In this study, the ecotoxicological effects posed by bulk of the material obtained from landfill mining, that is, fine fraction (<10 mm), were assessed by performing bioassays tests with the aim of using the data in geoenvironmental applications, such as landfill biocover to control residual methane emissions from old landfills. Attention is mainly focused on the possible interaction of fine fractions with the test organism. The tested eluates of fine fraction exhibited low acute toxicity toward the bacteria Allivibrio fischeri and Escherichia coli, the marine rotifer Brachionus plicatilis, and brine shrimp Artemia salina. The eluates showed slight inhibitory effects on the germination of seeds of lettuce Lactuca sativa L. and timothy Phleum pratense L., and no inhibitory effects on germination of seeds of perennial ryegrass Lolium perenne L. The fine fraction studied in the present study can be characterized as acutely nontoxic or slightly acutely toxic. Correlation analysis revealed moderate positive correlation between lethality of rotifers and soluble content of organic compounds in the fine fraction eluates. In conclusion, the conducted experiments demonstrated that the usage of fine fraction for onsite applications such as landfill biocover may pose minimal environmental consequences, based on the ecotoxicity assessment. (C) 2022 American Society of Civil Engineers.

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.

Underground storage tanks used for auto oil spill waste contain many hazardous materials, including polycyclic aromatic hydrocarbons (PAHs) trace elements. These compounds pose a significant threat to the environment and affect negatively human health. The aim of this study was to characterize the soil of a former auto scrap yards in which oil spill tank leakage occurred in Sweden. The soil samples were collected from an area of 5 m² around an oil the tank which was highly contaminated with petroleum hydrocarbons (PHC) and trace elements (cobalt and lead). Another soil samples were collected from a nearby area that was not contaminated by PHC and they were considered as controls. The characterization of these soil samples was performed using two approaches. Analysis of the relevant physico-chemical soil properties included texture, organic matter, contaminant concentration and pH, while biological analyses were performed using three independent ecotoxicological tests with plant (Lepidium sativum), earthworm (Eisenia fetida) and soil microorganisms. Toxicity tests showed that contaminants had strongly negative effects on earthworm’s development and L. sativum shoots dry biomass in both PHC contaminated and control soils. These two parameters were the most sensitive in reflecting toxicity of study soils. Oxygen uptake rate (OUR) in aqueous phase was four times higher than that of the solid phase even though a similar trend was observed in both phases (aqueous and solid). Moreover, microorganism’s respiration was high in PHC contaminated soils in comparison to control soils due to the mineralization of readily available OM and/or organic pollutants as well as the inhibitory effect of TE on soil respiration. The results clearly demonstrated that combination of chemical analyses with three toxicity tests was appropriate to characterize mixed PHC and TE contaminated soils.

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.

Existing schemes of solid waste handling have been improved implementing advanced systems for recovery and reuse of various materials. Nowadays, the 'zero waste' concept is becoming more topical through the reduction of disposed waste. Recovery of metals, nutrients and other materials that can be returned to the material cycles still remain as a challenge for future. Landfill mining (LFM) is one of the approaches that can deal with former dumpsites, and derived materials may become important for circular economy within the concept 'beyond the zero waste'. Perspectives of material recovery can include recycling of critical industrial metals, including rare earth elements (REEs). The LFM projects performed in the Baltic Region along with a conventional source separation of iron-scrap, plastics etc. have shown that the potential of fine-grained fractions (including clay and colloidal matter) of excavated waste have considerably large amounts of potentially valuable metals and distinct REEs. In this paper analytical screening studies are discussed extending the understanding of element content in fine fraction of waste derived from excavated, separated and screened waste in a perspective of circular economy. Technological feasibility was evaluated by using modified sequential extraction technique where easy extractable amount of metals can be estimated. Results revealed that considerable concentrations of Mn (418-823 mg/kg), Ni (41-84 mg/kg), Co (10.7-19.3 mg/kg) and Cd (1.0-3.0 mg/kg) were detected in fine fraction (<10 mm) of waste sampled from Hogbytorp landfill, while Cr (49-518 mg/kg) and Pb (30-264 mg/kg) were found in fine fraction (<10 mm) of waste from Torma landfill revealing wide heterogeneity of tested samples. Waste should become a utilizable resource closing the loop of anthropogenic material cycle as the hidden potential of valuable materials in dumps is considerable. (C) 2018 Elsevier Ltd. All rights reserved.

A pilot scale experiment was conducted to investigate the aided-phytoextraction of metals and the aided-phytodegradation of petroleum hydrocarbons (PHC) in a co-contaminated soil. First, this soil was amended with compost (10% w/w) and assembled into piles (Unp-10%C). Then, a phyto-cap of Medicago sativa L. either in monoculture (MS-10%C) or co-cropped with Helianthus annuus L. as companion planting (MSHA-10%C) was sown on the topsoil. Physico-chemical parameters and contaminants in the soil and its leachates were measured at the beginning and the end of the first growth season (after five months). In parallel, residual soil ecotoxicity was assessed using the plant species Lepidium sativum L. and the earthworm Eisenia fetida Savigny, 1826, while the leachate ecotoxicity was assessed using Lemna minor L. After 5 months, PH C10-C40, PAH-L, PAH-M PAH-H, Pb and Cu concentrations in the MS-10%C soil were significantly reduced as compared to the Unp-10% C soil. Metal uptake by alfalfa was low but their translocation to shoots was high for Mn, Cr, Co and Zn (transfer factor (TF) >1), except for Cu and Pb. Alfalfa in monoculture reduced electrical conductivity, total organic C and Cu concentration in the leachate while pH and dissolved oxygen increased. Alfalfa co-planting with sunflower did not affect the extraction of inorganic contaminants from the soil, the PAH (M and H) degradation and was less efficient for PH C10-C40 and PAH-L as compared to alfalfa monoculture. The co-planting reduced shoot and root Pb concentrations. The residual soil ecotoxicity after 5 months showed a positive effect of co-planting on L. sativum shoot dry weight (DW) yield. However, high contaminant concentrations in soil and leachate still inhibited the L. sativum root DW yield, earthworm development, and L. minor growth rate. (C) 2017 Elsevier B.V. All rights reserved.

In common sense, a landfill is a place where the life cycle of products ends. Landfill mining (LFM) mostly deals with former dumpsites and derived material may have a significant importance for the circular economy. Deliverables of recently applied LFM projects in Sweden and Estonia have revealed the potential and problems for material recovery. There are 75-100 thousand old landfills and dumps in the Baltic Sea Region, and they pose environmental risks to soil, water and air by pollution released from leachate and greenhouse gas emissions. Excavation of landfills is potential solution for solving these problems, and at the same time, there are perspectives to recover valuable lands and materials, save expenses for final coverage of the landfills and aftercare control. The research project "Closing the Life Cycle of Landfills-Landfill Mining in the Baltic Sea Region for Future" included investigation at four case studies in Estonia and Sweden: Kudjape, Torma, Hogbytorp and Vika landfills. Added value of this research project is characterization of waste fine fraction material, determination of concentration for most critical and rare earth elements. The main results showed that both, coarse and fine, fractions of waste might have certain opportunities of recovery.

The fractionation of metals in the fine fraction (<10 mm) of excavated waste from an Estonian landfill was carried out to evaluate the metal (Pb and Cu) contents and their potential towards not only mobility but also possibilities of recovery/extraction. The fractionation followed the BCR (Community Bureau of Reference) sequential extraction, and the exchangeable (F1), reducible (F2), oxidizable (F3) and residual fractions were determined. The results showed that Pb was highly associated with the reducible (F2) and oxidizable (F3) fractions, suggesting the potential mobility of this metal mainly when in contact with oxygen, despite the low association with the exchangeable fraction (F1). Cu has also shown the potential for mobility when in contact with oxygen, since high associations with the oxidizable fraction (F3) were observed. On the other hand, the mobility of metals in excavated waste can be seen as beneficial considering the circular economy and recovery of such valuables back into the economy. To conclude, not only the total concentration of metals but also a better understanding of fractionation and in which form metals are bound is very important to bring information on how to manage the fine fraction from excavated waste both in terms of environmental impacts and also recovery of such valuables in the economy.

Landfill mining is an alternative technology that merges the ideas of material recycling and sustainable waste management. This paper reports a case study to estimate the value of landfilled materials and their respective market opportunities, based on a full-scale landfill mining project in Estonia. During the project, a dump site (Kudjape, Estonia) was excavated with the main objectives of extracting soil-like final cover material with the function of methane degradation. In total, about 57,777 m(3) of waste was processed, particularly the uppermost 10-year layer of waste. Manual sorting was performed in four test pits to determine the detailed composition of wastes. 11,610 kg of waste was screened on site, resulting in fine (<40 mm) and coarse (>40 mm) fractions with the share of 54% and 46%, respectively. Some portion of the fine fraction was sieved further to obtain a very fine grained fraction of <10 mm and analyzed for its potential for metals recovery. The average chemical composition of the <10 mm soil-like fraction suggests that it offers opportunities for metal (Cr, Cu, Ni, Pb, and Zn) extraction and recovery. The findings from this study highlight the importance of implementing best available site-specific technologies for on-site separation up to 10 mm grain size, and the importance of developing and implementing innovative extraction methods for materials recovery from soil-like fractions.

Leaching of fine fraction (< 10 mm) obtained from landfill mining activities in an Estonian landfill was done. On-site excavation was carried out in four test pits (TP1, TP2, TP3, TP4) that were further divided in four layers (L (1), L (2), L (3), L (4)). Total chemical oxygen demand (CODt), dissolved chemical oxygen demand (CODd), total organic carbon (TOC), dissolved organic carbon (DOC) and metals (Zn, Cu, Pb and Cd) were analyzed. The results showed that approximately 70 % of CODt were in particulate/colloidal state. The TOC released ranged between 2326 and 3530-mg/kg dry matter for test pits suggesting spatial differences in the studied landfill. DOC ranged between 365-874 and 317-940 mg/kg for different test pits and sampling layers, respectively. Low average leaching rates of metals were observed (0.2-1.5 %). Pb had a significantly higher average leaching rate (1.0 %) compared to Zn (0.70 %) and Cu (0.35 %). The potential use of CODt as a surrogate indicator of TOC, DOC and Zn on the basis of high correlation coefficients was observed. To conclude, the implementation of adequate strategies to manage fine-grained fractions obtained from excavated waste relies on physico-chemical characterization of both the fine fractions itself and the leachate generated during storage and use.