Transitioning towards a sustainable circular city: How to evaluate and improve urban solid waste management in Brazil.

A circular city (CC) promotes circular economy (CE) principles. Efficient urban solid waste management (USWM) strategies are essential for promoting a CE at the municipal level. New tools are needed to evaluate waste management (WM) and increase the reuse and recycling of materials to accelerate the transition towards a CC. These tools could assist decision and policymakers in adopting, implementing, and monitoring circular practices. This study proposes creating an index (USWM-index) to evaluate WM in urban areas and discuss how it could be better managed in future sustainable circular cities in Brazil. The index allows city managers to integratively and sustainably assess their USWM. Decision-makers can also use the index to set goals and objectives for recycling and reusing generated waste in cities. The index comprises 19 indicators and 51 sub-indicators. These elements were divided into five groups: Operational, Environmental, Political-economic, Educational, and Social. Cities can assess their performance in each group by using the USWM-index. The index was applied to four Brazilian cities. All cities had their USWM classified as average, and they did not have initiatives to transition to sustainable circular cities regarding WM. This study presents guidelines for transitioning from a linear city to a sustainable circular city in terms of WM.

Valorizing urban forestry waste through the manufacture of toys.

Urban forestry generates a huge amount of waste worldwide, resulting from the processes of pruning and suppression. Disposal in landfills reduces the useful life of these facilities and forgoes the possibility of generating income from the waste. This study investigated the manufacture of toys as a strategy to valorize urban forestry waste. For this, physical-mechanical, chemical (extractive), color and shape characterizations were performed for three species of urban trees commonly planted in Brazil, a region of Neotropical forests. Toy prototypes were developed and manufactured from wood waste. Regarding color, all studied species showed high value of the variable b*, which refers to the blue-yellow axis. Handroanthus heptaphyllus wood had the highest values of basic density (0.706 g.cm-3) and Janka hardness (1142, 1027 and 1669 kgf.cm-2 for radial, tangential and transverse directions, respectively), and had the lowest volumetric shrinkage (11.38%). The lowest content of total extractives was measured in Handroanthus heptaphyllus, 6.33%, and the greatest content was found in Spathodea campanulata, 7.01%. The average value suggested for the toy prototypes varied between $ 3.70 and $ 13.58. The urban pruning wastes of the species studied have physical, chemical and mechanical attributes suitable for the manufacture of toys. This use has strong potential for environmental, economic and social sustainability and the toys are pedagogically accepted by adults and children.

Predictive analysis of urban waste generation for the city of Bogotá, Colombia, through the implementation of decision trees-based machine learning, support vector machines and artificial neural networks.

This study presents an analysis of three models associated with artificial intelligence as tools to forecast the generation of urban solid waste in the city of Bogotá, in order to learn about this type of waste's behavior. The analysis was carried out in such a manner that different efficient alternatives are presented. In this paper, a possible decision-making strategy was explored and implemented to plan and design technologies for the stages of collection, transport and final disposal of waste in cities, while taking into account their particular characteristics. The first model used to analyze data was the decision tree which employed machine learning as a non-parametric algorithm that models data separation limitations based on the learning decision rules on the input characteristics of the model. Support vector machines were the second method implemented as a forecasting model. The primary advantage of support vector machines is their proper adjustment to data despite its variable nature or when faced with problems with a small amount of training data. Lastly, recurrent neural network models to forecast data were implemented, which yielded positive results. Their architectural design is useful in exploring temporal correlations among the same. Distribution by collection zone in the city, socio-economic stratification, population, and quantity of solid waste generated in a determined period of time were factors considered in the analysis of this forecast. The results found that support vector machines are the most appropriate model for this type of analysis.

Uso de indicadores de sustentabilidade para avaliação da gestão de resíduos sólidos urbanos na Região Metropolitana de Belo Horizonte / Use of sustainability indicators for the assessment of urban solid waste management in Belo Horizonte's Metropolitan Region, MG, Brazil

RESUMO Uma forma de avaliar o desempenho das políticas públicas relativas à gestão de resíduos sólidos é o uso de indicadores de sustentabilidade, ferramenta que permite auxiliar os gestores no processo decisório. Este trabalho objetiva contribuir para desenvolver e validar um conjunto de indicadores modificados, com base em variáveis quantitativas que considerem as diversas dimensões da sustentabilidade. A estratégia empregada para proposição dos indicadores consistiu na revisão bibliográfica de documentos nacionais e internacionais, seguida da análise de sua aplicabilidade na gestão em municípios da Região Metropolitana de Belo Horizonte. O resultado é a proposição de um conjunto de 16 indicadores, validados em 3 municípios, cujos valores expressam tendências à sustentabilidade e mostram as deficiências da gestão.

ABSTRACT A way to assess the performance of solid waste-management public policies is by using sustainability indicators, a tool that assists managers in making decisions. This work aims to contribute to the development and validation of a set of modified indicators based on quantitative variables that consider sustainability's multiple dimensions. A strategy used for the proposal of indicators consisted in the bibliographic review of national and international documents followed by an analysis of their applicability in waste management in some municipalities of Belo Horizonte's Metropolitan Region. The result is a proposal of a 16-indicator set, validated in 3 municipalities, whose values express sustainability trends and show waste management deficiencies.

Uso de indicadores na gestão dos resíduos sólidos urbanos: parte II - uma proposta metodológica de construção e análise para municípios e regiões: aplicação do modelo / Use of indicators in urban solid waste management: a methodological proposal of construction and analysis for cities and regions: application of the model

RESUMO O presente trabalho teve por objetivo avaliar a gestão dos resíduos sólidos urbanos por meio da aplicação do modelo de gestão dos resíduos sólidos urbanos sustentável (MGRSUS) desenvolvido e aplicado em municípios que compõem a Região Metropolitana de Campina Grande (RMCG). O referido modelo é composto de 46 indicadores, 15 categorias de análise e quatro dimensões e estruturado por dados primários e secundários. Para a obtenção dos dados, foram realizadas entrevistas semiestruturadas e visitação in loco, além do levantamento bibliográfico e documental. Com base nos dados, verificou-se que os municípios de menor porte apresentam maiores problemas na gestão dos resíduos, o que pode estar relacionado ao fato de não possuírem uma equipe técnica para a execução dos serviços, o que reflete diretamente na qualidade ambiental urbana. Desse modo, o MGRSUS foi considerado satisfatório para os fins aos quais se propôs, haja vista foi possível traçar um panorama da gestão de cada município, possibilitando o direcionamento de ações específicas para cada lacuna identificada.

ABSTRACT This study aimed to evaluate the management of urban solid waste through the application of the management model of sustainable urban solid waste (MGRSUS) developed and implemented in municipalities that make up the metropolitan area of Campina Grande. The model is composed of 46 indicators, 15 categories of analysis and four dimensions and structured by primary and secondary data. In order to obtain those data, semi-structured interviews and on-site visits occurred, in addition to literature and documentary search. Based on those data, it was found out that the smaller municipalities have greater problems in waste management, which can be related to the fact they do not have a technical team to deliver the services, reflecting directly over the urban environmental quality. So, the MGRSUS was considered satisfactory for the purposes for which it is proposed, taking into account it was possible to give an overview of the management of each municipality, enabling the targeting of specific actions for each identified gap.