E-waste: An overview on generation, collection, legislation and recycling practices

Resources, Conservation and Recycling 122 (2017) 32–42

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Resources, Conservation and Recycling journal homepage: www.elsevier.com/locate/resconrec

Review

E-waste: An overview on generation, collection, legislation and recycling practices Amit Kumar a,∗ , Maria Holuszko a , Denise Crocce Romano Espinosa b a b

NBK Institute of Mining Engineering, University of British Columbia, 517-6350 Stores Road, Vancouver, BC, V6T 1Z4, Canada Polytechinc School, Chemical Engineering Department, University of Sao Paulo, Sao Paulo, SP, Brazil

a r t i c l e

i n f o

Article history: Received 27 July 2016 Received in revised form 2 November 2016 Accepted 29 January 2017 Keywords: Electronic waste Electronics production Recycling Environment

a b s t r a c t E-waste is one of the fastest growing waste streams in the world in terms of volume and its environmental impact on the planet. The existence of precious metals in the e-waste stream provides a major economic benefit for recycling industries but due to the presence of hazardous chemicals, a proper recycling technique is required prior to the disposal of the e-waste. This paper presents an overview of the statistics on global e-waste generation and the sales of new electrical equipment and electronics in general. The total amount of e-waste produced has reached approximately 41 million tonnes in 2014 and increasing at a rate of 3–5% every year. A correlation between e-waste generated, gross domestic product and population of the country has also been explored that suggested that the GDP of any country has a direct correlation with the amount of e-waste produced by that country. The population of the country doesn’t have a significant impact. The paper also describes the importance and benefits of recycling are emphasized while presenting the techniques currently used by the recycling facilities. © 2017 Elsevier B.V. All rights reserved.

Contents 1. 2. 3. 4. 5. 6.

7.

8. 9.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Definition and categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Objectives and methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Global sales of electrical and electronic products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Recycling benefits/reasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 6.1. Economic reasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 6.2. Environmental reasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 6.3. Public health and safety reasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Current practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.1. Official take-back system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.2. Disposal with mixed residual waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.3. Collection outside official take-back systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 7.4. Informal collection and recycling in developing countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 E-waste legislations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Estimating quantities for e-waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 9.1. Sales obsolescence method (SOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 9.2. Survey scale-up method (SSUM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 9.3. Hybrid sales obsolescence-trade data method (HSOTDM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 9.4. Mass balance method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

∗ Corresponding author. E-mail address: [email protected] (A. Kumar). http://dx.doi.org/10.1016/j.resconrec.2017.01.018 0921-3449/© 2017 Elsevier B.V. All rights reserved.

A. Kumar et al. / Resources, Conservation and Recycling 122 (2017) 32–42

10.

11.

33

Current recycling technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.1. Pre-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.1.1. Dismantling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.1.2. Shredding/comminution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.1.3. Mechanical separation/enrichment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.2. End-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.2.1. Pyro-metallurgy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.2.2. Hydro-metallurgy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 10.2.3. Bio-metallurgy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

1. Introduction Electronic waste is a growing concern around the world. With technological advancements, industries have moved towards greater automation, which has increased the electrical and electronic equipment usage. Electrical and electronics products have become common in the daily life of the average consumer, frequently used in manufacturing and other industries. At the same time, the development of advanced, faster and more reliable computing and processing technologies has led to a decreased product life cycle driving consumers to purchase newer and more current in terms of technology products while discarding older products. All these developments have in turn led to an exponential increase in e-waste generation. According to Balde et al. (2015), the total ewaste generated worldwide was estimated at approximately 41.8 million tonnes in 2014 (5.9 kg/inhabitant). Namias (2013) suggested that the electronic waste contains up to 60 metals including copper, gold, silver, palladium and platinum. Recovery of these metals from the e-waste could reduce the total global demand for new metal production to some extent. E-waste recycling also helps to reduce the amount of material disposed of in the landfills. Even with all the potential benefits only 15% of the global e-waste is fully recycled (Heacock et al., 2015).

2. Definition and categories Any electrical and electronic product that had been discarded is considered as an electronic waste or referred to in short as ewaste. A well-rounded definition is very important to have in order to formulate policies and disposal standards. Solving the e-waste problem (SteP) is an international initiative that works on developing solutions for the e-waste issue around the globe. According to Step Initiative (2014), “E-waste is a term used to cover items of all types of electrical and electronic equipment (EEE) and its part that have been discarded by the owner as waste without intention of re-use.” Balde et al. (2015) divided the electronic waste into six distinct categories:

1. Temperature exchange equipment: refrigerators, freezers, air conditioner, heat pump; 2. Screens & monitors: televisions, monitors, laptops, notebooks, tablets; 3. Lamps: fluorescent lamps, LED lamps, high-intensity discharge lamps; 4. Large equipment: washing machines, clothes dryers, electric stoves, large printing machines, copying machines, photovoltaic panels; 5. Small equipment: vacuum cleaners, toasters, microwaves, ventilation equipment, scales, calculators, radio, electric shavers,

kettles, camera, toys, electronic tools, medical devices, small monitoring and control equipment; 6. Small IT and telecommunication equipment: mobile phones, GPS, pocket calculators, routers, personal computers, printers, telephones. Based on the European Union Directive, Widmer et al. (2005) and Gaidajis et al. (2010) have also included medical devices, toys, leisure and sports equipment and automatic dispensers as e-waste. However, these equipment are no longer included in the European Union Directive (The European Commission, 2012). 3. Objectives and methodology The major objective of this review paper is to analyze the influence of electronic waste on the society and environment and establish the major factors affecting the generation of electronic waste around the world. The secondary objectives and adopted approaches are listed below. • Collecting data for e-waste generation. The report published by the United Nations University was used here to gather data related to e-waste generation. • Analyzing the factors affecting e-waste generation. The data reported by United Nations University was combined with the economic and population data from World Bank to establish the correlation between various indices. • Analyzing the future trend of e-waste: To study the future trends, the electronic and electrical equipment sales data were collected as well as the estimated life of various products. • Understanding the benefits and reasons for recycling. The benefits analysis of e-waste recycling was performed using values of materials present in the e-waste and environmental and public health issues associated with the hazardous materials present in e-waste. Along with these objectives, the current practices to deal with e-waste and most common recycling methods adopted are also presented in this paper along with the benefits and issues associated with these processes. 4. Statistics Balde et al. (2015) estimated that the total e-waste produced around the world was 41.8 million tonnes in 2014 and expected to rise to approximately 50 million tonnes by 2018. The estimated annual growth rate for the e-waste stream is 3–5% (Cucchiella et al., 2015). This rate is about three times faster than other waste streams (Singh et al., 2016). The amount of e-waste in different categories is provided in Table 1. Table 1 shows that the small and large equipment, temperature exchange equipment and screens/monitors are the major contrib-

A. Kumar et al. / Resources, Conservation and Recycling 122 (2017) 32–42

Table 1 E-waste in different categories.

9,000

30

USA

Categories

Amount (in million tonnes)

Temperature exchange equipment Screens & monitors Lamps Large equipment Small equipment Small IT and telecommunication equipment

7.0 6.3 1.0 11.8 12.8 3.0

Total e-waste (in kt)

8,000

25

China

7,000 6,000

20

5,000

R² = 0.0563

4,000

15 R² = 0.9583

3,000

10

2,000

5

1,000

0 20,000

0 0

5,000

E-waste per inhabitant (in kg)

34

10,000 15,000 GDP (in billion dollars) Total e-waste E-waste/inh.

Fig. 2. Total e-waste and e-waste/inh. vs. GDP.

8,000

Total e-waste (in kt)

China

20

5,000 R² = 0.3897

4,000

15

3,000

India

5 R² = 0.0504

0 0

Table 2 Total e-waste categorized by continents. Amount (kg/inh.)

Africa Americas (north & south) Asia Europe Oceania (Australia)

1.9 11.7 16.0 11.6 0.6

1.7 12.2 3.7 15.6 15.2

utors to the electronic waste stream. Photovoltaic panels are a new type of waste added to the e-waste category. The total amount of global PV waste stream is expected to reach 43,500–250,000 metric tons by the end of 2016 and will reach 5.5–6 million tonnes by 2050 (Weckend et al., 2016). Fig. 1 shows the expected growth in waste PV panels. This shows that the e-waste stream is a rapidly evolving waste streams due to the development of newer products. Similarly, the vast majority of CRT screens are expected to be collected within next 10 years and it will gradually decrease (Singh et al., 2016). The amount of electronic waste generated by continents and per inhabitants is listed in Table 2. It confirms the fact that e-waste is a concern all over the world but definitely, it is concentrated in the regions where economic development is the greatest. The e-waste data provided by Balde et al. (2015) is combined with the GDP and population data obtained from World bank database (2014) in order to correlate the total e-waste generated in 50 countries with the highest gross domestic product (GDP) and with the highest population as shown in Figs. 2 and 3. Fig. 4 shows the correlation between the e-waste and GDP per inhabitant. Fig. 2 shows a linear relationship between the GDP and the amount of e-waste generated in a country whereas Fig. 3 suggests that there is no significant correlation or trend between the population and the amount of e-waste produced by the country. The two outliers in Fig. 2 are the United States and China. These two countries have significantly higher than any other country GDP ($17,419.0 billion and $10,360.1 billion) and also generate high amounts of e-waste (7072 and 6033 kt) due to their strong economic development and larger population. In Fig. 3, the three outliers are the United States, China, and India. As mentioned earlier, USA and China have high GDP and high share in e-waste

200

400

600 800 1,000 1,200 Population (in millions) Total e-waste E-waste/inh.

1,400

0 1,600

Fig. 3. Total e-waste and e-waste/inh. vs. population.

8,000

40

7,000

35 R² = 0.8327

6,000

30

5,000

25

4,000

20

3,000

15

2,000

10 R² = 0.0113

1,000

5

0 0

20,000

40,000 60,000 80,000 GDP per capita (in dollars) Total e-waste E-waste/inh.

1,00,000

E-waste per inhabitant (in kg)

Amount (in million tonnes)

Total e-waste (in kt)

Continents

10

2,000 1,000

Fig. 1. Estimated PV panel waste (Weckend et al., 2016).

25

6,000

E-waste per inhabitant (in kg)

30

USA

7,000

0 1,20,000

Fig. 4. Total e-waste and e-waste/inh. vs. GDP per capita.

generation. On the other hand, the larger population in India is responsible for an increased share of total e-waste generation (1641 kt), but relatively low e-waste generation per inhabitant due to its lower GDP. Fig. 4 indicates that the electronic waste generated per inhabitant in any country is correlated with the per capita income of the inhabitants which suggests that the amount of electronic waste generated by every inhabitant increases with the increase in their individual wealth hence purchasing power. In summary, Figs. 2–4 suggest that a country with higher GDP is most likely to have a higher e-waste generation, on the other hand, a country with larger population doesn’t necessarily produce significantly larger amount of e-waste if the purchasing power and GDP is lower. As an example, a comparison of e-waste generation in India and China is shown in Table 3. It shows that both the countries have the similar population but China has higher GDP and higher GDP per capita which in turns boosts the total e-waste generation. With the increasing purchasing power of the residents in the developing countries, it is expected that the total e-waste genera-

A. Kumar et al. / Resources, Conservation and Recycling 122 (2017) 32–42 Table 3 E-waste generation comparison in India and China.

Population GDP GDP per capita Total e-waste generation E-waste generation per capita

35

Table 6 Value of materials present in e-waste stream (Balde et al., 2015).

Units

India

China

Material

Amount (kt)

Value (million Euros)

million $ billion $ $ kt kg

1295.3 2066.9 1595.7 1641 1.3

1364.3 10,360.1 7593.9 6033 4.4

Iron/steel Copper Aluminum Gold Silver Palladium Plastics

16,500 1900 220 0.3 1.0 0.1 8600

9000 10,600 3200 10,400 580 1800 12,300

Table 4 Number of EEE units sold. Items

Units (in millions)

Source

Year

Android phones iPhone 6 Total smartphones Laptop & desktop LCD TV Plasma TV CRT TV Total TV Printers e-book reader Home appliances Electric ovens Refrigerator Automatic washers

1675.45 19.75 12,444.89 238.5 5.79 0.63 0.55 7.08 106,000 20.2 583 0.733 (USA) 11.13 (USA) 9.68 (USA)

StatisticBrain (2015) StatisticBrain (2015) Gartner (2014) StatisticBrain (2015) StatisticBrain (2015) StatisticBrain (2015) StatisticBrain (2015) StatisticBrain (2015) StatisticBrain (2015) StatisticBrain (2015) Statista (2016) Statista (2016) Statista (2016) Statista (2016)

2015 2015 2015 2016 2015 2015 2015 2015 2014 2015 2013 2015 2013 2013

Table 5 Estimated lifespan of EEE (Ely, 2014).

Fig. 5. Potential revenue from e-waste streams (Cucchiella et al., 2015).

6.1. Economic reasons

Items

Average life (years)

Flat panel TV Digital camera DVD player or recorder Desktop computer Blue-ray player Video game console Laptop/notebook Tablet Cellphones (not smartphones) Smartphones

7.4 6.5 6.0 5.9 5.8 5.7 5.5 5.1 4.7 4.6

tion for countries like China, India and Brazil will soon surpass the developed countries (Li et al., 2015). 5. Global sales of electrical and electronic products The global sales data for various electronics and home appliances are shown in Table 4 (Gartner, 2014; Statista, 2016; StatisticBrain, 2015). The life expectancy of electronic products listed by Ely (2014) is shown in Table 5. Tables 4 and 5 suggest that all the phones and laptops/desktops sold in the year 2014–15 will contribute to the e-waste stream within 4–5 years. According to Robinson (2009), one billion computers will be discarded in next five years. Another study by Ala-Kurikka (2015) suggested that more than 60% of the replaced televisions were still functioning in 2012 most probably due to the technology change from CRT TVs to LCD and LED TVs which indicates that replacement period for consumer electronics is short due to the rapidly changing industry and technological advancements. With the development of newer technology, older technology gets obsolete and report to the waste stream. 6. Recycling benefits/reasons There are three main benefits/reasons for recycling a) economic benefits b) environmental benefits and c) public health and safety benefits.

From 2005–2014, the global demand for copper, tin, and silver in electronics application has been increasing while the demand for gold has been relatively stable (Golev et al., 2016). Electronic waste contains up to 60 different metals including some valuable and precious metals such as copper, gold, silver, palladium, aluminum and iron (Namias, 2013). An estimate provided by Balde et al. (2015) as shown in Table 6 evaluated the estimated value of e-waste at D 48 billion. The printed circuit board represents the most valuable part of e-waste accounting for over 40% of the total e-waste metal value (Golev et al., 2016). BullionStreet (2012) summarized that 320 t of gold and 7500 t of silver is consumed by the electronic industry every year and urban mining of e-waste could generate $21 billion each year. Cucchiella et al. (2015) showed that the notebooks, tablets, and smartphones are the most valuable categories for the e-waste stream due to the presence of a larger concentration of precious and critical metals. Almost 3–6% of the total e-waste is printed circuit boards which contain a significant proportion of valuable metals like gold, silver, gold and palladium. Golev et al. (2016) also concluded that more than 80% of gold and PGMs and over 70% of silver are locked in screens, monitors, and small It equipment. Fig. 5 shows the potential revenue per kg and per unit for some e-waste streams. The potential revenue from the printed circuit boards is $21,200/t. At the same time, the concentration of metal in the e-waste stream is significantly higher than the conventional mining operations. Studies have shown that the global ore grade are declining and mines are forced to excavate more complex and fine-grained ore deposits to meet the global metal demand (Lèbre and Corder, 2015). Table 7 shows the concentration of metals in various electronics items (Namias, 2013) and an average grade of metal in the ores excavated from mines (Desjardins, 2014; Investing News Network, 2016; McLeod, 2014; Vincic, 2015). The palladium grade is based on the average mill head grade at North American Palladium Ltd. in 2014. Table 7 clearly shows that the average grade in electronics for copper, gold, silver and palladium is significantly higher than that of an orebody extracted by the conventional mining operation.

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Table 7 Metal concentration in electronics and ore (Desjardins, 2014; Investing News Network, 2016; McLeod, 2014; Namias, 2013; Vincic, 2015). Product

Copper (% by wt)

Silver (ppm)

Gold (ppm)

Palladium (ppm)

Television board PC board Mobile phone Portable audio scrap DVD player scrap Average electronics Ore/mine

10 20 13 21 5 13.8 0.6

280 1000 3500 150 115 1009 215.5

20 250 340 10 15 127 1.01

10 110 130 4 4 51.6 2.7

Table 8 Metals present in mobile phones and run of mine ore (Electronics TakeBack Coalition, 2014).

Gold Silver Palladium Copper

Amount (kg)

Mobile phones

Run of mine ore

24 250 9 9000

1 million units ∼ 148.4 t

23,762.4 t of gold ore 1160.1 t of silver ore 3333.3 t of palladium ore 1500.0 t of copper ore

An estimate provided by Electronics TakeBack Coalition (2014) regarding the amount of various metals that can be recovered from recycling 1 million cell phones is shown in Table 8. It also shows the amount of run of mine ore that needs to be processed in order to obtain the same amount of metal based on the average metal grade shown in Table 7. It shows that the amount of run of mine ore that needs to be processed to obtain the same amount of metals is 10–160 times more than that of the waste mobile phones. The data assumes 100% recovery in both mobile phones and run of mine ore. E-waste also provides a better opportunity for an already scarce natural element such as gallium (annual production ∼215 t) and indium (annual production ∼1100 t). Both these metals have an estimated life of 20 years before it completely runs out (Li et al., 2015). From an economic point of view, the e-waste industry is also capable of creating additional jobs. 296 more jobs for every 10,000 t of material disposed of can be created by computer reuse (Electronics TakeBack Coalition, 2014). In Guiyu, China, informal e-waste recycling provided jobs to almost 100,000 people as ewaste recyclers (Heacock et al., 2015). With the similar throughput, 300–600 new treatment facilities will have to be developed in China to deal with the total generated e-waste from 2020 to 30 that can potentially provide jobs to 30,000 people (Zeng et al., 2016). 6.2. Environmental reasons The recycling industry plays a key role in environmental protection by keeping the hazardous waste out of the landfills thus reducing the risks associated with disposal. The e-waste stream contains many hazardous materials such as mercury, cadmium, lead, chromium, poly/brominated flame retardants, ozone depleting chemicals such as CFC etc. (Balde et al., 2015). Disposal of these chemicals/metals in the landfill or by incineration produce harmful effects to the environment. Well controlled and regulated landfill and incineration might provide a temporary solution to the global e-waste problem but not viable in the longer term especially for the countries with the scarcity of landmasses such as Japan and Europe and it also reduce the possibility of resource recovery. On the other hand, recycling e-waste will reduce the total global demand for new metal production, which helps to reduce the greenhouse gas emissions. According to Electronics TakeBack Coalition (2014), it requires 240 kg of fossil fuels, 22 kg of chemicals and 1.5 t of water to produce one computer with monitor.

Table 9 Recycled material energy saving over virgin materials (Cui and Forssberg, 2003). Materials

Energy saving (%)

Aluminum Copper Iron and steel Lead Zinc Paper Plastics

95 85 74 65 60 64 >80

Recycling metals from e-waste provide significant energy saving compared to virgin materials as shown in Table 9. This energy saving then directly has a direct impact on the greenhouse gas emissions due to new metal production. For example, recycling 10 kg aluminum not only provides a 90% energy saving but also prevents the creation of 13 kg of bauxite residue, 20 kg of CO2 gas and 0.11 kg of SO2 gas (Electronics TakeBack Coalition, 2014). Similarly, recycling iron and steel provides 74% of energy saving, 86% reduction in air pollution, 40% reduction in water use, 76% in reduction in water pollution, 97% reduction in mining wastes and 90% saving in virgin materials use (Cui and Forssberg, 2003). Van Eygen et al. (2016) showed that recycling of desktops and laptops provides 80 and 87% resource saving respectively as shown in Fig. 6. 6.3. Public health and safety reasons As indicated earlier, the e-waste stream contains hazardous metals and chemicals. It not only poses a threat to the environment but also to the public health and safety. Garlapati (2016) presented a list of hazardous components and chemicals present in e-waste as shown in Table 10. Table 11 shows the effect of the various hazardous material present in e-waste on the human health (Brigden et al., 2005). Balde et al. (2015) also concluded that the hazardous materials from the e-waste can impair mental development, kidney, and liver damage and have carcinogens released into the air causing lung damage. A typical recovery method in informal sector for recovering copper from the cables is to burn polyvinyl chloride in open air and acid/caustic leaching of printed circuit boards to obtain precious metals (Velis and Mavropoulos, 2016). These methods, disposal of these chemicals/metals in landfills or by incineration produce harmful effects to the environment and life can be exposed to these chemicals through water, air, soil, dust or food (Heacock et al., 2015). The amount of cadmium present in a cell phone battery have a potential to contaminate 600m3 of water (Garlapati, 2016). Scruggs et al. (2016) showed that the consumers can be exposed to the hazardous chemical while using the electronics products. Decabromodiphenylether, a common flame retardant in electronics casing, form polybrominated dibenzofurans when exposed to normal sunlight and accumulate in household and office dust and can eventually end up in the water supplies. Brigden et al. (2005) also showed the elevated levels of these hazardous materials in different e-waste processing facilities and workshops in China and India. For example, the discharge channel sediments near Guiyu to Nanyang road and Chendiandian to Guiyu road in China had elevated levels of copper (9500–45900 mg/kg), lead (4500–44300 mg/kg), tin (4600–33000 mg/kg), antimony (1390–2150 mg/kg), nickel (150–2060 mg/kg) and cadmium (13–85 mg/kg) which was 400–600 times higher than that is expected from uncontaminated river sediments. Similarly, a sample from the final spent acid wastes from an acid processing/leaching facility in Mandoli Industrial area (New Delhi, India) showed elevated levels of antimony (68 mg/l), copper (240 mg/l), lead (20 mg/l), nickel (478 mg/l), tin

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Fig. 6. Resource savings from recycling of desktops and laptops.

Table 10 Hazardous components and chemicals in e-waste. Components

Substance

Occurrence in e-waste

Halogenated Compound

Polychlorinated biphenyls Polybrominated biphenyls Polychlorinated diphenyl ether Chlorofluorocarbon Polyvinyl chloride

Condensers, transformers Fire retardants for plastics Cooling unit, insulation foam Cable Insulation

Radio-active substances

Americium

Medical equipment, fire detectors, active sensing element in smoke detectors

Heavy and other metals

Arsenic Barium Beryllium Cadmium Chromium VI Lead Lithium Mercury Nickel Rare earth elements Selenium Zinc sulphide

Light emitting diodes Getters in CRT screens Power supply boxes contains silicon controlled rectifiers and x-ray lenses Rechargeable Ni-Cd batteries, fluorescent layer in CRT screens, printer inks and toners Data tapes, floppy disk CRT screens, batteries, printed circuit boards Li-batteries Fluorescent lamps, alkaline batteries Rechargeable Ni-Cd batteries, electron gun in CRT screens Fluorescent layer Older photocopying machines Interior of CRT screens

Others

Toner dust

Toner cartridges for laser printer/copiers

Table 11 Harmful effects of hazardous materials. Materials

Effect on human health

Antimony Cadmium Lead

Severe skin problems and other health effects Damage to kidneys and bone structure, accumulate in body over time Highly toxic for human, plants and animals, irreversible effects on nervous system especially in children, accumulate in body over time Highly toxic, damage to central nervous systems and kidneys, get converted to organic methylated form that is highly bio-accumulative Cause intersex in fish, build up in food chain, damage DNA and sperm function in humans Interfere with growth hormones and sexual development, effect on immune systems, interfere with brain development in animals Suppression of immune system, liver damage, cancer promotion, damage to nervous system, behavioral changes and damage to male and female reproductive system Toxicity to wildlife and possibly humans, impacts on skin, liver, nervous systems and reproductive system Toxic to aquatic life, strong inhibitor of key enzyme system in human blood, can cause contact dermatitis and possible endocrine disruptor

Mercury Nonylphenol Polybrominated diphenyl ether Polychlorinated biphenyls Polychlorinated naphthalene Triphenyl phosphate

(340 mg/l) and zinc (2710 mg/l) along with phthalate esters and chlorophenols. These elevated levels of hazardous metals show the importance of proper recycling techniques and safer recycling facilities that can reduce the risks related to the environmental and public health and safety issues. Similar results were obtained from

formal recycling sites with elevated content of nickel, copper, lead, zinc and cadmium in Philippines (Yoshida et al., 2016). Scruggs et al. (2016) suggested that goal of Strategic Approach to International Chemicals Management of ensuring the delivery of the chemical information to all the stakeholders in the electronic

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products management chain including governments, chemical producers, manufacturers, brand owners, consumers, recyclers and waste handlers is yet not achieved. It was recommended that a list of chemicals used in the product and reporting information should be identified and streamlined software to enable automated data exchange should be implemented. The materials tracking in the product chain is also important to identify the bottleneck in the product chain. 7. Current practices According to Widmer et al. (2005), about 70% of heavy metals in US landfills comes from e-waste. Balde et al. (2015) classified the current practices adopted to deal with e-waste into four categories. 7.1. Official take-back system Fig. 8. Global scenario of e-waste management.

This method is mostly observed in developed countries where e-waste is collected by municipalities (curbside collection, municipal collection points), retailers or commercial pick-up services and then sent for further processing to different centers. 7.2. Disposal with mixed residual waste This practice is mostly observed in developing countries where e-waste is disposed of with the household waste that goes to landfills or incineration and has a very low chance of separation. In the end, it adds up to the toxic leaching in a landfill or harmful emissions in the air if incinerated. 7.3. Collection outside official take-back systems This practice is mostly observed in developed countries where e-waste is collected by individual waste dealers or companies and then sent to metal recycling, plastic recycling or exported. An estimated 50%–80% of total e-waste is shipped from the USA to the developing countries (Namias, 2013). According to Cucchiella et al. (2015) almost 50% of the e-waste generate by the developed countries is illegally is exported to China and a significant quantity also goes to India, Pakistan, Vietnam, Philippines, Malaysia, Nigeria, Ghana and possibly Mexico and Brazil. WorldLoop (2013) showed the known and suspected destination of e-waste as shown in Fig. 7. Golev et al. (2016) suggested that the e-waste collection system in Australia and other developed countries doesn’t allow feasible material recovery within domestic borders that results in massive exports of e-waste for processing to developing countries. Adoption of better technological advancements, small scale recycling and controlled landfilling will be viable options to decrease the illegal processing and exports. Designing modular recycling system and infrastructure should be able to boost the e-waste recycling rate around the world (Li et al., 2015). 7.4. Informal collection and recycling in developing countries Mostly observed in developing countries where self-employed people engaged in collection and recycling of e-waste collect the e-waste. The collection is mostly door-to-door basis with unskilled workers. If the collected waste does not have any value, then it is dumped into the landfill or incinerated and this causes severe damage to the environment and poses serious human health risks. Informal recycling uses larger labor force and low-level technology and includes junk shops or private individuals and generate low levels of income (Yoshida et al., 2016). Four scenarios of e-waste management were reviewed by (2016) and a future outlook was proposed as shown in Fig. 8.

1. Local dumping: applies to the large part of the world where ewaste is landfilled 2. Export and dump: e-waste is exported to developing countries and dumped there 3. Low-level recovery: Mostly seen in developing countries and provides jobs and saves energy and raw materials. 4. High-level recovery: It also saves energy and raw materials. Additionally, it prevents illegal export to developing countries. 8. E-waste legislations Legislation around the world is in place to develop and practice the efficient and sustainable way of e-waste collection, recycling, and transportation. The European WEEE Directive in 2002 was developed to manage the end of life electronics in the European Union to improve the collection and efficiency of the recycling chain whereas the RoHS Directive restricted the use of certain hazardous substances in the EEE production. The collection targets are defined as a fixed amount per inhabitant (currently 4 kg). In 2016, the regulations were changed and the collection target was defined as 45% of the amount of EEE put on the market. In 2019, it will be increased to 65% of the EEE or 85% of the WEEE (Van Eygen et al., 2016). Van Eygen et al. (2016) showed that the recycling targets of WEEE in the European Union doesn’t promote the recovery of metals present in minor amounts. The Basal convention was designed in 1992 under United Nations Environment program to monitor and control the transboundary flow of hazardous wastes and their disposals. Several international organizations such as Mobile Phone Partnership Initiative (MPPI), Solving the E-waste Problem (StEP), Partnership for Action on Computing Equipment (PACE), National Electronics Product Stewardship Initiative (NEPSI) WEEE Forum were launched to control the e-waste problem (Widmer et al., 2005). Japan launched the Home Appliance Recycling Law (HARL) and Small Appliance Recycling Law to increase the recycling rate due to the scarcity of land mass for solid waste disposal. Countries like USA and Canada doesn’t have proper federal regulations to deal with the e-waste issue rather than rely on policies imposed by the provincial government for e-waste management (Li et al., 2015). The extended producer responsibility and the eco-fee are a tool to improve the e-waste collection and recycling in North America and the European Union. Australia have passed the National Waste Policy (2009) and National Television and Computer Recycling Scheme (2011) to improve the recycling rate but the e-waste management in

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Fig. 7. Known and suspected routes of e-waste dumping (WorldLoop, 2013).

Australia is not properly implemented, based on outdated targets and it lags behind the international best practices (Gough, 2016). China placed the extended producer responsibility practice in 2011 for WEEE recycling. India developed the “Guidelines for environmentally sound management of e-waste” in 2008 to classify the e-waste according to the components and compositions. The e-waste management and handling guidelines were developed in 2011 for e-waste collection and recycling. In Indonesia, there is no specific legislation for e-waste management but it is regulated as the hazardous and toxic waste under the Republic of Indonesia Act concerning Environmental protection and Management. Both Indonesia and Philippines are in the process of finalizing their ewaste legislation (Yoshida et al., 2016). Zeng et al. (2017) pointed out the two major gap in the current e-waste regulation: lack of proper concern on recovered materials and no control on substances to avoid heavy metal entering into a new product. It was suggested that knowledge base regarding the environmental risk and ecotoxicology of these substances should be illustrated and new development in the field of e-waste recycling is needed to reduce the amount of toxic substances entering in the downstream processes. There are still challenges in the implementation of these rules and regulations. The policies in place haven’t yet completely stopped the trade of toxic e-waste. The Basel Action network (BAN) tracked around 200 non-functional devices dropped off at various recycling sites in the USA and 32.5% of the tracked equipment were exported, 31% of the tracked equipment were likely to be illegal shipment (Grossman, 2016). Since a major amount of e-waste from developed countries ends up in developing nations, an international technical cooperation and support program will be important to achieve better management systems (Yoshida et al., 2016). The manufacturers, recyclers, state and federal regulators and the public need to work together to deal with the increasing volume of e-waste (Singh et al., 2016).

9. Estimating quantities for e-waste Most often data related to e-waste generation or collection are not completely available for various regions. There are several methods proposed to estimate the e-waste generation, collection, recycling, domestic and transboundary flow.

9.1. Sales obsolescence method (SOM) This model uses the sales data and lifespans of electronics obtained through survey and trends in survey collection rates. Uncertainty in data sets is incorporated using the Monte Carlo simulations (Miller et al., 2016). The sales data for a region over a time period is collected and then the lifespan of electronics product is evaluated based on use, storage, reuse data obtained from the survey over a time period. Then prediction for waste generation is performed using sales data and lifespans. Tran et al. (2016) used a similar approach to model the invisible TV inflow. The invisible inflow of electronic is the equipment that enters the market without administratively registered. It was concluded that approximately 20% of the total TV inflow in Vietnam was invisible in 2013. The major uncertainties associated come from assumptions and simplifications used for calculation. Additional and better data can improve the model prediction. 9.2. Survey scale-up method (SSUM) It uses survey data and census data to quantify the generation and collection of e-waste for a region. The estimates at the national level are produced using scaling factors. The estimates for the national level are scaled up using the data obtained from the regional level. This is achieved by comparing the national population to the surveyed population. Miller et al. (2016) showed that the data obtained using SSUM method had a lower coefficient of variation (3–6%) than the SOM (3–28%). 9.3. Hybrid sales obsolescence-trade data method (HSOTDM) This is a modified SOM method that uses sales and survey data for to estimate generation, survey collection rate to estimate collection and detailed trade data to estimate export (CEC, 2016). Since the trade data for all types of electronics are readily available for each year and also provides the estimates for the future including the destination country, hence this method is more detailed. 9.4. Mass balance method This method uses extrapolation of survey data to quantify the electronic flows. It provides the ability to estimate several used

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electronic products simultaneously with fewer data inputs. The exports are calculated using mass balance hence it has higher uncertainty and the export destination can’t be identified (CEC, 2016). 10. Current recycling technologies There are two common steps used in the recycling of e-waste around the world. a Pre-processing that includes dismantling, shredding, mechanical separation b End-processing that includes pyro/hydro/bio metallurgical treatment.

Table 12 Leaching agents for hydrometallurgical treatment (Namias, 2013). Metal

Leaching agent

Base metals Copper Gold and silver Palladium

Nitric acid Sulphuric acid or aqua regia Thiourea or cyanide Hydrochloric acid or sodium chlorate

aluminum. Different sensors are also being developed/used to separate various streams from each other. For example, infrared sensors can be used to separate different plastics whereas optical sensors can be used for glass (Kellner, 2008).

10.1. Pre-processing

10.1.3.1. Benefits. Faster automated system, reduced public health and safety issue, increased throughput, lesser mass/volume to transport for final process, less energy intensive.

This step usually deals with manual disassembly of electronic devices, removing hazardous materials and separating various streams such as metals, glass, and plastics. The remaining material that can’t be manually separated is sent for shredding and then separation of metals from plastics and glass is achieved by using processes such as magnetic and gravity separation (Namias, 2013).

10.1.3.2. Issues. Higher capital investment, not suitable for small recycling businesses, dust issue with dry systems, moisture removal issue for wet systems.

10.1.1. Dismantling Dismantling process is mainly adopted to remove the hazardous materials from the waste stream and then separating it manually into metal, plastics and glass fractions. The waste fraction that can’t be separated manually is usually shipped to a centralized location for shredding and then use mechanical techniques to achieve separation. 10.1.1.1. Benefits. Removal of hazardous materials, less dust issue, higher grade material for end-processing, more job opportunities. 10.1.1.2. Issues. Hard to dismantle newer complex technologies, time-consuming, higher spending on labor and transportation cost, additional greenhouse gas emissions due to transportation, increased risk of public health and safety. 10.1.2. Shredding/comminution This step involves decreasing the particle size of the material for subsequent processing. A number of equipment, metal shredders, hammer mills and knife mills, are currently being used for crushing and grinding the electronic waste (Schubert and Hoberg, 1997). 10.1.2.1. Benefits. Faster automated systems, reduced risk of public health and safety, increased throughput, less volume for transportation. 10.1.2.2. Issues. High dust issue, loss of material (up to 40%) as dust (Namias, 2013), increased capital investment, decreased grade for subsequent operation. 10.1.3. Mechanical separation/enrichment This step is used to separate various streams from the shredded material. Most of the units used in a recycling facility are operated dry but some researchers have shown high efficiency with a wet operation such as gravity concentration and flotation as well (Das et al., 2009; Duan et al., 2009; Veit et al., 2014). Magnetic separation is used to remove ferromagnetic materials such as iron, steel, and rare earth metals. Density separators such as air tables, air cyclones, and centrifugal separators are used to recover base metals such as copper, gold, and silver from nonmetal fractions. Eddy current separators can be used to recover

10.2. End-processing End-processing involves processes to recover valuable metals from the concentrate obtained after pre-processing and mostly used to recover and purify copper, gold, silver and palladium. The most widely used processes are pyrometallurgy, hydrometallurgy, and bio-metallurgy (Namias, 2013). 10.2.1. Pyro-metallurgy The pyrometallurgical process involves melting the materials/concentrate in a high-temperature furnace to obtain a mixture of desired metals that are further purified mostly using electrorefining. It is mostly used to recover copper, gold, silver and palladium. Iron and aluminum usually get oxidized and report to the slag (Namias, 2013). 10.2.1.1. Benefits. Higher/faster reaction rates due to high temperature and easier separation of valuable and waste. 10.2.1.2. Issues. High energy requirement, generation of dioxins, furans and volatile metals causing environmental and public health and safety issue, loss of iron and aluminum in slag, recovery of plastics is not possible, partial purity of precious metal (Khaliq et al., 2014; Veit et al., 2014). 10.2.2. Hydro-metallurgy Hydrometallurgical treatment involves leaching of the concentrate from the pre-treatment with various chemicals to dissolve the valuable metals into solution. Specific leaching agents are used to precipitating specific metals from the waste material that are finally purified using electro-winning. Table 12 lists some of the most commonly used agents to leach metals from the concentrate/waste. 10.2.2.1. Benefits. More accurate, predictable, easily controlled, less energy intensive (Veit et al., 2014). 10.2.2.2. Issues. Slow, time-consuming, the requirement of fine grinding for efficient leaching, more chemicals required, high toxicity, high reagent consumption, high cost, generation of effluent (Khaliq et al., 2014; Veit et al., 2014).

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10.2.3. Bio-metallurgy Bio metallurgical treatment is an environmentally friendly process where microbes are used to leach metal out of the waste/concentrate. This method has been gaining popularity for leaching copper and gold ore. Acidophilic bacterium Thiobacillus Ferrooxidans is most widely used microbes to leach copper and gold (Bosecker, 1997). The final purification is performed using electro-winning. 10.2.3.1. Benefits. Low operating cost, reduction in chemical usage, easier handleability of waste water/effluent, more eco-friendly (Namias, 2013). 10.2.3.2. Issues. Slower process, not fully developed for the higher metal complexity of electronic waste. One of the major issue with the e-waste recycling is the lack of formal recycling facilities around the globe. Most of the informal e-waste recycling involve manual dismantling and then metal recovery using the homemade equipment. These processes have a very low recovery. The development of proper formal recycling facilities will be able to process the e-waste more efficiently and thus improving the recovery of various metals. Providing financial and technical support to the formal and informal recycling sector in developing countries will improve the e-waste management practices. Li et al. (2015) suggested that Best Available Technology (BAT) and Best Environmental Practice (BEP) that extend BAT through the addition of pollution control should be put as the fundamental criteria for e-waste recycling. Four approaches were suggested to improve the global e-waste management and recycling. 1. The developed nations should invest in technology development and establish or expand new facilities to increase and improve the e-waste recycling system. 2. The developing nations should consider adopting legislation and improving the e-waste collection to maximize the recycling potential. 3. Mobile plant and portable recycling system will be most beneficial for small nations or regions. 4. For the regions with very little e-waste generation, several surrounding regions can unite and establish facilities for e-waste management. 11. Conclusion Electronic waste is a growing concern in the current global society and a significant amount of this e-waste is being added to the global waste inventory every year. The data provided by the United Nations University showed that the regions with greatest economic development produce most of the e-waste. A linear relation was found between the GDP and the amount of e-waste generated. Another correlation indicated that the electronic waste generated by each inhabitant increase with the increase in their individual wealth, hence purchasing power. There is no significant correlation or trend between the population and the amount of e-waste produced by the studied countries. Another important observation is that life expectancy of electronic equipment is becoming shorter and shorter, especially in the case of small electronic devices such as cellphones, tablets, and small laptops. As a results close to 1 billion devices will be discarded within 4–5 years. These staggering facts should be considered as an important incentive for recycling of e-waste. If this waste is properly recycled, it could offer an opportunity for urban mining for recovery of copper, gold, silver, palladium and others metals with an estimated value of D 48 billion. The concentration of metals in the e-waste is significantly higher than in the

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natural ores that these metals are mined from (for Au is almost 130 times higher). It can provide a large quantity of valuable metals otherwise representing a wasted stream of garbage. On the other hand, creating environmental and public health risks due to the presence of harmful elements and chemicals in their composition. Various metallurgical routes are currently being implemented to recover metals from the e-waste stream, but due to the complex nature of e-waste, new processes or improvements in the current processing technologies are required.

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