Chapter 1

A New Perspective on a Global Circular Economy

A. P. M. Velenturf,*a P. Purnell,a L. E. Macaskie,b W. M. Mayesc and D. J. Sapsfordd
a School of Civil Engineering, University of Leeds, Leeds, UK, . E-mail: A.Velenturf@leeds.ac.uk
b School of Biosciences, University of Birmingham, Birmingham, UK, .
c Department of Geography, Geology and Environment, University of Hull, Hull, UK, .
d School of Engineering, Cardiff University, Cardiff, UK, .


Natural resource exploitation is accelerating in the face of resource decline, while at the same time people are generating ever growing quantities of wastes. Population and income growth drive up the demand for energy, materials and food. Four planetary boundaries that indicate a safe operating space for humankind may well have been crossed – climate change, land system change, biogeochemical loading and biosphere integrity – all directly linked to resource overexploitation. Resource exploitation has brought welfare to many people, but it is now infringing upon basic human rights such as clean water and a safe living environment. The management of resources needs to change radically from the linear take-make-use-dispose model to a more sustainable, circular model. This chapter introduces the global challenges within which an international movement towards a circular economy has emerged. It critically revisits views on circular economy and proposes a new model that recognises the complex nature of our resource flows. The Resource Recovery from Waste programme is introduced and an overview is provided of the contents of this book.


1.1 The Importance of a Global Circular Economy

Natural resource exploitation is accelerating in the face of resource decline, while at the same time people are generating ever growing fluxes of wastes and pollutants.1–3 Global resource use has grown from 23.7 billion tonnes in 1970 up to 70.1 billion tonnes in 2010, and simultaneously the global population has nearly doubled and the economy more than tripled.1 Per capita global material use increased from 7 tonnes in 1970 to 10 tonnes in 2010, indicating improvements in living standards in many countries. However, globally an estimated 11.2 billion tonnes of municipal waste was collected in 2010, roughly 2 tonnes for every person on the planet, and a similar amount of uncollected waste is anticipated to have been generated.4 Current global consumption levels and the associated over-reliance on waste disposal and emissions rather than reuse and recycling are unustainable. The ecological ceiling of planetary boundaries has been crossed and humanity is risking destabilisation of the geological conditions upon which our society depends.5,6 Nevertheless, the growing resource use has, for many people, strengthened social foundations, incomes and welfare. The long term well-being of people does however depend on a healthy environment, providing the resources that are necessary to meet basic human needs including access to clean water, food and shelter.7 However, resource extraction and waste production have now reached such a scale that they result in unprecedented environmental degradation, climate change and pollution – thereby violating basic human rights and needs.1,8,9 The boundaries to sustain long-term environmental and socio-economic stability have been crossed. Radical changes in the ways in which waste and resource flows are organised, i.e. the resource economy, are necessary.10

Minimisation of resource use and increased resource efficiency are necessary to limit the throughput of materials in the economy.1 Concepts such as zero waste, waste hierarchy and sharing economy are gaining ground and can be captured under the umbrella of ‘circular economy’ (Table 1.1). Given the diversity in conceptual roots it is unsurprising that circular economy has been described in more than a hundred ways.11,12 These diverse concepts all refer to making better use of resources,11 here introduced by the words of the Ellen MacArthur Foundation13: “Looking beyond the current ‘take, make and dispose’ extractive industrial model, the circular economy is restorative and regenerative by design. Relying on system-wide innovation, it aims to redefine products and services to design waste out, while minimising negative impacts. Underpinned by a transition to renewable energy sources, the circular model builds economic, natural and social capital.” Circular supply chains that minimise wastes and strive to reuse, repair and recycle where wastes cannot be prevented need to be more sustainable than the linear systems they replace (Table 1.1); the ability of circular economy to contribute to sustainable development has been broadly accepted yet requires further conceptual development supported by empirical evidence.14 Most production-consumption systems cannot circulate 100% of resources, for example due to quality losses and energy requirements, and hence new resource inputs from the natural environment will remain necessary even in a circular economy. Moreover, a transition towards a circular economy requires innovative technologies and business models as well as cultural change. It will take time to move away from our current linear and economic growth centred systems to more circular systems that promote a healthy environment and greater equality. In the transition phase, a circular economy needs to be realised that enables business development through greater resource efficiency and contributes positively to the environment and society by maintaining the technical value, i.e. the functional qualities15 of materials that circulate through the production-consumption system.16

Table 1.1 Key terminology.
Key terminology Description
Bioeconomy “The bioeconomy comprises those parts of the economy that use renewable biological resources from land and sea – such as crops, forests, fish, animals and micro-organisms – to produce food, materials and energy”.17
Biogeochemical process Transformations of inorganic and organic elements and compounds in the lithosphere, hydrosphere and atmosphere that are mediated, directly or indirectly, by biological (chiefly microbiological) entities.18
Circular economy “Circular economy systems keep the added value in products for as long as possible and eliminate waste. They keep resources within the economy when a product has reached the end of its life, so that they can be productively used again and again and hence create further value”.19
Cradle to cradle – technical and biological flows A design approach that seeks to regenerate natural systems through the integration of flows of materials in society (technical flows) with those in the environment (biological flows).20
Ecosystem services The services provided by ecosystems to the benefit of people. Four types of ecosystem services have been defined: provisioning services (e.g. food, water); supporting services (e.g. soil formation, nutrient cycling); regulating services (e.g. climate, water quality); and cultural services (e.g. recreation, aesthetics).7 It is increasingly common for economic values to be associated with each service, based on e.g. the social costs avoided, or the replacement costs should such services be supplied by engineered systems.
Ecosystem stewardship People are an integral part of the ecosystem and carry a responsibility to manage the environment such that resource use is compatible with the capacity of ecosystems to sustain services.7
Linear economy An economy dominated by behaviour in which materials are extracted from the biophysical environment, fashioned into products using non-renewable energy sources, and disposed of after use as a waste without any form of recovery.
Multi-dimensional value A combination of economic (e.g. monetary price or worth of a resource), social (e.g. contribution to quality of life), technical (e.g. functional characteristics of a material or product) and environmental (e.g. contribution to biodiversity) values that each may be positive (benefits) or negative (costs). These must be considered holistically e.g. by using recognised multi-criteria decision analysis tools.15
Natural and Industrial materials Natural materials located in a biophysical environment that is not directly controlled by people; it may be of natural or engineered origin and participate in naturally occurring geological, chemical and biological processes without causing environmental harm. Industrial materials are resources transformed in the production-consumption system and ideally would be engineered in a way that enables reintegration into natural processes without negative environmental consequences upon return into the uncontrolled biophysical environment but may not be able to participate safely in such processes without remedial treatment.21
Natural capital “The world's stocks of natural assets which include geology, soil, air, water and all living things” providing ecosystem services.22
Planetary boundary Outline of the ‘safe operating space’ for humanity in different aspects of the earth system. Crossing these boundaries could cause catastrophic environmental change, destabilising global ecosystems into states that are less desirable for people.5
Production-consumption system The industrial system of production and use of materials and products as well as services, from resource extraction throughout the life-cycles of materials and products and, ultimately, disposal and possible return to the biophysical environmental (Figure 1.2).
Sustainable development Sustainable development is most commonly defined as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”.23
Sustainable development goals The 17 global goals in the United Nations’ 2030 Agenda For Sustainable Development.24
Waste and by-product valorisation The process of reusing, recycling or reprocessing to gain value from a waste, by-product or its constituents.
Waste hierarchy A tool to promote better resource use by prioritising waste prevention, followed by reuse, recycling, other recovery and disposal.25

1.2 Visualising the Circular Economy

The circular economy is depicted with the widely referenced butterfly diagram (Figure 1.1) that was developed by Braungart and McDonough20 for the Ellen MacArthur Foundation.26 The diagram shows separate ‘biological’ and ‘technical’ materials flows. ‘Technical’ materials are finite and are used in a closed loop system through sharing, maintaining, reusing, remanufacturing, and recycling of products. Conversely, ‘biological’ materials are renewable and organised in an open loop system of resources cascading through subsequent steps of extraction, production of bio-based materials, energy recovery, and returning nutrients to the biosphere to feed the next production cycle of primary crops. The Ellen MacArthur Foundation has catalysed a global movement towards circular economy, inspiring governments and companies around the world (read more about this in Chapter 16, Purnell et al.). The butterfly diagram has been pivotal in attracting stakeholders from all strata of society to the circular economy movement.

Fig. 1.1 Simplified butterfly diagram. Right: technical materials. Left: biological materials.26

There are, however, important shortcomings of the butterfly diagram that are becoming apparent during the implementation of circular economy practices. First, input of primary resources into the economy will be necessary, yet the extractive and initial material processing sectors (major consumers of energy and hence producers of CO2) are largely excluded from the diagram. It is important to consider these sectors as part of the circular economy because they are globally the largest waste producers and energy consumers. The circular economy principles of designing production-consumption systems that are restorative and regenerative by design could significantly minimise negative environmental and social issues.27,28 Second, materials and products typically contain more than one type of resource by nature or design, i.e. the biological and technical materials, as currently interpreted in practice, do not flow in separate cycles and are often mixed.21 Both points will be explained further in the next paragraphs.

1.2.1 Demand for Primary Materials for the Global Economy

New primary resources will have to be introduced into the global economy. The circulating of materials through the economy through consecutive cycles is associated with unavoidable losses of material quality and requires energy for resource recovery processes.29,30 New inputs will be needed to replace lower quality materials and to meet energy demands of resource circulation, unless the global economy embraces reduced consumption and the sharing of products at scale. The forecasts are, however, that significant natural reserves will be exploited for the growing global economy.2,31

Economic development and population growth already contributed to natural resource extraction rising 23-fold from 1900 to 2010 and this trend is forecast to continue.32 Exploitation of natural resources is expected to increase, with energy demands expected to double in the period 2014–2040 resulting in a growth of extracted oil (12%), natural gas (49%) and coal (5%), and demand for steel and copper reaching 120% in 2040 compared to 2010.2 Even the growth of sustainable industries can increase pressure on natural resources and the shift towards renewable energy for example will escalate demand for base and (near) critical metals.33

Half of the extracted resources will be stocked for long periods in infrastructure and will not be readily available for recovery. Moreover, large proportions of extracted resources are used as energy carriers and consequently the recovery of the technical value of the materials is not a priority.27 Haas et al. estimated that in 2005 62 Gt materials were processed globally, 13 Gt entered the waste stream and only 4 Gt were recycled.27 About 6% of materials enter the waste stream directly at the energy-intensive extraction phase. The primary sector, covering the extraction of raw materials including mining, mineral extraction, agriculture, fishing and forestry, is the most wasteful sector in our economy and, perhaps counterintuitively, this is an area where much can be gained from resource and energy efficiency in the quest for a sustainable circular economy.

1.2.2 Integrated Resource Flows

The interpretation of the technical and biological wings of the butterfly diagram has strayed away from a reality that largely consists of materials that contain combinations of ingredients from organic origin, minerals, metals, aggregates and water. Consider for example naturally occurring materials such as mineral and metal ores, soils and living organisms, and materials that become integrated during extraction, production, consumption and disposal, such as acid and metal mine drainage, car components, paints, sewage water and bioenergy residues (e.g. ashes and digestates).

In their cradle-to-cradle philosophy (Table 1.1), Braungart and McDonough20 originally distinguished biological and technical nutrients and these were defined as materials required by the biosphere and the technosphere (system of industrial processes) respectively. Biologically available nutrients could be organic or inorganic and were described as materials or products “designed to return to the biological cycle by being consumed by micro-organisms in the soil and by other animals” (p. 105).20 Technical materials were designed to stay within the technosphere only, but it was recognised that materials that can be harmful to the environment (e.g. metal- and mineral-based products) enter organic matter and water flows.

The butterfly diagram was directly based on the cradle-to-cradle philosophy, but the biosphere was depicted purely as the source of organic resources and omitted the role of the biophysical environment in (re-)circulating other materials that are essential for society (e.g. water, aggregates, minerals, and metals). The bioeconomy community continued to build on this image and adopted the biosphere wing as being the ‘bioeconomy’ part of the circular economy (e.g. ref. 34 and 35). However, materials from the bioeconomy (Table 1.1) become mixed with technical materials.36

The current interpretation of separate biological and technical flows does not align with the natural biophysical processes or practices in production-consumption systems. Going back to the roots of cradle-to-cradle,20 the Resource Recovery from Waste Programme (see Section 1.3) proposed a new model for circular economy21 (Figure 1.2): The production-consumption system is embedded in the wider biophysical environment, recognising people as an integral part of the environment. People extract natural materials from the biophysical environment, and transform, use and dispose of industrial materials within the production-consumption system. Both natural and industrial materials (Table 1.1) can contain combinations of organic materials, minerals, metals, aggregates and water. At end-of-use, materials and products can be directly circulated back into the production-consumption cycle or they can be stored in a controlled environment in resource recovery systems. The latter can use artificially strengthened, natural processes to recover materials and leave no other materials than those that can be used by industry and/or safely returned to the uncontrolled biophysical environment (examples of such resource recovery systems are introduced in the next section and described throughout this book). Industrial materials that are no longer required for production should be safely returned to the biophysical environment, surrendering materials to natural geological, chemical and biological processes and reintegrating them into natural capital reserves that can supply future production-consumption cycles. This new model of a circular economy that embraces the mixed nature of materials offers an effective starting point for the development of government strategy, business practices and innovative resource recovery technologies and systems that aim to valorise complete waste matrices instead of recovering just one type of material and letting the residues dissipate into waste. Once dissipated in the environment, resources may be lost to humankind for the foreseeable future as re-formation of new ore bodies would occur on a geological timescale.

Fig. 1.2 Simplified integrated resource flow model for the circular economy. Green arrows indicate natural materials; thin arrows indicate industrial materials.21

1.3 Resource Recovery from Waste

The Resource Recovery from Waste programme developed technologies and systems that can recover different types of materials from mixed waste matrices, aiming for zero waste residue and requiring limited external energy input.21 Resource Recovery from Waste is a strategic investment by the Natural Environmental Research Council, the Economic and Social Research Council and the Department for Environmental, Food and Rural Affairs in the United Kingdom (UK) in response to the global challenge of having to bring resource exploitation and waste generation within the planet's environmental limits. The purpose of the programme was to contribute to radical change in waste and resource management, driven by environmental benefits (such as water and soil quality) and social benefits (such as human health) rather than by economics alone. From 2014 until 2019, six research projects were delivered while various cross-cutting and overarching projects supported knowledge exchange and the development of coherent, accessible outcomes for all stakeholders involved in the programme – from academia to companies and government bodies inside and outside the UK. The projects can be divided into those focusing on organic wastes and by-products and those with a scope on metal-bearing wastes; but bear in mind that all projects aimed to recover complete mixed waste matrices with diverse organic and/or inorganic materials.

The first group focusing on organic wastes comprises the projects designated Adding Value to Ash and Digestate (AVAnD), Microbial Electrochemical Technology for Resource Recovery (MeteoRR) and Beyond Biorecovery (B3). Organic waste recycling is discussed in Section 1 of this book. The AVAnD project worked with residues from bioenergy processes. The aim was to blend soil conditioners from digestates of anaerobic digestion and ash from the thermal conversion of wood waste. Digestates and ash have complementary nutrient profiles and this characteristic could benefit agriculture. A number of different blends of the materials were tested for effects on crop productivity, soil health and nutrient cycling. You can read more about this project in Chapters 5 and 12. The MeteoRR project aimed to improve the technical basis for resource recovery from wastewaters using microbial electrochemical technology, providing a more sustainable and cost-effective approach to industrial wastewater treatment. The research is intended to develop bioelectrochemical systems (BES) which use microorganisms to harvest the chemical energy available in wastewater to drive parallel processes such as the recovery of useful metals from wastewater, including novel nanometallic structures, and the synthesis of valuable organic compounds from carbon dioxide. Results from the MeteoRR project are shared in Chapters 4 and 10. The B3 project builds on the principle that bacteria can recover precious metals (PMs) from acid leachates and these recovered materials can be processed into innovative catalysts. The project developed bio-PM neo-catalysts that are biorefined from materials such as road dust and industrial wastes. These catalysts aim to offer more environmentally sustainable and cost-effective alternatives to catalysts depending on critical raw materials such as platinum group metals. They are used for the catalytic upgrading of, for example, heavy fossil oil and pyrolysis oil. Chapters 3, 9 and 13 present results from the B3 project.

The second group focused on metal recovery and the simultaneous remediation of land and water, and includes the Resource Recovery and Remediation of Alkaline Wastes (R3AW) and In situ Processes in Resource Extraction (INSPIRE) projects. Recovery from metal-bearing waste is discussed in Section 2 of this book. Metal-rich wastes from mining and refining are major global waste products, yet are often omitted from discussions about the circular economy that tend to focus on post-consumer wastes. The R3AW project investigated alkaline industrial bulk wastes such as slag from the steel industry and red mud from the alumina industry. The project researched the biogeochemistry of alkaline wastes and used this knowledge to develop predictable, passive remediation and metal recovery technologies. In this way, vanadium and various other materials can be recovered from steel slag and red mud, environmental emissions can be minimised, and the scope for reuse of bulk material in the residue matrix can also be enhanced. Results from R3AW are shared in Chapters 7 and 15 where the hidden values in some wastes associated with carbon capture and the development of conservation sites are also highlighted. These additional values are also explored in the INSPIRE project which investigated the challenges and potential of secondary mining of industrial and mining waste repositories. Various approaches employing microbes and engineered nanomaterials were investigated for recovery of pollutants such as copper, arsenic and lead, and to make matrices of inorganic, mineral and organic wastes more amenable to recovery operations. Chapters 2, 8 and 11 present conceptual developments and outcomes from the INSPIRE project.

It is vital that the newly developed circular technologies are more sustainable than the linear techniques they replace. Sustainability assessments were carried out and while some projects stuck to the well-established method of life-cycle analysis (see Chapters 4 and 13), the Complex Value Optimisation for Resource Recovery (CVORR) project developed a new approach through a new analysis framework that both looks beyond single domains of value – most current methods concentrate solely on environmental (Life Cycle Analysis, LCA) or technical (Materials Flow Analysis, MFA) value – and takes a system-based approach, looking upstream and downstream of the waste generation point in the supply chain, rather than focussing on ‘end-of-pipe’ strategies. The approach analyses how environmental, social, economic and technical values are created, transformed, preserved and lost throughout supply chains. The complete framework, including an example on pulverised fly ash, is outlined in Chapter 14.

1.4 Integrated Recovery of Organic and Inorganic Materials

This book demonstrates the depth and breadth of knowledge developed within the Resource Recovery from Waste programme. It presents emerging bio-related technologies and applications for resource recovery in enabling a global circular economy. A particular focus of the programme concerns high volume wastes associated with primary production processes such as organic wastes in the energy and agriculture sectors and inorganic wastes associated with mining, refining and major industrial process wastes. These ‘pre-consumer’ wastes are often overlooked in the current thinking about circular economy (as demonstrated in Section 1.2) which focuses on post-consumer wastes such as plastic packaging. The Resource Recovery from Waste programme adopted a holistic perspective on the complete production-consumption system from resource extraction to manufacturing, consumption, waste management, and the controlled storage and gradual return of materials into the environment, thereby feeding them back into natural capital reserves that may be exploited again for future cycles of production and consumption.21 Sections 1 and 2 of the book summarise the state of the art in resource recovery technologies for two classes of wastes and by-products: organic and metal-bearing. These sections highlight information gaps in applying novel technologies and the requirements to facilitate their full-scale deployment. Alongside advances in resource recovery technologies, governance of waste and resources is key to enabling progress towards a circular economy. Current governance is appraised in the final chapters of the book along with recommendations for future alternatives to facilitate the implementation of innovative resource recovery technologies discussed in earlier chapters.

1.4.1 Organic Wastes and By-products

Resource Recovery from Waste projects with a focus on organic waste streams have been developing integrated systems that use novel biogeochemical processes to recover materials with the use of energy and/or microbes extracted from the waste streams. Orozco et al. (Chapter 3) for example developed a bioenergy-biorefinery system to convert food wastes and municipal wastewater into hydrogen via fermentation processes that are supported by biocatalysts produced from the same waste streams. The use of catalysts reduces energy demand of the resource recovery process. Energy costs were also important drivers for Christgen et al. (Chapter 4) who present an integrated technology that uses innovative bioelectrochemical systems (BES) to process industrial, municipal, and agricultural wastewaters, generating energy and recovering metallic and organic resources. Selective metal recovery with electrochemical methods would normally have a high external energy demand. However, with the use of BES, the current generated during the recovery process improves the energy efficiency of resource recovery significantly.

Moreover, innovations replacing the abiotic cathodes with organic ones add further catalytic benefits that result in improved quantities and qualities of the recovered materials. Rashid and Bugg (Chapter 2) delve into the fine detail of the biological mechanisms behind biodegradation with the active deployment of microbes such as fungi and bacteria, and their enzymes, to speed up the delignification of woody agricultural and municipal wastes for the production of biogas and renewable chemicals. Integration of the generation of bioenergy with material recovery offers a valuable opportunity to restore soils (Lag-Brotons et al., Chapter 5). Anaerobic digestion is increasingly deployed for the processing of agricultural, industrial and municipal food wastes. Growing volumes of digestates are produced that, when mixed with ash from industrial waste-wood combustion, can result in a soil conditioner with a more balanced nutrient profile for plants than individual bioenergy residues generate on their own.

Deployment of integrated recovery systems for organic wastes can deliver environmental, technical, and economic benefits that respond to the sustainability challenges outlined in the first section of this chapter: Environmental: The use of organic materials can reduce the use of synthetic fertilisers and the energy inherent in their production, with benefits related to the planetary boundaries of climate change and nitrogen and phosphate flows.6 Moreover, in contrast to synthetic fertilisers, organic fertilisers also support soil restoration through improved structure and organic matter content (Lag-Brotons et al., Chapter 5). The proposed treatments prevent dissipation of materials into waste and the associated potential negative environmental impacts such as greenhouse gas emissions and water pollution. A final environmental benefit is the strengthened energy and resource security, crossing over into the economic benefits of supply security. Economic: Economic benefits are related to resource security by increasing certainty regarding the qualitative characteristics of resource flows (in other words, their technical value) after treatment, thereby increasing monetary value or at least lowering the costs for waste treatment and the sourcing of input materials. Other economic benefits pertain to the increased speed of resource recovery with the dual benefit of being able to sell more recovered resources per time unit and, in the case of cleaning up landfills, making land available for redevelopment sooner. Technical: Technologies discussed in this first section of the book enhance the recovery of resources and their qualitative characteristics, such as the delignification of waste streams ahead of further processes to recover materials. In other cases the energy originally invested in the production of the organic materials can be recovered. Finally, technologies such as BES can separate organic and metal-bearing resources, increasing the number of different materials that can be recovered for higher value applications.

There are two persistent challenges that need to be solved if these values are to be realised. First, significant variation in waste composition poses challenges for designing the right mixtures of microbes to process the wastes. Building on that, we still face knowledge gaps regarding the nutritional requirements of microbes; a better insight into their needs would help fine-tune which wastes they can digest. The variation in waste inputs creates a knock-on effect, resulting in a wide range of qualitative characteristics of recovered materials. This creates challenges during commercialisation, given that manufacturers tend to demand materials with narrow qualitative specifications. Real-world applications and upscaling are general challenges that require further research to cover issues such as product formulation and larger scale pilot studies for the developed technologies.

1.4.2 Metal-bearing Waste Materials

Projects within the Resource Recovery from Waste programme have been building on a long tradition of using microbial technologies to recover metal resources that dates back to the 1970s (Murray et al., Chapter 9). Driven by growing resource scarcity and market prices, the purpose for the deployment of these types of biotechnologies is shifting from environmental remediation to recovery. Metal recovery from mixed waste matrices remains a technically challenging, energy-intensive and economically costly process. With that in mind, various Resource Recovery from Waste projects have developed new bio-based catalysts and engineered nanomaterials. Murray et al. (Chapter 9) and Archer et al. (Chapter 13) share their experiences in their quests for low-grade, effective, and bio-based metallic nanoscale catalysts. Waste streams such as road dust, industrial wastes and furnace linings contain platinum group metals that can be synthesised into neo-catalysts with waste microorganisms from the bioremediation, pharmaceuticals and food industries into novel catalysts for upgrading bio-based and mineral oils. Lloyd et al. (Chapter 10) also developed new biogenic precious metal nanoparticles for use as catalysts to valorise organic wastes and/or as quantum dots to upgrade sunlight. As outlined in the first section of this book, such catalysts can be used for the recovery of organic and metallic resources in integrated biorefinery systems. Development of nanoscale technologies as discussed by Crane et al. (Chapter 11) demonstrates that such engineered nanomaterials can be utilised for the targeted recovery of valuable elements from wastewaters originating from municipalities, industries and mines. Wastes can be transported for treatment to a resource recovery facility, but in situ field application may be favourable as discussed by Sapsford et al. (Chapter 6), Gomes et al. (Chapter 7) and Roberts et al. (Chapter 8). In Chapter 7, Gomes et al. investigate technologies for the treatment of alkaline wastes such as steel slag and bauxite residue. Roberts et al. (Chapter 8) explore the capture of metals and organic pollutants from legacy landfills containing iron-oxide bearing sludges by using indigenous iron-reducing microbes. Large volumes of alkaline wastes are stored in the environment and bulk reuse, metal recovery and carbon storage in legacy landfills offer potentially complementary benefits.

The recovery of metals from the extractive and manufacturing industries can preserve environmental, economic, social and technical values, slowing down and in some cases reversing the negative sustainability trends discussed in the opening sections of this chapter. Environmental benefits include the following: Reduced air pollution: Particularly linked to dust, impacts on human health can be minimised with the right management although this comes at a financial cost. Reduced water pollution: The dissipation of metals into the environment from mining wastes and industrial landfills can persist for hundreds of years and, even in low concentrations, impacts can be severe and widespread. Resource recovery curbs water pollution and may at the same time open sources of (near) critical material supplies for clean growth (also see ref. 37). Reduced impact from raw material extraction: Supplies of recovered resources can slow down the demand for newly extracted metals, such as lithium, cobalt, copper, vanadium and tellurium, and thereby avoid environmental impacts from mining. If new materials must be extracted, then environmental impacts can be decreased with the use of the newly developed waste-based catalysts and nanomaterials. The use of such materials can also decrease the energy requirements of resource extraction and recovery, thereby reducing carbon emissions. Climate change mitigation: Carbon emissions can be stored in alkaline soils and silicate-rich wastes through weathering and carbonation.

Resource recovery can result in strategic economic benefits such as greater security of supply of (near) critical raw materials. With the potential value of recovered resources running into the millions of pounds annually, sales of recovered materials can positively impact companies’ bottom lines. However, such economic benefits need to outweigh the recovery costs. The costs of the resources needed to recover materials such as catalysts and energy can be minimised when producing supporting substances from wastes (such as reusing living cells in the cases of Murray et al., Chapter 9 and Archer et al., Chapter 13). Similar to organic wastes (Section 1.4.1), the variations in quality of waste supplies can pose challenges for the production process (such as in the case of road dust, Murray et al., Chapter 9), limiting the quality of the supporting substances and imposing detrimental impacts on the economic viability of the whole resource recovery operation. Low concentrations of materials in waste matrices that are to be recovered, such as copper from mine tailings and vanadium from steel slag, result in low volumes of recovered metals in any given unit of time and this issue continues to render these technologies economically unviable. Further research is needed (discussed below), and governance intervention can help in correcting such market failures through introduction of more ambitious resource recovery targets and a differential tax on carbon contents associated with the proportions of primary resources in products (also see ref. 38). Finally, technical values are key considerations in the upcycling of metal-bearing wastes. In order for new resource recovery technologies to gain traction they must be practical, scalable and robust and demonstrate favourable performance over current technologies.

Environmental, economic and technical aspects of the resource recovery developments discussed in this section require further research. Firstly, the technologies require further development and refinement in many cases, e.g. to improve the selective releases of metals from complex tightly bound waste matrices and the ability to capture mobilised resources. Mechanisms to remove recovered metals at the right time from the capturing agents also need further development. The challenges of dealing with low concentrations of target metals and recovering sufficient volumes to make the processes economically viable remain unsolved and tie into the challenge of scalability. Scale dependencies deserve high priority in future research including field pilot studies. Such studies can proceed only after the required environmental permits are secured, and this depends on the available evidence accounting for environmental risks. In the case of engineered nanomaterials, more preparatory research needs to be carried out. Additionally, assessments of impacts on human health and environment, together with economic business studies, must be presented. Such evidence is also needed when moving further up the technology readiness ladder, in order to convince regulators of performance and investors to provide vital capital. There must be a convincing case that the value of the recovered resources will outstrip the costs of the recovery process. This can be difficult due to volatile resource prices (and values afforded to carbon mitigation) and governments can help overcoming such challenges.

1.4.3 Governance for Resource Recovery

The final section of the book turns towards the governance of resources and wastes. The technical developments detailed in the first two sections are important in offering alternative approaches to valorise wastes and potentially reduce virgin resource use. However, new technologies face various challenges before they benefit from widespread societal uptake. Key amongst these are how resources and wastes are governed in the current linear economic model.

Marshall et al. in Chapter 12 explore governance and regulation across the arenas of bioenergy and food production. The use of alternative fertilisers and soil conditioners from bioenergy by-products (e.g. ash and digestates) provides an opportunity to minimise virgin resource use and make the most of wastes from energy generation. However, various regulatory barriers presently prevent the re-entry of these by-products into production cycles, driven primarily by conflicting regulations across different sectors of the economy. These potential obstacles are considered and recommendations for future policies are made in the light of regulatory uncertainty in a UK context.

Resource management has historically been governed by short-term economic drivers, where environmental costs typically associated with resource extraction and production processes are often unaccounted externalities. A full life-cycle approach to assessing novel resource recovery technologies is detailed in Chapter 13 by Archer et al. Through detailed accounting of environmental benefits associated with converting metallic wastes into novel catalysts (and the environmental costs associated with traditional production processes), the chapter demonstrates the relative merits of new technologies. Archer et al. argue for further incentive schemes that account for these broader environmental impacts to guide decision-making by investors and policy-makers.

Purnell et al. offer an alternative life-cycle assessment approach in Chapter 14 with the Complex Value Optimisation for Resource Recovery (CVORR) framework interrogating concrete-steel-electricity systems. Key to their approach is considering the technical values of resources during cycles of use and production, particularly accounting for these values in resource management. For example, change in one industrial sector that seemingly improves environmental performance can lead to unforeseen negative impacts on resource re-use in other sectors. Purnell et al. detail the example of the move from coal to biomass in electricity generation which adversely affects the reusability of flyash in cement products.

In Chapter 15, Deutz et al. highlight how decisions on potential resource management have been driven historically by environmental protection legislation for by-products of the steel industry. One barrier to potential resource recovery technologies in this setting concerns the definitions of wastes and the point at which wastes have been processed sufficiently to be considered products again. This has implications for reintroducing materials into the economy where resource recovery opportunities arise – a complex issue at sites handling or managing legacy wastes.

The concluding Chapter 16 by Purnell et al. provides an overview of drivers for knowledge uptake on resource recovery from wastes and how they conflict with current regulatory infrastructure and short-term economic drivers that determine our current patterns of resource use and consumption. The chapter sets out the short- and long-term needs for regulation of resources and wastes that would help facilitate a drive towards the circular economy and sustainable resource use.

Government change is crucial in realising a sustainable circular economy and the associated environmental, social, technical and economic values.16 Implementing a circular economy can bring various benefits to governments. First, it can significantly contribute to meeting obligations under international agreements such as the United Nations’ Sustainable Development Goals and critical issues such as climate change and renewable energy (Purnell et al., Chapter 16; Lag-Brotons et al., Chapter 5). Second, resource recovery can result in strategic economic benefits by increasing resource security, reducing supply risks, and minimizing impacts of global resource price volatilities. These factors are vital for sectors such as low-carbon infrastructure development and agriculture operations that depend on critical materials. Moreover, resource efficiency saves costs, for example by reducing waste management expenditures, and this money could be invested into further sustainable circular economy practices.16

Before governments can reap the benefits of a circular economy, a number of governance challenges have to be addressed – as identified by the authors of this book: Governance for circular economy should cover the complete production-consumption system including the extractive and raw material processing industries. There is a need for innovative governance interventions such as alternative, transparent and affordable regulatory mechanisms that can enable the safe return of secondary materials into new production cycles (Gomes et al., Chapter 7; Marshall et al., Chapter 12), and an updated waste hierarchy that integrates material selection principles (Purnell et al., Chapter 16). The old regulatory culture rooted primarily in concerns for health and environment limits the potential for optimising production and consumption that also embraces the strategic economic benefits of greater supply security and the multi-dimensional values of secondary resources (Crane et al., Chapter 11; Marshall et al., Chapter 12; Deutz et al., Chapter 15; Purnell et al., Chapter 16). Effective operation of government is constrained by incomplete circular economy ‘infrastructure’ regarding data inventory and reporting systems, taxes on primary and secondary resources, solution-driven transdisciplinary research funding, diverse physical waste processing and resource recovery facilities, and cross-departmental bodies that can remove barriers caused by limited policy integration (Purnell et al., Chapter 16).16,39 Governance across international, national and regional scales differs widely, making it easy to displace impacts and move production and waste processing to locations with less stringent governance contexts (Crane et al., Chapter 11).40 Governments could solve this by making better use of existing initiatives with strong circular economy angles (see above), and by developing new (inter)national agreements that can offer consistent, ambitious long-term frameworks for a circular economy that provides governments and companies with the certainty required to make investment decisions in favour of more sustainable resource use (Deutz et al., Chapter 15; Purnell et al., Chapter 16). Both existing as well as missing policies and regulations can constrain the implementation of circular economy practices, such as a lack of ambitious waste prevention and recycling targets and a regulatory framework that enables the safe storage and transport of waste (Lag-Brotons et al., Chapter 5; Marshall et al., Chapter 12; Purnell et al., Chapter 16).40

Governments can and arguably should do more to enable a sustainable circular economy. There is broad consensus, however, that governments cannot deliver the radical changes that are required in isolation. Collaboration is key to implementing a circular economy. Joint actions of all relevant stakeholders across society, from government to companies, civil society and academia are critical. The following chapters provide overviews of the contributions made by the Resource Recovery from Waste programme to advance a sustainable circular economy on a global scale.

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