Solving the waste bin location problem with uncertain waste generation rate: A bi-objective robust optimization approach.

An efficient municipal solid waste (MSW) system is critical to modern cities in order to enhance sustainability and liveability of urban life. With this aim, the planning phase of the MSW system should be carefully addressed by decision makers. However, planning success is dependent on many sources of uncertainty that can affect key parameters of the system, for example, the waste generation rate in an urban area. With this in mind, this article contributes with a robust optimization model to design the network of collection points (i.e. location and storage capacity), which are the first points of contact with the MSW system. A central feature of the model is a bi-objective function that aims at simultaneously minimizing the network costs of collection points and the required collection frequency to gather the accumulated waste (as a proxy of the collection cost). The value of the model is demonstrated by comparing its solutions with those obtained from its deterministic counterpart over a set of realistic instances considering different scenarios defined by different waste generation rates. The results show that the robust model finds competitive solutions in almost all cases investigated. An additional benefit of the model is that it allows the user to explore trade-offs between the two objectives.

Effect of COVID-19 pandemic on municipal solid waste generation: a case study in Granada city (Spain).

The 2020 coronavirus pandemic has involved a series of political and social measures that have been adapted to the spread of the disease. Apart from the severe effects on health sector, the most effects of the pandemic have been felt in households and day-to-day life. Consequently, COVID-19 has had a significant impact on the generation of not only medical and health care waste but also of municipal solid waste production and composition. In this context, this work studied the implications of COVID-19 for municipal solid waste generation in Granada, Spain. Granada is a city where the economy is based mainly on the services sector, tourism and the University. Therefore, the impact of COVID-19 pandemic has greatly affected the city and it can be analyzed through the municipal solid waste generation. For the study of the incidence of COVID-19 in the generation of waste a period that goes from March 2019 to February 2021 has been chosen. The results show that, in the global calculation, a decrease in the generation of waste in the city is observed in this last year, reaching - 13.8%. Regarding the organic-rest fraction, the decrease in the COVID year represents - 11.7%. However, bulky waste has shown an increase in the COVID year which may be related to higher home furnishings renovation rates than in other years. Finally, glass is the waste flow that best indicates the effect of COVID in the service sector. In leisure areas, a significant reduction in the collection of glass is observed (- 45%). Supplementary Information: The online version contains supplementary material available at 10.1007/s10163-023-01671-2.

An assessment of higher-value recyclable wastes in Mexico City households using a novel waste collector citizen science approach.

The ability to accurately characterize and collect data on household waste generation and composition is essential for promoting recycling and developing city management plans. However, traditional data collection approaches in developing countries are hampered by jurisdictional and budgetary constraints. Here, we explore whether citizen science projects that collaborate with waste collectors can solve this problem and be a viable tool for addressing household waste generation across temporal and geographic boundaries. In this regard, this first study evaluated recyclable household waste generation by engaging waste collectors both door-to-door individuals and trucks as citizen scientists daily in an urbanized colony (5797 inhabitants and 1747 houses) in Mexico City between September and October 2022. To understand their distribution and consumption patterns on a regional basis, we stratified the colony's households into 2 distinct non-overlapping sub zones and one Wednesday market based on waste collectors' routine using a Geographical Information System. Results show that for seven weeks, household waste constitutes up to 12.19 t of recyclables, ranging from 99.5 to 480.8 kg/day, with 35 % cardboard, 23 % PET plastics, 21 % hard plastics, 17 % glass, and 4 % aluminum. The average amount of recyclable waste produced was 54 g/person/day, resulting in an annual recycling generation of 114 t. Statistical analysis revealed that recyclable waste generation varied by day and subzone. Furthermore, informal centers rather than municipal waste disposal facilities are in charge of the final disposition of the collected recyclables, suggesting that a substantial waste proportion may go unaccounted for in the local government's annual MSW report and calling for the implementation of formal recycling sectors. Overall, this study show how effective waste collector engagement in science can be and imply that the proposed citizen science approach is vital for future waste projects and the generation of transparent datasets in developing cities.

Analysis of healthcare waste management in hospitals of Belo Horizonte, Brazil.

Healthcare waste (HCW) management is a challenge for establishments that generate this type of waste, especially hospitals, as they are one of the largest generators. A determining factor in waste management is the amount of waste generation, which must be used for management planning. This study aims to compile and evaluate information on the management of HCW generated in Belo Horizonte's (located in Brazil) hospitals declared in their respective Healthcare Waste Management Plans (HCWMP) sent for approval by the municipality's Superintendency of Urban Cleaning. Therefore, a comparative analysis of the hospitals' generations in relation to their characteristics (nature, specialty, and size) was carried out, using the Kruskal-Wallis statistical test with post hoc in Nemenyi. For the study hospitals, a generation rate of 7.18 (6.17-8.23) kg·bed-1·day-1 was estimated, a generation rate close to that of developed countries. When comparing the generation according to the specialty of the hospitals, it was identified that the maternity hospitals (9.00 (7.05-10.90)) kg·bed-1·day-1 had a significantly higher generation rate than the low-complexity hospitals (4.75 (3.28-6.18)) kg·bed-1·day-1. It was also possible to demonstrate that the specialty and size of hospitals influence the structure available for waste storage. Finally, it can be observed that there are few treatment alternatives, with incineration and autoclaving being the technologies most commonly used by hospitals. It is expected that the results presented can serve as a reference for waste managers, in a context where there is little shared information on the subject.

Healthcare waste generation in hospitals per continent: a systematic review.

There are increasing worldwide concerns about the negative impacts of healthcare waste generated in hospitals, especially in low- and middle-income countries. Hazardous type of waste can contribute to adverse effects both in human populations and the environment because of its physical, chemical, and biological characteristics. A comprehensive view on increasing waste in the world has not been conducted to understand the breadth of the issue; thus, this paper sought to provide an analysis of hospitals' healthcare waste generation rate. Comparisons were made with Wilcoxon and Kruskal-Wallis tests for simple and multiple comparisons, to analyze nonparametric data, with post hoc by Nemenyi test. Median values indicated that hospital waste was the highest in North and South America (4.42, 1.64 kg/bed/day, respectively) and was almost nonexistent in Oceania (0.19 kg/bed/day), while the median rates for hazardous waste were the highest in Oceania (0.77 kg/bed/day). Africa was almost the lowest producer of waste in each category (0.19 and 0.39 kg/bed/day for hospital and hazardous waste, respectively). Over time, linear regression indicated that hazardous waste in Asia and Europe has increased, while in Oceania, the total waste also increased. Interestingly, in North America, it was observed a reduction in the generation for both total and hazardous waste. This information highlights the importance of understanding continent-specific characteristics and rates, which can be used to create a more individualized approach to addressing healthcare waste in the world.

Virtual Methodology for Household Waste Characterization During The Pandemic in An Urban District of Peru: Citizen Science for Waste Management.

The Covid-19 pandemic has caused the alteration of many aspects of the solid waste management chain, such as variations in the waste composition, generation and disposal. Various studies have examined these changes with analysis of integrated waste management strategies; qualitative studies on perceived variations and statistical evaluations based on waste collected or disposed in landfills. Despite this information there is a need for updated data on waste generation and composition, especially in developing countries. The objective of this article is to develop a data sampling and analytical approach for the collection of data on household waste generation and composition during the pandemic; and, in addition, estimate the daily generation of masks in the study area. The proposed methodology is based on the principles of citizen science and utilizes virtual tools to contact participants, and for the training and collection of information. The study participants collected the information, installed segregation bins in their homes and trained their relatives in waste segregation. The article presents the results of the application of the methodology in an urban district of Lima (Peru) in August 2020. The results suggest an apparent decrease in household waste per capita and a slight increase in plastics composition in the study area. It is estimated that each participant generates 0.124 masks per day and 0.085 pairs of gloves per day. The method developed and results presented can be used as a tool for public awareness and training on household waste characterization and segregation. Furthermore it can provide the necessary evidence to inform policy directives in response household waste issues and Covid-19 restrictions.

Generation of infectious waste during the COVID-19 pandemic: The case of a Brazilian hospital.

Coronavirus-19 disease (COVID-19) acquired pandemic status in March 2020. The new virus has caused serious implications in the healthcare services management, including several sectors, among them the generation of waste. Healthcare wastes (HCW) generation increased along pandemic representing a health problem due to potentially infected ones. From this perspective, the study sought to analyse the challenges and changes imposed by COVID-19 in the HCW management in a large public hospital from Brazil. For this purpose, data about the Contingency Plan prepared by the hospital and HCW generation from 2017 to 2020 were used, analysed by statistical methods. When dealing with the Contingency Plan, the Brazilian hospital adopted measures similar to other hospitals around the world as described by the literature, such as: adoption of new protocols, specific team assigned to manage actions and training of professionals and suspension of elective surgeries. Regarding the generation of HCW, there was a significant increase in the mass of biological waste with a high risk of infection. The waste of this group increased from March 2020, coinciding with the start of care for the patients infected by COVID-19. The contribution of this type of waste to total generation jumped from approximately 0.2% in previous years to almost 5% in 2020. In addition, a reduction in the average of total waste generated in kilogrammes per bed per day from 2017 to 2019 was indicated compared to the 2020. COVID-19 pandemic led to major challenges for hospitals that had to care for patients infected with the SARS-CoV-2 virus, including new protocols, changing the work shifts and training the teams in the new procedures. The biological waste with a high risk of infectiousness also increased 30 times.

Identification of inference fallacies in solid waste generation estimations of developing countries. A case-study in Panama.

The absence of sound sampling procedures and statistical analyses to estimate solid waste generation in many developing countries has resulted in incomplete historical records of waste quantity and composition. Data is often arbitrarily aggregated or disaggregated as a function of waste generators to obtain results at the desired spatial level of analysis. Inference fallacies arising from the generalization or individualization of results are almost never considered. In this paper, Panama, one of the fastest-growing developing countries, was used as a case-study to review the main methodological approaches to estimate solid waste generation per capita per day, and at different hierarchical levels (from households to the country). The solid waste generation intensity indicator is used by the Panamanian waste management authority to run the waste management system. It was also the main parameter employed by local and foreign companies to estimate solid waste generation in Panama between 2001 and 2008. The methodological approaches used by these companies were mathematically formalized and classified as per the expressions suggested by Subramanian et al. (2009). Seven inference fallacies (ecological, individualistic, stage, floating population, linear forecasting, average population and mixed spatial levels) were identified and allocated to the studies. Foreign companies committed three of the seven inference fallacies, while one was committed by the local entity. Endogenous knowledge played an important role in these studies to avoid spatial levels mismatch and multilevel measurements appear to produce more reliable information than studies obtained via other means.

Assessing the eco-effectiveness of a solid waste management plan using agent-based modelling.

Municipal Solid Waste Management is yet to be eco-effectively performed, especially in developing countries. In Brazil, a considerable fraction of waste has been improperly landfilled, generating environmental, social and economic problems. In 2018, the government of the state of Paraná released a revised version of its waste management plan, defining improvement strategies to be gradually implemented until 2038. However, these strategies' eco-effectiveness has not been forecasted, nor the plan was deployed to the regional level. This research aims to fill this gap, downscaling the plan to the region of Norte Pioneiro, simulating its implementation and monitoring environmental and economic benefits. The dynamics of waste generation, collection and disposal are investigated using an agent-based model, considering the four population growth scenarios addressed in the plan. Targets for strategies of waste reduction, collection, source-separation and charging of waste fees are modelled. Multiple simulation runs were performed and outputs assessed and discussed. Results show that, if the plan is thoroughly implemented since 2020, at least 650 kilotons of avoided CO2eq emissions and US$ 40 million in avoided expenditures can be achieved in the most conservative scenario by 2038. Implications from the strategies proposed in the plan are highlighted, and recommendations to improve the plan's eco-effectiveness are outlined.

Application of a methodology to design a municipal waste pre-collection network in real scenarios.

The design of efficient municipal solid waste (MSW) pre-collection networks can contribute to the global efficiency and sustainability of the reverse logistic chain of MSW in modern cities. With this aim, in this paper a comprehensive methodology that involves making decisions in several stages, from waste fraction classification to the final optimization of waste bins' location, was applied in two real cases of the city of Bahía Blanca, Argentina. This city, does not have much available data about waste generation and, therefore, an important fieldwork had to be performed for applying this methodology, involving estimating population density per block and waste generation rate per inhabitant, identifying the location of commercial and institutional buildings and also estimating its generation rate, as well as performing a characterization of the MSW from similar studies in the literature and surveys performed to make decisions. The modelling of the urban characteristics was performed in a geographic information system. In the bins' location problem, a mixed-integer optimization model was applied, seeking to minimize the investment costs, given the maximum area available and the capacity of the bins. Different scenarios were analysed, considering different collection frequencies and the maximum distance to be travelled by the user.

Estimating the generation of household e-waste in municipalities using primary data from surveys: A case study of Sao Jose dos Campos, Brazil.

Estimating the generation of Waste from Electrical and Electronic Equipment (WEEE) in municipalities is relevant for the adequate planning of take-back systems. However, current WEEE estimation studies have focused primarily at the country level, and relied mostly on secondary data from literature, especially when adopting discrete average lifespans for each type of appliance. This paper aims at developing and applying a WEEE estimation method in a Brazilian city, by obtaining primary data that reflects the differences in WEEE generation among the various social and economic profiles in the city. A survey with a stratified sample was carried out to collect representative data from each city Zone. Results show that lifespan distributions are most desirable for WEEE estimation studies than discrete averages, and that the lifespan profiles in the city are considerably different than previous values adopted in other Brazilian studies. Results also show significant variations of lifespan profiles for different types of WEEE among the different Zones of the city, which reflect the social and economic differences.

The impact of socioeconomic factors on municipal solid waste generation in São Paulo, Brazil.

Social factors have not been sufficiently explored in municipal solid waste management studies. Latin America has produced even fewer studies with this approach; technical and economic investigations have prevailed. We explored the impacts of socioeconomic factors on municipal solid waste generation in Greater Sao Paulo, which includes 39 municipalities. We investigated the relations between municipal solid waste generation and social factors by Pearson's correlation coefficient. The Student's t-test (at p ← 0.01) proved significance, and further regression analysis was performed with significant factors. We considered 10 socioeconomic factors: population, rural population, density, life expectancy, education (secondary, high and undergraduate level), income per capita, inequality and human development. A later multicollinearity analysis resulted in the determination of inequality (rp = 0.625) and income per capita (rp = 0.607) as major drivers. The results showed the relevance of considering social aspects in municipal solid waste management and isolated inequality as an important factor in planning. Inequality must be used as a complementary factor to income, rather than being used exclusively. Inequality may explain differences of waste generation between areas with similar incomes because of consumption patterns. Therefore, unequal realities demand unequal measures to avoid exacerbation, for example, pay-as-you-throw policies instead of uniform fees. Unequal realities also highlight the importance of tiering policies beyond the waste sector, such as sustainable consumption.

Generation, characterization and reuse of solid wastes from a biodiesel production plant.

The aim of this study was to identify and characterize industrial solid wastes generated by a biodiesel production plant in Brazil, as well as to present strategies for the management of these materials. This plant produces every year around 100,000tons of biodiesel from vegetable oils and animal fats. The methodology of the study included technical visits, interviews with the operational and environmental management staff as well as analysis of documents, reports and computerized data systems. An approach to reduce the generation of hazardous waste was investigated. It was take into account the amount of raw material that was processed, reduction of landfill disposal, and the maximization of the their recycling and reuse. The study also identified the sources of waste generation and accordingly prepared an evaluation matrix to determine the types of waste with the higher potential for minimization. The most important residue of the process was the filter material impregnated with oil and biodiesel, requiring, therefore, measures for its minimization. The use of these residues in the production of ceramic artefacts (light bricks) was considered to be very promising, since no significant effect on the physico-chemical and mechanical properties of the artefacts produced was observed. Phytotoxicity test using seeds of Lactuva sativa (lettuce), Brassica juncea (mustard), Abelmoschus esculentus (okra), Chrysanthemum leucanthemum (daisy), Dendranthema grandiflorum (chrysanthemum) and Allium porrum (leek) were carried out. The results clearly show incorporation of the waste material into bricks did not influence relative germination and relative root elongation in comparison to control tests.

Household hazardous wastes as a potential source of pollution: a generation study.

Certain domestic wastes exhibit characteristics that render them dangerous, such as explosiveness, flammability, spontaneous combustion, reactivity, toxicity and corrosiveness. The lack of information about their generation and composition hinders the creation of special programs for their collection and treatment, making these wastes a potential threat to human health and the environment. We attempted to quantify the levels of hazardous household waste (HHW) generated in Mexicali, Mexico. The analysis considered three socioeconomic strata and eight categories. The sampling was undertaken on a house-by-house basis, and hypothesis testing was based on differences between two proportions for each of the eight categories. In this study, HHW comprised 3.49% of the total generated waste, which exceeded that reported in previous studies in Mexico. The greatest quantity of HHW was generated by the middle stratum; in the upper stratum, most packages were discarded with their contents remaining. Cleaning products represent 45.86% of the HHW generated. Statistical differences were not observed for only two categories among the three social strata. The scarcity of studies on HHW generation limits direct comparisons. Any decrease in waste generation within the middle social stratum will have a large effect on the total amount of waste generated, and decrease their impact on environmental and human health.

Modelo para estimativa da geração de resíduos sólidos domiciliares em centros urbanos a partir de variáveis socioeconômicas conjunturais / Model to domestic solid waste generation estimative in urban areas based on socioeconomic conjuncture variables

Este trabalho apresenta um modelo matemático para estimar a geração de resíduos sólidos residenciais urbanos. O modelo foi desenvolvido a partir de uma base física espacial de bairros de Belo Horizonte e dos indicadores socioeconômicos das respectivas populações, referentes ao período de janeiro de 2006 a dezembro de 2010. Verificou-se intrínseca relação entre a geração per capita de resíduos e a renda per capita nas regiões estudadas, testificada por coeficiente de determinação de 0,85. Posteriormente, efetuou-se a validação do modelo com dados da capital de Minas Gerais e de Porto Alegre, na qual os valores estimados foram confrontados com a geração real informada pelas prestadoras de serviços de limpeza urbana locais. A despeito de elaborado com dados de Belo Horizonte e aferido com os de Porto Alegre, os resultados abrem a perspectiva de emprego do modelo proposto na estimativa de geração de resíduos sólidos em áreas urbanas.

This work presents a mathematical model to estimate the solid waste generation in urban areas. The model was developed based on spatial physic basis of neighborhoods of Belo Horizonte and of the respective economic indicators of their population. A strong relation between per capita solid waste generation and per capita income was confirmed due the high coefficient of the determination 0.85. Afterwards the model was validated by means of Belo Horizonte and Porto Alegre datasets in which the estimated values were compared with the real solid waste generation provided by the local services. Despite of data set from Belo Horizonte, the results open the perspective of the application of the model for estimating the solid waste generation in urban areas.