EPA 660/2-74-003
March 1974
Environmental Protection Technology Series
Conference on Recycling Treated
Municipal Wastewater Through
Forest and Cropland
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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EPA-660/2-74-003
March 1974
CONFERENCE ON RECYCLING TREATED MUNICIPAL
WASTEWATER THROUGH FOREST AND CROPLAND
By
William E. Sopper
Louis T. Kardos
The Pennsylvania State University
University Park, PA 16802
Project R-800678
Program Element 1BB045
Project Officer
Richard E. Thomas
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402
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Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommenda-
tion for use.
11
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Preface
The Wastewater Renovation and Conservation Project was initiated
at the Pennsylvania State University in 1962 under the direction of
Dr. Michael A. Farrell, former Director of the Agricultural Experiment
Station. An interdisciplinary team consisting of agricultural, civil,
and sanitary engineers, agronomists, foresters, geologists, ecologists,
microbiologists, biochemists and zoologists was assembled to investi-
gate the feasibility and environmental impacts of disposal of treated
municipal wastewater on the land through spray irrigation. From these
investigations the "Living Filter" concept was evolved. The term
"Living Filter" was first suggested by Mr. Gilbert Aberg, Science
Information Officer, Department of Public Information, for the title
of a film produced in 1965 depicting some of the early results of the
project. Since then, the term "Living Filter Concept" has become more
or less Synonymous with the idea of spray irrigation of municipal
wastewater on the land.
During the past 5 years there has been a tremendous increase in
interest in spray irrigation of municipal wastewater and sludge through-
out the United States. At the same time there appeared to be a lack of
definitive information on the parameters and constraints which must be
considered in the design and operation of land disposal systems under
varying environmental conditions.
To partially meet this demand for information, this symposium on
Recycling Treated Municipal Wastewater and Sludge Through Forest and
Cropland was organized and held on August 21-24, 1972 at The Pennsyl-
vania State University. The specific purpose was to review and discuss
current knowledge related to the potential of using land areas for the
disposal of wastewaters and to determine technological gaps and research
needs. The sessions were attended by over 400 participants from 45
States, Canada, Puerto Rico, Virgin Islands, and New Zealand.
The Program Planning Committee consisted of Louis T. Kardos,
Earl A. Myers, John B. Nesbitt, Richard R. Parizek, and William E.
Sopper, from The Pennsylvania State University and James 0. Evans and
Elwood L. Shafer, Jr. from the U.S. Forest Service.
Financial support was provided by The Pinchot Institute for Envi<-
ronmental Forestry Research, Northeastern Forest Experiment Station,
Forest Service, U.S. Department of Agriculture, and the Office of
Research and Monitoring, Environmental Protection Agency, Washington,
D.C.
111
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The program was conducted by the College of Agriculture and the
Institute for Research on Land and Water Resources as a continuing
education service of The Pennsylvania State University.
William E. Sopper
Louis T. Kardos
Symposium Co-Directors
IV
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CONTENTS
Keynote Address
Needed Directions in Land Disposal 1
Maurice K. Goddard
SESSION I
TREATED MUNICIPAL WASTEWATER--WHAT IS IT?
Chemical and Biological Quality of Treated Sewage Effluents 6
Joseph V. Hunter and Teresa A. Kotalik
Chemical and Biological Quality of Municipal Sludge 28
James R. Peterson, Cecil Lue-Hing and D. Zenz
FUNDAMENTAL FUNCTIONS OF THE SOIL
AND ITS ASSOCIATED BIOSPHERE
The Soil as a Physical Filter 40
Richard E. Thomas
The Soil as a Chemical Filter 47
Boyd G. Ellis
The Soil as a Biological Filter 73
Robert H. Miller
Site Selection Criteria for Wastewater Disposal -- Soils and
Hydrogeologic Considerations 95
Richard R. Parizek
SESSION II
WASTEWATER QUALITY CHANGES DURING RECYCLING
Renovation of Municipal Wastewater Through Land Disposal by
Spray Irrigation 131
Louis T. Kardos and William E. Sopper
Renovating Secondary Sewage Effluent by Groundwater Recharge
with Infiltration Basins 146
Herman Bouwer
Phosphorus and Nitrate Levels in Groundwater as Related to
Irrigation of Jack Pine with Sewage Effluent T 157
Dean H. Urie
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Restoration of Acid Spoil Banks with Treated Sewage Sludge 165
T. R. Lejcher and S. H. Kunkle
SESSION III
SOIL RESPONSES
Effects of Land Disposal of Wastewater on Soil Phosphorus
Relations 179
J. E. Hook, L. T. Kardos and W. E. Sopper
Effects of Land Disposal of Wastewater on Exchangeable Cations
and Other Chemical Elements 196
Louis T. Kardos and William E. Sopper
Factors Affecting Nitrification-Denitrification in Soils 204
F. E. Broadbent
Biotoxic Elements in Soils 215
T. D. Hinesly and R. L. Jones
Microbial Hazards in Disposing Wastewater on Soil 217
D. H. Foster and R. S. Engelbrecht
SESSION IV
VEGETATION RESPONSES
Vegetation Responses to Irrigation with Treated Municipal
Wastewater 242
William E. Sopper and Louis T. Kardos
Anatomical and Physical Properties of Red Oak and Red Pine
Irrigated with Municipal Wastewater 270
W. K. Murphey, R. L. Brisbin, N. J. Young and B. E. Cutter
OTHER ECOSYSTEM RESPONSES
Deer and Rabbit Response to the Spray Irrigation of Chlorinated
Sewage Effluent on Wild Land 286
Gene W. Wood, D. W. Simpson, and R. L. Dressier
SYSTEMS DESIGN, OPERATION, AND ECONOMICS
Sprinkler Irrigation Systems: Design and Operation Criteria 299
Earl A. Myers ,
VI
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Cost of Spray Irrigation for Wastewater Renovation 309
John B. Nesbitt
Financing Municipal Waste Water Treatment Facilities, Including
Land Utilization Systems 315
Belford L. Seabrook
SESSION V
EXAMPLES OF OPERATING AND PROPOSED SYSTEMS
Large Wastewater Irrigation Systems: Muskegon County, Michigan
and Chicago Metropolitan Region ............................... 322
W. J. Bauer and D. E. Matschke
Implementing the Chicago Prairie Plan ........................... 342
Frank L. Kudrna and George T. Kelly
Mt. Sunapee State Park, New Hampshire Spray Irrigation Project. . 348
Terrence P. Frost, Ronald E. Towne, and Harry J. Turner
Utilization of Spray Irrigation for Wastewater Disposal in
Small Residential Developments ................................ 362
T. C. Williams
Ecological and Physiological Implications of Greenbelt
Irrigation With Reclaimed Wastewater .......................... 375
V. B. Youngner, W. D. Kesner, A. R. Berg, and L. R. Green
SESSION VI
EXAMPLES OF OPERATING AND PROPOSED SYSTEMS
Municipal Wastewater Disposal on the Land as an Alternate to
Ocean Outfall. . . .............................................. 387
W. A. Cowlishaw and F. J. Roland
The Role of Land Treatment of Wastewater in the Crops of
Engineers Wastewater Management Program ....................... 400
James F. Johnson
PRESENT STATUS OF GUIDELINES
FOR LAND DISPOSAL OF WASTEWATER
Michigan's Experience with Utilizing the Ten State Guideline
for Land Disposal of Wastewater 410
Donald M. Pierce
Vll
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Fbrest Service Policy Related to the Use of National Forest
Lands for Disposal of Wastewater and Sludges 414
Olaf C. Olson and Edward A. Johnson
Spray Irrigation -- the Regulatory Agency View 420
Richard C. Rhindress
RESEARCH NEEDS
Research Needs -- Land Disposal of Municipal Sewage Wastes 435
James 0. Evans
APPENDIX
List of Participants 443
viii
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NEEDED DIRECTIONS IN LAND DISPOSAL
Maurice K. Goddard
Secretary
Department of Environmental Resources
Harrisburg, Pennsylvania
I am pleased to appear today at this "state of the art"
symposium on land disposal of municipal wastewater and sludge
and to make a pitch for increased research and development on this
fascinating area with its potential for dramatically improving
the quality of our nation's waterways.
Land disposal is far from a new idea in this country and
around the world but it is only recently that it has received the
interest and the beginnings of support which are so vital to its
success. The interest in land irrigation with waste waters comes
from the recognition of severe damage done to the aquatic
ecosystems due to discharge of various liquid wastes directly
into streams, rivers or other bodies of water. Land disposal can
serve not only to recharge the ground water supplies but also to
return nutrients to the soil. The concept is not new and has been
practiced for thousands of years in many European and Asian
countries.
As all of you are undoubtedly aware, and as the listing of
speakers for this symposium makes clear, much of the recent defini-
tive research work on land disposal was done here at Penn State
by the men who have organized this conference. Our concern now
should be to build upon this research and push for new studies
and demonstration projects to determine the parameters in which
land disposal can be a useful tool in waste water management.
One impetus for increased examination of systems for land
disposal came from the recent work in Washington on the water
pollution control bills. Had the Senate version of the legisla-
tion prevailed, it appeared that the land disposal of effluents
would almost have been mandated or at least made the subject of an
evaluation as an alternative in every case. This might not have
been that bad a result since it would have required us to face.the
issue squarely with time, talent and money rather than limping
along on a piecemeal basis. Although this requirement was not in
the final bill, the debate over it and the legislative interest in
it may still lead to expansion of the work now underway in this field.
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I do not propose today to engage in a technical discussion
on the question of land disposal. There are many others on this
program far more capable than I to give you the latest scientific
insights. Rather, I would like to address myself, speaking as
an administrator of an environmental agency, to the need for
serious consideration of this and other alternatives to our waste
problem. I have often been critical of some environmentalists
who want to have things their own way without examining all the
issues and alternatives involved in a particular problem. But
this is one instance where the environmentalists have come closer
to being on the right side.
One of the goals of the science of ecology is to maintain
a balance as much as possible in the whole life-support system of
the earth. Treating waste products so they are somewhat improved
and then discharging them into our waterways does not really meet
this goal. Taking water from underground supplies, using it and
then dumping it into the streams continually depletes groundwater.
Groundwater loss can be even more serious when wastewater is not
treated and recycled locally but piped to large distant treatment
plants for waste removal. Hence the interest of many ecolegists
in using wastewater to reclaim and fertilize land and using land
as a filter. . .a living filter if you will. . .to purify the
water. In the process, the water returns to the underground
stores from which it came.
But while ecologists have been calling for this circular
approach, engineers have been designing bigger and better treat-
ment plants and they are the ones who have been getting all the
attention. Unfortunately, they have been aided in their quest for
more and better hardware by environmental regulatory agencies which
have been more interested in specifying higher degrees of treatment
necessary than they have been in forcing an investigation of the
alternatives to the entire treatment and discharge method of
disposing of wastes. I believe a Department such as mine must
become much more involved in the question of land disposal as a
plausible alternative not only from a regulatory standpoint.but
also from an advocacy and supportive point of view.
We have at the present time about 75 land disposal operations
in the Commonwealth. Some of these land disposal facilities have
been in operation for various periods of time. Most are relatively
small projects and in their early stages were installed without
a great deal of surveillance from the Department. No permit was
necessary because there was no discharge. All this has changed
now, however. We require permits for spray irrigation systems,
just as we do for discharges, because experience has shown that some
of the effluent finally ends up in the water courses anyway. So
you have to consider them as an alternative in a total waste manage-
ment system.
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The Department now has in the final stages of preparation a
manual which we call our Spray Irrigation Manual. It will establish
the primary factors for consideration in the review of the design
and the submission of necessary reports and data for State approval.
Later in this conference you will hear from one of our water quality
people who I am sure will tell you more of our plans in this regard.
I mention it only to indicate the increasing seriousness with which
we are approaching the question of land disposal and our role as
a regulatory agency. Our manual will provide a set of guidelines
for use by the consulting engineers, geologists and soil scientists
in locating and evaluating the area needed for spray irrigation
and in designing the system for distribution of the wastewater to
the land surface.
While we and other government environmental agencies are
getting more into the business of regulation of land disposal
operations, and this is good, we should also be getting more into
the business of promoting the examination of this technique in
wider applications. Despite the apparent success of the Penn State
project, started several years ago, a more sophisticated and
ambitious plan for Muskegon County, Michigan, was greeted with
yawns and a notable lack of interest among politicians and, even
worse, among pollution control officials. The elements of the
Muskegon plan--lagoons and spray irrigation--are not new. What is
new and exciting, however, is the application of these concepts
to an entire county of some 13 communities with a combined
population of 170,000 and five industries--paper, chemical, engine
manufacturing and metal casting and plating.
Some of the project officials have been quoted as saying the
liquid effluent after just intermediate stages of treatment will
be superior to that taken from a conventional secondary treatment
plant. There are also claims that the final stage of the Muskegon
County project--the so-called living filter of the earth--will
outperform any technology now in existence. Experiments reportedly
have shown that virtually all the phosphates in domestic sewage
are removed by the time the water has moved only 12 inches down-
ward through the soil. The "living filter" also intercepts what
are probably the most persistent and dangerous pollutants in
domestic wastes, viruses. While conventional secondary treatment
does little if anything to remove viruses and chlorination and
and municipal drinking water treatment also do not touch them,
there are indications that using the earth as a "living filter"
may provide 100 per cent removal of viruses.
As attractive as the plan sounds, it met with stiff opposi-
tion from the Michigan Water Resources Commission. Much of their
opposition reportedly was based on economic grounds although the
project's backers believe long-term cost will actually be lower
than conventional treatment and also expect increased tourism
due to the cleaner waters as well as profits from crops grown on
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the irrigated lands. The state agency's objections spread to
the Federal Water Quality Administration which was needed to help
with financing. What finally broke the deadlock was the inter-
vention by Michigan Congressman Guy Vander Jagt who took on the
Muskegon County proposal as a special project. The Federal
agency, after a lot of prodding from sources all the way up to the
White House, awarded Muskegon County a research and development
grant and a construction grant. Vander Jagt and other congress-
men led the fight recently to have the House water pollution
control bill amended to equal the Senate version which was based
on the Muskegon project. As summed up by the Muskegon County
Planning Director, Roderick T. Dittmer, the whole thing sounds
deceptively simple. "Pollutants, like phosphates, are simply
natural resources out of place," Dittmer has said. "We are putting
them back in place." The time when governmental agencies concerned
with the environment can ignore something which seems to be so en-
vironmentally sound has long since passed.
Few agencies are proving this more today than the U. S. Army
Corps of Engineers. While environmentalists have had many targets
over the past few years in which the citizen ecological movement
has grown, none has been more in the line of fire than the Corps
of Engineers. And, to be fair about it, the Corps has deserved
some of the criticism it has received as have many other agencies.
To its credit now, however, the Corps is working to be more in
tune with the times and to be more aware of environmental concerns
in its actions. And one of the moves it is making is to become
involved in the entire question of land disposal systems. Having
enticed into a Corps job one of the men who had a great deal to do
with developing the Muskegon County plan, the Corps has embarked
on an effort to use its planning ability to design regional land
disposal systems like Muskegon's. The Corps will do the planning
in various areas around the country, calculate costs and benefits
of alternative strategies for waste disposal both on land and
in water and then let the communities make the final decisions and
proceed with what they want to do. The Corps has begun its work
with studies in five major cities--Cleveland, San Francisco, Chicago,
Detroit and Boston-- as well as the Codorus Creek Watershed near
Harrisburg. The Corps investigation of alternative sites will be
useful as part of the massive research effort needed on this question.
It cannot be said now whether a natural waste recycling system
is as attractive an alternative for all areas of the country, for
all sizes of population and for all types of waste as it seems to
be for Muskegon County. The answers to questions concerning locale,
soils and other variables involved in the successful operation of
land disposal system must be sought and found in the months and
years ahead. If land disposal is found to be a feasible solution
in many instances, one of the problems will be availability of land
for this purpose. At present there is little evidence of over-
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whelming public acceptance of the idea, much less demand for it.
Fanners have been rather skeptical about committing themselves
to continued use of the treated effluents. But you cannot go
ahead with such a project if people will only say they might be
willing to try it for a month or two. There must be a long-term
committment to stick with it if it is to succeed. Except for
self-contained, on-site agribusiness industries which can irrigate
their own lands, the concept is not being widely applied. For spray
irrigation of municipal wastes it appears it will be necessary for
municipalities to purchase and maintain their own lands. It seems
to me, therefore, that a tremendous amount of public information
and public relations work will have to be done to convince the far-
mers that the effluent is valuable and can be accepted.
Another problem we have seen thus far with spray irrigation is
management--or better the lack of management. Many sites have
been operated with reasonable care but on others reasonable care is
generally not given. I think it is fair to say that management has
been uniformly quite poor. Maintenance personnel rarely visit
the works, piping gets broken, sprinklers clog or stop up, field
areas get flooded, the mosquito population builds up and soils
get completely waterlogged and then the field goes anaerobic. This
is one problem which may be amenable to a solution as regulatory
agencies become more involved with the permitting and supervising
of land disposal projects.
The other problem--that of obtaining public acceptance and
willingness to put it into practice—is not so easily solvable.
This, I think, is one of the biggest things which should come from
this symposium. After hearing all the experts these next few
days tell you all they can about the "state of the art" of this
exciting field, you should be ready to go home and convince poli-
ticians, environmental agencies, ecologically-minded citizens
and everyone else that land disposal is worthy of their interest
and support for future projects on even larger scales until we find
out just how helpful this ultimate recycling idea may be.
If we all do this, the time may come in the not-too-distant
future when not only is water cleaner but crops are better and
economies are growing, all because we followed nature and its
desire for balance.
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CHEMICAL AND BIOLOGICAL QUALITY OF SEWAGE EFFLUENTS
Joseph V. Hunter and Theresa A. Kotalik
Department of Environmental Sciences
Rutgers University
Once the water carriage system for human wastes disposal became
established, the unfortunate consequences of the discharge of such
wastewaters to the environment became unpleasantly evident. These
problems were due to constituents of the wastewaters, and the
classical ones may be briefly outlined as follows:
Constituent Problem
Microorganisms Disease
Particulates Sludge banks in streams
Organics Odors, color, toxicity
Low stream dissolved oxygen
Wastewater treatment processes such as primary treatment
as outlined in Figure 1 were designed to remove easily settleable
particulates and part of the organics by primary sedimentation,
and the pathogenic microorganisms by disinfection. Secondary
treatment represents the addition of biological oxidation and
adsorption to primary treatment for the purpose of further reducing
the organic matter in effluents.
It is interesting to note from Figure 1 that those processes
that are employed to reduce the quantities of particulates and or-
ganics in turn give rise to problems of primary sludge and waste
biomass disposal. These are problems of the utmost importance,
as the disposal methodologies available represent one of the
major stresses on secondary wastewater treatment.
Even after secondary treatment, wastewater effluents can have
significant effects on the environment. Such effluents still
contain organics, salts, nutrients, particulates and varying amounts
of microorganisms depending on the degree of disinfection. It is
the purpose of this paper to delineate the physical, chemical and
biological composition of effluents so that the implications in-
volved by their disposal on, or recycling through, agricultural
and forested lands can be better understood.
6
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Wastewater
Bar Screens Screenings
Grit Chamber Grit
Primary Sedimentation Primary Sludge
(Fresh Solids)
Biological Oxidation
g g
[> § Secondary Sedimentation Waste Biomass
g § (Activated Sludge)
1 3 (Trickling Filter Humus) | &
Disinfection
Effluent
Fig. 1. Flow Diagram for a Wastewater Treatment Plant
CHEMICAL COMPOSITION
Organic Composition
In 1963, it was estimated that the BOD contributed by the
sewered population of this country was 7.3 billion pounds. Assuming
a removal efficiency of 90% for secondary treatment, 730 million
pounds of BOD entered the environment that year that had its
origins in domestic wastewater treatment plant effluents. Another
way of expressing this is that each use of water, even after sec-
ondary treatment, added 25 mg/1 BOD (equivalent to 52 mg/1 organic
matter (American Chemical Society, 1969).
As water supplies rarely contain large quantities of organic
matter, almost all the organics in effluents either entered during
the use of the water or were formed during secondary treatment.
As is true for wastewater itself, effluent organic matter is both
soluble and particulate in nature. Usual sanitary analyses find
it sufficient to divide wastewater organics into suspended matter
and soluble matter on the basis of filtration (Standard Methods for
the Analysis of Water and Wastewater, 1971) (through an asbestos
mat, glass fiber mat or membrane filter) or centrifugation (Rebhan
and Manka, 1971).
Other investigators (Rickert arid Hunter, 1967; Painter et al,
1961) have divided these organics into a settleable portion Ipb-
tained by sedimentation), a colloidal fraction (obtained by centri-
fugation) , a colloidal fraction (obtained by candle filtration or
high speed centrifugation and a soluble fraction (what remains
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when the three particulate fractions are removed). Rarely are the
particulate and soluble organics analyzed together as their natures
are sufficiently different to warrant different analytical schemes.
The general distribution of organic matter in effluents is
shown in Tables 1 and 2. Although better than half of the effluent
Table 1. Volatile Solids Distributions in an Activated Sludge
Effluent
Effluent
Fractions
Soluble
Colloidal
Supra colloidal
Settleable
Total
Winter,
mg/1
71C
2
16
1
90
1965-66a
1
79
2
18
1
_
Spring,
mg/1
62
6
24
0
92
i
1967b
%
67
7
26
0
-
Rickert and Hunter (1967).
bFrom Rickert and Hunter (1971).
CA11 values are averages from triplicate sets.
Table 2. Comparison of Organic Carbon Distributions in Effluents
Expressed as a Percentage of the Total
Type Activated Sludgea Trickling Filter3
(American) (British)
Soluble
Fine suspended ,
Coarse suspended
69
6
25
52
9
39
aFrom Rickert and Hunter (1971).
bFrom Painter et_ al (1961).
Equivalent to colloidal in Table 1.
Equivalent to the sum of settleable and supracolloidal in Table 1,
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organics are soluble, a considerable amount of the organics are
particulate. Nevertheless, most of the analyses have ignored
particulate composition. There have been three extensive in-
vestigations of the nature of the organic constituents in effluents.
The first, shown in Table 3, identified about 351 of the "soluble"
organic constituents. The next study, shown in Table 4, identi-
fied only about 25% of the soluble organics and 401 of the
particulate organics. The analytical schemes used by these in-
vestigators was one that would have identified (and have been
used to identify) at least two thirds to three quarters of the
organics found in the original wastewaters. Part of this mystery
(for the soluble constituents) was solved by the investigators whose
data is shown in Table 5. Much of the organic matter not detected
by previous investigators was found to be Fulvic, Humic and
Hymathomelanic Acids. These results were obtained for a strong
highly colored Israeli effluent, and how widely applicable they are
is unknown at present. It is obvious, however, that at least
part of the organics not determined by the first two investiga-
tions were such materials.
There have been few analyses of effluent particulates more
detailed than those shown in Table 4. Analyses of the Amino
acid constituents of effluent particulates are shown in Table 6
and those of the fatty acid contents in Table 7.
A number of the miscellaneous soluble organics found in
effluents are shown in Table 8. In addition to these, organic
acids and as gallic, citric, and lactic have been detected. It
is evident from the results presented in this section that the gen-
eral distribution of effluent organics and the major groups of ef-
fluent organics have been fairly well delineated. The molecular
nature of many of the organics still remains to be delineated.
Inorganic
The inorganic constituents of wastewater effluents are largely
soluble, as can be observed from Table 9. Little has been done
on the nature of the particulate inorganics, but the soluble
inorganics (especially nutrients) have been of considerable in-
terest and considerable research has been involved in their de-
tection and estimation.
Unlike organic constituents, which are almost wholly added
to the initial water during use, the inorganic composition of a
wastewater reflects the inorganic composition of the water supply.
As the inorganic composition of water supplies are highly variable,
it is difficult to generalize on the soluble inorganic constituents
of wastewaters.
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Table 3. Composition of an American Activated Sludge
E££luenta
Constituent Percent of Total COD
Ether extractables 10
Proteins 10
Carbohydrates and 5
polysachari des
Tannins and lignins 5
MBASD
Unidentified 65
^or a filtered sample from Bunch et a^ (1961) .
Equivalent to anionic detergents.
Table 4. Composition of a British Trickling Filter Effluenta
(as mg/1 organic carbon)
Constituent Concentration
Particulate Soluble
Fatty acids
Fatty acid esters
Proteins
Amino acids
Carbohydrates
Soluble acids
MBASb
Amino sugars
Muramic acid
Total
Total carbon
Recovery (!)
mg/1
0.12
0.12
2.74
0.00
1.39
0.13
0.05
0.38
0.05
5.0
12.90
38.80
mg/1
0
0
0.25
0.00
0.24
1.65
1.40
0.00
0.00
2.6
14.00
25.70
Painter et al (1961).
Equivalent to anionic detergents.
10
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Table 5. Composition of an Israeli Trickling Filter Effluent
with a COD of 185 mg/la
Percent of Total COD
Constituent Sample 1 Sample 2 Sample 3
Ether extractables
Anionic detergents
Carbohydrates
Tannins
Proteins
Fulvic acid
Humic acid
Hymathomelanic acid
Total
%
10.6
12.8
10.9
1.5
21.0
22.5
10.4
7.4
97.1
1
6.6
13.3
12.7
1.4
22.0
18.8
11.0
9.5
95.3
%
7.8
15.6
11.0
2.2
24.1
28.8
11.9
7.5
105.9
aFor a centrifuged sample from Rebhan and Manka (1971)
Table 6. Amino Acid Contents of an Indian Effluent Particulatesa
Dry weight
Amino acid content
iiigTi
Cystine 14.8
Lysine, histidine 26.9
Arginine 18.1
Serine, glycine, aspartic acid 36.4
Threonine, glutamic acid 34.3
Alanine 22.1
Proline Trace
Tyrosine 12.8
Methionine, valine 31.7
Phenyl alanine 27.5
Leucine, isoleucine 29.9
aFrom Subrahanyam et al (1969).
11
-------
Table 7. Fatty Acid Contents of an Indian Effluent*
Fatty acid
Concentration
Laurie
Myristic
Palmitic
Stearic
Oleic
Linoleic
Linolenic
mg/1
0.11
0.13
1.3
0.93
1.1
2.1
0.06
aFrom Viswanathan et al (1962)
Table 8. Miscellaneous Soluble Effluent Organics
Constituent
Concentration
Reference
Formic acid 91.0
Acetic acid 130.0
Propionic acid 13.7
Isobutyric acid 26.5
Butyric acid 30.7
Isovaleric acid 73.4
Valeric acid 8.1
Caproic acid 47.9
Pyrene 0.4-1.0
Nonionic surfactants 0.5-1.0
Cholesterol 15-57
Coprostanol 8-102
Uric acid 5-12
Anionic surfactants 5.6
1.6
Leucine 5
Valine 5
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 Wedgewood (1952)
mg/1 Ministry of Technology (1966)
g/1 Murtaugh and Bunch (1967)
g/1 Murtaugh and Bunch (1967)
g/1 O'Shea and Bunch (1965)
mg/la Hunter (1971)
mg/lb Hunter (1971)
mg/1 Kahn and Wayman (1964)
mg/1 Kahn and Wayman (1964)
1963 value (before conversion to biodegradable ABS).
51967 value (after conversion to biodegradable ABS).
12
-------
Table 9. Fixed Solids Distributions for an Activated Sludge
Plant Effluent
Effluent
Fraction
Soluble
Colloidal
Supra colloidal
Settleable
Winter, 1965- 66a
mg/1
223C
1
3
0
%
99
0
1
0
Spring,
rog/1
250
2
4
0
196 7b
%
97
1
2
0
Total 227 - 256 -
aFrom Rickert and Hunter (1967).
From Richkert and Hunter (1971).
Q
All values are averages from triplicate sets.
The most successful approach to this problem has been to
indicate the quantity of inorganics added to the initial supply
during domestic use. An example of this approach is presented
in Table 10. Although these are generalizations only, it is apparent
that one use of water adds to the water a considerable amount of
dissolved inorganic salts. Most of these represent the initial
amounts added to the water during use, as little or none of the
salts in Group I are removed during treatment. The inorganics
listed in Group II of Table 10 have been subjected to considerable
alteration. The phosphates found in effluents are largely
orthophosphate, and a significant amount of this is formed by the
hydrolysis of the wastewater condensed (poly) phosphates during
treatment (Bunch et al, 1961). In addition, varying amounts of
this nutrient are removed during secondary treatment.
Ammonia is formed by the hydrolysis of urea and the biological
decomposition of compounds containing organic nitrogen. Its con-
centration is reduced by assimilation, volatilization, and con-
version to nitrite and nitrate. Like aranonia and phosphate, nitrate
and nitrite are either absent from the original water supply or
present in only small amounts. Unlike ammonia and phosphate,
nitrite and nitrate are not added in substantial amounts to water
during its use (i.e. conversion to wastewater),but are formed by the
microbial oxidation of ammonia.
Although it is not completely a function of the inorganic
constituents, the pH of effluents should also be noted here. In
general, the pH of domestic wastewater will be close to seven,
13
-------
Table 10. Inorganic Constituents Added to Effluents Through
Domestic Use
Constituent Average Increment Added*
mg/1
Group I
Sodium 70
Potassium 10
Calcium IS
Magnesium 7
Chloride 75
Bicarbonate 100
Sulfate 30
Silica 15
Hardness (as CaC03) 70
Alkalinity (as CaC03) 85
Group II
Phosphate 25
Ammonium 20
Nitrate 10
Nitrite 1
aFrom American Chemical Society (1969).
somewhat higher When fresh, lower when stale, and does not change
too radically during secondary treatment. For example, the pH
of raw Bernardsville sewage has a median figure of about 7.4, while
the effluent from the activated sludge plant has a median figure of
7.2. Thus, even though much organic matter is converted to carbon
dioxide, most of this is lost to the atmosphere or enters the
bicarbonate buffer and therefore does not have a substantial effect
on pH.
BIOLOGICAL COMPOSITION
The organisms present in the effluents from secondary waste-
water treatment plants originate in the sewage entering the plant,
the atmosphere, and the population growth in response to the chemical
constituents utilized.
Effluents, therefore, would be expected to contain representa-
tives from almost all the major biological groups. Although a
considerable nunber have been identified, the major stress here has
been on pathogens or organisms indicative of the possible presence
14
-------
of pathogens. Considering the potential population, those organisms
presently identified probably represent only a small part of the
total, and it is difficult to state with any assurance of accuracy
what the dominant organisms are. Those which have been studied fall
into the following categories:
Viruses
Although infectious hepatitis is the only viral disease proven
to have been transmitted by water contaminated with sewage (Clarke
and Kabler, 1964), there is little or no information as to its
presence in secondary treatment plant effluents. On the other hand,
Coxsackie, Polio and ECHO virus have all been detected in effluents
(Clarke ejt al, 1961; Lamb et al, 1964; Primavesi and Weistenberg,
1965). In addition, ColipKa~ge~has also been detected in effluents
(Gilcreas and Kelly, 1954), not too surprising when the number of
coliform organisms is considered. Due to the fact that the present
methods are essentially only semi-quantitative, the exact numbers
of virus units in effluents is unknown. However, it has been
estimated that there are about 500 virus units/100 ml of summer
sewage (Kollins, 1966). If up to 981 of those can be removed by
activated sludge treatment (Clarke and Kabler, 1964) (found for Cox-
sackie virus), then there could be as low as 10 virus units/100 ml
of effluent.
Bacteria
As with the viruses, the major attention to the bacterial
populations of effluents has been directed towards those of sanitary
significance. Salmonella have been detected in effluents in numbers
up to 1 /100 ml (Keil, 1964). Among the various species found were:
Salmonella typhi Kapsenberg (1958)
Coetzie and Pretorius (1965)
Salmonella paratyphi Kapsenberg (1958)
Salmonella^ tyjahimurium Kapsenberg (1958)
Salmonella bareillyKapsenberg (1958)
Salmonella" sarcon Kapsenberg (1958)
Salmonella' schottmuelleri Buss and Inal (1957)
In addition to the Salmonella, clostridia can be detected in ef-
fluents (Nussbaumer, 1963), and Mycobacteria have been detected in
treated Tuberculosis sanitari effluents (Coin et al_, 1965;
Bhaskaran et al, 1960).
A considerable amount of research has been directed towards the
removals achieved during secondary treatment, and some of this is
shown in Table 11. A detailed review of the removal of pathogens
during treatment has been made by Kabler (1959). In addition to
the pathogens and indicator organisms noted above, other studies
15
-------
Table 11. Bacterial Removals Obtained by Secondary Treatment
Bacteria
Sewage
Population Reference
Biological
Treatment
Reduction
Reference
Coliform
No./ml
0.5-l-xlOe
Fecal
streptococci 5-20 x
Shigella
Salmonella
Total Count
Pseudomonas
Aerbginosa
Clostridiisn
present
4 - 12
3-18 x 10e
102
7 x 103
507
Perfringens
Mycobacterium
Tuberculosis present
Tomlinson (1962)
Burm and Vaughn (1966)
Benzie and Courchaine (1966)
Benzie and Courchaine (1966)
Allen eit al (1949)
Holt (1960)
Coetzie and Pretorius (1965)
McCoy (1957)
Tcnnlinscm_et_al (1962)
Coetzie and Fourie (1965)
Hoadley (1967)
Coetzie and Fourie (1965)
Kapsenberg (1958)
Coetzie and Pretorius (1965)
Buss and Inal (1957)
90-99 Allen et al (1949)
84-94 Allen and Brooks (1949)
90-99 Kabler (1962)
70 Kabler (1962)
90-99 Tomlinson et al (1962)
none, pop. Coetzie and Fourie (1965)
incr.
99 Hoadley (1967)
90-99 Coetzie and Fourie (1965)
66-88 Kabler (1962)
95 Bhaskaran et al (1960)
-------
have indicated the presence of Proteus sp^ (City of Johannesburg,
1963) in biologically treated effluents, and a 9 x 103 nitrite
reducing organisms and 17 x 103 nitrate reducing organisms (van
Gylswyk, 1961). It should be remembered that the microbial
populations of wastewater (Bias, 1963; Farquhar and Boyle, 1971)
and activated sludge (Farquhar and Boyle, 1971; Uhz, 1965) have
also been studied, and unquestionably most of these bacteria might
also be expected to be present in effluents.
Fungi
Three main fungi groups were found in both influents to and
effluents from biological treatment plants (Sladka and Otlova,
1968). These were as follows:
Phycomycetes
Ascomycetes
fflpdotorula species
^accharbriycetes
Deuteromycetes
Fusarium aquaeductum
roseum
Fusarium oxysporum
Yeasts were also found in effluents by another investigator,
ranging from 10 - 80 cells/ml, and included the following (Cook, 1965):
Cryptococcus Saccharomyces
JRhpdptorula Alternaria
Trichpsporons Asperquiirus
Candida' Aureobasidium
Torulppsis Fusarium
Klpeckera"" Geotrichum
Trichoderma Mocpr
Hansenula" Penicillium
In addition, effluents may also contain many of the filamentous
organisms found in activated sludge (Farquhar and Boyle, 1971).
Protozoa
A significant amount of attention has been paid to the pathogenic
Endamoeba histolytica. It has been detected in the same effluent from
which two other intestinal parasites were isolated, Trichomonas and
Chilomastiy mesnili (Metzler et al, 1958). Eudamoeba cysts have
also been detected (Dunlop ancTWang, 1961), and the following re-
lationships were found for an Israeli effluent (Kott and Kott,
17
-------
1967):
Endamoeba histolytica : 7/10 liters
Eudamoeba coli : 22/10 liters
In addition to these, the amoeba Centropyxes aculeata has also
been detected, as well as the ci liatesTStylonychi'a, S ten tor, Para-
meciun, and Carchesium (Murad and Bazer, 1970).
Effluents may also contain those protozoa known to be present
in the wastewater treatment plants (Barker, 1943; Curds and Cock-
bum, 1970) in numbers of about 100/ml. Effluents could also con-
tain the following protozoan inhabitants of tertiary lagoons
(Evans and Beuscher, 1970):
Protozoa Form
Amoeba sp. Rhizopod
Euplotes patella Ciliate
Loxophyllm helus Ciliate
Oikomonas sp. Flagellate
Pelodinium reniforme Ciliate
Phyllomitus anylophagus Flagellate
Trigonomonas compressar Flagellate
Vbrticellji campanulaCiliate
EpistylisTpliciatils Ciliate
Nematodes:
Nematodes in effluents have been reasonably well investigated
since they have been shown to be able to injest pathogens. (Chang,
1961). The major groups detected in effluents have been:
Family Reference
Rhab ditidae and Murad and Bazar (1970)
DTpTogasteridae Chang (1961)
Chang and Kabler (1962)
Calaway (1963)
Chaudhuri et al^ (1964)
Diplogasteroides Chang and Kabler (1962)
Chaudhuri et al (1964)
Dorylaimidae Chang (196TJ
Chang and Kabler (1962)
Calaway (1963)
Monochidae Chang and Kabler (1962)
Calaway (1963)
18
-------
A more detailed description of the nematodes from trickling filter
effluents and their intestinal bacteria is shown in Table 12.
Their numbers have been estimated as 200-2,000/g (Chang, 1961) and
2,000-2,500/g (Chang and Kabler, 1962) and that trickling filter
effluents contribute a major portion of the free living nematode
population in receiving waters.
Miscellaneous
A number of investigators have concerned themselves with
organisms causing schistosomiasis. It has been estimated that
either activated sludge or trickling filters can remove 99.7% of
the eggs of Shistosoma mansoni (Rowan, 1964a) but both the eggs
and miracidea have been detected in effluents (Rowan, 1964b).
In addition, algae such as Oscillator ia (Evans and Beuscher, 1970)
Euglena and Ankistrodesmus have been detected, as well as the
larva of the trickling filter fly, Psychoda.
DISINFECTION
In the United States, disinfection is practically synonymous
with chlorination. This is not true, however, in other areas,
since ozone is widely used for disinfection in Europe and chemical
disinfection of wastewater treatment plant effluents is not a
general practice in Britain.
For these reasons, and as chlorination would affect the
effluent characteristics previously mentioned, physical, chemical
and biological characteristics of effluents are frequently studied
prior to chlorination, so that the information produced would have
the widest applicability. The major exception to this generality
is for biological effluent constituents with public health
implications.
As chlorination of effluents is widely practiced in the
United States, it is necessary to indicate what effects it should
have on the effluent characteristics previously described. The
exact role this process has on colloidal and fine participates is
not too clear, but slight accumulation of sludges in chlorination
tanks could indicate some improvements in settling characteristics.
In addition to the fact that chlorination always adds chlorides,
the effect of chlorination of the inorganic constituents of ef-
fluents falls into two categories. The first involves the form
in which the chlorine is added. Chlorine gas is rarely added
directly to effluents. Instead, a concentrated "solution" of the
gas in water (or effluent) is prepared, and this is added.
19
-------
Table 12. Nematodes Found in Trickling Filter Effluents and their Intestinal Bacteria1
a
to
o
Trickling
Filter
Nematode
Bacteria
Common
Uncommon
1. Diplogasteroides Rhabiditolaimus
Rhabditis Diplogaster
Tilobus
Ironus
2. Diplogasteroides Myolaimus
Diplogaster Mononchus
Plectus
Rhabditis
Dorylaimus
Count/nematode Coli/nematode
105
9.3
92
4.5
Genera
or
Species
Pseudomonas
Proteus
A. aerogenes
E. Coli
Pseudomonas
Proteus
A. aerogenes
E. Coli
Streptoccus
Chang and Kabler (1962).
-------
When this addition occurs, the following reaction takes place,
C12 + H20 * HOCL + H Cl
forming hydrochloric acid. Thus, this practice could only tend
to lower the pH, decrease the alkalinity, and increase the acidity.
Another chlorination procedure involves the use of sodium
hypochlorite solutions, which have the opposite effect since it is
highly alkaline. Wastewater effluents, however, are usually
reasonably well buffered, and large changes in these values are
not to be expected unless exceptionally large concentrations of
disinfectants are employed.
The second involves the reactions that chlorine or rather
hypochlorite has with airmonia. These are:
NH3 + HOC1 = NH2C1 + H20
NH2C1 + HOC1 + NHC12 + H20
NHC12 + HOC1 = NC13 + H20
and result in the formation of monochloramine , dichloramine , and
nitrogen trichloride. With sufficient chlorination, (a molar
ratio of chlorine/ammonia of 2/1) , ammonia can be almost completely
removed from solution (Fair et al, 1968) .
In reactions with organic compounds in dilute aqueous solu-
tions such as effluents, chlorine (i.e. hypochlorite) can act
in either of two ways. It can oxidize functional groups or even
molecules in a manner analogous to any other oxidant. Thus,
hypochlorite can oxidize aldehydes to organic acids, but will not
in general, oxidize aliphatic alcohols (Manufacturing Chemists
Association, 1972).
OCl" + RCHO = RCOQH + Cl"
In addition, hydroquinones can be oxidized readily to quinones:
OCl" + HOCHQH = OCH + H
-------
benzenes, aromatic carboxylic acids and aromatic nitro compounds
do not react. On the other hand, aromatic amines, phenols, and
poly hydroxy phenols do form substitution products with hypo-
chlorite. The paths of these reactions are complex. With increas-
ing chlorination, up to three chlorine groups can be added.
Chlorination past this point acts like simple oxidation, resulting
in rupture of the benzene ring and the production of oxidized
fragments , (Manufacturing Chemists Association, 1972). The general
approximation for sewage is that about 2 mg/1 BOD reduction is
achieved per mg/1 chlorine added (Imhoff et al, 1971). In all
probability, as effluents are already partially oxidized, the
oxidation efficiency would not be as good.
As interesting as the reactions of chlorine with organic and
nitrogenous materials happens to be, the goal of chlorination is
sufficient to render water acceptable according to the prevailing
standards (which may attempt to achieve complete pathogen elimina-
tion). This seems relatively simple, and the general law of
disinfection was evalued in 1908 by Harriet Chick, which stated:
C11 t = K
where C is the concentration of disinfectant, t is the time
required to achieve a stated percentage kill, k is a constant
for a given disinfectant-organism system, and n is a coefficient of
dilution or reaction order (Fair et al, 1968).
Using this equation, comparisons of the degree of sensitivity
of organisms to be disinfection can_be made, and an example of this
is shown in Table 13. Not all results are so neatly defined,
however, and there seems to be considerable variation in the litera-
ture on the question of the chlorine dosage and/or residual required
to yield a stated effect. This is not too surprising, as the
effectiveness of disinfection by chlorine will not only be influenced
by time and chlorine concentration, but also whether or not the
chlorine residual is free or combined (hypochlorite or chloramine),
how well it is distributed, whether or not there are particulates
present, temperature, pH, the concentration, condition, and nature
of the organism, etc. In addition, the results reported will also
be a function of the sensitivity, precision and accuracy of the
test procedures. Keeping these limitations in mind, Table 14
gives some idea of the relative resistances of organisms to disin-
fection by chlorine. There is little question but that virus in-
activation is one of the more difficult tasks of chlorination, but
as in any disinfection process, required kills can be achieved by
lengthening the time or increasing the concentration. Within its
limits, and despite all of the problems involved, it has been a
successful disinfectant, and for domestic sewage and effluents it
will probably remain the disinfectant of choice for the near future.
22
-------
Table 13. Chick's Law Constants for Chlorination to 99% Kill
or Inactivation
Organism na K* Reference
Adenovirus 3
E. coli
Poliovirus Type 1
Coxsackie A2 Virus
0.86
0.86
0.86
0.86
0.098
0.24
1.2
6.3
Clarke et al (1956)
ButterfieicTand
Wattie (1946)
Weidenkopf (1958)
Chang et al (1960)
cL
Constants according to Fair et al with time in minutes and
concentration of HOC1 in mg/T7
SIM1ARY
The chemical and biological composition of effluents reflects
the quality of the wastewater entering the plant and the changes
that occur during the physical, chemical, and biological processes
in the plant. The chemical changes that occur during treatment
reflect the biological removal of 80-901 of the organic matter and
the production of more oxidized organics. Thus, effluents will
contain such materials as proteins, carbohydrates and soluble organic
acids which either persist through the plant or are formed in it,
such organics as Alkyl Benzene Sulfanates which have persisted
through it, or such organics as Fulvic, Humic and Hyathomelanic
Acids which are probably formed during treatment.
Interest in the removals of microorganisms during treatment
lies mainly in the area involving the efficiency of pathogen re-
moval. Sedimentation and biological oxidation do markedly reduce
pathogens, but as removals will depend (among other things) on the
concentration of the pathogen in the wastewater, their presence in
the effluent from biological treatment units can be expected and
demonstrated. In addition to wastewater bacteria, viruses, etc.
that have persisted through the plant, large numbers of protozoa
and nematodes can be developed during biological treatment.
Interest here has centered on the nematodes, which can ingest
pathogens and thus have public health significance.
Effluent chlorination is largely for disinfection. There is
little question but that the correct combinations of time and con-
centration (residual) can be achieved to obtain effective disinfec-
tion. However, actual practice may not always achieve this end,
and excessive chlorination without dechlorination may lead to
toxicity problems in receiving waters. Although chlorine can
remove nitrogen (as ammonia) from solution, it also reacts with as
23
-------
Table 14. Effect of Chlorination of Various Organisms
Group
Virus
Bacteria
Nematodes
Others
Organism
Infectious
Hepatitus
Coxsackie
Coxsackie
Echo
Poliovirus I
Coliphage B
Theiler Phage
M. tuberculosis
E. coli
Cbliforms
Total Count
Diplogaster
Cheilobus
S. mansoni
Tova and Miracidia)
S. Japonicum
Tova and Miracidia)
Chlorine
Residual
mg/1
1
15
5
1.0
1.95
0.53
0.03
0.03
1-5
2
1
0.14
0.03
1-1.2
some
2.5-3
15-45
0.2-0.6
0.2-0.6
Time
min.
30
30
2.5
3
6.5
14
10
10
120
30
30
3
10
15
15
120
1
30
30
Efficiency
Survived
Inactivated
Survived
99.6% Kill
Survived
Survived
20% Survival
Killed
99% Kill
99% Kill
Destroyed
99.9% Kill
48% Survival
99% Kill
98-99% Kill
Survived and
Mobile
Killed
Killed
Reference
Kabler (1959)
Kabler (1959)
Kabler (1959)
Kollins (1966)
Kabler (1959)
Kabler (1959)
Gilcreas and Kelly
Gilcreas and Kelly
Kabler (1959)
Kabler (1959)
(1954)
(1954)
Bhaskaran et al (1961)
Kollins (13F67~
X " f
Gilcreas and Kelly
Kabler (1959)
Kabler (1959)
Chang et al (1960)
Chang ejt aT (I960)
Kabler (1959)
Kabler (1959)
(1954)
-------
well as oxidizes organic materials. The significance of these
chlorine containing organics in effluents has not yet been
definitely established.
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27
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CHEMICAL AND BIOLOGICAL QUALITY OF MUNICIPAL SLUDGE
J. R. Peterson, C. Lue-Hing and D. R. Zenz
The Metropolitan Sanitary District of Greater Chicago
Sewage sludge is derived from the organic and inorganic matter
removed from wastewater at sewage treatment plants. The nature of
sludges depends on the wastewater sources and the method of
wastewater treatment. If waste solids are to be evaluated as a
soil amendment or as a fertilizer, it is important to understand
their chemical and biological properties. A comparison of sludge
analyses from various treatment plants would be confounded by the
individual treatment processes; therefore, some of the more common
wastewater treatment methods will be described.
CHEMICAL QUALITIES
The first treatment process is usually gravity separation of
solids from wastewater. This process is commonly known as primary
settling or primary treatment. Secondary sewage treatment may be
accomplished by physical-chemical or biological processes. The
physical-chemical processes include chemical precipitation using
lime, alum, or ferric chloride. Biological secondary treatment
includes trickling filters or some modification of the activated
sludge process in an aerobic suspended growth system which consists
of contacting primary treated with previously treated sludge.
These processes result in nutrient consumption by micro-organisms
and the formation of biological floes which are later settled out
and subsequently pumped to concentration chambers for reuse
(as activated sludge) or ultimate disposal.
-The wastewater solids separated by these primary and secondary
water treatment processes may then be dried for marketing as a low
analysis dry fertilizer, or subjected to various stabilization
treatments. Some current sludge stabilization processes include:
the Zimpro process, a high temperature and high pressure, wet
oxidation treatment which produces an aqueous suspension having a
granular ash; extended aeration in tanks or lagoons; and anaerobic
meso-or thermophilic digestion.
Following any of these latter processes the stabilized sludge
may be further concentrated by drying beds, vacuum filtration, pres-
sing, centrifugxng, or lagooning with supernatant drawoff. The
liquid fraction is high in soluble constituents. Malina and Di-
Fillippo (1971) reported that 57 percent of the nitrogen in the
waste-activated sludge digester feed was removed in the digester
28
-------
supernatant. The advantages of this further concentration is to
save lagoon storage space, reduce handling costs, or to remove
soluble chemical constituents which are usually returned to the
treatment plant. The reduction in soluble chemical constituents
has an advantage if the sludge is to be disposed of on land at
high sludge application rates.
Land application of liquid sewage sludge requires high capital
investment and is best done on a large scale. Therefore, to have
a competitive disposal system on land, the area should be capable
of safely accepting high application rates and provide some
marketable crop which will remove nutrients and protect the soil
from rapid weathering. Nitrate accumulations in groundwater have
been reported with high application rates of dairy manure
(Adriano, Pratt, and Bishop, 1971) and digested sewage sludge
(Hinesly, Braids, and Molina, 1971). Therefore, any reduction in the
nitrogen content of the sludge will permit a higher application
rate of sludge without endangering groundwater quality.
The chemical properties of sludge at various steps in the
waste-activated sludge treatment process at the Metropolitan
Sanitary District of Greater Chicago (MSDGC) West-Southwest Sewage
Treatment Plant are presented in Table 1. The sewage at this plant
includes domestic and industrial wastewater at an approximate
ratio of 3:2 plus stormwater from the Chicago area. Primary
sludge properties are not included with these data (Table 1) except
for lagoon sludge (Column 6) with supernatant removal. Part of
the waste-activated sludge is treated with FeCl3 and vacuum fil-
tered. This is blended at a ratio of 1:3 with waste-activated
sludge for thickening and fed to the digesters which are completely
mixed. The digester drawoff (Column 4) at this plant does not
have supernatant separation which may partly explain the very high
total-and Mty nitrogen concentration compared to what Anderson (1956)
reported. The lower nitrogen concentration from anaerobically
digested sludge reported by Anderson (1.3-3.1%) was due to the use
of primary sludge only while Table 1 represents waste-activated
anaerobically digested sludge. Anaerobic digestion at MSDGC
averages ca 301 reduction in volatile solids. This solids reduction
continues, to a much lesser degree, in the lagooned sludge because
of further anaerobic degradation of the organic materials present.
Analyses of the lagooned sludge which had no supernatant draw-
off was done by sampling three points in a 20 ha (50 acres) lagoon
eight months after the start of the filling operation. The filling
was done on a daily basis during these eight months after which
time the total sludge volume was 1.5 x 106 m3 when sampled. At
each point five samples from the surface to the lagoon bottom were
taken; these samples were from the surface, 2.7, 5.5, and 9.1 m
below surface, and a bottom sample (ca 15 m). A Kemmerer sampler
was used in the cover water (0-4.6 m depth) while in the thickened
29
-------
Table 1. Chemical Properties of Various Sludges Formed in the Waste-Activated Sludge Treatment
Processes at MSDGC West-Southwest Treatment Plant, Chicago, Illinois
State of Sludge Treatment
Number of analysis
Total solids (%)
Volatile solids
(1 total solids)
pH
Total nitrogens/
(% oven dry basis)
NH4-N
(1 oven dry basis)
Activated
CD
7
1.43
66.2
6.7
6.65
0.47
Vacuum
filtered §
heat dried
(2)
7
99.5
67.3
--
6.4
trace
Digested
feed!/
(3)
7
5.41
65.2
6.2
5.63
1.15
Digester
, drawoff2/
(4)
230
3.99
57
7.4
7.27
3.26
Lagooned
without
supernatant
drawoffS/
(5) ~
15
3.99
55.6
7.5
7.20
3.60
Lagooned with
supernatant
drawoff4/
(6)
30
--
35.5
7.2
2.60
1.20
I/The digester feed consists of a blend of activated sludge and vacuum filtered activated
sludge (3:1). The latter contains 101 FeCls by dry weight.
2/Digested 14 days at 29-32°C without digester supernatant withdrawal.
T/Analyses estimated after 8 months of filling a lagoon with digester drawoff*
T/Earlier sludge produced at the same treatment plant which may be up to 20 years in age and has
had supernatant removed from the lagoon (Peterson ejt al, 1971).
5/Total N analysis by Kjeldahl and Nfy-N by distillation with sludge buffered to pH 10.5.
-------
underlying slurry an Ekman dredge sampler was used. The total
solids for the whole lagoon were estimated to be equal to what
was added (3.991). The cover water-slurry partition was estimated
as 1:1 (v/v basis). Laboratory columns confirmed this partition
ratio. The lagooned sludge concentration was calculated for
the whole lagoon by averaging the concentration of the cover water
and the slurry with the assumption of a 1:1 volume ratio and a
total solids of 3.99% in the lagoon if it were remixed. The esti-
mated analyses of this sludge is presented in column 5 of Table
1. Only volatile solids showed any reduction, although NH3
gas was sometimes detectable in the area.
A comparison of the two lagooned sludges in Table 1 (Columns
5 and 6) shows the great reduction in volatile solids and
nitrogen compounds that can be expected with up to twenty years
of lagooning and periodic supernatant drawoff. The inputs to this
lagoon included Zimpro wet ash, waste-activated sludge, primary
sludge, and digested waste-activated sludge.
A comparison of sewage sludge from various parts of the United
States is presented in Table 2. The sludge types include: primary
only at Georgia and primary plus waste-activated at Minnesota,
Colorado, and Illinois. Sludge treatment included are: none at
St. Paul, Minn., addition of FeClj vacuum filtration, and heat-drying
of waste-activated sludge MSDGC West-Southwest Plant; and anaerobic
digestion of primary plus waste-activated sludges without super-
natant drawoff at MSDGC, Hanover and Calumet Plants. The Hanover
sewage is primarily from domestic sources and the Calumet and
West-Southwest sewage is a blend of domestic and industrial at an
approximate ratio of 3:2.
A comparison of Hasting and Hanover Park, two sewage treatment
plants with the least industrial waste and the same sewage treat-
ment processes indicates that Hanover Park (Column 3) has more Ca,
Mg, and Fe in its wastewater, whereas Hastings (Column 1) has more
Cr and Cu, in fact the most of any reported in Table 2. An
industrial source at Hastings is discharging Cr into the sewage
treatment plant.
A comparison of the three undigested sludges from St. Paul
(Column 2), MSDGC, West-Southwest (Column 5), and Denver (Column 6)
would be valid except for changes relating to the chemical additions
in the latter two plants. From these three plants, Chicago heat-
dried sludge had the highest concentration of total N, P, An, and
Cu, and Denver had the least total N, P, B, and Cu.
At the MSDGC, West-Southwest Sewage Treatment Plant a daily
composite of waste-activated anaerobically digested sewage sludge
was collected for 281 days between August 19, 1971 and May 31, 1972
31
-------
Table 2. Chemical Analyses of Sewage Sludges from Various Wastewater Treatment Plants
M Q n r, r rhiVam-i in ?/--
Source:
Treatment
Process:
Hastings ,
Minn.l/
Primary §
waste acti-
vated: an-
aerobic di-
gestion with-
out superna-
tant draw-
off
St. Paul,
Minn.l/
Primary §
waste acti-
vated (1:2):
undigested
Hanover, Calumet West-Southwest
Primary §
waste acti-
vated: an-
aerobic di-
gestion with-
out superna-
tant digester
drawoff
Waste-activated
FeCl3 addition:
vac. filtered:
heat -dried
Denver,
Colo.3/
Primary §
waste
activated:
FeCls and
lime: vac.
filtered:
undigest-
ed
Athens ,
Ga.4/
Primary;
anaero-
bic di-
gestion
% of dry wt. basis
Analyses
N-Total
NH4-N
P
K
Ca
Mg
Zn
B
Fe
Mn
Al
Cd
Cl
Cr
(1)
5.84
2.34
2.61
0.27
2.97
0.26
0.075
0.0013
0.45
0.015
0.65
0.00079
—
0.390
(2)
4.69
1.33
2.20
0.24
2.52
0.40
0.14
0.002
0.76
0.039
0.74
0.036
—
0.067
(3) (4)
5.57 5.20
3.63 2.40
2.59 3.90
0.68 0.55
5.05 4.20
1.64 0.60
0.069 0.35
— --_
2.22 3.68
0.07 0.14
1.21
0.0089 0.0125
0.12 0.74
0.019 0.112
(5)
6.37
trace
2.49
0.41
1.4
0.75
n- — _
0.002-0.04
5.32
0.012
—
0.028
—
0.362
(6)
4.57
—
1.75
—
7.38
0.45
0,172
0.00022
1.48
0.0253
—
—
—
—
(7)
3.5
—
0.75
0.22
1.21
0.09
0,252
0.00199
—
0.0199
—
—
—
—
-------
04
Table 2. Continued
Analyses
Cu
Ni
Pb
CD
0.12
<0.001
0.039
(2)
0.065
0.015
0.070
% of dry wt. basis
(3)
0.062
0.032
0.083
(4)
0.088
0.020
0.18
(5)
0.11
0.034
0.141
(6)
0.0324
—
""*""•
(7)
0.046
0.0026
•• •" •"
^'unpublished data from C. E. Clapp, R. H. Dowdy, and W. E. Larson, ARS, USDA, St. Paul, Minn.
^/Unpublished data, MSDGC.
-/Parza (1969).
-------
for chemical analyses. Other properties of this material were
determined on a less frequent basis. The analytical methods used
were: total N by Kjeldahl; Nfy-N by distillation at pH 10.5;
total P by Technicon Auto-Analyzer method of Stanley and
Richardson (1970); S by Leco induction furnace; metals were done
by digestion of 10 ml of the liquid sludge in 10 ml of a mixture
of concentrated H2S04 and HNOs at a ratib of 1:1, dilution to
200 ml and determination by atomic absorption except for Hg which
was by the absorption technique; Cl, pH, electrical conductivity
(E.G.), total and volatile solids, COD, BODs, volatile acids and
the hexane soluble constituents were done by standard methods
(USPHS 1971); inorganic carbon by the Bundy and Bremner (1972)
method; neutralizing power was done by repeated heating of the liquid
sludge for 1 hour on a steam bath and repeated acid titrations to
a pH 6.5 end point (Martens, 1971); alkalinity by the USPHS (1971)
method of titration to pH 4.5 end point; particle size was done by
using a Coulter Counter with 3 and 9 orifices; and cation
exchange capacity (CEC) by the H. D. Chapman (1965) method as used
for soils. The same analytical methods were used for MSDGC
sludge analyses presented in Table 1 and 2.
A detailed analytical description of anaerobically digested
waste-activated sewage sludge from the MSDGC West-Southwest Sewage
Treatment Plant is presented in Table 3. The total N concentration
is very high (7.27%) compared to other sludge sources. The soluble
nitrogen (Mty-N) content is 3.26%. This nitrogen is available
to a growing crop or may be adsorbed by the collodial fraction of
the soil. The rate of organic nitrogen mineralization for digested
sludge is less than for fresh organic wastes, e.g. animal manures
or waste-activated sludges. In addition to nitrogen, this sludge
is a source of P, Ca, Zn, Fe, and S for plants. Many other essential
and non-essential elements exist in sewage sludge. The solubility
of compounds of these elements varies with the nature of the sewage
and the chemistry of the soil following sludge application.
Jenkins and Cooper (1964) found that the dominant metal forms in
industrial sludge were hydroxides. Parsa (1970) postulated chela-
tion as an important mechanism of Zn release from sludge in soil.
In a reduced environment, such as a digester, metal-sulfides,
sulfites, -phosphates, -carbonates, -bicarbonates, -oxides, and
-hydroxides are all possible in organic compounds that might be
present. Following sludge application to soil the solubilities of
these compounds are a function of soil pH. The 4.56% Fe content
of MSDGC sludge may be advantageous according to Lagerwerff's
(1967) data. He reported that metals are competitive with Fe
in biological systems. The general order of decreasing competition
seems to be: Cu > Co > Ni > Cr > Zn > Mn > Pb.
The continued application of sewage sludge on non-calcareous
soil has been reported to cause a soil pH reduction (Hinesly,
Braids and Molina, 1972; and Lunt, 1959), although digested sludge
34
-------
Table 3.
Properties of Anaerobically Digested Waste-Activated
Sewage Sludge from MSDGC West-Southwest Sewage
Treatment Plant between August 19. 1971 and
May 31, 1972
Element-' Concentration^/ Element^/ Concentration-/
Total N
Ntfy-N
Total P
K
Ca
Mg
S
Zn
Fe
Mn
(221)
(221)
(238)
( 40)
( 43)
( 43)
( 6)
( 43)
( 43)
(43)
% dry basis
7.27
3.26
2.46
0.44
2.02
0.99
0.65
0.39
4.56
0.02
Cd
Cl
Cr
Cu
Hg
Na
Ni
Pb
Al
(43)
(78)
(42)
(43)
(46)
(43)
(43)
(39)
(40)
% dry basis
0.034
1.17
0.341
0.136
0.000038
0.38
0.08
0.106
1.04
pH (136)
Electrical conductivity (221)
Total solids (281)
Volatile solids (281)
Volatile acids as HAc (136)
1 Hexane soluble (7)
COD
BODs
Particle size (14)
Particle size (14)
Neutralizing power (3)
Neutralizing power as CaCOs (3)
Alkalinity as CaC03 (75)
Carbon, inorganic (6)
Cation exchange capacity (6)
7.4
5 mmho/an
3.99%
571 of TS
247 mg/1
12% dry basis
5400 mg/1
1140 mg/1
99% < 9
60% < 3
27 meq H+/100g
solids
2.76% dry basis
10.69% dry basis
19.3% dry basis
74 meq/lOOg
solids
— Number of analysis in parenthesis. Methods of analyses pre-
sented in text.
I/Percent dry basis x 10 » kg/metric ton.
has some neutralizing power (Table 3). The alkalinity determination
in Table 3 was done by a cold acid titration in which protein and
NfyOH added to the true value for alkalinity. The determination
of neutralizing power after heating the sludge suggests that only
35
-------
about one fourth of the reported alkalinity was due to carbonates,
bicarbonates and hydroxides. However, the inorganic carbon
(19.31) as released by 2N HC1 indicate the very slight solubility
of the inorganic carbon compounds which exist in this sludge. Even
with heat, titration with 0.01N HC1 over a 24-hour period released
only a small fraction of the inorganic carbon present. The
colloidal nature of sludge solids is reflected in a cation exchange
capacity of 74 meq/lOOg solids in a matrix which has 60% of the
particles with less than 3 micron diameter. These exchangeable
cations may be considered as available to plants.
The chemical complexity of liquid sewage sludge continues
in the soil because of the high volatile-acids and -solids which
exist in the fresh sludge. These biodegradable constituents, when
applied on soil, are subject to a vigorous change in their rate
of degradation. Thin applications of liquid sludge on the soil
surface have not resulted in reductions in water infiltration if
the sludge dried between application (Hinesly, et al. 1971).
Organic carbon does accumulate in sludge-treatecTsoTis (Peterson,
et al. 1971).
BIOLOGICAL QUALITIES
Well-stabilized sewage sludges are generally free of odors
and pathogens. This stabilization may be accomplished by anaerobic
digestion, by extended aeration, or extended lagooning of the sludge,
Poorly digested (less than 30% reduction in volatile solids) or
acidic sludge may produce odors. Well-stabilized sludge may safely
be left on the soil surface without worry of odor or vermins. This
is advantageous in that sludge can be used on a growing crop for
its nutrient and water benefits. Braids ejt al. (1970) reported
a 99% decrease of fecal coliform in 30 days oT dessication on the
soil surface. Burd (1966) reported 99.8% bacterial reduction after
30 days of mesophilic anaerobic digestion and further that
pathogenic organisms die within 7 to 10 days of digestion. Krone
(1968) reported the density of non-spore forming bacteria outside
their hosts decreased exponentially with time. Deliberate con-
tamination of tomato plants with feces, Salmonella cerro, and
Shigella alkalescens indicated that these pathogens did not survive
the dessication and the sun for more than 35 days (Rudolfs et al.
1951). Rudolfs also reported that Emdamoeba histolytica ancT
Ascaris eggs died upon dessication.
The aerobic bacteria population was reduced by two to three
logs when wet sludge (4.9% total solids) was dewatered on a vacuum
filter with Fe2S04 and lime (1:6) addition to yield a product with
65.3% total solids (Kampelmacher and Van Noorle Jansen, 1972).
They reported a 2 to 4 log reduction in enterobacteriacae with the
drying of this same sludge.
36
-------
Molina et al, (1972) observed bactericidal properties in the
liquid phase ofanaerobically digested sludge. Heat sterilization
did not eliminate bactericidal properties; therefore, parasitic"
relationships, protein, antibiotics, or nutrient competition were
ruled out as the toxic agent. Escherichici coli isolated from the
sludge had a lower mortality rate than did E^coTi from stock culture.
Soil nitrification was found to be stimulated by moderate
additions of sewage sludge ( <. 114 kg NH4-N/ha equivalent in
sludge) while higher dosing rates ( >. 228 kg Nfy-N/ha equivalent
in sludge) resulted in a lag in nitrification and an increase
in denitrification of up to 13% of the sludge N (Premi and Corn-
field, 1969). King (1971) reported that 22 to 36% of the applied
nitrogen in liquid sludge was lost with surface application. This
was by NH3 volatilization and apparent denitrification.
ACKNOWLEDGMENTS
The authors wish to thank all the personnel of the Research
and Development Department of the Metropolitan Sanitary District
of Greater Chicago for their assistance in collecting data for this
manuscript, and the Metropolitan Sanitary District of Greater
Chicago for permission to use unpublished data.
Adriano, D. C., P. E. Pratt and S. E. Bishop. 1971. Nitrate and
salt in soil and groundwaters from land disposal of dairy
manure. Soil Sci. Soc. Amer. Proc. 35, 759-762.
Amer. Public Health Assoc. 1971. Standard methods for the examina-
tion of water and wastewater. 13th Edition, APHA, New York.
Anderson, M. S, 1956. Comparative analyses of sewage sludge.
Sew. and Industrial Wastes. 28, 132-135.
Bundy, L. G. and J. M. Bremner. 1972. A simple titrimetric method
for determination of inorganic carbon in soils. Soil Sci.
Soc. Amer. Proc. 36, 273-275.
Hinesly, T. D., 0. C. Braids, and J. E. Molina. 1971. Agricultural
benefits and environmental changes resulting from the use of
digested sewage sludge on field crops. U.S. Environmental Pro-
tection Agency Reports SW-30d.
Jenkins, S. H., and J. S. Cooper. 1964. The solubility of heavy
metals present in digested sewage sludge. International Jour.
Air Water Poll. 8, 695-703.
Kampelmacher, E. H., and L. M. Van Noorle Jensen. 1972. Reduction
of bacteria in sludge treatment, Jour. Water Poll. Control
Fed. 44, 309-313.
37
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King, L. D. 1970. The effect of land disposal of liquid sewage
sludge on growth and chemical composition of coastal bermuda-
grass and rye and on soil properties, ammonia volatilization
and nitrate leaching. Ph.D. thesis, Univ. of Georgia, Univ.
Microfilm, Ann Arbor, Mich. (Dissertation Abstr. 72-10, 989).
Lagerwerff, J. V. 1967. Heavy metal contamination of soil, p
343-359 in Agriculture and The Quality of Our Environment,
Plimpton Press, Norwood, Mass.
Lunt, H. A. 1959. Digested sewage sludge for soil improvement,
Conn. Agric. Expt. Sta. Bull., 622.
Malina, J. F. and J. DiFillippo. 1971. Treatment of supernatant
and liquids associated with sludge treatment, Water and Sew.
Works, 118, R30-R38.
Martens, D. C. 1971. Availability of plant nutrients in fly ash,
Compost Science, Nov-Dec, p 15-18.
Molina, A. J. E., 0. C. Braids, and T. D. Hinesly. 1972.
Observations on bactericidal properties of digested sewage
sludge, Environ. Sci. and Tech. 6, 448-450.
Premi, P. R. and A. H. Cornfield. 1969. Incubation study of
nitrification of digested sewage sludge added to soil, Soil
Bio. and Biochem. 1, 1-4.
Rudolfs, W., L. L. Falk, and R. A. Ragotzkie. 1951. Contamination
of vegetables grown in polluted soil, Sew. and Industrial
Wastes, 23, 253-268.
Stanley, G. H. and G. R. Richardson. 1970. The automation of a
single reagent method for total phosphorus, p 305-311 in
Advances in Automated Analysis, vol. II, Industrial Analysis,
Technician Instrument Corporation, Tarrytown, New York.
DISCUSSION
Miller: I was interested in volatile acid content, isn't this
unusually high for digested sewage sludge, 247 mg/1?
Peterson: No, it's what we've been getting at the Chicago West-
Southwest treatment plant.
Miller; It seemed a little high.
Peterson: It's a high rate digestion.
Stevenson: Have you monitored the effect of this sludge application
to the soil on the groundwater?
Peterson; Yes, we have and there'll be other speakers who will
cover this.
Ludington: Both speakers have used terms like soluble and suspended,
I was wondering if they could define what those terms
are and how they were analyzed. Were conventional
standard methods of procedure used or some other method?
38
-------
Peterson: Standard methods of wastewater and water tailings were
used.
Hunter: It depends on what results I've had with the method
I'm dealing with, but in general the sizing I was
dealing with there is sedimentation for an hour for
settleable solids; supercolloidal being that which
will not settle out but which can be removed say, by
centrifugation at about 50,000 rpm, in a Sharpies
supercentrifuge or the equivalent of this. A couple
of different authors have done this. Oil being the
most variable one and here people have defined it by
chemical traces, to name one, by extremely high speed
centrifugation or by cellulose membrane filtration.
The soluble is what goes through all of these.
39
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THE SOIL AS A PHYSICAL FILTER
Richard E. Thomas
Robert S. Kerr Water Research Center
Environmental Protection Agency
The word "soil" has many definitions, but it is generally
accepted that the soil is the upper portion of the loose material
covering the surface of the earth. As such the soil is a mix-
ture of mineral particles, organic material, air, and water. The
pore space occupied by air or water may be as much as 50 percent
of the total volume, and the pathway of movement through these
pores is a maze of varying sized channels. It is the size dis-
tribution and the nature of this maze which control the capability
of the soil to filter out suspended solids that are found in
. treatment plant effluents or industrial wastewaters. In most soils,
the pore size distribution and the nature of the water movement
channels are such that suspended solids are completely removed
after short travel distances in the soil. Man has devised sev-
eral approaches to utilize this filtering capability of the soil
for disposal or renovation of municipal effluents and industrial
wastewaters. These approaches include septic tank-soil absorption
systems, cropland irrigation systems, surface disposal systems,
and groundwater recharge systems.
Each of these approaches that man has devised for utilizing
the soil to receive wastewaters is dependent on maintaining a balance
between the filtering capability of the soil and the rate of
water movement through the soil—the objective being to filter
out the suspended solids while maintaining the water movement at a
relatively high rate. The following discussion will cover some
of the research study results and practical operating experiences
that have helped to identify factors which influence the balance
between filtering capability and the rate of water movement.
Septic tank-soil absorption systems are the most widely used of
the approaches devised by man for wastewater disposal to the soil,
and there are about IS million homes in the United States utilizing
this approach. The basic concept of the approach is to provide
sufficient subsurface filtering areas to achieve long-term service
without maintenance. Failure to achieve the desired longevity and
other problems with the millions of septic tank systems installed
in the late 1940's and early 1950's stimulated a surge of research
interest to determine what caused the failure of these soil systems.
Water movement through the soil is essential to successful use
of septic tank systems, and much of the research effort has been
40
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directed to studies on soil clogging. These research efforts have
not identified the specific causal agents of soil clogging, but
they have elucidated several factors which influence the rate and
degree of clogging. The results of several research studies have
shown that clogging occurs at or near the surface of the soil
(Jones and Taylor, 1965; Thomas et al, 1966; and Winneberger et
al, 1960). The depth of the zone oF~clogging may be somewhat
greater for coarse textured soils, but for most practical applica-
tions the predominant zone of clogging is confined to a depth of
less than one inch. The most troublesome clogging usually
occurs when the soil surface becomes inundated and remains sub-
merged for an extended period of time. This clogging occurs as
an impervious mat which forms at the surface of the
soil and from a practical point of view plugs the ends of the chan-
nels through which water moves. The actual clogging is a physical
blocking of the soil pores, but it is apparent that formation of
the surface mat is the combined effects of physical, chemical, and
biochemical interactions .in the soil (McGauhey and Krone, 1967).
This surface clogging mat has two characteristics which are very
important from the practical point of view. One is the fact that
the mat is formed in conjunction with the development of anaerobic
conditions during extended periods of submergence. The other is the
fact that restoration of aerobic conditions and drying of the mat
removes most of the soil clogging directly associated with the
formation of the mat.
In summary, the research efforts directed to identifying the
causes of soil clogging elucidated three important factors to
consider in selecting management practices for applying wastewater
to the land. These three factors are (1) the zone of clogging
which reduces the water intake rate is at or near the soil surface;
(2) the most severe clogging develops in an anaerobic environment;
and (3) the severe clogging developed under anaerobic conditions
can be removed by drying the clogged surface layer of soil.
Further studies of these three factors under practical operating
conditions have verified the results of the small scale research
studies.
Looking at crop irrigation systems, we find that good operating
practices preclude the development of anaerobic conditions leading
to formation of the troublesome clogging mat. Physical clogging
of the filter for the irrigation approach should be limited to
deposition of small amounts of suspended mineral particles and
slowly degradable organic particles. The effects of these addi-
tions appear to go unnoticed at locations where wastewater irriga-
tion has been practiced for up to 80 years (Hutchins, 1939; Hyde,
1950; and Segel, 1950). Quantitative information on differences
in soil properties after 14 years of wastewater irrigation versus
a fresh water irrigation source led to the conclusion that waste-
water irrigation did not result in adverse effects that could not
41
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be corrected with minor changes in cultural practices (Day et al,
1972). The adverse differences in soil properties observed in
this study were associated with chemical interactions rather than
physical clogging by deposition.
The situation is entirely different when one considers spray
disposal and groundwater recharge approaches where the desire for
high rates of hydraulic loading frequently lead to moisture
conditions which promote development of anaerobic conditions and the
consequent severe clogging of the soil filter. This situation has
been counteracted by developing a routine management practice of
alternating wetting periods and drying periods to take advantage
of the fact that drying of the clogged surface results in recovery
of the capacity to move water. The periodicity of the wetting and
drying cycle can vary from a few days to a few weeks (Amramy, 1965;
Bouwer, 1970) depending on local conditions and the overall ob-
jectives of a given project. Much remains to be learned in this
area for improvement of techniques but we can make practical use
of current knowledge, and some recharge operations have been in
operation for several decades.
This brief discussion of the soil as a physical filter has
been directed to factors which lead to clogging of the filter and
management practices which can be used to extend the life of the
filter. These aspects of the behavior of the filter are closely
related to the chemical, biological, and hydrogeological inter-
actions which are covered in companion papers presented during
the symposium. Reference to these companion papers will strengthen
and broaden ones understanding of the function of the soil as a
filter for receiving municipal effluents or industrial wastewaters.
REFERENCES
Amramy, A. 1965. Waste treatment for groundwater recharge, Jour.
Air Water Poll. 9, 605-619. ~
Bouwer, H.1970.Water quality aspects of intermittent systems
using secondary sewage effluent, Artificial Groundwater
Recharge Conference, University of Reading, England, Paper 8.
Day, A. D., J. L. Stroehlein, and T. C. Tucker. 1972. Effects
of treatment plant effluent on soil properties, Jour. Water
Poll. Control Fed. 44(3), 372-375.
Hutchins, W. A. 1939. Sewage irrigation as practiced in the western
United States, U.S. Dept. of Agriculture, Washington, Technical
Bull. No. 675, 60 p.
Hyde, C. G. 1950. Sewage reclamation of Melbourne, Australia, Sew.
and Industrial Wastes 22(8), 1013-1015.
Jones, J. H., and G. S. Taylor. 1965. Septic tank effluent per-
colation through sands under laboratory conditions, Soil Sci.
99, 301-309.
42
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McGauhey, P. H., and R. B. Krone. 1967. Soil mantle as a waste-
water treatment system - Final Report, School of Public Health,
University of California, Berkeley, SERL Kept. No. 67-11.
Segel, A. 1950. Sewage reclamation at Fresno, California, Sew.
and Industrial Wastes 22 C81. 1011-1012.
Ihomas, k. t., w. A. Schwartz, and T. W. Bendixen. 1966. Soil
chemical changes and infiltration rate reduction under sewage
spreading, Soil Sci. Soc. of Amer. Proc. 30(5), 641-646.
Winneberger, J. H., L. Francis, S. A. Klein, and P. H. McGauhey.
1960. Biological aspects of failure of septic-tank percola-
tion systems, (Final Report) School of Public Health, Univer-
sity of California, Berkeley.
Solomon:
Kardos:
Anderson:
Thomas:
Burge:
DISCUSSION
I'd like to know what is going to happen to many of
the streams in the area if we implement this type of
a wastewater procedure. For many streams in indus-
trial areas and municipal areas, the flow consists of
between 50 to 751 wastewater. If we channel this
wastewater into the soil, undoubtedly we will raise
the soil water table, but what will happen to the
dependable flows in the streams in the area?
Well, actually you're just delaying the return flow
to the streams. It's going to go back into the
stream eventually as base flow, in other words, all
you're doing is delaying slightly the return to the
stream. You can't pile up water indefinitely in the
soil, it's got to go somewhere and eventually it ends
up in the streams. t
I have a comment or two and then a question. It seems
to me that part of the clogging might be due to case
hardening that you get because of the coagulation of
some of the larger molecular weight fragments, pro-
teins, etc. Do you find that you have any kinds of
tests that would anticipate this so that you could
alter your schedule of treatment accordingly?
Not that I am aware of, this is a pretty uncertain
art, and so far the management technique has been
developed on pretty gross values. It depends basical-
ly on the hydraulic acceptance as measured by some
device on the site.
Have you looked at the nature of that mat? Is it
particulate material or is it composed mainly of
micro-organisms ?
43
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Thomas:
Rhindress:
Thomas:
Parizek:
Thomas:
Parizek:
Schulze:
Both. There isn't a whole lot of work being done on
the mat itself. There are micro-biological cells
present and it also looks like there are materials
that were in the wastewater to start with so that
I'd say, really it is both.
Assuming a field has developed an impermeable layer
at the surface by clogging, how long or what treat-
ment would you take to regenerate that field? Can
you just plow that mat under and resume spraying or
must you let it restructure in the soil?
Where you're working with fairly coarse textured soils,
if you have a mat like I was showing here you can
recover a lot of the original conductivity by just
stopping applications for a period of time. The
resting period depends on the weather conditions but
usually in the order of magnitude of a week up to 3
weeks. In the long run you may get clogging that you
would have to go in and do physical manipulation,
plowing or some kind of disturbance of the surface
to restore the hydraulic conductivity.
I think you were showing mats developed in a flooding
or infiltration lagoon type of experiment. Are you
likely to get such mats with a spray irrigation
system?
Yes, the mats that I showed were obtained under flood-
ing conditions. However, you could get the first
mats in an irrigation type approach, if you had
restricted water movement. With the irrigation
approach, if you have good site selection and you're
working with a very well treated effluent, the clog-
ging would be a very minimal problem.
Because we need to maintain infiltration and good
drain characteristics, it seems like this plugging
problem can be alleviated by just not going to this
flooding condition.
You mentioned that anaerobic mats, the mat that is
produced under anaerobic conditions can be a very
fine layer and it usually has a black color and I
assume that it consists of fine suspended solids.
Now I recall that probably these conditions are
always very conducive to the forming of ferrous
sulphide. Usually there is some iron available under
anaerobic conditions and you can have hydrogen
sulphide formation and so ferrous sulphide could also
very well be formed and be the plugging agent. Are
there any analytical data supporting this kind of
idea?
44
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Thomas:
Sdiulze:
ThoriasT
Schul ze:
Thomas:
Hart:
Thomas:
Walker, John;
Thomas:
Ferrous sulphide is there. This is the agent that
causes most of the black color. My colleagues and
I had heated arguments many times as to whether
ferrous sulphide contributed to the clogging or
whether it was just there because of the anaerobic
conditions and is not one of the primary causes of
clogging. We do have some data published on this.
I have a publication in the Soil Science Society
Proceedings.
And what is the result now?
The ferrous sulphide is there because of the anaero-
bic conditions but it is not one of the primary causes
of the clogging.
If ferrous sulfide is not. Well, what is it then?
It's an organic matter mat of suspended material and
biological cells. That's about as close as we came
to really identifying it.
Have you any feeling for what the effect on the soil
would be if this is actually mixed within the soil
rather than placed on the surface and allowed to form
there as far as the transmissibility characteristics
that would result?
I'm not sure I understand what you mean.
Well, you're talking about putting the material
directly on the soil surface, now what if we mix it
with the soil?
You're talking about mixing a liquid or a solid like
a sludge or something like this with the soil? I
haven't any experience in this area at all. The
area I've worked in is where we were working with the
liquid waste and applying them at the surface.
Following up a comment that was made earlier, can you
only irrigate pretty clean effluent and do you have
to go to a flooding system to put down more dirty
effluent? Is there a criterion on that or is this a
point of argument?
I would say it's a point of argument, but from the
standpoint of the soil as a physical filter the
dirtier the effluent or the more solids that it
carries will limit the hydraulic load that you can put
on and keep the system going for a long period of time.
You can use a high quality effluent and go to the
infiltration approach if it's advantageous for your
area. In certain climatic regions you can manage to
45
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Kotyk:
Thomas:
Kotyk:
Thomas:
Tarquin:
Thomas:
go as high as 300 ft. per year, using the soil as a
treatment media. This is opposed to the irrigation
approach where you may go in the range of a few feet
up to as much as 6 or 7 ft. a year.
I'm wondering if you were able to determine the
distribution of water? Such as infiltration into the
soil and evaporation and evapotransporation. Were
you able to determine this at all?
We did it on one type of system, which we haven't
even talked about and I guess we won't during this
meeting, that's the spray run off system on a heavy
soil. The particular system that we studied was
located in northeast Texas, with an annual rainfall
of about 45 inches, and a potential evaporation
something slightly more than that. In this particu-
lar case, the distribution was about 201 percolating
down through the soil, about 20% loss by evaporation
and about 60% coming as a direct runoff to the
surface stream. Now this balance will be directly
dependent on the geographical location and the type
of system that you are designing or using.
Are there many systems where evaporation is the prime
mode of disposal of water?
I would say in general that with the irrigation systems
in the south-western United States the amount of the
water that is lost through evaporation is pretty sub-
stantial.
What depth of water did you put on the surface and
what was the depth of the filter. I mean physical
soil filter?
These details will be covered in a later paper by
Dr. Bouwer.
Given that you need a drying period if you want to
dispose of one inch of water, do you have any idea
whether it would be better to put it on in one minute
and dry it for 24 hours or put it on in 3 hours and
dry for 21 or put it on for 12 and dry for 12?
There's no general set rule on this. It depends on
the strength of the waste and the soil and the site.
Generally we would recommend at least several hours
for application time. At the state of the art where
we are now you'd have to do a feasibility study
concerning the best management.
46
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THE SOIL AS A CHEMICAL FILTER
Boyd G. Ellis
Department of Crop and Soil Sciences
Michigan State University
The soil has many times been referred to as "the living
filter." But it serves as a chemical filter as well through the
many organic and inorganic chemical reactions which occur when waste-
water passes through the soil profile. In addition, the soil may
chemically alter many of the materials which have been introduced
into the profile by the addition of either wastewater or sludge.
These alterations may lessen the environmental impact (for ex-
ample, through conversion of organic materials to carbon dioxide
thereby reducing the biological oxygen demand carried in the water)
or may increase the environmental hazard (for example, through the
conversion of organic nitrogen to nitrate, a much more hazardous
material). Therefore, it is imperative that the soil chemistry be
thoroughly understood and the various reactions used to optimize the
"system" when applying waste to land so that environmental hazards
will be at an absolute minimum.
In addition to purification of the wastewater passing through
the soil profile, the accumulation of ions or compounds in the
soil must not leave a residue which is harmful to either plant
growth or to the animal or human consuming the crop. Our soil is
a very precious resource. It must not be sacrificed in an effort
to clean up our water resources.
The areas of soil chemistry which are of most importance for
the soil to act as a chemical filter are: (I) ion exchange, (2)
adsorption and precipitation, and (3) chemical alteration. The
following discussion will include the theory of each process
and the importance of each process to waste disposal systems.
ION EXCHANGE
The process that we now refer to as "ion exchange" was dis-
covered in England in 1852 by a Yorkshire farmer, Thomas Way, when
he found that the addition of soil to manure reduced the loss of
ammonia (Tisdale and Nelson, 1956). Thus, the science of using
the ion exchange properties of the soil for improving the environment
had an early beginning. We now define ion exchange as the re-
versible process by which cations and anions are exchanged be-
tween solid and liquid phases and between solid phases if in close
contact with each other (Wiklander,. 1964). It is more common
47
-------
to differentiate between cation and anion exchange since cation
exchange is the dominant process in soils.
Several forms of chemical bonding may occur between ions
and the solid phase of the soil during the process of ion exchange.
They range from electrostatic to covalent in nature. When the
bonding between ions and the solid phase is largely covalent in
nature, the binding is generally more specific for the ion involved
and not reversible to other ions of similar charge. Consequently,
this type of binding is not truly exchangeable and will be covered
as an adsorption reaction. Generally, the ion exchange reactions
that we will consider here will be electrostatic and influenced by
the valence and hydration of the ion involved and the location and
density of the charge on the solid component of the soil.
The charge on the solid phase of the soil system may arise from
several souces. First, isomorphous substitution occurs in many of
the layer silicate minerals. Substitutions of aluminum for silicon
or one of several divalent ions (Fe++ and Mg++, for example) for
aluminum will give rise to a negative charge site in the mineral.
The strength of charge will also depend upon the location; i.e.
if isomorphous substitution occurs in the tetrahedral layer, the
attraction to exchangeable ions will be stronger than if the sub-
stitution occurs in the octahedral layer. For. a more complete
discussion of clay mineral structure, the reader is referred to
Clay Mineralogy by Grim (1953) or The X-ray Identification and
Crystal Structures of Clay Minerals edited by Brown (1961).Sec-
ondly, SiOH and A10H groups from exposed surfaces (generally
edges) of clay minerals and hydroxides of iron, aluminum and magne-
sium either as coatings or gels are capable of yielding exchange
sites upon dissociation. Thirdly, soil organic matter constituents
were very early recognized as having a high cation exchange capacity
(McGeorge, 1930; Mitchell, 1932). Organic exchange sites develop
from dissociation of acidic functional groups, of which carboxyl
is quantitatively most important. In addition, a broad spectrum
of acidic hydroxyls (phenolic, enolic) and tautomeric pseudo-
acids involving nitrogen in appropriate structural configurations
is likely involved (Broadbent and Bradford, 1952; Stevenson and
Butler, 1969).
A portion of the cation exchange sites is known to vary with
pH. Normally the SiOH groups will give rise to negative sites;
but A10H and FeOH can yield positive sites at low pH values (Freid
and Broeshart, 1967). Thus, the decrease in net negative charge
below pH 6.0 may not be an actual decrease of the negative charge
but an increase in the positive charge (Wiklander, 1964). All
sites originating from organic materials are expected to be pH
dependent. The pK value of carboxyl groups is such that complete
dissociation is expected by pH 7.0. Most other organic acidic
groups would require higher pH values for complete dissociation.
48
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Soil clays containing pedogenically chloritized 2:1 layer sili-
cates were shown to develop a proportionately large increment of
cation exchange capacity after brief contact with 2% sodium
?SSSateJ:pH n) according to de Villiers and Jackson (1967a,
196753. They suggested that the mechanism accounting for the
pH dependent, hysteretic cation exchange charge of the mineral
portion of many soils was deprotonation of the positive hydroxy
alumina in aluminated soils, clays and allophane.
The ions adsorbed by exchange sites may form a diffuse double
layer where the concentration of the ions will decrease exponentially
with the distance from the clay surface. Fried and Broeshart
(1967) state that it is unlikely that the adsorption of anions to
soil constituents will have the nature of a double layer. Although
solutions for cation distribution with distance from the clay surface
may be obtained by combination of Boltzman's law with Poisson's
equation, the complex nature of the cation exchange system in
natural soils makes this solution little more than a rough
approximation. The thickness of the double layer for a given soil
will be a function of valence of the exchangeable cation and total
ionic strength of the solution. In addition, Shainberg and Kemper
(1966) have shown that the hydration status of the exchangeable cation
also affects the double layer.
Gieseking and Jenny (1936) showed experimentally that soil
clays attract individual cations with different binding strengths.
In general, the greater the valence the more strongly the cation
was bound. But, in addition, rather large differences were found
within cations of the same valence. For example, potassium was
bound much more strongly than sodium. They also found considerable
hysteresis (reported earlier by Vanselow, 1932) particularly in
reactions involving monovalent-divalent exchange. Several methods
of accounting for unequal bonding energies have evolved and are
adequately summarized by Marshall (1964).
By far, the most studied exchange reaction has been that of
sodium for calcium. This reaction has been particularly important
in irrigation of soils because of the unfavorable soil structure
which will develop if the cation exchange complex becomes sufficiently
saturated with sodium so that dispersion of the soil occurs. Sodium-
adsorption ratios SAR = Na+ (Ca++ + Mg++) / 2 have been used for
a long time to evaluate the possible hazards of irrigation water
(Richards, 1954). Anions which may precipitate either calcium or
magnesium will also influence the sodium-adsorption ratios.
Eaton (1950) introduced terms to correct the soluble-sodium per-
centage in soils for the precipitation of calcium and magnesium
by carbonate and bicarbonate. Longenecker (1960) reported that
sulfate reacted differently than either nitrate or chloride in
soil systems. Thus, sodium sulfate salts replaced appreciably
more magnesium than did the sodium salt of either nitrate or chloride.
49
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These observations have been confirmed by later work (Pratt,
Branson and Chapman, 1960; Babcock and Schulz, 1963; Bower and Wil-
cox, 1965; Bower, et al., 1965; Arshad and Carson, 1967; Rao,
Page and Coleman, 19~68; Bower, Ogata and Tucker, 1968; and Pratt
and Bair, 1969). It is, therefore, necessary to consider both
the anions and cations involved in cation exchange reactions for
accurate evaluations.
Ideally, equations could be developed which would predict
accurately the exchange which would occur when a given set of
parameters is involved through the addition of wastewater. The
first attempt was made by Kerr (1928) who introduced equations based
on the law of mass action. A summary of this and other equations
which have been developed since then is given in Table 1 (adapted
from Fried and Broeshart, 1967). Generally speaking, no one
equation has been successful if applied to widely varying conditions.
All have been found to vary with soil series and most vary ap-
preciably with the particular ion pair involved in the exchange.
But, nevertheless, they do serve an important function since the
particular K may be experimentally determined in the laboratory
for a given region and set of parameters. This concept has been
very successfully applied to predicting the effects of applying
irrigation waters to soils.
Effect of Wastewater Applications on Exchangeable Cations in Soils
For the purposes of illustration, an example will be considered
for two effluents with the following composition: (1) Na = 152
ppm, Ca = 36 ppm, and Mg = 16 ppm; (2) Na = 47 ppm, Ca = 33 ppm,
and Mg = 19 ppm. It will also be assumed that they will be applied
to a Conover loam soil. Initially, a Michigan Conover loam con-
tained 15.8 me Ca/100 g, 2.1 me Mg/100 g and 0.14 me Na/100 g.
The SAR for effluent number 1 is 5.3 and for effluent number 2
it is 1.62. Using the USBA salinity handbook, the estimated
equilibrium exchangeable-sodium percentage would be 6.0 and 1.0,
respectively. Thus, after prolonged irrigation with effluent number
1, this Conover soil would be expected to increase in exchangeable
sodium percentage from 0.8 to 6% or from 0.14 me Na/100 g to
1.08. With effluent number 2 it would increase from 0.8 to II
or from 0.14 to 0.18 me Na/100 g. As previously pointed out, the
exact exchange constants would have to be determined for the soil
and effluent under consideration to yield precise values. But
it would appear that normal effluents would not lead to excessive
levels of exchangeable sodium in most soils.
Generally, exchangeable sodium percentages greater than 15%
•would be considered very serious. Even lower values may seriously
impede infiltration rates and percolation rates of water particularly
in fine textured soils. It is calculated that effluent number 1
above could not tolerate more than 430 ppm sodium, and effluent
50
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Table 1. Summary of Ion Exchange Equations Used in Soil
Science Laboratories (from Fried and Broeshart, 1967)
Common Name
Equation
Reference
Donnan
A+ Soil C"
•••^^VHH^^VM^MW^H* 1BBBBB|B^-|m
C++ Soil A+
= 1
Vageler and
Woltersdorf
(1930)
Mass action A+ Soil C++
C++ Soil A+
= K
Kerr (1928)
Gapon-
Schofield-
Eriksson-
Bolt
Langmuir
2C++ Soil
A+ Soil
C*+ Soil A+
A+ Soil C4"1
= K,
K
Gapon (1933);
Eriksson
(1952);
Schofield
(1947);
Bolt and
Peech (1953)
Boyd et al.
Vanselow
Statistical
A+ Soil
Soil (C4"1- soil + A+ soil)
A+ Soil
Soil (l-k C++ soil + A+ soil)
K2 Vanselow (1932);
Krishnamoorthy
and Overstreet
(1950)
Krishnamoorthy
et al. (1948);
Krisnnamoorthy
and Overstreet
(1950)
number 2 more than 390 ppm sodium before the soil structure would
degrade to the point of restricting water movement. Although
considerably higher than nomally found in effluents, these values
could easily be attained under certain circumstances.
51
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The effect of SAR and clay content of soils on hydraulic
conductivity is shown by data from McNeal and Coleman (1966)
and McNeal et al. (1968). At salt concentrations of 12.5 me/1
and lower, tKe relative soil hydraulic conductivity dropped to
near zero for all soils having clay contents greater than 25%
if the SAR was greater than 50. Sandy soils with less than 5%
clay showed only about 251 reduction in hydraulic conductivity even
at these extreme sodium contents. Although less drastic in the
effect on soil structure than sodium, other monovalent ions such
as potassium or lithium will also lead to reduced infiltration
rates and hydraulic conductivities.
Although they did not report SAR values or exchangeable
sodium, data by Day, Stroehlein and Tucker (1972) do show the
effects of irrigation with wastewater on infiltration rate. After
14 years of irrigation with wastewater at a rate recommended by
agriculturalists for crop production, the infiltration rate for the
areas irrigated with wastewater was 1.52 on/hr compared with 1.91
for other areas irrigated with well water and fertilized with in-
organic fertilizers. The soluble salt was 1.77 mmhos/on x 103
compared with 0.88 for the comparable treatments suggesting
that this reduced infiltration rate was the result of accumulation
fo soluble salts, presumably sodium. Their data for the sodium,
calcium and magnesium contents of sewage effluent were used
previously for my example calculation number one of SAR values
from effluents which indicated that only 6% exchangeable sodium
should result from use of this effluent. But even this amount
was sufficient to significantly reduce the infiltration rate.
Secondly, it must be remembered that they applied the wastewater
at a rate recommended for crop irrigation and not the maximum
quantity that could be applied to soils. This reduction in
infiltration rate could be attained much more quickly if higher
application rates are used.
ADSORPTION AND PRECIPITATION REACTIONS
Adsorption
Although theoretically adsorption and precipitation reactions
differ, they have sufficient similarities to merit their con-
sideration under the same general topic. Adsorption is defined
as the adhesion, in an extremely thin layer, of gas molecules,
dissolved substances or liquids to the surface of solids with
which they are in contact. Precipitation is a term used to denote
a rapid crystallization of a product of chemical reaction which is
only slightly soluble in the medium in which it is formed. Ad-
sorption differs from precipitation in that one component of the
chemical reaction which is only slightly soluble in the medium in
52
-------
which it is formed. Adsorption differs from precipitation in that
one component of the chemical reaction is already a solid. Al-
though adsorption of gases may be an asset in spreading waste-
water onto soils since the soil will eliminate many odors by this
mechanism, the remaining discussion will be restricted to adsorption
of ions and/or molecules from solution onto solids and the pre-
cipitation of certain chemicals in the soil. The ions of particu-
lar interest will be phosphorus, boron, sulfate and certain of the
heavy metals. This does not imply that other ions or compounds
may not be removed from wastewater by a similar mechanism.
Two commonly used adsorption isotherms to quantitatively de-
scribe adsorption of ions from solution onto solids are the
Freundlich isotherm (x/m = kcVn; where x/m - the quantity of
ions adsorbed per unit weight of adsorber, C - the equilibrium
concentration of the adsorbate after adsorption has occurred,
k = a constant, and n = a constant) and the Langmuir adsorption
isotherm (M) = 1 + (M) where M = the activity of the ion in
xTm Kb" ~b
moles per liter, x/m = meq of ion M adsorbed per 100 g of ad-
sorber, K = a constant related to bonding energy, and b = the maxi-
mum amount of ion M in meq/100 g that will be adsorbed by a given
adsorber. There have been many reports concerning the applica-
bility of both isotherms to adsorption in soils. These are sum-
marized by Ellis and Khezek (1972).
Using the Langmuir adsorption isotherm in studying the
soil's ability to adsorb ions from wastewater has several distinct
advantages. First, from laboratory measurements that are easily
made an adsorption maximum can be predicted. When both the
adsorption maximum and K are determined, predictions can be
made of the quantity of the particular ion that will be adsorbed
for any input level. One disadvantage of the use of adsorption
isotherms is that they give little information concerning the
mechanisms of adsorption of the ions being studied.
Considerable attention has been given to the necessity to
introduce some corrections into experimental data from adsorption
isotherms (See Fried and Broeshart, 1967, for a summary). If
appreciable quantities of the ion under study are already adsorbed
on the surface, this will cause an underestimation of x/m which leads
to underestimation of both the adsorption maximum and the con-
stant K. The amount initially adsorbed on the surface has been
shown to be accurately estimated by radioisotopic exchange techni-
ques; thus, a separate determination of the already surface ad-
sorbed ion can be made and added to the quantity of x/m deter-
mined for the adsorption isotherm. The fact that the correction
has made relatively small differences in many instances (i.e.
less than 10% correction in the adsorption maximum for the data
of Olsen and Watanabe, 1957) has led many researchers to the use
53
-------
of uncorrected data. This should only be done if it is known
that the correction is small. Otherwise, serious errors will
occur especially in the low range of the adsorption isotherm.
The determination of the adsorption of an anion should con-
tain a correction for negative adsorption (anion repulsion). A
discussion of this correction is given by de Harm and Bolt
(1963). In general, it has been ignored in determining adsorption
isotherms but this may lead to serious errors.
,»
Phosphate Adsorption
The Langmuir adsorption isotherm has been applied to phos-
phorus adsorption in soils by Fried and Shapiro (1956), Olsen
and Watanabe (1957), and Ellis and Erickson (1969). Values
determined for adsorption maxima were generally similar. The data
given in Table 2 were extracted from the report by Ellis and
Erickson as examples of the effect of soil series and horizon on
the constants from the Langmuir adsorption isotherm. Since the
maximum quantity of adsorption would not be reached except for very
high levels of phosphorus in solution, the percentage of the ad-
sorption maximum that will be saturated at 10 ppm phosphorus
in solution was calculated and the total pounds of phosphorus that
could be adsorbed per acre foot for each horizon were calculated
assuming that the bulk density of A horizons would be 1.33 g/cm3
and that of B and C horizons would be 1.5 g/on3. The minimum
adsorption was found in the dune sand which would adsorb only
77 pounds of phosphorus per acre foot and the maximum was for the
Warsaw loam which would adsorb on the average over 900 pounds of
phosphorus per acre foot. The effect of horizon is very great
and is perhaps best illustrated by the data for the Rubicon sand.
The A horizons adsorb a little more than 100 pounds phosphorus per
acre foot. But the B horizon will adsorb more than 700 pounds of
phosphorus per acre foot. The C horizon is intermediate. This
correlated well with the quantity of iron in the profile in that
iron has moved from the A horizon to the B horizon during the soil
development making the B horizon the zone of iron accumulation.
This increased iron content then accounts for the increased phosphorus
adsorption by the B horizon. The high values for adsorption of the
Warsaw laom are apparently accounted for by a high aluminum content
of this particular soil.
It is of particular interest to note that the adsorption ca-
pacity of a soil may be recovered once saturated. Ellis and
Erickson (1969) found that most soils recovered in about three
months once they were saturated. The number of times this satura-
tion and recovery cycle can be completed in a soil is unknown.
However, Blanchar and Kao (1972) reported that the adsorption
capacity of a Mexico soil changed little after 82 years of phosphate
54
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Table 2. Phosphorus Adsorption by Soils as Predicted by Langnruir Adsorption Isotherms (Data
from Ellis and Erickson, 1969).
en
en
Soil Series
Dune Sand
Rubicon
Warsaw
-
Texture
Sand
Sand
Sand
Sand
Sand
Loam
Loam
Clay Loam
Clay Loam
Gravelly Clay Loam
Sand and Gravel
Horizon
--
A-*
JT\ 1
A2
B
C
A!
B!
B21
B22
B23
D
K
KxlO"4
4.5
.77
1.98
3.99
5.78
2.96
3.73
5.83
5.20
5.92
5.45
Adsorption
Maximum
mg P/100 g
1.89
4.23
3.87
19.27
10.75
18.5
40.6
49.0
22.4
11.0
4.6
Adsorption at 10 ppm P
% of Maximum
%
94
71
86
93
95
90
92
95
94
95
95
Amount
Ibs/acre-ft
77
108
120
731
416
602
1,523
1,898
858
426
178
-------
fertilization on the Sanborn field at Columbia, Missouri.
Shapiro and Fried (1959) derived an equation describing
phosphate adsorption as primarily a mass action equation by as-
suming that phosphate adsorption was primarily an exchange with
another ion such as hydroxyl. Their data indicated that their
equation was valid but that two distinct regions of adsorption
occurred, one corresponding to low levels of phosphorus (i.e.
less than 1 ppm P in solution) and the other describing ad-
sorption at much higher levels. Their equation is:
P (solid) = KpP (solid) / p + P (solid)max. This equation reduces
to the Langmuir adsorption equation if the following identities
are made: P (solid) = x/m; £ = 1/K. „._; p = (M); and P (solid)
max. = b. P Langmuir
Sulfate Adsorption
The adsorption of sulfate by soils is of less interest in
applying wastewaters so it will be only briefly reviewed here.
Chao, Harward and Fang (1962 and 1963) reported that sulfate
adsorption by soils could be described by the Freundlich isotherm.
The sulfate retained was in kinetic equilibrium with sulfate in
solution. Several factors affected the adsorption including
the cation accompanying the sulfate and the cation that was the
exchangeable cation. As neutriality was approached, sulfate ad-
sorption decreased considerably regardless of the type of saturating
cation. Bornemisza and Llanos (1967) reported that the presence
of phosphates enhanced slightly the movement of sulfate. They
found no adsorption maxima even at high applications of sulfate.
Aylmore, Karim and Quirk (1967) found that sulfate adsorption
conformed to a Langmuir-type equation but that more than one region
of adsorption existed. Barrow (1967) also found that sulfate
adsorption did not always fit a Langmuir isotherm. Hasan, Fox and
Boyd (1970) found adsorption maxima for several surface soils
developed from volcanic ash varied from 80 to 1,500 mg S/1000 g
soil. Barrow (1970) reported that the ratio of sulfate:phosphate
adsorbed by soils increased 3-fold as the soil pH decreased from
6 to 4. It would be concluded from this that sulfate adsorption
would not be at its maximum at the pH of most wastewater.
Boron Adsorption
The adsorption of boron by soils has been recently reviewed
by Ellis and Khezek (1972). Boron adsorption has been described by
the Langmuir adsorption equation (Biggar and Fireman, I960;
Kingston, 1964; Hatcher and Bower, 1958). But the Langmuir ad-
sorption equation appears to be valid only over certain limited
concentrations. A development of particular interest to applica-
56
-------
tion of wastewater was made when several researchers (Thomas, 1944;
Hiester and Vermeulen, 1952; and Vermeulen and Hiester, 1954)
developed equations describing adsorption and desorption of boron
during the flow of solutions through columns of exchangers where
the adsorption equilibrium can be expressed by Langmuir's
adsorption equation. .Application of these equations to predict
boron removal from soils by leaching was made by Hatcher and Bower
(1958). It has been reported by Rhoades, Ingvalson, and Hatcher
(1970a) that the Langmuir desorption theory underestimated the
quantity of leaching required to elute toxic levels of soluble
boron from soils. But, on the other hand, Tanji (1970) found
good agreement and found that the chromatographic equations to-
gether with the Langmuir isotherm were adequate.
Soil chemically filter boron from solution by four mechanisms.
First, iron and aluminum hydroxy compounds present in soils as
coatings on or associated with clay minerals adsorb boron (Hatcher,
Bower, and Clark, 1967; Sims and Bingham, 1968a,b). Secondly,
iron or aluminum oxides will adsorb large quantities of boron
(Scharrer, Ktihn, and Llittmer, 1956). Third, clay minerals, and
particulary micaceous-type clay minerals, will absorb boron into
their lattice (Couch and Grim, 1968"; Fleet, 1965; and Sims and
Bingham, 1967). This absorption is suggested to begin with chemical
adsorption of B(QH)4 at the tetrahedral portion of the edge of
an illite flake. The anion gains stability by forming a weak
ionic bond with the net positive charge expected at the mineral's
edge. The second step is solid diffusion of boron into the
interior of the crystal through crystal defects. Finally,
magnesium-hydroxy clusters or coatings that exist on the weathering
surfaces of ferromagnesium minerals have recently been shown
to adsorb boron by bonding through the hydroxyl groups paralleling
the bonding by iron and aluminum hydroxides (Rhoades, Ingvalson,
and Hatcher, 1970b).
Heavy Metal Adsorption
The adsorption of zinc, copper, iron and mangane-.e by soils
was reviewed by Ellis and Khezek (1972). In addition, many other
heavy metals, for example, nickel, chromium, cadmium, lead, mer-
cury and cobalt, may enter into wastewater as a discharge from
industry. The effects of these heavy metals are largely unknown.
For those metals studied, a small fraction of the metal added
appears to be bound very tightly to specific sites in the soils.
These reactions for cobalt have been reported by Hodgson (1960);
Hodgson and Tiller (1961); Hodgson, Geering and Fellows (1964);
and Hodgson, Tiller and Fellows (1960). Zinc adsorption has
been shown to be related to silicic acid by Tiller (1967).
Sharpless, Wallihan and Peterson (1969) found that large quantities
of zinc were rapidly adsorbed as an exchangeable cation. This
57
-------
was followed by a slow conversion to a non-exchangeable acid soluble
form of zinc but the rate of conversion varied greatly from soil
to soil. Zinc adsorption was described by the Langmuir adsorption
equation by Udo, Bohn, and Tucker (1970). At moderately high
levels to zinc they found that zinc was precipitated as zinc
hydroxide, a subject to be discussed later in this paper. Although
it was shown that adsorption of zinc was described by a Langmuir
adsorption isotherm, insufficient data are now present to warrant
the conclusion that the Langmuir isotherm can be used to describe
adsorption of heavy metals by a wide range of soils.
Precipitation Reactions in Soils
Many of the ion species introduced in wastewater may combine
with other ions in the soil solution to produce an insoluble product.
If a stable, solid phase is formed, the levels of ions left in
solution may be described by a solubility product. Consider the
following general reaction:
aA + bB 1L + mM +
If the law of mass action is obeyed, the rate of the forward and
reverse reactions will be given by:
Rate forward = kf (A)a(B)b ..... and
Rate reverse = k
The activities of each component in equations above are given by
(A) , (B) , (L) , and (M) . The rate of the forward and the reverse
reaction must be equal at equilibrium; therefore:
kf(A)a(B)b . . . . - krCL)1(M)m ....
The equilibrium constant is then given by:
Keq - Vk
(A)(B)
For the specific case of the solubility product, the activity of the
solid phase is assumed to be one (or not to change) and the equation
reduced to:
Solubility products have been applied to studies of soil
phosphorus in many different ways. Schofield (1955) and Aslying
(1954) have suggested that soil phosphorus could be characterized
by the use of "lime phosphate potentials" or the chemical potential
58
-------
of raonocalcium phosphate. Utilizing this principle, a plot of
l/2pCa + pH2P04 as determined in a 0.01 N CaCl2 solution against
pH - l/2pCa should define the values of phosphorus in solution for
any soil. These potentials have been measured and reported by
many investigators (Henze, 1963; Ulrich, 1961; Mattingly et al.,
1963; Gough and Beaton, 1963; Scheffer and Ulrich, 1960; and~lhite
and Beckett, 1964). It can be easily shown that the lime-phosphate
potentials are really a rearrangement of solubility products.
Lindsay and Moreno (I960) prepared a solubility phase diagram
relating pH and pF^PCty to the solubility of the common phosphate
minerals found in soils. While their diagram does show the points
of maximum I^PCty in solution under the conditions of their
assumptions and point out vividly the effects of soil pH on
phosphate solubility, it is also quite similar to the lime-
phosphate potentials since both originate from the same solubility
products.
In acid soils, points for phosphate potentials many times do
not fall on solubility lines for calcium phosphates. Clark and
Peech (1955) suggested the use of aluminum phosphate solubility
diagrams (or iron phosphate) for acid soils and show that ex-
perimental data fit these rather well.
Many of the heavy metals have quite insoluble hydroxides. It
would be expected that heavy applications of these metals would
result in saturation of adsorption sites and rapidly lead to
precipitation. Table 3 gives solubility products from some of the
compounds which might be expected to form in soils. Even though
these hydroxides are very insoluble, other even more insoluble
compounds may exist in soils. For example, zinc hydroxide would
give 3.2 ppm zinc in solution at a pH of 8.0. But Lindsay and Nor-
vell (1969) reported that less than 0.01 ppb Zn was actually found.
The form of zinc that is controlling this low solubility is not
known (Norvell and Lindsay, 1970).
CHEMICAL ALTERATION OF WASTE
The soil not only chemically filters but chemically alters
components of wastewater and sludge which it contacts. Thus,
to effectively understand the chemical filtration which will
occur, one must also consider the changes in chemical compounds
which will occur.
Wastewater and sludge materials contain many organic compounds.
These organic compounds may be adsorbed by clay materials in the
soil which will retard their microbiological breakdown. The nature
of clay-organic complexes and reactions has been reviewed by
59
-------
Table 3. Solubility Product Constants for Selected Compounds.
Chemical Formula Solubility Expression
Solubility Product
Constant
CdC03
CaC03
CoCOs
CuC03
PbC03
Hg2Cl2
A1(CH)3
Cd(OH)2
Cr(OH)3
Co(OH)2
Cu(OH)2
Fe(OH)3
Fe(OH)7
Pb(OH)2
Mg(OH)2
Hg(OH)2
Ni(OH)2
Mn(OH)2
Zn(OH)2
CaS04
CdS
CoS
CuS
PbS
MnS
HgS
NiS
ZnS
A T "nf\ . * T T f\
CdCOs = Cd++ +
CaC03 = Ca++ +
CoCOs = Co++ +
CuCOs = Cu++ +
PbC03 = Pb++ +
Hg2Cl2 = Hg2+ +
A1(OH)3=A1+^
Cd(OH)2 = Cd++
Cr(OH)3 = Cr+++
Co (OH) 2 = Co+
Cu(OH)2 = Cu++
F'e(OH)3 = Fe+++
Fe(OH)2 = Fe++
Pb(OH)2 = Pb++
Mg(OH)2 = Mg++
Hg(OH)2 = Hg++
Ni(OH)2 = Ni++
Mn(ON)2 « Mn++
Zn(OH)2 = Zn++
CaS04 = Ca++ +
CdS = Cd++ + S"
CoS = Co++ + S
CuS = Cu++ + S"
PbS = Pb++ + S"
MnS = Mn++ + S"
HgS = Hg++ + S"
NiS = Ni++ + S
ZnS = Zn++ + S"
A 1 TV\ . A 1 +3 i Tl
co3;;
co3- -
C03"
C03"
2C1"
+ 30H~
+ 20H"
+ 30H
+ 20H"
+ 20H"
+ 30H"
+ 20H
+ 20H"
+ 20H"
+ 20H"
+ 20H"
+ 20H"
+ 20H"
S04
5.2xlO"12
6.9xl0^3
8x10 ,,->
2.5xlO"(^
l.SxlO"1^
l.lxlO"14
5x10", ,,
2.0xio~3-:[
2, 5x10" ^
1.6x10^5
6X10 , r
2xio"^:
4xio";,
8. 9x10" if
3x10 Ifi
1.6x10"^
2xlO"f7
5x10" Ll
2. 4x10" 6
6x10" „
5xl°-36
4x10 ;J
4x10 S
8xl°-60
1x10 „
1x10 ~ii.
IxlO"20
T *1 f\
Ca4H(P04)3
Caio(P04)6(FH)2
Ca10(P04)6(OH)2
A1P04
FeP04 Fe+3 + P04"3
Ca4H(P04)3 = 4Ca2+ + H+ + 3P043"
Ca10.(P04) 6 (FH) 2 = 10Ca2++6P043-+2F"
Ca10(P04)g(OH)2 =10Ca2++6P043'+20H"
1x10
1x10
4x10
2x10
-26
-47
-119
-114
60
-------
Mortland (1970) and will not be covered here. Microorganisms will
decompose the organic materials with the release of carbon dioxide
and other simple compounds or ions. Organic nitrogen is released
during this process as ammonia or ammonium ions. Under well"
aerated conditions, this ammonia will be rapidly oxidize by
microorganisms to nitrate nitrogen. Both organic nitrogen and
ammonium will be retained in the soil to a large extent. But
nitrate nitrogen is susceptible to rapid leaching and would be
expected to rapidly move into groundwater or surface drainage,
whichever the case may be. Under proper conditions, nitrate nitrogen
will be denitrified and released back to the atmosphere in a gaseous
form. This requires that the nitrate nitrogen move into an
anaerobic zone with sufficient carbon as an energy source and the
correct microbial population. Although this occurs occasionally in
nature--in fact, denitrification is quite common in nature but only
occasionally are conditions correct for nearly total denitrification
of the nitrate present--the soil can be modified to favor this
reaction. Thus, Erickson et^al. (1971, 1972) produced a barriered
landscape water renovation system designed to optimize this reaction.
They reported more than 95% removal of nitrogen during the initial
stages of operation.
It should be pointed out that the total nitrogen content of waste-
water is usually sufficiently low that it is not likely to exceed
drinking water standards for nitrate content after passing through a
soil profile unless there is an input of nitrogen from another
source.
Oxidation-Reduction
Oxidation is defined as the loss of electrons and reduction as the
gain of electrons. When both oxidizing and reducing agents are
present in the same solution, the reaction will proceed until the rate
of oxidation is equal to the rate of reduction and no further net
change occurs.
If the following general reaction
aA + bB 1L mM
occurs in a reversible cell with e.m. f. equal to E, the free energy
change is Gr = NFE for the passage of N faradays. Making sub-
stitutions into the general form for the standard free energy of a
reaction yields:
E° - KT
nF (A)a(B?
61
-------
Although .theoretically the redox potential can be measured and
then the quantity of any species in solution as a function of pH
and redox calculated, in practice with soils and soil solution
this has not proven very successful. Bohn (1968) examined the
emf of gold, graphite, and platinum electrodes in soil suspensions
and concluded that gold and graphite were not useful. The platinum
electrodes responded to aeration conditions, but he could not de-
duce a quantitative significance of his measurements to the Nern-
stian distribution of oxidized and reduced species.
The oxidation-reduction status of many soils will likely
change under conditions of heavy application of wastewater and/or
sludge materials. Reducing conditions can occur rapidly and high
loading with organic materials will intensify reducing conditions.
Many chemical constituents will undergo chemical alteration
because of the change in oxidation status. The reduction of ni-
trate nitrogen has already been discussed. Patrick (1960),
in controlled redox experiments, found that nitrate nitrogen began
to disappear from his soil system for redox potentials less than
300 mv. The rate of disappearance increased with decreasing
redox potential so that 50 ppm nitrate nitrogen disappeared when
the redox Was -100 mv as compared to 20 ppm loss for a redox of
250 mv and no change for a redox of 300 mv.
Phosphorus will also respond to changes in redox. Patrick
(1964) reported that below 200 mv redox potential the extractable
phosphorus increased greatly. More than threefold increases in
extractable phosphorus were found when the redox was -200 mv
as compared to 200 mv. The sharp break in the phosphate re-
lease curve at 200 mv, the same point at which ferric iron begins
to be reduced, indicates that the conversion of phosphorus to an
extractable form is dependent upon the reduction of ferric compounds
"in the soil. Although limited data are available, it is expected
that soil under reducing conditions would not adsorb as much
phosphorus as the same soil in a well-aerated condition nor would
the level of phosphorus' in solution be maintained at as low as
level.
In addition to iron mentioned above, manganese will reduce
from plus four to plus two in soils with a low redox potential.
Bricker (1965) developed phase diagrams to predict manganous ion
levels as a function of pH and redox potential. But Bohn (1970)
found that soils with pH values less than 7.0 did not contain suf-
ficient manganese to yield the levels of manganese in solution
that were predicted.
62
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Effect of Wastewater Applications on Phosphorus
Most wastewater is expected to contain approximately 10 ppm
of total phosphorus. It is probably present in wastewater as
orthophosphate, condensed phosphates and organic forms. The latter
forms of phosphorus should degrade to orthophosphate rapidly in
soils if not in the preliminary wastewater treatment (Murrmann
and Koutz, 1972). Soils should rapidly adsorb phosphorus until
their adsorbing capacity is reached. Actually, as pointed out in
Table 2, not all of the adsorption capacity is expected to be
used at the levels of phosphorus in wastewater.
Phosphorus compounds can precipitate in the soil. Figure 1
illustrates the levels of phosphorus left in solution as a function
of pH. These values were arrived at by using solubility product
data from Table 3 and calculating total phosphate in solution
by use of the Debye-Huckel equation for estimating the activity
of the individual ion species in an ionic strength of 0.01 molar
calcium chloride solution. The activity of the calcium ion
was assumed to be 10"^-5y and it was assumed that gibbsite con-
trolled the aluminum solubility in soils (Lindsay and Moreno,
1960). It can be readily seen that the concentration of phosphorus
in solution in soils with a pH less than 6.0 is limited to low
levels. But the pH of most wastewaters will be above 7.0 which will
cause the soil pH to rise after continued application. For pH
values above 7.0, the solubility will be limited by a calcium
phosphate. Two compounds are shown in Figure 1, dicalcium
phosphate and octacalcium phosphate. It is expected that dicalcium
phosphate will form rapidly but it will limit phosphorus in solu-
tion to only 4 ppm at pH 9.0 and 8.0 ppm at pH 7.0. This would
effect a low percentage removal from wastewaters. Octacalcium
phosphates are slower to form. They have been found to form in
soils from a few weeks to several months. However, if they
form in the system they will limit the solubility of phosphates
to levels between .3 ppm at pH 8.0 and 2.7 ppm at pH 7.0.
Other calcium phosphates are much less soluble (i.e. hydroxapatite)
but form so slowly in soils that they are not expected to have
any effect on the precipitation of phosphorus from wastewater.
Effect of Wastewater Applications on Heavy Metals
If the soil pH is greater than 7.0, a condition expected after
prolonged wastewater application, most of the heavy metals will
precipitate as a hydroxide or a carbonate. Levels remaining in
solution are expected to be quite low.
Either natural or organic chelators would increase the level
of many of the heavy metals in solution. This can increase the
total concentration of heavy metals in solution by many fold.
63
-------
AIP04'2H20
Ca4H(P04)3-3H20
Fig. 1. Quantity of Total Phosphorus in Solution as a Function
of pH.
Although most of the heavy metals are expected to be retained
in the soil by adsorption onto clay surfaces or organic matter or
by precipitation, little is known about the effect of these heavy
metals on crop growth or quality. Melton, Doll and Ellis (1971)
found that even small applications of zinc to acid soils led to
excessive accumulation of zinc by bean plants and markedly reduced
yield. This would suggest that the effect of heavy metals on plant
growth should be carefully evaluated in wastewater disposal systems.
Sludge materials are many times extremely high in heavy metals
(Berrow and Webber, 1972). And, in addition, they may contain
64
-------
organic materials capable of chelating these heavy metals which
will result in increased uptake by plants and increased leaching
through the soil profile. Again, these factors must be carefully
considered.
REFERENCES
Arshad, M. A. and J. A. Carson. 1967. Ionic exchange behavior in
a. loam soil as indicated by movement of radio-calcium. Soil
Sci. Soc. Amer. Proc. 31, 321-324.
Aslying, H. C. 1954. The lime and phosphate potentials of soils,
the solubility and availability of phosphates. Royal Vet.
Agric. College Copenhagen, Yearbook, 1954, p. 1-50.
Aylmore, L. A. G., Mesbahul Karim, and J. P. Quirk. 1967. Ad-
sorption and desorption of sulfate ions by soil constituents.
Soil Sci. 103, 10-15.
Babcock, K. L. and R. K. Schulz. 1963. Effect of anions on the
sodium-calcium exchange in soils. Soil Sci. Soc. Amer* Proc.
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Barrow, N. J. 1967. Studies on the adsorption of sulfate by
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Barrow, N. J. 1970. Comparison of the adsorption of molybdate,
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Berrow, M. L. and J. Webber, 1972. Trace elements in sewage
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Biggar, J. W. and Milton Fireman. 1960. Boron adsorption and
release by soils. Soil Sci. Soc. Amer. Proc. 24, 115-120.
Blanchar, R. W. and Chun Wei Kao. 1972. Distribution and chemistry
of phosphorus in a Mexico soil after 82 years of phosphorus
fertilization. From M.S. Thesis of Chun Wei Kao (1971),
university of Missouri.
Bonn, H. L. 1968. Electromotive force of inert electrodes in soil
suspensions. Soil Sci. Soc. Amer. Proc. 32, 211-215. ~
Bonn, H. L. 1970. Comparisons of measured and theoretical Mn
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Bolt, G. H. and M. Peech. 1953. The application of the Gouy theory
to soil water systems. Soil Sci. Soc. Amer. Proc. 17, 210-213.
Bornemisza, E. and R. Llanos. 1967. Sulfate movement, adsorption,
and desorption is three Costa Rican soils. Soil Sci. Soc.
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Bower, C. A., G. Ogata, and J. M. Tucker. 1968. Sodium hazard
of irrigation waters as influenced by leaching fraction and
by precipitation or solution of calcium carbonate. Soil
Sci. 106, 29-34.
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DISCUSSION
Hunt: I wanted to ask a question on your anaerobic denitrifi-
cation. Have you had any problems in this particular
system with the clogging under anaerobic conditions,
and do you think that this concept has any applicability
to field conditions?
Ellis: In answer to your first question, yes, there has been
some trouble. Dick Thomas's slides fit exactly what we
70
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McKernan:
Ellis:
discovered. The trouble is in a very thin layer on
the surface. But you can manage this. You may have
difficulty in growing a crop on it. We're considering
quack grass since it seems to grow about everywhere.
But it does give us some difficulty. You can get away
from some of this by resting and it will go back into
receiving material. Secondly, you asked do I think it
has any applicability in the field, yes I do. The one
we have built is a very detailed system where ive have
it all enclosed in plastics. We don't lose anything
and we can analyze all the materials. Dr. Erickson in
our department says we can go about and build one of
these in the field very easily by using an asphalt
barrier to provide the anaerobic zone. We won't worry
about recycling all the water back through the swine
barn to flush it a second time, we'll just let it go
off into the ground water after it's all purified.
The one thing I expect trouble on though is the high
levels of salt, particularly potassium may give us
difficulties and perhaps also chloride.
I'm interested to know in your last experiment with the
swine barn waste whether the burms that you have con-
structed are characterized by certain kinds of vegeta-
tive cover and whether the evaporation characteristics
of the cover has affected your experiment?
We have operated these with grass covers and bare soils.
I would suppose that there has been some evapotranspi-
ration. I realize that in Michigan, our evapotranspi-
ration rates are not extremely high and we were putting
on more than 1 inch per day, so evapotranspiration
should not be a large part of this.
What method are you referring to when you mention ion
adsorption tests in the laboratory?
We've been using the Langmuir adsorption isotherm for
this. It's very simple to perform. You add increasing
increments of phosphorus to a series of 5 gram samples,
let them come to equilibrium...24 hours is sufficient
to do this, determine the amount of phosphorus adsorbed,
plug it back into the Langmuir equation and you can
predict the adsorption maximum plus the constant K.
This is what we're doing in the laboratory. There are
other isotherms that can be used, but I think more work
has been done with the Langmuir than anything else and
it at least appears to me to give us some hope of a
ballpark estimate. I certainly wouldn't want to stake
my reputation or life on the fact that these are accu-
rate but I think we're going with the best estimation
71
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we have right now without going out into the field
and measuring.
Sutherland: In your incubation treatment of soils with phosphate,
did you permit the soils to dry during that 3 month
period of time or were they allowed to remain moist?
Ellis: We maintained them relatively moist but we were doing
this in polyethylene bags and brought them back up to
field capacity about once a week during the 3 month
period, which meant there was some drying in the system.
This is something I haven't pursued as much as I should
have. It could be very critical to design criteria to
know how many times you could go through a cycle and
then give it 3 months in a field to recover. We know
nothing except that we were able to recover the origi-
nal absorption capacity in the laboratory once in a 3
month period.
Kraft: I have a question concerning the hog waste renovation
system. How long have you researched this and also
what was the type of soil? With the apparent nitrogen
removals that you got, are you sure that actual nitrifi-
cation and denitrification occurs or is it possible
that the ammonia is being absorbed by the soil and you
haven't saturated the absorption complex?
Ellis; We measured the ammonia on the soil and this will not
account for it. This is Erickson's experiment princi-
pally. I 'm the chemist involved in it and we do the
analysis work on it. I threw it in just as an illustra-
tion here, but let me say this. Yes, I think we're
getting rid of it by denitrification because when we
overloaded the system by accident one time, a switch
blew out and we dumped a weeks load in one night,
immediately the nitrate values went very high and we
no longer could handle it, so I think we are denitrify-
ing the system. We've been running it off and on a
little over a year now. How long we can go .with it I
don't know. Our soil microbiologist says indefinitely
providing we maintain the carbon there that we need for
the denitrification. If we lose the carbon it won't
work. As far as phosphate removal, we're on borrowed
time there and my calculations indicate that we should
go about 18 months before we start to leak phosphorus.
72
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THE SOIL AS A BIOLOGICAL FILTER
R. H. Miller
Department of Agronomy
The Ohio State University
Renewed interest in land disposal of secondary effluents and
liquid sewage sludges has stimulated the scientific community to
examine in more detail than ever before the physical, chemical,
and biological processes in soil which influence waste renova-
tion. In this symposium the useful analogy of "soil as a filter"
has been employed to simplify the discussion of the renovative
capacity of soil for waste materials. Previous papers by
R. E. Thomas, "Soil as a Physical Filter" and B. G. Ellis, "Soil
as a Chemical Filter" have covered the soil physical and chemical
properties which influence the "soil filter". This paper will
address itself to a third component of the soil filter, the
biological component.
The groups of organisms comprising the soil biological filter
are bacteria actinomycete, fungi, protozoa, algae, soil micro-
and macro-animals and higher plants. The significance of higher
plants to the successful renovation of liquid wastes on land has
been well documented previously (Kardos, 1967, 1970; Sopper, 1971)
and in this symposium. This discussion will therefore focus on
the contributions of the soil microbial population to the selecti-
vity and success of the soil filter.
THE MICROBIAL POPULATION OF THE SOIL FILTER
Individual groups of soil microorganisms in the plow layer
of agricultural soils often reach high numerical populations.
Estimates of 10? bacteria, 10^ actinomycetes, and 10$ fungi
per gram of soil are typical values obtained by plate counts on
various artificial media. Direct microscopic counts for soil
bacteria are usually higher with about 109 cells per gram of soil,
a common figure (Clark, 1967). Soil fungi become the dominant
numerical group of soil microorganisms in the litter layer (Ao)
and AI 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.
Addition of organic waste materials to soil should be expected
to and does increase microbial numbers (Glathe and Makawi, 1963;
Miller, 1972). Representative data for changes in various groups
73
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of microorganisms during the decomposition of an aerobically
digested sewage sludge are shown in Table 1 and 2.
Table 1. Plate Counts3 of Bacteria and Actinomycetes in Soils
Amended with Anaerobically Digested Sewage Sludge
after 1-Month Incubation
Soil
Ottokee
sand
Celina
silt loam
Paulding
clay
Soil ,
Moisture
FC
Sat
FC
Sat
FC
Sat
Organisms/g dry soil xlO"6
Control
7.5
7.0
15.5
30.5
28.6
13.7
90 ton/ha
33.0
472
268
864
484
37.9
224 ton/ha
46.0
867
88.0
.521
842
96.2
aOn soil extract-sludge extract agar.
FC = field capacity Sat = water saturation.
Table 2. Plate Counts of Fungi in Soils Amended with
Anaerobically Digested Sewage Sludge after 1-Month
Incubation
Organisms/g dry soil xlO
-4
Soil
Ottokee
sand
Celina
silt loam
Paulding
clay
Moisture
FC
Sat
FC
Sat
FC
Sat
Control
17.5
17.5
12.5
14.0
11.0
11.0
90 ton/ha
752
95
50
9.0
419
7.5
224 ton/ha
576
303
48
46
826
6.0
aOn rose-bengal-streptomycin agar.
FC = field capacity Sat = water saturation.
No data is presently available on population changes induced by
74
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irrigation with secondary effluent. Presumably the increase in
agricultural soils would be minimal because of the low organic
loading associated with secondary effluent. The changes which
might occur in the microbial population of forest soils remains
an unanswered question, but would probably be more dramatic than
in agricultural soils.
Numerous estimates of bacterial biomass and a few estimates of
fungal biomass have been calculated and representative data are
shown in Table 3. In most arable soils, the amount of bacterial
Table 3. Estimates of Microbial Biomass in Soilsa
Reference
Mean
Bacterial Biomass
g/m2
Ibs/Acre I of Soil Mass
Alexander
Jensen
Russell
Krasil'nikov
Latter §
Cragg
Stockli
Clark
(1961)
(1963)
(1950)
(1944)
(1967)
(1956)
(1967
33-330
100-1000
170-390
67-720
21-135
160-380
450
300-3000
900-9000
1500-3600
600-6400
190-1200
1500-3500
4100
0.015-0.15
0.045-0.45
0.077-0.18
0.031-0.33
0.010-0.06
0.075-0.17
0.22
300
2800
0.14
Fungal Biomass
Jackson
Clark "§
Paul
Alexander
(1965)
(1970)
(1961)
190
t.
260b
55-550
1700
2400
500-5000
0.09
0.19
.025-0.25
Values are calculated on live weight basis for 15 cm depth.
bg/m2/10 on depth.
biomass is commonly estimated to be somewhat less than that of fungi,
but to exceed that of the algae, protozoa and nemotodes combined
(Clark, 1967). Comparative data for the biomass of actinomycetes
are not available but is generally considered to be equal to that
of the true bacteria. Jenkison (1966) used the distribution of
75
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14c in soil after decomposition of 14c labeled ryegrass to estimate
that the soil biomass contained 2.3 to 3.5 percent of the soil
carbon.
In summary, the microbial component of the "soil filter"
occupies the upper portion of the soil profile (plow layer or
litter layer and AI horizon of a forest soil). Its mass makes
up only a relatively small part of the total soil mass. The
contribution of this small but significant component to waste
recycling and renovation will be discussed in more detail in
the paragraphs which follow.
SIGNIFICANCE OF THE BIOLOGICAL FILTER IN RECYCLING
MUNICIPAL WASTEWATER AND SLUDGE
Microbial Decomposition of Organic Wastes
One of the most significant functions of the microbial component
of the soil filter is the degradation of organic compounds contained
in the waste materials applied to soils. Indeed, one of the primary
advantages attributed to recycling of secondary effluent through
soil is that soil provides an alternative to stream discharge or
expensive tertiary treatments for reducing BOD and improving water
quality.
Disposal of liquid sewage sludges on land presents a somewhat
different problem since soil application is considered an economical
method for ultimate disposal of these high organic wastes. Proper
design and management of soils systems for sludge disposal by either
high rate single application or repeated lower rate applications
depends to a large part on the rate at which sludge organic matter
is decomposed. A less rapid decomposition of sewage sludges
would be advantageous for the reclamation of sandy soils or strip-
mine spoil. These soils would benefit from the improved physical
and chemical properties associated with organic matter accumulation.
In contrast, proper management of sludge disposal on finer textured
agricultural soils would require a more rapid rate of decomposition
of sludge carbon. Experience at both the Paris and Berlin sewage
farms indicate that organic matter accumulation was associated with
"exhausted" soils (Rohde, 1962). The primary reason cited for poorer
plant growth in these soils was an accumulation of toxic levels of
Cu and Zn associated with the organic matter. Excessive accumulation
of sludge organic matter might also reduce soil aeration and the
associated problems of odor, reduced root development, and mobility
of Fe and Mh.
Those of us in agriculture are well aware of the enzymatic
versatility of the hetertrophic microbial population of soil and its
76
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significance in decomposing a while host of natural and synthetic
organic compounds (Alexander, 1961; McLaren and Peterson, 1967).
Soil microorganisms are actually too efficient in their catabolic
activity and it has been found almost impossible to maintain the
organic matter of both mineral and organic soils when used for
agriculture, Hallam and Bartholomew (1953) concluded that annual
additions of organic carbon of 2 to 5 tons per acre were needed
just to maintain the organic carbon content of temperature region
soils.
The products of microbial metabolism of organic compounds
in soil under aerobic and anaerobic conditions are shown in the
generalized formulae below.
Aerobic
(CHO)n NS 2 fr 002+H20+ Microbial cells and Storage Products*
60%* 40%
NHl+ H?S+ Energy
^ JL
N0§ Sty
Anaerobic
(CHO) NS— ZfrCX^+Hz0* Microbial cells and Storage Products*
20% 5%
Organic Intermediates + Ofy + H2 + NH| + H2S + Energy
70% 5%
* The percentage values are estimates of the distribution of the
carbon of the orginal organic compound(s) after metabolism by
the microbial population.
While the main products of aerobic metabolism are C02, H20 and cells;
in the absence of 02 intermediate substances such as organic acids,
alcohols, amines, and mercaptans accumulate. Because the energy
yield during anaerobic fermentation is small, fewer microbial
cells accumulate_per unit of organic carbon degraded. Note also that
while N03 and SO^ are the end products of organic nitrogen and sulfur
compounds under aerobic conditions, IH^S and Mfy are formed under
anaerobic conditions.
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Secondary effluent from properly operating treatment plants
contains relatively low levels or organic compounds. A BOD of
25 mg/1 and a COD of 70 mg/1 was considered typical for
secondary effluent (Reed, 1972). Very little information is avail-
able on the chemical analysis of the organic compounds of secondary
effluent (Painter et al, 1961; Hunter, 1973). A portion of the
readily decomposable" organic materials (measurable by BOD) are derived
from sludge particles carried over from the treatment system.
These particulates should have a chemical composition similar to
that of microbial tissue. The data of Painter et al. (1961)
although accounting for less than 50 percent of~the effluent carbon,
would seem to verify this assumption. Part of the BOD of waste-
water effluent is also in the colloidal and soluble states and would
probably differ little from the analysis given for particulate
organic compounds. The protein, carbohydrates, nucleic acids,
fatty acids, amino sugars and other organic materials found within
microbial cells will be readily degradeable by the common bio-
chemical pathways of glycolysis, the tricarboxylic acid cycle,
B-oxidation, etc.
The remainder of the organic compounds of secondary effluent
are commonly called refractory organics. Refractory organics are
estimated by the difference between the values of COD and BOD.
As the name implies, these organic compounds are those which are
considered more slowly degradeable eg. phenols, detergents, fats
and waxes, hydrocarbons, cellulose, lignin, tannin, plant and bile
pigments, pesticides, and humic compounds. Physical entrapment
and chemical adsorption of these compounds in the soil matrix should
provide the necessary retention time for effective microbial de-
gradation of most of these compounds. Since some of these re-
fractory organics are considered toxic or problematic to different
sectors of our environment their elimination from the soil by
biodegradation will be discussed in greater detail in the next
section.
Very little information is currently available on the rate at
which the organic compounds of wastewater effluents are actually
decomposed in soil. Thomas and Bendixen (1969) studied the rate
of degradation of septic tank effluent in sand lysimeters and secon-
dary effluent in lysimeters of sand and a silt loam soil. About
80 percent of the organic carbon from septic tank effluent was
digested during 82-425 day dosing cycles with little difference
due to duration of dosing, temperature or loading rates. Only
68% of the organics of secondary effluent was degraded in the sand
lysimeters during 513 and 760 day dosing periods which 891 was
degraded during a 513 day dosing of a single lysimeter containing a
silt loam soil. One other aspect of these data is of significance.
An average of 14% of the applied organic carbon was found in the
percolate from the sand lysimeters (3 ft depth). These values are
very large and represent a potential problem with the renovating
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capability of the soil filter of coarse textured soils. These high
percolation rates of soluble organics may only reflect the influence
of continuous dosing and do not seem to reflect data from field
studies.
Application of secondary effluent to soil at a rate of 2"
per week for a 40-week period (March-November) should not place any
stress on the soil filter and the microorganisms of the "living
filter" should effectively remove and decompose most of the organic
material of the effluent. At a COD of 70 mg/1 the 80" addition
of effluent will add only 728 Kg (1600 Ibs) of organic matter per
acre. This is far below the maintenance level of 2 to 5 tons of
organic matter per acre per year noted by Hallam and Bartholomew
(1953) and there should be no accumulation of organic matter in
the soil. Higher and more frequent applications of secondary
effluent could cause waterlogging with concomitant anaerobic
conditions and slower rates of decomposition.
Anaerobically digested sewage sludges contain about 25% organic
carbon on a dry weight basis (Burd, 1968). During the process of
anaerobic digestion the waste organic solids are stabilized by the
almost complete microbial fexmentation of carbohydrates (the excep-
tion is cellulose) resulting in a 60 to 751 reduction in volatile
solids. Although data on the organic analysis of anaerobically
digested sludge is difficult to obtain the residual organic material
consists of a mixture of microbial tissue, lignin, cellulose, lipids,
organic nitrogen compounds, and humic acid like materials (McCoy,
1971).
As might be expected, anaerobically digested sludge is not
degraded rapidly in soil. A maximum of only 17 to 18 percent of
the sludge carbon was evolved as CO? during a 6-month period at
soil temperatures equivalent to spring-summer or summer-autumn in
Columbus, Ohio. It was apparent that the rate of sludge decomposi-
tion was more rapid during the initial month than during the sub-
sequent months following addition. These data certainly suggest
that addition of anaerobically digested sewage sludge to soils will
result in the accumulation of organic matter.
The above discussion dealt with the rate of degradation of
anaerobically digested sewage sludge. Undigested primary sludge or
activated sludge will contain organic residues which are much more
readily degradeable. Additions of the latter two sludges to soil,
at comparably high rates as anaerobically digested sewage sludge,
would exert a greater demand on the oxygen supplying power of soil.
Anaerobic conditions, odor and reducing conditions would probably
result.
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Elimination of Environmental Toxins
Municipal waste effluents and sewage sludges contain a number
of organic and inorganic substances which are considered potential
environmental toxins. Listed in this category are phenolic com-
pounds, the chlorinated hydrocarbon pesticides and chlorinated bi-
phenyls, detergent residues like ABS and NTA, petroleum products
and heavy metals.
One of the important questions which must be asked when
considering the feasibility of applying municipal wastes to land
is the fate of these chemicals after they reach the soil. The
primary environmental impact of these chemicals would occur if they
would move through or off the soil surface and reach ground and
surface water supplies. In this section we will discuss the partic-
ipation of the microbial component of the soil filter in removing
or detoxifying the organic toxins discussed above. The microbially
mediated reactions which influence the mobility or plant availability
of heavy metals will be discussed in the next section.
Phenols often reach sewage systems as wastes from oil re-
fineries, steel mills, and chemical companies (Reed, 1972; Lake Erie
Report, 1968). Secondary treatment is reported to reduce the con-
centration of phenolic compounds from 65 to 99 percent, the re-
duction being due to biological activity. The quantity of phenolic
compounds in secondary effluent used for land disposal can be ex-
pected to vary greatly. Data for a typical analysis of a secondary
effluent gives a value of 0.3 mg/1 of phenol (Rsed, 1972). Assuming
a 40-week period of irrigation (March-November) at 2 inches per
week only 6.2 Ibs/acre (6.9 Kg/ha of phenol) would reach the soil.
Even though the phenolic compounds are considered rather stable to
biological degradation considerable evidence indicates that
phenolic compounds should be decomposed in soils. The enxymatic
cleavage of the aromatic ring occurs by mixed function oxidases
followed by subsequent metabolism of the ring carbon (Dagley, 1967;
Gibson, 1968). A recent review by Horvath (1972) points out that
co-metabolism might be involved in the biological metabolism of
many organic compounds including some substituted phenolic
compounds. Regardless of the metabolis scheme, it is doubtful if
phenolic compounds will accumulate in soil when applied at or near
the normal rates. The microbial portion of the soil filter should
readily eliminate the phenolic compounds as long as physical and
chemical adsorption provide sufficient retention time for microbial
activity to proceed.
Pesticides, particularly the chloronated hydrocarbon insecti-
cides, DDT, aldrin, dieldrin, etc. and polychloroaromatic herbicides
such as 2,3,6-TBA and 2,4,5-T have received considerable publicity as
potential carcinogens or teratogenic agents. These same compounds
have acquired a reputation as being recalcitrant i.e.- nonbio-
degradable (Alexander, 1965a). Recent reports that these same
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pesticides may be metabolized to nontoxic inteimediates under
laboratory conditions by the process of co-metabolism offers a
possible approach to accelerating microbial detoxication (Horvath,
1972). It has also been suggested that "analog enrichment" which
involves the addition of a biodegradable analog at the same time
as the recalcitrant compound might result in a more rapid oxidation
and detoxication (Horvath, 1972). Data fram a lysimeter study by
Robeck et al. (1963) would seem to support the idea that co-
metabolism is indeed involved in the biodegradation of 2,4,5-T.
Although 2,4,5-T is normally considered to persist in soils for
periods of at least 6 months (Alexander, 1965b) data from this study
showed that 2,4,5-T added to septic tank effluent and percolated
through lysimeters was metabolized after a 14-day lag period. The
more rapid degradation of 2,4,5-T in the lysimeters may be due to
the organic materials of the effluent providing energy for the
microbial co-metabolism of this "recalcitrant" herbicide. All of
the pesticides discussed will normally be present in wastewaters
in significant quantity only as a result of industrial operations.
Initial low levels of pesticides coupled with strong adsorption
on soil particles and eventual biodegradation make it doubtful
if any environmental problems will occur.
Hydrocarbons in sewage effluents are derived from various
industrial sources and oil spills. An estimate of the maximum
quantity of hydrocarbons that will be present in secondary effluent
can be calculated on the assumption that more than 10 to 20 mg/
liter of petroleum in sewage will inhibit the microorganisms of
the activated sludge system (Reed, 1972). The activated sludge
process will remove between 50-70 percent of these hydrocarbons
leaving a maximum 6 to 10 mg/liter petroleum hydrocarbons in the
effluent. Hydrocarbons which reach the soil surface can be de-
graded slowly by a large number of soil microorganisms (Ellis and
Adams, 1961). In general, the low molecular weight hydrocarbons
decompose more rapidly than those of higher molecular weight and
Straight chained compounds at a rate branch chained aromatics.
-oxidation is the mechanism proposed for the microbial degradation
of aliphatic hydrocarbons and the involvement of mixed function
oxidases for metabolism of the aromatic hydrocarbons (McKenna
and Kallio, 1965). Strong adsorption on soil particles with
slow biodegradation should eliminate any problems with hydrocarbon
residues in soil.
The last group of organic environmental toxins which will be
discussed and which have caused some concern when present in effluents
are detergent residues. One infamous group of surface active agents,
the alkylbenzene sulfonates, (ABS) have been eliminated from use
in detergents since 1965 because of their slow biodegradeability.
Although ABS has been largely removed from detergent mixtures,
its biodegradeability in sewage systems and soils is still of
considerable interest. Studies by Robeck et aL, (1963) with sand
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and soil lysimeters and the Penn State group with field soils
(Kardos, 1967; Kardos et_al, 1968) have shown that ABS can be
effectively removed from waste effluents by the soil filter.
Both studies have shown that adsorption in the soil surface is
extremely important in providing the necessary retention time for
microbial activity to occur. The Penn State experiments recorded
70% reduction in ABS in the top few inches of the forest floor with
a 97% removal at the 4-foot depth. Cropland was even more effective
in removing ABS residues. Robeck e_t al. (1963) found that passage
of effluent through 3-foot lysimeters of sand were 85 to 96
percent effective in removing ABS. The importance of soil adsorp-
tion can be seen by their observation that a 21-day lag period
occurred before ABS was degraded by sewage and soil microorganisms.
The use of 35g ABS demonstrated that ABS was degraded to 35504
(76%) and short chain sulfonates (21%). Studies by Benarde
et al. (1965) and Horvath (1972) suggest that ABS may be degraded
By co-metabolism. This would certainly indicate the significance
of an organic matter rich soil or surface horizon for the rapid
decomposition of ABS.
The recent indictment of detergent phosphates as biostimu-
lants in aquatic systems has resulted in the use of alternative
compounds. Nitrilotriacetate (NTA) was one such alternative until
it too was removed from detergents pending further testing to
assure its safety in the environment. One aspect on which to base
the approval of NTA for detergent use is the ability of sewage and
soil microorganisms to degrade NTA. A recent study by Tiedje and
Mason (1971) using mono-carboxyl labeled NTA has shown that the
soil microflora can degrade NTA after a 2-4 day lag period. The
pattern and rate of degradation of NTA was variable among different
soils with no apparent correlation between degradation and soil
texture, drainage, plant cover, or pH. Degradation was, however,
dependent on aerobic conditions being maintained. Rapid degradation
of the tig, Ni, Mn, Co, Na, Cd, Pb, Cu, Fe, and Zn chelates of NTA
occurred in soils which previously had been exposed to NTA.
Elimination of Pathogenic Microorganisms
Land application of sewage, primary and secondary effluent or
liquid sewage sludges may present a potential health hazard because
of the human and animal pathogens which these wastes contain.
Among the common pathogens found in these waste materials are the
bacterial pathogens Salmonella, Shigella, Mycobacterium and Vibrio
comma; the hepatitis viruses, enterviruses and adenoviruses;~~and"
the protozoan, Endamoeba histolytica (Engelbrecht and Foster, 1973).
The potential health hazards associated with land disposal of
sanitary wastes without disinfection are associated with the
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pollution of groundwater by movement pathogenic microorganisms
through the soil filter, surface runoff carrying pathogens into
surface water supplied, contamination of leafy vegetables and root
crops with pathogens formed during irrigation. Of the four areas
listed above, the microbial component of the soil filter will be
of particular significance in the first two. Both the chance of
pathogens moving through the soil column into groundwater and
movement off the soil surface by runoff will depend in part on
their survival time in soil.
The initial soil reactions influencing the removal of pathogens
from liquid wastes are physical entrapment and chemical adsorption
by the soil, primarily at the soil surface (McGauhey and Krone,
1968). Once the microorganisms are retained the primary considera-
tion is the length of survival of these organisms in the soil matrix.
An extensive compilation of scientific literature has addressed
itself to the survival of pathogenic microorganisms in natural
environments including the soil (Van Donsel et. al, 1967; Law,
1968). Fortunately, most studies indicate a ratEer rapid die back
of coliforms and bacterial pathogens reaching the soil so that the
long term hazard to groundwater or surface waters are considered
minimal under normal conditions (McGauhey and Krone, 1967; Van
Donsel e_t al, 1967). A review by Rudolfs ejt al. (1950) cites
reports o£~~the survival of Salmonella for periods as long as 6
months to one year. Fecal streptococci from digested sewage sludge
have been found to survive up to 6 months in a clay soil but not in
a silt loam or sandy soil (Miller, 1972). Escherichia coli and
Aerobacter aerogenes have been reported to survive up to four years
in soil '(Mailman and Mack, 1961) .
Attempts have been made to ascertain the mechanisms by which
pathogenic and coliform microorganisms are eliminated from the soil.
Both abiotic and biotic factors have been considered significant.
Abioticf actors considered important to the persistence of pathogenic
microorganisms in soil are texture, moisture, pH, aeration,
temperature and organic matter content. This paper will not review
any of these aspects in detail, and readers are referred to the
following references for more information (Van Donsel et al, 1967;
Law, 1968, Rudolfs et al, (1950). The participation oFtEe" soil
microorganisms of tEe Trying filter in these processes would be
only indirect as microbial activity would alter soil pH, aeration,
and organic matter content. More important to our discussion
are the mechanisms by which soil microorganisms directly partici-
pate in the elimination of pathogenic microorganisms from the soil.
Rapid die back of pathogenic microorganisms in soil would seem
to be an example of a "homeostatic" reaction of the soil microbial
community which maintains the constancy of the community (Alexander,
1971a). An ecological explanation of this phenomenon is that all
of the potential niches are occupied in the complex environment of
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the soil so that the potential invaders find it difficult to gain
a foothold. The exact mechanisms involved in the elimination of
the foreign microorganisms eg. pathogenic bacteria, viruses and
protozoa from the soil environment are difficult to ascertain.
The possibilities included the production of microbial toxins;
enzymatic lysis; predatory protozoa; parasitic bacteria, fungi,
and phage; and the inability of the aleins to compete effectively
with the indigenous community for nutrients.
In summary, it seems likely that the soil filter will effec-
tively eliminate the pathogenic bacteria and protozoa reaching the
soil from applications of secondary effluent or sewage sludge.
Survival of viruses is still an open question because of the paucity
of information on this topic. The limiting factor in the elimina-
tion of all pathogens may be the effectiveness of the physical and
chemical processes of the soil filter in retaining the pathogens
long enough for their elimination by the soil microbial population.
Movement through coarse texture soils or surface cracks of fine
textured soils could certainly provide a means to circumvent the
effectiveness of the biological portion of the soil filter.
MICROBIAL REACTIONS WHICH INFLUENCE THE MOBILITY AND PLANT
AVAILABILITY OF IONS IN SOIL
Of the many problems which would limit the usefulness of land
disposal of municipal wastewaters and sludges, those involving
the accumulation and movement of N, P and various heavy metal ions
are potentially the most serious. For instance, movement of N or P
through soil or off the soil might accelerate the processes of
eutrophication in streams and lakes; accumulation of NOr-N at a
concentration greater than 10 mg/liter in ground or surface water
supplies may cause methemoglobinemia in children or nitrate
toxicity in animals; movement of potentially toxic or nuisance
levels of metal ions into groundwater may cause a deterioration of
water quality; and accumulation and increased solubility of heavy
metal ions in soil may cause phytotoxic effects and reduce the
renovation capacity of the' plant component of the soil filter. The
magnitude of the above problems should normally be greater with
liquid sewage sludges than with the more dilute secondary effluents.
It is the purpose of this section to discuss the influence of the
soil microbial population on the mobility and solubility of nutrient
and heavy metal ions in soil. The biochemical reactions of interest
are mineralization, immobilization, oxidation, reduction, chelation,
volatization, and precipitation.
Nitrogen - The microbial reactions involving nitrogen which
are of significance to the functioning of the "soil filter" are
mineralization, nitrification, and denitrification. Secondary
effluent contains rather modest concentrations of both NH^-N (9.8
mg/1) and NO^-N (8.2 mg/1) with a small amount of organic N primarily
84
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as protein (2.0 mg/1). The values given are typical values (Reed,
1972) and may differ considerably depending upon the efficiency and
retention time of the treatment system.
Because secondary effluent has a low C:N ration of <10:1,.a
net mineralization of nitrogen will occur in the soil. This
mineralized ammonium nitrogen as well as the ammonium nitrogen in
the effluent will be held by the soil exchange sites until nitri-
fied by the activity of the chemosynthetic autotrophs, Nitrosompnas
and Nitrobacter. Nitrification should proceed at a rapid rate in
all agricultural soils irrigated with secondary effluent at rates
which maintain aerobic conditions. The obvious exception will be
in those climatic regions where low winter temperatures will reduce
microbial activity. Nitrification of ammonium nitrogen reaching
acid forest soils may be limited by the absence of nitrifying
bacteria. It is possible that irrigation with waste effluents may
provide conditions which would allow a population of nitrifying
bacteria to develop.
Once formed, NO?; is very mobile and will be leached from the
soil as water moves through the profile. The factors affecting
nitrate movement in soils have recently received a great deal of
attention and will not be covered in this paper (Viets and Hageman,
1971). However, of considerable importance to the efficiency of
the total "soil filter" will be the adsorption and utilization of
N0§ by the actively growing agronomic crop or forest vegetation.
Studies at Perm State University (Kardos, 1967; Kardos et al, 1968)
have demonstrated the effectiveness of vegetation in removing efflu-
ent nitrogen from soil and maintaining the integrity of the soil
filter.
Activated sludge (avg 5.6% N) and digested sewage sludge
(avg 2.4% N) contain a considerable quantity of nitrogen (Burd,
1968) half of which is in the ammonium form. When sewage sludge
is applied to land for the purpose of disposal, there is a tendency
to apply as large a quantity of sludge as possible. A recent
U.S. Dept. of Interior report has recommended sludge application
rates of 10 to 40 tons of dry solids per acre which would contain
480 to 1920 Ibs of N per acre (Burd, 1968). Hinesly et al. (1971)
have proposed that no more than 2 inches of anaerobicaTly digested
sewage sludge be added to supply the nitrogen needs of a non-
leguminous crop. Even this rate of application supplies over 600
Ibs of N per acre. It is apparent from these reports that one
potential problem associated with disposal of liquid sludges on
land will be an excess of nitrogen above that which the growing
crop can assimilate. If nitrification of the excess ammonium
nitrogen originally present or subsequently mineralized occurs and
N0§ moves through the soil profile considerable nitrate enrichment
of groundwater or surface waters may occur. Lysimeter studies
(Hinesly et al, 1971) conducted on light silt loam soils by the
85
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University of Illinois have shown that nitrification does occur in
soil amended with from 5 to 10 inches (1650-3000 Ibs of N/acre)
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 commercial
fertilizer. The significance of the plant cover in nitrogen reno-
vation was shown by the fact that no water and accompanying nitrate
moved through the 4- feet lysimeters during the summer months. It
should be readily apparent from these studies that the soil filter
is permeable to high applications of nitrogen in liquid wastes.
The preceding discussion has emphasized one of the more
critical problems associated with the microbial component of the
soil filter, namely nitrification. It is perhaps fortunate that
a second microbial reaction associated with nitrogen, biological
denitrification is potentially useful in alleviating the potential
pollution hazard associated with the formation and movement of NOj .
Biological denitrification involves the loss of N2 and
during anaerobic respiration in which NO^ is used as an electron
acceptor. The microorganisms involved are primarily facultative
anaerobic heterotrophic bacteria. Conditions which favor biological
denitrification would include a near neutral pH, a readily available
source of carbonaceous substrate, and anaerobic conditions
(Eh * +200MV) .
The significance of biological denitrification during disposal
of wastes on land is difficult to evaluate. Undoubtedly applications
of secondary effluents to agricultural land, regardless of the mode
of application, should provide at least temporary periods of anaero-
biosis and sufficient substrate for some loss of nitrogen to the
atmosphere. This will be true even though proper management of soils
for wastewater disposal require that aerobic conditions are main-
tained. The reason for this apparent anomaly is anaerobic microsites
can occur in soils considered aerobic (Broadbent, 1973).
Denitrification losses from soils which have been amended with
liquid sewage sludges should exceed that from secondary effluents
because of the organic matter supplied. This author is not familiar,
however, with any quantitative evaluation of denitrification from
sludge amended soils.
In conclusion, it seems apparent that biological denitrification
will remove some NOj from soils during waste renovation on agricul-
ture soils. If the pH of forest soils will allow a build-up of
nitrifying bacteria with subsequent nitrification, it is also likely
that the heterotrophic denitrifying bacterialwill also be present.
It is doubtful that much can be done to increase biological denitri-
fication on spray irrigation sites where growing crops are being
maintained. Rapid infiltration systems such as that at Flushing
86
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Meadows (Bouwer, 1973) and the overland flow systems for waste
disposal should be able to take greater advantage of denitrifica-
tion for NOj removal.
Phosphorus - Phosphorus will be present in secondary effluent
(10 mg/1) primarily as orthophosphate; as the condensed phosphates,
meta and polyphosphates; and as organic phosphate (Reed, 1972).
Sewage sludges contain high concentrations of phosphorus (0.7 -
3.91) (Burd, 1968). Although the chemical identity of sludge
phosphorus has not been determined, it probably corresponds closely
to that of secondary effluent.
Chemical fixation of orthophosphate by Fe, Al, Ca, and clay
minerals in soil and plant removal provide the primary mechanisms
for the renovation of waste phosphorus by the soil filter. Soil
microorganisms influence the effectiveness of soil renovation
primarily by mineralizing orthophosphorus from the more mobile
organic and condensed phosphates so that the fixation reactions
can occur. The significance of the microbial reduction of ortho P
to volatile PH3 and the synthesis of inorganic poly P in soils
(Ghonsikar and Miller, 1973) has presently not been evaluated.
Sulfur - The primary chemical forms of sulfur in secondary
effluent will be 804 with small amounts as organic sulfur. Sewage
sludges will be higher in organic sulfur but will also contain
some insoluble metal sulfides and hydrogen sulfide. If aerobic
conditions are maintained in the soil during waste disposal the
microbial reactions of primary interest are the oxidation of metal
sulfides and H2S to S0| which is both mobile and available to
higher plants. Mineralization of organic sulfur will probably be
of greater significance than immobilization when waste materials
are added to soils with the result that the pool of soluble S0|
will increase.
Improper management of liquid waste disposal on land which
creates anaerobic soil conditions will result in S0| reduction to
H2S. Hydrogen sulfide can in turn react with various metal ions
to form insoluble sulfides. Ferrous sulfide has been implicated
as one of the chemical components responsible for intensifying soil
clogging during wastewater irrigation (Reed, 1972).
Inorganic ions - Waste effluents contain relatively low
concentrations and sewage sludges high concentrations of metallic
and non-metallic cations and anions (Ewing and Dick, 1970;
Lagerwerff, 1967). The exact composition of these waste with
regards to inorganic constituents is extremely variable and
dependent upon the industrial sources which contribute wastes
to the sanitary treatment system as well as the treatment pro-
cesses itself.
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When secondary effluents are applied to soils most of the
heavy metals are retained within the surface horizon by inter-
actions with soil organic matter and colloidal clay minerals; or
by precipitation as insoluble oxides, hydroxides, phosphates, or
sulfides. In the case of applied sewage sludge, the sludge solids
will retain most of the metal ions until released by the microbial
decomposition of the sludge organic matter.
Addition of these inorganic constituents to soils in liquid
wastes presents a potential problem because of their movement into
groundwater, destroying water quality; or by their accumulation to
phytotoxic levels in the soil. The latter effect would reduce the
efficiency of the higher plant component of the "soil filter" for
waste renovation. In addition a particular element may be taken
up in such concentration that the intended use of the harvested
plant material for human or animal consumption may be curtailed.
Soil reactions of iron and manganese are similar in many ways
and thus will be discussed together. A detailed discussion of the
relative significance of each reaction to the mobility of Fe and Mn
is beyond the scope of this paper, but a few salient remarks will
be made about each. The readers are referred to an excellent
symposium Mortvedt et al. (1972) for further information on the
soil reactions of tEese and other micronutrient ions. Unfortunately,
much of this information is based on soil reactions at low concen-
trations of inorganic ions. Considerably more information is needed
on the interactions of inorganic ions in soils at the high concen-
trations likely to be encountered after prolonged applications of
waste effluents and sewage sludges.
The iron and manganese in well aerated soils and at near
neutral pH's will be primarily found in the oxidized state as
insoluble organic matter complexes and insoluble oxides, hydroxides,
and phosphates. The concentration of these individual ions in the
aqueous phase is normally very low, often in the parts per billion
range. The ions which are found are considered to be primarily in
organic combination as soluble metal-organic matter complexes
(Lindsay, 1972; Geering e_t al, 1969). Organic compounds capable of
forming chelates are continuously being produced in soil by microbial
activity. Most of these compounds can in turn be decomposed so the
amount present in the soil solution represents a balance between
synthesis and destruction. Since chelating agents have the ability
to transform solid phase forms of Fe and Mn (hydroxides, phosphates,
etc.) into soluble metal complexes, their production during decay of
organic waste materials are likely to increase the availability of
these ions to plants, and their mobility through the profile. The
degradation of the soluble organic matter-metal complexes, as well
as the insoluble organic matter complexes will again release Fe and
MN ions which will again be precipitated or recomplexed. Some
microorganisms can also form mineral acids (nitric and sulfuric)
which would solubilize some of the oxides, hydroxides, or phosphates),
-------
Another microbial process of considerable significance to the
mobility of Fe and Mn is that of reduction. If a soil becomes water-
logged during irrigation with liquid wastes the Fe2+ and Mn2+ level
in soil rises rapidly. Ferrous and manganous ions are highly mobile
in soil and may, under prolonged anaerobic condition, move through
the soil profile into water supplies or form a water impermeable
layer in the B horizon (Boring, 1960; Bocho, J. , 1965). The presence
of available organic substrates enhances the reduction of both ions.
The reduction of Fe3+ has been shown to be entirely a result of micro-
bial activity, while Mn^+ reduction is almost exclusively microbial
at a pH >6.0 (Alexander, 1961). The reduction of both ions may occur
as an indirect result of microbial activity in lowering soil pH, or
of the Eh by depletion of 63; or by direct reduction with both Fe3+
and Mn+ serving as electron acceptors in cell respiration. Bio
logical reoxidation of both Fe2+ and Mn2+ has been shown to occur in
soils (Aristovskaya and Zavarazin, 1971; Ehrlich, 1971) although
chemical oxidation of Fe2+ can occur at a near neutral pH, and Mn2+
at a pH >8.0.
Under anaerobic conditions and in the presence of high concen-
trations of H2S, insoluble sulfides of both Fe and Mn can be formed
in soil (see section on sulfur). The effect of sulfide formation
will be to reduce the mobility of Fe and Mn.
The microbial reactions which influence various heavy metals
ions are like those of Fe and Mn but do not include oxidation-
reduction reactions. As with Fe and Mn a very large percentage of
the ion present in solution probably occurs as soluble organic
complexes (Lindsay, 1972) . The quantity of all of these heavy metals
which will be retained by the "soil filter" after repeated applica-
tion of metal containing wastes will be largely related to the organic
matter content of the soil. Unfortunately very little is known
concerning the relative amounts of the various metal ions which will
occur as organic-metal complexes or of the factors affecting the
availability of the organically bound nutrients to plants. Experi-
ences at the Paris and Berlin sewage farms have indicated that
"exhausted" soils high in organic matter retained a larger total
amount as well as soluble Cu and Zn (Rohde , 1962) . Studies at the
University of Illinois by Hinesly et al. (1971) have shown that
plants grown in soil amended with TTquid digested sewage sludge
contained a greater concentration of Zn, Mn and Fe but not Ni and Cu.
They attributed the enhanced uptake in part to the addition of the
elements in the sludge as well as the indirect effect of sludge on
increasing the availability of the metal ions.
A third group of inorganic ions K+, Mg , Ca , and Na are
also found in waste effluents and sewage sludges. None of these
cations are complexed strongly by soil organic matter and their
retention in soil is related to normal exchange reactions on clay
minerals and organic colloids. The microbial population of soils
has little effect on the reactions of these ions except indirectly
in the formation and degradation of soil organic matter.
89
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A couple of other microbial reactions could possibly influence
the mobility of metal ions in soils. One involves the alkylation
of certain metals to volatile derivatives. Thus far, the microbial
alkylation of Hg, Se, Te, and As has been demonstrated to occur
(Alexander, 1971b; Ehrlich, 1971). Whether these laboratory phe-
nomena have any significance in the soil environment remains to be
evaluated. A second reaction would be the immobilization of metal
ions within microbial cells. Although there are some examples of
very large accumulations of metal ions within microbial cells in
culture, it is doubtful if this reaction will be of any significance
in the soil reactions of metal ions.
CONCLUSIONS
The preceding discussion has reviewed in moderate detail the
various microbial reactions which influence the success of soil as
a filter for renovating municipal wastewater and sludge. The
.majority of these activities are beneficial, actually essential,
for maintaining the integrity and effectiveness of the soil filter.
Only one reaction, nitrification, can be considered detrimental to
the success of the soil filter when the disposal method maintains
adequate soil aeration.
It should also be emphasized that prolonged periods of
anaerobiosis must be avoided for the proper functioning of the
microbial component of "the soil filter. Proper management of land
disposal systems for liquid waste regardless of the mode of
application must provide for periods of adequate aeration. Failure
to do so will result in reduced decomposition of organic wastes,
odors, reduction and mobilization of Fe and Mn, changes in the
solubility of other inorganic ions, and inundation of vegetative
cover. In addition, anaerobic conditions in the soil seem to
intensify the clogging of the soil surface with microbial cells,
polysaccharides, and ferrous and manganous sulfides which reduces
water infiltration.
90
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SITE SELECTION CRITERIA FOR WASTEWATER
DISPOSAL — SOILS AND HYDROGEOLOGIC CONSIDERATIONS
Richard R. Parizek
Department of Geosciences and The Mineral Conservation Section
The Pennsylvania State University
Site selection criteria for sewage effluent spray irrigation
sites are discussed. Soils, geology, hydrology, topography, project
management and other factors are considered to maximize the chances
for achieving a high degree of renovation of waste constituents
while at the same time minimizing secondary environmental problems
that can result such as -- degradation of groundwater quality,
water logging of soils, surface runoff and erosion, and local flood-
ing. Site conditions suitable and unsuitable for groundwater
recharge and reuse are pointed out as are factors to be considered
when designing monitoring programs necessary to prove the degree of
treatment being achieved, hence the success or failure of a particu-
lar irrigation operation. Finally, the importance of the hydro-
geologic-soil condition is discussed for the benefit of administrators
who are responsible for defining environmental policy and preparing
guidelines for design, regulation and enforcement procedures to be
used for wastewater irrigation projects.
Comments are not based solely on experiences gained with the
Penn State Wastewater Project. Rather, basic principles are
considered which should apply when selecting irrigation sites or
designing and operating irrigation systems in many areas. Experiences
from our own project as well as other successful and unsuccessful
projects in Pennsylvania and elsewhere are used for illustration.
SIGNIFICANCE OF THE SOILS, GEOLOGIC, AND HYDROLOGIC CONDITIONS
Significance of various physical and geochemical factors to be
considered when selecting irrigation sites vary depending on the
quality of wastewater to be applied, acreage required, amount and
duration of wastewater application, water quality standards to be met
for the receiving body of water, climate, other uses to be made of
the irrigation site, seasons of year water is to be applied, atten-
tion that is likely to be given to managing the irrigation project,
and a number of other factors.
For example, where effluent is being used primarily as a source
of irrigation water and is being applied solely as a benefit to
crops, the amount and quality of water best suited to plant growth
and the intended use of the crop may be the limiting factors. How
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often and how much water should be applied and by what method to
achieve the best growth response at least cost? Almost any soil
and cover crop condition can beneficiate sewage effluent when
application rates are equal to or less than evapotranspiration
rates because under these conditions little if any effluent moves
through the soil. The soil moisture reservoir becomes a physical
barrier to water movement whenever the soil-water content drops below
field capacity. The residence time of effluent in the biologically
active zone is prolonged in such a climatic setting and effluent is
depleted mainly by evapotranspiration rather than deep percolation.
In more humid regions this procedure would be impractical because
water could be applied only from time to time as weather conditions
dictate. More frequent applications would be possible in arid to
semi-arid regions.
Prolonged use of this practice in more arid regions, balancing
application rates with evapotranspiration rates, however, would
result in a salt or total dissolved solids build-up in shallow soils,
an increase in the salinity of return flow and occasional groundwater
recharge of poor quality. This normally would not be a problem in
humid regions because precipitation is available to provide dilution.
When planning to apply wastewater in arid to semi-arid regions,
considerable attention must be given to site selection and land
management to be assured that the irrigation area will not be chem-
ically degraded and the agricultural productivity destroyed. A
considerable experience has been gained in applying waters with a
high total dissolved solids content in arid and semi-arid regions
with both favorable and devastating results. This general problem
has been studied by others and is well documented in the literature.
For example, Fireman and Heywood (1955). Several points are obvious.
Application rates combined with precipitation must exceed evapotrans-
piration rates to insure that soluble salts are leached from the
soil. Good subsurface drainage is desirable as is a rather deep
water table to minimize groundwater evapotranspiration losses and a
resulting salinity build-up. There is a limit particularly for large
projects to how many times reclaimed effluent should be recycled from
the community to the treatment site to avoid a long term increase in
total dissolved solids. It is desirable to have thorough drainage
of return flow or an open rather than a closed geochemical system.
In the latter, the total dissolved solids will accumulate and ulti-
mately may cause problems.
Most wastewater irrigation projects will not be operated only
when irrigation water is required. Rather, to be feasible, they must
operate during periods when soil moisture is in excess of plant
requirements, and the moisture content is at or above field capacity.
The more irrigation rates exceed evapotranspiration rates the more
important topography, soils, geologic, hydrologic and other factors
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become in the selection of irrigation sites to insure sufficient and
long-termed renovation of waste constituents. No one of a number of
factors to be considered under these circumstances needs to be
limiting or controlling but rather these factors must be considered
together.
Other authors in these proceedings have stressed the role and
importance of biological, chemical and physical processes in waste-
water renovation which must work in tandem to provide a maximum
degree of renovation. The basic processes involved are summarized
in Table 1. These processes operate primarily within the biolog-
ically active zone of shallow soils and in deeper soils and rock
above and below the water table. The soil and rock substrate and
the soil-water and groundwater they contain serve more than just as
a substrate for the biological community--the living filter which
accounts for most of the renovation achieved. Rather they exert
an active physical and geochemical role as well which helps to
increase the efficiency of the treatment system and provide protec-
tion or a factor of safety against the premature or eventual break-
through of waste constituents to the groundwater or surface water
reservoir. This can occur during prolonged use of irrigation sites,
during periods of excessive application accompanying pipe line
breaks or leaks, where runoff and local ponding at the surface and
in the subsurface redistributes effluent and causes heavy loadings,
during heavy precipitation, during winter irrigation, and melting
of snow and ice packs.
It is desirable, therefore, in site selection studies to con-
sider those aspects of the soils, geologic and hydrologic condition
that will help to maximize and prolong the renovation process,
hopefully, indefinitely.
Characteristics of an Ideal Site
There is little point in defining site characteristics so
specifically and rigidly that they can rarely be met under the great
variety of conditions likely to be encountered in the field. It is
desirable to outline conditions that should be strived for when
selecting wastewater renovation sites. The very best and most con-
servative sites should always be selected when choices are available.
In this manner secondary environmental problems can be minimized or
eliminated and the life of the renovation system, hence the project,
prolonged indefinitely. Fewer choices are available for small
projects where effluent must be treated close to its source. If
site conditions are poor at these locations, land application may
not be the answer. For larger projects where millions to tens of
millions of gallons of effluent a day are involved, proximity to
the source is far less important than obtaining a suitable site.
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TABLE 1. Summary of Physical, Geochemical and Biochemical Processes
that Contribute to the Renovation of Solid and Liquid
Waste Materials (After Parizek and Langmuir, 1971)
Physical Processes
Filtration
Dispersion
Dilution
Adsorption-desorption
Gas transfer
Geochemical Processes
Complex ion pair formation
Acid-base reactions
Inorganic redox reactions
Ion exchange
Precipitation-solution
Biochemical Processes
Solute uptake in biosynthesis
Solubilization of cellulose, etc.
Mineralization of organics
Catalysis of inorganic redox reactions
It is equally important that regulatory officials responsible
for adopting policy guidelines for irrigation projects or for review-
ing, approving and policing irrigation projects maintain a flexible
viewpoint as well because many sites that may appear to depart
drastically from the ideal may in fact be found to be suitable under
actual use. For example, poorly drained soils may actually provide
a higher degree of nitrate removal when compared to better drained
soils. Control of nitrate concentrations in groundwater at irriga-
tion sites is one of the main challenges that users of the irrigation
system face. Nitrate removal can be one of the weakest links in the
irrigation concept.
It is possible to engineer some sites to improve infiltration
and drainage, improve renovation, control groundwater levels, prevent
trespass of wastewater by overland or subsurface flow, control wind
drift of effluent, etc. Regulatory officials should encourage in-
novation and originality among those designing and operating irriga-
tion projects because each project must be designed as a separate
unit and each will have its own special problems and challenges that
must be worked out. There is no single fixed blue print for waste-
water irrigation systems that can be used under all field
circumstances.
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Infiltration and Drainage
Sewage effluent must infiltrate into soil and be retained for
a sufficient period within the biologically active zone to be acted
upon by renovation agents. Some renovation may be achieved during
overland flow but this is not as effective as when effluent enters
and is retained within the soil. Reduction in BOD, removal or
reduction of suspended solids and bacteria, etc. can be expected
during overland flow. After infiltrating into the soil, some of
the effluent may be withdrawn and consumed by evapotranspiration,
some may percolate to the water table or move laterally as interflow
and be returned to surface. Lateral flow need not be bad at irriga-
tion sites provided that the effluent has been renovated prior to
being discharged to the surface and provided that other wastewater
is not being applied to these soil-water discharge areas, particu-
larly the larger ones. Some lateral flow is inevitable particularly
when effluent is being applied in humid regions, on sloping ground
.or on soils where the B-horizon, caliche layers, plow soles and
stratification within or below the C-horizon help promote lateral
movement. Effluent has been sampled at the Penn State research
facility after having moved laterally through soil for 25 to more
than 250 feet before being discharged to the surface or intercepted
in a 17-foot deep trench lysimeter. Water was found to be of
favorable quality wherever it had entered the soil and had a resi-
dence time sufficiently long to permit renovation.
Natural soil or at least fine-grained unconsolidated material
is always preferred at irrigation sites over mechanically weathered
bedrock, quarry wastes, artificial fills containing a wide variety
of waste materials and grain sizes. The latter can have high or
excessive infiltration capacities and may be too well drained to
favor renovation when compared to most natural soils. A moderately
well drained to well drained soil would appear to meet both infil-
tration and drainage requirements for an irrigation area. However,
even less well drained soils can be considered provided that efflu-
ent is not being applied during prolonged rainy periods, periods of
heavy rainfall or freezing weather.
Values of hydraulic conductivity of different soils have been
reported by O'Neil (1949), and Smith and Browning (1946). These
may serve as a guide when considering soils for irrigation projects
(Table 2).
Soils in the extremely slow to very slow class are bound to
create water logging and runoff problems at irrigation sites and
neither can be drained effectively to control the water table posi-
tion. Soils in the slow class may require artificial drainage to
control water levels, and improve on aeration conditions. These
soils may prove to afford better nitrate removal when compared with
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TABLE 2. Classes of Permeability or Percolation Rates for Saturated
Sub-soils (Expanded from Smith and Browning, 1946)
Class
Hydraulic Conductivity
or Percolation Rate
inches/hour
Comments
Extremely
slow
Very slow
Slow
Moderate
Rapid
<0.001
0.001- 0.01
0.01 - 0.1
0.01 - 1.0
1 -10
Very rapid
So nearly impervious that leaching
process is insignificant. Unsuit-
able for wastewater renovation
under most circumstances.
Poor drainage results in staining;
too slow for artificial drainage.
Wastewater renovation possible
under restricted conditions.
Too slow for favorable air-water
relations and for deep root devel-
opment. Usable under controlled
conditions; drainage facilities
may be required; runoff likely to
be a problem. Good nitrate removal
possible.
Adequate permeability (conductivity)
Ideal for most irrigation systems.
Excellent waterholding relations
as well as excellent permeability
(conductivity). Ideal for most
irrigation systems. Application
rates may have to be reduced to
insure renovation.
Associated with poor waterholding
conditions. Infiltration and
drainage may be too rapid to achieve
complete renovation. Extreme cau-
tion required.
better drained soils. Soils in the moderate to rapid class should
be ideal. For soils in the very rapid class, flow rates may be
excessive thus precluding a high degree of renovation. Effluent must
be retained within the soil profile and subsoil for a sufficient
period to allow the renovation processes to be effective. This is
measured in days, not hours and will vary with climate, season of
year, crop cover, etc.
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At our winter irrigation site, for example, a 6-inch per week
application rate (water applied during a single day) was not ex-
cessive from an infiltration standpoint. However, nitrates and MBAS
were rapidly driven to depths of 17 feet in the soil after six
months of winter irrigation and were below the biological zone and
could not be renovated during the following growing season by bio-
logical processes. These constituents were free to migrate to the
water table after adsorption requirements were met.
Where highly permeable sand and gravel, mechanically weathered
bedrock, fractured bedrock, conduits and cavity systems are present
beneath the soil, little if any additional treatment except dilution
and dispersion should be anticipated. Renovation must be achieved
within the overlying soil.
Irrigation techniques and equipment are so well advanced today
that it is possible to select and achieve a 1/4-, 1/6-, 1/8-inch or
even lower application rate per hour. Where, for example, a 2-inch
per week amount is called for, it is possible to apply the water at
a low rate over a one to two day period or at a higher rate for
briefer periods but on two separate days following one or two days
of rest. Many sites with poorly drained soils could be considered
suitable for irrigation provided that application rates are lower
than for well drained soils assuming all other factors were equal.
The infiltration capacity can be maintained or improved by
adopting good farm management practices at the irrigation site. If
effluent is to be applied in winter or on soils with low infiltra-
tion rates, plowed ground should be avoided. Rather, forested areas
or hay fields with well established cover crops should be used.
Even under favorable site conditions, local runoff is possible from
time to time particularly in the winter, early spring or late fall
when evapotranspiration requirements are low, soil-water contents
are high, water temperatures are low, and effluent is applied during
periods of precipitation.
When winter irrigation is required in northern latitudes,
careful attention must be given to selecting irrigation sites that
have good infiltration capacities and subsurface drainage. Forested
areas are desirable. Root holes, animal burrows and thick organic
litter on the forest floor tend to provide higher infiltration
capacities when compared to the same soil type in adjacent grasslands
or cultivated areas. Also it has been shown that a honeycomb-type
frost structure or more open structure tends to form in forested
areas compared to the less permeable concrete-type frost that develops
in plowed ground (Storey, 1955).
At the Penn State site runoff from melting snow and ice packs
composed of effluent is more pronounced in open fields than from ice
pac
cs in woodlands having the same soil type. Runoff may be traced
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across sloping, hayfields for 100 to more than 500 feet to where it
enters forest border lands that surround our fields. Here it is
lost by infiltration within 500 to 1,000 feet from the irrigation
plots even during periods of quick thaw.
Runoff from the Penn State irrigation plots is less than might
be expected for other facilities because closed surface sags and
depressions reflecting the differential solution of underlying
dolomite bedrock provide surface detention storage in fields and
forests alike. These depressions trap surface water, minimize
runoff, and help to promote infiltration.
Measurement of Infiltration
The infiltration process is complex and influenced by a number
of variables. The problem is to assess the infiltration rate not
at isolated test plots, within the area of interest, but rather for
the entire project area. This is a difficult task in advance of
irrigation because test plots that have adequate infiltration char-
acteristics when tested by themselves may in fact prove to be soil-
water or even groundwater discharge areas or become waterlogged after
water is applied to a more general area for prolonged periods. It
is as important to know how the proposed site behaves in the presence
of excess water in advance of irrigation - as in the Spring - as it
is to know the infiltration capacity at a number of test plots.
Potential drainage problem areas need not be obvious when observing
soil characteristics or type of vegetation present. Frequently
problem areas can be isolated by field study following spring thaws,
prolonged periods of heavy rainfall and recharge. Runoff, standing
water and near saturation conditions may be observed for brief
periods at sites where drainage problems are likely to occur after
.extensive irrigation begins.
Even experiences gained with normal agricultural irrigation
practices may not prove to be foolproof in selecting irrigation sites
and isolating problem areas. Normally, water is applied when there
is a moisture deficit, hence, potential drainage problem areas are
not as likely to be revealed. Wastewater treatment by irrigation
normally requires that Water be supplied in excess of evapotranspir-
ation requirements and during periods of excess water even if winter
storage is planned. Infiltration and drainage problems are maximized
under these circumstances.
Infiltrometers either of the flooding or sprinkler type may be
used to evaluate infiltration rates at test plots with the reserva-
tions mentioned. Methods involved have been described by Chow (1964),
Gray, Norum and Wigham (1970) and others. Parizek and Myer (1968)
pointed out that preliminary estimates of drainage problems can be
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obtained from experience or by conducting trial irrigation operations
on site using potable water. Areas with poorest drainage might be
tested at rates in excess of what is planned during normal operation
to determine the worst possible drainage conditions that might result.
Problem areas can be avoided in the final design of the distribution
lines, receive less water on a weekly basis, be used only seasonally,
or drained artificially. Even then, it may be difficult to antici-
pate subsurface drainage conditions that may develop in the long
term within deeper soil or rock both above or below the water table.
For these reasons, all irrigation projects should undergo a
shakedown period when they are first put into operation. During
this time problem areas can be isolated and necessary adjustments
made in the irrigation system. This may require changing the appli-
cation schedule. Spray heads may have to be removed, or even segments
of distribution lines discontinued at troublesome areas. If correc-
tive action is taken, many of the drainage problems usually observed
at irrigation sites can be minimized or eliminated. Unfortunately,
irrigation systems are often viewed as rigid systems that once
designed and constructed, no longer need to be altered. Economic
and poor enforcement considerations dictate this to be so.
At our Gamelands site for example, effluent was applied on hill
slopes underlain by stratified soils comprised of interbedded clay,
silt and sand. Lateral flow and surface discharge was excessive at
4-inch and 6-inch per week winter application rates when effluent
was applied from line to line in sequence going from top to bottom
or bottom to top of a particular slope. Surface discharge and run-
off were reduced when lower application amounts were used (decreasing
from 6 inches to 4 inches per week) and when effluent was applied in
a staggered manner, i.e., first using a line on one slope, then a
line on an adjacent slope before returning to the initial slope.
This procedure allowed more time for subsoil drainage between appli-
cations, hence, lateral surges of soil-water movement were reduced.
This simple management procedure can be adopted for manually
operated or automated systems even after the project has been
initiated.
Factors Commonly Ignored
Infiltration and drainage rates are influenced by water temper-
ature and water quality among many other important factors.
Infiltration rates determined in advance of irrigation may bear little
resemblance to those encountered when effluent is applied. The
hydraulic conductivity, K, of a soil varies with the physical proper-
ties of the soil together with the density and viscosity of water
applied. This is expressed by the equation
K - kpg/n (1)
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where p = density of water in gm/cm3
n = viscosity of water in dyne-sec/air
k = intrinsic permeability of soil or rock in cnr
g = acceleration due to gravity in on/sec2
K = hydraulic conductivity of soil or rock in cm/sec.
This equation has been applied to soil water flow in
unsaturated and saturated conditions.
The rate of flow is determined by Darcy's law
V = -Ki ' (2)
where V = volume of flux of water per unit cross-sectional area
K = hydraulic conductivity in on/sec
i = hydraulic gradient.
Frequently K is treated as a constant in field studies despite
the fact that it varies with the properties of the soil as well as
of the intrained water as noted above. Also intrinsic permeability
of soil or rock commonly is assumed to be constant unless there is
a change in soil characteristics. The fact that significant changes
in trinsic permeability can occur is frequently ignored when evalu-
ating infiltration and drainage characteristics of soils at proposed
irrigation sites. The mineralogy of soils together with quality of
effluent to be disposed of must be considered because clay soils can
expand in the presence of increased volumes of water or with changes
in water quality. Also changes in cations and anions in soils
resulting from exchange reactions can bring about dispersion reac-
tions that break up soil aggregates and plug soil pores. Swelling
and dispersion phenomenon both can drastically influence intrinsic
permeability, hence the infiltration capacity of a soil and its
drainage characteristics. Irrigation sites that initially had
favorable drainage characteristics experienced serious runoff prob-
lems with use for these and other reasons.
Temperature has a drastic effect on infiltration and drainage.
It influences the viscosity of water as well as its surface tension.
Eisenberg and Kauzmann, (1969) have shown that the viscosity of
water changes from 1.798 centipoises at 0°C to 0.8904 at 25°C.
Equation 1 instructs us that the hydraulic conductivity responds to
changes in temperature. Lowering the water temperature from 25°C to
0°C can decrease the hydraulic conductivity by one-half (Klock, 1972),
The effect of changes in density accompanying water temperature
changes is insignificant by comparison (equation 1). Weast (1968)
has shown how surface tension is effected by temperature which in-
fluences both infiltration and drainage. Surface tension is 75.60
dynes per cm at 0°C and 71.97 dynes per cm at 25°C.
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In his experiments, for example, he calculated from the capil-
lary rise equation that 19 percent of the water in a soil column
would remain after drainage at 0.3°C and observed 15.5 percent to
remain in experiments. An additional 1.7 percent of total available
water would be lost if the temperature increased from 0.3°C to 25°C.
The water content of a soil greatly influences its water trans-
mission properties which Bruce and Klute (1956) show to be a
maximum when the moisture content approaches 75-80 percent of pore
saturation.
The range in water temperatures likely to be encountered at
irrigation sites must also be considered when evaluating proposed or
potential irrigation sites and application rates.
Less well known are the infiltration characteristics of frozen
soils which are important in year around irrigation projects in
northern latitudes. At our winter irrigation site, 6 inches and 4
inches per week were applied the first winter partly in the belief
that more water may be required to keep the ground from freezing.
Also less land area and pipes were required to keep the system in
continuous operation to prevent ice damage to the trunk and distribu-
tion lines. We observed that whenever effluent was applied at
freezing to below freezing conditions (wet bulb temperatures near
32°F) ice began to develop first on twigs, tree trunks, needles,
grass, etc., until more massive ice packs developed. As long as
water was applied at below freezing temperatures, ice continued to
build to the point that it encrusted tree trunks and branches and
even began to encroach on spray heads. Where spray heads were close
to trees, ice grew around and over an occassional head which con-
tinued to supply water. Snow trapped in ice packs added to the
total amount of water in storage. Any day that effluent was applied
at above 32°F, the ice pack began to melt and water was available
for infiltration or runoff. Surprisingly, much of this melt water
stayed in close proximity to the ice packs indicating that some of
the water was stored in adjacent snow packs when snow was available
and some infiltrated into the soil beneath and adjacent to the ice
packs. Two points are clear. Ground frost development must be
limited or poorly developed below ice packs near spray heads.
Adjacent soils, although exposed and frozen, must retain some of
their infiltration and permeability characteristics. The water
content of soil near spray heads increases following the growing
season and should be sufficient to produce a rather tight ground
frost. However, the moment that an ice pack begins to accumulate
an insulation layer is formed which helps to prevent the further
development of frost. As the pack thickens and migrates laterally
around the spray head, it serves as a more effective insulator.
Water applied during thaws is available to permeate the ice pack
and help break up what ground frost may be present.
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Significant runoff may be observed particularly in the spring
when effluent is being applied, during warm rainy periods when ice
packs are still present. Adjacent soils, although frozen, cannot
be impermeable during these periods. Runoff has been observed to
enter forested border areas not receiving effluent and pond in
shallow depressions where it later infiltrates the soil or it in-
filtrates during overland flow.
Most investigators interested in the infiltration phenomenon
in frozen soils agree that the quantity and size of ice-free pores
is important. Work by Larkin (1962), Kuznik and Bezmenov (1963),
Post and Dreibelbis (1942) and others show that if a soil is
frozen when its moisture content is greater than field capacity,
its infiltration rate will be very low and if saturated, the intake
rate may be virtually zero. Gray et al. (1970) reports that other
experiments have shown that whenever an extremely wet layer within
the soil profile is frozen, downward movement of water through the
layer is impeded until the zone is thawed. Zavodchikov (1962)
showed that the infiltration rate of frozen soil may be increased
6-8 times its initial rate during the melting period which implies
that heat is added to the deeper frozen layers and helps to thaw
this ice. At our own site, heat contained in the effluent may be
sufficient to cause the repeated and early break-up of ground frost.
Even in areas that are flooded from time to time, free from snow and
later are exposed to below freezing temperatures, infiltration
continues during the next period of runoff. Ground frost may be
nearly impermeable at first in these areas, but it must thaw quickly
during the next runoff-ponding cycle.
It is also possible that not all voids are occupied by ice but
rather as the freezing process continues, the total dissolved solids
content increases to the point that the final "brine" produced does
not freeze. Small conductive channels may remain for this reason.
Recent studies by Jame and Norum (1972) support the conclusion
that in a frozen soil, unfrozen liquid water can exist in equilib-
rium with ice over a large temperature range below 0°C. Equations
developed by them using a concept of soil water potential helps to
explain the freezing-point depression of pore water that is brought
about in frozen soil. At a fixed value of soil water suction, or
soil water potential, there is a corresponding freezing point
depression which implies that for each moisture content there is a
corresponding freezing point depression. They explain that as
freezing occurs in the soil water system, water is transformed into
ice lenses, the amount of water remaining in the pores thus comes
under increasing suction or potential. This suction or potential
is believed responsible for the reduction of the freezing-point of
the remaining pore water. Presumably the remaining water is free
liquid water which can account for soil conductivities observed
below freezing temperatures.
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Whatever the mechanisms are that help to maintain infiltration,
excessive runoff should be anticipated at most project sites when-
ever irrigating in winter. Leeves or small dams will have to be
provided to prevent the trespass of these waters. Forest border
lands, natural depressions, or engineered interception structures
all can help infiltration and control runoff.
Ion Exchange Capacity
Physical-chemical processes operating in the soil that can add
to the renovation process are discussed by others in this proceedings.
It is sufficient to state that a high cation-anion exchange capacity
is desirable. Clay minerals, sesquioxides, abundant organic matter,
and other fine-grained mineral matter contribute to the exchange
capacity. The exchange capacity is relied upon to retain and store
exchangeable waste constituents within the shallow soil until they
can be assimilated by the biologic system at a later date. Exchange
and other physical-chemical reactions may also be relied upon to
store nutrients within the soil indefinitely. Phosphorus removal by
soil is a case in point. Even at the winter irrigation site where
6 inches per week of effluent were applied November through April,
the first year on sandy soils, phosphorus was not detected above
background concentrations even at shallow depths (3 to 17 feet).
Kardos has indicated that given our phosphorus concentrations and
2-inch per week year around application rate, 100 years would be
required to saturate even a 5-foot thick column of our soil with
phosphorus. If phosphorus were our only concern, higher application
rates could be used year around (>2 inches per week) successfully
for a prolonged period.
A soil's ability to physically retain effluent within the
biologically active zone is largely dependent upon its drainage
characteristics and its water content. Once the water content is in
excess of field capacity, water is free to move through the soil
after each new increment of water is applied. This moisture condi-
tion is prevalent during the late fall, winter and early spring when
the biologic system is less active and evaporation rates are low.
During this time, the adsorption capacity of the soil must be relied
upon to retain nutrients within the shallow soil. This is one of the
principle roles of the soil system during winter irrigation and when
applying effluent during periods of heavy rainfall. Swelling and
dispersion characteristics of soils are related to the mineralogy and
exchange capacity of soils and quality of water applied as has been
pointed out.
Soil Thickness
Evidence provided by Sopper and Kardos in this proceedings
support the conclusion that most renovation is achieved within the
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upper 3 to 4 feet of land surface where biological activity is at a
maximum. Some would debate, therefore, that a 3- to 4-foot thick
soil column should be adequate to provide the degree of treatment
required.
In carbonate terranes where bedrock is covered by thin residual
or transported soils, shallow voids and cavities are common near the
bedrock surface. Thin soils are especially prone to being washed
or piped into these voids under natural conditions. The process is
speeded up when additional water is added to the soil. Soil may be
eroded away and the soil and renovation media eliminated. Sinkholes
and piping voids become avenues for quick recharge that short circuit
unrenovated water to the water table. Two large piping holes devel-
oped at our reed canarygrass plot where a 2-inch per week application
rate has been maintained since 1965. Both occurred where soil was
40 to 60 feet thick. Similar but more numerous sink holes developed
at the Morgan Paper Company spray field near Lititz, Pennsylvania
where residual soils derived from carbonate bedrock average less than
10 feet in thickness. Sink holes can be backfilled as they develop
and covered with soil. This adds to the management responsibilities
where this problem applies. Subsurface erosion problems are not
normally experienced in most other geologic settings.
More than 3 to 4 feet of soil is desirable at irrigation sites
in humid regions located on other soil and rock types for other
reasons as well. Any site found to contain only 3 to 4 feet of soil
cover on the average is bound to contain a significant land area
where soils are likely to be even thinner than 3 feet. Most design-
ers of wastewater irrigation projects are likely to irrigate the
entire site rather than try to isolate numerous thin soil areas
unless required to do so. A detailed soil exploration program is
required at any site to be used for wastewater renovation but this
program can prove to be costly as test boring, test pits, seismic
shot lines, etc. have to be closely spaced. Even then, many thin
soil areas may be overlooked. I prefer to see 20 or more feet of
soil (unconsolidated deposits) above bedrock or a thick cover of
fine-grained soil above coarse-gravel or boulder gravel because
animal burrows often extend to bedrock and provide open channels for
surface runoff, application rates are always uneven in actual
practice and surface ponding, runoff, and subsurface lateral flow,
stem and trunk flow, and pipeline leaks all help to redistribute
effluent in an uneven manner at irrigation sites. Some parts of
the soil system, therefore are called upon to handle application
rates measured in feet of water per week rather than inches per
week as intended. Operational problems also arise from time to
time requiring that more water be applied than the designed amount.
All of these conditions increase the likelihood of breakthroughs of
incompletely treated effluent, hence, degradation of groundwater
and ultimately surface water quality in the vicinity of irrigation
projects.
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At winter irrigation sites 3 to 4 feet of soil is totally
inadequate in northern latitudes because the nutrient storage
potential of thin soils is apt to be inadequate and nutrients
(pollutants) will be flushed to the water table.
The thickness of the soil cover can be artifically increased
using top soil or suitable subsoil materials. Some would argue
that soil structure is important to the infiltration process, hence,
artificial fills should not be considered for irrigation. However,
even artificial fills can be designed to insure suitable infiltra-
tion and optimum drainage through careful selection and placement of
cover materials. Research work with coal mine spoil restoration
using sewage effluent and sludge show that it will not take long to
develop a lush cover of trees or grass even when comparatively poor
material (rock fragments) is being irrigated (Sopper and Kardos,
1972). A higher degree of renovation would be achieved the first
year if fine-grained material were used as cover material.
Topographic Setting
Slope is related to soil characteristics and runoff. Steeper
slopes will promote overland flow and subsurface lateral flow more
so than gentle slopes all other factors being equal. However, so
long as overland flow can be avoided, it should be possible to
irrigate rather steep slopes successfully under some field circum-
stances. It depends upon the amount of slope to be irrigated,
subsoil and water table conditions, design of laterals, application
rates, land use, and other factors. Also some projects will provide
for lagoon storage during winter and wet periods when slope begins
to exert a dominant influence on runoff.
Slopes can be engineered to some extent to provide contour
ditches, terraces, etc., to increase detention storage and infiltra-
tion. In addition to overland flow, subsurface seepage problems
are more likely to develop on steep slopes where groundwater dis-
charge areas begin to develop.
In more humid regions groundwater mounds tend to develop
beneath topographic highs in response to groundwater recharge.
Groundwater gradients are thereby increased during recharge periods
with the result that a greater amount of water is induced to flow
through an increased saturated thickness of soil or rock to regions
of discharge. Irrigation projects located where there is some local
relief and favorable permeability in the substrate can take advant-
age of the fact that there is space available for a water table
build-up beneath topographic highs. Also as gradients increase,
flow rates may be sufficient to transport recharge waters naturally
to points of discharge.
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In low relief to nearly flat areas water tables are commonly
at or very near land surface and there is little if any space for
additional recharge. Subsoil drainage must be provided artificially
to insure adequate drainage and aerobic conditions in the biologic-
ally active zone.
Drainage ditches, tile fields, drainage wells or water supply
wells may be used for this purpose but often at a considerable
additional expense to the project. File fields and drainage ditches
are preferable where they can be used because once they have been
installed they operate by gravity. Drainage wells and water supply
wells have pumping lift costs to contend with in addition to con-
struction, operation, and maintenance costs, which can add signifi-
cantly to total project costs. These factors should be considered
when selecting irrigation sites in low relief and poorly drained
areas.
Characteristics of the Groundwater Reservoir
Parizek and Myer (1968) stressed the importance of knowing the
location of groundwater recharge and discharge areas when selecting
wastewater renovation sites using land disposal methods. Irrigating
natural groundwater discharge areas with tie intent of achieving
recharge should produce a negative result. Renovated water is soon
rejected by the groundwater reservoir and lost by runoff and evapo-
transpiration. Still worse* poor drainage conditions and runoff
result, and soils may become waterlogged. This could cause the bio-
logically active zone to shift from an aerobic to anerobic state,
cause a destruction or alteration of the physical-chemical-biological
treatment processes, and ultimately a degradation of soil-, ground-,
and surface-water quality (Parizek and Myers, 1968). This basic
concern is complicated by the fact that recharge-discharge relation-
ships are not fixed. Rather, the boundary separating the two is
transient. Significant increases in the rates of recharge accompany-
ing irrigation can greatly expand discharge areas, particularly for
large projects. Areas that were formerly well drained recharge
areas may become poorly drained discharge areas. These areas can
occur several hundred to thousands of feet beyond stream channels
or appear as discontinuous upland patches remote from nearby streams.
k
Advantages of having relief on the water table have been dis-
cussed. In addition, there should be space available for a seasonal
build-up of the water table beyond natural conditions. Permeability
characteristics of saturated soil and rock should be sufficient to
convey reclaimed effluent to groundwater discharge areas. Where
both gradients and permeability are sufficient to facilitate lateral
'movement of reclaimed effluent and natural recharge, a considerable
savings can be achieved when compared to sites where this must be
done artificially.
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The question frequently arises, how deep should the water table
be at an irrigation site used for wastewater renovation? More
importantly, what is the seasonal range in water table position and
how will this be modified by additional recharge accompanying irri-
gation? The latter questions can be answered only by examining
soils at the site to see if they formed under conditions of a
seasonally high water table, by observing water table fluctuations
on site or similar adjacent sites at least a year in advance of
irrigation and by computing water table changes likely to be brought
about by irrigation. Soils are one of the most important and
reliable indices to the natural drainage (Table 3). As they formed
they integrated and thus reflect the results of years of favorable
or unfavorable drainage conditions. Soil properties are related to
both the depth of the water table and number of months during the
year that water is in contact with the soil profile, Schneider and
Erickson (1972) stress that even in dry months of the year the
natural soil drainage can be predicted by observing the color and
color pattern of each soil horizon, natural vegetation - whether it
is water-tolerant or water-loving, and position on the landscape.
This is important because water tables may fail to rise to their
maximum level during a particular series of dry years or during the
brief period of field study when irrigation sites are being selected.
The decision to artificially drain a site using wells, tile
fields, or ditches immediately limits the concern for the position
of water table because its position will be controlled or engineered
as required. Even when one is willing to do so, this does not mean
that artificial drainage can always be achieved at a reasonable
expense. Soils, for example, that are in the "extremely slow" to
"very slow" permeability class (Table 2) may be so nearly impervious
that leaching and artificial drainage are impossible using conven-
tional artificial means. Sites must be examined carefully with this
point in mind.
It would not be rational for regulatory agencies to arbitrarily
set a depth of water table position for example, at 6 or 10 feet, as
a requisite condition of irrigation sites. If this were done vast
areas in the United States with water tables less than this would be
eliminated from consideration. This would involve great expanses
of the mid west with little or no relief that had to be drained to
be farmed, and a significant percentage of areas covered by glacial
till. Farm land now being drained by tiles need not be suitable in
their present form, however, because a closer spacing and even a
deeper tile setting may be required to control both rainfall and
reclaimed effluent. On the other hand, where enforcement personnel
responsible for environmental protection are few in number and over-
taxed with work, more stringent site requirements are justified.
Sites can be selected with wastewater renovation as the sole
purpose. Under these circumstances renovation is to be achieved in
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TABLE 3. Soil' Class by Drainage, Color Appearance, and Water Table
Position (From Schenider and Erickson, 1972)
Soil class
Color
Water table conditions
Well-drained
Bright red, yellow, and
brown. Free of mottles
to a depth of 36 to 42
inches or more.
Water table commonly
greater than 60 inches
during most months.
Moderately well-
drained
Uniform red, yellow or
brown colors in the sur-
face and upper subsoil
horizons. Mottles
present in the lower
subsoil and parent or
underlying materials.
Somewhat poorly
drained (imper-
fectly drained)
Generally mottled direct-
ly below surface horizon.
Color matrix below sur-
face layer is dominantly
yellow and brown with
gray, rust brown, and
orange mottles.
Mottled conditions in-
dicate the presence of
a high water table dur-
ing some parts of the
year, usually spring,
late fall and winter
months. Seasonally,
water table ranges from
24 to 120 inches in
depth.
Poorly drained
Dark-colored surface
layer high in organic
matter. Horizon below
the surface layer pre-
dominantly gray with
orange, brown, rust
brown or yellow mottles.
High water table at or
within 30 inches of
surface most of the year
unless artificially
drained.
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advance of a more distant present or possible future water use.
Parizek and Myers (1968) indicated that site selection criteria for
a renovation system favoring distant reuse will depart from those
favoring local reuse as groundwater. Shallow penetration of reno-
vated effluent and rapid return to the surface may be acceptable.
This can be achieved by irrigating side hill slopes and local up-
lands that favor the surface return of waters after a sufficient
degree of treatment has been achieved. Irrigation on local uplands
surrounded by nearby valleys and on stratified deposits favoring
the development and lateral movement of perched groundwater are
common settings where this can be achieved. Loess overlying
glacial till, shale or siltstone bedrock, lake clay, lake silts and
sands, fluvitile silts and sands, dune sand, residual and other
transported soils that overlie deposits with low permeability char-
acteristics are cases in point. The percentage of land area that
would favor renovation but unimportant groundwater recharge is
greater for many states than is land that would favor significant
increases in groundwater recharge for local reuse.
Groundwater recharge for local reuse may be an important
objective at some project sites. Examples have been cited above
where infiltration, renovation, and quick return to land surface
can be achieved. In these cases, reclaimed effluent may be avail-
able for reuse off-site as surface water, it may be recaptured by
wells located downstream by induced streambed infiltration, or used
for recreational purposes or wildlife propagation (Parizek and Myers,
1968).
Water supply wells may be located beneath or adjacent to irri-
gation sites to derive benefits of reclaimed water. Wells may be
planned to improve drainage as well as to supply water. In both
instances, the number and spacing of wells required to provide the
necessary amount of water will depend upon aquifer characteristics--
storage, transmission properties, boundry conditions, recharge
rates--and degree of treatment anticipated, amount of land to be
irrigated, application rates and evapotranspiration requirements.
The number and spacing of onsite wells necessary to insure
drainage may depend upon the volume of water required from the
well field, depth and extent of pumping cones of depression developed
for each well, economic considerations, and aquifer hydrologic char-
acteristics.
Parizek and Myers (1968) point out that pumping cones of
depression within the free-water surface or water table are ideal
for dewatering some unconfined soil and rock aquifers and for de-
riving direct benefit from artificial recharge. Five plans of action
are possible: (1) a wastewater renovation facility can be located
adjacent to an existing well field where site conditions are suitable
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for irrigation, and effluent used is free of toxic or harmful non-
degradable substances that otherwise are not likely to be removed
in the renovation media, (2) a well field can be placed in close
proximity of the site after it has been established that adequate
renovation is being achieved, (3) reclaimed water discharged to
surface can be re-collected in wells relying upon induced stream-
bed infiltration, or (4) drainage wells can be placed within the
irrigation area with no beneficial use planned for the water except
to insure adequate drainage. Where there is doubt that adequate
renovation can be achieved without relying upon dilution as well,
the irrigation site should be located remote from areas of existing
or potential groundwater development.
For cases 1 through 4, to be effective, unconfined aquifers, or
at least, semi-unconfined aquifers should underlie the irrigation
site (Parizek and Myers, 1968). These may be of diverse origin and
be composed of fractured bedrock--sandstones, siltstones, carbonate
rocks, gneisses and schists--sedimentary rocks containing favorable
intergranular or primary permeability--sands tone, silts tone,
carbonate rocks--or of permeable unconsolidated sediments such as
sand and gravel.
Where confining beds are thick or relatively low in permeabil-
ity, confined aquifers may derive little additional recharge than
was being achieved under natural conditions. Once the maximum
hydraulic gradient has been developed between the source bed and
confined aquifer in response to recharge and pumpage, vertical leak-
age rates are fixed. Where recharge rates to source beds are in
excess of the vertical leakage rate to the confined aquifer, water
is rejected from the shallow system and no additional recharge
benefits are achieved.
Selected vertical hydraulic conductivities for soil and rock
units are presented in Table 4 as a guide.
One point cannot be overstressed. A large volume of recharge
should be expected when irrigating in humid regions even when only
a 2-inch per week rate is used during the growing season. Even
more recharge is achieved with year around irrigation.
Over 78 feet of effluent has been applied at the Perm State
facility to plots irrigated at a rate of 2 inches per week, 12
months a year starting in 1964. Based on calculated evapotranspir-
ation losses, between 59 to 100 percent of the applied water was
potentially available for recharge depending upon the rate of
application used, length of irrigation period and weather conditions
experienced that year. The lesser amount occurred when effluent was
applied April through November during a drought year, whereas, the
100 percent value was for a year when rainfall exceeded evapotrans-
piration by 6.01 inches (Table 5).
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TABLE 4. Vertical Hydraulic Conductivities for Soil and Rock Units
Determined from Field Testing Procedures
Vertical
Hydraulic
Conductivity
in gpd/ft2
Range
1.02 -1.60
0.10 -0.63
0.01 -0.08
0.005 -0.011
0.005 -
Average
1.31
0.25
0.03
0.008
0.005
Material Examined Source
Glacial drift in Illinois; Walton
sand and gravel, some clay
and silt
Glacial drift in Illinois; "
clay and silt with consider-
able sand and gravel
Glacial drift in Illinois; "
clay and silt with some sand
and gravel
Glacial drift in Illinois; "
clay and silt with some sand
and gravel and dolomite
Glacial drift in Illinois;
clay and silt with some sand
and gravel and shaley dolomite
(1965)
0.00005-.00007
0.00005-.0007
0.0008 -0.9
0.01 -0.5
0.03 -0.16
0.08 -0.02
0.0003 -0.5
Dolomite, with shale
Maquoketa shale, northern
Illinois
Glacial till in northeastern
Ohio
Surficial till, Montgomery
Co. Ohio
Buried till, Montgomery Co.
Ohio
Glacial till, southern Illinois
Glacial till, South Dakota
Morris (1962)
Hydraulic Conductivity
in gpd/ft2
0.001 -2.0
100 -3,000
1,000 -15,000
200 -5,000
0.1 -50
0.00001 -0.1
Clay, silt
Sand
Gravel
Sand and gravel
Sandstone
Shale
Walton (1970)
tt
it
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TABLE 5. Recharge by Sewage Effluent for 1-Inch and 2-Inch
Application Rates by Year at the Pennsylvania State
University Project Site
Year
1963
1963
1964
1964
1965
Application Rate
Inches per Week
(April through
November)
1
2
1
2
2
Percent
Potential
Recovery
65.5
82.7
59.8
79.9
Remarks
Agronomic crops:
Glaney- Griddle
method.
Recharge
(g/acre/yr)
427,000
1,078,000
1,493,000
Inches of Recharge
1963
1963
1964
1964
1965
1967
1
2
1
2
2
2
18
41
26
59
--
--
Forestry plots:
Thornthwaite
method
488,700
1,113,000
706,000
1,602,000
1,493,000
1,859,000
(After Parizek et al., 1967, and Kardos, 1970; and Sopper, 1971)
Recharge rates were higher at all plots irrigated on a 12 month
per year basis and during years of normal to above normal precipita-
tion. As evapotranspiration rates diminish during the late fall,
winter and spring, nearly all applied effluent and precipitation are
available for recharge at our site. Losses by runoff are negligible.
Annual recharge rates might approximate 2.9 million gallons per
year where 2 inches per .week are applied on a year around basis to
135 acres, 1.5 billion gallons for a 600-acre project, etc. For
projects involving thousands of acres (Muskegon County, Michigan,
various projects proposed by the U.S. Army Corps of Engineers) vast
amounts of recharge would be involved. These projects will and have
required detailed hydrogeologic investigations of proposed irriga-
tion sites and a hydrogeologic systems analysis to determine what
effect irrigation waters are likely to have on recharge and regional
water table configurations. Such analyses will help to delineate
areas likely to be flooded both on and adjacent to irrigation plots,
the need for and density and distribution of drainage facilities,
and their effect on water tables during irrigation. For some pro-
jects, potential problem areas will be delineated that may or may
not cause problems once the project has been placed into operation.
Contingency plans to eliminate potential drainage problems can be
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included at the time irrigation projects are designed and submitted
for approval to regulatory agencies. Control measures, in turn,
would be added to the system only after it has been shown that they
are required through actual experience.
Large irrigation projects involving hundreds or thousands of
acres of land are more difficult to analyze because as the land
requirement increases the soils, geologic and hydrologic diversity
and complexity are more likely to increase. Water table level
responses at these sites will require analyses using electrical
analog or digital modeling techniques rather than conventional
analytical methods which assumes more nearly ideal conditions. Data
requirements for modeling soil-water and groundwater flow under
complex field conditions also become more demanding because all
elements required in the models must be accounted for during field
studies either through actual measurement or "educated" guesswork.
Fortunately, computers are now available that allow solution of
large sets of simultaneous equations that can predict cause and
effect phenomenon in heterogeneous aquifer and confining bed systems
under a wide variety of recharge and no flow boundary conditions.
Generalized digital computer programs have been written to simulate
one-, two- and three-dimensional steady and nonsteady flow of ground-
water in heterogeneous deposits under water table, nonleaky and
leaky artesian conditions. Programming techniques allow for varying
pumpage from wells, varying natural or artificial recharge rates,
relationship between exchange between surface waters and the ground-
water reservoir, influence of drainage facilities on water table
level, groundwater evapotranspiration and similar other complexities
frequently encountered in the field (Douglas and Rachford, 1956;
Zienkiewicz and Cheung, 1965; Zienkiewicz, Mayer and Cheung, 1966;
Finder and Bredehoeft, 1968; Bittinger, Duke and Longenbaugh, 1967;
Bredehoeft, 1970; Cooley and Peters, 1970; Cooley, 1970; Prickett
and Lonnquist, 1971; and Finder, 1971).
These analytical procedures make it possible to deteimine the
water table configuration that will develop in response to natural
recharge and various schemes of groundwater development. The problem
is identical for sewage effluent irrigation projects with the excep-
tion that recharge rates are greatly increased. However, basic data
requirements must be met through detailed hydrogeologic investigations
frequently involving geologic mapping, test drilling programs, control
pumping tests, etc. Most project areas will require definition of
the following variables:
1. Coefficient of vertical and horizontal permeability distri-
butions for aquifers and confining beds.
2. Specific yield of deposits saturated or dewatered by water
table fluctuations, and coefficients of storage for confined
aquifers.
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3. Thickness and distribution of aquifer and confining units.
4. Location and character of hydraulic boundary conditions,
including recharge and nonflow boundaries.
5. Water table and potentiometric surface configurations for
unconfined and confined aquifers with seasonal changes.
6. Location and amount of natural recharge and artificial
recharge expected from the applied effluent.
7. Location of groundwater withdrawal points and annual
pumping schedule.
8. Estimated groundwater evapotranspiration losses for the
area where water tables are within 10 or less feet of land
surface.
Analyses of groundwater systems can now be made for rather
complex field situations. These analyses should be demanded by
regulatory agencies responsible for evaluating proposals for large
scale irrigation projects. These same analysis procedures may be
used to determine drawdowns likely to be brought about by drainage
ditches, tile fields, water supply and relief wells proposed to
control water levels.
Hydrologic Isolation, Dilution and Dispersion
The groundwater reservoir can serve other roles as well. Some
waste constituents are likely to be contained in sewage effluent
that cannot be renovated by biological or biochemical processes or
physical chemical processes operating within the soil. Ultimately
these will find their way to the groundwater reservoir. Difficult
or impossible to renovate trace elements and other substances that
are likely to pass through the renovation system unaltered or little
altered can be isolated within groundwater flow systems. These
remaining substances, in turn, can be diluted to acceptable concen-
trations within nearby streams and lakes. A groundwater hydrologic
isolation system will work only as long as groundwater flow systems
are more or less in a steady state condition. Any change in the
nearby groundwater recharge-discharge regimen, change in hydrologic
boundary conditions brought about by new groundwater development,
excavations, or mining can cause a shift in the flow regimen, there-
fore a change in the system being relied upon to achieve isolation.
It should be remembered that these waste constituents may survive
for years to tens of years within the groundwater reservoir once
they have been introduced and a procedure of "controlled contamin-
ation" or controlled pollution is being adopted.
118
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A more detailed hydrologic analysis is justified where such a
system is to be used compared to a system where renovation is likely
to be more complete.
Aside from a hydrological isolation role, the soil-water and
groundwater reservoirs may be relied upon to provide dilution and
dispersion of waste materials.
All nonbiodegradable substances and wastes not involved in
physical-chemical reactions within the soil-water and groundwater
reservoirs must be accounted for in this manner whether intended or
not. A basic question arises. If waste substances cannot be
removed within the renovation media by any of a combination of
processes involved, should they be allowed in sewage or other efflu-
ents applied to the land and if so in what concentrations? Trace
elements, heavy metals, and other more difficult to handle wastes
derived from industrial processes may have to be excluded from
, irrigation systems or at least strictly controlled and monitored.
Many of these same wastes do not belong in our rivers or lakes
either.
Toxic wastes pose a problem. They may poison biological systems
responsible for key renovation processes. They may cause slow, but
long term and difficult to correct damage to groundwater quality.
They may be concentrated within plants used for agricultural produc-
tion and cause related difficulties when used as food or feed.
Spectacular irrigation project failures may be cited where oil field
brine or chemical wastes have been applied to the land.
Where potentially harmful substances are included in sewage
effluent, that will be applied to the land, an analysis should be
made to determine the concentration that may result as a function of
volume and quality of water applied, time since application and
distance of travel within the soil-water and groundwater reservoirs
beneath and adjacent to the irrigation site. Conservative estimates
can be made for design purposes by assuming that only dilution and
dispersion is being relied upon to reduce the concentration of a
particular substance. A more complete and representative analysis
of the real complexities involved is the subject of ongoing study by
various people. Ultimately it will be possible to include biochemi-
cal and geochemical reactions in addition to physical processes now
being used in these analyses to study flow in saturated and un-
saturated systems.
It is first necessary to determine the seepage velocity within
all reference elements of the groundwater reservoir that influence
groundwater flow in the vicinity of an irrigation site. All of the
basic data requirements specified earlier that are required in
groundwater systems analyses must be met. In addition, the porosity
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of saturated soil and rock must be known to deteimine the average
seepage velocity for the deposits in question. Also the waste
concentration, total waste load applied with time and area of
application must be known. Horizontal and longitudinal dispersion
coefficients must be known for all saturated soil and rock en-
countered. These hydrologic parameters are essentially unknown
for most naturally occurring soil and rock which further complicate
these analyses.
The theoretical basis and derivations of dispersion equations
are presented by Bear, Zaslavsky and Irmay (1968), Reddell and
Sunada (1970), Ogata (1970) and Bredehoeft and Finder (1972).
If no chemical reactions occur between the water and the aquifer
or soil materials which affect the dissolved-solids concentration,
then equation 3 describes the mass transport and dispersion of dis-
solved chemical constituents in a saturated porous media.
3C 3 /TV . 3C \ 3(qiC) . ^ n
n — = i- I Dii . .. 1 - >^,. ' + Lp G ,-•*
3t 3X1 I J 3XJ ) 3 XI y x (3)
where C is the mass concentration of dissolved solids (m/Ir),
Dij is the coefficient of hydrodynamic dispersion (I//T)
Cp is the mass concentration of dissolved solids at a source or
sink (m/L^)
and Q is the rate of production of a source (L^/T).
The first term on the right hand represents movement of dis-
solved solids due to hydrodynamic dispersion, and is assumed to be
proportional to the concentration gradient. The second term repre-
sents convective transport, which is proportional to the seepage
velocity. The third term is a fluid source or sink.
Bear, Zaslavsky, and Irmay (1968) conclude that two processes
account for hydrodynamic dispersion. One is mechanical dispersion,
which depends upon both the flow of the fluid and the nature of the
pore system through which flow takes place. The second is molecular
diffusion which is time dependent and becomes significant at low
flow velocities. In two recent field studies, Bredehoeft and Finder
(1972) and Konikow (1973) showed diffusion to be of little consequence,
Scheidegger (1961) expressed the relationship between the dis-
persion coefficient, fluid flow, and the pore system as
Dij = «ijmn
where «ijmn is the dispersivity of the porous medium (L),
Vm Vh are the components of velocity in the m and n directions
(L/T), and
V is the magnitude of velocity (L/T).
120
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Further, for isotrqpic porous medium the dispersivity tensor is
defined by the constant *i, the longitudinal dispersivity of th
medium, and *jj, the transverse dispersivity. These are relate
the longitudinal and transverse dispersion coefficients by
DL = ttiv
DT • «nv C6)
The method of characteristics is used to solve equation (3) Finder
and Cooper (1970), Reddell and Sunada (1970), and Bredehoeft and
Finder (1972).
Konikow (1973) presented the most complete field study that
demonstrated the applicability of the theory in predicting shallow
groundwater quality changes resulting from irrigation practice in a
semi-arid region.
Digital solution of complex groundwater flow and chemical
transport equations involved will provide a conservative estimate
of the waste concentration that will result if no other renovation
processes are involved.
These analyses should be demanded of designers of wastewater
irrigation projects where there is doubt about the water quality
conditions that may result in response to prolonged irrigation.
These analyses will provide some estimate of how much of a buffer
zone should be allowed between spray fields and wells and springs
used as water supplies.
Design of Monitoring Facilities
All wastewater irrigation projects must contain appropriate
monitoring facilities so that the designers' claims and expectations
can be verified through actual experience. Wastewaters, soils,
geologic and hydrologic settings, operating and management procedures
are so varied that it is not safe to assume that if the irrigation
method worked in one area it will automatically work in an adjacent
area with a similar setting. Operator and management variations
alone can cause the demise of a particular project. Cases can be
cite'd where the recommended total annual application amount was
applied to a plot within a two- or three-week period rather than on
a weekly year around basis. Groundwater pollution, vegetation kills,
water logging of soils, surface runoff and soil erosion resulted at
these sites. The simple act of irrigating wastewaters is not suffi-
cient to insure renovation. A missapplication of the technique can
do a disservice to the living filter-irrigation concept.
Regulatory agencies should demand the installation of monitoring
facilities at all wastewater irrigation projects and require routine
performance reports of the operator. Some would argue that since
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only one sample point is required to evaluate the performance of
sewage treatment plants, the effluent outflow line, only one point
should be required at irrigation project sites. This is absurd in
view of the field complexities involved. A question arises. How
many monitoring points are necessary, how should they be constructed,
where should they be located, how frequently should samples be taken,
what waste constituents should be examined for, for how long should
sampling continue, what analyses techniques should be applied, etc.?
For example, soil water samples collected from 6 feet below an irri-
gation site will produce different results when compared to samples
taken from monitoring wells completed in the water table below
irrigation plots or when compared to samples collected from wells
located in the direction of groundwater flow but adjacent to irriga-
ted areas. It is also necessary to determine how representative a
sample station is when compared to the general conditions encountered
at the site. Regulatory agencies must determine what water quality
standards should be met for each of the sampling regimes—on site
soil-water and groundwater, and groundwater adjacent to the site.
Only several hydrogeologic factors are considered here to
illustrate the caution that must be exercised. A variety of monitor-
ing devices and sampling stations were designed and installed at the
Perm State Waste Water Renovation and Research Facility, (Parizek
elt al., 1967). These were intended for research purposes, hence the
numEer and diversity of stations and frequency of sampling was con-
siderably greater than would be required for routine projects.
Sampling water within the soil-moisture reservoir - above the
water table - poses special problems because water is normally under
tension and will not enter bore holes unless perched groundwater
lenses develop. Shallow and deep pan and pressure-vacuum lysimeters
were used to collect soil-water samples at the Penn State facility
.as well as sand-point wells, and soil samples. The advantages and
disadvantages of pan and pressure-vacuum lysimeters design and con-
struction procedures used are described by Parizek and Lane (1968).
Pressure-vacuum lysimeters represent the single best approach to
sampling soil water or water under tension. They are inexpensive,
easy to install, provide samples long after other sampling devices
fail as the moisture content is reduced and can be used at depths
of 6 inches to more than 60 feet. Commercial lysimeters are avail-
able and can be modified to provide water samples below 20 or more
feet (Parizek and Lane, 1968). These can be stacked within indivi-
dual bore holes and provide soil-water samples at any interval
within soil. It is possible, therefore, to determine the degree of
renovation being achieved with time and depth on a systematic basis
below irrigation plots.
Sampling water within unsaturated bedrock poses other problems
where deep water tables are encountered within bedrock. A variety
of well types and pumps can be used to obtain effluent samples from
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the groundwater reservoir. Ideally, monitoring wells should be
pumped long enough to induce flow from adjacent soil or rock
deposits, thereby increasing the chance of providing a more repre-
sentative sample of groundwater within the vicinity of the well.
Hand bailing a few gallons from a 6-inch diameter well, for
example, might represent only a 1/4,000,000 or less part or
sample of water recharged at a 100-acre irrigation site.
Groundwater flow systems must also be considered when design-
ing monitoring wells. Wells may be located above or below flow
channels containing effluent hence, fail to provide samples of
effluent recharged to the groundwater reservoir. Depending upon
the hydrogeologic setting involved, pumping may increase the chance
of obtaining representative samples or have little effect. Chances
of bypassing are greatly increased where monitoring wells are
completed in fractured rocks. Fractures greatly increase the
permeability of rock over that of the more massive blocks of rock
they enclose. The number, distribution, orientation and aperature
size of rock fractures or joints and bedding plane separations
rarely can be determined for irrigation sites because these sites
should contain a soil cover even to be considered for irrigation.
Hence, there is risk that unclaimed effluent may escape the site
undetected.
Zones of fracture concentration revealed by fracture traces,
on the other hand, can be routinely mapped on areal photographs.
These delineated zones of intensive jointing and physical and
chemical weathering hence increased permeability and porosity that
may be 10 to 1,000 times more permeable than adjacent rock. (Lattman
and Parizek, 1964; Parizek and Voight, 1970; Siddiqui and Parizek,
1971; Parizek, 1971 a, b).
Monitoring wells located on fracture traces can greatly increase
the chances of obtaining a representative sample of groundwater
beneath and adjacent to irrigation sites because they concentrate
flow and serve as conduit-like systems that are interconnected on a
regional basis. Monitoring wells located remote from these zones
may fail to reveal pollution problems developing on site, either
because they channel effluent away from irrigation sites or provide
dilution where adjacent groundwater enters the site.
Zones of fracture concentration can serve another important
function where well dewatering or groundwater reuse is planned in
areas underlain by fractured rocks. These zones serve as efficient
groundwater collector channels when tapped by wells. Fewer de-
watering wells would be required to control groundwater levels in
fractured rocks where wells are placed at fracture trace inter-
sections compared with cases where wells would be drilled without
knowledge of these zones. Zones of fracture concentration are
123
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narrow, hence are not often penetrated by chance. This would be
of vital importance in large projects where dozens of dewatering
wells might be involved. Dewatering using zones of fracture con-
centrations can be achieved with a fraction of the total number of
wells that otherwise might be required.
These same zones greatly increase the yield potential of water
supply wells. Siddiqui and Parizek (1971) showed the percent of _
fracture trace wells whose yield values equalled or exceeded specific
values when compared with wells located remote from fracture traces.
Data presented are for wells completed in shale, shaley limestone,
limestone, dolomites, with various textures and sandy dolomites
located in central Pennsylvania. Similar relationships are being
found for other rock types in Pennsylvania and elsewhere as well.
Fracture trace and fracture-trace intersection wells in all cases
are among the most productive wells being drilled within various
rock types when compared to wells drilled off these zones in the
same terrane.
Adminis trative Cons iderations
A wealth of experience is available on applying irrigation
water to crops. However, data are still scant on the use of sewage
effluent as irrigation water to determine the degree of renovation
that may be achieved under varied crop and climatic conditions.
Many have irrigated with sewage effluent but with little concern
of the pollution potential involved. A number of questions become
obvious when one considers land disposal and treatment of waste-
waters. Many of these were considered in the design of the Penn
State research project and must be considered by others who are
seeking alternative solutions to wastewater treatment and disposal
problems. Some of these have been listed and discussed by Parizek
et al (1967), Parizek and Myers, (1968), and Parizek (1971c).
Regulatory agencies charged with the responsibility of reviewing
waste treatment and disposal applications and with enforcement are
or will be forced to decide often with scanty data whether to grant
operating permits for wastewater irrigation systems. Some states
may grant one-year experimental or provisional permits until they
are assured projects are performing up to expectation.
Soil-water and groundwater flow rates frequently are so slow
that months or even years may be required before applied effluent
reaches a particular monitoring station. For instance, on the Penn
State Project soil water was being sampled from a perched groundwater
lens within a loamy soil. The monitoring point is located at a depth
of 33 feet below surface where effluent is applied April through
November. Chlorides, which serve as our best tracer, did not begin
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to increase above background concentrations until 13 months after
irrigation began.
Nearly two years were required before detectable changes in
chloride and nitrate were noted in groundwater monitoring wells
located 275 feet below irrigation sites containing nearly 60 to 100
feet of clay to sandy clay soil and 100 to 200 feet of unsaturated
cavernous dolomite bedrock. Monitoring wells in each case were
open to the top of the water table and equipped with pumps.
Monitoring installations must be planned to allow an early
evaluation of irrigation projects as well as the long term response
of these systems. Both were allowed for in the Perm State project
with the result that water quality changes within the deep ground-
water reservoir have been noted after nine years of irrigation but
the quality changes are entirely acceptable. In fact it is of
better quality than the average groundwater supply being used for
domestic and farm purposes within the adjacent valley area.
Other problems arise when attempting to evaluate monitoring
results. Seasonal changes in land use, weather, recharge, rates of
physical, chemical and biological processes produce erratic graph-
ical plots of water quality when a given constituent is considered.
It is difficult to establish meaningful trends in such data even
after two or more years of irrigation let alone account for the
possible sources and reasons for the variability observed. In
short, the success or ultimate failure of a particular project can-
not be judged in the short term. Monitoring must be continued for
the life of the project even if to a limited extent once initial
success has been established.
CONCLUSIONS
1. Knowledge of the soils, geology and hydrology can help
when selecting sites for wastewater renovation to insure that a
high degree of renovation is achieved for a prolonged period, to
insure that groundwater recharge and/or reuse can be achieved and
to minimize secondary environmental problems that can result from
wastewater irrigation projects.
2. This same knowledge must be applied to the design of
monitoring systems used to evaluate these projects.
3. Regulatory agencies responsible for the evaluation of
irrigation proposals and policing and enforcement work need divers-
ified personnel to deal with wastewater irrigation projects. Aside
from sanitarians, soil scientists, groundwater geologists and
related personnel are required. Regulation and enforcement are
mandatory to insure the success of irrigation projects.
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4. As the size of irrigation projects increase, the likelihood
for major failures will increase. Numerous small scale projects
have already failed due to poor design, improper site selection and
poor management. More attention will have to be given to details of
site selection, use of a conservative design, and continued project
management. Management is the key to achieving a high degree of
renovation over the long term at good sites and of making the best
of poor sites.
5. Wastewater irrigation projects are different from normal
fresh water irrigation projects. Many sites are entirely unsuited
for wastewater treatment using the irrigation method.
6. Many sites that may appear to be unsuited for wastewater
irrigation may in fact be made suitable through the use of imagin-
ative engineering practices.
7. The concentrations of harmful trace elements and toxic
substances not likely to be removed in the renovation media may well
have to be controlled in irrigation waters or reduced or eliminated
in advance of land disposal. Extensive soil-water and groundwater
pollution and pollutants can persist for generations within the
subsurface.
8. Recent theoretical developments and increased size of
computers make it possible to evaluate regional water level changes
likely to be brought about by large irrigation projects under complex
field sites as well as to estimate quality changes likely to result
from dilution, dispersion and other mechanisms operating within the
soil-water and groundwater reservoirs. This capability should be
exploited when designing large projects as our total documented
experience with wastewater irrigation projects is still limited
despite the number of irrigation projects in use.
9. Regulatory agencies, should not be shortsighted in the levels
of treatment they require of spray irrigation projects. If only
phosphorous is to be removed, high application volumes--2,6 or more
inches per week--might be used on a variety of soils with success.
However, pollution may result from other points of view, MBAS,
nitrates, etc. The physical-chemical-biological processes operating
in the soil can be relied upon to provide a high degree of renovation
of a number of constituents from the outset if allowed to do so.
10. Land ownership will greatly increase the cost of spray
irrigation projects when compared to other methods of treatment
particularly where real estate values are high. It would appear
reasonable that long term lease agreements would be a suitable basis
for state and federal funding of irrigation projects. Arrangements
might be possible where land owners are paid for the use of their
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land where water and nutrients are in excess of their needs but pay
for these when they need them.
11. Hopefully the idea that irrigation projects are only
suitable for small towns, trailer courts, and small industries is
dead. The concept is applicable to major metropolitan centers as
well. Public water supplies for these major centers are rarely de-
rived from within city limits. Rather, water may be imported from
sources 50 or more miles away. By contrast, wastewater treatment
facilities have traditionally been located in the topographically
low end of town for economic reasons. Large scale projects being
planned or dreamed about show that these waters can be returned to
their region of origin so that they might be renovated and made
available for reuse. The problems involved are more apt to be
political than technical or economical.
ACKNOWLEDGEMENT
Portions of this research were supported by funds from
Demonstration Project Grant WPD 95-01 received initially from the
Division of Water Supply and Pollution Control of the Department
of Health, Education, and Welfare and subsequently from the Federal
Water Pollution Control Administration, Department of the Interior.
Partial support was also provided by the Office of Water Resources
Research, USDI, as authorized under the Water Resources Research
Act of 1964, Public Law 88-379.
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128
-------
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130
-------
RENOVATION OF MUNICIPAL WASTEWATER THROUGH LAND
DISPOSAL BY SPRAY IRRIGATION
Louis T. Kardos and William E. Sopper
Department of Agronomy and School of Forest Resources
The Pennsylvania State University
Diversion of treated municipal wastewater from its usual
disposal medium, surface waters, to the land means that the diverted
wastewater with all its constituents must ultimately reside in the
soil or be removed from the soil in harvested vegetation, by vapor
loss to the atmosphere or by movement in the soil solution to the
groundwater. The latter in turn may cycle as base flow to the sur-
face waters or be re-used as a pumped water supply. It is impera-
tive therefore that the quality changes in the wastewater as it
passes through the living filter, the soil and its associated
biosysterns, be documented and evaluated.
In the Penn State project this was accomplished by extracting
soil solution samples with suction lysimeters installed at various
depths in the soil profile. Soil water samplers were obtained from
Soil Moisture Equipment Co., Santa Barbara, California. Details
concerning the method of installation and operation of these other
monitoring systems are given in Penn State Studies No. 23 (Parizek
et^ al., 1967). The chemical quality of the chlorinated secondary
treated wastewater was monitored by obtaining a composite of the
wastewater being applied through the sprinklers during each irriga-
tion sequence. Irrigation application rates were 0.25 inches per
hour and amounts applied were 0, 1, 2, or 4 inches at weekly
intervals. Various sites received irrigation ranging from 16 to 32
weeks (Apr.-Nov.) on the corn rotation area, 40 to 50 weeks (Jan.-
Dec.) on the reed canarygrass area and 23 to 52 weeks (either Apr. -
Nov. or Jan.-Dec.) on forested areas. The irrigation programs and
soil types for these areas are shown in Table 1. Detailed descrip-
tions of the soil types are given in Parizek et al. (1967). Average
annual concentration of various constituents In th~e applied waste-
water are shown for the corn rotation area for 1963-70 in Table 2
and' are representative of the concentrations in wastewater applied
to the other areas.
The extent of renovation of the applied wastewater may be
expressed as the change in mean annual concentration of a particular
constituent in the applied wastewater when compared with that found
in the soil solution in the suction lysimeters. However this compu-
tation is not applicable to the nitrogen components since they are
biologically changed from one form to another. Because nitrate-N is
a widely used limiting parameter for drinking water, the overall
131
-------
Table 1. Irrigation Programs for Agronomy and Forestry Areas
Vegetative Soili'
Cover
Rotation-Corn
Rotation- Corn
Hardwoods
Red Pine
Red Pine
Old Field
Reed canarygrass
Hardwoods
H
H
H
H
H
H
H
M
Weekly
Application
in
Inches 1963
June-
1
2
1
1
2
2
2
2
Dec.
24
48
23
23
46
46
—
--
1964
March-
Nov.
33
66
33
33
66
66
July-
Nov.
36
--
Seasonal Irrigation Amounts in Inches
1965 1966 1967 1968 1969 1970
April- April- April- April- April- April-
Nov.
29
58
30
30
60
60
Apr.-
Dec.
80
Nov. 23-
Dec.
12
Nov.
32
64
32
32
64
64
Jan.-
Dec.
78
Jan.-
Dec.
104
Nov.
26
52
28
28
56
56
Jan.-
Dec.
94
Jan.-
Dec.
104
Oct.
20
40
31
31
62
62
Jan.-
Dec.
98
Jan.-
Dec.
102
Oct.
16
32
28
28
56
56
Jan. -
Dec.
100
Jan.-
Dec.
104
Oct.
16
32
25
25
50
50
Jan.-
Dec.
86
Jan.-
Dec.
90
Total
196
392
230
230
460
460
572
516
—' H = Hublersburg silt loam or clay loam
M = Morrison sandy loam
-------
Table 2. Average Concentration of Various Constituents in Wastewater Applied to the Corn Rotation
Area at Rates of One and Two Inches Per Week During 1963 to 1970.
1963
1964
1965
1966
1967
Constituent
1
2
1
2
1
2
1
2
1
2
Concentration (mg/1)
Phosphorus
MBAS
Nitrate-N
Organic -Ni/
Potassium
Calcium
Magnesium
Sodium
Manganese
Chloride
Boron
pH
9.680
3.17
5.7
7.3
17.1
32.4
18.5
46.0
t
43.4
t
7.3
9.720
3.20
5.8
7.3
16.8
32.3
19.0
46.9
t
43.9
t
7.3
8.620
1.47
14.9
3.7
16.4
35.6
19.2
32.2
t
40.0
0.40
7.2
8.545
1.54
13.8
2.8
15.3
35.0
19.1
34.2
t
38.9
0.40
7.3
6.310
1.09
6.3
2.9
19.9
24.8
13.4
36.0
t
42.7
0.32
7.5
6.935
0.98
5.9
2.5
20.6
25.3
14.0
35.7
t
43.8
0.32
7.6
5.970
0.33
8.1
6.5
20.6
30.1
19.8
41.4
0.08
54.4
0.36
7.6
5.370
0.36
8.0
4.6
19.2
28.9
18.4
38.6
0.08
51.4
0.36
7.7
4.930
0.26
5.4
4.0
18.4
22.6
11.3
39.5
0.16
48.9
0.42
7.6
6.725
0.30
5.2
4.0
18.6
22.6
12.2
40.0
0.12
45.0
0.41
7.8
I/
Values included ammoniacal nitrogen. For the period 1965-1967, values are underestimated due to
loss of undetermined amounts of ammoniacal nitrogen during analysis. Method of analysis changed
in 1968.
t Values not determined.
-------
Table 2. Continued.
1968 1969 1970
Constituent
Phosphorus
MBAS
Nitrate -N
Organic -N
Anmoniacal-N
Potassium
Calcium
Magnesium
Sodium
Manganese
Chloride
Boron
pH
1
5,345
0.50
4.7
2.9
15.7
16.7-
20.9
10.6
37.4
0.36
50.6
0.38
7.6
2
7.105
0.57
4.2
3.8
14.6
17.1
20.2
10.4
40.8
0.18
41.2
0.40
7.7
1
Concentration
4.675
0.57
5.8
7.8
11.4
15.2
34.6
17.4
51.5
0.12
60.6
0.34
7.8
2
Cmg/1)
6.560
0.54
5.1
4.8
12.8
13.8
32.0
16.3
52.8
0.10
44.4
0.38
7.9
1
4.265
0.44
5.8
3.3
5.3
13.5
29.8
14.3
34.3
0.14
48.1
0.29
7.9
2
4.135
0.44
4.9
4.1
6.3
13.7
24.2
11.8
32.7
0.11
45.0
0.29
8.0
-------
renovation for the nitrogen fractions will be discussed in terms of
the limiting concentration of 10 mg. NO--N per liter being exceeded
or not.
Since phosphorus and nitrogen are the two key eutrophic elements
most of the discussion in this paper will be focused on them. Table
3 shows the mean annual concentration of phosphorus in the applied
effluent and at the 6, 24 and 48 inch depths in the corn rotation
area from 1965 through 1970. The Duncan's separations shown are
between treatments within years and within depths. The wastewater
treatments began in 1963 but suction lysimeter samples for a complete
season were not obtained until 1965. These results show that on the
wastewater treated areas P concentration decreases drastically
between the upper six inches and the 24-inch depth, remains essen-
tially constant at the 24 and 48-inch depths, does not differ or is
erratically different from the control area at the deeper positions
but is significantly greater than the control (P = 0.01) at the six-
inch depth on the two-inch per week wastewater area each year begin-
ning in 1965. Differences between the control and 1-inch per week
area were generally not significant at the 6-inch depth.
For the 2-inch treatment the minimum decrease in concentration
at the 6-inch depth was 91 percent in 1967 and the maximum was 98
percent in 1965. On the 1-inch treatment area the minimum decrease
at the 6-inch depth was 97.1 percent in 1967 and the maximum was
99.1 percent in 1965. In 1970 the decrease was 96.7 percent for the
2-inch treatment and 98.4 percent for the 1-inch treatment at the
six-inch depth. At the 48-inch depth decrease in concentration
ranged from 98.1 percent to 99.6 percent for the 2-inch treatment
and from 98.6 to 99.8 percent for the 1-inch treatment. The data
indicate that phosphorus is not leaking out of the soil profile
into the groundwater at a higher concentration from the wastewater
treated area than from the control and that excellent removals of
phosphorus are continuing through the eighth year of treatment on
the com rotation area. A more detailed description of the phos-
phorus retention mechanisms is given in an unpublished Ph.D. thesis
(Edwards, 1968) and in the chapter by Hook, Kardos and Sopper (1973).
The reed canarygrass area, which is on the same soil type and
has been receiving two inches of effluent weekly, year around, since
1964, and hence almost twice as much phosphorus annually as the corn
rotation area, is much more effective in removing phosphorus.
Detailed phosphorus data for the reed canarygrass area are in Table 4.
The mean annual phosphorus concentrations at each depth were not signi-
ficantly different from year to year. Through 1970, the reed canary-
grass area had received 180 inches more wastewater than the corn
rotation area but lysimeter concentration at the six inch depth was
only 0.186 mg/1 compared to 0.557 mg/1 in the corn area.
135
-------
Table 3. Mean Annual Concentration (mg/1) of Phosphorus in Suction Lysimeter Samples at Three
Depths in Corn Rotation Plots Receiving Various Levels of Wastewater. 1965-70.
Depth
in
Tr> pVlP c
X11W11WO
6
24
48
0.
0.
0.
0
OSSa**-/
025a**
032b**
1965
1
0.047a
0.020a
0.016a
1968
1966
Wastewater Application -
2
O.llSb
0.044b
0.022ab
0
0.044a**
0.045N.S.
0.045b*
1
0.077a
0.036
0.028a
1969
Wastewater Application -
6
24
48
0.
0.
0.
0
035a**
048a*
041N.S.
1
0.160a
0.063ab
0.052
2
0.586b
0.078b
0.060
0
0.022a**
0.079N.S.
0.066N.S.
1
0.073a
0.046
0.066
Inches
2
0.269b
0.055
0.036ab
Inches
2
O.SSTb
0.058
0.070
Per
0
0
0
Per
0
0
0
Week
0
.046a**
. 39a**
. 039a**
Week
0
. 042a**
.054N.S.
.034a**
1967
1
0.149a
0.039a
0.030a
1970
1
0.060a
0.064
0.052ab
2
0.571b
0.086b
0.054b
2
0.138b
0.094
0.075b
—' The Duncan's separations are between Wastewater treatments within depths and within years.
** = P(0.01), * = P(0.05), N.S. = not significant
-------
Table 4. 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 1970.
Lysimeter
Depth
inches
6
24
48
1966
1967
1968
concentration -
0.164
0.091
0.055
0.128
0.110
0.053
0.218
0.120
0.052
1969
mg/1
0.186
0.089
0.035
1970
0.161
0.067
0.038
Wastewater 7.690 7.695 8.450 4.185 3.490
Comparative data for phosphorus in the forest areas are given in
Table 5. The irrigation programs and soil types for these areas are
given in Table 1. Although there are variations in time of initiation
of wastewater irrigation and total irrigation load on the various areas,
in 1970 phosphorus concentration at the 48-inch depth on the Morrison
sandy soil area is substantially higher than on the finer textured
Hublersburg soil areas. The detailed data in Table 5 show some erratic
fluctuations at any one depth from year to year but the grand average
over years show the greatest effect of wastewater additions on the
phosphorus concentration in the 6-inch zone, with diminishing effect
in the deeper zones.
Although the concentrations of phosphorus in the percolating soil
water was adequately small on all of the sites the same cannot be said
for nitrate-nitrogen. Table 6 and 7 indicate that the corn rotation
area held nitrate-nitrogen levels below the recommended Public Health
Service limit for drinking water, 10 mg NC^-N per liter, on the control
and 1-inch per week treatments quite well. However, at the 2-inch per
week level the mean annual concentration remained below the limit only
when grass-legume hays occupied from 28 to 68 percent of the site in
1965 through 1968. In 1969 and 1970 when the entire site was occupied
by corn the mean annual concentration exceeded the Public Health
Service limit. On the reed canarygrass area where more than twice as
much nitrogen was added annually in the year-around 2-inch application
the mean annual NOg-N concentration remained well below the Public
Health Service limit.
The nitrate data for the forested areas are given in Table 8. It
is clear that the forested areas can handle a 1-inch per week applica-
tion without having the mean annual concentration of the 48-inch depth
exceed the Public Health Service limit. However, when 2 inches were
137
-------
Table 5. Mean Annual Concentration (mg/1) of Phosphorus in Suction
Lysimeter Samples at Three Depths in Forest Areas Receiving
Various Levels of Wastewater During the Period 1965 to 1970.
VQQ-V
I Cell
1965
1966
1967
1968
1969
1970
Ave.
6 -Inch Depth
inches per week
0.
0.
0.
0.
0.
0.
0.
0
450
157
065
024
020
171
148
1
0.178
0.202
0.149
0.562
0.056
0.094
0
0
0
1
0
0
0.207 0
2
.335
.373
.242
.007
.261
.235
.409
Red Pine - Hublersburg Soil
24-Inch Depth 48-Inch Depth
inches per week
012
0.190 0.517
0.064 0.024 0.049
0.040 0.108 0.072
0.013 0.253 0.109
0.040 0.068 0.040
0.076 0.053 0.065
0.047 0.116 0.142
0.
0.
0.
0.
0.
0.
0.
inches
0
040 0
043 0
053 0
075 0
010 0
065 0
048 0
per
1
.300
.134
.092
.089
.064
.076
.126
week
0.
0.
0.
0.
0.
0.
0.
2
400
143
031
044
037
070
121
Hardwood - Hublersburg Soil
6 -Inch
Depth
inches per week
1965
1966
1967
1968
1969
1970
Ave.
0
0
0
0
0
0
0
0
.065
.048
.053
.064
.023
.047
.050
_
0.
0.
0.
0.
0.
0.
1
-
429
068
166
212
244
224
24- Inch Depth
inches per week
0 1
0.010 0.390
0.034 0.077
0.030 0.078
0.044 0.388
0.025 0.065
0.046 0.087
0.032 0.181
48- Inch Depth
inches
0
0.050
0.037
0.044
0.106
0.072
0.033
0.057
per
0.
0.
0.
0.
0.
0.
0.
week
1
250
043
077
222
047
143
130
138
-------
Table 5. Continued.
Old Field - Hublersburg
6- Inch Depth 24- Inch Depth
Year
1965
1966
1967
1968
1969
1970
Ave.
Year
1966
1967
1968
1969
1970
inches per week
0 2
0.065
0.038 0.091
0.045 0.136
0.275
0.036 0.293
0.035 0.342
0.044 0.227
6 -Inch Depth
inches per week
0 2
0.076 0.255
0.049 0.113
0.020 0.452
0.031 0.319
0.052 0.277
inches per week
0 2
0.116
0.030 0.069
0.032 0.097
0.122 0.125
0.122
0.102 0.119
0.072 0.108
Soil
48 -Inch Depth
inches per week
0 2
0.460
0.030 0.140
0.039 0.068
0.040 0.053
0.051 0.098
0.042 0.114
0.040 0.156
Hardwood - Morrison Soil
24-Inch Depth 48-Inch Depth
inches per week
0 2
0.091 0.030
0.223 0.057
0.050 0.129
0.032 0.104
0.026 0.119
inches per week
0 2
0.059 0.042
0.068 0.063
0.071 0.116
0.059 0.137
0.051 0.209
Ave. 0.046 0.283 0.084 0.088 0.062 0.113
139
-------
Table 6. Mean Annual Concentration (mg/1) of Nit rate-Nitrogen in Suction Lysimeter Samples at
Three Depths in Corn Rotation Plots Receiving Various Levels of Wastewater During the
Period 1965 to 1960.
Depth
in
6
24
48
1965
Wastewater
6.
6.
5.
0
8N.S.
1N.S.
2a**
1
4.2
6.8
8.2b
2
4.7
7.7
9.7c
4
3
4
1966
Application -
0
.eb**-/
!3b**
.7a**
1
1.7a
1.8a
4.9a
Inches Per
2
5.0b
4. Ob
7. Ob
Week
0
l.la**
3.1b**
3.4a**
1967
1
2.4b
2.2a
3.8a
2
5.2c
6.6c
7.1b
1968 1969 1970
•£>•
0 Wastewater Application - Inches Per Week
6
24
48
12.
2.
4.
0
6N.S.
6a**
5a**
1
12.0
4.5b
5.8b
2
10.5
10. 6c
9.5c
14.
10.
9.
0
7N.S.
Ob**
4b**
1
11.9
5.3a
7.7a
2
17.3
14. Oc
13. 5c
0
9.6N.S.
7.3N.S.
10.3N.S.
1
8.5
6.0
8.9
2
6.5
8.1
10.9
—' The Duncan's separations are between wastewater treatments within depths and within years.
** = P(0.01); N.S. = non-significant.
-------
Table 7. 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 1970.
Lysimeter
Depth
inches
6
24
48
1966
1967
1968
concentration -
0.8N.S.
2.2N.S.
3. 7b*I/
0.6
1.5
3. Sab
0.7
1.8
3. lab
1969
mg/1
0.6
1.1
2.5a
1970
1.2
0.8
2.4a
— ' The Duncan's separations are between years within depths.
* - P(0.05), N.S. = non- significant
applied per week either in the April-Nov. period with red pine on the
Hublersburg soil or year-around with hardwoods on the Morrison soil the
N03-N concentration at the 48- inch depth rapidly exceeded the Public
Health Service limit. On the other hand, 2 inches of wastewater applied
weekly on the old field area in the April-Nov. period did not result in
excessive NOs-N values at the 48-inch depth.
The difference between the 2- inch red pine and 2 -inch old field
areas on the same soil type probably 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 annual 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 carbonaceous
material in the old field area may also promote a higher degree of
denitrification in this fine textured soil. The sandiness of the soil
on the 2 -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 resi-
dues.
The explanation above was serendipitously corroborated when the
2- 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 clear-
cutting in 1969 the area grew up to a dense cover of herbaceous vegeta-
tion similar to that on the irrigated old field area. A large mass of
141
-------
carbonaceous material was deposited on the surface that fall and in
1970 another dense cover of herbaceous vegetation was produced and the
mean annual concentration of N03-N dropped from a value of 24.2 mg
N03-N/1 in 1969 to a value of 8.3 mg N03-N/1 in 1970 and to 3.0 mg
N03-N/1 in 1971.
Further support for the importance of denitrification in decreas-
ing the inputs of nitrate to the groundwater was obtained in the data
from the Hardwood area on the Hublersburg soil which received four
inches of wastewater, weekly, in the April-Nov. period (Table 8). In
spite of doubling the nitrogen load, the N03-N concentration at 48
inches remained below 10 mg/1, probably because the larger hydraulic
load encouraged more denitrification.
Changes in concentration of other chemical constituents in the
wastewater have also been examined. For instance, on the corn rota-
tion area during 1970 the concentration in the applied wastewater was
greater than in the lysimeter samples at the 48-inch depth. By the
time the percolate reached the 48-inch depth some degree of renovation
was secured for all constituents. However, if one compares the con-
centrations in the control area with those in the wastewater treated
areas the pattern is not consistent. For example concentrations of K,
Ca and Mn were higher in the control area at 48 inches than in the
wastewater treated areas, while the reverse was true for Mg, Na, Cl, B
and total-N (N03-N + Org.-N + Nfy-N). It should be pointed out that
the control area did receive substantial amounts of K and Ca in the
commercial fertilizer that was applied to that area but not to the
wastewater areas. The greatest increase in concentration as a result
of the wastewater treatment occurred with Na and Cl. The sodium con-
centration increased almost 14-fold on the two-inch treatment compared
to the control and the chloride concentration increased to a value
almost 5 times that of the control. The largest relative decrease in
concentration from that in the wastewater occurred with potassium as
a 15-fold decrease from 13.7 mg/1 in the wastewater to 0.9 mg/1 at the
48-inch depth in the 2-inch wastewater area.
Boron and manganese were substantially decreased in concentration
from that in the wastewater, boron decreasing from 0.29 to 0.09 mg/1
and manganese decreasing from 0.11 to 0.03 mg/1. Both of these concen-
trations as well as those of the other constituents, except nitrate-
nitrogen, are well below the recommended limits for drinking water.
The nit rate-nitrogen, which constitutes about 83 percent of the total
nitrogen in the percolate on the corn area can be substantially de-
creased below the N03-N limit by using a perennial grass as the vegeta-
tive cover rather than an annual crop such as corn. These nitrogen
relationships were discussed earlier and the problem of handling the
excess nitrogen should not be an unsurmountable one.
142
-------
Table 8. Mean Annual Concentration (mg/1) of Nitrate-Nitrogen in
Suction Lysimeter Samples at Three Depths in Forest Areas
Receiving Various Levels of Wastewater. 1965-1970
6 -Inch Depth
Year
1965
1966
1967
1968
1969
1970
Ave.
Year
1965
1966
1967
1968
1969
1970
Ave,
inches per week
0 1
0.2 1.
0.1 1.
0.9 6.
0.5 18.
0.1 17.
<1 11.
0.3 9.
7
5
9
7
6
0
6
6 -Inch
inches
0
0.1
0.1
0.4
0.4
0.4
<1
0.3
2
9.2
26.8
9.6
21.8
10.5
4.8
13.8
Depth
Red Pine - Hublersburg
24 -Inch Depth
inches per week
0
-- 0
0.2 0
0.4 5
0.2 6
0.2 9
1.7 5
0.5 4
Hardwood -
1
.4
.2
.1
.1
.0
.5
.4
2
10.7
14.6
10.6
17.6
19.6
3.3
12.7
Hublersburg
24- Inch
Depth
per week inches per week
1
1.0
3.3
13.3
10.9
6.8
9.5
7.5
0
—
0.1
0.4
0.2
0.3
<1
0.3
1
0.2
2.1
5.4
10.0
4.9
4.7
4.6
Soil
48 -Inch Depth
inches per
0
0.9
0.1
0.9
0.9
0.2
<1
0.6
Soil
1
2.
2.
1.
2.
4.
5.
3.
2
1
7
7
2
3
0
48 -Inch
inches
0
0
0
0
0
0
--
.1
.3
.1
.1
<1
.2
week
2
3.
9.
13.
19.
24.
8.
13.
9
3
8
9
2
3
2
Depth
per week
1
0.0
0.2
1.4
8.0
7.2
5.0
3.6
143
-------
Table 8. Continued.
Year
1965
1966
1967
1968
1969
1970
Ave.
6- Inch
Old Field - Hublersburg Soil
Depth 24- Inch Depth 48 -Inch Depth
inches per
0
0
0
0
0
0
0
.1
.1
.4
.0
.4
<1
.3
5
4
4
4
7
5
5
week
2
.1
.3
.6
.8
.3
.2
.2
inches
0
0
0
0
0
1
0
0
.1
.4
.4
.2
.4
.0
.4
per week inches per week
2
8.4
7.5
12.0
4.9
8.3
2.4
7.3
Hardwood - Morrison
Year
1966
1967
1968
1969
1970
Ave.
6 -Inch
Depth
inches per
0
0
0
1
0
0
.2
--
.1
.4
.1
.5
12
16
22
17
21
17
week
2
.5
.9
.3
.0
.0
.9
24 -Inch Depth
inches
0
0
0
0
0
0
.5
.5
.2
.1
<1
.3
per week
2
14.9
20.4
26.0
24.4
34.8
24.1
Hardwood - Hublersburg
6 -Inch Depth
Year
1965
1966
1967
1968
Ave.
inches
0
0.1
0.1
0.4
0.4
0.3
per week
4
7.
11.
8.
8.
9.
3
1
6
8
0
24 -Inch Depth
inches
0
_ _
0.1
0.4
0.2
0.2
per
week
4
4.2
9.3
5.1
3.2
5.5
48 -Inch
0
0
0
0
0
0
Soil
0
.3
.1
.3
.2
.2
<1
.2
2
8.
5.
6.
3.
2.
3.
4.
0
0
1
7
3
5
8
48 -Inch Depth
inches per week
0
1
0
0
1
0
Soil
Depth
0
.1
.4
.1
.3
.0
.6
2
10.
19.
25.
23.
42.
24.
6
2
9
7
8
4
72 -Inch Depth
inches per week
0
__
0.1
0.3
0.1
- 0.2
4
2.3
9.1
3.4
0.9
3.9
inches per week
0
—
--
--
--
4
5.2
9.5
8.3
8.2
7.8
144
-------
The data allow one to conclude that with appropriate management
of nitrogen loads to maximize utilization by the vegetation and with
hydraulic loads adjusted to the soil site to maximize denitrification
it should be possible to recharge water of drinking quality into the
aquifer below a wastewater disposal site.
ACDKNOWLEDGEMENT
Research reported here is part of the program of the Waste Water
Renovation and Conservation Project of the Institute for Research on
Land and Water Resources, and Hatch Projects No. 1481 and 1809 of the
Agricultural Experiment Station, The Pennsylvania State University,
University Park, Pennsylvania.
Portions of this research were supported by funds from Demonstra-
tion Project Grant WPD 95-01 received initially from the Division of
Water Supply and Pollution Control of the United States Department of
Health, Education, and Welfare and subsequently from the Federal Water
Pollution Control Administration, United States Department of the
interior. Partial support was also provided by the Office of Water
Resources Research, United States Department of the Interior, as auth-
orized under the Water Resources Research Act of 1964, Public Law
88-379.
4CES
Edwards, Ivor K. The Renovation of Sewage Plant Effluent by the Soil
and by Agronomic Crops. Ph.D. Thesis in Agronomy. 174pp. Sept.
1968.
Hook, James E., L. T. Kardos and W. E. Sopper. 1973. Effect of Land
Disposal of Wastewaters on Soil Phosphorus Relations. Proceedings
of Symposium on Recycling Treated Municipal Wastewater and Sludge
Through Forest and Cropland. The Pennsylvania State University
Press.
Parizek, R. R., L. T. Kardos, W. E. Sopper, E. A. Myers, D. E. Davis,
M. A. Farrell and J. B. Nesbitt. 1967* Waste Water Renovation
and Conservation. Penn State Studies No. 23, 71pp. The
Pennsylvania State University, University Park, Pennsylvania.
145
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RENOVATING SECONDARY EFFLUENT BY GROUNDWATER RECHARGE
WITH INFILTRATION BASINS
Herman Bouwer
U. S. Water Conservation Laboratory
Agriculture Research Service, USDA
The Salt River Valley in Central Arizona is changing from
a predominantly agricultural to a predominantly urban valley.
Groundwater currently supplies about one-third of the municipal
and agricultural water needs in the area of the Salt River Pro-
ject, which is the main irrigation district in the Valley. The
resulting depletion of the groundwater can be reduced if the sewage
effluent produced by the increasing population (presently about
one million) can be reused. The principal contenders for the sew-
age effluent would be irrigated agriculture and recreation (parks,
golf courses, and lakes). Certain industrial applications may
also be possible, but reuse for drinking water is still far off
(Long and Bell, 1972).
Unrestricted use of sewage effluent for recreational lakes
and irrigation requires tertiary treatment. A promising tech-
nique for such treatment in the Salt River Valley would be by
groundwater recharge, with spreading basins in the Salt River
bed. This normally dry bed traverses the Valley from east to
west, attains a width of one-half to one mile, and consists
mostly of a loamy sand top layer underlain by coarse sand and
gravel strata. The groundwater table is at a depth of 10 to
50 feet in the western part of the Valley. A chain of infil-
tration basins could be constructed on each side of the river
bed. After infiltration, the sewage water would move to the
center of the river bed where it would be pumped from a series
of wells.
Because the performance of a land-filtration system depends
so much on the local conditions of climate, soil, and groundwater,
a pilot system should precede any large-scale development. For
the Salt River bed, such a system was installed in 1967. The
study is in cooperation with the Salt River Project, which re-
ceived a demonstration grant from the Environmental Protection
Agency for partial support of the first three years of study.
The findings obtained and their use in the design of a large-
scale system will be presented in the following sections.
146
-------
EXPERIMENTAL PROJECT
Description of System
The experimental system, called the Flushing Meadows Project,
is located in the Salt River bed west of Phoenix, about 1.5 miles
west of 91st Avenue. The project contains six parallel infiltra-
tion basins of 20 by 700 feet each and 20 feet apart, and a number
of observation wells. Secondary effluent from the 91st Avenue
sewage treatment plant (activated sludge process) is pumped into
the basins from the effluent channel on the north side of the
project.
The first 50 feet of each infiltration basin were made into
a sedimentation pond by excavating the bottom of the basin and
constructing a gravel dam 50 feet from the inlet. Constant water
depth in each basin is maintained by an overflow structure at
the lower end of the basin. Infiltration rates in the basins
are calculated from the inflow at the upper end and the outflow
at the lower end measured with critical depth flumes (Replogle,
1971).
The soil profile beneath the basins consists of about 3 feet
of fine, loamy sand (saturated hydraulic conductivity about 4 feet/
day) underlain by coarse sand and gravel layers to a depth of
about 240 feet, where a clay layer begins. The profile has been
described in detail (Bouwer, 1970). The static water table is at
a depth of about 10 feet. The observation wells are 20 feet deep,
with the exception of the East Center Well (ECW), which is 30
feet deep, and the West Center Well (WCW), which is 100 feet
deep. All wells are cased with non-perforated steel pipe, open at
the bottom.
Infiltration Rates and Flooding Schedules
The infiltration rates generally ranged between 2 and 3 feet
per day at the beginning to between 1 and 2 feet per day at the
end of an inundation period, at a water depth of 1 foot. The
decrease in infiltration was due to clogging of the surface layer
of the soil and it was essentially linear with time. Drying the
basins restored the infiltration rate. The infiltration recovery
during dry-up was S-shaped, and essentially complete,recovery of
the infiltration rate was generally obtained after 10 days of
drying in the summer and 20 days in the winter.
Maximum long term "hydraulic loading" was obtained with
flooding periods of 2 to 3 weeks, alternated with dry periods of
about 10 days in summer and 20 days in winter. With this schedule,
an annual infiltration of 400 feet has been obtained. Regular
147
-------
drying of the basins was also necessary to provide oxygen in the
soil for BOD removal and nitrification of ammonium.
Suspended solids had a significant effect on infiltration
rates. In the summer and fall, the suspended solids content was
generally in the 10 to 20 mg/1 range, which was acceptable for
infiltration. In the winter and spring, however, the suspended
solids content was often in the 50 to 100 mg/1 range. This caused
a build-up of sludge in the basins, which was removed each year
in late spring or early summer by "shaving" the basins with a
front-end loader. Best infiltration results were obtained if
the suspended solids content was less than 10 mg/1 (Rice,
1972).
Infiltration rates in basins with an established grass cover
(Bermudagrass) were about 251 higher, and those in a gravel-
covered basin (2 inches of concrete sand topped by 4 inches of
3/8-inch rock) were about 50% lower, than those in a bare soil
basin, when the soil variability between the basins was taken
into account. In the spring, however, short flooding periods had
to be used for the grassed basins to allow the grass to grow to
a mature stand. During this sequence of short flooding periods,
the infiltration amounts were less than those in the bare soil
basin where flooding periods of 2 to 3 weeks could be used for the
entire year. Moreover, the increased infiltration obtained for
a complete grass cover could also have been obtained in the basins
without vegetation by increasing the water depth. Thus, over a
long period, non-vegetated basins can yield similar or even higher
infiltration rates than vegetated basins.
Vegetation may be desirable where the wastewater is applied
with sprinklers to protect the soil surface against the impact of
the drops. Also, vegetated basins may remove more nitrogen from
the effluent than non-vegetated basins (see section on Nitrogen).
The low infiltration rates in the gravel-covered basin are at-
tributed to accumulation of solids at the surface of
the underlying soil, and to poor drying of this soil during dry
periods caused by a mulching effect of the gravel layer.
Water Table Response
The static depth of the groundwater table was about 10 feet
below the bottom of the infiltration basins. The water table
beneath the basins rose during infiltration and reached a pseudo-
equilibrium position which, in the center, was about 2 to 4
feet (depending on the infiltration rates) above the static water
table level. During dry periods, the water table receded to its
static level.
148
-------
Based on the assumption that the sand and gravel layers of
the aquifer formed a uniform anisotropic medium, the hydraulic
conductivity of the aquifer was evaluated as 282 feet/day
horizontally and 17.6 feet/day vertically. These values were
obtained with an electrical resistance network analog from the
response of the water levels in the East Center Well and the West
Center Well to infiltration, and they agreed with directional
hydraulic conductivity data obtained from permeability tests on
the observation wells (Bouwer, 1970).
Water Quality Improvement
Quality parameters of the secondary effluent and the water
pumped from the 30-foot-deep East Center Well (ECW), mostly
obtained in 1971, are shown in Table 1. The effluent was sampled
Table 1. General Range of Quality Parameters of Secondary
Sewage Effluent and Renovated Water from East
Center Well
Constituent Effluent East Center Well
BOD
COD
TOG
Org.-N
N03-N
N07-N
Mtf-N
POj-P
F
B
Cu
Zn
Cd
Pb
Total salts
PH
Fecal coliforms per 100 ml
mg/1
10-20
30-60
10-25
2-6
0-1
0-3
20-40
7-12
3-5
0.7-0.9
0.1
0.2
0.008
0.08
1,000-1,200
7.7-8.1
105-10°
mg/1
0-1
10-20
1-7
0.3-0.7
0.1-50
0-1
5-20
4-8
2-2.5
0.7-0.9
0.02
0.1
0.007
0.07
1,000-1,200
6.9-7.2
0-100
continuously for 24-hour periods. Grab samples were obtained
almost daily from ECW. The water obtained from ECW is effluent
water that infiltrated in basins 3 and 4, then moved through about
149
-------
6 feet of unsaturated soil to the water table, after which it
traveled about 30 feet below the water table to the intake of
the well. The underground detention time of EQV-water was about
5 to 10 days, depending on the infiltration rate in the basins.
Oxygen demand. The BOD of the renovated water from ECW was
essentially zero (Table 1). The COD of ECW-water was in the 10-
to 20-mg/l range, which was about the same as the COD of the native
groundwater in the area. The total organic carbon content (TOG)
of the renovated water averaged about 4 mg/1, indicating some
residual organic matter.
Nitrogen. The nitrogen in the effluent was mostly in the
ammonium form (Table 1). Total nitrogen levels in the effluent
ranged from around 25 mg/1 in the summer to around 35 mg/1 in the
winter. The form and concentration of the nitrogen in the reno-
vated water depended on the length of the inundation periods of
the basins and on whether the basins were vegetated.
When short, frequent flooding periods were used for the basins
(i.e. 2 days wet-2 days dry), the oxygen levels in the soil were
sufficiently high for complete nitrification of the ammonium. In
that case, the renovated water from the wells contained NH.-N levels
of 1-5 mg/1 and N03-N levels of 20-30 mg/1.
If medium inundation periods were used (i.e. 2 weeks wet-2
weeks dry), NOj-N levels were close to zero in the renovated water,
except for NOyN peaks which occurred a few days after the start
of each new inundation. These peaks were due to the arrival of
effluent water that was held as capillary water in the soil during
the preceding dry period. Because of the aerobic conditions in the
upper layers of the soil during drying, ammonium adsorbed by the
clay and organic matter during inundation, plus the ammonium in the
capillary effluent water itself, could be converted to nitrate.
When the basins were flooded again, this nitrate-rich effluent water
was then pushed down by the newly infiltrated water, and when it
arrived at a well caused a NO^-peak in the water samples from that
well. The arrival time of the NOj-peak at ECW ranged between 5 and
10 days, depending on the infiltration rate in basins 3 and 4.
If very long inundation periods were used (i.e. several months),
the nitrogen can be expected to remain in the ammonium form as the
effluent moves through the soil. This has not been tested in the
field system, but it was observed in parallel laboratory studies
where columns filled with soil from the infiltration basins were
flooded with the same secondary effluent (Lance and Whisler, 1972).
When sequences of medium inundation periods were first used
in 1968, the Mfy-N concentration in the renovated water was in the
2-3 mg/1 range. Thus, after the passage of the N03-peak, the total
nitrogen level in the renovated water was 90% less than that in the
150
-------
sewage effluent. However, continued use of medium inundation
periods caused a gradual increase in the NHL-N level in the reno-
vated water. In 1969, for example, the NH|-N level in EC1V water
increased from 4 mg/1 in January to about 10 mg/1 in July. Then
it gradually dropped to 4 mg/1 in November, and increased again to
reach about 15 mg/1 in June 1970. After that, the NHU-N level in
the water from ECW decreased to 7.5 mg/1 in November 1970. In 1970,
the total-N level in the renovated water after the passage of the
NOj-peak was only 30% to 60% less than that in the sewage effluent.
The gradual increase in the Ntfy-N level was probably due to
the application of more ammonium during flooding than could be
nitrified during drying, causing the cation exchange complex in
the soil to remain essentially saturated with NH.. The limiting
factor is probably the amount of oxygen entering the soil during
drying (Lance et al., 1972). During the summer months, higher
temperatures and" Better drying of the soil may cause a temporary
increase in the nitrifieir activity. This could explain the de-
crease in the NH^-N concentration of the renovated water from
May until December.
The tendency of the Mty-level in the renovated water to
gradually increase with continued use of 2-3 week flooding periods
was reversed by changing to a sequence of short, frequent floodings
(i.e. 2 days wet-5 days dry). This was done in 1971 for basins
1, 2, 5, and 6, while basins 3 and 4 were continued to be flooded
with 2-3 week periods. While the NH.-N level in the renovated
water below basins 3 and 4 stayed at a plateau of about 18 mg/1 for
most of 1971, the Mty-N levels below basins 1, 2, 5, and 6 gradually
decreased to about 5 mg/1 at .the end of 1971. During the first few
months of 1971, when short inundation periods were used for basins
1, 2, 5, and 6, the renovated water below basins 1 and 2, which were
not vegetated, contained much higher NOj-N levels than the renovated
water below basins 5 and 6, which were covered by native grasses
(mainly Mexican sprangletop and barnyard grass) and bermudagrass.
This NOj-N was probably due to nitrification of ammonium stored in
the soil during the preceding sequences of medium flooding periods.
The lower N03~N releases from the vegetated basins could be attri-
buted to increased denitrification in the root zone, or to decreased
nitrification which would cause the ammonium to remain adsorbed to
the clay and organic matter.
With high-rate land disposal systems, such as the Flushing
Meadows Project with loading rates of 300 to 400 feet per year,
the nitrogen loading is so high (24,000 to 32,000 pounds per acre
per year at Flushing Meadows), that crop uptake of nitrogen is
insignificant as a removal process. Some nitrogen can be stored
in tiie soil by adsorption of ammonium to clay and organic matter,
fixation in microbial tissue, etc., but this is only temporary.
Consistent nitrogen removal can be obtained mainly by denitrifi-
cation. This requires the presence of nitrate and organic carbon
151
-------
under anaerobic conditions. If nitrogen removal from the effluent
water is desired, the system should be managed so as to create
conditions that promote denitrification.
For example, the pattern of nitrogen removal with sequences
of 2-3 week flooding periods is probably due to denitrification.
During dry-up, and probably also during the initial stages of in-
undation, the upper 3 feet of soil are aerobic and the ammonium
nitrogen in the capillary water and that adsorbed on the clay and
organic matter can be nitrified. Some of the nitrate thus formed
may move into micro-anaerobic pockets in the soil, where denitri-
fication can occur. Also, when flooding is resumed, the nitrates
may mix with the incoming sewage effluent and become denitrified
in anaerobic zones. When all nitrates are flushed out and oxygen
is depleted, the nitrogen in the effluent water will probably stay
in the ammonium form and can be adsorbed by the clay and organic
matter, after which it will be nitrified during the following dry-
up period.
The overall nitrogen removal is difficult to predict because
the volumes represented by the samples from ECW are not known.
However, the N levels in the renovated water from the wells outside
the basin area, where the N03 peaks are not as distinct indicate
that total nitrogen removals of around 30% can be obtained with
medium flooding periods (2 weeks wet-2 weeks dry). This agrees
with results from laboratory studies using soil columns, where a
complete nitrogen balance could be developed for the system (Lance
and Whisler, 1972).
There is some evidence that vegetation had a beneficial effect
on denitrification. For example, in 1968, the N03~N levels after
the passage of the NC>3 peaks were about 6 mg/1 in the renovated
.water below the bare-soil basins, but less than 0.5 mg/1 in the
renovated water below the basins with a mature stand of bermuda-
grass. Also, the grassed basins released much less nitrate than
bare-soil basins when, after 3 years of using primarily 2-3 week
flooding periods, the schedule was changed to a sequence of 2 days
flooding-5 days dry to lower the ammonium level in the renovated
water. Direct uptake of N by the crop could not account for the
difference in nitrate levels in the renovated water. The beneficial
effects of vegetation on denitrification are probably due to the
organic carbon exuded by live roots and that returned to the soil
by decaying roots (which supplied energy for the denitrifying
organisms) and to the more anaerobic environments due to oxygen
uptake by the root system (Woldendorp et^al,, 1965). More research
is needed on the effect of vegetation on denitrification and the
system management needed to obtain maximum nitrogen removal.
Phosphate. The PO^-P levels in the secondary sewage effluent
averaged about 10 mg/1 in 1970 and 1971. The PCty-P concentrations
152
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in the renovated water from ECW were low when the project was first
started, but gradually increased to about the 5 mg/1 level, where it
has remained for the last 2 years. The renovated water yielded by
the "outlying" wells 1 and 8 had lower PCty-P levels. The main mech-
anism for P-removal is probably precipitation of calcium-phosphate
compounds, such as apatite, and precipitation of magnesium ammonium
phosphate. Analysis of the top soil from the infiltration basins
with an electron microprobe indicated phosphorus-rich clumps and
coatings of soil particles. Phosphate-fixing materials, such as
iron and aluminum oxides, are not present in large quantities in the
sands and gravels of the Salt River bed.
Fluoride. The fluoride content was reduced from about 4 mg/1
in the~efflueht to about 2 mg/1 in the renovated water from ECW.
Like the phosphates, the water from the outlying wells was lower in
fluoride. The removal of fluoride paralleled that of phosphate,
suggesting the formation of fluorapatites as a probable mechanism
for its decrease.
Boron. The boron concentration in the effluent gradually
increased1 from about 0.4 mg/1 in 1968 to about 0.9 mg/1 in 1971.
Boron is not removed as the effluent moves through the sands and
gravels of the Salt River bed (Table 1).
Metals. Metal analyses were carried out in the fall of 1971
on six samples taken bi-weekly over a 2-month period. The con-
centrations of copper and zinc in the renovated water from ECW
were considerably less than those in the effluent, but the con-
centrations of lead and cadmium remained essentially unchanged
(Table 1). A combination of high pH and aerobic environment
apparently favors immobilization of metallic ions in the soil.
Total salts. The concentration of total dissolved salts in
the effluent was generally in the 1000-1200 mg/1 range in the efflu-
ent. The salt concentration in the renovated water was slightly
higher, as a result of evaporation from the infiltration basins.
The annual evaporation from a free water surface in central Arizona
is about 6 feet. The evaporation at Flushing Meadows can be
expected to be slightly less, because evaporation from the soil is
reduced at the end of a dry period. When the annual evaporation is
about 5 feet and the annual infiltration is 350 feet, the salt content
of the renovated water can be expected to be about 1.4% higher than
that of the effluent.
The concentrations of the more important ions in the effluent
were as follows:
153
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Ion Concentration Ion Concentration
mg/1 mg/1
Na+ 200 HC03- 381
Ca++ 82 Cl" 213
Mg++ 36 S04-- 107
K+ 8 CCy- 0
p_H. The pH of the renovated water was about 7, which is one
unit less than that of the sewage effluent (Table 1). This is
probably due to bacterial action in the soil, which produces carbon
dioxide and organic acids.
Fecal coliforms. Most of the reduction in fecal coliform
denisty (.Table I) occurred in the first 3 feet of travel through
the soil. This was determined by samples of effluent water taken
at different depths in the soil profile with ceramic cups to
which a vacuum was applied. For inundation periods of 2-3 weeks,
the fecal coliform density in the renovated water from ECW in-
creased after the start of a new flooding period, when newly
infiltrated water reached the well. The fecal coliform density
then decreased to low values (often zero) until the next flooding
period. The fecal coliform density for the outlying wells was
lower than for ECW, i.e. a general range of 0-10 per 100 ml for
well 7, and a complete absence of fecal coliforms for well 8.
OPERATIONAL SYSTEM
The infiltration studies at the Flushing Meadows Project
have shown that a full-scale operational system can be designed on
the basis of a hydraulic loading of about 300 feet per year. Thus,
one acre of infiltration basin can handle 300 acre-feet of sewage
effluent per year, or about 0.27 mgd. To renovate the total
present flow of around 80 mgd would thus require about 300 acres
of basins. The projected sewage flow for the year 2000 is some
300,000 acre-feet per year, which would require about 1,000
acres of basins.
Because of the many existing wells in the Salt River Valley,
the wastewater renovation system should be designed and operated
in such a way as to prevent the renovated water from moving into
the aquifer outside the system of infiltration basins and wells.
This can be achieved by locating the infiltration basins along
both edges of the river bed (which is about 0.5 mile wide) and
placing the wells for pumping the renovated water in the center
of the river bed. To insure that renovated water will not move into
the aquifer outside the river bed, the system should be operated to
154
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keep the water table below the outer edges of the basin areas at a
level equal to, or slightly below, the water table in the rest of
the aquifer. Thus, the renovated water should be pumped from the
wells at the same or a slightly higher rate than the infiltration
rates in the basins.
From the response of the water levels in the observation wells
to infiltration at the Flushing Meadows Project, the effective
transmissibility of the aquifer for recharge was evaluated by resis-
tance network analog and horizontal flow theory (Bouwer, 1970).
This transmissibility was then used in an analog study of the system
to predict water table positions and underground detention times for
various geometries. The results showed that the conditions in the
Salt River bed enable a system with underground detention times of
at least several weeks and underground travel distances of at least
several hundred feet (Bouwer, 1970). The quality of the renovated
water from the wells should be better than that shown in Table 1 for
the water from ECW, for which the underground detention time was
only about 1 week and the underground travel distance about 40 feet.
Thus, the large-scale operational system should yield renovated
water that can be used for unrestricted irrigation, primary contact
recreations, and certain industrial applications (Environmental
Protection Agency, 1968, and Arizona State Dept. of Health, 1972).
ECONOMIC ASPECTS
Preliminary estimates indicate that the total cost of putting
the sewage effluent into the ground and pumping it up as renovated
water with the system in the Salt River bed will be around $5 per
acre-foot (Buxton, 1969). The cost of in-plant tertiary treatment
to obtain renovated water of similar quality will be an order of
magnitude higher. Moreover, a significant part of the investment
for a land treatment system is in land. Since land values tend to
increase with time, an additional cost benefit can be obtained with
the sale or different use of the land once the infiltration system
has become obsolete. Wastewater renovation by groundwater recharge
is aesthetically more attractive to the public than in-plant treat-
ment. Also, land treatment systems are essentially 100% fail-safe.
ACKNOWLEDGMENTS
The author acknowledges the valuable contributions to this
project by E. D. Escarcega, J. C. Lance, and R. C. Rice of the U.S.
Water Conservation Laboratory. The cooperation of the Salt River
Project and its support of M. S. Riggs, who performed the water
analyses, are gratefully acknowledged. The metal analyses were
done by J. V. Lagerwerff of the U.S. Soils Laboratory, ARS-USDA,
in Beltsville, Md. P. R. Buseck of Arizona State University
performed the electron microprobe analyses of the soil.
155
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Arizona State Department of Health, Phoenix, Ariz. 1972. Rules
and regulations for reclaimed wastes.
Bouwer, Herman. 1970. Groundwater recharge design for renovating
wastewater. Jour. Sanitary Engr. Div., ASCE, vol. 96 SA1,
59-74.
Buxton, J. L. 1969. Determination of a cost for reclaiming sewage
effluent by groundwater recharge in Phoenix, Ariz. M.S.
thesis, Arizona State University, College of Engineering
Science.
Environmental Protection Agency, Washington, D.C. 1968. Water
quality criteria. Report of Natl. Tech. Adv. Comm. to
Secretary of Interior.
Lance, J. C. and F. D. Whisler. 1972. Nitrogen balance in soil
columns intermittently flooded with secondary sewage effluent.
Jour, of Environmental Quality 1, 180-186.
Lance, J. C., F. D. Whisler, and H. Bouwer. 1972. Oxygen
utilization in soils flooded with sewage water. Unpublished
report.
Long, W. N., and F. A. Bell. 1972. Health factors and reused
waters. Jour. Amer. Water Works Assoc. 64, 220-226.
Replogle, J. A. 1971. Critical-depth flumes for deteimining flow
in canals and natural channels. Amer. Soc. Agric. Engr.
Trans. 14, 428-433.
Rice, R. C. 1972. Soil clogging during infiltration with secondary
sewage effluent. Paper presented at Annual Meeting Amer.
Soc. Agric. Engr., Hot Springs, Ark.
Woldendorp, J. W., K. Dilz, and G. J. Kolenbrander. 1965. The
fate of fertilizer nitrogen on permanent grassland soils.
Proc. 1st General Meeting European Grassland Fed., 53-76.
156
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PHOSPHORUS AND NITRATE LEVELS IN GRQUNDWATER AS RELATED
TO IRRIGATION OF JACK PINE WITH SEWAGE EFFLUENT
Dean H. Urie
North Central Forest Experiment Station
Forest Service, USDA
In response to requests from municipalities to use forest
lands for sewage disposal sites, the North Central Forest Ex-
periment Station has begun research on the effects of sewage ef-
fluent on groundwater nutrient levels. This report covers results
from an initial test conducted near Cadillac, Michigan, under con-
ditions similar to those found on a site that has been selected
for sewage renovation near Traverse City, Michigan. The test
was conducted on a sand soil with a shallow water table where
groundwater contamination could be a serious hazard. The treat-
ment area was covered with a pole-sized jack pine (Pinus banksiana
Lamb.) stand having a sparse understory vegetation.
This exploratory test was conducted to gain background informa-
tion on the methods which could be used to conduct field tests of
sewage effluent renovation where only small volumes of effluent
are available.
Little research on sewage renovation in forests has been done
(Sopper, 1971). Reports by Rudolph and Oils (1955) and Rudolph
(1957) are perhaps most applicable to the study reported here, as
their tests of tree survival and growth under irrigation by cannery
wastewater was conducted on sand soils at Fremont, Michigan.
Groundwater under those tests was found to meet potable water
standards after 3 years of irrigation.
Irrigation with secondary effluent has resulted in a high
degree of phosphorus removal in loam and sandy loam soils under pine
and hardwood forests at The Pennsylvania State University. Nitrate
in soil water at 60-cm (24-inch) and 120-on (48-inch) depths has
increased during the study although no report of increases in
groundwater nitrate concentrations has yet been found. Water table
levels are approximately 60 m (200 feet) below the surface in
contrast to the shallow water tables in the study reported here.
Pure red pine (Pinus resinosa Ait.) removed less nitrate in The
Pennsylvania State University studies than hardwood and white
spruce forests. The pine plantation used for the test described
here was similarly expected to remove the smallest amount of
nitrogen of all forest types on the Traverse City project area.
157
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Despite the poor removal of nitrates on sand forest land, the
availability, low cost, high infiltration, and remoteness of such
soils have created a demand for them for sewage disposal with and
without the forest cover (Shaeffer, 1970; Urie, 1971).
METHODS OF STUDY
Secondary-treated municipal sewage effluent from the Cadillac,
Michigan, treatment plant was used to irrigate a small plot in a
35-year-old jack pine plantation. The plantation is located on a
Kalkaska loamy sand soil which is a Typic Haplorthod developed on
deep sand drift. During the test period, water table depth varied
from 1.3 m (4 feet) to 3 m (10 feet), which is shallower than normal
for Kalkaska sands on the proposed Traverse City disposal site.
The test site is located on the Cadillac District, Manistee National
Forest, NE 1/4, NW 1/4, Sec. 14, Selma Township, Wexford County,
Michigan.
The plantation had been thinned by removing every fourth row
in 1968. Slash from this cut was still present, with little
decomposition of twigs over 5 cm (1/5-inch) diameter. The residual
stand is about 10 m (40 feet) in height, with an average diameter
of 16 cm (6.3 inches). Ground cover is sparse except in the
cleared strips where a few hardwood seedlings have been established.
Lycopodium covered about 12 percent of the surface of the plot
prior to irrigation. Needle litter was 2.5 on (1 inch) in depth
before irrigation.
Observation wells were installed to depths of 1.5 m (5 feet)
below the water table on the irrigation t£st site. Measurements of
static water levels showed that the water table sloped toward
Pleasant Lake. Three wells were then installed within the irrigated
area. Two 1-1/4 inch diameter wells were driven to the level of
the lowest annual water table fluctuation. Well No. 1 was located
at the center of the irrigated plot and Well No. 2 was located on
the edge of the plot in the direction of groundwater flow, as
determined from the surrounding wells. A recorder was installed in
a 6-inch diameter well near the center of the irrigated plot. Pre-
vious groundwater studies in the area have shown that the annual
cycle of water table fluctuation experienced during the 1972 growing
season were similar to those occurring in 2 previous years.
A standard rain gage was installed in a nearby forest opening.
Water quality samples were removed from the two treatment wells
(No. 1 and No. 2) and two control wells (No. 3 and No. 4) using
a pitcher pimp. All wells were capped during irrigation.
158
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TREATMENT
Effluent Application
The effluent was trucked from the plant and temporarily stored
during the irrigation period. Irrigation began immediately upon
delivery. Sewage effluent was applied at an average rate of 64 mm
(2.5 inches) over a 10-hour period 1 day per week to an area averag-
ing 6.1 m (20 feet) in radius. Two applications were made during
November 1970. Treatments were renewed April 26, 1971, when the
ground was free of snow and frost, and continued until October 19,
1971. A total of 162 cm (64 inches) was applied during the 1971
growing season. Distribution of the single rotary sprinkler used
was checked with temporary gages. Application was relatively uniform
from 2 to 5 m (7 to 16 feet), except in tree shadows and splash zones.
Field Measurements
Water quality samples were removed from four wells about 12 hours
after irrigation ended. This timing coincided with the recharge
peak shown by the recording well.
A liter sample was collected from Wells 1, 2, 3, and 4 at each
sampling date. The samples were preserved with HgCl (10 mg/1) and
refrigerated. Storage did not exceed 30 days. Liter samples of
irrigated effluent were drawn from the temporary storage tank during
irrigation.
Rainfall during the week previous to each irrigation was measured
in the open using a standard 8 inch gage. The pattern of water table
levels in the center of the irrigated plot was deteimined from the
water level recorder record.
Lab Analyses
Chemical analyses of nitrate-N and total phosphorus in water
samples were performed by the Institute of Water Research, Michigan
State University, using standard Environmental Protection Agency
methods.
Additional measurements of ammonia-N and total Kjeldahl-N in
the sewage effluent from the Cadillac treatment plant were made from
samples collected during May and June 1972. These samples showed
similar nitrate-N and phosphorus levels to those measured during the
treatment period. The average level of total nitrogen was used to
estimate the total nitrogen applied during the test period.
159
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Soil samples were removed from 0- to 23-on (0- to 9-inch) and
23- to 53-cm (90 to 21-inch) layers in the irrigated plot and from
an equal number of points in the surrounding unirrigated control
area. Analyses of phosphorus and nitrate, as well as other
standard soil fertility tests were performed by the Michigan State
University Soil Testing Laboratory.
Suction lysimeters were installed at 61- and 122-cm depths
(24 and 48 inches) in September 1971. Samples of soil water were
removed on seven dates and analyzed for nitrate-N, ammonia-N, and
total phosphorus.
RESULTS
Phosphorus
The average concentration of phosphorus in the effluent was
7.52 mg/1 for the first 24 weeks of the 25-week season in 1972.
An excessively high value (58 mg/1) on the last treatment date
was associated with a temporary failure in the sewage treatment
process. This input boosted the average to 9.67 mg/1, a total
phosphorus loading of 141 pounds per acre.
The mean total phosphorus level in the two treatment wells
was 0.09 mg/1 for 25 sampling dates (Table 1). The mean level in
the control wells was 0.14 mg/1. There was no significant differ-
ence between the treatment and control wells. The two control wells
were in shallower water table situations, which may have caused a
small increase in average phosphorus content.
There was no evidence of phosphorus enrichment of the ground-
water. High levels in two wells on August 31 may have been due to
sampling errors as one treatment well and one control well were
anomalously high (0.72 and 0.99 mg/1, respectively).
Phosphorus levels in soil water at 60-on (24-inch) and 120-on
(48-inch) depths were sampled with tension lysimeters during
September and October. Total phosphorus in the soil water was
below 0.2 mg/1 in all samples.
Soil analyses were made on a rather gross basis. An increase
of 27 pounds per acre of total phosphorus was found in the 0- to
15-on(0- to 6-inch) layer of the irrigated plot (Table 2). Phos-
phorus contents of litter and foliage were not determined.
160
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Table 1. Total Phosphorus and Nitrate Levels in Groundwater
Samples Collected in the Pleasant Lake Study, 1971
Total Phosphorus
Nitrate-N
jjauc
11/10/70
11/11/70
11/18/70
4/27/71
4/29/71
5/ 4/71
5/11/71
5/18/71
5/25/71
6/ 2/71
6/ 8/71
6/15/71
6/22/71
6/29/71
11 7/71
7/13/71
7/19/71
7/26/71
8/ 2/71
8/10/71
8/17/71
8/31/71
9/14/71
9/28/71
10/20/71
Mean
Treatment
Mean
mg/1
0.04
.03
.04
.15
.14
.03
.03
.02
.02
.09
.06
.02
.08
.16
.26
.04
.03
.06
.10
.14
.18
.42
.04
.06
.06
.09
Control
Mean
mg/1
0.07
.13
.08
.18
.26
.24
.20
.20
.08
--
.12
.22
.12
.17
.29
.04
.08
.03
.04
.07
.10
.56
.04
.06
--
.14
Treatment
Mean
mg/1
0.16
.32
.22
.11
.16
.10
.06
.06
.14
.12
.12
.09
.18
.30
.36
.06
.06
.04
.03
.32
.23
.26
.93
.10
7.60
.48
Control
Mean
mg/1
0.63
.63
.57
.12
.08
.18
.28
.18
.18
--
.24
.28
.17
.40
.14
.10
.06
.02
.06
.11
.14
.26
.04
.05
--
.19
Nitrogen
Nitrate levels in the effluent were low, approximately the same
as in the groundwater public water supply source, 0.3 mg/1. Most
of the nitrogen was in ammonia and organic form, approximately
8.0 mg/1 and 2.9 mg/1, respectively. The total nitrogen applied
was about 170 pounds per acre.
161
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Groundwater samples were tested for nitrate during the entire
study. Tests for other forms of nitrogen were conducted only
during the final weeks of„ treatment. Definite increases in mean
nitrate levels appeared in September and continued through the
end of the irrigation. The test well on the downslope edge of the
treatment plot produced samples with the highest N03-N levels.
The highest NC^-N level of 14.3 mg/1 was measured on October 20,
10 days after the last irrigation.
Tension lysimeters at 60-on (24-inch) and 120-on (48-inch)
depths were used to collect samples during September and October
in which nitrate-N levels ranged from 25 to 30 mg/1. By mid-
November, nitrate levels at these depths in treatment and control
areas were below 5 mg/1.
Soil analyses showed increases of approximately 6 pounds
per acre of nitrate-N in the surface 6 inches (Table 2) on
October 20, 1971. After 10 days, no changes were found in deeper
Table 2. Nitrate-N and Total P in the Soils on the Irrigated
and Control Areas of the Pleasant Lake Study,
October 20, 1971
Total P Nitrate-N
Soil Depth Irrigated Control Irrigated Control
inches
0-6
6-12
12-21
Ibs/a
36
12
21
Ibs/a
9
8
18
Ibs/a
8
2
4
Ibs/a
2
2
4
soil layers despite the high soil-water nitrate level measured
on this date from suction lysimeters.
Vegetation Response
A comparison of 1971 annual growth on the 15 irrigated and
15 control jack pine was made in November. Increment borings
showed a mean annual radial growth of 0.14 on (0.055 inch) on
irrigated trees in comparison to 0.10 on (0.040 inch) on control
trees. Dominant trees showed greatest effects and the irrigated
trees had nearly twice the annual ring width of controls. The 1971
growing season was rather dry (May-September precipitation was
162
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95 mm (3.7 inches) below normal); thus, the supplemental water
may have been the main cause for the growth increase.
Subordinate vegetation increased in frequency due to
irrigation, mostly through survival of Prunus and Fraxinus seed-
lings. Several species of flowers and vegetables were introduced,
apparently from seeds contained in the sewage effluent.
DISCUSSION AND CONCLUSIONS
The single plot test described here illustrated that the
nitrates added in sewage effluent irrigation may reach shallow
water tables under sand-soil, forest conditions. Phosphorus
renovation was complete during the initial year. Public health
considerations may limit the permissible dosage levels in such
highly permeable soils. Further tests will be needed to determine
whether hardwood forest types or shrub-herb cover conditions may
be more satisfactory for sewage renovation purposes on sandy soils.
Alternative methods of cropping or volatilization of nitrogen may
be a necessary pretreatment before economic volumes of sewage
effluents can be renovated satisfactorily. Dilution of nitrate
levels during groundwater flow may be a satisfactory solution in
remote areas, with small sewage irrigation loads, and where do-
mestic water supplies are protected.
Experience with this single plot test has resulted in the
adoption of a different type of field test in locations where sewage
effluent must be trucked to the test site. Tests now in progress
utilize plots about 0.001 hectare in area using gravity methods
of application. Tension lysimeters (soil-water samplers) are
being used instead of wells to test the degree of renovation under
various treatments. These micro plots do not permit tests of
response of large trees to sewage treatments. Replicated tests
of renovation are possible with small volumes of effluent on a
variety of soils and understory vegetation types.
Rudolph, V. J. 1957. Further observations on irrigating trees with
cannery waste water. Mich. Agric. Expt. Sta. Q. Bull. 39,
416-423.
Rudolph, V. J., and R. E. Oils. 1955. Irrigating trees with
cannery waste water. Mich. Agric. Expt. Sta. Q. Bull. 37,
407-411.
Shaeffer, J. R. 1970. Reviving the Great Lakes. Saturday Rev.,
Nov. 9, 1970, p. 62-65.
Sopper, William E. 1971. Effects of trees and forests on neutralizing
wastes. In Trees and Forests in an Urbanizing Environment,
163
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Synposium on Urban Forestry, Amherst, Mass., p. 43-57.
Urie, Dean H. 1971. Opportunities and plans for sewage renova-
tion on forest and wildlands in Michigan. Mich. Acad. IV
(1), 115-124.
164
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RESTORATION OF ACID SPOIL BANKS
WITH TREATED SEWAGE SLUDGE
Terrence R. Lejcher and Samuel H. Kunkle
Shawnee National Forest, Eastern Region
Forest Service, USDA
In many areas where strip mining has occurred there is a
critical need for land reclamation, both to return wasteland to
productivity and to reduce water pollution problems. Strip mining
of coal often causes a significant degradation of water quality,
aquatic environment and riparian wildlife habitat (Udall, 1967).
In some cases, traditional strip mine reclamation techniques are
apparently ineffective for correcting water quality impacts
(Anderson, et al, 1972); therefore, new land reclamation tech-
niques are needed.
Studies at The Pennsylvania State University (Hunt, Sopper and
Kardos, 1971), and at other locations (Peterson and Gschwind, 1971),
indicate that the utilization of treated municipal wastes may offer
a potential technique for land reclamation in strip mined areas.
Simultaneously, many cities are faced with the question of sludge
disposal from their treatment plants. For example, Chicago is pro-
ducing over 900 metric tons per day (dry weight) of solids from its
sewage treatment plants. Disposal of the digested solids or
sludge includes the following alternatives and costs:
Dewatering and incineration $63/metric ton
Wet air oxidation $55/metric ton
Digestion and permanent lagoons $54/metric ton
Drying and sale as fertilizer $50/metric ton
Digestion, and reclamation of
strip mines $18/metric ton
Digestion, and reclamation of
farmlands $16/metric ton
In the case of Chicago, the sludge is disposed of primarily
by the first four processes above. The disadvantages of these
particular disposal methods include cost, air pollution, and the
scarcity of storage space. Sludge storage costs for the Metro-
politan Sanitary District of Greater Chicago are over 1.5 million
dollars per year (Dalton, et.aJL, 1968). On the other hand, sludge
disposal on strip mined Ian3s offers an opportunity to reduce
disposal costs while making a beneficial use of the sludge.
Little information is available regarding the practicality or
environmental consequences of sludge treatment of strip mined sites.
165
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Therefore, the Shawnee National Forest in Illinois, in conjunction
with the Metropolitan Sanitary District of Greater Chicago, estab-
lished a demonstration site in 1970 to evaluate sludge treatment on
strip mined land. The demonstration site, a 77 hectare stripped
area, is known as the Palzo Tract. Within the Palzo Tract, four
plots (500 square meters each) were set up to monitor water quality
runoff and to observe plant growth following sludge treatment.
Monitoring of the plots has continued since 1970. Land reshaping
of the entire 77 hectares is underway in 1972 in preparation
for sludge application to the entire tract. These efforts are in
cooperation with Forest Service Research and university personnel.
This paper presents the 1970-1972 water, vegetative, and soil
observations from the small plots and considers the sampling
design for the larger area and an adjacent stream which is affected
by runoff from the tract.
THE CHEMICAL PROCESSES SPOIL
Chemical oxidation of pyrite in shales of stripped areas
is somewhat complex and not completely understood. The general
reactions, however, are described by Hill (1971) as follows:
2FeS2 + 2H20 + 702 2FeS04 + 2H2S04 (1)
Oxidation of the pyrite (equation 1) produces ferrous sul-
fate and sulfuric acid. The reaction continues as follows:
4FeS04 + 202 + 2H2S04 2Fe2 (S04)3 + 2H20 (2)
Fe2 (S04)3 + 6H20 2Fe (OH)3 + 3H2 S04 (3)
Oxidation of the ferrous iron precedes slowly. However, the
resultant ferric iron is reduced by the pyrite to release more
acid and ferrous iron (equation 4) .
FeS2 + 14F3+ + 8H20 15Fe2+ + 2S042" + 16H1+ (4)
Singer and Stumm (1968) and others also present evidence that
microbes possibly play an important role in the oxidation process.
Smith and Shumate (1971) indicate the reaction rates are a function
of pH, temperature and oxygen concentration conditions at the pyrite
surface. Erosion of stripped areas also continually exposes fresh
pyrite for oxidation.
PLOT VEGETATIVE RESPONSE
The four 500 square meter plots on the demonstration tract were
designed to sample subsurface flow. Each plot was treated with
166
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sludge in November 1970 at treatment levels of 304, 178 and 78
dry metric tons of sludge per hectare. The fourth plot remained
as a control. The following spring, the plots were seeded with
K-31 tall fescue (Festuca arundijiacea) and weeping lovegrass (Era-
grostis curvula) at the rates of 22 and 8 kilograms per hectare,
respectively.Within 30 days germination had occurred on all but
the control plot. At the end of the first growing season, there
was a ninety percent vegetative cover on the most heavily treated
plot, whereas the plots with lower treatments were less than 50
percent covered. In the second growing season only the 304 ton
per hectare treatment continued to support as much vegetation as
in the first growing season.
PLOT RUNOFF RESPONSE
Water samples collected from subsurface drains in the plots
have been analyzed for chemical and bacterial contamination since
the study began. The average acidity levels and concentrations
of various metals observed in runoff from the plots appear in
Table 1. The heaviest treatment (304 metric tons per hectare)
reduced acidity as well as aluminum and iron concentrations in the
runoff by more than 60 percent and manganese concentrations by
more than 50 percent. Slight increases in chromium, cadmium and
zinc concentrations were observed, however, as shown in Table 1.
(All of these elements also naturally appear in acid runoff from
the tract.)
Within the period of observation, a cyclic trend in metal
concentrations has been noted. From November 1970 through
September 1971, a sharp decrease in metal concentrations was
observed in the runoff. During the dormant season of 1971-1972,
a slight rise in concentrations occurred. With the onset of the
growing season during the spring of 1972, metal concentrations
began decreasing again. This cyclical pattern of concentrations
is perhaps associated with the seasonal availability of water and
with plant uptake of metals. The dormant season in the area co-
incides with the period of higher rainfall and lower evapo-
transpiration rates. The initial decrease in metal concentrations
in the runoff was likely due to neutralization of the spoil's
acidity by the highly alkaline sludge. The sludge, which contains
about 40 percent organic matter, also has a high cation exchange
and buffering capacity which may complex many of the metal cations
in the acid spoil. Also, uptake by plants during the growing
season was indicated by analyses conducted on the weeping lovegrass.
The observed increase in lead, chromium, cadmium and zinc, particu-
larly noted in runoff from the 178 ton treatment, implies that the
lower treatment rates are incapable of providing sufficient
buffering to help tie up certain metals. These metals, whose
solubility is pH dependent, probably passed through the
167
-------
00
Table 1. Average Concentration of certain Parameters in Subsurface Runoff from the Sludge
Treated Plots before and after Treatment ("after" values based on 1970-1972
averages)
Treatment (metric tons/hectare)
-304-
Element
Al
Cd
Cr
Cu
Fe
Mn
Pb
so4
Zn
Acidity
Before
1,240
1.14
3.5
11.6
3,700
70
0.33
11,000
24.4
22,940
After
402
1.92
4.8
7.5
1,260
30
0.23
7,740
36.4
8,900
-178-
Before
- milligrams
395
0.31
1.3
3.8
1,280
51
0.16
8,400
8.1
7,310
After
per liter -
138
1.18
1.6
3.3
320
17
0.18
3,730
24.8
3,320
-78-
Before
440
0.70
2.3
4.0
1,000
71
0.42
7,100
14.1
7,040
After
346
1.13
3.4
3.6
822
42
0.18
6,770
26.0
5,900
-0-
Average
548
0.66
2.1
4.5
1,620
36
0.22
7,980
13.3
9,770
-------
inadequately neutralized spoil, to appear in the runoff. In sum-
mary, these initial results indicate that sludge treatment of acid
spoils apparently must be at a high enough level to neutralize the
spoil in order to prevent additional water pollution by metals and
to maintain a vegetative cover. The heaviest treatment of 304
metric tons per hectare appeared to be most desirable.
NUTRIENTS
Although the sludge contains about 5 percent dry weight of
nitrogen, only 1 to 2 percent are in the water soluble form of
ammonia and nitrate. Merz (1959) indicates that as much as 80
percent of the nitrogen in sludge may remain in the organic form
the first year. The slow availability of the nitrogen is highly
desirable for plant growth and water quality considerations.
Analysis for NOs-N and N02-N in runoff from the test plots has
shown no concentrations exceeding State water quality standards.
Concentrations of NHU-N ranged from 54.0 mg/1 10 months after
treatment on the most heavily treated plot. The high levels of
NH3-N and 0-N, in conjunction with no consistent increases of
N02-N and NOs-N, indicate that the acidity of the spoil material
and/or the heavy metal concentrations probably are preventing
nitrification. Once a high enough pH is established, nitrifi-
cation could be anticipated and NH^-N concentrations presumably
would decrease. Establishment of sorghum and millet, both high
nitrogen demanders, possibly would minimize nitrogen concentrations
in the runoff.
BACTERIA
No fecal coliform bacteria were found in runoff from the
sludge treated plots during the year immediately following
application. A digestion period of 7-10 days during municipal
treatment kills pathogenic organisms, according to Burd (1966).
Also, lagooning of a sludge for 30 days after digestion further
reduces fecal coliforms by 99 percent (Braids, 1970). The sludge
used by Palzo has been lagooned for over two years. Exposure
to ultraviolet radiation by spreading the sludge on the ground
is detrimental to bacteria. Finally, fecal coliforms in contact
with acid water with a pH of 2.5 for 24 hours exhibit a die-off
of greater than 99 percent (Joseph and Shay, 1952). Considering
all of these factors, it appears unlikely that pathogens would
survive in the runoff.
SPOIL OBSERVATIONS
The maximum level sludge treatment effectively raised the
pH of the acid spoil. As would be expected, the major difference
169
-------
in pH between the treatment and control plot spoil is in the top
20-25 centimeters. The average pH based on nine observations per
plot taken at various times during the first year following treat-
ment showed the following:
Plot Average
Treatment Rate Soil Surface pH
(dry metric tons/Hectare)
304 6.2
178 5.2
78 4.7
0 2.3
Laboratory analyses of percolate from the spoil were made to
supplement the field runoff and spoil pH observations. Columns of
spoil approximately one meter by five centimeters were augered from
the most heavily treated and the control plots in 1972. The spoil
cores then were transported in two layers to the laboratory (0-50
centimeter and 50-100 centimeter layers) and leached with distilled
water. About one-half year's equivalent of precipitation (1000 ml)
was percolated through the individual columns during a ten-day
period. The percolate was analyzed for the parameters shown in
Tables 2 and 3, plus calcium and magnesium.
These preliminary percolate analyses of July 1972 indicate
that mixing of the sludge into the spoil was apparently more
effective than simple surface application in terms of water quality
improvements. As shown in Tables 2 and 3, acidity was reduced in
percolate from the treated plot's spoil when sludge was mixed into
the spoil (note hydrogen ion concentration). Likewise, iron con-
centrations in the percolate were greatly reduced by the sludge
incorporation. Less impressive reductions appeared for sulfur,
manganese, aluminum, and copper.
Sludge application apparently increased zinc and sodiun levels
in the percolate water, as shown in Table 2. Hunt, et al. (1971)
noted that zinc apparently was weathered out of spoil wHen treated
effluent was applied by irrigation. Further observations are needed
to assess the significance of any metal releases that are associated
with sludge application.
If the zone of highest oxidation rates in the spoil can be
effectively neutralized and stabilized, the acid production should
be decreased. The zone of major oxidation in the spoil is recog-
nized by Good, et al. (1970) to be in the top 25 centimeters. This
zone has the clay removed by leaching and is most permeable to air
and water.
170
-------
Table 2. Concentrations of Chemical Constituents in the Percolate Collected from the 0-50 cm
Column of Spoil Material
Constituent
Treatment
304 t/ha
plot
Mixed
Unmixed
Control
Plot
Zn
mg/1
28.4
22.0
62.4
22.6
1.9
1.4
Pb
mg/1
3.5
4.5
20
4.5
5.0
5.0
Fe
mg/1
trace
trace
42
1.9
5400
11
S .
1
0.058
0.060
0.135
0.063
0.082
0.071
Mn
mg/1
2.0
1.0
2.8
13.0
3.3
2.2
Cu
mg/1
0.5
--
3.2
1.2
0.6
0.2
Na
mg/1
7.1
5.8
3.2
3.8
0.9
1.8
Al
mg/1
105
155
960
1300
210
1300
K
mg/1
28.0
16.0
0.2
0.5
0.1
—
H
meq/1
1.38
1.92
54.15
11.35
36.96
11.97
Co
mg/1
0.2
0.1
0.1
0.2
0.5
0.1
Ni
mg/1
3.5
2.8
4.2
2.8
1.0
0.5
-------
Table 3. Concentrations of Chemical Constituents in the Percolate Collected from the 50-100 cm
Column of Spoil Material
Constituent
Treatment
304 t/ha
plot
Mixed
Unmixed
Control
Plot
Zn
mg/1
37.4
4.8
48.4
29.6
40.4
1.2
Pb
mg/1
4.6
5.0
5.5
4.7
6.5
4.9
Fe
mg/1
trace
trace
196
14
2600
4600
S
%
0.077
0.045
0.098
0.055
0.229
0.069
Mn
mg/1
3.0
0.5
17.5
4.0
12.8
2.8
Cu
mg/1
0.4
--
2.2
1.0
1.2
0.6
Na
mg/1
9.9
4.3
2.7
4.5
8.7
0.8
Al
mg/1
370
250
2500
920
12600
1200
K
mg/1
78.0
22.0
0.2
0.4
0.1
0.2
H
meq/1
4.49
2.11
30.92
11.70
33.14
28.71
Co
mg/1
0.2
0.2
0.2
0.4
0.1
0.2
Ni
mg/1
4.5
1.0
3.8
2.5
7.7
0.5
-------
Infiltration capacities averaging 7,400 cm/hr have been
measured in the top 40 on of Palzo spoil. The second zone, imme-
diately below this highly permeable zone, has a lower permeability
due to clay fines precipitated by rain. However, the permeability
of the deeper zone is not strikingly lower in the samples studied
at this site. Below 40 cm, permeability averages 6,200 cm/hr. A
very wide range of permeability in these samples suggests more
samples are needed to increase the precision of the estimate. A
third zone suggested by Good, et_ al. (1970), is the deepest area
where little, if any, oxidation occurs.
LARGE SCALE OPERATIONS
Following the results of the plot work discussed above and
considering the results of researchers in the same subject area,
the Forest Service has decided to apply sludge on the larger tract
surrounding the test plot.
The entire 77 hectare acid producing watershed, where the
spoil pH ranges from 1.9 to 4.0, will be treated with anaerobically
digested sludge. The purpose of the demonstration is to test the
practicality of sludge treatment on a large scale.
The sludge will probably be obtained from the Metropolitan
Sanitary District of Greater Chicago. It will be shipped, by
rail, unloaded in a receiving lagoon, and piped to a storage
lagoon on the site, which will hold 1.020 x HP cubic meters of
sludge.
The 77 hectare area has been extensively leveled and reshaped
in June-July 1972. Digested sludge will be applied to the site at
a rate of 626 dry metric tons per hectare over a two or three year
period. Either an irrigation sprinkler system or gated irrigation
pipe will be used to apply the sludge. Before and during sludge
application, the site will be disked to increase infiltration.
Infiltration tests run on the most heavily treated test plot indi-
cate that upon saturation, infiltration capacities average only
about 25 cm/hr. Thus, successful irrigation must be intermittent
to allow soil drainage.
The planned rate of application is twice that of the most
heavily treated test plot. The 304 metric ton per hectare plot
had sludge mixed to a depth of about 8.0 cm. However, since the
upper 25 on is reported to be the zone of most extensive oxidation
by Good, et al. (1970), it seems desirable to mix the sludge to
this deptET I? possible. Complete disking on the entire tract will
mix the sludge to the first 15 to 20 cm. Although the amount of
sludge applied will be about twice that of the most heavily treated
plot, it will be mixed to about twice the depth. This sludge-spoil
173
-------
combination will contain about 20 percent sludge and should provide
a good rooting zone for plant establishment.
The nutrient value of the sludge is high enough to support
plant growth. Hinesly (1972) claims the N:P:K ratio to be 33:18:4.
The nutrient loading rate for the suggested application rate will
be: nitrogen-7,670 kilograms per hectare, phosphorus-4,180 kilo-
grams per hectare and potassium-930 kilograms per hectare. As
previously discussed, most of the nitrogen is in the organic form
and thus, will be available to the plants over a long period of
time. Supplemental potash may be required.
The immediate establishment of K-31 tall fescue (Festuca
arundinacea), weeping lovegrass (Eragrostis curvula), and orchard
grass (Dactylis glomerata) should provide erosion protection.
The planting of shortleaf pine (Pinus echinata), Virginia Pine
(Pinus virginiana), cottonwood (Populus deltoides) and black locust
(Robinia pseudoacacia) should provide further stabilization. If
vegetation can be well established and erosion controlled, acid
production from the site should basically be reduced by a combina-
tion of the following factors:
1. Neutralization of the surface acid producing spoil (and
chelation of the metals).
2. Erosion control to prevent exposure of fresh pyritic
material.
3. A decrease of surface and subsurface water flow from the
site, due to increased evapotranspiration losses.
THE RECEIVING STREAM
The acid water leaving the tract has a very low pH and high
acidity concentration. Calculations based on sampling observations
and average stream discharge data indicate that approximately 9,000
metric tons per year of acidity are contributed to the adjacent
receiving stream. This acid runoff is generally considered to be
one of the worst in the State of Illinois. Table 4 describes the
impact of the Palzo runoff upon the chemistry of the stream.
In addition to stream sampling above and below the Palzo Tract,
a water quality survey was made every 75 to 100 meters along the
1.5 kilometer section of the adjacent stream. The purpose of the
stream survey was: (1) to identify apparent acid input points;
(2) to describe patterns of stratification, mixing and assimilation
of the acid into the stream; and (3) to determine the range of
174
-------
water quality within individual cross sections of the stream.
These survey data serve both as pretreatment information and as a
basis for stream sampling design.
Table 4. Impact of Palzo Runoff on Sugar Creek as shown by
the 1969 to 1971 Stream Samples
Sugar Creek Palzo Sugar Creek
Pollutant Above Palzoi/ Runoff!/ Below PalzoV
Al
Fe
Mn
504
Acidity
mg/1
59
49
5.7
558
338
mg/1
2,075
3,955
320.0
23,675
20,100
mg/1
306
529
51.4
3,731
3,232
Specific
Conductance 825 14,885 3,329
(umhos/cm)
I/ Upper 40 cm layer of stream only.
2/ Surface flow emerging from the tract.
Water quality changes along the stream (Sugar Creek) are most
striking. For example, values of pH and conductivity change from
around 6.0 pH units and 500 micromhos per centimeter upstream, to
less than 3.0 pH units and over 11,000 micromhos per centimeter
downstream.
The stream cross sections above the stripped tract are fairly
uniform in water quality. However, once acid inputs occur, a
distinct and stable stratification appears.
Inputs of acid water into upstream reaches of the creek by
the Palzo Tract appear to be neutralized, presumably because of
dilution and buffering effects. However, once the stream's moder-
ate buffering capability is overwhelmed, stratification becomes
continuous.
The extreme water quality stratification in the receiving
stream emphasizes the need for integrated or layered sampling, if
one is to correctly evaluate water quality changes occurring in
the stream.
175
-------
MONITORING DESIGN
A monitoring system will be initiated on the site to determine
the large scale effect of treating the spoil banks with digested
sewage sludge. Water, spoil and plant responses will be observed
in a variety of ways.
Since the Palzo Tract is now causing severe pollution problems,
as shown in Table 4, monitoring the water leaving the area will be
most important. The following main sites will be monitored:
a. Two Palzo surface runoff stations on the tract, with
continuous pH, electrical conductance and flow measurements.
Weekly samples will be analyzed for chemicals and bacteria.
b. Two Sugar Creek stream stations, with continuous pH,
electrical conductance and flow measurements. Weekly samples will
be analyzed for chemicals and bacteria.
c. Twenty-two shallow groundwater stations, spaced about 65
meters apart along the saturated zone. Bi-weekly samples will be
taken after treatment begins and analyzed for selected parameters.
d. Twenty soil moisture stations randomly located at 20 to
100 cm depths throughout tract. Monthly observations will be made
for selected parameters.
The basic objectives of the above design are:
a. To determine if runoff from the tract is in compliance
with Federal and State water quality standards.
b. To establish a good baseline record of water quality
parameters before sludge treatment.
c. To determine the pattern and relationship of individual
elements entering Sugar Creek. This information should allow
composite sampling and analysis of index parameters, in order to
reduce the number of observations.
Monitoring in subwatersheds (within the tract) will be used
to determine effects of particular treatments on selected areas.
Important measurements in the subwatersheds will include observa-
tion of the hydrologic response of the area due to treatment,
monitoring of fecal coliform counts during and after sludge
application, and evaluation of chemical parameters in runoff
following selected levels of treatment.
176
-------
COOPERATIVE RESEARCH
In addition to the demonstration work, the North Central Forest
Experiment Station will utilize a randomized block design to study
the effects of various levels of sludge and limestone applications
upon soil chemistry, water quality and plant growth.
The Forestry Department of Southern Illinois University,
supported by the National Science Foundation, also is studying
plant and soil response of sludge and limestone treatments upon
acid spoil as it varies with depth of incorporation into the
spoil. They are investigating vegetative response of 12 grasses
and six tree species.
The Agronomy Department of the University of Illinois presently
is studying pyrite and other forms of sulfur in the acid spoil.
They will examine redox potential of the spoil at various depths to
describe the rate of change in surface and subsurface spoil materials
resulting from sludge treatments.
SUMMARY
This report details the preliminary results of a strip mined
reclamation demonstration project in Southern Illinois. The initial
observations indicate that treated municipal sludge, when applied
to the spoil in sufficient amounts, improves spoil pH, allows
establishment of vegetation and reduces acidity and concentrations
of some of the chemicals in the runoff issuing from the tract.
The proposed application of sludge to a larger 77 hectare
area should provide some insight into the practicality of sludge
treatment on strip mined areas. If such treatment is practical,
three main advantages could possibly result: (1) reclamation of
useless stripped areas, (2) reduction of water pollution associated
with these areas, and (3) the disposal of municipal sludge.
Anderson, D. A., S. H. Kunkle and D. R. Hedrich. 1972. Affluence,
effluence, and new roles for forest hydrology in the East.
Proc. Amer. Water Resources Assoc., Fort Collins, Colorado,
June 1972, 14 p.
Braids, 0. C., M. Sobhan-Ardakani and J. A. E. Molina. 1970.
Liquid digested sewage sludge gives field crop necessary
nutrients. Illinois Res. 12(3), 6-7.
Burd, R. S. 1966. A study of.sludge handling and disposal.
Publication WP-20-4. Federal Water Poll. Control Admin.
USDI. Cincinnati, Ohio.
177
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Dalton, Frank E., J. E. Stein and B. T. Lynam. 1968. Land reclama-
tion - A complete solution of the sludge and solids disposal
problem. Jour. Water Poll. Control, 40, 5, 789-800.
Good, D. M., U. T. Ricca and K. S. Shumate. 1970. The relation
of refuse pile hydrology to acid production. Third Symposium
on Coal Mine Drainage Research, 145-149.
Hill, Ronald D. 1971. Restoration of the terrestrial environment -
The ASB Bulletin, 16,3, 107-116.
Hinesly, Thomas D. 1972. Personal contact. Department of Agronomy,
University of Illinois.
Hunt, Clifford F., W. E. Sopper and L. T. Kardos. 1971. Renova-
tion of treated municipal sewage effluent and digested liquid
sludge through irrigation of bituminous coal strip mine
spoil. The Pennsylvania State University, Technical Paper,
Institute for Research on Land and Water Resource, 118 p.
Joseph, J. M. and D. E. Shay. 1952. Viability of Escherichia coli
in acid mine waters. Amer. Jour, of Pub. Health, 42, 795-800.
Merz, Robert C. 1959. Utilization of liquid sludge. Water and
Sewage Works, 106, 489-493.
Patterson, J. R. and J. Gschwind. 1971. Human and animal wastes
as fertilizers. Fertilizer Technology and Use, 577-594.
Singer, P. C. and W. Stumm. 1968. Kinetics of the oxidation of
ferrous iron. Second Symposium on Coal Mine Drainage Research.
Mellon Institute, 12-34.
Smith, E. E. and K. S. Shtmate. 1971. Rate of pyrite oxidation
and acid production rate in the field. Presented at Acid
Mine Drainage Workshop. Athens, Ohio, 11 p.
Sopper, W. E. 1970. Revegetation of strip mine spoil banks
through irrigation with municipal sewage effluent and sludge.
Compost Sciences, 6-11.
Udall, Stewart L. 1967. Surface mining and our environment. U.S.
Department of the Interior, 124 p.
178
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EFFECTS OF LAND DISPOSAL OF WASTEWATERS
ON SOIL PHOSPHORUS RELATIONS
J. E. Hook, L. T. Kardos and W. E. Sopper
Department of Agronomy and School of Forest Resources
The Pennsylvania State University
At present there is an increasing useage of soil and soil-plant
systems as a final treatment and disposal system for municipal and
industrial wastewaters. The success of a land disposal site depends
upon the ability of the soil to temporarily fix and store effluent
constituents for use by plants and microbes and to prevent the
migration of contaminants to the groundwater (Kardos, 1970). The
movement and the fixation of phosphorus, a major constituent of many
wastewaters, are important considerations in these disposal systems.
In the Wastewater Renovation and Conservation Research Project at
The Pennsylvania State University, the fate of phosphorus has been
monitored as treated municipal sewage effluent was applied to crop-
land and forested areas. Ten years of monitoring has indicated a
high degree of efficiency of the soil-plant system to retain and
use phosphorus. The purpose of this report is to describe the
chemical forms in which the phosphorus was being retained and to
what depth in the soil it was accumulating.
METHOD OF STUDY
To evaluate phosphorus, as well as other constituents, of the
treated wastewater, an extensive monitoring network was established.
Its purpose was to collect water samples in the soil and underlying
substratum. This network is described in detail elsewhere (Parizek
elt al, 1967). Yields of harvested crops were measured and samples
were analyzed for phosphorus content by the method reported by
Baker et al (1964).
Soil samples from the various treatment and control areas were
analyzed for pH, organic matter, free iron, free aluminum, and
available phosphorus. Organic matter and pH were determined by the
methods of Peech et al^ (1947). Available phosphorus was determined
using the dilute hydrochloric acid, dilute NfyF extractant of Bray-
as described by Jackson (1956). Phosphorus in the soil samples was
fractionated according to the scheme of Chang and Jackson (1957)
with modifications of Glenn et al (1959) and Peterson and Corey
(1965). Free iron was determined" in the citrate-dithionite extract
of the phosphorus fractionation scheme. Basically it was the
extractant described by Aguilera and Jackson (1953). Free aluminum
179
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was the aluminum extracted by the NH4F (pH 8.2) extract of the
phosphorus fractionation scheme.
The areas which received effluent included two major soil
series. The Morrison sandy loam and the Hublersburg clay loam.
These series have quite different properties and represent two
possible extremes of the range of deep well drained Pennsylvania
soils. Several properties of these soils which affect movement
and fixation of soluble phosphorus are presented in Table 1.
Treatments of these areas included variations of effluent
levels, usually zero, one and two inches per week and variations of
vegetative cover. Although as many as 42 plots have been studied,
only four treatment and three control plots will be considered in
this paper. Each of the treated areas considered here was irrigated
with two inches of effluent per week.
The agronomy area, located on Hublersburg clay loam was divided
into seven crop rotation strips. The crop sequence is presented in
Table 2.
Treatment was two inches of effluent per week and a control
which received fertilizer phosphorus. The amount of effluent
applied, concentration of phosphorus in the effluent and the amount
of phosphorus applied for the eight years of treatment are presented
in Table 3. From the phosphorus content and yield data, the
average removal of phosphorus on the treated site was calculated
and is also presented in Table 3.
The net amount remaining - the total applied, 620.7, minus the
removal by crops, 206.3, or about 414 pounds per acre per year - is
a measure of the amount which is being held by the soil.
The reed canarygrass area, located on Hublersburg clay loam,
was irrigated with effluent year round. The grass was established
in 1964, and since 1965 three cuttings were made each year except
in 1968 when only two cuttings were made. The amount of phosphorus
removed yearly by the grass is shown in Table 4. Also presented in
that Table are the amount of effluent applied, concentration of
phosphorus in the effluent and amount of phosphorus applied.
The old field area, located on Hublersburg clay loam, was
usually irrigated from May through November each year. This field,
abandoned in the early 1930's, has received no commercial fertilizer.
Growth responses of the vegetation have been measured (Sopper, 1971)
but none of the vegetation has been removed. The area is covered
with a variety of weeds and has a scattered stand of white spruce
(Picea glaucus M.). The old field control plot is similar but has
received no effluent.
180
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TABLE 1. Some Properties of the Two Soils at the Areas Which Were
Used in the Effluent Irrigation Project
Area
Soil
Depth
inches
pH
Organic
Matter
%
Hublersburg clay
Agronomy Control
Reed Canarygrass
Irrigated
Old Field Control
0-12
12-24
24-36
36-48
48-60
0-12
12-24
24-36
36-48
48-60
0-12
12-24
24-36
36-48
48-60
5.6
5.1
5.1
5.0
4.9
6.4
5.8
5.4
5.3
5.1
5.2
5.2
5.1
5.1
5.1
2.96
0.86
0.40
0.20
0.15
3.01
0.82
0.34
0.18
0.09
2.39
0.54
0.23
0.21
0.21
Morrison sandy
Gamelands Forest
Control
Gamelands Forest
Irrigated
0-12
12-24
24-36
36-48
48-60
0-12
12-24
24-36
36-48
48-60
4.8
4.9
5.0
5.0
4.9
5.5
5.2
5.0
4.7
4.7
1.67
0.31
0.25
0.19
0.19
1.43
0.30
0.14
0.12
0.12
Free
Iron
% Fe203
loam
3.44
4.54
5.70
6.15
6.75
3.62
5.00
5.25
5.35
5.42
3.94
5.30
5.80
5.80
5.80
loam
1.66
2.14
2.31
2.22
2.71
1.21
2.08
2.17
2.32
2.37
Clay
Content
%
--
--
--
--
--
43
52
49
45
41
_-
--
—
--
--
15
28
28
16
36
--
--
--
--
--
181
-------
TABLE 2. Yearly Crop Sequence for the Seven Strips in the Agronomy Area
Strip
Number
1
2
3
4
5
6
7
1963
corn
wheat
red clover
wheat
corn
red clover
alfalfa
1964
oats
red clover
corn
red clover
oats
corn
corn
1965
alfalfa
corn
oats
corn
alfalfa
oats
oats
Year
1966
alfalfa
corn
alfalfa
corn
alfalfa
alfalfa
alfalfa
1967
alfalfa
corn
alfalfa
corn
alfalfa
alfalfa
alfalfa
1968
corn
corn
corn
corn
corn
corn
corn
1969
corn
corn
corn
corn
corn
corn
corn
1970
corn
com
corn
com
corn
corn
corn
1971
com
corn
corn
corn
com
corn
corn
GO
-------
TABLE 3. Concentration of Phosphorus in the Effluent and Amounts of Phosphorus Added by Effluent
Irrigation and Removed by Crop Harvest in the Agronomy Area Receiving Two Inches of
Effluent at Weekly Intervals
1963
1964 1965 1966
Year
1967
Average concentration of P
9.70
1968 1969
in effluent (mg/1)
8.55 6.95 5.35 6.75 7.10 6.55
Amount of Effluent Applied (inches/year)
1970 Total
4.15
48 66 58 64 52 40 32 32 392
L «
oo Total Phosphorus Applied (Ibs/acre/year)
105.
26.
7
3
127.
18.
8 91.1
Average Amount
5
27.1
77.9
of Phosphorus
31.8
76.2
removed
24.8
64.4
by all crops
~
47.6 30
(Ibs/acre/year)
43.1
34.7
620.
206.
7
3
I/ No harvest
-------
TABLE 4. Concentration of Phosphorus in the Effluent and Mounts of Phosphorus Added by Effluent
Irrigation and Removed by Crop Harvest in the Reed Canarygrass Area
1964
Year
1965 1966 1967 1968 1969
1970
Total
Average concentration of P in the effluent (mg/1)
8.55
66
127.8
!/
6.95 7.70 7.70 8.45 4.20
Amount of effluent applied (inches/year)
80 78 94 98 100
Total phosphorus applied (Ibs/acre/year)
125.7 135.9 163.9 187.6 94.8
Average amount of phosphorus removed by reed canarygrass
40.0 33.4 55.9 47.2 47.2
4.05
86
_ _
602
88.8 924.5
(Ibs/acre/year)
56.0
279.7
— No harvest
-------
The gamelands area, located on Morrison sandy loam soil, has a
mixed hardwood forest vegetation. The plot (New Gamelands) for which
lysimeter data is presented has been irrigated on a year round basis
since 1965. The control, adjacent to this plot has not been irri-
gated or fertilized. For analysis of total soil phosphorus (the
fractionation data) a nearby plot (Old Gamelands) which has been
irrigated since 1963 was used. This plot has received various levels
of effluent irrigation since 1964 and prior to sampling in 1970 had
received a total of 600 inches of effluent.
RESULTS
One of the first questions to be considered was that of how much
phosphorus was leached through the soil. The concentration of phos-
phorus in the percolating soil water was derived from the suction
lysimeter data. These lysimeters sampled water in and just below the
plant root zone. The mean annual concentrations of phosphorus in
the soil water of the treated and control areas is presented in
Table 5.
In the agronomy area, mean annual concentration in samples from
the control site at a depth of 48 inches varied within a range of
0.030 to 0.080 ppm. These concentrations represent the normal back-
ground phosphorus which is in equilibrium with the soil phosphorus.
These concentrations are considered typical for this heavy textured
soil. The mean annual concentration in samples from the old field
control area also fell within this range.
When treated with effluent from 1963 to 1971 the percolate in
the agronomy area has shown no increase in phosphorus concentration
at the 48 inch depth. Only a slight inconsistent increase occurred
at 24 inches. At 6 inches the percolate concentration in the treated
area varied considerably but was consistently higher than in the
control area. Since the effluent concentration was about 7 ppm and
the highest percolate concentration was about 0.6 ppm a reduction of
greater than 901 occured after water percolated through only 6 inches
of soil.
The reed canarygrass area was as effective as the agronomy area
in reducing phosphorus concentrations in the soil percolate. The
concentration at the 24 inch depth in the reed canarygrass area was
only slightly higher than in either the agronomy control or the
treated area, and has remained nearly constant. The increase which
occurred in 1971 at the 6 inch depth was a result of a substantial
increase in both concentration and amount of applied phosphorus.
During most of that year effluent containing stabilized digester
sludge (approximately one part of sludge slurry to eleven parts of
effluent) was applied to that area. This effluent-sludge mixture
185
-------
TABLE 5. Mean Annual Concentration of Phosphorus (mg/1) in Soil Percolate Samples Taken at Three
Depths from Both Effluent Treated and Control Areas
oo
ON
Area
Agronomy
Agronomy
Reed Canarygrass
Old Field
Old Field
New Gamelands
New Gamelands
Effluent
Amount
in./wk
0
2
2
0
2
0
2
Soil
clay loam
clay loam
clay loam
clay loam
clay loam
sandy loam
sandy loam
1965
6 -Inch
.035
.145
--
--
--
--
—
24 -Inch
Agronomy
Agronomy
Reed Canarygrass
Old Field
Old Field
New Gamelands
New Gamelands
0
2
2
0
2
0
2
clay loam
clay loam
clay loam
clay loam
clay loam
sandy loam
sandy loam
.055
.040
.025*
--
--
--
--
48- Inch
Agronomy
Agronomy
Reed Canarygrass
Old Field
Old Field
New Gamelands
New Gamelands
0
2
2
0
2
0
2
clay loam
clay loam
clay loam
clay loam
clay loam
sandy loam
sandy loam
.030
.025
.010*
--
--
—
"• ~"
1966
Depth
.050
.250
.165
.040*
.090
.050*
.265
Depth
.045
.060
.085
.030*
.070
.090*
.030
Depth
.040
.040
.055
.030
.060
.060*
.040
1967
.045
.600
.140
.045*
.140
.050*
.115
.045
.090
.100
.032
.095
.225*
.050
.040
.070
.055
.040
.070
.070
.055
Year
1968
.060
.620
.190
.000*
.260
--
.450
.045
.080
.105
.120*
.125*
.035*
.130
.040
.075
.060
.040
.055
.075*
.115
1969
.025
.500
.205
.035
.295
.045
.320
.070
.060
.100
.220*
.120*
.030*
.105
.080
.095
.030
.050
.100
.105*
.140
1970
.035
.135
.135
.035
.340*
.050
.630
.060
.090
.075
.100*
.120*
.025*
.130
.045
.080
.045
.040
.115*
.050*
.155
1971
.045
.120
.210
.030*
.995
.090*
.965
.040
.065
.105
.025*
.250*
.040*
.090
.035
.060
.060
.040*
.420*
.025
.265
* Indicates means computed from fewer than 10 samples.
-------
had a total phosphorus level of 20 to 25 mg/1 and an orthophosphate
level of 15 to 15 mg/1.
In the old field treated area, though located on the Hublersburg
clay loam soil, the percolate has increased in phosphorus concentra-
tion more than in the treated agronomy and reed canarygrass areas.
This greater increase occurred to the 48 inch depth. The factor which
may have contributed most to this increase was that phosphorus was
not removed in a harvested crop. The phosphorus cycled through the
soil rather than being removed. The old field was also treated with
effluent each year for as many as ten weeks longer than the agronomy
area.
At the gamelands treated area, located on the Morrison sandy
loam soil, effluent irrigation has resulted in a substantially
greater increase in phosphorus concentration in the soil percolate.
While treated sites on the Hublersburg soil have concentrations about
the same as the agronomy control, the gamelands treated area has shown
a steady increase above that of the control area since the irrigation
began in 1965. One reason for this greater increase is the recycling
of phosphorus through the forest litter. A more important reason is
the lower clay content and lower content of sesquioxides in the soil
(Table 1). The effect of these properties will be discussed in
greater detail later.
If a few assumptions are made concerning the movement of water,
these concentrations of phosphorus in the soil water can be used to
calculate the amount of phosphorus which may be leaching into the
substratum. In 1970, for example, 86 inches of effluent were applied
to the reed canarygrass area. The total rainfall that year was 47
inches. Of that, approximately 26 inches!/ were lost by evapotrans-
piration. Assuming that the total of effluent and recharge - 107
inches - percolates downward (no interflow or runoff) at the mean
concentration of phosphorus found in the six-inch lysimeter - 0.135
mg/1 - then a total of 3.3 Ibs/acre/year would move downward. By
the time this reaches four feet the concentration is reduced to
0.060 mg/1. From this depth only 1.4 Ibs/acre/year would leave the
irrigated area. This is only 1.7* of the 89 Ibs/acre added that
year.
= This value represents the potential evapotranspiration as calcu-
lated by the Thornthwaite equation. Taylor, S. A. and Ashcroft,
G. L. 1972. Physical Edaphology. W. H. Freeman and Co; San
Francisco, pp. 64-66.
187
-------
Very little of the phosphorus added with effluent has been
lost by leaching. The remainder, 98.3%, has been removed by crops,
has been held by the soil and has been lost in runoff. The amount
of runoff is not exactly known for each treated area, but it has
not been excessive. The agronomy and old field areas were irrigated
during the driest part of the year. Runoff occurred only during
heavy rainstorms. The reed canarygrass area had a considerable
amount of runoff during winter and spring. The amount of water
lost as runoff from a sub-watershed of this area occassionally
exceeded the amount applied as effluent (Myers, 1967). Ice covered
ground, saturated soils, negligible evaporation and increased pre-
cipitation led to higher runoff during winter irrigation. Myers
showed that the runoff which passed the weir below this sub-watershed
of the reed canarygrass area had a lower phosphorus concentration
then the applied effluent even when no precipitation was available
to dilute the runoff. This was interpreted as indicating that a
portion of the effluent had entered the soil, moved downslope as
interflow and seeped back to the surface with a lowered phosphorus
content.
Runoff losses of phosphorus from the irrigated areas on the
sandy Morrison soil were probably very low. Even during winter a
thick leaf mulch and sandy surface soil prevented runoff. Inter-
flow on top of clay layers in the soil contributed most downslope
movement of irrigated water. Rebuck (1967) intercepted runoff and
shallow interflow from an effluent irrigated area located on this
soil. He found an average 8% loss of irrigation water when appli-
cation rates were between one and three inches per week. Since
much of this water was from interflow, the effluent had contact
with the soil for enough time to substantially lower the phosphorus
concentrat ion.
The amount of phosphorus removed by crops is a large and
important part of the effluent treated sites. The data in Table 3
indicates that the crops removed from 14 to 115 percent of the
phosphorus added annually to the agronomy area. The net phosphorus
added since the beginning of effluent treatment increased until 1968
after which it has actually decreased. This was due to the decrease
in added phosphorus and increase of phosphorus removed by the crop.
Ideally, if the amount added would just equal the amount removed
in harvest, phosphorus would not build up in the soil and the con-
centration of phosphorus in the percolate would be expected to
remain constant or decrease.
In the reed canarygrass area (Table 4), higher phosphorus
applications have resulted in a continued net increase in phos-
phorus not removed by the crop since irrigation began. Though the
reed canarygrass removes slightly more phosphorus than the agronomic
188
-------
crops (Table 2), it has removed only 30 to 60 percent of the total
added. At this site it is expected that the gradual increase in net
phosphorus, which represents primarily the amount which is building
up in the soil, will result in a gradual increase in phosphorus in
the percolating water.
In the old field and gamelands forest areas no harvest was made.
Some of the added phosphorus is taken up by the plants and trees in
these areas. Sopper (1971) reported higher concentrations of phos-
phorus in foliar material of irrigated hardwoods in the gamelands
than in the control. Similarly ground vegetation in the irrigated
old field area had a higher phosphorus content than in the control.
The forest vegetation in these treated areas did take up phosphorus,
but the extent to which this uptake contributes to renovation of the
effluent is not certain. Most of the phosphorus taken up by the
trees and ground vegetation is recycled in the litter. This must
obviously result in buildup of phosphorus in the soil and an eventual
• increase of phosphorus in the percolating water. This was found to
occur in both the old field and game land areas as discussed earlier.
When phosphorus is added to soils it usually is in the form of
orthophosphate anions. Even organic phosphates are mineralized to
this soluble form before being taken up by plants or reacting with
the soil. These anions bond chemically with surfaces of iron and
aluminum oxyhydroxides and will form precipitates with iron and
aluminum when these are in solution. The bonds formed from surface
and precipitation reactions vary in strength. The most weakly bonded,
that is the most soluble phosphates, readily equilibrate with the
soil solution and, hence, would be considered available to plants.
A good measure of the amount of this available phosphorus is the
Bray dilute acid-dilute fluoride extraction. This test was carried
out periodically with soils from the treatment plots.
Soil from the agronomy area showed an increase in Bray extract-
able phosphorus over the 9 years of treatment, although this increase
occurred only in the upper one foot of soil. The control plot which
received about 40 Ibs P/acre/year as commercial fertilizer, showed
a smaller increase. Below the top foot of soil no increase was
observed. In the reed canarygrass area soils were analyzed only two
years - 1969 and 1971. The amount of Bray extractable phosphorus
in the upper foot was 29.8 and 42.3 yg P/gram of soil for the two
years, respectively. Again there was no increase below the upper
foot of soil.
Bray phosphorus in the old field area increased approximately
the same as in the agronomy area. The control plot of this area,
which received no fertilizer, remained almost constant. In the
second foot of both control and effluent treated plots, the Bray
189
-------
phosphorus remained constant at less than 3.0 yg P/gram of soil.
These plots are all located on the Hublersburg clay loam. Effluent
additions have not increased Bray extractable phosphorus signifi-
cantly below the upper foot of this soil. As was pointed out earlier,
the effluent has caused increases in water soluble phosphorus of
percolate samples below the upper foot. This apparent discrepancy
is due to the fact that the concentration in the percolate is measur-
ing the equilibrium phosphorus in transit whereas the Bray extract
measures both equilibrium and reserve phosphorus with the latter
dominating in relative quantity.
In the old gamelands area on the Morrison sandy loam, however,
there was evidence that an increase of Bray phosphorus has occurred
to a depth of three feet. Samples were analyzed only in 1967 and
1971. In 1967, just 2% years after effluent irrigation began, Bray
phosphorus had reached 75.6, 4.9 and 2.2 yg P/gram of soil for the
1st, 2nd, and 3rd feet, respectively. This compared to 16.5, 2.1
and 1.2 yg P/gram of soil for the respective depths of the control
plot. In 1971 the irrigated area had 143.8, 31.6 and 9.9 yg P/gram
of soil and the control had 6.3, 1.5 and 0.7 yg P/gram of soil in
the respective depths. The Morrison sandy loam soil on which this
treatment area was located has shown a very large increase in Bray
extractable phosphorus in response to year round effluent irrigation.
A difficulty with the Bray extractable phosphorus test is that
this test does not measure all of the native or retained phosphorus.
It does indicate changes in the amount of phosphorus which is avail-
able to plants, and this amount is affected by treatments. However,
for many soils the Bray test measures less than 5% of the total soil
phosphorus.
To evaluate changes in the phosphorus content more completely
a fractionation of the soil phosphorus was carried out on soils from
some of these treatment plots. The procedure was used to explain
what has happened to the applied phosphorus and to relate this to
other measured properties of the soils.
The fractionation procedure separates the soil phosphorus into
four fractions: the MfyF - soluble fraction, the NaOH - soluble
fraction, the reductant soluble fraction and the F^SC^ soluble
fraction. While these phosphorus fractions do not represent dis-
crete chemical compounds, they do result from groups of related
compounds. The MfyF (pH 8.2) extracts phosphorus which is bound to
aluminum and aluminum compounds. NaOH extracts phosphorus bound to
the surfaces of iron compounds. The reductant solution dissolves
phosphorus compounds enmeshed within iron oxyhydroxides, and the
sulfuric acid extracts calcium -and magnesium phosphates.
190
-------
The phosphorus fractions were determined for the old field
control plot. The fractions are expressed as percent of the total
extracted. This total varied from 300 to 600 yg P/g soil. The
NaOH plus the reductant fractions made up 80 to 90 percent of the
total extracted soil phosphorus. These are the fractions asso-
ciated with iron. This was not surprising since total iron oxides
expressed as T?e2®3 ma<^e up 2 to 6 percent of those soils; whereas,
aluminum oxyhydroxides made up less than one half of one percent.
Calcium and magnesium in these soils exist primarily as exchangeable
cations. Chly a small portion, less than 61 of the total extracted
soil phosphorus was associated with calcium and magnesium. It is,
in fact, possible that this small percentage was actually related to
aluminum which was released after the iron reduction treatment.
NH^F - phosphorus made up less than five percent of the total
extracted phosphorus for most untreated soils, particularly sub-
soils. In the upper foot of the reed canarygrass effluent treated
plot it constituted 13 percent. In the upper foot of the agronomy
area control plot it was 16 percent. In the gamelands treated plot
NlhF phosphorus made up 43, 27, 17 and 11 percent of the total
fractions of the first through fourth feet, respectively. This
fraction, though not the most abundant, was probably the most im-
portant. This was demonstrated first by its relation to Bray
extractable phosphorus. It was found to be highly correlated with
this Bray test for plant available phosphorus. Its importance was
further demonstrated by its relation to effluent and fertilizer
treatments.
On the old field and agronomy control areas and the reed
danarygrass irrigated area located on the Hublersburg clay loam,
the greatest amounts of NttyF - phosphorus occurred in the upper
foot decreased sharply in the second foot and then remained rela-
tively constant in the deeper layers. Statistically significant
differences between the three areas were only present in the upper
foot. The reed canarygrass area which had been treated with
effluent had the greatest amount of NfyF phosphorus in the upper
foot and was followed in order by the agronomy area control plot
which has been receiving commercial fertilizer, and by the old
field control plot which has received neither effluent nor
commercial fertilizer.
In the forested plots located on Morrison sandy loam effluent
additions have significantly increased the amount of NJtyF phos-
phorus extracted when compared to the control. This increase
occurred in the second and third as well as the first foot. This
movement of applied phosphorus was similarly indicated by the Bray
test.
191
-------
There are several reasons why phosphorus has penetrated deeper
in this hardwood area of the Morrison soil. First, there is no
removal of harvested crops. As mentioned earlier phosphorus taken
up by growing plants is later released as the leaf litter mineral-
izes. Secondly, the sandy soil of this area has a greater hydraulic
conductivity; as a consequence the phosphorus in soil solution has
less time to react with particle surfaces. Third, the mineral
composition of the Morrison soil (Table 1) shows about one half as
much free iron as the Hublersburg soil. Further it has less alumi-
num oxyhydroxides and has less clay which would result in less
reactivity with phosphorus.
In addition to the noted effect of effluent treatments on the
NfyF fraction of the soils there was one other significant treat-
ment effect. This was with respect to the NaOH fraction of the
reed canarygrass plot. The effluent additions of phosphorus have
resulted in a slight increase of NaOH phosphorus, though only in
the upper foot. This should be expected. The fractions as separated
are in equilibrium with each other. Aluminum phosphate compounds
generally have a higher solubility than iron phosphates. As the
aluminum phosphates try to maintain their solubility, phosphate in
solution reacts with iron surfaces and iron in solution as these
become available for phosphate reactions. The long range effect
is to form the less soluble iron phosphates at the expense of the
aluminum phosphates.
By calculating the amounts of phosphorus added to the reed
canarygrass plot and by estimating the amounts lost by leaching,
runoff and crop harvest, a mass balance indicated that 500 pounds
of phosphorus per acre were retained by the plot in 6 years. This
amount was equal to the amount of phosphorus extracted in the NfyF
and NaOH fractions of the reed canarygrass topsoil minus the amount
extracted in these fractions from the untreated old field topsoil.
This mass balance indicates that most of the added effluent phos-
phorus can be accounted for in the MfyF and NaOH fractions.
CONCLUSIONS
Soils and soil plant systems may be effectively used to renovate
wastewaters. Applications must be managed so that the constituents
of the wastewater remain at the disposal site or leave in harmless
or beneficial forms. The water which leaves the disposal site should
have concentrations below USPHS recommended limits for drinking water
and below stream standards where applicable. In the case of phos-
phorus, a major constituent of municipal wastewaters, the soil-plant
system proves to be an excellent renovating media. When the system
is properly managed most of the added phosphorus remains in the soil
192
-------
at the disposal site or leaves as a nutrient in harvested crops.
Soils differ in their ability to hold phosphorus. In a heavy
textured soil high in sesquioxides, phosphorus from effluent irri-
gation did not increase in the soil below a depth of one foot after
7 years of irrigation. In a light textured soil with half as much
sesquioxides phosphorus content of soils increased to a depth of 3
feet after 6 years of treatment. The Bray test for available
phosphorus was suitable for determining zones of accumulation of
added phosphorus. The fractionation of total soil phosphorus
enabled a rough mass balance to be made for the phosphorus within
the disposal system.
ACKNOWLEDGEMENT
Research reported here is part of the program of the Waste
Water Renovation and Conservation Project of the Institute for
Research on Land and Water Resources, and Hatch Projects No. 1481
and 1809 of the Agricultural Experiment Station, The Pennsylvania
State University, University Park, Pennsylvania.
Portions of this research were supported by funds from
Demonstration Project Grant WPD 95-01 received initially from the
Division of Water Supply and Pollution Control of the United States
Department of Health, Education, and Welfare and subsequently from
the Federal Water Pollution Control Administration, United States
Department of the Interior. Partial support was also provided by
the Office of Water Resources Research, United States Department of
the Interior, as authorized under the Water Resources Research Act
of 1964, Public Law 88-379.
REFERENCES
Aguilera, N.H. and M.L. Jackson. 1953. Iron oxide removal from
soils and clays. Soil Sci. Soc. Amer. Proc. 17:359-364.
Baker, D.E., G.W. Gorsline, C.B. Smith, W.I. Thomas, W.E. Grube,
and J.L. Ragland. 1964. Technique for rapid analysis of corn
leaves for eleven elements. Agron. Jour. 56:133-136.
Chang, S.C. and M.L. Jackson. 1957. Fractionation of Soil
Phosphorus. Soil Sci. 84:133-144.
Glenn, R.C., P.H. Hsu, M.L. Jackson, and R.B. Corey. 1959. Flow
sheet for soil phosphate fractionation. Agronomy Abstracts,
p.9.
Jackson, M.L. 1956. Soil Chemical Analysis. Prentice-Hall.
Englewood Cliffs, New Jersey, 498 p.
Myers, J.C. 1967. A study of drainage conditions on a hillside
receiving sewage effluent at weekly intervals. M. S. Thesis.
The Pennsylvania State University, University Park, Pennsylvania
193
-------
Parizek, R.R., L.T. Kardos, W.E. Sopper, E.A. Myers, D.F. Davis,
M.A. Farrell, and J.B. Nesbitt. 1967. Waste Water Renovation
and Conservation. Penn State Studies No. 23, The Pennsylvania
State University, 71pp.
Peech, M., L.T. Alexander, L.A. Dean, and J. F. Reed. 1947. Method
of Soil Analysis for soil fertility investigations, United
States Dept. of Agric. Circular No. 757. Wash., D.C.
Peterson, G.W. and R.B. Corey. 1965. Modified Chang and Jackson
Procedure for Routine Fractionation of Inorganic Phosphorus.
Soil Sci. Soc. Amer. Proc. 30:563.
Rebuck, E.G. 1967. The Hydrologic Regime Due to Sprinkler Irrigation
of Treated Municipal Effluent on Sloping Land. M.S. Thesis. The
Pennsylvania State University, University Park, Pennsylvania
Sopper, W.E. 1971. Disposal of Municipal Waste Water Through Forest
Irrigation. Environ. Pollution 1:263-284.
Hortenstine:
Hook:
DISCUSSION
You described your method on soil phosphorus, that is
your chemical method, but nothing on the method of
determining soil solution phosphorus. What method did
you use on this?
The technique we used is one of the standard methods,
the ammonium molybdate-sulfric acid procedure.
Are there levels of phosphorus that can build up in
the soil that will be toxic to plants?
We certainly haven't come anywhere near levels that
would be toxic to plants and I don't know even what
level would be that high. There might be others here
that have an idea of what would be toxic levels...Dr.
Kardos says there's probably never any toxicity with
phosphorus. The phosphorus is just not available
enough in the soils although you may have a lot of it
there. For example, I mentioned, or might have men-
tioned, there were about 600 micrograms of phosphorus
per gram of soil extracted in the total fractionation
procedure. Of this only a very small fraction was
actually in solution at any one time.
How can one estimate the phosphorus requirement for
the bacteria so that you would be able to achieve
optimum degradation?
Again, I don't know that I'm really qualified to answer
that. The concentration is maintained in the soils,
that is background concentration has always been
sufficient for any bacteria. What minimal levels you
could get, I don't know. I've never seen concentration
194
-------
Goydan:
Kardos:
Unknown:
Ellis:
lower than about 0.005 ppms, and I don't know that
even that would be below the level microbes would need.
The phosphorus is there in very low concentration and
it's a matter normally, at least for higher organisms,
of how fast it can come into solution and get to the
plants and similarly it would be how fast it would get
to the microbes. I doubt that it would ever be
limiting.
In some industrial effluents where you don't have
phosphorus inherent in the waste, sludge or effluent,
and in other cases where you may not even have the
necessary nitrogen requirements, would you need a
means to predict the fertilizer requirements, say if
you're preparing the field?
I'll have to go along with what Mr. Hook said. I
don't think there's ever going to be a situation
with waste water renovation where phosphorus will be
limiting. The actual amount which the soil micro
population will need will be absolutely supplied
by anything that the effluent will have. Does that
answer the question?
If the effluent doesn't have phosphorus. In that
case, I would still say that the natural soil process
which is there should be quite sufficient to supply
the needs. I can only remember one case that I
noticed where there was a response to phosphorus, a
microbial response to phosphorus in soils, and that
was a sandy soil. Again, I think the soil phosphorus
would be quite available and adequate.
In response to the question before the last one, I've
never seen a case where we've had what I consider
phosphorus toxicity but the literature is full of
examples of phosphate-induced deficiencies. For
example, I've seen field beans that at zero phosphate
levels yield 30 to 34 bushels per acre and at 800
Ibs. of phosphorus per acre, they'll yield 6. It
turns out to be a zinc deficiency. So we might have
to really be careful of our management if we get into
areas of high phosphate applications.
195
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EFFECT OF LAND DISPOSAL OF WASTEWATER ON EXCHANGEABLE CATIONS
AND OTHER CHEMICAL ELEMENTS IN THE SOIL
Louis T. Kardos and William E. Sopper
Department of Agronomy and School of Forest Resources
«
The chemical changes that occur in soil through which the
applied wastewater percolates have usually been given less attention
than the changes occurring in the wastewater itself. This is under-
standable since most investigations of land disposal of wastewater
have been directed by sanitary engineers rather than soil scientists.
In a review of the literature by Edwards (1968) it was indicated
that most of the concern with respect to soil chemical changes was
with respect to changes in the amounts of sodium relative to the
other exchangeable cations in the soil. This concern with exchange-
able sodium stems from the well documented research in irrigation
agriculture which has shown that when the exchangeable sodium per-
centage reaches a value of about 15 a deterioration of soil structure
and adverse effects on infiltration can be expected in medium and
fine textured soils.
Henry et al (1954) in a 3 year experiment using sewage effluent
containing MD ppm of Na increased the exchangeable Na level to 2.37
m.e./lOOg and significantly decreased the exchangeable Ca and Mg,
but exchangeable K was unaffected. In spite of the high exchangeable
Na content there was no mention of any difficulty with infiltration.
In an investigation of primary sewage effluent spreading on five
California soils with relatively low clay content (3-10%), Sanitary
Engineering Research Laboratory (1955), it was reported that exchange-
able calcium and magnesium decreased while exchangeable sodium,
potassium and ammonium increased. Permeability of the soil was not
affected, probably because of the low clay content.
Edwards (1968) in soil samples taken in 1966 after 236 inches
of wastewater had been applied to the corn rotation area of the Penn
State Wastewater Renovation Project found no significant change in
the status of the exchangeable cations from that found in 1963 after
48 inches of wastewater had been applied. By 1966 the exchangeable
sodium percentage (ESP) in the wastewater treated areas had increased
with respect to the control area about 4-fold in the upper foot and
1% to 2-fold in the next four feet. However the maximum ESP value
in 1966 was only 3.3 and occurred in the upper foot of the 2-inch
per week treatment area. In 1966 exchangeable hydrogen, calcium and
magnesium still occupied 931 of the total exchange capacity in the
196
-------
upper foot and 95 to 96% in the next four feet. The sodium adsorption
ratio (SAR) value in the wastewater,
defined as: SAR =
Na+
Ca + Mg
ranged from 1.20 to 1.62 in the period 1963-66. Ion concentrations are
expressed as milliequivalents per liter. Agricultural Handbook No. 60
(1954) defines an irrigation water as having a low sodium hazard if the
SAR value is less than ten. On this basis the Penn State wastewater
would qualify as an excellent irrigation water.
Kline (1967) examined soil samples from the forested areas taken
in the fall, 1963; spring, 1964; and fall, 1965. He found larger
differences between 1963 and 1965 samples for exchangeable Na on the
treated plots but differences between control and treated areas in 1965
were similar to those found in 1963. Differences in exchangeable Na
between control and treated areas were significant to a greater depth
in the soil where two inches was applied weekly to red pine than where
only one inch was applied. Exchangeable Na was significantly greater
to a depth of five feet in the 2-inch red pine area but only to a depth
of three feet in the 1-inch red pine. In all cases exchangeable Na
remained below 0.5 m.e./lOOg and did not exceed an ESP value of 3.0.
There was no consistent pattern of differences in the other exchange-
able cations except that exchangeable Ca tended to be higher than the
control on the 2-inch red pine treated area and exchangeable K tended
to be higher than the control on the 1-inch red pine area.
The present report extends the information given by Edwards (1968)
through the soil sampling in 1969 and also reports on changes in the
status of exchangeable Mn, adsorbed chloride and boron, kjeldahl nitro-
gen and organic matter in the crop rotation area and in some of the
forested areas.
Summarized over the five soil depths (one foot increments to a
depth of five feet), Figure 1 indicates that in the corn rotation area
only in the case of exchangeable Mg and Na was there a significant
change due to wastewater treatment. The Mg increases occurred most
strongly in the upper foot. Below the second foot greater increases
occurred with the one-inch per week treatment than with the two-inch
treatment. Exchangeable Mg increased in a similar manner in the forest
areas.
The Na increases were also greatest in the upper foot and in this
upper zone it appears that both the one and two inch per week treat-
ments have peaked at a value of approximately 0.5 m.e. per 100 grams
197
-------
10
8
o»
O
O 6
D CONTROL
I INCH PER WEEK
2 INCHES PER WEEK
CALCIUM MAGNESIUM POTASSIUM SODIUM HYDROGEN
Figure 1. Exchangeable cations in soil samples from corn rotation
area which has been receiving 0, 1 and 2 inches of waste-
water, averaged over five one-foot depth intervals and
over six sampling years, 1963, 1965-69.
198
-------
of soil, equivalent to an ESP value of approximately 2.5 to 3.0%.
Samples taken in 1971 from the forested areas (Table 1) showed a range
in maximum exchangeable Na from 0.5 m.e.lOOg in the 1-inch red pine
area on the fine textured Hublersburg soil to 0.2 m.e./lOOg in the 2-
inch hardwood area on the sandy Morrison soil. These values were
equivalent, respectively, to ESP values of 2.9 and 3.2. Thus it
appears highly probable that with the present effluent quality, with
an SAR value less than 2.0, one need not be concerned about a sodium
hazard to soil structure and permeability.
With respect to the other principal exchangeable cations, K, Ca
and H, there were no significant treatment effects in the corn rota-
tion area (Figure 1). Since this area had been limed during the farm
management program prior to its use in the wastewater experiment a
sharp decrease of Ca with depth was present originally and this depth
effect has persisted. In the unlimed forest areas (Table 1) the depth
difference in initial exchangeable Ca content between the upper foot
and the deeper layers was not as great and some increase in Ca in the
upper foot occurred as a result of both the 2-inch and 1-inch per week
wastewater treatment. Effects of wastewater treatment on exchangeable
K in the forest areas were small and nonsignificant. Exchangeable H
in the forest area was inconsistently affected by wastewater treatment
except on the sandy Morrison soil which received the greatest amounts
of wastewater. On this site the exchangeable H in 1971 in the upper
foot was 13.7 m.e./lOOg in the control area and only 7.3 m.e./lOOg in
the wastewater area.
In the corn rotation area the small increase in exchangeable Mg
and Na were reflected in an increase in base saturation which in turn
was reflected in a significant increase in pH in the upper two feet
for both the 1- and 2-inch treatments.
Although manganese is not commonly measured among the exchangeable
cations it was included because of the possible effect of the increased
wetness on the solubilization of manganese by oxidation-reduction
reactions. The data indicated that differences due to wastewater treat-
ments were not significant in the more aerobic and less acid upper two
feet but that wastewater treatment did increase exchangeable Mn in the
next three feet, with the differences being significant at the 1% level
with the 1-inch per week and at the 5% level with the 2-inch per week
treatment. On the forested areas the one-inch wastewater additions
decreased the exchangeable Mn in the upper foot in the red pine area
and in the upper three feet in the hardwood area, however, exchangeable
Mn increased in the deeper layers. In the two inch treatment areas,
exchangeable Mn increased below the upper foot in the old field area
on the fine textured Hublersburg soil but decreased at all depths in
the hardwood area on the sandy Morrison soil. This situation conforms
to the nitrification-denitrification activity described for these two
199
-------
Table 1. Exchangeable cations in 1971 in soils at five depths from forest areas which have been
receiving 0 and 1 or 2 inches at weekly intervals.
o
o
Soil
Area Depth
feet
K
Ca
Mg Na
m.e./lOO grams
Wastewater
Red Pine^/ 1
2
3
4
5
0
0.1
0.3
0.1
0.5
0.4
1
0.3
0.1
0.3
0.4
0.4
0
1.8
1.9
1.3
1.6
1.4
1
3.1
1.7
0.7
0.5
0.4
0
0.4
1.2
1.5
1,5
1.5
Wastewater
Hardwood^ 1
2
3
4
5
0
0.1
0.3
0.2
0.2
0.3
1
0.2
0.3
0.3
0.4
0.4
0
1.0
1.2
1.1
1.0
0.8
1
1.9
1.1
1.0
1.4
1.1
0
0.2
1.2
1.7
2.1
1.7
applied
1
1.3
0.7
0.7
0.6
0.5
applied
1
1.1
1.5
1.4
1.2
1.3
H
m
wg/g
- inches per week
* 0
0.2
0.2
0.3
0.2
0.3
1
0.3
0.3
0.5
0.4
0.4
0
15.9
11.1
11.8
--
—
1
16.8
10.3
16.4
--
—
0
34.4
12.9
12.0
10.5
9.6
1
22.9
18.4
19.9
13.0
17.4
- inches per week
0
0.2
0.2
0.2
0.2
0.2
1
0.3
0.3
0.4
0.4
0.4
0
25.3
18.2
12.6
--
—
1
16.2
14.7
12.9
--
—
0
52.9
32.7
23.5
14.9
13.1
1
26.9
18.9
17.4
16.3
21.4
-------
Table 1. Continued.
Soil
Area Depth
feet
K
Ca
Mg Na
m.e./lOO grams
Wastewater
Old Fieldi/ 1
2
3
4
5
0
0.1
0.0
0.0
0.0
0.0
2
0.4
0.2
0.1
0.2
0.1
0
2.0
2.2
1.1
1.5
1.2
2
3.3
2.0
1.4
1.0
1.1
0
0.2
0.8
1.4
1.6
1.5
Wastewater
Bardwood^ 1
2
3
4
5
0
0.0
0.2
0.3
0.2
0.0
2
0.1
0.0
0.1
0.0
0.1
0
0.5
1.1
0.8
0.5
0.5
2
1.9
1.0
1.3
1.0
0.7
0
0.1
0.8
1.0
0.8
1.0
applied
2
1.7
1.3
1.2
1.4
1.4
applied
2
0.5
0.4
0.7
0.8
0.8
- inches per
0
0.2
0.2
0.2
0.2
0.2
2
0.3
0.3
0.3
0.3
0.3
- inches per
0
0.2
0.2
0.2
0.2
0.2
2
0.2
0.2
0.2
0.2
0.2
H
week
0
14.9
11.6
12.0
--
--
week
0
13.7
13.4
11.5
--
—
2
15.5
16.4
16.7
--
--
2
7.3
5.2
9.4
--
—
Mn
Pg/g
0
15.9
12.1
10.6
9.5
8.7
0
32.7
11.0
10.9
9.9
7.3
2
14.5
17.2
15.8
15.7
16.1
2
4.1
4.9
5.7
6.4
4.2
— On Hublersburg silt loam soil with irrigation during April-Nov. period since 1963.
2/
— On Morrison sandy loam soil with irrigation year round since No. 23, 1965.
-------
sites in the chapter by Kardos and Sopper (1973). The nitrate data
indicate that anaerobic conditions occur in the Hublersburg soil but
not in the Morrison. As a consequence of the reducing conditions,
oxides of manganese would be expected to become more soluble and
interact with the exchange sites in the Hublersburg soil. On the other
hand, the large decrease in exchangeable hydrogen in the Morrison soil
combined with its strongly aerobic character should result in a de-
creased solubility of the oxides of manganese.
Kardos and Sopper (1973) reported that chloride concentration in
the soil water was five-fold higher in the wastewater treated corn
rotation area than in the control area. Since the Hublersburg soil has
been shown to contain substantial amounts of free iron oxides (Hook,
Kardos and Sopper, 1973) and such oxides have a substantial capacity
for adsorbing anions, soil samples were extracted with hot, O.OS
to determine the adsorbed chloride content. The adsorbed chloride
increased with soil depth and the differences between the wastewater
treatments were not significant in the first foot but chloride in the
2-inch treatment at the second and third foot was significantly greater
than in the control and chloride in the fourth and fifth foot was sig-
nificantly different for all three wastewater treatments. The average
chloride content of the 2-inch wastewater area at the fourth and fifth
foot was approximately 40% greater than that of the control area. The
relatively large values in the control area compared to values found
in forested control areas by Kline (1967) are probably due to chlorides
from the muriate of potash in the commercial fertilizer which was
added annually to the corn rotation control area.
The amount of adsorbed chloride found in 1969 was surprisingly
large and the total for the five-foot depth, 1216 pounds per acre, was
approximately 3.8 times as much as was added in the 2-inch wastewater
treatment that year. Soils with less free iron oxides like the Morri-
son sandy loam which contains only one-half to one-third as much as
the Hublersburg silt loam (Hook, Kardos and Sopper, 1973), would not
retain as much chloride.
Other soil constituents which were examined were ammonium acetate
extractable boron which increased as wastewater treatment level in-
creased but the slight differences were not significant. Kjeldahl
nitrogen and organic matter were erratically variable from year to
year and differences were not significant.
In conclusion, changes in soil chemical quality have occurred as
a result of the wastewater treatments but these changes have been
relatively small and do not appear to pose any problems for the future.
202
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ACKNOWLEDGMENT
Research reported here is part of the program of the Waste Water
Renovation and Conservation Project of the Institute for Research on
Land and Water Resources, and Hatch Projects No. 1481 and 1809 of the
Agricultural Experiment Station, The Pennsylvania State University,
University Park, Pennsylvania. Portions of this research were support-
ed by funds from Demonstration Project Grant WPD 95-01 received ini-
tially from the Division of Water Supply and Pollution Control of the
Department of Health, Education, and Welfare and subsequently from the
Federal Water Pollution Control Administration, Department of the
Interior. Partial support was also provided by the Office of Water
Resources Research, USDI, as authorized under the Water Resources
Research Act of 1964, Public Law 88-379 and by the Pinchot Institute
for Environmental Forestry Research, Forest Service, USDA.
REFERENCES
Edwards, Ivor K. The Renovation of Sewage Plant Effluent by the Soil
and by Agronomic Crops. Ph.D. Thesis in Agronomy. 174 pp.
Sept. 1968. The Pennsylvania State University.
Henry, C. D., R. E. Moldenhauer, L. E. Engelbert, and E. Truog, 1954.
Sewage effluent disposal through crop irrigation. Sewage and
Industrial Wastes 26: 123-133.
Hook, James E., L. T. Kardos and W. E. Sopper. 1973. Effect of Land
Disposal of Wastewaters on Soil Phosphorus Relations. Proc.
Symp. on Recycling Treated Municipal Wastewater and Sludge through
Forest and Cropland. The Pennsylvania State University Press.
Kardos, Louis T. and W. E. Sopper. 1973. Renovation of Municipal
Wastewater through Land Disposal by Spray Irrigation. Proc. Symp.
on Recycling Treated Municipal Wastewater and Sludge through
Forest and Cropland. The Pennsylvania State University Press.
Kline, Glenn N. Effect of Sewage Effluent on the Chemical Properties
of the Soil in a Hardwood Stand, Red Pine Plantation and Open Old
Field. M.Sc. Thesis in Forestry. 78 pp. Sept. 1967. The
Pennsylvania State University.
Sanitary Engineering Research Laboratory. 1955. An Investigation of
Sewage Spreading on Five California Soils. Tech. Bui. 12. I.E.R.
Series 37. Sanitary Engineering Laboratory, University of Cali-
fornia, Berkeley, California.
United States Salinity Laboratory Staff. 1954. Diagnosis and Improve-
ment of Saline and Alkali Soils. U.S. Dept. of Agric., Agriculture
Handbook No. 60. L. A. Richards, Editor.
203
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FACTORS AFFECTING NITRIFICATION-DENITRIFICATICN IN SOILS
F. E. Broadbent
Department of Soils and Plant Nutrition
University of California, Davis
The oxidation of anmonium to nitrate in soils by micro-
organisms has been the subject of a great many research efforts
dating back to the beginning of scientific agriculture. The
nature of the nitrifying bacteria and their responses to a
broad range of environmental conditions have been amply documented
in the literature. It is not my intention to review this litera-
ture in any detail here today. Suffice it to say that nitrifying
bacteria are present in almost all soils and that they are
active over a wide range of moisture and temperature conditions
(Frederick, 1956; Justice and Smith, 1962; Reichman et al,
1966; Robinson, 1957; Tyler,ejt al, 1959).
/
Although the nitrifiers are obligate aerobes they are able
to function in oxygen concentrations substantially lower than that
of the atmosphere. For example, Amer and Bartholomew (1)
measured nitrification rates in a soil in relation to the oxygen
concentration of the ambient atmosphere. As expected, the
rate of nitrate production decreased with decreasing oxygen
concentration. About half as much nitrification occurred at
2.11 oxygen as at 20%. Below 0.4% oxygen nitrification essentially
ceased and at 0.2% there was a net loss of nitrate indicating that
denitrification was taking place. The activities of nitrifying
bacteria may also be curtailed by low pH which frequently may
result from acid produced by the nitrifiers themselves.
Although a number of heterotrophic microorganisms have been
found capable of oxidizing ammonium to nitrite and a few to nitrate,
present evidence indicates .that their activity is minimal in
relation to that of the autotrophic nitrifying bacteria. It can
be said for all practical purposes that nitrification does not
require organic materials as a source of energy.
Denitrification, also recognized quite early as a microbial
process, has not been studied quite so intensively as has nitri-
fication, but recent concern over the presence of nitrate in waters
has revived interest in it. The capacity of denitrifying bacteria
to convert a potential pollutant to an. innocuous gas which is a
normal atmospheric constituent suggest denitrification as an
ideal decontamination process. Whereas even such an eminent soil
microbiologist as Waksman (1932) once dismissed denitrification
204
-------
as "of no economic significance in well aerated not too moist
soils in the presence of moderate amounts of organic matter or
nitrate", today this process is being studied and utilized by
people representing a range of interest varying all the way
from engineering to medicine.
CONDITIONS FOR NITRIFICATION-DENITRIFICATION
Whereas nitrifying bacteria are autotrophic, denitrifiers
are heterotrophic. Nitrifiers are obligate aerobes, denitrifiers
are facultative anaerobes. Denitrification cannot take place in
the presence of any significant concentration of oxygen.
Nitrification is an energy yielding process, denitrification
an energy requiring one. It would seem then that by virtue of
their contrasting environmental requirements nitrification
and denitrification would be mutually exclusive processes. My
remarks here today will be concerned primarily with variations
on the theme that in fact nitrification and denitrification can
and do occur simultaneously in the same soil lake, pond or
stream, often in locations which are physically separated by
only very short distances.
The classical case is the rice paddy. Flooded soils are
known to develop two distinct layers after submergence; a surface
oxidizing layer only a few millimeters thick and a deep sursurface
layer which is in a chemically reduced state (Pearsall, 1950; Shiori
and Tanada, 1954). In the shallow surface layer of soil and in
the flood water above the soil nitrification readily proceeds be-
cause oxygen is present. However, if nitrate so formed diffuses
into the reduced layer, it is utilized as an electron acceptor
and nitrogen gas is released. Indirect evidence for this sequence
of events is provided by the data of Table 1 which shows that
when tagged ammonium sulfate was added to a flooded soil nitrogen
was lost if the surface of the flood water was in contact with
the atmosphere. However, when oxygen was excluded by substitution
of pure nitrogen gas for air in contact with the flood water
surface so as to prevent nitrification no loss of nitrogen from
the system occurred.
More direct evidence is given in Table 2, which shows that
nitrogen gas evolved from a flooded soil in an oxygen atmosphere
was derived from added ammonium sulfate. In a krypton atmosphere
virtually no evolution of nitrogen was observed, because nitrate
was not produced.
Greenland (1962) suggested the possibility of simultaneous
nitrification and denitrification in Ghanian soils several years
ago. In many situations both in soils and waters there exists
the possibility of oxygen depleted layers or microenvironments
205
-------
Table 1. Recovery of Tagged N from Flooded Maahas Clay In-
cubated in Air and in N2 after Addition of 100 ppm
N as (NH4)2S04i/
Incubation time Mty-N Organic N Total
days
0
14
30
0
14
30
ppm
Incubated in Air
97.0
76.2
47.8
Incubated in N2
97.0
68.9
41.5
ppm
1.1
15.3
18.0
1.1
31.8
58.2
ppm
98.1
91.5
65.8
98.1
100.1
99.7
I/ From Broadbent and Tusneem (1971)
Table 2. Tagged N in Various Fractions in Flooded Sacramento
Clay 24 Days after Addition of 100 ppm Tagged N
as
Atmosphere NIfy-N NC^-N Organic + N2 gas Total
clay-fixed N
Oxygen
Krypton
ppm
4.9
13.3
ppm
8.1
0.2
ppm
68.4
83.9
ppm
9.3
0.2
ppm
90.7
97.6
From Broadbent and Tusneem (1971)
where the rate of oxygen utilization exceeds the rate of diffusion
of oxygen to the site. For example, the vertical distribution of
oxygen in bodies of water frequently reflects the transition from
an aerated surface layer to anoxic conditions at some depth below.
Ammonia-containing water flowing into a lake, pond or artificial
lagoon might undergo nitrification near the surf ace and the nitrate
so produced could become subjected to denitrification through
206
-------
diffusion into anoxic zones, provided the organic matter content
were sufficiently high to support the growth of denitrifying
bacteria.
Meek e_t al. (1969) measured nitrate concentrations and E^
values as a function of depth in a cotton field of high water
table in the Imperial Valley, California, after application of
280 kg anhydrous ammonia per hectare. There was a reduction
in nitrate concentration and a drop in Eft as the soil solution
approached the water table. In another study with soil columns
with controlled water tables Meek et al. (1969) found that dis-
appearance of nitrate near the water table was associated with
decreases in redox potential, oxygen content of the soil solution,
and oxygen levels in the soil atmosphere. They concluded that the
quantity of soluble carbon carried down to the saturated zone was
also important.
EXPERIMENTAL EVIDENCE OF NITRIFICATICN-DENITRIFICATION IN SOILS
Denitrification in Soils of High Water Table
Much of the evidence of nitrification-denitrification and
related nitrogen transformations under field conditions has been
reviewed recently by Viets and Hageman (1971) who concluded that
much unwanted nitrate can be eliminated by managed denitrification
in treatment plants and on land that receives large amounts of
animal waste. Some of the difficulties attendant to obtaining
good quantitative estimates of the extent of denitrification under
field conditions are illustrated in an experiment in California
with Tulare sandy loam, a soil with a water table at about 4 ft
depth. Manure waste from a large dairy, after dilution with a
considerable volume of wash water, was passed through a separator
to remove solids, which were recycled by using them as bedding for
the cows. The liquid effluent containing 50 to 120 ppm soluble N,
almost entirely in the ammonium form, was spread on half-acre field
plots by three methods of flooding. Analyses of the distribution
of ammonium and nitrate nitrogen in quadruplicate plots showed that
nitrification was rapid, since the values for Nfy-N were very low,
below 3 ppm in most instances and never exceeding 5 ppm. Nitrate-N
values suggest denitrification below the surface layer, since there
was a tendency for nitrate concentration to decrease with depth.
However, this distribution can also be explained on the basis of
concentration of adsorbed ammonium from the dairy effluent near the
soil surface. Another difficulty is that field data of this kind
are very variable. For example, the coefficient of variation of
the data is 75%. Of particular interest are the low nitrate levels
in the intermittently flooded .plots, which received more nitrogen
than the single flooded plots. The alternation between flooded and
207
-------
unflooded conditions is particularly favorable to the nitrification-
denitrification sequence. For example, three rice soils at the
International Rice Research Institute kept in flood fallow lost no
nitrogen with no mid-season drying, but lost 120 to 320 kg N/hectare
with mid-season drying (Greenland, 1962).
In a laboratory experiment a 1-meter column of Tulare sandy
loam was set up to maintain the water table at 70 on depth while
collecting the effluent from the 100 cm depth. Dairy waste con-
taining 65 ppm N as tagged ammonium was applied in amounts equiva-
lent to 156 kg N per hectare (139 Ibs N/acre). Subsequently 0.001 M
CaCl2 solution was applied to the column at 5 to 7 day intervals in
increments of 12 cm and the column effluent analyzed for soluble
nitrogen containing the tracer. A total of 67 on of water passed
through the column. Uhtagged nitrate initially present in the soil
leached out quickly before anaerobic conditions were established.
Some tagged nitrate came through as a small pulse near the end of
the leaching period. Tagged nitrogen in the leachate was 1.97% of
the N added. Analysis of residual N in the soil at the conclusion
of the experiment indicated 15.4% of the applied nitrogen remained,
making an overall recovery of only 17.4%. Presumably the remainder
was denitrified.
A similar experiment with the very sandy subsoil found below
the water table in this same area was conducted to evaluate the
extent of denitrification in an environment low in available carbon.
Total organic C in the subsoil is 0.49%. Tagged nitrate equivalent
to 80 kg/hectare (71 Ibs/acre) was applied to the column, which was
then leached with 0.001 M CaCl2 intermittently over a period of six
weeks until a total of 45 cm effluent had been collected. In this
case 6.33 mg or 41% of the tagged nitrate passed through the column.
Residual tracer nitrogen in the column was not determined, but was
undoubtedly less than the 15.4% found in the experiment cited pre-
viously because of the very coarse texture of the subsoil.
Denitrification in Urisaturated Soils
Denitrification in saturated soil is, of course, to be expected.
A question of perhaps greater interest in whether denitrification
occurs to a significant extent in unsaturated soil profiles. One
can readily visualize conditions favorable for denitrification in
the micropores of an unsaturated soil, or even in the macropores at
depths where the diffusion of oxygen is too slow to meet the oxygen
demand. Again, the use of tracer sources of nitrogen provides an
answer to the question.
In a preliminary experiment tagged KN03 was placed at the sur-
face of a 1-meter column of Yolo fine sandy loam. The column was
208
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then leached intermittently with saturated CaSCty solution over a
two-•week period until the effluent contained no more tagged nitrate.
Saturation occurred only at the soil-air interface at the bottom of
the column. The elution curves indicated that 12.3 mg or 45.6% of
the tagged nitrate-N passed through the column. The gradual in-
crease in untagged N eluted from the column can be attributed to
mineralization of organic N. A more detailed accounting of nitri-
fication-denitrification in the Yolo soil was obtained in a larger
column containing 6 ft of soil and equipped with porous ceramic
probes at 1 ft intervals which allowed withdrawal of a small volume
of soil solution when desired. The soil was initially brought to
field moisture capacity, then tagged (Nffy) 2864 equivalent to 100 kb
N/hectare (89 Ibs/acre) was applied at a depth of 2 inches. There-
after 3 inches (7.5 cm) of water was applied at bi-weekly intervals
over a period of 28 weeks. One day after each water application
soil solution samples were taken at each depth and analyzed. After
8 weeks when effluent appeared at the bottom of the column the
leachate was regularly collected and analyzed. No significant con-
centration of nitrate penetrated below 5 ft and at no time did the
column effluent contain more than a trace of nitrate, either tagged
or untagged. An accounting of the tracer N (Table 3) indicates
that the soluble nitrogen which disappeared was largely denitrified.
Table 3. Balance Sheet of Tagged Nitrogen Added as
to a Free-Draining Column of Yolo Fine Sandy
Loam
Added initially
In column leachate
Removed in samples
Residual NHj and N0§
In soil organic matter
Not accounted for
(denitrified)
N
mg
182.0
0.0
10.7
2.3
12.8
156.2
Percent
of total
%
00
0
5.9
1.3
7.0
85.8
A striking contrast between a partly saturated and an unsatur-
ated column was observed with Venice peat, a very permeable soil
containing about 40% organic carbon. One column was free-draining;
the other had the water table maintained at 70 cm from the surface.
Elution curves indicated that 12.1 mg or 79% of the added nitrate-N
209
-------
was recovered in the effluent from the unsaturated column, whereas
0.06 mg or 0.41 of the added nitrate passed through the column with
a 30 on saturated layer. It may be observed that only about half as
much untagged N passed through the latter column as the unsaturated
one and that most of this amount was leached early in the experiment
before anaerobic conditions could be established. Denitrification
of untagged N undoubtedly occurred.
Direct Evidence of Denitrification of Unsaturated Soil
A shortcoming of all the experiments previously cited is that
none of them provides direct evidence of denitrification. Dis-
appearance of tracer nitrogen from a soil is convincing evidence of
loss, but the evidence that denitrification is responsible is only
presumptive. It would be desirable to provide a complete accounting
of all forms of nitrogen by direct analysis, but the experimental
difficulties involved in trapping and analyzing gaseous forms of
nitrogen without drastic alteration of the soil environment are
formidable. A major problem is that of detecting a relatively
small quantity of Na resulting from nitrate reduction in a vast
sea of atmospheric $2-
Direct evidence that some N£ in the soil pore space is indeed
the end product of the nitrification-denitrification sequence is
given in Tables 4 and 5. These give the composition of soil gases
and of the soil solution at various depths in a column of Hanford
sandy loam which was continuously leached with a solution of tagged
NIfyCl containing 50 ppm N. The column was designed to permit
control of the hydraulic head at all depths, which in practice
varied from -3 to -13 cm of water at various depths.
The data of Table 4 show depletion of oxygen and increase of
G02 and N2 with increasing depth. Nitrification occurred readily,
but may have been confined primarily to the top 28 on since NH| in
soil solution is very low below that depth. The presence of
absorbed NH| at lower depths is still a possibility. Decreasing
nitrate concentration with depth below 28 cm strongly suggests
denitrification. Unequivocal evidence is provided by the detection
of "N-tagged nitrogen gas at all depths below 8 cm.
210
-------
Table 4. Composition of the Soil Atmosphere at Various Depths in
a Column of Hanford Sandy Loam Continuously Leached with
a Solution Containing 50 ppm N as Tagged NH^Cl on Day 46.
Depth
on
8
28
48
68
88
Air- filled
pores
%
10.7
8.1
5.5
3.4
10.3
co2
%
0.77
1.65
2.05
3.03
3.18
°2
%
17.3
8.64
2.30
1.62
2.21
N2
%
81.9
89.7
95.6
95.3
94.6
Table 5. Nitrate-N and Nitrogen Gas Derived from Tagged NfyCl in
a Column of Hanford Sandy Loam on Day 46.
Depth
cm
8
28
48
68
88
NH+-N
ppm
16.3
3.7
0.5
0.0
0.0
NCyN
ppm
14.2
38.9
29.1
23.2
17.2
NCv-N tagged
I
79
87
91
89
85
N2 tagged
%
0.1
4.10
7.46
8.21
8.30
PRACTICAL SIGNIFICANCE OF NITRIFICATION DENITRIFICATICN
Although definitive field data are still scarce, it seems clear
that application of water containing nitrate or a potential source
of nitrate such as organic N or ammonium salts to the surface of a
soil will probably not result in that nitrate moving unimpeded to
the water table, having been diminished only by those quantities
which are intercepted by plant roots. Indeed, the well known poor
uptake efficiency of fertilizer nitrogen by crops, usually not much
better than 50% may be due in part to the stimulating effect of
plant roots on denitrification. Woldendorp e_t al. (1966) noted
211
-------
that 15-20% of-the nitrate passing through the rhizosphere may be
denitrified. A recent report by Kolenbrander (1972) of nitrate and
chloride concentrations in well water at a number of pumping stations
in Holland over a 45-year period provides some very interesting
evidence of widespread denitrification. The wells are located in
agricultural areas where the annual input of fertilizers has in-
creased substantially over the years. When the concentrations of
nitrate and chloride in the wells are plotted against average
annual fertilizer applications it was found that the proportion of
chloride which ended up in the groundwater was approximately 5
times the proportion of nitrogen. He concluded that low concentra-
tions of nitrate in deep-level groundwater point to the likelihood
of considerable further denitrification during infiltration of
drainage water into deeper strata.
In another recent study Pratt et al. (1972) determined nitrate
concentrations in saturation extracts oT soil in 3-meter profiles
of a long term fertility trail with citrus. Assuming no net im-
mobilization or mineralization and that the amount of N denitrified
was equal to the total N input minus that found in the soil minus
removal in the fruit, they found that up to 431 of the total
nitrogen input was lost.
Any precise attempt to follow the course of nitrification-
denitrification on a field scale requires a method of discriminating
between input nitrogen from fertilizers, wastewater, or other
sources, and that which results from decomposition of soil organic
matter, which typically contains 5 to 6% N. This can be accomp-
lished by use of 1% tagged materials, as illustrated in some of
the soil column data presented here, but the cost of materials
enriched with this isotope has been prohibitive for field work.
Recently the Atomic Energy Commission.1 s Los Alamos Scientific Lab-
.oratory has begun producing ^N-depleted material which can also
be used as a nitrogen tracer in natural systems, with the limita-
tion that the amount of dilution which can be tolerated is
substantially less than is feasible with highly enriched 1%
compounds. However, essentially pure 1% compounds are expected
to become available in ton quantities at costs which permit their
utilization in field trails. It is expected that experiments with
isotopically tagged materials in the natural environment, some of
which are already underway, will permit a complete accounting of
the fate of nitrogen applied to soils and will provide better
quantitative measures of nitrification-denitrification and related
nitrogen transformations under a variety of environmental conditions.
212
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REFERENCES
Amer, F. M. and W. V. Bartholomew. 1951. Influence of oxygen
concentration in soil air on nitrification. Soil Sci.
71, 215-219.
Broadbent, F. E. and M. E. Tusneem. 1971. Losses of nitrogen from
some flooded soils in tracer experiments. Soil Sci. Soc.
Amer. Proc. 35, 922-926.
Frederick, L. R. 1956. The formation of nitrate from ammonium
nitrogen in soils I. Effect of temperature. Soil Sci. Soc.
Amer. Proc. 20, 496-500.
Greenland, D. J. 1962. Denitrification in some tropical soils.
Agric. Sci. 58, 227-233.
International Rice Research Institute Annual Report 1969.
p. 139-140.
Justice, J. K. and R. L. Smith. 1962. Nitrification of ammonium
sulfate in a calcareous soil as influenced by combination of
moisture, temperature and levels of nitrogen. Soil Sci. Soc.
Amer. Proc. 26, 246-250.
Kolenbrander, G. J. 1972. Does leaching of fertilizers affect the
quality of groundwater at the waterworks? Stikstof 15, 8-12.
Meek, B. D., Grass, L. B., and A. J. MacKenzie. 1969. Applied
nitrogen losses in relation to oxygen status of soils. Soil
Sci. Soc. Amer. Proc. 33, 575-578.
Meek, B. D., Grass, L. B., Willardson, L. S. and A. J. MacKenzie.
1970. Nitrate transformations in a column with controlled water
table. Soil Sci. Soc. Amer. Proc. 34, 235-239.
Pearsall, W. H. 1950. The investigation of wet soils and its
agricultural implications. Emp. Jour. Expt. Agric. 18 (72),
289-298.
Pratt, P. F., Jones, W. W, and V. E. Hunsaker. 1972. Nitrate in
deep soil profiles in relation to fertilizer rates and leaching
volume. Jour. Environ. Quality 1, 97-102.
Reichman, G. A., Grunes, D. L. and F. G. Viets, Jr. 1966. Effect
of soil moisture on ammonification and nitrification in two
northern plains soils. Soil Sci. Soc. Amer. Proc. 30, 363-366.
Robinson, J. B. D. 1957. The critical relationship between soil
moisture content in the region of the wilting point and
mineralization of soil nitrogen. Jour. Agric. Sci. 49, 100-105.
Shiori, M., and T. Tanada. 1954. The chemistry of paddy soils in
Japan. Min. Agric. and Forestry. Japanese Gov't. Tokyo. 45 p.
Tyler, K. B., Broadbent, F. E. and G. N. Hill. 1959. Low tempera-
ture effects on nitrification in four California soils. Soil
Sci. 87, 123-129.
Viets, F. G., Jr. and R. H. Hageman. 1971. Factors affecting the
accumulation of nitrate in soil, water, and plants. Agric.
Handbook No. 43, ARS, USDA.
213
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Waksman, S. A. 1932. Principles of soil microbiology, ed. 2.
Williams and Wilkins Co., Baltimore.
Woldendorp, J. W., Dilz, K. and G. J. Kolenbrander. 1966. The fate
of fertilizer nitrogen on permanent grassland soils. Proc.
1st Gen. Mtg. Europ. Grassland Fed. 1965, 53-76.
DISCUSSION
Hanson: Was the 6 ft column of Hanford sandy loam a mixed soil
with organic matter all the way through the column
supplying an energy source for the bacteria?
Broadbent: Yes. It had organic matter all the way down. This is
extremely deep soil. The organic matter tails off to
about 30% of the surface layer at around 6 ft.
Hanson: Did you attempt to simulate the field soil in terms of
the profile?
Broadbent: Yes. This was an attempted simulation of field
distribution.
Overman: Obviously in turning the nitrogen cycle, you had to turn
the carbon cycle also. Do you feel that decomposing
organic matter in the upper profile will supply carbon
several feet down near the water table?
Broadbent: This, of course, depends on a great many soil properties.
But, in general, I would say yes.
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BIOTOXIC ELEMENTS IN SOILS
T. D. Hinesly and R. L. Jones
Department of Agronomy
University of Illinois
Application of stabilized municipal waste treatment plant re-
sidues on agricultural lands is the most economically viable solu-
tion to a growing solids disposal problem. Yet, it is a small pro-
blem from the standpoint of its utilization by agriculture. If all
municipal wastewaters generated in the continental United States
were given secondary treatment and the resulting solids stabilized
for utilization as a fertilizer and soil amendment, about 10 to 12
million dry tons of solids would be available each year. The
utilization of the solids in amounts just sufficient to meet the
needs of nonleguminous crops for supplemental nitrogen would
require an annual application of about 10 dry tons per acre. Thus,
not much over one million acres of land would be required at one
time to utilize the total continental United States production
of sludge solids. Only enough sludge solids would be available to
treat slightly more than 0.2 percent of the 465 million acres of
crop land or slightly less than 0.06 percent of the total 1,904
million acres contained in the continental United States. However,
because of its potential as a source of sorely needed stable organic
matter, municipal sludge exhibits its greatest value as a resource
when used as an amendment for the reclamation of surface-mined
lands. Since over 0.5 million acres of land strip-mined for coal
already exist in various states of devastation while another 0.5
million acres have been or will be stripped during the 20-year period
from 1964 to 1984, there is no scarcity of land which needs the nu-
trients and organic matter supplied in sludge. If properly used in
the reclamation of such lands, a discussion of the accumulation
of biotoxic elements in soils as a result of sludge recycling
would be purely academic. For example, unusual concentration levels
of chemical elements are released by weathering of shales in strip-
mine spoil banks where, in the absence of adequate contents of
organic matter, problems already exist which can be ameliorated with
applications of stabilized municipal sludges.
It is recognized that the solids from many small wastewater
treatment plants will probably continue to be recycled to crop land.
Also, the number of proponents for using land for the disposal or
renovation of partially treated wastewater appears to be growing.
Therefore, it is essential to review what is known with regard to the
accumulation of biotoxic elements in soils because in either case
the growing of crops will be part of the system. Nearly all chemical
elements, whether classed as essential or nonessential for the life
215
-------
processes of plants and/or animals can be considered as biotoxic at
some concentration levels. It is necessary to attempt to identify
those chemical elements which tend to be ubiquitously present in
relatively high concentration in municipal wastewaters and sludges
and might accumulate in soils in forms available to crop plants
at concentrations which may be injurious to plants or to animals
consuming the produce.
216
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MICRQBIAL HAZARDS IN DISPOSING OF WASTEWATER ON SOIL
D. H. Foster and R. S. Engelbrecht
Department of Civil Engineering
University of Illinois
Those who are considering land disposal of wastewater and
sludges are faced with a peculiar dilemma. On the one hand, they
may be applauded for recovering a resource and applying it in use-
ful ways - to irrigate crops and restore despoiled areas such as
strip mines. On the other hand, they are damned for spreading a
host of pollutants including pathogenic organisms around in the
environment. It is the purpose of this paper to explore the
public health dangers that may arise from the ultimate disposal of
wastes on land and to assess how well founded is the public ap-
prehension concerning health hazards. The paper is not intended
to be an alarming account of hypothetical hazards designed to down-
grade the potential benefits to be derived from land application of
wastewater and sludges. Rather, it is felt that engineers,
agriculturists, and governmental officials should be provided with
the type of information that will allow a rational, unemotional,
and realistic assessment of the potential public health problems
associated with the application of wastewater to land.
If one were to catalog the species of pathogens of man and
animals which could be present in raw wastewater, the list would
be a long one indeed. The tremendous variety of pathogens which may
occur in domestic wastewater are derived principally from the feces
and urine of infected human and animal hosts finding a direct
route into the sewer. Surface runoff in areas provided with com-
bined sewer systems will result in mammalian and avian pathogens
reaching the wastewater collection system. The relative densities
of the pathogens present in the wastewater will depend on a number
of complex factors; and, therefore, it is difficult to say with any
degree of assurance what the general pathogenic character of a par-
ticular wastewater will be. A thorough knowledge of the health
of the population in a given situation, the possibility of "disease
carrier" states in the population, an understanding of the sources
contributing to the wastewater, and a knowledge of the relative
ability of the pathogen to survive outside its host under a
variety of environmental conditions is necessary. The literature
can establish guidelines but each situation should be evaluated
individually.
217
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SURVIVAL OF PATHOGENS IN WASTEWATER
The principal pathogens present in wastewater may be divided
into four convenient groups (Table 1). Far more is known about
Table 1. Major Groups of Wastewater Pathogens
1. Bacteria
Salmonella
Shigella
Mycobacterium
2. Protozoa
Entamoeba Histolytica
Naegleria
3. Helminth Parasites
Ascaris
Ancylostoma
Necator
Taenia
Trichuris
4. Viruses
the occurrence of bacteria in wastewater than any of the other groups.
Massive outbreaks of bacterial disease due to sewage polluted
water have long been considered by many to be a thing of the past.
Yet one has only to look back as recently as 1965 to find a water-
borne bacterial epidemic of large proportions (Greeriberg and
Ongerth, 1966). Enough is not yet known to pinpoint the cause
of sporadic isolated cases of typhoid and other potentially water-
borne diseases so as to be able to definitely eliminate fecally
polluted water from the list of possible causes. Use of wastewater
for irrigation in the vicinity of isolated cases of enteric disease
could lead to the suspicion in the public's mind that the two are
somehow related, whether or not this is in fact the case. This sub-
ject should receive a closer examination.
Pathogenic Bacteria in Wastewater
Over 400 serotypes of the genus Salmonella have thus far been
identified (Salle, 1967). Members of this group have frequently
been isolated from feces, sewage, receiving waters and have even been
218
-------
found in finished drinking water supplies (Beard, 1938; Browning and
Mankin, 1966; Salle, 1967; and Seligman and Reitler, 1965). The
most important member of this group is Salmonella typhosa, the agent
of typhoid fever. Salmonella paratyphi and Salmonella schottmuel-
leri, the agents of paratyphoid, may also be present in wastewater.
Several other members of the Salmonella group have been pointed out
as causative agents of gastrointestinal disturbances and, as a
result, have been found in the feces of infected persons (Browning
and Mankin, 1966; and Seligman and Reitler, 1965). The survival
°f Salmonellae in wastewater is dependent on temperature, the
presence of organic matter and predation. Survival of typhoid
organisms in wastewater for more than 35 days at room temperature
have been reported by Wilson and Blair (1931), but generally
survival for shorter periods of time have been noted. Heukelekian
and Schulhoff (1935) found survival to be related to temperature
with 99 percent destruction of typhoid organisms in wastewater
occurring 6 to 10 days at both 22° and 37°C, while persistence
increased to 17 days at 2°C. Green and Beard (1938) found survival
to be up to 19 days and 27 days at indoor (20°C) and lower outdoor
temperatures (7°C), respectively. A 99.9 percent kill occurred
within 12 days under these conditions.
Others (Heukelekian and Schulhoff, 1935; and Rochaix, 1930)
have demonstrated that organic matter and the presence of predator
organisms can have a significant effect on the survival of
Salmonella bacteria. Mien organic matter in the form of feces or
urine were added to unpolluted water, growth of Salmonella was ob-
served. In the presence of competitive organisms, survival of
Salmonella is reduced. Survival in typical wastewater was reported
in one study to be from a few hours to 11 days while survival was
increased to as much as 20 months when competing organisms were
removed from sewage by sterilization (Rochaix, 1930).
In summary, it may be stated that survival of typhoid and
related organisms is relatively brief in wastewater. It should
be noted, though, that constant inputs of these organisms is possible
and it has been indicated that they were found in wastewater whenever
they were sought (Kabler, 1959; and Northing ton et_ al^, 1970).
Shigella organisms are one of the chief causes of bacillary
dysentery but fortunately their presence in wastewater is considered
rare (Wang et al, 1956). During a five-year study of irrigation
water in Colorado, no Shigella organisms were isolated despite frequent
isolations of Salmonella. When competitors were removed by ster-
ilization, Shigella organisms inoculated into wastewater increased
rapidly in numbers. However, in unsterilized stools they did not
survive long (Wang et al, 1956). Shigella flexneri was implicated
in a waterborne outbreak" of gastroenteritis involving the ir-
rigation of wastewater on pasture land (Browning and Mankin, 1966);
and thus, while its survival may be limited outside the human body,
the potential danger of Shigella in wastewater effluents applied
219
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to soil must be recognized.
Mycobacteria have been extensively studied in wastewater since
the time of the first findings of M. tuberculosum in feces around
1900. Tubercle bacilli appear to reach wastewater from feces con-
taining swallowed sputum of infected individuals and from un-
disinfected sputum in sanitoria wastewater. Muller (1959) reported
that raw wastewater contained 5 to 100 tubercle bacilli per liter
compared to 100 times as many Salmonella organisms in the same
volume. The tubercle organisms may be considered to be a regular
component of urban wastewater, even without known sanitoria
sources, since 90 percent of the raw wastewater samples examined
were positive for tubercle bacilli. Of chief concern with these
acid-fast bacilli is their ability to withstand a wide variety
of environmental conditions for prolonged periods. Musehold
(1900) exposed infected river water and wastewater to prevailing
outdoor environmental conditions and was able to recover viable
tubercle bacilli for up to 5 months. Others (Kroger and Trettin,
1950; Mannsfeld, 1937; and Rhines, 1935) have demonstrated sur-
vival times in sewage from 48 days up to 6-1/2 months. Greenberg
and Kupka (1957) reviewed the findings of several survival studies
and concluded that tubercle bacilli survived natural conditions in
sewage and other contaminated materials for relatively long periods
of time.
The majority of the studies carried out on Mycobacteria have
focused on the presence of M. tuberculosum in sanitoraawastes.
These studies may not provide a realistic picture of the danger of
infection from contaminated waters. While M. tuberculosum is per-
haps the most important potentially waterborne human pathogen of the
genus Mycobacterium, other species of this group are capable of
infecting man and animals. For example, granuloma may be caused
by M. balnei which may be present in chlorinated water used for
swimming pools (Cleere, 1960). Agents of bovine tuberculosis may be
present in milk and slaughterhouse wastes (Greenberg and Kupka,
1957). On the other hand, sanitoria wastes would generally be
expected to contain variable but higher concentrations of tubercle
bacilli than general domestic wastes and, therefore, may over-
estimate the importance of this disease agent. The quantity of these
organisms excreted by nonsanitoria patients is a matter of dispute.
While nearly all fecal samples examined from sanitoria patients
with pulmonary tuberculosis have been shown to contain viable
?!• tuberculosum (Jensen and Jensen, 1942), reports of these or-
ganisms in stools of apparently healthy individuals range from
positive findings in under 2 percent of fecal specimens examined in
one study to 21 percent in another (Laird et aL, 1913; and Wilson
and Rosenberger, 1909). Therefore, one couTd expect the tubercle
organisms to be present in domestic wastewater but in quantities which
may be expected to be highly variable.
220
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Pathogenic Protozoa in Wastewater
Protozoans pathogenic to man and capable of transmission by the
water route are Entamoeba histolytica. the agent of amoebic dysentery,
and members of the Hartmanella-Naegleria group, a free-living amoeba
causing meningo-encephalitis (Stringer and Kruse, 1970). The cyst
stage in the life cycle of protozoa is the principal means of dis-
semination of dysentery since motile amoebae are fragile entities,
dying quickly once they are outside the body (Noble and Noble,
1964). Cysts must be kept moist in order to remain viable for any
extended period in the environment. Each mature cyst, upon ex-
cysting, is capable of producing four motile amoebae. However,
laboratory studies have shown that as many as eight and possibly more
cysts may be required to establish an active culture containing
adult motile amoebae (Rudolfs et al, 1950). The efficiency of cysts
in producing pathogenic adults~cToes not, therefore, appear to be
great. Kott and Kott (1967) found the sewage in Haifa, Israel to
contain a maximum of nine E. histolytica cysts per liter with a
median value of four per litei\ Others have estimated that cysts
may occur in contaminated waters at levels not likely to be greater
than 5000 cysts per liter (Chang and Kabler, 1956). Since many
cysts found in wastewater are derived from nonpathogenic protozoans,
studies limited to E_. histolytica cysts probably are more representa-
tive of health hazards from wastewater application on land than
estimates of total cyst populations in wastewater. If a maximum of
20 cysts constitutes an infective dose (Rudolfs ejt al^, 1950), the
data of Kott (1967) would indicate that one infective dose may be
contained in 5 liters of wastewater. The actual cyst concentration
in wastewater will probably depend on the percentage of carriers
in the population. Therefore, the agents of amoebic dysentery should
be considered whenever cyst carrier rates in the population are
10 percent or higher (Northington et al, 1970)
Helminth Parasites in Wastewater
The ova of intestinal parasitic worms are excreted in the feces
of infected individuals and may be spread by a wastewater-crop-
human chain (Chang, 1965). Liebman (1965) reported ova of Ascaris
lumbricoides, the pinworm Oxyuris vermicularis^, the whipworm
Trichuris trichiura, and the tapeworm Taenia^saginata to be present
in wastewater at high levels. Cram (1943) noted that hookworm eggs
may also be present but others have rarely found the eggs of either
Necator americanus or Ancylostoma duodenale in wastewater (Aiba and
Sudo, 1965).Since hookworm larvae enter their host from fecally
contaminated soil, it could be disseminated by wastewater applica-
tion on soil. In moderate climates the human contribution of ova
to wastewater would appear to be no greater than 10 percent but may
reach 30 percent in subtropical regions such as the southern ex-
tremities of the United States (Liebman, 1965). The remainder of
221
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the ova are of animal origin. Various authors have reported 59
to 80 worm eggs per liter of sewage (Aiba and Sudo, 1965; and
Liebman, 1905). Translated into terms familiar to the engineer,
this could mean millions and perhaps billions of eggs reaching a
wastewater treatment facility daily. The eggs are generally
resistant to environmental conditions, having a thick outer cov-
ering to protect them against dessication (Noble and Noble,
1964). Fifteen days at 29°C were required in one study to
destroy 90 percent of Ascaris ova and they may survive 40°C for
up to 60 days (Komiya and Kutsumi, 1965; and Liebman, 1965). In
summary, it may be stated that a large quantity of a variety of
ova from parasitic worms may be present in wastewater and that
they possess a high degree of resistance to many environmental
stresses.
Viruses in Wastewater
Over 100 distinct serotypes of viruses (Table 2) may be
present in wastewater on a world-wide basis, regardless of climate
(Grabow, 1968). They are the smallest of the wastewater pathogens,
a fact which may have some bearing on their removal in wastewater
treatment and soil percolation.
Table 2. Viruses in Wastewater
Group
No. of Types Associated Diseases
Enterovirus
Polio 3
Coxsackie 30
Echo 31
Reovirus 3
Adenovirus 31
Infectious Hepatitus Unknown
"Viral" Gastroenteritis Unknown
Poliomyelitis
Aseptic Meningitis,
Myocarditis
Aseptic Meningitis,
Enteritis
Enteritis
Respiratory Illnesses
Jaundice
Gastroenteritis
Of the enteroviruses, evidence of waterborne disease trans-
mission exists only for poliovirus (Mosley, 1965). Of the other
viruses listed, infectious hepatitis and gastroenteritis warrant
special attention. The agents of both diseases have yet to be
222
-------
isolated but both are thought to be viral in origin since they
can be transmitted by bacteria-free filtrates of wastewater or
fecal suspensions (Dolin et al, 1971; Gordon et al, 1947; and
Neefe ejt al, 1947). The actual concentration ofthese agents in
wastewater is, of course, unknown but they appear to be relatively
prevalent if one can use their disease incidence as a yardstick.
From 1946 to 1960 there were 142 reported waterbome outbreaks
of gastroenteritis and 23 infectious hepatitis epidemics (Weibel
e£ aL, 1964). Together they involved nearly 19,000 disease
cases. These are only the reported epidemics and it is likely that
many more unreported waterborne epidemics and sporadic cases
occurred. Furthermore, disease is only a clinical minifestation
of establishment of a parasitic infection. It has been estimated
that far more viral infections occur than actual disease incidences
(Mosley, 1965). Clearly then, a large quantity of virus may be
present in the wastewater, and surviving the multiple treatment
and natural barriers in their path to finally result in disease.
The initial concentration in wastewater must be high for the chance
contact of man and virus to have any chance of successful infection.
Viruses as a group are generally more resistant to environmental
stresses than many of the bacteria. For example, Clarke et al
(1964) compared the survival of viruses in wastewater to three
enteric bacteria. Survival of virus in wastewater at 20°C was
longer in all cases than the bacteria studied and ranged from
23 to 41 days. The time required for 99.9 percent reduction of
viral numbers reportedly ranges from 2 to 100 days for various mem-
bers of the enteric virus group (Akin elt al, 1971). Virus survival
was inversely related to temperature. OtHer factors, such as pH
value, which could conceivably affect virus survival have not been
thoroughly investigated.
It has been estimated that the virus concentration of raw
wastewater is approximately 7000 units per liter (Clarke, et al,
1964). Kelly and Sanderson (1960), using a semiquantitative techni-
que for virus recovery, reported the virus density in raw waste-
water to be 4000 units per liter during the warmer months of the
year and 200 units during the colder months. Shuval (1969) recently
found the virus density in raw wastewater in five Israeli cities
to average 1050 virus units per liter and ranged from as few as
5 to as many as 11,184 units per liter. Lund et al (1969) ob-
served maximum values of 100,000 virus units per liter. One
problem in interpreting these various findings is that viruses are
rather fastidious in their growth requirements. The techniques for
sample concentration, the host cell system, and the type of culture
technique used will all be selective with respect to the viruses
enumerated. No universal procedure or system is presently available
for cultivation of all viruses. It is likely, therefore, that many
of the investigations of virus density in wastewater have not
included all viruses present due to the selectivity of techniques
employed. In addition, many of the previous studies involved
223
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centrifugation or filtration of samples to remove participates
associated with the wastewater before enumerating the viruses pre-
sent (Lund et_ al, 1969). Lund's work did not involve these forms
of sample treatment and the higher values for virus density ob-
tained indicate that other workers may have lost many viruses in
the sediment they removed. If Lund's values for the virus density
of raw wastewater are correct, it is readily apparent that
tremendous quantities of virus arrive at wastewater treatment
plants daily.
REMOVAL OF PATHOGENS IN WASTEWATER TREATMENT PROCESSES
In order to assess the importance of pathogens in land ap-
plication of wastewater and sludges, one must not only know how
many are present in the raw wastewater or in the settled sludges,
but also the efficiency of various treatment processes in removing
or destroying them. The degree of treatment and types of unit
operations used in treating wastewater for application on soil
may vary and, therefore, the approach adopted here will be to
discuss each treatment operation or process separately. It should
be noted that much of the information available in the literature
on the efficiency of various treatment steps is derived from labora-
tory studies. Where available data exists comparison of laboratory
and field data would suggest that laboratory research often over-
estimates the efficiency that can be obtained in the field.
Therefore, some mental adjustment of laboratory data to be presented
may be appropriate.
Primary Sedimentation
Primary treatment of wastewater appears to exhibit a variable
efficiency in removing pathogens depending in part on the type of
pathogen studied (Table 3). Bloom et_ al (1958) isolated Sal-
monellae from six of seven different primary effluent samples. The
raw sludge also contained members of this genus with 19 of 20 samples
being positive for Salmonella organisms. McKinney et al^ (1958)
were unable to isolate S. typhosa from raw wastewater sludge.
Muller .(1959) found tubercle bacilli to be reduced by 50 percent by
primary sedimentation while Kelly et aL (1955) found a 57 percent
reduction. Reductions of tubercleTTacilli from 48 to 54 percent
during settling of raw sewage have been reported by others
(Heukelekian and Albanese, 1956). Considerable quantities of the
Mycobacterium may occur in the sludge produced in primary sedi-
mentation.Framer et al_ (1950) demonstrated 67-fold concentration
of tubercle bacilli in raw sludge as compared to that in the
influent wastewater. These studies would indicate that bacterial
pathogens are ineffectively removed from wastewater by primary
224
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treatment and, furthermore, the process produces sludges which
constitute a hazard without further treatment.
Table 3. Removal of Pathogens by Primary Treatment
Pathogen Reported Removal Efficiency
Salmonella 15±/
Mycobacterium 48 to 57
Amoebic Cysts No. reduction in 3 hours
Helminth Ova 72 to 98
Virus 3 to extensive removal
I/ Based on Frequency of Isolation
Removal of amoebic cysts by primary treatment has not been
extensively studied. Cram (1943) observed that 3 hours settling in
laboratory units had little effect on the density of E. histolytica
cysts in the supernatant. Eggs of parasitic worms were removed
more effectively. Cram's work showed that some hookworm eggs
still remained in the upper 1/3 of a laboratory settling basin
after 2-1/2 hours sedimentation. Ascaris ova, on the other hand,
appeared to settle within 15 minutes with the eggs concentrated
in the sludge. Taenia saginata ova have been reportedly removed
to the extent of 98 percent within 2 hours (Newton ejt al, 1949).
Others have, on the other hand, indicated removals as low as 72
percent during sedimentation (Greenberg and Dean, 1958). It
may be concluded that primary sedimentation for 2-1/2 hours or more
cannot be depended upon to produce effluents free of parasitic worm
ova or amoebic cysts. Additionally, primary sludges may contain
significant quantities of helminth ova (Aiba and Sudo, 1965).
The majority of the studies involving the removal of viruses
by primary treatment would indicate that few viruses are removed
during this operation. Poliovirus 1 seeded into raw wastewater
was removed only to the extent of 3 percent following 3 hours of
settling (Clarke e_t al, 1961). In another study isolations of
virus from primary efTluent were more frequent compared to isolations
in the primary influent (Mack et_ al, 1962). On the other hand,
Bush and Isherwood (1966) suggested" that the survival of mice
inoculated with primary effluent indicated extensive removal in the
primary clarifier since large quantities of virus were known to
be present in the influent. Laboratory studies where wastewater has
been seeded with virus, such as that of Clarke et^ al^ (1961), may
225.
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not reflect removal of viruses that would be associated with sewage
solids in natural systems. Many studies of field size units have
involved filtering out solids from influent samples prior to assaying
and would, therefore, not reflect virus particles associated with
wastewater solids. Lund's (1969) work demonstrated conclusively
that many virus particles are associated with wastewater solids.
Indeed, the increase in virus seen in a primary settling tank, as in
the study cited above, may reflect the release of virus from raw
sludge. It may well be then that removal of virus in primary
treatment has been underestimated.
Secondary Treatment
Biological treatment appears to be quite efficient in removing
wastewater pathogens but does not produce an effluent which is
pathogen free (Table 4). Beard (1938) reported that S. typhosa
Table 4. Removal of Pathogens by Secondary Treatment
Reported Removal Efficiency
Pathogen Group Activated Sludge Trickling Filters
Salmonella
Mycobacterium
.Amoebic Cysts
Helminth Ova
Virus
%
96 to 99
Slight to 87
No Apparent Removal
No Apparent Removal
76 to 99
t
84 to 99.9
66 to 99
11 to 99.9
62 to 76
0 to 84
was reduced in density by 96 percent in 6 hours and 99 percent in
8 hours aeration in activated sludge units. When sterile sewage
was inoculated with Salmonella and aerated an increase in density
was noted indicating that biological action and not aeration per se_
was responsible for the reductions seen in normal waste treatment
(Greenberg and Beard, 1938). M. tuberculosum was affected little
by aeration for 24 hours (Pramer et al, 195tiJ. Others have
reported similar failure of the activated sludge treatment to
completely remove tubercle bacilli even when the aerobic bacterial
content had been reduced to 0.2 percent of its original numbers
(Jensen and Jensen, 1942). Heukelekian and Albanese (1956) observed
an 87 percent reduction in tubercle bacilli following 6 hours aeration
226
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in activated sludge units. Increasing the aeration period to 24
hours affected only another 1 percent removal. The bacilli
were rapidly transferred to the sludge phase apparently by
adsorption to the settling particles resulting in a sludge tubercle
bacilli concentration at the end of 6 hours that was 13 times
greater than the supernatant liquor. Therefore, the sludge
should also be considered a potential hazard and could infect soil
with tubercle bacilli if applied to land without further treat-
ment.
Trickling filters were found to reduce the concentration of
paratyphoid organisms by 84 to 99 percent (Kabler, 1959). Low
rate trickling filters were apparently capable of removing up to
99.9 percent of S^. typhosa while a 95 percent reduction was accom-
plished even at loadings of 12 mgad (Lund et al, 1969)." A 99 per-
cent reduction in M. tuberculosum by trickling filters has also been
observed (Pramer et al, 1950).Oh the other hand, only a 66 per-
cent reduction hasTjeen noted (Heukelekian and Albanese, 1956).
It should be pointed out that the removal in activated sludge
was higher by more than 20 percent than in trickling filters in
this same study. Activated sludge treatment has no apparent effect
on E. histolytica cysts, even when aeration was extended to 48
hours (Cram, 1943). It should be recalled that primary sedimenta-
tion also seemingly produces no reduction in cyst numbers so that
cyst densities in the effluents of activated sludge plants may change
little from those in the influent. Removal varied from 88 to
99.9 percent in laboratory scale trickling filter plants in one
study and another full scale study has reported 11 to 50 percent re-
duction in cyst "densities in wastewater (Cram, 1943; and Kott and
Kott, 1967).
Ova of intestinal parasites are apparently not affected by the
activated sludge process (Cram, 1943; and Newton ejt al, 1949); and,
in fact, the literature indicates that activated sluHge mixed liquor
provides an excellent hatching medium for the eggs (Kabler, 1959).
Trickling filters, on the other hand, reduced ova concentrations
62 to 76 percent but may produce live larvae in the effluent when
the filters slough off surface growth (Newton e_t al, 1949). In
general, activated sludge appears to be ineffective in removal
of both cysts and ova; and, while trickling filters are somewhat
more efficient, they still pass significant portions of the incoming
pathogens out the effluent. Secondary settling will not affect
much further reduction of cysts; and, therefore, the final
effluent will contain these pathogens (Kott and Kott, 1967).
Final clarifiers could be expected to bring about similar removals
of parasitic worm ova as observed in primary sedimentation, i.e.
70 to 90 percent.
Laboratory activated sludge units seeded with virus have shown
96 to 99 percent removal of Coxsackie A9 virus and lesser efficiency
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with Poliovirus 1 (Clarke et al, 1961). Since many virus particles
are apparently naturally boun.cT"to solids, studies of activated
sludge systems seeded with virus may not be representative of
"real world" situations. Lund (1969) estimated that 95 to 99 per-
cent of viruses were removed by activated sludge on the basis of
frequency of isolations in the influent and effluent. Studies
of full scale wastewater treatment following community-wide
administration of oral polio vaccines showed 76 to 90 percent
removal of virus by activated sludge (England et al, 1967). Since
swab samples for naturally occurring viruses were positive for 90
to 93 activated sludge effluent samples, one may conclude that
viruses are generally present in the effluent.
Theios eit al (1967) concluded that activated sludges was more
efficient in removing virus than trickling filters based on studies
of full scale plants during a polio vaccine campaign. In another
study, the frequency of isolations in the influent and effluent
of trickling filters has been reported to be approximately equal
(Kelly and Sanderson, 1959). Shuval (1969) found trickling filter
efficiency to be 0 to 84 percent in removing viruses. Trickling
filters cannot be depended upon to produce a significant reduction
in viruses.
Anaerobic Digestion of Sludges
Large quantities of pathogenic bacteria, helminth ova, and
viruses can be found in sludges from primary and secondary clari-
fiers. Smaller quantities of amoebic cysts may also occur. These
raw sludges would constitute a hazard if disposed of on land without
further treatment. Anaerobic digestion at 30 to 35°C accomplishes
a considerable reduction in the organic content of the sludge and may
result in destruction of pathogens. !5. tvphosa survived to the
extent of 0.3 to 17 percent after only 12 hours in batch digestion
studies (McKinney et_ al, 1958). Use of continuously fed digesters
demonstrated reductions of 84 to 92 percent for 6 and 20 days digestion,
respectively.
Mycobacteria may survive a digestion period of more than 35
days in laboratory units and were reduced from 9700 to 3000 per ml
in field scale units (Heukelekian and Albanese, 1956). No
appreciable decrease in numbers occurred in the dried digested sludge
even after 25 days drying. Others have observed a 90 percent
reduction in tubercle bacilli during digestion (Pramer et al, 1950).
Reports of survival of tubercle bacilli in dried sludges exposed to
natural conditions indicate survival times of from 6-1/2 months to
2 years (Jensen and Jensen, 1942; and Mttller, 1959).
The data reviewed by Chang (1965) on survival of helminth ova
in digesters indicated that at least one month detention is necessary
228
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for their destruction. Ascaris ova are not affected by 3 months
digestion and 10 percent remain viable even after 6 months (Cram,
1943). Cysts, though probably not present in sludge in large
quantities, are readily destroyed in 10 .days at 30°C. Poliovirus
has been isolated from digester sludge despite exposure to 50°C
for up to 50 to 60 days. No virus was isolated from digested sludge
in another study where only 2 samples were examined (Kelly and
Sanderson, 1959). When sludge samples from a digester seeded with
a swine virus were fed to germ free piglets, no indication of
piglet infection was observed for all samples taken after the fourth
day of digestion at 34.5°C (Meyer et al_, 1971). Coxsackie B5
survived thermophilic anaerobic digestTon for 30 days while bacterio-
phage survived mesophilic digestion for 4 months (Grigoryeva e_t al,
1969). It is apparent that some viruses are capable of with-
standing sludge digestion for long periods while others are not.
Determination of the range of survival of viruses representative of
each of the major virus groups during digestion is required before
potential hazards arising from application of liquid and dried di-
gested sludges on land can be fully assessed.
Disinfection of Wastewater
The disinfection of wastewater is perhaps one of the most
thoroughly studied areas with respect to the reduction of numbers of
pathogenic organisms by waste treatment processes. This is as it
should be, since final effluent disinfection is the last line of
defense before the wastewater and the pathogens it might contain are
placed in the environment. Unfortunately, much of the research has
been ill-defined with little appreciation of the fact that a dis-
infectant may react with components of the system other than the
pathogens; and, thus, change its potency for pathogen destruction.
With chlorine, the most commonly used wastewater disinfectant in the
united States, the initial dosage, the pH value, contact time,
temperature, quantity of nitrogenous compounds present, and their
nature, i. e. whether they are organic or inorganic, should be
stated in order to interpret results of chlorination experiments;
all these factors will have impact on the disinfecting capability
of chlorine. Since much of this information is not available in
many of the studies to be reviewed here, only general statements of
relative resistance will be given.
Kabler (1951) found that resistance of E_. coli and Pseudomonas
aeruginosa to free chlorine at neutral pH values was approximately
the same but less than that for £. typhosa and Shigella dysenteriae.
Resistance to combined chlorine was comparable between these organisms
but was considerably greater than that found for free chlorine.
Survival with 0.3 mg/1 of free chlorine was negligible while under
the same conditions the test organisms were able to completely
survive contact with 0.3 mg/1 of combined chlorine. A reduction in
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temperature from the 20 to 25°C range down to 2 to 6°C resulted in
a further loss of bactericidal action of combined chlorine.
Mycobacteria have layers of lipids and mycolic acids in their cell
walls which cause a higher degree of chlorine resistance in this
group of bacteria (Grabow et al, 1969). A review of over a dozen
different wastewater disinfection studies led Greenberg (1957)
to conclude that a combination of biological purification and
effluent chlorination with a chlorine dosage of 20 mg/1 with a
2 to 3 hour contact time or a chlorine residual of at least 1 mg/1
following a 1 hour contact was necessary to destroy tubercle
bacilli. Chlorine dosages up to 340 mg/1 and 2 hour contact times
have been found necessary to destroy Mycobacteria in other studies
(Musehold, 1900). Higher chlorine residuals and longer contact
times are thus required to inactivate tuberculosis organisms in
comparison to other bacterial pathogens.
Cysts are apparently the most chlorine resistant waterborne
pathogens. When the cysticidal properties of 2 mg/1 each of free,
combined inorganic, and combined organic chlorine residuals were
compared in one study, it was observed that a 10 minute and 40 minute
contact time was necessary for a 99.9 percent kill for the first
two categories of compounds while organic chloramines failed to
destroy more than 50 percent of the cysts even after 100 minutes
of contact (Stringer and Kruse, 1970). Since wastewater effluents
may contain organic and inorganic nitrogenous compounds, break-
point effluent chlorination may be required in order to destroy
cysts present in secondary effluents.
The reported response of viruses to chlorine varies widely
depending on the condition used in a given study and the type of
virus examined. Poliovirus 1 and Coxsackie A2 are much more resis-
tant to chlorine than coliforms while adenovirus 3 is apparently
more sensitive. Infectious hepatitis virus is able to survive 30
minutes contact time with 1 mg/1 total residual chlorine in fecal
suspensions if no other treatment is provided. Liu (1971) studied
the chlorine resistance of 20 human enteric viruses seeded in
Potomac River water. The least chlorine resistant virus, Reovirus
1, required only 2.7 minutes contact with 0.5 mg/1 of free
chlorine for 99.99 percent inactivation. Coxsackie AS and
Echovirus 12 required 53.5 and 60 minutes contact, respectively,.
to reach the same level of inactivation under these conditions.
Combined chlorine has very little viricidal capability (Kruse
et al, 1970). It is evident that the resistance of viruses to
cElorine is quite variable. Since more than 80 viruses have not
been subjected to detailed studies of their resistance, the
disinfection conditions necessary to kill all viruses in wastewater
230
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effluents is still an open question. It would appear that as with
cysts, a free chlorine residual at a contact time of at least 1/2
hour is necessary to destroy many of the viruses.
PA1HOGENS APPLIED TO SOIL
Table 5 is an attempt to summarize the data on the removal of
pathogens in wastewater. Where definitive data do not exist for
removal efficiency at a particular treatment step, values have
been assumed based on any available information. Removal percent-
ages assumed are given in parentheses. A uniform disinfection
efficiency of 99.9 percent has been assumed. If the conditions
necessary to destroy the more chlorine resistant pathogens were
applied to wastewater, kills of relatively sensitive organisms
such as Salmonella, greater than 99.9 percent would be obtained,
thus further reducing the quantity of some pathogens. However,
since the survival time of the remaining organisms may be quite
long in soil, continuous application of wastewater onto soil could
result in an accumulation of pathogens. An equilibrium value could
be reached where die-off and removal through percolation and runoff
is balanced by the daily input of new pathogens. The longer the
survival time in soil the greater the equilibrium level. S. typhosa
reportedly survive up to 85 days in soil but with soils whTch have
poor moisture retaining power, survival in periods of drought may
be as brief as 2 days (Beard, 1938; and Mallmann and Litsky, 1951).
With continuous application of wastewater soils may not have
sufficient opportunity to dry out; and, therefore, survival of
Salmonella could be prolonged. Mycobacteria can survive dry
•conditions in soil for more than 150 days and survival times as
long as 15 months have been reported (Greenberg and Kupka, 1957).
While protozoan cysts are sensitive to dessication, Ascaris and
Ancylostoma ova remain viable for long periods and have withstood
conditions where the moisture content of soil was less than 6 percent
and temperatures above 40°C for 60 to 80 days (Cram, 1943). Viable
Ascaris eggs have been recovered up to 170 days under more favor-
able conditions. Little definitive information on the survival
of virus in soil exists, but one could expect it to be of the same
order of magnitude as survival in wastewater where persistence as
long as 100 days has been reported (Akin e_t al, 1971).
If one accepts the figures given in Table 5 as reasonably
accurate estimates of the possible quantities of pathogens that may
be applied to land from chlorinated effluents, then one might con-
clude that considerable numbers of pathogens could be placed in the
environment. The density of organisms on land will be even greater
if they accumulate in the soil. Any degree of treatment less than
secondary treatment in combination with free residual effluent
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Table 5. Estimated Wastewater Pathogens Applied to Soil
Pathogen
Salmonella
Mycobacterium
E. histolytica
Helminth Ova
Virus
Number of Organism Per Million Gallons
Primary Secondary
Wastewater Effluent Effluent Disinfection I/
2 x 1010
2 x 108
1.5 x 107
2.5 x 108
4 x 1010
1 x 1010 (50%)^
1 x 108 (50%)
1.3 x 107 (10%)
2.5 x 10 7 (90%)
2 x 1010 (50%)
5 x 108 (95%)
1.5 x 107 (85%)
1.2 x 107 (10%)
5 x 106 (80%)
2 x 109 (90%)
5 x 105
1.5 x 104
1.2 x 104
5 x 103
2 x 106
Organisms
Applied
Per Acre
Per Day £'
3.9 x 103
1.2 x 102
9.3 x 101
3.9 x 101
1.6 x 10
I/ Conditions sufficient to yield a 99.9% kill
2/ Applied at a rate of 2 inches per week
3/ Estimated pathogen percentage removal efficiency of the treatment
-------
disinfection will result in greater quantities of pathogens
being applied to soil. If, for example, the wastewater is not
chlorinated the quantities of pathogens applied will be 3 logs
greater. Yet are these quantities sufficient to result in
much danger of disease transmission? The density of pathogens with
the application of chlorinated secondary effluent for any one of the
pathogens cited would not be greater than 1 viable pathogen per
four square feet per day. At the other extreme, the total patho-
gen load for unchlorinated secondary effluent is approximately
460 per square foot per day.
PUBLIC HEALTH HAZARDS
Several studies have attempted to assess the hazards involved
in the application of wastewater on land and provide interesting
comparisons to the figures in Table 5. Basically, the studies
have been concerned with 1) hazards from aerosols in spray irrigating
the wastewater on land, 2) contamination of edible crops, and
3) contamination of water from runoff and percolation.
Aerosol generation from spray irrigation could produce particles
of a size which would either pass into the lungs or pass from the
bronchi to the pharynx and into the intestine (Sorber and Guter,
1972). Infections such as Salmonellosis could therefore result
from such exposure. However, enteric bacteria such as Salmonella
are apparently not long lived as unprotected aerosols. Tubercle
bacilli are resistant to drying and, therefore, should survive in
the atmosphere as aerosols for extended periods. Greenberg (1957)
felt the use of sewage sprays containing Mycobacteria to be es-
pecially dangerous. Inhalation would place the bacilli in the
location where they can do the most damage as causative agents
of pulmonary tuberculosis. Viability of airborne virus is
relatively long. For example, in one study the majority of polio-
virus aerosols persisted for more than 23 hours when the relative
humidity was high (Walker, 1970). Reports of disease incidences
resulting from contact with aerosols from spray irrigation have
not appeared in the literature but this area should warrant further
study.
Crop contamination research has mainly focused on vegetables
which normally are eaten raw such as tomatoes, radishes, etc. Other
studies have dealt with irrigation of pasture land for grazing of
livestock. When tomatoes were field sprayed with feces or waste-
water containing Salmonella and Shigella, survival of these organisms
did not exceed 7 days (Rudolfs et al, 19"51). However, a radish
patch to which tubercle bacilli contaminated wastewater sludge had
been applied yielded viable bacilli after 3 months exposure to the
elements (Musehold, 1914). Rudolfs1 (1951) statement that cessation
of application of fecally contaminated fertilizer one month before
233
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harvesting offers a margin of safety against bacterial disease
would not seem to apply to M. tuberculosun. E_. hystolytica cysts
are quite sensitive to dessication and do not survive longer than
3 days of dry weather when applied to crops such as lettuce and
tomatoes (Rudolfs et al, 1951). Immature Ascaris ova were not
found to survive fTelcT conditions longer than 35 days (Rudolfs
et_ al, 1951). Rudolfs noted that exposure of immature ova to the
prevailing environmental conditions retarded their development into
motile embryos. It must be pointed out, however, that studies
of Cram (1943) and others (Kabler, 1959) have shown that the
secondary waste treatment environment provides an excellent medium
for development of ova. It is likely, therefore, that mature
rather than immature ova would be present in large quantities in the
effluent. If this is the case, Rudolfs' work may have underesti-
mated the ability of Ascaris ova to survive and mature under field
conditions. In general, there appears to be a danger of pathogen
contamination of vegetables to be eaten raw if wastewater is
applied to fields within 2 to 3 months of harvesting. If this is
the case, it could limit its usefulness for crops such as lettuce
and radishes which have short growing seasons.
Irrigation of fields for forage crops has produced interesting
results which could eliminate some of the concern expressed about
contamination of vegetables. Grass sprayed with 4 x 10° tubercle
bacilli per square foot was fed to guinea pigs with no apparent
effects (Greenberg and Kupka, 1957). Heavier inoculations, how-
ever, resulted in deaths in both guinea pigs and bovine test
animals. The predicted values for tubercle bacilli applied to
land in unchlorinated effluents obtained from the data of
Table 5 (i.e.. 2.7 x 10^ bacilli per square foot) would indicate
that the daily pathogen load would be at least six orders of magni-
tude below the levels which had no effect on guinea pigs. The danger
to man and animals from ingestion of tubercle bacilli from crops
irrigated with wastewater would appear to be slight.
!'•
The movement of bacterial and viral pathogens in percolation
and runoff has been extensively reviewed in the literature (Krone,
1968; Krone et al, 1958; and Romero, 1970). Generalizations are
difficult, but it appears that virus and bacteria movement in soils
is related directly to the hydraulic infiltration rate and inversely
with media particle diameters. Factors influencing bacterial and
viral inactivation in soil such as oxygen tension, temperature,
and the presence of competing organisms and antimicrobial agents
will also be determining variables. Other factors which have an
influence on adsorption phenomena in soils such as pH value,
multivalent cation concentration, and clay content of the soil will
influence removal of pathogens, particularly virus, in soils. The
majority of the studies reviewed indicate that the upper layers of
soil are most efficient in removing bacteria. At Lodi, California,
colifoitn levels were observed to decrease to below drinking water
234
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standards within 7 feet of the surface (Romero, 1970). Other
research demonstrates that 92 to 97 percent of applied coliforms were
retained in the uppermost 1 on of agricultural soil. Even in the
coarse gravel-sand used at Santee, California, most applied bac-
teria did not travel more than 200 feet. Cram (1943) reported
Ascaris eggs would pass a 12 inch layer of sand but were removed
by 24 inches as were hookworm ova and E_. histolytica cysts.
Drewry (1968) studied removal of viruses in a variety of soil
lysimeters and concluded that no column studied was saturated with
virus over more than 2 cm. Up to 5 percent of the applied virus
passed the columns but generally removals were quite high, parti-
cularly in the upper layers. Virus seeded into the influent of
the Santee percolation beds could not be recovered from samples
concentrated by swabs located in an observation well 200 feet
from the influent application site (Akin et_ al, 1971). It is
likely, therefore, that pathogens do not travel to any great extent
in soils and are removed principally in the upper layers. Even
where organisms do travel up to 50 feet from -die point of entry into
the soil, "soil defense" mechanisms such as antibiotic activity and
competition will begin to act and cause increased die-off resulting
in a retreat of the bacterial front (Romero, 1970).
It should be noted that pathogens removed in the upper layers
of soil will be concentrated near the soil area where crops will
be grown. Pathogens could directly pass to crops such as lettuce
or beets from soil contamination or be carried to above ground
crops by flies or dust. The dust-borne epidemic of Salmonellosis
in Israel indicates that this is not outside the realm of possibility.
Fractures or channels in underlying geological formations will also
affect pathogen movement in soil. Vogt (1961) reported a waterborne
epidemic of infectious hepatitis which followed limestone fractures
from a septic tank to individual wells considerable distances
away from the source. Laboratory and field studies cannot be v
completely relied upon as to distance of travel since small quanti-
ties of pathogens may escape removal, particularly in fractured
geological formations. Epidemiological evidence of bacteria and
viruses travelling considerable distances to water supplies is dis-
comfiting, particularly since levels of pathogens sufficient to
result in infection may not be detectable in dilute solution with
presently available techniques.
StNMARY AND CONCLUSIONS
This paper has present a good deal of data couched in terms of
possible or potential hazards. How real are the hazards in terms of
the realities of actual cases of disease resulting from wastewater
application on soil? The epidemiological evidence suggests that few
disease incidences have been related to this practice. Krone (1968)
reviewed an incident involving sewage contamination of fruits and
235
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vegetables on a farm in 1919 which resulted in 8 cases of typhoid
fever. A possible 2500 cases of gastroenteritis due to Shigella
an^ Salmonella occurred in California in 1965 under highly unusual
circumstances (Heukelekian and Albanese, 1956). Wastewater applied
to a pasture traveled overland to a gopher hole and then into a
poorly protected municipal water supply well. The chances of such
an event repeating itself are highly unlikely. The literature is
quite unusual in the paucity of information available on irrigation-
caused epidemics. This may well reflect an absence of a problem
despite other evidence indicating that significant quantities of
pathogens are placed on soil by this practice. On the other hand,
it may only reflect prejudices which regard only significant out-
breaks of disease to be worthy of investigation. Epidemiological
tools are insensitive for isolated or sporadic small scale out-
breaks. Resulting sporadic infection may not result in actual
clinical symptoms but could create foci for disease dissemination
by other modes of transmission. While the potential for low-level
transmission of disease is speculative, it is a possibility worthy of
investigation. Until such time as the danger of sporadic disease
transmission can be ruled out, a high degree of treatment of
applied wastewater including free residual chlorination would seem
to be indicated. Geological conditions underlying soil to which
wastewater is applied should not contain channels or fractures
which may permit pathogens to move long distances. More than one
month, preferably more than two months, should be allowed between the
last application of wastewater and harvesting edible crops. In this
way both actual hazards of disease transmission and public appre-
hension may be reduced.
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241
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VEGETATION RESPONSES TO IRRIGATION WITH TREATED
MUNICIPAL WASTEWATER
William E. Sopper and Louis T. Kardos
School of Forest Resources and Department of Agronomy
The Pennsylvania State University
Many water pollution problems have been created and worsened
by the disposal of treated municipal wastewater into streams, lakes,
and oceans. There are currently about 16,000 sewage treatment plants
in the United States discharging more than 26 billion gallons of
effluent daily. This is only a beginning. As environmental quality
pressures mount more plants will have to be built to meet new strin-
gent water quality standards. This move from dispersed simple
wastewater treatment by many individual septic tanks to collection
and concentration of wastewater for treatment at a single plant
provides only a partial solution to water pollution problems.
Advanced secondary treatment eliminates the health hazard associated
with untreated wastes and most of the organic matter is decomposed
into its inorganic components. However, it is the concentrated
discharge of these mineral-enriched effluents into a balanced
aquatic environment which causes ecological chaos and disrupts the
natural recycling process.
CHEMICAL COMPOSITION OF MUNICIPAL
SEWAGE EFFLUENT
The chemical composition of municipal effluent is illustrated
in Table 1 based upon samples collected during 1971 from the Univer-
sity treatment plant. This plant services both the University and
the borough of State College. Treatment consists of both primary
and secondary treatment. Secondary treatment includes standard and
high-rate trickling filters and a modified activated sludge process
followed by final settling. Weekly variations in concentration of
constituents are shown by the range between maximum and minimum
values. The total amount of each constituent applied per acre per
year at the 2-inch per week rate is also given in Table 1.
The fertilizer value of these wastewaters is readily evident.
The amount of N-P-K applied through spray irrigation of effluent in
forested areas at the rate of 2 inches per week during the past 9
years is given in Table 2. The average annual applications provided
commercial fertilizer constituents equivalent to approximately 208
pounds of nitrogen, 200 pounds of phosphate (P20s), and 227 pounds
of potash (K20). This would be equal to applying about 2000 Ibs of
a 10-10-11 fertilizer annually.
242
-------
Table 1. Chemical Composition of Sewage Effluent Applied During 1971
Range Total Amount
Constituent Minimum Maximum Average Applied.!/
mg/1 mg/1 mg/1 Ibs/acre
PH r\ 1
MBAS^-7
Nitrate-N
Organic -N
Mty-N
Phosphorus
Calcium
Magnesium
Sodium
Boron
Manganese
7.4
0.03
2.6
0.0
0.0
0.250
23.1
9.1
18.8
0.14
0.01
8.9
0.88
17.5
7-0
5.0
4.750
27.8
15.1
35.9
0.27
0.04
8.1
0.37
8.6
2.4
0.9
2.651
25.2
12.9
28.1
0.21
0.02
—
5
128
36
13
39
375
192
419
3
0.2
— Amount applied on areas which received 2 inches of effluent per
week.
2/
— Methylene blue active substance (detergent residue) values are
for 1970, constituent not included in analyses in 1971.
243
-------
Table 2. Amount of N-P-K Applied Annually in Forested Areas Through
Spray Irrigation of Effluent
Total
Year Effluent N P K
Applied!/
inches Ibs/a Ibs/a Ibs/a
1963^
1964
1965
1966
1967
1968
1969
1970
1971
46
66
62
62
56
62
56
54
58
119
256
139
170
157
351
275
217
184
54
116
122
129
98
119
66
43
40
127
234
199
238
176
261
175
120
174
Mean 58 208 87 189
— Applied 2 inches per week.
2/
— First year irrigation started June 18, 1963 and therefore values
only represent a partial year.
244
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THE PENN STATE WASTEWATER RENOVATION
AND CONSERVATION PROJECT
Treated municipal sewage effluent has been spray irrigated on
cropland and in forest stands for a 10-year (1963-72) period. Efflu-
ent has been applied in various amounts ranging from 1 inch per week
to 6 inches per week and over various lengths of time ranging from
as little as 16 weeks during the growing season on cropland to the
entire 52 weeks in forests. Rates of application have varied from
0.25 to 0.64 inch per hour.
Types of crops irrigated with effluent were wheat, oats, corn,
alfalfa, red clover, and reed canarygrass. Forested areas irri-
gated consisted of a mixed hardwood forest, a red pine plantation
(Pinus resinosa Ait.), and a sparse white spruce (Picea glauca
Muencn" Vo's's.) plantation established on an abandoned old field.
Detailed descriptions of these areas have been previously reported
by Sopper (1968, 1971).
CROP RESPONSES
Yields
The sequence of annual crop rotation is given in Table 3.
During the initial years of the project a variety of crops were
tested. Since 1968 the two primary crops used have been silage
corn and reed canarygrass. As will be discussed later these two
crops appear to be the most efficient in terms of the utilization
of the crop to remove nutrients applied to a site in the effluent.
Average crop yields obtained from 1963 to 1970 are given in
Table 4. During this 8-year period the crop areas irrigated with
2 inches of effluent weekly received a total of 392 inches of waste-
water equivalent to applying 10,000 pounds of a 13-6-15 commercial
fertilizer. The control area was fertilized with commercial ferti-
lizer ranging from 200 pounds of 0-20-20 per acre for oats to 1000
pounds of 10-10-10 on corn. Effluent irrigation at 2 inches per
week resulted in annual yield increases ranging from -8 to 346
percent for corn grain, 5 to 130 percent for corn silage, 85 to 191
percent for red clover, and 79 to 139 percent for alfalfa. Yield
differences between the effluent-irrigated and control plots were
greatly influenced by growing season precipitation. During the
years, 1963 to 1966, when growing season (May 1 - September 30)
precipitation was 5 to 8 inches below normal, yields on the irri-
gated areas were significantly greater than on the control areas,
but usually differences between the 1-inch and 2-inch per week
applications were not significantly different. In 1967 and 1969,
when growing season precipitation was slightly above normal, yield
differences were not significant. In 1970, with growing season
245
-------
TABLE 3. Annual Crop Sequence
t-o
Area
1
2
3
4
5
6
7
1963
corn—'
wheat
red clover
wheat
corn
red clover
alfalfa
1964
oats
red clover
corn
red clover
oats
corn
corn
1965
alfalfa
corn
oats
corn
alfalfa
oats
oats
1966
alfalfa
corn
alfalfa
corn
alfalfa
alfalfa
alfalfa
1967
alfalfa
corn
alfalfa
corn
alfalfa
alfalfa
alfalfa
1968-72
corn
corn
corn
corn
corn
corn
corn
— Includes 1-inch and 2-inch per week irrigated plots and a control plot.
-------
I/
TABLE 4. Average Annual Crop Yields at Various Levels of Application of Sewage Effluent-'
1963
Wheat (bushels/acre)
Com (bushels/acre)
Alfalfa (tons/acre)
Red clover (tons/acre)
1964
Red clover (tons/acre)
Corn (bushels/acre)
Corn stover (tons/acre)
Oats (bushels/acre)
1965
Alfalfa (tons/acre)
Corn (bushels/acre)
Corn silage (tons/acre)
Oats grain (bushels/acre)
Oats straw (tons/acre)
Reed canarygrass (tons/acre)
1966
Alfalfa (tons/acre)
Corn (bushels/acre)
Corn silage (tons/acre)
Reed canarygrass (tons/acre)
0 inch/week
48
75
2.18
2.48
1.76
81
3.83
82
2.27
63
3.11
45
1.62
--
1.95
33
2.47
1 inch/week
45
105
3.73
4.90
5.30
121
7.29
124
4.67
114
3.93
80
2.90
--
3.86
98
4.45
2 inches/week
54
106
5.12
4.59
5.12
116
8.48
97
5.42
111
4.32
73
2.63
6.13
4.38
115
5.68
4.32
-------
TABLE 4. Continued
to
•£>
00
1967
Corn Pa. 444
19- inch row (bushels/acre)
38 -inch row (bushels/acre)
Corn Pa. 602-A
19 -inch row (bushels/acre)
Corn silage Pa. 602-A
19-inch row (tons/acre)
Alfalfa (tons/acre)
Reed canarygrass (tons/acre)
1968
Reed canarygrass (tons/acre)
1969
Corn Silage
Pa. 602-A (tons/acre)
Pa. 890 -S (tons/acre)
Reed canarygrass (tons/acre)
1970
Corn Silage
Pa. 602-A (tons/acre)
Pa. 890- S (tons/acre)
Reed canarygrass (tons/acre)
0 inch/week
98
92
122
4.43
2.43
--
5.19
6.90
--
4.35
5.20
«•* •*
1 inch/week
101
83
121
4.47
3.77
--
5.77
6.66
--
6.44
4.97
— —
2 inches/week
122
84
114
4.67
4.36
7.03
5.09
5.49
7.27
5.18
6.00
5.58
5.53
— Part of table obtained from Kardos (1971); yields in tons per acre reported on a dry weight
basis; corn grain yields are expressed on the basis of 56 pounds per bushel at 15.5 percent
moisture content.
-------
precipitation again below normal (1.55 inches), yield differences
between the control and irrigated areas were again significant
but the two levels of irrigation were not.
Nutrient Composition
tinder the "living filter" concept the higher plants growing
on the soil are an integral part of the system and assist the
microbiological and physio-chemical activities occurring within the
soil to renovate the sewage effluent through removal and utiliza-
tion^ of the nutrients applied. The average nutrient composition of
the corn silage and reed canarygrass harvested during 1970 is given
in Tables 5 and 6. The crops harvested from the 2-inch per week
irrigated areas are usually higher in nitrogen and phosphorus than
the control crops. As indicated in Table 5 the differences are not
large. This is partially due to the fact that the control area
receives a normal application of commercial fertilizer each year.
For instance, the silage corn control area has received 600 to 1000
pounds of a 10-10-10 fertilizer per acre annually.
Nutrients Removed by Crop Harvest
The contribution of the higher plants as renovators of the
wastewater is readily evident from Tables 7 and 8 when the quanti-
ties of nutrients, expressed in pounds per acre, removed in the
1970 crop harvest are given. These data indicate that the vegeta-
tive cover can contribute substantially to the durability of a
"living filter" system particularly where a crop is harvested and
utilized. At the 2-inch-per-week level of effluent irrigation the
two com varieties removed 148 and 160 pounds of nitrogen and 35
and 43 pounds of phosphorus. Reed canarygrass, which is a peren-
nial grass, was even more efficient in that it removed 408 pounds
of nitrogen and 56 pounds of phosphorus. The difference is
primarily due to the fact that the grass is already established
and actively growing in early spring even before the corn is plant-
ed.
The amounts of nutrients removed annually vary with the amount
of wastewater applied, amount of rainfall, length of the growing
season, and the number of cuttings of the reed canarygrass.
The efficiency of crops as renovating agents can be assessed
by computing a "removal efficiency" expressed as the ratio of the
weight of the nutrient removed in the harvested crop to the weight
of the same nutrient applied in the wastewater. Renovation
249
-------
TABLE 5. Average Nutrient Composition of Two Varieties of Corn Silage Receiving Various Levels
of Effluent During 1970
tn
o
Nutrient
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
Variety and amount of effluent applied per week
Corn Silage, Pa. 890 -S Corn Silage, Pa. 6 02 -A
012 012
%
1.18
0.22
1.00
0.39
0.16
0.21
ug/g
14
6
%
1.24
0.29
0.98
0.28
0.22
0.36
vg/g
171
8
%
1.32
0.31
1.02
0.25
0.22
0.34
yg/g
176
8
%
1.34
0.21
1.04
0.48
0.16
0.19
Pg/g
12
7
%
1.36
0.28
1.10
0.32
0.21
0.36
yg/g
167
7
%
1.34
0.35
1.07
0.23
0.19
0.39
yg/g
201
7
-------
TABLE 6. Average Nutrient Composition of Reed Canarygrass
Irrigated With 2 Inches of Effluent During 1970
Nutrient
Nitrogen
Phosphorus
Potass ium
Calcium
Magnesium
Chloride
Sodium
Boron
First
Cut
%
4.06
0.44
2.50
0.39
0.36
1.50
vg/g
331
8
Second
Cut
%
3.44
0.51
2.26
0.40
0.40
1.64
^g/g
329
8
Third
Cut
%
3.34
0.64
1.63
0.42
0.32
0.94.
vg/g
228
8
Weighted, /
Average—'
%
3.69
0.50
2.23
0.40
0.36
1.57
vg/g
309
8
— Based on the average yield for each cutting.
251
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TABLE 7. Quantities of Nutrients Removed by Reed Canary-grass
Irrigated With 2 Inches of Effluent During 1970
Nutrient
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
First
Cut
196.5
21.3
121.0
18.9
17.4
72.6
1.6
0.04
Second
Cut
pounds per acre
134.2
19.9
88.1
15.6
15.6
64.0
1.3
0.03
Third
Cut
77.5
14.8
37.8
9.7
7.4
21.8
0.5
0.02
Total
408.2
56.0
246.9
44.2
40.4
158.4
3.4
0.09
252
-------
TABLE 8. Quantities of Nutrients Removed By Two Varieties of Corn Silage Receiving Various Levels
of Effluent During 1970
IN)
Cn
Nutrient
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
Variety and amount of effluent applied per week
Corn Silage, Pa. 890-S Corn Silage, Pa. 602-A
01 2 0 1 2
129.4
24.3
105.6
41.2
16.3
21.6
0.14
0.06
pounds per acre
126.1
29.4
95.7
27.4
21.5
35.2
1.66
0.08
148.4
34.7
113.1
28.5
23.7
37.2
1.90
0.08
117.5
18.6
91.6
39.9
14.1
17.1
0.11
0.06
pounds per acre
174.4
35.6
137.1
41.4
27.6
44.6
2.13
0.10
160.6
42.8
129.3
27.0
23.2
46.4
2.39
0.09
-------
efficiencies for the silage corn and the reed canarygrass crops
harvested in 1970 are given in Table 9. At the 1-inch-per-week
level of application of wastewater, the two varieties of com
silage removed nutrients equivalent to 242 and 334 percent of the
total applied nitrogen, 190 and 230 percent of the applied phos-
phorus, and 195 and 280 percent of the applied potassium. At the
2-inch-per-week level, both varieties of corn silage removed more
than 100 percent of the applied nitrogen, phosphorus, and potassium.
During 1970 the reed canarygrass removed only 75 percent of
the applied nitrogen, and 3 percent of the applied phosphorus.
These are not typical annual values for the 1965-70 period. During
the period 1965 to 1969 only sewage effluent was applied. In 1970
irrigation applications included a combination of sewage effluent
and injected liquid digested sludge. During the period 1965-69,
1581 pounds of nitrogen were applied and the harvested reed canary-
grass removed 1663 pounds, equivalent to a 105 percent renovation
efficiency. In 1970, an additional 546 pounds of nitrogen were
applied making the total 2127 pounds applied in 536 inches of
wastewater. Since only 408 pounds were removed by crop harvesting
the overall 6-year period renovation efficiency was lowered to
97.5%.
During the same period, 797 pounds of phosphorus were applied
in the wastewater and 279 pounds removed in crop harvesting
resulting in an overall renovation efficiency of 35 percent.
Annual renovation efficiencies have varied from 24 to 63 percent
for reed canarygrass irrigated at the 2-inch-per-week level. For
corn silage it has varied from 39 to 230 percent for the 1-inch-per-
week level and from 21 to 143 percent for the 2-inch-per-week
level. Hence, it is obvious that some process other than utiliza-
tion by the vegetative cover must be used to assure the removal of
this key eutrophic nutrient. This additional renovation and removal
of phosphorus is usually accomplished by way of the large fixing
capacity of most agricultural soils for phosphorus. At the Penn
State sites, the Hublersburg soils, which range in texture from a
silt loam to a silty clay loam, have persistently and effectively
removed the phosphorus.
The fate of phosphorus and nitrogen on the reed canarygrass
area irrigated with municipal wastewater at 2-inches-per-week since
1965 are shown in Table 10. After 6 years of applying chlorinated
effluent, 797 pounds of phosphorus and 2127 pounds of nitrogen had
been applied to each acre in 536 inches of effluent. Harvested
crops removed 270 pounds of phosphorus, the equivalent of 35 percent
of the amount added. Since the concentration of phosphorus in the
percolate at the four foot soil depth was only 0.05 mg/1 and was no
greater than that in an unirrigated adjacent forest area, the net
percolation losses of phosphorus from the wastewater treated areas
254
-------
tn
tn
TABLE 9. Renovation Efficiency of the Silage Corn and Reed Canarygrass Crops Harvested in 1970
Nutrient
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Chloride
Sodium
Boron
Corn Silage,
1
%
242
190
195
25
41
20
1
8
Variety
Pa. 890-S
2
1
134
116
114
16
28
11
1
4
and amount of
Corn Silage,
1
%
334
230
280
38
53
26
2
10
effluent applied
Pa. 602 -A Reed
2
%
145
143
130
15
27
14
1
4
canarygrass
2
%
75
63
117
9
19
20
1
2
-------
TABLE 10. Phosphorus and Nitrogen Balances for Reed Canarygrass Irrigated with Effluent at Two
Inches Per Week During the Period 1965 to 1970
Period
1965-70
Amount Applied
Wastewater Nutrient
inches Ibs/acre
536 797 (P)
2127 (N)
Removed
By crop By leaching
Ibs/acre
279 (P)
2073 (N)
Ibs/acre
6.4 (P)
452 (N)
Retained
by soil
Ibs/acre
512 CP)
-398 (N)
tv)
tn
-------
were assumed to be proportional only to the excess percolation
induced by the added wastewater. Further, since precipitation
always exceeds potential evapotranspiration 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 6-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
removed 99.2 percent of the added phosphorus.
Nitrogen removals by the soil and crop system have also been
equally efficient. Over the 6 year period 2127 pounds of nitrogen
were added to each acre. Protein removed in the harvested reed
canarygrass was equivalent to 2073 pounds of nitrogen per acre.
Kjeldahl nitrogen content of the upper foot of soil was approxi-
mately 5000 pounds per acre. Average concentration of nitrate-N in
the percolate at the four foot soil depth during the 6-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 assumptions used above,
the excess percolate from the 536 inches of wastewater applied per
acre would have carried a total of 452 pounds of nitrogen into the
groundwater. This quantity is 398 pounds in excess of the 54 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 97.5
percent of the added nitrogen.
FOREST RESPONSES
Red Pine
Experimental plots were established in a red pine plantation
in 1963. These plots have been irrigated with sewage effluent
during the past 10 years at rates of 1 inch and 2 inches per week
during the growing season (April to November). The plantation was
established in 1939 with the trees planted at a spacing of 8 by 8
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 on
sample trees selected at random on each irrigated plot and on
adjacent control areas. Average annual height growth for the period
1963 to 1970 is given in Table 11. Irrigation with sewage effluent
at both rates produced slight increases in height growth during the
first 2 years. This slight increase in height growth has been
257
-------
maintained on the plot receiving 1 inch per week. However, on the
plot receiving 2 inches per week, height growth continually de-
creased up to 1968 when high winds during a wet snowfall completely
felled every tree on the plot.
TABLE 11. Average Annual Terminal Height Growth of Red Pine
Irrigated with Sewage Effluent
Average annual
Treatment height growth
feet
Irrigated - 1 inch per week (1963-70) 1.8
Control 1.4
Irrigated - 2 inches per week (1963-68) 1.6
Control 1.7
Diameter growth was computed from annual circumference measure-
ments with dendrometer bands. In addition increment cores were
taken in 1972 from sample trees in all areas. The actual measure-
ments of average radius growth taken from the increment cores
indicate that the previous diameter growth data reported (Sopper,
1971) which was based upon dendrometer band measurements of tree
circumferences was incorrect. Average annual diameter growth based
on increment core measurements is given in Table 12. Irrigation at
the 1-inch-per-week level increased the average annual diameter
growth (1963-68). In addition, during the sixth year (1968) of
irrigation the needles of the pines being irrigated at the higher
rate began to turn yellow. Boron toxicity was suspected since other
investigators (Stone and Baird, 1956) have previously reported that
applications of 1.1 pounds of boron per acre were sufficient to
induce toxicity symptoms. Approximately 4 pounds of boron per acre
are applied annually in the sewage effluent. However, foliar
analyses indicated that there was no significant difference between
boron concentrations of the needles of trees on the irrigated (33
micrograms per gram) and control (23 micrograms per gram) trees.
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 3 to 8 feet in height. One plot has been irrigated with
sewage effluent during the past 10 years at the rate of 2 inches per
258
-------
TABLE 12. Average Annual Diameter Growth of Red Pine Irrigated
With Sewage Effluent
Average annual
Treatment diameter growth
inches
Irrigated - 1 inch per week (1963-72) 0.17
Control 0.06
Irrigated - 2 inches per week (1963-68) 0.06
Control 0.07
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 was measured in August 1972. Average
height of the trees on the irrigated plot was 20 feet and ranged
from 12 to 25 feet. The average height of the trees on the control
plot was 9 feet and ranged from 8 to 15 feet. Over the 10-year
period average annual height growth was 18 inches on the irrigated
areas and 5 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,
on the control plot it was 1.1 inches. Measurements taken from
increment cores indicated 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.
Old Field Herbaceous Vegetation
The predominant ground cover on the old field area of the
spruce plantation was poverty grass (Danthonia spicata. Beauv.),
goldenrod (Solidago spp. Ait.), and dewberry (Rubus Flagellaris
Willd.).
Permanent transect plots were established in 1964 and measured
annually to determine the effects of sewage effluent irrigation on
the herbaceous ground cover in terms of species composition, height
growth, dry matter production and percentage areal cover.
Average annual dry matter production during the 10-year period
was 5457 pounds per acre on the irrigated plot and 1810 pounds per
acre on the control plot (Table 13). This represents an average
259
-------
annual increase of 201 percent. Annual increases ranged from 100
to 350 percent.
to 350 percent
TABLE 13. Average Annual Dry Matter Production of Herbaceous
Vegetation in the Old Field Area
Irrigated Control
Year plot plot
Ibs/acre Ibs/acre
1963 3381 1470
1964 7607 1763
1965 5672 1675
1966 6417 1435
1967 4075 2010
1968 6044 1550
1969 5909 2015
1970 5505 1605
1971
1972 5007 2770
Mean 5457 1810
Species composition of the ground vegetation has changed con-
siderably during the 10 years as a result of sewage effluent
irrigation. Several species which were predominant prior to waste-
water irrigation have been drastically reduced in number or have
disappeared completely. For instance, 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 pilosus) which had 122,970
steins per acre in 1963 was not present on the site in 1972. The
predominant species on the irrigated plot was clearweed (Pilea
gumila L.) which covered more than 75 percent of the plot with
approximately 19 million stems per acre. This species is typical
of shaded moist sites.
Species composition changes are illustrated in Table 14 based
on measurements made in 1972. The control plot is representative
of preirrigation vegetation conditions.
The average height of the tallest plant species on the irrigated
plot was 5.3 feet in comparison to 1.8 feet on the control plot.
While the irrigated plot had a complete dense vegetative cover ap-
proximately 10 percent of the control was barren of vegetation.
260
-------
TABLE 14. Predominate Herbaceous Vegetation Species on the Irrigated and Control Plots of
White Spruce Area in 1972
ISJ
Species
Goldenrod (Solidago juncea)
Aster (Aster spp.)
Dewberry (Rubus flagellaris)
Strawberry (Fragaria vesca)
Poverty grass (Danthonia spicata)
Everlasting (Antennaria spicata)
Goldenrod (S. .rugosa, S. g r aminif ol ia ,
S. juncea])
Milkweed (Asclepias^ rubra)
Indian Hemp (Apocynum cannabinum)
Night shade (Solanum dulcamara)
Clearweed (Pilea pumila)
Irrigated Plot
Percent
cover
%
1
0
0
5
0
0
5
5
5
10
75
Average
height
feet
2.8
--
--
0.9
--
--
5.3
5.1
3.3
2.3
1.5
Control Plot
Percent
cover
%
5
5
40
10
20
5
0
0
0
0
0
Average
height
feet
1.8
1.1
0.8
0.5
0.3
0.1
--
--
--
--
-------
Coniferous Tree Seedling Growth Responses
In 1965 eight coniferous tree species were planted in an old-
field area to determine which species might be best suited for
sites to be used as disposal areas for sewage effluent. One- and
two-year-old seedlings of European larch (Larix decidua), Japanese
larch (Larix leptolepis), white pine (Firms sJ^rdbusT, red pine,
white spruce, pitch pine (Pinus rigida)Vlfcstri'an' pine (Pinus
nigra), and Norway spruce (Picea abies) were planted in a random-
izecTblock design with three blocks "irrigated with 2 inches of
sewage effluent per week and three blocks maintained as a control.
Each block contained 10 trees of each species or a total of 80
trees per block. Average first-year survival on the irrigated
plots was 88 percent and on the control plots, 52 percent. At the
termination of the study in 1970 survival percentage on the irri-
gated plots was still 88 percent, whereas the survival percentage
on the control plots had decreased to 41 percent. The total
height growth of surviving tree seedlings as of 1970 is given in
Table 15.
TABLE 15. Total Height Growth of Surviving Tree Seedlings During
the Period 1965 to 1970
Irrigated Plots
Control Plots
Species
Survival Height Survival Height
European larch
Japanese larch
White pine
Red pine
White spruce
Pitch pine
Austrian pine
Norway spruce
%
23
17
70
40
30
3
13
47
feet
8.7
8.4
6.3
5.4
4.3
3.8
3.6
3.6
%
0
0
17
20
3
3
13
7
feet
--
--
2.6
2.0
2.8
1.4
2.1
1.6
Results indicate that European and Japanese larch and White
pine had the greatest growth response to sewage effluent irrigation.
Hardwood Species Growth Responses
Mixed hardwood forests, consisting primarily of oak species,
have been irrigated with sewage effluent at rates ranging from 1 inch
to 4 inches per week and for periods ranging from the growing season
262
-------
(28 weeks) to the entire year (52 weeks). Principal species are
white oak (Quercus alba L.), chestnut oak (Q. prinus L.), black oak
(Q. velutina L.), red oak (6. rubra L.), scarlet oak (Q. cpccinea
Muench.), red maple (Acer rubrun), and hickory (Carya spp.).
Average annual diameter growth in various treatment areas from
increment core measurements in 1972 is given in Table 16. One inch
per week applications produced only slight increases in diameter
growth on the older trees (age); however, the 2- and 4-inch-per-week
levels in a younger stand resulted in 69 and 40 percent increases,
respectively. These values pertain primarily to the oak species.
Some of the other hardwood species present on the plots have respond-
ed to a greater extent. For instance, increment core measurements
made on young red maple and sugar maple (A. saccharum), indicate
that the average annual diameter growth during the past 10 years has
been 0.43 inch on the trees irrigated with 1 inch of effluent per
week in comparison to 0.10 inch on control trees, a 330 percent
increase in average annual diameter growth. Similarly, increment
core measurements made on aspen (Populus^ tremuloides) irrigated with
2 inches of effluent weekly during the growing^seasbn indicated 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 in comparison to 3.1 inches on the control areas.
TABLE 16. Average Annual Diameter Growth in Hardwood Forests
Irrigated with Sewage Effluent
Weekly irrigation Average diameter growth
amount Control
Irrigated
inches inch inch
li/ 0.16 0.18
2^ 0.13 0.22
4^ 0.15 0.21
I/ Irrigated with 1 inch of sewage effluent weekly during growing
season from 1963 to 1972.
- Irrigated with 2 inches of sewage effluent weekly during the
entire year from 1965 to 1972.
— Irrigated with 4 inches of sewage effluent weekly during the
growing season only from 1964 to 1967; during the dormant
season only from 1968 to 1971; and with 2 inches of effluent
weekly during the growing season in 1972.
263
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Tree Seedling Reproduction
Mil-acre plots were established in 1964 in the hardwood forest
irrigated with 1 inch of effluent weekly. These plots have been
measured annually to deteimine the effect of wastewater irrigation
on tree seedling reproduction and growth of herbaceous vegetation.
Measurements made in 1972 after 10 years of sewage effluent irriga-
tion indicate a drastic reduction in the number of tree seedlings
present in the irrigated area. The initial survey in 1964 indi-
cated 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 irrigation) there were 14,500 tree seedlings per
acre present in the irrigated area and only 1,830 in 1972. No
conclusive evidence is yet available to explain these results.
These results may be partially due to the fact that effluent irri-
gation stimulates leaf growth which produces a more dense canopy
and reduces light intensity at the forest floor. Average light
intensity under the canopy in the irrigated area was less than 50
percent of that under the control plot canopy.
A similar reduction was also found in the number of herbaceous
plants in the irrigated 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.
Mortality
In 1972 a survey was made in the irrigated and control forested
areas at the Gamelands site to determine the effect of 8 years of
sewage effluent irrigation on mortality. Mortality was defined as
all standing dead trees. The irrigated plot received 4 inches of
sewage effluent weekly during the growing season only from 1964 to
1967; during the dormant season only from 1968 to 1971; and 2 inches
of effluent weekly during the growing season in 1972. The results
of the survey are given in Table 17. Results indicated that there
was no difference in mortality between the irrigated and control
areas. There was, however, a large difference in the number of
living trees per acre, particularly, in the 2-inch diameter class.
Unirrigated forest areas averaged 290 trees per acre in the 2-inch
diameter class compared to only 70 trees per acre in the irrigated
forest areas.
Although many of these young saplings are lost through natural
suppression, a considerable number are lost in the irrigated areas
through ice breakage during winter irrigation. The 1972 survey
results indicated that approximately 52 stems per acre showed
visible ice damage in the irrigated areas in comparison to 7.5
264
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TABLE 17. Population and Mortality in Forested Stands in Control
Plots and Plots Irrigated with Sewage Effluent for
Eight Years
Diameter
class
inches
2
4
6
8
10
12
14
16
Living trees
Irrigated
steins per
70
100
40
60
40
30
2
5
Control
acre
290
110
80
80
50
25
7
Mortality
Irrigated
stems per
55
27
20
2.5
__
--
—
Control
acre
42
32
5
2.5
5
--
--
—
Total
347
642
104.5
106.5
stems per acre in the control areas. Seventy-five percent of these
trees were in the 2-inch diameter class and the remainder in the
4-inch diameter class. The species most susceptible to ice damage
was red maple. A reasonable amount of ice damage must be expected
if disposal systems are to operate throughout the year. In northern
latitudes where the temperatures drop below freezing, the system
must rely more on the adsorptive capacity of the soil and less on
the microbial activity and vegetation for renovation of the waste-
water. During the winter period, forested areas provide better
infiltration conditions. They also provide larger phosphorus-
adsorptive capacity due to the acid conditions associated with
forest soils. Ice damage can be minimized through the proper design
of the spray-irrigation system and the use of low-trajectory rota-
ting sprinklers (Parizek et al, 1967; Myers, 1973).
A comparison of the results of the 1972 survey made in the
effluent-irrigated forest areas with the results of forest surveys
(Melton, 1972) of several mixed hardwood stands on a variety of
sites in central Pennsylvania indicate that 10 years of effluent
irrigation have produced no great differences. The average number
of living trees, 5 inches in diameter and greater, in the e f fluent-
irrigated forests was 177 stems per acre in comparison to an
average of 155 stems per acre in several natural mixed hardwood
stands. Mortality of trees, 5 inches in diameter and greater, in
the effluent-irrigated forests was 22.5 stems per acre in compari-
son to an average 21 stems per acre in several natural mixed hard-
wood stands.
265
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Annual Nutrient Balance
Foliar samples were collected annually up to 1967 from the
hardwoods, red pine, white spruce, and herbaceous vegetation to
determine the extent of utilization of the nutrient elements
applied in the sewage effluent. The nutrient element contents of
the vegetation foliage based on samples collected in August 1967
are given in Table 18. Average concentrations of N, B, P, mg, Cu,
and Na were almost consistently higher on the irrigated plots than
on the control plots. Conversely, average concentrations of K,
Mn, Al, and Zn were generally lower on the irrigated plots. Con-
centrations of Ca and Fe were highly variable and indicated no
distinct trends. It is therefore obvious that the forest vegeta-
tion 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 nutrients 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.
Tree leaves are by far the largest single source of forest soil
organic matter, and their annual contribution of mineral elements
to the soil greatly exceeds that of all other tree parts combined.
A comparison between the annual uptake of nutrients by an
agronomic crop (silage com) and a hardwood forest is given in
Table 19. It is obvious that trees are not as efficient renovat-
ing agents as agronomic crops. Whereas harvesting a corn silage
crop removes 145 percent of the nitrogen applied in the sewage
effluent, the trees only remove 39 percent most of which is
returned to the soil by leaf fall. Similarly only 19 percent of
the phosphorus applied in the sewage effluent is taken up by trees
in comparison to 143 percent by the corn silage crop.
Problems of Forest Irrigation
Three potential problems that may be encountered with effluent
irrigation in forested areas are (1) ice damage, (2) windthrow,
and (3) bark damage by sprinkler spray. The ice breakage problem
has already been discussed. Bark damage by sprinkler spray can be
avoided if sprinkler nozzle pressures are operated at or less than
55 p.s.i. Nozzle pressures for the solid set system used in the
forests on the Penn State project are approximately 50 p.s.i.
Little tree damage has been observed even on small trees within a
2-foot radius of the sprinkler head.
266
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TABLE 18. Average Chemical Content of the Tree Foliage and Herbaceous Vegetation from Samples
Collected in 1967
Plot
Hardwood 1-inch
Irrigated
Control
Hardwood 2 -inch
Irrigated
Control
Red pine 1-inch
Irrigated
Control
Red pine 2-inch
Irrigated
Control
White spruce 2 -inch
Irrigated
Control
Old- field
Vegetation 2 -'inch
Irrigated
Control
N
2.45
2.20
2.97
2.20
1.62
1.15
2.17
1.33
2.19
1.48
3.28
1.30
P
Percent
0.22
0.18
0.29
0.18
0.17
0.16
0.13
0.15
0.29
0.19
0.45
0.16
K
Ca
Mg
Mn
Fe
Cu
B
Al
Zn Na
of dry weight vg/g
0.86
0.87
0.93
1.13
0.58
0.53
0.52
0.61
0.67
0.71
2.34
1.19
1.00
0.99
0.77
1.01
0.19
0.29
0.26
0.24
0.84
0.93
1.23
1.09
0.14
0.08
0.19
0.09
0.09
0.09
0.10
0.08
0.12
0.13
0.44
0.13
1500
1845
1830
2725
942
1103
947
925
517
834
235
642
88
80
81
83
41
53
58
54
90
57
379
400
8
7
7
8
4
4
4
3
6
5
19
13
81
49
117
65
28
19
33
23
38
26
39
35
68
66
50
80
142
496
97
394
87
100
825
958
26 15
27 16
33 13
25 16
33 44
45 8
32 114
40 11
35 117
95 10
94 473
95 28
-------
TABLE 19. Annual Uptake of Nutrients by a Silage Corn Crop and a
Hardwood Forest Irrigated with 2 Inches of Effluent
Weekly During 1970
Nutrient
N
P
K
Ca
Mg
Corn Silage
Pa. 602 -A
Ibs/acre
161
42
129
27
23
Renovation
efficiency!/
1
145
143
130
15
27
Hardwood
forest^'
Ibs/acre
84
8
26
22
5
Renovation
efficiency
1
39
19
22
9
4
— Percentage of the element applied in the sewage effluent that
is utilized and removed by the vegetation.
2 /
— Calculations based on an average annual leaf fall of 2825
pounds of dry matter per acre (Lutz and Chandler, 1946).
Windthrow of individual trees and large numbers of trees (the
1-acre red pine plot irrigated with 2 inches of effluent weekly) has
been the greatest problem. Weekly irrigation of sewage effluent at
rates of 1 and 2 inches per week keep the soil moisture status near
field capacity and hence encourages the development of shallow tree
root systems. In November of 1968, following a weekly application
of 2 inches of sewage effluent, a heavy snowfall accompanied by
strong winds resulted in the complete blow down of the one-acre plot.
Since then several individual trees have also been windthrown in
the mixed hardwood forests. Most of these trees have been adjacent
to natural forest openings, agricultural fields, or power line
rights-of-way. It appears that this problem could be minimized if
an unirrigated buffer zone 50 to 100 feet wide were left on the
windward side of any irrigated forest area. This buffer zone would
provide a wind break against prevailing winds.
CONCLUSIONS
Sewage effluent irrigation during the past 10 years on cropland
and in forestland has, for the most part, produced beneficial vege-
tation responses. Crop yields and tree growth were significantly
increased. In addition the value of the vegetation as a renovating
agent has been demonstrated to be a vital part of the system. For
year-around operations a combination of cropland and forestland will
provide the greatest flexibility in operating a system using the
"living filter" concept.
268
-------
ACKNOWLEDGEMENT
Research reported here is part of the program of the Waste
Water Renovation and Conservation Project.of the Institute for
Research on Land and Water Resources, and Hatch Projects No. 1481
and 1809 of the Agricultural Experiment Station, The Pennsylvania
State University, University Park, Pennsylvania. Portions of this
research were supported by funds from Demonstration Project Grant
WPD 95-01 received initially from the Division of Water Supply and
Pollution Control of the Department of Health, Education, and
Welfare and subsequently from the Federal Water Pollution Control
Administration, Department of the Interior. Partial support was
also provided by the Office of Water Resources Research, USDI, as
authorized under the Water Resources Research Act of 1964, Public
Law 88-379 and by the Pinchot Institute for Environmental Forestry
Research, Forest Service, USDA.
REFERENCES
Kardos, L. T. 1971. Recycling sewage effluent through the soil
and its associated biosysterns, Proc. Int. Symp. on Ident. and
Measurement of Environmental Pollutants, pp 119-123, Ottawa,
Ontario, Canada.
Lutz, H. J. and R. E. Chandler. 1946. Forest Soils, John Wiley
and Sons, Inc. New York, 514 pp.
Melton, R. E. 1972. Personal communication.
Myers, E. A. 1973. Sprinkler irrigation systems: design and
operation criteria, Recycling Treated Municipal Wastewater
and Sludge Through Forest and Cropland, The University Press.
Parizek, R. R., L. T. Kardos, W. E. Sopper, E. A. Myers, D. E. Davis,
M. A. Farrell, and J. B. Nesbitt. 1967. Waste water renova-
tion and conservation, Penn State Studies No. 23, 71 pp.
Sopper, W. E. 1971. Effects of trees and forests in neutralizing
waste. In Trees and Forests in an Urbanizing Environment,
Coop. Ext. Service, Univ. of Massachusetts, p. 43-57.
Stone, E. L. and G. Baird. 1956. Boron level and boron toxicity
in red and white pine, Jour, of Forestry 54:11-12.
269
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ANATOMICAL AND PHYSICAL PROPERTIES OF RED OAK AND
RED PINE IRRIGATED WITH MUNICIPAL WASTEWATER
W. K. Murphey, R. L. Brisbin, W. J. Young, and B. E. Cutter
School of Forest Resources
The Pennsylvania State University
The amelioration of the mineral content of treated sewage
effluent by the forest has been demonstrated (Sopper, 1971). The
utility of the forest as a receptor for this effluent could be
increased if beneficial tree response occurred. This forest could
become an important fiber source if the irrigation resulted in
increased growth, more uniform fibers, or fibers which had attributes
sought by the papermakers. Primarily, the papermaker would like to
have long, thin-walled cells with which to work. With this in mind,
two studies were established in which the individual cells produced
by effluent-irrigated trees were measured.
Red pine (Pinus resinosa Ait.) plantations were irrigated,
beginning in 1963,(Table"!}" with effluent throughout the growing
season at rates of one and two inches per week from spraying heads
42 feet above the forest floor. Another two-inch application, begin-
ning in 1964, utilized spraying heads on five foot risers. Specific
gravity, mean annual increment and tracheid dimensions were measured
from the growth rings developed throughout the period of irrigation
and compared to those of nonirrigated wood grown during the same time
or wood grown during a similar period immediately prior to irrigation.
Red oak (Quercus rubrji L.) trees irrigated throughout the year
beginning in 1965",~at a rate of two inches per week were sampled to
determine if irrigation altered the anatomy of these trees. Compari-
sons were made with wood in the same trees laid down prior to
irrigation.
PROCEDURE
Selection of Sample Trees
Red Pine Study. Eight red pine trees were randomly selected in
1966 from one acre plantation plots irrigated with one-inch or two-
inches per week of municipal wastewater. Control trees were obtained
from adjacent untreated plots. The crown wood and stem wood were
treated as separate populations. Mechanical properties of the wood
were measured using American Society for Testing Material Standards
(Murphey and Brisbin, 1970).
270
-------
tsi
•-4
Table 1. Physical and Anatomical Properties of Red Pine Crown Wood Treatment Mean Separation
at the P £.,0.05 Level by Duncan's New Multiple Range Test
Specific
Gravity^
Plot0 Meand
01
02
U2
Cl
C2
0.335
0.338
0.353
0.369
0.378
Specific
Gravityb
Plot Mean
01
02
U2
Cl
C2
0.333
0.334
0.351
0.361
0.377
Ring
Plot
Cl
C2
U2
02
01
Width
Mean
mm
3.40
4.05
4.49
4.56
4.83
Tracheid
Length
Plot
C2
02
Cl
U2
01
Mean
mm
1.51
1.51
1.53
1.54
1.63
Tracheid
Diameter
Plot
Cl
U2
C2
02
01
Mean
pm
18.62
18.91
19.00
19.62
20.61
Cell Wall
Thickness
Plot
02
U2
Cl
C2
01
Mean
ym
1.64
1.68
1.70
1.75
1.77
aComputed by the maximum moisture content method.
Computed by the pycnometric method.
^lot 01 - 1 in. irrigated (overhead); plot 02 - 2 in. irrigated (overhead); plot U2 - 2 in.
irrigated (under canopy); plot Cl - 1 in control; plot C2 - 2 in. control.
Any two means not scored by the same line are significantly different.
-------
Red Oak Study. At the end of the fifth growing season after
initiation of treatment, six dominant or codominant red oak trees
were randomly chosen from the natural stand irrigated at a rate of
two inches per week throughout the year. Also, six control trees
were cut from an adjacent nonirrigated area. Treated trees ranged
in age from 30 to 58 years. The felled trees were bucked at 4,
10, 20, 30, and 40 foot heights. Discs were removed and the north
face marked for orientation. Material was stored at 0° F until
sectioned.
Cell Dimensions
The same procedure was utilized for all of the fiber measure-
ments. Cell lengths were measured from macerated samples removed
from each growth ring. Splinters were cooked at 135° C for 35
minutes in a solution of triethylene glycol and paratoluene
sulfonic acid (Burkhart, 1966). After maceration, complete fiber
separation was accomplished by shaking the sample in a container
with distilled water and glass beads. The individual fibers were
washed thoroughly then randomly retrieved and mounted in a glycerin
jel on glass slides. A microprojector was used to project each
slide on a screen using Technical Association of Pulp and Paper
Industries (TAPPI) T232-SU68, except that each fiber was measured.
Twenty-five tracheids were sampled for each growth ring position.
Cross Sections
Cell cross sections and cell wall thickness measurements were
made from microtome sections prepared by dehydrating the designated
block by passing it through increasing, concentrations of absolute
alcohol, prior to embedding in celloidin and sectioning. Sections
10-micrometers thick were cut, and celloidin removed by washing
with ether. The sections were then stained with safranin and fast
green and mounted. A compound microscope equipped with a filar
micrometer was used to obtain the 25 measurements made for each
growth ring and cell element investigated for each quadrant.
Ring Width Measurements
Individual ring widths were measured on green discs using a
De Rouen Dendrochronograph. Two measurements at right angles to
each other were made across the diameter of each disc, resulting in
four ring width measurements for each disc. Data reported are the
mean annual increment values.
272
-------
Specific Gravity Determination
The specific gravity or density of each growth ring was deter-
mined by using one or two of the several techniques available. The
maximum moisture content procedure (Smith,19S4) or the standard
pycnometric procedure was used for the small material obtained from
some of the growth rings, particularly the red pine material. The
wider growth rings found in the red oak were measured using the
ovendry weight-ovendry volume by water immersion technique. Thirty-
two observations were made for each mean red pine density value.
One hundred and twenty measurements were represented in each mean
calculated in the red oak study.
Abnormal Wood
The procedures outline above were conducted to insure no
abnormal (compression or juvenile wood in red pine or tension wood
in red oak) existed in the samples. Static bending tests, specific
gravity determinations and shrinkage values support the contention
that no abnormal wood existed in any of the material sampled.
Control Material
In both the red pine and red oak studies specific gravity
deteiminations of the wood grown during the period prior to irriga-
tion indicated that the mean density of the trees grown on the treated
and untreated areas were not the same. Since this control period
density was not comparable for differences existing prior to treat-
ment for trees located in designated plots, data from control trees
were not used. The material that was then used as a control was that
wood grown prior to treatment in each of the treated trees. Thus,
all data are within tree comparisons. The exception, of course, is
the crown wood data where comparisons had to be made between material
obtained from treated and untreated red pine trees.
RESULTS
Each variable measured was subjected to analysis of variance.
If a difference existed between treatments at the P 2- 0.05 level,
Duncan's Modified (Bayesian) least significant difference test (1965)
was conducted. The results are shown in the following Tables.
Red pine crown wood response to one-inch irrigation is the most
striking (Table 1). Although the plot 01 specific gravity is
significantly less than all others except plot 02, the ring width
and tracheid length are significantly greater than any of those of
any other treatment. Tracheid diameters are comparable to those
273
-------
developed in the two-inch overhead irrigation treatment plot while
cell wall thickness is comparable to the two-inch control.
Density is definitely affected by the irrigation with the
municipal wastewater. Also notable is the median position of the
specific gravity of the plot receiving two inches per week on the
undergrowth. Perhaps this is a development associated with the
relatively high mineral content of the irrigation water placed on
the forest floor rather than on the canopy.
The red pine stem wood means are listed in Table 2. Comparisons
are made only between irrigation and pre-irrigation stem wood within
plots. Growth rate and tracheid length prior to irrigation did not
differ from that during irrigation. Specific gravity for 01 and U2
plots increased due to irrigation. The 02 plot receiving 2 inches
per week had significantly lower specific gravity. Generally
tracheid diameter increased and cell wall thickness decreased when
the red pine was irrigated. Differences were statistically signifi-
cant except for the tracheids from the red pine receiving 1-inch
per week and the latewood of the trees from the U2 plot.
The red oak data shown in Table 3 demonstrated the more complex
anatomy of this ring porous species. Those average percent change
values listed are those where differences existed at the P — 0.05
level. Statistically significant changes in anatomy occurred in
all but two of the variables measured--fiber cell wall thickness and
broad ray width. Percent change was calculated by using the before-
treatment mean as the base. From it the during-treatment value was
subtracted. The resulting value was divided by the base value and
the answer multiplied by 100 to arrive at the percentage. Signifi-
cance was obtained by analysis of variance and Duncan's test on the
mean values.
DISCUSSION
A review (Sopper,1971) of applications of municipal and
industrial wastewater on forest and crop lands is indicative of the
lack of regard for the response and possible utility of trees
receiving such irrigation. Little work has been done regarding the
effects of combined fertilizer and irrigation treatments on forest
trees. Smith et al (1972) in a study of six-year-old slash pine
found irrigation pTus fertilization increased the growth rate with
no effect on the specific gravity. In our study the red pine crown
wood response to irrigation by the mineral rich effluent was an in-
crease in growth rate with significant decrease in specific gravity.
Zahner (1962) examined five-year-old loblolly pine grown under two
soil moisture regimes. Trees grown in drought conditions had a
higher percentage of summerwood and reduced growth when compared to
those trees growing on near field capacity soil. Zobel, Kellison
274
-------
Table-2. Physical and Anatomical Properties of Red Pine Stem-Formed Wood Grown on Irrigated Plots
Plot Period
01
01
to 02
Cn
02
U2
TJ2
Prior to irrigation
Irrigated0
Prior to irrigation
Irrigated
Prior to irrigation
Irrigated
Specific
gravity
0.401
0.408
0.379
0.367
0.387
0.408
Mean
annual
increment
2.81
2.99
2.81
2.50a
2.40
1.74
Tracheid
length
mm
2.93
2.63
3.07
2.84
3.02
3.14
Tracheid
diameter
Earlywood Latewood
urn
38.00
38.81
37.36
38.20
37.62
38.84
vim
34.41
34.82
33.73
34.79
34.00
34.82
Cell wall
thickness
Earlywood Latewood
vim
2.37
2.35
2.00
1.91
1.83
1.77
von
6.12
5.79
5.10
4.48
5.00
4.64
aControl plot mean annual increment during the treatment period was: Cl = 2.37 mm, C2 = 2.95; neither value
is significantly different at the P •£- 0.05 level from corresponding treated plot. Prior to irrigation,
control plot growth was Cl = 2.89mm and C2 = 3.59mm. The C2 plot grew at a significantly greater rate
than all other plots prior to irrigation.
Growth rings 5,6,7, and 8 from bark.
cGrowth rings 1 and 2 from bark.
-------
Table 3. Response of Red Oak to Irrigation by Municipal Wastewater
and the Treatment Effect on Anatomical Properties
Variables
EW3 vessel segment length (mm)
EW vessel segment diameter (mm)
EW vessel cell wall thickness (ym)
LTr vessel segment length
LW vessel segment diameter (mm)
LW vessel cell wall thickness (pm)
Fiber length (mm)
Fiber diameter (ym)
Fiber cell wall thickness (vm)
Broad ray number
Broad ray height (mm)
Broad ray width (mm)
Growth ring width (mm)
Specific gravity (0. D. volume)
Percent EW
Percent LW
Before
treatment
0.339
0.255
7.44
0.472
0.079
8.49
1.360
13.83
4.92
17.04
7.16
0.377
2.55
0.634
44.9
55.1
During
treatment
0.441
0.242
8.42
0.504
0.076
9.05
1.427
14.11
4.92
21.02
7.56
0.369
4.18
0.664
25.2
74.8
Average
change*
+30
-5
+13
+7
+4
+7
+5
—
—
-24
+6
—
+63
+5
-44
+36
*Percentage shown is significant at P >. 0.05 level.
^ = earlywood
LW = latewood
276
-------
and Kirk (1972) examined wood properties of the crown wood and
juvenile wood and compared them to 25-year-old loblolly and slash
pines. They found crown wood of mature trees low in specific gravity
compared to that of the stem wood. Tracheid dimensions were also
less than mature stem wood but tracheid length was greater than
juvenile wood. Brunden (1964) states crown wood and stem wood are
separate populations. This study confirms the properties of red pine
crown and stem wood must be considered separately. Thus no combining
of data would be in order. Tracheids are altered favorably if paper
pulp is the intended use of the wood. Paper properties related to
fiber-to-fiber bonding are improved because the lower density,
thinner-walled tracheids conform better in a paper sheet.
The red pine stem wood response to irrigation by municipal
wastewater was an increase in density with no change in ring width,
except in those trees irrigated from 5-foot risers, or tracheid
length. Again the literature related to irrigation plus fertiliza-
tion is sparce. Most of that which is available concerns non-porous
species. Howe (1968) attributed an increase in specific gravity to
irrigation of ponderosa pine. Larson (1957, 1963) and Van Buijtenen
(1958) state specific gravity increased due to heavy summer precipi-
tation but decreased if heavy spring precipitation occurred. Appli-
cation of fertilizers resulted in the decrease of specific gravity
(Williams and Hamilton 1961, Siddiqui, Gladstone and Marton 1972,
Zobel et al 1961). Specific gravity increased in two treatments
(01 aricTUiZy and decreased in the third (02). This overhead 2-inch
plot was reported to have been dying and infrared pictures of the
area indicated these trees were not normal. The plot was blown down
the winter following sampling. Posey (1964) reported tracheid
length was reduced I to 10 percent in fertilized loblolly pine while
tangential tracheid diameter was uneffected. Cell wall thickness
was reduced in the fertilization studies. Zobel et al^ (1961) found
no differences in tracheid length as a result of fertilization. The
1-inch per week rate did not effect tracheid diameter or earlywood
tracheid wall thickness. Latewood tracheid thickness was reduced.
Those trees receiving 2-inches per week developed wider tracheids
with reduced cell wall thickness. Tracheid length was unchanged in
trees irrigated at both levels in this study. Tracheid diameters
ranged from unchanged in the 1-inch application to an increase of
six percent in latewood tracheids in trees from the U2 plot.
There is much less literature concerning irrigation and ferti-
lizer effects on ring-porous wood than on non-porous wood. Broadfoot
(1964) found radial growth increased significantly in several hard-
woods when irrigated. Mitchell (1972) reported similar response to
nitrogen for several species of hardwoods and from his study con-
cluded, where valid comparisons could be made, there was a trend
toward increasing specific gravity with increasing growth rate.
Saucier and Ike (1972) state specific gravity and fiber length of
young sycamore are positively correlated with rate of growth. Stand
277
-------
thinning rather than nitrogen accounted for growth in their study.
They also concluded the proportional values of fibers, vessels and
rays were unaffected by growth rate. Aspen response to irrigation
and fertilization reported by Einsphar* Benson and Harder (1972)
was considerable. A 140 percent increase in volume occurred in
trees in the fertilizer plus water treatment series when compared
to the untreated control. Specific gravity was significantly
lower. Tissue composition remained the same while fiber length was
greater in trees grown in irrigated plot and this increase in fiber
length was related to total height of trees. In our study tissue
composition did change; however, rio statistical relationship
existed between any dependent variable when height was the indepen-
dent variable.
Positive changes occurred in the red oaks due to irrigation
with effluent. The five percent reduction in earlywood vessel
segment diameter may reduce a problem associated with pulps from
ring porous woods. These large barrel-shaped elements are causes
of "picking"; the lifting of the surface of paper during printing.
The smaller, longer cell may be less likely to pick. Unlike the
sycamore (Saucier and Ike 1972)^ a change in tissue composition did
occur in the red oaks. 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 in-
crease in number and height of broad rays would cause an increase
in the percentage of "fines" in a pulp mix. Increase in specific
gravity and particularly the chajige in the amount, of latewood from
about one-half to three-quarters of 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
segment length also increased the utility of this wood f6r pulp.
Wangaard and Williams (1970) have shown a relationship exists between
fiber 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.
Horn (1972) shows a curvelinear relationship exists between
burst strength and a ratio between fiber length (L) and cell wall
thickness (T) for twelve western softwoods. Although these data
are not directly applicable, the probability that a similar rela-
tionship exists with the red pine tracheid and red oak fibers and
vessel segments is good. Tables 4, 5 and 6 show L/T data for this
study. The changes in the L/T value are not large. Changes in the
L/T ratio: of red pine tracheids similar to those shown by Horn (1972)
would result in a five to eight percent increase in burst strength
of paper. Also, tracheids from those plots where a significant
reduction in cell wall thickness took place should conform better
in the paper sheet. In the red pine, differences in L/T between
278
-------
Table 4. Red Pine Crown Wood Fiber Length to Cell Wall Thickness
Ratio Values
Fiber Cell wall Ratio
Plot length thickness L/T
mm ym
01 1.63 1.77 920.9
02 1.51 1.64 920.7
Cl 1.53 1.70 900.0
C2 1.51 1.75 862.9
U2 1.54 1.68 916.7
279
-------
Table 5. Red Pine Stem Wood Fiber Length to Cell Wall Thickness Ratio Values
OO
O
Plot
01
01
02
02
U2
U2
Period
Prior to irrigation
Irrigated
Prior to irrigation
Irrigated
Prior to irrigation
Irrigated
Fiber
length
mm
2.93
2.63
3.07
2.84
3.02
3.14
Cell wall
Earlywood
um
2.37
2.35
2.00
1.91
1.90
1.77
thickness
Latewood
von
6.12
5.79
5.10
4.48
4.85
4.64
Ratio
Earlywood
um
1236.3
1119.1
1535.0
1486.9
1589.4
1774.0
L/T
Latewood
um
478.8
454.2
601.9
633.9
622.6
676.7
-------
Table 6. Red Oak Fiber Length to Cell Wall Thickness Ratio Values
Period
Prior to irrigation
Irrigated
Vessels
Earlywood
V
Length
mm
0.34
0.44
Cell wall
thickness
urn
7.4
8.4
L/T
45.9
52.4
Latewood
Length
mm
0.47
0.50
Cell wall
thickness
ym
8.5
9.1
L/T
55.3
54.9
Length
mm
1.36
1.43
Fibers
Cell wall
thickness
nm.
4.9
4.9
L/T
277.6
291.8
ISJ
00
-------
plots prior to irrigation are indicative of the problem confronting
us when making inferences from the data. These trees on the various
plots were not similar prior to irrigation thus all inferences must
be made within a plot.
One other attribute developed by the xylem grown during irri-
gation by municipal wastewater is a reduction in the variability
about the mean for most cell dimensions measured. Megraw and Nearn
(1972) in a study of fertilized Douglas fir stated a reduction in
range of within-ring densities should contribute favorably to pulp
characteristics.
CONCLUSIONS
The technique of using the forest to ameliorate treated sewage
plant effluent while charging the ground water can alter the proper-
ties of the wood being produced. Primarily this study was concerned
with the utility of wood grown in such a forest for pulp wood. The
anatomy of two species studied responded in a similar manner as
that reported in the related but not comparable literature. The
morphology of the pulp fiber is important in the strength and con-
formity of the paper sheet and, therefore, the utility of the pulp.
Alteration of the dimensions of the pulp fibers by the wastewater
were such as to enhance their use as a raw material for paper. The
lack of a separate control area did restrict the findings; however,
the following conclusions may be made:
1. The response to irrigation by 2 inches of municipal waste-
water weekly by red pine crown wood was a lower specific gravity,
greater ring width, and no change in tracheid length. The red pine
irrigated at 1-inch per week had longer tracheids, and larger,
thicker cell walls than the red pine irrigated with 2 inches or the
red pine receiving no irrigation.
2. Specific gravity of stem wood of red pine increased in two
treatments (01 and U2) and decreased in the third (02). Tracheid
length and ring width were unaffected. Increases in earlywood and
latewood tracheid diameters occurred in the trees receiving the 4-
year, 2-inch per week applications and in the latewood tracheid
diameter of the 3-year, 2-inch per week plot. Latewood tracheid
cell wall thickness decreased as a result of irrigation by municipal
wastewater.
/
3. Red oak responded favorably to irrigation at the 2-inch
per week rate. Specific gravity, percent latewood, and cell
dimension changes are considered plus factors in the utility of
the material for wood pulp.
282
-------
The results of these experiments indicate that a 1-inch
spray enchanced the fiber properties of red pine. A 2-inch
application of the effluent was beneficial if red oak is to be used
as a pulp species.
4. If similar projects are to be considered, the multiple
relationships of crop response, wastewater amelioration and other
facets demonstrated by this entire study should consider effects
on forest products, particularly as a wood pulp source in the
initial planning. This would permit more inferences regarding the
xylem of those trees studied.
REFERENCES
Broadfoot, W. M. 1964. Hardwoods respond to irrigation, Jour.
Forestry 62:579.
Brunden, M. N. 1964. Specific gravity and fiber length in crown-
formed and stem-formed wood, Forest Prod. Jour. 14(1): 13-17.
Burkhart, L. F. 1966. New technique for maceration of woody tissue,
Forest Prod. Jour. 16(7):52.
Duncan, D. B. 1965. A Bayesian approach to multiple comparisons,
Technometrics. 7:171-222.
Einsphar, D. W., M. K. Benson, and M. L. Harder. 1972. Influence
of irrigation and fertilization on growth and wood properties
of quaking aspen. Proc. of the Symp. of the Effect of Growth
Acceleration on the Properties of Wood. U.S. Dept. Agric.
Forest Service, Forest Products Lab., Madison, Wisconsin.
Horn, R. A. 1972. Fiber morphology considerations in paper
properties. Proc. of the Symp. on the Effects of Growth
Acceleration on the Properties of Wood, U.S. Dept. of Agric.
Forest Service, Forest Products Lab., Madison, Wisconsin.
Howe, J. P. 1968. Influence of irrigation on ponderosa pine.
Forest Prod. Jour. 18(l):84-93.
Larson, P. R. 1957. Effect of environment on the percentage of
summerwood and specific gravity of slash pine, Yale Univ.
School Forestry Bull. No. 63.
Larson, P. R. 1963. The indirect effect of drought on tracheid
diameter in red pine, Forest Sci. 9(l):18-27.
Megraw, R. A. and W. T. Nearn. 1972. Detailed DBH density profiles
of several trees from Douglas-fir fertilizer/thinning plots,
Proc. of the Symp. on the Effect of Growth Acceleration on the
Properties of Wood, U.S. Dept. Agric. Forest Service, Forest
Products Lab., Madison, Wisconsin.
Mitchell, H. L. 1972. Effect of fertilizer on the growth rate and
certain wood quality characteristics of sawlog red oak,
yellow poplar, and white ash, Proc. of the Symp. on the
Effect of Growth Acceleration on the Properties of Wood, U.S.
Dept. Agric. Forest Service, Forest Products Lab., Madison,
Wisconsin.
283
-------
Murphey, W. K. and R. L. Brisbin. 1970. Influence of sewage plant
effluent variagation on crown wood and stem wood of red pine,
Pa. Agric. Expt. Sta. Bull. 772.
Posey, C. E. 1964. The effects of fertilization upon wood
properties of loblolly pine, (Pinus taeda L.), North Carolina
State College School of Forestry^Tech. Report No. 22, 62pp.
Saucier, J. R. and A. F. Ike. 1972. Response in growth and wood
properties of American sycamore to fertilization and thinning,
Proc. of the Symp. on the Effect of Growth Acceleration on the
Properties of Wood, U. S. Dept. Agric. Forest Service,
Forest Products Lab., Madison, Wisconsin.
Siddiqui, K. M., W. T. Gladstone, and R. Marton. 1972. Influence
of fertilization on wood and pulp properties of Douglas-fir,
Proc. of the Symp. on the Effect of Growth Acceleration on
the Properties of Wood, U.S. Dept. Agric. Forest Service,
Forest Products Lab., Madison, Wisconsin.
Smith, D. M. 1954. Maximum moisture content method for determining
specific gravity of small wood samples, U.S. Dept. Agr. Forest
Service, Forest Prod. Lab. Report No. 2014.
Smith, D., H. Wahlgren, and G. W. Bengtson. 1972. Effect of
irrigation and fertilization on wood quality of young slash
pine, Proc. of the Symp. on the Effect of Growth Acceleration
on the Properties of Wood, U.S. Dept. Agric. Forest Service,
Forest Products Lab., Madison, Wisconsin.
Sopper, W. E. 1971. Effects of trees and forests in neutralizing
waste, Trees and Forest in an Urbanizing Environment, Univ.
of Mass. Cooperative Ext. Service.
Van Buijtenen, J. P. 1958. Experimental control of environmental
factors and their effect on some aspects of wood anatomy in
loblolly pine, TAPPI 41(4):175-178.
Wangaard, F. F., and D. L. Williams. 1970. Fiber length and fiber
strength in relation to tearing resistance of hardwood pulps.
TAPPI 53(11):2153-2154.
Williams, R. E. and J. R. Hamilton. 1961. The effect of fertilization
on four wood properties of slash pine, Jour. Forestry
59(9):662-665.
Zahner, R. 1962. Terminal growth and wood formation by juvenile
loblolly pine under two soil moisture regimes. Forest Sci.
8(4):345-352.
Zobel, B. J., J. F. Goggans, T. E. Maki, and F. Hensen. 1961.
Some effects of fertilizers on wood properties of loblolly
pine, TAPPI 44(3):186-192.
Zobel, B. J., R. C. Kellison, and D. G. Kirk. 1972. Wood properties
of young loblolly and slash pine, Proc. of the Symp. on the
Effect of Growth Acceleration on the Properties of Wood, U.S.
Dept. Agric. Forest Service, Forest Products Lab., Madison,
Wisconsin.
284
-------
DISCUSSION
Mace; Did you conduct tests relative to the strength properties?
Cutter: Yes. We did.
Mace: Was it positive or negative for red oak?
Cutter: For red oak it was negative. The modulus of elasticity
and modulus of rupture was decreased. We conducted
strength properties on both the red pine and the red oak.
In the red oak, the specific gravity was increased. You
might expect strengths to increase also but it did not.
It was decreased as a result of the irrigation with sewage
effluent.
285
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DEER AND RABBIT RESPONSE TO THE SPRAY
IRRIGATION OF CHLORINATED SEWAGE EFFLUENT
ON WILD LAND
G. W. Wood, D. W. Simpson and R. L. Dressier
School of Forest Resources
The Pennsylvania State University
That chlorinated sewage effluent can be renovated and re-
cycled to the ground-water table by spray irrigation on agronomic
and forest lands appears to have been well documented. Three
important gains from this wastewater disposal method are recognized:
(1) conservation of the water resource, (2) elimination of a
stream pollution source, and (3) increased crop production on
the irrigation sites.
While the water, soil, and floral response to wastewater
irrigation have been intensively studied, very little attention
has been paid to faunal response. The latter will be of tre-
mendous importance in environmental impact statements presented
to the public where this treatment system might be deployed. If
there is a general belief among the public that this type of land
treatment is deleterious to wild birds and mammals, there is
small chance that it will be instituted on a large scale. This
is primarily true, of course, where the system would be deployed
on publicly-owned land. In fact, the institution of the current
studies of faunal response to wastewater irrigation was a result
of just such sentiment regarding the use of Pennsylvania State
Game Lands 176 for expansion of the Penn. State Wastewater
Renovation Facility.
OBJECTIVES
The first efforts in evaluating the effects of sewage
effluent irrigation on wild animals have been directed toward the
principal game species on the treatment areas. The cottontail
rabbit (Sylvalagus floridanus) and the white-tailed deer
(Odocoileus yirgiriianus) are rated as high priority species by
hunters using State Game Lands 176. The first objective was to
determine changes in the nutritive value of rabbit and deer foods
that were caused by the irrigation treatment. The second ob-
jective was to determine the effects of the treatment on deer
feeding behavior. That is, do the deer feed on treated sites as
readily as untreated sites? Thirdly, it was intended to
determine whether or not rabbits could reproduce and survive if
they were restricted to treatment sites.
286
-------
PROCEDURES
Changes in nutritive values of foods were evaluated
by simultaneously collecting samples of plant parts by species
known to be used as a food source by rabbits and/or deer at
various times of the year. These samples were then dried
at 65°C for 72 hours, ground in a Wiley mill, subsequently
analyzed for crude protein, phosphorus, potassium, calcium,
and magnesium. Crude protein determinations were by macro-
Kjeldahl methods; P by the vanadomolydophosphoric acid method
(Jackson, 1958), and K, Ca, and Mg by atomic absorption
spectropho tome try.
Digestion trials of a standard lab ration for rabbits and
of alfalfa^hay were run using adult female wild rabbits. These
foods were used as standards for comparison of trials using Reed
canarygrass from both treated and untreated sites. The digestion
coefficients (DC) were calculated by the equation:
DC = wt. of material ingested - wt. of material in feces
wt. of material ingested
Deer feeding behavior studies are being done using the lead
deer technique which was developed at Perm State some 10 years
ago. Three animals, one two-year-old male, a yearling male, and
a yearling female, have been and are continuing to be used as study
animals. Each animal is transported to the study area two to
three times each week and observed for a 90-minute period. The
study area is 10.2 acres in size. Five acres receive two inches
of chlorinated sewage effluent during an eight-hour period each
week. An adjacent 5.2 acres serves as the control. The plants
that the animals are observed utilizing as food, the time (in
seconds) spent feeding on each of these plants, and the time spent
on treated and untreated sites are recorded by the observer.
Preference for foods by individual species and foods in general
on variously treated sites are calculated by the following
equation:
Food biomass on site X
Food biomass on total study area
Preference =
Time spent feeding on site X
Total time spent feeding
Cottontail rabbit reproduction and survival studies on animals
restricted to treatment sites receiving two inches of effluent during
a 16-hour period each week have been carried on since May, 1971.
287
-------
The study method has been to construct four 4-acre rabbit enclosures,
two of which are treated and two untreated. The animals in each
of these enclosures are periodically trapped, marked for identifica-
tion, examined for nutritional condition, and released. Trapping
has been done using the Mosby-type box trap with a trap density
of ten per acre.
RESULTS AND DISCUSSION
Tables 1, 2, and 3 list a total of 32 plant species that
were analyzed for total nutrient concentrations. In general,
the crude protein, P, K, and Mg concentrations were higher on
irrigated sites than adjacent control sites. The opposite was
true for Ca. In all but four cases Ca concentrations were ap-
parently lowered by the irrigation treatment.
It will be noted that the greatest differences in nutrient
concentrations between treated and untreated sites occur among
the plants sampled in the summer and the smallest differences be-
tween those sampled in the winter. This is not surprising since
summer foods of wild herbivores are primarily composed of perennial
and annual herbs, deciduous foliage, and unhardened current woody
growth. These all have high proportions of active meristematic
tissue, already high in nutrient concentrations, and presumably
serves as a deposition site during luxury consumption of avail-
able nutrients. Although the differences between areas are not
as pronounced during the fall and winter, there still appear to
be real differences for many nutrients. That is, concentrations
are still higher in winter although to a lesser extent than in
sunnier.
Table 4 presents the results of several digestion trails on
rabbit foods. As previously mentioned a standard lab ration for
rabbits and alfalfa hay were run as references.
Obviously Reed canarygrass is not as good a food as either of
the two from the standpoint of dry matter digestibility. On the
other hand, the crude protein concentration is quite adaquate and
the plant is used as a food source to some extent in agricultural
areas. Analysis of the effects of irrigation on its digestibility
shows that treatment resulted in no significant changes in per-
centage of digestible dry matter or crude protein.
Studies of white-tailed deer feeding behavior in relation to
the irrigation treatment indicate that the animals use treated sites
at least as readily as untreated sites. Table 5 lists the pre-
ference indices based on available food biomass from May 1 to
June 15 and relative sizes of study sites. When all three test
288
-------
Table 1. Percentage Concentrations of Nutrients in Forages Collected in Pole-Sized Mixed-Oak
Stands Irrigated with Two Inches of Sewage Effluent per Week (T) and on Adjacent
Untreated Sites (U)
oo
<£>
Species Plant Part
White Oak
(Quercus alba)
Flowering dogwood
(Cornus Florida)
Red Oak
(Q. rubra)
Chestnut
(Castanea dentata)
leaves
leaves §
twigs
leaves
leaves
Sassafras leaves §
(Sassafras albidum) twigs
Bracken fern
(Pteridium Aquilinum)
Whorled loostrife
(Lysimachia
quadrifblia)
fronds
leaves §
stems
Treat-
ment
T
U
T
U
T
U
T
U
T
U
T
U
T
U
Month of
Collection
July
July
July
July
July
July
July
Crude
Protein
22.8
16.9
21.6
12.9
16.2
14.6
20.2
17.2
32.2
19.7
29.4
14.5
25.9
16.1
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
P
268
220
414
208
227
174
300
215
541
274
808
203
573
237
0.
0.
1.
0.
0.
0.
0.
1.
2.
2.
5.
3.
4.
3.
K
843
790
658
902
694
673
976
007
824
569
421
296
820
562
Ca
1.29
1.85
3.55
3.91
0.63
1.24
1.06
1.24
0.89
1.32
0.53
0.64
0.77
0.73
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Mg
.33Z
.195
.721
.422
.220
.142
.510
.329
.285
.229
.376
.283
.340
.220
-------
Table 1. Cantinued
to
O
Species
Huckleberry
(Gaylussacia sp.)
Black cherry
(Prunus serdtina)
Red maple
(Acer rubrun)
Teaberry
(Gaultheria
procumbens)
Pokeberry
(Phytolocca
Plant Part
leaves §
twigs
leaves §
twigs
leaves §
twigs
leaves §
stems
leaves §
stems
Treat-
ment
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
T
Month of
Collection
July
Sept.
July
Sept.
July
Sept.
July
Sept.
July
Sept.
Crude
Protein
14.0
12.0
12.3
12.4
24.8
17.3
19.6
16.0
20.4
11.9
17.5
11.4
11.8
9.0
11.3
9.4
40.2
32.4
P
0.188
0.157
0.119
0.101
0.323
0.336
0.195
0.233
0.444
0.191
0.389
0.124
0.224
0.128
0.134
0.085
0.552
0.451
K
0.705
0.787
0.479
0.565
1.383
1.973
0.444
0.831
1.105
0.748
0.539
0.308
0.819
0.718
0.317
0.277
9.383
4.159
Ca
0.87
0.97
1.21
1.48
1.66
1.82
1.32
1.83
1.43
1.20
1.39
1.22
1.20
1.95
1.23
1.89
0.76
0.94
Mg
0.311
0.209
0.353
0.191
0.546
0.455
0.400
0.303
0.511
0.233
0.408
0.199
0.372
0.274
0.407
0.279
1.105
1.439
americana)
-------
to
Table 2. Percentage Concentrations of Nutrients in Forages Collected in Aspen-White Pine Stands
Treated with Two Inches of Sewage Effluent per Week (T) and on Adjacent Untreated
Sites (UQ in October 1971
Species
—— ^ • - •• rr — -r - -i - — - -
Striped Pipsissewa
(Chimaphila maculata)
Pipsissewa
(C. cisatlantica)
Partidgeberry
(Mitchella repens)
Ground Cedar
(Lycopodiun tristachyum)
Sheep sorrel
(Rumex acetosella)
Strawberry
(Fragaria sp.)
Goldenrod
(Solidagp sp.)
Yellow mustard
(Brassica rapa)
Plant Part Treatment
I^^MIHM*VHVi^^tf^MI1BHI^BVMai^a«IW-B*^^^^BMA*V4^«IMi^HHM*^^^V^^Ha^MMM
leaves §
stems
leaves §
stems
leaves §
stems
leaves §
stems
leaves
leaves §
stems
leaves
leaves
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
Crude
Protein
^•H«fp^H^HWHi-^»^w--^M«v^^^MI
16.6
14.7
12.3
10.2
13.8
9.6
9.7
7.0
19.0
15.6
15.7
11.0
14.3
9.4
17.6
15.3
P
^••^•^^••••••^•b^MBWHBIHtf
0.256
0.267
0.218
0.206
0.165
0.234
0.143
0.101
0.767
0.254
0.601
0.408
0.366
0.153
0.509
0.431
K
>^Vh«^^Mta^vBavvv»^M_IH
0.386
0.558
0.125
0.379
0.892
0.774
1.142
1.017
2.175
1.878
1.278
0.521
2.500
1.278
4.454
4.673
Ca
W^M^— ^M^MVBhHW^M^^MIM
0.938
0.933
1.435
1.300
0.651
1.523
0.209
0.234
0.650
0.654
1.505
1.680
1.160
1.209
1.063
1.141
Mg
-III..I !.—..•. .1. 1 U
0.217
0.137
0.221
0.175
0.472
0.428
0.115
0.170
0.325
0.200
0.305
0.237
0.258
0.153
0.273
0.181
-------
Table 2. Continued
t-o
<£>
Species
Plantain
(Plantago lanceolata)
Broadleaf plantain
(P. major)
Birdsfoot trefoil
(Lutus corniculatus)
White clover
(Trifolium repens)
Wood sorrel
(Qxalis sp.)
Virginia creeper
(Parthenocissus quinquefolia)
Bigtooth aspen
(Populus grandidentata)
Gray dogwood
(Cornus racemosa)
Red maple
(Acer rubrum)
Plant Part
leaves
leaves
seed heads
leaves §
stems
leaves §
stems
leaves §
steins
leaves §
stems
leaves
leaves
leaves
leaves
Treatment
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
U
U
Crude
Protein
12.1
10.2
15.8
10.3
13.9
6.1
24.6
21.0
26.3
25.4
16.2
11.4
12.7
9.0.
14.7
9.4
11.5
S. 9
12.4
10.3
i
P
0.414
0.449
0.365
0.260
0.543
0.267
0.340
0.203
0.395
0.356
0.755
0.815
0.404
0.266
0.267
0.152
0.263
0.287
0.267
0.218
K
2.825
2.595
2.072
0.849
2.500
1.266
1.327
0.514
2.877
1.780 .
1.928
1.761
0.929
0.682
0.308
0.285
0.514
0.324
0.316
0.641
Ca
2.111
2.009
1.935
1.558
0.742
1.231
1.055
1.644
1.097
1.163
1.031
1.624
2.633
2.380
1.486
1.557
2.128
2.229
1.177
1.072
Mg
0.251
0.132
0.427
0.356
0.239
0.158
0.183
0.247
0.315
0.225
0.349
OO O O ""
• £-* OO
0.350
0.391
0.276
0.225
0.371
0.293
0.276
0.179
-------
N)
to
o*
Table 3. Percentage Concentrations of Nutrients in Forages Collected In Aspen-White Pine Stands
Treated with Two Inches of Sewage Effluent per Week (T) and on Adjacent Untreated
Sites (U) in February 1972
Species
Quaking aspen
(Populus tremuloides)
Bigtooth aspen
(P. grandidentata)
Red maple
(Acer rubrum)
Staghorn sumac
(Rhus typhina)
Blackberry
(Rubus alleghenierisis)
Plant Part
bark
browsea
bark
browse
bark
browse
bark
stems
i
twigs0
Treatment
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
T
U
Crude
Protein
8.6
6.3
9.1
9.1
7.3
6.9
10.2
7.5
8.1
6.7
9.8
7.3
10.1
8.7
6.5
5.3
10.7
8.4
P
0.187
0.131
0.207
0.202
0.167
0.138
0.232
0.191
0.124
0.137
0.178
0.156
0.201
0.154
0.139
0.125
0.169
0.142
K
0.652
0.571
0.575
0.601
0.583
0.515
0.682
0.467
0.360
0.337
0.497
0.373
1.317
1.424
0.269
0.332
0.349
0.516
Ca
1.699
1.886
1.677
1.515
2.038
1.702
1.489
1.518
1.420
0.936
1.195
1.768
0.859
0.827
0.489
0.608
0.679
0.794
Mg
0.134
0.104
0.176
0.143
0.147
0.103
0.154
0.167
0.054
0.076
0.099
0.090
0.114
0.110
0.106
0.084
0.161
0.169
aTerminal two inches of twig growth.
Terminal eight inches of twig growth.
-------
Table 4. Digestion Coefficients for Dry Matter and Crude
Protein in Cottontail Rabbits
Forage
Lab ration
Alfalfa hay
Reed canarygrass
Irrigated
Control
No. of
Rabbits
10
7
5
3
Dry Matter
.645 +
.496 +_
.330 +_
.352 +_
.013
.016
.033
.023
Crude Protein
.697 +_
.695 +_
.730 +
.622 +_
.027
.026
.053
.088
Table 5. Indices of Site Preference by Semi-Free Ranging
White- ailed Deer
Irrigated Transition Non-irrigated
Index based on relative site size
All test animals 1.33 0.85 0.59
2-yr-old male 0.94 1.32 0.92
Index based on relative amounts of food
All test animals 1.46 a 0.63
2-yr-old male 1.03 a 0.93
a The transition zone was not recognized in the biomass
sampling.
animals are averaged there appears to be a definite preference for
the treated site. This is probably a spurious relationship,
however, due to the tendency of the two yearling animals to feed
near the unloading area, which happened to be adjacent to
the treated site. These animals did very little investigating of
alternate feeding areas and fed only sporadically during testing
periods. The 2-year-old buck, however, explored and fed readily
on all sites. If anything the 2-year-old showed a preference for
the transition zone between the treated and untreated sites.
294
-------
This is a normal and somewhat predictable deer-use response to
spatial changes in habitat. That is, the edges receive pro-
portionately greater use. Beyond the "edge effect" response the
treated site was used at about the same level as was the untreated.
No lead deer work has been done during the winter period.
Studies of site use by wild deer have been conducted, however,
using snow track and bed counts. Our observations indicate that
the deer readily use irrigated sites during this period of the year
for feeding and especially for resting. Numerous beds have been
frequently observed in close proximity to the delivery sprinklers.
There is some reason to believe that the animals may use the area
during actual irrigation periods because of warmer ambient
temperatures on the site during the spraying of the effluent which
is about 75°F when it leaves the sprinkler.
After 1-1/2 years of studying two populations of rabbits
confined to treatment sites and two populations on untreated sites,
but similar habitat, we are still unable to get a measure of the
influence of irrigation on rabbit reproduction. During the first
year of study we were only able to state that there was at least
some reproduction in all study populations. This was only because
we caught at least one juvenile animal in each area during the
trapping period. Since we started with uneven populations at the
beginning of the study period in the spring of 1971, total popula-
tion estimates in the following fall could give no clue as to
what natural increases or decreases in the populations had occurred.
In an attempt to remedy this situation we adjusted all study popula-
tions to six adult animals (2 males, 4 females) in the spring of
1972. Our summer trapping success in 1972 has been similar to
that of 1971 allowing only the determination that we have some
reproduction in all four populations. Based on our past experience
we should be able to get good trapping success in October and
November. At that time we should at least be able to determine
any net changes in the populations.
Again due to the extreme difficulty of capturing rabbits
during the late spring and summer months we have no measure of the
influence of the irrigation treatment on rabbit survival during
this time. We do have a good measure of winter survival, however.
Table 6 presents the population estimates of the study areas based
on the assumption of total population capture for Fall, 1971 and
Spring, 1972.
Although the percentage survival was higher on non-irrigated
sites (80 percent) than on irrigated sites (70 percent), the
irrigated sites started with a 30 percent greater density and ended
with one still higher by 11 percent. In addition, the animals on
treated sites were superior to those on untreated sites with
respect to nutritional condition. The former were all healthy
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Table 6. Minimum Winter Survival on Irrigated and Non-Irrigated Sites Based on Total Population
Capture in the Fall of 1971, and Number of Recaptures in Late Winter of 1972
tsJ
to
OS
Irrigated site 1
Irrigated site 2
Non- irrigated site 1
Non- irrigated site 2
Number
Males
3
2
2
1
Marked Fall
Females
6
2
3
4
1972
Total
9
4
5
5
Recaptured
Late Winter
1972
Males Females Total
3
2
2
1
4
0
1
4
7
2
3
5
-------
specimens at the end of the winter while the latter were as much
as a third lighter in weight and showing obvious signs of emaci-
ation. This phenomenon can be explained by several observations.
First, it has already been pointed out that the nutritional quality
of the foods available on irrigated sites was higher than that on
non-irrigated sites. Secondly, there was more food available on
treated sites during the winter due to the pulling down of sapling
trees by the ice fomation resulting from the spray irrigation.
Thirdly, the ice mounds are laced with crevices and caves which
offer and are heavily used by the rabbits for cover.
CONCLUSIONS
The spray irrigation of chlorinated sewage effluent at the
rate of two inches per week appears to have a favorable influence
on the nutritive value of rabbit and deer forages. Generally
the crude protein, P, K, and Mg can be expected to be raised
in these forages while the Ca is lowered. Reed canarygrass, the
only forage tested for changes in digestibility due to treatment,
showed no significant response with respect to digestible dry
matter and protein.
Studies using the lead deer technique to determine preference
for or avoidance of irrigated sites and forage from these sites
indicate that the deer use treated sites at least as readily as
untreated sites. During the winter period wild deer do not
avoid the area but appear to use it quite readily for resting and
feeding.
At this time we have no conclusive evidence of the effects
of spray irrigation on rabbit reproduction. We do know that the
winter carrying capacity of treated sites exceeds that of untreated
sites presumably due to higher levels of available nutrition and
improved cover conditions.
DISCUSSION
Unknown: Do you feel that the increase in the numbers of mosquitos
and biting flies will at some time be a limiting factor
as far as the wildlife is concerned in these areas that
are under irrigation?
Wood.: We don't have any good infoimation to indicate that we do
have increases in arthropod populations. We have only
started collecting numerical data on this during the past
year and this has been in relation to all of our studies.
If this kind of thing is happening then we suspect that
there might be a problem because the animal may avoid the
area because of the insect nuisance there. We've seen
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this in other areas. In some of our clearcut areas where
we have deer fenced in and we're looking at the animals
response to habitat changes and plant succession it was
found that in the summer time the animals usually are in
very poor condition. It's just the reverse of what is
expected because of the fly populations in the clearent
areas. It's my belief that the animals are constantly
running trying to brush off the flies in the brush.
Unknown: How about the incidence of disease caused by the flies?
Wood': We have initiated studies on this with a grant from the
Office of Water Resources Research. We take 3 blood
samples a year from these deer. They are compared with
2 other sets of penned deer from which we take blood
samples. Then we also have rabbits which are out in
enclosures in the woods from which we are taking blood
samples to determine if we have a difference in the
appearance of arbor viruses in these animals. We also
are monitoring fecal samples every three days from the
three animals that are used in the field and the three
penned animals. Coliform counts are run on these and the
coliform bacteria serotyped to see if we are getting
correlations between serotypes of E-coli in the effluent
being sprayed on the site and those occurring in the
animal.
Unknown: Do you feel that these data are realistic if these
animals are fed on artifical food and are not really wild
animals?
Wood: This has always been a criticism of lead deer studies and
there have been many modifications made of this. But from
a standpoint of whether the animal prefers or avoids a
particular area or a particular type of food we believe
that the observations are quite good. From the standpoint
of the amount of species preference when you're trying to
get the exact food habits of the animals this may become
limited. However, there have been some studies in the
southwest in Arizona that have shown that animals raised
in pens and taken out onto the range that those animals
were eating the same forages that wild deer that had
never seen a pen were using.
Unknown: Do you know of any data that would indicate the response
of cattle to pastures that have been irrigated with
sewage effluent?
Wood: I'm sorry, I don't.
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SPRINKLER IRRIGATION SYSTEMS: DESIGN AND OPERATION CRITERIA
Earl A. Myers
Department of Agricultural Engineering
The Pennsylvania State University
Wastewater must be applied uniformly over the land surface at
the proper rate in inches per hour and the appropriate amount in
inches per week, if adequate renovation is to be expected. Two
areas which greatly affect this judicious application are proper
design and diligent management.
This paper first lists the variables involved in the design
of an irrigation distribution system, then discusses a nunber of
factors which affect the choice of specific value for each variable,
and concludes with comments concerning the various and sundry
management decisions that must be made when operating the system.
DESIGN VARIABLES
In the design of a solid-set irrigation system for any waste-
water facility, five variables must be considered. These are daily
flow from the facility, weekly loading depth on the land area,
hourly application rate, sprinkler spacing, and nozzle operating
pressure. Each of these variables can be considered to be indepen-
dent, however, they are also strongly interrelated.
The daily flow from the facility in combination with the weekly
loading depth determine the overall size of the irrigation distribu-
tion system. The loading depth usually is expressed in inches of
wastewater applied each week over the entire disposal area. For a
plant outflow of 0.5 mgd (million gallons per day), 64.5 acres are
required if the loading depth per week is 2 inches, whereas, if the
loading depth is only 1 inch per week, 129 acres will be needed.
The 0.5 mgd, 2-inch per week, and 64.5-acre statistics essentially
describe Penn State's arrangement at the present time.
The application rate, expressed in inches per hour, in conjunc-
tion with the loading depth per week establish the number of
irrigation periods per day or per week. Thus, for a 2-inch per week
loading depth if the application rate is 1/4 inch per hour, each
irrigation period would be 8 hours and there could be three irriga-
tion periods per day or 21 periods per week. When using an
application rate of 1/6 inch per hour each irrigation period would
be 12 hours and there could be only two periods per day or 14
periods per week.
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To apply the 0.5 mgd of effluent at the rate of 1/4 inch per
hour required 21 periods in each of which approximately 3.1 acres
were irrigated. After the application rate was changed to 1/6 inch
per hour, 14 periods were required in each of which approximately
4.6 acres were irrigated.
The sprinkler spacing in conjunction with the rate of appli-
cation establish the number of gallons per minute (gpm) each
sprinkler must emit, whereas the sprinkler spacing and the acres
per period establish the number of sprinklers which should operate
at any one time. Let us consider the 1/4 inch per hour application
rate which requires a 3.1-acre area. If we choose a 60 by 80 foot
spacing, 28 sprinklers are needed and each sprinkler should emit
12.5 gpm. Had we chosen a 40 by 60 foot or 80 by 100 foot spacing,
56 or 17 sprinklers would have been required and 6.3 or 21 gpm would
be needed. Penn State's system has used all of these arrangements
and many more.
The fifth variable is the operating pressure at the sprinkler
nozzle. This pressure in conjunction with the required gallons per
minute of the sprinkler determine the diameter of nozzle hole which
is needed. Forty pounds of pressure per square inch (psi) are
required to force 6.3 gpm through a 3/16 inch nozzle, whereas 55
psi are needed for 12.5 gpm through a 1/4 inch nozzle. Nozzle
diameters used on the Penn State project ranged from 3/32 to 5/16
inch, while pressures ranged from 35 to 65 psi.
Figure 1 lists the design statistics for a typical solid-set
irrigation system for a town of 5,000 people. Once a specific
figure has been chosen for each of the five variables, much of the
remaining design becomes mere arithmetic. The primary engineering
involved is in the choice of the proper value for each of the
variables.
FACTORS AFFECTING VARIABLES
Waste>rater Discharge
The above design example considers only wastewater quantity,
which is satisfactory for many municipalities. The quality of the
wastewater, however, in most situations must also be considered.
Irrigation installations using Penn State's "Living Filter" concept
should be utilized only where the wastewater contains pollutants of
such type and concentration that can be removed by the soil-crop
complex. That is, only certain pollutants can be removed appro-
priately by the absorptive, biological, chemical, and physical
reactions within this biosphere. Other pollutants can completely
destroy this living filter, thus producing additional pollution rather
300
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Wastewater discharge (0.5 mgd)
Irrigaticai amount (2 in/wk)«
Irrigation rate (% in/hr>
(64.5 acres).
irrigation
'(21 periods/wk)-
(3.1 acre/period)
;(28 sprinklers/period)
o
Sprinkler spacing (60 x 80 ft)
(12.5 gpm/sprinkler)
Sprinkler pressure (55 psi)-
^(%-inch diameter nozzle)
Figure 1. Typical Solid-set Irrigation System Design Statistics for a Town of 5,000 People.
-------
than renovation. Wastewaters containing high concentrations of
heavy metals, chlorides, toxic constituents, etc. will probably
require special pretreatment before land distribution.
Irrigation Mount
The choice of weekly loading depth depends upon the renova-
tion and hydrologic capabilities of the site relative to the quality
of the liquid wastes applied and the water quality constraints
imposed by the regulatory agency. Most of the work at Penn State
was with an application amount of 100 inches per year applied at
2 inches per week. The material applied was secondary treated and
chlorinated domestic municipal effluent, from the University and from
the Borough of State College.
The renovation capacity of a site depends upon such factors
as the soil and the crop to be grown, whereas the degree of renova-
tion required depends upon the pollutants in the waste water and the
proposed was of the renovated liquid; both must be considered in
selecting the irrigation amount.
Corn and reed canarygrass can remove larger amounts of nitrogen
than legumes or trees. The removal of crops also permits larger
amounts of application. The deeper the soil and the finer the texture
the greater the amounts of phosphorus one can apply because of the
greater total chemical fixation capacity. A two-foot depth of soil
may be adequate since 90% or more of the crop roots are in this layer.
In sandy soils the amount per application period may need to be
decreased so that the nutrients are not carried below the plant root
•zone before they can be used. Soil profiles with controlled shallow
water tables which reach up into the biologically active zone may
remove substantial amounts of nitrogen by denitrification. On such
a site, removal of a harvested crop may not be necessary to obtain
adequate nitrogen removal.
The amount of application may have to be decreased when the
irrigation site is over a domestic water supply aquifer rather than
an aquifer which would be used for agricultural irrigation or some
other less demanding use. The amount of application at any location
must not produce a water table sufficiently higher to cause direct
runoff of untreated water.
The hydrologic capabilities of a site must be considered
independently from the site's renovation ability. While sandy
surface soils will permit infiltration of high rates of application,
the amount one should apply may be controlled by underlying tighter
layers. Some soils can appropriately be drained to receive high
loadings of liquid wastes while others cannot. Fine textured soils
covered with thick stands of vigorously growing hay crops can accept
large amounts of water during the summer months, but may produce
excessive runoff in early spring or late fall at these loadings.
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Since the amount of wastewater applied affects the quantity
and quality of water that will leave the watershed, one needs to
consider the final disposition of the treated water when choosing
the irrigation amount. Final disposition includes potential reuse,
as well as, the rate and quality of discharge.
Reuse of renovated water usually is governed by economics and
by local legal limits. Potential reusers include industrial,
domestic, and agricultural. The renovation requirements for certain
industrial uses, cooling for example, may not be as high as for
domestic uses, therefore, a greater amount can be applied per week
or per year, under certain terrain and soil conditions it may be
possible to treat the effluent in the surface soil and then permit
it to resurface at a lower elevation. After it has returned to the
surface it may be used directly or it may be stored behind large
dams for future use. These reservoirs may also function as
recreational areas. Thus, certain reuses permit greater application
amounts.
The quantity of water recharged often is considered equal to
the amount distributed minus such losses as evapotranspiration
associated with plant growth and as direct evaporation from the
sprinklers. This, however, assumes that the water actually infil-
trates through the soil surface and percolates to the groundwater
reservoir. In many instances on Pennsylvania hillsides covered with
permeable topsoils but slowly permeable subsoils this is not
necessarily true. During the spring thaw and other naturally wet
periods, extensive amounts of water may become interflow or may not
infiltrate at all. Thus, it is imperative that the design and
operation of the system is such that the application amount is
controlled to assure renovation that is adequate for the desired
reuse.
Additional factors pertaining to the hydrologic regime of
irrigated liquid wastes have been described by Parizek and Myers
(1968).
Irrigation Rate
An application rate of 1/4 inch per hour was used for most of
Penn State's systems during the first five years, whereas most of
the present systems have been converted to 1/6 inch per hour. This
lower application rate is preferrable since one often must irrigate
during and after heavy rains, when the crops are very young, in
early spring and in late fall, and when the soil is near or at
field capacity.
There is also a labor advantage with the 1/6 inch per hour rate.
When a manual system is used, a 2-inch application requires a valve
turn every eight hours with a 1/4 inch per hour rate and only every
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12 hours with a 1/6 inch per hour rate. The valves were turned at
8 A.M., 4 P.M., and midnight with the 1/4 inch per hour arrangement,
whereas they are now turned only at 8 A.M. and 8 P.M. This new
arrangement obviously is preferred by the personnel turning valves.
Sandy loam soils are somewhat poorer in inherent nutrients and
more droughty than preferred for regular agricultural purposes.
Since the nutrients and water are supplied by the effluent, however,
these soils are excellent for final distribution of most wastewaters.
They also permit higher rates of application than finer textured
soils and this provides more flexibility in the choice of irrigation
system type.
Additional factors which affect the rate of application
include: soil structure and permeability, soil cover crop and
management procedures, surface topography, and climatic conditions.
Soils having good structure and aggregates which are stable
permit higher rates of application, as do highly permeable soils
which have rapid and continuing internal drainage. Thick hay and
grass cover crops permit a higher application rate than does a bare
soil. Good management provides proper crops and cropping procedures
which help maintain good soil structure and permeability. Steep
surface topography and low temperatures require reduced rates of
application to decrease changes of overland flow and runoff.
Sprinkler Spacing And Pressure
The choice of spacing between sprinklers is associated closely
with both the application rate and the amount of pressure at the
nozzle. The primary factor which affects the choice of spacing is
the vegetative cover--open field crops or forests. An 80 by 100
foot spacing is preferred for open fields and a 60 by 80 foot spacing
is recommended for wooded areas. These spacings seem to give the
best relationship between good distribution and reasonable costs.
Rectangular, square, or triangular sprinkler patterns may be
used with solid-set distribution systems. Ordinarily some type of
triangular (or staggered rectangular) pattern permits the maximum
spacing between lateral lines which reduces installation costs. In
order to insure reasonable uniformity of application depth over the
area, the maximum spacing between sprinklers should not exceed 75
per cent of the effective sprinkler distribution diameter.
The frequency and intensity of wind affect the spacing of
sprinklers, the uniformity of application, and the preference of
nozzle pressure and size. As the spacing is increased, the height
of the spray stream must be increased according to the laws of
projectile motion. As the top of the spray stream arc becomes
higher the wind has a greater effect on the distribution pattern.
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Thus, windbreaks and border strips often become an integral part
of the irrigation distribution system design and must be considered
in the economic analysis.
The nozzle pressure and diameter are chosen such that the
appropriate rate of wastewater can be distributed unifoimly over
the specified area. For a specific hole size if the pressure is
too high, the water will mist and drift extensively. If the
pressure is too low, the emitting stream will not be adequately
broken and poor distribution again will result. The best advice is
to follow the manufacturers' recommendations of nozzle pressure-
diameter combinations.
While the above discussion of application rate, sprinkler
spacing, and nozzle operating pressure is appropriate for the
design of a solid-set irrigation system; it is not appropriate
for the designs of other irrigations systems as: the center pivot,
the giant gun, the traveling gun, and various other self-propelled
or hand moved systems. In open fields one of these systems may be
just as appropriate as the solid-set system and often may be more
economical. In most of central Pennsylvania, however, the geology,
topography, and tree cover encourage the use of solid-set systems.
Additional Factors
The physical features of the land, in addition to affecting
the sprinkler system variables, also affect the design and cost of
the entire system. The total head requirement for the system is
directly dependent upon the difference in elevation between the
pumping plant and distribution areas; as well as the friction loss
in the transmission and distribution lines, and the pressure
requirements of the sprinkler heads.
Design for a rough, undulating terrain, of course, is more
complicated than for a gentle sloping area because of static head
changes and more importantly the need for draining all lines during
periods of freezing conditions. The rougher the terrain the more
difficult this becomes. In areas with complex slopes the laterals
may need to be placed on supports to provide the uniform grade
required for rapid drainage. The number of drain locations should
be kept to a minimum to reduce labor and to peraiit more efficient
management.
The configuration of the distribution area frequently is
determined by the availability of land. Inefficient distribution
system arrangements involving greater costs often are required due
to unavailability of large, concentrated, gently sloping areas
having appropriate soil and geological conditions.
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Fanners ordinarily irrigate the best soils or fields on their
faims. The same should be true for canneries, industries, and
municipalities when irrigating their effluents. Unfortunately, too
many make the sad choice of acquiring the cheapest land available
which often is too wet, is too steep, or has insufficient soil depth
to provide adequate renovation.
In the choice of materials, one should remember that dissolved
chemicals in the effluent may cause corrosion or electro-chemical
deterioration. This deterioration may occur for 12 months each year
when irrigating liquid wastes, compared to 1 to 2 months for typical
agricultural irrigation. The chemical strength of the wastes,
expecially animal and certain cannery or industrial wastes, may be
many times that of typical agricultural irrigation water.
Laws and regulations concerning liquid wastes frequently
restrict design flexibility. The Departments of Public Health in
many states do not permit sewage effluent irrigation of crops used
for human consumption; with this most people agree. Some also do
not permit the irrigation of golf courses. Since regulatory
requirements differ from state to state it is essential to find out
what their design "suggestions" are as early as possible because
they can greatly influence a system design.
Some regulatory agencies arbitrarily "suggest" maximum sprinkler
diameters of coverage or minimum specific borders beyond ordinary
sprinkler wetting diameters. Unfortunately these suggestions too
often become required criteria on a check list, rather than the
beginning points for design consideration.
MANAGEMENT DECISIONS
Management of the system will be the deciding factor between
success and failure for many wastewater renovation facilities using
the living filter approach. Adequate size and flexibility frequently
are designed into the system, especially with the aid of state and
federal money. Unfortunately, in the hope of saving operational
money, systems too often are poorly managed.
Many new concepts and often completely new orientations are
required when managing irrigation systems for liquid waste disposal.
Whereas farmers now ordinarily manage for crop requirements, in
liquid waste irrigation one needs to manage for adequate renovation,
and the crop must be secondary. This indicates that usually the
municipality or company producing the liquid waste should own the
land and not the farmer. No matter how conscientious a farmer is,
it will be difficult to convince him to irrigate a crop which already
has received twice as much rain as necessary. In wastewater disposal
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management one applies maximum amounts of water to the land, not
minimum amounts. Most of the research and experience with irriga-
tion to date, however, has been with minimum amounts.
Monitoring of the effluent which leaves the renovation area
is an essential part of system management. Both surface and sub-
surface water discharge should be monitored in each dominant
direction of water egress. Monitoring facilities usually assay
only the quality of the discharge from the renovation area. Under
proper management, however, quantity also should be considered.
Costs always play a major role in management decisions,
especially in determining the amount of original capital outlay
relative to the amount that will be required for labor to operate
the system. Sewage effluent irrigation systems may be designed to
operate from 6 to 12 months per year and for seven days a week.
With that many hours of operation, hand moved systems usually cannot
be justified. But, can a city afford to pay $2,000 to $4,000 per
acre for a buried distribution system?
Traveler or center pivot irrigation systems may be used to
reduce the capital costs. These types of distribution equipment
may be secured for $150 to $500 per acre. The center pivot type
systems have both capital and labor-saving advantages if the topog-
raphy, field size and shape, lack of trees and streams, etc. are
conducive to their use. Traveler-systems flexibility under
adverse field conditions, but require more labor and may cause wind
drift nuisance.
As one compares the management decisions between agricultural
and liquid waste irrigation, he should ponder seriously the following
facts. In agricultural irrigation an individual farmer usually buys
the system; he operates this system with a wealth of background and
ingenuity; he works with his own equipment; he irrigates his best
land; he decides when to irrigate and when not, what crops and soils
to irrigate, and how much; and he makes all of his own decisions and
legally has the right to do so.
In liquid waste irrigation top level personnel of a munici-
pality, a company, or a corporation usually are responsible for the
management policy, however, someone far down the chain of command
frequently makes the day to day operational decisions. Management
policy generally provides for meeting federal or state agency
regulations. The employee making the specific system operational
decisions, however, all too often is not aware of the requirements
which must be met or of the consequences of improper choices.
When one chooses to irrigate year-round in areas where
temperatures drop appreciably below zero there are many additional
management decisions that must be made. In addition to the
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management of the sprinkler disposal system one must also assure
that no pollution results from irrigation on frozen soil. Pump-
ing, pipe system, and sprinkler head problems associated with
irrigation during times of below-freezing temperatures have been
previously reported by Myers (1966).
Management is the key to irrigation of effluent becoming a
significant tool for the conservation of nutrients and renovated
water, and for the elimination of much pollution in our present
water bodies. Proper management of the crops and of the irrigation
rates and amounts can produce the biological balance required.
When astute management of soils is added to the above, adequate
hydrological balance can also be attained.
ACKNOWLEDGEMENT
Research reported here is part of the program of the Waste
Water Renovation and Conservation Project of the Institute for
Research on Land and Water Resources, and Hatch Projects No. 1481
and 1809 of the Agricultural Experiment Station, The Pennsylvania
State University, University Park, Pennsylvania. Portions of this
research were supported by funds from Demonstration Project Grant
WPD 95-01 received initially from the Division of Water Supply and
Pollution Control of the Department of Health, Education, and
Welfare and subsequently from the Federal Water Pollution Control
Administration, Department of the Interior. Partial support was
also provided by the Office of Water Resources Research, USDI, as
authorized under the Water Resources Research Act of 1964, Public
Law 88-379.
REFERENCES
Myers, Earl A. 1966. Engineering problems in year-round distri-
bution of waste water, Proc. National Symp. on Animal
Waste Management, ASAE Publication No. SP-0366, pp. 38-41.
Parizek, R. R. and Myers, E. A. 1968. Recharge of ground water
from renovated sewage effluent by spray irrigation, Proc. of
the Fourth Amer. Water Resources Conf., New York, New York,
pp. 426-443.
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COST OF SPRAY IRRIGATION FOR WASTE WATER RENOVATION
John B. Nesbitt
Department of Civil Engineering
The Pennsylvania State University
The net cost of effluent disposal by spray irrigation is de-
pendent upon the system required to do a specific job, at a specific
location, at a specific time, as well as the procedures adopted for
management of the spray field. Since different situations require
different designs and management procedures, no general overall
cost information can be given. However, if certain basic assumptions
are made about design and management a rough cost estimate can be
made and that will be done here.
The figures presented are based on work done by Allender (1972).
He presented a procedure, supported by many charts and nomographs
which can be used as computational aids, which will enable an engineer
to make a preliminary design and cost estimate of a wastewater
renovation system using spray irrigation. Using the work of Al-
lender (1972), the estimated cost of hypothetical systems carrying
flows of one, five and ten million gallons per day (mgd) will be
presented. The figures are based on certain assumptions regarding
design and management. These assumptions may or may not fit another
specific situation but they will define the basis of the subsequent
estimates. They will be discussed under the general areas of
pumping system, delivery system, and operation.
PUMPING SYSTEM
It is assumed that the system will be pumping completely treated
(secondary treatment) municipal wastewater as this is the type of
effluent on which the Penn State study was based. Since wastewater
flows will be variable and pumping rates more or less constant, I
have assumed some sort of equalizing storage will be needed and have
chosen a pond designed like an oxidation pond with a forty-day
detention time. The detention time was selected on the basis of flow
records from several Pennsylvania communities. Other designs which
use longer storage or eliminate the storage entirely are possible.
The pumping station is a typical wastewater station with
the usual stand-by pimps and discharging into a force main. Also
included is a fine screen (not a microstrainer) before the pump
station to reduce clogging of the sprinkler nozzles.
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DELIVERY SYSTEM
In this discussion the delivery system includes the trans-
mission pipeline (force main) and the spray field itself with its
land, piping, sprinkler heads, and fittings. Costs for a monitoring
system are not included.
The estimates include the purchase of land at $140 per acre.
As this cost can vary from zero to well over $1,000 an acre, the
render can make the proper adjustment when the final figures
are presented. The amount of land required is based on a total
application of 2 inches per week at an application rate of 1/6 inch
per hour. The land is in open fields.
The sprinkler system uses solid set aluminum piping with 140
foot effective distribution diameter sprinkler heads placed in a
rectangular spacing of 98 ft by 70 ft.
The force main is one mile long with a 200 ft elevation lift.
This distance is probably short for many larger installations, but
may be quite appropriate for the small system where this process
may have its widest application.
OPERATION
Operation of the system assumes that the municipality must
provide its own sprayfield which is capable of receiving the entire
flow. While it is realized that this water can be of great benefit
to private agricultural lands, it is felt that continuous, un-
interrupted disposal on these private lands would not be possible.
On this basis, sale of effluent to owners adjacent to the trans-
mission pipeline would be a definite possibility. Calculations on
the returns available from this sale indicated at best it would be
an insignificant fraction of the total cost and it has not been
included in these estimates.
The crop for these estimates is Reed canarygrass. While the full
market potential for this crop has not yet been developed, its use
is sufficiently great that a rough estimate of the returns through
its sale could be estimated. Alternatively, the cost for its dis-
posal in a sanitary landfill is also estimated.
ESTIMATED SYSTEM COSTS
Now that the basis of design has been established the estimated
costs for flows of one, five, and ten million gallons per day (mgd)
are shown on Table 1 in 1967 dollars. You will note that capital cost
varies from $439,220 for a one mgd system to $2,431,280 for a ten
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Table 1. Estimated Costs for a Spray Irrigation System Q967
Dollars)
Flow-MGD
Item 1 5 10
Capital Cost
Distribution system $ 66,020 $ 336,700 $ 675,380
Lagoon 123,000 350,000 600,000
Pumping station,
screens 84,000 179,000 258,500
One mile pipeline 71,500 132,000 195,000
Land, survey, site 44,000 219,000 440,000
Engineering and con-
tingencies 50,700 152,100 262,400
Total $439,220 $1,369,500 $2,431,280
Annual Cost
.Amortization (20 yr
§ 6%) 36,750 111,100 197,800
Labor 1,900 1,900 1,900
Power (A), distribu-
tion system 2,200 10,800 21,600
Power (B), pump ef-
fluent 1 mile and
200 feet in eleva-
tion 2,310 11,740 21,260
Maintenance and con-
tingencies 3,410 11,500 20,500
Total $ 46,570 $ 146,840 $ 263,060
mgd system. Annual cost also shown on Table 1 includes amortization
of the capital cost in 20 years at 6% interest and ranges from
$46,570 to $263,060 for the one and ten mgd flows. Labor would be
by-personnel also used for other work and is considered constant
in this flow range.
The distribution of costs among the various system components
can be determined from Table 1. It can be seen that the capital
costs are nearly equally distributed among the system components.
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It is popular these days to present annual wastewater treatment
costs in terms of cents per thousand gallons of wastewater treated.
Annual cost on this basis is presented in Figure 1. The solid line
is constructed from the data in Table 1. The dashed lines now
include estijnates of the annual cost for sale or landfill disposal
of the Reed canarygrass crop.
The cost shown in Figure 1 compares favorably with other waste-
water treatment costs. With complete treatment cost at 15 cents
per thousand gallons for a 15 mgd plant, sprinkler irrigation would
add about 50 percent to the total treatment costs. Chemical treat-
ment for phosphorus removal is generally estimated at about 5 cents
per thousand gallons, and tertiary treatment by filtration and
activated carbon at 20 cents. Remember, however, that the sprinkler
irrigation cost used for comparison is for a one-mile pipeline to
the sprayfield.
Since the cost for wastewater treatment will always revert to
the individual homeowner, Figure 2 has been prepared to show the
cost on this basis. The transformation from Figure 1 to Figure 2
is based on an average household of 3.5 people at 100 gallons per
capita per day- In comparing costs obtained from this graph with
a typical municipal sewer bill, remember that the sewer bill
contains costs for both collection and treatment and that the costs
presented here consider only a one-mile transmission pipeline.
REFERENCES
Allender, Gerald C. 1972. The cost of a spray irrigation system
for the renovation of treated municipal wastewater, Master of
Science Thesis, Department of Civil Engineering, The Pennsylvania
State University, University Park, Pa.
312
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18
16
V)
o
g!2
10
fc
»
i
o
.£ 8
•85
5
« 6
_ \
2
0
Landfill Disposal of Crop
No Crop Disposal or Sale
<#•
Sale of Crop
4 6
Flow-MGD
8
10
Figure 1. Cost of Spray Irrigation Per Thousand Gallons. Esti-
mated Cost includes a 1-mile Pipeline plus a 200-foot
Elevation Lift.
313
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d
ui
18
16
14
- \
\
o
c
1 8
O
4
« I
\
Sale of Crop
468
Flow-MGD
10
Figure 2. Cost of Spray Irrigation Per Equivalent Dwelling Unit
(E.D.U.)- Estimated Cost includes a 1-mile Pipeline
plus a 200-foot Elevation Lift.
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FINANCING MUNICIPAL WASTE WATER TREATMENT FACILITIES
INCLUDING LAND UTILIZATION SYSTEMS '
Belford L. Seabrook
Division of Municipal Waste Water Programs
Environmental Protection Agency
Today, the number of sewered communities in the United
States is just over 16,000, serving 68 percent of the Nation's
population. During the next five-year period, we estimate that
about 8,000 of these communities will construct new, upgraded,
or expanded waste water treatment facilities.
This construction is needed primarily to meet established
water use goals for the receiving waters. However, a continuing
need for pollution abatement facilities will always exist after
standards have been achieved to compensate for a growing population,
obsolescence, and industrial expansion. Accomplishing this goal
will require dedication at all levels of government and will most
certainly require the cooperation of industry.
The Environmental Protection Agency is not approaching
industry nor anyone else as an adversary. Water pollution is not
just an industry problem or a government problem; it is society's
problem. We approach everyone as a partner, convinced that environ-
mental protection is everyone's job and everyone's responsibility.
We know that our waters cannot cleaned up tomorrow, that they
cannot be restored easily or without great effort and expense.
But we are determined to make a beginning.
From now on "pay-as-you-go" will increasingly be required for
insuring against the risks of manipulating nature. This means
that provision must be made for the protection and rehabilitation
of the environment before, or at the time, these resources are
used. The cost of maintaining the environment must be included
in the cost of doing business.
GENERAL ACCOUNTING OFFICE STUDIES
The General Accounting Office (GAO) submitted reports on the
construction grant program to the Congress in November, 1969, and
May, 1970. The reports discussed the effectiveness of the program
and the awarding of grants to municipalities in cases which benefit
industrial users.
The November, 1969, report pointed out that the suspension of
the dollar-limitation clause on grant awards in 1966 provided the
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initiative for the growing trend toward the treatment of industrial
wastes in joint municipal-industrial plants. The report indicated
that, should the trend continue, it could result in many of these
industry-associated costs for treatment facilities becoming eli-
gible for Federal assistance. In other words, the volume and cost
of treatment facilities receiving Federal financial assistance
would increase significantly. In short, the taxpayer would be
subsidizing industrial wastewater treatment with no control on
the quantity of waste products discharged into the system.
The later GAO report, dated May 8, 1970, called direct attention
to the fact that some grants were being awarded for the treatment
of industrial wastes only.
RECENT FEDERAL REGULATIONS
On July 2, 1970, Regulations were promulgated on treatment
works design, operation and maintenance, planning requirements, and
treatment of industrial wastes in municipal systems. The Regula-
tions provide for investment of the anticipated massive amounts
of public monies in a more coordinated and effective manner. In
addition to responding to criticism from the General Accounting
Office, the Regulations provide a solid base from which to achieve
the Agency goals of cost-effectiveness in planning, design, and
operation of treatment works.
INDUSTRIAL WASTE COST RECOVERY GUIDELINES
Federal guidelines for equitable recovery of costs for in-
dustrial waste treatment in municipal systems were issued in
October, 1971, to interpret the July 2, 1970, Regulation.
A system of "cost recovery" is to be provided by the grantee
wherever industrial wastes are to be treated by a facility built
with Federal aid. A municipality must assess industry's share of
the operating and capital cost of the community treatment facility.
Under present policy, industry's share will be in proportion to the
total costs of waste treatment for operation and maintenance,
and in proportion to the grantee's costs for capital costs. Thus,
the industry is not required to reimburse the municipality or
the Federal Government for the grant portion which will provide
facilities for treatment of industrial wastes. Pre-treatment must
also be provided by industry for wastes that would otherwise be
detrimental to the municipal treatment facility and collection
system.
However, the legislation now pending in Congress would require
recovery of the grant portion from industrial users. I will
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discuss this in more detail later.
The guidelines are designed to clarify the general provisions
and the criteria of acceptable compliance. The intent of the
guidelines is to define the minimum acceptable revenue to be de-
rived from industry for its share of the facility costs. The
emphasis is on the necessity for use of average cost pricing for
industrial users and all other users, based on the contributed
loadings, in terms of both quality and quantity of wastes.
Although EPA will approve any system that satisfied the intent of
the Regulations, the guidelines will serve to facilitate the
deteimination of compliance with the cost recovery requirements.
The primary Agency interests with respect to the intent of the
Regulation, therefore, are:
1. To implement the Agency's basic principle of imposing
the cost of waste treatment directly upon the source
of pollution;
2. To encourage the use of user charges based upon
volume and character of the wastes;
3. To promote equity in terms of improved knowledge
and acceptance by the system's users of the necessity
of paying for waste treatment and control;
4. To encourage reduction of waste strength through in-
plant control and recycling of by-products; and
5. to promote local self-sufficiency.
In order for the Agency to determine compliance with an
equitable cost recovery system, the grant application must furnish
complete information on existing treatment works and the proposed
expansion or modification including:
1. General information about industries located and served
(or to be served) by the treatment system;
2. Treatment works capacity, in terms of hydraulic and
BOD loadings;
3. Total excess capacity reserved for industrial waste
contributors;
4. Methods of financing for capital improvements including
amount and amortization schedule;
5. Methods for financing the operation and maintenance
317
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costs including special costs created by industrial
wastes;
6. Distribution of the revenues to be collected among
classes of users; and
/
7. Method of collection of revenues.
This then represents the administrative arrangements that were
developed to assure equitable allocation of wastewater treatment
costs among all users.
A survey is currently being conducted of certain representa-
tive existing wastewater land utilization systems throughout the
country to collect facts and experiences for the purpose, among
others, of evaluating these facts to form the basis for developing
Federal guidelines on land application techniques. Hopefully, this
information will become available to the public early in 1973.
With the caveat that the wastewater land application survey report
and the Federal Guidelines can be published in early 1973, planning
is currently underway to organize and hold the First EPA National
Symposium on Waste Water Land Utilization Techniques, to be held
in mid-1973.
OMNIBUS CLEAN WATER BILLS
President Nixon sent a significant number of proposals, re-
presenting his water pollution control legislation program, to the
92nd Congress during the first session. A number of proposals have
also been submitted by various members of Congress. Late in the
1st session the Senate passed, by an overwhelming vote of 86-0,
S. 2770 in lieu of the President's legislative proposals and certain
other bills. In the meantime, H. R. 11896 was introduced in the
House of Representatives. Hearings were held and the Bill was
passed by the House March 29, 1972, by a vote of 378 to 14. The
versions approved by the Senate and the House provide for a number of
substantial changes. Among the most significant are the following:
1. Both versions provide for the application of the
best practicable waste treatment technology after
June 30, 1974, following examination of all possible
alternatives. The Administrator is directed (in
Section 304 (d) (2)) to publish within 9 months after
enactment information on alternative waste treatment
techniques and systems available to implement Section
201 of the Act.
2. The Senate Bill authorizes a maximum Federal share of
70 percent. The House version would authorize a
maximum of 75 percent. The Joint Conference Committee
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(in June 72) adopted the 75 percent maximum and added
the provision that there would be no requirement for
matching State grants.
3. The House Bill would make certain sewage collection
systems eligible for Federal grants. The Senate Bill
does not contain this provision. Both versions,
however, provide for separation and treatment of
storm water.
4. Under the Senate Bill, the Administrator of EPA is
authorized to advance to a municipality up to 5 per-
cent of the estimated reasonable construction cost
of a project, after reviewing the engineering feasi-
bility report, to enable municipalities to complete
plans and specifications. Such funds need not be
returned in the event no further grants are made on
the project. The House Bill contains no provisions
for such advances.
5. Both the Senate and House versions provide for a
charge to be assessed on all users to assure that
each class of users pays its share of the cost of
operation and maintenance, including replacement of
sewage treatment works.
6. Both the House and Senate Bills require that munici-
palities levy charges on all industrial users to
recover the portion of the total capital cost covered
by both the local share and the Federal share, alloc-
able to the industrial load portion of the plant
capacity.
7. The Senate Bill provides that the Federal share re-
covered from industrial users of Federally assisted
municipal plants be received by the Administrator
and deposited in the United States Treasury. The
House version provides for the recovered funds to
stay with the local wastewater treatment management
agency to provide for replacements and other
plant needs.
8. The Senate Bill authorizes a total of $14 billion
from Fiscal Year 1972 through Fiscal Year 1975 as
the Federal share of the construction costs of munici-
pal sewage treatment facilities. The House version
will make available a total of $20 billion for sewage
treatment construction for the same period. The
Joint Conference Committee (in June 72) adopted the
House figure of $20 billion.
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9. Both bills pro-vide for the development of regional
waste treatment management systems.
10. Both bills require that guidelines and regulations
be published on pre-treatment of industrial wastes
prior to discharge to publicly-owned systems. This
applies to pollutants which interfere with, pass
through, or are otherwise incompatible with treat-
ment systems. Provision is also made for monitoring
of industrial discharges.
At this point it is not possible to predict the final outcome
of the proposed legislation with regard to cost recovery for treat-
ment of industrial wastes. However, it is significant that both
bills contain similar provisions for recovery of the grant portion
for industrial waste treatment.
The House Bill provides that grant funds cannot only be
utilized for the construction of land application facilities, but
such funds can additionally be utilized for site acquisition,
including farmland and forest land. The Joint Conference Com-
mittee, which is currently considering the pending legislation has
yet to resolve this matter.
The reference above, concerning alternative techniques and
systems, applies to land treatment and land utilization systems
that are an integral part of municipal wastewater facilities.
Construction grants can be made to cover the eligible costs under
the current program.
The following criteria will be helpful in evaluating waste-
water land utilization techniques:
1. Type of wastewater
(a) Raw sewage
(b) Primary treated sewage
(c) Secondary treated sewage
(d) Liquid digested sludge
2. End use of wastewater
(a) Disposal
(b) Agriculture
(c) Industrial reuse
(d) Recharge of aquifer
3. Esthetic attitudes of community
4. Availability of suitable land
(a) Ownership
(b) Leasing
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(c) Green belts
(d) Highway median strips
(e) Golf courses
(f) Farmland/ranchland
5. Length of operating experience
6. Social costs, including relocation assistance and
eviction costs
7. Institutional restraints
8. Public health factors
9. Build up of mineral and heavy metals in the soil
10. Odor and fly problems
11. Long-term problems
(a) No discharge a fallacy
(b) Runoff
(c) Sources of water supply
The particular technique and design of a land utilization
system for wastewater and liquid digested sludge will depend on
the situation and circumstances at each specific project.
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LARGE WASTEWATER IRRIGATION SYSTEMS: MUSKEGON COUNTY,
MICHIGAN AND CHICAGO METROPOLITAN REGION
W. J. Bauer and D. E. Matsche
Bauer Engineering, Inc.
The substance of this paper is directed primarily toward a
discussion of the costs and benefits of large land treatment
systems, using the experience with the Muskegon County, Michigan
system now under construction and the work done to date on pre-
liminary planning for a system to serve the Chicago metropolitan
region. These two projects will be described briefly, then the
cost experience and cost estimates for the various components of
the system will be analyzed. The division of the costs into
functional components is intended to facilitate the use of these
figures by others in analyzing, in a preliminary fashion, the
cost of a land treatment system in some other locality where the
relative costs of the components may not be the same as those
experienced in the Muskegon County project. The selected com-
ponents for cost analyses are:
1. Collection and transmission.
2. Pretreatment.
3. Irrigation.
4. Drainage.
5. Sludge handling.
6. Return and reuse of treated water.
7. Land acquisition.
In addition to analysis of both.the capital and operating
costs of these components, potential sources of income from the
wastewater irrigation system are evaluated. These are:
1. Agricultural production.
2. Long-term land values.
3. Leasing of space for electric power station.
4. Sale of cooling make-up water.
5. Sale of industrial process water.
6. Leasing of space for solid waste handling.
7. Recreational uses during non-irrigation seasons.
MUSKEGON COUNTY, MICHIGAN SYSTEM
This land treatment system is located in parts of Muskegon
County, Michigan on sandy soils common to that portion of
Michigan lying along Lake Michigan. Muskegon County is located
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approximately opposite Milwaukee, Wisconsin, roughly opposite the
midpoint of Lake Michigan. The wastewater management system is
physically divided into two parts: a larger portion serving the
more heavily urbanized area surrounding Muskegon Lake and Mona
Lake; and a smaller portion serving the less urbanized area around
White Lake. All of these lakes are large dune-impounded lakes with
outlets to Lake Michigan. The purpose of the project is to elimi-
nate the discharge of polluting materials into Lake Michigan from
which the water supply for most of the population of Muskegon
County is obtained. The population to be served is estimated to
be approximately 160,000 persons when the system is fully developed.
The design average flows for the fully developed system are esti-
mated to be about 43 mgd, with a peak capacity of roughly 90 mgd
which can be sustained for a relatively long time without adversely
affecting the final effluent quality. Of this total design flow,
about 40% is expected to be industrial and the remainder is
expected to be domestic wastewater. Initially, the industrial
portion comprises more than half of the total flow, because many
of the collecting sewer systems have not been constructed. The
largest single industry served is a paper mill with a design
average flow of 12 to 16 mgd of wastewater containing waste paper
and pulp fibre, plus some waste clay filler.
The larger of the two irrigation sites is an area of about 15
square miles located about K) miles east of the more heavily
urbanized area. It is underlain by medium sand ranging in thick-
ness from a minimum of 20 feet to a typical maximum of 60 feet.
There are also areas where the sand thickness is greater than 60
feet. The surficial sand deposits are underlain by an impermeable
clay layer which effectively prevents the vertical movement of
groundwater. Aerated lagoons with a design average residence time
of 3 days are used to provide the biological treatment. The normal
procedure to be followed will result in discharging the biological-
ly treated wastewater and associated solids into one of two 850-
acre storage lagoons. These storage lagoons provide additional
treatment and winter storage of the treated wastewater by being
allowed to fluctuate 9 feet in depth. A separate 8 acre settling
lagoon will be provided for operating flexibility to allow the
bypassing of the storage lagoons and permit the direct irrigation
of clarified effluent from the aerated lagoon system.
Percolation through the bottom of the storage lagoon is
controlled by intercepting ditches around the lagoons from which
it can be pumped either back into the storage lagoon, or to the
outlet drainage system, or to the irrigation system. Pumping
directly to the outlet drainage system is anticipated only during
the initial operations of the system, which will occur before all
of the irrigation system is ready to operate.
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The flow into the major irrigation system would then come from
either the storage lagoons or from the ditch which intercepts leak-
age from the storage lagoons. In either case, it is planned to
chlorinate it to provide a desired reduction in coliform count.
During the flow in the long open channels leading to the two
irrigation pumping stations, the excess chlorine will be dissipated
to prevent adverse effects in the soil. The two irrigation pumping
stations are each set up in two parts so that a total of four
separate irrigation systems may be served. Together these systems
utilize about 55 irrigation rigs of the pivot type, each of which
irrigates a circular area. These circular areas range in size from
about 40 to 160 acres. A total of approximately 6000 acres of land
are thus irrigated. The design application of irrigation water is
about 7.5 feet per year, or 2.5 million gallons per acre per year.
A total of 15,000 million gallons of water are thus planned to be
irrigated in the design year, or an average flow of 41.3 mgd. The
remainder of the design flow (1.3 mgd) is handled at the smaller
site serving the White Lake area. During the irrigation period of
roughly 30 weeks per year the average rate of application would be
3 inches per week. However, maximum rates of 4 inches per week are
anticipated during dry weather.
An extensive underdrainage system is provided in the Muskegon
County project, comprised primarily of drainage pipe systems which
discharge into drainage ditches. In addition, a smaller portion of
the irrigation site is drained by wells. Both pumping wells and
observation wells are provided. The purposes of the drainage system
are to prevent the saturation of the agricultural soils under the
most intense periods of irrigation and precipitation, and also to
control the direction of movement of the ground water around the
perimeter of the irrigation site. It was required by the Department
of Public Health that no out-migration of ground water occur.
Consequently, the design provides for a small inward migration of
ground water from the surrounding areas into the irrigation site.
Authorization to prepare construction plans and specifications
for the Muskegon County system was given in July of 1970; bids were
taken in May of 1971; bonds were sold to cover the $16 million
local share of the costs in August of 1971; and construction was
started in the fall of 1971. Construction has continued during
the winter of 71-72 with many of the collection system force mains
being completed by August 1972. The land acquisition program began
in October of 1971, and by March of 1972 about 85% of it had been
acquired without the use of condemnation procedures. Clearing of
the land began in April of 1972, and construction of the lagoons,
major drainage ditches, and other features of the irrigation site
were well under way in August of 1972. It is expected that the
initial operation of the system will take place late in 1972 or
early in 1973 with the collection, transmission, pretreatment and
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storage of a flow of somewhat less than 30 mgd. Leakage through
the bottom of the storage lagoon is expected to be rather large
until the sludge builds up a sealing layer over that portion of
the bottom which is not lined with clay. Design of the leakage
interception system is predicated on the assumption that leakage
will pass through a minimum of 500 feet of sand before being
intercepted by the perimeter ditch, and because the sand contains
large amounts of iron and other chemicals for the precipitation of
phosphate, the leakage water is expected to meet all of the
requirements for effluent from treatment plants discharging into
Lake Michigan. Therefore, the initial operation of the system
could occur without irrigation. The irrigation and drainage system
is expected to be completed during 1973, so that full scale operation
will take place during 1974.
The capital costs which are reported here are obtained from the
actual bidding for the component construction contracts of this
project. The operating costs are estimated from the calculation of
energy consumption, labor requirements, and maintenance procedures.
The estimate of potential revenues is based upon a forecast of the
auxiliary functions which are presently being contemplated at the
site, including the construction of a major nuclear power genera-
ting station.
CHICAGO METROPOLITAN REGION
A survey scope report for the U. S. Army Corps of Engineers
is being produced by the Chicago District on regional wastewater
management plans. The region to be served covers approximately
2500 square miles with a present population of about 7 million
persons in northern Illinois and northern Indiana. Domestic waste-
water, industrial wastewater, discharges from combined sewers,
discharge from storm sewers, and runoff from rural watersheds would
all be managed in this plan. Alternative treatment technologies,
ranging from activated sludge with advanced treatment processes
being added on, chemical/physical treatment systems with advanced
treatment processes being added on, and biological treatment in
lagoons followed by land treatment using irrigation and drainage
of agricultural areas are all being considered, both separately
and in various combinations. The goal of the study is to produce
a comprehensive basis for choosing the course of action to solve
the water pollution problems of the Chicago metropolitan region.
The cost estimates presented for this system are based upon a
layout of the physical elements of one of the systems being studied,
including several hundred miles of water conductors, 75 square miles
of lagoons, and 700 square miles of actual irrigation area. Further
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details of the layout of the project can be obtained from reports
by the Chief of Engineers issued in March of 1972, together with the
Technical .Appendix and the Cost Data Annex of that report.
The operating costs and estimates of potential revenues are
calculated on the same basis as those presented for the Muskegon
County project. The capital and operating costs are presented
without taking credit for any potential revenues from various
possible sources of income.
COST ANALYSES
Muskegon County Project
Collection and Transmission. The costs of the collection and
transmission systems for this" project are based upon the bids for the
following construction contracts:
Contract 10: 66-inch force main, 11 miles $ 4,502,025
Contract 11: Smaller force mains 1,230,930
Contract 12: Smaller force mains 841,309
Contract 13: Smaller force mains 1,135,400
Contract 15: Main pumping station, 90 mgd 1,565,000
Contract 16: Smaller pumping stations (7) 1,165,169
Total $10,437,833
It is significant that most of these costs would be incurred
regardless of the type of treatment used, as it is necessary to
convey the wastewater to the point of treatment. In the case of
Muskegon, the alternative treatment plant was located on a site
closer to the city, but all of the same pumping stations would have
been required. There would have been a shorter main line from the
main pumping station out to the site of the treatment plant.
To these costs should be added about 2 other small pumping
stations which were not advertised at the time of the general
bidding, plus a proportionate share of the engineering cost.; Add-
ing these gives a total of $11,500,000. Spreading this over the
rated average capacity of 43 mgd gives a unit capital cost of 27<£
per gpd average capacity. Spreading this over the rated peaking
capacity of 90 mgd gives a unit capital cost of 13<£ per gpd.
The operating cost of the collection and transmission system
is estimated as follows:
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Cost/Year
Smaller pimping stations, 5 § 3 mgd avg. flow
with a typical head of 60 feet, 50 hp avg. power
consumption at $75 per hp-yr $ 18,000
Service and maintenance labor for preceding 25,000
Intermediate pumping stations, 2 @ 15 mgd flow
with typical head of 60 feet, 150 hp. avg. power
consumption at $75 per hp-yr 22,500
Service and maintenance labor for preceding 20,000
Main pumping station, average of 41 mgd flow
with typical head of 180 feet, 1200 hp avg. power
consumption at $75 per hp-yr 90,000
Service and maintenance labor for preceding 30,000
Total $205,500
Dividing by 15,000 million gallons per year pumped, this amounts
to an operating cost of about $14 per million gallons.
Summarizing the collection and transmission cost of the
Muskegon County System we have the following:
Capital cost $11.5 million 27$ per gpd
Operating cost $ 0.205 million/yr. $14 per mg
Pretreatment. The pretreatment of the wastewater prior to the
irrigation involves biological treatment in aerated lagoons, bio-
logical treatment of effluent and digestion of sludge in stabili-
zation lagoons, and chlorination of the effluent prior to discharge
into the irrigation canals leading to the irrigation pumping
stations. The capital cost of the construction items involved in
this portion of the project are as follows:
Contract 18: (as awarded) $7,044,298
Clay lining 664,020
Soil cement placement 525,000
Cement for soil cement 381,000
Total $8,614,298
This is a cost of 20.6$ per gpd capacity, exclusive of the
sludge handling equipment.
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The sludge handling equipment would consist of a dredge and
pipeline, plus centrifuge to obtain a higher per cent solids, plus
several plows to place the sludge into the earth and cover it.
The capital cost of these items is estimated to be $500,000 or
1.2<£/gpd. The total capital cost for pretreatment is then 21.8£
per gpd. Operating cost of the pretreatment system is estimated as
follows:
Electric energy consumption of the mixers and
blowers, installed capacity of 2000. kw, with
an average load of 1200 kw at $100/kw-yr.
Electric energy consumption -lighting, and
miscellaneous small motors around the control
building and chlorination buildings.
Chlorine consumption for chlorinating the
treated effluent prior to irrigation @ 5<£/lb.
Sludge processing and pumping costs, 300 hp.
at $100 per hp-yr.
Laboratory and treatment process personnel,
including personnel for the taking of water
quality samples at wells and points of
discharge from the system, 10 persons.
Sludge disposal personnel, including 2 on the
dredge, 2 at the centrifuge, and 2 on the plow.
Total operating cost of pretreatment
$120,000/yr
10,000/yr
50,000/yr
30,000/yr
150,000/yr
90,000/yr
$450,000/yr
Summarizing the costs of pretreatment:
Capital cost (including engineering) $ 10,0 million 23^/gpd
Operating cost $450,000/yr = $30/mg
These pretreatment costs include the equivalent of secondary
treatment of the effluent, and the utilization of the sludge for
soil enrichment purposes.
Irrigation. Capital costs of the irrigation system include the
following construction contracts:
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Contract 1:
Contract 6:
Contract 8:
Contract 17:
Contract 22:
Clearing $1,500,000
Pressure piping 2,194,615
Electric power distribution 475,193
Irrigation pumping stations 500,000
Pivot Irrigation Rigs for 6,000 acres 1,500,000
6,169,808
600,192
$6,770,000
Sub-Total
Total Engineering
Total
Cost per gpd capacity (avg
Operating cost of the irrigation system may be estimated as follows:
Electric energy consumption, actually consumed
over a 7 -month period but averaged over the
year at the equivalent of 2000 kw @ $100/kw-yr $ 200,000
Operating labor, 10 men 150,000
Allowance for replacement of mechanical equipment
and other miscellaneous expenses 50,000
Total operating cost $ 400,000
Cost per mg $ 27.00
Drainage System.
estimated as follows:
The capital costs of the drainage system are
Contract 2: Agricultural drainage pipe
Contract 3: Main drainage pipe
Contract 4: Highway culvert
Contract 5: Main drainage channels
Contract 9: Well drainage control system
Subtotal
Engineering allowance
Total
Cost per gpd
$ 565,053
1,970,616
84,144
1,104,977
226,332
$3,951,122
348,878
$4,300,000
10*
Operating cost of the drainage system is relatively small, as
the pumping stations involved are very low head and the maintenance
personnel are the same ones as for the irrigation system. We shall
ignor the operating cost of the drainage system, as it is included
in the irrigation system for all practical purposes.
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Return and Reuse of the Treated Water. In the case of the
Muskegon County project, all of this cost is included in the cost
of the drainage system as the treated water is simply returned to
the waterways and drains naturally, ultimately into Lake Michigan
where it becomes available once again as water supply.
Land Acquisition. Assembly of the two project sites totaling
10,000 acres required the acquisition of 410 parcels of property-
including 185 occupied residences. A program of relocation assist-
ance was provided consistent with the requirements of the Federal
Uniform Relocation Assistance Act. The costs of the land acquisi-
tion program were as follows:
Acquisition of land and structures $5,000,000
Relocation assistance 1,000,000
$6,000,000
Cost per gpd 14$
Summary of the Muskegon County Project
The following is a summary of the costs of the Muskegon County
project based on 43 mgd.
Capital Cost Operating Number of
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CHICAGO REGIONAL PLAN
The costs for the Chicago Regional Plan are given in Table 1
taken from the Technical Appendix to the report of the Office of
the Chief of Engineers, Department of the Army (1972). These costs
apply to a system with an average flow rate of 2376 mgd with a
peaking factor of 1.75.
Extracting the corresponding costs from Table 1, one may
construct the following tabular comparison:
Muskegon Chicago
Item County Region Ratio
Average flow rate, mgd 43 2376 55
Peaking flow rate, mgd 90 4152 46
Total capital cost, fmillions 40 2000 50
Collection and transmission, $/gpd.. 27$ 30$ 1.11
Pretreatment § storage, $/gpd 23 11 0.48
Irrigation system, $/gpd 16 7 0.58
Drainage system, $/gpd 10 8 0.80
Return and reuse system, $/gpd 0 12
Land acquisition 14 13
Subtotals 90$ 81$ 0.95
Interest during construction and
miscellaneous expenses 4 2 0.715
Subtotals 94 83 0.89
General administrative expense 1 jl 0.50
Totals (capital cost) 95 84 0.89
Operating cost, $/MG 82 106 1.325
The. relatively greater collection and transmission costs for the
Chicago Regional Plan arise from the 104 mile maximum transmission
distance as compared to a maximum distance of about 15 miles for the
MusKegon County Project. Likewise, the relatively greater pumping
head--1,100 feet versus 230 feet--for the Chicago project largely
accounts for the greater operating cost. However, there may be off-
setting revenues as discussed in a subsequent section.
The relatively smaller pretreatment and storage costs of the
Chicago Regional Plan arise from the much larger lagoons and the
resultant great reduction in the volume of earth-moving per million
gallons of storage volume.
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TABLE 1. Summary of Costs for the'Land Treatment Alternative for the Chicago Metropolitan
Area!/
Item
Cost
Capital Cost
Transmission facilities
Wastewater tunnel and pipelines
Reclaimed water tunnel
Wastewater pumping station
Reclaimed water pumping station
Land treatment site
Purchase
Family relocation
Clearing and site preparation
Irrigation system
Irrigation pumping station
Irrigation rigs
Pressure pipe and appurtenance
Drainage system
Drainage pumping station
Plastic drainage pipe
Sewer drainage pipe
$ 627,638,000
257,000,000
80,000,000
22,000,000
291,000,000
27,000,000
36,588,000
23,370,000
58,531,000
60,782,000
2,358,000
16,616,000
172,914,000
$ 986,638,000
$ 354,588,000
$ 142,683,000
$ 191,888,000
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TABLE 1. Continued
Item
Cost
Aerated lagoon system
Earthwork
Slope and roadway construction
Aerators and mixers
Inlet, outlet, flow distribution
and crossing structures
Storage lagoon system
Earthwork
Slope and roadway construction
Inlet, outlet § chlorination structures
Irrigation and drainage channel system
Excavation
Lining
Crossing, diversion § drop structures
Monitoring system
Observation wells
Electrical system
14,300,000
4,733,000
33,877,000
16,766,000
76,560,000
17,030,000
40,392,000
32,295,000
26,879,000
1,253,000
4,280,000
28,340,000
$ 69,676,000
$ 133,982,000
$ 60,427,000
$ 4,280,000
$ 28,340,000
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TABLE 1. Continued
Item
Cost
CM
CM
Sludge disposal facilities
Administration and regional lab buildings
Subtotal capital costs land treatment system
Operating and maintenance cost
Labor (includes 25% overhead)
Managerial and administration
Operating engineers, chemists
Mechanics, electricians
Field inspection, maintenance
Secretarial and janitorial
Power
Main wastewater pumping station
Reclaimed water pumping station
Aerated lagoons
Irrigation and drainage pumping stations
Irrigation rigs
Chemicals
23,300,000
3,565,000
910,000
2,550,000
3,430,000
5,650,000
850,000
33,800,000
7,890,000
9,235,000
6,650,000
1,200,000
2,900,000
$ 23,300,000
3,565,000
$2,000,000,000
$ 13,390,000
$ 58,775,000
$ 2,900,000
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TABLE 1. Continued
Item
Cost
o>
C/1
Maintenance and supplies
Pumping stations
Aerated lagoons
Chlorination facilities
Irrigation rigs
Transmission pipeline and tunnels
Misc. building and site maintenance and
supplies (incl. transportation)
Sludge disposal
Total operating and maintenance cost per year
Present worth for operating and maintenance
cost (1975-2025)
Present worth for capital replacement
costs (1975-2025)
Total present worth for the land treatment system
1,150,000
340,000
70,000
1,160,000
885,000
1,530,000
11,200,000
$ 3,605,000
$ 1,530,000
$ 11,200,000
$ 91,400,000
$1,255,000,000
60,140,000
$3,315,000,000
—'Department of the Army, Office of the Chief of Engineers. 1972. Regional wastewater
management systems for the Chicago Metropolitan Area, Summary Report and Tech. Appendix.
-------
The irrigation and drainage systems are more economical in the
Chicago Regional Plan because of the larger diameter irrigation
machines, and because of the thicker aquifer.
The return and reuse system of the Chicago Regional Plan is a
significant portion of the cost because of the distance of the farm
from the points of reuse.
SOURCES OF INCOME
There are a number of potential sources of income from operations
which can be accommodated at the land treatment site with little if
any interference with the wastewater renovation operations, plus some
that are incidental to the proper management of the system.
Agricultural Production
Crops produced on the farm can significantly reduce operating
costs. For example, each acre of irrigated land will treat 2.5
million gallons of water each year. If this acre nets $100 per year
in income -- not at all impossible with the substantial quantity
of water and fertilizer being applied -- this is an income of $40
per million gallons of water treated, a significant reduction in
net operating cost, representing about 40 percent of it.
Long-term Land Values
Included in the cost of the project is an area of about 200
acres of land for each 1 mgd average flow. This allows for the
irrigated land, the land occupied by lagoons, and the land used for
the consumption of the sludge as soil enrichment material. The
value of this land over the long term could be very significant,
particularly as it is in a large block. For example, assuming that
some day in the future there is invented a much less expensive and
even more effective method of wastewater treatment and renovation,
the land could remain largely open and available for some other
use. It would be completely equipped with irrigation and drainage
systems, permitting high intensity agricultural use, for example.
Assuming this to be the case, the cost recovery at some future date
could well be $1000 per acre. This would recover $200,000 per mgd
capacity or, roughly, 20% of the original cost of the project.
Electric Power Stations
Power generation capacity of about 4 kw per capita are forecast
for urban areas prior to the year 2000. Space of these stations
appears to be difficult to obtain, as there is a strong desire by
most persons not to live near one. Space provided by the \vastewater
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irrigation farm appears to offer the ideal solution, being near the
urban areas, furnishing great isolation from human residential
areas, furnishing plenty of make-up water for cooling, and in the
large storage lagoons offering a possible heat exchanger facility
which otherwise would have to be constructed by the electric utility.
Taking the design population of the Chicago region to be 10 million
persons, and taking the design average flow rate to be 3000 mgd, the
possible installed capacity per mgd of wastewater average flow rate
is 40,000 mw/300 mgd = 13 mw/mgd. It is realistic to charge a
rental rate of $3 per year per kilowatt of installed capacity --
this would be 1 percent of the capital cost of the facility -- which
would generate a revenue of roughly $40,000 per year per mgd, or
about $110 per million gallons treated. This is seen to more than
offset the total operating cost of the wastewater system, and is
thus a very important factor in considering the economics of alter-
native systems. (This rental would be in addition to tax payments
to local bodies.)
Sale of Cooling Water
Still another potential revenue comes from the sale of water
for making up the water evaporated by cooling processes. Assuming
13 mw per mgd of treatment capacity, and assuming 12 mgd of average
annual evaporation per 1000 mw of installed capacity, the amount of
water evaporated would be 0.156 mgd/mgd. At a price of $50 per
million gallons, this would be a revenue of $7.80 per million
gallons treated, say, 7% of the cost of treatment.
Sale of Industrial Process Water
Some industrial processes such as steel mills and paper mills,
could logically be located on the site of the wastewater treatment
system to make use of the partially treated water prior to irriga-
tion. Rental space to such industries, and sale of water to them,
could also produce a significant revenue. It is not estimated here,
as the amount would depend upon the individual circumstances.
Solid Waste Processing
There is plenty of space in the irrigation farm area to set up
a solid waste processing facility, and to construct land fills with
the residual material remaining from such processing. Assuming 1
ton of solid waste per capita per year, a design population of 10
million persons, and an average flow of 3000 mgd including industrial
and storm flows, there would be roughly 10 tons of solid waste per
million gallons of water treated. Assuming a revenue of $2 per ton
of solid waste processed, this would be a revenue of $20 per million
gallons of water treated, or about 20% of the operating cost. Again,
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the amount of potential revenue is significant to the reduction of
total costs to the citizen served.
During the non-irrigation season, the 6,000 acre Muskegon
irrigation area and the 2,000 acres of unused buffer area could
potentially be available for various kinds of recreational activi-
ties such as snow-mobiling, riding, hunting and hiking. The
storage lagoon surface area also provides a water habitat for various
water fowl and other species. In Michigan, the various wastewater
lagoon installations completed to date have significantly augmented
the water surface wildlife propagation areas.
The value of land treatment sites as a means of containing
urban sprawl and of maintaining agricultural areas is difficult to
evaluate with a dollar figure, but many would ascribe significant
value to this function.
SIWMARY
The capital and operating costs for the Muskegon County,
Michigan project and for the Chicago Regional Wastewater Plan have
been presented in a form useful for making comparisons with alter-
native systems. Auxiliary uses of the land irrigation site are
described briefly, and the approximate potential revenues from each
estimated. It is obvious that the operating costs of the system
would be largely if not entirely offset by using the same land
irrigation site for many other purposes in addition to that of
renovating the wastewater.
No discussion of the benefits of treating the wastewater to
drinking water standards is presented here, as these benefits would
be comparable for any other system which would achieve the same end
result. It has been assumed that the high standards achievable by
the land treatment process will be adopted by society as necessary,
and that the most economical means to achieve them will be sought.
With the possible incomes from other sources, the operating cost of
the land treatment system is obviously very low, probably much
lower than any other reasonable system of treatment, even ones with
far less effectiveness in renovating the water. It is therefore
our conclusion that the use of the land treatment system for large
metropolitan areas deserves careful evaluation of those responsible
for the planning and engineering of solutions to the present
problems of water pollution.
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ACKNOWLEDGMENT
The Muskegon County project has been financed in part with
federal funds from the Environmental Protection Agency under grant
number C261503, and also under grant number 11010 GFS for portions
of the project work which are of a research and developmental
nature. The contents of this paper do not necessarily reflect the
views and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
The Chicago regional wastewater management study is sponsored
by the Chicago District, Corps of Engineers, Department of the
Army. The official designation is the Chicago-South End of Lake
Michigan wastewater management study.
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DISCUSSION
Unknown: Would you explain that land acquisition? Is this private
large farm land or public land?
Bauer: Yes. In both of these cost estimates we assumed that the
land would be acquired from private owners by the agency
constructing the system. In the case of Muskegon County,
the county is acquiring the land. Most of the land was
acquired by direct negotiation. We did have an increase
in the cost of the land at Muskegon over the original cost
estimates. There are two reasons for that. One is that
I suppose that it just was not appraised properly in the
first place. We had an independent land appraiser who
gave us an estimate of 2^ million dollars as being the
acquisition price of all that land and we put it in our
cost estimate as 3.2 million. The land is presently about
85% or 901 acquired and projecting on the basis of what
has been spent so far, the total acquisition cost is
estimated at roughly 5 million at the present time. Now
that's 100% local cost. It's not shared by the Federal
and State 'Government. There is another cost, however,
that is shared by the Federal Government, in fact, it's
totally paid for by Federal funds. There was a law passed
during the time that the project was getting underway
which said that if Federal money was involved and people
were displaced on the land, they were to be compensated.
In addition to being compensated for their land, they were
to be paid for any other costs they may suffer because of
being forced to move. Such things as: additional interest
on new mortgages. If they had an old mortgage at a low
interest rate and now they have to buy a new place and
they have to pay a higher interest rate; if they have
moving expenses; maybe they couldn't find any property that
was suitable without paying a higher price than they got
for their old one and that kind of thing. Those payments
added up to roughly somewhat less than a million and that's
compensated for by the grant from the Federal Government.
So these land costs that I'm putting in here are the
acquisition costs plus the relocation costs.
Davis: For both Chicago and Muskegon how much of this land would
be used for farming or forest? You referred to using
parts of it for lagoons and for electric plants and so on.
Bauer: Generally about 85% of it is used for agriculture and 15%
of it would be used for the treatment facilities and
related access.
Unknown: What kind of authority do you deem sufficient for the
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boundary area to come in both Illinois and Indiana?
Bauer: That's a subject that's being studied by somebody else.
The Corps of Engineers has engaged a separate consulting
firm to study the jurisdictional and the institutional
constraints. There are a number of alternatives. One
that I'd like to see is a private environmental utility
and in that case I think it could be pretty well funded
privately. This private environmental utility would
enter into contracts with the various cities from which
waste water would be taken and would enter into contracts
with farm operators and into contracts with the power
companies that wanted facilities on the site. It would
simply provide an environmental function. It would
receive and process solid wastes and so forth. That's
one very neat way to do it. It would also provide a
very large tax base for the area in which the facility
would be located. Another way would be to have an
authority created that would go across state lines,
something like the TVA. I think there are a number of
ways it could be done.
Lyon: I have a question and I guess I'm going to take the
perogative of the panel chairman and ask the last
question. What degree of renovation do you expect to
get from the irrigation drainage portion of the system?
Bauer: We expect to meet drinking water quality standards and
then beyond that we're very interested in removing as
much phosphate as possible. We've taken samples of the
soil in the farm areas to try to make some assessment of
its potential for precipitating out the phosphates and
according to the analysis of about 30 samples that have
been made so far, in the Chicago region, the calculations
show that on the surface of the soil particles is a 10,000
year supply of iron and aluminum for precipitating phos-
phates. The estimated concentration is about .01 milli-
grams per liter. Our logic is based on the fact that this
is the background level which is observed in natural
streams that are fed by water which is percolating through
the soil. We've been saying that natural soils have in
the upper horizon a sizeable phosphate concentration.
They must have, otherwise, the plants wouldn't grow and
yet we don't see the soluble phosphates leak down into
the ground water and out into the river. We're saying
that it is because of the huge surplus of precipitation
capacity that exists in that soil. Now we're going to
put on more phosphates. We don't know how much we are
going to accelerate the use of this precipitation
capacity but after going through our analysis we still
think that the concentration will be down at that 0.01
milligram per liter level.
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IMPLEMENTING THE CHICAGO PRAIRIE PLAN
Frank Kudrna and George Kelly
The Metropolitan Sanitary District of Greater Chicago
The Metropolitan Sanitary District of Greater Chicago has been
involved in environmental protection since its creation by the
Illinois State Legislature over 80 years ago.
Collection, treatment, and recycle of all domestic and in-
dustrial waste is a day-to-day responsibility of the Metropolitan
Sanitary District. During its long and successful history, the
District has researched, investigated, and practiced numerous methods
of chemical and biological treatment. The results of this experience
have clearly indicated that the ultimate solution to today's
problem of environmental destruction must come through an under-
standing of the environment and its natural purifying cycles. The
Sanitary District has developed a program for the recycle and reuse
of sewerage solids, the by-products of the water reclamation
process. It is a far-reaching, environmentally sound program based
on nature and the natural purifying cycles. The Sanitary
District calls its concept, "The Prairie Plan."
The first implementation of "The Prairie Plan" is being car-
ried out on over 7,000 acres of land in Fulton County, Illinois.
The District is constructing, out of land lain barren by strip
mining, and environmentally safe recycle farm with integrated
monitoring, quality control provisions, and multiple-use facilities.
In 1967, the Board of Trustees of the Metropolitan Sanitary
District formally adopted the environmentally sound policy of
"Solids on Land." A concept for the beneficial recycle of sewerage
solids, a by-product previously considered a waste material. With
the adoption of this policy, the Board authorized an extensive
program of research and testing to develop a system for implementa-
tion of this policy. The resulting engineering reports, demonstra-
tion projects, and experimental farms have proven that the solid
material removed from the used water, once stabilized, can safely,
economically and productively be recycled to rebuild soil and sus-
tain agricultural growth as a fertilizer substitute.
The most significant demonstration project has been a co-
operative effort between the Sanitary District and the University
of Illinois Agronomy Department under the sponsorship of a Federal
research grant. This continuing project is being conducted at a
test farm at Elwood, Illinois, and is designed to monitor the
342.
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immediate and long term environmental effect resulting from the
use of solids, now called, "liquid fertilizer."
To demonstrate to the residents of communities outside of
its jurisdiction boundaries (Cook County) that liquid fertiliza-
tion is safe and non-objectionable, the District constructed at
least one demonstration project in each of its eight urbanized
service basins within and surrounding the Chicago Metropolitan
Area. The most significant of these is a working farm at the
Hanover Water Reclamation Plant which has, for the past five years,
utilized the liquid fertilizer within a successful farming operation.
In addition, liquid fertilizer has been applied to park grass-
lands, has generated topsoil on a landfill in Lake Michigan (North-
western University), and has generated growth on 37 acres of barren
silica sand (Ottawa, Illinois).
The result of the research work and demonstration projects
was a clear indication that liquid fertilizer could be safely,
economically, and beneficially returned to the soil. Once the small
scale programs had proven successful, the Sanitary District de-
veloped a concept for the large scale implementation of its re-
cycle program called, "The Prairie Plan."
The Prairie Plan was the methodology for the location and total
design development of the 30,000 usable acres of farmland needed
for the safe recycle of all wastewater solids generated within
the Sanitary District.
Simply stated, the Prairie Plan is a program that utilizes the
assimilative capacity of nature for the environmentally sound
assimilation of man's by-products. Based on a principle of water-
shed planning, it utilizes the ground as an immense, natural filter
and collection system. Utilizing a single watershed with known
physical characteristics as the basis for application, not only do
the soil and living plants act as a filter, but there is a natural
way to collect all of the filtered runoff at one point for
continuous monitoring and water quality control. The result
is a flowing stream which is clean, free from silt, and potentially
a valuable resource for recreational, commercial, and industrial
development.
The Metropolitan Sanitary District, after extensive land
investigation, purchased in December of 1970, a parcel of land of
approximately 7,000 acres in the northeastern portion of Fulton
County located in the upper reaches of the Spoon River Watershed,
approximately 200 miles southwest of Chicago.
The land was acquired with the complete knowledge and co-
operation of the Fulton County Board of Supervisors. The site,
a former strip mine, offered the unique opportunity to not only
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recycle liquid fertilizer but to reclaim mine spoil, thereby,
increasing the local tax structure.
This site, although a relatively small percent of the entire
Spoon River Watershed, is located on the headwaters to several
small creed sheds. Its northern boundary follows a natural ridge-
line and its eastern boundary is also the upper reaches of the
watershed. Its location within the watershed, together with the
disruption of existing drainage patterns due to the strip mining
operations, has resulted in a site that is basically self-contained
in terms of water flow. This condition allows a site plan to
be developed around the concept of complete water monitoring and
control, assuring environmental quality.
As a first step in the actual site development, an inventory
of the physical characteristcs of the land was completed. This
environmental survey included topographical mapping, boundary
mapping, surficial soil mapping, subsurface soil and bedrock
investigations, surface drainage investigation and delineation of
existing or potential floodplain areas.
The Board of Trustees of the Metropolitan Sanitary District,
working in cooperation with the Fulton County Board of Super-
visors, in order to assure optimum benefits from the development of
its Fulton County Project, brought together a Steering Committee
to provide input into the land use planning of its property.
The membership of this Steering Committee includes local
elected representatives, interested local citizens, agencies and
departments of the State of Illinois (Illinois Environmental Pro-
tection Agency, Department of Conservation, Department of Business
and Economic Development), the Soil Conservation Service, Univer-
sity of Illinois (Agronomy School and Extension Service), re-
presentatives of local educational institutions, as well as staff
personnel from the Sanitary District.
The goal of this Committee has, from the beginning, been
optimum use for the greatest public benefit; recognizing that al-
though the land in Fulton County was purchased for the primary pur-
pose of the Solids on Land Program, the needs of the local com-
munities could be introduced into the plans with compatible
secondary goals of recreation, conservation and natural science
education.
The initial land purchase was divided into three zones for
planning and development. The land use plan for each of the areas
was developed and reviewed under the general direction of the
Steering Committee prior to implementation. The result of this
action has been a land use policy that reflects the needs of both
the citizens of Cook and Fulton Counties.
344.
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The primary example of this multiple-use concept has been the
leasing of over 700 acres of lake and park land to the citizens
of Fulton County by the Metropolitan Sanitary District for the
annual fee of $1. This fishing, camping and recreational site
has become a well-known and highly utilized County resource.
The first objective of the Sanitary District was to quickly
implement a transportation contract and develop temporary holding
basins to provide relief for the increasing liquid fertilizer
production in the Chicago area. This relief was provided by the
construction of the first of three holding basins, a 2 million
cubic yard basin, costing $586,254. Then a three-year turnkey
transportation contract was negotiated involving the shipment of
4 barge loads of fertilizer daily (7500 wet tons), via the
Illinois River, 200 miles to Liverpool, Illinois. There, barge
docks and unloading facilities were constructed and the material is
pimped approximately 10-1/2 miles through a pipeline to the com-
pleted holding basins. The cost of the three-year transportation
contract that was required to be operational in 90 days was
$17,900,000.
Having solved its immediate problem, the Sanitary District
developed farm fields out of the mine spoils and constructed a
distribution system consisting of a dredge installed at the holding
basins which carried the liquid fertilizer to a distribution
header and pump station which then transports it via a series of
surface pipelines to mobile water winch vehicles which spray the
liquid fertilizer onto the farm fields. A total of 810 acres will
be put back into productive agricultural utilization by the end
of 1972. And by the end of 1973, over 3,000 acres will be for
productive agriculture.
To date, the total cost of construction contracts awarded in
the Fulton County area is over $22,000,000. At present, the
District has under design three additional grading contracts, as
well as their distribution piping and pumping facilities.
The overall project cost of the Fulton County Operation is
at present below the cost of other alternatives. The initial
landholdings represent approximately 201 of the ultimate land needed
for the recycle of all solids generated within the Sanitary
District. As additional lands are acquired, a pipeline from the
District will be constructed and the unit cost of the Fulton
County Program will be greatly reduced.
The Sanitary District, with its Prairie Plan Program, has
developed a way to actually realize the now popularized goals of
recycle and reuse. The program has, from its conception, received
very favorable local and national press. The District's work
continues to be well received at the local level and 3,500
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additional acres of land have been acquired as a result of this
acceptance.
The slurry pipeline, now being planned, which will transport
the liquid fertilizer from Chicago to Fulton County, is being thought
of as having a unique multi-use potential of its own. Its loca-
tion within a rapidly urbanizing region offers the possibility
of significant areas of permanent open space, innerconnected
with recreational trails, parks and facilities. The pipe is being
planned so as to be able to accept inputs along the route from
existing and projected urban developments, as well as having the
provision for top-off for potential-use areas.
The acquisition and development of 30,000 usable acres of
land within the framework of the Prairie Plan offers the possibility
for the development of new towns and cities utilizing the open
space, clean water and wastes assimilative capacities of the site.
The Prairie Plan, if developed to its full potential, could
initiate and provide direction in developing regional parameters for
physical economic development, could be the catalyst in the es-
tablishment of open-spaced areas, flood control, conservation and
recreational space; and provide a new agricultural economic base for
soil replenishment. It would become an integrated program for
pollution control that would close the loop from user back to
resource; converting society's discards into usable forms while
maintaining the natural ecological balance.
The overall success of the plan to date has been the direct
result of a thorough research and demonstration program and
direct cooperative planning with local governments and State
regulatory agencies.
The Prairie Plan is a project that is clearly both economically
and ecologically sound.
DISCUSSION
Larson: Do you plan to use the barging transportation system
permanently or do you view a pipeline in the future?
Kudrna: No. The economics are very clear. I think, that the
pipeline cost is far less than barging. This is an
interim measure because of the time table involved. To
get something started and the fact that we only had a
portion of our land, we went with the barging operation.
But, we foresee in the long term future a pipeline as the
most economical transportation method.
Unknown: Are you using the 1 to 1.5% dry weight per year applica-
tion rate? The amount that was mentioned yesterday, that
is 10 to 15 dry tons per acre?
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Kudrna: The loading rate of sludge that we are using and that has
been approved by the Illinois EPA for strip mine land is a
first year application of 75 dry tons per acre. This will
be reduced to 25 tons per acre in a period of 5 years as
the organic content builds up. For undistrubed land that
already has an organic content, the application rate begins
at 25 tons.
Unknown: Do you have some cost figures you can give us?
ludrna: The cost per ton for the initial operation is approximately
50 dollars a ton which is comparable to other processes.
However, of that cost per ton, 34 dollars are attributed
simply to transportation. That cost is going to be greatly
reduced with the pipeline in the long term solution. Right
now, it's either equal to or slightly less than other
alternative methods such as heat drying, incineration,
Zimpro. However, it will drop as we get into the long term
transportation system.
347
-------
MT. SUNAPEE STATE PARK, NEW HAMPSHIRE
SPRAY IRRIGATION PROJECT
Terrence P. Frost, R. E. Towne, and H. J. Turner
Water Supply and Pollution Control Commission
State of New Hampshire
The Sunapee State Park spray irrigation system in Newbury,
New Hampshire, distributes pretreated sewage to mountain slopes
forested with mixed hardwoods and scattered conifers interspersed
with an occasional apple tree indicating orchard or pastureland
abandoned a generation or more ago. Conifers tend to dominate
the lower part of the slope with the numbers of oaks and birches
increasing toward the upper levels. The system was planned and
designed around the Pennsylvania State University project (Parizek
et al., 1967).
The Sunapee system is unique in size, degree of slope sprayed,
seasonal character, relatively poor soils, high groundwater levels,
and atypical sewage quality.
Selection of the land application system was based on several
timely occurrences in addition to the Pennsylvania studies. The
Sunapee State Park sewage disposal system is tributary to Chandler
Brook which drains the mountainous ski-slope terrain into Lake
Sunapee slightly less than a mile downstream. In 1969 the state
legislature by statute upgraded the lake water quality classifica-
tion from Class B to Class A. In the words of New Hampshire
law "there shall be no discharge of any sewage or wastes into
waters of this classification." The A classification, therefore,
compelled some form of tertiary or advanced waste treatment technique
at the State Park to prevent all wastes, treated or otherwise,
from entry into Lake Sunapee. Hence, the selection of spray
irrigation techniques which we were eager to apply in New Hampshire
in anticipation of keeping the nutrients and other wastewater
constituents out of the surface waters and away from the ground-
water.
The popular demand for reclassification to A was based,
primarily on prestigious considerations and fear of phosphorus
from sewage sources and the resulting algae nuisances. Mats of
water felt (vaucheria spp.), unpleasant to barefooted bathers, until
controlled by the State, seriously interfered with water-based
recreation at the Chandler Cove beaches and shoals. The algae
nuisance was attributed in part to the treated, nutrient-bearing
sewage entering the lake from the Sunapee Mountain recreational
complex.
348
-------
The Sunapee scheme is small. The spray area covers about four
acres. The two holding ponds, originally designed as sewage
stabilization or oxidation ponds and constructed in 1961, are each
about one acre and located at the foot of the mountain. Influent
to these sewage lagoons is by gravity flow in thousand-gallon
increments pulled automatically from a siphon tank downstream and
in series with the two State Park septic tanks. These intermittent
siphoned flows provide velocities sufficient to keep the downgrade
pipeline clear.
The spray irrigation segment of the Sunapee system is
seasonal. Spraying takes place only in the summer for about six
weeks between the first of June and mid-July--long enough to draw
down the average depth of the two oxidation ponds from six to about
two feet. Withdrawal of the top two and half million gallons for
spray irrigation renews the ten-month storage volume. Natural
runoff is diverted around the storage ponds except during the spray
season by plugging one culvert and unplugging another. Prior to
land application the stabilization pond effluent was disinfected
and discharged annually each spring to the adjacent Chandler Brook
during snow melt and subsequent high runoff.
Winter sports enthusiasts, chiefly skiers, enjoy the Park
in winter, mid-December to mid-March. About 113,000 tickets are
sold each winter at Sunapee State Park. Summer tickets sold
average nearly 33,000 for each of the last three years, 1969-1971.
Nearly all of the summer tickets are for rides up the mountain
and back by gondola ski lift. The Park supervisor advised there
are probably as many non-ticket-buying picnickers using the Park
as there are lift-riders. The Park is little-used in late spring
and late fall.
DESCRIPTION OF THE SITE
Soils
The soils of the forested spray irrigation plot, according to
the united States Soil Conservation Service (Pilgrim, 1972) are
typical of thbse found in the low mountain areas of New England.
Granite stones are found both on the surface and within the soil.
Natural fertility is quite low and the soils are acid. The area is
dominated by well-drained soils with soil depth of more than four
feet. Stone piles in the area indicate that the soils were farmed
during earlier times.
Four distinct soils (Charlton, Millis, Norwell and Paxton) have
been identified on the area. All have developed in loamy glacial
till material derived principally from granite and mica schist rocks,
Paxton, the dominant soil of the area is characterized as follows:
349
-------
(1) A 3-inch forest floor surface layer of partially decom-
posed pine needles and deciduous leaf material;
(2) A subsoil layer extending to about 24 inches consisting of
dark brown, fine, sandy loam. Water moves at a moderate
rate through this layer;
(3) A distinct hardpan layer occurs at about 2 feet and extends
to depths greater than 4 feet. This hardpan layer is light
olive brown and of fine sandy-loam texture. Vertical
water movement is slow through this pan and most water
moves laterally down slope on the top of the pan.
Annual soil monitoring is being conducted by the Soil Con-
servation Service and the New Hampshire Agricultural Experiment
Station. Eight soil pits have been established on the area. Pits
are opened for soil sampling after the summer spray operation. Soil
samples are analyzed for changes in chemical properties.
A comparison of water quality of Sunapee holding pond effluent
(spray irrigant) with the quality of holding pond effluents (after
secondary treatment) reported by the Corps of Engineers, United
States Army, Cold Regions Research and Engineering Laboratory at
Hanover, New Hampshire (1972) is given in Table 1.
METHOD OF OPERATION
Oxidation pond effluent chlorinated at 5 milligrams per liter
was sprayed for about six weeks during June and July, 1971, onto
the somewhat hilly four-and-a-half acre wooded terrain with slopes
of 10 to 15 percent.
Spraying was accomplished via three spray lines covering about
1.5 acres each for a total coverage of 4.5 acres. Each of the three
spray lines averaged fourteen Rain Bird kicker-type spray heads
mounted on 2-foot high risers. Feeder lines ascending the slope
are four-inch diameter aluminum irrigation pipe. Lateral spray
lines are three-inch diameter conventional farm-type irrigation
pipe. Spray nozzles are spaced 50 feet apart. Laterals range from
600 to 700 feet in length. Piping is held in place by metal fence
posts. Initially, when laid loose on cement blocks the pipelines
rotated under pressure and caused misalignment of risers as well as
chronic uncouplings of main and lateral horizontal pipelines.
Distance between lateral lines is about 80 yards. All piping
is self-draining to the northernmost holding pond.
350
-------
Table 1. Comparison of Sunapee Holding Pond Effluent with a
Typical Secondary Treatment Plant Effluent
Typical
Composition*
Constituent Range
BOD
SS
NHs-N
N02-N
N03-N
P
Na
Cl
Ca++
Mg++
K+
LAS
pH
mg/1
2-25
3-50
0-10
2-13
7-13
4-14
40-100
40-100
1-40
1-10
7-10
5-10
6.5-7.5
Sunapee Composition
Low Mean High
12
25
0.1
0.01
0.16
0.7
6.2
11
5.8
3.45
5.3
0.1
7.0
mg/1
28
83
2.0
0.14
0.61
0.9
17.0
23
8.4
6.75
6.8
0.2
7.9
55
296
4.4
0.95
1.48
1.2
21.2
30
14.5
11.80
8.1
0.3
8.5
r*
Excerpted from Table 3-1, p. 36, Wastewater Management by
Disposal on the Land, Cold Regions Research and Engineering
Laboratory, Hanover, New Hampshire, February 1972.
Spray nozzles were of three different sizes, one size to each
of the three lines to compensate for elevation differences between
the lines. Circular coverage around each riser was about one
hundred feet in diameter. Nozzle pressures ranged from 40 to 60
pounds per square inch. Each line delivered approximately 100
gallons per minute during the fourteen hours it operated once each
week. Application rate amounted to 0.14 inch per hour, equivalent
to a total weekly application of about 2 inches.
Spraying was done Tuesday, Wednesday and Thursday. Automatic,
sequencing timers started opening a motorized valve at 6:00 a.m.
in the morning. The valve when half-open, energized one of two
pumps and the spraying began, continuing until 8:00 p.m. in the
evening.
The system is protected against breaks in couplings or piping
by use of a time-delay device which will shut off the valve and
stop the pump if pressure is not reached within four minutes of
starting time. This avoids flooding the pumps and the combination
pumphouse and chlorinator room. Both pumps are 15 horsepower,
351
-------
electrically driven with one hundred gallons per minute pumping
capacity against a 100-foot head. Pumps were alternated each week.
Configuration of the sprayed terrain is such that most, if not
all, of the runoff from the sprayed area will divert back to the
stabilization ponds for ultimate reapplication to the irrigation
area.
Four forest floor (duff) pan lysimeters were randomly instailed
within the spray area and two were placed as controls outside the
area, one at a higher and one at a lower elevation than the spray
area. Method of placement was to remove the upper 4 to 8 inches of
forest floor and soil with as little disturbance as possible, put the
duff pan in place, and replace the relatively undisturbed duff layer
and soil in the pan. Sterile polyethylene two-liter bottles left in
thirty-gallon, friction-top, galvanized, weatherproof cans sunk into
the ground down slope of the duff pans were used to collect water
samples. The lysimeters were designed and positioned to collect
precipitation and spray liquid so that the volume per unit area
could be estimated, and the collected percolate analyzed in the
laboratory.
A test pit about 3 feet wide by 7 feet long and 5 feet deep
was dug within the spray area with lysimeter pans staggered along
one wall at the 1-, 2-, 3-, and 4-foot depths and the pit covered
with a hinged 4 by 8 foot sheet of 5/8 inch marine plywood. The
pit was later abandoned due to high groundwater and doubt as to
ability to collect representative samples.
A standard rain gauge was located under the forest canopy near
the top of and within the spray area, and a second rain gauge was
placed outside the spray area in the-open near the holding ponds.
Rainfall at the site for 3 years of record, 1969-1971, averaged 37.6
inches. Rainfall for 30 years of record at the United States Weather
Service rain gauge at the Concord, New Hampshire airport, about 30
miles from the spray site, averaged 38.8 inches.
Three well-points were driven along the downstream periphery of
the slopes and used as test wells. These three test wells, driven
to the point of refusal, average about 11 feet in depth and are used
to assay groundwater quality on the downslope periphery of the spray
area between the irrigation plot and the holding ponds. In addition
seven downstream domestic wells and one public spring were routinely
sampled.
Two sampling stations were located on Chandler Brook bracketing
the spray area. Comparative water samples from water supply wells,
test wells, duff pans, holding pond influent and effluent, and the
brook were collected and analyzed weekly for the components listed
in the various tables. Sampling continued before, during, and after
the spray period.
352
-------
RESULTS
Preliminary analyses of the data indicate that spray irrigating
with pretreated sewage stabilization pond effluent at Sunapee State
Park in Newbury, New Hampshire has not resulted in any substantial
or discernible alteration in the composition of the groundwater in
the test wells, water from the drinking water wells, or down-
stream surface waters. Quality of the percolate water collected
from a lysimeter in the spray irrigated area is given in Table 2.
For comparison, the quality of the percolate water collected from
a lysimeter in the control area is given in Table 3. Condensed
analytical results from Test Well B are given in Table 4. Results,
unreported here, were similar for other test wells. Water quality
samples collected from Chandler Brook upstream of the project are
given in Table 5. For comparative purposes, Chandler Brook surface
water quality data collected downstream of the project is given
in Table 6. Groundwater quality in the Herbert Smith family
drinking water well is given in Table 7. No changes that are
positively attributable to the project appear in the water quality
data for the Smith water supply. There is a possibility that con-
sistently higher nitrate nitrogen results may, later in the study,
be attributed to the spray system. The Smith well is about 800
feet from the spray area and is the private water supply nearest
the project. Data was accumulated for four other well supplies
and one surface spring. None of these supplies exhibited discern-
ible water quality changes attributable to the spray operation.
The uptake or percentage removal of various constituents in
the irrigant by the 4 to 8 inches of forest floor materials in the
duff pan lysimeters is shown in Table 8.
CONCLUSION
The small, seasonal, atypical sewage spray irrigation system at
the Sunapee State Park in Newbury, New Hampshire appears to have
worked effectively to date to protect contiguous groundwater and
surface waters. Based on experience in New Hampshire and Pennsyl-
vania it is the opinion of the New Hampshire Water Supply and
Pollution Control Commission staff that the Sunapee system will
probably continue to operate effectively for a long and perhaps
indefinite period of time at the present mode of operation.
353
-------
Table 2. Quality of Percolate Water Collected from a Lysimeter
in the Spray Irrigated Area
Constituent
PO.-P
4
pH
Alkalinity
N(X,-N
2
NO.-N
3
Cl-
Ca++
K+
LAS
Mg++
Na
Time
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
Number of
Samples
12
5
15
15
5
28
15
5
28
13
5
24
15
5
28
13
5
22
14
5
27
15
5
.28
12
4
18
14
5
28
15
5
28
Range
mg/1
0.000 -
0.025 -
0.003 -
5.5
5.6
5.2
5
12
3
0.000 -
0.002 -
0.010 -
0.052 -
1.17 -
0.13 -
0.5
7.3
1.0
0.8
5.2
0.1
0.7
4.9
1.6
0.1
0.1
0.1
0.30 -
0.78 -
0.01 -
0.3
0.7
0.6
0.090
0.072
0.174
7.7
6.8
7.0
23
20
50
0.046
0.174
1.350
2.180
7.17
26.20
4.8
18.5
17.5
3.1
9.2
44.2
4.9
8.2
10.0
1.60
1.49
3.66
4.5
7.5
11.7
Mean
mg/1
0.033
0.050
0.030
6.6
6.3
6.2
13
17
15
0.014
0.075
0.291
0.860
3.62
7.26
2.0
12.3
3.0
2.6
6.8
14.5
3.6
6.4
5.8
0.1
0.1
0.1
0.70
1.12
1.50
1.6
4.2
2.1
354
-------
Table 3. Quality of Percolate Water Collected from a Lysmeter
in the Control Area
Constituent
Time
Number of
Samples
Range
mg/1
PCK-P
4
pH
Alkalinity
N09-N
2
NCL-N
3
Cl-
Ca++
K+
LAS
Mg++
Na
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
13
1
11
13
1
21
14
1
20
12
1
20
13
1
21
13
1
20
14
1
24
14
1
24
12
1
15
14
1
24
14
1
24
0.000
0.003
5.1
5.3
2
7
.001
.001
.089
.070
0.4
1.0
0.6
0.1
3.0
1.5
all
0.1
.46
.37
0.3
0.3
- 0.396
-
- 0.144
- 6.7
-
- 7.4
- 18
-
- 25
- .013
-
- .678
- .926
-
- 6.57
- 7.0
-
- 5.1
- 11.2
-
- 12.2
- 8.0
-
- 11.0
0.1
0>k
.2
- 3.20
- 1.68
- 9.3
- 1.5
Mean
mg/1
.058
.020
.028
6.1
6.1
6.4
12
20
15
.067
.002
.115
.494
.556
1.964
2.2
2.0
2.2
2.5
2.7
3.2
4.7
6.5
4.5
0.1
0.1
01
.1
1.01
0.62
0.94
1.8
0.8
0.8
355
-------
Table 4. Water Quality of Samples Collected from Test Well B
Constituent
P04-P
pH
Alkalinity
N02-N
N03-N
Cl-
Ca++
K+
LAS
Mg++
Na
MPN
Time
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
Number of
Samples
34
7
30
36
7
46
35
7
46
33
7
40
34
7
45
34
7
40
37
8
45
33
8
45
32
7
23
34
8
45
33
8
45
34
Range
mg/1
0.000 -
0.006 -
0.001 -
6.1
6.4
4.6
30
31
30
0.000 -
0.008 -
0.003 -
0.011 -
0.051 -
0.001 -
0.5
1.0
1.5
4.0
7.6
0.2
0.7
1.2
0.8
0.1
0.1
0.1
0.84 -
0.86 -
0.29 -
3.6
1.58 -
2.4
3
0.149
0.017
0.047
8.0
7.5
8.0
46
36
45
0.163
0.019
0.167
1.550
0.460
1.110
5.5
1.7
5.6
30.7
12.5
13.8
5.1
1.6
3.4
0.1
0.1
0.1
5.50
1.11
1.58
6.6
4.25
7.3
3
Mean
mg/1
0.018
0.012
0.012
7.2
7.0
7.0
38
34
35
0.003
0.011
0.040
0.191
0.218
0.151
2.2
1.3
2.8
10.4
8.5
4.8
1.9
1.5
1.5
0.06
0.1
0.1
1.63
0.99
0.61
4.9
3.71
3.5
3
356
-------
Table 5. Water Quality of Samples Collected from Chandler Brook
Upstream of the Spray Irrigation Project
Constituent
Number of
Time Samples
Range
mg/1
PO.-P
4
PH
Alkalinity
NCL-N
L
NO,-N
3
Cl-
Ca++
K+
LAS
Mg++
Na
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
18
7
27
20
7
41
20
7
41
20
7
40
20
7
41
20
7
40
20
7
41
20
7
41
17
6
20
20
7
41
20
7
40
0.003
0.012
0.001
6.2
6.2
4.6
7
18
6
0.002
0.001
0.001
0.076
0.080
0.010
4
10
1.0
3.6
6.8
0.50
0.5
0.4
0.4
0.1
0.1
0.1
0.61
0.14
0.37
4.0
2.1
3.3
- 0.032
- 0.162
- 0.165
- 6.9
- 7.2
- 7.2
- 20
- 28
- 60
- 0.012
- 0.078
- 0.715
- 1.34
- 0.259
- 2.450
- 175
- 21
- 610
- 19.0
- 12.8
- 33.0
- 3.1
- 1.0
2.8
- 0.1
- 0.1
0.1
- 1.68
- 1.73
- 4.60
- 103.0
- 11.7
- 27.0
Mean
mg/1
0.012
0.044
0.029
6.5
6.8
6.6
14
23
23
0.005
0.014
0.039
0.294
0.172
0.272
20
15
24
7.74
9.99
7.45
0.9
0.8
2*%
.0
0.1
0.1
04
.1
1.01
1.04
0.97
13.9
8.4
14.2
357
-------
Table 6. Water Quality of Samples Collected from Chandler Brook
Downstream of the Spray Irrigation Project
Constituent
P04-P
pH
Alkalinity
N02-N
N03-N
Cl-
Ca++
K+
LAS
Mg+4-
Na
Time
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
Number of
Samples
19
7
27
20
7
40
20
7
40
16
7
38
20
7
38
20
7
39
20
7
40
20
7
40
18
6
20
20
7
40
20
6
40
Range
mg/1
0.002 -
0.001 -
0.001 -
6.2
6.7
6.1
6
9
7
0.004 -
0.001 -
0.001 -
0.098 -
0.080 -
0.010 -
3
0
0
3.8
9.3
0.7
0.5
0.5
0.4
0.1
0.1
0.1
0.64 -
0.98 -
0.38
2.9
2.3
1.8
0.031
0.041
0.054
7.1
7.0
7.3
22
31
35
0.010
0.101
0.825
0.467
0.348
0.584
29
39
52
12.5
15.2
28.6
1.8
1.6
2.5
0.1
0.1
0.1
1.33
2.23
1.95
19.4
22.9
25.6
Mean
mg/1
0.012
0.019
0.014
6.7
6.8
6.6
15
23
20
0.007
0.019
0.043
0.192
0.239
0.180
18
27
21
8.1
12.8
10.8
0.9
1.2
1.2
0.1
0.1
0.1
1.05
1.66
1.19
10.6
12.4
15.1
358
-------
Table 7. Water Quality of Samples Collected from the Herbert
Smith Well about 800 Feet from the Spray Irrigation
Project
Constituent
Time
Number of
Samples Range
mg/1
P04-P
*T
pH
Alkalinity
NCL-N
2
NCv-N
3
Cl-
Ca++
K+
LAS
Mg++
o
Na
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
before
during
after
16
7
40
16
8
39
16
8
40
16
8
38
16
8
39
14
7
38
16
8
40
16
8
40
14
6
20
16
8
40
16
8
38
.011
.018
.001
6.0
6.2
6.0
7
12
2
.000
.001
.000
.007
.012
.000
0.0
0.0
0.0
3.4
5.0
0.5
0.3
0.3
0.2
0
.1
.1
0.01
0.48
0.40
2.0
0.8
0.9
- .042
- .057
.71
- 6.8
- 6.9
- 6.85
- 16
- 24
- 75
.012
- .017
- .113
- .096
- .184
.57
- 20.0
- 26.8
- 15.5
- 7.0
- 10.0
- 12.3
- 3.1
- 0.5
- 2.0
.1
.1
.1
- 6.80
- 1.00
- 1.80
- 14.8
- 4.5
- 8.3
Mean
mg/1
.026
.035
.080
6.3
6.6
6.4
13
18
17
.004
.004
.009
.043
.096
.116
1.8
4.6
1.4
5.5
6.2
5.3
0.8
0.4
0.6
.1
.1
.1
1.65
0.72
0.78
3.9
3.0
3 A
.2
359
-------
Table 8. Degree of Wastewater Reclamation by Upper Eight Inches
of Forest Floor and Soil
Constituent Percentage removal3 Average
Nitrite
Nitrate
Phosphate
Potassium
Sodium
Chloride
Magnesium
Detergent
Calcium
(N)
00
(P)
CK+)
CNa-0
(C1-)
(Mg++)
(LAS)
(Ca~)
47
0
92
0
46
0
0
50
0
- 94
- 46
- 98
- 32
- 92
- 81
- 54
- 100
- 80
71
16
95
15
68
34
24
87
44
values obtained from 4 duff pan lysimeters.
REFERENCES
Corps of Engineers. 1972. U.S. Army, Cold Regions Research and
Engineering Laboratory, Wastewater management by disposal on
land, Hanover, New Hampshire.
Parizek, R. R., L. T. Kardos, W. E. Sopper, E. A. Myers, D. E.
Davis, M. A. Farrell, and J. B. Nesbitt. 1967. Wastewater
renovation and conservation, Perm State Studies 23, The
Pennsylvania State University, University Park, Penna., 73 p.
Pilgrim, Sidney. 1972. Personal communication, United States
Conservation Service, Durham, New Hampshire.
DISCUSSION
Francke: Mr. Williams have you had an experience with plastic or
rubber lined ponds?
Williams: No. They're much too expensive for our clients. We've
used clay with varying success. With good workmanship
and good clay material we can get a good seal. We have
tried bentonite and sand and have not had good success.
We have tried sprayed-on asphalt and have not had good
360
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success with this either. We have found that soda ash
helps to seal a clay lined pond. The ponds that have
leaked have ultimately sealed up rather well. The
Michigan Dept. of Public Health does not encourage pond
systems leaking unless they're planned to leak. Now we
do have some that we have planned to leak. We have run
hydrogeological surveys and have determined the location
of the groundwater table. In these situations there
are no wells for domestic purposes down slope from the
ponds.
Rhindress: I'm glad that last question was asked. In case anybody
has any doubt, in Pennsylvania we do not like leaking
lagoons, period.
361
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UTILIZATION OF SPRAY IRRIGATION FOR WASTEWATER DISPOSAL
IN SMALL RESIDENTIAL DEVELOPMENTS
T. C. Williams
Williams and Works, Inc.
Williams § Works has designed sixteen pond and irrigation
wastewater treatment systems for various governmental units in
Michigan. Eleven of these are completed, and the other five will
be operational in 1974. The first pond and irrigation wastewater
system was that for the Village of Cassopolis which was constructed
in 1964. The Cassopolis system consisted of a series of ponds,
Pond No. 1 being an anaerobic cell, Pond No. 2 being a clay-lined
facultative pond, Pond No. 3 and Pond No. 4 being unsealed seepage
ponds which we anticipated would seal up and become facultative
ponds. We expected Ponds Nos. 3 and 4 to leak but not, in the
long run, to be able to handle the total influent hydraulic load,
and therefore, we provided a spray irrigation system of about five
acres on the tail-end of the system so that we would have a way of
disposing of any surplus water at the time that the ponds sealed.
As it turned out, our seepage ponds have been more than enough to
handle the total hydraulic loading and in consequence, we did not
have any experience with the spray irrigation system. It is
important, we find, to keep the seepage pond areas mowed and to
dose them intermittently. So even though this system has been in
operation for eight years, we do not have any operating data on the
spray irrigation part of the system. In addition to these various
pond and irrigation wastewater treatment systems, we have, during
the past ten years, designed more than twenty pond systems in which
treatment is followed by discharge of the treated wastewater to a
nearby water course on a semi-annual basis.
Over the years, we have used the words "lagoon" and "pond"
interchangeably. But due to the widespread news coverage given to
one of our western Michigan cities when they had odor problems with
a sludge lagoon, we have adopted the use of the word "pond" almost
exclusively for our purposes. But whether they are lagoons or ponds,
we have used one of the following designs for the systems we have
developed:
1. Two facultative ponds designed to operate either in
parallel or in series at the discretion of the operator. We are
writing in our operating manuals that these ponds should be oper-
ated in parallel during the winter and in series during the summer.
During the winter, very little biological activity takes place in
these ponds and it is important that the organic loading be dis-
tributed between the two to minimize odor problems in the spring
when biological activity resunes.
362
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2, A series of ponds, consisting of an anaerobic cell followed
by at least three facultative cells.
3. Mechanically aerated ponds, followed by holding ponds.
These artifically aerated ponds can be either surface aerated with
floating aerators or can be aerated with compressed air.
An advantage of using the first type is that facultative ponds
require a minimum of operational attention. The treatment is
accomplished by natural means using the sun and the wind. Also, we
have a heavy algae bloom during the irrigation season and as a
consequence, the nitrogen, phosphorus and other organics are, to
a large degree, bound up in the algae cells at the time of irriga-
tion. When properly loaded, these ponds are quite nuisance free.
The major disadvantage to this type of design, in Michigan at least,
is the result of our climate which limits the possible loading to a
maximum of 20 pounds of BOD per acre. This limitation increases
the land requirements, of course, to such an extent that in some
cases it is not economically feasible to pursue the development.
This is the most expensive pond system in terms of capital require-
ments but it is the least expensive in terms of operating costs.
The second method, the use of an anaerobic cell followed by
facultative ponds, is also a natural system. Significant phosphorus
and nitrogen reductions are achieved by the growth of different
biota in each pond. An added advantage is the fact that less land
is required than for facultative pond systems. When they are
properly designed and operated, these anaerobic-facultative systems
can also be nuisance free. However, there are instances when it is
not possible to control the unit loading on the anaerobic cell and
odor problems have resulted. As a part of an EPA sponsored research
project on irrigation of pond effluent at Belding, Michigan, data
has been collected for the past five months on the anaerobic-
facultative pond system. It shows a significant decrease in the
phosphorus and nitrogen through the pond system. It has also been
noted that while there is an abundance of phosphorus and nitrogen
in the last two ponds, there is not always a significant algae
bloom. The wastewater to be irrigated from this pond system is much
lower in nutrients than that from the activated sludge plant at
Penn State. The Belding system is a mature pond system. It has
been in operation since 1965 and, incidentally, it does take a
significant volume of combined storm and sanitary flow in addition
to the strictly sanitary flow from the community.
The third type of design involves the use of artificial
aeration and is used most frequently for larger communities because
the land requirements are less. The disadvantage is in the addi-
tional operating expense necessitated by increased maintenance
requirements and the purchase of electricity.
363
-------
One important consideration in each of the three types of
lagoon systems we have designed is the provision for a minimum of
five months storage of the wastewater. In our opinion there are
three major advantages of this provision:
1. The severe climate in Michigan presents special irrigation
problems during the winter. The storage of the wastewater avoids
these problems.
2. Operation costs for the treatment portion of the system
are substantially reduced as the storage pond can be depended upon
to provide a certain portion of the treatment.
3. The storage allows for the development of algae and
rotifers. To some extent, a prolific growth of these organisms
converts the soluble phosphorus and nitrogen into cells which is
of value in the irrigation process as the nutrients are applied to
the land in cellular rather than liquid form, and this allows for
a slower breakdown and absorption rate.
The selection of the best lagoon design for a particular client
should be made on the basis of site availability, economics and
operating experience. It is relatively easy to evaluate data
pertaining to sites and economics - engineers have been doing that
for centuries - but in the area of operating experience, we
encounter a severe shortage of data. There is a certain amount of
information about the irrigation of effluent from mechanical treat-
ment plants. Unfortunately, however, there are very few systems
involving the combination of ponds and irrigation in operation at
the present time - and these have been operating for such a short
time that there is only a limited amount of data available. At best,
we have only theory, guided by opinions.
The following data pertains to the operation and characteristics
of the pond system at Belding, Michigan, from March 15 through
July, 1972:
General characteristics of the influent:
NH--Nitrogen - 25 ppm
Total phosphorus - 2 to 12 ppm P, about 75% of which is
orthophosphate P pH - 7.2
D.O. - 0.0
364
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Pond water quality variations:
Pond 1: NH3-N - 20 ppm in April, 20-25 ppm in August
Pond 1 Pond 2 Pond 3 Pond 4. Pond 5
Apr. Aug.. Apr. Aug. Apr. Aug. Apr. Aug_. Apr. Aug.
NH3-N 20 25 20 5 20*0.5 20<0.5 20<0.5
N03-N <0.6 <0.6 <0.6 <0.25 <0.25
P 5- 10 5592 92 92
pH < -7.2 < varies considerably with photo -
reproduction
SS 4— 60 ppm with
great variation < < 20-25 >
DO ^—<0.1 highly vari-
able, max. highly variable
25+ but never 0.0
With respect to chemical and particulate changes Ponds 1 and 2
are- each uniquely different and Ponds 3, 4 and 5 are similar to each
other but different from 1 and 2. In general suspended solids (SS)
and concentration of living organisms are directly related. pH
values above 8.3 and dissolved oxygen (DO) above 10 ppm occur together
and are products of photosynthesis.
In Pond 1 during March through June decomposition of algae is
rapid in the anaerobic deeper waters and phosphorus is released as
rapidly as it becomes organic bound in the upper layer. Additional
phosphorus is solubilized in May as decay of older detritus becomes
significant. In July, Pond 1 "went bad" losing most of its aerated
upper water and living populations died and settled out.
In Pond 2 the living populations have their greatest range in
photosynthetic activity and population concentration resulting in a
more/stable total phosphorus concentration and occasional extremely
high DO values.
In Ponds 3, 4 and 5 as living populations and concomitant
populations of dead and settled organisms increased through March
and April, total phosphorus decreased. From mid-May through June
release of phosphorus by decomposition of dead organisms became
dominant. DO and pH responded to photosynthesis in all months but
were outstandingly volatile in July.
365
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The selection of the best land disposal method is only slightly
more scientific than the means available for determining the best
lagoon system. However, by the end of 1973, we anticipate having
better data on the various methods we have utilized. Basically, one
or more of the following methods are incorporated into the projects
we have designed:
a. Continuously loaded seepage basins.
b. Intermittently loaded seepage basins.
c. Intermittently loaded flood irrigation fields.
d. Portable aluminum pipe systems.
e. Solid set systems in which the pipes are buried.
f. Travelling sprinkler.
g. Center pivot sprinklers.
In selecting the proper land disposal method, consideration
must be given to soils, topography, climate, depth to groundwater
table, direction of movement of the groundwater table, chemistry of
the natural groundwater, proximity of wells tapping the groundwater
formation being recharged, and cropping.
In Michigan, it is common practice to chlorinate lagoon effluent
before spray irrigation. There is general agreement, however, that
chlorination is not necessary in flood irrigation or seepage basin
projects except in those instances in which the flood irrigation
area is underdrained. The lower power requirements and the avoid-
ance of chlorination costs have combined to make a substantial
argument in favor of flood irrigation and seepage methods (a, b, and
c). However, it is most difficult to achieve uniform distribution
of the nutrients over the entire site with these systems. If the
concept to be followed involved the reliance upon soil chemistry for
nutrient removal, the method of application is not as important.
If, however, the Penn State "Living Filter" concept of nutrient
removal by cropping is to be utilized, then spray irrigation is the
best method.
Tables 1 and 2 give design data on nine pond and spray irriga-
tion land disposal projects in Michigan. These vary in size from
6,000 to 900,000 gallons per day. Table 3 gives the construction
cost per capita. In the following table, these costs have been
grouped according to the size of the community:
366
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Table 1. Design Data for Several Spray Irrigation Systems in Michigan
ON
Project
Belding
Middleville
Ottawa Co.
Infirmary
East Jordan
Wayland
Harbor
Springs
Leoni Twp.
Design Future
Population Population
(year)
8,000
(1993)
2,200 3,200
(1990)
63 80
(1968)
3,700
(1990)
5,000
(1990)
5,000^
(1970)
9,000 25,000
(1975)
Design
Flow
gpd
800,000
150,000^
6,000
370,000
500,000
580,000^
900,000
Loading in
Ibs. BOD
per Day
1,360
374
16
440
850
7652/
1,530
Total
Retention
Tine
months
4
5
7
7
5
5
6
Total
Pond Area
acres
51.4
22.0
1.0
22.0
31.0
21.4
35.5
-------
Table 1. continued
oo
Project
Roscommon
Village
Cassopolis
Design Future
Population Population
(year)
1,550
(1990)
2,200
(1970)
Design
Flow
gpd
155,000
220,000
Loading in
Ibs. BOD
per Day
264
374
Total
Retention
Time
months
6
5.5
Total
Pond Area
acres
16.0
18.5
— .Approximate average measured flow over a 5-year period.
2/
—' Summer time - approximately 3 months.
-' Winter time - approximately 9 months.
—' 4,500 summer population; 2,500 winter population.
-' Includes 310,000 gpd infiltration.
-------
Table 2. Spray Irrigation .Application Rates for Several Spray Irrigation Systems in Michigan
o\
Proj ect
Belding
Middleville
Ottawa Co.
Infirmary
East Jordan
Wayland
Type of
Spray
Irrigation
solid set
solid set,
portable
laterals
portable
solid set,
portable
laterals
traveling,
center
pivot
Area of
Spray
Irrigation
acres
15.6
25.1
and
5.3
3.3
42.0
20.0
and
33.0
Instant Yearly
Application Application Application
Rate Rate Rate
(Period of
time)
in . /hr in . /hr inches
0.12 2.0
4.0
0.12 2.7-/ (7 mo.)
0.12 80^/
0.25 2 (3 mo.)
80
0.12 2.86 (7 mo.)
62
2.5 (7 mo.)
76
-------
Table 2. continued
Project
Harbor
Springs
Leoni Twp.
Roscommon
Village
Cassopolis
Type of
Spray
Irrigation
traveling,
center
pivot
solid set
solid set
solid set,
fixed
laterals
Area of
Spray
Irrigation
acres
30.0
and
21.3
140
24.0
8.0
Instant
.Application
Rate
in./hr
0.36
0.20
0.04
Application
Rate
in./hr
4.0
4.3
3.3
3.3
12.4
Yearly
Application
Rate
(Period of
time)
inches
(5 mo.)
88i/
(5 mo.)
95
(6 mo.)
86.3
(6 mo.)
86
(2.5 mo.)
346
— Different application rates on different crop areas; there are 5 different areas.
7.1
— The length of the irrigation period is being determined by tests - rest of the effluent will be
disposed of into the nearby river.
3/
— Used for future expansion.
—'Approx. (2) months of storage has to be disposed by other means.
-------
Table 3. Per Capita Costs for Several Spray Irrigation Systems in Michigan
Project
fielding
Middle vi lie
•Ottawa Co.
Infirmary
Acres of Land _ Cost of Ponds Cost of Spray Irrigation
Purchased r> ™ n n
Per Per Per Per
(Cost per Acre) Total Acre Capita Total Acre Capita
$257,200 $5,000 $32.20 $ 91,980 $5,100 $10.50
124.5 159,600 7,250 72.50 62,800 2,060 28.50
($350)
already owned I/ I/
the land
Total Treatment Cost
Per Capita
Total (not incl. Land)
$349,200 $ 42.70
260,650 118.35
32,800 520.00
East Jordan
used the air- 110,000 5,000 44.00 82,500 1,960 32.00 380,000 151.00
port property
-------
Table 3. continued
. Acres of Land Cost of Ponds Cost of Spray Irrigation Total Treatment Cost
Purchased per per per per Per Capita
(Cost per Acre) Total Acre Capita Total Acre Capita Total (not incl. Land)
Wayland
133 $165,000 $5,325 $33.00 $100,000 $1,890 $20.00 $365,000 $ 73.00
($500)
Harbor
w Springs - 198,000 9,300 39.80 75,900 1,480 15.15 849,700 170.00
NJ ,
Leoni Twp. - 526,500 14,200 58.50 1,138,500 126.50
Roscomnon
Village - 136,696 8,544 88.20 90,654 3,777 58.50 326,573 210.70
Cassopolis
40 83,855 4,540 38.20 20,000 1,080 9.10 140,355 63.80
($395)
I/ Package contract, no breakdown available.
-------
Population Design
Less than 2,000 - 2 Systems
2,001-8,000 -6 Systems
More than 8,000 - 1 System
Per Capita Cost
$212 to $520
$ 43 to $170
$126
Activated sludge treatment plants in Michigan towns between
3,000 and 12,000 population for the same time period, varied from
$77 to $274 per capita. Generally, in evaluating alternatives, we
find that a modified activated sludge treatment plant with chemical
precipitation results in the lowest first cost when we take into
consideration the land cost for land disposal schemes.
For the past several years in Michigan, grants have totalled
75$ of all eligible project costs. The State of Michigan provides
251 in addition to the 501 federal grants available. Since land
costs are not grant eligible, land disposal is the "high-priced
spread" if only the amount of the initial local bond issue is taken
into consideration. However, since all operating costs are also the
responsibility of the local community, it is important to give them
careful consideration in relation to the entire project. The follow-
ing table indicates the range of operating costs for various facilities
in Michigan. The activated sludge and trickling filter operating
costs include an allowance for the cost of removing 80% of the
phosphorus by chemical precipitation.
Community
City of Grand
Rapids
Treatment Provided Population
Activated Sludge
City of Ironwood Activated Sludge
City of Otsego Trickling Filter
Village of L'Anse Activated Sludge
Leoni Township
City of Belding
Aerated Lagoons
Followed by Spray
Irrigation
Anaerobic-Aerobic
Pond System
Followed by
Irrigation
fervedT
More than
300,000
9,000
4,000
Less than
3,000
9,000
5,000
Operation §
Maintenance
Cost Per Year
Fer Customer
$ 9.00
26.00
23.00
37.00
11.00 (Est.)
17.00
373
-------
Village of Anaerobic-Aerobic Less than Less than
Cassopolis Pond System with 3,000 $5.00 per
Seepage Lagoons year
Land disposal is not a panacea - it is merely another tool.
During the same period of time our firm has been developing lagoon-
irrigation projects, we have also been designing other types of
treatment such as extended aeration systems, rotating bio-disc
plants, aerated lagoons followed by chemical precipitation - and on
occasion, septic tanks and tile fields. Today, many noble efforts
are being expended toward the preservation of our environment, and
our water resources in particular. The world is eagerly awaiting the
discovery of the best method of treating and disposing of wastewater.
In our opinion, it is not good judgment to regard any one method as
the best. The dangerous implication in that label is that since "the
best" has been found, there is no need to continue to seek better
ways of doing the job. The search for better ways should be
unending. If no way is considered the best, each wastewater project
can be given individual consideration, the proper method can be
selected on the basis of professional engineering judgment rather
than emotion, and the search for a better way can continue.
374
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ECOLOGICAL AND PHYSIOLOGICAL IMPLICATIONS OF GREENBELT
IRRIGATION WITH RECLAIMED WATER
V. B. Youngner, W. D. Kesner and A. R. Berg, L. R. Green
Department of Plant Sciences Fire Research Laboratory
University of California Forest Service, USDA
Although Southern California is best known for its farmlands
and urban conmunities, millions of acres are covered with chaparral,
sage and woodlands. These wildlands are now largely confined to
the foothills and mountains but still extend from the bluffs above
the Pacific ocean to the desert (Jaeger and Smith, 1966). To
a great extent they remain in a primitive condition, but residential
and recreational developments reach into them from every direction
producing an intimate association between wilderness and human
activity creating numerous problems new to the region.
Southern California has many local climates determined by
elevation, proximity to the ocean and relationship to mountain
ranges. Nearly all, however, are basically Mediterranean char-
acterized by mild wet winters and long dry, generally warm, sum-
mers. Except for occasional brief thunderstorms, little rainfall
occurs from April to November (Bailey, 1966).
The native vegetation is well adapted to this climate as many
species become dormant or semi-dormant during the latter part of
the dry season. As the long drought continues, the shrubs that
make up the wildlands become increasingly dry and flammable. Hot
dry "Santa Ana" winds often occur in autumn making the fire
hazard extremely high.
Fires have been a part of the natural environment of the
chaparral for thousands of years, rejuvenating the brush and main-
taining a natural balance among shrubs, forbs, grasses and trees
(Vogl, 1967; Sweeney, 1967). With the first winter rains following
a fire many shrub and small tree species resprout from their
bases. The new open spaces once covered by dense brush are quickly
filled with shrub seedlings, grasses and other herbaceous plants.
However, today, because of the numerous settlements in these
wildlands such fires cause great loss of property and often of
human life and therefore are no longer acceptable. Fire control
is now a general but costly practice through the region. Not un-
expectedly fire control by permitting excessive build-up of
potential fuel has made fires that do occur many times more dan-
gerous and difficult to contain. Many studies are underway to
find new ways of handling the problem such as controlled burning,
375
-------
use of growth retardents and construction of fuel breaks.
Other problems are also created by the influx of people into
the wildlands. Water consumption is excessive in many places
causing a constant lowering of underground water reserves. To
conserve more of the water from rain and snow improvement of
watershed quality is imparative. Waste disposal facilities,
never really adequate, are falling further and further behind causing
a serious pollution problem. Nevertheless the demand for recreation-
al facilities such as campground and picnic areas by people from the
urban centers is unabated. Although restrictions on movement of
people into the wildlands has been considered and even attempted
a strong legal basis for this does not at present exist and the
destruction of a great scenic natural resource is everywhere
evident.
OBJECTIVES AND DESIGN OF PROJECT
In 1970 a research project designed to find a partial solution
to these problems was begun through a cooperative effort of the
university of California, the U.S. Forest Service and the California
Division of Forestry. Financing was obtained from the U.S.
Department of Interior, Office of Water Resources Research through
the University Water Resources Center and from other agencies
principally the San Bernardino County Flood Control District. The
objective is to study the feasibility of using wastewater from the
mountain communities to irrigate greenbelts of native and in-
troduced plants. The concept is that such greenbelts strategically
placed would reduce the wildfire hazard while disposing of waste-
water, recharging groundwater reservoirs with purified water,
and creating new manageable recreation areas.
Answers to numerous specific questions would determine the
practical value of the project. Foremost among these are the fol-
lowing: 1) What rates of water application can be safely used
on the rocky often shallow mountain soils? 2) What degree of
water purification can be achieved at the different rates of
application? 3) Can the moisture content of chaparral plants
be raised sufficiently to give them fire retardent qualities?
4) How will irrigation through the dry season affect the growth
of chaparral species? 5) What exotic trees, shrubs and grasses
will best meet the stated project objectives? 6) Will irrigation
change the species composition of the chaparral community?
The study area is located on a gently sloping chaparral cov-
ered ridge in the Maloney Canyon of the San Bernardino National
Forest (Goodin and Kesner, 1970). Although the elevation of the
project site is 4600 to 4700 feet, it is on the Mojave Desert
side of the mountains so the mean annual rainfall is only about
376
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25 inches and summer temperatures often reach 90°F. The soils are
shallow sandy loams over a granite or decomposed granite parent
material. Four distinct soil types have been mapped for the experi-
mental area.
Soil A
Soil A has a dark grayish brown cobbly sandy loam textured
surface soil which is slightly acid to neutral. The subsoil is
a dark grayish brown loam. This soil ranges in depth from 10 to
18 inches. The parent material is a highly weathered granodiorite
which can be augered to a depth of 50 inches or more. Five to
15 percent cobbles and stones are found on the surface of this
soil. Along the south end of plots 8-8, 10-2 and 12-2, 15 to
20 percent boulders and stones are found on the surface. Perme-
ability is moderate (2.50 to 5.0 in./hr), maximum water holding
capacity 5.5 to 7.5 inches and the erosion hazard is high on cleared
areas and moderate on undisturbed vegetated areas.
Soil B
Soil B has a grayish brown to dark grayish brown heavy
sandy loam having a slightly acid to neutral surface soil. The
subsoil (B horizon) is a light to dark yellowish brown and brown
medium to slightly acid sandy clay loam. Parent material is a
granodiorite that begins at a depth of 24 to 45 inches which can
be augered to a depth of five feet or more. Within the surface
horizon cobbles will range from 0 to 15 percent while on the surface
they will range from 15 to 25 percent with a few isolated areas
having as many as 50 percent. Permeability is moderately slow
(0.20 to 0.80 in./hr), maximum water holding capacity is 15 to
25 inches and the erosion hazard is high on the cleared plots and
moderate on the vegetative plots.
Soil C
Soil C has a grayish brown to dark grayish brown cobbly heavy
sandy loam slightly acid to neutral surface soil. The subsoil
(B horizon) is reddish yellow to brownish yellow medium acid to
neutral sandy clay loam. Parent rock is a granodiorite that
begins at a depth of 12 to 18 inches and easily augered to a depth
of five feet or more. Cobbles in the surface soil vary from 0
to 20 percent and from 0 to 25 on the surface with as much as 50
percent on isolated areas. Permeability is moderately slow
(0.20 to 0.80 in./hr), maximum-water holding capacity is about
8 to 10 inches and the erosion hazard is high on the cleared plots
and moderate on the vegetative plots.
377
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Soil D
Soil D has a brown to dark brown loam neutral reaction sur-
face soil. The subsoil (B horizons) is yellowish red, medium to
slightly acid clay loam. The parent material is highly weathered
granodiorite beginning at a depth of 25 to 35 inches which becomes
hard fresh rock within a few inches. Cobble percentages on the
surface and in the surface soil horizon ranges from 10 to 20
percent. Permeability is moderately slow (0.20 to 0.80 in./hr).
Maximum water holding capacity is 12 to 22 inches and erosion
hazard is high on the cleared plots and moderate on the vegeta-
tive plots.
The vegetation is typical desert chaparral. Ceanothus
(Ceanothus greggii, Gray and C. integerriumus H. and A.), flannel
bush (Fre¥pnyia' californica Torr.) and bigberry manzanita
(Arctostaphylos^ galuca LindT.) are the principal shrub species.
California Black Oak (Quercus keloggii, Newb.) and Coulter Pine
Pinus coulteri Don.) are scattered throughout the area. The under-
story ofvarious grasses and forbs is sparse under the heavy stands
of brush but quite dense where the brush is light.
The study area of 25 acres is divided intp 48 plots, 100 by
200 feet. Four irrigation treatments (0, 1, 2 and 3.5 inches
per week) are followed throughout the dry season. Within each
irrigation treatment there are blocks in which the native vegeta-
tion remains intact, others in which the native vegetation has
been cleared with subplots of introduced trees, shrubs, grasses
and forbs. All treatment plots are randomized and replicated three
times. Species planted on the cleared plots are shown in Table 1.
Water is applied through eight impact sprinkler heads on seven-
foot risers per plot. The entire system is automatically con-
trolled. Wastewater is obtained from the Arrowhead Village sewage
disposal system ponds located above the experimental area. The
sewage treatment facility provides primary and secondary treatment
and 2 ppm chlorination prior to discharge of the water into the
effluent ponds. Present discharges from this plant average over
750,000 gpd of which the experimental project uses only about
100,000 gpd. Since the wastewater is derived almost entirely from
domestic, non-industry, sources it is of relatively high quality
(Table 2). The analyses may be similar to that of most other
mountain resort communities in Southern California. Nitrates fluctu-
ate from almost none to a high of 64 ppm. Testing procedures follow
those of Standard Methods for the Examination of Water and Waste-
water and atomic absorption spectrophotometric methods.
378
-------
Table 1. Plant Species Introduced in Cleared Study Plots
Scientific Name
Common Name
Abies concolor
Pinus attenuata
Pinus Jeffrey!"
Pinus sylvestris
Pinus
_ om.be rg ii
Pseuclotsuga macrocarpa
Pseudotsuga Menziesii
Sequoia gigantea
Libo cedrus de curr ens
Pinus CouTteri
Pinus Lambertiana
Abies magnifica
Pinus pjonderosa
Agrostis palustris
Festuca ovina
Festuca rubra
Festuca rubra conmutata
Poa pratensis
Trifoliutn repens
Festuca arundinacea.
Oryzopsis miliacea
Ehrharta calycina
Phalaris tuberosa var.
Agropyron trichophorum
Agropyron intermedium
stenoptera
White Fir
Khobcone Pine
Jeffrey Pine
Scotch Pine
Japanese Black Pine
Big-cone Douglas Fir
Douglas Fir
Big tree
Incence Cedar
Coulter Pine
Sugar Pine
Red Fir
Ponderosa Pine
Pencross creeping bentgrass
Sheeps fescue
Red fescue
Chewings fescue
Fylking Kentucky bluegrass
White clover
Tall fescue
smilograss
veldtgrass
Hardinggrass
Pubescent wheatgrass
Intermediate wheatgrass
A complete weather station installed at the project site
provides a continuous record of temperature, humidity, precipita-
tion, wind velocity, wind direction, and evaporation. Soil moisture
is measured by electrical resistance blocks placed one, two and
four feet below the surface. Groundwater is sampled at various
depths by suction tubes (Youngner e_t al, 1971).
Specific vegetation studies as related to the irrigation
treatments include the following: 1) Transpiration of native
species as measured by a diffusion porometer (Van Bavel et al, 1965).
2) Photosynthesis of selected native species using the
14c02 method of Shimshi (1968). 3) Water potential of leaves
of selected species measured by the pressure bomb (Scholander
et al, 1964). 4) Increase in branch length of native species.
5T "Fuel moisture levels (moisture content of twigs and branches
379
-------
Table 2. Typical Analyses of Sewage Effluent during 1971-72
Ca (ppm)
Mg (ppm)
Na (ppm)
K (ppm)
NH4N (ppm)
S04 (ppm)
Cl (ppm)
NOsN (ppm)
K>A (ppm)
HC03 (ppm)
Conductivity
(EC x 10' 6)
PH
Hardness as
CaC03
Total dissolved
residue (180°C)
F (ppm)
B (ppm)
19
4
48
8
1
20
34
15
30
350
-
64
258
0.4
0.3
20
4
45
13
29
20
36
6
30
92
364
6.7
66
231
0.3
0.3
_
-
62
12
-
-
48
4
109
410
6.7
-
-
-
0.0
24
3
38
16
-
-
-
1
41.0
505
7.4
-
-
-
24
4
38
16
-
-
-
1
44
545
7.3
-
-
-
24
3
40
14
4
12
46
2
38
153
390
7.4
82
275
0.5
0.2
of selected sized). 6) Survival and growth (increase in height)
of introduced trees. 7) Biomass, percent cover and frequency of
various wild and introduced grasses and forbs.
OBSERVATIONS AND RESULTS
Results must be considered preliminary at this time since the
study has been underway less than two years. Nevertheless a number
of distinct trends are apparent.
Evaporation rates during the summer months in this area are
extremely high often exceeding 3 inches per week. Consequently
the low irrigation rate of one inch per week has had little effect
on vegetation growth, establishment of new plantings and replenish-
ment of fuel moisture. Apparently most of the water applied in
this treatment is lost through evaporation before it can penetrate
into the soil.
380
-------
The two higher irrigation rates have clearly influenced tree
establishment (Table 3). The highest application rate (four
Table 3. Percent Survival of Coniferous Trees One Year
After Planting
Species
Control
Weekly irrigation in inches
3.5
Scotch Pine
Japanese Black Pine
Khobcone Pine
White Fir
Ponderosa Pine
Incense Cedar
Jeffrey Pine
Sequoia
Coulter Pine
Big Cone Spruce
Douglas Fir
Red Fir
Sugar Pine
%
13.0
22.2
50.0
6.3
15.0
10.7
7.1
4.1
14.8
5.8
0.0
0.0
0.0
%
20.8
20.8
30.7
0.0
16.6
6.6
13.3
0.0
8.7
5.5
11.7
0.0
15.1
1
65.2
69.5
33.3
0.0
0.0
16.6
21.2
0.0
0.0
0.0
8.7
0.0
3.3
1
95.8
63.0
33.3
15.3
34.7
25.9
29.5
4.3
10.0
5.3
18.2
4.3
17.2
inches per week) has been especially beneficial but the medium rate
(two inches per week) has permitted satisfactory establishment of
only certain species. Establishment in the non-irrigated treatment
was limited to one block with the exception of Khobcone pine
which has some survivors in all three replications. This block
has the deeper finer textured soil with a higher water holding
capacity (Soil B). Variability among replications is perhaps
largely a result of differences in soil type.
Excellent stands of most introduced grass species have been
obtained under the high irrigation rate. Under the two lower
rates only the two wheat grasses Agropyron trichophorum and
A' intermedium and red fescue, Festuca ruEra, have developed
satisfactorily at this time.
On plots cleared of brush and irrigated but not planted to
other vegetation wild grasses are the most abundant species at the
present. The density of grass stand increases directly with the
irrigation rate. Yerba Santa, Eripdictypn trichocalyx, is also
abundant and is especially noticable on blocks receiving no water
381
-------
or only one inch per week. This is a small shrub, spreading by
rhizomes, common to burned over or disturbed areas of the chaparral.
Moisture content determinations of the chaparral plants in-
dicate that the two higher irrigation rates significantly increase
fuel moisture (Table 4). The low irrigation rate appears to be
insufficient to consistently maintain moisture levels above the
control. Moisture content differences among plants from the four
irrigation treatments are greatest in the smaller, generally
younger, twigs of 1/8 inch or less in diameter which have a higher
moisture content normally. Samples of this type from the non-
irrigated plots range in moisture content from about 55% to about
1221 of their dry weights at various seasons. Samples from the
highest irrigation treatment range in moisture content from about
95% to about 143% of their dry weights at these same times. Thus
a rather large elevation in fuel moisture content has been ac-
complished during the peak fire season when the brush is normally
very dry. This may be particularly important to fire control as it
occurs in fine twigs and leaves that may be most readily ignited.
Chaparral growth is increased by the effluent water irrigation
(Table 5). The increase in shoot length is to be a great extent
directly proportional to the amount of water provided. Increased
chaparral growth, of course, may not be desirable relative to the
fire hazard.
Soil moisture determinations in the irrigation treatments
support the vegetation studies. In general soils in the low ir-
rigation treatment do not contain significantly more water at
any depth than do those in the control treatment. Considerable
variability in soil moisture has been observed in the 2 and 3-1/2
inch per week irrigation treatments. This is not unexpected
considering the variation in depth, infiltration rate, and water
holding capacity among the four soil types present in the site.
Differences in the brush density and type would also influence
soil moisture. At this time it seems that only the 3-1/2 inch
per week application rate might be expected to significantly add
to the underground water reserves under the conditions of this
study.
As testing of subsoil moisture was started only in July
1972, data on water purification are still very meager. So far
water has been sampled to a maximum depth no greater than four
feet because of the rocky parent material encountered below that
level. Nevertheless samples from a four-foot depth in the high
irrigation plots show nearly 100 percent reduction of phosphates and
perhaps as much as 50 percent reduction of nitrates below that of
the effluent.
Our first tests for fecal coliform in the groundwater show no
colonies in 100 ml samples. Tests of the effluent water show
382
-------
Table 4. Moisture Content (percent of dry weight) of Ceanothus greggii Branches of Three Sizes
oo
as
Affected by Irrigation Treatments
Twig diameter in inches
0.25 or less 0.25 - 0.50 inch
Date Inches of water per week
0
1971
July 84.8
Aug. 62.7
Sept. 54.5
Nov. 61.5
1972
June 122.0
July 85.2
1 2 3.5
100.2 123.2 129.8
75.3 98.8 106.7
62.5 83.2 99.8
79.0 87.3 94.0
122.3 136.2 142.9
77.2 99.0 97.9
Inches of water per week
0 1 2 3.5
59.3 67.8 72.8 77.2
54.0 57.0 64.2 64.2
51.2 54.8 63.0 57.7
54.5 55.5 55.2 55.7
71.7 71.1 76.9 76.0
62.7 64.1 66.8 82.9
over 0.50 inch
Inches of water per week
0 1 2 3.5
54.5 59.8 64.3 71.8
47.0 45.5 58.2 61.8
49.0 47.3 59.2 57.5
_
57.4 57.8 62.3 63.2
51.7 56.8 54.5 61.4
-------
as much as 1,228 colonies per 100 ml.
Table 5. Mean Growth of Ceanothus greggii Branches as Affected
by Irrigation Treatments in 1972
Location of Branches
Irrigation
Treatment
Control
1 inch per week
2 inches per week
3.5 inches per week
Top
mm
49
92
146
152
North Side
mm
35
61
64
118
South Side
mm
60
51
87
143
CONCLUSION AND SUMMARY
Although no conclusive results have been obtained during the
short time this study has been underway observations to date are
sufficiently encouraging to make continued study highly worth-
while. Clearly, irrigation of chaparral during the dry season
will increase the moisture content of the wood and leaves.
The normal dormancy is apparently strictly draught induced and the
brush will readily take up water when it is provided regardless of
prevailing high temperature or species phenology. Future experi-
mentation must try to relate these results to degree of fire
retardation.
Conversion of chaparral brush lands to grasses and other plants
presenting a lower fire hazard appears possible through wastewater
irrigation. The most satisfactory species with particular
reference to the use of the irrigated areas for recreation must
still be determined.
Whether satisfactory water purification can be obtained through
the shallow mountain soils is still uncertain but preliminary data
are very encouraging.
REFERENCES
Bailey, H. P. 1966. The climate of Southern California. Univ. of
Calif. Press, Berkeley.
Goodin, J. R. and W. D. Kesner. 1970. First annual report of the
Moloney Canyon Project. Univ. of Calif. Water Resources Center
384
-------
33 p.
Jaeger, E. C. and A. C. Smith. 1966. Introduction to the natural
history of Southern California. Uhiv. of Calif. Press,
Berkeley.
Scholander, P. E., H. T. Hanmel, A. E. Heramingsen, and E. D. Brad-
street. 1964. Hydrostatic pressure and osmotic potential in
leaves of mangroves and some other plants. Proc. Nat. Acad.
Sci. 52, 118-125.
Shimshi, D. 1968. A rapid method for measuring photosynthesis
with labeled carbon dioxide. Jour. Expt. Bot. 20, 381-401.
Sweeney, J. R. 1967. Ecology of some "Fire Type" vegetation in
Northern California. Proc. Calif. Tall Timbers Fire Ecology
Conf. 7, 111-125.
Van Bavel, C. H., F. S. Makayoma, and W. L. Ehrler. 1965. Measuring
transpiration resistance of leaves. Plant Physiology 40,
535-540.
Vogl, R. J. 1967. Fire adaptations of some Southern California
plants. Proc. Calif. Tall Timbers Fire Ecology Conf. 7, 79-109.
Youngner, V. B., W. D. Kesner, A. R. Berg and L. R. Green. 1971.
Second annual report of the Maloney Canyon Greenbelt Pro-
ject. Univ. of Calif. Water Resources Center Contribution
No. 135, 22 p.
DISCUSSION
Dissmeyer: I understand in Southern California you've got some
water repellent soils due to the combination of vegeta-
tion and fire. How has the spray application affected
this problem?
Youngner: As far as the water repellent soils resulting from fire,
we have no information on that or what the relationship
of our particular study might be to those types of water
repellent soils because we've had no fire in recent
years through this experimental area. Our particular
soil on the site is not water repellent. We have no
difficulty in getting water into the soil, it's very
permeable. There is some variation but, in general the
permeability is high enough so that we have no problem
with the rates we're using.
Unknown: What's happening to the dissolved solids?
Youhgner: What's going to happen to the total dissolved solids in
that water? That's something I hope we will find out
in time. I don't know. This is one of the things we'll
be looking at and I think anything I could say on that
would be pure speculation at this point. We are probably
going to get a salt build up. Even though the salt
385
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content is not that bad, the two lower irrigation rates
in which we're not getting any deep penetration of the
water whatsoever, we are going to get a salt build up
in time.
Unknown: What affect will the salt build up have on the
vegetation?
Youngner: Many of the species we are using do accept a fair amount
of salt tolerance. Once the root system gets down to a
greater depth I don't think the salt problem is going to
bother the trees particularly. It will bother some of
the other vegetation, such as the grass and so on, which
are shallow rooted since the salt is going to be accumu-
lating on the surface and in the surface layers. The
shallow rooted plants are going to be most drastically
affected by the salt build up.
386
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MUNICIPAL WASTEWATER DISPOSAL ON THE LAND
AS AN ALTERNATE OF OCEAN OUTFALL
W. A. Cowlishaw and F. J. Roland
Bauer Engineering, Inc.
This paper attempts to take a look at land treatment as an
alternative to ocean disposal of partially treated industrial and
municipal wastes. The specific decision choice for Falmouth,
Massachusetts, a community located on the western end of Cape
Cod, will be used to highlight the political, engineering, and
resource management factor of decisions that juxtapose land
treatment against ocean disposal.
Present state plans (i.e. California) are moving toward
requiring a minimum of secondary treatment before ocean disposal and
toward the prohibition of ocean disposal of municipal and industrial
sludges. Selection of acceptable outfall locations is also becoming
a more complex process which will result in the need for more costly
transmission and outfall facilities. For example, the ability to
discharge into bays and harbor areas is becoming a thing of the
past.
An example of the problem of obtaining public acceptability of
an outfall location is the debate over the design of the new
Melbourne, Australia treatment plant. The Melbourne metropolitan
area (population 2.3 million) is located on the inner (west) side
of Port Phillip Bay at a distance of 35 miles from the Pacific
Ocean.
The original design for the 64 mgd treatment plant, located
on the north side of the bay, included an outfall into the bay.
Public pressure, however, has forced the development of a plan
to pipe the effluent from the plant a distance of 35 miles to
Bass Strait.
The problem of the treatment and final disposal of the ac-
cumulated sludge solids still must be dealt with. Indications are
that land application of organic sludges for agricultural utiliza-
tion will become a major management technique for this problem.
The City of Philadelphia, for example, is presently advertising
for bids to haul sewage sludge to land application sites in lieu
of ocean dumping.
387
-------
FACTORS RELATED TO OCEAN DISPOSAL
The principal interrelated factors of concern which form
the focus for the national debate on ocean disposal are sum-
marized in the following principal items:
1. Minimum level of waste treatment that will provide
a reasonable factor of safety for the ocean
environment.
2. Selection of an acceptable point of discharge for
any regional area.
3. Disposition of accumulated separated solids produced
in the treatment system.
4. Concern for potential long-term dynamic effects on
local and general ocean environment and ability
to develop cause and effect relationships.
5. Conservation and reuse of treated flows and con-
stituent materials.
6. Selection of plant locations acceptable to residents
of region.
7. Residual accumulation effects of periodic upsets
in treatment and reduced treatment performance during
periods of high stormwater flow.
LAND TREATMENT AS AN ALTERNATIVE
Land treatment provides a resources management choice to ocean
disposal for public and technical consideration. Performance aspects
of land treatment that offer attraction as a management choice
include:
1. Achievement of the highest level of treatment which
present technology can provide.
2. Return of renovated water to the immediately avail-
able water resource supply.
3. Recovery of nutrients and other materials to assist
in agricultural production.
4. Opportunities for multi-purpose site utilization
(solid waste disposal, industrial and power utility
cooling, recreational and open space uses).
388
-------
5. Ability to control, monitor and take corrective action
in impact areas of possible long-term deleterious
effects (heavy metals buildup in soils and crops,
nitrate buildup in groundwater).
As the level of required treatment increases no matter what
the discharge point or dilution potential, as the point of accept-
able discharge becomes more restricted and remote from metropolitan
centers and when the sludge disposal problem is required to be
dealt with in an environmentally acceptable manner, management at
land treatment sites will become increasingly attractive.
EVALUATION OF ALTERNATIVES FOR FALMOUTH, MASSACHUSETTS
The evaluation of land treatment versus ocean disposal for
Falmouth, Massachusetts constitutes a pilot study for the entire
Cape Cod area. Great concern exists on the Cape for the protection
of the local water supplies (in terms of both quality and quantity)
and the preservation of the recreational water environment. Pro-
jected population increases jeopardize both, threatening, in addition,
offshore shellfish beds, interior pond levels and natural assimila-
tive capacities.
As a manifestation of the concern, the Town of Falmouth has
been the center of heated public debate for the past few years
concerning selection of an acceptable management and facilities
plan for waste treatment. A proposed ocean outfall plan to dis-
charge wastes after receiving secondary treatment was rejected by
the townspeople by a 2 to 1 vote. Evaluation of other alternatives
was requested, specifically the cost and environmental consequences
of a land treatment system. The opportunity to develop a land treat-
ment plan was enhanced by the availability of a potential treatment
site at the Otis Air Force Base, which is scheduled for deactivation.
System Service Area
The design capacity of the system will serve the 1990 require-
ments of the Falmouth region, which has a sewered area population of
25,000 during the three summer months and a population of 16,000
during the remainder of the year. The generated flow is 2.7 mgd
during the three summer months and 1.6 mgd during the remaining
nine months. This results in an average annual flow of 1.9 mgd.
The areas served by the system would include Falmouth Center
and Woods Hole.
389
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Ocean Outfall Design
The ocean disposal system which has been designed for the Falmouth
area was prepared in response to water quality standards established
by the Massachusetts Water Resources Commission and the Federal Water
Pollution Control Administration. It has been reviewed and analyzed
by numerous engineering firms, and research and conservation groups,
including members of the Woods Hole Oceanographic Institution.
The system consists of three basic components: (1) a collection
and transport network, (2) biological treatment and (3) an outfall
system.
Collection and Transport System - This consists of the network
of sewers, force mains and pumping stations required to collect the
wastewater from the service areas and transport it to the sewage
treatment plant located at Woods Hole, 3,500 feet from Nobska Point.
Biological Treatment - The proposed activated sludge treatment
plant would be located on an eight-acre site in Woods Hole. Here,
the raw sewage would^pass through a pre-treatment structure, primary
clarifiers, aeration'tanks, secondary clarifiers and a chlorination
contact tank before final effluent disposal.
Outfall System - The outfall system for Falmouth consists of
a 30-inch diameter pipe extending 3,500 feet from the sewage treat-
ment plant to Nobska Point and an additional 1,950 feet out into
Vineyard Sound to a depth of 90 feet. At this location there
would be a minimum return of the effluent to beaches and harbors;
the tidal flow reaches maximum speeds; and the depth of the water
provides for maximum immediate dilution.
The ocean disposal system designed for Falmouth is expected
to meet all current secondary effluent standards of the Federal
government and the Commonwealth of Massachusetts.
The proposed outfall point has been the subject of considerable
study by experts from the Woods Hole Oceanographic Institution, and
the United States Geological Survey. It is regarded as the best
location for an outfall on the Cape if one is to be constructed.
However, at many other locations on the Cape it would be extremely
difficult, if not impossible, to obtain an outfall that would
approach the performance capability of the Nobska Point location.
This is because most of the Cape is surrounded by fairly shallow
ocean waters whose tidal currents are slow and which travel close
to bathing and shellfish areas.
390
-------
Land Management System
The land treatment system developed for the Falmouth area
entails the conveyance of wastes inland to a pre-treatment and land
irrigation site located within and adjacent to Otis Air Force Base.
The design capacity of the system will serve the 1990 requirements
of the Falmouth region and in addition a flow of 1.0 mgd generated
by Otis Air Force Base during the summer months and 0.4 mgd during
the remainder of the year. This results in an average total flow
during the year of 2.4 mgd. The system consists fo four basic
components: (1) a collection and transport network, (2) biological
treatment, (3) storage lagoons, (4) irrigation system.
Collection and Transport - The collection network consists of
72 miles of 4 to 24 inch laterals. The main transmission lines
consist of approximately 3 miles of 8 to 16 inch pipe from the Woods
Hole pumping station to the main Falmouth Center pumping station and
approximately eight miles of 18-inch pipe from the latter pumping
station to the Otis Air Force Base (AFB) sewage treatment plant.
Biological Treatment - The proposed wastewater irrigation
system incorporates the existing treatment facilities at Otis Air
Force Base. The base plant has been well maintained and can continue
to function as a secondary treatment facility for both Falmouth
and the Otis Air Force Base wastes.
The basic unit processes using the existing plant include:
(1) a sewage comminutor for solids reduction, (2) a diffused air
grease-skimming flocculation tank, (3) Imhoff tanks, which provide
for primary sedimentation of solids and for solids digestion;
(4) trickling filters, which provide biochemical oxidation of organic
matter in the sewage; (5) final settling, and (6) sludge drying
beds from which solids are returned to the land as a soil conditioner.
Storage Lagoons - Effluent from the final settling tank is
discharged to the storage lagoon, where further sedimentation occurs
and where the liquids are stored for irrigation. This component
of the system provides the necessary flexibility for storing
wastewater during periods of heavy rainfall or freezing temperatures.
The storage lagoon is sized to permit detention of four months
of winter flow (267 mg). Its surface area is 54 acres, with a
working water depth range of 13 to 33 feet. This variable depth
results from a lagoon design which takes advantage of the natural
topography, thereby minimizing excavation costs.
Irrigation System - The irrigation site area is located in
Mashpee Outwash Plain consisting of glacial deposits of sand and
gravel. These deposits are very permeable and previous well tests
in the area indicate that the proposed wastewater site is geologi-
391
-------
cally well suited for spray irrigation. Approximately 250 feet
beneath the surface of the site lies the hard, dense basement
rock.
The total required site including treatment facilities, storage
lagoon, irrigation and unused buffer areas is approximately 800
acres. The actual required irrigation area is 490 acres based on a
2-inch per week application rate for an 8-month annual application
period.
The method of water application would depend on the final
areas selected for use. At present tracts of cleared flat land
within the Otis Air Force Base site and a forested game conserva-
tion area are being considered for use.
In cultivated areas rotating irrigation rigs would distribute
the wastewater on the land. In forested areas a fixed system would
be used to minimize the disturbance of the natural setting.
Groundwater Flow
The water applied to the irrigation area will be allowed to per-
colate through the soil into the groundwater supply. The performance
of the wastewater management system will be continuously monitored
to assure protection of the groundwater supply near the irrigation
site.
Due to the possibility of salt water intrusion, the recharge
of groundwater is considered of primary import. Several preliminary
studies have been undertaken to estimate the change in groundwater
flow due to the application of water- at the irrigation site. In
general, it is calculated that approximately 775 million gallons
of water will be returned to the ground at the spray irrigation
site. This is equal to 84 per cent of the total of 920 million
gallons of wastewater .treated.
Analyses indicate that the groundwater flow changes would be
greatest in the vicinity of Coonamesset Pond, toward which some 70
per cent of irrigation water will flow. The Ashumet Pond will receive
20 per cent and the area between these two ponds would receive 10
per cent. The estimated dilution of irrigation water to groundwater
is in the order of magnitude of one to one.
ALTERNATIVES COMPARISON
Evaluation of ocean outfall versus land treatment for Falmouth
must consider both cost and performance (impact) differences between
392
-------
the two systems.
Cost Comparison
Estimated facilities development and operating costs for the
two alternatives are listed in Table I. The land treatment system
is shown to be least expensive on a unit capacity basis. This is
due to the incorporation of the existing Otis Air Force Base
facilities in the land system.
Table 1. Comparison of Total Construction Costs for Phase I
of Alternative Systems
Land
Treatment
Ocean
Disposal
Cost of Facilities I/
Design capacity in mgd
2.4 1.9
Wastewater treatment
facilities
Pumping station and force
mains
Gravity sewers
Subtotal
Land acquisition
Engineering, legal and
administration
Total
Capital cost per mgd
capacity
Annual operating cost
Average annual total cost
per mgd capacity
$2,130,000
2,440,000
. 3,890,000
$8,460,000
600,000
846,000
$9,906,000
4,127,000
83,000
$ 336,000
$3,390,000
1,460,000
3,890,000
$8,740,000
75,000
874,000
$9,689,000
5,099,000
85,000
$ 417,000
I/ Utilization of existing Otis Air Force Base facilities is
not entered as a cost item in land treatment system. Cost of
land for land site is estimated equivalent value not actual
price paid in any project. Annual costs based on 30 year
bonding at 6% interest.
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Impacts Assessment^
The impacts of the alternative systems on the Cape Cod
environment can be assessed in terms of the effects on the fresh
groundwater table under the Cape and in terms of the effects on
shoreline water quality.
Ocean Disposal
This analysis is based on an ocean outfall which it is generally
agreed, would offer acceptable levels of discharge and mixing and
which would minimize the chances of any effluent returning to har-
bors, beaches or estuaries of the Cape.
1. Probably the most serious implication of the ocean outfall
system is that it diverts a substantial portion of the
potential groundwater recharge, finally and irretrievably.
After treatment, the entire amount is diverted to the
costal waters. Consequently, if pond lowering or in-
trusion occurs, remedies would be quite costly. It has
been estimated that the amount which can be diverted without
damage cannot exceed ten to twenty-five per cent of the total
annual groundwater recharge of the area serviced. The
estimated peak summer population of 1980 (497,000) would
withdraw, although not necessarily divert, at a rate
equal to approximately twenty-five per cent of the annual
recharge.
2. A maj or impact of the treated sewage effluent on the ocean
is that of nutrients: carbon, phosphorus and nitrogen.
Although a certain amount of these elements is required
to maintain seafood productivity in costal waters, ex-
cessive levels cause an overabundance of organic production
with consequent undesirable effects on water quality.
3. In addition to the overall performance of the ocean outfall
system (treatment and dilution levels), attention should
be given to the reliability of the treatment plant itself.
Shock loads, which occur quite frequently, could result
in the dumping of untreated wastes for substantial periods
of time, directly into the ocean.
4. Another consideration is the possible pathogenic bacterial
or viral contamination of the receiving water. The effects
of such contamination would largely relate to the shellfish
areas which are an important economic sector for the Cape.
5. Excessive amounts of organic carbons and toxic substances,
such as heavy metals and non-biodegradable hydrocarbons
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could cause long-term deleterious effects and should be
excluded from any marine outfall system. These elements
are rarely found in the Cape wastewater because of the
relative lack of industry.
A final point is that sludge resultant from the treatment
process must be handled outside the system. Separate
dumping or spreading areas must be acquired or secured
for these waters and procedures established to reduce odors
and control leachate.
Land Treatment System
1. The spray irrigation system will return renovated water to
the groundwater resource of quality suitable for reuse.
If the water is returned at a point proximate to that of
withdrawal, it can be considered to be replenishing the
developed water supply source. If not, it simply adds
to the availability of fresh water on the Cape. There
is, therefore, the flexibility of withdrawing and trans-
porting the treated water for use in injection wells or
retention ponds to impede instances of intrusion or
pond lowering.
2. The irrigation waters supply nutrients and organic matter
to the land in sufficient quantities to enhance plant growth.
This permits the conservation of commercial fertilizer
which poses a special pollution problem in itself.
3. In contrast to the ocean disposal system, the spray
irrigation system provides for disposal of both sludge
and the septic tank pumpings. After adequate treatment,
the activated sludge, including the treated septic tank
solids, can initially be applied to the irrigated land as
a soil conditioner; it can later be applied to those
areas which are not routinely irrigated.
4. The spray irrigation system requires an extensive amount
of land. Average requirements vary according to the design
application rate, or length of irrigation period. For
Cape Cod the land requirements are typically in the range
of 200 acre per mgd, based on average annual application
rates. Opportunities to alleviate some of the problems
of site acquisition are discussed elsewhere in this paper.
5. Irrigation areas can be an asset to the community, however,
by providing useful open space. Other potential benefits
include the control of urban sprawl and the perservation
of agricultural use areas.
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CRITICAL FACTORS IN LAND TREATMENT SYSTEMS
The two major aspects of land treatment systems that are the
focus of debate on general acceptance are: (1) the social and
institutional problems of site acquisition and (2) the possible
long-term effects of toxic substances on soils and crops.
Site Acquisition
Acquisition of large land site areas and the relocation of
activities located thereon can create severe institutional, politi-
cal, legal, and cost difficulties. In the Muskegon County project
the decision was made to acquire and clear the irrigation site of
private activities. This was dictated by regulatory requirements
and characteristics of site ownership.
The Falmouth situation, on the other hand, documents the
improved implementation potential achievable through joint Federal,
State, and local cooperation. Such opportunities would likely be
available for many locations along the U.S. coastline and at
interior locations. For example, the programmed closure of many
military bases presents a special site development opportunity
at many locations in addition to that of Falmouth.
In other situations the acquisition problem could be relaxed
through the development of irrigation lease arrangements with local
farmers. This has been practiced in California and other areas.
Toxic Effects
The problem of potential long-term accumulation of toxic sub-
stances in the soil and crops is an issue that is currently being
given extensive attention. There have been cited experiences of
metals buildup in soils, increased crop intake and reduced crop
yield. There has also been experiences (notably, Melbourne) of
long-term operations with no apparent reduction in performance.
In any assessment effort, it is important that information on metals
buildup in soils and crop uptake with land treatment systems under
study be related to naturally occurring variations to establish
significance of change in any comparative analyses. Process dynamics
in nature are subject to many-fold variations.
The uncertainty factor for a long-term toxic effects on land
appears to be more critical than that which ocean outfall poses for
the marine environment. The relevant questions are, "What is a
potential toxic effect of sewage and what are the relative hazards
of the impact areas for the various management choices - air, land
and water?"
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As indicated previously in this paper, the ability to control
the effects of a land system to a specific site and the capability
to continuously monitor this controlled environment, gives land
treatment a strong environmental safety margin.
Land application permits the development of a discrete control
break in the food chain back to man and presents many opportunities
for corrective action with the identification of a developing
problem. Corrective action includes: crop rotation, deep plowing,
and limeing. Such control is not feasible in the diffuse aquatic
environment of the ocean with its complex overlapping food chain
linkages.
CONCLUSIONS
The foregoing analysis indicates that the land disposal-
spray irrigation alternatives for managing wastewater would better
serve the needs of the Falmouth region - and those of the entire
Cape - for its effects in treating wastewater; the spray irrigation
system is superior; its pollutant removal efficiency clearly exceeds
the ocean outfall system in its effective removal of pollutants.
In addition to the efficiency and reliability of this system
for purifying wastewater, it provides numerous related benefits
applicable to the regional water resources. These include:
1. The spray irrigation system returns a large percentage
of the treated wastewater to the groundwater resources.
There is no diversion of water. In addition, the
returned water is of a quality suitable for public water
supply.
2. The system offers flexibility for retrieving the
treated water and transferring it to critical areas
of local water table or pond level drop or salt water
intrusion.
3. The irrigation of marginal land for agricultural
purposes will provide some usable crop - possibly
grasses for fodder. The irrigation of forested
land will increase production of the undergrowth
for game food sources and permit additional monitoring
of the site.
4. The utilization of wastewater for land irrigation will
virtually assure that there will be no adverse affect
on any marine life or on the recreational value of the
Cape waters.
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5. An integration of the spray irrigation site with
numerous other publicly funded projects can achieve
such multiple purposes as curtailing urban sprawl
or providing additional recreational open space
areas.
All of the above advantages of the spray irrigation system
are achievable at costs comparable to those for conventional secondary
wastewater treatment.
PRESENT STATUS OF PROJECT
At the March 6, 1972 Falmouth Town Meeting, the preparation
of a definitive land treatment system engineering report was a
authorized. This work is to be done by Bauer Engineering, Inc.
with assistance by Anderson-Nichols § Company, Inc. of Boston.
Pending final approval of the contract by the Falmouth
Department of Public Works and the scope of the work by the Mas-
sachusetts Water Resources Commission, Department of Public
Health and the Division of Fisheries and Game, the report containing
preliminary designs and layouts for the land treatment system
will be prepared. This study, which will provide the information
needed for State and Federal approval, detailed design and pre-
paration of construction contract documents, will also review
alternative treatment arrangements, irrigation site areas and
conveyance facilities from the Town to the Otis AFB site area.
Since the Town Meeting, approval for use of the originally
designated Otis AFB lands has been obtained. Another subsequent
event has been the announcement that the U.S. Air Force activities
at the Otis AFB are being terminated with control of the facilities
reverting to the state. Consequently, there will be investigations
to determine if additional areas can be utilized for irrigation
at this site.
Upon completion of this work, it is anticipated that a Town
Article will be presented to a future Town Meeting for authorization
for the preparation of contract documents needed for construction
of the project.
DISCUSSION
Unknown: Give us the status on this 1970 act that was passed by
Congress concerning ocean dumping and how it will affect
the ocean outfall.
Rohland: I'm not familiar with the exact timetable on the federal
act. There are also a number of state legislative
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activities which deal with sludge management and with the
quality of water that you have to achieve before you dis-
charge to the ocean.
Adams: What about the infiltration rates on the land? I would
assume that it is pretty sandy soil.
Rohland: I didn't go into a description of the site itself other
than to say it's a sandy outwash plain, but it consists
of highly permeable sand and gravel material to a depth
of about 50 feet where the water table is located.
Unknown: Would you propose any conditioning to slow down the
permeability?
Rohland: What we are proposing now is a rate of application in the
order of about 2 inches similar to what's being done in
many areas. We are not proposing any conditioning of the
surface itself. It's the top two or three feet that can
provide adequate renovation. We will have a monitoring
system installed to evaluate the water that percolates
through to the groundwater reservoir.
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THE ROLE OF LAND TREATMENT OF WASTEWATER IN THE CORPS
OF ENGINEERS WASTEWATER MANAGEMENT PROGRAM
James F. Johnson
Wastewater Management Task Force
U.S. Army Corps of Engineers
The continuing problems of environmental degradation, par-
ticularly that caused by the discharge of a broad spectrum of
pollutants into our water courses, have prompted the Corps of
Engineers to assist State, regional, and local governments in
developing wastewater management plans toward their solution. As
a part of its urban studies program, the Corps will develop an array
of plans in consonance with local planning agencies from which the
people of the region could choose the specific plan which best
meets their needs.
Wastewater management systems are comprised of structural and
non-structural components to collect treat, transport, reuse, and
dispose of all sources of waterborne wastes. These systems must
be comprehensive in scope; they cannot ignore sources of pollutants,
technologies, institutions, impacts, or public preferences. This
paper will address the role of land treatment in the Corps of
Engineers Wastewater Management program, with particular emphasis
upon its relationship to the planning process, the impacts associated
with land disposal, and certain research needs related to land
disposal of wastewater (Johnson, 1972).
The Department of the Army initiated a pilot Wastewater
Management Program late in FY 1971 concentrating initially on
municipal, industrial, and urban storm runoff wastes. It is expected
to complete this pilot program in four major urban areas in FY 1973.
These areas are Cleveland - Akron, Detroit - Southeastern Michigan,
Chicago - Northwest Indiana, and San Francisco - Sacramento-
Stockton. These studies are being conducted in cooperation with all
appropriate State and local governmental units as well as the
Environmental Protection Agency. In July 1971, the Corps prepared
interim feasibility reports for the four areas in addition to the
Merrimack Basin in New England (U.S. Army Corps of Engineers, 1971a,
b,c,d,e). On a more local scale, the Corps also is developing
wastewater management plans for the people of Codorus Creek in
Pennsylvania. Currently, a number of urban studies are being initi-
ated that will meet a broader range of urban water needs, and waste-
water management could provide benefits in the areas of flood
'protection, water supply, and recreation, to mention only a few.
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PROGRAM OBJECTIVE
The wastewater program is directed toward improving the
economic, social, and environmental welfare of the Nation and, in
particular, the regions under study. The effects of the wastewater
management plans will be measured in accordance with the broad
objectives proposed by the Water Resources Council (U.S. Congress,
1971).
In order to effectively plan and measure the performance of
wastewater systems in contributing to the objectives, we must first
identify specific planning objectives (or needs) which the system
will address. The subsequent evaluation of wastewater management
systems in terms of these planning objectives would provide the
basis for comparison of alternatives. These planning objectives
would address such issues as economic growth policies, resource
use policies, and desired land use patterns. The planning objectives
of the region will be specified in such detail as to preclude
consideration of alternatives in direct conflict with higher priority
objectives. For instance, elimination of an ecological resource
or isolation of a community or segment thereof by an alternative
system would constitute a condition that is not acceptable.
PLAN FORMULATION
The process of plan formulation is one involving a series of
iterations whereby plans are developed, evaluated, screened, and
redeveloped or refined. Specific technical goals direct the waste-
water systems toward achieving these objectives.
These technical goals are: (1) to prevent the continued
degradation of our water resources by waterborne wastes; and
(2) to provide for the efficient reuse of treated or renovated
wastewater and by-products. Achievement requires the application
of the best technology for the. collection, treatment, and management
of wastewater (U.S. Army Corps of Engineers, 1972a). At successive
screening stages, alternatives will be evaluated in conjunction with
an active program of public involvement to assist the development
of-optimal plans. The refinement of the alternatives that remain
through this screening process will reflect the desires expressed
in public involvement.
Existing institutions that are related to the management of
water and wastewaters will be identified but these will not con-
strain the development of optimal wastewater management systems.
The impacts of the plan on existing institutions will be analyzed,
and a series of alternative implementation plans will be developed.
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The selection of optimal wastewater plans will be made on
the basis of the evaluation of beneficial and detrimental effects
of the alternative, as well as a consideration of its associated
opportunities and concerns. Information will be presented and
displayed to illustrate the comparative differences among al-
ternatives, their cost-effectiveness, and benefits and opportu-
nities foregone by selecting one alternative vis a vis the others.
In so doing, the presentation will clearly identify the detrimental
effects of each alternative, and to what degree these could have
been or could be eliminated. This information will be displayed
in such a manner that responsible decision-makers may observe the
difference between systems as they relate to major issues and
concerns in the study region.
WASTEWATER TREATMENT SYSTEMS
In order to meet the program technical goals, the wastewater
systems will employ the most efficient biological, chemical, and
physical waste treatment processes (including the soil-vegetative
complex) or combinations of these. These processes will be em-
ployed in the land treatment systems as well as the more tradi-
tional treatment plant systems.
The land treatment facilities being designed generally would
consist of biological treatment cells, storage basins, application
facilities, and land treatment areas; as well as underdrains or
other collective systems to provide for the reuse of treated
wastewater. Three means are under study for the application of
wastewater on the land:
Spray irrigation is defined as the controlled spraying of
liquid onto the land, at a rate measured in inches per
week, with the path being infiltration and percolation
within the boundaries of the land disposal site.
Overland runoff is defined as the controlled discharge,
by spraying or other means, of liquid onto the land, at
a rate measured in inches per week, with the flow path
being downslope sheet flow.
Rapid infiltration is defined as the controlled dis-
charge, by spreading or other means, of liquid onto the
land, at a rate measured in feet per week, with the flow
path being high rate infiltration and percolation (U.S.
Army Corps of Engineers, 1972b).
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Application of Wastewater to Land
The wastewater systems will be planned to promote the wise use
of wastewater resources in addition to meeting the water quality
non-degradation goal. Significant benefits can be provided with
proper planning and operation of the systems.
Because wastewater is a source of nutrient-rich irrigation
water, it can be applied to improve the productivity of marginal
agricultural lands or improve upon presently productive farmland.
In particular, crops with high nitrogen requirements can be en-
hanced by the properly controlled application of wastewater. In
addition, the nutrient-rich water can be applied to forest lands,
recreation areas, and other open areas. Such use of wastewater
throughout the United States is well documented (Law, 1968;
Whetstone, 1967).
Wastewater also could be applied to degraded land such as strip
mines and fallow lands to enhance them for future use. Certain lands
also can be preserved for planned future use by creating "land
banks" through interim use as land treatment sites.
Wastewater Reuse
The renovated wastewater cleansed by the soil-vegetative filter
system will be available for reuse for a wide range of purposes. The
water could be percolated to recharge the groundwater aquifer. In
general, however, the systems call for collecting the cleansed
effluent and returning it for specific uses. Reuse opportunities
will be identified on the basis of the needs of the region for
possible stream flow augmentation, recreational lakes, industrial
cooling, industrial process water, industrial boiler feed, and
municipal reuse.
Multiple Use of Land and Facilities
There also is an opportunity for the multiple-use of the land
and facilities required for wastewater systems. With regard to
land treatment systems, we are studying such opportunities as the
use of storage lagoons to accept and beneficially use thermal
discharges from power plants; the use of irrigation and treatment
sites to provide habitat area that could be used for hunting and
other recreation; and use of transmission rights-of-way for trails,
bikeways, controlled access roads, and utility routes.
There also are significant opportunities in planning for the
efficient multiple-use of the required larger tracts of land.
In many instances, land treatment sites may favor sites somewhat
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distant from population and congestion. The opportunities to locate
facilities such as airports, that seek these same characteristics
should be identified within the framework of these regional plans.
The desirability and potential for siting new towns and regional
industrial parks also will be investigated.
FEASIBILITY STUDIES
The feasibility studies were intended to identify the present
and future wastewater management problems and to make a preliminary
evaluation of the feasibility and consequences of alternative
wastewater management plans in the five regions. In transmitting
these feasibility reports to the Secretary of the Army and the
Congress, the Chief of Engineers concluded that,
There are major improvements possible in the effective-
ness of wastewater management systems to remove a broad
spectrum of waste constituents be those systems water
disposal, land disposal, or some combination thereof;
There exist important opportunities and benefits as-
sociated with truly comprehensive wastewater management
systems for water and waste constituent reuse, including
the potential for new water supplies and recreation; and
for a broad range of previously untapped opportunities
related to social and environmental enhancement (U.S.
Army, Secretary of the Army, 1971).
Of particular interest are the Chief of Engineers additional
conclusions that,
Wastewater management systems requiring disposal to the
land offer potentially new opportunities in selected
areas including increased land production, management
and reuse of wastes generated from other activities,
and improvements, to environmental quality and regional
coranunity values;
Further investigations and studies are required with
respect to technological concern for both water and
land disposal alternatives. Such investigations must
evaluate:
(a) The effectiveness, reliability, and flexibility
of large-scale advanced wastewater treatment
facilities, both physical-chemical and biological
processes;
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(b) The long-term viability and integrity of the land
to serve as a natural processor of wastewater, and
(c) The relative toxic effects of viruses, patho-
genic bacteria, trace metals and other toxic mate-
rials upon the environment whether land or in
receiving waters;
The institutional implications of the alternative waste-
water management strategies will be most critical to any
future decisions regarding implementation, and that
future studies must fully address such consequences
and suggest appropriate means to facilitate necessary
institutional changes (U.S. Army Secretary of the Army,
1971).
Survey - Scope Studies
The Congress acting upon the recommendations of the Secretary
of Army and the Chief of Engineers gave approval in late 1971 for
the Army Corps of Engineers to proceed into the survey-scope
stage in Cleveland, Chicago, Detroit, and San Francisco studies
in FY 1972. The Merrimack study in Massachusetts is being resumed
in FY 1973.
STATE-OF-THE-ART
Concurrently, the Corps has undertaken state-of-the-art
investigations to summarize the available knowledge relating to
the feasibility of land application as a wastewater treatment
process. The Army Corps of Engineers Cold Regions Research and
Engineering Laboratory (CRREL) and a group of research consultants
at the University of Washington agreed to prepare independent
comprehensive technical assessments of the effectiveness and effects
of land disposal of secondary treated wastewater (Reed, 1972;
Driver,et al, 1972).
Each group studied spray irrigation, overland runoff, and
rapid infiltration methods of application and treatment. Prepara-
tion of the reports included literature reviews, correspondence
with experts involved in existing operations and current research,
and personal observations at selected sites. The following were
among the most significant conclusions:
(a) The quality of cleansed effluent produce derived from a
properly designed and operated land disposal facility would approach
drinking water-irrigation water standards.
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(b) The land disposal facility and the pretreatment steps
must be carefully managed as a total system to provide optimum
responses.
(c) Any one of the three application modes can meet the quality
standards if proper site conditions exist and proper operational
criteria are employed.
(d) Spray irrigation offers the highest degree of relability
and potential longevity of the three modes.
(e) Heavy metals are largely removed from wastewater applied
via spray irrigation, with the main mechanisms being ion exchange
and fixation.
Both groups concluded that further investigation was needed,
particularly in (a) overland runoff removal effectiveness; (b)
transport of N and P to surface waters through erosion of over-
land runoff sites; (c) wind transport of pathogens by aerosols;
(d) soil-chemical interactions, to include heavy metals; and (e)
interaction of soils, climates, and loading rates to manipulate the
carbon-nitrogen ratio.
Current Investigations
Accordingly, the Corps of Engineers is presently involved in
exploratory efforts to (a) investigate the effectiveness of rapid
infiltration basins at Fort Devons, Massachusetts, and Army in-
stallation; (b) analyze soil samples from Melbourne, Australia's
sewage farm at Werribee; (c) develop and investigate performance of
spray irrigation test cells (28 feet square, 5 feet deep) at
CREEL; and (d) evaluate groundwater conditions in a joint effort
with the U.S. Geological Survey and the city of Tallahassee,
Florida, at the Tallahassee spray irrigation site.
Chicago Special Report
In proceeding through the survey-scope stage of the waste-
water management pilot studies, the continued refinement of design
costs have resulted in a position for land treatment systems more
favorable than their position as presented in the feasibility
reports.
In order to place the cost of alternative systems in per-
spective, the Chief of Engineers early in 1972 undertook a special
study of the Chicago Metropolitan area with the assistance of Bauer
Engineering for the purpose of (a) formulating the least-cost
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wastewater management system alternatives; (b) detailing capital
costs and operation, maintenance, and replacement costs of the
alternative systems; and (c) analyzing the relative merits of
alternative systems.
Although it is recognized that the special study was limited
to providing a view of basic land, physical-chemical, and advanced
biological treatment systems, the results underscore the com-
parative economic technical feasibility of land treatment
systems.
Specifically, the study concluded that (a) significant strides
can be made toward achieving comparably high levels of treatment
by all three alternatives studied. These levels appear to be compati-
ble with the current Corps program technical goal of minimizing
water quality degradation from waterborne wastes; (b) costs of
any one of the systems involves several billions of dollars; and
(c) costs for land treatment may be lower both for capital and for
operation and maintenance (U.S. Army Corps of Engineers, 1972b).
The current wastewater studies are now well underway through
the survey-scope stage. The Corps of Engineers Districts are
conducting these studies through a balanced use of in-house manage-
ment and technical capabilities supported by the technical expertise
of architectural and engineering consultants and scientific research
firms.
CONCLUSION
The Corps of Engineers recognizes its responsibility to the
Nation and the regions under study to provide an array of com-
prehensive plans addressed to their overall needs. We seek to meet
these needs through a planning process in which the full range of
technologies is explored, the impacts associated with these
technologies are addressed, and the resulting plans achieved within
the framework of public involvement are set forth to the people of
the regions to assist in their choice. The Corps is not committed
to specific technologies,but is convinced that all technologies,
including both land application and treatment plant systems, must
be investigated thoroughly in order to broaden the range of choice
available to allow decision-makers to act in the best public in-
terest.
REFERENCES
Driver, C. H., B. F. Hrutfiord, D. E. Spyridakis, E. B. Welch,
D. D. Wooldridge and R. F. Christman. 1972. Assessment of the
effectiveness and effects of wastewater management. U.S.
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Army Corps of Engineers Wastewater Management Report 72-1.
Johnson, James F. 1972. Regional wastewater management: a new
perspective in environmental planning. Water Resources
Bulletin 8 (4), 773-779.
Law, James P. 1968. Agricultural utilization of sewage effluent
and sludge, an annotated bibliography.U.S. Federal Water
Pollution Control Administration, Wash. D. C.
Reed, S. C. 1972. Wastewater management by disposal on the land.
Special Report 171, Cold Regions Research and Engineers, Han-
over, N. H. p. 10-18.
U.S. Army Corps of Engineers, Buffalo District. 1971a. Alterna-
tives for managing wastewater for Cleveland-Akron Metropolitan
and Three Rivers Watershed Areas.Summary and three appendices.
U.S. Army Corps of Engineers, Chicago District. 1971b. Alterna-
tives for managing wastewater in Chicago-South End Lake
Michigan Area. Summary and appendices?
U.S. Army Corps of Engineers, Detroit District. 1971c. Alterna-
tives for managing wastewater for Southeastern Michigan.
Summary and ten appendices.
U.S. Army Corps of Engineers, San Francisco District. 1971d.
Alternatives for managing wastewater in the San Francisco
Bay and Sacramento-San Joaquin Delta Area. Summary and six
appendices.
U.S. Army Corps of Engineers, North Atlantic Division. I971e. Hie
Merrimack: designs for a clean river. Summary and appendices.
U.S. Army Corps of Engineers. 1972a. Office, Chief of Engineers.
Wastewater Management Program: study procedure.
U.S. Army Corps of Engineers, Office,Chief of Engineers. 1972b.
Regional wastewater management systems for the Chicago Metro-
politan area.Summary and appendix.
U.S. Army, Secretary of the Army. 1971. Interim report of the
Secretary of the Army of the Pilot Wastewater Management
Program.
U.S. Congress. 1971. Procedures for evaluation of Water and
Related Land Resources Projects Committee print 92-20. Wash.
D.C.
Whetstone, G. A. 1967. Re-use of effluent in the future with an
annotated bibliograpEyiTexas Water Development Board, Austin,
Texas.187 p.
DISCUSSION
We've had considerable experience with land irrigation in
Pennsylvania as you know, and also lagoon systems and we've
found that many of them have failed because the work that
led up to them was fine in the engineering area and fine
in the economic area but very thin in the hydrogeological
area. I have this same kind of concern about some of the
papers and studies that are being made by the Corps of
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Engineers. For example, in Mr. Bauer's paper there's very
little discussion of the hydrogeologic renovation capa-
bility. What specifically are the standards that the Corps
is establishing for the hydrogeologic aspect of these
studies?
Johnson: The Corps systems would be able to meet the standards set
forth by the Environmental Protection Agency. In other
words, they would meet the minimum requirements of any
regulation that would be set forth by the EPA. Before we
went into any advanced engineering designs today I think
the Corps' engineering division, which I think is beyond
question as far as intense investigation requirements,
would require some sort of an investigation. I'm not sure
of the specific items since I'm not representing our
engineering division.
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MICHIGAN'S EXPERIENCE WITH UTILIZING THE TEN STATES
GUIDELINE FOR LAND DISPOSAL OF WASTEWATER
Donald M. Pierce
Division of Wastewater
Michigan Department of Public Health
Our experience with land disposal systems in Michigan is very-
limited. For although nearly 50 communities have designed systems
of this kind, only 2 of these have been in operation longer than
one year. The widely publicized Muskegon County project will not
be in operation until 1973. By the end of this year 15 muni-
cipal spray irrigation projects and 5 using spreading or flooding
basins will have been completed and in operation, and by the end
of 1974 this number will have increased to about 50. Nearly
all of these projects are in advanced planning stages. Thus we
have had a rather extensive opportunity to use the guidelines
adopted by the Great Lakes - Upper Mississippi River Board of State
Sanitary Engineers -' the so-called "Ten States Standards" (Ground
Disposal of Wastewaters, 1971). We have used them with increasing
respect and enthusiasm as our experience is extended to an ever
widening variety of field conditions. We do not, however, regard
them as standards or rigid requirements any more than we do with other
facilities, processes and practices for which standards or guidelines
have been developed by this group.
Even in this early stage of operational experience some
critical deficiencies in design have come to light. We are just
beginning to recover from the shock of a series of misjudgments and
oversights in technical areas new to us and not customarily within
the experience of sanitary engineers --at least those in the east
and midwest. With these admissions I should hasten to say that
the problems which have surfaced so early in the growth and
development of an offspring heralded as the best hope of the ardent
ecologist could probably have been avoided -- all of them -- had
the Ten States guidelines for ground disposal of wastewaters been
put into practice. The real problem in each case was some lack of
understanding, both by the engineers designing the system and those
evaluating and approving the design, of the natural forces which
control the destiny of complex constituents of the waste particle
when applied to the soil. It was not that he did not realize that
he was dealing with matters a bit outside of his field. He knew
this. It was not that he did not seek advice of other professionals
more knowledgeable and experienced than he in these matters. He
did this. He conferred with the hydrogeologist or geohydrologist,
the soil scientist, the crop specialist, the irrigation specialist
and the drainage engineer. He did talk with them and read some of
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their publications. He even provided them with some data and
got some advice on how much more information and what kind was
really needed to refine the design of the system. But here in his
blissful ignorance he got off on the wrong foot. He made some
value judgments of his own with too little information and just
possibly too little real understanding and then he wrapped up the
project for construction. Let me elaborate just a little on
where he went astray on one project.
A piece of land was chosen after a long search for spray
irrigation of wastes from a community of about 2,000 with no
adverse industrial waste constituents. Pretreatment was to be
provided by primary sedimentation and aerated lagoons followed by
disinfection. Wastes were to be spray irrigated on some 75 acres
during roughly April - October with provision for 5 months winter
storage of the treated wastes. The treated wastes were to be
sprayed at an average rate of 2 inches per week on a 16-hour
a day basis. All wastes were to be contained within the property.
Drainage systems traversing the property were to be abandoned or
rerouted around the property. Soil borings on the spray area were
interpreted to indicate a percolation capacity sufficient to
accommodate the average 2-inch application rate with rates during
dry warm weather periods at least double this. This was their
first big mistake. No underdrainage was proposed. This was the
second big mistake.
The first indication of trouble obvious to the community and
its engineers was much higher sewage flow than anticipated. This
came to light the first year when the storage lagoon with projected
•capacity for 5 months storage overflowed in early January. During
the ensuing eight months since then, soils have been demonstrated
to be incapable of accepting rates of this magnitude without
underdrainage and probably not even if good underdrainage. Runoff
from the property to nearby drains has continued throughout the sum-
mer months. Ponding in low areas has been severe and extensive.
What are the consequences of this lack of predesign investigations
and thorough analysis? 1) Gross nuisances from the ponding of
wastes both on the property and on neighboring properties 2)
Discharge of inadequately treated wastes to the surface waters of
the state exceeding stream standards, and 3) Continuance of these
conditions until a fully adequate program is devised and implemented.
Correction may require construction of an underdrainage
system, acquisition of more land and installation of more irrigation
equipment. It will also require considerations on vegetative
cover, cropping regimens and other management aspects.
In somewhat similar circumstances, two small communities have
developed land disposal systems, each utilizing spreading or flooding
basins following raw waste stabilization lagoons. Both communities
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are quite small, using about IS acres of land for irrigation to
serve a population of less than 1,000. In both locations the basins
were designed to accommodate an average application rate of about
3 inches per week for the 6 months period with storage in the
lagoons for the winter 6 months. In each community, lagoons were
placed in operation this spring with less than 75 percent of the
properties connected to the sewer system. At our suggestion, one
community directed its engineers and a geologist to confer with
soil scientists and others to more fully evaluate the soil's
capability. Preliminary analysis indicates application rates
should be reduced to about one inch per week. Studies are con-
tinuing. At the other community soils are believed to have even
less percolation capability. Obviously modifications, both
in construction and management methods, must be made by each com-
munity to avoid serious pollution problems and gross nuisances.
These cases illustrate unsatisfactory performance attributable
to tight soils with loading capabilities less than assumed in the
design of the system, coupled with high ground waters, inadequate
drainage and in one case topography conducive to sheet runoff. A
quite different set of problems arise, of course, where soils
have an extremely high percolation capability with groundwater
moving from the disposal site to wells used for domestic water
supply. In some respects, however, the designer and his special
corps of technical consultants can identify and quantify the pro-
blems and their solutions for these conditions with greater precision
and confidence than in other less obvious circumstances. Some soils
obviously are more difficult to analyze than others as to their
hydraulic capability and their ability to remove certain pollutants
under a variety of weather conditions, application rates, cropping
regimens, drainage systems and other effects. Perhaps most difficult
of all are intermediate and long-range behavior patterns.
I must confess that as a state regulatory group we have had
less than a delightful experience with land disposal design and
operation. Our lack of experience has led to periods of uncertainty
and apprehension. We have had to become familiar with technologies
strange to us and have become more dependent on the judgment of
technicians in a host of special, related disciplines. In some
quarters we have been charged with unwarranted conservatism for our
judgments in some aspects of design and operation. Quite para-
doxically, these same judgments are sometimes viewed by those who
oppose the land disposal concept as ridiculously generous in
approving systems surely doomed to failure. There is room for both
agitation and humor when you stand your ground in the middle.
Surely the most productive and rewarding experience we have had
in administering this phase of our water pollution control program
is working with the professionals who have had a great depth of
knowledge in the many special fields involved. We find them in
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state departments of Agriculture, Health and Natural Resources
and in similar fields of work at universities and research in-
stitutions. It has been heartening to see how they can apply
their knowledge to these problems in a truly team fashion and to
witness their enthusiasm to delve into the more obscure aspects
related to the peculiar and wide ranging characteristics of
wastewaters in an equally diverse environment. This conference
here this week exemplifies this interest and involvement.
We in Michigan have given the guidelines adopted by the
Standards Committee of the Great Lakes - Upper Mississippi River
Board of State Sanitary Engineers a good test this past year. With
each project review and each field experience we are increasingly
impressed that they are soundly conceived and fairly stated. They
are gaining favor and acceptance with designing engineers and
their consultants as a. working guideline and basic reference.
We commend them, as such, for your thoughtful and critical
consideration and use.
REFERENCES
Ground Disposal of Wastewaters. 1971. Addendum no. 2 to recom-
mended standards for sewage works. Great Lakes - Upper Missis-
sippi River Board of Sanitary Engineers.
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FOREST SERVICE POLICY RELATED TO THE USE OF NATIONAL FOREST
LANDS FOR DISPOSAL OF WASTEWATER AND SLUDGE
01af C. Olson and Edward A. Johnson
Division of Watershed Management
Forest Service, USDA
At this time the most accurate statement concerning the
Forest Service's position to disposing of wastewaters and
sludges on National Forest land is that it is one of cautious
optimism. It is cautious due to the dearth of proven results
on the longer term effects of prolonged applications on the
receiving lands. It is optimistic because of the scattered
shorter term examples which have demonstrated that under care-
fully controlled and managed conditions, wastewaters and sludges
can be recycled on selected sites without any apparent adverse
effects. We are aware of the benefits to be gained. The waste-
waters and sludges that are accepted for disposal have character-
istics that can enhance the soil environment for plant growth,
provided that the soil-plant system is not overloaded beyond
its capacity to assimilate the materials.
However, with some notable exceptions in the area of land
reclamation and rehabilitation, it is generally true that the
primary concern of the Forest Service at this time is more one
of aiding disposal with minimum detrimental impacts than
it is one of looking to onsite benefits. This is in support
of the established policy that Forest Service programs, wherever
possible, contribute to community development and to the
improvement of the rural environment in general.
FEDERAL ENVIRONMENTAL QUALITY REQUIREMENTS
All Forest Service policies concerning environmental quality
must be in line with policies determined at other levels. We
must be aware, therefore, of applicable policies set by the
President in his messages to Congress, Executive Orders and
Regulations issued in the Federal Register, Council of Environ-
mental Quality (CEQ), and the Environmental Protection Agency
(EPA), as well as our own Department of Agriculture (USDA). We
must also be aware of applicable State air, water, environmental
quality, and public health standards.
Executive Order 11514 of March 5, 1970, contains the following
statements:
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"Federal agencies shall initiate measures needed to direct
their policies, plans, and programs so as to meet environmental
goals:
a. Monitor, evaluate, and control on a continuing basis their
agencies' activities so as to protect and enhance the quality of
the environment.
b. Develop procedures to ensure the fullest practicable
provision of timely public information and understanding of
Federal plans and programs with environmental impact in order
to obtain the views of interested parties.
e. Review their agencies' statutory authority, adminis-
trative regulations ... to identify any deficiencies or in-
consistencies therein which prohibit or limit full compliance.
f. Foster investigations, studies, surveys regarding
ecosystems and environmental quality.
h. Promote development and use of indices and monitoring
systems to assess environmental conditions and trends.
k. Issue guidelines."
Executive Order 11507 of February 4, 1970, concerns prevention,
control, and abatement of air and water pollution at Federal
facilities. Among other things, it contains the following section
(46):
"In those cases where there are no air or water quality
standards as defined in section 2(d) of this order in force for
a particular geographic area or in those cases where more strigent
requirements are deemed advisable for Federal facilities, the
respective Secretary, in consultation with appropriate Federal,
State, inter-State, and local agencies, may issue regulations
establishing air or water quality standards for the purpose of
this order, including related schedules for implementation."
Another point of real significance is assigning head of
agencies primary responsibility for meeting operational and main-
tenance requirements in the Standards section. This includes
provisions for training of manpower. We are working with EPA
and other Federal agencies on training guidelines regarding
qualifications and performance for individuals involved with
environmental monitoring and surveillance and the continuing
review to ensure that requirements are being met. Also, in time
it is likely that we might be faced with certification require-
ments in the States where monitoring is located.
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The National Environmental Policy Act of 1969 (PL 91-190)
requires Environmental Statements on each proposed major Federal
action affecting the human environment. The statements must be
of sufficient detail to allow a responsible official to make
determination of the environmental impacts to be expected
from program implementation. Environmental values must be
weighed objectively with economic development and social well-
being goals over both the short and the long run. Also, taken in-
to account are the comments of other agencies, individuals, and
groups having interest in a project. This last item, consulta-
tion with other, is an essential consideration of the Act.
The Multiple Use-Sustained Yield Act of 1960 requires the
maintenance of productivity of the land to assume perpetual
optimum land . . . output of the various renewable resources.
The Code of Federal Regulations, Title 40, Part 35, with
interim regulations on pollution control that became effective
July 1, 1972, sets forth requirements for basin control water
quality management planning, adequacy of treatment, operation and
maintenance of wastewater treatment works for prevention, control,
and abatement of water pollution at Federal facilities.
The general objective of the Department of Agriculture is to
encourage land and water uses that will yield continuing maximum
benefits to the people of the United States. Adjustments in
land use to balance onsite and offsite needs should be made in
ways that will make land and water available to an expanding
population for living space, industry, commerce, and recreation.
The systematic use of proven soil and water conservation
techniques is encouraged to protect and develop land resources
for future uses, to manage the soil resource for human needs,
and protect and improve watersheds for both agricultural and
urban uses.
The Director of Science and Education in the Secretary's
Office of the USDA has stated that in connection with the possible
use of National Forest lands for sewage disposal and nutrient
recycling, any substance containing toxins in amounts specifically
banned from agricultural use by Federal law would not be per-
mitted for land application. This means general and local
standards and criteria for disposal of sewage on National Forest
lands must be developed to preclude environmental damages and un-
desirable ecological changes, and an effective monitoring system
would be mandatory to ensure compliance with standards. Too,
full coordination and cooperation will be maintained with EPA.
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LAND AND RESOURCE USE REQUIREMENTS ON NATIONAL FOREST LANDS
As with other "special uses," wastewater and/or sludge
disposal on National Forest lands by an out-Service group can
only be done under a special use permit. Permit requirements in-
clude plans for application, surveillance, and followup manage-
ment of the area. Sludges that have been stabilized by digestion
or some equivalent process are acceptable. Acceptable wastewaters
include those that have received primary and secondary treatment
plus chlorination to reduce the health hazards. Chlorinated
lagoon wastewater may be considered as equivalent to a secondary
treatment. Permits require compliance with applicable Federal,
State, and local environmental, public health, and water quality
laws and standards.
A land manager's decision to approve or disapprove an
application for wastewater disposal is based on the possibilities
of beneficial or adverse total environmental effects. Each
application for a permit requires, therefore, a study and an
analysis fo the environmental factors involved in relation to
the objectives and local land use demands of the area involved.
The methods and techniques for applying wastewater on forest
and rangelands must be in accord with practices which can be
publicly endorsed.
STATUS OF SPECIFIC POLICY DIRECTION
Forest Service national policy direction is gradually being
firmed and, naturally, at this stage is influenced by the ex-
perience and knowledge of many people and agencies.
It has been recognized that a combined effort within the
Forest Service will be needed to formulate a uniform and specific
policy direction to wastewater disposal. A strong supporting
research program is obviously essential and initial state-of-
the-art guidelines for sewage disposal on agricultural and forest
lands have been prepared by James 0. Evans of the Division of
Forest Environment Research of the U.S. Forest Service, Washing-
ton, D.C. Certain land use and management plans for the area
including required environmental quality surveillance will
require periodic updating.
The Eastern Region of the U.S. Forest Service has recently
issued a provisional guide entitled "Environmental Protection
Criteria for Disposal of Treated Sewage on Forest Lands." The
guide attempts to form a bridge between water quality standards
and soil quality standards and includes suggested criteria levels
that may ensure minimal hazard to environmental values. This
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guide was prepared by Hugh Cunningham, soil scientist, Monogahela
National Forest, and has proved to be a valuable document.
As mentioned previously, regulation of the disposal system
project must depend on a well-designed and implemented system of
monitoring (data collection) and the interpretation of these
data in terms of their meaning to total resource management on
and adjacent to the specific site. Many of the recently passed
laws and regulations pertaining to environmental values and
the reflections of public attitudes make it essential that we
document the effects of our management practices and activities
on the soil resource as well as on the air and water resources.
Physical, chemical, and biological characteristics and pro-
perties are all of concern.
Esthetics will also be provided for disposing of wastewater.
The basic character of the landscape should be maintained with
man-made alterations fitted to the immediate countryside.
Special attention will be given to harmoniously joining size,
shape, location, and dispersion of disposal sites so they respond
directly to visual characteristics--form, line, color, and texture-
of the surrounding landscape.
FUTURE OUTLOOK AND POTENTIAL IMPACTS
Because of use of land for wastewater and sludge disposal
places certain restrictions on other land uses, the selection of
satisfactory disposal sites is in turn restricted. At the present
time, we see the greatest opportunity for large-area disposal sites
on those lands upon which activities and uses are already
restrieted--surface mined areas (land restoration), firebreaks,
greenbelts, arid the like. These may not be the best sites for
this purpose, but widespread use of lands having greater potential
or capacity for disposal will depend largely on public acceptance.
This, we believe, will come gradually with better understanding
of ecosystem functioning and public involvement in the planning
efforts at all stages. Small-area disposal sites can and are
being located near the areas being serviced.
At the present time, there are 26 sites on National Forests
in 14 States involved in planning for land disposal of wastewater
and/or sludges by sprinkler or flood irrigation. We expect an
increasing number of applications for this type of use on National
Forest System land.
A word of prediction as to the future in the use and management
of wastes and resources on National Forest lands might be ap-
propriate in closing these remarks. The word is balance;
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balance between people's needs as reflected by demand and by
the capabilities and opportunities at hand for waste disposal
and utilization. The challenge of achieving balance is possible
through careful planning and management. We are making progress
toward this goal.
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SPRAY IRRIGATION - THE REGULATORY AGENCY VIEW
Richard C. Rhindress
Ground Water Quality Management Unit
Pennsylvania Department of Environmental Resources
The Bureau of Water Quality Management of the Pennsylvania
Department of Environmental Resources is the regulatory agency
concerned with the protection from pollution of all the waters
within the state. As such we have been aware of the growing
interest in the various techniques of land disposal for liquid
wastes for quite some time. The increasingly stringent waste
quality requirements for the discharge of waste water to streams,
coupled with the upgrading of requirements for waste water treat-
ment, plus the need for disposal in areas where streams are not
readily accessible, have increased the importance of land disposal
of liquid wastes. The point has been reached where it must be
dealt with squarely as one of the alternatives for the treatment
and ultimate disposal of waste water.
A regulatory agency becomes aware of spray irrigation from two
separate sources: 1] as a new technique being promoted, and 2) as
enforcement officials viewing a number of existing problems. As an
environmental protection agency we have an obligation to consider
all techniques of waste disposal and to assess their applicability
to various wastes and their impact upon the environment. The
problems which we recognized from the earliest days of our experience
with operating spray irrigation systems indicated that regulation
was needed. The imposition of regulation, however, carries with it
a responsibility to provide guidance in the construction and location
of such facilities so that the potential user can develop a plan
satisfactory to the regulatory agency. This paper will discuss the
experiences of our Department with spray irrigation, our philosophy
concerning the use of land disposal techniques, and some important
concepts which we have included in our Spray Irrigation Manual.
DEFINITIONS
At the outset of this paper on spray irrigation we should
decide exactly what we mean by spray irrigation. Under the general
classification "land disposal of liquid wastes" there have been a
number of confused interpretations as to what is spray irrigation.
I believe the definition should be, "the application of waste water
to the land surface for treatment and/or ultimate disposal, using
aerial dispersion (sprinklers) to distribute the effluent evenly
over the land surface".
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However, there are a number of other land application methods
which have been confused with (and one might say "passed off" as)
spray irrigation. These methods are mentioned here because we in
a regulatory agency have found that we must deal with all of them
as variations on a theme. For the most part they are significantly
different; they usually require different technologies, and differ-
ent site selection. One is the technique of spreading: driving a
tank truck across a field, letting the effluent spew from the open
valve, sometimes with the benefit of a spreading device. Another
variation is simply open pipe discharge to a land area, often down
a hillside. Third is the dumping of a sewage treatment plant
sludges and septic tank sludges onto the land surface, with or
without the benefit of spreading or burial. Several persons have
chosen to call the application of even these non-sprayable wastes
to the land surface a form of spray irrigation. Somewhat more akin
to classic spray irrigation is ridge and furrow irrigation, where
the effluent is spread through a series of shallow trenches. One
other technique is the use of surface flow, much on the idea of a
standard sand filter where the effluent is allowed to flood an area
of ground and slowly sink into it. None of these techniques are
equivalent to spray irrigation; however, to some extent they are
each valid techniques of land disposal for liquid wastes when
properly executed.
This paper will deal only with classic spray irrigation, the
aerial disposal of waste water using a system of sprinklers, piping,
and sprinkler nozzles.
STATUS AND REGULATION
Pennsylvania presently has 75 spray irrigation installations
in operation, and another 10 to 15 in planning and design stages.
The vast majority of these installations are relatively small,
serving a single industry or small sewage treatment plant. Most are
industrial waste applications. The largest number of these are in
southeastern Pennsylvania, primarily in the Great Valley or Piedmont.
Most of those which are presently under permit from the state have
their permits because they have had pollution problems in the past.
Although regulation has always been possible under the Pennsylvania
Clean Streams Law, a discharge to the land surface was not clearly
recognized as a discharge to the waters of the Commonwealth. It
was considered similarly to septic tank installations where the
interpretation was that there was no direct discharge, therefore,
no need for a permit. Spray irrigated water, of course, does dis-
charge to ground water by percolating down through the soils, over-
burden, and rocks to the water table. Thus it is definitely a
discharge to the waters of the Commonwealth as defined by the Clean
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Streams Law. A new program to bring all spray irrigation installa-
tions under permit will be implemented with the publication of our
spray irrigation manual and new regulations.
GROUNDWATER DISCHARGES
At the same time that spray irrigation was becoming more
prominent in Pennsylvania, we, like many other states, were becoming
increasingly aware of the need to protect the quality of groundwater.
Many septic systems are not, in fact, doing their job of renovating
waste completely before it reaches groundwater. Even the best sani-
tary landfills are recognized as sources of groundwater. Spray
irrigation presents itself as a new technique for the treatment and
ultimate disposal of waste water. It keeps waste water out of the
streams but in doing so poses a very real threat to the quality of
groundwater.
Unlike streams which can rebound from polluted conditions in
a few years, groundwater does not experience the flushing action of
stream flow. It does not experience the purifying effects of air,
light, and biological organisms. Instead it flows very slowly,
receives little dilution, has essentially no oxygen to degrade
pollutants, and flows through a medium where surface tension tends
to hold pollutants in contact with it.
The general public thinks that groundwater is clean, fresh and
pure, and available in that state wherever they may choose to drill
a well. Fortunately, for much of the state, groundwater has these
properties.
Although both the law and the public attitude demand that
.groundwater remain drinkable, the conditions under which ground-
water exists deny significant renovation. Therefore, our goal for
groundwater quality is that it be usable for domestic purposes with-
out treatment. It is imperative to preserve groundwater in its
purest possible state. The technique of spray irrigation poses a
very real threat of pollution.
Experience with the presently operating systems is generally
poor. Two basic problem areas have been defined: (1) improper
system design and (2) management errors.
Design Problems:
Design problems can be traced to several sources. Waste treat-
ment plant designers have had little or no education or experience
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with this new technology. Attempts have been made to design systems
without the understanding of the following basic tenets of spray
irrigation design: First, spray irrigation is only an alternative
method for disposal and treatment; Second, spray irrigation must
be integrated into the environment rather than imposed upon it; and
Third, as a dispersed operation, it will be far more difficult to
control and manage.
Spray irrigation, and land disposal, have been advocated as
the panacea for wastewater disposal problems. The literature has
been attractive and promising. Unfortunately, very little of the
literature speaks of potential problems and the limitations of such
a technique. Thus, the consulting engineer has often been given a
false sense of security. Any proposal to disperse wastes into the
environment must consider the multiple constraints that the environ-
ment will place upon it. It is only after a thorough consideration
of these constraints that the decision can be made that spray irri-
gation should be used alternatively to some other method of disposal,
such as direct discharge to a stream or groundwater. For example,
one agricultural waste was applied to a field for a number of years
until eventually the soils were so altered that infiltration and
percolation of the water was converted entirely to sheet runoff.
The fields were entirely ruined and will be long in recovery. The
loss of these agricultural lands and the degradation of groundwater
in the area has forced the industry into acquiring both new lands
and more expensive water source. In this case, it would have been
far better to construct a direct pipeline to discharge to a creek
over a mile away, or so treat the waste that the soil could accept
it.
When using the "living filter" for waste renovation, it is
extremely important that the whole wastewater treatment and disposal
system be matched to the environmental capabilities rather than
impressed upon it. The simple addition of the extra hydraulic
load will be a major stress on the system. Further, the require-
ment that the soil system act as a treatment facility in decaying
and renovating the waste is an added stress. Most natural areas
are in a state of dynamic equilibrium. This dynamic equilibrium
has the ability to respond to passing stresses. However, when a
stress is applied uniformly over long periods of time, equilibrium
of the ecosystem is severly altered and may, in fact, be destroyed.
For example, a soil with a fragipan layer will have a low perme-
ability, and be capable only of accepting infiltrating water at
normal precipitation rates. Dosages much above this result in
waterlogged soils and runoff or swampiness. A second example:
vegetative communities are adapted to a soil and its available
moisture capacity. However, when spray irrigation applies a hydrau-
lic stress the vegetative system must adapt with the disappearance
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of some species and introduction of others. In addition, streams
below the site will have to adapt to a different flow regimen with
a different chemical quality. All this is not necessarily bad,
although in all but one of our experiences it has been. There are
a few cases where environmental improvement may be realized through
the stressing of the natural system. The assessment of the natural
system, and the strains which it may show as the result of the new
stresses are the prime subject matter of the Department's Spray
Irrigation Manual.
For several reasons, lack of control has been a major problem
in the design of spray irrigation systems. Consultants have
usually ignored the valuable assistance available from the agri-
cultural irrigation industry and have pieced together a system of
pipes and valves from a catalog. Agricultural irrigation systems
are designed simply to get water to a field. There is little
concern about loss and leakage until it becomes a major problem.
Agricultural systems are designed for ease of mobility and minimum
maintenance. They are also used primarily for a short season.
Conversely, wastewater irrigation systems are generally to be used
year-round, must be watertight, should rarely be moved or moved only
in conjunction with a carefully designed plan, and should be con-
sidered part of a long-term investment and installation. Also, in
the agricultural sense the irrigation system is part of the profit-
making package. It is carried on the profit side of the ledger
books, whereas a waste disposal system is usually considered as a
liability - as something that must be done - but which is not
important to the success of the operation. Thus it is rarely ade-
quately budgeted. Further, it is usually located at a considerable
distance from the plant and the base of company operations. Often,
it is completely out of sight. Thus routine operations such as
checking for blockages and turning valves to change irrigated
sections of the field are often neglected or relegated to a minor
priority in company operations. Thus the need for mechanical,
electrical, or computer control of the operations becomes very
important to successful continued routine operations. Automation
of the controls has been entirely neglected at the majority of
sites.
With any new technique, there is the problem of education
regarding its values and execution. Poor design of the spray
irrigation systems presently in existence is due to the unfamil-
iarity of the design consultants with a new technique, and the
technologies and equipment necessary to carry it out. Training
courses and symposia are needed to fill this educational hiatus.
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Management Problems:
As mentioned above, management and maintenance are a second
major problem area for spray irrigation fields. Management views
spray irrigation, or any waste discharge area, as a liability to
firm operation and therefore consistently relegates its consider-
ation to a very low priority. Maintenance of a spray field is
normally the responsibility of the bottom man on the maintenance
staff. He, of course, is usually the man called upon to fill in
whenever there is another important task to be done or when other
employees may be absent. Spray fields can go unattended for con-
siderable periods of time without causing a problem. A well
operated spray field may, in fact, go for many months without
appreciable maintenance problems. However, a single malfunction
within the system can stress the ecosystem to its irreversible
limit. Thus, it is important to have maintenance overseeing the
field on a routine basis. Unfortunately, the usual experience in
Pennsylvania has been that when inspectors inspect the site, they
find evidence that no one has viewed the field or cared to make
necessary repairs for quite some time.
Some common problems are contained in the following list:
1. Broken pipe
2. Leaky joints
3. Vegetation blocking sprinklers
4. Valves and/or sprinklers corroded in position
5. Rutted areas from vehicular traffic in wet soils
6. Clogged sprayers
7. Unharvested vegetation
8. Swampy conditions with ponding, with even aquatic flora
and fauna
9. Vector problems - flies, mosquitoes and rats
10. Anaerobic soil conditions producing swamp gases and other
foul odors
11. Sheet runoff directly to adjacent streams
12. Waste material build-ups which inhibit plant growth -
solids and greases.
The above are quite common. In addition to these we find
evidence of application of wastes which are entirely non-degradable
by the living filter system. These usually are toxic and stress
the field beyond recovery.
SOLUTIONS
The solutions to the problems with spray irrigation can come
from three levels: the designer, the management, and the regulatory
agency.
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Design Solutions:
The primary solution for the problem of securing adequate
designs is one of education. Engineering schools will have to
recognize spray irrigation and other techniques of land disposal as
valid waste management alternatives to be included in the curricula.
For the continuing education of the graduate designer, the state
regulatory agencies and professional societies will need to provide
data and information on the new techniques. For the consultant, it
is imperative at this time to go to those who have had experience
both in the experimental development phases of land disposal and in
the regulatory phases, and to learn from their experience. In
addition, he should rely heavily upon the expertise available from
the irrigation industry.
The following fifteen steps in the implementation of a spray
irrigation installation were compiled by Lewis W. Barton, a spray
irrigation consultant from Cherry Hill, New Jersey, and the author.
They should serve as guidelines to anyone considering land disposal
of liquid waste.
1. Before deciding on land disposal or spray irrigation,
examine all the alternatives regardless of any apparent
restrictions. Consider recycling of wastewater and direct
discharge of treated wastes to a stream or to groundwater.
2. Weigh the motives for using land disposal. Is the desired
result groundwater recharge? Agricultural irrigation?
Green belt irrigation for fire protection? Or just plain
final treatment and ultimate disposal? Or some combination?
3. Make a preliminary tour of the area (not just the site)
with reference to suitable land, a route for the force
main, sites for any pumping stations, field drainage, and
lagoons for storage and flow equalization.
4. Study the effluent characteristics in detail. Assess
their biodegradability by the living filter. Determine if
any inorganics may be present which will not be removed by
the soil system or which will poison the environment.
5. Select a site. Choose the best site available. Work with
the local real estate man for an option or a lease. Work
with hydrogeologist and a soil scientist in making this
preliminary site selection. If there is any doubt about
the acceptability of the land for spray irrigation use,
negotiate options or leases on double and amount of land
that you expect to use.
6. Map the selected site, showing contours, topography, soils,
geologic structures, bedrock geology, streams, springs,
wells, woodland areas, existing buildings, and present
land use patterns for the designated acreage.
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7. Choose sites for background and down-gradient groundwater
quality monitoring.
8. Draft a preliminary proposal to the state regulatory agency
which includes the above data and a preliminary approval
before proceeding with detailed design and further financial
commitments.
9. Design the piping system, force main, and drainage; specify
the hardware, field preparation, seeding, fertilizing, and
agricultural maintenance.
10. Design and specify the automated programmers which will
provide the central operating system, including pump
signals and malfunction alarms.
11. Prepare and present the appropriate applications to regula-
tory agencies.
12. Bid the project and supervise construction. Establish and
sample groundwater monitoring points before any other
construction proceeds.
13. Prepare an operating manual that is simple and easy to
follow. The operating manual is one of the most important
pieces of the design engineer's task. It is also probably
the most often neglected.
14. The design consultant should include in his contract
monthly inspections of the operation for at least the first
year. These inspections should involve the consultant,
management, the operator, and the regulatory agency.
IS. Conduct quarterly inspecting through at least the second
year and even into the fourth and fifth year. These
inspections will provide for continuing surveillance of
system efficiency as well as for keeping the facility out
of trouble with the regulatory agency.
Management Solutions:
From the management point of view the main steps which can be
taken are the following:
1. Responsibility for spray field maintenance should be a
full-time position. Interviews with a number of mainten-
ance personnel have indicated that they consider their
job a full-time project. Many have even suggested that
we confer with management to help convince them of the
amount of work necessary to keep a spray field functioning
properly.
2. Put the effluent to some good use rather than just dispos-
ing of it; i.e., use it for irrigation where it will be
an integral part of company operations.
3. Maintain a schedule "of routine inspections.
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Wherever possible install a buried or permanently set
system. Experience has shown that movable systems either
do not get moved or suffer from severe wear and tear.
Do not try to overload the system as production increases.
Redesign or add to the system.
Regulatory Solutions:
Under present Pennsylvania law, the operator of a spray
irrigation system which is disposing of sewage is required to
obtain a certificate for sewage treatment plant operation. As
another step in solving problems with spray irrigation systems, the
state may have to extend certification to all spray field operators.
In fact, it may be desirable to make "Spray Irrigation Field Oper-
ation" one of the classes of certification. Certification of spray
field operators would give the regulatory agencies a stronger lever
for improved operations, as withdrawal of the certificate for
improper operation of the facility could put the operator out of
work and place his company in violation of the law for not having
a certified operator. The present condition of many spray fields
within the Commonwealth suggest that this is a very likely path to
follow. Again, the state has an obligation to provide information
for training for spray field operator certification.
Other regulatory solutions include normal enforcement activity,
design review and permitting, and the issuance of regulations and
design standards.
PENNSYLVANIA'S SPRAY IRRIGATION MANUAL
The fast rising number of spray irrigation installations and
applications indicate that the Department of Environmental Resources
should publish a manual or set of guidelines to site selection and
system design. The manual would also include instructions for the
preparation of plans and reports for securing a permit. The manual
has been published as the "Spray Irrigation Manual", Bureau of Water
Quality Management Publication No. 31, and is available from the
Bureau, located in the Fulton National Building, Third and Locust
Streets, P. 0. Box 2063, Harrisburg, Pennsylvania 17120.
Such a manual is necessarily written for a wide audience. It
speaks to the consulting engineer and designer, the hydrogeologist
and soil scientist. It also speaks to corporate management which
may desire a spray irrigation system, and it often speaks to local
officials and the land owner who knows very little of the technology
or responsibilities involved. In speaking to a wide audience it is
both an educational tool and somewhat of a design manual.
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Writing a design manual is not entirely feasible since one of
the main tenets of spray irrigation is that the system must be
integrated into the environment rather than imposed upon it. And
since the environment is extremely variable with the respect to
groundwater, soils, geology, agriculture, and climate across the
state, it is impossible to write a design book for all the possible
variations in the environment. The assessment of these variations
in the natural environment is what the manual is about. It speaks
of concepts and their importance, and how each of them relates to
the spray irrigation techniques of land disposal.
Basic criteria for spray irrigation have been set as a base-
line from which judgement as to the acceptability of a site can be
related. First, we insist that the entire waste handling package
must be considered together: the pre-treatment, the storage, flow
regulation, and the irrigation system. We emphasize that spray
irrigation installations may be utilized only where the wastewater
contains pollutants of such type and concentration that they can
be satisfactorily treated through distribution to the soil mantle.
Generally, only biodegradable wastes are acceptable, and the equiv-
alent of secondary treatment must precede spray irrigation.
However, we do allow for variability in earth materials, spray
field use, and effluent constituents by stating that treatment
requirements and performance criteria will have to be determined on
a site-by-site basis. The prime consideration for site selection
is the ability of the organic and earth materials to properly treat
the waste.
One item which has caused considerable difficulty in drafting
the spray irrigation manual has also proven to be a cause of much
misunderstanding on the part of manual users. A large number of
potential users for spray irrigation are industrial waste genera-
tors. These various firms will want to place a wide variety of
biodegradable and non-degradable waste on their fields. Because
of the wide latitude in constituents and concentrations it would
be impossible to write a spray irrigation manual which tries to
speak to each of these possible wastes. It is far more practical
to write a manual which is oriented toward the spray irrigation
of sewage. Considerations of industrial wastes must then be made
as they compare to sewage. Flows and concentrations are calculated
and adjusted as percentages of normal sewage effluent.
Manual Organization
The remainder of this paper will review important points and
concepts in the Pennsylvania Spray Irrigation Manual, with a dis-
cussion of the reasoning behind some of the more important ones.
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1. Certain criteria have been stated for the pretreatment. of
waste, application rates, acceptability of soils, agricultural
practices, etc. These criteria have been set primarily as guide-
lines based upon spray irrigation of sewage effluent. However,
throughout the manual there are numerous statements which demon-
strate our intention to be flexible and willing to consider special
applications and experimental designs. Although a number of spray
irrigation sites have been in existence throughout the country for
many years, they have not benefited from a total environmental
impact study before implementation and have usually ended in some
form of pollution. The lessons we have learned from them have been
mostly negative--what not to do. Thus, we feel that this technique
is still in the developmental stage and we are willing to permit
justifiable experiments which vary from the basic criteria.
2. For most water pollution control facilities, construction-
ready plans are required with the permit application. But, because
of the need for land purchasing and extensive testing and drilling
programs to determine and subsurface geology and hydrology of the
spray field, the Department has instituted the preliminary review
to determine the general acceptability of the proposed fields before
capital investments or detailed designs are made. For a preliminary
review the applicant submits:
a. A short statement of the nature of the project and
wasteload characteristics; information on location,
soils and climatology.
b. Preliminary spray field design and operation plans.
If the Department grants preliminary approval of the spray fields,
the applicant is notified and the complete permit application is
then submitted. The preliminary approval does not approve the
construction or operation, nor does it assure approval of the
complete design report. Issuance of the Department of Environ-
mental Resources permit must precede construction and operation.
3. Factors for Consideration: A large section of the manual
is devoted to some detailed explanations of factors that must be
considered as they affect the renovation of the wastewater and its
movement to groundwater. We are very concerned that the best soils
and geologic and hydrologic conditions are available for these
processes, because once the wastewater reaches the water table only
minimal renovation of the waste can be expected. Thus, extreme
care must be exercised in assessing these environmental factors.
a. Earth Materials: The earth materials at a spray
irrigation site may consist of soil, unconsolidated
surficial deposits, weathered rock, and bedrock. In-
filtrating wastewater will pass through these materials
430
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as it percolates to the water table. The earth
materials near the land surface serve as a substrate
for biological activity, while the unconsolidated
materials must be such that a direct rapid movement
(short circuit) of the irrigated water to the ground-
water does not occur. Coarse sands and gravels, open
fractures in bedrock, and shallow soils are all
examples of conditions which may result in short
circuits. The earth materials should be moderately
permeable and of a uniform quality so that they will
provide slow but continuous downward movement of the
infiltrating wastewater, yielding an adequate residence
time for renovative reactions to take place. Detailed
information on the geology, soils, and hydrology.
b. SoiIs: In addition to meeting the various textural
criteria, we urge that during the preparation of the
field and installation of the equipment, particular
attention be paid to avoiding disruption of the estab-
lished soil profile as much as possible. Recommended
application rates are based on the drainage and per-
meability of the soil, available moisture capacity,
and the depth to the water table.
c< Geology: Once the irrigated wastewater leaves the
soil zone and enters the zone of weathered and fresh
bedrock, it is particularly important to know the
structure of this rock. Are fractures present which
will short-circuit the water directly to the water
table or route it preferentially in directions which
modify its assumed direct route to the water table?
Will the waste react with the rock? The geology also
affects the direction of movement within the water
table as it flows through and away from the site.
d. Hydrology: Under most conditions in Pennsylvania,
spray irrigated wastewater will recharge the local
groundwater. With pretreatment, adequate dispersal
of the waste, and properly chosen earth materials,
the wastewater should be adequately treated during its
passage through the zone of aeration to the water
table. Thus, pollution of the receiving groundwater
will be prevented. But once the wastewater reaches
the water table only minimal renovation can be expect-
ed. Thus, to insure that the applicant has considered
groundwater, its movement, and the potential result
of its contamination, we have required that monitoring
facilities be placed beneath the site and in all
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directions of groundwater flow away from the site.
In addition, a background water quality well must be
established where the quality of water flowing into
the area may be assessed for comparison. A secondary
benefit to monitoring is that the data provide a
valuable tool to the operator in limiting potential
legal action from nearby groundwater users. These
legal actions often are the result of fear and
ignorance, thus the acquisition and maintenance of
background and discharge data is imperative to the
operator. This data also provides the regulatory
agency with data for evaluating the efficiency of
the operation. The submission of routine (generally,
quarterly) reports of water quality data from both
background and downgradient monitoring points is
required. The exact chemicals that are reported are
dependent upon the waste. For sewage, routine reports
would include phosphate, ammonia-nitrogen, nitrate-
nitrogen and MBAS.
e. Agricultural Practice: Although the Department has no
specific requirements as to agricultural practice,
other than the maintenance of the vegetative cover on
the field, we recommend that the agricultural manage-
ment coordinate closely with slopes of the field and
the excess hydrologic loads. Research projects such
as the one at Penn State University have demonstrated
that agricultural product yield can be significantly
improved using spray irrigation. Yet, relatively few
farmers have been willing to accept the long-term
commitment to use the wastewater that is necessary to
implement a system. Self-serving industry systems
apparently are working. But for municipal sewage
systems, this raises the questions of the applicability
of funding to the purchase or rental of spray fields,
the desire of the community to get into agricultural
land management, and an educational problem of con-
vincing would be lessees of the value of a long-term
commitment.
f- Itesearch: As stated above, existing spray irrigation
facilities have demonstrated that the technique has
not been adequately planned or managed in the past.
Certain research facilities and a few showplace oper-
ations have demonstrated the value of spray irrigation
both for wastewater treatment and disposal, and as an
agricultural benefit. However, these projects have
been limited in their scope and in the geographic
diversity. There is an immediate need to expand
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research and demonstration projects to soils and
environments which are less ideal than these research
installations. New environmental constraints must be
tested, and engineering techniques of field prepara-
tion and modification should be considered. We can
integrate spray irrigation into a natural system and
we can learn through applied research how this inte-
gration can take place, but spray irrigation cannot be
impressed upon natural systems.
SUMMARY
Like all rapidly developing technologies waste treatment and
disposal by spray irrigation has suffered from misunderstanding,
inadequate design, mismanagement, and misapplication. Conversely
it shows great promise as a valuable alternative technique for waste
water management. New research and regulatory action will help, but
a new attitude of environmental understanding is necessary by all
potential users. The key to this understanding is the acceptance
of the basic tenet that spray irrigation must be integrated into
the environment rather than imposed upon it.
DISCUSSION
Unknown: Is your experience on these spray irrigation systems
any worse or better than the typical treatment plant?
Rhindress: Unfortunately I can't even discuss that because I have
been strictly dealing with this as a geologist. I
guess I'll have to turn it over to one of our other
staff members, if they want to comment. These systems,
however, are almost uniformly poor.
Reed: I would like to know where we are training this
maintenance personnel.
Rhindress: We're not. It's something that we've got to get working
on and get working on fast.
Hall: I notice in your manual the statement that under usual
conditions the ground water mound should be built up
and should not reach within 10 feet of the ground
surface. It seems from other discussion that I've
heard here that this is a pretty difficult limitation.
Do you find it that way or not?
Rhindress: It hasn't been. The manual was just published, so it
hasn't been really a criteria for long. That criteria
is based on some experiences, one of which is poor
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operation. We're being very conservative. Another
thing is that we feel and have felt through experience
and reading the results of research that we needed a
large zone of aeration. We felt that 10 feet would be
adequate. We're learning more on this all the time.
We felt at the time of writing the manual that 10
feet would be a good level in terms of a safety zone
and that needed for the zone aeration.
Williams: I can't let that pass. Your rationale for a 10-foot
zone escapes me completely. Why do we need 10 feet of
aerated soil? What good does it do? Why not 20 feet
or why not 2 inches? This is the groundwater mound
when you are operating. This is not the normal ground-
water table that you're talking about.
Rhindress: Right. One thing that I must point out and you've
apparently not read the manual to this point, practi-
cally every value in there has a statement ahead of it
or behind it or near it that says this is recommended.
We can and will allow practically anything if we can
be shown that there is reasonable evidence to believe
that it will work. This is a guideline not a set of
criteria. As I said earlier, state specifications are
not going to be written. They can't be written.
Kardos: But the trouble occurs when you put out a guideline like
this and it gets into the hands of engineers. They look
at these as state specifications because there are
inferences that this is what you're thinking of and if
you put in a plan that deviates from that you're going
to have trouble getting it approved.
Ifoindress: All I can say is if I'm reviewing the plan, they won't
have any trouble. I'll try my best to give the plan a
fair review.
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RESEARCH NEEDS -- LAND DISPOSAL OF MUNICIPAL SEWAGE WASTES
James 0. Evans
Forest Service, USDA
Washington, D. C.
This has been a very stimulating symposium -- probably the best
and most informative of its kind ever conducted. In fact, we have
made the first comprehensive attempt I know of to evaluate overall
problems relating to the application of treated sewage effluent
and sludge to forest, range, and agricultural land. We can be
certain that this will not be the final such venture. At this
point it seems appropriate to inquire why have we gathered here?
We also might reflect on what we have learned and consider
where we should go during the weeks immediately following this
symposium.
ASSESSMENT OF THE SITUATION
We are here because of a need --a need to determine the best
methods of handling a residue problem which literally is our own
creation. Most certainly the first man practiced land disposal,
but gave no thought to pretreatment. Looking back, as Adam's
children multiplied and assembled in communities, often the
disposal situation became a bit messy. Sometimes streams were
used to flush away the problem --a practice that worked rather
well as long as there was no overloading and other personal stream
uses were limited either to upstream areas or to sites at sufficient
distances downstream.
As our numbers continued to grow and congregate, through
necessity we became wiser and eventually developed an impressive
array of treatment-disposal facilities, some simple, other complex,
and some highly advanced technically. But none of our treatment-
disposal methods has proven wholly adequate. Often one kind of
pollution has been replaced by another, treatment-disposal costs
are increasing, sophisticated methods of disposal by discharge to
and dilution in air or water have become commonplace, and regardless
of the treatment method used, some residue always remains for ulti-
mate disposal. Potential resources have either been destroyed,
wasted, unused, or discharged to sites subjecting them to inde-
sirable enrichment and environmental change.
Today our natural environment is under savage assault. Waste
products of our accelerating technological development and expanding
population are rapidly becoming our most insidious and deadly
435
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enemies. A special report prepared several years ago for the
Senate Committee on Interior and Insular Affairs states:
The challenge is the rapid deterioration of the environmental
base, natural and manmade, which is the indispensable founda-
tion of American security, welfare, and prosperity ....
It is becoming apparent that we cannot continue to enjoy
the benefits of our productive economy unless we bring its
harmful side effects under control.
Thoughtful Americans will agree that there is but one answer:
Quality of the environment must be restored and preserved. The
cost will be high -- both in money and in effort. But the costs
of environmental pollution are even higher.
Each day in the United States about 100 billion liters (over
26 billion gallons) of sewage wastewater and roughly 10,000 metric
tons (11,000 short tons) of dry sludge solids are produced
(Evans and Sopper, 1972; Rosenkranz, 1972). Unfortunately all but
a small percentage of the nutrient-rich sewage effluents are
discharged into the Nation's streams. Sludge is currently dis-
posed as follows: 15 percent in the oceans; 25 percent by in-
cineration; and a perhaps surprising 60 percent by land application
(Rosenkranz, 1972). Included in this 60 percent portion are
(a) liquid sludge applied as a fertilizer, (b) sludge solids
applied as a combination soil conditioner-fertilizer, and (c)
sludge buried in landfills.
This symposium has dealt with the matter of recycling municipal
sewage wastes by land disposal. We have considered sewage wastes
not as refuse, but as useful resources (Evans, 1970). I am certain
that each of us knows more now about recycling sewage wastes
that he did when he arrived; however, all questions have not yet
been answered, and a few nagging new ones may have been uncovered.
What research is needed to perfect the use of this so-called
new resource? Fortunately, we have a good base upon which to build
sound research programs. This fact has been amply demonstrated
at this symposium which has produced some excellent papers and
provided much useful information about this rediscovered resource.
NEEDED -- A RATIONAL RESEARCH PROGRAM ON RESOURCE RECYCLING
The development of a rational recycling program in an inte-
grated, comprehensive manner requires an almost infinite knowledge
about the recycling process and ecosystem response. At the present
time we know very little about either.
436
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We must expand research on basic ecosystem function. Stevens
et al,_(1972) have recommended using interdisciplinary teams of
KbTogical, physical, and social scientists to test and analyze
large-scale, controlled, environmental manipulations. Land
disposal techniques and utilization of sewage effluents and sludges
would be included in these manipulations.
Use of open-space land areas for sewage disposal invites
consequent and perhaps undesirable ecological change. Foremost,
studies must involve understanding the ecology of open-space lands
and natural areas. Studies and evaluations should also be made
concerning emerging social patterns, viable economic units, trans-
portation and mobility, innovative technological advancements, and
physical and biological interactions among components of total
communities.
All subjects, including those selected for research, must be
visualized as occurring within one large area representing the
ecosystem. Land disposal of municipal sewage wastes can be
depicted as a small circle connected to other circles of similar
dimensions and all located within the larger Ecosystem Circle.
You may say that all this is fine, but our finances and cur-
rent knowledge will not allow implementation of grandiose schemes.
Let us be practical and realistic. What should we do now? Where
do we begin?
Following are specific research needs which should and can
be investigated now:
BMEDIATE RESEARCH NEEDS
1. The mechanics for efficient and effective handling of sewage
wastes and their disposal on various land areas must be developed.
Research is currently underway at Beltsville, Maryland, on the
comparative merits of incorporating sludge into soils by burial in
trenchs at depths of 2 and 4 feet, by deep disking, by rotary
tilling, and through other methods. Each of these methods should
be compared with various types of aerial spray mechanisms, surface
spreading techniques, and subsod or subsoil injection processes.
2. Economic factors relative to various or alternative handling
and disposal methods require investigation and evaluation.
3. Although technical solutions to waste-management problems
either already exist or can be found without undue effort, answers
are also needed to many problems having their roots in the social,
economic, legal, and political areas. Existing conditions and
437
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potential developments in the following areas urgently require
investigation: (a) esthetics and public acceptance, (b) compara-
tive costs, (c) competing needs and legal aspects, and (d)
political implications and trade-offs.
4. It has often been stated that major soil types or bench-
mark soils throughout the Nation need study with respect to their
ability to absorb, assimilate, degrade, adsorb, transmit, alter,
and store various organic and inorganic substances present in
sewage effluents and sludges. Hill (1972) has determined that
several soils occurring extensively in Connecticut exhibit vast
differences in permeability to, and capacity for removing ions
from, a synthetic sewage effluent. Considerable research is needed
on the interactions between various soil types and applied wastes
so that major soil groups can be evaluated and rated according
to their disposal capability.
5. Transport methods and costs, from sewage source to dis-
posal site or nearby holding area, can play a decisive role in
determining the feasibility of a sewage disposal program. They
need thorough study and evaluation.
6. Determination of the role of microorganisms in the
functioning of natural communities is needed. Also the ability of
key soil microorganisms to degrade, stabilize, and render
sewage wastes innocuous, and conversely, the impact of the wastes
or pollutants on the microorganisms must be determined.
7. Counteraction or reaction between applied wastes and soil
insect and small macroanimal populations should be observed and
evaluated.
8. Research should be geared to ascertain the degree of ulti-
mate disposal achieved. Many current pollution-abatement technologies
achieve little more than sophisticated dilution of sewage wastes.
9. Potential health hazards due to disposal practices require
urgent, careful, and extensive investigation:
(a) Unanswered questions have arisen concerning the potential
of harm to humans from toxins or pathogens in aerosols produced by
aerial spray application of sewage effluent.
(b) Possible health hazards arising from sludge spreading
must be evaluated and resolved. This means ascertaining the chance
of pathogen transfer to susceptible hosts as a function of time
since spreading and previous treatment of the sludge. It should
also include assessment of possible toxic substances in plants grown
on sludge-treated areas, such as nitrate in certain vegetables.
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(c) We must develop improved alternatives or refine
current treatments for sludge which will eliminate health hazards
posed by pathogens, nitrates, and other toxic substances.
Pasteurization is one technique of likely feasibility for elimina-
tion of pathogens. Aerobic treatment followed by anaerobic
treatment, or the oxidation-reduction process, is a very promising
technique for reducing the nitrate hazard.
(d) We must develop alternative treatments in effluent
disposal to eliminate health hazards from nitrates and other toxic
substances. Here again, the oxidation-reduction process has given
promising results.
10. We need to devise superior techniques for irrigating
effluent and spreading sludge beneficially on forested land. Such
development should be particularly useful in the industrial East
and to some extent in the Seattle -- Portland belt of the Pacific
Northwest, as well as in other Pacific Coast forestland and brush-
land areas.
11. We should determine long-term effects of various sludges
on appropriate land areas. Sludges should include: (a) con-
ventional digested sludge from domestic sources, (b) chemically
stabilized sludge (lime to pH 11, etc.), and (c) sludges from
industries (food, paper, textile, forest products, petroleum,
etc.) which do not contribute toxic quantities of heavy metals.
Appropriate land areas include: (a) pasture, (b) plowed land,
(c) orchards, (d) abandoned farmland, (e) forests, (f) deserts,
(g) rangeland, (h) taiga and tundra, and (i) mine spoil and other
disrupted soils. The effects include vegetation changes and runoff
and groundwater quality as a function of dosage.
12. Assessment must be made of the tolerance of crops and
forests to various heavy metals deposited with organic sewage
sludges, that is, organic sludges which reduce the toxicity of te
these metals.
13. We should make a thorough assessment of specific tree and
agronomic crop growth responses to various effluent and sludge
applications.
14. We should determine the quantity and quality of groundwater
recharge from effluent irrigation under various situations.
15. We need to determine the methodology for, and efficiency
of, effluent and sludge recycling in areas that remain frozen over
extended periods of time.
16. We must develop technically superior, better integrated,
and more comprehensive environmental monitoring systems.
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17. There is an urgent need for specific comprehensive
research, including the research listed above, to establish ade-
quate standards and guidelines for the use of sewage effluent as
irrigation-fertilization and aquifer recharge water -- and of
sewage sludge as a fertilizer and soil conditioner.
18. Research is needed on the possibility of toxic conditions
developing in certain plants resulting from excessive phosphate
accumulations in soils.
19. And finally, we must consider odor problems. Wherever
or whenever odor problems are apt to occur, they must either be
prevented, eliminated, or effectively controlled.
One could itemize additional urgent research needs but per-
haps a halt to a listing of particular research needs should be
made at this point. Before closing, however, I wish to further
emphasize that, whenever feasible, in our research planning we
must make a habit of taking the broader, and may I suggest
more ecological, view. To illustrate this approach, I have outlined
an elementary systein analysis to the recycling and utilization of
wastes in general by' land application. The illustration,
Recycling and Utilization of Biodegradable Wastes by Land Applica-
tion (Figure 1), is an adaptation and extension of a schematic
display devised by Besley and Reed (1972). The display is enlarged
to include waste effluents and forest and rangeland disposal sites.
The authors refer pointedly to the coranon practice in Europe and the
Far East of recycling biodegradable wastes to the land. They note
the considerable amount of reluctance to use human sewage in this
country and the more convenient and economical practice of using less
bulky and plant-nutrient-balanced commercial fertilizers.
Through research we can determine whether it really is more
economical on both a short-term and a long-term basis to use
commercial fertilizers exclusively, rather than sewage wastes.
I say exclusively because there just are not enough sewage wastes
produced in America to meet the farm fertilizer demands. Also,
through research we will discover much more convenient methods of
applying sewage nutrients than are currently known.
At this symposium we have taken a good look at land disposal as
a possible solution to our municipal sewage wastes problem. Few,
if any, of us came here thinking of land disposal as a panaceas.
Certainly, what has transpired here underlines many of the problems
and hazards as well as the benefits.
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INPUTS
/"
WASTES
Human Sewage
Septic tank
1
^^
Sewage effluent & sludge
Livestock. Poultry. & Fish
Agricultural and Forestry
Cannery
Dairy
Paper and pulp
Industrial
Organic
Selected inorganic
Household
— - —
BIOLOGICAL
SYSTEMS
SITES
Disturbed Land
Landfill cover
-plus — *- 1
Strip mines
Eroded, degraded land
"Sterile" sands
Old gravel pits
Clay pits
Productive Land
Agricultural
Forest
Range
(greenbelts)
Recreational Land
Parks
Game preserves
Other
MAN'S
FECHNIQUES
— yields — **-
IMPROVED
ENVIRONMENT
Conventional Farm
Management
Plow- Fu rrow-Cover
Sub-Sod Injection
Composting
Irrigation—
Spray-sprinkler
Rood- furrow
Surface Spreading.
Crops
Forests
Range
Livestock
Game
Fish Farms
Recreation
Green Acres
Parks
Conservation
Soil
Water
Air
Fig. 1. Recycling and Utilization of Biodegradable Wastes by Land Application
-------
REFERENCES
Besley, H. E. and C. H. Reed. 1972. Urban wastes management,
Jour, of Environmental Quality, 1(1), 78-81.
Evans, J. 0.1970. The soil as a resource renovator, Environ-
mental Science and Technology, 4(9), 732-735.
Evans, J. 0. and W. E. Sopper.1972. Forest areas for disposal
of municipal agricultural, and industrial wastes, Unpub-
lished paper to be presented at the Seventh World Forestry
Congress, Buenos Aires, Argentina, October 4-18.
Hill, D. E. 1972. Wastewater renovation in Connecticut soils,
Jour, of Environmental Quality, 1(2), 163-167.
Rosenkranz, W. A. WJT. Unpublished data presented at OST Spring
Review Meeting, April 21, Data prepared by Municipal
Technology Branch, Division of Research, Environmental
Protection Agency, Washington, D. C.
Stevens, H. K., Bahr, T. G., and R. A. Cole. 1972. Recycling and
ecosystem response, The Institute of Water Research, Michigan
State University, East Lansing, Michigan, 124 p.
442
-------
SYMPOSIUM ON RECYCLING TREATED MUNICIPAL WASTEWATER AND SLUDGE
THROUGH FOREST AND CROPLAND
LIST OF PARTICIPANTS
Abel, George A.
Environmental Protection Agency
1200 Sexth Avenue
Seattle, Washington 98100
Adams, Lowell
Environmental Resources Association
P.O. Box 2259
Monterey, California 93940
Alaisa, Comelio
Dept. of Water Resources Admin.
State of Md., State Office Bldg.
Annapolis, Maryland 21401
Ariail, J. David
Environmental Protection Agency
1421 Peachtree Street, N. E.
Atlanta, Georgia 30309
Askins, William
Pope, Evans, and Robbins
HE. 36th Street
New York, New York 10016
Bagnulo, Aldo H.
N. Va. Planning District Commission
7309 Arlington Boulevard
Falls Church, Virginia 22042
Amoroso, Edward Ball, Robert C.
Pa. Dept. of Environmental Resources Michigan State University
P.O. Box 1467 Institute of Water Research
Harrisburg, Pennsylvania 17120 East Lansing, Michigan 48823
Anderson, Donald F.
E.P.A., Tech. Division Office
1901 N. Fort Myer Drive
Arlington, Virginia 22209
Anderson, Robert
West Virginia University
Room 1132 Ag. Sciences Building
Morgantown, West Virginia 26330
Andreoli, Aldo
Suffolk County Health Department
County Center
Riverhead, New York 11901
Apgar, Mike
Roy F. Weston, Inc.
Lewis Lane
West Chester, Pennsylvania
19380
Bahr, Thomas
Michigan State University
Institute of Water Research
334 Natural Resources Building
East Lansing, Michigan 48823
Barekman, Harlan C.
City of Monett
352 S. Belaire
Monett, Missouri 65708
Barnes, Norman
Skinner Irrigation Company
2530 Spring Grove Avenue
Cincinnati, Ohio 45214
Bauer, W. J.
Bauer Engineering, Inc.
20 North Wacker Drive
Chicago, Illinois 60606
443
-------
Baumgardner, Robert H.
Federal Highway Administration
400 7th Street SW
Washington, D. C. 20590
Bausum, Howard T.
Army Medical,
Environmental Engr. Res. Unit
Edgewood Arsenal, Maryland 21010
Beavin, Benjamin E., Jr.
Beavin Company
104 E. 25th Street
Baltimore, Maryland 21218
Beegle, Richard G.
Baker-Wibberley § Associates, Inc.
P.O. Box 1857
Hagerstown, Maryland 21740
Beemer, Edwin F.
7 Walton Drive
New Hope, Pennsylvania 18938
Behrens, John W.
Metcalf § Eddy
60 E. 42nd Street
New York, New York 10017
Ben ton, Raymond
U.S. Forest Service
6816 Market Street
Upper Darby, Pennsylvania 19082
Berry, Charles R.
U.S. Forest Service
Carlton Street
Athens, Georgia 30601
Berry, Wade
County of Los Angeles
301 North Baldwin Avenue
Arcadia, California 91006
Berzins, Agris
Dayton k Knight Ltd.
Box 247, 1865 Marine Drive
West Vancouver, B. C., Canada
Betts, Clifford A., Jr.
Betts Engineer Company, Inc.
518 Lookout Street
Chattanooga, Tennessee 37403
Boelter, Don H.
Northern Conifers Lab.
North Central Forest Expt. Sta.
P.O. Box 872
Grand Rapids, Minnesota 55744
Boggess, William R.
Dept. of Forestry
University of Illinois
Urbana, Illinois 61801
Bohley, Paul B.
The Gorman-Rupp Company
305 Bowman Street
Mansfield, Ohio 44902
Boke, Richard L.
Reynolds Metals Company
6601 West Broad Street
Richmond, Virginia 23200
Boswell, Fred C., Dr.
University of Georgia
Georgia Station
Experiment, Georgia 30212
Botts, Lee, Mrs.
Lake Michigan Federation
53 West Jackson Boulevard
Chicago, Illinois 60604
Bourgeois, W. W.
Forestry Service
#202-130 Allard Street
Sault Ste. Marie, Ontario, Canada
Bouwer, Herman
Water Conservation Lab.
Soil and Water Res. Div.
Agricultural Research Service
U.S. Dept. of Agric.
Phoenix, Arizona 85040
444
-------
Bower, David A.
Muskingum Water Shed Conservancy Dist.
1319 3rd Street, N W
New Philadelphia, Ohio 44663
Bradford, William W.
W. Va. State Department of Health
1800 Washington Street, E.
Charleston, West Virginia 25305
Broadbent, F. E.
Dept. of Soils and Nutrition
University of California
Davis, California 95616
Brown, James L.
University of Minnesota
St. Paul, Minnesota 55100
Brown, Peter G.
Assn. for the Preservation of
Cape Cod
Box 636
Orleans, Massachusetts 02653
Bull, Robert Keith
Harza Engineer
150 S. Wacker Drive
Chicago, Illinois 60606
Burge, Wylie D.
USDA, ARS
Beltsville, Maryland 20709
Euros, Krisen
Black, Crow § Eidness, Inc.
Queens Quarter #673
Christiansted, U.S. Virgin Islands
Burrell, John
William T. Foster Associates
808 Bethlehem Pk.
Erdemheim, Philadelphia, Pa. 19118
Butler, Robert M.
Ag Engineering Dept.
Pennsylvania State Uhiversity
University Park, Pennsylvania 16802
Buzzell, Timothy
USA-CRREL
Hanover, New Hampshire 03755
Cadagan, Dan J.
Dan J. Cadagan Co.
P.O. Box 8011
Spokane, Washington 99203
Callahan, James E.
U.S. Army Engr. Div., N.E.
424 Trapelo Road
Waltham, Massachusetts 02154
Carlson, Charles
Waterways Experiment Station
OSAEC, U.S. Army Corps of
Engineers
Vicksburg, Mississippi 39180
Carson, Burke, Jr.
Multrum Corp.
Skaneateles, New York 13152
Cartier, R. E., Jr.
Environmental Health Program
Southern West Virginia Regional
Health Council
Route #2, Box 382
Bluefield, West Virginia 24701
Celenza, Paschal
One Plymouth Meeting Hall
Betz Environmental Engineers
Plymouth Meeting, Pa. 19462
Chaney, Rufus L.
USDA-ARS-Biol. Waste Mgmt. Lab.
Rm. 107, Bldg. 007, P.I. Sta.
Beltsville, Maryland 20705
Chapman, John
Valmont Industries
Valley, Nebraska 68064
Chase, F. E.
University of Guelph
Guelph, Ontario, Canada
445
-------
Cherry, Rodney N.
U.S. Geological Survey
Rm. 410, 500 Zack Street
Tampa, Florida 33602
Christensen, Lee A.
Ag. Econ. Department
Michigan State University
Room 303, 1405 S. Harrison Road
East Lansing, Michigan 48823
Christman, Richard L.
Ohio Dept. of Natural Resources
1500 Dublin Road
Division of Lands § Soil
Columbus, Ohio 43221
Clapp, C. E.,
USDA, ARS-University of Minnesota
Saint Paul, Minnesota 55101
Click, David M.
Army Corps of Engineers
Box 1159
Cincinnati, Ohio 45201
Conway, Charles R.
EPA-Region 1
Waltham Federal Center
424 Trapelo Road
Waltham, Mass. 02154
Conyers, Emery S.
Dow Chemical Company
2020 Building
Midland, Michigan 48640
Cooper, William J.
Army Medical
Environmental Engr. Res. Unit
Edgewood Arsenal
Edgewood, Maryland 21010
Crane, John S.
Harza Engineer Company
150 S. Wacker Drive
Chicago, Illinois 60606
Crites, Ronald W.
Metcalf § Eddy Inc.
1029 Corporation Way
Palo Alto, California
94303
Cruess, Robert A.
N.H. Water Pollution Control Comm.
105 Loudon Road
Concord, New Hampshire 03301
Cunningham, Hugh
Monongahela National Forest
824 15th Avenue
Marlinton, West Virginia 24954
Curran, Stephen F.
Dept. of Environmental Resources
P.O. Box 2351
Harrisburg, Pennsylvania 17105
Curtis, Willie R.
USDA, FS, Northeast Forest Expt. Sta.
204 Center Street
Berea, Kentucky 40403
Cutter, B. E.
School of Forest Resources
Pennsylvania State University
University Park, Pennsylvania 16802
Davis, Ellen
Town of Brookhaven
205 South Ocean Avenue
Patchogue, New York 11772
Davis, David E.
North Carolina State University
Box 5577
Raleigh, North Carolina 27607
Dawson, William R.
U.S. Army Corps of Engineers
502 8th Street
Huntington, West Virginia 25721
Delay, Edwin T.
U.S. Army Corps of Engineer
P.O. Box 919
Charleston, South Carolina 29402
446
-------
Dennehy, Kenneth M.
Rain Machine, Inc.
P.O. Box 291
Windsor, Connecticut
06095
De Witt, Joseph W.
U.S. Army Corps of Engineers
P.O. Box 889
Savannah, Georgia 31402
Dillon, Donald L.
U.S. Army Corps of Engineers
1114 Commerce Street
Dallas, Texas 75202
Dissmeyer, George E.
U.S. Forest Service
1720 Peachtree Street NE
Atlanta, Georgia 30309
D'itri, Frank
Michigan State University
334 Natural Res. Building
East Lansing, Michigan 48823
Dotson, Kenneth
Environmental Protection Agency
Robert A. Taft Laboratory
Cincinnati, Ohio 45226
Dovak, John L.
Pa. Dept. of Environmental Resources
996 Main Street
Meadville, Pennsylvania 16335
Drawbaugh, Daniel B.
Division of Water
Pa. Dept. of Environmental Resources
Harrisburg, Pennsylvania 17105
Edwards, I. K.
Northern Forest Research Center
5320- 122nd Street
Edmonton, Alberta, Canada
Ellingboe, James D.
Bureau of Reclamation U.S.D.A.
18th § C. Streets
Washington, D. C. 20240
Elliott, William R.
Meyer Rohlin, Inc.
1111 Highway 25N
Buffalo, Minnesota 55313
Ellis, Boyd G.
Dept. of Crop and Soil Science
Michigan State University
East Lansing, Michigan 48823
Elwood, John R.
Mass. Div. Water Pollution Control
100 Cambridge Street
Boston, Massachusetts 02202
Emerson, Richard
Mich. Water Resources Commission
Stevens T. Mason Building
Lansing, Michigan 48900
Enfield, Carl G.
Environmental Protection Agency
Washington, D.C. 20460
Evans, James 0.
U.S. Forest Service
14th § Independence Avenue
Washington, D.C. 20250
Ewell, Wesley J.
Cape May County Planning Board
Cape May Court House
Cape May, New Jersey 08210
Faucher, Francis D.
MDC Boston
20 Somerset Street
Boston, Massachusetts 02202
Fedler, Richard E.
Donohue § Associates, Inc.
4738 N. 40th Street
Sheboygan, Wisconsin 53081
Feinberg, Eli
State of Florida
Capital Building
Tallahasse, Florida
32304
447
-------
Flett, Donald R.
N. J. State Water Poll. Control
Health, Ag. Building
Trenton, New Jersey 08625
Ferullo, Alfred F.
Mass. Div. of Water Poll. Control
100 Cambridge Street
Boston, Massachusetts 02202
Fielding, H. Page
Delaware River Basin Commission
P.O. Box 360
Trenton, New Jersey 08603
Flanders, P. Howard
Vermont Dept. of Water Resources
Pavilion Office Building
Montepelier, Vermont 05602
Forester, Ted H.
Missouri Clean Water Commission
P.O. Box 154
Jefferson City, Missouri 65101
Foster, D. H.
Dept. of Civil Engineering
University of Illinois
Urbana, Illinois 61801
Foster, William T.
William T. Foster Associates
808 Bethlehem Pike
Erdemheim, Philadelphia, Pa. 19118
Fox, Fred L.
Geonics
Box 101
North Branch, New Jersey 08876
Francke, Harry C.
Union Carbide Corp.-Nuclear Division
P.O. Box y
Oak Ridge, Tennessee 37830
Freeberg, Brian M.
Stewart § Walker, Inc.
15th Street § Bemidji Avenue
Box 634
Bemidji, Minnesota 56601
Frost, Terrence P.
Water Pollution Control Commission
105 Louden Road
Concord, New Hampshire 03301
Gansell, Stuart I.
Pa. Department of
Environmental Resources
734 W. 4th Street
Williamsport, Pennsylvania 17701
Garner, Eugene F.
Metropolitan Sewer Board
350 Metro Square Bldg.
7th § Robert Street
Saint Paul, Minnesota 55101
Gentry, Claude E.
USDA, FS, Northeast Forest
Experiment Station
204 Center Street
Berea, Kentucky 40403
Gerzetich, Robert M.
Consumers Power Company
212 W. Michigan Avenue
Jackson, Michigan 49201
Giddings, Todd
Todd Giddings § Assoc.
623 W. Foster Avenue
State College, Pennsylvania 16801
Gifford, Robert D.
Walla Walla Dist. Corps of Engr.
Bldg. 604, City-County Airport
Walla Walla, Washington 99362
Ginner, Gary F.
Minn. Poll. Control Agency
717 Dela. St., S. E.
Minneapolis, Minnesota 55440
Goddard, Maurice K.
Dept. of Environmental Resources
Commonwealth of Pennsylvania
Harrisburg, Pennsylvania 17120
448
-------
Goedde, Joe
Missouri State Park Board
P.O. Box 176
Jefferson City, Missouri
Goldfine, Neil A.
New Jersey Dept. of Env. Prot.
Box 1390
Trenton, New Jersey
Gottberg, Frank
Sprinkler Irrig. Supply Co.
1316 North Campbell Road
Royal Oak, Michigan 48067
Goydan, Paul A.
Koppers
440 College Park Drive
Monroeville, Pennsylvania 15146
Graves, Diane
N. J. Sierra Club
360 Nassau Street
Princeton, New Jersey 08540
Green, Therman W.
USDA-Forest Service
1720 Peachtree Road NW, Room 716
Atlanta, Georgia 30309
Girgin, Joseph M.
Parsons, Brinckerhoff, Quade §
Douglas
111 John Street
New York, New York 10038
Griego, Alex R.
USDA-Forest Service
517 Gold Avenue SW
Albuquerque, New Mexico 87109
Guerrera, August
Suffolk County Water Authority
P.O. Box 37
Oakdale, New York 11769
Guldin, Lt. Richard W.
Wastewater Management Task Force
4H028 Forrestal Bldg.
Washington, D. C. 20314
Haines, Charles
Wright, Mclaughlin Engineers
2059 Bryant Street
Denver, Colorado 80302
Hale, Daniel
Southern W. Va. Reg. Health Council
Route 2, Box 382
Bluefield, West Virginia 24701
Hall, George
Engineer-Operations
Teledyne Triple R
111 Service Road,
Muskegon Co. Airport
Muskegon, Michigan 49441
Hall, Eric P.
Environmental Protection Agency
424 Trapelo Road
Waltham, Massachusetts 02154
Hall, Otis F.
Inst. of Natural § Environmental
Resources
University of New Hampshire
Durham, New Hampshire 03824
Hanczar, William S.
Dept. of Environmental Resources
734 W. 4th Street
Williamsport, Pennsylvania 17701
Handy, Eben N., Jr.
U.S. Army Corps of Engineers
P. 0. Box 59
Louisville, Kentucky 40201
Hansen, William
University of Missouri-Forestry
1-31 Ag. Building
Columbia, Missouri 65201
Hanson, Lowell D.
Ag. Extension Service
University of Minnesota
Saint Paul, Minnesota 55101
449
-------
Harlin, Curtis C.
Nat'l Water Quality Control Res.
Program
Environmental Protection Agency
Ada, Oklahoma 74820
Harman, Edgar H.
Garrett County Health Department
Oakland, Maryland 21550
Harman, Oscar R.
Environmental Science
Garrett Community College
McHenry, Maryland, 21520
Harris, W. F.
Environmental Sci. Div., Bldg. 3017
Oak Ridge National Laboratories
Oak Ridge, Tennessee 37830
Hart, William E.
Colorado State University
Ft. Collins, Colorado 80521
Hartmann, George Leonard
Environmental Protection Agency
Region Vlll, 1860 Lincoln Street
Denver, Colorado 80203
Haskin, Millard
Bureau of State Parks
Dept. of Environmental Resources
301 Market Street
Harrisburg, Pennsylvania 17057
Hedlund, V. A., Jr.
Valmont Industries
Valley, Nebraska 68064
Heil, James
Suffolk County Health Dept.
County Center
Riverhead, New York 11901
Helfant, M. A.
Town of Brookhaven
205 South Ocean Avenue
Patchogue, New York 11772
Helmey, Edgar L.
Soil Conservation Service
P.O. Box 985
Federal Square Station
Harrisburg, Pennsylvania 17108
Hennessey, John J.
Brookhaven National Lab
Building 134C
Upton
Long Island, New York 11973
Higbee, Roger
Pa. Dept. of Environmental Resources
300 Liberty Avenue
505 State Off. Bldg.
Pittsburgh, Pennsylvania 15222
Higgins, George C.
The Dow Chemical Company
2020 Dow Center
Midland, Michigan 48640
Hill, L. W.
U.S.D.A. Forest Service
Institute Tropical Forestry
P.O. Box AQ
Rio Piedras, Puerto Rico 00928
Hinesly, T. D.
Dept. of Agronomy
University of Illinois
Urbana, Illinois 61801
Hinkle, Richard L.
Pa. Dept. of Environmental Res.
1875 New Hope Street
Norristown, Pennsylvania 19401
Hoheneder, Joseph C.
York Co. Planning Comm.
220 S. Duke Street
York, Pennsylvania 17403
Hook, J. E.
Dept. of Agronomy
Pennsylvania State University
University Park, Pennsylvania 16802
450
-------
Hooper, Frank T.
School of Natural Resources
University of Michigan
Ann Arbor, Michigan 48104
Hortenstine, Charles C.
Soil Science Dept. (106 Newell)
University of Florida
Gainesville, Florida 32601
Hunt, Patrick G.
USA Engineer Waterways Expt. Sta.
P.O. Box 631
Vicksburg, Mississippi 39180
Hunter, Joseph V.
Dept. of Environmental Science
Rutgers University
New Brunswick, New Jersey 08903
Huntington, Lee Ann
President's Council on
Environmental Quality
722 Jackson Place
Washington, B.C. 20006
Ifft, Theodore H.
USDA Soil Conser. Service
4321 Hartwick Road
College Park, Maryland 20740
Inge, Andrew
Dept. of Environmental Resources
Bur. of State Parks, 301 Market St.
Harrisburg, Pennsylvania 17101
Irelan, Paul H.
Soil Conser. Service
Camden County
Berlin, New Jersey 08009
Jablonowski, Carl
U.S. Dept. of Agriculture
Forest Service, Allegh. Natl. Forest
P.O. Box 847
Warren, Pennsylvania 16365
Jones, Henry P.
J. Henry Jones, Inc.
3389 S. 8th E. Street
Salt Lake City, Utah 84106
Jones, Robert Lewis
University of Illinois
S. 410 Turner Hall
Urbana, Illinois 61801
Johns, J. M.
Johns Equipment Company
Route 2, Box 21
Farmville, Virginia 23901
Johnson, James F.
Waste Water Management Task Force
Department of the Army
Corps of Engineers
Washington, D.C. 20314
Jorgensen, Erik
Canadian Forestry Service
The Dept. of the Environment
4056 W. Memorial Building
344 Wellington Street
Ottawa, KIA OH3, Canada
Kam, William
U.S. Geological Survey
Trenton, New Jersey 08600
27 Canyon Road
Levittown, Pennsylvania 19057
Kappe, Stanley E.
American Academy Environmental
Engr.
Box 1278
Rockville, Maryland 20850
Kardos, Louis T.
Department of Agronomy
Pennsylvania State University
University Park, Pennsylvania 16802
451
-------
Kasabach, Haig F.
NJ Div. of Water Resources
P.O. Box 1390
Trenton, New Jersey 08625
Keller, James
Rist-Frost, Assoc.
21 Bay Street
Glenn Falls, New York 12801
Kelley, Harold A.
Jones § Henry Engrs. Ltd.
2000 W. Central Avenue
Toledo, Ohio 43606
Kelly, George T.
Metropolitan Sanitary District of
Greater Chicago
100 East Erie Street
Chicago, Illinois 60611
Kelling, Keith A.
University of Wisconsin
Soil Department
Madison, Wisconsin 53706
Kenyon, David D.
New England Division
U.S. Army Corps of Engineers
424 Trapel Road
Waltham, Massachusetts 02154
Kerfoot, William B.
Woods Hole Oceanographic Inst.
Woods Hole
Woods Hole, Massachusetts 02540
Kerslake, Richard J.
Soil Conserv. Service
1608 Oak Hill Avenue
Hagerstown, Maryland 21740
Kestner, Joseph A., Jr.
One Kestner Lane
Troy, New York 12180
Kidder, Milady
Allegheny Health Department
40th § Penn Avenue
Arsenal Health Center
Pittsburgh, Pennsylvania 15224
Kittle, Benjamin L.
Dept. of the Army
S. Atlantic Division
510 Title Building
30 Pryor Street
Atlanta, Georgia 30300
Kline, John H.
Consumers Power Co.
212 W. Michigan Avenue
Jackson, Michigan 49201
Kolega, John J.
University of Connecticut
Storrs, Connecticut 06268
Kolzow, William C.
U.S. Forest Service
Building 46
Denver Federal Center
Lakewood, Colorado 80225
Konrad, John G.
Department of Natural Resources
Box 450
Madison, Wisconsin 53702
Koo, Robert C. J.
University of Florida
P.O. Box 1088
Lake Alfred, Florida 33850
Kotyk, Eugene
Environmental Protection Service
Dept. of Environment
106-501 Univ. Court
Winnipeg, P3T2N6 Man., Canada
Kraybill, Richard
Bureau of Water Quality Management
401 Buttonwood Street
West Reading, Pennsylvania 19603
Kraft, Daniel
26 Federal Plaza
New York, New York
10007
452
-------
Krivak, Joseph A.
Planning Branch
Environmental Protection Agency
AFWP, Room 1007
Washington, D. C. 20784
Kronis, Henry
Ministry of the Environment
135 St. Clair Avenue, W
Toronto, Ontario, Canada
Kudrna, Frank L.
Metropolitan Sanitary District of
Greater Chicago
100 East Evie Street
Chicago, Illinois 60611
Kutzman, James S.
Environmental Protection Agency
Suite 204
1421 Peachtree Street, N.E.
Atlanta, Georgia 30309
Larson, Carl
Environmental Resources Association
P.O. Box 2259
Monterey, California 93940
Layman, John
The Stratton Corporation
Stratton Mountain
Stratton, Mountain, Vermont 05340
Leischen, Nicholas
State of Florida
3399 Ponce De Leon
Coral Gables, Florida
Lejcher, Terrence R.
Shawnee National Forest
U.S. Forest Service
Harrisburg, Illinois 62946
Lewis, Donald
Geography Department
Uhiversity of Toledo
Toledo, Ohio 43606
Lindorff, David
Bureau of Water Quality Management
1875 New Hope Street
Norristown, Pennsylvania 19401
Little, Silas
Northeastern Forest Expt. Sta.
P.O. Box 115
Pennington, New Jersey 08534
Livingston, David
U.S. Silver § Mining Co.
1701 Lake Avenue
Glenview, Illinois 60025
Livingston, Robert
U.S. Silver § Mining Company
1701 Lake Avenue
Glenview, Illinois 60025
Lorenzen, Douglas
Department of Environmental
Resources
Harrisburg, Pennsylvania 17109
Losche, Craig
U.S. Forest Service
c/o Forestry Sciences Lab.
Southern Illinois University
Carbondale, Illinois 62901
Ludington, David
Cornell University
Riley Robb Hall
Ithaca, New York 14850
Lunin, Jesse
U.S. Department of Agriculture
Ag. Research Service
Room 127 Admn. Bldg.
Beltsville, Maryland 20705
Lyon, Walter A.
Bureau of Water Quality Management
Dept. of Environmental Resources
Harrisburg, Pennsylvania 17109
453
-------
Mace, Arnett
College of Forestry
University of Minnesota
St. Paul, Minnesota 55101
MacLauchlin, Robert
U.S. Army Corps of Engineers
536 South Clark Street
Chicago, Illinois 60605
Magnuson, Paula
Association for the Preservation
of Cape Cod
Box 636
Orleans, Massachusetts 02653
Maneval, David
Appalachian Region Commission
1666 Connecticut Avenue, N.W.
Washington, D. C. 20235
Marino, James
Pennsylvania Department of
Environmental Resources
996 Main Street
Meadville, Pennsylvania 16335
Markstrom, Donald
U.S. Forest Service
240 West Prospect Street
Fort Collins, Colorado 80521
Marsh, John
Engineering Enterprises
123 E. Tonhawa
P.O. Box E
Norman, Oklahoma 73069
McKernan, J. M.
York University
4700 Keele Street
Downs view 463, Ontario, Canada
Mclaughlin, William
U.S. Forest Service
P.O. Box 3623
Portland, Oregon 97208
McMaster, Ronald
Milford Water Authority
Milford, Pennsylvania 18337
McNeill, Peggy
League of Women Voters
Bloomfield Avenue
Montclair, New Jersey 07042
McNenny, Darrell
USDA Forest Service
Missoula, Montana 59801
McWilliam, Peter
Christchurch Drainage Board
P.O. Box 13006 Armagh
Christchurch, New Zealand
Merritt, James
Department of the Army, So. Atlantic
Div., Corps of Engineers
510 Title Building
30 Pryor Street, S.W.
Atlanta, Georgia, 30303
Metzger, Barbara
Environmental Protection Agency
26 Federal Plaza
New York City, New York 10007
Michael, Alan
Pope, Evans and Robbins
11 E. 36th Street
New York, New York 11803
Miller, Robert H.
Dept. of Agronomy
Ohio State University
Columbus, Ohio 43210
Miller, Harold
Beavin Company
104 E. 25th Street
Baltimore, Maryland
21218
Minning, Robert
W. G. Keck § Associates, Inc.
4903 Dawn Avenue
East Lansing, Michigan
48823
454
-------
Mizell, Roger
U.S. Forest Service
1720 Peachtree Street, N.W.
Atlanta, Georgia 30309
Montgomery, Wayne
Harland Bartholomew § Associates
165 North Meramec
Clayton, Missouri 63105
Moore, Harold
University of Delaware
College of Marine Studies
Newark, Delaware 19711
Moorshead, Frank
Roy F. Weston, Inc.
Lewis Lane
West Chester, Pennsylvania 19380
Morgan, Wayne
Kellogg's Supply Company
238 13 Cholame Drive
Diamond Bar, California 91765
Moser, John
Pennsylvania Department of
Environmental Resources
300 Liberty Avenue
Pittsburgh, Pennsylvania 15222
Mudrak, Vincent
Pennsylvania Fish Commission
Box 200-C
Bellefonte, Pennsylvania 16823
Myers, Earl A.
Dept. of Agricultural Engineering
Pennsylvania State University
University Park, Pennsylvania 16802
Near, C. R.
Hastings Irrig. Pipe Co.
P.O. Box 607
Hastings, Nebraska 68901
Neil, Forrest
The Metropolitan District of
Greater Chicago
100 East Erie
Chicago, Illinois 60611
Nesbitt, John B.
Dept. of Civil Engineering
Pennsylvania State University
University Park, Pennsylvania 16802
Newmann, Thomas
Environmental Engineer Service
State Department of Health
Lucas Building
Des Moines, Iowa 50320
Newell, S. David
McDowell Manufacturing Company
P.O. Box 665
DuBois, Pennsylvania 15801
Norris, Logan
U.S. Forest Service
Forestry Sciences Laboratory
3200 Jefferson Way
Corvallis, Oregon 97330
Norum, Edward
McDowell Manufacturing Company
P.O. Box 665
DuBois, Pennsylvania 15801
Nussbaumer, William
Tennessee Valley Authority
TVA Forestry Building
Norris, Tennessee 37918
O'Dell, John
U.S. Soil Conservation Service
R. 200 Fed. Courts Building
316 N. Robert Street
Saint Paul, Minnesota 55101
O'Leary, Phillip
Department of Natural Resources
Box 450
Madison, Wisconsin 53702
Oleson, Harry, Jr.
U.S. Geological Survey
500 Zack Street
Tampa, Florida 33602
455
-------
Oleson, S. Melodic
SW Florida Water Management
District
P.O. Box 457
Brooksville, Florida 33512
Olson, Olaf C.
Environmental Management Section
Div. of Watershed Management
U.S. Forest Service
Washington, B.C. 20250
Otke, Ken
Missouri State Park Board
P.O. Box 176
Jefferson City, Missouri 65101
Overman, Allen
Agriculture Engineering
University of Florida
Gainesville, Florida 32601
Padgett, William
U.S. Forest Service
6816 Market Street
Upper Darby, Pennsylvania 19082
Parizek, Richard R.
Dept. of Geology
Pennsylvania State University
University Park, Pennsylvania 16802
Parmelee, Donald
C. W. Thornthwaite Associates
Route 1, Centerton
Elmer, New Jersey 08318
Parrett, Neil
U.S. Army Corps of Engineers
HQDA (DAEN-CWE-S)
Washington, D. C. 20314
Parrott, Lawrence
McDowell Manufacturing Company
P.O. Box 665
DuBois, Pennsylvania 15801
Paschke, Robert
Rieke-Carrol-Muller Associates
Box 130
Hopkins, Minnesota 55343
Peffer, Jeffrey
Bureau of Water Quality Management
29 Chestnut Street
Lewistown, Pennsylvania 17044
Pepper, Leonard
Waterways Express Station
Box 631
Vicksburg, Minnesota 39180
Peterson, James R.
Metropolitan Sanitary District
of Greater Chicago
Research and Development Lab.
5901 W. Pershing Road
Cicero, Illinois 60650
Peterson, Mark
Extension of Agriculture
University of Missouri
Columbia, Missouri 65201
Pierce, James
Van Note-Harvey Associates
Box 623
Princeton, New Jersey 08540
Pierce, Donald M.
Division of Wastewater
Bur. of Environmental Health
Dept. of Public Health
Lansing, Michigan 48914
Pierce, Robert
Water Resources Section
Lake Central Region
Bureau of Outdoor Recreation
Ann Arbor, Michigan 48104
Poloncsik, Stephen
Environmental Protection Agency
1 North Wacker Drive
Chicago, Illinois 60606
456
-------
Poole, Allan
City of Naperville
305 Jackson Street
Naperville, Illinois 60540
Pound, Charles
Metcalf § Eddy, Inc.
1029 Corporation Way
Palo Alto, California
94303
Pounds, William
Pennsylvania Department of
Environmental Resources
Box 2351
Harrisburg, Pennsylvania 17103
Pulsonetti, P. C.
Town of Brockhaven
205 South Ocean Avenue
Patchogue, New York 11772
Ragone, Stephen
U.S. Geological Survey
1505 Kellum Place
Mineola, New York 11501
Rasmussen, Dale
Hastings Irrig. Pipe Company
P.O. Box #607
Hastings, Nebraska 68901
Ray, Griffith
U.S. Corps of Engineers
Ohio River Division
P.O. Box 1159
Cincinnati, Ohio 45201
Reed, Charles
Agricultural Engineering
Rutgers State University
New Brunswick, New Jersey
08903
Reid, Denyse
Princeton Conservation Commission
Township Hall
Princeton, New Jersey 08540
Reid, Michael
Ministry of the Environment
Plant Operations Branch
135 St. Clair Avenue
Toronto, Ontario, Canada
Reid, Robert
Town of Brookhaven
205 S. Ocean Avenue
Patchogue, New York 11772
Reid, William
Department of the Army
Corps of Engineers
Mobile District
P.O. Box 2288
Mobile, Alabama 36601
Rhindress, Richard C.
Ground Water Quality Management Unit
Division of Water Quality
Dept. of Environmental Resources
Harrisburg, Pennsylvania 17701
Rhodes, John
John C. Reutter Associates
9th § Cooper Streets
Camden, New Jersey 08101
Riddle, William
Riddle Engineering
3847 State Line
Kansas City, Missouri
64111
Risley, Clifford
Environmental Protection Agency
1 North Wacker Drive
Chicago, Illinois 60606
Ritter, William
College of Ag. Science
University of Delaware
Newark, Delaware 19711
Rodrigue, Raymond
Co. Sanitation Dists. of Los Angeles
24501 S. Figueroa Street
Harbor City, California 90710
457
-------
Rodriguez, Jose
Environmental Quality Board
P.O. Box 11488
Santurce, Puerto Rico 00910
Rohland, F. J.
Bauer Engineering, Inc.
20 North Wacker Drive
Chicago, Illinois 60606
Rome, Samuel
Pres's. Water Pollution Control
67 E. Madison (L. of W. Voters)
Chicago, Illinois 60603
Ruddo, Mike
W.S.S.C
4017 Hamilton Street
Hyattsville, Maryland 20781
s
Russell, James
McDowell Manufacture Company
P.O. Box 665
DuBois, Pennsylvania 15801
Ryan, James
Department of Soil Science
University of Wisconsin
Madison, Wisconsin 53700
Sabey, B. R.
Colorado State University
Fort Collins, Colorado 80521
Sargent, Benson
Environmental Engineering
Division of Protection
Pavilion Building
Moneplier, Vermont 05602
Sartz, Richard
North Central Forest Experiment
Station, Forest Watershed Lab.
P.O. Box 872
LaCrosse, Wisconsin 54601
Schicht, Richard
Illinois State Water Survey
P.O. Box 232
Urbana, Illinois 61801
Schmidt, Joyce
State League of Women Voters
Environmental Quality Commission
Bloomfield Avenue
Montclair, New Jersey 07042
Schorr, Paul
N.J. Department of Environmental
Protection
P.O. Box 1390
Trenton, New Jersey 08600
Schulze, K. L.
Department of Civil Engineers
Michigan State University
East Lansing, Michigan 48823
Schwert, Donald
Department of Forest Zoology
College of Forestry
University of Syracuse
Syracuse, New York 13210
Scilley, F. Maynard
USDA Soil Conservation Service
Room 200, Federal Center Bldg.
St. Paul, Minnesota 55101
Scott, Jon
Department of Atmospheric Science
State University at Albany
1400 Washington
Albany, New York 12222
Seabrook, Belford L.
Div. of Municipal Waste Water Programs
Office of Water Programs
Environmental Protection Agency
Washington, D. C. 20460
Shafer, E. L., Jr.
Pinchot Institute
Northeastern Forest Experiment Station
6816 Market Street
Upper Darby, Pennsylvania 19082
Shaffer, James
Department of Natural Resources
65 S. Front Street ,
Columbus, Ohio 43215
458
-------
Shane, Richard
Argonne National Laboratory
9700 S. Gass Avenue, Bldg. 12,
Center for Environmental Studies
Argonne, Illinois 60439
Shanklin, Don
USDA Soil Conservation Service
400 Midtown Plaza, 700 E. Water St.
Syracuse, New York 13031
Slack, Larry
U.S. Geological Survey
Rm. 414, 1309 Thomasville Rd.
Tallahassee, Florida 32303
Small, Maxwell
Brookhaven National Laboratory
Upton, New York 11973
Smith, Clyde
U.S. Army Corps of Engineers
P.O. Box 4970
Jacksonville, Florida 32201
Smith, Ivan
Mid-West Research Institute
425 Volker Blvd.
Prairie Village, Missouri 66208
Smith, James
Town of Amherst
Town Hall
Amherst, Massachusetts
01002
Smith, Milburn
U.S. Army Corps of Engineers
P.O. Box 17300
Fort Worth, Texas 76102
Smith, Thomas
City of Tallahassee
City Hall
Tallahassee, Florida 32303
Solomon, R. Charles
U.S. Aimy Corps of Engineers
P.O. Box 1715
Baltimore, Maryland 21203
Sopper, William E.
School of Forest Resources
Pennsylvania State University
University Park, Pennsylvania 16802
Sowash, James
Pennsylvania State University
401 Old Main
University Park, Pennsylvania 16802
Speakman, James
Buffalo N.Y. Corps of Engineers
1776 Niagra Street
Buffalo, New York 14207
Stanley, Ronald
U.S. Forest Service
P.O. Box 1050
Tallahassee, Florida 32302
Stanlick, Harold
U.S. Forest Service
633 W. Wisconsin Avenue
Milwaukee, Wisconsin 53074
Stansbury, Jeffrey
5902 32nd Street, N.W.
Washington, B.C. 20015
Stephenson, Marvin
The Rockefeller Foundation
111 W. 50th Street
New York, New York 10020
Stetson, John
U.S. Army Corps of Engineers
2850 SE 82nd
Portland, Oregon 97266
Stevenson, Charles
Tech. Development
Curtice - Burns, Inc.
P.O. Box 670
Rochester, New York 14602
Steward, Kerry
USDA ARS PSR
3205 S.W. 70th Avenue
Fort Lauderdale, Florida
33314
459
-------
Stewart, Gordon
University of Massachusetts
Amherst, Massachusetts 01002
Strand, Bruce
R. R. 1
Ava, Illinois
Strauser, Brad
U.S. Army Engineer District
210 N. 12th Street
St. Louis, Missouri 63101
Stucky, Glenn E.
Soil Conservation Service
7600 West Chester Pike
Upper Darby, Pennsylvania 19082
Sturm, William
430 W. Seymore Avenue
Cincinnati, Ohio 45216
Summers, Phillip
Forest Service
U. S. Department of Agriculture
Washington, D. C. 20250
Sutherland, Jeffrey
Williams § Works
250 Michigan, N.E.
Grand Rapids, Michigan 49503
Swafford, Benny
DAEN-CWE-Y
Forrestal Building
Washington, D. C. 20314
Sydnor, Bernard
Michaux Forest Garden Estates, Ltd.
Box 181
Fairfield, Pennsylvania 17320
Taber, James
Pennsylvania Department of
Environmental Protection
Harrisburg, Pennsylvania 17101
Tabor, Lance
Southern W. Va. Reg. Health Council
Route 2, Box 382
Bluefield, West Virginia 24701
Tanner, Howard
Michigan State University
109 Natural Resources Building
East Lansing, Michigan 48840
Tarquin, Anthony
University of Texas - El Paso
Department of Civil Engineering
El Paso, Texas 79968
Tennant, Harold
R. M. Wade Company
Irrigation Division
1919 N. W. Therman Street
Portland, Oregon 97200
Thomas, Richard E.
Nat'l. Water Quality Control Program
Robert S. Kerr Water Res. Center
Environment Protection Agency
Ada, Oklahoma 74820
Thompson, D. R.
Pennsylvania Department of
Environmental Resources
Rm. 513, S. Office Building
Harrisburg, Pennsylvania 17105
Thompson, Jack
U.S. Army Corps of Engineers
Room 5F-079 DAEN-CWE-M
Forrestal Building
Washington, D. C. 20314
Tofflemire, T. James
N.Y.S. Department of Environmental
Conservation
50 Wolf Road
Albany, New York 12200
Turner, John
University of Missouri
1-31 Agriculture Building
Columbia, Missouri -65201
460
-------
Urie, Dean H.
North Central Forest Experiment Sta.
U.S. Forest Service
Cadillac, Michigan 49601
Vaccaro, Ralph
Woods Hole Oceanographic Inst.
Woods Hole, Massachusetts 02574
Van Aacken, Karen
McCombs-Khutson Assoc., Inc.
12805 Olson Memorial Highway
Minneapolis, Minnesota 55441
Vayansky, Thomas
Pennsylvania Department of
Environmental Resources
300 Liberty Avenue
Pittsburgh, Pennsylvania 15222
Vermillion, Lois
Interstate Commission on
Potomac River Basin
1025 Vermont Avenue, N.W.
Suite 407
Washington, D. C. 20005
Vhora, Mansukhlal
Yule Jordan § Assoc.
Box 337
Camp Hill, Pennsylvania 17011
Vodehnal, Dale
Environmental Protection Agency
Region Vlll, Suite 900,
1660 Lincoln Street
Denver, Colorado 80203
Voykin, Dale
Bureau of Water Quality Mgmt.
734 W. Fourth Street
Williamsport, Pennsylvania 16701
Wakat, Cynthia
U.S. Army Corps of Engineers,
Regional Chicago District
2195 Dearborn
Chicago, Illinois 60604
Walker, Ian
Stony-Brook-Millstone Watersheds
Associates
P.O. Box 171
Pennington, New Jersey 08534
Walker, John
USDA, ARS
Plant Industry Station
Beltsville, Maryland 20810
Waller, James
Wilmington District, U.S. Army
Corps of Engineers
Wilmington, North Carolina 28401
Ward, Richard
U.S. Department of Agriculture
P.O. Box 847
Warren, Pennsylvania 16365
Warner, John
USDA Soil Conservation Service
Room 40, Midtown Plaza
700 E. Water Street
Syracuse, New York 13210
Warther, Fred
Lake Contractors Inc.
7100 Lory Lane, Box 24
Lanham, Maryland 20801
Watt, J. Thomas
Van Reuth and Weidner, Inc.
5509 York Road
Baltimore, Maryland 21212
Webb, Jack
Environ. Control Corporation
153 E. Erie, Suite 404
Painesville, Ohio 44077
Weiss, Martin
Deer Island Th. Ph.
Metropolitan District Commission
P.O. Box 100
Winthrop, Maryland 02152
461
-------
Welch, Allan
Bureau of Water Quality
996 S. Main Street
Meadville, Pennsylvania 16335
Wentzel, Eugene
Pennsylvania Department of
Environmental Resources
401 Buttonwood Street
Reading, Pennsylvania 19602
Westlund, Carlyle
Groundwater Section
Bureau of Water Quality Mgmt.
P.O. Box 2351
Harrisburg, Pennsylvania 17120
Whaling, Patrick J.
Duke University
Beaufort, North Carolina 28516
Whitaker, James
Agricultural Engineering
University of Connecticut
Box U 15
Storrs, Connecticut 06268
White, Richard
Department of Agricultural
Engineering, 2073 Neil Avenue
Ohio State University
Columbus, Ohio 43210
Wikre, Dale
Minnesota Pollution Control Agency
717 Delaware, S.E.
Minneapolis, Minnesota 55440
Wiles, Carlton
Solid Waste Research Division
NERC-CIN EPA, 5555 Ridge Avenue
Cincinnati, Ohio 45242
Williams, T. C.
Williams and Works
250 Michigan Street, N.E.
Grand Rapids, Michigan 49503
Williams, Calrke
Marine Resources Council
Hauppague, New York
Wilson, Charles
Louisiana Tech. University
Ruston, Louisiana 71270
Wilson, George
Geraghty § Miller, Inc.
44 Sintsink Drive East
Port Washington, New York 11050
Winnike, Richard
Corps of Engineers (MRD)
215 N. 17th Street
Room 7020
Omaha, Nebraska 68101
Wong, Walter
County of Monterey
Public Health Department
1270 Natividad Road
Salinas, California 93901
Wood, Gene W.
School of Forest Resources
Pennsylvania State University
University Park, Pennsylvania 16802
Woodcock, Gene
Water Pollution Control
Box 337
Sumner, Iowa 50674
Inc.
Wooding, Henry N.
203 Ag. Engr. Building
Pennsylvania State University
University Park, Pennsylvania 16802
Wright, Darwin
Office of Research and Monitoring
Environmental Protection Agency
Washington, D. C. 20460
Yesh, John
Department of Environmental Resources
383 Wyoming Avenue
Kingston, Pennsylvania
462
-------
Youngner, V. B.
Department of Plant Sciences
University of California
Riverside, California 92502
Zagar, Michael
Minn. Pollution Control Agency
717 Delaware Street, S.E.
Minneapolis, Minnesota 55440
Zagloul, Omar
Lindsay Manufacturing Company
Lindsay, Nebraska 68644
Zampogna, Ralph
Bureau of Water Quality Management
1875 New Hope Street
Norristown, Pennsylvania 19401
Zemaitis, William
Aerobic Systems, Inc.
4 West 58th Street
New York, New York 10019
Zimmerman, R.
Perma Engine
2010 Cogay Avenue
Winnipeg, Manitoba, Canada
Zoda, Arthur
N.J.D.E.P.
John Fitch Plaza
Trenton, New Jersey 08618
Zwalinski, John
Department of Environ. Resources
1875 New Hope Street
Norristown, Pennsylvania 19401
Zweig, Richard
U.S. Forest Service
Room 708, 1720 Peachtree Road
Atlanta, Georgia 30309
463
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
/. Report No.
2.
• -
3. Accession Ho.
w
4. Title "Conference on Recycling Treated Municipal
Wastewater Through Forest and Cropland"
7. Aathor(s)
William E. Sopper and Louis T. Kardos (ed.)
5. Organization
The Pennsylvania State University
, University Park, Pennsylvania 16802
Institute for Research on Land and Water Resources
5. Report Date
6.
8. Performing Organization
Report No.
10. Project No.
R-800678
11. Contract/Grant No.
3. Type i / Repo, t and
i Period Covered
12. Spossoriar Organisation
15. Saii;>lementAry Nnies
EPA Project Report No. EPA-660/2-74-003, March 1974.
16. Abstract
Intense interest in preserving the quality of our environment has reactivated interest
in the management of wastewaters by applying them to the land. Use of land appli-
cation approaches for wastewater management must be updated to conform to our new
concepts of conserving and protecting the quality of our land and water resources.
Design and operation of land-based wastewater management systems is dependent on
site selection, the degree of water renovation desired, and the planned use of the
site as well as the basic physical, chemical, and biochemical processes which
influence system performance. The 32 individual papers included in this report are
presented in sections which cover municipal wastewater characteristics, the function
of the soil in the treatment process, vegetation responses, system design and cost,
examples of operating systems, and the status of guidelines for land disposal of
wastewater.
17a. Descriptors
*Pollution abatement, *Wastewater treatment, *Tertiary treatment, *Conferences,
*Crop response, *Groundwater recharge, *Soil~water-plant relationships, *Municipal
wastes, Cycling nutrients, Agronomic crops, Forests, Sprinkler irrigation,
Environmental effects, Land use, Design data, Pathogenic bacteria, Costs.
17b. Identifiers
*Wastewater reuse, *Wastewater irrigation.
lie. COWRR Field & Group Q3C, 04B, 05D
18. Availability
19. Security Class.
%; '(Report
$0. Sec irity Ctess.
(Page) ""~.,
21, No. of
Pages
fi. jf»«v*
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 2O24O
Abstractor
Institution
ft U, S. GOVERNMENT PRINTING OFFICE : 1974 720-063/301
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