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The Landfill mining was introduced in research in Sweden for more than three and a half decades ago. During recent years, the focus has been on the glass dumps in the Kingdom of Crystal in southeastern Sweden. Mapping of the dumps, test pit excavations, sieving and sorting of the glass masses, characterization, laboratory extraction of the metals in the glass was performed as well as measurements of radioactivity done. The polluted soil underneath the removed glass masses was treated by remediation. At one of places at the Kingdom of Crystal a phytoremediation/tourist park was established in Orrefors including a summer glasswork for tourist activities.

The historical contamination of Smålands glass industry by hazardous concentrations of different trace elements (such as Pb, As, Zn, Cd and others) is a fact that has been approved by many researchers. These studies covered the situation of the glassworks contamination from different angles. However, the recommended solution by the Swedish Environmental Protection Agency is landfilling. Dumping these masses means, on the first hand, losing huge amounts of the Earth natural resources as wastes and, on the second hand, losing any future opportunity of recycling or reusing due to mixing these masses with other hazardous wastes generated by different sectors. In this paper, we are trying to review and highlight the results obtained by some of the already published studies in this field to identify the gap and challenges of recycling or reusing options.

Dredging activities are necessary to maintain the navigation depth of harbors and channels. Additionally,dredging can prevent the loss of water bodies. A large amount of extracted sediments is produced around theworld. Removed material is widely disposed at open seas or landfills. Much of the dredged material is pollutedand is classified as unsuitable for open-sea disposal. In Sweden, many dredging activities are taking placenowadays like that in Oskarshamn harbor, Inre harbor Norrköping municipality and Malmfjärden bay inKalmar. In this review, the potential of phytoremediation as a treatment method is discussed with focus onsuggested methods for reusing the treated sediments. Recycling or reusing of dredged and treated sedimentswill preserve Earth natural resources as well as reduce diffusion of contaminants to the environment.

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.

The ‘Glasriket’ of Sweden’s Småland region is characterized by an array of landfillsand dumpsites of glass and other raw material wastes from old glassworks. Most ofthe dumpsites contain heavy metals with leaching capabilities to soil and groundwater. As these metals could be potential resources that could be recovered into theresource loop, the characterization of these wastes can provide necessary informationabout the resource recovery potential. The current investigation focuses on the firststages by quantifying the amounts of selected metals (Ba, Cr and Zn) in the glassdeposit at Madesjö dumpsite as a case. The dump was sampled at nine different pointsand two levels per point. The samples were subjected to X-ray Fluorescence scanning(XRF) and leaching tests with further analyses of metals using ICP. According to theinvestigation, the highest metal contents in the solid phase were observed in Zn(average of 4515 mg/kg) while the lowest were observed in Cr (average of 72 mg/kg).In the liquid phase, the average metal concentrations were observed to be 0.37 mg/kg,0.02 mg/kg and 0.23 mg/kg for Ba, Cr and Zn respectively. These, however, are not inreadily available form, and so further investigations need to be done in order to findcost-effective techniques for their extraction. On the other hand, further investigationsneed to be done to ascertain the leaching potential by altering such leachingparameters as contact time and liquid to solid ratio.

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.

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.

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 (H_ex) and Gamma Index (I_γ) 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.

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.

Glass waste dumps from crystal glass production is an health issue due to the occurrence of antimony, arsenic, cadmium and lead in crystal glass. Recovery of those elements could both decrease pollution and recycle metals in the circular economy. Pyrometallurgy is a potential recovery method, yet limited by high energy consumption. Here we tested a lower-energy alternative in which glass is mechanically activated in a ball mill and leached with nitric acid. Results show that mechanical activation destabilised the glass structure and resulted in 78% lead extraction during leaching at 95 °C. Temperature had the most signifcant efect on extraction, whereas acid concentration, from 0.5 to 3 M, and leaching time, from 0.5 to 12 h, had insignifcant efects. In each experiment, 75% of the fnal extracted amount was achieved within 30 min. The study demonstrates potential for lead extraction from glass waste at lower acid concentration, shorter leaching time and lower temperature, of 95 °C, than traditional pyrometallurgical extraction, typically operating at 1100 °C.

Extraction of hazardous metals from dumped crystal glass waste was investigated for site decontamination and resource recovery. Mechanically activated glass waste was leached with biodegradable chelating agents of ethylenediamine-N,N'-disuccinic acid (EDDS) and nitrilotriacetic acid (NTA), where the concentration and reaction time were determined by using Box-Wilson experimental design. Hazardous metals of lead (Pb), arsenic (As), antimony (Sb) and cadmium (Cd) with concentrations higher than regulatory limits were extracted wherein the extraction yield was found to vary Pb > Sb > As > Cd. Extraction was influenced more by type and concentration of chelator rather than by reaction time. A maximum of 64% of Pb could be extracted by EDDS while 42% using NTA. It is found that increase of chelator concentrations from 0.05 M to 1 M did not show improved metal extraction and the extraction improved with reaction time until 13 h. This study provides sustainable alternative for treating hazardous glass waste by mechanical activation followed by extraction using biodegradable chelator, instead of acid leaching.