Waste Management 60 (2017) 596–600
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Penicillium expansum Link strain for a biometallurgical method to recover REEs from WEEE Simone Di Piazza a, Grazia Cecchi a,⇑, Anna Maria Cardinale b, Cristina Carbone c, Mauro Giorgio Mariotti a,b,c, Marco Giovine c, Mirca Zotti a a b c
Laboratorio di Micologia – Dipartimento di Scienze della Terra dell’Ambiente e della Vita, Università di Genova, Corso Europa 26, 16132 Genova, Italy Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genova, Italy Dipartimento di Scienze della Terra dell’Ambiente e della Vita, Università di Genova, Corso Europa 26, 16132 Genova, Italy
a r t i c l e
i n f o
Article history: Received 2 May 2016 Revised 18 July 2016 Accepted 23 July 2016 Available online 9 August 2016 Keywords: Urban mines Electronic waste Fungi Lanthanides bioaccumulation Mycometallurgy
a b s t r a c t Due to the wide range of applications in high-tech solutions, Rare Earth Elements (REEs) have become object of great interest. In the last years several studies regarding technologies for REE extraction from secondary resources have been carried out. In particular biotechnologies, which use tolerant and accumulator microorganisms to recover and recycle precious metals, are replacing traditional methods. This paper describes an original biometallurgical method to recover REEs from waste electrical and electronic equipment (WEEE) by using a strain of Penicillium expansum Link isolated from an ecotoxic metal contaminated site. The resulting product is a high concentrated solution of Lanthanum (up to 390 ppm) and Terbium (up to 1520 ppm) obtained from WEEE. Under this perspective, the proposed protocol can be considered a method of recycling exploiting biometallurgy. Finally, the process is the subject of the Italian patent application n. 102015000041404 submitted by the University of Genoa. Ó 2016 Elsevier Ltd. All rights reserved.
1. Introduction In the last decade the precious metals belonging to the platinum group and rare earths are playing a major role for both their high supply risks and environmental issues related to the End-ofLife products containing them (Binnemans et al., 2013). Moreover, Europe is not a primary producer of these materials, which are mainly imported from South Africa (precious metals) and China (Chi et al., 2011). Worldwide production forecast of Rare Earth Elements (REEs) esteemed 20–50 million tons/year (Wang and Xu, 2014). REEs are found in a huge swath of technologies, including smartphones, electronics, light bulbs, catalysts, glasses, medical devices, and other clean technologies that lead to a steep increase in their demand (Ongondo et al., 2011). However, today more than 95% of all REE production is in China, where low labor costs and lax regulations make it difficult for other countries to compete (Chi et al., 2011). Currently, China is stockpiling the metals in anticipation of future low production output. Facing possible scarcities of natural resources, among the different options, the recycle of REEs (from ⇑ Corresponding author. E-mail address:
[email protected] (G. Cecchi). http://dx.doi.org/10.1016/j.wasman.2016.07.029 0956-053X/Ó 2016 Elsevier Ltd. All rights reserved.
pre-consumers and post consumer-origins) is the only way to combine the demands of a growing market with the transition to a green – low carbon economy. Every year all over the world, huge amounts of raw materials are considered as waste, the so-called urban mines. In this context, the recovery of REEs from waste electrical and electronic equipment (WEEE) has a significant impact for different issues: economic, environmental, and social, as it has been estimated that the reuse of waste as raw materials (circular economy) could create, by 2020, 860,000 new jobs while reducing the greenhouse gas production of 415 Mt (U.S. Geological Survey, 2011). As for the recovery of metals from WEEE, the techniques currently considered are based on hydrometallurgical, pyrometallurgical, and biometallurgical processes (Shen & Forssberg, 2003; Cui and Zhang, 2008; Das, 2010). The related technologies are treated in more detail in Section 1.1. Our research regards a procedure that can be framed in the field of biometallurgy. The latter is a term used to describe biotechnological processes that involve interactions between microorganisms and metals or metal-bearing minerals (Gahan et al., 2013; Hennebel et al., 2015). Studies have been published addressing the interactions between microorganisms and REEs, including both REE mobilization from solids, through metabolic reactions, and REE
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immobilization from liquids, mainly through sorption by biomass (Ozaki et al., 2006). Concerning metals bioaccumulation techniques, Qu and Lian (2013) showed the advantages deriving from the employment of heterotrophic microorganisms, such as filamentous fungi. Fungi are able to develop metal tolerance and resistance mechanisms, such as metallothionein or phytochelatin proteins, which may bind and deactivate toxic metals, or enable the heavy metal storage in vacuoles (Gadd, 2007; Onofri et al., 2011). The first study that showed the metals, REEs, and lanthanides uptake capability by fungi was carried out by Aruguete et al. (1998). Some fungi may survive in contaminated environments, showing a very remarkable capability of contaminant inactivation and bioaccumulation (Ceci et al., 2012; Zotti et al., 2014; Roccotiello et al., 2015). More specifically Brandl et al. (2001) tested the Aspergillus niger Tiegh. and Penicillium simplicissimum (Oudem.) Thom capability to mobilize metals growing in the presence of electronic scraps. In Tsuruta (2007) tested the potential uptake capability of many microbial organisms (bacteria, actinomycetes, yeasts, and filamentous fungi) from media enriched with only one kind of REEs and a mixture of five REEs. Tsuruta also showed that it is possible to bioaccumulate and bioseparate REEs. D’Aquino et al. (2009) showed that Trichoderma species grew on REE enriched media. Dudeney and Sbai (1993) and Amin et al. (2014) discussed the accumulation of REEs from natural minerals, Zotti et al. (2014) from mine waste materials, and Qu and Lian (2013) from red mud. Another work demonstrates the sorption of REEs (dysprosium in this case) by the fungal strain Penidiella sp. T9 (Horiike and Yamashita, 2015). The capability of fungi to accumulate metals boosts the use of these organisms in biometallurgy and, especially, in the uptake or recovery of precious metals and REEs (Aruguete et al., 1998; Pethkar et al., 2001; Das, 2010). The branch of biometallurgic technology which exploits fungi to recover and extract metals is here in after defined with the neologism ‘‘mycometallurgy”. In view of the above, this work aims at setting up a novel and sustainable method to mycometallurgically recover REEs from WEEE. The paper deals with an innovative procedure to recover REEs from WEEE exploiting a strain of P. expansum isolated from a metal contaminated site. Although it is proven the fungi capability to accumulate metals, this capability is not completely exploited: our study proposes an integrated protocol on how to accumulate REEs by means of fungi and on how to recover REEs from fungal biomass using acid digestion. The resulting product is a high concentrated solution of REEs obtained from WEEE. Under this perspective, the proposed protocol can be considered a method of recycling exploiting mycometallurgy. 1.1. WEEE management aspects There are different methods for recovering metals from natural and not natural sources; some still being studied, others already ready as ‘‘packages” for industrial use. Usually, the recovery of metals from WEEE may be carried out through hydrometallurgical, pyrometallurgical, and biometallurgical techniques. Hydrometallurgical processes involve a strong acid attack of the WEEE previously prepared (crushing and possible demagnetization) to obtain an acid solution of dissolved metals (Rabatho et al., 2013; Lee et al., 2013). The process may be followed by an electrolytic reduction to obtain some metals in the elemental state or by a precipitation to obtain the salts of the metals. These techniques offer a very good yield, but require the use of a large volume of acid solutions; moreover, they are suitable only for recovery purposes and not for the purification of polluted sludges (Pant et al., 2012).
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Pyrometallurgic processes are based on the extraction of metals from the WEEE via alloying with other metals in the molten state (e.g. extraction of neodymium from permanent magnets Nd-Fe-B, through reaction with magnesium) (Takeda et al., 2006). These methods present good yields, but at the moment they may be used only for some elements. The main drawback is that the processes occur at (very) high temperatures. Biometallurgical techniques are based on biodissolution, bioabsorption, or bioaccumulation by means of bacteria or other organisms (Pant et al., 2012; Gahan et al., 2013). This technology is particularly suited for the recovery of metals from aqueous solutions or from low to medium concentrated solid materials: it may remove metals from diluted solutions and concentrate them to economically interesting concentrations (Beolchini et al., 2012; Lee and Dhar Pandey, 2012; Zhuang et al., 2015). To date in the field of environmental remediation the mainly exploited organisms are bacteria, which work in highly acidic environments to extract metals from contaminated sites (e.g. mining dumps) (Johnson, 2014). These processes result in an acid leachate, containing metals, which must undergo further treatments before being disposed of as waste. In comparison with conventional technologies, the biological approach is considered more cost efficient, simpler, and more environmentally friendly than their chemical counterparts (Beolchini et al., 2012). Moreover, biometallurgy is generally perceived as a much more environmentally benign (‘green’) approach. This technology, in fact, involves much lower temperatures (and hence energy costs) and the related processes operate at atmospheric pressure (Johnson, 2014). 2. Methods 2.1. Biological material and WEEE powder preparation The Penicillium expansum Link strain, used in our mycometallurgical experiments, was isolated from a colloidal precipitate, flowing from the contaminated mine site described in Carbone et al. (2014). The isolation was performed by following the modified dilution plate method discussed in Zotti et al. (2014). The latter allows isolating and selecting vital fungal strains well adapted to harsh conditions. The P. expansum strain was identified by both macro-micromorphological features and molecular analyses (btubulin gene). Using Burker Chamber, two 5 108 per mL conidial inocula suspensions (20 mL deionized water and 10 lL of tween 80) were prepared by scraping the surface of 14-d-old cultures with a loop. These suspensions were employed during the following bioaccumulation tests. The WEEE material was prepared, after the disassembling, by grinding them in a ball mill and removing the polymeric components via microwave treatment. The resulting material was a fine powder enriched in the precious metals and rare earths which were part of the WEEE. The chemical composition of the powder may vary, being urban or industrial collections of electrical and electronic waste. Therefore, the powder elemental composition was defined by means of inductively coupled plasma mass spectrometry (ICP-MS) analysis. 2.2. Mycometallurgical experiments The media for bioaccumulation test were prepared adding to a Malt Extract Agar (MEA) recipe (1 L deionized water, 20 g malt extract, 1 g peptone, 20 g glucose, 20 g agar) WEEE powder in both solid state and after dissolution in concentrated nitric acid, as
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shown in Table 1. The pH of all the media was adjusted to 5.5 using sodium carbonate (Na2CO3). The solutions were mixed and sterilized by autoclaving at 121 °C for 15 min. In addition, a control medium (MEA) was prepared. The media were put in 9 cm Ø Petri dishes and a 9 cm Ø Cellophane Membrane Backing BioradÒ disc was put on the surface layer of each dish in order to guarantee the complete separation of mycelial biomass from the culture media. Later, on each dish, 1 mL of conidial suspensions of P. expansum strain was inoculated and then incubated at 24 °C for three weeks. After this period, the fungus completely covered the plates, the Cellophane Membrane discs were removed gently, and the mycelial biomasses were scraped from their surface by using a plastic scraper. The P. expansum biomass and a sample of each solid medium were dried in drying stove for 24 h at 60 °C and stored in FalconÒ tubes. The bioaccumulation experiments were conducted in triplicate. During each test, 20 Petri dishes were employed to achieve a high amount of fungal biomass for the subsequent analysis. An aliquot of the dried P. expansum biomass was analyzed by ICP-MS, whereas the majority of the fungal biomass was then employed for the acid digestion and recovery of the bioaccumulated elements. 2.3. Acid digestion technique The digestion of the dried P. expansum biomass was carried out in a strong acid solution to completely destroy the fungus organic matrix in order to recover the precious metals and REEs bioaccumulated therein. Particularly, the digestion was performed by the dissolution of the dried fungus in nitric acid solution (65 mass%) at 50 °C under chemical hood thus obtaining a solution without any residue. 2.4. Analytical methods The total metal content of the WEEE powder and dried mycelium was analyzed by ICP-MS at the ALS Analytical Lab (Sweden). The concentration of elements was measured in triplicate for quality measurement assurance and the percentage coefficients of relative standard deviation were below 10%, reaching maximum values of about 25% only for those concentrations close to the detection limit of elements. 3. Results and discussions Table 2 reports the amount of each element in the WEEE powder. The results, as expected, highlighted, on the one hand, the high concentration of several toxic metals (Cu, Ag, Al, etc.) and, on the other hand, the presence of several REEs (La, Nd, Tb) in a very low concentration. Table 2 also shows the mycelial biomass to media culture element concentration ratio mean value for each test. The ICP-MS analyses confirmed the great uptake capability of the fungal strain tested. Our experimental results concerning the bioaccumulation capability of P. expansum agree with the works on the same concerns cited in Introduction. More in detail, after three weeks of incubation, the dishes with WEEE enriched media showed the same
Table 1 Amount of solid powder (P1 and P2) and powder acid solution (Sol1) added to MEA. Samples
Solid powder conc. in 1 L MEA
P1 P2
0.0800 g/L 1.2500 g/L
Sol1
Powder acid solution 2% wt/vol 5 mL/L
Table 2 Recovery efficiency (expressed as the ratio of element concentration in fungus to element concentration in medium) calculated in each test (P1, P2, SOL1). Element
WEEs powder conc. (ppm)
P1/RE
P2/RE
SOL1/RE
Ag Al Au Cu Fe La Nd Pd Pt Sn Tb Y
6130 9722 5227 4817 72,616 2 6 40 1.7 1174 0.5 19.3
0.98 18.64 0.023 2.78 60.59 390.63 121.04 # # 11.39 1520 47.73
0.007 5.89 0.08 1.39 77.56 17.2 3.33 # # 31.89 # 0.22
0.66 4.46 0.16 24.71 20.49 85.81 15.91 # # 36.93 # 3.09
growth rate of control dishes (plate covered completely) and the same pH (5.5), suggesting that the tested strain may tolerate the high concentrations of heavy metals of the WEEE powder added to the media culture (see Table 2). Moreover, due to the variability of the WEEE powders chemical composition, the potential recovery efficiency - RE (Jakubiak et al., 2013) has been considered as the parameter to evaluate both the bioaccumulation capability and relationships between the fungus species and the physical state of the employed WEEE derivate. The RE value is expressed as the ratio of metal concentration in fungus to the initial metal concentration in medium. The designed protocol allows the complete recovery of all the metals absorbed by the fungi. It is worth noting that the percentage of REEs that can be recovered from fungi after the bioabsorption process is about 99%. The results in Table 2 prove the bioaccumulation capability of our strain. The RE values in Table 2 underlines the exceptional bioconcentration capability of this fungus for lanthanum (up to 200 times as in the WEEE powder) in all three tests, and for terbium (up to 3000 times as in the WEEE powder) only in P1 test. In addition, the results highlight a higher bioaccumulation capability in the mycelial biomass grown on the media enriched with WEEE in the powder state than in the solution state. It can be hypothesized that the metal in the ionic form obtained from strong acid dissolution is not the best one for the P. expansum; on the contrary, in spite of the great stability of solid powder, the fungal metabolites (citric acid, oxalic acid, etc.) decomposed elements in the powder in a more suitable form for the bioaccumulation (Gadd et al., 2012). An alternative hypothesis is that fungi, like other organisms, may biosorb only complex molecules instead of simple ionic elements (Ahalya et al., 2003). The same comparison about the WEEE powder added after acid dissolution highlights different and less efficient results. If the WEEE derivate has been added in the solid state, the fungus shows the higher concentration ratio for the elements La and Tb. Furthermore, this ratio is considerably better for the sample with a low WEEE concentration in the media culture. In this context, Brandl et al. (2001) showed that high lanthanides concentration in the culture media may inhibit fungal growth and bioaccumulation, whereas the employment of lower REE amount may allow the efficient and great bioaccumulation and bioconcentration of the same metals. Moreover, they studied a two-step approach to solve the problem and favor fungal germination by inoculating REE enriched media with fungal biomass grown on control media. Owing to the fact that the four REEs in the WEEE powder (La, Nd, Tb, and Y) have shown interesting RE values, considering both their initial concentration in the WEEE powder and their importance under different points of view, a comparison among their
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RE values in the three experiments has been done and the results are shown in Fig. 1. As concerns the two light lanthanides, the fungus exhibits a better concentration capability in the P1 experiment, but also in the P2 and SOL1 measurements it presents a detectable RE value. As far as terbium is concerned, the fungus demonstrates a strong concentration capability in the P1 experiment, whereas in P2 and SOL1 media culture this capability falls to zero. Yttrium (which has ionic radius similar to terbium and can be considered a heavy rare earth) is well concentrated in the P1 media, whereas in the other two cultures the RE factor is low. In consideration of the above, the method here proposed is significantly advantageous, especially for the following reasons: (i) the extraction procedure operates at room temperature and has a very low impact, owing to the fungus ability to bioaccumulate REEs and precious metals from waste materials; (ii) the method does not require continuous monitoring and control, because after culturing on the waste materials, the fungus growth and simultaneous element absorption proceed autonomously; (iii) the whole amount of the different metals bioaccumulated by the fungus can be completely recovered in the concentrated acid solution; (iv) the fungus growing acts as a bioconcentrator thus increasing the process yield; (v) the implementation of the method does not require a particularly complex plant (a bioreactor may simply consist of a bed of reaction); and (vi) the elements can be recovered in a minimum volume of strong acid that, at the same time, eliminates the organic fungal mass. Finally, our process of selective extraction from waste of the rare earth metals leads to the production of a very concentrated acid solution of the rare earths ions. This solution can be useful (without further treatment) in different fields: for instance, in agronomy it’s well known that a low concentration of REEs can be used to amend common livestock manures in order to control the phosphorus release (Buda et al., 2010). In the field of corrosion inhibition for the metallic alloys, nitrate or chloride REE solutions (in particular cerium) are widely used to test protective treatments, which are different from the usual artifact coating (Mouanga et al., 2015). The concentrated metal ions solution so obtained allows, if desired, recovering the pure metals or salts by subsequent well-known processes, such as electrodeposition and precipitation. As a consequence, these metal solutions have a great economic value for the contained elements. For example, the price of TbCl36H2O salts is about 950 €/kg. Owing to this process and especially to the pre-concentration activity of filamentous fungi,
Fig. 1. Comparison of the RE values for the four lanthanides La, Nd, Tb and Y in the three different experiments: P1 (solid powder 0.08 g/L), P2 (solid powder 1.25 g/L), SOL1 (powder acid solution 2% wt/vol 5 mL/L).
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obtaining a high lanthanide concentrated solution is possible to reduce the recovery costs.
4. Conclusions The protocol presented in this work may be considered a novel complete ‘‘green” recycling technique by mycometallurgy. The experimental results demonstrate that the tested P. expansum strain, isolated from ecotoxic metal contaminated soil, is able to bioaccumulate metal elements. During three weeks of cultivation, this isolated fungal strain concentrated in their own mass Lanthanum (up to 390 ppm) and Terbium (up to 1520 ppm). The acid digestion of the fungal biomass produced a high lanthanides concentrated solution exploitable for several different applications. However, further deeper studies about the mechanisms affecting this process are necessary in order to better understand its potentiality, efficiency, and economic feasibility. In particular, some tests under different environmental conditions (T, pH, CO2, etc.) are in progress to finely tune the process. Eventually, a team of chemical engineers will be involved in our project to actually and efficiently industrialize the designed process.
References Ahalya, N., Ramachandra, T.V., Kanamadi, R.D., 2003. Biosorption of heavy metals. Res. J. Chem. Environ. 7 (4), 71–79. Amin, M.M., El-Aassy, I.E., El-Feky, M.G., Sallam, A.M., El-Sayed, E.M., Nada, A.A., Harpy, N.M., 2014. Fungal leaching of rare earth elements from Lower Carboniferous carbonaceous shales, Southwestern Sinai, Egypt. Rom. J. Biophys. 24, 25–41. Aruguete, D.M., Aldstadt, J.H., Mueller, G.M., 1998. Accumulation of several heavy metals and lanthanides in mushrooms (Agaricales) from the Chicago region. Sci. Total Environ. 224, 43–56. Beolchini, F., Fonti, V., Dell’Anno, A., et al., 2012. Assessment of biotechnological strategies for the valorization of metal bearing wastes. Waste Manage. 32, 949– 956. Binnemans, K., Jones, P.T., Blanpain, B., Van Gerven, T., Yang, Y., Walton, A., Buchert, M., 2013. Recycling of rare earths: a critical review. J. Clean. Prod. 51, 1–22. Brandl, H., Bosshard, R., Wegmann, M., 2001. Computer-munching microbes: metal leaching from electronic scrap by bacteria and fungi. Hydrometallurgy 59, 319– 326. Buda, A.R., Church, C., Kleinman, P.J.A., Saporito, L.S., Moyer, B.G., Tao, L., 2010. Using rare earth elements to control phosphorus and track manure in runoff. J. Environ. Qual. 39, 1028–1035. Carbone, C., Zotti, M., Pozzolini, M., Giovine, M., Di Piazza, S., Mariotti, M., Lucchetti, G., 2014. Mineral-microorganism interactions in Acid Mine Drainage environments: preliminary results. Geophys. Res. Abstr. 16, 11906. Ceci, A., Maggi, O., Pinzari, F., Persiani, A.M., 2012. Growth responses to and accumulation of vanadium in agricultural soil fungi. Appl. Soil Ecol. 58, 1–11. Chi, X., Streicher-Porte, M., Wang, M.Y.L., ReuterM, A., 2011. Informal electronic waste recycling: a sector review with special focus on China. Waste Manage. 31, 731–742. Cui, J., Zhang, L., 2008. Metallurgical recovery of metals from electronic waste: a review. J. Hazard Mater. 158, 228–256. D’Aquino, L., Morgana, M., Carboni, M.A., Staiano, M., Vittori Antisari, M., Re, M., Lorito, M., Vinale, F., Abadi, K.M., Woo, S.L., 2009. Effect of some rare earth elements on the growth and lanthanide accumulation in different Trichoderma strains. Soil Biol. Biochem. 41, 2406–2413. Das, N., 2010. Recovery of precious metals through biosorption - a review. Hydrometallurgy 103, 180–189. Dudeney, A.W.L., Sbai, M.L., 1993. Bioleaching of rare-earth-bearing phosphogypsum. In: Torma, A.E., Wey, J.E., Lakshmanan, V.L. (Eds.), Biohydrometallurgical Technologies Yhe minerals, Metals, & Material Society. Jackson Hole, pp. 39–47. Gadd, M.G., 2007. Geomycology: biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation. Mycol. Res. 3, 3–49. Gadd, M.G., Rhee, Y.J., Stephenson, K., Wei, Z., 2012. Geomycology: metals, actinides and biominerals. Environ. Microbiol. Rep. 4, 270–296. Gahan, C.S., Srichandan, H., Kim, D.J., Akcil, A., 2013. Bio-hydrometallurgy and its applications: a review. In: Thatoi, H.N. (Ed.), Advances in Biotechnology. Indian Publisher, New Deli, India, pp. 71–100. Hennebel, T., Boon, B., Maes, S., Lenz, M., 2015. Biotechnologies for critical raw material recovery from primary and secondary sources: R&D priorities and future perspectives. New Biotechnol. 32, 121–127.
600
S. Di Piazza et al. / Waste Management 60 (2017) 596–600
Horiike, T., Yamashita, M., 2015. A new fungal isolate, Penidiella sp. strain T9, accumulate the rare earth element dysprosium. Appl. Environ. Microbiol. 81, 3062–3068. Jakubiak, M., Giska, I., Asztemborska, M., Bystrzejewska-Piotrowska, G., 2013. Bioaccumulation and biosorption of inorganic nanoparticles: factors affecting the efficiency of nanoparticle mycoextraction by liquid-grown mycelia of Pleurotus eringi and Trametes versicolor. Mycol. Progress. 13, 525–532. Johnson, D.B., 2014. Biomining — biotechnologies for extracting and recovering metals from ores and waste materials. Curr. Opin. Biotechnol. 30, 24–31. Lee, C.H., Chen, Y.J., Liao, C.H., 2013. Selective leaching process for neodimiumrecovery from scrap Nd-Fe-B magnet. Metall. Mater. Trans. A 44 (13), 5825–5833. Lee, J.C., Dhar Pandey, B., 2012. Bio-processing of solid wastes and secondary resources for metal extraction – a review. Waste Manage. 32, 3–18. Mouanga, M., Andreatta, F., Druart, M.-E., Marin, E., Fedrizzi, L., Olivier, M.-G., 2015. A localized approach to study the effect of cerium salts as cathodic inhibitor on iron/aluminum galvanic coupling. Corros. Sci. 90, 491–502. Ongondo, F.O., Williams, I.D., Cherrett, T.J., 2011. How are WEEE doing? A global review of the management of electrical and electronic wastes. Waste Manage. 31, 714–730. Onofri, S., Anastasi, A., Del Frate, G., Di Piazza, S., Garnero, N., Guglielminetti, M., Isola, D., Panno, L., Ripa, C., Selbmann, L., Varese, G.C., Voyron, S., Zotti, M., Zucconi, L., 2011. Biodiversity of rock, beach and water fungi in Italy. Plant Biosyst. 145, 978–987. Ozaki, T., Suzuki, Y., Nankawa, T., et al., 2006. Interactions of rare earth elements with bacteria and organic ligands. J. Alloys Compd. 408–412, 1334–1338. Pant, D., Joshi, D., Upreti, M.K., Kotnala, R.K., 2012. Chemical and biological extraction of metals present in E waste: a hybrid technology. Waste Manage. 32, 979–990. Pethkar, A.V., Kulkarni, S.K., Paknikar, K.M., 2001. Comparative studies on metal biosorption by two strains of Cladosporium cladosporioides. Bioresour. Technol. 80, 211–215.
Qu, Y., Lian, B., 2013. Bioleaching of rare earth and radioactive elements from red mud using Penicilium tricolor RM-10. Bioresour. Technol. 136, 16–23. Rabatho, J.P., Tongamp, W., Takasaki, Y., Haga, K., Shibayama, A., 2013. Recovery of Nd and Dy from rare earth magnetic waste sludge by hydrometallurgical process. J. Mater. Cycles Waste Manage. 15, 171–178. Roccotiello, E., Marescotti, P., Di Piazza, S., Cecchi, G., Mariotti, M.G., Zotti, M., 2015. Biodiversity in metal contaminated sites – problem and perspective – a case study. In: Lo, Y.H., Blanco, J.A., Roy, S. (Eds.), Biodiversity in Ecosystems - Linking Structure and Function. InTech, pp. 581–600. Shen, H., Forssberg, E., 2003. An overview of recovery of metals from slags. Waste Manage. 23, 933–949. Takeda, O., Okabeb, T.H., Umetsu, Y., 2006. Recovery of neodymium from a mixture of magnet scrap and other scrap. J. Alloys Compd. 408–412, 387–390. Tsuruta, T., 2007. Accumulation of rare earth elements in various microorganisms. J. Rare Earths. 25, 526–532. U.S. Geological Survey, 2011. Mineral Commodity Sommarie. U.S. Geological Survey, Washington. Wang, R., Xu, Z., 2014. Recycling of non-metallic fractions from waste electrical and electronic equipment (WEEE): a review. Waste Manage. 34, 1455–1469. Zhuang, W.Q., Fitts, J.P., Ajo-Franklin, C.M., et al., 2015. Recovery of critical metals using biometallurgy. Curr. Opin. Biotechnol. 33, 327–335. Zotti, M., Di Piazza, S., Roccotiello, E., Lucchetti, G., Mariotti, M.G., Marescotti, P., 2014. Microfungi in highly copper-contaminated soils from an abandoned Fe– Cu sulphidemine. growth responses, tolerance and bioaccumulation. Chemosphere 117, 471–476.
Websites http://news.xinhuanet.com/english/business/2012-06/20/c_131665123_4.htm (http://ec.europa.eu/environment/waste/weee/index_en.htm).
