Soil and Land Treatment
Types of Land Treatment
Soil Treatment or Land treatment refers to the removal of contaminant from soil either on site or away from the site of contamination.
Bio-remediation - The use of biological mechanisms to destroy, transform, or immobilize environmental contaminants in order to protect potential sensitive receptors
Phyto-remediation - treatment with the help of plants
Ex situ remediation techniques involve removing the soil from the subsurface to treat it
Composting consists of excavating the soil and then mixing organics such as wood, hay, manure, and vegetative waste with the contaminated soil. The organics are chosen based on their ability to provide the proper porosity and carbon and nitrogen balances to aid in the breakdown of contaminants. Maintaining thermophilic temperatures 54 to 65 degree C is an important part of composting. In most cases, the indigenous microorganisms maintain this temperature while degrading the contaminant. Composting is most effective when removing PAH, TNT, and RDX.
It is a process in which the soil is excavated and mechanically separated via sieving. The polluted soil is then place in layers no more than 0.4 meters thick.. Oxygen is added and mixing occurs via plowing, harrowing, or milling. Nutrients and moisture may also be added to aid the remediation process. The pH of the soil is also regulated (keeping it near 7.0) using crushed limestone or agricultural lime.
Excavated soils are mixed with soil amendments and placed in aboveground enclosures. It is an aerated static pile composting process in which compost is formed into piles and aerated with blowers or vacuum pumps. Soil is piled, nutrients, microbes, oxygen, and substrate are added to start the biological degradation of the contaminants. Nutrients such as mineral fertilizers may also be added. Additionally, microorganisms such as fungi, bacteria, or enzymes could be added.
Bioreactors are also used depending on the amount of soil need to be treated.
Prevention of Soil Pollution
Prevention is always the most preferred option before the release of any contaminant in environment.