Solid waste management in the context of the waste hierarchy and circular economy frameworks: An international critical review

Growing populations and consumption drive the challenges of solid waste management (SWM); globalization of transport, food production, and trade, including waste trading, distributes risks worldwide. Using waste hierarchy (WH; reduce, reuse, and recycle) and circular economy (CE) concepts, we updated a conceptual waste framework used by international organizations to evaluate SWM practices. We identified the key steps and the important factors, as well as stakeholders, which are essential features for effective SWM. Within this updated conceptual framework, we qualitatively evaluated global SWM strategies and practices, identifying opportunities, barriers, and best practices. We find that, although a few exceptional countries exhibit zero‐waste compliance, most fare poorly, as exhibited by the high waste generation, incineration, and disposal (open dumping, landfilling) volumes. In the Global North, SWM strategies and practices rely heavily on technologies, economic tools, regulatory frameworks, education, and social engagement to raise stakeholder awareness and enhance inclusion and participation; in the Global South, however, many governments take sole legal responsibility for SWM, seeking to eliminate waste as a public “nuisance.” Separation and recycling in the Global South are implemented mainly by “informal” economies in which subsistence needs drive recyclable material retrieval. Imported, regionally inappropriate tools, economic constraints, weak policies and governance, waste trading, noninclusive stakeholder participation, data limitations, and limited public awareness continue to pose major waste and environmental management challenges across nations. In the context of the framework, we conclude that best practices from around the world can be used to guide decision‐making, globally. Despite variations in drivers and needs across regions, nations in both the Global North and South need to improve WH and CE compliance, and enhance stakeholder partnership, awareness, and participation throughout the SWM process. Partnerships between the Global North and South could better manage traded wastes, reduce adverse impacts, and enhance global environmental sustainability and equity, supporting UN Sustainable Development Goals. Integr Environ Assess Manag 2024;20:9–35. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).


INTRODUCTION
Humans generate waste while extracting ecosystem goods and services from their land, waterways, and cities.With the population growing apace, growth-dependent capitalism drives ever-greater consumption, waste production, and its management challenges (disposal, inclusive).Poor waste disposal methods and other factors, including urbanization, industrialization, limited resources, cultural and socioeconomic disparities, poor institutional enforcement of policies and regulations, governance, and institutional issues (corruption, lack of political will, political interference), and social exclusion (lack of cooperation from citizens), exacerbate these challenges (Amugsi et al., 2022;Khan et al., 2021;Okot-Okumu, 2012;Sarptaş & Erdin, 2015;Wilson et al., 2013).According to Chen et al. (2020), "the most current and comprehensive MSW data sets are the 'What a Waste reports,' with an updated book version published in 2018 (Kaza et al., 2018)."An extract from these documents indicates that global waste generation has increased from 1.3 (2010) to 2.0 (2016) billion tons and is expected to increase to 2.2 (2025; Hoornweg & Bhada-Tata, 2012), 2.59 (2030), and 3.4-3.8 (2050) billion tons (Kaza et al., 2018).In 2016, high-income countries generated 0.683 billion tons compared with 0.655, 0.586, and 0.093 billion tons produced by lower-middle-, upper-middle-, and low-income nations, respectively (Kaza et al., 2018).In the same year, the USA and China each generated 0.28-0.29 and 0.24 (rural) to 0.32 (urban) billion tons, respectively (Awasthi et al., 2022;Kaza et al., 2018).Although poorer regions and nations generate less waste than richer ones (Table 1), there has been a remarkable increase in waste generation trends across all countries, and this is projected to continue to do so in the coming years (Hoornweg & Bhada-Tata, 2012;Hoornweg et al., 2015;Kaza et al., 2018).
Every SWM stage, including planning, collection, storage, transportation, separation, and treatment (e.g., recycling, incineration, composting), can generate risks (Kawai & Tasaki, 2016;Schübeler et al., 1996).Without proper waste handling, negative socioeconomic, environmental, and associated health challenges are observed at local, national, and international scales (Beatriz et al., 2014;Chen et al., 2020;Dris et al., 2015).Past and present waste disposal practices are linked to harmful organic (synthetic industrial chemicals, microplastics, pharmaceutical and personal care products; Benson et al., 2021) and inorganic (metals from electronic and other wastes) chemicals in the air, surface water, groundwater (Verma et al., 2016), sediments, compost (Judy et al., 2019), soils (Hanfman, 2012;Stegmann, 2017;Watson, 2013), and the food chain (Awino et al., 2020;Cabidoche & Lesueur-Jannoyer, 2012).Figure 1 provides an example of some generic pathways by which leachate from imported and locally made consumer products in an open municipal mixed waste dumping sites can move to various environmental compartments and thus pose risk to human health and the environment (after Awino et al., 2020).Some waste-associated chemicals are toxic to the environment and humans, even at trace concentrations (e.g., Hafeez et al., 2016).These chemicals can initiate ecotoxicity, neurogenicity, and carcinogenicity, resulting in growth defects, reduced fertility, obesity, thyroid effects, and brain disorders in humans (Khan & Cao, 2011;Mahmood et al., 2014;Olujimi et al., 2010).The World Health Organization (WHO) report of 2010 presented an annual estimate of 600 million foodborne illnesses and 420 000 deaths (Havelaar et al., 2015), whereas, in 2015, it ascribed the death of more than 2 million people including children to harmful food and water microbial and chemical contaminants (World Health Organization, 2015a, 2015b), some of which were from poorly managed waste streams.In comparison to the Global North, the Global South is reported to be subject to the most air, food-, and waste-borne Global Billion tons/year 0.5 a 1.3 c (2012) 2.0 a 2.2 b,c 2.6 b,c 3.4 b,c kg/day/capita 1.2 b,c 0.7 b,c High-income Billion tons/year 0.6 b,c 0.7 b,c 0.7 c 0.8 c 0.9 c kg/day/capita 2.13 b,c 1.58 b,c 2.05 b 1.71 b 1.87 b Upper middle-income Billion tons/year 0.25 b,c 0.59 b,c 0.36 c 0.84 c 1.01 c kg/day/capita 1.16 b,c 0.69 b,c 1.59 a 0.83 a 0.99 a Lower middle-income Billion tons/year 0.38 b,c 0.66 b,c 0.96 c 0.83 c 1.24 c kg/day/capita 0.78 b,c 0.53 b,c 1.26 a 0.63 a 0.79 a Low-income Billion tons/year 0.08 b,c 0.10 b,c 0.22 c 0.15 c 0.29 c kg/day/capita 0.6 b,c 0.4 b,c 0.86 a 0.43 a 0.56 a Note: Data are from diverse sources, so may not be directly comparable.Sources: a Kaza et al. ( 2018), b Kawai and Tasaki (2016), c Hoornweg and Bhada-Tata (2012).

Waste hierarchy and circular economy frameworks
Over the years, easily available and affordable waste disposal practices have included open dumping, open burning, landfilling, stockpiling, dumping into oceans and other water bodies (Nicholls et al., 2021), and, more recently, waste trading (the international trade and/or export of waste between the rich [urban] and poor [rural] regions or countries for further treatment, disposal, or recycling; Beatriz et al., 2014).Uncontrolled open disposal began as early as 10 000 BC (Sarptaş & Erdin, 2015;Wilson et al., 2013), with ocean dumping, stockpiling, and landfilling at approximately 500 BC (Kiddee et al., 2013;Lamb et al., 2014).Given the consequences, the European sanitary revolution, 150 years of slow advancement, led to the adoption of sustainable development approaches (Zaman & Lehmann, 2011) including a waste hierarchy (WH) concept that prioritizes waste reduction, reuse, recycling, and recovery over controlled and/or unregulated disposal (Ma & Hipel, 2016;Zaman, 2015).The current 3R (reduce, reuse, and recycle) concept was adapted and refined into as many as nine or more Rs (e.g., see Figure 3A), focusing on approaches to minimizing waste, energy, and resource use (Coenen et al., 2020;Reike et al., 2018).Figure 2 illustrates a WH framing, focusing on SWM strategies.The most impactful WH strategies, which reduce or avoid waste, result from changes in production (rethink) or consumption (reduce, refuse).Once the waste is generated, WH strategies are prioritized from left to right.Separated waste can remain a resource through reuse, recycling (which requires added energy and sometimes materials), or recovery, which generates organic matter or energy.In the absence of these options, waste is either disposed of in a sanitary landfill or a controlled dump (which controls much of the emissions or leachate) or is openly dumped or burned, with no containment or control.
In the 1970s, a comparable concept, the circular economy (CE), was first developed to support 3R waste reduction (Khaw-ngern et al., 2021); this concept was developed further in the 1990s, to support eco-efficiency and reduce the life cycle impacts of production.From approximately 2010, it evolved further to address value retention in resource depletion (Reike et al., 2018).Therefore, CE framing relates and feeds into the WH from waste reduction to secondary resource reuse.Four CE strategies can affect WH strategies, including resource efficiency during production, eco-innovation to refine consumer products, consumption change, and upcycling and/or remining of waste materials FIGURE 1 Examples of potential pathways by which chemicals (e.g., microplastics, pharmaceuticals, personal care products, industrial, inorganic) can move from unregulated open municipal waste dumpsites to various environmental compartments, and thus threaten the environment, human health, and safety (after Awino et al., 2020) back into the production cycle.Although the two framings (WH, CE) have similar language, CE focuses on resource use and value retention (Figure 3), and WH focuses on waste reduction and fate.Waste hierarchy and CE framings are interlinked levels of an SWM system, with WH (in Figure 2) as a dynamic rather than a static framing.For example, waste applied as a resource in the WH eventually reaches the end of its life cycle and is downcycled (see Figure 4).Conversely, waste materials can be remined (retrieval of materials after the landfilling phase, either by informal and uncontrolled "scavenging" or by more formal and controlled "mining" processes) or upcycled (moved up the WH before disposal).
Framing and advancing SWM in the Global South: Background Waste and its emissions are transported through air, water, and land, and do not respect continental boundaries (Gilderbloom et al., 2017;Torre et al., 2021).Globalized economies have enhanced the migration of contaminants and impacts across countries; trade, tourism, and SWM practices not optimized for regional conditions have exacerbated these issues.Recognizing that environmental issues across the Global North and South are linked, global stakeholders and experts sought alternative waste management approaches to address the identified waste crisis.A 35member collaborative working group on urban management was established to identify challenges and design new strategies (Wallis et al., 2010), and a conceptual framework for SWM in low-and middle-income countries was developed.The Dutch institute NGO-WASTE refined the framework by introducing some missing but essential concepts ("what," "who," and "how" questions) that were needed to guide the waste management improvements (Wilson et al., 2013).These correspond to waste system elements (what: waste generation and handling), stakeholders (who: national and local government, service users, public and private service providers and enablers, formal and informal waste users, and nongovernmental organizations [NGOs]), and influential factors (how: political, institutional, social, economic, technical, financial, and environmental;Wilson et al., 2013).
Researchers have used this framework to generate guidelines, measure system performance, assess factors responsible for SWM system successes and failures, and provide solutions to waste issues in the Global South (Kabera et al., 2019).Guerrero et al. (2013) identified the key stakeholders and their roles played in the waste management process, and influential factors that would improve on or cause the systems' failure.Marshall and Farahbakhsh (2013) raised concerns over the health and environmental implications associated with the current system approaches (technological transfers) for integrated sustainable waste management (ISWM) in the Global South.Both researchers stated that several factors driving the development of successful policies and practices for ISWM in the Global North created challenges when applied directly (without regionspecific modifications) in the Global South.Therefore, they recommended the development of new approaches that fit local waste management contexts (needs and conditions) in the Global South.Wilson (2007) analyzed systems across countries and concluded that holistic approaches and integrated methodologies could address influential factors and their linkages in the entire waste system.He recommended locally appropriate waste systems with countryspecific conditions to address complex local challenges in many Global South countries.Wilson et al. (2013) used an ISWM framework focusing on physical components of waste systems, governance aspects, and proactive policies to assess when, where, and how such an approach could improve waste management in the Global South.He further emphasized the need for systems that involve stakeholders in decision-making, are affordable, and are suitable for local needs and conditions.
Several key insights and lessons can be drawn from this literature.(1) Despite interrelated waste challenges, the management concepts in the Global North and South have, for a long time, been treated segmentally and based predominantly on funding, policy implementation, and monitoring practices; (2) at different times, SWM systems in different countries have evolved slowly following similar stages including initiation, development, refinement, integration, and linkages; (3) waste management systems exhibit several flaws, including increased generation volumes, incineration, landfill and open dump rates, unregulated waste trading, and increased exposure risks (Kabera et al., 2019;Omwoma et al., 2017); (4) no country fully complies with sustainable WH concepts and CE frameworks; for example, countries of the Global North have failed at waste reduction and market creation for recycling as well as on the large use of incineration practice, whereas countries of the Global South have continued to dispose of waste in open spaces and exclude relevant actors (informal sector), attributing it to limited resources and infrastructure (Ezeah et al., 2013;Oteng-Ababio et al., 2013;Rodic et al., 2010); (5) despite the absence of proper chemical risk assessment frameworks in many Global South countries, there is waste trading between the North and South, whereas the South also adopts strategies and technologies from the Global North, which often do not match their local needs and conditions (Marshall & Farahbakhsh, 2013;Wilson, 2007); (6) across the world, a lack of stakeholder awareness of waste hazards (risks) and benefits (opportunities) limits inclusion and participation of relevant participants (Wilson et al., 2013).Although some progress had been achieved, significant challenges remained.Therefore, this article seeks to build on the previous framings and findings, aiming to identify barriers to and opportunities for success and broadly applicable best practices, as well as reviewing current global practices in light of the updated conceptual framework.

RESEARCH APPROACH
Several peer-reviewed articles about SWM in countries of the Global North and Global South have been published.However, most publications focus more on factors that cause urban waste management challenges in the Global South, whereas few assess similar challenges in Global North countries or provide a systematic comparison between the two economic development groups.Despite FIGURE 4 A modified conceptual waste framework for the solid waste management (SWM) process, with waste hierarchy (WH) and circular economy (CE) concepts, and the inclusion of key steps, stakeholders, and influential factors required for success (adapted from Marshall & Farahbakhsh, 2013;Schübeler et al., 1996;Wilson et al., 2013) recent improvements, efficient, effective, sustainable, and affordable systems fitting local needs and conditions and improved stakeholder awareness and involvement are needed to improve solid waste and resource management.To identify, understand, and address this waste crisis across the Global North and South countries, this review focuses on approaches that use common waste management practices and strategies; embrace broader stakeholder inclusion, coordination, and partnership in decision-making; and promote awareness of the risks and benefits of waste management practices (Guerrero et al., 2013;Wilson et al., 2013).
Waste management is a slowly evolving field, emerging at varying phases across countries globally.In the Global North, SWM evolved from open (land, ocean) dumping to European sanitary revolution, to 3Rs, and now, the CE (beyond 3Rs), whereas in the Global South, decades have passed for the same advancement to take place.Although the current effort in the Global North is to phase out landfills, an acquisition of a modern landfill in the Global South is considered an achieved, sustainable SWM step in the waste process (Wilson et al., 2013).With limited developments in waste management research and practice as well as fewer publications, across some countries and regions, old but relevant studies are still applicable, and will form part of this review.Therefore, secondary data (peer-reviewed articles, gray literature, and special reports) from 1993 to 2019 were systematically reviewed (although more recent literature on key issues was analyzed during synthesis).Journal articles were identified using six keywords (Global North and South, SWM, strategies and practices, open dumping, WH, CE, waste trading, adopted technologies, waste barriers, waste opportunities) in Scopus, Science Direct, Web of Science, Sci-finder, Google Scholar, SAGE journals, ResearchGate, Springer link databases, and the Google search engine.Gray literature and special reports from the WHO, United Nations Environment Programme, UN-Habitat, and World Bank were also reviewed.One hundred and fifty-one peerreviewed articles and 25 gray literature documents from 82 Global South and 50 Global North countries across the six continents were retrieved and systematically reviewed for quantitative and qualitative data; additionally 56 references (2020-2023) on the recent status of key issues were analyzed and synthesized.
To guide the review process, we built on the previous framings, findings, and recommendations while putting ISWM within more recent WH and CE concepts (avoiding, refusing, sharing, leasing, reusing, repairing, refurbishing, remanufacturing, redesigning, and recycling).We argue that the major influential factors of the SWM systems (physical waste system components, sustainability aspects, and stakeholder inclusion and participation) are linked and that their joint implementation will inform better decisions and improve sustainable strategies and practices.
Waste reduction requires CE thinking at every step of the chain (i.e., from cradle to grave), but feasibility, resources, and approaches differ internationally.Effective WH implementation requires regionally appropriate infrastructure for waste collection, storage, transfer, and separation, as well as regional and municipal capacity to successfully separate and process waste and to deliver a range of complicated services and mandatory products (Ahmed & Ali, 2004;Wilson et al., 2013).The feasibility, cost, efficacy, and human and environmental risks and benefits of the SWM system depend on all these factors.Therefore, we modified the SWM frameworks (Schübeler et al., 1996;Wilson et al., 2013) by integrating the current WH and CE concepts and adding missing but relevant aspects, such as the informal sector (economy), which is critical to waste management in the Global South. Figure 4 illustrates this updated conceptual waste framework (adapted from Marshall & Farahbakhsh, 2013;Schübeler et al., 1996;Wilson et al., 2013) and clarifies that successful SWM implementation requires extensive stakeholder involvement and integrated planning and infrastructure.
Circular economy strategies and WH framings are used to evaluate various systems' effectiveness and sustainability across countries (see Figure 4).Our objective is to frame and review SWM strategies and practices in the Global North and South with the aim to identify drivers for system successes (opportunities) and failures (barriers), as well as best practices and effective management interventions existing in other nations, and may be more generally applicable globally.In this paper, the updated framing emphasizes the importance of joint actions in support of system equitability, affordability, feasibility, efficiency, effectiveness, and sustainability, thereby seeking to contribute to improved waste management in the Global North and South.

Influential factors for sustainable SWM systems
Stakeholders play different roles in the implementation of influential factors.The success or failure of any SWM system depends on stakeholder awareness, inclusion, and participation (commitment) and how this influences the incorporation of influential (enabling) factors.In the context of the framing illustrated in Figure 4, this review outlines how the presence or absence of influential factors can affect the operations of SWM systems internationally.A sustainable SWM system requires appropriate technical solutions, adequate and strong organizational capacity, and stakeholder cooperation and partnerships, with integrated treatment methods to manage waste across the WH (Rodić & Wilson, 2017;Shekdar, 2009).Such a system must incorporate good governance, sound institutions, proactive policies, economic affordability, environmental efficiency, social acceptability, and public participation, where citizens can communicate and take part in planning, monitoring, and other decision-making processes (Gue et al., 2022;Shekdar, 2009).Systems must be market oriented, with flexibility for continued improvement, and tailored to community needs on a case-by-case basis (Batista et al., 2021;Giourka et al., 2020;Shekdar, 2009).Sustainable systems must also initiate collective actions, promote transparent decisions, and provide free access to information (Tremblay & Gutberlet, 2010).The system must further empower the capacities of public and private stakeholders, incorporate appropriate local community perspectives and needs, and encourage networking at local, regional, and national levels.Influencing factors (e.g., technical, sociocultural, political, environmental, financial, economic, legal, and institutional) must also be interlinked and implemented in unison (Figure 4; Zaman & Lehmann, 2011).
Governance, policy, and regulation.Ideally, governments strongly enforce SWM service provisions and/or regulations in communities, regardless of the public ability to accept or afford waste fees (Ahmed & Ali, 2004;Rodić & Wilson, 2017).Clean cities or communities exhibit good SWM frameworks and governance (Wilson et al., 2013).Good governance should be participatory, consensusoriented, accountable, transparent, responsive, effective, efficient, equitable, and inclusive while supporting and respecting the rule of law and human rights (Gbemudu & Ajabor, 2019).Such governments also serve stakeholders irrespective of race, gender, economic status, religion, or political ideologies, and encourage dialogues on public issues (Leal Filho et al., 2019;Sachs, 2012).In such systems, transparent public information flow exists, and free participation and collaboration are encouraged, especially during decisionmaking (Pereira et al., 2017;Puppim de Oliveira et al., 2013).
To some extent, several nations and municipalities have implemented such systems in support of SWM.For example, some Global North countries have legal and regulatory strategies that promote sustainable SWM practices (Batista et al., 2021;Schübeler et al., 1996;Shekdar, 2009).Several European countries have increased their information accessibility, awareness, active community engagement and participation, and industrial initiatives by investing in waste education, research, physical infrastructure, and litter prevention campaigns (Kaza et al., 2018;Mamady, 2016;Wilson et al., 2013).Sweden, Japan, Switzerland, Canada, the UK, the Netherlands, and Germany promote extended producer responsibilities (Kaza et al., 2018;Kiddee et al., 2013;Stegmann, 2017); Australia, the UK (Watson, 2013), Ireland, Norway, and Italy promote landfill levies and material bans to reduce landfill volumes (Guerrero et al., 2013;Ma & Hipel, 2016;Moloney & Doolan, 2016).Furthermore, Australia (e.g., Adelaide, Canberra), Denmark, the UK, New Zealand, and the USA (e.g., Del Norte county and San Francisco, both in California) apply container deposit schemes as zero-waste policies (Kaza et al., 2018;Zaman, 2015).This is coupled with the pay-as-you-throw (polluter pays) policy, commonly used in Italy (Messina & Tomasi, 2020), Singapore (Bai & Sutanto, 2002;Zhang, Keat, et al., 2010), Sweden, Austria, Germany, and the Netherlands (Moloney & Doolan, 2016;Watson, 2013).In the USA, San Francisco also applies robust public policy, implemented by determined political leadership, strong public-private partnerships, resident education, and financial incentives for waste reduction (Lee et al., 2014).These countries have implemented mandatory recycling and composting equally for both residents and businesses (Song et al., 2015) and banned the sale of plastic water bottles (Kaza et al., 2018).
In the Global South, many countries are creating SWMsupporting policies and frameworks.For example, China and Colombia (Kiddee et al., 2013), India and South Africa (Kaza et al., 2018;Widmer et al., 2005), Brazil (Beatriz et al., 2014;Wilson et al., 2013), and Turkey (Aydin, 2017;Sarptaş & Erdin, 2015) have extended producer responsibility, guaranteed fixed budgets, and regulated waste management guidelines.In Uganda and Botswana (Gaborone), the decentralization or privatization policy mandates urban councils to make by-laws and engage private sectors through contracts (Bolaane & Isaac, 2015;Okot-Okumu & Nyenje, 2011).In Rwanda, the public-private partnerships align with strong proactive policies, governance, and zero tolerance for corruption (Kabera et al., 2019).Rwanda also enforces a national plastic bag ban using border patrol guards to prevent illegal imports, with penalties, including fines, jail time, and public shaming (Kabera et al., 2019).In Côte d'Ivoire (Abidjan), the army polices waste disposal and disciplines stakeholders who litter the environment (Obeng-Odoom, 2018).Morocco adopted a strategy for sustainable development, making environmental sustainability a national priority (Kaza et al., 2018).Mozambique developed a 12-year national strategy that provides guidance ranging from landfill construction to the organization of waste pickers.This guidance outlines the roles of all stakeholders, including central governments, municipalities, businesses, waste pickers, residents, and NGOs (Kaza et al., 2018).In Kenya, a National Solid Waste Management Strategy was formed in 2014 as a response to citizen complaints about poor SWM; it outlines collective action and mechanisms to manage waste systematically (Amugsi et al., 2022;Kabera et al., 2019).
Many countries, however, face SWM policy and governance challenges (Fernando, 2019;Serge Kubanza & Simatele, 2020;Wilson et al., 2013).Inadequate institutional and technical capacity, limited infrastructure and structures for waste reduction, weak enforcement, and underdeveloped regulatory frameworks pose challenges to the regulation, monitoring, and/or delivery of waste services (Kaza et al., 2018;Okot-Okumu & Nyenje, 2011;Tsai et al., 2020).Public policy research institutions and wastespecific academic programs, free information flow, judiciary autonomy, and system audits are limited or nonexistent in some Global South countries.Striking the right balance between policy, governance, and institutional mechanisms is another challenge.For example, power struggles within multiparty political systems of central and local governance in some countries (e.g., Slovakia, Greece, and Haiti) have affected SWM structure, function, and decision-making processes (Bosdogianni, 2007;Bras et al., 2009;Šedová, 2016).The lack of democratic structures and competent representation of local authorities push leaders to make decisions based on their parties' interests for fear of being voted out of office (Aydin, 2017;Oteng-Ababio et al., 2013;Sarptaş & Erdin, 2015).
Sustainable SWM systems require citizen-focused leadership and well-laid-out legal and regulatory structures to avoid predicaments resulting from changes in governance or disagreements between political parties, or between central and local governments, possibly leading to abandoned waste projects.In countries experiencing social and political insurgency and civil unrest, policymakers and planners may consider SWM a low priority and limit budgets and other resources (Shekdar, 2009;Zaman & Lehmann, 2011).Rampant or unchecked corruption retards economic growth, distorts political systems, weakens administration, and undermines public interest and welfare (Amugsi et al., 2022;Okot-Okumu & Nyenje, 2011;Romano et al., 2021).A stable and effective governance is required for sustainable SMW decision-making, implementation, delivery, and enforcement.Proactive policies and good governance are needed to enforce national laws.For example, countries should implement standard six color-coded collection containers and/or bins for waste separation to reduce mixed waste generation and landfill volumes as well as risks.Effective governance and monitoring capacity are required to hold waste generators and handlers accountable.
Finance and economics (local, national, and global).Effective and sustainable SWM systems offer acceptable and affordable services to all stakeholders (Abagale et al., 2012;Rodić & Wilson, 2017).But a system's sustainability also depends on stakeholder willingness to respond to issues and funding ability (Ezeah et al., 2013;Omwoma et al., 2017).This ability of stakeholders to pay is determined by their economic status, which also influences waste collection service fees, frequency, nature of collection, and disposal sites (Ma & Hipel, 2016).In the Global North, waste service users are generally more willing and able to pay collection fees than their counterparts in the Global South (Almazán-Casali et al., 2019;Okot-Okumu & Nyenje, 2011).For compliance, some governments have devised approaches, such as tagging charges to rent fees, property taxes, product fees, utility bills (Matheson, 2022;Schübeler et al., 1996;Welivita et al., 2015), or waste quantity as well as providing government allocations or incentives for the separation of recyclables.In China (Kunming), collection fees are recovered from central government allocations; in Zambia (Lusaka) from the franchise fees, and in Brazil (Belo Horizonte) from municipal property taxes (Wilson et al., 2013).Governments in China and India also charge low waste collection fees with no penalty for nonpayers (Wilson et al., 2013).In Brazil (Belo), the government pays 100% of the waste collection fees and incorporates that cost into utility bills.In Tanzania (Moshi) and Nepal, poor urban households are not charged (Wilson et al., 2013).In Rwanda (Kigali), fees to households depend on income, with the poorest communities getting free service (Kabera et al., 2019).
In some Kenyan, Tanzanian, and Ugandan communities, the elite users are willing to pay for waste management services (Okot-Okumu & Nyenje, 2011).
The inability of some central governments to provide sufficient financial support (Guerrero et al., 2013) results in inadequate and irregular income sources, limiting SWM sustainability (Wilson et al., 2013).Many countries in the Global South depend on donor grants and loans to establish SWM projects and obtain technologies (Rodic et al., 2010;Wilson et al., 2013).Such costly technologies and the inability or reluctance of users to pay for services create unsustainable systems, undermining project success and triggering recurring waste challenges (Okot-Okumu, 2012;Saha, 2013;Siyat, 2012).This explains the different waste service coverage in countries of the Global North (100%) and Global South (40%-80%; Moloney & Doolan, 2016).
Effective consultation with service users, providers, and other enablers from the inception phase results in appropriate requirements and cost-benefit analysis for system components (Okot-Okumu & Nyenje, 2011).Using consultation, Brazil, Nepal, Malaysia, Zambia, China, and Tanzania have effectively engaged local stakeholders in managing their waste streams (Beatriz et al., 2014;Hoornweg & Bhada-Tata, 2012;Zhang, Tan, et al., 2010), sometimes without donor funding.Nepal has wellfunctioning waste systems, and charges no fees on household service despite not receiving external funding (Wilson et al., 2013).
To solve local or national waste problems in the Global North, many countries have designed country-or regionspecific SWM economic decision support models and assessment tools (Bachmann et al., 2022;Pires et al., 2011).These bespoke systems apply analytical tools, including life cycle impact assessment, material flow analysis and/or accounting, cost-benefit analysis, life cycle costing, environmental impact assessment, strategic environmental assessment, environmental management system, and environmental auditing (Kiddee et al., 2013).These tools, applied in a region-specific manner, have complicated attempts to integrate, synthesize, or analyze waste approaches (Omwoma et al., 2017;Triguero et al., 2016).Further, these systems focus principally on environmental and economic impacts but lack indicators of social drivers in SWM frameworks (Marshall & Farahbakhsh, 2013;Rodic et al., 2010).They seek to address a long-term "green agenda" (reducing human impacts on ecosystems and their natural resources, i.e., ecological sustainability), rather than the "brown agenda" (immediate environmental impacts of rapid urbanization, especially in the low-income urban settlements; Shrestha, 2019).
The application of economic instruments designed for the Global North by the Global South (Okot-Okumu, 2012; Wilson et al., 2013) has proven incompatible with the local needs and conditions, hindering local innovation in recipient countries (Guerrero et al., 2013;Oteng-Ababio et al., 2013).This, coupled with pressure to serve donor interests and objectives, may affect the SWM decision-making process, causing increased impacts in the Global South (Marshall & Farahbakhsh, 2013;Omwoma et al., 2017).
Technical and institutional requirements.Adequate technical structures and well-trained human resources are the backbone of technological development, regulation, policy implementation, and system component monitoring and supervision (Niu, 2017;Reymond et al., 2016;Zakaria et al., 2021).Limited finances can inhibit a nation's ability to purchase analytical facilities and generate research data for decision-making, creating SWM challenges (Ma & Hipel, 2016;Oguntoyinbo, 2012;Šedová, 2016).To build expertise aimed at addressing local waste problems and citizens' needs, many countries have incorporated training and research into their curricula (Guerrero et al., 2013;Wilson et al., 2013).In some countries, however, the curriculum at lower education levels is limited to basic knowledge of sanitation and hygiene rather than SWM principles, practices, benefits, and hazards (Guerrero et al., 2013;Ndejjo et al., 2019).Environmental education campaigns can also be limited, noninclusive, or fail to support awareness of waste hazards and benefits (Hafeez et al., 2016;Kouame et al., 2014;Kumwenda et al., 2014).At institutions of higher learning, potential future waste professionals are offered more theoretical than practical skills and knowledge (Ndejjo et al., 2019).This limits the graduates' technical capacities and expertise for employability and performance in SWM processes and systems (Ejaz et al., 2010;Kabera et al., 2019).This also impairs the capacity to develop national strategies to mainstream environmental policies for sustainable SWM (Oguntoyinbo, 2012;Okot-Okumu, 2012).
Infrastructure requirements.Adequate roads, good waste handling vehicles, and appropriate technologies are prerequisites for a sustainable SWM process (Fatimah et al., 2020).Many Global North countries have advanced facilities to support automated waste separation, collection at curbside points, and at treatment and disposal grounds (Munir et al., 2021).Well-equipped landfill technology, wellconstructed roads, material and energy recovery facilities, and mechanical and biological treatment systems reduce impacts and risks (Kumar & Ankaram, 2019).A lack of proactive policies, weak governance frameworks, and inadequate budget allocations can limit sustainable urban planning, including the purchase of waste handling facilities (Beatriz et al., 2014;Guerrero et al., 2013;Serge Kubanza & Simatele, 2020).Small remittances from central governments and unreliable donor loans may also force municipalities to fund operations and maintenance using the limited taxes from municipal land or equipment sales (Okot-Okumu & Nyenje, 2011;Oteng-Ababio et al., 2013).Deficiencies in infrastructure and equipment may affect waste separation, collection, transport, treatment, and disposal (Fernando, 2019;Vaccari et al., 2013).More reliable funding, locally focused innovation, and improved stakeholder awareness and involvement would reduce such obstacles.
Sociocultural factors.Public and personal perceptions, attitudes, and behaviors are the basis for informed SWM decisions (Hope & Jones, 2014;Massoud et al., 2021;Sarptaş & Erdin, 2015).These determine SWM success or failure, influencing choices on waste separation, recycling, willingness to pay, facility locations, local management structures, and disposal practices (Debrah et al., 2021;Oguntoyinbo, 2012).Despite many countries fairly incorporating social awareness campaigns into SWM systems, their technological complexity limits the inclusion and participation of waste users in decision-making (Rodic et al., 2010).In Australia, insufficient community awareness and incomplete or lacking waste data were reported to affect the consistency of artificial intelligence (AI) applications in waste management (Andeobu et al., 2022;Bernardo et al., 2023).
To implement WH-and CE-compliant SWM strategies, stakeholder behavioral change and awareness campaigns are required (Marshall & Farahbakhsh, 2013;Massoud et al., 2021).Awareness campaigns facilitate and are influenced by stakeholder behavior and acceptance of public and environmental policy (Bai & Sutanto, 2002;Fauziah et al., 2009;Mbongui-Kialo, 2022;Morone & Imbert, 2020).Continuous public education also creates strong environmental awareness in stakeholders (Debrah et al., 2021;Ezeah et al., 2013).Consequently, regulations and strong social pressure from interested friends, families, and community initiatives for donations influence household waste separation compliance (Almazán-Casali et al., 2019;Czajkowski et al., 2017;Sidique et al., 2010).Similarly, the influence of institutional, organizational, and public norms is observed in Japan (Yokohama), where waste and cleaning are valued, resulting in large numbers of volunteers and less removal expenditure, whereas in Singapore, open waste disposal (littering) is rampant, as the public shuns cleaning (Ong & Sovacool, 2012).In Taiwan, popular musical garbage trucks improved community involvement in waste separation and increased the recycling rate to 55% (Kaza et al., 2018), highlighting music as an alternative engagement strategy.However, in China (Hangzhou, Zhejiang Province), a waste management survey found that "economic inducement was more effective than social mobilization in promoting waste separation" (Xu et al., 2018).Thus, improved social understanding of SWM requirements and regulations, as well as economic incentives, would encourage stakeholder participation in the design, planning, and implementation decision-making (Sidique et al., 2010;Xu et al., 2018).
In some developing countries, waste is regarded as a public nuisance and a shameful social problem (Hemidat et al., 2022;Mamady, 2016;Okot-Okumu, 2012;Salvia et al., 2021).Consequently, its management is left to local or central governments, with assistance from public health agencies (Marshall & Farahbakhsh, 2013), and the urban poor (Triguero et al., 2016).Due to survival needs, informal waste pickers, disposal site reminers, and recyclers (mostly women, youth, and children) have created a system to manage waste for economic subsistence, thus exposing them to health risks (Ezeah et al., 2013;Obeng-Odoom, 2018;Oguntoyinbo, 2012).Societal perception, religious and cultural values, public attitude, and lack of knowledge of hazards and benefits have also stigmatized waste workers in the eyes of the public (Kaza et al., 2018;Ma & Hipel, 2016;Obeng-Odoom, 2018) and have limited service-user (citizen) participation in the SWM processes, leading to unregulated open disposal (Ong & Sovacool, 2012) and associated environmental and health risks.A lack of formal and informal stakeholder integration, incorrect institutional information, poor structures (Aparcana, 2017;Okot-Okumu & Nyenje, 2011;Tong et al., 2021), and limited recycling programs also hinder the development of sustainable SWM systems in many Global South regions (Egun, 2017).
Environmental issues.A well-designed SWM strategy may provide environmental and public health benefits, including reduced resource depletion and environmental risks (Andeobu et al., 2022;Zaman & Lehmann, 2011).Thus, most resource-constrained societies will not waste material but will find value in end-of-life products via repair, reuse, or composting (Zaman, 2015).However, as the population grows, waste can accumulate in streets and other environmental compartments, making pollution and acute public health risks a driving force for waste collection (Ejaz et al., 2010;Wilson et al., 2013).This was the basis for waste policy development in industrialized countries around the 1970s (Borowy, 2019;Sidique et al., 2010), with pollution control measures applied from waste collection to disposal to reduce impacts (Bai & Sutanto, 2002;Rajmohan et al., 2019).Since then, the Global North has designed costly technologies and policies aimed at minimizing waste disposal quantities (Andeobu et al., 2022).Increasingly, due to concerns over natural resources depletion (Marshall & Farahbakhsh, 2013), material and resource management has taken precedence, driving a growing emphasis on CE concepts, recycling, waste-to-energy, and zero-waste strategies (Negrete-Cardoso et al., 2022;Rezvani Ghomi et al., 2021).
There is a need to balance the competing drivers of economic and environmental development systems, where limited resources exist (Wilson, 2007).When governments give low priority to environmental protection, the results include inadequate handling of pollution control systems and limited stakeholder awareness and participation in the waste-reducing components (i.e., reduce, reuse, recycle, recover) of the WH (Ma & Hipel, 2016;Sidique et al., 2010) and vast quantities of uncontrolled waste (Manaf, 2009;Schübeler et al., 1996;Vinti & Vaccari, 2022).Then, a material's economic value may drive informal waste separation and recycling programs (Gall et al., 2020;Wilson et al., 2013).Although there is a push to phase out unregulated disposal areas, such efforts will need support and evidence from technological innovation, environmental monitoring, and risk assessment (Omwoma et al., 2017;Šedová, 2016;Zaman, 2014).
Technology transfer.In the Global North, sustainable SWM processes (Iyamu et al., 2020;Shekdar, 2009) are partially supported through continual design of waste technologies to suit local needs and conditions (Marshall & Farahbakhsh, 2013;Wilson et al., 2013).Sustainable manufacturing allows the production of goods with fewer environmental and health risks (Javaid et al., 2022;Zaman, 2015).In cleaner production, industries apply WH and CE principles, aiming to use less raw material and generate less waste in production (Ion & Gheorghe, 2014;Zhang et al., 2021).In the Global South, however, there exists an innovation gap caused by weaker political and cultural drivers of green innovation and limited data for decisionmaking and development of standards (Cai & Li, 2018;Shekdar, 2009;Widmer et al., 2005).Subsequently, this provides an opportunity for the Global North to market its new, advanced, and expensive technologies, spare parts, and regulatory models and tools (Omwoma et al., 2017), which may not be optimal for the Global South, given differing local needs, conditions, and waste compositions.For example, importing an inorganic waste truck to handle primarily organic wastes will create management complexities and failures (Okot-Okumu & Nyenje, 2011;Schübeler et al., 1996).
Further, donors generally fund the acquisition and building of waste infrastructure in recipient countries but rarely its operation and maintenance.This, coupled with limited local technical expertise to handle, operate, and maintain such systems, and the need to import or hire costly spare parts and expatriates from donor countries, imposes economic burdens, rendering these technologies cost-ineffective, redundant, and unsustainable (Bras et al., 2009;Okot-Okumu, 2012;Rodic et al., 2010).Weak institutions and limited financial capacity to operate and maintain SWM projects and systems after donor departure also lead to failure (Blenkharn, 2006;Da Silva et al., 2005;Guerrero et al., 2013).
Failure to devise appropriate SWM strategies to work across periods and the two development economies has also made it difficult to predict the amount and composition of near-future wastes (Daskalopoulos et al., 1998;Zaman, 2014).This, coupled with the global pressure to handle the green agenda, at the expense of the brown agenda (Shrestha, 2019), frustrates SWM efforts in the Global South via imbalances in funding opportunities and affordability within regions, as the global issues take precedence over local environmental concerns.
Stakeholder inclusion.Figure 4 illustrates key stakeholders in SWM systems and processes (Ezeah et al., 2013).A successful and sustainable SWM system has active stakeholders in the entire process including planning, design, and other decisionmaking activities (Okot-Okumu & Nyenje, 2011;Schübeler et al., 1996).Whereas stakeholders, including formal and informal waste service providers, enablers, and users, exist across countries, the extent to which they are included in decision-making varies (Fuss et al., 2018;Yukalang et al., 2018).In some countries, there exists limited engagement between the public sector and service users (citizens), which may hinder behavioral change and reduce SWM productivity and effectiveness (O'Connor et al., 2019).Most informal service providers are also rarely integrated within the formal SWM system structures (Matter et al., 2015).Because urban councils may not have legal mandates to supervise or enforce regulations on such activities, the informal stakeholders often render unauthorized, unplanned, unsupervised, and sometimes legally unrecognized waste services (Hoornweg & Bhada-Tata, 2012;Oteng-Ababio et al., 2013).
Several countries, however, have involved the informal economy through active politics, stakeholder platforms, and unions (Hoornweg & Bhada-Tata, 2012;Oguntoyinbo, 2012).In Malaysia, Nepal, and Tanzania, long-term plans were established for community inclusion within the SWM systems (Okot-Okumu & Nyenje, 2011).In Malaysia, a direct, active, and strong social link between waste service users and managers was established to assess the performance of private service providers (Guerrero et al., 2013).In Nepal, municipalities formed stakeholder committees, headed by local personnel, to regularly monitor and contribute to the management of local landfills (Wilson et al., 2006;Wilson et al., 2013).In 2000, Tanzania (via the Moshi community) initiated a decentralization policy and formed a stakeholder platform that enhanced engagement and participation in the planning and operation of SWM services (Khamis, 2016).Egypt (Cairo) achieved a 40%-50% waste separation and collection rate after the privatization of the SWM system and the formation of an 80% informal economy group (Zabaleen) to collect, recycle, and treat waste (Ezeah et al., 2013;Jaligot et al., 2016).Upon the registration and incorporation of its informal economy into the national SWM structure, Brazil established a plastic and aluminum recycling plant and became a global producer of aluminum cans (Beatriz et al., 2014;Ezeah et al., 2013).In China, 3.3-5.6 million people are informal recyclers (Yang et al., 2018).In China (Beijing) and Vietnam (Ho Chi Minh City), more than 200 000 and 16 000 registered active waste pickers exist, respectively (Kaza et al., 2018).In Nigeria (Lagos), scrap dealers were formally recognized, and they can operate legally (Egun, 2017;Oguntoyinbo, 2012).Major cities in India (Pune) and Latin America have registered, licensed, and integrated informal waste collectors into cooperatives, granting them access to waste in selected areas (Oguntoyinbo, 2012).In Peru, the municipal authorities integrated informal waste pickers into the formal systems (Marello & Helwege, 2018); in Argentina (Buenos Aires), these groups are registered and allowed to remove recyclable materials from the community curbside bins (Kaza et al., 2018).At the Baruni disposal facility (Papua New Guinea), informal waste services are registered and formalized; however, at a disposal site in Vanuatu (Port Vila), the waste pickers must be registered to have access to waste collection (Kaza et al., 2018).
On the contrary, compared with similar services offered by the urban councils in many countries, the formal private sectors (i.e., NGOs and community-based organizations [CBOs]) have served more than half the poor urban population and greatly improved waste awareness across communities (Okot-Okumu, 2012;Okot-Okumu & Nyenje, 2011;Oteng-Ababio et al., 2013) as well as collection, recycling, and disposal (Ezeah et al., 2013;Ma & Hipel, 2016).For example, in Bangladesh (Dhaka) and India (Delhi), the local NGOs work with urban authorities to supplement existing informal economies (Ezeah et al., 2013;Ma & Hipel, 2016;Wilson et al., 2013).In India (Madras), the NGO EXNORA created a waste collection program, where low-income residents pay small fees to receive the service (Aparcana, 2017;Ezeah et al., 2013).In Brazil, a community organization (COOPAMARE) collects and sells approximately 100 tons of recyclable materials monthly (Ezeah et al., 2013;Gutberlet, 2021).In South Africa, CBOs, cooperatives, and associations are established or supported by NGOs to engage in recycling projects as livelihood opportunities (Ezeah et al., 2013).In Mali (Bamako), Brazil (Belo, Horizonte), India (Bengaluru), and the Philippines (Quezon City), waste users formed platforms for communication and consultation during strategic planning, siting of facilities, and in the organization of day-to-day waste services; they have also created platforms to institutionalize inclusivity in the formal SWM systems (Beatriz et al., 2014;Ezeah et al., 2013;Widmer et al., 2005;Wilson et al., 2013).In Ghana (Kumasi, Tema, and Accra), several informal stakeholders were incorporated into plastic picking, collection, sorting, and selling, forming a model recycling practice (Obeng-Odoom, 2014;Oteng-Ababio et al., 2017).In Zambia (Lusaka), more than 30% waste collection coverage is provided by the informal economy (Aparcana, 2017;Ma & Hipel, 2016); in Uganda, the urban councils have contracted the private sector in waste collection and disposal services (Okot-Okumu & Nyenje, 2011).More notably, the involvement of all stakeholders in the planning and implementation of SWM processes makes the systems more sustainable and responsive to local conditions, needs, and expectations.Stakeholder engagement and inclusion during design and implementation also encourages behavioral changes and supports the reduction in environmental and health risks (O'Connor et al., 2019).The integration of the informal economy into formal SWM structures through registered associations, cooperatives, or private partnerships (community environmental groups and properly licensed microenterprises) empowers access to data, funds, and technical and management skills, as well as supporting enforcement and reducing operational conflicts (Matter et al., 2015).Thus, using the local and nationwide public education strategies (e.g., media, trade unions, and corporate organizations) supports WH compliance and enhances stakeholder awareness and participation (Debrah et al., 2021).

Waste management practices
Ideally, sustainable SWM approaches follow WH concepts (Figure 2; Kaza et al., 2018).Countries aiming at achieving either less or even zero waste (Hoornweg & Bhada-Tata, 2012) have implemented WH practices, including 100% recycling and/or 100% recovery (Zaman & Lehmann, 2011), significantly reducing landfill deposition (Shekdar, 2009;Zink & Geyer, 2019).Countries treating "waste" materials as resources (Zaman, 2015) have adopted CE systems and promoted behavioral changes to rethink, avoid, reduce, reuse, recycle, repair, recover and/or redesign, and remanufacture (Ghisellini & Ulgiati, 2020;Kaza et al., 2018;Zaman, 2014).Despite that, not all SWM policies, strategies, and practices developed in the Global North are easily implementable in the Global South.Thus, there are higher recycling and relatively lower dumping rates in the developed world than the developing world (Figure 5).However, many countries in the Global North still generate vast quantities of waste and depend on waste practices located at the lower tiers of the WH, including incineration, landfilling, and open dumping (Roy & Tarafdar, 2022).Although SWM WH practices in the Global North and South are comparable (Figure 2), their environmental and human health impacts depend on both local approaches, infrastructure, and larger drivers such as CE aspects and global trade issues (Talang & Sirivithayapakorn, 2021).Regardless of an increasing focus on CE concepts, SWM challenges remain across countries.Solid waste management approaches should be selected based on waste form, composition, quantity, and local needs and conditions (Marshall & Farahbakhsh, 2013).
Waste generation and separation.Globally, waste generation is influenced by composition (Wilson et al., 2013), industrialization, urbanization, population size, education level, public habits, and intention (Zaikova et al., 2022), household attitudes, age groups, local climate, consumption, behavior, and culture (Moh, 2017), land size, household location (rural/urban), economic status, and monthly income (Triguero et al., 2016;Zaman, 2015;Zaman & Lehmann, 2011).Generally, higher economic status comes with greater disposable income and consumption, and higher waste generation (Abagale et al., 2012;Roy & Tarafdar, 2022).Therefore, average waste generation per capita in the Global North is greater than in the Global South (Table 1) and affirms that, in both, more production as well as waste separation and recycling challenges are expected in the coming years (Kaza et al., 2018;Kawai & Tasaki, 2016).Despite this, the relative increase in waste generation (volumes) is projected to be greater in the Global South, especially if WH principles and CE concepts for sustainable SWM strategies and practices are not adhered to (Hoornweg & Bhada-Tata, 2012).Although the Global North has tried to reduce waste generation through enhanced WH compliance and increased technologies for recycling (Ezeah et al., 2013), unmanaged industrialization in the Global South continues to cause rural-urban migration, population increase, slum development, and increased waste generation (Kawai & Tasaki, 2016;Saha, 2013).Enhancing knowledge of waste risks and benefits (Rebehy et al., 2017), new technologies, user willingness to pay for waste services, public habits (Ong & Sovacool, 2012) and engagement (O'Connor et al., 2019), gender perspective (Oztekin et al., 2017), peer influence, increased coverage, regulations on collection and landfill fees, and landfill material bans could reduce waste generation (Guerrero et al., 2013;Wilson et al., 2013).
During separation, waste is divided into reusable, recyclable, compostable, and incinerable materials, reducing collection, treatment, or disposal volumes (Abagale et al., 2012;Oguntoyinbo, 2012).This practice promotes zero-waste strategies because it reduces leachate-forming materials to landfills, and minimizes landfill taxes, banned materials and green house gases (GHG) emissions (Egun, 2017;Moloney & Doolan, 2016).Waste separation information helps city planners and policymakers to devise future SWM strategies, including choosing treatment, operation, and maintenance technologies (Fauziah et al., 2009;Wilson et al., 2013).In many Global North countries, waste separation is a formal and mandatory practice, done manually in households and at curbside centers, and automated with mechanical and biological treatment systems at material recovery facilities (Bergeron, 2016;Ezeah et al., 2013;Shekdar, 2009).To promote household and community waste separation practice, regulations and social influence were applied to change personal attitudes and public perspectives from a throw-away society to a more environmentally friendly society (Bai & Sutanto, 2002;Zaman & Lehmann, 2011).
Despite SWM improvements, many countries in both the Global North and South are still noncompliant with WH principles and CE concepts (Rodic et al., 2010;Zaman, 2015), with persistently high waste generation, incineration, landfill, and open dump disposal volumes (Guerrero et al., 2013;Hoornweg & Bhada-Tata, 2012;Kawai & Tasaki, 2016;Wilson et al., 2013).In the Global South, the informal economy, often not included in the formal SWM systems, are the key active players in waste separation practice (Okot-Okumu & Nyenje, 2011).Without legal mandate and guidelines, enforcement by government authorities on this group is impossible (Beatriz et al., 2014;Diaz, 2011;Liyala, 2011).Financial constraints may also hinder waste separation; thus, available government services concentrate only on removing waste nuisance from the public domain (Egun, 2017;Oguntoyinbo, 2012).Waste separation rates are also influenced by manual strategies at collection and transit points, waste type and status, climate, distance, and frequency of bin collection (Okot-Okumu, 2012;Oteng-Ababio et al., 2013).Despite contributions from the informal economy, the quality of recyclable materials, low demand (Wilson et al., 2013) and enforcement, limited international collaborations and markets, and price fluctuations in local and global markets have frustrated efforts to increase separation and recycling (Gunarathne et al., 2019;Okot-Okumu & Nyenje, 2011).Monitoring individual waste generation volumes and separation practices in high-rise apartments that use single communal collection skips is also challenging (Xiao & Siu, 2018).This, in addition to adopted technologies (e.g., waste trucks) designed for cooler climates (e.g., to compact inorganic wastes; Schübeler et al., 1996), creates more separation and management challenges for Global South countries, with high organic waste content (Gourmelon, 2015;Ma & Hipel, 2016;Thompson et al., 2009).Such obstacles increase waste generation and management costs, posing greater risks for many countries in the Global South (Ejaz et al., 2010;World Bank, 2012).
In the Global North, waste collection services are often government regulated and centrally controlled (Bai & Sutanto, 2002;Kaza et al., 2018).This has supported timely budget allocation, intermediary waste processes, mechanization, and reduced handling challenges during collection, storage, transfer, and disposal (Hoornweg & Bhada-Tata, 2012;Wilson et al., 2006).In building sustainable SWM systems, collaborative interaction among stakeholders must inspire confidence, build trust, and improve accountability and transparency (Ezeah et al., 2013;Okot-Okumu & Nyenje, 2011).Waste collection fees are charged after dialogue with service users-with calculations based on costs incurred and allocated as either a property tax or a levy (Kaza et al., 2018;Ma & Hipel, 2016).For privately contracted and licensed service providers, municipalities and/or responsible departments decide on collection fees, designate collection areas, and monitor service levels (Bai & Sutanto, 2002).This reduces corruption and political influence, and improves collection coverage, efficiency, and service provision levels (Gumisiriza & Kugonza, 2020;Ma & Hipel, 2016;Romano et al., 2021).
In Singapore, waste collection was privatized, 350 contractors were licensed, the road network was improved, and a fleet of large-capacity trucks and site-appropriate waste collection systems were introduced (Bai & Sutanto, 2002).In high-income and socialist countries (e.g., China), citizens have 100% waste collection coverage, and receive services irrespective of their social status (Bai & Sutanto, 2002;Chu et al., 2019;Kaza et al., 2018).In Australia (Canberra), household garbage and curbside collection bins, weekly collection calendars, recycling, and online waste apps such as Australian Capital Territory (ACT) sustainable schools program were introduced (ACT Government, 2023).However, not all municipalities or states, even in the Global North, have effective SWM systems (Bernardo et al., 2023).
For instance, in Queensland and some rural Australian states, SWM systems are inadequate (Salim et al., 2023), whereas on the outskirts of the national capital city, Canberra, only two to three color-coded bins are provided.Such communities exhibit mixed and contaminated waste (Bernardo et al., 2023), creating obstacles during separation as well as increasing landfill and incineration volumes, environmental impacts, and health risks (Zaman, 2015;Zaman & Lehmann, 2011).
Collection, storage, and transfer across borders: Waste trading.Many countries in the Global North and some in the Global South (e.g., China) practice waste trading, the international (or cross-regional) transfer of waste for further treatment, disposal, recycling, or technical aid (Liu et al., 2018;Zaman, 2014).This practice is part of the "collection, storage and transfer" step in Figure 2, where waste, generated in one area is transferred, treated, recycled, or disposed of in another area (Hanfman, 2012;Vidal, 2013).Waste trading can help a constituency meet local waste regulations and targets, preserve local areas for other purposes, or save money by avoiding landfill taxes, recycling charges, or landfill material bans, such as those for electronics (Lamb et al., 2014;Sidique et al., 2010;Stegmann, 2017).Internationally, Europe, Australia, Japan, and the USA trade their electronic waste (e-waste) products in Latin America and China (Ezeah et al., 2013;Ongondo et al., 2011;Patil & Ramakrishna, 2020).The USA, European countries, Russia, Japan, Italy, and China export waste to West and East Africa (Cotta, 2020;Kiddee et al., 2013;Widmer et al., 2005).However, once transferred, the waste generators no longer have control over and are not affected by further management practices.For example, in Australia, ABC's 4 Corners program reported on the transportation of mixed waste from New South Wales and its illegal disposal in Southeast Queensland (Lasker et al., 2017).Similarly, before China's 2018 recyclables ban, Australia exported 4 million tons of recyclable materials, of which 1.3 million tons went to China (Bernardo et al., 2023;Lasker et al., 2017;Downes & Dominish, 2018).However, to protect the Chinese environment and public health, China's 2018 waste import ban set restrictions on maximum contamination thresholds and limited the number of imports permits for 24 contaminant solid waste streams.
Considering the post-trading life cycle of plastics, these products may end up in open dumps, oceans (Nicholls et al., 2021;Vince & Hardesty, 2017), or buried as plastic waste, contributing to the global plastic volume: 10%-20% in landfills and 22%-43% in oceans (Beatriz et al., 2014;Gourmelon, 2015).Waste, including vast volumes of plastics and electronics, are diverted to other countries, increasing pressure on the already stressed infrastructure in the "lowerincome countries, awash in the trash of wealthy nations" (GAIA, 2019;Vince & Hardesty, 2017).Obeng-Odoom (2013) states that the plastic waste pandemic is closely related to the general sanitation crisis in most cities, with vast literature pointing to the negative environmental and social problems from their poor management.He further emphasizes that some plastic containers, when exposed to heat, produce dioxin, a highly poisonous, cancer-causing chemical, and yet others are nonbiodegradable, and stay for years in the environment.
Many countries in the Global North have policies and frameworks on toxic products and material disposal, but those in the Global South lack, for instance, e-waste management frameworks and disposal guidelines (Bai & Sutanto, 2002;Ejaz et al., 2010;Shittu et al., 2021).The continued import of new and used poor-quality consumer products to the Global South results from the countries' inadequate policies and weak enforcement (Nnorom & Osibanjo, 2008;Ongondo et al., 2011).A lack of clear management mechanisms for large stockpiles of hazardous e-waste, the limited number of formal e-waste recyclers and managers, and the scarce data on proper disposal further increase environmental impacts and health risks in some urban communities (Aydin, 2017).Kenya, however, has developed formal guidelines for the informal SWM economy (Blaser & Schluep, 2012;Wasswa & Schluep, 2008), and Rwanda has very strong proactive municipal SWM policies (Kabera et al., 2019).
Neoliberal economic theory argues that there is sound economic logic in dumping (toxic) waste in the Global South countries as part of development policy, and as a logical outcome of market forces (Courard-Hauri & Lauer, 2012).Such trade has recently focused on opportunities for recipients to extract resources from waste as recyclable components and used goods to create income-generating opportunities, possibly reducing the environmental burdens (Cotta, 2020).This notion was supported by Obeng-Odoom (2014), who reported that the neoliberal system encourages and supports corporate recycling because of low cost and employment opportunities to the poor.However, circumstances including financial difficulties, environmental inadequacies, and challenging relations with authorities pose risks.When the receiving countries do not have the resources to manage traded wastes safely, their processing and disposal contribute to environmental and health risks that affect populations across the Global North and South (Zaman, 2014).Shamim et al. (2015), Rucevska et al. (2015), Arya and Kumar (2020), Cotta (2020), and Walters and Fuentes Loureiro (2020) reported that exports of used electronic equipment and recyclable plastic materials exacerbate the environmental burdens in the Global South, while also exporting new environmental risks and social burdens, leading to calls for justice and the adoption of new international measures.
Previously, plastic wastes were largely outside the scope of the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal (Choksi, 2001;Widmer et al., 2005).However, in 2019 the treaty was amended to explicitly bring most plastic waste within the category of wastes controlled as "hazardous waste," or "waste requiring special consideration" (Khan, 2020).However, implementation and enforcement will remain challenging due to transnational, legal, regulatory, and economic disparities, unless financial and environmental responsibility for plastic waste is placed within the product supply chain (Khan, 2020).The EU has a growing focus on circularity in its Circular Economy Action Plan, but Kettunen et al. (2019) has observed that an increased framing in which recyclable waste becomes a traded good has led to the phenomenon of "waste dumping."Thus, they recommend a range of national, regional, and international standards and policies to ensure that European green objectives do not merely export impacts elsewhere.There is compelling evidence that the waste trade can be driven by the avoidance of environmental regulation.Kellenberg (2012) evaluated bilateral waste trade data and an index of environmental stringency for 92 countries and concluded that waste imports increase for a country whose environmental regulations deteriorate vis-á-vis its trading partner, and that differences in environmental standards can play an important role in international waste trade flows.
Waste trafficking, the illegal export and/or illicit disposal of e-waste, plastics, and hazardous substances, generates an estimated USD 10-12 billion annually (FATF, 2021).Coming from North America and Western Europe, waste is trafficked primarily to sub-Saharan Africa, Southeast Asia, and Central and South America, with criminal syndicates playing a significant role.This waste has a negative value at its destination, causing economic, social, and environmental impacts (FATF, 2021).Clearly, waste trading, legal and illegal, will continue for some time.Meanwhile, past and current impacts and risks from poor SWM strategies and practices should be urgently tackled to equitably protect the environment and associated human health consequences (Bras et al., 2009;Hanfman, 2012;Stegmann, 2017).
Recycling.Recycling converts used material into new products, reduces landfill volumes, and lowers consumption of fresh raw materials, energy use, GHG emissions, and risks (Saha, 2013;Sidique et al., 2010).Recyclable materials include glass, paper, metals, tires, plastics, textiles, electronics, aluminum (e.g., cell phones, computers), and concrete aggregates from demolition sites (Ezeah et al., 2013;Guerrero et al., 2013).The formal adoption of best practices and zerowaste policies by some nations in the Global North such as Sweden, Germany, Austria, the Netherlands (Rotterdam), Singapore, the USA (San Francisco, California), Canada (Vancouver), and Australia (Adelaide) have resulted in a relatively high recycling rates and almost zero landfill deposition (Halfman, 2009;Marshall & Farahbakhsh, 2013;Wilson et al., 2013;Zaman, 2015).Many such countries have invested in recyclable material collection services and high-technology sorting and processing facilities (Ezeah et al., 2013).On a nationwide basis, the Singaporean waste reduction department developed, promoted, and explicitly implemented a free waste audit program (Zhang, Keat, et al., 2010) and worked closely with the business community on customer material, product packaging, and green labeling schemes to minimize waste (Bai & Sutanto, 2002).In the Global South, Egypt (Cairo) stands out with a recycling rate of approximately 80% (Hemidat et al., 2022).
To address such challenges, Brazil incorporated the informal economy into the formal waste structure, provided technologies for the recovery process, regulated recycling prices, provided incentives, and considered green procurement for environmentally sustainable consumption (Beatriz et al., 2014).In 2013, China created a recycling ministry with resource management as an economic activity, transitioned its economy from communist to market-based, and opened its borders to international trade (Ezeah et al., 2013;Guerrero et al., 2013).In 2018, the Chinese government placed a ban on international waste trading to reduce the number of contaminated materials entering the country, to promote more local recycling, to protect the environment, and to establish links between the circular use of resources and materials in industrial production and everyday life.
SWM challenges in many countries partially result from the lack of stakeholder awareness, inclusion and participation (Singh et al., 2022).In the Global South, public education campaigns often emphasize environmental eductaion rather than material recovery, and recycling is not governmentregulated but market-driven, focusing on private sector interests (Egun, 2017;Oguntoyinbo, 2012).Limited technologies and inadequate training affect technical skills, whereas scarce government incentives, lack of access to recycling depots, unreliable markets for recycled products, and material price fluctuations demotivate and limit stakeholder participation (Lederer et al., 2017;Moloney & Doolan, 2016).Coupled with the limited inclusion of informal economy, including recyclers, within the formal SWM structures (Beatriz et al., 2014), limited technologies and inadequate training creates a hinderance to technical skills, while scarce government incentives (Ndejjo et al., 2019) and access resources (loans) from the government (Ezeah et al., 2013).Worldwide, equipment and infrastructure inefficiency, unregulated waste collection and separation methods, and unstable recyclable material supply hinder waste quality, quantity, and recycling rates (Aydin, 2017;Guerrero et al., 2013;Sarptaş & Erdin, 2015).Consequently, the local and global market requirements for recyclable quality and quantity may not be met (Bergeron, 2016;Egun, 2017;Oguntoyinbo, 2012).
In the Global South, many nations generate 60%-80% organic waste composition, resulting from fresh fruit, vegetable, and other food content (Ahmadifar et al., 2016;Okot-Okumu & Nyenje, 2011).Nevertheless, composting practice is still underutilized because of limited expertise and awareness of the benefits, as well as inadequate markets, resulting in mixed waste generation, poor quality compost (Ding et al., 2021;Khan et al., 2022;Okot-Okumu & Nyenje, 2011), and other risks (Cestonaro et al., 2022).Yesaya et al. (2021), reported that in Malawi, green waste is contaminated with plastics, and it takes 1 h and 50 min of active labor time to sort and produce a 165 L (0.065 m 3 ) bag of compost; thus, capital and operating costs render the practice cost-ineffective and unsustainable.
Still, some small communities, well-to-do homes, and farms in the Global South have benefited from composting, generating animal feed, agricultural manure, and domestic biogas (Wilson et al., 2013).In Mali, resource and nutrient value is recovered, either as raw material or as partly decomposed waste and sold to grain and vegetable farmers (Wilson et al., 2013).A decade ago, under EU Carbon-Development Mechanisms funding, Uganda, China (Kunming), and Brazil (Belo) built composting pilot projects to evaluate the capacity of individual countries to generate compost (Wilson et al., 2013).However, the current composting rates are 3% for China (Ding et al., 2021;Khan et al., 2022), 5% for Brazil (Liikanen et al., 2018), and restricted use class RU-1 (low fertilizing capacity and poor quality) reported for Uganda (Kabasiita et al., 2022).This aligns with the notion that fewer implementations of Global Environment Facility and World Bank financed low-carbon projects including in waste management and climate mitigation action in the Global South nations are influenced by limited stakeholder awareness and inclusion (Lederer et al., 2017), lower institutional capacity (Adenle et al., 2017), and key policy instruments (Kameyama et al., 2016); therefore, it is necessary to involve key actors in the entire process design and establish strategies at regional and national levels.
Recovery: Incineration.Incineration is a thermal waste reduction and recovery practice at the lower tier of the WH (Zaman, 2015).Incineration reduces landfill-banned materials, waste volumes, and disposal taxes; however, it also generates GHG and requires landfills to dispose of toxic and caustic fly/bottom ash (Aracil et al., 2017;Rigamonti, 2004).In Sweden, incineration produces electricity, steam, and heat to warm houses during winter (Karlsson et al., 2018), thus saving on energy costs (Zaman & Lehmann, 2011).Norway, Italy, Ireland, and the UK send more than 800 000 tons/year of waste to Sweden (i.e., waste trading), for incineration to reduce landfill volumes and avoid disposal taxes (Stegmann, 2017;Watson, 2013).Due to limited space, Singapore, an island, incinerates its waste to generate electricity, uses pollution control systems to recover metal scraps (Bai & Sutanto, 2002;Zhang, Keat, et al., 2010), and aims to use source-separated food waste and brown water as potential future waste-to-energy options (Tong et al., 2018).
In many Global South countries, incineration was initially introduced during colonial days to treat hospital waste (Okot-Okumu & Nyenje, 2011).Given their age, most incinerators lack stack monitoring and pollution control systems, and, thus, their emissions pose ecological and human health risks (Bras et al., 2009;Oteng-Ababio et al., 2013).The high inert and organic materials and enormous moisture content from the generated waste limit the efficacy of incineration as a waste reduction strategy (Ahmadifar et al., 2016;Moloney & Doolan, 2016).However, some nations have initiated strategies to deal with the associated challenges.In the Philippines, incineration was banned via the Clean Air Act 1999, but cement industries applying this practice are monitored under the Ecological Solid Waste Management Act 2000 (Sapuay, 2016).Bangladesh (2002) and India (Maharashtra) banned the manufacture, sale, and use of plastic bags whose treatment (via incineration: controlled burning, with chimneys to extra toxic gases) and disposal (via burning: most cases has been in open areas) would have contaminated the air (Chowdhury et al., 2021;Marshall & Farahbakhsh, 2013;Wilson et al., 2013).However, Chowdhury et al. (2021) points out that, despite the ban, plastic bags are still widely used in Bangladesh because of limited enforcement, created by the disconnect in knowledge and capacity to understand the associated environmental and public health crisis.Thus, the feasibility and sustainability of waste management processes, including incineration, depend on stakeholder awareness of risks and benefits, local infrastructure, good governance, and available resources.
Recovery: Waste mining.In many places, the informal sector, including vulnerable children, youth, and women, have resorted to waste mining to extract and recover salable or reusable materials, driving demand for scrap metal and other waste mineral resources (Obeng-Odoom, 2018).Mining metals from society's waste reduces the need for the import of primary resources, offsets waste disposal costs, conserves space in landfills, and limits the spread of potentially harmful metals into the environment, thus supporting a sustainable society (Smith et al., 2015).In the USA, gold, silver, platinum, copper, lead, zinc, indium, tellurium, rare earth elements, and other precious and industrial metals have been mined from biosolids or sewage sludge (Smith et al., 2015).Other aspects, concerns, and strategies regarding the informal sector have been discussed under the section on recycling.
As with incineration, open burning is a thermal waste reduction strategy often practiced on open dumps and applied commonly because of its low cost and land space requirements (Okot-Okumu & Nyenje, 2011).However, in the absence of pollution control devices, open burning contributes to severe air pollution (Wilson et al., 2013) generating GHGs, hexachlorobenzene, dioxins, carbon monoxide, particulate matter, volatile organic compounds, and ash (Abagale et al., 2012;Zhang et al., 2017).Open burning oxidizes metals from electronic wastes, generating ash with a mixture of chemicals.Ash can be collected and buried in landfills but, where resources are limited, the material is often disposed of in open areas, posing ecological and human health risks.
Illegal and uncontrolled dumping, often known as "fly-tipping," still occurs internationally, driven by criminal syndicates (FATF, 2021), but also by a desire to avoid tipping fees or merely because of laziness (Smith, 2020).An extreme example is the "Triangle of Death" in Italy (Sicily) where cancer, child mortality, and birth defects were linked to illegal waste dumping practices (Triassi et al., 2015).In England, the local authorities dealt with more than 1 million fly-tipping incidents in the 2018-2019 fiscal year, an increase of 8% over the previous year, with nearly two-thirds from household waste (Smith, 2020).Flytipping in 2015 is estimated to have cost England approximately £209 million, about a third of the waste crime costs for that year (HMG, 2018).
A similar but more expensive waste disposal practice is landfilling.Although at the bottom of the WH (Figure 2), landfilling is extensively applied in both the Global North and South.Landfilling rates continue to be high; for example, in Australia (70%; Smith et al., 2012), Israel (90%), New Zealand (85%), Ireland (66%), the USA (54%; Mukherjee et al., 2020), and Greece (92%; Hoornweg & Bhada-Tata, 2012;Showers & Chewning, 1994).Although some landfills have liners, leak detection, leachate and gas collection and treatment systems (Abagale et al., 2012), many do not; the types, age, and design of landfills determine the extent of leachate leaks and GHG emissions and the nature of impacts and risks.
Landfill management and control efforts include reducing or phasing out landfills or open dumps.Landfill use in the UK has dropped from 80% in 2001 to 43% in 2013; the number of formal and active landfill sites fell from 1700 in 2002 to 725 in 2012 (Watson, 2013).Italy reduced landfill use from 72% in 2000 to 48% in 2010, active landfills, from 657 to 401, and increased recycling rates from 12% in 2001 to 23% in 2010 (Rigamonti, 2004;Watson, 2013).Through postclosure strategies and private sector involvement in SWM processes, the USA and Greece are reducing landfill use and illegal dumping (Wilson et al., 2013).Australia, with a 70% disposal rate, uses phytocapping technology for landfill remediation, a practice that involves placing a barrier to reduce GHG emissions and water percolation (Moloney & Doolan, 2016;Smith et al., 2012).According to Bai and Sutanto (2002) and Balakrishnan (2016), Singapore uses landfills to treat incinerated bottom waste and replants mangrove trees to capture GHGs (methane, carbon dioxide) and treat leachate before disposal.
Despite the health hazards from open dumps and landfills, these practices remain the only low-cost waste treatment options in much of the world.In the Global South, some nations are either phasing out or are struggling to upgrade open dumps to controlled dumps or sanitary landfills with leachate and gas control systems (Beatriz et al., 2014;Okot-Okumu & Nyenje, 2011).The acquisition of a modern landfill is acknowledged as an advancement in SWM strategies (Oguntoyinbo, 2012;Sarptaş & Erdin, 2015).For example, in Morocco, landfill deposition rates have increased from 10% in 2008 to 80% in 2018 (Kaza et al., 2018) and, of all the East African municipalities, only Kampala (Uganda) owns an engineered disposal site (Kabera et al., 2019).In comparison, Zambia (Lusaka), Kenya (Nairobi), Nicaragua (Managua), and India (Dhaka) have constructed engineered landfills and use mixed traditional and modern waste approaches in waste collection and regulation of informal activities (Wilson et al., 2013).
Increasing public awareness, inclusion, and participation have supported collective action in other nations.A strong protest from the citizens of Mumbai and Delhi (India) led to the closure of existing open dumpsites (Wilson et al., 2013); in Brazil, unregulated dumping sites and landfills were deactivated (Beatriz et al., 2014).In Slovakia, the Trash Out project allows the public to report and provide information to authorities on the location and status of illegal dumps through mobile apps (Šedová, 2016).For Nepal, the country used a participatory approach to construct and operate a modern landfill, without foreign aid (Wilson et al., 2013).Still, much of the Global South faces a range of issues, many of them country-or region-specific, which makes achieving sustainable SWM challenging.Therefore, waste crimes are an international challenge, whether the waste is dumped locally or traded across borders.

CONCLUSIONS AND RECOMMENDATIONS
The implementation of WH concepts in SWM can be observed to some extent in most Global North countries, with many Global South nations predominantly applying the reuse concept and other aspects of the WH to varying extents.Some countries have successfully achieved zero waste, zero landfilling, and other sustainable SWM strategies; these can, with the appropriate policy, funding, infrastructure, and stakeholder awareness, be applicable globally.On a global scale, however, both Global North and South implementation of the WH leaves much to be desired, given several global and region-specific SWM challenges.Everincreasing waste generation; legal and illegal open dumping, stockpiling, and waste trading; controlled and "backyard" incineration; and still-significant landfill disposal remain common practices in both the Global North and South.The resulting environmental and health impacts are indicators of globally unsustainable production, consumption, and SWM practices (Hoornweg & Bhada-Tata, 2012;Kaza et al., 2018).
Sustainable SWM depends on complex and expensive technologies, economic tools, regulatory frameworks (taxes, fines, incentives), social awareness and pressure, and inclusion and participation of all relevant stakeholders (actors).Globally, disparities can be attributed to differences in financial and institutional resources for waste treatment and disposal methods, economic status, social habits, and degrees of stakeholder awareness of waste risks and benefits, inclusion, and participation.Public engagement and successful implementation of SWM require a focus on local needs and conditions, waste education, research, and onthe-job training.Where education is primarily theoretical and sanitation-based, regions may lack the local technical capacity to maintain, monitor, and manage sustainable SWM systems.Where government regulations, guidelines, and enforcement are weak or lacking, or proactive policies (e.g., the political will to fund) are limited, SWM processes suffer.Political interference, lack of democratic structures and long-term commitments, corruption, inadequate accountability, and poor transparency all create barriers to informed decision-making in support of effective SWM, environmental protection, and pollution control systems.
Enforcement of zero-waste concepts across all countries is needed to reduce generated waste, incineration and landfill volumes, environmental impacts, and health risks.Recyclable waste drop-off and buy-back centers are required.These must provide adequate, standardized storage and collection facilities to reduce mixed waste streams and promote separation practices and individual generation monitoring.To support this, a strong domestic market for recyclable materials is required.
Environmental protection and public health policies should be science-based; this requires investment in monitoring, research, and innovation that is region-specific and appropriate, affordable, and relevant to local needs.Comprehensive and reliable global contaminant research, monitoring, and data are also needed.Increased monitoring of chemical exposure from past and current waste contaminated sites (e.g., Awino et al., 2020) should be supported.
Examples of effective strategies and practices, as well as manuals and guidance, should be developed to strengthen implementation capacities internationally.Countries and regions should be supported in designing and implementing low-cost SWM strategies and technologies, appropriate to local needs and conditions, which are easy to operate and maintain, seeking to optimize practices, frequency, and coverage.
Sustainable systems require adequate and equitable analytical facilities, reliable data on waste generation and composition, and environmental monitoring to evaluate the impacts and risks and support technological innovation, planning, and management at grass root levels.Where regions depend on donors to fund their SWM systems, there should be a focus on locally appropriate (rather than simply exported) tools, frameworks, expertise, and equipment, and a commitment to ensuring stable funding for longer term monitoring, operations, maintenance, and adaptation.
Even where WH principles are applied, SWM will continue to challenge all regions, driving resource depletion and increasing waste generation unless CE concepts are integrated.Thus far, waste separation programs in many Global South nations, generally involving informal stakeholder participation, have focused on the economic benefits of retrieved recyclable materials, often at the cost of environmental and human health.Problems are exacerbated when Global North countries, seeking to reduce costs or meet their own policy and CE objectives, trade poorly or incorrectly classified wastes to countries less able to control impacts during recycling.Unsustainable strategies and practices from the Global North, including waste trading, continue to contribute to waste impacts and risks in the Global South.
Industries involved in product design and reuse should be provided with incentives and infrastructure, whereas producer responsibility laws should be enacted and enforced to ensure that there are consequences (e.g., fines or taxes) for bad practices.There is a need for global initiatives to address consumer products, to understand chemical safety issues throughout life cycles, to develop adequate legal frameworks (including chemical waste management and risk assessment frameworks) for medical, industrial, and e-waste in the Global South, regardless of where it is produced, consumed, or disposed.Extended producer responsibility tools should be applied to ensure product stewardship and protection of the environment.
Waste impacts and risks are global and cross-border; collaborative actions between the Global North and South are urgently needed to combat the past and present SWM challenges and to achieve sustainable solutions that equitably address both the green and brown agenda across nations.

ACKNOWLEDGMENT
Florence Barbara Awino appreciates Professor Bill Maher and Dr. Jasmyn Lynch from the Institute for Applied Ecology, University of Canberra, for their general support in guiding the initial conceptualization of this article.The authors appreciate Dr. John Toll, Windward Environmental LLC, for his initial editorial support and guidance.This project was supported by Schlumberger Faculty for the Future Scholarships (2015-2019).Nevertheless, they did not influence the study design, data collection, analysis, data interpretation, writing, and/or the decision to submit this article to the journal.Open access publishing facilitated by University of Canberra, as part of the Wiley -University of Canberra agreement via the Council of Australian University Librarians.

DISCLAIMER
The peer review for this article was managed by the Editorial Board without the involvement of Sabine E. Apitz.

TABLE 1
Annual waste generation rates (in billions of tons/years and kg/day per capita) across economic development groups; historical and projected values