LAND APPLICATION OF
WASTEWATER IN
AUSTRALIA
The Werribee Farm System
Melborne and Metropolitan Board of Works
Victoria, Australia
by
BELFORD L. SEABROOK
Professional Engineer
MAY 1975
US ENVIRONMENTAL PROTECTION AGENCY
Municipal Construction Division
Office of Water Program Operations
Washington, D.C. 20460
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ABBREVIATIONS
Board - MMBW-Melbourne and Metropolitan Board of Works
BOD - biochemical oxygen demand
cm - centimeter
COD - chemical oxygen demand
Farm - Werribee Farm soil treatment system of MMBW
in. - inch
MMBW - Melbourne and Metropolitan Board of Works
N - nitrogen
mgd - million gallons per day
mg/1 - milligrams per litter
ppm - parts per million
P - phosphorus
SS - suspended solids
TERMS
Conventional secondary treatment - Reduction of pollutant concen-
trations in waste-water by physical, chemical or biological menas.
Crop irrigation - Application on land of water to meet the growth
needs of plants.
Evapotranspiration - The unit amount of water used on a given area
in transpiration, building of plant tissue, and evaporated from ad-
jacent soil, snow, or intercepted precipitation in any specified time.
Grass filtration - Same as overland flow.
Land application or Land Treatment - The discharge of wastewater
onto the soil for treatment, reuse or crop irrigation.
Overland flow - Wastewater treatment by grass filtration, flooding
or spray-runoff, in which wastewater is applied onto gently sloping,
relatively impermeable soil which has been planted to vegetation.
Biological oxidation occurs as the wastewater flows over the ground
and makes contact with the biota in the vegetative litter.
Raw sewage - Untreated wastewater.
Secondary treatment - Something more than primary treatment,
usually treatment by physical, chemical, or biological means such
as trickling filters, activated sludge, or chemical precipitation
and filtration. Sometimes called mechanical treatment.
CONVERSIONS
1 Acre feet = 3, 060, 000 US gallons, or 2, 550, 000 Imperial gallons
A$ = Australian dollars
A$l. 00 - US $1. 35
US$1.00 = A$0.74- ,-. ~r
J. 0*317
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WESTEN
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CATCHMENT
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DANDENONG'7
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MELBOURNE
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5
PORT PHILLIP BAY
MELBOURNE AND METROPOLITAN AREA
- 2 -
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SUMMARY
This report concerns the Werribee Farm soil treatment
area operated by the Melbourne and Metropolitan Board of Works
(MMBW). The Board (MMBW) was constituted in 1890 by an Act
of the Parliment of Victoria to develop and operate a system of
main and general sewerage for the metropolis. James Mansergh,
an eminent sanitation engineer from London, submitted eight al-
ternative schemes, five of which involved treatment by land; two,
disposal by ocean outfall; and one, by chemical precipitation.
Mansergh stated that the Werribee site was situated for land puri-
fication of sewage because it was exceptionally dry and had an
abnormally low rainfall compared with surrounding districts. His
recommendation, based on proven success in England, and on the
benefit of irrigation in an area of low rainfall, was for disposal
by flood irrigation on prepared land without prior treatment of
the sewage. Even today raw sewage is used at the Werribee
Farm. Work began in 1892; and in 1897, the sewage from the
first property (a hotel) was delivered to the system. Mansergh,
of course, could not have foreseen Melbourne's rapid population
growth nor the demands that would be placed on the Werribee
Farm within 30 years of its establishment. By the late 1930's,
the heavy waste loadings had made it necessary to not only en-
large the area of the Farm, but also to complement land filtration
(called crop irrigation in the United States) with sedimentation,
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grass filtration (overland flow) and lagooning. Despite these ad-
ditions to the Farm's land treatment operations, the 1897 system
remains, to this day, basically as it was originally conceived
and build. Even the introduction of the South-Eastern Sewerage
System (in 1974) on the opposite side of Port Phillip Bay fulfills
Mansergh's original concept of a disposal system serving each
side of the Bay. The relationship of the Werribee Farm to the
South-Eastern Sewerage System can be seen on the accompanying
map of the Melbourne Metropolitan area. In June 1974, there were
some 800, 000 ratepayers (population 1, 880, 000) being served by
the Board. The Werribee Farm serves about 95 percent of the
sewered areas in the metropolis. The balance is served by four
other major and two minor systems.
For the fiscal year ending June 1974, the annual per capita
cost of the Board's Werribee system was A$1.13 (US$1. 53) for
95 percent of the population of 1, 880, 000. This figure includes
all current costs. The capital costs of the land and the original
construction were written off years ago. The average daily flow
to the Werribee Farm, is 125 million British Imperial gallons
(150 mgd US).
The principal problem with land treatment at MMBW is caused
by the increasing hydraulic load per capita coupled with the in-
creasing population served by the system.
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Because the cost of purification at Werribee is substantially less
than by mechanical treatment, as well as because the quality of the
effluent from Werribee is higher, the MMBW intends to continue to
utilize land treatment to the extent possible. However, as the popu-
lations of Melbourne and Geelong increase, and the urban areas extend
outward toward the Werribee Farm, the acquisition of additional land
adjacent to Werribee has not been possible. As a consequence, MMBW
is constructing conventional secondary mechanical treatment works and
plans to transfer about 45% of the hydrological load from the Werribee
Farm to the new South East mechanical system. In spite of this,
by 1980/81 the MMBW estimates that the pollutant loading will return
to the maximum that the Werribee Farm, as presently operated, can
handle.
Currently all sewage to the Werribee Farm is raw sewage. This
has been the practice since land treatment was started in 1897. How-
ever, in order to provide increased treatment capacity at Werribee,
MMBW is giving consideration to using a combination of part primary
to full secondary treatment in conjunction with biological processes.
In summary, the MMBW Werribee system is in full operation, is
most successful, is substantially lower in annual per capita cost of
operations, and MMBW intends to continue to operate its land treat-
ment facilities indefinitely.
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LAND TREATMENT IN UNITED STATES
The Federal Water Pollution Control Act Amendments of 1972
(Public Law 92-500), the legislative history of the Act, and the
regulations which have been issused in accordance with the pro-
visions of the Act, provide the statutory basis for consideration
and funding of land-application systems in the treatment of municipal
wastewater.
The rationale and goals within which land-application systems
are to be considered are contained in the following sections of the
Act:
Section 208 - Areawide Waste Treatment Management
Section 201 - Facilities Planning
Section 304 - Best Practicable Treatment Technology (BPT)
Section 212 - Cost Effectiveness Analysis
These sections, together with the regulations pertaining to these
sections of the Act, and the Program Memoranda to the EPA Regional
Administrators, have resulted in a growing interest in the United
States in soil treatment systems for municipal wastewater. The
EPA Deputy Administrator, on November 1, 1974, wrote to the
Regional Administrators urging them to ascertain that the regional
review of application for construction of publicly-owned treatment
works requires that land application of wastewater be considered
as an alternative waste management system. The DA said that the
RA's should refuse to fund projects using other systems of waste
treatment if it can be demonstrated that land treatment is the most
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cost-effective alternative; is consistent with the environmental
assessment; and, in other aspects, satisfies applicable tests.
This memorandum is attached hereto.
In addition to the potential for being the most cost effective
treatment alternative (note the MMBW total annual per capita cost
for the fiscal year ending June 1974 is US$1. 53 for sewage treat-
ment serving 95 percent of the population of 1. 88 million people),
another significant reason for the growing interest in land treat-
ment is that PL 92-500 gives authority to the EPA Construction
Grants Program to fund publicly-owned soil treatment systems
including the acquisition of the land that will be an integral part
of the treatment process -- Section 212(2)(A).
The EPA report, entitled, Survey of Facilities Using Land
Application of Wastewater by American Public Works Association,
identifies certain existing soil treatment systems that were started
in the United States as early as 1880. However, these early systems
started as disposal projects, and there is a major gap in reliable
design data and information. The consequences of this dearth of
design information has handicapped the construction grants pro-
gram, primarily because of the lack of standard criteria. Another
deterrent has been the lack of information concerning potential
health hazards from soil treatment systems.
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Strangely, however, the same dearth of information concerning
potential health hazards from secondary treatment and discharge
to surface waters has not slowed the demand for the more costly
conventional reinforced concrete treatment works. In fact, it seems
to me that there could be far greater health hazards from secondary
discharge into surface waters because these waters are so often used
as sources of potable water by other downstream municipalities.
INTRODUCTION
There are 17 residences located in the midst of the Werribee
Farm which are used by farm employees and their families. I visited
several of the homes of fa.rm employees, met members of their
families inchiding the children, and enjoyed a Sunday picnic on the
front lawn of one of these residences. There is no evidence of health
hazards caused by sewage irrigation in the adjacent fields, and no
concern was expressed by the occupants of these houses about po-
tential health hazards. To the foreign observer that I was, these
residences appeared no different than any other farm residences,
and their occupants appeared no different than any other farm families,
either in Australia or in the United States. Incidentally, on previous
trips to Australia I visited many rural communities in every
Australian state, except the Northern Territory, and I lived and
worked onfarms in the United States over a period of several decades.
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In my judgment, the farm houses located on the Werribee
Farm are better than the majority of farm dwellings in the
United States, and the occupants are living under better health
conditions than some of their counterparts in both Australia
and the U. S.
The Werribee Farm soil treatment system is the outstanding
project in Australia from the standpoints of the lowest annual
operating costs, success, size and extent of experience with the
use of wastewater effluents. The map of Melbourne on page 2
shows the relationship of the Board's Werribee Farm to Port
Phillip Bay and the surrounding Melbourne and Metropolitan
areas. The South-Eastern Purification Plant (secondary treat-
ment) is also shown on this map.
The Farm has served the residents of Melbourne as a re-
liable and economical means of wastewater treatment and utiliza-
tion since 1897. The use of wastewater for irrigation of pasture
land, and the subsequent production of cattle and sheep, is an
outstanding example of reclamation and conservation. Over the
years, however, population and industry have increased greatly.
As a result, the Farm is no longer able to cope satisfactorily
with the volumetric and organic loadings imposed upon it.
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LIVESTOCK AND THE TREATMENT PROCESS
The livestock at the Farm are not only money-earners from, the
point of view of meat, they are also an essential part of the treatment
operations.
Because wastewater treated at the Farm contains a high proportion
of natural fertilizers, it promotes a prolific growth of pasture; but
since crop irrigation is an efficient method only if the vegetation cover
is kept short, cattle and sheep are effectively used to "mow"the grass.
Sheep were introduced to the Farm in 1900 and cattle some 10 years
later. In the years since, the Board has sold more than 1.7 million
sheep and well over a quarter million head of beef cattle from its
Angus and Hereford herds.
Grazing of sheep is on a seasonal basis, and the Board buys the
animals in various parts of the southeastern corner of Australia to fatten
them for market. The beef cattle, on the other hand, are bred on the
Farm and remain the re until they are ready for sale. The most suitable
animals are retained for breeding and the others are sold as prime
meat on the hoof at Newmarket, Melbourne.
Sales of cattle are subject to the condition that they must be immed-
iately slaughtered at an abattoir in the Melbourne metropolitan area,
and those killed must undergo rigid inspection. This condition, imposed
in the 1920's by the Parliament of Victoria, was a political one obtained
by the commercial beef producers and had no health hazard basis.
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Diversion to the South Eastern Purification Plant of a portion of the
wastewater now reaching the Farm will ease, but not solve, the situation
for a number of years, but continued growth in the Western Catchment
will produce flows and loadings well in excess of those at present. For
example, the loading of biochemical oxygen demand will total about
750, 000 pounds per day before completion of the South Eastern Purifi-
cation Plant; diversion to that plant will remove slightly over 100, 000
pounds per day; increased development in the Western Catchment will
gain this amount back before 1985; and, less than fifty years hence, the
total loading may exceed 1, 000, 000 pounds per day.
The Farm system serves about 95 percent of the sewered areas in
the metropolis. Except for wastes from the greater part of the Munici-
pality of Sunshine, which are discharged directly in the Main Outfall
Sewer, and from Williamstown, which enter the main system at Spots-
wood, all wastes collected by the Farm system flow by gravity through
two main sewers - the North Yarra and the Hobsons Bay Main Sewers
which unite at Spots wood.
The combined flow then continues for 21/4 miles via a 9 ft. 3 in.
diameter trunk sewer which terminates at the Brooklyn pumping station.
Flows in this sewer enter the pumping station through two penstocks,
or control gates, set at the bottom of a well, 144 ft. deep and 22 ft.
in diameter. The penstocks control the flow into each of two protective
screen wells, 156 ft. deep and 22 ft. in diameter.
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From each screen well, the flow continues to its corresponding
pump well.
The two pump wells are each 178 ft. deep (internal) and 66 ft. in
diameter. Four pumps are installed in each well, and the eight pumps
are driven by individual electric motors, the combined rating of which
totals 12,800 horsepower. Each pump has a maximum capacity of
42 mgd (50 mgd, US).
When Melbourne's sewerage scheme was originally designed, Port
Phillip Bay was selected as the most suitable body of water for the
final disposal of the effluents after purification.
The most suitable method of purification known in European coun-
tries at the time was land treatment, and the site chosen near Werribee,
between the Geelong Road and Port Phillip Bay, possessed all the
factors essential for the satisfactory operation of the method--ample
area, reasonable isolation, suitable soil and climatic conditions.
An area of 8, 847 acres was acquired, and the preparatory work
began in 1893. As the city has grown, it has been necessary to expand
the Farm area, and today it covers 27, 000 acres or nearly 42 square
miles.
The Board's Farm at Werribee begain operating in 1897. By 1900,
it handled a wastewater flow averaging 12 million gallons per day (14.4
mgd, US). Since that time, the flow has increased as a result of
growth of population and industry in the metropolitan area, and at present,
averages about 125 mgd (150 mgd, US or 568,650 cubic meters). The
mode of operation, originally begun as irrigation of 6,000 acres of
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land to produce pasturage for cattle and sheep, has been expanded
over the years to include all-year use of anaerobic and aerobic lagoons,
sedimentation basins and open sludge digestion lagoons, as well as
overland flow (grass filtration) from mid-autumn to mid-spring when
irrigation demands are minimal or nil.
Rainfall at the Farm averages 19 in. (48. 3 cm. ) annually, of which
about 12. 5 in. (32. 2 cm. ) of evenly distributed rainfall can be expected
during the crop irrigation season; whereas, the evapotranspirational
potential during the same period averages about 35.6 in. (90.4 cm. ),
indicating that a major portion of the annual application of 44 in. (112
cm. ) of sewage effluent has evaporated. The daily flows of raw sewage
arriving at the Farm vary greatly depending upon rainfall. The current
average flow is about 150 mgd (568, 650 cubic meters); however, during
storm periods peak flows as high as 300 mgd (1, 140, 000 cubic meters)
may occur. Temperature variations are from a low of 40 degrees
F (4.4 degrees C) in winter to a high of 112 degrees F (44 degrees
C) in summer.
SOIL CHARACTERISTICS
There is no detailed classification of the Farm soils, but the surface
of the soil profile consists of a red-brown silt clay loam which is slightly
acid. Clay occurs at a depth of about 12 in. (30 cm. ). The depth of
the clay subsoil is substantial, extending far below any core samples
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that have been recorded. The report issued by the U. S. Army Corps
of Engineers in January 1974, entitled, "Selected Chemical Character-
istics of Soils, Forages, and Drainage Water from the Sewage Farm
Serving Melbourne, Australia", contains much detail on soil and forage
characteri stic s.
GENERAL OBSERVATIONS
Many aspects of the Farm operations are praiseworthy. Wide-
spread recognition of the need to conserve or reuse natural resources
has evolved only in recent years; however, since 1910 the Farm has
reused wastewaterfrom Melbourne for irrigation of pasture land. This
process has converted land of little potential for agriculture to prime
pasture which now carries over 20, 000 cattle and 10, 000 sheep. By
using the natural resources,, water and land, the Farm has marketed
more than 270, 000 cattle and 1, 500, 000 sheep since 1910. Taking into
account the equipment and manpower costs related to livestock pro-
duction, the net returns from sales presently average over A$500, 000
(US$675, 000) per year and significantly reduce the costs directly associ-
ated with sewage purification at the Farm. Thus, from conservation
and financial standpoints, the Farm represents a valuable resource
to the residents of Melbourne.
Initial diversions from the Farm system to the Board's South
Eastern Purification Plant are scheduled for 1975. Although this will
result in lower loadings at the Farm in the short-term, growth of popu-
lation and industry tributary to the Farm will generate additional load-
ings well in excess of those diverted.
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FARM OPERATIONS
It is logical to consider operations at the Farm from two stand-
points: first, in relation to its primary function for waste-water
treatment and second, in terms of its use for livestock production.
In addition, approximately three-fourths of the Farm area is a de-
clared Wildlife Sanctuary and provides a habitat for a variety of water-
fowl and other birds and animals.
WASTEWATER TREATMENT
In the early years, treatment at the Farm consisted of land fil-
tration by irrigation of pasture land with the underflow collected in
drainage channels and discharged to Port Phillip Bay. During winter,
wastewater flows in excess of the land's capacity were held in shallow
lagoons along the foreshore. Increasing flows during the intervening
70 years have lead to increasing the size of the Farm from about
6, 000 acres to nearly 27, 000 acres. Of this total, about 17, 000 acres
are used for some form of treatment, and the balance is devoted to
dry grazing, roads, buildings, yards, and other purposes.
The use of grass filtration (overland flow) during winter months
began about 1928 and made it possible to phase out the shallow lagoons
along the foreshore previously used for winter flows.
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Anaerobic and aerobic lagoons were introduced about 1935. Lagoons
can handle higher loadings of organic matter than either of the two ether
methods of treatment, and as a result, their area has been increased
greatly in recent years to match increases in loadings. For purposes
of comparison, numerical values for the years ending 30 June 1959
and 30 June 1971 are listed in Table A and the monthly variations during
each year are shown on Figures 1 and 2.
Table A. Loadings and Treatment Processes, 1959 and 1971
Year Ending 30 June
1959 1971
Total wastewater volume, milllion
gallons (US) 35,160 50,900
Average BODS, milligrams per liter
Pounds per day
Crop irrigation, million gallons (US)
Percent of total
Overland flow, million gallons (US)
Percent of total
Lagoons, million gallons (US)
Percent of total
451
384,000
13, 320
38
13,680
39
8, 160
23
588
661, 000
10,680
21
15, 360
30
24, 960
49
On arrival at the Farm, the wastewater is distributed to the various
treatment areas through a network of channels. Three methods of puri-
fication are used. Short explanations of each method along with perti-
nent comments follow.
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Crop Irrigation (land filtration). This is the primary method which
is used throughout the summer. The land filtration areas are carefully
prepared pastures, about 20 acres in exent, and divided into 50 bays
by low check banks. They are subsoiled, graded evenly and sown with
selected pasture grasses.
The wastewater is applied as in normal flood irrigation. Every
18-20 days, each block is covered to a depth of about 4 in. In all,
about 600 acres are irrigated each day. The wastewater filters through
the soil and when purified seeps into deep earth drains.
The periodic irrigation of pastures with wastes containing a large
proportion of fertilizing materials promotes a very vigorous growth of
grass. Rotational grazing by sheep, cattle and some horses is essential
to maintain these pastures in a condition suitable for continued waste-
water purification.
Application rates for crop irrigation are controlled by the ability of
the soil to absorb water, rather than by the strength of the wastewater.
Examination of irrigation records from 1935-1971 shows wastewater
irrigation depths average about 3. 5 feet per year and range between
2. 9 and 4. 2 feetper year. In a given year, the application rate depends
on the rainfall pattern and evaporation. Including annual rainfall, the
land receives more than 5 feet of water depth per year. Based on
present wastewater strength, the average application rate amounts
to 30 Ib. of BOD per acre each day.
Crop irrigation is quite effective in reducing the concentrations of
many chemical constituents of concern in terms of their effects on the
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receiving waters. Compounds of nitrogen, phosphorous, and most
of the heavy metals are reduced dramatically. Table B shows results
of analyses made on the incoming wastewater and the average for effluent
collected from seven different drainage channels which pick up the
underflow from the irrigation areas.
Table B. Chemical Characteristics of Untreated Wastewater and
Effluent from Crop Irrigation Treatment
T7
mg/L Concentrations
Constituent
Organic nitrogen
Ammoniacal nitrogen
Nitrite
Nitrate
Orthophosphate
Total Phosphorous
Sodium
Potassium
Calcium
Magnesium
Copper
Nickel
Chromium
Cadmium
Zinc
Lead
Mercury
Untreated
Wastewater
14.3
35.0
0.75
0
26.2
32. 1
400.0
95.0
65.0
80.0
0.45
0.20
1.0
0.01
1.3
0. 55
0.0015
Effluent
1.0
3.2
1.3
0.4
2.6
2.9
770.0
26.0
45.0
107.0
0.07
0.16
0.09
0.006
0.18
0.12
0.0003
Percent
Removal
93
91
-
90
91
73
30
84
20
90
40
86
78
80
Source: MMBW Analyses on samples collected 17 May 1972.
I/ Concentrations of nitrogen compounds expressed as N; phosphorous
~~ compounds as PO, ; all other as the particular element.
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Overland Flow (grass filtration). This process is used in purifying
the greater part of the normal winter flow when reduced evaporation
makes crop irrigation impractical. In this method, the wastewater is
first directed into sedimentation tanks, and when the sludge has settled,
the water is allowed to flow slowly but continuously over graded areas
on which Italian rye grass supplements the natural herbage to make
a dense growth. The plants act as a filter in which microorganisms
absorb the organic matter in the wastewater so that by the time it
reaches the drain, it has the required standard of purity. The overland
flow areas are grazed only in the summer when they are not needed
for purification purposes.
Detention times are about 2 days. In contrast with crop irrigation,
loading rates are governed by wastewater strength ratherthan by volume.
Because of the short detention time, daily loadings rather than long
term ones are important. Maximum loadings of about 90 Ib. of BOD per
acre each day can be handled. In practice, however, it is more con-
venient to control application by regulating wastewater volume to the
overland flow areas. To keep BOD loading rates within the maximum,
the volumetric rate of application of sedimented wastewater is held
at about 1 mgd per 50 acres. Experience at theWerribee Farm indicates
that daily BOD application rates average about 70 Ib. per acre.
Oxidation Ponds Treatment. This process operates throughout
the year to handle the balance of the normal flows which cannot be
treated by the other methods and also copes with the wet weather excess
flows. During this treatment, the wastes flow slowly through large
areas of shallow ponds where purification is effected by oxygen which
is partly absorbed from the atmosphere and partly provided by algae
in the presence of sunlight.
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Oxidation Ponds. In the lagoon treatment process, wastewater
passes through anaerobic lagoons and then through aerobic lagoons.
Detention times, relatively short in the former and long in the latter,
depend on the rate of wastewater addition, but generally are about
one month. BOD loading rates vary with Wastewater strength and the
volume added. Experience indicates that average loading rates of
about 60 Ib. of BOD per acre per day can be handled in winter, while
about 100 Ib. per day can be handled in summer when photo synthetic
activity is greater due to higher temperatures and longer hours of
sunlight.
Treatment Efficiency. As shown by the annual averages on Table
C, the three treatment processes vary in their ability to remove
organic matter and other chemical constituents in raw wastewater.
The crop irrigation process is the most effective, but as noted above,
area loading rates are low and only about 20 percent of the year's
flow at the Farm can be treated by this process. The reductions
it achieves in compounds of nitrogen and phosphorous are particularly
noteworthy. In raw wastewater given crop irrigation treatment, only
5pounds pass through the top soil and are found in the effluent.
In contrast, the comparable values for overland flow are 40 pounds
of nitrogen and 65 pounds of phosphorous, while for lagoons, the
values are 65 and 70 pounds respectively. In terms of nitrogen
removal, crop irrigation is 8 times more effective than overland flow
and 13 times more effective than lagoons. Similarly, for phosphorous
removal, it is 13 and 14 times more effective, according to MMBW.
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Table C. Estimated Performance by Treatment Processes
on Annual Basis
Characteristics
Percent of total flow
treated
Percent removal
BOD
Suspended solids
Total nitrogen
Total phosphorous
Detergent
E. Coli
Method of Treatment
Crop Irrigation
20
98
97
95
95
80
98
Overland Flow
30
96
95
60
35
50
99. 5
Lagoon System
50
94
87
40
30
30
99.8
Odors. Sources of odors at the Farm have been studied intensively
several times, particularly in 1950, 1966, and 1968-1970. The 1966
work disclosed that the "odor potential", based on measured hydrogen
sulphide emissions, was four times greater in winter than in summer,
and that sedimentation and sludge digestion basins, lagoons, and over-
land flow areas were the principal sources. Crop irrigation areas
and effluent channels were found to be relatively insignificant sources.
At each of the major sources, the treatment processes are, or are
prone to be, anaerobic. Sedimentation and sludge digestion basins
are open, and hydrogen sulphide and other odorous gases are readily
released to the atmosphere. The anaerobic lagoons, an inherent part
of the lagoon system presently used, are economic on space due to
the high BOD loading which they can handle, but are the odorous
component. During winter, the area of anaerobic lagoons is greater
than in summer, which leads to the release of greater quantities of
hydrogen sulphide. In the 1966 tests, this gas was detected over
about half of the area used for overland flow.
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Livestock Production. Sincel910, the Farm has operated a commercial
beef enterprise, producing 20-22 month old steers and fat cull cows
for the Melbourne market. During the past 62 years, over 270,000
cattle have been marketed. Since 1946, almost the entire cattle output
has been bred and raised on the Farm. In addition, sheep are brought
in and fattened on the Farm, and during the same period, more than
1. 5 million have been marketed.
Early prohibitions against marketing the cattle for human con-
sumption because of the incidence of beef measles (cysticercosis)
were overcome in 1946 by the adoption of the carcass inspection and
branding program. In addition, the Farm stock has built up an im-
munity, and market rejection for this reason is rare --29 rejections
out of over 116,000 cattle marketed since 1946.
In summary, the principal purposes of operating the Werribee
Farm have been to renovate the sewage effluents and to recover re-
sources that could be converted into cash. Research for the sake
of research alone has not been a major factor, although some elements
of research have been done to seek out solutions to specific problems.
The Werribee Farm has 31 test wells for monitoring the influent
(daily) and the effluent (twice weekly) to Port Phillip Bay.
The Board has some information on soil analyses at certain loca-
tions. In certain small areas affected by salt accumulation caused
by groundwater, there is some information. There is limited data
on receiving water quality, odors, and potential health hazards, as
well as information on BOD, SS, COD, pH, fecal coli, P, total N,
nitrate, nitrite and Cl.
-24-
-------
CORPS OF ENGINEERS REPORT
In May 1972 a team from the U. S. Army Corp of Engineers
made an intensive inspection and study of the Werribee Farm
land treatment system. An important aspect, among others,
was to learn as much as possible about long term responses
of the soil/plant ecosystem to sewage applications. Accordingly,
soil and plant samples were collected and analyzed for their
nutrient and heavy metal contents.
A report published by the Corps in January 1974, entitled,
"Selected Chemical Characteristics of Soils, Forages, and
Drainage Water from the Sewage Farm Serving Melbourne,
Australia", presents and discusses the findings of this study.
Specifically, data resulting from the analyses of soil and plant
samples, from sites under irrigation for periods of 48 to 73
years, is discussed in relation to a control sample, length
of time under irrigation, resultant water quality produced by the
treatment system, and expected ranges of constituent concen-
trations found in soils and plants from the literature on the
subject. A copy of the Corps report is attached hereto.
-25-
-------
MOVIE
The MMBW has produced a 16mm film, entitled Werribee - In
Harmony with Nature, showing the land treatment operations at the
Werribee Farm, This is a nontechnical film, 773 ft. in length. Copies
can be purchased from the MMBW. EPA has ordered 10 copies of
this film, one for each Regional Office. Persons wishing to buy a
copy should address their inquiries to James B. McPherson, Manager,
Werribee Farm, Melbourne and Metropolitan Board of Works, 625
Little Collins Street, Melbourne, Victoria 3001, Australia.
-26-
-------
REFERENCES
1. Melbourne and Metropolitan Board of Works, Reports, Publicity
Brochures, Newsletters, Staff Newspaper, Unpublished Memoranda,
Calculations, Lists, Fact Sheets, Charts, Sewerage Committee
Notes, Board of Works Notice Papers, and Interviews with Board
Officials, Employees and Specialists.
2. Survey of Facilities Using Land Application of Wastewater, Prepared
by American Public Works Association, July 1973. No. EPA-
430/9-73-006. National Technical Information Service No.
PB-227-351-A/S. U. S. Government Printing Office Stock No.
5501-00666; Cat. No. EP2.2:W28/4.
3. Article, Waste into Wealth, Water Spectrum 1972.
4. Report, Program for Development of a Master Plan for Water Quality
Management at the Board's Farm, March 1973, by Caldwell
Conn ell Engineers.
5. Data and statistics from certain Principal Persons Interviewed.
6. Data and statistics from Dr. Thomas D. Hinesly, University of
Illinois.
7. Notes from personal observations during site visits.
ATTACHMENTS
1. Memorandum from EPA Deputy Administrator to RA's, Nov. 1, 1974.
2. Report, U.S. Army Corps of Engineers, January 1974 "Selected
Chemical Characteristics of Soils, Forages, and Drainage Water
from the Sewage Farm Serving Melbourne, Australia".
-27-
-------
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
SUBJECT: Land Treatment
DATE: November 1, 1974
FROM: Deputy Administrator 1st John Quarles
TO: Regional Administrators
The purpose of this memorandum is to express my concern that
EPA must do a better job in assuring that land treatment is given
full and adequate consideration as a possible method for municipal
sewage treatment in projects funded with Federal grants.
Land application of wastewaters is practiced successfully and
extensively in the United States. Many land treatment systems
have been in continuous use since 1900. It is apparent from this
long-term experience and documented research work that land treat-
ment technology is a viable alternative to be considered as part of
waste management systems.
In section 201 of the Federal Water Pollution Control Act
Amendments of 1972, it declares that:
"Waste treatment management plans and practices shall
provide for the application of the best practical waste
treatment technology before any discharge into receiving
waters, including reclaiming and recycling of water, and
confined disposal of pollutants so they will not migrate to
cause water or other environmental pollution and shall
provide for consideration of advance waste treatment
techniques".
Pursuant to section 304(d)(2), which directs EPA to publish in-
formation on alternative treatment management techniques and systems
available to implement section 201, the document "Alternative Waste
Management Techniques for Best Practicable Waste Treatment" was
published. Therein it considers land application as a viable
alternative for best practicable waste treatment.
In addition, the Cost-Effectiveness Analysis Regulations
which apply to all projects subject to best practicable treatment
state that:
"All feasible alternative waste management systems
shall be initially identified. These alternatives should
include systems discharging to receiving waters, systems
using land or surface disposal techniques, and systems
employing the reuse of waste water".
EPA Form 1320-6 (Rev. 6-72)
-------
- 2 -
The above requirements shall be met for all projects awarded
after June 30, 1974. This means that land treatment must be con-
sidered in the basic selection of method for waste treatment.
I urge that you ascertain that your regional review of appli-
cation for construction of publicly-owned treatment works require that
land application be considered as an alternative waste management
system. If it can be demonstrated that land treatment is the most
cost-effective alternative, is consistent with the environmental as-
sessment, and in other aspects satisfies applicable tests, the Region
should insist that land treatment be used and should refuse to fund
projects using other systems of waste treatment.
Your director of Water Programs Division has received the draft
document "Evaluation of Land Application Systems". This document
should be utilized during the review process. Additional assistance
can be obtained by contacting the Municipal Construction Division
(OWPO), the Municipal Technology Division (ORD), or the Robert
S. Kerr Laboratory (ORD).
In order to promulgate proper consideration of land treatment
systems by future grant applicants I suggest that the Regional Office
provide opportunity for public awareness of land treatment tech-
nology. As an example, Region III is planning a two day symposium
November 20-21, 1974 at the University of Delaware to highlight
land application technology. The idea for the symposium originated
in the Regional Office and was planned cooperatively between the
regional staff and Office of Water Program Operations headquarters
staff. The objective of the symposium is to clarify the technical and
policy issues involved and to chart directions for future decisions
on land treatment techniques. The symposium will provide useful
information to over 300 engineers, scientists, public officials and
private citizens. This technique or a similar one could be used by
your region to emphasize consideration of land treatment.
-------
-------
Attachment 2 - Werribee
selected chemical characteristics
of soils, forages, and drainage water
from the sewage farm serving
m el bourne, australia
prepared for Department of the Army, Corps of Engineers
-------
selected chemical characteristics
of soils, forages, and drainage water
from the sewage farm serving
melbourne, australia
prepared for
Department of the Army, Corps of Engineers
-------
-------
SELECTED CHEMICAL CHARACTERISTICS OF SOILS, FORAGES,
AND DRAINAGE WATER FROM THE SEWAGE FARM SERVING
MELBOURNE, AUSTRALIA
Contributing Authors
Lt. Richard D. Johnson, Corps of Engineers
Robert L. Jones, University of Illinois
Thomas D. Hinesly, University of Illinois
D. J. David, CSIRO, Australia
January 1974
Prepared for
DEPARTMENT OF THE ARMY
Corps of Engineers
The findings in this report are not to be construed as an
official Department of the Army position unless so designated
by other authorized documents.
-------
-------
INTRODUCTION
During 1971 the U0 S. Army Corps of Engineers embarked upon
the new mission of assessing wastewater treatment technology and
planning for regional wastewater management systems. The policy
was adopted that the Corps would develop several alternative
wastewater management plans incorporating advanced-biological,
independent physical-chemical, and land treatment technologies.
The alternative plans were developed emphasizing the technical
goals of producing a high quality of water, i.e., "no discharge
of pollutants", and incorporating wastewater reuse, while main-
taining an active program of public involvement and education.
These plans would then be provided to the public and local
decision-makers as viable alternatives to meeting the high water
quality goals as required by Amendments to the Federal Water
Pollution Control Act, PL 92-500, October 1972.
During the course of the Corps' Wastewater Management
Planning Studies many questions and concerns were raised about
the state-of-the-art concerning land treatment technology.
Specifically, questions were being asked of the Corps such as:
(1) What are the long-term responses of a land
treatment system?
(2) Will a land treatment system produce the desired
renovated water quality?
-------
(3) What are the effects of excess water, nutrients,
and heavy metals on the soil and plant environments?
(4) What are the public health aspects associated with
land treatment systems?
(5) Where can one find operating land treatment systems?
Therefore, in an effort to answer some of these questions and better
support its planning responsibility, the Corps of Engineers sponsored
an inspection trip to the Board of Works Farm, Melbourne, Australia,
where raw sewage has been irrigated over a 70-year period. The study
team, including agronomists, planners, and engineers under the direc-
tion of Major General Willard Roper, Special Assistant to Director
of Civil Works for Water Management, Office of Chief of Engineers,
U. S. Army, made an intensive inspection and study of the Melbourne
system during the week of Ifi May 1972.
One important aspect of this inspection trip was to learn as
much as possible about long-term responses of the soil/plant
ecosystem to sewage applications. Accordingly, soil and plant
samples were collected and analyzed for their nutrient and heavy
metal contents. The purpose of this report is to present and discuss
the findings of this study. Specifically, data resulting from the
analyses of soil and plant samples from sites under irrigation for
periods of 48 to 73 years will be discussed in relation to a control
sample, length of time under irrigation, resultant water quality
produced by the treatment system, and expected ranges of constituent
concentrations found in soils and plants from the literature.
-------
BACKGROUND
The Board of Works Farm at Werribee was established in 1897,
and currently receives raw sewage generated by the 2.5 million
people of metropolitan Melbourne, Australia. Contributions to the
sewage flow include domestic wastes, industrial wastes, urban storm
runoff, and ground water infiltration. The daily amounts of sewage
arriving at the Farm vary greatly depending upon rainfall. The
o
current average flow is about 546,000m /day (144 MGD), however,
peak flows as high as 1,140,000m 3/day (300 MGD) during storm periods
occur.
Rainfall at the Farm averages 48.3 cm (19 in.) annually of
which about 32.2 cm (12.5 in.) of evenly distributed rainfall can
be expected during the irrigation season, whereas, the evapotran-
spirational potential during the same period averages about 90.4 cm
(35.6 in.), suggesting that a major portion of the annual applica-
tion of 112 cm (44 in.) of sewage water is evaporated.
The Board of Works system utilizes three different treatment
processes at various times of the year. Land filtration (irrigated
permanent pasture), the principal treatment method used throughout
the six to seven month summer season, encompasses 4,200 ha (10,376
A) of the total farm and treats about 273,000m 3/day(72 MGD). This
process, which is a flood irrigation system using check borders,
allows wastewater to percolate through the soil and subsequently
-------
to be collected in deep, open drains or ditches. In 1897 the land
filtration area was divided into 8.1 ha (20 A) paddocks consisting
of many individual bays which are still being used today. Each bay
is 0.16 ha (0.4 A) in extent, and surrounded by low check banks to
permit a 10 cm (4 in.) application of water without run-off.
Initially these bays were deep-plowed to a depth of 76 cm (30 in.)
to break up the less permeable subsoil. The irrigation paddocks
are sown with a mixture of grasses and legumes to provide balanced
pasture production throughout the year. Some of the sewage arriving
at the Farm goes through a primary treatment process of sedimenta-
tion providing several hours of detention. However, part of the
older land-filtration area of the Farm is irrigated with raw sewage
without prior sedimentation. Sewage is applied every 18 to 20 days
with each block covered to a depth of about 10 cm (4 in.). In all,
approximately 243 ha (600 A) are irrigated each day.
The other two treatment methods consist of "grass filtration"
(overland flow) which is used in the winter time in lieu of land
filtration, and oxidation ponds to handle the balance of the normal
flow and wet weather excess. The processes occupy 1405 ha (3472 A)
and 1375 ha (3393 A), respectively, while 2,830 ha (7000 A) of
the Farm are reserved for dry grazing of livestock. Since these
two processes were not specifically the subject of this investiga-
tion, they will not be discussed further.
-------
2 2
The Farm now includes 109 km (42 mi ), of which about 70
2 2
km (27 mi ) is devoted primarily to sewage treatment. The 109
2
km of agricultural land is being used to support a large livestock
grazing operation including cattle and sheep.
-------
Soil and Forage Characteristics
Much of the Board of Works Farm is situated on soils derived
from either Pleistocene basalt or Pleistocene riverine sediments,
which are somewhat variable. The investigations presented in this
report are confined to the older part of the Farm which is almost
entirely Pleistocene alluvium of the Werribee Series (See Figure 1).
These sediments are derived from weathering products of Pleistocene
basalt.
Although no detailed classification or mapping has been carried
out for the Farm soils, Skene (27) has completed a survey of irri-
gated soils at the Farm. Typically, the surface of the soil
profile consists of a red-brown silty clay loam which is slightly
acid. Calcareous silty clay occurs at a depth of about 30 cm where
the exchange complex of the clay becomes increasingly dominated by
exchangeable Mg and Na with depth. From particle size
distribution analyses of six core samples it was found that the
soils averaged about 35 percent clay, 45 percent silt, and 20 percent
sand. The upper 30.5 to 91.5 cm of the soil showed liquid limits
ranging from 32 to 41 (average about 37) and plastic limits ranging
from 13 to 22. While the profile is only slowly permeable, the soil
can take about 2 cm of water a day. A mixture of grasses includes
perennial rye (Lolium pratense), Italian rye (L. multiflorum), white
clover (Trifolium repens), strawberry clover (T. fragiferum), alsike
clover (T_. hybridum) , cocksfoot (Dactylis glomerata), timothy
-------
(Phieuro pratense), and meadow fescue (Festuca elatior).
Perennial rye grass dominates most of the irrigated land, but in
successively wetter spots there is marine barley grass (Hordeum
marinum) and docks, with water couch (Agropyron repens) in the
wettest spots. Under irrigation and with grazing a 2- to 5-cm
thick layer of loam rich in organic matter has developed on the
*
surface (20).
Wastewater Characteristics
Selected chemical and biological characteristics of raw
sewage received at the Board of Works Farm in recent time are
presented in Table 1. These results represent data extracted
from reports of analyses of 24-hour composite samples obtained one
day each month over a 13 month period (May 1970 through May 1971).
The effluent, as it arrives at the Farm, is approximately twice as
strong as we have identified in the United States. The principal
reason for this is the relatively low per capita use of water in
3
Melbourne, which is about 0.032m /day (84 gallons per day) at
the present time.
References are at the end of report
-------
Table 1. Composition of raw sewage received at the
Board of Works Farm during the period May
1970 through May 1971, in ppm (24 hour
composites taken one day each month).
Constituent
Total solids
Volatile solids
Suspended solids
Total nitrogen
Total phosphorus as PO,
Total chloride (as Cl)
BOD (5 days @ 20° C)
Average concentrations of certain heavy metals in raw sewage from
analyses of 24-hour composite samples taken during routine sampling
one day in each month from June 1968 through November 1969 (composites
prepared from grab samples taken at hourly intervals) are presented
in Table 2.
Number of
samples
13
13
12
13
12
9
12
Mean
1788
756
473
67.9
34.5
654
578
Standard
deviation
515
244
70
13.0
3.5
25
80
-------
Table 2. Heavy metals in raw sewage during the period
June 1968 through November 1969, in ppm
(24-hour composites taken one day each month).
Heavy Metal
Ni
Cu
Zn
Cd
Cr
Pb
Number of
Samples
13
15
10
3
15
1
Mean
..»
0.20
0.64
1.00
0.07<1>
0.55
0.55(1)
Standard
Deviation
0.091
0.17
0.58
--
0.21
« H
-' Includes or is sample of 17 May 1972.
Data presented in Tables 1 and 2 provide some information regarding
the quality of wastewater that is being applied to the land filtra-
tion areas today. The authors have no information on how these
data compare with the sewage quality applied over the 70-year
history of the site.
-------
-------
PROCEDURE
As previously stated, one of the primary purposes for the
Corps of Engineers visiting the Board of Works Farm was to assess
the long-term response of soils and plants to nutrients and heavy
metals applied as constituents of the sewage used for irrigation.
To help identify these responses, T. D. Hinesly and T. W. Whitman
as members of the Corps inspection team collected soil, water,
and plant samples for laboratory analyses and available historical
data. Significant raw sewage quality data have previously been
presented. Also use was made of two unpublished reports prepared
by V. G. Anderson in 1924 for D. Avery (hereafter referred to as
the Avery-Anderson report), who was the advising chemist to the
Board. These reports presented results of a chemical examination
of raw sewage, soils, and treated effluent for the purposes of
determining:
"(1) the nature and amounts of soluble (possible harmful)
mineral salts present, and
(2) the fertilizing or manurial values of the samples."
The data contained in these reports for fertilizer or nutrient
effects on soils and plants offer a point of historical comparison
with existing conditions.
In order to have a basis for comparison, the Corps team took
the 1972 soil and plant samples from sites as close as possible to
10
-------
the 1924 Avery-Anderson localities. The following relationship
describes the sample locations relative to each sampling, and is
keyed to the sample location map (Figure 1):
CORPS OF ENGINEERS AVERY-ANDERSON
MAP COORDINATE SAMPLES (1972) SAMPLES /1924'>
65W/90S 1 A
65W/91S 4 B
15E/110S 2 P
50E/39S 3 K
53E/161S 6 H
55E/39S 5 N
Sampling Procedure
The Corps' soil sampling procedure consisted of obtaining a
representative sample by augering at each of the six locations to
depths of 0-2.5, 2.5-18, and 25-45 cm. Also at sample location 5
a control sample was obtained from an area that had never been
irrigated with wastewater. Samples of several thousand grams each
were collected, split into duplicates by combining opposite quarters
after coning and quartering, and one-half of each was shipped to
D. J. David's laboratory in Australia and R. L. Jones' laboratory
in Illinois. These sample depths do not necessarily correspond to
pedologic horizons of the undisturbed soil profile. Rather they
reflect the best estimate of sewage, water penetration based on
knowledge of the soil's infiltration capacity and water conductivity
characteristics. Similarly, plant samples were collected at soil
11
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sample locations (except sites 1 and 4) in the form of clippings,
bagged, and sent to D. J. David's laboratory where they were prepared
for the various analyses by drying and grinding. Samples from sites 1
and 4 are missing because cattle had recently grazed the forage too
close to the soil surface to permit collection consistent with that at
the other sites.
Laboratory Procedure
The soil samples were air-dried and crushed to pass a 2-mm sieve.
For pH determination, soil was mixed with distilled water in a one to
one ratio by weight and equilibrated for one hour. For estimation of
concentrations of the elements in question that are available to plants,
20 g of each soil sample was extracted with 100 ml of 0.1 N HC1 by
shaking overnight (18 hours), centrifuged, and filtered through Whatman
No. 42 paper. The filtrate was analyzed by atomic absorption spectro-
scopy. For total analyses of the soils, 0.25 g of soil was digested in
a platinum crucible with hydrofluoric acid and eight drops of sulphuric
acid, the acid fumed off and the residue taken up in hydrochloric acid
and made up to a final voLume of 50 ml. Phosphorus was determined by
the vanadomolybdate method. An aliquot of this digestion or of one
prepared from 5 g of soil and made to a final volume of 25 ml for
traces, was used for the determination of total metallic elements by
atomic absorption spectroscopy. Carbon was determined by the chromic
acid oxidation method, N by the Kjeldahl method (5) and cation exchange
capacity by determination of ammonia after saturation at pH 7 and
13
-------
subsequent displacement from the exchange sites (9). Boron was
determined using the methylene blue-fluoroborate complex method '30)
in conjunction with HF-acid digestion of the soil minerals. Plant
samples were wet digested and made to appropriate final volumes for
the determination of major and minor elements.
14
-------
-------
DISCUSSION
In order to properly assess the information presented it is
first necessary to realize what is, and is not, known about the
historical operation of Board of Works Farm as it would affect the
analyses presented here. Probably the most important and obvious
unknown is the quality of wastewater that has been applied over
time. This is particularly important in relation to the heavy
metal analyses because of the influence of the secular growth of
technology and industrialization. For example, we suspect that Pb,
Cr, Cd, and Co levels in the sewage have been increasing especially
with the war-stimulated industrialization of Melbourne beginning in
the 1940"s. We have assumed that the quantities of sewage applied
to long existing paddocks has not varied substantially from year to
year.
Site Selection for Sample Collection
During the sampling phase of the investigation, an attempt was
made to collect samples from the center of the irrigation bays0
Each bay is approximately 7.6 m (25 ft) wide by 198 m (650 ft) long,
so the sampling location would be 92-107 m (300-350 ft) from the
outfall structure,, Flood-type irrigation introduces water at the
head of the field, allowing it to flow over and through the soil,
and removes the percolate by seepage into a collection ditch at the
down-slope end of the field. Because the wastewater and especially
15
-------
its solid component is not uniformly spread over the entire field,
concentrations of certain constituents will be greatest near the
outfall. We do not know the hydraulics of this situation and there-
fore can not estimate constituent loadings at the various locations.
An example of this phenomenon is location Number 3 (Figure 1). The
1924 Avery-Anderson reports (2) referred to this sample as
"primarily sewage solids", suggesting that the investigators at the
time thought that the sample resembled sewage sludge (indicating a
large accumulation of solids and organic matter). In fact, the
sampling site was located only 3.66 m (4 yd) from the sewage outfall
to the field. This lends some validity to the statement that certain
constituents will be greatest near the outfal!0 In any case, sample
locations were ranked according to length of time in service
Soil Composition
It can generally be stated that if an element is present in
greater amounts in the surface horizons than in the subsoil, then
this indicates that it is used by vascular plants, transferred to
aerial portions of the plant, and held by soil colloids and organic
matter against leaching (19). This is certainly true of the macro-
nutrients N, P, Ca and perhaps Mg as shown in Table 3. Soil content
of K increases with depth in both the control and treated plots and
may be the result of marine water influence on the sediments. This
explanation is suggested by the low Ca/Mg ratios and the fairly
monotonous distribution of B concentration levels with soil depth.
16
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17
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Table 4. Comparison of N and P content in soils for the years 1924
and 1972. "Sewage Solids" was the description given to the
soil sample taken at the Werribee Farm in 1924. The Avery-
Anderson Report (2) stated that the sample location was about
3.66 m (4 yd) off the sewage outfall and within 7.6 cm (3 in)
of the surface. Sample number refers to sites located by
number in Fig. 1. Data for 1972 come from Table 3 of this
paper.,
N
Sample
Site Number 1924
Years
Control , .
Sample - O.U(a)
48 1 n.d.
58 4 0.13
60 2 n.d.
60 6 0.24
73 5 0.36
73 3 2.16
("Sewage
Solids")
P
1972 1924 1972
0.46 0.013(b) 0.053
0.65 n.d 0.154
0.88 0.026 0.135
0.89 n.d. 0.157
1.57 0.044 0.201
1.56 0.052 0.213
1.84 0.29 0.315
(a) Range 0.13 - 0.14
(b) Range 0.01 - 0.026
(-^Estimated from sample location description in 1924 Avery-Anderson
Report with 1972 as reference.
18
-------
Comparing the concentration levels of total K, Ca, and Mg presented
in Table 3 with the range of levels as given in Table 6 for normal
soils, it is noteworthy for future discussion purposes that the
Werribee Farm soils have intermediate K and low Ca and Mg contents.
Generally, irrigation with wastewater has increased N and P
concentrations of the soil compared to those values reported here for
the control plots and those reported in 1924 as shown in Table 4.
The concentration of N in the top soil appears to be considerably in
excess of the expected normal value found in soils (compare Tables
3 and 6). This suggests that there has been a build-up of organic
N in the surface layer over time, while subsoil concentrations
have remained rather constant as would be expected.
Phosphorus concentrations in the surface layer fall within the
expected normal range for top soil (compare Tables 3 and 6). Khin
and Leeper (18) reported that soil total P increased from 513 ppm to
3730 ppm for unirrigated and irrigated samples, respectively. Their
work showed that a large percentage of the total P was organic P
(35%) with most of the remainder associated with calcium, iron, and
aluminum compounds (30, 19, and 107», respectively). These data
indicate a sevenfold increase in total P, whereas, the present study
shows four-fold increase in total P of irrigated versus non-irrigated
samples (compare control and sample 5). The Avery-Anderson Report
(2) indicated values for total P in the range reported by Khin and
Leeper and this study for non-irrigated samples. Table 8 shows
19
-------
approximately a two-fold increase in. plant uptake of P for irrigated
versus non-irrigated samples.,
The C content of the irrigated surface soil has increased
markedly over that in the surface horizon of the control sample, with
insignificant change in the subsoil. Khin and Leeper (18) reported
a similar increase in organic C from 3.7% for unirrigated soils
to 10.0% for irrigated soils.. Wastewater irrigation and current
farming practices have lowered the C/N ratio of the surface soil from
about 13/1 to an average of about 10/1. This indicates that there
has been a substantial accumulation of nitrogenous organic matter
over time.
Cation exchange capacity is closely related to organic C
content, increasing by 1.4 me/% C. This relationship is derived from
the simple linear correlation of cation exchange capacity with C
that yielded the equation
Y = 14.67 + 1.40X,
where Y is exchange capacity and X is percent C. The correla-
tion coefficient (r) = 0.91. Cation exchange capacity of organic
matter in these soils, on the basis of this relationship, is 81.4
me/100 g a value consistent with figures often cited for soils.
Soil pH is an important property in determining heavy metal
trace element availability for either plant uptake or leaching.
Khin and Leeper (18) reported that soil pH at the Board of Works
Farm decreased from 7.5 to 6.2 for unirrigated versus irrigated areas.
The pH of the soils sampled in this study are quite variable ranging
20
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from strongly acid (pH 5.1) to moderately alkaline (pH 8.4). In
comparison with the acid control site, the irrigated pastures
appear to have a higher pH. Heavy metals become more available as
pH approaches a value in the lower range of 5 to 6.
From the data presented in Table 5, applications of sewage do
not consistantly affect the distribution of total or extractable Mn
in the soil profile. Apparently very little of the Mn applied as
a constituent of sewage is retained in the soil profile to the depths
sampled. Nevertheless, Mn and Fe are relatively unimportant addi-
tions in sewage to soils because they are naturally present in soils
at relatively high amounts and are already managed or cropped so as
not to present a problem to forage production (19). The total soil
concentration levels presented for Mn in Table 5 are generally within
the range reported in the literature (Table 6) for agricultural soils.
'All of the total soil concentration levels are at the low end of the
range and in fact are several hundred ppm below the "typical" values
reported. Whether or not an actual Mn deficiency exists is not
discernible from the data or visual observations of the grass plants.
Furthermore, a Mn deficiency is not indicated by the extractable soil
Mn content which, unlike total soil amounts, far exceeds or is in the
upper range of values reported for agricultural soils
Chromium, like Mn, is added in small amounts compared to native
levels and, with the exception of the 60-year treated plot (No. 6),
displays only small variation with depth among plots. For the most
23
-------
part, extractable amounts of Cr are within the concentration levels
expected in normal agricultural soils (Table 6)
Except for sample 3, the total concentration levels for Pb presented
in Table 5 appear to be within the range of values reported for agricul-
tural soils (Table 6). On the other hand, the total soil concentration
levels of Pb are much greater than reported "typical" values for agri-
cultural soils including that from the control site. In all
cases upper layers of sewage irrigated pastures contain greater total
concentration levels than are found in the surface of the unirrigated
area sampled as a control. In the subsoil all Pb concentration levels
approach a common, low value which is consistent with the knowledge that
very little Pb migrates to lower soil depths with percolating water.
However, it was found in only two instances (Numbers 6 and 3) that
extractable lead concentration levels in the soil surface had been
increased above non-irrigated control levels by sewage irrigation, and
in these two instances the extractable lead content exceeds levels
reported for normal agricultural soils (Table 6). Because Pb is bound
so tightly in surface soil, it is a good index by which to determine
how well the analytical results from the soil samples actually reflect
the length of time the area has been irrigated with sewage. By using
Pb as an index to measure the adequacy of the soil sampling method, the
greatest correspondence between total Pb concentration levels in soils
and the length of time that the particular area has been irrigated with
sewage is found in sample numbers 4, 6, and 3; the order or arrangement
in which they are presented in Table 5. The use of Pb values
24
-------
as an index of the actual amounts of sewage applied seems to be
corroborated and warranted by the total C contents and the cation
exchange capacity values determined for samples 4, 6, and 3. Thus, in
the following discussion concerning the distribution of trace elements
as affected by sewage irrigation of pasture lands, a greater emphasis
will be placed on comparisons between the analytical results from these
three sampling sites in relation to those data from samples representing
the non-irrigated pasture.
Under conditions of neutral or alkaline reaction or little soil
profile development there is scant change in trace element content with
depth (e.g., 14, 28, 31). However, acetic acid extractable trace ele-
ment contents of soils, especially for well drained podzolic soils
where percolation of organic acids is important to development, normally
decrease with depth in the soil profile. This phenomenon reflects major
shifts in form or in the nature of the compounds in which the trace ele-
ments are bound.
Referring to the Zn data in Table 5, it can be seen that in the
control sample total concentration levels are faily uniform with depth,
representing a rather "typical" soil content, but extractable Zn concen-
tration levels decrease with soil depth. In view of what has been re-
ported by others with regard to proportions of total and extractable Zn
contents, the non-irrigated Werribee Farm soil is typical. Where long-
term sewage irrigation has been practiced both total and extractable Zn
contents of soils have been substantially increased over those found for
non-irrigated plots. Nevertheless, only samples from sites irrigated
25
-------
for 60 (site 6) and 73 (site 3) years have total Zn contents in the
soil surface layer that are much above Zn contents expected in normal
soils. It is apparent from these data that much of the Zn applied
as a constituent of sewage has migrated to deeper zones in the soil
profile and remains in an extractable form. The extractable Zn
contents in the surface layer of all the irrigated sites are above
the range of concentration levels in normal soils. Even at the deep-
est soil sampling depth, the portion of the total Zn content that is
attributable to sewage irrigations is much more soluble when compared
to that in native Zn compounds of the soil.
Recently, Jones, et. al» (16) reported increased uptake of Cd by
soybean plants grown on sludge-amended soils. Since increased absorp-
tion of Cd by corn plants fertilized with digested sewage sludge had
been reported earlier by the same authors (15) many life scientists
have become greatly concerned with regard to the potential health
hazard of this element to animal and man as municipal wastes are
recycled to crop land. Because of the protective action provided by
Zn, Fe, Cu, and Se for both plants and animals against the adverse
effects of Cd, the toxic hazard is best assessed by considering Cd
content in relation to contents of these other trace, elements. There-
fore, it is important that we consider the relationship between the Zn
and Cd content in raw sewage of Melbourne and of these two elements
in Werribee Farm soils. First, it should be observed from Table 2
that the Cd content in the raw sewage from Melbourne is higher than
expected relative to the Zn content. The Zn to Cd ratio is only a
little greater than 14. In sharp contrast with this ratio, it can be
26
-------
seen in Table 5 that where soils have been irrigated with the sewage
for a long period of time the Zn to Cd ratio in the surface layer is
in the neighborhood of 100 or somewhat greater than would be expected
in normal soils. This relationship is even more important in view of
the fact that the unirrigated control sample has a Zn to Cd ratio of
about 47 One or a combination of several alternative hypotheses can
account for this relationship The most reasonable explanation is
that the sewage samples collected for Cd analyses did not represent
average conditions for concentration levels of the element. If the
sewage samples taken in 1970 and 1971 are representative for Cd
contents, then the concentration levels may have been recently increased
by some metal processing waste being discharged into the sewers and this
recent change has not yet drastically altered concentration levels of the
element in irrigated soils. Alternatively, Cd can be leaching from the
soil at a faster rate than Zn, thus widening the ratio. Support is
given to this proposition by the decline in ratio size for both total
and extractable forms with depth which implies a fast downward movement
of Cd relative to Zn.
By comparing the data given for total soil Cu contents in Table 5
with those for normal soils in Table 6, several facts are apparent.
For one thing, the non-irrigated soils have total and extractable Cu
contents that are within the low end of the ranges as reported for
normal soils» Furthermore, the total Cu contents of soils which have
been irrigated with sewage for 48 to 73 years are still within the
range of values for normal soils, even though concentration levels
have been much increased in the soil surfaces and to a lesser extent
27
-------
in the subsoils. In only two instances (sites 6 and 3) do
extractable Cu contents of irrigated soils exceed that expected
from normal agricultural soils. In these two instances extractable
Cu contents in the 2.5 to 18 cm depth are slightly greater than
7 ppm as compared to a typical value of 2 ppm in agricultural soils.
The total Ni contents for all the soils are within the range of
values expected in normal agricultural soils. Unlike several of the
other trace elements applied on land as a constituent of sewage, Ni
does not appear to accumulate near the surface of the soil. Whatever
increases in total Ni contents that have occurred in soils as a result
of sewage irrigation reflect that Ni appears mobile and has been
fairly uniformly distributed throughout the soil profile. Extractable
Ni contents of soils suggest that a substantial amount of that added
either remains or becomes extractable by acid. All surface-soil
samples from areas irrigated with sewage for 60 or more years have
extractable Ni contents that range from 10 to 32 ppm which are higher
than the range of values expected for normal soils. These levels
are also a substantial proportion of the total. This increase in
extractable Ni content of soils irrigated with sewage over that
determined for non-irrigated controls appears to be closely associated
with the thin soil layer having a relatively high organic matter
content.
In the proceedings of a conference held in Champaign, Illinois
in 1973 to consider the recycling of municipal sludges and wastewater
to land, it was recommended by Chaney (8) that "Toxic metal additions
28
-------
to agricultural soils should not exceed Zn (equivalent) levels equal
to five percent of the C.E.C. of the unamended soil (at pH 6.5 for
sensitive crops)". The Zn equivalent referred to is that set forth
by Chumbley (10) in which he states that:
"Advisory experience and the results of pot experiments
suggest that copper is twice as toxic as the same amount
of zinc and that nickel is 8 times as toxic as the same
amount of zinc. Following from this the amount of toxic
metal can be expressed as a single figure in parts per
million by adding together the zinc content, twice the
copper content and 8 times the nickel content and it is
reasonable to call this the 'zinc equivalent' of the
sewage."
Calculations for "zinc equivalent" relevant to cation exchange
capacity are given in Table 7. The "zinc equivalent" has exceeded
five percent of the exchange capacity on the pasture represented by
sample 6 and sample 3 is very near five percent. These values are
conservative because they were calculated on the basis of cation
exchange capacity as determined for the respective soil sample.
Whereas, according to Chancy's recommendation the cation exchange
capacity of the sample collected from the unamended or non-irrigated
area should have been used, in which case 8.25 and 8.57 percent of the
C.E.C. for the surface-soil samples numbered 6 and 3, respectively,
are satisfied by the "zinc equivalent". The reader may recall that
the pH values are 4.9 and 5.2 for surface-soil samples numbers 6 and
3 (Table 5) and thus, are considerably below the recommended minimum
pH value of 6.5 as suggested for the critical "zinc equivalent".
These acid conditions favor absorption of trace elements by plants.
However, at the time of soil and forage sampling, no symptoms of
29
-------
toxicity were apparent. No effort was made to make yield determina-
tions and it is in yield reduction that excesses of toxic elements
are first recognized before overt signs of morbidity are apparent.
Plant Composition
In the following discussion of the chemical composition data
presented in Table 8, it should be kept in mind that the quantities
of trace elements in pasture grasses and legumes vary with species
composition, characteristics of the growing season, and stage of
growth. Thus, the amount of speculation about the toxicological
effects that the concentration levels of the several chemical elements
might present to grazing animals is very limited because the data in
Table 8 were obtained from only one sampling period.
It was not practical to take plant tissue samples at sites repre-
sented by soil sample numbers 1 and 4. The foliage was too short to
collect without contaminating the green forage samples with soil. In
accordance with the grazing rotation practiced, the cattle had just
been removed from the two sites in anticipation of the next irriga-
tion with sewage.
Comparing the chemical composition of the several Werribee Farm
samples (Table 8) with the range in chemical composition of common
range grasses and legumes as presented in Table 9 provides some
insight into the changes in mineral contents of forages growing on
soils irrigated with sewage for long periods of time. First, it is
evident from the N content of forage samples from irrigated
30
-------
Table 7. Extractable Zn, Cu and Ni contents of surface-soil horizons
expressed as a percentage of the cation exchange capacity,
Cu has been adjusted by multiplying that extracted by
0.1 N_ HC1 by two and Ni by multiplying the acid extractable
content by eight. These conventions conform to those of
Chumbley (10) for the calculation of the "zinc equivalent".
Sample
Number Depth
cm
Control 0-2.5
2.5
4 0
2.5
6 0
2.5
3 0
2.5
- 18
- 2.5
- 18
- 2.5
- 18
- 2.5
- 18
C.E.C.
me/lOOg
22.5
15.7
30.3
17.3
32.2
25.3
41.1
20.3
Zn
0.22
0.04
1.28
0.64
4.16
2.24
2.53
1.57
Cu
0.03
0.03
0.01
0.08
0.09
0.18
0.04
0.23
Ni
7 _ _ _ .
0.23
0.17
0.25
0.20
1.52
0.99
2.12
0.86
Sum
0.48
0.24
1.54
0.92
5o77
3.41
4.69
2.66
31
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Table 9. Range of chemical composition of common range grasses
and legumes (15,19,21), dry weight basis of green
roughages. No implication is intended that the mean
is equal to the median value within each range.
ELEMENT
N 7o
P 7o
K 7o
Ca 7»
Mg 7»
Na 7o
Mo ppm
Cu ppm
Ni ppm
Zn ppm
Cd ppm
Pb ppm
Mn ppm
Cr ppm
Co ppm
B ppm
Fe ppm
RANGE
2.55
0.19
1.16
0.62
0.15
0.30
0.1
2.0
0.1
8.0
0.2
0.1
15.0
0.1
0.05
1.0
250.0
- 4.06
- 0.45
-2.76
- 0.90
- 0.35
- 0.45
- 4.0
- 15.0
- 3.5
- 60.0
- 0.8
- 10.0
- 200.0
- 0.5
- 0.5
- 80.0
- 600.0
33
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and non-irrigated plots that long-term application of sewage has
resulted in significant increases of this element. Nitrogen concen-
tration levels in the plant tissues from the control site are below,
whereas those from irrigated pastures are within, the range of values
expected in a mixture of grasses and legumes. Also, the plant
tissues collected from the non-irrigated site have P contents within
the expected range of values, but those from irrigated sites have
concentration levels much above the normal range of values. Relatively
speaking, the K contents of irrigated plants have not been increased
over those from the control site to the same extent as the increases
in N and P. In comparison to typical contents, the K
concentration level in the foliage from the control site is about
what would be expected. Sewage irrigations have caused K concentra-
tion levels to be increased in plant tissues but the percent increase
is less than for N and P. In spite of the relatively high uptake by
plants growing on the control plots, K concentration levels were
increased in every instance by sewage irrigation and, except for grass
samples collected at site number 3, all have K contents above the range
of values for common pasture grasses. In sharp contrast to N, P, and
K, the contents of Ca and Mg in plant tissues have not been increased
by sewage irrigation. In fact, there appears to have been little if
any change in Ca and Mg content as a result of sewage irrigations.
At the same time, Ca contents appear to be lower than that of common
range grasses, whereas Mg contents are within the expected range of
34
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values. Considering all of the elements absorbed in large quantities
by plants, the Na content of plants appear to have been increased to
the greatest extent by sewage irrigation. In all the areas irrigated
with sewage the plants growing there contain 2 to 3 times more Na than
those growing on the non-irrigated area. It is significant that the
Na content was increased from a value just below that expected in
common range grasses and legumes to contents much above the expected
range of values with sewage irrigation,, Although we don't know how to
assess the increased Na contents resulting from sewage irrigation as
it affects the health of cattle and sheep consuming the forage, it
seems appropriate to discuss the increased contents of K in forages
with irrigation and the lack of change in Ca and Mg contents in
regards to animal health.
A morbid condition often called grass tetany or staggers, and more
appropriately known as hypomagnesia by animal scientists and veteri-
narians has been observed in cattle and sheep at various locations
throughout the world. It is characterized by convulsions and paralysis
in animals having lowMg concentration levels in blood serum.
The disease was recognized in beef cattle many years ago by the veteri-
narian serving the Werribee Farm and is now avoided by adding MgO to
the dry hay fed to the animals. This disease is not only endemic to
Werribee Farm, but rather is also widespread in Australia and especially
on areas with similar deltaic soil types.
Grass tetany occurs when Mg is available in amounts which
are inadequate to meet metabolic demands. It is not a true deficiency
35
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°f Mg in that it is conditioned by a number of factors such as
the .K, crude protein, and organic acid contents of forages.
In turn the forage contents of these three substances are influenced
to a large degree by N and K. fertilization, environmental
temperatures, and the availability of soil moisture. All of these
factors have been discussed in some detail by Cline (11). In 1957,
Kemp and 't Hart (17) reported that a significant correlation existed
between the number of grass tetany cases in cattle and the ratio of
K/Ca + Mg, calculated as the milliequivalents per kilogram of each
element in forage samples. When the value of the K/Ca + Mg ratio was
less than 2.2 they found very few grass tetany cases but when the ratio
was above this critical value they found 6.66 percent of 1908 head of
cattle in their study suffered the disease. They also present evidence
that as the K/Ca + Mg ratio increases in the pasture forages above the
critical 2.2 value, incidence of the disease increases. When the ratio
lies between 3.01 to 3.40, 15 to 20 percent of the animals may contract
the disease.
Because large quantities of K are supplied to the Werribee Farm
soils by sewage irrigation and under a grazing system very little K is
removed, it is of some importance to know how the K/Ca + Mg ratio have
been affected. Not more than 10 to 20 percent of the three elements
involved in the ratio would be removed from the irrigated areas as
body constituents of the beef cattle and sheep taken for slaughter.
Therefore, the major portion of these three elements, supplied in the
sewage, remains on or in the soil unless removed in the drainage water.
36
-------
In Table 10 it can be seen that the K/Ca + Mg ratio values as
determined for the Werribee Farm forage plants are below the critical
value of 2.2 only in the samples from the non-irrigated area and in
sample 3 collected from an area which has been irrigated with sewage
for 73 years. Forage samples from all the other irrigated sites have
K/Ca + Mg ratio values that exceed the critical value and thus indicate
a potential grass tetany problem when sewage is used to irrigate
pastures on soils having low Mg contents. A strong inverse relation-
ship exists between the K/Ca + Mg values in forages and similar ratio
values calculated from the total contents of the three elements in soils.
The simple linear correlation of plant ratio (Y) with that in soil (X)
gives Y = 3.24 - 0.834X with r = -0.865 (r * 0.878 at P = 0.05). In
view of the data presented in Table 3, it appears that small decreases
of K and increases of Ca and Mg contents in soils have occurred as a
result of sewage irrigation. These results are indeed surprising and
are all the more impressive because they have been observed from the
collection of such a few samples. It is regretable that K was not
included in the analyses of water in the drains.
In view of the decreased soil contents it appears inconsistent for
the K content of the forage samples to have been increased by sewage
irrigations. Furthermore, N is reported by Schutte (25) and Emmert
(13) to be antagonistic to the absorption of K by plants while at the
same time stimulating uptake of Mg. However, the correlations between
K/Ca + Mg ratio values and N contents in forage samples from Werribee
Farm do not reflect these kinds of interactions. A positive correlation
37
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Table 10. Ratios of K/Ca + Mg (calculated as me/kg) in forages
and soils and N contents in forages. Content of N
is included from Table 8 for comparison.
K
Site Sample Ca + Mg % N in
Years Old Number Forage
Control - 1.37 2,34 1.80
60 2 2,42 1.13 4.01
60 6 2.24 0.84 3.44
73 5 2.99 0.7') 3.85
73 3 1.87 1028 3.73
38
-------
between the K/CA + Mg ratio values and N content, yielding
Y = 0.53 4- 0.40X with r = 0.782 (r * 0.805 at P = 0.10) is almost
significant. Therefore, the interaction effects between N, K, and
Mg appear contrary to what is generally reported for plants. More
thorough study of pastures on the Farm may establish this relation-
ship more firmly. On the other hand, Zn, Cu, Mn, and B stimulate the
uptake of K and their influence apparently is the dominant or con-
trolling factor in the sewage irrigated vegetation.
Among the results of analyses of forage samples for 15 chemical
elements (Table 8), Mn concentration levels are the only ones which
appear with any degree of certainty to have been decreased by sewage
irrigation. But even though Mn contents have been decreased they are
still within the range of values expected in common range grasses and
legumes. In general, Mn absorption by plants is enhanced by K and
depressed by Ca and Cu. Thus, it appears that even though Mn absorption
has been decreased by sewage irrigation the overall effect is one of
stabilizing the uptake at an adequate level in plant tissues.
Zinc contents of forage samples reflect the sewage irrigations to
the greatest extent in only those samples from the two sites numbered
6 and 3. It may be recalled that by the use of Pb as an index, it is
these two sites which we estimate have received the greatest loading
rates of sewage during the history of the Farm. At these sites Zn
contents of the vegetation are more than twice the highest values
expected in common range grasses and legumes. The fact that Ca and P
are antagonistic to Zn uptake by plants may account for the high but
39
-------
reasonable levels of Zn in foliage tissues. Since the Ca content is
low, P is probably the element which exerts the major control over Zn
absorption and translocation to aerial tissues.
From the comparison of Cu contents of the green forage samples
from the non-irrigated control site to that contained in all of the
samples from irrigated areas, it is obvious that this metal has been
much increased in the vegetation (Table 8). Nevertheless, only in the
sample from irrigated site 6 does the vegetation contain Cu contents
in excess of that which has been reported as normal values (Table 9).
Like Zn, the Cu content of the vegetation is probably maintained at
a tolerable level by the plant available P supplied as a constituent
of the sewage and accumulated in the soils. Unusually high levels of
available soil P are known to be antagonistic in the uptake of Cu by
plants.
All of the forage samples collected from sewage-irrigated sites,
except sample 5, have Cd contents that barely exceed levels expected
in common range grasses and legumes. It may be recalled that the
increasing Zn to Cd ratios of extractable contents in soils with
increasing loading rates of sewage were discussed above and it is of
some interest to note a similar trend for the ratio values in the
vegetation. In every case the Zn to Cd ratio values are greater in
forage samples representative of irrigated sites than the ratio value
of 65 determined for the sample from the non-irrigated control plot.
It is especially noteworthy that for samples numbered 6 and 3, (sites
that have had the greatest amount of sewage applied according to the
40
-------
use of the soil contents of Pb as an index) the Zn to Cd ratio values
are 117 and 160, respectively.
In view of the reasonable extractable concentration levels in
the soils, the exceedingly high Cr contents in forage samples from
both irrigated and non-irrigated sites on the Werribee Farm can not be
explained. From a review of the literature for reported Cr contents
found in a number of plant tissues, including pasture grasses,
Underwood (29) found 0.1 to 0.5 ppm to be the expected range of con-
centration levels and these are the values included here in Table 9.
The Cr concentration levels reported here for forage samples are
presented with reservations until additional samples can be collected
and analyzed. Because Cr is so poorly absorbed by animals and has
such a low order of toxicity, even if concentration levels in Table 8
are correct values they would not be considered to be a health hazard
to sheep and cattle.
Even though it can not be said with any degree of certainty from
the data in Table 8 that sewage irrigations have increased the extract-
able Co content of soils, it appears that concentration levels are
enhanced in the forage. Although three of the forage samples from
Sewage irrigated pastures contain Co contents that exceed values
reported for common range grasses and legumes, the concentration levels
do not seem excessive from the standpoint of animal health. Like Cr,
Co has a fairly low order of toxicity in animals (29).
As discussed above, irrigation of pastures has substantially
increased total and extractable Pb contents of some of the soils and
41
-------
thus it is somewhat surprising that the Pb content of the forage grown
on the pastures is not considerably higher than that found in the
forage sample from the non-irrigated control site. None of the forage
samples contained Pb in concentration levels equal to the higher
values expected in common range grasses and legumes.
Although three of the forage samples from sewage-irrigated sites
have Ni contents that exceed the highest values expected in normal
pasture vegetation, no adverse symptoms of high Ni levels were apparent.
With regard to untoward effects in animals, Ni is like Cr in that it is
poorly absorbed from ordinary diets and is relatively nontoxic (29).
It appears rather unlikely that the Ni contents of any of the forages
grown on the Werribee Farm pastures represent a Ni-related health
problem to animals.
As can be seen in Table 8, the Fe contents of forage samples are
highly variable. The Fe content of the forage sample from the control
or non-irrigated site is much higher than that expected for normal
pasture vegetation. Except in the forage sample from site 6, sewage
irrigation appears to have decreased the uptake of Fe by plants. But
all of the forage samples have Fe concentration levels equal to or
greater than would be expected as an average value. The fact that the
greatest Fe content occurs in the sample from irrigated site 6 is of
special interest, because this sample also contains the highest con-
centration levels of Ca, Zn, Cu, Cd, Cr, and Ni. Except for Cr, all
of these chemical elements and Mn are known to be antagonistic to the
absorption and/or translocatiori of Fe into plant foliage. On the other
42
-------
hand, K stimulates the uptake of Fe by plants and therefore may be
the off-setting or protective factor against an Fe deficiency (25).
Water Composition
For a description of the surface drainage system, the reader is
referred to the article entitled "Waste into Wealth" which appeared
in the 1972 Fall issue of Water Spectrum (26). In the following brief
discussion of the chemical content of the drainage water from the
Werribee Farm, it should be kept in mind that the objectives of the
Melbourne Board of Works staff at the time the farm was established
in 1893 was to use this system to reduce the suspended solids to less
than 30 ppm and the biochemical oxygen demand to less than 20 ppm
prior to discharging the wastewater to Port Phillip Bay. To this end,
the Farm has been successful, even though the raw sewage waste loads
soon exceeded the designed capacity of the Farm after its establish-
ment. Thus, this farm was never selected nor was the system designed
to treat raw sewage to the level of "no discharge of critical pollu-
tants" which will be the United States' goal in designing future land
treatment systems to achieve tertiary treatment of and nutrient
removal from wastewaters.
If we assume a hydrologic equilibrium, that one volume of water
added to the paddocks is represented by one volume in the drains,
then it can be inferred from the data in Table 11 that 88 percent of
the N and 91 percent of the P is being removed from the raw sewage.
If evapotranspiration losses (90.4 cm) are considered for this area
43
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where annual precipitation is about 50 cm, than N and P removals on a
mass basis are even higher. The averages of 5.9 ppm of total N and
and 2.9 ppm of total P in drainage waters are considerably lower values
than the 20 ppm and 10 ppm reported as typical values for N and P,
respectively, in secondary treated effluents (22). Although the N and
P concentration levels in the farm drainage water are several times
greater than the levels expected in Port Phillip Bay (assuming average
composition of seawater as shown in Table 11), it is nevertheless of
higher quality with respect to these two elements than could have been
achieved by a secondary wastewater treatment plant. It was mentioned
before that it is regretable that K concentration levels in sewage and
drainage waters were not determined for use in estimating the K mass
balance, but from the standpoint of the quality of water discharging
to Port Phillip Bay it is not an important parameter. Seawater
normally contains about 380 ppm of K and it seems highly improbable
that the farm drainage waters would contain higher conceitration
levels. And even if they did the values would have little relevance
to the pollution of Port Phillip Bay.
Of the six heavy metals whose concentration levels were determined
in drainage waters, Ni is removed to the least extent by the soil-plant
system (Table 11). In spite of the fact that the soil-plant complex
removes only about 20 percent of the total Ni contained in raw sewage,
it does not appear likely that secondary treatment would reduce the Ni
content to lower levels. An average value for Ni concentration levels
in secoadary effluents has been reported to be about 0.2 ppm (23). By
44
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either treatment method the Ni content in waters discharged to Port
Phillip Bay would continue to be greater than is normally found in
seawater.
Again, with respect to the contents of the six heavy metal species
determined La the drainage waters, only Gu is within the range of con-
centration levels expected in seawater. Furthermore, Cu concentration
levels in the Farm drainage water are about the same as levels expected
in municipal effluents having secondary treatment.
A comparison between the raw sewage contents of Zn, Cd, Cr, and
Pb with their concentration levels as determined in drainage water
(Table 11), indicates that the irrigated-pasture system is removing
78 to 91 percent of these chemical elements. These removal rates are
as great if not greater than can be achieved with a well managed
secondary treatment plant. However, the concentration levels of all
of these four metals are higher in drainage water than would be expected
in seawater. On the other hand, we do not have concentration levels
of the several chemical element species in drainage water from similar
basalt derived deltaic soils irrigated with waters other than that of
raw sewage. Thus, we don't know the contribution of native mineral
weathering to concentration levels in drainage water.
Because of odor problems if for no other reason, it does not seem
likely that sanitary district staffs in more densely populated areas
of the United States will consider the use of untreated sewage to
irrigate pastures and crop lands. On the other hand, a rapid increase
in the use of secondary treated effluents for irrigation can be
46
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expected as laws and regulations are enforced requiring tertiary treat-
ment of municipal effluents before discharge to streams. Already
treated effluents from many municipalities in arid and semiarid regions
are used to irrigate golf courses, parks and crops of various kinds.
Many of these operations provide the opportunity to determine the
efficiency with which soil-plant systems remove nutrients and trace
elements from the applied effluent. Such information would be more
relevant to future land treatment systems than that reported here.
The results reported here are from a system that has been stressed
with considerably higher concentration levels of macronutrients and
trace elements than would be applied where only secondary effluents
are used for irrigation over an equivalent period of time. But the
Werribee Farm analyses are valuable from the standpoint of illustrating
the tremendous capacity of the soil-plant complex to attenuate water
pollutants by precipitation, adsorption, absorption, and assimilation.
Furthermore, the results demonstrate the capacity of growing plants
to buffer the effects of abnormally high soil contents of essential
and non-essential chemical elements on animal health.
47
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-------
SUMMARY
From the results of this cursory investigation of the chemical
characteristics of sewage, soils, forage, and drainage waters from the
Werribee Farm, some of the more important observations are as follows:
1. The irrigation of pastures with raw sewage at an annual rate
of about 111.8 cm (44 in) per year for a period of 48 to 73
years has resulted in increased soil contents of N, organic
C, and P. As C increases, cation exchange capacity increases
1.4 me per percent C. Soil C/N ratios decrease with sewage
irrigation while Ca/Mg ratios increase indicating greater
accumulations of N and Ca relative to C and Mg, respectively.
Contrary to what was anticipated, soil K contents remain
unchanged or declined with sewage irrigation.
2. With some exceptions total soil contents of all trace elements
included in the soil analyses were increased by sewage irriga-
tion. However, increases for total contents of both Ni and
B were consistently less than anticipated in view of amounts
contained in sewage. In spite of small increases in total
Ni, extractable soil contents of Ni were increased to levels
considerably higher than in normal soils. In general trace
element contents extractable with 0.1N HC1 increased with
sewage irrigation, most notable of which was Zn. Contrary to
expectation, Zn to Cd ratios of both total and extractable
contents in soils were increased with sewage irrigation. From
48
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the calculation of the "Zn equivalent," as proposed by others
as a means for limiting municipal waste application on land,
it is evident that at two sites, loading rates have already
exceeded recommended amounts.
3. Sewage irrigation of pasture land has resulted in increased
or unchanged forage contents of all the chemical elements
determined, except Mn. This one element was decreased, but
not to the extent that it would be considered to be at a
deficiency level in grasses and legumes. Large increases in
forage contents of N, P, K, and Na have occurred as a result
of sewage irrigations. Calcium and Mg contents of forage
have not been changed by irrigation. Because of the increased
uptake of K by plants in the presence of little change in Ca
and Mg contents of forage, irrigation has increased the
probability of grass tetany in cattle and sheep. In at least
two of the forage samples from irrigated pastures, Zn, Cr,
and Ni contents were considerably greater than would be
expected in normal grasses and legumes. But the concentration
level of Cr was also higher in the forage sample from non-
irrigated control sites than expected. These three essential
elements for animals have a low degree of toxicity and thus
their concentration levels do not indicate harmful effects to
animal health. In terms of animal health there are no indica-
tions that forage from irrigated sites contain trace elements
in either excessive or deficient amounts.
49
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4. Results of this investigation suggest that drainage effluents
from the Farm contain considerably less N and P than is
generally found in secondary effluents from biological waste-
water treatment plants. Therefore it is concluded that the
Melbourne Board of Works sewage irrigation operation has
provided a greater degree of protection against the pollution
of Port Phillip Bay than could have been obtained by biological
secondary treatment. Concentration levels of several heavy
metals in the Farm drainage water are about the same as
expected in secondary-treated municipal waste waters. Except
for Cu, all of the elements included in the analyses of farm
drainage water occur in higher concentration levels than would
be expected in seawater.
5. Hopefully this cursory examination of a sewage farm has contrib-
uted information toward answering some of the more salient
questions about land disposal of raw sewage and will stimulate
a more comprehensive study of the Melbourne operation, the
objectives of which should be the establishment of the mass
balances of the macro- and microelements in this system and
the accurate description of the chemical and physical mechanisms
operating in the system. Data from sewage farms that have been
in operation for long periods of time are useful for predicting
the fate of many water pollutants, particularly where their
contents in untreated sewage results in application rates on
soils which are considerably greater than would occur on a
land treatment system utilizing secondary effluents.
50
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ACKNOWLEDGEMENTS
Sherwood Reed, U. S. Army Cold Regions Research and Engineering
Laboratory, and Dr. Rufus Chaney, Agricultural Research Service,
Beltsville, Maryland, reviewed and commented on this manuscript.
Of course, the content and conclusions remain the responsibility
of the authors. The authors wish to acknowledge the Board of Works
Farm for providing valuable water quality data, and W. T. Whitman,
Chief, Western Reports Management Branch, Planning Division, Civil
Works Directorate, U. S. Army Corps of Engineers, for assistance in
field sampling and data collection.
51
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REFERENCES
1. Allison, L. E. 1965. Organic Carbon. In Methods of Soil
Analysis. Part 2. Chemical and Microbiological Properties.
(C. A. Black, ed.), Amer. Soc. Agronomy, Madison, WI, p.
1367-1373.
2. Anderson, V. G. and Avery, D., December 1924. Advising Chemist
Report to Melbourne and Metropolitan Board of Works, Melbourne,
Australia , typescript report.
3. Berrow, M. L. and Webber, J. 1972. Trace Elements in Sewage
Sludges. J. Sci. Fd Agric. 23:93-100.
4. Bowen, H. J. M. 1966. Trace Elements in Biochemistry. Academic
Press, New York, 241 pp.
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