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The rapid growth of urban populations has led to a significant increase in municipal solid waste generation, raising concerns about waste disposal, environmental impact, and associated costs. This paper aims to plan a strategy for the reverse logistics of selective waste collection in a medium-sized city in Brazil to achieve more effective and economical waste collection. Firstly, the methodology of the Brazilian National Foundation of Health was applied to determine the fleet of vehicles needed to collect recyclable waste from Volunteer Delivery Stations. Subsequently, a Vehicle Routing Problem with Multiple Trips (VRPMT) was proposed as a case study for the city of Vitória, Brazil. This study represents the first application of VRPMT to a medium-sized city with geographically dispersed collection points, introducing multiple routes within a single day and presenting a paradigm shift. The results obtained from the mathematical model indicate a potential route savings of 48.7% using linear programming analysis compared to the existing municipal solid waste collection planning. The model can serve as a tool to support the planning of reverse logistics for recyclable solid waste, assisting city councils in reducing logistics costs by automatically planning standardized trips with only the input data required. However, the model's applicability is limited to small instances. Future research could consider employing a Simulated Annealing (SA) metaheuristic to solve larger instances, enabling the planning of future expansions of the selective waste collection system. [ABSTRACT FROM AUTHOR]

Objective: the objective is to compare the relative efficiency of the railways specialized in transporting iron ore (MFe) and pellets (PLMFe), which are part of the assets of mining companies and pellet plants considering the 2016 scenario. Methods: the methods used were the data envelopment analysis (DEA) technique, with the application of the output-oriented constant returns scale (CRS) model; the initial combinatorial multicriteria method for choosing the input variables; and Tobit regression as a validation strategy for the DEA model. Results: of the twelve railways evaluated, three railways were identified as efficient: Estrada de Ferro Carajás, Fortescue, and Mount Newman. Conclusions: the applied model was considered a good method to evaluate the efficiency of railways specialized in transporting MFe and PLMFe, as it determined the efficiency of each railway, suggesting the necessary increase in the output variable or adjustments in the input variables so that the railways reach the efficiency frontier. With that, companies can use the results of this study to guide future improvements to make their railways more efficient or maintain them on the frontier of efficiency. [ABSTRACT FROM AUTHOR]

Paper aims: Propose a method to calculate and evaluate the pollutants emissions generated by the track maintenance process considering the life cycle of the three components: ballast, sleepers and rail. Originality: After the literature review, we did not find any published research that quantifies, in an integrated way, the atmospheric pollutants emissions generated by the track maintenance process considering each component life cycle. Research method: The proposed method was based on the Life Cycle Assessment (LCA) methodology. The method was applied to Vitória-Minas Railway (EFVM) using its own data and data from its suppliers. Main findings: Results show that production and delivery is the phase that emits more because of the distance from the supplier to EFVM. Two maintenance locations were tested to evaluate the impact of maintenance distance in the emissions. Several analyses were done for each pollutant emission in each phase. Implications for theory and practice: The method can be used by any railway, helping managers to adopt more sustainable strategies. [ABSTRACT FROM AUTHOR]

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