Parikshit Verma

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Modeling Phytoremediation of Heavy Metal
Contaminated Mine Spoil Dumps

• Parikshit Verma

EIA and Sustainability Assessment Asian EIA and
Effective Tool Development Seol, Korea, June 5,
2007
National Environmental Engineering Research
Institute (NEERI), Nagpur
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Barren Manganese Mine Spoil Dump
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After 10 years - Revegetated Manganese Mine Spoil
Dump
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Definitions / Terminology
Phytoremediation Use of plants / vegetation for
in situ treatment of wastewater, contaminated
soils or sediments. Some plants shows the
capability to withstand relatively high
concentration of chemicals without toxic effects
(Hyperaccumulators).

• It is applied at sites with contamination of
• Organic Chemicals BTEX, TNT, RDX, PCBs
• Nutrient Ammonia, Phosphate, Nitrate
• Metal pollutants Lead, Cadmium, Zinc,
  Arsenic, Chromium

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Chemical uptake and translocation in the plant
body
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Unsaturated / Vadose zone
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Processes that takes place in the root zone
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Soil Water Partitioning
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Metal Uptake by Plant Root
Michaelis and Menton Type of Reaction
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Plant Root Growth
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Saturated and Unsaturated Zone

• Soil
• Water

• Soil
• Air
• Thin film of Water around soil particle

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Saturated and Unsaturated Zone

• Residual Moisture

• Saturation Moisture

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Moisture Retention Characteristics Curve
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Moisture flux in Unsaturated Zone
Relationship between Soil Moisture and Suction
Head is called Soil Moisture Retention
Characteristics (MRC)
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Mathematical models used in the Metal Uptake model

• Richards Equation
• Water uptake by plant root
• Metal uptake by plant root
• Root growth with time
• Plant root properties
• Moisture Retention Characteristics (MRC)
• Soil properties Bulk Density, Clay content,
  Carbon content etc.
• Pedotransfer Function
• Soil Water Partition of pollutants
• Hydrodynamic Dispersion
• Moisture flux joining groundwater
• Chemical species flux joining groundwater

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Pedotransfer Functions
Expensive and time consuming

• Bulk density
• Clay content
• Carbon content
• Particle size distribution

MRC Parameters ?s, ?r, n, m, a
f
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Space Time Domain of One Dimensional Transient
Metal Uptake Model
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Computational Scheme

• Richards Equation descritized using Implicit
  scheme

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Techniques of Phytoremediation
Applicability

• Other treatments are not cost effective
• Very large sites
• Low concentration of contaminants
• Only polishing treatment is required
• Where vegetation is used as final cap / site
  closure

Limitations

• Limited regulatory acceptance
• Long duration of time for cleanup
• Potential contamination of fodder crop and
  food chain

• Phyto-transformation
• Rhizosphere Bioremediation
• Phyto-stabilization
• Phyto-extraction
• Rhizo-filtration

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Why Phytoremediation Model Software ?

• Design of experiments to determine the parameters
  of sub-surface phenomenon.
• Preparation of irrigation schedule for plantation
  on mine spoil dump.
• Decision on harvesting time of plants.
• Estimation of amount of heavy metal present in
  the plant.

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NEERI PHYTOREM Model Software Demonstration