No description available.

[pt] Esta tese apresenta um novo modelo para a avaliação de recalques em aterros de disposição de resíduos sólidos urbanos. Trata-se de um modelo unidimensional, onde os recalques resultam da ação de duas componentes, uma mecânica e outra biológica, que permite a avaliação da evolução das variações de volume do aterro com o tempo. A componente mecânica é caracterizada por um recalque imediato, causado pela redução da macroporosidade e pela drenagem de líquidos e gases presentes na massa de resíduos no instante da disposição devido à ação das cargas aplicadas, e por uma componente de longo prazo, originada pela deformação lenta da estrutura dos resíduos. A componente biológica é resultado dos processos de decomposição que ocorrem no interior dos aterros, onde a contínua transferência de massa da fase sólida para as fases líquida e, principalmente, gasosa, causa uma redução de volume dos resíduos. Por hipótese, os parâmetros utilizados na avaliação das duas componentes não variam com tempo. O comportamento dos resíduos é analisado a partir de propriedades de suas frações constituintes, possibilitando, desta forma, a análise de situações onde ocorram variações da composição e das condições operacionais. O modelo também permite a análise de aterros com construção em etapas e realização de ensaios de carregamento. Diversos casos históricos, coletados na literatura, foram simulados. Os resultados obtidos com o modelo mostraram-se bastante semelhantes aos de campo, indicando ser válido o conjunto de hipóteses adotadas. Na análise desses casos constatou-se uma falta de padronização na apresentação ou mesmo inexistência das informações necessárias às simulações com o modelo, tornando-se indispensável a adoção de hipóteses, sendo estas fundamentadas em aspectos físicos e observacionais. O modelo mostrou-se bastante versátil, podendo ser adaptado facilmente a novos problemas, incluindo a variação dos parâmetros com o tempo. / [en] This thesis presents a new model to evaluate settlements in municipal solid waste fills. It refers to a one dimensional model in which the settlements result from two components, one due to mechanical behavior and the other from biological degradation. The mechanical component is formed by an immediate settlement, in which the load application results in a reduction of the macroporosity and drainage of liquids and gases, and by a long term settlement, associated with waste structure creep. The biological component is a result of the decomposition processes occurring within the waste mass, in which the continuous mass transference from solid phase to liquid and, mainly, to gaseous phase, that causes a waste volume reduction. It was assumed that the parameters used to evaluate both components does not vary with time. The waste behavior is analyzed from its fractions properties, allowing the analysis of problems where the composition and operational conditions change with time. The model can also consider staggered construction of the fill and the simulation of load tests.Several historical cases obtained from literature were simulated. The results of the simulations presented a good representation of the field data, validating the adopted set of hypothesis. During the analysis it was observed a lack of standardization in the way the data are presented and even an absence of data as required by the developed model. In such cases, some hypothesis were adopted based on physical and observational criteria.The developed model was shown to be versatile and can easily be adapted to new problems, including the change of properties of the waste mass with time.

No / In the search for an efficient and economical method to treat a leachate generated from a controlled municipal solid waste landfill site (Jebel Chakir) in the region of greater Tunis in Tunisia, ozone alone and ozone combined with hydrogen peroxide were studied. The leachate was characterised by high COD, low biodegradability and intense dark colour. A purpose-built reactor, to avoid foaming, was used for the study. It was found that ozone efficacy was almost doubled when combined with hydrogen peroxide at 2 g/L but higher H2O2 concentrations gave lower performances. Enhancement in the leachate biodegradability from about 0.1 to about 0.7 was achieved by the O3/H2O2 system. Insignificant changes in pH that may due to buffering effect of bicarbonate was found. A small decrease in sulphate concentrations were also observed. In contrast, chloride concentration declined at the beginning of the experiment then increased to reach its initial value. Estimates of the operating costs were made for comparison purposes and it was found that the O3/H2O2 system at 2 g/L H2O2 gave the lowest cost of about 3.1 TND (2.3 USD)/kg COD removed.

Yes / Increasing infrastructure growth has forced the construction industry to look for wasteful, cheap, and suitable materials for construction. An investigation into the geotechnical utilization of fly ash was carried out in the present study. Practical applications normally involve the use of large quantities of fly ash, so proper mixing of the fly ash with other materials may not be significantly achieved. Therefore, the present paper investigates the behaviour of a fly ash–bentonite layered system with different ratios. The physical properties and chemical composition of fly ash and bentonite were determined. SEM and energy dispersive X-ray experiments were also used to investigate the morphology and phase compositions of fly ash and bentonite. A series of consolidated undrained (CU) triaxial tests on fly ash–bentonite were carried out to investigate shear strength characteristics. Fly ash (F) and bentonite (B) were used in the following ratios: 1:1 (50% F:50% B), 2:1 (67% F:33% B), 3:1 (75% F:25% B), and 4:1 (80% F:20% B), with different numbers of interfaces (N), i.e., 1, 2, and 3 for each ratio. The deviator stress and cohesion value were found to increase with the number of interfaces for each ratio. The angle of shear resistance changed marginally with the increase in the fly ash–bentonite ratios and varying interfaces.

Anaerobic bioreactor landfills are the landfills with an increased moisture content in order to achieve a better biodegradation. Many Bioreactor landfills accept outside liquid wastes to achieve a higher moisture content . But the effect of these wastes on the degradation of landfill components is not known. In this study, the effect of sugar waste, surfactant waste and paint waste on the degradation of landfill components was investigated. Sugar waste, surfactant waste and paint wastes in different concentrations were added to the combination of paper, cardboard, office paper and plastic with a total moisture content of 70%. The samples were incubated, sampled and analytical parameters analyzed. Sugar waste having a COD of 250,000 mg/L in a concentration of even 5% of the total weight was found inhibitive due to a drop in pH and accumulation of volatile fatty acids. Reactors with surfactant concentrations ranging from 50 mg/L to 500 mg/L showed that a higher concentration of 500 mg/L or above may be inhibitive in nature and the inhibition increases with increase in the concentration of surfactant. However, paint waste with a concentration of even 7.5% highly inhibited the degradation in the reactors. This could possibly be because of some toxicity. / Master of Science

The effect of high organic liquid wastes on the overall performance of anaerobic bioreactor landfills is not known. In this study three different liquid wastes were added to mix of office paper, newspaper, cardboard and plastic in 3 different concentrations under anaerobic conditions to determine their effect on degradation of organics. The addition of buffer chemicals was found to improve degradation compared to data from an earlier study done without the addition of initial buffering. Paint waste with a COD 237,500 mg/L added at a concentration of 10% did not show any negative effect on the overall performance. The distillation waste with a COD of 812,500 mg/L added at 5% and higher concentration resulted in accumulation of volatile fatty acids and strong inhibition. The surfactant waste added at concentrations up to 1500 mg/L showed some inhibition but the overall performance was good. The surfactant waste also appeared to improve lignin degradation. / Master of Science

There are more than three thousand landfills in the United States, in which approximately 55% (1998, U. S. EPA 1999) of the MSW generated in the US is buried. The majority of the landfills are conventional, but in the last two decades new types of landfills, called leachate recycle and bioreactor landfills, have been designed and tested as an enhanced environment for biochemical degradation of municipal solid waste. All the landfills are regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA). The shortage of time and money has limited the amount of research done on waste stability analysis. The purpose of this study was to evaluate the importance of lignocelluloses in biodegradation and the secondary settlement based on dry density and typical landfill evaluating parameters. Both parts of the study samples were collected and analyzed from eleven landfills. In the first part of the study, bioreactor landfills were found more effective, faster in the degradation of VS and cellulose as compared to conventional landfills. The time required for stabilization is reduced to about 1/3 that of conventional landfills. The lignocelluloses degradation that occurs in these landfills is happening in two phases. In the initial, rapid degradation phase, the primary degradation substrate is cellulose. In the second phase, after cellulose degraded to 15-20% of the waste, degradation of the remaining cellulose along with lignin and the hemicelluloses takes place. The start of lignin and hemicellulose degradation results in an increase in the biochemical methane potential (BMP). In the second part of the study, the addition of moisture to the landfills presented a contentious issue. Moisture is encouraged for MSW refuse degradation, but for settlement it reduces compressibility. In leachate recycle landfills, the dry density is higher than in conventional landfills; therefore there is more available room for further MSW load. The increase can reach up to 40 percent in total volume. / Master of Science

No description available.

No Brasil, a Resolução CONAMA nº 307/2002 e a Resolução CONAMA nº 448/2012 definem que os resíduos da construção civil (RCC) classe A, caso não sejam reutilizados ou reciclados na forma de agregados, devem ser destinados para aterros de resíduos classe A de reservação de material para usos futuros. Porém, pequenas quantidades de resíduos de outras classes, e resíduos não inertes acabam dispostos neste tipo de aterro. Esse fato pode ser agravado devido esses aterros não possuírem impermeabilização de base e sistemas de drenagem de lixiviados, o que pode favorecer a migração desses lixiviados de RCC para reservas de água, e colocar em risco a saúde da população e o meio ambiente. Com intuito de contribuir nessa área de conhecimento o presente estudo teve por finalidade investigar o potencial de contaminação de lixiviados de aterros de resíduos da construção civil por meio de simulações em colunas de lixiviação. Para tanto, foi realizado um estudo por meio de duas etapas &#8211 simulação de lixiviação de amostras de RCC em colunas de lixiviação (saturadas e não saturadas), e coleta de água subterrânea do aterro de RCC classe A. Resultados da pesquisa apontaram que as amostras de agregados de RCC classe A foram classificadas, de acordo com a NBR 10.004 (ABNT, 2004), como sendo resíduos não perigosos e não inertes &#8211 Classe II A. A hipótese tema do estudo foi verificada, a qual apontou que existe potencial de contaminação dos lixiviados gerados em aterros de RCC Classe A, os quais podem vir a poluir ou contaminar o solo e as águas subterrâneas inviabilizando o uso dessas águas para consumo humano. As concentrações máximas dos lixiviados de RCC que excederam o valor máximo permitido para consumo humano nas simulações foram: sulfato (950 mg/L), dureza (11.280 mg/L), cor (124 uH), Pb (0,36 mg/L), Cd (0,075 mg/L), Ni (0,088 mg/L), Fe (0,658 mg/L), Ba (1,205 mg/L), Cr (0,125 mg/L), Mn (0,297 mg/L), e Al (3,44 mg/L). A pesquisa também contribuiu para melhoria de projetos, execução e controle de aterros de resíduos da construção civil, a fim de futuramente equacionar possíveis impactos negativos gerados por esse tipo de resíduo ao solo e recursos hídricos. / In Brazil, the resolutions nº 307/2002 and nº 448/2012 of the National Environmental Council (CONAMA) define that the construction and demolition (C&D) class A - reusable or recyclable wastes as aggregates, such as ceramic components, grout and concrete -, if not reused or recycled as aggregates, should be going to C&D wastes landfill. These wastes must be disposed in the soil for the reservation of segregated materials for future use or future use of the area. However, these landfills receive small quantities of wastes from other sources and non-inert wastes. This fact can be aggravated because the C&D wastes are disposed in these unlined landfills and without drains of leachate. In this context, the C&D wastes leachate may migrate to water supplies causing risks to both human health and the environment. In an attempt to contribute to this area of knowledge, this project aims to investigate the pollution potential of leachate of construction and demolition wastes landfills in lysimeters. A survey will be conducted in two stages &#8211 simulation of leachate samples of C&D wastes lysimeters (saturated and unsaturated), and study of the C&D wastes landfill of the city through the collection of groundwater. Results of the research classified, for metals, the samples of aggregates of C&D wastes class A &#8211 such as ceramic components (bricks, blocks), grout and concrete &#8211 as non-hazardous and non-inert. The pollution of leachate of C&D wastes landfills was observed. The presence of these contaminants could affect the use of this water for human consumption. The parameters that exceeded the maximum value for human consumption were: sulfate (950 mg/L), hardness (11,280 mg/L), color (124 uH), Pb (0.36 mg/L), Cd (0.075 mg/L), Ni (0.088 mg/L), Fe (0.658 mg/L), Ba (1,205 mg/L) Cr (0.125 mg/L) Mn (0,297 mg/L), and Al (3.44 mg/L ).The research identified requirements for improvement projects, execution and control of C&D wastes landfills to minimize future potential adverse impacts generated by these residues in water resources.

A high level of plant mortality on the Bisasar Road landfill, Durban, South Africa initiated an investigation into the primary causes of the mortalities and a search for potentially tolerant plant species. Field studies revealed that volunteer grass growth on cover soils was primarily limited by elevated soil C02, with high soil conductivity and low soil moisture possibly compounding the effect. Cynodon dactylon, the most abundant coloniser of the site appeared to be relatively sensitive to high soil CO2, whilst less common species such as Sporobolis cifricanus and Paspalum Paspoloides appeared to be less sensitive. Further research focused on the high mortality of trees planted on the landfill providing insight into the important variables limiting survival· and the relative differences in performance of 20 tree species. A more rigorous 14-month field experiment was designed and constructed, to assess the performance of 10 of the more promising tree species, the environmental conditions limiting tree growth and the benefit of a deeper layer of better quality topsoil. Some species, such as Barringtonia racemosa, performed relatively well in the field experiment, whilst other species such as Syzygium cordatum, and Harpephyllum caffrom experienced high mortalities and poor growth. The better quality topsoil layer provided little improvement in the performance of the stronger or the weaker species, however significant improvements were recorded for species with relatively intermediate performance. The composition of the soil atmosphere was shown to determine rooting depth. Species that performed better had deeper roots, possibly assisting them in utilising deeper soil moisture reserves. It was concluded that high soil CO2 and low soil O2 levels were the key variables responsible for poor tree survival and growth in this field experiment. A soil fumigation system was designed to provide more control of soil gas concentrations and to experimentally investigate differential species responses and the relative effects of soil CO2 and O2 on tree survival and growth. The apparatus fumigated, for a period of 140 days, the rhizosphere of 80 potted 'tolerant' (Barringtonia racemosa) and 'non tolerant' (Harpephyllum caffrum) trees with 4 treatments consisting of varying combinations of CO2 and 02. The difference in performance of Barringtonia racemosa and Harpephyllum caffrum in the experiment on the landfill was similar to that of the elevated CO2 low O2 fumigation treatment, supporting the premise that landfill gas was the key cause for poor performance of plants. Reduced stomatal conductance and resultant limitations on photosynthesis were found to be indicative of species sensitivity. Low O2 had an additive effect on the impact of elevated CO2 in Harpephyllum caffrum however, even with normal soil O2 levels, 25% soil CO2 had negative growth effects on this sensitive species. Maintenance of plant health and better performance of Barringtonia was attributed to a high inherent level of tissue porosity and aerenchyma. The research provided a greater understanding of the causes of poor vegetation growth and the possible mechanisms of species tolerance to landfill conditions. / Thesis (Ph.D.)-University of Natal, Durban, 2003.