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Iron and steel slags have a long history of both disposal and beneficial use in the coastal zone. Despite the large volumes of slag deposited, comprehensive assessments of potential risks associated with metal(loid) leaching from iron and steel by-products are rare for coastal systems. This study provides a national-scale overview of the 14 known slag deposits in the coastal environment of Great Britain (those within 100 m of the mean high-water mark), comprising geochemical characterisation and leaching test data (using both low and high ionic strength waters) to assess potential leaching risks. The seaward facing length of slag deposits totalled at least 76 km, and are predominantly composed of blast furnace (iron-making) slags from the early to mid-20th Century. Some of these form tidal barriers and formal coastal defence structures, but larger deposits are associated with historical coastal disposal in many former areas of iron and steel production, notably the Cumbrian coast of England. Slag deposits are dominated by melilite phases (e.g. gehlenite), with evidence of secondary mineral formation (e.g. gypsum, calcite) indicative of weathering. Leaching tests typically show lower element (e.g. Ba, V, Cr, Fe) release under seawater leaching scenarios compared to deionised water, largely ascribable to the pH buffering provided by the former. Only Mn and Mo showed elevated leaching concentrations in seawater treatments, though at modest levels (<3 mg/L and 0.01 mg/L, respectively). No significant leaching of potentially ecotoxic elements such as Cr and V (mean leachate concentrations <0.006 mg/L for both) were apparent in seawater, which micro-X-Ray Absorption Near Edge Structure (μXANES) analysis show are both present in slags in low valence (and low toxicity) forms. Although there may be physical hazards posed by extensive erosion of deposits in high-energy coastlines, the data suggest seawater leaching of coastal iron and steel slags in the UK is likely to pose minimal environmental risk. [ABSTRACT FROM AUTHOR]

Lithification of artificial ground comprising by-products of legacy iron and steel workings presents a range of opportunities including atmospheric carbon dioxide (CO2) storage. The natural environmental processes altering these waste sites can also pose challenges such as ecotoxic metal leaching, and so it is important to characterise these largely undocumented anthropogenically-derived rocks. This study documents the lithification mechanisms, as well as mineralogical and geochemical characteristics across a legacy coastal iron and steel slag deposit (in Warton, England). X-Ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis of the slag deposit, as well as thermogravimetric analysis (TGA) of the cream-coloured material covering the deposit, shows lithification both on the top surface and the seaward side above the mean high-water mark (MHWM), which is the result of carbonate mineralisation. This process is driven by water weathering slag minerals (gehlenite, åkermanite, and pseudowollastonite), which release calcium (Ca). Ingassed and hydroxylated atmospheric CO2 reacts with the leached Ca to form calcite that is slightly to strongly depleted in 13C (δ13C values: -6.4 ‰ to -22.7 ‰), following partial dissolved inorganic carbonate (DIC) equilibrium. Calcium-silicate-hydrate (CSH) precipitation was responsible for lithifying the deposit where more frequent and abundant seawater washing prevents subsequent slag mineral dissolution and carbonate precipitation. This work shows that legacy iron and steel slag deposits are prone to lithification, particularly in coastal settings. This lithification can draw down atmospheric CO2 and has the potential to slow the release of toxic metals from CSH precipitation, enhancing the possibility for repurposing legacy industrial waste for CO2 storage and coastal defence applications.

The disposal of solid waste in dumpsites is getting increased in developing countries due to rapid urbanization. Biomining is an innovative idea to recover valuable resources from legacy waste and usable land from old dumpsites. Various mechanical equipments are employed in the biomining process, out of which the trommel screen plays a major role in sieving the legacy waste into different fractions. Optimization of trommel screen performance in the biomining process is carried out in this project. Feasible operating parameters such as the feed rate of the trommel screen 1 (100 mm) and trommel screen 2 (4 mm) and moisture content of legacy waste were optimized in the Rajapalayam biomining site, Tamil Nadu, India. The characteristics of legacy waste in three different biomining sites, namely, Rajapalayam, Srivilliputhur, and Sivakasi, were analyzed. Results indicate that 9 and 2 m3 h–1 feed rates show more separation efficiency for trommel 1 and 2, respectively. Changing the feed rates to the optimized values is also suggested to get better separating efficiency without compromising the purity and recovery of fractions. The recovery of the underflow fraction is maximum at a moisture content of 1.5% and 5.3% for trommel 1 and trommel 2, respectively. The trommel screen gets clogged for higher and lower values of moisture content so that the recovery of the underflow fraction gets affected. The refuse‐derived fuel (RDF) characteristics meet the standard for reuse in cement kilns, and the bioearth characteristics are not suitable to be used as a soil amendment in its original form due to the unavailability of nutrients such as NPK and elevated C/N ratio. [ABSTRACT FROM AUTHOR]

The legacy of the early days of the Atomic Age consists of many problematic sites worldwide, including radioactive waste dumps, uranium mines, spent fuel reprocessing plants, and defunct processing and enrichment plants. Although nature quickly reclaims abandoned sites, any remaining radioisotopes can pose a threat for millennia to come, long after the benefits gained from nuclear technology have faded. The field of nuclear industrial archaeology specialises in finding and characterising these sites to support local communities and site owners. Where maps and building plans have been lost, nuclear archaeologists deploy state-of-the-art analysis techniques on the ground to unravel the current state of legacy sites, and quantify the remaining radioactive inventories to the standard required by the nation the site is located within. The objectives of nuclear industrial archaeology are varied and site dependent. Whether the objective is to puzzle the forgotten history of activity back together or safeguard and recover dangerous radioactive materials, nuclear industrial archaeology adapts radioanalytical laboratory and site-surveying techniques in order to understand the site and allow scientists to communicate this information to support remediation efforts. This paper discusses current methodologies alongside a case study. [ABSTRACT FROM AUTHOR]

Landfill biomining (LFBM) has been proposed as a viable method for the reclamation of legacy waste dumpsites as well as the subsequent recovery of valuable resources and land value spaces. Despite these advantages, the potential of LFBM faces a significant challenge due to the composition, characteristics and end-use of the excavated materials. This paper assesses the composition of the excavated waste obtained during the LFBM operation of the four legacy waste heaps at the Boragaon dumpsite in North-East India and determines the physicochemical characteristics crucial for the material and energy recovery from the key reclaimed fractions. The compositional analysis revealed that the proportion of combustible and non-combustible fractions decreases from the youngest heap HP4 to the oldest heap HP1 due to variations in the consumption habits of the local community and the inadequate recycling of recyclable materials. However, the proportion of fine fraction (FF) shows an increasing trend from HP4 to HP1, suggesting enhanced biodegradation of easily degradable waste over the years. The proximate and energy content analysis suggest that refuse-derived fuel (RDF) preparation is the most suitable valorization option for the combustible fractions since surface defilements are too high for good quality material recovery. The elevated amount of organic matter and leachable heavy metals indicate that unrestricted reuse of FF as earth-fill material can cause long-term settlements and groundwater contamination, respectively. Even though every dumpsite is different in characteristics, the findings of this case study can assist in developing new strategies for recycling excavated waste. [ABSTRACT FROM AUTHOR]

Legacy waste dumpsites have been a significant environmental concern in India for many years. These dumpsites are characterized by the uncontrolled disposal of Municipal Solid Waste (MSW) and have led to various types of pollution and disease outbreaks. As India faces the challenges of rapid urbanization and increased waste generation and with over 3000 legacy waste dumpsites in the country, the need to address these legacy waste dumpsites has become paramount. As we continue to struggle extensively for waste management as well as space, landfill mining has been recognized as a promising way of recovering resources in our country by employing various technological and engineering advancements to extract valuable materials and energy from legacy waste streams. Unlike existing waste management approaches, this review explores the application of a novel Recovery Potential Index (RPI) for legacy waste dumpsites in India, which evaluates the feasibility of waste treatment facilities based on waste compositions and recovered material quantities. Depending on the RPI, recovered fine fractions can be sold as city compost or used as fill material, while recyclable, combustible, and inert fractions could be directed towards appropriate recycling or landfill uses. Unscientific and uncontrolled landfill mining practices could lead to unanticipated impacts on the nearby environment in the form of heavy contamination, thereby presenting this practice as a challenge in addition to the immense opportunities it provides. [Display omitted] • Legacy waste poses major environmental and health risks. • Effective planning is crucial for LFM to maximize resource recovery and viability. • RPI can aid in the targeted recovery of resources from legacy waste. • Research and infrastructure investment is key to overcome challenges. [ABSTRACT FROM AUTHOR]

• Effect of ageing on different physicochemical characteristics of the excavated waste. • Fine fraction (<4 mm) accounted highest ∼45%, while metal content was <1%. • Assessment for the valorisation of the recovered waste streams. This paper assesses the effect of ageing on physicochemical characteristics of excavated municipal solid waste from Mulund dumpsite in Mumbai, India. Based on disposal year, waste was excavated from different zones in the dumpsite. The excavated waste was screened into five different size categories and further sorted into different streams. Physicochemical characteristics, i.e., pH, bulk density, ultimate and proximate analysis, calorific value and heavy metal concentration of excavated waste were also determined. The results indicate a change in the characteristics and composition of waste with age. The particle size distribution of waste revealed that waste above 80 mm was mostly plastic and textile, whereas <4 mm (fine fraction) composed of soil-like material. Above 80 mm fraction shows a decreasing trend with age and depth, suggesting particle size reduction with time. Parameters like volatile matter, total and organic carbon and calorific value of excavated waste also reduced with the age. A significant portion of waste was fine fraction (∼45%) emphasising on its valorisation for success of landfill mining. Furthermore, metal content in the dumpsite was <1%. The findings from this study can be used to reclaim dumpsites and suggest possible valorisation routes for excavated waste in developing countries like India. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tanner diagram illustrates that MSW does not need auxiliary fuel for combustion. • Heating value of MSW and legacy waste were 37.74 and 40.43 MJ/kg, respectively. • High lignin content in MSW suggests char production suitability. • MSW has activation energy of 5.72 kJ/mol, less than legacy waste of 14.96 kJ/mol. • Legacy waste has lower energy barrier (5.42 kJ/mol) than MSW (113.86 kJ/mol). This study explores the viability of utilizing municipal solid waste (MSW) and legacy waste as a renewable energy source through pyrolysis, akin to solid fuels. The heating value of MSW and legacy waste were found to be 37737.89 and 40432.84 kJ/kg, respectively. Proximate analysis shows that MSW fits within Tanner diagram parameters, eliminating the need for auxiliary fuel in pyrolysis. With 47.6 % and 44.16 % lignin content in MSW and legacy waste were deemed suitable for char production. Thermal degradation resulted in mass losses of 68 % for MSW and 82 % for legacy waste. The kinetic and thermodynamic assessment indicates lower activation energy (E a) and Gibbs free energy (ΔG) for MSW (5.72 kJ/mol and 170.37 kJ/mol, respectively) compared to fossil fuels, suggesting faster reactions without additional energy requirement. MSW emerges as a promising alternative to fossil fuels, aligning with the United Nations' 2030 Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

The management of sediment and water contamination from legacy waste is a significant problem in Antarctica. Although several reports have noted that there are contaminated sites at the abandoned Wilkes Station, a systematic attempt to assess the spatial scale of the problem has not been made, making development of clean-up or preservation programmes difficult. A contaminated site assessment for the old Wilkes Station and surrounds is presented in this paper. The Australian and New Zealand Environment and Conservation Council (ANZECC) sediment and water quality guidelines and background concentration levels (BCL) were used to assess the extent of contamination across Clark Peninsula. Of 67 sediment sites sampled, 72% were contaminated with at least one metal or metalloid, with values exceeding the ANZECC ISQG-High or 2 x BCL. Moreover, 19% were contaminated with four or more metals/metalloids. Of the 93 water samples collected, all but one was contaminated with at least one metal/metalloid concentration exceeding the guidelines, and 96% were contaminated with two or more metals/metalloids. For hydrocarbons in sediment and water, most samples were below quantitation limits. There is a complex pattern of contamination across Clark Peninsula that needs to be considered in future waste treatment, containment or removal operations, and for protection of heritage items. [ABSTRACT FROM AUTHOR]

Beginning in 1943, process wastes containing approximately 1.85 × 1015 Bq (200 kg) of plutonium (Pu) were released into unlined cribs, trenches, and field tiles at the Hanford Site, Washington, USA. The 216-Z-9 (Z-9) unlined trench received over 4 × 106 L of mixed Pu processing waste from the Plutonium Finishing Plant (PFP) consisting of high ionic strength (∼ 5 M nitrate, ∼ 0.6 M aluminum), acidic (pH ∼ 2.5) solutions, which also contained the organic solvents: tributyl phosphate (TBP), dibutyl butylphosphonate (DBBP), carbon tetrachloride (CCl 4), and lard oil. A small fraction of Pu migrated deep into the subsurface vadose zone to depths of 37 m, but the mechanisms controlling Pu migration beneath the trench are unknown. In this study, we determined Pu partitioning behavior in a series of binary and ternary batch experiments containing aqueous, organic, and solid phases representative of the waste constituents and natural sediments of the Z-9 trench in order to develop a conceptual model for the transport of Pu in the subsurface. Our results show that Pu at equilibrium with low pH, high nitrate waste and in the presence of a TBP/organic phase can migrate as a Pu-TBP-nitrate complex in the organic phase as long as the low pH and high nitrate concentrations are maintained. Reducing the nitrate concentrations or increasing the pH will lead to Pu partitioning into the aqueous phase from the organic phase with subsequent sorption to native Hanford sediments. The results of this work suggest that Pu migration in the subsurface is likely driven by weak sorption of aqueous Pu under low pH conditions as well as the formation of Pu-TBP-nitrate complexes in the organic phase. Long-term Pu migration will be limited by the transient nature of the low pH conditions and the dispersion of the nitrate plume. [Display omitted] • Pu at equilibrium with high nitrate acidic waste can migrate with the TBP organic phase. • Neutralization and dilution of the waste will lead to Pu partitioning into the aqueous phase. • Pu in the aqueous phase is available for sorption to native sediments. • Long-term Pu mobility will be limited by neutralization and dilution of the waste. [ABSTRACT FROM AUTHOR]

Old landfills and dumpsites, created due to a linear approach towards municipal solid waste (MSW) management, are one of the major environmental hazards, especially in developing countries. Around 50% of the dumped waste can be characterized as fine fraction (FF), making its recovery a vital parameter for achieving a circular economy. This study investigates the application of FF obtained from the Indian MSW dumpsite to replace topsoil used for fired brick production, which is one of the primary construction materials in India. The raw materials (FF and clay) were mixed in different proportions and fired at a temperature of 800–1000 °C. Physicochemical, mechanical and environmental properties were analyzed for fired bricks using standard methods. Results showed that the fired bricks produced from FF had low density and thermal conductivity than control bricks providing advantages over conventional bricks for transportation and energy savings. The compressive strength (CS) of the bricks increased with an increase in temperature and reduced with an increase in FF, suggesting only a certain amount of clay can be replaced. Hence further optimization using response surface modelling was carried out. The optimization results showed that clay could be substituted up to 23% at 1000 °C (CS = 37.5 N/mm2) by FF to meet Indian regulatory limits for CS. Toxicity characteristic leaching procedure test showed that fired bricks produced from FF are safe for application. The study shows that FF can substitute part of clay in fired brick production, which can help to curb topsoil exploitation while achieving a circular economy by bringing dumped FF back to the anthropogenic material cycle. [Display omitted] • Fine fraction recycling from dumpsite as construction material. • Thermal and mineralogical characterization of raw materials (fine fraction and clay). • Mechanical performance of fired bricks produced from fine fraction and clay. • Response surface modelling (RSM) for optimizing fine fraction utilization. • Environmental assessment for bricks manufactured from fine fraction. [ABSTRACT FROM AUTHOR]

Results of investigations into factors influencing contaminant mobility in a replica trench located adjacent to a legacy radioactive waste site are presented in this study. The trench was filled with nonhazardous iron- and organic matter (OM)-rich components, as well as three contaminant analogues strontium, cesium, and neodymium to examine contaminant behavior. Imposed redox/water-level oscillations, where oxygen-laden rainwater was added to the anoxic trench, resulted in marked biogeochemical changes including the removal of aqueous Fe(II) and circulation of dissolved carbon, along with shifts to microbial communities involved in cycling iron ( Gallionella , Sideroxydans ) and methane generation ( Methylomonas , Methylococcaceae ). Contaminant mobility depended upon element speciation and rainfall event intensity. Strontium remained mobile, being readily translocated under hydrological perturbations. Strong ion-exchange reactions and structural incorporation into double-layer clay minerals were likely responsible for greater retention of Cs, which, along with Sr, was unaffected by redox oscillations. Neodymium was initially immobilized within the anoxic trenches, due to either secondary mineral (phosphate) precipitation or via the chemisorption of organic- and carbonate-Nd complexes onto variably charged solid phases. Oxic rainwater intrusions altered Nd mobility via competing effects. Oxidation of Fe(II) led to partial retention of Nd within highly sorbing Fe(III)/OM phases, whereas pH decreases associated with rainwater influxes resulted in a release of adsorbed Nd to solution with both pH and OM presumed to be the key factors controlling Nd attenuation. Collectively, the behavior of simulated contaminants within this replica trench provided unique insights into trench water biogeochemistry and contaminant cycling in a redox oscillatory environment.