metals Review E-Waste Recycling and Resource Recovery: A Review on Technologies, Barriers and Enablers with a Focus on Oceania Jonovan Van Yken 1,2, Naomi J. Boxall 1 , Ka Yu Cheng 1,3 , Aleksandar N. Nikoloski 3 , Navid R. Moheimani 2 and Anna H. Kaksonen 1,4,* 1 Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water, 147 Underwood Avenue, Floreat, WA 6014, Australia; [email protected] (J.V.Y.); [email protected] (N.J.B.); [email protected] (K.Y.C.) 2 Algae R & D Centre, Environmental and Conservation Sciences, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia; [email protected] 3 Harry Butler Institute (Centre for Water, Energy and Waste), College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA 6150, Australia; [email protected] 4 School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia * Correspondence: [email protected]; Tel.: +61-8-9333-6253 Abstract: Electronic e-waste (e-waste) is a growing problem worldwide. In 2019, total global produc- tion reached 53.6 million tons, and is estimated to increase to 74.7 million tons by 2030. This rapid increase is largely fuelled by higher consumption rates of electrical and electronic goods, shorter life cycles and fewer repair options. E-waste is classed as a hazardous substance, and if not collected and recycled properly, can have adverse environmental impacts. The recoverable material in e-waste Citation: Van Yken, J.; Boxall, N.J.; represents significant economic value, with the total value of e-waste generated in 2019 estimated Cheng, K.Y.; Nikoloski, A.N.; to be US $57 billion. Despite the inherent value of this waste, only 17.4% of e-waste was recycled Moheimani, N.R.; Kaksonen, A.H. globally in 2019, which highlights the need to establish proper recycling processes at a regional level. E-Waste Recycling and Resource This review provides an overview of global e-waste production and current technologies for recycling Recovery: A Review on Technologies, e-waste and recovery of valuable material such as glass, plastic and metals. The paper also discusses Barriers and Enablers with a Focus on the barriers and enablers influencing e-waste recycling with a specific focus on Oceania. Oceania. Metals 2021, 11, 1313. https://doi.org/10.3390/met11081313 Keywords: e-waste; resource recovery; pyrometallurgy; hydrometallurgy; biohydrometallurgy; Oceania; metals; printed circuit boards; economics Academic Editors: Fernando Castro and Jean François Blais Received: 5 July 2021 Accepted: 16 August 2021 1. Introduction Published: 19 August 2021 When electrical and electronic equipment (EEE) reaches the end of its lifecycle it becomes electronic waste (e-waste). A total of 54 different product types are classified Publisher’s Note: MDPI stays neutral as e-waste, and these are grouped into six categories: large equipment, small equipment, with regard to jurisdictional claims in temperature exchange equipment, screens and monitors, small information exchange published maps and institutional affil- equipment and lamps (Figure1)[ 1]. The demand for EEE is increasing worldwide, fueled iations. by a rapid increase in technological advancement, increasing dependence on technology and increasing disposable income [2,3]. Economies of scale in production have resulted in a dynamic change, where EEE is more easily accessible and often more affordable to replace than to repair [4]. The generation of e-waste varies significantly worldwide, depending on Copyright: © 2021 by the authors. economic, social and political factors [1,3]. Countries producing the most e-waste include Licensee MDPI, Basel, Switzerland. China, the United States of America (USA), India, Japan, and Brazil (Figure2). In 2019, This article is an open access article a total of 53.6 million tons (Mt) of e-waste was generated globally, exceeding previously distributed under the terms and predicted numbers. It is estimated that annual e-waste generation will increase to 74.7 Mt conditions of the Creative Commons by 2030 [1]. In addition, the rate of e-waste generation is also increasing, with a current Attribution (CC BY) license (https:// generation of 3–5% [5]. creativecommons.org/licenses/by/ 4.0/). Metals 2021, 11, 1313. https://doi.org/10.3390/met11081313 https://www.mdpi.com/journal/metals Metals 2021, 11, x FOR PEER REVIEW 2 of 40 Metals 2021, 11, x FOR PEER REVIEW 2 of 40 Metals 2021, 11, 1313 2 of 40 74.7 Mt by 2030 [1]. In addition, the rate of e-waste generation is also increasing, with a 74.7current Mt by generation 2030 [1]. ofIn 3addition,-5 % [5]. the rate of e-waste generation is also increasing, with a current generation of 3-5 % [5]. FigureFigure 1. 1.The The six six categories categories of of e-waste: e-waste: (A A)) Large Large equipment, equipment, (B B)) Small Small equipment, equipment, (C C)) Temperature Temperature Figure 1. The six categories of e-waste: A) Large equipment, B) Small equipment, C) Temperature exchangeexchange equipment, equipment, (D D)) Screens Screens and and monitors, monitors, ( EE)) SmallSmall informationinformation technologytechnology and and telecommuni- telecommuni- exchancationge equipment equipment, and D) F) Screens Lamps and [1]. monitors, E) Small information technology and telecommuni- cation equipment and F) (F )Lamps Lamps [ [11].]. FigureFigure 2. 2.Annual Annual generation generation of of e-waste e-waste in in top top ten ten countries countries and and the the corresponding corresponding recycling recycling data data Figurefromfrom Forti, Forti,2. Annual 2018 2018 [5 [generation].5]. of e-waste in top ten countries and the corresponding recycling data from Forti, 2018 [5]. Globally, only 17.4% of e-waste was recycled properly in 2019, with the remaining Globally, only 17.4% of e-waste was recycled properly in 2019, with the remaining 82.6% either not recycled or not formally tracked [1]. The recycling rate has only slightly 82.6%Globally, either notonly recycled 17.4% of or e not-waste formally was recycled tracked [1]properly. The recycling in 2019, ratewith has the only remaining slightly improved from the rate calculated in 2014 (17%) [1], which indicates that measures em- 82.6%improved either fromnot recycled the rate or calculated not formally in tracked2014 (17%) [1]. The[1], recyclingwhich indicates rate has thatonly measuresslightly improvedployed to improvefrom the global rate calculated e-waste recycling in 2014 [6(17%)] have [1] not, which been ableindicates to compete that measures with the increased generation rate. The e-waste recycling rates are highest in Europe (Figure3), with countries such as Germany and the United Kingdom (UK) recycling more than 50% of Metals 2021, 11, x FOR PEER REVIEW 3 of 40 Metals 2021, 11, 1313 employed to improve global e-waste recycling [6] have not been able to compete with3 the of 40 increased generation rate. The e-waste recycling rates are highest in Europe (Figure 3), with countries such as Germany and the United Kingdom (UK) recycling more than 50% ofthe the e-waste e-waste generated generated in 2017in 2017 [5]. [5] In. contrast, In contrast, countries countries in Asia in andAsia South and South America, America, such as suchIndia as (0.92%), India (0.92%), Russia (5%),Russia and (5%), Brazil and (0.006%) Brazil (0.006%) have low have e-waste low recyclinge-waste recycling rates [5]. rates Often, [5]poor. Often, recycling poor recycling rates are duerates to are the due lack to of the legislation lack of legislation governing govern the collection,ing the collection, processing processingand recovery and ofrecovery materials of materials from e-waste, from e as-waste, well as as thewell lack as the of infrastructurelack of infrastructure for e-waste for e-processingwaste processing [1,5]. This[1,5]. can This be can seen be inseen the in European the European Union, Union, which which has has a Waste a Waste Electrical Elec- tricaland Electronicand Electronic Equipment Equipment (WEEE) (WEEE) directive directive that covers that covers the entire the populationentire population and sets and the setsstandards the standards for e-waste for e recycling.-waste recycling. This is oneThis of is theone factors of the enablingfactors enabling the European the European Union to Unionhave theto have highest the recyclinghighest recycling rate globally rate globally in 2019 [in1]. 2019 [1]. FigureFigure 3. 3. (A(A) Total) Total e- e-wastewaste generation, generation, (B (B) )e- e-wastewaste generated generated per per capita capita and and (C (C) )recycling recycling rate rate in in variousvarious regions regions in in 2019 2019 [5 [].5]. EE-waste-waste from from high high quantities quantities of of post post-consumer-consumer products products is is among among the the most most complex complex andand persistent persistent typetype ofof municipal municipal waste waste generated generated by society by society [7]. Technological [7]. Technological advance- ment enables the manufacture of electronic products that are more efficient and less resource-intensive yet are more complex in nature consisting of a diverse range of ma- terials [8]. Often, the heterogeneity of materials is governed by the application, as well as its structure such as the type, thickness and layers of plastic, soldering and adhesive Metals 2021, 11, x FOR PEER REVIEW 4 of 40 advancement enables the manufacture of electronic products that are more efficient and Metals 2021, 11, 1313 less resource-intensive yet are more complex in nature consisting of a diverse range4 of 40of materials [8]. Often, the heterogeneity of materials is governed by the application, as well as its structure such as the type, thickness and layers of plastic, soldering and adhesive usedused[ [9]9].. AA keykey hurdlehurdle inin recyclingrecycling e-wastee-waste lieslies inin thethe highlyhighly heterogeneousheterogeneous and and complex complex naturenature ofof itsits composition,composition, whichwhich makesmakes itit moremore difficultdifficult toto processprocess whenwhen itit is is mixed mixed with with generalgeneral householdhousehold waste.waste.