Scientists at Coventry University in England have discovered that it is possible to use bacteria in the process of recycling electric vehicle batteries. They used a system known as bioleaching to extract the valuable metals from the lithium-ion energy cells that power automobiles.
This natural process for extracting metals has been used by the mining industry for a long time. The technique is also used to clean and recover materials found in electronic waste, such as printed circuit boards, solar panels, and water contaminated by lead and uranium.
The process, also called biomining, uses microbes that can oxidize metals as part of their metabolism. “This method is very effective and ecologically correct, as it does not harm the environment during the metal extraction phases”, explains the professor of molecular biology from Coventry University, Sebastien Farnaud, lead author of the study.
The researchers used bacteria such as Acidithiobacillus ferrooxidans and other non-toxic species to obtain energy from the oxidation of ferrous ions, promoting the solubilization of various metals such as copper and zinc. This metallic material resulting from the extraction process has chemical elements that can be recycled in various production chains.
During the bioleaching process, bacteria grow in incubators at 37ºC, using carbon dioxide as fuel. As this system uses a very small amount of energy, the carbon footprint generated is infinitely smaller than that produced by conventional recycling plants.
By combining bioleaching with electrochemical methods, scientists were able to remove the most valuable metals from electronic waste and keep them floating in an aqueous solution so they could be easily “fished” and reused in other industrial processes.
Recycle is necessary
Most of the metal is extracted by melting power cells in large power plants that consume a lot of electricity and emit a very high amount of carbon. The factories that carry out this process, most of them in China, are expensive to build and require sophisticated equipment to deal with the pollutant emissions generated during the battery casting process. Even so, not all of the most valuable materials in energy cells can be recovered and returned to the environment.
Batteries currently used in electric cars have a useful life ranging from eight to ten years. These lithium-ion cells are already recycled, but the percentage is still very low and this process manages to recover only 5% of all the material used in the construction of energy storage devices.
It is estimated that the global metal recycling market is expected to grow from US$52 billion (about R$260 billion) in 2020 to just over US$76 billion (approximately R$380 billion in direct conversion) in 2025. Therefore, it is necessary to review the concepts used in reuse systems that consume excess energy and aggravate environmental problems.
“Instead of being in the background, with bioleaching recycling can become both the beginning and the end of a battery’s life cycle in electric vehicles, producing high-quality raw materials for the manufacture of new energy cells with low environmental cost”, concludes Farnaud.
Source: The Conversation