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Modeling Phytoremediation of Heavy Metal Contaminated Mine Spoil Dumps. EIA and Sustainability Assessment – Asian EIA and Effective Tool Development Seol, Korea, June 5, 2007. Parikshit Verma. National Environmental Engineering Research Institute (NEERI), Nagpur.
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Modeling Phytoremediation of Heavy Metal Contaminated Mine Spoil Dumps EIA and Sustainability Assessment – Asian EIA and Effective Tool Development Seol, Korea, June 5, 2007 Parikshit Verma National Environmental Engineering Research Institute (NEERI), Nagpur
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). Definitions / Terminology 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
Metal Uptake by Plant Root Michaelis and Menton Type of Reaction
Saturated and Unsaturated Zone • Soil • Water • Soil • Air • Thin film of Water around soil particle
Saturated and Unsaturated Zone • Residual Moisture • Saturation Moisture
Moisture flux in Unsaturated Zone Relationship between Soil Moisture and Suction Head is called Soil Moisture Retention Characteristics (MRC)
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
Pedotransfer Functions Expensive and time consuming • Bulk density • Clay content • Carbon content • Particle size distribution MRC Parameters θs, θr, n, m, α f
Space – Time Domain of One Dimensional Transient Metal Uptake Model
Computational Scheme Richard’s Equation descritized using Implicit scheme
Applicability Techniques of Phytoremediation • – 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 • Phyto-transformation • Rhizosphere Bioremediation • Phyto-stabilization • Phyto-extraction • Rhizo-filtration Limitations • Limited regulatory acceptance • Long duration of time for cleanup • Potential contamination of fodder crop and food chain
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.