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Soil erosion is a global problem, affecting much of the world’s agricultural land. As the world’s population increases, the pressures placed upon the land resource to provide space for food production, leisure, housing and industrial facilities also increases. Thus it is vital that the land resource is as productive as possible. As soil erosion is the major cause of soil degradation globally, it is vital that methods for accurately monitoring the degree of erosion from a site, and the effectiveness of any remediation attempts are available. Reported here is the development of a novel soil erosion particle tracer, based upon a lanthanide chelate complex doped silica particle. The luminescent lanthanide chelate complexes were comprised of 2-thenoyltrifluoroacetone (TTA) and 2-pyridinol-1-oxide (2PO) coordinated with either trivalent europium or terbium ions. These complexes were then doped into silica sol-gel particles using a core shell technique. This method resulted in the synthesis of two luminescent soil tracers, targeted to two of the key eroded soil fractions; fine silt (63-250 μm) and clay (< 1.2 μm). The behaviour of the tracers was analysed within three different soils obtained from the Glensaugh research station. They retained their luminescence when mixed with soil, and could be detected at concentrations of 10 mg tracer / kg soil using a standard benchtop fluorescence spectrometer (Perkin Elmer LS55B). Scanning electron micrographs indicated that the tracer particles interacted with the soil particles, whilst soil sedimentation experiments demonstrated that the tracer particles had a similar sedimentation pattern to natural soil particles. Soil microbial respiration studies were performed for the tracers and showed that the tracers did not significantly impact the soil microbial population. Studies of the luminescence stability of the tracer in soil over time showed that the tracer could be detected in the soil for one season (approximately 3 months). A prototype rainfall simulator, designed to simulate the kinetic energy of raindrops on the surface of the soil, was developed, and used during a series of rainfall simulation experiments. These simulations were performed at two different rainfall intensities (30 and 90 mm.h-1) and both of these conditions resulted in movement of the tracer particles within the plot. This movement was both horizontal, in overland flow over the plot surface, and vertical, through the plot. The pattern of tracer movement reflected that of the soil mass moved, and as such indicated that the tracers exhibited similar transport behaviour during the erosion simulations performed. These initial simulations demonstrated that the tracers can be detected at low concentrations within the soil using standard laboratory equipment, and that they move with the eroded soil particles during simulated soil erosion experiments. As such, these tracers are excellent candidates for further study in larger scale erosion events.

Spent oil based drilling fluid and cutting wastes are global liabilities due to their hazardous hydrocarbon content which impacts negatively on flora, fauna, and global carbon footprint. The formulation of two demulsifiers to ensure chemically enhanced phase separation of this waste into oil, water and solid components was successfully carried out in addition to recycling the solid phase into PA6 nanocomposite materials. Initial characterisation of the untreated waste was carried out by Fourier Transform Infra Red (FTIR) for total petroleum hydrocarbon (TPH) analysis, Inductively coupled plasma optical emission spectrometry (ICPOES) for quantitative elemental analysis and Energy dispersive xray analysis (EDXA) for qualitative elemental composition amongst other characterisation methods. The analysis showed that the sample had a high hydrocarbon load of 662,500mg/kg and a high heavy metal load for Pb of 122mg/kg. No As, Cd, Hg were detected. The demulsifier formulations were composed of isopropanol, sodium dodecyl sulphate, poloxamer, sodium chloride, chitosan in 0.2M acetic acid and deionised water for demulsifier S4 and addition of phosphoric acid for demulsifier S3. Hydrocarbon reduction on the extracted solid phase nanofiller S3 and nanofiller S4 was 98.6% and 98.5% respectively after demulsification. The demulsified spent oil based drilling fluid solid extracts were below OSPAR regulation of < 1% oil on cutting by weight. However, recycling of the recovered solid was carried out in order to achieve environmentally sustainable management of the waste in Polyamide 6 (PA6) nanocomposite manufacture/fabrication. The formulation of different blends of PA6 nanocomposite materials from untreated, demulsifier treated and thermally treated drilling fluid and cuttings was successfully achieved. Nanocomposite leaching test showed Pb immobilisation. The flexural and compressive - modulus and strength of the PA6 were markedly improved in the presence of the nanofillers and glass fibre. This was attributed to the reinforcement, exfoliating, stiffening, rigidity effect of the nanofillers. S6 (untreated drilling fluid) nanofillers significantly improved the mechanical properties of PA6. This was attributed to the increased interfacial bonding between the fillers and the polymer matrix as a result of the petroleum hydrocarbon present in the sample. The Thermogravemetric analysis (TGA) results showed that nanocomposites PA6/S3 and PA6/S3/GF30 had improved the thermal stability of PA6 by 13.6% and 38.8% respectively compared to PA6/S2 and PA6/S2/GF30 (simulated commercial nanocomposite materials) that improved PA6 by 9.7% and 35.8% respectively.

Passive sampling, as opposed to the conventional spot or bottle water sampling technique, has shown to be reliable and efficient in monitoring the toxicologically relevant, freely dissolved (e.g. bioavaialable) concentrations of a wide range of organic contaminants in water. At the same time, partitioning controlled delivery (passive dosing; PD) techniques promise to overcome many of the challenges associated with toxicity testing of hydrophobic substances that may bias the interpretation of toxicity data. The present study investigated the feasibility of coupling silicone rubber passive sampling devices (SR-PSDs) with bioassay techniques for both chemical and ecotoxicological assessment of complex mixtures of organic contaminants in the aquatic environment. SR-PSDs were deployed in water at various locations within the Ythan catchment (north east, Scotland, UK), Forth estuary and the Firth of Forth (east coast of central Scotland, UK) for 7 to 9 weeks. Following retrieval, extracts from the SR-PSDs were analysed for dissolved concentrations of a variety of organic contaminants including PAHs and PCBs using GC-MS and GC-ECD respectively and were screened for a wide range of pesticides using GC-MS/MS and LC-MS/MS. The extracts were further evaluated for acute cytotoxicity (i.e. neutral red uptake assay) and EROD induction potential using rainbow trout liver cell line (Oncorhynchus mykiss; RTL-W1) and for phytotoxicity and developmental toxicity potential using algal growth inhibition test (with a marine phytoplankton, Diacronema lutheri) and fish embryo toxicity test (with embryos from zebrafish Danio rerio) respectively. Overall, the individual and total dissolved concentrations of PAHs (ΣPAH40; parent and branched) and PCBs (ΣPCB32; ortho and mono-ortho) measured in water from the Ythan, Forth estuary and Firth of Forth were relatively low compared with other studies using PSDs. A number and level of pesticides, including insecticides, herbicides and fungicides of varying hydrophobicity (log KOWs ~2.25 to ~5.31) were detected in the silicone rubber (SR) extracts from the Ythan catchment, the Forth estuary and the Firth of Forth, suggesting input mainly from agricultural run-off and possibly from direct discharges. No statistically significant (p<0.05) acute cytotoxicity was observed following 48 h exposure of RTL-W1 cells to SR extracts from the Ythan catchment. But, on a sublethal level, for every site, statistically significant EROD activity was observed to some degree following 72 h exposure. In addition, developmental and algal toxicities on embryos of D. rerio and D. lutheri respectively, were measured in all the deployed samples compared with the procedural controls (undeployed samples). Interestingly, extracts of SR-PSDs from the Forth estuary and the Firth of Forth exhibited growth inhibitions on D. lutheri that were similar to those of extracts from the Ythan, even though, fewer numbers of pesticides were detected in the Forth estuary and Firth of Forth than the Ythan. This suggests that pesticides were not solely responsible for the observed effects in the Ythan catchment. To further improve data from toxicity testing of hydrophobic substances, the study identified the use of SR O-rings as a suitable passive dosing format in in vitro toxicity tests and was partially validated through their use in dosing RTL-W1 cells with two individual PAHs and subsequently determining cytotoxicity and EROD-activity.

This PhD thesis investigated solid and liquid waste treatment systems for Sureclean, a waste Management company based in the North of Scotland. Sureclean receives a diverse range of waste streams and the increasing need for sustainable development as well as stringent environmental legislation motivated this research to develop an integrated waste treatment system. Waste characterisation was conducted using a range of analytical instrumentation to identify the TPH, COD, heavy metals content, TOC, and particle size of Sureclean waste streams. From there, four treatment systems were investigated utilising Sureclean waste streams: mechanical separation, chemical treatment, electro-coagulation and the advanced oxidation process. Laboratory and field trials were conducted using these different treatment techniques and the analysis was performed to verify the treatment results. The result of these trials led to the development of four modular waste treatment units, that form the outcome of this research: the Sureclean Water Treatment System (SWTS), a filtration based mechanical separation system was shown to reduce the TSS, BOD and TOC content of an oily wastewater; the Sureclean Sludge Separation System (SSSTS), a chemical-enhanced filtration based system was demonstrated to reduce 52.6 % of the sewage sludge volume; the Sureclean Electro-coagulation Water Treatment System (SEWTS), a system that agglomerates colloid particles and demulsifies oil removed 99.9 % of TPH from Sureclean interceptor effluent; and the Sureclean Advanced Water Treatment System (SAWTS), an advanced oxidation process which was demonstrated to reduce the TPH of a contaminated groundwater collected from an ex-gas work. The treated effluent could be discharged to Sureclean interceptor. The four treatment units developed in this research expanded Sureclean waste treatment capabilities and an integrated system was developed to treat different waste streams and to improve the treatment efficiency thus increasing the revenue and future waste stream options for Sureclean.

Modern technological advancements in our lifestyle have caused a significant increase in the consumption of energy. With this growing demand, people are more concerned about the rational use of existing limited energy and searching for alternative forms of environmentally friendly energy sources to reduce polluting emissions. Proton Exchange Membrane (PEM) fuel cell has shown and demonstrated that potential to be a suitable alternative power source because of its simplicity of design, load following capabilities, efficiency, feasibility and quick start-up. Although having these splendid advantages, cost and durability of PEM fuel cells are one of the major challenges that needed to be overcome. Three-dimensional single-phase and multi-phase isothermal PEM fuel cell models have been developed to investigate the transport limitations of fresh reactants and its effect on cell performance. The governing equations (continuity, momentum and species transport) with appropriate source terms were solved using computational fluid dynamics (CFD) technique. A user defined function (UDF) code was developed considering source terms for porous zones, effective diffusivity models for species transport inside cells and electrochemical reactions at catalyst layers to predict cell voltage at an average current density. The average current density and net water transfer coefficient, used to calculate the source terms, were calculated using auxiliary equations and linked to the solver through UDFs. Parametric studies were performed to determine the optimal operating conditions and geometrical design of PEM fuel cell. The simulation results show that gas diffusion layer permeability has no effect on cell performance for a value lower than 10-11 m2. GDL porosity is one of the major design parameters which have significant influence on limiting current density, hence on cell performance. Land area width of PEM fuel cell shows influence on cell performance. Low membrane thickness provides higher cell performance and approximately 50% reduction in membrane thickness results approximately 100% improvement in cell performance at high current density of 1.0 Acm-2. Bruggeman correlation was used in most of previous modelling work for explaining the diffusion of species though porous GDL and CL, but this thesis considered other types of effective diffusion models and investigated the effect of diffusion models on cell performance at high current densities. Tomadakis and Sotirchos (1993) anisotropic model produces cell voltage much closer to the experimental values. Therefore, anisotropic diffusion model should be utilized in PEM fuel cell modelling to minimize modelling uncertainties. A two-phase flow, steady-state, three-dimensional PEM fuel cell model considering the phase change effect of water has been developed in the final phase of the thesis. Flooding inside the cell was captured at high current density using the model for a condensation value of 10.0 s-1. Finally, parametric studies were performed based on isotropic and anisotropic GDL permeability cases. Modelling results suggest that isotropic permeability cases have strong influence on cell performance compared to anisotropic cases at high current density.

For the tidal current power industry to progress, simple models for predicting the performance of tidal current turbines are needed. Currently the aerodynamic models developed for wind turbines are typically used to predict tidal turbine performance. There are a number of significant differences between wind and tidal turbines so these models will not provide a good representation of tidal turbine performance. The main aim of this project was to show the magnitude of the differences between wind and tidal turbine performance caused by dissimilarities in wind and tidal turbine operation. Two main areas were investigated: the effects of energy extraction on flow speeds and the effect of the proximity of the boundaries. An analytical model was developed which allowed the effect of the number of turbines at a site on the performance of each turbine to be investigated. The magnitude of the change in performance was found to depend on the design and geometry of the turbines and the drag coefficient of the site. The model results indicated that, typically, there will be no noticeable reduction in the power generated by single or small farms of turbines, but installing large farms of turbines will cause significant reduction in the power generated per turbine. An analytical model was developed which allowed the effects of blockage on performance to be investigated. Applying the model to a single turbine in the Sound of Islay indicated that the performance of a realistically sized turbine in an actual tidal channel will differ from that predicted by an aerodynamic model. The effect of the proximity of the turbine to channel boundaries was investigated and performance was found to decrease as the free surface was approached. In all of the areas investigated the performance tidal turbines has been found to differ significantly from the performance predicted by aerodynamic models. This implies that it is not appropriate to use aerodynamic models to predict tidal turbine performance.

Climate change and energy security are key issues motivating the development of Tidal Current Energy (TCE) technology. Small scale model testing of TCE devices is a major challenge facing the technology due to turbulent flow in tidal currents environment and scaling is a fundamental engineering procedure for prototype development and optimisation for cost effectiveness. This thesis presents the outcome from investigating Dimensional Scale Effects (DSE) and Turbulence Scale Effects (TSE) of a monopile support structure using Computational Fluid Dynamics (CFD). Scale models dimensioned according to the Froude scaling criterion was used for the DSE investigation whereas real time turbulent velocity profile sampled from the Firth of Forth, Scotland was used for the TSE investigation. The real time turbulent velocity profile is influenced by waves, channel sidewalls, seabed roughness and other natural, physical and biological processes occurring in the estuary. The following observations were made: 1) For the DSE, the drag coefficient of scale models within the subcritical flow regime varies as a function of a non-dimensional length and velocity scale. Equations for estimating the scale effects are presented. 2) The TSE investigation demonstrates a novel application of Acoustic Doppler Current Profiler (ADCP) data from a real site to generate significant upstream turbulence structures suitable for testing tidal current energy devices. The results show that, significant increase in turbulence in terms of maximum vorticity magnitude, by a factor more than 4, can be achieved in an empty channel and seabed drag coefficient is significantly reduced when compared with simulations done by specifying theoretical velocity profiles in a Large Eddy Simulation (LES). 3) Ambient turbulent flow around a monopile support structure causes a significant reduction in drag coefficient compared with simulations done by specifying the uniform and the 1/7th power law velocity profiles. The simulation results further demonstrate the possibility of representing a large scale prototype with a small scale numerical simulation domain that captures ambient vortex structures in real sites and that, the use of uniform flow and 1/7th power law velocity profiles in numerical simulations would lead to overestimation of hydrodynamic forces acting on an energy device and underestimation of available energy for extraction due to lower seabed drag coefficient. Further work is recommended to investigate effect of ambient turbulent structures on hydrodynamic loading and performance of a turbine undergoing sea trials using the methodology proposed in this study. The methodology has potential application to oil and gas subsea structures.

Novel glass tracers, organic and inorganic polymers based on narrow band atomic fluorescence, have been developed for deployment as environmental tracers. The use of discrete fluorescent species in an environmentally stable host has been investigated to replace existing toxic, broad band molecular dye tracers. The narrow band emission signals offer the potential for the tracing of a large numbers of signals in the same environment; this has been investigated by examining multiple doped tracers which have the potential for coding to specific effluent sources or particulates. The concept of using lanthanide doped glasses as environmental tracers has been demonstrated. The spectral characterisation and concentration studies of the lanthanide doped tracer allow the selection of parameters to produce future tracers and detection systems for particular applications. Therefore by altering the chosen lanthanide dopant, number of dopants, dopant concentration and using selective excitation and emission wavelengths there are a huge number of possible unique tracer combinations. The significantly narrower bandwidth emission peaks of the lanthanide based tracers achieve more selective detection of multiple tracers without overlap interference and gives the potential to selectively and simultaneously monitor many different tracers in the same location. The spectral lifetime characteristics of the lanthanide tracers are very different from the lifetime of background fluorescence which is typically molecular in origin. This is an extra discrimination against background interference and is an important additional advantage of using lanthanide based tracers. Overall this work shows that a very large number of unique environmental tracers can be obtained by varying the concentration, the number of lanthanide ions in a glass and also the possibility of using organic and inorganic lanthanide chelate doped tracers.