Waste management--still a global challenge in the 21st century: An evidence-based call for action

A critical review and analysis of plastic waste management practices in Rwanda

Plastic products are now essential commodities, yet their widespread disposal leads to environmental and human health effects, particularly in developing nations. Therefore, developing nations require comprehensive studies to assess the current state of plastic and plastic waste production to enhance plastic waste management practices. This review analyzes the import and export of plastic and the production of plastic waste in Rwanda, aiming to improve waste management practices. This review used open-access papers, reports, and websites dealing with plastic waste management. In this review, 58 articles from the Web of Science and 86 from other search engines were consulted to write this review. The findings revealed that the daily estimated plastic waste produced per person ranges between 0.012 and 0.056 kg. The estimated amount of plastic waste generated per person per year in Rwanda could be between 4.38 and 20.44 kg. Plastic waste accounts for between 1 and 8% of the total municipal solid waste produced per person per day in the country, which ranges from 219 to 255.5 kg. The average annual amount of imported plastics could reach 568.2881 tons, whereas the average quantity of exported plastics could reach 103.7414 tons. This shows that plastic management practices have not yet adopted technically advanced or improved practices, which should concern efforts to protect our environment. This study suggests approaches that can vastly improve plastic waste management and potentially open massive opportunities for the people of Rwanda.

Integration of Digestate-Derived Biochar into the Anaerobic Digestion Process through Circular Economic and Environmental Approaches-A Review

The growing energy consumption and the need for a circular economy have driven considerable interest in the anaerobic digestion (AD) of organic waste, offering potential solutions through biogas and digestate production. AD processes not only have the capability to reduce greenhouse gas emissions but also contribute to the production of renewable methane. This comprehensive review aims to consolidate prior research on AD involving different feedstocks. The principles of AD are explored and discussed, including both chemical and biological pathways and the microorganisms involved at each stage. Additionally, key variables influencing system performance, such as temperature, pH, and C/N ratio are also discussed. Various pretreatment strategies applied to enhance biogas generation from organic waste in AD are also reviewed. Furthermore, this review examines the conversion of generated digestate into biochar through pyrolysis and its utilization to improve AD performance. The addition of biochar has demonstrated its efficacy in enhancing metabolic processes, microorganisms (activity and community), and buffering capacity, facilitating Direct Interspecies Electron Transfer (DIET), and boosting CH4 production. Biochar also exhibits the ability to capture undesirable components, including CO2, H2S, NH3, and siloxanes. The integration of digestate-derived biochar into the circular economy framework emerges as a vital role in closing the material flow loop. Additionally, the review discusses the environmental benefits derived from coupling AD with pyrolysis processes, drawing on life cycle assessment investigations. Techno-economic assessment (TEA) studies of the integrated processes are also discussed, with an acknowledgment of the need for further TEA to validate the viability of integrating the biochar industry. Furthermore, this survey examines the techno-economic and environmental impacts of biochar production itself and its potential application in AD for biogas generation, aiming to establish a more cost-effective and sustainable integrated system.

Comprehensive hydrothermal pretreatment of municipal sewage sludge: A systematic approach

This study provides a comprehensive analysis of the potential impact of hydrothermal pretreatment (HTP) on municipal thickened waste-activated sludge (TWAS) and its integration with anaerobic digestion (AD). The research demonstrates that HTP conditions (170 °C, 3 bars for 30 min) can increase the solubilization of macromolecular organic compounds by 41%, which enhances biodegradability in semicontinuous bioreactors. This treatment also results in a 50% reduction in chemical oxygen demand (COD) and a 63% increase in the destruction of volatile solids (VS). The combination of HTP with AD significantly boosts methane yields by 51%, reaching 176 ml/g COD, and improves the digestate dewaterability, doubling the solid content in the dewatered cake. However, a higher polymer dose is required compared to conventional AD. Microbial community analysis correlates the observed performance and alterations; it indicates that HTP enhances resilience to stress conditions such as ammonia toxicity. This comprehensive study provides valuable insights into the transition from wastewater treatment plants (WWTPs) to resource recovery facilities (RRF) in line with circular economy principles.

Integrated Biorefinery for a Next-Generation Methanization Process Focusing on Volatile Fatty Acid Valorization: A Critical Review

This review addresses the critical issue of a rapidly increasing worldwide waste stream and the need for sustainable management. The paper proposes an integrated transformation toward a next-generation methanization process, which leads not only to treating waste but also to converting it into higher value compounds and greener energy. Although the current and commonly used anaerobic digestion process is useful for biogas production, it presents limitations of resource exploitation and some negative environmental impacts. Focusing on the acidogenic stage in waste stream processing, the paper discusses the recent strategies to enhance the recovery of volatile fatty acids (VFAs). These acids serve as precursors for synthesizing a variety of biochemicals and biofuels, offering higher value products than solely energy recovery and soil fertilizers. Additionally, the importance of recycling the fermentation residues back into the biorefinery process is highlighted. This recycling not only generates additional VFAs but also contributes to generating clean energy, thereby enhancing the overall sustainability and efficiency of the waste management system. Moreover, the review discusses the necessity to integrate life cycle assessment (LCA) and techno-economic analysis (TEA) to evaluate the environmental impacts, sustainability, and processing costs of the proposed biorefinery.

Existing evidence on the potential of soils constructed from mineral wastes to support biodiversity: a systematic map

BACKGROUND

The development of cities and transport infrastructure produces a large volume of mineral waste (e.g. excavated earth material). At the same time, cities are increasingly trying to develop green infrastructures, given the ecosystem services they provide to people, but this comes with considerable economic and environmental costs associated with the transfer of fertile soil from rural areas to cities. In a circular economy approach, the reuse of mineral waste to build fertile soil is a substantial opportunity to reduce the economic and environmental costs of both mineral waste management and green infrastructure development. Soils constructed from these materials (constructed Technosols) must be able to support vegetation growth and become a suitable living environment for soil organisms. This requires ecological engineering to maximise the potential of constructed soils for biodiversity, both from a taxonomic and functional perspective. In this context, we systematically mapped the evidence related to the ability of soils constructed from mineral wastes to support biodiversity.

METHODS

We gathered published and grey literature through searches in two publications databases (Scopus and Web of Science Core Collection), one search engine (Google Scholar), nine organisational websites and through a call for literature. Titles, abstracts, and full-texts were successively screened using eligibility criteria. All included studies were described with coded variables and a database was produced. The extent of evidence was assessed and knowledge clusters and gaps were identified.

REVIEW FINDINGS

The searches yielded 9265 articles, and 153 articles were retained after the screening process. More than half of these articles were from European countries, with France leading the field with 40 articles, followed by Spain (15 articles) and Italy (10 articles). Most of the articles (75%) were produced after 2015. The main reasons for constructing soils from mineral waste were for mine rehabilitation (35%), waste recycling (16%) and experimental purpose (15%). The 153 articles were divided into 1962 studies, a study being a combination of a taxon, an intervention (i.e. soil construction) and a measured outcome. Among these studies, the most studied biological group is plants (69% of studies) and especially herbaceous species (32%), followed by microorganisms (17%) and invertebrates (14%). The most used type of mineral waste is mine waste (31% of studies) followed by excavated soil (16%) and demolition waste (14%). Finally, the most frequently measured outcome is plant growth (42% of studies), followed by organism abundance (16%) and diversity (10%).

CONCLUSIONS

Three main knowledge clusters were identified which could be addressed in the future for full synthesis of the results: (1) How well do plants grow in soils constructed from mineral wastes? (2) What is the potential of soils constructed from mineral wastes to support biodiversity? and (3) How do microbial communities develop in soils constructed from mineral wastes? There is a lack of studies investigating several biological groups at the same time: only 6 articles out of 153 investigated the response of both plants, invertebrates and microorganisms to soil construction. More research is therefore needed on the ability to support a diversity of organisms.

Municipal Compost Public Health, Waste Management, and Urban Agriculture: A Decadal Study of Fugitive Pb in City of Boston, Massachusetts, USA

Compostable materials constitute roughly half of waste generated globally, but only 5% of waste is actually processed through composting, suggesting that expanding compost programs may be an effective way to process waste. Compostable waste, if properly collected and processed, has value-added end use options including: residential and park landscaping, remediation of brownfield sites, and as growing media in urban agriculture (UA). Since 2001, our lab has partnered with The Food Project, a non-profit focused on youth leadership development through urban farming. From 2006 to 2022 we collected compost materials that were delivered to the farm from a variety of local sources and analyzed a suite of biogeochemical properties including lead (Pb) concentrations, organic carbon, and grain size distribution. Pb concentrations of Boston's municipal compost always exceeded the current City of San Francisco soil and compost purchase standard (80 μg/g). In 2012 Boston's composting program was halted when it exceeded the 400 μg/g Environmental Protection Agency's Pb in soil benchmark. Urban Pb is geomobile and must be managed to minimize resuspension and transport of fines whose Pb concentration is often elevated compared to bulk compost. Consequently, urban farmers have to source lower Pb compost from suburban suppliers at significantly greater cost. Over a 15 year period and through several city vendor contracts, Pb concentrations in municipal compost remain at levels that warrant continued surveillance and risk assessment.

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).

A critical review on global CO2 emission: where do industries stand?

Global CO2 emissions from different industries have been increasing at an alarming rate. This growth is outpacing the efforts, nations are putting in place to reduce their carbon footprints. In this topical review, we critically analyze the level of CO2 emissions on a global scale and across various industries and activities within them and the dominant anthropogenic forcing instability. The global CO2 emission from various economic sectors such as industries, transportation and variety of waste sources were traced globally and regionally. To contextualize our review, the sector wise CO2 emission trends data for a period more than a decade is reviewed which highlighted the main sources of emissions. The data shows the overall reduction of carbon footprints and its progress across various sectors is very limited. The governing factors for this continued global pattern can be ascribed to two main factors: high consumer demands, and poor efforts towards shifting low and zero carbon services across all sectors. Some efforts have been witnessed to shift towards clean fuels and renewables, particularly in Europe and North America. However, rapid growth in industrialization limits the shifting of fossil-based energy systems towards less harmful systems. In Asia, particularly in eastern, southern, and south-eastern regions, the carbon footprints were found to increased owing to a huge demand for materials production, travelling and energy services. Therefore, it is of utmost importance to identify, understand and tackle the most persistent and climate-harmful factors across all industries and drive such policies to substitute the fossil fuels with renewables.

Learning from the past to plan for the future: An historical review of the evolution of waste and resource management 1970-2020 and reflections on priorities 2020-2030 - The perspective of an involved witness

Improving waste and resource management (WaRM) around the world can halve the weight of plastics entering the oceans, significantly mitigate global heating and contribute directly to 12 of 17 sustainable development goals (SDGs). Achieving such results demands understanding and learning from historical evolution of WaRM. The baseline is 1970, prior to environmental legislation. Early steps in the Global North focused on the 'technical fix' within strictly enforced legal frameworks, first bringing hazardous wastes and municipal solid wastes (MSW) under control, then gradually ramping up environmental standards. Using modern technologies to the Global South often failed due to institutional and financial constraints. From 1990, focus switched to integrating technical and governance aspects: local institutional coherence, financial sustainability, provider inclusivity, user inclusivity, national legislative and policy framework. The Global North rediscovered recycling, using policy measures to promote segregation at source; this relied on new markets in emerging economies, which had largely disappeared by 2020. The Global South is making progress on bringing wastes under control, but around 2.7 billion people lack access to waste collection, while ~40% of collected MSW is open dumped or burned - a continuing global waste emergency. So, much remains to be done to move further towards a circular economy. Three policy priorities are critical for all countries: access to sustainable financing, rethinking sustainable recycling and worldwide extended producer responsibility with teeth. Extending services to unserved communities (SDG11.6.1) requires a people-centred approach, working with communities to provide both quality services and decent livelihoods for collection and recycling workers.

Improving waste management by focussing on goals: A mini review of the publication sector

The rationale for this article is that often, decision-makers in waste management (wm) tend to neglect goals and confuse them with means like circular economy or waste hierarchy. Because clear goals are crucial for developing effective wm strategies, the objectives of this mini review are (1) to clarify wm goals in a historical context by a literature review, (2) to investigate how (a) these goals have been observed in general scientific publishing and (b) specifically in Waste Management and Research (WM&R) and (3) to recommend measures for better consideration of wm goals by the publication sector. Based on general as well as specific bibliographic analyses of databases in Scopus and Google Scholar, the study confirms that little attention was given to wm goals in scientific publishing. For instance, during the first 40 years of WM&R, 63 publications and eight editorials were found containing terms related to wm goals, but only 14 respectively and eight explicitly discuss wm goals. We recommend focussing more on wm goals. Editors, authors, reviewers and professional associations in the field of wm should become aware of this challenge and react. If WM&R decides to become a strong platform for the issue wm goals, it will be in a unique selling proposition and more authors, articles and readers are likely to result. This article aims at setting a starting signal for such an endeavour.

Forecasting the effects of municipal solid plastic waste generation and streaming using system dynamics: A case study in Dubai

To effectively manage municipal solid plastic waste (MSPW), municipalities need to select an appropriate combination of policies and technologies. Numerous policies and technologies are inputs for this selection problem, whereas decision-makers pursue several economic and environmental outcomes. The MSPW flow-controlling variables serve as an intermediary between the inputs and outputs of this selection problem. Examples of the flow-controlling, mediating variables include the source-separated and incinerated MSPW percentages. This study proposes a system dynamics (SD) model that anticipates the influence of these mediating variables on multiple outputs. The outputs include volumes of four MSPW streams and three sustainability-related externalities: GHG emissions reduction, net energy savings, and net profit. Using the SD model, decision-makers can determine the best levels for the mediating variables based on the desired outputs. Consequently, decision-makers can identify the MSPW system stages at which they must choose policies and technologies. Additionally, the values of the mediating variables will help clarify for decision-makers how strict they should be when imposing policies and how much to invest in technologies at the selected MSPW system stages. The SD model is applied to Dubai's MSPW problem. A sensitivity analysis experiment conducted on Dubai's MSPW system demonstrates that the earlier an action is taken, the better the results will be achieved. Consequently, reducing municipal solid waste should take priority, followed by increasing source separation, then post-separation, and finally, incineration with energy recovery. The results of another experiment employing a full factorial design with four mediating variables indicate that recycling would impact GHG emissions and energy reduction values more than incineration with energy recovery. However, these savings are global in nature.

Transdisciplinary pragmatic melioration for the plastic life cycle: Why the social, natural, and technical sciences should prioritize reducing harm

Plastics underpin modern society but also threaten to choke it. Only 9 % of all plastic waste is recycled, usually with loss of quality ("downcycling"); the rest is landfilled or dumped (79 %) or incinerated (12 %). Put bluntly, the "plastic age" needs a "sustainable plastic culture." Consequently, we urgently need to develop a global and transdisciplinary approach not only to fully recycle plastics but also to manage the harms across their life cycle. The past decade has witnessed an explosion in research on new technologies and interventions that purport to help solve the plastic waste challenge; however, this work has, in most cases, been carried forward within single disciplines (for example, researching novel chemical and bio-based technologies for plastic degradation, engineering processing equipment innovations, and mapping recycling behaviours). In particular, although there has been vast progress within individual scientific fields, such work does not address the complexities of various plastic types and waste management systems. Meanwhile, research on the social contexts (and constraints) of plastic use and disposal is rarely in conversation with the sciences to drive innovation. In short, research on plastics typically lacks a transdisciplinary perspective. In this review, we urge the adoption of a transdisciplinary approach that focuses on pragmatic melioration; such an approach combines the natural and technical sciences with the social sciences to focus on the mitigation of harms across the plastic life cycle. To illustrate our case, we review the status of plastic recycling from these three scientific perspectives. Based on this, we advocate 1) foundational studies to identify sources of harm and 2) global/local interventions aimed at those plastics and aspects of the plastic life cycle that cause maximal harm, both in terms of planetary welfare and social justice. We believe this approach to plastic stewardship can be a showcase for tackling other environmental challenges.

U.S. plastic waste exports: A state-by-state analysis pre- and post-China import ban

This study analyzes the regional implications of China's 2017 import ban on plastic waste by examining U.S. census data. A statistically significant decrease in total U.S. plastic waste exports was found, dropping from about 1.4 million tons to 0.6 million tons in the post-ban period. California remained the top exporter, throughout both pre- and post-ban periods, while South Carolina exhibited the highest per capita exports. Malaysia emerged as the largest importer of U.S. plastic waste, followed by Vietnam, Indonesia, and Thailand. The ban also led to a change in the composition of the exported plastic waste. Ethylene polymers increased from 32.6% of total exports in the pre-ban period to 46.9% in the post-ban period. Other plastics (vinyl chloride polymers, styrene polymers, and for plastics not elsewhere specified or included) decreased from 67.4% of total exports in the pre-ban period to 53.1% in the post-ban period. Moreover, we found that exporting plastic waste has significant environmental and human health impacts. For example, the Global Warming Potential (GWP) decreased from 20 million tons CO2-eq in the scenario where 100% of plastics are exported, or 25 million tons exported from the U.S. since 2002, to -11.1 million tons CO2-eq in the scenario where 100% of plastics are treated domestically. Transportation exacerbates these impacts for exported waste scenarios, increasing to 5.4 million tons CO2-eq when plastics are exported by ship while decreasing to 0.9 million tons CO2-eq for domestic treatment. Although exporting plastic waste is initially cost-effective, our study highlights that investing in domestic waste management can yield significant long-term benefits, considering the environmental and public health impacts. Therefore, it is crucial to prioritize context-specific solutions to address the challenges of the evolving global plastic waste landscape.

Large Virtual Transboundary Hazardous Waste Flows: The Case of China

The Basel Convention and prior studies mainly focused on the physical transboundary movements of hazardous waste (transporting waste from one region to another for cheaper disposal). Here, we take China, the world's largest waste producer, as an example and reveal the virtual hazardous waste flows in trade (outsourcing waste by importing waste-intensive products) by developing a multiregional input-output model. Our model characterizes the impact of international trade between China and 140 economies and China's interprovincial trade on hazardous waste generated by 161,599 Chinese enterprises. We find that, in 2015, virtual hazardous waste flows in China's trade reached 26.6 million tons (67% of the national total), of which 31% were generated during the production of goods that were ultimately consumed abroad. Trade-related production is much dirtier than locally consumed production, generating 26% more hazardous waste per unit of GDP. Under the impact of virtual flows, 40% of the waste-intensive production and relevant disposal duty is unequally concentrated in three Chinese provinces (including two least-developed ones, Qinghai and Xinjiang). Our findings imply the importance of expanding the scope of transboundary waste regulations and provide a quantitative basis for introducing consumer responsibilities. This may help relieve waste management burdens in less-developed "waste havens".

Dual-objective modeling and optimization of a low-carbon waste-classified collection problem

With improved quality of life, types of waste have become increasingly complex, and waste classification has become a global issue. As a result, the world is facing a waste-classified collection problem. However, the existing research on waste collection has paid little attention to waste classification. In this paper, we consider the pretreatment and classification of waste transfer stations. In recent years, global warming caused by carbon emissions has become a serious problem. Therefore, this work proposes the first dual-objective multi-depot two-echelon green vehicle routing system with various pickups to optimize waste-classified collection based on a mixed-integer programming model. To ensure the efficiency of our developed model, we designed a multiobjective brainstorming optimization algorithm with a novel clustering strategy based on the rank-clustering method and differential mutation. Compared with two classical multiobjective optimization algorithms in various generated test instances and a real-world case, the experimental results showed that the proposed model can help sanitation departments improve the economic and environmental benefits of waste-classified collection, and the proposed algorithm is an excellent optimizer for solving associated problems.

Understanding challenges associated with plastic and bacterial approach toward plastic degradation

Plastic is widely used in every sector due to its stability, durability, and low cost. The widespread use of plastic results in the compilation of plastic waste in the environment. The buildup of such a vast volume of plastic garbage has emerged as the primary cause of environmental pollution, including air, land, and water pollution. Plastics contain various harmful chemicals and toxic substances that can leak and adversely affect humans and other organisms. Managing this much plastic waste is a very challenging task; therefore, an appropriate technique is needed to address this problem. Various methods are used, such as chemical, physical, and biological, to degrade plastic waste. Bacterial degradation is known to be the most effective technique for the biodegradation approach to overcome this issue. Biodegradation has played a crucial role in removing these polluting wastes more efficiently and eco-friendly. The process of biodegradation involves a variety of bacteria, such as Acinetobacter baumannii, Bacillus weihenstephanensis, Pseudomonas aeruginosa, Pseudomonas fluorescens, Rhodococcus ruber, and so on. Biodegradation of plastic takes place through various biochemical pathways, including biodeterioration, biofragmentation, assimilation, and mineralization. During biodegradation, bacteria produce enzymes like esterase, cutinase, laccase, lipase, and others that break down and transform plastic polymers into microbial biomass and gases. This review aims to explain how bacteria contribute to the breakdown of plastic.

Urban Households' Willingness to Pay to Improve Municipal Solid Waste Collection Services and Associated Factors: A Double-Bounded Contingent Valuation Study in Harar City, Ethiopia

Municipal solid waste collection (MSWC) service financing is a challenge for governments in developing countries, with little or no contribution from the service users. In most Ethiopian cities, residents do not pay for MSWC. This study aims to estimate households' willingness to pay (WTP) for improved municipal solid waste collection service in Harar city. A cross-sectional study was conducted among 331 households employing the contingent valuation method with a double-bounded dichotomous choice format. The hypothetical program works to collect solid waste twice a week, house-to-house, and safely dispose of it to reduce environmental and health impacts. The Tobit regression model was used to account for the determinants of households' WTP. Findings showed that 89% (95% CI: 85.4, 92.5) of households were WTP for the improved waste collection program, with an average yearly amount of US$12. The Tobit model shows that being married (β = 6.9, 95% CI: 1.2, 13.7), having a monthly household income of >8000 ETB (β = 31.9, 95% CI: 22.1, 41.7), attending education about MSWM (β = 11.8, 95% CI: 5.6, 18.1), having temporary storage at household level (β = 15.3, 95% CI: 9.5, 21.2), and recycling practices (β = 5.5, 95% CI: 1.2, 10.8) positively influenced the WTP. Interventions like providing educational programs about waste handling and recycling and providing or encouraging households to have temporary storage at the household level are needed to enhance users' WTP. The policy implication of the finding is that community contribution through service fees could be a strategy for sustainable financing.

Assessment of COVID-19 vaccination-related medical waste management practices in Bangladesh

The COVID-19 pandemic forces people to be vaccinated as early as possible. The COVID-19 vaccination program certainly raised the medical waste volume all over the world, including in Bangladesh. Numerous recent reports showed a fragile medical waste management system in Bangladesh; during the pandemic, the situation became worse. In addition, the nation-wide ongoing COVID-19 vaccination processes have been posing an extra burden to the existing biomedical waste management in the country. Failing to proper management of this waste might be a threat to human and environmental health. Therefore, the study investigated the current COVID-19 vaccine waste management practices in Bangladesh and made a comparison to the proposed standard operating procedures of international organizations and vaccine waste management practices of two other countries (USA and India). The study was carried out through a mixed methodological approach such as qualitative and quantitative, including a questionnaire survey in 15 Upazila of 4 Districts (Dhaka, Narayanganj, Manikganj, and Gazipur) of Bangladesh. The article focused on a nation-wide legitimate COVID-19 vaccination waste estimation, strength, weakness, opportunity, and threat (SWOT) analysis and drivers, pressure, state, impact, and response (DPSIR) framework analysis to identify the present state of medical waste management in the study area. The study found an excellent segregation system (100%) but very poor waste handling (35.5%) along with very poor syringes and sharps disposal method (open burning without buried 46.6%) and poor vials disposal method (without disinfection/open dump 52%) of vaccine waste. It is estimated that about 58 and 257.85 tonnes of syringes (with needles and packaging) and vaccine vials (Sinopharm 2 doses) waste have been generated since the mass-vaccination program started. Upon SWOT analysis, good separation techniques, poor waste management (ex-situ), enough space for management, and environmental and human health concerns were mostly identified as a strength, weakness, opportunity, and threat, respectively. Finally, a DPSIR framework was prepared for vaccine waste generation and its consequences in the studied area. This study will be useful to prepare a suitable vaccination waste management system in Bangladesh.

Omics approaches in bioremediation of environmental contaminants: An integrated approach for environmental safety and sustainability

Non-degradable pollutants have emerged as a result of industrialization, population growth, and lifestyle changes, endangering human health and the environment. Bioremediation is the process of clearing hazardous contaminants with the help of microorganisms, and cost-effective approach. The low-cost and environmentally acceptable approach to removing environmental pollutants from ecosystems is microbial bioremediation. However, to execute these different bioremediation approaches successfully, this is imperative to have a complete understanding of the variables impacting the development, metabolism, dynamics, and native microbial communities' activity in polluted areas. The emergence of new technologies like next-generation sequencing, protein and metabolic profiling, and advanced bioinformatic tools have provided critical insights into microbial communities and underlying mechanisms in environmental contaminant bioremediation. These omics approaches are meta-genomics, meta-transcriptomics, meta-proteomics, and metabolomics. Moreover, the advancements in these technologies have greatly aided in determining the effectiveness and implementing microbiological bioremediation approaches. At Environmental Protection Agency (EPA)-The government placed special emphasis on exploring how molecular and "omic" technologies may be used to determine the nature, behavior, and functions of the intrinsic microbial communities present at pollution containment systems. Several omics techniques are unquestionably more informative and valuable in elucidating the mechanism of the process and identifying the essential player's involved enzymes and their regulatory elements. This review provides an overview and description of the omics platforms that have been described in recent reports on omics approaches in bioremediation and that demonstrate the effectiveness of integrated omics approaches and their novel future use.

Waste Management in Qatar: A Systematic Literature Review and Recommendations for System Strengthening

Billions of tons of waste are generated annually, with the amount of waste rapidly increasing and its management expected to worsen. Qatar is a small and wealthy country in the Arabian Peninsula that is undergoing enormous economic and urban development. This study presents the results of a systematic literature review on waste management in Qatar and offers recommendations for system strengthening based on an analysis of the available evidence. The PRISMA guidelines were followed to review literature from the ProQuest and SCOPUS platforms, from which 82 unique publications were analyzed according to ten themes. The results draw upon diverse disciplinary and research focus areas related to waste management, ranging from the generation of value-added products from wastes to the role of religion in waste management awareness. The main recommendations emerging from the available evidence include the need for a holistic approach to address increasing waste generation, which must include diverse stakeholders such as government entities, researchers, and broad community representation for decision making as well as raising awareness for behavior change. Additionally, the main waste types, including construction, food, plastic, and electronic wastes, require specific attention since the cause of generation and type of management varies accordingly. The rise of interest in improving waste management, in particular to work toward meeting the targets of the Qatar National Vision and the National Development Strategy should bring about positive outcomes for strengthening waste management systems.

Delineating the Drivers and Functionality of Methanogenic Niches within an Arid Landfill

Microbial communities mediate the transformation of organic matter within landfills into methane (CH₄). Yet their ecological role in CH₄ production is rarely evaluated. To characterize the microbiome associated with this biotransformation, the overall community and methanogenic Archaea were surveyed in an arid landfill using leachate collected from distinctly aged landfill cells (i.e., younger, intermediate, and older). We hypothesized that distinct methanogenic niches exist within an arid landfill, driven by geochemical gradients that developed under extended and age-dependent waste biodegradation stages. Using 16S rRNA and mcrA gene amplicon sequencing, we identified putative methanogenic niches as follows. The order Methanomicrobiales was the most abundant order in leachate from younger cells, where leachate temperature and propionate concentrations were measured at 41.8°C ± 1.7°C and 57.1 ± 10.7 mg L⁻¹. In intermediate-aged cells, the family Methanocellaceae was identified as a putative specialist family under intermediate-temperature and -total dissolved solid (TDS) conditions, wherein samples had a higher alpha diversity index and near CH₄ concentrations. In older-aged cells, accumulating metals and TDS supported Methanocorpusculaceae, “Candidatus Bathyarchaeota,” and “Candidatus Verstraetearchaeota” operational taxonomic units (OTUs). Consistent with the mcrA data, we assayed methanogenic activity across the age gradient through stable isotopic measurements of δ¹³C of CH₄ and δ¹³C of CO₂. The majority (80%) of the samples’ carbon fractionation was consistent with hydrogenotrophic methanogenesis. Together, we report age-dependent geochemical gradients detected through leachate in an arid landfill seemingly influencing CH₄ production, niche partitioning, and methanogenic activity.

IMPORTANCE Microbiome analysis is becoming common in select municipal and service ecosystems, including wastewater treatment and anaerobic digestion, but its potential as a microbial-status-informative tool to promote or mitigate CH₄ production has not yet been evaluated in landfills. Methanogenesis mediated by Archaea is highly active in solid-waste microbiomes but is commonly neglected in studies employing next-generation sequencing techniques. Identifying methanogenic niches within a landfill offers detail into operations that positively or negatively impact the commercial production of methane known as biomethanation. We provide evidence that the geochemistry of leachate and its microbiome can be a variable accounting for ecosystem-level (coarse) variation of CH₄ production, where we demonstrate through independent assessments of leachate and gas collection that the functional variability of an arid landfill is linked to the composition of methanogenic Archaea.

The impact of marine debris on cetaceans with consideration of plastics generated by the COVID-19 pandemic

The accumulation of human-derived debris in the oceans is a global concern and a serious threat to marine wildlife. There is a volume of evidence that points to deleterious effects of marine debris (MD) on cetaceans in terms of both entanglement and ingestion. This review suggests that about 68% of cetacean species are affected by interacting with MD with an increase in the number of species reported to have interacted with it over the past decades. Despite the growing body of evidence, there is an ongoing debate on the actual effects of plastics on cetaceans and, in particular, with reference to the ingestion of microplastics and their potential toxicological and pathogenic effects. Current knowledge suggests that the observed differences in the rate and nature of interactions with plastics are the result of substantial differences in species-specific diving and feeding strategies. Existing projections on the production, use and disposal of plastics suggest a further increase of marine plastic pollution. In this context, the contribution of the ongoing COVID-19 pandemic to marine plastic pollution appears to be substantial, with potentially serious consequences for marine life including cetaceans. Additionally, the COVID-19 pandemic offers an opportunity to investigate the direct links between industry, human behaviours and the effects of MD on cetaceans. This could help inform management, prevention efforts, describe knowledge gaps and guide advancements in research efforts. This review highlights the lack of assessments of population-level effects related to MD and suggests that these could be rather immediate for small populations already under pressure from other anthropogenic activities. Finally, we suggest that MD is not only a pollution, economic and social issue, but also a welfare concern for the species and populations involved.

China's roadmap to plastic waste management and associated economic costs

Plastic is one commonly used polymer material to support our daily lives. However, once the plastic waste enters the environment, it slowly degrades, which causes long-term and deep ecological environmental problems. As the world's largest plastic producer and consumer, China generated around 26.74 million tons of plastic waste in 2019, and has made ambitious policies to cope with the plastic waste issues. This study predicts the generation trends and management costs of plastic waste in China from 2020 to 2035 under three different scenarios (Business as usual-BAU, Current policy scenario -CPS, and Target policy scenario-TPS), in which China is divided into three regions for specific policy implications. In addition, the scenario analysis and Monte Carlo simulations are used to obtain confidence interval of assessments. The results show that the plastic waste emission will be 34.82 million tons under BAU, 13.49 million tons under CPS and 2.63 million tons under TPS in 2035, respectively, and there will be significant changes in regional contributions in plastic waste emission (e.g., Eastern region: 45.7% to 9.7%; Central region:25.2% to 30.9%; Western region: 29.1% to 59.4% from 2019 to 2035 under TPS). In addition, the environmental and economic benefits increase with the rigor of plastic waste management policy as there will generate a net income of US$3.01 billion under TPS compared to the cost of US$ 2.61 billion under BAU and US$120 million under CPS. In view of this, it is vital that China develop appropriate plastic management policies based on the status of various regions, attempt to achieve economic development while reducing plastic waste emissions, and finally achieving a "win-win" situation of economy and environment.

Belt and Road Environmental Implications for South Asia

The Belt and Road Initiative (BRI) can play a significant role in the sustainable development of South Asia if appropriately implemented. Apart from the economic, trade, and cultural benefits of this colossal infrastructure, less is known about its environmental impact on South Asia. This study looks closely at the potential impact of the BRI on the South Asian environment. This research is based on the government-issued environmental policies, peer-reviewed literature, media articles, and reports. It has been suggested that the BRI could have a negative impact on the South Asian environment, which provided if does not consider the Paris agreement with its partners in the region. The study suggests that partner countries should adopt the BRI project to the principles of environmental impact assessment.

Livestock Wastes Sustainable Use and Management: Assessment of Raw Sheep Wool Reuse and Valorization

Worldwide, around 998 million tons of agricultural waste are generated yearly, including livestock wastes, which create several critical environmental issues if not properly treated. In this study, a Geographical Information System (GIS)-based model to locate and quantify both the yearly amount of livestock waste, i.e., sheep wool, and the territorial distribution of sheep farms, was carried out and applied within the selected study area. The aim was to identify those territorial areas most suitable for localizing new shared wool collection centers to sustainably manage the reuse of this waste as potential green building material. Data related to both sheep farms and sheep number and the related sheep shared wool (SSW) yearly production were acquired and applied in GIS. By GIS-based model results, two collection centers have been identified within the provinces of Agrigento and Enna. Then, to develop a sustainable reuse in terms of reducing environmental impact due to the SSW logistics and supply phase, a possible third collection center was localized within the territorial area belonging to the province of Ragusa (south area of the Sicily). In this research, for the first time the issue above reported was addressed, by achieving results that contribute at developing an efficient collection chain for recovering and properly reusing SSW to respond adequately to a further industrial scale production.

Mechanical and microstructural performance of concrete containing high-volume of bagasse ash and silica fume

In this study, researchers examined the effect of replacing a high-volume of cement with sugarcane bagasse ash (BA) and silica fume (SF). In addition to the control, three binary and three ternary blends of concrete containing different percentages of cement/BA and cement/BA/SF were tested to determine the various mechanical and microstructural properties of concrete. For each mix, eighteen cylindrical concrete specimens were cast followed by standard curing (moist at 20 °C) to test the compressive and tensile strengths of three identical specimens at 7, 28, and 91 days. The test results indicated that the binary mix with 20% BA and ternary mix with 33% BA and 7% SF exhibited higher strengths than all the other mixes, including the control. The higher strengths of these mixes are also validated by their lower water absorption and apparent porosity than the other mixes. Following mechanical testing, the micro and pore structures of all mixes were investigated by performing scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM–EDS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and nitrogen (N₂) adsorption isotherm analysis. In SEM–EDS analysis, a dense and compact microstructure was observed for the BA20 and BA33SF7 mixtures due to the formation of high-density C–S–H and C–H phases. The formation of a large amount of C–S–H phases was observed through FTIR, where a prominent shift in peaks from 955 to 970 cm⁻¹ was observed in the spectra of these mixes. Moreover, in N₂ adsorption isotherm analysis, a decrease in the intruded pore volume and an increase in the BET surface area of the paste matrix indicate the densification of the pore structure of these mixes. As observed through TGA, a reduction in the amount of the portlandite phase in these mixes leads to the formation of their more densified micro and pore structures. The current findings indicate that BA (20%) and its blend with SF (40%) represents a potential revenue stream for the development of sustainable and high-performance concretes in the future.

The world-wide waste web

Countries globally trade with tons of waste materials every year, some of which are highly hazardous. This trade admits a network representation of the world-wide waste web, with countries as vertices and flows as directed weighted edges. Here we investigate the main properties of this network by tracking 108 categories of wastes interchanged in the period 2001–2019. Although, most of the hazardous waste was traded between developed nations, a disproportionate asymmetry existed in the flow from developed to developing countries. Using a dynamical model, we simulate how waste stress propagates through the network and affects the countries. We identify 28 countries with low Environmental Performance Index that are at high risk of waste congestion. Therefore, they are at threat of improper handling and disposal of hazardous waste. We find evidence of pollution by heavy metals, by volatile organic compounds and/or by persistent organic pollutants, which are used as chemical fingerprints, due to the improper handling of waste in several of these countries.

The 2001–2019 web of international waste trade is investigated, allowing the identification of countries at threat of improper handling and disposal of waste. Chemical tracers are used to identify the environmental impact of waste in these countries.

Conceptualization of Bioreactor Landfill Approach for Sustainable Waste Management in Karachi, Pakistan

Finding a sustainable approach for municipal solid waste (MSW) management is becoming paramount. However, as with many urban areas in developing countries, the approach applied to MSW management in Karachi is neither environmentally sustainable nor suitable for public health. Due to adoption of an inefficient waste management system, society is paying intangible costs such as damage to public health and environment quality. In order to minimize the environmental impacts and health issues associated with waste management practices, a sustainable waste management and disposal strategy is required. The aim of this paper is to present a concept for the development of new bioreactor landfills for sustainable waste management in Karachi. Furthermore, this paper contributes to estimation of methane (CH4) emissions from waste disposal sites by employing the First Order Decay (FOD) Tier 2 model of the Intergovernmental Panel on Climate Change (IPCC) and determining of the biodegradation rate constant (k) value. The design and operational concept of bioreactor landfills is formulated for the study area, including estimation of land requirement, methane production, power generation, and liquid required for recirculation, along with a preliminary sketch of the proposed bioreactor landfill. This study will be helpful for stockholders, policy makers, and researchers in planning, development, and further research for establishment of bioreactor landfill facilities, particularly in the study area as well as more generally in regions with a similar climate and MSW composition.

Current Status and Review of Waste-to-Biogas Conversion for Selected European Countries and Worldwide

Growing world population and increasing population density are leading to increasing waste production with biological waste amounting to several billion tonnes annually. Together with the increasing need for renewable energy sources, waste-to-biogas conversion as a prime example of waste-to-energy technology represents a facile way of solving two problems simultaneously. This review aims to address the recent progress in the field of waste-to-biogas technology, which is lately facing intensive research and development, and present the current status of this waste treatment method both in technological and legislative terms. The first part provides an overview of waste and waste management issues. This is followed by a detailed description of applicable waste-to-energy (WtE) technologies and their current implementation in selected European countries. Moreover, national energy and climate plans (NECPs) of selected EU Member States are reviewed and compared with a focus on implementation of WtE technologies. In a further section, biogas production from waste around the world is reviewed and compared country wise. Finally, an outlook into the future of WtE technologies is provided alongside the conclusions based upon the reviewed data.

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and enhances microbial activity. Co-composted biochar improves soil properties and enhances crop productivity. Pristine and engineered biochar can also be employed for water and soil remediation to remove pollutants. In construction, biochar can be added to cement or asphalt, thus conferring structural and functional advantages. Incorporating biochar in biocomposites improves insulation, electromagnetic radiation protection and moisture control. Finally, synthesising biochar-based materials for energy storage applications requires additional functionalisation.

The wicked problem of waste management: An attention-based analysis of stakeholder behaviours

Surging amounts of waste are reported globally and especially in lower-income countries, with negative consequences for health and the environment. Increasing concern has been raised for the limited progress achieved in practice by diverse sets of policies and programmes. Waste management is a wicked problem characterised by multilayered interdependencies, complex social dynamics and webs of stakeholders. Interactions among these generate unpredictable outcomes that can be missed by decision makers through their understanding and framing of their context. This article aims to identify possible sources of persistent problems by focussing on what captures, shapes and limits the attention of stakeholders and decision-makers, drawing on the attention-based view from organisation theory. The theory describes the process through which issues and opportunities are noticed and how these are translated into actions, by focussing on the influencers at the individual, organisational and context scale. Views on issues and opportunities for waste management were collected in a series of fieldwork activities from 60 participants representing seven main types of stakeholders in the typical lower-middle income Kenyan city of Kisumu. Through a thematic analysis guided by the attention-based view, we identified patterns and misalignment of views, especially between government, community-based organisations and residents, which may contribute to persistent waste problems in Kisumu. Some point to detrimental waste handling practices, from separation to collection and treatment, as the main cause of issues. For others, these practices are due to a poor control of such practices and enforcement of the law. This study's major theoretical contribution is extending the application of attention theory to multi-stakeholder problems and to non-formalized organisations, namely residents and to the new field of waste management. This novel lens contributes a greater understanding of waste issues and their management in Africa that is relevant to policy and future research. By revealing the "wickedness" of the waste problem, we point to the need for a holistic and systems-based policy approach to limit further unintended consequences.

Evidence of Microplastic Translocation in Wild-Caught Fish and Implications for Microplastic Accumulation Dynamics in Food Webs

The presence of microplastics within the gut of animals is well documented. Whether microplastics bioaccumulate in organisms and biomagnify in food webs remains unclear and relies on the ability of microplastics to translocate to other tissues. Here, we demonstrate the widespread presence of microplastics and other anthropogenic microparticles in the gastrointestinal tract, fillet, and livers of seven species of sportfish from Lake Simcoe, Ontario, Canada. Larger fish had a higher microplastic load compared to smaller fish, but the opposite trend was observed with translocated microplastics standardized by fish mass (i.e., smaller fish contained more translocated particles per gram wet weight than larger fish). Moreover, we observed no evidence of biomagnification as there was no significant relationship between the trophic level and total or translocated microplastics per individual. Overall, this suggests that microplastics are translocating, but that excretion of translocated particles or growth dilution may be occurring rather than bioaccumulation and biomagnification. Moreover, the assemblages of shapes and material types varied among tissues, suggesting that particle characteristics may predict biological fate. Our findings highlight the need for further work to understand the mechanisms of microplastic translocation and excretion and the implications for the dynamics of microplastics accumulation in food webs and human exposure.

Design and Operation of Effective Landfills with Minimal Effects on the Environment and Human Health

Totaling at 7.4 billion people, the world's population is rapidly growing, bringing along with it an increase in waste generation. The impact of this exponential increase in waste generation has resulted in the increased formation and utilization of landfills. In the present day, landfills are utilized to dispose of chemical, hazardous, municipal, and electronic wastes. However, despite their convenience, most landfills are improperly managed and face constant changes from the surrounding environment that interfere with their internal landfill processes. The objectives of this mixed review are to highlight the negative impacts landfills have on the environment and public health as well as outline the need for proper management practices to mitigate these effects. Inadequate management of landfills leads to issues concerning leachate collection and landfill gas (LFG) generation, which give rise to groundwater contamination and air pollution. This paper recognizes the disadvantages of utilizing landfills as the main disposal method by focusing on these two primary effects that improper management of landfills has on the environment and human health. Many experts have also reported that communities within close proximity to improperly managed landfills have an increased risk of health issues. Apart from implementing proper landfill management practices, it is important to develop solutions to reduce waste generation altogether. This review discusses some of the innovative methods implemented by other countries to reduce landfill waste and the production of greenhouse gases as well as possible steps individuals can take to minimize their ecological footprints.

Increase in SARS-CoV-2 infected biomedical waste among low middle-income countries: environmental sustainability and impact with health implications

Studies have shown that severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) is a highly infectious disease, with global deaths rising to about 360,438 as of 28 May 2020. Different countries have used various approaches such as lockdown, social distancing, maintenance of personal hygiene, and increased establishment of testing and isolation centers to manage the pandemic. Poor biomedical waste (BMW) management, treatment, and disposal techniques, especially SARS-CoV-2 infected BMW, may threaten the environmental and public health in most developing countries and, by extension, impact the economic status of individuals and the nation at large. This may increase the potential for the transmission of air/blood body fluid-borne pathogens, increase the growth of microorganisms, risk of mutagenesis, and upsurge of more virulent strain. In contrast, uncontrolled substandard burning could increase the potential spread of nosocomial infection and environmental exposure to toxic organic compounds, heavy metals, radioactive, and genotoxic bio-aerosols which might be present in the gaseous, liquid, and solid by-products. The paucity of understanding of pathophysiology and management of the SARS-CoV-2 pandemic has also necessitated the need to put in place appropriate disposal techniques to cater for the sudden increase in the global demand for personal protective equipment (PPE) and pharmaceutical drugs to manage the pandemic and to reduce the risk of preventable infection by the waste. Therefore, there is a need for adequate sensitization, awareness, and environmental monitoring of the impacts of improper handling of SARS-CoV-2 infected BMWs. Hence, this review aimed to address the issues relating to the improper management of increased SARS-CoV-2 infected BMW in low middle-income countries (LMICs).

A Novel Multi-Criteria Sorting Model Based on AHP-Entropy Grey Clustering for Dealing with Uncertain Incoming Core Quality in Remanufacturing Systems

Remanufacturing is a key pillar of a circular economy and helps in recovering used products by extending their life cycle via remanufacturing them into new products. A vital aspect in a remanufacturing system is the quality assessment of incoming worn-out products (cores) prior to remanufacturing to ensure that non-conforming cores are discarded at an early stage in order to avoid unnecessary processing. Therefore, quality sorting plays an important role in core acquisition for remanufacturing systems when attempting to mitigate uncertain incoming core quality as an immediate solution. The main problem is that it is difficult to acquire the important information required to decide on the sorting of incoming cores, such as the core quality. The data are also commonly limited, not always available, or inaccurate. Grey systems are powerful methods in decision making when handling uncertainty with small data. In this paper, we consider the usefulness of grey systems for handling uncertain quality information for sorting incoming cores in a remanufacturing system. For this reason, we propose a multi-criteria quality sorting model based on an analytical hierarchy process (AHP)-entropy model that is coupled with grey clustering using possibility functions. The quality criteria for sorting the incoming cores are considered according to the technological, physical, and usage conditions. To demonstrate the practical contribution of this research, a case study of the quality sorting problem with a heavy-duty equipment remanufacturer is presented. The proposed model consistently classifies the quality of used hydraulic cylinders into two grey classes.

Towards environmental sustainability in the local community: Future insights for managing the hazardous pollutants at construction sites

Although various technologies are being developed in the construction industry, management technologies for achieving environmental sustainability in the local community are still lacking. As such, this study suggests future insights for the development of an automated intelligent environment management system for the promotion of environmental sustainability in the local community, through a systematic review of 1,707 relevant literature. The systematic review was conducted in two steps: (i) quantitative review: keyword co-occurrence and trend analysis; and (ii) qualitative review: a review on monitoring, evaluation, and improvement technologies. As a result, the research level related to the local-level pollutants (noise, vibration, and dust) was found to be quantitatively insufficient, and the limitations of the existing technologies for these pollutants were presented. Eventually, to overcome these limitations, new technologies and application strategies that can be applied to construction sites as future research roadmap to effectively manage the hazardous pollutants were proposed. Furthermore, an intelligent management system should be developed, and the management of environmental complaints is also necessary for environmental sustainability at the local level in the construction industry. As a fundamental study, this study could become a benchmark for future researches dealing with environmental sustainability and hazardous pollutants in the construction industry.

Application of Systems-Approach in Modelling Complex City-Scale Transdisciplinary Knowledge Co-Production Process and Learning Patterns for Climate Resilience

Literature shows that much research has been conducted on the co-production of climate knowledge, but it has neither established a standardized and replicable model for the co-production process nor the emergent learning patterns as collaborators transition from the disciplinary comfort-zone (disciplinary and practice biases) to the transdisciplinary third-space. This study combines algorithmic simulation modelling and case study lessons from Learning Labs under a 4-year (2016–2019) climate change management project called Future Resilience of African CiTies and Lands in the City of Blantyre in Malawi. The study fills the research gap outlined above by applying a systems-approach to replicate the research process, and a Markov process to simulate the learning patterns. Results of the study make a number of contributions to knowledge. First, there are four distinct evolutionally stages when transitioning from the disciplinary comfort-zone to the transdisciplinary third-space, namely: Shock and resistance to change; experimenting and exploring; acceptance; and integration into the third-space. These stages are marked by state probabilities of the subsequent stages relative to the initial (disciplinary comfort-zone) state. A complete transition to the third-space is marked by probabilities greater than one, which is a system amplification, and it signifies that there has been a significant increase in learning among collaborating partners during the learning process. Second, a four-step decision support tool has been developed to rank the plausibility of decisions, which is very hard to achieve in practice. The tool characterizes decision determinants (policy actors, evidence and knowledge, and context), expands the determinants, checks what supports the decision, and then rates decisions on an ordinal scale of ten in terms of how knowledge producers and users support them. Third, for a successful transdisciplinary knowledge co-production, researchers should elucidate three system-archetypes (leverage points), namely: Salient features for successful co-production, determinant of support from collaborators, and knowledge co-production challenges. It is envisioned that academics, researchers, and policy makers will find the results useful in modelling and replicating the co-production process in a methodical and systemic way while solving complex climate resilience development problems in dynamic, socio-technical systems, as well as in sustainably mainstreaming the knowledge co-produced in policies and plans.

Raising Awareness on Solid Waste Management through Formal Education for Sustainability: A Developing Countries Evidence Review

Solid Waste Management (SWM) is a multifaceted problem comprising political, socioeconomic, institutional, and environmental aspects. Due to exponential urban growth, it has become one of the most significant issues faced by urban spaces in developing countries. The gap in environmental knowledge among the youth and the old within developing countries contribute to ecological issues or waste management problems, resulting in unsustainable development, with important consequences in low-income countries. For that matter, a systematic review was conducted aiming to identify and analyse environmental knowledge, awareness, attitudes, and practice studies on SWM from 2010 to 2019 in developing countries. The evidence suggests that students at both secondary and tertiary levels have positive environmental attitudes, and high awareness of environmental issues, but there is a lack of practical education of teachers to guide students to put SWM into practice. Student’s low environmental knowledge is related to a deficiency in teachers’ practical experience in SWM for environmental sustainability. A relationship between teachers’ and students’ knowledge and attitudes towards SWM, as well as differences in awareness, attitude, and practices of SWM linked with education and age, were also found. This review also revealed that the lack of environmental education in most developing countries is caused by fragilities in practical environmental curricula of teachers to respond to modern-day environmental issues for sustainable development and cleaner production (CP). To bridge the knowledge gap between the youth and older people in SWM, environmental sustainability education should be integrated into schools at all levels within developing countries.

100th Anniversary of Macromolecular Science Viewpoint: Redefining Sustainable Polymers

Although Staudinger realized makromoleküles had enormous potential, he likely did not anticipate the consequences of their universal adoption. With 6.3 billion metric tons of plastic waste now contaminating our land, water, and air, we are facing an environmental and public health crisis. Synthetic polymer chemists can help create a more sustainable future, but are we on the right path to do so? Herein, a comprehensive literature survey reveals that there has been an increased focus on "sustainable polymers" in recent years, but most papers focus on biomass-derived feedstocks. In contrast, there is less focus on polymer end-of-life fates. Moving forward, we suggest an increased emphasis on chemical recycling, which sees value in plastic waste and promotes a closed-loop plastic economy. To help keep us on the path to sustainability, the synthetic polymer community should routinely seek the systems perspective offered by life cycle assessment.

Partnerships for sustainable cities as options for improving solid waste management in Nairobi city

Partnerships as enshrined in policies are vital for achieving sustainable cities under the Sustainable Development Goals (SDGs). Indeed the SDGs recognize the importance of partnerships in solid waste management (SWM) as a way of developing workable and reliable waste management systems. SWM in Nairobi city continues to be a great challenge, and poor practices threaten environmental and public health. Ineffective waste management in Nairobi city has been linked to inefficient policy implementation and enforcement by different stakeholders. To effectively address the challenge of sustainable waste management in Nairobi city, amalgamation of strategies amongst several segments, including stakeholders, private and public sectors (formal and informal), non-governmental organizations and communities, is important, through partnerships to implement improved policies, in terms of capacity, financial prudence, and technical and institutional factors. The paper seeks to analyse existing policy framework on SWM and its effectiveness in addressing SWM in Nairobi city. The study is based on a descriptive research design which involved interrogating the stakeholders included in the implementation of the policy frameworks in place. Data were acquired through semi-structured questionnaires administered to 385 respondents and interviews with 10 key informants. The theoretical framework is based on institutional theory and capacity building theories that expound the gaps in policy implementation and the role of partnerships. Policies in SWM should be interlinked for sustainable cities.

Recycling of European plastic is a pathway for plastic debris in the ocean

Polyethylene (PE) is one of the most common types of plastic. Whilst an increasing share of post-consumer plastic waste from Europe is collected for recycling, 46% of separated PE waste is exported outside of the source country (including intra-EU trade). The fate of this exported European plastic is not well known. This study integrated data on PE waste flows in 2017 from UN Comtrade, an open repository providing detailed international trade data, with best available information on waste management in destination countries, to model the fate of PE exported for recycling from Europe (EU-28, Norway and Switzerland) into: recycled high-density PE (HDPE) and low-density PE (LDPE) resins, "landfill", incineration and ocean debris. Data uncertainty was reflected in three scenarios representing high, low and average recovery efficiency factors in material recovery facilities and reprocessing facilities, and different ocean debris fate factors. The fates of exported PE were then linked back to the individual European countries of export. Our study estimated that 83,187 Mg (tonnes) (range: 32,115-180,558 Mg), or 3% (1-7%) of exported European PE in 2017 ended up in the ocean, indicating an important and hitherto undocumented pathway of plastic debris entering the oceans. The countries with the greatest percentage of exported PE ending up as recycled HDPE or LDPE were Luxembourg and Switzerland (90% recycled for all scenarios), whilst the country with the lowest share of exported PE being recycled was the United Kingdom (59-80%, average 69% recycled). The results showed strong, significant positive relationships between the percentage of PE exported out of Europe and the percentage of exports which potentially end up as ocean debris. Export countries may not be the ultimate countries of origin owing to complex intra-EU trade in PE waste. Although somewhat uncertain, these mass flows provide pertinent new evidence on the efficacy and risks of current plastic waste management practices pertinent to emerging regulations around trade in plastic waste, and to the development of a more circular economy.

Evaluating scenarios toward zero plastic pollution

Plastic pollution is a pervasive and growing problem. To estimate the effectiveness of interventions to reduce plastic pollution, we modeled stocks and flows of municipal solid waste and four sources of microplastics through the global plastic system for five scenarios between 2016 and 2040. Implementing all feasible interventions reduced plastic pollution by 40% from 2016 rates and 78% relative to “business as usual” in 2040. Even with immediate and concerted action, 710 million metric tons of plastic waste cumulatively entered aquatic and terrestrial ecosystems. To avoid a massive build-up of plastic in the environment, coordinated global action is urgently needed to reduce plastic consumption; increase rates of reuse, waste collection, and recycling; expand safe disposal systems; and accelerate innovation in the plastic value chain.

Municipal solid waste generation, composition, and management: the global scenario

Purpose

Due to the increasing population and prosperity, the generation rate of municipal solid waste (MSW) has increased significantly, resulting in serious problems on public health and the environment. Every single person in the world is affected by the municipal solid waste management (MSWM) issue. MSWM is reaching a critical level in almost all areas of the world and seeking the development of MSW strategies for a sustainable environment. This paper aims to present the existing global status of MSW generation, composition, management and related problems.

Design/methodology/approach

A total of 59 developed and developing countries have been grouped based on their gross national income to compare the status of various MSWM technologies among them. A total of 19 selection criteria have been discussed to select appropriate MSWM technology(s) for a city/town, which affects their applicability, operational suitability and performance. All risks and challenges arising during the life cycle of the waste to energy (WtE) project have also been discussed. This paper also gives a comparative overview of different globally accepted MSWM technologies and the present market growth of all WtE technologies.

Findings

It was found that most developed countries have effectively implemented the solid waste management (SWM) hierarchy and are now focusing heavily on reducing, reusing and recycling of MSW. On the other hand, SWM has become very serious in low-income and low-middle-income countries because most of the MSW openly dumps and most countries are dependent on inadequate waste infrastructure and the informal sector. There are also some other major challenges related to effective waste policies, availability of funds, appropriate technology selection and adequacy of trained people. This study clears the picture of MSW generation, composition, management strategies and policies at the worldwide context. This manuscript could be valuable for all nations around the world where effective MSWM has not yet been implemented.

Originality/value

This study clears the picture of solid waste generation, composition, management strategies and policies at the worldwide context. This manuscript could be valuable for all nations around the world where effective MSWM has not yet been implemented. In this study, no data was generated. All supporting data were obtained from previously published papers in journals, the outcomes of the international conferences and published reports by government organizations.

Assessment of Used Baby Diapers Composting in Bolivia

Solid waste open dumping in developing countries is a global concern. To move towards sustainable development, mixed waste should be reduced, and recyclable waste recovered. The aim of the current research was to find appropriate solutions to disposable used baby-diapers recycling in Bolivia since it is a waste fraction widely produced and commonly disposed of in open dumps. Composting of the organic diaper hydrogel was assessed in five trials, adding components available locally: cow dung, activated bacteria, and Californian red earthworms (Eisenia fetida). It was observed that about 60 days were globally required for biomass decomposition with cow dung, activated bacteria, and earthworms, and more than 70 days for the treatment of the substrate mixed only with manure, while the diaper hydrogel did not degrade without cow dung. This research is the first that attempted to treat disposable used baby diapers with the vermicomposting process. In general, the outcomes of the research are promising: vermicomposting with cow manure can be a recycling option for disposable used baby diapers, introducing appropriate practices toward a circular economy in developing regions.

Decentralization of solid waste management services in rural Lebanon: Barriers and opportunities

Rapid urbanization, closure of dumps, and insufficient infrastructure funding in Lebanon have resulted in improper municipal solid waste management (MSWM), creating a continuing trash crisis in recent years. In Beirut and Mount Lebanon, MSWM was carried out in centralized waste processing and disposal facilities operated by the government. The trash crisis and failure of the centralized system prompted several municipal authorities to decentralize MSWM by establishing local facilities, paid by the council taxes charged to beneficiary households. To study the feasibility of decentralized MSWM, a survey of 228 households in a rural village in Lebanon explored households' willingness to pay (WTP) for a local MSWM service. For data analysis, a multivariate Tobit model was used to examine the determinants of the WTP amount. Results showed that 79% of surveyed households in the studied village were willing to support local MSWM improvements by contributing an average yearly fee of US$48, representing a 30% increase in their current council taxes. Analysis showed a significant positive association between the WTP amount and the household monthly income level, the residents perceived needs for urgency to act on solid waste management, and the households' responsibility to be involved in MSWM. An interview with the municipality mayor later revealed that financial, technical, and land resources are lacking to enable consideration of a decentralized project for MSWM in the village. Municipalities in rural areas have limited resources and are unable to sustain a decentralized MSWM service unless adjacent towns join effort in supporting and financing MSWM initiatives.

Waste management drivers towards a circular economy in the global south - The Colombian case

Circular Economy (CE) turned into one of the most popular topics worldwide for presenting itself as the solution to problems linked to the traditional "take-make-consume-dispose" system. But, how can CE be addressed as public policies worldwide? While there are ambitious and committed strategies in the European Union and Asia, the path that emerging economies are taking is poorly researched. Therefore, we selected Colombia, a Latin American country which is beginning to implement new public policies that are on par with global concerns. Furthermore, its waste management panorama has been transformed in recent decades due to its legal framework restructuring, differently than others in the region. This article aimed to elucidate which drivers have influenced the waste management policies in Colombia based on its historical context and how these drivers impacted Municipal Waste Management (MWM) systems. Amongst the principal drivers identified, we highlight "financial sustainability" and "inclusive recycling", which have allowed improvements towards a more sustainable waste management in the country. Moreover, it was possible to understand how the current legal framework was structured and its future challenges. This study constitutes a knowledge base for scholars and policymakers from other emerging economies, creating a potential to verify the relationship and antagonisms between waste management drivers and how they affect public policy implementation.

Selective collection of recyclable waste in Universities of low-middle income countries: Lessons learned in Bolivia

The implementation of solid waste selective collection (SC) systems is quite difficult in low-middle income countries. Lack of awareness, infrastructure, administrative support and knowledge about recycling are the main barriers for its operation, reducing the possibility of successes. This paper introduces the methodological approach for assessing a recyclable waste SC project in a Bolivian public University. The waste fractions generated before (2016) and after (2019) the action were assessed, as well as the opinion and knowledge of the students, providing reliable indicators of the improvements and benefits obtained. Results of the waste characterization analysis reported that, after one month of implementation of the system, about 15 kg of plastic and 37.1 kg of paper and cardboard were collected, about 8 wt% and 42.9 wt% of the recyclable waste produced. At the same time, the questionnaire survey allows demonstrating that the SC behavior of the students improved considerably from 2018 to 2019, (t_[608] = -7.654, p < 0.05^***), as well as the satisfaction about the waste collection service provided (t_[608] = -6.6224, p < 0.05^***) and about the diffusion of information with awareness campaigns (t_[608] = -8.708, p < 0.05^***). The project and the phases followed for its implementation can be of reference for other local and international stakeholders, for replicating the study in other Universities and public areas. The novelty of the study is the introduction of a step by step methodology for assessing the SC of recyclable waste for supporting the recycling policies of developing cities in low-middle income countries and for boosting sustainable development according to the principle of the circular economy.

Waste Mismanagement in Developing Countries: A Review of Global Issues

Environmental contamination due to solid waste mismanagement is a global issue. Open dumping and open burning are the main implemented waste treatment and final disposal systems, mainly visible in low-income countries. This paper reviews the main impacts due to waste mismanagement in developing countries, focusing on environmental contamination and social issues. The activity of the informal sector in developing cities was also reviewed, focusing on the main health risks due to waste scavenging. Results reported that the environmental impacts are pervasive worldwide: marine litter, air, soil and water contamination, and the direct interaction of waste pickers with hazardous waste are the most important issues. Many reviews were published in the scientific literature about specific waste streams, in order to quantify its effect on the environment. This narrative literature review assessed global issues due to different waste fractions showing how several sources of pollution are affecting the environment, population health, and sustainable development. The results and case studies presented can be of reference for scholars and stakeholders for quantifying the comprehensive impacts and for planning integrated solid waste collection and treatment systems, for improving sustainability at a global level.