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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.

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If the UK is to address its energy reduction targets, it is vital to understand energy use behaviours and to devise technology that positively encourages domestic occupants to use less energy. This study is cross-over research that spans energy research, social science and socio-technology. The work presented in this dissertation reveals the domestic energy saving potential of the use of In-hone Displays (IHDs) by quantifying changes in actual energy consumption and then evaluating these changes using social science research techniques to document the psychological nature of the human interaction with a digital user interface (UI). Many studies have investigated how IHDs for domestic electricity use change behaviour; the findings of this unique 37 month pre-normative study, the first of its kind in the UK, show that the coloured dual-fuel IHD had a positive effect on consumption behaviour and energy reduction. However, the exact difference in energy consumption between experimental groups is dependent on the type of normalisation condition applied to the recorded energy consumption. After the first six months of monitoring, those with a coloured IHD reduced their gas consumption by an average of 20% compared to a control group; this was tested to be statistically significant (p < .05). This difference in consumption was similar for those living in flats and those living in houses. The quantitative figures are reinforced by the findings from questionnaire and the semi-structured interviews, which show that those with an IHD were significantly more likely to reduce their gas consumption and reported increased use of the controls and settings like thermostats for heat-related appliances. Thirty-one months later, this change in gas use behaviour persisted. Over the total 37 month monitoring period, the majority of participants continued to engage with the IHD on a daily basis and consumed 27% less gas than the control group. This difference reached statistical significance (p=.05). The questionnaires conducted 31 months after the initial findings found that those in the intervention group had statistically higher gas reducing behaviour change scores (p < .05). The first six months of energy data show that the sample group with the IHD used 7% less electricity than the control group. The difference in group means was found to not be statistically significant (p > .05). The difference in electricity consumption was considerably higher in the sample living in houses than in the sample living in flats. Qualitative feedback from the participants suggests that the use of the IHD had a slight positive effect on users' consciousness of reducing electricity consumption. However, a larger portion of the occupants with no IHD were similarly confident in ingrained methods of regulating and reducing their electricity consumption. Thirty-one months later, the difference in electricity consumption was substantially higher than was measured for the first six months. Over the total 37 month monitoring period, the intervention group consumed 21% less electricity than the control group. This was not statistically significant (p > .05), the interviews found that those with an IHD did not directly attribute their reduced use of electricity to the IHD. Rather, they maintained low levels of electricity use because it was an ingrained habit long before they used the IHD and for fire and safety reasons. Between the 6 month report and 31 month report, both experimental groups reduced the amount of electricity and gas they consumed. This was attributed to changes in weather patterns and occupants growing more accustomed to their new home. The properties with highest gas consumption reduced their consumption closer to that predicted by the Standard Assessment Procedure (SAP). The research found contrasting differences in how the two utilities where perceived and used. This was evident when the energy data was divided into groups based on occupancy. Larger savings in gas consumption was seen in the intervention group with lower occupancy: the intervention group consumed considerable more electricity than the control group in the lower occupancy dwellings, and consumed considerably less in the larger occupancy dwellings. Electricity was described as a luxury, used to maintain a certain quality of life. Those with younger dependents felt it necessary to provide them with as much electronic luxury as they could. Electricity was relatively freely accessed and used by all residents with little resistance if a justified reason was given for its use. However, space heating was perceived as a sacrificial commodity. Heat was described as being relatively easy to regulate with the use of blankets and extra clothing. Heating controls were perceived to be out of reach for many but one or two in the household. This tended to be in control of the person responsible for the majority of household tasks. The users of Ewgeco IHD commented more on the device's ability to promote new gas saving behaviour in order to reduce gas consumption. In contrast, the visual representation of real-time electricity consumption was used more as a safety feature, and appears to fail to produce significant electricity reduction. The participants used the electricity consumption information to reinforce their existing levels of electricity use awareness and it highlighted electrical appliances that had been left on to them. This was reported to be specifically useful at times when the occupants were retiring from the living spaces in the home. These findings demonstrate that a simple ‘push-information' style IHD may need to evolve further with greater smart home control functionality, internet capability and user interaction for this technology to be part of the low-carbon solution. However, it has also been demonstrated that, for particular household groups, IHDs can lead to longer term changes in energy consumption behaviour, specifically for heat.

In the wood fuel supply chain, the water contained in the product determines one aspect of the quality of the wood. It is necessary to reduce the moisture content (MC) of the wood in order to reduce transport and storing costs and also to increase the heating value of the wood. In this thesis a solar thermal application has been developed to dry woodchips using exclusively solar energy. The novel solar woodchip dryer comprises a small woodchip dryer and a solar air thermal system (SATS) to increase the temperature of the drying air. The particularity of this woodchip dryer is that the input air flow is governed by a photovoltaic driven fan. Based on the experimental results obtained, the woodchip dryer and the SATS thermal performance were modelled and a simulation tool for predicting the dried woodchip production during a period of time has been developed. Two small capacity dryers, a thin and a thick layer dryer, have been designed and built to dry woodchip based on the flow capacity of the SATS. The drying performances are studied for both configurations comparing the drying times, drying rates and efficiencies at different test conditions. The drying curves obtained from each test are modelled as a function of key parameters, temperature and velocity employing the Page model equation. Based on the experimental results, a drying model has been successfully developed to predict the MC when the woodchip dryer operates within a range of drying conditions. A quantitative and qualitative analysis of the SATS thermal performance has been conducted employing various solar air collector configurations under Scottish weather conditions. The pneumatic characteristics of the solar dryer including the dryer are determining for the analysis of the system performance. Because of the PV driven fan electrical characteristics, the SATS presents a unique operation regime in which air flow depends exclusively on solar radiation. Thus the SATS thermal performance has been successfully modelled as a function of irradiance. The study necessarily includes the effect of environmental factors such as wind and cloudiness in the transient regime. The potential of using a solar woodchip dryer has been assessed based on the results obtained from modelling the dryer and the SATS together. The feasibility and employability of using the solar dryer for drying woodchips is discussed considering the productivity, the energy savings, costs and integration.

This thesis investigates the application of large scale concentrated solar (CSP) and photovoltaic power plants in Libya. Direct Steam Generation (DSG) offers a cheaper and less risky method of generating electricity using concentrated solar energy than Heat Transfer Fluid (HTF) plant. However, it is argued that the location of a DSG plant can be critical in realising these benefits, and that the South-East part of Libya is ideal in this respect. The models and calculations presented here are the result of an implementation of the 2007 revision of the IAPWS equations in a general application based on Microsoft Excel and VBA. The hypothetical design for 50MW DSG power plant discussed in this thesis is shown to yield an 76% reduction in greenhouse gas emissions compared to an equivalent gas-only plant over the ten-hour daily period of operation. Land requirement is modest at 0.7km2. A new method for improving the distribution of heat within the absorber tube wall was developed. Internal helical fins within the absorber tube have been proposed to provide a regularly pitched and orderly distribution of flow from the ‘hot' to the ‘cold' side of the absorber tube. Note that the irradiance profile on the absorber tube is highly asymmetric. A CFD simulation using FLUENT software was carried out for three types of pipes with different internal helical-fin pitch, and an aluminium pipe without fins. The results show that the thermal gradient between the upper and lower temperature for the pipe without a helical fin is considerably higher compared with the pipes with helical fins. Also, the thermal gradient between the two halves for the aluminium pipe (without a helical fin) is much lower when compared to the result for the traditional steel pipe (without a helical fin). A 50MW PV-grid connected (stationary and tracking) power plant design in Al-Kufra, Libya has been carried out presently. A hetero-junction with intrinsic thin layer (HIT) type PV module has been selected and modelled. The effectiveness of the use of a cooling jacket on the modules has been evaluated. A Microsoft Excel-VBA program has been constructed to compute slope radiation, dew-point, sky temperature, and then cell temperature, maximum power output and module efficiency for this system, with and without water cooling for stationary system and for tracking system without water cooling. The results for energy production show that the total energy output is 114GWh/year without a water cooling system, 119GWh/year with a water cooling system for stationary system and 148GWh/year for tracking system. The average module efficiency with and without a cooling system for the stationary system is 17.2% and 16.6% respectively and 16.2% for the tracking system. The electricity generation capacity factor (CF) and solar capacity factor (SCF) for stationary system were found to be 26% and 62.5% respectively and 34% and 82% for tracking system. The payback time for the proposed LS-PV power plant was found to be 2.75 years for the stationary system and 3.58 years for the tracking system. The modelling that was carried was based on the measurements conducted on the experimental system set in a city in the southern part of Turkey. Those measurements are recorded by a Turkish team at Iskanderun. As well as the current, voltage and cell temperature of the photovoltaic module, the environmental variables such as ambient temperature and solar irradiance were measured. These data were used for validation purposes. The correlation for the conversion of solar irradiation from horizontal to sloped surface indicated that the presently used model is highly successful reflected by the goodness of fit parameters: the coefficient of determination is 0.97, and the mean bias error -2.2W/m2. Similarly, the cell temperature model used in the present thesis is validated by the following correlation parameters R2 = 0.97 oC, while MBE is 0.7 and RMSE = 2.1 oC.

This thesis presents a comprehensive investigation into the underlying coupled processes in coal in response to high pressure gas injection. This is achieved by i) developing a new high pressure gas experimental facility and conducting a series of experimental tests, and ii) developing and applying a theoretical and numerical model. A novel experimental facility was designed, which offers stable and continuous high-pressure injection of gases in fractured rocks, for detailed study of the reactive transport processes. It consists of the gas supply and backpressure control system. Using the newly developed experimental facility, the response of coal subject to subcritical and supercritical gas injection under stable and variable temperature conditions was studied. The experimental investigation consisted of a series of tests: i) sorption capacity and kinetics tests, ii) uniaxial compressive tests, iii) sieve analysis tests, iv) flow and deformation tests. Thirty anthracite coal samples from different depths (i.e. 150 m and 550 m) and locations from the South Wales coalfield were characterised and tested. The capabilities of the theoretical and numerical modelling platform of thermal, hydraulic, chemical and mechanical processes were advanced. A new theoretical approach was adopted which successfully incorporates reactive gas transport coupled with coal deformation. The development of constitutive relationships describing the sorption induced elastic isotropic swelling of coal and changes in permeability was considered in detail. Numerical solutions of the governing flow and deformation equations were achieved by employing the finite element method for spatial discretisation and the finite difference method for temporal discretisation. The new model was verified for its accuracy via a series of benchmark tests and validated using high-resolution experimental data. The results of the experimental study showed that the sorption capacity and kinetics are sample-size dependent, particularly for deeper coal. Higher and faster sorption of CO2 obtained on powdered samples compared to intact samples indicated that sorption processes are governed by fracture interconnectivity and accessibility of pores. Sorption of CO2 was found to significantly reduce the brittleness, uniaxial compressive strength and elastic modulus of anthracite coals. The results of the post-failure sieve analysis showed that CO2 saturated samples disintegrated on smaller particles than non-saturated samples indicating that sorption induced swelling weakens the coal structure by enhancing the existing and inducing new fractures. During CO2 flow through coal under constant stress, samples experienced swelling resulting in initial reduction followed by recovery of measured flow rates. CO2 sorption induced changes were found to be non-reversible. The results of high CO2 flow through coal showed that CO2 reduced the temperature of the system, associated with Joule- Thomson cooling, enhancing the coal swelling and opposite to expected, increasing the flow rates. Overall, the high-resolution data-set obtained is a significant contribution to the scientific community and is able to provide a means of validation for future models. The results of the verification and validation exercises demonstrated the capability of the developed model to simulate coupled processes involved in gas transport in coal. A series of numerical simulations were conducted to investigate the permeability evolution and CO2 breakthrough in coal subject to supercritical CO2 injection using the developed model. Different scenarios were considered, involving a range of values of the elastic modulus and the parameter defining the coal swelling. The results of the advanced numerical simulations showed that the effect of CO2 sorption induced swelling on permeability reduces with a decrease in coal stiffness suggesting that CO2 sorption induced reduction of elastic modulus would have a positive effect on the ability of coal to conduct CO2. In this work, confidence in the feasibility of CO2 storage in anthracite coals was improved by enhancing the knowledge of high pressure gas-coal interactions through both experimental and numerical investigations. Moreover, it is claimed that newly developed model enables predictions of coupled processes involved in carbon sequestration in coal.

This thesis focuses on modelling the degradation of particles in gas-solid fluidised beds. Modelling is performed by using a coupled approach where the gas phase is treated as a continuum and the solid phase is represented by individual discrete particles, using the discrete element method (DEM). This approach makes it possible to access individual particle properties. By implementing new modelling techniques into the DEM framework, the individual particle degradation behaviour can be numerically described with high accuracy. The main interest is to understand more complex gas-solid systems as encountered e.g. in fluidised beds which might contain numerous degrading particles. This work focuses on verifying and validating these sub-models to be able to obtain accurate information for further suggestions in operation and optimisation of dense particulate systems. Particle degradation is studied by means of thermophysical, thermochemical and mechanical aspects. Drying (thermophysical) is an energy intensive process which makes further research inevitable for further optimisation. Large particles during drying develop temperature and species gradients along their radius, affecting the product quality. The DEM has been used to monitor flow, particle and subparticle properties which have been found useful to control, operate and optimise such large particle drying processes. Pyrolytic (thermochemical) conversion of biomass in fluidised beds represents a promising route for the production of biooil. This process has been modelled and studied under consideration of drying, shrinkage, segregation and entrainment. Breakage or mechanical degradation is often encountered in engineering applications and requires a much better process understanding. Therefore, a new discrete fragmentation method (DFM) has been developed to study breakage in dense particle systems such as fluidised beds but also mills or crushers. Much reliable breakage information can be obtained to further optimise such systems.

The majority of investigations on municipal solid waste (MSW) landfills have been undertaken during the post-closure period, and therefore, the changes that occur in the properties of refuse layers placed during the period of infilling are often ignored. The impact of fiirther tipping of refuse loads on the moisture content, hydraulic and geotechnical properties of emplaced refuse lifts, and the daily cover was examined in this study by undertaking field and laboratory tests on the refuse fill at White's Pit landfill, Poole, Dorset. The field tests involved mainly pit tests and cone penetration tests. The porosity and field capacity of the refuse excavated fromthe pits were determined in 210 litre drums. In addition, factors that influence leachate production, which include the moisture stored in the topsoil and the runoff fromthe landfill were measured. The laboratory tests involved the determination of compression, porosity, and hydraulic conductivity of pulverised refuse samples with and without a cover soil, under increasing vertical loading. The data obtained fromthe tests were used in the simulation of moisture in refuse lifts at the site, using the Hydrologic Evaluation of Landfill Performance (HELP) model. The data were also used to formulate characteristic equations used for determining temporal changes in the physical properties of emplaced refuse lifts. The results of the investigation show a reduction in porosity and hydraulic conductivity, and increase in the density of an emplaced refuse layer according to the quantity of further filling of refuse loads. The density of an emplaced refuse is further increased by the ravelling of the daily cover materials, but its permeability decrease as a result. Under an applied vertical load of 6 kPa, the hydraulic conductivity and density of refuse-only samples were 1.4 x 10"^ m/s and 291 kg/m^, while that for refuse with 7.5 % cover soil were 9.4 x lO'^m/s and 353 kg/m^ respectively. The hydraulic conductivity of a refuse lift with a slightly clay/silt sand cover, however, appeared greater than its calculated value (10^ m/s) at low effective stresses. The similarity between the results of refuse tested in experimental cells in present study and Beaven and Powrie's (1995) large-scale compression cell suggests that empirical models can be derived from the data obtained from cell tests to predict the behaviour of refuse with different densities. Furthermore, relatively small cells can be used in preliminary study of the behaviour of refuse if the particle sizes are reduced in proportion to the size of the test cell. Apart from direct infiltration of water during waste placement, the volumetric moisture content and degree of saturation of a refuse lift increase during the fill period due to compression from overlying lifts. The saturation of the refuse fill is further enhanced by channelled water through the macropores in the cover soil system. The simulation technique used in this study may be used in evaluating alternative designs and plans of a MSW landfill. Large-scale testing of refuse with an intermediate cover soil is recommended.

An overview of the production and consumption of Kuwait electrical energy, installed capacity and peak loads is presented in this research. The results show that Kuwait has a serious problem because of insufficient electrical energy installed and load peaking, which is considered unacceptable. The research also identifies and analyses the geographical and temporal variability of solar energy inside Kuwait. The fundamental solar models are modified to estimate and identify daily and hourly global (direct-beam) and total solar radiation (SR) on horizontal surfaces on the basis of the more readily available meteorological data such as latitude angle, longitude angle, clearness index, solar time and corresponding hour angle. The presented results demonstrate that Kuwait has an abundance of solar energy capability in terms of almost cloudless atmosphere for nine months and twelve hours solar time a day throughout the year. The daily global and monthly averaged solar intensity have been computed. This research shows that the knowledge of SR data is essential for design and sizing of the photovoltaic (PV) systems. A specific type of PV module has been modelled and its characteristics such as I-V and P-V curves for each month of the year have been calculated and analysed using MATLAB/Simulink to determine the amount of DC current, voltage and power. These results form the basis of the grid-connected PV system (GCPV) design from array construction to the reliability of electrical supply. A technical sizing procedure based on sizing algorithm using iterative manual approach (SAIMA) for meeting specific amount of GWh output required by a potential PV system sponsor in Kuwait is presented. SAIMA has been implemented to determine the configuration of the PV array, inverter-to-PV array sizing factor and efficiency of the system according to previous PV module and inverter database. A novel methodology for approximating Pareto front multi-criteria cost-efficiency optimization problem for a proposed GCPV system has been constructed using system planning constraints. The proposed algorithm is based on bi-objective weighted-sum (BoWS) method to maximize the system efficiency and minimize the system cost. A main objective function of both GCPV system cost and efficiency has been stated as function of PV output power and inverter rated power. The proposed function is performed with the Sequential Quadratic Programing (SQP). The results presented in this research have been acquired through simulation of the proposed GCPV to a specific section of Alsabyia generation station part of Kuwait national grid with efficient maximum power point tracking (MPPT) algorithm incorporated into a DC-DC boost converter. The simulations were performed using Power Simulation Software (PSIM). The analytical model of the PV module has been combined with a ‘perturb and observe’ (P&O) method so that MPP is achieved with the external temperature and SR also considered. An inverter is used to track the output voltage of the converter and interface the PV array with the grid. The results show that the model not only achieves the MPP function but also improves the output of the inverter by reducing the ripples in the sine waveforms. Moreover, this research involved using the software package ERACS to analyze the impact of penetrating approximately 100 MW of the proposed PV generation to a part of the generation unit at Alsybia electrical station in Kuwait. The one-line diagram of the network was modeled in ERACS and it’s used to conduct power flow and fault studies. Four network locations were chosen as potential sites to connect the PV system. Power flow studies were conducted on the network for every hour that the PV array contributed power to the network and for 35 different network configurations for each daylight hour. Computer programs were created to conduct all of these power flow studies and to help analyze the data. Fault studies were then carried out on the network, with the PV array connected at all of the potential locations. There were a few faults that caused a fault level greater than 40 kA to flow through the 13.8 kV busbars.