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(2023)ThesisThis PhD thesis covers a range of research topics particularly in water and wastewater treatment, copper recovery from a mining company effluent, slime dewatering, drug synthesis, and a fire suppressing material. Pollution of drinking water by toxic heavy metal ions is a matter of concern worldwide. These pollutions may occur naturally or from industrial wastes. Surfactants have been used to remove organic and inorganic contaminants from water. After usage, the residual surfactants are discharged into surface waters or sewage systems. This can cause environmental pollution. In this work, a biodegradable surfactant was synthesised and used to treat contaminated water containing PFAS and heavy metal ions. Moreover, the effectiveness of the synthesised green surfactant was examined through recovery of copper ions presenting in the effluent produced by a mining company located in Australia. To achieve a better result, a pre-treatment phase was applied before the main ion flotation process. The term slime typically refers to a water-based colloidal dispersion that resists dewatering. Dewatering is a process in which water from the slime is separated from the dispersed solids to thicken up the waste for disposal or further processes. In this work, a novel method was developed and studied using a Bubble Column Evaporator (BCE). Based on this method, dewatering was undertaken in sub-boiling conditions using hot air and hot helium bubbling. The obtained results show that this is a promising method for dewatering slimes and using hot helium was found to be more efficient than using hot air. IV N-acetylcysteine is a drug which is used to treat paracetamol overdose. The molecular structure of this drug is similar to the molecular structure of the surfactant which was synthesised in this work for use in ion flotation. Therefore, synthesis of N-acetylcysteine was also studied with this synthesis method. Moreover, a new water-saving method is proposed to extinguish fires. This fire suppressant material, which is based on the use of a zeolite, can release large amounts of carbon dioxide when exposed to raised temperatures. This material can be used in roof cavities to protect properties against fires caused by, for example, electrical faults or ember attacks.
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(2023)ThesisSupramolecular macrocyclic structures such as cucurbiturils, have gained a significant reputation as host molecules capable of encapsulating a number of guest species. Their structural and chemical properties have rendered them useful for applications such as catalysis, molecular switches, drug delivery, etc. These properties and their usefulness for certain applications, can be expanded or enhanced by employing Q[n]s with functionalized substituents. This thesis focuses on derivatization of Q[n] bearing a tetrahydrothiophene (THT) group on an equatorial position, with the potential to bind to nanoparticles (NPs) of gold and silver. Also, equatorial attachment of NPs through the THT group was expected to enable accessibility of the cavity for guest encapsulation. The scope of further functionalization of this group, into thioether and thiol derivatives, for stronger attachment with NPs, was explored in this thesis. For this purpose, model reactions were first designed and tested on THT glycoluril with the objective of applying these reactions to THTQ[n] to obtain target derivatives. The derivatives were obtained after reacting THTQ[n] with diethylene glycol and 2-hydroxyethyl disulfide as reagents, and these derivatives were analyzed using standard techniques. The analysis of the 2nd derivative revealed the presence of additional products together with the expected disulfide derivative. The 2nd part of the thesis was aimed at using the above derivatives to construct NP conjugates that could be used as drug carriers. Gold NP conjugates were synthesized using THTQ[n], and their thioether and diethylene glycol derivatives and their properties studied using TEM and UV-Vis spectroscopy. Purification and resuspension of these NP conjugates provided information on the ability of these derivatives to remain attached to the NP surface as determined by NMR. Spherical NPs were formed for THTQ[n], whereas chains of NPs were observed for diethylene glycol and thioether derivatives. An alternate approach to gold NP synthesis using THTQ[n], in the absence of common reducing agent, NaBH4, was explored with the objective of reducing gold while oxidizing the THT group. Some preliminary investigation on the synthesis of silver NPs using THTQ[n], was also explored with promising results.
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(2022)ThesisParticipatory conservation embraces the idea that nature and people can, and must, work together to manage biodiversity sustainably. Significant live examples—such as that of the Sundarbans mangroves in Bangladesh—suggest that layers of complexity underpin ideas of participatory conservation, often confounding its goals to produce positive outcomes for both nature and people. The Sundarbans of Bangladesh, part of the world’s largest mangrove forest, faces several human-induced challenges, including overharvesting of non-timber forest products and expansion of the commercial shrimp industry. Since 2010, a comprehensive plan has been in place to protect the forest and the 76 communities living there, following the principles of co-management—one of the early participatory approaches in conservation. However, outcomes from the strategies implemented as part of this plan remain unclear. I applied an interdisciplinary mixed-methods ethnographic methodology with an interpretative constructivist perspective to comprehensively evaluate the practised participatory conservation in the Bangladesh Sundarbans. This research is the first to conduct a detailed policy evaluation related to the Bangladesh Sundarbans and its local communities by considering the Kalinchi community as a single case study. Analysis of economic, social, and environmental policies, land use land cover changes, and income analysis are used to examine the appropriateness of practised conservation in this mangrove. This thesis also provides the first-ever detailed qualitative evaluation of participation practised under the co-management arrangements in the Bangladesh Sundarbans, combining the selected community’s lived experiences with the policy administrators’ and practitioners’ perceptions. The empirical evidence from this research suggests that a limited consideration of historical and institutional contexts in conservation planning has restricted the possibility of success. Feelings of negativity and disenchantment expressed by the Kalinchi community indicate that the enabling factors of effective participatory conservation – namely, the highest degrees of engagement and empowerment – were neither enacted nor achieved in the Bangladesh Sundarbans. While the motivations of policy administrators might have been well-intentioned, their assumptions that appeared to have been brought to the processes of participatory conservation saw policy practitioners label the communities living in the Sundarbans as the problem. Tokenistic participation was performed in exchange for the communities’ conservation compliance rather than to facilitate genuine engagement on how they interact with this mangrove ecosystem and what might be altered or initiated to improve the forest and its people’s wellbeing. The research ultimately shows that positive implementation of participatory conservation relies on the motives and practices of decision-makers and their active, nuanced and balanced consideration of the social and political contexts confronting local communities. Until this happens, participatory conservation is doomed to fail in delivering its promises. It is hoped that lessons from this thesis will deliver evidence and provide inspiration for what might be able to be achieved for the next phase of conservation in the Sundarbans and elsewhere.
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(2022)ThesisTropical cyclones have prolonged detrimental effects on the livelihoods and well-being of coastal residents, particularly in developing countries, but no studies have so far assessed cyclone resilience comprehensively, particularly at a local scale. To address this gap, this study assessed resilience to the 2007 Cyclone Sidr (Category 4) in a coastal sub-district in southwest Bangladesh using geo-spatial techniques and residents' responses to an extensive survey; resilience was assessed in each of three phases: before (pre), during (syn) and after (post) the cyclone. The first objective was to assess ecosystem resilience in terms of the services they provided to the community by creating ecosystem service-supply proficiency (ESSP) maps for the three phases. Change-detection techniques determined the amount of cyclone damage to and the subsequent recovery of each ecosystem. The change statistics and residents’ judgments on the ecosystems’ abilities to provide their services were integrated to produce the ESSP maps. The results showed that all ecosystems were impacted by the cyclone to some degree and recovered at different rates. The second objective was to quantify social resilience by examining the different strategies residents employed to plan for, respond to and recover from the cyclone. Resilience indices were constructed with the help of Principal component analysis (PCA) and GIS. Twenty-two important components were identified, among which basic preparedness, emergency response, social bonding, and reconstruction and rehabilitation were found to be the most influential. The exterior unions, even though close to the sea, were more resilient than the less-exposed interior unions. The third objective was to establish a framework for assessing critical-infrastructure (CI) resilience, the ability of CI units to satisfy users’ needs in the three phases. Both GIS based network analysis and household response were used to accomplish this analysis. The results showed that interior unions were resilient than the exterior unions. The overall research outcomes revealed that even in a local scale (~ 286 km2), disaster resilience varies considerably. The techniques developed in this study should be useful in cyclone disaster management, especially in advising legislators and planners on cyclone risk mitigation policies.
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(2021)ThesisThe bubble column evaporator (BCE) is an effective thermal water treatment method based on the mass and heat transfer from the continuously generated heated gas bubbles to the aqueous solution in the BCE column. In this research project, helium has been chosen as the inlet gas to evaporate water from a 0.5 m NaCl solution in a BCE system. The enhanced evaporation efficiency and the reduced enthalpy of vaporization (△Hvap) achieved by helium sparging demonstrated the potential of using helium to improve the evaporation performance of the BCE, while reducing the energy cost. To further increase the working efficiency of the BCE, we added surfactants in the column solution, and the results show that the arrangement of the surfactant molecules on the interface of the bubbles can effectively increase the efficiency of water-vapour transfer into the bubbles. More water molecules can be drawn into the bubbles via the attraction by the hydrophilic heads facing the column solution side, while obstructing their return into the solution by the layer of hydrophobic tails coating the inside of the bubbles. The introduction of surfactants can therefore result in a “molecule diode effect”, apparently improving evaporation efficiency by enhancing the saturation of water molecules within the dry bubbles. The working mechanism of the helium sparge was then studied by contacting helium flow with the salt solution within a membrane contactor. The helium atoms can be sparged into the counter-flowing salt solution through the microscopic pores on the membrane surface. The electrical conductivity of the salt solution, before and after sparging helium flow, was measured and compared; with the increased conductivity demonstrating that helium sparge can effectively enhance the evaporation efficiency, by facilitating the disruption of hydrogen bonds in the water network. This observation corresponds with the experimental outcome that helium flow can result in a higher evaporation performance in the BCE process, compared with other gases at the same inlet temperature. Based on these laboratory results, the research on the BCE process has moved from the laboratory to a pilot plant. A small pilot plant based on the BCE process has been designed and constructed to treat different types of wastewaters, including synthetic seawater, synthetic sewage water and synthetic piggery effluent. The observed amount of evaporated water vapour for the column solutions demonstrated the potential of the BCE process to treat different types of wastewaters on a large scale. In addition, combustion gas was also tested as the inlet gas, for the first time, to treat 0.5 m NaCl solution in the BCE system. The evaporation efficiency increased by 37%, compared with air at the same inlet temperature, most likely due to the existence of water vapour contained in the combustion gas mixture, which increased the transfer of heat to evaporate the surrounding solution. The water quality analysis for the distilled water demonstrated the potential for using the BCE system to produce high-quality water for irrigation or drinking purposes, depending on the type of column solutions.
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(2022)ThesisTiara[n]uril is a new glycoluril-based macrocyclic host with a positively charged cavity made up of glycoluril moieties linked to two pyrazolium groups. As a recently found macrocycle, only a few Tu[n] derivatives have been synthesized and described. Decamethlytiara[3]uril (Me10Tu[3]2+) has received limited attention to date, with some preliminary studies of its chemical and physical properties and a few examples of host-guest interactions have been explored through analytical techniques including NMR, fluorescence, UV-Visible, circular dichroism (CD) and optical rotatory dispersion (ORD). However, the newest derivatives tetrahydrothiophenetiara[n]uril (THT3Tu[3]2+ and THT4Tu[4]2+) are virtually unexplored especially the latter example with a larger cavity. Herein, this thesis aims to reinvestigate the host-guest binding behaviour of Me10Tu[3]2+ with amino acids via fluorescence with a competitive dye (2,6-ANS) in buffer solution (pH 6.8). This study was undertaken to substantiate or discount previously reported molecular associations. The use of a fluorescence probe revealed very weak binding associations in contrast to results previously obtained from binding studies of Me10Tu[3]2+ and amino acids employing CD spectroscopy. Interestingly, this host demonstrated positive binding interactions toward to paramagnetic gases (O2 and nitric oxide (NO)). Similarly, the new derivative THT3Tu[3]2+, illustrated comparable gas binding interaction with O2 and NO, but differed slightly, with the detection of an association with the polar gas CH2F2. However, no binding association was detected for the gases (CH4, CH3Cl, CH3CH2F and N2O) compared to cucurbit[n]uril (Q[n]), which are known to bind these gases. The new THT4Tu[4]2+ derivative with its larger cavity was a prime candidate for the exploration of its potential binding behaviour and properties in the presence of various molecular guests containing different functional groups. As a cationic host (THT4Tu[4]2+), it was anticipated that, binding may favour anionic guests, however, this macrocycle revealed binding affinity toward carboxylic acid rather than carboxylate anions. As an example, at pD 3.0, the THT4Tu[4]2+ showed a positive interaction with L-glutamic and L-2-aminoadipic acids, observed by NMR but these interactions were not observed at pD 6.8. Furthermore, binding interactions were detected for some molecular guests carrying functional groups such as alcohol, ether, dicarboxylic acids and tetrahydrofuran. The positive interactions for both cavity sizes and the different derivatives has added an understanding of the chemical features favourable to host-guest associations with Me10Tu[3]2+, THT3Tu[3]2+ and THT4Tu[4]2+. From the results reported in this thesis it will be possible to build on their supramolecular potential in the future.
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(2022)ThesisWith some recent, notable exceptions, scholarship on slum communities has focused on adverse living conditions, precarity, ill-heath and poverty. Working against this tendency, the thesis argues that the discursive positioning of slums as a failure of urban planning, fails to take slums on their own terms. Defined as the mere negative of planned urban settlement, the slum can only be positioned as a problem requiring a solution. Yet with a change of perspective, slums could themselves be seen as solutions to the diverse problems encountered by a multitude of citizens. Ethnographic fieldwork in Kollyanpur slum, Dhaka, Bangladesh, involving in-depth interviews and case studies into livelihood strategies of its residents, highlights the diverse opportunities that families have within the slum to form non-traditional economic and personal relations. While adversity was a feature of Kollyanpur, the changing power relations within and between households and the forms of social transformation produced by policy intervention were significant forces in their own right. The ‘diverse economy framework’ pioneered by J-K Gibson-Graham and Ethan Miller’s ‘livelihood triad’ are deployed to theorise the opportunities associated with contemporary slum life, including cheap rent, proximity to work, sense of community and the transformed status of men and women within households and the community. While policy intervention into slum existence may produce measurable improvement in quality of life, slum dwellers remain no less vulnerable to eviction and other forms of precarity. Similarly, insofar as slums become part of the vision of urban planning, they are characteristically deemed to be abject sites redeemable only through urban development. From the point of view of planning authorities, then, the value of slums lies in their potential to be developed in settlements that would conform to the clean and sanitized, visually and spatially orderly, modern city ideal. Given the vulnerability that such forms of intervention and governance can produce, precarity is not simply a function of deprivation endemic to the slum but arises from the failure to recognize the role that slums can play in helping the poor to survive. Instead of finding ways to remove slums from cities, efforts to redress the adverse conditions of slums would do well to recognise the achievements of individuals and communities in slums to develop their capacities for health, social wellbeing and empowerment.
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(2022)ThesisSoutheast Asia is among the most tropical cyclone‐prone regions worldwide, and will become more susceptible due to rapid growth in population and economy, and potential changes in tropical cyclone (TC) behaviour due to climate change. A thorough insight into how TCs and physical impacts have been changing in the warming climate in this region is essential to better anticipate, manage and act on TC risks. In this dissertation, first a 50‐Year Southeast Asia TC Landfall Climatology (1970 ‐ 2019) is developed considering the TC attribute disparities among four agency datasets. A shorter period (1998 – 2018) of TC wind and rain impacts is then examined. Finally, landfalling TCs during the last 20 years are simulated using current conditions, and then re‐simulated using future climate scenarios SSP2‐4.5 and SSP3‐7.0, downscaled from the CMIP6 ensemble, by applying the Pseudo Global Warming framework to quantify future changes in Southeast Asia TC exposure. Approximately half of western North Pacific TCs make landfall in Southeast Asia. The Philippines and Taiwan are most vulnerable to TC landfall and associated impacts, followed by southern China, northern Vietnam and Laos. In the worst‐case scenario, TCinduced winds can spread hundreds of kilometres inland, and prior to TC landfall, damaging winds can influence areas quite far inland. TC‐related rainfall occurs across almost the entire Southeast Asia region with more persistent intense rain accumulating near the coast and short‐term intense rain occurring in high‐terrain areas far inland. By the end of the 21st century under the SSP3‐7.0 scenario, landfalling TCs are projected to be 8% more intense at landfall, 2.8% faster and have smaller wind and rain fields. However, the mean rainfall within 500 km of the TC centre increases significantly with amplified increases closer to the TC centre. The historical northward shift in TC landfall will continue into the future with extended tracks further inland. TC exposure and related impacts, therefore, significantly increase in the northern Philippines, Taiwan, southern China west of 117 °E, and north Vietnam, spreading toward Laos, and Thailand, and decrease in the southern areas of Southeast Asia and southern China east of 117 °E.
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(2023)ThesisGlobally, the water industry has to deal with contamination from both manmade and natural sources; for the provision of safe water resources. The Bubble Column Evaporator (BCE) offers a simple method for mass and thermal energy transfer and also has a variety of applications, specifically in water treatment. This work focuses on the development of novel applications of the BCE in: Controlled aqueous precipitation: Strontium sulfate scale deposits have long plagued oil and gas production. Mixtures of strontium nitrate and sodium sulfate in the BCE system were used to precipitate at different degrees of supersaturation. Production of nanoparticles is of interest to many industries and can be obtained by precipitation, electrolysis and so on. The precipitation of several amino acids at their solubility limits and isoelectric points was also studied. The effectiveness of the BCE system was compared to a standard stirring system. The results from solutions of SrSO4 and amino acids show that the BCE system has a significant inhibition effect, hence it can be used as a novel method to control precipitation growth rate and to produce fine particles. Mechanism of bubble coalescence inhibition: No theory has been able to explain the range of interactions involved in bubble coalescence inhibition observed for bubble surfaces in different electrolyte solutions, and many mechanisms almost certainly depend on the particular situation. All theoretical attempts to explain the phenomenon have failed. Many salts reduce the size of bubbles and inhibit bubble coalescence, but some do not. The present work extends the effect to a wider range of solutes. Amino acids were found to inhibit bubble coalescence and reduce the size of bubbles. The effect is the same as that for some inorganic salts but for some amino acids, it is significantly more efficient. Removing water contaminants using adsorbents nucleated in the BCE: Current techniques that are frequently used for the removal of heavy-metal ions were discussed and the use of environmentally acceptable surfactants, based on amino acids (N-octanoyl-cys and N-octanoyl-tyr), were proposed. The adsorbents efficiency such as calcium fluoride, aluminium fluoride and calcium ferric layered double hydroxide were measured based on their particle growth in the BCE and their PFAS removal rates using solid phase extraction (SPE) and liquid chromatography/mass spectrometry (USEPA 537). Further research is required to develop biodegradable surfactants or additives which can replace commercial surfactants, often used in commercial ion and froth flotation processes.
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(2023)ThesisThe global food system faces significant challenges in terms of achieving food and nutrition security, and sustainability. There continue to be many social, economic, and environmental externalities and violations (such as land degradation, water pollution, smallholder livelihood challenges, health and safety threats from the overuse of pesticides, food fraud and food safety challenges, among others) that increasingly challenge the current global food system. How food systems are governed is important in reversing current adverse trends and in achieving long term sustainability. The role of private non-state1 modes of governance as drivers of change in the structure and function of food systems is also widely recognized. While the phenomenon of private governance of food systems is widely studied in the Global North, little is known and understood about the phenomenon in certain regions of the Global South, particularly in Sub-Sahara Africa. The aim of this thesis is to critically examine the role of non-state governance actors in food system change, and especially how they contribute to achieving food systems sustainability in Global South contexts. The thesis deploys a qualitative case study approach to deepen understandings of emerging non-state modes of food systems governance in the Global South from a city-region perspective, and how such governance arrangements promote or hinder sustainability in its dimensions of governance, social, economic, and environmental outcomes. A non-state food governance arrangement in Ghana that utilizes certification as a governance mechanism is used as a case study, and its sustainability outcomes assessed by using the Food and Agricultural Organization’s (FAO) SAFA (Sustainability Assessment of Food and Agriculture Systems) Framework. The study finds that by involving several food system actors in its governing board, the arrangement has achieved legitimacy as a food governance institution. Furthermore, while the arrangement largely succeeds in promoting economic and social sustainability, significant improvements are needed in its contribution to the governance and environmental dimensions of sustainability. This study contributes to current knowledge and understanding of the role of governance in orchestrating food system change in the context of developing countries. The study generates empirical governance lessons for potential transfer into other geographic regions confronting food system challenges. The study further contributes to the discourse about the shift from ‘government’ to ‘governance’, it highlights the adoption of sustainable [agricultural] practices and supports the formulation of more inclusive food system governance policies in developing countries. Finally, it provides evidence on how the Sustainable Development Goals (SDGs) are being pursued in Global South contexts.