2. Chemical Treatment Of
Contaminated Soil
M.ADEEL
10-arid-969
Dept. Soil Science & Soil Water
Conservation
PMAS Arid Agriculture
University Rawalpindi
3. What is Soil Contamination????
Soil contamination is either solid or liquid
hazardous substances mixed with the
naturally occurring soil
Contaminants in the soil are physically or
chemically attached to soil particles
if they are not attached, are trapped
4. How did it get there?
Soil contamination results when hazardous substances
are either spilled or buried directly in the soil or migrate
to the soil from a spill that has occurred elsewhere.
Results Due To :
1.From a smokestack and are deposited on the
surrounding soil as they fall out of the air
2.Water that washes contamination from an area
containing hazardous substances
6. How does it hurt animals, plants and humans?
Affected Plants
Contaminants in the soil can hurt
plants when they attempt to grow in
contaminated soil and take up the
contamination through their roots
7. How does it hurt animals, plants and humans?
Contaminants soil adversely impact the health of animals and
humans when they ingest, inhale, or touch contaminated soil, or
when they eat plants or animals that have themselves been affected
by soil
8. How does it hurt animals, plants and humans?
Humans ingest and come into contact with contaminants when
they play in contaminated soil or dig in the soil as part of their
work.
Certain contaminants, when they contact our skin, are absorbed
into our bodies. When contaminants are attached to small surface
soil particles they can become airborne as dust and can be inhaled.
9. How can we clean it up?
There are three general approaches to cleaning up contaminated
soil:
1.soil can be excavated from the ground and be either treated or
disposed
2. soil can be left in the ground and treated in place
3. soil can be left in the ground and contained to prevent the
contamination from becoming more widespread and reaching
plants, animals, or humans.
10. Contaminated Soils Treatment via Ex-Situ and
In-Situ Mixing Methods
Treatment of contaminated soils by chemical oxidation processes
can offer significant cost savings.
when compared to other treatment alternatives such as
incineration or excavation and disposal
11. Contaminated Soils Treatment via Ex-Situ and
In-Situ Mixing Methods
The proportion of contaminant that is degraded by chemical,
biological or physical processes will
depend on:
• Soil type
• Contaminant distribution
• Contaminant type
• Oxidant Efficiency
• Soil/Water ratio
• Type & frequency of Mixing
• Temperature
• Treatment Duration.
12. Considerations for Treatment Design
•When designing an approach for implementing chemical
oxidation of soils one should attempt to maximize the surface area
in contact with the chemical oxidant.
•Prior to any soil shredding, a screening step should occur to
remove rocks and debris. Lime and/or bulking agents, such as
wood chips
or
•sand may be needed to improve both material handling as well as
to maximize biological degradation after the chemical oxidation.
•In soils with high clay content, soil shredding and/or blending
with a bulking agent may be needed to improve the soil structure
and porosity.
13. Sites Appropriate for Chemical Oxidation of
Contaminated Soils
Typical applicable sites are:
• Abandoned tank farms, bulk plants, where diesel fuels, gasoline
and other petroleum distillates have been handled
•Old dry cleaner sites
• Industrial facilities
14. In Situ Mixing
Use of typical construction equipment (e.g. track hoe)
often does not adequately break up soil matrices and
homogenize the mixture.
15. Ex Situ Mixing
Excavation methods can use conventional equipment to
transfer contaminated soils surface piles or windrows
where chemical oxidants are applied followed by surface
mixing by compost-turning type equipment.
16. 1. Ensures direct and immediate contact with
chemical oxidant;
2. Undergoes rapid oxidation reactions;
3. Eliminates uncertainties of subsurface geology
and hydrogeology;
4. Minimizes liability as compared to off-site
disposal.
17. 1. Not all contaminants are degraded quickly and/or
completely;
2. Predicting final treatment concentrations from
bench-scale studies are often difficult;
3. In situ treatment via soil mixing may be limited
by subsurface structures; and
4. Ex situ treatment may require significant on-site
area.
