Land Farming
Description
Land Farming is a bioremediation
technology. Contaminated soils are mixed with soil amendments such as
soil
bulking agents and nutrients, and then they are tilled into the earth.
The
material is periodically tilled for aeration.
Contaminants
are degraded, transformed, and immobilized by microbiological processes
and by
oxidation. Soil conditions are controlled to optimize the rate of
contaminant
degradation. Moisture content, frequency of aeration, and pH are all
conditions
that may be controlled. Land Farming differs from composting
because it actually incorporates contaminated soil into soil that is
uncontaminated. Composting also generally takes place in aboveground
piles.
Limitations and Concerns
A land farm must be managed properly to prevent both on-site and
off-site
problems with ground water, surface
water, air, and food chain contamination. Runoff collection
facilities must
be constructed and monitored. The possible leaching
of
contaminants from the contaminated soil into the ground and groundwater
is a
major concern.
Land Farming incorporates contaminated soil into soil that is
uncontaminated, creating a larger volume of contaminated material.
Therefore,
the rate at which contaminants are degraded must be balanced with the
potential
of creating a larger body of contamination.
Land farms must not be used to dilute contaminants. If it cannot be
shown
that biodegradation
occurs for all contaminants of concern, land farming should not be
used.
Conditions affecting biological degradation of contaminants (e.g.,
temperature, and rainfall) are largely uncontrolled, possibly
increasing the
time to complete remediation.
Inorganic contaminants will not be biodegraded, but they may be
immobilized.
If volatile
organic
compounds (VOCs)
and semi-volatile organic compounds (SVOCs) are
present,
off-gas
(i.e.,
air emissions) control may be required.
Dust control is an important consideration, especially during
tilling
operations.
Many waste constituents may be banned by regulation from being
applied to
soil.
The depth of treatment is limited to the depth of achievable tilling
(normally 18 inches).
A large amount of space is required.
Applicability
Land farming has been proven most successful in treating petroleum hydrocarbons
and other less volatile, biodegradable contaminants. The more
chlorinated or
nitrated the compound, the more difficult it is to degrade. Many mixed
products
and wastes include some volatile components that transfer to the
atmosphere
before they can be degraded. Contaminants that have been successfully
treated
include diesel fuel, No. 2 and No. 6 fuel oils, JP-5 jet fuel, oily sludge,
wood-preserving wastes such as pentachlorophenol
(PCP), polynuclear
aromatic hydrocarbons (PAHs), and creosote),
and
certain pesticides.
Technology Development Status
Numerous full-scale operations have been conducted, particularly for
sludges
produced by the petroleum industry. Land farming is considered a
commercial
technology.
Web Links
http://www.frtr.gov/matrix2/section4/4_13a.html
Other Resources and Demonstrations
None have been identified.