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This study investigates the potential for Electrical Resistivity Tomography (ERT) to detect buried glass ‘hotspots’ in a glass waste dump based on results from an open glass dump investigated initially. This detection potential is vital for excavation and later use of buried materials as secondary resources. After ERT, test pits (TPs) were excavated around suspected glass hotspots and physico-chemical characterisation of the materials was done. Hotspots were successfully identified as regions of high resistivity (>8000 Ωm) and were thus confirmed by TPs which indicated mean glass composition of 87.2% among samples (up to 99% in some). However, high discrepancies in material resistivities increased the risk for introduction of artefacts, thus increasing the degree of uncertainty with depth, whereas similarities in resistivity between granite bedrock and crystal glass presented data misinterpretation risks. Nevertheless, suitable survey design, careful field procedures and caution exercised by basing data interpretations primarily on TP excavation observations generated good results particularly for near-surface materials, which is useful since glass waste dumps are inherently shallow. Thus, ERT could be a useful technique for obtaining more homogeneous excavated glass and other materials for use as secondary resources in metal extraction and other waste recycling techniques while eliminating complicated and often costly waste sorting needs.

Around former glass factories in south eastern Sweden, there are dozens of dumps whose radioactivity and physico-chemical properties were not investigated previously. Thus, radiometric and physico-chemical characteristics of waste at Madesjö glass dump were studied to evaluate pre-recycling storage requirements and potential radiological and environmental risks. The material was sieved, hand-sorted, leached and scanned with X-Ray Fluorescence (XRF). External dose rates and activity concentrations of Naturally Occurring Radioactive Materials from 238U, 232Th series and 40K were also measured coupled with a radiological risk assessment. Results showed that the waste was 95% glass and dominated by fine fractions (< 11.3 mm) at 43.6%. The fine fraction had pH 7.8, 2.6% moisture content, 123 mg kg-1 Total Dissolved Solids, 37.2 mg kg-1 Dissolved Organic Carbon and 10.5 mg kg-1 fluorides. Compared with Swedish EPA guidelines, the elements As, Cd, Pb and Zn were in hazardous concentrations while Pb leached more than the limits for inert and non-hazardous wastes. With 40K activity concentration up to 3000 Bq kg-1, enhanced external dose rates of 40K were established (0.20 mSv h-1) although no radiological risk was found since both External Hazard Index (Hex) and Gamma Index (Iγ) were < 1. The glass dump needs remediation and storage of the waste materials under a safe hazardous waste class ‘Bank Account’ storage cell as a secondary resource for potential future recycling.

Physico-chemical characteristics of waste, particularly fine fraction (FF), from an old crystal glass waste dump in Sweden were studied to assess recycling or disposal alternatives. Hand-sorting of the waste indicated glass content of 44.1% while sieving established the FF as a more soil-like mix of glass and other materials constituting 33.3% of all excavated waste. The FF was around neutral pH with 24.4% moisture content, low values of Total Dissolved Solids, Dissolved Organic Carbon and fluorides, but hazardous concentrations of As, Cd, Pb and Zn according to the Swedish Environmental Protection Agency guidelines. While the FF leached metals in low concentrations at neutral pH, it leached considerably during digestion with nitric acid, implying leaching risks at low pH. Thus, the waste requires safe storage in hazardous waste class ‘bank account’ storage cells to avoid environmental contamination as metal recovery and other recycling strategies for the glass waste are being developed. The study could fill the information gap regarding preservation of potential resources in the on-going, fast-paced excavation and re-landfilling of heavy metal contaminated materials in the region.

Risks associated with metal contaminated sites are tightly linked to material leachability and contaminant mobility. In this study, metal solubility and transport were characterized within a glass waste landfill through i) lysimeter-collection of pore water and standardized batch leaching tests, ii) soil profiles extending from the landfill surface, through unsaturated soil underneath, and into the groundwater zone, and iii) groundwater samples upstream, at, and downstream of the landfill. The soil analyzes targeted both pseudo-total and geochemically active concentrations of contaminant metals (As, Cd, Pb, Sb) and basic soil geochemistry (pH, org. C, Fe,Mn). Water samples were analyzed for dissolved, colloid-bound and particulate metals, and speciation modelling of the aqueous phase was conducted. The results revealed a highly contaminated system, with mean metal concentrationsin the waste zone between 90 and 250 times the regional background levels. Despite severe contamination of the waste zone and high geochemically active fractions (80–100%) of all contaminant metals as well as elevated concentrations in landfill pore water, the concentrations of Cd and Pb decrease abruptly at the transition between landfill and underlying natural soil and no indication of groundwater contamination was found. The efficient cation retention is likely due to the high pH. However, the sorption of As and Sb is weaker at such high pH,which explains their higher mobility from the pore water zone into groundwater. The field soil:solution for Pb, ranging from 140 to 2,900,000 l kg−1), despite little variability in basic geochemical variables, which we suggest is due to waste material heterogeneity.

An old glass dumpsite in southern Sweden was mapped and investigated to locate glass abundance zones (“hotspots”) and understand physicochemical parametres of the waste. Global Positioning System (GPS) was used for mapping the site while a geophysical method of Electrical Resistivity was used for detecting glass hotspots in the dump. Test pits were excavated and samples taken, after which hand sorting, sieving and X-Ray Fluorescence (XRF) scanning of the waste were used for physicochemical properties. Geophysical mapping was found to be a feasible nondestructive tool in locating glass hotspots. In terms of composition, glass was found to be the most abundant fraction at 90% average from all 4 sampling points. From particle size distribution, particles > 11.3 mm were more abundant (75% average) than particles < 11.3 mm. XRF scanning yielded As, Cd and Pb concentrations of 3,700 mg/kg, 500 mg/kg and 5,300 mg/kg, respectively. In conclusion, it is possible to locate glass hotspots and excavate them carefully in readiness for metal extraction while avoiding the need for complicated sorting post-excavation.

Landfills and dumpsites have been the ultimate end of life sinks for various materials and products. As such, they are considered rich stocks of secondary raw materials for the circular economy. However, most of them are non-sanitary as they lack protective measures against environmental contamination. Over the years, the need to exploit the resource potential of landfills as well as to mitigate their contamination problems, among other factors, has led to the concept of landfill mining, resulting in a number of mainly pilot scale mining of landfills and dumps globally. In southeastern Sweden for instance, where there are over forty old, contaminated glass dumps, a number of remedial dumpsite excavations have been going on, with eventual landfilling of excavated materials in sanitary landfills. Hence, based on the Swedish situation, this study presents three scenarios about: contaminated materials in non-sanitary dumps as they currently stand; ongoing material excavations with subsequent landfilling; and material excavations coupled with materials recovery towards reduced landfilling. The third scenario is presented as more suitable from the circular economy perspective. The scenario is thus discussed in terms of technological implications of the process from identification of concealed valuable materials in dumps to their excavation, sorting, temporal storage, valorization and eventual resource recovery. In addition, legal implications as well as potential social, economic and environmental barriers against the scenario’s implementation are discussed. Finally, the study provides recommendations that would be useful in decision making surrounding the management of contaminated and non-sanitary dumpsites.

Waste physico-chemical characteristics and the presence and availability of three metals (As, Cu and Pb) in a glassworks dumpsite were investigated to assess excavated waste handling and storage requirements pre-valorisation. Eight 2 m deep test pits (TPs) were excavated and sampled at 0.5 m depth intervals. The excavated waste was hand-sorted, followed by X-Ray Fluorescence (XRF) scanning, leaching and HNO3 digestion of the fine fraction (< 10 mm), and assessing results against Swedish EPA regulations. The waste composition was glass > inert > organic > “other” waste, whereas the total metal concentrations (XRF) were Pb > As > Cu. Pb (all TPs) and As (four TPs) were in hazardous levels whereas Cu was not. TDS (2856 ± 467 mg kg-1) and DOC (56.4 ± 21.8 mg kg-1) were lower than the inert, non-hazardous and hazardous waste storage thresholds, whereas F- (10.8 ± 2 mg kg-1) was higher than the inert waste storage threshold. Moisture content was 24.4 ± 11.4% while pH was 7.3 ± 0.8. Leached metal concentrations were Pb > As > Cu, with low metal leachability (0.02% - 0.2%), and the leached amounts were lower than the non-hazardous and hazardous waste storage thresholds, but higher than the inert waste storage thresholds. HNO3 digestion yielded As and Cu concentrations higher than the thresholds for sensitive and less sensitive land uses, and Pb concentrations higher than the non-hazardous waste storage threshold. Metal recovery was 49.3%, 44.2% and 17.9% for Cu, Pb and As respectively. Although the waste was hazardous in nature based on total metal concentrations and Pb concentrations from acid digestion, the leaching was not in hazardous levels due to strongly bound metals in the waste material.

This study addresses the reactivity and risks of metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, Zn, As and Sb) at a Swedish site with large glass waste deposits. Old glassworks sites typically have high total metal concentrations, but as the metals are mainly bound within the glass waste and considered relatively inert, environmental investigations at these kinds of sites are limited. In this study, soil and landfill samples were subjected to a sequential chemical extraction procedure. Data from batch leaching tests and groundwater upstream and downstream of the waste deposits were also interpreted. The sequential extraction revealed that metals in <2 mm soil/waste samples were largely associated with geochemically active fractions, indicating that metals are released from pristine glass and subsequently largely retained in the surrounding soil and/or on secondary mineral coatings on fine glass particles. From the approximately 12,000 m(3) of coarse glass waste at the site, almost 4000 kg of Pb is estimated to have been lost through corrosion, which, however, corresponds to only a small portion of the total amount of Pb in the waste. Metal sorption within the waste deposits or in underlying soil layers is supported by fairly low metal concentrations in groundwater. However, elevated concentrations in downstream groundwater and in leachates of batch leaching tests were observed for several metals, indicating on-going leaching. Taken together, the high metal concentrations in geochemically active forms and the high amounts of as yet uncorroded metal-rich glass, indicate considerable risks to human health and the environment.

More than 34 old glasswork sites in the southeastern part of Sweden pose a permanent threat to human and environmental health due to the presence of toxic metals in open dumps with glass waste. The possibility of leaching of metals from different fractions of the disposed waste needed to be assessed. In the present investigation, leachate from fine fraction (soil plus glass particles < 2 mm) was characterized as following: pH (7.3), TOC (< 2%), organic content (4.4%), moisture content (9.7), COD (163 mg/kg) and trace elements content, being the values in accordance to the Swedish guidelines for landfilling of inert materials. However, very high metals content was found in the fine fraction as well as in all colors of the glass fraction (≥ 2 mm), whose values were compatible to hazardous waste landfill class. Tests with Lepidium sativum growing in the fine fraction as substrate revealed chronic toxicity expressed as inhibition of root biomass growth in 11 out of 15 samples. Additionally, leachate from fine fractions posed acute toxicity to genetically modified E. coli (Toxi-Chromotest). This study highlights the importance of combining physicochemical characterization with toxicity tests for both solid waste and leachate obtained from different waste fractions for proper hazardousness assessment supporting decision making on remediation demands.

More than 34 old glasswork sites in the southeastern part of Sweden pose a permanent threat to human and environmental health due to the presence of toxic metals in open dumps with glass waste. The possibility of leaching of metals from different fractions of the disposed waste needed to be assessed. In the present investigation, leachate from fine fraction (soil plus glass particles < 2 mm) was characterized as following: pH (7.3), TOC (< 2%), organic content (4.4%), moisture content (9.7), COD (163 mg/kg) and trace elements content, being the values in accordance to the Swedish guidelines for landfilling of inert materials. However, very high metals content was found in the fine fraction as well as in all colors of the glass fraction (≥ 2 mm), whose values were compatible to hazardous waste landfill class. Tests with Lepidium sativum growing in the fine fraction as substrate revealed chronic toxicity expressed as inhibition of root biomass growth in 11 out of 15 samples. Additionally, leachate from fine fractions posed acute toxicity to genetically modified E. coli (Toxi-Chromotest). This study highlights the importance of combining physicochemical characterization with toxicity tests for both solid waste and leachate obtained from different waste fractions for proper hazardousness assessment supporting decision making on remediation demands.