The performance and sustainability of ground source heat systems is dependent on the thermal behaviour of neighbouring ground. This thesis describes a comprehensive experimental and numerical investigation into the ground behaviour in response to horizontal ground source heat systems. Experimental investigations comprised of a field-scale monitoring scheme, designed and implemented in a horizontal ground source heat system providing space heating to a domestic property located in Mid-Wales, UK. A high resolution ground temperature data-set has been compiled over a 13 month period via 112 thermistors buried in the ground. Further data-sets representing the climatic variables and heat pump behaviour were also compiled over the same period, facilitating a thorough investigation of the ground behaviour in response to heat extraction at the site. Soil properties were also measured at the site as part of a larger site investigation undertaken. The numerical model applied is a coupled thermal-hydraulic (TH) model previously developed at the Geoenvironmental Research Centre (GRC). The GRC’s current model was extended to include developed boundary conditions for the TH simulation of horizontal ground source heat systems, describing the soil’s interaction with the ground-loop and atmosphere. Developments were subject to rigorous validation including comparisons with ground-data collected at the experimental site. The validated model was applied to investigate the long-term ground behaviour at the monitoring site and the effects of different surface materials on the ground behaviour including the recharge process. Finally, the model was applied to investigate the validity of an existing design code for ground source heat system design. The resolution and duration of the collated data-set facilitated extensive analysis, including a thorough investigation of the ground thermal distributions resulting from heat extraction and recharge. Findings indicated unsymmetrical distributions, highlighting potential avenues for system optimisation. Further to this it can be said that the data-set, in its own right, is a significant contribution to the scientific community and is able to provide a means of validation for future models. Results from the numerical investigation indicated that the ground thermal behaviour exhibits an annual cyclic pattern after approximately 3 years. From a holistic perspective, the results demonstrate that horizontal ground source heat systems can provide a sustainable means of providing space heating. Further long-term studies investigating the effects of surface materials show that more thermal energy can be sustainably extracted from systems with urban surface types (i.e. asphalt and brick). Investigations into an existing design code revealed that a ground-loop designed to meet the loads of the monitoring site resulted in unsustainable heat extraction, in doing so demonstrating the simplification of ground-loop burial depth within the current design process. Knowledge regarding the ground response to horizontal ground source heat systems has been furthered through the collection and analysis of field-scale data within this study. Further to this, the boundary developments and validation undertaken have allowed for a more thorough investigation of the long-term ground behaviour than previous studies.

Several methods of river water quality assessment techniques have been introduced. Among the most commonly used are the water quality index system and classification scheme. These two systems are designed to simplify the huge amount of water quality data down to its simplest form, while retaining the essential meaning of the information. They offer the means for measuring the effectiveness of pollution abatement strategies by comparing the status of water quality both temporally and spatially. In this way, it is useful for management purposes, especially in determining priorities for resource allocation and planning of new development areas. The water quality index system and the classification schemes currently available, however have some limitations in their structural design. They often exhibit inherent loss of information, are complex and may involve subjective judgement in their interpretation. However, because of the critical issues on water pollution and the scarcity of water resources, these systems are being applied despite of these limitations. The current situation is that, different countries are applying different models of water quality assessment system. Based on the limitations of the existing assessment systems, it is appropriate to explore other approaches that can be more flexible, robust to noisy data, and adaptable to new form of environmental data, in order to provide direct and prompt results for classifying of river water quality. One avenue for research is that based on Artificial Neural Network (ANN). Artificial Neural Network comprises of several techniques. One of this technique that is widely being used is the Back-Error Propagation (BEP). BEP of ANN was used in this research in conjunction with the Interim National Water Quality Standard (INWQS) data for Malaysia. The findings of the study shows that the classification results based on the evaluation of the water quality variables were good when compared with the results obtained from other water quality classification models, which include: the Department of Environment Water Quality Index (DOE-WQI), the Harkins'-WQI, Mahalanobis Distance Classifier, Maximum Likelihood Distance Classifier and the Decision Tree Classifier. The accuracy for BEP of ANN was found to be 86.9% and correlated well with all of these five models. The highest correlation was, with the Mahalanobis Distance Classifier and the DOE-WQI. The analysis on sensitivity shows that the BEP of ANN was sensitive to Dissolved Oxygen, a condition similar to the DOE-WQI model. Comparisons were made with two types of BEP of ANN architecture, a simple network with less number of hidden nodes and a relatively complex network with more hidden nodes. It can be concluded from the analysis that a small and simple network performed well with large samples and with test data that are widely distributed than the complex network with more hidden nodes. Using the same model, different approaches were used in evaluating the classification of water quality were applied, such as the used of the land use variables and hydrological features (LUVHF) to replace the water quality data. Using these variables, the performance of the BEP of ANN in classification of water quality was low (24% and 31%). However, its performance can be improved, if more samples with wider range of LUVHF were used. Throughout this study, the BEP of ANN model has shown some remarkable achievements. In view of these, several knowledge contributions have been made. The first contribution is the flexibility of the system approach and operationally simple to perform. Secondly, it provides a practical approach in classification of river water quality, such that through a single network computation of a sample, the results are presented promptly as the probability value and the class grade value. The third contribution is that the water quality can also be classified based on the land use variables and hydrological features, without dependence on water quality data. This approach is suitable for remote areas, where accessibility is relatively difficult.

The feasibility of using CFD to model the dispersion of pollutant in the near wake of a model vehicle was investigated through a series of experimental and computational studies. The near wake structure of the MIRA 33% scale reference vehicle (fastback) was measured using Particle Image Velocimetry (PIV), and hotwire anemometry and the dispersion of a tracer measured using Flame Ionisation Detectors (FIDs). The experimental data not only provided insight into the dispersion character of the model vehicles's near wake but more importantly produced data for the validation of the numerical simulations of the measured near wake and dispersion fields. The numerical simulations of the near wake flow field were conducted using the CFD code STAR-CD with the standard, RNG, Chen and nonlinear (quadratic) k- e models in combination with Upwind (UD), Linear Upwind (LUD) and the Monotone Advection and Reconstruction (MARS) differencing schemes. Validation showed the predicted flow field to be in good agreement with the measured flow field. Using the numerical flow field predictions as a foundation the dispersion of a passive gaseous pollutant was simulated by modelling the dispersion of scalar quantity released into the computational domain using a fluid injection technique. The numerical predictions of both mean velocity and concentration fields were validated against the experimental data using various statistical validation techniques. Several short investigations into the influence of vehicle speed and exhaust mass flow rate were also conducted to further assess the applicability and use of the technique in investigating dispersion in the near wake of a vehicle. Relative successes in both the velocity field and dispersion simulations were demonstrated in making predictions of the mean velocity and concentration fields. However there is clearly the need for more development and in particular the application of time-dependent techniques for the underlying velocity solutions in order that peaks in mean concentration resulting from build-up due to unsteadiness in the flow field are fully captured. Nevertheless the study demonstrated the potential for the use of STAR-CD to investigate and understand in more detail the dispersion of pollution close behind a road vehicle and possibly assess the concentration levels, at the road side of different pollutants released.

Traffic-related air pollution is now a major concern. The Rio Earth Summit and the Government's commitment to Agenda 21 has led to Local Authorities taking responsibility to manage the growing number of vehicles and to reduce the impact of traffic on the environment. There is an urgent need to effectively monitor urban air quality at reasonable cost and to develop long and short term air pollution prediction models. The aim of the research described was to investigate relationships between traffic characteristics and kerbside air pollution concentrations. Initially, the only pollution monitoring equipment available was basic and required constant supervision. The traffic data was made available from the demand-responsive traffic signal control systems in Leicestershire and Nottinghamshire. However, it was found that the surveys were too short to produce statistically significant results, and no useful conclusions could be drawn. Subsequently, an automatic, remote kerbside monitoring system was developed specifically for this research. The data collected was analysed using multiple regression techniques in an attempt to obtain an empirical relationship which could be used to predict roadside pollution concentrations from traffic and meteorological data. However, the residual series were found to be autocorrelated, which meant that the statistical tests were invalid. It was then found to be possible to fit an accurate model to the data using time series analysis, but that it could not predict levels even in the short-term. Finally, a semi-empirical model was developed by estimating the proportion of vehicles passing a point in each operating mode (cruising, accelerating, decelerating and idling) and using real data to derive the coefficients. Unfortunately, it was again not possible to define a reliable predictive relationship. However, suggestions have been made about how this research could be progressed to achieve its aim.

Despite water being apparently abundant, up to half of the world’s population is faced with water crises which is growing at an alarming rate most especially in developing countries such as African countries where both physical and economic water scarcities prevail. Thus with the abundant salty water and solar intensity in the regions or seasons when water is mostly scarce, solar powered desalination presents an attractive and promising solution towards availability of clean water. A unique and simple solar desalination system has been developed. The system which based on humidification/dehumidification process is a low cost solution and very competitive with conventional desalination systems. It can be used to provide clean water to the over one billion population who have no access or have water shortages which threaten their health and economies. The developed solar desalination system consists of a purposely designed concentrating solar collector and the desalination core which consist of the humidification and dehumidification chambers. The novel concentrating v-trough solar collector which has its focal point at the bottom of the concentrator provides enough thermal energy required to heat up seawater which is then pumped and sprayed to humidify the incoming air in the humidification chamber. The humidified air enters the dehumidification chamber and is cooled by the incoming cold seawater. The moisture is condensed out and the pure water is accumulated at the base of the chamber, and the dehumidified air is discharged to the outside. The key point is the psychrometric energy re-use, most of the energy is from the condensing of the moisture in the carrier gas. Both theoretical analysis and experimental tests were carried out and good water output up to 20kg/h and COP around 3 was obtained. This would require 8m2 of the newly designed v-trough collector operating at 100°C at 1000W/m2 solar intensity. And economic and environmental analysis showed that the solar powered desalination system can achieve a 6 year payback period when compared with when driven by electricity and also a saving of up to 4730 kgCO2 per year. The system can be manufactured from inexpensive plastics rather than exotic and expensive metals. It can easily be sized and scaled to location’s needs, can be operated in diverse geographies unattended on a continuous basis and require minimal maintenance.

This work examined the impact of soil organic matter (SOM) on the sorption, phase distribution and transport of ethanol and butanol blended gasoline vapours after release. Microcosm and mini-lysimeter experiments were conducted using sand with varying SOM and moisture contents. Synthetic gasoline alone and blended with 10 - 20% ethanol and 10 - 20% butanol by volume, referred to as UG, E10 - E20 and B10 - B20, respectively, were used. Results from the UG were used as the benchmark to assess the impact of ethanol and butanol on gasoline compounds. The findings of this work illustrate the likely behaviour of gasoline compounds at the beginning times of a gasoline spill or leak. The addition of alcohol to gasoline altered the behaviour of the gasoline compounds in the vadose zone in several ways. Firstly, it reduced the sorption of the gasoline compounds by soils. This effect was greatest on the first day of a spill and affected the gasoline compounds in decreasing order of hydrophobicity. Secondly, it altered the mass distribution of the gasoline compounds between the vadose zone phases to higher mass compounds in the mobile phases (soil air and soil water) and lower mass compounds in the immobile soil solid phase, suggesting higher risk of groundwater contamination with an increasing content of alcohol in the gasoline. Thirdly, it increased the vapour phase transport of the gasoline compounds from the source zone to the groundwater zone. These three impacts were generally greater for ethanol than butanol. The sorption coefficients (Kd) of E20 gasoline compounds were reduced by 54% for alkanes, 54% for cycloalkanes and 63% for the aromatics, while the Kd of B20 gasoline compounds decreased by 39% for alkanes, 38% for cycloalkanes and 49% for aromatics. This implies that the use of ethanol as gasoline oxygenate could result in greater risk of groundwater contamination with gasoline compounds than the use of butanol after spills. The SOM enhanced the sorption of alcohol-blended gasoline compounds in soils. This impact was similar for ethanol and butanol blended gasoline as the Kd of B20 and E20 were equally increased by 7 times for aromatics, 4 times for cycloalkanes and 2 times for alkanes, for 0 to 5% increase in the SOM fraction of sand. Although SOM enhanced the sorption of alcohol-blended gasoline, its sorptive capability was not fully realised compared with the sorption of the UG compounds. Also, it did not alter the order of groundwater contamination risk for the ethanol and butanol blended gasoline. Thus, the Kd values for all gasoline compounds for all the SOM fractions tested, including 0%fom, 1%fom, 3%fom and 5%fom, were in the order of UG>B20>E20, indicating greater risk of groundwater contamination for the ethanol-blended gasoline after a spill or leak regardless of the SOM content of the soil. The increase in the water content of soil reduced the sorptive capability of SOM and affected the overall mass distribution of gasoline compounds between the soil solid, soil air and soil water phases estimated with values of Henry’s law constant from the literature. This indicates that the degree of gasoline retention in the vadose zone by SOM could differ during the dry summer and wet winter seasons. This effect was greater for ethanol than butanol. Thus, in all seasons, the amount of gasoline compounds retained by SOM in the vadose zone is likely to be higher for butanol-blended gasoline than ethanol-blended gasoline. Overall, this study indicates that the use of high ethanol volume in gasoline to combat climate change may put the groundwater at greater risk of contamination after spills or leakages from storage. Therefore, to successfully reduce greenhouse gases emissions via high alcohol volume in gasoline and still protect the world’s groundwater resource, this study suggests the use of butanol is more benign than ethanol.

This thesis describes the development of a system to assist the design of long-term remediation strategies for radioactively contaminated land. Existing radiological models, that estimate the uptake of radionuclides by plants and the doses arising from exposure to external radiation, were combined with a spatially implemented food-chain model, to allow the temporal and spatial variation of radionuclide transport through the terrestrial environment, and the resulting doses of exposed human populations, to be estimated. Doses are estimated using a novel method for the simulation of human populations, which includes the generation of sub-populations by Monte-Carlo sampling and consideration of the geographical origins of consumed food products. Various simulated radiological countermeasures have been incorporated into the system (e.g. clean-feeding of livestock), allowing the effects of potential remediation strategies to be assessed. Furthermore, a method has been developed which efficiently identifies the optimum set of countermeasures for a given scenario according to a defined merit function using cost benefit analysis, which can be extended to include terms that account for the preference for averting high levels of individual dose, and the social costs of a number of countermeasure side-effects (e.g. disruption of normal daily life). To assess the applicability of the system, it was used to evaluate potential remediation strategies for hypothetical, large-scale nuclear accidents within two contrasting case study sites (Cumbria, UK and Zaragoza, Spain). In both case studies the system successfully identified optimal remediation strategies which were, according to the defined merit function, significant improvements upon simple food and dose rate restriction strategies.

Carbon dioxide capture and storage by mineralisation (CCSM) is considered to be an alternative solution for reducing anthropogenic C0₂in some regions, where geological storage is not possible or considered uneconomically viable. However, low efficiency of mineral dissolution and use of unrecyclable additives are two key barriers for the development of CCSM. A novel CCSM process with recyclable ammonium salts is proposed to overcome these barriers in this study. This process integrates mineral carbonation with C0₂capture by employing NH₃, NH₄HSO₄and C0₂containing ammonium salts in the capture step, mineral dissolution and carbonation steps, respectively. The NH₄HSO₄ and NH₃can then be regenerated by thermal decomposition of (NH₄)₂SO₄, which is the by-product from the process. The use of C0₂ containing ammonium salts as the source of C0₂can avoid desorption and compression of C0₂, which account for 70 % of the total energy consumption in the whole CCS chain. In this work, a CCSM process route at low solid to liquid ratio (50 g/I) was experimentally investigated to validate the process concept. It was found that the dissolution efficiency of magnesium (Mg) can achieve 100 % by using NH₄HSO₄and the carbonation efficiency can reach 96.5 % by using CO₂containing ammonium salts from the capture step and addition of aqueous NH₃. Three products, including Si rich residue, Fe rich residue and pure hydromagnesite were obtained from the process. The TGA studies reported that the regeneration efficiency of NH₄HSO₄ and NH₃ in this process was 95 %. Both dissolution and carbonation efficiencies achieved in this work are higher than the values reported in previous work. In order to reduce the water usage, a CCSM process at high solid to liquid ratio (200-300 g/I) was developed. It was found that the dissolution efficiency of Mg was 64 and 72 % at 200 and 300 g/l, respectively. The increase of dissolution efficiency with a solid to liquid ratio could be explained by the removal of passive product layer caused by particle-particle interaction. At a solid to liquid ratio of 300 g/l, the highest carbonation efficiency achieved was 65.4 %. Magnesite instead of hydromagnesite was found after carbonation due to the CO₂ pressure caused by the decomposition of ammonium salts above 70 °C. Additionally, the carbonation efficiency was doubled by using (NH₄)₂CO₃compared to that using NH₄HCO₃. A preliminary evaluation was conducted to estimate the OPEX, including energy consumption, chemical costs and feedstock cost, based on the experimental results from the two process routes developed. In order to get low OPEX, the optimization process conditions, such as solid to liquid ratio and reaction time, were determined. Then, experiments at these optimized conditions were conducted. The dissolution efficiency of Mg from serpentine with particle size 75-150 pm using 2.8 M NH₄HSO₄at 100 g/l solid to liquid ratio for 1h was around 80 %. The carbonation efficiency was 96 % when the molar ratio of Mg: CO₂ containing NH⁴+ salts: NH₃was 1: 1.5: 2. Thus, the mass balance of the process showed that 3.0 t' of serpentine, 0.2 t of NH₄HSO₄and 0.1 t of NH₃ were required to sequester 1t of CO₂and produce 1.9 t of magnesite. Moreover, 1.7 t of high Si content (46.9 wt. %) and 0.3 t of high Fe content (60 wt. %) were produced. Finally, a cost evaluation study including CAPEX and OPEX was made using Aspen plus software to simulate the optimized CCSM process with recyclable ammonium salts for a 100 MW coal-fired power plant. For the input of 60 t/h CO₂, 93 % of them can be sequestered by the process with 29.5 % energy consumption and the total carbon capture and storage costs was 71.8 US$/t CO₂sequestered, excluding the product sale.

Sugar factories are a significant source of water pollution, particularly in developing countries such as Pakistan, where the sugar industry is the second largest after tanneries. The wastewater is disposed of untreated to the environment, since traditional wastewater treatment processes are capital-intensive, energy-demanding and complex in operation. The common approach is to use waste stabilization ponds or lagoons mostly operated on complete retention basis. This work is an attempt to highlight the possibility of effectively applying wastewater lagooning process utilizing the inherent organic contents of sugar factory wastewater with the aid of an algae-bacterial consortium (ABC) to investigate its capacity to utilize this resource to produce renewable fuel while de-polluting wastewater rather than it being a liability to be disposed of. A lagoon photo tank (LPT) resembling a prototype raceway lagoon was designed and used to carry out mass cell cultivation on a sugar-oriented medium for the assessment and inter-optimization of the process conditions such as temperature, incident light (IL), pH, dissolved oxygen (DO). The evaluation of the process performance was observed via the analyses of parameters such as chemical oxygen demand (COD), total organic carbon and cell mass growth. The first part of this study was related with the baseline assessment of LPT process conditions using distilled water as well as sucrose solution or sugar water to establish basis for a priori analysis of simulated sugar factory wastewater (SSFW) carried out in the second part. The suitability of the dosing of copolymer Polyacrylate polyalcohol was optimised through a series of trial runs to aid in the immobilization of mono or mixotrophic cultures of green algae Chlorella Vulgaris and bacteria Pseudomonas Putida at the surface of LPT in order to influence reduction in the organic concentration of SSFW. This research study has contributed to the knowledge base of the concerned area of study with respect to hitherto unknown application of copolymer Polyacrylate polyalcohol, which showed viable characteristics in the cultivation medium in terms of cell immobilization at the surface of LPT resulting in the formation of growth-conducive copolymer-algae matrices leading to the rapid growth of the cell mass with increased process efficiency. This process optimisation resulted in SSFW depollution by around 89% along with energetic biomass growth with a calorific value of 27 kJ g1 and at an optimum growth rate of 1.2 d1 suggesting towards the potential of copolymer addition in the system to enhance the efficiency of the organisms inducing optimum substrate utilization.

The problem of water pollution has been an environmental concern for many years. Numerous researchers are looking for an effective method to solve this issue. Heterogeneous photocatalysis, using a semiconductor as a catalyst, is a promising method for the destruction of water polluting pesticides. This method has been called the Advanced Oxidation Process (AOP) which is one of the techniques for water treatment. Titanium dioxide (TiO2) is the most widely accepted photocatalyst because it is non-toxic, stable to photocorrosion, low cost and can potentially work using sunlight rather than artificial sources of light. When titanium dioxide is illuminated by UV radiation, the absorption of photons of energy is then equal to or greater than its band gap width. This artefact leads to the formation of conduction-band electrons and valence-band holes on the surface of TiO2, which yield hydroxyl radicals, the primary oxidising species needed for the photocatalytic degradation of pollutants. Supercritical water hydrothermal synthesis (ScWHS) is one of novel approaches for nanoparticle manufacture which involves the mixing of an aqueous metal salt stream with a supercritical water stream to produce nano-sized metal oxide particles. The engineering design for the mixing of these two fluids is critical and a novel nozzle reactor has been developed at the University of Nottingham that can produce high quality particles with an excellent control over particle size and particle size distribution. By application of this technique, titanium dioxide (TiO2), in nanoparticle form, was produced and used for the photocatalytic treatment of wastewater. In this thesis, the photocatalytic degradation of the three pesticides - isoproturon, simazine and propazine - was measured using 3 different types of reactors: thin film fixed bed reactor (TFFBR), a stirred reactor, and a fluidised bed photoreactor. Various conditions were used: for example without UVC and UVA illumination, with commercial TiO2, with the synthesised TiO2, without any photocatalyst, low concentration, high concentration, and at different TiO2 concentrations. The optimum TiO2 concentration for the treatment of the three chosen pesticides was equal to 5 g litre-1. The efficiency in decreasing the pesticides concentration of the synthesised TiO2 (from ScWHS technique) with all three types of reactors was lower than that of the commercial titanium dioxide (P-25 TiO2). The fluidised bed reactor appeared to give the highest performance amongst three reactors.