BZ572 - Phytoremediation

Elizabeth Pilon-Smits Biology Department E413 ANAZO

491-4991 [email protected]

Let’s hear from you

Please write on piece of paper:

• Degree, major/department, reg./auditing?

• What is your career goal?

• How does phytoremediation fit in?

• Any particular aspects of phytoremediation you are most interested in?

BZ572 – Course Info

Text:

webct No book, only papers from course website

Topics:

- Intro to phytoremediation - Phyto of inorganics*) - Phyto of organics*) - 1 Lab expt, 1 trip to a lab, 1 field trip (if interest), 5 guest lectures, in-class exercises, job info *) mechanisms of uptake, translocation, detoxification, effects of soil, microbes on remediation, approaches to enhance phyto efficiency, including genetic engineering

Grading: Conventional, no curving

Exams:

50% of total grade - 1 midterm + 1 final exam (not comprehensive) essay questions

Term paper & presentation:

30% of grade - write web page/proposal/review + present

In-class participation:

20% of grade - lab report, in-class group assignments, literature discussions

Introduction to Phytoremediation

• History • Status • Uses • Advantages • Limitations

• Phytoremediation strategies

History of phytoremediation

• for centuries: wetlands used for waste treatment in Europe • last century: metal hyperaccumulator plants discovered used as indicators for mining • 1970s: - clean water act, clean air act • 1980s: - superfund act (1986 - 8.5 billion $) - idea to use hyperaccumulator plants for metal cleanup (Chaney)

History of phytoremediation (cont.) • 1994: phytoremediation term coined (Ilya Raskin) massive interest from gov. & industry - DOE phytorem. workshop - first phytorem. company (Phytotech) • 1995: first phytorem. conference

phytoremediation takes off

History of phytoremediation (cont.) • •(Raskin) 1994: Term phytoremediation first used • 1995: First phyto conference Columbia MO • 2000: EPA phyto conference • 2000: 1 st phyto faculty positions • 2000: 1 st phyto course (this one) • 2001, 2003: 1 st , 2 nd • 2000, 2001: 1 st , 2 nd phyto call for proposals •(NSF/EPA/DOE) professors in phyto •(U Mich, U S-Carolina)

Status of phytoremediation

• U.S. phytoremediation market

(Glass, 1999, 2004 pers. comm.)

1999 $ 30 - 49 million / yr 2004 $ 100-150 million / yr • World phytoremediation market 1999 $ 34 - 58 million • Total remediation market US: $ 6-8 billion/yr World: $ 25-50 billion/yr

Status of phytoremediation (cont.) • 9 purely phytorem. companies • 7 constructed wetland companies • > 40 consulting/engin. companies that also do phytoremediation • ~200 field projects - funded mostly by EPA, DOD, DOE - some commercial/joint projects

Uses of phytoremediation

Remediation of different media: • air • soils, sediments • groundwater • wastewater streams - industrial - agricultural - municipal, sewage

• Uses of phytoremediation (cont.) Remediation of different pollutants: inorganics : - metals (Pb, Cd, Zn, Cr, Hg) - metalloids (Se, As) - “nutrients” (K, P, N, S) - radionuclides (Cs, U) • organics: - PCBs - PAHs - TCE - TNT - MTBE - pesticides - petroleum hydrocarbons

Etc.

Uses of phytoremediation (cont.) Remediation using different systems: • farming polluted soil • irrigation with polluted groundwater • letting trees tap into groundwater • letting plants filter water streams constructed wetlands, hydroponics

different systems:

Hydraulic barrier

• different systems:

Vegetative cap

different systems: • Constructed wetlands

different systems: hydroponics with polluted wastewater

Roots of mustard Extend into effluent Acting as filters for heavy metals

Uses of phytoremediation (cont.) Remediation using different plants Properties of a good phytoremediator: • high tolerance to the pollutants • high biomass production, fast growth • large, deep root system • good accumulator/degrader of pollutant • able to compete with other species • economic value

Uses of phytoremediation (cont.) Popular plants for phytoremediation • trees various organics metals poplar yellow poplar gum tree willow

Uses of phytoremediation (cont.) Popular plants for phytoremediation (cont.): Brassicaceae: • For inorganics • grasses

Thlaspi Alyssum Brassica juncea

Uses of phytoremediation (cont.) Popular plants for phytoremediation (cont.): various grasses for organics hemp buffalo grass red fescue for inorganics bamboo kenaf

Uses of phytoremediation (cont.) Popular plants for phytoremediation aquatic plants cattail parrot feather salicornia for organics poplar, willow reed spartina

Phytoremediation

Solar energy In situ Fossil fuels for energy Ex situ

Mechanical/chemical treatment

• Soil washing • Excavation + reburial • Chemical cleanup of soil/water • Combustion

Phytoremediation vs. Mechanical/chemical treatment

Advantages of phytoremediation

• Cheaper ~10 - 100x Excavation & reburial: up to $1 million/acre Revegetation: ~$20,000/acre

Phytoremediation vs. Mechanical/chemical treatment Advantages of phytoremediation (cont.) • Less intrusive • Can be more permanent solution • Better public acceptance

Phytoremediation vs. Mechanical/chemical treatment (cont.)

Limitations of phytoremediation

• Can be slower Limited by rate of biological processes

-

-Accumulation

in plant tissue: slow e.g. metals: average 15 yrs to clean up site Filter action by plants: fast (days) - Metabolic breakdown (organics): fairly fast (< 1yr)

Phytoremediation vs. Mechanical/chemical treatment (cont.) Limitations of phytoremediation (cont.) • Limited root depth Trees > prairie grasses > forbs, other grasses Max depth ~5 m Can be increased up to 20m with “deep planting”

Phytoremediation vs. Mechanical/chemical treatment (cont.) Limitations of phytoremediation (cont.) • Plant tolerance to pollutant/conditions - Bigger problem with metals than organics - Can be alleviated using amendments, or treating hot spots by other method • Bioavailability of contaminant - Bioavailability can be enhanced by amendments

So, when choose phytoremediation?

• Sufficient time available • Pollution shallow enough • Pollutant concentrations not phytotoxic • $$ limited Note: Phyto may be used in conjunction with other remediation methods

For very large quantities of mildly contaminated substrate:

phytoremediation only cost-effective option

Phytoremediation processes

Phytoremediation processes

phytostabilization

•

Phytostabilization

: pollutant immobilized in soil - Metals - Non-bioavailable organics 1. Plants reduce leaching, erosion, runoff  pollutant stays in place 2. Plants + microbes may transform pollutant to less bioavailable form (e.g. metal precipitation on roots)

Phytoremediation processes

phytostimulation

•

Phytostimulation

: plant roots stimulate degradation of pollutant by rhizosphere microbes Organics e.g.

PCBs, PAHs bacteria, fungi

Phytoremediation processes

phytodegradation

•

Phytodegradation

: plants degrade pollutant, with/without uptake, translocation Via enzymes, e.g. oxygenases nitroreductase Certain organics e.g.

TCE, TNT, atrazine in tissues or in root exudate

Phytoremediation processes

accumulation phytoextraction

•

Phytoextraction

: pollutant accumulated in harvestable plant tissues mainly inorganics: metals metalloids radionuclides Plant biomass may be used (e.g. to mine metals, or non-food industrial use) or disposed after minimizing volume (incineration, composting)

Phytoremediation processes

phytovolatilization

•

Phytovolatilization

: pollutant released in volatile form into the air some metal(loid)s: Se, As, Hg some volatile organics: TCE, MTBE

Phytoremediation applications may involve multiple processes at once volatilization stabilization accumulation degradation

water

Rhizofiltration

•

Rhizofiltration

: pollutant removed from water by plant roots in hydroponic system for inorganics metals metalloids radionuclides Plant roots & shoots harvestable (may be used to mine metals) or disposed after minimizing volume

• Hydroponics for metal remediation: 75% of metals removed from mine drainage Rhizofiltration

Involves:

• phytoextraction • phytostabilization

• Constructed wetland for Se remediation: 75% of Se removed from ag drainage water

Involves:

•phytoextraction • phytovolatilization • phytostabilization • (rhizofiltration) • (phytostimulation)

• •

Natural attenuation Vegetative cap

: : polluted site left alone but monitored polluted site revegetated, then left alone, monitored with/without adding clean topsoil

Hydraulic barrier

Water flow redirected Pollutants intercepted

H 2 O

Phytoremediation project (1996-) (Phytokinetics inc.) Oregon site Soil polluted with PAHs Planted with grass (Lolium perenne) Results: bare soil: some PAH removal vegetated soil: increased PAH removal (~4x) Process?

Phytostimulation/phytodegradation

Phytoremediation project (1995-1998) (Phytotech inc.) New Jersey site Soil polluted with lead (Pb) Planted with Indian mustard (Brassica juncea) Results (after 3 growing seasons): bare soil: 6% reduction in Pb vegetated soil: 29% reduction in Pb Process?

Phytoextraction

Phytoremediation project (1997) (COE) Mississippi site Groundwater polluted with TNT pumped through constructed wetland Results: 95% reduction in TNT

endogenous plant enzymes found to degrade TNT

Process?

Phytodegradation

Some light reading:

Print from Course Website •EPA: Citizen’s guide to Phytoremediation •EPA: Citizen’s guide to Natural Attenuation •Pilon-Smits, 2005 Phytoremediation (review) Ann Rev Plant Biology