The application of DNA sequencing-based approaches to drinking water microbial ecology has revealed the presence of an abundant and diverse microbiome; therefore, the possibility of harnessing drinking water (DW) microbial communities is an attractive prospect in order to address some of the current and emerging challenges in the sector. Moreover, these multiple challenges suggest that a shift in the DW sector, from a “reactive and sanctioning” paradigm to a “due diligence/proactive” based approach may be the key in identifying potentially adverse events. My research project has focused on the characterization of the microbial ecology of full-scale DW systems using DNA sequencing-based approaches, with the aim of exploring how the obtained insights could be applied into a predictive/proactive microbial management approach. To achieve this aim, I have focused my efforts on sampling multiple full-scale DW systems in order to elucidate the impacts of: (i) methodological variation and (ii) system properties on DW microbial communities, using a combination of bioinformatics, molecular biology, microbial ecology and multivariate statistical analyses. Regarding methodological variation, I have elucidated the impacts of sample replication, PCR replication, sample volume and sampling flow rate on the structure and membership of DW microbial communities. This was the first time that methodological variation was explored in the DW context, and the first time that multi-level replication has been tested and applied in DW molecular microbial ecology. Moreover, my findings have direct implications for the design of future sampling campaigns. Regarding system properties, I have shown that microbial communities in DW distribution systems (DWDSs) undergo diurnal variation, and therefore are linked to water use patters/hydraulics in the systems. I have also shown that sampling locations in the same distribution system are similar, with OTUs found across sampling locations at different relative abundance and detection frequency levels. An assessment of the impact of source water type and treatment processes showed that disinfection is a key treatment step for community composition and functional potential, and that several genes related to protection against chlorine/oxygen species are overabundant in chlorinated and chloraminated systems. Looking to the future, I believe that the application of a “toolbox” of techniques is key in shifting towards a proactive approach in DW management, that multidisciplinary synergies hold the possibility of changing the way in which DW systems have been studied and managed for over 100 years.

Water, otherwise known as the pool of life, is the very essence of all living things and as such is vital for survival, whether for living beings, social, economic development or for environmental sustainability. However, its continuing existence is severely threatened for future as a result of climate change, carbon footprint, population growth, environmental damage, combined with natural disasters like droughts and floods. The prospect of an alternative solution such as desalination of sea or brackish water to counter the limit on conventional water resources such as groundwater, which cannot meet demand, is therefore very promising, particularly in arid and semi-arid regions where water scarcity and impaired quality prevails. Consequently, desalination technology has now become a burgeoning industry in North Africa or southern Mediterranean countries, such as in Libya. However, evidence suggests that as a result of by-products being discharged directly into the sea, particularly from coastal desalination plants, the physico-chemical parameters of the receiving water are changing and posing a threat to marine ecosystems. As a result of studies conducted on these parameters to analyse the brine emitted from the Zwuarah and the West Tripoli distillation plants (ZWDP & WTRIS) on the Libyan coastline, evidence shows there is a significant positive correlation at both sites between the biological data and physico-chemical parameters (rs=0.673; p=0.002) and (rs=0.637; p=0.003), which is a clear indication of the impact of brine disposal from both plants on the marine environment. For most of coastal desalination plants on the Libyan coastline, the most practical and least expensive brine disposal option is to discharge it into the sea. It is necessary therefore, to effectively manage desalination reject brine in order to ensure more efficient disposal and reuse. Therefore, it is suggested that experimental studies are aimed for dual benefit of on-site generation of sodium hypochlorite through brine electrolysis and to recover minerals and NaCl from the brine using evaporation ponds, while protecting the environment. Following the first experiment, the outcome of brine utilisation showed a significant production of NaOCl using graphite electrodes (MCCA 1.82 gr/m3). At interelectrode spacing 2 cm and 4 cm, the power consumption was higher, with a greater concentration of sodium hypochlorite generation varying between 10-25 kw/m3 (573-2140ppm) and 29-24 kwm-3 (572-2600ppm) than at interelectrode spacing 6cm 17-13 kwm-3 (350-1790ppm). Consequently, the selection of an optimum electrical consumption level is key in establishing the best scenario in terms of economy and efficiency. Subsequent to the second experiment of brine evaporation in the ponds, results showed that the evaporation rate in August was lower than in September (9.06 mmday-1, 14.63 mmday-1) respectively. The results of the SEM/EDS test showed that due to elevated surges of Na+ and Cl-, halite (NaCl) was the main mineral evident during crystallisation of the salt samples. Hence, the two experiments reveal that brine can be recycled productively, while protecting the environment.

Calcium carbonate (CaCO3) fouling is the most commonly observed fouling phenomenon in cooling water applications. Fouling happens when a process uses cooling water supersaturated with mineral salt crystals (i.e. hard water). Precipitation deposits on heat transfer surfaces whenever these inversely-soluble salt crystals, like dissolved calcium ions, are exposed to high temperature. An online-monitoring system for fouling phenomena was studied experimentally using a mixture of sodium bicarbonate and calcium chloride for carbonate fouling salt in de-ionized water. The effects of different parameters such as surface temperature, flow velocity, and concentration on the calcium carbonate scale formation process were experimentally investigated by using the developed monitoring system. The calcium carbonate deposition rates on five different metal surfaces (Stainless steel 316, brass, copper, aluminum and carbon steel) were investigated. The surface was analyzed by analytical microscopy to investigate the morphology of the deposit layer. The results revealed that SS316 yielded the lowest deposition on the surface. Nowadays, hazardous chemical additives are often used to mitigate fouling but chemicals are expensive and pose problems to the environment. Physical water treatment (PWT), a non-chemical method is good alternative for fouling mitigation method. PWT using zinc and tourmaline as catalytic materials is presented in this research work. Fouling tests were conducted for verification of this PWT method. Artificially-hardened water at 300 mgL-1 was utilized as the fluid medium to form fouling deposits. The hard water flow velocities were varied from 0.15 ms-1 to 0.45 ms-1 and the artificially-hardened water temperature was maintained at 25 oC and the experimental time was set to 72 hours for each run. The results revealed that in the PWT-treatment case, the deposition of calcium carbonate particle is lower compared to those in the No-treatment case. Furthermore, mitigation of calcium carbonate fouling by applying EDTA, EDTA-MWCNT and DTPA-MWCNT-based water nanofluids on heat exchanger surfaces were reported. Investigation of additive (benign to the environment) on the fouling rate of deposition was performed. Assessment of the deposition of calcium carbonate on the heat exchanger surfaces with respect to the inhibition of crystal growth was conducted by Scanning Electron Microscope (SEM). The results showed that the formation of calcium carbonate crystals can be retarded significantly by adding MWCNT-DTPA additives as inhibition in the solution. Moreover, investigation was extended by introducing a non-invasive-monitoring of concentrations of calcium hardness in cooling water. Investigation was conducted with a 2.5 GHz microwave cavity resonator. The principle of electric dipole moment theories were used to analyse the sample solution that occurs as a function of calcium ion content. The sample was centrally positioned in the electric field of the TM010 mode of a resonant cylindrical cavity. COMSOL simulation package was used to compare and validate the experimental cavity resonator frequency. Transmission signal (S21) measurements via Vector Network Analyser (VNA) with different concentrations were investigated and observed linear relationship in amplitude with frequency changes. These research successfully introduce a novel technique of monitoring of water hardness concentration by using non-invasive microwave sensor.

A new model for the simulation of street canyon atmospheric chemical processing has been developed, by integrating an existing Large-Eddy Simulation (LES) dynamical model of canyon atmospheric motion with a detailed chemical reaction mechanism, the Reduced Chemical Scheme (RCS), comprising 51 chemical species and 136 reactions, based upon a subset of the Master Chemical Mechanism (MCM). The combined LES-RCS model is used to investigate both the effects of mixing and chemical processing upon air quality within an idealised street canyon. The effect of the combination of dynamical (segregation) and chemical effects is determined by comparing the outputs of the full LES-RCS canyon model with those obtained when representing the canyon as a zero-dimensional box model (i.e. assuming mixing is complete and instantaneous). The LES-RCS approach predicts lower (canyon-averaged) levels of NOX, OH and HO2, but higher levels of O3, compared with the box model run under identical chemical and emission conditions. Chemical processing of emissions within the canyon leads to a significant increase in the Ox flux from the canyon into the overlying boundary layer, relative to primary emissions, for the idealised case and a number of pollution scenarios considered. These results demonstrate that within-canyon atmospheric chemical processing can substantially alter the concentrations of pollutants injected into the urban canopy layer, compared with the raw emission rates within the street canyon and that such variations have a considerable effect on average within canyon concentrations and the flux of pollutants out of the canyon into the urban background environment.

Research has been undertaken to develop new yttria slurry systems for use in mould face coats for investment casting TiAl alloy, solving the pre-gelation problems of commercial yttria slurry systems to increase slurry life. Meanwhile, the new face coats should also have excellent sintering properties, chemical inertness, surface finish and be easy to prepare. The processes of developing the new slurry started with the filler powder investigation by adding different sintering additives into the yttria powder to achieve good sintering properties. Then the best filler powder candidates were selected to make the slurry. Finally, the new face coat slurries were used to make the shell face coat and the chemical inertness of those shells were investigated through the sessile drop and investment casting. In the research, the filler powder and face coat sintering properties were quantified through density, dilatometer testing, X-ray diffraction (XRD) and microstructural change at different testing temperatures. The interaction of different face coat systems and the metal were identified using hardness tests, sessile drop contact angle and the microstructural change at the metal/shell interface. In this research, three water-based binder face coat systems containing YF\(_3\), Y\(_2\)O\(_3\)+0.5wt% Al\(_2\)O\(_3\)+ 0.5 wt% ZrO\(_2\) (YAZ), and B\(_2\)O\(_3\) additives were found to have similar or even better sintering properties compared to a commercial face coat. Meanwhile, they had long life.

Developing countries pay a high price for water treatment due to importation of water treatment chemicals. Today, more than 663 million people lack access to a clean water supply which results in many deaths. Hibiscus plant seeds, namely Okra, Sabdariffa and Kenaf were investigated to identify their suitability as alternative water treatment materials to provide clean water supply to people in developing countries. Coagulation and disinfection ability of the extracts were assessed using a jar tester and Collilert-18 Quanti-Tray methods whereas dissolved organic carbon (DOC) test was performed using Shimadzu TOC analyser. The results of this work revealed that all the seed samples possess an anionic coagulant protein with a low molecular weight of 39 kDa. The potential of the seeds in crude form was clearly demonstrated, albeit with some issues regarding organic nutrient addition to the clarified water. However, this challenge was overcome by purifying the seed proteins in an ion exchange column where the impact of DOC addition was significantly reduced in the treated water, as demonstrated via fluorescence excitation-emission matrices. Additionally, the coagulant proteins identified in the region of tryptophan-like fluorescence were found to be stable after heat treatment. Furthermore, sludge production using seed extracts was found to be 5 times lower than that of aluminium sulphate (AS) and the pH of the treated water remained largely unaffected after treatment. Floc strength tests, undertaken using a laser diffraction instrument Mastersizer 2000, showed that the use of seeds as coagulant aids in combination with AS improved floc properties, leading to faster floc growth and shorter coagulation time.

Manufacturers are under pressure to reformulate products to make healthier foods, without changing desirability or flavour. A better understanding of product breakdown under oral conditions is essential to structure novel products which are healthier without consumers noticing. In-vitro methods were developed to explore product behaviour when subject to a range of phenomena relevant to those in the mouth, with particular emphasis on lubrication behaviour. Polysaccharides common in food products were mainly used as model systems and salt release was studied in some systems. Three in-vitro systems were developed and used in this study. Firstly, a stirred vessel was developed to gather data of salt release from gelatin, gellan and alginate systems, under quiescent conditions. This was a reliable method of tracking diffusion of sodium ions through the gel structures into a surrounding liquid, showing that diffusion was unaffected by the differing structure of the gels. The second system introduced the effect of compression. Only when pressures are sufficient to rupture the gel samples did compressions affect salt release over that observed in the stirred vessel study. Samples released the majority of their contained salt up to nine times faster, as a result of greater surface areas being exposed. Finally, tribology equipment was developed, which explores the thin film, high shear behaviour of materials. An exploration of available equipment, processing parameters and configurations was carried out to determine optimum surfaces, normal forces and speed ranges which could be related to phenomena occurring in the mouth. The lubricating properties of inhomogeneous polysaccharides with different physical properties were studied. The mixing behaviour of the polysaccharide greatly affected the lubrication response; some mixed quickly so lubricated more efficiently and vice versa. Finally, the developed tribology equipment was used to study the ordering process of a series of fluid gel samples, indicating that lubrication tracks the ordering process, with a decrease in lubrication when structure forms. The pattern of this response is a result of polysaccharide and salt content of the materials, with increasing content enhancing the change in lubrication experienced as more rigid gel particles are produced. The work presented in this thesis shows that the use of in-vitro methods can provide repeatable information on structure behaviour under conditions relevant to the mouth. This information could then be used to develop and assess future food products for their expected performance when consumed.

There is a requirement to predict the spatial variation of particle dry deposition following a nuclear accident. The interaction of landscape features, atmospheric flow and particle dry deposition has been investigated with this in mind. Wind tunnel studies have been used with computational fluid dynamics to predict the deposition rate relative to a flat landscape. Good quantitative agreement was seen for this relative deposition rate. Landscape shapes showed significant effects on deposition rate, increasing it by more than two in some cases, over limited areas. The effect of turbulence intensity, in the absence of landscape features, was also studied and a weak relationship to dry deposition was observed. Computational fluid dynamics methods used in wind tunnel comparisons were extended to a wide range of landscape cases. Deposition rates varied spatially around the landscape features. In general, for hills and ridges, deposition was seen to increase on the windward face, decrease on the leeward face and near wake, and increase in the further wake, before returning to the flat case value. The computational results were applied to a real landscape with the use of a customised geographical information system. Good general agreement was seen when compared with a test case.

In the thesis the structural response of steel tubular wind turbine towers with various design configurations is analysed using FEM modelling. First, a structural response simulation model was validated by comparison with the existing experimental data. This was then followed with a mesh density sensitivity analysis to obtain the optimum element size. Based on this outcome, towers of various heights between 50-250m are considered and investigated with three different design options as follows: (i) thick walled tower with internal horizontal stiffening rings, (ii) thick walled tower without stiffening rings and (iii) thin walled tower with stiffening rings. Based on this analysis, weight reduction ratios are examined in relation to the horizontal sway and von Mises stress increase ratios in order to identify a more efficient design approach between reducing the wall thickness and adopting internal stiffeners. All studied design solutions satisfy the strength and serviceability requirements as specified by the design codes of practice.

This thesis introduces a new methodological approach to provide a framework for environmental health and socioeconomic perception that critically assesses the management of treated wastewater (TWW) reuse practice and options. The methodology combines Multi-Criteria decision Making (MCDM) and Rapid Impact Assessment Matrix (RIAM). The approach uses expert opinion to assess TWW reuse options and converts the qualitative subjective evaluation of experts into quantitative objective and numeric output. The methodology includes the use of a Driver Force, Pressure, State, Impact and Response (DPSIR) framework to analyse the current situation in a specific case study (Kuwait). The research identified the best available TWW reuse options for Kuwait and determined the essential environmental health and socioeconomic criteria affected by the practice of selected TWW reuse options. The latter include recreational and agricultural irrigation, firefighting and industrial and ruses, oil depressurization and groundwater recharge. Options where the public had direct contact with TWW, such as showering, cooking and drinking were rejected. Environmental health criteria were found to be the most significant criteria associated with TWW reuse practice and options, but given current heavy subsidies of wastewater treatment, distribution and transportation, the economic burden was also significant. Further research in this area is recommended to enable a reduction of pressures on freshwater resources through TWW reuse practice and this should be included within a wider context of integrated water management (IWM).