Fact sheet: Mycoremediation: white rot fungus

From: Public Services and Procurement Canada

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Description

The use of white rot fungus for remediation technology is an ex situ or in situ remediation used for the treatment of residual organic compound contamination. White rot fungus produces extracellular peroxidases and laccases enzymes to degrade lignin and these enzymes are able to catalyze the degradative attack on a variety of organic contaminants such as conventional explosives, semi-volatile organic compounds (SVOCs) and other recalcitrant contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and pentachlorophenol (PCP).

This technique consists of mixing contaminated soil with the white rot fungus and a substrate, such as woodchips, to stimulate the development of the fungus and to promote soil aeration. This technique is similar to composting but inoculation with the white rot fungus is necessary. Several factors affect the performance of this technique including, nitrogen and oxygen concentrations, potential of hydrogen (pH), humidity and temperature.

In Canada, the introduction of microbial strains into the environment is regulated under the New Substances Notification Regulations (NSNR) of the Canadian Environment Protection Act, 1999. Microorganisms must be on the Domestic Substances List (DSL) compiled by Environment Canada in order to be used in remediation procedures.

Sources:

Recommended analyses for detailed characterization

Biological analysis

  • Total heterotrophic and specific bacterial counts (according to the contaminants of interest)

Chemical analysis

  • Contaminant concentrations:
    • identification and concentration of all contaminants (sorbed, dissolved, and free phase)
  • pH
  • Nutrient concentrations includes:
    • lammonia nitrogen
    • total Kjeldahl nitrogen
    • nitrates
    • nitrites
  • Metals concentrations

Physical analysis

  • Vadose zone oxygen, nitrogen dioxide, and methane concentrations
  • Temperature
  • Soil water content
  • Evaluation of biological conditions and ecological factors

Recommended trials for detailed characterization

Biological trials

  • Microcosm mineralization trial
  • Biodegradation trial

Physical trials

  • Evaluation of optimal mixing rates

Other information recommended for detailed characterization

Phase II

  • Contaminant delineation (area and depth)
  • Presence of receptors:
    • presence of potential environmental receptors
    • presence of above and below ground infrastructure
    • the risk of off-site migration

Phase III

  • Soil stratigraphy
  • Characterization of the hydrogeological system includes:
    • the depth and thickness of the aquifer
    • the direction and speed of the groundwater flow
  • Identification of preferential pathways for contaminant migration
  • Conceptual site model with hydrogeological and geochemical inputs

Applications

  • Suitable for the treatment of residual contamination
  • Applies to organic contaminants that can be degraded or transformed under aerobic conditions
  • Optimal conditions for the technique are a potential of hydrogen (pH) between 4 and 5, humidity between 40 and 45%, and temperatures between 30 and 38 0C
  • In general, white rot fungus prefers an environment with low nitrogen content

Treatment type

Treatment typeApplies or Does not apply
In situ
Applies
Ex situ
Applies
Biological
Applies
Chemical
Does not exist
Control
Does not exist
Dissolved contamination
Does not exist
Free Phase
Does not exist
Physical
Does not exist
Residual contamination
Applies
Resorption
Applies
Thermal
Does not exist

State of technology

State of technologyExist or Does not exist
Testing
Exist
Commercialization
Exist

Target contaminants

Target contaminantsApplies, Does not apply or With restrictions
Aliphatic chlorinated hydrocarbons
Applies
Chlorobenzenes
Applies
Explosives
Applies
Metals
With restrictions
Monocyclic aromatic hydrocarbons
Applies
Non metalic inorganic compounds
Does not apply
Pesticides
Applies
Petroleum hydrocarbons
Applies
Phenolic compounds
Applies
Policyclic aromatic hydrocarbons
Applies
Polychlorinated biphenyls
Applies


Notes:

Metals are not degraded by this technology but accumulate in the fruiting bodies and should be collected regularly.

Treatment time

Treatment timeApplies or Does not apply
Less than 1 year
Applies
1 to 3 years
Applies
3 to 5 years
Does not apply
More than 5 years
Does not apply

Secondary by-products and/or metabolites

By-product and metabolite production during biodegradation or transformation with white rot fungus need to be analyzed to ensure that no production of compounds of greater concern than the parent compound are produced. Examples of compounds that are completely biodegraded by white rot fungus are available in the literature.

Limitations and Undesirable Effects of the Technology

  • High metal or contaminant concentrations can be toxic to the white rot fungus
  • Development and growth of white rot fungus was not observed below 10 0C
  • Competition between native bacterial populations can reduce the efficiency of the treatment
  • Soil mixing can interfere with the production of enzymes by the fungus
  • Fungi are susceptible to water stress
  • Little knowledge is available regarding the ability of white rot fungus to compete with other types of fungi

Complementary technologies that improve treatment effectiveness

  • Thermal treatment

Required secondary treatments

  • There is no secondary treatment required

Application examples

Application examples are available at this address:

Performance

It is important to verify whether white rot fungus technology meets the remediation objectives before applying this technique to a large volume of soil.

References

Author and update

Composed by : Magalie Turgeon, National Research Council

Latest update provided by : Jennifer Holdner, M.Sc., Public Works Government Services Canada

Updated Date : March 1, 2015

Date Modified: