oEPA
United States
Environmental Protection
Agency
Office of Water October 1982
Program Operations (WH-547) 430/9-82-008
Washington DC 20460
SLUDGE
Recycling
For Agricultural Use
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This brochure was prepared for the U.S. EPA Office of Water Program
Operations as one of a series of reports to help supply information concerning
current practices that are emphasized by the Clean Water Act (CWA)
involving the utilization and recycling of municipal effluents and sludges The
series will provide planners, designers, municipal engineers, environmental-
ists and others with available information on topics of major interest and
concern related to municipal wastewater treatment and sludge management
options. An effort will be made to provide the most current state-of-the-art
information available concerning sewage and sludge processing and disposal/
utilization alternatives, as well as costs, transport, and environmental and
health impacts. The mention of trade names of commercial products does not
constitute endorsement or recommendation for use.
This report provides an insight into how several communities have success-
fully developed sludge management programs that involve the recycling of
municipal sludge for agricultural use. As stated in the provisions of both the
CWA and the Resource Conservation and Recovery Act (RCRA), the Agency en-
courages the recycling of municipal sludge for many uses, including agricultural
use, where good quality sludges and good management practices are employed
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Foreword
What to do with increasing volumes
of sewage sludge is a problem currently
being faced by many municipalities.
This situation has arisen as a direct
result of efforts to clean up our nation's
surface waters. The establishment of
both Federal and state wastewater
treatment requirements and recent
initiatives to bring sludge disposal
practices under more rigid environ-
mental scrutiny and regulatory control
have also been contributing factors.
The recycling of sewage sludge for
certain agricultural uses is one alterna-
tive to incineration, landfilling and
ocean disposal practices that is receiv-
ing increasing attention. The potential
benefits from recycling the soil-build-
ing and nutrient resources in sewage
sludge by land application have been
well demonstrated and have led to
the utilization of sludges in agriculture
in many areas.
However, the public doubts and
officials' concerns about adding poten-
tially toxic substances and pathogens
found in the sludge to productive
farmlands must also be carefully con-
sidered. Therefore, land application
of sewage sludge to agricultural lands
must still be examined closely in
terms of protection of human health,
crop quality and future land pro-
ductivity.
As a sludge disposal technique,
land application of sewage sludge to
agricultural lands has been practiced
for many years in this country and
overseas. Only in recent years, how-
ever, have the necessary research and
monitoring studies been undertaken
to develop sound design guidelines
for agricultural use of sewage sludge.
Appropriate management practices
have been developed to allow land
application systems to be properly
designed and operated from an envi-
ronmental standpoint, which also
helps assure the long-term productiv-
ity and protection of the lands to
which the sludge is applied. The
various regulations, criteria and guide-
lines being developed under the au-
thorities of the Clean Water Act, the
Resource Conservation and Recovery
Act, and other recent environmental
legislation will help provide the mech-
anisms to better control the imple-
mentation of agricultural recycle
projects as well as other sludge man-
agement alternatives in the future.
While this alternative is faced with
potential public acceptance and envi-
ronmental impact concerns, sludge
management projects that recycle
sewage sludge for agricultural use
can, in many cases, be designed and
operated to be both cost-effective
and environmentally acceptable. This
is especially true for small commu-
nities which have high quality sludges
and are located in areas where ade-
quate farmland is readily available.
The implementation of improved
industrial pretreatment programs
should help to substantially reduce
contaminant concentrations in the
sludge produced at many municipal
wastewater treatment plants and
should further enhance the accept-
ability of recycling even more sewage
sludges for agricultural use.
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Composted municipal sludge.
What is Sludge?
And What Do WP Do With It? C^
Sludge is the residue of materials
removed from wastewater, sometimes
called sewage, during the process of
wastewater treatment. Because of its
origin and the immense quantities in
which it is produced (in excess of 6
million tons of dry solids per year in
the United States alone), it represents
a major handling problem for many
communities. On the other hand,
because it is composed of humus,
nitrogen, and smaller amounts of
phosphorus, potassium and other
trace metals, it also represents an
opportunity for use as an effective
soil conditioner/fertilizer.
Sludge is the residue of
materials from wastewater
treatment...
Viewed as a resource rather than as
a waste, sludge offers significant po-
tential when recycled for agricultural
use. Based on late 1979 prices, the
nitrogen, phosphorus and potassium
value of the United States' municipal
sludge production is about $100 mil-
lion per year.
Sludge Disposal—The
Traditional Approach
For decades, the key word in sludge
handling has been disposal, generally
meaning landfill, incineration or dis-
charge to the ocean. While serving as
effective means for dealing with
sludge, these disposal practices carry
certain inherent disadvantages, mainly
in regard to the environment.
Landfill of sludge, a common meth-
od of disposal, can pose a threat to
groundwaters if the disposal site is
not properly located and managed.
Even under the best of conditions,
existing landfill sites are rapidly being
exhausted. In addition, due to increas-
ing land costs and widespread public
opposition to creation of new landfill
sites, potential new sites are difficult
to obtain and use for landfill purposes.
Incineration can greatly reduce the
volume of sludge. In the past, this
process required tremendous con-
sumption of energy. While newer
incineration systems can be designed
to recover energy and overcome past
problems with excessive fuel require-
ments, they are generally more suit-
able for larger communities, which
can benefit from economies of scale
and can better manage these more
complex systems.
Ocean disposal formerly provided
coastal cities with an economical
sludge disposal system. However, due
to concerns over potential impacts to
the marine environment, today's
ocean disposal practices are being
phased out under state and Federal
laws and regulations.
With many of the traditional sludge
disposal methods limited by land
shortages, cost and environmental
concerns, some communities have
turned from a philosophy of disposal
to one of reuse.
Sludge Reuse—An Alternative
That Makes Sense
By developing and then imple-
menting carefully planned and man-
aged projects, some communities
have been able to realize their goal
of achieving an environmentally
sound, economical answer to the
problem of sludge disposal. They have
done so through land application of
sludge, which has proven advanta-
geous for such uses as reforestation
projects, land reclamation, crop pro-
duction and parkland development.
Why do such programs work?
Mainly because when sludge is spread
on land, natural biological systems
take over, breaking down the sludge
and incorporating its nutrients and
organic matter into the soil. This en-
hances the soil quality while providing
a beneficial use for the sludge.
...the concepts have
turned from disposal
to reuse...
Sludge As Soil Conditioner/Fertilizer
The benefits of recycling municipal
sludges for agricultural use are exten-
sive. Not only does sludge application
help municipalities by acting as a
sludge management technique, it also
serves the farmer by improving soil,
reducing fertilizer costs and increas-
ing crop yields.
Commercial fertilizers are increasing
in price and decreasing in availability;
conversely, sludge is increasing in
availability and can serve as a valuable
soil amendment and fertilizer source.
In this sense, sludge is actually a mis-
placed resource. If properly managed,
it can help lower spiraling wastewater
treatment costs, lower crop produc-
tion costs, and conserve diminishing
supplies of non-renewable resources
such as natural gas, from which many
commercial nitrogen fertilizers are
manufactured.
Major Concerns Over Sludge
Reuse In Agriculture
While the benefits of recycling
municipal sludges for agricultural use
are well documented, a number of
concerns are frequently raised when
projects involving agricultural reuse
are proposed. Primary among the
concerns associated with land appli-
cation of sludge is the possibility of
contaminating the soil with pathogens
or toxic substances that may be pres-
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ent in the sludge. If accumulation of
such contaminants exceeds the soil's
ability to accommodate the input, the
land could be deteriorated rather than
improved, groundwater quality could
be degraded, local surface water
quality could be impacted due to run-
off, or the quality of crops grown
could be adversely affected due to
crop uptake of the contaminants.
University and government re-
searchers across the country have
been developing management prac-
tices to prevent problems from occur-
ring as a result of applying municipal
sludge to cropland. A number of
universities, states and Federal agen-
cies have issued detailed guidance on
the proper use of municipal sludge as
a soil conditioner/fertilizer. Also, the
presence of heavy metals such as
cadmium and lead, and toxic organics
such as PCBs at varying concentra-
tions in different sludges has led EPA
and many state regulatory agencies to
develop guidelines and regulations,
including the Criteria for Classifica-
tion of Solid Waste Disposal Facilities
and Practices (40 CFR Part 257),
aimed at limiting the levels of such
contaminants in sludges applied to
the land. Adherence to the recom-
mendations and requirements that are
issued by the agricultural extension
programs and regulatory agencies
should help assure both safe and
effective recycling of municipal
sludge for agricultural use. By follow-
ing carefully planned procedures for
dispensing the sludge at predetermined
application rates and using good
quality sludges, land application
projects can be implemented and
contamination problems avoided.
Field application vehicle distributing liquid
digested sludge on agricultural land.
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Sludge being transferred from on-farm holding tank
to field application vehicle.
From Treatment Plant
To Farm
Components Of A Successful Sludge Reuse Program
Recycling municipal sludges for agri-
cultural use has been tried, tested and
demonstrated to be a workable solu-
tion for the management of some
sludges. By following the available
guidance and regulations closely,
projects can be established that will
be cost-effective and gain regulatory
agency approval.
But what does it take to put to-
gether a workable sludge/agriculture
program—one that is locally accept-
able and that benefits both the urban
community and the farm community?
This question is examined in the fol-
lowing sections—sections that detail
how sludge reuse in agriculture has
worked successfully for some com-
munities and demonstrate how it may
be able to work for your community.
Raw sludge, the direct product of
wastewater treatment, is an organic/
inorganic material containing live
microorganisms—bacteria and patho-
gens, including some that can cause
disease or produce objectionable
odors. Obviously this is a material
that would usually not be suited for
direct application to agricultural land.
Lacking proper treatment of sludge,
a reuse program would be impossible.
Raw sludge should undergo process-
ing designed to stabilize it and pro-
duce a material that is safe to use and
that will not create odor problems.
Treatment Processes
The most important step in this
necessary processing is one of stabili-
zation to make the treated sludge less
odorous and reduce the pathogenic
organism content. Stabilization can
be accomplished in a variety of ways,
including composting, heat treatment,
digestion and other processes. Among
stabilization processes, digestion is
the most widely used. During diges-
tion, malodorous organic material
contained in sludge is decomposed
through bacterial action. In this
respect, digestion is similar to com-
posting, which can also be used to
stabilize raw sludge.
The most important step is
stabilization.
Stabilization processes achieve two
important results, both of which are
critically necessary prior to land appli-
cation of sewage sludge. First, stabili-
zation breaks down unstable, rapidly
decomposable constituents (princi-
pally organic matter) into smaller
quantities of more stable organic
compounds that, when properly used
in agriculture, will not give rise to
offensive odors. Secondly, stabiliza-
tion processes can achieve high de-
grees of destruction of pathogenic
organisms that are present in raw
sludge, thus rendering the stabilized
sludge much safer for use from the
standpoint of disease transmission.
In addition to stabilization, sludge
may be partially or nearly completely
dried to reduce its moisture content.
Whether or not these additional drying
steps are employed is largely depend-
ent on the manner in which the stabi-
lized sludge will be used. Sludge may
be applied to agricultural land in
either a liquid or a dried form.
Public Education Programs
Reuse of sludge through land appli-
cation requires that the community
where the sludge will be applied be
assured of the safety and value of the
program. In addition, either the mu-
nicipality must purchase land to use
for sludge application or the local
farmers must agree to use the sludge.
Therefore, a municipality pursuing a
program of sludge reuse must work
toward public acceptance of the con-
cept and must locate farmers inter-
ested in using the sludge product.
Education in the form of public
meetings and public information
campaigns is the way that many pro-
grams have approached community
relations. Letting people know and
see what to expect—the disadvantages
as well as the advantages —helps the
communications process and gains
public confidence.
Public education and
awareness are essential.
An extension of the public educa-
tion program has been employed to
let the farming community know what
it has to gain from using the sludge
product. This can take the form of
small-scale demonstrations where
side-by-side comparisons are made
on adjoining plots of land to compare
crop yields both with and without
sludge application. Such demonstra-
tions, when properly carried out (often
through university cooperative exten-
sion programs), can do much to foster
the acceptance of agricultural reuse
of sludge by both the urban commu-
nity that produces the sludge and the
farming community that can use it.
They have also been an effective way
of demonstrating the overall cost-
effectiveness of recycling municipal
sludge for agricultural use in many
locations. This was clearly the case
for the agricultural reuse projects
developed by Salem, Oregon, and
Madison, Wisconsin, described on
the following pages.
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BIOGRO
A well-conceived and implemented
public education program, as well as
a project plan that is acceptable to
the regulatory agencies, can make the
difference between failure and suc-
cess. This is what Salem, Oregon,
discovered as it attempted to find a
solution to its sludge disposal problem.
Salem, Oregon, is an important food
processing center. While this means
that the local economy is thriving and
growing, it also means that the city,
with a population of 89,000, experi-
ences periodic increases in its waste
loads—increases of up to sixfold dur-
ing the months when canning and
freezing operations are in process.
Construction of the Willow Lake
Wastewater Treatment Plant in 1964
and its subsequent expansion in 1976
increased treatment capacity to han-
dle peak flows during the food proc-
essing season as well as normal load-
ings during the balance of the year.
However, the sludge disposal problem
was not solved by increasing treat-
ment capacity.
Sludge Reuse History
Salem continued to discharge sludge
into storage lagoons until 1968, when
the lagoons were within a few years
of reaching their capacity. The city
then began to haul sludge to local
farmland, where it was applied by a
1,400-gallon tank truck. Unfortunately,
the truck tended to become mired in
the fields during western Oregon's
long rainy season. This made for an
inefficient operation because truck
turnaround times were greatly in-
creased, the trucks having to be dis-
lodged from the fields and put back
into service, and the trucking opera-
tion caused undesirable ruts in the
cropland. Furthermore, local residents
mistakenly blamed the sludge opera-
tion for odors originating from other
operations involving the disposal of
livestock manure. Soon it became
difficult to find farmers willing to use
the sludge; this led Salem to reevalu-
ate its program and its system.
Salem's BIOGRO Program
As a first step, a trade name and an
identifiable logo were developed for
Salem's sewage sludge and the city set
about promoting its new product,
BIOGRO. A program manager famil-
iar with local farming and fertilizing
methods was put in charge. With his
background and understanding of the
program, he could relate easily to the
farmers and help them make the best
use of BIOGRO. Meetings were held
to familiarize prospective users with
the program and to obtain their com-
ments on the program. Also, a pro-
motional brochure was prepared and
distributed detailing the benefits of
BIOGRO and explaining how the
program works.
As part of the program revision,
transportation of BIOGRO to the
farms was improved. To correct the
problems encountered during wet
seasons, the city limited delivery of
large quantities of BIOGRO to the
drier months.
The flow rate at Salem's Willow
Lake Wastewater Treatment Plant
averages 28 million gallons per day
(mgd). Because of the large input of
food processing waste and the ab-
sence of other significant industrial
input, sludge production and quality
are very high, averaging 7,800 tons per
year of stabilized BIOGRO at a 2 per-
cent to 3 percent solids concentration.
This sludge product contains useful
quantities of primary and micronu-
trients that are essential for healthy
plant growth.
Application of BIOGRO to the farm-
land is accomplished using 2,500-
gallon truck spreaders equipped with
special high flotation tires to minimize
soil compaction. These spreaders,
easily identified by the BIOGRO logo,
dispense BIOGRO in a 10- to 30-foot-
wide swath by pumping at low pres-
sure. A typical application requires
about five tankloads of liquid BIOGRO
to produce the equivalent of two dry
tons of stabilized sludge per acre
of land.
Public education has played an
important role in alleviating the con-
fusion about odor and BIOGRO.
People in the area now know that
BIOGRO has an odor similar to that
of tar or used engine oil, not sewage
or animal manure. This odor disap-
pears rapidly after application and
can be avoided by disking BIOGRO
into the soil. Therefore, BIOGRO is
no longer blamed for objectionable
odors from other sources.
Other considerations involved in
BIOGRO use are its relatively low
potash content, potential inhibition
of seed germination due to initially
high levels of ammonia and salts, and
viable seeds of unwanted plants such
as tomatoes and melons, which are
frequently contained in the stabilized
sludge. These problems can be over-
come by adding supplemental potash
fertilizer, planting of seeds at least
one week after application of BIOGRO,
and normal cultivation practices for
weed control.
An intensive program of monitoring
and recordkeeping has further con-
vinced both farmers and local resi-
dents of the safety of BIOGRO use.
This information is valuable to the
farmers, who are able to keep track
of crop performance, and to the con-
cerned regulatory agencies responsible
for preserving the quality of crops',
groundwater and the soil.
On an overall basis, then, BIOGRO
has been accepted as a safe, effective
fertilizer supplement and has been
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welcomed by the farmers of the
Salem area. In addition, after five
years of consistent use and careful
testing of sludge, soils, crops and
groundwater, no harmful or undesir-
able effects associated with the use
of BIOCRO have been found.
BIOGRO As A Solution
For the city, application of BIOGRO
to cropland is not the total answer to
sludge management. The growing
season in the Salem area ranges from
160 to 210 days per year. While mean
temperatures are mild, averaging
45° F during the winter or rainy sea-
son, the six-month-long (October
through March) rainy season means
that there will be times when BIOCRO
cannot be applied and must, there-
fore, be stored. Digesters employed
for stabilization at Salem provide
60 days' storage to meet this need; an
additional 100 days of emergency
storage is available in sludge lagoons.
Initial reaction to BIOGRO and the
accompanying program was enthu-
siastic—so much so that, at times,
there was a BIOCRO shortage when
demand surpassed supply. Due to
present equipment availability and
recent large increases in sludge pro-
duction at Salem, it is difficult to
transport and apply all of the current
sludge production to farmland on a
timely basis. No lack of demand for
BIOGRO exists, however, and the
problem can be readily solved through
the purchase of additional transport
and application equipment.
Only a few short years ago, Salem,
which at that time had less than half
as much sludge to deal with as they
have today, was looking at a major
sludge disposal problem. Today,
through a cooperative effort involving
both the city and local farmers, what
used to be thought of as a waste
product has been transformed into an
asset which, used in an economically
and environmentally sound way, ben-
efits the entire area. This, perhaps, is
the true measure of BIOGRO's success.
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A project involving the recycling of high quality
municipal sludge for agricultural use begins at
a wastewater treatment plant, where the
sludge is produced as a byproduct of wastewater
treatment. Following adequate digestion or
stabilization, the material is transported (1) to the
farm fields, where it is applied (2), frequently by
direct incorporation into the soil (3). Sludges are
often composted (4) prior to application to
agricultural land, parkland, reclamation sites and
other areas. In any case, monitoring of the sludge
quality and application site (5 and 6) is an essential
part of any such sludge reuse program. Through
the continued use of well-managed sludge recycling
programs, the valuable nutrients and soil con-
ditioning properties of many municipal sludges can
be effectively recycled for agricultural use.
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METROGRO
Some 1,700 miles east of Salem is
another state capital—Madison, Wis-
consin, population 173,000, almost
twice that of Salem. In Madison, the
winters are longer and harsher than
in Salem (the average mean winter
temperature is 24° F) and the growing
season is about a month shorter.
There, snow cover during the winter
months is common, and the ground
normally remains frozen until mid-
March, whereas in Salem snow cover
and frozen ground conditions are rare.
But in some ways, these two cities are
alike. Both have a history of sludge
reuse, and both now have highly suc-
cessful recycling programs in operation.
In Madison, Wisconsin, sludge
reuse dates back to the early 1930s,
when dewatered digested sludge was
sold or given to the public for fertiliz-
ing lawns and gardens. The manpower
shortage created by World War II
meant that this reuse program had to
be abandoned in favor of low-cost,
low-maintenance storage lagoons.
However, in the early 1970s, these
storage lagoons experienced a number
of dike failures that convinced the
city that a more reliable method of
sludge disposal had to be found.
Studies And Decisions
Several studies carried out between
1971 and 1974 helped Madison deter-
mine that land application of liquid
digested sludge would be a possible
answer to their sludge disposal prob-
lem. In comparison to other methods
of sludge handling—incineration,
composting and mechanical dewater-
ing—land application was shown to
be more economical and more feasible
from both technical and environmen-
tal standpoints.
One of Madison's major decisions
in pursuing a land application pro-
gram involved selection of the type
of land to be used. Should the city
operate its own agricultural site or
distribute the sludge to local farms?
Reuse by farmers can have
advantages over a munic-
ipally owned system.
The main advantages of using city-
owned land were identified as ready
access to and complete operational
control of a reliable sludge disposal
site. The potential disadvantages for
Madison included costly purchase of
a large amount of land; the need to
condemn and, therefore, remove from
the tax rolls existing farmland owned
by local farmers for generatjons; and
competition with the local farm com-
munity through marketing of crops.
The disadvantages of public own-
ership of land far outweighed the
potential advantages; so Madison
decided to try to market its sludge to
area farmers.
Madison's METROGRO Program
The flow rate at Madison's waste-
water treatment plant averages 35 mgd,
producing almost 5,500 tons per year
of stabilized sludge. Almost 15 per-
cent of the total influent organic
loading at the plant is from meat
processing and packing operations.
Madison's wastewater is therefore
high in protein, and the resultant
sludge is attractive as a soil supple-
ment because of its organic and
mineral contents.
Much like its counterpart in Salem,
Madison's program incorporates pub-
lic meetings, efficient delivery systems,
intense monitoring and recordkeeping.
Madison even has its own trade name
for its sludge product—METROGRO.
One big difference between the two
programs, however, is the effect of
weather. Madison's winters result in
frozen ground to a depth of 20 inches
from mid-December through mid-
March. This means that the sludge
application period in Madison is
limited. Their equipment cannot
effectively operate on wet or soft
soil that occurs in late spring and
early fall, and the sludge is not applied
to snow-covered ground.
Like Salem, provisions for storage
at Madison have solved this problem.
One of the city's lagoons is used for
temporary storage; therefore, even
though sludge production continues
throughout the year, Madison's pro-
gram is not jeopardized by the sea-
sonal periods when sludge application
is difficult.
METROGRO is distributed in the
Madison area by 3,500-gallon applica-
tion vehicles equipped with flotation
tires. These truck spreaders apply
METROGRO on the soil surface or
inject it below the surface. Madison
supplies all of the labor and equip-
ment needed to dispense the METRO-
GRO; everything necessary to make
the METROGRO program a success
has been made part of Madison's effort.
The return on Madison's investment
of time and planning has been a
program that works... a program that
links city and farm in the cycle of
nature.
Injectors used at Madison place METROCRO
beneath the soil surface.
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Organic solids reuse manager (left) for Madison's
reuse program discussing crop performance with a
Madison-area farmer who uses METROCRO.
Before deciding on the specifics of
its own land application program,
Madison reviewed the state-of-the-art
of sludge reuse as demonstrated by
existing programs in the United States
and Great Britain. What Madison
learned supported their plan to initi-
ate such a program and provided some
of the facts needed to determine how
best to approach the overall planning
process.
Below is an overview of two of the
programs Madison investigated along
with an update on the present direc-
tion of sludge reuse programs.
Great Britain
The program developed by the
West Hertfordshire Main Drainage
Authority in Rickmansworth, Great
Britain, has been an important pio-
neering effort in sludge reuse. It wasn't
always so, however. A 1,200-acre
demonstration project sponsored by
the Authority failed to gain farmer
acceptance of sludge as a fertilizer
until the Authority decided to develop
a marketing program.
The marketing program was geared
toward improving public relations.
Included were creation of a trade
name for the Authority's product,
HYDIG; publication of a pamphlet
describing HYDIG and its uses and
benefits as a fertilizer; institution of
an extensive monitoring program;
emphasis on clean, efficient trucking
and spreading services; and reshaping
of the image and function of the
HYDIG truckdrivers, who are expected
to assist the farmer while acting as
ambassadors of the Authority. In
addition, an advisory board of farmers
was established by the Authority to
help develop policies and set charges
for the landspreading service.
These public relations elements
resulted in a successful program, one
that enabled the Authority to manage
all of its sludge by application to pri-
vately owned farmlands while real-
izing a savings of about 75 percent
over the cost of ocean disposal, which
still remains the major means of sludge
disposal in Great Britain.
Sludge application to agricultural
land has also been extensively utilized
elsewhere in Great Britain and in other
countries such as France, Germany,
Sweden and the Netherlands.
Los Angeles County Sanitation
Districts, California
A different approach to sludge
reuse has been used to market some
of the digested sludge resulting from
wastewater treatment provided by the
Los Angeles County Sanitation Dis-
tricts. In this major population center,
in excess of 100 tons of solids per day
are composted after stabilization by
digestion. The compost thus produced
is sold to a local fertilizer company
that further processes the material
through screening and blending. The
material is then bagged and marketed
as a fertilizer and is widely used for
home garden and horticultural pur-
poses as well as commercial nurseries.
Demand for the product is so high
that the fertilizer company has to
allocate it to selected customers. This
sludge-derived product has been
marketed to the public for over 50
years by this same firm.
Current Sludge Agricultural
Reuse Programs
In addition to the BIOGRO and
METROGRO programs described for
Salem and Madison, a large number
of other agricultural reuse programs
are now in use in many parts of the
United States, especially in the smaller
towns of the Midwest. Agricultural
reuse programs are currently being
used or evaluated by large cities-
such as Philadelphia, Pennsylvania;
Washington, D.C.; Chicago, Illinois;
Columbus and Toledo, Ohio; and
Denver and Boulder, Colorado —as
well as by smaller towns such as
Binghamton, New York; Effingham,
Illinois; Manhattan, Kansas; and Little
Falls, Minnesota.
It is estimated that well over 25 per-
cent of the nation's sewage sludge is
presently utilized in land application
projects and that most of these proj-
ects involve application to cropland.
As the costs of alternative sludge
management practices continue to
rise and sludge quality improves
through more intensive implementa-
tion of pretreatment programs, even
more agricultural reuse programs can
be expected to be developed.
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The Facts
Operating And Performance Features Of Sludge Reuse
The scope of a particular sludge reuse
program will determine the equip-
ment and personnel needs and, there-
fore, the costs of such a program. A
major factor in determining the scope
is the quantity of sludge that has to
be treated, transported and distrib-
uted. The quality of sludge is another
important factor. If the sludge is the
product of a highly industrialized
area, it may contain undesirable
chemicals which will require more
advanced treatment and a greater
degree of monitoring at the applica-
tion site, meaning higher system costs.
Some sludges may actually be unsuit-
able for agricultural use due to
excessive levels of organic chemicals
or heavy metals.
Quantity and quality of
sludge are critical factors...
The costs also depend greatly upon
the distance sludge must be trans-
ported prior to application and the
type of equipment selected for
dispensing the sludge product. Truck
spreaders, movable big-gun sprinklers,
portable sludge pumps, tank trailers
and large "nurse" supply tanks are
possible components of a program's
equipment list. The choice of specific
equipment largely depends on local
soil characteristics, the relative size
of the overall program and the
preferred distribution method of
local farmers.
Personnel requirements again de-
pend on the equipment used and the
project scope, but generally include
a program manager, clerical assistants,
equipment operators, monitoring
personnel, laboratory technicians,
and an assortment of seasonal and
part-time employees for peak de-
mand periods.
Program Statistics
The BIOGRO and METROGRO pro-
grams provide some operating statis-
tics that may serve as basic guidelines
for other municipalities.
Salem's BIOGRO program produces
approximately 7,800 tons of stabilized
sludge per year. This is equivalent to
over 62 million gallons of liquid sludge
at a concentration of 3 percent dry
solids. A team of three tanker trucks
delivers the liquid sludge to farms for
use on about 2,000 acres of cropland.
In Madison, stabilized sludge pro-
duction averages only 5,480 tons per
year. This digested sludge is being
added to the storage lagoons, which
contain approximately 100,000 tons of
stabilized sludge produced prior to
the METROGRO program. A 10-year
program to remove the stored sludge
is planned, with 10,000 tons per year
to be distributed to some of the 10,000
acres of suitable farmland available
within 10 miles of the treatment plant.
As the program expands and the
lagoons are cleaned out, the city's
annual sludge disposal needs will fall
to about half the present level. What
this means for Madison is that, as the
program proceeds, operation costs,
equipment needs and personnel re-
quirements will actually decrease.
Differences and similarities in oper-
ating costs, system components,
monitoring efforts and sludge product
constituents for BIOGRO and METRO-
GRO are outlined in the accompany-
ing tables.
Comparison of Annual Costs for Agricultural
Application of Stabilized Sludge1
BIOGRO (Salem)
(Data for the year 1978)
METROGRO (Madison)
(Data for the year 1979)
Application Data
Volume —26,345,000 gallons
Solids content—2 6 percent
Dry weight —2,856 tons (dry basis)
Equipment Utilized2
4 tank trucks
2 field application vehicles
1 "big-gun" sprinkler
Cost of Program
Equipment "rental"
$ 72,400
Operation and maintenance $ 73,600
Total Annual Cost
Cost per ton of stabilized
sludge applied to agri-
cultural land
$146,000
$ 51 12
Application Data
Volume —7,554,000 gallons
Solids content —4 0 percent
Dry weight —1,260 tons (dry basis)
Equipment Utilized
4 tank trucks3
2 field application vehicles4
2 "nurse" tank trailers
1 lagoon dredge3
Cost of Program
Amortization of owned
equipment at 10%/yr
Equipment rental
Operation and maintenance
Total Annual Cost
Cost per ton of stabilized
sludge applied to agri-
cultural land
$ 14,000
$ 50,000
$ 56,000
$120,000
$ 95 245
'Reported costs are for transport and application of stabilized (digested) sludge Costs of sewage
treatment and sludge digestion are excluded
2Salem costs are based on equipment owned by the city but "rented" to the BIOCRO program
Rental cost reported is for 84 hr/month operation, additional operating time charged at $15 69/hr
for tank trucks and $15 71/hr for field application vehicles
'Madison leased 4 tank trucks and 1 lagoon dredge in 1979
"Owned equipment operated in 1979 —original cost = $142,000, 10%/yr = $14,000/yr
5Cost/ton reflects limited quantity of solids applied during 1979, in future years, economies of
scale will reduce the average cost/ton
-------
Comparison of Testing/Monitoring Programs for the BIOGRO (Salem) and METROGRO (Madison) Programs
Madison
Salem
Soil-plow layer
Madison
Salem
Soil-subsoil layer
Madison
Salem
Plant tissue
Madison
Salem
Groundwater
Madison
Salem
NOTES
— Daily frequency
= Monthly frequency
= Quarterly frequency
= Semiannual frequency
= Prior to application
'////,= Annually during
application
• = Third and fifth year
after application
Monitoring practices are
based on state guidelines
and regulations, research
programs at local univer-
sities, and minor differ-
ences in sludge quality
Also, at Madison, sludge
from lagoons has to he
sampled differently from
digester sludge
Characteristics of Salem and Madison Systems
Characteristic
Units
BIOCRO
(Salem)
METROCRO
(Madison)
Treatment Plant
Avg annual flow rate
Current avg annual raw sludge
Current avg annual stabilized sludge
Stabilization/Storage
Anaerobic digesters
Storage lagoons
Transport/Application
Highway tanker trucks
Field application vehicles
Field "nurse" tank trailers
Lagoon dredge
"Big-gun" sprinkler
Application acreage
Stabilized sludge application rate
million gal/day
tons/yr—dry matter
tons/yr^dry matter
cubic feet
cubic feet
number/capacity
number/capacity
number/capacity
number/capacity
number
acres
tons/acre/yr —dry matter
28
12,000 (est )
7,800 (est )
1,007,654
699,000
3 @ 6,000 gal, 1 fa) 2,500 gal
2 & 2,500 gal
none
none
1
2,000
2
35
9,490
5,480
390,000 (addn'l 420,000 under const ;
8,020,000
4 & 5,500 gal (addn'l 2 @ 5,500 gal ordered)
2 (q> 3,800 gal (addn'l 1 3,800 gal ordered)
2 (8 12,000 gal (addn'l 1 <8 12,000 gal ordered)
1 (?) 1,000 gal/minute ordered
none
600 in 1979 (addn'l acreage available)
2 1 (range 1 2 to 2 5)
NOTES 1 Madison has approximately 100,000 tons stabilized sludge stored in lagoons from years prior to institution of the METROGRO agricultural
program, hence, their equipment needs are dictated by stored sludge plus current production A 10-year program to remove stored stabilized
sludge is planned
2 Salem has insufficient equipment to utilize all current sludge production through their BIOCRO program
Typical Stabilized Sludge Product Analyses of Salem's BIOGRO and Madison's METROGRO
BIOGRO (Salem)
METROGRO (Madison)
Constituent
Concentration
(mg/kg)
Percent
of solids
by weight
Ib/acre added m a
2 dry ton/acre
application
Concentration
(mg/kg)
Percent
of solids
by weight
Ib/acre added m a
2 dry ton/acre
application
Humus 500,000
Primary Nutrients
Total nitrogen as N 99,000
Available nitrogen as N 18,750
Phosphorus as P 7,500
Potash as K 250
Secondary Nutrients
Calcium as Ca 18,750
Magnesium as Mg 12,500
Soluble Sulfate as S 2,000
Micronutnents
Boron (hotwater soluble) as B 25
Copper as Cu 300
Iron as Fe 22,500
Manganese as Mn 200
Molybdenum as Mo 15
Zinc as Zn 2,000
Other Metals
Cadmium as Cd 20
Lead as Pb 410
Mercury as Hg 1 5
Nickel as Ni 29
Chromium as Cr 38
Arsenic as As 01
5000
990
1 88
075
003
1 88
1 25
0 20
003
2 25
002
020
004
2,000
396
75
30
1 0
75
50
80
001
1 2
90
08
006
80
008
1 6
0006
0 12
0 15
00004
500,000
105,000
37,500
14,000
7,500
51,000
9,000
325
300
525
8,750
200
10
2,350
32
371
16
79
272
90
5000
10 50
3 75
1 40
0 75
5 10
090
003
003
005
0 88
002
0 24
004
001
003
2,000
420
150
56
30
204
36
1 3
1 2
2 1
35
08
004
94
0 13
1 5
006
0 32
1 1
004
-------
What's Ahead
All over the country, people who
have implemented properly managed
sludge reuse programs are enthusias-
tically talking about their successes...
and many municipalities listening to
these comments are pursuing similar
programs of their own. These people
who have been directly involved in
sludge reuse programs can attest to
the benefits that have been realized
by the agricultural community and
the municipality when good quality
sludge is recycled.
Some people, like Jim Cunningham,
who has been Organic Solids Reuse
Manager for Madison's METROCRO
program since it began, talk about the
effectiveness and economics of reuse.
"From our viewpoint;' he explained,
"the use of METROGRO is a really
successful way of recycling nutrients
back to soil. For our sludge and our
situation, it is by far the cheapest way
of sludge disposal!'
Others speak about the manage-
ment and flexibility of such programs.
"As the METROGRO program is imple-
mented, we see how well-conceived
the original plans are. The equipment
scheduling and management of the
program all stress the flexibility which
is necessary to accommodate the
needs of the landowners who are
interested in using Madison's sludge.
The program should serve as a model
for many municipalities!' So said
Gloria McCutcheon, Section Chief,
Municipal Wastewater, Bureau of
Water Quality, Wisconsin Department
of Natural Resources.
The farmers who use a municipal
sludge product also talk of its benefits.
Said Fred and Bob Uphoff, Madison
area farmers who grow corn on 124
acres, "During the past several years,
we have used METROGRO on our
land and find it has greatly improved
the texture and water holding capacity
of the soil. It is also a good source of
nitrogen. We feel fortunate that we
have had access to this good organic
fertilizer!'
BIOGRO has also had its share of
acclaim. People have called it "an
excellent supplement to commercial
fertilizer" (Gary Clark, Salem area
farmer). It has been labeled "an excel-
lent example of how wastewater
treatment sludges can be recycled
and put to a beneficial agricultural
use" (EPA Region X staff). And those
involved with BIOGRO have charac-
terized themselves as "a firm believer
in the program" (Larry McCaffrey,
Salem's wastewater treatment plant
superintendent).
But not every program will take the
shape of a BIOGRO or a METROGRO.
As similar programs develop in other
areas, they vary to meet the special
requirements of location, economy
and type.of agriculture. For instance,
in Conway, South Carolina, the Grand
Strand Water and Sewer Authority is
developing a sludge reuse system
involving owner-operated farming. By
late spring 1981, they expect to be dis-
posing of liquid digested sludge via
big-gun sprinklers on their 150-acre
site. The Bermuda grass grown there
will be sold as forage to the livestock
areas northeast of Conway.
So sludge is taking its place as a
resource. From coast to coast, munic-
ipalities are finding that recycling
sludge, whether on private or public
farmland, can provide a cost-effective
solution to the sludge disposal prob-
lem. On the other hand, farmers have
discovered the benefits of participat-
ing in sludge reuse programs—their
fertilizer costs decrease, their yields
increase, and their soil quality improves.
Of course, the application of sludge
to agricultural and other lands must
still be closely examined in terms of
protecting human health and future
land productivity. The results of con-
tinuing investigations of land applica-
tion and other sludge management
alternatives aimed at improving these
practices will be incorporated into
future changes in regulations and guid-
ance issued by the Federal and state
regulatory agencies. However, where
projects are carefully planned and
managed, those responsible for moni-
toring the quality of our land, air and
water resources have supported sludge
recycling to the land for agricultural
and other uses as acceptable means
for sludge management.
Recycling municipal sludge for ag-
ricultural use can help reduce the
wastewater treatment burden felt by
the cities. In addition, the farmers can
benefit by being able to use a for-
merly discarded, low-cost nutrient
source. Finally, in a world of diminish-
ing resources and increasing demands,
recycling is a solution that makes sense.
-------
EPA is charged by Congress to protect the Nation's land, air and water systems Under a mandate of national
environmental laws focused on air and water quality, solid waste management and the control of toxic substances,
pesticides, noise and radiation, the Agency strives to formulate and implement actions which lead to a compatible
balance between human activities and the ability of natural systems to support and nurture life
If you have questions or desire further informa-
tion on sludge recycling for agricultural use,
they may be directed to your nearest EPA
Regional public information office
EPA Region 1 • JFK
Federal Bldg. • Boston
MA 02203 • Connec-
ticut, Maine, Massachu-
setts, New Hampshire,
Rhode Island, Vermont •
617-22 )-7223
EPA Region 2 • 26
Federal Plaza • New
York NY 10007 • New
Jersey, New York, Puer-
to Rico, Virgin Islands •
212-264-2515
EPA Region 3 • 6th
and Walnut Streets •
Philadelphia PA 19106
• Delaware, Maryland,
Pennsylvania, Virginia,
Vest Virginia, District of
olumbia • 215-597-4081
PA Region 4 • 345
ourtland Street NE •
tlanta GA 30308 •
.labama, Georgia,
londa, Mississippi,
lorth Carolina, South
arohna, Tennessee,
entucky • 404-881-3004
PA Region 5 • 230 S.
learborn • Chicago IL
0604 • Illinois, Indiana,
)hio, Michigan, Wiscon-
m, Minnesota •
!12-i5)-2072
EPA Region 6 • 1201
Elm Street • Dallas TX
75270 • Arkansas, Loui-
siana, Oklahoma, Texas,
New Mexico •
214-767-2630
EPA Region 7 • 324
East 11th Street •
Kansas City MO
64106 • Iowa, Kansas,
Missouri, Nebraska •
816-374-6201
EPA Region 8 • 1860
Lincoln Street •
Denver CO 80295 • Col-
orado, Utah, Wyoming,
Montana, North Dakota,
South Dakota •
S03-837-S878
EPA Region 9 • 215
Fremont Street • San
Francisco CA 94105 •
Arizona, California, Hawa
Nevada, Pacific Islands
• 415-556-1840
EPA Region 10 • 1200
Sixth Avenue • Seattle
WA 98101 • Alaska,
Idaho, Oregon, Washing-
ton • 206-442-120)
repared by ChUMHHILL
nder Contract No WA-8-2305-B
ditor Barry Creenberg
esign Anne M Adams
David E Livingston
PA Project Officer Robert K Bastian
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