No description available.

No description available.

No description available.

No description available.

No description available.

An extensive series of experimental tests were carried out at the Sheffield municipal solid waste incinerator plant (30 MW) from September 1988 to July 1989 to investigate the influence of the design and operating parameters on the performance of the incinerator which burns domestic and commercial wastes (500 ton/day). The following measurements were made around the plant: temperature measurements, pressure measurements, flue gas composition analysis and determination of physical and chemical properties of Sheffield refuse. Several other miscellaneous measurements were also made to monitor the effect of variation of operating parameters on the performance characteristics of the incinerator. A combustion model of Essenhigh type was then employed to model the combustion processes inside the solid refuse bed on top of the travelling grate. In addition a mathematical model of the finite difference type (FLUENT) was used to predict the three dimensional reacting flows (gaseous phase) within the incinerator geometry. Experimental measurements of gas composition, temperature and exit velocity were compared with model predictions. Modelling results were generally in good agreement with measurements. As a result of the test data and the mathematical modelling of the whole process, suggestions for design improvements for the Sheffield municipal solid waste incinerator were made which will substantially increase the efficiency, reduce emissions of pollutants and reduce the maintenance costs at the plant. These are: a) replacing the existing secondary air system with secondary air nozzles and the use of more secondary air (up to 20 % of total air) in order to generate turbulence in the high intensity combustion zone where it is most needed and b) introducing a baffle into the main stream inside the radiation shaft in order to lower the gas temperatures entering the precipitator and to remove the existing recirculation zone in the shaft.

The response of the lux-biosensors to a range of environmental pollutants was determined, as well as the stability of the biosensors to a range of environmental parameters. The biosensors were found sensitive to a range of pollutants at environmentally relevant concentrations. These included the pollutants prevailing at the contaminated site (BTEX and major co-contaminants). Analysing the bioluminescence dose-response curves to different pollutants, it was observed that the shape of the response appeared to be indicative of the nature of the contaminant present. The application of the lux-biosensors in the screening of groundwater and sediment samples from the contaminated site, showed different levels of toxicity which correlated well with chemical analysis. The sample screening produced a toxicity map of the site, facilitating the identification of hot-spot areas that could be further investigated. Samples with high levels of toxicity were serial diluted and dose-response curves determined to increasing concentrations of the toxic sample, in site uncontaminated groundwater. The shape of the dose-response curve was indicative of the nature of the main pollutant present. The toxic effect of a pollutant detected by the biosensors in spiked environmental samples (groundwater from the study site) correlated with the effect of the same pollutant on mineralisation. This allowed subsequent use of biosensor toxicity for predictive assessment of degradation potential in the presence of the pollutant tested, validating the use of the lux bioassay as a management tool for bioremediation. The bioremediation of the major contaminants (BTEX) on site can be constrained by the presence of co-contaminants or adverse environmental conditions that inhibit microbial activity. The determination of these constraints is crucial for the success of the bioremediation technologies. Using biosensor response linked to sample manipulations, it was possible to determine the contribution of broad classes of pollutants to the total toxicity of the samples.

No description available.

Three techniques are investigated in order to assess their applicability for use in landfill design, construction and monitoring. Firstly, an assessment is made of QA procedures during liner construction through the detailed evaluation of two case studies. Construction QA procedures on-site are compared to available guidelines. The research illustrates the requirement for standardised, regulated QA procedures on landfill sites in order to provide a recognised framework for construction control. The Moisture Condition Value Test (MCV) is evaluated for use as a method of monitoring the placement of compacted clay landfill liners. London Clay and Mercia Mudstone, collected from the QA case study sites, are tested in terms of their suitability as engineered clay liners. Although, London Clay is the most acceptable it is this material which exhibits the poorest results in the MCV testing. This is due to seepage from the apparatus at high moisture contents. The research highlights the problems with the interpretation of the protocol for the testing and the differences between the Scottish and English Road Research Laboratory guidelines (Green & Hawkins, 1987). Thirdly, two airborne remote sensing techniques (ATM and CASI) are appraised as methods of monitoring landfill gas, or possibly leachate migration, from two case study landfill sites in South West England. Vegetation stress can be linked to landfill gas migration (Flower et al., 1981) and this stress can be detected as a deviation from normal spectral reflectances in vegetation (Honer et a!., 1983a). Anomalies are identified on-site through remote sensing but they cannot be directly attributed to the landfills. This research emphasises the effects of contamination from other sources. It also requires the use of a simultaneous ground survey to collate data from boreholes with measurements of soil and vegetation types. Essentially, the QA case studies and the remote sensing show potential for future use and suggestions are made in this thesis for further research. The MCV technique provides a method for assessing the controlling parameters of compaction. With further development of aspects outlined in this investigation there is the potential for specified use of these techniques In landfill engineering and monitoring.

Este trabalho teve como objetivo estudar a redução de poeira de aciaria LD, elétrica e ferrita de zinco utilizando duas composições diferentes de gases redutores. Inicialmente foram realizadas as caracterizações das matérias primas. Esta etapa foi executada através de análise química, difração de raios-X, microscopia eletrônica de varredura, análise granulométrica e densidade aparente. Foi feita também a caracterização térmica das poeiras de aciaria elétrica e LD. Na próxima etapa, pelotas foram confeccionadas a partir das matérias primas em estudo. Em seguida, foram realizadas as etapas de redução. Esta etapa foi desenvolvida com o uso de uma mistura redutora com 90% Argônio com 10% hidrogênio e outra simulando gás natural reformado (utilizando-se a primeira composição de gás redutor mais CO, na proporção de 75% de H2 e 25% de CO). Foram utilizadas vazões de 50, 100, 150 e 200mL/minuto de gás redutor para ambos os gases. Com os dados de perda de massas, partiu-se para a investigação cinética. Esta foi desenvolvida através de uma derivação do método conhecido por Stepwise Isothermal Analysis, onde ao invés da taxa de reação controlar o salto entre os patamares de temperatura, este é gerenciado pelo usuário. Os resultados de caracterização mostraram que a poeira de aciaria elétrica é composta por ferro e zinco e a poeira de aciaria LD é composta principalmente por ferro e cálcio. Na PAE, o ferro apresentou-se como magnetita e o zinco como zincita e franklinita. A poeira de aciaria LD apresentou como principais fases a base de ferro a wustita e a magnetita. Com relação à cinética de redução, foi notado que para as pelotas de poeira de aciaria LD, utilizando mistura gasosa, a etapa inicial de redução (550 a 650°C) foi controlada pela etapa de nucleação e a partir de 700°C, para ambos os gases, a reação passou a ser controlada pela difusão. No caso da redução da ferrita de zinco, foi notado que a etapa inicial de redução (entre 550 a 650°C) foi controlada por reação química. Após 700°C, foi concluído que a reação passou a ser controlada por difusão para ambos gases. Por fim, na redução das pelotas de poeira de aciaria elétrica foi observado que no estágio inicial, a redução foi controlada por nucleação. A partir de 700°C foi visto que a reação apresentou um controle misto entre nucleação e difusão. / The aim of this work was study of the reduction of basic oxygen furnace dust (BOFD), electric arc furnace dust (EAFD) and zinc ferrite. To do this, two different reducing gases were used. Initially, the raw materials were characterized by chemical analysis, X-ray, scanning electron microscope, size analysis and bulk density. Furthermore, thermal characterization was also performed in both BOFD and EAFD. The next step, pellets were made using the raw materials. The reduction tests were carried out on the pellets through two different reducing gases. The first gas used was a mixture between argon (90wt.%) and hydrogen (10wt.%). The last one was a gas simulating reformed natural gas. In this case, it was accomplished a mixture between the first gas with CO. Fluxes at 50, 100, 150 and 200mL/minute were used in this study in both reducing gas. The kinetic investigation was executed through loss mass curve obtained from reduction tests. The method used for kinetic analysis is a method derived from Stepwise Isothermal Analysis (SIA) where the isothermals are controlled by user. The results from characterization showed that EAFD is composed mainly of iron and zinc. The iron´s phase found was magnetite while zinc´s phases detected were zincite and franklinite. The BOFD is composed by iron and calcium. It was verified that the main iron´s phases encountered were wustite and magnetite. The kinetic analysis showed that pellets of BOFD reduced by gaseous mixture at 550 to 650°C was controlled by nucleation. After 700°C, in both reducing gases, the reactions were controlled by diffusion. To zinc ferrite, it was checked out that initially (550 to 650°C) the reaction was controlled by phase boundary reaction. After 700°C, it was concluded that reaction of reduction for zinc ferrite switched to diffusion in both reducing gases. Lastly, reduction of BOFDs pellet was noted (550 to 650°C) that the reduction was controlled by nucleation. Further 700°C, it was observed that the reaction showed a mix control between nucleation and diffusion.