Contaminated Soil Remediation

Introduction

Our soil, our water and the air we breathe are our most precious natural resources. Without them we cannot exist. Population growth and concomitant agriculture, transport and industrial activities have put a tremendous strain on our natural resources and this has led to contamination and depletion of our souls on a massive scale… Only when you have personally excavated your own potatoes or grown your own tomatoes, do you really start to appreciate the beauty of our soil…

Contaminants In Soil

Common soil contaminants in soil can be physical (all kinds of debris), of biological nature (bacteria, viruses), heavy metals (Such as Arsenic), organic industrial pollutants (such as petroleum products, herbicides, insecticides), acids, bases, volatile organic compounds, radio-nuclides or solvents (such as TCE which used to be used in Dry Laundry).

Technologies Used In Contaminated Soil Remediation

Contaminated Soil treatment technologies include:

1. Chemical neutralization – using chemicals such as CaOH2 or Sodium Bi Sulphate to adjust the pH of the soil if it is too low or there has been an acid spill.

2. Using oxidizing agents to oxidize POP’s (persistant organic pollutants). Common Oxidants are KMnO4 and H2O2.

3. Aeration. Air can be pumped into the soil to encourage volatilization or to help bioremediating organisms breathe.

4. Bioremediation – using bacterial cultures to break down the pollutants

5. Phytoremediation: using plants to bioaccumulate certain pollutants such as Arsenic

6. Heating of soil

7. Pump and treat systems

8. Disinfection

9. Soil washing: Usually involves large machines that are caple of washing soil and conveying large amounts of earth.

Some of the most difficult contaminants to remove from soil are PFAS. These are forever chemicals that bacteria cannot break down.

Cutting Edge Technologies

Technologies like foam fractionation/ozonation and catalysed breakdown of PFAS are emerging as promising solutions for the so called Forever Chemicals.

Soil Quality Control

Soil testing Laboratory tests often check for plant nutrients in three categories:

Major nutrients: nitrogen (N), phosphorus (P), and potassium (K)
Secondary nutrients: sulfur, calcium, magnesium
Minor nutrients: iron, manganese, copper, zinc, boron, molybdenum, chlorine

The soil is also tested for heavy metals. pH of the soil and the Salinity are also important indicators of the fertility of the soil. Soil texture testing indicates the amount of sand, silt and clay in the soil.

Below is a schematic with some of the techniques used in soil remediation:

In Conclusion

Our Soil is our food. Our soil is also essential for trees and plants and the air we breathe. Let us put our minds together to protect it.

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Compiled by Rami E. Kremesti M.Sc., CSci, CEnv, CWEM

Biography of the Author:

Rami Elias Kremesti is a chartered water and wastewater treatment specialist with a background in chemistry. He has worked on a myriad of water treatment and power station projects internationally. He is a British Citizen based out of High Wycombe, UK. He has published three books on philosophical topics which he loves to ponder in his spare time.

Rami Elias Kremesti Portrait