Millions of people around the world live within 5 km of living in the vicinity of toxic landfills. This puts them at increased risk of cancer and other serious illnesses.
Although the decontamination of such sites is a public health priority in developed countries, there are many technical challenges in the process. The most problematic is a pair of chlorinated chemicals known as trichlorethylene (TCE) and perchlorate. TCE has been widely used as a degreasing agent, and perchlorate has been used in the production of propellants, injected under gas pressure. Due to the ubiquitous dependence of manufacturers on these chemicals in the past and their improper disposal, they often end up in the environment, posing a significant risk to human health and the surrounding ecosystems.
Biological treatment to remove these highly toxic chemicals, especially when present in mixtures, has long been a challenge for scientists. Chlorinated chemicals are capable of contaminating entire drinking water systems on which both animals and humans depend.
In a new study, experts from the Biodesign Swette Center for Environmental Biotechnology have explored new ways to rid the environment of these toxic chemicals. To do this, the scientists used elemental iron with zero valence (Fe0) in combination with the unusual microbe Dehalococcoides mccartyi. It was added to soil and groundwater samples from a contaminated toxic waste site in Goodyear, Arizona. Previously, the area was used in defense and aerospace production.
It turned out that the bacteria Dehalococcoides work in synergy with iron and effectively convert TCE and perchlorate into less toxic end-products of microbial biodegradation – for example, ethylene (C₂H₄)
The results of the study are paving the way for the use of microbes to combat chlorinated chemical pollution.