This research aimed to investigate the distribution, mobility and potential bioavailability of mercury in the Medway Estuary, Kent, UK, and the impact of feeding regimes on mercury concentrations in the food web, as well as the importance of liver as a storage organ for mercury within fish. Surficial sediment mercury concentrations were typical of an industrialised estuary, ranging between 18-1302 µg kg-1 (dry weight). Three sediment hotspots contained mercury concentrations which are likely to cause adverse affects to organisms. Porewater mercury concentrations ranged between <0.01-1.75 µg L-1, and were not correlated with mercury in the solid phase. The lowest partition ratio between mercury concentrations in sediment and porewaters was observed at four locations in the mid-stream and towards the mouth of the estuary (log Kd = <2). At these locations a greater fraction of total sediment mercury (sediment plus porewater) is likely to remobilise and potentially become more bioavailable. Mercury porewater concentrations are elevated in comparison with overlying waters, suggesting a diffusive release of mercury from the bottom sediments to the water column. The calculated diffusive flux was 6 kg year-1, demonstrating that mercury is mobile in this system. Mercury in sediment core samples ranged between 382-1888 µg kg-1 (dry weight). Dredging the Medway would release mercury from these more contaminated deeper sediments into overlying water, thus having potentially ecotoxic consequences. Within the cores, methylmercury concentrations ranged between 0.3-0.8 µg kg-1 (dry weight) and organomercury ranged between 2-48 µg kg-1 (dry weight). Mercury concentrations in fish flesh ranged between 0.01-0.63 mg kg-1 (wet weight), with all specimens being within the EU limit for human consumption.

This research presents the development of CityZoom UP, the first attempt to extend existing urban planning software in order to assist in modelling urban scenarios and setting up simulation parameters for Gaussian dispersion and CFD models. Based on the previous capabilities and graphic user interfaces of CityZoom to model and validate urban scenarios based on Master Plan regulations, new graphic user interfaces, automatic mesh generation and data conversion algorithms have been created to seamlessly generate input data for dispersion model AERMOD and CFD packages CFX and OpenFOAM. A key feature of CityZoom UP is the introduction of vehicular pollution source parameters in dispersion and CFD models, allowing the urban designer to assess the local impact of adding or modifying a building or group of buildings on the street air quality. Traffic emissions are modelled as sequence of point sources. CityZoom UP uses Atmospheric Dispersion model AERMOD to assess the dispersion of pollutants in large scale urban environments for strategic planning, quickly providing results for different alternatives of urban scenarios, meteorological and traffic profiles. Sensitivity and validation tests are performed and the results are compared to wind tunnel and real world tracer experiments from the DAPPLE campaign. For the first time in the available literature AERMOD is used to perform dispersion simulation using tracer emission data from mobile vehicular sources in a complex urban scenario, considering building wake effects. CityZoom UP also provides automated 3D meshing, including mesh refinement, identification of physical boundaries in the mesh, and automatic setup of CFD simulations of urban scenarios, for the detailed calculation of air flow and dispersion of pollutants in specific areas inserted in urban environments. These capabilities can greatly reduces the time necessary for the setup CFD cases, even if it does not affect the computational time needed to run the CFD simulations. Tests show how CityZoom UP can be used to model alternative scenarios for a given location, e.g. present situation and future scenario including a new tall building, and to easily automate the generation of different meshes for each scenario, based on boundary layer and size function refinement parameters. The present and possible future situations of a real world scenario in Porto Alegre are modelled as a show case for CityZoom UP. The capabilities to assist in modelling alternative urban scenarios and setting up AERMOD and CFD simulations based on those scenarios is demonstrated.

A method to treat contaminated land is stabilisation/solidification (S/S), which physically encapsulates and chemically stabilises the contaminants. The current knowledge on the behaviour of S/S systems is based upon scarce and incomplete data, mostly obtained from laboratory simulations or small scale trials of the technology. The field performance of S/S soils is largely unknown. The aim of this research was to improve the understanding of the long-term performance of S/S soils, by examining samples retrieved from eight full-scale remedial operations. The sites were selected to encompass a broad range of contaminants, binder systems, environmental exposures, and ages since the remediation. Conceptual models for each site were developed, based upon historical information from the literature. The models were used to identify the environmental loads, acting at the sites, and to predict their likely impact on the S/S soils. These impacts were considered by examining the microstructure, mineralogy, leaching behaviours and mechanical properties of the aged soils. Risk indicators for the performance of S/S soils were identified and they included reactions involving sulfates, carbonation, microcracking and the presence of weathered minerals. There was no link between the age of the S/S soils and degradation. The performance of the S/S soils was site specific and was influenced by the design of the remediation formulation, the implementation of the treatment and not least the environment of exposure. The behaviour of S/S soils is commonly compared to that of concrete. However, whilst the results suggested that some degradation mechanisms occur, properties such as permeability and unconfined compressive strength differed. The S/S soils were two orders of magnitude weaker and five orders of magnitude more permeable than normal concretes. Microstructural investigations revealed that although expansive phases developed with time in the SIS soils, there was no damage associated with them. According to their mechanical properties seven out of eight soils performed to their design criteria, up to 16 years after remediation. However, three sites failed to meet the limits following pass/fail leaching tests. This was due in part to the choice of leaching test carried out for the evaluation and the use of inappropriate remedial leaching limits, such as Drinking Water Quality values. However, the pH dependent leaching test showed that the contaminants were well immobilised in the old SIS soils and their release, at the natural pH of these soils did not exceed 1 mg/1. The acid resistance of the aged SIS soil was low to moderate and was mainly assured by the carbonates present. This fact will impact on the durability of SIS soils; however, estimates from the literature indicate that the acid resistance of carbonated materials would be exhausted in thousands of years. Based upon these results, the integrity of the soils had endured, and no obvious signs of impending failure were observed.

Accelerated carbonation involves exposing a material to a concentrated atmosphere of carbon dioxide, and can be used to treat hazardous wastes and soils and create new construction materials. The present work examines the use of accelerated carbonation to reduce the hazardous properties of wastes as a means of reducing the costs of disposal to landfill, and then develops the process to manufacture aggregate from the waste removing it from landfill disposal completely . A range of thermal wastes, including those from cement, metallurgical and paper processes, were found to be reactive with carbon dioxide. Many of these wastes are hazardous on account of their alkaline pH, which carbonation partially neutralizes, effectively allowing reclassification of the materials as stable non-reactive hazardous wastes under the Landfill Regulations. Cement and paper wastes were highly reactive with carbon dioxide, and were considered for use as cement substitutes to reconstitute non-reactive wastes into aggregate. Previous work had suggested that carbonation and pelletising were not compatible due to differing optimum conditions. This issue was investigated by considering the effects of the mix formulations and machinery parameters. The pelletising and carbonation processes require widely different moisture contents. The disparity is due to the need for total saturation of the material to form bonds between grains during pelletising, and an open pore network for carbon dioxide to penetrate. To achieve the two simultaneously, several methods were investigated. Chemical catalysts including sodium hypochlorite and sodium sulfite increased carbonation in a saturated material. However, curing the formed aggregates in carbon dioxide was found to be the most economic solution. A pilot scale process was developed based upon the laboratory results. A bespoke rotary carbonation reactor was developed to produce aggregate in bulk for commercial testing. Aggregate which was subjected to accelerated carbonation, has enhanced strength and durability compared to aggregate exposed to natural carbonation. The aggregate was successfully used to produce lightweight concrete with comparable strength to concrete made from commercial lightweight aggregate. Aggregate was also supplied for a research project to investigate the use of recycled materials as a horticultural growing medium.

The modelling of infiltration and moisture movement within a porous medium requires information on the moisture retention and hydraulic conductivity properties. In this study, the unsaturated hydraulic behaviour of a compacted waste sample based on the composition of Lyndhurst Landfill site in Melbourne, Australia was investigated in laboratory. Two fundamental aim of the study were to establish the moisture retention characteristics of Municipal Solid Waste (MSW) sample and measure its unsaturated hydraulic conductivity. In landfilled waste, the particle and pore size distribution, heterogeneity of waste composition and leachate chemistry complicate the determination of moisture retention and hydraulic conductivity. In this study the modification and use of a standard pressure plate apparatus was described which can be used establish moisture retention properties of samples of 230 mm in diameter. The experiments showed that the moisture retention characteristics of compacted waste sample were comparable to soils. It has been shown that water retention in waste is a function of its position relative to the phreatic surface, in other words, its hydraulic boundary conditions which will vary with elevation. Some difficulties and limitations of using this method were discussed. As with conventional inert soils, laboratory determination of unsaturated hydraulic conductivity is difficult and recourse is often made to analytical methods as those presented by van Genuchten (1980). One aim of this study was to compare the unsaturated hydraulic conductivity of MSW obtained using Passioura' s (1976) onestep outflow test method with predictions using van Genuchten's model. Good agreement is observed between the predictive model and experimental method for unsaturated hydraulic conductivities at low moisture contents but there is poor agreement at high degrees of saturation. This latter discrepancy is attributed to the difficulty of measuring retention properties of large pores at low suctions and the applicability of the van Genuchten model to such a material. Results also suggest that dual porosity exists within waste.

The ICSSWH (Integrated Collector Storage Solar Water Heater), apart from being the oldest is also the most economical means of solar water heating. The effect of modifications in the collector geometry has frequently appeared in the literature, and over the time, has resulted in different designs. These designs differ mainly on the site of installation as well as the target application. A novel design created by Professor T Muneer at Napier University, utilizes fins inside the storage tank to improve the heat transfer. The reported field tests of the fin type ICSSWH have indicated a 10 % improvement in the solar fraction compared to unfinned. As ICSSWH is the lowest cost, it presented a possible solution for the Scottish market where Energy Saving Trust estimates that 50% of hot water demand of a household can be met through solar water heating. In the present research program, two prototype collectors (one with- and one without fins) were fabricated at Napier University by the author. The collectors were then tested in the laboratory on identical experimental schemes to determine their respective performance. Simulations based on analytical modelling were then undertaken, using numerous experimental data for validation that were obtained during the course of the present work. A high degree of conformance was noted between the two. Furthermore, for a deeper insight, Computational Fluid Dynamics (CFD) analysis was performed. This research focuses on the qualitative and quantitative assessment of the heat transfer due to the fins. The difference in the performance with respect to the change in tilt angle was also studied. This study can therefore be utilised for developing solar water heating systems for any given location. Note that there is an intrinsic link between the latitude and inclination angle of the collector plate. The nocturnal loss from the collector is the principal factor that has inhibited the wide spread use of the ICSSWH. The remedies to abate this problem have therefore been attempted. In addition to that, the collectors have to be integrated with the domestic hot water supply system and plumbing considerations have to be incorporated within the overall design. The supply circuits were worked out and the measures for freeze and boil protection were devised. The optimization of any system is an intrinsic task particularly when several variables are involved. On the basis of the obtained results from simulations and experiments, the influential design variables were identified. The values for these variables which lead to the optimal design in terms of thermal performance were assessed while keeping the overall manufacturing cost of the collector as low as possible. Recommendations for future work have also been presented.

This thesis deals with the following aspects of renewable energy technology; solar energy modelling within the urban environment, performance of building integrated renewables including solar photovoltaics and micro wind technology. The development of hydrogen technology and electric zero emission transport is also reviewed. Incident solar irradiation models have been developed to accurately incorporate the effects of shading, in order to enable the detailed simulation and estimation of solar energy systems within the urban environment. Both the Integrated Slope Radiation Model (ISRM) and the Sky Radiance Distribution Model (SRDM) have been developed to use readily available horizontal sub-hourly or hourly solar global and diffuse irradiation data. Shading parameters caused by the surroundings, such as building and trees, can be incorporated into the models. A software package based on these models has been developed to allow the design and simulation of solar energy systems. Horizontal solar global irradiation data is readily available around the world. However, diffuse irradiation data is available to a lesser extent. To resolve this problem and enable the above mentioned incident solar irradiation models to be used throughout the world a simple regression set was developed between the diffuse ratio, k, and clearness index, kt, to enable the estimation of horizontal diffuse irradiation from its horizontal global counterpart. A review of building integrated renewable technology has been carried out. This includes the review of the performance of Edinburgh Napier University photovoltaic facade which has been in operation for over three years. Building mounted micro turbine technology is also reviewed. Performance analysis of three micro wind turbines installed on the rooftop of Edinburgh Napier University was undertaken, along with an analysis of the available wind regime observed at roof level. A software package was developed to aid the monitoring and analysis of both micro wind turbines and their observed wind regime. Hydrogen technology is reviewed as part of the development of Napier Hydrogen Research Facility, enabling the demonstration of hydrogen generation, storage and use from renewables. Finally, an analysis and comparison of a zero emission electric scooter with a conventional petrol car for use as urban transport was carried out. A driving cycle analysis was also undertaken to determine the environmental impact of both vehicles.

This research is mainly focussed on solar radiation in the UK. It can be divided into four main areas; evaluation of models, analysis of the relations between temperature and solar radiation, critical analysis of the projected future data for the UK and the improvement to the UKCP09 Weather Generator (WG). From the evaluations of models carried out, the Liu-Jordan model performs well for estimating the average hourly global and diffuse radiation. At the individual hourly level however, a number of problems were observed. Regarding clear- sky radiation models, for semi-arid climatic conditions Page model was found to be suitable and for humid climates Yang model is recommended. As for all-sky radiation models, the MRM and Yang model were selected. For the UK, the MRM was found to perform better than the Yang model. Furthermore, a study was carried out to analyse the relationship between temperature and solar radiation. The development of temperature-based mathematical models to obtain mean-daily irradiation was established. A procedure to decompose daily to hourly temperatures was evaluated with respect to world-wide locations and its performance found to be satisfactory. As part of the UKCP09/COPSE project, detailed analysis on the future projected data was carried out to critically evaluate sol-air temperature and the likely change that may occur in the key climatic variables, i.e. temperature, sunshine duration and solar irradiation. Drastic increase of sol-air temperatures and shifting trend of daylight illuminance were found. Furthermore, a sensitivity test was also carried out to analyse the effects of each input variables on sol-air temperature. As a result of the present investigations and communications with the UKCP personnel a new version of WG was released with appropriate modifications. A comparison of the now old- and new WG data sets has been made. Improvements in ratio of diffuse to global radiation and sunshine datasets were found.

No description available.

Wastewater activated sludge treatment plants are among the most common forms of biotechnological application. These plants breakdown influents of organic and non-organic matter using a complex bacterial consortia in an aerobic aqueous suspension. One of the most persistent and widespread problems associated with these plants is the formation of thick viscous chocolate coloured scums or foams on the surface of the aeration tanks of the plants. These foams can reach depths of 1.0-1.5 metres and can transfer to the secondary clarifiers and into open water sources. They not only reduce operational efficiency of the plants but they have also been associated with the transfer of pathogens such as Mycobacteria, nocardioform actinomycetes and the opportunistic pathogen Nocardia jarcinica. This investigation had two main aims: 1. To analyse two WWTP with very different characteristics to identify the causative organisms and factors of foaming in them both. 2. To design a sampling strategy for further investigations into foaming In this study the molecular techniques to permeabilise the actinomycetes (the probable foam causing organisms) and hybridise them with specific oligonucleotide probes for use in Fluorescent in situ hybridisations (FISH) were evaluated. In addition four novel 16S rRNA oligonucleotides were designed to detect Nocardia species in environmental samples. FISH using a nested set of probes covering Rhodococcus spp, Gordonia spp, Nocardia spp and the mycolata was evaluated for use in the detection and enumeration of target orgamsms in situ allowing the spatial make up of environmental filamentous flocs to be examined. The operational data from a large pharmaceutical waste water treatment plant was obtained which provided a comprehensive study of the day-to-day workings of the aeration basin over a three-month period, during which a foaming incidence occurred. This data was analysed statistically to find possible indicators of the causes of foaming. Several conclusions were made about the causes of foaming in this plant. An alternative PCR-ELISA methodology was devised to produce semIquantitative enumeration of actinomycetes within environmental samples. A sampling regime was devised for the further study of foaming in activated sludge systems. This regime incorporates the use of FISH; PCR-ELISA to identify and characterise the bacterial consortia within the mixed liquor suspended solids of activated sludge plants, and analysis of the physical characteristics of the plants. A combination of these techniques will eventually allow not only control of foaming but also prevention.