In 2020, Lausanne’s soil was contaminated with dioxins from manufacturing processes. Cleaning is expensive and time-consuming, leaving officials unsure whether to proceed.
EPFL scientists are developing sustainable soil remediation methods, like bioremediation, which uses microorganisms to break down pollutants.
Christof Holliger, head of EPFL’s Environmental Biotechnology Laboratory, compares this process to how our bodies convert pasta into glucose for energy.
Holliger’s team has been working on bioremediation, specifically using bacteria to eliminate contaminants from chlorinated solvents. These solvents are a major pollutant in Switzerland’s soil and water.
The researchers have found bacteria that can “inhale” these compounds and convert them into harmless substances using a process called halo respiration. This process involves proteins like reductive dehalogenase, which breaks the contaminant bonds.
These bacteria have adapted over time to thrive on chlorinated compounds, using energy from hydrogen other bacteria produce through fermentation. This intricate system of bacteria simultaneously helps break down the pollutants.
This natural process can only work in specific conditions. The contaminant must be in high concentration; otherwise, it competes with other organic compounds. Multiple bacteria types in precise amounts are needed for halo respiration, making it impossible to cultivate a kind in the lab and add it to the soil. Also, several pollutants in the contaminated soil further complicate the process.
In the right conditions, bioremediation is practical. Scientists do not disturb the bacteria in soil or water but create optimal conditions for them to thrive. For example, at a hydrocarbon-contaminated site, soil with high carbon needs enrichment with nitrogen and phosphorus for bacterial development.
Despite its limitations, bioremediation is widely used to clean hydrocarbon spills and contaminated water tables managed by specialized firms. Famous cases include the Exxon Valdez oil spill in Alaska.
Source: Tech Explorist
