PHYTODEGRADATION
Process Description
Phytodegradation is also called “phytotransformation”, this is a process wherein the
organic pollutants or contaminants in the soil, sediments, sludges, ground water, or surface water
by enzymes produced and released by the plant are degraded through metabolism within the
plant tissue or the external to the plant by the excretion of enzymes by the plant. These pollutants
were transformed into simpler molecules and are fused into the plant tissues as nutrients to help
the plants grow faster and bigger. Rapid chemical reactions occur inside the plant because they
contain enzymes and proteins. Example of these enzymes are nitroreductases, dehalogenases,
laccases, and etc.
Figure 1. Destruction of Organic contaminants by Phytodegradation.
Contaminants subject to phytodegradation include organic compounds such as munitions,
chlorinated solvents, herbicides, insecticides, and inorganic nutrients. For phytodegradation to
occur within the plant, the plant must be able to take up the compound. Phytodegradation is
considered as the most effective method in large areas that have comparatively low
contamination or pollution. Tree roots can be effectively remediated if it is within the
groundwater. As well as that groundwater that is used for irrigation.
Moreover, for the degradation to occur, it is highly dependent on the concentration,
solubility, hydrophobicity, and polarity of the contaminant which is also necessary for the
approval of contaminants by the plant. Also, the transpiration rate and its uptake efficiency. The
most available to be taken up by the plant tissue are the organic pollutants which has moderate
hydrophobicity and eventually, it is efficiently removed. Some examples of phytodegradation are
the following. Poplar metabolism of atrazine, alfalfa degradation of TCE and TCA through
exudates that stimulated bacteria, legumes, loblolly pine, and soybeans mineralization of TCE,
reduction of chlorinated phenols in wastewater, and minced horseradish roots treatment of 2,4-
dichlorophenol contaminated wastewater.
Phytodegradation Process Flow Diagram
Figure 2. Phytodegradation Process. This depicts the phytodegradation process in trees.
Source: ITRC (2001)
Advantages of Phytodegradation
Can be engaged to remediate sites that are polluted with organic compounds.
Can be used to remove contaminants/pollutants from industrial sites and storage areas,
fuel spills, and landfill leachates.
Certain enzymes produced by plants are able to degrade and transform chlorinated
solvents (e.g., trichloroethylene), herbicides, and ammunition wastes.
The transformed compounds that accumulate within the plant be non-toxic or
significantly less toxic than the parent compounds.
May be used as a polishing treatment.
Disadvantages of Phytodegradation
Contaminants can still enter the food chain through insects and animals that eat plants.
Soil alterations may be required, including chelating agents to facilitate plant uptake by
breaking bonds binding contaminants to soil particles.
Requires more than one growing season to be effective.
Soil must be less than 3 ft in depth and groundwater within 10 ft of the surface.
Cost of the Method
Estimated cost for the phytodegradation system using hybrid poplar trees is described in the
table. a five-year operation to remediate nitrate-contaminated groundwater.
Table 1. A five-year operation to remediate nitrate-contaminated groundwater.
(Source: Gatliff, E.G., 1996, Phytoremediation, Groundwater
Monitoring Review, Winter 1996.)
Design and Implementation $ 50,000
Monitoring Equipment:
Capital $ 10,000
Installation $ 10,000
Replacement $ 5,000
Five-year Monitoring:
Travel and Administration $ 50,000
Data Collection $ 50,000
Reports (Annual) $ 25,000
Sample Analysis $ 50,000
TOTAL $ 250,000
References:
A Citizen's Guide to Phytoremediation. (1998, August). Welcome to Sems
Publishing. https://semspub.epa.gov/work/05/142923.pdf
Longley, K. (2007, June). The feasibility of poplars for PHYTOREMEDIATION of TCE
contaminated groundwater: A cost-effective and natural alternative means of
groundwater treatment.
ResearchGate. https://www.researchgate.net/publication/265191596_THE_FEASIBILIT
Y_OF_POPLARS_FOR_PHYTOREMEDIATION_OF_TCE_CONTAMINATED_GR
OUNDWATER_A_Cost-
Effective_And_Natural_Alternative_Means_Of_Groundwater_Treatment
Phytodegradation potential of bisphenolA from aqueous solution by azolla Filiculoides. (n.d.).
Journal of Environmental Health Science and
Engineering. https://link.springer.com/article/10.1186/2052-336X-12-66
Phytoremediation of soils contaminated with metals and metalloids at mining areas: Potential
of native flora. (2014, March 26). IntechOpen - Open Science Open Minds |
IntechOpen. https://www.intechopen.com/books/environmental-risk-assessment-of-soil-
contamination/phytoremediation-of-soils-contaminated-with-metals-and-metalloids-at-
mining-areas-potential-of-nativ
Phytoremediation Resource Guide. (1999, June). United States Environmental Protection
Agency | US EPA. https://www.epa.gov/sites/production/files/2015-
04/documents/phytoresgude.pdf
Phytoremediation Resource Guide. (1999, June). United States Environmental Protection
Agency | US EPA. https://www.epa.gov/sites/production/files/2015-
04/documents/phytoresgude.pdf
Phytotransformation. (n.d.). University of Hawaii System | 10 campuses across the Hawaiian
Islands. https://www.hawaii.edu/abrp/Technologies/phytran.html
Pivetz, B. E. (2001, February). Phytoremediation of Contaminated Soil and Ground Water at
Hazardous Waste Sites. United States Environmental Protection Agency | US
EPA. https://www.epa.gov/sites/production/files/2015-
06/documents/epa_540_s01_500.pdf
