# E-Waste Reverse Supply Chain: A Review and Future Perspectives
## 2 Electronic Waste Issues  
In today's business world with a competitive electronics market, the production of electronic equipment is rapidly growing because customers are likely to own the latest models with more advanced functions and attractive designs. This leads to the amount of e-waste growing speedily, reaching around 41.8 million tonnes in 2014 [3]. The quantity of e-waste produced is approximately three times faster in comparison with other wastes [10]. The amount of e-waste is estimated to reach 52 million tonnes or 6.8 kg per capita in 2021. However, around 20% of all e-waste generated is officially collected and recycled [11]. For example, the average lifespan of a new computer in India has reduced from seven years to four years [12]. Most e-waste was generated in Asia (16 million tonnes) whereas the least e-waste generation (0.6 million tonnes) was in Australia in 2016. The highest e-waste per resident (15.6 kg per capita) was in Europe, while Africa produced the lowest quantity of e-waste per capita (1.7 kg per capita). Both North and South Americas released around 11.7 million tonnes, which was equal to 12.2 kg per capita [13]. E-waste has no standard definition but, in general, e-waste refers to all types of electrical and electronic products and its components that have been discarded by the owner as waste without the intention of re-use [14]. E-waste can be divided into six main categories: large devices, small devices,small IT and telecommunications equipment, temperature exchange equipment, lamps, and screens and monitors. According to the information of [11; 13], Table 1 presents the examples of these categories and the amount of each category generated. Each category has different functions, and materials used, which causes various influences on the environment and human health if they are not strictly managed and treated. E-waste contains a wide range of valuable substances such as gold, platinum, silver, zinc, copper, plastic and palladium, which can be recycled to become potential new raw materials [11]. The total value of all raw materials contained e-waste is approximately 55 billion euros in 2016, which is higher than the 2016 Gross Domestic Product of most countries in the world [11]. For example, the highest average value comes from three valuable metals (platinum: 37,607 \(\upcels/\)kg; gold: 34,070 \(\upcels/\)kg; and palladium: \(\upcels/\)kg) [15]. However, e-waste also includes a large number of dangerous substances like lead (Pb), hexavalent chromium (Cr6), mercury (Hg), cadmium (Cd), and flame retardants (i.e., polybrominated biphenyls and polybrominated diphenyllethers) [16]. These chemicals assorted with solid wastes are posing a great risk for environmental deterioration especially in developing nations, like China and Bangladesh, where the appropriate technology for recycling is limited and non-formal recyclers are handling precious metals through crude ways due to an economic aspect [17]. Transboundary shipment of e-waste is strictly regulated by the Basel Convention. The developed countries have been banned the export of e-waste to developing countries. Unlawful activities are going leading to severe damage on health and the environment in some developing countries. With the lack of suitable treatment strategies, a large amount of e-waste ends up in landfills, leading to dangerous impacts on the environment and society [18]. There are many regulations developed and implemented by different governments and non-government organizations worldwide to prevent the growth and illegal movements of the e-waste between nations and, hence, restrict the pollution generated. In the European Union, there are two directives in e-waste handling, namely the Waste Electronic and Electrical Equipment (WEEE) directive and Restriction of Hazardous Substances (RoHS). The recycling rate of e-waste in the European Union is around 35% higher than the e-waste recycling rate in the US since the management of e-waste in the EU is implemented by these two directives [19].