United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/062 Aug. 1985
&EB\ Project Summary
Demonstration of Acceptable
Systems for Land Disposal of
Sewage Sludge
A project was conducted to demon-
strate systems for managing sewage
sludge application to farm land and to
investigate sludge-related health risks
to rural residents and their livestock.
The study areas included four commu-
nities representative of Ohio condi-
tions-Columbus, Defiance, Springfield,
and Medina County.
The study demonstrated that large
municipalities can work cooperatively
with large numbers of farmers in a mu-
tually beneficial program. Health risks
were found to be insignificant when
sludge was applied at the low applica-
tion rates of this study using the man-
agement systems described here.
This Project Summary was devel-
oped by EPA's Water Engineering Re-
search Laboratory and Toxicology and
Microbiology Division, Health Effects
Research Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Sewage sludge has been disposed of
on farms throughout the United States
for many years, with only occasional
problems arising from careless han-
dling or mismanagement. However,
such incidents can be irritating and pos-
sibly hazardous to the farm community.
The need existed for demonstrations of
the best available sludge application
technology. The potential problems and
health risks associated with sludge ap-
plications to land are still real issues for
many Ohio farmers. Members of the
Ohio Farm Bureau Federation have re-
peatedly voted to sponsor or seek sup-
port for a project to demonstrate man-
agement systems that would address
the rural community's concerns and
that would more clearly define the
health risks to local residents and their
livestock. This project met those needs
by conducting 15 separate studies on
the topics of concern. The general areas
of study and the results are discussed
here briefly.
Management Systems
A major objective of this project was
to define and demonstrate sludge appli-
cation management systems that would
minimize adverse effects on the rural
community. The key factors in manag-
ing land application of sewage sludge
on privately owned farm land are de-
scribed as follows.
A. A large number of farmers and ap-
plication sites should be involved
so that the general public will not
identify a particular farm or neigh-
borhood as the sludge disposal
site.
B. Public meetings, consultation with
community leaders, field days,
etc., should be held to make the
public fully aware of the scope, ob-
jectives, and safety of the pro-
gram. The residents of Ohio were
generally supportive of the con-
cept of applying sludge to farm
land as long as there was a consid-
ered management approach that
minimized odor problems,
avoided nuisance situations in the
transport and handling of the
sludge, and maintained the metal
content of the sludge at reason-
able levels.
C. These projects should use low
sludge application rates that pro-
vide enough sludge for either the
nitrogen or phosphorus require-
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ments of crops. This concept is
readily accepted by the public.
Such rates provide for efficient
use of the plant nutrients in the
sludge, and they minimize the po-
tential for surface runoff and
groundwater pollution since the
level of nutrients applied are com-
parable with fertilizer applications
on non-sludge-treated land. Low
application rates also minimize
the possibility of damages result-
ing from the land application of
unwanted metals or organics in
sludge whose quality has not been
adequately monitored.
D. A rapport should be developed be-
tween those who spread the
sludge and the farmers who re-
ceive it. Someone versed in agron-
omy is needed to serve as liaison
between the farmers and the
sludge generator. This person
should discuss with the farmer the
nutrient value of the specific loads
of sludge to be received. The liai-
son should also present a contract
to farmers to define the working
relationship between the farmer
and the sludge generator. In gen-
eral, the job of the liaison is to
trouble-shoot and maintain a
good relationship between farm-
ers and sludge generators.
E. Sludge quality should be moni-
tored closely, and care should be
taken to produce a well stabilized,
odor-free sludge. Odorous
sludges do arise when sewage
plants are not functioning prop-
erly. The disposal of such sludges
on the land must not be consid-
ered an emergency that the public
must simply accept. A plan for
such situations should be worked
out ahead of time. At the very
least, odorous sludges should be
incorporated into the soil as they
are applied on the land.
When these recommendations were
followed carefully, a good relationship
was maintained between farmers and
cities of all sizes. Large volumes of
sludge were applied to the land at tow
application rates with very few com-
plaints from the public.
Problems were encountered when
the City of Columbus applied a very
odorous sludge to farms in Pickaway
County. This application was consid-
ered an emergency effort by Columbus
officials and was not conducted as part
of this project. Unfortunately, commu-
nications broke down between the pro-
ject staff and the city regarding this ap-
plication. The result was an injunction
by the Pickaway County Board of Health
against all land application of Columbus
sludge within Pickaway County. This ex-
perience indicates that application of
odorous sludges to the land requires
very careful planning. The only accept-
able approach is to incorporate the
sludge as it is applied to the land.
Health Risks
Another major objective of this pro-
ject was to evaluate health risks to rural
residents and their livestock resulting
from the application of sludge to crop
land. Studies were designed to deter-
mine whether the presence of sludge on
land in the rural community would in-
crease the risk of disease above that as-
sociated with daily living. Literature re-
views were also made of the risks
associated with sewage sludge.
Health risks were not significant when
sludge was applied using the low appli-
cation rates and management systems
of this study. The risks of respiratory ill-
ness, digestive illness, infection with
Salmonella, Shigella sp., and Campy-
lobacter sp., and general symptoms of
illness were not significantly different
between sludge and control groups.
Similarly, no significant differences oc-
curred in the health of domes'tic animals
on sludge and control farms. Viral infec-
tions among household members
showed no significant difference in fre-
quency between the sludge and control
groups. Fecal Cd levels in humans were
not significantly affected by the expo-
sure of rural residents to sewage
sludges.
Agronomic Studies
Agronomic studies were conducted
to support and evaluate the land appli-
cation program. Field plots were main-
tained to demonstrate that crop yield re-
sponse to sludge, metal accumulation
in soils, and metal accumulation in plant
tissue under Ohio conditions were typi-
cal of results reported in the literature.
This information was used in educa-
tional programs for the public and for
sanitary engineers, public health offi-
cials, and other interested profession-
als.
Monitoring Sludges for Metals
The metal contents of six sludges
were monitored for 3 to 4 years. Sludge
samples were collected daily, and anal-
ysis was performed on a monthly com-
posite. These analyses were considered
sufficient for monitoring the quantities
of metals that might be applied to soils.
Compositions were reasonably steady
throughout this period. Abrupt changes
were observed only when sewage plant
modifications were started up or when
industrial pretreatment programs were
initiated.
Soil Compaction from Applica-
tion Vehicles
Soil compaction studies were con-
ducted in the Medina project to evaluate
the possible damage to soil structure re-
sulting from the travel of application ve-
hicles through fields. This issue re-
quires further study, since we could
observe compaction effects with only
one type of application vehicle on one
soil type. Also, the application rates in
the Medina area were fairly low and re-
quired only one or two passes of the
application vehicle to provide the total
annual application. Soil compaction re-
sulting from the sludge application
equipment was not of great concern un-
der the conditions of the Medina pro-
ject.
Nitrogen Mineralization and
Ammonia Volatilization
A number of Ohio sludges were used
in laboratory studies of nitrogen miner-
alization and ammonia volatilization
losses from soils amended with sewage
sludge. Nitrogen mineralization of
sludge in soils was extremely variable,
depending on the sludge and field con-
ditions. Based on this research, a 30 per-
cent mineralization rate is recom-
mended for estimating nitrogen release
when sludge is first applied to the land.
The study examined a number of pa-
rameters that influence the volatiliza-
tion of ammonia from sludge-amended
soils. The most important observation
was that ammonia is quickly lost when
sludges are applied to soil surfaces. In
this project, sludges were applied to the
surface of soils and often remained on
the surface for a week to 2 months be-
fore incorporation into the soil. Most of
the nitrogen was assumed to have been
lost. Such losses cannot be avoided
when applications are made to hay and
pasture lands and to fields that support
application equipment but are not in a
suitable condition for tillage at the time.
PCB Degradation and Absorp-
tion
A laboratory study was conducted on
the factors affecting soil degradation
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md plant absorption of PCB from PCB-
dmended sewage sludge. The sludges
used in the field demonstrations were
not contaminated with PCB, but con-
cern always exists about the possibility
of PCB soil contamination resulting
from application of sewage sludge. PCB
resisted biodegradation in soils.
Volatilization from soils was decreased
by their organic component. Uptake of
PCB by Kentucky 31 fescue was very
limited. Possible contamination of crop
land with PCB and other toxic organics
is a concern to farmers who receive
sludge. More research is needed on the
hazards associated with the presence of
these materials in the soil. Also needed
are less expensive and more reliable
methods for monitoring the presence of
toxic organics in sludge.
Status of Sludge Application in
Ohio
A survey was made of the state of the
art of sludge application to land in Ohio.
A total of 56 landspreading communi-
ties were identified in this state. The
quality of landspreading programs in
Ohio has been improved substantially
over the past 5 years. Communities are
more aware of the contents of their
sludges, and they spread them more ju-
diciously.
Computerized Economic Analy-
sis
An economic analysis of sludge
spreading on land was prepared in a
computer format so that the specific
conditions of a given community could
be quickly evaluated. Land spreading of
a sludge is an economic method of dis-
posal for most Ohio communities.
Extractability of Cadmium
The effect of soil pH on the ex-
tractability of Cd was observed for sev-
eral Ohio soils and sludges in laboratory
studies. The movement of Cd from
sludge-treated soils into the food chain
is a concern. The extractability of Cd in
sludge-amended soils increased dra-
matically as the pH of the system
dropped below 6.0.
The full report was submitted in fulfill-
ment of Cooperative Agreement No. CS
805189 by the Ohio Farm Bureau Devel-
opment Corporation underthe sponsor-
ship of the Water Engineering Research
Laboratory and the Health Effects Re-
search Laboratory's Toxicology and Mi-
crobiology Division of the U.S. Environ-
lental Protection Agency.
Robert Bro wn is with the Ohio Farm Bureau Development Corporation. Columbus.
OH 45216; Terry Logan, Richard Dorn, Vincent Hamparian, and Abramo C.
Ottolenghi are with the Ohio State University, Columbus. OH 43210.
G. K. Dotson is the EPA Project Officer (see below).
The complete report, entitled "Demonstration of Acceptable Systems for Land
Disposal of Sewage Sludge," (Order No. PB 85-208 874/AS; Cost: $37.00.
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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EPA/600/S2-85/062
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