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Geophysical investigation of glass ‘hotspots’ in glass dumps as potential
<br />secondary raw material sources
<br />Richard Nasilele Mutafela
<br />a,⇑, Etzar Gomez Lopez
<br />b, Torleif Dahlin
<br />b, Fabio Kaczala
<br />c, Marcia Marques
<br />a,d,
<br />Yahya Jani
<br />a, William Hogland
<br />a
<br />a Department of Biology & Environmental Science, Faculty of Health and Life Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden
<br />b Division of Engineering Geology, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
<br />c Sweco Environment AB, SE-392 35 Kalmar, Sweden
<br />d Department of Sanitary and Environmental Engineering, Rio de Janeiro State University UERJ, R. São Francisco Xavier, 524, CEP 20551-013, Rio de Janeiro, Brazil
<br />article info
<br />Article history:
<br />Received 8 July 2019
<br />Revised 31 January 2020
<br />Accepted 18 March 2020
<br />Keywords:
<br />Electrical resistivity tomography
<br />Secondary resources
<br />Glass waste
<br />Landfill mining
<br />Waste characterisation
<br />Circular economy
<br />abstract
<br />This study investigates the potential for Electrical Resistivity Tomography (ERT) to detect buried glass
<br />‘hotspots’ in a glass waste dump based on results from an open glass dump investigated initially. This
<br />detection potential is vital for excavation and later use of buried materials as secondary resources.
<br />After ERT, test pits (TPs) were excavated around suspected glass hotspots and physico-chemical charac-
<br />terisation of the materials was done. Hotspots were successfully identified as regions of high resistivity
<br />(>8000 Xm) and were thus confirmed by TPs which indicated mean glass composition of 87.2% among
<br />samples (up to 99% in some). However, high discrepancies in material resistivities increased the risk
<br />for introduction of artefacts, thus increasing the degree of uncertainty with depth, whereas similarities
<br />in resistivity between granite bedrock and crystal glass presented data misinterpretation risks.
<br />Nevertheless, suitable survey design, careful field procedures and caution exercised by basing data inter-
<br />pretations primarily on TP excavation observations generated good results particularly for near-surface
<br />materials, which is useful since glass waste dumps are inherently shallow. Thus, ERT could be a useful
<br />technique for obtaining more homogeneous excavated glass and other materials for use as secondary
<br />resources in metal extraction and other waste recycling techniques while eliminating complicated and
<br />often costly waste sorting needs.
<br />2020 The Authors. Published by Elsevier Ltd. ThisisanopenaccessarticleundertheCCBY-NC-NDlicense
<br />(http://creativecommons.org/licenses/by-nc-nd/4.0/).
<br />1. Introduction
<br />The world population has been increasing together with
<br />resource consumption and waste generation, resulting in negative
<br />environmental impacts. It is projected to further increase to 9.8 bil-
<br />lion by 2050, which is expected to triple the current resource
<br />demand to 140 billion tonnes of minerals, ores, fossil fuels and bio-
<br />mass per year (UN, 2017; UNEP, 2011). Decoupling of the economic
<br />growth rate from this high rate of natural resource consumption is
<br />thus recommended. In case of metals production, decrease in ore
<br />grades and stocks have been reported due to the need to meet
<br />the global demand (UNEP, 2013). Some trace elements such as
<br />Sb, As, Cd and Pb have been identified as high supply risk due to
<br />their low recycling rates, limited number of substitutes and being
<br />almost exclusively mined as by-product metals (British Geological
<br />Survey, 2015). The growing calls for secondary raw materials and
<br />reduced mining will further drop the supply of such elements.
<br />Therefore, alternative and sustainable sources are required.
<br />Around former glass factories in south-eastern Sweden, glass
<br />dumps are highly contaminated with As, Cd, Pb and Sb, with an
<br />estimation of 420,000 m
<br />3 of contaminated materials (420 tonnes
<br />of As, 30 tons of Cd and 3100 tons of Pb) in 22 dumps (Höglund
<br />et al., 2007). These materials pose contamination risks to humans
<br />and the environment (Augustsson et al., 2016), hence they have
<br />been recommended for remediation (Hogland et al., 2010). Alster-
<br />fors glass waste dump (current study site), for example, has an
<br />infiltration rate to groundwater of about 1200 m
<br />3 per year and
<br />combined As, B, Cd, Pb and Sb leakages to the Alsterån River at
<br />more than 20 kg per year (Höglund et al., 2007). These materials,
<br />on the other hand, could potentially contribute as secondary
<br />sources of some of the high supply risk metals. High contamination
<br />of excavated wastes is one of the main obstacles to their recycling
<br />as secondary raw materials (Hull et al., 2005), resulting in
<br />https://doi.org/10.1016/j.wasman.2020.03.027
<br />0956-053X/2020 The Authors. Published by Elsevier Ltd.
<br />This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
<br />⇑Corresponding author at: Department of Biology & Environmental Science,
<br />Faculty of Health and Life Sciences, Linnaeus University, Stuvaregatan 2, SE-392 31
<br />Kalmar, Sweden.
<br />E-mail address:richardnasilele.mutafela@lnu.se (R.N. Mutafela).
<br />Waste Management 106 (2020) 213–225
<br />Contents lists available at ScienceDirect
<br />Waste Management
<br />journal homepage: www.elsevier.com/locate/wasman
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