Sustainability Indicators in Solid Waste Management: A Case Study in a Developing Country

The generation of municipal solid waste (MSW) has been crescent. Due to this, there is a growing concern about MSW disposal. Whitin a scenario of limited financial resources, the management of MSW may be a challenge for Brazilian municipalities. Indicators can be effective instruments for assessing MSW management, as well as local socioeconomic and socio-environmental aspects. Thus, this work aimed at characterizing the MSW management in regions of the Brazilian state of Minas Gerais through an analysis of socioeconomic and sustainability indicators, considering the 10 years since the Brazilian National Solid Waste Policy. For this purpose, indicators of MSW management and socioeconomic development of municipalities of Minas Gerais were analyzed. The statistical analysis evidenced some characteristics reported in literature. Furthermore, MSW management indicators were not directly related to the available data on basic sanitation in the territories. Results also evidenced a lack of financial and economic sustainability of MSW management in the municipalities.


Introduction
Population growth and urbanization have been intensified the generation of Municipal Solid Waste (MSW) and, consequently, the demand for environmentally correct disposal solutions. Given the diversity of realities and the lack of financial resources, support tools, or capable workers, Brazilian municipalities face many difficulties in managing their MSW (Lima et al., 2017).
The concept of MSW management, created in the 1990s, includes planning and operation practices of MSW management systems from social, technical, and operational perspectives. Regarding the social dimension, the attribution of the different actors involved in management may be assessed from a socio-economic and socioenvironmental perspective. In this sense, environmental education is a fundamental tool, which allows the valuation of the work of MSW collection workers and help population to build a better understanding of their responsibility in MSW management (Sabedot & Pereira Neto, 2017).
In this context, in 2010, the Brazilian National Solid Waste Policy (PNRS) was created, establishing principles, objectives, guidelines, instruments, goals, and actions for the management of MSW. The waste plans proposed in the PNRS establishes actions and targets for waste management at national, state and municipal levels. These actions includes i) eradicating of dumps; ii) requirement of waste management plans for private companies; iii) implementation of selective collection and reverse logistics; iv) promoting non-generation, reduction, reuse, recycling, and treatment of solid waste and ensuring the environmentally correct final disposal of waste; v) development and adoption of clean technologies to minimize environmental impacts; vi) technical and financial cooperation between public management and business sector; vii) training of workers and technical staff; viii) universalization of public services for solid waste management and urban cleaning; ix) promoting life cycle assessments; and x) encouragement to sustainable consumption (Brasil, 2010) MSW management includes generation, conditioning, collection, transport, transfer, treatment, and final disposal. MSW generation varies with socioeconomic and regional conditions, as well as the proportion of organic and recyclable wastes. In 2018, the average generation per capita in Brazil was 1.039 kg/day, representing a total of 79 million tonnes (Abrelpe, 2019). The annual monitoring of waste generation can also be an indication of improvement of country's economic conditions, since the amount waste generated may be related to the population's purchasing power.
According to Santiago & Dias (2012), environmental indicators may be an important tool for evaluating and monitoring MSW management. They may attest the sustainability degree of the management model and guide plans and strategies for further improvements. Furthermore, indicators are an intelligible way to inform the population about statistical, scientific, and technical data. Fernandes et al. (2012) argue that socio-environmental planning based on sustainability indicators not only enables partnerships between government and society, but also promotes trust, dynamism, and visibility to the data studied.
Thus, this work aimed at characterizing the management of MSW in the Brazilian state of Minas Gerais, through an analysis of socioeconomic and sustainability indicators, considering a legal and regulatory framework of the 10 years of the PNRS.

Study Area
This work had the Brazilian state of Minas Gerais as its study area. As established by the Secretariat of Planning and Management (SEPLAG), municipalities of Minas Gerais are divided into Development Territories. This division has been valid since 2015 and it is based on social, economic, and territorial characteristics. Figure 1 shows the 17 Development Territories of Minas Gerais: Alto Jequitinhonha, Caparaó, Central, Mata, Médio e Baixo Jequitinhonha, Metropolitano, Mucuri, Noroeste, Norte, Oeste, Sudoeste, Sul, Triângulo Norte, Triângulo Sul, Vale do Aço, Vale do Rio Doce, and Vertentes (Seplag, 2015).

Data Collection
Data regarding the indicators shown in Table 1 were collected considering the period from 2009 to 2018. This jsd.ccsenet.org Journal of Sustainable Development Vol. 14, No. 5;2021 period was chosen in order to analyze the evolution of MSW management considering the 10 years of enactment of the PNRS.
The selection of indicators was made prioritizing national indicators or those adapted for the Brazilian reality, aiming to consider regionalities and socioeconomic and environmental aspects of MSW management. Thus, indicators already consolidated in Brazil and which were applied for the studied municipalities between 2009 and 2018 were selected.
IFDM was created in 2005 by the Federation of Industries of the State of Rio de Janeiro (Firjan). It assesses socioeconomic development in the Brazil through three main pillars: i) employment and income, ii) education, and iii) health. IFGF was created in 2012 by Firjan and it aims to assess the efficiency of fiscal management, focusing on the administration of public resources by municipalities. ISLU was created in 2016 by the National Union of Urban Cleaning Companies, and its main objective is to define how much each municipality complies with the PNRS through urban cleaning and actions of MSW management. Data about MSW disposal in municipalities were obtained from the State Environmental Foundation (Feam, 2019). Municipalities that employ an environmentally correct MSW disposal (through sanitary landfills or sorting and composting units) were initially selected. After analyzing the municipalities that have an environmentally correct MSW disposal, a second selection was made. During this step, municipalities that did not had data for the selected indicators for at least one year between 2009 and 2018 were excluded. The purpose of this filter was to define a consistent dataset for the statistical analyses. Thus, data from 84 municipalities were selected for the analyses. Consequently, some Development Territories could not be included in the analysis. Thus, the assessment of MSW management carried out in this work comprised the following Development Territories: Mata (17), Metropolitano (10), Triângulo Sul (8), Vertentes (14), Triângulo Norte (4), Sul (16), Caparaó (15), and Noroeste (1) ( Figure 1).
Additionally, data on the coverage of water supply and sewage collection services in the selected territories were obtained (Trata Brasil, 2020). Data regarding the territories' Gross Domestic Product (GDP) and the portion of the population in poverty were also collected (Seplag, 2015).

Data Analysis
The Shapiro-Wilk test at 95% confidence level carried out to check if the data fits the normal distribution. As most of data series had a non-normal distribution, the median was defined as a reference measure of central tendency for comparing MSW management in the different development territories of Minas Gerais, according to Zaros & Medeiros (2011).

Panel Data Analysis
Panel data analysis consists of a regression model, in which data vary in spatial and temporal dimensions. Panel data analysis is more suitable for analyzing the dynamics of variables changing in addition to admitting more complex behavioral models than simple linear regression models (Gujarati & Porter, 2011). Thus, panel analysis was used in the study to analyze the level of dependence between sustainability indicators and specific indicators of MSW management, as shown in Equations 1, 2 and 3. Finally, the model proposed in Equation 3 aims to verify if there is a dependence between the recyclables recovery rate (IN031) and the municipal development (IFDM) and fiscal management (IFGF) of the municipalities. This equation analyzes the initial hypothesis that the management of MSW becomes more effective with the development of a municipality, increasing the percentage of recyclable waste recovery.
For the panel analysis, data from each municipality of the selected development territories were considered, aiming to compute the spatial variability also within the territories. The assumptions of panel data regression models were analyzed at 95% confidence level. Variance inflation factors for each variable were computed and the presence of multicollinearity between variables was verified. Furthermore, the presence of omitted variables, homoscedasticity, and autocorrelation in the models were also assessed. Panel data analysis was performed using Stata Version 12 software.

Results and Discussion
The National Solid Waste Policy (PNRS) is the main regulatory framework for waste management in Brazil, in which several guidelines and goals for a sustainable MSW management were established. One of the main goals of the PNRS is promoting an adequate disposal of refuses, which includes eradicating dumps and controlled landfills. In this context, environmentally correct MSW disposal in Brazil has shown progress over the years since the creation of the PNRS (Figure 2). However, as it can be seen, it is far from the minimum percentage of 95% from which it can be considered a universal service.  Vol. 14, No. 5;2021 In 2019, the state of Minas Gerais had 21,168,791 inhabitants in a territory of 586,521,123 km² (Ibge, 2020). Minas Gerais is the state with the largest number of municipalities in Brazil, comprising an amount of 853 municipalities, which represents more than 15% of the Brazilian municipalities. Minas Gerais is also the fourth largest Brazilian state and has the second largest population of Brazil (Ibge, 2020). In 2010, the human development index (HDI) of Minas Gerais was 0.731, whereas Brazil's HDI was 0.724 (Ibge, 2020). Furthermore, the monthly household income per capita in Brazil in 2020 was about 260 USD, while in Minas Gerais, it was about 250 USD (Ibge, 2020). Due to these aspects, Minas Gerais can greatly represent the Brazilian reality.
In terms of MSW management, in 2018, 46.1% of the Brazilian municipalities had an environmentally correct MSW final disposal service (Brasil, 2020a).   Table 2. Values expressed in Table 2 and the map of Development Territories (Figure 1) show that socioeconomic variability are spatially concentrated. Territories further North and far from the large centers concentrate the largest portion of the population in poverty. For example, Alto Jequitinhonha, Médio e Baixo Jequitinhonha, and Mucuri had the largest proportions of population in poverty and they are located in the Northeast region of the state of Minas Gerais. Meanwhile, the Metropolitano territory, where Belo Horizonte (capital of Minas Gerais) is located, had the highest population density and the third lowest concentration of population in poverty in the state. Triângulo Sul had the lowest concentration of population in poverty, followed by Triângulo Norte, both located at the opposite end of the poorest development territories of the state of Minas Gerais. The favorable economic situation of these two development territories may be explained by the fact that they concentrate six industrial centers, having the largest agricultural production in the state of Minas Gerais, in addition to having a strong tourist appeal (Seplag, 2015). Socioeconomic aspects guide the geographic and spatial dimensions. In a more comprehensive analysis, it is possible to compare this same socioeconomic information with the heterogeneity of basic sanitation services.
In 2018, 83.62% of the Brazilian population had access to the drinking water supply networks, whereas 53% were served with sewage collection networks (Trata Brasil, 2020) and 92.1% with collection of MSW. Furthermore, 75.6% of the Brazilian population that had access to MSW collection services had an appropriate MSW disposal (Snis, 2019). It is plausible to say that the same territories that have the best socioeconomic conditions have access to basic sanitation services in better conditions than the national average. On the other hand, territories with the worst socioeconomic conditions have worse indicators than the national average. In the latter case, there are even worrying scenarios, such as the case of Alto Jequitinhonha and Médio e Baixo Jequitinhonha. Less than 70% of the population of these territories had access to drinking water supply services, and less than 10% of the population is served with an environmentally correct MSW disposal, a fact that may represent a risk to the population health.
IFDM and IFGF are indicators of municipal development and fiscal management, respectively. The territories that had the highest medians of IFDM and IFGF were Caparaó (0.7741 and 0.7556, respectively), Noroeste (0.7525 and 0.6407, respectively), Triângulo Norte (0.7522 and 0.6147, respectively), and Triângulo Sul (0.7528 and 0.5941, respectively), while the territory Vertentes had the second lowest median for both indicators (IFDM = 0.7244 and IFGF = 0.4163). These data reaffirm the high development rates of Triângulo Sul and Triângulo Norte territories, which had high Gross Domestic Products (GDP) (5.5% and 9.0% respectively), and low proportion of population in poverty (23.8% and 24 0.0% respectively). However, these indicators do not support the same information for Mata and Caparaó territories. Mata had a higher GDP (5.7%) and lower concentration of population in poverty (37.8%) than Vertentes (3.0% and 60.0%, jsd.ccsenet.org Journal of Sustainable Development Vol. 14, No. 5;2021 respectively) and Noroeste (3.2% and 41.0%, respectively). However, Vertentes and Noroeste IFDM and IFGF higher than Mata. Furthermore, Caparaó had the highest medians for IFDM and IFGF indicators (0.7741 and 0.7556). However, Caparaó had a GDP that corresponds to 2.0% of the total of Minas Gerais and the concentration of population in poverty represented 41.77% of its population.
ISLU is an indicator of the sustainability urban cleaning services, which considers socioeconomic data, such as the HDI, tax collection, waste recovery, and the rate of population served by MSW management services. The development territories that had the highest medians for ISLU were Metropolitano (0.6815), Triângulo Sul (0.6815) and Sul (0.6770), respectively, while Triângulo Norte had the lowest median (0.6105). The large medians of ISLU in Metropolitan and Triângulo Sul seem to be supported by the high rate of MSW collection MSW (95.9% and 92.8%, respectively) and regularized MSW disposal (85.0% and 80.0%, respectively). On the other hand, the ISLU of Triângulo Norte contrasts with the high MSW collection rate (93.2%), which was the second highest percentage among the territories, and high rate of regularized MSW disposal (70.5%), which was the fourth highest percentage of regularized waste disposal. It is important to emphasize that an increase in the cost of MSW management over the years is expected, since it generally follows increases in MSW generation, which is strictly related to the population's purchasing power (Lima et al., 2017). However, it was noticed that the collected revenue and the recyclables recovery rate did not follow the costs with MSW management in most of the development territories of Minas Gerais.
Generally, the recyclables recovery rate is very small compared with the total amount of MSW collected. This fact may be related to the difference between cost and revenue of MSW management, since municipalities do not have a sufficient structure for the collection and treatment of recyclables, resulting in a deficient supply chain (Feitosa et al., 2020).
Results of the panel data analysis are shown in show that the revenue for MSW management tends to grow with increasing costs, as expected. This relationship between the indicators is explained through the adoption of fees, tariffs and other public prices charged for urban cleaning and MSW management as essential instruments to promote environmental sustainability, as ratified by Brazilian Federal Law nº 14,026/2020 (Brasil, 2020b). Revenues guarantee financial resources for MSW collection and management services as well as for fiscal, by releasing a significant part of municipal resources previously destined to financing these services for other purposes of public interest (Ribas & Pinheiro, 2018). Equation 3 shows the model that had recyclables recovery rate (IN031) as dependent variable and the municipal development (IFDM) and fiscal management (IFGF) as independent variables. These indicators did not show a significant correlation (p-valor > 0.05). Municipal planning to deal with MSW management is a continuous process, observing the potentialities related to waste recycling (Silva et al., 2017). Thus, it is reasonable to expect that the recyclable recovery rate tends to grow with the municipal development and a sustainable fiscal management, a fact evidenced by the direct relationship between the independent and dependent variables presented by the proposed model.
Results obtained in the panel analysis highlight, especially, the economic aspects that permeate MSW management. Considering that the territories that had the best socioeconomic conditions, have the highest rates of attendance of basic sanitation services, it is reasonable to say that sanitation acts as an indicator of the development of a municipality, since the sanitation helps in understanding social and economic issues (Nguyen-Viet et al., 2009).

Conclusions
Indicators of municipal solid waste management (MSW) and environmental and socioeconomic development of municipalities of Minas Gerais were analyzed, aiming at assessing MSW management in the 10 years since the Brazilian National Solid Waste Policy (PNRS). As a first step in the statistical analysis, a descriptive analysis was performed to compare the indicators. In this analysis, it was possible to notice that some of the characteristics of territories present in the literature were supported, such as the socioeconomic indicators IFDM (FIRJAN Municipal Development Index), IFGF (FIRJAN Tax Management Index), the values of Gross Domestic Product (GDP), and the proportion of population in poverty. As expected, municipalities that had best socioeconomic conditions generally offer best basic sanitation services, including MSW collection, destination, and disposal services. Unbalanced expenditure and revenue evidenced a worrying situation in terms of financial and economic sustainability of MSW management.
Results obtained through panel data analyses show the association between costs and revenues for MSW management and the municipal fiscal management, showing an association between MSW management and economic indicators. Furthermore, it is worthwhile to mention that MSW is an action of shared responsibility. Population is responsible to properly separating and packaging their waste, whereas and the municipalities are responsible to collect, transport, treat and dispose of these wastes. Although federal agencies generally support local MSW management regulations, there are some divergences in actions, making the solid waste scenario still critical and with a worrying future.