Transcript document

Emerging/New Technologies
ENVM 644: New Technologies in Environmental Management
Dr. Robert Beauchamp
PHYTOREMEDIATION

NEW & UNIQUE
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EXPLOITS NATURAL PROPENSITIES OF CERTAIN
PLANTS TO REMOVE CONTAMINANTS FROM
SOIL/WATER
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CAN REMOVE ORGANICS & METALS
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NEED A MANAGEMENT GUIDE
PHYTOREMEDIATION (cont)
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PLANTS CAN METABOLIZE CONTAMINANTS IN SHOOTS
OR
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RELEASE CHEMICALS THAT CAN REACT WITH THE
CONTAMINANT & DIMINISH THE HAZARD.
OR
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INDIRECT EFFECTS – INTERACTIONS BETWEEN ROOTS,
MICROBES & SUBSTRATES ENHANCE MICROBE ACTIVITY
WHICH CAN DEGRADE CONTAMINANTS
(RHIZOREMEDIATION)
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DIRECT & INDIRECT PROCESS CAN OCCUR
CONCURRENTLY.
MANAGER SHOULD KNOW WHETHER
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UPTAKE & METABOLISM OF CONTAMINANT WILL
RESULT IN COMPLETE REMOVAL & DETOX.
OR
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A TRANSFORMATION PRODUCT HAS ACCUMULATED
IN THE PLANT (CAN BE HAZARDOUS).
OR
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WHETHER PLANT-MICROBE INTERACTION IN ROOTS
HAS DEGRADED CONTAMINANT IN THE MATRIX.
NATURE OF CONTAMINANT WILL:
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DETERMINE PARTITIONING INTO WATER PHASE (SOLUBILITY) O
LIPID PHASE IN A MATRIX (FAT SOLUBILITY).
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LIPOPHILICITY OF A CONTAMINANT CONTROLS ITS AVAILABILIT
& TRANSLOCATION IN A PLANT.
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MEASURED AS OCTANOL-WATER PARTITION COEF. (KOW).
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KOW – RATIO: CONTAMINANT CONC. IN ORGANIC SOLVENT TO I
CONC. IN WATER.
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LOW KOW = HIGH WATER SOLUBLE COMPOUND
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HIGH KOW = HIGH FAT-SOLUBLE COMPOUND
GENERAL RULE:
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UPTAKE OF ORGANICS BY PLANT ROOTS INCREASES WITH
INCREASING KOW.
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FOR TRANSLOCATION – AN OPTIMUM KOW EXISTS.
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COMPOUNDS WITH LOW KOW < 10 ARE NOT READILY
UPTAKEN BY ROOTS. CAN FLOW AWAY.
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IF LOW KOW ENTERS PLANT, ANY TRANSLOCATION IS LIMITED
BY LIPID COMPONENTS OF PLANT TISSUES.
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HIGH FAT-SOLUBLE COMPOUNDS, KOW >103, HAVE LIMITED
DELIVERY TO ROOTS DUE TO LOW WATER SOLUBILITIES &
HIGH PARTITIONING TO LIPID PHASES IN THE MATRIX.
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COMPOUNDS MOST READILY TAKEN UP AND TRANSLOCATED
INTO PLANTS HAVE KOW BETWEEN 10 - 103.
IMPORTANT FOR MANAGER:
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AN OPTIMUM KOW EXISTS FOR TRANSLOCATION OF
ORGANICS.
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MANY CHEMICALS & PESTICIDES FALL IN THE RANGE
FOR UPTAKE & TRANSLOCATION (KOW 10-103).
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PCB’S, HYDROCARBONS, DIOXINS HAVE KOW’s 104-1010.
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MOST SUCCESSFUL WHEN FOCUS IS ON STIMULATION
OF RHIZOSPHERE BIODEGRADATION INSTEAD OF
PROMOTING PLANT UPTAKE & METABOLISM.
PLANT ENZYMES
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CAN CAUSE TRANSFORMATIONS WITHIN THE PLANT.
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ENZYMES CAN TRANSFORM CONTAMINANTS OUTSIDE
THE PLANT (EXPLANTA).
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CAN TRANSFORM MUNITION WASTE (TNT) & ORGANIC
DEGREASERS (TCE).
ENHANCED MICROBIAL ACTIVITY IN PLANT RHIZOPHERES
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CAN SPEED UP ANY TRANSFORMATIONS.
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NEED SUITABLE PHYSIOCHEMICAL ENVIRONMENTS.
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PLANTS ROOT EXUDATES, I.E. CARBOHYDATES &
AMINO ACIDS. ENHANCES GROWTH / BIOACTIVITY OF
MICROBIAL COMMUNITIES IN SOIL & PROMOTES
DEGRADATION.
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BIOFILMS ON ROOT SURFACES (PLANT MUCILAGE)
PROMOTES DEVELOPMENT OF MICROBES.
MICROBIAL RESPIRATORY ACTIVITY CAN REDUCE O2 CONC. &
CREATE REDUCED ENVIRONMENTS. CAN TRANSFORM
HIGHLY CHLORINATED COMPOUNDS.
METALS REMEDIATION POTENTIAL
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SOILS CONTAMINATED BY METALS:
– MINING
– MANUFACTURING
– URBAN ACTIVITIES
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CAN DISRUPT ECOSYSTEMS
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CAUSE HEALTH PROBLEMS
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INJURE PLANTS
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CAUSE ANIMAL FATALITIES
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LEAD PROBLEM – CHILDREN
METALS REMEDIATION POTENTIAL (cont)
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EXAMINED TECHNOLOGIES
–
–
–
–
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EXCAVATION
ELECTROCHEMICAL
ENCAPSULATING
PHYSICAL
METALS ARE NOT BIODEGRADABLE.
MICROBIAL PROCESSES OFFER PROMISE.
A MICROBIAL PROCESS INVOLVES OXIDATION-REDUCTION
REACTIONS
TRANSFORMS METAL SPECIES FROM SOLUBLE, MOBILE AND
MORE TOXIC INTO INSOLUBLE, LESS MOBILE & LESS TOXIC
FORM.
THEN SEPARATED BY CHEMICAL/PHYSICAL PROCESS.
EX. REDUCTION OF HAZARDOUS, SOLUBLE Cr6+ to
INSOLUBLE, LESS MOBILE & LESS TOXIC Cr3+, AND CHEMICAL
PRECIP. AS Cr (OH)3.
HYPERACCUMULATORS:
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CERTAIN PLANTS CAN REMOVE METALS FROM
MATRICES BY UPTAKE, TRANSLOCATION, &
ACCUMULATION IN SHOOTS.
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A HYPERACCUMULATOR CAN YIELD GREATER THAN OR
EQUAL TO 0.1 % Cr, Ni, Co OR GREATER THAN 1.0% Zn or
Mn IN ABOVE GROUND SHOOTS ON A DRY WEIGHT
BASIS.
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ECONOMIC VALUE - CAN LEAD TO
PHYTOMINING/PHYTOEXTRACTION
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SOME PLANTS CAN ACCUMULATE UP TO 1% OF
BIOMASS FOR Zn, Ni, Co, Mn, Ar.
HYPERACCUMULATORS: (cont)
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TREES OFFER ADVANTAGE OF HIGH BIOMASS
PRODUCTION.
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TREES GENERALLY SLOW GROWING & POTENTIAL FOR
LEAF DISPERSION.
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GRASSES & CROPS HAVE HIGH GROWTH RATES &
SOME HAVE HIGH METAL ACCUMULATION.
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WITH LOW BIOMASS PRODUCTION, GRASSES TAKE
LONGER TO ACCUMULATE METALS.
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CROPS ( HIGH BIOMASS) CAN CREATE A HAZARD TO
THE FOOD CHAIN.
HYPERACCUMULATORS: (cont)
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MOST STUDIED PLANTS ARE:
– FAMILY BRASSICACSAE:
– GENERA – BRASSICA & THYLASPI
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B. JUNCEA- LEAD, CADMIUM, ZINC
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T. CAERULESCENS (ALPINE PENNYCRESS) – ZINC,
CADMIUM FAVORED WITH LOWERING THE pH.
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LOW GROWTH RATE AND LOW YIELD ARE LIMITING
FACTORS.
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BIOTECHNOLOGY CAN HELP.
REMOVAL BY PLANT ROOTS
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RHIZOFILTRATION – REMOVES METALS FROM SURFACE & GROUNDWATER BY:
• ABSORPTION
• CONCENTRATION
• PRECIPTATION
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TERRESTRIAL PLANTS ARE BEST:
– LONG, FIBROUS ROOTS
– LARGE SURFACE AREA
– EX. CONSTRUCTED WETLANDS SHALLOW LAGOONS
GW/WASTE WATER PUMPING
PHYTOSTABILIZATION:
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INTERIM CONTAINMENT STRATEGY
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FOR SITES WITH LOW METAL LEVELS BELOW RISK
THRESHOLDS.
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LARGE SCALE REMOVAL ACTION NOT FEASIBLE.
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PLANTS WITH HIGH TOLERANCE FOR METALS IN SOIL &
LOW ACCUMULATION.
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VIGOROUSLY GROWING & EXERT HYDRAULIC CONTROL
OVER TRANSPORT OF METALS.
MATRIX CONTROLS:
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PLANT ESTABLISHMENT, PROLIFERATION, &
PERFORMANCE.
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PH, OXIDATION-REDUCTION.
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COMPOSITION & DISTRIBUTION OF REACTIVE
SURFACES.
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PRESENCE OF MULTIPLE & MIXED CONTAMINATION
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INTERACTION WITH CLIMATE FACTORS
CLIMATE – TEMPERATURE
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TEMPERATE REGIONS - LIMITED TO WARMER PARTS OF
YEAR.
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SHORT- TIME AVAILABLE.
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OK WHEN NO IMMEDIATE THREAT EXISTS.
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WARMING TECHNOLOGIES EXIST/QUESTIONABLE
ECONOMIES.
SOIL MATRIX:
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MADE UP OF SOIL PHASES
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PHYSIOCHEMICAL PROPERTIES OF pH & REDOX.
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CAN INFLUENCE MOBILITY .
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CAN REGULATE CONTAMINANT EXPOSURE &
SUSCEPTIBILITIES TO BIOLOGICAL TRANSFORMATION
/REMOVAL PROCESSES.
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CONTROL PROCESSES THAT ELIMINATE/REDUCE
EFFECTS OF CONTAMINANTS IN ENVIRONMENT.
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IMPACT ORGANICS & METALS DIFFERENTLY.
COLLOIDAL NATURE EFFECTS REACTIVITY OF SOIL
PHASES (INORGANIC & ORGANIC)
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SOIL COLLOIDS ARE:
– EXTREMELY SMALL SIZE
– LARGE SURFACE AREA
– NEGATIVELY CHARGED SURFACE AREA – INFLUENCE
ATTRACTIONOR REPULSION BETWEEN SOIL &
CONTAMINANT.
ORGANIC PHASE IN SOIL:
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HIGH ORGANIC CONTENT IN SOIL
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CAN RESULT IN MODERATE TO HIGH LIPOPHILOC ORGANIC
TOXICS BEING TRAPPED IN ORGANIC MATTER.
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UNAVAILABLE FOR PLANT UPTAKE.
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CAN ENHANCE DEGRADATION IN RHIZOPHERES BY
STIMULATING MICROBIAL GROWTH & BIOACTIVITY
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METALS CAN BOND WITH ORGANICS & REDUCE AVAILABILTY
FOR PLANT UPTAKE.
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METAL BONDING WITH ORGANICS CAN ASSIST IN SITE
STABILIZATION.
ORGANIC PHASE IN SOIL: (cont)
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EX. LEAD STABILIZATION
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AVAILABILITY OF METALS IN CLAYS WITH HIGH
COLLOIDAL SOLIDS WILL BE REDUCED COMPARED WITH
SAND SOILS.
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BECAUSE:
– POSITIVE CHARGED CATIONS OF CONTAMINANTS
ATTRACTED TO NEGATIVE CHARGED MINERAL SURFACES.
– CHELATING AGENTS ARE BEING RESEARCHED TO
IMPROVE METAL AVAILABILITY.
MATRIX (SOIL) pH
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EXERTS GREATER IMPACT ON METALS.
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PLANTS ABSORB METALS IN IONIC FORM.
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METAL CONCENTRATION INCREASES WITH
DECREASING pH. (INCREASES HYDROGEN IONS
ACTIVITY).
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MAY BE TOXIC TO PLANTS.
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RESEARCH IS ON ACIDIFIERS.
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EX. SULFUR.
OXIDATION-REDUCTION
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MANY ELEMENTS ARE MORE MOBILE DEPENDING ON
OXIDATION STATE.
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EX. CHROMIUM – Cr6 IS HIGHLY OXIDIZED FORM & IS
MORE TOXIC, MORE SOLUBLE & MOBILE THAN Cr3+
(REDUCED FORM).
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PHYTOREMEDIATION MAY FAVOR PRESENCE OF Cr6.
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OTHER REMOVAL SCHEME MAY BE TO REDUCE Cr6 TO
Cr3 AND PRECIPITATE AS INSOLUBLE, IMMOBILE
HYDROXIDE, Cr(OH)3.
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THE CHOICE IS THE MANAGER’S.
DEEP ROOTED PLANTS
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EARLY ASSUMPTION THAT PHYTOREMEDIATION DEPTH
WAS LIMITED TO 15-30 CM.
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RESEARCHERS ARE DEVELOPING DEEP ROOTED PLANT
SYSTEMS.
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EX.
– HYBRID POPLAR TREES.
– GROUNDWATER CONTAINING ATRAZINE AND TNT.
METALS ARE DIFFICULT DUE TO:
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LOW SOLUBILITY
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ATTRACTION TO SOIL SURFACES
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TEND TO REMAIN IN ROOT ZONES
PRESENCE OF OTHER TOXICS
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EASILY OVERLOOKED VARIABLE THAT CAN IMPEDE
REMEDIATION
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MOST CONTAMINATED SITES CONTAIN MIXTURES OF
COMPOUNDS (ORGANICS & INORGANICS).
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AN EXAUSTIVE CHARCTERIZATION MAY BE REQUIRED
FOR DECISION.
MANAGEMENT AIDS
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REQUIREMENTS:
– POTENTIAL SUCCESS OF TECHNOLOGY
– STAKEHOLDER CONCERNS
– CAREFUL PLANNING (TEAM OF EXPERT)
– SCHEDULING
– BUDGETING
– IMPLEMENTATION
– MONITORING
– CONTROLLING
MANAGEMENT AIDS (cont)
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PRODUCES EXPECTED RESULTS.
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PLANNING:
– SITE CONDITIONS
– LEGAL REQUIREMENTS
– OBJECTIVES & TARGETS
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IMPLEMENTATION:
– RESPONSIBILITIES/AWARNESS
– COMMUNICATION
– DOCUMENTATION OF PROCESS
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MONITORING:
– MEETING OBJECTIVES & TARGETS
– ANY CORRECTIVE ACTION
TEAM OF EXPERTS
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TECHNICAL EXPERTISE REQUIRED
– MICROBIAL BIOLOGY
– SOIL SCIENCE/GEOLOGY
– HYDROLOGY
– PLANT PHYSIOLOGY
– PROJECT MANAGEMENT
RECOVERY OF CONTAMINANTS
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HARVEST CONTAMINATED PLANTS
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LOW GRADE ORE (PHYTOMINING)
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RECYCLED
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UNDISTURBED ENVIRONMENT
ESTIMATED FINANCIAL RECOVERIES:
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HYPERACCUMULATOR PRODUCE 10-20 TONS
BIOMASS/HECTARE/YR WITH VOLUME 10O
KG/HECTER/YR (FOR NICKEL, WOULD RECOVER
$550/HECTARE AT MARKET VALUE OF $2.50/LB.)

$960/HECTARE WITH ALFALFA PRODUCTION OF 500 KG
OF Zn/HECTARE AT $1.92/KG.
ESTIMATED COMPARISON COSTS
TECHNOLOGY
COST/TON
PHYTOREMEDIATION
$25 – 100
ELECTROKINETICS
20 – 200
SOIL FLUSHING
40 – 190
SOIL WASHING
75 - 200
LANDFILLING
100 – 400
VITRIFICATION
400 – 850
CONCLUSIONS
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PHYTOREMEDIATION :
– PERMANENT IN-SITU OPTION
– PHYTOMINING CAN BE PROFITABLE
– MANY PLANTS HAVE ABILITY TO CONCENTRATE
CONTAMINANTS IN SHOOTS & LEAVES
– DEPENDENT ON CLIMATE, MATRIX, pH, REDOX POTENTIAL,
KOW, ORGANIC MATTER.
– PLANNING, SCHEDULE, BUDGET, CONTROLS,
MONITORING SYSTEM, PROJECT MANAGER, TEAM OF
EXPERTS, TOP SUPPORT SUPPORT.
– RECYCLING CAN DEFRAY COSTS.