ex-situ soil washing

1. Superviser :Dr. Mahdi O. karkush
:Shahad Duja AliWritten by
Soil washing

2. introduction
Soil washing is the process in which water is used
to remove contaminants from soil such an organic
,inorganic and radioactive contaminants . The
process works by either dissolving or suspending
contaminants in the wash solution. Washing
separates the small particles from the large
particles by breaking adhesive bonds. The
separated material is smaller in volume and is
more easily disposed.

3. application
Soil washing may be used to treat soil contianing :
1.petroleum
2.Radoincludes
3.Heavy metal
4.Polychlorinated biphenyls(PCBS)
5.Pentachlorophenol(PCP)
6.Pesticides
7.Cyanides
8.Creosote

4. Soil washing is most appropriate for treating
noncomplex soil that contain at least 50% sand and
gravel and is relatively ineffective in treating soils
that are rich in clay and silt. Further soils with a
relatively high cation exchange capacity tend to
bind pollutants more tightly which can limit the
ability of the soil washing processto effectively
separate the pollutant from the soil .

5. Soil washing process
 Soil washing can be broken into six different steps :
 Pretreatment
 Separation
 Coarse-grained treatment
 Fine-grained treatment
 Process water treatment
 Residuals management

6. soil washing diagram

7. Advantage
1- soil washing is very cost effective when it can reduce the
amount of soil that needs further treatment or disposal. Soil
washing, when performed under ideal conditions, can lead to
a volume reduction of approximately 90% of the originally
contaminated soil.
2- soil washing is performed on site in a closed system
where the conditions, such as pH level and
temperature, of the soil being treated can be
controlled and closely monitored .
3-generally the process can be run at a very high rate of
around 100 cubic yards per day.

8. Disadvantage
1-Soil washing requires a large area in order to set up the
system .
2- Soil washing is also predominantly effective with soils
that are very coarse. The higher the percentage of
coarse grains the more successful soil washing will be
at remediating a contaminated site.
3- oil washing is ineffective for soils containing more
than 30 to 50% silt, clay or organic matter.

9. Calculations
An equation that relates the contaminant
concentration in soil washing is:
where Csi is the initial concentration of the
contaminant in the soil (mg/kg), Ms is the total dry
mass of the soil (kg), Csf is the final concentration of
the contaminant in the soil after washing (mg/kg),
Vl is the total volume of the washing solution (L), and
Cl is the concentration of the contaminant in the
solution (mg/L).
……..(1)

10. (Kd) coefficient of the contaminant
……….(2)
Equation 2 can be substituted into Equation 1 to find
the removal efficiency, which is given by:
………..(3)

11. Or can be founded the removal efficiency by the
equation below:-
………(4)

12. References
1-ART Engineering. “Soil Washing at King of Prussia Superfund Site” <
http://www.art-engineering.com/Projects/KOP-Soil/Photos.htm>
(Mar. 16, 2013).
2-Fristad, W. E. (1995). “Case Study: Using soil washing/leaching for the removal
of heavy metal at the twin cities army ammunition plant.” Remediation, 5(4),
61-72.
3-Griffiths, Richard A. (1995). “Soil-washing technology and practice.” Journal of
Hazardous Materials. 40. 175-189.
4-Sharma, Hari D., and Krishna R. Reddy (2004). "Soil Remediation
Technologies." Geoenvironmental Engineering: Site Remediation, Waste
Containment, and Emerging Waste Management Technologies. Wiley,
Hoboken, NJ, 413-421.
5-USEPA. (1991, September). “Guide for Conducting Treatability Studies
Under CERCLA: Soil Washing.” Washington D.C., EPA/540/2-91/020A.