Dissertations / Theses on the topic 'Biomass fly ash and bottom ash'

Résumé : Depuis le début du XXe siècle, la production de bétons secs représente une industrie importante pour le développement des infrastructures en bétons compactés au rouleau notamment pour la construction de barrages, de digues, de pavages, et les bétons moulés à sec pour la pré-fabrication de blocs de maçonnerie, de briques, de pierres de pavé, etc. La durabilité de celles-ci peut être améliorée en réduisant leur consommation de ciment Portland et de granulats naturels en utilisant, respectivement, des ajouts cimentaires et des matériaux granulaires alternatifs. D’ailleurs, beaucoup de sous-produits industriels et autres ajouts cimentaires alternatifs ne respectant pas les exigences pour le béton conventionnel ont été utilisés avec succès dans ce type de béton. Les cendres de biomasse sont des sous-produits prometteurs pour les applications de bétons secs. Ces cendres sont obtenues dans une centrale de cogénération de l’industrie des pâtes et papiers suite à la combustion de leurs boues de traitement des eaux usées, de leurs boues de désencrage, et autres résidus de bois. Les cendres volantes de biomasse (CVB) ont une finesse similaire à celle du ciment et elles possèdent aussi un potentiel de réactivité pouzzolanique. Elles peuvent donc remplacer une partie du ciment utilisé dans la formulation de bétons. Les cendres grossières de biomasse (CGB) ont une granulométrie voisine de celle d’un sable fin. Elles peuvent donc être valorisées en remplaçant une partie des granulats naturels utilisés dans les formulations de bétons. Bien que les propriétés physico-chimiques et les interactions cimentaires de celles-ci soient étudiées depuis le début des années 2000, très peu d’applications commerciales ou industrielles ont été développées. Ce projet de recherche vise l’étude et l'optimisation des CVB comme ajout cimentaire alternatif et des CGB comme granulats fins alternatifs dans la production de bétons compactés au rouleau (BCR) et à la paveuse (BCP) pour des applications de pavages industriels et dans la production de bétons moulés à sec (BMS) pour des applications de préfabrication de pierres de pavé. Pour chacune de ces applications, des formulations incorporant un taux de substitution jusqu'à 30% du ciment par des cendres volantes et jusqu’à 100% du sable par des cendres grossières ont été réalisées. Ces travaux d’optimisation ont été effectués avec des bétons à rap-port eau-liant de 0,32, 0,35 et 0,37. Les propriétés à l’état frais (maniabilité et consistance), à l’état durci (résistance à la compression, à la flexion et à la traction), et de durabilités (absorption à l’eau, vides perméables et résistivité électrique) jusqu'à 91 jours ont été mesurées pour tous les mélanges de béton. Le rapport eau-liant, la teneur en pâte et les taux de remplacement optimaux ont également été combinés et optimisés afin de valoriser un maximum de cendres de biomasse, volantes et grossières, dans une seule formulation. Les résultats des mélanges de BCR fabriqués en laboratoire avec 10% et 20% de CVB et combinés à 50% de CGB ont respectivement montré des maniabilités désirées et des résistances à la flexion supérieures aux limites prescrites par les devis techniques pour une utilisation pratique de 23% et 29%. Ces deux mélanges donc ont été sélectionnés pour évaluer leur comportement in situ à l’aide de la construction d'une dalle de stockage de 792 m² par 300 mm d'épaisseur à l'aide de pratiques courantes. Des carottes ont été prélevées dans la dalle à 28 et 308 jours. La résistance à la compression des noyaux à l'âge de 308 jours a atteint 33 et 30 MPa pour les deux mélanges testés, respectivement. Les BMS fabriqués avec 5%, 10%, ou 15% CVB et 25% de CGB peuvent atteindre un indice de compaction de 99% avec un travail de compaction inférieur à celui spécifié par les fabricants de pierre de pavés. L'utilisation des CVB et CGB entraîne une faible diminution de la résistance à la compression, mais présente des valeurs de perméabilité et d’absorption à l’eau très faibles et inférieures aux exigences requises les normes (près de 5%). Ces travaux de recherche présentent un débouché potentiel à la valorisation des cendres volantes et grossières de biomasse issues de l’industrie des pâtes et papiers dans les bétons secs comme ajout cimentaires ou granulats fins. Cette approche peut offrir une contribution significative pour la réduction des émissions de gaz à effet de serre associés à la production de ce type de béton et dans les gestions des matières résiduelles de l’industrie des pâtes et papiers.
Abstract : Since the early twentieth century, the production of dry concrete is an important industry for infrastructure development including the construction of dams, core dikes, and pavements using roller-compacted concrete, and precast masonry blocks, bricks, pavers using dry-cast concrete. The sustainability thereof can be improved by reducing its consumption of Portland cement and natural aggregates using cementitious supplementary cementitious materials and alternative granular materials, respectively. Moreover, many industrial by-products and other mineral additions not meeting the requirements for conventional concrete have been success-fully used in such concrete. The biomass ashes are promising supplementary materials for dry concrete applications. These ashes are produced in a cogeneration plant of the pulp and paper industry following the burn-ing of their wastewater treatment sludge, their de-inking sludge, and other wood residues. The biomass fly ash (BFA) have a similar finesse in the cement and they also have a potential poz-zolanic reactivity. They may therefore replace part of the cement used in concrete formula-tions. The biomass bottom ashes (BBA) have a particle size close to that of a fine sand. They can be use to replace a portion of the natural aggregates. Although the physicochemical proper-ties and interactions with cement have been studied since the early 2000s, very few commer-cial or industrial applications have been developed. This research project aims at studying and optimizing the BFA content as an alternative sup-plementary cementitious materials and the BBA content as an alternative fine aggregates in the production of roller-(RCC) and paver-compacted concrete (PCC) for industrial pavements and dry-cast concrete (DCC) for the manufacture of pavers. Formulations incorporating substitu-tion rates of cement up to 30% by BFA and of the sand up to 100% by BBA were evaluated for each of the mentioned applications. This optimization work was carried out with concrete water-to-binder ratio (w/b) of 0.32, 0.35 and 0.37. The fresh properties (workability and com-pactness), hardened properties (compressive strength, flexural strength and splitting-tensile strength) and transport properties (water absorption, permeable voids and electrical resistivity) up to 91 days were measured for all concrete mixtures. The optimal w/b, paste content and replacement rates were also combined and optimized in order to maximize the biomass fly and bottom ashes content, in a single formulation. The results of concrete mixtures made with 10% and 20% BFA with 50% BBA showed 23% and 29% higher flexural strength than the limits required for practical use of RCC, respective-ly. These two RCC mixtures were selected for the assessment of in situ behaviors through the construction of a storage slab of 792 m² per 300 mm thick using standard practices. Core sam-ples were cut from the slabs at age of 28 and 308 days for follow-up of the concrete behavior with time. The compressive strength of the cores at an age of 308 days reached 33 and 30 MPa for the two tested mixtures, respectively. The DCC mixtures made with 5%, 10%, or 15% BFA and 25% of BBA can reach a compact-ness index of 99% with a compaction work lower than specified by the Standards. The use of the BFA and BBA lead to small decrease of the compressive strength, however they can result in very low permeability and water absorption values lower than required by the specifications (close to 5%). This research presents a potential market for recycling biomass fly and bottom ashes from the pulp and paper industry in dry concrete as alternative supplementary cementitious materials or fine aggregates. This approach can provide a significant contribution to reduce greenhouse gas emissions associated with the production of this type of concrete and with the managements of by-products from the pulp and paper industry.

Des millions de tonnes de déchets sont traités chaque année dans le monde entier. Il existe de grandes disparités dans les techniques de traitement des déchets en fonction du niveau de développement des pays. En France, une start-up angevine nommée Néolithe propose une nouvelle voie de traitement des déchets non dangereux non inertes, la fossilisation. Ce procédé est le suivant : broyage des déchets, mélange avec un liant hydraulique puis extrusion pour en faire des granulats appelés Anthropocite®. Les travaux de cette thèse concernent le traitement des ordures ménagères résiduelles (OMR). Ils comportent trois parties : la préparation d’un modèle représentatif des OMR, la valorisation de cendres en matrices liantes, et la solidification du modèle OMR avec différents liants retenus. La préparation du modèle représentatif des OMR nécessite pour les fractions organiques un séchage et un broyage adapté à la finesse de mouture souhaitée. Pour les déchets plastiques il convient d’utiliser des broyeurs spécifiques. Les cendres de biomasse - cendres volantes et de sous foyer - ont été étudiées : caractérisation et réactivité. Des essais d’activation (NaOH et Na2SiO3) ont porté sur les deux types de cendres avec comme variables : le ratio eau sur liant (E/B) et le ratio activateur sur précurseur (A/P). Un précurseur composé de cendres (P1) et de laitier (P3) a été proposé. Les conditions favorables pour l’obtention de résistances en compression minimales de 25 MPa à 28 jours sont un ratio de E/B de 0,4, un ratio A/P de 0,2 et un ratio P1/P3 de 1,50. Pour l’étude de mélanges avec les moutures d’OMR, les liants retenus ont été les suivants : un laitier activé, un précurseur composé de cendres et de laitier, un liant hydraulique dénommé Ligam et un ciment Portland (CEM I) Les premiers essais sur les mélanges ont permis d’établir les protocoles d’inclusion de fermentescibles d’ordures résiduelles (FOR). Tous les liants accusent des retards de prise et de solidification lors d’inclusion. Il est essentiel d’hydrater les déchets (FOR) lors du mélange avec les liants mais chaque liant présente un optimum d’ajout d’eau aux FOR différent. Il est possible de solidifier le modèle représentatif des OMR avec des liants hydrauliques comme avec des liants activés par des alcalins. Les liants hydrauliques semblent plus robustes quant à la nature des composants que représente l’inclusion du modèle OMR à des mortiers. Ces travaux permettent d’établir une base de données, nécessaire à la poursuite des travaux sur la solidification/stabilisation des OMR
Millions of tonnes of waste are treated every year throughout the world. There are wide disparities in waste treatment techniques, depending on the level of development of individual countries. In France, an Anjou-based start-up called Néolithe is proposing a new way of treating non-hazardous, non-inert waste: fossilisation. The process involves shredding the waste, mixing it with a hydraulic binder and then extruding it to produce aggregates called Anthropocite®. The work in this thesis concerns the treatment of municipal solid waste (MSW). It consists of three parts: the preparation of a model representative of residual household waste, the use of ash as a binder matrix, and the solidification of the residual household waste model with various selected binders. For organic fractions, the preparation of a model representative of household waste requires drying and shredding to suit the fineness of grind required. Specific shredders should be used for plastic waste. The characterisation and reactivity of biomass ash - fly ash and underfired ash - were studied. Activation tests (NaOH and Na2SiO3) were carried out on the two types of ash with the following variables: water to binder ratio (W/B) and activator to precursor ratio (A/P). A precursor composed of ash (P1) and slag (P3) was proposed. Favourable conditions to obtain minimum compressive strengths of 25 MPa at 28 days are a W/B ratio of 0.4, an A/P ratio of 0.2 and a P1/P3 ratio of 1.50. The following binders were selected for the study of mixes with SRM grindings: an activated slag, a precursor composed of ash and slag, a hydraulic binder called Ligam and a Portland cement (CEM I). The initial tests on the mixes enabled protocols for the inclusion of fermentable residual waste (FRW) to be established. All binders show delays in setting and solidification during inclusion. It is essential to hydrate the waste (FRW) when mixing with the binders, but each binder has a different optimum to add water to FRW. It is possible to solidify the model representative of MSW with hydraulic binders as well as with alkali-activated binders. Hydraulic binders appear to be more robust in terms of the nature of the components than the inclusion of the MSW model in mortars. This work makes it possible to establish a database, which is necessary for further work on the solidification/stabilisation of MSW

Doutoramento em Ciência e Engenharia de Materiais
In recent years, pressures on global environment and energy security have led to an increasing demand on renewable energy sources, and diversification of Europe’s energy supply. Among these resources the biomass could exert an important role, since it is considered a renewable and CO2 neutral energy resource once the consumption rate is lower than the growth rate, and can potentially provide energy for heat, power and transports from the same installation. Currently, most of the biomass ash produced in industrial plants is either disposed of in landfill or recycled on agricultural fields or forest, and most times this goes on without any form of control. However, considering that the disposal cost of biomass ashes are raising, and that biomass ash volumes are increasing worldwide, a sustainable ash management has to be established. The main objective of the present study is the effect of biomass fly ashes in cement mortars and concretes in order to be used as a supplementary cementitious material. The wastes analyzed in the study were collected from the fluidized bed boilers and grate boilers available in the thermal power plants and paper pulp plants situated in Portugal. The physical as well as chemical characterisations of the biomass fly ashes were investigated. The cement was replaced by the biomass fly ashes in 10, 20 and 30% (weight %) in order to investigate the fresh properties as well as the hardened properties of biomass fly ash incorporated cement mortar and concrete formulations. Expansion reactions such as alkali silica reaction (ASR), sulphate attack (external and internal) were conducted in order to check the durability of the biomass fly ash incorporated cement mortars and concretes. Alternative applications such as incorporation in lime mortars and alkali activation of the biomass fly ashes were also attempted. The biomass fly ash particles were irregular in shape and fine in nature. The chemical characterization revealed that the biomass fly ashes were similar to a class C fly ash. The mortar results showed a good scope for biomass fly ashes as supplementary cementitious materials in lower dosages (<20%). The poor workability, concerns about the organic content, alkalis, chlorides and sulphates stand as the reasons for preventing the use of biomass fly ash in high content in the cement mortars. The results obtained from the durability tests have shown a clear reduction in expansion for the biomass fly ash mortars/concretes and the binder blend made with biomass fly ash (20%) and metakaolin (10%) inhibited the ASR reaction effectively. The biomass fly ash incorporation in lime mortars did not improve the mortar properties significantly though the carbonation was enhanced in the 15-20% incorporation. The biomass fly ash metakaolin blend worked well in the alkali activated complex binder application also. Portland cement free binders (with 30-40 MPa compressive strength) were obtained on the alkali activation of biomass fly ashes (60-80%) blended with metakaolin (20-40%).
Recentemente, as pressões ao nível da segurança, do ambiente e da energia conduziram a uma procura crescente de fontes de energia renováveis, e à diversificação das fontes de energia da Europa. Entre estes recursos a biomassa pode ter um papel importante, uma vez que é considerada como um recurso renovável e neutra em termos de CO2 pois a taxa do consumo é mais baixa do que a taxa de crescimento e pode potencialmente fornecer energia para calor, eletricidade e transportes a partir da mesma instalação. Atualmente, a maioria da cinza de biomassa produzida em unidades industriais é disposta em aterro ou reciclada na floresta ou na agricultura e, na maioria das vezes, isto sucede sem grande controlo. Contudo, considerando que o custo da eliminação de cinzas de biomassa vem crescendo, e que os volumes da cinza de biomassa estão a aumentar, uma gestão sustentável das cinzas tem de ser implementada. O objetivo principal deste trabalho é o estudo do efeito de cinzas volantes de biomassa em argamassas e betões com base em cimento de modo a serem usadas como um material cimentíceo suplementar. Os resíduos analisados no estudo foram colhidos de caldeiras de leito fluidizado e caldeiras de grelha disponíveis em unidades de produção elétrica e em unidades industriais de produção de pasta e papel em Portugal. As caracterizações físicas e químicas das cinzas volantes de biomassa foram efetuadas. O cimento foi substituído pelas cinzas de biomassa a fim de investigar o efeito nas propriedades no estado fresco bem com nas propriedades no estado endurecido de formulações de argamassa e betão. Reações expansivas tais como a reação alcali-sílica (ASR) e as reações sulfáticas (externas e internas) foram estudadas a fim verificar a durabilidade das argamassas e betões de cimento contendo cinzas volantes de biomassa. As aplicações alternativas tais como a incorporação de cinzas em argamassas de cal e a ativação alcalina foram também estudadas. As partículas da cinza de biomassa eram irregulares na forma e finas. A caracterização química revelou que as cinzas eram similares a uma cinza volante da classe C. Os resultados em argamassas mostraram viabilidade para o uso de cinzas de biomassa como materiais cimentíceos suplementares em teores baixos (<20%). A trabalhabilidade, o conteúdo orgânico, o teor de alcalinos, cloretos e sulfatos são razões para impedir maiores incorporações de cinza de biomassa nas argamassas de cimento. Os resultados dos testes da durabilidade mostraram uma redução na expansão para argamassas e betões contendo cinzas de biomassa especialmente quando se misturou cinzas (20%) com metacaulino (10%). A incorporação da cinza de biomassa em argamassas de cal não melhorou as propriedades significativamente embora a carbonatação fosse maior quando da incorporação de 15 ou 20%. A mistura do metacaulino com a cinza de biomassa funcionou bem na aplicação envolvendo a ativação alcalina. Ligantes sem cimento Portland com resistência à compressão de 30-40 MPa foram obtidas pela ativação alcalina das cinzas de biomassa (60-80%) misturadas com o metacaulino (20-40%).

Cement production which is one of the most energy intensive industries plays a significant role in emitting the greenhouse gases. Blended cement production by supplementary cementitious materials such as fly ash, ground granulated blast furnace slag and natural pozzolan is one of the smart approaches to decrease energy and ecology related concerns about the production. Fly ash has been used as a substance to produce blended cements for years, but bottom ash, its coarser counterpart, has not been utilized due to its lower pozzolanic properties. This thesis study aims to evaluate the laboratory performance of blended cements, which are produced both by fly ash and bottom ash. Fly ash and bottom ash obtained from Seyitö
mer Power Plant were used to produce blended cements in 10, 20, 30 and 40% by mass as clinker replacement materials. One ordinary portland cement and eight blended cements were produced in the laboratory. Portland cement was ground 120 min to have a Blaine value of 3500±
100 cm2/g. This duration was kept constant in the production of bottom ash cements. Fly ash cements were produced by blending of laboratory produced portland cement and fly ash. Then, 2, 7, 28 and 90 day compressive strengths, normal consistencies, soundness and time of settings of cements were determined. It was found that blended fly ash and bottom ash cements gave comparable strength results at 28 day curing age for 10% and 20% replacement. Properties of blended cements were observed to meet the requirements specified by Turkish and American standards.

L'industrie du ciment est l'une des principales sources d'émission de dioxyde de carbone. L'industrie mondiale du ciment contribue à environ 7% des émissions de gaz à effet de serre dans l'atmosphère. Afin d'aborder les effets environnementaux associés à la fabrication de ciment exploitant en permanence les ressources naturelles, il est nécessaire de développer des liants alternatifs pour fabriquer du béton durable. Ainsi, de nombreux sous-produits industriels ont été utilisés pour remplacer partiellement le ciment dans le béton afin de générer plus d'économie et de durabilité. La performance d'un additif de ciment est dans la cinétique d'hydratation et de la synergie entre les additions et de ciment Portland. Dans ce projet, deux sous-produits industriels sont étudiés comme des matériaux cimentaires alternatifs: le résidu de silice amorphe (RSA) et les cendres des boues de désencrage. Le RSA est un sous-produit de la production de magnésium provenant de l'Alliance Magnésium des villes d'Asbestos et Thedford Mines, et les cendres des boues de désencrage est un sous-produit de la combustion des boues de désencrage, l'écorce et les résidus de bois dans le système à lit fluidisé de l'usine de Brompton située près de Sherbrooke, Québec, Canada. Récemment, les cendres des boues de désencrage ont été utilisées comme des matériaux cimentaires alternatifs. L'utilisation de ces cendres comme matériau cimentaire dans la fabrication du béton conduit à réduire la qualité des bétons. Ces problèmes sont causés par des produits d'hydratation perturbateurs des cendres volantes de la biomasse quand ces cendres sont partiellement mélangées avec du ciment dans la fabrication du béton. Le processus de pré-mouillage de la cendre de boue de désencrage avant la fabrication du béton réduit les produits d'hydratation perturbateurs et par conséquent les propriétés mécaniques du béton sont améliorées. Les approches pour étudier la cendre de boue de désencrage dans ce projet sont : 1) caractérisation de cette cendre volante régulière et pré-humidifiée, 2) l'étude de la performance du mortier et du béton incorporant cette cendre volante régulière et pré-humidifiée. Le RSA est un nouveau sous-produit industriel. La haute teneur en silice amorphe en RSA est un excellent potentiel en tant que matériau cimentaire dans le béton. Dans ce projet, l'évaluation des RSA comme matériaux cimentaires alternatifs compose trois étapes. Tout d'abord, la caractérisation par la détermination des propriétés minéralogiques, physiques et chimiques des RSA, ensuite, l'optimisation du taux de remplacement du ciment par le RSA dans le mortier, et enfin l'évaluation du RSA en remplacement partiel du ciment dans différents types de béton dans le système binaire et ternaire. Cette étude a révélé que le béton de haute performance (BHP) incorporant le RSA a montré des propriétés mécaniques et la durabilité, similaire du contrôle. Le RSA a amélioré les propriétés des mécaniques et la durabilité du béton ordinaire (BO). Le béton autoplaçant (BAP) incorporant le RSA est stable, homogène et a montré de bonnes propriétés mécaniques et la durabilité. Le RSA avait une bonne synergie en combinaison de liant ternaire avec d'autres matériaux cimentaires supplémentaires. Cette étude a montré que le RSA peut être utilisé comme nouveaux matériaux cimentaires dans le béton.
Abstract : Cement manufacturing industry is one of the carbon dioxide emitting sources. The global cement industry contributes about 7% of greenhouse gas emission to the earth’s atmosphere. In order to address environmental effects associated with cement manufacturing and constantly depleting natural resources, there is necessity to develop alternative binders to make sustainable concrete. Thus, many industrial by-products have been used to partially substitute cement in order to generate more economic and durable concrete. The performance of a cement additive depends on kinetics hydration and synergy between additions and Portland cement. In this project, two industrial by-products are investigated as alternative supplementary cementitious materials (ASCMs), non-toxic amorphous silica residue (AmSR) and wastepaper sludge ash (WSA). AmSR is by-product of production of magnesium from Alliance Magnesium near of Asbestos and Thetford Mines Cities, and wastepaper sludge ash is by-product of combustion of de-inking sludge, bark and residues of woods in fluidized-bed system from Brompton mill located near Sherbrooke, Quebec, Canada. The AmSR is new industrial by-products. Recently, wastepaper sludge ash has been used as cementitious materials. Utilization of these ashes as cementitious material in concrete manufacturing leads to reduce the mechanical properties of concretes. These problems are caused by disruptive hydration products of biomass fly ash once these ashes partially blended with cement in concrete manufacturing. The pre-wetting process of WSA before concrete manufacturing reduced disruptive hydration products and consequently improved concrete mechanical properties. Approaches for investigation of WSA in this project consist on characterizing regular and pre-wetted WSA, the effect of regular and pre-wetted WSA on performance of mortar and concrete. The high content of amorphous silica in AmSR is excellent potential as cementitious material in concrete. In this project, evaluation of AmSR as cementitious materials consists of three steps. Characterizing and determining physical, chemical and mineralogical properties of AmSR. Then, effect of different rates of replacement of cement by AmSR in mortar. Finally, study of effect of AmSR as partial replacement of cement in different concrete types with binary and ternary binder combinations. This study revealed that high performance concrete (HPC) incorporating AmSR showed similar mechanical properties and durability, compared to control mixture. AmSR improved mechanical properties and durability of ordinary concrete. Self-consolidating (SCC) concrete incorporating AmSR was stable, homogenous and showed good mechanical properties and durability. AmSR had good synergy in ternary binder combination with other supplementary cementitious materials (SCMs). This study showed AmSR can be use as new cementitious materials in concrete.

Stricter greenhouse gas emission limits and renewable energy requirements are expected to further increase the worldwide practices of firing biomass and co-firing biomass with coal, which are both considered more sustainable energy sources than coal-only combustion. Reuse options for the by-products of these processes -biomass ash and co-fired fly ash -remain limited. Therefore, this research examines their use as supplementary cementitious materials (SCMs) in concrete and as precursors for alkali-activated geopolymers. Toward their potential use as an SCM, after characterizing these ashes assessing their compliance with ASTM C618 requirements, their impact on early-age hydration kinetics, rheology, setting time and permeability was assessed. Furthermore, the pozzolanic reactivity and the microstructural and hydrated phase development of the cement-ash samples were analyzed. The results show that a wood biomass ash sample was not satisfactory for use as an SCM. On the other hand, the findings demonstrate that co-fired fly ashes can significantly improve the strength and durability properties of concrete compared to ordinary portland cement, in part due to their pozzolanicity. Thus, it is recommended that the ASTM C618 standard be modified to permit co-fired fly ash sources that meet existing requirements and any additional requirements deemed necessary to ensure their satisfactory performance when used in concrete. Toward their potential use in geopolymers, this study characterized the early-age reaction kinetics and rheological behavior of these materials, showing that their exothermic reactivity, plastic viscosity and yield stress are significantly influenced by the activator solution chemistry and other characteristics of the ash. Two co-fired fly ashes were successfully polymerized, with compressive strengths generally highest for ashes activated with solutions with a molar ratio of SiO₂/(Na₂O + K₂O) = 1. The results show that geopolymerization is a viable beneficial reuse for these emerging by-products. Further characterization of these materials by scanning transmission X-ray microscopy analysis revealed the heterogeneity of the aluminosilicate phase composition of the co-fired fly ash geopolymer gel at the nano- to micro-scale.

Traditionally, coal combustion residuals (CCRs) were disposed of with little engineering consideration. Initially, common practice was to use a wet-scrubbing system to cut down on emissions of fly ash from the combustion facilities, where the ash materials were sluiced to the disposal facility and allowed to sediment out, forming deep deposits of meta-stable ash. As the life of the disposal facility progressed, new phases of the impoundment were constructed, often using the upstream method. One such facility experienced a massive slope stability failure on December 22, 2008 in Kingston, Tennessee, releasing millions of cubic yards of impounded ash material into the Watts Bar reservoir and damaging surrounding property. This failure led to the call for new federal regulations on CCR disposal areas and led coal burning facilities to seek out geotechnical consultants to review and help in the future design of their disposal facilities. CCRs are not a natural soil, nor a material that many geotechnical engineers deal with on a regular basis, so this thesis focuses on compiling engineering characteristics of CCRs determined by different researchers, while also reviewing current engineering practice when dealing with CCR disposal facilities. Since the majority of coal-burning facilities used the sluicing method to dispose of CCRs at one point, many times it is desirable to construct new "dry-disposal" phases above the retired ash impoundments; since in-situ sampling of CCRs is difficult and likely produces highly disturbed samples, a sample reconstitution technique is also presented for use in triaxial testing of surface impounded CCRs.
Master of Science

Cement production produces a significant portion of CO₂ emission caused by human activity. The replacing of cement with alternative binders is one way to reduce the CO₂ emission from cement industry and to save natural resources. In Finland, approximately 500 000 tons of biomass fly ash is created annually. Part of this ash could potentially be utilized as a cement replacement material if current concrete standards are modified to allow the use of biomass fly ash as a raw material of structural grade concrete, but even under current legislation biomass fly ash could be already utilized in low value concrete and mortar products or applications. In this study, the suitability of two biomass fly ash, from bubbling fluidized bed combustion, to partially replace cement in concrete was investigated. Cement was replaced also by milled sand to identify the effects of fine inert material. Replacement levels of 10%, 20% and 40% were used. Research methods included a grinding of materials, the preparation of mortar samples, evaluation of fresh mortar paste, strength measurements, calorimetry, electron microscopy, X-ray powder diffraction analysis and chemical analysis. Results of the study demonstrated, that replacement of cement by biomass fly ashes or milled sand had a clear impact on the properties of fresh and hardened mortar. Both fly ashes involved the hydration of cement instead of acting just as a filler material. The chemical composition and performance of two studied fly ash differed greatly from each other and indicated that at least part of biomass fly ashes could be very potential alternatives to replace significant amounts of cement in concrete. On the other hand, some biomass fly ashes can also cause detrimental expansion when used in concrete
Sementin tuotanto on vastuussa merkittävästä osasta ihmiskunnan aiheuttamista CO₂ päästöistä. Sementin korvaaminen vaihtoehtoisilla sideaineilla on yksi keino pienentää sementtiteollisuuden CO₂ päästöjä sekä säästää luonnonvaroja. Suomessa syntyy vuosittain noin 500 000 tonnia lentotuhkaa biomassan poltosta. Osa tästä lentotuhkasta voitaisiin mahdollisesti hyödyntää sementtiä korvaavana raaka-aineena, mikäli nykyisiä betonistandardeja muutetaan tulevaisuudessa sallimaan myös biomassan poltosta syntyvät lentotuhkat betonin raaka-aineina. Nykyisessäkin tilanteessa biomassan lentotuhkaa voitaisiin hyödyntää matala arvoisissa betonituotteissa ja sovelluksissa. Työssä tutkittiin sementin osittaista korvaamista kahdella leijupoltosta peräisin olevalla biotuhkalla. Sementtiä korvattiin myös jauhetulla hiekalla eri vaikutusmekanismien selvittämiseksi. Tutkimuksessa käytettiin 10, 20 ja 40 % korvausasteita. Tutkimus metodit käsittivät materiaalien jauhamisen, kemiallisen koostumuksen analysoinnin, laastinäytteiden valmistamisen, tuoreen laastin ominaisuuksien arvioimisen, lujuusmittaukset, kalorimetrian, elektronimikroskopian sekä hydrataatiossa syntyneiden faasien määrityksen. Tutkimuksen tulokset osoittivat, että sementin osittainen korvaaminen biomassan lentotuhkalla tai jauhetulla hiekalla vaikuttaa selvästi tuoreen sekä lujittuneen laastin ominaisuuksiin. Molemmat tuhkat vaikuttivat sementin hydrataatioon sen sijaan, että ne olisivat toimineet ainoastaan hienona täyteaineena. Tuhkien kemiallinen koostumus sekä vaikutukset valmistettujen näytekappaleiden ominaisuuksiin poikkesivat toisistaan huomattavasti. Tutkimuksen perusteella ainakin osa biomassa lentotuhkista voisivat korvata huomattavia osia betonissa käytettävästä sementistä. Jotkut lentotuhkista voivat puolestaan aiheuttaa betonin haitallista paisumista mikäli niitä käytetään sementtiä korvaavana ainesosana

AN ABSTRACT OF THE DISSERTATION OF RAJNISH PURI, for the Doctorate of Philosophy Degree in ENGINEERING SCIENCE WITH CONCENTRATION IN CIVIL AND ENVIRONMENTAL ENGINEERING, presented on APRIL 15, 2015 at Southern Illinois University Carbondale TITLE: DEVELOPMENT OF HIGH PERFORMANCE CONCRETE COMPOSITES USING CLASS F FLY ASH AND PCC BOTTOM ASH, AND A STATISTICAL MODEL TO PREDICT COMPRESSIVE STRENGTH OF SIMILAR CONCRETE COMPOSITES ADVISOR: Dr. Sanjeev Kumar It is a common knowledge that the use of concrete is as old as the evolution of human civilization. People have always dreamed beyond the dotted lines and so does the usage of concrete. With the rapid industrialization and globalization, the journey from ordinary concrete to high performance concrete (HPC) has been swift and remarkable. The diversification and utilization of high performance concrete has given the tool in the hands of engineers and architects who can now design and execute buildings of any shape and size deemed impractical a few decades ago. The aim of this research was to develop high performance concrete composites having different percentages of Illinois Class “F” fly ash and bottom ash by replacing the appropriate proportions of Type 1 portland cement and fine aggregate, respectively. The target was to develop high performance concrete composites that have compressive strength of 8,000 psi (55 Mpa) after 28 days of curing in water with a slump of 4±½” (102mm ± 13mm) and air content between 4 and 6 percent. In order to achieve the targeted air content, an air entraining agent DARAVAIR 1400 was used. The water-cement ratio of 0.3 was maintained throughout the research and to achieve the targeted slump, high-range water reducer ADVA 140M was used. The engineering parameters of the high performance concrete composites and an equivalent control mix were evaluated by conducting a detailed laboratory study which included several tests, e.g., slump, fresh air content, compressive strength, splitting-tensile strength, flexural strength, resistance to rapid freezing and thawing, sealed shrinkage and free swelling, and rapid chloride permeability. The results presented show that all high performance concrete composites developed in this study achieved the targeted compressive strength of 8,000 psi (55 MPa) after 28 days of curing in water. The results of the durability tests show that the concrete composites developed in this study have trends similar to that of an equivalent conventional concrete. Based, on the results of this study, it was concluded that the concrete composites have potential to be used on real world projects and thus help the environment by substantially reducing the amount of fly ash and bottom ash going to ash ponds or landfills. Based on the experimental test result data, a detailed statistical analysis was conducted to develop an empirical model to predict compressive strength of similar concrete composites for a given amount of fly ash, bottom ash, and curing period. Additional laboratory tests were performed to validate the mathematical model.

In recent decades, advances in low NOₓ coal combustion and increasingly strict CO₂ reduction mandates have changed power plant boiler operations quite significantly. As a result of these necessary efforts, the characteristics of fly ash generated at many power plants have also changed. In particular, increases in unburned carbon content have been observed with detrimental implications on the utility of these fly ashes in concrete applications. Over the same time period, the combustion of biomass for energy generation has received increased attention due to the potential benefits of reducing CO₂ emissions and improved sustainability when compared to fossil fuel combustion. Biomass is directly burned, gasified, or co-fired with coal to achieve this goal. Currently, close to 120 million metric tons of coal combustion by products are produced in the U.S. annually. As with coal combustion, production of energy from biomass combustion/gasification results in significant by-product generation that must either be productively reused or geologically disposed. While much research effort has been devoted to understanding the properties and potential productive reuse alternatives for coal combustion residuals, relatively little work has been done on the by-products of biomass combustion. This study investigated the properties and engineering behavior of sixteen ash samples that were produced in eleven different power plants. Specifically, three high carbon content Class F fly ashes, eight coal and biomass co-fired ashes, three pure biomass ash samples, and two high quality, low carbon content ash samples, one of which is commercially marketed (for reference) were chosen. The various ash samples were characterized by means of: electron microscopy; laser diffraction and dry sieve particle size analysis; loss on ignition and total organic carbon analysis; specific surface area analysis; as well as x-ray fluorescence and x-ray diffraction. The ash samples were also investigated for their potential engineering application in the fired clay brick industry, as low-cost adsorptive agents, and in alkali activated geopolymer synthesis for geotechnical and geoenvironmental applications. Results from physical and chemical characterization of the ash samples show no significant differences between pure coal ash and coal co-fired with biomass ash samples from the same power plant. However, there are significant morphological, chemical, and mineralogical differences between coal ash and pure biomass ash. Unlike pure coal ash, biomass ash is not composed primarily of aluminosilicate glass cenospheres but rather consists mainly of charred, fibrous woody remnants with elevated calcite content as compared to coal ash. Bench scale fired bricks produced by partial replacement of clay material with high carbon coal ash, co-fired ash, and pure biomass ash, respectively, was successful. Physical properties of a number of the mix designs exceeded the highest ASTM weathering grade requirements. As sorptive agents, high carbon concentrates from coal and co-fired ash samples, along with all the biomass ash samples, showed significant uptake of lead. The unaltered as- received ash samples (i.e. no acid or steam activation) showed only moderate arsenic (V) and selenium (VI) sorption capacity. Finally, solidification/stabilization by geopolymerization of high carbon content, co-fired ash with as little as 3 molar NaOH in the activator solution was successful, possibly paving the way for various geotechnical and geoenvironmental applications in ground improvement and soil/ash-pond stabilization.

I Sverige ökar förbränningen av avfall som inte är ett helt definierbart bränsle. Detta är i mångt och mycket ekonomiskt och miljömässigt försvarbart genom den höga kvalitén på rökasreningen, som garanterar att en mycket liten del av föroreningar når atmosfären, utan dessa koncentreras i askorna. Avfallsaskor går till stor del till deponier och används där för sluttäckning eller för att deponeras, samt att en stor mängd flygaska transporteras till Langöya. Inom en tioårsperiod kommer deponierna vara sluttäckta och Langöya uppfyllt, samtidigt som mängden avfallsaskor ökar, vilket innebär krav på nya lösningar. Orsaken till att framförallt flygaskan klassas som farligt avfall är koncentrationen av tungmetaller och föroreningar som härrör från bränslet. Det har forskat i åratal om metoder som ger miljöriktig användning och metoder för att minska miljöpåverkan från askor, men ytterligare forskning krävs för att få svar på den långsiktiga miljöpåverkan samt alternativa användningsområden. Är avfallsaskorna farligt avfall eller en framtida resurs, en svår fråga att besvara, eftersom det är mycket arbete som behövs ifrån politiker, myndigheter, branschen, forskningen och gemene mans inställning till sopsortering för att lyckas förvandla ett farligt avfall till en resurs.
The combustion of waste is increasing in Sweden and the waste is not an entirely definable fuel. This is very much economically and environmentally defensible by the high quality of smoke purification, which ensures that a very small percentage of pollutants reaching the atmosphere, but on the other hand they are concentrated in the ash. Ashes from the incineration of waste go largely to landfills and are used to cap or to be deposited, and that a large amount of fly ash is transported to Langöya. Within a decade, the landfill will be completed covered and Langöya fulfilled, while the amount of ashes from the incineration are increasing, which would require new solutions. The reason for the particular fly ash as hazardous waste is the concentration of heavy metals and pollutions emanating from the fuel. It has been researched for years about the methods that provide environmentally sound use and methods to reduce the environmental impact of ashes, but further research is needed to find answer to the long-term environmental impact and alternative uses. Are ashes from waste hazardous waste or a future resource, a difficult question to answer, because there is much work needed from politicians, government agencies, industry, research and the general public attitude towards waste separation to successfully transform a hazardous waste into a resource.

Incineration is a mainstream strategy for solid waste management in Sweden and all over the world. Improved knowledge and understanding about the distribution of trace elements (in ashes) during incineration, and how trace element partitioning respond to the changes in waste composition, are important in terms of combustion process optimization and plant efficiency. Moreover, determination of chemical association of trace elements in ashes are vital for avoiding environmental concerns and to promote possible reuse. In this study, partitioning of trace elements in ashes during incineration as function of input waste fuel and incineration technology was investigated. Further, chemical association of trace elements in resulting ashes was studied. An evaluation was also performed about feasibility of metal extraction from sulfidic mining waste and flotation tailings. Moreover, green liquor dreg (GLD) was tested with respect to stabilization of metals within the sulfidic mining waste. Findings showed that the total input of trace elements and chlorine affects the partitioning and increasing chlorine in the input waste caused increase in transfer of trace elements to fly ash especially for lead and zinc. Vaporization, condensation on fly ash particles and adsorption mechanisms play an important role for metal distribution. Firing mixed waste, especially biofuel mix, in grate or fluidized (CFB) boilers caused increased transfer into fly ash for almost all trace elements particularly lead and zinc. Possible reasons might be either an increased input concentration of respective element in the waste fuel, or a change in volatilization behavior due to the addition of certain waste fractions. Chemical association study for fly ashes indicated that overall, Cd, Pb, Zn, Cu and Sb are presenting major risk in most of the fly ashes, while in bottom ashes, most of elements are associated with stable fraction. Further, fuel type affects the association of elements in ashes. Chemical leaching of mining waste materials showed that sulfuric acid (under different conditions) is the best reagent to recover zinc and copper from sulfidic mining waste and also copper from flotation tailings. GLD indicates potential for metal stabilization in mining waste by reducing the metal mobility. Extraction methods could be applied to treat mining waste in order to meet the regulatory level at a specific mining site.Similarly stabilization/solidification  methods might be applied after leaching for recovery of metals.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Doyoyo Mulalo; Committee Member: Will Kenneth; Committee Member: Yavari Arash. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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The aim of this study was to evaluate the eco-efficiency of the transformation of industrial waste in potential profitable co-products, as a business approach to reducing environmental impacts within the supply chain. The paper was based on to the following research question: How to measure the eco-efficiency of companies that value their industrial waste to allocate or offer them as alternative raw material for other industries? In this context, bottom ash resulting from the coal combustion in power plants was evaluated as a alternative raw material replacing sand in the production of ceramic materials and clinker in Portland cement industry, as an approach to eco-efficiency in power plants. The methodological procedures have been carried out in three phases: data collection through interviews; secondary data collection in thesis and periodical articles for the Life Cycle Assessment [LCA] preparation and the data evaluation. Pollutant emissions to atmosphere, water and soil were measured in numerical terms, relating to the production process of electric power and its waste, focused on bottom ash. All pollutants emissions to atmosphere, water and soil in numerical terms relating to the production process of sand and clinker were also measured. The evaluation has been carried out following the ABNT NBR ISO 14045 standard. The inventory calculation was based on primary data collected directly in the studied company and secondary data collected from the literature and regulatory agencies and analyzed by the software SimaPro. Within the limits of this research, it can be inferred that the eco-efficiency measure is carried out in two steps: 1) assessment of environmental impacts through research of the environmental aspects involved in the production process from the extraction of raw materials to the final disposal of waste and compare them to the production process to include the use of such waste. For this evaluation it was essential to measure LCA of waste (or wastes) to be evaluate and to compare the two processes (using and without using residue) so you can check what the major impacts are. Calculate the eco-efficiency of the process; 2) survey the probable cost’s uses of this waste in other production processes so that you can check for a monetary threshold that can afford possible valuation resulting from the new operations additions to the delivery of waste to another industrial sector. Based on these two phases it was possible to established eco-efficiency of the project, from both environmentally and economic perspectives. This research used the ReCiPe endpoint score method that presented the following results: a) Eco-efficiency of the generation of bottom ash for use in the ceramic industry compared with the generation of bottom ash by thermal plant and replacing the sand by the bottom ash in the production of ceramic tiles, thermal plant eco-efficiency spend 0.2% lower to 0.97% higher; b) Eco-efficiency of generation of bottom ash for use in cement industry compared with the generation of bottom ash by thermal plant and replacing the clinker by between 15-50%, have eco-efficiency values ranging from 2.4% to 11.5%. The use of bottom ash total replacement scenario of industrial sand in the production of ceramic tiles can use 91% of the amount spent on the acquisition of sand to buy the bottom ash. The use of bottom ash in the partial replacement scenario clinker in Portland cement production is that 91.4% of the clinker value can be used in the purchase of bottom ash. We can infer that it is possible to measure the eco-efficiency by measuring the environmental impacts through the ACV of the waste and, together, economically test the feasibility of their use.
O objetivo desta pesquisa foi avaliar a ecoeficiência da transformação de resíduos industriais em potenciais coprodutos rentáveis, como uma abordagem empresarial para a redução dos impactos ambientais dentro de uma cadeia de suprimentos. Este trabalho teve como referência a seguinte questão de pesquisa: Como medir a ecoeficiência das empresas que valorizam seus resíduos sólidos industriais ao destiná-los como matéria-prima alternativa para outros setores industriais? Nesse contexto, foi avaliada a valorização de cinzas pesadas, provenientes da combustão de carvão mineral em usinas termelétricas, como matéria-prima alternativa em substituição da areia na produção de materiais cerâmicos e também na substituição do clínquer na indústria de cimento Portland, como uma abordagem de ecoeficiência em termelétricas. Os procedimentos metodológicos foram realizados em três fases: levantamento dos dados por meio de questionários e entrevistas; levantamento de dados secundários em teses e artigos de periódicos para elaboração da Avaliação do Ciclo de Vida [ACV]; e a avaliação dos dados. Foram dimensionadas as emissões de poluentes para atmosfera, água e solo em termos numéricos relativos ao processo produtivo de energia elétrica e seus resíduos, com o foco nas cinzas pesadas. Foram dimensionadas também todas as emissões de poluentes para atmosfera, água e solo em termos numéricos relativos ao processo produtivo da areia e do clínquer. A avaliação foi realizada segundo a norma ABNT NBR ISO 14045. O cálculo do inventário foi baseado em dados primários levantados diretamente na empresa estudada e os dados secundários coletados na literatura e nas agências reguladoras e analisados pelo software SimaPro. No limite desta pesquisa, pode-se inferir que a medida de ecoeficiência seja realizada em duas etapas: 1) avaliação dos impactos ambientais por meio da pesquisa dos aspectos ambientais envolvidos no processo produtivo desde a extração das matérias-primas até a disposição final dos resíduos e sua comparação com o processo produtivo com a inclusão do uso desses resíduos. Para essa avaliação, é fundamental dimensionar a ACV do resíduo (ou dos resíduos) a ser valorizado e comparar os dois processos (sem uso e com do resíduo) para que se possa verificar quais são os maiores impactos. Calcular o valor da ecoeficiência do processo; 2) levantamento dos prováveis custos do uso desses resíduos em outros processos produtivos para que se possa verificar se há uma margem monetária que possa arcar com possíveis valores decorrentes do acréscimo de novas operações até a entrega do resíduo para outro setor industrial. Baseado nessas duas etapas, foi possível estabelecer a ecoeficiência, tanto ambiental quanto econômica do projeto. Esta pesquisa utilizou o método ReCiPe endpoint H pontuação única, que apresentou os seguintes resultados: a) Ecoeficiência da geração de cinzas pesadas para uso na indústria de revestimentos cerâmicos comparada com a geração de cinzas pela termelétrica e a substituição da areia pelas cinzas pesadas na produção de revestimentos cerâmicos, a ecoeficiência da termelétrica passaria de 0,2% inferior para 0,97% superior; b) Ecoeficiência da geração de cinzas pesadas para uso na indústria de cimento comparada com a geração de cinzas pela termelétrica e a substituição do clínquer por cinzas pesadas em quantidades de massa entre 15-50%, têm-se valores de ecoeficiência variando de 2,4% a 11,5%. O uso das cinzas pesadas no cenário de substituição total da areia industrial na produção de revestimentos cerâmicos poderá usar 91% do valor gasto na aquisição de areia para comprar as cinzas pesadas. No uso das cinzas pesadas no cenário de substituição parcial do clínquer na produção de cimento Portland tem-se que 91,4% do valor do clínquer poderá ser utilizado na compra das cinzas pesadas. Pode-se inferir que é possível medir a ecoeficiência medindo-se os impactos ambientais, por meio da ACV do resíduo e, em conjunto, verificar economicamente a viabilidade do seu uso.

Orientador: Waldir Antonio Bizzo
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A cadeia produtiva da cana-de-açúcar tem focado grande interesse no aproveitamento integral dos seus principais subprodutos: a palha e o bagaço (sendo a palha constituída das porções foliares e ponteiras da cana-de-açúcar). Isto tem sido feito através da mudança das rotas produtivas, onde o bagaço será utilizado para a produção de etanol de segunda geração e a palha como substituta do bagaço nas caldeiras de geração de vapor. Atualmente a palha não está consolidada como combustível e, portanto, seu comportamento nos geradores de vapor permanece desconhecido. Sabendo que as incrustações devido à fusão das cinzas durante a combustão de combustíveis sólidos representa um dos maiores problemas na operação dos equipamentos de geração de vapor, neste trabalho, foi caracterizada a palha de cana como combustível a fim de prever seu possível comportamento em caldeiras industriais. Amostras de palha de cana-de-açúcar foram recolhidas em duas condições: diretamente da planta e recolhida no solo após a colheita mecanizada. Foram estudados e analisados os comportamentos das cinzas da palha integral e seus componentes (pontas, folhas verdes e folhas secas), por meio das técnicas de análise térmica simultânea (STA) e da espectrometria de energia dispersiva (EDS). Desta forma, foram identificadas temperaturas de evaporação e a composição dos principais constituintes voláteis das cinzas, representados por uma reação endotérmica com perda de massa. Igualmente, a temperatura de fusão foi detectada como reação endotérmica sem envolver perdas de massa. As análises apresentaram composição e comportamentos diferentes para cada um dos componentes da palha baseados principalmente no teor de metais álcali, cloro e das temperaturas de preparação das cinzas prévias às análises. Neste sentido, as porções correspondentes às pontas e folha verdes da cana-de-açúcar, apresentaram impactos relacionados com incrustações (fouling/slagging) superiores às de folhas secas e palha integral. Baseados nos resultados obtidos a palha de cana-de-açúcar perfila-se como uma possível biomassa substituta ao bagaço nas caldeiras de geração industriais
Abstract: The sugarcane supply chain has lately placed great interest on the comprehensive use of its main by-products: straw and bagasse (the straw constituted by leaves and tops). By changing the production routes, sugarcane bagasse will be used as an energy source for the production of second generation ethanol and straw will substitute bagasse in steam generators. However, sugarcane straw is not currently used as fuel; therefore, its behavior in industrial boilers remains unknown. Slagging and fouling depositions due to fly ash melting within the boiler during combustion of solid fuel represents one of the most significant issues in the operation and maintenance of steam generation equipment. The main objective of this work was to characterize sugarcane straw as a fuel in order to predict its performance in industrial boilers. Samples of straw were collected in two different conditions: directly from the plant and off the field after mechanized harvest. The behavior of the ashes produced at different temperatures (575°C, 785°C and 985/950/850°C) from the integral sugarcane straw and its individual components (tops, dry leaves and green leaves) were analyzed by simultaneous thermal analysis (STA) and energy dispersive spectroscopy (EDS). Evaporation temperature and composition of the main volatile constituents of ashes formed, represented by an endothermic reaction involving changes in mass were identified. Also, fusion temperature was determined to be an endothermic reaction without mass loss. Results showed different elemental compositions and behaviors of ashes for each constituent of sugarcane straw, mainly based on alkali and chlorine percentage, and ashing temperature. In this regard, the fractions corresponding to sugarcane tops and green leaves showed major impacts on slagging and fouling depositions compared to dry leaves and raw straw fraction possibly due to its high levels of potassium and chlorine. Based on the results obtained from this research, sugarcane straw is profiled as an excellent substitute biomass for bagasse in industrial steam generation boilers, instead of being burned as a pre-harvest technique
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica

碩士
國立屏東科技大學
土木工程系所
95
Fly Ash、Sewage Sludge and Bottom Ash of Incinerator are the waste of city development process by various businesses and human daily lives. Many of sciwnce studies show that thecity waste reuse will be a possibility to fill up the shortage of natural resources as sand and cement at this stage. Reusing the waste of Flash Ash、Sewage Sludge and Bottom Ash of Incinerator that will reduce the tension of city environmental protection and build up more benefits for residents of city.The highly reuse the city waste that will enhance the economical efficiency and decrease the city waste treatment of facility. This study Cement weight will be replaced by Fly Ash and Sewage Sludge Ash and as for Incinerator bottom Ash will be replaced by sand. Particularly additional research will be made into the role that fiy ash plays in the drainage of sewage sludge ash.By adding different proportions of fly ash to substitute for the cements used mixed cement mortar will their properities and mechanism has to be changed. Keywords:Fly Ash、Sewage Sludge Ash、Incinerator Bottom Ash

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology
Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution.
Eskom

Tese de Doutoramento em Engenharia Civil
The environmental impact related with the use of several materials in construction sector is in the order of the day. It is well known that the production of Portland cement, one of the materials most used in the construction sector, has a significant contribution to the environmental impacts, mainly related with carbon dioxide emission. Therefore, the study and utilization of by-products or wastes usable as cement replacement in concrete can supply more sustainable options, but maintaining or improving the quality and durability properties of plain cement concrete. Worldwide, coal fly ash (CFA) is the most used supplementary cementitious material in concrete production, mainly because it presents several advantages such as: it is a by-product of coal combustion, is available in great quantities worldwide and is cheaper than Portland cement. Nowadays, coal fly ash is commonly used as cement replacement in concrete from 0 to 40%wt. Using high volumes of these materials has some drawbacks, one of them being the decrease of the pH of concrete thus leading to carbonation issues. In order to understand phenomena such as this, it is important to study the interaction between the mineral additions and hydration of cement and try to find new solutions for the issues related with this type of concrete. The utilization of biomass fly ash (BFA) as partial replacement of cement in concrete production has been studied by several authors and it was verified that this alkaline material can have benefits for concrete. However, its application in high volume fly ash concrete has not been so much studied and because of its characteristics, mainly chemical characteristics, can be a solution to, for example, the carbonation issue of these concretes. So, the main objective of this work was to assess the use of biomass fly ash as cement replacement material or at least as an alkalinity source in high volume fly ash concrete, with a focus on the effect of using biomass fly ash on the quality, durability and sustainable properties, such as: workability, mechanical resistance, resistance to carbonation, resistance to chlorides ions penetration, shrinkage, porosity, leaching of toxic compounds and environmental performance. The results of this study showed that biomass fly ash can improve the properties of high volume fly ash concrete when it is used in small amounts, being the best results verified for 0.5%wt and 1.3%wt of BFA blended with the equivalent proportion of coal fly ash to maintain 50%wt of cement replacement. The two fly ashes seem to have a good synergy in those situations. BFA blended with CFA seems to have a positive contribution on the quality, durability and sustainability of concrete when compared with concrete containing only coal fly ash as supplementary cementitious material or when compared to a plain cement concrete. Thus, with the utilization of BFA, at an industrial level of concrete production, some issues can be minimized, such as the decrease on energy and raw materials consumption related to cement production, and also issues related with the concrete properties and a more sustainable option on the ash management can be applied, than its landfill deposition.
O impacte ambiental relacionado com o uso de diversos materiais no sector da construção está na ordem do dia. É bem sabido, que a produção do cimento Portland, um dos materiais mais usados na construção, tem uma contribuição significativa para os impactes ambientais, essencialmente relacionados com a emissão de dióxido de carbono para a atmosfera. Assim, o estudo e a utilização de subprodutos ou resíduos, usáveis como substitutos do cimento na produção de betão, podem oferecer opções mais sustentáveis, mas mantendo ou melhorando a qualidade e a durabilidade do betão convencional. Por todo o mundo, as cinzas volantes de carvão (CVC) são o material cimentício suplementar mais utilizado na produção de betão, principalmente por apresentarem diversas vantagens, tais como: ser um subproduto da combustão do carvão e estar disponíveis em grandes quantidades, e serem mais baratas do que o cimento Portland. Hoje em dia, as cinzas volantes de carvão são utilizadas em proporções de substituição do cimento de 0-40%m. A utilização de grandes volumes de cinzas tem alguns problemas e um deles é a diminuição do pH do betão que conduz a problemas de carbonatação. Para entender fenómenos como este, é importante estudar a interação entre as adições minerais e a hidratação do cimento e tentar encontrar novas soluções para os problemas relacionados com este tipo de betões. A utilização de cinzas volantes de biomassa (CVB) como um substituo parcial do cimento na produção de betão tem sido estudada por diversos autores e foi verificado que este material alcalino pode trazer benefícios para o betão. Contudo, a sua aplicabilidade em betões com elevado teor de cinzas volantes não foi ainda muito estudada e, devido às sua características, principalmente químicas, pode ser uma solução para o problema da carbonatação destes betões. Assim, o principal objetivo deste trabalho foi o de avaliar se é possível o uso de cinzas volantes de biomassa como substituto material do cimento ou como reservatório de alcalinidade nos betões com elevado teor de cinzas volantes, focando-se no efeito do uso das cinzas volantes de biomassa na qualidade, durabilidade e sustentabilidade, tais como: trabalhabilidade, resistências mecânicas, resistência à carbonatação e à penetração de iões cloretos, retração, porosidade, lixiviação de compostos tóxicos e o desempenho ambiental. Os resultados, obtidos neste estudo, mostraram que as cinzas volantes de biomassa podem melhorar as propriedades dos betões com elevado volume de cinzas volantes, quando utilizadas em pequenas quantidades, sendo os melhores resultados observados para valores de 0.5%m e 1.3%m de CVB misturada com a proporção equivalente de cinzas volantes de carvão, que correspondem a uma substituição de cimento de 50%m. As duas cinzas parecem apresentar uma boa sinergia nestas situações. A mistura das duas cinzas aparenta apresentar uma contribuição positiva na qualidade, durabilidade e sustentabilidade dos betões, quando comparada com betões só com CVC como material cimentício suplementar ou quando comparada com o betão de cimento, sem incorporação de adições minerais. Assim, a utilização das CVB num nível industrial de produção de betão pode resolver alguns problemas, nomeadamente conduzindo à diminuição de energia e matérias-primas consumidas na produção do cimento e, também problemas relacionados com as propriedades do betão, apresentando-se como uma opção mais sustentável para a gestão das cinzas do que a sua deposição em aterro.
Fundo Social Europeu da União Europeia (EU/FSE) através da Fundação para a Ciência e Tecnologia (FCT) que me atribui uma Bolsa de Doutoramento PD/BD/52661/2014, no âmbito do Programa Doutoral ―Eco-Construction and Rehabilitation‖ e no âmbito dos fundos FEDER através do Programa Operacional Competitividade e Internacionalização (COMPETE) e através da Fundação para a Ciência e Tecnologia (FCT) através do projeto POCI-01- 0145-FEDER- 007633 e através do Programa Operacional Regional (CENTRO02020) através do projeto CENTRO-01- 0145-FEDER- 000006. Em especial agradeço ao Programa Doutoral EcoCore, na pessoa do seu Director Professor Jorge de Brito, o qual deu um grande suporte ao trabalho desenvolvido.

碩士
朝陽科技大學
環境工程與管理系碩士班
94
Due to the economical development, municipal solid waste (MSW) has increased to a greater amount as the increase of higher consumption and living standard in Taiwan. MSW treatment has evolved to incineration from landfill due to the difficulty of finding appropriate landfill site in Taiwan. However, residues such as bottom ash and fly ash will still remain 15 % of its original MSW volume. Therefore, residues have become another important issue and need to treat them to prevent secondary pollution in Taiwan. Bottom ash has been utilized as backfill, soil amendment, aggregate and landfill cover. Among them, landfill cover has played a major part for the utilization. However, the baseline data of landfill cover practice is still not fully understood. Thus, using bottom ash as landfill cover needs a deep theoretical and experimental investigation for the understanding of landfill mechanisms. For convenience, fly ash was tested and compared as well. For a short term simulation, six landfill bioreactors with 1 m high and 20 cm wide with working volume of 32 L were used to conduct the experiment. Among them, two was used as control bioreactors containing only the mixture of MSW and seeded sludge. The remained four ones were employed as tested bioreactors the same packing as control ones but with the designated bottom ash and fly ash added ratios of 100 and 200 g l-1 and 10 and 20 g l-1 respectively. These six bioreactors were maintained in a homeostatic oven of 35℃ suitable for the anaerobic digestion. For performance assessment of bioreactors, leachates with 100 mL were sampled for pH, conductivity, salinity, Cl-1, SO4-2 (IC) and metals analyses (ICP-OES). Another 100 mL leachates were recirculated. From the results, it showed that pHs were maintained between 6.5 and 7.5 throught the bioreactor operation with the exception of the first two weeks. 100 g l-1 bottom ash added and 10 and 20 g l-1 fly ash added bioreactors were found to enhance the gas production rate with the highest gas accumulation by 20 g l-1 fly ash added bioreactor. Released alkali metals, heavy metals and trace metals such as Ca, Mg, Ni, Co, Mo etc have been found to have potential beneficial rather than detrimental effects on MSW digestion. Thus, it indicated that proper MSW incinerator bottom and fly ash addition on MSW could increase the MSW decomposition and gas production rate and therefore increased the landfill MSW biostabilization.

碩士
東南科技大學
防災科技研究所
100
This study discusses the mix design with fly ash, bottom ash and FGD gypsum generated by power plant for subbase and base courses. The optimum water contents are to be determined by the analysis of maximum dry density test, compressive strength test, CBR test and permeability test. The mix design for sub-base course and base course are (1) fly ash + bottom ash and (2) fly ash + bottom ash + FGD gypsum, and (3) fly ash + bottom ash + cement and (4) fly ash + bottom ash + FGD gypsum + cement, respectively. The test results are analyzed by the method of Analysis of Variance (ANOVA). The results show that the optimum compositions of the mix design are (1) 40% fly ash + 60% bottom ash and (2) 40% fly ash + 60% bottom ash + 15% FGD gypsum for sub-base course, and (3) 40% fly ash + 60% bottom ash + 5% cement for base course. The optimum water cement ratio of mix design (4) is 0.5. Both the results of mix design (1) and (2) for subbase course can fulfill the requirement of pavement construction. The mix design (2) provides higher bearing capacity and lower permeability coefficient than that of mix design (1). The results of mix design (3) and (4) can fulfill the requirement of cement stabilized base course of pavement specified by the authority of California. The mix design (4) provides a highly compressive strength and lowly permeability coefficient. The coal ash generated from power plant can be effectively utilized by using the mix designs with fly ash, bottom ash, FGD gypsum and cement for sub-base and base courses; and the cost for disposal and treatment of coal ash can be reduced. Keywords: Subbase course, base course, mix design, fly ash, bottom ash, FGD gypsum.

碩士
東南科技大學
防災科技研究所
100
Global economic growth leads to the increasing depletion of natural resources. Rapid increase in population and economic development has resulted in increasing waste production leading to the decline of natural resources. Only the recycling of resources could help achieve sustainable development of the economy and the environment. In recent years, due to nuclear waste disposal problems in domestic nuclear power plants and Japan's tsunami nuclear radiation caused by nuclear energy development, the source of the electricity in the future still relies on coal-fired power plants in short-term supply. Consequently, the ash generated by coal-fired power plants has increased substantially. Therefore the value added re-use of the ash has become essential. This study uses the Taipower production of a large number of fly ash, bottom ash, FGD gypsum ratio tests. The research results show that fly ash, bottom ash, FGD gypsum comply with the road engineering requirements and could be used as backfill alternative materials for road subgrades, achieving the target of resource re-use.

博士
國立中興大學
環境工程學系所
104
The properties of bottom ash and fly ash collected from a fluidized-bed (FB) incinerator for treating general municipal waste and general industrial waste were investigated. These bottom ash and fly ash were used for preparing artificial lightweight aggregates (LWAs) under different operating conditions. The physical properties such as the appearance, expansion rate, density, water absorption, ignition loss, and crushing strength, as well as the leaching rates of toxic heavy metals of these LWAs were explored. Furthermore, the differences of LWAs between the bottom ash and fly ash from a FB incinerator and a mechanical-bed (MB) incinerator were compared and discussed. Experimental results showed that both the bottom ash and fly ash from the FB incinerator can meet the regulation limits of toxicity characteristic leaching procedure (TCLP). However, the fly ash from the cyclone and bag-house of the MB incinerator were identified as toxic wastes due to the concentrations of Cr and Pb over the TCLP regulation limits of Taiwan EPA. For preparing the LWAs, the fly ash from the different incinerators were mixed with the reservoir sediment and sintered. The results showed that the fly ash can be served as a fluxing and foaming agent, and the prepared LWAs can meet the TCLP regulation limits. The maximum mixing percentage of fly ash in the LWAs could be up to 15%. All the physical properties of the LWAs made from the FB fly ash were superior to those made from the MB fly ash. The bottom ash of different incinerators were also used to replace the glass additive and mixed with the fly ash to prepare LWAs. The properties of these LWAs were analyzed and discussed. The results showed that the maximum mixing percentage of bottom ash in the LWAs was within the range of 65 - 75%, and that of fly ash was within 5 - 15%. The highest crushing strength of the LWAs made from the bottom ash and fly ash of the FB and MB incinerators were sintered at 1100oC and 1200oC, respectively. In addition, all the properties of LWAs made from the bottom ash and fly ash of FB incinerator were better than those of the MB incinerator. The operating conditions of waste incinerators are the major factors influencing the physical and chemical properties of bottom ash and fly ash. Owing to the quartz sand being served as the fluidizing media, FB incinerator features the advantages of high mixing extent, high combustion efficiency, low ignition loss, and capturing heavy metals in bed. The concentrations of Si, Al, and Fe in both bottom ash and fly ash of the FB incinerator were high but the concentration of Ca in the fly ash was relatively low. Therefore, the FB fly ash was inherently viewed as the general (non-toxic) industrial waste. They can be directly reused in LWAs without any worry of secondary pollution. In addition, the optimal sintering temperature of LWAs made from the bottom ash and fly ash of the FB incinerator was lower than that made from the ashes of the MB incinerator. Therefore, the bottom ash and fly ash from FB incinerator exhibited superior physical and chemical properties to those of the MB incinerator. The bottom ash and fly ash of the FB incinerator displayed great reusing potentials and possibility.

碩士
國立中興大學
環境工程學系所
102
The application of incinerator fly ash and bottom ash in recycling and reuse is very much. The references by using the Delphi method is also very rare in Taiwan,this study is using this research method for future reference as the motivation. In this study, Delphi method of incineration ash and bottom ash resource recycling applications are considered relative importance for selected assessment questionnaire,to selected iexperts to explore the application of resource reuse factor considerations sort in order choose the best applications. Conclusions are summarized as the assessment dimensions and indicators as below. （1）"Cement raw material substitutes" dimensions include: "environmental impact","engineering efficiency," "safety and health impact", " project performance ","technical reliability" in order for the most important is "project performance.." （2）"Natural aggregates substitutes" dimensions include: "environmental impact","engineering efficiency," "safety and health impact", " project performance ","technical reliability" in order for the most important is impact" and "safety and health impact". （3）" Concrete slabs " dimensions include: "environmental impact", "engineering efficiency," "safety and health impact", " project performance ", "technical reliability" in order for the most important is " engineering efficiency.." （4） Ceramics materials" dimensions include: "environmental impact", "engineering" efficiency," "safety and health impact", " project performance ", "technical reliability" in order for the most important is " safety and health impact." Recommendations for companies are willing to incineration ash and bottom ash recycling resources to assess, it is recommended in the planning process that can follow the above content for self-view to understand where they need to improve in order to enhance the overall quality.

碩士
弘光科技大學
職業安全與防災研究所
97
Bottom ash and fly ash are two major products of ash in municipal solid waste incinerators, and there are many kinds of heavy metals in bottom ash and fly ash, such as Manganese (Mn)、Copper (Cu) and Lead (Pb). Many studies have proved that heavy metals in bottom ash and fly ash are toxic and can cause health effect in human body. The study aims to compare air heavy metal concentrations in bottom ash and fly ash plants of municipal waste incinerator. Furthermore, the study also want to evaluate the heavy metal concentrations in particles with different particle size sampling by IOM (IOM Inhalable Dust Sampler) and Marple (Marple Personal Cascade Impactor) sampler in many departments of the two kinds of plants. One bottom ash recovery and three fly ash treatment plants were recruited in Taiwan. The concentrations of Magnesium (Mg)、Chromium (Cr)、Manganese (Mn)、Iron (Fe)、Cobalt (Co)、Nickel (Ni)、Copper (Cu)、Cadmium (Cd)、Zinc (Zn)、Aluminium (Al) and Lead (Pb) in particles were measured using ICP-OES (ICP-OES-Optima 2100DV). The metals were divided into three groups: first, major metals(Mg、Fe、Al); second, sub-major metals(Cu、Zn、Mn、Pb) and third, minor metals(Cr、Cd、Co、Ni) in bottom ash and fly ash plants. Inhalable particulate concentrations of Mg、Cr、Mn、Fe、Co、Ni、Cu、Zn、Al and Pb in bottom ash plant are obviously higher than those in fly ash. However, Cd levels are higher in fly ash plants than those in bottom ash plant. Heavy metals concentrations in manufacture department are higher than those in storage department of bottom ash recovery plant. Dust characteristics are similar in S and W fly ash factories. Concentrations of Al、Mg、 Cr、 Zn are different between IOM and Marple samplings. Zn and Pb concentrations in fly ash treatment plants of other studies are abundant than those in our studies. Very fine particulates in Fly ash plants are abundant than those in bottom ash plant but opposite to coarse particulates. It should be improved in workers' training on hazards prevention, and to separate work department in bottom ash plant in avoiding heavy metals exposure and to protect the employees’ health.

碩士
淡江大學
水資源及環境工程學系
84
(1) Comparison of Microwave Extraction and Soxhlet Extraction of PCBs inFly Ash and Bottom Ash form MSW Incinerator Because the physical and chemicalproperty of polychlorinated biphenyls (PCBs) are very stable, not resolved bymicroorganism, and they have accumulative toxicity, the EPA announeced thatPCBs is the first place of toxic chemicals, applied and producted areprohibited. But the large number use of PCBs in the early time, they wereenough to harm the health of humanity. When the solid waste contained PCBssuch as capacitors and transfermers were burned in the MSW Incinerators, thetrace PCBs would be producted by clinging to fly ash or bottom, they would beexhausted to pollute the environment. It is first step to extract PCBsefficiently from fly ash and botom ash to the solution before analysing PCBsin them. In this study, a method for sample preparation of halides-organic infly ash and bottom will be assessed, developed and established. In this study,the advatages of the traditional extraction method-Soxhlet extraction andmicrowave extraction method to extract PCBs in fly ash and bottom ash will bediscussed, those depend on the quantitative recovery of PCBs which weredetected by GC/ECD. In the result, the quantitative revocery of PCBs isbetween 42.7 ％ and 75.6 ％ in using the soxhlet extraction method, the otheris betwween 51.6 ％ and 85.8 ％ in using the microwave extraction method. Inthe comparison of efficiency, microwwave extraction method is only cost 10minutes and 30mL solvent. In the analysis of real sample experiment, there arefive fly ash and Bottom ash from MSW Incinerator to be analysed by microwaveextraction. The detective values of PCBs from they is between 0.001ng and9.34ng.(2) Modify Toxicity Characteristic Leaching Procedure (TCLP) －Microwave Extraction the Heavy Metals of Fly Ash Because of the research traceheavy metals of solid waste generally used the toxicity characteristicleaching procedure (TCLP) is required 16-20 hours, it very waste time. In thisstudy, we try to use a noval and rapid method - microwave extraction method tocompare with TCLP. In the result of experiment, Zn is the maximum among allmetals in any kind of fly ash. The lower pH of extraction solution, the moreof leaching metals from fly ash. In the TCLP experiment, there is a verystrange phenomenon. That is the amount of metals which leaching 18 hours isless than which leaching 3 hours, 1hour, and 5 seconds. The reason of thisphenomenon still needs to study after. In the experiment of microwaveextraction, we found that the time is increasing, the amount of metals isdecreasing.

碩士
國立中興大學
土木工程學系所
100
The purpose of this research was to use two materials “Fly ash” and “Bottom ash” that coal-fired power plant produced, using three water-binder ratios (0.70, 0.87, and 1.09), replacing cement doped with fly ash(40%, 50%, 60%, and 70%) and replacing fines content ratios with bottom ash (0%, 12.5 ﹪, 25 ﹪, and 37.5 ﹪) to test early strength CLSM design. Through a series of tests, the research investigated the effects of new mix portions and solid portions of CLSM under different mixed portion conditions and verified the feasibility of the application of coal ash in urban trench backfill project. The results of research showed that : (1) The proportion of early strength ash CLSM, the amount of cement is about 120 ~ 150kg with accelerate coagulation dose about cementing material of 5%-doped reached initial setting in a short period of time and complied with the earlier hard-solid strength requirements. (2) The material-bottom ash with high water absorption characteristics, in the process of mixed portion, the water was easily absorbed by bottom ash lead to poor liquidity. The test found that the rate of the bottom ash was less than 25%, it filled the specifications of the research settings. (3)Since compressive strength depends on the water-binder ratios, compressive strength and water-binder rations varied in inverse portion. With the increase of fly ash replaced cement proportion, the strength reduced obviously. Because the effects of the fly ash changed a lot, the research recommended that the work would work better under these conditions of the water binder ratio 0.7and fly ash ratio among 60~70%, water binder ration 0.87 and fly ash ration among 50~60%, or water binder ratio 1.09 and fly ash ration among 40~50% to meet early strength needs and feasibility. Based on the research of mixed portion design and test results, it was feasible to make ash production become early-strength CLSM. The properties of ash could meet the city pipe trench backfill engineering applications.

碩士
國立中興大學
環境工程學系
93
Currently, a large amount of municipal solid waste is produced through various activities. Landfill has been practiced as the major treatment method in Taiwan. However, this treatment method is extremely constrained to the condiotions that the land is very scarce and the population density is very high in Taiwan. Thus, municipal solid waste incinerator is inevitably chosen as an effectively alternative for MSW treatment. Furthermore, the residues generated from the incinerator still remain 10 % of initial MSW weight and need to be treated further to prevent the secondary pollution. Generally, residues of incinerator are composed of bottom ash and fly ash. Recently, some researches were confirmed that these ashes could be used as a soil cover in landfill and had positive advantage for anaerobic digestion in landfill. However, we know very little regarding the microbial communities in such treatment method. Therefore, molecular technique of fluorescence in situ hybridization (FISH) was applied to investigate microbial community in this study. Combined with the parameter of digestors and VFA concentration, the effect of the microorganisms in anaerobic digestion was explored. According to the result of biogas production amount, the bottom ash addition in the ash/refuse ratio of 100 g/l and the fly ash addition in the ash/refuse ratio of 10 g/l and 20 g/l showed a beneficial effects on anaerobic digestion and accelerated the metaboism of microoranisms and methanogenesis was better than contorl reactors. It was also shown that the proportion of hydrogenotrophic methanogens in all microorganisms were more abundant than aceticlastic methanogens, in which Methanobacterials were dominant hydrogenotrophic methanogens. This indicated that there were vigorous hydrogen production in the reactor adding ashes. And the proportion of sulfate reducing bacteria (SRB) which can compete common substate (H2 and acetate) with methanogens was lower than methanogens, suggesting that SRB would not outcompete methanogens in such evironment and the existence of SRB won’t effect the process of anaerobic digestion. If addition of ashes in landfill was optimum, incinerator bottom ash and fly ash could be used as a soil cover. It had positive beneficial effect to stimunate the process of anaerobic digestion and it could increase the efficiency of methanogenesis. Therefore, the method of codigestion of MSW and ashes was demonstrated a efficicent way for biological resouces.

碩士
國立中央大學
環境工程研究所
82
Due to its dense population, limited land for waste disposal, and increases in per capita waste generation, Taiwan is entering a phase of applying incineration technology as an alternative to landfills for municipal solid waste (MSW) management. However, the potential emission of toxic heavy metals from MSW incinerators into the environment may pose serious threats on human health and ecology. This issue has not been properly addressed and has caused more public concerns in Taiwan recently since the concept of separation and recycling of refuse is not generally adopted and the incinerators for hazardous wastes are not commonly available here. In this study, the concentrations of some heavy metals (including Hg, Cd, Pb, and Zn) which exist in fly ash and bottom ash coming out of a typical MSW incinerator located in northern Taiwan were determined. Furthermore, the physical properties, such as particle size, surface area, and porosity of fly ash were also characterized for better understanding of their potential effects on the concentration of these heavy metals. Preliminary results indicate that the concentrations of mercury, cadmium, and zinc are generally higher in fly ash than that found in bottom ash. In fact, the property of municipal solid wastes, varying operating conditions within incinerators, combustion efficiency, and chloride content in the flue gas streams all affect the partitioning of heavy metals among flue gas, fly ash and bottom ash. As a result, the concentration of heavy metals contained in fly ash may vary with different particle size. In this study, collected fly ash was segregated into seven different fractions based on particle size (Mesh 50-Mesh 325). Analysis of particles with each fraction indicates that particles around Mesh 50/80 with a specific area of about 6 m2/ g tend to adsorb more heavy metals (including Hg, Cd, Pb, and Zn) than the particles with other sizes.

碩士
弘光科技大學
職業安全與防災研究所
96
The fly ash and ambient emissions of municipal solid waste incinerators are known to contain polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), other organics, metals and gases. Hazardous substances such as PCDD/Fs, other silicates and heavey metals, the components of bottom ash and fly ash, have been shown to elevate the oxidative damage in epidemiological and toxicity studies. The study aimed to compare oxidative damage in workers who have potentially been exposed to hazardous substances at a bottom ash recovery plant and fly ash treatment plants in Taiwan by measuring the levels of DNA strand breaks (tail moment), plasma MDA and urine 8-hydroxy-2’-deoxyguanosine (8-OH-dG). Thirty-seven workers were recruited from a bottom ash recovery plant and forty-one workers from fly ash treatment plants in Taiwan. Urinary 8-OH-dG levels were determined using a competitive ELISA immunoassay. Plasma lipid peroxidation was measured as the MDA levels by a fluorescence spectrophotometer. The tail moment was considered as DNA strand breaks by comet assay (single cell gel electrophoresis or SCEG). Significantly higher MDA levels and DNA strand breaks (tail moment) both were found in the workers of fly ash treatment plant than those in bottom ash plant (3.20 μM and 0.58 μM, p<0.0001; 7.55 and 2.64, p<0.0001). The data also indicated a significant association between the MDA levels and tail moment of workers and their working plant, especial for fly ash treatment plant. Significant higher levels of MDA, 8-OH-dG and tail moment were found only in participants who had been working at the plants for more than 2.5 years. After adjusted for smoking, age, alcohol drinking and working periods, significantly higher MDA levels and tail moment both were found in the workers of fly ash treatment plants than those in bottom ash plant. We suggested the higher lipid peroxidation and DNA strand breaks in fly ash treatment plants than in bottom ash plant. We also found that workers exposed to ash did not use protective equipments, which seemed to be the main factor resulting in DNA damage. The data concluded that an elevated tail migration may be expected in workers at fly ash treatment plants than in those at bottom ash plants. In addition, large quantities of dioxins and metals may leach from fly ash than bottom ash, the data indicate that the workers of the fly ash treatment plant should be paid more attention to avoid exposing to fly ash.

This dissertation considers the behaviour of particulate fly ash produced during cocombustion experiments of biomass materials with pulverized coal in a 1 MWth pilotscale combustion test facility (PSCTF). Particular attention is generally given to fly ash particles of diameters less than 10 and 2.5 microns (namely PM10 and PM2.5). These small particles have the potential for affecting human health and forcing climate change because of their ability to scatter and absorb light and also to act as cloud condensation nuclei. South African coal has high ash content that consequently affects the ash burden and the efficiency of ash removal system. Previous research work reports increase of the concentration of fine particles during the co-firing of biomass with coal, thus limiting the amount of biomass co-fired. Coal and two types of biomass, grass and sawdust, were used in this study. The coal chosen was representative on the basis of the annual average calorific value of coals burned at ESKOM’S coal-fired power stations. For each biomass, the ratios of biomass to coal used on an energy basis were 10%:90%, 15%:85% and 20%:80%, resulting in a total of seven different tests including coal alone. Seven tests with similar fuels were also carried out using a drop tube furnace (DTF) to determine their reaction kinetics for the combustion simulation. The experimental results revealed that the grass and sawdust blends showed decreases of PM10, and PM2.5 particles percentages compared to the coal baseline. The grass because of its high content of alumina-silicate showed considerable agglomeration whereas sawdust blends gave minor increase of PM10 under high pressure condition inside the combustion chamber. The pulverised-coal fineness, flue gas temperature and excess air were found to affect the particulate matter behaviour. The fly ash samples collected were also analysed by scanning electron microscope and spectrometry; alkali metals released were observed to react with the alumino-silicate phase. The fine sulphate enriched particles formation during combustion process was 4 modelled based on the Glarborg-Marshall mechanism using CFD tool. The simulation results were validated by the experimental data from the pilot-scale combustion test facility.

碩士
國立屏東科技大學
環境工程與科學系所
96
The research studies the lead concentration and distribution of trash ash applying commercial wastes toxic characteristic leaching procedure (TCLP) in order to understand the physical properties of trash ash in Taiwan. Phosphorite and Municipal Solid Waste Incineration (MSWI) are adopted and because the heavy metal components of trash ash are formed including copper, the stabilization of lead, chromium, cadmium, and zinc, etc…in trash ash, produced and the heavy metal is converted into tsumebite. This situation can avoid the release of heavy metal from ash. In addition, the research also controls the surface temperature of polyphosphate in phosphorite within 75 to 100 ℃. In about one month, the loose structure of phosphorite is formed the dough structure. This shows the temperature can be controlled by means of incinerator wasted heat.

碩士
淡江大學
水資源及環境工程學系
87
Ⅰ. Characterization and Removal of Radionuclide 60Co from the Sediment Using Microwave Energy The goals of this study are to characterize the radionuclides 60Co absorbed on soil and to remove this metal from contaminated soil by microwave treatment. This study is concentrated on the application of microwave oven for chemical extraction of radionuclide 60Co in soil. The various experimental condition (microwave power, organic reagents, chelating agent, extraction time, and extraction sequences) were explored and optimized to improve the removing efficiency. The results showed that the removal of 60Co was 42.76% after microwave treatment with ammonium oxalate solution. However, the microwave removing efficiency of 60Co with ammonium oxalate solution twice were improved and increased to 72.37%. The microwave treatment has advantages of simple operation, decrease processing time and low cost equipment required. Ⅱ.A Study for Determination of Copper, Lead, Cadmium, Nickel and Chromium in Fly Ash and Bottom Ash from Municipal Waste Incinerator by Microwave Digestion with Inductively Coupled Plasma-Atomic Emission Spectrometry The traditional techniques for sample preparation such as alkaline fusion and aqua regia dissolution will take many hours to digest the ash samples. In contrast, the samples digested by microwave energy are fast due to the increased heating that occurs from the microwave interaction with the reagents and samples. Therefore, microwave digestion procedures are becoming more popular as they considerably reduce the amount of time spent preparing the sample for the spectrometric analysis. This study was based on modified USEPA Method 3052 and the operating conditions as microwave power, the type and the concentration of acids, the numbers of digestion and digestion time were explored and optimized to digest the ashes from municipal waste incineration completely. The conditions of microwave digesting methods were as following: 0.2g sample was weighed into a vessel and added with 3mL HNO3, 1mL each of HCl and HF. The microwave digestion system was programmed as that of Method 3052. After completion of the microwave program and cooling to room temperature, 10mL of H3BO3 was added to the vessel. The system was programmed again as the same parameters. The results were in good agreement with certified reference material (BCR No. 176), and successfully applied to the determination of copper, lead, cadmium, nickel and chromium in fly ash and bottom ash from municipal waste incineration.

Μεγάλο τμήμα της παραγόμενης ενέργειας στην Ελλάδα προέρχεται από την καύση λιγνίτη στην Βόρεια (Δυτική Μακεδονία) και Νότια (Πελοπόννησος) Ελλάδα. Η καύση του λιγνίτη έχει ως αποτέλεσμα την παραγωγή μεγάλων ποσοτήτων στερεών παραπροϊόντων, όπως η ιπτάμενη τέφρα (ΙΤ) και η τέφρα πυθμένα (ΤΠ), των οποίων η συνολική παραγωγή ανέρχεται σήμερα σε 14Mt ετησίως. Η ποσότητα των παραπροϊόντων αυτών αναμένεται να αυξηθεί τα επόμενα χρόνια εξ’ αιτίας της συνεχώς χαμηλότερης ποιότητας λιγνίτη που χρησιμοποιείται (χαμηλότερη θερμογόνος δύναμη). Ένα τμήμα της παραγόμενης ΙΤ (10-12%) στην Ελλάδα αξιοποιείται ως πρώτη ύλη στη παραγωγή τσιμέντου, ενώ η ΤΠ δεν απορροφάται μέχρι σήμερα από καμία εφαρμογή, κυρίως λόγω του υψηλού ποσοστού άνθρακα που περιέχει. Το αντικείμενο της παρούσας διατριβής είναι η αξιοποίηση, πρωτίστως, της ΤΠ και, μετέπειτα, της ΙΤ ως πρώτες ύλες στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στην παραγωγή ελαφροσκυροδέματος. Για την παραγωγή των τεχνητών ελαφροαδρανών εφαρμόστηκε η διεργασία της πυροσυσσωμάτωσης σε σχάρα (grate sintering) έπειτα από σφαιροποίηση μιγμάτων των δύο τεφρών. Πραγματοποιήθηκε διερεύνηση των φυσικοχημικών χαρακτηριστικών των λιγνιτικών τεφρών (Κεφάλαιο 2) με σκοπό τον προσδιορισμό και την κατανόηση των χαρακτηριστικών τους, τα οποία αναμένεται να έχουν σημαντική επίδραση στην εφαρμογή της διεργασίας και στην ποιότητα του παραγόμενου προϊόντος. Επιπλέον, γίνεται αναλυτική αναφορά στα βασικά χαρακτηριστικά των διεργασιών σφαιροποίησης και πυροσυσσωμάτωσης (Κεφάλαιο 3). Για την εφαρμογή της επιλεγμένης διεργασίας παραγωγής τεχνητών ελαφροαδρανών πραγματοποιήθηκε σχεδιασμός μιγμάτων με διαφορετικές αναλογίες ΤΠ και ΙΤ (Κεφάλαιο 4). Ο περιεχόμενος άνθρακας της ΤΠ αποτελεί το καύσιμο της διεργασίας πυροσυσσωμάτωσης, ενώ η υψηλή περιεχόμενη υγρασία της ΤΠ αξιοποιείται ως το κύριο συνδετικό υλικό κατά την διάρκεια σφαιροποίησης για τον σχηματισμό σφαιριδίων. Οι διαφορετικές αναλογίες ΤΠ και ΙΤ αντιστοιχούν σε διαφορετικό ποσοστό στερεού καυσίμου στο μίγμα (προκύπτει από τις διαφορετικές vi αναλογίες), μία παράμετρος η οποία έχει επίδραση στην ολοκλήρωση της πυροσυσσωμάτωσης και στην ποιότητα του παραγόμενου (ελαφροαδρανούς) προϊόντος. Η πυροσυσσωμάτωση ολοκληρώθηκε με επιτυχία με ελάχιστο ποσοστό στερεού καυσίμου (περιεχόμενο άνθρακα ΤΠ) 6.5%κβ (Κεφάλαιο 5). Πραγματοποιήθηκε φυσικοχημικός χαρακτηρισμός όλων των προϊόντων της πυροσυσσωμάτωσης των μιγμάτων λιγνιτικών τεφρών της Μεγαλόπολης, και διαπιστώθηκε ότι το ποσοστό περιεχόμενου άνθρακα της ΤΠ είναι μια πολύ σημαντική παράμετρος για την παραγωγή ελαφροαδρανών υλικών. Ο σχηματισμός πορώδους δομής στο εσωτερικό των πυροσυσσωματωμένων πελλετών, στην οποία οφείλεται και το χαμηλό βάρος των παραγόμενων αδρανών, προκαλείται από την ταυτόχρονη εξέλιξη δύο διεργασιών: α) την παραγωγή αερίων σε υψηλές θερμοκρασίες και β) τον σχηματισμό ρευστής φάσης στην εξωτερική επιφάνεια της πελλέτας στο ίδιο χρονικό διάστημα (Κεφάλαιο 6). Οι αντοχές των πυροσυσσωματωμένων πελλετών οφείλονται σε αντιδράσεις και στον σχηματισμό νέων φάσεων είτε στερεών μέσω διάχυσης είτε ρευστών που προέρχονται από επιτήξεις στα όρια των κόκκων. Στην συνέχεια τα παραγόμενα ελαφροαδρανή χρησιμοποιήθηκαν για την παραγωγή δοκιμίων θερμομονωτικού και δομικού ελαφροσκυροδέματος και πραγματοποιήθηκε έλεγχος των θερμικών και μηχανικών τους ιδιοτήτων, αντίστοιχα (Κεφάλαιο 7). Τα αποτελέσματα δείχνουν ότι τα τεχνητά ελαφροαδρανή μπορούν να χρησιμοποιηθούν για την παραγωγή θερμομονωτικού και δομικού ελαφροσκυροδέματος. Η επιτυχής παραγωγή τεχνητών ελαφροαδρανών από μίγματα λιγνιτικών τεφρών Μεγαλόπολης αποτέλεσε και την βάση για δοκιμές πυροσυσσωμάτωσης των παραπροϊόντων αυτών με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ερυθρά ιλύς (ΕΙ), η οποία παράγεται από την επεξεργασία βωξίτη προς παραγωγή αλουμινίου (Κεφάλαιο 8). Για την διαπίστωση της συνεργασίας των δύο διαφορετικών παραπροϊόντων πραγματοποιήθηκε προσθήκη μέχρι και 30%κβ ΕΙ σε μίγματα λιγνιτικών τεφρών. Πραγματοποιήθηκε φυσικοχημική διερεύνηση των προϊόντων της πυροσυσσωμάτωσης και χρήση τους στην παραγωγή δοκιμίων σκυροδέματος. Τα αποτελέσματα δείχνουν ότι η αύξηση της προστιθέμενης ΕΙ στο μίγμα λιγνιτικών vii τεφρών της Μεγαλόπολης επιφέρει αύξηση στο βάρος των παραγόμενων αδρανών, ενώ μπορούν να χαρακτηριστούν ελαφροαδρανή τα προϊόντα πυροσυσσωμάτωσης μιγμάτων μέχρι και 20%κβ προσθήκης ΕΙ. Τα αποτελέσματα των μετρήσεων των μηχανικών αντοχών των δοκιμίων σκυροδέματος δείχνουν ότι η ΕΙ επιφέρει αύξηση στις αποκτώμενες αντοχές σε ποσοστό προσθήκης μέχρι και 15%κβ. Η εφαρμογή που προτείνεται σε αυτή την διατριβή για την παραγωγή τεχνητών ελαφροαδρανών υλικών από τα στερεά λιγνιτικά παραπροϊόντα του ΑΗΣ Μεγαλόπολης αποτελεί την πρώτη πρόταση για αξιοποίηση της ΤΠ στην Ελλάδα. Η πυροσυσσωμάτωση μιγμάτων των λιγνιτικών τεφρών μπορεί να οδηγήσει στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στο δομικό και θερμομονωτικό ελαφροσκυρόδεμα ενώ ο περιεχόμενος άνθρακας της ΤΠ, ο οποίος αξιοποιείται ως το καύσιμο διεργασίας παραγωγής, αποτελεί σημαντική παράμετρο για την ποιότητα των τεχνητών ελαφροαδρανών. Επιπλέον, οι λιγνιτικές τέφρες της Μεγαλόπολης μπορούν να συνεργαστούν με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ΕΙ για την παραγωγή τεχνητών ελαφροαδρανών διαφορετικής ποιότητας. Επίσης, η συγκεκριμένη πρόταση αφορά στην μαζική αξιοποίηση της ΤΠ και πιθανή εφαρμογή έχει την δυνατότητα να απορροφήσει το μεγαλύτερο τμήμα του παραγόμενου αυτού παραπροϊόντος.
Large part of energy demand in Greece is covered by lignite combustion in West Macedonia and Peloponnesus. Lignite combustion results in production of, approximately, 14Mt/year of solid byproducts, such as fly ash (FA) and bottom ash (BA). The quantity of these byproducts is going to be increased in future because of the low quality of available lignite (lower calorific value). Part of FA (10-12%) produced in Greece is utilized as raw material in cement production while there is no application of BA, mainly because of its high carbon content. This study investigates a new method for utilization of BA, primarily, and FA, afterwards, as raw materials in the production of lightweight aggregates and further utilization of produced aggregates in lightweight aggregate concrete. A two stage process, pelletization and sintering, is applied in BA and FA mixtures. Physical and chemical analyses of Megalopolis lignite ashes are performed (Chapter 2) in purpose of characterization of process raw materials. Furthermore, fundamental theory of pelletization and grate sintering is presented (Chapter 3) in purpose of better understanding of process details. Mixtures of different BA/FA ratio are prepared for sintering tests (Chapter 4). Carbon contained in BA is utilized as the fuel of the process, while high water content of BA is utilized as the primary binding material during pelletization in purpose of pellets formation. Different BA/FA ratios represent different solid fuel percentages in sintering mixtures. This is an important parameter, which strongly affects the completion of the process and the quality of product. Successful completion of sintering process is achieved with minimum solid fuel content (BA carbon) 6.5wt% in mixture (Chapter 5). Physical and chemical characterization is performed for products of all different sintering mixtures. The results show that BA carbon content is an important parameter for the production of lightweight aggregates. Porous structure formation inside the sintered pellets, which is responsible for aggregates low weight, is caused by simultaneous development of two different processes: a) production of gases in high temperatures and, b) liquid (glassy) phase formation in the outer part of pellets in the same time period (Chapter 6). ix Formation of either solid state bonds, through diffusion, and/or glassy phase bonds at the points of particles mutual contact are responsible for pellet strength. Lightweight aggregates produced are used in the production of insulating and structural lightweight aggregate concrete specimens and thermal and mechanical tests are performed, respectively. According to tests results artificial lightweight aggregates can be used for insulating and structural purposes. The successful experimental results from the utilization of lignite solid byproducts in the production of LWA offered new opportunities for collaboration of these byproducts with other industrial solid residues, such as red mud (RM) which is produced during bauxite treatment for aluminum production (Chapter 8). In purpose of investigation of collaboration of these different byproducts sintering mixtures are prepared with low RM addition, up to 30wt%, in lignite ashes mixtures. Physical and chemical characterization is performed for products of all sintering mixtures and they are used for production of concrete specimens. Results show that increase of RM addition brings increase in aggregates weight, while aggregates formed by RM addition up to 20wt% can be considered as lightweight ones. The results of mechanical strength tests in concrete specimens show that RM addition up to 15wt% brings increase in aggregates strength. This is the first proposed method for utilization of lignite BA in Greece in the production of lightweight aggregates. Sintering of mixtures of lignite ashes results to the production of lightweight aggregates and the produced aggregates can be used for insulating and structural lightweight aggregate concrete. BA carbon content, which is utilized as the fuel of the process, is an important parameter for lightweight aggregate production and porous structure formation. Furthermore, Megalopolis lignite ashes can be treated in collaboration with other industrial solid byproducts, such as RM for the production of lightweight aggregates of different quality. Finally, the proposed method targets to massive utilization of BA produced in Megalopolis power station.

Dissertação de mestrado integrado em Engenharia Civil
A sustentabilidade da construção é um assunto com grande influência e consequências na atualidade. Uma das medidas de modo a contribuir para a sustentabilidade é reduzir a produção e o consequente consumo de cimento que deriva da construção. A produção de cimento Portland origina a libertação de grandes quantidades de CO2 e consome grandes quantidades de energia. Como o betão é utilizado na construção em grandes quantidades, pode ser utilizado de maneira a nele serem incorporados resíduos e subprodutos industriais de forma segura e económica. Um exemplo é a incorporação de cinzas volantes de carvão provenientes de centrais termoelétricas. Betão com um elevado volume de cinzas volantes, possui uma reação pozolânica lenta e, portanto, a resistência mecânica inicial do betão é menor que o betão com cimento como único ligante. O destino de valorização mais comum dos resíduos florestais é a sua valorização térmica através da combustão. As cinzas volantes de biomassa têm características semelhantes às cinzas volantes de carvão, no entanto, são mais alcalinas (maior pH) e possuem um teor de cálcio maior. O principal objetivo deste trabalho consiste em avaliar a possibilidade de produzir betões de desempenho melhorado incorporando elevado volume de cinzas volantes de carvão, bem como utilizar pequenas quantidades de cinzas volantes de biomassa, de forma a mitigar alguns dos inconvenientes dos betões com elevado volume de cinzas volantes de carvão. Com base nos resultados obtidos, a durabilidade das composições com elevado volume de cinzas volantes, revelou-se, em geral, superior à da composição de referência, com exceção relativamente à resistência à carbonatação que, contudo, foi melhorada com a inclusão de uma reduzida quantidade de cinzas de biomassa. A cinza volante de carvão possuiu uma boa sinergia com quantidades reduzidas de cinza de biomassa que resultou numa boa atividade pozolânica.
The sustainability of construction is a subject with great influence and consequences at the present time. One of the measures to contribute to sustainability is to reduce the production and consequent consumption of cement that comes from construction. The production of Portland cement gives rise to the release of large amounts of CO2 and consumes large amounts of energy. As concrete is used in large-scale construction, it can be used to incorporate industrial waste and by-products in a safe and economical way. An example is the incorporation of coal fly ash from thermoelectric power plants. Concrete with a high volume of fly ash has a slow pozzolanic reaction and, therefore, the initial mechanical strength of the concrete is lower than the concrete with cement as the sole binder. The most common destination for forest residues is their thermal recovery through combustion. Biomass fly ash has characteristics similar to coal fly ash, however, they are more alkaline (higher pH) and have a higher calcium content. The main objective of this work is to evaluate the possibility of producing improved performance concrete incorporating a high volume of coal fly ash, as well as to use small amounts of biomass fly ash to mitigate some of the drawbacks of concretes with high volume of coal fly ash. Based on the obtained results, the durability of the compositions with a high volume of fly ash has generally proved to be superior to that of the reference composition, except for the resistance to carbonation which has however been improved by the inclusion of a reduced amount of biomass ash. Coal fly ash had a good synergy with reduced amounts of biomass ash which resulted in good pozzolanic activity.

Cement-based concrete is one of the main construction materials that is widely used for many construction applications due to its strength, durability, reflectivity, and versatility. However, it is acknowledged that production of cement as a primary material of concrete releases 1.8 Gt carbon dioxide (CO2) into the environment. It is estimated that one ton of cement production releases one ton of CO2 to the atmosphere. That is why, this work aims to create a concrete that could be an alternative to cement-based concrete. Geopolymer concrete (GPC) is an eco-friendly construction material and an alternative to conventional concrete that is produced by reacting aluminate and silicate bearing constituents with a caustic activator (i.e. sodium-based or potassium-based). Both potassium and sodium have been considered as generally safe intergradient by the FDA, based upon the observance of several good manufacturing practice conditions of use. Theses activators are used in various application including concrete, food, as a stabilizer, and as a thickening agent. Moreover, these activators are also used in making soap, as an electrolyte in alkaline batteries and in electroplating, lithography, and paint and varnish removers. Medically, these activators are widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions, Currently, it was determined that these activators solution were found to be a safe and effective treatment of plane warts. Despite the developments in the studies relating to GPC made by various precursors such as fly-ash and slag in the literatures, the use of GPC made by fly-ash and bottom-ash has not been overly researched. In this study, attempts have been made to produce a unique mix proportion for Potassium-based GPC made by fly-ash and bottom-ash and investigate various mechanical properties of this type of GPC including elastic modulus, freeze-thaw resistance, heavy metal leach-ability and corrosion in both laboratory and real environmental conditions using Non-Destructive Tests (NDT)s.
Graduate
2021-12-15

Although products of coal combustion (PCCs) such as coal ash are currently exempted from classification as a hazardous waste in the United States under the 1976 Resource Conservation and Recovery Act (RCRA), the U.S. Environmental Protection Agency (EPA) is now revising a proposed rule to modify disposal practices for these materials in order to prevent contamination of ground- and surface water sources by leached trace elements. This paper analyzes several aspects of EPA’s scientific reasoning for instating the rule, with the intent of answering the following questions: 1) Are EPA’s cited values for PCC production and disposal accurate estimates of annual totals?; 2) In what ways can EPA’s leaching risk modeling assessment be improved?; 3) What is the total quantity of trace elements contained within all PCCs disposed annually?; and 4) What would be the potential costs and feasibility of reclassifying PCCs not under RCRA, but under existing NRC regulations as low-level radioactive waste (LLRW)? Among the results of my calculations, I found that although EPA estimates for annual PCC disposal are 20% larger than industry statistics, these latter values appear to be closer to reality. Second, EPA appears to have significantly underestimated historical PCC disposal: my projections indicate that EPA’s maximum estimate for the quantity of fly ash landfilled within the past 90 years was likely met by production in the last 30 years alone, if not less. Finally, my analysis indicates that while PCCs may potentially meet the criteria for reclassification as low-level radioactive waste by NRC, the cost of such regulation would be many times that of the EPA June proposed disposal rule ($220-302 billion for PCCs disposed in 2008 alone, versus $1.47 billion per year for the Subtitle C option and $236-587 million for Subtitle D regulatory options).
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Μία από τις σημαντικότερες αποθέσεις λιγνίτη της Δυτικής Τουρκίας εντοπίζεται στην λεκάνη της Mugla. Η λεκάνη της Mugla αποτελείται από δύο τάφρους ΒΔ-ΝΑ διεύθυνσης, οι οποίες χωρίζονται από μία πλατιά έξαρση του υποβάθρου, δημιουργώντας τις υπολεκάνες του Yatağan και του Milas. Η εμφάνιση του υποβάθρου αποτελείται στα νότια από τα Λυκκιακά καλύμματα, τα οποία περιλαμβάνουν ένα σύμπλεγμα πετρωμάτων ωκεάνιας και ηπειρωτικής προέλευσης και στα βόρεια από μεταμορφωμένα πετρώματα, όπως σχιστόλιθοι, γνεύσιοι, αμφιβολίτες, και μάρμαρα της Μάζας Menderes. Η παρούσα εργασία εστιάζει στο λιγνίτη της περιοχής Milas και τα στερεά παραπροϊόντα καύσης του (ιπτάμενη τέφρα και τέφρα εστίας) από τις περιοχές Yeniköy, Yatağan και Kemerköy της Τουρκίας. Σκοπός της μελέτης είναι η εκτίμηση της κινητικότητας των ιχνοστοιχείων κατά την εκμετάλλευση του λιγνίτη για ηλεκτροπαραγωγή και κατά την αποθήκευση και διάθεση των στερεών παραπροϊόντων της καύσης του στην περιοχή Mugla της Τουρκίας. Αντικείμενο της εργασίας αποτέλεσε η γεωχημική μελέτη του λιγνίτη και των παραπροϊόντων του, καθώς και η χημική μελέτη των διαλυμάτων που προέκυψαν κατά την απόπλυσή τους σε συνθήκες pH 5 και 8,5. Επιπρόσθετα, πραγματοποιήθηκε μία σειρά εργαστηριακών αναλύσεων, που περιλαμβάνουν την προσεγγιστική και στοιχειακή ανάλυση, την ανθρακοπετρογραφική εξέταση, καθώς και τις ορυκτολογικές αναλύσεις όλων των δειγμάτων. Στα πλαίσια των εργαστηριακών αναλύσεων, προσδιορίστηκε η υγρασία, η τέφρα, η περιεκτικότητα σε πτητικά συστατικά, καθώς και η περιεκτικότητα των C, H, N και S του λιγνίτη και των παραπροϊόντων του, ο μόνιμος άνθρακας, η θερμαντική ικανότητα και η ανακλαστικότητα του λιγνίτη. Οι συγκεντρώσεις των ιχνοστοιχείων στον λιγνίτη, την ιπτάμενη τέφρα και την τέφρα εστίας προσδιορίστηκαν με τη χρήση του οργάνου ELAN 6100 Perkin Elmer®. Τα στοιχεία, που προσδιορίστηκαν είναι τα Αg, As, B, Ba, Be, Co, Cr, Cu, Fe, Ga, Hf, Hg, Li, Mn, Mo, Ni, Pb, Se, Sr, U, V και Zn. Σύμφωνα με τις περιεκτικότητες των ιχνοστοιχείων του λιγνίτη και των παραπροϊόντων της καύσης του εκτιμήθηκε η κινητικότητά τους κατά την καύση με τον υπολογισμό του συντελεστή εμπλουτισμού (R.E.). Πολύ μικρό συντελεστή εμπλουτισμού και κατά συνέπεια έντονη πτητικότητα παρουσιάζουν τα στοιχεία As, Cd, Mo, Pb και Sr. Μέτρια πτητικότητα εμφανίζουν τα Ag, B, Cr, Ni, U, V, Zn, ενώ όλα τα υπόλοιπα έχουν μικρή πτητικότητα, καθώς συμμετέχουν στο τμήμα των παραπροϊόντων που παραμένει στην τέφρα των ατμοηλεκτρικών σταθμών. Ακολούθως, έλαβαν χώρα πειράματα έκπλυσης των ιχνοστοιχείων από το λιγνίτη και τα παραπροϊόντα του σε συνθήκες pH 5 και 8,5, ούτως ώστε να προσδιοριστεί η κινητικότητα τους, με τη βοήθεια του Ποσοστού Σχετικής Έκπλυσης (RML) και της Έντασης έκπλυσης (Ιl). Τα αποτελέσματα των παραπάνω έδειξαν ως πιο κινητικά ιχνοστοιχεία σε συνθήκες pH 5 και 8,5, στο λιγνίτη τα As, B, Mn, Sr, στην ιπτάμενη τέφρα τα Cr, Li, Mo και Sr, και στην τέφρα εστίας τα Li, Mo, Sr. Προκειμένου να προσδιοριστεί η γεωχημική συγγένεια των ιχνοστοιχείων στα «ως έχει» δείγματα του λιγνίτη και των παραπροϊόντων καύσης του, αλλά και να περιγραφεί η συμπεριφορά τους κατά τη διάρκεια της έκπλυσής τους σε διαφορετικές τιμές pH, πραγματοποιήθηκε στατιστική επεξεργασία των αποτελεσμάτων της στοιχειακής ανάλυσης. Ειδικότερα, στα αποτελέσματα των στοιχειακών αναλύσεων και των τιμών έκπλυσης των ιχνοστοιχείων όλων των δειγμάτων ξεχωριστά για pH 5 και pH 8,5, καθώς και των ορυκτών της ιπτάμενης τέφρας και της τέφρας εστίας εφαρμόστηκε η μέθοδος της παραγοντικής ανάλυσης R-τύπου.
One of the most important lignite deposits of Western Turkey is located in the basin of Mugla. The Mugla basin consists of two NW-SE direction grabens, which are separated by a wide rise of the basement that creates the sub-basins of Yatağan and Milas. Southern, the basement is consisted of the Lyccian nappes, which contain a cluster of ocean and continental origin rocks, while northern is consisted of metamorphic rocks, such as schists, gneiss, amphibolites and marbles of the Menderes Mass. The present study focuses on the lignite of Milas region and its combustion solid by-products (fly ash and bottom ash) from Yeniköy, Yatağan and Kemerköy areas in Turkey. The purpose of this study is to estimate the mobility of elements and trace elements in the exploitation of the lignite deposits for generating power in the region of Mugla in Turkey. The object of the present study lies in the geochemical study of lignite and its combustion products and in the determination of the mobility of trace elements during the combustion of lignite and the leaching of lignite and its by-products, under pH 5 and 8.5 conditions. In addition, several laboratory analyses are performed, including the proximate and the elemental analysis, the coal-petrographical examination and the mineralogical analysis of all samples. During these laboratory analyses are determined the moisture, the ash, the content of volatile components and the content of C, H, N and S of lignite and lignite combustion products the permanent carbon, the calorific value and the reflectivity of lignite. The contents of trace elements in lignite, in fly ash and in bottom ash are determined using an ELAN 6100 Perkin Elmer ® instrument. The elements, which were identified, are Ag, As, B, Ba, Be, Co, Cr, Cu, Fe, Ga, Hf, Hg, Li, Mn, Mo, Ni, Pb, Sr, U, V and Zn. According to the trace elements contents of lignite and its combustion products, the mobility during combustion was determined using the Enrichment Factor (RE). Very low rate of enrichment and thus, strong volatility, have the elements As, Cd, Mo, Pb and Sr. Medium volatility is being observed in the elements Ag, B, Cr, Ni, U, V, Zn, while all the rest have low volatility due to their existence in the part of the lignite co-products that remain in the ash of the Thermal Power Plants. Furthermore, leaching experiments under pH 5 and 8.5 conditions took place to estimate the mobility of trace elements from lignite and its by-products using the Relative Mass Leached (RML) and Leaching Intensity (Ιl). The above results, under pH 5 and 8.5 conditions, indicate as more mobile trace elements in the lignite the elements As, B, Mn, Sr, in the fly ash the elements Cr, Li, Mo and Sr, and in the bottom ash the elements Li, Mo, Sr. In order to determine the geochemical affinity and the mode of occurrence of trace elements in the samples of lignite and its combustion by-products and to describe their behavior during the leaching at different pH conditions, a statistical process of the elemental analysis results is performed. In particular, the methodology of factor analysis R-type is used in the elemental analysis results, in the leaching values of trace elements of all samples, separately for pH 5 and pH 8,5 and in the fly ash and the bottom ash minerals.