Recycling
Municipal Sludges
and
Effluents on Land
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Proceedings
of the Joint
Conference on
Recycling
Municipal Sludges
~_ -"- K A ^ x-~-x^-s. ^^"^
and
Effluents on Land
July 9-13, 1973
Champaign, Illinois
Sponsored by:
The Environmental Protection Agency
The United States Department of Agriculture
The National Association of State Universities
and Land-Grant Colleges
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Printed in the United States of America
Library of Congress Catalog No. 73-88570
National Association of State Universities and Land-Grant Colleges
One Dupont Circle, N. W,
Washington, D. C. 20036
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CONTENTS
Foreword vii
Subcommittee on Recycling Municipal Sludges and Effluents on Land ix
Federal and State Legislative History and Provisions for Land Treatment of
Municipal Wastewater Effluents and Sludges 1
Ralph H. Sullivan, Esq., Environmental Protection Agency
Land Application of Wastewater With a Demographic Evaluation 9
Belford L. Seabrook, Environmental Protection Agency
Some Experiences In Land Acquisition for a Land Disposal System for
Sewage Effluent 25
John C. Postlewait, Muskegon County Department of Public Works
and Harry J. Knudsen, Muskegon County Corporate Counsel
The Properties of Sludges 39
K. fi. Dean and ./. E. Smith, Jr., Environmental Protection Agency
Characteristics of Municipal Effluents 49
Charles £. Pound and Ronald W. Crites, Metcalf & Eddy, Inc.
\ Regional View On the Use of Land for Disposal of Municipal Sewage and Sludge 63
R. J. Schneider, Environmental Protection Agency — Region V
The Physical Processes In the Soil as Related to Sewage Sludge Application 67
Eliot Epstein, United States Department of Agriculture
Physical Changes to Soils Used for Land Application of Municipal Waste —
What Do We Know? What Do We Need to Know? 75
A. E. Erickson, Michigan State University
iii
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Soil Microbiological Aspects of Recycling Sewage Sludges and Waste Effluents
On Land 79
Robert H. Miller, Ohio State University and Ohio Agricultural R&D Center
Inorganic Reactions of Sewage Wastes With Soils 91
W. L. Lindsay, Colorado State University
Organic* 97
F. E. Broadbent, University of California
Land Treatment of Liquid Waste: The Hydologic System* 103
Herman Bouwer, United States Department of Agriculture
Land Resources 113
K. W. Flach, Soil Conservation Service
Soil-Plant Relationships (Some Practical Considerations In Waste Management) 121
S. W. Melsted, University of Illinois
Crop and Food Chain Effects of Toxic Elements in Sludges and Effluents 129
Rufus L. Chaney, United States Department of Agriculture
Crop Selection and Management Alternatives — Perennials 143
William E. Sopper, Penn State University
Recycling Urban Effluents On Land Using Annual Crops 155
A. D. Day, University of Arizona
Engineering and Economics of Sludge Handling 161
W.J. Bauer, Bauer Engineering, Inc.
Recycling Municipal Sludges and Effluents On Land 169
T. C. Williams, Williams and Works
Economic Aspects of the Application of Municipal Wastes to Agricultural Land 175
W. D. Seitz and E. R. Swanson, University of Illinois
Monitoring Considerations for Municipal Wastewater Effluent and
Sludge Application to the Land 183
Paul A. Blakeslee, Michigan Department of Natural Resources
Institutional Options for Recycling Urban Sludges and Effluents On Land 199
Robert R. Barbolini. Metropolitan Sanitary District of Greater Chicago
Public Acceptance — Educational and Informational Needs 207
John O. Dunhar, Purdue Univcrsitv
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CONTENTS
Some Extension Service Capabilities 213
Charles P. Ellington, University of Chicago
Informal Opinions on FDA's Outlook 215
Charles Jelinek, United States Department of Health, Education and Welfare
Workshop Session Reports 219
Participants 239
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Foreword
Municipal wastewater treatment is one of the Nation's major environmental prob-
lems. Treatment and disposal of billions of gallons of municipal wastewater
produced each day (approximately 71/2 billion gallons in 1972) involves two
primary difficulties: (1) environmentally acceptable and economical processing and
utilization of sludges generated during treatment, and (2) environmentally ac-
ceptable and economical removal of polluting materials from the liquid effluents.
Discharge of municipal wastewater has resulted in water pollution and air pollution.
The impact of water and air quality standards, the tremendous quantities of sludges
produced, and the expenditure of physical and monetary resources for conventional
methods of wastewater treatment have prompted a search for alternative methods.
One such alternative method, which utilizes our land resources, is known as Soils
Treatment Systems (STS). While not a new technology, its prior use has lacked the
in-depth evaluations required to assure that STS's are truly environmentally
acceptable.
As a consequence of this renewed interest in STS's, the leaders from the Environ-
mental Protection Agency, U. S. Department of Agriculture, and the National Land
Grant Universities created a Coordinating Committee on Environmental Quality,
recognizing that the utilization of land resources as treatment media required a coor-
dinated attack by multi-disciplinary interests. A subcommittee entitled "Recycling
Municipal Effluents and Sludges on Land" was created with the objective of
developing and implementing institutional procedures to effectively use the resour-
ces available within the EPA-USDA-University structures for a cooperative and
coordinated research, development, and demonstration program.
The initial task for this ad-hoc subcommittee was to identify what is known about
liquid effluent and sludge application to the land, and what research is needed for
successful utilization of land as a soils treatment system from economic, engineering,
health, and esthetic points of view. It was felt that the Nation's experts on STS should
be contacted to accomplish the above task.
Vll
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viii RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
This document presents information gathered at the Research Needs Workshop,
sponsored by the ad-hoc subcommittee on July 9-13, 1973, in Champaign, Illinois. It
will provide a firm foundation from which the ad-hoc subcommittee can work to
achieve its objective.
Darwin R. Wright, Chairman
Environmental Protection Agency
Office of Research and Development
Robert Kleis
Land Grant Universities
Agricultural Experiment Station
Carl Carlson
U. S. Department of Agriculture
Agricultural Research Service
(replaced J. S. Robins II \l 73)
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Subcommittee on Recycling Municipal
Sludges and Effluents on Land
EPA
G. K. Dotson Richard Thomas
Charles E. Myers John R. Trax
Belford L. Seabrook Darwin R. Wright, Chairman
USDA
William Crosswhite J. D. Menzies
J. O. Evans 7. S. Robins, Executive Committee
Richard Ford Paul Schleusner
Lawrence L. Heffner C. W. Carlson
UNIVERSITIES
J. E. Halpin S. W. Melsted
R. W. Kleis, Executive Committee Parker Pratt
W. E. Sopper
IX
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Federal and State
Legislative History
and Provisions
for Land Treatment
of Municipal
Wastewater Effluents
and Sludges
RALPH H. SULLIVAN, ESQ. *
Environmental Protection Agency
INTRODUCTION
Federal and State legislation and regulations that
relate directly to recycling municipal wastewater ef-
fluents and sludges on land is of fairly recent origin.
The Federal government has traditionally left the
jurisdiction of this activity in the province of State
and local governments, as essentially a public health
matter. However, the large amount of Federal grant
funds that have been made available, concern about
the total environment, and Federal laws and regula-
tions on land, water, and air quality have combined
to make the Federal government active in financing
and evaluating effective land treatment of municipal
effluents and sludges.
State and local governmental units have also
shown increasing interest in land treatment of efflu-
ents and sludges, both as a desirable method of waste-
water treatment under appropriate conditions and as
a public health matter which needs guidance and
regulation.
It is the aim of this paper to describe the develop-
ment and present status of the Federal legislation and
regulations framework under which land treatment
has become of concern to the Federal government
and has engendered financial support through Feder-
al grant programs. Also, State and local government
laws and regulations are discussed, although there
does not appear to be as much information readily
available in this area as would be practically useful.
* Program Counsellor, Municipal Waste Water Systems Division,
Office of Water Program Operations, Environmental Protection
Agency, Washington, D.C. 20460. The opinions expressed herein are
the author's and not necessarily those of the Environmental Protec-
tion Agency
Early Origins of Federal Concern with Water
Pollution Control
The precursor of all Federal legislation for water
pollution control was the Rivers and Harbors Act of
1899, which in Section 13 of the Act prohibited the
discharge or deposit of any refuse into navigable wa-
ters. This section, known as the "Refuse Act", re-
quired permits for any discharge of any refuse matter
of any kind or description into any navigable waters
of the United States so that navigation would not be
impeded. The meaning of the term "refuse" was de-
fined by a U.S. Supreme Court ruling in 1966. In
United States versus Standard Oil (384 U.S. 224, 230)
refuse was defined so as to include industrial pollu-
tants and to cover all foreign substances and pollut-
ants except for municipal sewerage. Very little en-
forcement of the provisions of the Refuse Act took
place until the early 1970's when concerned individu-
als and organizations filed so-called qui tarn actions,
which are citizen suits to stop violators of the no-dis-
charge provisions. Also stimulated by citizen con-
cern, over 20,000 permits for industrial discharges
were processed by the Corps of Engineers. These per-
mits have now been incorporated into permit activi-
ties of the Environmental Protection Agency under
the Federal Water Pollution Control Act Amend-
ments of 1972.
Between 1899 and 1948 there was little Federal
legislation pertaining directly to water pollution
abatement. Exceptions were: (1) the Public Health
Service Act of 1912 which provided for surveys and
studies of the effect of water pollution on human life,
but included no enforcement activities, and (2) the
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RECYCLING MUNICIPAL SI.IH)C-KS AND KKKl.rKNTS
Oil Pollution Act of 1924 which prohibited the dis-
charge of oil into coastal waters, but which was not
vigorously enforced.
Intermediate Legislation
In 1948, the Water Pollution Control Act was en-
acted. This was the first legislation that encompassed
broad areas of water pollution abatement, including
support for research and development and technical
assistance to the States. This statute also established
the policy that the States were to have the primary
role in abating pollution, with the Federal govern-
ment providing assistance and support. To this day,
the States are first given the opportunity to under-
take necessary pollution abatement measures on
their own, with the Federal government occupying a
back-up position. For example, the current permit
program under the Federal Water Pollution Control
Amendments of 1972 is designed to encourage the
States to establish their own permit programs rather
than have the program operated by the Federal gov-
ernment.
Overall, the 1948 legislation can be characterized
as premised on the basis that pollution abatement was
largely of local interest and not of national program-
matic concern. This view was held and affected poli-
cies until the passage of the FWPCA of 1956.
Modern Legislation
Federal Water Pollution Control Act of 1956
The Federal Water Pollution Control Act of 1956
was the first legislation that authorized Federal
grants on a large scale to assist States and municipali-
ties in planning and building facilities for treatment
of wastewaters. Under the provisions of this legisla-
tion, approximately five billion dollars was appropri-
ated and obligated from 1957 to 1972. Table 1 pro-
vides the exact data on the financing. Also included
are data on how each State utilized two billion dol-
lars in Federal funds for FY 1972.
The FWPCA of 1956 provided for a series of co-
ordinated actions to prevent and reduce water pollu-
tion. The action most pertinent to land treatment was
the fact that funds for research and development were
greatly increased. This provision later made it pos-
sible to begin the financing of the Muskegon land
treatment project.
However, the Act and regulations also contained
prohibitions and omissions that were not encouraging
TABLE 1
Municipal Wastewater Treatment Works
Construction Grants
Annual Authorizations, Appropriations,
Obligations & Expenditures
Fiscal
year
1957
1958
1959
I960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Total
Authorized
appropriation
i 50,000,000
50,000,000
50,000.000
50,000.(XX)
5(),(XX),(XX)
8(),(XX),(XX)
90,000,000
100,000,000
100,000,000
150,000,000
150,000,000
450,000,000
700,000,000
1,000.000,000
1,250,000,000
2.000,000.000
Actual
appropriation
$ 50,000,000
45,657,0001-
46,8l6,(XX)t
46,IOI,(XX)t
45,645,260 1
80,(XX),(XX)
90,(XX),(XX)
90,(XX),000
90,(XX),000
121,000,000
150,000,000
203,000,000
214,000,000
800,000,000
1,000.000,000
2,000,000,000
Fiscal year
obligations
$ 50,000,000
45,657,000
46,816,(XX)
46, 101, (XX)
45,645,260
8(),
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LEGISLATIVE HISTORY AND PROVISIONS
TABLE 1: (Continued)
Municipal Wastewater Treatment
Works Construction Grants
Summary of Utilization of Fiscal
Year 1972 Appropriated Funds as
of December 31, 1972
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
1 ouisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Guam
Puerto Rico
Virgin Islands
$ 33,785,150
3,548,
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to finding innovative means of disposal has been Sec-
tion 301 of the 1972 Amendments. This section re-
quires that all publicly-owned treatment plants proc-
ess their wastewaters so that effluent limitations based
on secondary treatment are achieved by 1977 (or
1978 for certain projects which arc under construc-
tion). This secondary treatment requirement will re-
sult in large increases in the amount of sewage sludge,
since under the definition of secondary treatment, all
floatable solids and, in general, 85 percent of suspen-
ded solids will have to be removed from municipal
wastewater effluents.
These three influences (the CEQ report, permits
for ocean disposal of sludge, and the secondary treat-
ment requirements) will add to the amounts of sewage
sludge to be disposed of and increase the urgency of
finding new ways to handle the vast quantities of
sludge.
Federal Water Pollution Control Act Amend-
ments of 1972
The Federal Water Pollution Control Act Amend-
ments of 1972 were enacted on October 18, 1972.
This Act has been characterized as the most compre-
hensive, and at the same time, the most complex, leg-
islation that has ever been enacted to clean up the
Nation's waters. A sweeping Federal-State-local gov-
ernment campaign is mandated, aimed toward pre-
venting, reducing, and eliminating water pollution.
Title II of the Act authorizes a multi-billion dollar
program to assist communities with 75 percent Feder-
ally funded grants for constructing sewage treatment
facilities. Such facilities include sewage treatment
plants, land treatment, interceptor sewers, sewage
collection systems, and separation of combined and
sanitary sewers. The particular configurations and
processes of any assisted sewerage project must be
chosen on the basis of the most cost effective method
over the life of the works.
It would be possible here to discuss all the details
of the legislation that could affect the applications of
land treatment, but it will suffice to discuss the provi-
sions that are most directly concerned with land
treatment. There are two sections, Sections 201 and
212. that need special attention.
Section 201 (d), (e), and (f). Subsections 201 (d),
(e). and (f) of the legislation were proposed by Con-
gressman Vander Jagt of Michigan on March 29,
1972, in order to insure that recycling and reclama-
tion of wastewaters would be eligible. The final Act
contains the exact text as proposed by the Congress.
Sections 201 (d), (e), and (f) read as follows:
"(d) The Administrator shall encourage
waste treatment management which results
in the construction of revenue producing
facilities providing for—
(1) the recycling of potential sewage pol-
lutants through the production of agricul-
ture, silvisulture, or aquaculture products,
or any combination thereof;
(2) the confined and contained disposal of
pollutants not recycled;
(3) the reclamation of wastewater; and
(4) the ultimate disposal of sludge in a
manner that will not result in environment-
al hazards.
"(e) The Administrator shall encourage
waste treatment management which results
in integrating facilities for sewage treatment
and recycling with facilities to treat, dispose
of, or utilize other industrial and municipal
wastes, including but not limited to solid
waste and waste heat and thermal dis-
charges. Such integrated facilities shall be
designed and operated to produce revenues
in excess of capital and operation and main-
tenance costs and such revenues shall be
used by the designated regional manage-
ment agency to aid in financing other envi-
ronmental improvement programs.
"(f) The Administrator shall encourage
waste treatment management which com-
bines 'open space' and recreational con-
siderations with such management.
In introducing this provision (as recorded in the
Congressional Record of March 29, 1972, p.H2740-
41), Congressman Vander Jagt made a fervent appeal
in these words:
"The concept of clean water for America is
a new concept, and we need to encourage
our people all we can to look at anything
that is new and promising.
James Russell Lowell told us years ago
that:
New occasions teach new ideas; we
Cannot make their creed our
jailer.
They must forever onward sweep,
and upward.
Who would keep abreast of truth.
Nor attempt a future's portal with
A past's outdated key.
Today we stand before the future's portal of
a new America. To open that door we
should not automatically pass one of na-
ture's own keys. Can we not choose the key
of tomorrow? It it does not fit then, nothing
is lost, but, if it does fit then for heaven's
sake let us open the door and walk into the
future of clean water for America."
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LEGISLATIVE HISTORY AND PROVISIONS
Congressman Vander Jagt's amendment was voted to
be included in the legislation by the margin of 250 to
130. Therefore, recycling and reclamation of waste-
waters have been given particular attention in the
bill.
Section 201 also contains under its Subsection
(g)(2) provisions that require consideration of appro-
priate alternate waste management techniques. They
read as follows:
"(gX2) The Administrator shall not make
grants from funds authorized for any fiscal
year begining after June 30, 1974, to any
State, municipality, or intermunicipal or in-
terstate agency for the erection, building,
acquisition, alteration, remodeling, im-
provement, or extension of treatment works
unless the grant applicant has satisfactorily
demonstrated to the Administrator that—
(A) Alternative waste management tech-
niques have been studied and evaluated and
the works proposed for grant assistance will
provide for the application of the best prac-
ticable waste treatment technology over the
life of the works consistent with the pur-
poses of this title; and
(B) as appropriate, the works proposed
for grant assistance will take into account
and allow to the extent practicable the ap-
plication of technology at a later date
which will provide for the reclaiming or re-
cycling of water or otherwise eliminate the
discharge of pollutants."
In commenting on this subsection, House Report No.
92-911 on the 1972 Amendments comments on pages
87-88, as follows:
"The Committee believes that applicants
must in the future be required to examine a
much broader range of alternatives for the
treatment of pollutants than they have here-
tofore typically done. It expects the Ad-
ministrator to provide leadership and to
stimulate research to assure the develop-
ment and application of new treatment
techniques. In arriving at the best practic-
able waste treatment technology considera-
tion must be given to its full environmental
impact on water, land, and air and not sim-
ply to the impact on water quality. There
may be no net gain to the Nation if we adopt
a technology to improve water quality with-
out recognizing its possible adverse effect
on our land and air resources.
The term 'best practicable waste treatment
technology' covers a range of possible tech-
nologies. There are essentially three cate-
gories of alternatives available in selection
of wastewater treatment and disposal tech-
niques. These are (1) treatment and dis-
charge to receiving waters. (2) treatment
and reuse, and (3) spray-irrigation or other
land disposal methods. No single treatment
or disposal technique can be considered to
be a panacea for all situations and selection
of the best alternative can only be made af-
ter careful study.
Particular attention should be given to
treatment and disposal techniques which re-
cycle organic matter and nutrients within
the ecological cycle.
In defining 'best practicable waste treat-
ment technology' for a given case, con-
sideration must be given to new or im-
proved treatment techniques which have
been developed and are now considered to
be ready for full-scale application. These
include land disposal, use of pure oxygen in
the activated sludge process, physical-
chemical treatment as a replacement for
biological treatment, phosphorus and nitro-
gen removal, in collection line treatment,
and activated carbon absorption for re-
moval of organics. Planners must also give
consideration, however, to future use of new
techniques that are now being developed
and plan facilities to adapt to new tech-
niques."
A caution should be added here, however, that
consideration apparently should be given to land dis-
posal techniques only where it is appropriate to do
so, since in the Conference Committee the language
of 201 (b) of the Act was changed to read that waste
treatment management plans and practices are re-
quired to consider advanced waste treatment tech-
niques, rather than "advance waste treatment tech-
nology and aerated treatment spray-irrigation tech-
nology." Therefore, land treatment must compete
with other possible treatment systems on a cost/ bene-
fit basis. Also, Section 212(2)(c) of the Act requires
that any grant application "contain adequate data
and analysis demonstrating such proposal to be over
the life of the works, the most cost efficient alter-
native."
Section 212. Section 212 of the Act, which covers
definitions, specifically authorizes site acquisitions of
the land that will be an integral part of the treatment
process or is used for ultimate disposal of residues re-
sulting from such treatment. This provision will al-
low the land that is used in the actual treatment, such
as the land that is used as a filter in the Muskegon
project, to be an eligible cost in a grant. However, the
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()
KKCYCUNC MUNICIPAL SLUDCKS AM) KKKLl'KNTS
land that is not so used, such as the real estate upon
which a conventional secondary treatment plant is
located, will continue to be a non-allowable cost.
The foregoing comments on the Federal legislation
of 1972 are meant to be illustrative of the present sta-
tus and trends in the legislative history. The com-
ments are subject to revisions as new interpretations
and legal rulings on the law are made.
EPA Grants for Sewage Treatment Projects
It will be useful here to list the major require-
ments for EPA grants for sewage treatment projects:
• All projects must have a priority certification
from the State and conform to planning require-
ments.
• All projects must be analy/.cci for cost effective-
ness.
• Pretreatment of industrial wastes is necessary.
• Hnvironment assessment is necessary.
• Secondary treatment is required, with best prac-
ticable control technology applicable for grants
financed with FY 1976 funds or later.
• All projects must also meet planning require-
ments to be processed through the State Agency.
The requirements for grant processing are con-
tained in EPA's so-called Title II Regulations which
were published in interim form on February 28, 1973,
with Federal Regulations to be published in fina,l
form in the Fall of 1973.
An innovation in the regulations is the introduc-
tion of a three-step method of making grants. Step I
allows a separate grant for the preparation of con-
struction drawings and specifications; Stc/> 2 provides
for a grant for the preparation of construction draw-
ings and specifications; and Step .? is for a grant for
the building and erection of the treatment works. This
division of the financing of a grant for a project will
accelerate payments to the communities and allow
available funds to be spread over a larger number of
projects so that pollution abatement may be acceler-
ated.
Having completed a broad review of Federal legis-
lation, it is appropriate next to consider State legisla-
tion.
State Laws and Regulations
State laws and regulations on land treatment are
in an early state of development. Surveys of state leg-
islation have been completed by Temple University
and the American Public Works Association.
A. The Temple University study, Green Land:
Clean Streams (Center for Study of Federalism at
Temple University. Philadelphia, Pennsylvania 1972),
contains a very detailed evaluation of its survey re-
sults on State laws pertaining to land treatment. The
survey found that 14 States had legislative enactments
that were either favorable or unfavorable to land
treatment.
The survey also sought to evaluate the attitude of
States toward land treatment. Fourteen States were
found to be favorably oriented toward implementa
tion of land treatment, three were neutral, and the
rest were impossible to judge as to attitude on the
basis of available data. Table 2 is a rendition of a
chart in the works which tabulates the attitudes of the
States.
B. The American Public Works Association Re-
search Foundation study, entitled Survey of l-a< ilities
Ufiinx Land Applications <>l Wuslewiter (C'hicago,
1973) contains a section on its survey ol opinions arid
regulations ol State health and water pollution con-
trol agencies on the application of wastewaters on
land areas.
The survey led to the conclusion that more atten-
tion needs to be given by States to the regulations of
land treatment projects. The study expresses it in
these terms:
"If the alternative method of managing
wastewater effluents by application on land
areas is to become more universally utilized
by municipalities and industries it must re-
ceive more specific consideration by state
health and natural resources authorities
than it is now given. The fact that the one
thousand and more land application sites
now in service in the United States have re-
ceived minimal regulatory control in the
past emphasizes the need for a greater rec-
ognition of the problem and a consequent
increase in regulatory control in the fu-
ture."
CONCLUSION
Both Federal and State legislation and regulations
related to land treatment are in a state of develop-
ment. This paper reflects the current situation and the
range of actions possible under present rules. The re-
sults of research and development, demonstration
projects, and working installations will help to deter-
mine future legislation and regulations
DISCUSSION
QUESTION' A. Kaplovsky, Rutgers University.
Mr. Sullivan was talking about some of the legislative
points that would create some future problems for
us that we have to consider. One point that I feel was
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LEGISLATIVE HISTORY AND PROVISIONS
TABLE 2
Disposition of the States Toward Implementation
of Land Treatment Facilities
f-a»mihU' Orientation
Arizona*
California
Colorado
Idaho
Maryland
Montana
New Jersey
New Mexico
New York
North Dakota
Oklahoma
Texas
Vermont
Wisconsin
Judgement Not
Neutral Negative (Mentation on Data Available
Alabama Arkansas Connecticut
Alaska Florida Delaware
Massachusetts Illinois Georgia
Iowa1 * Indiana
Kansas* * Hawaii
Maine* * Kentucky
Michigan* * Louisiana
Nebraska Minnesota
Utah Mississippi
Virginia Missouri
Washington Nevada
New Hampshire
North Crolina
Ohio
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
West Virginia
Wyoming
1 listed alphabetically, not ranked
* * permits land treatment but with restrictions
left out, which I think would be a great concern to
most of us, is the fact that the new legislation en-
courages area-wide regionalization of treatment
facilities. If you think a moment how this can affect
areas, particularly as it is being looked at in New Jer-
sey, we have to consider that these would include es-
sentially all industry, and that all industrial waste, by
a large measure, would be going into regional sys-
tems, particularly whether resisting industries from
discharging directly to streams, even though their de-
gree of treatment is essentially the same as the public
facility that is being planned.
My question, is EPA considering this as "an addi-
tional source of sludge" that they have to contend
with?
ANSWER: You will find that this cost effective-
ness is going to be the answer to your question. If it is
more cost effective to go to regionalization, that will
probably be the predominant influence. But, I can see
many instances, including New Jersey, where it won't
be least expensive to go to one large system, and as
was mentioned in the Muskegon Project that there
could be some tendency with land treatment, whether
the necessary factors are present, to break down the
system and have several systems instead of one large
system.
I don't think that Section 208 of the Act does call
for waste management agencies. Section 208 regula-
tions will be issued very shortly. I think you will find
that they are very flexible, but if they aren't flexible,
please write in so that we can have the benefit of your
thoughts and change them before we issue them
finally.
QUESTION: William Bauer, Bauer Engineers,
Chicago, Illinois. The recent law provides that the
land which is used for treatment is eligible for grants,
and I was wondering what is the current thinking of
the EPA on the matter of funding for land acquisi-
tion? On the case of the Muskegon Project the cost of
the land was a hundred percent local, but I under-
stand that is going to be changed.
ANSWER: The legislation states that the land that
is directly used in the waste treatment is eligible as a
cost. The land in a Muskegon type project would be
eligible provided the state certifies the project.
-------
Land Application
of Wastewater
With a
Demographic
Evaluation
BELFORD L. SEABROOK
Environmental Protection Agency
INTRODUCTION
The American Public Works Association Re-
search Foundation, in 1972, conducted an on-site
field survey of approximately 100 facilities in all cli-
matic zones where community or industrial waste-
waters are being aiplied to the land, as contrasted to
the conventional method of treating such wastes and
discharging them into receivinl waters.
Additional data were gathered from many existing
land application facilities across the country by
means of a mail survey addressed to responsible offi-
cials. Another survey was carried out to ascertain the
nature and extent of State health and water pollution
control regulations governing the use and control of
land application systems. To augment information on
U.S. practices, a survey was made of experiences
gained in certain foreign countries. In addition, an
extensive bibliography was compiled of literature on
all pertinent phases of land application practices.
The facilities surveyed were relatively large long-
established operations. These were selected to obtain
as much information as possible on the operating ex-
perience of those using this technique. The surveyed
facilities whose municipal wastes were applied on
land were predominately located in western and
southwestern portions of the U.S., while industrial
facilities were generally sited in the northeastern sec-
tion, because this is where the majority of such instal-
lations are in service. This method of handling waste-
water has been used to meet definable needs and is
technically feasible in most areas.
Land application of effluent has been employed for
a variety of reasons. Those most frequently men-
tioned were:
1. To provide supplemental irrigation water.
2. To give economical alternative solutions for
treating wastes and discharging them into receiv-
ing waters, without causing degradation of
rivers, lakes and coastal waters.
3.To overcome the lack of suitable receiving waters
and eliminate excessive costs of long outfall lines
to reach suitable points of disposal into large
surface bodies of water.
Among the major means of accomplishing land ap-
plication of wastewaters are:
1. Irrigation of land areas by spraying, with high-
pressure or low-pressure devices, using either
stationary or moveable types of distribution sys-
tems.
3. Ridge and furrow irrigation systems.
4. Use of infiltration lagoon or evaporation ponds.
Although facilities of all types were surveyed, this
report is primarily concerned with irrigation-type
facilities for supplying supplemental water to crop
areas, forest areas and unharvested soil cover acre-
ages. The other types are not as widely used, because
the climate or soil conditions in some locations have
an adverse impact on these alternative methods of ap-
plying wastewater to land.
Irrigation-type facilities were found to be used in
many instances under a wide variety of climate and
soil conditions, with various degrees of prior treat-
ment of the applied wastewater and various types of
-------
10
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
ground cover utilized.
Each method of application has inherent advan-
tages and disadvantages which must be evaluated for
their feasibility and efficacy.
Land application of wastewaters has been prac-
ticed extensively in various parts of the world for
many years, long before the turn of the century. The
majority of earlier facilities applied untreated
domestic wastewaters with varying degrees of control
and success.
As knowledge of wastewater treatment processes
improved, and techniques were developed, confining,
in a relatively small area, the entire process needed to
produce a "treated" effluent for disposal into receiv-
ing waters, land application was relegated, in most
states, to being an undesirable and unacceptable
process.
New concerns about preserving the quality and re-
use of the nation's water resources have resulted in a
reawakening of interest in land application as a vi-
able alternative to conventional wastewater treat-
ment and disposal into receiving waters. Increasing
volumes of sewage and industrial wastes, growing
complexity of such raw wastes, and mounting needs
for water to serve growing urban and industrial proc-
essing needs, have created doubts about the ability of
receiving waters to assimilate effluents which do not
meet high-quality standards. In addition, increasing
evidence of eutrophication of non-flowing receiving
waters has focused attention on the need to eliminate
the presence of nutrients in wastewater effluents. Fur-
ther, the presence of toxic trace elements in effluents
is sometimes considered a threat to the safety of re-
ceiving waters. Thus, advanced treatment methods
have been developed and utilized to avoid discharge
of such objectionable components. Inasmuch as land
application appears to offer comparable or superior
degrees of treatment by augmenting waste treatment
with the "natural" purification offered by soil con-
tact, land application is again being considered as
one of the acceptable means of achieving full treat-
ment of wastewaters.
However, a most important factor of the current
land application concept is that it be limited to the
use of treated wastes. Generally, effluents are being
conventionally treated to meet secondary treatment
quality criteria. In at least three observed facilities,
applied effluents have received tertiary treatment, to
the point where the effluent would fully meet the gen-
erally prescribed, as well as proposed, criteria for
discharge to receiving waters. Thus, land application
is being used to give a degree of advanced waste
treatment, including high degrees of nutrient and
bacterial removal. In this context, land application
can be viewed as an alternative to physical-chemical
processes and other methods of ultra-treatment which
are designed to achieve a high quality effluent.
Economics of construction cost, operating costs,
energy requirements, and efficiencies of performance
of land application systems must be balanced with (In-
ability to acquire the right to apply w.isicwater upon
the required land areas. The cost of advanced waste
treatment by conventional means must be weighed in
the light of the cost and complexities of land appli-
cation systems.
Two informative reports were published on the
subject of land application in 1972. Green Lands -
Clean Streams, a report by Temple University Cen-
ter for the Study of Federalism, is a frankly written
advocacy of the land application of wastewaters and
sludges. Wastewater Management by Disposal on the
IMH
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LAND APPLICATION
11
Highlights
The following highlights from the field survey are
presented to give a composite picture of the observa-
tions made during the land application site visits:
1. Communities generally use their land applica-
tion system on a continuous basis. Food process-
ing plants, the predominant industrial users of
the system, generally use discharge-to-land sys-
tems for three to eight months per year.
2. Ground cover utilized for municipal systems is
divided between grass and crops. Industries gen-
erally use grass cover.
3. Land application systems are generally used on a
daily basis, seven days per week.
4. Application rates for crop irrigation are very
low in terms of inches of water per week. Two
inches or less was commonly used. (Two inches
per week equals 48,000 gallons per acre per
week.)
5. Many types of soils were used, although sand,
loam and silt were the most common classifica-
tion given. Two systems using applications over
many feet of sand were applying up to eight in-
ches per day once a week, and one system on
clay was applying a daily rate of 0.1 inch.
6. Most operating agencies, municipal and indus-
trial, are planning to either expand or continue
their land application installations. The few
examples of systems which had been abandoned
were due to either the desire to make a higher
use of the land, or because of reported overload-
ing and incompetent operation of the land appli-
cation facilities.
7. Industries surveyed generally treat their total
waste flow by land application. Practices of
municipalities varied from less than 25 percent,
to all the wastewaters discharged.
8. Secondary treatment is generally, but not al-
ways, provided by municipalities prior to land
application, often times accompanied by lagoon-
ing. Industries using this technique frequently
treated their process wastes by screening only.
9. Spray irrigation is the most frequently used (57
facilities) method of application, although most
municipalities use more than one method. Ridge-
and-furrow irrigation is used at 23 facilities and
flooding irrigation by 34 systems. Industry gen-
erally used spray irrigation.
10. Land use zoning for land application sites is pre-
dominantly classified as farming, with some resi-
dential zoning in contiguous areas.
11. Wastewater generally is transported to the appli-
cation site by pressure lines, although a number
of municipalities are able to utilize ditches or
gravity flow pipelines.
12. Many municipal land application facilities have
been in use for several years—more than half for
over 15 years. Industrial systems generally have
been in use for a lesser period of time.
13. Renovated wastewater is seldom collected by
underdrains; rather, evaporation, plant trans-
piration, and groundwater recharge take up the
flow.
14. Land application facilities generally do not
make appreciable efforts to preclude public ac-
cess. Residences are frequently located adjacent
to land application sites. No special effort is
made to seclude land application areas from
recreational facilities and from those who use
these leisure sites.
15. Monitoring of groundwater quality, soil uptake
of contaminants, crop uptake of wastewater
components, and surface water impacts is not
carried out with any consistency.
Overview
In order to present all of the details and data re-
lating to the conduct of the studies, and to explore
the influence of possible factors influencing the han-
dling of sewage from many sources, at many sites, and
with many and diverse methods of application, the
APWA report has resulted in a rather large docu-
ment.
Among other things, the report has been compiled
to answer the inquiries of the U.S. Environmental
Protection Agency from other U.S. Government
agencies, municipalities, industries and engineering
consultants. The total report is valuable, not because
of its size but due to its contents. This is the first time
some of this data has ever been assembled, evaluated
and reported. It will become available from the U.S.
Government Printing Office in the autumn of 1973
and from the National Technical Information Service
(NTIS) of the U.S. Department of Commerce.
This overview is for those who require a brief sum-
mary of the contents of the American Public Works
Association report, entitled, Survey of Facilities Using
Land Application of Wastewaters, and an equally
concise evaluation of the principles, practices and
performances of the land application systems now in
service in the United States and in certain foreign
countries. Summaries of the basic intent and informa-
tion contained in each Section of the report are pre-
sented as well as a demographic evaluation and a dis-
cussion of the fate of materials applied to the land.
The sixteen conclusions drawn from the study
serve to verify the relative success of present land ap-
plication systems for supplementing groundwater
sources; providing economical means of effluent uti-
lization where discharge to surface waters would be
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12
RECYCLING MUNICIPAL SLUDGES AND F.FFLUFNTS
excessively difficult and costly; affording augmented
effluent quality improvement by soil uptake of constit-
uents which would adversely affect receiving water
quality; offering opportunities to enhance crop
growths and silviculture; and augmenting indigenous
water supplies for recreational and aesthetic pur-
poses.
Successful application of effluent wastewaters to
land areas is not without its problems. This manage-
ment technique is not a universal panacea.
The need for public acceptance of land application
methods is strongly advocated, particularly for pro-
posed installations covering large volumes of flow to
extensive acreage in relatively densely populated re-
gions. Over and above the problem of neutralizing
the aesthetic and psychological objections to any di-
rect or indirect contacts with wastewaters or waste
residues, unfounded fears of virological or pathologi-
cal infections must be overcome by carefully planned
and effectively executed public education programs.
This public relations problem emphasizes the rec-
ommendation that irrefutable findings on the pres-
ence or absence of health hazards in land application
practices must be defined and reported before guide-
lines for this method of wastewater effluent manage-
ment are promulgated. Guidelines are soon inter-
preted as "the law" rather than sHggi'sti'd criteria.
This gives credence to the sound suggestion that for-
malization of "guidelines" be deferred until "interim
evaluation procedures" are published and given the
opportunity to bridge the gap between today's rather
limited use of land application systems and any great-
ly expanded utilization of this treatment-disposal
procedure in the future.
The Study - Section II
The studies conducted by the American Public
Works Research Foundation on behalf of the U.S.
Environmental Protection Agency were planned and
consummated to produce the fundamental informa-
tion needed to give validity to the intent of Section
201 of the 1972 Amendments to the Water Pollution
Control Act such as;
• Affirmation of design and operational data for a
large number of U.S. installations in various climatic
regions, handling wastewaters of various types and
volumes; by various methods of application; for dif-
ferent purposes; on various types of soil, ground
cover and cropping; and demonstrating different
local environmental conditions and monitoring prac-
tices.
• Collection and interpretation of similar data on
foreign installations where land application has been
in effect for longer periods and under varying condi-
tions.
• Collation ol bibliographic rccoids .nul ivlcien
ces on every conceivable facet ol land application.
including design, operation, physical, chemical,
pathological, virological, parasitic, aesthetic, hydro-
logic, agricultural, herbicultural, silvicultural bene-
fits and detriments, and other related matters.
• Evaluation of all data in terms of practical inter-
pretation of their meaningful answers and guidelines
to land application practices.
The studies, in great measure, achieved these goals.
Survey Investigations - Section III
On-site, in-depth investigations of more than 67
community and 20 industrial land application sys-
tems were carried out by trained engineering special-
ists. The 87 installations designated provided data of
significance. These sites were chosen to be represen-
tative of national experiences with varying types of
wastewaters, applied to varying types of soils, ground
cover and other indigenous conditions under diverse
climatic conditions.
To augment the findings of the on-site surveys, a
mail investigation of similar land application sites
was carried out, covering the same study subjects ex-
plored by the field study team. Significant data were
obtained tor approximately the same number ol
municipal and industrial installations covered by the
field studies. Five climatic zones, each with their own
temperature, precipitation, humidity and seasonal
characteristics, were designated. Evaluation of survey
findings was interpreted on the basis of the impact of
climatic conditions on wastewater application to land
areas and other factors influenced by meteorological
phenomenon.
The demographic, geographic, geologic, hydro-
logic and other factors and impacts of land applica-
tion practices, procedures and performance are dis-
cussed in this section.
The findings of the survey offer evidence of accept-
able operating experiences, which should be useful in
guiding future land application decisions. An impor-
tant finding, among all of the diverse conclusions that
can be drawn from field and mail survey data, is the
fact that 90 percent of communities and 95 percent of
industries making use of land application methods
plan to continue their use; nearly 50 percent of com-
munities and one-fifth of the industries contemplate
increasing or expanding their systems. If the "proof of
the pudding" is in the performance, the approval of
users is the final appraisal of the land application
technique.
The study indicated that existing land application
systems are serving, predominantly, in relatively
small communities and industrial sites, in terms of
population and flow loadings. Future applications
-------
LAND APPLICATION
13
may involve larger loadings, greater irrigation areas
and greater land values, but the expansion of facili-
ties may represent an orderly enlargement of scope
and a manageable increase in costs. It is significant
that the costs involved in existing land application
systems apparently lie within the capabilities of
smaller communities and industry installations.
Choice of this means of wastewater disposal has been
based on various factors: need for supplemental irri-
gation water; augmentation of groundwater resour-
ces; simplicity and economy of providing required
degrees of treatment; problems of excessive cost of
providing treatment and outfall lines to distant points
of effluent discharge into suitable receiving waters;
and merely "to get rid of the sewage" in a convenient,
trouble-free manner that is acceptable to the com-
munity.
The findings of the survey are so manifold and
technological that any attempt to capsulate them
would hinder their value and endanger their interpre-
tation. The following points are borne out by the re-
port: existing practice stresses land application of
treated effluents, not raw wastewaters; the percentage
of land application acreage frequently represents
only a portion of the land reserved by the owners for
their systems; application periods may vary from one
month to twelve months a year, and from one to
seven days a week, depending on climatic conditions,
need for land application for surplusage flows, sea-
sonal industrial processing, such as in the food indus-
try, and other local factors; land values are relatively
low, zoned for either agriculture or residential uses,
often in undeveloped areas, and subject to minimal
degradation of value due to use for irrigation pur-
poses; all types of soil are utilized, with sand, clay
and silt most favored; groundwater interference prob-
lems influence choice of sites and, after choice of un-
affected sites, cause minimal difficulties with land ap-
plication methods; predominant wastewater distribu-
tion methods are spray irrigation, overland flooding
irrigation and ridge-and-furrow irrigation.
Use of the irrigated land varies with the owner's
needs and dictates, from no ground cover to grass
cover, cultivated crops and forested areas. Grass is
the most common ground cover in community sys-
tems. It is evident that the cropping value of supple-
mental irrigation with wastewaters and their nutrient
components is not universally utilized.
Rates of application of sewage effluents to the
land, and duration of uninterrupted application vary
from 0.1 inch per day to over 1 inch per day, with
varying periods of irrigation and resting. The most
commonly used application rate is two inches per
week. Few systems are over-stressed by such loadings;
it is apparent that increased rates of application
could be practiced without jeopardy to the system or
the environment, and with more effective and eco-
nomical utilization of assigned acreages. The follow-
the-leader trend in application rates is apparent; pro-
posed guidelines—either tentative or final—would do
much to establish more rational application rates,
based on facts rather than blind adherence to the ac-
cidental or arbitrary rates used by other researchers.
Little concern and protective measures have been
shown for the deterioration of the environment in ap-
plication areas, or to the impact on contiguous lands
and their occupants. Security provisions are not uni-
versally used to protect against intrusion of trespas-
sers or against the dispersal of on-site conditions to
surrounding land areas. Fencing and patrolling is not
universally practiced; buffer zones to isolate land ap-
plication areas and impede dispersal ol aerosol sprays
are used but no common practice is in effect; moni-
toring of groundwater, surface water sources, soils,
crops, animals and insects is practiced in some loca-
tions and minimally used in others, often dependent
solely on the requirements of public health authori-
ties.
It is hazardous to characterize the above thumbnail
findings as truly representative of the practices and
experiences disclosed by the survey. Similarly, these
factors do not represent all of the disclosures of the
study. They do however, give indication for those
who will not study the full text and details of the
comprehensive investigations explored in the full re-
port, that land application methods have been found
to be workable and relatively amenable to the local
environment, even under control and regulatory pro-
cedures which must be improved in all future land
application practices. The future will require more
complete supervision of land application sites, sup-
ported by definitive proof of the capabilities of such
systems to serve as wastes handling facilities worthy
of the term "alternative" techniques.
Opinions and Regulations of State
Health and Water Pollution Control
Agencies - Section IV
The survey conducted by APWA with State health
and water pollution control agencies indicated that
most State agencies have no set policies on this phase
of wastewater handling or attendant environmental
impacts, do not impose specific conditions on instal-
lations, seldom inspect existing systems, and seldom
require monitoring procedures and the filing of offi-
cial reports on operation.
Only four States reported rules governing the types
of crops that can be grown on sewage-irrigated lands.
The few agencies which invoke restrictions of this na-
ture specify the quality of effluents applied to land
areas. Of 27 State control agencies which participated
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14
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
in the data-gathering program, a maximum of 25 per-
cent involved themselves with any single item of the
11 guideline criteria covered by the opinion survey.
In defense of this record of irrelevance with the
land application practice, it must be said that some
States have few such installations and even fewer
have installations of any major significance. In addi-
tion, States contend that they have been deeply in-
volved with the control and regulation of conven-
tional sewage treatment facilities and stream quality
protection. Shortage of qualified personnel has been
offered as the reason for absence of attention to the
installation, operation and monitoring of land appli-
cation installations.
In the absence of formal State regulations, some
agencies have used unofficial staff opinions as the
basis for land application decisions. Similarly, each-
case-for-itself decisions on health hazards have been
invoked or expressed by State health agencies but a
minimum of translation of such policies into specific
regulatory actions was disclosed by the survey.
Summary of Foreign Experence -
Section V
Data from such widely located countries as Ar-
gentina, Australia, Belgium, India, Israel, Hungary,
and Mexico confirm the use and value of the land ap-
plication technique for various purposes, for a variety
of growing crops, under diversified conditions, and
with different results. Enhancement of soil productiv-
ity, through the mechanics of supplemental irrigation
with waste water and the enrichment of soil with the
organic constituents of sewage and industrial proc-
essing waters are widely acknowledged.
Health hazards have been studied in various coun-
tries and protective measures have been invoked.
Some countries, such as water-short Israel, utilize
\\astewaters for irrigation purposes—where over 100
systems are in service, but they tend to avoid the use
of raw, untreated sewage and contact with crops that
are eaten raw by humans or domesticated animals.
On the North American continent, the most
dramatic land application system on record is in Tula
Hidalgo, Mexico, where lands operated by the Mexi-
can Federal Department of Agriculture are assigned
to Ejidos, heads of families, in units of limited hec-
tares. On 47,000 hectares, equivalent to 115,000
acres, some 1,476,000 metric tons of food products
were grown in 1971. Approximately the same tonnage
was produced in 1972. Additional arid land is avail-
able for cultivation when additional wastewater from
Mexico City becomes available. Currently some 570
million gallons per day of raw untreated sewage flows
by canal to this area, 95 percent of which reach the
cropland. During the rainy season there is an addi-
tional storm water flow through the same canal, most
of which is impounded in a series of dams for use dur-
ing the dry season for cropland irrigation.
In England the Herefordshire facility has had over
20 years experience irrigating liquid digested sludge
containing about three percent solids. Technically
this land application system is more related to sludge
than to sewage effluents, but its long and successful
experience confirms the feasibility of that method of
land application of wastewaters. There is a non-
technical 16 mm color film, entitled, Wealth from
Waste, which shows the Herefordshire operations.
Guidelines for Implementation of Land
Application Systems - Section VI
The survey provided many guidelines that could
be translated into "do's" and "don'ts" in land appli-
cation procedures. In addition the literature searches
brought added criteria to light, confirming the basic
facts evolved from the survey. From these informa-
tion sources and others, the report suggests guidelines
for the implementation of land application systems.
For the guidance of the regulatory administrator
staffs, decision-makers, designers and owners of fu-
ture land application installations, some tentative
procedures have been presented as they may be affec-
ted by climatic meteorological phenomenon; avail-
ability and location of land areas suitable for waste-
water application; rates of application; types of soils,
crops and ground cover; methods of application and
their relationship with geological, topographical and
hydrological conditions; types of wastewater pre-
treatment to assure proper and safe land application;
capital and operating costs; monitoring and health
protective measures; and other related aspects of
system planning and execution.
References have been drawn from all possible
sources to support the tentative parametric proce-
dures outlined in the guidelines. The listed criteria
are not presented as "standards"; this would be im-
properly anticipatory of the next official step which
must be taken to distill from this study and the other
parallel investigations sponsored by the United States
Environmental Protection Agency on land applica-
tion techniques. Rather the guidelines are offered as
suggested criteria, a necessary input into the overall
fund of information upon which eventual official
guidelines must be based. As mentioned in the Over-
view this gives credence to the suggestion that formal-
ization of guidelines be deferred until "interim
evaluation procedures" are published.
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LAND APPLICATION
Placing Land Application of Effluents
In Perspective: An Interpretation - Section
VII
This section stresses the importance of placing
land application techniques in their proper perspec-
tive, and interpreting the alternative "pluses" and
"minuses" on the basis of local factors and local
needs.
It is evident that an "alternative" must be com-
pared with something for which it is an alternative.
Thus, the determination of the choice of wastewater
utilization process must be based on a full-dimension-
al decision; and that decision must stem from placing
the land application process into the proper perspec-
tive with itself and with other means of managing
wastewaters.
When viewed in this light, land application tech-
nology is not a panacea for all wastes, in all areas,
under all circumstances. It is not a "quick and easy"
means of getting rid of unwanted wastewaters. It in-
volves adequate pretreatment, effective operational
procedures, rigid monitoring controls and rational
cost evaluations. As a substitute for the return of
waters into the drainage basins from whence it ori-
ginally came, it can affect the "cycle of water" and
create an imbalance in the water resources of a re-
gion. Land application can no longer be compared
with disposal of wastes by dilution; just as conven-
tional wastewater treatment now involves high de-
grees of treatment, so land application must assure
that the soil will receive highly treated influent water
or that the soil will provide the equivalent of tertiary
treatment and removal of deleterious components by
biological-chemical-physical phenomenon. The ef-
fectiveness of land application must be judged by
what it accomplishes—not merely as a means of
eliminating the direct discharge of comparably well
treated effluents into receiving waters.
To fulfill its full possibilities and benefits, land ap-
plication must be examined from the standpoint of
what has become known as the "4-R cycle"—return
of wastewater to the local land rather than being lost
by stream flowage to downstream areas; renovation of
the wastewater by soil and vegetative actions; re-
charge of the groundwater resources which then be-
come the reservoir aquifer which feeds surface water
sources; and the reuse of wastewater either directly
off the land or via the groundwater reservoir. Prac-
tical examples of these land application benefits are
available; they must be placed in proper perspective
with the needs and potentialities of the area in which
a proposed land application project will be construc-
ted as an alternative to conventional wastewater
treatment works.
Demographic Evaluation of Land
Application Techniques
Demography is the science of social statistics.
Wastewaters are the product of people and of indus-
trial production in an urban industrial society. The
nature of wastes produced by community life and in-
dustrial processing and the amounts of such waste-
waters are affected by regional conditions and their
impact on life and living processes. Automatically
then, the manner in which wastewaters are handled
and disposed of is influenced by demography, or re-
gional, environmental needs. For example, the degree
of sewage and industrial treatment in the past was in-
fluenced by the water resources needs of regional
areas and how regulatory bodies interpreted these
needs to protect the natural environment and pre-
serve public health and safety. Over and above the
natural setting for any region, policies were and will
continue to be, affected by population densities,
water needs, public desires and antipathies, and other
factors. This represents demography in action.
If it were possible to relate the applicability of
wastewater management on land areas to such factors
as climatic conditions, population and population
densities, economic-social patterns, and similar
demographic parameters, these would serve as impor-
tant guides for the choice of this alternative method
of wastewater treatment and utilization vis-a-vis to-
day's conventional treatment standards and the ad-
vanced degrees of effluent quality that will be re-
quired in the future. If such relationships could be
established, based on the findings of the APWA Re-
port, or by parallel investigations now sponsored by
EPA, the viability of the land application technique
could be verified or clinically questioned.
The factors involved in a full demographic evalua-
tion of land application practices appear to be too
numerous, too complex and too interwoven to be
capable of clarification by the current APWA study.
Many of the factors are too intangible to be ex-
plained by basic survey data; the type of study para-
meters used in the current study could not include
such incomprehensible implications. But the study
did involve the relationships between land applica-
tion and climatic conditions, and concurrent rela-
tionships involving urban populations and densities,
industrial operations, local ecological conditions and
other indigenous factors (See Figure 1).
Climate is a major factor in the applicability of
land application procedures, on the purpose and con-
tinuity of operation, and on the performance of this
alternative technique. In recognition of the impor-
tance of climatic conditions, the study was based on
the choice of site investigations in five climatic re-
-------
RECYCLING MUNICIPAL SLUDGES AND KFFLl KNTS
gions of the United States and evaluations were aimed
at determining the impact of the specific zonal
meteorological characteristics on every phase of the
study (Figure 2).
DEMOGRAPHIC EVALUATION
1. Climate Conditions
2. Size of Facility
3. Continuity of Operations
4. Methods of Distribution
5. Land Availability
Hgurc 1 Demographic I valuation.
CLIMATIC ZONES
Figure 2 Climatic Zone;..
Broadly characterized, Zone A (mid and south
Pacific coast) is an area of dry summers and mild wet
winters; Zone B (the southwest) is an arid region, with
hot. dry climate; Zone C (southeast-Gulf coast-At-
lantic coast and Pacific northwest) experiences hot
wet summers and mild winters; Zone D (east-contin-
ent and northeast Atlantic coast) is subject to humid
weather, with short winters and hot summers; Zone E
(mid-continent and far northeast) is a humid area,
with long winters and warm summers.
While climatic conditions have the most significant
impact on the land application principle, other fac-
tors have potential bearing: size of the community
and the industry; the volume of wastes flow; the
population contributing sanitary wastes plus the
population equivalent of the industrial wastes con-
tributed to the municipal sewer system; the availabil-
ity of open land for irrigation use; the land-use zon-
ing of the region; the cost of land; the type of crops to
be grown with supplemental irrigation and the mar-
ket needs and demands for such crops, the ground-
water depth and quantities, and their use for \\atei
supply purposes, protection against salt water intru-
sion into aquifers and other functions; the nature of
the soil; the proximity of surface waters which can
become recipients of conventionally treated effluents;
and other correlated circumstances of local or in-
digenous nature.
It is not difficult to rationalize the effects of these
climatic-demographic conditions on land application
practices, and conversely, the impacts of land appli-
cation on these environmental conditions. It is diffi-
cult, however, to translate the findings of the subject
into these relationships. Efforts have been made to
draw every possible relationship between these vari-
ous factors hut the findings are often too indetermin-
ate to warrant such translations.
The following highlights can provide valuable
guidance for decision-makers and designers of land
application systems, even though they are not always
affirmed and confirmed by study findings.
Climatic Conditions
The 67 community systems and 20 industrial land
application sites covered by the on-site visits, and the
comparable numbers of such installations covered by
the mail inquiry, were representative of the actual
total projects in each of the five climatic zones. The
major number of community systems surveyed was
located in Zones A and B, with California sites pre-
dominating. These two zones represent dry and arid
conditions which make supplemental water resour-
ces—reused water in the form of effluents—a pre-
cious commodity. No industrial sites in these zones
were surveyed by on-site investigators because mini-
mal use of land application techniques is made by
local industrial installations. In lieu of such indus-
trial irrigation projects, communities in Zones A and
B accept industrial wastes into public sewers and on-
to publicly owned application sites in the form of
population equivalent loadings.
In Zones C, D, and E, industrial sites were sur-
veyed because the use of land application is practiced
more generally in these parts of the nation. The in-
dustries involved are primarily food canning-process-
ing factories, dairy processing plants, pulp and paper
mills, and organic chemical manufacturing firms.
The differentiation between the zonal incidences of
community systems and industry sites is explained, at
least in part, by the needs for supplemental water and
the uses for such water. Thus, climatic water-short
and water-rich areas dictate the retention of sanitary
wastewaters in the areas which produce them, or
whether to permit them to flow away downstream in-
to other receiving watersheds and water basins.
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LAND APPLICATION
17
In regions A and B, water is in relatively short sup-
ply, due to dry summers and year-round aridity, and
wastewaters are often times considered by communi-
ties as a valuable commodity for land irrigation, for
groundwater augmentation, and for use for such an-
cillary purposes as golf course and highway median
watering and the creation of recreational water facili-
ties. Industries in these areas however, as in other
areas, are less concerned with such beneficial uses of
wastewater and may not practice land application;
they may use this management procedure primarily
tor the purpose of "getting rid" of such effluents in
the cheapest and simplest manner without adversely
affecting the environment.
This brings the matter of wastewater, or used
water, economic and ecologic value and utilization
into focus as the determining factors in the practice
of land application. In arid regions, land application
offers strong incentives. In wet, humid regions water-
husbanding is not a vital motivating reason for land
application installations; but such motivation can be
tound in the economies of producing high-quality ef-
fluent by means of the "free" purification capabilities
of soil. Whether planned as a water resource conser-
vation procedure or not, the ultimate fate of waste-
waters applied to land areas by spray irrigation and
surface application, such as, ridge-and-furrow
methods is a means of enhancement of the local
groundwater reservoir. The fact that 85 percent of
the water stored in the United States is contained in
subsurface aquifers adds significance to this waste-
water fate.
Climatic, geographic and geologic conditions have
other influences on the choice of wastewater disposal
systems. Inland areas that have no convenient receiv-
ing waters may find it cheaper to apply wastewaters
to the land rather than constructing long, expensive
outfall lines from their treatment plants to suitable
discharge points. On the other hand, the water-cycle
imbalance which may occur in local waters by taking
water supplies from them and not returning waste-
water back to the same rivers and lakes may place a
negative aspect on land application procedures. This
type of water resource imbalance does not apply to
coastal waters.
The relationship between hard winters and land
application systems is obvious. In areas where full-
Near irrigation can be practiced, land application
would have greater applicability than where adverse
winter conditions would make irrigation inappropri-
ate or inefficient. While land application is practiced
in some ice, snow and sub-freezing conditions, opti-
mum conditions are represented by year-round mild
weather such as is experienced in Zones A, parts of B,
and in C.
Similarly, the relationship between climatic condi-
tions and holding pond capacities is equally under-
standable. Where seasonal cessation of land applica-
tion is necessary, the principle of "not one drop of
wastes into water resources" impel Is the construction
and use of adequate holding facilities. "Adequacy" is
a relative term; 31 percent of community and indus-
trial systems use ponds with capacities of five days or
less. In Zones A, B and C, 75 percent of the sites have
holding capacities of less than 30 days, or less than
needed for a full winter season. One installation in a
cold zone provides a 50 million gallon pond for a
daily flow loading of 0.5 mgd.
Of some significance, if not as perinent as other
seasonal conditions, is the amount of rainfall in
humid areas which may impede soil absorption of ap-
plied wastewaters and require the use of flow-equali-
zation or flow-holding of excess waters until required
rates of application can be reinstated. As stated,
where rainfall is generally adequate, if not always
predictable, land application for enhancement of
crop growths, forest growths and groundwater aug-
mentation is not the dominant reason for the choice
of this wastewater management technique.
While the survey studies brought these climatic re-
lationships into focus, they did not always provide
positive proof of these effects and impacts. This does
not detract from the validity of the above observa-
tions. No attempt has been made to draw all possible
climatic-environmental relationships with land appli-
cation principles and practices; however, the ration-
ale is adequate to demonstrate that there is a direct
correlation which must be considered before choice
of wastewater management is made for each in-
dividual project. No set standards can be established;
each case will require its own relationship evaluation.
Size of Wastewater Facility
In the case of publicly owned systems, the popula-
tion served is translatable into volumetric and quali-
tative loadings. For industries, the flow loading is a
factor of volume and population equivalency of the
organic constituents, as measured by BOD, COD,
suspended solids and other significant parameters.
The survey indicated that some outstanding large
community land application installations have been
in service in the United States and foreign countries.
However, the major percentage of current operating
installations are in the smaller-size range.
The on-site survey disclosed that 73 percent of
communities studied have land application capacities
of under 5 mgd; the mail survey covered no commun-
ity systems with over 10-mgd capacity. Industry in-
stallations covered by the on-site survey were all un-
der 5-mgd capacities; the mail-surveyed installations
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18
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
were all under 10-mgd size. It is conjectured that the
small cities and industries have found land applica-
tion within their economic range and that adequate
conventional treatment would have been more costly.
Size factors are numerous but few showed defini-
tive relationships with other land application site
acreage parameters. The area used for irrigation ap-
plication varied without basic reason from the total
acreage owned by the community or industry. In
some cases the major extent of the area is used for
distribution; in other instances only a portion is so
used, the rest of the acreage being devoted to holding
ponds, buffer zone and general isolation of sites.
The size of the area varies, naturally, with the
volume of flow applied, the nature of the soil and its
absorptive character. The effect of climatic condi-
tions, such as rainfall, humidity and temperature, on
irrigation area acquired by communities and indus-
tries is minimal, despite any impression that such a
direct relationship should exist. No specific trend was
found in buffer zone regulations and usage. The open
land available for such buffering or isolation facili-
ties is undoubtedly influenced by State regulatory
agency requirements and the type of distribution sys-
tems used. (Spray irrigation tends to be associated
with buffering acres and plantings to impede the off-
site dissemination of aerosol mists and particulates.)
Continuity of Operation
The relationship between continuity of wastewater
application, on a days-per-week or a months-per-
year basis, and land acreages used for land applica-
tion was found to be indeterminate. Continuity of
operation appeared to be dictated by other factors
than availability of site acreage. It is obvious that
rates of application should have a bearing on the land
areas required, particularly on sites that are limited
in size and not over-generous in dimensions. While
the analysis of study data does not disclose this rela-
tionship, it is undebatable since the failure of irri-
gated land to handle distributed wastewaters for
planned periods will necessitate the resting of such
areas and the immediate utilization of other equiva-
lent acreages to replace the overloaded or ponded
soil plots.
If wastewater production is in effect for longer
weekly or monthly periods and pond storage capacity
is not available to retain excess flows, irrigation areas
may be affected by the requirement that direct appli-
cation of produced flows must be provided. Similarly,
the land-need requirements for any site will be in-
fluenced by whether the system will function on a
twelve-month basis or shorter yearly periods
(Figure 3).
Climate
Zone
A
B
C
D
E
% Year-round
Community
76
63
56
71
67
Industrial
50
56
30
Figure 3' Continuity of Operation
Communities tend to maintain yearly continuity of
land application more completely than industries;
broadly interpreted, communities operate full-year at
60 percent of installations, and industries at 40 per-
cent of sites. The relationship between climate and
continuity of irrigation was partially clarified by the
study, despite the fact that positive patterns were not
confirmed. The on-site survey-interview procedures
used in the study disclosed that twelve-month con-
tinuity of community operation for Zones A, B, C, D
and E was practiced in 76, 63, 56, 71 and 67 percent
of sites, respectively, while industrial systems showed
similar year-round irrigation service in Zones C, D
and E of 50, 56 and 30 percent of sites, respectively.
The mail survey showed that industries in Zones A
and B (not surveyed in the on-site program) operated
on a twelve-month basis at 100 percent of the sites in-
volved, with 100 percent of the Zone C community
installations functioning on a full-year basis. Thus,
the zonal factors showed little effect of widely diver-
gent climatic conditions on whether systems func-
tioned without cessation.
Full-week service seemed to be dictated more by
the actual purpose of land application than by other
factors. Full-week irrigation was found to be more
common than when crop irrigation was practiced
than when wastewater disposal onto grass-cover
lands was utilized for groundwater augmentation or
for the simple purpose of effluent disposal. Applica-
tion rates and continuity of irrigation were, surpris-
ingly, unaffected by soil types.
Methods of Distribution
The relationship between the method of applica-
tion and climatic conditions was brought into focus
by the study. In general, spray irrigation is more
commonly used in humid areas than in arid sectors;
and surface application techniques, such as ridge-
and-furrow irrigation and overland irrigation, are
more frequently utilized in arid regions. Zones A and
B were characterized by surface application sites.
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IAND APPLICATION
19
The relationship between size of site and type of
distribution used showed a trend of more or less
specificity. Smaller sites were served by twice as
many spray systems as surface application facilities.
Larger sites, over 1,000 acres in size, were usually
equipped with surface application systems; intermedi-
ate-sized sites, from about 100 acres of 1,000 acres,
utilized spray and surface application systems about
equally. In surface application installations, so-called
overland flooding which depends on sheet-flow ac-
tion has been used more frequently than ridge-and-
furrow distribution.
No specific correlation was found between dis-
tribution methods and soil types, but some general-
ized patterns were evaluated: spray irrigation is more
commonly used on loam, silt and clay lands; spray
and surface application methods are generally used
equally on more granular soils. Surface application
methods were found more frequently on crop lands
or on unplanted, non-cover areas. Spray irrigation
was found more frequently on crop lands and
forested acreages. Community sites handling under 1-
mgd flows were most commonly grass-covered, while
larger areas of over 1-mgd capacity generally stressed
crop growth. Forest irrigation was practiced more
frequently in humid areas than arid regions, probably
because tree growth is more common in the humid
climatic regions. Cropping on arid region lands is
relatively common, indicating the value of waste-
water for supplemental irrigation.
Groundwater depths are a dominant factor in
choice of sites but, once acquired, these application
lands experience minimal impacts on choice of appli-
cation methods and on operation performance. Ob-
viously groundwater depths are greater in arid re-
gions and are less of a factor in choice of land appli-
cation sites. Application rates, while not consistently
influenced by climatic conditions or soil character,
and while varying minimally from the almost tradi-
tional level of one-half inch per day and two inches
per week, are influenced by aridity and high humid-
ity-precipitation conditions.
Land Availability, Land Use
and Land Value
A direct relationship between demographic cri-
teria and land availability, zoning use and acreage
price is unavoidable. The first requirement of a land
application system is land. It must be available in rea-
sonably close proximity to the source of community
or industrial wastes; the land must be useable for
wastewater application by zoning and other use regu-
lations; the price must not be prohibitive.
These conditions are most commonly met in areas
of low population density where open lands are avail-
able, and where undeveloped and properly zoned
properties can be acquired at relatively low cost. This
is why the survey showed the predominance of land
systems in use by small communities and relatively
small industries, and land prices ranging basically in
the under-$500 per acre price level. Areas of the na-
tion will become progressively more densely popu-
lated because over a million acres of rural lands are
absorbed annually in urbanization and related facets
of community growth. The availability of nearby
lands, zoned for agriculture or residential purposes,
and priced at low enough levels, will become a great-
er problem for users of land application systems. The
cost of long-distance wastewater transmission will
become an important factor in determining the
economic feasibility of land application for waste-
waters.
The impact of land application installation on
neighboring areas and their residents can be in direct
ratio to population density. While existing systems
have demonstrated their ability to be "good neigh-
bors" to residents living as close as 500 feet of appli-
cation site, this close proximity may not be good
practice in all cases. Reported complaints have been
minimal against present installations despite the fact
that, for example, 20 percent of community systems
in Zone A are located less than 500 feet from the
nearest neighbors and 22 percent are similarly lo-
cated in Zone B. Industrial sites are located in Zones
C, D and E within 500 feet of residences in 10, 10 and
21 percent of the cases investigated, respectively.
The relationship between local demographic con-
ditions and land application system monitoring is ob-
vious. The degree of monitoring was found to be less
related to zone climatologicai conditions than to
State health and water pollution control regulations
in the limited cases where such governmental stipula-
tions are imposed. It is understandable that increasing
population intrusions in an area, and the density of
the residential population, will dictate that closer at-
tention should be given to the impacts of land appli-
cation on land and water resources and on persons
exposed to actual wastewater, sludge residues, spray
mists and animals and insects which come in contact
with irrigation liquids and vegetative growths. The
frequency and location of monitoring points, such as
test wells and other sampling facilities, and the extent
of monitoring parameters will be intensified in the fu-
ture to satisfy actual hazards or the psychological im-
pressions of local residents.
Site security measures, such as fencing may be re-
quired and buffer zones may be specified. Operation
and maintenance costs will react to all such monitor-
ing and security requirements but the reasonable cost
levels for present systems could be increased without
seriously affecting the feasibility and economy of
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20
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
land application techniques. Future wastewater treat-
ment works, particularly those requiring full second-
ary treatment and processing to remove such com-
ponents as phosphorous, nitrogen, trace metals and
organic pesticides, will require similar augmentation
of present specific laboratory control and site safety
and security measures.
Fate of Materials Applied to the Land
To complete this extended summary of the land
application of. wastewaters a review of the fate of
applied materials is presented to round out the infor-
mation which has been presented. Reference is made
to two papers entitled. Experiences with Land
Spreading of Municipal Effluents, and Fate of Mater-
ials Applied, prepared by Richard E. Thomas, Soil
Scientist, Robert S. Kerr, Water Research Center,
Environmental Protection Agency, Ada, Oklahoma.
For the future applicability of land utilization of
wastewaters, it is important to know with some meas-
ure of certainty what the fate of wastewater compon-
ents will be.
The materials contained in wastewaters are remini-
scent of the origin of these flows—either sanitary,
sanitary and combined storm water, industrial proc-
ess water, or combinations of sanitary and industrial
wastes. Since the application of raw wastewaters onto
land areas is not contemplated under the definition of
this alternative waste management technique, all such
wastes have been subject to some degree of pretreat-
ment before they are applied to land. The purpose of
monitoring of influent flows onto land areas is to as-
certain the composition of the wastewater after the
stages of pretreatment provided.
A classification of wastewater materials could be:
suspended materials; major plant nutrients; and other
constituents. Another delineation of the wastewater
components, based on the actual physical nature of
the substances is: suspended solids: colloidal solids;
dissolved organic materials; and dissolved inorganic
substances.
The fate of these substances during the process of
land application will vary with the type of distribu-
tion system, the nature of the soil, the rate of applica-
tion, the climate, the resting periods, and the location
and proximity of the groundwater aquifier and the
surface water source which receives runoff from the
site. The phenomena involved include: the physical
condition of entrapment or mechanical filtration; the
biological, biochemical, electrochemical and other
manifestations in and in contact with the soil; eva-
porative factors; atmospheric oxidation; bacteriologi-
cal, germicidal, and bacteriophage or anti-contami-
nation reactions, and others which are not totally un-
derstood even by highly trained and experienced sci-
entists.
Suspended solids entrapped in the interstices of the
soil or adhering to soil particles by electrochemical
entrainment can experience biological oxidation and
decomposition into stabilized substances. The fate of
this suspended material can vary; it can remain in the
soil to form humus soil conditioning or nutritive ma-
terial or, in course media, it may be sloughed off and
percolated into lower soil depths or into the ground-
water.
Colloidal materials—solids of minute size which
may be able to filter through soil media—can be
coalesced or coagulated by electrochemical ag-
glomeration and then adsorbed onto soil particles.
The fate of this material, normally considered to
possess electrical charge, may parallel thai of true
suspended solids, by oxidation-digestion phenomena.
Accumulations in the soil may affect the rate of ap-
plication of subsequent wastewater loadings.
Organic dissolved solids may be utilized by plant
crops, retained in the body of the soil by chemical
fixation or other bonding phenomena or may be oxi-
dized by atmospheric reactions, in the course of air
contact with sprays or sheets of wastewater flowing
over the land.
A major concern is centered on the nitrogen and
phosphorous in wastewaters. The presence of these
dissolved constituents can influence the use of land
application systems in lieu of advanced treatment and
discharge into surface receiving water, primarily be-
cause they can act as "triggers" in the eutrophication
of surface waters. Similarly, if these materials can ad-
versely "fertilize" lakes, why cannot they be used to
fertilize land?
The fate of nitrogen and phosphorous will be in-
fluenced by many factors, including the type of
wastewater distribution system utilized, and the type
of ground cover and crops grown. The factors in-
volved in the different land application methods are
covered in excellent details in the above-referenced
papers, and it is not the intent here to explore these
manifestations beyond brief reference to the fact that
the fate of these two basic elements can be regulated
by proper practices to avoid serious effects on
groundwater or surface water sources. The ability of
soil to retain and fix phosphorous delivery to the soil
may be greater than the crop uptake ability to utilize
it. Fortunately, soil retention is able to prevent phos-
phorous intrusion into groundwaters that are ade-
quately deep for any effective land application site.
Nitrogen could enter the groundwater in concen-
trations that might exceed the safe levels of this ma-
terial in water for human consumption. However, the
ability of land application techniques to complete a
nitrification-denitrification cycle can be utilized to
prevent this fate, as in the spray-runoff technique. A
substantial proportion of ihe phosphorous contained
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LAND APPLICATION
21
in applied wastewaters in the same spray runoff proc-
ess could reach surface water sources unless steps are
taken to improve phosphorous removal by land con-
tact.
Other constituents of land-applied wastewaters
have fates that may influence the use of land methods,
either in favor of this alternative process or opposed
to its utilization. These include heavy metals, even in
trace amounts, pesticides and other organo-com-
pounds, and various salts. Evaporation and evapo-
transpiration of liquids from soil, vegetative surfaces
or water surfaces will not change the fate of these dis-
solved materials; the evaporative process parallels
the distillation phenomenon, in that the water is con-
verted to vapor or gaseous form and the solids are
thus concentrated in the soil or vegetation. Salts may
thus reach the groundwater by percolation and leach-
ing action. Heavy metals and pesticides can undergo
physical, chemical and biochemical interactions with
the soil, making land application an auxilliary means
of providing so-called "tertiary" treatment for waste-
waters, in lieu of more complex and more costly arti-
ficial wastes treatment processes.
To repeat the statement made above, the intent of
this dissertation on the fate of materials applied to
land areas is to point out that the soil and vegetative
forms do offer a "bonus" factor that must be given
consideration in determining the future of the land
application process. Current concern about the im-
pacts of nitrates, phosphorous, trace metals, pesti-
cides and other organic compounds on receiving
waters is sufficient reason for knowing more about
the fate of these objectionable materials in the land
application process. More remains to be known about
(hem, and about the way various methods of waste-
water distribution, various types of soil and topo-
graphic and climatic conditions, and other factors
and combinations of factors, influence their fate.
The fate of wastewater contaminants during the
land application process, in short, offers opportuni-
ties for beneficial use for soil and crop enhancement
which must be considered as a "plus" for this alterna-
tive technique. In addition, the capability of the land
application system to remove, modify and stabilize
pollutants which would require augmented process-
ing in conventional sewage treatment systems offers
another advantage for this alternative management
procedure. But, these benefits must be evaluated in
the light of whether the applied materials will in any
way adversely affect the water and soil environment
of the region where land application systems will be
utilized. Only through a weighing of the benefits and
hazards can the feasibility and applicability of land
application processes be properly judged for each
specific installation and each specific wastes prob-
lem.
CONCLUSIONS
1. Land application ofwistewiters from connnunitv
and industrial processing sources is practiced
successfully and extensively in the United States
and in many countries throughout the world.
Facilities investigated handled from less than 0.5
mgd, providing service for sixty days per year, to
over 570 mgd applied on a year-around basis.
2. Land application of wastewaters is practiced for
several specific reasons. Among the major rea-
sons were: to provide for supplemental irrigation
water; the desirability of augmenting ground-
water sources; excessive distances to suitable
bodies of receiving waters or extraordinary cost
to construct facilities to reach suitable disposal
sites; economic feasibility, as contrasted with the
cost of construction and operation of advanced
or tertiary treatment facilities; inability of con-
ventional treatment facilities to handle difficult-
to-treat wastes.
3. Present land application facilities generally are
not "stressing" the system. Many facilities were
found to be using effluent on a crop-need basis.
Even where efforts were being made to use land
as the only point of disposal, application rates
were generally conservative and the soil-plant
components of the system were not stressed to
limits of assimilation or used to their optimum
capacities, thus providing a large factor of
safety.
4. A variety of beneficial uses are being made of
wastewater effluents. Uses include irrigation of
parks, golf courses, cemeteries, college grounds,
street trees, highway median strips, sports
grounds, ornamental fountains and artificial
lakes. Wastewater effluents are also used to irri-
gate many types of crops, including grasses, al-
falfa, corn, sorghum, citrus trees, grapes, and
cotton. Forest lands are also being irrigated in
many areas. Groundwater augmentation to pre-
vent salt water intrusion is being practiced. In
Mexico, a wide variety of truck garden crops has
long been irrigated with effluent. Crops ap-
peared to benefit from both the nutrients and the
increased amount of water which is applied.
5. A large variety of potential opportunities for land
application of wastewater exist in many com-
munities. Wastewaters that are given a high de-
gree of treatment could well be considered for
irrigating large public and private facilities to
relieve the demand for irrigation with potable
water supplies. Golf courses, cemeteries, park-
ways, school grounds, parks, airports, planned
unit developments, green belts, forest preserves,
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
and marginal land all offer the useful applica-
tion of effluents to the land.
6. Sale of effluent for beneficial use has been gen-
erally unsuccessful. Few examples were found
where a public agency had been able to obtain
more than a token payment for supplying treated
effluent. In several cases it was reported that
land for the treatment plant had been given in
consideration of a right to all or a portion of the
effluent. Where an agency received a tangible
dollar return, it was generally based upon use of
both land and the effluent.
7. Successful operation of a land application system
requires the inputs from a variety of disciplines.
For many systems, the services of a geologist and
environmental engineer arc required. For system
designed to augment the indigenous crop water
requirements by supplemental irrigation, the ad-
vice and guidance of soils specialist will be
needed. For larger systems, social and behavior-
al scientists, as well as medical-health personnel
may be required to assist in evaluating and se-
curing acceptance of this alternative means of
disposal.
8. Operation of land application facilities can be ac-
complished without creating a nuisance or down-
grading the adjacent environment. The survey in-
dicated that a majority of the facilities were con-
ducted by well-trained personnel, aware of the
need for careful operation of the systems. Train-
ing, supervision, and adequate monitoring of
pertinent factors are necessary to ensure that
systems will not be over-stressed. If ponding on
the land is not allowed, odors will not be a prob-
lem. The hazard of creating other adverse effects
on the environment by discharging treated efflu-
ent on land is minimal.
9. Monitoring of land application facilities and ef-
fects has been minimal and mostly inadequate.
Few states appear to have taken an active role in
requiring use of monitoring facilities, apparently
because there was no direct discharge of efflu-
ents to receiving waters. Many of the municipal
systems surveyed had little or no monitoring, in-
asmuch as the effluent was being used only for
supplemental irrigation.
Industrial systems were generally better moni-
tored, but control in most cases cannot be char-
acterized as being adequate.
10. Environmental analysis of the effects of land ap-
plication facilities reflects a general improvement
of the environment rather than impairment of the
indigenous ecology. Many facilities were ob-
served where the effluent provided the only ir-
rigation water available. Land values for sites
with a right to such waste waters were greater
than that of adjacent land because crop and
forest growth was enhanced, and use of potable
water supplies reduced. No instances of health
hazards were reported from any existing facili-
ties, although the State of Delaware indicated
concern over potential virus transmission.
Farming and recreation potentials exist, as
well as improved habitat for wild life.
Treatment of wastewater prior to land appli-
cation has generally been dictated by the desire
to use the best practical means consistent with
available technology and to minimize any ad-
verse effects upon the environment. Land appli-
cation of wastewater, by eliminating direct dis-
charges of effluent into receiving waters, could
be regarded as satisfying the ultimate national
policy goal of "zero discharge" of pollutants.
11. i'.nergy requirements for land a/ypln at ion systems
may he an important consideration Reported
energy requirements for most advanced tertiary
treatment proposals are very high, as compared
to conventional treatment. Depending upon the
location and availability of land, energy require-
ments associated with land application tech-
niques may be substantially less than other
means of treatment and effluent management.
This factor deserves further evaluation.
12. The nature and quantity of receiving waters must
be carefully evaluated prior to diverting effluent
to land application. Few existing systems were
found that used underdrains to collect the reno-
vated effluent. Rather, the groundwater aquifers
received the flow. If a land application area is
adjacent to the receiving water, much of the
groundwater may serve to augment the flow into
the receiving waters by a gradual seepage into
the drainage basin. Elimination of direct waste-
water discharges to a stream could unbalance
the flow regimen associated with downstream
beneficial uses, inhibit desirable dilution of
waste discharge, interfere with the tempering of
thermal water discharges. Land application can
prevent the intrusion of saline waters into nor-
mally fresh water zones. The impact of effluent
diversion onto land areas with respect to the
basic principle of riparian water rights must be
considered where irrigation is planned as an al-
ternate to discharge into surface waters.
13. When wastewater is discharged to land and this
method is used as a means of advanced treatment
by natural means, the land must receive priority
for this use over other optional land uses. The
needs of crop production, recreation and other
benefits can be in conflict with the utilization of
a land application system for the treatment of
-------
LAND APPLICATION
wastewater. For instance, the planting, cultiva-
tion and harvesting of crops and the use of
recreation facilities may interfere with continu-
ous application of wastewater onto land areas.
The need for the system to either utilize all of the
flow or provide sufficient retention storage for
needed periods of non-operation must be pro-
vided. The objective of providing adequate treat-
ment of the effluent can not be sacrificed for
other needs and uses of the land; proper hand-
ling of the wastewater must be the first priority.
14. Choice of ground cover can play an important
role in the success of a land application system.
On other than sandy soil, it appears that forested
or minimally wooded or cultivated areas will ac-
cept greater rates of application of effluent with-
out ponding than will cultivated agricultural
areas. Many existing facilities utilize forest areas
and grassed areas for application. Forested areas
appear particularly useful for winter applica-
tions when fixed spray systems are used. Reed
Canary grass appears to be particularly well
suited for producing mulched ground cover
which can enhance soil assimilation and absorp-
tion characteristics.
15. Land application facilities that have been used
for many years are available for the study of
long-term effects of such use. They offer the op-
portunity to study effects on soils and ground-
waters. Thus, it appears unnecessary to support
separate demonstration facilities in each of sev-
eral states and regions. During the course of the
study project, several small-scale research and
demonstration projects involving land applica-
tion were disclosed. Some of these projects ap-
peared to have been instituted simply for the
purpose of convincing local and state officials of
the safety of this alternative method of treatment
and disposal. Specific evaluation at established
systems in the various climatic zones would ap-
pear to be more fruitful than new research in-
stallations for determining long-term effects
upon soil, vegetation, groundwater, and the in-
digenous ecology, or on the health of site work-
ers and adjacent residents.
16. Observations in the field and the survey of land
application systems which handle municipal
wastewater flows and industry-owned systems
which handle process waters did not reveal the
existence of specific health hazards and disclosed
very little concern over threats to the health of
on-site workers, residents of neighboring areas,
domestic animals or wildlife, or of those who con-
sume or come in contact with land-applied waste-
waters. The mail survey of other representative
municipal and industrial land application sys-
tems similarly provided no evidence of any
health problems associated with this method of
utilization.
Some concern over potential health hazards was.
however, expressed or inferred by officials of some
state agencies, who supplied information about their
policies on land application of effluents as an alter-
native means of wastewater management. Whether
this concern was based on specific information or
mere suspicions, founded or unfounded, could not be
determined from their response.
Inquiries have been made with inconclusive results
about the health implications of land application sys-
tems by several Federal state and local agencies, and
by other quasi-governmental and public service or-
ganizations. Concern over "the unknown" was ex-
pressed for such factors as potential viral and patho-
genic hazards resulting from dissemination of aerosol
sprays or mists and contacts with sanitary and indus-
trial sludge residues.
While the study did not disclose the cause for such
concerns, the bibliographic abstracts' prepared as
an integral part of this investigative project do in-
clude references describing possible health hazards
which warrant further study and these potential prob-
lem areas should certainly not be ignored.
A balanced consideration of the concerns, and of
the absence of any study evidence to support these
questions, would be of great value at this time.
RECOMMENDATIONS
I. Guidelines for land application of waste waters
should be prepared by the U.S. Environmental Protec-
tion Agency to provide full consideration of the wide
choices of available methods and procedures. Guide-
lines should be prepared in a manner which will not
restrict unduly the ability of local officials to make
full use of this alternative method of treating and
managing wastewater.
2. Land application must not be considered as a
panacea or universal method of treatment. Suitability
of each land application system can only be deter-
mined as a result of an interdisciplinary study for the
particular site. Soils, climate, degree of pretreatment,
groundwater conditions and availability of suitable
land acreages are important considerations
3. Preparation of a suitable public at ion to inform
the public about the practice of sewage effluent on
land should be sponsored by the United Stales En-
vironmental Protection Agency. Public relations
problems are usually encountered by agencies at-
tempting to implement any large public wastewater
* The bibliography for the APWA report is being published separ-
ately, entitled, IMIK! Application of Semitic Effluent', and Slittlf!e\
Selected Ah^tnu Is
-------
24
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
project. Recent efforts to consider land application as
an alternative in planning for regional approaches to
wastewater management have highlighted the need
for such publication.
4. Training opportunities should he provided to
hnni; to the attention of all disciplines involved in the
consideration and evaluation of a land application
facility rlie technical information which is available.
Widespread consideration and utilization of land ap-
plication cannot be made until such time as adequate
information concerning the technique involved is
made available. The experience gained by those who
have successfully utilized this wastewater manage-
ment method should be publicized.
5. Ciuidelines for the increased use of land applica-
ti<»i methods, which could result from the implementa-
tion of Section 201 of the 1972 Amendments to the
I cdcnil Water Pollution Control Law and its emphasis
on alternate wastes management techniques and sys-
tems, should clarify the question of whether health
hazards are a factor in the use of this system of treat-
ment and disposal. Definitive findings are essential to
the acceptance of land application systems, or to
their adoption for municipal or industrial effluent
management. Such findings should be provided with
promptness and clarity, either through evaluation of
existing data or any additional necessary research.
Without such positive information, published guide-
lines might either be inadequate or tend to be too re-
strictive. If they arc too stringent, this could endanger
the proper utilization of land application systems as
effective and economical solutions to water pollution
control problems and the rational use of wastewater
for crop and groundwater enhancement and other en-
vironmental-ecological benefits.
-------
Some Experiences
In Land Acquisition
for a Land
Disposal System
for Sewage Effluent
JOHN C. POSTLEWAIT
Muskegon County Department
of Public Works
HARRY J. KNUDSEN
Muskegon County Corporate Counsel
ABSTRACT
The paper attempts to deal with some of the ex-
periences in implementing the Muskegon County
Wastewater Management System in the areas of land
acquisition and relocation. No effort is made to in-
clude any other facets such as the technology involved
and costs. We have set forth some of the considera-
tions which must be addressed in early planning in
connection with putting together large tracts of land
including legal phases and the political acceptance.
This paper describes many of the problems which
may be encountered in any location in the country
where land must be acquired for the ultimate disposal
of waste, both liquid and solid. In addition, we have
tried to set out the advantages which can be derived
from the well planned multiple usage that such a site is
capable of providing. These include possible power
generation, either nuclear or fossil fueled stations, the
incentives for industrial expansion in the proximity,
improved wildlife population, recreational potential as
well as the agricultural advantages that are to be at-
tained through the exploitation of a "resource out of
place."
In summary, we have repeatedly advised the
necessity for a well planned public relations program,
initiated at the earliest possible moment, to provide in-
formation to the community and its leaders as well as
for the people who will be subjected directly to the ac-
quisition and relocation programs.
INTRODUCTION
This paper describes the experiences of the
County of Muskegon in establishing a sewerage sys-
tem to serve a metropolitan area composed of seven
cities and seven urbanized townships. It covers the
social, political, economic, and miscellaneous
problems encountered by the County Board of Com-
missioners in establishing the System with emphasis
on the problems relating to land acquisition and re-
location of individuals, families, farms and businesses
in a site area covering over 10,000 acres for the
disposal site.
The writers recognized that many of the problems
encountered by the County may not be applicable to
other municipalities which consider utilizing the land
disposal concept. However, the writers can best speak
from their own experiences and it is hoped that some
of the problems encountered and the solutions may
be helpful to other municipalities in avoiding some of
the difficulties encountered by Muskegon County.
One last comment before beginning our discussion:
Although the readers will note that many diverse
problems were encountered by the County, they were
all solved, and the system is now in operation.
Muskegon County had never been previously noted
for any peculiar abilities in problem-solving by
municipal cooperation. Bluntly speaking, the
political fragmentation of a County of less than
160,000 persons in sixteen townships, seven cities, and
25
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26
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
two villages, coupled with multiple other overlapping
municipal-type units, such as school districts and the
like, made many problems inevitable and unavoid-
able.
This paper deals with the problems encountered by
the County of Muskegon in establishing the land ac-
quisition phase of the System. Other problems which
confronted the County were of course, numerous, but
arc outside the scope of this paper. Rather then
dealing w ith the constraints topically, we feel this dis-
cussion will be more meaningful and understandable
by discussing the problems in sequence. Thus, we will
begin with the initial planning stage, implementation
planning, initiation of action and execution of the
plan through construction.
The project was partially funded by the Environ-
mental Protection Agency, with a 55 percent con-
struction grant and the State of Michigan Water Re-
sources Commission with an additional 25 percent.
The remaining 20 percent of the eligible construction
exists were provided by a local bond issue.
The project has also been awarded one of the
largest single Research and Development grants in
the EPA's and its predecessor's history.
Description of the Muskegon
Land Disposal System
Uur discussion can best be followed after a brief
description of the Muskegon Wastewater
Management System which recycles municipal ef-
fluent on the land.
The System is designed to serve 14 municipalities
or, as they are termed by the County Department of
Public Works, contractees. These 14 consist of seven
townships and seven cities. Six of the cities have ex-
tensive existing collection systems, while the remain-
ing city and the townships that do not have existing
facilities are now in varying stages of engineering
design. The county system provides access points at
\\hich each of the contracting units may introduce
their respective flows into the collection portion of
the county system.
In reality, there are two complete sub-systems that
make up the plan. In the north part of the county, a
facility is constructed to serve the cities of Whitehall
and Montague and the Township of Whitehall
(Figure 1) while in the lower part of Muskegon
County a vastly larger system serves the cities of
North Muskegon, Muskegon, Muskegon Heights,
Roosevelt Park, and Norton Shores, along with the
Townships of Muskegon, Laketon, Dalton, Egelston,
Moorland, and Fruitport (Figure 2).
After the wastewater is collected from the con-
tracting municipalities and delivered to a central
main pumping station, it is transported through ap-
proximately 12 miles of 66-inch concrete force main
to the aerated treatment lagoons, and after this con-
ventional treatment, is passed to storage lagoons.
These storage lagoons are sized to provide a
minimum of five month's wintertime storage capacity
for the design flow of 36 to 40 mgd. During the irriga-
tion season, the treated wastewater will be drawn off,
chlorinated, and pumped to 57 individual center-
pivot irrigation machines, most having a radius of
1300 feet, for land application.
The machines, or rigs, are basically designed as
those used in agricultural irrigation and are modified
to provide low-pressure, downward-directed spray.
The irrigated area is sized according 10 the estimated
nutrient content of the wastewater an J the ability of
the crops and soil to provide the necessary uptake
and reduction. The maximum application rate is set
at four inches per week, including rainfall. Normal
operation will more likely be about two inches per
week.
Total area under the rigs is almost 6,000 acres,
which will be farmed with forage-type grasses and
corn to start. The monies derived from this extensive
farming operation will be used to offset the operation
and maintenance costs. It is generally felt that this
system provides the opportunity to hold or reduce the
total cost while providing an effluent of a quality
superior to that obtainable by any other treatment
system and will also convert or recycle a great
amount of the waste nutrients through the crop
production.
After passage through a minimum of five feet of
this sandy soil, the water is collected by an under-
drain system, consisting of small-diameter, perforated
plastic pipe covered with a close mesh nylon sleeve to
prevent sand clogging. These underdrains are at
roughly 500 feet centers and lead to larger concrete
main drain lines. The collected underdrain water is
then conducted to the main outfall ditches where, af-
ter careful quality monitoring, it is discharged to the
natural waterways. It is anticipated that this water
quality will meet or exceed the Public Health
minimums established for drinking water.
Initial Planning
Any municipality which contemplates utilizing the
land disposal technique for sewage effluent must
develop careful and thorough plans for land acquisi-
tion with heavy emphasis upon public relations. Plan-
ning is, of course, essential in any municipal project,
but the land disposal concept demands especially
careful advance planning, because of the lack of
general understanding.
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LAND ACQUISITION
27
If we were requested to single out the main lesson
to be learned from the Muskegon project, without
hesitation, we would cite the problems of developing
sound public relations. Although the system was
based upon several widely used processes, they had
not been previously integrated for the system of waste
disposal on the scale involved in the Muskegon
system. The general public, therefore, had the idea
that the project was new, and its components were
untested and untried. While the wastewater manage-
ment industry readily recognizes that land disposal is
not new, we found the general public to be suspicious
and extremely credulous of the system and the
imagined danger to their health, safety, and welfare.
Some examples will later be cited to illustrate these
public doubts. Although we will discuss these experi-
ences later in this treatise, we wish to underscore the
critical importance of public support and under-
standing. These will be largely self-evident as we
discuss our experiences.
The selection of a proposed site for land disposal is
the obvious first step and the various technical con-
siderations which are involved are outside the scope
of this paper. The municipalities' engineers will have
to make studies and gather data on the potential sites
for the land disposal area. The determinations made
by the planners and engineers will involve the top-
ographic features, soil composition, drainage, and the
like.
The technological attractiveness of a given area
cannot, however, be given primary consideration for
many reasons, since site selection cannot be deter-
mined in the laboratory or on the planner's table.
Present land use is of critical import in the selection
process, since public acceptance and cooperation
will be substantially enhanced by selecting a site
which is not being ideally utilized. Public under-
standing is achieved somewhat more easily when land
reclamation can be claimed as a benefit to the
sewerage disposal system.
Figure 1 Sub-System in the North Part of the County, Constructed to Serve the Cities of Whitehall and Montague and the Township of
Whitehall.
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28
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
LlMl TO
SITE etouMDAftr
CMLOM.INAT'
f««l*ATIOM
-N-
TA MIC 4
STATIC*/
Figure 2 Sub-System in the Lower Part of Muskegon County, a Vastly Larger System Serves the Cities of North Muskegon, Muskcgon,
Muskegon Heights, Roosevelt Park, and Norton Shores, Along with the Townships of Muskegon, Laketon, Dalton, Egelston, Moorland, and
Fruttport.
Another prime factor to be considered in site selec-
tion is economics. Marginal land areas usually are
spai sely settled, and thus in addition to the lower cost
of lands, there are fewer families, farms, and business
to be relocated. All of these matters obviously must
be considered in establishing the economics of a land
disposal system in a given area. It is also important to
consider such costs in comparing the costs of a land
disposal system with the conventional primary,
secondary, advanced, and tertiary treatment systems.
Other important factors in site selection involve
both legal and political constraints. It is, therefore,
necessary that legal counsel be engaged early in the
proceedings to research the various legal problems
which may be encountered in any given site.
Problems such as municipal consent to allow the
location of a sewage disposal facility within its ter-
ritorial jurisdiction are a major obstacle where the
facility is to be located in an area outside the
municipalities which it is to serve.
In the Muskegon experience, we were faced with an
express statutory prohibition against locating any
treatment or disposal facility within any municipality
without a written consent from such municipality.
(Act 185 of P.A. of M.S.A. 5.570 (10); 1948 C.L.
123.740). Since the area to be served included the
major metropolitan areas, a consent in the form of a
contract, was necessary to permit the location of the
facilities in the rural areas. Fortunately, the township
boards of the three townships did adopt resolutions
and contracts permitting use of sites in their area.
In Michigan, the affairs of a township are governed
by boards of trustees of either five or seven members
who are elected to office. Since they must face future
elections, they are obviously sensitive to the wills of
their constituents. Thus, careful and thorough public
relations are essential.
-------
LAND ACQUISITION
Politicians in our area had a clear demonstration
of the effects of an aroused public, since the Town-
ship Supervisor (the Chief Executive Officer) of one
of the more populous townships was recalled from of-
fice, because he led the township board into granting
such a consent. Petitions were circulated to force an
election, and he was recalled from office by a wide
margin of votes. The central issue precipitating his
recall was his leadership in approving the township's
participation in the System.
Another legal and political problem we encoun-
tered which may be applicable in other areas, in-
volves the legal ability to acquire publicly-owned
lands under the power of eminent domain.
Specifically, in Michigan, a county has no authority
to condemn property owned by a constituent
municipality for a public improvement. This legal
disability is very serious and may prove to be more
serious than the municipal consent problem outlined
above. Michigan retains the last vestiges of a pure
democracy. Its elected township board does not have
the power to sell or convey real property without a
vote of the electors. Thus, even if the township's
board of trustees has the political courage to adopt a
resolution of consent to the location of a facility
within its boundaries, the electors may be able to
deny consent to sell or convey the lands. Since they
cannot be acquired under the power of eminent
domain, the property cannot be acquired without
either obtaining such voter authorization or a
statutory amendment granting such powers to a
municipality. Electoral consents obviously involve
public acceptance and understanding and again point
to the need for sound public relations. The legislative
process to obtain legal authority for one municipality
and even the state itself, to condemn publicly owned
lands, is lengthy and precarious. In Michigan, the
State Highway Department has often been stymied in
attempts to acquire such lands for roadways. Its at-
tempts to obtain legislative relief have not been suc-
cessful, which shows the rather dim prospect in
removing this legal deficiency.
It is critically important, therefore, to have a
thorough search as to the legal title to the property
which must be acquired for the disposal site. This
must be accomplished before the final site is select-
ed and the actual site engineering begins.
In the Muskegon project, we found that all three of
the townships where the sites were to be located, did
own a substantial amount of property. In addition,
two of the school districts had acquired lands for
various purposes. The same legal disability was ap-
plicable to the schools. To compound the problem,
we found that some of the lands were owned by both
the state and federal governments. There was no
likelihood that a county would be able to condemn
such lands.
It is, thus, imperative to research the title to the
disposal site area in order to discover these legal de-
ficiencies as soon as possible. The consent to such ac-
quisitions by local, state, and federal officials can be
a long and expensive process, so a very careful assess-
ment of the likelihood of obtaining such approvals
should be made as soon as reasonably possible.
Lest the readers be discouraged by the above legal
deficiencies, we hasten to point out that Muskegon
County was able to obtain such consents to the sale of
the lands from the municipalities, schools, state, and
federal governments. The techniques used to obtain
such approvals were varied and will not be here
discussed because of space limitations. The township
electors did consent, however, in spite of the poor job
of public relations for the entire project. These are
discussed later in this paper. In spite of the poor at-
mosphere in which these consents had to be presen-
ted, electoral approval was given.
There are a number of other legal and political
problems involved in any project which required the
acquisition of about IO,(XX) acres ot land. Zoning m;iy
present legal problems in certain states and areas. If it
is a problem, public hearings may be necessary in or-
der to change the zone. Legal issues on the authority
of a municipality to zone against a public improve-
ment must be carefully researched.
If roads are to be closed in the site area, the legal
and political problems involved must be thoroughly
investigated. Public hearings are often required in
such closure proceedings, but they may also be
avoided by certain techniques in each state. We over-
came the problems in Muskegon without public hear-
ings, but if such public hearings are required in other
states, it is obvious that good public relations are
essential.
A practical consideration which may involve both
legal and political judgements is the proximity ot
schools, churches, cemctarics, and even Indian burial
grounds. Hvcn though one may be able to condemn
school buildings or churches, the political ad-
visability of instituting such an action is worthy of
careful consideration. Anyone who has been involved
in attempting to relocate a cemetary or an Indian
burial ground can relate the emotional problems
which result. A public hearing is inevitable in such
matters whether or not the law requires such a pro-
ceeding.
In the Muskegon project, two cemetaries were ex-
cluded from the site area. Fortunately, they were on
-------
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
the perimeter of the main site, so it was easily han-
dled. The problems of encountering Indian burial
grounds in a site area may appear minimal, but we
can testify that even the possibility of disturbing
suspected Indian mounds, presents very real and
serious problems. In the instant project, someone
claimed that there were Indian mounds in a part of
the site area. As soon as that was announced, even
though there was little foundation for such
suspicions, we were visited by local tribes and the
State Commission on Indian Affairs. Fortunately, this
area was again on the perimeter of the site, so an
engineering change was effected to eliminate the area,
and thus, the area was excluded. Later, thorough in-
vestigation revealed that there were no Indian burial
grounds in the excluded area, but the question had
become moot by the time the determination had been
made. Suffice it to say that if the area had been cri-
tically needed for the project, construction would
have been delayed and considerable additional ex-
pense would have been involved until it was deter-
mined.
We, therefore, recommend any future planners to
research the disposal area to ascertain whether there
are any national monuments or other historical
memorabilia within the proposed site.
If there are public utility easements in the area,
serious legal and economic problems may be encoun-
tered if such facilities must be relocated. Fortunately,
the Muskegon engineers were able to locate the
facility so that relocating was confined to two high-
pressure gas lines and some power lines.
We also encountered a number of private ease-
ments for local industries which were no longer used.
The existence of such easements could also present
other legal and economic implications. These ease-
ments can all be disclosed by an early title search.
Another problem that may present difficulty is that
of oil. gas, and mineral rights. In the Muskegon
disposal area, many of the property owners had
executed leases of the fluid mineral rights. Some of
such rights were reserved in old conveyances, and the
State owned some of these rights. Thus, we were
presented with the problem of valuing such rights
and, indeed, determining whether the County could
legally force the condemnation of such leases and
rights under the power of eminent domain.
All of the above considerations are important in
the selection of the proposed site.
If one can contain the site within one municipality,
the problems of dealing with multiple municipalities
can be reduced. The necessary consents to location
and authority to sell lands are more easily handled
when dealing with just one municipality. Substantial
savings in time can also be effected.
After considering these legal and political con-
straints, a review of these problems and their
prospect for favorable resolution must be assessed.
The public relations agency should be involved in the
above process as well as the engineer, planners, legal
consultants, and other technical personnel.
Time may also be of the essence, so consideration
must be given to the statutes which grant authority to
acquire lands under the power of eminent domain. In
Michigan, we found that the law was deficient in
granting authority to obtain legal title and possession
prior to establishing the amount of just compensation.
We found that the state and county highway depart-
ments could take advantage of "quick-take" provi-
sions whereby the condemning authority could file
suit to condemn and post the amount of estimated
compensation with the Court and title and possession
of the property would vest in the County, unless the
property owner contested the issues of necessity.
Timing is always important for any project, and the
large land areas needed for land disposal are cer-
tainly not an exception. The absence of the "quick-
take" provision for a public health project was
deemed serious. The County, therefore, mobilized all
available forces to persuade our local legislators to
introduce such legislation to empower the county or
any other municipality to enjoy the same advantage
of the early possession of the property. After a her-
culean effort, the County was able to get an amend-
ment adopted to a state law to enable the County to
avail itself of this remedy. The legislation was not
adopted without a serious and time-consuming
struggle which overcame active opposition to the
amendment.
If the condemning authority is unable to procure
title and possession of the land prior to the long
delays inherent in court condemnation actions, this
can have serious economic implications, since no ac-
cess can be had for construction purposes.
Michigan, like most, if not all, other states, has a
condemnation law which permits a property owner to
contest the necessity of the project as well as the issue
of the necessity of his parcel for the project. If he
contests either issue of necessity, the municipality is
not materially helped by the "quick-take" provisions
of the law. The property owner must be accorded
these rights for constitutional reasons. Thus, an
assessment must be made as to whether there will be
an undue number of contests on the issue of necessity
and whether the timing and priority site area are
critical in the ultimate site selection process.
Fortunately for the Muskegon project, we only en-
countered one contest as to necessity out of the 415
parcels to be acquired, so that was not a serious
-------
LAND ACQUISITION
31
problem. That issue was later confined to the oil, gas,
and mineral rights, and that was then easily resolved.
We will report on our land acquisition later in this
paper.
Another area of legislative authorization should
also be explored in considering the problems of land
acquisition. The ability of the municipality to comply
with the Federal Uniform Land Acquisition and Re-
location Act of 1970, is very important in the acquisi-
tion process.
This statute had only recently been adopted by the
U.S. Congress and became effective on January 1 of
1971, just as the County was about to begin its land
acquisition. Since the Muskegon project was federally
funded, compliance with the law was deemed essen-
tial. Although the County did not have to comply
with all of the provisions of that Act until July 1,
1972, if it could obtain the legal authority to do so
before that date, its costs of relocation were 100 per-
cent funded by the federal government. Thus, a
strong incentive was presented to the various states to
adopt such legislation to extend relocation benefits to
the displaced persons, farms, and businesses.
The County recognized that the extensive benefits
which could be accorded to the persons, farms, and
businesses which were to be displaced would be of
benefit in obtaining the necessary property. These
"additive payments" substantially assisted the County
in acquiring the lands, since these payments were in
addition to the compensation for the land and prop-
erty taken. The relocation procedures and benefits
are described later in this treatise.
We can make this unequivocal statement. Without
the ability to make these additive payments, the
County would not have been able to obtain the
necessary properties in the short time allotted to such
acquisition.
The average family received an average additional
$4,500, plus moving expenses of $300, in addition to
being paid the fair price of the land. This "additive
payment", thus, enabled the displaced person to pur-
chase a decent, safe, and sanitary comparable
dwelling.
Other legal, political, and practical considerations
which are involved in land disposal include the
ultimate disposition of cleared material, such as tim-
ber, brush, stumps, logs, and general debris. The cost
ol disposing of such materials can be substantial.
With today's heavy interest in ecology, some
resistance may be expected if burning is to be used
for disposing of the combustibles for reasons of
economy.
In the instant project, we encountered resistance
from some environmental groups, as well as our own
County Health Department on the open burning of
the unsalvagable trees and stumps. We were,
however, able to resolve these problems by
negotiating acceptable guidelines to govern such
burning.
Post-Site Selection Planning
After the site has been selected and the public
relations program is in the process of development
and refinement, the municipality must adopt and
establish its policies and procedures pertaining to the
actual land acquisition. An acquisition plan should
be developed early in the proceedings, well in ad-
vance of the actual site selection. Thus, experienced
legal counsel should be selected to assist in devel-
oping the plan and advising the body as to all ap-
plicable laws, rules, and regulations. The assistance
of a real estate broker who is knowledgable and ex-
perienced in large land acquisitions is essential.
While a plan of procedure can be devised by the
broker and attorney, the plan must be presented to
the legislative or administrative body for review, re-
vision, and approval. Such a review involves a myriad
of policy and practical decisions which must be
made:
1. Selection of a competent land acquisition co-or-
dinator who can establish a land-classifications
system, acquisition map, and generally coordinate
the activities. A progress chart must be developed
to keep track of each parcel.
2. Determine whether title insurance should be uti-
lized, rather than obtaining abstracts of title with
attorney's title opinions. Select the title company
or attorneys. (In Muskegon, we used the insurance
system, since it was more expeditious and inexpen-
sive.)
3. Obtain Title Searches for the reasons hereinbe-
fore cited.
4. Select appraisers and the manner of such selec-
tion.
Since a large number of parcels may be in-
volved, it is well to consider the retention of an ap-
praiser with a staff sufficient to perform the task
within the time limits.
More than one appraiser may be needed for the
lands, especially if the parcel has substantial value.
Specialized appraisers or experts may be needed
to appraise timer, Christmas trees, oil, gas, and
mineral deposits, etc.
Problems are encountered in permitting an ap-
praiser access to the site. The federal law requires
the condemnor to permit the property owner to ac-
company the appraiser when he examines the
property. This is a very cumbersome, costly, and
impractical requirement, since the property
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32
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
owner often is hard to contact, breaks appoint-
ments, and the like. They often cause the ap-
praiser to spend unnecessary time to listen to
many irrelevant facts and circumstances.
Some persons deny access under any circumstan-
ces, so this presents problems as to appraisals
which need to be resolved. Public relations is es-
sential here. Absentee ownership is also a problem.
So are loose dogs who are unfriendly to strangers.
5. Determine whether the land will be acquired by
employees of the municipality or by an outside
firm.
How are they to be selected - qualifications, etc.
If an outside firm, is selection by bid or negotia-
tion.
(•>. Determine the method of compensation for land
acquisition agents.
Muskegon County elected to use outside firms to
handle the acquisition, and we would do so again.
All interested real estate brokers were invited to
submit bids and specifications were drawn.)
The County also agreed to pay a substantial
bonus if 75 percent of the parcels were acquired
within seven months. This incentive was very help-
ful in speeding the acquisition. A report on this will
follow.
7. Establish an acquisition schedule and priority
parcels. This is essential to meet construction
schedules.
8. Determine how relocation is to be handled, i.e.,
in-house or by an outside firm. Select the method.
Our County also used an outside firm to perform
this task, rather than attempting to train and super-
vise its own employees. There are many reasons to
prefer an outside firm because of County labor
contracts. We would use an outside consultant
again, it the need arises.
9 Select one or more attorneys to handle the con-
demnation trial work. Here is an opportunity to re-
tain the best and most experienced counsel in the
area before they are hired by the property owners.
10. Determine how the real estate closings will be
handled. We recommend the use of a title insur-
ance company and the same one as issued the pre-
liminary title commitments. The property owners
\vill trust the company to handle the deal as an im-
partial agent.
It also helps the municipality, since the title
company is then responsible for seeing that all in-
struments are recorded to comply with the condi-
tions outlined in the preliminary title commitment.
We had them make the computations of the pro-
rata taxes, etc. and the County thus issued just one
check. The title company made all of the disburse-
ments to pay back taxes, assessments, mortgages,
and the like.
Acquisition Plan
After the above ten major determinations have
been made, the municipality must establish the proce-
dures and policies for acquisitions.
Muskegon County used the following basic plan:
1. Appraisals were ordered.
2. Appraisals were reviewed by the Board of Pub-
lic Works after preliminary review by the director,
general acquisition attorney, and the acquisition
broker.
3. Appraisal amount was then either approved or
sent back for review by the Board.
4. After Board approval, a purchase agreement
was signed by the County and delivered to the
broker.
5. This purchase agreement was then presented to
the property owner by the broker, together with a
copy of the appraisal report. (This complied with
the Federal requirement on acquisition.)
6. The broker then attempted to explain the pro-
posal and appraisal.
7. If the price was not acceptable, the broker re-
ceived the criticisms and relayed them back to the
appraiser, if he thought they had merit.
8. The broker then negotiated a price, if possible. If
the demanded price was within reason, the broker
had the owners sign an option which could be pre-
sented to the D.P.W. Board.
9. If the deal was accepted by both sides, the mat-
ter would be turned over to the title company to
close the deal.
10. If a mutually acceptable deal was not made, the
Board would adopt a resolution authorizing con-
demnation proceedings to be instituted.
The preceding ten items are only a brief outline of
the basic land acquisition procedure and should not
be construed as an exclusive list or the only policies
and procedures involved.
Relocation
At the same time as the land acquisition proce-
dures are in process, a plan as to relocation has to be
developed, since acquisition and relocation are di-
rectly related to one another.
It is well, however, to select a different firm to han-
dle relocation than the acquisition broker's firm.
While the two sums are considered together, it is far
better to have each initially considered on its own
peculiar criteria.
After the firm is selected, the following general
plan and procedures were followed:
1. An immediate survey and census of the potential
displaced persons must be conducted.
This is critical, since once a project is under way
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LAND ACQUISITION
and the extensive benefits become known, the num-
ber of families appears to increase by magic. In
Muskegon, we thought we had 160 families in-
volved, and one way or another, it increased to
200. We found there were all sorts of oral life
leases (legal in Michigan) which required us to re-
locate tenants and roomers.
2. A series of public meetings to explain the bene-
fits should occur after the thorough census is made
for obvious reasons.
3. The relocation agency then begins gathering the
necessary information and attempts to locate com-
parable housing which will fill the needs of the re-
locatee and qualify as decent, safe, and sanitary.
We insisted on having the building inspector
examine every house into which a family intended
to relocate. This helped establish that the place
met codes and was decent, safe, and sanitary under
the regulations finally promulgated by the EPA.
We paid the fee for this inspection, as well as for a
termite inspection. These proved to be very wise,
since we ran into several problems.
4. After the comparable dwelling was selected, the
amount of the proposed additive payment was de-
termined and presented to the Board of Public
Works for review.
5. If the Board approved, the displaced persons
were informed of the action. If not, it was sent back
for further review.
6. If the relocatee was not satisfied, an appeal pro-
cedure was established, so the appellant could be
heard.
(Note: Items 4, 5, and 6 are extremely time-con-
suming, since there are many issues to resolve. It
takes a Board which is willing to devote many long
hours to careful review, in order to be fair to the
property owner, as well as the general taxpayers.)
7. After final determination, the relocatee would
be paid his additive payments which were required
to be invested in the actual new dwelling.
Care had to be taken, in order to ensure that no
frauds were perpetrated on the County and EPA.
There are a myriad of problems in administering
such a program. Another whole paper could be
devoted to that subject.
8. The moving expenses are also determined and
allowed on a schedule, rather than actual esti-
mates. If a relocatee wishes, however, he can have
his actual costs paid, but they rarely exceed the al-
lowable estimates, so the relocatee moves himself
and pockets the money.
9. A time is also established for the actual move
and to vacate the premises. This must be closely
coordinated with the priority schedule for land, the
availability of the new housing, etc.
10. As an absolute last resort, forcible eviction
may be necessary. We were fortunate, however, in
that we were not forced to evict anyone. Only one
action was commenced, and that was occasioned
because the tenants were in a divorce action which
complicated matters for us. They both left without
any fuss after the Court entered a judgment in
favor of the County. A neighboring community was
not so fortunate, since they had to bodily carry out
some elderly owners, all of which did not present a
good public image.
As stated earlier, acquistion and relocation must go
hand-in-hand in order to obtain title and possession
of the lands expeditiously.
Water Sampling
The County deemed it both prudent and desirable
to conduct thorough tests of the water quality of the
private wells located within one-hall mile of the out-
er perimeter of the site. These were conducted well in
advance of commencing the operation of the System,
so if a problem later developes with respect to their
well-water, the County will have the samples for base
data and comparison purposes.
The State of Michigan Department of Natural Re-
sources and the State Health Department were also
concerned that the present groundwater table under
and surrounding the site will not become contami-
nated by admission of any of the effluent. In order to
provide information on the present quality of the
groundwater supplies in the area, the sampling and
analysis program was carried out by obtaining sam-
ples of all the working wells in the areas immediately
adjacent to the land disposal area. This monitoring
program also provides the necessary data to prove
that no contaminants are leaving the site through
mixing into the groundwater table.
Miscellaneous Problems
In setting up the specifications for land clearing, it
was decided to give all acquired buildings to the con-
tractor for demolition. During the development of the
relocation plan it was determined by the Department
of Public Works Board that a few (about 25) of the
dwelling units were of sufficient quality to permit the
former owners to buy back for remodeling and mov-
ing to another site. If the former owner did not desire
to move and remodel these homes, they were adver-
tised and bids taken from the general public for their
salvage or removal.
One problem that became apparent from almost
the first acquisition, was that of vandalism and pilfer-
ing. It seemed that as soon as a party moved, the area
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
"jungle telegraph" would alert those in the habit of
making "moonlight requisitions" to become active.
Every effort by the county sheriff and other local
Authority proved of little or no value. This vandalism
and thievery continued throughout the acquisition
and relocation phases.
Another relocation problem was what to do with
the party who could not obtain financing at a reason-
able rate to provide for the relocatee to move into de-
cent, safe, sanitary housing. In this area, the County
Hoard decided to act as the mortgagor and provide
these people with direct financing, as provided for in
the Uniform Relocation Act. Fortunately, we were
only faced with three cases of this type.
Two complaints were filed against the County un-
der the State Civil Rights Law. We were charged with
discrimination because of race, color, and national
origin by one black lady and a Mexican family. These
complaints were withdrawn or dismissed after investi-
gation proved them to be without merit.
We feel the complaints were filed to put pressure
on the County to give the complainants more favor-
able treatment.
Many other problems were encountered which are
too numerous to mention here, but they were rela-
tively minor and were resolved without the necessity
for planning in anticipation of the problem.
Public Relations
All through this paper reference is made to ade-
quate planning, not only for the technical phases of
the project, but for all important land acquisition and
relocation phases as well.
In the initial budgeting there must be sufficient
funds established to provide for informing the local
political structures and those people directly in-
volved in the proposed land disposal area of the proj-
ect in all its phases from the very inception of the
plan.
In looking back on the Muskegon project, with the
advantage of 20-20 hindsight, we can see where a
public relations firm or consultant should have been
in on the ground floor to deal with the problem of
getting the information on the entire project before
the people, industry, and the politicians involved.
The public relations team should have a hand in
the ear 1\ planning of the land acquisition and reloca-
tion policies and procedures. They should also have
the responsibility for the conduct of public informa-
tional meetings to be held throughout the project
area, as well as the more common use of the media.
In addition to the regular public relation channels,
there must be support gained from the State levels,
such as the Legislators and Health Department offi-
cials. In Muskegon, a task group of community and
industrial leaders proved to be invaluable in this
area, as well as gaining community support, but
would have been of greater value had they had the
professional guidance of public relations expertise
early in the project planning, especially in working
with well-meaning environmental groups.
The question of removing public land from the tax
roles was well-handled in the Muskegon project. It
was a policy adopted in the early stages that a pay-
ment in lieu of taxes, based on a base-year valuation,
would be made to the governmental unit within
whose jurisdiction such land became county pro-
perty. This payment would then continue to be borne
by the system as an annual operation cost. This was
of substantial help in overcoming the opposition of
the townships and school districts of a substantial
portion of their property tax base.
Experiences in Execution of the
Acquisition and Relocation Plans
Acquisition
Some of the experiences in the Muskegon project
may be helpful in relieving the apprehensions which
have been raised in our earlier discussions of the
problems we encountered.
The County Board of Public Works engaged a pri-
vate real estate firm to perform the acquisition task.
Their contract provided for a base fee of $80,000 and
a $20,000 bonus if at least 75 percent of the parcels
were acquired in a seven-month period. The firm had
a substantial staff and was able to qualify for the
bonus.
The firm was authorized to begin making contacts
with the property owners on September 1, 1971, and
had acquired 85 percent of the parcels by May 1,
1972, just eight months later. They gave special atten-
tion to the priority parcels as directed by the County
pursuant to the engineer's and contractor's schedules.
Only 38 parcels could not be acquired through the
negotiation process, and thus, had to be assigned for
condemnation. Several parcels had one owner, so
only sixteen suits were filed and several of those set-
tled before trial. As of July 1, 1973, only eight suits
are pending trial.
The County used the quick-take provisions on the
38 parcels, so it was able to obtain title and posses-
sion of the lands in sufficient time so construction
was not delayed.
The County was able to acquire complete control
of all necessary properties within one year of the time
the parcels were assigned to the real estate brokers
for acquisition.
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LAND ACQUISITION
The appraiser, of course, was engaged early in the
proceedings and made a preliminary appraisal of the
probable land costs prior to the sale of bonds and re-
ceipt of construction bids. This should have been
done, however, in the site selection phase of the pro-
ject.
The land costs, including administration, totaled
$5,000,000 or $500 per acre. The legal and adminis-
trative costs were quite low, less than $400,000. These
included the appraisal fees, land acquisition real
estate agents' fees, title insurance, legal fees, closing
costs, and other administrative costs.
The actual land costs were somewhat higher than
the preliminary appraisal figure, but were considered
reasonable.
The County was very well-satisfied with the per-
formance of its real estate acquisition firm and the
other aspects of acquisition. The board was especially
pleased with its ability to acquire nearly all of the
parcels (92 percent without legal action). Over 80
percent of the parcels were acquired within five per-
cent of the appraisal amount established by its ap-
praiser. As we previously pointed out, the relocation
benefits had a substantial effect upon this accom-
plishment.
Acquisition must also be very closely administered
and coordinated with construction schedules for the
project.
We were also fortunate in that there was only one
contest as to necessity.
While there were substantial doubts as to the proj-
ect harbored by the residents in and around the site
area, some of the unrest was settled by a suit the
County instituted tor a Declaratory Judgment against
the opponents of the project. The trial of this case
and the unanimous favorable decision of a three-
judge panel of circuit judges had a quieting influence
on the whole community. The decision also dis-
couraged the property owners from attempting to
contest the issue as to necessity, and thus, made the
quick-take remedies meaningful.
Relocation
We have previously cited the great and helpful ef-
fect of the Federal Uniform Land Acquisition and
Relocation Act of 1970 upon the land acquisition
phase of the project.
Approximately 200 families were displaced, in-
cluding four farms and also one business. The bene-
fits paid out to the displaced persons totaled about
$1,000,000, and the cost of administration for the re-
location program totaled about $300,000.
The average per family additive benefit was $4,500
and a dislocation allowance of $200 and about $300
in moving expenses, for a total .of about $5,000 per
family on an average. A few persons received the
maximum of $15,000 for additive payments while
others received very small payments in addition to
the land values.
If the Muskegon experience is at all typical, any
land-use system which requires the relocation of
property owners from the proposed site will meet
with resistance from many of those persons who are
to be moved. This is a definite social problem that
must be considered in planning. Furthermore,
whenever a substantial number of voters are
unhappy, political repercussions, at least at the local
level, are bound to occur. The Muskegon project
necessitated the relocation of approximately 200
families to make available the 10,000 acres for the
project site. Almost from the inception of public
disclosure as to the location of the project, hostility
from the residents of the area displayed itself in
several ways.
Almost immediately, signs went up around the area
designating the site as "Sewer City". And, of course,
the local paper ran a lively column in, "As The Pub-
lic Sees It".
In spite of the heat generated, however, most politi-
cians at all levels responsible to the constituency
were in favor of the program and actively supported
it. Without this support, the project would never have
gotten off the ground. It should be remembered, how-
ever, that there will be those politicians sitting in the
weeds hoping to make political hay if the project
fails. These politicians, in the Muskegon experience,
were too few in number to scuttle the project. How-
ever, they provided a ready ear to disgruntled rclo-
catees, if not active encouragement Therefore, it
must be apparent that before serious consideration of
a land-use system, great effort must be expended to
inform and educate politicians, hopefully to obtain
their active support.
Of course, the people to be relocated cannot be
ignored. They must be fairly treated in every respect,
even when they are unreasonable in demands. Hardly
anyone is happy to see the government step in and re-
move them from their property, especially if it has
been theirs for many years.
The Muskegon project site is located in what was a
rural, sparsely populated, farming area. In setting up
the relocation phase of our project, we ran into a wall
of distrust. We even encountered the situation where
persons from outside the project area, in fact from
another county, would attend public meetings and
openly accuse us of being "Communist land-grab-
bers" intending to use the project to line our own
pockets. Hand-in-hand with their distrust was the fear
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
of unfair economic advantage.
In this latter respect, shines one bright light. In
January of 1971, the new Federal Relocation Law
went into effect. This law provided certain financial
assistance to those relocated as a result of a program
wherein any Federal funds are involved. In propor-
tion to. the federal government's share of project
costs, the federal government supplied matching
funds, along with local funds to provide relocation
benefits to those to be moved.
Basically, the benefits include moving expenses
and also what are termed "differential payments".
Differential payments are payments to make up the
difference between the amount paid for a person's
home and the amount necessary to purchase that per-
son a comparable, decent, safe, and sanitary replace-
ment home. There are other benefits available to ten-
ants, businesses, and farm operations.
Although this law will increase, substantially in
some cases, total project costs; many human prob-
lems are more adequately cared for. One of the great
injustices of the use of the condemnation power has
been in economics, wherein those forced from their
property can find replacement housing only at a
price higher than received for their own property
from the condemning authority. And, furthermore, in
many instances the situation arose where those forced
to move simply replaced themselves in ghetto type
housing unfit for human habitation.
Muskegon was the first major EPA sponsored proj-
ect to be affected by this law. We found that because
people could look to the relocation benefits to fill out
the economic package offered, very few cases went to
the courts for condemnation.
However, this can be a two-edged sword. In some
instances we found that employees of the agency re-
sponsible for buying the land were promising greater
benefits than could be supplied under the relocation
law. Of course, this led in some instances to cries of
betrayal and unfair dealing.
The problem of alleged broken promises reared its
hoary head in several situations. We found that cer-
tain of the relocation agents themselves either pro-
mised too much or what they did say was miscon-
strued by the individual relocatee. Many times relo-
catees would attend appeal sessions before the Board
of Public Works to argue "But this isn't what Mr.
promised." Or "Mrs - said that I would
receive $X dollars, instead of the amount awarded by
the board."
These communication problems were probably the
largest problem we had after it was clear in the peo-
ple's minds that indeed the project was going to be a
reality.
Therefore, along with education of local politi-
cians, extensive efforts should be made to inform the'
people of both the purpose and effect of the project
itself and also the benefits to be made available to
them.
We held public meetings, passed out pamphlets,
and prepared* newspaper explanations. But all of
these efforts will be unavailing if your own people are
not qualified or are improperly trained for the job.
The staff personnel must deal with the people to be
relocated on a daily basis. This means that if they are
properly trained as to the benefits available, and if
they are chosen for their ability to deal with people,
many of the problems earlier discussed may be eased.
Of course, each project will face its own peculiar
problems. The Muskegon project involved an innova-
tive system that went through a court test. Therefore,
many people resisted, feeling that the project would
fail. Furthermore, Muskegon was the first major test
of the newly-enacted relocation law. We decided to
utilize it, yet in several areas we did not know how to
apply it, since no guidelines had been promulgated by
EPA due to the recent passage of the Act. This led to
misunderstandings on the part of staff people which
was all too often passed on to the people in the proj-
ect area. And, of course, few projects will be as large
as the Muskegon project.
Many problems, however, will be similar, requiring
for planning purposes the suggestions we have out-
lined above.
In summary, the ability of the County to extend
these benefits made the acquisition far easier and
much more equitable to the displaced persons.
CONCLUSION
Although many problems are encountered in ac-
quiring large land areas for the recycling of sewage
effluent for large metropolitan areas, they can be re-
solved by careful planning and attention to public re-
lations.
We have outlined in this paper the need for close
cooperation between engineering and planning with
the persons who will be responsible for the land ac-
quisition phase of the project.
A competent public relations firm should be re-
tained as soon as possible, so proper community sup-
port can be supplied during the project. Most of the
opposition stems from lack of information and ignor-
ance rather than fundamental objections.
Competent and experienced technicians are, of
course, essential in the legal, appraisal, acquisition,
and relocation areas.
The Muskegon project will be very closely moni-
tored and scrutinized during its operations, and we
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LAND ACQUISITION
37
feel that many of the fears and concerns of the public
will be reduced or eliminated by our experiences.
The EPA research and development grants have pro-
vided the necessary funds for this demonstration.
We predict that after the Muskegon project proves
successful, there may be no need or requirement for
the municipality to own all of the lands used for land
disposal and no need to displace a large number of
families. We are confident that after the technologi-
cal data has all been gathered and evaluated by the
industry the effluent will be disposed on leased lands
and farms. It may even be sold to farmers for fer-
tilization purposes.
We also wish to emphasize that the capital costs,
operating costs, and problems in establishing a system
of recycling effluent should be compared with the
same costs attributable to the conventional advanced
treatment systems. Obviously, the comparative effec-
tiveness of treatment is of primary importance in the
consideration of treatment alternatives.
We also wish to point out that although a large
land area may be needed or required in land disposal,
planners must consider that the lands may be re-
claimed and the effluent utilized as fertilizer. In addi-
tion, the disposal area may be utilized for multiple
uses. A portion can be used for solid waste disposal,
electrical generating facilities, recreation, wildlife
sanctuaries, and many other opportunities which
have not yet emerged.
We conclude with a quotation from the federal En-
vironmental Protection Agency's 1971 Report on The
Cost of Clean Water (Volume II):
"The (land treatment procedures) have the great
virtue of recycling the materials so disposed, both by
replenishing water tables and by converting and uti-
lizing organic and inorganic waste matter in natural
life processes of decay and growth. Their secondary
merit is more germane to this discussion. Water
reaching watercourses after passage through the fil-
tering and decomposition processes afforded by soil
is far purer—provided that soil loading rates are not
exceeded—than any waste treatment process short of
distillation could make them."
DISCUSSION
QUESTION: J. Menzies, United States Department
of Agriculture. I would like to direct a question to
Mr. Postlewait concerning the remark he made about
the health authorities changing their mind on whether
the landowners would stay or not. I would like to ask
him the general question about what they found out
in Muskegon about the relationship between Federal,
State and local health authorities, and did they ever
get the lines of authority clearly figured out?
ANSWER: I think that would be a good topic for
another paper. I don't know whether the State and the
Federal people have gotten together under what ex-
tent myself. We have had several meetings in certain
areas that require exploration such as virology and so
forth, and I don't know just what the inner relation-
ship between the State and Federal are in some of
those areas.
QUESTION: J. Menzies, USDA. How about the
county?
ANSWER: The County Board of Health is gov-
erned by a board of county commissioners. The De-
partment of Public Works is governed by a board of
the county commissioners. Four of my seven board
members are on the County Health Board.
QUESTION: Belford L. Seabrook, EPA. Mister
Chairman (Darwin Wright, EPA), I would like to ask
you a question. The Office of Research and Monitor-
ing has a proposal from me for a research project.
Perhaps you could tell us something about the status
of that particular research project. Doctor Menzies is
aware of that.
DARWIN WRIGHT: Which one specifically are
you talking about?
QUESTION: Belford L. Seabrook, EPA. The one
that I proposed, the health effects of sewerages and
sludges.
ANSWER: Darwin Wright, EPA. We (EPA) have
not in the past placed a large emphasis from a fund-
ing viewpoint on the health aspects of municipal
wastewater treatment. We have recognized this prob-
lem and we are beginning in FY74 to work very
closely with the health effects and health research
people in EPA. We haven't defined all the activities
we are going to do in EPA during this next fiscal year
and in the following years, but I can assure you
Belford, that the health aspects are becoming more
important, both in terms of sludges and liquid ef-
fluents.
QUESTION: Parker Pratt, University of Califor-
nia. I would like to ask Mr. Postlewait if he would
elaborate on the objections of the Environmental
Protection Organization to his project. Give some of
the details of their objections.
ANSWER: Most of their objections, sir, were in
connection with the land itself. Now these weren't
really the people that lived on the land that we were
taking, the ones to be relocated. It seemed to be the
people in the immediate vicinity.
The land is an unproductive, sandy soil that had
been forested one time and then it turned into scrub,
very low yields agriculture. One of the statements
-------
38
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
that was attributed to the county administrator was
that a jack rabbit couldn't go across without packing
a lunch. But there was a very high water table, within
a foot or a foot and a half of the ground surface on a
good amount of the area, and the argument these peo-
ple had, was that we would be contaminating the
water table and the wells in the area. This was their
main concern. After we got into the land acquisition
phase, the active purchase of the land, and they lear-
ned of the money that was associated with the reloca-
tion program, a lot of these concerns seemed to
vanish in almost a direct proportion to the amount of
money that was paid for the land.
QUESTION: George Ward, Consulting Engineer,
Portland, Oregon. Would you elaborate more on
your nuclear plant considerations?
ANSWER: Rather than me fielding that question,
1 am going to turn that one over to Dr. Bauer.
ANSWER: William Bauer, Bauer Engineers,
Chicago. Some of the main considerations were thai
the site afforded isolation for the power plant. The
distance between the power plant site and the nearest
house was roughly two miles, so that there was con-
siderable isolation around it. And the second con-
sideration was that there was a water supply available
for make-up water for cooling. I think a third con-
sideration that was important was that there was a
main transmission line running right across the
property that connected the pump storage plant at
Ludington with Detroit and so if there were a power
plant sited at this location, it would be a very short
connection to the main transmission line.
Another consideration was the 1,700 acre cooling
surface that would be available if they subsequently
choose to use it. So far the negotiations provide that
they have free choice of this and they don't have to
use it. They might elect to use cooling towers instead,
and 1 think one of the reasons is that they are waiting
to see what the quality of the wastewater, treated
wastewater, in the lagoons is, before they make up
their minds on that. I have no doubt in my mind that
it is perfectly suitable water, because a much poorer
quality water is used almost every day in Chicago for
condensor cooling by taking the water out of the ship
canal, which many times during the year it is just
plain raw sewerage because of the overflows from the
combined sewers, and at all other times it is effluent
that is probably not quite as good as the one that will
be in the ponds at Muskegon.
The site also provided good foundations for a
power plant. It was drilled in order to see that there
would be no differential settlement problems. I think
it is a good site all the way around, and it wasn't just
fact that the isolation was provided, but it is a
strategic location from the point of view of the power
company.
QUESTION: Robert Schneider, Office ol Waicr
Resources Research, Washington, D. C. 1 have a
question to direct to Mr. Bauer in view of the fact he
seems to be answering some of the technical ques-
tions. Could you describe something about the
monitoring program for or on groundwater in the
area?
ANSWER: William Bauer, Bauer Engineers. The
main thrust in meeting the objection opposing pollu-
tion of groundwater, was to control the direction of
groundwater movement. This was one of the reasons
why the groundwater table being close to the surface
was actually an advantage by putting in an artificial
drainage system, one could depress the natural
groundwater level within the irrigation site and there-
fore make it a sink, so that the movement from the
surrounding area was towards the irrigation site and
not away from it. And, in a part of the site the drain-
age was done by wells because the natural water table
is deeper than can be economically reached with pipe
drainage and associated with all of this drainage sys-
tem are perimeter observation wells in pairs so that
one can determine that the direction of the ground-
water movement to make sure that it is always in to
the site and never away from the site, and the agree-
ment with the health authorities is that the wells will
be pumped to the extent necessary to maintain the
proper gradient. This means that they will be pumped
a varying amount depending upon the weather. Dur-
ing wet years the groundwater table will naturally
rise, during years it would fall, and so in order to ba-
lance the piezometric gradient properly, one would
pump less during wet weather, because you would
normally have lots of surcharge outside, and during
dry weather one would have to pump more and de-
press the groundwater level further in order to main-
tain that inward gradient.
The monitoring is systematic sampling of these
perimeter wells and they have been sampled for the
past six months. We have not yet started to irrigate.
The treatment system is such that it takes something
like ten months to fill up the lagoons, so the major
part of the irrigation will be next year, although there
will be some this fall.
-------
The Properties
of Sludges
R. B. DEAN
and
J. E. SMITH, JR.*
Environmental Protection Agency
Sludge is a liquid containing contaminants re-
moved from wastewater by physical, biological, and
chemical treatments. Although sludge contains solids,
the problem of its disposal is not primarily a solid
waste problem; it is rather the problem of disposing
of the water that is in close association with waste
solids. The major part of the cost of sludge treatment
and disposal is directly related to the tons of water
associated with each ton of solids. A typical digested
sludge contains about 20 tons of water for each ton of
solids. A thin, waste-activated sludge from biological
treatment may contain well over 100 tons of water
per ton of solids (Table 1). Dewatering and drying
sludge are expensive operations that can cost as much
is $50 per ton of dry solids produced.
TABLE 1
Water Content of Sludges
Treatment Percent Moisture
Primary Sedimentation
Chem. Precipitation
Trickling Filters
Humus - Low Rate
Humus - High Rate
Activated Sludge
Well Digested Sludge
Primary Treatment
Activated Sludge
95
93
93
97
98-99
85-90
90-94
Tons of Water/ Ton
Sludge Solids
19
13.3
13.3
32.4
- 65.6
- 70
-115
* Chief and Research Sanitary Engineer, respectively. Ultimate
Disposal Research Program, AWTRL, National Environmental Re-
search Center. EPA. Cincinnati. Ohio 45268.
The quantities of typical sludges as they are re-
moved from clarifier tanks or thickeners are shown in
Table 2. There are several types of sludge that may be
produced at different stages of a conventional waste
treatment system. Figure 1 shows a typical flow sheet
for an activated sludge plant. A trickling filter plant
would use essentially the same flow sheet, substituting
a rock or plastic-filled "filter" for the aerator. The
biological sludge sloughed off a trickling filter is fre-
quently called humus in England. It is similar but not
identical to the organic humus found in good soils.
Raw primary sludge consists of readily settleable
organic matter and fine silt. It is highly putrescible
and cannot be stored even for a few hours in warm
weather without some type of stabilization to prevent
odors from decomposition.
Waste-activated sludge (WAS) is the product of
biological multiplication of microorganisms feeding
on soluble and suspended organic matter in the pres-
ence of dissolved oxygen. A major part of the micro-
bial sludge is returned to the aerator; but a fraction,
representing net growth, is wasted. Waste-activated
sludge is also putrescible. It may be treated separate-
ly; it may be combined with primary sludge for fur-
ther treatment; or it may sometimes be discharged di-
rectly to the influent sewer to be collected with the
primary sludge.
Most of the bacteria in waste-activated sludge are
floe-forming Zooglea, which are related to Pseudo-
monads. Up to 90 percent of the Zoogleal mass is ex-
tracellular jelly secreted as bacterial capsules*. This
39
-------
40
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 2
Typical Quantities of Sludge Produced
In Wastewater Treatment Processes
Treatment
Plain Sedimentation
Tickling Filter Humus
('hem. Precipitation
Activated Sludge
Keefer
(19401
2,950
745
5. 1 20
19.400
Fair & Inihoft
r/965;
3,530
530
5,100
14,600
Rabbin
(1^3)
2,440
750
5.250
IK.7IX)
M
-------
PROPERTIES OF SLUDGES
41
Table 3
Properties of Digester
Supernatant (Municipal
Wastewater Sludge)
Item
Total susp.
solids (rng/1)
Total solids
(mg/1)
BOD (mg/1)
Volatile
solids (mg/1)
Alkalinity
(MOXrng/ I)
H2S(mg/l)
HN 3 -Nitrogen
(mg/1)
PH
Standard Rate
4,000-5,000
2,000-3,000
2,000-3,500
650-3,000
1,000-2,400
70-90
240-560
7.0-7.6
High Rate
10,000-14,000
4,000-6,000
6,000-9,000
2,400-3,800
1,900-2,700
190-440
560-620
6.4-7.2
After Maliva et al., 1971
TABLE 4
Bacteria In Sewage Sludge
(per 100ml)
Fecal oo/i
-------
42
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 5
Bacteriological Studies of Sludge
Produced in Plant-Scale Tests of Lime
Stabilization to pH 11.5
Bacterial Count (organisim/litcr of sl
Sli«li>t'
Alum- primary
Limed alum-primary
Ferric-primary
Salmonella
S/X't /c.\
IK)
None detected
> 24,
Linied ferric-primary None delected
PM'iultmonait
aeruii'moMi
1,300
None detected
610
None detected
Total Aerobic
Count » I0-i
41
S.O
190
029
TABLE 6
/. (/)
L-l
L-:
L-3
L-4
L-5
L-6
L-~
Temp
0" C
13.5<21
59-6413'
15
60-69
16 , ,
(M
63-66
15
67-75
30
68-73
18
77-85
14
87-91
I line Stilniiiiu'llii
(liotml ,\p
7.3
1 N.D.(41
2 N.D.
>23
1 ND.
9.3
1 N.D.
23
1 ND
2 N.D.
29
1 N.D
3
1 N.D
240
1 ND.
Pasteurization
l\eutloini>na\
aerutiinoM
20
N.D.
N.D.
>9.l
N D.
21
20
150
N.D.
N.D.
> 1100
ND.
7.3
N.D
43
N.D.
Test Results
Orntint.vm/100
'lulal ueroh'u
counts
2.5 x 10"
2 x 10"
1 x 105
3.4 x I08
7 x 10s
7 x 107
6.3 x 106
2.5 x 10s
6.4 x I06
1.3 x 10f
1 7 x I09
< 3 x 10*
1.2 x 10K
6 x 10s
1 x 10*
3 x 106
ml
/•<•<«/
< olilortn
6 x 10s
9000
B.D.L.
1.5 x I06
B.D.L
77 x I06
6000
2 x 10"
B.Dl,
BDL
99 x 106
5000
1.9 x l(f
B.D.L
1 x 10"
B.D.L.
/•<•< 240
1.5 >240
93
ND.
7.9 x 107
1.7 x 107
5 x 10s
5 x 107
1.7 x 105
4.2 x 104 10
Thrcxigh Copper
Tube with
3/ 16-inch
P-2
12
holes
25
70-83
59(7)
>240
1 N.D.
1.5 N.D.
N.D
16
N.D.
N.D
N.D.
1.8 x 108
4.4 x 105
4.5 x 10s
3.8 x 10s
8.4 x 106
B.D.L
B.D.L.
B.D.L.
2.1 x 105
BDL 58
B.D.L.
B.D.L.
Notes.
(1) L-number - Laboratory Tests
P-numbers — Large-Scale Tests
(2) Original Digested Sludge Temperature (typical)
(3) Pasteurization Temperatures (typical)
(4) N.D. - None Detected ( < 3/ 100 ml)
(5) Below detectable limits of analysis ( < IOOO/ 100 ml)
(6) Presence of Pwudomonas aeruftimna and relatively high fecal strep-
tococci suggests that heat did not penetrate the sludge.
(7) After cooling with air to 59" C
-------
PROPERTIES OF SLUDGES
raising the temperature to 70° C for one hour will de-
stroy pathogens, though coliform indicators may be
above 1000 counts per 100 ml. Warm sludge can be
applied to growing grasses if the temperature at the
soil surface does not exceed 60° C. Because evapora-
tive cooling of sprayed sludge can reduce t,le tem-
perature significantly, and heat may be lost in transit,
direct cooling may not be necessary in most cases.
Adverse effects are not expected if hot sludge is ap-
plied to bare soil before crops are started.
The cost of pasteurization was calculated by Trei-
bel in 1967 for German conditions. The heat for pas-
teurization was derived from the methane gas pro-
duced by the anaerobic digestion and heating costs
were not included. The cost of fuel to heat sludge
from 15° to 75° C was about $4 per ton of dry sludge.
Total costs for pasteurizing will decrease as the size
of the plant increases and can be expected to lie in
the range $0.25 to $1.00 per ton of liquid sludge. On a
solids' basis, a cost of $10 per ton is a fair preliminary
estimate.
Heat treatment of sludge to improve dewaterability
is carried out at temperatures above 160° C for about
half an hour. These conditions will completely de-
stroy all living organisms. If oxygen is present, some
organic matter may be oxidized. The process is then
called wet oxidation. All heat treatment processes in-
crease the concentration of soluble organic matter
and ammonia in the supernatant liquor or "soup."
This soup, although sterile when it is produced, is a
rich nutrient broth that can putrefy if it is allowed to
come into contact with bacteria that are in the air or
on container walls. The dewatered sludge is, how-
ever, resistant to putrefaction .
Lagoon or other storage for many months is fre-
quently depended upon to reduce the numbers of
pathogenic organisms, particularly those that cannot
multiply outside the human body1"1. Storage may be
necessary in any case if sludge is disposed of only
part of the year, and additional storage lagoons can
be built into the system to provide more protection
against transmission of disease. Sludge will settle in
lagoons to form a mud that may become too thick to
pump. Resuspension of the thick mud in water or ef-
fluent may have to be done before the sludge can be
removed from the lagoon.
Smaller plants traditionally dry digested sludge on
sand beds. Drying is facilitated by drainage of much
of the water through the sand to underdrains from
which it is returned to the plant2. Storage time of the
drying beds is usually several weeks to months and
provides time for a significant dieoff of pathogens.
Many small treatment plants make piles of dried
sludge available to anyone who cares to haul it away
for use in agriculture or gardening'. A few plants are
able to sell dry sludge for its organic nitrogen content
that is released slowly, making it desirable fertilizer
for lawns and golf greens.
Waste-activated sludge is dried in heated dryers
and sold by a few cities. Chicago used to sell for
$15/ton dried sludge that cost them $60 a ton to
"manufacture"". Milwaukee has developed a capable
sales organization that markets dried sludge under the
name "Milorganite"11. Some cities sell sludge to fer-
tilizer manufacturers who incorporate it into special-
ty products and handle the marketing of the prod-
uct10. Sale of dried sludge never makes a profit but
it reduces the costs of disposal below the costs of
other methods such as incineration. High temperature
in the dryers destroys most of the bacteria, but the
dried sludge may putrefy if it is allowed to get wet in
thick layers on the ground.
Sludge contains the major plant nutrients nitrogen,
phosphorus, and potassium at levels that are about
one-fifth of those found in chemical fertilizers. Table
7 expresses average analyses as the elements and in
terms of more familiar units. The low analyses ac-
count for some of the difficulties in marketing dried
sludge as a fertilizer. To get comparable responses to
nutrients, about five times as much sludge as chemi-
cal fertilizer must be shipped, stored, and spread on
the fields. Distribution costs that are proportional to
weight are a large part of the total costs of fertilizer,
therefore, high analysis fertilizers have a substantial
cost advantage for commercial farming. The sludge
that is sold for agriculture and horticulture is bought
for its content of organic slow-release nitrogen and
other organic matter that improves the physical prop-
erties of the soil.
TABLE 7
Mineral Nutrients Percent
of Dry Sludge Solids
Total N
Organic N
P
K
K2O
3 5 - 6.4
20- 4.5
08-3.9
18-87
02-07
0 24 - 0 «4
After Peterson, J R , 1972
When the purpose of sludge spreading is to dispose
of sludge at the lowest cost, much higher rates of ap-
plication will be used. The limiting factor in many lo-
cations then appears to be nitrogen. Excess nitrogen
is converted to nitrates that percolate down and con-
taminate the groundwater11. Public Health Service
(PHS) and World Health Organization (WHO) drink-
ing water standards of 10 mg/ 1 of nitrate nitrogen are
-------
44
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
exceeded in many groundwater supplies where fertil-
izer has been improperly applied to the soil.
Excess phosphate is strongly bound to most soils
and significant levels of soluble phosphates are vir-
tually unknown in groundwater supplies. Potassium
salts from fertilizers have not caused significant pol-
lution of groundwater"".
Sludge contains almost all of the metal ions that
are discharged to sewers or extracted from plumbing.
Heavy metals occurring in quantities that are signi-
ficant to agriculture include zinc, copper, nickel,
cadmium, mercury, and lead. Zinc and copper are es-
sential micronutrients that are present in sludges at
concentrations in excess of those present in soils.
Analyses of sludges for metals show wide variations
between locations reflecting local conditions. The
statistical distribution of values tends to be log-nor-
mal with a few very high values that can ordinarily be
traced to specific industrial discharges (Figure 2).
Source control with limits on discharges of toxic sub-
stances is practiced by cities that use their sludge for
agricultural purposes, but even the tightest source
control is unlikely to reduce the metal content much
below the median value. Table 8 lists the geometric
mean values for metals in sludges based on a review
of about 100 literature references and 80 additional
samples recently collected from sewage treatment
plants in this country25. The standard deviations of
the logarithmic distribution are as great as 4- or 5-
fold, so the numbers should not be used to predict
permissible loadings in the absence of analyses on the
sludges in question. Arithmetic averages are domi-
nated by high values and are typically about twice
the median value.
TABLE 8
Metals In Sludge
1971-1973
0 50 1 00 I 50 1 00 I 50 J 00 J 50 4 00 4 50 5 00
I OG OF VALUES FOR ZN
ORIG IN Al V AlUL 5 IN PPM
Figure 2 Distribution of Zinc in Sewage Sludge.
Element
Cd
Cu
Hg
Ni
Ph
'in
Geomt'trtf
Mean
(ppm)
61
906
14 5
223
4()4
2420
Literature
Spread '
5.89
266
5.24
4.54
4.H
278
Atomic Absorption
deoinetnt
Menu
(ppm)
93
1840
32
733
2400
6380
* Spread isantilog of standard deviation of log-normal distribution.
The absolute quantity of metal added to the soil
may have little relation to the concentration that is
available to growing plants. Since organic matter in
sludge complexes heavy metals, a typical response
from adding sludge to a soil low in organic matter is
to reduce the availability of metals, even though the
sludge may contain more metals than the soil28. The
availability of a metal in a soil depends on many fac-
tors including pH, organic matter, other metals, and
the variety of the plant that is growing in the soil.
Studies of highly metal ized soils derived from mine
dumps have shown that certain varieties of common
plants have an inherent resistance to toxic metals that
takes the form of a cytological barrier to absorp-
tion27.
Lime inactivates most heavy metals by precipita-
tion, making them less available to growing plants.
Zinc toxicity from continued applications of sewage
sludge in Nottingham, England, was easily corrected
by treating the soil with agricultural lime29. Translo-
cation of metals into plant tissue varies greatly with
the element, plant species, pH, and other soil fac-
tors26. Much work remains to be done in the area of
metal transport from sludge-treated soils to plants,
but the long history of successful use of sludge as a
soil amendment in agriculture indicates that the
hazards are slight and probably are easily controlled
by appropriate farm practices.
REFERENCES
1. Adrian, D. D., and Smith, J. E., Jr. (1972). "De-
watering Physical-Chemical Sludges." Proc. Conf. on
Application of New Concepts of Physical-Chemical
Wastewater Treatment, Vanderbilt University, Sept.
18-22, 1972, Pergamon Press, Inc., 273-289.
2. Adrian, D. D. (1973). "Dewatering Sewage
Sludge on Sand Beds," Chemical Engineering Prog-
ress Symposium Series, 129, AIChE, "Water-
1972,"69, 188-191.
-------
PROPERTIES OF SLUDGES
45
3. Babbitt, H. E. (1953). "Sewerage and Sewage
Treatment," John Wiley and Sons, Inc., N.Y., 7th edi-
tion.
4. Brooks, R B. (1970). "Heat Treatment of Sew-
age Sludge," Water Pollution Control, 92-99 and 221-
231.
5. Compost Science, March-April 1970, "How Safe
is Sludge," pp. 10-12.
6. Dalton, F. E., Stein, J. E., and Lynam, B. T.
(1968). J. Water Poll. Control Fed. 40, 789.
7. Dotson, G. K., Dean, R. B., and Stern, G. (1973).
"Cost of Dewatering and Disposing of Sludge on the
Land," Chemical Engineering Progress Symposium
Series, 129, AIChE, "Water-1972," 69, 217-226.
8. Dugan, P. R., and Picrum, H. M. (1972). "Re-
moval of Mineral Ions from Water by Microbially
Produced Polymers," Proc. of the 27th Annual Pur-
due Ind. Waste Conf., May 2-4.
9. Fair, G. M., and Imhoff, K. (1965). "Sewage
Treatment," John Wiley and Sons, Inc., N.Y., 2nd
edition.
10. Farrell, J. B., Smith, J. E., Jr., Hathaway, S. W.,
and Dean, R. B. (1972). "Lime Stabilization of
Chemical-Primary Sludges at 1.15 mgd," Pres. 45th
Annual Conf. Water Poll. Control Fed., Atlanta,
Georgia, Oct. 8-13.
11. Frobisher, M. (1965). "Fundamentals of
Microbiology," W. B. Saunders Co., Philadelphia,
7th edition.
12. Green, J. E. (1972). "Sludge Oxidation," The
American City. Oct. 1972.
13. Hinesly, T. D., Braids, O. C, and Molina, J. E.
(1971). "Agricultural Benefits and Environmental
Changes Resulting from the Use of Digested Sewage
Sludge on Field Crops." An Interim Report on a
Solid Waste Demonstration Project, USEPA SW-30d.
14. Reefer, C. E. (1940). "Sewage Treatment
Works," McGraw Hill Book Co., Inc., N.Y.
15. Kenner, B. A., Dotson, G. K., and Smith, J. E.,
Jr. (1971). "Simultaneous Quantitation of Salmonella
Species and Pseudomonas Aeruginosa," USEPA, Na-
tional Environmental Research Center, Cincinnati,
Ohio.
16. Kenner, B. A. (1972), In-house Report,
USEPA, National Environmental Research Center,
Cincinnati, Ohio, March 31, 1972.
17. Kbser, A. (1967). "The Use of Sewage and Sew-
age Sludge in Agriculture from the Point of View of
Veterinary Hygiene," Schr. Reihe Kuratoriums Kul-
turbaiiw. No. 16, 25-42 (German).
18. Krige, P. R. (1964). "A Survey of the Pathogen-
ic Organisms and Helminthic Ova in Composts and
Sewage Sludge," J. Inst. Sew. Purif., 215-220.
19. Loehr, R. C. (1965). "Aerobic Digestion Fac-
tors Affecting Design," Water and Sewage Works,
Ref. No. 112, R169-R180.
20. Maliva, J. F., Jr., and DiFilippo. J. (1971)
"Treatment of Supernatants and Liquids Associated
with Sludge Treatment," Water and .S'cmr/yc Work\,
Ref. No. 118. p. R-30.
21. Mayrose, D. T., and Walsh, J J. (1971). "Heal
Conditioning ot Sewage Sludge—Dorr-Oliver's I-ar-
rar System," Pres. at New York Water Poll. Control
Assn. Meeting, Jan. 1973.
22. McCabe, J., and Eckenfelder, W. W. (1963).
"Advances in Biological Waste Treatment," Perga-
mon Press.
23. Parizek, R. R., Kardos, L. T., Sopper, W. E.,
Myers, E. A., Davis, D. E., Farrell, M. A., and Nes-
bitt, J. B. (1967). "The Pennsylvania State University
Studies No. 23—Waste Water Renovation and Con-
servation," The Pennsylvania State University, Uni-
versity Park, Pennsylvania.
24. Peterson, J. R., Lue-hing, C., and Zen/, D. R
(1972). "Chemical and Biological Quality of Munici-
pal Sludge," Symposium on Recycling Treated Muni-
cipal Waste Water and Sludge Through Forest and
Croplands, The Pennsylvania State University, Uni-
versity Park, Pennsylvania.
25. Salotto, B. V. (1973), USEPA Report, National
Environmental Research Center, Cincinnati, Ohio. In
preparation.
26. Schafer, K., and Kick, H. (1970). "The After-
Effect of the Treated Sludge of Waste Water Contain-
ing Heavy Metal in a Field Test," Land- Win Forsch
23 (2), 152-161.
27. Smith, R. A. H., and Bradshaw, A. D. (1972).
"Stabilization of Toxic Mine Wastes by the Use of
Tolerant Plant Populations," Inst. Mining Met.
Trans., Sect. A, 81 (Oct.), A230-A237 (England).
28. Stevenson, F. J. (1972). "Role and Function of
Humus in Soil with Emphasis on Adsorption of
Herbicides and Chelation of Micronutrients," Biosci-
ence 22(11), 643-650.
29. Stone, R. (1969). Personal Communication.
30. Styers, F. C. (1973). "Sludge Recycling—The
Winston-Salem Experience," Proc. of 1973 National
Symposium on Ultimate Disposal of Wastewatcrs and
Their Residuals, Durham, N.C., April 26.
31. Transactions of the 15th Annual Conf. on Sani-
tary Engineering (1965), University of Kansas Publ.,
Bull, of Engineering and Architecture No. 54.
32. Treibel, W. (1967). "Experiences with Sludge
Pasteurization at Niersverband; Techniques and Eco-
nomy," Intl. Research Group on Refuse Disposal
(IRGRD), Info. Bull. Nos. 21-31, Aug. 1964-Dec.
1967, 330-390.
33. Wilson, C. (1973). "Merchandising Heat-Dried
Sludge," Proc. of Symposium on Land Disposal of
Municipal Effluents and Sludges," Rutgers Univer-
sity, New Brunswick, N.J., March 12-13.
-------
46
RECYCLING MUNICIPAL SLUDGKS AND KFKI.UKNTS
DISCUSSION
QUESTION: John Walker, USDA, Beltsville. Just
a quick comment and followed with a little question
for Doctor Dean. On his liming sludge study, we were
interested in liming sludges as they might be useful in
agriculture and whether these high limed sludges
would have an adverse effect on plant growth, and we
are also interested in what would happen to the
disease organisms with time after the sludges have
been applied to soil. So we put some raw and digested
sludges into the soil surface and rototilled it in, plus
we put some in trenches in the soil and we studied the
pH in the microorganism level and plant growth with
time. We found after about a month the pH dropped.
We asked Blue Plains to lime the sludges and then
give them to use at pH's ranking from about eight to
eleven and a half. The upshot of the whole thing was
that in the beginning we had identical results to what
Dr. Dean showed, but after they were mixed with the
soil the pH levels dropped back down and instead of
not finding Salmonella we then found Salmonella or-
ganisms even at the highest lime level, both in tren-
ches and was mixed in the soil surface, so, my ques-
tion is have you other work that would either tend to
confirm or deny this type of finding, and would
higher pH initially kill them once and for all?
ANSWER: We have a contract now with Batelle
Northwest in Richland, Washington following the be-
havior of limed sludges. We don't have any results on
the re-growth of Salmonella, which is what this ap-
pears to be. I don't know from the Beltsville experi-
ence whether the Salmonella that was re-growing was
the same serological types or not. I suspect that the
Salmonella types that re-grow in the soil might not be
the same as those that are pathogenic. This is the sort
of thing that we find very frequently that was referred
to by the previous speaker. The natural coliform or-
ganisms in the soil, that have never been in a colon
are distinguishable from the fecal coliforms. We don't
have a full answer on that. We do know that a limed
sludge if stored for too long will putrify.
QUESTION: John Walker, USDA. The microor-
ganisms that came back were definitely fecal coliform
organisms. I am not sure about the serology of the
Salmonella. Do you know about that, Wiley?
ANSWER: Wiley Burge, USDA-ARS at Beltsville.
We did not look at the pseudotype. We plan to do
that.
QUESTION: Rufus L. Chancy, USDA. Mr. Sea-
brook mentioned earlier that there is a possibility that
metal levels in sludges is going to fall drastically if
ordinances promulgated under these current laws are
used to diminish industrial releasing metals to the
sewerage. I am wondering, have you predicted what
levels we are going to have in sludges ten years from
now. Let's say we have all these laws in effect by then
and in progress. What are we are going to have then
Dr. Dean and Mr. Seabrook and others?
ANSWER: Robert Dean, EPA. The reduction that
we can expect is down not much lower than the load
that we saw or the geometric mean. There is an in-
teresting paper from New York on a symposium held
last year on recycling of metals which is available
from EPA. They found that copper, about a third of
the copper in New York City's wastewater comes
from domestic plumbing. Not copper pipes but brass
fixtures rotting out. Likewise with the zinc. They
made a very good job of knocking out and getting af-
ter the people who dump plating wastes, and you
knock back quite away, but remember you yourself
are excreting zinc. Now, we are not going to be able
to go all the way back. We can get those that are up
four times what a reasonable average is, but we aren't
going to be able to get any substantial reduction in
something as ubiquitous as copper or zinc. On the
other hand I am very pleased to say that the battle
against PCB is succeeding. As you know there was
quite a flap about PCB's turning up and there is no
carbon paper. They were being made by National
Cash Register in Dayton, and their sludge was run-
ning around a hundred parts of PCB's when the
national average is around three parts. So, a year and
a half after the flap, we went back and they are way
down and the other plants that were high, probably
from recycled paper, are down into the normal level,
so we are making progress. But I don't think you can
do it on copper and zinc until you go to all plastic
plumbing.
COMMENT: A. Kaplovsky, Rutgers University.
As some of you gentlemen know, we are in a demon-
stration project which is funded by EPA and Ocean
County, New Jersey. We made a study of various
sludges in which we made certain there was ab-
solutely no industrial waste whatsoever, and we did it
on five separate digestive sludges and compared it
with a whole series of analyses that I had gathered
when I was Director of Research at the Chicago
Metropolitan Sanitary District. Unfortunately I can
only report that all metals that we examined, all
heavy metals, came out in the same order of
magnitude in domestic waste as the industrial waste
that we found in Chicago, concentrations were
unusually high and we are convinced that this is what
we have now as background. The zinc levels, the cop-
per, the lead, the cadmium and so on. The lead is
what surprised us very much. Someone suggested that
perhaps unleaded gasoline and it gets slushed into the
sewers as storm water and it gets into some of the
-------
PROPERTIES OF SLUDGES
47
sewerage plants, but the lead levels were at the same
order of magnitude. So, I don't think we have much
hope unless you have a gross industrial waste pro-
duct.
I might also add that my experience in Chicago was
that they had a predominance of the metal plating in-
dustry located in the Chicago metropolitan area, so
you are looking at a very high level compared to a
municipal system.
QUESTION: Darwin Wright, EPA. I would like to
ask Bill Rosenkranz to discuss something which the
crowd here may not be quite aware, and that is the
problem of heavy metals in urban run-off.
ANSWER: Bill Rosenkranz, EPA. I don't have
any numbers with me, but we have recently published
a report on urban storm waters that was done by
URS. The heavy metal problem is very distinctive
there as well as it is in other wastewaters. Lead con-
tents were very high and actually after the storm you
can measure the amount of lead discharged in a large
metropolitan drainage area in terms of tons. This
very clearly indicates that in any community where
you have storm waters entering your collection
system through a combined sewer or other means, the
possibility of having elevated levels of heavy metals
in sewerage and in the resultant sludges and effluent
are probably higher than they arc in other com-
munities. And we have some further work going on to
further define this in the Washington area being done
by Biospherics. While I haven't seen the data yet,
there was a news release that came from the contrac-
tor the other day, which indicated some of the same
things that I just mentioned. The heavy metals and
some of the other wastewater constituents in storm
waters is a very significant problem.
-------
Characteristics
of Municipal
Effluents
CHARLES E. POUND
and
RONALD W. CRITES
Metcalf & Eddy, Inc.
ABSTRACT
Physical, chemical, and biological characteristics of
municipal wastewaters are presented and discussed
with respect to land application. Both constituents of
raw wastewater as well as effluents from four types of
plants are included. These constituents are compared
to those of acceptable irrigation waters and to the rela-
tive amounts of each that would normally by applied
to the land. The objective of this comparison is to put
irrigation with municipal effluents into perspective.
On the basis of the data presented and the correspond-
ing literature review, several areas of research are out-
lined.
INTRODUCTION
Before the effects of effluents on the land can be
understood or evaluated, it is necessary to know the
characteristics of the waters being applied. Hence,
the objective of this paper is to summarize the char-
acteristics of municipal wastewater and the effluents
from various common treatment processes. Several
wastewater constituents will then be compared
quantitatively to those normally applied to farm
lands by irrigation and the addition of commercial
fertilizers. These comparisons are intended to put our
knowledge of effluent characteristics into perspec-
tive, as related to land application. From these com-
parisons and a review of the subject matter, conclu-
sions will be drawn regarding the areas when addi-
tional information and research is needed.
Data presented herein were collected from a vari-
ety of sources. In addition to a literature search and a
review of office files, much of the data was collected
during the performance of a "State-of-the-Art" study
presently being completed by the author for the
USEPA12.
Constituents of Wastewaters
The constituents of raw sewage and the subsequent
treatment plant effluents depend upon the character
of the municipal water supply, the industrial mix of
the community, the proportion of commercial to resi-
dential development, and the nature of the residential
community. Consequently no specific conclusions
can be drawn for a community by reference to gen-
eralized data. Only trends or generalities can be de-
veloped and discussed from such data. The wide vari-
ations that can be encountered from drainage areas
having selected land development characteristics and
yet having essentially the same water supply are illus-
trated in Table 1.
Municipal wastewater has been characterized as
weak, medium, or strong depending on the concentra-
tions of various constituents10. The range of values
for normally listed constituents is given in Table 2.
The characteristics of raw sewage are important if
screened and comminuted sewage is under considera-
tion for treatment by the overland flow or grass fil-
tration method. For most application approaches,
some form of pretreatment is practiced, consisting of
at least primary treatment and probably secondary
49
-------
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 1
Comparison of Sewage Characteristics from Areas of Selected
Types of Development
Constituent MD
Total solids.
mg/l 344
Suspended solids,
mg/l 120
Volatile solids.
nig/ 1 88
Settlcable solids.
mg/ 1 3 9
BOD. mg/ 1 89
COD, mg/ 1 260
Oil and grease,
mg/l 25
Coliforms,
MPN x 10V100 ml 84
Note: MD = medium density;
Source: Reference (9).
Residential areas
LD LD
474 701
117 283
81 182
2.3 10.9
61 129
205 422
18 29
79 52
LD= low density
LD
499
56
37
0 1
315
426
34
297
ureas
-------
CHARACTERISTICS OF EFFLUENTS
51
treatment. Effluent characteristics from several pri-
mary plants located in various communities in Cali-
fornia are given in Table 3. Except for alkalinity and
TDS values, the concentrations of various constitu-
ents do not seem to vary widely from plant to plant.
Secondary treatment has been loosely defined for
many years as either trickling filters, activated
sludge, or some type of pretreatment followed by oxi-
dation ponds. In order to compare the effluents from
each of these processes, data were collected from sev-
eral facilities for each process. Effluent characteris-
tics for trickling filter plants, activated sludge plants,
and oxidation ponds, are given in Tables 4, 5, and 6,
respectively. The plants listed in these tables are
mainly located in Southern California and in many
cases the drinking water supplies are relatively highly
mineralized. As a consequence the TDS and other
specific mineral concentrations in these wastewaters
are high. Average values of the constituents listed in
Tables 2 through 6 for the various types of plants are
presented in Table 7. As expected, the only constitu-
ents listed that are substantially lowered by secon-
dary treatment are BOD and total nitrogen.
TABLE 3
Municipal Effluent Characteristics
from Primary Treatment Plants
ing/l (except «.s noted)
Constituent
Arroyo
Grande"
Siintti
Harhara
Ventura
LRMUl).
Sp (list No I
Physical
Total suspended solids
Chemical
Specific conductivity,
mhos/cm
Total dissolved solids
pH. units
BOD
Total nitrogen
Nitrate-nitrogen
Ammonia-nitrogen
Total phosphorus
Chlorides
Sultate
Alkalinity (CaCo<)
Boron
Sodium
Potassium
Calcium
Magnesium
Sodium adsorption ratio
Biological
Coliforms,
MPN x I06/100 ml
102
2,300
1,344
--
123
.SI
0
41
12
528
70
1 ,040
0.60
330
13
11.9
3.4
6.8
2,850
1.898
77
110
21
0
16
14
657
222
735
0.95
460
24
134
42
89
-
1440
76
162
3S
0
25
10
395
298
__
1 0
320
18
102
46
6.6
-
935
68
216
41 7
1 4
1 1 6
75
264
133
131
209
33
31
14
7.8
6.1
dEffluent applied to the land.
Sources' Column 1-3 - Reference (6).
Column 4 - Reference (8)
-------
52
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 4
Municipal Effluent Characteristics from
Trickling Filter Treatment Plants
Mg/l (except as noted)
Constituent
Chemical
Specific conductivity.
fj.mhov' cm
Total dissolved solids
pH, units
BOD
Total nitrogen
Nitrate- nitrogen
Ammonia-nitrogen
Total phosphorus
Chlorides
Sulfate
Alkalinity (CaCOi)
Boron
Sodium
Potassium
Calcium
Magnesium
Sodium adsorption ratio
Carpenttria
Sun. Dist.
2,150
1,350
K.I
6
12.7
8.8
0.0
9.1
343
275
640
0.55
305
13
100
52
6.0
San Luis
Ohispo"
1,140
780
7.3
15
25.2
14.2
6.1
13.0
158
115
305
0.3
150
13
30
49
3.9
Ventura
(east Me)
1,500
7.5
10
II 2
0.0
8.4
13.0
352
600
-
1.5
370
17
120
61
6.8
Laniina Co.
San. Oi.il.
1,700
1 ,034
77
40
16.8
2.5
9.3
16.9
254
280
528
0.6
245
15
70
41
5.8
3Effluent applied to the land.
Source' Reference (6)
TABLES
Municipal Effluent Characteristics from
Activated Sludge Treatment Plant
mull (except as noted)
Constituent
Chemical
Total dissolved solids
pH, units
BOD
Total nitrogen
Nitrate-nitrogen
Ammonia-nitrogen
Total phosphorus
Chlorides
Sulfate
Alkalinity (CaCOO
Boron
Sodium
Potassium
Calcium
Magnesium
Sodium adsorption ratio
Abilene,
I exn\
750
7.1
17
12
0
12
9.4
168
--
1%
192
36
17
44
5.6
Conejo
Valley
San Dist.
California
1 ,080
7.2
40
33.4
0.0
30.0
13.4
167
330
0.8
260
17
40
33
7.4
Oak View
San. Dist..
California
1,235
7.6
18
21.3
3.6
16.0
16.0
299
256
-
-
215
15
110
47
4.3
Pomona,
California
605
7.7
6
28.0
12.0
13.0
--
107
86
--
0.7
101
13
42
26
3.0
Note. Effluent from each plant applied to the land.
Sources: Column I - Reference (12).
Column 2 - Reference (6).
-------
CHARACTERISTICS OF EFFLUENTS
53
TABLE 6
Municipal Effluent Characteristics from
Oxidation Pond Treatment
Constituent
Chemical
Specific conductivity,
fi mhos' cm
Total dissolved solids
pH, units
BOD
Total nitrogen
Nitrate-nitrogen
Ammonia-nitrogen
Total phosphorus
Chlorides
Sulfate
Alkalinity (CaCO3)
Boron
Sodium
Potassium
Calcium
Magnesium
Sodium adsorption
ratio
Montalvo
M.I.D.
-
1,775
7.6
65
22.5
0.0
18.0
9.4
239
560
-
1.2
335
15
122
72
5.9
Newberry
Park Academy"
1,460
1,012
8.3
71
15.3
2.7
9.5
4.2
146
110
1,084
0.7
267
13
47
31
7.4
Saticoy
San. Dist."
-
2,330
8.1
74
40.2
0.3
0.8
7.8
151
762
-
1.4
390
21
178
91
5.7
Bislwp"
340
204
7.0
-
15.0
0.0
7.4
5.5
19
10
280
.33
38
7
23
1
2.1
'Effluent applied to the land.
Source' Reference (6).
TABLE?
Average Effluent Characteristics from
Various Treatment Plants
m/t/l (except as noted)
Secondary
Constituent
Chemical
Specific conductivity.
fimhos/cm
Total dissolved solids
pH, units
BOD
Total nitrogen
Nitrate-nitrogen
Ammonia-nitrogen
Total phosphorus
Chlorides
Sulfate
Alkalinity (CaCO.i)
Boron
Sodium
Potassium
Calcium
Magnesium
Sodium adsorption
ratio
Primary
-
1,402
—
152
37
0.3
23
11
461
180
635
1.2
329
22
%
34
7.5
Trickling
filters
1,663
1,166
-
17
16
6.3
5.9
13
276
317
491
0.7
267
14
80
50
5.6
Activated
sludge
-
917
-
20
23
3.9
17
12.9
185
224
--
0.7
192
20
52
37
5.0
Ponds
--
1,330
—
70
23
0.7
8
6.7
138
360
682
1.2
257
14
92
48
5.2
Sources: Tables 3 through 6
-------
54
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
A limited amount of information on heavy metals
in the effluents described is available and is shown in
Table 8. None of the concentrations shown would
preclude the use of the effluent for irrigation of most
crops. The National Technical Advisory Committee
in their report on Water Quality Criteria lists trace
element limits for irrigation". Checking this list, it is
found that the only element approaching toxic levels
is copper at 0.1 mg/ 1. Each heavy metal listed except
iron, has a lower limit of tolerance for use in irriga-
tion water. This limit has been defined, however, for
only a few crops and a few soil types. Much more re-
search is needed in this area.
It should be noted that although heavy metals are
present in municipal effluents the amounts are gen-
erally quite small. For example, an activated sludge
effluent with a zinc concentration of 0.06 mg/ 1, irri-
gated at a rate of 8 ft/ yr would add only 1.3 lb/ acre
to the soil in a year. For some plants, an additional
fertilizing with zinc would be required for satisfac-
tory growth. For example, where zinc deficiencies are
found in plum and prune orchards, addition of from
10-15 lb/acre of zinc is recommended.
Characteristics of Wastewaters
The characteristics of wastewaters may be classi-
fied as physical, chemical, and biological. Each of
these categories are discussed in the following para-
graphs.
Physical Characteristics
The most important physical characteristic of
wastewater is its total solids content. The solids in-
clude floating, suspended, colloidal, and dissolved
matter.
The solids are important because they have a ten-
dency to clog the soil pores and coat the land surface.
Other physical characteristics are temperature, color,
and odor. Temperature is not a great problem be-
cause municipal wastewater effluent has a fairly even
temperature, 50" F to 70° F, which is not harmful to
soil or vegetation. It is beneficial in that in winter, it
has a thawing effect on frozen ground and may keep
soil bacteria alive. Effluent has been used to spray on
crops in freezing weather to form an insulating ice
coating which protects the crop from cold air''.
Color of effluent has little effect on the application
to the crops, but it can be used as an indicator of the
composition of the wastewater. Fresh sewage is usual-
ly grey; septic or stale sewage is black. The presence
of industrial wastes can give the sewage color from
chemical in the waste.
Odors in wastewater are caused by the anaerobic
decomposition of organic matter. Although hydrogen
sulfide is the most important gas formed from the
standpoint of odors, other volatile compounds such
as indol, skatol, and mercaptons also cause noxious
odors. These odors are then released to the at-
mosphere by spraying or aerating.
TABLE 8
Concentrations of Heavy Metals in
Wastewater Effluents
Type ol plunl
Constituents
UK/1 (pph)
Arsenic
Chromium
Copper
Lead
Manganese
Zinc
Iron
Primary
2
0
60
55
35
750
830
Trickling
Fitters
3
0
70
15
10
85
160
Adivali'il
\ludne
8
10
40
10
10
60
320
1',/nth
6
7
100
20
30
200
390
Note Data taken from at least 2 plants.
Source Reference (6)
-------
CHARACTERISTICS OF EFFLUENTS
55
Chemical Characteristics
The chemical properties of wastewater can be
divided into three categories: organic matter, inor-
ganic matter, and gases.
The organic matter in wastewater is in the dis-
solved form as well as settleable solid form, and it is
principally composed of proteins (40 to 60 percent),
carbohydrates (25 to 50 percent), and fats and oils
(10 percent). Other organic compounds, such as
phenols, surfactants, and agricultural pesticides, are
generally present in small quantities. Only when the
trace organics reach higher concentrations do they
become a problem. Ordinarily these substances are in
such a small quantity that they have no short term ef-
fect on the soil or vegetation; however, their effect on
groundwater quality is a point of concern. Long term
effects of trace organics have not been adequately de-
termined.
Many of the inorganic compounds provide nutri-
ents for the vegetation, but they also can be toxic to
plants at certain concentrations. Examples include
boron, lead, nickel, and zinc. The major plant nutri-
ents present in wastewater are nitrogen, phosphorus,
and potassium. The aggregate of dissolved com-
pounds is the TDS (total dissolved solids). The TDS
content, often measured as, electrical conductivity, is
generally more important than the concentration of a
specific ion such as chloride. TDS values above 750
mg/ 1 for irrigation waters will require leaching either
by adding excess irrigation water or from rainfall.
The relationship between the principal cations in
wastewater—calcium, magnesium, sodium, and po-
tassium—is of importance. When the ratio of sodium
to the other cations, especially calcium and magnes-
ium, becomes too high, the sodium tends to replace
the calcium and magnesium ions on clay particles.
The predominance of sodium ions on clay particles
has the effect of dispersing the soil particles and
decreasing the soil permeability. In most cases per-
meability of soil becomes a hazard before sodium af-
fects plant growth. In a few plants this is not strictly
true, notably avocados. To determine the sodium
hazard, the SAR (sodium adsorption ratio) was devel-
oped by the U.S. Department of Agriculture Salinity
Laboratory and is described in detail in Agricultural
Handbook No. 60'". It is defined as follows:
SAR=Na/[l/2 (Ca + Mg)]l/2
where Na, Ca, and Mg are concentrations of the re-
spective ions in milliequivalents per liter of water.
Because the presence of bicarbonates and carbon-
ates may result in precipitation of calcium carbonates
and thereby release more exchange sites on the soil
particles for sodium, an index was developed to serve
as a guide to evaluating this constituent of irrigation
waters. This index is termed the Residual Sodium
Carbonate or simply RSC". It can be calculated by
the following equation:
RSC = (CO; +HCO;) - (Ca*+Mg*)
where concentrations of all ions are in milliequiva-
lents per liter of water as is the RSC.
The quality parameters and their values that are
generally used to rank irrigation waters in terms of
potential hazard to soil and plants are listed in Table
9. It should be noted that these values were developed
for the western states where the annual rainfall is rel-
atively low and therefore natural leaching is low.
These values must be evaluated for the specific site
TABLE 9
Quality Classification of Irrigation Waters
Level i/l Hazard
Medium
^Hazardous for nearly all crops above 4.0 mg/1.
Source' Reference (17).
Virv Infill
Salinity
Electrical conductivity.
micromhos/cm
TDS, nig/I
Alkalinity and
permeability
SAR
RSC, mg/l
Toxins
Boron, mg/ 1
Chlorides, mg/ 1
< 750
< 500
< 3
< 0
< 0.5
< 70
750-1,500
500-1,000
3-5
0-1.25
0.5-1.0
70-140
1,500-3,000
1,000-2,000
5-8
1 25-2.50
1.0-2.0
140-280
> 3,000
> 2,000
> 8
> 2.50
> 2.0a
> 280
-------
56
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
and conditions under consideration. Using the classi-
fication levels shown, the effluent water quality for
Bishop (Table 6) would be rated as a "low hazard"
except for the RSC which would be a "high hazard".
Effluent wastewaters from most of the other plants
listed in Table 3 through 6 would be classified as
"medium to very high hazard", hence requiring spe-
cial water and soil management procedures.
CJases in wastcwater, other than those mentioned in
regard to odors, are relatively unimportant in land
application. Dissolved oxygen is usually depleted
soon after wastewater is applied to the land. Atmo-
spheric oxygen is relied upon for maintenance of
aerobic soil conditions.
Biological Characteristics
Wastewater is teeming with microorganisms that
are constantly changing its characteristics. The pre-
dominant microorganisms are bacteria.
Wasterwater may contain pathogenic organisms
which cause diseases, such as salmonella gastroenter-
itis, typhoid and paratyphoid fevers, bacillary and
ameobic dysentery, cholera, and infectious hepatitis7.
Prctreatment is required to remove the bulk of these
microorganisms from the wastewater. The presence
of enteric pathogens is often ascertained by testing
tor coliforms. £. coli (Esclierichia coli) are used as in-
dicator organisms because they are more numerous
and more easily tested for than pathogenic organisms.
Tests have also been developed to distinguish be-
tween total coliforms, fecal coliforms, and fecal
streptococci. These tests are important because many
common soil bacteria are measured in a total coli-
form count. It is therefore important that a more
specific test be used than the presumptive coliform
test for measuring the degree of wastewater renova-
tion for enteric bacteria in the soil system. The ele-
vated temperature, fecal coliform test may be used to
provide this differentiation".
Viruses are also present in sewage but in fewer
numbers than bacteria. They are excreted from the
intestine of man. particularly those infected with a
viral disease. Approximately 100 serotypes have been
isolated from the excreta of man and more will prob-
ably be found1. Because viruses are obligate parasites
and require a host in which to live, they are often
classified according to the host they infect.
Raw municipal sewage can be expected to contain
from 10*' to \Q* total coliforms and from 480 to 1,677
PFLJ/ L of enteric viruses2. Neither of the preceding
quantitative values are indicative of total bacterial or
total viral counts. The bacterial counts reflect only
those bacteria which have many of the same physio-
logic characteristics as enteric bacteria. The viral
counts reflect the limitations of today's techniques
and may be one or more orders of magnitude low.
Nonetheless they are relative and permit some
evaluation of the effectiveness of our treatment proc-
esses and disinfectants. The expected removals or de-
struction of bacteria and virus by various treatment
processes are listed in Table 10. As indicated virus
removals up to 99 percent have been reported. As
Sorber reports, however, there can remain about 50
virus particles per liter in chlorinated secondary ef-
fluent14.
TABLE 10
Removal or Destruction of Bacteria and
Virus by Different Treatment Processes
/*««-ss
Fine screens
Plain sedimentation
Chemical sedimentation
Trickling fillers
Activated sludge
C 'hlnnnation ol effluent
''''"<•"
liaclenu"
10-20
25-75
40-80
90-95
90-98
98-99 +-
/ removal
Vint*.
0-3h
96-97h
W- -K4h
O-88/99'l
99.1
''Source' Reference (10)
hSource. Reference (2)
c Source Reference (3)
d6.0 and 8.4 hours of aeration; respectively.
Effects of Pretreatment on
Wastewater Characteristics
Conventional wastewater treatment begins with
preliminary operations such as screening and sedi-
mentation. Effluent from these operations is referred
to as primary effluent. This primary effluent may be
further treated by biological oxidation or by physi-
cal-chemical processes. Effluent from the more wide-
spread biological processes, such as activated sludge,
trickling filters, or oxidation ponds, is referred to as
secondary effluent. Constituents removed by the vari-
ous operations and processes in conventional treat-
ment will be noted in the following discussion.
Primary Treatment
Coarse screens, present in nearly every treatment
plant, remove large floating objects and rags. Fine
screens are generally not used any more in sewage
treatment because the smaller solids are removed by
sedimentation and biological oxidation.
-------
CHARACTERISTICS OF EFFLUENTS
57
Sedimentation removes much (50 to 65 percent) of
the suspended solid matter in the wastewater. Grit
and gross settleable solids are often removed in grit
chambers prior to primary sedimentation. BOD is re-
duced by primary sedimentation approximately 25 to
40 percent10, and some organic nitrogen, phosphorus,
and heavy metals are also settled out.
Primary treatment has a limited effect on bio-
logical characteristics. Sedimentation will remove
most of the Ascaris eggs, but beef tapeworm eggs,
hookworm, amoeba cysts, Salmonella, and viruses
will not be completely removed". Most of the dis-
solved and colloidal matter present in wastewater
will not be removed in primary treatment.
Secondary Treatment
Biological oxidation results in the removal of col-
loidal and dissolved organics to a large extent. Addi-
tionally, some nitrogen and phosphorus are incor-
porated into bacterial cells and removed by secon-
dary sedimentation. Most dissolved inorganics are
not affected by secondary treatment. Secondary treat-
ment provides an additional removal of bacteria and
viruses by flocculation and secondary sedimentation.
Disinfection
Disinfection, the selective destruction of disease-
causing organisms, may be accomplished using heat,
ozone, bromine, iodine, or, most commonly, chlorine.
Adequate disinfection requires complete and rapid
mixing and minimum contact time. The presence of
suspended solids hinders the process of disinfection;
therefore, secondary effluent is more readily disinfec-
ted than primary effluent. The number of coliform
organisms can be reduced by disinfection techniques
from 106 organisms per 100 ml to less than 2.2 organ-
isms per 100 ml.
Comparing Effluent Irrigation
to Normal Irrigation
Stromberg'" estimated the gross balance of several
agricultural minerals added to the cultivated lands of
Fresno County, California. He concluded that there
was a deficiency of phosphorous and potassium being
applied to the soil, compared to the amount removed
from the field in the harvested product. Nitrogen, sul-
fur, chlorides, and sodium were being applied in ex-
cess of plant needs. Using data presented by Strom-
berg, together with Department of Water Resources
data for water quality \ Table 11 was constructed to
compare normal agricultural conditions in Fresno
County to a hypothetical application of secondary ef-
fluent. In all cases, the minerals would be applied at
heavier rates for effluents. This does not prove that
irrigation with secondary effluent is not feasible. It
only means that the effluent should be distributed
over more land and diluted by high quality waters,
TABLE 11
Hypothetical Comparison of Minerals Added by
Irrigation plus Fertilization Versus Minerals
Added by Effluent Irrigation
(.\ni\nnifnt
Nitrogen
Phosphorus
Potassium
Sodium
Calcium
Magnesium
Chloride
Sultate
Boron
TDS
1-if.li
HIK/I"
1 8
29
11.5
15.9
7.9
10.8
5.9
0.1
155
u'tilt'r
Ib/ttt ri'lyr*'
19
31
124
172
85
117
64
1.1
1,675
/•er/;//7m
tn itl
(itncthlnH'iits '
Ih/ucrc/vr
57
6
3
—
193
--
1.6
462
-
720
lolill
lh/
-------
58
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
receive additional treatment, or that provision must
he made for adequate soil and water management
practices when developing the program. The first al-
ternative is in fact proposed for effluents from both of
the cities of Fresno and Bakersfield, California.
A second hypothetical example was developed
using irrigation water from the Colorado River, such
as is used in Imperial County, California. Mineral ad-
ditions from this poorer quality Colorado River
water plus an allowance for fertilizer and soil amend-
ments compare more closely to secondary effluent.
Nevertheless, provision for good soil and water man-
agement practices would have to be provided for a
successful operation (Table 12).
Many examples of irrigation with municipal waste-
water attest to the fact that problems associated with
chemical buildup can be resolved or, in fact, do not
exist. However, as attempts are made to apply efflu-
ents to the land at higher and higher rates and under
various climatic conditions, more precise knowledge
must be available regarding the soil-water-plant sys-
tem. How far can the system be stressed before failure
occurs? What plants are available that can take up
large quantities of chemicals, heavy metals and water
without ill effects?
Areas of Suggested Research
Water will increase in TDS by 200 to 400 mg/ 1
for each pass through the municipal system of water
treatment, customer use, and wastewater treatment. It
will also pick up substantial numbers of enteric bac-
teria and viruses. Therefore we must be prepared to
accept this water and prepare it for ultimate absorp-
tion into groundwater bodies or surface water courses
or for direct recycle to agricultural and industrial
uses. As part of that preparation the following re-
search is suggested.
I. What plants are available that would:
a. Tolerate heavy amounts of water
b. Take up large amounts of nitrogen and other
nutrients
c. Tolerate or take up high quantities of heavy
metals.
A list of such plants and their limitations should
be available to those involved in planning and
operating effluent irrigation systems.
2. What quantities of chemicals will selected plants
take up under luxurious uptake conditions? How
does the uptake affect the quality or potential
uses of the plants?
TABLE 12
Hypothetical Comparison of Minerals Added by
Irrigation with Colorado River Water Plus
Fertilization versus Effluent Irrigation
( i nnlllltcnl
Nitrogen
Potassium
Sodium
Calcium
Magnesium
Chloride
Sulfate
Boron
TDS
/'re
mi,*//"
03
5.8
125
95
30
124
314
0.17
856
•\/i Wuler
Ih/Mif/vrl'
3
63
1,360
1,040
327
1,350
3,420
1.8
9,330
Fertilizer!:
i/nil
amendments
Ih/tiire/vr
57
3
--
193
1 6
462
—
717
Total
Ih/tu re/yr
76
66
1,360
1,233
327
1,352
3,720
1.8
10,047
Additions
trom
effluent'1
Ih/iicre/yr
378
289
2,240
932
577
2,380
1,920
16
1 3,450
"Source Reference (5)
hApplied at 4 tVyr
c Average county-wide values for Fresno County, California from Reference (16).
''Pomona. California wastewater from Reference (6) applied at 8 ft/yr.
-------
CHARACTERISTICS OF EFFLUENTS
3. Can soil amendments be added to offset the
buildup of various constituents of effluents? If
so, what kind and what are their limitations'?
4. What pretreatment methods are available for re-
moving those constituents that cannot be bal-
anced by luxurious plant uptake or by addition
of soil amendments? What are the economic
limitations of pretreatment methods?
5. What is the mechanism of virus inactivation and
how can this mechanism by applied to effluent
disinfection procedures?
6. What effect does high TDS effluent have on the
adsorption of viruses in soils? What is the sur-
vival time of these adsorbed viruses?
7. Can superior indicator organisms to E. Coli be
found in measure pathogen survival in soil?
8. What are the long effects of trace organics con-
tained in wastewater effluents that are applied to
the land?
CONCLUSION
In conclusion, decisions regarding the application
of effluents to the land cannot be made based on gen-
eralities but must be made based upon actual water
and soil quality data and environmental conditions
such as rainfall, evaporation rates, and ranges of tem-
peratures. Present knowledge is sufficient for estab-
lishing an effluent irrigation system in those cases
where quality fits within the normally accepted limits
for irrigation waters. However, in the remainder of
the cases additional research is needed to produce
tolerant plants and techniques necessary for complete
management of the system.
REFERENCES
1. Akin, E. W., Benton, W. H., and Hill, W. F. Jr.,
"Enteric Viruses in Ground and Surface Waters: A
Review of Their Occurrence and Survival," Proceed-
ings Thirteenth Water Quality Conference, University
of Illinois, pp 59-74 (February 1971).
2. Berg, G., "Removal of Viruses by Water and
Waste Treatment Processes," Proceedings Thirteenth
Water Quality Conference, University 'of Illinois, pp
126-136 (February 1971).
3. Burns, R. W., and Sproul, O. J.. "Virucidal Ef-
fects of Chlorine in Wastewater," Jour. WPCF, Vol.
39, No. 11, pp 1834-1849 (November 1967).
4. Department of Water Resources, "Fresno-Clovis
Metropolitan Area Water Quality Investigation,"
State of California, Bulletin No. 143-3 (April 1965).
5. Department of Water Resources, "Quality of
Surface Waters in California, 1962," State of Califor-
nia, Bulletin No. 65-62 (April 1965).
6. Department of Water Resources, "Report on
Quantity, Quality, and Use of Wastewater in South-
ern California July 1, 1964 - June 30, 1965," State of
California, Southern District (January 1967).
7. Dunlop, S. G., "Survival of Pathogens and Re-
lated Disease Hazards," Proceedings of the Sympo-
sium on Municipal Sewage Effluent for Irrigation,
Louisiana Polytechnic Institution (July 30, 1968).
8. East Bay Municipal Utility District, Special Dis-
trict No. I Annual Report 1968-1969, Oakland,
California.
9. Metcalf & Eddy, Inc., "Stormwater Problems
and Control in Sanitary Sewers - Oakland and Berke-
ley, California," Report for USEPA, p. 65 (March
1971).
10. Metcalf & Eddy, Inc., Wastewater Engineer-
ing, McGraw-Hill Book Co., New York, N.Y. (1972)
11. Parizck, R. R., et al., "Waste Water Renovation
and Conservation," Penn State Studies No. 23, Uni-
versity Park, Pennsylvania (1967).
12. Pound, C. E., and Crites, R. W., "Wastewater
Treatment and Reuse by Land Application," Office
of Research and Monitoring, EPA (July 1973).
13. Sepp, E., "The Use of Sewage for Irrigation—A
Literature Review," Bureau of Sanitary Engineering,
Calif. State Dept. of Public Health (1971).
14. Sorber, C. A., Schaub, S. A., and Outer, K. J.,
"Problem Definition Study: Evaluation of Health and
Hygiene Aspects of Land Disposal of Wastewater at
Military Installations," U.S. Army Medical Environ-
mental Engineering Research Unit, Report No. 73-
02, Edgewood Aresenal, Maryland (August 1972).
15. Standard Methods for the Examination of Water
and Wastewater, 13th ed., American Public Health
Association (1971).
16. Stromberg, L. K., "Fertilizer and Soil Amend-
ments as a Source of Farm Wastes," Proceeding',
Symposium on Agricultural Waste Waters, Davis,
California, pp 67-69 (April 6-8, 1966).
17. Strombery, L. K., "Water Quality for Irriga-
tion," University of California Agricultural Exten-
sion Service, Fresno, California (January 20, 1970).
18. U. S. Salinity Laboratory, Diagnosis and Im-
provement of Saline and Alkali Soils, Agriculture
Handbook No. 60, U.S. Dept. of Agriculture (1963).
19. Water Quality Criteria, Report of the National
Technical Advisory Committee, FWPCA (April 1,
1968).
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60
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
DISCUSSION
QUESTION: Tom Hinesly, Office of the Under-
secretary of the Army. I would like to ask Mr. Pound
if he can give us an example of where sewerage ef-
fluent has been used for irrigation and where we have
had an example of a toxic condition being developed
from heavy metals.
ANSWER: I don't know of any site where heavy
metals has been in a toxic situation. I think the main
problem in this whole subject, and the reason I
brought it up is because people talk of it so much. The
main problem that you Find in the literature, of
course, is the deficiency of heavy metal in soils, not
excess of heavy metal.
QUESTION: William Bauer, Bauer Engineers,
Chicago, Illinois. You mentioned the need to identify
plants that would be able to take up increasing quan-
tities of heavy metals. Have you given thought to sim-
ply the matter of accumulation of heavy metals in
soils and banking them in effect over long priods of
time.
ANSWER: Of course this happens. There is no
question about it. I will have to back up on what I
said earlier, because I did read, but cannot remember
the reference, that somebody found that there was a
metal toxicity. They then resolved the question sim-
ply by additional application of water and flushing
the water, flushing the accumulation of either salt or
heavy metals or both, down into the soil, away from
the root zone. The common way that we eliminate the
accumulation of salts and heavy metals in any irriga-
tion system is by the flushing action of the water as it
carries it down and so some excess irrigation is re-
quired. The normal practice of irrigation in Califor-
nia in the early part of the year, is to pre-irrigate sub-
stantially down several feet, then plant and this then
saturates the soil, and prepares it for the coming sea-
son. If we want to get this material out, and this in-
cludes both the sodium and other cations, and we
have to flush enough of this through the soil and
work it out, so that they will sustain the viability of
the soil as a medium for plant growth.
I am not an expert in the heavy metals subject and I
have done only limited literature work in it.
COMMENT: Al Page, University of California,
Riverside. I would just like to comment on what I
prefer to call trace elements rather than heavy metals
because we eliminate certain things when we talk
about heavy metals. We eliminate certain things like
aluminum, beryllium, and many others. As far as a
trace element problem is concerned, I am sure that
there are a number of instances whereby toxic effects
of trace elements have been shown on plants where
soils have been irrigated or sludges have been applied
for a number of years. There are a number in
England. There are some in Sweden. There are some
in the United States. I think the most classic one is the
Berlin and Paris sewerage treatment plants. In a study
by Brody a rather acute copper and zinc toxicities to
certain plants is shown. I think the accumulations of
copper and zinc, if we can believe the data that are
reported, are upwards of thirty or forty thousand
parts per million in the surface of twenty centimeters
of soil.
COMMENT: Bill Bauer, Bauer Engineers,
Chicago. I would like to comment on the previous
comment about this paper by Brody. One of our fel-
lows was in Europe last December on vacation and
we asked him to check into the Berlin and Paris
sewerage farms to see what their current heavy metal
problems were. He was unable to discover the
existence of the Berlin farm. Evidently the land be-
came too valuable and they no longer use it, but the
Paris farm is still in operation. It has been in opera-
tion since 1885 and they still have about 7,500 acres
irrigated, sandy soil. He asked them about the heavy
metal problem and they didn't know they had one.
They have very excellent growth of vegetables. The
vegetables are the principal product and they market
these in Paris for the most part, and the only heavy
metal problem or trace element problem they remem-
ber was a deficiency of manganese which cut back
production and they had to add some manganese.
They were able to correct that situation, but they
never heard of Brody and they didn't know they ever
had a copper or zinc toxicity problem.
COMMENT: Belford Seabrook, EPA. Last July I
visited the Berlin sewerage operations. They had
about 700 acres under cultivation, however, the bulk
of the water went to East Berlin, and they didn't have
any clue as to what they were doing in East Berlin. I
talked to them about all kinds of problems including
those problems, and they said it was started in 1870
and that the current farming operation was started in
1895. Concerning a metals problem, they didn't know
what I was talking about. They said they didn't think
they had one. Nobody ever mentioned it to them. So,
if they had one, certainly the people who had been
operating it for 80 years aren't aware of it.
COMMENT: Bob Dean, EPA. On that Brody
paper, if you read it carefully, it is conjecture on his
part. And not actual going down and getting the stuff
first hand. There was an assumption that was made
about leaching these metals down into the ground-
water, and I can immediately see some ears perk up,
oh, we are going to poison our groundwater. It is very
hard to get metals to move in groundwater. Boron
will move. Chlorides and nitrates will move, but most
of the metals stick to the soil and have a very low
availability once they are on the soil.
-------
CHARACTERISTICS OF EFFLUENTS
61
COMMENT: Rufus Chancy, USDA. I hate to see
that one go by without giving the example published
by Blood ip the NAAS Quarterly Review. He
described among others, metal toxicity observations
from sludge and effluents on, a sandy sewerage
irrigation farm where they were growing a metal sen-
sitive crop, sugar beets, and they had a low pH. They
very easily solved the problem by liming, but that
doesn't say the problem doesn't remain with the soil
for subsequent pH drop.
COMMENT: Robert Williams, USDA, Washing-
ton, D. C. Just to change the subject slightly, Chuck
Pound's paper is a real good argument it seems to me
for having a good water treatment plant for the
drinking water so that people have a quality water to
drink, therefore you have a quality water to put on
the land.
COMMENT: A. Kaplovsky, Rutgers University.
We always had a truism that treatment is only as ef-
fective as your handling capability. So, if you are go-
ing to take out those thousand parts per million dis-
solved solids at one end, you are going to have to find
some place to put them, and that is the problem.
CHAIRMAN. Darwin Wright, EPA. I guess we
really haven't addressed the problem of treatment
plant sludges, maybe we should keep that in mind
when we enter into our workshop sessions on sludges
and utilization of sludges.
-------
A Regional View
On the Use of
Land for Disposal
of Municipal
Sewage and Sludge
R. J. SCHNEIDER
Environmental Protection Agency-
Region V
I am pleased to have this opportunity to partici-
pate in this very timely and most important research
needs workshop. The recycling of municipal sludge
and effluents to the land is a most appealing con-
servation concept, hut as the extensive list of topics
on the agenda illustrates, it is also a concept which is
plagued with a wide variety of problems, and this de-
spite the fact that the concept has been around as
long as man himself. It is encouraging to see so many
different skills and disciplines and interests represen-
ted here, and I am sure that this program will enable
all of us to become more knowledgeable in the state-
of-the-art of land disposal.
I spoke of this workship as being timely. From my
view, the concept of recycling as a conservation
practice, appealing as it may be, has been in conflict
with the throw-away philosophy of our society in
which planned obsolescence has become a way of
life. If we, as a society, have such a disregard for the
value of material things, how, then, can we convince
the decision makers and the public that recycling of
such an unappealing material as sewage is a viable al-
ternative to the prevailing attitude of getting rid of,
i.e., disposing of waste products? I would suggest that
one of the ways is through a symposium such as this,
which can capitalize on what I sense, hopefully, is the
beginning of a change in national attitude. There is
new concern for the environment; there is new con-
cern for the conservation of energy; and there is a
growing recognition that our resources are finite.
These are only a few of the trends that combine at
this point in our history to make the task of gaining
public acceptance of this concept of utilization of
wastes, as opposed to simply trying to get rid of them,
much less difficult than it would have been only a few
years ago.
Aside from posing such philosophical concerns, I
see my role as a regional participant in this workshop
as providing you with a regional insight into the use
of land for municipal waste treatment.
While research, per se, is not a responsibility of the
Regional Offices, the Regional Administrator does
have on his staff a small number of research experts
who provide him with the necessary liaison between
the nationally directed research activities of EPA and
the Regional Office. The Regional Office, as a whole,
does become involved in prioritizing proposed re-
gional research needs, in monitoring demonstration
projects, and each region has a Technology Transfer
Activity. However, I will speak primarily of those re-
gional functions through which the practical applica-
tion of new Municipal Waste Treatment Works Proj-
ects will proceed without Federal assistance, this
practical application is accomplished mainly through
two programs—through Water Quality Management
Planning and through the Construction Grants Pro-
gram.
Under Section 303 of the Amended Federal Water
Pollution Control Act of 1972, each State is required
to have a continuous planning process consistent with
the Act. The interim regulations governing this proc-
ess that relate to this discussion specify that the proc-
ess shall provide the States with the water quality
assessment and program management information
63
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64
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
necessary to make centralized, coordinated water
quality management decisions, that it shall provide
the strategic guidance for developing the Annual
State Program, and that the process will encourage
water quality objectives which take into account
overall State policies and programs, including those
for land use and other related natural resources. As
part of the overall State strategy, this planning proc-
ess, among other things, is to provide for the develop-
ment of basin plans, is to provide a mechanism for
determining State priorities for construction of pub-
licly owned treatment works and is to provide for
processing of waste-water discharge permits.
The planning process is designed to meet the three
milestone dates set by the law; these are 1977, 1983
and 1985. As a matter of first priority, planning is de-
signed to meet the requirements of 1977 for "best
practicable treatment" or compliance with water
quality standards, by classifying the waters of the
States to determine required treatment levels for the
purpose of issuing permits under the National Pollut-
ant Discharge Elimination System (NPDES). As dis-
tinct from requirements as established for 1977, the
law also established national goals of fishable, swim-
mable waters by 1983, and the elimination of the dis-
charge of pollutants by 1985. Long range planning
will be keyed to these goals.
As a prerequisite for a municipality to be consid-
ered for a Federal Construction Grant, a project must
be in conformance with the State's Water Quality
Management Plan for the area, and the plan must
also be approved by the Regional Administrator. The
specific project must also be certified by the State as
entitled to priority over other eligible projects from
the State's allocation of Federal Construction Grant
Funds.
Part of the guidance for Water Quality Manage-
ment Planning is contained in Title II of the Act en-
titled "Grants for Construction of Treatment Works."
Title II of the Law states that, "waste treatment
management plans and practices shall provide for the
application of the "best practicable waste treatment"
technology before any discharge into receiving wa-
ters, including reclaiming and recycling of water and
confined disposal of pollutants so they will not mi-
grate to cause water or other environmental pollu-
tion, and shall provide for consideration of advanced
waste treatment techniques." Title II further states,
"the administrator shall encourage waste treatment
management which results in the construction of rev-
enue producing facilities.for: (1) the recycling of po-
tential sewage pollutants through the production of
agriculture, silva culture, or aqua culture products or
any combination thereof; (2) the combined and con-
tained disposal of pollutants not recycled; (3) the
reclamation of wastewater; and (4) the ultimate dis-
posal of sludge in a manner that will not result in en-
vironmental hazards." The Act goes on to further
state that the administrator shall encourage waste
treatment management, "which results in integrating
facilities for sewage treatment and recycling, with
facilities to treat, dispose of, or utilize other industrial
and municipal wastes . . ." Section 208 of Title II
provides for development of area wide waste treat-
ment management plans and requires that any such
plan will provide for any requirements for the ac-
quisition of land for treatment purposes.
Section 403 of the Act deals with disposal of pol-
lutants in the ocean and instructs the administrator,
among other things, to develop other possible loca-
tions and methods of disposal or recycling of pollut-
ants, including land based alternatives. Section 405(a)
specifically prohibits the disposal of sewage sludge
from the operation of a treatment work in a manner
which would result in any pollutant from such sew-
age sludge entering the navigable waters except as
provided under a permit.
The new law also made a significant change in the
definition of treatment works, which is of vital impor-
tance to the recycling of municipal sewage and sludge
to the land. Contrary to the previous law, federal fi-
nancial participation may now be provided for "site
acquisition of the land that will be an integral part of
the treatment process or is used for ultimate disposal
of residues resulting from such treatment." The key
question for any land disposal project for purposes of
Federal participation in land costs is, "Does the use
of the land itself result in the treatment and renova-
tion of municipal wastewater?" Since solid materials
are one of the products of wastewater treatment and
can, under proper conditions, be applied to the land,
the application of municipal sludge to the land can be
therefore considered an integral part of land treat-
ment. Deposition of sludge in dumps, it should be
noted, is not considered treatment. This new defini-
tion of eligibility opens up a whole new opportunity
for consideration of recycling of municipal waste to
the land, since land utilization for waste treatment
now becomes much more competitive, cost wise, with
other conventional treatment methods where federal
funds are used. This opportunity has been further en-
hanced by federal assistance in the costs of relocation
of persons displaced by a project.
There are other sections of the new law that in-
corporate the disposal-utilization concept, and as you
can see from these references cited, one of the central
themes of the amendments is also an effort to re-
direct our national thinking away from the almost ex-
clusive preoccupation with disposal of sewage to the
-------
USE OF LAND FOR DISPOSAL
65
nation's waters. In the alternative the new law pro-
vides direction and incentives for the consideration of
the use of land for recycling, reuse and utilization of
sewage and sludge.
We in the Regional Office having responsibility for
review of State Water Quality Management Plans,
and Construction Grant Projects are guided by this
new national policy. We support and encourage the
continued development and practice of successive
water reclamation, reuse, recycling and recharge as
major elements in water resource management. At the
same time reclamation systems must be designed and
operated so as to avoid creating human health haz-
ards or damage to the environment.
Environmental compatibility must be a major con-
sideration in the selection of any method of waste
treatment and all projects for which federal assist-
ance is sought must have had a formal environmental
assessment prepared by the applicant. These assess-
ments are evaluated by EPA on the basis of EPA
regulations for carrying out the provisions of the Na-
tional Environmental Policy Act of 1969. EPA's
evaluations result in either of two actions. One can be
the issuance of a notice of intent to file an environ-
mental impact statement where the assessments are
either considered to be inadequate or where there is
significant environmental controversy. The alternate
action is the issuance of a "negative declaration"
where the assessment is considered satisfactory and
there is no significant environmental controversy.
While environmental compatibility must be a ma-
jor consideration in the selection of any method of
waste treatment, the use of land for waste disposal
always seems to create more environmental con-
troversy than any other process. From our experience
in Region V, we expect that all land disposal projects
will require a Federal Environmental Impact State-
ment. This is not true for projects involving more
conventional methods of waste treatment and is an
indication of a lesser degree of public acceptance of
land disposal as a viable alternative. This suggests
that one of the major challenges before this workshop
is to develop techniques for land disposal that can
compete environmentally with conventional process-
es. To cite one example where major controversy
arose which did not involve EPA, the Corps of En-
gineers in connection with a long range waste man-
agement study of the Chicago Metropolitan Area
proposed, as one alternative, acquisition of 445,000
acres of land in central Indiana for application of
Chicago's wastes. This provoked intense opposition
and reaction by indignant Hoosiers. The final report
of this study is not issued but I understand there has
been considerable modification to this alternative
which apparently was due in part to the reaction the
proposal received.
Because of the impending large outlay of federal
funds for the construction of municipal treatment
works, EPA is concerned with getting the most out of
this federal investment. The FWPC Act Amendments
raised federal financial participation to 75 percent of
the eligible costs and vastly increased the amount of
funds available. Cost-effectiveness therefore becomes
a major consideration in the selection of a waste
treatment process. A cost-effective analysis must ac-
company each application for a construction grant. A
principal element in cost-effective analysis is a com-
parison of alternatives, and proposed guidelines for
cost-effectiveness will require that the analysis com-
pare at least two methods for a particular situation.
Cost-effectiveness does not necessarily mean least
cost, but the most economical method will always
have an overwhelming advantage. Here again is a
challenge for this workshop.
I would now like to consider briefly the extent to
which land disposal is being used. Accurate informa-
tion on land treatment systems is difficult to obtain
and evaluate. As a generalization we do know that
only a small percentage of municipal wastcwater is
treated on the land, perhaps no more than three or
four percent. This seems to be quite low, but on the
other hand, growth of land treatment systems in the
United States will take place in a productive, envi-
ronmentally compatible, and cost-effective manner
only if enough information and knowledge of how the
land functions as a wastewater treatment system is
obtained. This knowledge must be of a depth and
quality that will permit sound design and reliable
performance prediction.
EPA has in the past and is now supporting re-
search, development, and demonstration programs to
acquire this knowledge and this also is a major chal-
lenge to this workshop. Several well known land dis-
posal projects in Region V have had the benefit of re-
search grants. These are the Fulton County Sludge
Utilization Project and the Muskegon, Michigan
Spray Irrigation Project. In addition, the Muskegon
Project has also received major construction grant
support. Once in full operation this project should,
through the research, development, demonstration
grant, provide a large amount of performance data
that is so badly needed for land treatment systems.
The Muskegon Project, from the non-technical stand-
point, already has provided an excellent example of
effective regional ization in an area with relatively
complex governmental relationships.
-------
66
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
1 have attempted in this brief discussion to present
a general picture of the Federal, State and local co-
operative actions necessary to bring a municipal
waste treatment project to completion. To further
summarize, we have new national water pollution
control legislation which challenges conventional
methods and conventional thinking. It sets new re-
quirements and goals that truly provide the impetus
for making the 1970's the decade of the environment.
Certainly the timing of this workshop is appropriate
to meeting the particular challenge in the law with
regard to finding land based alternatives for the
handling of municipal wastewater. We in the EPA
Regional Offices look forward to the practical appli-
cation of the results of your deliberations during this
meeting.
-------
The Physical Processes
In the Soil
as Related
to Sewage Sludge
Application
ELIOT EPSTEIN
United States Department of Agriculture
ABSTRACT
The physical processes in the soil are discussed
with particular reference to sewage sludge application.
Adding sewage sludge initially increases the hy-
draulic conductivity of a soil, but the conductivity
later decreases. This decrease appears to be due to
clogging of soil pores by microbial decomposition
products.
Soil structure af'ts soil witter, soil air, mechanical
impedence and root distribution. Organic matter,
through the activitv of microorganisms, increases soil
aggregation. Sewage sludge application increased the
stable aggregates 16 to 33 percent.
The low oxygen and high carbon dioxide contents in
the soil that result from high sludge application can re-
duce root growth, nutrient uptake and plant growth.
Other gas products of decomposition, such as methane
and etheylene. can be detrimental to plants.
INTRODUCTION
Soil physical processes are related to the mechani-
cal properties of the soil. These processes chiefly de-
pend on:
1. Texture or size distribution of particles.
2. Structure or the arrangement of particles.
3. Amount and type of organic matter.
4. Both amounts and kinds of exchangeable ions.
5. Mineralogical properties, particularly the kind
and amount of clay.
The physical properties influence:
I. Water retention and movement.
2. Aeration.
3. Plant growth - root penetration, plant develop-
ment, yield, water and nutrient uptake
4. Biological processes - gaseous production; or-
ganic matter decomposition; activity of microor-
ganisms and other soil biota.
5. Movement of salts, nutrients, and organic com-
pounds such as pesticides.
6. The microclimate of the soil - heat flow and
temperature.
The topics discussed in this paper will involve:
l.Soil water relationships- Energy relationships;
factors affecting water retention; and water
movement through soil.
2. Soil structure - Concepts and factors affecting
the structure of soils.
3. Soil air - Diffusion and composition.
Soil Water Relationships
State of Water In Soil
Water in the soil can contain energy. This energy
is essentially potential energy due to position or in-
ternal condition. The kinetic energy of soil water is
negligible. The total soil water potential (^) or energy
per unit quantity is defined as "The amount of work
that must be done per unit quantity of pure water in
order to transport reversibly and isothermally an in-
finitesimal quantity of water from a pool of pure
water at a specified elevation at atmospheric pressure
to the soil water (at the point under consideration)'".
Essentially this means that energy must be expended
67
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68
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to move water from one location in the soil to an-
other at standard conditions.
Total potential of soil water consists of four com-
ponents:
1. Gravitational potential fyz)
This is the potential due to the gravitational
force field and is dependent on the elevation of
water.
2. Pressure potential fyp)
This is the potential due to the overall pres-
sure being different from atmospheric pressure.
It can be positive if the pressure is above atmo-
spheric, or negative if the pressure is below at-
mospheric.
3. Matric potential (tj/m)
This potential results from the capillary and
adsorptive forces due to the soil colloidal or soil
matrix system. This potential has also been re-
ferred to as matric suction or soil water suction.
Matric potential is equivalent but opposite in
sign to matric suction.
4. Osmotic potential tys)
This potential is a result of the presence of
solutes in soil water, which in effect lowers the
potential energy.
Soil Water Retention
Water entering a dry soil surrounds soil particles
and fills the capillary pores. As the initial pores are
filled, the water moves into successive pores. As the
volume of water diminishes, the rate of movement
diminishes. Thus, as the suction increases and the soil
becomes drier, the conductivity of water decreases.
The relationship between soil water potential or
energy and soil water content is termed soil water re-
tention or soil moisture characteristic curve (Figure
1). As the water content decreases, the remaining
water is held more tightly by the soil particles, i.e.,
the adsorptive and capillary forces become greater.
Plant roots must exert energy to remove water
from soil. The drier the soil, the greater the amount
of energy that is needed. Thus, as the moisture con-
tent decreases, the soil water potential decreases.
The soil water retention curve is influenced by soil
texture (Figure 2). The greater the clay content, the
greater the water content for a given potential or suc-
tion. Soil structure also affects the shape of the soil
water retention curve. This is especially true in the
low suction range, i.e., high water content. An aggre-
gated soil will have large pores, whereas a compacted
soil has a lower total pore space and a lower volume
of large pores.
The addition of five percent sludge to a silt loam
soil shifted the water retention curve and increased
the amount of water retained at different suction
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SOIL WATER - % OF VOLUME
Figure 1 Soil Water Retention Curve'
O
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Figure 2- The Effect of Texture On Water Retention.
-------
PHYSICAL PROCESSES IN THE SOIL
values (Figure 3). Similarly, adding sludge compost
(Figure 4) increased the water content as various suc-
tion values.
Attempts have been made to relate to the state of
soil water to the water available for plant growth.
Two values have been used to indicate the upper
(wet) and lower (dry) limit of water in the soil that is
available to plants. The upper (wet) limit has been
called field capacity and the lower (dry) limit, the
wilting point.
Field capacity has been considered as the water
content at which internal drainage (gravitational
flow) ceases. However, it must be recognized that
water flow does not cease. Hence, no single value is
valid. The water potential value commonly used for
field capacity is -0.33 bar. Laboratory measurements
of field capacity are not reliable indicators of field
conditions. Soil structure, texture and profile charac-
teristics affect water retention in this low suction
range. Hence, field capacity should be measured in
the field.
o
CO
-16
-12
.2
c
-------
70
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
=K
w 9S
where:
i n j Q Volume
Jw = flux density = TT = 7 - zr. —
J At Area x Time
Kw= hydraulic conductivity
r^r= hydraulic potential gradient =
hydraulic potential
direction of flow
This is known as Darcy's Law and applies to water
movement under saturated flow. The hydraulic con-
ductivity (K) depends on soil characteristics and the
fluid properties. The soil characteristics that affect K
are texture, porosity, distribution of pores, and tor-
tuosity. The fluid properties are density and
viscosity.
In practice, K is separated into two factors; intrin-
sic permeability of the soil (k) and fluidity of
the fluid (f).
The permeability of the soil is therefore related to
the hydraulic conductivity as follows:
Kv
Pg
K =
where:
k = intrinsic permeability (cm2)
K = hydraulic conductivity (cm/sec)
v = viscosity (dyne sec/ cm2)
p = density (gm/ cm3)
g = gravitational acceleration (cm/ sec2)
When a soil is saturated, all of the interconnecting
pores are available for water conduction and hy-
draulic conductivity is at a maximum (Figure 1).
Unsaturated flow is difficult to describe quantita-
tively. The pores in an unsaturated soil are only par-
tially filled with water and the remaining pore space
is filled with air. The hydraulic conductivity is affec-
ted by the water content of the soil. Thus, as the soil
drains and the large pores are emptied of water, the
gravitation potential becomes less important and the
matric potential becomes more important. As the soil
water content and the soil matric potential decrease,
the hydraulic conductivity decreases vary rapidly.
The hydraulic conductivity varies for soils of differ-
ent textures (Figure 5). Adding sludge to soil initially
increases the hydraulic conductivity, but later it re-
turns to the original value (Figure 6). Johnson" found
a similar relationship for crop residues, and attri-
buted the decrease to clogging of pores by microbial
decomposition products.
Silt loam
Sand
10
0.1 D
-o
o
0.01 ^
3
s
0.001 1
x
0.0001
-60 -40 -20 0
Water Potential
Figure 5: The Effect of Texture On Hydraulic Conductivity
h.
-C
\
E
u
_x
>•
"u
3
-o
C
o
u
3
TJ
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X
20
16
12
8
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Digested Low
A
/ \
/
; \
Digested Raw Slud9e
/ High \ /\
1 /\/ \
I/ ^ V\ '' v
contror^-^J^ .--— y--,,^ ___...
20 40 60 80 100 120 140 160 180
Time Days
Figure 6- The Effect of Sewage Sludge On the Hydraulic
Conductivity.
Infiltration
Infiltration of water into soil depends on initial
water content, soil water potential, texture, structure,
and homogeneity or uniformity of the profile.
Changes during wetting, such as deterioration of sur-
face structure and sealing of soil pores, will reduce
infiltration.
When water is applied, the surface of the soil be-
comes saturated for several centimeters. Below this
region is a transmission zone which is nearly satu-
rated. Below this zone is a wetting zone where soil
moisture decreases rapidly to the wetting front. Sew-
age sludge and sludge compost will increase water in-
filtration by providing greater soil pore space and de-
creasing the potential of surface sealing.
-------
PHYSICAL PROCESSES IN THE SOIL
71
Soil Structure
Soil structure is the arrangement of soil particles.
Soil particles stick together to form clusters, aggre-
gates, and clods. It is the relationship of these aggre-
gates through their effect on the soil pore space that
influences the biological processes in the soil. Soil ag-
gregates and their arrangement affect soil water, soil
air, mechanical impedence and root distribution.
The formation and stability of soil aggregates de-
pend on the soil particle size distribution, organic
matter, cations and soil management. Because of the
multitude of arrangements that can be present in the
soil, it is impossible to describe soil structure direct-
ly. Generally, it is evaluated in terms of changes in
structure and the effects that these changes have on
aeration, aggregation, mechanical impedence, and in-
filtration.
Organic Matter
Organic matter influences soil aggregation
through the activity of organisms, primarily microor-
ganisms. Hubbell and Staten3 found that fungi pro-
duced the most aggregates, actinomycetes produced
an intermediate number, and bacteria produced the
least.
Adding sewage sludge and incubating for 175 days
increase the stable aggregates from 16 to 33 percent
(Figure 7). Although rapidly oxidizable organic mat-
ter may produce a desirable soil structure, continual
additions of organic matter will be necessary to main-
tain this structure as the cementing agents are decom-
posed. If no further organic matter is added, the res-
idual organic matter will decompose slowly with
some deterioration of soil structure^.
^ 40
OE
CO
ca
~c
t-M
00
* 20
kfcl
CJ
1*J
a.
5% Raw
5% Digested
Soil
Water
Soil aggregates tend to break up when wetted.
This is caused by differential expansion; that is, the
outside of the aggregate expands while the inside is
still dry. If aggregates are submerged in water, the air
is entrapped and the aggregates explode.
The beating action of raindrops disrupts aggre-
gates. The kinetic energy of rainfall is considerable
and depends on drop size. Figure 8 illustrates the ef-
fect of two drop sizes on porosity of a crust. Crusts
formed under small drops were considerably more
porous than those formed under large drops regard-
less of the rainfall rate. Crusts formed as a result of
raindrop impact have a dense layer 2 to 3 mm thick.
Erosion, which is the end result of dislodgement
and transport of soil particles, can be reduced mark-
edly by the addition of organic matter such as sludge
or compost to soil. Infiltration can be increased, thus
reducing the amount of water available for transport
of soil particles. Furthermore, the aggregates are
more stable and resistant to breakdown. A compost
mulch also will reduce the energy of raindrop
impact.
',0 f »K.O
Figure 7 The Effect of Sewage Sludge On Stable Aggregates'
Figure 8: Porosity of a Soil After Ten Minutes of Rain
Soil Aeration
The addition of sewage sludge to soil markedly af-
fects the diffusion of gases and the composition of the
soil atmosphere.
Diffusion of Gases
Gases diffuse through the soil when there are dif-
ferences in partial pressure or concentration of gases.
Conditions must be present that allow the gases to
move out or through the soil. Thus, diffusion of gases
and, consequently, the composition of the soil atmos-
phere depends on the porosity of the soil. In turn, the
-------
72
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
water content and the bulk density of the soil affect
the aeration porosity.
Composition of Soil Atmosphere
The soil atmosphere generally contains 0.25 per-
cent carbon dioxide, 20.73 percent oxygen and 79.02
percent nitrogen. Changes in the soil atmosphere af-
fect the biological processes of the soil.
Plant Growth. Root development is restricted
when oxygen levels decrease and carbon dioxide
levels increase. Plant species vary in their response to
changes in the soil atmosphere. For example, toma-
toes are sensitive to low oxygen concentrations, bar-
ley is less sensitive, and rice is relatively insensitive.
Plant growth also may be affected by the production
of toxic gases such as methane and ethylene.
Aeration influences the uptake of water and nu-
trients. High carbon dioxide concentration and low
oxygen concentration greatly reduce water absorp-
tion. Aeration affects potassium uptake, particularly
under conditions of high carbon dioxide. Other ele-
ments such as iron, nitrogen, calcium, phosphorus
and magnesium are also affected but to a lesser de-
gree. Under anaerobic conditions (less than two per-
cent oxygen) ethylene gas can be produced and may
injure crops8. Russell7 indicates that other gases such
as methane and hydrogen sulfide may accumulate in
the soil during anaerobic decomposition and reduce
root growth. The composition of the soil atmosphere
is primarily influenced by the presence of organic
matter and its decomposition.
Figure 9 illustrates the changes in carbon dioxide,
methane and oxygen below a trench filled with sew-
age sludge. The high methane and carbon dioxide and
the low oxygen levels could restrict root growth and
•— — ° Methane
Carbon Dioxide
trench filled with raw sludge. Root penetration was
considerably better with digested sludge (Figure 11).
Biological Changes. Aeration affects the micro-
bial population. The products of anaerobic decom-
position are different from those of aerobic decom-
position10. The different microbial populations will
affect such processes as nitrification and denitrifica-
tion. Anaerobic conditions are conducive to denitrifi-
cation, whereas aerobic conditions favor nitrifica-
tion.
Figure 9: The Effect of Sludge On Gages.
development and reduce plant growth. Figure 10
shows the restricted root growth surrounding a
Figure 10: The Effect of Raw Sludge In a Trench On Root Growth.
INTERPRETIVE SUMMARY
Sewage sludge and sewage compost increase the
retention of soil water. Adding sewage sludge initially
increases the hydraulic conductivity of a soil, but the
conductivity later decreases. This decrease appears to
be due to clogging of soil pores by microbial decom-
position products.
Soil structure affects soil water, soil air, mechani-
cal impedence and root distribution. Organic matter,
through the activity of microorganisms, increases soil
aggregation. Sewage sludge application increased the
stable aggregates 16 to 33 percent.
Incorporation of sewage sludge markedly influen-
ces the' soil atmosphere. The low oxygen and high
-------
PHYSICAL PROCESSES IN THE SOIL
73
Figure 11. The Effect of Digested Sludge In a Trench On Root
Growth.
carbon dioxide contents that result from high sludge
application can reduce root growth, nutrient uptake
and plant growth. Other gas products of decomposi-
tion, such as methane and etheylene, can be detri-
mental to plants.
REFERENCES
1. Aslyng, H. C. et at. (1962). "Soil Physics Termi-
nology", draft report. Int. Soc. of Soil Sci. Bull. 20.
2. Hillel, D. (1971). So/7 and Water. Academic
Press, New York.
3. Hubbell, D. S. and G. Staten (1951). "Studies on
Soil Structure." New Mexico Agr. Exp. Sta. Tech.
Bull. 363.
4. Johnson, C. E. (1957). "Utilizing the Decomposi-
tion of Organic Residues to Increase Infiltration
Rates In Water Spreading." Trans. Am. Geophys.
Union 38:326-332.
5. Peerlkamp, P. K. (1950). "The Influence On Soil
Structure On the Natural Organic Manuring by Roots
and Stubbles of Crops." Trans. 4th Int. Cong. Soil
Sci. 2:50-54.
6. Philip, J. R. (1957). "Evaporation and Moisture
and Heat Fields In the Soil." J. Meteorol. 14:354-366.
7. Russell, E. J. (1961). So/7 Conditions and Plant
Growth. London.
8. Smith, K. A. and S. W. F. Restall (1971). "The
Occurrence of Ethylene In Anaerobic Soil." J. of Soil
Sci. 22:430-443.
9. Taylor, S. A. and G. L. Ashcroft (1972). Physical
Edaphology. W. H. Freeman and Co. San Francisco.
10. Waksman, S. A. (1932). Principles of Soil
Microbiology. Williams and Wilkins Co., Baltimore,
Md. 2nd Ed.
-------
Physical Changes
to Soils Used for
Land Application
of Municipal Waste—
What Do We Know?
What Do We Need
to Know?
A. E. ERICKSON
Michigan State University
ABSTRACT
The beneficial effects of sludges on changing soil
physical properties is known while little is known
about the effects of heavy effluent loading. The trans-
fer of design experience from ordinary agriculture has
some difficulties. Therfore the greatest research need
in this area is field experimentation to develop soil
and crop management systems to optimize the amount
of effluent applied while maintaining maximum yields
of agricultural crops. Other research should consider
the effects of fiigh sodium concentrations in both
sludges and effluents and how to avoid or overcome
these effects.
INTRODUCTION
The physical changes in soils due to the applica-
tion of municipal waste will vary greatly depending
on the kind of soil, type of waste and quantity of
waste applied. Soils can range from coarse textured,
single grained and quite inert to fine textured, struc-
tured and very reactive. Municipal waste can range
from dry sludge to a dilute effluent. Application rates
can range from minimal application of sludge for nu-
trient additions to massive applications of sludge or
effluent for disposal or "dumping". In this discussion
it is assumed that neither the very light or the very
heavy application of waste is our concern but an op-
timum amount of waste to allow the utilization of the
land for agriculture or some other useful purpose. At
the same time the goal is to maximize the amount of
waste applied or minimize the amount of land used.
Because of the wide differences between the physical
properties and reactions of sludges and effluents, they
will be considered separately.
Sludge
Manures which in some ways can be considered as
similar to sludges have been used for millenia on
soils. Their physical effects and reactions with soils
are quite well understood. There is considerable
literature available on effects of sludges on the physi-
cal condition of soils. Sludges are advertised and sold
on the basis of their soil conditioning effects and fer-
tilizing nutrients.
In coarse textured, single grained soils the sludge
will condition an otherwise inert soil by its near
presence as a surface active and water absorbing ad-
ditive. The soil water properties are improved, the
water held at any tension is increased, and the soil
nutrient sorption capabilities are increased resulting
in a much more productive soil. In fine textured soils
which are capable of developing a structure but are
low in organic matter, sludge can supply the organic
matter for the formation of a stable structure which
could increase the infiltration and permeability rates,
decrease the bulk density, increase the aeration po-
rosity and improve the productive capacity of the
soil.
The amounts of sludge used in most cases is more
apt to be limited by the potential of the amended soil
to leak nutrients than for them to be overloaded
physically. This means that on most soils in a humid
climate 10 to 20 tons per year would be the maximum
that can be used. In very bad situations where the
75
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76
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
physical problems are critical such as mine spoil,
large quantities of sludge produce the immediate
physical soil improvement which is required for
reclamation.
There are several precautions that should be men-
tioned. Sludges that have large quantities of sodium
can have a deleterious dispersing effect on structured
soils and should be applied in small quantities,
leached before use or avoided. Sludges will not have
any beneficial effect on organic soils or soils that are
high in organic matter.
There are at least two areas for further research,
one concerns the amounts of a sludge that can be
used to improve a particular soil in its particular cli-
mate, the other which is probably more important
concerns the development of a best method for
spreading and incorporating a particular kind of
sludge into a particular type of soil to bring about the
best physical condition of the soil at a reasonable
cost.
Effluent
The consideration of the changes in soil physical
conditions due to effluent additions is more difficult
because there has been less research in this area. Also
many of the soils to which effluent is now being ap-
plied are coarse textured and would not be expected
to change physically. However, the best soils physi-
cally or hydraulically are the coarse textured soils
which give the poorest chemical treatment. The
medium and fine textured soils which have a greater
capacity to treat effluent have a lower hydraulic
capacity. There is the tendency to underdesign these
systems and overload the soils hydraulically which
will reduce crop yields or even destroy the crops.
Design data could come from agricultural drainage
and irrigation design. Actually agricultural drainage
design has severe economic constraints and is de-
signed to avoid calamities. Usually the design allows
for some yield reduction under severe weather situa-
tions. Irrigation design is based on the addition of
water to a dry soil in sufficient quantities to supply a
growing crop. Both of these practices are quite differ-
ent from adding the maximum quantity of effluent,
which is often higher in salts and solids to a soil and
grow economic crops.
In effluent farming the usual drainage criteria can-
not be used continuously during a growing season as
this would allow poor aeration conditions and greatly
reduce crop yields. At the same time effluent farming
will require the addition of effluent to moist, not dry,
soils which may have much lower initial infiltration
rates and permeability than experienced in normal
irrigation.
The hydraulic properties of medium to fine texture
soils decrease when moist. Under continual infiltra-
tion the rate of infiltration drops. Moist subsoils can
have permeabilities that are a fraction of permeabil-
ity they would have when partially dried by drainage
and by roots activity. These changes are due to the
hydration and swelling of the natural peds under con-
tinually moist conditions which reduces the large
pores. If organic matter is present, oxidation-reduc-
tion potentials can drop and cause further structural
deterioration. Upon drying the peds shrink, the struc-
ture is stabilized and the infiltration rates and per-
meabilities recover. Effluent farming therefore will
have to include drying cycles for crop and soil ma-
nipulations and some soils may need drying cycles
for the recovery of desirable physical soil condi-
tions.
There is a very wide diversity among soils. The as-
sumption that because the soil on the Pennsylvania
State Effluent Project took two inches of effluent per
week therefore all intermediate texture soils will do
the same is not valid.
The greatest research need in land treatment of ef-
fluent as it effects the physical changes in soils and
crop yields is for field experiments with effluent ap-
plication on medium to fine texture soils which have
adequate artificial drainage. The objective of this re-
search should be to maximize the quantity of effluent
that can be applied and still maintain crop yields.
Another potential problem is the high sodium con-
tent of many effluents. Sodium can cause the clay in
the soil to disperse, the structure to degrade and the
surface soil to seal. This causes the infiltration rate
and permeability to drop markedly. There is a wealth
of data in this area developed for our arid regions
that can be applied elsewhere however some experi-
mentation with the soils involved and the influence of
natural rainfall should be studied.
Effluents that contain considerable soils could
cause pore plugging problems but reductions in ap-
plication rates and allowing for drying cycles should
reduce this problem. Effluents that contain consid-
erable BOD could cause an increase in carbon
dioxide and a reduction in oxygen in the plant root
zone. This could cause an aeration problem for plants
growing on the soil if the application rate is not
reduced.
Sewage
Because sewage has more organic matter than ef-
fluent and is more biologically active from a physical
soil point of view it is a better soil amendment than
effluent alone. The solids might cause a plugging
problem but the extra organic matter would have a
greater soil conditioning or soil structure stabilizing
effect similar to the effect of manuring. The develop-
-------
PHYSICAL CHANGES TO SOILS
merit of processes to remove the public health hazard
of land treatments of raw sewage would greatly sim-
plify the present systems which remove the soil con-
ditioning BOD from the effluent and concentrate
other materials, often to toxic concentrations, in the
sludge.
CONCLUSIONS
There is more known about sludges and their ef-
fects on changing the physical properties of soil than
there is about effluents. Field experiments to deter-
mine the maximum amounts of effluents that can be
applied to medium textured soils and produce good
to maximum crop yields in combination with existing
rainfall are necessary. The influence of sodium in ef-
fluents or high sodium sludges should be researched
to determine the limits of particular soils or practices
that might be used to accomodate time.
DISCUSSION
QUESTION: Ray Harris, United States Forest
Service. I was interested in the comment on sands and
it was also eluded to by several of the other speakers,
and I know that when we start applying the large
rates that we are going to have, of course, a chain
system. We are creating what we might call a new soil
or a pseudosoil whereby we are changing all the
properties that the original soil had. Don't you think
that over a period of time with proper management,
and these are long term things, that we would end up
in sands with a much better renovator with a system
that has a lot of properties of finer soils, but because
of organic matter has better renovation built in'' Of
course aeration ability to accomplish the purposes
that we are about to do since in the course of soils
the water is much more viable. The sands in the long
term run might be our better soils for renovation pur-
poses.
ANSWER: I think that you are right. Using the ef-
fluent on sands we will build these soils up, but if
what my chemist friends say is true, these will begin
to leak nutrients. Phosphorous will leak from these
soils very readily. Then I think we are in a problem
and this is why we have to back off on sands
Hydraulically, they are good, but renovatively, I
think they are not so good.
-------
Soil Microbiological
Aspects of Recycling
Sewage Sludges and
Waste Effluents
on Land
ROBERT H. MILLER
Ohio State University
and
Ohio Agricultural R&D Center
ABSTRACT
The biological component of soil which includes
bacteria, actinomycetes, fungi, algae and soil micro-
and macroanimals makes significant contributions to
waste recycling by decomposing waste organic com-
pounds; eliminating some environmental toxins; elimi-
nating pathogenic microorganisms; involvement in the
nitrogen, phosphorus and sulfur cycles; and by in-
fluencing the solubility and mobility of inorganic ions
in soil. Our present knowledge of these microbial reac-
tions is reviewed and used to emphasize significant
areas of needed research.
INTRODUCTION
The biological component of the soil has been
recognized to be of primary importance to the suc-
cessful functioning of the "soil filter" during recy-
cling of sewage sludges and effluents. Likewise, under
certain situations unwanted biological reactions may
occur which are detrimental to the integrity and
functioning of the soil filter. This biological compon-
ent includes bacteria, actinomycetes, fungi, algae, the
soil micro- and macrofauna, and higher plants. Since
other papers in these proceedings will discuss the
contributions of higher plants to waste recycling in
soils, this paper focuses primarily on the reactions in-
volving soil microorganisms with a brief discussion of
some potentially significant reactions involving the
soil macrofauna.
The biological component of soil makes significant
contributions to waste recycling in five main areas: 1)
decomposition of organic compounds contained in
sludge and waste effluents, 2) detoxication of some
potentially problematic organic materials contained
in sludges and effluents e.g., detergent residues, pesti-
cides, and petroleum hydrocarbons etc., 3) elimina-
tion of pathogenic microorganisms, 4) participation
in the cycling of nitrogen, phosphorus, and sulfur,
and 5) in the reactions which influence the solubility
and mobility of inorganic ions.
This paper will present as concisely as possible our
present understanding of these microbial reactions,
while identifying those areas which are less well un-
derstood and which require further research.
Nature of Soil Biological Component
Soil microorganisms in the plow layer of agricul-
tural soils often reach high numerical populations.
Estimates of 107 bacteria, 106 actinomycetes, and 105
fungi per gram of soil are typical values obtained by
plate counts on various artifical media. Direct micro-
scopic counts for soil bacteria are usually higher with
109 cells per gram of soil a common figure. Bacterial
populations in the plant rhizosphere are commonly
10 to 100 times greater than the normal soil popula-
tion with smaller population increases noted for ac-
tinomycetes, fungi, and algae. Soil fungi become the
dominant numerical group of soil microorganisms in
the litter layer (A()) and (A) horizons of acidic forest
profiles. In both agricultural and forest soils the
microbial population is concentrated primarily in the
surface 15 cm organic matter rich region of the soil
and numbers decrease rapidly with depth.
Algae are common to all soils and are most abun-
dant at or near the soil surface. Population estimates
usually range between 10-* to 105 per gram of soil31.
79
-------
80
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Biologists in the United States have usually discount-
ed the significance of algae in normal soils and have
considered them of economic significance only in
fields of paddy rice or in desert algal crusts. In both
instances the primary benefit is ascribed to denitro-
gen fixation by some species of blue-green algae.
Some biologists, especially in the Soviet Union, con-
sider that soil algae make other important contribu-
tions by producing plant growth stimulants and by
providing a significant source of soil organic mat-
ter". Regardless of the previous literature, it seems
important that the significance of soil algae be re-
evaluated under systems of effluent irrigation. Here
high soil moisture, high humidity, and high nutrient
levels may provide an environment conducive to the
development of large algal populations.
Our understanding of soil protozoa is even more
fragmentary than that for soil algae. An excellent re-
view of these soil microanimals is provided by Stout
and HealJ 7. Populations of 103 to 105 per gram of wet
soil are commonly recorded for temperate soils of
moderate fertility. The primary function of protozoa
is thought to be that of predation of soil bacteria, e.g.,
the rapid disappearance of coliform bacteria in soil
may result from predation by soil protozoa. In addi-
tion, soil protozoa may also affect organic matter
cycling of soils by their predation and digestion of
soil bacteria. Vegetative cells of soil protozoa nor-
mally are found in water films and water filled soil
pores. Thus soil protozoa could become of greater
importance in soils being irrigated with secondary ef-
fluent.
Soil macroanimals are a diverse groups of organ-
isms which include nematodes, earthworms, flat-
worms, slugs, snails, centipedes, millipedes, woodlice,
arachnids and larval, adult and nymph stages of in-
sects. For a series of detailed reviews on some of the
more significant groups of soil animals see Surges
and Row1". Because of the diversity and complexity
of this broad group of soil organisms only general
comments on their significance in waste recycling
seem appropriate. As a group soil animals have also
been largely ignored by biologists in the United
States, with the possible exception of earthworms. It
is this author's opinion that soil macroanimals may
be of considerable significance in soils which are
being used for waste recycling. Primary functions in-
cluded the digestion of organic materials, the mixing
of surface applied residues and sludges with the soil,
and changes in soil aeration and water infiltration. In
the latter cases, insect or earthworm burrows might
provide a means for effluent to move into and
through soil rapidly without adequate renovation.
Numerous estimates of bacterial biomass have been
calculated. The data as summarized by Miller19 show
a mean value of bacterial biomass to be 300 g/ m2
(2800 lb/ acre). In most arable soils, the amount of
bacterial biomass is commonly estimated to be some-
what less than that of fungi, but to exceed that of the
algae, protozoa, and nematodes combined':. Esti-
mates of the biomass of actinomycetes is not readily
available but is generally considered to be equal to
that of the true bacteria. Jenkinson:" estimated that
the soil biomass contained 2.3-3.5 percent of the soil
carbon.
Application of sewage sludge or other high organic
wastes to soils increases soil microbial numbers 4".
Representative data for changes in the population of
bacteria and actinomycetes and soil fungi during the
decomposition of an anaerobically digested sewage
sludge is shown in Figures 1 and 2. Numbers of bac-
teria and actinomycetes were generally directly re-
lated to the sludge loading rate (Figure 1). Within a
treatment maximum numbers were usually found af-
ter one month incubation and decreased after three
and six month incubation. The fungal population also
increased in response to the quantity of sludge but the
increase was not as pronounced as with bacteria and
actinomycetes (Figure 2). This same increase in the
fungal population was not evident in the Paulding
clay incubated under saturated conditions. Neither
did the number of fungi decrease substantially with
increasing time of incubation as was true for the bac-
teria and actinomycetes. This probably represents a
profuse development of heavily sporulating species
during the initial period of incubation with these
spores remaining viable through the three and six
month incubation period.
Limited data is available on population changes in-
duced by irrigation with secondary effluent. Unpub-
lished data by Goodfellow from the Pennsylvania
State University effluent disposal studies have shown
a slight increase (less than 1 log) in the number of
aerobic heterotrophic bacteria in the surface one to
two inches of soil. These increases were related to the
quantity of effluent applied. Small population in-
creases might be expected because of the low organic
loading associated with most secondary effluents.
Microbial populations may increase in soils used for
effluent recycling where perennial forages add ap-
preciable quantities of roots, stubble and rhizomes
annually. The changes which might occur in the
microbial population of forest soils to which effluent
is applied remains an unanswered question, but would
probably be more dramatic than in agricultural soils.
For example, populations of fungi and some soil ani-
mals which often dominate forest soils and litter may
decrease in significance under conditions of intermit-
tent soil saturation and high humidity.
Few studies have attempted to evaluate qualitative
changes in the microbial population when sewage
sludges and effluents arc applied to soils. Miller4"
-------
SOIL MICROBIOLOGICAL ASPECTS
81
H(H)
600
4OO
o 200
? 0
O 800
~ $00
S 4OO
5 200
o
o
(0 0
o
£ 1500
ffi
1100
roo
0 90 224
3 mo
0 9O 224
OFTOKEt SAND
6 mo HI
CELINA SILT LOAM
PAULDING CLAY
0 9O 224
C3
Sludge amendment, tons (metric)/ho
Figure 1 Plate Count ol Hactm.i .mil Aiiinoinyi-i-ies In Three
Soils Allei liicuhiilion with Aiiiierobically Di^csleil Si-wage Sludge
tor One, Three and Six Months (The Temperature ol Incubation
Was Equivalent to Spring-Summer Temperatures In C'olumbus,
Ohio"' )
40 O
300
200
100
0
S 400
»
f 300
O
i 200
f 100
•3
u_
0
8OO
6OO
4OO
200
I mo
11
3 mo
3 mo
3 mo
6 mo
OTTOKEE SAND
6 mo
in
K CELINA SILT LOAM
PAULDING CLAY
• FC
C3 Sot
0 90 224 0 90 224 0 90 224
Sludge omendmenl, tons (metric)/ho
Figure 2 Plate Count of Fungi In Three Soils After Incubation with
Anaerobically Digested Sewage Sludge for One, Three and Six
Months. (The Temperature of Incubation Was Equivalent to Spring-
Summer Temperatures in Columbus, Ohio'".)
characterized 354 bacterial isolates from two soils
amended with an anaerobically digested sewage
sludge. The data in Figures 3, 4 and 5 is from this
study. Among the more significant findings of this
study was the chiingc in the bacterial population from
one dominated by gram positive bacteria m the un
amended soil to one where gram negative bacteria
made up more than 50 percent or greater of the iso-
lates from sludge amended soils. Accompanying this
change in gram reaction was a reduction in the num-
ber of spore farmers, a decrease in average cell size.
CHARACTER
RODS
COCCOBACILLARY
SPOKES
GRArA —
GRAWV
COLONY
PIGMENTATION
°/o OF ISOLATES
25 50 75
too
89 I I CONTROL.
9O (AETK1C
TON
Z24 METRIC
TON
25
50
75
100
Figure 3: Selected Morphological and Cultural Characteristics of
Bacterial Isolates from Sludge Amended Soils. The Isolations Were
Made After One Months Incubation with an Anaerobically Di-
gested Sewage Sludge. The Numbers to the Left of the Key In-
dicate the Number of Isolates Characterized4".
CHARACTER.
RELATIVE
GROWTH
OF ISOLATES
90 7B
GROWTH
AT
GROWTH
IN N8CI
1OO
roo
Figure 4: Selected Growth Characteristics of Bacterial Isolates from
Sludge Amended Soils. The Isolations Were Made Alter One
Months Incubation with an Anaerobically Digested Sewage
Sludge4".
-------
82
RKCYCLINC, MUNICIPAL SLUDC.KS AND KWI.l 1LNTS
CHARACTER
% OF ISOLATES
Z5 50 75
1OO
HVPKOLVSI5 OF
STARCH
GELATIN
UTILIZATION OF
CITRATE
89 I I CONTROL
127 Eiil 90 METRIC
TB2Z4- METRIC
TON
ACID PRODUCTION
FK.OISA
PROPORTION OF
CATALASE
CYTOCHROtAE
OXIPA^E
UR.EAS.E
IOO
Figure ? Selected Biochemical and Enzymatic Activity of Bacterial
Isolates from Sludge Amended Soils. The Isolations Were Made Af-
ter One Months Incubation4".
and an increase in colony pigmentation among the
isolates from sludge amended soils. Bacterial isolates
from sludge amended soils also differed physiologi-
cally from the normal soil bacterial population. Iso-
lates from sludge amended soils generally grew at a
taster relative growth rate, grew better at 5°C but less
well at 35°C, and tolerated a higher concentration of
NaCl. Biochemically the isolates from sludge amend-
ed soils had increased catalase and cytochrome oxi-
dase activity, were better able to utilize citrate, but
were less able to hydrolyze starch or produce acid
from a series of carbohydrates. Lastly, the isolates
from sludge amended soils showed a general increase
in resistance to antibiotics. These data provide infor-
mation that the soil microbial population does
change (perhaps expectedly) in response to the addi-
tion of waste materials. Although these types of
studies are of academic interest, it is doubtful if they
will provide any information which will help us in
better managing soils to which wastes have been
added.
CONCLUSIONS
Quantitative and qualitative studies of microbial
populations presently add little knowledge directly
applicable to managing waste amended soils. Greater
emphasis should be given to evaluating any changes
which might occur in significant microbial transfor-
mations and functions in sludge and effluent amended
soils. Particular emphasis should be given to the plant
rhizosphere, and to forest soils where effluent appli-
cations may have their greatest effects.
Considerable rescaich emphasis should he given to
studies on the changes in earthworm population and
that of other significant soil animals alter sewage
sludge and waste effluents have been applied to soils.
For example, earthworms have been shown to ac-
cumulate heavy metals in sludge amended soils',
could be important in waste comminution in certain
methods of sludge application, and could alter water
infiltration to the detriment of soil renovating capa-
bilities.
Lastly, soil algae could become a highly significant
component of the soil microbial population with ef-
fluent irrigation. Their contribution to dmitrogen
fixation and organic matter accumulation may have
to be evaluated.
Decomposition of Organic Compounds of
Sewage Sludges and Effluents
One primary function of the biological component
of the soil is the degradation of the organic com-
pounds of sewage sludges and effluents.
Anaerobically digested sewage sludges contain
about 25 percent organic carbon on a dry weight
basis*. During the process of anaerobic digestion the
waste organic solids are stabilized by the almost com-
plete microbial fermentation of carbohydrates (the
exception is cellulose) resulting in a 60-75 percent re-
duction in volatile solids. The residual organic ma-
terial consists of a mixture of microbial tissue, lignin,
cellulose, lipids, organic nitrogen compounds, and
humic like materials. The organic carbon content of
undigested primary sludge, aerobically, digested, and
activated sludges are highly variable but generally
higher than anaerobically digested sludge. The
chemical analysis of the primary and activated
sludges will be similar to microbial cells which domi-
nate these materials. This author had no knowledge
of a detailed chemical analysis of an aerobically di-
gested sludge.
Secondary effluent from properly operating acti-
vated sludge plants, trickling filters, or lagoons con-
tains relatively low levels of organic compounds. A
typical secondary effluent was considered to have a
BOD of 25 mg/ 1 and a COD of 70 mg/11 \ Limited in-
formation is presently available on the chemical
analysis of the organic compounds of secondary ef-
fluent"44}''. A portion of the organic materials mea-
surable by BOD are derived from sludge particles
carried over from the treatment system, and would
have a chemical composition similar to that of micro-
bial tissue. Part of the BOD of secondary effluent is
also in the colloidal and soluble states and would
have a chemical analysis similar to that of the parti-
culate materials.
-------
SOIL MICROBIOLOGICAL ASPECTS
The less readily decomposable organic compounds
of secondary effluent (refractory organics) are esti-
mated by the difference between the values for COD
and BOD. These organic compounds are those which
are considered more slowly degradeable e.g., phenols,
detergents, fats and waxes, hydrocarbons, cellulose,
lignin, tannin, plant and bile pigments, pesticides, and
humic compounds.
As might be surmised from a consideration of their
variable chemical properties, waste organic com-
pounds will decompose at varying rates. Thus an-
aerobically digested sewage sludge is not degraded
rapidly in soil"". A maximum of only 17-20 percent
of the carbon from anaerobically digested sludge
amendments of 90 and 224 metric ton/ ha was
evolved as CO: during a six month period at soil tem-
peratures equivalent to spring-summer or summer-
autumn in Columbus, Ohio (Figure 6). The difference
in slope with time shows that the more readily avail-
able substrates were decomposed during the initial
month (10-13 percent of the carbon evolved) with
markedly reduced CO2 evolution during subsequent
months. These data certainly suggest that the addition
of anaerobically digested sewage sludge to soils will
result in an accumulation of organic matter in soils.
Another significant result from the study was the ob-
servation that at the rather high rates of sewage
sludge loadings employed, the rate of which the car-
bon was evolved as CO7 by microbial activity was
largely independent of soil properties.
Undigested primary sludge or activated sludge will
contain organic residues which are more readily de-
gradable. Data from the ARS, USDA Progress Re-
port' report that raw sludges showed an average loss
of 27 percent carbon after 54 days incubation in con-
trast to less than ten percent loss of carbon from di-
gested sludge.
Limited data is currently available on the rate at
which the organic compounds of waste water efflu-
ents are decomposed in soil. Thomas and Bendixen48
studied the rate of degradation of septic tank effluent
in sand lysimeters and secondary effluent in lysi-
meters of sand and a silt loam soil. About 80 percent
of the organic carbon from septic tank effluent was
decomposed during 82-425 day closing cycles with
little difference due to duration of closing, tempera-
ture or loading rates. Only 68 percent of the organics
of secondary effluent was degraded in the sand lysi-
meters during 513 and 760 day dosing periods while
89 percent was degraded during a 513 day dosing of a
single lysimeter containing a silt loam soil. These
data would at least suggest that the organic com-
pounds of secondary effluent are readily decompos-
able and would not by themselves result in the accu-
mulation of soil organic matter. However, many of
3 mo
90 Ton (melnc)/ho
6 mo
1 j
I 1
i-i
i
L !
I 8 •
^ ° 0
A
1 1 1 1 1 1 1 1
2468
OUokee sand
Cehna silt loam
Poulding clay
l 1 1
10 12
Monthly Degree Days, x 10 3
Figure 6 Decomposition of Anaerobically Digested Sewage Sludge
In Soil with Time as Influenced by Temperature Data Points for
Each Incubation Time Were Calculated from Measurements of
CX>2 -C Evolution from Three Soils Amended with 90 Metric Ton
of Sludge/ Ha. Degree Days =
N
XMT "*" X_
vmtl
X 30.
Where X M-( = Mean Daily Mas Temp. During a Month (!•),
X mi=Mcan Daily Mm Temp During a Month ("!•), N- No of
Months.
the soil management systems proposed for recycling
and renovating effluents (especially in the humid,
high rainfall areas of northeastern United States) uti-
lize forage grasses extensively. Reed Cannarygrass is
an example of grass commonly mentioned as desir-
able for effluent disposal sites. Stubble root and
rhizome accumulation may result in a net increase in
soil organic matter.
CONCLUSIONS
Recycling sewage sludges on land will present dif-
ferent management problems from those associated
with effluent recycling. As noted previously, applica-
tions of anaerobically digested sewage at the rates
presently being recommended for soils will result in a
net accumulation of soil organic matter. Organic
matter in soils is normally considered a valuable re-
source; because of its influence on soil structure,
water holding capacity, water permeability, cation
exchange capacity, and adsorption of heavy metals.
However, frequent large applications of sewage
sludge or single massive applications could result in
an accumulation of organic matter which would ad-
versely affect ion solubility and availability, plant
growth, or environmental quality. For example, ex-
periences at the Paris and Berlin sewage farms has in-
dicated that organic matter accumulation was asso-
ciated with "exhausted soils"4\ The primary reason
-------
84
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
cited for the poorer plant growth was an accumula-
tion of Cu and Zn by the soil organic matter in a
form available and toxic to the plants. Excessive ac-
cumulation of sludge organic matter might adversely
affect the soil atmosphere, with the associated prob-
lems of odor, reduced root development, and in-
creased mobility of many heavy metals. It seems im-
portant, therefore, that further information be ob-
tained on what the desirable level or organic matter
accumulation might be for a given management sys-
tem e.g., strip-mine spoil reclamation vs. agricultural
use.
Adequate management of soils to which sewage
sludges are being added requires further information
on the rate of sewage sludge decomposition which
might be expected with different methods of sludge
application or different loading rates and frequencies.
Thus the rate of sludge decomposition might vary
considerably when applied by surface irrigation, soil
incorporation, deep plowing, injection, etc. Likewise
the expected rate of sludge decomposition will differ
when applied in a single massive application versus
repeated smaller additions.
One other consideration in managing sludge dis-
posal sites is a concern for possible problems which
might arise when these sites are abandoned, whatever
the reason for abandonment might be. During the
period of regular sludge application these soils will
have reached a new higher equilibrium level with re-
spect to organic matter. When further additions are
halted, the organic matter will begin to decrease to a
new organic matter level characteristic of the soil,
climate, and soil management practices. What signif-
icance this new organic matter level will have on
heavy metal toxicity and movement, nitrogen trans-
formations, and other properties influencing plant
growth must remain speculative.
One last consideration will be a suggestion that
some parameters other than BOD or COD be used to
define the organic matter content and decomposabil-
ity of liquid wastes in soils. These tests were designed
for use in evaluating the environmental impact of
waste discharge into streams and lakes, and have
proven useful and meaningful in designing sewage
treatment systems. Their applicability as a meaning-
ful term in recycling and disposing of organic wastes
in soils is questionable.
Elimination of Environmental Toxins
Municipal waste effluents and sewage sludges con-
tain varying concentrations of a variety of organic
and inorganic substances which are considered po-
tential environmental toxins. Among the compounds
frequently found are phenolic compounds, the chlori-
nated hydrocarbon pesticides and chlorinated bi-
phenyls, detergent residues like ABS and NTA, petro-
leum products, heavy metals, etc. The concentration
of any one of these compounds which would reach
the soil during waste recycling would depend primar-
ily upon the industries utilizing the sanitary system,
the degree of industrial pre-treatment, and the effi-
ciency and type of municipal waste treatment facility.
Normally the concentration of any one of these com-
pounds reaching the soil will be low.
The groups of organic compounds listed above are
chemically diverse and few generalizations on micro-
bial degradation or detoxication in soil can be
made". For a more detailed treatment of microbial-
metabolism of many of these compounds the readers
are referred to the following papers: phenols'"'24,
herbicides"2", insecticides34, fungicides and nemato-
cides4', hydrocarbons'9", and detergent residues"".
CONCLUSIONS
Under normal circumstances the potential en-
vironmental toxins which will reach the soil in waste
effluents and sludges should not cause environmental
problems. This conclusion was derived from consid-
eration of the initially small concentrations normally
present in these waste materials and by the ability of
the soil microbial population to metabolize or detox-
ify a large number of them. In the latter case it is im-
portant that physical and chemical adsorption on soil
particles provide sufficient retention time for micro-
bial activity to proceed.
What does seem important is that each community
or sanitary district contemplating waste recycling on
land be aware of these potential hazards and ade-
quately characterize their waste materials with re-
spect to them. If the risk is severe, steps should be
taken to remove the toxin prior to land treatment. If
the risk is moderate, adequate monitoring of the per-
sistence, mobility or environmental effects of this
compound must be provided. It is also imperative
that our industries, responsible government agencies,
and our scientific community continually evaluate
potentially harmful synthetic or natural chemicals so
that steps can be taken to eliminate them from use if
proven harmful.
Research in this area should continue to focus on
the structural basis for resistance to microbial de-
composition of a variety of synthetic organic com-
pounds. Emphasis should also continue on under-
standing the metabolic schemes by which compounds
presently reaching our soil environment are meta-
bolized by the soil microflora.
-------
SOIL MICROBIOLOGICAL ASPECTS
85
Elimination of Pathogenic
Microorganisms
Recycling of sewage, primary and secondary ef-
fluents or liquid sewage sludges on land may present
a potential health hazard because of the hurrjan and
animal pathogens which these wastes contain. Among
the common pathogens found in these waste materials
are the bacterial pathogens Salmonella, Shizella, My-
cobacterium, and Vibro comma; the hepatitis viruses,
enteroviruses and adenoviruses; and the protozoan,
Endomocba ftisttilyticir". Cooke and Kabler1' have
also shown the several fungi capable of causing dis-
eases in man are present in sewage and sewage pol-
luted water. Cook'2 found human pathogenic fungi
and fungal allergens in sewage sludges and sludge
amended soils.
Since all large scale proposals for land application
of secondary effluents include plans for prior disin-
fection of effluent, the concern for survival of patho-
gens in soil would seem unfounded. Likewise, most
smaller municipalities would also be required by
state regulations to provide adequate disinfection for
effluents being applied to land. Yet for two reasons
the health hazards associated with land disposal of
waste effluents still remains a valid concern. First,
methods of disinfection are not uniformly effective
against all potential wastewater pathogens. Viruses in
particular may survive usual chlorination proce-
dures'" . Second, effective day to day disinfection of
effluents may be limited by human and mechanical
failure. No documentation of this latter point is pres-
ently available.
Sewage sludges provide a slightly different prob-
lem. Anaerobic digestion of sludge results in a signif-
icant reduction in numbers of pathogenic microor-
ganisms, but does not result in complete elimination
of pathogens'"1. In addition, many treatment facili-
ties do not disinfect sludges prior to land application.
Regardless of the reason, the uncertainty of knowing
whether or not pathogenic microorganisms are still
present in sludges being applied to land makes infor-
mation on the survival in and movement of pathogens
through soil a significant concern.
Data from the extensive studies by McGauhey and
Krone'f and Krone:" have shown that pathogenic
microorganisms are largely retained at or near the
soil surface and that movement through the profile is
not considered a severe problem. Some doubt about
the movement of virus particles still remains, how-
ever. Once the pathogenic microorga/iisms are re-
tained the next consideration is the length of survival
of these microorganisms in the soil matrix.
Most studies have indicated that pathogenic and
indicator bacteria are eliminated from soils rather
rapidly. The due back curves of Van Donsel et af"
for fecal coliforms and fecal streptococci as shown in
Figure 7 are typical of those commonly but not al-
ways obtained. Survival of bacterial pathogens and
indicator bacteria in soil for longer time periods have
been reported"46. Whether the typical due back
curves are descriptive of the die back of pathogenic
viruses is still an open question, and one which
should be given a high research priority.
ion
-------
86
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
of pathogenic microorganisms should not be a factor
limiting the applicability of recycling wastes on land.
This does not mean that reasonable caution should
not be employed to limit aerosol formation during ir-
rigation of waste effluents, that the general recom-
mendation that waste materials not be applied to
crops which will be consumed raw be rescinded, or
that the runoff from fields used for recycling not be
controlled. All municipalities or sanitary districts
employing land for recycling of wastes should also be
prepared to adequately monitor the soils and ground
for the survival of pathogens.
It is also imperative that strong research priority be
given to studies on the movement and survival of
pathogenic viruses in soils. These studies should in-
clude field studies which evaluate survival under dif-
ferent conditions of management for effluent and
sludge disposal sites. It would be hoped that some
method could be developed that would allow realistic
monitoring of soils and groundwater supplies for
pathogenic viruses.
Continuing efforts should be made to improve our
understanding of the biotic and abiotic factors affect-
ing the survival of pathogenic microorganisms in
soils. Methodology should be evaluated and im-
proved for the monitoring of soil and groundwater
contamination by pathogenic bacteria or fungi.
Microbial Reactions Which Influence
the Mobility and Plant Availability
of Ions In Soil
Of the concerns which might limit the recycling of
effluents and sludges on land, those involving the ac-
cumulation and movement of N, P, and various inor-
ganic ions are potentially the most serious. The soil
microbial population is directly or indirectly in-
volved in the soil reactions of most of these elements,
and greatly influences the success of waste recycling
on land.
Nitrogen
The microbial reactions involving nitrogen which
are of primary significance to waste recycling are
mineralization, nitrification and denitrification.
Secondary effluent contains rather modest concen-
trations of both NH4+- N (9.8 mg/ 1) andN03 : N(8.2
mg/1) with a small amount of organic N (2.0 mg/ 1).
The values given are typical values's and may differ
considerably depending upon the efficiency and re-
tention time of the treatment system. The application
of large amounts of secondary effluent to soils, (up to
120 inches/acre/year as proposed in some engineer-
ing feasibility studies) would however, result in rather
large annual applications of nitrogen.
The carbon:nitrogen ration (C:N) of secondary ef-
fluent will be less than 10:1 so net mineralization of
the small amount of organic nitrogen will occur. This
mineralized nitrogen as well as the NH4+-N initially
present in the effluent should be readily nitrified by
the chemosynthetic autotrophs Nitrosomonas and
Nitrobacter. The exceptions will be during winter
months in regions of low winter temperatures, in acid
forest soils or other soils with a low pH. It is also a
possibility that nitrification could be inhibited in ef-
fluent recycling systems employing forage grasses. An
inhibition of nitrification in grassland soils has been
frequently reported in the literature14.
The adsorption and utilization of this N03"by an
actively growing agronomic crop or by forest vegeta-
tion is extremely important for the success of effluent
recycling systems. Excess N03~above that required by
the growing plants will be subject to leaching and
could result in groundwater contamination. For this
reason rates of effluent application must be based on
the nitrogen needs of the vegetation taking into ac-
count that nitrogen which will be released by
mineralization of soil organic matter and any remain-
ing plant residues and the potential loss of N03~
through biological denitrification.
The significance of biological denitrification dur-
ing application of secondary effluent is difficult to
evaluate. Estimates of nitrogen losses through bio-
logical denitrification based on greenhouse and lysi-
meter studies have averaged 15 percent4. High mois-
ture conditions and intermittent soil saturation would
favor oxygen depletion and increased denitrification
if a readily available source of decomposable organic
matter is present. Although the effluent itself would
probably not supply sufficient organic matter, de-
composing crop residues or plant root exudates might
be adequate. As mentioned in the previous paragraph,
nitrification might be inhibited in the rhizosphere of
forage grasses. Since NOfis the starting point for bio-
logical denitrification such an inhibition would re-
strict nitrogen losses through denitrification. Because
of some of these unanswered questions studies of bio-
logical denitrification under field conditions is a pri-
mary research priority.
Anaerobically digested sewage sludge contains an
average of 2.4 percent nitrogen and activated sludge
averages 5.6 percent nitrogen, half of which is in the
ammonium form*. This quantity of nitrogen would
make both sludges low analysis fertilizers with re-
spect to nitrogen. However, the application of very
large quantities of sludge as often recommended for
sludge disposal on land (up to 100 tons/ acre) will re-
sult in extremely large additions of nitrogen. Limited
attempts have been made to estimate the mineraliza-
tion of organic nitrogen of anaerobically digested
-------
SOIL MICROBIOLOGICAL ASPECTS
87
sludge. Larson et «/'' utilized relative plant response
to estimate a six percent annual mineralization. Mil-
ler'" estimated that from 3.3 to 3.4 percent of the
sludge organic nitrogen appeared in the displaced
soil solution of a sandy soil after six months incu-
bation.
Nitrification of the added ammonium nitrogen or
mineralized organic nitrogen may be rapid or pro-
ceed only after a lag phase. Premi and Cornfield41
found that sludge amendments which supplied greater
than 102 Ibs of NH4+-N per acre inhibited nitrifica-
tion for up to eight weeks. The inhibition was thought
to be caused by an organic toxin. Miller40 found that
nitrification was inhibited for one month to two
months in sand and silt loam soils amended with 40
and 100 tons per acre of an anaerobically digested
sewage sludge. After this lag period nitrification was
rapid and extensive.
Large additions of sewage sludge to soils and ex-
tensive nitrification of ammonium and mineralized
nitrogen could result in nitrate accumulation above
that required by the crop. This nitrate would be sub-
ject to leaching and could result in deterioration of
groundwater quality. Lysimeter studies by Hinesly et
al1' have shown the accumulation and movement of
N03" through four feet of a silt loam soil amended
with from five to ten inches of liquid digested sewage
sludge. Nitrate nitrogen found in the leachate was
considerably higher than unfertilized check plots or
control plots receiving 200 Ibs of N per acre as com-
mercial fertilizer. The high risk of N03~ leaching has
prompted Hinesly et a/2' to propose that no more
than two inches (~ 6.6 tons/ acre) of an anaerobically
digested sewage sludge be added to supply the nitro-
gen needs of a non-leguminous crop. Even this rate
supplies over 600 Ibs of N per acre.
Biological or chemical denitrification could effec-
tively reduce the problem of excess nitrate but no de-
finitive studies have been conducted to estimate deni-
trification in sludge amended soils. High organic car-
bon wastes such as sewage sludge might provide both
the source of available carbon for the denitrifying
bacteria as well as an environment conducive to
zones of anaerobiosis.
CONCLUSIONS
It should be apparent from the previous discussion
that there are many unknowns in our understanding
of the important nitrogen reactions associated with
managing soils for recycling effluents and sludges.
Because of the environmental hazards associated with
nitrate leaching it seems advisable to recommend that
application rates for both effluent and sewage be
based on the amount of mineralized nitrogen re-
moved by the accompanying crop. The obvious prob-
lem associated with this decision is that we presently
have insufficient data to make good estimates of this
value.
Our research needs include estimates of nitrifica-
tion and denitrification in soils and the rhizosphere of
crops being irrigated with secondary effluent; data on
the rate of mineralization, nitrification, and denitrifi-
cation of sewage sludge nitrogen; and information on
the rate of and factors which influence NH, volatil-
ization during storage and application of sewage
sludge to soil. In the latter case any losses of NH^
would reduce the problem of excess N03~.
Phosphorus. Chemical fixation of orthophosphate
by Fe, Al, Ca, and clay minerals in soil and removal
by growing plants provide the primary mechanisms
for restricting the mobility of phosphorus applied
with effluents and sludges. Soil microorganisms in-
fluence the effectiveness of the soil for renovation by
mineralizing orthophosphorus from the more mobile
organic and condensed phosphates so that chemical
fixation can occur. The microbial synthesis of organ-
ic phosphorus and inorganic poly P in soils from or-
thophosphorus could result in greater mobility of P
through the soil profile. The significance of both of
these reactions needs further clarification. Buford
and Bremner" have not been able to substantiate that
claim that phosphine (PH3) is produced through the
microbial reduction of phosphate.
Sulfur. The microbial reaction of primary in-
terest in waste recycling is the oxidation of metal sul-
fides and H2S to S04= which is both mobile and avail-
able to plants. Organic sulfur of effluent and sludges
will be mineralized and oxidized toSO
-------
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
The microbial reactions of primary concern to the
solubility and mobility of inorganic ions involves one
or more of the following: oxidation-reduction, pre-
cipitation, solubilization, volatilization, production
of low molecular weight organic chelates, and the
formation and degradation of soil organic matter
capable of forming insoluble chelates. These reac-
tions were discussed in greater detail in a recent
paper4".
For a more thorough discussion of the soil reac-
tions of metal ions and other significant inorganic
ions the readers are referred to reviews by Ehrlich'*
and Leeper'2.
CONCLUSIONS
Considerable research emphasis is presently being
given to the reactions of heavy metals in soils and
their adsorption by plants. This emphasis has arisen
from a concern about the impact of heavy metals
from a variety of sources on our environment. Re-
newed interest in recycling of effluents and sludges
on land has been one area which has done much to
stimulate research on heavy metal ions.
The microbial reactions associated with waste re-
cycling in soils which require continued research em-
phasis are those involving the adsorption of high con-
centrations of metal ions by soil organic matter and
the solubilization of heavy metals by complexing with
low molecular microbial exometabolites. Both reac-
tions are extremely important to our understanding
of ion mobility and plant adsorption of metals in soil.
LITERATURE CITATIONS
1. Alexander, M. "Biodegradation Problems of
Molecular Recalcitrance and Microbial Fallibility."
Adv. Appl. MicrobioL, 7:35-80. 1965.
2. Alexander, M. "Persistence and Biological Re-
actions of Pesticides in Soils." Soil Sci. Soc. Amer.
Proc.. 29:1-7. 1965.
3. Alexander, M. Microhial Ecology. John Wiley
and Sons, Inc., New York. 1971.
4. Allison, F. E. "The Enigma of Soil Nitrogen
Balance Sheets." Adv. Agronomy, 7:213-250. 1955.
5. ARS, USDA, First Progress Report. "Incorpora-
tion of Sewage Sludge in Soil to Maximize Benefits
and Minimize Hazards to the Environment." Belts-
vine, Maryland. 1972.
6. Benarde, M. A., B. W. Doft, R. Horvath and L.
Shaulis. "Microbial Degradation of the Sulfonate of
Dodecyl Benzene Sulfonate." Appl. MicrobioL,
13:103-105. 1965.
7. Braids, O. C. "Environmental Pollution by Lead
and Other Metals," pp. 137. NSF Progress Report
from the Graduate College, University of Illinois,
May 1, 1971-April 30, 1972.
8. Burd, R. S. "A Study of Sludge Handling and
Disposal." Water Pollution Control Research Series
Publication No. WP-20-4, U.S. Department of the In-
terior. 1968.
9. Burford, J. R. and Bremner, J. M. "Is Phosphate
Reduced to Phosphine In Waterlogged Soils?" So/7
Bio/. Biochem.. 4:489-495. 1972.
10. Burges, A. and F. Row. Soil Biology. Academic
Press, New York. 1967.
11. Cooke, W. B. and P. W. Kabler. "Isolation of
Potentially Pathogenic Fungi from Polluted Water
and Sewage." Publ. tilth. Rep., 70:689-694. 1955.
12. Cook, W. B. "Fungi In Soils Over Which Di-
gested Sewage Sludge Has Been Spread." Mycopath.
Mycologia Applicata, 39:209-229. 1969.
13. Clark, F. E. "Bacteria In Soil." In Soil Biology,
A. Burges and F. Row (ed.). Academic Press, New
York. 1967.
14. Clark, F. E. and E. A. Paul. "The Microflora of
Grassland." Adv. Agronomy, 22:375-435. 1970.
15. CRREL Report. "Wastewater Management by
Disposal On Land." Corps of Engineers, U.S. Army,
Cold Regions Research and Engineering Laboratory,
Hanover, New Hampshire. 1972.
16. Dagley, S. "The Microbial Metabolism of
Phenolics." In Soil Bio-chemistry, Vol. 1, A. D.
McLaren and G. H. Peterson (ed.). Marcel Dekker,
Inc., New York. 1967.
17. Dunlop, S. G. "Survival of Pathogens and Re-
lated Disease Hazards." Proceedings of a Symposium
on Municipal Sewage Effluent for Irrigation,
Louisiana Polytechnic Institute, 1968.
18. Ehrlich, H. L. "Biogeochemistry of the Minor
Elements In Soil." In Soil Biochemistry, Vol. 2, A. D.
McLaren and J. Skujins (ed.). 1971.
19. Ellis, R., Jr. and R. S. Adams, Jr. "Contamina-
tion of Soils by Petroleum Hydrocarbons." Adv.
Agronomy, 13:197-216. 1961.
20. Engelbrecht, R. S. and D. H. Foster. "Micro-
bial Hazards In Disposing of Wastewater On Soil."
Proceedings of a Symposium on Recycling Treated
Municipal Wastewater and Sludge Through Forest
and Cropland, Penn State University, 1972. 1973.
21. Gibson, D. T. "Microbial Degradation of Aro-
matic Compounds." Science, 161:1093-1097. 1968.
22. Glathe, H. and A. A. M. Makawi. "Uber die
Wirkung von Klarschlanm auf Boden und Mikroor-
ganismen." Z. Pfl. Ernahr. Dung. 101:109-121. 1963.
23. Hinesly, T. D., O. C. Braids and J. E. Molina.
Agricultural Benefits and Environmental Changes Re-
sulting from the Use of Digested Sewage Sludge on
Field Crops. Report SW-30d, U.S. Environmental
Protection Agency.
24. Horvath, R. S. "Microbial Co-Metabolism and
the Degradation of Organic Compounds In Nature."
Bacterial. Rev., 136:146-155. 1972.
-------
SOIL MICROBIOLOGICAL ASPECTS
25. Huddleston, R. L. and R. C. Allred. "Surface
Active Agents: Biodegradability of Detergents." In
Soil Biochemistry, Vol. 1, A. D. McLaren and G. H.
Peterson (ed.), Marcel Dekker, Inc., New York. 1967.
26. Hunter, J. V. "Chemical and Biological Qual-
ity of Treated Sewage Effluent." Proceedings of a
Symposium on Recycling Treated Municipal Waste-
water and Sludge Through Forest and Cropland,
Penn State University, 1972. 1973.
27. Jenkinson, D. S. Studies on the Decomposition
of Plant Material In Soil II. "Partial Sterilization of
Soil and the Soil Biomass." J. Soil ScL, 17:280-302.
1966.
28. Kearney, P. C., D. D. Kaufman, and M. Alex-
ander. "Biochemistry of Herbicide Decomposition In
Soils." In So/7 Biochemistry, Vol. 1, A. D. McLaren
and G. H. Peterson (ed.), Marcel Dekker, Inc., New
York. 1967.
29. Krone, R. B. "The Movement of Disease Pro-
ducing Organisms Through Soils." Proceedings of a
Symposium on Municipal Sewage Effluent for Irriga-
tion, Louisiana Polytechnic Institute. 1968.
30. Lake Erie Report - A Plan for Water Pollution
Control. U.S. Dept. Interior, Fed. Water Poll. Cont.
Admin. 1968.
31. Larson, W. E., C. E. Clapp, and R. H. Dowdy.
Interim Report on The Agricultural Value of Sewage
Sludge, USDA, ARS and the Department of Soil Sci-
ence, University of Minnesota, St. Paul, Minn. 1972.
32. Leeper, G. W. Reactions of Heavy Metals with
Soils with Special Regard to Their Application In Sew-
age Wastes. Dept. of the Army, Corps of Engineers.
1972.
33. Lund, J. W. G. "Soil Algae." In Soil Biology, A.
Surges and F. Raw (ed.). Academic Press, New York.
1967.
34. Matsumura, F. and G. M. Boush. "Metabolism
of Insecticides by Microorganisms." In Soil Bio-
chemistry, Vol. 2, A. D. McLaren and J. Skujins (ed.),
Marcel Dekker, Inc., New York. 1971.
35. McCoy, J. H. "Sewage Pollution of Natural
Waters." In Microbial Aspects of Pollution, G. Sykes
and F. A. Skinner, (ed.), Academic Press, New York.
1971.
36. McGauhey, P. H. and R. G. Krone. "Soil Man-
tle as a Wastewater Treatment System." Engineering
Research Laboratory Report No. 67-11, University of
California, Berkeley. 1967.
37. McKenna, E. J. and R. E. Kallio. "The Biology
of Hydrocarbons." Ann. Rev. Microhiat.. 19:183-208.
1965.
38. McKinney, R. E., H. E. Langley and H. D.
Tomlinson. "Survival of Salmonella typhosa During
Anaerobic Digestion." Sewage and Industrial Wastes,
30:1469. 1958.
39. Miller, R. H. "Soil as a Biological Filter." Pro-
ceedings of a Symposium on Recycling Treated
Municipal Wastewater and Sludge Through Forest
and Cropland, Penn State University, 1972. 1973.
40. Miller, R. H. "The Microbiology of Sewage
Sludge Decomposition In Soil." EPA Report. 1973.
41. Molina, J. A. E., O. C. Braids and T. D.
Hinesly. "Observations On Bactericidal Properties of
Digested Sewage Sludge." Environ. Sci. Tech., 6:448-
450. 1972.
42. Painter, H. A., M. Viney, and A. Bywaters.
"Composition of Sewage and Sewage Effluents." Jour.
Inst. Sew. Purif., Pt. 4, 302. 1961.
43. Premi, P. R. and A. H. Cornfield. "Incubation
Study of Nitrification of Digested Sewage Sludge
Added to Soil." Soil Biol. Biochem., 1:1-4. 1969.
44. Rebhum, M. and J. Manka. "Classification of
Organics In Secondary Effluents." Environmental Sci.
& Tech., 5:606-609. 1971.
45. Rohde, G. "The Effects of Trace Elements On
the Exhaustion of Sewage Irrigated Land." Jour. Inst.
Sew. Purif., Pt. 6, 581-585. 1962.
46. Rudolfs, W., L. L. Falk and R. A. Ragotzkie.
"Literature Review of the Occurrence and Survival
of Enteric, Pathogenic and Relative Organisms In
Soil, Water, Sewage, Sludges and On Vegetation."
Sewage Ind. Waste, 22:1261-1281. 1950.
47. Stout, J. D. and O. W. Heal. "Protozoa." In Soil
Biology, A. Surges and F. Raw (ed.), Academic Press,
New York. 1967.
48. Thomas, R. E. and T. W. Bendixen. "Degrada-
tion of Wastewater Organics In Soil" J. Water Pollu-
tion Control Federation, 41:808-813. 1969.
49. Woodcock, D. "Metabolism of Fungicides and
Nematocides In Soils." In Soil Biochemistry, Vol. 2,
A. D. McLaren and J. Skujins (ed.), Marcel Dekker,
Inc., New York. 1971.
50. Van Donsel, D. J., E. E. Geldreich and N. A.
Clarke. "Seasonal Variations In Survival of Indicator
Bacteria In Soil and Their Contribution to Storm-
Water Pollution." Appl. Microhiol.. 15:1362-1370.
1967.
DISCUSSION
QUESTION: George Ward, George D. Ward &
Assoc., Portland, Oregon. I have a question to ask Dr.
Miller. I want to confirm a figure that I wrote down,
if it is correct on the bacteria biomass estimate. If it
was twenty-five hundred pounds per acre, and if it is,
I hope it is correct, because I want to take that home.
That is about the equivalent of the weight of a
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90
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
brahma bull running around on the ground and we
have land out there that will only support one cow
per four acres and if we can get one bull on the
ground—I am serious. And if this is what he didn't
say, what I would like him to help me with, is how
deep in the soil is that average bacteria biomass and
is that natural soil before we perhaps deployed them
and if we can maybe put this in by some deep plowing
at some rates I am not sure. But I don't think it would
cost too much to plow very deeply in soil and imbed
this instead of a centimeter, perhaps even three and
four feet. We might get a whole herd of brahma bulls
down there.
ANSWER: The figure that I have that is to the best
of my estimate is twenty-eight hundred pounds per
acre for about the surface fifteen centimeters, and
that is what the calculation was. Normally that is
where our microbial population is and its activity is
there. It decreases very rapidly both in numbers and
biomass as you go below that, and of course the
organisms are there because the organic matter is
there and these are natural systems, whether they be
grass land ecosystems or forest ecosystems, etc. Now,
the idea of deploying in certain circumstances would
probably be substantial except you still had to be
concerned about aeration down to that point. The
anaerobic system is going to have less cell numbers
per unit of carbon metabolized, it is going to
metabolize it less readily. If you can keep it aerated
with your deep plowing, you are going to increase
your organic matter content down to that depth by
incorporation. I think there are some problems of de-
ploying in certain soil systems. I know the soils peo-
ple at Ohio State are very skeptical about deep plow-
ing because it has been proposed as a method of im-
proving infiltration in one of the Corps of Engineer
plants in Ohio. We are skeptical because of the swell-
ing properties of some of the clay minerals which
basically would seal over the system again, and you
are not gaining anything. So, maybe we could put this
in the realm of an unknown that might need some
looking at some of the ideas.
-------
Inorganic
Reactions of
Sewage Wastes
with Soils
W. L. LINDSAY
Colorado State University
ABSTRACT
Sewage wastes decompose in soils to CO?, water,
residual soil organic matter, and inorganic constitu-
ents. The more soluble elements, which are generally
present as Na + , K+ , Ca?+, Mg?+,Cl~,SO4 2-, JVO.f,
and H) BO), either remain in solution or exchange
with ions on exchange sites on soil surfaces. Consider-
able technology is available on salt problems, ion ex-
change reactions, and movement of soluble salts
through soils that can be applied to the application of
sewage wastes to soils.
Another group of elements, which include Zn, Cd,
Pb, Cu, Ni, Cr, Hg, Mn, Co, P, As, Se, and Mo, form
compounds and reaction products of intermediate
solubility. Under many soil conditions these elements
are sufficiently soluble that they are taken up by
plants and cycled into the food chain of animals and
man. Recent developments in soil chemistry in the
areas of mineralogy, chemical equilibria, and metal
dictation offer many opportunities for critically and
quantitatively studying the solid phase-soil solution
equilibria. Such basic studies are needed to predict the
long-term fate of potentially toxic heavy metals and
other inorganic constituents that are added to soils by
the addition of sewage wastes. Eventually these ele-
ments will find a new home in the mineral matrix of
soils that will govern their availability to plants and
their movement in soils.
INTRODUCTION
Soil constitutes a natural and often convenient de-
pository for sewage wastes. When placed in the soil,
these materials decompose and undergo various
transformations. The organic components are decom-
posed largely to CO2, water, and residual soil organ-
ic matter. The soluble inorganic constituents are
leached away by drainage waters while insoluble
products accumulate in the soil to become a part of
the soil matrix. The question is asked "Will these in-
organic constituents that remain accumulate at suffi-
cient levels that they will present future hazards to
man as he attempts to use these soils for various pur-
poses in the future"?
Soils comprise a complex chemical matrix consist-
ing of numerous primary and secondary minerals in
various stages of weathering. The clay fraction con-
tains negatively charged colloides capable of adsorb-
ing and exchanging cations. Because of the amor-
phous nature and a lack of knowledge of many of the
solid phases that form in soil, too many scientists
consider the chemical reactions in soils solely as ad-
sorption reactions of the added constituents onto soil
surfaces. Recent advances in soil chemistry have
demonstrated that consideration must be given to the
specific ionic species in the soil solution and to many
dissolution and precipitation reactions that are in-
volved. The stability of metal complexes, metal che-
lates, and solid phase precipitates take on new mean-
ing when such considerations are given.
The scope of this paper is to show that the applica-
tion of basic chemical principles to soils can help
eliminate many needless experiments that otherwise
will be proposed to solve the problems of sewage
waste disposal in soils. Many related aspects of the
91
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92
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
sewage disposal problem are covered in different re-
ports of this workshop, therefore, this paper is restric-
ted to the chemical interactions of inorganic constitu-
ents in soils as they relate to soils as a depository for
sewage wastes.
Reactions of Sewage Wastes with Soil
The general nature of the reactions of sewage
wastes with soil is depicted graphically in Figure 1.
With time, the added wastes are broken down (reac-
tion 1) and the soluble constituents become part of
the soil solution. The released cations can exchange
with those already on exchange sites in the soil (reac-
tions 2 and 3). When the solubility of levels of ions in
solution exceed the solubility of solid phase com-
pounds and minerals, these compounds can precipi-
tate (reaction 4). When the soil solution becomes un-
dersaturated to any solid phase or mineral that is
present, that phase can dissolve (reaction 5). Ions in
the soil solution can be removed by plants or leached
from the soil by water moving through the soil profile
(reaction 6). Constituents are also ingested by micro-
organisms and incorporated into soil organic matter
(reactions 7 and 8). Gaseous constituents enter the
soil air and may escape from the soil (reaction 10), or
components of the soil air may react with those in the
soil solution and became part of the soil matrix (reac-
tion 9).
The soil solution is affected by all the reactions
that occur as constituents are either added to or taken
from it. The composition of the soil solution is ulti-
mately controlled by the solubility of various mineral
phases in soil. In many reactions the rates of precipi-
tation and dissolution are sufficiently slow that
kinetic as well as thermodynamic factors must be
considered.
So.'
A i r
Addition of
Sewage Waste
voo
^\x-
I1
^\ /£
Exchangeable Ions
and Surface
A dsorpt i on
Soil
1 Solution I
8 \ LA
Organic l"aMer V/t v^_
and \ '
M i c r o organ isms
I6
1 Removal by
Plants and
Leaching
s? Solid Phases
and
Minerals
Figure 1 Diagrammatical Representation of the Reactions of Sew-
age Wastes with Soil.
Classification of Inorganic
Sewage Constituents
Water is the most abundant inorganic constituent
in sewage. This compound is ubiquitous in soils and is
of little concern from a long-term pollution stand-
point.
Water percolates through soils via the normal
drainage channels carrying with it soluble salts,
mainly Na+, K+, Ca2+, Mg-7+, C1~ SO4 2-, NO,',
HCO "and H3 803. These soluble constituents often
cause problems. Under low rainfall conditions some
of the salts accumulate in the soil causing toxicities to
growing plants. The presence of high sodium leads to
deflocculation and poor physical properties of soils.
Under high rainfall or irrigation the soluble salts may
be leached through the soil and pollute the drainage
water or underground water supplies. The detriment-
al effects of soluble salts in sewage wastes can be
quite adequately accessed on the basis of past and
continuing investigations of salt problems in soils''.
Avoiding large scale deposition of soluble salts in
sewage systems may be desirable under certain cir-
cumstances.
The major exchangeable cations in soils comprise
Ca2+, Mg2+, Na+, K+, and acid soils also include A13+
and Ht Actually any cation added to the soil is cap-
able of exchanging with cations on the exchange. The
controlling factor governing the quantity of ions on
the exchange is the activity of those ions in solution.
Many metal cations present in sewage wastes form
precipitates and solid phases that limit their concen-
tration in the soil solution. Thus, only a small frac-
tion of those ions will remain on the exchange. The
less soluble cations will occupy the exchange only
until the precipitation reactions occur and reduce the
ionic activities in solution. These precipitation reac-
tions may continue for several weeks, and in some
cases for several years where heavy and continued
applications of sewage wastes have been made. We
must consider the solid phases that form in order to
understand the chemical transformations that occur
and the resulting equilibrium relationships.
Another group of the inorganic elements of con-
cern in sewage wastes form compounds of intermedi-
ate solubility. These include: Zn, Cd, Pb, Cu, Ni, Cr,
Hg, Mn, Co, P, As, Se and Mo. Considerable atten-
tion has been given to many of these elements and the
reactions they undergo in soils'21""2. Much of this
work, however, has been empirical and very few basic
chemical studies have been made to critically
examine the precipitation reactions that take place in
soils and how solubility is affected by specific para-
meters. The reaction products of these elements are
of concern because they remain sufficiently soluble
under various soil conditions that they are taken up
-------
INORGANIC REACTIONS
93
by plants and cycled into the food chain of animals
and man.
Another classification of inorganic constituents are
those that form relatively inert reaction products in
soils. These include cations of the higher oxidation
state such as Fe3* and Mn"+. As long as soils are well
oxidized these elements remain precipitated as highly
insoluble oxides. These elements, however, cannot be
considered permanently insoluble in soils, because
under reducing conditions they may become soluble
and mobile. It is not enough to consider an element
by itself. Its oxidation state, and complexation with
other ions and chelating agents determines whether a
given element will be classified in one catagory or
another. The intermediate valence state of Cr<4 is
stable in most soils and precipitates as insoluble
oxides.
The Form and Fate of Inorganic
Elements In Soils
Nitrogen
Nitrogen is a significant component in most sew-
age waste and often limits the loading rates of sewage
wastes on cultivated lands by the amount of nitrogen
a crop can tolerate. Decomposition of organic res-
idues releases NH4+that is soon oxidized NOs". Ni-
trate normally remains in solution as an anion and
moves with the soil solution. Under reducing condi-
tions NOf can be reduced to NO2~ (nitrate) and to N2
(nitrogen gas) and N2O (nitrous oxide). These gases
may escape to the atmosphere and constitute denitri-
fication losses from the soil. Under extremely reduc-
ing conditions these forms of nitrogen can also be
transformed into NH4+which behaves similarly to K+
in the soil. As oxidizing conditions return, however,
NH4^will again oxidize to NO.f.
Nitrogen may present several short range prob-
lems: too much sewage waste releases N that injures
crops and pollutes the groundwater. Nitrogen from
sewage wastes is not expected to produce any long-
term hazards in soils because it will not remain there
permanently. The slow release of N from the residual
organic matter can be considered a beneficial factor
in soil fertility.
Phosphates
Phosphates are an important component in most
sewage wastes, since P forms relatively insoluble re-
action products in soils. In acid soils Al and Fe phos-
phates are precipitated, while in soils of higher pH Ca
phosphates predominate6. These reaction products
are sufficiently insoluble that P is held in the upper
few centimeters of most soils and very little P moves
into the drainage water. High levels of P can some-
times cause nutrient imbalances such as P induced
Zn, Fe, Mn, and Mo deficiencies'*. The capacity of
soils to react with phosphates is almost infinite be-
cause of the large quantities of Fe, Al and Ca that are
present as potential reactants.
Polyphosphates have been used in detergents. The
polyphosphates can also precipitate, but in some
cases remain temporarily soluble. The formation of
insoluble Ca2 ?2 O7 2H2 O lowers the soluble phos-
phorus level to about 10-9 molar. With time, the poly-
phosphates will hydrolize in soils and be transformed
into the orthophosphates.
Additions of rather large quantities of P to soils as
may be done with large additions of sewage sludge
may lead to serious short-term problems. These in-
clude over fertilization with P, induced deficiencies,
and transport of P to drainage waters. Such additions
should, however, produce few long-term problems in
soils because of the tremendous capacity of soils to
supply Fe, Al, and Ca with which to react. The addi-
tion of sewage waste should be beneficial in supplying
a ready source of available phosphorus as this is one
of the major nutrient deficiencies throughout the
world.
Calcium, Magnesium, Potassium
and Sodium
These cations are involved in the exchange reac-
tions in soils, and to the extent that they can be re-
tained by exchange sites, they will be slowed down in
their passage through the soil. Eventually with con-
tinued leaching some of these cations will enter the
drainage water. Since these ions are abundantly pres-
ent under natural soil conditions, they are not expect-
ed to constitute great hazards. As mentioned earlier,
if large quantities of Na are added, it of course can
lead to saline and sodium-affected soils. Some of
these cations will also be incorporated in secondary
clay minerals and calcium carbonate. Again, these
are normal soil forming processes and would seem to
constitute no serious long-term pollution problems in
soils.
Zinc, Cadmium, Copper and Nickel
These divalent metal ions are normally not found
in soils in large quantities. Therefore, their inclusion
in sewage wastes may increase the total content of
these elements in soils significantly. Although these
cations can be held as exchangeable ions, only small
quantities will remain on the exchange as precipita-
tion reactions lower their level in solution below that
of the common exchangeable cations. The exact reac-
tion products that precipitate in soils with these ca-
tions are not known, but likely involve substitution in
-------
94
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
crystalline minerals and amorphous precipitates, as
well as forming possible discrete silicate compounds.
The activities of these metal cations are expected to
decrease with increase in soil pH. Recent studies4' in-
deed indicate that this happens. For zinc and copper
there is an approximate 100-fold decrease in activity
for each unit increase in soil pH. More attention
should be given to these metal cations and the long
range chemical reactions they undergo in soils. These
metals are potentially toxic to animals and plants and
may constitute future hazards if they are continually
added to soils. To the extent that these elements form
silicate minerals, it should be recognized that the
abundance of silica could provide the reactant to im-
mobilize rather large quantities of these metals with
time. Further investigations of the reactions of these
metal ions in soils should be thoroughly investigated
in order to predict the long-term fate of these metals
in soil environments and their incorporation into sec-
ondary minerals.
Iron and Manganese
These two metals are characterized in well-
oxidized soils as forming highly insoluble oxides and
hydroxides. The solubility of these hydroxides limit
the chemical activity of these metal ions to very low
levels. At low pH and under reducing conditions,
however, these metals can be solubilized and become
mobile in the soil as Fe2+ and Mn2+. Considerable
work has been done on concretions of iron and man-
ganese at the boundary lines where reducing oxidiz-
ing conditions change. Such conditions are respon-
sible for the formation of Fe and Mn pans, concre-
tions and deposits that often plug tile drains. Iron and
Mn are abundantly present in natural soils, so the ad-
dition of these elements in sewage wastes are not ex-
pected to cause any unusual problems. Recent in-
vestigations4 have given detailed chemical informa-
tion on the ionic species of Fe and Mn in the soil
solution and the effect of redox equilibria on these re-
lationships. Further studies are necessary in order to
pinpoint the redox conditions in soils that affect the
solubility relationships of Mn as it becomes toxic un-
der low pH conditions.
Chromium
Chromium is generally not, but can be, a signifi-
cant component in sewage wastes, especially from
certain industrial areas. In soils, however, Cr is gen-
erally oxidized or reduced to Cr^and precipitated as
an insoluble hydroxide. Further investigations should
be made under adverse conditions such as low pH
and changing redox potentials to access potential
hazards.
Lead
Considerable attention has been given to lead as an
environmental contaminant because of its wide use as
an additive for gasoline. Lead forms relatively insolu-
ble compounds in soils. Only recently has attention
been given to the solubility relationships of PbSO4,
Pb3(PO4)2 and PbCO3 as possible controlling
mechanisms in various soils4. These relationships
need further testing in order to clarify the mechanism
of lead reaction and fixation in soils. It would appear
that soils have a rather large capacity to immobilize
Pb. The long term accumulative effects of lead in
soils are uncertain at this point, but certainly need
more consideration. If PbCO^ is involved as a reac-
tion product, there is the possibility that soils of high
pH, upon becoming acidic, could release Pb at some
future time.
Mercury
Mercury forms insoluble compounds in the soil,
lowering the activity in solution such that very little
movement occurs and very little mercury is removed
by plants. The soil would appear to form a good sink
for this metal. Since the quantities of mercury added
in sewage wastes are relatively small, there appears to
be no great concern for this metal at the rates at
which it is applied to soils. Under low pH conditions
and with reduction, Hg may be mobilized. It can also
form soluble complexes that may be involved in its
mobility in soils under certain conditions. Further in-
vestigations are necessary in order to clarify the de-
tailed soil chemistry of this metal and its complexes
under various soil conditions.
Cobalt
Cobalt is somewhat similar to Ni in its chemical
reactions in soil. Since most sewage wastes contain
only small quantities, there has been no widespread
concern. As a component of sewage wastes cobalt in
soils appears to be strongly associated with Mn
oxides. Apparently, this metal cation substitutes for
Mn2+and is largely associated with Mn in soil. Most
of the problems with Co have been deficiencies in
grazing animals as Co is essential to ruminants. At the
present level of cobalt in most sewage waste there ap-
pears to be little long term concern with this element.
Molybdenum
The Mo content of sewage wastes is rather small.
However, consideration should be given to this metal.
It is present in well-aerated soils as the MoO4 2 . This
anion reacts with Fe3+ to form ferrimolybdate. This
compound is extremely insoluble under acid condi-
tions, but its solubility increases 100-fold for each
-------
INORGANIC REACTIONS
95
unit increase in pH4\ In soils below 7, Mo excesses
are not expected to occur. Unlike P, Ca molybdates
are highly soluble and provide no limit on the solu-
bility of Mo at high pH. Thus, in calcareous soils the
solubility of Mo is sufficiently available to plants as
to induce molybdenosis or Cu deficiency in grazing
animals. The problem of molybdenosis further made
worse by poor drainage and reducing conditions in
soils. Investigations are underway to determine possi-
ble limits of Mo in soils and water in order to avoid
molybdenosis in animals.
Selenium and Arsenic
The solubility relationships of Se in soils has been
studied11. Ferric selenites appear to be some of the
more probable reaction products. The solubility of
SeOi:+ is expected to increase with pH and to be af-
fected by changing redox potentials. Little is known
about the chemistry of As in soils. Further examina-
tion of these relationships are needed.
Chelation of Metal Ions In Soils
Most metal ions form soluble complexes and
chelates. These combinations increase the solubility
and mobility of metals in soils. Our understanding of
the role of metals in soils cannot be understood until
these complexes and chelates are given due consid-
eration. Metal ions compete for sites in chelates and
the overall chemical equilibrium relationships in soils
must be considered before the extent of complexation
can be estimates7". Recent advances in this field point
out the importance of metal chelation on metal ion
solubility and movement. Further advances in this
field will be possible once the solid phase solution
equilibrium of the various metal cations can be de-
fined and expressed quantitatively. Without a know-
ledge of these quantitative relationships the role of
metal ions in soils and their mobility and availability
to plants will remain as empirical observations on
isolated soils. Further advances in this area are possi-
ble and should be pursued.
RECOMMENDATIONS
The fate of inorganic constituents that are added
to soils in the form of sewage wastes present many in-
triguing challenges. The interaction of these inorgan-
ic constituents with the matrix of the soil involve
numerous chemical reactions. So far little attention
has been given to the precipitates and other solid
phases that provide solubility limits of many of these
inorganic elements. Recent advances in the field of
soil chemical equilibria offer many opportunities for
fruitful investigations in these areas. Recognizing the
reactions that occur and the limits of solubility that
are imposed by various reaction products, it will be
possible to predict the effects of changing soil condi-
tions on the solubility and mobility of these elements.
The chemistry of each of these elements is sufficiently
different that detailed investigations must be made for
each element. After the major reaction products of
these elemental constituents have been identified, it
will then be easier to understand the effects of pH, re-
dox equilibria, and the effect of accompanying ions of
their solubility. Many of the reaction products of
various elements in soils constitute complex solid
phases, including isomorphous substitutions and
changes from amorphous to more crystalline forms.
These facts often obscure solubility relationships,
especially when the specific ionic composition of the
soil solution is ignored.
With the advent of specific ion electrodes and the
availability of many stability constants for solid
phases and ion complexes and metal chelates, it
should be possible to make tremendous advances in
explaining the inorganic reactions that occur in soils
when waste materials are added to them. The long-
term effect of adding unnatural levels of various inor-
ganic constituents to soil will undoubtedly modify the
chemical composition of many of the precipitates and
the secondary clay minerals that will be present in
soils in years to come. An understanding of the con-
sequences of these additions will involve understand-
ing the detailed soil chemistry of the secondary
minerals that form in soils. Recent advances in the
areas of soil chemical equilibria provide useful guide-
lines for initiating detailed studies in these areas of
investigation. It is recommended that both practical
and basic studies be combined to examine the long-
term consequences of inorganic and heavy metal
additions to soils through waste disposal. The basic
study should help to illucidate the principles that are
involved and avoid unnecessary experimentation and
duplication of effort.
BIBLIOGRAPHY
1. Curry, M. G. and G. M. Gigliotti. "Cycling and
Control of Metals." Proceedings of an Environmental
Resources Conference, National Environmental Re-
search Center, Cincinnati, Ohio. 1973.
2. Lehman, G. S. and L. W. Wilson. "Trace Ele-
ment Removal from Sewage Effluent by Soil Filtra-
tion." Water Resources Research, 7:90-99. 1971.
3. Leeper, G. W. Reactions of Heavy Metals with
Soil with Special Regard To Their Application In Sew-
age Wastes. Dept. of Army Corps of Engineers Re-
port of Contract No. DACW73-73-C-0026. 1973.
4. Lindsay, W. L. Chemical Equilibria In Soils.
(Unpublished text.) 1973.
5. Lindsay, W. L. "Inorganic Phase Equilibria of
Micronutrients In Soils." Micronutrients In Agricul-
ture, (J. J. Mortvedt, P. M. Giordano, and W. L.
-------
96
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Lindsay, eds.)- Soil Sci. Soc. Amer., Madison, Wis-
consin, pp. 41-57. 1972.
6. Lindsay, W. L. and E. C. Moreno. "Phosphate
Phase Equilibria In Soils." Soil Sci. Soc. Am. Proc.,
24:177-182. 1960.
7. Lindsay, W. L. and W. A. Norvell. "Equilibrium
Relationships of Zn2+, Fe3+, Ca2+and H+with EDTA
and DTPA In Soils." Soil Sci. Soc. Am. Proc., 33:62-
68. 1969.
8. Norvell, W. A. "Equilibria of Metal Chelates In
Soils." Micronutrients In Agriculture, (J. J. Mortvedt,
P. M. Giordino, and W. L. Lindsay, eds.). Soil Sci.
Soc. Amer., Madison, Wisconsin, pp. 115-138. 1972.
9. Olsen, S. R. "Micronutrient Interactions."
Micronutrients In Agriculture, (J. J. Mortvedt, P. M.
Giordano, and W. L. Lindsay, eds.). Soil Sci. Soc.
Amer., Madison, Wisconsin, pp. 243-264. 1972.
10. Patterson, J. B. E. "Metal Toxicities Arising
from Industry." Trace Elements In Soils and Crops.
Min. Ag. Fish. Food Tech. Bull., 21:193-207. 1966.
11. Richards, L. A. (ed.). "Diagnosis and Improve-
ment of Saline and Alkali Soils." U.S.D.A. Agricul-
tural Handbook 60. 1954.
12. Webber, J. "Effects of Toxic Metals In Sewage
On Crops." Water Pollut. Control, 71:404-413. 1972.
13. Geering, H. R., E. E. Cary, L. H. P. Jones and
W. H. Allaway. "Solubility and Redox Criteria for
the Possible Forms of Selenium In Soils." Soil Sci.
Soc. Amer. Proc., 32:35-40. 1968.
-------
Organic*
F. E. BROADBENT
University of California
ABSTRACT
The organic components of sewage sludge are
partly undecomposed substances and partly microbial
cells and by-products synthesized during the treat-
ment process. Most substances in both categories are
readily biodegradable and undergo extensive decom-
position when incorporated in soils.
Part of the sludge applied to soil becomes part of
the soil humus after extensive modification, but most
is converted to simple inorganic compounds. Sludge
may contribute to soil improvement through its favor-
able effect on such soil properties as moisture holding
capacity, structural stability, and cation retention.
Organic Composition of Sludge
Soluble Organic Matter In Sewage
Most of the organic matter in domestic and in-
dustrial sewages which contributes to the five-day
BOD is soluble. For the most part this is readily con-
verted to carbon dioxide, water, and other inorganic
substances in aerobic treatment processes. Soluble
organics rarely would persist more than a few days at
most under conditions favorable for microbial activ-
ity. During the oxidation of this organic material
there is some synthesis of microbial cells due to the
rapid proliferation of bacteria and other microorgan-
isms in the presents of available substrate. The pro-
portion of soluble carbon which is converted to
microbial tissue varies somewhat with the environ-
mental conditions and with the composition of the
sewage3, but the synthetic efficiency is probably
lower than 50 percent in most cases. In anaerobic
systems the efficiency of conversion of soluble organ-
ics to bacterial cells is inherently low since oxidation
of the substrate does not proceed to completion and
the energy released per unit weight of substrate uti-
lized is much lower than under aerobic conditions.
Synthesized microbial cells become a part of the
insoluble organic material in the sewage being
treated, but are themselves readily subject to subse-
quent decomposition to simple inorganic substances
after death of the cells.
Insoluble Organic Matter
In Sewage
During the period of high biochemical oxygen
demand the decomposition of insoluble organic sub-
stances in sewage proceeds simultaneously with at-
tack on soluble substances but the rate is somewhat
slower than that of the soluble material and its con-
tribution to overall oxygen requirement is masked. In
domestic sewage and in waste from food processing
plants much of the solid material is cellulosic in
nature. Cellulose consists of bundles of long chains of
cellobiose units linked end to end to form a linear
polymer of high molecular weight and low solubility.
Many microorganisms in manure have the capacity
to hydrolyze cellulose chains to the simple sugar
units cellobiose and glucose, which in turn are read-
ily degraded further through normal metabolic path-
ways. The rate limiting step in this sequence is the
hydrolysis of the cellulose chain; consequently much
97
-------
98
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
of the cellulosic material in sewage ends up in sludge.
Hemicelluloses, which are mixed polymers of pen-
toses, hexoses, and uronic acid units, often linked
together in highly branched chains, as well as other
insoluble carbohydrates in food and human wastes
likewise contribute to sludge but to a lesser degree
than does cellulose.
Fats, waxes and oils which tend to float in sewage
processing may be partially incorporated into the
floe and settle in sludge. These are biodegradable
though not at a rapid rate.
The relative ease of biodegradation of a major part
of the sludge is emphasized by the term volatile solids
applied to it. These materials are not volatile in the
sense of having a high vapor pressure, but are readily
converted to gases, primarily CCh, through microbial
decomposition. Figure 1 shows the rate of disappear-
ance of sludge assuming first-order kinetics and a loss
rate of ten percent per day. In a batch process the
rate may be somewhat higher initially, but declines to
values well below the assumed value after a few days.
More information is needed on the nature and rela-
tive amounts of organic substances in sludges and on
the qualitative and quantitative changes which occur
during decomposition.
lOOq
HUMUS, 6 %/yeor
80
o
5 60
40
20
SLUDGE, 10 %/doy
10
DAYS
15
20
\ iiimc I Rate ot Decomposition ot Sludge Assuming First Ortici
kinetics .mil j I oss R.itc ot" Ten Percent Per Day
Composition of Bacterial Cells
Bacteria are composed primarily of protein and
much of the nitrogen in sludge is tied up in bacterial
cells. A frequently cited formula' of activated sludge
is CvHioNO}, corresponding to about nine percent
nitrogen in the organic component of the sludge. The
carbon: nitrogen ratio is six, which is much narrower
than is found in soil organic matter. Phosphorus and
sulfur are also present in organic combination in
microbial cells and in sludge, though not reflected in
the simplified empirical formula.
Bacterial by-products such as slime often produced
in copious quantities in sewage treatment are largely
of a polysaccharide nature. This material aids in
flocculation and in settling of solids and also contrib-
utes to the sludge. These polysaccharide materials
themselves are not resistant to microbial attack and
can be subsequently metabolized quite readily.
Soil Organic Matter and
the Microbial Population of Soils
Nature and Size of the Soil Population
The micropopulation of soils is ordinarily very
large, consisting of several diverse groups of organ-
isms which are predominantly aerobic in well drained
soils. The majority of forms are heterotrophic, deriv-
ing their energy material from the breakdown of
organic substances. Relative numbers of the principal
groups of microorganisms in surface soils are in-
dicated below.
Organisms Method
Bacteria
Number per gram
microscopic count 1 - 20 x 109
plate count 10s - 10"
Actinomycetes plate count
0.5 - 15 x
Mold fungi microscopic count 3 - 50 x 10ft
plate count .3 - 10 x 10s
Algae
Protozoa
dilution count
dilution count
.1 - 5 x 10*
10-1 - 105
In addition to these forms other micro and macro-
fauna are often present, such as nematodes and in-
sects.
As a result of the presence of this large and hetero-
geneous population of microorganisms there is in-
tense competition in the soil for available substrate,
which is normally in short supply because soil humus
degrades quite slowly. The rate of decomposition of
the organic fraction of soils usually is within the
range of two to ten percent per year. Another aspect
of the soil population which needs to be brought out
is that it has the capability of metabolizing a wide
variety of organic substances. Thus there are
organisms that can live on gasoline and motor oil,
-------
ORGANICS
fungi that can use both carbon and nitrogen in hydro-
gen cyanide, bacteria which decompose chlorinated
hydrocarbon pesticides. Organic substances ranging
from methane to molecules having molecular weights
in the millions are converted by the soil population to
simple inorganic products such as carbon dioxide,
water, nitrate, phosphate and sulfate in the soil.
In the light of the foregoing, the addition of sewage
sludge may be viewed as akin to throwing fuel on a
smoldering fire, which results in an increased rate of
combustion. Except for certain types of industrial
sludges, sewage sludge represents a substrate for the
soil population which is much higher on the scale of
availability than is the soil humus which normally
supports the soil population. However, quantitative
information on the kinetics of sludge decomposition
in or on soil is almost completely lacking. The influ-
ence of loading rates, methods of incorporation, ef-
fects of soil type, moisture tension, and soil tempera-
ture all need to be investigated. Obviously any in-
vestigation of environmental variables will require
use of sludge which has been well characterized in
terms of chemical composition.
Nature of Soil Humus
Many of the organic residues from which humus is
derived, primarily of plant and animal origin, are
similar to those in sewage. That is to say, these are
predominantly cellulosic but with hemicellulose,
lignin, chitin, protein, fats and waxes also represen-
ted. In extensive microbial decomposition the starting
materials are drastically altered, resulting in an end
product having properties unlike most of the plant
constituents. The carbohydrate materials, being com-
posed of sugar units, are extensively removed, leaving
those substances which are more resistant to micro-
bial attack. Humus most resembles lignin of the major
plant constituents in certain of its properties includ
ing resistance to biological attack. It has a chemical
structure based on aromatic nuclei with certain
typical substituent groupings such as carboxyl,
methoxyl, and phenolic hydroxyl.
Much of the chemistry of soil organic matter
remains to be elucidated, but certain properties are
known to be common to humus in soils everywhere
Among these is high molecular weight. All the evi
dence suggests that humus molecules are polydis-
perse, representing a broad range of molecular
weights from perhaps 103 to greater than 1O'
(Table 1).
The humic acid fraction, which is extractable with
alkali, probably has lower molecular weight than the
non-extractable humus. The average molecular
weight of soil humus may therefore be higher than the
highest values reported for humic acids.
The relative proportions of carbon, nitrogen,
sulfur, and phosphorus in humus are fairly constant
in soils of otherwise diverse properties, as shown in
Table 2 taken from Williams and Williams'.
Another important property of soil organic matter
is its high moisture retention capacity, which is often
on the order of several hundred percent on a volume
basis. This, of course, implies a great deal of swelling
during the wetting process. In general, organic matter
tends to improve the physical properties of soil. In-
creased permeability and greater stability of the soil
structure are usually associated with increasing the
organic matter level of soils. Application of sludge
may increase the humus content of soils which are
initially very low in this important constituent.
TABLE 1
Distribution of Molecular Weights, as Determined
by Gel Filtration, In Humic Acids
Extracted from Three Soils
Molecular wt.
<5000
5-10,000
IO-.SO.OOO
KXUXX) -200.000
Salinas
clay
16.6
38.5
242
0.0
0.0
% of humu IK id
Alkcn < lay
0.0
39.1
21.6
57
20.0
Stulen
'uly mutk
00
26.4
8.5
98
458
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100
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 2
Mean Ratios of C, N, S and Organic Phosphorus
In Four Groups of Soils
Group
Granite
Slate
Sandstone
Calcareous
C
169
147
130
113
N
10
10
10
10
S
1.45
1.42
1.37
1.27
P
2.41
2.37
2.97
1.32
Dramatic improvement in soil physical and chemical
properties may occur when sludge is applied on poor
soils, as for example strip mine soil. Documentation
of changes in soil properties as a result of sludge ap-
plication is another area where additional research is
needed.
Of particular importance in relation to sludge ap-
plication to soils is the high cation retention capacity
of soil organic matter, including the ability to form
stable complexes with metal ions such as lead, zinc,
cadmium and manganese. A comparison of the cation
retention capacity of soil organic matter with the
mineral fraction is given in Table 3.
Research is needed on the influence of sludge ap-
plications on cation exchange properties of soils. Of
particular importance is to determine the role of soil
organic matter in relation to the movement of poten-
tially toxic heavy metals.
The substantial buffering capacity of soil organic
matter which is associated with its high cation reten-
tion also has an important effect on soil chemical
properties which will bear further investigation in
relation to sludge disposal.
Biological Turnover of Soil
Organic Matter
It is difficult to estimate the rate of turnover of
soil organic matter since it is influenced by several
environmental variables. The decomposition rate
does not follow first order kinetics except for a brief
period following addition of a fresh carbon source.
Long term studies2 show carbon loss to be described
by equations of the form C = atm, where t = time, a is
a constant and m is a constant less than one. Nitrogen
is ordinarily conserved with respect to carbon in the
turnover process since the carbon: nitrogen ratios of
organic materials which normally are incorporated
in soil are of the order of 20 to 100 to 1. Since the
equilibrium carbon: nitrogen ratio in soil organic
matter usually is somewhere near ten, there is loss of
excess carbon as carbon dioxide but with nitrogen
being recycled many times until the ratio approaches
the equilibrium value. In the decomposition of
sludge, which may have carbon: nitrogen ratios less
than ten, substantial quantities of organic nitrogen
are mineralized and released as ammonia. Somewhat
slower mineralization rates were observed by King
TABLE 3
Cation Retention Capacities of Mineral
and Organic Fractions of Three Soils
Soil
O.M,
Cation exchange capacity
m.e./lOO g. soil
Dunkirk
Honeoye
Yates
9.75
6.57
5.70
Organic
fraction
18.8
13.3
9.4
Mineral
fraction
7.4
3.2
3.4
-------
ORGANICS
101
and Morris4 in their application of an anaerobic
treatment process sludge on Bermuda grass. In this
case decomposition was retarded somewhat by the
fact that the sludge was not incorporated in soil. In-
corporation is essential for rapid decomposition of
sludge because it helps maintain the moisture content
within the range favorable for microbial activity and
ensures the presence of a large and heterogeneous
soil population.
Virtually nothing is known of the nitrogen trans-
formations attendant to sludge applications on soils,
and these represent another area of needed research.
In the biological decomposition of humus there is
some synthesis of new cells. However, the physical
and chemical properties of humus do not closely re-
semble those of bacterial cells. The living component
of the soil organic fraction is relatively small at any
one time.
In the humification process, organic residues of
very diverse character are converted to material
which is biologically stable and which confers on the
soil many desirable physical and chemical properties.
The organic components of sewage sludges in the bio-
logically active soil environment will be largely de-
graded but a fraction of this material after extensive
modification will contribute to the organic fraction
of soils and as such become indistinguishable from
humus derived from other materials.
REFERENCES
1. Broadbent, F. E. "Basic Problems In Organic
Matter Transformations." Soil Sci. 79:107-114, 1955.
2. Corbet, A. S. "Studies on Tropical Soil Micro-
biology: 1." Soil Sci. 37:109-116, 1934.
3. Eckenfelder, W. W., Jr. and D. J. O'Connor.
Biological Waste Treatment, Pergamon Press, 1961,
New York.
4. King, L. D. and H. D. Morris. Land Disposal of
Liquid Sewage Sludge: I. "The Effect on Yield, in
Vivo Digestibility and Chemical Composition of
Coastal Bermuda Grass." J. Environ. Quality 1:325-
328, 1972.
5. Williams, C. H., E. G. Williams, and N. M.
Scott. "Carbon, Nitrogen, Sulphur, and Phosphorus
in Some Scottish Soils." Jour. Soil Sci. 11:334-346,
1960.
-------
Land Treatment
of Liquid Waste:
The Hydrologic
System*
HERMAN BOUWER
United States Department
of Agriculture
ABSTRACT
The main hydrologic factors to be considered in
the design and operation of land treatment systems are
(I) infiltration rates, (2) response of ground water to
infiltration, (3) effect of system design and manage-
ment on quality of renovated water, and (4) control of
underground spread of renovated water below the
water table. The last item is of special significance in
high-rate systems. Principles of controlling the spread
of renovated water are presented for deep and shallow
aquifers. Because the performance of a land treatment
system for liquid waste depends so much on the local
conditions of soil, climate, and hydrogeology, pilot
systems should precede any large-scale development.
INTRODUCTION
There are basically two types of systems for ap-
plying liquid waste (sewage effluent, processing plant
effluent, animal waste, etc.) to land: low-rate systems
and high-rate systems. With low-rate systems, about
one or two inches of wastewater may be applied per
week. With high-rate systems, the amounts may be in
the range of several feet to several yards per week.
With low-rate systems, the wastewater is usually ap-
plied with sprinklers, although surface irrigation
methods such as furrows or borders can be used if the
topography is favorable. With high-rate systems, the
wastewater is preferably applied with basins, using
water depths of several feet. On rolling land, furrows
or borders on the contour or sprinkler systems may
be used. Furrows or borders should be leveled to
avoid runoff, unless special precautions are taken for
storage or pump-back of the runoff. For both low-
rate and high-rate systems, the wastewater is applied
intermittently, rotating application or infiltration
periods with drying or resting periods. Application
schedules may range from several hours infiltration
each day or every few days (low-rate systems) to in-
filtration and drying periods of several weeks each
(high-rate systems).
The quality improvement of the wastewater as it
seeps through the soil and becomes "renovated
water" is usually greatest for low-rate systems. For
example, if secondary sewage effluent is applied at a
rate of one inch per week, the nitrogen load is of the
same order as the nitrogen uptake by an actively
growing crop, leaving little nitrogen in the renovated
water. A disadvantage of the low-rate systems is their
large land requirements, particularly if large waste
discharges are to be handled (at one inch per week,
260 acres are required to apply 1 mgd). Thus, it may
be advantageous to apply the wastewater at higher
rates, particularly if permeable soils with high infil-
tration rates are available. The resulting high-rate
systems have a greater impact on the groundwater,
however, to minimize this impact, high-rate systems
should be designed and managed to (a) produce a
renovated water of as good a quality as possible, and
(b) to restrict the spread of renovated water into the
groundwater basin.
The following hydrologic factors should be consid-
ered in the design of land treatment systems for liquid
waste:
103
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104
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
1. Infiltration rate.
2. Response of groundwater table to infiltration.
3. Effect of system design and management on
quality of renovated water.
4. Controlling underground spread of renovated
water below water table.
Infiltration Rate
Prediction
One of the key factors in the design of a land
treatment system is the long-term infiltration rate
that can be maintained. For sprinkler systems, this
rate gives an idea of the design application rate to
avoid surface runoff. For high-rate systems, this rate
indicates safe hydraulic loading rates and, hence, the
land requirements of the system.
The prediction of infiltration rates for disposal
fields is more difficult than the prediction of "nor-
mal" infiltration rates in watershed hydrology or irri-
gation design where rainfall or high-quality water is
used. This is because the wastewater contains sus-
pended solids that accumulate on the surface of the
soil and organic compounds that stimulate bacterial
action in and on the soil. Also, the cations in the
wastewater could have an unfavorable effect on soil
structure. These actions all decrease the infiltration
rate. The best way to determine the attainable in-
filtration rates for a land application system is
through field trials, using the actual wastewater and
application system to be employed (sprinklers,
furrows, or basins). These trials may also serve to
evaluate optimum amounts and frequencies of ap-
plication and to determine the effectiveness of
vegetation or other surface treatments of the disposal
field.
Sometimes, infiltration measurements with clean
water may be desirable to determine the "potential"
hydraulic loading rate of a field and to compare
fields as to their suitability for wastewater disposal.
The usual precautions should be taken to make sure
that the results are applicable to the entire field or
system. Thus, cylinder infiltrometers should be of
sufficiently large diameter to minimize the effect of
flow divergence on the measured infiltration rate. Al-
so, the infiltrometer (cylinder or sprinkler) should
cover a sufficient area to give realistic infiltration
rates in case restricting layers are present at some
depth in the soil profile. When a small infiltrometer is
used under those conditions, lateral flow will occur
in the groundwater mound that will be formed above
the restricting layer. The infiltration inside the cylin-
der will then be higher than the infiltration rate for a
large area, where lateral flow above the restricting
layer cannot occur.
Care should be taken when using infiltrometers on
sloping land with shallow soil. In such cases, the in-
filtration capacity of the field may be determined by
how much water can flow downhill as subsurface
runoff in the soil above the restricting layer. If water
is applied to a small area, as with an infiltrometer, all
the water that infiltrates may easily move downhill as
subsurface runoff. However, if larger areas are wet-
ted, the subsurface runoff may not be sufficient to
dispose of all the infiltrated water. In that case, the
soil becomes saturated to field surface and surface
runoff will occur. The actual infiltration rate is then
only a fraction of that indicated by a small infiltro-
meter.
Where restricting or impermeable layers are pres-
ent in the soil, it may be better to predict the poten-
tial infiltration rates from measurements of the hy-
draulic conductivity profile of the soil. Techniques
are available for field measurement of hydraulic con-
ductivity at different depths, above as well as below a
water table'. The final infiltration rate can then be
calculated by applying Darcy's equation to the one-
dimensional flow system. If the field is sloping and
the applied wastewater can only move away laterally
as subsurface runoff, the potential subsurface flow
can be computed. This value can then be divided by
the proposed width of the infiltration strip (on the
contour) to obtain an estimate of the safe application
rate.
The actual average long-term infiltration rate on
"hydraulic loading" for wastewater will be less than
the potential rates because of clogging by suspended
solids and biological action, and the need for drying
or resting periods. Also, the ionic composition of the
wastewater may cause deflocculation of the clay in
the soil and associated decrease in the hydraulic con-
ductivity. The relationship between potential and ac-
tual infiltration should be developed for various
wastes, soils, and climatic conditions, so that poten-
tial infiltration rates can be converted into design ap-
plication rates for wastewater disposal systems. For a
high-rate system west of Phoenix, Arizona2', for
example, secondary effluent is infiltrated from basins
at a water depth of one foot using schedules of two to
three weeks flooding alternated with 10 to 20 days
drying. The long-term hydraulic loading was found
to be about 23 percent of the potential infiltration
rate (i.e., 350 ft/yr versus 1,500 ft/yr). Similar data
should be obtained for other systems.
Soil Clogging
Land disposal of liquid waste invariably causes
clogging of the soil and resulting decline in infiltra-
tion rates. Clogging occurs on the surface, when sus-
pended solids do not move into the soil. Fine, suspen-
ded matter may actually move some distance into the
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THE HYDROLOGIC SYSTEM
105
soil, particularly in coarse textured soils. Bacteria
growing on the soil surface and in the soil pores may
also contribute to a permeability decrease because of
the space they occupy and the products they form
(including gases). High dissolved BOD-values may
cause serious clogging problems because of the bac-
terial activity they stimulate.
If clogging of the soil surface is caused by an inert
material, the impedance of the clogged layer can be
expected to increase linearly with the total solids
load, assuming that the clogged layer builds up uni-
formly. Since the clogged layer may become more
compact as the total solids load increases, however,
the impedance of the clogged layer may actually in-
crease more rapidly than the total solids load4. This
is particularly true if the hydraulic gradients at the
soil surface are relatively high. The clogged layer is
then subjected to a seepage force which causes com-
paction of this layer.
An unfavorable situation occurs where coarse
soil overlies finer soil. In that case, paniculate matter
may move through the coarse upper layer and settle
out on the finer soil layers further down. The
clogging caused by this is out of reach of the drying
influence of the sun or the mechanical influence of
spikes or disks of cultivators. Thus, it may take a very
long time of "resting" the system before the effects of
deep clogging on infiltration are alleviated. The same
is true for gravel layers or mulches. These may in-
crease infiltration rates initially, but their effec-
tiveness decreases with time. Once they are clogged
with solids, the infiltration rate is difficult to restore2.
The depth and extent of the clogged zone can be
evaluated with tensiometers installed in the soil at
different depths2. Soil clogging occurs where the hy-
draulic gradients increase with time. A quick way of
assessing where clogging occurs is to flood an area of
soil and measure the effect of water depth on infiltra-
tion rate;. Applying Darcy's equation to the infiltra-
tion system shows that if the infiltration rate increases
essentially linearly with the water depth, the clogged
layer is thin and at the surface of the soil. However, if
the infiltration rate is not as sensitive to water depth,
clogging takes place at greater depths or over a great-
er distance in the soil profile.
Surface clogging is the easiest to control or pre-
vent. Drying, harrowing, scraping, etc., are some of
the practices that have been effectively used to re-
duce the hydraulic impedance of the clogged layer.
Of course, the best way to control clogging is to pre-
vent it by minimizing the suspended soils content of
the wastewater, for example, by using settling basins
and, if needed, flocculants, filtration, or both. For
sewage effluent, the suspended solids content should
not be much greater than 10 nig/1 if high infiltration
rates are to be maintained4.
Where the wastewater is applied with sprinklers,
clogging should not be allowed to progress to the
point where runoff begins to occur. Runoff may also
be produced by high-intensity rainfall. Where this
can be expected, the suspended solids content of the
wastewater should be as low as possible to minimize
transport of accumulated solids from the field into
surface water. Level basins, furrows, or borders do
not pose a runoff hazard if they are designed to store
expected rainfall within the confines of their dikes
and ridges.
Scheduling Infiltration and Dry Periods
With continued application of wastewater,
clogging causes the infiltration rates to eventually be-
come so low that a drying or resting period is neces-
sary to restore the infiltration rates. Such drying will
allow dessication and decomposition of the clogging
material, which is usually effective to give complete
recovery of the infiltration rate:i. Occasionally,
some mechanical treatment such as scraping the sur-
face to remove accumulated solids, disking, or raking,
or an extra long dry period may be necessary.
If it is desirable to minimize the land area required
for the disposal system, the optimum combination of
infiltration and drying periods should be evaluated.
The application of wastewater should be stopped be-
fore the infiltration rates become too low, and it
should not be resumed until the infiltration rates have
made reasonable recovery. If the decrease in infiltra-
tion during application and the recovery in infiltra-
tion during drying are known, the combination of ap-
plication and resting periods yielding maximum long-
term infiltration or hydraulic loading can be evalu-
ated. Since the optimum combination of infiltration
and dry periods depends so much on the climate, the
type waste, and the soil characteristics, it can best be
evaluated by local experimentation.
Combinations used in actual practice include a few
hours infiltration every 24 hours (for processing
wastes), about 4 to 12 hours infiltration every week
(low-rate systems for sewage effluent), and infiltra-
tion and drying periods of several weeks each (high-
rate systems for sewage effluent).
Role of Vegetation
Vegetation is generally desirable for disposal
fields because it removes nutrients and other constit-
uents (metals, etc.) that entered the soil with the
wastewater. Vegetation may also be effective in
stimulating denitrification in the root zone causing
additional nitrogen removal from the soil2'.
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106
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Vegetated soils also dry to greater depths and to a
lower water content than non-vegetated soils during
the growing season. This will increase the oxygen dif-
fusion rate and allow more oxygen to penetrate deep-
er into the soil during drying.
Vegetative covers (Reed canary grass, bermuda-
grass, etc.) for the disposal fields are usually recom-
mended where wastewater is applied with sprinklers.
This protects the soil surface against the direct im-
pact of the drops, which could otherwise have an ad-
verse effect on the structure of the surface layer and,
consequently, on the infiltration rate. Vegetation also
intercepts some of the suspended solids, leaving less
solids to accumulate on the soil surface. New growth
of vegetation may break the continuity of impeding
layers on the soil surface, which in turn should have a
beneficial effect on the infiltration rate. Vegetation
also reduces soil erosion and the amount of solids
that may be washed off a disposal field with surface
runoff.
Where the wastewater is applied with basins, a dis-
advantage of vegetation is that it restricts the water
depth that can be used in the basin. This will in turn
result in lower infiltration rates, particularly where
the infiltration rate varies almost linearly with water
depth, due to surface clogging. On the other hand, a
shallow depth of water may be an advantage if it al-
lows enough light to penetrate to the bottom for algal
growth. When algae grow on the bottom, pieces of
the algal mat may actually float up when oxygen
bubbles become entrapped in the mat. Since suspen-
ded solids are carried up with the fragments of the al-
gal mat, this process "rejuvenates" the bottom of the
basin and has been observed to actually increase the
infiltration rates4. When vegetation is used in the
basins, flooding and drying periods may have to be
scheduled so as to allow the vegetation to develop
and survive. The resulting flooding and drying sched-
ules may not be the most desirable from a standpoint
of maximizing infiltration, maximizing nitrogen re-
moval by denitrification, or both. Thus, maximum in-
filtration is probably obtained with relatively deep,
non-vegetated basins, particularly if the wastewater is
relatively clear to allow sufficient light to penetrate
to the bottom.
Climate
Climate affects infiltration rates through the effect
of temperature on the viscosity of the wastewater and
through the effects of rain and temperature on the re-
covery of infiltration rates during drying. Since infil-
tration rates are inversely proportional to the viscos-
ity, a decrease in temperature will cause a decrease in
infiltration rate. A temperature drop from 80° F to
50°F, for example, will cause an infiltration reduc-
tion of about 34 percent to the change in viscosity.
Also, lower temperatures reduce the rate of drying of
the soil and of the clogged layer and the rate of de-
composition of organic clogging materials. Thus,
longer drying or resting periods will be required to
restore infiltration rates. Rainfall during resting
periods may also reduce the rate of infiltration re-
covery, particularly if the rain falls during the early
part of the resting period and solids have not yet
completely dried. Where the internal drainage of the
soil is a restricting factor, rain may have to be sub-
tracted from the hydraulic loading rate. This can be a
significant factor for low-rate systems on fine-tex-
tured or poorly drained soils.
Temperature has an effect on the biological and
chemical processes taking place in the soil. For
example, decomposition reaction rates may be re-
duced 50 percent for each 10°C drop in temperature.
Denitrification rates may be reduced more than nitri-
fication rates when temperatures drop below 10°C.
This could cause the system to remove less nitrogen
from the wastewater when temperatures are low.
Response of Water Table
to Infiltration
In the long run, wastewater can be applied to the
soil no faster than the internal drainage rate of the
soil. Where a restricting layer is present at some
depth and the infiltration rate is higher than the rate
of water movement through this layer, a perched
water table will form and rise above the restricting
layer. This water table will continue to rise until the
rate of water movement through the restricting layer
equals the infiltration rate. When the water table
reaches the soil surface, the infiltration rate becomes
equal to the rate of water movement through the re-
stricting layer. At this point a sharp decrease in in-
filtration may occur which can lead to surface runoff.
The effects of perching mounds or restricted subsur-
face runoff should be considered when selecting safe
hydraulic loading rates, as mentioned in the section
on predicting infiltration rates.
Rising water tables can also occur if the hydraulic
conductivity of the aquifer is fairly low or the aquifer
is relatively shallow and the groundwater moves es-
sentially in horizontal direction. Thus, an analysis of
the groundwater flow system below the disposal fields
should be made to make sure that the aquifer can
transmit the infiltrated water at a sufficient rate to
avoid build-up of groundwater mounds.
To ensure rapid drainage of the soil profile during
drying, which is necessary for effective oxygenation
of the soil, the groundwater mound should not be al-
lowed to rise closer to the soil surface than a distance
of about four feet, unless the mound rapidly recedes
after infiltration is stopped.
-------
THE HYDRO LOGIC SYSTEM
107
In soils with restricted drainage, such as shallow or
slowly permeable soils, an artificial drainage system
may be needed for rapid lowering of the water table
when drying is started. Drainage systems may also be
needed to prevent groundwater tables from rising to
the surface and restricting infiltration rates while
wastewater is being applied. Such drainage systems
can be designed in the same way as agricultural
drainage systems.
Effect of System Design and Management
on Quality of Renovated Water
The infiltration rate, the length of infiltration and
resting periods, and the way the wastewater is applied
(flooding or sprinkling) all have an effect on the qual-
ity improvement of the wastewater as it moves down
through the soil and becomes renovated water. The
lower the infiltration rate, the faster the quality of the
renovated water will improve in relation to distance
of percolation through soil. This can be an important
factor if the soil is fairly shallow or most of the qual-
ity improvement needs to be obtained in the first few
feet of travel. If deep soils are present or if the
renovated water goes through long times and distan-
ces of underground travel before it leaves the aquifer
(via springs, streams, lakes, drains, or wells), the ad-
ditional removal of phosphate, fluoride, metals,
organic carbon, and other constituents by the extra
underground travel may still produce renovated
water of acceptable quality.
The length of infiltration and drying or resting
periods may affect the form and concentration of the
nitrogen in the renovated water. If the nitrogen oc-
curs as nitrate in the wastewater and if organic car-
bon in the wastewater is sufficient for complete deni-
trification, denitrification can be obtained by apply-
ing the wastewater long enough to deplete the oxygen
in the upper soil layers. The organic carbon will then
be present in anaerobic zones in the soil where it is
available for the denitrifying bacteria. If such waste-
water is applied in frequent, small amounts, the soil
may be sufficiently aerobic to cause at least part of
the organic carbon to be oxidized by heterotrophic
aerobic bacteria, leaving less for denitrification and
hence causing more if not all of the nitrogen to re-
main as nitrate.
If the nitrogen is mainly in the ammonium form in
the wastewater and organic carbon in the wastewater
is not abundant, denitrification can be maximized by
continuing the application of wastewater long enough
to deplete the oxygen in the soil and to stop nitrifica-
tion of the ammonium''1'*'''. The ammonium will then
be adsorbed by the cation exchange complex in the
soil. Before this complex becomes saturated with am-
monium, a resting period should be started during
which the adsorbed ammonium can be nitrified. Part
of the nitrates thus formed can be denitrified as oxy-
gen is used up in the unsaturated zone. If such waste-
water were applied in frequent, small amounts, the
upper part of the soil would be mostly aerobic which
would yield essentially complete nitrification of the
ammonium and oxidation of the organic carbon. In
that case, essentially all the nitrogen in the waste-
water will be converted to nitrate with little or no
subseqent denitrification2'11''. If organic carbon in the
wastewater is abundant, however, enough may be left
for significant denitrification when the wastewater
moves into the deeper, anaerobic zones7.
The low oxygen levels in the soil, mentioned in the
previous paragraphs, are readily obtainable if the
wastewater is applied with basins or other flooding
techniques. If the wastewater is applied with sprin-
klers, the drainage of the soil between sprinkler revo-
lutions may draw sufficient oxygen into the soil to
maintain aerobic conditions in the upper portion of
the profile, particularly in rapidly draining soils. Un-
der those conditions, nitrogen removal by denitrifica-
tion may be difficult to achieve if the wastewater con-
tains relatively small amounts of organic carbon*.
Controlling Underground Spread
of Renovated Water
The quality of the renovated water will usually be
inferior to that of the native groundwater, even when
the land treatment system is managed to obtain the
best quality renovated water achievable. Where there
is a concentrated source of renovated water entering
the groundwater, such as with high-rate systems, pro-
visions may be needed to restrict the spread of reno-
vated water into the groundwater basin. This can be
accomplished by taking the renovated water out of
the aquifer at some distance from where it entered the
groundwater, as happens naturally when the ground-
water drains to a stream or a lake (Figure 1). If the
renovated water does not leave the aquifer in a na-
tural manner, it should be collected by drains (for
WASTE WATER
'APPLICATION
IMPERMEABLE
Figure 1- Renovated Wastewater Draining Naturally Into Surface
Water
-------
108
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
shallow aquifers) or wells (for deep aquifers) to limit
its spread into the aquifer. After collection (and addi-
tional treatment if necessary), the renovated water
may be used for irrigation, recreation (including
lakes), industrial, and perhaps municipal purposes, or
it may be discharged into surface water. With these
systems, a portion of the aquifer is essentially used as
a natural filter.
The proper distance between the point where the
wastewater enters the soil and where it leaves the
aquifer as renovated water depends on the type
wastewater, the desired quality of the renovated
water, and the nature of the soil and aquifer mater-
ials. For granular soils and aquifers, underground
travel distances of several hundred feet and under-
ground detention times of several weeks may be suffi-
cient to yield a renovated sewage effluent of suitable
quality. The more time and distance of underground
travel are allowed, the better the quality of the reno-
vated water will be, at least to a certain limit. Most of
the quality improvement, however, takes place in the
first few feet of the soil profile.
Deep Aquifers
When the aquifer is unconfined and relatively
deep, a "closed" wastewater renovation system can
be obtained by concentrating the areas where the
wastewater is applied to the land in two parallel "in-
filtration strips" (Figure 2). The renovated water can
then be pumped from wells midway between the
strips. Other possibilities are a single infiltration strip
with wells on both sides, or a central infiltration area
surrounded by a ring of wells (Figure 3). The wells in
the two systems of Figure 3 will pump a mixture of
native groundwater and renovated wastewater. This
WASTE WATER
APPLICATION!
IMPERMEABLE
LAYER
may be desirable if the use of the pumped water re-
quires dilution of the renovated water anyway. How-
ever, if recovery of renovated water is the main ob-
jective of the wells, the additional native groundwater
increases the pumping costs and constitutes an extra
draft on the native groundwater.
Figure 2- Schematic of Two Parallel Strips (Hatched Area) for Ap-
plying Wastewater and Wells Midway Between the Strips for Pump-
ing Renovated Water from Deep Aquifer.
Figure 3: Long Infiltration Strips (Hatched Area) with Wells on
Both Sides (Left) and Circular Infiltration Area Surrounded by
Wells (Right).
The design and operation of a wastewater renova-
tion system consisting of two parallel infiltration
strips and wells midway between the strips (Figure 2),
should be based on the following three criteria:
1. The water table below the infiltration strips
should not rise to field surface where it can restrict
the infiltration rates. Preferably the water table
should not come closer to field surface than a dis-
tance of about four feet. This enables rapid drain-
age of the soil profile, and hence entry of oxygen,
when infiltration periods are rotated with dry or
resting periods.
2. All wastewater that has infiltrated should be
pumped as renovated water from the wells. No ren-
ovated water should move into the aquifer outside
the system of infiltration areas and wells.
3. The renovated water should have had the proper
time and distance of underground travel when it
reaches the wells.
In order to investigate whether a certain design
meets these three criteria, the underground flow sys-
tem must be predicted. This will also yield an esti-
mate of the pumping lift in the wells.
The prediction of the underground flow system for
renovation systems as in Figure 2 requires knowledge
of the rate of entry of wastewater into the soil and of
the hydraulic properties of the aquifer. The infiltra-
tion rates may be evaluated by local experimentation
as previously explained. The main hydraulic property
to be evaluated for the aquifer is the effective trans-
missibility for groundwater recharge, which will gov-
ern the flow system under and near the infiltration
strips.
The effective transmissibiliry for groundwater re-
charge is less than the total transmissibility of the
aquifer, particularly for relatively deep, unconfined
-------
THE HYDROLOGIC SYSTEM
109
aquifers, because recharge flow systems are charac-
terized by an upper, active zone, and a lower, passive
zone1*'"'. The effective transmissibility for recharge
depends on the width of the infiltration strip. It in-
creases essentially linearly with that width until it has
become equal to the total transmissibility of the aqui-
fer. Once the underground flow has become mainly
horizontal, such as in the vicinity of the wells (Figure
2), the total transmissibility of the aquifer can be used
to analyze the rest of the flow system'". If the wells
do not completely penetrate the aquifer, the appro-
priate correction factors should be applied to the
total transmissibility.
A good way to evaluate the effective transmissibil-
ity of an aquifer for groundwater recharge is from the
response of groundwater levels to infiltration, as may
be determined in an experimental recharge project'".
This was done for the Flushing Meadows Project in
the Salt River bed, west of Phoenix, Arizona, where
renovation of secondary sewage effluent by land ap-
plication is studied with six parallel recharge basins
covering a block of 220 x 700 feet2'1. Two observa-
tion wells, one 30 feet deep and the other 100 feet
deep, were installed in the center of this block. The
response of the water levels in these wells to infiltra-
tion was simulated on an electrical analog, which
then yielded the hydraulic conductivity of the aquifer
in vertical and horizontal directions'". The resulting
values agreed with data obtained from direct permea-
bility measurements on seven observation wells in the
project'".
Since the directional permeability components of
the aquifer were known, the theoretical shape of the
groundwater mound could be evaluated by electrical
analog"'. The Dupuit-Forchheimer theory was then
applied to this mound to obtain the effective trans-
missibility of the aquifer for the recharge flow system,
which was only 12 percent of the total transmissibil-
ity'". This effective transmissibility, corrected for the
width of the infiltration strip, was used in analog
analyses of flow systems for the prototype system (Fi-
gure 2) to predict the shape of the water table and to
construct a network of streamlines and equipoten-
tials" . When a certain porosity of the aquifer mater-
ial was assumed, the macroscopic velocities of the
water from one equipotential to the next could be de-
termined for each stream tube, which in turn yielded
estimates of the total underground travel time of the
renovated water'". The procedure was applied to
various designs so that the optimum layout of infiltra-
tion areas and wells could be selected'". Similar pro-
cedures can be applied to the design of other high-
rate, closed wastewater renovation systems.
Shallow Aquifers
If the water table and the impermeable layer arc
relatively close to field surface, wells may not be ef-
fective and the renovated water is better collected by
open or closed drains. The system could consist of
two parellel strips where the wastewater is applied to
the soil with a drain midway between the strips (Fig-
ure 4A), or of a series of infiltration strips and
drains (Figure 4B). Since infiltration periods are
usually rotated with drying periods, short under-
ground travel distances and detention times can be
avoided in the system of Figure 4B by closing the
drains below the strips receiving wastewater and col-
lecting the renovated water with the drains below the
drying strips. These drains will be closed, and the
other drains opened, when infiltration and drying
periods are rotated (Figure 4C).
The water table in the systems of Figure 4 should
preferably not rise so high that it reaches the soil sur-
face in the infiltration areas and reduces the infiltra-
tion rates. The shape of the water table in these sys-
tems can be calculated with drainage theory1'. Using
the Dupuit-Forchheimer assumption of horizontal
flow and assuming a uniform infiltration rate, the fol-
lowing equation can be derived for the flow system
between the infiltration area and the drain (Figure 5).
Hc=Hd + f K. (W +2L)
where
Hc = height of water table above impermeable layer
at outer edge of infiltration strip for sys-
tems as in Figure 4A and at center of infiltra-
tion strip for systems as in Figure 4B.
Hd = height of water table above impermeable layer
at drain
I =infiltration rate (length/time)
W = width of infiltration strip for systems as in
Figure 4A and one-half width of strip for
systems as in Figure 4B.
K =hydraulic conductivity of soil (length/ time)
L = distance between edge of infiltration strip and
drain
The term W refers to the longest horizontal dis-
tance of travel for the water beneath the infiltration
strip. If the drain is running free, Hc) will be equal to
the height of the center of the drain above the imper-
meable layer. However, if a back-pressure is main-
tained in the drain (which is sometimes done to ex-
clude air and to avoid deposits of iron or manganese
oxides in the drain), Hd is the height of the drain
above the impermeable layer, plus the back-pressure
head.
Knowing Hd, I, and K, the value of Hc can be cal-
culated for various combinations of W and L. Thus,
-------
110
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
/////////ss///s /////s//////
IMPERMEABLE
A
O DRAIN OPEN
P5 DRAIN CLOSED
IMPERMEABLE
B
111
^777^/777777/77/7/77/77777/77/77777777777/7/7/7777
IMPERMEABLE
c
Figure 4' Two Parallel Infiltration Strips with Drain Midway Between Strips (A) and Continuous System of Infiltration Strips and Drains with
Alternate Infiltration and Drying (B and C).
t—>X
IMPERMEABLE
Figure 5 Geometry and Symbols for Parallel Infiltration Strip and
Drain
the optimum combination of W and L whereby Hc
does not exceed a preselected value can be evaluated.
If the wastewater is applied to the soil with infiltra-
tion basins and the groundwater table is so high that
it coincides with the water surface in the basins, the
equation can be used to calculate the average infiltra-
tion rate in the basin. To obtain sufficient time and
discharge of underground travel for the water in the
systems of Figure 4B, certain modifications may have
to be incorporated.
The equation applies to relatively shallow systems.
Where the impermeable layer is at sufficient depth to
render the horizontal-flow theory invalid, equivalent
depths of the impermeable layer should be used as is
done in the design of agricultural drainage systems'2.
Pilot Projects
The performance of a low-rate or high-rate system
for applying wastewater to soil is very much depen-
dent on the local conditions of climate, topography,
soil, and hydrogeology. Unless similar projects al-
ready exist in the area, it is very desirable to experi-
ment with a small pilot project before going into any
large-scale development. The results from the experi-
mental project can then be used as input information
for the design and management of the operational
system. Experimentation with a pilot project could
well save a lot of disappointment and money later on.
Finally, the best designed system for applying waste-
water to land will still be a failure if it is not properly
managed.
SUMMARY AND RESEARCH
RECOMMENDATIONS
The hydrologic aspects of systems for applying
liquid waste to land are basically covered by irriga-
tion and drainage theory. Factors to be considered
include (a) the design application or infiltration rates
in relation to the hydraulic acceptance of the soil, the
desired quality improvement of the water, and the in-
tended longevity of the system, (b) the most appro-
priate system for applying the wastewater, and (c) the
-------
THE HYDROLOGIC SYSTEM
111
groundwater management below the receiving fields.
While most irrigation and drainage principles are
generally known, there is still need for additional re-
search on many of these aspects. Because the per-
formance of a land treatment system depends so
much on the local conditions of soil, climate, and
groundwater geology, local research and pilot sys-
tems should usually precede large-scale develop-
ments.
Additional research is needed to determine the ef-
fect of the application system itself on the hydraulic
loading rate and the quality improvement of the
wastewater as it moves through the soil. The loading
rates and oxygen regimes for flooded and sprinkled
soils are not the same, for example, and this may in-
fluence denitrification, immobilization of heavy
metals, and other reactions. More research is needed
on the optimum treatment of the wastewater before it
is applied to the land. If the water is to be reused, the
soil filtration process may not yield renovated water
of sufficient quality at high loading rates. In that case,
studies should be made to determine the optimum
combination of treatment of the water before and af-
ter it has moved through the soil.
REFERENCES
1. Bouwer, Herman. "Planning and Interpreting
Soil Permeability Measurements." Jour. Irrig. and
Drain. Div., Amer. Soc. Civil Engin. Proc., 95 (IR3):
391-402. 1969.
2. Bouwer, Herman, Rice, R. C, Escarcega, E. D.,
and Riggs, M. S. "Renovating Secondary Sewage by
Groundwater Recharge with Infiltration Basins."
U.S. Environmental Protection Agency, Water Pollu-
tion Control Research Series, Project No. 16060
DRV. (101 pp.) Supt. of Documents, U.S. Govt. Print.
Office, Washington, D.C. 20242.
3. Bouwer, Herman. "Renovating Secondary Efflu-
ent by Groundwater Recharge with Infiltration
Basins." Proc., Symp. on Recycling Treated Munici-
pal Wastewater and Sludge Through Forest and
Cropland, Penn. State Univ., August 1972. (In press).
4. Rice, Robert C. "Soil Clogging During Infiltra-
tion with Secondary Sewage Effluent." Jour. Water
Poliut. Contr. Fed. (In press).
5. Lance, J. C., and Whisler, F. D. "Nitrogen
Balance In Soil Columns Intermittently Flooded with
Sewage Water." Jour. Environ. Quality 1 (2): 180-186.
1972.
6. Lance, J. C., Whisler, F. D., and Bouwer, H.
"Oxygen Utilization In Soils Flooded with Sewage
Water." Jour. Environ. Quality. (In press).
7. Erickson, A. E., Tiedje, J. M., Ellis, B. G., and
Hansen, C. M. "A Barriered Landscape Water Reno-
vation System for Removing Phosphate and Nitrogen
from Liquid Feedlot Waste." Proc. Internatl. Symp.
on Livestock Wastes, Ohio State Univ., Columbus.
Published by Amer. Soc. Agr. Engin. 232-234. 1971.
8. Smith, T. P. "Actual Spray Field Operations."
Proc. Land Spreading Conf., East Central Florida
Regional Planning Council, Orlando, Fla. Paper No.
8. 1971.
9. Bouwer, Herman. "Limitation of the Dupuit-
Forchheimer Assumption In Recharge and Seepage."
Amer. Soc. Agr. Engin. Trans. 8:512-515. 1965.
10. Bouwer, Herman, "Groundwater Recharge De-
sign for Renovating Wastewater." Jour. Sanitary Eng.
Div., Amer. Soc. Civil Engin. Proc. 96 (SA1): 59-74.
1970.
11. Bouwer, Herman. "Design and Operation of
Land Treatment Systems for Minimum Contamina-
tion of Groundwater." Proc. Internatl. Symp. on Un-
derground Waste Management and Artificial Re-
charge, New Orleans, La., Sept. 1973. Sponsored by
Amer. Assoc. Petrol. Geol., U.S. Geol. Survey, and
Internatl. Assoc. Hydrol. Sci.
12. Bouwer, Herman, and Van Schilfgaarde, J.
"Simplified Prediction Method for the Fall of the
Water Table In Drained Land." Amer. Soc. Agr.
Engin. Trans. 6:288-291. 1963.
-------
Land
Resources
K. W. FLACH
Soil Conservation Service
ABSTRACT
Soil, climatic, geologic, and institutional factors
have to be considered in selecting sites for waste dis-
posal on land. Runoff, erosion, permeability, infiltra-
tion capacity, and available water holding capacity
urc important soil properties that have to be con-
sidered. The balance and distribution of precipitation
and evapo-transpimtion are important climatic con-
siderations, and lithology, jointing, and groundwater
relationships are important geologic factors Avail-
ability of public land and farm size must also be taken
into account. Soil surveys conducted by the Soil Con-
servation Service of the United States Department of
Agriculture and its cooperators can be used for
evaluating the feasibility of disposal systems and for
locating sites. Soils suitable for waste disposal are
available near most metropolitan areas but the eco-
logical, economic, and institutional factors are more
favorable in the arid western United States.
INTRODUCTION
Disposal on land may substitute for secondary and
tertiary treatment of liquid wastes and serve as the
means of processing the residues (sludge) of second-
ary and tertiary biological or chemical waste proc-
essing systems. In either case the waste must be de-
stroyed or absorbed in the soil and any effluent must
not contribute to the degradation of our water and air
resources. Land-based disposal systems must be close
to sources of effluents and they must be institutional-
ly acceptable. Finally, any system must be capable of
being operational long enough to amortize its cost.
In this paper the land-related requirements of such
a system, soil, climate, geology, institutional factors,
and the availability of land meeting these require-
ments are discussed.
Soil Factors
Soil can fulfill many functions in a waste disposal
system. It can provide a medium in which organic
compounds can be oxidized and the BOD dissipated.
It can provide a combination of oxidizing and reduc-
ing environments in which nitrogenous compounds
are first oxidized and then reduced to nitrogen gas.
The soil may absorb and inactivate inorganic com-
pounds such as phosphates and some heavy metals
and it may serve as a filter for pathogens and as a
medium for oxidizing them. Water may move through
the soil, be filtered, and be used to recharge the
groundwater supply. If a crop is grown on the soil,
the water may be largely evaporated and very little
or no water may percolate or run off. Soluble salts
are either precipitated in the soil or are taken up by
the plants and recycled if the crop is used for feed.
All soil has some of these capabilities. But deep
soils that have a large total surface area and contain
much clay and organic matter absorb and filter
wastes more effectively than shallow, sandy soils. But
soil must also have the ability to accept the wastes.
Liquid wastes must be able to infiltrate and percolate
the soil, and vehicles delivering sludge or solid waste
must be able to enter the disposal site during all times
of the year. These requirements are best met by rela-
tively coarse, sandy soil that, unfortunately, has only
113
-------
114
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
limited capability to adsorb and filter. Hence, the re-
quirements for soil as a medium for waste disposal
are conflicting and even the best site, found after a
long search, will be a compromise.
Soil surveys, prepared by the Soil Conservation
Service of the United States Department of Agricul-
ture in cooperation with agricultural experiment sta-
tions and units of local government, can be of help in
this search. Soil scientists making soil surveys not
only make maps but they also evaluate the usefulness
of individual soils for specific purposes. Criteria for
evaluating soils for many uses have been established,
and ratings of individual soils for these uses are in-
cluded in modern published soil surveys.
A guide for assessing the suitability of kinds of soil
as media for disposal of wastes has been prepared and
is being tested. Although this guide is aimed primarily
at farm and food processing wastes, it is also relevant
to municipal and some industrial disposal systems.
Slightly modified summary tables from this guide are
reproduced in Tables 1 and 2. Six soil proper-
ties—permeability of the most limiting subsoil layer,
infiltration rate, soil drainage, runoff, flooding, and
available water holding capacity—are used to rate
kinds of soil as having slight, moderate, or severe
limitations for use for waste disposal. Most of these
criteria are self-explanatory except for available wa-
ter holding capacity. This criterion, measured in
TABLE 1
Soil Limitations for Accepting
Nontoxic Biodegradable Liquid Waste1
Item!
Permeability of the
most restricting sub-
soil horizon to 60
inches
Slight
Moderately rapid
and moderate
0.6-6.0 in./ hr.
Degree of soil limitation
Moderate
Rapid and mod-
erately slow
6-20 and 0.2-
0.6 in./ hr.
Severe
Very rapid,
slow, and very
slow >20 and
< 0.2 in./hr.
Infiltration
Soil drainage
Runoff
Flooding
Very rapid,
rapid, moder-
ately rapid,
and moderate
> 0.6 in./ hr.
Well drained
and moderately
well drained
None, very slow,
and slow
Soil not
flooded during
any part of the
year
Moderately
slow
0.2-0.6
in./ hr.
Somewhat ex-
cessively
drained and
somewhat
poorly drained
Medium
Soil flooded
only during
nongrowing
season
Slow and very
slow
< 0.2 in./hr.
Excessively
drained, poorly
drained, and
very poorly
drained
Rapid and very
rapid
Soil flooded
during growing
season
Available
water T > 7.8 inches 3-7.8 inches < 3 inches
capacity
to 60 inches
or to a P4 > 3 inches < 3 inches
limiting
layer
'Modified from a draft guide for use in the Soil Conservation Service, LJSDA.
!For definitions see the Sail Survey Manual, U.S. Department of Agriculture Handbook No. 18, 1951.
'Temporary Installation.
'Permanent Installation.
-------
LAND RESOURCES
115
TABLE 2
Soil Limitations for Accepting
Nontoxic Biodegradable Sludges and Solids'
Moih'ruh'
.Sci'c/c
Permeability of the
most restricting
layer above
60 inches
Soil drainage
Runoff
Moderately rapid
and nxxlcratc
0.6-6.0 in / hr
Well drained
and moderately
well drained
None, very slow,
and slow
Soil not flooded during
.my par! ol the year
Rapid and moder-
ately slow
6-20 and 0.2-
06 in./hr
Somewhat exces-
sively drained
and somewhat
pcxirly drained
Medium
Very rapid, slow,
and very slow
> 20 and
< 0 2 in / hr.
Excessively
drained, prly
drained, and very
poorly drained
Rapid and very
rapid
Soil flded
during some part
of the year
> 7 8 inches
3-7.8 inches
< 3 inches
Available water
capacity from
0 to 60 inches or
to a limiting
layer
'Modified from a draft guide for use in the Soil Conservation Service, USDA
'For definitions see the &>il Survey Manual, U.S. Department of Agriculture Handbook No. 18, 1951.
inches for the whole soil, is the depth of the layer of
water that would be formed if all water in the soil
that can be used by plants were concentrated at the
soil surface. The equivalent volume measure would
be the acre-inch (27,000 gallons) or the acre-foot
(326,000 gallons). Available water holding capacity
used in this way integrates the effects of soil texture
and depth and is a convenient measure for effective
soil volume. It should be noted that in this guide se-
vere limitations reflect limiting capacity of the soil to
accept wastes and limited capability of the soil to
render wastes harmless to the environment. Rapid
and «low permeability, for example, are both con-
sidered severe limitations. Separate criteria for
effluents and for sludges were developed. The two
sets of criteria differ only slightly; in rating soils for
liquid waste-disposal systems infiltration rate is add-
ed as a criterion and class limits for available water
holding capacity are made less restrictive. Require-
ments for water holding capacity are more stringent
for sludge disposal if a crop is to be grown on the site
and for liquid waste disposal if no permanent
irrigation system is installed.
A meaningful national summary of soils judged
suitable for waste disposal by these criteria could not
be presented in the time available at the meeting. In-
stead, I showed a soil map of the United States that
had been modified to show broad areas where the
dominant soils have certain limitations for waste dis-
posal. The relationship of these areas to the major
population centers was self-evident.
Areas including large parts of the Atlantic Coastal
Plain, the Mississippi Delta, extensive areas in south-
ern Illinois, areas around the Great Lakes, and in
Minnesota were shown as wetness being a primary
limitation. All these areas except the one in Min-
nesota contain major metropolitan areas and areas of
rapid urban growth such as in Florida. Areas in
which pollution because of soil slope and the con-
comitant hazard of erosion or because of shallow
soils is a major hazard were also shown. They are
concentrated in the major mountain systems of the
country. Since the mountainous topography has also
been a major restraint for urban development these
areas contain relatively few of our major metropoli-
tan centers. In relatively inextensive areas of sandy
soils, excessive permeability and limited filtering and
absorptive capacity are dominant soil limitations. Al-
though these areas are inextensive, they present a po-
tential pollution hazard. The soils in these areas have
-------
116
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
the capacity to accept large amounts of liquid waste
and they are presently not used intensively. This and
the ownership patterns in these areas tempt their use
for large-scale, land-based disposal systems. This
may eventually lead to serious pollution problems.
Soils of this kind are reasonably extensive near the
Chicago metropolitan area.
Areas in which slow permeability of the dominant
soil is the major limitation are similarly inextensive.
But they are a problem for using soils for land-dis-
posal systems in the Dallas-Ft. Worth and the San
Francisco metropolitan areas.
One must realize that a map of this scale can give
only very general information on broad areas. An
area shown on the map as having certain limitations
may still contain extensive areas that are well suited
to waste-disposal systems. As a rough estimate we can
say that in the area of wet, sloping and mountainous,
and sandy soils discussed so far two-thirds of the soils
are poorly suited for waste-disposal systems but one-
third are suited. The situation is further complicated
by variations in the size of suitable units. Suitable in-
clusions in areas of predominantly sloping and shal-
low soils, for example, tend to be in small units in the
Appalachian Mountains and in rather large units in
the deserts of the Southwest.
In large parts of the country, primarily in the mid-
dle and upper coastal plain of the Atlantic and Gulf
coast and in much of the Midwest, the dominant soils
are suitable for waste-disposal systems but their per-
meability is slow enough that liquid wastes can be ap-
plied only at moderate rates. In addition, up to one-
third of the soils in these areas are unsuitable for
waste-disposal systems. These areas include many of
the major urban centers of the Southeast and the
Midwest, including the industrial areas along the
Great Lakes. Finally, there are areas in which most
soils appear to be well suited for waste-disposal sys-
tems. Few of these areas are near major metropolitan
areas.
This overview of the country gives a very general
picture of the soil resources available for the country
as a whole, but it is not useful for local planning or
site selection. For local planning and site selection
soil surveys are available for about 40 percent of the
country. Individual soil surveys usually cover coun-
ties. They consist of detailed soil maps, usually at a
scale of 1:31,680 to 1:15,840, on a halftone photo-
graphic background, a general soil map of the whole
county, technical descriptions of the soils, measured
and estimated data on the agronomic and engineering
properties of soils and ratings of individual kinds of
soil for the various purposes that have been dis-
cussed. Soil scientists of the Soil Conservation Ser-
vice and of state agricultural experiment stations can
advise on criteria for selecting suitable soils and sites.
Areas that are selected from a detailed soil survey
must, of course, be further evaluated by onsite in-
vestigations.
Climatic Factors
Temperature and precipitation, both amount and
distribution, affect the feasibility and design of dis-
posal systems. During the cold season there is little
microbial activity to decompose wastes and little
evapo-transpiration to remove water. Temperature
regime is not an insurmountable factor, but holding
tanks for the wastes that accumulate during the cold
season and areas for disposing the accumulated
wastes during the warm season add to the cost and the
acreage requirements of systems. Precipitation or,
more correctly, the balance of precipitation and po-
tential evapotranspiration presents a more serious
problem. Solid waste and sludge disposal systems
need moisture for micro-organisms and plant cover
and for leaching salt from the root zone. Solid waste
and sludge disposal systems in arid parts of the coun-
try require supplemental irrigation. Excessive leach-
ing in humid parts of the country must be avoided. In
liquid waste disposal systems the waste water may be
of considerable value, depending on the objectives of
the system. The effluent can recharge aquifers if this
is an objective of the system or it can make up for a
water deficit if recycling of wastes and crop produc-
tion are objectives. The effluent may, however, tax
the absorptive capacity of a system if the excess water
is added to a large natural precipitation. In some sys-
tems the value of the waste water for irrigation is ex-
pected to help defray part of the cost of the disposal
system or to entice farmers to allow use of their land.
This value can be realized only if there is a moisture
deficit.
In designing a system, the total amount of precipi-
tation relative to evapotranspiration, the distribution
of precipitation during the year, and the changes in
precipitation from year to year have to be considered.
Figure 1 shows the excess of mean annual potential
evapotranspiration as estimated from Thornthwaite's
formula over mean annual precipitation for the
United States. The values are in inches. Positive
values, in the western part of the country, indicate ex-
cess evapotranspiration as high as 70 inches. Ob-
viously, the higher the excess of evapotranspiration,
the more waste water can be added to the land with-
out causing leaching and the greater is the value of
the waste water for irrigation. To the east of a line
running slightly to the west of the Mississippi River,
negative values suggest some runoff and leaching
even if no waste water is added to the soil. Actual ex-
cesses and deficits depend, largely, on the distribution
-------
LAND RESOURCES
117
Kigure 1 Potential Kvupotranspiration vs Main Annual Precipitation (Inches)
of precipitation throughout the year. Even in the
humid part of the country there is usually a moisture
deficit during part of the summer; there may be a
large excess of moisture during the winter in arid
parts of the country. Variations from year to year
must also be considered. A system that may work
well in an average year may be seriously overloaded
during an exceptionally wet year. Figure 2 shows the
frequency distribution for precipitation deficits for
six weather stations of the Midwest. The histograms
are rather flat, and the range between the effectively
driest five percent and the wettest five percent of the
years is between 30 and 55 inches. This range of 55
inches is in the same order of magnitude as that for
the mean annual values for approximately 80 percent
of the country. The disadvantages of erratic precipi-
tation can partly be compensated by proper system
design and by restricting disposal sites to the most
favorable soils.
Geologic Factors
The discussion so far has been restricted to indi-
vidual disposal sites and a soil mantle of six feet or
so. For most intensive disposal systems the nature of
the underlying rock must be considered. If the rock is
an unconsolidated soil like material, it may add to the
ability of the soil to absorb and filter. Hard rock un-
OOOGE Cltr KANSAS
CONCORDIA KANSAS
TOPEKA KANSAS
SI JOSEPH MISSOURI
COLUMBIA MISSOURI
JACKSON. MISSOURI
_c
.H
tt^-
It nil Po(fn(. ,i (v i
Figure 2: Frequency Distribution (Normal Potential Evapotrans-
piration vs. Annual Total Precipitation.)
-------
118
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
derlying the soil at shallow depths, particularly if it is
jointed as certain igneous rocks or if it contains solu-
tion channels such as limestone, may detract from the
value of a soil as a disposal medium. Regional
groundwater regimes and the capacity of the ground-
water system to accept the added load must also be
considered. Soil drainage characteristics and ground-
water regimes can be modified through the installa-
tion of drainage systems, but such systems must be
carefully designed not to detract from the ability of
the soil to destroy and absorb pollutants. In the arid
part of the country, the possiblity that a rising
groundwater level may bring dissolved salts from un-
derlying beds within reach of the vegetation must be
considered.
Institutional Factors
In general, soils that are well suited as media for
waste disposal are also desirable for agricultural or
urban development. They may be intensively farmed,
and if they are located near metropolitan areas, the
farms may be relatively small. Hence the cost of pur-
chasing the land or making arrangements with indi-
vidual farmers to use sewage effluents or sludge may
be difficult.
Institutional arrangements will be simplest in those
parts of the United States where irrigation is prac-
ticed and where effluents provide a source of irriga-
tion water that is not otherwise economically avail-
able. Major metropolitan areas in the Southwest have
large acreages of land that are publicly owned or
land in large holdings that are now extensively used.
The availability of such land in the East is limited.
CONCLUSIONS
Soil surveys conducted by the Soil Conservation
Service and its cooperators indicate that soils that are
suitable for land-based waste disposal systems are
available near most metropolitan centers of the coun-
try. Such suitable soils may, however, cover only a
small part of the total landscape in a given area and
considerable care must be taken in locating and
evaluating suitable sites. Climatic and institutional
factors suggest that land-based disposal systems are
likely to be ecologically safer and economically more
attractive in the semiarid and arid western part of the
country than in the humid eastern part.
DISCUSSION
QUESTION: Belford L. Seabrook, EPA,
Washington, D. C. You talked about sites that were
suitable for land disposal. I would like to know
whether you considered the other three types of land
application. That is crop irrigation, infiltration and
overland flow or spray run off, which are definitely
not land disposal. Disposal seems to make everybody
mad and seems to connote something that is bad, so
did you include those and if so, it seems you have
selected a lot of places where you say that land appli-
cation such as overland flow is not suitable. Paris,
Texas is one of the best examples of this, where you
have a dense clay soil and yet, they have been apply-
ing water by overland flow for many years, very suc-
cessfully.
ANSWER: The limitations I discussed were gen-
eral limitations assuming infiltration of water and the
wastes into the soils.
COMMENT: Bob Dean, EPA. There is one area
that Mr. Klaus seems to have left out, in fact most of
us have left out in our discussions, and I see Jim
Evans over here representing that area, namely the
forests. I am not as worried about the food chain
when we go into the forests which are greatly
nitrogen deficient. Certain trees, not all of them, are
very tolerant of metals. They learn to live in the
mountains where often the metals are there. We have
minimum interference with the public health aspects
because there is much less public access and in plan-
tations there is virtually no public access. They keep
you out. The deer hunter won't go more than about
three miles into the forest from a road no matter how
many deer there are further in. This was demon-
strated in New York State very clearly. We are not
looking at the cut over land that was forest, we tried
to crop, we failed, we went west, it surrounds our
cities, some people call it deer pasture, scrub, you
have lots of names for it. It is abundant area. It is
ruled out because you wrote it out universally be-
cause you said it was all too steep, and have you even
seen sludge flowing down over a forested slope and
seen how well it is caught in the forest litter. It
doesn't reach the bottom of the hill. There are a lot of
things we can look at, but sitting back in a little ivory
tower as we said, well, it is going to get into the food
chain, we mustn't put it on the land. Well, there is a
lot more land than that which is used for agriculture
and a lot of that would benefit greatly by applications
of nitrogen.
CHAIRMAN. Darwin Wright, EPA. Do you want
to respond to that9
ANSWER: Klaus W. Flach, USDA. This is quite
correct, but most land that are in forest are there for
a reason and the reason is because the land is steep
and the sludge may not run down the hill but the
run-off water will. A lot of the soils in forest are
shallow. There is rock under it and water will move
-------
LAND RESOURCES
through that shallow soil and move into aquifers. So
there is very definitely a potential.
Secondly, for pollution and thirdly, many of our
metropolitan areas are not near large areas of cut
over forest land. Some are and many are not.
QUESTION: Ken Dotson, EPA, Ohio. Was your
criteria for rating soils primarily based on the
sewerage effluent or the sludge? And to follow it up a
little bit, it appears to me to have been primarily
based on effluent because of the effluent is a problem
of water whereas the sludge is primarily a problem of
solids. Is that correct?
ANSWER: That part of the paper I presented was
primarily directed towards effluents. The limitations
for a soil for sludge disposal would be less as far as
the water holding capacity of the soil would be con-
cerned. On the other hand, if you do want to grow a
crop on your sludge disposal site you have to have
the ability to hold water to grow a crop without ar-
tificial irrigation.
-------
Soil-Plant
Relationships
(Some Practical
Considerations In
Waste Management)
S. W. MELSTED
University of Illinois
ABSTRACT
Soil-plant relationships that may influence munici-
pal sludge and effluent applications on land are dis-
cussed. Among these are nutrient mobility in the soil,
ion absorption by plants, methods of determining
plant composition through soil analysis, importance of
sludge placement to ion absorption by crops and nu-
trient absorption through foliar feeding. Distinction is
made between recycling and disposal of wastes on
land. Several management factors in waste disposal on
land are evaluated. Monitoring problems, especially as
related to soil or plant analysis, are discussed with
plant analysis rated more practical at this time. Nor-
mal plant composition ranges and suggested tolerance
levels for toxic heavy metals are given. Research rec-
ommendations meriting high priorities include (I) de-
fining the available form of heavy metals, (2) correla-
tion studies between soil levels and plant composition,
(3) absorption of noxious compounds from foliar
spray irrigation, (4) determination of residual nutrient
levels in "living filter systems" of effluent treatment,
(5) determination of tolerance levels of toxic heavy
metals permissible in feeds and foods and (6) deter-
mining disposal management systems that maximize
the beneficial properties while minimizing the hazards
from applying municipal sludges and effluents on
land. Additional Index Words: Soil-plant relation-
ships, toxic levels in plants, waste disposal on land.
INTRODUCTION
In nature the soil is the medium which physically
supports and nutritionally feeds the plant. The char-
acteristics of the soil, both physical and chemical,
can have a significant affect on the plant. The pur-
pose of this paper is to call attention to some of the
well established soil-plant relationships as they may
influence the use, the choice of the area and the ex-
pected results from applying municipal sludges and
effluents on farm land.
Municipal wastes contain all of the nutrient ele-
ments essential for plant growth. The essential ele-
ments that plants obtain from the soil are N, P, K, Ca,
Mg, S, Fe, Mn, Cu, Zn, B, and Mo with Se, V, Cl, Na
and Si possibly required for some crops. These are
chemical elements without which the plant cannot
complete its life cycle. In addition, I, Co and F are
essential or beneficial to animals. Other elements like
Ni, Cd, Cr, Hg, Se, As, etc., also are present in many
municipal sludges and effluents and may be consid-
ered as contaminants to the soil-plant-animal-human
food chain. Therefore, the application of municipal
sludges and effluents on land may be considered a re-
cycling process for the essential nutrients and a dis-
posal repository for all other non-essential compon-
ents. The primary consideration, then, becomes man-
agement such that beneficial aspects are maximized
and its adverse affects minimized.
Soil-Plant Relationships
To understand the soil-plant system it is important
to recognize some of the chemical properties of soils
associated with plant nutrition. Almost all soils have
the property of cation exchange. All soil colloids, the
clay minerals and soil organic matter, are negatively
121
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122
KF.CYCLING MUNICIPAL SLUDGES AND EFFLUENTS
charged and are dominantly solid polyvalent anions.
Negative charged sites arise mainly from broken
bonds at the surface and internal substitution groups
within the lattice structure. The inorganic colloids,
e.g., the clay minerals, may also have some anion ex-
change properties from broken bonds at the clay sur-
face giving rise to positive charges. Because the col-
loids are solids, both negative and positive charge
sites can exist on the same particle. The negative
charge sites far outnumber the positive charge sites
and a single soil colloid particle may have several
hundred negative charges and carry a wide variety of
charge-balancing cations. The term "cation exchange
capacity" refers to the measure of the magnitude of
the negative charges and is given terms of milliequiv-
alents per 100 grams of soil. The composition of the
cations on the colloid surface will be a function of
the bonding energy of the cation, which in turn is de-
termined primarily as its hydrated radii and its
charge, and its concentration in the system.
In a soil system the colloid is held in place in the
soil matrix. The cations adsorbed on the colloids are
thereby also held in place and protected from leach-
ing as long as the soil solution is relatively free of
mobile anions.
The inorganic colloids can also, due to their posi-
tive charge sites, adsorb and hold anions on their sur-
face. This is known as anion exchange. Anions may
also be adsorbed through chemadsorption, that is,
bonded through a di- or tri-valent cation held on the
cation exchange complex. Some anions can be ad-
sorbed through surface molecular adsorption. All
three mechanisms are instrumental in retaining high
energy anions on the soil colloid and protecting them
from leaching loss.
Plant nutrients in the soil may be classified as
either mobile or immobile7. An immobile nutrient is
one that is adsorbed on the colloid surface. A mobile
ion, or nutrient, is one that moves freely in and with
the soil water and has essentially no attractive force,
or bonding energy, toward the colloids. Among es-
sential elements occurring in the anion form chloride,
CT, nitrate, NOs, borate, HBO"and sulfate, SO^.are
mobile while anions like the phosphate, HPO" and
H;P04 , and molybdate, Mo04~, are immobile. There
is no completely mobile cation in a soil with cation
exchange properties. It is the exchange capacity, and
the surface adsorption reactions, in a soil that distin-
guish it from greenhouse gravel or solution culture
systems. In hydroponic systems all ions are mobile. In
a soil system all essential nutrients, except the nitrate,
sulfate, borate and chloride ions are immobile.
Therefore, data from nutrient culture studies in
greenhouse hydroponic systems can seldom be ap-
plied or extrapolated directly to soil field conditions.
Plant roots grow and elongate at the root tip.
Growth continues throughout the life span of most
plants. This means that the roots forage for immobile
nutrients as they extend and grow in the soil. The
time interval a given root absorbs immobile nutrients
from a fixed point in the soil is relatively short, three
to five days, for most agronomic crops due to the fact
active water and nutrient absorbing areas of the root
extends only from the maturation zone to the root
cap, a distance of 2-3 cm. Once the root matures to
where the cortex layer forms, the epidermis cells lose
most of their capacity to absorb water and nutrients.
The root, then, must grow toward the immobile nutri-
ents and absorb them from colloids contacted by the
root hairs. Nutrient immobility, in part, determines
the effectiveness of rates and placement practices
used when soils are fertilized. Thus immobile nutri-
ents like phosphorus, potassium or zinc, for example,
placed or broadcast on the surface of a soil after a
cultivated crop is established will have essentially no
effect on the crop as the treatment is placed and re-
mains outside the root feeding zone. The same is true
for sludges applied to the soil surface. Sod crops and
grasses, if the sludge does not cause leaf injury, can
absorb some nutrients through their crown and leaves
and can possibly benefit from surface applications.
A mobile nutrient like the nitrate anion moves in
and with the soil water. Water can and does move
faster in the soil than roots grow and virtually all of
the nitrates within the root zone are available to the
plant. As long as there are nitrates and water in the
root feeding zone the plant grows normally with re-
spect to nitrates. When the supply in the soil is ex-
hausted nitrogen deficiency symptoms on a crop ap-
pear suddenly and dramatically. In contrast phos-
phorus deficiency symptoms will remain with the
plant from the time it is a few inches tall until matur-
ity because phosphorus is an immobile nutrient.
The relationship between the levels of immobile
nutrients in the soil and plant growth and yield have
been reasonably well worked out and such studies
form the basis for rapid soil test calibrations and fer-
tilizer use recommendations. Generally, these rela-
tionships2 ', were expressed through an exponential or
quadratic type of mathematical expression. Bray6 has
used the Mitscherlich equation, log(A - y)= log A -
c, b - ex where:
A = the maximum crop yield
y = yield at any given level of b or b+x
b = quantity of the available nutrient in the soil
x = quantity of fertilizer added
Cj, c = constants
with considerable success. Less satisfactory results14,
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SOIL-PLANT RELATIONSHIPS
123
have been obtained in relating the levels of immobile
nutrients in the soil to the percent mineral composi-
tion of the plant. Here the exponential form1 has
proven more successful. The common form used is:
y = A - ec lh-c x where:
A = percent composition required for maximum
yield
y = percent composition at any given level of b
and x
b = quantity of the available nutrient in the soil
x = quantity of the nutrient added
C] and c = constants
The importance of these expressions is that they show
that the percent composition, and yield, of a crop is a
function of the sum of the original element level, b,
and that added, x, in a sludge or fertilizer. Or stated
another way, adding a fixed quantity, x, of an element
to two soils having different nutrient levels, b, can
produce radically different results. The reason the
relationship between soil nutrient and yield are more
accurately correlated, than soil nutrients and percent
composition, may be due in part to the fact that once
a soil nutrient drops to levels low enough to cause
growth stress, or a decrease in yield, it acts more
nearly as an independent variable affecting growth.
At levels in the plant where growth stress does not
occur considerable interaction between nutrients may
take place. Thus, the interactions2" between Zn-P,
Ca-B, Cu-Al, K-Mg, etc., are but a few of the com-
mon ion-pair interactions documented in the litera-
ture. Any nutrient raised to toxic levels in a plant will
affect the absorption of all other ions as growth de-
creases. The extent to which increasing the levels of
some essential nutrient might be used to suppress ab-
sorption by plants of toxic heavy metals has not been
fully studied and merits research considerations. Tol-
erance levels of plants to any immobile toxic element
is much greater in the soil system than it is in a
hydroponic system. In solution systems ion interac-
tions are much more likely to occur because of great-
er ion mobility and toxicities will occur at lower
levels.
Salts, and soil solution extracts high in salts, may
inhibit the absorption by plants of ions like Ca, Mg,
K and many of the essential heavy metals as well as
create an osmotic pressure outside the root retarding
the movement of water into the roots2. Whenever the
expressed soil solution, a water culture solution, or
irrigation water has an electrical conductivity in ex-
cess of 2 mmho/cm at 25°C, or an osmotic pressure
in excess of 0.72 atmospheres yields of very salt-sen-
sitive crops may be restricted. However, most agron-
omic crops are less sensitive to salts and yield depres-
sions may not occur until the electrical conductivity
in the expressed soil solution is over 4 mmho/ cm at
25°C, or its osmotic pressure is over 1.44 atmos-
pheres. Salts, especially those associated with wastes,
are high in mobile anions as nitrates, chlorides and
sulfates. Besides contributing to the salinity of the
soil solution these mobile anions add greatly to the
leaching loss of bases from the soil. Any anion that
leaches through a soil must carry with it cations to
balance its charges. Cation levels in drainage waters
accompanying mobile anions are determined, not by
the solution composition on entering the soil, but by
the cation exchange composition of the soil at the
point of departure.
Two mechanisms of nutrient uptake by plant roots
are recognized, active uptake and passive entry. Ac-
tive uptake is the dominant entry pathway of cations
once they are adsorbed on the root exchange surface.
This is a very aerobic process by which the plant can
accumulate cations against nutrient gradients and by
which it exercises a degree of discrimination against
cations present in the biosphere. Passive entry is the
major pathway for anions. The plant has little, or no,
capacity to selectively discriminate between the an-
ions absorbed by the roots. Diffusion is the major en-
try mechanism which is regulated by the plant cells
and which is needed to maintain electrical neutrality
with the cations actively accumulated.
In agriculture it is a common practice to spray
leaves of plants, especially citrus, with dilute single
salt solutions of an essential heavy metal to alleviate
deficiencies in plants if the soil is deficient in that ele-
ment'026. Zinc, iron, copper, and manganese, usually
as sulfates, and urea are most commonly used. The
leaf has limited capacity to absorb nutrients supplied
to it in this manner. Since the metals are immobile ca-
tions strongly adsorbed on the colloid surface and are
not likely to leach down to the root feeding zone if
applied as a fertilizer to the surface of the soil, foliar
spraying is the only expedient method of getting small
amounts of these micronutrients into the plant. The
leaf has essentially no selective capacity to preferen-
tially absorb one nutrient over another. Thus a leaf
will absorb any element contained in a spray solu-
tion. Generally the efficiency of absorption of a de-
sired nutrient is low and decreases if the spray solu-
tion contains other salts. As with the root, if a spray
solution has an electrical conductivity of 4
mmho/cm at 25°C, or an osmotic pressure over 1.44
atmospheres, damage to leaves is likely to occur.
Plant leaves are quite sensitive to toxic gas fumes in
the air". Most plants are particularly sensitive to
ozone, 03, nitrogen mono- and di-oxides, NO and
NO2, fluorides, F2 and HF, and sulfur dioxide, SO2.
For agronomic crops 0.3 ppm Oj or 1 ppm of com-
bined NO and NO2 in air are considered detrimental
-------
124
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to growth. The sensitivity of leaves to noxious ele-
ments in spray solutions has not been determined
adequately and merits further research.
Plants differ in their capacity to absorb nutrients
from the soil. Some of these differences are genetic in
origin and are associated with the physical distribu-
tion, e.g., fiberous vs tap root systems, and their
chemical characteristics e.g., cation exchange capa-
city and pH. Plants also differ in root configurations'
and in their capacity to transport nutrients, or toxic
substances, from the roots to the above-ground
vegetative structures. Transport from the stem and
leaves to the seed can also vary for different species.
The seed is a highly specialized, reproductive struc-
ture whose mineral composition will remain fairly
constant although rather large changes may take
place in the vegetative tissue. Therefore, the leaf of
most plants reflects environmental and nutritional
changes more readily than the seed.
Application of Wastes to Land
The application of municipal sludges and effluents
to land is a desirable practice both from the stand-
point of recycling and reuse of plant nutrients and
from the need of municipalities for adjacent disposal
sites. With proper management and monitoring con-
trols, land disposal can be a highly effective and de-
sirable practice117. Management practices involve
considerations of several soil-plant relationships,
some of which will be considered in the following
discussion.
Objectives and philosophies regarding applications
of municipal sludges and effluents on land will vary
with location, soil characteristics at application sites
and individual evaluations of environmental impacts.
Thus the use of abandoned strip mine areas for waste
disposal differs materially from recycling on actively
productive crop land. In the case of strip mine sites
the objective is primarily the disposal of the waste
with land reclamation and nutrient recycling second-
ary objectives. The purpose of the reclamation is
usually to produce a vegetative cover to lessen soil
erosion and acid mine water drainage. Projected uses
of the land are usually undefined and probably in-
volve some form of industrial, recreational or resi-
dential use, not food production. Under such condi-
tions the food quality of the vegetation except as it
may affect wildlife on the disposal site, is given minor
importance and high concentrations of toxic metals,
up to where they start to impede plant growth, can be
tolerated.
Where municipal sludges and effluents are applied
to productive farm land, the primary objective be-
comes their use as a source of plant nutrients for
maximum crop production. Since all good farm land
is well drained, the rate of waste application must be
a balance between an amount that supplies adequate
levels of nutrients, usually set by their nitrogen and
phosphorus content, and the probable loss of nitro-
gen, either through runoff or leaching, adding to
groundwater contamination. Only through surface
runoff and erosion can appreciable quantities of im-
mobile ions be lost from the soil. Management prac-
tices can be directed toward minimizing both the
leaching and runoff losses and the actual uptake of
noxious compounds by the crop. Under normal con-
ditions crops are very low in toxic heavy metals and
from an environmental point of view it is desirable to
keep contaminants out of the food chain. Many of the
toxic heavy metals are immobile and can remain in
the soil for many years. As a temporary safe exped-
iency for the disposal of municipal sludges and efflu-
ents the heavy metals may be increased in the soil and
plants without doing permanent damage to either.
But it is unrealistic to think of good farm soil as a
continual disposal area for the industrial toxic heavy
metal wastes now incorporated into the metropolitan
sanitary sludges and effluents. It should be remem-
bered that municipal sludges and effluents containing
non-essential noxious chemical compounds cannot
be expected to enhance the soil for crop production
but rather that they will not deleteriously affect, un-
der controlled applications, the soil to where crop
yields and quality are impaired. After noxious con-
taminants are removed from sanitary wastes, sludges
can become a valuable fertilizer for crops and its dis-
posal on land should be encouraged.
Farm soil is usually plowed and cultivated to a
depth of six to eight inches. Therefore, municipal
sludges and effluents applied to such land will essen-
tially be incorporated into the surface plow depth.
Since all toxic heavy metals are immobile in the soil,
plant roots, after they penetrate the soil below the
plow depth, will be feeding in uncontaminated areas.
This means that early harvested hay crops whose
growth occurred while most of the roots were feeding
in the surface plow layer would have a relatively
higher content of any added toxic metals than the
later growth, as for example the first cutting of a
legume versus the second or third cutting. Similarly,
corn and soybean grain would contain relatively low-
er toxic nutrient levels than the stover and straw be-
cause a bigger proportion of the roots are now in the
deeper untreated soil. In contrast, if the sludge were
applied to the 12 to 18 inch depth, the heavy metal
content of the early growth would be relatively lower
than later growth. Thus placement of sludge, like fer-
tilizers, can greatly influence the heavy metal com-
position of different portions of the crop. The more
uniformly the treatment can be mixed into the soil the
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SOIL-PLANT RELATIONSHIPS
125
smaller will be the relative proportion of any element
absorbed because plant roots contact only a very
small portion of the total colloid surface area. If the
sludge is applied to the soil surface with no mixing, or
cultivation, then only a very small proportion of the
immobile elements will find their way into the crop.
The use of land, or sandy soils with considerable
permeability and some cation exchange capacity, as a
tertiary water treatment facility for sanitary effluents
present problems that need careful evaluation. The
system requires soils with two basic properties, per-
meability and adsorption capacity, to remove ions
from the water, but these tend to counteract each
other. The system may be likened to a water softener
where the entering water high in calcium and mag-
nesium exchanges these ions for sodium ions held on
the softener's exchange material. In the field, often
referred to as the living filter system, the surface sand
will adsorb the noxious compounds from the water
and replace them with whatever ions are attached to
the subsoil sand at the point where the water leaves
the filter system. The higher the exchange capacity of
the sand the greater its purification ability. But in-
creasing exchange capacity means increased clay
content and decreased water permeability12. There-
fore, one aspect of site selection is the balance be-
tween soil permeability and ion adsorption capacity.
A sand, or gravel, field devoid of clay particles and
exchange properties would simply be a large scale
hydroponic system. A productive silt loam soil with
high ion adsorption capacity would have an infiltra-
tion rate too low to operate successfully as a filter
system.
When a salt solution is passed through a soil an
equilibrium is established between the cations on the
soil colloids and those in the leaching solution. The
resulting equilibrium established in the soil is a func-
tion of the composition and concentration of the salts
in the effluent solution and the cation composition of
the colloids22. It is unlikely this equilibrium will pro-
duce a cation composition in the surface of a sandy
soil that is ideal for high crop production. While such
equilibria can be calculated for the common essential
nutrients whose bonding energies are known, the
bonding energies precipitate formations and the gen-
eral soil reactions of many of the toxic heavy metals
are not known and their relative total adsorption is
difficult to determine. Research in this area is urgent-
ly needed.
Anion adsorption from the effluent water must also
take place. Phosphate anions will dominate the suite
of immobile anions with smaller amounts of chro-
mate, arsenate, borate, molybdate, selenate and the
many other anions present in smaller amounts. In
sandy soil it is unlikely the anion exchange adsorp-
tion capacity will be sufficient to extract all immobile
anions from the effluent. Purification, or removal,
will depend on their being precipitated from the solu-
tion. The most likely precipitant, or absorbing agents,
will be lime and iron and aluminum gels that the
sands may contain. Sulfate, borate and chloride an-
ions will move through the sand, except for the small
amount that may be absorbed by the crop.
Removal of the mobile nitrate anion will require a
living crop on the sand whose root system can absorb
nitrates from the effluent water as it leaches down-
ward. The efficiency with which roots can absorb ni-
trates from the moving effluent solution will depend
on climate, soil and air temperatures, nitrogen needs
of the crop, nature and distribution of the crop's root
system, maturity stage of the crop and the downward
How rate of the solution. This is an area where con-
siderable research is required and should include,
among other things, the following:
1. Determination of the residual level of nitrates
various crops will leave in a flow solution cul-
ture system.
2. Determination of the influence of various flow
rates on all nutrient absorption by crops.
3. Determination of the minimum root density re-
quired for effective nitrate removal.
4. Determination of the effect of various seasonal
factors, especially temperature and sunlight, on
nitrate absorption from leaching solutions, e.g.,
are nitrates absorbed at night?
Tertiary treatment of effluents with living land fil-
ter systems usually envisions an overhead irrigation
system operating daily throughout the crop-growing
season. While overhead irrigation systems have been
used in agriculture for years, sometimes using fairly
salty water, intense daily irrigation with effluents
containing many noxious compounds and toxic heavy
metals have not been studied, especially as relates to
toxic metals absorption through the leaf surfaces.
This is an area that requires intensive research which
might include the following:
1. Determine the repression, if any, from daily
spraying of leaves with effluents containing
noxious compounds.
2. Determine the amount of toxic heavy metals, like
Ni, Cd, Cr, Pb, etc., absorbed through the leaves
under continuous spray regimes, that various
crops can tolerate. Are toxic heavy metals more
harmful when absorbed through the leaf sur-
faces?
3. What is the salt tolerance of various crops under
continuous overhead irrigation as compared to
soil irrigation?
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126
RECYCLING MUNICIPAL SLUDGES AND EKFLUKNTS
Monitoring Disposal Systems
Monitoring the effects of applying municipal
sludges and effluents on the soil and on the resulting
vegetation is a necessary follow-up of such practices.
Two approaches are possible, or they can be used to-
gether. One is systematic soil analysis and the other is
plant analysis. Both have limitations that could be re-
solved with research and each has desirable charac-
teristics under given conditions. A brief discussion of
each follows.
Soils differ widely from region to region. From the
standpoint of monitoring such differences in soil
characteristics as clay type and amount, pH and car-
bonates, and soil organic matter can influence the
stability of the available plant forms and hence the
nature of the chemical reagent required to extract the
element from the soil. Thus manganese, aluminum,
iron and most of the heavy metal cations as well as
phosphate, molybdate and many of the toxic anion
forms are examples of ions whose stability vary
greatly with changes in pH and organic matter24.
From past experience, and the inability to establish
uniform soil testing methods for the determination of
available essential heavy metals like zinc and copper
under a wide range of soil conditions, the likelihood
of developing standard methods of analyses for the
toxic elements are rather remote. Analytical methods
for determining the total quantity, and in some cases
the available form of some toxic heavy metals in soils
are available for some regions. But as indicated ear-
lier, the toxic heavy metals in the soil or added in
sludges and effluents must be in a form that plants
can absorb to impair crop quality. If the available
forms are known, soil test procedures can be devel-
oped to determine their quantity both in the soil and
in the waste materials. Methods of analysis for avail-
able essential metals are well developed for different
soil regions. These methods can be expanded to cover
the toxic range as well as the deficiency range for
which they were established. In contrast, consider-
able research is required to establish the available
forms for many of the toxic metals and to develop
testing methods for these forms before soil analyses
can become an effective monitoring tool.
The objectives of the monitoring and the soil
analysis are to prevent the buildup of noxious com-
pounds in the soil to the point drainage waters be-
come contaminated, permanent damage is done to the
quality of food, feed or fiber crops, or accumulations
reach levels that are directly toxic to plants. This be-
comes a special hazard when the land is used for dis-
posal rather than recycling of wastes. Soil analyses
require that the analytical values be correlated to
plant composition in such a way that accurate and
dependable predictions of plant compositions can be
made. At this stage of development'4' such correla-
tions are not reliably developed and much research is
needed.
Plant analysis, at the present time, probably offers
the most logical nation-wide approach possible to the
monitoring problem. The plant is the final arbitrator
of the impact of the treatments and their reactions in
the soil as they affect crop quality. Such factors as
nutrient mobility, nutrient solubility, placement and
use of entry into the plant, both through the roots and
leaves, and translocation within the plant are all re-
flected in the final plant composition. Standard
analytical methods for plant analyses are available
and uniformly applicable on a national scale.
Plant analysis, to be an effective monitoring tool,
requires that normal composition and upper toler-
ance levels be known and set for the indicator plant.
The average range in composition for many
crops"" '<"•""""" ' "•••' grown under various soil and cli-
matic conditions have been published. What is less
well known, and on which differences of opinions
will undoubtedly exist, are the permissible upper tol-
erance levels for toxic substances in plants that rep-
resent complete safety with respect to the food chain
and to all future foreseeable uses of the land. The
values given in Table 1 are presented to this work-
shop conference for the purpose of discussion and to
record the authors judgment with respect to tolerance
levels acceptable for some of the common feed and
food crops if they are used for monitoring purposes.
It cannot be overemphasized that these tolerance
values are the author's and are not specifically docu-
mented in the literature. Land producing crops that
normally contain nutrient levels above the tolerance
level should be carefully evaluated before being used
for waste disposal. The tolerance levels presented
here are, by most standards, conservative.
The data in Table 1 needs considerable explana-
tion. First, the chemical form most readily absorbed
by plants is given in the column headed "probable
available form". For many of the cations and anions
the available form, or form absorbed by crops is well
established. For some of the anions the available
chemical form in soil is not well established. For
example, most data tend to show that the chromate
anion is more available than the chromous or chrom-
ic cations, and that the selenate anion is more avail-
able than the selenite anion or the selenium cation
forms. A knowledge of the chemical forms preferen-
tially absorbed from the soil by plants is of crucial
importance to a soil analysis program and to evaluat-
ing harmful contaminations. This is an area requiring
considerable research.
Plant analyses will require that a specific portion
of the plant, harvested at a specific stage of develop-
ment be used for monitoring purposes. Many of the
-------
SOIL-PLANT RELATIONSHIPS
127
TABLE 1
The Probable Available Form, the Average
Composition Range for Selected Agronomic
Crops, and the Authors Suggested
Tolerance Level of Heavy Metals In
Agronomic Crops When Used for
Monitoring Purposes.
Probable
A vailable
Form
Common Average Suggested
Composition Tolerance
Range"' Level*''
ppm ppm
Barium
Cadmium
Cobalt
Copper
Iron
Manganese
Mercury
Lithium
Nickel
Lead
Strontium
Zinc
Ba+
Cd+
Co+
Cu +
Fe +
Mn+
Hg*
Ni+ +
Pb + +
Sr + +
Zn + +
Cations
10-100
0.05-0.20
0.01-0.30
3-40
20-300
15-150
0.001-0.01
0.2-1.0
0.1-1.0
0.1-5.0
10-30
15-150
200
3
5
150
750
300
0.04
5
3
10
50
300
Arsenic
Boron
Chromium
Fluorine
Iodine
Molybdenum
Selenium
Vanadium
Probable
Available
form
AsO"4"
HBOV
CrO4-
F~
r
MoO4~
SeO'4"
VOj
Common Average Suggested
Composition Tolerance
Range* Level**
ppm ppm
Anions
0.01-1.0
7-75
0.1-0.5
1-5
0.1-0.5
0.2-1.0
0.05-2.0
0.1-1.0
2
150
2
10
1
3
3
2
* Average values for corn, soybeans, alfalfa, red clover, wheat,
oats, barley and grasses grown under normal soil conditions. Green-
house, both soil and solution, values omitted.
* * Values are for corn leaves at or opposite and below ear level at
tassel stage, soybeans - the youngest mature leaves and petioles on
the plant after first pod formation, legumes - upper stem cuttings in
early flower stage, cerals - the whole plants at boot stage, and
grasses - whole plants at early hay cutting stage.
common agronomic crops are quite similar in their
average range of nutrient content, including toxic
metals, when grown under similar conditions and
harvested at specified stages of development. The
average common composition ranges were calculated
from composition data reported in the literature for
crops grown on normal soils. The following crops,
corn, soybeans, legumes (mostly alfalfa and red
clover), cereals (wheat, oats and barley), and grasses
(miscellaneous) are included in the averages. In as far
as possible the composition data apply to the follow-
ing plant parts and designated stages of development:
Corn - leaf at, or opposite and below, ear level at
tassel stage.
Soybeans - the youngest mature leaves and petioles
on plant after first pod formation.
Legumes - upper stem cuttings in early flower
stage.
Cereals - the whole plant at the boot stage.
Grasses - whole plants at early hay cutting stage.
Generally, the upper common range level is that
found on soils tending to be high in that element.
Thus, for example, the upper selenium values are
high for Illinois but fairly common for grasses in
some sections of South Dakota. The suggested crop
sampling stages are easy to identify in the field and
hence lend themselves to more reliable monitoring.
The permissible tolerance levels suggested in Table
1 for agronomic crops assumes the following:
1. That the same tolerance levels can be used for
the common agronomic crops.
2. That the above designated plant part and stage
of development will be used.
3. That the municipal sludges and effluents are be-
ing recycled, or used as a fertilizer. This implies
a rate of application commensurate with crop
needs.
4. That the land is productive agricultural land to
be used for crop production for generations to
come.
5. That many of the noxious compounds in the
wastes become immobile when added to the soil
and will remain there indefinitely.
6. That the crop will probably absorb a part of any
toxic heavy metal or noxious compound added
to the soil.
7. That the tolerance level includes an acceptable
safety factor. Therefore, the suggested levels are
only one-half, or less, of the values the literature
suggests as being:
a. Toxic levels for animals.
b. Plant levels at which appreciable transfer of
the element from the vegetative portion of the
plant to the grain occurs.
c. The level known to be toxic to the plant itself.
Again, it is emphasized that these tolerance levels,
Table 1, are judgment values at this time presented
for discussion purposes at this workshop conference.
Others may feel that these values are too high or too
low depending on the ultimate use of the crops and
their dilution with feeds or foods from untreated
areas, or in their evaluation of the hazard of such
levels in the food chain. The lack of more definite
data does suggest, however, the need for research in
this area. Among the many research needs are:
-------
128
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
1. Establishment of more definite toxicity levels for
heavy metals and noxious compounds in feeds
and food for animal and human consumption.
2. Establish the efficiency with which crops can ab-
sorb toxic elements from an agricultural soil.
3. Establish the chemical forms noxious com-
pounds must be in for plants to absorb them
from the soil.
Sanitary wastes, free of noxious compounds, are an
excellent source of many nutrients required for plant
growth. Because most of the toxic elements found in
municipal sludges or effluents are immobile when ad-
ded to the land, appreciable quantities can be incor-
porated into the soil without any significant detri-
ment to crop quality. Considerable technical upgrad-
ing of existing sanitary waste treatment facilities and
recovery techniques for point source contaminants
will be required before municipal sludges and efflu-
ents are free of toxic or noxious compounds. While
such technical upgrading is taking place, recycling of
municipal sludges and effluents on appropriately
chosen farm land under good management practices
should present no hazard to the soil or decrease in the
quality of farm crops. Controlled land applications of
wastes free of noxious compounds can be highly de-
sirable and should be encouraged.
LITERATURE CITED
1. Allaway, W. H. 1968. Agronomic controls over
the environmental cycling of trace elements. Ad-
vance Agron. 20: 235-275.
2. Allison, L. E. 1964. Salinity in relation to irriga-
tion. Advance in Agron. 16: 139-180.
3. Balba, M. A. 1958. Calculation of the uptake of
different nutrient forms. Alexandria Jour, of Agric.
Res. 6: 81-92.
4. Balba, M. A., and L. E. Haley. 1956. Compari-
son of results obtained by the Balba-Bray equation
and radioactive techniques for the determination of
nutrient uptake by plants from different nutrient
forms. Soil Sci. 82: 305-368.
5. Barley, K. P. 1970. The configuration of the root
system in relation to nutrient uptake. Advance
Agron. 22: 159-201.
6. Bray, R. H. 1944. Soil - Plant relationships: 1.
The quantitative relation of exchangeable potassium
to crop yields and to crop responses to potash addi-
tions. Soil Sci. 58: 305-324.
7. Bray, R. H. 1954. A nutrient mobility concept of
soil-plant relationships. Soil Sci. 78: 9-22.
8. Chapman, H. D. 1966. Diagnostic criteria for
plants and soils. Univ. of Califocnia, Div. of Agric.
Sci., Riverside, Calif.
9. Ellis, J. H., R. I. Barnhisel, and R. E. Phillip.
1970. The diffusion of copper, manganese, and zinc as
affected by concentration, clay mineralogy, and asso-
ciated anions. SSSA Proc. 34: 866-870.
10. Foy, C. D., G. Montenegro and S. A. Barber.
1953. Foliar feeding of corn with urea nitrogen. SSSA
Proc. 17: 387-390.
11. Gilbert, F. A. 1949. Mineral nutrition of plants
and animals. Univ. of Okla. Press.. Norman. Okla.
12. Harward. M. D., and N. T. Coleman. 1953. Ion
equilibria in the presence of small amounts of elec-
trolyte. SSSA Proc. 17: 399-342.
13. Heggestad, H. E., and W. W. Heck. 1971. Na-
ture, extent, and variation of plant responses to air
pollutants. Advance Agronomy 23: 111-145.
14. Hincsly, T. D., R. L. Jones, and E. L. Zieglcr.
1972. Effects on corn by applications of heated an-
aerobically digested sludge. Compost Sci. Vol. 13,
No. 4.
15. Huffman, E. W. D. Jr., and J. F. Hodgson. 1973.
Distribution of cadmium and zinc/cadmium ratios in
crops from 19 States east of the Rocky Mountains.
Jour. Environ. Qual. 2: 289-291.
16. John, M. K., C. J. VanLaerhoven, and H. H.
Chuah. 1972. Factors affecting plant uptake and
phytotoxicity of cadmium added to soils. Environ.
Sci. and Tech. 6: 1005-1006.
17. Law, J. R. 1968. Agricultural utilization of
sewage effluent and sludge. An annotated biblio-
graphy. Fed. Pollution Control Admin. U.S. Dept. of
Interior.
18. Lisk, D. J. 1972. Trace metals in soils, plants,
and animals. Advance Agron. 24: 267-325.
19. Melsted, S. W., H. L. Motto, and T. R. Peck.
1969. Critical plant nutrient composition values use-
ful in interpreting plant analysis data. Agr. Jour. 61:
17-20.
20. Munson, R. D. 1966. Interrelationships of nu-
trient elements. Plant Analysis Workshop for Indus-
try. O'Hare Inn, Des Plaines, 111.
21. National Research Council. 1961. Status and
methods of research in economic and agronomic as-
pects of fertilizer response and use. Natl. Res. Coun-
cil Sci. Natl. Res. Council. 2101 Constitution Ave.,
Wash., D.C.
22. Overstreet, R., and K. L. Babcock. 1956. Com-
mentary on activities and Donnan effects. Inter.
Congr. Soil Sci., Paris, France.
23. Sauchelli, V. 1969. Trace elements in Agricul-
ture. Van Nostrand Reinhold Co., New York.
24. Schnitzer, M., and S. I. M. Skinner. 1967.
Organo-metal lie interactions in soil: 7. Stability con-
stants of Pb + +-,Ni + +-,Co + +-, Ca + +- and Mg - fulvic
acid complexes. Soil Sci. 103: 247-252.
25. Underwood, E. J. 1962. Trace elements in
human and animal nutrition. Acad. Press, New York.
26. Volk, R., and C. McAuliffe. 1954. Factors af-
fecting the foliar absorption of '"'N-labeled urea by
tobacco. SSSA Proc. 17: 339-342.
27. Wallace, A. 1971. Regulation of the micronu-
trient status of plants by chelation agents and other
factors. Edward Brothers, Inc. Ann Harbor, Mich.
-------
Crop and Food
Chain Effects
of Toxic Elements
In Sludges
and Effluents
RUFUS L. CHANEY
United States Department of Agriculture
ABSTRACT
Sewage sludge and effluent are applied to soil with
the intent that toxic elements he retained by the soil.
These elements will accumulate and persist, and are
the lung term environmental hazard in land applica-
tion. Elements in sludge and effluent that are potential
hazards to plants or food chain are: B, Cd, Co, Cr, Cu,
Hf>, Ni, Pb, and Zn. The direct toxicities to plants
from Zn, Cu, and M are discussed in detail. Hazard to
the food chain from Cd, Cu, Zn, Pb, and Hg in crops
grown on sludge- and effluent-treated soils is dis-
cussed, with emphasis on the controllable hazard from
Cd. Crop differences in injury from, and accumulation
of Cd, Cu, Zn, and Ni are discussed in relation to the
high phosphate and organic matter contents of sludge
and effluent. Interim recommendations are made for
permissible levels of toxic metals added to agricultural
soils. Research needs to protect plants and the food
chain are presented.
INTRODUCTION
Toxic heavy metals are the long-term hazard in
land application of sewage sludges and effluents. Al-
though I will discuss how we can manage soils and
crops to minimize the possibility of injury to crops
and the food chain, I do not support sludge or efflu-
ent applications which will apply metals in excess of
that which allows continued general agricultural use
of the land involved. We must consider toxic metal
information in choosing any scheme for land applica-
tion of sewage sludge and effluent.
The toxic metal considerations apply to the three
general land application philosophies: (1) Use low
metal sludges as fertilizer (N, P, Zn, Cu); (2) use low
metal compost as a soil conditioner because of its or-
ganic matter, organic N, and P contents; and (3) use
land as a repository for toxic metals to prevent pollu-
tion of air and water, and manage so as to prevent in-
jury to food chain. In each case, the system design in-
cludes holding all toxic metals in the soil. The metals
are added in large to extreme excess of crop removal,
and will be affected by agricultural management
practices long after they are added. Even though we
can manage land application sites to control short-
and long-term hazards from N, organic matter, and
pathogens, the toxic heavy metals will accumulate
and/ or persist, thus becoming the long-term hazard
to the environment.
Sources of Toxic Elements
Many materials added to soils may contain toxic
heavy metals. Sewage sludge contains Zn, Cu, Ni, and
Cd in excess of soil levels (Table 1). Sewage effluent
contains Zn, Cu, and Cd, and has led to soil accumu-
lation of toxic elements. Municipal refuse, raw or
composted, contains Zn, Cu, and B. Animal manures
can contain sewage sludge levels of Cu and Zn if
these elements are added to feeds at growth stimulant
levels much higher than that required to correct Cu
or Zn deficiency for the animals. Even chemical fer-
tilizers may contain high levels of Cd from the phos-
phate rock used to make superphosphate4'. Some
commericial fertilizers contain sewage sludge as an
organic N source or as a cheap bulking agent. The
129
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130
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
discussion in this paper will deal with all aspects of
toxic heavy metals added to soils and plants, with em-
phasis on sewage sludge and effluent which contains
high levels of phosphate.
TABLE 1
Range of Metal Contents
In Digested Sewage Sludge
Element
Zn
Cu
Ni
Cd
Cd
B
Ph
Hg
Olnerveil Range
500-50,000 ppm
250-17,000 ppm
25-8,000 ppm
5-2,000 ppm
0 1-40% of Zn
15-1,000 ppm
100-10,000 ppm
<1-10 ppm
What Elements Should Be Considered?
Any element can he toxic if it is present in a large
enough amount. We must limit our concern to those
elements that greatly exceed normal concentrations,
or will become so through repeated application of
sludge or effluent. These include B, Cd, Co, Cr, Cu,
Hg, Ni, Pb, and Zn. These commonly occur in sludge
and effluent, and can be toxic to the plants grown on
sludge- or effluent-treated soil or to the animal that
consumes these plants.
Toxicity to Plants
Chromium appears to be noninjurious because it
occurs at Cn+ in sludge and as such is not available to
injure plants. Chromate is rapidly reduced to Cr.i+ in
soil. Mercury does not injure plants at the low levels
added with sludge and effluent. Cadmium can be
toxic to plants, but as explained below, this element is
considered hazardous to the food chain at low levels
and thus dare not reach phytotoxic levels. Lead can
injure plants in low phosphate, acid soils. Pb added
with sludge and effluent appears to be nontoxic to
plants because the large amount of phosphate also
present ties up the Pb and prevents injury. Sludge or
effluent seldom contains cobalt, which is a product of
specific industrial pollution. If present, Co is much
like Ni in toxicity, except that it rapidly reverts into
Mn oxides in the soil. Boron in excess can injure
plants; high levels of B can occur in raw or com-
posted refuse. Boron in effluents could become
phytotoxic in soils where we are now concerned
about the B content of normal irrigation water.
Zinc, copper, and nickel are clearly toxic to plants
and commonly occur in sewage sludge and effluent.
The comments below relate especially to the to\icit>
of Zn, Cu, and Ni to plants.
Factors Controlling Metal
Toxicity to Plants
A.The amount of toxic metals present in the soil.
B.The toxic metals present. Zn, Cu, and Ni differ
in their toxicity to specific plants and in specific
soils. Generally, Cu is twice as toxic as zinc, and
Ni is eight to ten times as toxic as N. Chumbley''
introduced the Zn(equivalent) factor Ippm
Zn(equivalent) = 1 x ppm Zn +2 x ppm Cu +8 x
ppm Nil to take into account the differences
among metals. He suggested that no more than
250 ppm Zn(equivalent) be added to agricultural
soils (with pH maintained >6.5).
C.The pH of the amended soil. The toxic metals
are much more available pH's below 6.5-7.0. A
soil toxic metal content safe at pH 7 can easily
be lethal to most crops at pH 5.5. Soil pH may
be more important than the amount of metal ad-
ded. Further, land disposal of sludge leads to a
lowering of the soil pH due to nitrification of the
high amounts of NH4 -N added. Liming can cor-
rect this acidity if the NH4 is in the tillable layer
of the soil. Effluent irrigation generally leads to
a soil pH of 6.5-7.2 as the soil comes to equili-
brium with the neutral effluent.
The effects of zinc level and soil pH on injury
to chard plants are shown in Table 2. Inorganic
Zn (and Cd at one percent of the added Zn) was
added to a Sassafras sandy loam soil and the pH
was adjusted to 5.3, 6.4, or 7.2 in the metal-
amended soil. The yield reduction shows a pro-
nounced pH effect.
D.The organic matter (O.M.) content of the
amended soil. Organic matter chelates the toxic
TABLE 2
Effect of Zn Added and Soil pH
On Zn Content and Yield Reduction
of Chard Leaves
Still pit
64 ,72
flK Zn/f> dry weight
Added Zn
ppm
1.31
32.7
65.4
131.
262.
5 3
210
754
1058(7)'
2763(41)
2692(95)
116
237
337(5)
765(9)
1678(22)
12
74
100
177
406(27)
'Yield Reduction in parentheses (%)
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
metals and makes them less available to injure
plants. The O.M. is especially important in bind-
ing Cu and Ni. Chelation appears to be more im-
portant than the simple cation exchange role of
the O.M. At lower pH's, the O.M. reduces metal
availability relative to the same soil without the
O.M.; however, at high pH, the O.M. appears to
increase availability, at least for Zn. The O.M.
can also slow reversion of metals to unavailable
forms. Because of the importance of O.M. in
protecting against metal toxicity, management of
O.M. is very important.
As the organic matter added with the wastes
gradually decomposes2'', its protective effect is
lost. Leeper'' discussed the disappearance of
O.M. added with sewage sludge and how a soil
could be built up to high metals and O.M. level
and remain nontoxic to plants, and yet ten years
later with no further O.M. addition could be-
come toxic as O.M. disappeared. Miller and
Zaebst'" found that sludge O.M. was no more
stable than soil organic matter, and part of
sludge O.M. was oxidized quite rapidly.
Crop rotation, green manuring, or other prac-
tices which maintain high O.M. should help re-
duce metal toxicity. Even additions of more
sludge may reduce existing metal toxicities in
spite of adding more metals with the O.M.17. Cli-
mate influences the persistence of O.M. in soil
and thus indirectly affects the potential for metal
toxicity.
E.The phosphate content of the amended soil.
Phosphate is well known for reducing Zn avail-
ability to plants and decreasing the stunting in-
jury caused by excessive levels of toxic metals.
However, PO4 enhances iron deficiency chlorosis
caused by excess Cu and Ni4". Sludge and efflu-
ent will add considerable PO4 with the metals
they supply to soils. Application of 50 T/ Ac of a
sludge containing four percent P adds 4000 Ibs
P/ Ac. This is an extremely large amount, and P
buildup may become a limiting factor in sludge
application for P-sensitive crops, e.g., soybeans.
No published data are available to estimate the
interaction of pH and PO4 on Zn toxicity.
F. The cation exchange capacity (C.E.C.). The
C.E.C. of the soil is important in binding all ca-
tions, including the toxic metal cations. This in-
cludes the C.E.C. of the O.M. (which also che-
lates toxic metals, see above), and of the clay
colloids. A soil with high C.E.C. is inherently
safer for disposal of sludge and effluent than a
soil with low C.E.C.
G.Reversion to unavailable forms. The toxic
metals "revert" with time to chemical forms less
available to plants. Reversion has been clearly
established for Zn' and can be quite rapid1 s. The
process of reversion is poorly understood, but
reversion is most rapid in calcareous soils. The
soil pH, PO4 and O.M. contents, and amount of
newly added toxic metal can each affect rever-
sion rate and extent. Cobalt reversion is related
to the amount of Mn oxides in soil. No clear evi-
dence is available on the reversion form of other
toxic metals. Reversion of some metals can be
reversed by prolonged soil submergence12, and
especially by a pH decrease. On a poorly man-
aged site, the rapid O.M. destruction and low pH
may actually lead to a net increase in toxic metal
availability and injury even though the pH re-
mains unchanged.
H.The plant grown on sludge- or effluent-treated
soil. Plant species vary widely in tolerance to
toxic metals, and varieties within a species can
vary three- to tenfold. Vegetable crops very sen-
sitive to toxic metals are the beet family (chard,
spinach, redbeet, and sugarbeet), turnip, kale,
mustard, and tomatoes. Beans, cabbage, and col-
lards, and other vegetables are less sensitive.
Many general farm crops (corn, small grains,
and soybeans) are moderately tolerant. Most
grasses (fescue, lovegrass, Bermudagrass, or-
chardgrass, and perennial ryegrass) are tolerant
to high amounts of metals. Highly tolerant eco-
types of the grasses are found on ore outcrops
containing extremely high amounts of metals1.
Crops vary widely in their susceptibility to
different toxic elements7*1"-''412. The early work
of Hewitt2" with several toxic metals and recent
work of Page ct «/.'' with Cd in nutrient solution
can not easily be extrapolated to soils.
Celery is known for its unusual tolerance to
excess Cu44; however, it is as sensitive to Zn and
Ni as most vegetables41. Metal tolerant grass
ecotypes developed tolerance only to the metals
in excess in the soils on which the ecotypes were
growing'. The 1:2:8 ratio for the relative toxicity
of Zn:Cu:Ni used in the Zn(equivalent) factor is
only an average of the relative tolerance for
many crops. The apparent relative tolerance of
crops will vary in different soils depending upon
the levels of O.M., PO4, and pH which control
the relative toxicity of Zn vs Cu or Ni. Crops
also differ in the accumulation of metals in their
leaves or edible parts.
The root is the metal-sensitive organ in plants.
Excess Zn, Cu, and Ni reduce root yield more
than top yield. Chlorosis caused by Zn, Cu, or
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132
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Ni is actually the result of reduced Fe transport
by roots. Metal analysis of roots has been pro-
posed to demonstrate toxic metal injury because
the root prevents much of the toxic metal from
reaching the leaves14. A synergistic toxicity,
where the combined effect of Zn ;md Ou is worse
than the sum of the injury from separate Zn and
Cu treatments, probably may be reasonably esti-
mated only from root analysis because of the ef-
fects these metals have on each other's transport
to leaves. Assays for varietal difference to toxic
metals invariably have shown the root to be the
best indicator organ.
The root also appears to be the site of PO4 in-
terference with both toxic metal injury and
transport. In studying toxic metals in sludge and
effluent, the simultaneous presence of excess PO4
produces a situation where little of the available
literature can be meaningfully applied. PO4 has
already been mentioned as inhibiting Fe trans-
port and interacting with Cu and Ni which also
produce Fe deficiency4".
Danger To the Food Chain
from Toxic Metals
Toxic metals added to soils are not a hazard to
the food chain until they have entered an edible part
of a plant—leaf, grain, fruit, or edible root or tuber.
Some direct ingestion of recently applied metals4, or
of soil containing large amounts of metals will be a
special hazard to animals grazing sludge- or effluent-
treated sites.
The elements that are a significant potential hazard
to the food chain through plant accumulation are Cd,
Cu, and Zn.
Very high amounts of Cr3+added to soil do not in-
crease the Cr contents of crops appreciably, and con-
stitute no hazard. Boron, Co, and Ni at levels that se-
verely injure the plant, present no threat to the food
chain. Mercury from sludge will increase soil Hg
levels, but the increase in plant Hg will be small
(Tables 3, 4, 5, and 6). Hg does not appear to consti-
tute the food-chain accumulator in agriculture that it
does in the oceans. Pb is not translocated readily to
plant tops, and is especially excluded from grain,
fruits, and edible roots (Tables 3, 4, 5, and 6). The
lack of Pb accumulation appears to be related to the
presence of the high amount of PO4 in sludge and ef-
fluent.
Underwood"' summarized much of the available
information on Zn and Cu excesses in animal nutri-
tion. The more sensitive animals suffer from Zn toxi-
city if the diet contains between 500 to 1000 ppm as
Zn sulfate. Plants that contain 1000 ppm Zn or more
are usually severely injured, and would show eco-
nomically damaging yield reductions; however, the
data in Table 2 conflict with the data of
Boawn & Rasmussen". Because yield usually is re-
duced at lower plant Zn levels than those that injure
the animal that consumes the plant, the food chain
appears to be protected. Available information on
toxicity to animals from Zn in food crops is insuffi-
cient to establish a safe plant Zn level.
Cadmium is somewhat like Zn in that increases in
soil Cd from sludge or effluent can lead to increased
food chain Cd. The Food and Drug Administration
expects to eventually specify the permissible level of
Cd in foods in the marketplace. The only apparent
way to be sure that the Cd in a food crop grown on a
sludge- or effluent-treated soil will not be a potential
food-chain hazard is to reduce the Cd content of
sludges to 0.5 percent of the Zn content, and as near
as possible to 0.1 percent of the Zn content (Table 7).
TABLE 3
Effect of Sludge On Toxic Elements In Corn'
Element
Soil
Available1
Corn
Leaves
Corn
Gram
Cd, ppm
Zn, ppm
Cd/Zn, %
Cu, ppm
Ni, ppm
Pb, ppm
Hg, ppb
0
0.22
13.
1.7
3.9
2.3
6.6
44.
44
7.0
181.
3.9
32.
7.0
30.
273.
1 Data of Hinesly, Jones, and Ziegler2'
20 1 N HCI extractable, April 1971.
'April 1970.
0
3.3
58.
5.7
8.9
2.8
7.1
27.
Tons Sludge!A3
44
11.6
212.
5.5
8.7
4.3
6.3
38.
0
0.30
89.
.34
5.2
23
.025
5.2
44
1.03
152.
.68
5.6
3.1
.028
3.6
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
133
TABLE 4
Effect of Sludge On Toxic Elements In Corn'
Element
Soil Content
Corn grain
182
182
Cd, ppm
Zn, ppm
Cd/Zn %
Cu, ppm
Ni, ppm
Pb, ppm
Hg, ppb
2.4
69.
3.5
20.
40.
36.
10.
98.7
1679.
5.9
483.
115.
361.
1392.
0.8
36.
2.2
16.
3.8
7.0
19.8
11.7
232.
5.0
16.
4.0
3.5
26.0
.07
20.
.35
6.
20
1.5
2.0
.29
31.
.93
6.
2.7
044
24
'Data of W. J. Bauer'
;ChicagivWSW lagixmed digested sludge- SKMC'O
TABLE 5
Effect of Sludge On Toxic Elements In Soybeans'
Element
Soil Content
Soybean Leave*
Ton sludgel/A. 7"
Soybean dram
Cd, ppm
Zn, ppm
Cd/Zn, %
Cu, ppm
Ni, ppm
Pb, ppm
Hg, ppb
0
3.0
91.
3.30
25.
50.
38
11
103
50.
873.
5.73
229
%
200
977
0
0.6
38.
1.58
15
8
4.5
62.
103
5.1
165.
3.09
18
13
4.0
28
0
.37
43.
0.86
16
5.7
2.0
2.8
103
2.0
114.
1.75
20
13.
1 8
3.2
'Data of W. J Bauer \
'Chicago WSW lagooned digested sludge SEMCO
TABLE 6
Effect of Sludge On Toxic
Elements In Fodder Rape'
TABLE 7
Cadmium and Zinc In Soils
Versus Crops
Soil Content
Element
Cd, ppm
Zn, ppm
Cd/Zn, 9f
Cu, ppm
Ni. ppm
Pb, ppm
Hg, ppb
Control
1 2
98.
1.2
26
28
26
18
Sludge1
1.7
369.
0.46
90.
43.
44.
675
Fodder Rape
Control
0.6
34.
1.8
3.9
4.9
5.2
33.
Sludge^
0.6
114.
0.52
8.3
9.2
7.7
49.
Sfitl
CttZn
%
8
1
0.5
0.1
'Ratio in en
Leaf Crop',1 drain.
CilZn
ppm
40500
5.500
2.5:500
0.5.500
JDS could double if soil at oH > 7
Fruit Root ( rop
-------
134
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
In this way, Zn excess (at about 500 ppm Zn in
leaves) would injure the crop before the Zn or Cd
content of the crop constituted a health hazard. Zn
appears to compete with Cd at the sites of uptake and
injury in animals, and the high Zn in crops grown on
sludge- and effluent-treated soil should serve to pre-
vent Cd injury. Many questions remain about what
levels of Cd vs Zn, absolute Cd level, etc., in crops
are safe for the human food chain. Controversy will
remain until experiments clarify the Cd and Zn rela-
tionships in natural food diets v,v injury to animals
throughout their Hfespan. The concept of Cd:Zn ratio
obviously is very important in evaluating the agricul-
tural movement of Cd into the food chain.
Copper will cause severe plant injury before the
content is high enough to be toxic to most animals.
However, sheep are very sensitive to plant Cu, and
some forages grown on soils enriched in Cu by sludge
or effluent could be toxic to sheep. When sludge is
sprayed on pastures, Cu is a special hazard (along
with Pb) until rain washes the Cu from the leaf sur-
faces.
Factors Affecting Plant Accumulation
of Toxic Metals
A.Any factor that affects the availability of the
toxic elements in the soil also affects the plant
accumulation. Thus, total amount of metal, pH,
O.M., PO4, C.E.C., and reversion control the
amount of excess metal available to the root. For
example, the effect of pH is seen in Zn and Cd
accumulation by crops (Tables 8 and 9). Many
experiments with excess metals have failed to in-
clude pH variables, so our knowledge of pH ef-
fect on metal accumulation is clearly insuffi-
cient. Organic matter may simultaneously lower
injury and increase accumulation because low
molecular weight chelates of Cu and Ni are
formed, which protect the root from severe
injury and stunting.
TABLE 8
Effect of Sludge Cd and Zn On
Cd:Zn Ratio In Corn1
0
11
22
44.1
Soil-'
I 7
37
39
3.9
(.'it Zn Knfio
Leaves
CillZn, 7<>
57
3.5
3.8
5.5
dram
0.34
0.6?
0.62
0.68
Grain
Leaves
6
18
16
12
Data of Hmesly, Jones and Ziegler '
April 1970. '01 N HC1 extractahle, Apr. 1971.
B.Characteristics of the toxic metal. In acid soils,
the elements Zn, Cd, and Mn are easily translo-
cated to plant tops. In strong contrast, Cu, Ni,
Pb, and Hg are translocated in appreciable
quantities only during severe injury to the plant.
Compare the results of Boawn and Rasmussen"
for Zn with the results of Roth et a/."1 for Cu
and Ni, and the results of Baumhardt and
Welch6 for Pb. Zn reaches >1000 ppm, whereas
Ni and Cu seldom exceed 70 ppm, and Pb is even
less.
C.Presence of competing ions. Cd and Zn competi-
tion was observed in the studies of Zn transport
by Hawf and Schmid1''. Some evidence of possi-
ble effects of sludge Cu on sludge Zn transport
by several crops is shown in Table 10. The lower
Zn content of leaves at low pH (5.5-6.0) than at
high pH (6.5-7.0) suggests that other toxic metals
can interfere with Zn transport.
D.Phosphate availability. Because PO4 is such an
important competing ion, it must be dealt with
separately. A great body of data is available on
the interference of PO4 with Zn, Cu, and Fe
metabolism of plants at deficient or marginal
levels of Zn, Cu, or Fe availability. Excessive
PO4 is also known to injure some plants. PO4
further appears to decrease the stunting injury
from toxic levels of Cu, Zn, and Ni. The work of
Spencer4" with Cu and P at toxic levels of Cu
(although confounded by uncontrolled pH
changes from the PO4 amendment) shows that
PO4 alleviates stunting and increases Fe-defi-
ciency chlorosis. The pattern should be the same
for Cu and Ni. Information is insufficient on the
effects of the excess PO4 added with sludge and
effluent on the toxicity and accumulation of Zn,
Cu, Ni, Cd, Pb, and Hg. Data also must be ob-
tained on the long-term effects, because both
metals and PO4 revert in the soil.
E. Rooting depth and soil distribution of metals.
The literature is replete with examples of soils
severely contaminated with Cu which support
good orchards and vineyards because their
perennial roots avoid the toxic zone. Chlorosis
of citrus from excess Cu occurred only when the
subsoil contained too little available Fe. When
these orchard soils are plowed and annual crops
planted, severe failure is often observed because
roots grow into the toxic zone.
Sludge can be applied in many ways (liquid
applied to surface, tilled and unfilled; filter cake
or sand bed sludge applied and mixed well or
left in chunks in the soil; covered trenches)
which lead to roots being able to avoid the toxic
metal zone, at least in the short run.
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
TABLE 9
Effect of pH On Seedling Corn Zn Content
Soil pH
5.0-5.2
5.4-5.6
6.0-6.2
6.4-6.6
7.0-7.2
Control
34
29
22
14
12
131 Zn
Treatment1
5%
5% Peat 5% Sludge
64 Cu Peat + 131 Zn + 64 Cu
ft-g Zn/g dry matter
1116
916
594
231
101
25
22
18
13
251
140
149
92
486
318
163
144
'luka srl subsoil; Crystal Lake peat; Baltimore digested sludge, Wf 9 x 38-11 seedling
corn.
Corn
Soybean
Tomato
Mustard
Sugarheet
Chard
Rye
Wheat
Fescue
655
444
628
1500
1369
1270
228
194
260
TABLE 10
Effect of Digested Sewage
Sludge (Five Percent)1 On
Zn Content of Several
Crops at Two pH's
Leaf Zn content ug/g dry weight
Crop Low pH High pH
295
222
335
660
1193
1330
296
272
301
'Five percent Baltimore digested sewage sludge added 186
ppm Zn and 66 ppm Cu to Evesboro loamy sand soil.
F. Plant age and seasonal effects. The age of a leaf
affects its Zti and Cd contents, and probably its
Cu, Ni, Pb, and Hg contents. As shown in Tables
11 and 12, the oldest leaves of plants supplied
toxic levels of Zn contained much more Zn than
the youngest leaves. The growth rate of some
crops allows a dilution in leaf Zn and Pb as the
season progresses: seedlings >ear leaves >mature
stover. Crops differ widely in this behavior;
monocots do not appear to concentrate Zn in
older leaves as most dicots do. Chard accumu-
lated as much as 1900 ppm Zn and 90 ppm Cu
during the season with no symptom of injury.
Lead accumulation in many crops shows a
strong seasonal influence" *. Seasonal effects on
Pb accumulation by crops grown on sludge- or
effluent-treated soils apparently remain un-
examined. It would appear that winter pasture
could be a hazard, whereas spring and summer
pasture would remain low in Pb.
G.Plant species and variety; grain vs forage. Plant
species and varieties differ in toxic metal accu-
mulations. The work of Boawn7 with Zn, Hunter
and Vergnano22 with Ni, etc., demonstrate these
differences. Few reports have been published on
crop differences in accumulation of toxic metals
in edible portions when grown on sludge- or ef-
fluent-treated soils.
At excess levels, the grain, fruit, or edible root
of many crops contains two- to tenfold lower
levels of Zn than the leaves. Thus, corn grain
from a sludged site could contain less toxic
metals than mixed pasture or silage. Whether
the relative exclusion of toxic metals by grasses
would allow more nutrient removal, yet safer
levels of Zn, Cd, and Pb, than growth of corn
grain is unclear. A further advantage of grain
crops vs leaf crops is the two- to tenfold greater
exclusion of Cd relative to Zn during grain fill-
ing (Tables 3, 4, 5, and 8).
Some have suggested that we should breed
varieties of crops that can tolerate and exclude
undesired toxic elements. Although more toler-
ant varieties probably could be developed, only
an effort to produce metal-tolerant perennial
grasses that would exclude toxic elements seems
reasonable. This would allow maintenance of an
economic crop on sites dedicated to receive
sludge or effluent until other economic crops
will no longer tolerate the soil toxic metal levels.
H.Soil moisture, aeration, and temperature. Any of
the physical factors that affect plant growth and
absorption of ions will affect accumulation of
toxic metals. Essentially no information is avail-
able on effects of temperature and oxygen on up-
take or transport of toxic metals. These factors
may also affect reversion and soil adsorption of
the toxic metals.
-------
136
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 11
Effect of Leaf Age On Zn Content
Added Cd
ntf>/k)>
1.31
131
131
Soil
PH
6.4
5.3
6.4
Leaf Number
Caline
47
4457
1114
1st, 2nd
3rd, 4th
52
2817
757
Cd/g dry weight
45
2208
637
Younger
50
1493
405
TABLE 12
Effect of Leaf Age On Cd Content
Ailt/ftl Cil
1.31
1.31
Stnl
I'll
6.3
6.4
/,<•(// Niunhi'r
53.3
19.7
267
10.4
4(l\
20.8
6.7
11.3
33
Cadmium and Zinc in Soils,
Crops, and Food Chain
As mentioned earlier, it appears that the permissi-
ble Cd content of foods in the marketplace may be
established at the current natural background levels.
We will have to live within these restrictions or show
that they are invalid. Although there are substantial
arguments against the suggested toxicity of Cd at low
levels in foods'"2", we will have to control the level of
Cd in agricultural products to meet these food stand-
ards. Little or no information is available on the
movement of Cd from feed grains or pasture into
beefsteak; this part of the Cd cycle is still completely
open. Thus, we need to quickly obtain information on
Cd movement from sludge and effluent to foods.
Several studies on land application of sludge have
reported the Cd and Zn contents of the crops grown.
The work by Hinesly et a/.21, Table 3, and Bauer5,
Tables 4 and 5, used the Chicago WSW sludge, which
contains high levels of Cd (six to eight percent of Zn),
and should not be considered as representative of
what can be expected with acceptable levels of Cd
(<0.5 percent of Zn). Table 8 summarizes the Cd and
Zn data of Hinesly et a/.21: Cd is left behind during
grain filling. Comparison of corn and soybeans sug-
gests that exclusion of Cd during grain filling is less
pronounced in soybeans than in corn. There may be
varietal differences as well. Table 13 shows the effect
of soil pH on Cd:Zn ratio in the previously described
chard experiment.
How do we solve the Cd problem in land applica-
tion of sludge and effluent? First, we can prevent
sludges and effluents with a high Cd:Zn ratio (»0.5
percent) from reaching soil. Cd is generally a specific
pollutant and is easily removed from wastewater to
10 fig/ 1 at the industrial plant. I have discussed the
role of Cd:Zn ratio in sludge-~plant leaves—grain,
fruit, or edible root movement of Cd (see Table 7).
We can devise situations where sludge and effluent
application will lead to a net decrease in Cd move-
ments into the food chain, //the Cd:Zn ratio in ap-
plied materials is <0.5 percent and as near as possible
to 0.1 percent.
Numerous studies are in progress on Cd accumula-
tion by crop plants. When information becomes
available on the effect of food Cd and Zn on animal
uptake of and injury by Cd during life-term studies,
perhaps we can make more valid judgments. Now, we
can only conclude that if we control the Cd:Zn ratio
so that when Zn is injuring the crop enough that the
farmer will lime or change crops to prevent injury
from Zn, that the Cd content will not be a hazard by
FDA regulatory standards; hence, the <0.5 percent Cd
of the Zn content.
TABLE 13
Zn:Cd Ratio In Chard Leaves
Added Zn
ppm
1.31
32.7
65.4
131.
262.
53
1.90
1.56
1.24
0.96
1.00
Soil pH
64
Cd/Zn <%)
0.69
1.68
1 87
1.26
1.24
72
5 31
2.16
2.49
203
2.09
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
137
Benefits of Zn and Cu In Sludge
and Effluent
The micronutrients Zn and Cu are often deficient
or marginally sufficient in agronomic soils. This re-
sults in low levels of Zn in crops and thus less Zn is
available in the diet of animals. Because many people
do not, or will not, supplement their low Zn diet, we
must find some way to increase food Zn. Recent re-
ports show that some teenagers' diets are low or defi-
cient in Zn and clinical Zn-deficiency symptoms have
been observed1'. Zn and Cu in sludge or effluent can
be considered fertilizers when they correct deficien-
cies (including that induced by the excess PO4 added
with sludge). Fiskell et al.14 and Parsa34 found sludge
to be an excellent Cu or Zn fertilizer. Most soils
could be improved by adding a little sludge with its
beneficial N, P, O.M., Zn, and Cu. Thus sludge could
lead to higher crop Zn levels (at least in leaf crops)
and thereby help to correct the problem of low Zn in
the food chain.
Current Recommendations
I feel that there are two bases for recommenda-
tions for toxic metals to be added to agricultural
soils as sludge or effluent. These are: (1) Benefitrrisk
ratio, and (2) limitation of metal additions to permit
continued general farming.
The benefits of sludge and effluent include water,
O.M., N, PO4, Zn, and Cu. Risks include the toxic
metals which should be minimized wherever possible.
Table 14 shows the reasonably attainable (in 1973)
minimum toxic metal content. Higher than minimum
Cd, Co, Cr, Ni, Pb, Hg, and B contents are a result of
industrial pollution. Zn and Cu in digested sludge
probably will never drop below 500 and 200 ppm, re-
spectively. The metal content shown in Table 14 rep-
resents an attainable, reasonable, toxic metal content
for digested sludge, and hence a good benefit:risk
ratio for land application. Sludges and higher toxic
metal contents should not be applied to agricultural
land. These criteria (except the Cd:Zn ratio) need not
apply to dedicated disposal sites not used to grow
crops for sale.
If the composition of a sludge meets the above rec-
ommendation, our next consideration is to limit toxic
metal additions to levels which permit continued gen-
eral farming on the amended soil even after the added
O.M. is gone and an equilibrium of metals and PO4
has been reached. Because lowering the soil pH be-
low 6.5 leads to extensive increase in toxic metal
availability to plants, some assumption has to be
made about the pH of the amended soils. Thus, I pre-
sume that the toxic-metal-amended (sludge or efflu-
ent) soil used for food crops will be maintained at pH
6.5 or above.
TABLE 14
Metal Content of
a Sludge Appropriate
for Land Application
Element
Zn
Cu
Ni
Cd
B
Pb
Hg
Content
< 2000 ppm
< 800 ppm
< 100 ppm
< 0.5 % of Zn
< 100 ppm
< 1000 ppm
< 15 ppm
Chumbley1' recommended that no more than 250
ppm Zn equivalent of toxic metals be added to soils
(at pHi6.5) in any 30-year period. This recommenda-
tion did not account for any of the important soil
variables except pH. Leeper25 suggested that we
could add toxic metals up to five percent of the
C.E.C. (at pH 6.5). The five percent of C.E.C. figure
would still allow appreciable injury to metal-sensi-
tive crops at pH 5.5. At pH >6.5, the Zn and Cu
would only serve as fertilizers.
Thus, I believe that toxic metal additions to agri-
cultural soils should not exceed Zn(equivalent) levels
equal to five percent of the C.E.C. of the unamended
soil (at pH-6.5). When our knowledge of the rever-
sion process, of O.M. disappearance, of PO4 effects,
and of metal interaction increases, this limit may like-
ly be set higher. With our present knowledge, five
percent of C.E.C. appears to be sufficient to protect
our agricultural soil resources.
Many of these recommendations relate to applica-
tion of sludge. Table 15 presents the 1972 Water
Quality Criteria for irrigation water and estimation of
toxic element accumulation in soils. Based on cri-
teria, metals may accumulate to toxic levels.
-------
138
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 15
Water Quality Criteria, 1972:
Irrigation Water
Element
Maximum
mg/1
Estimated soil balance after 100 years
Accumulation1 Removal1
Ib/A ug/g % of
Ib/A Added
B
Cd
Co
Cu
Pb
Mo
Ni
Zn
0.75
0.010
0.050
0.20
5.0
0.010
0.20
2.00
1 From 3 acre-ft/ acre/ year.
!Corn grain at 167 Bu/A.
History of Metal Toxicity
There are numerous examples of metal toxicity in
agriculture. Toxic amounts of Cu, Zn, or Ni have ac-
cumulated in soils from fungicides, unneeded fertil-
izers, and sewage sludge, or have occurred naturally.
Most toxicities have occurred under intensive agri-
cultural practices, such as orchards, vineyards, or
vegetable fields, and can be quite expensive to allevi-
ate. Delas12 and Reuther and Smith37 have summar-
ized much of this information. These results seldom
can be related to disposal of sludge or effluent be-
cause of the high O.M. and PO4 in land application
sites.
Metal toxicity from field application of sludge and
effluent has been observed in England35 and other
areas. These toxicities to crops generally have oc-
curred in unmanaged situations most favorable for
toxicity: low pH, sandy soils, high metal sludges,
and/or metal-sensitive crops. These toxicities have
often been alleviated by liming to higher soil pH.
However, one of Patterson's examples, a "market gar-
den in Somerset," involved an organic soil with very
high metal content. In this case, the only choice was
to stop growing sensitive crops. This case also relates
to Leeper's example of destruction of O.M. over a
period of years.
The available reports are very difficult to interpret
because the information is so sparse. To interpret re-
ports on metal toxicity, we need data on soil pH,
C.E.C., O.M., total and available Zn, Cu, Ni, Cd, Pb,
PO4, and toxic metal contents of crops grown in
comparison with control treatments. The "Woburn
Market Garden Experiment" with sewage sludge was
lost by plowing for 20 years27 and no meaningful in-
formation was obtained except a warning to look
600
8
40
160
4000
8
160
1600
10
0.2
1.0
10
0.05
0.5
5.
200
1.7
2.5
2.5
6.2
6.3
3.1
12.5
harder at toxic metals. RohdeV8 report does not in-
clude plant analysis and other information needed to
interpret his observations.
Until we have more field knowledge of toxic ele-
ment injury and accumulation from sludges and efflu-
ents, we will not be sure we are dealing with all of the
potential problems. Lunt28 and Anderson' warned of
toxic metals. Experiments in progress in the U.S.,
England, and Sweden are attacking these questions
and should provide the information needed to set
firm guidelines to protect soils and the food chain.
Major Questions Remaining
A.The extent of crop species and varietal differen-
ces in tolerance to and accumulation of toxic
metals. The effect of season (as with Pb) and
plant part (leaf vs grain) on toxic metal entry to
the food chain.
B.We know far too little about Cd movement from
soil to edible plant part to food in the market-
place.
C.We know very little about the nature and per-
manence of reversion of toxic metals in different
soils; effects of Fe, Mn oxides, silicate, O.M.,
PO , etc.
D.We need more basic knowledge on crop and
management effects on soil O.M. as it relates to
control of available excess Cu, Ni, and Zn.
E.We know almost nothing about toxic metal in-
teractions (synergistic toxicity) and the impor-
tance and mechanism of PO interaction with
Zn, Cu, Ni, Cd, Pb, and Hg to alleviate toxicity
and prevent plant transport of these toxic ele-
ments.
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
We especially know little about the above in actual
field practice. Study of ongoing, older, land applica-
tion of sludge and effluent sites would significantly
complement the current laboratory, greenhouse, lysi-
meter, and field studies of these practices.
LITERATURE CITED
I. Anderson, M. S. "Sewage Sludge for Soil Im-
provement." USDA Circular 972, 27 pp. 1955.
2. Anderson, A. and K. O. Nilsson. "Enrichment of
Trace Elements from Sewage Sludge Fertilizer In
Soils and Plants." Ambio, 1:176-179. 1972.
3. Antonovics, J., A. D. Bradshaw, and R. G. Turn-
er. "Heavy Metal Tolerance In Plants." Adv. Ecol.
Res.. 7:1-85. 1971.
4. Batey, T., C. Berryman, and C. Line. "The Dis-
posal of Copper-enriched Pig-Manure Slurry On
Grassland." J. Br. Grassld. Soc.. 27:139-143. 1972.
5. Bauer, W. J. Heavy Metals In Soils and Crops.
Volume 4. Soil Enrichment Materials Corporation,
Chicago, 111. 1972.
6. Baumhardt, G. R. and L. F. Welch. "Lead Up-
take and Corn Growth with Soil-Applied Lead." J.
Environ. Qual., 1:92-94. 1972.
7. Boawn, L. C. "Zinc Accumulation Character-
istics of Some Leafy Vegetables." Commun. Soil Sci.
Plant Anal.. 2:31-36. 1971.
Boawn, L. C. and P. E. Rasmussen. "Crop Re-
sponse to Excessive Zinc Fertilization of Alkaline
Soil." Agrim. J.. 63:874-876. 1971.
9. Brown, A. L., B. A. Krantz, and P. E. Martin.
"The Residual Effect of Zinc Applied to Soils." Soil
Sci. Soc. Amer. Proc., 28:236-238. 1964.
10. Chapman, H. D. Diagnostic Criteria for Plants
and Soils Univ Calif Div. Agr. Sci. 1966.
11. Chumbley, C. G. "Permissible Levels of Toxic
Metals In Sewage Used On Agricultural Land."
A DA.S. Advisory Paper No. W. 12 pp. 1971.
12. Delas, J. "The Toxicity of Copper Accumulat-
ing In Soils. Agro-chimica, 7:258-288 (in French).
1963.
13. Fiskcll, J. G. A., P. H. Everett, and S. J.
Locascio. "Minor Element Release from Organo-N
Fertilizer Materials In Laboratory and Field
Studies." ./. Ag. Food Chem., 12:363-367. 1964.
14. Fiskell. J. G. A. and C. D. Leonard. "Soil and
Root Copper. Evaluation of Copper Fertilization by
Analysis of Soil and Citrus Roots." J. Agr. Food.
Client., 15-350-353. S967.
15. Follett, R. H. and W. L. Lindsay. "Changes In
DTPA-Extractable Zinc, Iron, Manganese, and Cop-
per In Soils Following Fertilization." Soil Sci. Soc.
Amer Proc.. 35:600-602. 1971.
16. Fulkerson. W and H. E. Goeller (Eds). Cad-
mium the Dissipated Element. Oak Ridge Natl. Lab.
NSF-FP-21 513 pp. 1972.
17. Gadgil, R. L. "Tolerance of Heavy Metals and
the Reclamation of Industrial Waste." J. Appl. Ecol.
6:247-259. 1969.
18. Hambridge, K. M., C. Hambridge, M. Jacobs
and J. D. Baum. "Low Levels of Zinc In Hair,
Anorexiz, Poor Growth and Hypogeusia In Chil-
dren." Pediat. Res., 6:868-874. 1972.
19. Hawf, L. R. and W. E. Schmid. "Uptake and
Translocation of Zinc by Intact Plants." Plant and
Soil. 27:249-260. 1967.
20. Hewitt, E. J. "Metal Interrelationships In Plant
Nutrition: I. Effects of Some Metal Toxicilics On
Sugarbeet, Tomato, Oat, Potato and Marrowstem
Kale Grown In Sand Culture." ,/. i.xpi. Hot, 4:57-69.
1953.
21. Hinesly, T. D., R. L. Jones and E. L. Ziegler.
"Effects On Corn by Applications of Heated An-
aerobically Digested Sludge." Compost Sci.. 13'26-30.
1972.
22. Hunter, J. G. and O. Vergnano. "Nickel Toxic-
ity In Plants." Ann. Appl. Hiol., 39:279-284. 1952
23. King, L. D. and H. D. Morris. "Land Disposal
of Liquid Sewage Sludge: I. The Effect On Yield, In
Vivo Digestibility, and Chemical Composition of
Coastal Bermudagrass (Cynodon dactylon L. Pers). ./.
Environ. Qual., 1:325-329. 1972.
24. King, L. D. and H. D. Morris. "Land Disposal
of Liquid Sewage Sludge: II. The Effect On Soil pH,
Manganese, Zinc, and Growth and Chemical Com-
position of Rye (Secale cereale L.)" J. Environ. Qual.,
1:425-429. 1972.
25. Leeper, G. W. Reactions of Heavy Metals with
Soils with Special Regard to Their Application In Sew-
age Wastes. Department of the Army, Corps of Engi-
neers Under Contract No. DACW73-73-C-0026. 70
pp. 1972.
26. Lener, J. and B. Bibr. "Cadmium Content In
Some Foodstuffs In Respect of Its Biological Ef-
fects." Vitalstoffe Zi vi lisations-krankhe it en,
15(4): 139-141. 1970.
27. Le Riche, H. H. "Metal Contamination of Soil
In the Woburn Market-Garden Experiment Resulting
from the Application of Sewage Sludge." ./. Agr. Sa ,
71:205-208. 1968.
28. Lunt, H. A. "The Case for Sludge as a Soil Im-
prover with Emphasis On Value of pH Control and
Toxicity of Minor Elements." Water Sewage Works.
11:295-301. 1953.
29. Mann, H. H. and T. W. Barnes. "The Perman-
ence of Organic Matter Added to Soil." J. Agr. Sci.,
48:160-163. 1957.
30. Miller, R. H. and D. D. Zaebst. "Factors Af-
fecting the Rate of Sewage Sludge Decomposition In
Soils." Agron. Abstr., 1972:98. 1972.
31. Mitchell, R. L. and J. W. S. Reith. "The Lead
Content of Pasture Herbage." J. Sti. Fd. Agric.,
17:437-440. 1966.
-------
140
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
32. Ng, S.-K. and C. Bloomfield. "The Effect of
Flooding and Aeration On the Mobility of Certain
Trace Elements In Soils." Plant &Soil, 16:108-135.
1962.
33. Page, A. L., F. T. Bingham, and C. Nelson.
"Cadmium Absorption and Growth of Various Plant
Species as Influenced by Solution Cadmium Concen-
tration." J. Environ. Qual., 1:288-291. 1972.
34. Parsa, A. A. "Solid Wastes as Zn Fertilizers."
Ph. D. Thesis. Colorado State University. 47 pp. 1970.
35. Patterson, J. B. E. "Metal Toxicities Arising
from Industry." Trace Elements In Soils and Crops.
Min. Agr. Fish. Food Tech. Bull., 21:193-207. 1971.
36. Rains, D. W. "Lead Accumulation by Wild
Oats (A vena fatua) In a Contaminated Area." Nature,
233:210-211. 1971.
37. Reuther, W. and P. F. Smith. "Toxic Effects of
Accumulated Copper In Florida Soils." Soil Sci. Soc.
Fla. Prot:, 14:17-23. 1954.
38. Rohde, G. "The Effects of Trace Elements on
the Exhaustion of Sewage-Irrigated Land." J. fnst.
Sew. Purif., 1962:581-585. 1962.
39. Roth, J. A., E. F. Wallihan, and R. G. Sharp-
less. "Uptake by Oats and Soybeans of Copper and
Nickel Added to a Peat Soil." Soil Sci., 112:338-342.
1971.
40. Spencer, W. F. "Effect of Copper On Yield and
Uptake of Phosphorus and Iron by Citrus Seedlings
Grown at Various Phosphorus Levels." Soil Sci.,
102:296-299. 1966.
41. Underwood, E. J. Trace Elements in Human
and Animal Nutrition. Third Edition. Academic
Press, New York. 1971.
42. Walsh, L M., D. R. Steevens, H. D. Seibel, and
G. G. Weis. "Effect of High Rates of Zinc On Several
Crops Grown On an Irrigated Plainfield Sand." Com-
mun. Soil Sci. Plant Anal.. 3:187-195. 1972.
43. Webber, J. "Effects of Toxic Metals In Sewage
On Crops." Water Pollut. Control, 71(4):404-413.
1972.
44. Westgate, P. J. "Preliminary Report On Copper
Toxicity and Iron Chlorosis In Old Vegetable
Fields." Proc. Fla. St. Hon. Soc., 65:143-146.
45. Williams, C. H. and D. J. David. "The Effect of
Superphosphate On the Cadmium Content of Soils
and Plants." Aust. J. Soil Res., 11:43-56. 1973.
DISCUSSION
QUESTION: Tom Hinesly, Office of the Under-
secretary of the Army. I just wanted to ask Dr.
Chancy if he considered how much land would be
needed for the disposal of all the sludges that are
produced in the United States, and just how big a fac-
tor this is from the standpoint of the food chain9
According to my calculations and what some of the
other speakers have said about reasonable and safe
rates, we are only talking about less than ten million
acres of land as compared to 465 million acres. 1 also
wondered what you might have to say about the use
of this from a standpoint of reclaiming strip mine
lands which contain some of these metals in higher
concentrations than are found in sludges?
ANSWER: We have looked at your estimates
Tom. The ten million acre estimate. And that is pre-
suming the attitude of continual, inperpctuity
disposal on those ten million acres. If we took sludges
as they are today, instead of the 500 /,inc and 200
copper that they can be, we would use those ten
million acres up before a century was gone. Which
ten million do we take the next century and then cen-
tury after that'?
Strip mines. It is clear from everybody's work now,
including some of our own, that the high amount of
phosphate we add as sludge is very important at
curing the already existing metal toxicity of strip
mines. Usually we raise the pH at the same time. They
are going to be no better when the organic matter is
decayed to the climatic equilibrium and any other
soil, and if we add a thousand or ten thousand or
what ever ppm zinc, and the copper and nickel and
cadmium that go along with it, we are going to have
the same problem because somebody is going to do
something with that site. Somebody is going to bring
the question up about the wildlife on the dedicated
land at the Chicago site, that we can't eat anything we
shoot on that site. Somebody is going to bring that up
and I think we have to accept that responsibility too.
QUESTION: William Bauer, Bauer Engineering,
Chicago. In relation to the philosophy of using a site
as a relatively permanent place to park heav> metals,
have you given any consideration to the reclaiming of
those heavy metals through a mining operation. The
reason I mentioned that to you the other day, Rufus, I
described how we already got almost seven thousand
pounds per acre in the upper seven inches of soil in
our Arcola Project, and we plan to go to maybe
twenty thousand pounds per acre and that stuff might
be worth maybe an average of 30 or 40 cents a pound,
so, we would have quite a bit of metal there. I know
from our lab work that we can reclaim some of this. I
was just wondering if you gave any consideration to
that?
ANSWER: We have talked about it enough to
know that the cost of reclaiming it, there is an awful
lot left at the factory, that some factories can actually
make money by reclaiming their metal waste and par-
ticular things like cadmium and some of the other
-------
CHAIN EFFECTS OF TOXIC ELEMENTS
141
semi-value metals. If they are claimed at the factory,
they usually dump right back into their process so
they can be sold as reclaimed, relatively pure metal.
By the time it reaches the sewerage plant, it becomes
almost inseparable. And then it is only if it is so toxic
that it shouldn't be put on land in the first place
unless it is dedicated land. Leaper mentioned, "let's
put it on land and then shove the top foot away and
start again." It is a good idea for dedicated land, not
for farm land.
QUESTION: William Bauer, Bauer Engineering,
Chicago. I would agree with you for the ongoing
work, but we do have a lot of accumulated sludges
that we already have on hand, that have a lot of
metals in them and there isn't anyway to deal with
those.
ANSWER: If the site could become a food chain
hazard we can't put it on land. There is a represen-
tative from Food and Drug who addressed this
question in the workshops in particular, and I think
that that really needs to be saved because it is another
half an hour discussion.
-------
Crop Selection
and Management
Alternatives
—Perennials—
WILLIAM E. SOPPER
Penn State University
INTRODUCTION
The purpose of this paper is to present an over-
view of our current state of knowledge concerning
the use of perennials as the vegetative cover on sites
to be used for the disposal of treated municipal sew-
age effluent and/ or sludge. An attempt will be made
to briefly review what has been reported in the litera-
ture on the subject and to point out gaps in our cur-
rent state of knowledge and areas of needed research.
Hopefully, this review will set the stage and provide a
point of departure for discussions in the Workshop on
Soil-Nutrient Relationships & Crop Selection and
Management.
Selection of the vegetative cover to be utilized or
established and maintained on a spray irrigation site
depends upon many factors. The following are some
of the criteria which should be considered:
1. Water requirements and tolerance
2. Nutrient requirements and tolerance
3. Optimum soil conditions for growth
4. Season of growth and dormancy requirements
5. Sensitivity to toxic heavy metals and salts
6. Nutrient utilization and renovation efficiency
7. Ecosystem stability
8. Length of harvesting rotation
9. Insect and disease problems
10. Natural range
11. Demand or market for the product
The obvious primary choice one has is between a
perennial agricultural crop and forest vegetation.
The advantages and disadvantages of each will be
discussed.
Agronomic Crops
Perennial grasses appear to be the most suitable
for wastewater disposal sites and have received the
most attention. In general, they have fiberous root
systems, are sod forming which aids in erosion con-
trol and provides for high infiltration rates, are toler-
ant of a wide range of ecological conditions, have a
long period of growth and have a high uptake of nu-
trients. Results of investigations with reed canary-
grass at the Penn State Project will be cited as an
example of using a perennial grass in a land manage-
ment system.
Crop Yields and Renovation Efficiency
An area of reed canarygrass was irrigated with
treated municipal sewage effluent at two inches per
week from 1965 to 1969 and with a combination of
effluent and liquid digested sludge in 1970. During
the six years, yields varied from 4.32 to 7.03 tons per
acre. More important, however, is the nutrient con-
tent and the amount of nutrients removed in the har-
vested crops. Under the "living filter" concept of
land disposal the higher plants growing on the site are
an integral part of the system and assist the microbio-
logical and physio-chemical activities occurring
within the soil to renovate the wastewater. The con-
tribution of the vegetative cover to the renovation
process adds durability to the system. Average nutri-
ent composition and quantities of nutrients removed
by reed canarygrass during 1970 are given in Table 1.
It is readily evident that substantial amounts of nutri-
ents can be removed in the harvested crop. These
143
-------
144
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
amounts are considerably greater than that removed
by row crops, particularly in respect to nitrogen. For
instance, the harvest of corn silage irrigated at the
same level during the same year removed only 160
pounds of nitrogen and 43 pounds of phosphorus.
The amounts of nutrients removed annually by the
grass will vary with the amount of wastewater ap-
plied, amount of rainfall, length of the growing sea-
son, and the number of cuttings.
TABLE 1
Average Nutrient Composition
and Quantities of Nutrients
Removed by Reed Canarygrass
Irrigated with Two Inches of
Effluent During 19707
Nutrient
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
Average Nutrient
Composition
3.69
0.50
2.23
0.40
0.36
1.57
309
Total Amount
Removed
Pounds per acre
408.2
56.0
246.9
44.2
40.4
158.4
3.4
0.09
The efficiency of the crop as a renovating agent
can be assessed by computing a "renovation effi-
ciency" expressed as the ratio of the weight of the nu-
trient removed in the harvested crop to the weight of
the same nutrient applied in the wastewater.
During the six year period, 2127 pounds of nitro-
gen were applied to the reed canarygrass area in 536
inches of sewage effluent and sludge. A total of 2071
pounds were removed in the harvested crop resulting
in a renovation efficiency of 97.3 percent.
During the same period of time, 797 pounds of
phosphorus were applied in the wastewater and 279
pounds removed in crop harvest for an overall reno-
vation efficiency of 35 percent. Annual renovation
efficiencies varied from 24 to 63 percent. Hence, it is
obvious that some other process than utilization of
the vegetative cover must be used to assure the re-
moval of this key eutrophic nutrient. This additional
renovation and removal of phosphorus is usually ac-
complished by way of the large withholding capacity
of most agricultural soils for phosphorus.
Nutrient Balances
Phosphorus and nitrogen balances were calculated
for the reed canarygrass area and are given in
Table 2.
After six years 797 pounds of phosphorus and 2127
pounds of nitrogen had been applied to each acre.
Harvested crops removed 279 pounds of phosphorus.
Since the concentration of phosphorus in the perco-
late at the four foot soil depth was only 0.05 mg/ 1
and was no greater than that in an unirrigated adja-
cent forest area, the net percolation losses of phos-
phorus from the wastewater treated areas were as-
sumed to be proportional only to the excess perco-
lation induced by the added wastewater. Further,
since precipitation always exceeds potential evapo-
transpiration on an annual basis, the wastewater was
assumed to be totally recharged. On the basis of these
assumptions, the net percolation loss of phosphorus
from the wastewater irrigated areas was calculated to
be 6.4 pounds per acre during the six year period, or
only 0.8 percent of the amount applied. Thus, the soil
with its strong absorptive capacity for phosphorus,
together with the crop harvests, has persistently re-
moved 99.2 percent of the added phosphorus.
Nitrogen removals by the soil and crop system
have also been equally efficient. Over the six year
period 2127 pounds of nitrogen were added to each
acre. Protein removed in the harvested reed can-
arygrass was equivalent to 2071 pounds of nitrogen
TABLE 2
Phosphorus and Nitrogen Balances for Reed
Canarygrass Irrigated with Effluent at Two Inches
Per Week During the Period 1965 to 19707
Period
1965-70
Amount Applied
Wasterwatef Nutrient
inches
536
Ibs/ acre
797(P)
2127(N)
Removed
By Crop By Leaching
Ibs/ acre
279(P)
2071(N)
Ibs/ acre
64(P)
452(N)
Retained
By Soil
lb&/acre
5I2(P)
-396(N)
-------
PERENNIALS
145
per acre. Kjeldahl nitrogen content of the upper foot
of soil was approximately 5000 pounds per acre.
Average concentration of nitrate-N in the percolate
at the four foot soil depth during the six-year period
was 3.5 mg/1 in the effluent irrigated areas and 0.2
mg/1 in the control areas. On the basis of the same as-
sumptions used above, the excess percolate from the
S36 inches of wastewater applied per acre would have
carried a total of 452 pounds of nitrogen into the
groundwater. This quantity is 396 pounds in excess of
the 56 pounds per acre difference between the
amount of nitrogen added in the wastewater and the
amount removed in the harvested crops and could
easily have been derived from the large amounts of
native soil nitrogen. Thus the reed canarygrass was
effective in removing 97.3 percent of the added
nitrogen.
Wastewater Renovation
The overall effectiveness of the perennial grass
management system to accept and renovate waste-
water is shown by the decrease in average nutrient
concentration in percolating water. The mean annual
concentrations of phosphorus at three soil depths are
shown in Table 3. After six years, (1965-70), the aver-
age concentration of phosphorus was only 0.038 mg/1
indicating a 98.9 percent decrease in the average con-
centration. The efficiency of the perennial grass sys-
tem is further demonstrated by the fact that the reed
canarygrass area received 180 inches more waste-
water than an adjacent corn silage area and average
phosphorus concentration at the 6-inch depth was
only 0.161 mg/1 in comparison to 0.138 mg/ 1 on the
corn area.
Mean annual concentrations of nitrate-nitrogen at
three soil depths are given in Table 4. It is similarly
obvious that the reed canarygrass system was equally
efficient in maintaining NO3-N levels below the 10
mg/1 limit recommended for drinking water.
In summary, it appears that there is sufficient evi-
dence to indicate that perennial grass management
TABLE 3
Mean Annual Concentration of Phosphorus
in Suction Lysimeter Samples at Three
Depths and in the Applied Wastewater in
the Reed Canarygrass Area Receiving Two
Inches of Wastewater Weekly from 1966 to 19707
Lysimeter
Depth
inches
6
24
48
1966
0.164
0.091
0.055
1967
0.128
0.110
0.053
1968
0.218
0.120
0.052
1969
concentration - mg/1
0.186
0.089
0.035
7970
0.161
0.067
0.038
Wastewater
7.690
7.695
8.450
4.185
3.490
TABLE 4
Mean Annual Concentration of
Nitrate-Nitrogen in Suction Lysimeter
Samples at Three Depths in the Reed
Canarygrass Area Receiving Two Inches
of Wastewater Weekly During the Period
1966 to 19707
Ly\inu'lcr
Depth
inches
6
24
48
1966
0.8
2.2
37
1967
0.6
1.5
3.3
I96N
1969
cunt entnition - ni^/
0.7 0.6
1.8 1.1
31 25
1970
1.2
0.8
2.4
-------
146
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
systems-are adaptable to municipal wastewater dis-
posal sites, that increased crop yields can be achieved
and that the wastewater can be satisfactorily reno-
vated. There, are however, still some unanswered
questions relative to the grazing of livestock on dis-
posal sites and the feeding of forage to livestock.
There is little documentary evidence on the nutrition-
al adequacy of sewage effluent and sludge produced
forage, possible toxicity problems associated with ef-
fluent residues on vegetation or accumulation of ele-
ments in vegetation, or potential parasitic infections
of cattle grazing on wastewater irrigated pastures.
Forests
Forests and brushland often receive high priority
as potential areas for wastewater disposal because
they usually occupy rural areas and land values are
relatively low in comparison to highly productive
agronomic areas. The use of forests for wastewater
disposal has not been extensively studied. Several
projects are currently underway but little informa-
tion has yet been published to provide the necessary
data for decision making and design purposes relative
to land disposal projects under the varying soils and
climatic conditions in the various forest regions of
the United States.
Treated municipal sewage effluent has been spray
irrigated in forested areas for a ten year (1963-1972)
period at the Penn State Project. The results of this
research will be used to illustrate the relative merits
of a forest management system. Forested areas irri-
gated consisted of a mixed hardwood forest, a red
pine plantation I Finns resinosa), and a sparse white
spruce (Picca glauca) plantation established on an
abandoned old field. Detailed descriptions of these
areas have been previously reported by Sopper"'.
Sewage effluent was applied in various amounts
ranging from 1 inch per week to six inches per week
and over various lengths of time ranging from 23
weeks during the growing season to the entire 52
\\ceks. Rate of application was 0.25 inch per hour.
Wastewater Renovation
Nitrogen and phosphorus are the two key eu-
trophic elements in municipal sewage effluent and
therefore discussions on renovation will be limited to
these two elements.
The forested areas were highly efficient in remov-
ing phosphorus. During the past ten years, the aver-
age concentration of phosphorus in the effluent
sprayed on the land, ranging from 0.5 to 10 milli-
grams per liter (mg/ 1). The forest biosystem was able
to decrease the phosphorus concentration by more
than 90 percent at the two-foot soil depth under all
application rates. During the tenth year (1972), the
average concentration of phosphorus in the effluent
was 4.505 mg/ 1. This concentration was diminished
to values ranging from 0.037 to 0.200 mg/ 1 at the
four-foot soil depth indicating renovation percent-
ages from 95 to 99 percent in the various forested
areas. In control areas the percolating water at the
same soil depth had phosphorus concentrations rang-
ing from 0.035 to 0.113 mg/ I. These values are not
very different from the effluent-irrigated plots con-
sidering that up to 50 feet of sewage effluent had been
applied over the ten-year period.
The efficiency of the forest areas to reduce nitro-
gen concentrations has been variable. Average an-
nual concentrations of nitrate-nitrogen in soil water
percolate samples collected at the 48-inch depth are
given in Table 5.
It is clear that the forested areas can handle a one-
inch per week application without having the mean
annual concentration of nitrate-nitrogen at the 48-
inch depth exceed the Public Health Service limit.
However, when two inches were applied per week
either in the April-November period with red pine on
the Hublersburg clay loam soil or year-around with
hardwoods on the Morrison sandy loam soil the
NOrN concentration at the 48-inch depth rapidly
exceeded the Public Health Service limit. On the
other hand, two inches of wastewater applied weekly
on the old field area on the Hublersburg clay loam
soil in the April-November period did not result in
excessive NOrN values at the 48-inch depth.
The difference between the two-inch red pine and
two-inch old field areas on the same soil type prob-
ably resides in the difference in the recycling of the
nitrogen through the two vegetative covers. In the red
pine, relatively less nitrogen is assimilated in the an-
nual growth than in the herbaceous annuals and
perennials in the old field and larger amounts of
readily decomposable organic residues are deposited
annually in the old field. The larger quantities of car-
bonaceous material in the old field area may also
promote a higher degree of denitrification in this fine
textured soil. The sandiness of the Morrison soil on
the two-inch hardwood area would not be conducive
to denitrification of the larger nitrogen load applied
in a year-around irrigation period and the hardwood
leaf litter although more decomposable than the red
pine needle litter would not be as decomposable as
the old field residues.
The explanation above was corroborated when the
two-inch red pine area was clearcut after many of the
trees were felled by a heavy wet snow and windstorm
in November, 1968. After the clearcutting the area
grew up to a dense cover of herbaceous vegetation
similar to that on the irrigated old field area. A large
mass of carbonaceous was deposited on the surface in
the fall of 1969 and in 1970 another dense cover of
herbaceous vegetation was produced and the mean
-------
I'KRKNNIALS 147
TABLE 5
Mean Annual Concentration (mg/1) of Nitrate-Nitrogen in Suction Lysimeter Samples
Collected at the 48-Inch Soil Depth in Forest Areas Receiving Various Levels of
Wastewater During the Period 1965-19707
Red Pine
HnbUnhiiri! Soil
inches per week
1 2
Hardwood
Hiihlcnhurf! Soil
inches per week
0 1
Old Field
Hublcrstntrx Soil
inches per week
0 2
Hardwood
Morrison Soil
imhes per week
0 2
Ihd'lenhnii;
inears at rates of one inch and two inches per week
iluring the growing season (April to November). The
plantation was established in 1939 with the trees
planted at a spacing of eight by eight feet. In 1963 the
average tree diameter at breast height was 6.8 inches
and average height was 35 feet.
Diameter and height growth measurements were
made annually. Average annual growth for the period
I9o3 to 1970 is given in Table 6. Irrigation with sew-
age effluent at both rates produced slight increases in
height growth during the first two years. This slight
increase in height growth has been maintained on the
plot receiving one inch per week. However, on the
plot receiving two inches per week, height growth
continually decreased up to 1968 when high winds
following a wet snowfall completely felled every tree
on the plot.
Diameter growth was measured annually with
dendrometer bands. In addition increment cores were
taken m 1972 from sample trees in all areas. The ac-
tual measurements of average radius growth taken
from the increment cores indicate that the previous
diameter growth data reported which was based upon
dendrometer band measurements of tree circumfcr
ences was incorrect1'. Average annual diametei
growth based on increment core nieasur menls is
given in Table 7. Irrigation at the one-inch-per-week
level increased the average annual diameter growth
by 183 percent. On the other hand, the two-inch-per-
week level actually caused a reduction in diameter
growth. In addition, during the sixth year of irriga-
tion the needles of the pines being irrigated at the
higher rate began to turn yellow. This result was not
TABLE 6
Average Annual Terminal Height
Growth of Red Pine Irrigated
with Sewage Effluent
Avenge Annual
HeixlH dri/wth
feel
I X
I 4
1 6
1.7
Irrigated - 1 inch per week
Control
Irrigated - 2 inches per week
Control
TABLE 7
Average Annual Diameter Growth of
Red Pine Irrigated with
Sewage Effluent
Treatment
Irrigated - 1 inch per week
Control
Irrigated - 2 inches per week*
Control
/heraxc Annual
Diameter Growth
inches
017
0.06
0.06
007
* For period 1963 to 1968 only
-------
148
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
totally unexpected since other investigators have re-
ported red pine growth to be adversely affected on
wet soils and to be sensitive to boron toxicity. Ap-
proximately four pounds of boron per acre are
applied annually in the sewage effluent. Other in-
vestigators have previously reported that applications
of 1.1 pounds of boron per acre were sufficient to in-
duce city symptoms.
White Spruce. Two experimental plots were
established in a sparse white spruce plantation on an
abandoned old-field area. The trees in 1963 ranged
from three to eight feet in height. One plot has been
irrigated with sewage effluent during the past ten
years at the rate of two inches per week, while the
second plot has been maintained as a control. Height
growth measurements have been made annually. In
1972, all tree diameters were measured and increment
cores taken to determine the average annual diameter
growth.
Total height of the trees were measured in August
1972. Average height of the trees on the irrigated plot
was 20 feet and ranged from 12 to 25 feet. The aver-
age height of the trees on the control plot was nine
feet and ranged from 8 to 15 feet. Over the ten-year
period average annual height growth was 18 inches
on the irrigated areas and five inches on the control
areas, representing a 360 percent increase as a result
of sewage effluent irrigation.
Average diameter of trees on the irrigated plot was
3.7 inches in comparison to 1.1 inches on the control
plot. Measurements taken from increment cores indi-
cated that the average annual diameter growth on the
irrigated trees was 0.40 inch and on the control trees
0.18 inch, representing a 122 percent increase.
Mixed Hardwoods. A hardwood forest, consisting
primarily of oak species, was irrigated with sewage
effluent at rates ranging from one inch to four inches
per week and for periods ranging from the growing
season (23 weeks) to the entire year (52 weeks). Prin-
cipal species were white oak (Qucrcits alha). chestnut
oak «J pnnm), black oak (Q. wlutina), red oak (Q.
nihni). scarlet oak (Q. coccincu). red maple (Acer
nihriim), and hickory (Carya spp.).
Average annual diameter growth during the 1963
to 1972 period is given in Table 8. One inch per week
applications produced only slight increases in di-
ameter growth; however, the two- and four-inch-per-
week levels results in 69 and 40 percent increases, re-
spectively. These values pertain primarily to the oak
species. Some of the other hardwood species present
on the plots have responded to a greater extent. For
instance, increment core measurements made on red
maple (A. rubrum) and sugar maple (A. saccharum),
indicate that the average annual diameter growth
during the past ten years has been 0.43 inch on the
trees irrigated with one inch of effluent per week in
comparison to 0.10 inch on control trees, a 330 per-
cent increase in average annual diameter growth.
Similarly, increment core measurements made on
aspen (Populus tremulodies) irrigated with two inches
of effluent weekly during the growing season indi-
cated that the irrigated trees had an average annual
diameter growth of 0.47 inch in comparison to 0.24
inch for unirrigated trees, a 96 percent increase in
growth. Saplings which averaged 0.65 inch in
diameter in 1963 increased in diameter to an average
of 5.3 inches on the irrigated areas by 1972 in com-
parison to 3.1 inches on the control areas.
TABLE 8
Average Annual Diameter Growth
in Hardwood Forests
Irrigated with Sewage Effluent
Wct'klv Irrigation Average Dmnn'tcr (iruwiti
Amount ( oiiirol liriniili'fl
inches inch inch
I1 0.16 018
2* ' 0.13 0.22
4' ' ' 0.15 0.21
* Irrigated with one inch of sewage effluent weekly during
growing season from 1963 to 1972.
* * Irrigated with two inches of sewage effluent weekly during
the entire year from 1965 to 1972.
* * * Irrigated with four inches of sewage effluent weekly dur-
ing the growing season only from 1963 to 1967; during the dorm-
ant season only from 1968 to 1971, and with two inches of efflu-
ent weekly during the growing season in 1972
Renovation Efficiency
The nutrient element content of the foliage of the
vegetation on the irrigated plots was consistently
higher than that of the vegetation on the control
plots. It is therefore obvious that the forest vegetation
is contributing to the renovation of the percolating
effluent; however, its order of magnitude is difficult
to estimate because the annual storage of nutrients in
the woody tissue and the extent of recycling of nutri-
ents in the forest litter are extremely difficult to
measure. Although considerable amounts of nutrients
may be taken up by trees during the growing season,
many of these nutrients are redeposited annually in
leaf and needle litter rather than being hauled away
as in the case of harvested agronomic crops.
A comparison between the annual uptake of nutri-
ents by an agronomic crop (silage corn) and a hard-
wood forest is given in Table 9. It is obvious that trees
are not as efficient renovating agents as agronomic
crops. Whereas harvesting a corn silage crop re-
moved 145 percent of the nitrogen applied in the
-------
PERENNIALS
TABLE 9
Annual Uptake of Nutrients by a Silage Corn Crop
and a Hardwood Forest Irrigated with Two Inches
of Effluent Weekly During 1970
Nutrient
N
P
K
Ca
Mg
Com
Pa. 602-A
llVacre
16!
42
129
27
23
Renovation
Efficiency *
145
143
130
15
27
hori-M
Ibs/acre
84
K
26
22
5
39
19
22
9
4
* Percentage of the element applied in the sewage effluent that is utilized removed by the vegetation
sewage effluent, the trees only remove 39 percent
most of which is returned to the soil by leaf fall. Simi-
larly only 19 percent of the phosphorus applied in the
sewage effluent is taken up by trees in comparison to
143 percent of the corn silage crop.
Wood Fiber Quality
A review of the literature indicates that numerous
studies have been made concerning forest fertilization
and forest irrigation but only a few studies have been
made concerning the combined effects of fertilization
and irrigation on forest tree growth. Moreover, al-
most no data is available on the effects of municipal
wastewater irrigation on the anatomical and physical
properties of the wood of forest trees. The results of a
recent study by Murphey et. al.4, provides some in-
sight along these lines for the species red pine and
red oak.
They reported that sewage effluent irrigation on
red pine resulted generally in increased specific grav-
ity, increased tracheid diameter, decreased cell wall
thickness, and no change in tracheid length.
Positive changes also occurred in the red oak wood
due to irrigation with sewage effluent. They reported
a five percent reduction in the earlywood vessel seg-
ment diameter. These large barrel-shaped elements
are the causes of "picking"—the lifting of the surface
of paper during printing. The smaller, longer cells
produced by effluent irrigation might reduce this
problem when using ring porous woods such as red
oak for pulp. An increase in the number and height of
broad rays resulted in an increase in the amount of
wood volume occupied by the broad rays from nine
percent in the untreated xylem to 11.5 percent of the
wood laid down during irrigation. The increase in
number and height of broad rays would cause an in-
crease in the percentage of "fines" in a pulp mix. In-
crease m specific gravity and particularly in the
change in the amount of latewood from about one-
half to three-quarters ot the growth ring provides
more mass of fibers per unit volume. Coupled with
the growth rate change, irrigation with municipal
wastewater results in the development of more fiber
per treated tree. The increase in fiber and vessel seg-
ment length also increased the utility of this wood tor
pulp Wangaard and Williams' have shown a rela-
tionship exists between fiber and length and tear
strength for known paper sheet densities and fiber
strength. The longer the fiber the stronger the paper
for a given fiber strength below a critical sheet
density.
Murphey et. al.', concluded that in general the al-
terations of the wood fibers resulting from waste-
water irrigation enhanced their utilization as a raw
material for pulp and paper.
Ecosystem Stability
Ecosystems are somewhat elastic and can with-
stand a certain amount of stress prior to permanent
change or collapse. Weekly application of wastewater
will certainly impose a stress on the ecosystem. An
unresolved question is whether the impact will be suf-
ficient to cause a significant change and whether the
change will be desirable or undesirable. Regular ap
plications of large volumes of wastewater can turn a
relatively dry site into a moist super-humid site anil a
relatively sterile site into a fertile one. Such changes
may influence species composition and plant density
on the site as well as fungi, bacteria, and microor-
ganism types and populations. These changes, in turn,
may influence the habitat and utilization of the site
by wildlife. In general these changes are subtle and
occur over a long period of time. Since there are no
municipal wastewater spray irrigation projects in the
United States older than ten years on which the eco-
systems have been monitored annually, we can only
conjecture the long term effects. Some of the results
from the Penn State Project will illustrate some of the
trends observed during the past decade.
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ISO
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Forest Reproduction
A mature mixed hardwood forest was irrigated
with sewage effluent at the rate of one inch per week
during the growing season from 1963 to 1972. Meas-
urements made on milacre plots in 1972 indicated a
drastic reduction in the number of tree seedlings
present in the irrigated area. The initial survey in
1964 indicated about 15,800 tree seedlings per acre in
the control area with a slight reduction to 13,600 in
1972. However, in 1964 (the second year of irriga-
tion) there were 14,500 tree seedlings per acre present
in the irrigated area and only 1,830 in 1972. No con-
clusive evidence is yet available to explain these re-
sults. Soil sample analyses and climatic data are cur-
rently being evaluated for a possible explanation.
These results may be partially due to the fact that ef-
fluent irrigation stimulates leaf growth which pro-
duces a more dense canopy and reduces light inten-
sity at the forest floor. Average light intensity under
the canopy in the irrigated area was less than 50 per-
cent of that under the control plot canopy.
A similar reduction was also found in the number
of herbaceous plants in the irrigated forest area. The
initial survey in 1964 indicated about 86,333 stems
per acre, whereas in 1972 there were only 14,800
stems per acre. On the control area, the 1964 survey
indicated 63,170 stems per acre in comparison to
25,000 stems per acre in 1972.
Old Field Herbaceous Vegetation
An old field area consisting primarily of proverty
grass (Danthonia spicata), goldenrod (Solidago spp.)
and dewberry (Rubus flagellaris) was irrigated with
sewage effluent at the rate of two inches per week
during the growing season from 1963 to 1972. Signifi-
cant changes have been observed in species composi-
tion, vegetation density, height growth, dry matter
production, percentage areal cover, and nutrient uti-
lization.
Average dry matter production during the ten-year
period was 5457 pounds per acre on the irrigated plot
and 1810 pounds per acre on the control plot. This
represents an average annual increase of 201 percent.
Annual increases ranged from 100 to 350 percent.
Several species which were predominant prior to
wastewater irrigation have been drastically reduced
in number or have disappeared completely. For in-
stance, goldenrod (Solidago spp.) which had 155,090
stems per acre in 1963 was reduced to 13,612 stems
per acre by 1972. White Aster (Aster piloxus) which
had 122,970 stems per acre in 1963 was not present
on the site in 1972. The predominant species on the
irrigated plot was clearweed (Pilea pumila L.) which
covered more than 80 percent of the plot with ap-
proximately 19 million stems per acre. This species is
typical of shaded moist sites.
Species composition changes are illustrated in
Table 10 based on measurements made in 1972. The
control plot is representative of pre-irrigation vegeta-
tion conditions.
The average height of the predominant plant
species on the irrigated plot was five feet in compari-
son to one foot on the control plot. While the irri-
gated plot had a complete dense vegetative cover ap-
proximately ten percent of the control was barren of
vegetation.
TABLE 10
Predominate Herbaceous Vegetation Species on the Irrigated
and Control Plots of the Old Field Area in 19727
Species
Goldenrod (Solidago juncea)
Aster (Aster spp.)
Dewberry (Rubus flagellaris)
Strawberry (Fragaria vesca)
Poverty grass (Danthonia spicata)
Everlasting (Antennaria spicata)
Goldenrod (5. rugosa. S. graminifolia, S. juncea)
Milkweed (Asclepias rukra)
Indian Hemp (Apocynum cannahinum)
Night shade (Solanum dulcamara)
Clearweed (Pilea pumila)
Irrigated Plot
Percent Average
Cover Height
\
0
0
5
0
0
5
5
5
10
75
feet
2.8
09
5.3
5.1
3.3
2.3
1 5
Control Plot
Percent
Cover Height
5
5
40
10
20
5
0
0
0
0
0
feet
1.8
1 I
08
05
03
01
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I'KRKNNIALS
Wildlife Habitat
As mentioned previously spray irrigation of muni-
cipal wastewater over large areas of forest, brush-
land, or perennial weeds will certainly affect the
value of the site in terms of wildlife habitat. Here
again there is a dearth of information. Wildlife stud-
ies were only initiated on the Penn State Project in
1^71 and. hence, the results obtained to date are
largely inconclusive. Wo
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152
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
There are more than three million acres of dis-
turbed land in the United States which might be re-
stored to a more aesthetic and productive state
through applications of municipal sewage effluent
and sludge.
Operation—Annual or Seasonal
The use of perennials in the land management sys-
tem of the disposal site may depend upon whether
spray irrigation will be continued throughout the
year or only operated during the warm summer grow-
ing season. If annual spray irrigation is contemplated,
forests or perennial grasses may have to be used,
particularly in the northern climates where tem-
peratures drop and remain below freezing for pro-
longed periods of time. These vegetation types will
normally provide better winter infiltration conditions
because of the accumulation of organic matter which
provides an insulation layer on the soil surface and
reduces soil freezing. In addition, the acid conditions
generally associated with forest soils provide a larg-
er phosphorus adsorptive capacity.
Management Problems
Utilization of perennial vegetation on the spray ir-
rigation site generally necessitates the use of a solid-
set irrigation system. Some of the potential problems
to be encountered can be eliminated through proper
design of the irrigation system.
For instance, if a perennial grass is to be used and
harvested for silage, the distance between lateral lines
should be sufficient to provide access and turning of
harvesting equipment. Alternate disposal areas must
be available to accept wastewater during the period
allowed for field conditions to dry prior to harvest.
Three potential problem areas may be encountered
in forested areas. These are (1) ice damage, (2) wind-
throw, and (3) tree injury by sprinkler spray.
With winter irrigation a certain amount of ice
damage must be expected. A survey in a mixed hard-
wood forest on the Penn State Project following win-
ter irrigation indicated that approximately 52 stems
per acre showed visible ice damage in the irrigated
area compared to 7.5 stems per acre in the control
area. Seventy-five percent of these trees were in the
two-inch diameter class. The species most susceptible
to ice damage was red maple. It is quite possible that
extensive ice damage could effect stand reproduction
and alter species composition. Ice damage can be
somewhat minimized through the proper design of the
spray irrigation system and the use of non-rotating
sprinkler or low-trajectory rotating sprinklers.
A survey was also made in 1972 in the same forest
stand to determine if ten years of sewage effluent irri-
gation had any effect on tree mortality. Mortality be-
ing defined as standing dead trees above 1.0 inch in
diameter. There appeared to be no difference in the
amount of mortality in the irrigated and control areas
(104 versus 106 trees per acre, respectively).
In dense forest stands or coniferous plantations
bark damage and tree injury can be extensive if sprin-
kler nozzle pressures are too high. Wide lateral line
spacings which require high sprinkler nozzle pres-
sures for proper effluent distribution are not applic-
able if the forest condition is to be perpetrated. La-
teral line spacings should be selected so as to permit
the use of sprinkler nozzles pressures of approximate-
ly 50 psi. This, of course, will result in an increased
capital cost for the irrigation system.
Windthrow of trees may also be a problem. Efflu-
ent irrigation at rates of one or two inches per week
may keep the soil moisture status near field capacity
and hence may encourage the development of shal-
low tree root systems. For instance, at the Penn State
Project in November 1968, following a weekly appli-
cation of two inches of effluent, a heavy snowfall ac-
companied by strong winds resulted in the complete
blow-down of a one-acre red pine plantation. Since
then several trees have also been wmdthrown in the
mixed hardwood forests. Most ol these trees were ad-
jacent to natural forest openings, agricultural fields
or power line rights-of-way. It appears that this prob-
lem could be minimized if an unirrigated buffer zone
50 to 100 feet wide were left on the windward side of
any irrigated forest area where exposed to an open
area. This buffer zone would provide a wind break
against prevailing winds.
SUMMARY
It appears that there is sufficient evidence to indi-
cate that perennial vegetation can be utilized as part
of the land management system of a municipal waste-
water disposal site. There is still, however, a need for
much definitive research data on almost all aspects
concerning the long-term environmental impacts on
the entire biosystem.
LITERATURE CITED
1. Kardos, L. T. and W. E. Sopper. 1973. Renova-
tion of municipal wastewater through land disposal
by spray irrigation. Symposium Proc. on Recycling
Treated Municipal Wastewater and Sludge Through
Forest and Cropland. University Press, The Penn-
sylvania State University (In Press).
2. Kudrna, F. 1971. Transporting and applying
treated sludge for land reclamation—Chicago's
"Prairie Plan." Proc. First Nat'l. Conf. on Compost-
ing—Waste Recycling, Rodale Press, Emmans, Pa.
pp. 60-62.
-------
I'KHKNNIALS
3. Lejchcr, T. R. 1972. Strip-mine reclamation uti-
li/ing treated municipal wastes. Proc. Watersheds in
Transition, Amer. Water Resources Assoc., Urbana,
111. pp. 371-376.
4. Murphey, W. K., R. L. Bisbin, W. J. Young and
B E Cutter. 1973. Anatomical and physical proper-
ties of red oak and red pine irrigated with municipal
uastewater. Sym. Proc. on Recycling Treated Muni-
cipal Wastewater and Sludge Through Forest and
Cropland. University Press, The Pennsylvania State
University (In Press).
5. Sopper, W. E. 1968. Wastewater renovation for
reuse: Key to optimum use of water resources. Water
Research,' Vol. 2:47-480.
6. Sopper, W. E. 1971. Effects of trees and forests
in neutralizing waste. In trees and forests in an urban-
i/ing environment, Coop. Ext. Service, Univ. of
Mass.. p. 43-57.
7 Sopper, W. E., L. T. Kardos. 1973. Vegetation
responses to irrigation with municipal wastewater.
Symposium proc. on Recycling Treated Municipal
Wastewater and Sludge Through Forest and Crop-
land. University Press, The Pennsylvania State Uni-
versity (In Press).
8. Sopper, W. E. and L. T. Kardos. 1972. Munici-
pal wastewater aids revegetation of strip-mined spoils
banks. Jour. Forestry 70(10): 612-615.
9. Wangaard, F. F. and D. L. Williams. 1970. Fiber
length and fiber strength in relation to tearing resist-
ance of hardwood pulps. TAPP1 53 (11):2153-2154.
10. Wood, G. W., D. W. Simpson and R. L. Dress-
ier 1973. Deer and rabbit response to the spray irri-
gation of chlorinated sewage effluent on wildland.
S\mp. Proc on Recycling Treated Municipal Waste-
water and Sludge Through Forest and Cropland, Uni-
versity Press, The Pennsylvania State University (In
Press).
DISCUSSION
QUESTION- Ray Harris, USDA, Forest Service 1
was kind of intrigued by the amount of damage you
had from irrigating with the sprinklers in winter
time. I know that you tried several other practical
methods which you dropped, but according to some
of the literature you wrote, I was just wondering with
the present uproar of clear cutting it you haven't re-
thought about using another irrigation method beside
sprinkling for winter?
ANSWER- We started our winter irrigation with
non-rotating type sprinklers in which a single shot of
waste-water came out, hit an inverted cone and then
distributed like an umbrella. You can eliminate a lot
of this winter breakage and damage with these The
only thing wrong with them is that you don't get a
very good distribution of effluent in the winter time
because it is all diverted out and it all comes off-like
on the end of an umbrella, so it is concentrated in a
little peripheral circle. So, in terms of renovation, it
is poor. So, we eventually, over a course of years,
went to rotating sprinklers of a type which did not
freeze up. They operate at low trajectory and we just
live with the amount of damage because we are, of
course, leaning towards the renovation aspects more
than the loss of the saplings at this point. You can't
go to furrow, you can't go to flooding in forest. I think
sprinkler irrigation solid set system in a forest is
about the only thing you could consider.
-------
Recycling
Urban Effluents
On Land
Using
Annual Crops
A. D. DAY
University of Arizona
ABSTRACT
Modern cities are faced with the problem of sewage
and waste disposal. Treated municipal wastewater has
been used for industrial purposes, for recreation, to
produce forest products and to grow agricultural crop
plants.
Since municipal wastewater contains more fertilizer
dements (nitrogen, phosphorus, and potassium) than
do most other forms of irrigation water, it offers a fu-
ture agricultural potential that should be exploited.
High yields of relatively high quality food, feed, for-
age, oil, and fiber plant products have been obtained
tmm crop plants utilizing municipal wastewater as a
source of irrigation water and plant nutrients.
Soil irrigated with wastewater had a lower infiltra-
tion rale, higher modulus of rupture, and more soluble
sails, nitrates, and phosphates than did soil irrigated
with well water and fertilized with suggested amounts
of nitrogen, phosphorus, and potassium. Irrigation
»it/i wastewater (sewage effluent) for 14 years did not
decrease field crop yields or result in any adverse ef-
fects on soil that could not be corrected with minor
changes in field crop culture,
INTRODUCTION
Wastewater (sewage effluent) from municipal and
industrial treatment plants is a potential source of ir-
rigation water and plant nutrients for agricultural
uses. Relatively few instances of agricultural uses of
wastewater in crop production have been recorded.
Most of the literature on this subject has been pre-
pared by scientists in the sewage disposal field. Agri-
cultural uses of wastewater aid crop production,
make beneficial use of water that would have been
wasted, decrease the pollutant load on receiving
streams and groundwater, and preserve normal
stream flow for downstream uses'1.
Literature Review
Research at Locations Other Than Arizona
Wastewater arising from domestic and industrial
use is unfit for further use without some treatment.
Even though the increase in solids content because of
use is small, it is the nature of the added material
rather than the amount that makes treatment neces-
sary. Advances in technology and in health sciences
have resulted in sewage treatment plants that produce
effluents thai are both safe and suitable for irrigation
of certain crops. The type of treatment by a sewage
plant determines the degree to which suspended
solids are removed from sewage. Primary treatment
by sedimentation may remove from 25 to 40 percent
of suspended solids. Additional treatment by trickling
filtration and secondary sedimentation or by the acti-
vated sludge process may remove as much as 95 per-
cent of the suspended solids. Chlorination of clarified
effluent from modern sewage treatment plants pro-
duces reclaimed water that is safe for many reuse ap-
plications. It is suited to agricultural applications due
to the soluble nitrogen and phosphates that remain
155
-------
156
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
after treatment. The quantities of these nutrient ma-
terials vary widely and should be determined for any
effluent considered for reuse. The application of
wastewater to agricultural land may serve two pur-
poses: (a) to promote plant growth and crop yields,
and (b) to further treat applied wastewater. Waste-
water must be adequately treated prior to use on agri-
cultural areas to avoid odor and other nuisance prob-
lems. Proper sanitary management dictates that the
constant flow of wastewater must be utilized at all
times. During periods of heavy rainfall and/ or when
crops are not being grown, it may be necessary to
provide adequate storage in lagoons or lakes to hold
the wastewater in reserve for periods when it can be
properly utilized by crops. Modern methods of irri-
gation management must be employed for the most
efficient use of the available supply. The water intake
rate and storage capacity of the soil profile must be
considered, along with the type of crop to be grown,
in determining the area required for the amount of
wastewater to be applied. Irrigation must be intermit-
tent and over-irrigation must be avoided if maximum
efficiency is to be achieved. Irrigation with waste-
water is normally practiced in areas where rainfall is
not sufficient during the growing season for maxi-
mum crop production14.
Muller" pointed out that settled and biologically
treated sewage was used to irrigate pasture crops and
fruit trees in Australia. Wierzbicki" reported that
groundwater supplies in Germany have been in-
creased by the utilization of sewage effluent for sur-
face irrigation. Hershkovitz and Feinmesser13 noted
that sewage effluent from secondary treatment facili-
ties in Israel was suitable for planned irrigation reuse.
Scarcity of water in southern Africa made the use of
sewage effluent for irrigation attractive and worthy of
consideration. Use of wastewater for agricultural and
horticultural purposes was good water and fertilizer
economy2.
Mitchell" reported that a sewage irrigation farm
had been in use since 1928 at Vineland, New Jersey.
The farm provided municipal sewage disposal facili-
ties for a population of 8,000 and irrigation with sew-
age effluent increased crop production on poor soils.
Travis'7 pointed out that Southern California's Tal-
bert Water District used effluent from the Orange
County Sanitary District's primary sedimentation
plant to irrigate 2,800 acres of crop land. Chapman1
noted that crop yields in Wisconsin were increased by
irrigation with water carrying effluent from city sew-
age disposal systems. Wells'8 reported that farmers
near San Antonio, Texas avoid drought by using
sewage plant effluent for the irrigation of about 4,000
acres of farm and pasture land.
Research Conducted in Arizona
Dye12 found that effluent from complete treatment
at the Activated Sludge Treatment Plant in Tucson,
Arizona contained considerable quantities of the
three principal fertilizer elements: nitrogen, phos-
phorus, and potassium.
The Arizona Agricultural Experiment Station,
University of Arizona, Tucson, has been conducting
preliminary research on the possible utilization of
treated municipal wastewater as a source of irrigation
water and plant nutrients in the production of crop
plants since 1957. Our research has involved the use
of wastewater (liquid effluent) from the Activated
Sludge Sewage Treatment Plant in Tucson, Ari/ona.
The treated municipal wastewater looked like ordi-
nary well water but it contained about 65 pounds of
nitrogen, 50 pounds of phosphate (P2O<,)- and 32
pounds of potash (K-,0) per acre-foot. It required
three acre-feet per acre of wastewater to grow a small
grain crop (barley, oats, and wheat) to maturity.
Local well water contained ten pounds of N, 0.5
pound of P2OS, and 14 pounds of K2O per acre-foot*1.
Four irrigation and fertilizer treatments were used in
our studies: (1) well water with no additional ferti-
lizer (check); (2) well water with suggested fertilizer
(100 pounds of N, 75 pounds of P2O<;, and 0 pounds of
K2O per acre); (3) well water with N, P2O5, and K2O
equal to wastewater (200 pounds of N, 150 pounds of
P2O^, and 100 pounds of K2O per acre); and (4)
wastewater with no additional water or fertilizer.
Experiments were conducted at Cortaro, Arizona
to compare the winter pasture forage production
from oats irrigated with municipal wastewater with
yields obtained when oats were irrigated with well
water and fertilized with different amounts of com-
mercial fertilizer. Plantings were made in December
and pasture forage was harvested at the jointing stage
of growth in March of the following year. The green
forage contained from 80 to 85 percent moisture.
Oats produced 150 percent more pasture forage when
grown on plots that received wastewater than when
grown with suggested amounts of well water and
commercial fertilizer'1. When oats pasture forage was
grown with wastewater, it contained approximately
the same amounts of protein and D.L.N. (Digestible
Laboratory Nutrients) as when it was irrigated with
well water and fertilized with nitrogen, phosphorus,
and potash from commercial fertilizers in amounts
equivalent to those supplied in wastewater1".
A local rancher used wastewater as the only source
of irrigation water and fertilizer to grow small grains
pasture forage for beef cattle. The pasture had a car-
rying capacity of four 500-pound steers per acre.
During the fall and early winter, the steers made an
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RECYCLING USING ANNUAL CROPS
157
average gain in weight of about one pound per steer
per day. In the late winter and early spring, the steers
made an average gain in weight of about two pounds
per steer per day. Beef gains of this magnitude com-
pare very favorably with gains obtained from small
grains winter pasture grown with regular irrigation
water and commercial fertilizer. The foregoing beef
gains were considerably higher than gains obtained
on the open range during the winter months. The ani-
mals drank wastewater instead of well water without
any detrimental effects6.
Very few instances of nitrate poisoning from small
grains forage have been verified in Arizona. How-
ever, excess nitrate accumulation may occur in plants
grown with high nitrogen fertilization under condi-
tions of limited moisture and low light intensity. The
danger of nitrate poisoning from small grains forage
grown with wastewater was no greater than the dan-
ger of nitrate poisoning from small grains grown with
well water and commercial fertilizer*.
Small grains (barley, oats, and wheat) provide ex-
cellent hay for beef and dairy cattle. They can be
grown during the summer in the cooler regions of the
United States and during the winter months in the
• mild areas of the Southwest. Hay production from
barley irrigated with wastewater was compared with
hay grown with well water and different amounts of
commercial fertilizer. Barley produced as much air-
dry hay when it was grown with wastewater as it pro-
duced when it was irrigated with well water and fer-
tilized with suggested commercial fertilizer. When
grown for hay production, barley appeared to be
more sensitive to the constituents in wastewater than
did oats or wheat'. Concentrations of protein and
D.L.N. in hay are measures of its livestock feed qual-
ity. When barley was grown with wastewater, it con-
tained more protein and D.L.N. than it contained
when it was irrigated with well water and fertilized
with nitrogen, phosphate, and potash from commer-
cial fertilizers in amounts equivalent to those sup-
plied sn wastewater''
High quality grain from barley and wheat is essen-
tial u-f profitable livestock feeding operations in the
Southwest. Studies were conducted in Arizona to de-
termiiij if municipal wastewater could be used suc-
cessfully as supplemental irrigation water to produce
high quality grain from barley and wheat. More grain
was produced on barley and wheat plots irrigated
wiih svastewatei than was obtained on plots that re-
ceived well water and N, P, and K in amounts equiva-
lent to those applied during the growing season in
wastewater. Barley and wheat utilized the nitrogen in
wastewater as efficiently as they used the nitrogen in
commercial fertilizer to produce high protein grain.
Wastewater had no undesirable effect on the D.L.N.
content of grain from barley and wheat".
Although it is possible to grow high yields of high
quality wheat grain for livestock feed with municipal
wastewater, the milling and baking qualities of wheat
grain produced with wastewater are lower than the
milling and" baking qualities of grain irrigated with
well water and fertilized with commercial inorganic
fertilizers'.
Studies were conducted in Arizona to determine ef-
fects of continued use of municipal wastewater, as a
source of irrigation water and plant nutrients, on se-
lected soil properties. The soil was a Grabe silt
loam. Barley, cotton, lettuce, and sorghum were
grown in rotation for 14 years. Soil irrigated with
only wastewater and no additional fertilizer was com-
pared with soil irrigated with well water and fertil-
ized with suggested amounts of nitrogen, ohosphorus,
and potassium. Soil irrigated with wastewater had a
lower infiltration rate, higher modulus of rupture,
and more soluble salts, nitrates, and phosphates than
did soil irrigated with well water. Irrigation with
wastewater for 14 years did not decrease field crops
yields or result in any adverse effects on Grabe silt
loam soil that could not be corrected with minor
changes in field crop culture.
What Is Not Known
Maximum and Optimum Wastewater
Irrigation Loads
The maximum amount of treated municipal waste-
water that may be applied to a given soil on which a
specific crop is being grown is not known. The ac-
ceptable load is usually determined by the quantity of
wastewater that can be used beneficially by a crop or
by the amount of fertilizer nutrients that can be as-
similated by a crop without detrimental effects. Ni-
trogen is usually the nutrient that limits the amount
of wastewater that can be used. Excessive nitrate con-
centration in groundwater may occur as a result of
overloading an irrigation system. Past experience has
shown that acceptable loadings range from two to
seven acre-feet of wastewater per year. Elemental ni-
trogen requirements for crop plants generally range
from 50 to 200 pounds per acre annually. The waste-
water irrigation load should be determined by the ir-
rigation needs and/ or the amount of plant nutrients
that can be utilized by the crops to be grown. The
elemental nitrogen content of treated municipal
wastewater ranges from 50 to 80 pounds per acre-
foot.
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158
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Regulation of Wastewater Supply
and Demand
Effective systems for the regulation of wastewater
supply and demand have not been developed. The
continuous supply of municipal wastewater through-
out the year must be stored and adjusted to the needs
of the crop plants to be grown in ways that will pre-
vent the pollution of underground water supplies.
The regulation of wastewater supply and demand will
be more difficult in the northern, humid regions than
it will be in southeastern and southwestern regions
where cropping systems can be developed that will
use some wastewater throughout the year.
Effects of Wastewater on Soil Properties
Effects of continued use of municipal wastewater
on specific physical, chemical, and biological proper-
ties of soil have not been thoroughly investigated. For
example, how does the continued use of wastewater
influence the nitrification rate, the mineralization
rate, and the mobility of phosphorus in the soil? Do
the biological effects of wastewater influence the
physical properties of soil and are some detrimental
effects balanced by beneficial effects?
Effects of Wastewater on Crop Yield
and Quality
Effects of continued use of wastewater on yield
and specific bio-chemical quality characteristics of
crop plants for human food and livestock feed are not
known. Yields and quality characteristics will vary
for different crops, cropping sequences, and rota-
tions The fiber, protein, amino acid, and digestible
nutrient content in plant materials determine their
relative food and/ or feed value.
Effects of Wastewater on Crop Variety
Adapted varieties of crop plants for continuous ir-
rigation with municipal wastewater are not known,
and have not been developed. New varieties of all
crop plants may have to be developed for the most
economical and efficient utilization of wastewater in
agriculture.
Future Research Suggestions
Maximum and Optimum Wastewater
Irrigation Loads
Research should be conducted to determine the
maximum and optimum treated municipal wastewater
irrigation loads for different soil types and different
crop plants.
Regulation of Wastewater Supply
and Demand
Effective systems for the regulation of municipal
wastewater supply and demand in specific areas and
for specific soils and specific crop plants need to be
developed.
Effects of Wastewater on Soil Properties
Studies to determine the effects of continued use
of municipal wastewater on specific physical, chemi-
cal, and biological properties of soil are needed.
Effects of Wastewater on Crop Yield
and Quality
The effects of continued use of municipal waste-
water on yield and specific biochemical quality char-
acteristics of crop plants for human food and live-
stock feed should be determined.
Crop Varieties for Wastewater Culture
Adapted varieties of crop plants for continuous ir-
rigation with municipal wastewater should be devel-
oped, using plant breeding techniques, for efficient
and economical utilization of wastewater in agricul-
ture.
SUMMARY
It is imperative that representatives from the
United States Environmental Protection Agency, the
United States Department of Agriculture, and the Na-
tional System of Land Grant Universities develop co-
operative and coordinated research programs that
will lead to the best possible recycling of municipal
effluents and sludges to the land. There are instances
where wastewater from municipal and/ or industrial
sewage plants was dumped into rivers and streams
and allowed to pollute these streams and in some
cases to pollute the underground water supply. This
discarded wastewater has a built-in agricultural po-
tential that can be used in the production of food and
feed from crops like corn and sorghum, high quality
forage from crops like alfalfa, special oils from crops
like safflower, and high quality fiber from crops like
cotton. Although numerous discarded materials in
our society are considered wastes today, many of
these materials can be effectively utilized in the days
ahead to provide the variety of foods needed to feed
our hungry world.
ACKNOWLEDGEMENTS
This report briefly summarizes past research on
the utilization of treated municipal wastewater as a
-------
RECYCLING USING ANNUAL CROPS
159
source of irrigation water and plant nutrients in agri-
culture. Only a few of the many contributors in the
field of wastewater research have been included in
the references listed in this report. To these contrib-
utors who have been cited and to all others who have
contributed to wastewater research in any way and
are not mentioned, I am deeply grateful.
REFERENCES
1. Chapman, C. J. "Pasture Fertilization with Sew-
age Effluent Irrigation." Compost Science 3(3):25,
1962.
2. Cormack, R. M. M. "Irrigation Potential of
Sewage Effluents." Jour. Inst. Serv. Purif. (British)
Part 3, p. 256-257, 1964.
3. Day, A. D. "Yield and Quality of Wheat Grain
Irrigated with City Sewage Effluent." 7964 Wheat
Newsletter II 39-40, 1965
4. Day, A D., J. L. Stroehlein, and T. C. Tucker.
"I-fleets of Treatment Plant Effluent on Soil Proper-
ties." Jour. Witter I'oll Control Fed. 44:372-375,
1972.
5. Day, A. D., and J. L. Stroehlein. Municipal
Wastewater and Soil Properties. American Society of
Agronomy, Agronomy Abstracts, p. 178, 1972.
6. Day. A. D., and T. C. Tucker. "Production of
Small Grains Pasture Forage Using Sewage Effluent
as a Source of Irrigation Water and Plant Nutrients."
Agron. J 51:569-572, 1959
7. Day, A. D., and T. C. Tucker. "Hay Production
of Small Grains Utilizing City Sewage Effluent."
Apron J 52:238-239, 1960.
8. Day, A. D., T C. Tucker, and M. G. Vavich.
"Nitrate Accumulation In Oats Pasture Forage Irri-
gated with Sewage Effluent." I960 Oat Newsletter
\ 1 29- 31. ! 9d I.
9 Day A D , T C Tucker, and M. G. Vavich.
"Effect of City Sewage Effluent On the Yield and
Quality of Grain from Barley. Oats and Wheat."
Agron. J 54.133-135, 1962.
10. Day, A. D., M. G. Vavich, and T. C. Tucker.
"Protein and Digestible Laboratory Nutrients In Oat
Pasture Forage Irrigated with City Sewage Effluent."
1961 () Newsletter 12:42-43. 1962.
11. Day, A. D., M. G. Vavich, and T. C. Tucker.
"Protein and Digestible Laboratory Nutrients In Bar-
ley Hay Irrigated with City Sewage Effluent." 1962
Barley Newsletter 6:66, 1963.
12. Dye, F. O. "Crop Irrigation with Sewage Efflu-
ent.' Sewge and Industrial Wastes 30:825-828, 1958.
13. Hershkovitz, S. "L , and A. Feinmesser. "Sewage
Reclaimed tor Irrigation in Israel Farm Oxidation
Ponds." Water I:ng 33:405. 1962.
14. Law, J. P., Jr. Agricultural Utilization of Sewuf.'.
Effluent and Sludge - An Annotated Bibliography
Federal Water Pollution Control Administration,
U.S. Dept. of Interior, CWR-2. 1968. 89p.
15. Mitchell, G. A. "Municipal Sewage Irrigation."
Engr. News-Record 119:63-66, 1937.
16. Muller, W. Irrigation with Sewage In Australia.
Wass. u. Boden 7:17. Water Poll. Abst. 29:202(1108),
1955.
17. Travis, P. W. Organizing a Sewage Effluent
Utilization Project. Public Works 91:119-120, 1960.
18. Wells, W. N. "Sewage Plant Effluent for Irriga-
tion. Compost Science 4(1): 19, 1963.
19. Wierzbicki, Jan. "Augmenting Water Supply
Sources Through Agricultural Utilization of Munici-
pal Sewage." Chiz. Wodd i Tech. Sanit. (Polish) 31:17.
Abst: Sewage and Ind. Wastes 29-1096, 1957
DISCUSSION
QUESTION. John Walker, USDA, Bcltsville You
said that when you irrigated with effluent you had n
yield, I think it was of oats, that was much greater
than when you gave it chemieal tertili/er and
nutrients and you didn't speculate as to why that was.
Why would that be? Do you know'7
ANSWER: A number of reasons have been
suggested for this. We at the University of Arizona
are not in 100 percent agreement by any rrcans as tc
how we should answer a question like that. We dc
feel that there are a number of constituents in waste-
water that we don't very often talk too much about
that probably have something to do with the response
that we received.
COMMENT' Al L. Page, University of California.
In response to the last comment regarding what this
could be due to. It very well could be due to trace
elements in the effluent as opposed to the lack of
trace elements in the irrigation water.
QUESTION: Darwin Wright, EPA. I would like to
ask Bill Sopper if he saw the same response in his
forests and 1 was wondering if this is it due to the
nutrients or whatever is in the sewerage or sludge or
is it due to the water itself7
ANSWER. I think it would just be both.
QUESTION: Jim Evans, USDA, Washington, D.
C. I believe that you made a statement that in ap-
plying sewerage effluent versus applying the
irrigation water and N-P-K, that you got a higher
quality food product, higher quality bread from the
fertilizer. Is this correct?
ANSWER: Yes, this is correct.
QUESTION: Jim Evans, USDA. Would you
speculate as to why this is true?
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160
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
ANSWER: One thing that was noted was that in
other numbered characteristics that go together that
they call milling quality. There are a number of
things that the miller does that he uses to determine
whether or not wheat A has what he would call good,
medium or poor milling quality versus say wheat B
and so on. So, as far as the general milling quality was
concerned, that wheat that was grown with regular
irrigation water and fertilized with N-P-K from com-
mercial sources, rated higher as far as general milling
qualities are concerned was that the cookie diameter
in some cases was a little greater when well water and
commercial forms of N-P-K was used than when
wastewater alone was used. In another instance I can
think of, I believe, the general loaf volume was a little
larger, a loaf was a little fluffier using conventional
culture over wastewater alone.
QUESTION: Jim Evans, USDA. Were these
significant differences?
ANSWER: In some cases they were. There were
some instances when they were not. I would have to
go back to the details. I would be glad to give them to
you if you want to see me afterwards or write me, but
in most cases they were real differences.
-------
Engineering and
Economics of
Sludge Handling
W. J. BAUER
Bauer Engineering, Inc.
INTRODUCTION
Sludges resulting from treatment of municipal
sewage are difficult to dewater so that transportation
and application problems begin with considerations
of just how much effort to expend on dewatering.
With a view to stimulating the thinking of engineers
concerned with the constructive use of this valuable
resource, this discussion is presented by a practicing
engineer who has been closely involved in excavating
and transporting over one million wet tons, and in
applying to land over a half million wet tons of
sludge slurry from the Metropolitan Sanitary District
of Greater Chicago. The sludge was transported by
unit train for distances up to 170 miles from Chicago.
Application was performed by several different tech-
niques, as will be discussed herein. Alternative trans-
portation systems are also discussed, including truck,
rail, barge, and pipeline.
Types of Sludges; Physical
Characteristics
Sludges can be primary or secondary, digested or
undigested, or various combinations. Although their
chemical and physical characteristics vary widely,
for purposes of this paper these variations will be
ignored.
The undigested sludges generally call for minimiz-
ing exposure of the sludge to reduce the possibility of
anyone being offended or believing that he has been
offended by an odor. Because of the widespread be-
lief that all sludges do have an odor, it is also gen-
erally a good idea to handle digested sludges in the
same manner. For that reason, the methods of sludge
application which provide the least visibility of the
sludge itself are recommended as the preferred prac-
tice.
The differences between sludges are sufficiently
marked to warrant tests of both chemical and physi-
cal properties before final design of the handling faci-
lities. The chemical characteristics are being dealt
with by others at this workshop, so I shall confine my
comments to the physical characteristics which affect
transportation and application costs.
Costs of Dewatering
Sludges to be handled have solids contents ranging
from 1 to 100 percent, the latter being heat dried
sludges. The costs of dewatering vary widely depend-
ing upon the particular sludge and technique being
used, but some generalizations will be made to illus-
trate basic concepts of how the desirable per cent
solids for a given situation can be analyzed.
The following fundamental assumptions will be
made regarding costs of dewatering:
Method
Lagoons, including excavation
Vacuum filter, including exc
Centrifuge
Filter press
Vacuum filter + heat drying
Lagoons, without excavation
Vacuum filter, without exc.
pertcnt
15%
25%
30%,
40%
99%
25%
25%
(ml/dry Ion
SI 5
22
20
30
JOO
5
16
161
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162
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
The actual costs for these processes vary consider-
ably with the particular situation which pertains to a
given case, and should be specifically determined for
that case. The figures given above are merely to be
used in this paper in the examples given to illustrate
the alternatives to be examined in designing transpor-
tation and application systems.
Hydraulic Characteristics
The hydraulic characteristics of sludges vary con-
siderably also with the percent solids. Figure 1 illus-
trates the variation of the apparent Darcy "f " as a
function of percent solids for a given temperature,
grease content, entrained air contents, etc., but for
the sake of simplicity, we shall in this paper use the
simple curves of Figure 1 as guidelines for the illus-
trative examples given. Sludge (A) is a hypothetical
example of a secondary sludge, and Sludge (B) is a
hypothetical example of a primary sludge.
It can be noted that below a concentration of about
eight percent solids the sludges behave as fluids with
an apparent "f "of .02 to 0.04. Sludges with 12 to 18
percent solids can be pumped, but with substantially
higher apparent friction factors, ranging up to, say,
t = 0.20 as a practical upper limit, except for extreme-
ly short distances.
These hydraulic characteristics would be measured
in the laboratory for any one sludge and the results
used in evaluating alternative systems.
here h^ = friction head in feet
L = pipe length in feet
D , pipe diameter in feet
V2/Z« = velocity head In feet
0.20
0.10
Alternative Transportation Systems
Pipeline
Pipeline costs are roughly proportional to the dis-
tance transported. Double the distance and you dou-
ble the cost. This is not true with some of the alterna-
tive forms of transportation, and therefore this im-
portant difference must be kept in mind.
Pipeline costs depend a great deal on the type and
permanence of the pipe used. In the work of Soil En-
richment Materials Corporation light-weight quick-
coupled pipelines have been laid over the surface of
the ground for contracts lasting one or two years.
Such lines are low in first cost, but the entire cost ot
the line must be written off over the duration of the
contract of which they are a part. For example, a
four-mile pipeline 12 inches in diameter was used for
one such project. The capital cost of the line and
pumps was approximately $200,000 installed. It was
used to move sludge for the warm months of the year
over a two-year period. The typical rate of flow was
1.5 MOD of five percent solids sludge, for a daily
movement of 300 dry tons. With 100 operating days
in each of two years, a total of 60,000 dry tons could
have been moved. (The actual contract quantity was
somewhat less than this amount so the full opportun-
ity to use the pipeline did not materialize.) The capi-
tal cost would have then been about $3.33 per dry
ton, or, say, 83c per dry ton mile. To this an operat-
ing cost would be added for, say, a rough estimating
total cost of one dollar per dry ton mile. For a
permanent pipeline written off over a period of about
20 years the capital, plus operating cost is estimated
to be approximately $11.30 per dry ton for a dis-
tance of 66 miles* . This works out to be about 17/
per dry ton mile. The figure did not vary greatly with
changes in percent solids over a range of four to
seven percent. Table I summarizes the analysis.
Truck Transportation
For purposes of this paper, the cost of the truck
transportation may be taken to be ten cents per wet
ton mile, including loading costs. The cost per dry
ton mile will then depend upon the percent solids
handled. Trucks can be designed to handle any per-
cent solids.
10 20
FEBCERT SOLIDS
igurc I Illustrative Diagram for Two Hypothetical Sludges
* Land Reclamation Project . Metropolitan Sanitary District of
Greater Chicago, 1967, Harza Engineering Co, Bauer Fngineermg,
Inc.
-------
ENGINEERING AND ECONOMIGS
TABLE 1
Calculation of Pipeline Transportation
Costs
Item
Pipeline length
Capital Cost (67)
Capital Cost (73)
Annual Capital
Cost. 6%. 20 yrs
Annual Operat-
ing Cost, energy
Annual Oncnil-
inp Cost, other
Total Annual
C'ost
Dry torWyear
4/dry ton
$/ dry ton
miles
Site I
65 miles
$20.7 million
414
373 "
OK "
0 52 ' '
4.33 ' '
365,000
$12.10
0.187
Site 2
57 miles
$18.5 million
37.0
3 33 ' '
OOK "
052 "
3 93 ' '
365,(XX>
SI 080
0 189
Site .<
66 miles
$19.7 million
39.4
3.53
008
0 52
4 1 3 "
365,000
$11.30
0.172
Sitf •>
35 miles
$12.7 million
254
2 29
06
52
287 "
365,000
$ 790
0225
(Based on Table G-l, 1967 "Land Reclamation Project" report by Harza Engineering Co. and Bauer Engineering, Inc to
Metropolitan Sanitary District of Greater Chicago.)
Barge Transportation
For purposes of this paper, the cost of barge
transportation will be taken as $1.50 per wet ton for
distances of 100 miles, and $2.00 per wet ton for dis-
tances of 200 miles, including loading costs. Again
the cost per dry ton depends upon the percent solids
which can be handled. The cost of unloading barges
is very much a function of the ingenuity of the design-
er, but because covered barges would in all probabil-
ity be required, it is conservative to assume that the
material would be handled in the slurry form, and
(with present practice) the percent solids would prob-
ably not be greater that eight percent, with six per-
cent being a more commonly attained figure.
Rail Transportation
Tank cars are the most commonly used carriers
for sludge at present. Unit trains of up to 40 cars at 85
tons each have been operated by Soil Enrichment
Materials Corporation, with 24-hour turn around
having been achieved as a steady practice for one-
way hauls of up to 170 miles. Under these conditions,
the cost of the rail transportation, including tank
cars is estimated to be, roughly, 1.2/ per wet ton mile,
including loading costs. For larger distances and
larger unit trains the cost would be more. (Note that
this figure does not include excavation of sludge from
lagoons, pumping from lagoons to tank cars, and ap-
plication to land.)
Again the cost per dry ton depends upon the per-
cent solids. Tank cars have been used successfully
with 12 percent solids sludge of a digested secondary
type. With primary sludges, 15 percent solids can be
handled successfully. The cars are equipped with agi-
tators to permit draining of these thick sludges from
the cars in a reasonable period of time.
Alternative Application Systems
The following alternative application systems have
been used for sludge applied to agricultural land:
1. Direct dumping of filter cake from truck, fol-
lowed by spreading and plowing into the soil.
2. Direct dumping of slurry from truck, followed
by plowing into the soil.
3. Flooding of prepared leveled ground from pipe-
lines, and later plowing of the dried sludge into
the soil.
4. Irrigation of slurry using high pressure nozzles.
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164
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
5. Plowing in of a slurry fed continuously through
a hose to a moving plow.
The latter system is the one presently preferred by
SEMCO, for the following reasons:
a) It is a one step method. There is no need to re-
turn to the site to plow the sludge in later.
b) It allows the material to be handled entirely in
closed containers. Lack of visibility to the general
public reduces aesthetic objections, even though
there may be no odor problems.
c) If there are any odor problems, even intermit-
tent ones, this method eliminates any adverse effects
on neighbors.
I have had considerable involvement with methods
4 and 5 preceding, and the preference for method 5 is
based upon that experience for rather large volumes
of sludge handled on a continuous long-term basis. I
have also had experience with smaller quantities of
sludge being applied with methods 1 and 2, and have
found these methods acceptable for smaller quanti-
ties, such as less than 50,000 wet tons of sludge at one
site for one season. For the sake of illustrating the
economic significance of the various combinations of
systems without getting into the benefits of particular
techniques of application, we shall use the cost figure
of $20 per dry ton for each of these application
methods; this includes the unloading costs from the
transportation system. It is beyond the scope of this
paper to discuss the advantages and disadvantages of
each of these methods, so that this uniform cost figure
will be used even though it is of course only a hypo-
thetical situation.
Excavation from Lagoons
The lagooning process, though it is an economical
method for the concentration of sludges, involves the
later step of reclaiming or excavating the sludge from
the lagoon. By contrast, a method for dewatering
which can be a part of a continuous flow sheet elimi-
nates the expense of this excavation. For purposes of
making cost comparisons here, the lagooning step
will be assumed to require the additional expense of
later excavation, and this will be taken to cost ten
dollars per dry ton, making a total of $15 per dry ton
for this method.
Comparison of Costs
Comparisons of the hypothetical costs of handling
sludge from a large city are given in Table 2. It must
be remembered that these hypothetical illustrations
are given simply for the purpose of furnishing exam-
ples which can be discussed here. Actual costs would
depend materially on the conditions peculiar to each
problem.
Alternative 1
This uses a lagooning at the site of the treatment
plant, followed by later trucking at 15 percent solids
to a site 20 miles distant, followed by dumping at this
site and later plowing into the ground. The transpor-
tation cost of ten cents per ton mile for a distance of
20 miles results in a cost of $2.00 per wet ton. Divid-
ing by 15 percent solids gives the $13.30 per dry ton
listed in the table for transportation.
Alternative 2
This is comparable to the operation of Alternative
1, except that rail haul for a distance of 100 miles is
used. The material is hauled at 15 percent solids, with
a freight cost of $1.20 per ton for the 100 miles.
Dividing by the percent solids gives the eight dollars
per dry ton figure listed.
Alternative 3
Vacuum filtration is used to develop a 25 percent
solids condition and then the material is hauled 20
miles by truck. The transportation cost of K)/ x 20
miles = $2.00 per wet ton is divided by 25 percent
solids to obtain the $8.00 per dry ton transportation
cost listed in the table.
Alternative 4
A portion of the sludge is concentrated by
vacuum filtration and then mixed with the unconcen-
trated balance of the sludge to produce a 15 percent
solids material. The cost is calculated for the filtra-
tion of 55 percent to be 0.55 x $16= $8.80 per dry
ton. This was rounded off to nine dollars, allowing a
small amount for mixing with the remaining 45 per-
cent of the material which would be at about three
percent solids. The resulting mixture is then 0.55 x
0.25 +0.45 x 0.03=0.1375 +0.0135 = 0.1510 or,
roughly, 15 percent solids. The transportation cost of
$1.20 per wet ton divided by the 15 percent solids
gives the eight dollars per dry ton transportation cost
listed.
Alternative 5
A 20-mile pipeline is used with the sludge as pro-
duced at the plant and thickened somewhat to, say,
five percent solids. This can be pumped easily with-
out high friction factors. The cost of the thickening to
five percent was ignored in the comparison, as it
would be small. The pipeline is written off over a
period of 20 years which results in \li per dry ton
mile cost, or $3.40 for the 20 miles.
-------
ENGINEERING AND ECONOMICS
Alternative 6
This is the same as Alternative 5, except that the
length of the pipeline is increased by 100 miles.
Alternative 7
A vacuum filtration of a portion of the sludge is
used as before, followed by mixing with the uncon-
165
centrated sludge to effect an eight percent dry solids
content which can be handled in a barge. The corre-
sponding cost of dewatering is of course low, but the
transportation cost of $1.50 per wet ton divided by
the three percent solids gives $18.75 per dry ton
transportation cost, which is seen to be relatively
high.
TABLE 2
Comparison of Alternative Methods for Handling
Secondary Sludge from a Large City
Di'striplion
1'i'r Dry 'Inn
Dt'watcrinn
Cost
Transportation
( 'o\i
Appluation
COM
1. l-agoomng and later
excavation, then
trucking to site 20
miles distant, where
it is dumped and
later plowed into the
soil at I59{ solids
2 Ixigoomng and later
excavation, then MX)
nules rail haul to site
at 159f solids, then
dilution and plowing
into soil at 109! solids
3 Vacuum filtration to
25rr solids, then truck
haul to site 20 miles
dist'iit where it is
dumped and latei plowed
into (he soil at 25%
solids
4 V acuum filtration ot 55%
to 25'! solids, then mix-
ing with remaining 459V
of sludge at V'. 100-miles
laii ii,importation at \5r'<
solids, then dilution ,md
plowing in at 10'•<• solids
5 Pipelining lor 20 \ears
at 5'V solids tor 20 miles,
the" latoomng, later
c\*.a\ation and plow
application at 10'? solids
<•> Same .is 5, except
tor HX! miles
7 I IK Vnilk- barging ot
*(>'' material after
\aaium filtration of
20'.' oi total and mix-
iiig v^ith remaining 809!,
followed by application
to land
$15
$13.30
$20 (X)
1X 30
15
8.00
20.CX)
43 (X)
16
8.00
2000
44 (X)
8.00
2000
37 (X)
15
15
3.50
3.40
17.00
18.75
20.00
20.00
2000
38.40
5200
42.25
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166
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Discussion of Alternatives
One of the main points of this paper is to point up
the great number of possible combinations of sludge
transportation and application schemes which can be
developed. This paper by no means exhausts the pos-
sibilities, but it does suggest the significance of con-
sidering the many possibilities which may be avail-
able.
First of all, the range of costs from $37 to $52 per
dry ton is seen to be relatively small. These costs are
also seen to be competitive with incineration. Unfor-
tunately, open competition between incineration and
transportation and land application as outlined in
this paper is usually not permitted. Much of the rea-
son for the lack of open competition is the present
policy of the federal government to share in the capi-
tal cost of systems, but not in the operating cost. The
transportation and land application systems are
usually low in capital cost, and relatively more ex-
pensive in operating cost than would be the incinera-
tors as long as the incinerators would not require re-
pair. Once the initial incinerators require substantial
repair and maintenance, and federal funds are not
available for this purpose, then the transportation
and land application is free to compete with the alter-
native of incineration.
Secondly, it is significant to note the wide range in
transportation costs when viewed separately. Note
that the most expensive is barge transportation, a fact
at odds with most commonly held opinions. The rea-
son is the assumption that barges would be used with
eight percent solids material, which is a solids con-
tent that permits the materials to be removed from
the barge as a fluid. The requirement that covered
barges be used for sludge transportation tends to
work against barging of material with a higher solids
content. In the case of the railroad tank car a much
higher solids content can be handled as the contents
can be agitated with air and the tank car pressurized
to force out the material as a thick slurry. It can then
be diluted, if desired, for subsequent land application.
Although all application costs were assumed to be
equal, this is of course not usually the case. For
example, it is unlikely that a barge unloading site
would be adjacent to the sludge application site. On
the other hand, the trucks can usually go very close
to the site of the application. Railroads are more like-
ly to be closer to the application site than barges, but
perhaps less close than would trucks. Mitigating
against the use of trucks is the farmer's opposition to
compaction of the soil by excessive truck traffic over
his tillable land. All of these factors would be taken
into account in any actual case.
SUMMARY
One purpose of this paper is to illustrate some of
the many possible combinations of sludge transporta-
tion and application which may be suitable to a given
problem.
Another purpose is to show the competitive nature
of the various alternative systems, and to demonstrate
that open and competitive bidding which would per-
mit a land application system to be considered as an
alternative to incineration could result in substantial
savings in cost, and also make use of the organic por-
tion of the sludge as a resource.
The benefits to the soil from the use of sludge for
enrichment have not been discussed, as these matters
are the subject of other papers of this workshop.
One final comment to provide a perspective: A cost
of $50 per dry ton of sludge for disposal corresponds
to less than two dollars per capita per year, as the
sludge from roughly 30 persons amounts to about one
dry ton per year. Possible differences in cost arising
from alternative systems are even smaller. It appears
that considerations other than cost should determine
the best use of this resource rich in organic material.
DISCUSSION
QUESTION: Ken Dotson, EPA, Ohio. How have
you determined that the toxicity from these high ap-
plications was caused by phosphate? It seems like
that at that rate of application there are a lot of
possibilities.
ANSWER: Well, I really didn't determine that. I
think we ought to ask Tom Hinesly. He was the guy
that suggested that idea. Tom did you hear that
question? Mr. Dotson asked me how I determined
that the decrease in yield with the high application
rates with soybeans was due to phosphorous, and I
told him I got that idea from you, so maybe you
could answer his question. We had these very high
loadings up to 180 dry tons per acre and got a drop in
the soybeans yield and Ithink you observed something
of the same sort in your higher application rates.
ANSWER: Tom Hinesly, Office of the Under-
secretary of the Army. Yes, on some of our ex-
perimental plots at Joliet we did have typical
phosphorous toxicity. The phosphorous contents
were about what they were in some studies that Dr.
Toby Kertz in our department had carried on, and so
we feel fairly competent that this was a phosphorous
toxicity.
QUESTION: John Walker. It seems that this is an
ideal opportunity for persons to get together in this
project and follow what is happening, because here
you have someone applying sludges up to 160 or
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ENGINEERING AND ECONOMICS
167
more dry tons per acre and you have such
questions—the statement was made earlier that you
have phosphate toxicity and then there was another
statement that you didn't have appreciable differen-
ces in uptake of metals you are probably using
Chicago sludge, is that right? Right. So, this is an op-
portunity it seems, to really follow this. I hope that
perhaps this is being done because experiences in
other places and other soils would suggest that you
might indeed get very high uptakes of metals. I would
hope to see that in this particular study that a person
would cover a sensitive crop and a non-sensitive crop
and look at the sludges and identify it well enough so
that a person does not draw the wrong conclusions
fiom the results of the experiment. They might come
up and say, well, you can apply this technique m
some other place.
ANSWER: Of course we recognize that some
crops are much more sensitive than others and we
don't plan to grow Swiss chard for example. Soybean
and corn are the normal crops. The phosphate
toxicity we expected to disappear with time through
the reversion process. In the meantime, we are going
to grow corn which is not affected, but I appreciate
your suggestion that some sensitive crops be grown. I
think we ought to do that and we do have some test
areas where this could be done, and I will take your
suggestion to heart and we will sec what we can
arrange. Maybe you could suggest some crops
-------
Recycling
Municipal
Sludges and
Effluents
On Land
T. C. WILLIAMS
Williams and Works
ABSTRACT
Briefly describes pretreatment considerations,
energy requirements and cost of operation of various
schemes involving land treatment designed by
\Villiams & Works. Lists twelve rather specific areas
where research would be most helpful to the design
engineer.
INTRODUCTION
This morning, Dr. Erickson mentioned one com-
munity in Michigan that had had some real problems
with land treatment of effluent. This was an expensive
error. It was not a Williams & Works project, fortu-
nately for us. We have, however, had some minor
problems. We prefer to call them "fascinating
failures" rather than "expensive errors." Michigan
has built more, and is building more, land treatment
schemes than any other state at the present time. We
are bound to have problems. We do not claim that we
have perfection. We're sort of like the chap at
church. The minister was giving a sermon on the rela-
tive state of imperfection of man, and he got a little
carried away and said, "I am not perfect, I'm sure no
one in the congregation thinks they are perfect. Any-
one in the congregation think you're perfect?" Lo
and behold, one chap stood up, and he said, "You
mean to say you think you're perfect?" The fellow
»aid, "No, I'm standing up for my wife's first hus-
band."
Our land treatment schemes have not reached that
state of perfection of the wife's first husband, we have
problems and we admit that we have problems.
Neither are the other methods of wastewater treat-
ment perfect. An example is an actinomyces infection
of the activated sludge plant at Ann Arbor. They
have a tremendous carry-over of solids on occa-
sion—they have problems. Everybody has problems.
It's just that when there's something different from
that which is being done commonly that we receive
notoriety for our "fascinating failures."
Maurie Ettinger, some years ago, wrote a wonder-
ful little paper entitled, "How to Plan an Incon-
sequential Research Project." He said, "the con-
sequences of successful research in many scientific
disciplines have been a series of great advances that
have taxed the economic, political, social and physi-
cal resources of society. In contrast, however, the
sanitary engineer has a distinguished record of earn-
est effort untarnished by embarrassing accomplish-
ments."
We want to have some freedom to make some new
mistakes. Let's not go on making the old ones. Let's
not make acceptable, used, mistakes. Let's make some
new ones. We will have an opportunity with the efflu-
ent disposal on to land to make new mistakes.
Williams & Works has had some experiences. We
have some facts. But the purpose here, as I under-
stand it, is to stir imagination, have ideas, get some in-
ter-disciplinary give and take, get more than the civil
engineer and the sanitary engineer's ideas on waste-
water treatment. We need, in addition to the civil en-
gineers and sanitary engineers, agronomists, agricul-
tural engineers, and we need farmers. You know,
really, we need farmers perhaps more than anything
else. They have a way of getting things accomplished
169
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170
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
that our public works people, by and large, don't
have. We also work with the SCS people when we're
planning a project. We work with the Extension
Agents in the area. These people have a tremendous
fund of knowledge that should be utilized.
One other thought, before I get to some real facts,
is that Barry Commoner in one of his books, "The
Closing Circle", develops four laws of ecology. The
fourth one is—"There's no such thing as a free
lunch." In any wastcwater treatment scheme, we must
be aware of this law. There's no such thing as a free
lunch. You pay for everything with something. It may
be with dollars, it may be with social cost, it may be
with environmental damage—whatever the costs may
be, there are costs. You just can't use dollar figures.
Pretreatment
The degree of pretreatment required will vary de-
pending upon the type of land treatment which you
are going to use. If you are going to use spray irriga-
tion, then you should have treatment equivalent to
the treatment that you would provide if you were go-
ing to dispose of this liquid into surface water. I be-
lieve very firmly that you should, before you squirt it
up in the air, give it at least as good a treatment as
you would give it if you were going to dump it in the
river. If you're going to do flood irrigation, then per-
haps treatment of a lesser degree is satisfactory. If
you're going to do grass filtration, then perhaps sim-
ple primary is adequate. But on all of these, you must
consider the question of public acceptance.
We have more and more concern over public ac-
ceptance. It's mandated in the law now. We have en-
vironmental hearings. We need to concern ourselves
with public acceptance. And in order to get public
acceptance at least at this stage of the world, I believe
that you have to be able to say the stuff that we're go-
ing to put on to the land for further treatment should
he at least as good as what we were going to put into
the river except, of course, for the removal of nutri-
ents.
There are many climatological constraints on the
pretreatment. We work in the northern part of the
United States, and in our part of the country we do
not irrigate in the winter time. We must store all of
the \vastewater that is generated during the winter
season. We must provide a minimum of five months
of storage. This is not as bad as it seems because as a
part of that storage you can also get treatment. So we
do provide storage for a minimum of five months and
the economics work out quite well. In the southern
part of the United States and in the water deficient
areas, perhaps you can irrigate during the winter
without excessive operating costs.
Land availability and isolation are also related to
the treatment that you provide. If you're going to be
out a thousand miles from nowhere, then you don't
have to be so concerned about the treatment that you
provide prior to the application to the land. I went to
Melbourne, Australia a few years ago. and I stood
out on their sewage farm at Melbourne and asked
them if they had any odor problems. Oh, on occasion
they did. There's a town down the road and they
complain about the odor. How far away is the town?
Oh, it's about twenty miles. This kind of an odor
problem we couldn't stand in our area. There may be
places where you can. It turns out, incidentally, that
the odor problems there were from the anaerobic la-
goon system, not from the land treatment system.
The processes utilized in treatment prior to irriga-
tion are:
l.No pretreatment other than maceration - lor
grass filtration.
2. Primary treatment.
3. Trickling filter.
4. Activated sludge.
5. Aerated lagoons.
6. Natural or facultative lagoons.
7. Anaerobic - aerobic pond systems.
In considering any and all treatment alternatives,
we ought to concern ourselves with the energy re-
quirements. Concern over energy is a very popular
subject at the moment. We use a lot of energy in
wastewater, and we ought to consider this.
The City of Wyoming in Michigan has a trickling
filter plant, and they have vacuum filtration of the
raw sludge with incineration of the filter cake. We
totalled up all of the energy input into the plant—(in-
cluding the last pumping station on the collection
system) this is the electrical energy, the gas and oil,
all of the purchased energy into that plant—and the
purchased energy required was 10,(XX) BTU per
pound of BOD removed.
Belding, Michigan has a facultative pond system
and uses about 1,200 BTU per pound of BOD re-
moved. In between that, an aerated lagoon with spray
irrigation used about 4,000 BTU per pound of BOD
removed. However, this last one (4,000 BTU) is a
land treatment scheme and there is 100 percent BOD
removal as opposed to the smaller percents in the
other facilities.
Methods of Land Application
I will just list some of the systems we have used
for spray irrigation:
1. Center pivot machines.
2. Winched pulled guns that travel back and forth
across the field.
-------
RECYCLING ON IANI)
3. Portable aluminum pipe systems.
4. Solid set systems.
We are now of a mind that we will probably not
design any more spray irrigation systems using any-
thing other than solid set systems. We find that for an
operating facility in the small communities that we
deal with, most of our clientele are towns of 10,000
and less, that in those communities we're better off
\\ith a solid set system that can be automated and
maintained relatively easily as opposed to other ways
of doing the job.
Flood irrigation is another method, and we have
paddocks that arc flattened out and dosed like the in-
termittent sand filters that we used to use. These are
irrigated in the summer only and will be cropped. We
have seepage ponds, or seepage beds, that can be
loaded year around. You're not dependent upon the
weather.
Grass filtration is another way. And then, of
course, there's subsurface disposal. You know, there
are half a million septic tanks installed each year in
the United States. Presumably, they all have tile fields
of some sort or another. This is sub-surface disposal,
and this is a tremendous number of units. A tremen-
dous number of dollars is spent on it, and we know
relatively little about the fate of goodies that come
out of these things.
Cost Effectiveness
Cost effectiveness as opposed to other treatment
methods. Just in case somebody comes along with a
wonderful little black box someday and we don't
iiave to have all of these pipes running around and
collecting the sewage, we can take care of it all at the
point of its origin. Just in case that somebody does
develop such a thing, we ought to look at the reclaim
value of the facilities used for wastewater treatment.
It we're using land as a part of the treatment project,
the land retains its value and, in fact, its value is en-
hanced.
We can grow crops. We do not believe that you
should anticipate a profit from crops in your plan-
ning of the financing for a project. We believe that
you should plan on the cropping being at best a
breakeven proposition.
There are, also, advantages in terms of green belt
development.
There are advantages in terms of recreational
areas. Working in deer country, we have found that
when you clean a piece of land off and use it for land
treatment, you provide an environment that is better
for deer than a forest. We have one pond and irriga-
tion scheme where we have a snowmobile trail
around the pond. They have races there. It's all or-
ganized and run by the Chamber of Commerce—a
very good utilization of that extra land that you have
to provide for isolation purposes. There are lots of
other recreational benefits.
We had an idea the other day that if we took the
wastewater before it went into the irrigation scheme
and put a little aerator in it and grew fish year
around, we could then build a cat food plant which
would give the little community an industry that they
don't have now. You can grow fish faster than you
can harvest them, and take the fish out and use them
to make cat food. This would be an interesting pro-
position.
Operation and Maintenance Costs
As I have said on other occasions, in all this pro-
gram for pollution control that we have at a national
level, our goal is not to build wastewater treatment
facilities but to control pollution. And, if we can't get
good operation of the facility, good maintenance of
the facility, we are not going to achieve the goal no
matter how fancy a facility we build. No matter how
we design it, we're not going to come out right il we
don't assure ourselves of good operation and main
tenance.
Let's talk about a two-tenths million gallons a day
plant - 0.2 MGD. This is a small town - 2,(XX) people
where 80 percent phosphorus removal is required. An
activated sludge plant costs $28 per capita to
run—just to run the thing. A trickling filter plant
costs $20 per capita; and an aerated pond with chemi-
cal precipitation of the effluent is $13 per capita An
aerated pond with irrigation of the effluent is $8 per
capita, and a facultative pond with irrigation of the
effluent is $6 per capita. Now to the people in that
small community, this is a per capita cost; so, you
must multiply it by three for the cost per household
There is quite a significant difference in the number
of dollars that they have to pay for operation and
maintenance of a wastewater treatment facility As
you increase the size of the facility, the costs get clos-
er together. At two million gallons a clay, the cost of
operation and maintenance is about $8 lor the acti-
vated sludge and $2 50 for the facultative pond and
irrigation system.
Research Needs
I have twelve things that occurred to me regarding
areas of research.
l.Air pollution. People are concerned about vi-
ruses and the bacteria flying through the air
when we spray irrigate. I just saw a study the
other day about air pollution around an acti-
vated sludge plant, and there's a problem that no
one has addressed themselves to very effectively.
-------
172
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
We ought to make some comparisons with the al-
ternatives.
2. Inflow and outflow quality comparison on ma-
ture pond systems. There are a lot of existing
• pond systems, and we ought to have better data
on the inflow and outflow characteristics. We
have one five cell pond system and one four cell
pond system. They have an anaerobic cell as the
first unit, and then facultative cells following.
In the one system, we have 350 days of storage at
the present flow, and in the winter we get about
2/ lOths of a part of phosphorus - 2/ lOths or
something like this of nitrogen out from under
the ice. That's an interesting thing. Maybe we
need to build our pond systems bigger and not
put the effluent on the land because we're mak-
ing such a high quality product that we don't
need to.
3. Another area that we ought to look at is the
quality of the ice that grows on a pond. As it
freezes, the ice on the top probably is pretty
good ice. Maybe if we could do some sam-
pling—I haven't done it yet—of this ice and then
if it's good stuff, harvest it and throw it in the
river, leaving the goodies behind. Maybe then
we'd only have half as much water to get rid of
come spring.
4. Muck and peat soils. There's some work being
done by the Forest Service and more needs to be
done on irrigation, using muck and peat soils.
5. Swamp irrigation. There is a project under way
for irrigating a relatively infertile swamp. It's be-
ing funded by the National Science Foundation.
We're going to study the eco-system in the
swamp and then put some treated effluent into it
and see if we can increase the number of duck-
lings per acre from the swamp.
6. Entomology. We have a problem with bugs
around the pond and irrigation areas - midges.
We're doing some work, with EPA money, at
Belding, Michigan on the entomology and the
problems of these midges.
7. Animals. We need more information on the
safety of feeding beef cattle and so on. In Michi-
gan, we have a running debate as to whether we
can feed cattle with the hay that we harvest off
an irrigation area.
8. We need some thermal studies. As this stuff
comes out of a pond, the pond is warm. The
water goes down to the ground and becomes a
part of the groundwater table, but it lays on top.
There isn't any thermal mixing. We need to
check and find out a little bit about this. Maybe
it scoots right along the top and comes into a
lake and then because of the temperature differ-
ential, there's an increase in the vegetation in the
lake because of the treated wastewater. There's
no problem with nutrients, but there is a prob-
lem with the increase in vegetation because of
temperature increase.
9. Movement of groundwater in the unsaturated
zone. Horizontal permeabilities are generally
greater than vertical permeabilities. Is the path
of water vertical in the unsaturated zone or is
there some spread? If so, how much? We need to
know to develop maximum phosphorus loading
computations.
10. Pond recirculation. We had some information
from Israel the other day that indicated that if
we had an anaerobic cell and if we took the ef-
fluent and ran it back through the anaerobic
cell, we would get much better nitrogen removal
because of this recirculation through the an-
aerobic cell.
11. Dissolved oxygen in the effluent. Does it make a
difference how much dissolved oxygen we have
in the effluent in relation to the need for the 5 ft.
aerated zone before you come to the water
table?
12. And then one that I added the other day. And I
wasn't being altogether facetious when I make
comment about the drinking water treatment,
that perhaps we ought to look at this whole thing
as a system—the water supply and the waste-
water treatment, because maybe you can give the
people a better quality of water to use as drink-
ing water, washing water and so on. As a result
of this, you have less of a problem at the other
end of the pipeline. So maybe those things ought
to be tied together someplace.
My closing thought . . . yesterday was experience,
tomorrow is hope and today is getting from one to the
other as fast as we can.
DISCUSSION
DISCUSSION: George Ward; Portland, Oregon. A
month or two ago you and I wrestled this matter of
septic tank effluent and I am glad you did bring it up
in that it is seldom discussed at these conferences. We
get carried away with the big plants and big
problems. We found that there are about somewhere
near eleven million spetic tanks in service, and for
every half-million that comes on, there are probably
less than a half-million taken off the line. We are not
even holding our own. Every time one goes out of
service, two pop up. That doesn't mean that the tank
is bad. In theory the discharge fields, I think are what
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RECYCLING ON LAND
173
you meant to chastise. But at your recommendation,
we did contact a Mr. Cecil Rose with the Farm and
Home Administration in Washington and I also met
someone from Sweden with some ideas on what they
are doing. And it is interesting to note, that I think
most of us assumed that if you have a septic tank, you
use the conventional procedure. It is not necessarily
true, in that you can use the septic tank not only as a
solids interceptor and by the addition of one or two
more just quieting tanks, relatively small, and also the
draw of tubes from one tank to the next. You are go-
ing to prevent solids carry over, and then you are
dealing with just anaerobic effluent reasonably free
of solids. Then you don't have to quit. It is an easy
matter to take some rather inexpensive plastic type,
what FHA calls a variable gradient pipeline, just a
PVC tube bearing. You can then pump it some
distance away from your source, put it into aerated
lagoons or do whatever you want to it. So, my point,
was that I don't think it was your intent to chastise
the septic tank. I think in your closing remarks where
you suggested imagination, we should probably apply
some there and what to do with the enemies that
come out of those third tanks.
CHAIRMAN: Do you want to respond to that
Ted?
ANSWER: Ted Williams, Michigan. I suppose 1
should. I am not real sure what I should say. There
are many places where septic tank and tile field
systems properly designed and properly maintained
are a viable alternative to public sewerage systems.
Many times we are in the situation where we go
around and say, "Oh, look at all those septic tanks"
and the terrible problem or the potential for a
terrible problem and we have to get rid of them. We
can't allow this property to develop on septic tanks
and tile fields. So we select it all together and then we
remove 80 percent of the goodies and dump it in a
creek. Well, you might better have left it in the land
in the original case, if the soils are right and if the
design is proper. But, like all of these systems that we
are talking about, all of the alternatives that we con
sider, it is a matter of design: proper, good design -tud
good management. These are the important con-
siderations and in some places one is best and in some
places another is best.
CHAIRMAN: I might add one point to that. Un-
der the new Public Lw 92-500, The Federal Water
Quality Act Amendments of 1972, EPA is charged
with developing or reviewing the whole septic tank
problem. We call it rural waste. And so if any of you
have any ideas, good ones, we would be interested in
hearing from you.
-------
Economic Aspects
of the Application
of Municipal
Wastes to
Agricultural Land
W. D. SEITZ
and
E. R. SWANSON
University of Illinois
ABSTRACT
The implications of minimizing the cost of waste
treatment and of its disposal on agricultural land are
presented. In the process of cost-minimization account
is taken of crop returns from application of waste and
of environmental damage. The optimal rate of appli-
cation of waste to crops is shown, in principle, to be
influenced by all variables and functions in the sys-
tem, including the marginal cost of alternative
methods of treatment and disposal. Research needs in
the general terms of the cost-minimization model are
discussed.
A simulation analysis of a particular land-reclama-
tion sludge-disposal project is described. The variables
found to be most influential in performance of the sys-
tem included: transport costs for sludge, site prepara-
tion costs, assumptions regarding the nitrogen budget,
choice of cropping system, and source of labor used in
site preparation. It follows that research on these vari-
ables would improve decision making regarding the
application of waste to crop land.
INTRODUCTION
Our assignment of considering "systems ranging
from maximized productive crop utilization to maxi-
mum capacity accommodation . . ." requires that we
review the economic logic of a total system of waste
disposal on agricultural land. This will permit us to
pinpoint more clearly the kinds of information
needed for analysis of the desired balance between
the multiple objectives of economic crop production,
minimum-cost waste disposal, and environmental
quality objectives.
In what follows we present first a simple cost-mini-
mization model which will indicate the principal re-
lationships within the system as we view it and thus
provide a framework for indicating the relative infor-
mation needs in general terms. This will be followed
by a discussion of a simulation model of a land-rec-
lamation sludge-disposal project. Sensitivity analysis
will indicate the relative importance of additional in-
formation on specific variables.
Cost-Minimization Model
We use the following notation:
Wj= quantity of waste to be applied to land in
crops.
W2:= quantity of waste for disposal by an alter-
native method.
W = total quantity of waste for disposal.
(W, iW2 = W)
TC, = cost of treating, transporting, and apply-
ing waste, W, , to crop land
TC2=cost of treating and disposing of waste,
W2, by an alternative method.
A = acres of crop land used for waste disposal.
X = quantity of resources (other than W, and
A) used in crop production.
Y = physical quantity of crop produced.
Ca= cost per acre to gain control of land (may
be rent, annual cost of purchase, annual cost
of purchase and reclamation, etc.).
Cx= cost per unit of non-land and non-waste
resources used in crop production.
P = selling price per unit of crop.
D,= dollars of damage (considered as a cost to
175
-------
176
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
the system) to environment caused by use of
W, on crop land.
D2= dollars of damage (considered as a cost to the
system) to environment caused by discharge
of W2 (alternative to the disposal-on-land
method of treatment and disposal).
These variables are related to each other by the
following set of functions:
Y = Y(W,, A, X) Crop yield response function. (1)
TCi =TCi(W,) Cost of treating and disposing
of Wi on crop land. (2)
TC2 = TC2(W2) Cost of treating and disposing
of W2. (3)
DI - D!(W,) Environmental damage func-
tion for W,. (4)
D2 = D2(W2) Environmental damage func-
tion for W2. (5)
Of the many institutional arrangements, we con-
sider the one in which the two waste disposal proc-
esses and the agricultural crop operations are viewed
as if they were within a single decision unit. We note
that another speaker has the assignment of discussing
institutional options. This decision unit wishes to
minimize the total cost, including damage to the en-
vironment and any offsetting return from crops, of
disposing of a given amount of waste, W. The deci-
sion unit may purchase land directly or rent land by
the acre on a cash basis rather than crop-share. Prep-
aration of the land for crop production (e.g., levelling
strip-mined land) may also be included in the cost.
Further, the damage to the environment by use of
both (1) the land-disposal process, and (2) the alter-
native process must be borne by the decision unit.
That is, we assume that what are usually viewed as
externalities have been internalized.
The objective of the decision unit is to minimize
total cost, TC, which is defined as follows:
TC = TC,(W,) + D,(W,) + TC2(W2) + D2(W2)
- PyY(W, , A, X) + CaA + CXX
(6)
subject to W= W! + W2 or the disposal of all waste
generated by the decision unit. Minimization of TC
results in the following conditions:
9TCi ^ 3Di p. dY
__! -|- _ py
~1\\7 -ilI7 J I n.«>
aw,
aw,
(8)
(9)
These three relations, 7, 8, and 9, together with W =
W, + W-, provide a solution for the four unknowns,
W, , W,", A, and X.
Our assignment indicated that we should focus on
the rate of waste application per acre, W, / A. It can
be seen that the optimal rate depends, in principle, on
all other variables and the relationships among them
in the system. The degree of dependence is, of course,
an empirical question. To indicate how the rate
W, / A fits into the system, we refer first to Figure I.
Amount of Waste Applied to Land
Figure I: Gross Return and Marginal Return from Application of
Waste In Crop Production.
With the price of the crop, Py, fixed, this curve has
the same shape as the crop yield response curve. The
marginal return, NL, indicates the addition to gross
return if the waste, W, , were costless. Note that if we
were to view profitable crop production as the sole
objective in such a situation, OL is the optimal
amount of waste to apply. If W, is not costless, how
should it be priced? To answer this, we need to go
back to equation (7), one of the conditions for total
cost minimization for the entire system. This condi-
tion indicates that the total marginal cost for the land
disposal method (including environmental damage
and return from crops) must be equal to the total
marginal cost of disposal by the alternative method.
In Figure 2, the left-hand side of equation (7) is
graphed. For simplicity, we assume that the functions
Tor yield response (1), total cost, TC, , (2), and dam-
age (4), are quadratic in W, , thus giving linear deri-
vatives. Line MK.P represents the total marginal cost
of waste disposal on crop land. As in Figure 1, OL
represents the amount of waste, W, , to be applied for
maximum crop yield per acre. Suppose that the total
marginal cost (treatment and disposal cost plus en-
vironmental damage) for the alternative method
-------
ECONOMIC ASPECTS
177
Amount of Waste Applied to Land
Figure 2 Total Marginal Cost of Waste Treatment and Disposal on
Land
(right-hand side of equation (7) ) is OS (or RP). This
would require an application rate OR in excess of
maximum crop yield per acre. If the total marginal
cost of the alternative method were to decrease suffi-
ciently, the optimal application rate would drop to
less than OL. Optimal application rates less than OK
would mean that disposal on land created, in total, an
income rather than a cost.
Of course, other variables besides the marginal
cost of alternative disposal methods could affect the
optimal application rate. For example, the price of
the crop, Py, the rent or cost of land, C.,, etc. The
marginal value product of waste (NL) also has im-
plications for the price a farmer can afford to pay for
varying amounts of waste, W|. If crop production is
viewed as a separate decision-making unit, amounts
of waste less than OL, have a positive value and could
command a price; applications in excess of OL would
cause financial loss to the crop enterprise and would
require compensation.
General Research Needs
In this section we present an assessment of broad
categories of research needs. After presentation of the
simulation model, the specific needs as revealed by
that analysis are presented. In the cost-minimization
system, the optimal rate of application of waste to
cropland, W, /A, depends on knowledge of the func-
tional relationships (1) through (5) and prices and
costs. How much do we know about each of these
relationships'.7
Yield Response Relations. Although in the Corn
Belt a number of experiments have been conducted to
estimate crop yield response to the plant nutrients " ,
very few have made estimates of the yield response to
water16. Fewer still have made estimates of the unm
effects on crop yield of adding nutrients and water4 IS.
These joint effects effects are of particular impor-
tance in the application of wastewater and sludge.
Further, few experiments have examined the yields
past the maximum. There has previously been no eco-
nomic need for interest in this zone. In summary, our
estimates of the crop production relation (1) present-
ly depend largely on informally synthesized judg-
ments of individuals familiar with crop yield under
different nutrient-moisture regimes.
Cost Functions. Relationships (2) and (3) involve
basically engineering estimates and it would be ex-
pected that the parameters in these equations could
be estimated with relatively greater precision than (I)
which is an essentially biological relationship. If (3)
refers to a conventional system of treatment and dis-
posal, one would expect that experience on the
technical relationships together with the updating of
costs, would give us rather precise knowledge of this
relationship.
Damage Functions. Perhaps our knowledge is
most meager in the case of the damage functions, (4)
and (5). Although these damages are expressed in
dollars, in the case of many of the potentially harmful
aspects of applications of wastewater or sludge, we do
not even know the fundamental physical relation-
ships. For example, the transformation in space and
time of plant nutrients and heavy metals represent
processes that are not well understood. As a result,
public policy attempts to reduce the adverse environ-
mental impact by such methods as setting standards.
Case Study: A Simulation Analysis
Background. A recently completed economic
simulation study provides some indication of the type
of analysis needed and begins to identify important
variables and relationships requiring further study".
The case being studied involves the disposal of mu-
nicipal sludge on reclaimed strip-mined land on a
large scale basis.
The Metropolitan Sanitary District of Greater
Chicago (MSD) is charged with the treatment and
disposal of the sewage waste of the city, its suburbs,
and its industry. One of the products of this activity is
over 900 dry tons of anaerobically digested sludge
per day. In the past it was lagooncd, dried, or inciner-
ated, all of which are now impractical As a result,
the MSD searched for other means of disposal, in-
cluding both carrying out experimental projects and
supporting organized research efforts'2 " N.
-------
178
RECYCLING MUNICIPAL SLUDGKS AND KFFLUKNTS
Fulton County, Illinois, located 170 miles south-
west of Chicago, has had over 50 thousand acres of its
land area disturbed by strip mining operations, and
mining continues at the rate of about 2,000 acres per
year. There is considerable public pressure within the
county to utilize the disturbed acreage in some useful
manner, if possible to return it to row-crop produc-
tion, its use prior to mining. The soils being stripped
are generally of high quality. The overburden in the
county is calcareous so that acid wastes are not a
problem, and the establishment of a cover crop is not
particularly difficult. Also, the material is free
enough from large rocks to allow the operation of
agricultural machinery if the slopes are sufficiently
gentle.
After preliminary explorations by officials of Ful-
ton County concerning the alternative of utilizing
sludge in reclamation of spoil land and after some
contact with the MSD, the MSD purchased a tract of
approximately 7,000 acres. Additional land has been
purchased subsequently. The general thrust of the
project is that sludge will be applied on land that has
been leveled and that row crops will be produced on
the land. Thus it roughly conforms to the single deci-
sion-making unit described under Cost-Minimization
Model.
Research by agronomists has indicated that pollu-
tion problems would not be a constraint in this type
of operation7 *. Heavy metals are apparently not ab-
sorbed in the plants to levels that can be considered a
problem. The constraint on the quantity of sludge ap-
plications is expected to be the nitrogen which it con-
tains in both organic and inorganic form. A system of
capturing all surface water and monitoring ground-
water has been established to minimize the possibility
of pollution episodes.
The Project and The Simulation Model
The disposal-reclamation project involves the
i-hipment of sludge to Fulton County on the Illinois
river by barge and piping it to one of three lagoons
with a total storage capacity of over eight million
cubic yards. The possibility of constructing a pipeline
from Chicago to Fulton County is being considered.
The stripped land is leveled so that cropping opera-
tions are possible and surrounded with berms so that
all runoff can be recycled in the event of water qual-
ity problems. The sludge is pumped out of the la-
goons and sprayed on the prepared sites before plant-
ing and during the growing season, weather permit-
ting. The crops grown will probably be typical cen-
tral Illinois row crops, but the zero tillage practice
will likely be used to reduce runoff and minimize the
need to collect rocks.
The quantity of sludge applied over the life of the
project will depend on (a) the initial level of organic
nitrogen in the soil; expected to be very low relative
to normal soils, (b) the nitrogen removal from the soil
in the form of harvested crops, and (c) the excess of
nitrogen application over nitrogen removal possible
while avoiding leaching problems.
In order to appraise the importance of the several
variables influencing the operation of the project, a
deterministic simulation, or multi-period cost and
benefit accounting model, was constructed and ap-
plied with the support of the Illinois Water Resources
Center. A diagram of the model is in Figure 3. The
model is less sophisticated than most simulation
models in that in many cases it was constructed on
point estimates of the relationship between variables,
rather than functions. This was necessary when the
only estimates available were the initial estimates
available from the MSD. As experience is gained, in
this project or in others, it will be possible to substan-
tially improve the model. At this point, however, it is
possible to begin to identify the variables that are im-
portant determinants of costs and benefits to the
MSD and to the county. In contrast to the cost-mini-
mization model, indirect benefits from any increased
income are also considered.
Figure 3' Flow Chart for Simulation Analysis.
The model reflects the operation of the project
from transportation of the sludge from Chicago to the
site, storage, handling, and application on the land. It
reflects costs of leveling the land prior to application
and farming which will vary over sites as well as a
constant per acre cost for runoff control. The pro-
ductivity of the soil is determined by sludge applied
and crop residues, which in turn determines the nitro-
gen present in the soil. The nitrogen requirement of
-------
ECONOMIC ASPECTS
179
the crops grown is compared with nitrogen present to
determine annual sludge applications possible, if any.
Crops produced and land values determine crop
expenses, yields determine gross crop revenues and
the difference is net crop revenue to the MSD. The
increases in land values due to changes in quality and
the savings over other methods of sludge disposal are
added to crop revenue to determine gross MSD bene-
fits1 !. The costs of transportation, storage, applica-
tion, leveling, land purchases and monitoring are
subtracted to determine net district benefits. Crop ex-
penses and costs of operations carried out in the
county determine initial county benefits, which are
assumed to have a multiplier effect on county in-
come. All costs and benefits are calculated by year
over a ten to twenty year horizon and are discounted.
Results Generated
In line with the objectives of the analysis those
variables that have a significant impact on the perfor-
mance will be identified, roughly in order of their im-
portance.
I nuisportation Costs. At present, the sludge is be-
ing shipped 170 miles to Fulton County by barge un-
der a contract with an independent firm. If the results
under this contract are compared with the results as-
suming construction of a pipeline prior to project ini-
tiation, a substantial difference of more than $2000
per acre over a ten-year period and over $3000 per
acre over a twenty-year period are observed. While it
is possible that future bids for barge transportation
may be lower and the actual cost of the shipment via
pipeline may be higher than estimated, the clear ad-
vantage of a pipeline is evident''.
Site Preparation Costs. The costs of clearing and
leveling spoil bank land as a part of any reclamation
project is a subject of considerable disagreement.
This project differs only in that an additional opera-
tion of constructing berms or other devices for con-
trolling water runoff is necessary. The MSD estimates
this to be a constant $300 per acre regardless of the
nature of the specific site. This is added to the cost of
clearing the site of brush or trees, if any are present,
and of leveling. Depending on the roughness of the
site, leveling and clearing is estimated to range from
several hundred to several thousand dollars per acre.
In the standard runs in this analysis this was assumed
to be $400 (plus the $300 constant). Most of the cost
estimated for leveling operations are based on experi-
mental, one-time, projects carried out on sites of
widely differing types. Over a period of years long
enough to allow contractors to gain experience on
the conditions found in Fulton County, the costs per
acre may be reduced. That is, a learning curve may
exist'. A trade-off also exists between the leveling <>l
progressively rougher land on sites already owned
and the purchase of additional sites that include less
rough spoils but are more distant from the storage la-
goons. This aspect was not included in the model.
In this model the costs of site preparation are in-
cluded as first year costs to the MSD. These costs are
included in county benefits, in total or in part, de-
pending on whether local contractors and local
laborers are utilized. The specification of local
operators for such activities has a significant impact
on the level of income generated in the county, as
will be noted.
The Nitrogen Hudxet The third most important
factor is the quantity of nitrogen applied. II the only
project objective was sludge disposal, the most eff'
cient technique would likely be very heavy apphca
tions on a small acreage, essentially the cscation of
lagoons or at least areas that would havr levels of
water and nitrogen too high for crop production
Given the second objective, that of crop production,
the sludge disposal objective could be most effective-
ly met by operating in the third stage of the produc-
tion function, that is, in excess of OL in Figure 1, in
terms of water or nitrogen applied. Presumably the
nitrogen limit would be reached first and operation in
the third phase would imply potential nitrogen pollu
tion problems, although the relationship between ni-
trogen applications on farm land and nitrogen pollu-
tion in surface water is a subject of continuing con-
troversy ;:".
Since research is not available demonstrating the
relationships among nitrogen application, crop pro-
duction, and pollution on strip-mine spoils, it was
necessary to utilize the experience on normal soils
which can be broken into its stock and flow aspects as
suggested in Figures 4A and 4B. Normal fertile soils
carry a stock of organic nitrogen, a portion of which
becomes available to crops in each year through min-
eralization to an inorganic form which is also subject
to leaching problems, Figure 4A. Strip-mine spoils
have much less organic nitrogen present, in some
cases it may be essentially void, point 0 on the right-
hand side of Figure 4B. Over half ol the nitrogen
present in sludge is in organic form and therefore
sludge applications will gradually build up the level
of organic nitrogen in the soil, as will crop residues
The flow aspects involve the application of inor-
ganic nitrogen, the loss of nitrogen through volatil-
ization, removal in the form of crops, and possible
losses in the form of runoff or leaching into the
groundwater. It has been estimated that on normal
Illinois soils approximately I/ 3 more commercial in-
organic nitrogen is added than is removed by crops
produced2 2.
-------
180
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
cr>
o
200
Crop Nitrogen
Requirement
Nitrogen Provided by
Soil Organic Matter
Time
(o) Undisturbed Farm Land
/'/Inorganic Sludge'
//Nitrogen Added/
Crop Nitrogen
Requirement
Nitrogen Provided by
Soil Organic Matter
Time
(b) Strip-Mined Land Being Reclaimed With Sludge
Figure 4 Nitrogen Supplied to Crops by Fertilizer and Organic
Matter
The potential impact of the two variables, the ini-
tial level of organic nitrogen present and the relation-
ship between the nitrogen applied and that removed
is quite significant, as indicated in Figure 5. In this
figure ONP, is the original stock of nitrogen in the
first year. The ratio of N applied to N removed is de-
noted as G. If the original stock is assumed to equal
levels present in normal fertile soil (ONP, = 0) and
the maximum allowable application of nitrogen is
equal to that removed by the crops (G= 1.0), only 53
dr\ tons of sludge can be applied over a ten-
year period. If the original stock value is zero
(ONP, = 5333 Ibs.) and twice as much nitrogen can
be applied as is removed by the soil (G = 2.0), 195
tons can be applied over ten years. Over the ranges
considered, the original stock of nitrogen present is
slightly more important than the relationship between
annual applications and removals.
Cropping Systems. A variety of crop rotations,
continuous single cropping and continuous double
cropping options were analyzed. Generally systems
using large amounts of sludge nitrogen are the most
desirable, as is suggested in Table 1. The economic
benefits from using heavier levels of sludge outweigh
any differences in net revenue from cropping opera-
180
160
140
120
IOO
ao
60
40
20
G - Crop Nitrogen
Applied N
Multiplier = ——
Removed N
ONP| Is the Amount of Organic
N In Soil In Year I
I
0 -1000 -2000 -3000 -4000 -5000 -6000
ONP| (pounds per acre )
Figure 5: Effect of G and ONP, on Amount of Sludge Applied Over
Ten Years.
tions. For this reason the double cropping operations
are superior to single cropping. Both of these are
superior to crop rotations.
One problem with crop rotations is that the inclu-
sion of crops with low nitrogen requirements lower
the MSD benefits, as noted. But also, nitrogen pollu-
tion problems are an apparent threat with rotations.
This is due to the build up of soil organic nitrogen
levels through applications in the years when crops
demanding high levels of inorganic nitrogen are
grown. Then when crops with low nitrogen demands
are grown, more nitrogen is converted from an or-
ganic to an inorganic form than is utilized by the
crop. The excess may leach into the groundwater.
The cropping systems which the model suggests
will perform best are: corn-rye double cropping, for
grain or silage; sorghum-sudangrass; and corn single
cropped. For example, almost 50 percent more sludge
is applied over ten years with the corn-silage-rye sys-
tem than with a corn-soybeans-wheat-alfalfa rota-
tion.
Labor Use. The use of local labor and local con-
tractors to perform the physical activities of the proj-
ect is an important determinant of county income.
Without an income multiplier (that is, a multiplier of
-------
ECONOMIC ASPECTS
181
TABLE 1
Sludge Applied and Break-Even
Alternative Disposal Costs for Ten
Years of Selected Cropping Systems*
Variations in the discount rate from four to rweh e
percent did not significantly influence project per-
formance due to the high cost load in the first year of
the project.
Cumulative
Sludge Applied
(dry tons/acre)
Double Cropping
No- Tillage
Corn (silage) 149.8
with Rye
Corn (grain) 148.2
with rye
Continuous Crops
Sorghum-Sudangrass 156.7
Corn (silage) 119.9
Corn (gain) 118.2
Alfalfa 112.0
Crop Rotations
Corn-Corn-Corn- 125.4
Sorghum-Sudangrass
Corn-Corn-Corn- 118.6
Corn silage
Corn-Soybeans 111.7
Corn-Sorghum-Sudan 111.6
Wheat-Alfalfa
Corn-Soybeans- 99.0
Wheat-Alfalfa
^Assumptions.
ONPi = 3333 Ibs. G = 1.3
Discount Rate = 8%
Leveling Cost = $400/ acre
Barge transportation
one), the present value of income generated in the
county over ten years is $113 per acre when outside
contractors and labor are utilized. If local labor is
used by outside contractors this jumps to almost
$500. If both local contractors and local labor are
used, this increases to $626.
The existence of a multiplier will further increase
these benefits. A multiplier of 1.11, as was estimated
for Fulton County'', would increase this to $695. If it
equalled 2.0, the benefits would double from $626 to
$1252.
Other Variables. The remaining aspects of the
project are, at least in relative terms, not highly sig-
nificant determinants, of project performance. The
costs of the storage lagoons, pumping and application
systems, etc., are large but the impact of changes of
these costs over reasonable ranges is not significant.
Break-Even
Alternative
Disposal Cost
(dollars/acre)
67.15
6789
68.23
74.82
76.03
78.50
74.47
75.56
77.85
79.06
83.87
SELECTED RESULTS AND
CONCLUSIONS REGARDING
RESEARCH NEEDS
Since the estimates on which this analysis is based
are approximate, the results are less than exact. Some
of the results will be presented, however, in order to
provide a general understanding of the project.
Based on assumptions that appear reasonable for
the level of nitrogen present and crop utilization, the
following can be reported. Almost 150 dry tons per
acre of sludge could be applied in the first t'-n years,
with another 100 + tons being applied in the following
ten years. The net present value of the cost of the
project to the district would be about $68 per dry ton
using current transportation methods and about $39
per ton if a pipeline were constructed. The project
would generate economic activity in the county
amounting to $600 to $1200 per acre depending on
the multiplier and assuming that local labor and con-
tractors are used.
It seems that it is reasonable to conclude that a
project of this nature is economically feasible. The
MSD will be able to dispose of significant quantities
of sludge, and if the pipeline is constructed, be able to
do so at a lower cost than with previous methods. The
county will realize benefits in that significant acre-
ages of strip-mined land will be reclaimed and signif-
icant levels of income will be generated. It is this
anticipated benefit by both parties that resulted in the
initiation of the project".
Of course, additional research needs to be done.
While the information on which this simulation is
constructed is quite crude, the results do suggest
areas for further work. The variables identified as im-
portant determinants of project performance are the
logical candidates for early effort. More information
is needed on the nitrogen balance aspects of crop
production with sludge and water application. The
full range of the production function needs to be de-
termined, along with estimates of possible nitrogen
losses to the environment. This information is needed
on a variety of crops. While the presumption of no
heavy metals pollution is accepted in this analysis,
additional work will likely be necessary in this area.
Improved estimates of the costs of site preparation
are needed. Perhaps this large-scale project will
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182
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
generate a reasonable set of data on the costs of level-
ing stripped land under a range of different spoil con-
ditions. Perhaps more efficient techniques of accom-
plishing the task can also be developed. The wide
range of cost data available from small demonstra-
tion projects are of minimal usefulness in a project of
this type.
In addition to the variables identified here, there
are the socio-political aspects of the project that are
crucial to its continued operation. Some past experi-
ence suggests that these considerations may be more
important than the economic-engineering aspects.
While the possibility of problems which would stop
this operation exists, it appears that it should be suc-
cessful. It may well demonstrate that a profitable in-
teraction between agriculture and urban centers is a
realistic goal.
ACKNOWLEDGEMENT
This research was supported in part by funds pro-
vided by the Department of Interior under the Water
Resources Act of 1964, PL88-379, OWRR Project
No. S-025-I11.
BIBLIOGRAPHY
1. Aldrich, S. R. "Plant Nutrients In Crops, Crop
Residues and Miscellaneous Materials." Agronomy
Facts, Vol. 7, SF-61, College of Agriculture, Univer-
sity of Illinois, Urbana, Illinois. Feb. 1960.
2. Aldrich, S. R. "Some Effects of Crop-Produc-
tion Technology on Environmental Quality." Bio Sci-
ence 22(2):90-95. 1972.
3 Brickner, W. H. Pricing Strategies for New In-
dustrial Products In Oligopolistic Systems. Palo Alto,
California. By the author, 45 Newell Road. 1966.
4. Fulcher, Charles E. "Yield Response Curves of
Corn Affected by Variables of Nitrogen, Plant Popu-
lation, and Moisture Supply." Unpublished Ph.D.
Thesis. University of Illinois, Urbana. 1961.
5, Christensen, T. and A. Matson. Impact of Irriga-
tion Development On Income and Trade. Bulletin
550, Economics Department, Agricultural Experi-
ment Station, South Dakota State University, Brook-
ings. South Dakota. 1969.
6. Dalton, F. E., G. E. Stein, and B. T. Lynam.
"Land Reclamation—A Complete Solution to the
Sludge and Solids Disposal Problem." Journal of
Water Pollution Control, May 1968, Part I.
7. Hinesly, T. D. and B. Sosewitz. "Complementary
Relationships Between the Reclamation of Surface-
Mined Land and Sludge Disposal." Paper presented
at the 1971 Coal Convention, Pittsburgh, Pennsyl-
vania, May 1971.
8. Hinesly, T. D. and B. Sosewitz. "Digested Sludge
Disposal on Cropland." Paper presented at the Water
Pollution Control Federation's 41st Annual Confer-
ence. Chicago, Illinois, September 1968.
9. Hogan, Joseph W. "The Use of Digested Sludge
to Reclaim Strip-Mined Land: An Economic
Analysis Using Computer Simulation." Unpublished
M.S. Thesis. University of Illinois, Urbana-
Champaign. 1973.
10. Kneese, Allen V. and Blair T. Bower. Manag-
ing Water Quality: Economics, Technology, Institu-
tions. John Hopkins Press, Baltimore. 1968.
11. Leonard, Daniel. "Some Economic Aspects of
Reclaiming Strip-Mined Land with Digested Sludge."
Unpublished M.S. Thesis. University of Illinois, Ur-
bana-Champaign. 1972.
12. Metropolitan Sanitary District of Circatcr
Chicago. Land Reclamation: The Natural Cycle I(X)
E. Erie St., Chicago, Illinois. October 1972
13. Metropolitan Sanitary District of Circatcr
Chicago. The Beneficial Utilization of Liquid fertil-
izer on Land. Undated Publication. 100 E. Erie St.,
Chicago, Illinois.
14. Metropolitan Sanitary District of Greater
Chicago. The Prairie Plan. 100 E. Erie St., Chicago,
Illinois. April 1971.
15. Seitz, W. D. Implications of Strip-Mining of
Coal from a Tax Perspective: A Preliminary Analysis
Based on Selected Illinois Counties. State of Illinois,
Department of Local Government Affairs, July 1971.
16. Swanson, E. F. and E. H. Tyner. "Influence of
Moisture Regime on Optimum Nitrogen Level and
Plant Population: A Game Theoretic Analysis."
Agron. Journal 57(4):361-364. 1965.
17. Swanson, E. R. "Economic Analysis of Water
Use In Illinois Agriculture." Research Report No. 38.
University of Illinois, Water Resources Center. Janu-
ary 1971.
18. Swanson, E. R. and W. D. Seitz. "The Role of
Local Institutions In a Land-Reclamation Sludge Dis-
posal Project." Paper presented at 1971 meeting of
American Agricultural Economics Association. Ab-
stract appears in American Journal of Agricultural
Economics 53(5):860-861. December 1971.
19. Swanson, E. R., C. R. Taylor, and L. F. Welch.
"Economically Optimal Levels of Nitrogen Fertilizer
for Corn: An Analysis Based on Experimental Data,
1966-1971." ///. Agr. Earn. Vol. 13, No. 2. July 1973.
20. Taylor, C. R. "An Analysis of Nitrate Concen-
tration In Illinois Streams." ///. Agr. hcon. 13(1): 12-
19. January 1973.
21. Welch, L. F., D. L. Mulvaney, M. G. Olkham,
L. V. Boone, and J. W. Pendleton. "Corn Yields with
Fall, Spring, and Sidedress Nitrogen." Agron. Journal.
63:119-123. January-February 1971.
22. Welch, L. F. "More Nutrients Are Added to
Soil Than Are Hauled Away In Crops." University of
Illinois Agricultural Experiment Station, Urbana,
Illinois. Illinois Research, Vol. 14, No. 1, Winter
1972.
-------
Monitoring Considerations
for Municipal
Wastewater Effluent
and Sludge Application
to the Land
PAUL A. BLAKESLEE
Michigan Department of Natural Resources
ABSTRACT
Monitoring the performance of the many interre-
lated systems which are involved in any project em-
ploying wastewater or wustewtilcr sludge application
to the land can not be looked upon as a substitute for a
full understanding of system response prior to project
commitment. The role of an on-going monitoring
program should be to confirm judgments made at the
design stage and where inadequate information is cur-
rently available to assure with reasonable certainty the
nature of system response adequate safeguards must
he provided.
Data is presented representing an overview of cur-
rent effluent and wastewater sludge quality at Michi-
gan municipal wastewater treatment plants. Addition-
ally model guidelines being used in Michigan for
groundwater monitoring associated with on land dis-
posal systems are presented.
Monitoring Objective to
Confirm Predictions
The term monitoring denotes the process of ob-
serving, checking, keeping track of ... and as applied
to the area of land application of municipal effluent
and sludges, from the regulatory agency perspective,
it implies confirming the predictions and judgments
made at the project development and design stage.
Monitoring includes the observation of system per-
formance, checking the quality of affected natural
systems, such as the underlying groundwater, and
keeping track of environmental impacts as quality
changes occur. The results of such monitoring should
produce no surprises! The information obtained
should be fully consistent with the predictions of the
project designer as agreed to by the reviewing
authority.
Acceptance of this premise establishes more firmly
the need for a complete understanding of how the
system will respond before commitment is made to a
particular design. For example, the hydrogeologic
performance of a land irrigation system must be
established at the design stage relative to ground-
water mounding, direction and rate of lateral move-
ment of the applied wastewater, and anticipated
water quality changes at given locations, before the
judgment is made that such a system is acceptable.
After construction and operation of the facilities, the
performance of the system is monitored to confirm
these judgments. Again we emphasize that there
should be no surprises.
Areas of Concern
The use of our land resource for waste renovation
or disposal as an alternate to past similar uses of our
water and air environment highlight the need for
avoidance of the "mistakes" of the past. We are aware
of the impact of nutrients in our lakes and streams, of
DDT and mercury in our fish. These conditions re-
sulted from past "mistakes", and we must assure that
we are looking ahead adequately at potential prob-
lems with respect to land use for waste treatment and
disposal. The questions of groundwater system con-
tamination, metallic or other toxic residue build-up
in soil systems, food chain transfer of such materials
183
-------
184
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to animals or man must be answered. We know that
many of these questions are being answered by on-go-
ing research and by efforts such as will grow out of
this conference. These are questions to be resolved
before project commitment rather than as a result of
after-the-fact monitoring.
In Michigan some fifty projects are either in opera-
tion, under construction or planned which will utilize
some form of wastewater effluent application to the
land. Additionally, based on 1969 inventory of sludge
disposal practices within the state, over 200,000 tons
of wastewater sludge are generated each year. This
sludge accumulation will greatly increase in the com-
ing years with higher water quality standards and im-
proved wastewater treatment methods. The vast ma-
jority of the sludge is incinerated at present, but if ef-
fective and economical alternatives are demonstrated
changes in utilization or disposal practices will
follow.
The quality of this liquid effluent and sludge in
terms of its potentially detrimental constituents must
be considered early in the development of alternative
treatment or utilization proposals. A sampling of
sludges and liquid effluent from some 55 communities
around the state during 1973 shows a wide range in
quality as indicated in appendix Tables 1 and 2.
These results represent a single sample survey of
existing conditions and should, of course, be viewed
as a general representation of variations in quality
which may occur in wastewater treatment facilities
under current conditions. The impact of constituents
such as those measured in the survey on proposed uti-
lization or disposal practices involving land applica-
tion must be clearly understood. Effects to be ob-
served or monitored after land application practices
are employed should be readily predictable.
APPENDIX A
TABLE 1
Wastewater Effluent Assay
MUNICIPALITY
§
0;
TEST
PARAMETER
ph
'DIS. Hg
Tot Hg
Dis. Cr
Tot Cr
Dis. Cu
Tot. Cu
Dis Ni
Tot. Ni
Dis. Zn
Tot. Zn
Dis Cd
Tot Cd
Dis. Ph
Tot. Ph
Dis Fe
Tot. Fe
Tot. As
Tot Ca
Tot. Mg
Tot. Na
Tot. K
oa 1242
^ 1254
°- 1242.1254
Phthalate
ADRIAN
8.2
<0.2
<0.2
<0.01
0.02
0.02
0.02
0.10
0.10
0 11
0.18
<001
. kj
> """
UJ K
CQ (S)
7.6
<02
<0.2
OO4
0.12
005
0.08
080
0.80
0.50
0.70
<0.005
0.005
<0.02
<0.02
0.1
04
0.005
48.63
1722
52.3
76
—
0.20
—
3.0
^
5
CO
<0.2
07
0.01
0.02
0.02
0.06
<0.02
<0.02
0.06
0.42
< 0.005
0.005
0.07
0.07
0.21
27
—
76.42
24.69
126.3
17.3
....
—
0.33
2.0
s
T
7 1
<()2
<02
0.02
0.03
001
001
0 13
0.13
0.04
0.05
<0.01
<0.01
<0.02
<002
0.05
08
0007
30.2
1021
51 3
128
053
15.0
NOTE All units nig' 1 except pH and Hg; Hg expressed as fXg/ 1; PCB 1242:1254 ratio 1.1
-------
MONITORING CONSIDERATIONS
185
TABLE 1: (Continued)
MUNICIPALITY
TEST
PARAMETER
PH
Dis. Hg
Tot. Hg
Dis. Cr
Tot. Cr
Dis. Cu
Tot Cu
Dis Ni
Tot. Ni
Dis Zn
Tot Zn
Dis Cd
Tot. Cd
Dis Ph
Tot. Pb
Dis Fe
Tot. Fe
Tot. As
Tot. Ca
Tot. Mg
Tot Na
Tot K
05 1242
4
0.01 1
54.72
13.61
60 1
135
—
0.28
5.0
UJ
•j
-j
s
1
<0.2
<0.2
0.02
0.02
0.03
0.04
'0.02
«0.02
004
0 13
«()(X).5
0(X)5
•002
0.20
0 12
22
58.22
15.05
1382
12.0
....
0 1
....
« 1 0
Q
UJ ^
il
•^
-^
£
76
<0.2
02
0.01
004
006
0,07
0 14
0 16
0 15
025
«0
-------
186
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 1: (Continued)
MUNICIPALITY
TEST
PARAMETER
PH
Dis. Hg
Tot. Hg
Dis. Cr
Tot. Cr
Dis. Cu
Tot. Cu
Dis. Ni
Tot. Ni
Dis. Zn
Tot. Zn
Dis. Cd
Tot. Cd
Dis. Pb
Tot. Pb
Dis. Fe
Tot. Fe
Tot. As
Tot. Ca
Tot. Mg
Tot. Na
Tot. K.
OQ 1242
O 1254
*• 1242 1254
Phthalate
K 5
§
7.4
<0.2
0.7
0.02
0.06
0.04
0.05
0.15
0.17
0.1
0.33
<0.005
<0.005
0.03
017
0.12
0.78
0.007
42.43
15.49
112.5
7.9
—
0.16
—
7.0
GLADSTONE
I
....
0.3
—
<0.01
—
0.04
—
"0.02
—
0.19
—
<0.005
—
<0.02
—
1.5
0.0063
72.89
14.36
48.0
11.8
0.44
—
4.0
GRAND HA VEN
7.6
<0.2
0.7
1.0
1.46
0.42
0.56
0.50
0.56
0.44
1.6
< 0.005
<0.005
0.02
0.16
0.20
2.6
0.005
35.94
13.04
43.4
5.8
—
<0.1
—
11.0
1
GRAND RAPIDS
7.5
<0.2
0.2
0.01
0.46
0.11
0.28
0.46
0.78
1.7
3.5
<0.005
<0.005
0.02
0.14
0.04
5.8
<0.005
55.58
15.05
142.1
7.6
—
1.05
—
17.0
HOLLAND
1
7.6
<0.2
0.2
<0.01
0.01
0.02
0.02
0.06
0.06
0.05
0.09
<0005
<0.005
<0.02
<0.02
0.08
0.14
<0.005
56.90
14.87
61.2
7.6
—
<0.1
—
1.0
•*5 ^"
~s ^
....
0.3
—
0.005
—
0.04
—
<0.02
—
0.12
—
«0005
—
002
—
0.47
<0.005
40.24
768
192
39
—
0 18
—
<1 0
1
1 1TJMOH
7.4
<0.2
<0.2
0.02
0.34
0.01
0.01
0.02
0.02
0.1
0.1
-------
MONITORING CONSIDERATIONS
TABLE 1: (Continued)
MUNICIPALITY
TEST
PARAMETER
pH
Dis.
Tot.
Drs.
Tot.
Dis.
Tot.
Dis.
Tot.
Dis.
Tot.
Dis.
Tot.
Dis
Tot.
Dis.
Tot.
Tot.
Tot.
Tot.
Tot.
Tot.
02
o
0.
Hg
Hg
Cr
Cr
Cu
Cu
Ni
Ni
Zn
Zn
Cd
Cd
Ph
Pb
Fe
Fe
As
Ca
IVIg
Na
K
1242
1254
1242:1254
IRON WOOD
—
—
<0.2
—
-------
188
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 1: (Continued)
MUNICIPALITY
§
1
UJ
H
t~
2;
5
i
^
k.
a:
1
: 2:
s *v
IEST
PARAMETER
pH
Dis. Hg
Tot. Hg
Dis. Cr
Tot. Cr
Dis. Cu
Tot Cu
Dis. Ni
Tot Ni
Dis Zn
Tot. Zn
Dis. Cd
Tot Cd
Dis. Ph
Tot. Ph
Dis. Fe
Tot. Fc
Tot. As
Tot Ca
Tot. Mg
Tot. Na
Tot. K
ffl 1242
0 1254
°- 1242:1254
Phthalatf
«^
UJ
....
—
<0.2
—
<0.005
0.04
—
<0.02
0.03
<0.005
0.02
1.9
<0.005
83.09
20.86
31.8
8.1
—
0.57
-------
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
189
TABLE 1: (Continued)
TEST
PARAMETER
pH
Dis. Hg
Tot. Hg
Dis. Cr
Tot. Cr
Dis. Cu
Tot. Cu
Dis. Ni
Tot. Ni
Dis. Zn
Tot. Zn
Dis. Cd
Tot. Cd
Dis. Pb
Tot. Pb
Dis. Fe
Tot. Fe
Tot. As
Tot. Ca
Tot. Mg
Tot. Na
Tot. K
a 1242
U 1254
ft. 1242:1254
Phthalate
1
Z
7.4
<0.2
0.2
-------
190
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 1: (Continued)
MUNICIPALITY
II. ST
PARAMETER
pH
Dis. Hg
Tot. Hg
Dis. Cr
Tot. Cr
Dis. Cu
Tot. Cu
Dis. Ni
Tot. Ni
Dis. Zn
Tot. Zn
Dis. Cd
Tot. Cd
Dis. Pb
Tot. Pb
Dis. Fe
Tot. Fe
Tot. As
Tot. Ca
Tot. Mg
Tot. Na
Tot. K
a 1242
O 1254
a- 1242:1254
Phthalate
i
|
^"
*>
—
....
•0.02
•0.01
—
0.04
....
•0.02
—
0.19
—
•0.005
—
0.05
—
0.40
•0.005
187.45
9.13
43.9
5.7
0.31
—
•1.0
5
k!
5
*
*-
7.5
«0.2
•0.2
•0.01
0.01
0.02
0.02
<0.02
<0.02
0.21
0.15
0.005
O.005
0.02
0.06
0.08
0.16
0.005
49.73
18.49
67.1
62
....
•0.1
—
1.0
X
LI
1
£
6.6
<0.2
0.2
«0.01
O.01
0.02
0.02
<0.02
•0.02
0.09
0.10
O.005
•0.005
•0.02
•0.02
0.05
0.70
•0.0045
42.75
11.75
43.4
8.3
—
•0.1
—
•1.0
1
u;
£
7.8
«0.2
0.2
0.01
0.02
0.04
0.10
0.04
0.05
0.06
0.18
<0.005
0.01
<0.02
0.10
0.10
2.4
•0.005
95.19
15.93
122.4
19.9
—
«0.1
—
•1.0
5
ce
•T
i
8.2
•0.2
•0.2
0.03
0.10
0.01
0.05
0.4
0.4
0.12
0.27
•0.005
0.025
•0.02
•0.02
0.10
0.60
QNS
52.64
13.70
— .
—
•0.1
—
1.0
h-
^
L1
X
^
9.3
0.2
0.2
0.03
0.55
0.08
0.18
0.04
0.04
0.27
0.85
0.04
0.09
•0.02
0.12
0.2
13.0
0.007
55.91
18.82
142.1
9.7
—
0.40
—
12.0
1
£
^
7.3
•0.2
0.4
0.15
0.64
0.15
0.30
0.86
1.3
0.10
0.37
•0.005
•0.005
0.02
0.06
0.06
1.2
0.005
28.71
6.61
44.4
7.7
—
0.22
—
4.0
|
£
x-
—
•0.02
•0.02
0.01
0.17
0.08
0.10
0.42
0.47
0.25
0.70
0.02
0.03
•0.02
0.05
0.05
0.62
—
57.89
23.85
110.4
66.2
—
0.31
—
2.0
NOTE: All units mg/ L except pH and Hg; Hg expressed asjig/1; PCB 1242:1254 ratio 1:1
QNS - Quantity Not Sufficient
-------
MONITORING CONSIDERATIONS
101
TABLE 1: (Continued)
MUNICIPALITY
I'ARAMI IT K
pll
Pis llg
lol llg
Pis Ci
lol Ci
Pis C'U
lot Cu
Pis Ni
lot Ni
Pis 7.n
1 01 /.n
Dis CM
Tot. CM
Pis Ph
Tot Ph
Pis Fe
Tot Fe
Tot As
Tot Ca
Tot Mg
Tot Na
Tot K
ffl 1242
U 1254
^ 1 242 1 254
Phtlulatc
-02
"0.2
0(M
0.10
002
002
<0.02
«0.02
009
0 14
«().(XXS
<0005
-0.02
<002
0 10
0.40
—
35 03
1055
XI. 2
92
-0 1
—
<1 0
•02
<02
001
0 30
001
001
<002
<0 02
006
0 13
<0005
<0 (X)5
<() 02
<0.02
0.05
006
3594
11 86
77 1
9.1
<() 1
_-~
<1 0
All
units nig/ I except pH and Hg; Hg expressed asjAg/ I, PC'U 1242.1254 ratio
I I
-------
192
APPENDIX B
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE!
Wastewater Sludge Assay
MUNICIPALITY
lc\l
I'tlHIIIH'ICI
STAGE
<"r Solids
Hg
Cr
Cu
Ni
Fe
Zn
Cd
Pb
As
Noie All units
Except 7r
3
T
C
5.6
2.0
3800
2600
1440
14000
4800
260
520
6.0
rng/ kg (air dry
Solids
:>
*
c
32.0
2.7
500
260
14
11000
32(X)
48
240
6.0
basis)
1
^
••T
E
56
3.7
106
310
30
401XX)
480
4
86
7.0
Stage
i i*
•S' ^ ~ | * s
^ -i I •§ •§ ^
* 1 J* I C
E E B C C
68 26 3.7 .08 40
.60 1.0 7.0 42
1840 24(X) 4600 MX)
1260 7(X) 1360 7(X)
1240 460 1500 280
25(XX) 22(XX) 22000 ONS 23IXX)
1420 1640 128(X) 1380
80 8 220 V}
140 320 540 5(X)
6.5 6.8 110 5 9
A. Undigested liquid sludge ONS - Quantity Not Sufficient
B. Primary digestor sludge
C. Secondary digestor sludge
D. Aerobic digestor sludge
E. Vacuum Filter cake
F. Centrifuge cake
G. Drying bed cake
H. Ash classification
M U N 1 C 1 P A L II Y
7csf
STAGE
' '< Solids
Hg
Cr
Cu
Ni
Fe
Zn
Cd
Pb
As
_|
o
_
13
43
52
1600
50
14000
1800
14
340
7
|
0
G
27
3.0
88
300
20
17200
1600
16
400
4
S
1
E
31
1 2
3200
1060
1420
50000
3100
92
880
8.5
1
C
13
16
1,72
540
48
22000
1480
36
340
16
1
E
21
0.9
200
480
24
60000
860
6
200
7
1
C
7.7
3
680
740
20
1280
2600
10
1100
94
^
B
30
1 4
7200
290
1 10
2(XXX)
52(X)
4
174
6.5
-
A
69
26
1080
540
650
I42(X)
4(XX)
20
26(XX)
3
-------
MONITORING CONSIDERATIONS
193
TABLE 2: (Continued)
M 11 N 1 ( 1 l> A I.I 1
Piinmu'tcr
Stage
r/c Solids
Hg
Cr
Cu
Ni
Fe
Zn
Cd
Ph
As
' (
I'tiiamettr
STAGE
r/( Solids
Hg
Cr
Cu
Ni
Fe
Zn
Cd
Ph
As
Tt-\i
PamineU'r
STAGE
r/f Solids
Hg
Cr
Cu
Ni
Fe
Zn
Cd
Pb
As
1
25
11
28
420
20
6800
1080
4
240
3.8
1
3
S
~
e
E
46
2.2
28
580
20
36000
840
4
340
2.8
1
§
C
19
3.0
220
460
<20
16400
1800
4
520
8 1
I
1
16
6.5
1380
920
200
4400
3200
14
600
4.0
a
X
G
9.0
7.0
52
700
20
13000
156
8
280
3.4
c
^
E
56
5.4
60
400
12
9600
660
10
300
10
>
6
E
29
3.2
10600
2600
2800
60000
9400
480
30(X)
90
M 11
S
~~^
^
C
6.7
1.9
9600
720
1200
26000
6800
520
560
17
M
<§.
§
E
36
1.2
66
460
14
62000
660
2
80
11.
-a
F
44
2.6
90
206
«20
9200
I860
10
240
5.
N 1 C 1 l> A L 1 I
1
£
"X*
*
E
40
2.4
1260
700
520
4400
1760
12
340
5.5
U N 1 (.' 1 P A L 1
£
^
19
.4
60
140
40
18000
2600
8
180
5
Y
~z
H
59
> .\
120
3(X)
<20
601XX)
9(XX)
12
240
6
Y
S
^
J
33
2.0
940
1900
1060
36CXX)
3200
40
9(X)
10
T Y
\*>
§
C
14
52
64
500
»20
18000
2000
12
2400
8
HoiialitiHi-Huiuock
D
22
9
76
960
40
12200
760
4
740
1 6
§•
2
~
S
C
21
3.4
22
580
620
11400
1200
4
400
5.9
S
S3
(X
g
£
§
C
11
7.5
62
840
40
15600
2200
14
400
8
k
6.4
30
3IXXX)
9
-------
194
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
TABLE 2: (Continued)
I'tiiiiimifi **
ST-UU- C'
'• Solids 7.1
He. 3 0
C'r 1920
C'u 1()4(X)
Si 480
Fe 44CXX)
Zn 6800
CM 14
Pb 1 2400
\s 18
|
1'iininu'tcr ^
STAGE C
r; Solids 14
He 8.2
C'i 28
C'u 820
S, 20
Fe 1 1000
7n 1 1 20
CM 4
Pb 1 280
\- 72
r
=*
C
1.7
3.0
340
700
20
13400
1120
2
900
5.6
C
*
s
G
14
3.5
900
500
20
10000
4600
44
3600
1.8
M U N 1C 1
8
^
C
10
10
2100
600
100
18000
5400
1100
1560
4
MUNI
C
C
^
C
5.4
8.5
52
1100
<20
28000
1560
10
420
10
MUNI
PA LIT Y
a;
£
3
£
E
21
2.0
360
680
260
24000
2800
8
420
10
( i r A 1. 1 i
I
f.
A
3.4
1.5
380
2(X)
108
40000
1460
8
150
9.0
C 1 1' A L 1 1
•5
uj
£
c
8.4
2.0
360
940
420
20000
2800
12
620
II
Y
$
=
A
43
3.4
3100
1740
740
21000
3800
110
400
9.0
V
S
£
G
49
3.0
440
4800
20
3200
11000
8
720
7.0
|
i
=
E
23
3.4
2500
820
66
36000
3500
280
500
8.0
r
*
h
70
27
124
84
52
14000
740
48
154
10
5
~
h
25
072
56(X)
24(X)
2400
I92(X)
2200
14
480
8
1
*
B
16
32
44
600
20
9000
72
2
480
4 1
3
-
A
6.6
1 4
1800
340
640
13200
8400
166
2300
10
R.
S
STAGE
f'' Solids
Hg
O
C'u
Si
Fe
/n
( d
Pb
\s
A
5.3
I 2
7800
360
90
44000
5000
6
1400
7.5
A
4.6
2 I
66
240
44
144000
900
6
300
16
-------
MONITORING CONSIDERATIONS
APPENDIX C
Ground water Monitoring Guidelines on
Land Waste Disposal Facilities
Monitoring Objectives
The function of a groundwater monitoring pro-
gram for proposed land disposal facilities is to con-
firm judgments made during design. This is to be ac-
complished by a continuing long-term in-depth
hydrogeologic study regarding the performance of
the system and its influence on surrounding ground-
water conditions. This applies to:
1. Wastcwater treatment lagoons
2. Wastcwater storage lagoons
3. Land irrigation systems
4. Large subsurface disposal fields
5. Wastewater sludge disposal sites
6. Industrial waste concentrates disposal sites
At all such existing sites groundwater monitoring
programs are needed to determine the influence of
disposal practices on the groundwater resource.
Design of Monitoring Wells
Monitoring wells must be designed and located to
meet the specific geologic and hydrologic conditions
at each site. Consideration must be given to the fol-
lowing:
1. Geological soil and rock formations existing at
the specific site.
2. Depth to an impervious layer.
3. Direction of flow of groundwater and antici-
pated rate of movement.
4. Depth to seasonal high water table and an indi-
cation of seasonal variations in groundwater
depth and direction of movement.
5. Nature, extent, and consequences of mounding
of groundwater which can be anticipated to oc-
cur above the naturally occurring water table.
6. Location of nearby streams and swamps.
7. Potable and nonpotable water supply wells.
8. Other data as appropriate to the specific system
design.
Groundwater quality should be monitored immedi-
ately below the water table surface near the applica-
tion site as pollutional materials entering the ground-
water system may have a tendency to remain in the
upper few feet. Applied wastewater will generally be
depressed within the groundwater system as the ma-
terial travels away from the site. The need for sampl-
ing at more than one depth within a groundwater sys-
tem will depend upon geologic conditions and dis-
tance from the pollutional source and definition of
the flow system with depth will be necessary to prop-
erly determine the depth to be monitored, especially
195
when mounding is superimposed on the existing svs-
tem.
Additional design and construction considerations
are:
1. Monitoring wells in fine textured soils will re-
quire special construction such as gravel packing
around the screen.
2. Wells constructed to a depth of 20' or more
should be 4'' in diameter to facilitate use of sub-
mersible pump equipment for sample collection
unless alternative sampling methods are ap-
proved by the reviewing agency.
3. Construction should be by a registered well
driller or contractor covered under Act 315, PA
of 1969 using approved modern construction
methods.
4. Casings shall be grouted and capped
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196
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
4. Monitoring wells should be installed early in the
construction sequence and monthly water level
readings obtained during the construction period
and during the first two years of wastewater sys-
tem operation to provide background informa-
tion. Subsequent water level measurement fre-
quency should be in accordance with a schedule
established on a case by case basis.
5. All wells should be securely capped and locked
when not in use.
Water Sampling
Background water quality. A minimum of three
monthly samples should be collected from each
monitoring well prior to placing the storage or dis-
posal facility in operation. In cases where back-
ground water quality adjacent to the site may be in-
fluenced by prior waste applications, provision of
monitoring wells or analysis of water quality from
existing wells in the same aquifer beyond the area of
influence will be necessary.
Operating Schedule. Samples should be collected
monthly during the first two years of operation. After
the accumulation of a minimum of two years of
groundwater monitoring information, modification of
the frequency of sampling may be considered upon
written request.
Sample Collection
1. A measured amount of water equal to our great-
er than three times the amount of water in the
well and/or gravel pack should be exhausted
from the well before taking a sample for analy-
sis. In the case of very low permeability soils the
well may have to be exhausted and allowed to
refill before a sample is collected.
2. Pumping equipment shall be thoroughly rinsed
before use in each monitoring well.
3. A pressure tank shall not be used with a sampl-
ing system since the water in the pressure tank
would be particularly difficult to exhaust.
4. Water pumped from each monitoring well
should be discharged to the ground surface away
from the wells to avoid recycling of flow in high
permeability soil areas or soil erosion.
5. Samples must be collected, stored, and transpor-
ted to the laboratory in a manner so as to avoid
contamination or interference with subsequent
analyses.
Sample Analysis
Water samples collected for background water
quality should be analyzed for the following: (Note:
Parameters for groundwater monitoring at industrial
waste disposal sites must be established on an in-
dividual basis depending on the composition of the
wastes applied).
1. Chloride
2. Specific Conductance
3. pH
4. Total hardness
5. Alkalinity
6. (a) Ammonia nitrogen
(b) Nitrate nitrogen
(c) Nitrite nitrogen
7. Total phosphorus
8. Methylene blue active substances
9. Chemical oxygen demand*
10. Any heavy metals or toxic substances found in
the applied wastes.
After adequate background water quality informa-
tion has been obtained, a minimum of one sample per
year, obtained at the end of the irrigation season in
the case of seasonal operations, should be collected
from each well and analyzed for the above constit-
uents.
All other water samples collected in accordance
with the operating schedule should be analyzed for
chlorides and specific conductance as indicators of
changes in groundwater quality resulting from the
wastes applied. If significant changes are noted in
chloride and/or specific conductance levels, samples
should immediately be analyzed for the other para-
meters listed above to determine the extent of water
quality deviation from background levels.
Groundwater Monitoring System Reports
Well location plan. The owner of the system is to
provide a plan, drawn to scale, showing the location
of each monitoring well and its relationship to the
wastewater treatment lagoons, storage lagoon, irriga-
tion area, sludge disposal site or subsurface disposal
field and to other significant features such as munici-
pal or private wells, surface streams, etc. It is sug-
gested that individualized well location plan maps be
prepared by the project consultant. The plan map
shall include casing elevation information to facili-
tate conversion of water level measurements to datum
elevations.
Reports. The owner of the system is to file stand-
ard reports of observations and sample analyses, ob-
tained in accordance with the schedule listed above,
with the responsible state agency within 30 days of
sample collection. Notification of significant devia-
tions from background quality is to be given im-
mediately.
* Use of low concentration C.O.D analysis methods per current
edition of Standard Mctlvxls may be necessary
-------
MONITORING CONSIDERATIONS
DISCUSSION
QUESTION: Robert Dean, EPA. Are you going to
apply different standards to spreading of effluent on
the land than you apply to the workers who have to
work in the conventional sewerage treatment plants
today, with regard to spray and things like that.
ANSWER: I think that as we get into these kinds
of questions, we have to deal with all of the alter-
natives and I think there are some serious questions
that have to be addressed and have to be answered.
We talked about the various alternatives for different
disposal methods, stack emissions from incineration
should be zeroed in on and given the same kind of
emphasis that we are giving these considerations here.
It is simply a matter as I see it right now of too many
questions to be asked to get answers to all at once.
We are using this forum right here to answer some of
the questions. There are a lot more to be answered.
QUESTION: Robert Schneider, Office of Water
Resources Research. First, is monitoring a legal
regulatory requirement in Michigan? I am thinking in
particular of the effluent in ground water or in
streams. Second, you mentioned that the chemical
quality of sludges varies considerably and also that
the purpose of the monitoring or the general objec-
tive is that monitoring should result in no surprises.
Now, how could you differentiate between changes in
quality resulting from surprises and those changes
that result in changes of quality of the sludge?
ANSWER: Let me see if I can get them in order.
Let me deal with the changes and the surprises thing.
We are trying to emphasize that there has to be a very
detailed look at the project as a whole before we get
into commitment to it.
Per se there is no statute that says thou shall
r.ionitor ground water given projects. It is an ad-
ministrative type action that we, as the state
regulatory agency, are implementing. We recognize
that we are deficient, we are slow in getting this kind
of a program underway in that we have had lagoon
systems in the state for 10 and 15 years that have
never filled up. It never went out to the stream the
way it may have been designed. So now we are going
back and taking a look at the ground water systems
and this is going to be a significant task to go back to
these communities, knock on the door and say hey,
we missed something, let's check and see whether or
not we got some detrimental impact here in the
ground water. We are looking at monitoring on any
new project as an intrical part of the development of
project and some projects are going to be far more
complex than others and some systems a type sur-
veillance and so on. We may be able to dismiss it
quite quickly.
QUESTION: By George Ward, Portland, Oregon.
Darwin, I would like to ask you one. Could you give
us generally the Washington EPA's opinion on finan-
cing of sludge incinerators, if there is one, and then
also is there anyone in the audience or speakers left
that cares to talk about known or suspected hazards
of sludge incineration.
ANSWER: Darwin Wright, EPA. We did have a
task force on incineration and we have completed a
report. We recognized that there are some air
pollution problems with incinerators, but I know that
there are some groups that are going ahead, Blue
Plains is building some rather large incinerators.
ANSWER: John Trax, EPA. I think one of the
critical problems identified in this task force was the
PCB's, and what happens to them when they are in-
cinerated. We don't know very much about this We
realize that there is a lot of work to be done in terms
of determining the health effects as related to in-
cineration of sludge and refuse or a joint incineration
of sludge and refuse. We don't have any projects
initiated to look at these problems. Maybe Bob Dean
has something to add to this.
ANSWER: Bob Dean, EPA. On the incinerator
approach, I have taken the attitude for ultimate
disposal that incineration is one of the acceptable
ways of disposing of wastes or at least reducing the
organic content and I have also found that it is very
often not the most cost effective method. If you put
on all the necessary controls. Now, incinerators can
be operated to meet extremely strict controls and
they are so operated in the State of California, in the
San Francisco Bay region. Now, Los Angeles region
has taken the attitude that they don't think an in-
cinerator could ever meet the code that they will get
around to writing, but this is sort of discouraging to
anybody who wants to build an incinerator.
However, incinerators can meet the codes. The PCB
problem arose from the fact that we couldn't find
PCB after the sludge had been incinerated and we
knew it was there and we didn't see how it could have
gotten away because when pure PCB's are in-
cinerated under those same conditions, they surely
would have gotten out. But there has been some more
recent work not yet substantiated but we are working
on it, that shows as long as there is something else
burning at the same time, the PCB's aren't all that
hard to get rid of.
I have another rather interesting fact. The task
force that John is referring to, mentioned levels of
PCB's including one city where they made them, of
over 105 parts. I would like to get this in the record.
Against a national background of around three. That
corresponds to the geometric mean. Eighteen months
-------
198
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
later it is down closer to 20 than it is to 100 after the
voluntary phasing out of PCB's in business forms.
Furthermore, two local plants in Cincinnati that have
been up in the 20 to 30 range, probably because they
were re-pulping a lot of paper to make packing car-
tons, are now down in the three to five range, about
where you would expect the rest of the country to be.
So, it looks like the voluntary controls on PCB's are
being effective in most areas. We still find a few
places that have high PCB and we want to trace one
down, maybe somebody is salvaging copper from old
transformers, you know you are allowed to use PCB's
in transformers, but you are suppose to be careful
how you scrap them, and they do burn up every once
in awhile too. So, maybe the PCB's aren't so bad.
I think my message is you can use incineration but
you have got rather expensive controls and quite a lot
of energy used and that cost has to be recalculated as
the cost of energy starts to go up.
-------
Institutional Options
for Recycling
Urban Sludges
and Effluents
On Land
ROBERT R. BARBOLINI
Metropolitan Sanitary District
of Greater Chicago
ABSTRACT
Analysis of institutional options for recycling efflu-
ents and sludges from urban wastewater treatment
plants on land indicates the presence of numerous al-
ternative methods for financing, operating, and or-
ganizing large scale programs. The effects of technical,
social, political and legal constraints are examined
and found to be significant in the determination of
preferred alternatives.
I'he experiences of the Metropolitan Sanitary Dis-
inct oj drearer Chicago (MSDGC) are extensively
used lo illustrate available institutional options. The
MSDCiC IMS been active in land application of sludge
iind /s currently engaged in a very large scale project
to apply sludge to rural, stripmined land approximate-
ly 200 nn/es from the center of its collection and
treatment activities
Preferred methods oj financing are bond sales or
Slate and federal grants for capital improvements,
and current taxation for normal maintenance and
operation activities. The preferred alternate for opera-
tion of land application facilities is believed to require
the purchase of large rural tracts. Land development
must be achieved through careful planning activities
Conducted with close cooperation between local
government agencies of the rural receiving area and
the urban producing area. There exists an urgent need
tor State and Federal conceptual commitment, and fi-
nancial and technical assistance to land application
programs.
INTRODUCTION
The problems associated with land application of
urban sludges and effluents have been well documen-
ted in technical journals as well as in the popular
media. Numerous articles outline the dimensions of
the problem, characterize various sludges and efflu-
ents, and describe the land selected to dispose of
those materials. The literature dealing with land ap-
plication contains a significant information relative
to the plants to be cultivated in such agricultural
operations, and documents the relationships between
those plants and the components of the sludges and
effluents used to nourish them. Not so well docu-
mented, however, are certain practical problems
dealing with the options available to an agency or in-
stitution for implementing a large scale land applica-
tion program. As with any program, operational, fi-
nancial, political and social alternatives are avail-
able.
The Metropolitan Sanitary District of Greater
Chicago (MSDGC) has been active in the area of land
application of digested sewage sludges since the mid-
1960's. It is the purpose of this paper to draw heavily
from the experiences of the MSDGC in order to de-
scribe and discuss some of the alternatives available
199
-------
200
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to an organization undertaking a program of applica-
tion of sludges and effluents to the land.
Financial Alternatives
The financial alternatives available for any large-
scale program of land application are, in general, the
same as those normally available to the sludge-efflu-
ent producing agency to satisfy its other long-term
and short-term economic resource requirements. Al-
ternative means of financing are:
a. Sale of bonds
b. Current taxation
c State and Federal Grants
d. Sale of sludges and effluents
The MSDGC has used bond sales, current taxation
and State and Federal grants to finance portions of its
land application programs. The MSDGC has not, as
yet, been successful in selling liquid sludges to gen-
erate income. The alternative of financing the land
application of sludge or effluents by their direct sale
to farmers or other buyers must probably be dis-
counted at this time due to the fact that use of these
materials has not been perceived by individual farm-
ers as being economically desirable. Much technical
and promotional development will be required before
liquid sludges and effluents can be successfully mar-
keted. However, the basic capability of sludges and
effluents to provide necessary nutrition and irrigation
to agricultural lands may in time overcome current
attitudes and beliefs which, in part, preclude com-
mercial sales at this time. It is entirely possible that in
future years sludges and effluents will be in demand
by agricultural interests and that this new market will
provide at least a part of the revenue required to de-
liver and apply the materials to the land.
Financial alternatives may be used either to the ex-
clusion of each other or to supplement each other. In
general, bonds are sold to obtain funds to pay for
large new capital improvements and current taxation
is used to pay for relatively constant, recurring costs
associated with normal maintenance and operation. It
\\ould appear that land application programs do not
possess any characteristics which would cause the se-
lection of financial options to be made in a manner
different from that normally used in any construction
and operation program. If land for the application
program is purchased, funds would be available from
the sale of bonds. However, if land is leased, the
necessary funds may have to be generated from cur-
rent revenue. Improvements to the land such as grad-
ing, construction of berms, dikes, reservoirs, holding
basins, and monitoring wells will almost invariably
be paid for by funds generated by the sale of bonds.
Likewise, pipelines, pumps, aeration units and other
process equipment required both in the application
fields and in the plant, which is the source of the
sludges and effluents, will be purchased and installed
with bond generated funds.
Various methods of transporting sludges and efflu-
ents from their source to the application site must be
considered. It is very difficult, if not impossible, to
find suitable land in close proximity to large urban
centers. Therefore, the cost of transportation is likely
to be a large factor in the total cost of a land applica-
tion program. If transportation is provided by award-
ing a contract to a private enterprise, the cost of this
service may be paid in a series of payments based on
quantities shipped. Such payments may he made from
proceeds of current taxation. However, il transporta-
tion is provided by the producing agency itself by
purchasing trucks, rail cars, barges, or a pipeline, the
cost of such capital equipment will probably best be
paid for by proceeds from bond sales. The operating
costs for the transport equipment, like the operating
costs of other system components, would almost cer-
tainly be paid from proceeds from current taxation.
A suitable alternative to bond generated funds are
State and Federal Grants. Such funds are frequently,
although not always nor dependably, available and
are allocated according to such factors are current
appropriations, and State and regional priorities.
By way of example, the MSDGC is currently de-
veloping strip-mined land in Fulton County, Illinois,
approximately 200 miles from the center of its collec-
tion and treatment facilities in Chicago. The MSDGC
considered various alternative transportation sys-
tems, particularly rail and barge, for its initial opera-
tion. Barge shipment was finally selected because of
its greater economy over the time period considered.
Finally, the MSDGC elected to contract for the barge
hauling. The details of the contract are rather com-
plex, but basically the agreement provides for period-
ic payments to be made to the contractor on the basis
of sludge volume shipped. Payments are made from
the revenues obtained from current taxation. How-
ever, the MSDGC has chosen to pay for the capital
improvements required for the land application pro-
gram from the proceeds of bond sales. In addition,
the MSDGC applies for Federal and State grants for
all capital expenditures required for its land applica-
tion program. Such grants have been a significant fac-
tor in overall financing.
Operational Alternatives
A number of operational alternatives for land ap-
plication programs are available to the producing
agency. A partial list of alternatives follows
a. Purchase land, develop and operate.
b. Purchase land, contract development and opera-
tion.
-------
INSTITUTIONAL OPTIONS
201
c. Purchase land, develop and contract operation.
d. Contract land acquisition, development and
operation.
e. Lease land, develop and operate.
f. Lease land, contract development and operation.
g. Lease land, develop and contract operation.
h. Deliver application material to private land-
owners.
In principle, any one of the above alternatives may
he used simply or in combination with each other to
fulfill the basic requirement of delivering and apply-
ing sludges and effluents to the land. However, there
are a variety of social, political, financial and tech-
nical constraints that, in fact, severaly limit one's
freedom of action. Some of the experiences the
MSDGC has encountered in implementing its solids-
on-land program are quite useful in illuminating the
various constraints which apply to some of the alter-
native techniques. The degree to which certain con-
straints apply to some alternatives, but not to others,
is a major factor in determining preferred options.
In the early stages of its land application program,
the MSDGC searched for relatively large plots of
nonproductive soils within its jurisdictional bound-
aries. Very early in the program, conducted within
the borders of the MSDGC, negative public opinion
was encountered. For this reason, the program was
aborted early in its development.
Most of the MSDGC's service area is urbanized.
Even "farm" areas within the borders of the MSDGC
have high population densities when compared to
rural farms. Furthermore, "farm" areas which cur-
rently exist within the MSDGC are rapidly undergo-
ing a contraction as virtually unrestrained suburban
growth causes acreage to be taken out of agricultural
production. The growth of the suburbs acts in two
negative ways to undermine the potential success of a
land application program. First, and most obvious,
the suburbs bring a large influx of people of non-
farm background into a previously agricultural area.
The lack of familiarity of the new suburbanites with
agricultural operations, and their attitudinal inclina-
tion to regard sludges and effluents as undesirable
wastes, make it practically impossible to conduct a
large scale land application program in such areas.
The second way in which the growth of the suburbs
acts to impede the success of land application pro-
grams is by its effect on land values. The economic
viability of a land application program rests heavily
on the availability of relatively inexpensive terrain.
Land prices which prevail in the major agricultural
producing areas of Illinois and other midwestern
states are currently low enough to permit land appli-
cation in an economically acceptable manner. How-
ever, land prices in most suburban areas and central
cities are such that they render land application eco-
nomically unjustifiable. If an outlet from urbanized
areas cannot be found, other alternatives, usually
consisting of processing plants and facilities, must be
considered. Within the highly specialized environ-
ment of large urbanized areas, complex and costly
mechanical and chemical treatment facilities must be
constructed because of economic considerations even
though it is known that such techniques are not as
favorable to the natural ecology of the environment
as recycling processes such as land application. The
conclusion to be drawn from the foregoing is that it is
of paramount importance to a land application pro-
gram that the urban producing agency have access to
large acreages in rural area.
The MSDGC soon came to appreciate the need for
access to rural areas. As the MSDGC has no powers
of eminent domain outside its borders, it reah/cd that
it would have to offer general benefits to runii receiv-
ing areas in addition to simple monetary compensa-
tion to individual land owners in return for their
properties. Accordingly, the MSDGC methodically
began to search for unproductive lands, within a 250
mile radius of Chicago, which could benefit from the
application of sludge. Such lands could be made pro-
ductive, increasing the wealth of the local commun-
ity, while simultaneously providing a needed outlet
for sludges generated in the urban area. It is interest-
ing to view sludges and effluents in the context of
economic resources which are supplied and demand-
ed. The enormous imbalance between supply and
demand in urban areas prevents the formation of a
market in which sludges and effluents can be supplied
at a positive price. Hence, in urban areas, sludges and
effluents are supplied to "buyers" at a negative price,
i.e., suppliers must pay to have the materials removed
from their premises. It is in this context that sludges
and effluents are considered to be wastes. However, it
sludges and effluents can be transported to rural re-
gions, it is at least possible that supply and demand
curves could intersect at a positive value. Of course,
substantial effort is required to stimulate demand
even in rural areas, but it is at least conceivable that
sludges and effluents could become marketable com-
modities in certain regions in coming years.
In late 1970, the MSDGC located strip-mined
lands in Fulton County, Illinois, about 200 miles
from Chicago, which at that time were marginally
productive in an agricultural sense. Working in close
cooperation with the Fulton County Board of Super-
visors, the MSDGC developed its "Prairie Plan", a
comprehensive and detailed program whose salient
character was the emphasis on mutual benefit to both
the receiving area and the donor area. The experien-
ces of the MSDGC in implementing a large scale land
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202
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
application plan in Fulton County are significant, in
that they illustrate many of the problems that in-
fluence a land acquisition program. The MSDGC
would have preferred acquiring cropland instead of
strip-mined land, due to the relatively high costs of
rehabilitating the latter. Strip-mined land is highly ir-
regular, often covered with spoil-banks, and has to be
leveled before use. In general, land application pro-
grams require a closed system to prevent field run-off
from entering streams before sampling can be com-
pleted to assure that water flowing into waterways
meets applicable standards. The design and construc-
tion costs of such closed systems are quite high, gen-
erally greater than the purchase price of the land.
Since the investment in site preparation is large rela-
tive to the purchase price of the land, it is generally
preferable to purchase, rather than lease, land in or-
der to be able to recover development costs in the
event of a later sale of the property. Thus, the
MSDGC has decided to purchase its lands in Fulton
County. The procedure used in the land purchases
was to have the land appraised, enter into negotia-
tions with owners, and finally to consummate the
necessary purchases. Initially, strip-mined land in
Fulton County was valued at $300-350 per acre, but
land values have since risen to $400-600 per acre.
The MSDGC has purchased about 10,000 acres to
date, but this is not enough to fully assimilate, on a
steady-state basis, the large quantities of sludge pro-
duced in the metropolitan Chicago area.
The foregoing description of the MSDGCs current
operations in Fulton County suggests that the
MSDGC has always chosen the operational alterna-
tive of purchasing, developing, and operating upon its
own land. In Fulton County, the MSDGC has indeed
purchased and developed its own land, but a substan-
tial portion of the agricultural operations are con-
tracted to local farmers. Only operations directly re-
lated to the application of sludge to the land are di-
rectly controlled by the MSDGC. The MSDGC has
selected this alternative because it has found that the
lowest long term cost and strictest operational con-
trol can be obtained through this technique.
However, the MSDGC has not always been com-
mitted to the alternative of purchasing and develop-
ing its own land. In 1971 the MSDGC chose to con-
tract for a complete package of land acquisition, de-
velopment, and operation. The MSDGC awarded a
contract on such a basis to remove, transport and uti-
lize liquid sludge in Douglas County, Illinois, about
150 miles from Chicago. The MSDGC's contractor
successfully applied thousands of tons of sludge to
agricultural lands and generally performed in a man-
ner acceptable to the MSDGC. However, the rela-
tively small scale of the operation relative to the
MSDGC's total needs, and the contractor's legitimate
requirement to operate at a profit and provide a con-
tingency against unforeseen circumstances, combined
to result in relatively high unit costs for the land ap-
plication operation.
The final operational alternative to be discussed
here is the option of delivering sludges or effluents
directly to the farmers who would apply them to the
land. This alternative has not been employed by the
MSDGC, but could become a significant option in fu-
ture years. In Illinois, the Illinois Environmental Pro-
tection Agency (IEPA) requires that any person or
organization applying sludges or effluents to the land
do so in accordance with a carefully planned and
documented program and to obtain a State Permit lor
the operation. Presently, farmers are not required to
submit any plans, or to obtain permits, for the appli-
cation of commercial fertilizers. Without substantial
economic subsidy, few farmers would, therefore, be
interested in applying sludge or effluents to their
lands, particularly after consideration of the fact that
commercial products have substantially better fertil-
izer properties per unit weight than do sludges or ef-
fluents. Furthermore, the individual farmer is primar-
ily interested in applying fertilizer at the least cost
and in such a way as to maximize his yield. Applica-
tion of sludges and effluents must be carried out in
relatively small dosages over the entire growing sea-
son in order to avoid uncontrolled run-off and re-
duce soil erosion. In cases where sludges and efflu-
ents are applied directly by farmers the difficulty and
cost of maintaining proper control of the many scat-
tered land areas would be substantial. Manpower
costs for monitoring non-contiguous sites would be
great, and design and construction costs for a multi-
plicity of independent systems would certainly be
larger than for a smaller number of larger systems.
Political Alternatives
The political organization alternatives for large
scale land application programs are:
a. Single local government control.
b. Combined urban government-rural government
control.
c. Regional government control.
d. State control.
e. Federal control.
Single local government control is possible by
either urban or rural local governments. In the case
of urban governments, the above discussion has
described how the growth of suburbs and the high
costs of land tend to prevent the development of a
large scale land application program within an urban
area. It has been concluded that an urban producing
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INSTITUTIONAL OPTIONS
203
agency must have access to large acreages in rural
areas. Also, it is impractical for an urban government
to exercise exclusive control over a land treatment
program in a rural area without the local rural gov-
ernment being given a large share of control. At the
least, the rural government must be granted the de-
gree of control necessary to secure its acquiescence.
On the other hand, it is unlikely that a large scale
land application program could be controlled by a
rural government alone due to insufficient financial
resources.
Combined urban-rural government control ap-
pears to present a practical means to overcome local
rural resistance to acceptance of what can often be a
controversial program. Intensive educational pro-
grams will be required to earn acceptance of the con-
cept of receiving and applying urban wastes on the
land. Formation of a formal association between the
urban and the local rural government serves to foster
acceptance of land application programs. Therefore,
it is believed that the participation of local governing
bodies is indispensable in any program involving dep-
osition of urban materials in rural areas. Although
association between urban and rural government is a
minimum requirement, it is more desirable to find a
means of offering a more active and involved role to
the local government. For example, direct participa-
tion in planning, construction of facilities, applica-
tion of effluent or sludge to the land, monitoring,
farming or some other aspect of the operations could
be undertaken by the rural government. The financial
support for such rural government activity could be
by State and Federal Grants or by contractual ar-
rangements with the Urban partner. Granting a more
active role to the local government in the creation of
parks within the treatment area to provide facilities
for sports and recreational activities is considered es-
sential.
The MSDGC land application program in Fulton
County has been developed with the assistance of a
steering committee comprised of local elected offi-
cials, local citizens, representatives of State and Fed-
eral agencies, MSDGC trustees and staff personnel.
The mutual goals of both the MSDGC and Fulton
County, as well as the comprehensive approach to
site development, were published jointly by the
MSDGC and the Fulton County Board of Supervis-
ors. The steering committee recognized that although
the land in Fulton County was purchased for the pri-
mary purpose of applying digested liquid sludge to
the land, the needs of the local communities would be
integrated into the plan with compatible secondary
goals of recreation, conservation, natural science
education and economic stimulus. The Fulton Coun-
ty Planning Commission has approved the multiple
use planning of MSDGC properties located in that
county. The MSDGC leases over 400 acres of us
property to the Fulton County Board of Supervisors
for development of fishing, camping, boating and pic-
nicking activities. In short, the "Prairie Plan" is an
example of combined urban-rural government co-
operation in the development and management of a
land application program for their mutual benefit.
Regional government control may be useful in
areas where there exists an urban source of effluent
or sludge in proximity to a land area suitable for ap-
plication of these materials. The Muskcgon County,
Michigan, project is of this sort. It is designed to
process almost all the sewered wastewater produced
in that county.
State or Federal control of a large scale treatment
program appears less of a possibility than the types of
control so far discussed. Both the states and the Fed-
eral government are reluctant to assume responsibil-
ity for projects that can be carried out by local gov-
ernments. However, preliminary surveys of five ur-
ban areas have been carried out by the U.S. Army
Corps of Engineers. One of these areas, the Chicago-
Northwest Indiana Region, crosses state boundaries.
To implement a land application program in this re-
gion would almost certainly necessitate the creation
of an interstate regional authority. However, there
would not appear to be any rationale for direct Fed-
eral control.
Legal Constraints Affecting
Alternatives
Land application is not a new idea insofar as
wastewater treatment is concerned. The Chinese have
been fertilizing their fields with "night-soil" for cen-
turies and municipal wastes have been applied to
farmland in Europe since the sixteenth century. How-
ever, the use of treated wastes, as, for example, efflu-
ent from a secondary wastewater treatment plant or
stabilized digested sludge, is a fairly recent practice.
Accordingly, there has been a lack of complete de-
velopment of laws, statutes and legal principles gov-
erning land application activities.
An evaluation of Federal and State laws, standards
and guidelines pertaining to land treatment appears
in "Green Land-Clean Streams", published by the
Center for the Study of Federalism of Temple Uni-
versity. The latter publication reviews the develop-
ment of water legislation bearing on land treatment.
At the time of publication (1972), there was no Fed-
eral water legislation of this type, but many of the
states have had various regulations, guidelines, and
policy statements since the 1930's. Since publication,
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
the Federal Water Pollution Control Act Amend-
ment of 1972 has been passed by Congress and signed
into law. It contains various references to land appli-
cation of sludges and effluents. For example, in Sec-
tion 107, it calls for projects to control mine water
pollution, including techniques of using sewage
sludge materials to restore affected lands to useful-
ness, to be carried out with the cooperation of the
States.
In the State of Illinois, the Environmental Protec-
tion Act of 1969 created the Illinois Environmental
Protection Agency (IEPA) to administer the Act, and
the independent Illinois Pollution Control Board
(IPCB) as a rule-making body. No standards for land
application of effluent or digested sludge appear in
the "Water Pollution Regulations of Illinois." The
Standards Section of the IEPA is currently using the
standards for land treatment published by the Great
Lakes Upper Mississippi River Basin States in Adden-
dum No. 2, 1971 Edition. This Addendum fails to ad-
mit the existence of land treatment facilities of sub-
stantial size, especially outside the GLUMRB region,
and states that "protection of groundwater and sur-
face resources is the major concern in the develop-
ment of guidelines" for the filing of an application for
a permit to operate a land treatment facility. Until
now, the IPCB has specified that the effluent from the
run-off holding basins must meet effluent standards
as given in Part IV of Chapter 3, "Water Pollution
Regulations of Illinois." The IPCB's decision to im-
pose effluent standards on run-off from sludge or ef-
fluent application fields, while not imposing similar
requirements on run-off from normal farm fields, is
criticized by the editors of Temple University's
"Green Land-Clean Streams".
Other legal constraints exist. For example, in the
case of an MSDGC contractor carrying out land ap-
plication of digested sludge in Grundy County,
Illinois, that county attempted to terminate the proj-
ect on the ground that the contractor had failed to
obtain a permit from the County Zoning Board. Since
the zoning regulations explicitly stated that they did
not apply to agricultural facilities, the matter was
brought before the Courts. A decision was rendered
in favor of the land application project, classing it as
an agricultural operation. It remains to be seen
whether or not this decision will bring about a revi-
sion in the IPCB regulations, that now classify run-
off from land application projects as effluent instead
of normal agricultural run-off.
Finally, as exemplified by the IEPA Permit issued
to the MSDGC in connection with the Fulton County
Project, large-scale land application of effluent or
sludge is considered to be a new procedure, still ex-
perimental, and subject to modification or termina-
tion if it results in or threatens to cause pollution of
waters, air or lands, or hazards to water supplies.
Furthermore, the IEPA has stated that it is not in a
position to guarantee the legal validity, under Fed-
eral law, of its permits for the disposal of sludge by
any operation that might "result in any pollutant
from such sewage sludge entering navigable waters".
Thus, land application systems are characterized
by many legal constraints. Development of a satisfac-
tory land application program for effluent or sludge
will necessarily be greatly influenced by the nature
and extent of these constraints.
RECOMMENDATIONS
Land application of effluent and sludge is still in a
developmental stage. Demonstration projects are
required to develop new technology and resolve cer-
tain technical problems. There is a great need for
substantial State and Federal assistance in the area of
research and development. Not only is financial as-
sistance required, but, in order to prevent overlap-
ping and duplication of effort, it would seem appro-
priate for governmental agencies to plan and coordi-
nate research and development, and perhaps, to carry
out such programs under the auspices of existing gov-
ernment institutions. Such agencies have at their dis-
posal resources that are unavailable to even the larg-
est producers of sludges and effluents.
In addition to support of research and development
programs, there is a need for a greater measure of
Federal and State commitment and positive encour-
agement of land application programs. Laws, regula-
tions and guidelines should be revised to facilitate,
not discourage, such programs and should recognize
that they constitute not just an approved method of
treating wastes, but a necessary and preferred
method.
There is a need for comprehensive land use plan-
ning on a state-wide or regional basis. Large tracts of
land could be developed to accommodate numerous
public facilities normally considered undesirable.
For example, airports, land fills, sludge and effluent
application areas and wastewater treatment plants
could be accommodated on large common sites.
These tracts could be made attractive and could up-
grade and preserve local natural environments by
providing public parks and forests, complete with na-
ture paths and camping and recreational facilities.
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INSTITUTIONAL OPTIONS
205
CONCLUSIONS
The problem of sludge and effluent disposal is be-
coming more and more pressing with time. For exam-
ple, as primary wastewater treatment becomes inade-
quate and is succeeded by secondary and then by
tertiary treatment, sludge volumes throughout the
country are increasing. The assistance of the Federal
and State governments will be necessary in develop-
ing adequate land application programs. Land appli-
cation, now in a developmental stage, will require
demonstration projects to introduce new technology,
resolve technical problems, and win public approval.
It has been pointed out that an agency interested in
land application will be most successful when it
operates in a manner acceptable to the local popula-
tion of the receiver area and when it has engaged
local government in direct participation in the proj-
ect. The most significant hurdle in the successful
initiation and operation of a land treatment program
is public acceptance. Also necessary is the ability to
work with a variety of public agencies and competing
interests.
The favored method of handling land acquisition
has been seen to be by purchase, preferably of large
tracts. Acquisition by lease has been found to be gen-
erally undesirable. It would appear that the most
feasible approach is to purchase a sufficiently large
parcel of land to minimize design and construction
costs and the cost of control and monitoring.
As noted, public opinion and the diversity of pub-
lic agencies involved make the success of land appli-
cation programs subject to considerable uncertainty.
Federal intervention may be necessary to provide a
consistent governmental approach to this problem
and make it possible for the land application agency
to free itself, to some degree, of unnecessary uncon-
structive forces.
DISCUSSION
QUESTION Bob Miller, Ohio State University.
Your comments on the prairie plan about the fact
that large treatment systems cannot get the agreement
of the people within the metropolitan system, this is
contrary to what we are finding in Ohio on the Three
Rivers Water Shed Study by the Corp of Engineers.
There it seems that acceptance of effluent disposal on
land within the basin, the Three Rivers Water Shed
is fine, acceptance outside of the basin where one of
the alternative plans designated disposal has met with
a great controversy and probably is not even feasible.
So, I think there are situations that are totally dif-
ferent and each one will have to be handled by itself.
We came to the conclusion that acceptance by people
of their own wastes is better than acceptance of other
peoples waste.
ANSWER: I think I would agree with what you
have to say. I would like to emphasize though, that in
the case of the Chicago system the sludges that we are
applying to the land are certainly outside of the
jurisdiction of the Metropolitan Sanitary District.
They are some two hundred miles away, so here we
are not in a situation that people are not accepting
their own wastes, but they are seen as accepting the
wastes of some other area. But I certainly would
agree that each area should be analyzed on its own
merits.
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Public Acceptance—
Educational and
Informational Needs
JOHN O. DUNBAR
Purdue University
INTRODUCTION
For an idea such as recycling urban sewage and
sludge to the land to be implemented in our society, it
must have public acceptance. It must be acceptable
to the majority of the people. It must be actively sup-
ported by a large enough number of individual lead-
ers so that they can favorably inform the people who
depend upon them and keep those who oppose it in
the minority. It must have enough support by both
private and public groups so that they will use their
organizational, financial, and political strength to
bring about its implementation.
I believe we can all agree that the level of public
support for this idea at this time (July 1973) is a great
deal less than is needed; therefore, we need to devise
ways to raise it. The question we face is how can this
be done most efficiently with our limited resources. It
is a question of changing people's behavior and de-
veloping effective programs to bring it about. There-
fore, the basic problem we are concerned with in this
discussion is how to get people to think, feel, and act
more favorably toward recycling urban effluents and
sludges to the land.
If this idea is to be accepted, we must secure for it a
higher place in the mind and active effort of many
people. Large numbers of people must become aware
and concerned. They must be informed about why it
is being considered over other alternatives for dispos-
ing of sludge; how it will work; its consequences in
terms of such things as dollar costs, effect on health,
and on agricultural production.
People must feel positive and not negative. They
must feel supportive of the idea, that it is progressive
and not regressive, that it will result in a net gain in
environmental quality, and that it is worth the extra
costs entailed. Feelings of uncertainty and suspicion
must be replaced by reliable factual information and
analysis. Feelings of frustration and hostility must be
replaced by feelings of mutual trust and dedication to
the common goal.
People must be willing to act differently. For this
idea to be adopted, decisions must be made and ac-
tions taken to support it. Clear thinking and warm,
positive feelings are not enough. Those already in
favor of the idea must be willing to work out compro-
mises and publicly supported technical and financial
assistance and retribution for those whose property
rights are damaged, all of which may be necessary to
win acceptance. Local, state, and federal agencies
must cooperate to get the largest public good for the
least social and economic cost. Elected representa-
tives of the people must provide legislation which
both exercises the will of the majority and protects
the rights of the minority. And local leaders of vari-
ous interest groups must be brought together to find
ways to either make this idea work or find a better al-
ternative.
How do we bring about these changes in behavior?
For this analysis, I shall draw upon the works of Dr.
Gordon Lippitt, an outstanding psychologist, and
Dr. Ralph Tyler, nationally recognized educational
theorist and behavioral scientist plus my own experi-
ence and study of public policy education.
207
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208
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Why People Resist Change
First, let's look at Gordon Lippitt's analysis of
why people resist change. In brief, he says that people
resist change under the following conditions:
• When the purpose is not made clear—mystery
and ambiguity cause suspicion and anxiety. If
people can't tell where you'e going, they may be
reluctant to join you for the trip.
• When they are not involved in the planning.
• When an appeal is based on personal reasons
(yours, not theirs).
• When the values, norms, and habits of the people
are ignored.
• When there is fear of failure, i.e., that the goal
may not be reached with the funds available.
• When the cost (social and economic) is too high
in relation to the benefits or when they believe
the costs of an alternative method would be low-
er to secure the same results.
• When the present situation seems satisfactory.
Why upset the applecart?
• When they think they may have to pay the costs
for benefits someone else will receive.
We all know that people with vested interests may
be very hard to sell on this idea. They may not only
be hard to sell but able to block its implementation
almost indefinitely, especially if the public feels that
they are being treated unfairly or unjustly. Take for
example the farmer who may have heard that some-
one is planning to spread city sludge on his farm. He
is not only aware but hostile, fearful, and concerned
about what will happen to his land and his family. If
this farmer's interests aren't considered and he isn't
involved in the planning or if he's treated arrogantly
and unfairly, the public and legislators who represent
him may decide that equitable and just treatment for
him is more important than clean water in a river.
Public opinion usually favors an underdog. Also, he
may know not only Tiis commissioner and councilman
and his State representative and State senator but also
his congressman, his senator, and the governor. A
surprisingly few such people can block a seemingly
good idea for a long time.
Overcoming Resistance to Change
Turning this coin over and looking at it from the
positive view, we have learned a great deal about how
to reduce resistance to change (e.g., to recycling ur-
ban sludge to the land). Some of the principles are as
follows:
• Involve the people in the diagnostic and creative
processes of decision making—they tend to un-
derstand and support what they create.
• Allow the people to blow off steam. Too often
people pushing an idea try to move ahead "so
fast that the opposition won't have a chance to
organize." These famous last words show lack of
appreciation for the principle of "catharsis"—to
relieve emotion so that objective discussion and
deliberation can take place. Don't fear it1 En-
courage it!
• Be certain that people agree upon the goals and
reasons for the change. Clarify the whys and
wherefores.
• Build a trusting climate—tell the truth; main-
tain open communications; don't spring deci-
sions on them; develop mutual respect.
• Provide the information needed for people to
think intelligently. This provides the basis for
people to make sound decisions.
• Provide an opportunity to grow (through greater
knowledge of the environmental quality problem
and what would happen if we were to recycle ur-
ban sludge to the land).
• Provide meaningful rewards—self-expression,
recognition, opportunity to acquire new know-
ledge.
• Keep people informed. They will get more inti-
mately involved if they know the latest details.
A moment's reflection tells us that these are all really
quite common-sense ideas. Our own experiences in
dealing with our friends, our families, the people with
whom we work, and the public lead us to these con-
clusions.
Helping People Acquire New Behaviors
We, who wish people to change their behavior,
cannot get them to do so by saying "You ought to
think, feel, or act differently" unless they hold us in
the highest possible esteem. Neither can we coerce
them into it. What we can do is provide various
stimuli which hook their interests or concerns. Then,
after they become more intellectually or emotionally
involved, they will behave differently; and when vari-
ous segments of the public behave differently—we
hope more positively—-toward recycling urban
sludge to the land, we will have achieved our goal.
Now let's turn to Dr. Tyler. He says that:
• New behavior is acquired only when practiced
and when the person receives satisfaction from
it. This stimulates him to repeat his ways of
thinking, feeling, or acting, and to go further.
Behavior which gives us satisfaction is continu-
ally repeated, while that which is not satisfying is
quickly dropped.
• To acquire new behavior, the person must be in-
volved; must put something into it.
• For carryover of behavior to take place, the per-
son must perceive a connection between what he
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PUBLIC ACCEPTANCE
1201>
is learning and how it affects his own life, e.g.,
provides a safer environment.
• Change is more rapid when people get informa-
tion from a variety of approaches in which they
can see common elements in a variety of situa-
tions.
• Each idea and relationship must be within the
person's ability to perceive at his level of inter-
est, concern, and knowledge.
Dr. Tyler's principles for helping people acquire
new behavior are understandably very similar to
those of Dr. Lippitt. They are as follows:
• Clarify the behavior you seek to develop in the
individuals. Only when we know the behavior we
wish to influence can we plant our information
and educational program effectively. With refer-
ence to recycling sludge to the land, what behav-
ior do we wish to stimulate? Examples are: (])
Do the people lack interest? If so, the behavior
we need to develop is "greater interest." (2) Do
the people need to develop an attitude of con-
cern for public welfare? If so, we need to help
them see the effects of pollution on our rivers
and lakes. (3) Are they familiar with the various
methods of dealing with the problem (urban
sludge in this instance)? If not, our goal should
be to acquaint them with what the choices are.
(4) Do they need greater ability to predict prob-
able consequences of alternative methods of dis-
posal of sludge? If yes, we need to provide them
with the information on what would happen if
we were to implement various alternatives (how
they work, costs involved, benefits, who pays the
costs, who benefits).
• Stimulate the people to react. Let the people
know what is being considered from the earliest
possible moment (via any media). New know-
ledge of this type immediately turns on people's
intellectual curiosity, triggers analysis. In deal-
ing with the public, we are too often fearful of
what people will say so we put off this stimula-
tion and slow down the development of public
opinion. If "catharsis" is needed, it is better to
have it in small doses than in upheavals of pub-
lic opinion.
• Guide the people's reaction, not by telling them
what they ought to do, but by focusing their at-
tention on points they can perceive and helping
them move from point to point until they have
the whole picture. A well-planned program
should help them have the same experiences as
people who think, feel, and act positively to-
wards this idea.
• Provide satisfaction with resulting behavior, e.g.,
provide a forum for leaders to express their
thoughts and feelings or publicize what they
have done.
• Organize the educational program so that the in-
dividual can relate what he is doing in some
other area of his life with recycling of urban
sludge to the land, e.g., for the public—its effect
on food production; for the farmer—its effect on
corn yields. Any important change in behavior
takes time; and the more quickly this integration
take place, the more rapidly will public opinion
be formed.
• Make continuous appraisals of what the public
(various parts of it) is thinking, feeling, and do-
ing concerning this idea. This is done by conver-
sation, observation, and the use of planning
committees.
A Proposed Educational and
Informational Program
On the basis of the problem we face in winning
public support for recycling urban sludge to the land
and the principles of behavioral change outlined
above, let me propose an Educational and Informa-
tional Program. In developing such programs, we
face five fundamental questions.
Whom specifically are we beaming the program to-
ward?
Who are the target audiences? Different segments
of society have different interest levels, differences in
prior knowledge and understanding, different vested
interests, and different concerns. So for greatest ef-
fect, we approach each of them in a different way.
For this program, I identify four major audiences:
(1) The uninterested general public, (2) Decision
makers and others already concerned about the en-
vironment and different ways of handling urban
sludge, (3) People with vested interests, and (4) Pro-
fessionals from government agencies and institutions
who work directly with the people who will be most
affected by this decision.
What behavioral changes do we wish to bring about
in each segment?
• Awareness and interest.
• A decision to believe in an idea.
• Active engagement in support of the idea.
• Involvement in modification and innovation to
put the idea into effect.
Differentiation in interest and knowledge among
various target audiences make it necessary to concen-
trate on behavioral changes appropriate to each. Al-
so, mass methods and media are most effective and
economical for some behavioral changes, while face-
to-face is best for others.
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
What information is needed to capture the attention
and interest of the people in each audience and to
bring about the desired behavioral change?
It takes different information to interest the public-
spirited citizen not directly involved than it does to
interest an irate farmer who has his mind made up
that "They're not going to dump that city sludge on
my land!"
Also, it is important to figure out exactly which in-
formation is needed by the audience concerned so as
not to bore people with something they already know
or waste time and money trying to "teach them more
than they want or need to know to change their be-
havior."
What are the best educational methods for bringing
about the type of change desired?
What is the best means or media of communication
with the target audience?
Now let us summarize the educational program for
each target audience.
1. For the general public:
a. Behavioral changes we seek—greater awareness,
interest, and concern about recycling urban sludge
to the land.
b. Methods—clarify goals. Attach a new interest
(recycling sludge to the land) to an old one (reduc-
ing pollution of the water). The public knows that
people in cities and towns are going to continue to
produce sewage and that it must be disposed of
some way. They also know that it is impossible to
use septic tanks and disposal fields for large con-
centrations of people. They know that sewage goes
into sewers. Beyond that, they don't know
much—nor do they care, unless sewage disposal
becomes a problem—which it has.
c. Means of communication—news releases and
feature stories in mass media (TV, radio, news-
papers, magazines) and speeches.
2. For decision makers and others concerned about the
environment and different ways of handling urban
sludge:
This includes lay leaders, legislators, elected offi-
cials, interest groups, and leaders of various institu-
tions serving the public.
a. Behavioral changes we seek—active support for
recycling sludge to the land.
b. Methods—broaden the base of knowledge and
understanding about ways of handling sludge and
the consequences of each. With this knowledge,
people can make choices based upon their own
value system, which hopefully already includes a
desire for cleaning up the environment. They must
be given comparative knowledge about all the al-
ternatives, among which are:
• Recycling sludge to the land.
• Recycling sludge to the lakes and rivers.
• Other.
• Other.
By far the simplest way to get people to look favor-
ably upon one alternative is to let them compare it
with others so that they can tell which they deem
most desirable. This takes some courage on the
part of professionals and planners—and some faith
in the judgment of the public. But if we don't have
that, we haven't much faith in democracy.
For each alternative, we should also provide an
analysis of such things as:
• Dollar costs in terms of aggregates for a city,
or per capita, or some other meaningful
figure.
• Where the money comes from to pay the
costs.
• Effect on the environment to which the sludge
is being recycled. Include the physical, bio-
logical, human, and economic effects.
• Effect on human health.
• Other.
c. Means of communication—being somewhat dif-
ficult to present, emphasis should be given to face-
to-face contact where possible in lectures, sym-
posia, forums, and seminars. People need oppor-
tunities to discuss this with experts. Carefully pre-
pared pamphlets, leaflets, feature stories are excel-
lent supplements.
3. For people with vested interests:
This includes legislators who must prepare legisla-
tion, public officials whose duty it is to make deci-
sions, and citizens who will be significantly affected.
a. Behavioral changes we seek—favorable action,
reduced criticism.
b. Methods—include them in the formulation of
decisions, working out compromises, finding better
alternatives, and compensating those hurt by the
decision. Even though most of this group of people
has a vested interest to protect, they also know
enough to realize that sludge must be disposed of
some way and that ways must be found to keep the
environment clean.
c. Means of communication—personal contact, in-
dividually or in small groups, through which
thoughtful discussion can take place works best.
Means include (in order of effectiveness):
• Inclusion in decision-making groups.
• Advisory committees.
• Public hearings.
It should be recognized that many of these people
have a positive attitude, excellent minds, and great
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PUBLIC ACCEPTANCE
211
knowledge with which to supplement the brain-
power of the professionals. They are in some ways
a free resource.
4. For the professionals from federal, state, and local
government agencies and institutions who work closely
and directly with the people affected by the decision:
a. Behavioral changes we seek—greater knowledge,
favorable attitudes, active support.
b. Methods—involvement. They know a great deal
about the people on whom the decision will im-
pinge and have a great deal of information at their
fingertips to contribute to the educational proc-
esses necessary to win public support. And they
have a desire to help.
c. Means of communication—personal contact,
seminars in which all "agencies" are included.
CONCLUSION
I believe a great deal can be accomplished with an
educational and informational program to win public
acceptance of recycling urban sewage and sludge to
the land. In order to use limited resources efficiently,
such programs should be carefully thought through
and analyzed. Necessary information should be de-
veloped and disseminated as quickly as possible. We
should remember that the changing of public opinion
takes time. For the people to acquire information and
change their ways of .thinking, feeling, and action is a
slow process. Remember—Leadership consists of get-
ting people to do what you want them to do because
they want to do it!
REFERENCES
1. Lippitt, Gordon L., "Overcoming Human Re-
sistance to Change," Selected Perspectives for Com-
munity Resource Development, (North Carolina State
University, Raleigh, North Carolina)
2. Public Allaire Munition, A Report of the Co-
operative Extension Service Committee on Policy,
(Extension Service, U.S. Department of Agnculture,
Washington, D.C., 1969).
3. Tyler, Ralph W., "How Do People Learn," In-
creasing Understanding of Public Problems and Pol-
icies, (Farm Foundation, Chicago, Illinois, 1953).
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Some Extension
Service
Capabilities
CHARLES P. ELLINGTON
University of Georgia
I appreciate the opportunity to take part in this
conference and to expound on some of the strengths
and some of the limitations of the Cooperative Exten-
sion Service.
The Cooperative Extension Service is almost 60
years old. We were created by an Act of Congress in
1914 and given the responsibility to take the findings
of research from the Agricultural Experiment Sta-
tions and to extend those findings to farmers and
others who could put them into use. We have been
known primarily for our work in agriculture and sec-
ondary for 4-H and home economics. Our role in
community development is new to us, and nation-
wide we now expend about five percent of our total
resources in this area.
There is a Director of Cooperative Extension at
each of the Land Grant Universities. There is also an
office in virtually every county in the United States.
Each state has a staff of specialists who provide the
back-up on technical subject matter to the county
agents. Among the specialists you will find Agrono-
mists, Poultry Scientists, Nutritionists, Economists,
Horticulturalists and others. You will also find
specialists in industrial development, manpower,
recreation and several other disciplines. We also have
the capability, in most states, of calling upon experts
from other areas of our state universities—for exam-
ple, in business administration, law, pharmacy, social
services and others as needed.
As you would expect, we have learned a few things
in our 60 years of experience. One of these is to
stimulate interest and to provide information but to
leave the decision making to local people. This is a
cumbersome, slow, and on the surface at least, an in-
efficient way to conduct an educational program. But
it works and it has allowed the Extension Service to
gain credibility in most communities that is seldom
found in the programs of any other agency of State,
Federal and local government.
Extension is frequently asked to "legitimize" or
"sell" a program for one agency or another or as Dr
Dunbar addressed the topic "gain public accep-
tance". I can't speak for all Directors of Extension
but I can speak for myself and my experience has
been rather sad in those instances where we under-
took the job of doing someone else's educational or
informational program.
In the first place, to most agencies the term "edu-
cation" really means information or selling and not
really education at all. Extension education to me
means discussing all the possibilities—all the pros
and all the cons and then allowing people to decide
for themselves. This means that we can stimulate in-
terest and we can provide information but we should
not become the advocates of any agency or of the
programs of any agency.
In the second place, we are in effect trying to
"close the gate after the horse is out". People should
be involved and informed before decisions are made
and not after someone in authority has already de-
cided what should be done and how it should be
carried out.
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214
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
But here are some things we can do:
1. Through the county offices and the county rural
development committees, Extension can locate and
identify the leadership in each county. It is this local
leadership that must be stimulated, informed, and
mobilized in order to gain local support and action.
Extension is in a better position to accomplish this
than anyone else that I know.
2. Extension can provide resources to help deliver
information to the leadership which has been brought
together.
Remember the original charge given to us in 1914
was to disseminate information—not necessarily to
originate it (although in some cases this has been
necessary) but most often to "translate" and pass on
research findings in a usable, understandable form.
In most states, we will not have all the expertise
needed to disseminate information regarding sludge
disposal. But we do possess the ability to either work
with other agencies or to acquire the needed man-
power ourselves to complete the task. Most states will
already have the soil scientists, the engineers and the
economists—but may need to bring in the microbio-
logists, the systems analysts and others to complete
the task.
The machinery or hardware for dissemination of
the information already exists and with but slight
modifications can be put to immediate use.
3. Extension can play the role of the coordinator
or facilitator—we can call the meetings, we can ar-
range the programs, we can help to coordinate infor-
mation from various sources and in so doing provide
the stimulus needed for local citizens to become in-
volved.
We welcome the opportunity to work with you on
the subject of recycling municipal sludges and dilu-
ents—and in fact on any subject dealing with en-
vironmental quality—on a continuing basis
-------
Informal
Opinions
CHARLES JELINEK
United States Department of Health,
Education and Welfare
(An unscheduled report was given by Charles
Jelinek, HEW Food and Drug Administration, Wash-
ington, D. C. His report was transcribed as follows.)
Rufus Chancy asked me earlier today if I would be
willing to just give you my own informal opinions on
FDA's outlook towards the use of sludge or effluents
as fertilizer for either food or feed crops, so this is it.
This is no official viewpoint at all because we don't
have one. Our charter, in the Bureau of Foods within
FDA, is to make sure the food that all of us eat, you
and I and our kids and our grandchildren, don't pre-
sent any unnecessary or unusual hazards to health.
So, as an extension to that, we are interested in the
use of sludge or effluents as fertilizers. We want to
make sure that such use doesn't furnish any undue
hazards in our food supply. I would say the main
contaminents that we are interested in are the
chemical contaminents, mainly the heavy metals but
also organic chemicals. And then also the pathogenic
organisms. One thing I want to stress right off the bat
and that is that we are not out to stop the use of
sludge or effluents as fertilizers for crops. We are
interested in looking ahead to see or try to foresee
what hazards there may be in foods. This is so that we
can stop it right at the root cause before there is some
full-blown crisis that is going to develop from some
food that is being grown in some producing opera-
tion. When that happens you have seizures and re-
calls, and believe me that is no fun for us and it is no
fun for the people who are producing the food in-
volved.
In regards to chemicals and heavy metals, the ones
that are of main interest to us at this time in regards
to contamination in foods are mercury, lead, cad-
mium, arsenic, selenium and zinc. Organic chemicals
right now, mainly pesticides, PCB's are products of
that type.
I would like to tell you a little bit about a couple of
problems that are causing this concern now, because
I think it gives you good background on our interests
and our concern in regards to the use of sewage and
effluents as fertilizers. In regards to cadmium, I
would say right now neither we nor anyone else has
really settled on a good estimate of what the accep-
table daily intake is, and I might say that any time
you see a figure of acceptable daily intake, that is
nothing that is engraved in stone. It is a hell of an
educated guess and that is about the best that you can
ever do. But, anyway, based on oh, present estimates,
primarily from Swedish workers, is that maybe two
hundred micrograms per day of cadmium. There is a
minimum amount that is going to cause damage to
kidneys and I want to say right off the bat that we
don't accept that as gospel, but right now it is about
the best level to at least be used to guide our thinking.
And probably in the diet, the average diet that an
American adult eats, he is getting between 50 and 100
micrograms per day. So you can see we don't have
very much of a safety margin. That is a two fold to a
four fold safety margin. When you are talking about
toxicology, that's really skating on thin ice. We are
carrying out additional toxicological research on our
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216
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
own to try to arrive at some figure that we will have
more confidence in or where there will be more back-
ground. But anyway, right now I would say our think-
ing and that of people in other countries and in a
similar type of job is that there just isn't any room in
the diet to have additional increases of cadmium
coming along.
Now, in regards to lead, I can tell you one of the
things we are faced with, and again this is just sort of
an estimate, that for three to six year olds the
maximum intake for lead per day that would be per-
missible, is around three hundred micrograms per
day from all sources. Not only from foods but from
eating paint and breathing in automobile exhaust and
so on and so forth. From data that we have and other
people have in regards to the diets for small kids and
infants, I can see that again we don't have much room
for safety. And this is a problem that we are wrestling
with right now. Again, I would say that anything that
is going to lead to an increase of lead in the diet, and
especially a diet that would be important for small
children, is something that we just feel ought to be
avoided at all costs.
I sort of feel like a temperance lecturer up here
right now because I am exerting all of you and I
really don't have any really good hard guidelines to
give you. The only guideline we have on heavy metals
is an action level of half a part per million mercury in
fish. That one—our job of setting a guideline there
was simplified by the fact that essentially all of the
mercury that we get in our diet comes from fish.
Milk, bread, meat, everything else, eggs, practically
no mercury, so the problem is simplified. But when
you get into things like cadmium or lead or arsenic or
selenium, these occur in a lot of different types of
foods. That complicates it. Also as we all know they
are naturally occurring materials. So, some of the in-
formation that we have to develop before we can set
any sort of action levels or alert levels or guidelines
that are really soundly based require that first of all
we do have to develop more toxicological informa-
tion to give us a better idea just what the acceptable
daily intake could be. Then, on the other side of the
fence, we have to develop more information in
regards to the level of occurrence of these various
contaminents in foods for several reasons. One is to
get a good idea just what the background level is. We
would really look like a bunch of damn fools if we set
up some action level for some contaminent and it tur-
ned out that the average natural occurrence level was
higher than that.
The other is to get a good idea as to what the total
intake is from all of our diet and also what the con-
tribution of the levels of the given contaminent is ris-
ing from different food items. So, these are things that
we have to do and right now some of our activities
along these lines, in addition to the toxicological in-
vestigations, we are measuring levels of all six of
these heavy metals I mentioned in the total or our so-
called total diets survey which represents the average
diet of the American adult and this is based on USPA
information that they developed some years ago. At
the same time we are developing similar information
on pesticides. Also this fiscal year we are going to be
determining the levels of these same six metals in fish.
In lead, cadmium and zinc we are going to carry out
a big survey on these three metals in 40 different food
items, 20 canned and 20 non-canned. Among the non-
canned items, just in the meat items I just might men-
tion those, chicken, bacon, beef muscle, I forget
whether that is chuck or roast or what, beef liver,
hamburger and frankfurters. Also leafy vegetables
such as lettuce and so on and so forth.
So, we hope at the end of this fiscal year we will
have a lot better idea just what the level of these
metals of concern to us are, not only in the overall
total diet but in the major food items themselves.
Based on that and additional toxicological informa-
tion that we develop, then we finally will set some
sort of action levels. But that is not going to be for
any of these metals, just one level, say X parts per
million of lead and for every item in food. I don't
think we will have one single overall level. It will be
different for different types of food.
Well, then, where does this lead us right now—in
the types of operations we are talking about here
where you are considering major new projects for
using sludge or effluents as a fertilizer for either food
crops or animal feed crops? We feel that in projects
of this type you should carry out monitoring opera-
tions. More specifically ones where from the stand-
point of testing you would grow the crops that you
are interested in on test plots. At the same time con-
trol tests must be run with the same kind of crops
and the same land using a commercial fertilizer and
analyzed for these heavy metals I mentioned, also
pesticides and also for pathogenic organisms. In the
case of the metals and organic contaminents, if there
is any increase, significant increase in levels, in the
metals or organic materials, in the ones fertilized with
sludge as compared to those fertilized with commer-
cial fertilizers, I think that you ought to look at that
very seriously and probably consider growing some
other crop on it. That is about the only suggestion I
can make at the present time. I wanted to have the
chance to talk today because I know that a lot of this
is controversial to a lot of you people, but I wanted
you to have the chance to think about it so that when
we get into our workshop discussions on Thursday, at
least you can have your own thoughts gathered
together along these lines.
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FDA'S OUTLOOK
217
Incidentally, you will notice I haven't said too
much about pathogenic microorganisms and the main
reason is that I am not a microbiologist myself and in
this case I am just sort of speaking the views of other
people in the Bureau of Foods, but they are very
seriously concerned too that if these operations aren't
monitored in the early planning stages to make sure
we are not introducing pathogens into foods, that we
could also run into trouble.
DISCUSSION
QUESTION: Al Page, University of California.
Our last speaker mentioned a level in foods for lead
of 300 micrograms per day per children, three to six
year olds, I was wondering if he had a level for
adults?
ANSWER: A figure of around 400 to 500 micro-
grams per day.
QUESTION: William Bauer, Bauer Engineers,
Chicago, Illinois. Suppose that in comparing the
crops grown on the sludge enriched soils or the crops
grown on non-sludge enriched soils that you found
the addition of sludge reduced the lead content for
those particular crops, but let's say it went up for
cadmium. What would be the view of the FDA on a
case like that?
ANSWER: I would say we would say don't grow it
because you have to consider each of these con-
taminents as an entity in itself. On the other hand,
if use of sludge reduced the level of all of these con-
taminents as compared to a commercial fertilizer I
would say that is all to the good. That would be fine.
But ultimately when we set levels then that is what
the level is going to be for the given food regardless
of what is used as a fertilizer or whether the metal
came from the tin can or from the meat grinder.
When we find that level, well then that material gets
seized or gets re-called from the market or something
like that. So, all we are trying to do here is for all of
us to look ahead and plan ahead if it looks as if there
is some high level then, of course, for that particular
metal the best thing is to try to cut it off at the source.
If you have some industrial installation that is dump-
ing its effluent in there that is high in this particular
contaminent, may be you can remove it right at the
source.
COMMENT: Rufus Chancy, USDA. One com-
ment that I was unable to get in this morning and I
think really needs to be made, is that there are some
real benefits from these micronutrients in excess we
find in sludges. The zinc and copper are frequently
marginly sufficient or actually deficient in soils and
the sludge, zinc and copper can be of meaningful
benefit for putting sludge on land along with the
other benefits that we see. The fact that many human
diets, particularly some special groups, are zinc
deficient already, (clinical zinc deficiency in big
cities and teenage groups) shows that if we do any-
thing with sludge to improve the zinc content of
crops, it is a very meaningful benefit. So, I was hitting
out again some things this morning, I want to let you
know there are some real benefits and we aren't say-
ing keep it off all together, we are saying spread it
out.
CHAIRMAN: That is very simple. I wish we knew
the answer.
-------
Workshop Session Reports
The Research Needs Workshop was designed to achieve the objectives of iden-
tifying what is known about municipal wastewater effluent and sludge application to
the land and what research is needed for successful application of such wastes to the
land from economic, engineering, health, and esthetic points of view. The following
ten Workshop Sessions were designed to achieve the latter objective:
1. Educational and Informational Needs
2. Public Health Aspects
3. Dimensions of the Problem
4. Land Resource—Sludge
5. Land Resource—Effluents
6. Plant Characteristics and Response—Soil-Nutrient
Relationships, Crop Selection and Management
7. Plant Characteristics and Response—Toxic Chemicals
8. Options, Problems, and Economics—Engineering Systems
9. Options, Problems, and Economics—Agricultural Management
10. Political and Institutional Constraints
The participants of each workshop group were selected to represent a multi-
discipline and multi-organizational approach to the task of identifying research
needs. The individual results of each of the ten Workshop Sessions, including the list
of participants, follow.
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220
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
WORKSHOP GROUP 1
Educational and Informational Needs
Many of the papers and much of the discussion
emphasized the importance of public acceptance if a
project is to succeed. Consequently, public affairs
education is an essential part of any program concer-
ned with the recycling of sludge and/ or effluent on
land.
Our work group feels that the majority of the citi-
zens should understand certain basic concepts of
waste management if a successful educational pro-
gram on recycling municipal wastewater on land is to
be successful. They are:
1. The production of waste is a natural process.
2. Wastes are a part of a natural cycle; they contain
organic matter, plant nutrient and other ma-
terials.
3. Wastes may be a valuable resource in the future
to meet our growing needs.
Our educational researchers have explained how
farmers accept new ideas and adopt new technology;
perhaps the same processes apply to the wastewater
recycling projects.
The acceptance of new ideas resulting in the appli-
cation of new technology utilizes two interrelated
processes—diffusion and adoption.
Diffusion refers to the spread of new ideas from the
originating source to the ultimate users.
Adoption is a mental process through which an in-
dividual undergoes from first hearing about a new
idea to accepting it and acting upon it. The diffu-
sion/adoption process may be subdivided into five
stages. They are:
1. Awareness. The individual learns about a new
idea but lacks sufficient information about it.
2. Interest-Information. The person becomes inter-
ested in the new idea and seeks more information
about it.
3. Evaluation-Application-Decision. The individual
mentally applies the new idea to his present and
anticipated future situation and makes a decision
either to try or reject it.
4. Trial. The individual applies the new practice on
a small scale to validate its workability in his
situation.
5. Adoption. The individual applies the new prac-
tice on a full scale and incorporates it into his
management system.
At any point in the diffusion/ adoption process an
idea may be rejected. Even after adoption of an idea,
the practice may be replaced when another alterna-
tive is presented.
A major difference between the diffusion process
and adoption process is that the diffusion occurs bet-
ween persons and institutions while the adoption
process is an individual matter.
Traditionally, Extension Service programs have
dealt primarily with problems or issues in which in-
dividuals or a homogeneous group made the decisions
and had the power to carry them out.
However, municipal wastewater is what we are
concerned with at this workshop, and it requires
group or multi-group action who may or may not
have a common interest.
We must recognize that regional-urban wastewater
and sludge management programs such as the
Chicago-South End of Lake Michigan, Cleveland-
Akron, Detroit, etc., requires cooperation between
many governmental (Federal, State and local) en-
tities, agencies and special interest groups—particu-
larly local communities and farm groups far removed
from the wastewater source.
Perhaps our prime educational research need is the
development of techniques, methods and procedures
for handling controversial issues between such di-
verse groups so the results can be better predicted.
Such an approach as Robert J. Burns, Extension
Service, University of Missouri, has been using in
conducting educational programs involving contro-
versial issues called "Defusing" Public Decision
might be adopted to urban wastewater land treatment
programs.
The Sevens approach lists five steps:
1. Define the problem. The problem must be de-
fined with sufficient generality to avoid argu-
ment over what is the problem. One way of
avoiding this is to never define the problem in
terms of a solution to the problem.
2. List goals and values.
3. Develop alternative solutions. Perhaps three to
five.
4. Explore the consequences of each alternative.
5. Leave the decision to the people.
One of the keys to the success of the Sevens ap-
proach is early involvement of the various groups
from the beginning.
As an example of the many groups that should be
involved in an educational program, based on a pro-
posed wastewater management study to be conducted
by the Corps of Engineers for example, the Atlanta
area, see the figure below.
1. The basic principle illustrated by Figure 1 is to
involve opinion makers and interested people as
soon as the study is authorized (pre-planning),
meet with leaders, and keep the general public
informed through the news media.
2. In developing the educational program let the
leaders make the local leaders want to be a part
of the decision-making process. Our society
guarantees them this right.
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WORKSHOPS
221
MAYOR
EDITOR
CHAMBER
OF
COMMERCE
UNIV
OF
GEORGIA
UNIV. OF GA.
EDUCATIONAL
PROGRAM
CORPS OF ENGINEERS
CHAMBER
OF
COMMERCE
FARM ORGAN
SCHOOLS
ECOLOGY GROUPS
EPA
CITY GOVTS
COUNTY GOVTS.
OTHER
UNIV.
PRESS
Figure 1: Developing an Educational Program Requires the Involvement of All Major Interested Groups.
In order to develop an educational program on re-
cycling municipal wastewater on land, materials need
to be developed on all phases of the problem—writ-
ten material, slide sets, movies, etc.
Most people do not know that the two major com-
ponents of wastewater is effluent and sludge—start
here. An educational program of any value must start
at the land of the level of the understanding of the
people.
Materials should be developed which will explain
the Federal Water Pollution Control Act Amend-
ments of 1972, what they mean and their implica-
tions. These materials should include the goals and a
schedule for attaining the goals.
Demonstrations should be developed which will
have general application and they should come after
the local leaders have generally agreed that an edu-
cational program has been developed that will work.
The purpose of demonstrations is to show results.
The work group was favorably impressed with the
land reclamation project which uses Chicago sludge
in Fulton County. However, they offer the following
suggestions which might be considered in similar
projects.
1. Develop an attractive information center. Use
slide sets or movies to explain the problem, the
goals, and how they are to be attained. Also pro-
vide some kind of handout—a brochure which
summarizes the project.
2. Demonstration area—keep it up to date, attrac-
tive, and readily accessable for observation.
3. The projects could perhaps encourage local lay
groups to develop demonstrations to comple-
ment the project. For example, garden clubs
might be involved in developing some plots on
which flowers would be grown utilizing sludge.
Perhaps these flowers could be used by them in
their functions.
4. Provide a photo display of some of the bass
caught from the lakes, wildlife, and ponds of the
area and other recreation and camping attrac-
tions.
The selection of agricultural crops requires the ex-
pertise of many resource people from various agen-
cies—Forest Service, SCS, Extension Services and the
Colleges of Agriculture. These agencies' staffs con-
tain many disciplines which are essential if the proj-
ect is to be effective and if the public is to obtain a
good understanding of the project. The project
should not be confined to technical people, but
should also involve public relations, recreational,
and other groups who can contribute to the total edu-
cational effort and acceptance by the public.
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222
RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
Participants
E. S. Carbertt, N.J. Forest Experiment Station
R. Ford, Extension Service, USDA, Chairman
J. E. Halpin, South Carolina
R. D. Walker, University of Illinois, Secretary
R. G. Yeck, Agricultural Research Service, USDA
WORKSHOP GROUP 2
Public Health Aspects
Research needs on the public health aspects of the
use of sludge or effluent on land were considered by
our workshop to be dependent upon the point of view
regarding the seriousness of pathogens in the waste.
One point of view was that since viruses and other
pathogens regularly occur in sewage wastes, these
wastes should not be distributed in the environment
unless disinfected by pasteurization or equivalent
treatment. Basic technology for achieving this patho-
gen decontamination exists, but research is needed to
provide precise information on dosages of heat or
chemicals for dependable and economical kill of
pathogens in sewage sludges of all types. Detection
methods need to be developed for detection of very
small numbers of pathogens, especially viruses, in
sewage sludges and effluents to assure effectiveness of
pasteurization. For sludges, heat pasteurization is
more feasible than chemical decontamination but re-
search is needed to improve methods of measuring
temperatures inside sludge particles where viruses
may be protected. Methodology needs to be devel-
oped for improving chemical treatment of effluents
supported by techniques for detecting low levels of
pathogens in large volume of effluents. Methods must
be developed for measuring a disinfecting chemical
species in effluent systems being treated to be assured
of adequate levels of the active agent. Improved tech-
niques for measuring pathogens in soil and in aerosols
are also needed to monitor disinfection practices.
The other point of view is that land disposal of
treated sewage wastes has not so far been shown to be
a greater health hazard than conventional disposal
systems. Pathogens are known to survive the conven-
tional treatments (e.g., secondary activated digestion,
anaerobic digestion, liming), but their threat to pub-
lic health may not be great enough to require disin-
fection by pasteurization or chemical means. At least
there is insufficient data to show whether or not this
is necessary. In this case research needs can be listed
as follows:
1. The first priority research need is for compre-
hensive epidemiologic studies on human popula-
tions associated with both new and long-estab-
lished land disposal systems. This would be
studies on sewage plant workers and their im-
mediate families. The objective of these studies
should be to provide sufficient reliable data on
health hazards of land disposal alternatives so
that Federal, state and local health agencies can
have a rational basis for uniform regulation and
permits.
2. The second priority need, with either alternative,
is better monitoring capabilities. There is need
for improved methods of detection of both bio-
logic and chemical pathogenic agents and for
standardization of testing protocols.
3. An expansion of research is needed on disper-
sion of pathogens, especially viruses in aerosols,
whether produced by spray irrigation of effluent
on land or by various treatment practices in sew-
age treatment plants.
4. More basic research is needed on survival of en-
teric pathogens (viruses, bacteria and parasites)
in soil, water, air when sludge or effluent is used.
Movement of pathogenic agents through soil al-
so requires more detailed study.
5. Since sludges and effluents may be applied to
forages and pastures, more research is needed to
determine health effects on livestock or on
humans consuming livestock products from such
treated fields.
6. There is general agreement that sludges and ef-
fluents should not be applied directly on human
food crops and arbitrary waiting periods are
usually imposed on sewage treated land before it
is used for producing human food. Information
should be obtained to provide a more accurate
basis for establishing the length of this period be-
fore food crop production can be allowed.
7. We are concerned that expenditures for demon-
stration and construction of sewage treatment
and disposal systems are not adequately suppor-
ted by research components. It is recommended
that grants for these projects include an adequate
proportion of funds for research and monitoring.
8. Finally, it is recognized that there are also posi-
tive health effects on the nutritive value of crops
produced on sludge and effluent treated lands.
These beneficial features need to be fully con-
sidered in arriving at benefit-risk ratios for dis-
posal systems.
Participants
George D. Ward, George D. Ward and Associates
Charles F. Jelinek, HEW-Food and Drug
Administration
Robert K. Bastian, EPA-Region V
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WORKSHOPS
22M
Paul A. Blakeslee, Michigan Department of Natural
Resources
Edward F. Baer, FDA, Div. of Microbiology
Ivan C. Smith, Midwest Research Institute
Francis E. Broadbent, University of California
Wylie D. Burge, USDA-Biological Waste Manage-
ment Laboratory
Thomas L. Gleason, III, EPA
Mirdza L. Peterson, Metropolitan Sanitary District of
Greater Chicago
Gerald Berg, EPA-NERC
H. G. Geyer, USDA-Extension Service
J. D. Menzies, USDA-ARS, Biological Waste Man-
agement Laboratory
WORKSHOP GROUP 3
Dimensions of the Problem of
Recycling Municipal Sludges
and Effluents on Land
Statements of Fact/Observations
1. The 1972 Act recognizes that the treatment of
sewage or sludge on the land is an acceptable
form of treatment for municipal sewered wastes
which must be considered as an alternative for
Federally funded grants and the cost of the land
used for treatment is eligible for grant reim-
bursement. Emphasis in the future should be on
wastewater utilization and renovation and not on
disposal. This is sometimes called the "4-R
Cycle"—Return of wastewater to the local land;
renovation of wastewater by soil and plant ac-
tions; recharge of groundwater resources; reuse
of wastewater.
2. The volumes to be handled and the physical
characteristics of sludges and effluents are suffi-
ciently different to require separate recom-
mendations and guidelines in many cases.
3. Parameters controlling use of the land depend
upon local conditions including soil types,
drainage, groundwater geology, climate, type of
sludge and other local constraints.
4. Public acceptability is the primary factor limit-
ing land treatment of effluents or land utilization
of sludges.
5. Nearly all soils can accept some sludge and
where land utilization of sludge has public ac-
ceptance today the costs are significantly lower
than other alternatives. The process thus satisfies
the cost effectiveness criteria required by law.
6. A large fraction of the population has land suit-
able for a sludge utilization within a reasonable
and feasible distance.
7. The segment of the population which can be
served by sludge utilization on the land is the
segment which has access to regions which can
be persuaded that sludge utilization on the land
is acceptable.
8. Land application of wastewater is not an alterna-
tive to secondary treatment if secondary treat-
ment is required as a pretreatment.
9. Land application of wastewater is an alternative
to tertiary treatment for the removal of nutri-
ents, suspended solids and some other pollutants.
(It is not effective for the removal of soluble
salts.)
10. The segment of the population that can he
served by land application of wastewater is sub-
stantially less than the segment that can benefit
from land utilization of sludge because on mos
soils at least ten times as much land will he re-
quired for effluent irrigation as would he
required for sludge.
11. In water-short areas land treatment of effluents
may be considered as part of the reuse cycle
12. Small communities will probably continue to be
the principle users of land treatment of effluents
for the near future but stringent discharge re-
quirements will make land treatment more at-
tractive to large communities.
13. Research projects at Universities in recent years
are influenced primarily by the sources of out-
side funds. There is a tendency for research on
cause and effects to be superceded by demon-
strations of processes.
14. Research and development priorities in EPA,
USDA, and other government agencies are de-
cided centrally based on needs statements sup-
plied at least in part by the various regional of-
fices.
15. Work is done by
(a) in-house scientists and engineers,
(b) contracts,
(c) grants and,
(d) cooperative agreements between agencies
and/or universities.
16. Significant cooperation exists between in-
dividuals at the operating level, whether or not
there are formal cooperative agreements be-
tween their respective agencies.
RECOMMENDATIONS
1. Limitations and restrictions on land utilization
or treatment of sludges or effluents should be
comparable with restrictions set on other per-
mitted forms of discharge.
2. An immediate epidemiologic study of selected
existing land utilization and treatment sites
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
should be carried out with appropriate controls
to evaluate the magnitude of the health problem
in comparison with other methods of treating
sludges and effluents.
3. Research should be carried out on the historical
and long term effects that can be measured at
existing facilities which have been using effluent
application or sludge disposal on the land for
many years while recognizing that these existing
facilities were not designed primarily for waste-
water treatment or for research on land utiliza-
tion.
4. Research should be directed toward assessment
and prediction of groundwater quality resulting
from land treatment of effluents or sludges.
5. Guidelines should be set on an areawide basis
considering land capability and other local con-
straints.
6. Research on markets for effluents and sludges is
needed.
7. Finally it is recommended that an inter-disci-
plinary committee meet periodically and publish
task force reports on current research results of
land treatment and utilization along the lines of
the Workshop conference for Recycling Munici-
pal Effluents and Sludges on Land, held July 9 -
13, 1973 at the University of Illinois.
Participants
S. Reed, U.S. Army Cold Regions Research & Engi-
neering Laboratory
B. W. Post. USDA-CSRS
Charles Pound. Metcalf & Eddy, Inc.
A. Joel Kaplovsky, Rutgers University
Curtis C. Harlin, EPA, Robert S. Kerr Environment-
al Laboratory
T. D. Hinesly. Office of the Undersecretary of the
Army
Robert B. Dean, EPA-NERC
L-au rence Heffner. USDA-Hxtension Service
Paul Leva, EPA
B L. Seabrook, EPA-Office of Water Operations
John C. Frey, Penn State University
R. G. Forscht, USDA-ERS
A. R. Tiedmann, USDA-Forest Service
Lewis Porteous, EPA-Region IX
WORKSHOP GROUP 4
Land Resources—Sludge
The objective of the workgroup was to develop a
list of land resource related research needs to enable
engineers to design feasible land spreading systems
for municipal sewage effluents and sludges.
There is a considerable accumulation of informa-
tion from research and experience that is useful. A
great amount is known about the nature, location,
and extent of soils and crops. Most soils are capable
of assimilating sludges at a reasonable application
rate with improvement in physical, chemical and bio-
logical properties resulting. Sufficient information is
already available to design, with reasonable confi-
dence, a land spreading system for small communities
where light annual applications are made.
The following studies and activities arc needed to
plan and design land disposal systems in accordance
with the characteristics of the land
1) Nitrogen transformations with particular em
phasis on development of techniques for controlling
nitrogen leaching and pollution of groundwater.
2) Effects of various kinds of sludges on specific
combinations of soils, crops and climates: (A) Long-
term effects of heavy metal and organic matter addi-
tions; (B) Effects of applying advanced waste treat-
ment sludges, physical-chemical sludges, and others
to various soils, (C) Select standard crops, soil para-
meters and methods lor determining parameters to
facilitate comparing systems and evaluating their ef-
fectiveness; (D) Develop soil management technology
to control metals in soils.
3) The effect of soil properties, climate, and land
use upon fate of pathogens and parasites applied in
sludge.
4) Crop selection and development of practices for
optimum land management and waste renovation.
5) Study a minimum of twelve soil-climate-crop
combinations to establish benchmarks from which
guidelines can be developed for all soils and loca-
tions in the country.
6) Improve technology of renovating unproductive
soils with sludge.
7) The effects of adding sludge borne salts in rela-
tion to soils and climate.
8) Establish technical assistance teams to help
communities evaluate and establish sludge spreading
as a disposal method.
9) Determine the soil and geologic factors that in-
fluence the rate of movement of leachatcs through
soils, and the rate of diffusion and dilution in ground-
water.
10) The feasibility of combined sludge and effluent
spreading as related to soil and climatic factors
(Example—follow sludge spraying with effluent in
semi-arid areas to rinse sludge from foliage. Hush ir-
rigation equipment, and leach salts from soil).
11) Develop complementary field treatment
schemes such as small nitrification basins to be used
with storage lagoons to achieve denitrification.
12) Compile a report of the amount of land within
200 miles of major metropolitan areas that is suitable
for sludge spreading.
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WORKSHOPS
225
13) Toxic gas production as related to soil proper-
ties and application rates.
14) We need a measure of persistant salts in sludge.
Most of the conductivity is caused by ammonium bi-
carbonate and organic acids which will be lost. Per-
haps we should ask then extract with boiling water.
Participants
Eliot Epstein, USDA-ARS
T. M. McCalla, USDA-ARS University of Nebraska
B. L. Carlile, North Carolina State University
V. V. Volk, Oregon State University
L. E. Sommers, Purdue University
W. E. Larson, USDA-ARS, University of Minnesota
Benny F. Swafford, U.S. Army Corps of Engineers
Klaus W. Flach, USDA-Soil Conservation Service
Robert H. Miller, Ohio State University
G. Kenneth Dotson, EPA-NERC
WORKSHOP GROUP 5
I^and Resources—Effluents
INTRODUCTION
The charge to the workgroup was to define land
resource problems needing solution for applying ef-
fluents to the land. Addressing this problem stimu-
lated some recommendations of a general nature and
some statements regarding topics which do not ap-
pear to be problems needing research.
The general recommendations are (1) common ter-
minology and definitions should be established to re-
duce confusion, (2) an indicator technique for confi-
dently establishing the presence or absence of harm-
ful viruses would be a great aid to system evaluation,
and (3) establishment of regional research sites
should be considered as a method of developing de-
signs for key climatic, soil, and vegetation conditions.
Topics which do not appear to need research in the
general context of the land resource are the amount
of land required or the availability of land which is
suitable. Problems relating to these topics do exist
but they fall within the scope of other workgroups.
The workgroup considered the land resource prob-
lems needing research separately for low rate sys-
tems—such as irrigation, high rate systems—such as
recharge, and overland flow systems—such as spray -
runoff. Similar research needs are common to each
of the approaches but the relative importance varies
between the approaches.
Two major research needs were identified for the
low rate systems; these are (1) establishment of re-
gional research or demonstration sites to determine
design criteria for various soils, climatic, and vegeta-
tion conditions, and (2) the degree of pretreatment re
quired to protect the public health and assure safe
consumption of crops. (Sec addendum for further
detail.)
The workgroup agreed that high rate systems re
quire permeable soils, low suspended solids in the el
fluent to be applied, and prevention of runoff from
the site. Research needs were listed for the following
areas: (1) combinations of pretreatment, system man-
agement, and vegetative cover that promote nitrogen
removal by denitrification; (2) the influence of cli-
matic conditions on system operation, and (3) the in-
fluence of system aging on hydraulic efficiency and
renovation efficiency. (See addendum for further
detail.)
Overland flow for treatment of municipal waste-
water is a relatively untested approach 1-or u.is rea-
son it has many areas needing research. These areas
are (1) the limitation of soil texture, terrain and cli-
matic influences on site utilization; (2) the effects of
pretreatment (wastewater), site preparation and site
management on system performance, and (3) limita-
tion imposed by aesthetic factors such as public ac-
ceptance or vector nuisances (See addendum lor lur
ther detail.)
The workgroup also feels that more approaches to
land application will be developed and that combina-
tion systems will play a role in practical use situa-
tions. Research needs for such approaches would be
similar to those already detailed for the above
approaches.
Research Needs for Low Rate Systems
I. Degree of wastewater pretreatment necessary:
A. To protect public health.
B. To assure safe consumption of crop by ani-
mals and/ or humans.
II. Establishment of regional research demonstration
sites to determine design criteria tor various soils,
climate and vegetation conditions
A. Soils
1. Evaluation of physical and chemical prop-
erties of soils in relation to their suita-
bility for wastewater disposal.
a. Utilization of these data for model studies
to predict durability of the system
b. Utilization of these data for extension
of the results from the research demon-
stration site for the design of full-scale
operations within the region.
2. Determination of wastewater loading rates
for the region.
B. Climatic Conditions
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
1. Evaluation of the effect of climatic condi-
tions (mean and ranges) on the operation
(annual or seasonal) of the system.
C. Vegetation
1. Development of suitable crop management
systems to optimize crop yield and waste-
water use.
D. Evaluation of effects on wildlife.
High Rate Infiltration Systems
Requirements: Permeable soil
Low suspended solids content in
wastewater
Separate storm runoff
Research Needs:
1. Treatment — Optimum combination of treat-
ing wastewater before infiltration, during soil
filtration, and after collection as renovated
water.
Nutrient removal
Pathogen removal
Increasing Carbon/ Nitrogen ratio
of wastewater
2. Soil — Relation between soil hydraulic con-
ductivity and maximum hydraulic loading
rate (different soils, wastes and climates.) Soil
management to increase treatment efficiency
(adding lime, incorporating organic carbon
and other techniques for increasing denitrifi-
cation or hydraulic conductivity).
3. Vegetation — Vegetation management to in-
crease infiltration and stimulate denitrifica-
tion.
4. Geologic Substrata — Design, management,
and monitoring systems to protect native
groundwater resources.
5. Aging of System — Effect of aging on hy-
draulic efficiency and renovation efficiency.
6. Climatic Conditions — Effect of rainfall and
temperature on infiltration recovery during
pathogen removal.
Overland-Flow Systems
Requirements: Impermeable soil which can be
graded to achieve desired slopes up
to about 8 percent
Needs: 1. Soil and terrain
a. Types and characteristics
b. Effect of percent slope and
length of slope on treatment
achieved
2. Climatic influences on micro-
biological activity
3. Aesthetics
a. Public acceptance
b. Vector nuisances
4. Site preparation and management
a. Degree of preparation and
maintenance
b. Compatibility with other land
use (such as wet land agriculture)
c. Selection vegetative covers
d. Treatment efficiency of process
5. Pretreatment required (none, primary,
secondary)
Participants
A. Earl Erickson, Michigan State University
O. C. Olson, U.S. Forest Service
P. G. Hunt, U.S. Army Corps of Engineers
R. B. Reneau, Jr., Virginia Polytechnic Institute
Herman Bouwer, U.S. Water Conservation
Laboratory
Robert Schneider, U.S. Department of Interior
William E. Sopper, Land and Water Research Insti-
tute, Penn State University
Richard E. Thomas, EPA, Robert S. Kerr Environ-
mental Research Laboratory
Richard A. Carnes, EPA-NERC
WORKSHOP GROUP 6
Options, Problems, and Economics
Agricultural Management
I would like to begin with a background statement
to place in perspective our concern with land treat-
ment of municipal sludge and effluent. Municipalities
should consider their total system for handling and
disposing of effluent or sludge. Industrial firms can
reduce water use and waste by in-plant changes in
processes and equipment, bi-product recovery, reuse
of water, and product mix. The municipality also has
a choice of treatment systems. Waste treatment sys-
tems vary widely in the amount of sludge produced.
A system evaluation should involve these objectives:
a system which achieves low cost for the total system
rather than any one component, maintains environ-
mental quality and achieves public acceptance.
Our research proposals can be broken into several
parts. The first is related to economic or technical
modeling. The second part is technical information
required for both economic analyses, and system
management and operations. Third, management and
institutional options are important factors. And
fourth, regional and community effects should be
recognized.
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WORKSHOPS
Modeling
Modeling needs involve developing, adapting and
applying research methods and procedures to the
study of the problems of land disposal of effluent and
sludge. There is a need to update the data which is
available and, throughout modeling, determine addi-
tional data needs. This process should involve devel-
opment of an information retrieval system which
would be useful to municipalities, as well as program
administrators and researchers.
Modeling would assist in multi-objective planning
and implementation. One objective may be to maxi-
mize profitability of the cropping production at a site.
Another objective might be to maximize waste treat-
ment at a site. A more likely requirement would be to
maximize environmental quality with trade-offs be-
tween profit and waste disposal objectives.
Most research information and recommendations
have been developed in a framework of maximizing
crop production. We know less about production re-
lationships as you move to higher and higher levels of
sludge application with the associated higher levels of
plant nutrients and organic solids. There are trade-
offs between the concern for crop profitability, con-
cern for waste disposal and concern for environment-
al improvement. Our modeling can provide informa-
tion which will be helpful in trade-off decision mak-
ing-
There is a need to evaluate the impacts of con-
straining sludge and effluent disposal operations, to
conduct sensitivity analyses of important factors, and
to conduct risk analyses. These analyses would be ap-
plicable to problems in choosing and managing a
total waste treatment and land application system.
Land Treatment Systems
A second search area involves an examination of
alternative systems to be employed in land treatment.
Most of our systems use components taken from other
operations. There is a need to develop new machinery
and equipment, to evaluate economies of size, and to
determine economic feasibility and cost effectiveness
of various systems under a range of climate and soil
conditions. Differences in land quality, site location,
distance, climate and rainfall, are relevant variables
in designing land application systems.
Management and Institutional Systems
A third area of research deals with management.
Management has responsibility for organization and
operation. Monitoring is important and can be a
trade-off for site preparation. Run-off control re-
duces the need for surface monitoring but may in-
crease groundwater monitoring requirement. Man-
agement analysis requires information on crop and
livestock enterprises and how they can be selected to
accomplish the objectives mentioned earlier.
In relation to crop and livestock enterprise selec-
tion, information on production relationships and nu
trient control and their relationship to environmental
improvement should be developed. Part of the man-
agement problem involves leasing arrangements anil
flexibility in leasing arrangements. Management,
basically, is important in community relations The
comments on local community relationships are re
lated to the management of these operations because
they must be separated in a way that meets public ac-
ceptance.
Crop response information is very important. Fac-
tors affecting crop response should be evaluated fur
high application rates. Land uses are important in
operating and managing land application sites. What
are the effects of loading rates, pH levels, amounts <>l
water, timing and scheduling, nutrient removal and
soil mixing.
Site management is concerned with environmental
effects. This calls for cost-benefit analyses, ecological
changes, long term effects on soils and pest popula-
tions, long term effects on water quality and the im-
portance of land reclamation to communities in the
area.
We need to examine institutional options as they
relate to incentives for farmers and communities to
use land treatment for disposing of effluent and
sludge. This would include cost sharing, taxation,
community grants, pricing of water and sewer sei -
vices and payment options. We need to examine land
use regulations in relation to land treatment as well
as methods of acquiring and controlling land, owner-
ship, leasing, and casements. Transaction costs vary
widely and would influence institutional options.
Regional and Community Effects
Regional and community effects of a large project
such as Fulton will have an impact on income in the
area. Large projects will affect employment, the tax
base, and community facilities and services needs
Regional and community effects might be important
to many communities and lead to ad|ustments. 1 he
regional adjustment implications of both large and
small land application operations should be deter-
mined.
Participants
G. Stucky, USDA-Soil Conservation Service
J. W. Turelle, USDA-Soil Conservation Service
L. Christensen, USDA-ERS
W. C. LaVeille, EPA
E. Swanson, University of Illinois
William M. Crosswhite, USDA
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
WORKSHOP GROUP 7
WORKSHOP GROUP 8
Plant Characteristics and Response—
Soil Nutrients
This workshop group on Plant Characteristics and
Response—Soil Nutrients considered plant nutrients
in relation to land application of sewage sludges and
effluents only from the standpoint of nutrient aspects,
while recognizing the importance of toxic element
considerations; those considerations being the major
responsibility of our sister workshop group on Plant
Characteristics and Response— Toxic Chemicals.
Our group believes that we need:
1. Field testing of existing information to see if it is
applicable to the concept of adding well-char-
acterized effluents and sludges to well-defined
soil-plant systems. This should include but not
be limited to:
i\. Sewage organic matter decomposition rates
and nitrogen and phosphorous availability.
b. Denitrification.
c. Phosphorous retention capacity.
d. Movement of organic and inorganic P.
e. Zinc and/ or Zn-P interactions and Zn-Cd
interactions.
f. Boron in effluents.
g. Manganese deficiencies.
2. Investigation of natural chelatkm processes.
3. Species identification and crop management for
full or maximum nutrient utilization, particular-
ly including species for use in forest and range-
land management systems.
4. Mathematical modeling of soil-plant-sludge
and/ or effluent systems.
Participants
Dean H. Urie, USDA-Forest Service, North Central
Forest Experiment Station
Robert G. Gast, University of Minnesota
James R. Peterson, Metropolitan Sanitary Depart-
ment of Greater Chicago
Richard Guldin, U.S. Army Corps of Engineers
Robert Ayers, University of California
Hurry C. Motto, Rutgers University
John F Corliss, USDA-Forest Service-Region VI
Orus L. Bennett, USDA-ARS, West Virginia
University
S \V Melsted, University of Illinois
R. Burns Sabey, Colorado State University
Donald C. Markstrom, USDA-Forest Service, Rocky
Mountain Forest and Range Experiment Station
Larry G. Merrill, Oklahoma State University
James O. Evans, USDA-Forest Service
Plant Response - Toxic Chemicals
The overriding top priority research need con-
cerning toxic chemicals is to develop criteria for con-
centrations of these chemicals in sludges that are safe
for land use on a long-term basis. The list of specific
research needs is divided into immediate and long-
term needs, recognizing that both should be initiated
and supported at the same time. The immediate needs
are those that can provide short-term contributions
to guidelines whereas long-term needs will provide
final and more reliable criteria.
The elements of primary concern are Cd, Pb, Hg,
As, Se, Zn, Cu, Ni and B, but others can be of impor-
tance in local situations or become important in the
future. These elements are of top priority because of
plant toxicities or because of potential food chain
problems.
Successful completion of these listed research
needs can lead to better management of the soil-plant
system for reduced hazards from trace elements, can
greatly improve interpretive soil maps for land use of
sludges and effluents and can prevent serious mis-
takes in site selection.
Research Needs
A.Immediate Needs
1. Tolerance of adopted plant varieties to toxic ele-
ments and the accumulation of these elements in
specific plant parts.
Determining the tolerance of plants to toxic
elements will indicate potential problems before
they become economic considerations. The de-
termination of the accumulation of toxic ele-
ments in plant parts that become part of the food
chain is essential for public health purposes.
The crops to be studied include the food, feed
and fiber producing plants as well as forest
crops, ornamentals and brushland species.
Studies should include Zn, Cu, Ni, PO4, NO^,
Pb, Cd, As, Se, Hg and B because of either toxic-
ity to plants or because of potential hazard to
animals and man.
Accumulation of toxic elements in edible por-
tions of plants in relation to climatic, soil and
management factors are of primary concern.
2. Empirical studies of the effects of soil para-
meters on toxicities of chemicals.
Impirical correlations of the toxicity of trace
elements and heavy metals which such soil para-
meters as cation-exchange capacity, surface area
of soil particles, pH and soil morphological
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WORKSHOPS
229
characteristics are an immediate need. Such cor-
relations can be useful to public and private
agencies involved in selection of sites for land
use and in comparison of land use with other dis-
posal alternatives. The preparation of interpre-
tive soil maps for uses of sludges and effluents
can be greatly improved by assessments of the
effects of soil parameters on element toxicities.
3. Methods of evaluation and development of
diagnostic techniques.
There is an immediate need for rapid labora-
tory and greenhouse methods for evaluating the
suitability of various combinations of sludges,
crops and soils for land use. Also, laboratory
diagnostic techniques for measurements of avail-
abilities of toxic elements in soils and for toxici-
ties in plants need to be developed. These
methods when standardized using characterized
soils and sludges can have utility in site selection
and in monitoring sites after land use has begun.
Rapid laboratory and greenhouse indeces can be
as useful in elucidating toxicity problems as they
have been and still are in evaluating deficiencies.
Standard samples of soils, plants and other
materials should be used to provide reliable
comparisons of analytical results obtained by
various laboratories in research and monitoring
programs.
B.Long Term Needs
1. Effects of toxic elements on yield, nutritional
and product quality of crops grown on land
treated with sludges and effluents.
Research is needed to be able to anticipate un-
desirable effects of sludges and effluents contain-
ing toxic elements. These undesirable effects
could include a) crop yield reductions, b) reduc-
tions in nutritional quality of foods and feeds
and c) decreases in the quality of fiber products.
2. Selection and breeding of plant varieties for
tolerance to and exclusion of toxic elements.
New varieties of plants may be needed to pro-
ductively use waste treated soils. The develop-
ment of such crops would insure the use of
sludge treated areas and prevent such elements
from entering the food chain. A good example
would be the development of varieties that ex-
clude Cd from edible parts of food crops.
3. Protection of the food chains.
If we substantially increase the use of sludges
and wastewater effluents by their application to
croplands we must insure the safety to humans
from the use of foods resulting from this prac-
tice. Of great, but of lesser importance, is the
necessity to determine the effects of this practice
on plants and animals themselves.
We believe that toxic chemicals possess a
greater hazard from the use of sludges than from
the use of effluents. Toxic metals and trace ele-
ments are absorbed by plants from the soil to a
much greater extent than organics and thus
should receive a higher priority. But the organ-
ics such as steriods and PCB's should not be
ignored, especially when we consider that ani-
mals ingest sludges or effluents directly when
foraging in pastures treated with these materials.
Because FDA has selected Hg, Pb, Cd, As, Sc
and Zn as the most important toxic elements in
the food chain, this group should receive top
priority. When a significant increase is obtained
in the content of any ol these elements in Iced
crops is found, feeding trails should be conduc-
ted to test the content of the clement in mc
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
7. Management of the soluble salts in sludges and
effluents.
Because of the tremendous amount of research
accomplished, and in progress, on the manage-
ment of salts in irrigated soils, the need for re-
search on the salts in sludges and effluents has
relatively low priority. The management of salts
on a basin basis is a high priority research need
in many irrigated valleys, but the salt from
sludges and effluents are likely to be only a
small part of the total salt load in such valleys.
In humid areas the dilution of salts is usually
sufficient that problems do not develop.
Recommendations:
I. From a toxic chemicals point of view effluent,
waters should be considered satisfactory if they
meet the 1972 irrigation water quality criteria.
2. A national committee assigned to establish
guidelines for sludge disposal on land should be
a product of this Workshop and the membership
for this committee should come from its par-
ticipants.
3. Point sources of trace elements into sewage sys-
tems should be greatly reduced to decrease the
loading rate in land use systems.
4. Extensive monitoring of foods, feeds, agricultur-
al products, soils and waters should be part of
presently operating land-use projects.
Participants
Rufus L. Chancy, USDA
Willard L. Lindsay, Colorado State University
John Hanway, Iowa State University
Arthur S. Newman, USDA-CSRS
Charles F. Jelinek, HEW-Food and Drug Ad-
ministration
Lisle R. Green, United States Forest Service
A. D. Day. University of Arizona
M. B. Kirkham. EPA-NERC
A! Page. University of California
Parker Pratt, University of California
Ray Miller. University of Illinois
WORKSHOP GROUP 9
Options, Problems and Economics—
Engineering Systems
Our report is in three parts. First we made some
statements of research needs and arranged them by
priority. Our priorities were simply high priority,
medium priority, and low priority. Second, we made
suggestions as to whether the research should be done
by public agencies or by private industry. We also
identified several items that we feel are more of an in-
formational need rather than real research needs
And finally, we wanted to express a couple of ideas
that we did not explore in any depth because we felt
they were more reasonably a concern of another
group.
Research Needs—High Priority
We have five high priority needs. We are concer-
ned about the water problems of small communities.
Small communities are defined as ten thousand peo-
ple or less. The collection, treatment and land appli-
cation of combined sewer system effluent should be
considered as a system. Miniaturization of municipal
systems is not the way to go for these smaller com-
munities. The small communities may need greater fi-
nancial assistance because they do not have a large
population base from which to generate the large
amounts of research funds required. On the other
hand, a small increase in per capita costs for large
cities would not be significant for the individual.
Number two is winter application and storage.
Now, this does sound like a regional problem. But let
us consider the restrictions we put on ourselves, dur-
ing several months ol the year and in many parts of
the United States we do nothing in the way of land
application because of fro/en or snow-covered
ground. Maybe there are good reasons for it and
maybe not. But what happens on frozen land when
you apply effluents and sludges? And what is the ef-
fect on lagoons when they are full of liquid and it
freezes? What happens in the way of concentration of
dilution of chemical components? What happens in-
side of a lagoon when it freezes? What is the fate of
the material we put on a watershed? Does it really go
right down the stream or what happens to it? What is
the effect on soil storage in a frozen condition? And
then there is the whole host of various engineering
modifications that would be needed in order to sim-
ply operate in the winter time. These first two re-
search needs we felt were problems for public agen-
cies.
Three, survey existing operations to develop soil,
crop, effluent relationships. This has been identified
in other reports. There are systems in operation now.
Such systems should provide an excellent opportunity
for teams from public and private groups to examine
those systems over a period of time to identif}
changes that might occur This survey and analysis
should be done soon before additional large sums of
public funds are spent for more new systems.
Number four, we think is a problem tor both pub-
lic and private research groups. This need is system-
wide monitoring. It is sufficiently important that very
early effort is recommended. A part of the problem is
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that we need standard methods of analysis. Analysts
are known to debate about which method of analysis
is the best and which one really gives the information
desired. Also, what should be the frequency of sam-
pling? How big should the sample be? What are the
statistical techniques to be satisfied in getting these
analyses? What are the parameters? There are so
many that have already been mentioned. There must
be a set of essential characteristics or essential para-
meters that must be obtained in order to accomplish
the stated objective. Then there is another list of
needs that are elective—that is, it would be desirable
to have them. But we think this is important. Remem-
ber, we are still in our high priority list of needs.
Number five is application systems for forested
areas. Again this is regional, but there is a lot of
forest land that has unique characteristics. Can we
develop application equipment that is better for
forest land than what we are using for soybeans and
corn, for example. This is research that should be
done together by public and private groups.
Research Needs—Medium Priority
Our next research need is a high-medium priority.
It deals with the development of acceptable methods
of applying raw sewage. If this is possible, the need to
separate liquids and solids would be eliminated and
costs would be reduced. We think an early part of
this is to monitor existing systems where they are ac-
tually applying raw sewage. The second part is to
develop methods of application.
We have one medium priority which we called
"landfall operations." We mean this to be other than
land application and partial recycling. Our workshop
members were generally displeased with this landfill
concept which seemed to lead to the destruction or
loss of the resources that actually are in material
going into a landfill.
The next need is a medium-low priority, probably
will be done by public groups. That is the odor prob-
lem. One of the reasons that this priority is low may
be because no satisfactory research approach has
been developed. Wherever I go people talk about
odor problems. But everybody uses a very subjective
technique—their own nose. Something surely needs
doing but we don't know what. We wanted the odor
problem identified.
Research Needs—Low Priority
We have three problems that we say are low
priority. One of these has to do with resource extrac-
tion. We can surely obtain various metals or gases or
biological materials from the sludges. There would
probably be private research to do this because if
there is money to be made from extracting these ma-
terials, it seems likely that an industry will do it. The
second low priority need is to develop covers for
storage. Several beneficial things might happen in
covered storage to the microclimate or microen-
vironment. You can keep out the precipitation, if that
is important. There is a possibility of containing the
heat that comes from the treatment process occurring
in storage. It might even help to contain odor or
change the odor or mask it. Private groups will prob-
ably do this research also. The third need is modifica-
tion of the hydraulic characteristics or sludge. We
were shown a graph earlier that hydraulic character-
istics do not change by increasing the solids content
up to a certain point. Is there a way of improving the
pumpability of sludge so that higher quantities of
solids can be moved? This research would probably
be done by private groups.
Informational Needs
A large body of knowledge is available in terms of
understanding and managing an underground aquifer.
There are a lot of possibilities of using underground
aquifers to manage water of various qualities. The
knowledge exists with those who are dealing with un-
derground waters. It might be a good opportunity to
invite the participation of the geological survey and
related water resource people dealing with under-
ground waters. It might be a good opportunity to in-
vite the participation of the geological survey and re-
lated resource people dealing with underground
aquifers.
The second informational need is to apply existing
knowledge on the control of erosion on the shore
lines of lagoons. The builders, the Corp of Engineers,
the Bureau of Reclamation, the Soil Conservation
Service, Highway Departments, all have to worry
about these problems. There are ways of doing some-
thing about reducing erosion on shore lines.
The third need is to manage aerosol transport from
spray irrigation. Here also there is some knowledge
which can be applied to the problem.
The fourth informational need is for a clearing-
house of information containing recent publications
and current research. Some way is needed, some
quick way, of having publications and research
available.
Number five is the need for standard terminology
Several groups have reported this need. It might be
worthwhile to point out a couple of the things that
were discussed about reading the literature. A re-
search man will report the kinds of observations he
makes personally. It is his own data, he can verify it,
he knows how good it is, how bad it is and what he
can do with it. Then there is secondary data. The
author can pick it up from the literature and add it on
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
to what he has obtained. We can communicate per-
sonally with colleagues and get some more informa-
tion and he can make some knowledgeable estimates
and total up quite a lot of data. Only part of this the
author knows himself, personally, as to its accuracy.
And finally, of all things extrapolate that entire data
bank and develop conclusions. This process may not
be all that bad. But each one of us writes differently
as to the conclusions we draw from the data available
to us.
Participants
Paul Schleusener, CSRS
Maurice Baker, Univeristy of Nebraska
Cliff Willey, Maryland State Environmetal Service
Jessee Russell, USDA-ERS
Walter Miller, USDA-RDS
James Pichon, Ag-Rain, Inc.
T. C. Wiliams, Williams & Works
D. L. Maase, Battelle Columbus Laboratory
Alfred Ray Harris, Forest Service, USDA-Forest
Service
W. J. Bauer, Bauer Engineering
Harold Bernard, Environmental Quality Systems
WORKSHOP GROUP 10
Political and Institutional
Constraints
The report of the workshop group on Political
and Institutional Constraints begins with a warning to
the land application community: Unless political and
institutional constraints on the land application of ef-
fluents and sludges are recognized, identified, and re-
solved, these projects will likely fail, regardless of
their technical, scientific and economic feasibility.
Constraints
Political and institutional constraints on the land
application of effluents and sludges have rarely re-
ceived systematic and scientific consideration. We
have arbitrarily listed, as examples, twelve con-
straints which may affect the implementation and
operation of land application technology. This is not
an all-inclusive listing, and other constraints will no
doubt occur to the reader.
These constraints are:
1 Public attitudes unfavorable to land application
systems.
2, Local zoning regulations which may preclude or
restrict the application of effluents or sludges to
the land. Regulations are often vague in relation
to permitted practices.
3. Land use policies which may be non-existent, or
which may be technically unrealistic.
4. Financing may be accomplished by tax levies,
revenue or general obligation bonds, service
fees, and grants-in-aid. Each approach has its
own constraints.
5. Nuisance laws which may be enforced if land ap-
plication systems cause annoyance or inconveni-
ence to any person, group, or organization.
6. Health codes which lack uniformity between
jurisdictions or may not be evenly applied to
land application systems vis-a-vis other practices
such as irrigation.
7. Permit requirements of regulatory agencies
which may involve multiple reviews and ap-
provals.
8. Monitoring requirements of regulatory agencies
may be ill-delined.
9. Fragmented regulatory agency authority results
when numerous levels and agencies of govern-
ment have jurisdiction over land application
projects.
10. Lack of national guidelines for land application
systems.
11. The belief that the consequences of implementa-
tion of a land application system will be the loss
of other desired opportunities.
12. Lack of research information in technical, sci-
entific, and socio-political areas for sound deci-
sion making on land application technology.
Research Needs
The workshop group on Political and Institutional
Constraints has identified three major study areas for
which research needs exist It is believed that studies
in these areas will produce data useful in removing
constraints which heretolore have limited large scale
use of land application techniques.
Case Histories
The first studies recommended are in the area of
Case Histories.
Research effort is needed to compile detailed case
studies of successful, as well as unsuccessful, land ap-
plication programs. The case study approach has
been developed and employed by university law and
business schools and has been found to be a powerful
educational tool for examining and understanding the
development of human institutions and interrelation-
ships.
It is proposed that the historical development of at
least ten land application projects be thoroughly re-
searched by qualified case writers. The case history
project staff should be formed on an interdisciplinary
basis and, in general, be composed of engineers.
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physical and biological scientists, and social scient-
ists. The case studies must be written in a factual, de-
tailed and historic format. Interpretations, judge-
ments, and conclusions must be avoided by the case
writers who should, however, exercise discretion with
regard to events to be included in the case studies.
Upon completion of the case studies, it is recom-
mended that a separate staff be assigned to review
and interpret the cases with the goal of identifying
common elements and similarities.
Legal Studies
The second major study area is Legal Studies.
Enabling legislation, judicial decisions, administra-
tive codes, regulations, and guidelines, and local
ordinances concerned with applying sludges and ef-
fluents on land are to be examined to determine:
l.The powers of typical local governmental units
and limitations of those powers to adopt and enforce
land-use restrictions and regulations;
2. The problems of authority to acquire land and
operate a system for the application of sludge and ef-
fluent on land;
3. The methods and restrictions on financing a sys-
tem for applying sludge and effluent on land;
4. The alternative legal and institutional arrange-
ments available for the ownership of land upon which
sludge and effluent are applied; and
5. The extent to which odor, noise, and aesthetic
degradation caused by the application of sludge and
effluent to land may be considered a nuisance.
Furthermore, studies are recommended to develop
an improved strategy for sludge and effluent manage-
ment, including changes in legislation and other types
of institutional arrangements.
Attitudes and Behavior
The third major study area is Attitudes and
Behavior.
Detailed sociological study is recommended to de-
termine individual, group, and institutional attitudes
and other factors that will affect the success or fail-
ure of specific land application programs.
Research
Finally, we recommend a priority effort by the
EPA-USDA-Universities Subcommittee on Recycling
Effluents and Sludges on Land to obtain adequate
funds for all of the scientific, technological, and
sociological research which has been identified as
needed by this Workshop Conference.
Participants
Charles E. Myers, EPA, Municipal Pollution Control
Division
S. H. Fuchs, USDA-SCS
Robert R. Barbolini, Metropolitan Sanitar> District
of Greater Chicago
Dean T. Massey, USDA-ERS, University of
Wisconsin
John M. Walker, USDA-ARS, Biological Waste
Management Laboratory
WORKSHOP DISCUSSION
COMMENT: Tom Hinesly, Office of the Under-
secretary of the Army. I wanted to point out to the
educational needs committee that their example of
Atlanta, Georgia, the Corp does have a study going
on there and I would like you to or like to get you to
send your recommendations to them right away, hut
also if you want to use an example where they don't
have one going I think it is fair to say that they are
not likely to have one in Indianapolis right away.
QUESTION: Robert Dean, EPA. Again, to the
educational group, I would like to ask them what you
do with that small segment of the population who will
not visit the site because they already know what a
stinking place it is.
ANSWER: Bob Walker, University of Illinois 1
don't know that I have the answer. There are going to
ba a few, who probably will never accept it complete-
ly. But we have to do all we can in order to get the
majority acceptance. And if you can get them in-
volved in some way, I think the secret is to get them
involved early. Now, the one project that we are talk-
ing about over at Fulton County is not typical. It is
the largest that I know of in the world and I think we
can handle these much easier if we were taking
Champaign-Urbana's sludge or some of the other
around here and I don't think we would have that
great a problem. We will never get a 1(X) percent
agreement. And with our processes the important
thing is to get the majority. Now, also recognize just a
few individuals can upset the thing if they get stirred
up enough and I think this is what you are driving at.
So the best thing that I know to do is do the best job
you can with public relations, try to involve them as
much as possible and then continue with the project.
QUESTION: Diet Ford, USDA. Just one additional
comment in relation to getting public acceptance. I
think that Mr. Bauer down at Arcola has got a good
thing going. He is taking in that operation sludge
from the local community and perhaps that might he
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
one way of winning over some of the opposition if
you are helping them solve their sludge problem all
at the same time.
ANSWER: Robert Dean, EPA. There is a lot of ap-
prehension about the very high salt content of sludges
relative to effluents. This is true. Digester sludge has
a very high conductivity and a high concentration of
salts. However, the majority of these salts will not
survive oxidation in the soil. They consist mostly of
ammonium bicarbonate and ammonium salts of or-
ganic acids. So, perhaps we need a test of the residual
salts in sludge which will give us a better measure of
what will actually enter the groundwater when sludge
is applied to the land. I think this is an acceptable re-
search need. It is one that I personally will see gets
started on.
COMMENT: Jim Menzies, Department of Agricul-
ture. I wanted to make a comment in regard to public
acceptance. We are talking about how to
psychologically deal with these problems and there
are some physical and practical ways and that is to
modify the product. We at Beltsville are attempting
to do that, to convert the sludge into compost, and
this has more ramifications than first meets the eye
because we are quite sure that you can take the neigh-
boring counties sludge and make compost and it will
be acceptable to people in the next county whereas it
won't be acceptable that it remained the other coun-
ties sludge. So, the fact that this is called compost
now and not sludge I think is of great public relations
value and maybe it is worth putting a little extra ex-
pense into it just from this point of view. Also, on the
public health point we raised the people that feel that
pasteurization is required. We know that we get a pas-
teurization effect from the composting. We know that
it is not as complete as we get from a carefully con-
trolled pasteurization heat treatment plant, but I
think this is an alternative that is a valid one to sort of
bridge the gap between those who say disinfect and
those who say try to get along without the cost of dis-
infection.
COMMENT: Bob Yeck, USDA-ARS. I would like
to comment a little further on this public relations
question. We discussed this at considerable length in
our meeting and one of the aspects that I would like
to put before the group is when you are developing a
public relations program, remind the people that they
are part of the entire ecosystem. This is one of the
bases for the recommendation or the comment that
this is a natural process and this is something that
people are a part of whether they like it or not. They
have to recognize that they don't just exist in a small
community by themselves. We spoke in our group
about the generation of waste or materials, we did a
little calculating very crudely of what the organic
output of Fulton County was, for instance, and we
rather suspect the organic output of Fulton County
that they are shipping out is considerably greater
than the organic material that they are getting back
into their area. And people have to recognize that
they are selling a product to the large city, their city
is their user and they have to expect something to
come back to them and let's try to sell them the idea
that it is a resource, but let's remind them that they
are part of the system. They are also, they don't just
stay in Fulton County, if we want to use that example.
They frequently, I am sure several of those people
travel to Chicago and use the facilities in Chicago
and some of their own material is being returned to
them. Now, I don't know how you put this in the re-
cord but these types of things are to remind the peo-
ple that they are not just living in one little area.
They are part of a bigger system and this is one of the
major points I think you must get across in public re-
lations systems.
QUESTION: B. L. Seabrook, EPA. Again, on the
subject of public relations. We had a film here,
Wealth from Waste, where they called sludge
HYDIG and they did this in England because they
did have a public relations problem and they came up
with a fancy name, Highly Digested Sludge, shortened
to HYDIG. And they found that people that objected
to sewerage and objected to sludge, didn't seem to ob-
ject to HYDIG. So, maybe a rose by any other name
is not as sweet. Anyway, it seems to me that semantics
is an important part of our business. Disposal is one
of those words. When you talk about disposal of sew-
erage wastes, a lot of people bristle, but when you
talk about land application and land utilization and
recycling and reuse, people seem to relax, and I
would suggest that we, as far as possible, avoid the
word disposal unless we actually mean disposal. And
I would suggest that when people talk about land dis-
posal, they stop using the word disposal and we talk
about application and land utilization and land reuse
or what ever term you want to call it, but unless you
mean digging a hole in the ground and dumping it in,
which is disposal, unless you mean disposal, let's stop
using the word disposal.
QUESTION: Ray Harris, USDA, Forest Service.
We spent five days here of valuable time. I think we
will all agree to that and this is so that the agencies
can start to work together on these problems. We
have addressed many important ones as high priori-
ties. For example, monitoring has to be done on a na-
tional level. Work must be done to co-ordinate and to
maintain the integrity of the data and researchers
that are doing it. Would you tell us, Darwin, how you
are going to take all of this information and put it to-
gether and put together some kind of coordinating or
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WORKSHOPS
235
informational committee so that we can start seeing
some real results of inter-disciplinary action and in-
teraction and working together on calling problems
together, something which we have never done so far,
although this is just one of probably a hundred types
of symposiums that has been held?
ANSWER: Darwin Wright, EPA. When this com-
mittee was created over a year ago, it was created
with the principal directive of developing mechan-
isms for coordinating the research between EPA,
USDA and land grant universities. The first step the
sub-committee made was to find all the players in the
game and define what we knew and what we should
know. Hopefully this will come out as a result of this
meeting this week. I might add that each member of
this group, all of you who have registered, will re-
ceive a copy of the proceedings.
Getting back to your question. Now, here we are
and what or where do we go from here? I think I
raised this issue on Monday and now that you have
all had a week to think about it, we don't really have
time to discuss it in detail, so I would like to ask you
to collect your thoughts and drop me a line.
Right now what I see happening is that the sub-
committee will get together and try to develop
mechanisms for coordinating the research. I have
heard several things suggested and I have in the back
of my mind that I think we could develop the national
strategy for land application of municipal effluents
and sludges. One of the ways of getting coordination
on a program like this is to take a number of demon-
stration sites and develop a program around each
site. Have them graphically or geographically and
climatically oriented and use existing sites wherever
possible. I think Fulton County might prove to be a
perfect place to work, depending upon the type of re-
search, development or demonstration needed. We do
need the research as soon as possible. I think we have
to consider in detail the suggestion by Mr. Myers of
examining case histories of existing sites. But it is dif-
ficult for me to say exactly where the committee is
going.
QUESTION: Tom Hinesly. Darwin, I would like
to ask one question. I would like to know what effect
this will have on the availability of research funds
because there are some of us sitting in this audience,
you know, that have ongoing research and others
have had proposals in which we have answered some
of these questions that we have come up here with
and they have been recently turned down. Our sup-
port has been discontinued. It was aimed at answering
some of these questions and I am rather confused.
Here we come back from meeting to meeting and we
outline the research needs and then sometimes we get
some of these started and then they are not continued.
So, I just wondered if you might comment on that.
ANSWER: Darwin Wright, EPA. I guess my
comment, Tom, and that is a little bit of a loaded
question because you are about in the same position
as I am, maybe we have the 118 registered here that
become vocal spokesmen to take the message back to
the people you know. I have a limited amount of
funds within the Municipal Pollution Control Divi-
sion of EPA, but I can't put all my eggs in one basket
because as everyone knows this is not a panacea and
we have other problems that have to be solved also.
QUESTION' Tom Hinesly. We are talking mainly
about an agricultural crop here and most state legis-
latures have not recognized that the colleges of agri-
culture are involved in solving municipal problems in
this area. Those of us in universities who want to do
research of this nature in colleges of agriculture have
to depend on federal funds, at least at (his point.
because I don't think we can count on our state legis-
lature as appropriating funds for us to solve this
problem, simply because they don't know that we are
involved.
ANSWER: Darwin Wright, EPA. Yes, Tom but
why don't they know you are involved? Are we
afraid to tell them?
QUESTION: Tom Hinesly. That is a problem
sometimes. It is true, because the down state people
don't want this type of research supported. And the
people who live in cities, I don't know how we get the
information to them, that they need it.
ANSWER: Darwin Wright, EPA. Well, let me just
go on record here. The sub-committee will tackle this
problem, how we get the word across to both local
people for local support and to our own State and
Federal people to support research in land applica-
tion of municipal effluents and sludges
COMMENT: Dick Ford, USDA Extension Ser-
vice. From an educational and informational stand-
point, I just wanted to support two recommendations
that were made. One, is this need for case studies.
You who have ever used case studies know they are a
very effective tool and secondly, this recommenda-
tion of needing to collect from the different universi-
ties or institutions of what has been done in certain
research fields. We talked about this quite a bit in our
group and didn't really know how to get a hold of it.
That is a good question: how do you get a hold of in-
formation from all the universities of what is going on
or has been done.
CHAIRMAN: Any other comments?
COMMENT: George Ward, Consulting Engineer. I
have gone to a lot of these conferences and I am sure
others have, but there is a rare blend of people here
that I think is unique and I want to leave with one
recommendation, that if you can and if it is practical
and if everyone here is willing, I would like to urge
that you somehow try to reschedule a similar type
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RECYCLING MUNICIPAL SLUDGES AND EFFLUENTS
meeting, hopefully starting with about the same
group and maybe blend it with others that you might
find. I don't know if you can do this or not, but most
conferences we go to, we get a lot of information, get
all excited and go home and forget about it. That may
happen again, although I got four tons of notes and I
will read them all, but I think it might be helpful to
try a similar meeting with a similar bunch and on
behalf of Oregon and our great country, I would like
to have you out our way if you would.
QUESTION: Darwin Wright. That sounds like a
pretty good idea. I am going to put Rufus Chancy on
the spot. Rufus, what do you think about having an-
other research needs workshop a year from now?
ANSWER: Rufus Chancy, USDA. When I was
talking with Darwin, I had Tom Hinesly's comments.
If we don't fund now what good is it to have ten more
conferences. We have a pretty good list of research
needs and I think that perhaps the most important
thing of all is somehow to get this work started. I
don't know whether you have to personally send
copies of this report to every member of Congress
and every member of the White House to get it star-
ted, but no more meetings are worthwhile until some
more work is on the way. That is the problem of
workshops—to list needs. We have a good list and a
big need for money right now.
COMMENT: Paul Blakeslee, State of Michigan. I
think I would like to just toss in a word of caution
about what I know is going to happen. We are talking
here about a vast number of research needs and I
think I support virtually everything that has been said
as to the unknowns. I also know that as I go back
there are going to be plans laying on the desk for
projects, for systems, for things that are mandated by
time schedules, construction time schedules in legis-
lation, in state enforcement activities and so on. At
this point in time it is a blend of all the technologists
and as long as there are serious questions on land
disposal technology, the approach is going to have to
be one of proceeding with caution and looking for all
the unknowns that we can. We are going to have to
do the same thing with some of our past historical ap-
proaches too, but Michigan is probably one of the
few states that is represented here. We are going to go
back and we are going to look and we are going to try
to make the best judgments we can, but until the
results of this thing are boiled together, we can't
make all the necessary decisions.
COMMENT: Parker Pratt, University of Califor-
nia. I would like to comment a little more op-
timistically than Rufus does, although I agree with
him, the chance to communicate and challenge other
people and be challenged with an interdisciplinary
mix of people is really worthwhile to all of us. I have
had a number of experiences recently of this kind and
1 am tremendously impressed with the ability of inter-
disciplinary mixes in a group to really come up with
some solutions to problems using data that we
already have. And I have learned a lot in this confer-
ence about problems that I didn't really know existed
and I am sure that you have and so I would say let's
get together a year from now or two years from now
with the same group and compare notes again. Even
if we feel like our list of research priorities has not
had a tremendous effect on getting more money.
There is work going on, everyone here is doing some
kind of a research project on the sludge or effluents,
maybe that is not true with all of us but we know of
work going on and getting together actually to com-
pare notes is a worthwhile objective in and of itself.
COMMENT: Robert Dean, EPA. I am speaking
for a committee on the Dimensions of the Problem.
We did recommend that a meeting such as this be
held and we carefully added the point to review new
data. Now, this does not mean data recently
developed necessarily, but data that hasn't previously
been brought to our attention and I would like to
make a plea that we spend a little more time looking
at the foreign data. I have found a great deal of very
valuable information in the Swedish literature. I will
have the more important parts of the Swedish litera-
ture translated. There is a great deal to be found in
the German literature. Not many of us read enough of
what is available in England. We have heard about
experiences in other countries, but too many people
have looked at this as if it was solely a USA problem
and if we haven't worked on it in this country, we
can't believe what we hear. I suggest, therefore, that
in the next meeting we do have some responsible
foreign delegates.
QUESTION: Harry Geyer, Extension Service,
USDA. I was interested in your comment, Darwin, of
bringing other agencies into the operation and from
the public health aspects. The thought occurred to
me that here is an area where in the Department of
Interior, the Bureau of Fish and Wild Life, we may
have the opportunity through research which they
could be conducting to assist us in making extrapola-
tions of the implications of these species having both
the carnivores and the herbivores that would be uti-
lizing some of the crops grown thereon or the plants
which would give us an insight into some of the im-
plications and concerns that we currently have.
ANSWER: Darwin Wright, EPA. Yes, I think it is
important that we pull together the other agencies.
actually the sub-committee had started on this, Tom
Hinesly from the Undersecretary of the Army's Of-
fice, and CEQ have sat in on some of our workshop
committees, and John Frey from OWRR is interested
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237
in following on with us. I think the decision that has
to be made is a higher level decision. We should
develop a coordinating committee and we sort of
have been leaning towards CEQ to do this.
All I really want to say in closing is that this mor-
ning I thought maybe I could take some notes and try
and summarize what the ten workshop chairman had
said and as I listened, I guess I was more impressed as
to what they were saying and failed to put together
any summary which probably would have taken 10 or
15 minutes anyway, so just in closing as far as the
workshops are concerned, I think you have all done
an outstanding job.
Th other thing I think we should have special rec-
ognition for, again, the arrangements committee, Sig
Melsted, Jim Evans and John Trax. So, in closing I
just want to thank each and everyone of you for com-
ing and I hope we can keep this dialogue going.
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