EPA-902/9-73-001
PROCEEDINGS OF CONFERENCE ON LAND
DISPOSAL OF MUNICIPAL EFFLUENTS AND
SLUDGES
1973
DISTRIBUTED BY:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
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Proceedings of
Conference on
LAND DISPOSAL OF MUNICIPAL EFFLUENTS AND SLUDGES
Sponsors
U. S. Environmental Protection Agency, Region II
and
College of Agriculture and Environmental Science, Rutgers University
PRICES SUBJECT TO CH&MGE
l*iiviro"i;-. , r,", -J. I'i-rvU •;,,'. .1 ;>'-,>r,(*y
B^rlcn V, I.
Rutgers - The State University of New Jersey
March 12 and 13, 1973
Reproduced by
NATIONAL TECHNICAL
INFORMATION SERVICE
U S Department of Commerce
Springfield VA 22151
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LAND DISPOSAL OF MUNICIPAL EFFLUENTS AND SLUDGES
Symposium Chairman
R. W. Mason
U. S. Environmental Protection Agency, Region II
Welcoming Address
C. E. Hess
Dean of the College of Agriculture and Environmental Science
Rutgers University
Table of Contents
Page
PART I - Sludge Disposal on the Land
Session 1: G. K. Dotson, Chairman
Sludge Characteristics of Municipal Solids 3
A. J. Kaplovsky and E. Genetelli
Disposal and Reuse of Sludge and Sewage: What 19
are the Options
R. B. Dean
Soils as Sludge Assimilators 31
J. 0. Evans
Modes of Transporting and Applying Sludge 53
W. J. Bauer
Session 2: R. B. Dean, Chairman f
Some Constraints of Spreading Sewage Sludge on Cropland 67
G. K. Dotson
Methods of Liquid Fertilizer Application 81
B. T. Lynam and R. 0. Carlson
ii
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Table of Contents
(Continued)
Page
Equipment for Incorporating Sewage Sludge and 91
Animal Manures into the Soil
C. H. Reed
Sludge Disposal Studies at Beltsville 101
J. M. Walker
Merchandizing Heat-Dried Sludge 117
C. G. Wilson
Ocean County Sewerage Authority Wastewater Solids 125
Utilization on Land Demonstration Project
M. Gritzuk
PART II - Land Treatment of Municipal Effluents
Session 3: W. R. Duffer, Chairman
EPA Viewpoint on Land Application of Liquid Effluents
J. R. Trax
Land Treatment and Environmental Alternatives
B. Reid
New York State's View of Land Disposal 151
F. 0. Bogedain
Session 4: A. J. Kaplovsky, Chairman
Municipal Effluent Characteristics
J. V. Hunter
Fate of Materials Applied 181
R. E. Thomas
Protection of Public Health 201
C. A. Sorber
iii
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Table of Contents
(Continued)
Session 5: R. E. Thomas, Chairman
Experiences with Land Spreading of Municipal Effluents 211
R. E. Thomas and C. C. Harlin
Presented by W. R. Duffer
Nationwide Experience in Land Treatment 227
C. E. Pound and R. W. Crites
A Survey of Land Application of Wastewater Facilities 245
R. H. Sullivan
This Proceedings was Prepared and Published
by
The Office of Research and Development
U. S. Environmental Protection Agency, Region II
Gerald M. Hansler, P.E., Regional Administrator
iv
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NOTICE
THIS DOCUMENT HAS BEEN REPRODUCED FROM
THE BEST COPY FURNISHED US BY THE SPONSORING
AGENCY. ALTHOUGH IT IS RECOGNIZED THAT CER-
TAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RE-
LEASED IN THE INTEREST OF MAKING AVAILABLE
AS MUCH INFORMATION AS POSSIBLE.
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Greetings to Conference
Land Disposal of Municipal Effluents and Sludges
Dean Charles E. Hess
March 12, 1973
It is a privilege to cooperate with the U. S. Environmental
Protection Agency, Region II, in the sponsorship of this conference. The
subject of Land Disposal of Municipal Effluents and Sludges has been of
intense interest and study by our College for a number of years. Initially,
we were concerned with disposal of animal manure. Incorporating it in
the soil was one approach. Throughout the research we have tried to look
at the problem from an interdisciplinary standpoint - Dr. Kaplovsky's
Department of Environmental Sciences has been monitoring the quality
and the fate of sewage sludge and microbial aerosols produced in the
incorporation of sewage sludge in the soil. Scientists in the Soils and
Crops Department have been studying the interaction between soils and
the components of the sludge - nutritive components and potential heavy
metal problems. They are also concerned with the use of crops to
remove nitrogen that is released during the decomposition of sewage
sludge. The Biological and Agricultural Engineering Department has
developed a delivery system to incorporate solid wastes into the soil.
We are fortunate to have General William Whipple of the Water Resources
Bureau on our campus to provide support and concern for water quality in
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areas used for sludge disposal. The results of the initial studies indicate
the concept is feasible but not without problems such as potential ground
water contamination and heavy metal contamination of soil even from
domestic sludge.
Although there are problems, the potential is great. We
see the use of land as a disposal site and assimilator of municipal efflu-
ents and sludges as a way to help maintain open space in New Jersey and
to bring together in a muturally beneficial way an urban problem with
agricultural production. If the problems can be overcome and if we do
not end up trading one pollution problem off for another, we will have
gone a long way to solving a critical problem for municipalities in such
a way that we enhance the productivity of our environment.
You have a distinguished group of speakers and they will
explore all the aspects of the problem. I am sure when you leave this
afternoon you will have a much greater appreciation for the complexity
and the potential of Land Disposal of Municipal Effluents and Sludges.
If there is anything we at the College can do to make your
stay more comfortable and rewarding, please let us know - we are here
to serve you.
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Sludge Characteristics of Municipal Solids
by
A. J. Kaplovsky*and E. Genetelli**
Everyone knows the practice of land disposal of human, animal
and vegetable wastes has been in existence for many centuries. The
practices can vary from the most primitive to the most complex. The
degree of sophistication is dependent upon the local, social and
economic conditions and the sludge characteristics.
Some of you may have seen and experienced as I have the land
disposal procedures of the far East where waste application produce
a stalk of celery 6 inches in diameter and over 2 feet long. How
is it possible to maintain soil fertility year after year with
natural fertilizers when they contain less than 1/3 of the important
constituents present in the "so-called" complete fertilizers of
today?
These farmers knew very little or cared less about how much
N, HjPO^, or potash were in their wastes. Raw experience of trial
and error told them that laddling annually a thick slurry of foul
smelling natural wastes around their plantings produced a luscious
looking green crop. They knew very little or care'd less about
the scientific explanations. They just knew it worked' They
didn't choose to use human waste because its organic form of
nitrogen is of longer duration and that the plant fed more con-
tinuously. They were oblivious to the countless billions of
little nitrogen fixation factories found in sludge which take
nitrogen from the air and convert it to the form of nitrogenous
compounds easily assimilated by plant life. The importance of
organic matter and its moisture retention characteristics was
wasted on these farmers. Nor did they care how such sludges keep
dissolved nutrients in contact with roots for a much longer time
than would otherwise be possible; or how sludges may help heavy
clay soils become more porous and workable. It is not known
whether these farmers were forced to use these partially decomposed
slurries because they had to fertilize annually. Perhaps they
could not wait the two or three years for stabilized odorless
organic residue to reach equilibrium under natural conditions. It
is also not known whether they tried both types of fertilizers and
*Chairman and **Associate Research Professor Respectively
Department of Environmental Sciences
CAES, Rutgers University. Presented March 12, 1973 at
"Land Disposal of Municipal Effluents and Sludges" conference,
Rutgers University
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found the foul smelling slurry was more effective than the stabilized
solids. It is rather certain however these farmers were not aware
that by permitting their wastes to "sour" the early acidification
and liquefaction stages of sludge digestion were set in motion
wherein growth promoting substances were being produced from indole
and skatole in the form of indole acetic, indole propionic and indole
butyric acids. The odorous butyric acids and mercaptans produced
during initial stages of degradation did not deter them from using
such material. I recall my experience in the late 30's as a lab-
oratory assistant while looking for the presence of growth promoting
by-products indole and skatole in solids wastes. The thing I most
vividly recall is that the most repulsive smelling flesh scrappings
from animal hides had the highest content of indole and skatole.
This practice of "night soil" application represents the extreme
end of the spectrum from which we wish to escape. The parade of
oxen drawn "honey carts" carrying the foul smelling slurries is
something most of us who have seen this want to forget but can not
forget. More importantly, we must recognize the tremendous health
problem associated with such ancient practices. While in Korea,
my roommate, who was a pathologist, examined hundreds of stool
specimens and found 85% of the Koreans had one to three intestinal
diseases. Obviously the chance of disease negates any advantages
of such procedures. We must direct our attention to the problem
of handling stabilized solids.
The rate of solids accumulation has reached such proportion
that we can no longer depend upon the trial and error approach of
the past to solve a problem which now demands a very high degree
of control and perhaps reuse. As many of your are aware, restric-
tions on ocean dumping have increased. Further, recent stack
analyses utilizing current combustion practices of plain domestic
solids makes it questionable whether this direction will be accept-
able for very long. The traditional trial and error approach which
evolved from art to invention toward science must now be reversed
wherein the science must precede the invention and art.
Thirty-five years ago, Dr. Wilhelm Rudolfs, the first Chairman
of our Department of Environmental Sciences and in my opinion, a
sage in the art of waste treatment, made the profound statement
that waste treatment is only as effective as its solids handling
capability. It was not until recent years that most professionals
in the field were fully confronted with or forced to fully examine
the magnitude of this phase of the problem. How often have you
seen enforcement guidelines that have specific constituent limi-
tations for the liquid effluent discharge and in another section
merely state that the accumulated solids be disposed of "in an
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acceptable manner," without further stipulation? Perhaps the
problem was so complex that they were loathe to attack it. Here-
tofore, the handling of the dilute solids systems has always
been one of initially dewatering or further concentrating the
suspended and dissolved solids phase. The ultimate disposal of
suoh concentrated solids were given comparatively little attention
or control.
If we are to avoid repeating our past mistakes we must invoke
certain basic rules. (1) The conditions under which land disposal
is to operate must control the characteristics and composition of
municipal waste solids to be applied not vice versa. Presently,
solids handling at the source produces sludge pursuant to the state
of the art and then a suitable means of ultimate disposal is sought,
Unfortunately, more often than not, the two are not congruent
thereby forcing less than completely satisfactory solution imple-
mentations simply because sludge is a daily occurrence and some-
thing must be done in haste to overcome such accumulations. (2)
In a densely populated and an industrial society, the dilution
concept - out of site out of mind - has rapidly become infeasible
or unacceptable. In fact, new legislation and developments have
made it suspect to continue discharge of solids to the ocean and/or
combustion of such solids. In effect, these turn of events have
made it mandatory to reconsider land disposal as a major outlet.
(3) We must be more searching and knowledgeable before we give
our blessing to massive land disposal as a relatively simple tech-
nological solution. It has also become a difficult social and
economic problem.
Solids in its various forms reaching municipal systems have
as their origin, the water supply, bathroom, kitchen, commercial
establishments, street wash, storm water, infiltration and indus-
trial wastes. The physical state of these solids, whether they be
suspended, colloidal or dissolved are largely influenced by their
mode of transport, freshness or age of waste waters, temperature,
pH or presence of industrial wastes, constituent concentration and
composition will vary hour to hour, day to day, season to season,
year to year depending upon the habits of the people; waste col-
lection practices; plant design and the type of contributions to
the system. Solids will not only appear as suspended, dissolved
or colloidal material but will occur as grit and scum. At best
municipal solids may show general similarities on occasion. How-
ever to seek reproducible constituent content and concentration
would be like "looking for a needle in a haystack".
Certainly, we can surmise that certain elements will be
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present which had as their origin our food, our water supply,
street wash or grit, or our industries. Further, and to a large
extent we can assume these elements originated from natural
sources and by means of land disposal we would be returning
these elements from whence they came. However, land disposal
sites for developed communities would rarely be located where the
food was grown or the chemicals withdrawn. Any concentration of
people and/or development will result in a concentration of these
elements thereby compounding the waste handling problem.
A basic objective is to prepare this conglomerate mass of
solids for land disposal. Such preparation must be related to the
land disposal management systems under consideration. Ideally,
the sludge should be well digested, innocuous, readily dewaterable
and "essentially" domestic. Unfortunately domestic type waste is
a rarity. We must assume all such wastes are typically municipal
in nature and containing heavy metals. Further, the constituent
levels in the sludges now being produced and the solids handling
facilities in situ will dictate or limit land disposal practices.
Presently we are being forced into adopting land disposal manage-
ment procedures to handle the type of waste we have on hand rather
than control the waste composition at the source so that the best
possible land management practices could evolve.
Except for certain coastal cities, most municipal plants have
special facilities for concentrating, digestion, dewatering, stock
piling and dumping which represent large investments.
Assuming ocean disposal and incineration are tentatively
shelved, a number of large cities or metropolitan areas should be
seeking land disposal sites. Unfortunately, suburban develop-
ments preclude such sites being close at hand. Additionally, the
land will be sufficiently costly that strong efforts will be made
for sludge loadings at the "disposal" level rather than at the
reclamation level.
Sludge pumping will be proposed for large areas handling
large single sources, whereas for small land sites and/or smaller
plants dry cake transport may prove more feasible. Consequently,
sludge handling and/or preparation at various waste treatment
plants of necessity will differ.
Known waste-solids treatment processes usually are designed
for a) reducing sludge volume and b) destruction or stabilization
of such solids. Four basic processes are used: a) concentration,
b) digestion, c) dewatering and d) heat drying and combustion before
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final disposal. The problem of disposal of a particular sludge or
solids residue requires the professional to make several major
decisions in arriving at the most economical solution. Once he
has evaluated the available possibilities for disposal of the final
residue, he must determine which combination, if any, of the four
major procedures will furnish an optimum solution.
The characteristics of a specific waste residue will control
in large measure the success or failure of handling of such residues
Perhaps the best example I can give is my experience with the
Zimpro process while I was at the Metropolitan Sanitary District
at greater Chicago. Here, we had a process that was capable of
total destruction of all organic matter in the sludge solid feed.
What would be better than having a capability of destroying all
organic matter? The rub was we were left with waste solids and a
liquid by-product that exhibited some very annoying characteristics.
For example, the process itself produced as part of its residue
a suspended mixture which looked and poured like coffee until a
concentration as high as 42*5% solids was reached. One can readily
appreciate the difficulty of concentrating to this level in order
to obtain separation and the costs involved. Another portion of
the residue was so abrasive that our pump impellers would be com-
pletely eroded within a very short period of time. Additionally,
our Utopian destruction of organic matter produced new liquid
by-products with extremely high pollutional load characteristics
which required recycling for further treatment.
Sludge treatment processes and methods of final disposal
can be classified as follows:
A. concentration
1) Clarifier thickening
2) Separate concentration
(a) gravity thickening
(b) floatation
(c) centrifugation
B. Digestion
1) Aerobic
2) Anaerobic
C. Dewatering
1) Drying beds
2) Lagoons
3) Vacuum filtration
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D. Heat drying and combustion
1) Heat drying
2) Incineration
(a) multiple hearth
(b) fluid solids
3) Wet oxidation
E. Final sludge disposal
1) Landfill
2) Soil conditioning
3) Discharge to sea
Ironically, if one is to consider only the above most widely
used methods, it is possible to arrive at approximately 900 process
combinations for sludge residue treatment and disposal. The success
of the overall sludge disposal system depends on how well the various
processes are integrated to meet economically the disposal require-
ments for a particular situation.
In municipal waste treatment, the raw preliminary solids and
the subsequent biological flocks from the secondary system can vary
considerably from plant to plant. The biological sludges are
bulky and do not concentrate as well as preliminary solids. Some
of the important factors which control the final solids, concen-
tration produced is the initial concentration of the sludge to be
thickened, the density of the particle, their size and shape, the
temperature and the age of the sludge, ratio of organic to inor-
ganic and, for activated sludge, the design of the process itself.
The aim of solids concentration is to produce as thick a
sludge as possible. However, it is not always desirable to achieve
a solids concentration in excess of 10% since these sludges are
difficult to pump. Experience shows that solids concentration
prior to dewatering is not considered a benefit to the drying pro-
cess itself, such as for drying beds. However, solids concentration
may be of significant benefit to mechanical dewatering. These are
just a few examples of what is being done to prepare waste solids
for ultimate disposal. More importantly, we must recognize the
fact that a uniform product will be the exception rather than the
rule.
Let us make a more in-depth examination of composition aspect.
Table I shows the constituent concentrations present in two liquid
sludges from very large municipal systems having the same water
supply. The wastewater entering these two plants are quite weak
even though sizeable industrial loadings are involved. The resul-
tant constituent concentrations are not considered excessive under
the circumstance. However, the contributions of copper, zinc,
chromium and lead are certainly worth noting. Recently, in
8
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TABLE I
Analyses on Digested Sludge Solids
Total-N
Ammonia-N
Chloride
Sulfur
Phosphorus
Potassium
Sodium
Calcium
Magnesium
Boron
Manganese
Copper
Zinc
Molybdenum
Iron
Nickel
Cadmium
Chromium
Aluminum
Silicon
Grease
Residue (1O3°C)
Sol. Salts via El. Cond .
pH
Total Alkalinity
Lead
Ash
Plant A
mg/1
1,512
528
49O
45.5
677
114
129
1,180
332
0.85
14.3
32.4
91.9
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conjunction with our land disposal study, we examined five strictly
domestic sludges and the findings are shown in Table II. Interest-
ingly, although the constituent concentrations were lower than the
municipal sludges (see Table I) they were within the same order of
magnitude.
Are we to assume that background or domestic waste sludge will
have appreciable amounts of heavy metals and as such reflect the
habits of the people exclusive of industrial contributions?
More recently, the Interstate Sanitation Commission distri-
buted its 1972 Annual Report which contains some very illuminating
results of influent and effluent constituent concentrations at all
their plants. Data (shown in Tables III and IV) was abstracted
from this report and represents the 5O% and 95% cummulative fre-
quency distribution. The primary plant data (Table III) includes
operations receiving heavy industrial contributions whereas the
aerobic secondary systems are receptors of generally weaker waste
loads. The values in parentheses indicate effluent concentrations.
The reduction in constituent levels between influent and effluent
should represent what is removed in the sludge phase.
A 2 Mgd plant or 14/MG week can expect a maximum 35,OOO gal-
lons of 3-5% digested solids per week. However, this normal
digestion operation results in a very interesting concentration
factor or roughly 4O fold. Plant influent and effluent concentra-
tion differences of as"little as .05 ppm or 5O ppb as seen in
Table IV will result in a concentration of 2O ppm in the final
liquid sludge. Therefore, very small removals of heavy metals
found in wastewater influents as shown in Table IV at 5O% Cummulative
Frequency Distributions should result in the following levels in
the digested sludge:
Copper = 2O ppm
Zinc - 32 ppm
Iron = 16O ppm
Mercury = .16 ppm
In Table V are shown the pounds/ton of certain constituents
found in various sludges. Since these represent current composi-
tion it must be assumed these are the loadings we must contend
with, and design our land disposal management practices accordingly.
In the future with strong pretreatment controls in effect perhaps
we will be able to maintain our municipal solids composition at
levels to maximize available land use and management. However, at
present we must work with what we have and the constituent composi-
tion can conceivably limit ultimate disposal applications. For
example the following factors have a bearing on eventual constituent
levels and whether a problem will arise or how the sludge must be
prepared for transport.
10
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TABLE II
Composition of Anaerobically Digested Liquid Wastewater Solids
from Essentially Domestic Waste Systems
Lakewood
pH
T.S.
T.V.S.
Ash
K-N
T.Ph.
Fe
Mn
Mg
Ca
Na
K
Cd
Pb
Cr
Cu
Ni
Zn
Al
Hg
6.9
3.7
69
31
1910
12OO
1535
0.2
124
2O2O
34
23
2
26
2
32
2
114
206
9
%
%
%
ug/g
"
it
n
n
n
ti
tt
tt
n
it
ti
n
n
ii
n
Bernardsville
7.2
4.5 %
62.6 %
37.4 %
187O ug/g
6OO
43O
7 "
13O
17OO "
2O "
40
O.5 "
2O "
O "
49 "
1.5 »
94 "
305 "
4 "
Neptune
7.2
6.6 %
43.2 %
56.7 %
2296 ug/g
2OOO "
2O48 "
19 "
119 "
353O "
280 "
36 "
1.25 "
189 "
5.6 "
54 "
2.7 "
9O »
458 "
14 "
Marlboro
7.1
3.O %
66.5 %
33.5 %
146O ug/g
960
589 "
19 "
68 "
77O "
26 "
91 "
O "
12 "
2.8 "
21 "
4 it
64 "
224 "
4 "
Grey stone
7.O
6.6
41.2
58.7
238O
5OO
96O
14
385
477O
24
74
0.5
25
2.5
68
1.7
76
934
O
%
%
%
ug/g
"
"
TI
tt
II
II
It
II
II
II
II
II
It
II
II
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Table III
Municipal Treatment Works in ISD - **
Primary Plants Influent, mg/1
Cummulative Frequency Distribution
B.O.D.
T.O.C.
T.S.S.
Or t hop ho sp hat e
NH3-N
50% 95%
2O7
92
174
5.48
16.4
52O
273
355
12
36
.70
.80
Copper
Zinc
*Chromium
*Lead
Iron
*Nickel
* Cad mi tun
Manganese
Mercury
*Silver
*Cobalt
0.10 (.10)
0.20 (.18)
<.5O (<.O5
<.2O (<.2O
1.0 (0.8)
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Table IV
Municipal Treatment Works in ISO - **
Secondary Plants Influent, mg/1
Cummulative Frequency Distribution
5O% 95%
B.O.D.
T.O.C.
T.S.S.
Orthophosphate
NH3-N
176
64
161
4.99
18.9O
325
162
327
11.13
39.0
Copper
Zinc
*Chromium
*Lead
Iron
*Nickel
*Cadmium
Manganese
Mercury
*Silver
*Cobalt
.10 (.05)
.16 (.08)
<.05 (<.05)
<.02 (<.02)
0.8 (0.4)
<.l (<.D
<.O2 (<.O2)
.1 (.1)
.0013 (.0009)
<.05 (<.05)
<.05 (<.05)
0.40 (.25)
0.54 (.26)
0.35 (.15)
<.02 (<.02)
2.3 (1.5)
0.3 (0.2)
O.O2 (.02)
0.38 (.38)
0.008 (.0059)
<.05 (<.05)
<.05 (<.05)
*Most values below lower detectable limit
**1972 Annual Report
Note: ( ) effluent concentration
13
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Composition of Municipal and Domestic Sludges
TABLEDV. RANGES IN Nb/TON
Total N
P
K
Ca
Mg
Hg
Cu
Zn
Ni
Cd
Ci
Al
Pb
Municipal
1966
195O (Two Wastes)
42 1O6 - 136
(121)
16 47 - 57
(52)
7 8-9
(8.5)
95 72 - 83
(77)
22 2O - 22
(21)
•^^•v ••_•_
16. 0 2.3 - 4.1
2O. O 6.4 - 13.0
trace trace - O.9
.13 - .94
5.O 3.2 - 7.2
72 15-16
15 1 .7 - 6.3
Domestic
1973
(Five Wastes)
7O - 1O3
(86)
15 - 65
(46)
1-6
(2.5)
51 - 144
(97)
3.6 - 11.6
(6.4)
0 - .5
1.4 - 2.1
2.29 - 6.2
.05 - .27
0 - .11
0 - .19
11 - 28
.8 - 5.7
(1.9)
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1) Land availability - Can you obtain a parcel of land with
a buffer zone to handle present and future needs?
2) Soil porosity and structure - Is the soil sufficiently
porous so that a liquid sludge can lose its free water by seepage
and evaporation within a reasonable time period?
3) Ground water quality - Is the ground water aquifer a prime
source of water supply?
4) Reclamation - What is the maximum loading per acre and
still maintain crop growth?
5) Sludge disposal - Is available land so limited that
loadings must exceed maximum levels permissable for proper crop
growth but not destroy drainability?
6) Site location - Is the disposal site within pumping
distance economically? Are right of ways attainable for force
mains and pump stations?
7) Site size - Should more than one site be needed to handle
the total load, is it feasible to pump sludge to more than one
location?
8) Plant size - Treatment plants vary considerably in size
and sludge production. Is pumping feasible for a plant producing
25,OOO gallons of 5% solids per week? 5O,OOO gallons per week?
lOOjOOO gallons per week? Or should such plants produce a dry
cake and transport by truck? Where is the cut-off point whether
to handle a dry cake or liquid sludge.
9) Temperature and rainfall - Is site location subject to
severe winter conditions and/or precipitation? Is storage or
stock piling space available at the treatment plant or disposal
site? Each have definite advantages.
It is readily apparent as we increase our loadings per acre
the economics should improve. At the same time, however, residual
constituent concentrations increase whereby land reclamation or
crop growth can be effected detrimentally. Presently, Rutgers is
investigating the impact which sludge application of 1O, 2O, and
4O tons/acre will have on soils, crops and ground water including
other environmental considerations. '
In Table VI are shown the effect of constituent magnification
for a Domestic and Municipal sludge. Please note certain assumptions
15
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TABLE VI . CONSTITUENT AVAILABILITY IN DOMESTIC AND MUNICIPAL
SLUDGES FOR
CROP GROWTH
Domestic
No/ton
Total N^1) 1O3
P 65
K 1.25
Ca 109
Mg 6.7
Hg .49
Cu 1.73
Zu 6.2
Ni .11
Cd .11
Cr .11
Al 11.2
Pb 1.4
Org. Mat. 1385
No/ton
(930)
(624)(2)
12.5(2)
1090
67
5
17.3
62
1
1
1
112
14
13,85O
Municipal
No/ton
1O6
47.3
8.0
82.6
2O
—
2.3
6.4
trace
O.13
3.2
15.9
6.3
iOOO
No/lO ton
(960)
(447)(3)
(47 )(3
826
2OO
23
64
— .
1.3
32
159
63
1O,OOO
(1)
If we assume 1O% of N available and a 1O-6-4 nitrogen-P2Os-K2O
ratio. (2) P. 25 times too much; K. 39% of need. (3) P- 18
times too much; K- 2.4 times too much. ( ) means excess.
16
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were made based upon present knowledge in that no more than 1O%
of the nitrogen would be available for plant development and that
at 1O/6/4 ratios for nitrogen, P2U5 and K2O the nitrogen would be
just adequate at a 1O ton/acre loading. However, at a ten ton
loading of domestic sludge the Phosphorous would result in a 25
fdld excess and in the municipal waste the excess would be 18
fold. Additionally, unanswered would be the fate of the excess
nitrogen. Would it be converted to nitrate and end up as ground
water contamination or released as nitrogen gas? We should
concern ourselves with the phosphate levels since experimental
evidence exists demonstrating that excessive phosphate can create
toxicity to plant growth. The various heavy metal concentrations
at the 1O ton rate are significant. At higher 2O and 4O ton/acre
applications the constituent concentrations would increase pro-
portionately and certainly must take into account a number of
factors which effect the availability of constituents for plants.
Some of these factors are
1) the rate of application and availability of a heavy metal such
as boron, copper, zinc, chromium, cadmium, lead and nickel. 2)
The total amount applied. 3) The cation exchange capacity of the
soil and base saturation. 4) The soil texture. 5) The soil
organic matter content. 6) The soil pH.. 7) Interaction of
metals such as copper and zinc or B and Mo which interact posi-
tively. 8) The crop and even the variety of the crop. If we
have to superimpose upon the above important considerations the
inherent variability of composition found in municipal waste
sludges, the task of crop management become exceedingly compli-
cated and the outlook for uniform procedures is exceedingly dim.
We must move on basis of fact before we include the benefits from
crop growth as part of the cost benefit ratio.
In light of existing constituent composition found in waste
sludges, the inherent concentration variability and the many
factors which must be considered for crop management the true
feasibility or economics of land disposal is largely unanswered.
We must remain cognizant of the complexity of the problem as it
now exists and the investigational needs before we can assess
the impact of such disposal techniques. However, we mustn't
lose sight of the potential of land disposal. In fact we might
even consider the possibility of supplementing digested sludge
with artificial fertilizers so that a more balanced application
could be achieved under certain circumstances. Adding chemicals
such as lime to tie-up some of the more toxic heavy metals which
are now present in municipal waste solids is another possibility.
In short, the practices of ultimate disposal, its management,
the economics and social implications are directly or indirectly
17
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related to the composition or the character of the material
requiring disposal. If a change in land disposal procedure
and use is contemplated a re-evaluation of the constituent
content impact and all its ramifications must be taken into
consideration. Based upon current levels it is highly probable
wrtere a constituent concentration is acceptable under one set
of circumstances it can become a significant problem under a
different set of conditions.
18
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DISPOSAL AND REUSE OF SLUDGE AND SEWAGE: WHAT ARE THE OPTIONS? *
*y
Robert B. Dean **
A broad outline of the properties of the solids present in municipal
wastewater disposal systems has been presented by Professor Kaplovsky. At
the risk of a little repetition, I want to review briefly some of these
properties and the quantities involved if we are to utilize the land for
waste disposal. The numbers I will quote will be easy to remember approxi-
mations to the more exact figures available in textbooks and in various
papers at this symposium. Table I summarizes the data in both metric and
English units for your convenience.
Each person produces about 100 gallons per day or 12 cubic feet of
sewage. This will cover 1,000 square feet to a thickness of just over
one-sixth inch. One-sixth inch a day or nearly four feet per year is a
reasonable infiltration rate for many soils. A city of 100,000 such as Trenton,
New Jersey, producing 10 million gallons a day would use 100 million square
feet or nearly 2,000 acres to dispose of its domestic sewage by infiltration.
Higher infiltration and evaporation rates are, of course, possible in good
soils and favorable climates. However, we all know areas where septic tank
drain fields are ineffective because the soil will not accept even minimal
quantities of water.
The solids in sewage amount to about 0.2 pounds per person each day.
They can be concentrated in about one-half gallon of sludge at 5 percent
* Presented at Rutgers University Symposium on Land Disposal of Municipal
Effluents and Sludges, March 12-13, 1973 (Paper 2, Part I).
**Chief, Ultimate Disposal Research Program, Advanced Waste Treatment Research
Laboratory, National Environmental Research Center, EPA, Cincinnati, Ohio.
19
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solids which contains, of course, nearly one-half gallon of water. From the
point of view of transport and disposal it is obviously easier to take care
of one-half gallon of water than of 100 gallons.
The quantity of sludge solids which can be assimilated on an acre of
land in a year is about 20 tons. Your city of 100,000 people produces 10 tons
of dry sludge solids each day so they will need about 180 acres to take care
of all their sludge. The sludge solids will be dispersed in 50,000 gallons of
water each day which is only one-half of one percent of the total wastewater
produced.
The Chicago Metropolitan Sanitary District treats over one billion gallons
of wastewater per day. They would require about 360 square miles of land for
sewage spreading or about 25 square miles for sludge spreading not including
sludge from industry, according to my estimates. The total population of
this country is over 200 million. We use about 20 billion gallons of water
a day. If all this wastewater were to be spread on the land, it would require
7,200 square miles devoted to sewage irrigation. This is an area slightly
larger than that of the state of New Jersey. Sludge from all of the people
in the United States would require about 570 square miles. This area is a
little less than that of Ocean County, New Jersey.
The use of the land for treatment and disposal of wastewater obviously
involves substantial problems in transportation but reduces the treatment
required. If good sewage treatment is practiced, our surface waters are
still acceptable places to dispose of wastewater, provided that it is clean
enough. However, surface waters are no longer acceptable places to put
sludge solids.
20
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Since this day's program is to be devoted to sludge disposal with sewage
disposal coming tomorrow, I will say very little about the treatment and
recovery of wastewaters by what has been called "The Living Filter." Treat-
ment and recovery is.one form of disposal, and a very acceptable one too,
when it confers economic benefits.
The Living Filter is, of course, the soil with the living organisms,
mostly microbial, which it contains. Soil microorganisms thrive on the •
organic matter in sludge and oxidize it to C02 in a relatively short period.
The quantity of organic matter that can be decomposed in a year depends on
many circumstances, especially climate, but it is large. We studied one
example in Texas where almost one foot of waste oil, essentially 100 percent
organic, was broken down by soil microorganisms each year (Dotson, Dean,
Kenner, and Cooke). This is a rate of 1000 tons/acre. A fraction of the
organic matter is converted to relatively inert humus but even that has a
short life in a well-aerated soil as anyone who has put peat moss on his
garden can testify. My six-foot high pile of dead leaves weathers down to
a foot by the next summer. I dig the residue humus into ray small garden
and the soil takes all I can give it. For practical purposes, however, the
rate of decomposition of organic matter does not limit the quantity of sludge
we can apply anymore than the rate of infiltration of water limits it.
When sludge is applied to the land, water drains intp the soil, is
evaporated, or is used by growing plants. Organic matter is oxidized to COp.
Inert minerals derived from the dirt on our clothes are, of course, dirt, a
synonym for soil or earth, and there is no practical limit to the quantity
we can apply to the soil. We must look among the soluble pollutants to find
21
-------
a limiting factor. Mr. Dotson will be talking about "Constraints on Sludge
Spreading," so I will not try to give his paper for him. I am indebted to him
for the factor of 20 tons dry weight of sludge per acre year which I used
earlier. This factor is based upon the ability of the soil, and the crops
growing on it, to assimilate and degrade the nitrogen present in ordinary
sludge.
Nitrogen and phosphorus, two of the three major nutrients which must
be listed on every bag of fertilizer, are the two substances which are
really recycled when sludge or sewage is applied to the land. None of
the organic matter can be absorbed by plant roots although the humus serves
a temporary function controlling the physical character of the soil. Micro-
nutrients may occasionally be supplied in useful quantities but many soils
have no need for them. In arid areas, of course, the irrigation value
of the water supplied can be significant. Even in sludge studies the best
increase in yields of corn came in dry years when the water content of the
sludge served a vital role.
Nitrogen is present in many forms in our biosphere (Figure l). Most of
it is inert and nutritionally useless in the air as nitrogen gas, N2. In
sludge we find nitrogen as organic compounds and as ammonia, NHo. Oxidation
of ammonia by microorganisms produces nitrites, N02~, which are quickly
changed to nitrates, NO ~ NHo and NO ~ are useful plant nutrients but
growing crops have a limited capacity to use them. Any excess of nitrogen
compounds over that which is taken up by the plants will leave the soil
by one of two routes. Nitrates can be degraded microbially to nitrogen gas
if organic matter is present and the soil is not well aerated. This
destruction of combined nitrogen accounts for a significant fraction of the
22
-------
nitrogen applied to the soil as fertilizer. However, when an excess of
combined nitrogen is applied to the soil some will show up in the ground
water.
Phosphates have been blamed for many of the bad effects produced when
wastewater is discharged to surface waters. If wastewater is spread on the
land, the soil minerals can adsorb almost unlimited quantities of phosphates
from the water that percolates down. Clean sand, however, has a very low
capacity for adsorbing phosphates.
Conventional sewage treatment normally removes less than a "third of
the phosphates in wastewater. Many treatment processes, therefore, have
been developed to remove phosphates from wastewater before it is discharged
or reused. All of these schemes concentrate the phosphates in the sludge
as an insoluble residue.
Phosphates in sludges, except for a small fraction bound in organic
compounds, are present as calcium, iron, aluminum, or magnesium phosphate
depending on the process used. Calcium and magnesium phosphates are
reasonably available to plants in neutral soils, and the ratio of Nitrogen
to Phosphorus applied in sludges is within the range of normal fertilizer
applications. When phosphates are removed from wastewater by precipitation
with iron or alum, however, the sludge contains phosphorus in a relatively
unavailable form. Precipitates of iron or aluminum phosphates can persist
in the soil for long periods slowly liberating their phosphorus to growing
plants. These precipitates otherwise behave like inert soil minerals
which can be tolerated in large amounts. An excess of iron or aluminum can
tie up phosphate which might otherwise be available. Some chemical treatment
of municipal wastes uses iron or alum in excess of the quantity necessary to
23
-------
precipitate phosphates but the absolute quantities of metal involved are small
relative to the phosphate content of normal soils.
We can contrast the behavior of the fertilizer elements N, P, and K as
follows: Nitrogen is used rapidly, any excess is destroyed or leached out
by ground water with a small organic fraction remaining for successive
seasons. Phosphorus is conserved in the soil and will eventually be used
by growing plants. We can say that phosphates are bad for our waters but
good for our soil. There is so little potassium in normal sewage that we
can ignore it.
A large number of minor elements are needed by growing plants in
quantities less than N, P, and K. Although most soils already have enough
of in the essential minor elements, there are many examples of soil
deficiencies which can be corrected by the minor elements contained in
sewage or sludge. Unfortunately, it is possible to get too much of a good
thing and an excess of an essential element above that necessary for growth
can produce toxic symptoms. The exact quantity of a given element that can
be tolerated in a soil depends on the plant species and strain and on the
other substances present in the soil.
Zinc is a classical example of a minor element which is absolutely
essential for plant growth but which produces toxic reactions when applied
in excess. One of the first recorded examples of toxic effects from what
was then called Sewage Farming took place at Paris, France. After several
decades of applying sewage to the land, crop yields fell off because of an
excess of zinc. Zinc gets into sewage from plumbing, paints, and especially
from the use of zinc table tops in the French kitchens. In Nottingham,
England, they apply sludge on the sewage treatment plant farm. Layers six
24
-------
inches thick are laid down, dried, plowed, and then farmed for six years
before putting on more sludge. I was told that zinc poisoning was diagnosed
on one field but was easily corrected by treating the field with lime.
Lime raises soil pH and converts most toxic metals to forms which are
less soluble and hence less available to plant roots. The toxic effects of
zinc, cadmium, copper, nickel, and lead can all be controlled by suitable
treatment with lime. Organic matter naturally present in sludge also binds
quantities of heavy metals which would otherwise be toxic.
For long term applications, the quantity of heavy metals in sewage or
sludge may limit how much we can apply to a given plot of land. Unfortunately,
we do not know nearly enough about plant tolerances and soil chemistry to be
able to predict today just how many years we will be able to continue apply-
ing municipal wastes. We do know that we can control excess industrial
discharges, such as copper from an electroplating shop, if it is economically
desirable to do so.
Salts are generally unwanted in the soil or ground water. In areas of
high evaporation, salts will accumulate in the soil from any form of irriga-
tion and unless they are flushed away they will eventually kill the soil.
Salts are a problem west of Kansas City but are seldom a problem in the East
where rainfall exceeds evaporation and the excess moves through ground or
surface waters to the sea. Salts in sewage or sludge are always greater
than in the municipal water supply, usually by a factor of two in sewage
from eastern communities. Some treatment processes significantly increase
the salt content of wastes and may therefore be unsuitable in arid areas.
Desalination is no cure except near the seacoast because the salt removed
must be put somewhere.
25
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Sludge can, of course, be stored in a landfill, preferably after most of
the water has been removed. If the landfill is properly designed, it will
be a form of permanent storage of no agricultural significance except for
a change of land contour. If the landfill is not properly designed, toxic
materials may leach out to contaminate surface and ground waters.
The soil utilizes water or passes it on to surface or ground waters.
Organic matter is destroyed by soil bacteria after it has served its purpose
as humus. Soluble salts remain with the water and are concentrated to toxic
levels only in arid areas. Nitrogen is used at once if there are growing
plants to make use of it; only a fraction is stored for later seasons and an
excess may reach the ground water as nitrates. Much of the phosphorus has
limited availability but it is all conserved by the soil for eventual use.
Heavy metals are bound in the soil where they are available for plant use
but where they may reach toxic levels. Insoluble minerals are conserved
by the soil and eventually raise the salt level.
26
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REFERENCES
Dalton, F., and Murphy, R., "Land Reclamation (at Chicago)." Presented at
Annual WPCF Conference, Atlanta, Georgia, Oct. 19T2.
Dean, R. B., "Ultimate Disposal of Waste Water: A Philosophical View," in
"Water-1969, " AIChE Chem. Eng. Prog. Symp. Ser. 6£, No. 97, 1-4
Dean, R. B., "Ultimate Disposal of Waste Water Concentrates to the Environ-
ment, " Ejv^U^nmejital^^ 1079-1086 (Dec. 1968).
Dotson, G. K., Dean, R. B., Kenner, B. A., and Cooke, W. B., "Land Spreading,
A Conserving and Non-Polluting Method of Disposing of Oily Wastes," in
Advances in Water Pollution Research: Proc. of the 5th Intl. Conf.,
San Francisco, 1970," Pergamon Press, 1971, Vol. 1, Sec. II, pp. 36/1-15.
Dotson, G. K., Dean, R. B., and Stern, G., "The Cost of Dewatering and Disposing
of Sludge on the Land," in "Water- 1972, " AIChE Chem. Eng. Prog. Symp.
Ser. 129, 217-226 (1973).
Evans, J. 0., "The Soil as a Resource Renovator," Environmental Science and
Technology M9), 732-735 (Sept. 1970).
Ewing, B. B., and Dick, R. E., "Disposal of Sludge on Land," in "Water
Quality Improvement by Physical and Chemical Processes," ed. "by
Gloyna and Eckenfelder, Jr., Univ. of Texas Press, pp. 394-1*08 (1970).
Smith, J. E., Jr., "Wastevater Solids Process Technology for Environmental
Quality Improvement, " Proc. Application of Filtration Technology in
Municipal and Industrial Water and Wastewater Treatment, pp. 1-18,
ed. by H. Nugent Myrick (1971).
27
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TABLE I
REPRESENTATIVE QUANTITIES AND AREAS FOR SLUDGE AND SEWAGE
U.S.
5. Chicago Metropolitan Sanitary District
Waste water per day
Sludge per day
For irrigation of waste-water
Spreading of sludge
Metric
1.
2.
3-
1*.
WATER
One person uses per day
or
This will cover
and infiltrate per day
WATER
100,000 people (Trenton, N.J.) use
If spread
This would cover
or
The total water per year will be
SLUDGE
One person produces per day
at 5$ solids contained in
100,000 people produce solids per day
LAND ASSIMILATION OF SLUDGE
One acre can assimilate per year
One hectare can assimilate per year
100,000 people need
100 gal.
12 cu.ft.
1000 sq.ft.
1/6 inch
10 MGD
1/6 inch
2000 acres
3.6 sq.mi.
60 inches
0.2 Ib.
0.5 gal
10 ton
20 ton
l80 acres
too i
. f)
O.U m3
100 m2
U mm
to, 000 m3/day
4- mm
1,000 hectare
10 km2
1,500 mm
0.1 kg
2 1
9 Ton
45 Ton
70 Hectare
1 Billion gallons U x 106 m3
1000 ton 900 Ton
360 sq.mi. 1,000 km2
25 sq.mi. 70 km
THE USA - WATER -
6. 200,000,000 people use per day 20 Billion gallons 80 million m"
Irrigation would require 7200 sq.mi. 20,000 kn
This is a little more than the area of New Jersey
THE USA - SLUDGE
7. 200,000,000 people produce per day
Spreading would require
This is a little less than the area of Ocean Co., N.J.
DECOMPOSITION OF ORGANIC MATTER (oil)
8. In Texas soil, per year 1 foot
Per acre year 1,000 tons
Dotson ct al., 1971
20,000 tons 18,000 Tons
570 sq.mi. 1,500 km2
30 cm
900 Tons
28
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THE NITROGEN CYCLE
rsan
3
FIGURE 1
29
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See APPENDIX for fact sheet on movie presented
"Irrigation of Liquid Digested Sludge"
30
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I/
SOILS AS SLUDGE ASSIMILATORS
by
21
James 0. Evans
Introduction
In August, 1967, on my first assignment as Research Soil Scientist
in Ultimate Disposal Research at the Advanced Waste Treatment Laboratory,
Cincinnati, Ohio, I spent two weeks in Pennsylvania touring sewage
treatment plants and studying sludge disposal methods. About 30
Pennsylvania municipalities were spreading digested sludge on rural
lands.
Although I was slightly knowledgeable about a few effluent disposal
operations in different parts of the country, I knew nothing about sewage
sludge before going to Cincinnati. Consequently, I was not prepared
for the experience I was,to undergo in Pennsylvania. I went there highly
skeptical of the sludge-on-land disposal practice and came away a convert.
I observed sludge being spread and saw previously sludge-treated lands
representing a range of soil types and topographic and- land-use conditions
from the Allegheny Mountains of north central Pennsylvania to the highly
productive farm lands of the lower Susquehanna Valley in southeastern
I/ Presented at the Symposium on Land Disposal of Municipal Effluents
and Sludges, Rutgers University, New Brunswick, N. J., March 12, 13,
1973.
II Research Hydrologist, Division of Forest Environment Research, Forest
Service, U. S. Department of Agriculture, Washington, D. C.
31
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Pennsylvania. I found it difficult not to be convinced by what my
eyes saw, my nose did not smell, and my ears heard from the enthusiastic
farmers who were spreading sludge on their pastures and croplands. My
impressions were summed up in the article, "They spread 'black gold'
on their fields" which appeared in the February 10, 1968, issue of
the Pennsylvania Farmer. The expression, "I call it black gold" was
used by one farmer in Elk County when asked to give his opinion of the
digested sludge he was receiving free of charge from the St. Marys sewage
plant.
Despite my "conversion," I found it difficult to persuade others
that land disposal of sludge was good and that sewage sludge really
wasn't an ugly odorous waste, but instead was a valuable resource which
should be recycled on land at every opportunity. Skeptics often serve
a very useful purpose, and I quickly discovered I had no factual answers
to many questions raised about the feasibility of disposing sewage wastes
on land. So I searched the literature and initiated some studies, but
today, nearly six years later, I still know few, if any, answers to the
more perceptive questions posed by my skeptical colleagues. I cannot
help but be pleased, however, by the current upswell of interest in land
disposal, and the growing numbers of converts help to bolster my faith
in the cause.
"Soils as sludge assimilators"—should you think this is a simple
subject, I hasten to disagree. Since one could not adequately cover
this very important topic without writing a book, I am suggesting here
32
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only a list of factors to be considered in locating and managing a site
for sludge application. First I shall outline several soil properties
that promote or facilitate sludge assimilation. Brief discussions on
application techniques, on significant observations made by several
investigators, and on the assimilation and deactivation of pathogenic
organisms in sludge treated soils will follow. Then, I shall discuss
the topic of soils as sludge assimilators under three main headings—
physical factors, chemical factors, and biological factors.
Soil Properties that Facilitate Sludge Assimilation
Which of the soil properties relate most significantly to soil
capacity for sludge assimilation? One may designate at least four soil
properties as extremely important to the use of the soil as a disposal
medium, (l) ion exchange capacity (or adsorption capacity), (2) buffer
capacity, (3) filterability (filtration capacity), and (4) microbial
transformations (!_).*
Ion exchange capacity| alludes to the total amount of cations and
anions that are sorbable per unit of soil weight. Most soils have
moderate to large cation exchange capacities (CEC) but only limited anion
exchange capacities. For simplicity we will consider here only CEC.
Soil CEC is the sum of both the organic and inorganic soil components.
The ability of a soil to retain metals derived from a sludge source and
to keep them out of ground and surface water and out of plant tissues is
largely a function of its CEC.
* Note: Underlined numerals such as (1_), above, refer to citations
at the end of the paper.
33
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The huffer capacity of soils is derived from several sources.
Buffering tends to restrict rapid changes in solution pH. Carbonate
soils buffered to a pH of 7 or above tend to bind wastes and inhibit
solubility of heavy metals.
Soil filterability refers to soil efficiency as a physical filter
of suspended particles. Filtration of pathogenic organisms from
sludge sources is an important element to successful use of sludge.
Permeable soils of intermediate texture which have enough colloidal
content to trap particulatos are probably the best fillers.
Microbial transformaLions involve utilization of soil microflora
to transform certain of the major elements essential to plant growth,
e.g., nitrogen, phosphorus, sulphur, and carbon.
Application Techniques
"Modes of Transporting and Applying Sludge" is the subject of another
paper prepared for presentation at this symposium, so it appears prudent
to say little here about application techniques. We should recognize,
however, that the manner by which sludge is applied may greatly affect how
it is assimilated. Spray irrigation of liquid sludge may be the best and
most practical application technique in most cases. But each situation
should be evaluated independently. Furrow application should work best
in some cases. (For example, application between rows of trees or other
vegetation planted along contours of steeply sloping land.)
Land spreading may be accomplished in several ways such as by
overland gravity flow, by gravity sprinklers from a moving vehicle, and
by various pressure ejection methods. The sludge may be left on the soil
or soil-vegetative surface or plowed under. It may be ejected
34
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under the soil surface at various depths. In general, metabolic activity
is maximized by surface sludge applications; however, dangers of
contaminating surface waters and aesthetic objections are least with
subsurface treatments.
This paper presents general concepts concerning factors which
determine the relative ability of soils as sludge assimilators. Some
readers might prefer receiving an itemized listing of facts and figures
or specific detailed guidelines and work documents concerning sewage
irrigation and sludge spreading on land. Certain general guidelines
and documents do exist but are of limited value due to a paucity of
scientific data. An application guide was developed in July 1971 by
the Forest Service for north central and northeastern forest lands,
and earlier, in January 1971, a problem analysis on land disposal of
sewage was prepared by Forest Service Research. The Bureau of Water
Quality Management, Pennsylvania Department of Environmental Resources
published a sewage and industrial waste water spray irrigation manual
in 1972, and USDA's Agricultural Research Service is cooperating with
the Soil Conservation Service in developing a guide on land disposal
of sewage and farm animal wastes. Other guides probably exist and
certainly each is of some value. If a series of charts were available
showing when, how, and how much of a particular kind of sludge can
safely be applied to various soil types under various land, vegetative,
climatic, and topographic situations, this subject would require no
comment, and this symposium would not be needed. In short, there would
35
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be no unanswered question about sludge disposal on land. But, unfortu-
nately, such is not the case, and it is imperative that we expand our
knowledge rapidly in this crucial area. In order to do so, however,
we must learn more about physical, chemical, and biological influences
and application techniques.
Significant Observations by Several Investigators
Several opinions and statements concerning sludge assimilation
have been reported which are highly instructive. E. G. Coker (2)
of Great Britain has stated, "It is fair to say that almost all of the
ill-effects of sludge application arise from over-heavy or excessively
frequent applications." In this connection, Dr. T. D. Hinesly (3_) of the
University of Illinois concluded that, "Nitrogen contained in digested
sludge is the most immediate limiting factor to rates of application.
Our data indicates (sic) that about 2 inches of (liquid) sludge would
satisfy the nitrogen needs of non-leguminous crop (sic) without
producing excessive nitrate in percolated water " Concerning nitrogen
loadings Mr. Coker observed that, "The response (of selected grasses and
cereals) to applied nitrogen falls off above about 300 Ibs/acre/year,
applied at about 100 N per application."
Some investigators believe certain of the heavy metals are limiting
factors to land application of sludge. The availability of these trace
elements may be the key issue. Coker notes that availability depends
on several factors including: (a) Soil organic content—"The
higher the organic content the more firmly they (heavy metals) are
held;" (b) the level of pH—a pH of 6.5 or higher tends to minimize
36
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toxic effects of excess heavy metals; (c) soil drainage—Solubility of
heavy metals is enhanced by poor drainage and reduced in well-drained
soils. On the other hand, Coker (2_) mentioned trees flourishing on a peat
swamp containing up to 7 percent copper in dry matter. He suggested
that anaerobic conditions in this case might have caused precipitation
of (copper) sulphide.
Consideration must be given to conditions resulting from the
occurrence of two or more metals in toxic concentrations. Coker has
stated that, "If a number of motals arc present it is considered that the
toxicity of them is additive, providing the differing toxicity of metals
is taken account of during addition." One might counter that possible
synergistic effects and counteractive or antagonistic effects should also
be thoroughly investigated. Research concerning heavy metals has been
done by Hinesly and his coworkers at the University of Illinois (4), by
W. H. Allaway, U. £.. Department of Agriculture (5), by J. R. Peterson of
the Metropolitan Sanitary District of Greater Chicago (6), and by a
number of other investigators. Available data suggests the metals
problem has at times been exaggerated.
Pathogenic Organisms in Sludge-treated Soils—Are they Effectively
Assimilated and Deactivated?
Since the problem of pathogens in sludge-treated soils is related
primarily to sludge rather than soils, so far I have not discussed
pathogens. I now briefly address this important subject. Peterson (7)
stated that well stabilized sewage sludges are generally free of odors
and pathogens. Perhaps his statement should be amended to read
"objectionable odors." I question his assertation concerning sludge
37
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being "generally free" from pathogens. Let us hope he is right, but
there are many investigators who are fearful of the pathogen spectre.
In his paper, Peterson cites several studies which show that aerated
soils and sunshine work together quite effectively in reducing and
subsequently eliminating pathogen populations. Whatever the problem,
it does not appear to be unsolvable. Lime additions seem to be effective
in destroying pathogens present in sludge. Also, the use of ozone and
pasteurization processes are under investigation as possible feasible
means for eliminating potential pathogen hazards.
I now refer to three factors for consideration in evaluating soils
as sludge assimilators.
Physical Factors Relating to Sludge Assimilation by Soils
a. Sludge characteristics
Soil infiltration and absorptive rates are altered by sludge
treatments due to the nature and concentration of undissolved solids in
sludge. Most unthickened liquid sludges contain no more than 5 percent
solids by weight (normally between 2 and 4 percent solids), and can
be spray-irrigated without difficulty. Consideration has been given by
some planners to spray irrigate sludges of up to 15 percent solids
content; however, a solids content of 10 percent probably should not
be exceeded. In addition to difficulties encountered in pumping and
spraying or ejecting thickened sludges, there may be problems in
achieving acceptable infiltration and percolation rates into and through
surface layers of most soils. Therefore, unless mechanical incorporation
38
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of the solids is an integral part of the treatment, the ability of the
soil surface to receive and transmit liquid sludge is a controlling
factor to sludge application rates. If, however, the application
technique involves spreading sludge in a semi-solid state or
incorporating it in soil by some other method, such as the trenching
method used by Agricultural Research Service scientists at Beltsville,
Maryland, sludge thickness or percent solids content may not be a
limiting factor. Also, since soils must absorb less water from
application of semi-dewatered liquid sludge than from that of an equal
volume of thin sludge, more of the thicker sludge (dry weight basis)
might be assimilated by soils of limited water absorptive capacity.
There is a need for factual data on the effects of various sludge
loadings on the infiltration and percolation rates and assimilative
capacities of different soils.
b. Physical soil characteristics
Porosity, structure, grain-size distribution (texture), and
mineralogy are important physical factors in evaluating soil
capability for sludge acceptance. (Mineralogy is, of course, also a
chemical characteristic.) Soils can vary drastically, and an arbitrary
group of soils (each soil being of similar construction) can be expected
to respond quite differently to treatments and management from that of another
39
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i/
distinctly different group of related soils* The wide variability
among certain soils indicates some can readily assimilate large amounts
of certain sewage sludges while others can assimilate only small amounts,
Suitable soil and crop management may compensate for or amend limiting
soil properties, however. Planners have an obligation, therefore, to
be knowledgeable about significant soil conditions before development
plans are made. Sites may be selected where soils favorable for sludge
assimilation occur. Assistance can be obtained from the U. S. Soil
Conservation Service, County Agents, and State and Federal forestry
soil scientists.
I/ It might help to better visualize and understand how much soils
differ by considering why they differ. Soils differ because of
variations in the following five "soil forming" factors: (1) The
parent material (nature of rock or mineral deposit from which the
soil is derived), (2) climate (temperature and precipitation amounts
and extremes), (3) topography or relief (involving surface slopes
and natural drainage considerations), OO living (and dead) organisms
(movements and accumulations of various vegetative and other macro-
and micro-organisms on and within land surfaces), and (5) time (or
age) (time is considered not just a chronological period, but a
value that reflects the intensity of soil development exerted by
factors 1 through 4 during the length of time they have been in
operation—"old" soils showing more development than "young" soils).
None of the factors act independently, of course. Each may affect
or modify the other, and developed soils reflect the interrelated
and interdependent influences of all of them. This paper is not a
dissertation on soil genesis, but a basic understanding of the
factors that produce soils—that cause them to differ so drastically
from one environment to another distinctly dissimilar one (or cause
them to be the same in near identical environments)—helps one to
better comprehend the great variability that exists across the soil
spectrum. This knowledge leads one to anticipate vastly different
responses from unlike soils when they are subjected to certain land-
uses and treatments.
40
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Few soils are unsuitable for sludge disposal. Those soils most
likely to be unsuitable are: (1) extremely coarse-grained soils
(coarse sands and gravel), (2) extremely fine-textured soils (such
as montmorillonite clays), (3) very shallow soils (to water, bedrock,
impermeable layers, or gravel), (4) wet, undrained soils, (5) frozen
soils, and (6) solonetz and other sodium saturated soils. The suitable
soils (the vast majority of all soils) may vary greatly in relative
ability to assimilate sludge, however.
c. Climatic influences
Climate plays a powerful role in determining the nature of
soils, but I see no need to stress the influence of climate on sludge
assimilation by soils. Briefly stated, and eliminating other variables,
assimilation is aided by warm, moist to dry climates and retarded by
cold, wet climates. A climate should not be too hot or dry, however.
Death Valley might be an ideal spot for sludge disposal, but the local
soils would make very poor sludge assimilators. Furthermore, dry
climates may cause salt accumulations.
d. Land influences—relief
As a soil forming factor relief may strongly influence
certain aspects of soil development such as internal makeup and soil
depth. With respect to sludge application, relief involves two
principal considerations. One is steepness of slope. To prevent
runoff on strongly sloping lands, the rate of liquid sludge application
41
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should not exceed the soil infiltration capacity and percolation rete.
Otherwise, terraces or other costly structures or land treatments
involving extensive use of vegetative mulches would be required to
prevent sludge runoff. (Forested hillsides with controlled runoff
might be highly efficient for sludge treatment-disposal, however.)
The second major consideration involves either flat land or depressional
areas which are conducive to ponding if the soils either are very
slowly permeable or presaturated. Relief also may strongly affect
the mechanics of sludge application. Certain current application
methods might range from difficult to impossible to implement on
various steeply sloping or strongly dissected land areas.
e. Biotic influences
Living and dead biota (flora and fauna) influence the physical
assimilation of sludge by soils. First, briefly consider vegetation
with respect to: (1) Physical presence on the land. Trees or other
densely growing plants will partially intercept spray applications and
may act as physical barriers; (2) Physical activity within the soil.
Some root systems are deep and others are shallow. Deep systems promote
drainage and the development of deep soils. (Roots may exert powerful
disruptive forces on subsoils.) Some root systems are large in size
while others are finely divided or fiberous. (Fiberous systems promote
good surface structure.) Hence, physical absorption of sludge will vary
according to prevailing root systems; (3) Short term, immediate effects
on soil infiltration and absorptive capacity. Infiltration can be
rapid through a grass sod but slow through a bare," crusted surface of
42
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the same soil type. Percolation may cease in the frozen soils of bare
lands or meadows but proceed well in the unfrozen protected soils of
an adjacent forest.
Both large and small animals profoundly affect soil physical
conditions which in turn may largely determine sludge absorptive
capacity. Burrowing animals break up and aerate dense soils; large
land animals may trample and compact soils and may destroy protective
cover vegetation. Also, burrows, cracks, and root channels may
facilitate direct drainage to shallow groundwater and "short circuit"
the soil filter system.
f. Physical loading rates
Perhaps the key to a successful sludge disposal program is
an understanding of how much of, and when, a given sludge should be
applied to a particular soil or land area. Almost any soil at some
time is capable of assimilating a small amount of sludge, but any soil
can be overloaded. Attempts at economy are likely to lead to overloading.
Overloading some aspect of the assimilation process is the cause for
failure in any malfunctioning land disposal system.
Chemical Factors Relating to Sludge Assimilation by Soils
Chemical factors are as important as physical factors in respect
to the assimilation of sludge by soils. The chemical nature of both
sludges and soils should be considered.
a. Sludge chemical analysis
Sludges are known to greatly differ chemically; furthermore, the
chemical nature of sludge from an individual treatment plant may differ
43
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considerably from day to day as determined by (1) the nature of the
sewerage input and (2) treatment plant operating capabilities and
conditions. Table 1 shows chemical analyses of sewage sludges from
seven waste water treatment plants. Note that at the Hastings,
Minnesota plant and at all of the Chicago plants, total nitrogen
content in the sludges is comparatively high whereas the ammonia-
nitrogen (NHi|.-N) content is high at only those plants without supernatant
digester drawoff. Note also that the iron content is high in the FeCls
treated West-Southwest sludge, whereas the lime treated Denver sludge
is calcium enriched.
Whether a sludge is judged as "good" or "bad" may depend as
much or more on its intended use as on its chemical make-up. But one
should be able to identify and evaluate potential troublemakers when
they occur in relatively high concentrations. Cadmium, chromium,
copper, boron, zinc, mercury, nickel, and lead are commonly recognized
as potential troublemakers.
What about nitrogen and phosphorous? Whether they are "good" or
"bad" depends greatly on whether they are considered as needed fertilizer
or as wastes requiring safe disposal. Certainly with nitrogen, and
also with certain other elements and compounds, there can be too much
of a good thing. We must recognize and remember that sludge analyses
are quite important—they are essential to the development of ecologically
• sound and environmentally safe guidelines and plans for sludge disposal
on land. Sludge analyses should be evaluated in light of the chemical
-------
Table 1. Chemical Analyses of Sewage Sludges from Various Wastewater Treatment Plants.
Source :
Treatment
Process :
*-
<_n
Analyses
N-Total
Ntfy-N
P
K
Ca
Mg
Zn
B
Fe
Mn
Al
Cd
Cl
Cr
Cu
Ni
Pb
Hastings ,
Minn.
Primary and
. waste acti-
vated : an-
aerobic
digestion
without
supernatant
drawoff
(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
0.12
<0.001
0.039
— M.<
St. Paul, Hanover
Minn.
Primary £ Primary (
waste acti- activatec
vated (1:2): Anaerobic
undigested without 5
digester
(2) (3)
9- ^^,r
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
0.065
0.015
0.070
"O u.i y
5.57
3.63
2.59
0.68
5.05
1.64
0.069
2.22
0.07
0.0089
0.12
0.019
0.062
0.032
0.083
S.D.G.C.t Cl
Calumet
I waste
1:
: digestion
supernatant
drawoff
(4)
wt. basis
5.20
2.40
3.90
0.55
4.20
0.60
0.35
3.68
0.14
1.21
0.0125
0.74
0.112
0.088
0.020
0.18
licago, 111.
West-Southwest
Waste-activated
FeCl3 addition:
vac. filtered:
Heat -dried
(5)
6.37
trace
2.49
0.41
1.4
0.75
0.002-0.04
5.32
0.012
0.028
0.362
0.11
0.034
0.141
Denver, Colorado Athens, Ga.
: Primary £ waste- Primary:
activated: FeClg Anaerobic
and lime: vac. digestion
filtered : undi-
gested
(6) (7)
4.57
1.75
7.38
0.45
0.172
0.00022
1.48
0.0253
0.0324
3.5
0.75
0.22
1.21
0.09
0.252
0.00199
0.0199
0.046
0.0026
Reference: Peterson, J. R., et. al. (See Citation No. 7)
"Metropolitan Sanitary District of Greater Chicago
-------
constituency of the soils on which they are to be applied. Sludge
additions could aggravate a bad condition. Conversely, sludge may act
as a soil amendment. For example, sludge from sewage treatment plants
serving industrial areas of Chicago has been used to reduce both acidity
and the availability of heavy metals in coal mine spoils of the Palzo
tract of the Shawnee National Forest in southern Illinois (8).
b. Soil chemistry
We must not overlook the importance of the chemistry of the
soil. Heavy metals occur naturally in soils. They often are called
trace elements within the soil matrix. (Many are essential to plant
growth and are needed in appropriate amounts.) Soil chemistry alone
will seldom determine whether a particular land area is a suitable
sludge disposal site, but it may well often determine relative suitability.
Pertinent chemical factors include soil pH and calcium reserve, percent
sodium saturation, boron content, iron and aluminum content, and kind
and percent of soluble salts. In brief, here are several examples of
the importance of soil chemistry: (1) Sodium-saturated soils including
sandy, granular soils may be virtually impermeable to water; (2) even
in minute amounts in soil, boron is highly toxic to most vegetation,
consequently, small amounts in sludge may be critical on marginal soils
in arid and semi-arid climates; (3) a definite potential for groundwater
pollution with nitrate-nitrogen (NOg-N) exists in portions of the
Northern Great Plains, dependent on management practices and on distribu-
tion of precipitation and other factors influencing the depth of soil
wetting; (4) relatively large concentrations of phosphate may leach
46
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from calcium enriched soils derived from limestone-phosphate mineral
(apatite) deposits, particularly if organic matter is added.
c. Climatic influences
As for climate, let us consider it here only as it modifies or
influences the chemistry of sludge-soil contact and interaction. As
previously mentioned in relation to sludge assimilation, warm and
moist conditions promote or accelerate interaction, whereas cold, dry
conditions inhibit actions and reactions.
d. Drainage influences
Drainage is intimately related to soil and climatic influences
mentioned above. At this point, however, it is appropriate to project
our thoughts on soil aerobic vs. anaerobic conditions as influenced by
drainage and resultant chemical changes. Good drainage promotes aerobic
conditions; impeded drainage leads to anaerobic conditions. In general,
aerobic soil conditions are necessary for satisfactory sludge assimila-
tion. On occasion, however, we may wish to promote anaerobic conditions
within the subsoil to inhibit nitrate production or to induce denitrofi-
cation as a way of reducing nitrate pollution of groundwaters. A
combination of heavy sludge loadings and impeded soil drainage may result
in undesirable conditions where hydrogen sulfide gas and other offensive
smelling substances are produced and in the mobilization of some metals
and nutrients.
e. Biotic influences (biological actions)
Numerous biological actions directly and indirectly affect
the chemistry of soils and thereby the ultimate assimilation of applied
47
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sludge. We might reflect briefly on a few of these actions. Consider
vegetation for a moment. Each vegetative type tends to exert a
characteristic and unique influence on the soil environment. By
exerting different kinds and degrees of physical forces, various root
systems differentially affect soil weathering, aeration, drainage,
soil chemistry, and subsequent biological activity. Roots excrete
organic acids. The litter from different tree species directly affects
soil pH and nutrient accumulation vs. nutrient leaching.
Earthworms, burrowing insects, and other soil organisms mix and
aerate soils, produce organic slimes and excrement, and eventually die;
they are an integral part of the recycling process and directly and
indirectly alter physio-chemical conditions, pH, nutrient status, and
sludge assimilation.
Biological Factors Relating to Sludge Assimilation by Soils
We have just taken a brief glance at general biological influences
on soils and soil chemistry. Now we should take a closer look at certain
of the biological faccors and how they operate.
a. Micro-organisms
The role played by micro-organisms in sludge and soil in
promoting assimilation and stabilization and in creating a favorable
environment for sludge utilization by higher organisms can hardly be
overemphasized. It is also an area in which considerable research is
sorely needed.
Although much progress has been made during the last decade, we
have much to learn about the role played by micro-organisms in determining
48
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micronutrient status, about interrelations between soil humus and
micro-organisms, and about chelation in soils. For example, we know
that the quantity of micronutrients held in the solution phase as
individual ions and as soluble metal-chelate complexes is influenced
by the activities of micro-organisms and higher plants, but we need
to know more concerning why, how, and how much. We also know it is
important that trace metals that would ordinarily convert to insoluble
precipitates at the pH values found in productive agricultural soils
are maintained in soil solution by chelation (9).
Let us consider mycorrhizae organisms for a moment. Mycorrhizae
are symbiotic associations in which the smallest order of secondary
roots are invaded by specific fungi during periods of active root
growth, and without these fungi, most plants, including important
forest and horticultural species, could not survive in the dynamic,
highly competitive biological communities found in natural soil
habitats (10). Dr. Donald Marx, a Forest Service research soil scientist
at the Southeastern Forest Experiment Station project location in
Athens, Georgia, is conducting some promising studies on the use of
mycorrhizae and sewage sludge to improve the physical, chemical, and
biological conditions of eroded, nutrient-depleted, unproductive soils
in Georgia and Tennessee.
b. Macro-organisms
Activities of certain of the larger organisms, the readily
visible ones, such as earthworms, insects, burrowing animals, land
animals, grass, and trees, have already been alluded to. They exert
49
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great effects on soils physically, chemically, and biologically
through their physical activity, respiration, excretion, evapo-
transpiration (by vegetation), reproduction, and death and decay.
Concluding Statements and Recommendations
Should land application of sludge really catch on, it might become
feasible to control the nitrogen content of sludge through waste
treatment plant processes to make a product suitable either primarily
as a source of nitrogen fertilizer or for high rates of disposal as
a low-nitrogen soil conditioner.
I reiterate that overloading is the prime cause of land disposal
malfunctions. Although on occasions the metals problem appears to
have been exaggerated, I agree with Coker (2) that "it is of the greatest
importance for the chemical engineer to develop cheap effective methods
of removing heavy metal effluents before they are absorbed (and adsorbed)
on the sludge organic matter . . . ."
Perhaps even more importantly toxic metals and chemicals should
be removed (and reused when feasible) before discharge with sewerage
into waste treatement plants. Then safer residues would result and
we would be a lot less concerned about the ability of soils to assimilate
sewage sludge.
50
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CITATIONS
1. Routson, R. C. and R. E. Wildung. 1969. Ultimate disposal of wastes to soil,
Water—1969. Chemical Engineering Progress Symposium Series.
American Institute of Chemical Engineers, Vol. 65, No. 97:
19-25.
2. Coker, E. G. 1967. Utilization of sludge in agriculture. In
Sludge Treatment and Disposal - Proceedings of the Symposium
on the Engineering Aspects of the Use and Reuse of Water.
Institution of Public Health Engineers. Municipal Publishing
Company, Ltd. 136 p.
3. Hinesly, T. D., D. 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
Protection Agency. 61 p.
4. Hinesly, T. D., E. L. Ziegler and R. E. Jones. 1972. Effects on
corn by applications of heated anaerobically digested sludge.
Compost Science. July-August: 26-30.
5. Allaway, W. H. 1968. Agronomic controls over the environmental
cycling of trace elements. Advances in Agronomy. Vol. 20:
235-274.
6. Peterson, J. R., T. M. McCalla and G. E. Smith. 1971. Human
and animal wastes as fertilizers. Fertilizer Technology and Use.
2nd edition. Soil Science Society of America, Madison,
Wisconsin.
51
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7. Peterson, J. R., C. Lue-Hing and D. R. Zenz. 1972. Chemical and
biological quality of municipal sludge. Symposium on Recycling
Treated Municipal Waste Water and Sludge Through Forest and
Croplands. The Pennsylvania State University, University Park,
Pa.
8. Anonomous. 1972. Draft environmental statement, Palzo Restoration
Project. Shawnee National Forest, Forest Service, USDA, 64 p.
9. Stevenson, F. J. 1972. Role and function of humus in soil with
emphasis on absorption of herbicides and chelation of
micronutrients. BioScience Vol. 22, No. 11: 643-650.
10. Hacskaylo, E. 1972. Mycorrhiza: The ultimate in reciprocal
parasitism? BioScience Vol. 22, No. 10: 577-583.
52
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MODES OF TRANSPORTING AND APPIYING SLUDGE
W. J. Bauer, President
Bauer Engineering, Inc., Chicago, Illinois
Subsidiary of
Diversified Earth Sciences, Inc.
Los Angeles, California
Paper presented to the seminar on Land Disposal of Municipal Effluents
and sludges, sponsored by Region II of the U. S. EPA, and held at
Rutgers University on March 12 and 13, 1973.
Introduction
Sludges resulting from treatment of municipal sewage are usually
difficult to dewater so that transportation and application problems begin
with considerations of just how much effort to expend on dewatering.
The purpose of this paper is to discuss alternative methods for dewatering,
transporting and applying of these sludges, with a view to stimulating the
thinking of engineers concerned with the constructive use of this valuable
resource. The discussion is presented from the standpoint of a practicing
engineer who has been closely involved in excavating, transporting and
applying to land over a half million wet tons of sludge slurry from the
Metropolitan Sanitary District of Greater Chicago. The sludge was trans-
ported by unit train for distances up to 170 miles from Chicago. Applica-
tion was performed by several different techniques, as will be discussed
herein. Alternative transportation systems are also discussed, including
truck, rails, barge, and pipeline.
Types of Sludges; Physical Characteristics
Sludges can be primary or secondary, digested or undigested,
or various combinations. Although their chemical and physical character-
istics vary widely, for purposes of this paper these variations will be ignored
53
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The undigested sludges generally call for minimizing exposure of
the sludge to reduce the possibility of anyone being offended or believing
that he has been offended by an odor. Because of the widespread belief
that all sludges do have an odor, it is also generally a good idea to
handle digested sludges in the same manner. For that reason, the methods
of sludge application which provide the least visibility of the sludge itself
are recommended as the preferred practice.
The differences between sludges are sufficiently marked to warrant
tests of both chemical and physical properties before final design of the
handling facilities. The chemical characteristics are being dealt with by
others at this seminar, so I shall confine my comments to the physical
characteristics which affect transportation and application costs.
Costs of Dewatering
Sludges to be handled have solids contents ranging from 1% to 100%,
the latter being heat dried sludges. The costs of dewatering vary widely
depending upon the particular sludge and technique being used, but some
generalizations will be made to illustrate basic concepts of how the desir-
able per cent solids for a given situation can be analyzed.
The following fundamental assumptions will be made regarding costs
of dewatering:
Resulting per Dewatering
Method cent solids Cost/dry ton
Lagoons, plus excavation
Vacuum filter
Centrifuge
Filter press
Vacuum filter 4 heat drying
15%
25%
30%
40%
99%
$15
16
20
30
100
54
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The actual costs for these processes vary considerably with the
particular situation which pertains to a given case, and should be speci-
fically determined for that case. The figures given above are merely to
be used in this paper in the examples given to illustrate the alternatives
to be examined in designing transportation and application systems.
Hydraulic Characteristics. The hydraulic characteristics of sludges
vary considerably also with the per cent solids. Fig. 1 illustrates the
variation of the apparent Darcy f as a function of per cent solids for a
given temperature, grease content, entrained air contents, etc., but for
the sake of simplicity, we shall in this paper use the simple curves of
Fig-1 as guidelines for the illustrative examples given. Sludge (A) is a
hypothetical example of a secondary sludge, and Sludge (B) is a hypo-
thetical example of a primary sludge.
It can be noted that below a concentration of about 8% solids
the sludges behave as fluids with an apparent "f" of .02 to 0.04.
Sludges with 12 to 18 per cent solids can be pumped, but with sub-
stantially higher apparent friction factors, ranging up to, say, f = 0.20
as a practical upper limit, except for extremely short distances.
These hydraulic characteristics would be measured in the laboratory
for any one sludge and the results used in evaluating alternative systems.
Alternative Transportation Systems
Pipeline. Pipeline costs are roughly proportional to the distance
transported. Double the distance and you double the cost. This is not
true with some of the alternative forms of transportation, and therefore
this important difference must be kept in mind.
Pipeline costs depend a great deal on the type and permanence of
the pipe used. In the work of Soil Enrichment Materials Corporation
55
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light-weight quick-coupled pipelines have been laid over the surface of
the ground for contracts lasting one or two years. Such lines are low in
first cost, but the entire cost of the line must be written off over the
duration of the contract of which they are a part. For example, a 4-mile
pipeline 12 inches in diameter was used for one such project. The capital
cost of the line and purnp.s was approximately $200,000 installed, It was
used to move sludge for the warm months of the year over a two-year
period. The typical rate of flow was 1.5 MGD of 5% solids sludge, for
a daily movement of 300 dry tons. With 100 operating days in each of
two years, a total of 60,000 dry tons could have been moved. (The actual
contract quantity was somewhat loss than this amount so the full opportunity
to use the pipeline did r. ;>t materialize.) The capital cost would have then
been about $3.33 per dry ton or, say, 83£ per dry ton mile. To this an
operating cost would be added for, say, a rough estimating total cost of $1
per dry ton mile. For a permanent pipeline written off over a period of
about 20 years the capital, plus operating cost is estimated to be approxi-
materly $11.30 per dry ton for a distance of 66 miles.-' This works out
to be about 17$ per dry ton mile. The figure did not vary greatly with
changes in per cent solids over a range of 4% to 7%. Table II summarizes
the analysis.
Truck Transportation. For purposes of this paper, the cost of the
truck transportation may be taken to be 6C per wet ton mile, including
loading costs. The cost per dry ton mile will then depend upon the per
cent solids handled. Trucks can be designed to handle any per cent solids,
Barge Transportation. For purposes of this paper, the cost of
barge transportation will be taken as $1.50 per wet ton for distances of
100 miles, and $2.00 per wet ton for distances of 200 miles, including
Reclamation Project", Metropolitan Sanitary District of
Greater Chicago, 1967, Harza Engineering Co., Bauer Engineering,Inc.
56
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loading costs. Again the cost per dry ton depends upon the per cent
solids which can be handled. The cost of unloading barges is very
much a function of the ingenuity of the designer, but because covered
barges would in all probability be required, it is conservative to assume
that the material would be handled in the slurry form, and (with present
practice) the per cent solids would probably not be greater than 8%, with
6% being a more commonly attained figure.
Rail Transportation. Tank cars are the most commonly used
carriers for sludge at present. Unit trains of up to 40 cars at 85 tons
each have been operated by Soil Enrichment Materials Corporation, with
24-hour turn around having been achieved as a steady practice for one-way
hauls of up to 170 miles. Under these conditions, the cost of the rail
transportation, including tanks cars is estimated to be, roughly, 1.2$ per
wet ton mile, including loading costs. For larger distances and larger
unit trains the cost would be less; for shorter distances and smaller unit
trains the cost would be more. (Note that this figure does not include
excavation of sludge from lagoons, pumping from lagoons to tank cars,
and application to land).
Again the cost per dry ton depends upon the per cent solids. Tank
cars have been used successfully with 12% solids sludge of a digested
secondary type. With primary sludges, 15% solids can be handled succe~s-
fully. The cars are equipped with agitators to permit draining of these
thick sludges from the cars in a reasonable period of time.
Alternative Application Systems
The following alternative application systems have been used for
sludge applied to agricultural land:
1. Direct dumping of filter cake from truck, followed by
spreading and plowing into the soil.
2. Direct dumping of slurry from truck, followed by plowing
into the soil.
57
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3. Flooding of prepared leveled ground from pipelines, and
later plowing of the dried sludge into the soil.
4. Irrigation of slurry using high pressure nozzles.
5. Plowing in of a slurry fed continuously through a hose
to a moving plow.
The latter system is the one presently preferred by SEMCO/ for
the following reasons:
a) It is a one stop method. There is no need to return to the
site to plow the sludge in later.
b) It allows the material to be handled entirely in closed containers.
Lack of visibility to the general public reduces aesthetic objections, even
though there may be no odor problems.
c) If there are any odor problems, even intermittent ones, this
method eliminates any adverse effects on neighbors.
I have had considerable involvement with methods 4 and 5 preceding,
and the preference for method 5 is based upon that experience for rather
large volumes of sludge to be handled on a continuous long-term basis.
I have also had experience with smaller quantities of sludge being applied
with methods 1 and 2, and have found these methods acceptable for
smaller quantities, such as less than 50,000 wet tons of sludge at one
site for one season. For the sake of illustrating the economic significance
of the various combinations of systems without getting into the benefits
of particular techniques of application, we shall use the cost figure of $20
per dry ton for each of these application methods ; this includes the unload-
ing costs from the transportation system. It is beyond the scope of this
paper to discuss the advantages and disadvantages of each of these methods,
so that this uniform cost figure will be used even though it is of course
only a hypothetical situation.
58
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Excavation from Lagoons
Tho lagooning process, though it is an economical method for
the concentration of sludges, involves the later step of reclaiming or
excavating the sludge from the lagoon. By contrast, a method for de-
watnring which can be a part of a continuous flow sheet eliminates the
expense of this excavation. For purposes of making cost comparisons
here, the lagooning step will be assumed to require the additional expense
of later excavation, and this will be taken to cost $10 per dry ton, making
a total of $15 per dry ton for this method.
Comparison of Costs
.Comparisons of the hypothetical costs of handling sludge from
a large city are given in Table I. It must be remembered that these
hypothetical illustrations are given simply for the purpose of furnishing
examples which can be discussed here. Actual costs would depend
materially on the conditions peculiar to each problem.
Alternative 1. This uses a lagooning at the site of the treat-
ment plant, foLowed by later trucking at 15% solids to a site 20 miles
distant, followed by dumping at this site and later plowing into the ground.
The transportation cost of 6£ per ton mile for a distance of 20 miles
results in a cost of $1.20 per wet ton. Dividing by 15% solids gives
the $8.00 per dry ton listed in the table for transportation.
Alt e mat iy e 2. This is comparable to the operation of Alternative 1,
except that rail haul for a distance of 100 miles is used. The material is
hauled at 15% solids, with a freight cost of $1.20 per ton for the 100 miles.
Dividing by the per cent solids gives the $8 per dry ton figure listed.
Alternative 3. Vacuum filtration is used to develop a 25%
solids condition and then the material is hauled 20 miles by truck. The
59
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transportation cost of 6$ x 20 miles $1.20 per wet ton is divided by
25% solids to obtain tho $4.80 per dry ton transportation cost listed
in the table.
Alternative 4. A portion of the sludge is concentrated by
vacuum filtration and then mixed with the unconcentrated balance of the
sludge to produce a 15% solids material. The cost is calculated for the
filtration of 55% to bo 0.55 x M6 - $8.80 per dry ton. This was rounded
off to $9, allowing a small amount for mixing with the remaining 45% of
the material which would be at about 3% solids. The resulting mixture
is then 0.55 x 0.25 I 0.45 x 0.03 - 0.1375 -f 0.0135 = 0.1510 or,
roughly, 15% solids. The transportation cost of $1.20 per wet ton divided
by the 15% solids gives the $8 per dry ton transportation cost listed.
Alternative 5. A 20-mile pipeline is used with the sludge as
produced at the plant and thickened somewhat to, say, 5% solids. This
can be pumped easily without high friction factors. The cost of the
thickening to 5% was ignored in this comparison, as it would be small.
The pipeline is written off over a period of 20 years which results in 17
-------
Discussion of Alternatives
One of the main points of this paper is to point up the great
number of possible combinations of sludge transportation and application
schemes which can be developed. This paper by no means exhausts the
possibilities, but it does suggest the significance of considering the
many possibilities which may be available.
First of all, the range of costs from $37 to $52 per dry ton is
seen to be relatively small. They are also seen to be competitive with
incineration. Unfortunately, open competition between incineration and
transportation and land application as outlined in this paper is usually
not permitted. Much of the reason for the lack of open competition is
the present policy of tho federal government to share in the capital cost
of systems, but not in the operating cost. The transportation and land
application systems are usually low in capital cost, and relatively more
expensive in operating cost than would be the incinerators as long as
the incinerators would not require repair. Once the initial incinerators
require substantial repair and maintenance, and federal funds are not
available for this purpose, then the transportation and land application
is free to compete with the alternative of incineration.
Secondly, it is significant to note the wide range in transport-
ation costs when viewed separately. Note that the most expensive is
barge transportation, a fact at odds with most commonly held opinions.
The reason is the assumption that barges would be used with 8% solids
material, which is a solids content that permits the material to be
removed from the barge as a fluid. The requirement that covered barges
be used for sludge transportation tends to work against barging of
material with a higher solids content. In the case of the railroad tank
car a much higher solids content can be handled as the contents can be
agitated with air and the tank car pressurized to force out the material
61
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as a thick slurry. It can then be diluted, if desired, for subsequent
land application.
Although all application costs were assumed to be equal, this
is of course not usually the case. For example, it is unlikely that a
barge unloading site would be adjacent to the sludge application site.
On the other hand, the trucks can usually go very close to the site of
the application. Railroads are more likely to be closer to the application
site than barges, but perhaps loss close than would trucks. Mitigating
against the use1 of trucks is the farmer's opposition to compaction of the
soil by excessive truck traffic over his tillable land. All of these factors
would be taken into account in any actual case.
Summary
One purpose of this paper is to illustrate some of the many
possible combinations of sludge transportation and application which may
be suitable to a given problem.
Another purpose is to show the competitive nature of the various
alternative systems, and to demonstrate that open and competitive bidding
which would permit a land application system to be considered as an
alternative to incineration could result in substantial savings in cost, and
also make use of the organic portion of the sludge as a resource.
The benefits to the soil from the use of sludge for enrichment
have not been discussed, as these matters are the subject of other papers
of this seminar.
One final comment to provide a perspective: A cost of $50 per
dry ton of sludge for disposal corresponds to less than $2 per capita per
year, as the sludge from roughly 30 persons amounts to about 1 dry ton
per year. Possible differences in cost arising from alternative systems are
even smaller. It appears that considerations other than cost should determine
the best use of this resource rich in organic material.
62
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BAUER
ENGINEERING
INC.
PROJECT NAME.
SUBJECT
•Y-
_DATE_
_CM'KD_ DATE—
•MEET OF
I
O.IO
63
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TABLE 1
COMPARISON OF ALTERNATIVE METHODS FOR HANDLING SECONDARY SLUDGE
FROM A LARGE CITY.
DOLLARS PER DRY TON
System
Description
1 . Lagooning and later
excavation, then
trucking to site 20
miles distant, where
it is dumped and
later plowed into the
soil at 15% solids
2. Lagooning and later
excavation, then 100
miles rail haul to site
at 15% solids, then
dilution and plowing
into soil at 10% solids
3 . Vacuum filtration to
25% solids, then truck
haul to site 20 miles
distant, where it is
dumped and later plowed
into the soil at 25%
solids
4. Vacuum filtration of 55%
to 25% solids, then mix-
ing with remaining 45%
of sludge at 3%, 100-mile
rail transportation at 15%
solids , then dilution and
plowing in at 10% solids
5 . Pipelining for 20 years
at 5% solids for 20 miles
then lagoomng, later
excavation and plow
application at 10% solids
Dewatering
Cost
$15
15
16
9
15
Transportation
Cost
$8.00
8.00
4.80
8.00
3.40
Application
Cost
$20.00
20.00
20.00
20.00
20,00
Total
Cost
$43.00
43.00
40.80
37.00
38.40
64
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TABLE 1 (cont'd)
COMPARISON OF ALTERNATIVE METHODS FOR HANDLING SECONDARY SLUDGE
FROM A LARGE CITY.
DOLLARS PER DRY TON
System
Description
6. Same as 5, except
for 100 miles
7. 100-mile barging of
8.0% material after
vacuum filtration of
20% of total and mix-
ing with remaing 80%,
followed by application
to land
Dewatering
Cost
$15
3.50
Transportation
Cost
$17.00
18.75
Application
Cost
$20.00
20.00
Total
Cost
$52.00
42.25
65
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TABLE II
CALCULATION OF PIPELINE TRANSPORTATION COSTS
(Based on Table G-l, 1967 "Land Reclamation Project"
report by Harza Engineering Co. and Bauer Engineering,
Inc. to Metropolitan Sanitary District of Greater Chicago.)
Item
Pipeline length
Capital Cost (67)
Capital Cost (7 3)
Annual Capital
Cost, 6% ,20 yrs
Annual Operat-
ing Cost, energy
Annual Operat-
ing Cost, other
Total Annual
Cost
Dry tons/year
$/dry ton
$/dry ton
mile
Site 1
65 miles
$20.7 million
41.4
3.73 "
.08 "
0.52 "
4.33 "
365,000
$12.10
0.187
Site 2
57 miles
$18.5 million
37.0
3.33 "
0.08 "
0.52 "
3.93 "
365,000
$10.80
0. 189
Site 3
66 miles
$19.7 million
39.4
3.53
0.08
0.52
4.13
365,000
$11.30
0.172
Site 4
35 miles
$12.7 million
25.4 "
2.29 "
.06 "
.52 "
2.87 "
365,000
$ 7.90
0.225
66
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8CME CONSTRAINTS OP SPREADING SEWAGE SLUDGE ON CROPLAND *
by
G. K. Dotson **
Disposing of the solids removed from sewage has long been a difficult
and often frustrating part of sewage treatment. Developing better methods
of treating sludge and finding environmentally safe places to dispose of it
are responsibilities of the National Environmental Research Center of
Cincinnati, Ohio. The amount of sludge to be disposed of is increasing
rapidly as cities adopt more sophisticated treatment systems. Utilizing
a potential waste, sewage sludge, to fertilize and Improve soils is an
appealing alternative to other disposal methods.
The how sludge is applied to land is determined by the why it's applied.
When the objective Is disposal only, the protection of the soil is unimportant
and high application rates are acceptable. Preventing water and air pollution
and avoiding nuisance conditions are the main precautions. When the objective
is reclamation of unproductive soils, greater leeway may be permitted in
regard to application rates and accumulations. When the principal objective
is the addition of fertilizer, water, and organic matter to cropland, the
operating options are more limited. Protecting the productivity of the
soil and the crops is necessary. The constraints discussed in this paper,
unless otherwise stated, are those that apply to the use of sludge for crop
production and soil improvement.
Composition
The composition of sewage sludge is variable. A 2-inch application of
* Presented at Rutgers University Symposium on Land Disposal of Municipal
. Effluents and Sludges, March 12-13, 1973.
** Research Soil Scientist, Ultimate Disposal Research Program, Advanced
.. Waste Treatment Research Laboratory, National Environmental Research
Center, EPA, Cincinnati, Ohio.
67
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Chicago sludge supplies 200 to 350 pounds of ammonium nitrogen and about
the same amount of organic nitrogen; 250 to ^50 pounds of phosphorus, of
which about 80 percent is organic; and about 60 pounds of potassium per acre
(Hinesly et al., 19T2a). Two inches of liquid sludge, with a solids content
of 3 percent, contains about 7 tons of solids.
Nitrogen
And it's the nitrogen component of sludge that usually first limits
its rate of application. The nitrogen content of sludge varies from
about 2 to 6 percent according to the composition of the sewage and the
treatment the sewage and sludge received.
Ewing and Dick (1970) in their study of sludge disposal on land
presented a hypothetical model to illustrate that 1 inch of liquid sludge
would add 3**0 pounds of nitrogen to an acre of soil. Of this, 150 pounds
would be removed by the crop; 20 percent would be evolved; mineralization
would balance the added organic nitrogen; and the net immobilisation
would be zero. The model indicated that only a little more than 1/2 inch
of digested sludge per year could be applied to the acre without contributing
nitrogen to leachates. But Hinesly (l9T2a) suggested that about 10 to 15
tons, or about 2 to 3 inches, of an average sludge might be required to
meet the nitrogen needs of a nonleguminous crop. Mixing up to 160 tons
of sludge solids per acre of soil with clay subsoils did not cause nitrates
to leach into ground water at Beltsville, Maryland (Menzies, 1972).
The pathways of nitrogen in soils and the degree of hazard it presents
to ground water are difficult to predict. Many processes effecting changes
in the form of nitrogen may occur concurrently in soils, and the rate at
which they take place is determined largely by soil type and climate.
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Mineralisation, the conversion of organic nitrogen to ammonia,
proceeds at variable rates depending on climatic and soil factors
and the nature of the organic matter. Soils in the eastern part of
the country naturally average about 3,000 pounds of nitrogen per
acre, and about 2 percent of this is mineralized annually. Sludge
nitrogen is mineralized at about 5 percent per year.
Digestion converts part of the organic nitrogen in raw sludge
to ammonium. Eving reported that Chicago sludge contains about
1,500 milligrams of nitrogen per liter, about 1+0 to 50 percent of
which is ammonium. Some ammonium may be fixed by organic matter and
silicate clays and be protected from biological attack. Volatiliza-
tion of ammonia may be substantial from soils with high pi.
Denitrification, the transformation of nitrate nitrogen to
nitrogen gas, takes place where free oxygen is absent or deficient
and other conditions, Including a supply of carbon, are favorable
for biological activity. The nitrification rate is relatively fast
in aerobic soils with favorable temperature.
Microbes utilize part of the available nitrogen In soils to
synthesize new cells.
Plant uptake of nitrogen varies greatly, but may be 150 to
25O pounds per acre for a corn crop and more for other grasses.
The amount of nitrogen removed in runoff varies with precipita-
tion patterns and farming practices.
Obviously, only general guidelines are possible when determining the
rate that sludge can be applied to cropland without nitrate pollution of
ground water. Soil type, geology, climate, crops, and farm management are
69
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Important factors In determining the fate of nitrogen added in sludge.
Soil management techniques may be used to prevent nitrate pollution of
surface or ground water because of sludge applications. Perched water
tables may be used to cause devitrification. Leachates and runoff water
may be caught and treated or reused for irrigation. Soil conservation
practices that prevent soil erosion and retard runoff of surface water
should be applied where sludge is applied to crops.
Metals
There is much concern about the increase of metals in the environment,
particularly in the food chain. Sludge applied to soil is only one source
of metals and other trace elements. Other significant sources of such
soil pollution include airborne emissions from factories, automobiles, and
smelters; and liquid and solid waste discharges from industries, municipali-
ties, and natural runoff Including pesticides, fertilizers, mine wastes,
fly ash, and animal manure. The potentially toxic metal content of Kludge
varies greatly. Industrial cities of all sizes tend to produce sludges
with high concentrations of metals. Although sludge of domestic origin
is lower in metals than Industrial sludge, concentrations of cine and copper
la excess of those found in soil are present.
Some metals and other trace elements are essential nutrients for plant
growth. Although essential in small quantities, they are toxic at
relatively low levels to some crops. Berrow and Webber (19T2) analyzed
samples from U2 municipal plants treating waste from both small residential
communities and large industrial cities. They found silver, bismuth, copper,
lead, tin, and zinc were consistently moee concentrated in sewage sludge than
in agricultural soils. In a few sludges, boron, cobalt, molybdenum, chromium,
70
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and nictel were also higher. Zinc, copper, and nickel are most likely to
build, to toxic levels as a result of sludge spreading. The British Ministry
of Agriculture, Fisheries, and Food suggested that nickel was eight times
as toxic to plants as zinc, and that copper was twice as toxic to crops.
They recommended that the total of capper, zinc, and nickel added to
British soils should not exceed the equivalent of 500 pounds of zinc per
acre. Other metals that may be present in sludge in excess include
chromium, cadmium, lead, and mercury. Although sludge-borne boron is
soluble and leaches from soils in humid areas, excessive concentrations
of boron in the sludge or dry weather that would halt leaching could cause
temporary boron toxicity to result from sludge spreading. Salts are also
soluble and could be harmful under the Bane conditions as boron. Rohde
(1962) attributed toxicity on sewage farms near Paris and Berlin to copper
and zinc accumulations.
Opinions differ widely regarding the hazard of trace element toxicity
caused when sewage sludge is used as a fertilizer and soil conditioner.
The University of Illinois has applied 150 tons of digested sludge solids
per acre to corn plots without causing toxicity. The metals added greatly
exceed the suggested limit for British soils. The corn yield from these
sludge-treated plots equalled that from the fertilized check plot and
neither corn nor forage crops have shown any toxicity symptoms. They have
not accumulated substances to lower the quality of the crop for livestock feed.
Anderson (1969) from the Agricultural College of Sweden suggested that the
rate of application of sewage sludge to fields should be based on the content
of toxic components of the sludge. Others have expressed doubt that the
prudent use of sewage sludge on farm laud will cause toxicity in the soil.
71
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Le Riche (1968) analyzed soils and crops from a market garden experiment
In Woburn, Knglaivl, where from 19^2 to 1961, 568 tons of sludge solids were
applied. Although there was some Increase In metals uptake by toe
vegetables, crop yields were unaffected.
There Is a dearth of Information concerning the fate of heavy metals
applied to soils. Most of the reports about toxicity have not recorded
the concentrations of metals In the soils and plants* Many combinations
of soil types, plant species and varieties, and climate were involved.
Only soluble trace elements, those available to the plants, cause
toxicity. Several soil characteristics Interact to determine the avail-
ability of trace elements to plants. Copper, nickel, and tine can be
cnelated by organic matter, adsorbed on silicate clays, or precipitated
near the soil surface. They are low in solubility and therefore do not
leach to any appreciable degree. Oxides of iron and manganese adsorb
metals, so maintaining oxidizing conditions in the soil tends to keep
metals unavailable to plants. Neutral or slightly «.iir«Hnft pH helps to
keep metals immobilized.
There are other reasons why permissible levels of trace elements added
to soil* are difficult to determine. Not only do plant species vary widely
in uptake and tolerance of metals, but varieties of a species differ.
Much of the information concerning plant response to metals has been
obtained from greenhouse pot culture. Indications of the transformations
of metals in soils can be gained that way, but only by studying the effects
of prolonged applications of sludge to sails In the field can the tolerable
72
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levels of trace elements be determined. The EPA-supported research project
performed by the University of Illinois for Chicago is supplying some
answers.
Much of the toxicity studies have involved only an excess of one or
two elements. The interactions of many trace elements applied in sewage
sludge are not completely understood. Greenhouse and other studies in
Illinois have shown that there are both synergistic and antagonistic
Interactions between metals that affect the uptake and translocation within
plants (Hlnesly, 1972a).
The Information nov available on metals is inadequate to set specifi:
guidelines for applying sludge to soil. Long-term field studies are needed for
various combinations of crops, soil types, and climate.
Fending the establishment of guidelines for permissible additions of
trace elements in sludge, some precautions should be observed with high
rates of sludge application or with prolonged applications at lover rates.
Regular testing of crops and soils should forewarn of toxic accumulations.
Liming and maintaining oxidizing conditions and a high level of organic
matter in the soil will help to keep metals immobilized.
Pathogens
Although no records exist of diseases having been caused by using
digested sludge as a soil conditioner or fertilizer, this is still a
concern of many people. A 1950 literature review by Rudolfs et al.
pertained to the occurrence and survival of pathogenic organisms. The
summaries of results of more than 100 experiments shoved that under
variable conditions of climate, soils, and plants, the viability of patho-
T
genie organisms in soil may last for only a few hours or as long as several
73
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months. Among the most important factors influencing the survival time of
intestinal pathogenic organisms were the type of organism, soil type,
moisture, temperature, pH, and the presence of antagonistic organisms in
the soil. A study (JCenner et al., 1971) at the National Environmental
Research Center in Cincinnati determined that fecal coliforms survived for
at least 21 weeks after a single sludge application in the spring. The
bacterial pathogens studied, Pseudomonas aeruginosj. and SalmonsIIA Sp.,
were less hardy under the study conditions. Under winter conditions in
Cincinnati, the indicators and pathogens lasted longer.
Intestinal bacterial pathogens are either destroyed or their numbers
greatly diminished by heated anaerobic digestion for 14 days (Hinesly,
1972a). The manner in which most digesters are operated does not ensure
that «-T> sludge removed will have been in the digesters long enough for
pathogens to be killed. Some bacteria, viruses, and parasites may survive
digestion and remain viable in the digested sludge. The degree of disease
hazard involved in spreading undisinfected sludge varies with the .Land use.
Pathogens or parasites on soils where people come into direct contact with
the soil would present more of a hazard than on soils devoted to producing
farm crops. Low growing fruits and vegetables can become contaminated
with sludge-borne pathogens. Undisinfected sludge placed on shallow soils
underlaid by porous material or on soils that crack when dry may cause
pathogens to reach ground water. Good soil and water conservation practices
are needed to prevent erosion from sloping land. Percolation of water
through 5 feet of unsaturated soil should remove pathogenic organisms.
74
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If disinfection is needed, pathogens in sludge can be destroyed
through:
(1) storing for long periods;
(2) pasteurizing at 70° C for 30 minutes;
(3) «"M1"g lime to raise pi to 11.5 or higher and maintaining the pH
abore 11.0 for 2 hours or more;
(k) using chlorine to stabilize and disinfect sludge; or
(5) using other chemicals. (Dotson et al., 1973)
Long storage of sewage has been suggested as one of the simplest methods
of racing pathogenic organisms (Berg, 1966). Storing sludge for 30 days
reduced fecal conforms by 99^9 percent (Hinesly, 1972a), although some
parasites probably persist much longer when sludge is stored in lagoons.
Most large municipalities that dispose of sludge by spreading on land store
it la lagoons—this provides the flexibility needed at times when sludge
cannot be spread.
Sludge spread on pastures during the grazing season in Germany and
Switzerland 10 pasteurized. Maintaining a temperature of 70° C for 25 to 30
minutes frf11* pathogens, viruses, cysts, worm eggs, and obcytes (Liebman, 1967).
Direct steam injection avoids fouling and sealing of heat exchangers. Heat
recovery is \m^cffn<^ffi^*l for small plants.
Pasteurizing digested sludge has been studied at the national Environmental
Research Center In Cincinnati. Pathogens were killed when steam was injected
into a tank truck raising the temperature of the sludge to 75° C and maintaining
it for one hour. The sludge killed bluegrass when applied to the lawn at a
75
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temperature greater than about 60° C. The cost for pasteurizing four
5,000-gallon truckloads of sludge per day was estimated at $12.50 or less
per ton of solids (Dotson et al,, 1972)•
In 1967, Triebel reported the cost of pasteurization in German marks
(Dotson et al., 1978). The dollar cost, with four marks equal to one
dollar, is estimated as:
Tons of digested sludge Cost per ton of sludge
pasteurized annually solids, 1967
780 $8.60
1560 6.te
5000 1.85
Lining digested or physical-chemical sludges to pH 11.5 killed pathogens
In batch tests at the EPA pilot plant at Lebanon, Ohio, with costs estimated
at about $10 per ton of solids (Farrell et al., 1972).
Application of Sewage Sludge
Insufficient stabilization may limit the places that sludge can be
applied and the rate of application. High oxygen demand increases the
hazard of odors and temporary toxicity either in storage or on land. When
the volatile solids content of rav sludge is reduced by less than 50 percent,
the sludge is incompletely stabilized and could cause odor and fly problems.
Applying veil-stabilized sludge in thin layers avoids nuisance and toxicity
problems associated with thick applications.
Digested sludge has been shown to be toxic to germinating corn
(Hinesly et al., 1972a). Ammonia has been identified as one of the toxins,
but not the only one. Anaerobic decomposition of organic waste also produces
76
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volatile organics toxic to plant roots and seedlings. Aging digested
sludge or delaying applications for about 3 weeks after planting of the
crop should avoid the problem.
Many other factors might limit the vay and the rate where sludge can
be spread. Soil properties, legal restraints, and sludge properties may
serve as constraints on sludge spreading. Public resistance to spreading
municipal wastes in rural communities has been general. Many instances of
apparently mutually advantageous utilisation of municipal wastes to Improve
rural land have been rejected by local residents because they were not
convinced it was beneficial to them. Spreading sludge to taprove soils
and crops for the benefit of the local community according to a plan
developed and publicized with local residents is much more likely to be
received with enthusiasm than one that is planned and unilaterally
Implemented by city officials.
77
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RtamadBHCES
Anderson, A., 1969. "Some News Regarding the Use of Municipal Wastes Within
Farming," Girundfoerbaettring, 22, ^2-1*3.
Anon., 1972. "Permissible Levels of Toxic Metals in Sewage Used on Agri-
cultural Land," Advisory Paper Ho. 10, Ministry of Agriculture,
Fisheries, and Food, London, England.
Berg, G., 1966. "Tirus Transmission by the Water Vehiole. II. Virus Removal
by Sevage Treatment Procedures," Health Library Science, 2(2), 90.
Borrow, M. L., and Webber, J., 1972. "Trace Elements in Sevage Sludges,"
J. Sci. Food Agrl., 2£, 93-100.
Dotson, G. K., Dean, R. B., and Stern, G., 1973. "The Cost of Dewatering
and Disposing of Sludge on Land." Presented to 6 5th Meeting of the
AIChE, New Tork, Nov. 26-30, 1972. To be published in "Water-1972" (AIChE),
Eving, B. B., and Bick, R. I., 1970. "Disposal of Sludge on Land." In "Water
Quality Improvement by Physical and Chemical Processes," Univ. of Texas
Press, Austin. E. F. Gloyna and W. W. Eckenfelder, Jr., editors.
Farrell, J. B., Smith, J. E., Hathaway, S. W., and Dean, R. B., 1972.
"Lime Stabilization of Chemical-Primary Sludges at 1.15 MBD." Pres.
to 45th Annual Conf., Water Poll. Control Federation, Atlanta, Georgia,
Oct. 8-13, 1972. To be published in JWPCF.
Hlnesly, T. D., Braids, 0. C., Molina, J. A. E., Dick, R. I., Jones, R. L.,
Meyer, R. C., and Welch, L. T., 1972a. "Agricultural Benefits and
Environmental Changes Resulting from the Use of Digested Sevage Sludge
on Field Crops." Annual Report, Untr. of Illinois and City of Chicago,
EPA Grant BO l-UI-00080, unpublished.
Hlnesly, T. D«, Jones, R. L., and Ziegler, E. L., 1972b. "Effects on Corn
by Applications of Heated Anaerobically Digested Sludge," Compost Science,
» 26-30, July-Aug. 1972.
Kemier, B. A., Dotson, G. K., and Smith, J. E., Jr., 1971* "Simultaneous
Quantitation of Salmonella Species and Pseudomonas Aeroginoaa,"
EPA-NERC-Cinclnnati, internal report.
Le Riche, H. H., 1968. "Metal Contamination of Soil in the Wobum Market--
Garden Experiment Resulting from the Application of Sevage Sludge,"
J. Agri. Sci. Camb., Jl, 205-208.
Liebnan, H., 1967. "Hygienic Requirements for Sludge Pasteurization and Its
Control in Practice," International Research Group on Refuse Disposal
(IRORD), Info. Bull. Nos. 21-31, Aug. 1964-Dec. 1967, pp. 325-330.
78
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Menzies, J. D., 1972. Personal communication.
Rohde, 0*, 1962. "The Effects of Trace Elements on the Exhaustion of Sewage-
Irrigated Land," Inst. of Sewage Purif. J.t 581-585.
Rudolfs, W., Falk, L. L., and Ragotzke, R. A., 1950. "Literature Review on the
Occurrence and Survival of Enteric, Pathogenic, and Relative Organisms in
Soil, Water, Sewage, and Sludges, and on Tegetation. I. Bacterial aad Tlrus
Diseases," Sewage and Industrial Wastes, 126l-128l (Oct. 1950)
79
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METHODS OF LIQUID FERTILIZER APPLICATION
By
Bart T. Lynam, General Superintendent
Robert 0. Carlson, Principal Agricultural Engineer
METROPOLITAN SANITARY DISTRICT OF GREATER CHICAGO
Presented to the
Symposium on "Land Disposal of
Municipal Effluents and Sludges"
Rutgers University
New Brunswick, New Jersey
February 12 and 13, 1973
Preceding page blank
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METHODS OF LIQUID FERTILIZER APPLICATION
Bart T. Lynam, General Superintendent
Robert 0. Carlson, Principal Agricultural Engineer
The Metropolitan Sanitary District of Greater Chicago (MSDGC)
applies anaerbically digested sewage solids (liquid fertilizer) to
strip mined land to restore its organic matter content, and to
supply plant nutrients for crop production. The methods of application
used are: a tank truck equipped with a manifold across the rear end;
various irrigation systems; and an incorporation method that is
being developed. This presentation will describe each of the systems
used.
Tank Trucks
The manifold is an eight foot pipe, eight inches in diameter,
mounted on the rear of the tank truck and connected to the tank.
Opening a valve allows the fertilizer to flow, by gravity, from the
tank to the manifold. The manifold has a series of holes along the
bottom to allow the fertilizer to flow onto the ground. The forward
speed of the truck controls the rate of application.
Flood Irrigation
A simple flood irrigation method has been used to apply the
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liquid fertilizer to a leveled sanitary landfill. This method
achieved some degree of success. While the liquid portion flowed
across the field the solids had a tendency to settle out near the
inlet, resulting in uneven application of solids across the field.
Ridge and Furrow
A ridge and furrow system has been used. Gated irrigation
pipe conveys the fertilizer to the field where it flows into furrows
formed by a lister. A row crop is planted on the ridges and the
furrows distribute the fertilizer between the rows. This method
requires a great deal of land preparation.
Wheel Roll
SEMCO (Soil Enrichment Materials Corporation), a firm with
expertise in liquid fertilizer application to farmland, applied
liquid fertilizer with an irrigation system called a "wheel roll".
Eight inch diameter pipe was used to convey the liquid fertilizer
one-half of a mile across a field. Spray nozzles spaced along the
top of the field piping were used to apply the liquid fertilizer.
The pipe also serves as the axle for the wheels which move the
irrigation system across the field. To move the system the flow
is shut off which causes the pressure to drop. This pressure drop
opens valves on the underside of the pipe allowing the water to
drain out. When the pipe is emptied the whole system is moved across
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the field to a new position.
When using this system the drain valves often plugged, thus
the entire half mile length of pipe remained full of liquid fertilizer,
Attempts to move the system with the pipe full resulted in twisted
pipe or broken wheels - making the system inoperable.
Center Pivot
Some companies which manufacture center pivot irrigation systems
have shown considerable interest in altering their systems to apply
liquid fertilizer. The problem with the center pivot irrigation
systems is that the nozzles nearest the point of pivot must be of
a small diameter (1/16 to 3/16 of an inch) since they have only a
small area to irrigate. The nozzles get larger as they become
progressively further from the point of pivot. At the outer end
the nozzles are three fourths of an inch in diameter or larger.
Experience has shown that to apply liquid fertilizer the nozzles
must be at least one inch in diameter and the nozzle pressure about
50 psi.
Traveling Sprinkler
The most successful sprinkler system used to date is the
traveling sprinkler. A single nozzle mounted on a carriage travels
across the field applying a swath about 300 feet wide. A flexible
hose, 660 feet long and five inches in diameter, is pulled along
with the traveling sprinkler and connects the sprinkler to the
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irrigation piping. Nozzles that are 1.5 to 1.9 inches in diameter
with a nozzle pressure of 50 to 80 psi have been used satisfactorily.
To date this system has caused no plugging and will apply 400 to
700 gpm. Figure 1 shows this irrigation system applying liquid
fertilizer.
Incorporation System
The Sanitary District has developed equipment which incorporates
the liquid fertilizer into the ground. A manifold mounted on a heavy
duty disc harrow or two-way plow delivers liquid fertilizer to the
inside of each disc blade or mold board which then covers the
liquid fertilizer as the unit moves forward. The source of supply
is the same hose that supplies the traveling sprinkler irrigation
system described above. Figure 2 shows a disc equipped to apply
liquid fertilizer.
Rates of Application
The speed of the applicator across the field governs the rate
of application. For example, if the flow rate is 800 gpm, it would
take 34 minutes to apply one acre inch of liquid fertilizer. If the
system applies the fertilizer to a swath 300 feet wide, the unit would
have to travel 145 feet during 34 minutes to apply to one acre.
Thus the unit travels 4.25 feet per minute. If the solids content
is 5% this acre inch contains 11,300 pounds of solids. Weather and
soil conditions dictate the allowable rate of application, within
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the limits set by the Illinois Environmental Protection Agency. These
limits are 75 dry tons per acre per year on strip mined soils and
25 dry tons per acre per year on unstriped soils.
The District intends to apply the equivalent of 75 dry tons
of liquid fertilizer the first year, 60 the second, 54 the third,
and 30 dry tons the fourth year. These application rates apply
only to strip mined land, which is devoid of organic matter. This
totals 219 tons per acre during the first four years. These
application rates were established after several years of research
by the University of Illinois, College of Agriculture.
Above average precipitation during the last half of 1972
prevented application of more than a token amount of liquid
fertilizer. The 75 dry tons will require the application of 13
acre inches while the 60, 54, and 30 dry ton applications will
require 11, 10, and 5 acre inches respectively. Because the
higher application rates will be difficult to attain in one year,
application may apply less than 75 dry tons the first year but
more than 30 dry tons the fourth year. Considerable effort is
being directed towards increasing the solids content of the
irrigant, since this is the primarly limiting factor with
irrigation systems.
Transportation and Application
The District transports liquid fertilizer from Chicago to
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Fulton County by barge. The distance is 180 miles. At a dock
just west of Liverpool, Illinois, pumps remove the fertilizer
from the barges and transport it by pipeline to a pumping station
about 1000 feet from the river. This pumping station, with three
pumps powered by 300 HP electric motors, pumps the fertilizer through
a 20 inch underground pipeline 11 miles to the holding basins on
Sanitary District property.
Figure 3 shows diagrammatically the distribution and application
system. A dredge floating in the basin removes the liquid fertilizer
from the basin and pumps it to a holding tank adjacent to a pumping
station. The pumping station conveys the fertilizer to the fields
through 10 inch spiral welded steel pipe laid on the soil surface.
Eight inch aluminum irrigation pipe conveys the fertilizer from the
steel pipe to a five inch rubber hose. The hose is 660 feet long
and is connected to the application unit.
The systems for applying liquid fertilizer to land are still
in their infancy. The District continues its efforts to develop
these systems to increase the efficiency of liquid fertilizer
application.
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This
Figure 1. Irrigation System used in Fulton County to Apply Liquid
Fertilizer to Strip-mined Land.
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5C*-S*M
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
Figure 2. The Incorporation System Applying Liquid Fertilizer to Strip-Mined Land in Fulton
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A BASIN
B FLOATING DREDGE
C FLDATING PIPELINE
D 57tOOO GAL. TANK
E PUMPING STATION
F IO"DIA. SPIRAL STEEL PIPE,
ON SOIL SURFACE
G ALUMINUM IRRIGATION PIPE,
8*DIA.
H 5"DIA. RUBBER HOSE, 66O FT.
LONG
I NOZZLE MOUNTED, FOUR WHEEL
CARRIAGE
FIGURE 3 Diagram of the
jjiay i aiu UJ. L.IIC ^/ —»—*-
Distribution and Application System for Liquid Fertilizer
Application.
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BIBLIOGRAPHY
McMillan, Hugh, Assistant Chief Engineer, and Carlson,
Robert, Principal Agricultural Engineer, Metropolitan
Sanitary District of Greater Chicago. Using Wastewater
Solids to Reclaim Strip-Mined Land. Presented at AIME
Annual Meeting, Chicago, Illinois, February 25, 1973.
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EQUIPMENT FOR INCORPORATING SEWAGE SLUDGE AND ANIMAL MANURES
INTO THE SOIL
by
Charles H. Reed*
For centuries, man has applied animal manures and
human sewage to the soil to improve crop production. The
principal technique was to spread them on the land and then
work them into the soil.
With the expanding population, depletion of our
natural resources, and intolerable pollution of the atmosphere
and hydrosphere (1), there is an urgent need for techniques to
recycle biodegradable wast.es INTO the upper horizon of the soil
where they are degraded and utilized, resulting in a beneficial
effect upon the environment. Bohn and Cauthorn (2) state, "In
summary, compared to air and water, the soil has a vastly
greater potential for waste disposal and transformation....and
it has the capacity to absorb far more material than it can
produce or than is added to it."
The incorporation of wastes directly into the soil is
superior to surface spreading because there are no odors, no
opportunity for flies or other pests to feed or breed, no runoff
or surface erosion of wastes, and the wastes are placed in the
best possible media for immediate degradation to plant nutrients
and utilization by plants. These techniques conform to the
concept of land treatment as defined by Stevens et al.(3):
* Professor of Agricultural Engineering, Department of Biological
and Agricultural Engineering, Rutgers University, New Brunswick,
New Jersey, March 1973. Journal Series paper. Paper presented
at Conference on Land Disposal of Municipal Effluents and
Sludges. March 12-13, 1973. College of Agriculture and Environ-
mental Sciences, Rutgers University, New Brunswick, New Jersey.
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Land treatment is any of several methods of
waste water treatment and sludge application "which
consider the qualities o± land, waste water and
sludge in the design of facilities. Land treatment
conveys the reciprocal, beneficial relationship
between the land and the waste. Most such facili-
ties are designed to produce valuable end products,
such as green crops and pure effluent as a result
of the treatment processes.
"Land treatment differs from land disposal,
a term used to describe any method which applies
sewage, raw or treated, to the earth; and land
application, a term used by EPA to describe all
methods of waste water disposal associated with
the ground, i.e., sewage farms, land treatment,
septic systems, and underground disposal."
The design of an effective land treatment system and
the selection of appropriate equipment necessitates the con-
sideration of many factors, some of which are outlined below:
Wastes to be incorporated into soil.
Kind and previous treatments.
Physical and chemical properties, i.e.,
% solids (wet basis).
Rate of production (daily, weekly).
Storage available or required.
Transportation.
Distance to sites.
Mode of
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Site characteristics or limitations.
Acreage.
Topography.
Existing vegetation.
Soil characteristics.
Ground water (Depth, quality).
Location of human habitation.
Distance.
Prevailing wind.
Climatic limitations.
Temperature. Duration of frozen soil.
Rainfall. Seasonal, normal, and extreme
variations.
End product desired. Crops to be raised,
use of land, etc.
Irrigation of sewage sludge and effluent is receiving
considerable attention at this time (4,5). Only thin slurries
with low solids content can be irrigated. Because of the high
water content (more than 95% as it comes from the digesters)
conveyance to disposal sites by pipeline may be the only practical-
transportation system. Storage structures at the sites will be
required during periods of sub-freezing temperatures, frozen
impervious soil, saturated soil, and other periods of shut down.
Unless thoroughly digested, surface applications of sewage
sludge may generate odors and attract flies. Any surface appli-
cations are susceptible to surface runoff. There is a possi-
bility of soil-clogging and waterlogging when sewage sludge is
irrigated (3,6). Also, there may be damage to foliage when
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large quantities of sludge are repeatedly sprinkled on plants.
There will be large power requirements. The aerosol effect
may limit high-pressure irrigation on some sites.
Irrigation of effluent containing only dissolved
solids can be managed without many of tha above disadvantages
of sewage sludge, and may be considered for irrigation of
crops when needed or ground water recharge. The limiting factor
usually is the amount of water which can be added to the soil
at different seasons of the year; i.e., ice buildup, or
saturated soil.
Composting is an ancient technique of recycling bio-
degradable wastes. Modern techniques and equipment have been
developed to compost balanced mixtures of biodegradable wastes;
including sewage sludge, animal manure, and solid wastes. See
Compost Science, Vol. 13, No. 3, May-June 1972, for information
on General Motors' Terex-Cobey Composter. These techniques are
relatively expensive and may generate some localized odor. Well-
cured compost can be spread on the land without attracting flies,
is not as susceptible to surface runoff as in non-composted
waste, and is an excellent soil conditioner. An outstanding ad-
vantage of compost is that it can be readily stored in piles at
low cost without nuisance until an appropriate time for applica-
tion in the soil.
Land spreading is the most ancient method of utilizing
both human and animal excreta. When plowed or disked immediately
after application it is an effective method of incorporating
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them into the soil. When large quantities are involved, this
may be the most economical, but if not properly treated, it
will not be the most sanitary technique.
The ridge-and-furrow technique might be considered
a surface method of application unless covered immediately.
•The furrows can be made on-the-contour or slightly sloping to
permit the water to filter into the soil. Ridge-and-furrows
on the contour have been used experimentally at the New Jersey
Agricultural Experiment Station as a low-cost winter storage.
Aerobic conditions should be maintained in and at the bottom
of the furrow.
Equipment has been developed which will incorporate
wastes directly into the soil, either in one or two operations
by Sub-Sod-Injection or Plow-Furrow-Cover.
Sub-Sod-Injection (SSI) equipment is available which
will inject any slurries that will flow by gravity or under
pressure through a 6-inch diameter hose 2 ft. long. Animal
manures with up to 20% solids and sewage sludge with up to 10%
solids can be injected by gravity into the soil at the rate of
400 gallons per minute in a band up to 2 inches thick and
28 inches wide and from 6 to 8 inches beneath the surface without
turning over the soil. The injector has a standard Category 2
three-point hitch with a spring-trip release for passing over
subsurface objects. It is comparable to a two-bottom plow in
weight and durability. This equipment is not yet available
commercially, but can be assembled from existing components.
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The Plow-Furrow-Cover (PFC) method is the most
adaptable of any of the previously mentioned techniques. Equip-
ment is available, or can be assembled from manufactured com-
ponents, to incorporate directly INTO the upper 8 inches of the
soil up to 300 tons per acre of biodegradable wastes, ranging
from thin slurries (septic tank pumpouts) to semisolids (sewage
cake). PFC leaves the soil plowed and ready for disking and
seeding. Two types of equipment will be described for PFC:
one for 25% solids or less, and the other for greater than 25%
solids.
One of the two recently developed pieces of equipment
were assembled by Agway, Inc., of Syracuse, New York. The
first one was used at the University of Connecticut in a re-
search demonstration project to study the effect of incorporat-
ing septic tank pumpouts into the soil. In this project more
than 100,000 gallons of slurry were incorporated into the soil
in 2 months. The capacity of the tank is 800 gallons. A 9-inch
auger with ample hydraulic power from an auxiliary hydraulic
pump on the tractor, and 12-inch as well as 6-inch valve open-
ings will unload much heavier solids than would the previous
prototypes. The highest limit of solids content which it will
unload has not yet been determined. This equipment will not
unload low-moisture sewage cake, semisolid animal manures with
bedding, or caked poultry manure reinforced with feathers. A
gooseneck tongue is built permanently into the tank to provide
easy maneuverability of either a 16-inch single-bottom mold-
board plow or a sub-sod-injector which are mounted on the
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three-point hitch of the tractor.
A second unit, constructed in 1973, is identical,
except that it has a capacity of 1,500 gallons, a 9-inch
ribbon auger, and a slurry spreader on the rear. The augers,
valves and spreader are powered by the hydraulic system on
the tractor.
To plow-furrow-cover, a 16-inch single-bottom mold-
board plow is mounted on the 3-point hitch of a standard farm
tractor. A slurry with up to 25% solids can be deposited into
a 6-to-8-inch-deep plowed furrow. Immediately after deposition,
and in the same operation, the plow covers the waste and opens
the next furrow. With properly adjusted equipment, 1% to 2
inches of slurry can be completely covered. This is approxi-
mately 170 to 225 tons of slurry per acre. A well-formed furrow,
16 inches wide, 7 to 8 inches deep and 400 feet long with
1% inches of slurry, contains 500 gallons, or approximately
2 tons. PFC leaves the soil well-plowed and ready for disking
and seeding. The equipment has been designed to operate at
3 mph and unload up to 200 gallons of slurry per minute. The
axle of the trailer is adjustable so that the trailer is offset,
permitting the right rear trailer wheel to travel in the newly
formed clean furrow.
A combination transport and field unit was assembled.
It consists of a tank on a four-wheel-drive, 1^ ton truck chassis
with flotation tires, and is equipped with a hydraulic pump,
controls, and a Category 2 3-point-hitch. The tank has a
capacity of 500 gallons. With a 12-inch ribbon auger in the
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bottom of the tank and a 12-inch diameter valve, semisolid
animal manures with up to 30 percent solids and sewage sludge
with up to 20 percent solids have been unloaded. Because the
hydraulic power is limited, the full performance capabilities
of the 12-inch auger have not been determined. A spreader
can be installed on the rear for land spreading.
A ridge-and-furrow opener can be mounted on the
3-point hitch of the tractor or mounted on the tongue of the
trailer. This consists of right-hand and left-hand moldboard
plows, bolted together on the same trip-release beam. The
12-inch opening in the center of the trailer tank permits a
high capacity application of semisolids into the furrow.
Presently the furrows are closed or covered in a second opera-
tion.
The best equipment field-tested to date at the New
Jersey Experiment Station, for unloading semisolids and cake
with more than 25% solids, is a New Idea Flail Spreader. It
can be adjusted for a wide range of surface applications,
which are plowed under in a second operation. A conveyor
similar to the one on a forage wagon is being adapted to this
spreader to convey the waste into a furrow for PFC.
International Harvester sells an attachment to convert
one of their heavy-duty manure-spreaders into a self-unloading
forage wagon. At this time it has not been demonstrated for
unloading a gummy, sticky semisolid into a furrow.
There should be no difficulty in adapting either of
these pieces of equipment to PFC for either one or two operations,
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Plans are underway at the New Jersey Agricultural Experiment
Station to make these adaptations.
There are outstanding advantages in handling dewatered
sludge with a solids content of 15% or greater.
(I) As solids content increases, volume and weight
decreases. For example, to inject one ton of solids in a 5%
solution, twenty tons of slurry must be handled; for one ton
of solids in a 15% solution, 6-2/3 tons; and only 3-1/3 tons
if a semisolid with 30% solids, dry-weight basis.
(2) It can be stored in contoured furrows or piles
on well-drained sites to be incorporated into the soil when
weather and soil conditions are optimum.
(3) It can be transported in regular dump trucks
without leakage on the highway.
(4) Sludge with a solids content of 15% represents
the minimum solids content which can be incorporated into the
soil by PFC at the rate of 40 tons dry-weight equivalent per
acre in one application: i.e., 2.27 inches of det>th in the
furrow can be completely covered. Greater rates "of applica-
tion can be applied in one operation if the sludge contains
less moisture and more solids, and also because greater depths
can be covered in the furrow. This rate of application repre-
sents the performance capabilities of the equipment and not
necessarily the optimum or safe amount which the soil can tie
up, degrade and recycle. Smaller quantities can be applied.
In order to utilize the continuous output of sewage
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treatment plants, daily PFC applications at the desired annual
rate may be made in contiguous strips or furrows, resulting in
the entire plot receiving the total annual treatment. At any
time when there is sufficient area of contiguous strips of
plowed ground, it may be disked and seeded to the crop appro-
priate for that particular season. After some forage crops,
e.g., Hybrid Bermuda Grass, have been established, one or two
applications can be made annually by PFC or SSI without re-
planting. For maximum recycling and utilization of nutrients
from the sludge, crops should be raised on and harvested from
the treated sites when mature or at the end of the period of
their maximum assimilation. Numerous crop management plans
and rotations are possible, depending upon the sites and the
end product desired.
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References
Meadows, Donella H., D.L. Meadows, J. Randers,W.W. Behrens III,
"The Limits to Growth." A report for the Club of Rome's
project on the Predicament-of Mankind. Universe Books,
New York, 1972.
Bohn, Hinrich L., R.C. Cauthorn. "Pollution: The Problem
of Misplaced Waste", American Scientist, Vol. 60, pp. 561-565,
Sept.-Oct., 1972.
Stevens, R. Michael, D.J. Elazar, Jeanne Schlesinger,
J.F. Lockard, and B.A. Stevens, "Green Land-Clean Streams",
Center for the Study of Federalism, Philadelphia, Pa., 1972.
Hinesly, Thomas D. and B. Sosewitz, "Digested Sludge
Disposal on Crop Land", 41st Annual Convention, Water
Pollution Control Federation, Chicago, Illinois, Sept., 1968.
"Recycling Sludge and Sewage Effluent by Land Disposal."
Environmental Science and Technology, Vol. 6, No. 10,
Oct., 1972.
Reed, Sherwood C., P. Murrman, F. Kortz, W. Richard, P. Hunt,
T. Buzzell, K. Carey, M. Bilello, S. Buda, K. Guter, and
C. Sorbor. "Wastewater Management by Disposal on Land."
Special Report 171, Corps of Engineers, Cold Regions
Research and Engineering Laboratory, Hanover, N. H., 1972.
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SLUDGE DISPOSAL STUDIES AT BELTSVILLE
by John M. Walker^ £/
y Soil Scientist, Biological Waste Management Laboratory, USDA,
ARS, AEQI, Beltsville, Maryland 20705
2/ Other contributors to this work include W. D. Burge (Soil
Scientist); R. L. Chaney (Plant Physiologist), E. Epstein
(Soil Scientist); and J. D. Menzies (Laboratory Chief),
Biological Waste Management Laboratory; George B. Willson,
(Agricultural Engineer) USDA, ARS, College Park, Maryland;
D. F. Bezdicek, (Assistant Professor, Soil Chemistry) Dept.
of Agronomy, University of Maryland, College Park, Md.
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SLUDGE DISPOSAL STUDIES AT BELTSVILLE
by J. M. Walker
Our research at Beltsville on the use of dewatered sewage sludge
for soil improvement has been a cooperative study involving the Agri-
cultural Research Service (ARS), tho Maryland Environmental Service (MES),
the Environnental Protection Agency (^PA), and about 15 other state, local
and federal agencies. I will be highlighting results of U different field
studies and a number of laboratory studies.
The goal of our research has been to use sewage sludge to improve
soils at a reasonable cost, with mininujp hazard to health, and with mini-
mum soil and water pollution. We also have been very interested in help-
ing the Blue Plains sewage treatment facility, which serves much of the
Washington Metropolitan Area, find a use for the 600 tons of dewatered
sewage sludge produced each day (20£ solids). This much sludge can cover
a football field to a depth of about 3 feet in 10 days.
With this much sludge to dispose of, our primary concern necessarily
has been with what limits the amount of sludge that you can safely apply
to soils. We have grouped these limitations into two categories. The
first category includes short-term limitations: The initial toxicity of
sludges to plants, pathogen presence and survival, and excessive quantities
of nitrogen. The second category is toxicity from heavy metals such
as zinc, cadmium, copper, and nickel, which limit the amount of sludge
that you can add to the soil in the long run. These heavy metals, which
are present in the sludge, can injure and kill plants and possibly even
cause food chain problems.
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One method for incorporating sewage sludge in soil has been by
plowing, disking or rototilling. We began application studies in
October 1971- In a preliminary unreplicated experiment, ve mixed
a digested sewage sludge from Blue Plains into a fill clay soil to
the 2-foot depth at rates fron 0 to 160 dry tons per acre. Soil was
excavated with a bulldozer, a layer of sludge was spread with the
dozer and rototilled in, then a layer of soil was spread on top.
This process was repeated until the 2-foot depth of incorporation was
completed. Although the rates of application are stated as dry tons
per acre, dewatered filter cake sludge with 80^ liquid content was
used in this and all other experiments.
Rye was planted immediately after sludge incorporation. Growth
of rye was best on the area receiving Uo dry tons of sludge per acre
(rye vegetative growth in May was 7-^ tons dry matter per acre). There
was respectively less growth at 80, 120 and 160 dry tons sludge per
acre (5-9, 3.*+ and 3.2 tons dry matter per acre). Growth on the con-
trol where no sludge and little nitrogen fertilizer was applied was
even lower (0.9 ton dry matter per acre). Rye growth on the control
contrasted sharply with growth on the area receiving 80 dry tons per
acre (Figure l).
Sweet corn and Kentucky 31 tall fescue were grown on these same
plots in June following the rye. Growth of both fescue and corn was
worse than that of rye where no sludge or little nitrogen fertilizer
was added (fescue yield was too small to measure).
""orn yields were not determined because of the limited area planted
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but a good sampling of fescue van possible. First cutting yields of
fescue were 1900, 2000, 2700, and 3300 pounds per acre for treatments
of UO, 80, 120, and 160 dry tons of sludge per acre respectively.
We believe that hir.n applications rates of sludge reduced rye yields
because of the initial toxic effects on growth. These initial toxic effects
may be caused by high saJts, high ammonia, low oxygen, and toxic anaerobic
breakdown products such as rr.ethane gas and hydrogen sulfide. The initial
toxic effects apparently had subsided by the time fescue and sweet corn
were grown.
In a different experiment, digested sludge was disked into the sur-
face 6 inches of a loamy soil at rates of 0, 25, 50 and 100 dry tons per
acre. This research was conducted cooperatively with the University of
Maryland on their plant research farm. Growth of soybeans and field corn
was very good at both the 25- and 50-ton rates. However, growth of
the soybeans, in particular, was reduced by one-half at the 100 ton sludge
rate. We believe this is another example of an initial toxic effect of
sludge on crop growth.
We also studied the survival of microorganisms in the sludge
that was added to the clay soil. Table 1 shows that fecal coliform
organisms persisted for as long as 15 months before they could no longer
be detected in the soil. We also wanted to determine whether these micro-
organisms would move down through the clay soil into the well water about
10 feet below the soil surface. Thus far we have not detected any sludge
microorganisms in this well water, nor have we detected any nitrogen
moving down from the sludged soils into the well water.
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We have also been investigating the effect of these sludge amendments
on heavy metal uptake by different plants. We found that Swiss chard
absorbed nearly 10 times more zinc than did fescue (Table 2). When
soils were limed to pH 7 as compared to 5«5» plant uptake of metals was
reduced two- to sixfold. This illustrates two very important points to
be considered when growing crops on sludged soils. First, soil pK must
be maintained near neutral, and second, crops must be selected that
will not absorb excessive quantities of heavy metals. Results of an
analysis of the Blue Plains sludge (Table 3) show that although the
heavy metal concentration does not make this sludge unsuitable for use
on soils, it does lii.iit the amount that can be applied safely.
Higher rates of sludge application were desired than we could
achieve by mixing the sludge into the soil surface. Also, much of the
sludge from Blue Plains is raw rather than digested. Therefore, we
investigated a trenching technique as an alternative method for incor-
porating sludge into the soil.
In May 1972, sludge was placed in trenches that were either 2 feet
wide, U feet deep and 6 feet apart on centers (500 dry tons/acre), or
2 feet wide, 2 feet deep and U feet apart on centers (320 dry tons/acre).
Sludge was placed in trenches with a front-end loader. A trenching
machine simultaneously dug a trench and covered the previous sludge-
filled trench. This soil, when evenly spread over the sludge-filled
trenches and intervening soil, provided a 12- to 15-inch soil cover which
eliminated both contamination of surface water and odor, buried disease-
causing organisms, and permitted digestion of the sludges in the field
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'(thereby reducing the population of disease organisms). The trenched
sludge apparently has remained anaerobic since incorporation except
at the edge of each trench. Thus, mineralization of nitrogen has been
slow and denitrification apparently has been occurring. Up to 500 dry
tons of sludge per acre can be applied in one shot deep in the soil
profile by trenching. This lovers the cost of the operation and
restricts additional sludge application unless future tests show that
it is safe to do so.
Roots of crops that were planted over the trenched area could grow
into the sludge or into the soil. This was particularly important be-
cause roots will not readily grow into raw sludges until considerable
field digestion has occurred. Meanwhile, roots that grow down between the
trenches can benefit from nutrients released slowly from the sides of the
trenches. Observations indicated that this was true for the fescue,
corn, and fruit trees grown on these plots.
About kO groundwater wells were installed in an area of approximately
75 acres. These were monitored before and after sludge application to
determine the extent of any possible pollution from nitrogen or micro-
organisms. The plot area covered about 5 acres of the 75-acre site. Sur-
face and groundwater were drained into a catchment pond. Samples from
the pond and pond drainage stream were taken periodically, and analyzed
for nitrogen, chemical constituents, viruses, and microorganisms. There
has been little contamination of the pond or wells with nitrogen or
microorganisms. However, one well, immediately adjacent to a raw sludge
plot, has shown increased levels of nitrogen (up to 22 ppn N03 nitrogen)
106
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and microorganisms, indicating contamination from the plot. The subsurface
drainage system also is intercepting some contaminated groundwater (10
ppn N0_ nitrogen). If any significant contamination with disease organ-
isms or nitrate occurred, the ground water could be chlorinated, or filtered
by applying on surrounding land. Thus far, hovever, such measures
have not been necessary.
Possible movement of nitrogen or microorganisms from the trenches
was investigated further by digging a pit at right angles across the
incorporated sludge in the trenches. The soil and sludge were analyzed
at specific locations in and around the trench. Analyses of these samples
showed little movement of nitrogen or coliform organisms beyond about
2 feet from the bottom of the trenches. Studies of persistence of
disease organisms in these trenches showed that salmonella organisms
persisted for at least 7 months. Although the salmonella organisms
did persist, they would also persist if the sludge were landfilled or
dumped into waterways. It is encouraging that epidemiological evidence
has not indicated adverse effects on human health in areas where digested
sludge has been applied to soils as fertilizer. More research is needed,
and our sampling for persistence is continuing.
We have run field studies on the effects of liming sludges up to
pH's of 11.5 before incorporating then into the soil. Although initially
the high lime nearly eliminates salmonella and fecal coliform organisms,
the remaining organisms appear to multiply within a month as the pH drops
to 7.0 or 8.0. The microorganisms then were at comparable or even
slightly higher levels than in the sludges that had not been limed
to such high pH's. Therefore, liming sludge to pH 11.5 is not adequate
to insure that sludge microorganisms will be eliminated.
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I would express a note of caution on the results with pathogens,
nitrates, and heavy metals in the field. The studies are continuing and
results may differ with time.
Although the trenching system is technically feasible and offers a
solution to the problem of sludge disposal, it may not always be accept-
able to residents in an area where the system might be used. This
emphasizes the necessity for participation by local citizens and their
elected officials in planning the solutions for waste problems.
Another alternative for sludge disposal is composting. In September
1972, we learned that equipment was available for large-scale field com-
posting of materials like sewage sludge. In fact such equipment had been
used in Los Angeles for this purpose. We believe that composting may be
a solution to the sludge problem at Blue Plains.
ARS and MES held a public meeting to explain their plans for a
cooperative research demonstration project. We expected to develop tech-
nology for composting up to 600 tons of dewatered sewage sludge per day
and to study its safety and proper agronomic use. We told the audience
that sludge had been dried and essentially composted in the Los Angeles
area and then marketed successfully over the past kO years. We indicated
that our goal was not necessarily to produce a marketable product but
rather to produce a product that could be disposed of more safely than
rav or digested sludge. The project was accepted by the public.
In preliminary studies we have been developing methods for composting
sludge. Briefly, the procedure involves mixing a bulking agent such as
paper, sawdust, or woodchips with the sludge in the ratio of about 3 parts
bulking agent to 1 part sludge. In this manner the initial 80 percent
108
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moisture content of sludge is reduced to 60 tp 65 percent. Because
air can readily penetrate this "blended mixture of sludge and "bulking
agent, the sludge decomposes rapidly without generating objectionable
odors. The thermophillic microbial activity generates temperatures up
to about 150°F. The heat drives off excessive moisture and has a pasteur-
izing effect on the pathogens present in the sludge. Pathogens are also
killed by the antibiotics produced during composting.
An isolated site previously used as a burn dum]j and landfill vas
chosen for the large-scale composting project in a wooded area on the
Beltsville Agricultural Research Center. A sketch of the planned compost
site is shown in Figure 2. Basically, a stabilized compost pad of about
5 acres should permit the composting of sewage sludge at the rate of 250
tons per day. Windrow-composting will be accomplished with a General
Motors-Terex Cobey^- composting machine which has a high volume output.
Sludge and bulking agent will be mixed and composted on the pad for approxi-
mately lU days. We expect that conposted sludge can be utilized as a
bulking agent for new additions of sludge. This recycling of the compost
as a bulking agent is a key to the success of the operation.
Once operations reach the 250-ton-per-day level, the excess compose
that is not needed for bulking will be moved to the 2- or 3-acre storage
area and stored in a huge pile for curing. During curing, some additional
composting takes place and high temperatures can be reached for a final
pathogen kill. After storing and curing for approximately 1 to 2 months,
the sludge will be made available for distribution — maybe even to home-
owners if tests show it be be safe.
J3/ Trade names are used for the benefit of the reader and do not imply
endorsement by the U.S. Departr.ent of Agriculture.
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We will be studying the fate of pathogens, nitrogen, carbon, and
heavy metals during the composting and curing processes. We also vill
"be studying the agronomic and horticultural use of the compost.
I did not have time today to cover all of the interesting work we
are doing on this project at Beltsville. I hope that you will visit with
us here today and at Beltsville if you would like to know more about our
work.
Thank you very much.
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Table 1. Fecal coliform survival in digested sludge-amended
clay soil. (Sludge incorporated October 1971).
Sludge
dry tons/acre
in surface
2 ft.
Fecal coliform, cells/g
5 months
March 1972
9 months
July 1972
13 months
Nov. 1972
15 months
Jan. 1973
Control
80
120
160
<0.03
1,500
27,000
2*4.,000
350
2*4-0
k
19
56
k
0.02
<0.02
<0.02
<0.02
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Table 2. Zinc uptake by Swiss Chard and fescue on sludge-amended
soil with and without lime
Sludge applied Zinc uptake, ppm
tons/acre in Swiss Chard Fescue
surface 2 ft. No Lime Lime No Lime Lime
0 60 31
1+0 - 150 68 38
80 1050 18U 83 3$
120 19^0 566 86 te
160 1690 627 112 198
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Table 3- Heavy metal and nutrient concentrations in digested sludge
from Blue Plains sewage treatment plant.
Heavy metals Macronutrients Micronutrients
ppm 'jo ppm
Zn
Cu
Mn
Ni
Cd
2000
1100
180
100
20
N
P
K
Ca
Mg
S
2.5
1.0
0.5
1.5
1.0
0.9
B 23
Mo 8
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LIST OF FIGURES
Figure 1. Yield of rye, May 1972; planted October 1971. Digested
sewage sludge was incorporated into the surface 2 feet at 0
(left) and 80 (right) dry tons per acre.
Figure 2. Field composting site on the Agricultural Research Center
at Beltsville.
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Figure 1,
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
115
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Figure 2.
INITIAL COMPOST PAD
PAD EXPANSION
COMPOST SITE
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MERCHANDISING HEAT-DRIED SLUDGE
C. G. Wilson, Sales Manager £ Head Agronomist
Sewerage Commission, City of Milwaukee
Eight days before this meeting I was adjusting sludge
blankets in our East Plant clarifiers, running effluent chlorine
residuals, and increasing chlorination levels in both East and
West plant effluent to assure citizen safety in drinking water
supplies. At the same time I was helping to destroy some
$8,500.00 worth of sludge that should have been made into Mil-
organite.
Poor sales, and or, poor merchandising were not the reasons
for these special actions on my part. We had a municipal strike
on that Sunday in question, and it became management's duties
with limited help to worry first about water purification.
Incidentally, and whether or not it would be a function
of the E.P.A., someone should be making in depth studies on
methods other than strikes to solve municipal labor problems.
The strike certainly solves the problem of waste disposal for
those located on water courses, but is hardly the way to go
today.
We elected to go the route of heat-dried disposal in the
early 1920's. In fact, Milwaukee pioneered the activated
method of sewage disposal, and from the start anticipated a
market for the by-product to help offset costs.
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The Annual Report of the Sewerage Commission for the year
1923 mentioned investigations underway at the University of
Wisconsin to determin- the by-products fertilizer value, and the
establishment of a fellowship for a Mr. 0. J. Noer to work on
the project. The late Mr. Noer later became our Agronomist and
was recognized as this country's foremost turfgrass agronomist.
He also preceded me as Sales Manager for the Commission.
In the 1925 Annual Report our Commission was advised that
as a result of a six months contest the trade name "Milorganite"
was chosen over 232 other names suggested for the by-product.
The fertilizer brokerage firm Me Iver & Son of Charleston, South
Carolina won the $250.00 first prize for suggesting "Milorganite"
which embraced the words Milwaukee - Organic - Nitrogen.
The first Milorganite (500 tons) was sold in 1926. Since
then, with but two exceptions we have sold everything we can
produce in a given year. I have a Sales, Traffic, and Invoicing
staff of five. We do approximately a 3-1/2 million dollar a
year business, with sales offsetting about 25% of our operating
budget. The sales exceptions were a couple of years during the
depression and again in the mid 1960's. During the early de-
pression no one had money for fertilizer used primarily on
turfgrass, and in the mid 60fs production suddenly jumped from
69,000 tons to 87,000 tons per year. It took us a bit over a
year to sell the increase. Fortunately, we can store about
20,000 tons in bulk on Jones Island.
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Production has slipped since the high year because we are
now diverting some of the gallonage that used to come to our
Jones Island Plant to the new South Side Plant where no Mil-
organite is produced.
The fact that we chose another way to go at the South Side
has not gone unnoticed by many who thought activation and by-
product sale is the only way to go.
In 1964, a production year similar to 1971, it cost us
about $9.00 to dispose of a ton of Milorganite. In 1971 the cost
exceeded $27.00 per ton. During this period I increased our
distributor cost by about $8.00 per ton despite a declining
organic market internationally, and depressed prices for
chemical or inorganic fertilizer because of over production.
The reason for such bad news despite successful sales is
our high fixed cost, increasing wages and fringe benefits, and
inability to offset this with increased production.
The unfortunate point, and this, incidentally, is my
opinion only, was our decision not to produce Milorganite at
•f
the South Side Plant. I should also say, that at the time this
decision was made in the early 1950's, primary treatment would
suffice, and an automated digested gas producing plant seemed
the most economical approach to Milwaukee's growth. What with
the need for secondary and tertiary treatment, today, and our
inability to get rid of the sludge in lagoons would make some
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with hindsight question the wisdom of this decision.
Our South Side lagoons are filling rapidly and the initial
offer to remove their contents when converted to a dry (less than
5% moisture) basis as Milorganite is sold exceeded $70.00 per
ton just to haul it away.
So, from this standpoint it is still economical to sell
Milorganite, and in my opinion is still the best way to purify
an effluent and completely recycle a worthwhile fertilizer
through stimulating plant growth.
Increased production would be the best answer to our high
costs. There is a limit as to how much further increase in
price will be accepted prior to increases being made by the
fertilizer industry.
For example, the large institutional or farm type purchaser
is aware that the cost formula favors the use of the pure
chemical source of high analysis. One takes the cost per ton
and divides this by the % nitrogen in the product times 2,000
the pounds in a ton. If, say, Urea is selling for $90.00 per
ton its cost of nitrogen (45%) then comes to 10$. In some
areas Milorganite (6% nitrogen) sells for the same amount,
thus its nitrogen cost becomes 75C, or 7-1/2 times greater.
Our customers are not ignorant. The reason Milorganite
can command this premium is that it does a better job.
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Several other things have conspired through the years to
help our marketing activity. As with any other successful
merchandising effort luck has also played a part.
In the late 1920's and through the 1930's natural organic
materials were part of all mixed fertilizers. As higher
analysis materials became available to dry up this market our
golf and lawn sales increased. Then, shortly after World War
II started, chemical nitrogen sources went to war and ours was
about the only nationally sold product available for victory
gardens, lawns, etc.
As the highly advertised lawn fertilizers became available
following the war, coupled with our inability to furnish the
demand, we started to lose some place in the lawn market but
this was rapidly absorbed by our golfing friends. And today,
the environmental interests of our citizens makes a yearly
application of Milprganite almost the patriotic thing to do.
Through all of this we also had time to develop a strong
distributor service. All of our distributors are on restrictive
quotas, or allocations; constantly clamor for more product;
and are financially sound so they pay invoices promptly.
However, before anyone dashes out to build their plant
certain sobering figures must be considered.
Alvord, Burdick and Howson (consulting engineers) in a 1956
report to our Commission stated it would cost 50 million dollars
to build a 50 million gallon per day capacity activated plant
from input through incineration. We conservatively estimate
our investment in Jones Island at 80 million dollars, and if
A, B £ H's estimate is correct it would have taken 200 million
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to duplicate our facilities in 1956 and we know how much costs
have gone up since then.
Our dewatering costs with the present plant paid for exceed
$20.00 per ton, and freight on a 50-ton rail car from Milwaukee
to the West Coast exceeds $26.00 per ton. Although the customer
pays for the latter, one must think about freight costs,
constantly, when dealing with low analysis materials.
My best guess is that under present costs and prices our
production and sales would have to exceed 100,000 tons a year
to reach a break even point. I am sure we could find a market
for this much Milorganite. Others might not find it so easy.
They would have to establish markets, assure supply, maintain
quality control, and stay free from political pressures.
All sewage sludges are by no means alike. Granulation is
important to the applicator and the plant being grown. Our
industrial complex is responsible for an additional one to two
percent nitrogen over what other cities might be capable of
producing.
In summary, then, the following have been important to us
in merchandising heat dried activated sludge.
I. Knowledge of what the by-product will do in growing
plants. Possibly more important knowledge of what
it won't do.
2. A national market to even out seasonal and climatic
variables.
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3. Quality control and absence of political interference.
H. Sales based on agronomic service rather than wheeling
and dealing.
5. A strong distribution system.
Slides were shown proving the superiority of Milorganite
over other nitrogen sources in growing quality turfgrasses.
Milorganite fertilized grass had less disease, insect and water
stress injury in tests at leading Agriculture Experiment
Stations throughout the nation.
CGW/bmr
Prepared for E.P.A. - Rutgers Meeting
March 12 8 13, 1973.
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OUTLINE OF PRESENTATION MADE BY MICHAEL GRITZUK, P.E.,
EXECUTIVE DIRECTOR, OCEAN COUNTY SEWERAGE AUTHORITY
AT THE~T'LAND DISPOSAL OF MUNICIPAL EFFLUENTS AND SLUDGES "SEMINAR"
ON MARCH 12, 1973 AT RUTGERS UNIVERSITY
OCEAN COUNTY SEWERAGE AUTHORITY
WASTEWATER SOLIDS UTILIZATION ON LAND DEMONSTRATION PROJECT
A. INTRODUCTION
1. The Ocean County Sewerage Authority will shortly start
construction of a county-wide regional sewerage system
that:
a. Will serve 33 municipalities which will have a
combined design population of approximately
800,000 people by the year 1990.
b. Will have four regional treatment facilities with
a combined design flow of 92 MGD.
c. Will produce 60-70 dry tons of sludge daily or nearly
25,000 dry tons per year.
2. Since the Authority's creation in July 1970, we have been
asking ourselves "How will we dispose of the 25,000 dry
tons of sludge in light of recent developments, contro-
versies and restrictions on sludge disposal?"
We have been faced with finding a feasible, economical, and
from an environmental viewpoint, the most desirable solution
for the disposal of wastewater solids.
In addition, the 1972 Amendments to the Federal Water
Pollution Control Act indicates the national "goal" is
to totally recycle wastewater and its byproducts.
B. PRELIMINARY INVESTIGATIONS
1. Several geographic features of Ocean County that should be
known before we discuss a sludge reuse plan:"
a. Primarily flat terrain
b. Almost entirely sand
Preceding page blank
125
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c. Densely populated along coastal area. Non-populated
barren land in western part of County.
d. Pine barrens in nutrient deficient soil.
2. The Authority established criteria requiring that whatever
sludge disposal method is chosen must be:
a. Environmentally desirable
b. Economically feasible
c. Publically acceptable.
3. From the preliminary evaluations of various methods of sludge
disposal, which included barging to sea, incineration and
landfill, it was concluded that sludge utilization or reuse
was definitely worth evaluating for Ocean County.
C. DEVELOPMENT OF DEMONSTRATION PROJECT
1. During the past few years we were able to solicit the support
of Federal and State agencies to develop a pilot project to
demonstrate that sludge reuse is possible, economically
feasible and environmentally desirable in Ocean County.
2. The participants in the demonstration project are:
New Jersey Division of Environmental Quality
New Jersey Division of Fish, Game and Shell Fisheries
New Jersey Division of Water Resources
Ocean County Sewerage Authority
Rutgers University
U. S. Environmental Protection Agency
U. S. Geological Survey
3. In June 1972, The Ocean County Sewerage Authority received
a $200,000 demonstration grant from the U. S. Environmental
Protection Agency for its project entitled:
"Wastewater Solids Utilization on Land
Demonstration Project."
126
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D. BENEFITS OF RECYCLING
Initial research of existing data indicates that certain
benefits can be derived from utilizing sludge. In partic-
ular for the barren leached-out Ocean County soils, the
following benefits appear likely:
1. Can build up the organic content of arid and
marginal soils.
2. Acts as a mild fertilizer by providing nutrients
to the soil.
3. Can supply moisture-retaining capabilities to leached-
out soiIs .
4. Acts as a soil conditioner.
5. Encourages the growth of more desirable vegetation.
6. Reclaims land for more productive purposes such as
food production for wildlife, recreation and crop
production.
7. Economical.
E. SLUDGE FOR REUSE
1. Only anaerobically digested domestic sludge will be used.
Standard Rate two-stage digestion will be utilized which
will have an average detention period of 30 days in primary
digestion and 15 days in secondary digestion.
2. Characteristics of anaerobically digested sludge:
a. Reduces pathogenic bacteria populations by 99.8%
b. Reduces BOD by at least 901
c. Emits little odor
d. Easier to handle through pipelines and spray
equipment.
3. The digested sludge will be applied in the wet state which
will normally consist of 4 to 6 percent solids.
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F. • GOALS OF THE DEMONSTRATION PROJECT
The primary goals which will be thoroughly investigated in
the project are as follows:
1. Determine proper equipment and application techniques.
2. Determine quantity and frequency of application.
3. Determine any pollutional effects on ground water.
4. Establish ground water quality standards.
5. Determine value of wastewater solids as a fertilizer
and soil conditioner for crop production and scrub
pine and oak growth.
6. Public education and public acceptance.
7. Aesthetic evaluation.
8. Evaluate long-term effects.
G. PROJECT ACTIVITIES
The activities of the three and one-half year project are:
1. Site selection
Three distinct soil types which are common to the
eastern seaboard will be evaluated. These soils are:
a. Lakewood sand.
b. Woodmansie sand and sandy loam.
c. Downer sandy loam, slight clay.
2. Evaluation of application methods
Various methods of application will be evaluated in
light of practicality, economics and minimal environ-
mental hazards. As a minimum, the following methods
will be evaluated:
128
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a. High pressure spray method (Rain gun).
b. Contoured furrows.
c. Plow-furrow-cover method.
d. Sub-sod-injection method.
3. Hydroligic and geologic characteristics of test sites-
ground water monitoring.
A major evaluation in the project will be to determine
the effects of the wastewater solids on the ground
water. Test wells will be located within and around
each test site to permit sampling of the ground water
before, during and after the application of any solids.
Before the application of any solids the subsurface
geology will be mapped, ground water flow nets will
be determined and charted. Base-line ground water
quality will continuously be determined at the control
plot. A typical layout of the test plots and control plot
is shown in Figure 1.
The parameters to be tested and monitored in determining
the baseline ground water quality is shown in Figure 2.
4. Survey of soil conditions and vegetation.
Planting of agricultural crops.
Soil testing will be performed before and after application
of solids and after crops have reached maturity. Plant
tissues will be analyzed to determine any buildup of chemi-
cal and biological constituents.
5. Atmospheric and meteorological monitoring.
Atmospheric monitoring will include gaseous ammonia and
particulate aerosol samplings and odor measurements. This
is particularly important in respect to bacterial-aerosol
transmission if spray equipment is to be us'ed.
129
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130
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FIGURE 2
GROUND WATER MONITORING
Coliform (total, fecal)
Virology
Dissolved solids (fixed, volatile)
Nitrogen (Kjeldahl, organic, N07, NO,,
NH4)
Phosphorous (Total, PO )
Alkalinity
Hardness
Bicarbonate (HC03)
Total Organic Carbon
Chloride (Cl)
Fluoride (F)
Metals (Hg,Zn,Cr,Mn,Fe,Mg,Pb,Cd,Cu,Ni,Al)
Temperature
PH
Turbidity
ABS
Specific Conductance
Silica (Si02)
Potassium (K)
Sodium (Na)
Calcium (Ca)
Sulfate (SO )
Boron (B)
131
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6. • Determination of loading rates and application frequency.
Optimum loading rates will be determined based upon
crop growth, lan^ reclamation values and ground water
loading. The frequency of application will be determined
by crop utilization of nutrients and soil assimilation
capabilities.
Initially loading rates of 10, 20 and 40 dry tons/acre/year
will be utilized. Adjustment of these rates may be warranted
after approximately 12 months of data is available.
(10 dry tons/acre/year = 2 inches 5% sludge = 3/16" dried)
7. Effects on wildlife; aesthetic evaluation; public
acceptance.
A study of wildlife will be made to determine their
preference, if any, for fertilized vegetation. Aesthetic
value will be determined by reaction of the public. Public
opinion will be solicited at general public meetings, semi-
nars, and through the news media.
To conclusively determine the effects of recycling wastewater
solids on land, it is expected that in excess of 150,000 analyti-
cal tests will be performed in the 3 1/2 year evaluation period.
H. COST COMPARISON
A cost comparison of wastewater solids recycling to the more
popular sludge disposal methods are as follows:
REUSE ON LAND (5% Solids) $19.*
LAGOONING $18,
OCEAN DISPOSAL (Digested, 10% Solids) '$28,
LANDFILL (Dewatered $ Digested) $35,
INCINERATION (Dewatered, Raw) $40
DISPOSAL THROUGH OUTFALL (Raw) $ 1
*Capital and operating cost, $/Dry Ton
132
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EPA VIEWPOINT
ON
LAND APPLICATION OF LIQUID EFFLUENTS
by
John R. Trax
Treatment and Control Optimization Section
Municipal Technology Branch
Office of Research and Monitoring
Environmental Protection Agency
Washington, D. C. 20460
133
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EPA VIEWPOIN1 ON LAND APPLICATION OF LIQUID EFFLUENTS
I AM PLEASED TO PARTICIPATE IN THIS CONFERENCE ON LAND DISPOSAL
OF MUNICIPAL EFFLUENTS AND SLUDGES BECAUSE OF THE DEEP IMPORTANCE OF
ITS CENTRAL THEME. IT FOCUSES ON AN AREA OF TECHNOLOGY THAT HAS BEEN
WITH US FOR MANY DECADES BUT HAS MORE RECENTLY GAINED IMPORTANCE DUE
TO THE EVER INCREASING AWARENESS OF ENVIRONMENTAL ISSUES.
IT IS ENCOURAGING TO SEE COUNTY AND MUNICIPAL SANITARY ENGINEERS,
OFFICIALS AND MANAGERS OF RESEARCH PROGRAMS, MEMBERS OF UNIVERSITIES
AND CONSERVATIONIST COMMUNITIES HERE TO BECOME ACQUAINTED V/ITH THE
CURRENT STATE OF THE ART, RECENT TECHNICAL ADVANCES AND ACTUAL FIELD
EXPERIENCE IN DISPOSAL OF MUNICIPAL EFFLUENTS AND SLUDGES ON THE LAND.
IN MY TALK THIS MORNING, I WILL ATTEMPT TO CONVEY TO YOU THE
ENVIRONMENTAL PROTECTION AGENCY'S VIEWPOINT ON LAND TREATMENT OF
MUNICIPAL EFFLUENTS. I WILL PRIMARILY BE SPEAKING FROM MY PERSPECTIVE
AS A PERSON INVOLVED IN THE MUNICIPAL TECHNOLOGY RESEARCH PROGRAM. MY
ASSOCIATE, MR. RALPH SULLIVAN, CHIEF OF CONSTRUCTION GRANTS BRANCH,
OFFICE OF AIR AND WATER PROGRAMS, WILL BE ADDRESSING THE ISSUE FROM THE
CONSTRUCTION GRANTS SIDE OF THE EPA PROGRAM.
AT THE OUTSET, WE SHOULD TAKE NOTE OF THE ASTOUNDING GROWTH OF THE
ENVIRONMENTAL MOVEMENT DURING THE PAST TWO AND ONE-HALF YEARS. IT WAS
INDEED JUST A LITTLE OVER TWO YEARS AGO THAT THE ENVIRONMENTAL PROTECTION
AGENCY ITSELF CAME INTO BEING THROUGH A REORGANIZATION PLAN - ADOPTED BY
PRESIDENT NIXON. SHORTLY THEREAFTER, THE CLEAN AIR AMENDMENTS OF 1970 WERE
ENACTED. AT THE END OF THIS PAST SESSION, CONGRESS ENACTED A NEW FEDERAL
WATER POLLUTION CONTROL ACT. IT ALSO ENACTED MAJOR NEW LEGISLATION TO
REGULATE OCEAN DUMPING, NOISE, PESTICIDES AND COASTAL ZONE MANAGEMENT.
134
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THE IMPACT OF THESE NEW LAWS IS AND WILL BE MOMENTOUS. ESPECIALLY
IN REGARD TO AIR AND WATER POLLUTION, THESE LAWS SPELL OUT THE STATUTORY
AUTHORITY FOR A TRULY COMPREHENSIVE, FAR REACHING COSTLY NATIONAL EFFORT
TO ACHIEVE BRIGHT SKIES AND SPARKLING WATER. BOTH LAWS ESTABLISH BOLD
STRUCTURES OF REGULATION TO DEAL WITH EXISTING POLLUTION PROBLEMS AND
ALSO NEW SOURCES. WITHOUT QUESTION, THEY SET THE STAGE FOR A DECADE ON
CONCENTRATED ENVIRONMENTAL RECONSTRUCTION.
THE AMENDED FEDERAL WATER POLLUTION CONTROL ACT IS OF PRIMARY CONCERN
FOR US TODAY. IT ESTABLISHES A NEW REGULATORY SCHEME, BASED PRIMARILY ON
A NATIONAL EFFLUENT DISCHARGE PERMIT SYSTEM FOR ALL MUNICIPAL, INDUSTRIAL,
AND CERTAIN OTHER DISCHARGERS. THE ACT DIRECTS THE ACHIEVEMENT BY
JULY 1, 1977, OF EFFLUENT LIMITATIONS FOR DISCHARGES WHICH REQUIRE
APPLICATION OF BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE,
AND THE ACHIEVEMENT BY JULY 1, 1983, OF EFFLUENT LIMITATIONS WHICH REQUIRE
BEST AVAILABLE TECHNOLOGY. THE LAW SETS FORTH AS A LONG RANGE GOAL, BUT
NOT A REQUIREMENT, THE ACHIEVEMENT OF "NO DISCHARGE" BY 1985.
ANOTHER BILL OF PRIMARY IMPORTANCE TO US IS THE MARINE PROTECTION,
RESEARCH AND SANCTUARIES ACT OF 1972 WHICH WILL HAVE THE IMPACT OF LIMITIilG
OCEAN DISPOSAL OF SEWAGE SLUDGE AND OTHER MATERIAL NOW DISCHARGED TO THE
OCEAN.
I GIVE YOU THIS BACKGROUND INFORMATION FOR IT HAS A GREAT IMPACT ON
DEVELOPMENT OF TECHNOLOGY FOR LAND TREATMENT SYSTEMS. MANY TOWNS,
COMMUNITIES AND CITIES ARE INVESTIGATING THE LAND TREATMENT ALTERNATIVE
FOR TREATMENT OF SEWAGE SLUDGE AND/OR SEWAGE EFFLUENTS.
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LAND TREATMENT CAN MEAN A VARIETY OF THINGS, DEPENDING UPON THE
CONTEXT OF WHAT IS SAID AND WHAT THE LISTENER DESIRES TO HEAR. FOR
THE PURPOSE OF THIS PAPER, LAND TREATMENT IS INTENDED TO BE USED IN
ITS BROADEST CONTEXT AND CONFINED TO ITS USE FOR TREATMENT AND
RENOVATION OF MUNICIPAL WASTEWATERS. SINCE SOLID MATERIALS ARE ONE OF
THE PRODUCTS OF WASTEWATER TREATMENT AND CAN, UNDER PROPER CONDITIONS,
BE APPLIED TO THE LAND, THE APPLICATION OF MUNICIPAL SEWAGE SOLIDS (SLUDGE)
TO THE LAND IS CONSIDERED AN INTEGRAL PART OF LAND TREATMENT.
WITHIN THE ABOVE DEFINITION, LAND TREATMENT CAN BE GROUPED IN THE
FOLLOWING CATEGORIES:
(1) INFILTRATION-PERCOLATION: THE APPLICATION OF MUNICIPAL
EFFLUENTS TO THE SOIL BY MEANS OF RECHARGE BASINS, RIDGE-AND-
FURROW BASINS OR FLOODING BASINS.
(2) CROPLAND IRRIGATION: THE APPLICATION OF MUNICIPAL EFFLUENTS
TO THE SOIL FOR BENEFICIAL PRODUCTION OF CROPS NOT FOR DIRECT
HUMAN CONSUMPTION. COMMON METHODS OF APPLICATION INCLUDE
BROAD IRRIGATION AND SPRAY IRRIGATION.
(3) SPRAY-RUNOFF: THE APPLICATION OF MUNICIPAL EFFLUENT TO THE
SOIL IN A MANNER CONCLUSIVE TO OVERLAND SHEET FLOW IN A .
CONTROLLED MANNER. THE PHYSICAL, CHEMICAL AND BIOLOGICAL
PROCESSES TAKE PLACE AS THE LIQUID MOVES SLOWLY OVER THE SURFACE.
MORE THAN HALF OF THE APPLIED EFFLUENT IS RETURNED DIRECTLY
TO THE SURFACE WATERS.
SOLIDS BENEFACTION: THE APPLICATION OF SOLIDS PRODUCTS
OF WASTEWATER TREATMENT TO THE LAND FOR BENEFICIAL IMPROVEMENT
OF THE SOIL. SUCH APPLICATION MUST BE ACCOMPLISHED IN A MANNER
WHICH IS ENVIRONMENTALLY SOUND AND AESTHETICALLY ACCEPTABLE.
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ACCURATE INFORMATION ON THE EXTENT AND SUCCESS OF LAND TREATMENT
SYSTEMS IN THE UNITED STATES IS DIFFICULT TO OBTAIN AND EVALUATE.
THOMAS RECENTLY SUMMARIZED AVAILABLE DATA ON THE NUMBER OF U. S.
COMMUNITIES UTILIZING ONE OR MORE OF THE LAND TREATMENT METHODS. THESE
DATA INDICATE THAT IN 1972 THERE ARE 571 COMMUNITIES APPLYING WASTEWATERS
TO THE LAND FROM A COMBINED POPULATION OF 6.6 MILLION PERSONS. THIS IS A
SUBSTANTIAL INCREASE FROM SIMILAR DATA FOR 1940, WHEN 304 COMMUNITIES
SERVING 0.9 MILLION PERSONS UTILIZED LAND TREATMENT. AS INDICATED
ABOVE, THE ACCURACY OF THE FIGURES IS SUBJECT TO QUESTION. THOMAS,
FOR EXAMPLE, POINTS OUT THAT ONE LARGE SYSTEM SERVING 654,000 PERSONS
WAS OMITTED FROM THE 1972 DATA - AN ERROR OF 10 PERCENT.
THESE FIGURES ALSO APPLY ONLY TO APPLICATION OF MUNICIPAL EFFLUENTS
AND DO NOT INCLUDE FIGURES FOR LAND APPLICATION OF THE SOLIDS BY-PRODUCTS
OF TREATMENT. CROP IRRIGATION IS THE METHOD USED BY THE LARGEST NUMBER
OF COMMUNITIES (316), IN L3 WESTERN STATES. NATIONAL INVENTORIES OF
MUNICIPAL WASTE FACILITIES IN THE UNITED STATES INDICATE THAT THE
POPULATION SERVED BY LAND TREATMENT FACILITIES NEARLY DOUBLED BETWEEN
1962 AND 1968.
NO ATTEMPT HAS BEEN MADE TO ACCOUNT FOR THE NUMBER OF SEPTIC TANK-
SOIL ABSORPTION SYSTEMS WHICH CAN BE PLACED IN THE INFILTRATION-PERCOLATION
CATEGORY. 40-50 MILLION PEOPLE ARE SERVED BY SUCH SYSTEMS IN THE UNITED
STATES.
SPRAY-RUNOFF SYSTEMS HAVE NOT BEEN UTILIZED FOR TREATMENT OF
MUNICIPAL WASTEWATERS, BUT HAVE BEEN UTILIZED IN THE INDUSTRIAL AREA.
EXPERIENCE GAINED FROM INDUSTRIAL APPLICATIONS INDICATES THAT THIS
TYPE OF SYSTEM MAY ALSO BE APPLICABLE TO MUNICIPAL WASTEWATERS.
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THE 1962 AND 1968 INVENTORIES DO NOT CONTAIN DATA ON THE ULTIMATE
DISPOSAL OF WASTEWATER TREATMENT WORKS SOLIDS. THE 1968 INVENTORY
LISTS 6,893 TREATMENT WORKS UTILIZING SLUDGE BEDS, MECHANICAL DEWATERING
OR LAGOONS AS SLUDGE PROCESSING METHODS. 3,069 FACILITIES ARE LISTED
IN THE MISCELLANEOUS CATEGORY WHILE 4,'t56 PLANTS HAVE NO PROCESSING
FACILITIES OR USE NO ORGANIZED METHOD. WHILE THE INVENTORY CONTAINS NO
INFORMATION ON THE METHODS OF DISPOSAL OF THE DEWATERED SOLIDS, KNOWLEDGE
OF COMMON PRACTICE LEADS TO THE CONCLUSION THAT MOST OF THESE SOLIDS
GENERATED AT A RATE OF OVER 4 MILLION TONS PER YEAR EVENTUALLY REACH THE
LAND IN ONE FORM OR ANOTHER.
AS THE ABOVE DISCUSSION INDICATES, THERE IS EXTENSIVE USE OF THE
LAND FOR TREATMENT OF MUNICIPAL WASTEWATERS IN THE UNITED STATES.
NUMEROUS INSTALLATIONS ALSO EXIST IN OTHER COUNTRIES INCLUDING GREAT
BRITAIN, GERMANY, FRANCE, AND AUSTRALIA. WHILE NO HARD, SUPPORTIVE
DATA EXIST, IT CAN READILY BE ASSUMED THAT MOST COUNTRIES UTILIZE THE
LAND EXTENSIVELY FOR DISPOSAL OF THE SOLIDS BY-PRODUCTS OF TREATMENT V/ORKS.
UNFORTUNATELY, ALTHOUGH MANY OF THESE SYSTEMS HAVE BEEN IN
EXISTENCE FOR MANY YEARS, THERE IS RELATIVELY LITTLE RELIABLE DATA
AVAILABLE ON SYSTEM PERFORMANCE. THE PHYSICAL, CHEMICAL, AND BIOLOGICAL
SYSTEMS ACTIVE AND PERFORMING THE TREATMENT ROLE IN LAND TREATMENT ARE
LARGELY UNDEFINED. UNDEFINED IN THIS INSTANCE MEANS THAT THE SYSTEMS ARE
NOT UNDERSTOOD SUFFICIENTLY WELL THAT PREDICTIONS OF PERFORMANCE OF A
GIVEN DESIGN ARE NOT AS RELIABLE AS SIMILAR PREDICTIONS FOR "CONVENTIONAL"
TREATMENT WORKS. MODIFICATIONS SUCH AS CONTOURING AND UNDERDRAINING CAN
BE MADE TO THE LAND TO RECEIVE EFFLUENTS, BUT THE TOTAL TREATMENT SYSTEM
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IS PRIMARILY AN UNCONTROLLED NATURAL FUNCTION TYPICAL ONLY OF THE
SPECIFIED SITE UNDER CONSIDERATION. THIS IS QUITE UNLIKE CONVENTIONAL
PROCESSES WHICH, IF BIOLOGICAL PROCESSES ARE EMPLOYED, PROVIDE A CONTROLLED
ENVIRONMENT FOR ENCOURAGEMENT OF OTHERWISE NATURAL PROCESSES.
GROWTH OF LAND TREATMENT SYSTEMS IN THE UNITED STATES WILL TAKE
PLACE IN A PRODUCTIVE, ENVIRONMENTALLY ACCEPTABLE MANNER ONLY IF ENOUGH
INFORMATION AND KNOWLEDGE OF HOW THE LAND FUNCTIONS AS A WASTEWATER
TREATMENT SYSTEM IS OBTAINED.
THE OFFICE OF RESEARCH AND MONITORING, EPA, HAS AN ACTIVE RESEARCH
PROGRAM DESIGNED TO DEVELOP AND DEMONSTRATE THIS KNOWLEDGE. WE FEEL THIS
INFORMATION MUST BE OF A DEPTH AND QUALITY THAT WILL PERMIT SOUND DESIGN AND
RELIABLE PERFORMANCE PREDICTION OF LAND TREATMENT SYSTEMS.
I WOULD LIKE TO NOTE THAT A PORTION OF THE RESEARCH, DEVELOPMENT, AND
DEMONSTRATION PROGRAMS OF EPA AND ITS PREDECESSOR AGENCIES HAS BEEN DEVOTED
TO LAND TREATMENT FOR BOTH MUNICIPAL AND INDUSTRIAL WASTEWATER FOR 15 YEARS.
HOWEVER, UNTIL RECENTLY, THIS EFFORT HAS BEEN LOW KEY.
APPROXIMATELY 14% OF THE TOTAL BUDGET FOR FISCAL 1974 FOR THE MUNICIPAL
TECHNOLOGY RESEARCH PROGRAM IS PLANNED FOR DEVELOPMENT OF LAND TREATMENT
TECHNOLOGY. (THIS INCLUDES SLUDGE APPLICATION TO THE LAND.) THIS AMOUNTS
TO APPROXIMATELY $1.2 MILLION AND IS EQUIVALENT TO THE FUNDS AVAILABLE IN
THE FY 1973 PROGRAM.
I WILL NOT GO INTO DETAIL ON THE VARIOUS RESEARCH ACTIVITIES SINCE
MY ASSOCIATE, DR. ROBERT DEAN, HAS ALREADY SPOKEN TO THE LAND APPLICATION
OF SLUDGES AND ANOTHER ASSOCIATE, DR. WILLIAM DUFFER, WILL SPEAK LATER
TODAY ON EFFLUENT LAND APPLICATION RESEARCH ACTIVITIES. BUT, BRIEFLY I
WILL SURFACE SOME OF THE PHILOSOPHY BEHIND THE PROGRAM.
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IN GENERAL, V/E FEEL THAT A PRIME REQUISITE FOR ANY WASTE TREATMENT
TECHNOLOGY IS THAT A POLLUTANT FROM ONE MEDIUM BE PREVENTED FROM CREATING
POLLUTION IN ANOTHER MEDIUM. WE HAVE TAKEN THIS APPROACH IN OUR DEVELOPMENT
OF TECHNOLOGY FOR ADVANCED WASTE TREATMENT SYSTEMS AND WE FEEL THIS APPROACH
IS ALSO APPLICABLE TO LAND TREATMENT TECHNOLOGY.
V/E DO NOT FEEL THAT LAND TREATMENT IS THE PANACEA, BUT IT IS AN
ALTERNATIVE TO ADVANCED WASTE TREATMENT. THERE ARE MANY UNRESOLVED ISSUES
IN LAND TREATMENT TECHNOLOGY THAT CAUSES SOME HESITATION ON OUR PART, THAT
IS, EPA, TO COMPLETELY ENDORSE CURRENT PRACTICES.
PERHAPS THE PARAMOUNT PROBLEM IS THE FATE AND EFFECT OF PATHOGENS AND
THE POSSIBILITY OF THE TRANSMISSION OF HUMAN AND ANIMAL DISEASE AND INFECTIONS.
QUESTIONS HAVE BEEN RAISED CONCERNING POTENTIAL HAZARDS FROM THE CONSUMPTION
BY HUMANS AND ANIMALS OF CROPS GROWN ON SOIL TREATED WITH SEWAGE SLUDGE OR
EFFLUENT. THIS PROBLEM IS PERHAPS OF MORE CONCERN WHEN CONSIDERING THE
LATTER PROCEDURE OR WHEN RAW SLUDGE IS APPLIED TO THE LAND. WE FEEL THAT
THERE IS LESS CONCERN FOR DISEASE TRANSMISSION WHEN APPLYING TO LAND DIGESTED
SEWAGE SLUDGE. HOWEVER, IN ANY CASE, CAUTION IS NECESSARY.
QUESTIONS HAVE BEEN RAISED CONCERNING TOXIC SUBSTANCES AND NON TOXIC
ORGANIC WASTE MATERIALS OCCURRING AS CONSTITUENTS OF SLUDGE OR LIQUID EFFLUENT.
THESE QUESTIONS ARISE AS DISCHARGES FROM INDUSTRIAL PROCESSES SUCH AS THE
CHEMICAL PRODUCTION OF TEXTILES, PLASTICS, PHARMACEUTICALS, DETERGENTS
AND PESTICIDES ENTER THE DOMESTIC SANITARY COLLECTION SYSTEM. WE DO NOT
KNOW WITH CERTAINTY THE EFFECTS, SHORT AND LONG RANGE, OF THESE MATERIALS
WHEN PLACED ON THE LAND. THERE ARE OTHER QUESTIONS BEING RAISED, HOWEVER,
I WILL NOT GO INTO THESE FOR SHORTNESS OF TIME.
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THE EPA IN ITS RESEARCH PROGRAM IS ATTEMPTING TO ANSWER THE QUESTIONS
RAISED IN THE PRECEEDING DISCUSSION AND OTHERS. WE ANTICIPATE THAT
GUIDELINES FOR LAND APPLICATION OF EFFLUENTS AND SLUDGES WILL BE GENERATED
IN THE NEAR FUTURE. THESE GUIDELINES WILL BE BASED, OF COURSE, ON THE
CURRENT STATE OF THE ART, AND, THEREFORE, SHOULD BE EVALUATED VERY CAREFULLY
FOR EACH PROPOSED LAND TREATMENT SYSTEM.
THE EPA HAS INITIATED A COMBINED EPA-USDA-NATIONAL LAND GRANT
UNIVERSITY COORDINATING COMMITTEE FOR ENVIRONMENTAL QUALITY. THIS
COMMITTEE IS SPONSORING FOUR AD-HOC SUBCOMMITTEES, ONE OF WHICH IS ON
THE SUBJECT OF RECYCLING URBAN AND INDUSTRIAL EFFLUENTS AND SLUDGES TO
THE LAND.
THIS AD-HOC SUBCOMMITTEE HAS THE PRINCIPAL OBJECTIVE OF DEVELOPING
AND IMPLEMENTING INSTITUTIONAL PROCEDURES TO EFFECTIVELY USE THE RESOURCES
AVAILABLE WITHIN THE EPA-USDA-UNIVERSITY STRUCTURES FOR A COOPERATIVE AND
COORDINATED RESEARCH, DEVELOPMENT, AND DEMONSTRATION PROGRAM. IT HAS
BECOME MORE APPARENT AS THIS COMMITTEE WORKS TOGETHER, THAT IT IS
ESSENTIAL TO HAVE A MULTI-DISCIPLINE AND MULTI-ORGANIZATIONAL APPROACH
FOR THE IDENTIFICATION OF THE SLUDGE PROBLEM AND IDENTIFICATION OF THE
ALTERNATIVES AVAILABLE TO SOLVE THE PROBLEM. A PROBABLE OUTCOME OF THIS
WORKING COMMITTEE WILL BE A REDIRECTION OF RESEARCH EFFORT FOR EPA-USDA-
UNIVERSITIES IN ORDER TO AVOID COSTLY DUPLICATION OF RESEARCH PROGRAMS.
THE AD-HOC SUBCOMMITTEE IS PLANNING A FOUR DAY CONFERENCE WORKSHOP
TO BE HELD IN EARLY JULY. THE PURPOSE OF THIS CONFERENCE IS TO IDENTIFY
WHAT IS KNOWN ABOUT SLUDGE AND LIQUID EFFLUENT APPLICATION TO THE LAND,
AND WHAT RESEARCH IS NEEDED FOR SUCCESSFUL APPLICATION OF WASTES TO THE
LAND FROM ECONOMIC, ENGINEERING, HEALTH, AND ESTHETIC POINTS OF VIEW.
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HOPEFULLY, THIS CONFERENCE WORKSHOP WILL PROVIDE A WORKING BASE
FOR AN INTENSE COOPERATIVE EFFORT IN THE FEDERAL-UNIVERSITY COMMUNITY
THAT WILL IMPACT THE PUBLIC COMMUNITY BY HELPING TO SOLVE AN ACUTE
ENVIRONMENTAL PROBLEM.
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"LAND TREATMENT AND ENVIRONMENTAL ALTERNATIVES"
by
Barbara Reid
Project on Clean Water Natural Resources Defense Council
I. Introduction: The Water Pollution Control Problem
Our rivers and lakes are clogged with filth. Many are in the throes
of ecological death. Instead of serving as national assets, our waterways
have become liabilities, acting as transmitters of viruses and heavy
metals, as sluiceways for industrial and municipal wastes. Episodes like
the following are commonplace:
—On March 30, 1971, the U.S. Geological Survey found signi-
ficant concentrations of seven toxic metals (mercury, arsenic,
cadmium, lead, chromium, cobalt, and zinc) in many of the
nation's streams and lakes.
—In April, 1972 a study of "properly treated" drinking water
in Billerica and Lawrence, Massachusetts found the presence
of viruses capable of causing respiratory and heart disease,
nonbacterial meningitis, muscular paralysis, hepatitis, diar-
rhea, vomiting and flu.
—In our nation's capital, the Potomac River is lined with
signs reading, "Danger—Polluted Water" and instructions
warning anyone coming into contact with the water to get a
tetanus shot. Bacterial counts have consistently ranged
200% to 3400% above the recommended U.S. Public Health Service
standards for at least the last five years.
—In the summer of 1972 the coastal waters of Massachusetts
and New England were hit by an outbreak of "red tide" which
shut down the clam and oyster industry, causing the loss of
millions of dollars.
Examples like these demonstrate the failure of government at every
level to control the dumping of wastes into our national waterways. The
effort to control pollution has been haphazard. Laws have been weak and
tepidly enforced, promoting a don't-do-more-than-necessary attitude among
decision-makers.
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The recently passed Federal Water Pollution Control Act Amendments
of 1972 (Public Law 92-500), however, promise a new beginning. Through
this legislation, Congress has discarded the philosophy that waterways
should "assimilate" pollution up to their natural capacity. Instead, it
has set a national goal of zero discharge of pollution by 1985; interim
deadlines for industrial and municipal sources of pollution should force
progress toward that goal.
The state and federal fight against pollution has not only been
hampered by poor laws, however—it has also been weakened by a lack of
technological choices. Few industries recycle their wastewater. Many of
them discharge into municipal systems that are already over burdened with
human sewage and street runoff. For their part, municipalities have
fallen back on a 50-year-old system of primary-secondary treatment, which
screens the effluent and reduces its biological demand through bacterial
decomposition. Nutrients (such as nitrogen and phosphorus), most heavy
metals and many other chemicals cannot be removed by such systems—and no
primary-secondary plant can achieve the high goals for pollution control
that the new law sets for the 1980's.
Recent chemical extensions of primary-secondary treatment into a
new tertiary stage ("advanced biological" and "physical-chemical" systems)
offer some promise of cleaner municipal effluents. Such chemical systems
have major drawbacks, however. They are expensive. They consume large
quantities of fuel, electric power and chemicals. And they produce vast
amounts of chemical sludge which must be disposed of by land filling or
by burning. Above all, chemical innovations such as advanced biological
(sometimes called Advanced Waste Treatment or AWT) still handle sewage
nutrients as noxious substances to be disposed or rather than as resources
to be used.
There is an ecological alternative to the wasteful strategies of the
past and the chemical options described above. This alternative is the
confinement and purification of wastewater on the land. By returning all
human and most industrial wastes to the land, this system uses the natural
processes of time, sun, wind, vegetative growth and the physical and
chemical makeup of soils to purify wastewater. As Senator Edmund S. Muskie
(D-Maine) explained while submitting the Federal Water Pollution Control
Act amendments to the Senate in November, 1971: "These policies ... simply
mean that streams and rivers are no longer to be considered part of the
waste treatment process."
The land treatment alternative can accommodate solid waste disposal
sites, greenbelts, and other elements in a broad resource management pro-
gram for any community. It is preeminently an ecological system. Yet it
has been generally overlooked by most state and federal water pollution
control agencies and, indeed, by most environmental groups.
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One reason the land treatment alternative has received so little
attention is that water pollution control has been vested in the sanitary
engineering profession rather than in the water resources management
discipline. The result has been a heavy emphasis on disposal techniques
instead of recycling and reuse techniques.
A large land treatment system, scheduled to begin operations in
Muskegon County, Michigan in the spring of 1973, should spark national
interest in the new alternative. Based on engineering bids and other
preliminary data, the Muskegon system will cost less to build and operate
than any comparable chemical treatment plant. It also dovetails the
waste treatment, greenbelt and solid waste management functions on one
site.
In light of the new national goal of "zero discharge of pollutants",
I urge you to survey the requirements for water pollution control in your
community with an eye toward future needs and federal standards. Land
disposal is a viable, natural alternative for many large and small areas—
an alternative that has gone largely unnoticed in our rush to find a
technological "fix" for our environmental ills.
II. Land Treatment: State-of-the-Art
Land treatment is a complex system which must be carefully planned
and engineered to assure that the rate of application of treated wastewater
conforms to local climate, i.e., soil, vegetative and geologic conditions.
If this is not done, soil systems may be overloaded and desired levels
of treatment may not be achieved. In general discussions of land treatment,
questions have been raised about four major considerations: 1) performance;
2) costs, in terms of capital, operations, outlays, and returns or profits;
3) political acceptance and 4) public health.
Performance
The question of performance concerns the ability of the land to purify
wastewater. Naturally, one factor determining this ability is the nature
of the effluent. Some land recycling systems may have to cope with an ovei-
abundance of phosphates or heavy metals that could, with time, build up in
the soil. Heavy metals (now being dumped into our streams and rivers
primarily by industry) would have to be carefully diluted and spread over
wide areas of land. Without careful monitoring and control, they could
slowly build up in the soil and become toxic to some plants. But monitoring
of soil conditions would anticipate any toxicity problems which could be
met in a number of ways, including industrial pretreatment.
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Several studies have been made of the quality of reclaimed water
to be expected from land treatment systems. Two of these were performed
for the U. S. Army Corps of Engineers. The first, "Wastewater Management
by Disposal on the Land", was carried out by the Cold Regions Research
and Engineering Laboratory in Hanover, New Hampshire; the second study
was conducted by an interdisciplinary team at the University of Washington
in Seattle. According to these studies and other laboratory tests, the
final effluent of a well-managed land recycling system should have the
following characteristics:
Parameter Effluent Quality % Removal
(in parts per
million—ppm)
Chemical Oxygen Demand 6
Biological Oxygen Demand (5 day) 2 99
Suspended Solids c 0.0 99+
Soluble Phosphorus c 0.01 99
Nitrogen (in organic form) c 0.0
Nitrogen (in ammonia form) c 0.0
Nitrogen (in nitrate form) 2
Total Nitrogen 80-90
Oils and Greases c 0.0
Phenols c 0.0
Viruses and Bacteria c 0.0 99+
Trace Metals c 0.0
Boron c 0.0
Arsenic c 0.0
Cyanide c 0.0
Heavy Metals 99
Organic Compounds 99
(some of these categories overlap)
The effluent quality shown here is higher than the recommended U. S. Public
Health Service drinking water quality standards.
The above standards can be achieved by a properly designed system.
Some of the health concerns that the public-at-large has expressed stem
from the possibility that a land treatment system might not be properly
constructed; engineers should, in a sense, translate these concerns into
design parameters. Among the necessary parameters are the infiltration of
the soil, the ability of crops to remove nitrogen and phosphorus, the
depth of ground water, the geology of the area, the nature of the effluent
after pretreatment, and the ability of any particular soild to achieve
high levels of wastewater treatment.
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Designers of land treatment systems must also study climatic and
plant cover conditions. The length of the growing season may be important
(although wastewater has been applied successfully to forest land during
the winter months). As an alternative to forest irrigation, the treated
wastewater may be stored during the winters. Large storage lagoons have
been built for the Muskegon project to hold the effluent (plus rainfall
and runoff) during periods when it cannot be absorbed by the soil. The
need for winter storage will vary with each community according to its
climate and length of growing season.
Costs
While there is continuing debate over the costs of both land treat-
ment and other tertiary systems, certain empirical evidence is already
available. This preliminary information indicates a fovorable economic
position for land treatment.
As noted earlier, the costs for construction, land and family reloca-
tion in Muskegon County total only 83
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2) Application rates either regulated by state law or by environ-
mental considerations.
3) The physical method of irrigation; and
4) Topography (rarely is irrigation practiced on greater than 15%
slopes without some form of terracing).
The cost of a land treatment system will also depend on whether the
irrigation land is purchased outright, leased, or contracted. But it is
important to note that the use of the land for agriculture will not be
changed—merely the manner in which the crops are irrigated and fertilized.
In a time of rapid disappearance of rural land due to uncontrolled suburban
development, irrigation sites should offer invaluable greenbelts and new
opportunities to control metropolitan land use patterns.
There is a little historical experience from which we calculate
operating costs of alnd treatment systems. The estimated cost of Muskegon's
first year of operation now stands at 9c per thousand gallons of treated
sewage. This figure should be compared with the 30
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A fundamental fact is the need for substantial tracts of open space
in a land treatment system. The actual amount of such land will vary ac-
cording to the length of the growing season, and the amount of winter
storage required. In Muskegon County, 230 acres of land per million
gallons per day of wastewater will be required. While at Penn State
University 130 acres are needed. Using an average for estimates on a
national scale of 180 acres per million gallons of wastewater per day,
the amount of land required for national land treatment is estimated to
be 7.5 million acres. This corresponds to 6% of the land area of the
state of Texas and about 1% of land on which the 59 major agricultural
crops are grown in this nation today. The current land use of this
acreage will not change. Only the method of fertilization and irrigation
would be altered by the !=and treatment approach.
In the event of family relocations, which may be inevitable with any
large public works project, reimbursement is available through the Uniform
Relocation Assistance and Real Property Acquisition Policies Act of 1970.
Such assistance was very helpful in the Muskegon land acquisition program
which relocated 195 families.
Public Health
Public concerns about the potential health effects of land treatment
systems have been voiced in debates over sewage treatment for some time.
From a communicable disease standpoint, however, a study by a re-
searcher at the Department of Communicable Diseases, Hahnemann Medical
College, Philadelphia, has concluded that "land disposal is far less
hazardous than disposal into rivers and streams". The researcher, Dr.
Melvin A. Benarde has said, "The actual hazard, or petential hazard, to a
community's health would be realted to the degree of treatment or the
ultimate quality of the reused waste". In other words, the higher the
degree of treatment, the safer the community's health.
It is important to remember that an integral part of a well—designed
land treatment system is the pretreatment of wastewater before land ap-
plication. This means the equivalent of primary and secondary treatment
(including chlorination for disinfection). Thus, the effluent at the time
of spray irrigation should meet a standard of water quality suitable for
recreational purposes.
Many state and federal agencies have begun to establish guidelines
to insure proper health protection for all land treatment systems. Included
in the U.S. Surgeon General's guidelines are the following considerations:
pretreatment, non-potable identification, vector (disease carrier) control,
surveillance, aerosol control, and access limitation (buffer zones).
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Since disinfected secondary treated effluent is being sprayed on
the land, the possibility of contaminating the air with air-borne viruses
is very small. However, to further minimize any possibility of contamina-
tion through aerosol drfit, irrigation nozzles may be directed downward.
Their pressure may also be kept low to insure large droplets. Irrigation
need not take place during times of high winds, rainfall or low tempera-
tures—conditions generally associated with aerosol drift.
On further precautionary measure is the provision of buffer strips
around spray sites to prevent any accidental drift and any direct contact
with the irrigation spray.
Ironically, the success stories about land treatment heretofore have
come from systems which have utilized none of the above precautions; most
of them have applied raw sewage to land producing crops that are fed directly
to livestock and/or to people. Melbourne, Australia, and Paris, France,
have long used irrigation projects of this type. No health problems have
been attributed to either of these systems.
For several years the U. S. Army has practiced spray irrigation of
a Colorado golf course, using wastewater originating from a large hospital
specializing in tuberculosis treatment. Data accumulated since 1953 in-
dicate that no health hazard can be detected from spray irrigation of the
treated wastewater even though the tuberculosis-causing bacteria can be
found in the untreated water.
III. A Final Word
The effects of the 1972 Water Pollution Control Act will soon be felt
in every community. You will be asked to respond to three basic policy
changes the legislation makes in the nation's water quality program. These
are, first, the replacement of a waste disposal strategy with a management-
and-use strategy; second, the transformation of an essentially single-
purpose water quality program into a multipurpose resource program; third,
the change from a federal subsidy program into a federal investment program
that has the potential to produce revenue. The irrigated crops, solid waste
disposal sites, and use of land treatment storage lagoons for industrial
cooling can all generate income for communities that choose the land re-
cycling alternative. This income is theirs to finance other environmental
improvements.
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NEW YORK STATE'S
VIEW OF LAND DISPOSAL
by
Frank O. Bogedain, P. E.
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INTRODUCTION
The disposal of waste-water to the land is not a new concept either in
the United States or more particularly in my State of concern - New York
State. Koelzer (ref. 1) points out that the method is an old one predating
secondary plants. Called "sewage farms" and empirically developed, the
method is variably successful. Melbourne (ref. 2), Australia reports that
the Board of Works Farm at Werribee, operational since 1892, it was
successfully handling a median daily flow of approximately 100 MGD in 1969.
It should also be noted that the present advocation of land disposal is
engendered, at least in part, by Sec. 101, subd. (1) of PL 92-500 which states:
". . . it is the national goal that the discharge of pollutants into
the navigable waters be eliminated by 1985;"
In New York State, approximately 3,800 MGD of wastewater from
municipal and industrial sources are now generated. This volume is almost
equivalent to twice the average low freshwater flow of the Hudson River and
would require large land areas and attendant costs (ref. 3) if uniformly applied.
The 'zero discharge' advocates have pointed to land disposal as the new
panacea. However, if land disposal is examined objectively, it must be
concluded that it is neither new nor a panacea.
MUNICIPAL SYSTEMS
As far as the author is able to discern the first municipal plant to dispose
of waste effluent to the land is the Lake George Village plant of which you'll
hear more of later in the program. It has been operating in this mode since
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1936. However note should be taken that this plant and the other municipal
plants listed in Table I do not employ Spray Irrigation (SI), Overland Runoff (OR)
but use Rapid Infiltration (RI) in the form of tile fields, leaching pits or non-
underdrained, intermittently-dosed sand filters.
The proportion of communal plants utilizing land disposal in New York
State is small. Of 477 municipal plants designed to handle a total of 2, 430
MGD, 24 plants are designed to process 9. 5 MOD for ground discharge.
In reviewing TABLE I, it is apparent that these systems serve very
small comparatively isolated communities or are located on Long Island
where a trend to groundwaters recharge is distinct.
INDUSTRIAL SYSTEMS
In similar fashion to the municipal picture in New York the proportion
of industrial waste disposal to the ground has been minimal. Of 284
industrial systems designed to process 437 MGD, 12 plants are designed to
dispose of 5. 2 MGD to the land by spray irrigation.
All of our regulatory agency experience comes from these 12 systems.
Indeed much has been learned on a first hand basis. TABLE II summarizes
these 12 systems.
Spray irrigation as a viable method of industrial waste treatment
evolved in New York primarily because of unique circumstances surrounding
the food processing industry of which all 12 systems serve. This industry
is primarily seasonal with wastewater generation occurring during periods
of low stream flow, warm temperatures and production facilities primarily
153
-------
located at the higher end of watersheds where streams are ephemeral.
Such locations being rural in nature, land is readily available. These
locational factors demand high levels of treatment efficiency for short periods
of time if discharge to a surface watercourse can be considered. Biological
treatment is virtually precluded.
INDIVIDUAL SYSTEMS
In 1970, it was estimated that 14. 6 million people in New York State were
served by community sewerage. This represents approximately 80% of the
resident population of 18. 3 million persons. The remainder - 20%, or 3. 6
million persons - are served by individual home disposal systems of the septic
tank/tile field (or leaching pit) variety. Thus land disposal plays an important
role at the family level of social development in an agrarian setting.
RESEARCH
In the area of Land Disposal, New York's research effort has been
directed to the following:
1) A literature search, which constitutes 130 references.
2) Specific investigation for determining phosphorus adsorption
capacities of soils, including methodology, with particular reference
to the design of septic tank/percolation systems for lake watershed
protection. In this regard an application has been made to EPA for
a Research and Development Grant pursuant to Sec. 105 of PL 92-500.
154
-------
In regard to the latter project, our concern is not only related to
developing a groundwater recharge method which removes BOD, solids,
bacteria and phosphorus but also is part of our continuing research effort
into cause, effect, prevention and control of lake eutrophication.
REGULATORY AGENCY ATTITUDE
Contemporary writings (ref. 4, 5, 6) claim many advantages to Land
Disposal when compared to secondary treatment:
a) Lower capital and operating costs;
b) Upgrading of marginal agricultural land and concomitant benefits;
c) Reduced sludge disposal problems;
d) Nutrient recycling;
e) High removal of viruses, toxic materials, BOD, Solids, etc. ;
f) Groundwater recharge;
g) Protection of surface waters.
to name a few.
Counter arguments are:
a. Social and economic impact of relocating farm families;
b. Availability of suitable land;
c. Buildup of toxic and solid material which may be detrimental
to the project and environment;
155
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d. Costs picture difficult to assess because of lack of actual
operating experience for large scale systems;
e. Transmission costs to land disposal areas;
f. Economic impact of taking land out of production and removing such
land from the tax rolls;
g. Acceptability for meeting the 'zero discharge1 imperative;
h. Effect on groundwaters.
Presently we regard 'Land Disposal' as an acceptable alternate to
disposal of wastewater to surface waters, with the inference being that
'land disposal1 is a catch-all categorization for methods which are essentially
groundwater disposal and/or recharge methods.
For municipal application, rather complete engineering evaluation is
required of any feasible alternative especially because of the fact that the
State of New York, along with EPA, participates in such projects through
the construction grant mechanism. Additionally New York State can provide
up to 33-1/3% of annual operating and maintenance grants. Such an economic
evaluation derives from the impelling need to achieve the most effective
treatment per unit cost.
What about guidelines? At present New York has no formally adopted
design guidelines published, but is developing them and will be in a future
paper. Pennsylvania's manual on spray irrigation (ref. 7) is a valuable
effort and is to be commended.
156
-------
Our own surveys have shown that several points are key to attaining
a successfully operating system. These are:
1) Failure to rotate and maintain fields;
2) Spray nozzles clogged with stones causing either nonuniform
application with localized flooding;
3) No operator assigned to manage the system;
4) Unanticipated wastes of high strength allowed to enter the
disposal system;
5) Lack of equalization and detention;
6) Excessive pH variation 'shocking' crop cover;
7) Extremely high application rates causing runoff.
CONCLUSIONS
This paper has attempted to present the relative position of Land
Disposal as regarded by the State of New York.
Accordingly it is shown that -
1) Land Disposal is an established method ofwaste disposal but is little used,
2) Numerous problems can be encountered with this approach, as well as
with any other system.
3) Competent planning, design, construction and deration are needed
stages which cannot be omitted.
4) The many pro and con arguments can only be answered by detailed
studies of increasingly larger installations.
157
-------
REFERENCES
1. Koelzar, Victor K. , "Land Disposal of Sewage Effluent", April, 1972,
National Water Commission, Arlington, Va.
2. Anon, "Waste into Wealth", June, 1969. Melbourne and Metropolitan
Board of Works.
3. Metzler, Dwight F. and Bogedain, Frank O. , "The Cost of Water Quality
Goals", National Symposium on Costs of Water Pollution Control, April
1972, University of North Carolina, Raleigh, N. C.
4. McGauhey, P. H. and Krone, R. B. , "Soil Mantle as Wastewater Treat-
ment System", SERL Report No. 67-11, Univ. of Calif. , Berkeley, 1967.
5. Bailey, G. W. , "Role of Soils and Sediment in Water Pollution Control"
Part I, U. S. Dept. of the Interior, Southeast Water Laboratory,
Mar. 1968.
6. Reed, S,, ct al, "Waste-water Management by Disposal on the Land",
Special Report No. 171, U.S. Army Corps of Engineers, Hanover, New
Hampshire, May 1972.
7. Anon, "Spray Irrigation Manual", Pub. No. 31, Bureau of Water Quality
Management, 1972 Edition, Pennsylvania Deparf nent of Environmental
Resources, Harrisburg, Pa.
158
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ABOUT THE AUTHOR
FRANK O. BOGEDAIN is Director of the Bureau of Municipal Wastes,
New York State Department of Environmental Conservation. He received
both his Bachelor's and Master's Degrees of Civil Engineering (Sanitary
Engineering Major) from New York University, and is licensed to practice
engineering in the States of New York and Pennsylvania. He has written
and co-authored several papers in the field of water pollution control, and
is honorably mentioned in several others. He is a certified Grade 1A
Sewage Treatment Plant Operator in New York State.
159
-------
TABLE I
MUNICIPAL WASTEWATER TREATMENT
PLANTS DISCHARGING TO LAND
Name/Loc at ion
REGION 1 - STONY BROOK
Farmingdale Sanitarium
Oyster Bay (T), Nassau County
Mitchell Field
/Hempstead (T), Nassau County
Meadowbrook Hospital
Hempstead (T), Nassau County
Scavenger Plant
Oyster Bay (T), Nassau County
Chemical/Sand Filter
Stratmore at Coram (Private
Disposal Corp)
Brookhaven (T), Suffolk County
Stratmore at Stony Brook
Brookhaven (T), Suffolk County
Holbrook Sanitary District
Brookhaven (T), Suffolk County
Stratmore at Huntington
Huntington (T), Suffolk County
Scavenger Plant
Babylon (T), Suffolk County
Manorville Scavenger Plant
Brookhaven (T), Suffolk County
REGION 2 - NEW YORK CITY
Treatment
Imhoff Tank
Sand Filter
Primary Settling
Sand Filter
Trickling Filter
Cesspool
Cesspool
Contact Stabilization
Cesspool
Contact Stabilization
Sand Filter
Trickling Filter
Cess pool
Extended Aeration
Sand Filter
Chemical-Physical
Sand Filter
Extended Aeration
Sand Filter
None
MGD Design MGD Actual
0.120
1.200
0.900
0. 052
0. 063
0. 535
0.663
0. 035
1.360
0. 360
0.720
0.236
1.000
0.225
0.289
0.053
0.162
0.107
0.050
160
-------
TABLE I (Continued)
Name /Location
REGION 3- NEW PALTZ
Chichester Hamlet
Shandakin (T), Ulster County
(New York City Plant)
REGION 4 - ALBANY
Treatment
Septic Tank/Tile Field
WilHamsburg (Private)
Guilderland (T), Albany County Septic Tank/Tile Field
REGION 5 - RAY BROOK
MGD Design MGD Actual
0. 060
0. 010
0. 060
Clifton Knolls (Private)
Clifton Park (T), Saratoga Co.
Clifton Gardens (Private)
Clifton Park (T), SaratogaC o.
Geyser Crest (Private)
Saratoga Springs (C)', Saratoga Co.
Round Lake Assoc.
(Private Owner)
Round Lake (V), Saratoga Co.
Bolton Sanitary District
Bolton (T), Warren County
Lake George Village
Lake George (V), Warren County
Reservoir Park San. District
Queensbury (T), Warren County
REGION 6 - WATERTOWN
Contact Stabilization
Sand Filter 0. 300
Extended Aeration
Sand Filter 0. 800
Extended Aeration
Sand Filter 0. 185
Septic Tank/Tile Field 0.004
Trickling Filter
Sand Filter 0. 300
Trickling Filter
Sand Filter 1. 745
Septic Tank/Seepage Pit 0. 012
0.160
0. 045
0.1Z4
0. 012
0.120
0.450
Glenfield Sanitary District
Martinsburg (T), Lewis County Septic Tank/Tile Field
0. 040
161
-------
TABLE I (Continued)
Name/Location
REGION 7 - SYRACUSE
Fenton Sanitary District No. 1
Fenton (T), Broome County
Ruhanah Sanitary District
Oncndaga (T), Onondaga County
REGION 8 - AVON
REGION 9 - BUFFALO
Treatment
MGD Design MGD Actual
Septic Tank/Cesspool
Septic Tank/Cesspool
None
Lewiston Estates Sanitary District
Lewiston (T), Niagara County Septic Tank/Cesspool
Idlewood Sanitary District No. 13
Hamburg (T), Erie County Septic Tank/Sand Filter
0. 014
0.022
0. 022
0.010
0. 034
0. 007
162
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TABLE II
INDUSTRIAL WASTEWATER TREATMENT PLANTS DISCHARGING TO LAND
Company
Curtice Burns
Sodus (T),
Wayne County
Curtice Burns
Bergen (V),
Genesee Co.
Curtice Burns
Leicester (V),
Livingston Co.
Corns toe k
Greenwood
Waterloo (V),
Seneca Co.
Gro-Pack
Eden (T),
Erie Co,
Libby, McNeil
& Libby
Geneva (T),
)ntario County
Design
Flow
MGD
0. 644
1.0
1.85
0.4
0.17
0.5
Application
Rate*
(Max. )
2. 5 in/day
1.15 in/hr
0. 25 in/hr
0. 6 in /day
0. 32 in/day
0. 32 in/day
Soil
Williamson
Silt Loam
Hilton Loam
Cazenovia
Silt Loam
Ontario
Silt Loam
Gravel,
Silt
Schoharie
C lay Loam
Coyer
Crop
Reed
Canary
Grass
Reoc'
Canary
Grass
Reed
Canary
Grass
Blue
Grass
Rye
Grass
Product
Cherries
Beets
Apples
Beans
Pea
Corn
Beans
Carrots
Corn
Peas
Beets
Ca rrots
Beets
Red
Cabbage
Beans
Peas
Green
Beans
Saue r -
kraut
Pretreat-
ment
Lagoons
PH
Adjust-
ment
PH
Adjust-
ment
Lagoons
Lagoons
Lagoons
No. of
Sprin-
lers
200
310
75
60
80
Spray
Area
12.500
ft2
0.23
acre
0.13
acre
0.3
acre
7850
ft2
Field
Schedules**
12 hr/day
July-Dec
12 hr/day
June /Dec.
18 hr/day
July -Nov.
Aug-Dec.
18 hr/day
July-Sept.
16 hr/day
Jan-Dec.
Spray
Schedule
Use/Rest
1/4
12 hr/60 hr
1/4
1/4
163
-------
TABLE II (Continued) Industrial Wastewater Treatment Plants Discharging to Land
C ompany
Sodus Fruit
Farm
Sodus (T),
Wayne County
Deltown
Food
Delhi (T),
Delaware Co.
Cuba Cheese
&: Trading Co.
Cuba (T),
Alleeany Co.
Lasaponara
6t Son
Goshen (T),
Orange Co.
Friendship
Dairy
Friendship (T),
Allegany Co.
Desig
Flow
MGD
0.1
0.3
0. 025
0. 006
0.16
n Application
Rate*
(Max. )
1. 3 in/ day
3. 8 in/ day
0.25 in/hr
1. 37 in/day
0. 56 in/day
2 fields
1. 2 in/day
Soil
Williamson
Silt Loam
Chenango
Gravel
Loam,
Gravel
Gravel
Silt
Coyer
Crop
Japan-
ese
Miller
Red Toj
Red
Fescue
Reed
Canary
Grass
Canary
Grass
Timothy
&
Meadow
Grass
Product
Apples
Cherries
Prunes
« Milk
Cheese
Cheese
Milk
Cheese
Butter
Cheese
Sour
Cream
Pretreat-
ment
Lagoons
Equali-
zation
Screen-
ing
Equali-
zation
Tank
Lagoons
No. of
Sprin-
klers
20
20
5
15
Spray
Area
29
acre
total
31,400
ft2
0.09
acre
9,850
ft2
5,000
ft2
Field
Schedules**
6 hr/day
Jan-Dec.
9 hr/day
Jan-Dec.
8 hr/day
Jan-Dec.
12 hr/day
Jan-Dec.
Spray
Schedule
Use/Rest
1/8
1/4
1/4
1/2
1/6
* Sample calculations of the average application rate in in. /hr.
* Except for Deltown Foods spraying occurs only during daylight hours.
164
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Municipal Effluent Characteristics
by
Joseph V. Hunter *
The effect that the land disposal of municipal treatment
plant effluents will have on soil permeability, ground water
quality, cropping, subsequent land reuse, etc., will to a
large extent be determined by the biological, physical and
chemical characteristics of the effluents applied. Assuming
a minimum of secondary treatment and that biological quality
problems can be handled by suitable effluent disinfection,
this paper is mainly concerned with the physical and chemical
characteristics of secondary effluents.
Physical Characteristics
Even casual observation of municipal secondary effluents
indicates the presence of other than soluble materials. Ty-
pical physical distributions of both organic and inorganic
materials for an efficient (i.e., 90% BOD reduction) munici-
pal activated sludge treatment plant are shown in Table I.
The size classifications are as follows:
Class Size Range
Settleable >100 p
Supracolloidal 1-100 p
Colloidal lmn-1 p
Soluble
-------
The data in Table I, of course, represent average values, and
variations with time are typical. Table II demonstrated this
variability of the physical distribution of effluent parti-
culates (suspended solids may be approximated by the sum of
the settleable and supracolloidal groups noted above) as a
function of time.
Organic Composition
It has been estimated that secondary plants treating
municipal wastewaters produce effluents that contain approxi-
mately 55 mg/1 organic matter (3). Of this, approximately 52
mg/1 was added during use. The BOD associated with this con-
centration of organics should be about 25 mg/1. As can be
observed from Table I, about three-quarters of the organics
found in the effluent are either colloidal or soluble.
166
-------
Table I
Total Solids Distributions for an Activated Sludge Effluent.
(all results in mg/1)
(a)
Effluent
Fraction
Soluble
Colloidal
Supracolloidal
Settleable
Total
Winter, 1965-66
Organic inorganic
Spring, 1967 (b)
Organic Inorganic
71
2
16
1
90
223
1
3
0
227
62
6
24
0
92
250
2
4
0
256
(a) from reference (1)
(b) from reference (2)
167
-------
Table II
Variation in
Date
5/ 5/69
5/ 6/69
5/ 7/69
5/ 8/69
5/12/69
5/13/69
5/14/69
5/15/69
5/19/69
5/20/69
5/21/69
5/22/69
Effluent Quality of an Activated Sludge Plant ^a
(all
BOD
AM
12
9
8
8
13
14
9
10
12
17
10
19
results in mg/1)
PM
4
6
10
16
13
15
6
10
16
25
11
27
Suspended
AM
17
19
21
30
38
43
21
21
36
41
26
41
Solids
PM
8
19
27
39
33
43
11
21
43
54
16
59
(a) Courtesy of the Johns-Manville Co., Manville, N. J.
168
-------
This is also true of the distribution of other general organ-
ic parameters such as TOC and COD, as is shown in Table III.
Due to the soluble nature of most of the effluent or-
ganics, research into the chemical nature of these materials
has mainly involved the colloidal-soluble materials, or such
approximations of these catagories as filtrates or centrifu-
gates. Initial investigations into the nature of these or-
ganics did not reveal too much information. Analysis of
American effluents indicated that about 10% of the average
effluent COD was ether extractable organics, about 10% was
proteins, about 10% was anionic surfactants, about 5% carbo-
hydrates and about 5% tannins and lignins (4). Thus, about
65% of the effluent organics were unaccounted for in the
survey. In a subsequent study of a British trickling filter
effluent (Table IV), only 26% of the effluent soluble-colloid-
al organics were detected (5). A subsequent investigation of
an Israeli trickling filter effluent (Table IV) indicated
that a significant part of the previously undetected soluble
organics were humic acid like materials (6).
169
-------
Table III
Organic Parameter Distributions for an Actual Sludge Effluent (a)
(Spring, 1967)
Effluent
Fraction
Soluble
Colloidal
Supracolloidal
Settleable
Volatile Solids
mg/1
62
6
24
0
COD
mg/1
46
3
13
0
TOC
mg/1
16.5
1.5
6
0
Total
92
62
24
(a) from reference (2)
170
-------
Table IV
Chemical Composition of Soluble-Colloidal Organic Matter in a
Trickling Filter Effluent
Constituent or
Group British (a) Israeli (b)
mg/1 TOC mg/1 COD
Ether Extractables 1.7 19.6
Carbohydrates 0.2 20.2
Amino Acids - Proteins 0.3 38.9
Anionic Detergents 1.4 23.7
Tannins - 2.8
Fulvic Acid - 41.6
Humic Acid - 19.2
HymathomeIonic - 13.7
Recovery, % 26 97
(a) from reference (5)
(b) from reference (6)
171
-------
In addition to these comprehensive surveys, certain
specific organic materials have also been detected by inter-
ested investigators at various times. Thus the lower ali-
phatic (i.e., fatty) acids have been detected in the 10-100
jjg/1 range (7) , Pyrene in the <1 ^ug/1 range (8) , cholesterol
and coprostan 1 in the 10 - 100 pg/1 range (9), uric acid in
the 5 - 10 jug/1 range (10), and various non-ionic surfactants
in the •< 1 mg/1 range (11) .
There has been relatively little work done on the compo-
sition of effluent particulate organics. The one comprehen-
sive study noted in Table V detected only 39% of the particu-
late organics present in the trickling filter effluent (5).
Saturated fatty acids such as lauric,myristic palmitic and
stearic have been found in effluent particulates in concen-
trations from 0.1/ig/l, and unsaturated fatty acids such as
oleic, linoleic and linolenic /i 0.1-2 pg/l (12). The amino
acids cystine, lysine, histidine, arginine, serine, glycine,
aspartic acid, threonine, gluconic acid, alanine, proline
tyrosine, methionine, valine, phenyl alanine, leucine and
isoleucine have been detected in dried activated sludge in
concentrations of 10-40 mg/g (13), and the vitamins thiamine,
riboflavin, pyridoxine, nicotinic acid, panthothenic acid,
biotin, folic acid and Bi2 have been detected in concentrations
172
-------
of 0.1-10 ^ig/100g (14). Finally, such sugars as glucose,
lactose and arabinose are present in the particulate carbo-
hydrates (15) .
Table V
Composition of Trickling Filter Effluent Particulates(a)
(for a British Sewage)
Constituent
Fatty Acids
Fatty Esters
Soluble Acids
Carbohydrates
Concentration
mg/1 TOC
0.12
0.12
0.13
1.39
Constituent
Muramic Acid
Concentrations
mg/l TOC
0.05
Amino Sugars 0.38
Anionic Detergents 0.05
Proteins 2.74
(a) from reference (5)
173
-------
Inorganic Constituents
Unlike the organic materials found in effluents which
represent the organics added to the water during use and
modified by secondary treatment, effluent inorganics re-
flect largely the quality of the original water supply. Thus,
there is little general applicability of one set of inorganic
analyses to other circumstances, except for those materials
largely added during use such as ammonia and phosphate.
Actually, it is of more general interest to note the approxi-
mate increases in the inorganic constitutent that occurs after
each use by man, and these and general effluent inorganic
characteristics are presented in Table VI. As is implicit
in both Tables I and VI, effluent inorganics are almost all
soluble. The difference between such nationwide averages
and local effluents may be considerable, as can be observed
from examination of Table VII.
174
-------
Table VI
Average Inorganic Composition of Municipal Secondary Effluents
Constituent Concentrations Increment Addition
mg/1 mg/1
Sodium
Potassium
Calcium
Magnesium
Ammoniums
Chloride
Nitrate
Nitrite
Bicarbonate
Sulfate
Silica
Phosphate
135
15
60
25
20
130
15
1
300
100
50
25
70
10
15
7
20
75
10
1
100
30
15
25
(a) from reference (3)
175
-------
Summary
Although there have been extensive investigations into
the nature of the organic constituents of effluents, most of
the particulate organics are still unknown and even the solu-
ble organics have only been classified by solubility and
extractive procedures rather by the molecular species pre-
sent. As it represents a simpler analytic area, more is
known as to the nature of effluent inorganic constituents,
but as this reflects the original water quality as well as
its use such information is not generally applicable. Per-
haps one of the best ways of summarizing the generalities of
effluent composition would be to examine Tables VIII and IX.
which give the various constituents of a large number of
secondary treatment plants in the New York metropolitan area
(6). These data, which reflect much of the previously de-
scribed analyses, give a picture of not only the median ef-
fluent characteristics, but also the range over which these
characteristics may vary. It is interesting to note from this
data the presence of significant amounts of copper and zinc
in the effluents, and the detection at times of many of the
other heavy metals as well. These are constituents more
usually associated with treatment plant sludges, and their
presence in effluents adds another facet to their possible
environmental impacts.
176
-------
Table VI?
Average Inorganic Composition of Bernardsville, N.J. Secondary
/
Effluent.
Constituent Concentration
mg/1
Sodium
Potassium
Calcium
Magnesium
Silica
55
4
15
4
12
Constituent Concentration
mg/1
Chloride
Carbonates
Nitrate
Sulfate
Phosphate
41
23
1
1
33
177
-------
Table VIII
General Composition of Secondary Treatment Plant Effluents (a)
(New York Metropolitan Area)
Constituent
PH (2)
Biochemical Oxygen Demand
Total Carbon
Organic Carbon
Suspended Solids
Settleable Solids
Turbidity (3)
Ortho Phosphate - P
Ammonia - N
Nitrite - N
Nitrate - N
Value Distribution
Minimum
0
0
0
0
mg/1
3.9
2
17
8
1
0
3
.3
.5
.01
.2
Median
mg/1
6.9
29
60
31
25
9
16
4
15
0.1
0.9
Maximum
mg/1
7.7
149
204
174
155
109
99
19
105
3
22
(a) from reference (16)
178
-------
Table IX
Heavy Metal Constituents of Secondary Treatment Plant Effluents (a)
(New York Metropolitan Area)
Constituent Value Distribution
Copper
Zinc
Chromium
Lead
Iron
Nickel
Cadmium
Manganese
Mercury
Silver
Cobalt
Minimum
mg/1
Median
mg/1
^0.02 (b) 0.05
^0.02 (b) 0.08
Maximum
mg/1
1.50
0.92
<0.05 (b) <0.05 (b) 6.80
<0.20 (b) <0.20 (b) 0.20
<0.10 (b) <0.40 3.50
<0.10 (b) <0.10 (b) 0.80
<0.12 (b) <0.02 (b) 6.40
<0.02 (b) 0.10 0.50
<0.0001 (b) 0.0009 0.1250
<0.05 (b) <0.05 (b) <0.05 (b)
<0.05 (b) <0.05 (b) <0.05 (b)
(a) from reference (16)
(b) below detection limit
179
-------
1. Rickert, D. and Hunter, J.V., J. Water Pollut.Cont. Fed,
39, 1475 (1967) .
2. Rickert, D., and Hunter, J.V., Water Research,5, 421
(1971).
3. "Cleaning Our Environment, the Chemical Basis for
Action", Report of the Committee on Chemistry and
Public Affairs, American Chemical Society, Washington,
B.C., 1969.
4. Bunche, R., Earth, E. and Ettinger, M., J. Water Pollut.
Contr. Fed., JT3, 122 (1961).
5. Painter, H., Viney, M. and Sywaters, A., J. Inst. Sew.
Purif. , 302 (1961) .
6. Rebhan, M. and Manka, J., Environ. Sci. Technol. , _5_,
606 (1971) .
7. Murtaugh, J. and Bunch, R., J. Water Pollut. Contr.
Fed., 37, 410 (1965).
8. Wedgewood, P., J. Inst. Sew. Purif., 20, (1952).
9. Murtaugh, J. and Bunch, R., J. Water Pollut. Cont. Fed.,
19, 404 (1967) .
10. O'Shea, J. and Bunch, R., J. Water Pollut. Cont. Fed.,
37, 1444 (1965) .
11. Ministry of Technology (Brit.), Notes on Water Pollution,
No. 34, 1966.
12. Viswanathan, C., Bai, B. and Pillai, S., J. Water Pollut.
Contr. Fed., 34, 189 (1962).
13. Subrahanyan, P., Sastry, C., Rao, A. and Pillai, S.,
J. Water Pollut. Contr. Fed., 32, 344 (1960).
14. Kocher, V. and Corti, v., Schweiz. Z. Hydrol., 14,
333 (1952).
15. Brown, T., J. Protozool., 14, 340 (1967).
16. Annual Report, Interstate Sanitation Commission, New
York, New York, 1972.
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FATE OF MATERIALS APPLIED
by
Richard E. Thomas
Research Soil Scientist
National Water Quality Control Research Program
Robert S. Kerr Environmental Research Laboratory
ENVIRONMENTAL PROTECTION AGENCY
Ada, Oklahoma 74820
Prepared for Presentation at the
Conference on Land Disposal of Wastewaters
Michigan State University
Kellog Center
East Lansing, Michigan
December 6-7, 1972
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FATE OF MATERIALS APPLIED
When wastewaLers are applied to the land, a substantial quantity
of suspended and dissolved solids is deposited on the land. The fate
of these materials is an important factor to consider in the selection
of a land-based alternative for management of wastewaters. There are
four repositories which nay receive and store appreciable fractions
of the materials applied to the land at a wastewater management site:
(1) Some of the material may be volatilized and released to the
atmosphere; (2) another fraction of the material may be released
directly to surface waters with runoff; (3) particulates and some
dissolved material will be temporarily or permanently retained in
the soil; and (4) the remainder of the material will be leached
down through the soil to be stored in the groundwater. The distri-
s
bution of materials among these four repositories is dependent on
physical, chemical and biochemical interactions which take place
in the soil. These interactions in the soil are influenced by
many factors related to the characteristics of the wastewater and
to characteristics of specific land treatment sites. Some of these
factors are beyond the control of man while others can be managed
to control the fate of applied materials.
The purpose of this presentation is to describe several
management approaches which can be used to influence the fate
of materials applied to land treatment sites. The materials
to be included will be grouped into three units for convenience.
The units will be designated as suspended materials, major plant
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nutrients, and other constituents. Within each unit, the fate of
materials will be discussed in relation to three approaches to land
treatment of wastewaters. These approaches to land treatment are
based on hydrological behavior and can be described briefly as
follows: (1) Infiltration systems which are operated at relatively
high hydraulic rates and emphasize groundwater recharge as the fate
of the applied wastewater; (2) irrigation systems which are operated
at relatively low hydraulic rates and emphasize both groundwater
recharge and evaporative losses as the fate of the applied waste-
water; and (3) spray-runoff systems which are operated at inter-
mediate hydraulic rates and emphasize runoff to surface waters as
the fate of the applied wastewater.
SUSPENDED MATERIALS
Suspended materials in a wastewater settle out quickly or are
filtered out as the applied wastewater percolates through the soil.
The results of numerous studies can be cited to show essentially
complete retention of suspended materials in the soil after rela-
tively short travel distances of a few inches to a few feet depending
on the texture of the soil. Obviously continued retention and
storage of suspended solids in the soil pores would lead to clogging
of the soil pores and a sharp reduction in the permeability of the
soil. This phenonmenon has been studied extensively and researchers
have identified many factors influencing the clogging of soil pores.
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Articles by McGauhey and Krone (1), Thomas, Schwartz, and Bendixen (2),
or Thomas and Law (3) are good reference sources to obtain a more
complete understanding of the clogging process. Fortunately, a major
fraction of the suspended solids are volatile and are biochemically
oxidized to products which prevent clogging of the soil pores. In
fact, the biochemical oxygen demand exerted by this biodegradable
fraction of the suspended material is a key factor in determining the
successful operation of many land treatment systems and hence the fate
of all materials applied to the system.
Information from practical experiences with land disposal of
wastewaters shows a wide divergence in the amount of biodegradable
solids which can be applied to the soil without inducing conditions
that cause soil clogging and the undesirable effects which accompany
soil clogging. Blosser and Caron (4) recommend biochemical oxygen
demand (BOD) loadings of up to 200 Ibs./acre/day for disposal of
pulp and paper mill effluents. Thomas and Bendixen (5) report that
sewage sludge loadings equivalent to 170 Ibs./acre/day of organic
carbon can be applied to sandy soils for extended periods of
operation. Bouwer (6) reports a BOD loading of 45 Ibs./acre/day
for secondary sewage effluent. Parizek et al. (7) report BOD
loadings of less than 2 Ibs./acre/day for irrigation with secondary
effluent. An important point to consider is covered by Thomas and
Bendixen (5) in their discussion of the degradation of sewage organics
in soil. They cite several references which indicate that organic
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carbon additions of as much as 25 Ibs./acre/day are needed to
maintain a static organic matter content in the soil. Such
additions help to maintain the tilth of a soil and would not be
expected to pose problems of soil clogging. With this concept
in mind, one can make useful projections about the fate of
suspended materials applied to the soil through the three
approaches to land treatment.
Typical suspended solids concentrations found in secondary
effluents should have little effect on the operation of well
designed and well managed wastewater-irrigation systems. We can
illustrate this by assuming an effluent with 50 mg/1 of suspended
solids (of which 70 percent are biodegradable) and an irrigation
rate of 2 inches per week. Such a system would result in a total
suspended solids loading of 3 Ibs./acre/day and biodegradable
suspended solids loading of 2 Ibs./acre/day. The BOD exerted
by the biodegradable fraction of these solids is substantially
less than the 25 Ibs./acre/day of organic additions required to
maintain a static organic matter content in soils. The residual
of the nonbiodegradable fraction of the suspended materials also
represents a small contribution to the total volume of affected
soil. An acre-inch of a mineral soil weighs about 300,000 Ibs.
while the 1 Ib./acre/day of nonbiodegradable suspended solids
amounts to an addition of only 365 Ibs./acre/year. It would
be more than a decade before the added residue amounted to one
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percent of the weight of the surface inch of soil and many decades
before the residue amounted to one percent of the soil normally
mixed by plowing. From this illustration, it is clear that the
suspended solids added to the soil through wastewater irrigation
at irrigation rates of less than eight feet per year do not pose
a problem of soil clogging. The fate of much of the suspended solids
is biooxidation to gases, water, and minerals. The fate of the
nonbiodegradable fraction is accumulation in the soil, but the
quantity which may accumulate represents a very minor addition
to the total soil volume. Qualitative information from numerous
wastewater irrigation operations bears out the fact tti£.t suspended
solids do not pose specific operational problems, and the results
of research investigations such as the 14-year study by Day, Stroehlein,
and Tucker (8) show that irrigation with activated sludge effluent did
not alter soil organic matter content relative to irrigation with well
water.
Suspended solids added to the soil by the infiltration approach
have a major influence on system operation and performance because
hydraulic loading rates can range up to 300 feet per year. The
high loading rates characteristically used for infiltration systems
greatly increase the potential for soil clogging to interfere with
the successful operation of a system. The same theoretical
composition of effluent we used to illustrate the irrigation approach
will clearly demonstrate this increased potential for soil clogging.
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With our suspended solids content of 50 mg/1 (70 percent biodegradable)
and a hydraulic loading of 120 feet per year (an intermediate value),
the total suspended solids load is 45 Ibs./acre/day. This load
exceeds the organic addition needed to maintain a static organic
matter content in many soils. The BOD exerted by this amount of
biodegradable material can exceed that available in the soil
environment and lead to severe clogging of soil pores. This
phenonmenon of soil clogging is well documented, and many research
studies on this subject were reviewed by McGauhoy and Krone (1).
The importance of available oxygen for prevention of clogging is
discussed by Thomas, Schwartz, and Bendixen (2). Intermittent
dosing and drying periods are effective for avoiding the problem
of soil clogging and assuring that the fate of suspended materials
is biooxidation to gases, water and minerals. Successful operation
of infiltration systems for decades at many locations throughout
the United States provides qualitative support on the fate of
suspended solids, but quantitative data are unavailable or meager
for most of these installations. Quantitative information available
from the results of research studies does verify that the fate of
suspended solids is biooxidation with accumulation of some residue
in the surface soil. Research conducted by Bouwer at Phoenix,
Arizona, resulted in excellent suspended solids removals with a
BOD loading of 45 Ibs./acre/day at a hydraulic loading of 300
feet per year with an activated sludge effluent. Studies by
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Larson at Detroit Lakes, Minnesota (10), indicated successful
operation with a BOD loading of 23 Ibs./acre/day at a hydraulic
loading of 95 feet per year with secondary effluent.
Suspended solids added to the soil through the spray-runoff
approach pose a different situation for removal. The liquid does
not percolate downward through the soil, and the filtering capability
of the soil is not involved in the removal of the suspended materials.
The principal mechanism of removal is still biooxidation, but the
biooxidation must be accomplished as the liquid moves slowly across
the surface of the soil. There is no problem of potential soil
clogging, but the suspended solids still have a major influence on
system operation through the BOD which they exert. The successful
operation of spray-runoff systems is dependent on maintaining an
oxygen Jevel in the soil which sustains biooxidation of organic
materials applied to the soil. Since maintenance of biooxidative
conditions is a prerequisite for successful operation of a system,
the fate of biodegradable suspended solids is oxidation to gases,
water, and minerals. The use of the spray-runoff approach for
land treatment of wastewaters has been limited, and there are only
a few examples to substantiate the fate of suspended solids added
to the soil by the spray-runoff approach. Law, Thomas, and Myers (11)
reported 94 percent reduction in suspended solids concentrations at
a loading of 20 Ibs./acre/day of suspended solids (48 Ibs./acre/day
of BOD) for a spray-runoff system treating cannery wastewater applied
188
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at the rate of 0.36 inches per day. Kirby (12) reports that the
grass filtration system at Melbourne, Australia, achieves 95 percent
removal of suspended solids at a loading of 34 Ibs./acre/day of
suspended solids (68 Ibs./acre/day of BOD) with raw domestic sewage
applied at the rate of 0.75 inches per day. The spray-runoff
approach to land treatment does not achieve the virtually complete
removal of suspended materials achieved by the irrigation approach
and the infiltration approach because some material usually remains
in suspension and is carried in the runoff from the treatment plots.
MAJOR PLANT NUTRIENTS
The major plant nutrients which are of particular concern at
this time are nitrogen and phosphorus. Each of these nutrients enter
into many interactions within the plant-soil complex. Dr. Erickson
has covered the mechanisms of these interactions in a companion paper,
and I shall limit my discussion to the fate of these nutrients for
practical utilization of the three approaches to land treatment of
wastewaters.
Typical nitrogen and phosphorus concentrations in secondary
effluents are such that crop uptake plays an important role in the
fate of these nutrients for the wastewater irrigation approach. Turning
once again to our theoretical effluent, we can add characteristic concen-
trations of 20 mg/1 for nitrogen and 10 mg/1 phosphorus to illustrate
the fate of these nutrients. With our irrigation rate of 2 inches per
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week and applications during a projected growing period of 30 weeks,
the nitrogen loading would be 270 Ibs./acre and the phosphorus loading
would be 135 Ibs./acre. A 25 ton/acre yield of ensilage corn is one
example of many crops which could utilize essentially all of the 270
Ibs./acre of nitrogen applied to the soil. This removal of nitrogen
by crop uptake is essential to the irrigation approach because excess
nitrogen is converted to the mobile nitrate ion which is carried into
the groundwater by soil percolate. Our 25 ton/acre yield of ensilage
corn would remove approximately 30 Ibs. of the 135 Ibs./acre of
phosphorus added to the soil in the applied wastewater. As discussed
by Dr. Erickson, the phosphorus in excess of that removed by the crop
is not readily leached from the soil. In fact, many soils have the
capacity to retain thousands of pounds of phosphorus within the
soil profile while the leachate from the soil contains only a trace
of phosphorus. This capability of the soil to retain and fix
phosphorus is as important to the removal of phosphorus as crop
uptake is to the removal of nitrogen since phosphorus applications
exceed potential crop uptake by a substantial margin. The experi-
mental study at Pennsylvania State University (7) is a good example
of nitrogen removal by crop uptake and phosphorus removal by reten-
tion in the soil. Of particular local interest is the work of Ellis
and Erickson (13) on the phosphorus retention of many Michigan soils.
The high application rates used for the infiltration approach
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negate the influence of crops as a factor in the fate of major
nutrients. Applying the 20 mg/1 of nitrogen and 10 mg/1 of
phosphorus of our theoretical effluent to the 120 feet per year
hydraulic loading for the infiltration approach produces a nitrogen
loading of about 6,500 Ibs./acre/year and a phosphorus loading of
about 3,300 Ibs./acre/year. Crop uptake can account for little of
these totals, and crop removal is not a significant factor in the fate
of major plant nutrients for the infiltration approach to land treat-
Bent. The fate of nitrogen applied by the infiltration approach is
largely dependent on nitrogen removal by microbial denitrification
of the nitrogen to gaseous nitrogen with release to the atmosphere.
Management techniques to promote this process are in the early stages
of development, and much of the applied nitrogen can be expected to
appear in the underdrainage or groundwater in the nitrate form.
Management techniques to promote denitrification were studied by
Bouwer (6), and he achieved up to 80 percent removal of the 21,000
Ibs./acre/year of nitrogen applied to the soil. The operational
procedure* followed by Larson (10) promoted microbial nitrification
rather than denitrification, and nitrate nitrogen concentration in
the groundwater rose to 31 mg/1. Phosphorus removal for the infil-
tration approach is achieved by retention in the soil through the
mechanisms described by Dr. Erickson in his companion paper. Finer
textured soils have the best capability to retain phosphorus, but
coarse textured soils suitable for the infiltration approach can
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also achieve excellent phosphorus removal. The process of phosphorus
removal is also less dependent on specific management techniques.
Continuing with the same research studies, we find that Bouwer (6)
reported about 95 percent removal of the 21,000 Ibs./acre/year of
phosphorus applied with his management techniques after about 200
feet of lateral movement through the soil while Larson (10) reported
75 percent removal of the 2,400 Ibs./acre/year applied with his
management techniques after about 10 feet of vertical movement through
the soil. These examples serve to indicate that infiltration systems
can be managed so that retention in the soil is the fate of the applied
phosphorus.
The application rates used for the spray-runoff approach also
reduce the importance of crop uptake as a factor in determining the
fate of nitrogen and phosphorus. With the projected concentrations
of 20 mg/1 for nitrogen and 10 mg/1 for phosphorus in our theoretical
effluent and a hydraulic load of 0.4 inches per day [comparable to
rates reported by Kirby (12) and Law, Thomas, and Myers (11)], the
nitrogen loading would be 650 Ibs./acre/year and the phosphorus
loading would be 325 Ibs./acre/year. Crop uptake of 250 Ibs. per
acre of nitrogen and 30 Ibs. per acre of phosphorus are appreciable,
but they leave the major fraction of the nutrients for a fate other
than crop removal. The major mechanism for nitrogen removal in the
spray-runoff mode of operation is by denitrification. An environment
which promotes denitrification must be achieved by adjusting the
hydraulic load and hence the BOD load to maintain a low dissolved
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oxygen level which is favorable for denitrification. Kirby (12)
reports 60 percent removal of total nitrogen from raw sewage applied
at a rate of 0.8 inches per day but does not indicate the nitrogen
balance. Law, Thomas, and Myers (11). reported 90 percent mass
removal of nitrogen from cannery wastewater with a nitrogen loading
of 515 Ibs./acre/year. Phosphorus removal by the spray-runoff
mode of operation is relatively inefficient with present operating
procedures. The processes which retain phosphorus in the soil
cannot be brought into play as the liquid moves over the surface
of the soil. A substantial fraction of the phosphorus applied in
the spray-runoff mode of operation will be carried in the runoff
unless special steps are taken to improve the removal of phosphorus.
Kirby (12) reports 35 percent removal of phosphorus for spray-runoff
treatment of raw sewage applied at 0.8 inches per day. Law, Thomas,
and Myers report two levels of phosphorus removal for cannery waste-
water with a phosphorus loading of 224 Ibs./acre/year. Daily appli-
cations of wastewater applied over a 6 to 8-hour period of spraying
resulted in phosphorus removals of about 55 percent or 120 Ibs./acre/
year, while the same amount of total application put on with 12-hour
spray periods three times per week resulted in phosphorus removals of
88 percent which would amount to 180 Ibs./acre/year of the 224 Ibs./acre/
year applied to the soil.
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OTHER CONSTITUENTS
Treated wastewaters contain a host of other constituents in widely
varying amounts including substantial quantities of soluble salts such
as sodium chloride and minor amounts of trace constituents such as
heavy metals and pesticides. This grouping of other constituents is
a highly variable component depending on the source of the original
water supply and the sources contributing to the final composition of
the wastewater during collection. in addition to the variability due
to source, individual constituents may undergo many different inter-
actions in the plant-soil environment. Fragmentary information is
available about the fate of many specific constituents of interest,
but much remains to be learned about the behavior and hence the fate
of trace constituents added to the soil through the various approaches
of land treatment for wastewater management. Although it is imprac-
tical to make many generalizations based on the fragmentary informa-
tion currently available, there are some readily predictable results
associated with the three approaches to land treatment for management
of wastewaters.
The fate of soluble salts or total dissolved solids applied to
the land is usually surface waters through runoff or groundwater
through percolating soil water. The soil has little capacity to
retain most soluble salts commonly found in treated wastewaters,
and the only mechanism for appreciable accumulation of total dissolved
salts in the soil is a lack of sufficient percolating water to leach
the salts from the soil. Since the primary fate of total dissolved
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solids is the effluent from the land treatment system or the
"renovated wastewater," it is important to remember the fate of
the water applied to the land through the irrigation, infiltration,
and spray-runoff approaches to land treatment. The loadings of 2-
to 8-feet per year for the crop irrigation approach are such that
the balance between evapotranspiration and rainfall can substantially
influence the fate of the applied water and the concentration of
total dissolved salts in the water percolating downward through the
soil. An excess of evapotranspiration over rainfall reduces the
amount of water percolating downward but increases the concentration
of dissolved solids in the percolate. If the excess of evapotrans-
piration over rainfall is great enough, the fate of some of the
dissolved solids will be an accumulation in the soil. An excess
of rainfall over evapotranspiration increases the amount of water
percolating downward through the soil and decreases the concentration
of dissolved solids in the percolate. The high loadings employed
for the infiltration approach nullify the effects of evapotrans-
piration or rainfall on the concentration of dissolved solids in
the underdrainage. For example, the projected loading of 120 feet
per year which has been used to illustrate the fate of suspended
solids and major plant nutrients would not be appreciably affected
by net differences between evapotranspiration and rainfall found
anywhere in the United States. The spray-runoff approach is intended
to minimize the amount of water percolating through the soil to the
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groundwater and return a substantial fraction of the applied waste-
water to surface waters after treatment. The primary fate of the
dissolved solids becomes surface waters in much the same manner as
the fate of dissolved solids is surface waters for conventional
treatment approaches. The concentration of dissolved solids in
the water discharged to the surface waters is influenced by the
day-to-day balance between evapotranspiration and rainfall, and
a minor fraction of the dissolved solids are carried downward
with the soil percolate. To summarize the fate of dissolved solids
briefly one can say that dissolved solids applied by the irrigation
and infiltration approaches end up in groundwater unless the under-
drainage is intercepted and diverted to another sink such as a
surface stream while the dissolved solids applied by the spray-
runoff approach are released directly to surface waters.
Heavy metals and pesticides are two groups of other constituents
which are in the limelight at the present time. The presence of both
of these groups of other constituents in wastewaters is highly
dependent on the industrial contribution to the wastewater, and
most of the members of these two groups undergo physical, chemical,
or biochemical interactions in the soil. Fragmentary information
about the fate of many specific constituents of interest is available,
but much remains to be learned about the behavior and hence the fate
of trace constituents such as heavy metals and pesticides. Many of
the heavy metals are strongly held in the soil by the mechanisms
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Dr. Erickson has described in the paper he prepared for this Conference.
Retention of heavy metals in the soil may be a desirable fate or it
may be an undesirable fate. Allaway (14) presents an interesting
review on the cycling of trace elements in relation to crop production
and human health. He suggests that future agricultural management
practices may include control of trace element concantrations in
plants through the control of trace element concentrations in soils.
The report of the National Technical Advisory Committee on Water
Quality Criteria (15) includes a discussion of both heavy metals and
pesticides in waters to be used for crop irrigation. This discussion
includes a tabular presentation of concentration limits as they
pertain to irrigation on various types of soils and for short-term
use (up to two decades) versus continuous long-term use. An
important factor to remember when dealing with trace constituents
such as heavy metals and pesticides is that the total mass of
material involved is small, and what would appear to be rather
insignificant factors can account for appreciable fractions of
the total applied mass.
SUMMARY
The foregoing is a brief summary of the fate of suspended
solids, major plant nutrients of environmental concern, and other
selected constituents of wastewaters when these wastewaters are
applied to the soil by the crop irrigation, infiltration, or
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spray-runoff approaches to wastewater management. The content of
this presentation is intended to give one an insight into the
mechanisms involved and the practical aspects involved in the
treatment or renovation of wastewater by applying the wastewater
to the land. The coverage of the many topics involved is of
necessity brief, and one wishing to have a deeper understanding
of the subject matter should refer directly to the cited literature
and other pertinent reference documents on interactions in the plant-
soil environment.
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REFERENCES
1. McGauhey, P. H., and R. B. Krone, "Soil Mantle as a Wastewater
Treatment System - Final Report," School of ?ublic Health,
University of California, Berkeley, SERL Rept. No. 67-11, 1967.
2. Thomas, R. E., W. A. Schwartz, and T. W. Bendixen, "Soil Chemical
Changes and Infiltration Rate Reduction Under Sewage Spreading,"
Soil Sci. Soc. of America Proc., Vol. 30, No. 5, pp. 641-646,
September-October 1966.
3. Thomas, R. E., and James P. Law Jr., "Soil Response to Sewage
Effluent Irrigation," Municipal Sewage Effluent for Irrigation,
The Louisiana Tech Dept. of Agricultural Engineering, Box 4337,
Ruston, LA., pp. 5-19, 1968.
4. Blosser, Russell 0., and Andre L. Caron, "Recent Progress in Land
Disposal of Mill Effluents," Tappi, Vol. 48, No. 5, pp. 43A-46A,
May 1965.
5. Thomas, R. E., and T. W. Bendixen, "Degradation of Wastewater
Organics in Soil," Jour. Water Pollution Control Fed. 41,
pp. 808-813, 1969.
6. Bouwer H., "Water Quality Aspects of Intermittent Systems
Using Secondary Sewage Effluent," Artificial Groundwater
Recharge Conference, University of Reading, England, Paper 8,
September 1970.
7. Parizek, R. R., et al., "Waste Water Renovation and Conservation,"
The Pennsylvania State University Studies No. 23, University Park, PA,
71p., 1967
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8. Day, A. D., J. L. Stroehlein, and T. C. Tucker, "Effects of
Treatment Plant Effluent on Soil Properties," Journal Water
Pollution Control Federation, Vol. 44, No. 3, pp. 372-375,
March 1972.
9. Thomas, R. E., and T. W. Bendixen, "Pore Gas Composition Under
Sewage Spreading," Soil Sci. Soc. of America Proc. 32,
pp. 419-423, 1968.
10. Larson, Winston C., "Spray Irrigation for the Removal of Nutrients
in Sewage Treatment Plant Effluent as Practiced at Detroit Lakes,
Minnesota," Algae and Metropolitan Wastes, Transactions of the
1960 Seminar, United States Department of Health, Education, and
Welfare, pp. 125-129.
11. Law, James P., Jr., R. E. Thomas, and Leon H. Myers., "Cannery
Wastewater Treatment by High-Rate Spray on Grassland," WPCF Jour.,
Vol. 42, No. 9, pp. 1621-1631, September 1970.
12. Kirby, C. F., "Sewage Treatment Farms, Post Graduate Course in
Public Health Engineering, Session No. 12," Dept. of Civil Eng.,
University of Melbourne, Mimeograph 14p., 1971.
13. Ellis, B. G., and A. E. Erickson, "Movement and Transformation of
Various Phosphorus Compounds in Soil," Michigan State University,
Mimeograph 35p ., 1969.
14. Allaway, W. H., "Agronomic Controls Over the Environmental Cycling
Of Trace Elements," Advances in Agronomy 20, pp. 235-274, 1968.
15. National Technical Advisory Committee on "Water Quality Criteria,"
FWPCA, Government Printing Office, Washington, D.C., 234p., April 1968.
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PROTECTION OF THE PUBLIC HEALTH
by
Charles A. Sorber, Ph.D., P.E.
Major, MSC
Presented at
Symposium - Land Disposal of Municipal Effluents and Sludges
Rutgers University - The State University, New Brunswick, NJ
12-13 March 1973
US Army Medical Environmental Engineering Research Unit
Aberdeen Proving Ground, MD 21010
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The public health aspects of wastewater treatment or wastewater
reclamation by land disposal are dependent upon a number of variables,
the most important of which is the ultimate use of the wastewater.
Possible uses include: (a) discharge to a surface body following
percolation through the soil; (b) groundwater recharge; (c) crop
irrigation; and, obviously, any combination of the first three. The
ultimate use of the wastewater along with the method of application of
the wastewater are intimately interrelated with soil character and
application rates.
Another area of importance is the degree of pre-treatment for the
wastewater prior to land disposal. Common sewage treatment practices
remove significant amounts of many of the important sewage constituents.
However, none of the common treatment practices can reduce the level of
all pollutants to the extent which would permit the effluent to be
employed for direct reuse as a municipal potable water supply. The
effects of these prime variables are grouped into three areas of
consideration: physical; biological; and chemical.
PHYSICAL CONSIDERATIONS
Physical considerations are somewhat secondary in that they relate,
to a large degree, to both the biological and chemical considerations.
Particular attention must be paid to the removal of suspended material,
which will insure that both the distribution system and the soil treatment
system do not become clogged. The physical characteristics of the soil
treatment system are infinitely important. Okun1, in 1971, pointed out
that wide variations in soil characteristics make it mandatory that each
potential land disposal site be intensely studied before land disposal
practices are instituted. Many investigators have indicated that clays
are chemically the most important size faction of soil. Ion exchange
capacity is a major factor and must be considered in land wastewater
disposal plans. As you will see shortly, the physical characteristics
of the soil are very closely interrelated with both the biological and
chemical considerations of land disposal.
BIOLOGICAL CONSIDERATIONS
Most standards on land disposal of wastewater provide for use
restrictions depending on how crops are processed or land is used.
For example, the California standards2 require "adequately disinfected
filtered wastewater"... for irrigation of forage crops, landscape in
lOkun, D. A., "New Directions for Wastewater Collection and Disposal",
Journal Water Pollution Control Federation, 43:11:2171, (1971).
2Foster, H. B., Jopling, W. F., "Rationale of Standards for Use of Re-
claimed Water," Journal of the Sanitary Engineering Division, Pro-
ceedings of the American Society of Civil Engineers, 95:SA3:503-514
(Jun 69).
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public areas, and for filling impondments for recreation. These standards
define "adequately disinfected filtered wastewater" as water which has
been oxidized, coagulated or filtered, and chlorinated to the extent, that
the seven-day median residual coliform count does not exceed 2.2 or 23.0
organisms per 100 ml, depending on the specific application. In another
section of the California standards "disinfected wastewater" is defined
as "water in which pathogenic organisms have been destroyed". (Just as
a side thought, it appears that there is a slight conflict in these two
statements, in as much as complete destruction of pathogenic organisms
and the presence of as many as 23 coliforms/100 ml are inconsistent).
Evidence collected in the field has shown high coliform levels on the
surface of vegetables irrigated with raw sewage. Other researchers have
suggested that if sewage irrigation is stopped one month before harvest,
raw food would not likely be an effective transmission medium of bacterial
enteric disease. However, there is sufficient information to substantiate
the current requirement for disinfection of wastewater before irrigation
of vegetables or any other crop for direct human consumption. Health
problems, however, can arise from the use of either inadequately dis-
infected or undisinfected wastewater.
It has been repeatedly demonstrated that many pathogenic microorganisms
pass through activated sludge treatment even though they are greatly
reduced in number. A wide variety of microorganisms have been found in
secondary effluents, including the typhoid group, colorea, tuberculosis,
and many viruses including coxsackie, polio virus (I, II and III), echo
viruses, and others. Even after chlorination, many enteric microorganisms
can be found in secondary effluents. Kruze and co-woikers3 have demon-
strated that in the presence of ammonia, amino acids or other nitrogen
compounds, the absence of coliform organisms does not necessarily mean
virus inactivation. The effectiveness of disinfection, as measured by
the residual coliform bacteria, does not by any measure insure the
destruction of viable enteric viruses. It is clear from the literature
that, chlorination as practiced, does not provide complete disinfection
of pathogenic bacteria or viruses. As a consequence, wastewater spraying
could result in biological aerosol formation and could, and I emphasize
could, disseminate many of the pathogenic organisms found in wastewater.
3Kruze, C., Y. C. Hsu, A. Griffiths, R. Stringer, "Halogen Action on
Bacteria Viruses and Protoza," Proceedings of the National Specialty
Conference on Disinfection, University of Massachusetts, Amherst,
Massachusetts, Jul 1970, (1970).
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The application of wastewater to soil has been studied to some extent
with regard to pathogen mobility and destruction in soils. Basically,
pathogen removal in soils is a function of the characteristics of the
soil. Under certain conditions, such as limestone crevicing, pathogens
have been found to travel miles. On the other hand, it appears that
heavy textured clay soils thru adsorption and filtration, will remove
viruses, bacteria as well as the larger pathogens, on and near the soil
surface. The pathogens which are collected in the soil can be inactivated
after land application. lixposure to ultraviolet light, oxidation,
dessication and antagonistic soil organisms are the most important
destructive mechanisms. On the other hand, there is ample literature
citation to indicate that pathogens can survive these deletarious effects
in soil for relevantly long periods after sewage application.
These facts allow us to reasonably inquire about some potential
health hazards. One may ask, first, if soil runoff, either during
effluent application or following precipitation, may allow significant
numbers of pathogens to enter surface waters. Much of this problem could
be controlled or avoided by proper design of the application site. How-
ever, this may be difficult in sites spread over considerable land areas,
such as golf courses, forests, and crop lands, where runoff collection
and retention may be impractical. It is also important to consider
pathogen concentration near the soil surface. Consideration should
be given to the effects of long term application of non-degradable
organic materials that may clog the soil surface and other organics
that tie-up soil adsorption sites; the effect of cation species and
concentration with respect to soil tightness and adsorption; the effects
of high pll on soil fiIterability and reduced adsorption capability; and
lastly, the reduced treatment capabilities of soil for pathogens after
shock loading of a toxic effluent (from spills).
It has also been shown that coliform organisms do not survive in
soil and on vegetation as long as certain other bacteria such as
salmonella, kiebsiella, and some worm eggs. Virus survival on soil
is essentially unexplored. It is likely, however, that viruses will
survive longer than coliform organisms. It is important to consider
whether pathogenic organisms from sewage effluent can survive on soil
and vegetation for extended times, since they may be concentrated on
or near the soil surface. Human contact with organisms on soil surfaces
may result from dusts or other particles, winds, machinery, or other
human activity such as walking, which may reaerosolize these organisms
and make them accessible to inhalation.
Aerosols are defined as particles in the size range of .01 to 50 or
so microns (pm) which are suspended in air. Specific studies of bio-
logical aerosols emitted by spray irrigation of wastewater have not been
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found in the literature. However, some preliminary work at the University
of Utah has demonstrated that the spraying of chlorinated effluent for
landscape watering resulted in approximately 1 1/2 times the number viable
organisms that were detected from a trickling filter. Specific quantifi-
cation of this work is difficult because of the lack of experimental
control, but it does demonstrate that spray irrigation of chlorinated
effluent produces biological aerosols in the same order of magnitude as
observed from non-chlorinated wastewater applied to trickling filters.
Some investigations have been conducted on biological aerosols from
trickling filters and activated sludge systems. In general, it was found
that bacterial aerosols remain viable and travel further with increased
wind velocity, increased relative humidity, lower temperatures and
darkness.
Direct means of human infection by biological aerosols is by inhalation.
The infectivity of a biological aerosol is further dependent on the depth
of respiratory penetration. Biological aerosols in the 2-5 micron size
range are primarily captured in the upper respiratory tract. These parti-
cles are removed by the bronchial cilia and may ultimately pass into the
digestive tract. If gastro-intestinal pathogens are present in these
aerosols, a certain degree of infection may result. However, a much
higher incidence of infection will result when respiratory pathogens are
inhaled into the alveoli of the lung. The greatest alveolar deposition
occurs in the 1-2 micron range and then decreases to a minimum at
approximately 0.25 micron. Below 0.25 micron, alveolar deposition again
increases due to Brownian movement in the lungs. For comparative purposes,
it has been observed in one study that approximately 821 of the 1 micron
particles; 28% of the 0.1 - 0.3 micron particles; and 51% of 0.03 parti-
cles are deposited in the alveoli. Deposition of the smaller particles
becomes significant when consideration is given to the size of a virus
(about 0.01 - 0.1 micron).
It is reasonable to postulate that, if disinfection of sewage is not
complete and the pathogenic organisms are aerosolized, even very low
numbers of these organisms may be a potential public health hazard. On
the positive side of the ledger is the fact that dessication and oxidation
of microorganisms in aerosols is probably very important in eliminating
their overall viability. Studies of evaporation rates show that a 50
micron water droplet will evaporate in 0.31 seconds in air with a 50%
relative humidity and a temperature of 22°C. Coliforms are known to
dessicate quite rapidly whereas klebsiella and other organisms are known
to be relatively resistant to dessication. In all, it is a large area
which has not been completely explored at this point.
Another area where considerable emphasis is developing is the effect
of wastewater land disposal on the changes in both the population and
the disease incidents amongst wild animals, birds, and mosquitos.
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Some work has been directed toward these areas and more is underway. For
example, it has been demonstrated that surface ponding can develop on the
spray irrigation site, and the existence of these ponds will result in
increased mosquito breeding by several known disease vector species.
Additional areas in which information is needed include the fate, possible
spread and control of protozoan parasites; the possible passive spread of
microorganisms by flying insects; and the capacity of wildlife, including
migratory birds, to carry infection great distances from the primary
focus.
CHEMICAL CONSIDERATIONS
The public health aspects of land disposal of wastewcters must also
consider organic and inorganic chemical movement in the soil. This
evaluation could be extremely broad in scope if industrial wastewaters
are considered, either separately or combined with domestic wastewaters.
Heavy metals or toxic organic compounds are two groups of materials that
would require special consideration. Certain heavy metals including
chromium, copper, manganese, lead, and zinc, have increased in concentra-
tion in soil when digested sludge has been applied. Of these metals,
zinc and manganese have increased in concentration of the leachates, also.
It is recognized that essentially no definitive information is avail-
able as to the specific organic chemical makeup of effluents from secondary
sewage treatment processes. Because of this, it is extremely difficult
to accurately assess the long range effect of these chemicals and their
relationship to the public health aspects of land disposal. The movement
of dissolved inorganics with percolating water is primarily dependent on
the nature of the filtering soil. There have been several instances of
groundwater contamination by soluable industrial wastes. For example,
in one case in Germany, picric acid traveled several miles and caused
abandonment of a groundwater supply. Chemical elements are primarily
removed in soil media by the process of ion exchange. Therefore, the
chemical clarification ability of the soil is generally proportional to
its cation exchange capacity. Clay and organic soils have the greatest
cation exchange capacity.
Pesticides are a special case and they persist in soil and water
systems for varying periods of time. Their length of persistence depends
on such factors as the chemical nature of the pesticide itself and the
chemical, physical and biological factors which promote degradation,
translocation or metabolism.
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In 1971, Hermanson and co-workers'* established persistency indices
for various organochlorine insecticides applied to soils over a 11-year
period. They found relative persistences of pesticides in the soil:
from DI7T - .26; Dieldrin - .22; Endrin - .20; Heptochlor - .14; Chlora-
dane - .13; where unity is equal to no degradation or other disappearance
during the first year. Due to the persistence of pesticides, considera-
tion must be given to their possible build-up in the soil at wastewater
disposal sites.
Another compound of particular interest is nitrogen. Biologically
treated domestic wastewater contains between 5 and 30 milligrams/liter
of total nitrogen. The primary source of this nitrogen metabolism in
man. The dominant nitrogen form depends on the specific type of pre-
treatment process, but it is usually in the form of ammonia or nitrate.
If ammonia exists as the dominate nitrogen form, it will be adsorbed
by the soil and eventually be used in plant growth, evolve as a gas
or be biologically oxidized to nitrate. Thus, if nitrate is not
applied initially, it may be formed biologically on or near the soil
surface. Ample information is available which indicates that nitrate
ions are not adsorbed by the soil and will eventually get into the
groundwater system if not utilized immediately. As you will recall,
nitrate ion has been demonstrated as the causative agent for methemoglo-
bineraia in children. Nitrate-nitrogen levels may develop to above 10
mg/1 in areas where land wastewater disposal is used for groundwater
recharge and where the recharge water is cycled back through the water
supply system. Studies at the Penn State University have demonstrated
that selected crops can remove considerable quantities of nitrate-
nitrogen.
Another element which may be of concern is sodium. Sodium has been
shown to be a problem with cardiac patients, and, further, has been shown
to pass essentially uneffected through the soil treatment system. Again,
the only potential problem from nitrate-nitrogen and sodium would be in
areas where land disposal is the first step in a water recycle program.
In summary then let me attempt to put all this information into
perspective. There are very few, if any, public health problems that
have been demonstrated as a result of spray irrigation or land disposal
of wastewater. However, a significant number of questions have been
raised and it appears to be judicious to conduct well planned investiga-
tions which will demonstrate beyond a shadow of doubt, whether these
potential problems do or do not exist. In general, then, it can be
concluded that:
uHermanson, H. P., F. A. Gunther, L. D. Anderson, M. J. Garber, "In-
stallment Application Effects upon Insecticide Residue Content of a
California Soil," J. Agr Food chem, 19:4:722, (1971).
207
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1. Many of the potentially detrimental health and hygiene aspects
of land disposal would be significantly reduced by proper wastewater
pretreatment, including secondary treatment, filtration and complete
disinfection.
2. Site selection is extremely important.
3. By choosing a land disposal site that has from five to ten feet
of continuous fine soil, biological contamination of groundwater should
be avoided.
4. If significant numbers of organisms are present in the effluent,
the probability of inhaling pathogenic aerosols near a spray irrigation
site would be significant.
5. Chemical components of sewage may enhance the viability of
bacteria, virus and protozoans in aerosols.
6. Pathogenic microorganisms (bacteria and viruses) may survive
longer in sewage aerosols and in soil than common indicator organisms
such as colifonn organisms.
7. As a result of ponding in land disposal areas, mosquito breeding
is enhanced.
8. In areas where land disposal is the first step in a water recycle
program, total dissolved solids, sodium and nitrate ion build-up in the
groundwater supply can eventually be a problem.
Many of the unknown areas relating to the public health problems
associated with land disposal of wastewater can be more clearly identi-
fied when results of six basic study areas are available:
1. The evaluation of the survival, distribution and hazard of
aerosolized pathogenic microorganisms disbursed by spray irrigation
machinery.
2. The comparison of pathogen survival in soils and aerosols vs_
estimated indicators of bacteriological water quality.
3. The evaluation of the long range effects of land wastewater
disposal on plants, animal and disease vector ecology.
4. The evaluation of the persistence and translocation of toxic
trace organics, pesticides and heavy metals in soils at wastewater disposal
sites.
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5. An investigation into advanced treatment and disinfection methods
required to eliminate any identified problem chemicals and microorganisms
from applied wastewater.
6. The performance of a well planned epidemiological investigation
at a relatively large, operating land wastewater application site.
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EXPERIENCES WITH LAND SPREADING OF MUNICIPAL EFFLUENTS
by
Richard E. Thomas and Curtis C. Harlin, Jr.
National Water Quality Control Research Program
Robert S. Kerr Water Research Center
ENVIRONMENTAL PROTECTION AGENCY
Ada, Oklahoma 74820
Prepared for Presentation at the
First Annual IFAS Workshop on Land Renovation
of Waste Water in Florida
Tampa, Florida
May 31-June 1, 1972
Preceding page blank
211
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EXPERIENCES WITH LAND SPREADING OF MUNICIPAL EFFLUENTS*
by
Richard E. Thomas and Curtis C. Harlin, Jr.**
Introduction
The U.S. Environmental Protection Agency (EPA) is a very young
agency which was created in December 1970. Although the agency is
less than two years old, its experiences with land spreading of munici-
pal effluents extend over more than 15 years. This longer period of
experiences stems from the efforts of our predecessor agencies which
include the Federal Water Quality Administration, the Federal Water
Pollution Control Administration, and the U.S. Public Health Service.
These past efforts were conducted as a result of the Federal Water
Pollution Control Act of 1956 and subsequent amendments of this Act.
Within the current organization of EPA, the National Water
Quality Control Research Program located at the Robert S. Kerr Water
Research Center, Ada, Oklahoma, is actively participating in research
to improve our understanding of the processes which influence and
* To be presented at the First Annual Institute of Food and Agricul-
tural Sciences (IFAS) Workshop on Land Renovation of Waste Water
in Florida, May 31-June 1, 1972, Tampa, Florida.
** Research Soil Scientist and Chief, respectively, National Water
Quality Control Research Program, Robert S. Kerr Water Research
Center, EPA, Ada, Oklahoma 74820.
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limit the performance of land-based wastewater management systems.
The primary goal of this research is to advance the state of the art so
that sound technology will serve as a base for reliable design of sys-
tems to achieve desirable and specific levels of performance.
Our evaluation of the current state of the art leads us to conclude
that there are several distinctly different approaches to the spreading
of municipal effluents on the land which show promise for further
development and widespread use. It is convenient to group these
land spreading approaches into three categories which we refer to as
(1) infiltration-percolation, (2) cropland irrigation, and (3) spray-
runoff. We use this grouping because each of these approaches has
well-defined differences regarding land area requirements and the
resulting interactions with the plant, soil, and water components of
localized ecosystems.
The infiltration-percolation group includes systems frequently
referred to as recharge basins, ridge-and-furrow basins, or flooding
basins. Systems of this lype are operated on the basis that the applied
wastewater moves downward through the soil for treatment. Coarse
textured soils are preferred in order to achieve the desired areal
loadings which range up to 400 feet per year under ideal conditions.
The chief functions of plants are the relatively minor roles of
shading the surface of the soil and helping to stabilize good physical
conditions in the soil. Physical, chemical, and biochemical inter-
actions in the soil are the major processes contributing to treatment
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of the applied wastewater. Surface runoff is prohibited; evaporative
losses are relatively minor; and substantially all of the renovated
water becomes groundwater.
Crop irrigation is an immediate and direct reuse of a municipal
effluent for beneficial production of crops not for direct human con-
sumption. Common broad irrigation or spray irrigation techniques
are used to apply the effluent to crops at normal irrigation rates or
somewhat in excess of these rates. Land area requirements are large
because areal loadings are one to two inches per week with total grow-
ing season applications of less than 8 feet per year. Plants play a
prominent role in the removal of plant nutrients such as nitrogen and
phosphorus. Physical, chemical, and biochemical interactions in the
soil are less dominant in achieving desired performance because of the
relatively low rate of areal loading. Surface-runoff may or may not be
controlled; evapotranspiration losses may be equal to or greater than
the amount of water moving through the soil to become groundwater.
This large percentage of evaporative losses can result in a substantial
increase in the total salt content of the water percolating down through
the soils .
The spray-runoff is especially suited to use with impermeable
soils and falls intermediate between the infiltration-percolation
approach and the crop irrigation approach in land area requirements.
Vegetative cover is necessary to stabilize the carefully prepared
runoff slopes and terraces, but the harvesting of a crop is secondary
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to the objective of treating the applied effluent. The physical, chemi-
cal, and biochemical processes take place as the liquid moves slowly
over the surface of the soil by sheet flow. More than half of the
applied effluent is returned directly to surface waters as planned and
controlled runoff of the renovated water. The remainder of the water
is either lost through evaporative processes or percolates down
through the soil to become groundwater. A comparison of selected
characteristics of the three land-spreading systems is presented in
Table 1.
Now, let us consider some research studies which have been
conducted or financially supported by EPA or its predecessor agencies.
Discussions of the results of these studies will provide additional
detail about system designs and management techniques which can be
utilized to achieve specified treatment or reuse objectives. The three
categories of land spreading will be discussed in the same sequence
in which they have been described in preceding paragraphs.
Infiltration-Percolation Systems
Infiltration-percolation approaches such as septic tank-soil
absorption systems, ridge and furrow basins, and flooding basins
have been utilized for many decades as a convenient disposal practice.
Design and operation of these systems have emphasized the disposal
concept, and it is only within the last decade that an effort has been
made to emphasize the treatment capability of the infiltration-percolation
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approach. EPA and its predecessors have been involved in six research
projects having the objective of utilizing the infiltration-percolation
approach to treat municipal effluents for subsequent reuse. Four of
these studies were conducted in the water-short southwestern states
and two were conducted in water-rich north central states.
First, let us consider the objectives and results of the four
studies conducted in the water-short southwestern states. A study
at Whittier Narrows, California was conducted to study the effective-
ness of the infiltration-approach for direct recharge of a potable
groundwater supply with secondary effluent (1) . The results of this
study showed that spreading periods of about 9 hours followed by
drying periods of about 15 hours produced a clear and highly oxidized
water acceptable for recharge at this site. This method of operation
resulted in conversion of almost all applied nitrogen to nitrate and
produced nitrate concentrations in the renovated water two to three
times more than acceptable limits for drinking water. Due to the high
nitrate concentration, it was recommended that dilution with low nitrate
water would be necessary before repumping for use as a water supply.
A concurrent study at Santee, California evaluated the use of
infiltration-percolation to make municipal effluent suitable to fill and
maintain the water level in recreational lakes (2) . Locating the
infiltration-percolation basins in the alluvium of a shallow stream
channel provided substantial lateral movement underground after
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about 10 feet of vertical percolation. In addition to excellent removal
of solids, oxygen-demanding substances, pathogens, and phosphorus,
total nitrogen in the renovated water was reduced to 1.5 mg/1 (from
25 mg/1 applied to spreading basins) after about 1,500 feet of lateral
underground travel. Emphasis was placed on evaluating this nitrogen
removal at a Phoenix, Arizona study using a similar mode of opera-
tion (3). Results of the Phoenix study showed that the frequency of
application has a major influence on nitrogen removal. Spreading and
drying periods of a few days or less promoted nitrification and resulted
in less than 10 percent total nitrogen removal whereas spreading and
drying periods of 10 to 20 days resulted in apparent denitrification
and up to 80 percent nitrogen removal. This study also highlighted
the importance of underground residence time and/or distance of
travel for achieving phosphorus removal at the high loadings used
for the infiltration-percolation approach.
Another important factor related to local hydrological conditions
was graphically demonstrated by a study at Hemet, California (4) . An
unusually wet winter season at this location caused the local water
table to rise up to the bottom of the spreading basins. The resultant
reduction in hydraulic acceptance rate and deterioration of treatment
efficiency made it necessary to quickly develop an alternate method for
handling their effluent.
Now let us look at the results of the two infiltration-percolation
studies in the cool and semi-humid climate of the north central states.
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One of these entailed a four-year experiment using 20-hour spraying
periods followed by 4-hour drying periods to apply about 98 feet per
year of effluent on a sandy soil (5) . Our definitions place this system
in the infiltration-percolation category even though it uses spray
application and is referred to as a spray irrigation system. It is
significant that the use of short spreading and drying cycles in this
climate produced nitrogen and phosphorus interactions comparable to
those for studies in the Southwest. Nitrogen was converted to nitrate
which appeared in the groundwater (at a concentration comparable to
that in a municipal effluent) while 70 percent of the phosphorus was
removed after no more than 20 feet of travel distance through the soil.
The other study in this climate was a one-year evaluation of the perform-
ance of an existing ridge and furrow basin (6) . The system was located
on a silt loam soil and a loading of about 45 feet per year was obtained
with wetting periods of two weeks followed by drying periods of two
weeks. As was the case for the study in Arizona, the long spreading
period resulted in about 70 percent removal of total nitrogen without
affecting the removal capacity for other measured parameters.
Our experiences with the use of the infiltration-percolation
approach to land spreading of municipal effluents are encouraging for
future use on a much larger scale. Technological data are already avail-
able to design and operate systems for a limited number of situations,
but of more importance is the apparent utility of the approach under
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widely differing climatic conditions. We are optimistic that further
research efforts can establish well-defined design criteria and manage-
ment techniques for use throughout the United States.
Cropland Irrigation Systems
Cropland irrigation with municipal effluents is a well-established
practice in the southwestern United States and has been practiced con-
tinuously for over 50 years at many municipalities. This practice has
developed to satisfy a need for more water as well as a need to manage
municipal effluents in an acceptable manner. Utilization of the practice
has grown steadily since the first operations were initiated around 1900,
and there are over 300 active operations at present. In spite of this
impressive number of operating installations, there has been little
research conducted to establish a technological base for predicting the
long-term influence of various management techniques on the crops,
the soils, the groundwater, or the overall ecology cf the area of
influence. EPA is initiating several projects to assess the current
state of our knowledge and to improve management of cropland irriga-
tion systems.
One group of projects is directed to locating and evaluating
currently available quantitative information on application rates, crop
responses, soil changes, and groundwater quality changes from sys-
tems which have been operating for varying periods of time. This
effort should be very useful in defining management techniques for
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general use in the Southwest as well as furnishing a base on which
to build for other geographic locations.
Another group of projects is oriented toward field development
of management techniques for the cooler and more humid regions east of
the Mississippi River. One of these projects has been in operation at
Pennsylvania State University since 1963 (7) . The results of this
project over the first seven years of operation have shown that crop-
land irrigation can be practiced in a cool and semi-humid climate in
a manner that will promote crop production while contributing sub-
stantial recharge to the groundwater. Results reported to date from
the Pennsylvania State University project indicate that an application
rate of 2 inches per week over a 30-week growing season (a total
application of 60 inches per year) is the most beneficial for general
use under conditions existing at this site. The other field development
projects are the Muskegon County Wastewater Management System
currently under construction at Muskegon, Michigan, and a smaller
but similar project just initiated at Belding, Michigan. It will be
several years before field data from these projects will be available
for reliable interpretation and subsequent use in establishing improved
management practices.
Our experience with the cropland irrigation approach to land
spreading stems largely from qualitative information on the perform-
ance of existing systems concentrated in the semi-arid Southwest. In
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general, the performance of these systems has been judged to be satis-
factory; yet there is a general lack of quantitative data to substantiate
this judgment. A carefully managed experimental system located at
Pennsylvania State University has produced quantitative information
over a 7-year period which indicates that cropland irrigation with
municipal effluent can be a practicable wastewater management tech-
nique in cool and semi-humid climates.
Spray-Runoff Systems
The spray-runoff approach has not been utilized for treatment
of municipal wastewaters, but it has been employed at many industrial
plants. Experiences at some of these industrial plants indicated that
spray-runoff had considerable potential for treatment of any wastewater
containing biodegradable organics.
In 1967, our research group at the Robert S. Kerr Water Research
Center initiated a cooperative study with the Campbell Soup Company to
conduct a one-year research study at their Paris, Texas plant. The
objective of the study was to evaluate the performance of the spray-
runoff system at this location which had been in operation for 5 years.
The results of the study on this 3 mgd capacity system showed that the
spray-runoff approach was indeed a very efficient system for removal
of suspended solids, oxygen-demanding substances, and nitrogen
from the cannery wastewater produced at this plant (8) . The results
of this investigation encouraged us to explore the capability of the
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spray-runoff approach for other wastewaters in which biodegradable
organics were the major source of pollutants to be removed by a treat-
ment process. We are currently conducting in-house research to
develop the spray-runoff approach for treatment of raw domestic
sewage and for runoff from beef cattle feedlots. Preliminary results
for both of these wastewaters are very encouraging for development of
practicable systems. For example, the experimental spray-runoff
system we have designed for the treatment of raw comminuted domestic
sewage is producing an effluent that is of tertiary treatment quality
without producing any sludge to handle. The spray-runoff system
designed for treatment of the runoff collected from beef cattle feedlots
has produced equally encouraging performance data. A technical
report covering five months of field evaluation data for the feedlot
runoff system will be available soon.
Technology to utilize the spray-runoff approach for management
of domestic wastewaters is in the rudimentary stage of development.
The exploratory research which we have in progress indicates that
spray-runoff treatment of raw domestic wastewater is feasible but
many more questions must be answered before the process can be
developed for general use.
Summary
The foregoing is a brief summary of the EPA's involvement in
land spreading of municipal effluents for treatment and/or reuse.
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Coverage of the many research projects introduced has, by choice,
been limited and selective in order to highlight the objecti\ *>s of this
presentation. Further information about many of the projects has been
reported in readily available technical publications in addition to those
cited in this paper. For those projects currently in progress at the
Robert S. Kerr Water Research Center of the EPA, the authors can be
contacted to obtain further information.
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TABLE 1
COMPARATIVE CHARACTERISTICS OF SYSTEMS
Factor
Application
Rate
Land Required
for 1 mgd flow
(3.1 ac. ft.)
Application
Techniques
Crop
Irrigation
2 to 8 feet
per year
140 to 560
acres plus
buffer zones
Spray or Flood
Type of System
Spray -Runoff
8 to 15 feet
per year
75 to 140
acres plus
buffer zones
Spray
Infiltration-
Percolation
15 to 400 feet
per year
3 to 75 acres
plus buffer
zones
Usually Flood
Soils
Probability
of influencing
groundwater
quality
Needed Depth
to Groundwater
Fate of
Wastewater
Moderately
permeable soils
with good pro-
ductivity when
irrigated
Moderate
About 5 feet
Pr edominately
evaporation or
deep percola-
tion
Slowly permeable
soils such as
clay loams and
clay
Slight
Not Known
Rapidly per-
meable soils,
such as sands,
loamy sands,
and sandy loams
Certain
About 15 feet
Surface discharge Percolation to
dominates over Groundwater
evaporation and
percolation
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REFERENCES
1. State of California, The Resources Agency, State Water Quality
Control Board, "Wastewater Reclamation at Whittier Narrows,"
Sacramento, CA, Publication No. 33, 1966, 99pp.
2. Merrell, John C. , Jr., Katko, Albert, and Pintler, Herbert E.,
"The Santee Recreation Project, Santee, California," (Summary
Report) , Public Health Service Publication No. 99-WP-27, December
1965, 69pp.
3. Bouwer, H. , "Water Quality Aspects of Intermittent Systems Using
Secondary Sewage Effluent," U.S. Water Conservation Laboratory,
Phoenix, AZ, Paper No. 8, September 1970, 19 pp.
4. Eastern Municipal Water District, "Study of Reutilization of Waste-
water Recycled Through Ground Water," EPA, Water Pollution
Control Research Report Series No. 16060DDZ07/71, Vol. I, July
1971.
5. Larson, Winston C. , "Spray Irrigation for the Removal of Nutrients
in Sewage Treatment Plant Effluent as Practiced at Detroit Lakes,
Minnesota," Algae and Metropolitan Wastes, Transactions of the
1960 Seminar, U.S. Department of Health, Education and Welfare,
pp. 125-129.
6. Bendixen, Thomas W. , et al., "Ridge and Furrow Liquid Waste
Disposal in a Northern Latitude," Journal of the Sanitary Engineer-
ing Division, Proceedings of the American Society of Civil Engineers,
*-
ol.
Vol. 94, No. SA1, February 1968, pp. 147-157.
7. Parizek, R. R. , et al., "Waste Water Renovation and Conservation,"
The Pennsylvania State University Studies No. 23, University Park,
PA, 1967, 71pp.
8. Law, James P., Jr., Thomas, Richard E ., and Myers, Leon H.,
"Cannery Wastewater Treatment by High-Rate Spray on Grassland,"
WPCF Jour.. Vol. 42, No. 9, September 1970, pp. 1621-1631.
225
-------
-------
NATIONWIDE EXPERIENCES IN LAND TREATMENT
by
Charles E. found
Project Manager
Me teal f f, Eddy, Inc.
Palo Alto, California
and
Ronald W. Crites
Project Engineer
Metcalf $ Eddy, Inc.
Palo Alto, California
Presented at the Symposium on Land Disposal of Municipal
Effluents and Sludges, Rutgers University, New Brunswick,
New Jersey.
Preceding page blank
March 13, 1973
227
-------
NATIONWIDE EXPERIENCES IN LAND TREATMENT
Introduction
The information to be presented in this paper is a pre-
view of some of the highlights of a study by Metcalf f, Eddy,
Inc., for the EPA on land application of wastewater. The ob-
jectives of the study were to:
1. Isolate key parameters for design.
2. Evaluate effects on the environment.
3. Determine the risks to health and safety.
4. Evaluate costs.
5. Identify those areas that need additional study.
Historically, the use of sewage effluents for the various
forms of land application lias been termed sewage farming. We
have encountered references to sewage farming as far back as
the 1550's, as indicated in Table 1. It is interesting to note
that some of these systems in the past have covered very large
acreages, some of which are still in existence, particularly
Mexico City which now covers 112,000 acres and disposes of 570
mgd of effluent. The Mexico City installation dates back to at
least 1902 and has grown with the years. Other notable non-
Jnited States installations are Berlin, Germany; and Melbourne,
Australia. In the United States, sewage farming references were
found as far back as 1872. Some of these installations have
'leen abandoned, such as Augusta, Maine; and Pullman, Illinois,
but others are still in existence such as Cheyenne, Wyoming;
and Bakersfield, California. The data shown in Table 1 are for
the initial year unless otherwise noted.
There are three basic modes of land application of waste-
water: crop irrigation, overland flow or spray-runoff, and in-
filtration-percolation. These three modes or approaches to land
application are shown schematically in Figure 1. Irrigation is
the application of water or wastewater to the land to sustain
plant growth. Overland flow consists of spraying wastewater on-
to gently sloping, relatively impervious soil planted to vegeta-
228
-------
Table 1
HISTORY OF SEWAG1- FARMING
to
N5
VO
Date
Location
Wetted Flow, Average Loading
Description area, acres mgd in. /week Reference
N'on -United States
1559
1861
1864
1869
1875
1880
1893
1902
1923
1928
United
1872
1880
1881
1S87
1895
1896
1912
1928
Bunzlau, Germany
Croydon-Beddington, England
South Norwood, England
Berlin, Germany
Leamington Springs, England
Birmingham, England
Melbourne, Australia
Melbourne, Australia
Mexico City, Mexico
Paris , France
Capetown, South Africa
States
Augusta, Maine
Pullman, Illinois
Cheyenne, Wyoming
Pasadena, California
San Antonio, Texas
Salt Lake City, Utah
Bakersfield, California
Vincland, New Jersey
Sewage farm
Sewage farm
Sewage farm
Sewage farm 27
Sewage farm
Sewage farm 1
Pasture irrigation 10
Overland flow 3
£\ age irrigation 112
Sewage irrigation 12
Pasture irrigation
Irrigation
Irrigation
Irrigation 1
Irrigation
Irrigation 4
Irrigation
Irrigation 2
Irrigation
420
152
,250a
400
,200
,376b
,472b
,ooob
,600
3
40
,330d
300
,oooa
180
,400d
14
--
4.5
0.7
150a
0.8
22
50b
70b
570b
120
0.007
1.85
7.0d
--
20a
4
11.3d
0.8
--
2.8
1.2
1.4
0.5
4.7
1.2
5.2
1.3
2.5
—
0.6
12.0
1.3
--
1 ,3
5.7
1.2
14.7
1
•>
2
2
5
3
4
4
5
2
6
7
7
5
2
2
7
8
a. Data for 1926.
I). Data for 1971.
c. Abandoned around 1900.
d. Data for 1972-.
-------
EVAPORATION
SURFACE
APPLICATION
ROOT ZONE
SUBSOI L
SLOPE VARIABLE
-DEEP
PERCOLATION
SPRAY APPLICATION —
SLOPE 2-6 -
a) IRRIGATION
EVAPORATION
GRASS AND VEGETATIVE LITTER
SHEET FLOW
pfSc°uY,ON
I 7ri 300 FT
b) OVERLAND FLOW
RUNOFF
COLLECTION
28ȣ OF AERATION
ftttO T8Ut«t«t
SPREADING BASIN
SURFACE APPLICATION
THAOtlGI*
UBSATilftATEO ZONE
«(!«».«»«£
NB \ -*^:::::::::::::::::::nV / k
V ^^•^••i*' %•••"•••**••••••.•*»••• ^^^ J
^i •rr-»J'».r.T** jttTyif !1"'" --••------ "^^">f • " ' 1^^., . W '
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Hit
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iiiiiiiiiiiiiiiiiiiiiiiiiliiiiimhii
«**••*•••**•••••••***••••• • * | ».* •<»• « • •.••.•.••*••• .^ *••• .*f>.I.|«i>.*.*. «\* •••••••••• *T*TV*«A* * •••••••••^••••••••"••••••* »1^ ^
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1***.""!"!*^!""t!!!I*"i!!Z!!"!*.!*.!!!!!i2!!!!C" tl. !»*IZ!Ctt mZl*\*m*!tC*C t •!!!!!! II Z!*!"*!*.**.**!!*;;3F!*"
":::::;::n::::::::::;i;:;;;ii:!i:;:::;::K!::::::::ft:^:H;;:;!::::?i<::::::::::i;;::^ /
OLD WATER TABLE
c) INFILTRATION-PERCOLATIOM
FIGURE 1
LAND APPLICATION APPROACHES
-------
tion. Biological treatment occurs as the wastewater trickles
through the vegetative litter and contacts the biota. In-
filtration-percolation is the application of water or waste-
water to the land with nearly all the water infiltrating the
surface and percolating through the soil pores. Many factors
are pertinent to the design and operation of all three modes,
the two most important categories being site and wastewater
characteristics.
Site Characteristics
Site characteristics include such items as climate, top-
ography, soil type, underdrainage, and groundwater. Climate
is most important in the design and operation of irrigation and
overland flow systems as it affects crop growth and net micro-
bial activity in and on the soil Topography may dictate the
method of application such as spraying as opposed to the ridge
and furrow or flooding techniques. Soil types may dictate the
type of cover crop, method of application, and the mode of
application. For example, a sandy soil may be suitable for
Infiltration-percolation systems whereas a tighter loam soil
would be suitable for either overland flow or crop irrigation.
Underdrainage involves soil structure, texture, and depth, as
well as underlying geological formations. Drainage is a key
parameter in determining hydraulic loading rates, Groundwater
is important both in its level and movement as it affects the
hydraulic and renovative capacity of the system end in its
quality.
Wastewater Characteristics
Municipal wastewater characteristics may be classified as
physical, chemical, and biological. In land application, impor-
tant physical characteristics are suspended solids content, temp-
erature, and odor. Suspended solids can clog sprinkler heads
and can be a limiting factor in the design of infiltration-per-
*
eolation systems. Temperature is not a great problem for munici-
pal wastewater because it has a fairly even temperature, SO deg.
F.to 70 deg. F, which is not harmful to soil or vegetation.
Odors, caused by decaying organics, can be reduced by maintaining
231
-------
aerobic conditions throughout the system.
Chemical characteristics include organic matter and dis-
solved inorganics. Organics are measured as BOD or COD and
are important in that they are trapped and decomposed on or
in the soil. The biological characteristics of municipal
wastewater are chiefly bacteria and viruses.
The important wastewater parameters in the design of land
treatment systems are organic and nutrient loads, particularly
the nitrogen application, because of possible contamination of
the groundwater or surface water with nitrates. The chemical
constituents are important because they may produce a salinity
buildup both in the groundwater and in the upper soil layer,
resulting in toxicity to the cover crop. Specific ion toxicity
such as boron and one or more heavy metals may also be a prob-
lem. Boron may adversely affect some plants at concentrations
as low as 0.5 mg/L. Metal ions such as sodium, calcium and mag-
nesium, which are part of the sodium adsorption ratio, are also
important because if this ratio exceeds 15 in clay-type soils,
there may be a total sealing of the soil surface. Bacteria and
virus are important from a public health standpoint, particular-
ly the possibility of contaminating groundwater and edible
crops .
Irrigation
Irrigation is the most widespread and well developed of the
.and application modes. It is practiced throughout the nation
out most heavily in California, Arizona, New Mexico, and Texas.
".his discussion will cover briefly the items of design, manage-
ment, health aspects, and costs for forest, landscape, and crop
irrigation.
Design. In considering design criteria for crop irrigation with
municipal effluents, two particular points are important: load-
ing rates and cover crops. In addition, all of the techniques
standard to agricultural irrigation practices must also be con-
sidered. Some loading rates versus soil types and crops, that
were encountered in a literature survey or in site visits, are
listed in Table 2. Loading rates are given in inches of effluent
232
-------
Table 2
LOADING RATES VERSUS SOIL TYPE AND CROP
City
Loading
rate
in. /wk
Soil type
Crop
Heavy application > 7 in./wk
Vineland, N.J.
figlin AFB, Fla.
Dinuba, Calif.
Quincy, Wash.
12-°b
11.2°
10. 5a
7.2
Sand
Sand
Silt , sand
Silty sand
None
Forest
None
Corn, wheat
Moderate application > 3 in./wk < 7 in./wk
Hanford, Calif.
Tallahassee, Fla.
Lake Havasu, Ariz.
San Bernardino, Calif.
Ilillsboro, Ore.
4 2a
* K
4.0b
K
3'8b
3'7b
3.2b
Sandy loam
Sand
Sand, gravel
Sand
Sandy loam
Corn ,oats , cotton
Corn , millet ,
sorghum, grass
Grass
Grass
Grass , forest
Light application < 3 in./wk
Abilene, Texas
Alamogordo, New Mexico
Plcasanton, Calif.
Hly, Nevada
Rawlings, Wyoming
Baktrsfield, Calif.
3.0a
0
2.5a
K
2.2°
1 . 7
1.5a
1.2a
Clay loam
Loam, silt ,
clay
Loam
Sandy loam
Gravel
Clay loam
Cotton, maize ,
coastal bermuda
grass
Corn , oats ,
sorghum, alfalfa
Grass
Alfalfa
Alfalfa
Cotton, corn,
barley, alfalfa
a. Surface irrigation
b. Spray irrigation
233
-------
applied per week and include a single complete cycle o I"
wetting and drying.
Table 2 has been divided into three hydraulic application
rate classifications: heavy, moderate, and light. The listings
in the heavy classification range from about 12 in./wk down
to 8.4 in./wk; those in the moderate classification range from
4.2 to 3.2 in./wk; and those in the light classification range
from 3 in./wk down to 1.2 in./wk. As one might suspect, the
heavy applications were without exception found in soil types
consisting essentially of sand and application rates were lower
as the soil types became finer in texture. Further, the heavy
applications in the sandy soils were done in some cases without
cover crops whereas all of the heavier soils required cover
crops in order to enhance the application rates and, in most
cases, offset a part of the operating costs of the irrigation
system.
Hydraulic loading is usually critical. However, where
water is applied at such rates thai it will percolacc through
the soil matrix into the groundwater, nitrogen loading may be-
come the most critical loading parameter. Considering an efflu-
ent with 20 mg/L of total nitrogen applied at a rate of 3 in./wk,
the nitrogen loading would be approximately 680 Ib/acre/yr.
Even if 30 percent of this nitrogen were nitrified and then de-
nitrified and lost to the atmosphere, there would still be approx-
imately 480 Ib/acre/yr remaining to be taken up b/ the crop.
Some nutrient uptake rates by several selected crops are
listed in Table 3. Coastal bermuda grass appear.; to be a large
user of nitrogen and would take up sufficient nitrogen to satisfy
the example just illustrated. In some parts of the country it is
possible to double and even triple crop, but nonetheless there
is a limit to the amount of nutrient uptake by crops. During our
survey we have noted loadings from 15 to 1,500 Ib/acre/yr of
nitrogen with a median vaiue of approximately 120 Ib/acre/yr.
Management. Management of a crop irrigation system must be such
that removal efficiencies of wastewater constituents are suitable
234
-------
Table 3
CROP UPTAKE OF NUTRIENTS
Crop
Alfalfa
Coastal berrauda grass
Corn
Red clover
Reed canary grass
Soybeans
Wheat
Uptake, Ib/acre/year
Nitrogen(N)
155-220
480-600
155
120
226
99-113
62-76
Phosphorus (P)
16-21
35
25
12
36
14-18
12-14
Reference
9
10
9
9
11
9
9
235
-------
for the particular conditions. Some typical removal efficien-
cies reported in the literature are shown in Table 4. These
numbers should not be compared to each other because each one
has a particular set of conditions, including various applica-
tion rates, soil types, and depth of measurement. Also, some
represent removal efficiencies based on secondary treatment
and others on primary treated or untreated wastewater. Never-
theless, it can be seen that with application rates of 4 in./wk
or less, very high removal efficiencies can be expected at soil
depths of 3 to 6 ft as suggested by the Penn State and Melbourne,
Australia, references. It is interesting to note that with lower
hydraulic application rates, a higher removal of nitrogen can be
obtained. This is because the nitrogen loading approaches the
nutrient uptake levels of the crops or forage being irrigated.
Even at high hydraulic loading rates, the BOD removal rates are
normally above 95 percent and nitrogen removals will be 50 per-
cent or better except in coarse grain sands.
Monitoring of a system that Is being used for wastewater
irrigation is a must. Although crop irrigation has been used
for centuries for the treatment and disposal of wastewaters,
there is still much to be learned about the effects of waste-
waters on soil, vegetation and underlying groundwaters. Some
of the reasons for monitoring include identifying fl) salt build-
up in the upper layer of soil which may become toxic to vegeta-
tion, and (2) leaching of salts into the underlying groundwater
body which may contribute to excessive TDS in driiiKing water sup-
plies. Also, monitoring will provide the necessa.'y management
tools for determining rest periods for particular plots as well
as the addition of fertilizers or soil amendments that may be
needed to perpetuate the use of the land for wastewater irriga-
tion.
Insect problems are a definite management problem in crop
irrigation systems. Several industrial installations in Cali-
fornia were in acceptable positions with the water quality con-
trol agency but were in conflict with the Mosquito Abatement
Districts. All efforts must be taken to prevent standing ponds
236
-------
Table 4
REMOVAL EFFICIENCY AT IRRIGATION SITES
Location
r\
Lake Tahoe
West by ,
Wisconsin
Cincijinati
(sand)
Cincinnati
(silt Loam)
Cincinnati
Ponn State0
Melbourne6
Estimated
Removals
Load ing
Rate,
in/wk
13.4
11.2
11.2
11 . 2
11.2
4.0
1.3
2.0
Removal Efficiency, %
BOD SS N P E.Coli.
56 91 96b
88 -- 70 93
95 -- 20 30
95 -- 50 96
85 99
98 99 91 99 99
98 97 90 80 98
99 99+ 80-90 99 99
Reference
12
13
13
13
14
15
16
17
a. Data on runoff during 1964, operation ceased in 1968
b. Removal from chlorinated secondary effluent
c. Removals from secondary effluent at 3 ft. depth.
d. Experimental outdoor lysimeters 6 ft. deep at Taft
Sanitary Engineering Center.
e. Removals from raw wastewater at 4-6 ft. deplh.
f. Estimated for ideal conditions.
237
-------
of water that will contribute to the propogation of mosquitoes
and other insects.
Health Aspects. Public health aspects of wastewatcr treat-
ment and disposal systems cannot be overlooked. This is par-
ticularly true in crop irrigation systems where edible crops
are grown or where livestock are grazing on the field. Some
of the survival times of various organisms on different media
are listed in Table r. Th Ascaris ova probably have the long-
est survi- '1 time in soil, reported up to seven years. However,
the remainder of those organisms most usually associated with
waterborne problems fall within 70 days and many of them less
than 30 days. It is interesting to note that the Ascaris ova
on vegetables have a survival time of 27 to 35 days whereas in
the soil they may persist up to 7 years. To some degree this
can also be noted on the B_. typho_s_a_, Hndamoeba histolytica, and
Salmonella typhi. It appears tiiat the environment above ground
is more harsh than in the soil. Nevertheless, care must be
taken to disinfect the effluent prior to application to any
form of crops or vegetables that may be for human consumption.
In California the present requirement is 2.2 coliforms per hun-
dred ml for unrestricted irrigation with wastewaters.
Costs. Capital and operating costs for crop irrigation with
municipal effluents are difficult to obtain and are not necessa-
rily comparable to each other. For instance the capital cost
'"or crop irrigation in Bakersfield, as shown in Table 6, is
Li$ per gpd of plant capacity and in Ephrata, Washington, is
47
-------
Table 5
SURVIVAL TIMliS OF ORGANISMS
Organism
Ascaris ova
B. Typhosa
Cholera vibrios
Coliform
Endamoeba
histolytica
Hookworm larvae
Leptospira
Polio virus
Salmonella
typhi
Sh.gella
Tubercle bacilli
Typhoid bacilli
1 Typo of
Me d L urn App 1 i ca t i o n
Soil
Vegetables
Soil
Vegetables
Spinach, lettuce
Non-acid vege-
tables
Grass
Tomatoes
Vegetables
Soil
Soil
Soil
Polluted water
Radishes
Soil
Tomatoes
Soil
Soil
;
Sewage
ACa
AC
AC
AC
AC
Sewage
Sewage
AC
AC
Infected
feces
AC
Infected
feces
Infected
feces
AC
AC
AC
Survival
T i me
up to 7 yr
27-35 days
29-70 days
31 days
22-29 days
2 days
14 days
35 days
3 days
8 days
6 weeks
15-43 days
20 days
53 days
74 days
2-7 days
6 mos .
7-40 days
Re fe rcnce
18
19
19
19
18
18
19
19
19
18
18
18
19
18
18
18
18
19
a. AC = Artificial Contamination.
239
-------
Table 6
CAPITAL AND OPERATION 'COSTS
MUNICIPAL IRRIGATION SITES
Year
Started
City
J 972 Capital Cost'
Flow,mgd
Cost'
$/mg (jr/1000 gal
1957 Oceanside, 1.5
California
1966 St. Charles, 0.5
Maryland
1957 Pleasanton, 1.3
California
1935 Golden Gate 1.0
Park, San
Francisco ,
Cali fornia
92
19
27
116
87
74
70
11.6
8.7
7.4
7.0
1953
1972
1959
1912
1908
1933
1965
Colorado
Springs ,
Colorado
Ephrata,
Washington
Santee
Cali fornia
Bakers field,
Cali fornia
Ely, Nevada
San Angelo ,
Texas
Calabasas ,
Cali fornia
5
0
1
12
1
5
3
.5
.44
.0
.3
.5
.0
.0
24
47
4
21
11
4
23
69
68
66
48
40
30
27
6
6
6
4
4
3
2
.9
.8
.6
.8
.0
.0
.7
a. Capital improvements made from initial year to 1972.
b. Based on 1972 budget.
240
-------
somewhere between 6 and 7$ per thousand gallons. The figures
were based on the 1972 budgets from each of the facilities listed.
All installations listed in Table 6 use spray irrigation, ex-
cept Bakers field as noted above, Ely, Nevada, and San Angelo,
Texas which use flood irrigation.
Overland Flow
Although overland flow has been used in several industrial
applJ ations throughout the country, there are no -known appli-
cations of tills approach with municipal effluents within the U.S.
Melbourne, Australia has used this mode successfully and it is
presently under study at EPA's research center at Ada, Oklahoma.
Several articles have been written on the overland flow system
for cannery wastewater at Paris, Texas. The climatology, micro-
biology, hydrology, and agricultural aspects of that installa-
tion have been studied (11,20). At Melbourne, Australia a load-
ing rate of 5.2 in./wk Is used during the 6 month operating
period. Italian rye grass is used and ropor^^d removals are
BOD 96 percent, suspended solids 95 percent, detergents 50 per-
cent, total nitrogen 60 percent, total phosphorus 35 percent,
and E. Coli 99.5 percent (16). This mode appears to have con-
siderable potential for municipal wastewater treatment, but needs
development.
Infiltration - Percolation
This mode of application has been successful as a means of
groundwater recharge, examples of which are Phoenix, Arizona and
Hemet and Whittier Narrows, California. Difficulties with these
installations have involved the high nitrate concentrations in
groundwater which have either required dilution with higher qual-
ity water or will eventually call for improvements in pretreat-
ment or modifications in the hydraulic loading cycle.
This method has also been used for disposal without consid-
eration of groundwater recharge.* Three installations utilizing
high application rates are located at Lake George, New York;
Detroit Lakes, Minnesota; and Vincland, New Jersey. Lake George,
New York, applies approximately 7 to 15 in./wk to percolation
241
-------
beds constructed over a sandy stratum of soil. Ice and snow
have not produced any difficulties because the ice simply floats
on the water as it is applied to the spreading basin. Detroit
Lakes, Minnesota, applied approximately 42 in./wk and Vineland,
New Jersey, applies about 12 in./wk. Lower rate applications
of wastewater for disposal using the infiltration-percolation
mode can be found at Orland and Kingsburg, California, using
rates of 2.2 in./wk and 1.5 in./wk, respectively.
Modifications of the infiltration-percolation procedure
are being considered at Flushing Meadows near Phoenix, Arizona,
in which effluent would be introduced into the ground by infil-
tration-percolation and then withdrawn by pumping (21) . The
soil in this case would be used as a filter and thi withdrawn
waters would be used for agricultural purposes. The remaining
nitrogen would be no problem because of this ultimate use.
242
-------
REFERENCES
1. DeTurk, E. E., "Adaptability of Sewage Sludge as a
fertilizer, "Sewage Works Journal, 7_, No. 4, pp. 597-
610 (1935).
2. Mctcalf, L., and Eddy, H. P., American Sewerage Practice,
Vol. Ill, Disposal of Sewage, 3rd Ed., pp. 233-251, McGraw-
Hill Book Co., New York (1935).
3. Rafter, G. W., "Sewage Irrigation," USGS Water Supply and
Irrigation Paper No. 3, Dept. of the Interior, Washington,
D. C. (1897).
4. Melbourne and Metropolitan Board of Works, "Waste into
Wealth," Melbourne, Australia (1971).
5. American Public Works Association survey (1972).
6. Center for the Study of Federalism, Green Land -- Clean
Streams: The Beneficial Use of Waste Water Through Land
Treatment, Stevens, R. M., Temple University, Philadelphia,
Pennsylvania (1972).
7. Rafter, G. W., "Sewage Irrigation, Part II," USGS Water
Supply and Irrigation Paper No. 22, Dept. of the Interior,
Washington, D.C. (13.19).
8. Mitchell, G. A., "Muiicipal Sewage Irrigation," Engineering
News-Record, 119, pp. 63-66 (July 8, 1937).
9. Fried, M. , and Broes'iart, H., The Soil-Plant System in Rela-
tion to Inorganic Nutrition, Academic Press, New York (1967),
10. Personal communication, J. Neal Pratt (1973).
11. C. W. Thornthwaite Associates, "An Evaluation of Cannery
Waste Disposal by Overland Flow Spray Irrigation," Publica-
tions in Climatology, 22, No. 2 (September, 1969).
12. Foster, H. B., Ward, P. C., and Prucha, A. A., "Nutrient
Removal by Effluent Spraying," ASCE San. Engr. Div. , 91,
No. SA 6, pp. 1-12, (1965).
243
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13. Bendixen, T. W., et al., "Ridge and Furrow Liquid Waste
Disposal in a Northern Latitude, " ASCE San. Engr. Div. ,
9_4, No. SA 1, pp. 147-157 (1968).
14. Schwartz, W. A., and Bendixen, T. W. , "Soil Systems for
Liquid Waste Treatment and Disposal: Environmental Factors,"
Jour. WPCF, 4_2_, No. 4, pp. 624-630 (1970).
15. Parizek, R. R., et al., "Waste Water Renovation and Conser-
vation," Penn State Studies No. 23, University Park, Penn-
sylvania (1967).
16. Kirby, C. F., "Sewage Treatment Farms," Dept. of Civil
Engineering, University of Melbourne (1971).
17. "Wastewater Management by Disposal on the Land," Corps of
Engineers, U.S. Army, Special Report 171, Cold Regions
Research and Engineering Laboratory, Hanover, N. H. (May,
1972).
18. Dunlop, S. G., "Survival of Pathogens and Related Disease
Hazards," Proceedings of the Symposium on Municipal Sewage
Effluent for Irrigation, Louisiana Polytechnic Institution
(July 30, 1968).
19. Sepp, E., "The Use of Sewage for Irrigation—A Literature
Review," Bureau of Sanitary Engineering, California State
Department of Public Health (1971).
20. Gilde, L. C., et al., "A Spray Irrigation System for Treat-
ment of Cannery Was^s," Jour. WPCF, 43, No. 8, pp. 2011-
2025 (1971).
21 Bouwer, H., Rice, R.C., and Escarcega, E. D. , "Renovating
Secondary Sewage by Groundwater Recharge with Infiltration
Basins," U. S. Water Conservation Laboratory, Office of
Research and Monitoring, Environmental Protection Agency,
Project No. 16060 DRV (March 1972).
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A SURVEY OF
LAND APPLICATION OF WASTEWATER FACILITIES
Richard H. Sullivan, Assistant Executive Director
American Public Works Association
The American Public Works Association in 1972 conducted a
field survey of 100 facilities where land application of domestic
or industrial wastewater effluents were applied to the land, as
contrasted to the conventional method of discharging such effluents
to receiving waters. In addition, an extensive bibliography was
compiled (to be published separately); data were gathered from many
other existing land application facilities across the country;
determinations were made as to state regulations governing the use
of land application facilities; and a survey was made of experience
gained in many foreign countries.
The facilities surveyed were relatively large, with long-
established operations in order that as much viable operating
experiences as possible could be obtained. The surveyed land
application facilities utilizing domestic wastewaters were
predominantly located in the western and southwestern portions of
the nation, while industrial facilities were generally sited in
the northeastern section, because this is where the majority of such
installations are in service.
Agricultural wastes facilities and evaporation-percolation
or spray runoff type facilities were not included in the investigation
project.
A full report is being prepared as fulfillment of Contract
68-01-0732 from the U. S. Environmental Protection Agency and will
be available in the Summer of 1973.
Presented at a Symposium on Land Disposal of Wastes, Rutgers' University,
March 13, 1972.
245
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The practicability of the application of sewage and wastes
effluents onto land areas rather than directly into water sources
is dependent, as are other moans of treatment, upon complex and
interacting circumstances and conditions.
This "alternative" method of disposing of wastewaters which
could affect the q\iality and usefulness of surface waters, or require
advance degrees of treatment to prevent such adverse effects on the
water environment, has been under intensive'and extensive study and
evaluation, particularly in recent years.
The basis for acceptance of land disposal, or "sewage
farming," as described at the turn of the century, by M. N. Baker
in his historic pamphlet, "Sewerage and Sewage Disposal," a page
of which is shown in Figure 1 is no longer adequate to meet new
approaches to, and concepts of, land application systems. The
•
propriety of this process has been investigated to demonstrate its
applicability to the clean-waters criteria of the 1970's and the
economic, ecologic and effectiveness factors involved.
The study by the American Public Works Association is one
of the several investments of scientific time and funds to put the
land application process into proper perspective with so-called
conventional methods of discharging effluents of varying degrees
of purity into watercourses.
It is apparent that any decisions to utilize effluent land
application methods, in lieu of treatment and discharge of high
trade effluents into surface waters, must be based on facts which
will establish the process as the best alternative "practicable
waste treatment technology" and one which will provide effective
disposal "over the life of the works," in consonance with the intent
of the Federal Water Pollution Control Act Amendments of 1972.
Decisions thus arrived at must involve consideration of the factors
covered by the current study.
246
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Figure 1
SEWL-RAC-E AND SI-WAGE PUKIMCATION
by
M.N. Baker. I'll. B. C.E.
Associate lulitor, "Engineering News"
Broad Irrigation or Sewage Farming
Where sewage is applied to the surface of
the ground upon which crops are raised the
process is called broad irrigation, or sewage
farming. The practice is in most respects
similar to the ordinary irrigation of crops with
clean water, the sewage being applied by a
variety of methods, according to
topographical and other natural conditions
and the kind of crops under cultivation,
The land employed for this method of
purification should preferably be composed
of a fairly light, porous soil. The crops should
be such as require, or at least develop best
under a large amount of moisture. Where the
soil is heavy and wet. and the crops cannot
stand much water, the sewage must be applied
sparingly, and so a large amount of land and
much labor must be provided. As broad
irrigation areas may. be prepared at
comparatively small expense it is sometimes
feasible to make use of land not so well suited
to the purpose as might be desired, provided
it can be obtained cheaply enough and too
much stress is not laid upon the raising of
crops. The less the attention paid to cropping,
generally speaking, the greater the amount of
sewage which can be put on a given area of
land. Wet, clayey soils can take but little
sewage under any circumstances, but
sometimes improve with cultivation and the
application of sewage.
The application of an average of from
5,000 to 10,000 gallons of sewage per day to
one acre of land is considered by many as a
liberal allowance. On the basis of 100 gallons
of sewage per head of population this means
that one acre of land is sufficient for a
population of from 50 to 100 persons. More
could be purified if the crops would stand it,
but for each kind there is a limit which if
passed means the destruction of the crop.
Allowing even 10,000 gallons of sewage,
or 100 persons, to an acre in a city of 20,000
inhabitants would require 200 acres. To find
suitable land at a low price near cities is not
always easy. The larger the city the greater
the difficulty. Labor, too, is a big item in
sewage farming on this side the Atlantic,
especially near cities. As a partial offset to
th.s, great cities afford excellent and
never-failing markets. Another great obstacle
to adequate financial returns from sewage
farming in America is the deplorable fact that
political ends and not business principles
govern in large numbers of our cities, though
there is good reason to predict a great change
in this respect ere long. Where such conditions
do prevail, however, the positions of both
superintendents and laborers on sewage farms
are almost sure to be considered rewards for
and encouragements to party service, with
results most unfavorable to the enterprise in
hand. Sewage farming means the selling as
well as the raising of crops, and perhaps of
live stock, and so requires business ability and
agricultural skill. The latter must be
accompanied with the faculty of handling
considerable bodies of men.
These apparently discouraging statements
are meant rather as warnings. They are
necessary because of the glowing
representations which have been made
regarding the profits of sewage farming by
those who have not looked at all sides of the
question. 1 am not unmindful of the results of
sewage farming abroad, but European
conditions arc far different from ours. Many
of the European farms are most admirably
managed, both from an agricultural and
business standpoint, and not a few of them
have to contend with soil far less favorable
than could be found in many sections of the
United States. 1 do not say that an American
city could not conduct so great an enterprise
in a creditable manner, for we have found
many well-conceived and well-operated
municipal works of great magnitude. I do viy
247
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that high prices for land near largo cities.
costly labor, a constant warfare against
corruption with loo frequent surrenders, and
our sudden and complete changes in
government all make sewage fanning more
difficult here'than abroad.
For the' present, sewage disposal cannot
be accomplished in this country at a profit. It
is sometimes possible to regain, through the
raising of crops, a part of the expense entailed
in removing and purifying sewage, and this is
the only method by which any considerable
portion of the expense has yet been recovered
here or elsewhere. We should be thankful for
the day of small things, and wherever a
revenue can be obtained from irrigation area
or filtration beds our efforts should be to
secure it. But the logic of figures will often
show that some method of disposal that
carries with it no financial. returns is the
cheapest, in which case instead of crying over
spilt and wasted sewage, we may laugh over a
saving in capital, interest and maintenance.
Wherever irrigation, pure and simple, that
is the application of water to crops for the
sake of moisture, can be practiced to
advantage, sewage farming should receive
serious consideration, for in such localities
every drop of water is valuable. As ordinary
irrigation may yet be used in the East as well
as in the West, (it is already practiced to some
extent in the South) the use of sewage for
mere watering as well as fertilizing may some
day be seen here and there throughout the
length and breadth of the land. This is a
subject which demands careful investigation
and perhaps might be taken up with
advantage by some of our agricultural
experiment stations and by any live official in
a position to do so.*
Tor an article on "The Use of Sewage for Irrigation in the
West" see Kngineering .\ews for Nov. 3. 1S92: the substance
of the article is also ci\t'ii in Kjfter and Baker's "Sewage Dis-
posal in the United St.ites." A later treatment of the subject
may be found in "Sew.ue Irrigation." Nos. 3 and 22 of \\ater
Supply and Irrigation I'apers of the U.S. deolnficul Survey,
by Ceo. W. Kafter. M. Am. Soc. C.L. In March. 1905. the
author of this book \Wted tho sewage farm of Pasadena. Cal.,
and also land to which borne of the sewage of Los Angeles is
applied. As a result, he is mure than ever coiuinced of the
wisdom of using sevsjge for irrigation wherever water is
scarce.
248
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There is nothing new about the basic concept of spreading
sewage or other liquid wastes, in treated or untreated form, on
the land as a means of disposal. What is new is the objective of
making this method of disposal a scientifically evaluated,
technically designed, and properly operated and maintained
treatment procedure which can meet the criterion of a "best
practicable technology." Also of relatively new significance is
the more specific definition of land application as referring to
the application of effluents onto land areas after degrees of
treatment approaching those normally required for effluents
dischar£ed to receiving waters. The application of sludges of
wastewater residues to land areas is a supplemental ramification
of effluent land application.
Land application of sewage predates any known artificial
means of treating liquid wastes prior to discharge into receiving
waters. Even though early practice involved the disposal of
untreated wastes onto farm properties, it had the merit of
providing the "purification" which absorption, adsorption and
mechanical retention on soil particles and in their interstices.
could accomplish. It was better than discharge by dilution into
watercourses.
Actual application of sewage to the land can be dated back
to periods prior to the development of sewer systems. Municipal
wastes were discharged onto nearby farms at Berlin, Germany, as
far back as the 16th century. In Scotland, fields in the vicinity
of Edinburgh were used as the recipients of sewage in the 1840"s;
Berlin purchased tracts of land for sewage irrigation purposes in
1869 and various English communities utilized farm lands for sewage
farming during the last three decades of the nineteenth century.
With the turn of the century, United States cities in Wyoming,
Utah, Montana and California applied sewage to farm lands for crop
improvement or groundwater supplementation. In Texas, San Antonio
initiated irrigation with sewage or sewage effluent on over 3,000
249
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acres of land in 1900. The use of some form of treated effluents
for land disposal purposes, rather thnn raw sewage application,
dates from the 1930's. A land irrigation system using untreated
sanitary wastes of the City of Mexico City D.F. was begun in 1902
and expanded to the use of secondary effluent for watering farm
lands, sport areas and creating artificial lakes in recent years.
Among the other cities surveyed for this report, 10 were established
before 1920 and 10 more by 1940, with 26 municipal systems begun
since 1960.
If land application of effluents is a valid alternative
method of wastes treatment, it is obvious that it is an alternative
to other means of disposal. Land application decision must not be
selected without full evaluation of its merits, economically,
ecologically and effectively, as compared to other means of disposal.
Such an evaluation is presupposed by the requirements of the 1972
Amendments to the Federal Water Pollution Control Act. It involves
a weighing of the advantages and limitations of each method of
disposal in relation to the other alternatives, and the examination
of the comparative merits of each.
I hope to focus attention on some of the general factors
involving land application which must be balanced in determining
the applicability of land application management procedures.
If land application is an alternative procedure, the reasons
for utilizing this technique offer various alternatives: (1) as a
means of disposal without the necessity of constructing outfall lines
to distant water courses—the get-rid-of procedure; (2) as a means
of improving the effluent by natural soil treatment and thereby
avoiding the necessity of advanced treatment by conventional
"artificial" processes; (3) as a means of augmenting the groundwater
table; or (4) as a means of irrigating crops and improving yields
in agriculture or silviculture. The land application installations
investigated during the course of the current study cover examples
250
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of all these reasons for this method of effluent management, as
well as other more or less valid purposes.
The ability of soil to remove organic pollutants by
mechanical, physical and biological forces has been utilized in
conventional sewage treatment methods, in the form of sand filters.
Obviously, there is a direct relation between the artificial use
of soil-wastewater contacts for treatment purposes and the application
of effluents to natural land areas to "get -rid of" wastewaters and to
utilize the purifying capabilities of the soil to provide a form of
physical-chemical-bacteriological improvement of quality.
Those early land disposal installations which applied
untreated or only partially treated wastes to land areas were
depending on the purifying capabilities of the land to provide "free"
treatment. Today's concept of land application--and the basic
definition of land application as investigated under the terms of
the current contractual studies--involves the application of treated
effluents, of proper quality to assure the protection of the surface
environment, groundwater, the use of crops grown on irrigated land,
and the health and safety of on-site and off-site persons.
The movement of water on and through soil formations is a
complex physical reaction which involves chemical-physical-
biological reactions. Under proper soil conditions and control
measures, improvement in water quality can occur during this movement.
It can produce an effluent end product that is of markedly higher
quality than the applied wastewater which has received the equivalent
of secondary treatment by pre-irrigation means. This improvement is
one factor that must be weighed in evaluating the applicability and
workability of land application versus advanced degrees of treatment
by other means.
The ability of soils to remove a major percentage of the
nutrients in sewage effluents has led to the advocacy of land
application as an anti-eutrophication procedure. If the transfer of
effluent discharge from waters subject to nutrification and algal
251
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stimulation resulted in the mere shift from nitrates and phosphates
in surface waters to their presence in groundwaters, less value
could be attributed to land application methods. However, the
mechanics of soil uptake and the utilization of such nutrients by
plant life offers advocates of land application the valid argument
that an ecological liability can be converted into an agriculutural
asset.
Similarly, the uptake of other potentially deleterious
substances in effluents by soil mechanics represents another factor
which must be weighed in placing land application in proper perspective
with other methods of effluent management. These could include
metals and chemical components which can be absorbed or adsorbed in
or on soil particles or ingested by plant life. However, the effect
of such chemicals on the soil composition and friability and filter-
ability, or on the safety of crops grown on such soils, must be
considered.
References to the mechanics of soil management of effluent
liquids and their quality improvement must be augmented by a brief
comment on what has been defined as a "4-R cycle"—Return;
Renovation; Recharge; Reuse. Liquid wastes are returned to the
land by alternative means, including rapid filtration, spray
irrigation, and other means of surface spreading. Irrigation can
be accomplished by spray application, ridge and furrow flows and
flood spreading.
Surface soil layers renovate the effluent by removal or
conversion of pollution materials. The improved liquid is then
used to recharge the groundwater. The renovated liquid is reused.
The land application process offers the possibility of
meeting the conservationist goal of "returning to the soil that
which came from it." The nitrogen cycle and the carbon'cycle
involve land in the completion of their reduction-oxidation-
reconstitution sequences. If the organics in wastewaters and the
chemicals of vegetative value, together with other exotic
252
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substances such as hormones, could be utilized to grow food from
which the organics and other elements originally stemmed, the recycle
of these materials by means of land application would be achieved.
For example, the reuse in the "4-R" concept described above, involves
the reuse of not only the water component of waste effluents but
the nutritive composition of the liquids and trace elements therein.
The land application technique, as an alternative effluent
management procedure, must be placed into proper focus with other
frameworks than specific engineering, technology and economics.
The effect of setting aside large acreages for effluent application
or the dislocation of farm dwellers must be considered as a
sociologic-demographic problem of significance. The impact of land
application on land use planning, zoning and long-range metropolitan-
regional development must be considered. The effects of aesthetics
are part of any thorough ecological evaluation of this alternative
method of effluent disposal. Health and safety impacts must be
considered.
Comparative costs of the various means of handling effluents,
after suitable stages of treatment of municipal and industrial
wastewaters, are difficult to compute and evaluate. They depend on
such variable factors that no rule-of-thumb can claim to represent
fiscal factors involved in any one specific project. These
comparative costs must be placed into perspective with the goal of
all-out elimination of pollutional discharges into the nation's
water sources, whether it be by degrees of advanced treatment which
will provide "zero pollution" in direct effluent discharges, or the
elimination of direct discharges by means of such alternative practices
as land application.
No single answer could possibly become the panacea for all
pollution control challenges in all areas. What may be the best and
most economical solution for one region, one specific location, one
actual wastewater flow, cannot be assumed to be the answer for another,
even if superficial similarity can be found.
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The following highlights from the field surveys is presented
in order that a composite picture of observed facilities might be
obtained:
1. Communities generally use their land application
system on a continuous basis. Food processing
plants, the predominant industrial users of the
system, generally practice discharge to land
systems for three to eight months per year.
2. Ground cover utilized for municipal systems is divided
between grass and crops. Industries generally use
grass cover.
3. Land application systems are generally used on a daily
basis, seven days per week.
4. Application rates for crop irrigation are very low in
terms of inches of water per week. Two inches or less
was commonly used (Two inches per week equals
48,000 gallons per acre per week.)
5. Many types of soils were used, although sand, loam and
silt were the most common classifications given. Two
systems using application over many feet of sand were
applied up to 8 inches per week, and one system on
clay was applying only 0.1 inch per day.
6. Most operating agencies, municipal and industrial,
are planning to either expand or continue their land
application installations. The few examples of
systems which had been abandoned were due to either
the desire to make a higher use of the land, or
because of reported overloading and poor operation
of the land application facilities.
7. Industries surveyed generally treat their total
waste flow by land application.• Practices of muni-
cipalities varied from less than 25 percent to
all wastewaters produced.
8. Secondary treatment is generally provided by
municipalities prior to land application, often times
254
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accompanied by lagooning. Industrial systems often
treated their process wastes by screening only.
9. Spray irrigation is the most frequently used (57
facilities) method of application, although most
municipalities use more than one method. Ridge and
furrow irrigation is used at 23 facilities and
flooding irrigation is used by 34 systems. Industry
generally used spray irrigation.
10. Land use zoning for land application sites is
predominantly classified as farming, with some
residential zoning in contiguous areas.
11. Wastewater generally is transported to the application
site by pressure lines, although a number of
municipalities are able to utilize ditches or gravity
flow pipe lines.
12. Many community land application facilities have been
in use for several years more than half for over
15 years. Industrial systems are relatively more
recent.
13. Renovated wastewater is seldom collected by
underdrains; rather, evaporation, plant transpiration,
and groundwater recharge take up the flow.
14. Land application facilities generally do not make
appreciable efforts to preclude public access.
Residences are frequently located adjacent to land
application sites. No special effort is made to
seclude land application areas from recreational
facilities and from those who use these leisure sites.
15. Monitoring of groundwater quality, soil uptake of
contaminants, crop uptake of wastewater components,
and surface water impacts is not carried out with
any consistency.
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The largest system which was surveyed serves Mexico City.
One of the more advanced systems which has not received as much
publicity as Perm State or Tallahassee is Colorado Springs, Colorado.
Engineering reports concerning both systems are included to give
an indication of the extent and use made of wastewater at these two
atypical facilities.
Mexico City has an elevation of approximately 7,500 feet in
a valley completely surrounded by high mountains. Population of the
City of Mexico is approximately eight million and an additional two
million people live immediately adjacent to the Federal District
boundaries.
In 1902 a canal and tunnel system was dug to convey wastes
approximately 70 kilometers (44 miles) north to the Tula area.
The City of Mexico is sinking 8 to 10 centimeters per year
and it is now necessary to pump into the canal system.
The City is served by a combined sewer system which has a
dry-weather flow of approximately 25 cubic meters per second (570 mgd)
Wet-weather flows reach 2,000 cubic meters per second (4,560 mgd).
The potable water system for the area is from a well field some
distance away. Approximately 35 cubic meters per second (800 mgd)
are supplied to the city.
Due to the increases in storm runoff and possibility of
flooding the central part of the city at any time because of pump
failures or excessive storm flow, a deep tunnel system is being
constructed at a cost of 4 billion pesos ($320,000,000). The annual
cost of disposal will be reduced by the pumping costs now required,
an amount equal to amotization of about one-half of the construction
cost. The tunnel is from 150 to 750 feet deep with 37 shafts. The
tunnel is to be completed in March 1974, at which time approximately
70 percent of the dry-weather flow of the canal will be diverted to
the tunnel. The tunnel is being designed for a storm flow of
200 cubic meters per second.
The tunnel is 6-1/2 meters (26 ft) in diameter and has a
design velocity of one meter per second for dry-weather flow and
six meters per second for storm flows. The Mexico City area has
700 millimeters (27 inches) of rainfall per year.
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In addition to the untreated flow, 4 cubic meters per second
are treated in five secondary treatment plants within the city,
which have a capacity of 7.5 cubic meters per second. This flow
is used for irrigation of parks, playgrounds and other large public
areas, as well as for the filling of lakes in parks and for fountains.
Solids from the treatment plants are discharged to the untreated flow.
The flow used within the city is chlorinated prior to application and
is used in Chapultepec park, the University of Mexico and Olympic
sports arena and parks.
The treatment plants are operated only during the dry season
November through May. The Federal District has determined its costs
for treating the effluent for watering within the city at
25 centavos per cubic meter ( 8 cents per 1,000 gallons) as contrasted
to the cost of treating and distributing drinking water at 50 centavos
per cubic meter (16 cents per 1,000 gallons).
The balance of the sewage, approximately 30 cubic meters per
second, is discharged to the irrigation canal. It is estimated
that approximately 95 percent of this flow reaches the land; the
balance is lost to evaporation and infiltration.
The irrigation area was formed as a cooperative; the government
owns the land but has given it to farmers as long as the land is
used for fanning. In the Tula Hidalgo approximately 47,000 hectares
(111,746 acres) are being irrigated at this time and plans exist
for a phase two of 27,000 hectares irrigated, and for phase three,
an additional 13,000 hectares will be irrigated. In the Tula
Hidalgo 24,837 hectares are farmed by 20,295 Ejidos (heads of families).
The balance of the 20,369 hectares are owned by 8,278 persons.
The area is served by the Tepeji River and flow not used for
irrigation eventually flows to Tampico. There are three storage
reservoirs for irrigation waters, totaling 201 million cubic meters.
During the dry season sewage and irrigation water are jointly used
and during the wet weather natural river water is stored for use during
the dry season. On an annual basis, approximately 700 million cubic
meters (185,000 mg) of sewage are used and 200 million cubic meters
(54,000 mg) irrigation water are used. In 1971, 672,654,000 cubic
meters were used on the 4.7,000 hectares.
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Upon the 47,000 hectares, 1,476,749 tons of food products
were raised, with a value of 333,783,710 pesos ($26,701,000).
Crops are grown by farmers in response to market demand. They have
not found sewage to be toxic to any natural crops. Only one crop
per year is produced, with the exception of alfalfa where ten cuttings
are made. Crops include alfalfa, corn, wheat, tomatoes, chiles,
flowers and other truck garden crops. Table 1, Summary of Agriculture
Production 1971-1972, presents the tons of crops raised in the
Tula Hidalgo.
The Tula Hidalgo is operated by the Federal Department of
Agriculture and the costs of the operations are paid by the Ejidos
on the following basis: 30 pesos ($2.40) per hectare for 40 percent
of the land farthest from the head of the district and 20 pesos
($1.60) per hectare for the remaining 60 percent by individual
holdings per time of irrigation. Each irrigation is 20 centimeters
(7.8 inches) of water on the land.
The farmers have found that the alfalfa commands a premium and
also is heavier than normal due to the use of sewage.
Drinking water for the 100,000 residents of the area is
from springs above the Hidalgo. Land adjacent to the project is
worth 500 pesos per hectare ($17/acre). The irrigated land is worth
30,000 to 50,000 pesos ($100 - $160 per acre) per hectare. The
irrigation area receives 400 cm (16 inches) per year of rainfall.
The Hidalgo has excellent records indicating the amount of return
flow to the river because of gauges on the river above and below
the district.
Observations were not available as to the changes in the
quality of the flow at the point of distribution, as compared to
inland. It is apparent that the canal acts as one long oxidation
ditch and that slime growths and such along the canal must be
oxidizing part of the material. ABS is a problem, inasmuch as
Mexico has not switched to soft detergents. Foaming was noticed at
the canal and gate structures. Odors along the canal are not
noticeable. The area which is fanned has few homes adjacent to
the farm land. Most people live in the villages where conveniences
are available. All work is done by hand. No farm equipment was seen.
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TABLE 1
SUMMARY OF AGRICULTURE 1'RODUCTION - PRODUCTION YKAR 1971-1972
03 IRRIGATION DISTRICT - TULA HIDALGO
CROP
AlTAlTA VERDE
A JO
AIUTJOM
AVI.KA VERDE
CAI.AIIACITA
CEIIADA GUANO
CEBADA PAGO
CEBOLI.A
CILANTRO(SEMILLA)
COL
CII1CHARO
CHILLS VERDE
FLORES
FR1JOL GRAND
FRIJOL EJOTE
ESPINACA
FKUTALES
GIRASOL
HABA
01TOMATE
LECHUGA
MA1Z GRAND
MA17 RASTROJO
MAIZ VERDE
•NABO FORRAJE
MELON
PEPJNO
PRADERA
TOMATE
7RIGO GRAND
SANDIA
CROP
ALFA'LCA
GARLIC
PEAS (iARGE)
GREEN OATS
SQUASH (SMALL)
BARLEY GRAIN
BARLEY (FORAGE)
ONION
PARSLEY SEED
CABBAGE
PEAS
GREEN HOT PEPPERS
FLOWERS
NAVY BEANS
AM.STRING BEANS
SPINACH
FRUIT TREES
SUNFLOWER
LIMA BEANS
AM. TOMATO
LETTUCE
CORN (KERN F.LS)
CORN(FORAGE)
CORN(SWEET)
FORAGE TURNIPS
MELON
CUCUMBER
MEADOW GRASS
TOMATOE
WHEAT GRAIN
WATERMELON
HFCTARrS
"I23~9~6'.40
91.1)0
12.89
2990.75
671.33
1865.43
23.79
3.53
27.95
1.00
768.80
10.41
1259.02
58.30
25^08
37.19
95.84
1554.65
74.47
17053.60
101.20
112.37
•1.00
34.74
12.80
216.90
7,293.79
JMO
46,809.95
ACRES
115,620.65
NOTE: 1 metric ton
1 (U.S.) ton
1 hectare
V.I (U.S.) tons
0.907 metric tons
2.47
20
54,426
7,282
3,645
7T,
,/&•',
410
4,059.87-',
168.909
•4.583
DOT. 84 3
7.900
8,231.350
1,563.870
151.5M
9.020
21 3. ICO
230. 57c',
1,990.070
49,437.870
l/i57.7G-1
70,260.525
65,179.023
7,084.000
1,011.330
7.100
166.752
2,080.000
2, 051 ,,706
13,865.494
_ 3.900
1, 176,749737 I
U.S. TONS
1,624,424.30'
NOTE: The crop hectares listed arc more than the hectares of land
available since a second crop in some instances has been produced
on the same land.
Source; City of Mexico, D. F.
259
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The City of Colorado Springs, after severe droughts in 1953,
initiated a limited program to water municipally owned grassed areas
with wastewater treatment plant effluent. Severe watering restric-
tions placed on all residents had previously resulted in the loss of
*
large grassed areas.
The present system is divided into two lines. The western
line is composed of a pressure line to an abandoned water reservoir
from which the effluent is again pumped to the facilities to be
irrigated. These include a median strip where an old gravity irriga-
tion system was previously used for flood irrigation of the wide
median strip, Colorado College, and a new, exclusive country club
area, "Kissing Camels." The latter area has its groundkeeper
personnel water the golf course and the lawns of numerous high-class
residences on the grounds.
On the pressure lines, a series of fire hydrants have been
located, painted a distinctive blue and white color. These fire
hydrants may be used by contractors who can utilize the low-quality
water for purposes such as construction and tree watering. An
annual fee is paid. In addition, the Fire Department may use the
lines in an emergency.
The eastern line is pumped to an abandoned water reservoir
from which, by gravity, several facilities, including a cemetery,
park, a private development (Printers Union Home and Office) , and
a golf course are watered.
The system has been designed to provide water for irrigation
along the Interstate Highway System. Although the State Highway
Department participated in the cost of one of the pressure lines, it
has not used the system.
Private customers are charged a rate of 10 cents per thousand
gallons plus pumping, which averages approximately 14 cents per
1,000 gallons. The 1969 sales were $24,090; 1970 sales $36,815;
1971 sales $36,598. In 1971, tertiary treatment was added. Flows
for irrigation are subjected to either physical-chemical treatment
or sand filtration. The cost for new sales of water will be 30 cents
per thousand gallons plus pumping.
260
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The operating cost by the City for the irrigation operation
was: 1969-$42,Q65; 1970-$34,197; and 1971 with tertiary treatment
flow - $137,689.
The reservoir on the west section is open to the public and
public fishing is allowed. On public properties, in accordance with
Colorado State regulations, some signs exist pointing out that a
nonpotable water source is used for watering. On public property,
either underground sprinkler systems or portable aluminum pipe
systems are used.
Some odor complaints have been received by the City when
the reservoirs have been allowed to hold water for several days
because of rain. The entire system is operated on the basis of
demand for watering and the water is taken only as desired by the
users.
During 1971, 336 million gallons were treated by the
tertiary plant. Two hundred thirty were used for irrigation and
133 for industrial use.
The area of facilities watered on the east line includes
the Waste Water Reclamation Plant, 27 acres; Evergreen Cemetery,
206 acres; Memorial Park, 115 acres; ITU, 50.5 acres; Lunar Park,
3.4 acres; Otis Park, 2.4 acres; and Patty Jewitt Golf Course,
235 acres. On the west line: Colorado College, 55 acres; parkways,
2.3 acres; Acacia Park, 3.7 acres; and Kissing Camel Golf Course,
82 acres.
The cost of the improvements to the western line was
$62,000; to the eastern line $196,890; and for the tertiary
treatment, $1,054,000.
In summary, the land application of treated wastewater presents
an important treatment alternative which must be considered in
evaluating construction of new or upgraded facilities.
261
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
Tel: 202-426-8976
Bel ford L. Seabrook
APPENDIX
FACT SHEET - IRRIGATION OF LIQUID DIGESTED SLUDGE - MOVIE, WEALTH FROM
WASTE - HERTFORDSHIRE, ENGLAND,
by Bel ford L. Seabrook, Sanitary Engineer
This 1s a film, made for public relations purposes, aimed at the
public in England within the distribution area of the sludge that 1s
produced by one English sewage authority. The hydraulic volume
references in the film are 1n British Imperial gallons. All volume
references 1n this fact sheet are 1n U.S. gallons.
The West Hertfordshire Main Drainage Authority, located at
Rlckmansworth, about 20 miles north of London, England, serves an
area of 210 square miles with a population of 550,000. 141,000 cubic
meters (37 mgd) of waste water each day, 80$ of which is from domestic
sources, is treated in a two-stage treatment facility. The Authority
was organized in 1939, but the irrigation of digested sludge was not
commenced until 1952. To avoid public reference to sewage, sewage
connected terms, and the connotation associated with the use of such
terms, the digested sludge has been given the name of HYDIG. The
effluent from the secondary treatment plant, having a quality better than
10/10 (Royal Commission standards: 20 ppm SS & 30 ppm BOD), is discharged
Into a river. The effluent at discharge Into the river contains on the
average 18 ppm of oxidized nitrogen (.03 ppm ammonia) and 5 ppm of phosphorus,
This satisfactorily disposes of 97% of the problem. The rest of this
story concerns the remaining 3%, most of which 1s digested sludge.
The primary objective 1s to apply the digested sludge to the land,
that is to dispose of it in a manner that is not objectionable to the
community. A secondary objective 1s to reduce to a minimum the amount
of waste water that must be irrigated along with the sludge. This is
an economy measure intended to substantially reduce the volume of materials
being handled. Since 97% of the secondary effluent has been improved
in the biological treatment plant to such an extent that 1t is better
than the receiving stream, 1t 1s discharged Into a river. The remaining
effluent, which contains about 3% solids in the form of digested sludge,
is used for irrigating crop land. The Authority officials believe that
if a feasible means, at a reasonable cost, can be found to increase
the solids content up to 5% or 6%, it could be applied to the land
with the same equipment.
ft-/
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APPENDIX
The primary and activated sludges are fermented in digestion tanks
for 20-24 days at temperatures of 90-98°F. The production of digested
sludge is a continuous method; some sludge is irrigated every day except
Sundays, the amount being approximately 1/24 of the contents of the
digestion tanks, or from 250,000 gallons to 500,000 gallons. The
capacity of the secondary sludge storage tanks is approximately 8 1/2
million gallons, which permits winter storage up to 6 weeks.
The daily flow of 37 million gallons of waste water produces about
90 million gallons per year of liquid digested sludge. The sludge has
a solids content of 3%, more or less, which is applied to the
land, either by spreading from tank trucks as they roll across the
fields, or by irrigation from pits or large stationary storage tanks
located adjacent to the fields. Approximately 1000 acres are owned by
the Authority and used as experimental farmland, and the balance of
the 6000 acres is operated or owned by some 62 private farm units.
The cost of transporting and applying the HYDIG is about $6 per 1000
gallons which contrasts with the cost of ocean dumping of about $9 per
1000 gallons. The disadvantages of tank truck operation are more than
offset by the savings that result from having neither investment in
5000 acres of privately owned farmland nor farm operating expenses on
this land.
The irrigation is done on gravel soils that are fairly firm and
easily drained. The crops grown include grass, forage crops, English
black beans, grains, potatoes and other root crops. There have been
no build-up of toxic salts, no cattle disease, no objectionable odors,
no fly problem, and no community objections. The public health officers
are satisfied that the Herts irrigation procedure is not a threat to
public health. There have been some individual complaints, but the
majority of these have involved the use of the highways by the large
tank trucks. The principal problem appears to be the potential long-
term harmful effects of certain undesirable trace metals 1n the sludge.
The toxic metals most frequently found are zinc, copper and nickel.
Research work by the British Ministry of Agriculture has established
that nickel is 4 times more toxic to plant life than copper which is
itself, twice as toxic as zinc. This discovery made it possible to
simplify the composite effect of the metals in any particular sample
of sewage by expressing the effect as "ZINC EQUIVALENT."
The Authority has set for itself these tentative guidelines pending
further research work. In a sample of virgin soil which is free from
metal traces, if no more than 250 ppm of zinc-equivalent is allowed
to build up in the top soil, then there is no risk of damage to plant life
due to the metals. Unfortunately, the build-up appears to be cumulative.
The Authority has tentatively selected a 30-year period for the
application of sludge to a particular piece of land, and is currently
limiting the annual dressing to no more than 1/30 of the 250 ppm arbitrary
maximum. Research is also being done to determine whether or not
over a prolonged period the minute traces of lead, cadmium, arsenic and
mercury.'will nave any deleterious effect upon plant life. Chromium
as a chromium salt in sewage
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APPENDIX
was found to be non-toxic, except 1n high concentrations. Boron unlike
the other metal traces quickly leaches down Into the sub-soil. The
other principal and tentative injunction which the British Ministry of
Agriculture rendered related to the avoidance of an acidic soil condition,
It has been found that when the soil becomes more acid than pH 6.5 it
seems to accelerate the toxic effects of certain trace metals on the
plant life. As a general precaution livestock should not be allowed
to graze fields to which sewage has recently been applied until after
rain has washed the edible plant sections clean. Rain will reduce the
potential hazard to livestock from ingestion of lead and mercury which
may have been deposited on the plant surfaces. The Hertfordshire
Authority points out however that there is no evidence to show that
there has ever been a problem from Ingestion of such metal traces when
livestock have grazed fields that have not been washed clean by rain.
In fact, palatability tests have led to observations that the cattle feed
avidly upon grass which has received a fresh application of liquid
digested sludge. However the Authority officials say-that clearly 1t
is common sense to let the sludge be washed off the grass before grazing.
With due care for these precautions, this technique could become a
viable alternative in response to Section 304(d)(2) of the new amendment.
Public Law 92-500, enacted October 18, 1972, of the Federal Water
Pollution Control Act of 1956, which calls for EPA publication of
Information on alternative waste treatment systems and techniques. As
stated in PL-92-500 sections 301(b)(l)(A) (best practible control
technology by 1977) and (b)(2)(A) (best available technology by 1983),
this is needed to accomplish the national goal of eliminating the
discharge of all pollutants. It Is definitely an Improvement over the
Australian and German applications of raw sewage directly to the land.
It would appear to be an improvement over the Muskegon, Michigan design,
when that project becomes operational in 1973 or 1974.
With the emphasis under the 1972 Amendments to the Act on finding
alternative techniques to the conventional methods of treating waste
water, there are no sludge irrigation operations in the United States
with anywhere near the 20 years experience of the Hertfordshire system.
Perhaps the nearest 1n terms of experience 1s the experiment at Penn
State University. This experiment was started in 1961, using about 5-6%
of the secondary effluent (500,000 gallons per day) from the local
municipality's treatment plant. The primary objective of the Penn
State experiment is to renovate the secondary effluent, that is, to
make it suitable for reuse for other purposes (but not necessarily
potable water). During the last two years at Penn State, however,
liquid digested sludge equivalent in volume to that produced by the
effluent being irrigated has been injected into the irrigation pipelines
so that the sludge can be irrigated along with the secondary effluent.
The solids content of the mixture of effluent and sludge is of course a
great deal lower than the 3% figure at Herts. The Penn State managers
have said that they have experienced no difficulties with this procedure,
although they have not yet reported any conclusions from it.
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APPENDIX
It seems to me, 1n contrast to the problems created by the dumping
of sanitary wastes Into rivers, lakes and oceans Including the metals
1n such wastewater, that currently the metals problem Involved in
sewage Irrigation on land 1s by far the lesser problem. The technique
of treating the secondary plant effluent so that 97% of 1t can be
discharged directly Into surface waters and so that the balance can
be Irrigated in the form-of liquid digested sludge has now been
adopted by approximately 40% of all municipal treatment works in
England. From the standpoint of the hydraulic volumes to be handled,
this technique has substantial advantages. 97% of the dally flow
is treated and renovated sufficiently to permit 1t to be returned
to surface streams with a quality higher than the receiving waters.
Only the remaining 3% in the form of liquid sludge needs to be
irrigated. Since the 3% consists of effluent plus digested sludge,
free of objectionable odors, and brings no associated fly problem
with 1t, it comes closer than any other sludge Irrigation technique
to meeting the aesthetic requirements of the community 1n which 1t
would be used. While it may not yet be feasible for a large megalopolis,
certainly the Hertfordshire experience over the last two decades has
demonstrated that 1t is acceptable and practical for certain communities
of 500,000 population.
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THE FOLLOWING PAGES ARE DUPLICATES OF
ILLUSTRATIONS APPEARING ELSEWHERE IN THIS
REPORT. THEY HAVE BEEN REPRODUCED HERE BY
A DIFFERENT METHOD TO PROVIDE BETTER DETAIL
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This page is reproduced at the
back of the report by a diflcrent
reproduction method to provide
better detail.
Figure ,. lrrig.tion SYStem usea ,n Pulton Count, to
Fertilizer to strip-mined Land.
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This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
r.gure 2. The Incorporation System Applying Liquid Fertilizer to Stnp-Mined Land u, Fulton
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Figure 1.
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
115
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