Landfills represent a continuous environmental threat due to the emission of different greenhouse gases, which are mainly responsible for the climate changes, and the contaminated leachate that affects the surface and ground water recipients. The circular economy approach appeared as a useful solution to reduce the depletion of the Earth’s natural resources and the environmental risk effects by considering all of the lost resources like wastes including the landfills as potential secondary resources. It is well known that characterizing the composition of landfill waste is an essential step in specifying the recycling methods. In the current research the waste composition at one of the first EU regulations-compliant sanitary landfills (the Torma landfill in Estonia) was studied. The results showed that the fine fraction (<20 mm) represented 53% of the total excavated waste materials while the waste to energy fraction (plastics, woods etc.) was the highest within the coarse fraction (>20 mm). The present work emphasized that mining landfills can be a good solution either for extracting primary raw materials like metals, as a source for recovering energy, or for acquiring landfill space.

Mining landfills and open dumpsites is associated with (40-70% by mass) fine fraction of particle sizes less than 20 or 10 mm. Soil and trace elements of considerable concentrations typically dominate the composition of this fraction. In the present paper, a modified three steps sequential extraction procedure was used to fractionate Cu, Zn and Cr in the fine fraction of waste sampled from Högbytorp (Sweden) and Torma (Estonia) landfills. The results showed that the major concentrations of Cu (98.8 and 98.6 wt%) and Cr (98.5% and 98.4 wt %) in fines from Högbytorp and Torma landfills, respectively. These data were found associated to the residual fraction. Noticeable concentrations of Cu and Cr were also found associated within the water -soluble fraction, which could be regarded as a potential risk. The Zn displayed different behavior by distributing in all the sequential extraction fractions in the fine fractions from the two landfills. Specifying the metals content using this method is essential to explore the valorization as well as the potential environmental risks by these fines fractions.

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.

At the southeastern part of Sweden, old art and crystal waste glass has been identified as a hazardous waste due to high weight concentrations of Pb (32.398%), Cd (0.085%) and As (1.976%). The reduction-melting technique was used to investigate the extraction of these trace elements from powder waste glass of particle size <1 mm. Following a factorial design technique, the experimental results of the reduction-melting method showed that 99.9% of Pb, 100% of Cd and 99% of As could be extracted. For a batch of 10 g powder waste glass, the found experimental and theoretical optimum operating conditions were 1100 ^oC of melting temperature, 5 g of Na₂CO₃, 2 g of carbon and 120 min of melting time. The reduction-melting method displayed promising results which might help in recycling the extracted trace elements and glass compared to the current used solution of landfilling as hazardous wastes.