19th century London dust-yards: A case study in closed-loop resource efficiency

The material recovery methods used by dust-yards in early 19th century London, England and the conditions that led to their development, success and decline are reported. The overall system developed in response to the market value of constituents of municipal waste, and particularly the high coal ash content of household ‘dust’. The emergence of lucrative markets for ‘soil’ and ‘breeze’ products encouraged dust-contractors to recover effectively 100% of the residual wastes remaining after readily saleable items and materials had been removed by the thriving informal sector. Contracting dust collection to the private sector allowed parishes to keep the streets relatively clean, without the need to develop institutional capacity, and for a period this also generated useful income. The dust-yard system is, therefore, an early example of organised, municipal-wide solid waste management, and also of public–private sector participation. The dust-yard system had been working successfully for more than 50 years before the Public Health Acts of 1848 and 1875, and was thus important in facilitating a relatively smooth transition to an institutionalised, municipally-run solid waste management system in England. The dust-yards can be seen as early precursors of modern materials recycling facilities (MRFs) and mechanical–biological treatment (MBT) plants; however, it must be emphasised that dust-yards operated without any of the environmental and occupational health considerations that are indispensable today. In addition, there are analogies between dust-yards and informal sector recycling systems currently operating in many developing countries

Global Review on Safer End of Engineered Life

In this Global Review on Safer End of Engineered Life, we take a long overdue and systematic look at the scientific evidence around waste and resources management and the impact on human health and life. Surprisingly, this research appears to be the first of its kind anywhere in the world. We offer suggestions for immediate corrective action that should be taken and identify where engineering solutions could mitigate and prevent harm to human life and health. We also suggest where further research is required into the nature and magnitude of the problem

Establishing a sub-sampling plan for waste-derived solid recovered fuels (SRF): Effects of shredding on representative sample preparation based on theory of sampling (ToS)

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 the art equipment, theoretical calculations by the theory of sampling (ToS) and implementation of best sub-sampling practices. Solid recovered fuel (SRF) was selected as a case of a solid waste sample with intermediate heterogeneity and chlorine (Cl) as an analyte with intermediate variability amongst waste properties. ToS nomographs were constructed for different sample preparation scenarios presenting the trend of uncertainty during sub-sampling. Nomographs showed that primary shredding (final d90 ≤ 0.4 cm) can reduce the uncertainty 11 times compared to an unshredded final sub-sample (d ≈ 3 cm), whereas cryogenic shredding in the final sub-sample can decrease the uncertainty more than three times compared to primary shredding (final d90 ≤ 0.015 cm). Practices that can introduce bias during sub-sampling, such as mass loss, moisture loss and insufficient Cl recovery were negligible. Experimental results indicated a substantial possibility to obtain a representative final sub-sample (uncertainty ≤ 15%) with the established sub-sampling plan (57–93%, with 95% confidence), although this possibility can be considerably improved by drawing two final sub-samples instead (91–98%, with 95% confidence). The applicability of ToS formula in waste-derived materials has to be investigated: theoretical ToS calculations assume a poorer performance of the sub-sampling plan than evidenced by the experimental results

Enabling the informal recycling sector to prevent plastic pollution and deliver an inclusive circular economy

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 wider risk perspective. Interventions should target three aspects of the pollution: reducing barriers to collection, improving the revenue from the materials and wider informal recycler remuneration, and increasing the quality of the materials. Done well, these interventions will increase the collection rate, reduce pollution from plastics, and help millions of people escape poverty. They present a scalable international solution to a global challenge; and are likely the only viable solution to the widespread lack of solid waste services and infrastructure across low- and middle-income countries

Chlorine in waste-derived solid recovered fuel (SRF), co-combusted in cement kilns: A systematic review of sources, reactions, fate and implications

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 mean Cl content in average commercially manufactured SRF is at 0.76 w/wd (± 0.14% w/wd, 95% confidence). Cl is widely dispersed amongst various chemical compounds present in several waste items—not just PVC. The variability around mean Cl in SRF is at 36.7% (CV), notably lower than that in MSW, indicating effective variability reduction because of mechanical processing of MSW into SRF. During co-combustion, most Cl remains within the kiln system causing operating problems and only a small percentage (0.7–13%) is incorporated in the clinker, making it stickier. A significant proportion is captured by the air pollution control system. State of the art engineering practices can result in suitable SRF quality assurance, largely preventing Cl-related problems in the kiln. Further investigation on the impact of fuel feeding systems, on effect of Cl speciation and on controlling the sources of Cl variability are needed to improve confidence in SRF uptake

Statistical quantification of sub-sampling representativeness and uncertainty for waste-derived solid recovered fuel (SRF): Comparison with theory of sampling (ToS)

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 recovered fuel (SRF) - an example of an inherently heterogeneous mixture containing hazardous properties. We used statistically designed experiments (DoE) (nested balanced ANOVA) to quantify uncertainty arising from material properties, sub-sampling plan and analysis. This was compared with the theoretically estimated uncertainty via theory of sampling (ToS). The sub-sampling scheme derives representative analytical results for relatively uniformly dispersed properties (moisture, ash, and calorific content: RSD ≤ 6.1 %). Much higher uncertainty was recorded for the less uniformly dispersed chlorine (Cl) (RSD: 18.2 %), but not considerably affecting SRF classification. The ToS formula overestimates the uncertainty from sub-sampling stages without shredding, possibly due to considering uncertainty being proportional to the cube of particle size (FE ∝ d3), which may not always apply e.g. for flat waste fragments. The relative contribution of sub-sampling stages to the overall uncertainty differs by property, contrary to what ToS stipulates. Therefore, the ToS approach needs adaptation for quantitative application in sub-sampling of waste-derived materials

Resource recovery and low carbon transitions: The hidden impacts of substituting cement with imported ‘waste’ materials from coal and steel production

Here we investigate the increasingly complex relationship between the resource recovery practices of the UK concrete industryandongoing low-carbontransitions takingplaceinelectricityandsteel.ReductionsinUKcoalbased electricity and primary steel production are reducing domestic availability of residues – coal ash and steel slag – that are used to replace cement in concrete; for decarbonisation purposes and to increase concrete quality. This is leading to an unusual mass-transportation of ‘wastes’ from the Global South to Global North. Focusing closely upon the mitigation pathways of concrete producers, we develop an inter-industry model of material flows, and a diversity of scenarios and sensitivity tests, to consider how resource recovery practices and carbon emissions of the three sectors may evolve. A continuation of domestic shortages in waste-derived cement substitutes appears inevitable and future international shortages possible. But even if foreign producers supplied enough cement substitutes to meet UK demand, the broader carbon implications of such trade may be far from benign. Using a revenue-based approach to allocate emissions to coal ash leads to a wide range of embodied carbon estimates – from relatively low (0.15t.CO2/t.ash) to exceeding that of traditional Portland cement (1t.CO2/t.ash). However, the carbonassociated withinternationally traded recovered resources currently stands behinda‘double-blind’systemofaccounting: emissionsdonotregisterintheconventionalterritorialaccountsof theimportingcountry andtheymaybehiddenfromitsconsumption-based accountsaswell.Theimpactsofsuch trade and related carbon accounting conventions are unclear and we emphasise the need for further investigation. To this end, our results demonstrate the importance of incorporating highly interconnected sectors and international trade into analyses of low-carbon transitions, and highlight the challenges this presents for designing appropriate policies, accounting frameworks, and interdisciplinary impact assessment methods that look beyond sectorial and national horizons.The UK Natural Environment Research Council (NERC), UK Economic and Social Research Council (ESRC) and Department for Environment, Food & Rural Affairs (DEFRA