The International Information Center for Geotechnical Engineers

Bioremediation - Applicability to Soil and Contaminant Types

Applicability to Soil and Contaminant Types 

 

Like all remediation methods, bioremediation is best suited for certain types of contamination and certain types of soils.

Applicability to contaminants

Organic:

Bioremediation is excellent for biodegrading organic contaminants. Common types of organic contaminant that respond well to bioremediation include: petroleum hydrocarbons, non-chlorinated chemicals (e.g. acetone), wood treating chemicals (e.g. creosote and pentachlorophenol (PCP)), certain chlorinated aromatic compounds (e.g. chlorobenzenes and biphenyls with five or fewer chlorine atoms per molecule) and certain chlorinated aliphatic compounds (e.g. tricholoroethene (TCE)) (USEPA, 2001a).

Bioremediation methods can be implemented to tackle organic contaminants in three key ways (Sharma & Reddy, 2004):

1. Destruction of the organic contaminant.

2. Oxidation of organic contaminants to create products of smaller molecular weight and lower toxicity.

3. Dehalogenation of organic contaminants.

Here destruction of organic contaminants is taken to mean the physiological process by which microorganisms bond with contaminants through oxidation and reduction reactions, the energy released in these reactions provide energy for the microorganism (Sharma & Reddy, 2004). Organic contaminants such as hydrocarbons acts as electron donors in these reactions (aerobic), whereas other common contaminants such as chlorinated solvents can act an electron acceptors (anaerobic).

When applied to waste the suitability of biodegredation techniques for particular types of waste can be assessed by following relevant ASTM standards. For example the biodegradation of plastics in soil and in bioreactor landfills can determined by following ASTM D5988 (Standard Test Method for Determining Aerobic Biodegredation of Plastic Materials in Soil) and ASTM D7474 (Standard Test Method for Determining Aerobic and Anaerobic Biodegredation of Plastic Materials under Accelerated Bioreactor Landfill conditions), respectively.

Inorganic:

Inorganic contaminants such as heavy metals from AMD are often treated using bioremediation techniques. Bioremediation can in some cases change the valence state of heavy metals and render it immobile e.g. mobile hexavalent chromium to immobile trivalent chromium.

 

Applicability to soils and groundwater

Soil treatment:

Almost all contaminated soils with moisture content able to support microbial life are suitable for treatment for using bioremediation. However, soils of low permeability can be difficult when trying to get amendments to permeate throughout the contaminated soil mass (Sharma & Reddy, 2004). If the contaminant concentration is very high, the conditions may be too toxic for microorganisms to survive making bioremediation ineffective.

Groundwater treatment:

Homogenous soils with hydraulic conductivity, k, equal to 10-4 cm/s or greater are suitable for treatment with bioremediation (Sharma & Reddy, 2004). If the hydraulic conductivity is too low adding amendments and removing products from the soil may be difficult. Bioremediation can be used to treat Dense Non-Aqueous Phase Liquids (DNAPLs). It is also ideal for treating single sources and as a follow up treatment after free-product removal by a different method.

Add comment

NOTE: The symbol < is not allowed in comments. If you use it, the comment will not be published correctly.

Security code
Refresh
*Please insert the above-shown characters in the field below.

The Geoengineer.org Corporate Sponsors: