Typical Land Treatment Unit
Land Treatment is a full-scale bioremediation technology in which
contaminated soils, sediments, or sludges are turned over (i.e., tilled) and allowed to
interact with the soil and climate at the site. The waste, soil, climate, and biological
activity interact dynamically as a system to degrade, transform, and immobilize waste
constitutes. Wastes are periodically tilled to aerate the waste.
Soil conditions are
often controlled to optimize the rate of contaminant degradation. Conditions normally
- Moisture content (usually by irrigation or spraying).
- Aeration (by tilling the soil with a predetermined frequency, the soil is mixed and
- pH (buffered near neutral pH by adding crushed limestone or agricultural lime).
- Other amendments (e.g., Soil bulking agents, nutrients, etc.).
A Land Treatment site must be managed properly to prevent both on-site and off-site
problems with ground water, surface water, air, or food chain contamination. Adequate
monitoring and environmental safeguards are required.
Land Treatment is a medium- to long-term technology.
Solid phase treatment; Landfarming; Land application, Land
DSERTS Code: H15 (Land Treatment).
Soil bioremediation has been proven most successful in treating petroleum
hydrocarbons and other less volatile, biodegradable contaminants. Because lighter, more
volatile hydrocarbons such as gasoline are treated very successfully by processes that use
their volatility [i.e., soil vapor (vacuum) extraction and bioventing], the use of
aboveground bioremediation is usually limited to heavier hydrocarbons. As a rule of thumb,
the higher the molecular weight (and the more rings with a PAH), the slower the
degradation rate. Also, the more chlorinated or nitrated the compound, the more difficult
it is to degrade. (Note: 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, oily
sludge, wood-preserving wastes (PCP, PAHs, and creosote), coke wastes, and certain
Factors that may limit the applicability and effectiveness of the process
- A large amount of space is required.
- Conditions affecting biological degradation of contaminants (e.g., temperature, rain
fall) are largely uncontrolled, which increases the length of time to complete
- Inorganic contaminants will not be biodegraded.
- Volatile contaminants, such as solvents, must be pretreated because they would evaporate
into the atmosphere, causing air pollution.
- Dust control is an important consideration, especially during tilling and other material
- Presence of metal ions may be toxic to the microbes and possibly leach from the
contaminated soil into the ground.
- Runoff collection facilities must be constructed and monitored.
- Topography, erosion, climate, soil stratigraphy, and permeability of the soil at the
site must be evaluated to determine the optimum design of facility.
- Waste constitutes may be subject to "Land-ban" regulation and thus may not be
applied to soil for treatment by land treatment (e.g., some petroleum sludges).
- The depth of treatment is limited to the depth of achievable tilling (normally 18
A detailed discussion of these data elements is provided in Subsection 2.2.1 (Data Requirements for Soil, Sediment,
and Sludge). The following contaminant considerations should be addressed prior to
implementation: types and concentrations of contaminants, depth profile and distribution
of contaminants, presence of toxic contaminants, presence of VOCs, and presence of
inorganic contaminants (e.g., metals).
The following site and soil considerations should
be addressed prior to implementation: surface geological features (e.g., topography and
vegetative cover), subsurface geological and hydrogeological features, climate,
precipitation, wind velocity and direction, water availability, soil type and texture,
soil moisture content, soil organic matter content, cation exchange capacity,
water-holding capacity, nutrient content, pH, permeability, and microorganisms
(degradative populations present at site).
In some cases, the presence of co-contaminants, that is contaminants which are not the
primary contaminants of concern, may have appreciable effects on land treatment.
Ecotoxicity tests may also be helpful in characterizing the performance of land treatment
Numerous full-scale operations have been used, particularly for sludges
produced by the petroleum industry. As with other biological treatments, under proper
conditions, land treatment can transform contaminants into nonhazardous substances.
Removal efficiencies, however, are a function of contaminant type and concentrations, soil
type, temperature, moisture, waste loading rates, application frequency, aeration,
volatilization, and other factors.
Ranges of costs likely to be encountered are:
- Costs prior to treatment (assumed to be independent of volume to be treated): $25,000 to
$50,000 for laboratory studies; about $100,000 for pilot tests or field demonstrations.
- Cost of land treatment: $30 to $70 per cubic meter ($25 to $50 per cubic yard).
California Base Closure Environmental Committee (CBCEC), 1994. Treatment
Technologies Applications Matrix for Base Closure Activities, Revision 1,
Technology Matching Process Action Team, November, 1994.
EPA, 1990. Bioremediation
in the Field, EPA/540/2-90-004.
Federal Remediation Technologies Roundtable, 1995. Remediation Case
Studies: Bioremediation, EPA/542/R-95/002.
Federal Remediation Technologies Roundtable, 1997. Remediation Case
Studies: Bioremediation and Vitrification, EPA/542/R-97/008.
Federal Remediation Technologies Roundtable, 1998. Remediation Case
Studies: Ex Situ Soil Treatment Technologies (Bioremediation and Vitrification),
Norris, et al., 1994. Handbook of Bioremediation, EPA,
RSKERL, Lewis Publishers, CRC Press, 200 Corporate Boulevard, Boca Raton, FL 33431.
Pope, D.F. and J.E. Matthews, 1993. Bioremediation Using the Land Treatment
Concept, EPA Report EPA/600/R-93/164.
Sims, J.L., et al., 1989. Bioremediation of Contaminated Surface Soils,
EPA, RSKERL, EPA Report EPA/600/9-89/073.
USACE, 1996. Champion International Superfund Site, Libby, Montana:
Bioremediation Field Performance Evaluation of the Prepared Bed Land Treatment Systems, EPA/600/R-95/156.
USACE, 1996. Bioremediation Using Landfarming Systems,
Engineering Technical Letter (ETL), ETL 1110-1-176.
USACE, 1996. Bioremediation Using Landfarming Systems, USACE
Guide Specification, CEGS 02287.
Points of Contact:
General FRTR Agency
Technology Specific Web Sites:
Government Web Sites
A list of vendors offering In
Situ Biological Treatment is available from the Vendor Information System for
Innovative Treatment Technologies (VISITT) developed
by U.S. Environmental Protection Agency (EPA).
Health and Safety: