Nowadays, the quality of air in the indoor environment is of increasing concern as it is estimated that the majority of people in developed countries spend about 85% of their time in various indoor micro-environments. The biological fraction of airborne particulate matter has become of increasing interest owing to the potential allergenic and pathogenic nature of airborne micro-organisms. Biological aerosols are ubiquitous and abundant in the air we breathe in the built environment and despite the recognition of the importance of bioaerosol exposure on human health, relatively little is known about the microbial agents in indoor air and there are still critical gaps in our understanding of the airborne microbial communities. Molecular biology methods demonstrate a great potential for improving our comprehension of the significance of the indoor aerosol microbial load in the context of human exposure, providing in-depth characterisation of microbial communities. However, the number of bioaerosol studies which have applied culture-independent techniques is still limited and the data on the airborne microbial particles in indoor environments remain scant and need to be further examined. The aim of the present study is to investigate the microbial abundance and diversity of bioaerosols in various different types of indoor environments using molecular techniques. Several research questions are being addressed by application of high throughput next generation sequencing technology, providing insights into the aerosol microbiome in micro-environments where people spend considerable amount of their time on a daily basis, including educational, residential and transportation settings. The results of this project provide novel information on a previously largely unexplored microbiome which could improve and expand our comprehension of the specific characteristics of bioaerosols in the indoor environment. Moreover, the data generated by this study could make a significant contribution to improving air quality by facilitating the development of methods for bioaerosol exposure monitoring.

Electrocoagulation (EC) is an effective water and wastewater treatment technology; where the coagulants are generated in-situ by electrolytic oxidation of a sacrificial anode. In this technique, pollutant removal is done without adding chemicals; therefore, it remarkably reduces the sludge produced, and consequently reduces the cost of sludge handling. This method has been efficiently used to remove, up to 99%, of a wide range of pollutants such as heavy metals, oil, dyes, and fluoride. However, the EC technology still has a deficiency in the variety of reactor design, and its performance is highly influenced by the chemistry of the water being treated, especially the presence of organic matter (OM), as this inhibits heavy metal removal due to the formation OM-heavy metals complexes. The presence of heavy metals and OM in water resources is one of the most problematic pollutants in Hilla River, Babylon city, Iraq, which inhibits the application of the EC method in that area. Thus, the current study has been devoted to develop a new hybrid EC rector that can be applied to treat water drawn from Hilla River especially, and to treat water containing OM-heavy metals complexes. The aims of this study are therefore; firstly to examine the removal of heavy metals from drinking water in the presence of OM-heavy metal complexes using a new hybrid treatment method that utilises a combination of microwave-electrocoagulation (MW assisted-EC method). Secondly, to present a new configuration for an electrocoagulation reactor (FCER) that employs perforated plate flow columns (which are widely used in the chemical industry) to achieve water mixing, aeration, and temperature control processes. Additionally, the development of statistical models for the EC performance, recovery of hydrogen gas, and the removal of biological pollutants are other targets in the present project. Initially, the performance of the new flow column EC reactor (FCER) was validated in terms of water mixing efficiency, water aeration, and temperature controllability. The results were compared to those of traditional EC reactors. Then, the ability of the FCER to work as an EC unit was validated by treating different pollutants such as fluoride, nitrate, iron, and reactive black 5 (RB-5) dye from drinking water. Then, the ability of the new MW assisted-EC method to remove OM-heavy metal complexes was experimentally proved by treating synthetic water samples contain iron (Fe2+) ions and ethylenediaminetetraacetic acid (EDTA) (C10H16N2O8) (as organic matter). The results obtained showed that FCER achieved a complete water mixing efficiency, and increased the dissolved oxygen (DO) concentration by 110.6% within 10 min, and kept the temperature of water being treated within the range of 22-28 oC for 30 min of electrolysing. While the traditional reactors achieved water-mixing efficiency of 96.5%, increased the DO by 52.2%, and the temperature increased to about 32 oC over the same treatment period. Additionally, FCER was able to reduce fluoride, iron, nitrate, and RB-5 dye concentrations by 98%, 99.6%, 95.2%, 98.6%, respectively. In terms of OM-heavy metal complex removal (the novelty of the present work), the results obtained demonstrated that this novel method removes 92% of this refractory complex within 35 min of treatment at a power of 100 W, temperature of 100 oC, initial pH of 6, ID of 5 mm, and CD of 1.5 mA/cm2. While, the traditional treatment (EC only) removed only 69.6% of this complex under the same operating conditions. It is noteworthy to mention, the new MW assisted-EC method achieved 100% removal of culture-able activated sludge microorganisms ASM from drinking water, which could eliminate the need for costly separated biological treatment units. Statistically, empirical models were developed to reproduce the performance of FCER in terms of fluoride, nitrate, RB-5 dye, iron, and iron-EDTA complex removal. The R2 value for the models of fluoride, nitrate, RB-5 dye, iron, and iron-EDTA complex removal were, respectively, 0.823, 0.848, 0.798, 0.868, and 0.923. Economically, it has been found that the preliminary operating cost of the MW assisted-EC method is 0.628 US $/m3. Additionally, it has been found that the generated hydrogen gas from this new method could be used to reproduce about 2.82 kW/m3 of power, which is a promising amount of power on field scale plants. In conclusion, according to the obtained results, the new MW assisted-EC method is a safe promising alternative to the complicated, expensive, and time consuming traditional treatment methods, as it removes heavy metals in the presence of OM in a relatively short time without the need for chemical additives. Economically, the MW assisted-EC method reduces the need for separated biological treatment unit that require space, money, equipment, and time, because drinking water will be sterilised as it passes through the microwave field. The latter merit makes this new method a cost-effective alternative. Additionally, FCER reduces the need for external mixing and aeration devices that require extra power to work, which makes FCER a cost-effective alternative for traditional lab-scale EC units.

During the past decade, there has been a considerable increase in the number of published works on multiphase machines and drives. This increased interest has been largely driven by a need for the so-called green energy, i.e. energy generated from renewable sources such as wind, and also an increased emphasis on greener means for transportation. Some of the advantages multiphase machines offer over three-phase counterparts are better fault tolerance, smaller current and power per phase, and higher frequency torque ripple. This thesis examines use of a multiphase induction generator in wind energy conversion systems (WECS). In particular, multiphase generators that comprise multiple 3-phase winding sets, where each winding set is supplied using an independent 3-phase voltage source inverter (VSI), are studied. It is claimed that these topologies offer advantages in cases where a WECS is connected to a multitude of independent ac or dc microgrids, systems where a single high-voltage dc link is needed or where a simple fault tolerance is achieved when a complete winding set is switched off. All of these examples require an arbitrary power or current sharing between winding sets. In order to achieve arbitrary current and power sharing, the control can be implemented using multi stator (MS) variables, so that the flux and torque producing currents of each winding set can be arbitrarily set. As an alternative, this thesis uses vector space decomposition (VSD) to implement the control, while individual winding set flux/torque producing currents are governed by finding the relationships between MS and VSD variables. This approach has all the advantages of both MS and VSD, i.e. access to individual winding set variables of MS and the ability to implement control in the multiple decoupled two dimensional subspaces of VSD, while heavy cross coupling between winding set variables, a weakness of MS, is avoided. Since the goal of the thesis is to present use of multiphase machines in WECS, modelling and simulation of a simple multiphase WECS in back-to-back configuration has been performed at first. All systems relevant to machine control where considered, such as grid and machine side VSIs, grid filter, indirect rotor field oriented control, current control in both flux/torque producing and non-producing subspaces, low order harmonic elimination, maximum power point tracking control, and voltage oriented control of the grid side VSI. Moreover, various WECS supply topologies were considered where developed current and power sharing would be a necessary requirement. Development of the proposed current sharing control commences with an analysis of multiple 3-phase machine modelling in terms of both MS and VSD variables. Since the actual control is implemented using decoupled VSD variables, VSD modelling has been studied in detail, resulting in an algorithm for creation of the VSD matrix applicable to any symmetrical or asymmetrical multiphase machine with single or multiple neutral points. Developed algorithm always decouples the machine into orthogonal two-dimensional subspaces and zero sequence components while making sure that all odd-order harmonics are uniquely mapped. Harmonic mapping analysis is offered as well. Next, relationship between MS and VSD variables has been developed by mapping MS variables into VSD subspaces. Since VSD matrix creation algorithm is valid for any multiphase machine, relationship between MS and VSD variables is applicable to any multiple 3-phase machine regardless of the configuration (symmetrical/asymmetrical), number of neutral points or machine type (synchronous or induction). Established relationship between MS and VSD has been used to implement current sharing control in decoupled VSD subspaces of the machine. It is shown that in order to achieve arbitrary current sharing it is only necessary to impose currents in flux/torque non-producing subspaces. Hence, total machine’s flux and torque are not affected at all. Besides verification by Matlab simulations, two topologies are experimentally investigated, a parallel machine side converter configuration and the case when a single high voltage dc link is created by cascading dc-links of the machine side VSIs. In the first case the ability of arbitrary current sharing between winding sets is validated, while the second tested topology demonstrates use of the developed control for the purpose of voltage balancing of the cascaded dc links.

Made available in DSpace on 2015-04-22T22:01:55Z (GMT). No. of bitstreams: 1 Victor Freitas.pdf: 3096771 bytes, checksum: 9102adbcaf7f7b431124f85eda0a0766 (MD5) Previous issue date: 2013-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O desenvolvimento de novos produtos químicos tem melhorado significativamente a qualidade de vida da população. Entretanto esses novos produtos podem ser danosos ao meio ambiente necessitando de meios para sua eliminação ou neutralização. As zeólitas são aluminossilicatos cristalinos que podem atuar como os catalisadores de oxidação/redução (redox) necessários para a formação dos radicais hidroxilas empregadas nos Processos de Oxidação Avançada (POA s), especialmente se algum metal for inserido em sua estrutura cristalina Neste contexto, os POA s têm atraído grande interesse tanto da comunidade científica como industrial por promover a completa mineralização dos contaminantes orgânicos em meio aquoso. Também é apreciável que esses materiais tenho baixo custo para aplicação em grande escala. Dentre os materiais precursores de zeólitas a caulinita apresenta grande potêncial por ser um argilomineral com proporção Si/Al ~ 1 e ter ampla ocorrência natural em todo o território brasileiro. Nesse sentido o presente projeto visa a síntese de zeólita tipo A dopada com ferro, a partir de caulinita amazônica para aplicação em POA s. Foram coletadas duas amostras minerais ricos em caulinita. As amostras foram tratadas química e termicamente antes da síntese zeolítica. Os materiais coletados foram degomados manualmente, passados em peneira de 0,05 mm de malha e seco ao ar. Em seguida os materiais foram misturados a uma solução ácida de HCl 50 % (v/v) na proporção de 1/4 (m/v) por 4 horas. Os produtos foram lavados e filtrados até pH 7. Após o tratamento ácido, os materiais foram aquecidos até 700 oC por 4 horas em forno mufla. A conversão da caulinita em zeólita foi conduzida por três diferentes metodologias e dopada 3 e 5 % (mol/mol) de ferro em relação ao alumínio. A análise química revelou uma razão SiO2/Al2O3 de 2,32 e 1,41 para as amostras A1P e A2P, respectivamente. Também foi verificado um teor de ferro de 7,33 % para A1P e 1,06 % para A2P, esse resultado sugere a presença de outras fases minerais nos materiais coletados. A análise por DRX diagnosticou o argilomineral caulinita como mineral principal e a presença de hematita, quartzo e traços de goethita. Os processos de síntese levaram a formação de cinco fases zeolíticas (FAU, LTA, SOD, CAN e GIS). A fase LTA foi obtida como produto majoritário após a realização da etapa de fusão alcalina (proporção 5/6 (m/m) de matéria-prima/NaOH) seguida de fusão hidrotérmica. A adição de Fe(NO2)3 como fonte de Fe3+ provocou grande perturbação no meio reacional levando a formação majoritária da zeólita cancrinita. Formou-se grande quantidade de óxido de ferro precipitado e misturado a fase zeolítica. Ao final das caracterizações o produto se mostrou um compósito de óxido de ferro nanoestruturado finamente disperso em zeólita. A atividade catalítica dos produtos sintéticos sem dopagem e dopados com 3 % e 5 % frente a degradação do corante orgânico azul de metileno foi avaliada através dos processos Fenton heterogêneo, Fotocátalise e Foto-Fenton heterogêneo. Foi visto que o produto com 5 % de ferro apresentou melhor desempenho em todos os processos, atingindo a remoção de 99 % do corante a 40 ppm em 60 minutos de reação no processo foto-Fenton heterogêneo. O produto com 3 % de ferro apresentou desempenho superior ao do material sem dopagem.

Currently the extraction of valuable components from oils is of growing interest. Palm fatty acid distillate is a by-product from palm oil refining process which contains valuable minor components. The scope of the present work was to investigate the enrichment of high value low concentration components of palm fatty acid distillate namely squalene (1.8-2.3 wt.% squalene) using supercritical carbon dioxide as solvent with counter-current packed column kept under isothermal and longitudinal thermal gradient. The overall objective of this work was to explore the effect of extraction process parameters such as pressure, temperature, and solvent to feed ratio to optimize the conditions that lead to high separation efficiency. This work has been centred on the study of the solubility of the main lipid components in supercritical carbon dioxide, isothermal counter-current extraction, longitudinal thermal gradient fractionation and the effect of feed concentration. Solubility studies have been conducted for binary, ternary and quaternary systems as function of state of conditions through the application of a dynamic method. Binary systems of CO2/squalene, CO2/oleic acid, CO2/\( \alpha \)-tocopherol, and CO2/pseudo-component palm olein were measured at temperatures of 313, 333 and 353 K, and at a pressure range of 10 to 30 MPa. A ternary system of CO2/squalene/palm olein and a quaternary system of CO2/squalene/ palm olein/ oleic acid were also investigated at 313 K and pressures of 10 to 25 MPa. Comparison of the ternary system with the binary system showed a decrease in the solubility of squalene, with a corresponding rise in the solubility of palm olein. In the quaternary system, the presence of oleic acid decreased the selectivity of squalene. Extraction of squalene has been carried out on a counter-current glass beads packed column with the dimensions of 11.45 mm internal diameter and 1.5 m of effective height. The pressure and temperature were the operating conditions investigated and they varied from 10 – 20 MPa and 313 – 353K, respectively. Experimentation has demonstrated that squalene high fraction is achievable, however, squalene recovery has been found to be highly dependent on the extraction pressure and temperature. Squalene and free fatty acids content in the extract increased, and triglycerides content decreased during most of the fractionation runs. Longitudinal thermal gradient profiles along the column were investigated for further recovery of squalene, results showed the highest squalene recovery of more than 95% was reached and concentration of squalene was increased from 2wt% in the feed to 16wt% in the top product.

Biogas is not ideal for combustion in diesel engines mainly due to its low energy content. The upgrading of biogas into high quality syngas through catalytic reforming reactions was investigated. Studies on the effect of temperature, space velocity and O\(_2\)/CH\(_4\) molar ratio on various basic biogas reforming processes were done. The dry reforming of biogas was found to be active at high reactor temperatures with syngas production and reduction of carbon dioxide. The promotion of simultaneous dry and oxidative reforming by adding oxygen improves syngas production at conditions of low temperature and high space velocity. Subsequently, the biogas exhaust fuel reforming process was done by feeding real engine exhaust together with biogas into the reforming reactor. Reforming process efficiency of 95% (ratio of energy content of reformate to biogas) was achieved at high space velocity and high content of steam in exhaust at medium engine load (300°C exhaust temperature). Further improvement was observed when reformed exhaust gas recirculation (REGR) was applied due to increased exhaust steam content in the engine – reactor system which promoted the endothermic steam reforming reaction. Moreover, improved engine thermal efficiency and lower emissions were found during reformate gas-diesel operation compared to biogas-diesel operation.

An innovative approach to translating probabilistic UKCP09 weather generator information into a usable and replicable risk-based climate change impacts assessment and a basis for robust adaptation planning in the England and Wales water sector is described. Applying metrics of risk in the form of crossing control curves at a reservoir, quantitative assessments of the extent to which a Water Resource Zone (WRZ) can be considered robust to climate change-induced water shortages given the application of adaptations options are made. It is shown in a case study of the North Staffordshire WRZ that in its current set-up, the system cannot be deemed robust to climate change from the 2030s onwards. Applying demand and supply-side adaptation options to the WRZ increases the robustness of the system to varying extents. The approach used shows that it is possible to make decisions on how the WRZ can be made robust to future conditions by identifying key metrics of risk, and applying an acceptable probability of not satisfying that risk in the future. Furthermore, a novel analysis of two sources of uncertainty involved in climate change assessments is produced in terms of water shortage probability for the first time, and two downscaling techniques are assessed.

The shortage in water resources have been observed all over the world. However, the safety of drinking water has been given much attention by scientists because the disinfection will react with organic matters in drinking water to generate disinfection by-products (DBPs) which are considered as the cancerigenic matters. Although much research has been carried out on the water quality control problem in DWDS, the water quality model considered is linear with only chlorine dynamics. Compared to the linear water quality model, the nonlinear water quality model considers the interaction between chlorine and DBPs dynamics. The thesis proposes a nonlinear model predictive controller which utilises the newly derived nonlinear water quality model as a control alternative for controlling water quality. EPANET and EPANET-MSN are simulators utilised for modelling in the developed nonlinear MPC controller. Uncertainty is not considered in these simulators. This thesis proposes the bounded PPM in a form of multi-input multi-output to robustly bound parameters of chlorine and DBPs jointly and to robustly predict water quality control outputs for quality control purpose. The methodologies and algorithms developed in this thesis are verified by applying extended case studies to the example DWDS. The simulation results are presented and critically analysed.

This research focused on evaluating the water savings that could be achieved from Trade Effluent Recycling and Reuse (TERR) in the UK Food and Beverage Manufacturing Sector (FBM) and on identifying the current and future factors that can impact on the success of this application in the UK. The research data suggest that the water regenerated from a widespread application of TERR in the FBM can potentially satisfy 44% of future increases in water demand. However, it was evident from the research findings that there is a need to clarify implementation strategies and validate the safety, reliability and economic feasibility of TERR projects before this application can be approved by the salient stakeholders in the FBM. Alternative future scenarios were also developed to evaluate the impact that changes in the environmental and socio-economic domains (ESE) are likely to have on TERR in the FBM. It was evident from the narratives that emerged from these scenarios that future changes in ESE are likely to have a positive impact on the approval of TERR projects. The findings also highlight the key role that TERR can potentially play in improving the resilience of the UK against future water shortages through providing a significant percentage of the projected future increases in water demand.

This thesis aims to apply recent conceptual frameworks for climate change impact assessment to the road freight sector of Great Britain in order to identify potential future safety issues. The freight sector is a key component of Great Britain’s economy, and one which is particularly vulnerable to the effects of adverse weather. An assessment of the current patterns in weather related freight accidents is produced, and existing studies on accident causation are elaborated upon to arrive at relationships between key meteorological parameters and freight accident rates. These relationships are extrapolated onto various climate scenarios under low, medium and high emissions for the 2020s, 2050s and 2080s using UKICP09 climate tools to arrive at projections of possible impacts at a regional scale. This thesis also addresses a key criticism of the previous climate change impact assessment literature; that studies usually neglect the consideration of what the network will look like in the future, how it will be used, and how this will impact upon its vulnerability to meteorology. The way in which the network is designed, the resilience of the vehicles that operate on it and the split of usage between the various modes will all affect the impacts that are likely to be seen, and are all determined by the broader socio-economic pathway of the country. Delphi techniques are used for short term forecasts of growth and to identify emerging issues with the industry. UKCIP data is used to extend these projections to 2050. By combining social and physical techniques, a more holistic picture of future impacts is found. Although the confluence of safer technology and a reduction of winter road icing and summer precipitation events could potentially lead to a safer operating environment, certain scenarios which promote high emissions, a larger freight fleet and low investment in infrastructure could cause problems, especially for winter precipitation events.