The chemistry of aerosol particles is critical to the influence said particles have over human health, air quality and the distribution of nutrients across the world. Current models estimate that windborne dust represents the movement of thousands of teragrams of solid material of varying composition and solubility across continents and into the world’s oceans. Understanding the composition and surface reactivity of anthropogenic particles from industry, agriculture and vehicle emissions is vital to understanding their potential impact on the world, and the structure and behaviour of inhalable pharmaceuticals is a strong determinant of their efficacy. The following work examines a broad selection of natural and anthropogenic particulate samples with synchrotron-based techniques, including analysis of ship emissions collected directly from stacks for the first time. The effect of simulated atmospheric acid processing on the solubility of iron on coal fly ash is evaluated, and optical trapping is used in conjunction with analytical techniques to observe the influence of relative humidity on the properties of pharmaceutical aerosols and aqueous droplets containing fluorescent protein solutions.

This thesis develops a participatory modelling process to study improvement in the management of irrigation efficiency, including physical and social dimensions in the context of arid and semi-arid regions of Iran. This study develops an interdisciplinary and participatory method to understand and strengthen collective decision-making in local Iranian farming systems. Specific attention is given to groundwater irrigated agricultural practices under the Iranian governance system to provide wider context. Kashan City, in central Iran is selected as a case study area for specific reasons, such as historical water use, the farmers’ rich indigenous knowledge, and successful agricultural practices under conditions of water scarcity. The accessibility and willingness of local farmers to engage in a participatory modelling process are considered. The thesis suggests the first use of role-play simulation for irrigation management practices in Iran, is an effective and insightful method of achieving adaptive management solutions. The application of an innovative participatory simulation modelling with farmers revealed their main incentives for collective irrigation practices, their capabilities to learn and evaluate the system. It is argued that management decisions have major impacts on farmers’ livelihoods and therefore it is essential to integrate farmers’ perspectives in local governance to sustain agricultural productivity.

This hypothesis driven research investigated the removal of Cu, Fe, Zn and Mn from synthetic metal solutions and real Acid Mine Drainage (AMD) from Wheal Jane mine in West Cornwall UK, employing waste gas sludge (BOS sludge) which is an end waste reside generated from steel production. Batch experiments showed the efficiency and adsorption rates increased with reduction in BOS sludge particle size, lower in initial metal concentration, increase in BOS sludge dosage, an increase in initial pH and increase in agitation speed. Fitting of the Langmuir isotherm model to experimental data gave a good fit with correlation coefficients R\(^2\)≥0.99 and the selectivity series of BOS sludge was: Cu\(^2\)\(^+\)>Fe\(^3\)\(^+\)>Zn\(^2\)\(^+\)>Mn\(^2\)\(^+\). For single and multiadsorbate systems, a Pseudo second order model was the most appropriate theory to satisfactorily describe experimental data and the rate limiting step for this process was chemisorption. Adsorption was spontaneous and high pH promoted adsorption possibly by precipitation and/or ion exchange processes which had taken place between the exchangeable cations present in BOS and solutions. Results from the treatment of real and synthetic AMD solutions revealed that BOS sludge worked well and hence BOS sludge as a novel low cost material could be used as a sustainable sorbent in AMD treatment technologies.

The first part is concerned with dynamic aggregated modelling of large offshore wind farms and their integration into power systems via VSC-HVDC links. The dynamic aggregated modelling of offshore wind farms including WT-DFIGs and WT-PMSGs are proposed to achieve effective representations of wind farms in terms of computational time and simulation accuracy for transient stability analysis. Modelling and control of VSC-HVDC systems for integration of offshore wind farms are investigated. Comparisons of two control schemes of rectifier-side converter are carried out to evaluate their dynamic performance for integration of these offshore wind farms in terms of transient stability. The second part is to address the advanced transmission systems with innovative HVDC configurations. Feasibility studies of updated schemes of monoplolar CSC-HVDC link with support of monopolar VSC-HVDC link as the hybrid bipolar CSC/I{VDC system is carried out to deal with two key issues of CSC-HVDC. Small-signal modelling of MTDC grids is investigated and parameter optimisation of PI controller of converters in MTDC grids is carried out using PSO method based on small-signal models of the system at multiple operating points to obtain optimised parameters of PI controllers to improve dynamic performance of MTDC grids at multiple operating points.

The work conducted in this thesis examines the potential for emissions of flame retardants (FRs) from a range of treated end-of-life materials during and following disposal. A series of standardised leaching experiments were developed and conducted to study FR leaching from a range of waste flame retarded products, including: textiles, EPS and XPS building insulation foams, cathode-ray tube plastics and polyurethane furniture foams (PUF). The leaching tests were conducted using a range of leaching fluids, with the view of simulating the characteristics of real landfill leachates. A number of different test parameters were examined, such as a variety of dissolved humic matter concentrations, landfill relevant pHs between 5.8 and 8.5, landfill relevant temperatures, the effect of agitation, contact durations and longer term cycles of periodic wetting and draining of waste. It is apparent from these experiments that despite the relatively hydrophobic physicochemical properties of brominated FRs (BFRs), they are able to leach from waste materials at substantial concentrations. Concentrations of ƩPBDEs (polybrominated diphenyl ethers) in the leachate from the leaching experiments in this study ranged from 14,000 – 200,000 ng L-1, while concentrations of ƩHBCDD (hexabromocyclododecane) ranged from 170 ng L-1 – 13,000 ng L-1 in textile leaching experiments and from 13,000 ng L-1 – 4,200,000 ng L-1 in building insulation foam experiments. BFR leaching appears to be a second order process, whereby a period of initially intense dissolution of more labile BFR is followed by a slower stage corresponding to external diffusion of the soluble residue in the material. Tris (chloroisopropyl) phosphate (TCIPP) is more readily soluble in water than the BFRs studied, and leaching of TCIPP from PUF appears to be a first order process. Concentrations of TCIPP in the leachate from the leaching experiments in this study ranged from 13 mg L-1 – 130 mg L-1. In serial batch leaching experiments, >95 % of TCIPP was depleted from the flexible PUF after the sixth batch (168 h total contact). Hence, leaching is potentially a very significant pathway for TCIPP emissions to the environment. A small survey of waste soft furnishings from a variety of UK domestic and office locations was also conducted, to help determine the total FR content entering the UK waste stream as a result of the disposal of soft furnishings. The predominant FR detected was TCIPP. Closed test chamber experiments investigating the effect of temperature on volatilisation of TCIPP from polyurethane foam were conducted. These experiments show volatilisation of TCIPP from PUF to increase exponentially with temperature and to constitute an additional potentially significant pathway for emissions from UK MSW landfills, with TCIPP emissions via volatilisation from landfilled PUF estimated to range between ~200 and ~3,800 tonnes yr-1.

The main aim of this thesis is to verify the suitability of waste animal fat, obtained from animal by-products in a process called rendering, as a fuel for internal combustion engines. This work is an attempt to provide guidance and minimal requirements for animal fat to be utilised as fuel. The properties of tallow were monitored on a weekly basis throughout a period of one year. Some properties, namely acidity, showed significant variability. Possible reasons causing variable and high acidity are given together with a proposal for an acidity removal method. The available laboratory facilities enabled the verification of changes in fat's viscosity, density, surface tension and lubricity in a range of temperatures. The impact of storage temperature on deterioration in tallow quality was investigated over a period of one month. The available emission control systems have been reviewed and a solution choice has been made, based on legal and economic criteria. A summary of two thousand hours operation of the 800 kW generating set using neat fat is provided. The renewable electricity generation subsidising system in the United Kingdom has been reviewed. A basic feasibility study for the installed generating set was prepared and the highest tallow price at which electricity generation is profitable was determined.

The cleaning of food-based soils is highly relevant in domestic and industrial environments due to the costs associated with these operations as well as the significant consumption of time, water, and energy. Understanding the relationship between chemical and mechanical forces required to clean a surface is a critical step towards optimizing these processes. A complex twophase polymerized grease was developed and characterized with respect to its morphology, component distribution, and chemical composition. A thorough evaluation and physicochemical characterization of the cleaning process of this complex soil from a hard substrate was performed at two different length scales. Results showed that surfactants are more effective at weakening the cohesive interactions within the soil matrix and less effective in removing the adhesive bonds at the soil-substrate interface. A statistical model for cleaning efficiency was developed which described cleaning as a function of chemical and mechanical contributions. The effect of the chemistry on hydration and final cleaning performance was investigated through a definitive model screening and correlated to the tribological forces involved in the process. The model was shown to be applicable to several industrially relevant surfactant systems and revealed that hydration is the main factor driving cleaning of this two-phase soil.

In the first part, an economic scheme to smooth short periodic and heavily fluctuating wave power is proposed by controlling the inherent large amount of inertial energy of nearby offshore wind turbine systems (WTSs). The smoothing principle is that these WTSs are controlled to absorb the fluctuations of the wave power or release power opposite to them. The control challenge is that two objectives have to be achieved simultaneously: the rotor speed of a WTS has to be controlled against smoothing requirement whilst controlled to follow changes of wind speed to achieve wind power capture close to the maximum. To resolve this issue, Integrated Compensation Control is developed by adding two supplementary terms into the original maximum power point tracking (MPPT) control. In the second part, a method for short-term wind power smoothing is proposed by controlling wind turbines inertial energy. To achieve this, the designed power reference of a WTS includes two components: one component can approximately recover the original power trajectory of the MPPT control and the other can compensate the fluctuations of the former. In the third part, a new scheme to isolate and suppress forced oscillations is proposed. It controls the inertial energy of wind farms to timely release or absorb power opposite to the forced oscillating power from perturbation areas. Thus, the forced oscillations are prevented from propagating to the rest of power grid - isolated and the oscillating power in the disturbed areas is also reduced - suppressed.

This thesis is an investigation of different strategies for efficient development and optimization of radial-inflow turbines (RIT) for small-scale ORC systems. A novel methodology based on mean-line modelling, multi-level optimization and experimental study was proposed and validated for a small-scale compressed air RIT. Extending the proposed approach to organic fluids necessitated the use of real-gas equations. Deficiencies of constant turbine efficiency assumption that was commonly used in the literature were highlighted. A novel approach for integrated modelling of organic RIT with ORC coupled with genetic algorithm optimization technique was developed to alleviate the errors during fluid selection and cycle analysis and also optimize the ORC performance. A novel dual-stage transonic RIT was developed to further improve the ORC performance. The efficiency of such turbine was improved further using 3-D CFD optimization technique. Such optimization proved to be very efficient as it substantially improved the turbine efficiency of both stages by about 10%. CFD results for the optimized dual-stage turbine at design point showed the turbine efficiency of 87.12% and ORC thermal efficiency of 13.19%. Such results were considerably higher than the reported values in the literature and highlighted the effectiveness of the combined mean-line and CFD optimizations developed in thesis.

With increasing concern on the dwindling of the fossil fuel reserve and climate change, more and more effort has been focused on seeking green fuel to replace fossil fuel and mitigating the emissions of greenhouse gas (GHG). Biodiesel has attracted much attention for its sustainability, lower emissions of HC, PM and CO, and the diverse feedstock. In this study, diesel/diesel-like fuels were experimentally studied in terms of spray and combustion characteristics.