Environmental Sustainability Impacts of Solid Waste Management Practices in the Global South

1Solid waste management (SWM) continues to dominate as a major societal and governance challenge, especially in urban areas overwhelmed by the high rate of population growth and garbage generation. The role of SWM in achieving sustainable development is emphasized in several international development agendas, charters, and visions. For example, sustainable SWM can help meet several United Nations’ Sustainable Development Goals (SDG), such as ensuring clean water and sanitation (SDG6), creating sustainable cities and inclusive communities (SDG11), mitigating climate change (SDG13), protecting life on land (SDG15), and demonstrating sustainable consumption and production patterns (SDG12) (https://sdgs.un.org/goals, accessed on 26 September 2022). It also fosters a circular urban economy that promotes reductions in the consumption of finite resources, materials reuse and recycling for waste elimination, pollution reduction, cost saving, and green growth

2However, coupled with economic growth, improved lifestyle, and consumerism, cities across the globe will continue to face an overwhelming challenge of SWM as the world population is expected to rise to 8 billion by 2025 and to 9.3 billion by 2050, out of which around 70% will be living in urban areas. In developing countries, most cities collect only 50–80% of generated waste after spending 20–50% of their budgets, of which 80–95% are spent on collecting and transporting waste. Moreover, many low-income countries collect as low as 10% of the garbage generated in suburban areas, which contributes to public health and environmental risks, including higher incidents of diarrhea and acute respiratory infections among people, particularly children, living near garbage dumps. Obstacles to effective municipal SWM include lack of awareness, technologies, finances, and good governance.

3Removing garbage from homes and businesses without greater attention to what was then carried out with it has also been the priority of municipal SWM in several cities of developing countries. In most developing countries, garbage collected from households is disposed of in landfills or dumpsites, the majority of which are projected to reach their capacities within a decade. The unsustainable approach of dumping or burning waste in an open space, usually near poor communities on the city edge, or throwing garbage into water bodies was an acceptable garbage disposal strategy. Similarly, several cities still use old-generation or poorly managed facilities and informal uncontrolled dumping or open-air waste burning. Often, these practices affect marginalized social groups near the disposal sites. Moreover, this approach poses several sustainability problems, including resource depletion, environmental pollution, and public health problems, such as the spread of communicable diseases.

4However, ever since the advent of the environmental movement in the 1960s, there has been a far-reaching appreciation of environmental and public health risks of unsustainable SWM practices. In the 1970s and onward, SWM was a technical issue to be resolved using technology; hence, the emphasis and investments were placed on garbage collection equipment. Although modern technology can significantly reduce emissions of hazardous substances, by the 1990s, that viewpoint changed when municipalities become unable to evacuate and dispose of garbage effectively without the active involvement of service users and other stakeholders. The inability of the public sector in the global South to deliver sufficient improvement of SWM, coupled with the pressure from the financial institutions and other donor agencies, led to privatization policies at the end of the decade. However, as privatization failed to provide municipal SWM services to the poor and marginalized communities, the current global thinking on addressing municipal SWM problems is changing.

5A more sustainable waste management approach prioritizes practices such as reduced production, waste classifications, reuse, recycling, and energy recovery over the common practices of landfilling, open dumps, and open incineration. This approach, which is still at an early stage but getting increased attention in the Global South, is more inclusive and environment-friendly and has less negative impact on human health and the environment than the common practices. As such, there is a need to assess SWM practices in the Global South and their impacts on environmental and human health because 90% of the expected growth in the urban population by 2050 is expected to happen here. So far, there are a few studies on the impacts of SWM practices on human health and the environment in the global regions.

6Therefore, this review article addresses this knowledge gap by assessing the negative impacts of the dominant SWM practices on human and environmental health. Section 2 presents the research methodology. Section 3 reviews the major SWM practices in the Global South and assesses the environmental and public health implications of SWM practices in the Global South cities. While Section 4 discusses the implications of the findings and proffers recommendations that could help authorities to deal with SWM challenges and mitigate public and environmental health risks associated with unsustainable SWM practices, Section 5 concludes the paper.

7The present paper utilizes a desktop research method of collecting and analyzing relevant data from the existing literature, as utilized in some previous studies. The method consists of three iterative stages shown in Figure 1: (a) scoping, (b) collecting relevant literature, and (c) data analysis. Firstly, the scoping stage involves defining and understanding the research problem under investigation and setting the study scope and boundary. The scope of the paper is to explore human and environmental impacts of SWM practices toward policy and practical recommendations for a more sustainable SWM system, with the Global South as the study boundary. This stage also helped identify relevant keywords to search for during the literature review in the second stage.

8The second stage involved identifying and collecting relevant literature from online sources. The researchers utilized Google Scholar and Scopus databases to identify peer-reviewed academic works (peer-reviewed articles, conference proceedings, and books) as well as the gray literature. The literature that satisfied the following three inclusion criteria was identified and downloaded: (1) It is related to the study’s objective; (2) it is in the English language; and (3) it was published within the last twenty years, although some old documents about established concepts and approaches were also accessed. The downloaded gray literature includes newspaper articles, statistics, technical reports, and website contents from international development organizations such as the World Health Organization (WHO), the United Nations, and the World Bank.

9In the last stage, the authors organized, analyzed, and synthesized the data collected from the literature. The downloaded works were organized according to the similarity of topics, even though some fit in more than one category. Then, each document was thoroughly examined, and themes concerned with SWM practices and their human and environmental impacts were collated, synthesized, and harmonized. Finally, the themes were summarized in Table A1, Table A2 and Table A3 (see Appendix A) and discussed. Implications and recommendations of the findings are then highlighted.

10Global municipal solid waste (MSW) generation rose from 1.3 billion tons in 2012 to 2.1 billion tons (0.74 kg/capita/day) as of 2016, which by 2050 is expected to increase by 70% to reach a total of 3.40 billion tons or 1.42 kg/capita/day. The per capita MSW generation varies among regions and countries. In the EU (European Union), it ranges from 0.3–1.4 kg/capita/day, and in some African cities, the average is 0.78 kg/capita/day. In Asia, urban areas generate about 760,000 tons of MSW per day, which is expected to increase to 1.8 million tons per day or 26% of the world’s total by 2025, despite the continent housing 53% of the world’s population. In China, the total MSW generation was around 212 million tons (0.98 kg/capita/day) in 2006, out of which 91.4%, 6.4%, and 2.2% were disposed of via landfilling, incineration, and composting. In 2010, only 660 Chinese cities produced about 190 million tons of MSW, accounting for 29% of the world’s total, while the total amount of solid waste in China could reach at least 480 million tons in 2030. In China, industrial waste (more than one billion tons) was five times the amount of MSW generated in 2002, which is expected to generate approximately twice as much MSW as the USA, while India will overtake the USA in MSW generation by 2030.

11In Malaysia, while the average rate of MSW generation was about 0.5–0.8 kg/person/day, Kuala Lumpur’s daily per capita generation rate was 1.62 kg in 2008, which is expected to reach 2.23 kg in 2024. About 64% of Malaysia’s waste consists of household and office waste, 25% industrial waste, 8% commercial waste, and 3% construction waste. In Sri Lanka, the assessed mean waste generation in 1999 was 6500 tons/day or 0.89 kg/cap/day, which is estimated to reach 1.0 kg/cap/day by 2025. With a 1.2% population growth rate, the total MSW generation in 2009 was approximately 7250 tons/day. In Ghana, the solid waste generation rate was 0.47 kg/person/day, or about 12,710 tons per annum, consisting of biodegradable waste (0.318), non-biodegradable (0.096), and inert and miscellaneous waste (0.055) kg/person/day, respectively.

12Moreover, global SWM costs are anticipated to increase to about $375.5 billion in 2025, with more than four-fold increases in lower- to middle-income countries and five-fold increases in low-income countries. Globally, garbage collection, transportation, and disposal pose a major cost component in SWM systems. Inadequate funding militates against the optimization of MSW disposal services. Table 1 compares the everyday SWM practices in low-, middle- and high-income countries according to major waste management steps. The literature indicates that waste generation rates and practices depend on the culture, socioeconomic status, population density, and level of commercial and industrial activities of a city or region.

13Weak and Inadequate SWM System

14Many problems in the cities of the global South are often associated with a weak or inadequate SWM system, which leads to severe direct and indirect environmental and public health issues at every stage of waste collection, handling, treatment, and disposal. Inadequate and weak SWM results in indiscriminate dumping of waste on the streets, open spaces, and water bodies. Such practices were observed in, for example, Pakistan, India, Nepal, Peru, Guatemala, Brazil, Kenya, Rwanda, South Africa, Nigeria, Zimbabwe, etc.

15The problems associated with such practices are GHG emissions, leachates, the spread of diseases such as malaria and dengue, odor, blocking of drains and sewers and subsequent flooding, suffocation of animals in plastic bags, and indiscriminate littering.

16Irregular Waste Collection and Handling

17Uncollected and untreated waste has socioeconomic and environmental costs extending beyond city boundaries. Environmental sustainability impacts of this practice include methane (CH4) emissions, foul odor, air pollution, land and water contamination, and the breeding of rodents, insects, and flies that transmit diseases to humans. Decomposition of biodegradable waste under anaerobic conditions contributes to about 18% and 2.9% of global methane and GHG emissions, respectively, with the global warming effect of about 25 times higher than carbon dioxide (CO2) emissions. Methane also causes fires and explosions. Emissions from SWM in developing countries are increasing due to rapid economic growth and improved living standards.

18Irregular waste collection also contributes to marine pollution. In 2010, 192 coastal countries generated 275 million metric tons of plastic waste out of which up to 12.7 million metric tons (4.4%) entered ocean ecosystems. Moreover, plastic waste collects and stagnates water, proving a mosquito breeding habitat and raising the risks of dengue, malaria, and West Nile fever. In addition, uncollected waste creates serious safety, health, and environmental consequences such as promoting urban violence and supporting breeding and feeding grounds for flies, mosquitoes, rodents, dogs, and cats, which carry diseases to nearby homesteads.

19In the global South, scavengers often throw the remaining unwanted garbage on the street. Waste collectors are rarely protected from direct contact and injury, thereby facing serious health threats. Because garbage trucks are often derelict and uncovered, exhaust fumes and dust stemming from waste collection and transportation contribute to environmental pollution and widespread health problems. In India’s megacities, for example, irregular MSW management is one of the major problems affecting air and marine quality. Thus, irregular waste collection and handling contribute to public health hazards and environmental degradation.

20Landfilling and Open Dumping

21Most municipal solid waste in the Global South goes into unsanitary landfills or open dumps. Even during the economic downturn during the COVID-19 pandemic, the amount of waste heading to landfill sites in Brazil, for example, increased due to lower recycling rates. In Johor, Malaysia, landfilling destroys natural habitats and depletes the flora and fauna. Moreover, landfilling with untreated, unsorted waste led to severe public health issues in South America. Based on a study on 30 Brazilian cities, Urban and Nakada report that 35% of medical waste was not properly treated before disposal, which poses a threat to public health, including the spread of COVID-19. Landfills and open dumps are also associated with high emissions of methane (CH4), a major GHG. Landfills and wastewater release 17% of the global methane emission. About 29 metric tons of methane are emitted annually from landfills globally, accounting for about 8% of estimated global emissions, with 1.3 metric tons released from landfills in Africa. The rate of landfill gas production steadily rises while MSW accumulates in the landfill emissions. Released methane and ammonia gases can cause health hazards such as respiratory diseases. Since methane is highly combustible, it can cause fire and explosion hazards.

22Open dumping sites with organic waste create the environment for the breeding of disease-carrying vectors, including rodents, flies, and mosquitoes. Associated vector-borne diseases include zika virus, dengue, and malaria fever. In addition, there are risks of water-borne illnesses such as leptospirosis, intestinal worms, diarrhea, and hepatitis A.

23Odors from landfill sites, and their physical appearance, affect the lives of nearby residents by threatening their health and undermining their livelihoods, lowering their property values. Moreover, the emission of ammonia (NH3) from landfill sites can damage species’ composition and plant leaves. In addition, the pollutants from landfill sites damage soil quality. Landfill sites also generate dust and are sources of noise pollution.

24Air and water pollution are intense in the hot and rainy seasons due to the emission of offensive odor, disease-carrying leachates, and runoff. Considerable amounts of methane and CO2 from landfill sites produce adverse health effects such as skin, eyes, nose, and respiratory diseases. The emission of ammonia can lead to similar problems and even blindness. Other toxic gaseous pollutants from landfill sites include Sulphur oxides. While less than 20% of methane is recovered from landfills in China, Western nations recover up to 60%.

25Several studies report leachate from landfill sites contaminating water sources used for drinking and other household applications, which pose significant risks to public health. For example, Hong et al. estimated that, in 2006, the amount of leachates escaping from landfill sites in Pudong (China) was 160–180 m3 per day. On the other hand, a properly engineered facility for waste disposal can protect public health, preserve important environmental resources, prevent clogging of drainages, and prevent the migration of leachates to contaminate ground and surface water, farmlands, animals, and air from which they enter the human body. Moreover, heat in summer can speed up the rate of bacterial action on biodegradable organic material and produce a pungent odor. In China, for example, leachates were not treated in 47% of landfills.

26Co-mingled disposal of industrial and medical waste alongside municipal waste endangers people with chemical and radioactive hazards, Hepatitis B and C, tetanus, human immune deficiency, HIV infections, and other related diseases. Moreover, indiscriminate disposal of solid waste can cause infectious diseases such as gastrointestinal, dermatological, respiratory, and genetic diseases, chest pains, diarrhea, cholera, psychological disorders, skin, eyes, and nose irritations, and allergies.

27Open Burning and Incineration

28Open burning of MSW is a main cause of smog and respiratory diseases, including nose, throat, chest infections and inflammation, breathing difficulty, anemia, low immunity, allergies, and asthma. Similar health effects were reported from Nepal, India, Mexico,, Pakistan, Indonesia, Liberia, and Chile. In Mumbai, for example, open incineration emits about 22,000 tons of pollutants annually. Mongkolchaiarunya reported air pollution and odors from burning waste in Thailand. In addition, plastic waste incineration produces hydrochloric acid and dioxins in quantities that are detrimental to human health and may cause allergies, hemoglobin deficiency, and cancer. In addition, smoke from open incineration and dumpsites is a significant contributor to air pollution even for persons staying far from dumpsites.

29Composting

30Composting is a biological method of waste disposal that entails the decomposing or breaking down of organic wastes into simpler forms by naturally occurring microorganisms, such as bacteria and fungi. However, despite its advantage of reducing organic waste by at least half and using compost in agriculture, the composting method has much higher CO2 emissions than other disposal approaches. In Korea, for example, composting has the highest environmental impact than incineration and anaerobic digestion methods. The authors found that the environmental impact of composting was found to be 2.4 times higher than that of incineration. Some reviews linked composting with several health issues, including congested nose, sore throat and dry cough, bronchial asthma, allergic rhinitis, and extrinsic allergic alveolitis.

31As discussed in the section above, there are many negative impacts of unsustainable SWM practices on the people and the environment. Although all waste treatment methods have their respective negative impacts, some have fewer debilitating impacts on people and the environment than others. The following is the summary of key implications of such unsustainable SWM practices.

32Uncollected organic waste from bins, containers and open dumps harbors rodents, insects, and reptiles that transmit diseases to humans. It also produces odor due to the decomposition of organic wastes, especially in the summer, and leachates that migrate and contaminate receiving underground and surface waters.

33Open dumps and non-engineered landfills release methane from decomposing biodegradable waste under anaerobiotic conditions. Methane is a key contributor to global warming, and it can cause fires and explosions.

34Non-biodegradable waste, such as discarded tires, plastics, bottles, and tins, pollutes the ground and collects water, thus creating breeding grounds for mosquitoes and increasing the risk of diseases such as malaria, dengue, and West Nile fever.

35Open burning of MSW emits pollutants into the atmosphere thereby increasing the incidences of nose and throat infections and inflammation, inhalation difficulties, bacterial infections, anemia, reduced immunity, allergies, and asthma.

36Uncontrolled incineration causes smog and releases fine particles, which are a major cause of respiratory disease. It also contributes to urban air pollution and GHG emissions significantly.

37Incineration and landfilling are associated with reproductive defects in women, developmental defects in children, cancer, hepatitis C, psychosocial impacts, poisoning, biomarkers, injuries, and mortality.

38Therefore, measures toward more sustainable SWM that can mitigate such impacts must be worked out and followed. The growing complexity, costs, and coordination of SWM require multi-stakeholder involvement at each process stage. Earmarking resources, providing technical assistance, good governance, and collaboration, and protecting environmental and human health are SWM critical success factors. As such, local governments, the private sector, donor agencies, non-governmental organizations (NGOs), the residents, and informal garbage collectors and scavengers have their respective roles to play collaboratively in effective and sustainable SWM. The following are key practical recommendations for mitigating the negative impacts of unsustainable SWM practices enumerated above.

39First, cities should plan and implement an integrated SWM approach that emphasizes improving the operation of municipalities to manage all stages of SWM sustainably: generation, separation, transportation, transfer/sorting, treatment, and disposal. The success of this approach requires the involvement of all stakeholders listed above while recognizing the environmental, financial, legal, institutional, and technical aspects appropriate to each local setting. Life Cycle Assessment (LCA) can likewise aid in selecting the method and preparing the waste management plan. Thus, the SWM approach should be carefully selected to spare residents from negative health and environmental impacts.

40Second, local governments should strictly enforce environmental regulations and better monitor civic responsibilities for sustainable waste storage, collection, and disposal, as well as health hazards of poor SWM, reflected in garbage littering observable throughout most cities of the Global South. In addition, violations of waste regulations should be punished to discourage unsustainable behaviors. Moreover, local governments must ensure that waste collection services have adequate geographical coverage, including poor and minority communities. Local governments should also devise better SWM policies focusing on waste reduction, reuse, and recycling to achieve a circular economy and sustainable development.

41Third, effective SWM requires promoting positive public attitudes toward sustainable waste management. Therefore, public awareness campaigns through print, electronic, and social media are required to encourage people to desist from littering and follow proper waste dropping and sorting practices. There is also the need for a particular focus on providing sorting bins and public awareness about waste sorting at the source, which can streamline and optimize subsequent SWM processes and mitigate their negative impacts. Similarly, non-governmental and community-based organizations can help promote waste reduction, separation, and sorting at the source, and material reuse/recycling. In Vietnam, for example, Tsai et al. found that coordination among stakeholders and appropriate legal and policy frameworks are crucial in achieving sustainable SWM.

42Fourth, there is the need to use environmentally friendly technologies or upgrade existing facilities. Some researchers prefer incineration over other methods, particularly for non-recyclable waste. For example, Xin et al. found that incineration, recycling, and composting resulted in a 70.82% reduction in GHG emissions from solid waste in Beijing. In Tehran city, Iran, Maghmoumi et al. revealed that the best scenario for reducing GHG emissions is incinerating 50% of the waste, landfilling 30%, and recycling 20%. For organic waste, several studies indicate a preference for composting and biogas generation. Although some researchers have advocated a complete ban on landfilling, it should be controlled with improved techniques for leak detection and leachate and biogas collection. Many researchers also suggested an integrated biological and mechanical treatment (BMT) of solid waste. In Kenya, the waste-to-biogas scheme and ban on landfill and open burning initiatives are estimated to reduce the emissions of over 1.1 million tons of GHG and PM2.5 emissions from the waste by more than 30% by 2035. An appropriately designed waste disposal facility helps protect vital environmental resources, including flora, fauna, surface and underground water, air, and soil.

43Fifth, extraction and reuse of materials, energy, and nutrients are essential to effective SWM, which provides livelihoods for many people, improves their health, and protects the environment. For example, recycling 24% of MSW in Thailand lessened negative health, social, environmental, and economic impacts from landfill sites. Waste pickers play a key role in waste circularity and should be integrated into the SWM system, even to the extent of taking part in decision-making. In addition, workers involved in waste collection should be better trained and equipped to handle hazardous waste. Moreover, green consumption, using bioplastics, can help reduce the negative impacts of solid waste on the environment.

44Lastly, for effective SWM, local authorities should comprehensively address SWM challenges, such as lack of strategic SWM plans, inefficient waste collection/segregation and recycling, insufficient budgets, shortage of qualified waste management professionals, and weak governance, and then form a financial regulatory framework in an integrated manner. Effective SWM system also depends on other factors such as the waste generation rate, population density, economic status, level of commercial activity, culture, and city/region. A sustainable SWM strives to protect public health and the environment.

45As global solid waste generation rates increase faster than urbanization, coupled with inadequate SWM systems, local governments and urban residents often resort to unsustainable SWM practices. These practices include mixing household and commercial garbage with hazardous waste during storage and handling, storing garbage in old or poorly managed facilities, deficient transportation practices, open-air incinerators, informal/uncontrolled dumping, and non-engineered landfills. The implications of such practices include air and water pollution, land degradation, climate change, and methane and hazardous leachate emissions. In addition, these impacts impose significant environmental and public health costs on residents with marginalized social groups affected mostly.

46Inadequate SWM is associated with poor public health, and it is one of the major problems affecting environmental quality and cities’ sustainable development. Effective community involvement in the SWM requires promoting positive public attitudes. Public awareness campaigns through print, electronic, and social media are required to encourage people to desist from littering and follow proper waste-dropping practices. Improper SWM also resulted in water pollution and unhealthy air in cities. Future research is needed to investigate how the peculiarity of each Global South country can influence selecting the SWM approach, elements, aspects, technology, and legal/institutional frameworks appropriate to each locality.