[pt] Esta tese tem por objetivo avaliar o potencial de geração de biogás, por degradação anaeróbica de resíduos sólidos urbanos em perfis de um aterro sanitário. As amostras foram obtidas a partir de perfis de sondagem compostos por materiais dispostos em épocas distintas e com diferentes idades em relação a seu estágio de decomposição. Foi elaborado protocolo específico para determinação da temperatura, pH, composição gravimétrica, distribuição granulométrica, teores de umidade, de matéria orgânica, de sólidos voláteis e de lignina nessas amostras e criada metodologia com o uso de dados topográficos, para a determinação das idades de disposição dos resíduos. Foi ainda desenvolvido equipamento eudiométrico para a determinação potencial bioquímico de metano, com medidas de variação volumétrica e avaliação do prognóstico de geração de metano por modelos de primeira ordem mais consagrados (LandGEM e IPCC). Os dados experimentais indicaram que poucas propriedades apresentaram uma correlação com o perfil e com a idade dos RSU, devido à alta heterogenidade do material. Embora o potencial de biogás e a idade dos RSU não tenham apresentado correlação entre si, o material mais novo, de quase um ano, produziu maior quantidade de biogás e houve uma redução de 78 porcento dessa produção para a do material de 3 anos. Verificou-se uma relação entre o teor de matéria orgânica e de sólidos voláteis com a produção de biogás para materiais com até 4 anos. O prognóstico da geração de biogás aplicando os dados experimentais aos modelos EPA e IPCC foi menor do que quando adotados os parâmetros default. A retroanálise segundo o IPCC, com os dados experimentais, indicaram valores de DOC muito inferiores aos usados com default, resultando em menores emissões de biogás. / [en] The aim of this thesis is to evaluate of the potential biogas generation formed in the anaerobic phase from the degradation of urban solid waste with variables ages of deposition in a sanitary landfill. The materials were obtained from borehole profiles, being composed of materials disposed at different times and with variables ages in relation to their state of deposition. The knowledge of the physic-chemical characteristics is essential for assessing the biochemical potential of gases. Thus, it was developed: (i) a protocol for determination of properties, such as temperature, pH, gravimetric composition, particle size distribution, moisture content, organic matter content, volatile solids content, lignin content; (ii) one eudiometer device was constructed, with volume variation measurements for determining the biochemical methane potential; (iii) methodology to identify the ages of waste disposal by topography; and (iv) a methodology for predicting methane generation by well-known first order models (LandGEM and IPCC). Due to the high heterogeneity of the material, the experimental data indicated that few properties showed a trend in their behavior with respect to the profile and the age of MSW. Although the potential for biogas generation and the age of MSW showed no correlation, the newer material (almost one year old) showed higher biogas production. Gas production related to the 3 year old material was 78 percent lower compared to the newer one. Even with limited data, there is a relationship between the content of organic matter and/or volatile solid matter with the production of biogas for materials with more than 4 years. The prediction of biogas generation by applying experimental data was lower compared to the results applying EPA and IPCC models. The backcalculation analysis with the experimental data determined of IPCC indicated much lower DOC values than those used with the default, resulting in lower emission of biogas.

[pt] Esta tese tem como objetivo encorajar o desenvolvimento da tecnologia híbrida de lixo-energia e sua aplicação em países com acesso a reservas de gás natural, tal como o Brasil. O método consiste em avaliá-la por meio de uma análise integrada de indicadores de desempenho energético, exergético, econômico e ambiental. A tecnologia inclui dois ciclos integrados: um ciclo superior e um inferior que interagem por meio de uma caldeira de recuperação. O lixo urbano não reciclável, in natura, alimenta o ciclo inferior na caldeira de lixo enquanto o gás natural alimenta o ciclo superior na turbina a gás. O objetivo da modelagem destes sistemas consiste em propor um layout de máxima eficiência aliado a um custo acessível de produção de eletricidade/tratamento do lixo, o que é atingido com um design otimizado. O desempenho termodinâmico mais eficiente é proporcional ao percentual de gás natural, isto é, quanto maior a quantidade de lixo em relação ao gás, menos eficiente é a planta, uma vez que o lixo tem menor poder calorífico. Portanto, o desafio é buscar uma maior eficiência com maior percentual de lixo, aliando também o aspecto custo. De uma forma geral, dois cenários coexistem no mundo atual, o dos países desenvolvidos e o dos países em desenvolvimento. Os primeiros possuem inúmeras aplicações de usinas não híbridas, poucas reservas próprias de gás natural e enfrentam redução na produção de lixo, causando a sub-utilização dos sistemas. Esta tese traz uma análise completa de potenciais alternativas para re-potenciamento de plantas sub-utilizadas, demonstrando o quão pior é o seu desempenho em comparação com o ciclo otimizado. Nos países em desenvolvimento ocorre o inverso: há crescente geração de resíduos, reservas pouco exploradas de gás natural e nenhuma usina lixo-energia. Portanto, existe um grande potencial para implantação de usinas híbridas, as quais, conforme a tese demonstra, são uma alternativa muito mais razoável do que implantar usinas convencionais não híbridas. / [en] This thesis aims to foster the development of hybrid waste-energy technology and its application in countries with access to natural gas reserves, such as Brazil. The method consists of evaluating it through an integrated analysis of energy, exergy, economic and environmental indicators. The investigated system consists of a topping and a bottoming cycle integrated through a heat recovery boiler. Raw non-recyclable urban waste feeds the waste boiler while natural gas feeds a gas turbine. The goal is to propose a cycle with high efficiency able to generate electricity/treat waste within affordable costs, which is achieved with an optimized design. The cycle s performance is proportional to the share of natural gas thermal input, that is, the greater the amount of waste the lower the efficiency (waste has lower calorific value). Therefore, the challenge is to seek greater efficiency with higher percentage of waste, including also the cost aspect. In general, there are two scenarios in the world: developed and developing countries. The former has several non-hybrid plants, few natural gas reserves and face reduced waste production, causing underutilization of the existing systems. This thesis provides a complete analysis of potential alternatives for re-potentiation of underutilized plants, demonstrating how worse their performance is compared to the optimized cycle. On the other hand, developing countries present increasing waste generation, under exploited reserves of natural gas and zero waste-to-energy plants. Therefore, there is a great potential for building hybrid waste-to-energy systems, which this work demonstrates are a much more reasonable alternative than nonhybrid conventional waste-to-energy plants.

Det pågår en ökande trend i världen där fler flyttar in i tätorter. Det påverkar tätorterna i många dimensioner och en av dessa är den kommunala avfallshanteringen. När fler flyttar in mot städerna så blir det en påtryckning på befintlig hantering och är den dessutom bristfällig blir situation snabbt försämrad. Avfallshanteringen är ett känsligt område då det kan påverka människors hälsa och välmående. I utvecklingsländer är det allt för vanligt att lägga sitt avfall på öppna deponier eller låta avfallet ligga kvar längs gatorna. Detta avger farliga bakterier som ger smittsamma sjukdomar samt att tungmetaller tar sig ner i grundvattnet. FN förutspår att ungefär hälften av Afrikas befolkning kommer bo i tätorter till 2030. Denna studie handlar om avfallshanteringen i Burundi. Burundi är ett av Afrikas mest tätbefolkade länder och majoriteten lever i extrem fattigdom. Studien undersöker möjligheten för den största staden, Bujumbura, att energi återvinna sitt kommunala avfall i ett kraftvärmeverk. Det skulle vara en lösning på avfallsproblematiken samt generera el till staden. Bujumbura har idag (2022) en nästintill obefintlig avfallshantering och detta skulle vara en gynnsam lösning. I Bujumbura slängs approximativt 450 tusen ton avfall vilket har ett energiinnehåll på 5,3 PJ. Studien visar att potential för ett kraftvärmeverk med effekt på cirka 150 MW som kan omvandlas till 0,4 TWh el. Syftet med studien är att undersöka om Bujumbura kan förbättra sin avfallshantering och om det skulle vara möjligt för staden att förbränna sitt avfall i ett kraftvärmeverk. För att få underlag till vår studie har vi gjort en litteraturstudie, haft möten med berörda chefer i Bujumbura samt studiebesök på deponi och ställverk i Bujumbura. Resultatet visar att det finns möjligheter för Bujumbura att etablera ett kraftvärmeverk. För att detta ska kunna ske måste kommunen göra en omfattande satsning på hantering av avfall. / There is an ongoing trend in the world where more people are moving to urban areas. It affects in several dimensions and one of which is the municipal solid waste management. When more people move to the cities, there is a pressure on existing management and if also deficient, the situation quickly deteriorates. Waste management is a sensitive subject because it can affect people’s health and their wellbeing. In developing countries, it is common to put waste in open-air landfills. This releases dangerous bacteria that causes infectious diseases and heavy metals get into the groundwater. UN predicts that about half of Africa´s population will live in urban areas by 2030. The aim of this study is to minimize the environmental impact of municipal solid waste by establishing a combined heat and power plant in Bujumbura, Burundi, to generate electricity and heat from municipal solid waste for the city of Bujumbura as a solution to waste management challenges. Annually 450-thousand-ton waste with energy value of 5,3 PJ lays on open-air landfills. The study shows the potential for a power plant with a capacity of 150 MW. The CHP plant could generate approximately 0,4 TWh of electricity annually. This will reduce the development of unsorted waste that is otherwise dumped in open landfills. The electricity produced will be sold to the power grid to generate revenue. Furthermore, it will improve the management of solid waste and other departments who work for the development of sustainable environmental management for Bujumbura. For our study we have done a literature study, had meetings with relevant managers in Bujumbura and study visits to landfills and switchgears in Bujumbura. The results show that there are opportunities for Bujumbura to establish a combined heat and power plant. For this to happen, the municipality must make a comprehensive investment in waste management.

Tesis por compendio / [ES] El modelo M-GRCT, principal producto desarrollado en esta investigación, tiene por objeto promover mejores prácticas ambientales de gestión de residuos sólidos aprovechables en contextos municipales desfavorecidos (municipalidades de economía deprimida). Se trata de un importante instrumento técnico que brinda soporte a la gestión de residuos municipales con un enfoque de promoción de la economía circular. M-GRCT esta soportado en una herramienta ofimática dinámica que se ha programado para calcular variables de dos grandes módulos en escenarios predefinidos de simulación, con el objetivo de evaluar su eficiencia comparando el modelo tradicional de gestión de residuos reciclables (lineal) y el promocionado (circular). Los dos módulos principales del modelo corresponden a un módulo de evaluación ambiental y otro de evaluación financiera. En el módulo ambiental se calculan entre otras variables, los beneficios por reducción de huella de carbono que se logran al minimizar volúmenes de residuos aprovechables transportados y dispuestos en vertederos, o el censo de recuperadores/recicladores de oficio para promover su importante labor en la cadena de gestión de residuos, diseño de rutas selectivas y promoción de empleo. En el módulo financiero, se calculan las variables económicas a partir de la cuantificación de residuos aprovechables producidos en las municipalidades de interés, considerándolos como unidad de negocio asociada a la correcta separación que deben realizar todos los sectores de generación tipificados. Se realizan así, estimaciones de ingresos, costes e inversiones para la implementación de plantas de aprovechamiento de residuos, a partir de flujos de caja con un horizonte de evaluación predefinido y consideraciones de financiación. Como ejemplos de aplicación, M-GRCT se ha utilizado para simular la gestión de residuos aprovechables en un conjunto de municipios de economía deprimida en Colombia. Las características socioeconómicas de estos territorios, los informes oficiales asociados a la gestión de sus residuos y otros criterios base, permitieron la selección de estos. Los resultados logrados, exponen interesantes contrastes y cifras asociadas a los potenciales beneficios ambientales y económicos que se pueden lograr con la implementación real del modelo. / [CA] El model M-GRCT, principal producte desenvolupat en aquesta investigació, té per objecte promoure millors pràctiques ambientals de gestió de residus sòlids aprofitables en contextos municipals desafavorits (municipalitats d'economia deprimida). Es tracta d'un important instrument tècnic que brinda suport a la gestió de residus municipals amb un enfocament de promoció de l'economia circular. M-GRCT està suportat en una eina ofimàtica dinàmica que s'ha programat per calcular variables de dos grans mòduls en escenaris predefinits de simulació, amb l'objectiu d'avaluar-ne l'eficiència comparant el model tradicional de gestió de residus reciclables (lineal) i el promocionat (circular). Els dos mòduls principals del model corresponen a un mòdul d'avaluació ambiental i un altre d'avaluació financera. Al mòdul ambiental es calculen entre altres variables, els beneficis per reducció d'empremta de carboni que s'aconsegueixen en minimitzar volums de residus aprofitables transportats i disposats en abocadors, o el cens de recuperadors/recicladors d'ofici per promoure'n l'important labor a la cadena de gestió de residus, disseny de rutes selectives i promoció d'ocupació. Al mòdul financer, es calculen les variables econòmiques a partir de la quantificació de residus aprofitables produïts a les municipalitats d'interès, considerant-los com a unitat de negoci associada a la correcta separació que han de realitzar tots els sectors de generació tipificats. Es fan així, estimacions d'ingressos, costos i inversions per a la implementació de plantes d'aprofitament de residus, a partir de fluxos de caixa amb un horitzó d'avaluació predefinit i consideracions de finançament. Com a exemples d'aplicació, M-GRCT s'ha utilitzat per simular la gestió de residus aprofitables en un conjunt de municipis d'economia deprimida a Colòmbia. Les característiques socioeconòmiques d'aquests territoris, els informes oficials associats a la gestió dels seus residus i altres criteris base, van permetre'n la selecció. Els resultats aconseguits exposen interessants contrastos i xifres associades als potencials beneficis ambientals i econòmics que es poden aconseguir amb la implementació real del model. / [EN] The M-GRCT model, main product developed in this research, aims to promote better environmental practices for the management of usable solid waste in disadvantaged municipal contexts (municipalities with depressed economies). It is an important technical instrument that provides support for municipal waste management with a focus on promoting the circular economy. M-GRCT is supported by a dynamic office automation tool that has been programmed to calculate variables of two large modules in predefined simulation scenarios, with the aim of evaluating its efficiency by comparing the traditional recyclable waste management model (linear) and the promoted-do (circular). The two main modules of the model correspond to an environmental assessment module and a financial assessment module. The environmental module calculates, among other variables, the benefits of reducing the carbon footprint achieved by minimizing volumes of usable waste transported and disposed of in landfills, or the census of collectors/recyclers by trade to promote its important work in the waste management chain, design of selective routes and employment promotion. In the financial module, the economic variables are calculated based on the quantification of usable waste produced in the municipalities of interest, considering them as a business unit associated with the correct separation that all typified generation sectors must carry out. Thus, estimates of income, costs and investments are made for the implementation of waste utilization plants, based on cash flows with a predefined evaluation horizon and financing considerations. As application examples, M-GRCT has been used to simulate the management of usable waste in a group of municipalities with depressed economies in Colombia. The socioeconomic characteristics of these territories, the official reports associated with their waste management and other basic criteria, allowed their selection. The results achieved expose interesting contrasts and figures associated with the potential environmental and economic benefits that can be achieved with the real implementation of the model. / Vargas Terranova, CA. (2022). Desarrollo de un modelo de economía circular para la gestión de residuos sólidos. Aplicación en municipios de economía deprimida en Colombia [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/191028 / Compendio

El presente articulo tiene como objetivo revisar producciones científicas vinculado con el manejo de residuos sólidos en gobiernos regionales, provinciales y de distritales; la metodología de tipo y diseño cuantitativo comprendió procesos exploratorios y descriptivos; el uso de métodos teóricos; y, como muestra se tomó 10 artículos confiables y originales lo cual fueron publicados entre los años 2016 y 2023. Para el análisis y procesamiento de datos se utilizó la técnica que corresponde a un análisis documental y como instrumento una matriz lógica. Los resultados de dicho artículo manifiestan que la mayoría de las investigaciones científicas están relacionados en la gestión, manejo y mitigación de los residuos sólidos municipales; con propuestas de modelos sistémicos innovadores, políticas públicas y tecnologías perdurables ; y con respecto a las conclusiones de mayor importancia quecomprenden una evaluación diagnóstica en la cual se concluye el escaso e insuficiente conocimiento sobre el mal manejo de los residuos sólidos municipales en cada gobierno local , asimismo, lo cual se conocen lineamientos teóricos prácticos para minimizar la contaminación del medio ambiente sobre el entorno de los gobiernos regionales, provinciales y distritales para garantizar la sostenibilidad ambiental, mejor calidad económica, y mejorcalidad de vida. / The objective of this article is to review scientific productions linked to solid waste management in regional, provincial and district governments; The quantitative type and design methodology included exploratory and descriptive processes; the use of theoretical methods; and, as a sample, 10 reliable and original articles were taken, which were published between the years 2016 and 2023. For the analysis and processing of data, the technique that corresponds to a documentary analysis and a logical matrix as an instrument was used. The results of said article show that the majority of scientific research is related to the management, handling and mitigation of municipal solid waste; with proposals for innovative systemic models, public policies and lasting technologies; and with respect to the most important conclusions that include a diagnostic evaluation in which the scarce and insufficient knowledge about the poor management of municipal solid waste in each local government is concluded, likewise, which theoretical and practical guidelines are known to minimize the environmental pollution on the surroundings of regional, provincial and district governments to guarantee environmental sustainability, better economic quality, and better quality of life.

The objective of this thesis is to evaluate the engineering properties of Municipal Solid Waste (MSW) that are necessary in the design of landfills. The engineering properties of MSW such as compressibility, shear strength, stiffness and hydraulic conductivity are crucial in design and construction of landfills. The variation of the engineering properties with time, age and degradation are of paramount importance in the field of landfill engineering. There is a need to address the role of the engineering properties in landfill engineering as it is not apparent how the engineering characteristics vary with time. The thesis presents the results of study of the engineering properties of MSW comprehensively and develops experimental data for design of MSW landfills. The work includes the study of the index properties and the engineering properties of MSW such as compressibility, shear strength, shear modulus and damping ratio and a detailed experimental study of the bioreactor landfill. The components of settlements, variation of shear strength with respect to unit weight and particle size are determined experimentally and analyzed. The dynamic properties such as shear modulus and material damping ratio and its variation with parameters such as unit weight, load, amplitude, degradation and moisture content are studied and analyzed. The normalized shear modulus reduction curve which is used in the seismic analysis of the landfills is developed for MSW based on the experimental results and previous studies. A pilot-scale bioreactor was setup in the laboratory for long term monitoring of the settlement, temperature variation and gas production simultaneously. The parameters of interest viz, pH, BOD, COD, conductivity, alkalinity, methane and carbon-di-oxide were determined. The generated data can be effectively used in the engineered design of landfills. For a better understanding, the present thesis is divided into the following eight chapter Chapter 1 provides a general introduction to the thesis with respect to the importance of engineering properties of MSW and presents the organization of the thesis. Chapter 2 presents a detailed review of literature pertaining to the basic, index and the engineering properties of MSW namely compressibility, shear strength, shear modulus and damping ratio, bioreactor landfill and also the scope of the study. Chapter 3 includes the materials and methods followed in the thesis. Chapter 4 presents the evaluation of compressibility characteristics of MSW including the components of settlement and the settlement model parameters. Chapter 5 presents the determination of the shear strength properties of MSW using direct shear tests and triaxial tests. The variation of the strength with respect to unit weight and the particle size is examined. The results are examined in terms of strength ratio and stiffness ratio and the implications are discussed. Chapter 6 presents the study of the dynamic characters of MSW. The variation of the shear modulus and damping ratio with respect to unit weight, confining pressure, loading frequency, decomposition and moisture content are analyzed. Normalized shear modulus reduction and damping curves are proposed for seismic analysis. Chapter 7 presents the study of the conventional and the bioreactor landfill in a small scale laboratory setup. A large scale experimental setup is fabricated to study the characteristics of a bioreactor landfill and includes the long term monitoring and analysis of temperature, gas, settlement and leachate characteristics periodically. The results of the comprehensive study are presented in this chapter. Chapter 8 summarizes the important conclusions from the various experimental studies reported in this dissertation. Conclusions and the scope of future work are presented. A detailed list of references and the list of publications from the thesis are presented at the end. Appendix A presents the life cycle analysis and life cycle cost analysis of MSW land disposal options. The land disposal options such as open dumps, engineered landfills and bioreactor landfills are analyzed in this study.

Les procédés anaérobies de traitement de déchets apparaissent clairement pouvoir répondre à l'enjeu socio-économique actuel que représente la valorisation énergétique de la fraction organique contenue dans les déchets ménagers. En effet, les processus de dégradation anaérobies font intervenir en cascade, différentes réactions et populations de micro-organismes permettant de transformer la matière organique en biogaz riche en méthane. Une bonne connaissance des effets des paramètres opérationnels sur l'orientation des métabolismes s'avère ainsi nécessaire à l'émergence de solutions permettant d'optimiser ces procédés. Ceci est notamment le cas pour la dernière étape, appelée méthanogenèse. Dans ce contexte, l'approche isotopique reposant sur la mesure de la composition isotopique (13C/12C) du méthane et du dioxyde de carbone, devrait pouvoir répondre à cet objectif en permettant l'identification des métabolismes à l'origine de la production du méthane. La transposabilité à l'étude de la digestion anaérobie des déchets de cette approche isotopique déjà utilisée dans les écosystèmes naturels, a tout d'abord été vérifiée expérimentalement. Les effets de certains paramètres opérationnels connus pour avoir un impact fort sur le processus de digestion anaérobie, tels que la température et la concentration en azote ammoniacal, ont ensuite été étudiés. Il a été mis en évidence qu'en condition thermophile, la méthanogenèse acétoclaste observée en condition mésophile, était remplacée par une oxydation syntrophique de l'acétate lors de la digestion anaérobie des déchets ménagers. Des expériences sur acétate ont montré que cet effet sur les voies métaboliques n'était toutefois pas systématique et pourrait ne pas être dû à un effet direct d'une augmentation de la température, mais plutôt à l'accroissement de la concentration en ammoniaque qui en résulte. D'autres expériences ont clairement établi qu'une augmentation de la concentration en azote ammoniacal conduisait également à la mise en place de l'oxydation syntrophique de l'acétate. Le couplage de l'approche isotopique avec des analyses microbiologiques a révélé que cette réaction d'oxydation syntrophique de l'acétate, à haute concentration en azote ammoniacal, pouvait s'établir telle que déjà décrite, par la mise en place d'une relation symbiotique bactéries/archées hydrogénotrophes strictes, mais également de manière différente en impliquant des membres de la famille Methanosarcinaceae qui pourraient réaliser seuls les deux étapes de la réaction (oxydation et méthanogenèse hydrogénotrophe). L'application de l'approche isotopique a également permis de mettre en évidence, lors d'une expérience visant à simuler la recirculation de différents effluents au sein d'une installation de stockage de déchets bioactive, l'influence de la nature de l'effluent sur l'orientation des métabolismes méthanogènes. Enfin, l'influence de la proportion de déchets verts, lors de la co-digestion biodéchets / déchets verts, sur la concentration en ions ammonium libérés ainsi que sur l'orientation du métabolisme en résultant, a été étudiée. Les potentialités d'une utilisation de l'approche isotopique sur site ont également été investiguées au travers d'une campagne de mesures sur une installation de stockage de déchets non dangereux. / Anaerobic waste treatment processes are clearly part of the answer to a current important socio-economic issue in waste management: energy production from the organic fraction of municipal solid waste. The anaerobic digestion of municipal solid waste is a complex process involving numerous reactions and microorganism communities. At the end of the degradation process, some biogas with a particularly high methane content is produced. A detailed knowledge on how operational parameters affect metabolism orientations is required to optimize these treatment processes. This is in particular the case for the last degradation reaction called methanogenesis. In this context, an isotopic approach based on isotopic composition measurements (13C/12C) for methane and carbon dioxide can provide some clues with regard to this objective. Indeed, this methodology enables the determination of the methanogenic pathways by which methane is produced.Transferability of the isotopic approach used for natural ecosystems to the field of anaerobic digestion of municipal solid waste was first experimentally verified. In a second time, the effects of some operational parameters known to strongly impact the anaerobic digestion process, such as temperature and ammonia concentration, were studied. During anaerobic digestion of reconstituted municipal solid waste in thermophilic conditions, it was shown that aceticlastic methanogenesis (occurring in mesophilic conditions) was replaced by a syntrophic acetate oxidation reaction. Additional experiments using acetate as sole substrate were performed and showed that this effect on the metabolic pathways was not systematic. Consequently, it cannot be due to a direct effect of the temperature increase. It could rather be explained by the induced and indirect increase in ammonia concentration. Additional experiments clearly demonstrated that an increase in ammonia concentration led to the establishment of a syntrophic acetate oxidation reaction. The isotopic approach was combined with microbiological analyses and showed that the syntrophic acetate oxidation reaction occurring at high ammonia concentration during acetate incubations could have been performed through a syntrophic relationship between bacteria and strict hydrogenotrophic archaea, as previously described in the literature. Interestingly, the syntrophic acetate oxidation could also have occurred using a different pathway relying on members of the Methanosarcinaceae family putatively able to perform the two steps of the reaction (oxidation and hydrogenotrophic methanogenesis). In addition, the implementation of the isotopic approach during an experiment designed to simulate a landfill bioreactor evidenced the influence of the effluent's nature on the methanogenesis metabolism orientation. The influence of green waste proportion during the co-digestion of biowaste / green waste mixtures on resulting ammonia concentrations and methanogenesis pathways was also studied through dedicated experiments. Finally, the potential of the isotopic approach for landfill-scale application was investigated through a measurement campaign on a landfill site.

Efficient waste management enables the protection of human health, reducing environmental pollution, saving of natural resources, and achieving sustainable and profitable management of energy. In many countries, the general guidelines for waste management are set by national or local waste management plans. Various models provide local authorities with decision-making tools in planning long-term waste management scenarios.This study aims at providing a special model framework for the evaluation of ecological–economic efficiency (ECO-EE) of waste management. This will serve as an information support tool for decision making by actors of a solid waste management (SWM) scheme, primarily at the municipal and regional levels. The objective of this study is to apply the waste management’s efficient decision (WAMED) model along with the company statistical business tool for environmental recovery indicator (COSTBUSTER) model to SWM and municipal solid waste (MSW) schemes in general in order to evaluate and improve their ECO-EE. COSTBUSTER is a mathematical indicator for the size and extent of implementation costs of a certain SWM scheme, compared with the total size of the average financial budget of a SWM actor of a certain kind. In particular, WAMED is proposed for evaluating the suitability to invest in baling technology. Baling of solid waste is an emerging technology which is extensively used worldwide to temporarily store waste for either incineration or recovery of raw materials. The model for efficient use of resources for optimal production economy (the EUROPE model) is for the first time applied to emissions from baling facilities. It has been analysed how cost-benefit analysis (CBA) and full cost accounting (FCA) can facilitate environmental optimisation of SWM schemes. The effort in this work represents a continuation of such ambitions as an enlargement of the research area of CBA based modelling within SWM. In the thesis, certain theoretical and economic aspects of SWM were analysed as case studies. A shift of viewpoints within the field of waste management is presented. This shift is in accordance with the prevailing concept of sustainable development, as commonly understood. It is concluded that in the practical SWM context, the findings of the study point at the possibilities to modify the common CBA- and FCA-based methods by WAMED, COSTBUSTER, and EUROPE. Therefore, it can be said that estimations in a SWM scheme can be carried out by using certain economic model, if properly modified in a logical and plausible way. New principles for cost allocation to SWM residual products are presented in the current work. They imply strong industrial cost saving incentives through promoting the introduction of new and improved processing technologies for rest-waste. Such incentives then strongly promote investments that are likely to improve both the environment and the corporate profitability. Thereby, the occurrence of non-commercialised, and hence not utilized, wastes is reduced. This improves the short term corporate economy through saving raw materials such as solid waste fuel, spending less time for administrating waste flows, and less wear and tear of the plant machinery. Additional environmental advantages which affect the balance sheets in a favourable way are related to the long-term business economy and extended environmental goodwill. This is due to the recently introduced way of considering solid waste as regular goods in financial terms - the equality principle. If waste is seen as goods, and not wasted in landfills, the environment will improve. This, in turn, leads to an improved quality of life. Based on the current study, it is recommended to apply WAMED to SWM schemes in order to evaluate their ECO–EE to justify decision making and investments. Also, it is recommended to apply COSTBUSTER, based on the current WAMED outcome, to SWM schemes to determine their relative size and extent. It is recommended to apply EUROPE to the emissions in case of accidental burning, treatment of leachate, andabatement with odours at any SWM scheme, based on the induced economic incentives, in order to reduce unwanted substances and phenomena.

[pt] A gestão dos Resíduos Sólidos Urbanos (RSU) e seu consequente reaproveitamento ou não é um problema existente no Brasil e no mundo. No Brasil, a produção de energia mediante incineração de RSU ainda está na sua etapa inicial, como por exemplo, com a implantação da Usina Verde no campus da UFRJ, com a consequente produção de subprodutos, como as cinzas volante e de fundo. Este estudo apresenta o comportamento de um solo coluvionar argiloso estabilizado com cinzas de RSU sob carregamento estático, tendo como principal objetivo avaliar a influência destas cinzas misturadas com o solo para possíveis aplicações em obras geotécnicas. Para isso foram realizados ensaios de caracterização física, química e mecânica, como ensaios de compactação Proctor Normal e ensaios triaxiais consolidados isotropicamente drenados (CID), para o solo puro e misturas solo-cinza. Foram avaliadas as influências do teor de cinzas (20 por cento, 30 por cento e 40 por cento de cinza volante e de cinza de fundo), bem como do tempo de cura (30 e 60 dias). Os resultados mostram que todas as misturas solo-cinza apresentam melhores parâmetros de resistência, em comparação do solo puro, onde as misturas solo-cinza volante apresentaram melhores resultados quando comparadas às misturas solo-cinza de fundo. A variação de teor de cinza adicionado ao solo, sem cura, mostra que para maiores teores de cinza volante a coesão diminui e ocorre o contrário com a cinza de fundo. Com relação ao tempo de cura, na maioria dos casos houve melhora do comportamento das misturas solo-cinza em comparação ao obtido sem cura. O teor de cinza (volante ou de fundo), tempo de cura e a tensão de confinamento influenciam na deformação volumétrica das misturas solo-cinza, apresentando menores deformações volumétricas para maiores teores de cinza e maiores tempos de cura. As misturas com 40 por cento de cinza volante e 30 por cento de cinza de fundo apresentaram as melhores características de resistência e poderiam ser utilizadas como estabilizante no solo estudado, cumprindo exigências geotécnicas e ambientais, além de rebaixar os custos de obra e dar um destino mais nobre para as cinzas de RSU. / [en] Management of Municipal Solid Waste (MSW) and its subsequent reuse or not is an existing problem in Brazil and the world. In Brazil, the production of energy through incineration of MSW is still in its initial stage, for example, with the implementation of Usina Verde on campus at UFRJ, with the consequent production of byproducts, such as fly and bottom ashes. This study presents the behavior of a colluvial clayey soil stabilized with ashes from MSW under static load, with the main objective to evaluate the influence of these ashes mixed with the soil for possible applications in geotechnical works. For this characterization were performed physical, chemical and mechanical tests, as Proctor compaction tests Normal isotropically consolidated and drained triaxial (CID) for the pure and soil-ash mixtures. Were evaluated the influence of the ash content (20 per cent, 30 per cent and 40 per cent fly ash and botton ash) and of curing time (30 and 60 days). The results show that all mixtures soil-ash have better shear strength compared to the pure soil, where the soil- fly ash mixtures showed better results compared to mixtures of soil- bottom ash. The variation of the ash content added to the soil, without curing, shows that higher levels of ash the cohesion decrease and the opposite occurs with the bottom ash. Respect to the curing time, in most cases there was as improvement of the behavior of mixtures soil-ash compared to that obtained without curing. The ash content (fly or bottom), curing time and confinement stress influence the volumetric deformation to soil-ash mixtures, showed lower volumetric deformations to higher concentrations of ash and longer curing times. The mixtures with 40 per cent fly ash and 30 per cent bottom ash, showed the best characteristics of strength and could be used as stabilizer in the studied soil, compliance requirements geotechnical and environmental, in addition to lower labor costs and give a nobler destiny for the ashes of MSW.

[pt] Este estudo apresenta o comportamento de um solo arenoso estabilizado com cinzas obtidas através da incineração de Resíduo Sólido Urbano (RSU) e cal. Através de um estudo experimental, objetiva-se avaliar a aplicabilidade de misturas solo-cinza e solo-cinza volante-cal em obras geotécnicas como, por exemplo, camadas de aterros sanitários, aterros sobre solos moles e estabilização de taludes. Para isso, foram realizados ensaios de caracterização física, química e mecânica (ensaios triaxiais CID) para os materiais envolvidos. Para as misturas solo-cinza volante-cal, adicionou-se 3 porcento de cal em substituição ao peso seco das cinzas. Foram avaliadas as influências do teor de cinza (30 e 40 porcento) e tipo de cinza (volante - CV e fundo - CF), bem como o tempo de cura (0, 60 e 90 dias) para misturas com cinza volante e cal. Os resultados mostram que tanto as misturas com CV, como CF, apresentam resultados satisfatórios. Para ambas as cinzas, as porcentagens de 30 e 40 porcento apresentaram resultados similares, podendo-se adotar o valor de 40 porcento como teor ótimo, uma vez que proporciona a utilização de uma maior quantidade de resíduo. Comparando-se as cinzas, a CF apresentou resultados mais satisfatórios que a CV. Para as misturas com cura, observou-se que no tempo de 60 dias o material sofreu um maior ganho de resistência. Foram utilizados dois métodos de moldagem de corpo de prova para o ensaio com cura, obtendo-se melhor resultado para o método onde a cura era realizada em um corpo de prova pré-moldado. Portanto o uso das cinzas de RSU em mistura com este tipo de solo se mostra satisfatório, uma vez que apresentou um bom comportamento, contribui com o menor consumo de material natural e proporciona uma destinação ambientalmente correta deste resíduo. / [en] This study presents the behavior of a sandy soil stabilized with municipal solid waste ash, and lime. In order to evaluate the applicability of mixtures soil-ash and soil-fly ash-lime for using in geotechnical projects as layers of landfills, embankment on soft soils and slope stability, an experimental campaign is presented. Thus, physical, chemical and mechanical (isotropically consolidated-drained triaxial test) characterization tests were performed for each material and mixtures. It was used 3 percent of lime in the mixtures soil- fly ash-lime, being added in replacement to the dry weight of fly ash. Were evaluated the influence of ash content (30 and 40 percent), type of ash (fly ash and bottom ash) and curing time (0, 60 and 90 days) for mixtures containing fly ash and lime. The results have shown that mixtures with both kinds of ashes present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure material. For both kinds of ashes the variation of the content has not provided significant changes in the strength parameters, therefore, 40 percent can be considered as best content, once it provides a bigger destination of the residue. Comparing fly and bottom ash, the last has presented better results than fly ash. For mixtures with lime and cure, it has been observed better results for 60 days of cure, with greater gain of strength. Two molding methods have been used for preparing the mixture specimen, being obtained a better result with pre modeled specimen. Therefore, the use of municipal solid waste ash for stabilizing this kind of soil for using in the cited works, could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.