Costas Velis

• PhD MSc DIC MInstP MCIWM
• Lecturer at University of Leeds

A mess of plastic It is not clear what strategies will be most effective in mitigating harm from the global problem of plastic pollution. Borrelle et al. and Lau et al. discuss possible solutions and their impacts. Both groups found that substantial reductions in plastic-waste generation can be made in the coming decades with immediate, concerted,...

This paper presents an integrated modelling approach for value assessments, focusing on resource recovery from waste. The method tracks and forecasts a range of values across environmental, social, economic and technical domains by attaching these to material-flows, thus building upon and integrating unidimensional models such as material flow anal...

Solid recovered fuel (SRF), a partly biogenic form of waste-derived fuel, can be used for replacing fossil fuels in cement kilns. Higher SRF uptake is limited mainly by its chlorine (Cl) content. Here we present a systematic literature review (PRISMA methodology) on the challenges induced by Cl during SRF co-combustion in cement kilns. We show that...

Circular economy (CE) quantification features intrinsic complexity, mandating the application of systems thinking and associated methodologies to navigate multifaceted and dynamic intricacies; posing challenges for science-policy interfacing. Well-established approaches such as System Dynamics (SD) and emergent Agent-Based Modeling and Simulation (...

This paper communicates the main findings of a project which sought to improve the way that data on the activities of the informal waste sector are collected, and which has developed a preliminary model to quantify the contribution of the informal waste sector to the mitigation of plastic pollution in the Global South.

Rationale : The circular economy (CE) remains an elusive concept because stakeholders remain uncertain as to how it functions and delivers benefits; to industry and wider society. Aim: This work highlights how complexity arises in the CE system, and how to account those complexities to properly quantify different CE aspects. This will aid stakehold...

We uncover the systemic complexities of a polymer recycling chain insufficiently investigated, focusing on high-density polyethylene (HDPE) – a core contributor to plastics pollution in the Global South, via mismanaged waste. Rigid blow-moulded HDPE is widely used in retail packaging and fast-moving consumer goods containers; it is also sought-afte...

Negotiations for a global treaty on plastic pollution¹ will shape future policies on plastics production, use and waste management. Its parties will benefit from a high-resolution baseline of waste flows and plastic emission sources to enable identification of pollution hotspots and their causes². Nationally aggregated waste management data can be...

The United Nations have agreed to negotiate a legally binding instrument to eliminate plastic pollution which includes provisions to reduce environmental emissions of plastic through improved waste management. However, there is a paucity of scientific evidence to prioritize the actions which will have the greatest impact on plastic pollution mitiga...

The UN international legally binding instrument on plastic pollution (UNEA resolution 5/14) aims to reduce plastics pollution. However, midstream and downstream assessments show that optimizing waste management, removal technologies, and improved circularity is not sufficient to curb plastics pollution in the short-, mid- or long-term. Therefore, w...

Providing effective solid waste management (SWM) is essential to tackle plastics pollution, reduce greenhouse gas emissions and avoid other potentially harmful impacts, including local air pollution impacts from open burning and the conditions that spread disease. Official development finance (ODF) plays a key role in providing SWM waste infrastruc...

Why action to address solid waste management is both crucial and complementary to upstream actions in ending plastic pollution, and our proposal for how this should be addressed in the Plastics Treaty. Version 1 - relased in advance of the INC4 in Ottawa, Canada. Acknowledgements: We wish to acknowledge Professor David C Wilson’s guest blog for t...

A large global workforce of informal entrepreneurs has historically dominated circular economy practices in the Global South, collecting many millions of tonnes of waste for recycling, and supplementing insufficiencies in struggling municipal waste management systems. Ongoing negotiations for a ‘Legally Binding Instrument on Plastic Pollution’ impl...

Ongoing negotiations for a ‘Legally Binding Instrument on Plastic Pollution’ recognise the substantial contribution made by the informal recycling sector (IRS - waste pickers) to plastic pollution mitigation as part of just transition. Negotiating parties will require baseline evidence of the sector’s activities to inform the development of local a...

Negotiations for a Global Treaty on plastic pollution ¹ will shape policy on plastics production, use, and waste management for the coming decades. Parties will require a detailed baseline of waste flows and plastic emission sources at high resolution to enable identification of pollution hotspots and their causes ² . Nationally aggregated waste ma...

Identifying sources is crucial for proposing effective actions to combat marine litter pollution. Here, we used an innovative approach to identify hotspots of mismanaged plastic waste (MPW) within Brazil and subsequent leakage to the ocean, based on population density, socio-economic conditions, municipal solid waste management and environmental pa...

Mismanaged municipal solid waste (MSW), the major source of plastics pollution and a key contributor to climate forcing, in Global South cities poses public health and environmental problems. This study analyses the first consistent and quality assured dataset available for cities distributed worldwide, featuring a comprehensive set of solid waste...

Systems to safely store, handle, treat and dispose of medical (healthcare) waste are well developed in the 21st century. Yet, across many parts of the Global South (low-income and middle-income countries) such systems, resources and knowhow are lacking; to the extent that medical waste could pose a serious threat to the health, safety and lives of...

Recycling by the informal sector provides a rapid, inexpensive solution to plastic pollution, whilst supporting the livelihoods via their inclusion and empowerment. This solution will have the greatest benefit to the environment if supporting interventions are targeted at types of plastic pollution that are the most damaging from an ecological and...

The global plastics reprocessing sector is likely expand as the circular economy becomes more established and efforts to curb plastic pollution increase. Via a critical systematic scoping review (PRISMA-ScR), we focused on two critical challenges for occupational and public health that will require consideration along with this expansion: (1) Legac...

Over the coming decades, a large additional mass of plastic waste will become available for recycling, as efforts increase to reduce plastic pollution and facilitate a circular economy. New infrastructure will need to be developed, yet the processes and systems chosen should not result in adverse effects on human health and the environment. Here, w...

Despite the relatively benign characteristics of construction and demolition waste, its mismanagement can result in considerable harm to human health for 200 million workers and those who live and work in proximity to construction and demolition activities. The high number of workers classified as informal, results in a large unregulated and vulner...

Over the coming decades, a large additional mass of plastic waste will become available for recycling, as the world’s largest fast moving consumer goods companies step up efforts to reduce plastic pollution and facilitate a circular economy. Finding ways to recover value from this material is a substantial challenge that has prompted exploration of...

Despite the relatively benign material composition of construction and demolition waste (CDW), its mismanagement can result in considerable harm to human health, not only for the 200 million workers in the sector but also for those who live and work in proximity to construction and demolition activities. The population and workforce in low- and mid...

The critical functionality provided by the informal e-waste recycling sector to the global circular economy is marred by the hazardous emissions from this practice when it is carried out under informal and unregulated conditions in the Global South. Here, we focus a systematic review (PRISMA) of evidence specifically on rudimentary thermal processi...

Across the Global South, electrical and electronic waste (e-waste) is recovered using rudimentary and often dangerous methods in informal and unregulated facilities. Although these activities provide a valuable contribution to the global circular economy, their uncontrolled nature results in a risk of potentially hazardous substance emission into t...

Increasing aspirations to develop a circular economy for waste plastics will result in an expansion of the global plastics reprocessing sector over the coming decades. Here we focus on two critical challenges within the value chain that as a result of such increased circularity may exacerbate existing issues for occupational and public health (1):...

Large quantities of mismanaged plastic waste threaten the health and wellbeing of billions worldwide, particularly in low- and middle-income countries where waste management capacity is being outstripped by increasing levels of consumption and plastic waste generation. One of the main self-management strategies adopted by 2 billion people who have...

Systems to safely store, handle, treat and dispose of medical (healthcare) waste are well developed in the 21st century. Yet across many parts of the Global South (low- and middle-income countries) such systems, resources and know-how are lacking; to the extent that medical waste could be posing a serious threat to the health, safety and lives of m...

Disposal on land has persisted as the most predominant form of waste disposal for millennia and despite advances in modern engineered landfills, large quantities (405 Mt y-1) of collected municipal solid waste (MSW) are still deposited and concentrated in open, uncontrolled dumpsites throughout low- and middle-income countries (LIMICs) worldwide –...

Thermogravimetric analysis (TGA) is the most widespread thermal analytical technique applied to waste materials. By way of critical review, we establish a theoretical framework for the use of TGA under non-isothermal conditions for compositional analysis of waste-derived fuels from municipal solid waste (MSW) (solid recovered fuel (SRF), or refuse-...

The uncertainty arising from laboratory sampling (sub-sampling) can compromise the accuracy of analytical results in highly inherent heterogeneous materials, such as solid waste. Here, we aim at advancing our fundamental understanding on the possibility for relatively unbiased, yet affordable and practicable sub-sampling, benefiting from state of t...

The level of uncertainty during quantification of hazardous elements/properties of waste-derived products is affected by sub-sampling. Understanding sources of variability in sub-sampling can lead to more accurate risk quantification and effective compliance statistics. Here, we investigate a sub-sampling scheme for the characterisation of solid re...

Oil-Based Mud (OBM) cutting is a hazardous by-product generated during oil-well drilling. Its chemical composition suggests that it might be suitable as a raw material in cement manufacturing. It is rich in calcium oxide, silica, and aluminium oxide, which are the major oxides in raw materials for cement manufacturing. In this research, OBM cutting...

Running from 2015 to 2019, the Resource Recovery from Waste (RRfW) programme is a £7m strategic investment by NERC, ESRC and Defra to deliver strategic science in support of a paradigm shift in the recovery of resources from waste, driven by benefits to the environment and human health, rather than economics alone. The end-of-programme brochure ou...

Here we investigate the increasingly complex relationship between the resource recovery practices of the UK concrete industry and ongoing low-carbon transitions taking place in electricity and steel. Reductions in UK coal-based electricity and primary steel production are reducing domestic availability of residues – coal ash and steel slag – that a...

Over the last 60 years plastics production has increased manifold, owing to their inexpensive, multipurpose, durable and lightweight nature. These characteristics have raised their demand that will continue to grow over the coming years. However, with increased plastic materials production, comes increased plastic material wastage creating a number...

The European Commission (EC) recently introduced a 'Circular Economy Package', setting ambitious recycling targets and identifying waste plastics as a priority sector where major improvements are necessary. Here, the authors explain how different collection modalities affect the quantity and quality of recycling, using recent empirical data on hous...

The transition to a circular economy, where the value of resources is preserved in the technosphere, must be supported by policies and operational decision making based on evidence. Existing methods used to provide this evidence (e.g. LCA, LCSA, CBA) are not robust enough to adequately address the creation and dissipation of systemic and multidimen...

Established assessment methods focusing on resource recovery from waste within a circular economy context consider few or even a single domain/s of value, i.e. environmental, economic, social and technical domains. This partial approach often delivers misleading messages for policy and decision-makers. It fails to accurately represent systems compl...

How academics from the University of Leeds and waste management practitioners jointly co-create the next generation of analytical and decision support tools to maximise the gains delivered by resource recovery from waste in a more convenient, transparent and holistic way.

It is commonly accepted that the recycling and reuse of solid waste materials in developing countries has the potential to create many social, environmental and financial benefits. Given that the majority of recycling in these locations is carried out informally by waste pickers, it is also recognised that their inclusion into formal service provis...

The power plant sector is adopting the co-firing of biomass and solid recovered fuel (SRF) with coal in an effort to reduce its environmental impact and costs. Whereas this intervention contributes to reducing carbon emissions and those of other pollutants related with the burning of fossil fuel, it may also result in hidden impacts that are often...

Purpose: Solid waste management systems in low and middle income countries typically include a multitude of actors with a wide variety of characteristics, which must be defined and understood for effective intervention. This study creates a typology of operational models observed within the informal and semi-formalised waste management and recyclin...

India faces major environmental challenges associated with waste generation and inadequate waste collection, transport, treatment and disposal. Current systems in India cannot cope with the volumes of waste generated by an increasing urban population, and this impacts on the environment and public health. The challenges and barriers are significant...

A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with green waste as a bulking agent. Two different variants of OMW compost were used in growth trials during the 2014 season in the UK, one twice composted and one that was composted three times. The composting was on a pilot scale in windrows. During the f...

Interventions that focus on protecting the environment and human health, have started to be incorporated in various sectors. One such intervention is the co-firing of biomass and SRF with coal in power plants. While this intervention contributes positively to reducing carbon emissions and other pollutants from the extraction and burning of fossil f...

A compost was produced by co-composting olive mill wastewater (OMW) and chicken manure (CM), with green waste as a bulking agent. Two different variants of OMW compost were used in growth trials during the 2014 season in the UK, one twice composted and one that was composted three times. The composting was on a pilot scale in windrows. During the f...

European Commission (EC) recently introduced a ‘Circular economy package’, setting ambitious recycling targets and identifying waste plastics as a key area where major improvements and focus is necessary. The importance of plastics as a landmark case for the circular economy is denoted by the significant report on ‘New plastics economy’ released by...

Historically, bilateral donors and multi-lateral development banks have provided relatively limited attention and funding to solid waste management issues in a development context. However, this situation is changing with there being a growing consensus that improving solid waste management conditions can address a wide range of development issues...

We take recycling for granted. After all, everybody ‘knows’ about it, and most likely, opportunity given, ‘recycles’: meaning, invests the time and effort to sort out and clean the material, placing it in the suitable recycling bin. However, whoever works in the waste and resources management sector knows well that this is just the beginning of a l...

Good decision-making about how we manage the waste we create is one of the most important contributions humanity can make to reducing its impact on the natural world. The Global Waste Management Outlook (GWMO) is being released at a critical moment, one where the world is considering a new regime to keep global warming to below 2 degrees above pre-...

In established linear systems the values of materials are often lost or dissipated into waste ending up in landfills. Europe is proposing a range of measures to accelerate the transition from these linear systems to a more circular economy along the full supply chain. This requires new ways of looking at traditional industrial systems and materials...

Globalization is one of the major challenges for the long-term sustainability of waste management. And vice-versa appropriate waste management is one of the key-conditions for a sustainable globalization. There is an increasing need to focus on the linkages between globalization and waste management, and to understand their nature. Recognizing that...

The relationship between globalisation as a dominant worldwide process and solid waste management activities on a local and global scale has not previously been investigated systematically. Increased international trade in the last few decades has reduced poverty in many developing countries and raised living standards and purchasing power. At the...

This paper addresses a major problem in international solid waste management, which is twofold: a lack of data, and a lack of consistent data to allow comparison between cities. The paper presents an indicator set for integrated sustainable waste management (ISWM) in cities both North and South, to allow benchmarking of a city's performance, compar...

Rapid urbanisation and increasing global consumerism are driving unprecedented levels of waste generation in low and middle income countries. This rising tide of waste represents an increasing environmental, social and economic burden, particularly for the poorer parts of society. In many parts of the world waste collection is still limited to more...

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Mixed colour waste glass extracted from municipal solid waste is either not recycled, in which case it is an environmental and financial liability, or it is used in relatively low value applications such as normal weight aggregate. Here, we report on converting it into a novel glass-ceramic lightweight aggregate (LWA), potentially suitable for high...

Here material flows and their contributions to fuel properties are balanced for the mechanical section of a mechanical-biological treatment (MBT) plant producing solid recovered fuel (SRF) for the UK market. Insights for this and similar plants were secured through a program of sampling, manual sorting, statistics, analytical property determination...

The UN-Habitat Integrated Sustainable Waste Management (ISWM) benchmarking methodology was applied to profile the physical and governance features of municipal solid waste (MSW) management in the former Soviet Union city of Bishkek, capital of the Kyrgyz Republic. Most of the ISWM indicators were in the expected range for a low-income city when com...

This paper uses the lens of ‘integrated sustainable waste management’ to examine how cities in developing countries have been tackling their solid waste problems. The history of related concepts and terms is reviewed, and ISWM is clearly differentiated from integrated waste management, used mostly in the context of technological integration in deve...

In low- and middle-income developing countries, the informal (collection and) recycling sector (here abbreviated IRS) is an important, but often unrecognised, part of a city's solid waste and resources management system. Recent evidence shows recycling rates of 20-30% achieved by IRS systems, reducing collection and disposal costs. They play a vita...

The revised Waste Framework Directive (WFD), introduced in 2008, allows efficient EfW facilities to be classified as an ‘energy recovery’ operation, if they meet certain criteria. The core of the evaluation relies upon the so called “R1 Formula“. R1-values higher than 0.60 for existing plants, or 0.65 for newly built, indicate that these plants per...

This paper presents a detailed review of municipal solid waste (MSW) and resource management in Bahrain, using the recently developed UN-Habitat city profile methodology. Performance indicators involve quantitative assessment of waste collection and sweeping, controlled disposal, materials recovery and financial sustainability together with qualita...

This paper uses the 'lens' of integrated and sustainable waste management (ISWM) to analyse the new data set compiled on 20 cities in six continents for the UN-Habitat flagship publication Solid Waste Management in the World's Cities. The comparative analysis looks first at waste generation rates and waste composition data. A process flow diagram i...

Solid recovered fuel (SRF) produced by mechanical-biological treatment (MBT) of municipal waste can replace fossil fuels, being a CO(2)-neutral, affordable, and alternative energy source. SRF application is limited by low confidence in quality. We present results for key SRF properties centered on the issue of chlorine content. A detailed investiga...

The move from disposal-led waste management to resource management demands an ability to map flows of the properties of waste. Here, we provide a comprehensive review of how mechanical-biological treatment (MBT) plants, and the unit processes that comprise them, perform in relation to management of material flows, while transforming inputs into out...

The carbon emissions trading market has created a need for standard methods for the determination of biogenic content (chi(B)) in solid recovered fuels (SRF). We compare the manual sorting (MSM) and selective dissolution methods (SDM), as amended by recent research, for a range of process streams from a mechanical-biological treatment (MBT) plant....

Biodrying reactor technology can be used within mechanical-biological-treatment (MBT) plants; engineering and process performance have been addressed previously (Velis et al., 2009). Biodrying is a variation of aerobic decomposition, using high aeration rates to dry and only partially stabilise input wastes. The reactor output (biodried matter) is...