Microbial Data to Support Landfarming and Biopiles

Landfarming and biopiles are two ex situ methods for soil and sediment remediation. Landfarming relies on agricultural practices, including tilling, fertilizing, and aerating, to stimulate contaminant biodegradation. Excavated soil or dredged sediment is spread over a prepared area and potentially mixed with the soil underneath. The addition of nutrients, oxygen, and moisture create an environment favorable for aerobic biodegradation. A bulking agent like hay may also be added to increase soil permeability and air circulation. Proper controls must be in place to prevent spreading contamination off-site through leachate, vapor, or dust.

Bioremediation via biopiles is like landfarming except the excavated soil or sediment is placed in piles or mounds on an impermeable surface. A passive or forced air aeration system may also be in place. The biodegradation processes produce heat, which raises the soil temperature and stimulates further biodegradation. Biopiles may be covered to retain heat and prevent precipitation from creating excessive leachate.

Both methods are primarily used to treat compounds that degrade aerobically, including fuel hydrocarbons like those found at underground storage tank (UST) sites, drill cuttings, and petroleum refinery wastes. The duration of the treatment depends on the mixture of contaminants as low-molecular weight compounds are more readily degraded compared to compounds like naphthalene and other PAHs that have higher molecular weights. Microbial analysis can be used to monitor hydrocarbon-degrading microorganisms over the course of treatment.