United States
Environmental Protection
Agency
Office of Water
Washington, D.C.
EPA 832-F-00-064
September 2000
&EPA Biosolids
Technology Fact Sheet
Land Application of Biosolids
DESCRIPTION
Biosolids are primarily organic materials produced
during wastewater treatment which may be put to
beneficial use. An example of such use is the
addition of biosolids to soil to supply nutrients and
replenish soil organic matter. This is known as land
application. Biosolids can be used on agricultural
land, forests, rangelands, or on disturbed land in
need of reclamation.
Recycling biosolids through land application serves
several purposes. It improves soil properties, such
as texture and water holding capacity, which make
conditions more favorable for root growth and
increases the drought tolerance of vegetation.
Biosolids application also supplies nutrients
essential for plant growth, including nitrogen and
phosphorous, as well as some essential micro
nutrients such as nickel, zinc, and copper.
Biosolids can also serve as an alternative or
substitute for expensive chemical fertilizers. The
nutrients in the biosolids offer several advantages
over those in inorganic fertilizers because they are
organic and are released slowly to growing plants.
These organic forms of nutrients are less water
soluble and, therefore, less likely to leach into
groundwater or run off into surface waters.
There are several methods to apply biosolids. The
selection of the method depends on the type of land
and the consistency of the biosolids. Liquid
biosolids are essentially 94 to 97 percent water with
relatively low amounts of solids (3 to 6 percent).
These can be injected into the soil or applied to the
land surface. Specialized vehicles are used to inject
biosolids into the soil, as shown in Figure 1. These
tankers have hoses leading from the storage tank to
injection nozzles which release the biosolids.
Source: U.S. EPA, 1984.
FIGURE 1 BIOSOLIDS INJECTION
EQUIPMENT
Modified tanker trucks are used for surface
application (Figure 2). Biosolids applied to the land
surface are usually incorporated into the soil with
conventional farm equipment.
It is often economical to reduce the volume of
biosolids prior to transportation or storage. The
amount of water in biosolids can be reduced
through mechanical processes such as draining,
pressing, or centrifuging, resulting in a material
composed of up to 30 percent dry solids. This
material will be the consistency of damp soil.
Dewatered biosolids do not require any specialized
equipment and can be applied with conventional
agricultural equipment, such as manure spreaders
pulled by tractors.
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Source: U.S. EPA, 1986.
FIGURE 2 LIQUID APPLICATION OF
BIOSOLIDS
Figure 3 shows the spraying of biosolids, an
application method primarily used in forested or
reclamation sites. Liquid biosolids are sprayed
from a tank towed by a truck or other vehicle.
The Environmental Protection Agency's 40 CFR
Part 503, Standards for the Use and Disposal of
Sewage Sludge (the Part 503 Rule), requires that
wastewater solids be processed before they are land
applied. This processing is referred to as
"stabilization" and helps minimize odor
generation, destroys pathogens (disease causing
organisms), and reduces vector attraction potential.
There are several methods to stabilize wastewater
solids, including:
• Adjustment of pH, or alkaline stabilization.
• Digestion.
Composting.
Heat drying.
The Part 503 Rule defines two types of biosolids
with respect to pathogen reduction, Class A and
Class B, depending on the degree of treatment the
solids have received. Both types are safe for land
application, but additional requirements are
imposed on Class B materials. These are detailed
in the Part 503 Rule and include such things as
restricting public access to the application site,
limiting livestock grazing, and controlling crop
harvesting schedules. Class A biosolids (biosolids
treated so that there are no detectable pathogens)
are not subject to these restrictions.
In addition to stabilization, the Part 503 Rule sets
maximum concentrations of metals which cannot be
exceeded in biosolids that will be land applied.
These are termed Ceiling Concentrations. Part 503
also establishes Cumulative Pollutant Loading
Rates for eight metals which may not be exceeded
at land application sites. A third set of metals
criteria is also included in Part 503, known as
Pollutant Concentrations. If these concentrations
are not exceeded in the biosolids to be land applied,
the Cumulative Pollutant Loading Rates do not
need to be tracked. Table 1 shows the three sets of
federal limits applicable to biosolids to be land
applied.
Source: U.S. EPA, 1986.
FIGURE 3 APPLICATION OF LIQUID
BIOSOLIDS TO FOREST LAND
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TABLE 1 MAXIMUM METAL CONCENTRATIONS
Metal
Arsenic
Cadmium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
NL = No limit
Source: U.S.
Ceiling Concentration
(mg/kg)
75
85
4,300
840
57
75
420
100
7,500
EPA, 1993 and 1994.
Cumulative Pollutant
Loading Rates (kg/hectare)
41
39
1,500
300
17
NL
420
100
2,800
Pollutant Concentrations
(mg/kg)
41
39
1,500
300
17
NL
420
100
2,800
The term Exceptional Quality is often used to
describe a biosolids product which meets Class A
pathogen reduction requirements, the most stringent
metals limits (Pollutant Concentrations), and vector
attraction reduction standards specified in the Part
503 Rule. Vectors (flies, mosquitoes, rodents,
birds, etc.) Can transmit diseases directly to humans
or play a specific role in the life cycle of a pathogen
as a host. Vector attraction reduction refers to
processing which makes the biosolids less attractive
to vectors thereby reducing the potential for
transmitting diseases. Exceptional Quality
biosolids products are as safe as other agricultural
and horticultural products and may be used without
site restrictions.
APPLICABILITY
Land application is well-suited for managing solids
from any size wastewater treatment facility. As the
method of choice for small facilities, it offers cost
advantages, benefits to the environment, and value
to the agricultural community. However, biosolids
produced by many major metropolitan areas across
the country are also land applied. For example,
biosolids from the Blue Plains Wastewater
Treatment Facility serving the District of Columbia
and surrounding communities in Virginia and
Maryland have been land applied since the plant
began operation in 1930. The cities of
Philadelphia, Chicago, Denver, New York, Seattle,
and Los Angeles all land apply at least part of their
biosolids production.
Land application is most easily implemented where
agricultural land is available near the site of
biosolids production, but advances in transportation
have made land application viable even where
hauling distances are greater than 1,000 miles. For
example, Philadelphia hauls dewatered biosolids
250 miles to reclaim strip-mines in western
Pennsylvania and New York City ships some of its
biosolids over 2,000 miles to Texas and Colorado.
ADVANTAGES AND DISADVANTAGES
Land application offers several advantages as well
as some disadvantages that must be considered
before selecting this option for managing biosolids.
Advantages
Land application is an excellent way to recycle
wastewater solids as long as the material is quality-
controlled. It returns valuable nutrients to the soil
and enhances conditions for vegetative growth.
Land application is a relatively inexpensive option
and capital investments are generally lower than
other biosolids management technologies.
Contractors can provide the necessary hauling and
land application equipment. In addition, on-site
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spatial needs can be relatively minor depending on
the method of stabilization selected.
Disadvantages
Although land application requires relatively less
capital, the process can be labor intensive. Even if
contractors are used for application, management
oversight is essential for program success. Land
application is also limited to certain times of the
year, especially in colder climates. Biosolids
should not be applied to frozen or snow covered
grounds, while farm fields are sometimes not
accessible during the growing season. Therefore, it
is often necessary to provide a storage capacity in
conjunction with land application programs. Even
when the timing is right (for example, prior to crop
planting in agricultural applications), weather can
interfere with the application. Spring rains can
make it impossible to get application equipment
into farm fields, making it necessary to store
biosolids until weather conditions improve.
Another disadvantage of land application is
potential public opposition, which is encountered
most often when the beneficial use site is close to
residential areas. One of the primary reasons for
public concern is odor. In worst case situations,
municipalities or counties may pass ordinances
which ban or restrict the use of biosolids. However,
many successful programs have gained public
support through effective communications, an
absolutely essential component in the beneficial use
of biosolids.
Environmental Impacts
Despite many positive impacts to the environment,
land application can have negative impacts on
water, soil, and air if not practiced correctly.
Negative impacts to water result from the
application of biosolids at rates that exceed the
nutrient requirements of the vegetation. Excess
nutrients in the biosolids (primarily nitrogen
compounds) can leach from the soil and reach
ground water. Runoff from rainfall may also carry
excess nutrients to surface water. However,
because biosolids are a slow release fertilizer, the
potential for nitrogen compounds to leach from
biosolids amended soil is less than that posed by the
use of chemical fertilizers. In areas fertilized by
either biosolids or chemicals, these potential
impacts are mitigated by proper management
practices, including the application of biosolids at
agronomic rates (the rate nutrients are used by the
vegetation.) Maintenance of buffer zones between
application areas and surface water bodies and soil
conservation practices will minimize impacts to
surface water.
Negative impacts to soil can result from
mismanagement of a biosolids land application.
Federal regulations contain standards related to all
metals of concern and application of biosolids
which meets these standards should not result in the
accumulation of metals to harmful levels. Stringent
record keeping and reporting requirements on both
the federal and state level are imposed to prevent
mismanagement.
Odors from biosolids applications are the primary
negative impact to the air. Most odors associated
with land application are a greater nuisance than
threat to human health or the environment. Odor
controls focus on reducing the odor potential of the
biosolids or incorporating them into the soil.
Stabilization processes such as digestion can
decrease the potential for odor generation.
Biosolids that have been disinfected through the
addition of lime may emit ammonia odors but they
are generally localized and dissipate rapidly.
Biosolids stabilization reduces odors and usually
results in an operation that is less offensive than
manure application.
Overall, a properly managed biosolids land
application program is preferable to the use of
conventional fertilizers for the following reasons:
Biosolids are a recycled product, use of
which does not deplete non-renewable
resources such as phosphorous.
• The nutrients in biosolids are not as soluble
as those in chemical fertilizers and are
therefore released more slowly.
• Biosolids appliers are required to maintain
setbacks from water resources and are often
subject to more stringent soil conservation
and erosion control practices, nutrient
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management, and record keeping and
reporting requirements than farmers who
use only chemical fertilizers or manures.
• Biosolids are closely monitored.
• The organic matter in biosolids improves
soil properties for optimum plant growth,
including tilth, friability, fertility and water
holding capacity. They also decrease the
need for pesticide use.
A joint policy statement of the U.S. Department of
Agriculture, the U.S. Food & Drug Administration,
and the U.S. Environmental Protection Agency
states, "...the use of high quality biosolids coupled
with proper management procedures, should
safeguard the consumer from contaminated crops
and minimize any potential adverse effect on the
environment" (U.S. EPA, 1981).
DESIGN CRITERIA
Design criteria for land application programs
address issues related to application rates and
suitable sites. Design criteria for physical facilities
(such as stabilization) that are part of land
application programs are discussed in separate fact
sheets. Biosolids, site, and vegetative characteristics
are the most important design factors to consider.
Biosolids must meet regulatory requirements for
stabilization and metals content. In addition,
nutrient content and physical characteristics, such
as percent solids, are used to determine the
appropriate application rate for the crop that will be
grown and the soil in which the crops will be
grown.
Site suitability is determined based on such factors
as soil characteristics, slope, depth to groundwater,
and proximity to surface water. In addition, many
states have established site requirements to further
protect water quality. Some examples include:
Sufficient land to provide areas of non-
application (buffers) around surface water
bodies, wells, and wetlands.
• Depth from the soil surface to groundwater
equal to at least one meter.
• Soil pH in the range of 5.5 to 7.5 to
minimize metal leaching and maximize
crop growing conditions.
Site suitability is also influenced by the character of
the surrounding area. While odors and truck traffic
many not be objectionable in an agricultural area,
both will adversely impact residential developments
and community centers close to fields where
biosolids are applied.
The type of vegetation to be grown is also a design
consideration. Vegetation, like soil characteristics,
will generally not exclude biosolids application
since most vegetation will benefit from the practice.
However, the type of vegetation will impact the
choice of application equipment, the amount of
biosolids to be applied, and the timing of
applications. The effect of vegetation on the choice
of application equipment is discussed above in the
description of this technology. The amount of
biosolids that may be applied to a site is a function
of the amount of nutrients required by the
vegetation and the amount of metals found in the
biosolids. Table 2 summarizes the application
frequency, timing, and rates for various types of
sites.
Another factor to be considered in designing a land
application program is the timing of applications.
Long periods of saturated or frozen ground limit
opportunities for application. This is an important
consideration in programs using agricultural lands;
applications must be performed at times convenient
Typical Biosolids Application Rate Scenario
The recommended minimum amount of nitrogen
needed by a typical corn crop to be grown in New
Jersey is 120 pounds per acre per year.
Biosolids containing 3 percent nitrogen could be
applied at up to 5.4 dry tons per acre if used to
supply all the nitrogen needed by the crop (i.e.,
no other nitrogen fertilizers used.) A city
producing 10 dry tons of biosolids per day would
require access to almost 700 acres of corn. If the
biosolids contained only 1.5 percent nitrogen,
twice as many tons could be applied per acre,
requiring only half as many acres to land apply
the same amount of biosolids generated.
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TABLE 2 TYPICAL BIOSOLIDS APPLICATION SCENARIOS
Type of Site/Vegetation
Agricultural land
Corn
Small grains
Soybeans
Hay
Forest land
Range land
Reclamation sites
Schedule
April, May, after harvest
March-June, August, fall
April-June, fall
After each cutting
Year round
Year round
Year round
Application Frequency
Annually
Up to 3 times per year
Annually
Up to 3 times per year
Once every 2 - 5 years
Once every 1 - 2 years
Once
Application Rate
5 to 1 0 dry tons per acre
2 to 5 dry tons per acre
5 to 20 dry tons per acre
2 to 5 dry tons per acre
5 to 1 00 dry tons per acre
2 to 60 dry tons per acre
60 to 100 dry tons per acre
Source: U.S. EPA, 1994.
to the fanner and must not interfere with the
planting of crops. Most application of biosolids to
agricultural land occurs in the early spring or late
fall. As a result, storage or an alternate biosolids
management option must be available to handle
biosolids when application is not possible. Forest
lands and reclamation sites allow more leeway in
the timing of applications. In some areas of the
United States, application can proceed year round.
Application is most beneficial on agricultural land
in late fall or early spring before the crop is planted.
Timing is less critical in forest applications when
nutrients can be incorporated into the soil
throughout the growing period. Winter application
is less desirable in many locales. Rangelands and
pasturelands also are more adaptable to applications
during various seasons. Applications can be made
as long as ground is not saturated or snow covered
and whenever livestock can be grazed on alternate
lands for at least 30 days after the application. The
timing of single applications in land reclamation
programs is less critical and may be dictated by
factors such as regulatory compliance schedules.
PERFORMANCE
In 1995, approximately 54 percent of wastewater
treatment plants managed biosolids through land
application, an increase of almost 20 percent from
information reported in 1993 (WEF, 1997 and U.S.
EPA, 1993.) The vast majority of these land
application programs use agricultural land, with
minor amounts applied to forest lands, rangelands,
or land in need of reclamation.
The use of land application increased steadily in the
1980s for several reasons, including decreasing
availability and increasing costs associated with
landfill disposal. Research also helped refine
procedures for proper land application. Meanwhile,
implementation of the Nationwide Pretreatment
Program resulted in significant improvements in
biosolids quality. The 1993 adoption of the Part
503 Rule created a structure for consistent
application procedures across the nation. The
regulations were developed with input from the
U.S. Department of Agriculture, the U.S. Food and
Drug Administration, biosolids generators,
environmental groups, the public, state regulators,
and academic researchers. Conservative
assumptions were used to create regulations to
"protect public health and the environment from all
reasonably anticipated adverse effects" (U.S. EPA,
1993).
Land application is a reliable biosolids management
option as long as the system is designed to address
such issues as storage or alternate management for
biosolids during periods when application cannot
take place due to unfavorable weather or field
conditions. Public opposition rather than technical
constraints is the most common reason for
discontinuing land application programs.
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"/n fact, in all the years that properly treated biosolids
have been applied to the land, we have been unable
to find one documented case of illness or disease
that resulted."
Martha Prothro, Former Deputy Assistant
Administrator for Water, U.S. Environmental
Protection Agency.
Source: Water Environment Web, 1998.
OPERATION AND MAINTENANCE
Land application systems generally use
uncomplicated, reliable equipment. Operations
include pathogen reduction processing, dewatering,
loading of transport vehicles, transfer to application
equipment, and the actual application. Operations
and maintenance considerations associated with
pathogen reduction processing are discussed in
other fact sheets. The other operations require labor
skills of heavy equipment operators, equipment
maintenance personnel, and field technicians for
sampling, all normally associated with wastewater
treatment facilities.
In addition, the biosolids generator is responsible
for complying with state and local requirements as
well as federal regulations. The biosolids manager
must be able to calculate agronomic rates and
comply with record keeping and recording
requirements. In fact, the generator and land
applier must sign certification statements verifying
accuracy and compliance. The generator should
also allocate time to communicate with farmers,
landowners, and neighbors about the benefits of
biosolids recycling. Control of odors, along with a
viable monitoring program, is most important for
public acceptance.
COSTS
It is difficult to estimate the cost of land application
of biosolids without specific program details. For
example, there is some economy of scale due to
large equipment purchases. The same size machine
might be needed for a program that manages 10 dry
tons of biosolids per day as one managing 50 dry
tons per day; the cost of that machine can be spread
over the 10 or 50 dry tons, greatly affecting average
costs per dry ton. One source identified costs for
land application varying from $60 to $290 per dry
ton (O'Dette, 1996.) This range reflects the wide
variety in land application methods as well as
varying methods to prepare biosolids for land
application. For example, costs for programs using
dewatered biosolids include an additional step
whereas costs for programs using liquid biosolids
do not reflect the cost of dewatering. They do,
however, include generally higher transportation
costs.
Despite the wide range of costs for land application
programs, several elements must be considered in
estimating the cost of any biosolids land application
program:
Purchase of application equipment or
contracting for application services.
Transportation.
Equipment maintenance and fuel.
• Loading facilities.
• Labor.
Capital, operation and maintenance of
stabilization facilities.
• Ability to manage and control odors.
Dewatering (optional).
Storage or alternate management option for
periods when application is not possible due
to weather or climate.
• Regulatory compliance, such as permit
applications, site monitoring, and biosolids
analyses.
• Public education and outreach efforts.
Land must also be secured. Some municipalities
have purchased farms for land application; others
apply biosolids to privately held land.
Some operating costs can be offset through the sale
of the biosolids material. Since the biosolids
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reduce the need for fertilizers and pH adjustment,
farmers sometimes pay to have biosolids applied to
their lands.
REFERENCES
Other Related Fact Sheets
Odor Management in Biosolids Management
EPA 832-F-00-067
September 2000
Centrifugal Dewatering/Thickening
EPA 832-F-053
September 2000
Belt Filter Press
EPA 832-F-00-057
September 2000
Filter Press, Recessed Plate
EPA 832-F-00-058
September 2000
Alkaline Stabilization of Biosolids
EPA 832-F-00-052
September 2000
Other EPA Fact Sheets can be found at the
following web address:
http://www.epa.gov/owmitnet/mtbfact.htm.
1. O'Dette, R.G., 1996. Determining the Most
Cost Effective Option for Biosolids and
Residuals Management. In Proceedings of
the 10th Annual Residuals and Biosolids
Management Conference: 10 Years of
Progress and a Look Toward the Future.
Alexandria. Water Environment Federation.
2. Sopper, W.E., Seaker, E.M., and Bastian,
R.K., Editors, 1982. Land Reclamation and
Biomass Production and Municipal
Wastewater and Sludge. University Park.
The Pennsylvania State University Press.
7.
9.
10.
U.S. Environmental Protection Agency,
1995. Amendments to the Standards for the
Use or Disposal of Sewage Sludge (40 Code
of Federal Regulations Part 503).
Washington, D.C. U.S. Environmental
Protection Agency.
U.S. Environmental Protection Agency,
1994. Biosolids Recycling: Beneficial
Technologies for a Better Environment.
EPA 832-R-94-009. Washington, D.C.
U.S. Environmental Protection Agency,
Office of Water.
U.S. Environmental Protection Agency,
1993. Standards for the Use or Disposal of
Sewage Sludge (40 Code of Federal
Regulations Part 503). Washington, D.C.
U.S. Environmental Protection Agency.
U.S. Environmental Protection Agency,
1991. National Pretreatment Program:
Report to Congress (EPA 21 W-4004.).
Washington, D.C. U.S. Environmental
Protection Agency.
U.S. Environmental Protection Agency,
1986, Sewage Sludge Management Primer,
Technology Transfer Series. Cincinnati.
U.S. Environmental Protection Agency.
U.S. Environmental Protection Agency,
1984. Environmental Regulations and
Technology, Use and Disposal of Municipal
Wastewater Sludge (EPA 625/10-84-003.)
Cincinnati. U.S. Environmental Protection
Agency.
U.S. Environmental Protection Agency,
1983. Process Design Manual Land
Application of Municipal Sludge (EPA
625/1-83-016.) Cincinnati. U.S.
Environmental Protection Agency.
U.S. Environmental Protection Agency,
1981. Inter agency Policy on Beneficial Use
of Municipal Sewage Sludge. Washington,
D.C. U.S. Environmental Protection
Agency.
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11. Water Environment Federation, 1997.
National Outlook - State Beneficial Use of
Biosolids Activities. Washington, D.C.
Water Environment Federation.
12. Water Environment Web,
http://www.wef.org/doc/bioquotes.html,
Septembers, 1998.
13. Water Quality Management Library, 1992.
Municipal Sewage Sludge Management-
Processing, Utilization and Disposal, ed.
Cecil Lue-Hing, David R. Zenz, Richard
Kuchenrither. Lancaster. Technomic
Publishing Company, Inc.
ADDITIONAL INFORMATION
Cecil Lue-Hing & Associates, Inc.
Cecil Lue-Hing
6101 N. Sheridan Street, 40B East
Chicago, IL 60660
Denver Metro Wastewater Reclamation District
Steve Frank
6450 York Street
Denver, CO 80229
District of Columbia Water and Sewer Authority
Chris Peot
5000 Overlook Avenue, S.W.
Washington, D.C. 20032
Forste Associates
Jane Forste
897 Laurel Way
Arnold, MD 21012
The mention of trade names or commercial
products does not constitute endorsement or
recommendations for use by the United States
Environmental Protection Agency (EPA).
For more information contact:
Municipal Technology Branch
U.S. EPA
Mail Code 4204
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
IMTB
Excellence h compliance through optfrnal technical solutfons
MUNICIPAL TECHNOLOGY BRANCH
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