Soil Remediation Introduction
Soil remediation, also known as soil washing, is a term that refers to various processes designed to remove contaminants such as hydrocarbons (petroleum and fuel residues), heavy metals, pesticides, cyanides, volatiles, creosote, and semi-volatiles from soil. Soil remediation is needed to clean and maintain high quality standards of soil, water and air that can consequently benefit commercial cultivation, and wild flora and fauna.
Soil Remediation Techniques
There are four main types of soil remediation techniques for the removal of various pollutants and contamination from soils that have compiled enough documentation to give them prominence in use. These techniques include:
- Bioremediation: Bioremediation involves treatment of polluted soils by biological means. The process uses bacterium (aerobic and anaerobic species), particularly targeted to consume and break down hydrocarbons and other pollutants in soil. The advantage of the process also lies in the fact that when contaminate is consumed all the microbes die off. However, note that the process is more successful in soil that maintains 70 degrees F of temperature with sporadic rain for optimal moisture. And for bioremediation to be more effective in colder climates, soils should be properly covered and insulated. This is because the colder the ambient climate will be, the longer the clean-up time the process will take.
- Thermal Soil Remediation: This technique includes heating contaminated material into the PTU to evaporate hydrocarbon impurities and water. Here, polluted materials are usually treated at temperatures of 650° F to 900° F, and then discharged from the PTU into a cooling unit, which is either a mixer, or auger where water is added for cooling and dust control. The treated material is then discharged from the cooling unit via a conveying system, ready for testing, and subsequent recycling.
- Air Sparging: In air sparging, large volumes of air are injected into a polluted soil stratum to force the organic vapors outwards where they are typically treated by carbon filtering. The actual time the process takes in treatment depends upon various factors such as depth of the hydrocarbon pollution, the concentration level of contaminate, pH factor of the soil, and permeability of the soil.
- Encapsulation: The process of encapsulation does not filter contaminants from soil so much as it separates them. This can be done in many ways, but one of the most common ways includes mixing the polluted soil with lime, cement, and concrete, leading to preventing the contaminants from spreading to clean soil. However, this method impedes using the soil for cultivation.