Biological remediation of a contaminated area

Biological remediation methods for contaminated soil or groundwater in brief:

  • implementation without excavating soil and transferring groundwater (in-situ)
  • create optimal conditions for microbial activity (pH, temperature, humidity)
  • hazardous substances are degraded or transformed into a harmless state by microbial activity
  • suitable for organic compounds, such as hydrocarbons, solvents, pesticides
  • long-term remediation methods.

In biological remediation methods, the degradation and transformation of contaminants is based on biological processes that occur under the influence of microbes. In biological methods, optimal conditions are created for microbes so that they can use hazardous substances as food and energy sources. Typically, this means adding nutrients and oxygen and optimising the pH, temperature and humidity to promote microbial growth.

Biological methods are suitable for organic pollutants, such as hydrocarbons, organic solvents and pesticides. In most cases, the methods are not suitable for inorganic compounds, but the absorption of hazardous substances in plants is also suitable for inorganic pollutants, such as heavy metals.

Biological remediation can take a relatively long period of time. However, the costs are often low and local disturbances are minor, especially with in-situ methods.

Wide array of biological methods

In its simplest form, biological remediation means that contaminant levels are decreased as a result of naturally occurring biological processes. In this case, microorganisms, such as bacteria and enzymes, break down hazardous substances. Natural biodegradation, which is combined with environmental monitoring, is called monitored inherent biodegradation, which is often the most environmentally- and cost-effective risk management method.

Natural biodegradation can be enhanced by adding nutrients and reagents as well as oxygen to soil in order to promote the activity of microorganisms. This refers to enhanced biological remediation, which can be conducted in aerobic or anaerobic conditions. Enhanced biological remediation can be conducted either with the in-situ method or by excavating soil.

Phytoremediation uses plants or fungi and microbes living in symbiosis with them to remediate contaminated soil or groundwater. Plants can absorb hazardous substances and stabilise or degrade them. The method is suitable for both organic and inorganic contaminants.