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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

Remote community drinking water supply : mechanisms of uranium retention and adsorption by ultrafiltration, nanofiltration and reverse osmosis

Schulte-Herbruggen, Helfrid Maria Albertina January 2012 (has links)
Worldwide, around 884 million people lack access to safe drinking water. To address this, groundwater sources such as boreholes and wells are often installed in remote locations especially in developing countries. However, the natural chemical composition of groundwater may be a source of toxicity to human health. Uranium is naturally present in the environment, and concentrations above the World Health Organisation (WHO) drinking water guideline (15 μg/L) are found in various parts of the world. Uranium has a complex aqueous chemistry and its speciation, which varies according to pH and available ligands, determines its behaviour (e.g. mobility, reactivity or sorption tendency). Nanofiltration and reverse osmosis have proved effective in removing uranium from water, although fundamental removal mechanisms are not well understood. Even the more porous ultrafiltration (UF) has been shown to remove uranium when used in combination with complexation/coagulation methods. To address the water purification needs of remotely located communities with no or unreliable access to energy, a renewable energy powered membrane system was designed using UF as pre-treatment to remove particles, bacteria and viruses and NF/RO to remove ions. The system was trialled in the Australian outback, using natural groundwater high in uranium (>300 μg/L). Results showed that pH had a large effect on the uranium behaviour in the system and, curiously, interaction by sorption or precipitation to the membranes was observed at certain pH values. However, due to the complexity of the water and the combination of UF and NF/RO membranes, the mechanisms of the uranium retention and interaction with the membrane were not clear. Further systematic study was needed to investigate the uranium behaviour with the membranes. Laboratory studies were carried out with one membrane type at a time: UF, NF and RO. It was postulated that pH, organic matter and inorganic ions such as calcium have an important influence on uranium retention and interaction with membranes. Results show that uranium behaviour in the membrane systems was highly pH dependent. During the UF experiments, increased adsorption of uranium occurred in uranium-only solutions at pH 5-7. From the UF experiments with organic matter it could be concluded that organic matter did not increase retention (size exclusion) of uranium, however it did increase the adsorption. Humic acid increased adsorption to 80-95% at pH 3-5, alginic acid at pH 3 while tannic acid caused a nearly 100% adsorption at pH 10-11. Further investigating uranium behaviour with NF and RO membranes, it was found that uranium showed the same increase in affinity to the membrane at pH 5-7, with about 50% being taken up by NF and 30% by RO membranes. The effect of pressure on uranium-membrane interaction was investigated for NF and RO at pH 6 and 8.5. Pressure and consequent concentration polarisation only increased uranium affinity to the NF membrane at pH 8.5 where the uranium species and MWCO of the membrane were similar. There was no or little effect of pressure on the affinity of uranium to the NF membrane at pH 6 or to the RO membrane. At pH 6, STEM-EDX results showed that uranium was distributed through-out the polyamide active layer of the NF membrane while FTIR results confirmed that uranium bound to carboxyl groups in the polyamide. At pH 8.5 however, FTIR results showed that uranium did not form chemical bonds with the membrane, but was rather attracted to the surface through hydrogen bonding and loosely forming a layer on top of the membrane visible in SEM. It was concluded that at least three different characteristics of the uranium species and membranes played a role for the interaction: 1) uranium species valency and membrane charge, 2) uranium species size relative to the membrane pore size, and 3) the reactivity of the uranium species towards the membrane functional groups. The effect of calcium on uranium retention and uranium-membrane interaction in NF and RO was also investigated. Calcium affects uranium speciation by forming a neutral complex with uranium at pH 8-9, causing a decrease in adsorption to the membrane. Calcium also precipitates at pH 10. SEM and TEM images showed that the precipitation of calcium carbonate (CaCO3) as calcite caused co-precipitation of uranium, trapping it on the surface of the membrane. About 48-55% of the calcium precipitated which caused a 26-35% co-precipitation of uranium, compared to <5% adsorption in the absence of calcium at pH 10. Finally the chemical drinking water quality of mainly boreholes and wells across a West African country, Ghana, was investigated (199 samples in total from “improved” sources). In addition, the user water costs were documented and the scope for advanced treatment explored. The WHO guidelines for chemical water quality were exceeded in 38% of the samples. The main contaminants were nitrate (21%), managanese (11%) and fluoride (7%), while heavy metals such as lead, arsenic and uranium were localised to mining areas. It was concluded that when taking the cost of unsuccessful borehole development into account, alternative treatment may be a suitable option where inorganic contamination is high. The findings from this study show the importance of the water quality conditions (pH, organic matter and calcium) on the behaviour of contaminants such as uranium in membrane systems and explain the mechanisms of adsorption and co-precipitation of uranium to the membranes at certain pH values. These are important considerations when selecting appropriate membranes for water treatment and also for the maintenance of membranes. The study also showed that there is need for advanced treatment of drinking water in e.g. Ghana, but highlights the importance of strategies on local and national level to ensure long-term sustainability and integration of any such treatment.
2

A BOTTOM UP APPROACH TO EVALUATE RISK ASSESSMENT TOOLS FOR DRINKING WATER SAFETY IN FIRST NATIONS COMMUNITIES

Levangie, Janice Catherine 05 October 2009 (has links)
Safe drinking water is a basic need; and risk assessment tools may assist in prioritizing actions to improve water safety. The objective of this research was to determine the appropriateness of current risk assessment approaches for First Nations drinking water systems. Criteria to evaluate risk assessment approaches were developed by combining common elements from literature, key informant interviews, and surveys. The criteria were compared against selected tools for drinking water risk assessment, including tools developed by Australia, Montana, Indian and Northern Affairs, and the University of Guelph. None of the tools, as available, met all of the criteria. Important considerations were found to include the operator, monitoring and recordkeeping, maintenance, technical considerations, emergency response plans, and source water protection. The tools were generally weak in assessing some potential challenges facing small, remote, and First Nations communities; including financial constraints, and taking a holistic view of water. / Note: this thesis was also submitted in hard-copy to Graduate Services
3

Holistic and integrated energy system optimization in reducing diesel dependence of Canadian remote Arctic communities

Quitoras, Marvin Rhey D. 17 September 2020 (has links)
This dissertation demonstrates novel holistic approaches on how to link policy, clean energy innovations, and robust energy modeling techniques to help build more resilient and cost-effective energy systems for the Canadian Arctic region and remote communities in general. In spite of the diversity among Arctic jurisdictions, various energy issues and challenges are shared pan-territorially in the North. For instance, 53 out of 80 remote communities in the Northern territories rely exclusively on diesel-based infrastructures to generate electricity, with heating oil as their primary source of heat. This critical dependence on fossil fuels exposes the Indigenous peoples and other Canadians living in the North to high energy costs and environmental vulnerabilities which is exacerbated by the local and global catastrophic effects of climate change in the Arctic. Aside from being strong point sources of greenhouse gases and other airborne pollutants, this reliance on carbon-intensive sources of energy elevates risk of oils spills during fuel transport and storage. Further, conventional transportation mode via ice roads is now increasingly unreliable because of the rising Arctic temperatures which is twice the global average rate. As a result, most fuels are being transported by small planes which contribute to high energy costs and fuel poverty rates, or via boats which also increases the risk of oil spills in the Arctic waters. Methodologically, this thesis presents a multi-domain perspective on how to accelerate energy transitions among Northern remote communities. In particular, a multi-objective optimization energy model was developed in order to capture complex trade-offs in designing integrated electrical and thermal energy systems. In comparison with traditional single-objective optimization approach, this technique offers diversity of solutions to represent multiple energy solution philosophies from various stakeholders and practitioners in the North. A case study in the Northernmost community of the Northwest Territories demonstrates the applicability of this framework - from modeling a range of energy solutions (supply and demand side aspects) to exploring insights and recommendations while taking into account uncertainties. Overall, this dissertation makes a set of contributions, including: (i) Development of a robust energy modeling framework that integrates complex trade-offs and multiple overlapping uncertainties in designing energy systems for the Arctic and remote communities in general; (ii) Extension of previous Arctic studies - where focused has solely been on the electricity sector - by integrating heating technology options in the proposed modeling framework in conjunction with methods on obtaining `high performance' buildings in the North; (iii) Overall energy system performance evaluation when integrating heat and electricity sectors, as well as the role of battery storage systems and diesel generator on facilitating variable renewable energy generation among isolated communities; (iv) Formulation of a community-scale energy trilemma index model which helps design policies that are accelerating (or hindering) energy transitions among remote communities by assessing quantitatively challenges relating to energy security, affordability, and environmental sustainability; (v) Synthesized holistic insights and recommendations on how to create opportunities for Indigenous peoples-led energy projects while discussing interwoven links between energy system operations, relationship building and stakeholders engagement, policy design, and research (energy modeling and analysis). Collectively, the new methods and recommendations demonstrated herein offer evidence-based decision making and innovative solutions for policy makers, utility companies, Indigenous peoples, and other stakeholders in the Arctic and beyond. / Graduate
4

Teens Vs. Tech: Using an Asynchronous Remote Community Environment to Explore Adolescents' Online Safety Perspectives

Jean Baptiste, Naulsberry 01 January 2023 (has links) (PDF)
Due to the continuous use and rise of social media sites among teens and worries about their safety while using these sites, Human-Computer Interaction (HCI) researchers have been working together with teenagers using methods such as participatory design/co-design to study their social media usage, along with the risks they encounter and their behavior online. However, this comes with several constraints such as power imbalances, conflicting schedules of teenagers, and lack of attendance. To work towards engaging teens in online safety research without being bound by these constraints, we recruited 7 teens between the ages of 15-17 years old to be a part of a year-long Youth Advisory Board (YAB) for the Socio-Technical Interaction Research (STIR) Lab. We conducted online activities with the teen participants in our YAB within an Asynchronous Remote Community (ARC), which is an online group where communication and activity participation occur asynchronously between researchers and participants. To collect our data, we first organized a synchronous Zoom meeting with the teens about the ARC research method, discussed how the method relates to them, and talked about the topics and activities that they would like to partake in within an ARC. Then, we conducted activities with the teens to discuss their social media usage and their perceptions of algorithms used to provide content on social media. Our participants were interested in discussing topics that were related to safety on social media platforms and doing research activities that could best be implemented through the ARC research method such as giving feedback on research design, suggesting solutions to online safety prompts, and designing apps based on an online safety prompt. We also found that our participants' social media platform usage heavily depended on their goals as users, and they were weighing the privacy affordances and risks that came with using the platforms to decide which platform is best for their goals. Finally, our teen participants were aware of the positive and negative impacts that algorithms on social media platforms have on their online safety. They were skeptical of social platform algorithms due to their safety and privacy concerns, though they understood the benefits and wanted to learn more about how these algorithms operate. Overall, our participants appreciated the ARC methodology for exploring online safety perspectives, as it does allow them enough time to take part in activities and collaborate in discussions with each other. Our findings suggest that ARC can be an effective method for co-designing research studies to understand teens' social media usage, the risks they encounter online, and ways to mitigate such risks on social media.
5

Resistência bacteriana a antimicrobianos em uma comunidade remota da Floresta  Amazônica. / Antimicrobial resistance in a remote community in the Amazon Forest.

Silva, Quézia Moura da 14 June 2017 (has links)
O objetivo deste trabalho foi investigar a presença de bactérias produtoras de &#946;-lactamases adquiridas na microbiota Gram-negativa comensal de humanos e animais domésticos em uma comunidade remota na região da Floresta Amazônica. De março a julho de 2013 foram coletadas amostras de fezes de indivíduos atendidos e funcionários de um centro assistencial em saúde restrito a comunidades indígenas e de swab retal de animais de companhia da comunidade. Nas amostras de humanos foram detectados isolados de Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter kobei e Morganella morganii, carregando os genes blaTEM-1, blaCTX-M-15, blaCTX-M-14, blaCTX-M-8 e blaGES-5. Nas amostras de animais foram detectados apenas isolados de E. coli carregando os genes blaTEM-1, blaCTX-M-14, blaCTX-M-2 e blaCTX-M-8. Foi observada a relação clonal entre isolados de E. coli de origem humana e de origem animal. Estes resultados demonstram a disseminação de um problema endêmico em áreas urbanas para uma comunidade, em teoria, com baixa exposição a antibacterianos. / The aim of this study was to investigate the presence of acquired &#946;-lactamase in the commensal Gram-negative microbiota of humans and domestic animals of a remote community in the Amazon Forest region. From March to July 2013 stool samples were collected from individuals attended in a health care center restricted to indigenous communities and from the local staff, and rectal swab samples were collected from companion animals in the community. In the human samples were detected Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter kobei and Morganella morganii isolates harboring blaTEM-1, blaCTX-M-15, blaCTX-M-14, blaCTX-M-8 e blaGES-5 genes. In the animal samples only E. coli strains harboring blaTEM-1, blaCTX-M-14, blaCTX-M-2 and blaCTX-M-8 were detected. The clonal relatedness between E. coli strains from human and animal samples was observed. These results demonstrate the dissemination of an urban endemic problem to a community, in theory, with low antimicrobial exposure.
6

Action research in preventing workplace burnout in rural remote community mental health nursing.

Petrie, Eileen Margaret January 2008 (has links)
The social phenomenon of stress and workplace burnout has spanned over five decades. Despite a plethora of literature that exists, there still remain problematic issues that neither scientific investigation or government legislation have been able to resolve. The literature examined throughout this research is extensive and does reflect this 50-year period. It demonstrates that studies into this phenomenon have attempted to define stress, identify causal factors of workplace stress, workplace burnout and environmental congruence; and discusses strategies (focused on both the individual and organizational levels) that have been implemented to effect beneficial outcomes for individuals affected by any one of these. As this thesis continues, the more recent literature gives a greater recognition to violence in the workplace and legislative enactments as preventative measures to reduce the heavy burden of costs, both physical and financial, to organizations. This extensive literature review indicates no answer to the problem has been identified to date and that this phenomenon remains, giving a clear indication that further scientific investigation is required to find a solution to what was described as the most serious health issue of the 20th century. Based on the literature examined this health issue has now gone well beyond the 20th century, giving relevance to the research study described in this thesis. The investigation is validated as vital and should be used as a basis for further research. This study undertook a collaborative social process, action research, empowering participants to identify and change stressful factors identified within their practice indicative to rural remote community mental health teams. A critical social theory arose out of the problems within the context of the research setting, based on the ideal that the significant issues for this group of individuals within this organization could be solved through the action research process. The group ‘existed’ within the issues indicative to this rural remote area, however these issues were outside their control. Through the implementation of the action research process courses of actions were undertaken that provided enlightenment in self-knowledge with dialogue heightening collective empowerment to effect change within their practice. The action research process, being a holistic process, facilitated this change in practice, developed and refined theory as it proceeded in a cyclic fashion within this local setting. It concerned actual not abstract practices in the social world in which these participants practice. This methodology facilitated examining the significant stressors identified by the Community Mental Health Support Team (CMHST) that caused distress, allowing them to implement changes in their practice. The forum provided an avenue that could reduce stressors significantly and prevent ongoing occupational stress that contributes to workplace burnout. It offered an opportunity to work with a group of participants in a nonhierarchical and non-exploitative manner and enabled members of this group to identify their roles as effective practitioners, empowering them to effect the changes they deemed as essential criteria to reduce the stress they were experiencing indicative to their remoteness. Critical reviewing throughout the data collection attempted to understand and redefine these significant issues. It aimed to acknowledge the way things were relative to how things could be improved from organizational, personal and wider community perspectives. Simple principles and guidelines of action research were followed potentiating acceptance as a rigorous research approach from a positivist perspective whilst retaining the attributes that characterise action research. There are solutions to the dilemma of the employee overcoming the debilitating effects of stress leading to workplace burnout. This includes the cooperation of managers, policy makers, academic researchers and government officials working collaboratively to reduce the impact of occupational stress. Through this collaborative process, changes can be effected to ensure the health of the nation improves and that relevant recognition is given to the fact that there is a significant threat to a healthy workforce. Examining the nursing profession from a social perspective provides alternatives to medicalising workplace injuries and illnesses. / Thesis (Ph.D.) - University of Adelaide, School of Population Health and Clinical Practice, 2008

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