Heavy metals are highly soluble in water and non-biodegradable, and tend to persist indefinitely when released. Lead (Pb) is one of the most widely used heavy metals. Its production increased by around 20% over the last decade, reaching around 11.7 million tons globally in 2020. It is highly toxic, even in low concentrations, with harmful effects on the organs and tissues of the human body.
The biosorption of heavy metals, including lead, has been heavily studied by science. Now, new research by specialists from the Massachusetts Institute of Technology (MIT) found that yeast, a plentiful waste product in breweries, can leach out even small amounts of lead.
The MIT researchers mention in their Flint analysis, the water crisis in Michigan, United States, in 2014, where the city’s water source was changed from a lake to a river and lead leaked out of aging pipes. Their findings have just been published in a journal article Nature Communications Earth and Environment .
The solution studied by the MIT team, called biosorption, has been known for decades. But the process has only been examined at higher concentrations, at the one part per million level. MIT says its research shows the approach can dent pollution levels of one part per billion. The allowable standard for lead is 5 parts per billion in the European Union, while the US Environmental Protection Agency says that no level of lead in water supplies is safe.
Biosorption uses inactive biological material to remove heavy metals from water. The MIT team reportedly “showed that a single gram of dry, inactive yeast cells can remove up to 12 milligrams of lead in aqueous solutions with initial lead concentrations below 1 part per million” in just five minutes. “This work reports this index for the first time,” he said. Patritsia M. Stathatouone of the main authors of the research and specialist of the Center of Bits and Atoms from MIT.
“Exploiting yeast as a biosorbent may be practically feasible and economically attractive. Yeast can be easily grown in large quantities, while also having a number of beneficial industrial applications, including those related to the production of food, beverages, therapeutics and biofuels,” Stathatou said.
The global fermentation industry uses three million tons of yeast per year, while the yeast market is expected to grow 35% in the next 5 years. “However, the sugars and proteins necessary for yeast growth are derived from food crops and sources that could be used for human nutrition,” the scientist continued. “Therefore, to avoid compromising food safety, residual or surplus yeast from fermentation industries would be a more sustainable option for large-scale application of this water purification approach. In fact, surplus yeast is currently produced in large volumes and is an extremely underutilized, low-value resource, not suitable as a human dietary supplement due to high levels of nucleic acids.”
This process cannot yet be launched openly onto the market because, as the specialists warn in their document, It would be necessary to design a system to process the water and recover the yeast, embedding its cells in a kind of filter. MIT is working on it. In addition to lead, the method It can also be used to remove heavy metals such as cadmium and copper. “In general, this work shows the use of an effective biomaterial for the removal of traces of heavy metals, made from a microorganism that is respectful of the environment, economical, benign for human health and easy to mass produce,” concluded the specialist. .