Introduction
The demand for electronic equipment has increased dramatically all over the world. Newer electrical and electronic inventions are a constant source of attraction for consumers. Consequently, the ‘lifespan’ of existing equipments has shortened. A side effect of this phenomenon is that the amount of waste being generated from discarded electrical and electronic components is increasing day by day. Currently, by some estimates, 20 to 25 million tons of e-waste are being generated in the world every year. Most of this is inadequately disposed in landfills. This amount is much higher than the projections made just a decade ago. Not only is this waste choking the Earth’s ecosystem, it also poses significant threats to human health and longevity.
In general, e-waste is often hazardous and needs to be managed and disposed of properly. However the presence of precious metals in e-waste including gold, silver, platinum and gallium makes recycling a more attractive proposition than disposal. In fact, dumped e-waste is estimated to contain over $60 million in gold and silver. Furthermore, for every 1 million cell phones that are recycled, the amounts of precious metals that can be recovered are:
- 16,000kg of copper
- 350kg of silver
- 34kg of gold
- 15kg of palladium.
For all these reasons, approximately 12.5% of e-waste is currently being recycled all over the world.
E-waste: Threats to human life
The health risks associated with e-waste often result from direct contact with harmful materials contained in them or through inhalation of toxic fumes. These materials include lead, cadmium, chromium, brominated flame retardants and polychlorinated biphenyls (PCBs). These harmful materials dissolve in soil and water, and enter the food chain, which has a dangerous effect on human health, often leading to illness, disability and even death.
Practical ways to extract metals from e-waste and minimise their environmental impact
Here are some practical ways to tackle the problem of e-waste-
Gold Extraction by acid treatment
A combination of hydrochloric acid and nitric acid is used to extract gold from e-waste. Other mild acids are also occasionally used The acid mix can successfully dissolve gold while limiting the potential of the e-waste to cause adverse effect to the environment.
Bioleaching
Microbiological processes have been proposed over the last decade as a possible alternative to extract precious metal such as copper, gold, palladium and silver from e-waste. Bacteria such as Thiobacillus ferrrooidans and T.thiooxidans,as well as fungi including asperillus Niger and penicillum simplicissimum have been used to successfully extract copper , aluminium and zinc from e-waste. The most hazardous metals like lead can also be extracted from e-waste with the bioleaching process of metal extraction.
Advantage of Metal Extraction
These extraction processes not only extract metal from e-waste but also reduce the amount of waste that are dumped carelessly into landfills all over the world (which adversely affects land fertility). By extracting precious metals from e-waste, their mining can be controlled. Furthermore, this reduces carbon emission and helps arrest the other harsh environmental consequences of precious metal mining.
Conclusion
Proper e-waste management will help with the efficient sourcing, collection, extraction and disposal of materials. This will help convert the huge mountains of e-waste currently generated into more useful products. It will also create new business opportunities that will benefit the global economy
7. REFRENCES:-
Web sites:-
3. https://green.harvard.edu/tools-resources/how/6-ways-minimize-your-e-waste
4. https://www.teriin.org/article/e-waste-management-india-challenges-and-opportunities
Written by
Rushiraj Kantilal Jadhav