Electronic waste generation, regulation and metal recovery: a review

Abstract

Waste will become the major resource in the future circular economy. In particular, E-waste is a major sector growing at an annual rate of about 2 million tonnes (Mt) with rising users of electrical and electronic items worldwide. This is a consequence of versatility and affordability of technological innovation, thus resulting in massive sales and e-waste increases. Most end-users lack knowledge on proper recycling or reuse, often disposing of e-waste as domestic waste. Such improper disposals are threatening life and ecosystems because e-waste is rich in toxic metals and other pollutants. Here we review e-waste generation, policies and recycling methods. In 2019, the world e-waste production reached 53.6 Mt, including 24.9 Mt in Asia, 13.1 Mt in USA, 12 Mt in Europe. In Asia, China (10.1 Mt), India (3.23 Mt), Japan (2.57 Mt) and Indonesia (1.62 Mt) are the largest producers contributing to about 70% of the total world e-waste generated. Only 17.4% (9.3 Mt) of the world e-waste was recycled by formal means, and the remaining 82.6% (44.3 Mt) was left untreated or processed informally. As a consequence, most countries have framed policies to provide regulatory guidelines to producers, end-users and recyclers. Yet the efficiency of these local policies are limited by the transfer of products across borders in a globalized world. Among formal recycling techniques, biohydrometallurgy appears most promising compared to pyrometallurgy and hydrometallurgy, because biohydrometallurgy overcomes limitations such as poor yield, high capital cost, toxic chemicals, release of toxic gases and secondary waste generation. Challenges include consumer’s contempt on e-waste disposal, the deficit of recycling firms and technology barriers.