Landfarming

Land Farming is a bioremediation treatment process that is performed in the upper soil zone or in biotreatment cells. Contaminated soils, sediments, or sludges are incorporated into the soil surface and periodically turned over (tilled) to aerate the mixture.

Applicability

This technique has been successfully used for years in the management and disposal of oily sludge and other petroleum refinery wastes. In situ systems have been used to treat near surface soil contamination for hydrocarbons and pesticides. The equipment employed in land farming is typical of that used in agricultural operations. These land farming activities cultivate and enhance microbial degradation of hazardous compounds. As a rule of thumb, the higher the molecular weight (i.e., the more rings within a polycyclic aromatic hydrocarbon), the slower the degradation rate. Also, the more chlorinated or nitrated the compound, the more difficult it is to degrade.

Reference: Theodore, L. and Reynolds, J., Introduction to Hazardous waste incineration, Wiley, New York(1987)

Limitations

Factors that may limit the applicability and effectiveness of the process include:

1. large space requirements
2. the conditions advantageous for biological degradation of contaminants are largely uncontrolled, which increases the length of time to complete remediation, particularly for recalcitrant compounds
3. inorganic contaminants are not biodegraded
4. the potential of large amounts of particulate matter released by operations
5. the presence of metal ions may be toxic to microbes and may leach from the contaminated soil into the ground.

Hydrocarbon compounds that have been identified as being not readily degraded by land farming include creosote, pentachlorophenol (PCP), and bunker C oil.