José Fernando Thomé Jucá

Objective: To propose a governance model for the closure of tailings dams, structured around four criteria - Technical, Governance, Participation & Transparency, and Compliance — each composed of subcriteria detailing the critical activities required for conducting the process. Theoretical Framework: The failures of tailings dams in 2015 and 2019 led to the approval of increasingly restrictive legislation, such as Law No. 14,066/2020, which amended the National Dam Safety Policy (Law No. 12,334/2010), and the resolutions of the Agência Nacional de Mineração (ANM) No. 95/2022, 130/2023, and 175/2024. However, practical experience has shown that a closure process cannot be reduced to a legal obligation or viewed solely as a technical issue. Method: The development of the governance model was based on a bibliographic and documentary review of public policies, Brazilian dam safety legislation, ANM resolutions, and documents from various related entities, in addition to consulting international guidelines and global references for tailings dam management. All the references reviewed converge on the understanding that a closure process must be assessed from a multidimensional perspective, combining technical, governance, transparency, and regulatory compliance aspects. Results and Discussion: Despite the wide range of regulations on dam closure, Brazil still lacks a structured model that allows for the assessment of governance in closure processes in a way that is comparable to best practices and global experiences, ensuring both technical quality and social transparency. Research Implications: The proposed governance model represents an innovative tool for public managers, mining companies, regulatory agencies, and researchers, enabling a comparable and transparent evaluation of closure processes, thereby strengthening trust among the involved stakeholders. Originality/Value: The proposed model can be used as a management or audit tool, making the closure process more transparent and aligned with national and international best practices. Furthermore, it can serve as a comparative basis to monitor the evolution of governance over time or to evaluate governance performance in the closure of different dams.

Soil-atmosphere interactions comprise a multidisciplinary and transdisciplinary subject of interest to numerous applied and research knowledge areas. In this work, aspects related to geotechnical, geoenvironmental and geological engineering, not usually considered in applied civil or environmental engineering projects, are put forward, exemplifying the role that micro-climatic conditions may have in the development of gravitational soil mass movements such as erosion processes and natural slope stability comprising unsaturated tropical soils. Based on literature data, proposals are put forward to consider cracks that develop under dry climatic conditions in engineering projects. Additionally, laboratory testing results indicate that the shear strength of soils may decrease due to climatic drywetting cycles, potentially compromising the accuracy of slope stability analysis results. In addition, the need to evaluate initial soil-water profile conditions in flow analysis is presented and discussed under various scenarios, and the effects of further atmospheric events, such as lightning, are also presented and discussed. Furthermore, based on data collected from diverse Brazilian sanitary landfills designed to operate primarily on municipal solid waste, relationships between soil-atmospheric variables and biogas generation and emission are investigated. Finally, based on the results generated in a physical model, a type of final municipal landfill cover is presented and discussed, whose design strongly depends on atmospheric data.

Os tempos de recorrência ou períodos de retorno das precipitações intensas podem ser obtidos a partir de estimativas, sendo possível avaliar a inundação ocasionado pela elevação do nível de água dos corpos d’água de uma região. Tal avaliação possibilita mapear as manchas d’água e assim verificar as áreas que podem ser atingidas pelas inundações. Nesse contexto, este trabalho teve por objetivo avaliar séries históricas de precipitação dos postos pluviométricos situados próximo à área do Lixão do Roger em João Pessoa-PB, estimar as precipitações máximas utilizando distribuição de probabilidade contínua (Gumbel) para diferentes tempos de recorrência e mapear as inundações geradas por estas precipitações associadas aos tempos de recorrência estudados, visando a segurança na área para implantação de um parque. A partir da modelagem hidrológica e da delimitação permitiu identificar as áreas de inundação na área do Lixão do Roger e prever a cota altimétrica atingida pelas manchas de inundação para cada tempo de recorrência. Para o Posto Cabelo Cagepa e considerando um tempo de recorrência de 100 anos é possível verificar que até 30% da área do Lixão do Roger é atingida por inundações e a cota altimétrica interceptada pela água foi de aproximadamente 5,87 m.

Objective: The aim of this study is to assess the air and water permeability of soil mixtures with organic compost in different proportions in order to determine the gas and liquid fluxes for use in landfill cover layers. Method: The methodology adopted for this study includes laboratory tests to characterize the materials and the use of the flexible wall permeameter model Tri-flex 2 from Soil Test – ELE to determine the air and water permeability of the materials. Mixtures in proportions of 2:1 (soil:compost) and 1:1 (soil:compost) were used as materials for the oxidative covering layer. Results and Discussion: Based on the results obtained, it is possible to conclude that the mixtures present permeabilities to air and water in accordance with the standards indicated by USEPA (2003) for covering layers in sanitary landfills, thus ensuring that there is no excess percolation of water from rain, as well as the emission of polluting gases into the atmosphere. Research Implications: The studied material is potentially suitable for use in oxidative cover layers for sanitary landfills, proving to be a viable alternative for implementation in smaller municipalities with less purchasing power, reducing the need to use clay materials, without detriment to the operational efficiency of the landfill. Originality/Value: One of the difficulties faced by municipalities in using sanitary landfills is the search for suitable materials, especially in municipalities with lower purchasing power or located in arid regions, where the use of conventional layers presents problems, with drying out and opening of fissures. The relevance and value of this research are evidenced by the feasibility of combining clay soils with organic compost to create oxidative cover layers, reducing the pollutant load of organic waste.

Objective: The aim of this study is to investigate the analysis of the geotechnical behavior of pure soil and mixtures of soil with composted product for use in landfill cover layers. Method: The methodology adopted for this research includes laboratory tests for the physical characterization and determination of the properties of the materials used for the oxidative cover layer. To prepare the oxidative layer, it was necessary to mix organic compost with clay soil. The soil was collected from a deposit located near the Muribeca Landfill in Pernambuco. Results and Discussion: The analyses performed allowed a positive assessment of the geotechnical capacity that the mixtures can provide under the condition of landfill cover layers. The mixtures had a small increase in the proportion of coarser granulometry, reducing the plasticity of the material with the addition of the compost, possibly increasing the permeability of the layer. Also, the addition of compost did not cause a great loss in the geotechnical load-bearing capacity of the material. Research Implications: The material studied has shown potential suitability for use in oxidative covering layers for landfills, proving to be a viable alternative for implementation in smaller municipalities with less purchasing power, effectively reducing the need for the use of clayey materials, without compromising the safety of operation and subsequent use of the landfill site. Originality/Value: One of the difficulties encountered by municipalities in the use of landfills is the search for materials suitable for the solution, especially in municipalities with less purchasing power or located in arid regions, where the use of conventional layers presents problems, with drying out and opening of fissures. The relevance and value of this research are evidenced by the viability of the association of clayey soils with organic compost for the preparation of oxidative covering layers, reducing the pollutant load of organic waste.

Understanding the geotechnical behavior of a municipal solid waste landfill (MSW) requires the filtering of several studies. Regarding the mechanical behavior, there are several discussions about the conditions for the stability maintenance of these structures. This stability depends a priori on the resistance of the compacted material to remain itself stable in a way that it does not generate ruptures or slips. Of various materials compacted found in the MSW landfills, high percentages of fibers (such as plastic, fabric and wood) are verified, these materials have a great influence on the mechanical behavior of the structure. These fibers in turn produce in general an increase in the geotechnical parameters: cohesion (c), friction angle (ϕ) and tensile (ζ), which consequently increase the degree of stability of the landfill. In this context, the present work performed evaluations of the effect of fiber tensile and shear strength in samples of Muribeca’s MSW landfills, the analyzes were performed by laboratory tests using a specimen of aged residues collected in the field, with a deposition age of 10 years. With the collected sample, direct shear tests were performed on 3 different sample proportions of fibers: 0%, 16.17% and 32.33%, in two conditions of test: flooded and non-flooded. From the results obtained in the tensile angles (ζ) in the condition of flooded of 10.2° and 5.0°, for the percentages of 16.17% and 32.33%, respectively.

Dumps consist of inadequate disposal of solid waste, causing soil and water contamination, air pollution, and proliferation of vectors. After the landfill's closure, it continues to cause environmental damage and public health, requiring adequate site remediation. Thus, an ecological diagnosis is necessary to characterize the environmental situation found before carrying out the closure project. Therefore, this diagnosis should represent the first stage and the basis for all projects, where it is possible to describe and identify environmental impacts and point out the best ways to mitigate these generated impacts. This study aimed to evaluate the ecological effects of the Céu Azul dump in Camaragibe, Metropolitan Region of Recife, Pernambuco. The investigation began employing the physiographic characterization of the area, where the climate, hydrology, geology, geomorphology, and pedology of the region of the old dump. Subsequently, field and laboratory tests, such as SPT-type soundings, infiltration tests, flow plates, soil collection, and surface and underground water quality in the surrounding area, were carried out. Regarding the assessment of environmental impacts, the main impacting factors verified in areas of final waste disposal were first drawn up (whether or not an occurrence was confirmed). After this step, each impact was hierarchized in such a way as to allow a more precise visualization of the diagnostic scenario. In the case analyzed, the Camaragibe municipal dump has negative environmental impacts, which require remediation of the area.

Objective: The objective of this study is to carry out mathematical modeling in the generation of methane gas, through two mathematical models, using standard data and data obtained in the laboratory. Theoretical framework: The emission of methane gas, generated by the decomposition of solid waste in landfills, is one of the serious problems of air pollution and one way to minimize the impacts of methane on the environment is through its use to generate energy. To this end, there are ways to estimate the generation of CH4 during the useful life of the landfill. Method: For modeling, the computer programs of LandGEM and the Intergovernmental Panel on Climate Change (IPCC) were used to carry out the theoretical estimate of CH4 production during the useful life of the Agreste Alagoano landfill in two scenarios: one with standard program values for the local climate region and another with information obtained from experimental data from research by Santana (2022). Results and Discussion: When standard input data was adopted, the LandGEM model presented a 38% higher value in CH4 production compared to the IPCC model. When considering input data obtained experimentally, the IPCC showed CH4 generation 32.66% higher than the LandGEM, this was possible due to the COD value that was high as a result of the L0 of the organic fraction, exceeding the theoretical value of 0.15 to the experimental value of 0.27 in the new scenario. Implications of the research: Determining parameters for modeling methane gas generation will help in managing landfill waste and its energy recovery potential, in addition to the application of mathematical models for estimating biogas production potential as tools essential for both energy and environmental studies. Originality/value: This research presents as originality the determination of experimental parameters applied to the mathematical modeling of methane gas generation in landfills in the rural region, since studies on modeling in landfills with the climatic conditions of the rural region of Brazil are not common in the literature.

Os biossistemas têm sido uma importante ferramenta na mitigação de gases de efeito estufa emitidos a partir da camada de cobertura de aterros sanitários. Independentemente da sua configuração (biojanela, biorrecobrimento ou biofiltro), essa tecnologia baseia-se, fundamentalmente, no princípio da oxidação biológica de gases de natureza orgânica, inorgânica, odorantes, entre outros, formados na massa residual durante as diferentes fases de decomposição dos resíduos sólidos urbanos. O presente trabalho traz uma síntese dos biossistemas mais comumente reportados na literatura aplicados à oxidação passiva de metano (um importante gás de efeito estufa) em camadas de cobertura de aterros sanitários. Além disso, discute os principais parâmetros relacionados à eficiência deste bioprocesso, como temperatura, pH, umidade do meio, carga de metano aplicada no biossistema, teor de matéria orgânica e nutrientes presentes no leito biofiltrante, bem como a porosidade do meio. De um modo geral, o uso de substratos de elevado teor de matéria e baixo custo, como rejeitos de processos industriais e estações de tratamento de efluentes domésticos, turfa, composto, dentre outros, tem se mostrado uma excelente alternativa como agregado do solo, contribuindo para a redução de gases de efeito estufa no setor de gestão de resíduos sólidos.