Phytoremediation of heavy metals-concepts and applications

Содержание

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Uses of phytoremediation air soils, sediments groundwater wastewater streams - industrial

Uses of phytoremediation

air
soils, sediments
groundwater
wastewater streams
- industrial


- agricultural
- municipal, sewage

Remediation of different media:

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Uses of phytoremediation (cont.) inorganics: - metals (Pb, Cd, Zn, Cr,

Uses of phytoremediation (cont.)

inorganics:
- metals (Pb, Cd, Zn, Cr,

Hg)
- metalloids (Se, As)
- “nutrients” (K, P, N, S)
- radionuclides (Cs, U)

Remediation of different pollutants:

organics:
- PCBs
- PAHs
- TCE
TNT
MTBE
- pesticides
- petroleum
hydrocarbons
Etc.

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Uses of phytoremediation (cont.) farming polluted soil irrigation with polluted groundwater

Uses of phytoremediation (cont.)

farming polluted soil
irrigation with polluted

groundwater
letting trees tap into groundwater
letting plants filter water streams
constructed wetlands, hydroponics

Remediation using different systems:

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Hydraulic barrier different systems:

Hydraulic barrier

different systems:

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Vegetative cap different systems:

Vegetative cap

different systems:

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Constructed wetlands different systems:

Constructed wetlands

different systems:

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different systems: hydroponics with polluted wastewater

different systems:

hydroponics with polluted wastewater

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

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

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Uses of phytoremediation (cont.) high tolerance to the pollutants high biomass

Uses of phytoremediation (cont.)

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

Properties of a good phytoremediator:

Remediation using different plants

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Uses of phytoremediation (cont.) trees Popular plants for phytoremediation various organics

Uses of phytoremediation (cont.)

trees

Popular plants for phytoremediation

various organics
metals

poplar

willow

gum tree

yellow

poplar
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Uses of phytoremediation (cont.) For inorganics Popular plants for phytoremediation grasses

Uses of phytoremediation (cont.)

For inorganics

Popular plants for phytoremediation

grasses


(cont.):

Brassica juncea

Alyssum

Thlaspi

Brassicaceae:

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Uses of phytoremediation (cont.) Popular plants for phytoremediation (cont.): hemp kenaf

Uses of phytoremediation (cont.)

Popular plants for phytoremediation

(cont.):

hemp

kenaf

bamboo

various grasses

red fescue

buffalo

grass

for organics

for inorganics

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Uses of phytoremediation (cont.) Popular plants for phytoremediation parrot feather poplar,

Uses of phytoremediation (cont.)

Popular plants for phytoremediation

parrot feather

poplar, willow


spartina

halophytes

salicornia

reed

aquatic plants

cattail

for organics

for inorganics

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Advantages & Limitations of Phytoremediation

Advantages & Limitations of Phytoremediation

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Phytoremediation Mechanical/chemical treatment Soil washing Excavation + reburial Chemical cleanup of soil/water Combustion

Phytoremediation

Mechanical/chemical treatment

Soil washing
Excavation + reburial
Chemical cleanup of soil/water

Combustion
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Phytoremediation vs. Mechanical/chemical treatment Cheaper Advantages of phytoremediation ~10 - 100x

Phytoremediation vs.
Mechanical/chemical treatment

Cheaper

Advantages of phytoremediation

~10 - 100x

Excavation & reburial:

up to $1 million/acre

Revegetation: ~$20,000/acre

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Phytoremediation vs. Mechanical/chemical treatment Advantages of phytoremediation (cont.) Less intrusive Can

Phytoremediation vs.
Mechanical/chemical treatment

Advantages of phytoremediation (cont.)

Less intrusive
Can be

more permanent solution
Better public acceptance
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Limitations of phytoremediation Phytoremediation vs. Mechanical/chemical treatment (cont.) Can be slower

Limitations of phytoremediation

Phytoremediation vs.
Mechanical/chemical treatment (cont.)

Can be slower

Limited by

rate of biological processes

- Metabolic breakdown (organics): fairly fast

- Filter action by plants: fast (days)

Accumulation in plant tissue: slow
e.g. metals: average 15 yrs to clean up site

(< 1yr)

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Limitations of phytoremediation (cont.) Phytoremediation vs. Mechanical/chemical treatment (cont.) Limited root

Limitations of phytoremediation (cont.)

Phytoremediation vs.
Mechanical/chemical treatment (cont.)

Limited root depth

Trees

> prairie grasses > forbs, other grasses
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Limitations of phytoremediation (cont.) Phytoremediation vs. Mechanical/chemical treatment (cont.) Plant tolerance

Limitations of phytoremediation (cont.)

Phytoremediation vs.
Mechanical/chemical treatment (cont.)

Plant tolerance to

pollutant/conditions

Bioavailability of contaminant

- Bigger problem with metals than organics
- Can be alleviated using amendments, or treating hot spots by other method

- Bioavailability can be enhanced by amendments

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So, when choose phytoremediation? Sufficient time available Pollution shallow enough Pollutant

So, when choose phytoremediation?

Sufficient time available
Pollution shallow enough

Pollutant concentrations not phytotoxic

For very large quantities of mildly
contaminated substrate:
phytoremediation only cost-effective option

Note: Phyto may be used in conjunction with
other remediation methods

$$ limited

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Techniques/strategies of phytoremediation phytoextraction (or phytoaccumulation), phytostabilization, Phytostimulation, phytofiltration, phytovolatilization, and phytodegradation

Techniques/strategies of phytoremediation

phytoextraction (or phytoaccumulation),
phytostabilization,
Phytostimulation,
phytofiltration,
phytovolatilization,
and phytodegradation

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Phytoextraction Phytoextraction (also known as phytoaccumulation, phytoabsorption or phytosequestration) is the

Phytoextraction

Phytoextraction (also known as phytoaccumulation, phytoabsorption or phytosequestration) is the uptake

of contaminants from soil or water by plant roots and their translocation to and accumulation in aboveground biomass i.e., shoots.
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accumulation phytoextraction Phytoremediation processes

accumulation

phytoextraction

Phytoremediation processes

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Phytoextraction: pollutant accumulated in harvestable plant tissues

Phytoextraction: pollutant accumulated
in harvestable plant tissues

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Phytostabilization Phytostabilization or phytoimmobilization is the use of certain plants for

Phytostabilization

Phytostabilization or phytoimmobilization is the use of certain plants for

stabilization of contaminants in contaminated soils
is used to reduce the mobility and bioavailability of pollutants in the environment, thus preventing their migration to groundwater or their entry into the food chain.
Plants can immobilize heavy metals in soils through:
sorption by roots,
precipitation,
complexation or metal valence reduction in rhizosphere etc.
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Phytoremediation processes

Phytoremediation processes

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Phytoremediation processes phytostabilization

Phytoremediation processes

phytostabilization

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Phytostabilization: pollutant immobilized in soil

Phytostabilization:
pollutant immobilized in soil

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phytostimulation Phytoremediation processes

phytostimulation

Phytoremediation processes

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Phytostimulation: plant roots stimulate degradation of pollutant by rhizosphere microbes

Phytostimulation: plant roots stimulate
degradation of pollutant
by

rhizosphere microbes
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Phytodegradation Phytodegradation is the degradation of organic pollutants by plants with

Phytodegradation

Phytodegradation is the degradation of organic pollutants by plants with

the help of enzymes such as dehalogenase and oxygenase; it is not dependent on rhizospheric microorganisms .
Plants can accumulate organic xenobiotics from polluted environments and detoxify them through their metabolic activities (‘‘Green Liver’’ for the biosphere).
Limitations:
Heavy metals are non-biodegradable.
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phytodegradation Phytoremediation processes

phytodegradation

Phytoremediation processes

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Phytodegradation: plants degrade pollutant, with/without uptake, translocation Certain organics e.g. TCE, TNT, atrazine

Phytodegradation:
plants degrade pollutant,
with/without uptake, translocation

Certain organics
e.g. TCE, TNT,

atrazine
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Phytovolatilization Phytovolatilization is the uptake of pollutants from soil by plants,

Phytovolatilization

Phytovolatilization is the uptake of pollutants from soil by plants,

their conversion to volatile form and subsequent release into the atmosphere. This technique can be used for organic pollutants and some heavy metals like Hg and Se.

Disadvantage:
use is limited by the fact that it does not remove the pollutant completely; only it is transferred from one segment (soil) to another (atmosphere) from where it can be redeposited.

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Phytoremediation processes phytovolatilization

Phytoremediation processes

phytovolatilization

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Phytovolatilization: pollutant released in volatile form into the air

Phytovolatilization: pollutant released
in volatile form into the air

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Rhizodegradation Rhizodegradation refers to the breakdown of organic pollutants in the

Rhizodegradation

Rhizodegradation refers to the breakdown of organic pollutants in the soil

by microorganisms in the rhizosphere. Rhizosphere extends about 1 mm around the root and is under the influence of the plant.
Plants can stimulate microbial activity about 10–100 times higher in the rhizosphere by the secretion of exudates containing carbohydrates, amino acids, flavonoids.
The release of nutrients-containing exudates by plant roots provides carbon and nitrogen sources to the soil microbes and creates a nutrient-rich environment in which microbial activity is stimulated.
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Rhizofiltration water

Rhizofiltration

water

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Rhizofiltration: pollutant removed from water by plant roots in hydroponic system metals metalloids radionuclides

Rhizofiltration: pollutant removed from
water by plant roots in hydroponic

system

metals
metalloids
radionuclides

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Phytofiltration Phytofiltration is the removal of pollutants from contaminated surface waters

Phytofiltration

Phytofiltration is the removal of pollutants from contaminated surface waters

or waste waters by plants.
Phytofiltration may be:
rhizofiltration (use of plant roots);
blastofiltration (use of seedlings) or caulofiltration (use of excised plant shoots; Latin caulis = shoot)
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Rhizofiltration Hydroponics for metal remediation: 75% of metals removed from mine drainage Involves: phytoextraction phytostabilization

Rhizofiltration

Hydroponics for metal remediation:

75% of metals removed from mine drainage

Involves:


phytoextraction
phytostabilization
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Constructed wetland for Se remediation: Involves: phytoextraction phytovolatilization phytostabilization (rhizofiltration) (phytostimulation)

Constructed wetland for Se remediation:

Involves:
phytoextraction
phytovolatilization
phytostabilization
(rhizofiltration)
(phytostimulation)


75% of Se removed from ag drainage water

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Phytodesalination Phytodesalination refers to the use of halophytic plants for removal

Phytodesalination

Phytodesalination refers to the use of halophytic plants for removal

of salts from salt-affected soils in order to enable them for supporting normal plant growth.
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stabilization degradation volatilization accumulation Phytoremediation applications may involve multiple processes at once

stabilization

degradation

volatilization

accumulation

Phytoremediation applications may involve
multiple processes at once

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Summary of phytoremediation techniques

Summary of phytoremediation techniques

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Natural attenuation: polluted site left alone but monitored Vegetative cap: polluted

Natural attenuation: polluted site left alone
but monitored

Vegetative cap:

polluted site revegetated,
then left alone, monitored
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Hydraulic barrier Water flow redirected Pollutants intercepted

Hydraulic barrier

Water flow redirected
Pollutants intercepted

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Heavy metals problems in the context of PHYTOREMEDIATION

Heavy metals problems in the context of PHYTOREMEDIATION

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heavy metals originate from extraction of ores and processing heavy metals

heavy metals originate from extraction of ores and processing
heavy metals

are non-biodegradable,
they accumulate in the environment
subsequently contaminate the food chain.
heavy metals cause toxicological effects on soil microbes, which may lead to a decrease in their numbers and activities
This contamination poses a risk to environmental and human health.
Essential HM: Fe, Mn, Cu, Zn, and Ni
Non-essential HM: Cd, Pb, As, Hg, and Cr.

Heavy metals & organic compounds

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Anthropogenic sources Sources of heavy metals in the environment Natural sources

Anthropogenic sources

Sources of heavy metals in the environment

Natural sources

weathering of

minerals,
erosion and volcanic activity

mining,
smelting,
electroplating,
use of pesticides and (phosphate)
fertilizers as well as biosolids in agriculture,
sludge dumping,
industrial discharge,
atmospheric deposition, etc.

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Sources of HM

Sources of HM

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Harmful effects of heavy metals on human health are toxic and

Harmful effects of heavy metals on human health

are toxic and

can cause undesirable effects and severe problems even at very low concentrations
cause oxidative stress
can replace essential metals in pigments or enzymes disrupting their function
the most problematic heavy metals are Hg, Cd, Pb, As, Cu, Zn, Sn, and Cr
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Harmful effects of HM

Harmful effects of HM

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Cleanup of heavy metal-contaminated soils Cleanup of heavy metal-contaminated soils is

Cleanup of heavy metal-contaminated soils

Cleanup of heavy metal-contaminated soils is utmost

necessary in order to minimize their impact on the ecosystems.
The conventional remediation methods include in situ vitrification, soil incineration, excavation and landfill, soil washing, soil flushing, solidification, and stabilization of electro-kinetic systems
Disadvantages: high costs, intensive labor, irreversible changes in soil properties and disturbance of native soil microflora, secondary pollution etc.
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Phytoremediation – a green solution to the HM problem ‘‘Phytoremediation basically

Phytoremediation – a green solution to the HM problem

‘‘Phytoremediation basically

refers to the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environments’’ (Greipsson, 2011).
It can be used for removal of heavy metals and radionuclides as well as for organic pollutants (such as, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, and pesticides).
It is a novel, cost-effective, efficient, environment- and eco-friendly, in situ applicable, and solar-driven remediation strategy.
Plants generally handle the contaminants without affecting topsoil, uptake pollutants from the environment .
low installation and maintenance costs.
The establishment of vegetation on polluted soils also helps prevent erosion and metal leaching
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Purpose of phytoremediation risk containment (phytostabilization); phytoextraction of metals with market

Purpose of phytoremediation

risk containment (phytostabilization);
phytoextraction of metals with market value

such as Ni, Tl and Au;
durable land management where phytoextraction gradually improves soil quality for subsequent cultivation of crops with higher market value.
Furthermore, fast-growing and high-biomass producing plants such as willow, poplar and Jatropha could be used for both phytoremediation and energy production.
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Phytoextraction of heavy metals The main and most useful phytoremediation technique

Phytoextraction of heavy metals

The main and most useful phytoremediation technique

for removal of HM and metalloids from polluted soils, sediments or water. The efficiency depends on many factors like bioavailability of the heavy metals in soil, soil properties, speciation of the heavy metals and plant species concerned. Plants suitable for phytoextraction should ideally have the following characteristics:
High growth rate.
Production of more above-ground biomass.
Widely distributed and highly branched root system.
More accumulation of the target heavy metals from soil.
Translocation of the accumulated heavy metals from roots to shoots.
Tolerance to the toxic effects of the target heavy metals.
Good adaptation to prevailing environmental and climatic conditions.
Resistance to pathogens and pests.
Easy cultivation and harvest.
Repulsion to herbivores to avoid food chain contamination.
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Phytoextraction: two key factors The phytoextraction potential of a plant species

Phytoextraction: two key factors

The phytoextraction potential of a plant species

is mainly determined by two key factors i.e., shoot metal concentration and shoot biomass. Two different approaches have been tested for phytoextraction of heavy metals:
(1) The use of hyperaccumulators, which produce comparatively less aboveground biomass but accumulate target heavy metals to a greater extent;
(2) The application of other plants, such as Brassica juncea (Indian mustard), which accumulate target heavy metals to a lesser extent but produce more aboveground biomass so that overall accumulation is comparable to that of hyperaccumulators due to production of more biomass.
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Bioavailability of HM in soils Chemical composition and sorption properties of

Bioavailability of HM in soils

Chemical composition and sorption properties of soil

influence the mobility and bioavailability of metals. Low bioavailability is a major limiting factor for phytoextraction of contaminants. Strong binding of heavy metals to soil particles or precipitation causes a significant fraction of soil heavy metals insoluble and therefore mainly unavailable for uptake by plants.
Bioavailability of heavy metals/metalloids in soil:
readily bioavailable (Cd, Ni, Zn, As, Se, Cu);
moderately bioavailable (Co, Mn, Fe)
and least bioavailable (Pb, Cr, U)
However, plants have developed certain mechanisms for solubilizing heavy metals in soil. Plant roots secrete metal-mobilizing substances in the rhizosphere called phytosiderophores . Secretion of H+ ions by roots can acidify the rhizosphere and increase metal dissolution. H+ ions can displace heavy metal cations adsorbed to soil particles
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Phytoextraction: two modes Natural conditions: no soil amendm. Induced or chelate

Phytoextraction: two modes

Natural conditions: no soil amendm.
Induced or chelate assisted phytoextraction:

different chelating agents such as EDTA (etylendiamintetraacetic acid), citric acid, elemental sulfur, and (NH4)2SO4 are added to soil to increase the bioavailability of heavy metals in soil for uptake by plants.
Bioavailability of the heavy metals can also be increased by lowering soil pH since metal salts are soluble in acidic media rather than in basic media. However, these chemical treatments can cause secondary pollution problems.
Use of citric acid as a chelating agent could be promising because it has a natural origin and is easily biodegraded in soil.
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Metallophytes Metallophytes are plants that are specifically adapted to and thrive

Metallophytes

Metallophytes are plants that are specifically adapted to and thrive in

heavy metal-rich soils.
Metallophytes are divided into three categories:
1. Metal excluders accumulate heavy metals from substrate into their roots but restrict their transport and entry into their aerial parts. Such plants have a low potential for metal extraction but may be efficient for phytostabilization purposes.,
2. Metal indicators accumulate heavy metals in their aerial parts and reflect heavy metal concentrations in the substrate
3. Metal hyperaccumulators are plants, which can concentrate heavy metals in their aboveground tissues to levels far exceeding those present in the soils or non-accumulating plants. These plants are concentrated in the plant family Brassicaceae. Their use especially in mining regions, either alone or in combination with microorganisms, for phytoremediation of heavy metal-contaminated soils is an attractive idea.
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Hyperaccumulation in plants The following concentration criteria for different metals and

Hyperaccumulation in plants

The following concentration criteria for different metals and metalloids

in dried foliage with plants growing in their natural habitats are proposed:
100 mg/kg for Cd, Se and Tl;
300 mg/kg for Co, Cu and Cr;
1000 mg/kg for Ni, Pb and As;
3000 mg/kg for Zn;
10000 mg/kg for Mn.
Generally, hyperaccumulators achieve 100-fold higher shoot metal concentration (without yield reduction) compared to crop plants or common nonaccumulator plants.
Hyperaccumulators achieve a shoot-to-root metal concentration ratio (called translocation factor, TF) of greater than 1.
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Hyperaccumulators The most commonly postulated hypothesis regarding the reason or advantage

Hyperaccumulators

The most commonly postulated hypothesis regarding the reason or advantage of

metal hyperaccumulation in plants is elemental defense against herbivores (by making leaves unpalatable or toxic) and pathogens.
Hyperaccumulators can be used for phytoremediation of toxic and hazardous heavy metals as well as for phytomining of precious heavy metals (such as Au, Pd and Pt). Some plants have natural ability of hyperaccumulation for specific heavy metals.
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Quantification of phytoextraction efficiency Bioconcentration factor indicates the efficiency of a

Quantification of phytoextraction efficiency

Bioconcentration factor indicates the efficiency of a plant

species in accumulating a metal into its tissues from the surrounding environment. It is calculated as follows
where Charvested tissue is the concentration of the target metal in the plant harvested tissue and Csoil is the concentration of the same metal in the soil (substrate).
Translocation factor indicates the efficiency of the plant in translocating the accumulated metal from its roots to shoots. It is calculated as follows
where Cshoot is concentration of the metal in plant shoots and Croot is concentration of the metal in plant roots.
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Quantification of phytoextraction efficiency Accumulation factor (A) can also be represented

Quantification of phytoextraction efficiency

Accumulation factor (A) can also be represented in

percent according to the following equation
where A is accumulation factor %, Cplant tissue is metal concentration in plant tissue and Csoil is metal concentration in soil. Similarly, translocation factor can also be represented in percent according to the following equation.
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Fate of plants used for phytoextraction

Fate of plants used for phytoextraction

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Phytomining Advantages: - can be combusted to get energy and the

Phytomining

Advantages:
- can be combusted to get energy and the remaining ash

is considered as ‘‘bio-ore’’;
phytomining is the sale of energy from combustion of the biomass;
bio-ore can be processed for the recovery or extraction of the heavy metals;
Processing bio-ores contributes less SOx emissions to the atmosphere;
Phytomining has been commercially used for Ni and it is believed that it is less expensive than the conventional extraction methods.
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Use of constructed wetlands for phytoremediation Constructed wetlands are used for

Use of constructed wetlands for phytoremediation

Constructed wetlands are used for clean-up

of effluents and drainage waters. Aquatic macrophytes are more suitable for wastewater treatment than terrestrial plants due to their faster growth, production of more biomass and relative higher ability of pollutant uptake.
Poplar (Populus spp.) and willow (Salix spp.) can be used on the edge. Water hyacinth (Eichhornia crassipes) has been used for phytoremediation of heavy metals at constructed wetlands. Water lettuce (Pistia stratiotes) has been pointed out as a potential phytoremediator plant for Mn contaminated waters. Azolla (short doubling time 2–3 d) has nitrogen fixation ability and tolerance to and accumulation of a wide range of heavy metals.
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Mechanism of heavy metals’ uptake, translocation, and tolerance Plants take heavy

Mechanism of heavy metals’ uptake, translocation, and tolerance

Plants take heavy metals

from soil solution into their roots. After entry into roots, heavy metal ions can either be stored in the roots or translocated to the shoots primarily through xylem vessels where they are mostly deposited in vacuoles.
The mechanism of phytoextraction of heavy metals has five basic aspects:
mobilization of the heavy metals in soil,
uptake of the metal ions by plant roots,
translocation of the accumulated metals from roots to aerial tissues,
sequestration of the metal ions in plant tissues
and metal tolerance.
Mechanisms governing heavy metal tolerance in plant cells are cell wall binding, active transport of ions into the vacuole and chelation through the induction of metal-binding peptides and the formation of metal complexes. Organic acids and amino acids are suggested as ligands for chelation of heavy metal ions because of the presence of donor atoms (S, N, and O) in their molecules.
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Role of phytochelatins and metallothioneins in phytoextraction The most important peptides/proteins

Role of phytochelatins and metallothioneins in phytoextraction

The most important peptides/proteins

involved in metal accumulation and tolerance are phytochelatins (PCs) and metallothioneins (MTs). Plant PCs and MTs are rich in cysteine sulfhydryl groups, which bind and sequester heavy metal ions in very stable complexes. PCs are small glutathione-derived, enzymatically synthesized peptides, which bind metals and are principal part of the metal detoxification system in plants. They have the general structure of (c-glutamyl-cysteinyl) n -glycine where n = 2–11.

MTs are gene-encoded, low molecular weight, metal-binding proteins, which can protect plants against the effects of toxic metal ions.

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Limitations of phytoremediation Long time required Hyperaccumulators are usually limited by

Limitations of phytoremediation

Long time required
Hyperaccumulators are usually limited by their

slow growth rate and low biomass
limited bioavailability of tightly bound fraction of metal ions from soil
It is applicable to sites with low to moderate levels of metal contamination
Risk of food chain contamination
Слайд 74

Future trends in phytoremediation Phytoremediation is a relatively recent field of

Future trends in phytoremediation

Phytoremediation is a relatively recent field of research.

Results in actual field can be different from those at laboratory or greenhouse conditions (different factors simultaneously play their role).
Factors that may affect phytoremediation in the field include:
variations in temperature,
nutrients,
precipitation and moisture,
plant pathogens and herbivory,
uneven distribution of contaminants,
soil type,
soil pH,
soil structure etc.
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Future challenges in phytoremediation Phytoremediation efficiency of different plants for specific

Future challenges in phytoremediation

Phytoremediation efficiency of different plants for specific target

heavy metals has to be tested in field conditions in order to realize the feasibility of this technology for commercialization.
Identification of desirable traits in natural hyperaccumulators --- selection and breeding techniques. Thus different desirable traits can be combined into a single plant species.
In spite of the many challenges, phytoremediation is perceived as a green remediation technology with an expected great potential.
Слайд 76

Interdisciplinary nature of phytoremediation research

Interdisciplinary nature of phytoremediation research

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Conclusions Physical and chemical methods for clean-up and restoration of heavy

Conclusions

Physical and chemical methods for clean-up and restoration of heavy metal-contaminated

soils have serious limitations like high cost, irreversible changes in soil properties, destruction of native soil microflora and creation of secondary pollution problems.
In contrast, phytoremediation is environment-friendly and ecologically responsible solar-driven technology with good public acceptance.
phytomining – a plant-based eco-friendly mining of metals, which can be used for extraction of metals even from low-grade ores.
Phytoextraction of heavy metals is expected to be a commercially viable technology for phytoremediation and phytomining of heavy metals in future.
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