PhytoremediatioPhytoremediationn

Debbie SchuttenhelmDebbie Schuttenhelm

ChE 562ChE 562

11/17/0411/17/04

OutlineOutline

What is phytoremediationWhat is phytoremediation Types and examplesTypes and examples Other removal methodsOther removal methods ProsPros ConsCons

What is What is phytoremediation?phytoremediation?

Using living plants for contaminant Using living plants for contaminant removal, degradation, or containmentremoval, degradation, or containment

Clean up soil and or groundwaterClean up soil and or groundwater Can remove organics, metals, leftover Can remove organics, metals, leftover

pesticides, explosives, radioactive pesticides, explosives, radioactive wastewaste

Used independently or with other Used independently or with other cleanup methods to reduce costscleanup methods to reduce costs

TypesTypes

PhytoextractionPhytoextraction Uptake by plants and accumulation in Uptake by plants and accumulation in

leaves or stemleaves or stem PhytodegradationPhytodegradation

Plants metabolize contaminantsPlants metabolize contaminants RhizodegradationRhizodegradation

Plants promote microbial activity that Plants promote microbial activity that breaks down contaminantsbreaks down contaminants

PhytovolatilizationPhytovolatilization Uptake and transpirationUptake and transpiration

OverviewOverview

MechanismsMechanisms

http://www.itrcweb.org/PHYTO2.pdfhttp://www.itrcweb.org/PHYTO2.pdf

PhytoextractionPhytoextraction Metal hyperaccumulators - Alpine Metal hyperaccumulators - Alpine

pennycresspennycress Concentrate zinc, cadmium, nickel in stems and Concentrate zinc, cadmium, nickel in stems and

leavesleaves Takes in 30,000ppm zinc and 1,500ppm cadmium Takes in 30,000ppm zinc and 1,500ppm cadmium

as opposed to 100ppm and 1ppm, respectivelyas opposed to 100ppm and 1ppm, respectively 30 times as much as usually poisons other plants30 times as much as usually poisons other plants Harvested and burned, ashes sold as high-grade Harvested and burned, ashes sold as high-grade

zinc orezinc ore Also research in adding citrate to soil to make Also research in adding citrate to soil to make

uranium more soluble for 100 times higher uranium more soluble for 100 times higher uptakeuptake

MechanismMechanism

Phyto/RhizodegradationPhyto/Rhizodegradation

Poplar treesPoplar trees Can uptake and metabolize atrazine Can uptake and metabolize atrazine

(toxic herbicide) in soil(toxic herbicide) in soil Also stimulates microbes in soil to Also stimulates microbes in soil to

further degrade contaminantsfurther degrade contaminants Enzyme nitroreductase can break down Enzyme nitroreductase can break down

TNTTNT Saplings bring levels below detectable Saplings bring levels below detectable

limits within a few weekslimits within a few weeks

PhytovolitalizationPhytovolitalization

Indian mustardIndian mustard Take up selenium from the soil, Take up selenium from the soil,

contaminant around oil wells, power contaminant around oil wells, power plants, and mining operationsplants, and mining operations

Convert to dimethyl selenide and Convert to dimethyl selenide and release to atmosphererelease to atmosphere

Less desirable process because Less desirable process because atmospheric effects generally unknownatmospheric effects generally unknown

Continuing researchContinuing research

MTBE – poplar and eucalyptus MTBE – poplar and eucalyptus saplingssaplings

Perchlorate – willows and cedarsPerchlorate – willows and cedars Arsenic – fernsArsenic – ferns Depleted uranium – tumbleweedsDepleted uranium – tumbleweeds DDT – pumpkinsDDT – pumpkins

Other methods of Other methods of removalremoval

Removal and landfilling of Removal and landfilling of contaminated soilcontaminated soil

Incineration of contaminantsIncineration of contaminants Surfactants used to wash Surfactants used to wash

contaminants out of soilcontaminants out of soil Ion exchange, reverse osmosis, other Ion exchange, reverse osmosis, other

methods in contaminated methods in contaminated groundwatergroundwater

Pros of PhytoremediationPros of Phytoremediation

Reduction in landfill volumeReduction in landfill volume 30 tons of ash vs. 5,000 tons soil for 2.5 30 tons of ash vs. 5,000 tons soil for 2.5

acre site, 18in deepacre site, 18in deep Low maintenanceLow maintenance Positive public opinionPositive public opinion Cost benefitsCost benefits

Cost benefitsCost benefits

Costs – water cleanupCosts – water cleanup

http://www.dtsc.ca.gov/ScienceTechnology/http://www.dtsc.ca.gov/ScienceTechnology/TD_REP_Perchlorate-Alternatives.pdfTD_REP_Perchlorate-Alternatives.pdf

ConsCons

Much slower to implement, seasonal Much slower to implement, seasonal processprocess

Not as effective with very high Not as effective with very high concentrationsconcentrations

Limited by root depthLimited by root depth Toxicity of biodegradation products Toxicity of biodegradation products

not always knownnot always known Possibility of contaminants entering Possibility of contaminants entering

food chainfood chain

ReferencesReferences http://www.ars.usda.gov/is/AR/archive/junhttp://www.ars.usda.gov/is/AR/archive/jun

00/soil0600.htm00/soil0600.htm http://ehp.niehs.nih.gov/docs/1995/103-12http://ehp.niehs.nih.gov/docs/1995/103-12

/innovations.html/innovations.html http://www.itrcweb.org/PHYTO2.pdfhttp://www.itrcweb.org/PHYTO2.pdf http://www.epa.gov/tio/download/remed/phttp://www.epa.gov/tio/download/remed/p

hytoresgude.pdfhytoresgude.pdf http://csmonitor.com/2004/0415/p17s02-sthttp://csmonitor.com/2004/0415/p17s02-st

en.htmlen.html