Targeted under NERC's Water theme, the proposed project is aimed at determining the fate, reactivity and environmental risk of deploying nanoscale iron particles (INP) for the cleanup of polluted sites and groundwaters around the UK. The project is CASE supported by URS/Scott Wilson with advisory input from DEFRA (Dr Helinor Johnston) and CL:AIRE (Dr John Henstock). The Problem: The increased development and use of engineered nanomaterials has the potential to offer great benefits to society through their exploitation within numerous products developed by diverse industries. Some applications of nanomaterials have the potential to afford environmental benefits and of particular interest is the use of nanoscale particles of zerovalent iron (INPs) for the in situ cleanup of contaminated land and groundwater. Theoretical and practical evidence suggests that these INPs can be used to rapidly remediate contaminated sites at a significantly reduced cost relative to conventional methods. Most significantly they are also applicable for a wide range of hazardous chemicals, including polychlorinated biphenyls (PCBs); heavy metals and even radionuclides. To date the UK government has adopted a precautionary approach to the deliberate release of nanomaterials into the environment and consequently the use of INP remediation technology is not currently permitted by the UK Environment Agency. In July 2010 DEFRA commissioned a study (CB0440) to evaluate whether the hypothesised or known detrimental effects associated with the intentional release of INPs into the environment, outweigh the benefits that may be realised by using INP for site cleanup. Whilst this study has not yet been completed, a recent detailed review provided by the Bristol group has highlighted that much is still unknown about the true geochemical fate of INP injected into the subsurface, their true efficiency for cleanup of pollutants and the level of impact they may have on the environment. The Solution: By partnering academia with industry, the current project proposes to bridge the gaps in our current understanding and provide valuable site-derived data relating to the lifecycle of INPs in the environment. The project will build upon existing links between the Bristol Interface Analysis Centre (IAC), a group with the strongest UK track record for INPs research, and URS/Scott Wilson, an internationally renowned geotechnical and geoenvironmental engineering consultancy. Over the period of the project, the student will perform both laboratory and field-based investigations using INP of different sizes and types (wet-formed, dry-formed, annealed, surfactant coated) to evaluate their relative performance for contaminant remediation in natural waters of complex geochemistry. The project will also seek to better understand specific fundamental lifecycle aspects of INP injected into pore-water systems, specifically the factors that control transport, transformation, contaminant-INP reactivity and microbial impact. Of specific value to the project, URS/Scott Wilson will provide access to contaminated sites within the UK and/or overseas where the student, under supervision of the CASE supervisor, will participate in the planning, deployment and monitoring of a remediation project using INP. In the UK the student will also have access to a specialist 50m3 hydrogeochemical test cell located at URS/Scott Wilson's laboratories in Nottingham, where groundwater remediation systems using INP's will be prototyped and optimised. It is considered that the current studentship, which will be advised by both DEFRA and CL:AIRE, will produce data and practical knowledge that will help to shape future UK legislation and industry best practice for the use of INP in site clean-up.

Historical disposal of wastes from domestic and industrial sources often took place with little regard for potential environmental impacts. Wastes were often deposited in landfills that can release potential pollutants to the surrounding environment. Such 'legacy landfill' sites are a particular concern in coastal areas where they are likely to be affected by increased flooding, greater erosion and more extreme cycles of wetting and drying as our climate changes. Managing such environmental issues is of critical importance, but currently we do not have a systematic framework by which we assess and understand the nature of the risks posed by different waste types in coastal areas. Given the UK's rich industrial past, there are a wide range of legacy wastes deposited in estuarine and coastal settings such as municipal waste, mine wastes, steel industry by-products, metal-rich wastes from smelting and chemical process wastes. This proposal brings together a team of researchers specialising in assessing the environmental risks of legacy wastes to (1) provide a national assessment of the environmental risks associated with legacy landfills in the coastal zone, and (2) provide a framework for effective management of these risks now and in the future. The first part of the project will bring together various national databases (e.g. on location of landfills, mining waste, coastal erosion rates, coastal management plans) to provide a single map-based database of legacy landfills within the coastal zone. We will then liaise with regional specialists in government agencies and academia to collate detail on documented risks and identify high risk priority sites (e.g. those with the greatest contamination risk and / or those most affected by erosion or flooding). This will allow us to produce an overview of the different types of waste in coastal landfills, assess the broad risks posed by them (e.g. pollutant release, physical erosion etc.) and consider potential options for resource recovery from these sites (e.g. scrap metals that could be recycled). The second component of the project will improve our understanding of the environmental behaviour of different waste types in coastal settings. Most risk assessments for wastes are undertaken assuming they will be in contact with freshwater (e.g. leaching tests that simulate wastes in contact with rainfall). We will provide a significant advance on assessing environmental risks in coastal settings by testing how pollutants are released from different waste types (e.g. municipal waste, mine waste, processing wastes) under a range of environmental conditions. These conditions will simulate the current and future environmental scenarios in coastal areas such as variations in salinity and extremes of wetting and drying that are anticipated with climate change. Crucially, we will undertake experiments that test how these wastes behave across a range of experimental scales (e.g. from beaker sized experiments, through skip-sized experiments, to measurements at real sites). This is important to have confidence that small scale laboratory experiments give us information on how pollutants are released from waste that matches with data from real field sites. Such information is crucial for extending the risk assessments completed in part one of the project. Effective long term management of legacy wastes relies on many different agencies working together (e.g. councils, regulators, land owners, engineers). The final part of the project will therefore bring various stakeholders together in different parts of the UK to (1) evaluate approaches to remediation, and (2) consider management priorities put forward by the early stages of the project. A series workshops will take place in the different administrations of the UK to produce a national management framework for legacy wastes in the coastal zone.

Over half a billion tonnes of alkaline (i.e. bleach-like) wastes are produced globally each year by industries such as steel production, alumina refining and coal-fired power generation. These wastes are currently stored in piles or landfill and can pose serious environmental hazards. Water that filters through the waste is toxic to aquatic life and dust generated as it is moved and stored is a public health hazard. It can take decades for these risks to fade. On the other hand, alkaline wastes contain large quantities of materials we would like to recover for re-use, particularly metals important to the technologies of the future, such as vanadium, used in steel manufacture for offshore wind turbines, lithium and cobalt for vehicle fuel cells and rare earth elements crucial for next-generation solar power systems. The obvious solution: using the profits from recovering resources locked in the waste to pay for remediation of the pollution, is hampered by the environmental damage caused by digging up stored waste piles and the expense of extracting the metals from the waste using existing technology. Ground-breaking pilot research recently conducted by the team proposing this project shows that harnessing the power of low-cost, low-energy natural processes could solve the problem. We are developing a unique 'biomining' approach to increase the rate at which resources stored in the waste dissolve into water passing through it. Our pilot tests have shown that covering the waste pile with a layer of 'solid municipal waste' (compost) is very effective in driving this process. As water flows through waste treated with compost, metals like vanadium leach out to levels over twice those of untreated piles. The metal solution then flows out of the bottom of the waste pile under gravity. The high concentrations mean that extracting metals from this solution becomes viable using existing technology which we propose to implement as part of this project. In effect the valuable resources are extracted without digging up the waste. The resource recovery benefits are matched by benefits to the environment. The layer of compost reduces dust generation from the site, and allows more CO2 to penetrate into the pile where it is locked away in significant quantities by reacting to form solid carbonate minerals. As elements like vanadium are pollutants as well as resources, recovery will eliminate the pollution alkaline waste weathering causes. Furthermore, the weathered waste piles have ideal conditions for nationally-scarce, orchid-rich plant communities to become established, making them suitable for restoration to create habitat of high conservation value. In order to turn the extremely promising results of our pilot studies into optimised, industry-ready processes we must better understand the specific mechanisms which control the biomining and develop a road map for negotiating the economic, legislative, environmental and societal challenges to the implementation of a new technology in an established industry with strict requirements for environmental protection. Our proposed research will tackle both these aspects in parallel. The combined package: recovery of the metal resources while suppressing dust, increasing carbon sequestration and treating the pollution caused, would be hugely beneficial to partners in our project from both industry (Tata Steel, Rio Tinto and the Minerals Industry Research Organisation) and environmental protection (Environment Agency). The project will bring together key commercial partners with a multi-disciplinary team of environmental scientists, waste policy experts and specialists in systems analysis and stakeholder engagement to pave the way for transforming resource recovery and environmental remediation. This team will investigate the key obstacles to this transformation and identify potential remedies, such as lobbying for legislative change or making a clear business case for resource recovery.

177 million tonnes of virgin aggregates, 15 million tonnes of cement and 2 billion bricks were used to build houses, civic and commercial buildings, roads and railways, etc, in the UK in 2016. Meanwhile, 64 million tonnes of waste arose from construction and demolition. Materials from construction and demolition are mainly managed by down-cycling with loss of the value imparted to them by energy-intensive and polluting manufacturing processes; for example, high value concrete is broken down into low value aggregate. Environmental damage is associated with the whole linear life cycles of mineral-based construction materials, and includes scarring of the landscape and habitat destruction when minerals are extracted from the earth; depletion of mineral and energy resources; and water use and emission of greenhouse gases and other pollutants to air, land and water, during extraction, processing, use and demolition. It is important to take action now, to return materials to the resource loop in a Circular Economy, and reduce the amount of extraction from the earth, as the amount we build increases each year. For example, the UK plans spend £600 billion to build infrastructure in the next decade. The UKRI National Interdisciplinary Circular Economy Research Centre for Mineral-based Construction Materials therefore aims to do more with less mineral-based construction materials, to reduce costs to industry, reduce waste and pollution, and benefit the natural environment that we depend on. There is potential for mineral-based construction materials to be reused and recycled at higher value, for example, by refurbishing rather than demolishing, or by building using reusable modules that can be taken apart rather than demolished, so all the energy that went into making them isn't wasted. It may also be possible to substitute minerals from natural sources by other types of mineral wastes, such as the 76 million tonnes of waste arising from excavation and quarrying, 14 million tonnes of mineral wastes that come from other industries, or 4 billion tonnes of historical mining wastes. We can also be more frugal in our use of mineral-based construction materials, by designing materials, products and structures to use less primary raw materials, last longer, and be suitable for repurposing rather than demolition, and using new manufacturing techniques. First, our research will try to better understand how mineral-based construction materials flow through the economy, over all the stages of their life cycle, including extraction, processing, manufacture, and end-of-life. The Centre will work to support the National Materials Database planned by the Office of National Statistics, which will capture how, where and when materials are used and waste arises, so that we have the information to improve this system. We will also study how any changes we might make to practices around minerals use would affect the environment and the economy, such as greenhouse gas emissions, costs to businesses, or jobs. Second, we will work on technical improvements that we can make in design of mineral-based products and structures, and in all the life-cycle stages of mineral-based construction materials. Third, we will look at how changes in current business models and practices could support use of less mineral-based construction materials, such as how they might be able to move more quickly to new technologies, or how they might use digital technologies to keep track of materials. We will explore how the government can support these changes, and how we can provide education so that everyone working in this system understands what they need to do. In the first 4 years of our Centre, 15 postdoctoral researchers will gain research experience working in the universities for 2y and will then work with an industrial collaborator for a year, to implement the results of their research. More than 20 PhD and 30 MSc students will also be trained in the Centre.