New water directives impose strict regulations to reduce the footprint of treatment operations and contaminant levels, which suggest a performance review of water treatment facilities, including disinfection contact tanks. Serpentine contact tank units suggest plug flow to be the optimal hydrodynamic condition at which disinfection performance is maximized. However, previous studies indicate that flow exhibits a residence time distribution (RTD) which can be significantly distorted from what is dictated by plug flow. Over the years, there has been rising concern over the impact of such digressions from optimal hydraulic conditions on microbe inactivation and the regulation of potentially carcinogenic Disinfection By-Products (DBPs). With the growth of computing power and the advancement of computational models, the potential of contact tank water disinfection optimization by means of numerical modelling techniques can be assessed. In this study, Acoustic Doppler Velocity (ADV) and fluorescent tracer dye measurement campaigns are carried out to assess the hydraulic efficiency of a serpentine contact tank physical model and evaluating appropriate indicators. Then, three-dimensional Computational Fluid Dynamics (CFD) models are set up to simulate the hydrodynamic and solute transport processes for a variety of contact tank geometries examining the effects of inlet design, baffling configuration and tank scale. The simulation capability to reproduce the actual conditions is attested through comparisons against available laboratory results. The CFD approach is subsequently refined with appropriately selected kinetic models, describing the processes of disinfectant decay, pathogen inactivation and DBP formation. Results highlight that computational models can become invaluable tools for the simulation of disinfection processes as they can reproduce the conditions encountered experimentally to a satisfactory extent. Moreover, the optimization of hydraulic efficiency, as studied numerically, facilitates more uniform disinfectant contact time which corresponds to greater levels of pathogen inactivation and a more controlled by-product accumulation.

This thesis is concerned with the management of wood waste generated after demolition of a typical 33 year old coke quenching tower from an integrated steelworks. Wood in the coke quenching tower was treated with traditional waterborne preservative, Copper-Chromium-Arsenic (CCA). Due to the growing environmental concern, changes were introduced in the legislation governing the disposal of waste. Hence, the aim of the thesis was to perform a waste management study by investigating CCA treated wood waste and to develop a waste disposal technique. During the characterisation of the wood waste, elemental analysis was performed to confirm CCA concentration remaining in the treated wood waste. Concentration of CCA elements ranged from 300mg/kg to 10,000mg/kg. The concentration reduced with increase in the years of service life of the treated wood. Leaching tests according to British Standards were performed for different durations from 1 hour to 1 month to determine the leaching behaviour exhibited by the wood. Standard and customised sampling procedures were carried out for leaching tests to study and simulate the loss of CCA from the treated wood during a quenching process. These tests provided a leaching pattern that the loss of CCA follows a trend of As > Cu > Cr which was in agreement with the final concentrations of the quenching tower wood, such that chromium was most resistant to leaching and arsenic was most susceptible to leach. Correlations and linear equations were established between the arsenic-chromium and arsenic-copper leach concentrations. Equations were developed to help in predicting the ratio of leach ability of the CCA elements with respect to each other. It was also found that the wood from the tower contained a substantial amount of iron which was further investigated. The growth ring analysis showed that iron was mainly deposited on the wood surface. The prime sources of iron were identified to be kish, an air borne particulate matter found in steelworks environment as well as coke and coke ash. Leaching studies performed to determine the leachability of iron showed that there was a potential for iron to restrict the mobility of CCA elements in soil. A novel three-step chemical extraction method was developed after analysing the sequential analysis performed with different chemical reagents and leaching behaviour of the CCA wood waste. Step one used sodium hydroxide (NaOH) to break down the wood structure by lignin depolymerisation. The use of NaOH provided alkaline conditions and facilitated the process of lignin depolymerisation mainly to release arsenic as water soluble compounds. This was followed by ammonium chloride (NH4Cl) for release of copper, due to the high affinity of ammonium group to form complexes with copper. Hydrogen peroxide (H2O2) was used as a strong oxidising agent and primarily to release the chromium by forming chromium complexes which are readily soluble in water. The effect of the pH, temperature, concentration and order of the reagent to be used were studied. Therefore, CCA wood was subjected to the three-step process, where the order was designed as NaOH followed by NH4Cl and then H2O2 for 1 hour at 100oC with 1 M, 2 M and 2 M concentration respectively. 98 %, 89 % and 96 % for arsenic, chromium and copper respectively was the extraction percentage achieved by the three step process. The three elements were obtained in a water solution and a dry wood residue. The process showed the potential in an alkaline extraction method with high extraction levels in three hours. The process also provided wood residue with possible uses in paper and pulp industry. In order to complete the treatment method the CCA elements present in water solution obtained after the three-step extraction process were required to be precipitated. The CCA elements present in water soluble state were precipitated by using an electrocoagulation process. Various parameters were analysed including type of electrodes, a suitable pH range, current, and concentration of the solution to optimise the whole process. The pH of the solution played a vital role in the precipitation of the elements. The pH value was adjusted to 4 in order to achieve the maximum removal potential. The mild steel electrodes were selected over the aluminium. The iron ions released from the mild steel electrodes formed insoluble complexes with the CCA elements in the solution as compared to the soluble aluminium ions. The final process was optimised to 15 minutes of duration using mild steel electrodes and 0.8 A current at room temperature. The solution used for the electrocoagulation was diluted to the factor of 1:5. The full process precipitated about 99 % of CCA elements from water which was filtered and analysed. Overall, the thesis provided in-depth characterisation of the CCA treated wood waste arising from a steelworks environment. The leaching behaviour and the presence of iron were studied to provide a better understanding for the disposal of such wastes. A chemical extraction method followed by the electrocoagulation for the disposal of CCA treated wood waste provided a foundation for a scaled up treatment method and final disposal of such wastes.

This thesis is concerned with the swirl stabilised combustion of gases with variable composition, primarily those derived from the gasification of carbonaceous material, and secondarily those that occur naturally, such as shale gas. During the course of this research the temporal composition of producer gas, derived from the gasification of biomass, was studied in order to ascertain the effect its variable fuel composition had on its combustion properties. Its variation was highly dependent on gasifier operation, and despite the stoichiometric air-to-fuel ratio and Wobbe Index of the fuel being consistent, high throat temperatures resulted in high hydrogen content and laminar flame speeds. Alterations in flame speed are linked to thermo-acoustic instabilities, flame extinction and damaging flame propagation. Acoustic response under combustion conditions was investigated, to determine how it altered over a flames stability range. Indicators of impending flame flashback and blowoff were found, which could be utilised to prevent such events from occurring in an appropriate control system, without the need for real time gas analysis. Flames with high hydrogen content display a propensity for flashback, especially in high turbulence burners, such as those found in gas turbines, where thermo-acoustics are also a significant problem. Variation in fuel composition, particularly in the proportion on hydrogen, exacerbates these problems. The diffusive injection effects of three gases on reacting flow structures were investigated as a method of improving the stability of pre-mixed flames. Carbon dioxide was found to improve flame stability, whilst reducing emissions during the combustion of syngas mixtures in a development gas turbine combustor. Monitoring acoustic response and diffusive injection are thus suggested as additional stabilisation methods for the combustion of gases with variable composition.

This thesis presents an Exploratory Data Analysis (EDA) performed on the dataset arising from the operation of the Large Scale Gas Injection Test (Lasgit). Lasgit is a field scale experiment located approximately 420m underground at the Äspö Hard Rock Laboratory (HRL) in Sweden. The experiment is designed to study the impact of gas build-up and subsequent migration through the Engineered Barrier System (EBS) of a KBS-3 concept radioactive waste repository. Investigation of the smaller scale, or ‘second order’ features of the dataset are the focus of the EDA, with the study of such features intended to contribute to the understanding of the experiment. In order to investigate Lasgit’s substantial (26 million datum point) dataset, a bespoke computational toolkit, the Non-Uniform Data Analysis Toolkit (NUDAT), designed to expose and quantify difficult to observe phenomena in large, non-uniform datasets has been developed. NUDAT has been designed with capabilities including non-parametric trend detection, frequency domain analysis, and second order event candidate detection. The various analytical modules developed and presented in this thesis were verified against simulated data that possessed prescribed and quantified phenomena, before application to Lasgit’s dataset. The Exploratory Data Analysis of Lasgit’s dataset presented in this thesis reveals and quantifies a number of phenomena, for example: the tendency for spiking to occur within groups of sensor records; estimates for the long term trends; the temperature profile of the experiment with depth and time along with the approximate seasonal variation in stress/pore-water pressure; and, in particular, the identification of second order event candidates as small as 0.1% of the macro-scale behaviours in which they reside. A selection of the second order event candidates have been aggregated together into second order events using the event candidates’ mutual synchronicities. Interpretation of these events suggests the possibility of small scale discrete gas flow pathways forming, possibly via a dilatant flow mechanism. The interpreted events typical behaviours, in addition to the observed spiking tendency, also support the grouping of sensors by sensor type. The developed toolkit, NUDAT, and its subsequent application to Lasgit’s dataset have enabled an investigation into the small scale, or ‘second order’ features of the experiment’s results. The analysis presented in this thesis provides insight into Lasgit’s experimental behaviour, and as such, contributes to the understanding of the experiment.

A self-healing cementitious material could provide a step change in the design of concrete structures. There is a need to understand better the healing processes, to predict accurately experimental behaviour and to determine the impact on mechanical properties. Micromechanical modelling, with a two-phase Eshelby inclusion solution, is chosen as a suitable framework within which to explore self-healing. The impact of micro-cracking and other time-dependent phenomena are considered alongside self-healing experiments and the numerical mechanical strength response. A new approach describes simulating inelastic behaviour in the matrix component of a two-phase composite material. Quasi-isotropic distributed micro-cracking, accompanying volumetric matrix changes, is combined with anisotropic microcracking arising from directional loading. Non-dilute inclusions are homogenised and an exterior point Eshelby solution is used to obtain stress concentrations adjacent to inclusions. The accuracy of these solutions is assessed using a series of three dimensional finite element analyses and a set of stress/strain paths illustrate the model’s characteristics. The problem of autogenous shrinkage in a cementitious composite is applied using a volumetric solidification and hydration model, which quantifies the effects of micro-cracking. Experiments on early age concrete and mortar beams showed that autogenous healing is primarily due to continued hydration. A novel self-healing model focuses on mechanical strength recovery of micro-cracked material and considers healing whilst under strain as well as allowing for re-cracking the healed material. The constitutive model is combined with a layered beam model to allow successful comparisons with experimental results.

In this thesis, the focus is on addressing the gaps that exist between (a) utility companies’ efforts to implement and diffuse Internet-based services and (b) their goal to achieve users’ expectations in terms of managing their domestic utility services online. The research highlights the importance of shifting the focus towards a user-centric and integrated virtual enterprise service delivery platform that factors in user demands and functions as a medium for interaction between all utility parties to cooperate in achieving efficient resources usage, while promoting sustainability and environmental welfare. The research involves a critical investigation of users’ perspectives related to the success of the creation of the proposed platform in the utility domains, with particular emphasis on its potential influence on user perceptions in terms of benefits, technology-fit, acceptance, and service adoption; in addition to the potential role of such platform in promoting individual pro-environmental sustainability. The research methodology design involves the collection of information (n=1142) about individual opinions, views, beliefs and expectations towards the new conceptualised innovation platform. The methodology involves four main stages. The initial stage was devoted to defining the research problem, conceptual model, developing a theoretical validation framework and the research questions with a formulation of the related hypothesis. This stage of the research design is critical to identify the key underpinning aspects of the research topic and to determine the main variables that have an impact on the research problem. The second stage involves an empirical investigation of Internet-user’s perceptions of task-technology fit, new technology innovation adoption, barriers, trends and difficulties for both existing and future technology innovation as well as an electronic service delivery approach, using a quantitative questionnaire survey. In the third stage, a mock-up prototype system is implemented to illustrate and validate the proposed research concepts. The last stage, aimed at analytically validate users’ perspective towards the new technology innovation platform as formulated in the research model and to predict their willingness to adopt the platform and impact on their individual sustainable behaviour. The resulting validated model and service platform provide a means for utility companies to deliver user accepted electronic utility management services, while promoting environmental friendly behaviour.

This thesis presents details of a numerical programme of study on the themo-hygrochemical (THC) processes occurring during the self-healing of cementitious materials. A comprehensive THC model, which is mechanistic in nature, is proposed and implemented in the framework of the finite element method. The aim of this model is to develop a useful computational tool that is capable of realistically predicting damage recovery in terms of the crack filling observed under specific environmental conditions. The early age and long term behaviour of the cementitious materials is simulated by solving a boundary value problem which couples moisture-temperature-ion transport mechanisms by means of mass and enthalpy balance equations. The model assumes that all the transport processes occur at the capillary pore level and that the selfhealing is driven by ongoing hydration. In this context, attention is focused on developing an innovative microstructural model that can predict the quantitative evolution of the capillary porosity. The microstructural model is based on an existing colloidal classification of the water forms present in the clinker hydrates, on hydration kinetics principles and on the stoichiometry of the Portland cement. The effect of the aggregate absorption on the capillary porosity is also examined. Firstly, the adopted theoretical considerations regarding the transport of moisture and temperature in cement-based materials are validated by comparing the numerical findings of the TH component with the reported results of three different sets of drying experiments. Then the THC model is applied to the simulation of a crack recovery experiment undertaken at Cardiff University. In both cases the proposed model was found to capture the essential characteristics of the thermo-hygro-chemical behaviour of cementitious materials.

The present thesis addresses shape sensitivity analysis and optimization in linear elasticity with the isogeometric boundary element method (IGABEM), where the basis functions used for constructing geometric models in computer-aided design (CAD) are also employed to discretize the boundary integral equation (BIE) for structural analysis, and to discretize the material differentiation form of the BIE for shape sensitivity analysis. To guarantee water-tight and locally-refined geometries, we use non-uniform rational B-splines (NURBS) and T-splines for two-dimensional and three dimensional problems, respectively. In addition, we take advantage of the regularized form of BIE instead of the singular form, to bypass the difficulties caused by the evaluation of strongly singular integrals and jump terms. The main advantages of the present work arise from the ability of the IGABEM to seamlessly integrate CAD and numerical analysis, since they share the same boundary representation of geometric models. Therefore, throughout the whole shape optimization, it does not need a costly meshing/remeshing procedure. Moreover, the control points can be naturally chosen as the design variables, and the optimal solution can be directly returned to the CAD system without any smoothing procedure.

Our built environment is responsible for some of the most serious global and local en- vironmental change. The construction industry therefore faces pressure to increase the sustainability of its practices re ected in the development of stringent regulations and sustainability assessment methods, designed to mitigate such negative impacts. How- ever, the well-established methods (e.g. BREEAM, LEED, SBTool, and CASBEE) have not originally been designed to suit developing countries (including Saudi Arabia). This study therefore proposes to customize an adapted Saudi Environmental Assessment Method (SEAM). This study to begin with investigates the most important and globally widespread environmental assessment methods: BREEAM, LEED, SBTool, and CAS- BEE. It identifes areas of convergence and distinction in order to enable the consolida- tion of environmental criteria into new potential schemes. As sustainable and ecological context are usually regarded as multi-dimensional, scientific evidence proposes that a technique based on consensus is most appropriate for the establishment of inclusive and efficient building environmental assessment schemes. Therefore, a consensus based ap- proach is used to deliver: (a) applicable assessment categories and criteria for the Saudi Arabia context and (b) its weighting system. Hence, the Delphi technique and Ana- lytic Hierarchy Process (AHP) are selected and conducted in four successive systematic consultation rounds, involving world leading experts in the domain of environmental and sustainable assessment schemes, as well as professionals and highly-informed local experts from academia, government and industry. These two stages resulted in the development of SEAM criteria and its weighting system.

This thesis describes a study of reactive transport processes in fractured rock in response to high pressure gas injection and displacement. This is achieved through the development and application of a theoretical and numerical modelling platform. A dual porosity, dual permeability framework has been formulated based on a mechanistic approach, which considers the coupled hydraulic, gas/chemical and deformation behaviour of fractured rock. The fracture network and porous rock matrix were treated as overlapping continua with distinct transport and storage properties. Flow in each continuum was considered by advection, diffusion and dispersion mechanisms, and a sink/source term was included for the kinetically controlled sorption of multicomponent gas. A mass exchange term was introduced to couple the continua and allow pressure and concentration differences to develop. The transport properties of non-ideal gas mixtures at high pressure were characterised by appropriate constitutive relationships. The developed model has been incorporated in an existing coupled thermal, hydraulic, chemical and mechanical framework. A numerical solution was obtained using the finite element method for spatial discretisation and the finite difference method for temporal discretisation. Verification of the approach proposed has been addressed via a series of benchmark tests. The results obtained provide confidence in the accuracy of the numerical implementation of the dual porosity governing equations, including a time splitting approach used to couple the transport module with the mass exchange and geochemical reaction modules. Key theoretical features have been included to enhance the model capabilities and enable application of the model to study species dependent coal-gas behaviour, especially in relation to carbon dioxide sequestration in coal and enhanced coal bed methane displacement. The development of constitutive relationships describing the feedback of dual porosity physico- and chemo-mechanical deformation on gas transport in coal was considered in detail. Furthermore, a combination of two first-order rate models was used to include the specific gas sorption behaviour in coal. A detailed validation of the model using high resolution experimental data on gas interactions, transport and displacement in coal has been included. The theoretical models developed for coal-gas interactions were first evaluated, providing a platform to facilitate numerical simulations of gas injection and displacement experiments, performed on intact samples of anthracite coal from the South Wales coalfield. Under the conditions considered and for two injection scenarios, namely, nitrogen and subcritical carbon dioxide injection, it was demonstrated that the model is capable of simulating the salient physical and chemical phenomena involved in gas transport and methane displacement in coal. More advanced simulations have been performed to study the behaviour for a larger sample size and different gas injection pressures and compositions. The injection of supercritical carbon dioxide and two carbon dioxide-rich gas mixtures at high pressure was considered. It is claimed that a substantive insight has been gained into the coupled behaviour of the material at the laboratory scale. Overall, the analysis carried out in this research indicated that species dependent chemo-mechanical deformation was the dominant factor in smaller core samples. Fracture-matrix exchange and preferential methane desorption by carbon dioxide only became more apparent in larger samples. An appreciation of the effects of sample size on the behaviour observed is therefore important when interpreting experimental data, and implies that due care must be taken in interpreting laboratory scale results towards larger scale applications. In this work, the capabilities of the new model have been showcased with regards to the study of coal-gas systems. Importantly, the developments presented are more generally relevant and thus enable the study of a broad new range of applications involving multiphase, multicomponent gas/chemical transport in fractured rock.