DESIGN SEMINAR
FOR
LAND TREATMENT OF MUNICIPAL
WASTEWATER EFFLUENTS
Prepared For
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
TECHNOLOGY TRANSFER PROGRAM
AN OVERVIEW OF
FOUR SELECTED FACILITIES
APPLYING
MUNICIPAL WASTEWATER
ONTO THE LAND
-------
IV
IbO
,VS7
jlj-f/f AN OVERVIEW OF FOUR SELECTED FACILITIES THAT APPLY
MUNICIPAL WASTEWATER TO THE LAND
By
Frank M. D'ltri, Thomas P. Smith, Herman Bouwer, Earl A. Myers, and
Allen R. Overman
INTRODUCTION
Municipal wastewaters are renovated primarily to control the nutrients
responsible for the accelerated eutrophication of receiving waters, and
in some cases to reuse the wastewater itself. Since the Water Quality
Amendments of 1972 requires that all discharges of pollutants into the
nation's waterways be halted by 1985, major technological advances will
be required to meet these objectives. This means that new methods of
wastewater treatment will have to be devised, and responsible development
will hinge on learning much in a short time from the projects now underway.
Where sufficient land is available and the hydrological conditions
are favorable, the wastewater can be renovated through infiltration basins,
ridge and furrow, overland flow, or sprinkler systems that recharge
groundwater and offer viable alternatives to chemical or biological
tertiary treatment systems. As the wastewater moves through the soil in
a properly managed system it removes or greatly reduces suspended solids ,
biochemical oxygen demand, microorganisms, phosphorus, fluorides, heavy
metals, nitrogens, and many other substances. Thus, a number of experi-
mental or operational systems have been designed to renovate wastewater
by percolation through the soil.1 Four facilities that are applying
municipal wastewater to the land are discussed in this paper. All of the
projects have somewhat different background histories in terms of what
their purpose is, what the natural conditions are, and the problems of
implementation. Besides this history, the design criteria of the facility
and its operation are described as well as the soil characteristics and
monitoring schedules to assess the chemical and biological parameters.
1. The Michigan State University Water Quality Management Project
was designed for research and demonstration of wastewater renovation and
reuse techniques through a combined aquatic and terrestrial system.
2. The City of Tallahassee, Florida, Spray Irrigation system applies
wastewater to sandy soils with high infiltration rates throughout the year.
3. The Flushing Meadows Project west of Phoenix, Arizona, is re-
claiming municipal wastewater by groundwater recharge through shallow
infiltration basins.
Authors: FRANK M. D'lTRI, Ph.D., is an Associate Professor of Water
Chemistry, Institute of Water Research and Department of Fisheries and
Wildlife, Michigan State University, East Lansing, Michigan U882U.
THOMAS P. SMITH, P.E., is the Director of Underground Utilities,city of
Tallahassee, Florida 32301+. HERMAN BOUWER, Ph.D., is the Director of
the U. S. Water Conservation Laboratory, Agricultural Research Service,
U. S. Department of Agriculture, Phoenix, Arizona 850I+O. EARL A. MYERS, Ph.D., P.E.
Proiessor Emeritus of Agricultural Engineering, Pennsylvania State
University, University Park, Pennsylvania 16802, presently Engineer in Charge,
Williams and Works, Route No. 1, Box 212, Thomasville, Pennsylvania 17361*.
ALLEN R. OVERMAN, Ph.D., is a Professor of Agricultural Engineering, Univer-
sity of Florida, Gainesville, Florida 32601.
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2
U. The Pennsylvania State University Wastewater Renovation and
Conservation Project began as a pilot study in 1962 to evaluate the
effectiveness of land disposal as one alternative to releasing the
secondary effluent from municipal wastewater into streams, rivers, or
lakes.
Several factors differentiate the four facilities. The most signifi-
cant is that three of them were designed initially as pilot plants to
provide alternative methods of wastewater removal from currently operating
sewage treatment facilities. The exception is the Water Quality Manage-
ment Project at Michigan State University which was designed exclusively
as a research and development project to study alternative aquatic and
terrestrial applications of wastewater to utilize the components as food
for plants and animals. Because the facility was created with research
in mind and did not occupy or fit into an existing sewage treatment
plan except in that the effluent is pumped from the East Lansing Sewage
Treatment plant after being given secondary treatment, the land could be
studied in its natural state before the project was implemented and can
then be charted as time goes on to determine if any changes occur in
the groundwater, soil or other variables at the site. For this purpose,
also because the site is experimental, the quantity of waste can be care-
fully monitored and controlled.
Both Michigan State and Penn State have seasonable variables that
affect their operations whereas a year round operation is possible at
Tallahassee and Flushing Meadows. The latter is the only one of the
three that has no spray irrigation system. Instead the water is pumped
into infiltration basins from which it is absorbed rapidly into the soil.
All three of the pilot plant programs were begun to determine if land
disposal could provide an alternative for or addition to the conventional
sewage treatment systems, and all are now being expanded to meet the demand
by the increasing population. At Tallahassee the decision was made to
apply all of the city's wastewater onto the land by sprinkler irrigation
as soon as possible. At Penn State the expansion plan drawn up in 1968
provided for land application of all of the wastewater, but budget
constraints limited construction to only three quarters of the system.
It will be operational in the spring of 1976. At Phoenix the city has
recently constructed four 10-acre rapid infiltration basins to renovate
approximately 15 MGD of secondary effluent for unrestricted use by an
irrigation district. The design of this project was based on data from
the Flushing Meadows Project to plan the hydraulic loadings and antici-
pated quality of the renovated water. If this project is also successful,
a third and larger rapid infiltration basin system will be constructed.
THE MICHIGAN STATE UNIVERSITY WATER QUALITY MANAGEMENT PROJECT
HISTORY OF THE WATER QUALITY MANAGEMENT PROJECT
After the initial concept was developed, financial support and
approval to implement the design were received from the Michigan State
University Board of Trustees in December, 1966. In 1968 the 500 acre
project site was designated on the south end of the campus. Shortly
thereafter, The Rockefeller, Ford, and Kresge Foundations pledged 1.2
million dollars in support of the project. During the summer of 1972
funding approval was also received from the Environmental Protection
-------
3
Agency and the State of Michigan through the Clean Water Bond Act.
Construction began in April, 1973. In September, 1973, the lakes were
filled with wastewater and a number of types of aquatic plants were
sown. The Water Quality Management Project facility was completed in
the spring of 197U and officially dedicated that October.
THE WQMP FACILITY AND ITS OPERATION
This $2.3 million outdoor laboratory on the Michigan State University
campus consists of four artificial lakes with a total surface- area of Uo
acres and an average depth of 8 feet. The site also includes three one-
acre marshes and 320 acres of land of which 150 acres are equipped for
spray irrigation (See Figure l). Municipal wastewater undergoes primary
and secondary treatment at the East Lansing Sewage Treatment Plant before
being delivered to the lakes in k.5 miles of 21 inch asbestos-concrete
pipe. Up to two million gallons can be transported per day. The waste-
water undergoes chemical, biological and physical renovation over 30 to
60 days while it passes sequentially through the four lakes. The water
then can be released into surface streams or sprayed onto the land.
The prime challenge of wastewater treatment is to concentrate and
remove pollutants from very dilute solutions. The Water Quality Manage-
ment Project offers the opportunity to evaluate the potential of a number
of individual and combined natural aquatic and terrestrial ecosystems for
removing wastes in a productive manner. The great flexibility of this
project allows researchers to test various methods of using fields,
forests, marshes and lakes to produce more.food and fiber from wastewater
in a manner that will protect public health. Moreover, the risk is
diminished of causing new problems because more chemicals are added for
treatment because most of the treatment is biological. By themselves
plants and sediments remove substantial quantities of the waste constituents
f£om the solutions.
For example, one aspect of the project takes advantage of the fact
that solar energy generates photosynthesis. As algae and rooted aquatic
plants grow in the lakes, they take up the abundant nutrients in the
wastewater and alter its chemical composition to accelerate the physical
and chemical removal of the remaining pollutants. They settle to the
bottom of the lakes and then are pumped through the irrigation system to
the terrestrial site where the concentrated wastes also accelerate the
growth of plants. Both aquatic and terrestrial plants are to be harvested
for animal food or soil conditioners.
CHEMICAL AND PHYSICAL MONITORING PROGRAM
The Water Quality Management Project Laboratory is monitoring over
50 chemical, physical and biological parameters as the effluent passes
through various stages from the treatment plant through the lake and
irrigation site. These parameters and the sampling timetable are pre-
sented in Table I. The average concentrations and ranges of selected
chemical parameters for the system is presented in Table II. This
analytical program will provide a data base for all scientists conducting
research on the project.
Daily 2h hour composite samples are collected to represent raw,
primary, and secondary effluent at the East Lansing Sewage Treatment
-------
SECONDARY EFFLUENT FROM EAST LANSING
SEWAGE TREATMENT* PLANT 2 M.G.D
LAKE SYSTEM
186 ACRES INCLUDING
40 ACRES OF LAKES
*2
REGIONAL MAP
CO » o
ER ZONE 3X
TO IRRIGATION
PUMP—^STATION
IRRIGATION SYSTEM
314 ACRES
PASTURE
CROPS
BUFFER 2?
WATER QUALITY
IANAGEMENT FACILITY
FORAGE
CROPS
RESEARCH
W
INSTITUTE OF WATER RESEARCH
MICHIGAN STATE UNIVERSITY
° SAMPLING WELL
w;
BUFFER ZONE
PREPARED BY
DIV OF CAMPUS PARK & PLANNING
M S.U MAR 21. 1973
FIGURE 1.
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TABLE I
The Michigan State University Water Quality Management Project chemical, biological, and physical
monitoring program experimental analyses design.
Sampling Frequency
Chemical, Biological
or Physical
Parameter
STP
Lake
Water
Lake
Sediments
Campus
& Test
Wells
Felton
and
Herron
Creek
Soil
Samples
Analyses
Per
Year
1.
Temperature
cont
cont
i+Y
MIS
MIS
2Y
1032
2.
PH
cont
cont
UY
MIS
MIS
2Y
1032
3.
Dissolved Oxygen
cont
cont
NSR
MIS
MIS
NSR
828
k.
Specific Conductance
cont
cont
kY
MIS
MIS
NSR
92k
5-
Turbidity
cont
cont
NSR
MIS
MIS
NSR
828
6.
Light Penetration
cont
cont
NSR
NSR
NSR
NSR
-0-
7-
Redox Potential
cont
cont
kY
MIS
MIS
2Y
1032
8.
Ammonia
D2UC
2D12C
kY
MG
M168C
2Y
5777
9-
Nitrate
D2UC
2D12C
kY
MG
M168C
2Y
5777
10.
Nitrite
D2UC
2D12C
¦kY
MG
M168C
2Y
5777
11.
Kjeldahl Nitrogen
D2**C
2D12C
kY
MG
M168C
2Y
5777
12.
Ortho phosphate
D2*tC
2D12C
kY
MG
mi68c
NSR
5669
13.
Total Inorganic Phosphorus
D2HC
2D12C
kY
MG
Mi68c
NSR
5669
Ik.
Total Phosphorus
D21+C
2D12C
kY
MG
mi68c
2Y
5777
15-
Chloride
D2hC
2D12C
kY
MG
mi68c
2Y
5777
16.
COD
D2hC
2D12C
kY
MG
mi68c
2Y
5777
17.
Silicates
W168C
W168C
NSR
MG
mi68c
NSR
12UU
18.
Hardness
D2ltC
2D12C
NSR
MG
mi68c
NSR
5573
19-
Cyanide
W168C
W168C
NSR
MG
Ml68c
NSR
12U1+
20.
Sulfide
W168C
wi68c
kY
MG
mi68c
NSR
13^0
21.
Alkalinity
D2hC
D2'4C
NSR
MG
Mi68c
NSR
27^8
22.
Phenol
W168C
Wi68c
NSR
MG
mi68c
NSR
12UU
23.
Dichromate
Wi68c
Wi68c
NSR
MG
M168C
NSR
12UU
2k.
Fluoride
Wi68c
Wi68c
NSR
MG
Mi68c
2Y
1352
25.
Sulfate
Wl68c
wi68c
kY
MG
Ml 68c
2Y
lkk8
26.
Boron
D2hc
2D12C
kY
MG
Mi 68 c
2Y
5777
-------
Table I (cont'd)
27.
Total Carbon
D21+C
2D12C
1+Y
MG
M168C
2Y
5777
28.
Total Filterable Carbon
D21+C
2D12C
NSR
MG
M168C
NSR
5573
29.
Filterable Organic Carbon
D21+C
2D12C
NSR
MG
mi68c
NSR
5573
30.
Total Organic Carbon
D21+C
2D12C
1+Y
MG
mi68c
2Y
5777
31.
bod5
D21+C
2D12C
1+Y
MG
mi68c
NSR
5669
32.
Suspended Solids
D21+C
2D12C
NSR
MG
mi68c
NSR
5573
33.
Settleable Solids
D21+C
2D12C
NSR
MG
mi68c
NSR
5573
3U.
Dissolved Solids
D21+C
2D12C
NSR
MG
mi68c
NSR
5573
35.
Hexane Extractables
D21+C
2D12C
1+Y
MG
Mi68c
2Y
5777
36.
Aluminum
W168C
W168C
1+YDC
MG
M168C
2Y
11+00
37.
Arsenic
W168C
W168C
1+YDC
MG
M168C
2Y
11+00
38.
Cadmium
wi68c
W168C
1+YDC
MG
mi68c
2Y
lit 00
39.
Calcium
wi68c
W168C
1+YDC
MG
mi68c
2Y
1U00
1*0.
Chromium
wi68c
wi68c
1+YDC
MG
mi68c
2Y
11+00
1+1.
Cobalt
W168C
Wi68c
1+YDC
MG
mi68c
2Y
11+00
1+2.
Copper
W168C
W168C
1+YDC
MG
mi68c
2Y
11+00
1+3.
Iron
W168C
W168C
1+YDC
MG
M168C
2Y
11+00
1+1+.
Lead
W168C
Wi68c
1+YDC
MG
mi68c
2Y
11+00
1+5.
Magnesium
wi68c
Wi68c
1+YDC
MG
mi 68c
2Y
lit 00
1+6.
Manganese
Wi68c
Wi68c
1+YDC
MG
mi68c
2Y
]4 00
1+7.
Mercury
Wi68c
Wi68c
1+YDC
MG
mi68c
2Y
ll+oo
1+8.
Nickel
vi 68c
wi68c
1+YDC
MG
mi68c
2Y
ll+oo
1+9.
Potassium
wi68c
W168C
1+YDC
MG
mi 68c
2Y
ll+oo
50.
Sodium
Wi68c
Wi68c
1+YDC
MG
mi68c
2Y
ll+oo
51.
Residual Chlorine
D21+C
SAR
NSR
NSR
SAR
NSR
365
KEY
Type of Sampling
Frequency of Sampling
C = Composite
G = Grab
DC = Core Sample
SAR = Sample as required
NSR = No sample required
IS = In situ analysis
CONT = Continuous
H = Hourly
D = Daily
W = Weekly
M = Monthly
Y = Yearly
Intergers preceeding the frequency code letter designate the numbers of samples taken within that period.
Interger preceeding the letter C indicates the length of the sample is composited.
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TABLE II
Average concentrations ( ppm ) and ranges (within parenthesis) of selected chemical parameters in East Lansing Wastewater
and the WQMP lake system during the period of October, 1973 - March, 1975.
East Lansing Wastewater Lake System
Chemical Parameter
Raw
Primary
Secondary
Lake I
Lake 2
Lake 3
Lake 4
Total Phosphorus
7.0
5-0
2.6
1.91
1.34
1.37
0.54
mg/l-P
(3.6-9.5)
(2.6-10.5)
(0.5-9-1)
(0.86-3.23)
(0.57-2.62)
(0.55-3.35)
(0.22-1.27)
Soluble Phosphorus
3.0
1.1
1.1
1.49
1.24
1.06
0.34
mg/l-P
(2.7-5.7)
(2.1-3.8)
(0.3-7-9)
(0.55-2.66)
(0.57-2.62)
(0.51-2.32)
(0.12-0.80)
Ammonia Nitrogen
9-3
l6
9-7
4.87
4.91
3.77
3.36
mg/l-N
(4.1-32)
(8.6-25)
(5.2-22)
(0.36-9-7)
(0.26-10.6)
(0.27-8.1)
(0.10-8.3)
Nitrite Nitrogen
0.005
0.25
0.25
0.15
0.09
0.16
0.06
mg/l-N
(<0.005-0.03)
(<0.005-0.13)
(0.07-0.90)
(0.006-0.33)
(0.03-0.18)
(0.02-0.15)
(0.20-0.09)
Nitrate Nitrogen
0.54
0.2
1.07
1.64
1.64
1.02
0.77
mg/l-N
(0.16-3.1)
(0.09-2.33)
(0.16-7-0)
(0.06-12.3)
(0.06-10.9)
(0.10-1.72)
(0.10-1.25)
Kjeldahl Nitrogen
25-3
26.3
12.7
9-75
9.45
8.53
5-73
mg/l-N
(4.4-38)
(18.7-45)
(8.5-28)
(1.16-21)
(3-30-15)
(4.50-15)
(2.0-14)
Total Carbon
183
171
120
55
47
43
31
mg/l-C
(67-202)
(55-215)
(60-227)
(27-80)
(24-69)
(24-60)
(10-46)
Total Organic Carbon
73
50
30
14
8.6
9
7
mg/l-C
(43-105)
(38-97)
(12-111)
(6-48)
(0-11)
(4-13)
(3-20)
Boron
0.33
0.31
0.33
0.33
0.25
0.25
0.25
mg/l-B
(0.U9-0.19)
(0.35-0.29)
(0.42-0.21)
(0.41-0.26)
(0.30-0.20)
(0.31-0.23)
(0.29-0.19)
Calcium
108
110
113
U9
46
45
33
mg/l-Ca
(95-125)
(85-125)
(90-129)
(39-71)
(30-70)
(34-68)
(15-51)
Sodium
103
110
119
82
79.
78
59
mg/l-Na
(58-295)
(59-295)
(63-300)
(68-1.11)
(49-108)
(60-108)
(16-79)
Magnesium
25
26
24
20
19
19
12
mg/1-Mg
(20-29)
(20-30)
(20-23)
(14-32)
(13-32)
(14-32)
(4-20)
Manganese
0.16
0.09
0.05
0.05
<0.05
<0.05
mg/l-Mn
(0.10-0.39)
-
(0.03-0.18)
(<0.05-0.10)
(<0.05-0.09)
(<0.03-<0.05)
(<0.03-<0.05
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8
Plant. At the site of the Water Quality Management Project, 2b hour
composite samples are also collected from the influent to each lake and
the final effluent concentration from Lake b. The aquatic plants and
sediments are also sampled periodically. From these data the percentage
of elements for each parameter can be ascertained to facilitate tracing
their translocation into either the sediments or the aquatic plants.
Possible groundwater contamination at both the lakes and spray
irrigation sites is monitored by monthly analyses of well water. Forty-
one drift wells, lU shallow rock and b deep rock wells have been positioned
throughout the study area (Figure 2). All wells are b inches in diameter,
have a three foot copper screen point and sanitary seals to prevent
bacteriological contamination. The drift wells, the shallowest of the
three, are positioned in the glacial drift between UO and 60 feet deep.
Samples are obtained by pressurizing the drift wells and forcing the
water through a plastic pipe which extends to the bottom of the well.
Both shallow and deep rock wells extend into the aquifer which provides
the water supply for the University. The shallow rock wells are approxi-
mately 85 feet deep on the average, and the deep rock wells average about
180 feet. All are equipped with submersible pumps for sampling. The
most severe constraint in planning the sampling program from these wells
was to guard against contamination, particularly from potential sources
of viruses. Comparing post-operational data with background levels
should detect contamination from the lake or spray irrigation water.
A little surface runoff in the study area is channeled into Felton
Drain. Although it now flows only in the spring and summer, this will
probably increase significantly when spraj< irrigation begins. Therefore,
monthly samples will also be analyzed to determine the chemical character-
istics of this water. Effluent from Lake U can be discharged from an
experimental stream into the Red Cedar River via Herron Creek. At present
this creek, like Felton Drain, has an intermittant flow, but operational
flow levels will also be monitored. After the effluent has been sprayed
on the irrigation site, analyses will be conducted of water collected
in soil section infiltrometers and plant tissue. These data will indicate
how much of the remaining nutrients is absorbed by the soil and terres-
trial systems after the water has gone through the lake system.
A data management system is being implemented to handle the large
volume of data that is generated. This system is designed to: (l) store,
retrieve, prepare, manipulate and display all data, (2) transfer data
from the producer to all authorized users, and (3) prevent its loss,
destruction or unauthorized use. The data are stored on the Michigan
State University CDC 65OO computer under the mnemonics and code acquisi-
tion numbering of the STORET data management system whenever it can be
used.
MICROBIOLOGICAL AND VIRAL MONITORING
2
Microbiological and Viral Studies
At the East Lansing plant the wastewater treatment does not remove
all of the pathogens from the sewage, especially the viruses which are
difficult to destroy even by chlorinating the treated water. Forty
percent of the samples still contained viruses after the effluent was
chlorinated at the East Lansing plant. They remained in water that was
-------
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-------
10
discharged into the Red Cedar River just downstream from the Kalamazoo
Street bridge. Viruses also remained in forty-four percent of the samples
of river water taken as far as 500 feet downstream from the chlorinated
effluent. The samples ran as high as TO percent when the effluent was
not chlorinated.^
The WQMP microbiological and viral research program is designed to
find methods of preventing public health hazards when municipal waste-
water is eliminated and/or reused. The primary objectives of the program
are to:
1. Measure the pathogens, bacteria and viruses in the East Lansing
wastewater in the WQMP lakes and on the land after spray irrigation.
2. Determine the rate and efficiency of removing these pathogens
during processing by the East Lansing wastewater treatment plant and as
the water passes through the WQMP wastewater renovation system.
3- Monitor the water from the wells drilled around the Water Quality
Management lakes to detect contamination of the aquifer.
b. Monitor the purity of the University's water supply.
Analyses for viruses will be accomplished with methods that have been
used at the East Lansing wastewater plant for many years to isolate
pathogenic Salmonella and Shigella. Studies at the original^ and present
water treatment plant have authenticated the value of one method for
isolating viruses in wastewater." Pad samplers, H inch squares of
absorbent cotton, are placed between two layers of cheese cloth and are
held in place by sewing the three layers together. They will be used on
all flowing water to trap bacteria and virus particles. After the pad
accumulates and concentrates the bacteria and viruses, they can be
isolated with standard methods.7 Careful concentration and strict culture
procedures are required to isolate the complex viruses. The fluid in the
pad is expressed and approximately 100 ml is concentrated by ultracentri-
fugation. The resulting "sediment" is then suspended in approximately
3 ml of the supernatant fluid in about a 1:95 volume concentration.
After the bacteria are eliminated with antibiotics, the sample is centri-
fuged at slow speeds. If the bacterial sterility controls then are
negative, the sample is introduced on cultures of African green monkey
kidney cells. The isolated viruses are subsequently passed into secondary
cultures to be identified by serological methods if that is necessary.
Water samples from the monitoring wells are collected in gallon
volumes and passed through the continuous flow ultracentrifuge to remove
the viruses. Specific polyethylene imines are added to the water sample
to enhance survival of the infective virus particles. After concentration,
the samples are tested for sterility and introduced into the cell cultures
as described previously. If samples of water from the monitoring wells
contain viruses, the quantity will be determined by plaque counting.
These methods are routinely used in this laboratory for the isolation of
viruses from sewage and water.3'5
More enteric bacteria and viruses are in wastewater in the late summer
and early fall.** Therefore, more water samples are collected during these
periods. Pad samples will be taken at various stages of treatment in
the East Lansing wastewater plant as well as from the inflow and outflow
of the WQMP lakes to compare the recovery of pathogens. In both systems
more effort will be exerted to recover and analyze viruses than the
pathogenic bacteria which are more readily destroyed.
-------
11
While water samples from all the monitoring wells will be tested for
bacteria and viruses, those wells located close to the WQMP lakes will be
tested the most frequently. By recovering the coliform organisms,
bacterial slippage through the soil will be detected. If this occurs,
repeated tests will be initiated to determine the amount of slippage and
the radial spread of the viruses.
Aerosol samples will be collected for bacterial studies with such
sampling devices as the Anderson sampler®, silt sampler9, all glass
impingerlO, and syringe sample. Since no satisfactory method is now
available to sample enteric viruses in aerosols, it will be necessary to
develop methods at the spray irrigation site. Exposing live animals to
the aerosol is probably the only solution at this time. Studying the
animals' immunity response before and following exposure will give
evidence of infection from enteric viruses in the aerosol as exposing
the animals at various times and distances from the aerosol jets will
determine the relative hazards, if any.
SCOPE OF RESEARCH
The project site on the Michigan State University campus was designed
to encourage maximum cooperative research by scientists from such diverse
areas as limnology, botany, crop and soil sciences, economics, engineering,
entomology, fisheries, forestry, horticulture, hydrology, geology, socio-
logy, and zoology and chemistry.
The research can characterize the dynamics of wastewater constituents
in an integrated system of wastewater treatment and nutrient recycling.
First, the magnitude and direction of the biotic and abiotic factors are
being identified to determine how they affect the movement of phosphorus,
nitrogen and carbon in aquatic and terrestrial systems. The movement of
these nutrients, especially phosphorus, is being monitored through several
significant subunits of the WQMP.
The Aquatic System
In the aquatic system the nutrients and other pollutants are being
stripped from the water by various chemical, biological and physical
methods. First, some of them are adsorbed onto particulates which are
sedimented or directly sorpted onto bottom sediments. Second, some wastes
are removed by direct chemical precipitation whenever photosynthesis by
algae caused the pH of the system to increase. Third, some of these
materials are taken up by photoplankton and algae which die and transport
them to the sediments. A unique feature of the aquatic system is the
marsh area located between Lakes 2 and 3. This was included to investigate
how a marsh ecosystem removes nutrients, especially through denitrification.
Fourth, some nutrients have a secondary uptake into aquatic animals such as
zooplankton, insects, crayfish, tadpoles, minnows and fish. Fifth, aquatic
macrophytes also remove nutrients as they grow. This, in turn, provides
vast adsorptive surfaces which also remove these pollutants. To take
advantage of these removal mechanisms, the following ten species of aquatic
macrophytes were transplanted into the lake systems: Potamogeton foliosust
P.. peatinatus, P. orispus, Elodea Qanad.en8i.83 E. nuttallii, Mypiophyllwn
spioatwn, Najas flexiZis> Ranunoulus sp. and ValUanevia amerioana. Pre-
liminary studies of these macrophytes indicate that ash-free dry weight
-------
12
net yields of approximately 2.1 kg/m2 can be expected over a six month
growing season. The phosphorus and nitrogen content of the harvested
plants are typically about 1.5 and 5 percent, respectively.H
The Terrestrial System
Research on the terrestrial system involves delinating the short and
long term effects of wastewater effluent on soil hydrology, texture and
composition. In conjunction with these research programs, the survival
and growth of various types of trees, weeds and cultivated crops are also
being investigated.
12
Hydrologic Studies
Studies are also underway at the terrestrial site to explain the
hydrological response as the watershed receives spray irrigation with
treated municipal wastewater. Inasmuch as major producing wells are
situated nearby, the groundwater flow beneath the WQMP must also be
monitored carefully to assess the impact of the spray irrigation and
lake operations on the aquifer system. A comprehensive groundwater
study has been underway for over two years with the ultimate objective
of being able to predict and monitor the dispersive nature of water with
varying degrees of quality in the flow regions of the aquifer.
A digital computer program has also been developed and implemented
to make use of triangular finite elements.13 with the Galerkin method
the space variables can be distinguished in the basic unsteady flow
equation. Coupled with a central difference time step formulation, this
can solve the resulting systems of algebraic equations. The computer
model is designed to handle a variety of regional situations, including
steady or unsteady and confined or unconfined flows. Finite element
methods have definite advantages to model complex boundaries and variable
inputs such as recharge, pumping and field properties. Numerical solutions
for single well systems can be compared with known analytical results to
show some of the limitations of the model. Applications to field situations
emphasize flow analyses at the Water Quality Management site. A six year
simulation of the hydrodynamic response of the aquifer is also being
compiled with historical pumping data.
In another aspect of this project, flows are being analyzed in the
glacial drift overlying the aquifer. Once these flows have been traced
more accurately, the percolation of recharged water downward into the
main aquifer can be estimated and its response studied. In addition the
unsteadv flow model will be cnn-niori i.r-i+v, ¦ '
. iii auuiblC
unsteady flow model will be coupled with the convective-dispersion equa-
tions to predict water quality in the aquifer. In the future isoparametric
elements in the flow model will be used to ease data input manipulation
and reduce the reauired conmntpr -
n j _i_i j , —*¦* -Luuuu mam
and reduce the required computer storage. At the 1-
tne same time thp ova inhip
numerical techniques will be reviewed to solve the , a- avaiiabJe
.• j-c one convective-disDersion
equations and determine which ones are best suited for the present -vstem
Then comprehensive analyses of surface hydrology and runoff will be '
combined with subsurface flow at the spray irrigation site to explain the
total movements of irrigation water. ejiyxtun
now beingPmonitored 80^2!"^!!^low^ediction^0118 ^ ^
ri.ld data. Six automatic „t„
-------
13
test wells for continuous monitoring. At specified time intervals, water
levels in all of the test wells are manually recorded by means of drop
lines. Well borings have been analyzed and the coordinates of all the
test wells in the system have been determined.
Another hydrologic study is underway to assess the feasibility and
potential of a winter spray operation. The first overall objective is to
study the hydrologic balance of both natural and wastewater added to the
subwatershed for the winter months. Continuing investigations will monitor
the same parameters for an entire water year to determine water quality
for both surface runoff and infiltration.
The ten acre subwatershed is located in the southwest portion of the
spray region and drains into Felton Creek. Normal drainage is probably
through the subsurface with some runoff directly into the stream during
both periods. Approximately four inches of wastewater was applied to the
area per week on an intermittant schedule that started in January, 1975.
This research project should determine the impact of ice accumulation,
infiltration characteristics beneath the spray area, runoff response, and
the fate of nutrients in the runoff and infiltrated water. The integrated
data computed from these hydrologic studies will provide integrated data
on the water quantity and quality balance at the spray irrigation site.
Municipal Wastewater Effluent for Forage Crop Production to
Ik
Feed Livestock
The objectives of this research program are threefold. First, to
compare annual crops with perennial forage crops that produce the high
yields needed to feed livestock over several years without having to be
"e-established. When the crops are irrigated with high levels of sewage
affluent they can be harvested under varying time frequencies to obtain
the maximum biomass per acre. Second, to determine how soils and plants
fix minerals and the fate of heavy metals when wastewater effluent is
applied on perennial forage crops and annual crops. And, third, to
estimate the in vitro digestibility as an indicator of in vivo digesti-
bility to secure maximum biomass and adsorption of nutrients.
The field plots were established on two acres and irrigated from
?arly May to late November with 1, 2, and 3 inches of wastewater effluent
*ach week. Table III gives the estimated soil loading per acre with an
application of one inch of secondary effluent from the East Lansing plant,
¦he soil was categorized in October, 1973, as a uniform Miami loam by
-aking forty—five samples in 1 foot increments to a depth of 10 feet.
The eight perennial legumes and eight perennial grasses were estab-
lished in August, 1973, by seeding with a precision planter. In one area
'ye was sown in early September to serve as a winter cover crop. The
•nnual crops - two varities of hybrid corn, one forage sorghum, and one
orghum sudangrass — were established in mid-May with a no—till planter
¦fter the rye was treated with Paraquat herbicide to kill the top growth
Table IV).
Because of technical problems, the wastewater effluent was not avail-
ble until July l6, 1973. Then effluent spray levels of 1, 2 and 3 inches
er week were started and continued for Ik weeks until October 21 when the
inal plots were harvested and the soil was sampled. The untilled soil
bsorbed the effluent rapidly. One inch was absorbed in an hour without
-------
TABLE III
Estimated soil loadings per acre on application of one inch of East Lansing Sewage Treatment Plant
secondary effluent.
Concentration in
Secondary Effluent Grams per Pounds per Pounds per Acre
Chemical Parameter (mg/l) Acre inch Acre inch Per Year**
Organic Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Ammonia Nitrogen
Soluble Phosphorus
Total Phosphorus
Total Carbon
Total Organic Carbon
Dissolved Organic Carbon
Suspended Solids
Volatile Solids
Chlorides
Iron*
Manganese
Zinc
Nickel
Copper
Mercury
2.2
227
3.07
317
0.25
26
9-TO
126l
1.1
1U3
I4.9
637
150
15,^50
30
3,090
20
2,060
63
6,U89
25
2,575
26l
26,883
0.8l
83
0.09
9
0.19
20
0.11
11
0.0b
6
0.00005
0.005
0.5
36
0.7
50
0.06
U.l
2.77
200
0.3
23
l.U
101
3^
?,H5
6.8
1+89
h.5
326
Ik.3
1,027
5-7
^08
59.1
b,2^U
0.18
13.2
0.02
1.5
0. ou
3.1
0.025
1.8
0.013
1.0
0.00001
0.0008
* Iron is being added for chemical phosphorus removal at the East Lansing Sewage Treatment Plant.
** At a rate of two inches per week "between March and November (36 weeks).
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15
TABLE IV
Plants Irrigated with Municipal Wastewater Effluent For
Forage Crop Production
(Planted August, 1973, Harvested in 197*0
PERRENIALS
Grasses
Smooth bromegrass (Bromus inermis Leyss) cultivar Sac (southern)
Smooth bromegrass (Bronrus inermis Leyss) Canadian source (northern)
Orchardgrass (Daatylis glomerata L.) cultivar Nordstern
Tall fescue (Festuea arundinaoea Schred.) cultivar Ky. 31
Timothy (Phleum pratense Leyss) cultivar Verdant
Kentucky bluegrass (Poa pratensis Leyss) cultivar Park
Creeping foxtail (Alopecurus arundinacens Poir) cultivar Garrison
Reed canarygrass {Phalaris arundinaoea L.) Commercial
Legumes
Alfalfa (Mediaago sativa L.) cultivar Saranac
Alfalfa (Mediaago sativa L.) cultivar Agate (Phytophthom resistant)
Alfalfa (Mediaago sativa L.) cultivar Vernal
Alfalfa (Mediaago sativa L.) cultivar 520
Alfalfa (Mediaago sativa L.) cultivar Iroquois
Alfalfa (Medicago sativa L.) cultivar Ramsey
Birdsfoot trefoil (Lotus aornieulatus L.) cultivar Viking
Birdsfoo^ trefoil (Lotus aornieulatus L.) cultivar Carrol
Red clover (Trifolium pratense) cultivar Arlington
ANNUALS
(planted each spring starting 197*+, harvested the same year)
Corn (Zea mays L.) cultivar Funk G—
Corn (Zea mays L.) cultivar Mich. 560-3X
Sudangrass {Sorghum sudanense P. Stapf) cultivar Piper
Sorghum-sudangrass hybrid {Sorghum biaotor L. Moench x S. sudanense P. Stapf)
cultivar Pioneer 908
Forage sorghum {Sorghum biaolor L. Moench) cultivar Pioneer 931
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l6
any runoff even on plots that received three inches per week in three
applications of one inch each on Monday, Wednesday and Friday.
Yields of the first annual grass crop and three harvests of perennial
grasses were lower than expected, probably because in the 1^-week irriga-
tion period only approximately 27, 5^, and 91 pounds of nitrogen were
applied per acre at the 1, 2, and 3 inch levels of effluent, respectively.
At least 150 pounds of nitrogen per acre are necessary for a good yield of
perennial grasses and annual grass crops such as corn. Even at the high
rate of effluent spray with 91 lb of nitrogen per acre, annual and
perennial grasses were deficient by about 60 lbs per acre. However, the
legumes yielded well and showed no symptoms of mineral or nitrogen
deficiency. Apparently they fixed enough nitrogen symbiotically from
the air to obtain their optimum requirement of around 200 pounds per acre
since the effluent was deficient in applied nitrogen.
The soil was sampled in ^5 locations in one foot increments to a
depth of 10 feet for soil profile data on; pH, conductivity, extractable P,
K, Ca, Mg, Na, CI, N, Ca, Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn, plus
Kjeldahl N and total C. Samples of plants were analyzed for these elements
with: micro-Kjeldahl, emission spectrographic, atomic absorption, ion
electrode and colorimetric analyses. Certain elements such as: CI, Cd,
Co, Ni, and Pb are determined in plant tissues only if spot checks show
them to be a potential problem. Samples were collected in the fall of
1973 for baseline data and in 197^ after one year of cropping. The first
year's samples have been analyzed, and the 197^ samples are being analyzed
now. Plant samples have been ground up and are being analyzed for nitrogen
and minerals and for in vitvo digestibility.
In 1975 the same annual crops are again being planted. And soybeans
have been added because the other legumes performed so well in 197^- The
first effluent was applied in mid-April to be continued for 26 weeks.
Approximately TO, lUO, and 210 pounds of nitrogen are being added per acre
at 1, 2, and 3 inch levels in 1975. This should generate differential
yields of the annual and perennial grass crops.
In addition to research into design and management criteria for the
successful operation of this type of wastewater treatment, the WQMP has
inspired a multitude of innovative ancillary research projects. Those
factors which interact to control aquatic fertility will be evaluated as
well as hydroponics and high-rate fish culture. The terrestrial research
will enhance food and fiber production through the use of wastewater while
basic land resources are protected and improved. Other research areas
include the economic and social evaluation of this form of waste recycling
adjacent to a large urban population. For this the maximum public recrea-
tion potential of the WQJ^P will be assessed.
THE CITY OF TALLAHASSEE SPRAY IRRIGATION PROJECT
History of Irrigation at Tallahassee
Tallahassee's two treatment plants, the Lake Bradford Plant (h.5 MGD)
and the Dale Mabry Plant (0.5 MGD), were placed in operation during the
19^0's. Their effluent was discharged to a natural drainage stream which
flows into Lake Munson. Since this stream also receives most of the storm
runoff water from the city, during the past thirty years it has become
heavily laden with silt and shows the typical signs of accelerating
-------
IT
eutrophication. Because no rivers flow through Tallahassee, a city-
located sixteen miles from the coast, Lake Munson is the only receiving
water within Tallanassee's major drainage basin. Therefore, it will
continue to receive runoff water and any treated wastewater which is
discharged to a surface stream (Figure 3).
In 1961 the city placed in operation a 60,000 GPD high-rate trickling
filter plant to serve the municipal airport. Over a 6 month period during
1961-1962, field experiments at this plant demonstrated that the effluent
could be satisfactorily disposed of on land by irrigating at the rate of
h inches per day over 8 hours.
When Tallahassee's two plants reached their planned capacity in 1965 ,
the new southwest wastewater treatment plant was constructed near the
airport where soil and groundwater conditions were similar to the experi-
mental irrigation plot. The high rate trickling filter plant has a
comminuter, degritter, primary clairfier, trickling filter, final clarifier,
chlorine contact tank, holding pond, a wastewater irrigation field and a
surface outlet to Lake Munson. Florida state law requires that treated
effluent be chlorinated before it is released into receiving waters or
applied to the land by spray irrigation. Because local citizens have
continued to complain about the appearance of Lake Munson, the City is in
the process of developing an alternative 850 acre effluent disposal site
1.5 miles north of the lake where land irrigation of the entire combined
flow of 11 MGD has been shown to be feasible. The Bureau of Sanitary
Engineering, Florida State Board of Health, permitted one MGD effluent
spray irrigation system in lieu of the surface outlet. If this irrigation
system proves satisfactory, permission for additional irrigation capacity
is to be granted. The system has been operating continuously since the
initial flow of 0.25 MGD began in the summer of 1966. Daily flows were
gradually increased to 1 MGD by the summer of 1969. Plant effluent BOD
and suspended solids averaged 15-20 ppm during this period.
Plans called for the effluent to flow through the holding pond and
be applied to the irrigation fields on an "as need" basis to control the
pond water level. After six months operation, less than one-third of the
holding pond bottom had become wetted, so none of the effluent was avail-
able for irrigation. The pond was then by-passed, and during the spring
of 1967 the plant effluent was applied directly to the irrigation plots.
In 1972 the Environmental Protection Agency funded a three year =:.-\udy
to be conducted by Dr. A. R. Overman, the Department of Agricultural
Engineering at the University of Florida. Various crop responses are
being determined as a function of the wastewater loading and the ground-
water quality is being monitored. This research will provide design and
operational criteria for other Florida municipalities as well as Tallahassee.
THE TALLAHASSEE FACILITY AMD ITS OPERATION
Site Selection
The treatment plant is located on land which was once part of the
Apalachicola National Forest. Geologically, it is part of Lake Munson
Hills, a forty square mile area at the western edge of the Woodville
Karst Plain. The 200 acre plant site is 50 to 70 feet above mean sea
level, and the normal static water level is Uo feet below ground surface.
-------
850 ACRE
SPRAY
IRRIGATION
SITE
LAKE BRADFORD
TREATMENT
PLANT
4.5 MGD
DALE MABRY
TREATMENT PLANT
0.5 MGD
TALLAHASSEE
WELLS
MONITORING
AIRPORT
TREATMENT
PLANT
BLACK
SWAMP
006 MGD
PUMPING
STATION
LAKE
BRADFORD
mm
mBm i
mm i
CAPITOL
CIRCLE
P U IS R E LS n K a Hi U CI L] Cl Q Q
OO *G
~V°
'WMm.
TALLAHASSEE
MUNICIPAL AIRPORT
o
PIPELINE
SOUTHWEST
TREATMENT PLANT
SPRAY IRRIGATION
6.5 MGD O
LAKE
MUNSON
J
APALACHICOL A
NATIONAL
FOREST
a
/
/
FIGURE 3
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19
The soil is mostly Lakeland fine quartz sand with a depth to water
table and limestone aquifer of approximately 50 feet. This soil typically
has an infiltration capacity of 3-^+ inches per hour. Usually it has one
to two percent organic matter and less than five percent clay. The low
natural fertility of the soil is reflected in the native vegetation.
Besides scrub oak and similar plants, slash pine grow rather slowly in the
area. Furthermore, the soil has a poor moisture holding capacity with
an available water content of about 1 inch per foot of soil. The exten-
sive citrus farming in Central Florida demonstrates that these soils can
be very productive with proper fertilization and irrigation. Their deep
rooting zone and high permeability are conducive to intense production.
Sieve analyses on samples collected one foot below ground surface
show an average effective size of 0.15 mm and a uniformity coefficient
of 2.3. These characteristics provide an almost unlimited hydraulic
absorption capacity. This assures that flooding and the attendant runoff
will not be a problem.
Soil samples collected as drilling cores throughout the 200 acre site
show a general pattern of 20 to 25 feet of yellow quartz sand below the
surface. Under that is a clay lens varying in thickness from a few feet
to more than 10 feet followed by 10 to 12 feet of white quartz sand and
then limerock.
Pumping Station and Irrigation Field Layout
The pumping station that supplies the irrigation field is located
near the chlorine contact chamber. It was designed to pump effluent
into the wet pit from either the contact chamber or the holding pond.
When the flow from the contact chamber exceeded the pump capacity, the
excess spilled into the holding pond. The centrifugal pump was designed
for an output of 720 GPM at l60 feet of total head driven by a 50 HP, 3
phase motor. An inline meter measures how much effluent has beer; pumped
and automatically shuts it off at a predetermined number of gallons.
The irrigation pipe system is composed of 6 to 8 inch aluminum main
lines and 2 inch aluminum lateral lines. The sprinklers are spaced on
100 foot centers, and each one delivers i+5 GPM at an application rate of
0.1+5 inches per hour. The system was designed to operate at between 55
and 60 psi at the sprinkler head. The piping system is valved so that
sixteen sprinklers can be operated at one time to apply effluent at the
rate of approximately 1 MGD to 1+ acres. Altogether l6 acres are under
irrigation in four U-acre tracts. One or a combination of the four plots
can be sprinkled at any time. It was soon established that all sixteen
acres did not have to be irrigated simultaneously. Only 8 acres was
necessary for the one MGD flow except to observe how the grass responded
to municipal wastewater irrigation. To determine which grasses responded
best, the four plots were seeded with Pensacola Bahia, Argentina Bahia,
Centipede and mixed wild grasses.
In the spring of 1971 a by-pass line was completed from the Lake
Bradford Plant to carry the overload to the Southwest Plant. A gun type
sprinkler was then installed and positioned to irrigate both undisturbed
forest land and a plowed field. After seven continuous days of irrigation
at the rate of 250,000 gallons per acre per day, the forest land showed
no signs of ponding. However, the plowed ground commenced ponding after
the second day. Therefore, four big sprinkler guns were installed on U00
-------
20
foot centers in a rectangular plot to irrigate the forest land. Each gun
delivers 1060 GPM in a 555-foot circle. They are operated in pairs and
alternated every other day. Each pair of sprinklers applied 2 million
gallons daily. Neither the spray operation nor the residual field emit
much odor. Nor have there been any signs of solids building up on the
irrigation field surfaces.
Design Factors
At Tallahassee the design of this spray irrigation field has demon-
strated the reliability of both the equipment to move the effluent and
the irrigation field to accept it without ponding or runoff. Under the
initial experimental design the aluminum farm irrigation pipe was laid
on the surface so that it could be rerouted with a minimum of effort if
the system failed. The aluminum pipe has proven not to be completely
satisfactory because the exposed lines have been bent, broken or corroded
by external mechanical damage and internal wear from abrasion. Therefore,
underground cast iron pipe will be used when the irrigation field is
expanded. Alternate pumps are also being installed to eliminate down time
for pump repair unless both of them fail simultaneously.
Managerial procedures have evolved primarily from experience. The
system was designed so that fields can be dosed alternately, but the
appropriate dosing cycles had to be determined by operating the irrigation
fields in accordance with their immediate purpose. For example, if crops
are grown that only require mowing, the dosing periods can be much shorter
than if they require harvesting. The sprinkler heads were protected from
stoppages by placing a self-cleaning traveling screen with l/U-inch
openings in front of the pumps to remove suspended debris, and this
problem has very seldom arisen.
CHEMICAL, PHYSICAL AND BIOLOGICAL MONITORING
Selected chemical and biological parameters are monitored throughout
the system. The wastewater is tested for pH, chlorides, orthophosphate,
BODc-, COD, TOC, nitrate nitrogen, nitrite nitrogen, Kjeldahl nitrogen,
ammonia nitrogen, conductivity, total and fecal coliform. To determine
cause and effect relationships, groundwater samples from 23 monitor wells
undergo the same analytical tests as the effluent samples.
Soil solution sampling tubes were also installed throughout the
irrigation plots at depths ranging from 6 inches to 18 feet. The soil
solution was difficult to collect when the wells had low rates of loading
but not at high rates. At 300,000 gallons per acre per day loading rates,
laboratory analyses indicated that the concentration of orthophosphate
dropped from 25 ppm at the surface to 0.04 ppm at a depth of 10 feet.
Most of the ammonium nitrogen was converted to nitrate nitrogen in
the upper 2k inches of soil. At loading rates high enough to collect
solution samples in the 18-foot sample tube, there was no clear evidence
of denitrification or that the plants absorbed any appreciable amount of
nitrate nitrogen as the effluent percolated downward through the soil.
While density of fecal coliform bacteria in the influent was normally
in the range of lO^-io" per 100 ml, the density in water from the monitoring
-------
21
wells was usually zero or occasionally one or two bacteria per 100 ml.
Additionally, because the nearest residences were more than a mile away
from the well buffered spray irrigation site the aerosol viral and
bacterial hazard was considered to be minimal and was not monitored.
Effluent Characteristics
From a pollution standpoint the two primary mvtrients are nitrogen
and phosphorus. To calculate their loading rates, the effluent is assumed
to contain 25 ppm of total nitrogen (nitrate + ammonia + organic nitrogen)
and 10 ppm of total phosphorus. These values convert to loading rates of
5.7 lb of nitrogen per acre per inch and 2.3 lb of phosphorus per acre per
inch, respectively. Previous work.15 has shown that all nitrogen is con-
verted microbially to nitrate within the first 1 or 2 feet of well drained
soil. While microbial denitrification takes place, the extent of denitri-
fication has not been determined under effluent irrigation. Loading rates
for effluent containing the nitrogen and phosphorus concentrations noted
above are shown in Table V.
NITROGEN UPTAKE BY SELECTED GRASSES
Coastal Bermuda Grass - Rye Grass
l6
According to Burton's data , presented in Table VI, crop yields of
up to 10 tons of coastal bermuda grass per acre can reasonably be expected
to remove 1+50 lb of nitrogen per acre. Nitrogen uptake by rye grass can
be estimated from Overman's work^ presented in Table VII. Burton also
reported similar results.1° Therefore, based on crop yields of 3 tons
per acre, the removal of approximately 150 lb of nitrogen per acre appears
feasible. Thus, a crop rotation schedule of coastal bermuda grass in the
summer and rye grass in the winter can potentially remove about 600 lb of
nitrogen per acre per year. Assuming an irrigation rate of 3 inches per
week and 25 ppm nitrogen about 900 lb of nitrogen would be applied to the
soil. The combination would have a 67 percent recovery efficiency.
Coastal Bermuda Grass - Rye
Nitrogen uptake data for rye are presented in Tables II and III.
Assuming a crop yield of 2 tons per acre, a nitrogen uptake of approximately
200 lb per acre per year could be expected. Therefore, the coastal bermuda
grass-rye combination could be expected to utilize about 650 lb of nitrogen
per acre per year. With a nitrogen loading rate of 900 lb per acre per
/¦ear, the recovery efficiency would be 72 percent.
Residual Nitrogen
With a crop rotation of either coastal bermuda grass ana rye grass or
:oastal bermuda grass and rye, efficiency of nitrogen recovery would be
ipproximately 70 percent, leaving a,bout 7.5 ppm of residual nitrogen. Some
3f this remains in the root system of the plants and is released when the
'oots decay. Carbon is also released during microbial decomposition. It
ippears likely that some carbon moves down to the water table where it can
)e metabolized by denitrifying bacteria to convert nitrate ion to nitrogen
-------
22
TABLE V
Nitrogen and Phosphorus Loading Rates
Irrigation Rate Nitrogen Applied Phosphorus Applied
inches/week lb/acre/yr lb/acre/yr
1 300 120
2 600 2h0
3 900 360
1+ 1200 U80
TABLE VI
The Uptake of Nitrogen By Selected Grasses*
Nitrogen Dry Weight Nitrogen Nitrogen
Applied of Crop Content Harvested
(lb/acre) (ton/acre) (percent) (lb/acre)
COASTAL BEEMUDA GRASS**
300 9-6 1.3b 259
600 12.2 l.TU k2k
900 12.5 1.85 b66
RYE GRASS**
bOO 3.5 2.16 150
RYE**
*+00 2.8 3.39 189
* Adapted from G. W. Burton, 1973.
** For one cutting only.
-------
TABLE VII
The Uptake of Nitrogen Applied to the Soil in Wastewater by Rye and Rye Grass*
Rye Grass** Rye**
Irrigation Nitrogen Dry Weight Nitrogen Nitrogen Dry Weight Nitrogen Nitrogen
Rate Applied of Crop Content Harvested of Crop Content Harvested
(inches/week) (lb/acre) (ton/acre) (percent) (lb/acre) (ton/acre) (percent) (lb/acre)
0.25 12 1.06 1.97 1+7 0.60 1+.21 57
0.50 25 0.87 2.03 39 O.69 U. 6l 71
1.00 50 0.93 2.35 U9 0.90 1+.62 93
2.00 100 1.03 1.75 6U 1.00 U .79 107
-------
2k
gas which then escapes. If 10 percent of the original nitrogen were lost
by this process, then approximately 2.5 ppm would "be denitrified. Under
these conditions, no more than 5 ppm nitrate nitrogen would remain in ground-
water. The degree of denitrification under these conditions at Tallahassee
is not yet known.
PHOSPHORUS UPTAKE BY SELECTED GRASSES
Coastal Bermuda Grass - Rye Grass
Phosphorus uptake by coastal bermuda grass has been reported by Adams
et_ al. and some of their data are presented in Table VIII.-'-' Assuming a
crop yield of 10 tons per acre with a phosphorus content of 0.25 percent,
approximately 50 lb of phosphorus would be removed per acre per year.
Parks and Fisher-*-" reported the phosphorus content of rye grass to be
approximately 0.25 percent. With crop yields of 3.5 tons per acre about
18 lb of phosphorus would be removed per acre per year. Therefore, the
crop combination of coastal bermuda grass and rye grass would remove about
68 lb of phosphorus per acre per year. Since an irrigation rate of 3
inches per week of wastewater with a 10 ppm phosphorus concentration would
apply 360 lb per acre per year this combination would have a recovery
efficiency of 19 percent.
Coastal Bermuda Grass and Rye
The phosphorus uptake by rye is calculated to be approximately 1^4 lb
per acre per year based on a crop yield of 2.8 tons per acre (Table VI)
with a phosphorus content of 0.25 percent. The crop rotation combination
of coastal bermuda grass and rye would utilize approximately 6h lb per
acre per year of the 360 lb applied by spraying. This is equivalent to
an uptake efficiency for this combination of 18 percent.
Residual Phosphorus
Whereas nitrate is highly mobile in soil, phosphorus is readily fixed
as precipitates of aluminum, iron, and calcium. The fixation capacity of
Lakeland fine sand appears adequate for an estimated 75 year life span at
the Tallahassee site.
If 360 lb of phosphorus are applied to each acre of soil every year;
and only 20 percent of it is removed with the crops, a residual phosphorus
loading of 228 lb per acre would be added to the soil each year. The
fixation capacity of 23,250 lb phosphorus per acre to a 50 foot depth has
been calculated on the assumption that the soil have a bulk density of 1.70
gm/cm^ and can adsorb 100 ug of phosphorus per gm. Fiskell^ has shown
that for every 100 ug of phosphorus per gm of soil applied this same amount
is fixed, and that the solution would concentrate 1 ppm. Other values
are shown in Table IX.
Field measurements of phosphorus movement in Lakeland fine sand
showed that of 3,200 lb of phosphorus per acre applied over a 6 year
period, all of it remained in the upper 1+ feet of soil.1^ This would be
equivalent to U0,000 lb of phosphorus per acre per 50 feet, which corres-
ponds to the range shown in Table IX. Finally, it does not appear likely
that the fixation of phosphorus would cause soil clogging. For example,
fixation levels of 100, 200 and 300 ug phosphorus per gm of soil have
corresponded to mass increases of only 0.01, 0.02 and 0.03 percent.
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25
TABLE VIII
The Uptake of Phosphorus by Coastal Bermuda Grass*
Phosphorus
Applied
(lb/acre)
Phosphorus
Crop Content
(percent)
Phosphorus
Harvested
(lb/acre)
0
21
U2
8k
0.20
0.21
0.22
0.25
T
16
25
36
* Adapted from Adams et^ al_. , 1967 •
TABLE IX
Phosphorus Fixation by Lakeland Sand*
Solution Adsorbed Phosphorus Life of
Phosphorus Phosphorus Capacity Site**
(ppm) (ug/gm soil) (lb/acre/50 feet) (years)
1 100 23.000 75
5 200 U6,000 150
15 300 69,000 225
* Adapted from J. G. A. Fiskell and R. Ballard, 1973.
** Assuming 3 in/week, 10 ppm phosphorus and residual phosphorus of 288
lb/acre/year.
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26
CROP MANAGEMENT
Cover crop for the fields were planned for year-round yields, a
factor that is considerably more important in the northern than in the
southern regions of the state. Forage crops are commonly grown year-
round in the southeastern states. At Tallahassee a practical combination
is coastal bermuda grass (summer) and rye grass or rye (winter). Both of
them have shown excellent growth and production under proper fertilization
and irrigation. They have the best uptake of nitrogen among all crops
in common use today. Extensive information is available on their manage-
ment and utilization.
Overman's study^5 indicates that coastal bermuda grass inter-seeded
with winter rye will utilize 600 pounds of nitrogen per acre per year.
With 25 ppm as the concentration of total nitrogen, 2.0 inches per week
of effluent are required. This nitrogen will be removed from the site
when the crop is harvested. The phosphorus is expected to have minimal
agricultural use. However, the soils exhibit very high phosphorus
fixation capacities. Therefore, this mechanism will probably remove
almost all of the phosphorus.
Cropping Practices
To maximize crop yields from grass, it is very important to establish
a level sod. This enables the harvester to clip closely at fast ground
speeds without gouging the sod. A cutting height of approximately H inches
is recommended for both summer and winter crops. To avoid damage to
equipment, all tree roots and debris should be cleared from the land
before the grass is established. The land should also be disked thoroughly.
Grass should be planted on the site before any effluent is applied.
Otherwise, native grasses will grow and inhibit the establishment of a
uniform sod. This is particularly true for the summer season. Once
established, either coastal bermuda grass, rye grass or rye will provide
effective competition against weeds.
The summer coastal bermuda grass crop will have a growing season
from May until November. Either rye grass or rye can be overseeded for
a winter crop and will have a growing season from November until May.
The coastal "bermuda grass then will regenerate in May following the last
winter harvest.
A cutting frequency of 6 to 8 weeks is recommended. This should
provide a satisfactory balance between high yields on the one hand and
lodging on the other. The quality of forage should also be adequate with
this practice.
Irrigation Management
Experience has shown that to irrigate at a rate of 3 inches per week,
one continual application is more suitable than split applications as the
following analysis demonstrates.
Experiments at Tallahassee have shown that Lakeland sand drains to a
water tension of 60-70 cm. This corresponds to a water content of about
0.10. From experiments by Overman and West205 j_t may be deduced that at
an irrigation intensity of 0.5 inches per hour, the water content would
rise to approximately 0.25. Hence, during the 6 hour irrigation period,
-------
27
the 3 inches of effluent will "be distributed over a soil depth of approxi-
mately 12 inches (3 inches/0.25) and will gradually redistribute over a
depth of 30 inches (3 inches/0.10), which is still within the root zone
of these forage crops. This should allow adequate time for nutrient
uptake in the root zone.
There are advantages to using one application each week. Less effort
is required to rotate the valves. Problems with plant disease and lodging
are reduced by minimizing the time for wetting the crops. Finally,
harvesting operations are made smoother with fewer irrigations, and field
drying is also facilitated.
THE FLUSHING MEADOWS PROJECT
HISTORY OF THE FLUSHING MEADOWS PROJECT
The Salt River Valley in central Arizona is an irrigated agricultural
area undergoing rapid urbanization. An acre of urban land does not use
much less water than an acre of agricultural land. However, whereas the
agriculture is essentially consumptive, in the Salt River Valley about 50
percent of the water for urban use is returned as sewage. Approximately
two-thirds of the water for irrigation and municipal supplies comes from
surface reservoirs on the Salt and Verde Rivers. The remaining one-third
is supplied from groundwater, essentially a nonrenewable resource. While
this groundwater level is presently dropping at a rate of about 10 feet
per year, the depletion could be reduced if the groundwater could be
recharged with renovated wastewater from the sewage effluent.
The main sewage treatment plants in the valley are the Phoenix 91st
Ave and 23rd Ave plants. Both are activated sludge plants that discharge
their effluent into the Salt River bed. Their combined flow is presently
about 80 MGD. Each year, it increases by about 5 to 6 MGD, mainly due to
population growth. Thus, a flow of about 2U0 MGD or about 270,000 acre
feet per year can be expected by the year, 2000. At an application rate of It. 5
ft/acre/yr this source could irrigate some 60,000 acres of agricultural land.
In other words, at the current rate more water will be available for
irrigation than agricultural land will require to absorb it. The remaining
municipal effluent can be reclaimed for other purposes such as industry
and recreation.
To treat the effluent for unrestricted irrigation and recreation on
a large scale necessitates expanding the system beyond the present con-
ventional activated sludge process. According to Arizona standards^l
tertiary treatment is required to decrease the BODc and suspended solids
content to less than 10 ppm, and disinfectants must be applied as needed
to keep the fecal coliform density below 200 per 100 ml. Some of the
nitrogen should also be removed from the municipal effluent for large
scale irrigation to avoid undesirable effects on the crop quality or
harvesting schedule. The nitrogen and phosphorus also must be removed
if the effluent is used for recreational lakes. In a densely populated
region such as the Salt River Valley, large scale reuse of the effluent
requires that it be treated to be aesthetically acceptable.
Because the hydrogeologic conditions in the Salt River bed are
favorable for groundwater recharge by surface spreading, high rate
infiltration from basins in the river bed can produce a renovated
-------
28
effluent of the desired quality to be pumped out of the ground. To
investigate the feasibility of renovating the effluent in this manner,
a pilot project was constructed in 19&7 as a cooperative effort between
the U. S. Water Conservation Laboratory, the Salt River Project, and the
City of Phoenix. For the first three years, the project was partially
supported by a grant from the Environmental Protection Agency.
FLUSHING MEADOWS FACILITY AUD ITS OPERATION
Description of Pro ject
The pilot Flushing Meadows Project is located in the Salt River bed
about 1.^ miles downstream from the 91st Ave Sewage Treatment Plant.
Secondary effluent is pumped from the effluent channel into six parallel,
horizontal basins that are each 20 x TOO feet and 20 feet apart (Figure U).
Usually one foot of water is held in the basins by an overflow structure
at their lower end. The infiltration rate is measured from the difference
between the inflow and outflow rates by critical depth flumes at each end of the
basins.22 The infiltration rate for the 2 acre system is approximately 0.5 MGD.
Most of the soil in the basins is fine, loamy sand to a depth of
about three feet. Then coarse sand and gravel layers extend to about 250
feet where a clay layer forms the lower boundary of the aquifer.23-2^ The
static water table is at a depth of about 10 feet. Observation wells for
sampling groundwater and renovated sewage water were installed in a line
midway across the basin area (Figure U). All of the wells draw water from
a depth of 20 feet except the East Center Well and the West Center Well
which draw water from a depth of 30 and 100 feet, respectively.
Infiltration Rates
The infiltration rates in the basins generally decreased during
flooding, but the rate is restored during periods of drying.2^ Maximum
longterm infiltration or "hydraulic loading" was obtained with flooding
periods of about 20 days, alternated with drying periods of about 10 days
in the summer and 20 days in the winter. With this schedule, from 300 to U00
feet of water per yr have been infiltrated from an average depth of one foot.
At these rates 3 to ^ acres of infiltration basin are required for each
MGD of effluent.
Infiltration rates were higher in fully vegetated basins and lower in
a gravel covered basin than in a bare soil basin.However, since the
basins were flooded with a few inches of water for a few days in the spring
and early summer to allow the vegetation to develop, less water was infil-
trated in these basins than in the bare soil basin where greater water
depths and longer flooding periods were maintained during the entire year.
Thus, maximum hydraulic loading is probably obtained in nonvegetated basins
with water depths of several feet. If the suspended solids content of the
effluent can be kept below 20 ppm, little or no sludge accumulates on the
bottom of the "basins; and they can be operated for several years without
having to be cleaned. On the other hand, annual or more frequent removal
of accumulated solids is necessary if "the effluent has more than 20 ppm
of suspended solids.^5
-------
CONSTANT -HEAO
STRUCTURE
SUPPLY LINE
FLUME
«RAVEL OAM
WELL Nft-
/-PERMANENT
EFFLUENT POND
BASIN N*
i >—¦ ' * « « i I
SO 100 aitiri
_l_
J I
100 200
• WELL
300 f««t
DRAINAGE LINE
LINED
PONDS
UNLINED
-0 POND
EAST WELL
• •
Figure 4. Schematic of Flushing Meadows Project.
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30
Quality Improvement
Nitrogen. The average nitrogen content of the effluent is about 30
ppm. Almost all of it is in the ammonium form. Since the annual infil-
tration is about 300 feet, the nitrogen load of the system is in the order
of 30,000 lb per acre per year, much more than the few hundred pounds per
acre that can be removed from the soil each year by growing and harvesting
crops. These higher loads of nitrogen must be removed by biodenitrification
in the soil. Therefore, the system must be designed and managed to bring
nitrate and organic carbon together under anaerobic conditions. To do
this, the flooding and drying periods of the basins must be properly
scheduled.
The effect of the flooding schedule on the form and concentration of
the nitrogen in the renovated water is shown in Figure 5- It applies to
the renovated water from the East Center Well which is located in the
center of the basin area (Figure U) and obtains water from a depth of 30
feet. The renovated water from this well is mainly effluent that has been
infiltrated in basins 3 and U. This water travels underground for about
1+0 feet over 5 to 10 days.
With short, frequent inundations, from two to three days of flooding
and three to five days of drying, in July and August, almost all of the
nitrogen in the effluent was converted to nitrate in the renovated water.
With flooding and drying periods of several weeks each, such as from
September until January, the ammonium level in the renovated water was
not immediately affected; but the nitrate level was almost zero except
for a peak from>5 to ten days after the start of a new flooding period.
The nitrate peaks in October and December are recorded in Figure 5- The
low nitrate level in the renovated water during three week flooding
periods occurs because the oxygen is depleted in the soil and prevents
nitrification. Thus, the nitrogen stays in the ammonium form which can
be adsorbed by the cation-exchange complex of clay and organic matter
in the soil. This explains the low nitrate and ammonium levels in the
renovated water between October 20 and December 7 and after December 17
(Figure 5). When the flooding is stopped, drainage and drying below the
basins allows oxygen to enter the soil. Then the previously adsorbed
ammonium nitrifies. When flooding is resumed, the new water pushes the
nitrogen enriched capillary water down into the soil. As it infiltrates,
a nitrate peak occurs at the intake of the observation well five to ten
days after the start of a new flooding period.
During a long flooding period not all of the ammonium adsorbed on
the clay and organic matter is leached out in the nitrate peak when
flooding is resumed because part of what was nitrified from the adsorbed
ammonium during drying is again denitrified. This can take place during
the dry period and after flooding is started because the nitrate will
then move down into the anaerobic zones with the newly infiltrating
effluent. From the outlying observation wells where the nitrate peaks are
more dispersed, the overall nitrogen removal for the two to three week
flooding and drying periods was estimated to be about 30 percent. Figure
5 shows, however, that after the nitrate peak passes, the total nitrogen
level in the renovated water is nearly 90 percent less than that in the
effluent. The 30 percent overall nitrogen removal agrees with the results
of laboratory studies.
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40
INUNDATION PERIODS
TOTAL N OF EFFLUENT
NH4-N OF RENOVATED WATER
NO--N OF RENOVATED WATER
— o
—•
1968
ac
W 30
h-
_J
o
2
- 20
Z
UJ
e>
o
ct
z
OCT. NOV.
DEC.
AUG.
J-'i}',ure 5. Nitrogen in Secondary Sewage Effluent and in Renovated Water from East
Center Well-1968.
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32
When long flooding and drying periods stimulate nitrogen removal by
denitrification, care has to be taken that more ammonium is not adsorbed
by the soil during flooding than can be nitrified during drying.27 if
all the adsorbed ammonium is not nitrified during the drying cycle, the
cation exchange complex in the soil may become saturated with ammonium
during the subsequent flooding. This further reduces the adsorption of
ammonium. Consequently, its percentage will increase in the renovated
water. When this is observed, a sequence of short flooding periods, 2
days wet and 5 days dry for example, should be used to convert adsorbed
ammonium in the soil to the nitrate form. Some of these nitrates can
then be denitrified, particularly if a crop is grown. When the capacity
of the soil to adsorb ammonium is restored, longer flooding and drying
periods can be used again to maximize nitrogen removal.
Nearly all of the nitrogen in the effluent can be converted to the
nitrate form during short flooding periods when the effluent is used for
irrigation. Normally, several inches of water are applied every 2 or 3
weeks. With such an application schedule, aerobic conditions prevail in
the soil profile, and the nitrogen in the effluent is converted to the
nitrate form. Because the water moving downward from a root zone of an
irrigated crop has a salt concentration several times that of the irriga-
tion water2^, nitrate-nitrogen concentrations can be higher in the deep
percolation below sewage irrigated fields, can be higher than the total
nitrogen concentration in the sewage effluent itself. In fact, increased
nitrate levels in the groundwater below sewage irrigation fields are
commonly observed.29-30
Phosphate. The concentration of phosphorus measured as orthophos-
phate in the effluent was about 15 ppm in 1969- It decreased to around
10 ppm in 1970 and remained the same in 1971 and 1972. Perhaps it stabili-
zed because more low phosphate detergents were used. The renovated water
from the East Center Well contained about 50 percent less phosphate; and
Well 1, one hundred feet north of the basin area, had about 80 percent
(90 percent in 1972) less phosphate than the effluent. The renovated
water from Well 7, one hundred feet south of the basins, had somewhat
more phosphorus than Well 1. This may have been because Well 7 is much
more permeable and hence much coarser aquifer material than Well 1.2*+
The phosphate removal has been fairly constant over the more than 5
years the project has operated while a total of about 1^00 feet of effluent
were applied. Most of the phosphate is probably removed when the calcium
phosphate compounds precipitate in the soil and underlying sands and
gravels.
Fluoride. Normally, H to 5 PPm °f fluoride are present in the
effluent, and about 50 percent is removed from the renovated water from
the East Center Well and 70 percent from Well 1. This parallels the
phosphate removal and suggests that fluorapatities are formed in the soil.
Boron. The boron concentration of the effluent has increased from
about 0.It ppm in 1968 to about 0.8 ppm in 1971 and 1972. Boron is not
removed as the effluent moves through the sand and gravel layers of the
Salt River bed. Instead, it concentrates in excess of 0.5 PP"1 in irriga-
tion water and could affect the yield of some of the more boron sensit:ve
crops in sandy soils.31
Salts and pH. The total salt content of the effluent and of the
renovated water is usually in the 1,000 to 1,200 ppm range. Evaporation
from the basins would cause 'the salt concentration of the renovated water
-------
33
to be about 2 percent higher than that of the effluent. The pH of the
effluent is generally around 8, decreasing to about 7 as it becomes
renovated water.
Oxygen Demand. The BOD^ of the renovated water is usually less than
0.5 ppm compared with a range of 10 to 20 ppm for the effluent. The
total organic carbon content of the effluent ranges from 10 to 30 ppm,
and that of the renovated water is from 2 to 7 ppm. Thus, while the
suspended solids and biodegradable carbon are essentially all removed as
the effluent moves through the soil, some organic carbon still remains
in the renovated water.
Fecal Coliform Bacteria. The fecal coliform density in the effluent
is normally in the range of 105 to 10 per 100 ml. This is usually reduced
to about 0 to 10 per 100 ml in the renovated water from the East Center
Well although, occasionally, densities of several hundred per 100 ml have
been observed, particularly when newly infiltrated water reached the well
when a long flooding period began after a long drying period. The coli-
form density decreased as the renovated water traveled further underground.
No fecal coliforms have been detected after 300 feet of lateral movement
below the water table. Almost all of the coliform bacteria were removed
in the first 3 feet of soil.
OPERATIONAL SYSTEM AND ECONOMIC ASPECTS
To renovate the present flow of about 100 MGD from the two Phoenix
treatment plants, about 375 acres of infiltration basins would be required,
and this would have to be expanded to about -900 acres if the projected
2U0 MGD flow were renovated in the year 2,000. Infiltration basins could
be located along both sides of the Salt River bed, and the renovated water
could be pumped from wells in the center (Figure 6). This system should
be designed to avoid spreading the renovated water into the aquifer out-
side the Salt River >j*d, to insure a minimum under ground travel time of
several weeks an,d a distance of several hundred feet, and to keep the
water table from rising to more than about 5 feet below the bottom of the
basins during infiltration.The preceeding data indicate that such a
system would produce renovated water of more than sufficient quality to
permit unrestricted irrigation and recreation.
Tne hydraulic properties of the aquifer were evaluated with an
electric analog by measuring water levels in the observation wells after
infiltration,2^ On the basis of these data water table profiles and
underground detention times yere projected for the system (Figure 6) with
different model layouts of infiltration basins and wells.2^
The total cost to filter the effluent underground and the renovated
water out of the Salt River bed was estimated at about $5.00 per acre
foot32, or about $15.00 per million gallons in May, 1973, and today's
cost may be 50 percent higher. Nevertheless, this is still much less
than the cost of equivalent tertiary treatment at a conventional sewage
plant.
-------
R VER BED
INFILTRATION
BASINS "
WELL
WATER
TABLE
IMPERMEABLE
LAYER -
Figure 6. System of Infiltration Basins on Both Sides of River Bed and
Wells in Center for Pumping Renovated Water.
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35
THE PENNSYLVANIA STATE UNIVERSITY WASTEWATER
RENOVATION AND CONSERVATION PROJECT
History of Wastewater Irrigation at The Pennsylvania State University
The Pennsylvania State University Wastewater Renovation and Conserva-
tion Project was initiated in 1962 to evaluate alternative methods of
preventing further eutrophication of a stream that received effluent from
a sewage treatment plant. A group of scientists weighed a number of
alternatives including the feasibility and possible environmental impact
as well as the economics of applying treated municipal wastewater on the
land by spray irrigation. Other possible ways to protect the stream were:
to modify the existing sewage treatment plant to remove more phosphorus
and nitrogen, to dispose of the effluent in deep wells, or to construct
a new outfall to Bald Eagle Creek ten miles away for an estimated cost of
10 million dollars. Instead, wastewater renovation was combined with
conservation, and the term "Living Filter" was coined to describe the
concept of renovating and reusing municipal wastewater by land application.
Among the experts involved in planning the system were: agricultural,
civil, and sanitary engineers, as well as agronomists, biochemists,
ecologists, foresters, geologists, hydrologists, limnologists, micro-
biologists, and zoologists.
Initially, approximately 0.5 of the 3.7 MGD flow of the plant was
diverted to irrigate and fertilize crops and woodlots. In 1968 plans
were initiated to apply the entire plant flow of approximately h MGD to
the land. After a four year delay, the Living Filter system was expanded
to approximately 500 additional acres in the gameland area. However, the
capacity of the system was reduced to 3.0 MGD to stay within the allocated
budget because construction costs increased after this expansion was
proposed in 1968. Presently, most of the wastewater pumping plant and the
lb-inch steel force main to the gameland have been completed. The proposed
solid set irrigation system is projected to be in operation by the end of
1975 or the spring of 1976.
THE PENNSYLVANIA STATE UNIVERSITY FACILITY AND
ITS OPERATION
The sewage treatment plant located on the eastern edge of the campus
serves the university and much of the borough of State College. The waste-
water undergoes primary treatment and either trickling filter or activated
sludge secondary treatment. After secondary treatment the flows are
combined before chlorination. The average concentrations as well as the
minimum and maximum values for selected chemical parameters are reported
for 1971 in Table X.33 The last column in the table shows the value of
applying two inches of this wastewater per week as fertilizer.
The chlorinated secondary effluent is pumped through a 6-inch asbestos-
cement force main at a rate of 350 gpm (0.5 MGD) to either the agronomy
and forestry areas approximately 2.5 miles away or two miles further to
the gameland area. Since the agronomy and gameland spray areas are at
ground elevations 180 and 280 feet higher than the sewage treatment plant,
the effluent is pumped at 226 psi and delivered to the farthest distribution
head at approximately 40 psi#with correspondingly greater pressures at
locations closer to the pumping station (Figure 7).
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36
TABLE X
T"3
Chemical Composition of Sewage Effluent Applied During 1971
Constituent
Range
Minimum
Maximum
Average
Total Amount
Applied8-
mg/1
mg/1
mg/1
lbs/acre
pH
7.U
8.9
8.1
MBASb
0.03
0.88
0.37
5
Nitrate-N
2.6
17-5
8.6
128
Organic-N
0.0
7.0
2.k
36
NH^-N
0.0
5-0
0.9
13
Phosphorus
0.250
U.750
2.651
39
Calcium
23.1
27.8
25.2
375
Magnesium
9.1
15.1
12.9
192
Sodium
18.8
35.9
28.1
1+19
Boron
0.1k
0.27
0.21
3
Manganese
0.01
O.OU
0.02
0.2
8l •
Amount applied on areas which received two inches of effluent per week.
^Methylene blue active substance (detergent residue) values are for 1970,
constituent not included in analyses in 1971-
-------
THE PENNSYLVANIA STATE UNIVERSITY
WASTE WATER RENOVATION AND CONSERVATION RESEARCH PROJECT
GAMELAND AREA
WEATHER
STATE GAME LANDS
DO
~ ~
INFILTRATION
PONDS
TO UNIVERSITY
AIRPORT
^ AGRONOMY
AREA
FORESTRY
AREA
UNIVERSITY WELLS
ARMY RESERVE\\»
CENTER \V
WELL
1 MILE
tfL
BEAVER STADIUM
~ NITTANY
LION INN
OLO MAIN
SEWAGE T
PLANT »
TO SPRING CREEK
VIA THOMPSON RUN
DUCK
POND
CHLORINE
CONTACT
TANK
FIGURE 7
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35
Approximately 60 acres of crop and forest land with various kinds of
soil are irrigated with the wastewater. In the agronomy-forestry area the
soil layer ranges from a depth of 5 to 80 feet over a dolomite bedrock.
The clay-loam is less permeable than other soils nearby. In the forest.,
the mulch layer and undercover plants were not disturbed. The soil in the
gameland area is a deeper, sandy loam. Here, the soil overlay ranges from
20 to 160 feet above beds of sandstone, dolomite, and quartzite. The depth
of the groundwater varies from about 100 to 350 feet.
The solid set sprinkler irrigation system has a flexible design that
spaces the sprinklers from ^0 x 60 feet to 80 x 100 feet. After some
experimentation with application levels as high as 6 inches per week, most
of the spray irrigation has been applied at a level of 2 inches per week
in one continuous 12 hour period with 6.5 days between sprayings. This
application level was maintained because the flow remained well below the
infiltration capacity of the soil and also permits good renovation.
The spray irrigation areas are surrounded by a buffer zone but the
buffer distance varies and no attempt has been made to adhere to any
minimum buffer zone. In the gameland area some residences and a store
are less than 300 feet from a spray area. Additionally, a new community
called "Toftree" is located along the gameland property line and in
general proximity to the spray areas that will be used when the expanded
spray irrigation system becomes operational in early 1976. Opinions have
been expressed that aerosol pollution hazards are minimal or absent.1
CHEMICAL MONITORING
The chemical quality of a composite of the chlorinated, secondary
treated wastewater was analyzed as it was pumped through the sprinklers
during each irrigation sequence. The most consistently monitored chemical
parameters and their average concentrations measured for 1971 are presented
in Table X along with the range between minimum and maximum values.
As the wastewater percolated through the soil, changes in its quality
were measured by taking samples from suction lysimeters 6 inches to 15 feet
deep and from shallow monitoring wells 6 to 50 feet in depth. In addition,
deep wells (150-300 feet) were installed to monitor changes in the ground-
water aquifer that supplies potable water to the university.
SCOPE OF THE RESEARCH
Crop Responses to Wastewater Effluent
At Penn State the perennial grasses were the most suitable crops for
lands receiving wastewater effluent because of several factors. In
general, they have fiberous root systems and form sod that helps control
erosion and still allows a high rate of infiltration. The grasses are
also tolerant of a wide range of ecological conditions. They have a
high uptake of nutrients over a long period of growth. In 6 years 2127
pounds of nitrogen were applied to the reed canarygrass in 536 inches of
sewage effluent and sludge. Of this, 2071 pounds were removed in the
harvested crop, a 93 percent renovation efficiency. The average concentra-
tion of nitrate nitrogen was 3-5 ppm in the percolate at the h foot depth
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39
in the effluent irrigated areas and 0.2 ppm in the control areas. During
the same period of time, 797 pounds of phosphorus were applied in the
wastewater, and 279 pounds were removed when the crop was harvested. The
overall crop renovation efficiency was 35 percent for phosphorus. Individual
annual renovation efficiencies varied from 2k to 63 percent for phosphorus
removal by crops.3^
Forest Responses to Wastewater Effluent
The forests consisted of a red pine plantation (Firms resinoea) and a
sparse white spruce plantation (Piaea glauaa) as well as a mixed hardwood.
The spray application rate was 0.85 inch per hour while the level ranged
from 1 to 6 inches per week in spraying sequences that varied from 23
weeks during the growing season to one full year. The forested areas
were highly efficient in removing phosphorus. The forest biosystem decreased
the phosphorus concentrations more than 90 percent at the two foot depth
for all application levels. However, the forest bioeystem was not as
consistently efficient in reducing the nitrogen concentrations. A six
year average of the mean annual concentration of nitrate nitrogen was
collected at the U8 inch soil depth. Where varying total depths of waste-
water were received, the soil measured from 0.2 to 0.6 ppm in the control
areas and from 3.9 to 2k.h ppm of nitrate nitrogen in areas that received
two inches of effluent per week. The difference was due in part to the
organic character of the forest mulch which promotes a higher degree of
denitrification.
The growth of the trees varied considerably depending on the species
and level of application of the effluent. The white spruce and the young
hardwoods grew the most when they were irrigated at the level of two inches
per week. In general, hardwood forests are not as efficient as agronomic
crops to remove the nutrients. For example, a corn silage crop removed
1U5 percent of the nitrogen applied in the sewage effluent. In contrast,
the trees removed only 39 percent, and most of it was returned to the soil
in falling leaves. The silage corn crop also removed 1^3 percent of the
phosphorus from the sewage effluent3^~35 vhile the hardwoods removed only
19 percent.
Wildlife Besponse to Wastewater Effluent
The leader deer technique was initiated to determine the animal's
preference for or avoidance of irrigated areap. The deer grazed on
irrigated sites as readily as on the control sites, and in winter wild
deer rested and grazed within the ice covered areas that had been irrigated.
Moreover, in the irrigated areas the winter carrying capacity for rabbits
appeared to be much greater than in the control areas, presumably because
of improved living conditions in "caves" under ice covered brush. Here
they could also eat the terminal branches of the bent over brush. Rabbits
that were trapped in the irrigated areas were larger and healthier than
those taken in the control areas.36
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