Engineering Science

Zero-emission technology for E-waste management

The methodology is a three-step process which involves pyrolysis of e-waste, separation of metal fraction, and recovery of individual metals

April 16, 2021
The Scitech

Led by Professor K.K. Pant, his research group in the Catalytic Reaction Engineering Laboratory at Chemical Engineering Department, Indian Institutes of Technology (IIT) Delhi, has developed a sustainable technology to tackle the menace of e-waste. The adopted methodology is a three-step process which involves pyrolysis of e-waste, separation of metal fraction, and recovery of individual metals. The developed technology will cater to the need of “Smart Cities,” “Swachh Bharat Abhiyan,” and “Atmanirbhar Bharat” initiatives of the Indian government via waste to wealth generation in decentralized units, researchers said.

e-waste is shredded and pyrolyzed to yield liquid and gaseous fuels, leaving behind a metal-rich solid fraction. On further separation using a novel technique, the leftover solid residue yields a 90-95% pure metal mixture and some carbonaceous materials. The carbonaceous material is further converted to aerogel for oil spillage cleaning, dye removal, carbon dioxide capture, and use in supercapacitors. In the next step, a low-temperature roasting technique is employed to recover individual metals such as copper, nickel, lead, zinc, silver and gold from the metal mixture. It gives a recovery of nearly 93% copper, 100% nickel, 100% zinc, 100% lead, and 50% gold and silver each. It is a green process in which no toxic chemicals are released into the environment.

The research team has successfully installed a 10 kg/h (Kilogram per hour) pyrolysis plant for e-waste recycling at IIT Delhi. It converts all types of e-waste to combustible gases of 28 MJ/kg (Megajoule per Kilogram) calorific value, liquid fuel of 30 MJ/kg calorific value, and a metal-rich solid residue. The gaseous product obtained from the pilot plant is primarily composed of hydrogen and methane whereas the liquid product is rich in hydrocarbons suitable for energy generation. The pilot plant is also equipped with a scrubbing system that captures halogenated compounds traces in the combustible gases.

Prof. K.K. Pant, Project Lead and Head of Chemical Engineering Department, IIT Delhi said, “The developed technology can be employed for recycling all types of e-waste as well as plastic waste, and it does not emit any toxic chemicals to the environment. Besides providing a sustainable solution for e-waste recycling, successful implementation of this technology has the potential to generate large number of jobs in the waste recycling industry.” The technology has also been patented and published in internationally reputed journals such as the Journal of Cleaner Production, Journal of Hazardous Materials, Waste Management and the Journal of Environmental Chemical Engineering.

Source: India Science Wire