later identified to be closely related to Chlorella vulgaris) from the wastewater treatment lagoons in Logan, UT. All tested strains could be adapted to the effluent to enhance the utilization of native nutrients present in both organic and inorganic forms. There was a marked improvement in growth rates (up to 4.8-fold) and biomass production (up to 8.7-fold) of algal cultures after they adapted to the effluent. Also, effluent-adapted strains were able to switch from phototrophy to heterotrophy to prolong the growth when light availability became limited. However, an increase in irradiance levels in light-limited cultures led to resumption of phototrophic growth. It was found that this approach of light supplementation prolonged growth and increased biomass production (up to 2.7-fold) in algal cultures. Of all the strains tested, the isolate from the wastewater treating lagoons grew to highest culture densities and produced the highest concentration of intracellular triacylglycerides (TAG). This culture also grew best in non-sterile, native effluent and could reach biomass concentration of up to 4.5g/L with TAG content of approximately 10% (w/w). Culture densities were lower when this organism was grown in sterilized effluent or in sterile artificial media, suggesting that this organism symbiotically associated with other microbes in digested animal waste. Findings of this research study suggest that microalgae can be grown efficiently on inexpensive natural substrates in non-sterile growth conditions. When commercially implemented, biodiesel production from such systems could be more cost effective and sustainable.

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