Contamination of ecosystems by xenobiotic substances has led to significant negative impacts on the ecologies and on the health and economic livelihood of the human populations in affected environments. Bioremediation, particularly microbial bioremediation, has proven to be a safe, low-cost and environmentally friendly method for remediation of such areas. However, a lack of complete understanding of the metabolic, enzymatic and cellular processes involved has made it difficult to model and predict outcomes of field processes. The ability of researchers to make critical decisions capable of influencing the direction and outcomes of these processes is also hampered. This study outlines the results of a survey and describes the electronic Microbial BioRemediation (eMBR) web portal, designed to improve collaboration in the bioremediation research community. It describes the structure, algorithms and output of three bioinformatics resources developed and deployed via the portal. eMBRLitMine addresses the problem of identifying which microorganisms would be suitable for remediating sites contaminated by named compounds. It combines named-entity recognition algorithms, a mySQL database, graph rendering technologies and Perl scripts to create, from the vast information available within published literature, a statistical co-occurrence matrix which it uses to infer possible associations between microorganisms and particular contaminants. This provides valuable insights into possible bacteria/contaminant relationships and highlights bacterial species that could be used in remediation of specified contaminants. eMBRCatalogue is a moderated and searchable database cataloguing bioremediation case studies. Implemented as an eXtensible Markup Language (XML) database employing a user-generated-content framework, it provides background knowledge necessary for planning and execution of bioremediation activities. Developed following the construction of a comprehensive metabolic biodegradation network, eMBRHelper enables the delineation of possible biodegradation pathways for named contaminants. By integrating relevant chemical, enzymatic and genomics information, it attempts to model the interplay between contaminants, enzymes, microorganisms and degradation pathway, enabling researchers to make informed decisions for improved outcomes, particularly for remediation exercises involving bioaugmentation. The study also analysed usage of the portal and resources, made recommendations for future developments and highlights avenues for further informatics support for the bioremediation research sector.

Environmental fate of pollutants is paramount to their bioavailability, and as such their potential toxicity. Soil bound fractions of persistent organic pollutants (POPs) such as chlorobenzenes are far greater than in any other environmental compartment. This thesis investigates the potential for volatilisation flux of dichlorobenzene (DCB) from soils under planted and unplanted regimes. It was found that volatilisation, not mineralization, is the main route of DCB removal from soil systems. It was also found that planted systems resulted in a significant increase in volatilisation flux from DCB contaminated soil, in comparison to unplanted systems. It is concluded that the plants have two main interactions with the soil that may lead to this increased volatilisation. These are: (i) the plants transpirational influence dries out the soil; (ii) aromatic acids are released by the plants into the rhizosphere in the form of root exudates. It is shown in this thesis that drier soil has increased rates of volatilisation to the atmosphere than wetter soil. It is also shown in literature (Xing and Pignatello, 1998) that aromatic acids released by plant roots as exudates competitively bind to SOM resulting in the displacement of DCB that may subsequently be volatilised from the soil. Both of these factors in combination explain the resulting flux of volatiles from the soil under planting. It is of critical important to recognise volatilisation as a main route of POP flux from soil systems. Many previous studies may have overlooked volatilisation fluxes from soil in favour of the opinion that mineralization is the main route for removal. This may have important implications for the phytoremediation of contaminated soils.

The performance of the microbiologically-based tool kit employed in this study was critically evaluated for its ability to monitor the progress of hydrocarbon bioremediation. Different hydrocarbon remedial strategies (nutrient amendment, turning and inoculation) were applied to real hydrocarbon contaminated soil and the treatment effects monitored over a period of 60 days. The overall results of the tool kit evaluation showed that hydrocarbon biodegradation was clearly nutrient limited. The combination of turning and nutrient treatments were demonstrated to be more effective in increasing the rate of hydrocarbon biodegradation (as well as mediating a reduction in soil toxicity) than any single treatment. Although the chemical analysis methods demonstrated a significant reduction in hydrocarbon concentrations in the non-nutrient amended biopile microcosms, the biosensor assessment showed an increase in soil toxicity. Hence, an evaluation of hydrocarbon bioremediation based on analytical methods alone is not always indicative of a reduction in soil toxicity. The tool kit was further applied to biopile microcosms to identify constraints to hydrocarbon bioremediation. Soil matric potential was selected as a potential constraint to hydrocarbon bioremediation because of the great importance worldwide of this environmental control. Four different matric potentials (corresponding to a range of 20%, 40%, 60% and 80% soil water holding capacity) were assessed over a period of 40 days. The overall results from the use of the tool kit showed a strong positive correlation between the rate of hydrocarbon biodegradation and an increase in the soil matric potential tested. The increase in the rate of hydrocarbon biodegradation was also associated with a significant reduction in soil toxicity. Soil matrix was chosen as another potential constraint controlling the rate of hydrocarbon biodegradation. Bioremediation was greatest in the intermediate textured sandy loam (Insch soil). The slowest bioremediation rates were associated with the fine textured clay loam (Cruden Bay). Intermediate rates of biodegradation were associated with the coarse textured loamy sand (Boyndie soil). The chemical analysis showed a significant reduction in the overall hydrocarbon concentrations in the Cruden Bay soil (CB), but the toxicity biosensor assessment showed an increase in soil toxicity. Therefore, an assessment of hydrocarbon bioremediation based on chemical methods alone is not a sound approach, as hydrocarbon reduction does not always correlate with a decline in soil toxicity. The employment of the microbiologically-based tool kit to evaluate and monitor the performance of hydrocarbon bioremediation, complementing standard chemical methods, offers a  powerful new approach as chemical monitoring alone does not provide an adequate assessment of the process of hydrocarbon bioremediation.

A number of sustainable and economically viable treatment methodologies have been developed and optimised to combat environmental pollution problems associated with the diversity and scattered nature of industries in Pakistan. The use of both electro-precipitation and electro-oxidation processes are shown to lead to the removal of dyes from textile effluent streams originating from various operations. The use of the electro-precipitation process, however, leads to a secondary disposal problem because sludge produced has to be disposed of safely. The use of an electrooxidation process does not produce sludge but is unable to remove some of the organic impurities from industrial textile effluent. Both processes do, however, result in colour removal from dye effluents with the degradation of dyes during electro-oxidation proceeding through the formation of different intermediate species before mineralization leading to complete mineralization in 30-40 minutes. Ames tests confirm that the treated effluent streams from both electro-precipitation and electro-oxidation processes are non-mutagenic. The electro-Precipitation process with mild steel anodes is also be used for the treatment of leather effluent streams to remove chromium by producing a mixed Cr(III) / Fe(III) hydroxide sludge. The same treatment process was successfully used for the simultaneous removal of dyes and chromium from mixed textile/leather effluent streams. The electro-precipitation process developed has been successfully tested on pilot scale at a textile mill in Faisalabad, Pakistan. A number of transition metal supported catalysts were shown to be ineffective in the oxidation of volatile organic compounds. For this reason a method of preparing platinum group metal catalysts on inert supports at low temperatures was developed and used to oxidise toluene, as an indicator of volatile organic compounds. The preferred catalyst support is y-A1203 which can be in the form of spheres or washcoated monoliths. In the case of y-A1203 spheres and the y-A1203 washcoated monolith complete oxidation of toluene was achieved at the relatively low temperatures of 236 and 2680C. A number of novel room temperature ionic liquids (RTILs) were synthesised, characterised and their potential application for selective extraction of copper from industrial wastes is also reported. The solubility studies of different metal oxides in the RTIL, 1-(2-cyanoethyl)-3-methylimidazolium bromide, show that it can be used for the selective extraction of copper from industrial waste samples containing other metal oxides. This RTIL has the ability to selectively dissolve, copper, copper oxide and copper sulfide when the reaction is carried out in the presence of water.

Selective Extraction and Recovery using Volatile Organic compounds is an emerging technology developed during the 1970s. This process can achieve the extraction of heavy metal contaminants from a matrix using a volatile organic reagent which passes through the feed material and reacts selectively with the desired metal salt, producing a volatile metal complex, removed from the matrix by a carrier gas. Such complexes may be decomposed to produce a pure metal product and regenerate the organic reagent for recycle. Previous studies demonstrated the possible extraction of nickel from low grade laterite ores using ß-diketones (2,4- pentanedione (Hacac)) and Schiff bases (bis(pentan-2,4-dionato)propan-1,2-diimine (H2pnaa)). The current research is directed towards the selective extraction of different metals such as zinc, lead, cadmium, molybdenum, and vanadium from contaminated sediments and industrial wastes (Orimulsion ash, Municipal Solid Waste fly ash (MSW), Pulverized Coal Combustion technology fly ash (PCC)). New extractants and their metal complexes have been synthesised to determine their thermal stability and their volatility. Of those synthesised the metal complexes of tetra-propyldithiophosphoramide (Hprps) are the most thermally stable. Using a thermogravimetric analyser the reaction kinetics of the SERVO process have been studied. Equipment to study the SERVO process on a laboratory scale has been designed and constructed. This equipment has been used to study the extraction of metals from four different matrices (sediments, Orimulsion ash, and two types of fly ash) using three different extractants, with promising results. These sources have been ranked from the best to the least applicable for the technology: Orimulsion ash > sediments > MSW fly ash > PCC fly ash. Of the three extractants studied, Hacac, H2pnaa and Hprps, the latter is the most efficient in terms of the range of metals which can be extracted, the volatilisation temperature, the extent of degradation and reaction time, but unfortunately is also the most expensive. For the fly ashes, of the three ligands studied, Hprps is the preferred extractant followed by H2pnaa. Hacac is not recommended for these sources because extraction is too low.

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Airborne particulates are one of the most complex air pollutants and considerable concern surrounds their environmental impact especially with regards to human health. An investigation of the efficiency of various total inhalable and respirable dust samplers has been conducted to identify the most convenient way of collecting dust particles to examine their physical characteristics. The efficiency of a variety of dust samplers were investigated using limestone dust clouds generated inside an environmental dust chamber. Various sampling periods were employed to establish dust concentrations in the environmental dust chamber. The experimental dust cloud was found to contain on average 55.74 % of respirable dust as defined by different instruments while a consistent dust concentration of approx 200 mg/m3 was repeatedly produced. The methods for collecting and estimating airborne asbestos fibre concentrations were studied and found to be extremely limited. Standard optical techniques grossly underestimated both airborne fibre concentrations and respirable dimensions of fibres. The size and dimensions of respirable asbestos fibres are defined by their ability to gain access to the lungs and there is no instrument or technique available at present, which will allow collection and estimation of respirable fibrous dust clouds. A comparison of coal dust particles with similar particles retained in the lungs has shown a difference from the predicted respirable fractions as proposed by the British Medical Research Council (BMRC) and other conventions. Respirable dust sampling instruments may therefore be under sampling larger particles. The difficulty in estimating the characteristics of airborne particulate material has been demonstrated by illustrating urban particulate collection and analysis. The extremely large differences in terms of physical size, and aerodynamic properties of dust particles formed by different materials have been demonstrated.

Nuclear waste streams consist of a diversity of physical and chemical forms, requiring a toolbox approach in the application of materials to their disposal. Solid uranium metal wastes constitute a disposal challenge due to their tendency to oxidise, making encapsulation within cementitious waste packages for storage potentially troublesome. MKPC (Magnesium Potassium Phosphate Cement) is being considered as an alternative to Portland cement for U-metal encapsulation due to the potential for lower free water content, lower internal pH and the micro-encapsulation of radioactive isotopes as low-solubility phosphate minerals. In this work the development and characterisation of MKPCs optimised for U-metal encapsulation was undertaken. This included the investigation of MKPC property development under both near ambient and elevated temperature conditions, the performance of MKPC/U-metal wasteform corrosion trials utilising temperature elevation (to 30, 40 and 50 °C) for the acceleration of chemical kinetics, and assessment of the impact of dehydration treatments (at 50, 80 and 110 °C) on the cement properties. In general MKPC exhibited excellent processing and mechanical properties. Other significant outcomes of the work include, firstly, the determination that uranium corrosion rate dependencies in MKPC are dominated heavily by the presence of water over other chemical effects, with an anoxic activation energy of 68 ± 6 kJ/mol. Secondly, the development of a methodology for determining the bound water content of MKPC, which allowed the calculation of the extent of reaction. This enabled analysis yielding empirical strength-porosity and kinetic models of the material, capable of facilitating improved mix design for the tailoring of MKPC properties. Finally, the instability of the K-struvite matrix toward dehydration at temperatures of ≥ 72 °C has been recorded. The work concluded that MKPC has many properties which make it suitable as a general encapsulant, whilst being ultimately unsuitable for U-metal storage without further development around the reduction of water availability.

A numerical model of two-phase plume developments in a small scale turbulent ocean is proposed and designed as a fundamental study to predict the near field physicochemical impacts and biological risk to the marine ecosystem from CO2 leakage from potential carbon storage locations around the North Sea. New sub-models are developed for bubble formation and drag coefficients using in-situ measurements from videos of the Quantifying and monitoring potential ecosystem Impacts of geological Carbon Storage (QICS) experiment. Existing sub-models such as Sherwood numbers and plume interactions are also compared, verified and implemented into the new model. Observational data collected from the North Sea provides the ability to develop and verify a large eddy simulation turbulence model, limited to situations where the non-slip boundary wall may be neglected. The model is then tested to assimilate the QICS experiment, before being applied to potential leakage scenarios around the North Sea with key marine impacts from pCO2 and pH changes. The most serious leak is from a well blowout, with maximum pH changes of up to -2.7 and changes greater than -0.1 affecting areas up to 0.23 km2. Other scenarios through geological structures would be challenging to detect with pH changes below -0.27.

Polybrominated diphenyl ethers (PBDEs) have been used for decades as flame retardants in polymeric materials. Products containing lower brominated congeners have been banned because of concerns about their toxicity to neurological, reproductive and endocrinal systems. Restrictions on the use of the deca-BDE mixture, which contains 97% of the fully brominated congener BDE-209, have been initially delayed. Nowadays the addition of BDE-209 to the Stockholm Convention on Persistent Organic Pollutants is under evaluation. BDE-209 fate in soil, as for other hydrophobic organic compounds, is strongly related to soil organic fraction. This thesis investigates BDE-209 sorption kinetics and identifies other factors important for evaluating BDE-209 mobility, degradation and bioavailability in soil. Additionally it moves the first steps in the development of a novel bioaugmentation technique through fungi. For this purpose, HPLC analytical methods and extraction techniques commonly used for hydrophobic organic compounds (HOC) have been tested for analysis of BDE-209 in water and soil samples. The best recoveries values were obtained by evaporation and substitution of water (WES) and by pressurised liquid extraction (PLE) of soil. Regarding BDE-209 sorption in soil, the sorption kinetic profiles for two soil matrixes belonging to the mineral domain (kaolin) and organic matter domain (peat) were studied separately. Sorption on kaolin was much faster than in peat (4 hours compared to more than 10 days). This approach made it possible to identify other important factors influencing BDE-209 sorption and partitioning processes: clay minerals and dissolvable organic matter. In relation to the biodegradation aspect, this thesis investigated the tolerance of P.ostreatus (a specie of white rot fungus with documented mycoremediation ability) to BDE-209. The fungus mycelium in co-existence with a soil bacterium demonstrated the ability to colonised straw contaminated with BDE-209 up to 1 mg/kg. The results encourage further investigation on P. ostreatus ability to degrade BDE-209.