Thesis (M.S.)--University of Nevada, Reno, 2007. / "December, 2007." Includes bibliographical references (leaves 207-215). Online version available on the World Wide Web.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 232 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 210-225).

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Made available in DSpace on 2014-10-09T12:54:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:12Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:54:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:12Z (GMT). No. of bitstreams: 0 / As cinzas de carvão podem ser convertidas em produtos zeolíticos por tratamento hidrotérmico alcalino. No presente estudo, a capacidade de zeólitas sintetizadas a partir de cinzas de carvão brasileiras (6 amostras da cinza volante do filtro de mangas e 6 amostras da cinza leve do filtro ciclone) na remoção de Zn2+ e Cd2+ de soluções aquosas foi investigada. O tempo de equilíbrio alcançado pela maioria das zeólitas foi de 24 horas. Os dados de equilíbrio obtidos se ajustaram à isoterma de adsorção de Langmuir. As capacidades de troca catiônica máximas estavam entre 25,9 e 39,5 mg g-1 para o Zn2+ e entre 49,5 e 72,3 mg g-1 para o Cd2+. A zeólita sintética (ZM1) apresentou área superficial no valor de 66,38 m2 g-1, baixa relação Si/Al (1,65) e a formação de zeólitas sodalita e faujasita, que contribuíram para seu melhor desempenho. Estudos de adsorção de íons metálicos com a ZM1 indicaram a seguinte seqüência de seletividade: Pb2+ > Cd2+ > Cu2+ > Zn2+ > Ni2+. Para a ZM1, a maior porcentagem de remoção de Zn2+ e Cd2+ foi obtida em pH 5 e a recuperação de metais foi efetivamente realizada com solução de NaCl 2 mol L-1. Comparou-se o desempenho das zeólitas sintetizadas a partir das cinzas de carvão com as zeólitas sintéticas comerciais, bem como o custo de ambas. As zeólitas sintetizadas com cinza de carvão apresentaram melhor eficiência de retenção do zinco e do cádmio do que as zeólitas comerciais. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

High F- groundwaters occur in various parts of South Africa, namely, the larger part of the Karoo, Limpopo, North West and Northern Cape Provinces. The use of these waters for drinking purposes on continual basis can lead to fluorosis. Fluorosis is a debilitating disease caused by drinking water with F- concentrations higher than ca. 1 mg.L-1. The disease is characterized by mottled teeth in dental fluorosis and brittle bones in severe skeletal fluorosis. Solution to this problem involves the implementation of a method for F- removal from water. Defluoridation has become a widely practiced process worldwide due to the problem of fluorosis caused by the presence of F- in drinking waters. Methods such as adsorption, precipitation, ion exchange and membrane processes have been employed for F- removal. Adsorption techniques, in particular using activated alumina have proven successful in removing F- from water. However, this method can not always be used in rural areas because of high costs and technical requirements. In this study, locally available clays were studied as potential substrates for F- removal from water. The first part of the study focused on the explanation of mechanisms and the development of an adsorption model. The exchange of OH- by F- in the clay structure is the principal mechanism that takes place during adsorption. The change in pH during this exchange process was studied to support and verify the fluoride-hydroxide exchange mechanism. In the second part of the study, locally available South African clays were studied as possible adsorbents for F- removal from water. Clays containing aluminium and iron oxide surfaces proved to be useful substrates for F- adsorption. The adsorption of F- onto clay samples was found to be pH dependent. Maximum adsorption was achieved at pH 5 for aluminium oxide type sorbents and pH 4 for iron oxides types such as goethite. The effect of physical and chemical pretreatment improved the adsorption capacity of some clays. Coating clay samples with aluminium and iron oxides enhanced the adsorption capacity of clays. The last part of the study involves the development of a cost-effective and quick way to assess the performance of clays as adsorbents for F- removal using laboratory scale defluoridation columns. / Prof. P.P. Coetzee

This dissertation addresses the relationship between large-scale dam removal and the nearshore ecosystem function for fish. The work is based on almost a decade’s worth of collaborative field work in the nearshore of the largest dam removal in the world recently completed on the Elwha River. The data analyzed span seven years prior to, during, and throughout the first year of each dam removal (January 2008 to November 2015). As of September 2015, approximately 2.6 million m3 of sediment material increased the area of the Elwha delta to over 150 ha. Long term study of fish in the estuary reveals fish community response to dam removal, and indicates likely interactions in the nearshore between hatchery and wild fish, including chum salmon critical to watershed recovery. Continued hatchery releases may therefore further challenge chum salmon recovery, and this interaction should be considered when planning for future watershed recovery. Community analysis revealed that, while species richness and taxonomic diversity do not appear to have a significant response to dam removal, functional diversity in the nearshore does respond significantly to dam removal. Three main shifts occurred in the nearshore: large scale and rapid creation of estuary habitats; delivery of large amounts of sediment to the delta/estuary in a short period of time, and; a shift in original habitats from tidally influenced to non-tidally influenced habitats resulted in changes in estuary function. Changes in functional diversity occur disproportionately in the new sites, which have more unstable, and so less resilient, communities. Functional diversity in the original estuary sites appears to be more resilient than in the newly created sites due to the large-scale environmental disruption that, ironically, created the new sites. However, the functional diversity at the original sites may be defined in part by management activities, including hatcheries that could mute/mask/inhibit other community responses. Further, functional diversity at the newly formed nearshore areas is predicted to stabilize as the habitats are vegetated and mature. Principal components analysis of Elwha fish community over the course of this study reveals that the fish communities of the Elwha are predictably grouped, indicating that while a few new species are observed, dam removal has not resulted in observable disruptions in fish community assemblages. And finally, nearshore habitats are critical for many forage fish species, and an emerging topic for large-scale dam removals. Forage fish spawning response to dam removal appears to be complex and may be related to multiple factors including high interannual variability in physical habitat conditions, geographic factors and complex life histories of forage fish. Habitat suitability for forage fish spawning should increase as restored ecosystem processes and newly created habitats mature and stabilize, indicating that time may be an important factor in nearshore restoration for forage fish spawning. It is therefore important to implement long-term monitoring and incorporate nearshore ecosystem process and function for multiple life history stages of nearshore species, including forage fish, into large-scale dam removal restoration and management planning. / Graduate / 2019-04-12

Mercury (Hg) is distributed globally through atmospheric transport. The broad range of environmental conditions will lead to various possible speciation of mercury, which will ultimately affect the toxicity and transport of mercury. Hg toxicity, transport and speciation have been widely studied. However, information about effects of Hg speciation on its environmental behavior in unsaturated porous media and on its removal from wastewater stream is still limited. The present work contributes towards understanding the impact of Hg speciation on both the transport of Hg species in unsaturated porous media (e.g., surface soil) and removal of Hg species in wastewater streams. This knowledge is necessary to assess the possible environmental risks of Hg in the environment, where different Hg species can exist and have different properties and impacts on water quality and ecosystems. The first objective of this research was to determine the effect of Hg speciation on its retention in partially saturated soils. The retention of Hg species in model porous media and in real soil was assessed in column breakthrough experiments. Deposition (retention) rates for each Hg species were calculated to evaluate the influence of Hg speciation, porous medium composition and influent solution on the mobility of Hg species in porous media. This study provided information about the relative retention of each Hg species in soils, and identified natural-organic-matter-bound Hg as the most mobile Hg species and that with the greatest potential for vertical migration to groundwater. The second objective of this research was to determine how Hg speciation affects its ability to be removed from water via adsorption by activated carbon and organoclay. The effects of Hg speciation, water quality parameters and adsorbent type on the removal of Hg were compared to explore the potential removal efficacy and mechanism. The result indicated Hg removal efficacy was influenced by Hg speciation differently depending on the solution conditions. Therefore, using total dissolved Hg(II) to predict Hg removal efficacy may not provide a reliable estimate of adsorption. Organoclay was shown to have a highly reactive surface and the highest adsorption capacity per unit specific surface area among the tested adsorbents. The third objective was to determine the Hg speciation in produced water from an oil production well, and to study the influence of Hg speciation on its removal from produced water by adsorbents. Mercury species in a produced water sample were identified as mainly particulate species and hydrophobic species. The removal of the amended Hg species in produced water was measured to evaluate the impact of Hg speciation on its removal. This study showed that produced water composition affected Hg speciation and formed hydrophobic Hg was more difficult to remove than initially added hydrophilic Hg species in produced water.

M.Sc. / The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. Both organic and inorganic contaminants (especially heavy metals) pollutants are often present in water distribution networks. Organic and inorganic pollutants often co-occur in drinking water networks. However, at present there is no water treatment intervention that simultaneously removes organic and inorganic pollutants from water. Additionally, current water treatment technologies fail to remove these contaminants to parts per billion (ppb or µg.L-1) levels. Methods that can simultaneously remove organic and inorganic pollutants to desired levels need to be developed. In our laboratories, both functionalised and unfunctionalised cyclodextrin (CD) polymers have demonstrated the ability to effectively remove organic species from water at low (ppb) concentrations. Cyclodextrins (CDs), which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4-glycosidic linkages, behave like molecular hosts. They are capable of interacting with a range of guest molecules within their cylindrical hydrophobic cavities thereby forming the so-called inclusion complexes. Their solubility in water, however, precludes their application in the removal of organic pollutants from water. This limitation is easily dealt with by polymerizing the CDs into water insoluble polymers with suitable bifunctional linkers. On the other hand, ionic liquids (ILs) have been reported to “absorb” heavy metal ions from aqueous media. ILs are low melting point molten salts that are composed of organic cations (e.g. imidazolium and pyridinium ions) and mostly inorganic anions like Cl–, Br–, [PF6]– and [BF4]–. In this study, the two systems were combined by an initial attachment of the imidazolium or pyridinium rings to the cyclodextrin moiety. Polymerisation of the resulting cyclodextrin-ionic liquid (CD-IL) complexes with a suitable linker produced the corresponding water insoluble CD-IL polymers. This dual system has shown excellent capabilities for the removal of model pollutants such as p-nitrophenol (PNP) and 2,4,6-trichlorophenol (TCP) and chromium (Cr6+) from aqueous media. However, the CD-IL polymers showed very little affinity for the absorption of cadmium from water. TGA and DSC studies showed that these polymers are stable over a wide range of temperatures (100-400 C).

The contamination of water by organic compounds has resulted in an escalation in research efforts to combat this problem. These organics can be harmful to human health and the environment in general, and they pose unique challenges to several industrial applications. Even when present at very low concentrations, they tend to bioaccumulate and interact with endocrine systems. However, due to the chemical nature of these compounds, current technologies are still challenged to effect their removal from water. Of currently used technologies, activated carbon and reverse osmosis can remove most of the organic pollutants but fail to remove them to very low concentrations (ng/L levels). Recent studies have explored the capabilities of nanoporous cyclodextrin (CD) polymers, a class of nanomaterials that show great potential to absorb organic contaminants from water. The project reported in this dissertation was undertaken to further explore the efficacy of these polymers in order to assist industries and municipalities in their quest to solve the problem of water contamination by organic species. The ability of these polymers to remove selected organic contaminants from water at varying concentrations was studied. The investigated pollutants were chlorinated disinfection by-products (DBPs), taste and odour causing compounds (geosmin and 2-methylisoborneol) and humic acid, which was used to mimic natural organic matter (NOM). Water samples were pre-concentrated using solid phase extraction (SPE) and subsequently quantified by Gas Chromatography-Mass Spectrometry (GC/MS). The CD polymers demonstrated absolute efficiency at quenching organics at very low concentrations compared to granular activated carbon (GAC). The recyclability efficiency of the CD polymers was also investigated. Most of the work was carried out using rapid small scale column tests (RSSCTs) that were designed in our laboratories. The general design of the study and pathway that was followed while conducting these experiments is shown in the flow diagram on the next page. / Dr. B.B. Mamba