Anaerobic digestion is used to stabilise sewage sludge and produce biogas. Whilst the need to mix digesters is well-recognised, the level of mixing required and its effects on biogas production are not clear. Here, the effects of mixing speed in mechanically-mixed lab-scale digesters on biogas production are considered. For the first time, positron emission particle tracking was used to visualise flow patterns in lab-scale digesters at different mixing speeds. Computational fluid dynamics models were then built to identify the turbulence characteristics. Four lab-scale digesters were run for four months at different mixing speeds and key indicators of digester stability and microbiological population were recorded alongside gas production. Increased mixing speed leads to higher levels of turbulence and in these digesters, increasing the mixing speed reduces the stability of the methane generation process and accordingly has a detrimental effect on the gas production. Similarly, the abundance of methanogenic communities was adversely affected by increasing mixing speeds. However, the unmixed digester produced less biogas than the digester mixed at a low speed, due to uncontrolled digestion. As such, for these digesters, minimal mixing represents the ideal scenario. By considering the velocity gradient in the digester as a surrogate for turbulence, a threshold of 6 8 s-1 was identified. Below this threshold, increased mixing was beneficial but increasing mixing above the threshold was detrimental to digester stability and gas production.

Water supplies have been meeting strict experiments all over the world and the tendencies of reducing precipitations and rising temperatures in the arid and semi-arid of the Middle-East region (such as Iran) aggravate this condition during the last few decades. A proper water planning needs productive Integrated Water Resource Management models that can respond these complicated troubles. The aim of this study was to develop a structure for applicable and efficient risk control of water supplies through drought. This management structure combines hydrological, socio-economic and water organization models. The methodology has three factors: 1) the statistical possessions of drought characterisation and drought trend in terms of space-time were examined and thresholds of drought warning are evaluated to assist as drivers for control programmes. 2) A water-planning model was applied to combine water accessibility and demand and examine the reliability of the water system to deliver the water to demand sites during the normal and drought episodes. 3) The model was used to estimates the future impacts of climate alteration, through driving them with simulations from an ensemble of statically downscaled CMIP5 model for the severest scenario in the 21st century. Moreover, some potential management plans that decrease the future hazard of water shortage were evaluated. The methods were tested in a case study in the Zayandeh Rud River basin in Iran. The results indicated the important roles of both meteorological and anthropogenic elements on occurrence of drought and water shortages for past and future time.

This PhD project was set out to improve the performance of silica gel / water adsorption cooling systems using a number of investigation tools. A novel global lumped analytical simulation model has been constructed for a commercialised two-bed silica gel / water 450kW adsorption chiller. It was integrated with a genetic algorithm (GA) optimisation toolbox to determine the optimum operating conditions to obtain the optimum chiller performance. The model was used to investigate the effect of physical and operating on the chiller performance. The model was also used to investigate the effect of various adsorbent bed enhancement techniques that are presented in published literature. An experimental test facility has been designed, constructed and commissioned to study the performance of scaled down adsorbent bed modules. It has been constructed to understand the effect of the operating conditions on adsorbent-bed heat and mass transfer performance. A dynamic vapour sorption (DVS) gravimetric analyser has been used to characterise a new species of adsorbents (MOFs). These adsorbents have strong potential towards water sorption and could replace the currently applied silica gel. MOFs adsorbents have been characterised in terms of adsorption isotherms and kinetics, in addition to its cyclic analysis. It was found that HKUST-1 (copper based MOF) outperforms silica gel with 95.7% increase in the water uptake. Iron based MOF (MIL-100) was found to outperform silica gel for high evaporating temperature application.

This study aims to investigate the physical properties of particles and their implications for source apportionment and health human exposure studies. A wide range of particle number size distribution (PNSD) measurements was conducted in selected environments using state-of-the-art high time resolution instruments. It is found that PNSD varied in different environments, depending on emission sources and atmospheric processes. A mass balance model was used to predict the penetration, infiltration factors, deposition and loss rates of indoor particles. The loss rates of indoor particles, which are mainly subject to deposition, coagulation and evaporation, were found to be a function of particle size and time. Moreover, HTDMA measurements were performed to study the hygroscopic properties of particles in outdoor and indoor environments, and from five major indoor sources. The particles emitted from indoor sources were mostly hydrophobic. An enhanced lung deposition model based on the ICRP and MPPD models was developed to predict the deposition fraction of particles in the human respiratory tract, with consideration of their hygroscopicity. Furthermore, a combination of lung deposition models and the PMF technique was applied to identify which sources are mostly responsible for deposited particles in the different regions of lung.

Due to some environmental problems for using the common cooling system which works based on the compressor air and cooling gas (Freon), researchers have focused on another type of it. One of the newest methods is using electrocaloric materials to make a cooling system. Electrocaloric effect (ECE) is the reverse of the pyroelectricity which means that the ability of the dielectric materials to change their temperature under electric field. Two ferroelectric materials were selected for this project: BCZT (Ba0.85Ca0.15Ti0.9Zr0.1O3) as a normal ferroelectric and BNT – BT (94 mol% Bi0.5Na0.5TiO3 – 6 mol% BaTiO3) as a relaxor ferroelectric. The results for BCZT shows the best properties with a relative density of 96.1%, the grain size of 32μm, d33 of 410 pC/N and kp of 46% for sintered sample at 1450°C. The highest ECE (∆T= 0.97) was achieved for BCZT sintered at 1450°C (∆T= 0.97). The best properties were founded at BNT-BT sintered at 1125°C with a relative density of 97%, the grain size of 3.2μm, d33 of 165 pC/N and kp of 47%. BNT-BT shows high ECE ∆T= -2.91 and -2.1°C for sintered sample at 1125 and 1150°C respectively under 50 kV/cm which due to two step calcination process is higher than previous researchers.

State-of-the-art diesel exhaust gas aftertreatment systems have proved to substantially decrease vehicles’ emissions. However, their effectiveness depends on the temperature of the exhaust gas and catalysts to activate the emissions’ conversion reactions. In this research study, different strategies for thermal management of diesel aftertreatment systems were investigated to reduce vehicles’ emissions. A thermal energy storage (TES) system was developed and implemented for a light-duty diesel aftertreatment system. In this approach, the extra thermal energy of the exhaust gas during engine’s high-load conditions can be stored and reused when required, in order to maintain the emissions’ conversion reactions during a driving cycle. The results indicated that by increasing the thermal conductivity of the thermal energy storage medium and the catalyst’s substrate, the TES system can reduce the vehicle’s cumulative CO and THC emissions by 91.7% and 41.2% respectively. Active heating of the aftertreatment system was studied to provide the catalysts with the required thermal energy, in order to shorten the catalyst’s light-off period and also prevent the catalyst from light-out during a driving cycle. A pulsating electrical catalyst heating strategy and a combined electrical heating and fuel post-injection approach were developed to increase the heating efficiency while minimizing the vehicle’s emissions.

Plastic waste and its low recycling rate make a significant contribution towards the pollution of the environment. Therefore , it is essential that plastic waste is utilised in different applications . One of the applications is its use either as an aggregate or to form aggregate for use in the concrete. New aggregates were developed using plastic waste and by-product or low cost granular materials. These aggregates have a relatively low density and water absorption as compared to conventional aggregates , and were successfully used to produce sustainable or green lightweight concrete. The new aggregates were used to replace the conventional coarse fraction of either nonnal weight or lightweight aggregates at full or partial replacements; where both properties of fresh and hardened concrete were investigated. It was found that the effect of the replacement level of the conventional aggregate with the manufactured recycled plastic aggregates was less prominent on density as compared to the other properties. The hardened concrete showed a reduction in mechanical properties , with an increase in the proportions of manufactured recycled plastic aggregates in the mix . The assessment of durability properties, thermal conductivity and curing temperature was also carried out. The concrete ductility, drying shrinkage, creep strain and thennal conductivity increased as the content of manufactured recycled plastic aggregate increased in the mix. Whilst, the chloride penneability was found to decrease with an increase in the percentage of recycled plastic aggregate. Finally, models were proposed to predict the mechanical and durability properties utilising the results of this study.

Orientador: Luiz Francisco Prata / Banca: Estevam Guilherme Lux Hoppe / Banca: Paulo Sérgio Jorge / Resumo: A partir de 2005, a comissão do Codex Alimentarius deu início a uma nova empreitada no que diz respeito às práticas da inspeção ante e pós-morte, inserindo-as definitivamente nos planos de segurança e inocuidade. Recomenda-se, a adoção de métodos e técnicas de exames ou de análises que possuam enfoque ou características baseados no sistema APPCC (Análise de Perigos e Pontos Críticos de Controle - HACCP), que tem fundamentos científicos e caráter sistemático, permitindo identificar perigos específicos e medidas para seu controle - prevenção, redução ou eliminação, garantindo a inocuidade dos alimentos em margens de risco (Risk Analysis) aceitáveis internacionalmente. Este estudo visou à análise e a discussão das práticas vigentes durante a inspeção pós-morte de bovinos com base no monitoramento das ocorrências sanitárias durante o ano de 2012 e estudo retrospectivo da evolução dessas ocorrências entre os anos 2007 e 2011, com vistas à discussão e possível adequação dessas práticas com base nos requisitos e recomendações do Codex Alimentarius e do sistema de gestão de caráter preventivo definido pelo plano APPCC, focando-as em análises de risco. Nesse período, foram observados 17.981 casos de cisticercose (1,68%), 557 casos de linfadenite do tipo tuberculosa (0,05%), 1315 ocorrências de abscessos hepáticos (0,12%) e 235 casos de pneumonia (0,02%), num total de 1.067.584 animais abatidos. O índice geral para ocorrência de alterações sanitárias no exame pósmorte para o período foi de 1,9%, significando que dois em cada 100 animais abatidos demandam providências que salvaguardem a saúde dos consumidores. Embora pareça pequena, essa ainda é uma cifra muito elevada que impõe a necessidade do aprimoramento dos programas sanitários na exploração animal e sua efetiva adoção e responsabilização com base nas boas práticas de produção / Abstract: Since 2005, the Codex Alimentarius committee began a new journey regarding the ante and post morten inspection practices, including this practice permanently at the security and safety plans. Methods and techniques tests adoption are recommended or analyze that have focus or characteristics based on HACCP program that have scientific fundamentals and systematic character that permit identify the specific hazard and measures for their control - prevention, reduction or elimination, ensuring the food safety in risk analysis international tolerable. This review aimed to analyze and discussion from adopted practices during the bovine post mortem inspection based on the sanitary occurrence monitoring during 2012, and based on retrospective study of these sanitary occurrences from 2007 to 2011, order to discuss and possible adequacy from these practices based on Codex Alimentarius requirements and recommendations. In this period were observed, 17.981 cases of cysticercosis (1,68%), 557 tuberculosis (0,5%), 13315 hepatic abscess (0,12%) and 235 pneumonia. (0,02%) in a total of 1.067.584 slaughtered animals. The general index to the sanitary changes occurrence at the post mortem exam at the period were 1,9%, what mean that each 100 animals slaughtered 2 need procedures to take care about customers heath safety. Although looks like a small quantity, it's a big number that impose the necessity of the sanitary programs upgrading / Mestre

Waste-to-energy (WTE) is the environmentally preferred method of managing post-recycling wastes. In this process, municipal solid waste is combusted under controlled conditions to generate steam and electricity. Waste is by nature heterogeneous and has a substantially high composition of chlorine (0.47-0.72 wt%) as compared to other solid fuels used for power production. During combustion, chlorine is converted to hydrogen chloride and metal chlorides, which can accelerate the high temperature corrosion of boiler surfaces, especially superheater tubes. This corrosion can significantly affect plant efficiency and profitability by causing unplanned shutdowns or preemptively forcing operators to limit steam temperatures. The following work focuses on the role of chlorine compounds on boiler tube corrosion and investigates approaches for minimizing its effects. The corrosion behavior was studied by conducting laboratory furnace tests on alloys of current and future interest to the WTE industry. Test specimens were coupons machined from boiler tubes to a nominal area of 3.2 cm² (0.5 in²). An chemical environment was introduced in an electrical furnace that replicates the fireside of superheater tube. This included a mixed gas stream with O₂, CO₂, H₂O, HCl, SO₂, and N₂, and temperatures ranging between 400-550°C (752-1022°F). For some experiments, a salt layer was applied to the coupons with a loading of 4.0 ±10% mg/ cm² to understand the behavior of the effects of metal chlorides. Following each experiment, the corrosion rate was determined by taking the mass loss as specified in an American Standard Testing Method (ASTM) protocol, G1-09. Additional insights were obtained by characterizing the coupons via scanning electron microscopy (SEM) and elemental dispersive spectroscopy (EDS). Additionally, the corrosion scale and salt layer were characterized via powder X-ray diffraction (XRD). The addition of 800 ppm of hydrogen chloride (HCl) gas to a mixed gas oxidizing environment accelerated the corrosion rate of SA178A (Fe-0.1C) at 500°C (932°F) as determined by the change in the parabolic rate constant over a period of 72 hours, from 0.18 to 1.7 μm²/h (3.0 E-03 to 2.5 E-02 mil²/h). The findings from the EDS and XRD scale analyses were compared to other literature and thermodynamic calculations that showed that effect that HCl accelerates corrosion via an active oxidation mechanism. A parametric study was performed on the effect of hydrogen chloride on three alloys, SA178A, SA 213-T22 (2.5 Cr-1 Mo-Fe) and NSSER-4 (Fe-17Cr-13Ni). Varying the concentration from 400 ppm to 800 ppm at 500°C increased the mean mass loss by 17.5%, as compared to the 60% increase from 0 to 400 ppm. For each alloy, the mass loss increased sharply with temperature between 450, 500, and 500°C, with corresponding apparent activation energies of Ea NSSER- 4 53 kJ/mol, Ea SA213 T22 110 kJ/mol, and Ea SA178A 111 kJ/mol. The lower apparent activation energy for NSSER-4 demonstrates that effect of hydrogen chloride is mitigated with austenitic alloys versus carbon steel or low alloyed steel. In a comparative study between isothermal and temperature gradient tests, it was also shown that the corrosion of SA178A was not impacted by a temperature gradient up to 250 °C. Another important chlorine compound in WTE boilers are metal chlorides, which are readily contained in fly ash and boiler deposits. Using sodium chloride as a surrogate compound, the corrosion behavior under chloride salts was investigated by applying a salt layer (4.0 mg/cm²) on coupon surfaces. Corrosion under the chloride layer was much more severe than below the HCl-containing atmospheres alone. The mass loss for the commercial steels was increased by more than an order of magnitude. Based on SEM and XRD coupon and corrosion product characterization, this behavior was the result of a second active oxidation mechanism in which sodium chloride reacts with and depletes protective oxides such as chromium (II) oxide. The WTE furnace tests with the sodium chloride layer were executed for six different Ni-Cr coatings, including Inconel 625 (Ni-Cr-Mo), SW1600, SW1641 (Ni-Cr-Mo-B-Si) and Colmonoy 88 and SP 99 (Ni-Cr-B-W). The primary corrosion attack observed was pitting located under the original salt layer. Colmonoy 88, showed superior corrosion resistance with mass losses between 0.3-3.1 mg/cm2 between 450-550°C as compared to the Ni-Cr-Mo, and Ni-Cr-B-So coatings which has mass losses between 10-30 mg/cm². The enhanced corrosion performance of Colmonoy 88 and SP 99 was attributed to the alloying addition of tungsten, which had been previously shown in literature to also improve the pitting resistance for Ni-Cr in aqueous environments. The corrosion behavior under metal chlorides was compared with metal sulfates, which are also prominent in WTE fly ash and boiler deposits. The application of sulfate salts on coupon surfaces was shown to semi-protective on WTE boiler tube surfaces up to temperatures of 550°C. The mass loss for carbon steel and Fe-17Cr-13Ni (NSSER-4) below sodium sulfate was an order of magnitude lower than under sodium chloride. These results motivated experiments aimed at sulfating chloride boiler deposits by increases the sulfur/chlorine gas ratio (SO₂/HCl) in WTE fuel gas. The SO₂/HCl ratio was modified between 0.3 to 0.6 and 1.0 respectively. By increasing the SO₂/HCl ratio, the sodium chloride layer applied on the coupon surface was converted from a chloride rich salt to a sulfate rich and was shown to dramatically reduce the corrosion of tube alloys up to 500°C. The impact of sulfating the alloy was most prominent with alloys with high mass loss under the sodium chloride layer. Tests showed a reduction in the corrosion rates of SA213 T22 (37%), Inconel 625 (23%), and NSSER-4 (27%). At 550 °C, there was no trend with respect to increases of the ratio, which suggests that other corrosion reactions are faster than the rate of sulfation. Finally, the annualized cost factor was defined and proposed as a method for replacing current superheater alloys with alternative materials, such as those tested in this thesis. From this discussion it was calculated that the installation of a colmonoy 88 protected superheater can cost approximately 1.4 times the cost of an Inconel 625 cladded replacement, or as much as 4.3 times the cost of a T22 superheater tube and remain a cost effective option.

Dentre as várias técnicas de tratamento e disposição dos resíduos sólidos urbanos a disposição em aterros sanitários é a mais usada, devido ao baixo custo e relativa simplicidade operacional. No entanto, a falta de estudos para áreas adequadas é um dos principais fatores limitantes da aplicação desta técnica. É imprescindível o conhecimento dos atributos do meio-físico para avaliar as suas várias interações com o aterro sanitário. Essas interações e a variedade de atributos, dificultam a seleção do local adequado para a instalação do aterro sanitário. Diante disto, há a necessidade de uma metodologia que considere as interações, juntamente com os atributos, e se mostre eficaz na seleção do melhor local para o aterro. Propões-se aqui uma metodologia que considera 14 atributos do meio físico, referentes ao substrato rochoso, materiais inconsolidados, água e feições de relevo. Em vista da variedade de atributos, múltiplas alternativas possíveis e objetivos muitas vezes conflitantes, a serem considerados, foi aplicada a técnica de tomada de decisão denominada processo hierárquico analítico (PHA). O PHA divide um problema complexo em problemas mais simples na forma de uma hierarquia de decisão e, permitiu a obtenção do índice de adequabilidade (I.A.), que representa o valor numérico da adequabilidade de uma determinada áreas para a instalação de aterros sanitários, além de possibilitar a sua hierarquização em relação às áreas adjacentes. Esta metodologia foi aplicada na região de Araraquara, estado de São Paulo, limitada pelo paralelos 21º45\' e 22º00\' sul e meridianos 48º00\' minutos e 48º15\' minutos oeste Gr. O I.A. possibilitou o zoneamento e a classificação de unidades de combinação em favorável, moderada, severa e restritiva para a implantação de um aterro sanitário. A metodologia mostrou-se eficaz e permitiu comparar os 14 atributos de forma numérica, ao introduzir a ) técnica de tomada de decisão através do processo de hierarquia analítica. Desta forma, apresentou as vantagens de diminuir a subjetividade do processo de seleção e ponderar atributos inter-dependentes, direcionados ao objetivo de selecionar áreas para a implantação de um aterro sanitário. / Among several techniques for disposition and treatment of urban solid waste, sanitary landfill is the most employed, by their low cost and relative operational simplicity. However, the lack of research for suitable areas is one of the main problems to the application of this technique. It is necessary to know the attributes of the environment to assess their numerous interactions with the environment sanitary landfill. This interactions and the variety of the attributes becomes diffilcut the selection of the most suitable area to the installation of the sanitary landfill. A methodology to be effiecient in the selection of the best site to this facility, must consider the interactions and the attributes of the environment. This paper proposes a methodology which consider 14 attributes of the environment related to the rocky substrate, unconsolidated materials, water and relief. Because the variety of attributes, multiple possible alternatives and competing objectives to be consider was applied a decision support system (D.S.S.) technical named analytic hierachy process (AHP) which divides a complex problem in simpler ones in the form of a decision hierarchy. The use of AHP reaches the numerical suitability index (SI), of the areas to the installation of a sanitary landfill and becomes possible to hierarchy these areas. This methodology was applied in an area located in the Araraquara region, São Paulo state, limited by the parallels 21º45\' and 22º15\' south and meridians 48º00\' and 48º15\' West gr. The use of the suitability index (SI) permitted the zoning and ranking of the sub-areas and their classification in favorable, moderate, severe and restrictive to the installation of a sanitary landfill. The methodology to compare the 14 attributes in a numerical way by the use of the making decision technique applied to the AHP. By this way had the advantage of less subjectivity of the process of area selection and to weigh inter-dependents attributes, addressed to the objective of to select sites to the sanitary landfill.