Public Services and Procurement Canada
Anaerobic bioremediation is an in situ technology applicable for soil or groundwater contaminated with petroleum hydrocarbons or other organic contaminants in saturated conditions.
This technology consists of providing all the necessary compounds (electron acceptor, nutrients, substrate, etc.) to stimulate the indigenous anaerobic microorganisms (strict or facultative) to enhance contaminant biodegradation. Strict anaerobic microorganisms cannot use oxygen as the final electron acceptor in the respiratory chain and therefore, they use alternative electron acceptors such as nitrate (NO3-), dissolved manganese (Mn4+), ferric iron (Fe3+), sulfate (SO42-) and carbon dioxide (CO2). Alternative electron acceptors are more water-soluble than oxygen and can be more easily injected into the dissolved phase. Nutrients may be injected in a dissolved (such as commercial soluble fertilizer), or gaseous form. Addition of a substrate can help reduce the oxygen concentration and establishing anaerobic conditions.
Anaerobic bioremediation has seen extensive application for the remediation of chlorinated solvents contaminated sites. Anaerobic biodegradation of chlorinated organic compounds is discussed in the Reductive Dechlorination technology sheet.
In addition to the chlorinated compounds, in situ anaerobic bioremediation treatment has been demonstrated for multiple contaminants including petroleum hydrocarbons, ammonium, nitrate, sulfate, pesticides, explosives and dioxins. Depending on the contaminant and on the geochemistry of the contaminated media, practitioners may inject food-grade oils, hydrogen sources, nitrates, fertilizers, etc.
Contaminants are degraded or transformed by the bacteria and the treatment is complete when the contaminant concentrations have reached the treatment objectives.
Issues with anaerobic bioremediation include the distribution of components required by the treatment in the subsurface and ensuring adequate environment for optimal microbial growth.
Tests examining the effect of temperature change on hydraulic conductivity and
establishing the zone of freezing with a pilot scale tubing system are recommended to
properly design the full-scale containment system.
In situ anaerobic bioremediation is potentially applicable to remote northern sites where impediments to material transport and injection equipment mobilization can be overcome. Cold temperatures can hamper biodegradation and microbial activity may only occur during the summer months, thus treatment time may take several years. Microbial activity may be possible in deep soil as temperatures (below permafrost) are relatively constant over the course of the year.
Follow-up monitoring may be required to verify that the groundwater system normalizes and the applicable regulations are met after the stimulation is withdrawn and excess biomass dies off.
Application examples are available at these links:
The treatment time for complete remediation using anaerobic bioremediation varies according to the type and concentration of contaminants, the indigenous microbial population and the physical and chemical conditions of the contaminated site.
Unavailable for this fact sheet
Composed by : Karine Drouin, M.Sc., National Research Council
Updated by : Karine Drouin, M.Sc., National Research Council
Updated Date : April 1, 2008
Latest update provided by : Marianne Brien, P.Eng., Christian Gosselin, P.Eng., M.Eng., Golder Associés Ltée
Updated Date : March 22, 2019