EPA-600/2-77-054
April 1977
Environmental Protection Technology Series
OF
SLUDGE DISPOSAL RECYCLING HISTORY
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-054
April 1977
COMPREHENSIVE SUMMARY OF SLUDGE DISPOSAL
RECYCLING HISTORY
by
John C. Baxter*
William J. Martin*
Burns R. Sabey**
William E. Hart**
David B. Cohen*
Carl F. Calkins*
*Metropolitan Denver Sewage Disposal District No. 1
Commerce City, Colorado 80022
**Colorado State University
Fort Collins, Colorado 80521
Contract No. 68-03-2064
Project Officer
James A. Ryan
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U. S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solu-
tion and it involves defining the problem, measuring its impact, and search-
ing for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems for the prevention, treatment, and
management of wastewater and solid and hazardous waste pollutant discharges
from municipal and community sources, for the preservation and treatment of
public drinking water supplies, and to minimize the adverse economic, social,
health, and aesthetic effects of pollution. This publication is one of the
products of that research; a most vital communications link between the
researcher and the user community.
This history of land utilization of wastewater sludge was conducted for
the Ultimate Disposal Section of the Wastewater Research Division to gain
insight into the ramifications of land application when used by a large
municipality, as well as to document the results of the Metropolitan Denver.
Sewage Disposal District No. 1 in their efforts to utilize this process.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
i i i
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Pile* 06 Ondutie.
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Colle.cte.d at ^t/ie cU,ght6ul 6aAA.et6 0(J tkn nightman,
And the. fi&tid t>&i QfL game., it iA cattle.,
it the. Aatiiifiied towing oft heavy fe^.ne;
At night it uxvw blood i.n you/i uex.R6,
it U health, it ti> joy, it
dicta*. Hugo, In Let MiAeAableA {1S62
iv
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ABSTRACT
Processing and ultimate disposal of wastewater sludge is one of the most
costly unit processes within any sewage treatment plant. Since 1969 the
Metropolitan Denver Sewage Disposal District No. 1 (Metro) has been ex-
amining methods of sludge disposal which are both economical and environ-
mentally sound. The original flash-dryer incinerator units installed at
Metro proved to be costly and environmentally unacceptable, therefore,
land application became a viable alternative to flash drying or inciner-
ation.
Since 1971 the only mode of sludge disposal used by Metro has been land
application. A number of different application procedures have been tried
over the intervening years. The development of methodology and problems
associated with each procedure are discussed in the text.
Continuous applications of sludge to the soil at the Lowry Bombing Range
since 1969 have raised the concentration of nutrients, metals, salts and
organic matter. The effects of these loading rates on the soil,
crops and environment are evaluated.
The effects of various sludge applications to soil on germination, emer-
gence, subseqeunt plant growth and heavy metals uptake are discussed. Im-
proved wheat yields were experienced with sludge application rates up to
50 metric tons per hectare. Low germination and emergence rates were found
when crops were planted immediately after sludge incorporation. Inhibition
of germination decreased with increasing soil sludge incubation periods or
when dried sludge was used, suggesting that salts or some volatile component
within the sludge was inhibiting germination. Sorghum sudangrass was most
inhibited by sludge additions, and was affected to some extent by all sludge
treatments. Corn was intermediate in tolerance, and wheat was the least af-
fected by sludge additions. There appeared to be no inhibition of germina-
tion and emergence of wheat and corn after an incubation period of one month.
Microbial counts showed that sludged plots had an appreciable increase in to-
tal aerobic, total coliform and fecal streptococci bacteria. Counts of fecal
coliform bacteria demonstrated that there were no appreciable differences be-
tween the sludged and control plots.
Experiments examining the possibility of air drying anaerobically digested
liquid sludge in shallow earthen drying basins demonstrated that water is
lost through soil percolation in addition to evaporation, and that about half
of the nitrogen (N) content of sludge is lost during the drying process. A
discussion of future research needs is also included in the text.
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CONTENTS
Foreword i i i
Abstract v
Figures viii
Tabl es i x
I. Introducti on 1
II. Initial Experiences in Sludge Handling and Disposal 3
III. Development of Land Application Technology 5
IV. Evaluation of Sludge Disposal at the Lowry Bombing Range 14
A) Type of Sludge 14
B) Soil Effects of Sludge Disposal at the Lowry Bombing Range... 16
V. Research and Development 23
A) Land Application of Metro Sewage Sludge at Watkins, Colorado. 24
1) Materials and Methods 24
2) Results and Discussion 28
3) Conclusions 42
B) The Effect of Metro Sludge on Germination and Plant Growth
of Three Crops in a Greenhouse Study 43
1) Materials and Methods 43
2) Results and Discussion 44
3) Conclusions 48
C) Sludge Air Drying Project 51
1) Materials and Methods 51
2) Results and Discussion 51
3) Conclusions 56
VI. Future Agricultural Research and Development Projects 57
VII. Appendix 70
VIII. Glossary 84
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FIGURES
NO.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Filter cake sludge being tail gated onto soil surface.
Location map of Lowry Bombing Range sludge recycle site.
Sludge being transferred to 10 cubic meter manure spreaders.
Transport vehicle dumping into sludge storage hopper.
Modified fertilizer spreader broadcasting sludge.
Mold board plow incorporating sludge.
Lowry Bombing Range sludge recycle site showing areas used
for soil monitoring; shaded areas represent fields to which
sludge has been applied.
Plot design layout with identification and loadings (dry
metric tons per hectare) of each plot.
1972 wheat yield on filter cake plots.
pH of soil profile with various rates of sewage sludge addi-
tions.
Electrical conductivity of soil with various rates of sewage
sludge application.
Organic matter content of soil with various rates of sewage
sludge additions.
N03-N of soil with various rates of sewage sludge additions.
Available P content of soil with various rates of sewage
sludge additions.
Available K content of soil with various rates of sewage
sludge additions.
DTPA extractable Zn content of soil with various rates of
sewage sludge additions.
DTPA extractable Fe content of soil with various rates of
sewage sludge additions.
DTPA extractable Cu content of soil with various rates of
sewage sludge additions.
DTPA extractable Mn content of soil with various rates of
sewage sludge additions.
PAGE
5
6
9
10
11
12
18
26
32
34
34
35
36
36
37
37
38
38
39
viii
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TABLES
NO. PAGE
1 Comparison of incinerator versus land application sludge 10
disposal costs
2 A comparison of chemical composition of ferric chloride 15
and lime treated vacuum filter cake with polymer conditioned
vacuum filter cake (1972-1975 data)
3 Concentrations of DTPA extractable Zn, Fe, Cu, Mn and pH from 17
sludge additions to surface soils (0-15.24 cm) at the Lowry
Bombing Range
4 Comparison of chemical constituents of soil samples taken at 19
Lowry in May 1974 and November 1974
5 Concentrations of N03-N, NHj-N, TKN, P, K and conductivity 20
from sludge additions to surface soils (0-15.24 cm) at the
Lowry Bombing Range +
6 Concentrations of NOs-N, Nfy-N and TKN from subsurface soils 21
(61 to 91 cm depth) at the Lowry Bombing Range
7 Total metal composition of soil and wheat from the Lowry 22
Bombing Range
8 Characteristics of the Truckton loamy sand used in the study 24
9 Typical analysis of anaerobically and aerobically digested 25
sewage sludge produced by the Metropolitan Denver Sewage
Disposal District No. 1
10 Germination and emergence counts on July 20, 1971 for three 29
rows, each 7.65 meters long
11 Wheat stand counts on October 15, 1971 for three rows, each 29
1.83 meters long
12 Yield and nitrogen content of sorghum sudangrass as affected 30
by sludge application rate
13 Effect of sewage sludge addition to Truckton loamy sand on 3]
winter wheat yields, 1972
14 Total elemental composition of wheat grain as influenced by 32
rate of Metro sewage sludge addition
15 8.1 hectare filter cake demonstration showing wheat yields in 33
kilograms dry matter per hectare
16 Bacterial counts of soil samples taken from fields (fallow 49
and sorghum sudangrass) treated with sewage sludge
17 Average values for infiltration rates on sludge treated soils 40
18 Significant variables found in modeling water applications of 42
1.27, 2.54, 5.08 and 10.16 centimeters
19 Rate of sludge applications to Truckton sandy loam soil 43
20 Soil incubation periods and corresponding planting, thinning 44
and harvest data
ix
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M PAGE
21 a The effect of sewage sludge on germination and emergence 45
of seeds of three crops. Seeds planted one month after
the treatments were mixed with soil
21b Seeds planted three months after the treatments were mixed 46
with soil
21c Seeds planted six months after the treatments were mixed 47
with soil
22 The effect of sewage sludge on early growth (two weeks after 49
planting) of three crops grown in a greenhouse
23 The effect of sewage sludge on oven dry weight of three crops 50
grown in a greenhouse for 2 to 3 months
24 Initial depth of liquid sludge 52
25 Change in percent total solids content of drying basin with 52
ti me
26 Net evaporation required (centimeters per year) at various 54
sludge loading rates
27a Nitrogen concentration of 3 layers of liquid sludge in drying 55
basins
27b Nitrogen concentration as a percent of the total solids con- 55
centration of the three stratified samples
28 Range in various chemical constituents of liquid sludge con- 56
tained in drying basins
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INTRODUCTION
Sludge handling and disposal are the most problematic and costly unit pro-
cesses in wastewater treatment, particularly for large municipal wastewater
treatment facilities. At the Metropolitan Denver Sewage Disposal District
No. 1 (Metro) the cost of sludge disposal has been continuously increasing.
During 1974, sludge handling and disposal accounted for over one-half of the
total annual operation and maintenance budget.
Ultimate disposal of residues removed by the treatment process must enter
the ecosystem via one or more of three alternate pathways, land, atmosphere
or water. Since the Metro plant went on-line in 1966, three alternate sludge
disposal pathways have been utilized, each with particular advantages and dis-
advantages. The water pathway for sludge disposal is particularly inappropri-
ate in a semi-arid climate such as eastern Colorado where water resources are
seriously limited and must be protected. Inadvertent air pollution by incin-
eration or other means is rapidly becoming socially unacceptable. This is
particularly so in Denver where altitude and topography combine to make air
pollution entrapment during temperature inversions a serious concern. Having
ruled out the air and water pathways by trial and error, the only remaining
alternative for Metro was the application of sewage sludge residues to land.
One possible method of land application involves sanitary landfill ing or
burial of ash obtained from incineration of sewage sludge. While incinera-
tion provides a relatively inert residue which can be disposed of on land,
this method has certain drawbacks. In addition to air pollution, incinera-
tion destroys a potential resource. The increasing awareness of the finite
limitations of natural resource development has led to a search for new uses
for what have previously been considered wastes. Sewage sludge is a major
untapped resource which contains significant concentrations of nitrogen,
phosphorous, micronutrients, and humic materials. While this fact has been
known for years, the relatively low cost of synthetic commercial fertilizer
and soil amendment materials inhibited the farming community from exploit-
ing sewage sludge for growing crops. Recent economic developments, partic-
ularly the diminishing availability of energy and its fertilizer by-products
have created a new climate of greater acceptance for the beneficial recycling
of sewage sludge to land. However, this alternative also poses potential
problems such as heavy metals buildup in soils and plants, pathogen dissemi-
nation, and nitrate pollution of ground water. These problems can be over-
come by judicious loading rates, cropping, and environmental monitoring.
The Metro District is not unique in having to cope with these problems. The
authors of this report hope that other agencies charged with handling of sew-
age residues can benefit from Metro's experience in pursuit of a solution
for economically and ecologically recycling sewage sludge.
1
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The first four sections of this report summarize Metro's sludge handling
and disposal history from 1966 to the present time. The fifth and sixth
sections describe the research and development efforts to solve existing
problems as well as to anticipate future problems. The seventh and final
part attempts to summarize the operational and research experience with
recommendations for future efforts.
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INITIAL EXPERIENCES IN SLUDGE HANDLING AND DISPOSAL
The Metro plant was designed to treat 117 MGD (million gallons per day) of
wastewater. The residues removed in the process were to be dewatered through
dissolved air flotation and vacuum filtration, and ultimately disposed of by
flash drying and/or incineration. The anticipated ratios of raw primary, an-
aerobically digested primary and undigested waste activated sludge which com-
prised the vacuum filter feed sludge were expected to yield a filter cake mois-
ture content of no greater than 78%. The chemicals required for sludge condi-
tioning prior to vacuum filtration were expected to average 5% FeCls (ferric
chloride) and 10% lime. If these design conditions had been realized, the
amount of water requiring evaporation at full plant capacity would have equaled
311.2 metric tons per day. The design engineers provided three FDI (flash-dry-
er incinerator) units each having a maximum evaporative capacity of 5.9 metric
tons water per hour. All three units operating at 100% of the designed capa-
city would have provided a total evaporative capacity of 425 metric tons of
water per day.
Early in 1967 it became apparent that the ratio of waste activated sludge to
the total sludge mixture was much greater than originally anticipated by the
design engineer. The higher quantity of more difficult to dewater waste acti-
vated sludge had an adverse effect on the vacuum filter cake solids concentra-
tion, which averaged 14% to 18% TS (total solids) instead of the expected 22%
to 25%. This adverse sludge ratio increased the original design estimate for
chemicals required for vacuum filtration by more than 100%. This sequence of
events led to a serious overload condition of the evaporative capacity of the
FDI units. Mechanical problems and breakdowns as a result of the overload con-
dition were exacerbated by FeCl3 (ferric chloride) induced corrosion failures
of the stainless steel components of the FDI units.
By the fall of 1968 the sludge handling and disposal problem had reached
crisis proportions. As a result of mechanical problems, less than half of the
evaporative capacity of the FDI units was available for sludge disposal. Acti-
vated sludge accumulation in the biological treatment system caused a rapid
deterioration of final effluent quality. In order to avoid scouring of acti-
vated sludge from the secondary clarifiers into the South Platte River, lagoons
were constructed for the temporary storage of excess activated sludge. Sixteen
hectares of lagoons representing sixty million gallons of storage capacity pro-
vided temporary relief during the winter months of 1968 - 1969. By the spring
of 1969, anaerobic decomposition of the waste activated sludge stored in the
lagoons created serious odor problems. Neither the FDI units nor the temporary
lagoons provided an acceptable solution to the sludge disposal problem. Conse-
quently, a third alternative, land application of vacuum filter cake, was ini-
tiated in May of 1969.
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Land application of vacuum filter cake was originally conceived to be a
temporary expedient until the FDI units could be restored to their design
capability, By 1971 it was apparent that the cost of continued operation
and maintenance of the FDI units would be prohibitive. The most serious
problems occurred when the FDI units were being operated in the incinera-
tion mode. Although from a maintenance standpoint it would have been de-
sirable to operate the units in the drying mode only, this was not possible
for several reasons. The primary fuel source for the operation of the units
was natural gas with No. 2 diesel as a standby fuel. During the winter of
1969-1970, natural gas service was curtailed on many occasions, and Metro
did not have a sufficient allocation of standby fuel. This limited fuel
supply forced the District to incinerate sludge for its caloric value as
a substitute for commercial fuel.
It was originally anticipated that the City and County of Denver Parks De-
partment would use the dry sludge as a fertilizer. The physical character-
istics of the heat dried sludge were such that it could not be handled with
commercial fertilizer spreaders without causing dust problems. For this
reason the Denver Parks Department in the fall of 1969 refused to accept
any additional dried sludge. As no other large customer of dried sludge
existed in the area, it was necessary to cease drying and revert back to
the incineration mode even during periods when adequate fuel was available
for drying.
Operational limitations encountered during the incineration mode were odors,
as well as particulate and opacity air pollution problems. When the FDI
units were initially installed in 1966 they met all existing Colorado air
pollution standards. In 1970 these standards were revised drastically to
reduce stack emission concentrations from stationary sources. During 1971
the FDI units were operated under a temporary variance while modifications
were being made to meet the new standards. It soon became obvious that the
FDI units could not be economically modified to comply with the new stand-
ards. Because of air pollution, mechanical and fuel problems, the FDI units
were permanently shut down in August of 1971. Between May of 1969 and Au-
gust of 1971 the FDI units and the land application of filter cake were op-
erated concurrently. From August of 1971 to the present time the only me
of sludge disposal used by Metro has been land application.
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EVALUATION OF LAND APPLICATION TECHNOLOGY
In 1969 Metro acquired 64.8 hectares of land from the City and County of Den-
ver. This land had been sold to the City and County of Denver by the federal
government for the purpose of solids waste disposal. The land is located 42
kilometers southeast of the Metro treatment plant and was part of the LBR
(Lowry Bombing Range) (Fig. 2). The vegetation on this site was natural pas-
ture grass typical of the range land of Colorado. During 1969 and 1970 the
vacuum filter cake sludge, which could not be processed by the FDI units, was
transported by truck to the LBR site. The vacuum filtered sludge contained
15% TS and was transported in open 10 cubic meter trucks equipped with special
rubber seals to prevent leakage during transport.
In 1969 and 1970 two methods of operation were utilized, one for dry weather
and the second for wet weather. Metro hired a contractor to perform the ne-
cessary work under both modes of operation. The transportation of vacuum fil-
ter cake was the same for both dry and wet weather operations. During dry
weather the sludge was tail gated directly from the transport vehicle onto the
Snftfff
Fig. 1-Filter cake sludge is tail gated onto soil surface.
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/
CO
evj
1-70
f
t—Metro Treatment Plant
L—L/
..n
ludge Recycle-
1-70
5 miles / —
•.
Denver City
Limit
Fig. 2-Location map of Lowry Bombing Range sludge recycle site.
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surface of the soil, A D-6 Caterpiller equipped with a front mount blade
was then used to spread the sludge evenly over the surface of the soil to a
depth of approximately 2.5 centimeters, The sludge was then allowed to dry
for 24 hours. After the sludge had dried, an industrial-type (1.8 meter
wide) rototiller with a depth capability of 45,7 centimeters incorporated
the sludge into the soil. This operation was not always satisfactory for
the following reasons:
A) Rocks over 12.7 centimeters in diameter would lodge in the tiller
mechanism, causing shear pins and drive chains to fail; thus, ren-
dering the unit inoperable.
B) Dense vegetation over 1.2 meters tall would wrap up in the tiller
mechanism and plug the unit.
C) Wet soil would clog the tiller mechanism with mud and the unit
would become inoperable.
During warm weather, land application was cyclical, three weeks on and three
weeks off, which coincided with shutdown and routine maintenance of the FDI
units. In wet weather the sludge was dumped directly onto the surface of the
soil, and D-8 Caterpiller tractors with front mounted blades would intermix
the sludge with the soil. A satisfactory mix was accomplished when a ratio
of five or more parts of soil were mixed with one part of sludge. However,
during the winter months when the soil had frozen, the mixing of sludge and
soil was extremely difficult. It then became necessary to provide a ripper
behind the D-8 Caterpiller in order to keep ahead of the soil freezing prob-
lem. It was necessary to work 24 hours a day, 7 days a week. During winter
weather operation, the sludge was intermixed into the soil in the rolling
topography which lends itself to this type of operation. In these areas
large quantities of soil for intermixing with sludge were available within
a relatively short distance from the application site. Of the 64.8 hectares
originally acquired 36.4 hectares were actually utilized for sludge incorpor-
ation. A total of 30,600 dry metric tons were applied to the site in 1969
and 1970 for a loading rate of approximately 840 dry metric tons per hectare.
The exact sludge loadings to the area in 1969-1970 could not be determined
because of different application methods used at different seasons.
Peripheral surface water channels were dug around the 64.8 hectare site to re-
tain the water which ran off during snow or rain storms. During severe storms
the collection channels proved inadequate to contain all of the runoff. Metro
and the State Health Department sampled this runoff downstream of the site
during these periods. Analysis of the runoff samples did not indicate the
presence of contaminants from the land application site.
In April of 1970 Metro ceased application of sludge to the site because of
concern that the high loading rates might have an adverse effect on soil pro-
ductivity and erosion. The site was then graded using a rubber tired scraper
(between the fall of 1970 and the spring of 1971). In the fall of 1971 the
site was seeded using Brome and Crested Wheat grasses. During 1972 high
winds and generally dry conditions hindered growth of the grasses planted.
In the spring of 1972 the area was reseeded. Because vegetative coverage
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was incomplete, the area was again reseeded in the fall of 1972 with tiie
same mixture of grasses. By the spring of 1973 vegetative coverage exceeded
50% of the total area. Supplementary seedings were conducted during the fall
of 1973 and spring of 1974. By the spring of 1975 vegetative cover was vir-
tually complete. The complete revegetation process took three years. Reve-
getation was difficult because top soil had been removed and replaced with
subsoil (no sludge was incorporated into the soil) and moisture was marginal.
Annual precipitation averages 35.6 centimeters per year and irrigation water
was not available.
The major problem involved in the 1969-1970 operation was vulnerability to
adverse climatic conditions. There were several occasions during the winter
of 1969 and 1970 when snow blizzards required cessation of sludge incorpora-
tion. The equipment operators and truck drivers could not reach the site be-
cause of snowdrifts. The dry weather operation costs were much lower than
the wet weather costs. During dry weather one rototiller could incorporate
the total daily sludge production. Six D-8 Caterpillers were required to
mix the total sludge production under the wet weather operations.
Recognizing that the FDI units could not be modified and operated to comply
with the Colorado air pollution standards, Metro in 1971 revised the land ap-
plication operation to provide for a continuous year-round disposal of the
total sludge generated. For this purpose, Metro received permission to use
an additional 259.2 hectares of pasture land at the LBR from the City and
County of Denver.
Based on the experiences during 1969 and 1970 with the land application of
sludge, several changes in sludge application methodology were adopted. Metro
purchased the equipment necessary for the land application system, and uti-
lized District personnel to operate this equipment. The method of operation
consisted of transporting the filter cake from the treatment plant to the LBR
in the same type of vehicle used in the previous operation. These vehicles
were equipped with special seals to prevent accidental leakage during trans-
port. A ramp was constructed at the application site which allowed the trans-
port vehicles to transfer the sludge directly into spreaders. The 10 cubic
meter farm manure spreaders were sized to accommodate one truckload of sludge.
The spreaders were modified with special seals to handle the relatively wet
vacuum filter cake to keep the sludge from flowing onto areas where it was
not desired (Fig. 3). Special lighting was provided at the ramp to allow for
operation 24 hours per day with two spreaders and one tractor. A standby
tractor was rented for the purpose of allowing the primary unit to be serviced;
thus, enabling operations to continue 7 days a week. Sludge was spread onto
the surface of the grass and usually dried within one-half hour after appli-
cation. After each application of 6.7 dry metric tons per hectare a spike
tooth harrow was used to break up any large particles into fine particles.
Cattle continued to graze the pasture during this operation.
In 1971, 115 hectares of the 260 hectares acquired earlier were used for
sludge application. A total of 8,539 dry metric tons of solids were applied
to the site resulting in a loading of approximately 74 dry tons per hectare.
Soil and surface water monitoring during 1971 indicated that there had been
8
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Fig. 3-Sludge being transferred to 10 cubic meter manure spreaders-.
no contamination as a result of Metro's operation at this site. A major
advantage of this method was that the operation did not disturb the native
vegetation. Based on visual observations the vegetative production at this
site improved compared to the surrounding area that did not receive sludge
applications. Another major advantage of this operation was that it was
far less expensive than the incinerator drying operation (Table 1). This
method was also environmentally acceptable from the standpoint of soil
conservation, air pollution and odor problems.
At the direction of the District Board of Directors, in November of 1972
Metro entered into a two year contract with a private contractor, Landfill,
Inc. to provide services for land application of sludge utilizing the same
technology which Metro staff had developed. Concurrently, Metro acquired
an additional 260 hectares of land from the City and County of Denver for
a total of 583.2 hectares.
The contractor utilized larger transport vehicles, 30 cubic meter units, and
constructed a large sludge storage hopper to store sludge from the transport
vehicles until it could be transferred into the spreader trucks (Fig. 4).
The spreaders used by the contractor were also larger (15 cubic meters) than
those used during the previous operation (Fig. 5). Each spreader was mounted
on a large truck chassis previously used in open coal pit mining (23,622 kilo-
gram rear axle capacity). The farm fertilizer spreaders were modified to
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able 1-Comparison of incinerator versus land application sludge disposal
costs (1971)
iot«i o ( H
Sludat Operations and
disposal Tons maintenance cost Unit 0 t M cost Capita Mmprovemwt capital costs Total unit
cost S/year $/year costs $/ton differentiation
method disposed
Vyear
$/ton
Sludge
Indn.
14,649
351.900
24.00
122.000
473.900
32.35
721 higher than
land application
Land
appl.
15.05d
257.700
17.11
25.000
282.700
18.77
Total 29.707
609,600
20.52
147,000
756,600
25.46
Fig. 4-Transport vehicle dumping into sludge storage hopper.
10
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-
• •«. ••..***-*••
«_..
Fig. 5-Modified fertilizer spreader spreading sludge.
handle the relatively wet filter cake. During the fall and winter of 1971
and 1972 the contractor spread the sludge thinly over the grassland. In
early spring of 1972 the contractor experienced difficulty with access to
the field. As a result, large quantities of vacuum filter cake were stock-
piled to a depth of 1.2 meters in a depression near a dry stream bed on the
site. After completion of the stockpiling of filter cake, snowstorms oc-
curred which covered the stockpiled filter cake. Metro inspectors were un-
aware of the unauthorized modification of the method previously agreed upon.
As the snow began to melt, the stockpiled sludge began to decompose creating
odor nuisances to people living in the area adjacent to the site. During
late spring when the area had dried, small smoldering fires started in the
areas which had received many consecutive sludge applications, a result of
careless smokers and heavy equipment operating in the area. The smoldering
fires were difficult to extinguish particularly during high winds.
Complaints to the Arapahoe County Commissioners made by residents living in
the adjacent area resulted in a Public Hearing on June 20, 1972. At the Pub-
lic Hearing Metro proposed a new method of land application to eliminate the
odor and fire hazards previously experienced. This proposal was approved by
the County Commissioners and implementation began in June of 1972.
11
-------
&**£* •«*»»
«S€
Fig. 6-Mold board plow incorporating sludge.
The revised method consisted of applying the filter cake to the land at a
depth of 5 to 8 centimeters (approximately 74 dry metric tons per hectare),
and within six hours of application incorporating the sludge to a depth of
25 centimeters using a 41 centimeter mold board plow or a 76 centimeter disc
plow (Fig. 6). After sludge incorporation the soil was tilled with an off-
set disc several times until a suitable seed bed had been prepared. As the
native vegetation is disturbed by this method the soil is seeded with wheat
or other forage crops such as sudan or oats to provide a vegetative cover
protect the soil from wind and water erosion. Because germination is inhi-
bited if the soil is seeded immediately after sludge incorporation, the soil
is allowed to set or incubate for 2 months before seeding. With the assis-
tance of the Soil Conservation Service staff a plan was developed to estab-
lish permanent contours on the entire application site. One or more crops
are raised each year to provide food for the grazing cat-
soil erosion.
Since 1972 this method has been providing satisfactory control of the odor
and fire problems previously experienced. While this method is satisfactory
during dry weather, special modifications had to be adapted during winter op-
erations In the fall of 1972 an additional 260 hectares were acquired for
the expressed purpose of inclement weather incorporation.
12
-------
spread on the land by tailgating to a depth of 60 centimeters and intermixed
with the soil at a ratio of five parts soil to one part sludge, Since 1973
the inclement weather site has been prepared in advance by bench and terrac-
ing the area. Sludge loadings to the inclement weather site have exceeded
670 dry metric tons per hectare per year. Each inclement weather site is
loaded only once. Inclement weather application generally takes place dur-
ing December, January and February depending upon the severity of the winter.
During the relatively mild, dry winter of 1974-1975 the inclement weather
site was required for only 30 days during January and February.
13
-------
EVALUATION OF SLUDGE EFFECTS ON THE LOWRY BOMBING RANGE
TYPE OF SLUDGE
If sewage sludge is to be utilized as a soil conditioner or fertilizer, pa-
rameters such as nutrient content, metals, conductivity, pH and organic mat-
ter should be known in order to evaluate effects on subsequent plant growth.
When sludge is applied to soil, one of its immediate benefits is its N (ni-
trogen) and P (phosphorous) content. Because much of the N is tied up in
the organic fraction it becomes a valuable source of slow release N. In ad-
dition to macro-nutrients such as N and P, sludge is a valuable source of
micro-nutrients such as Zn (zinc), Cu (copper), B (boron) and Mo (molybdenum)
when applied at low rates. The stable organic matter contained in sludge be-
comes a benefit by acting as a soil conditioner, which increases soil CEC
(cation exchange capacity), water holding capacity, infiltration rates and
the general tilth of the soil.
Potential problems that could arise from heavy applications of sewage sludge
include inhibition of germination from excess salts, phytotoxicity from heavy
metals, excess N and P, pathogens, and odors.
The sludge sources that comprised the vacuum filter cake incorporated into
the soil at the LBR included:
A) Raw primary sludge - 40% of total.
B) Waste activated sludge - 45% of total.
C) Anaerobically digested primary sludge - 15% of total.
This sludge mixture was dewatered by applying FeCIS (8-12!% of dry weight) and
slaked lime (20-30% of dry weight). In the fall of 1973, cationic polymers
were substituted in part for the FeCl3 and lime. The amount of polymer re-
quired (4.5 to 6.8 kg/0.9 metric ton dry weight) was insignificant compared
with the approximate 30% chemicals added to the vacuum filter feed when FeCIS
and lime were applied. Thus, the polymer conditioned vacuum filter cake re-
presents the average chemical composition of the sludge without chemicals.
Summarized in Table 2 are the arithmetic means and standard deviations for
all of the chemical constituents analyzed in both types of vacuum filter cake
for the years 1972 through 1975.
Major differences between the two types of filter cake are as follows:
1. pH; FeCl3 and lime cake =11,4 versus 6.6 for polymer cake.
14
-------
Table 2-A comparison of chemical composition of ferric chloride and lime
treated vacuum filter cake with polymer conditioned
vacuum filter cake (1972-1975 data)
Analysis Units
pH Units
Volatile frac-
tion % of TS
Conductivity umho/cm
Ag mg/kg-dry wt.
As
B
Ba
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hg
K
Li
Mn
Mo
H (TKN)
Na
Ni
P
Pb
Se
Sn
Sr
T1
U
V
Y
Zn
Zr
Vacuum filter
W/FeCl3 + 1
Mean
11.4
54.9
9,790
' 51
17
53.5
440
10
87,380
18.9
77
480
770
34,160
4.7
4,800
20
355
19.3
38,640
6,300
290
16,700
491
7
135
310
1,275
8
70
25
1,305
153
cake
ime
+_ S.D.*
0.9
6.2
3,087
22
-
12.0
141
-
26,720
14.2
32
262
295
9,330
3.8
-
-
160
7.0
8,230
-
129
5,400
312
-
17
128
206
-
-
6
719
56
Vacuum filter cake
W/polymer
Mean
6.6
69.6
4,820
-
-
-
-
21 ,800
13.0
-
711
924
7,120
-
-
-
215
-
56,415
-
344
21,570
568
-
-
-
-
-
-
-
1,864
—
+_ S.D*
0.8
5.6
1,820
-
-
-
-
11,690
10.4
-
346
234
2,860
-
-
-
112
-
11 .930
-
132
10,700
199
-
-
-
-
-
-
-
224
—
* Standard Deviation
15
-------
2. Percent volatile solids: FeClS and lime cake = 54.9% versus 69.6%
for polymer cake.
3. Electrical conductivity (umho/cm): FeCl3 and lime cake = 9,790
versus 4,820 for polymer cake,
4. Calcium: FeCl3 and lime cake = 87,380 ppm versus 21,800 ppm for
polymer cake (dry weight basis).
With regard to plant nutrients, the high pH of the FeClS and lime treated
sludge resulted in significant losses of volatile ammonia (NH3), as was evi-
dent by the strongly pungent NH3 odors prevalent in the vacuum filter process
building during treatment with FeClS and lime. Although dilution of the fil-
ter feed with chemical may have accounted for part of the reduction in N con-
centration (from 5.67% N in polymer cake to 3.86% N in FeCl3 + lime cake) the
32% loss in TKN (total Kjeldahl nitrogen) was in great part due to NH3 volati-
lization. The 22% reduction in P concentrations is attributable to the dilu-
tion effect with additions of FeClS and lime.
Average sludge loadings have been at the rate of 67.2 metric tons/hectare/-
year which would mean that approximately 2,600 kilograms of N/hectare/year
have been applied with the addition of FeCl3 and lime cake compared to 3,800
kilograms of N/hectare/year for the polymer cake. Sludge has been applied an-
nually to much of the area since 1969; thus, N has been applied far in excess
of crop needs.
SOIL EFFECTS OF SLUDGE DISPOSAL AT THE LOWRY BOMBING RANGE
The LBR sludge and disposal area is located east of Denver in Arapahoe County,
Colorado. The county has a warm, semi-arid climate that is typical of the
High Plains; thus, rainfall averages 35.6 centimeters, while the average annual
temperature is about 10°C.
The dominant soils at the LBR are the Fondis and Renohill series. The Fondis
soils are deep well drained soils located on uplands, and formed from loessol
deposits overlying the Dawson formation (Pleistocene Age) (1). The Fondis sur-
face soil is about 10 centimeters thick, free of lime, very dark grayish-brown
and silt loam to silty clay loam in texture. The subsoil is 102 to 114 centi-
meters thick, contains free lime, dark yellowish brown and silt loam to clay
in texture. The Fondis soils have moderately slow permeability, slow internal
drainage and high available water holding capacity. The Renohill series which
has developed on the Dawson formation is a moderately deep well drained soil
(1). The surface layer is about 10 centimeters thick, free of lime, and is a
dark brown loam. The subsurface soil is approximately 63 centimeters thick,
contains free lime, dark brown to dark yellowish brown in color, and ranges
from a loam to silty clay loam in texture. Renohill soils have medium inter-
nal drainage, moderately slow to slow permeability and moderate water holding
capacity.
Starting in 1972 an attempt was made to monitor and evaluate the degree of
possible soil pollution from excessive salts or heavy metals after continuous
sludge applications. A general survey, which examined a number of soil cores
16
-------
to a depth of 0.9 meters was taken semi-annually. Soil samples, which repre-
sent only one sample point from each area, were analyzed for pH, conductivity,
nitrate nitrogen (N03-N), ammonium nitrogen (NH4-N), sodium bicarbonate extrac-
table P, ammonium acetate extractable K, chlorides (Cl) and diethlenetriamime-
pentacedic acid (DTPA) extractable Zn, Fe, Cu and Mn (see Appendix A).
Site 1 was a control area, while sites 2 through 7 were areas that had received
varying amounts of sludge (see Fig. 7).
Soil samples collected in November of 1974 had total sludge loadings varying
from 0 to 542 metric tons/hectare. Heavy metal analysis and pH for surface
soils (0 - 15.24 cm) from the November 1974 sampling are shown in Table 3. Sub-
surface soils are not included in the table since there was no apparent leach-
ing of metals below the surface (see Appendix A for subsoil analysis).
Table 3-Concentrations of DTPA extractable Zn, Fe, Cu, Mn and pH from sludge
additions to surface soils (0-15.24 cm) at the Lowry Bombing Range*
Site 1
1A
IB
1C
?A
6A
66
3A
38
3C
4C
2C
2B
5C
4A
4B
SB
5A
7
7
pH
.5
.6
7.1
7
7
7
7
6
7
7
6
7
7
7
7
7
7
.5
.5
.9
.1
.4
.7
.5
.5
.3
.0
.1
.3
.8
.3
Zn
0.
0.
0.
10.
10.
15.
41.
33.
16.
56.
19.
8.
85.
28.
15.
45.
68.
8
6
6
5
2
2
5
0
0
0
0
3
0
0
5
0
0
8
6
15
Fe
.9
.0
.2
20.2
21
.6
17. a
59
25
6d
67
64
24
8
65
30
71
72
.0
.7
.0
.0
.5
.4
.8
.0
.5
.0
.0
Cu
0.
0.
0.
5.
6.
9.
17.
12.
12.
35.
5.
5.
4.
12.
7.
42.
10.
7
6
7
4
8
6
5
6
5
0
9
7
0
0
4
0
0
Mn
13.
6.
13.
17.
8.
10.
18.
98.
99.
31.
34.
15.
85.
60.
15.
26.
26.
Estimated tons of
sludge applied/hectare (dry wt.)
7
9
2
0
5
0
5
0
0
0
0
0
0
0
0
0
0
0
0
0
74
74
130
143
143
143
184
195
202
267
323
381
461
542
*So11s sampled 1n November 1974.
The concentration of the various chemical constituents examined did not reflect
the estimated sludge loadings to each site; thus, it can be concluded that the
sludge application is extremely variable, or that the sludge soil mix is not
adequate.
An examination of data from site 5C demonstrates the extreme heterogeneity of
the sludge-soil mix within one field. Analysis of a soil sample taken in May
of 1974 is compared with the analysis of a soil sample from the same field col-
lected in November of 1974 (Table 4). There were no sludge applications to
17
-------
CXI
-------
this field between these sampling dates. None of the chemical constituents
examined are similar.
Table 4-Comparison of chemical constituents of soil samples from site 5C sampled
in May Iy7t and Novemuer li»74
Analysis
Units
May 1974
November 1974
PH
Conductivity
Zn (DTPA)
Fe (DTPA)
Cu (DTPA)
Mn (DTPA)
H03-N
MK4-N
TKN
P
K
units
mmho
mg/kg
rag/ kg
mg/kg
mg/kg
mg/kg
mg/kg
%
mg/kg
mg/kg
7.4
3.6
.95
6.2
1.47
8.50
240.0
12.0
0.31
385.0
358.0
7.0
15.4
85.0
8.8
4.0
85.0
1000.0
11.0
0.52
450.0
480.0
The range in DTPA extractable metal content for Zn (See Table 3) is from 0.6
Ppm in the control to a high of 85.0 ppm at a 267 metric ton/hectare applica-
tion, while Cu ranges from 0.6 ppm in the control to 42.0 ppm at a 461 metric
ton/hectare application. It is interesting to note that the soil sample from
site 5C (November 1974 sampling) apparently had the highest loading of sludge,
as can be seen from the high Zn, Mn, N, P and conductivity levels (see Tables
3 and 4); however, the concentration of DTPA extractable Cu is quite low. The
low extractability of Cu in this sample is probably a reflection of the high
absorption or chelating capacity of the organic matter for Cu. Whether this
statement is true is unknown since the total metal content of the soil samples
was not determined. However, this example tends to point out the falibility
in trying to analyze the toxic metal status of a soil when employing an ex-
traction technique which only examines some fraction of the total metal present,
Whether the levels of metals encountered in this survey (many of which are re-
latively high) could produce phytotoxic effects on the plants growing on these
soils is unknown, since plants growing on these sites were not collected for
analysis of metals, nor were yield determinations made. It can only be noted
that the wheat crop growing on these sites appeared to be healthy.
Soil pH at the Lowry Bombing Range naturally ranges from about 7.0 to 8.0.
Sludge additions had little effect on lowering the soil pH, which reflects the
saturation with calcium carbonates in these soils.
Soil conductivity shown in Table 5 is like the metal data, extremely variable,
19
-------
ranging from a low of 0.5 mmho/cm in the control area to a high of 15 mmho/-
cm at site 5C. About one-third of the sites with' sludge applications showed
conductivity levels from 4 to 14 mmho/cm which could be considered injurious
to some of the crops grown in this area.
Table 5-Concentrations of N03-N, NH+-N, TKN, P, K and conductivity from sludge
additions to surface soil! (0-15.24 cm) of the Lowry Bombing Range
ma/ka (dry vyt.) %
Site *
1A
IB
1C
2A
6A
6B
3A
3B
3C
4C
2C
2B
5C
4A
4B
t.B
5A
N03-N
1
1
1
2
46
32
570
600
400
330
435
6
1000
220
160
3aO
680
NH^-H
21
14
10
12
20
20
32
30
19
9
47
10
11
19
23
22
32
TKN
.116
.159
.078
.174
.136
.145
.292
.238
.243
.280
.197
.150
.520
.219
.162
.297
.341
ing/ kg
(dry wt.)
P
22
4
17
80
125
175
385
325
225
440
120
72
450
16b
115
345
450
ijimho
K Conductivity
393
325
265
650
425
342
700
1080
700
580
405
393
480
418
405
363
363
.6
.5
1.1
1.2
1.8
1.4
8.7
9.2
1.7
6.8
8.7
.9
15.4
.9
2.8
4.1
8.5
Estimated tons/ha
applied
(dry wt.)
0
0
0
74
74
130
143
143
143
184
195
202
267
323
381
461
542
Soils in this area are naturally high in K and rarely require any K fertiliza-
tion for crop production. The addition of sludge has increased the extractable
K levels in all cases (see Table 5), but not to a detrimental level.
Sludge applications have increased the available P content to high levels
(see Table 4), but it is doubtful that these levels are detrimental to crop
growth since there is a more than adequate supply of available Zn, Cu, Mn and
Fe which would tend to offset any P induced Zn, Cu, Mn or Fe deficiencies.
Two factors play a role in the extreme -variability of N content of the sludged
soils at the LBR. The first factor is the extreme heterogeneity of tne sludge-
soil mixture which has already been noted. The second factor is that the sludge
itself is extremely variable. From Table 1 it can be seen that the dewatering
process used at the treatment plant (FeCls + lime versus polymer will affect
the N content of the sludge; thus the average N content of the sludge varies
from about 3% to 6%.
20
-------
Continuous sludge applications since 1969 have increased the N content of the
soil (see Table 6) to excessive levels, beyond any capacity for crop removal.
Immediately available N (NOs-N + NH4-N) ranges from a low of 31,4 kilograms
per hectare at site 2A to a high of 113^.3 kilograms per hectare at site 5C.
If only 3/o of the TKN becomes available for plant uptake during the growing
season, then site 2A contains a total of 135.4 kilograms per hectare of avail-
able N while site 5C contains 1444 kilograms per hectare. Because of these
high rates, N has leached below the rooting zone. Summarized in Table 6 are
N03-N, NH/j-N and TKN data for the 61 to 91 centimeter depth. The leaching
rates do not appear to be excessive, and it is doubtful that N03 from sludge
applications would ever pollute the ground water. Rainwater in this area is
insufficient (approximately 36 centimeters per year) to percolate to any sig-
nificant depth, and potable water is from 100 meters to 300 meters deep which
is protected by impervious stratum within the Dawson formation.
Table 6-Concentrations of NOj-N, NHL-N and TKN from subsurface soils (61 to 91
cm depth) at the Lowry Bombing Range.
ppm
Site 1
1A
IB
1C
2A
6A
6B
3A
3B
3C
4C
2C
2B
5C
4A
4B
SB
5A
N03-N
1
1
13
5
1
2
42
33
28
34
3
1
21
3
25
61
51
NH4-N
7
15
5
10
15
15
7
7
13
9
11
7
14
19
21
19
19
I
TKN
.029
.028
.024
.033
.026
.022
.043
.063
.060
.034
.038
.027
.032
.033
.034
.030
.035
Cl
<2
2
22
2
8
25
15
8
5
22
2
10
2
20
8
5
8
Estimated tons/ha
applied (dry wt. )
0
0
0
74
74
130
143
143
143
184
195
202
267
323
381
461
542
21
-------
Grab samples of soil and leaf tissue from winter wheat (Wichita) were col-
lected from the LBR on May 31, 1974, Results of total metal analysis are
shown in Table 7, The plant and soil samples were digested in a nitric-per-
chloric acid mixture and metals determined using atomic absorption. The
plant samples were not washed prior to analysis, nor was background correc-
tion applied during the analysis of Cd, Pb or Ni. However, none of the me-
tal concentrations reported in Table 7 would be considered out of the normal
elemental composition range for plant materials,
Table 7-Total metal composition of soil and wheat from the Lowry Bombing Range
Site 1
Soils:
1
2
3
4
5
6
Plant tissue:
1
2
3
4
5
6
Zn
59
53
125
60
80
205
19
16
23
46
56
55
Cu
24
18
40
22
25
54
5.6
8.4
10.6
12.7
15.4
36.2
mg/ktj_ (dry wt.
Ni
16
16
25
20
20
21
5.5
4.0
4.6
4.8
5.6
8.6
)
Cd
ND*
NO
.45
.35
.30
1.20
.12
.12
.19
.41
.22
.34
Pb
25
20
30
20
25
48
5.7
3.4
3.3
3.3
6.6
5.2
*ND - not detected
22
-------
RESEARCH AND DEVELOPMENT
By 1971, it had become apparent that land application of filter cake was not
to be a temporary expedient in place of incineration, but a long term neces-
sity. Metro staff therefore contacted the Agronomy Department of Colorado
State University (CSU) at Fort Collins, Colorado to investigate the various
aspects of sludge loading rates, as well as other conditions necessary for
beneficial utilization of nutrients in sewage sludge.
The goals of this research effort included:
1. Investigation of alternative land application and incorporation
methods.
2. Environmental monitoring of soil, plants, ground water and air.
3. Evaluation of various crops that could benefit from optimal loadings
of sludge to soil.
The information from this research was to be made available to that segment
of the farm community wishing to apply sludge to their land in the proper
season and amount.
In 1971 a contract was signed with the CSU Department of Agronomy and Danford
Champ!in Farms for a 0.81 hectare research site at Watkins, Colorado to inves-
tigate the effects of various sludge loadings on plant germination and growth.
Results from this experiment led to greenhouse experiments using a range of
crops including millet, wheat and sorghum sudangrass hybrid. These crops were
subjected to various sludge loadings and various incubation periods between
sludge application and seeding.
On the basis of results obtained from these projects as well as recommendations
of Metro's consulting engineers to utilize the semi-arid climate and evapora-
tion capacity in Colorado for air drying, an investigation of air drying of an-
aerobically digested sludge in drying basins at the CSU agronomy farm at Fort
Collins was initiated in 1973.
Obnoxious odors experienced during some of the early research work at Watkins
led to investigation of various subsurface injection devices which would in-
ject liquid sludge beneath the soil surface to avoid aesthetic and odor prob-
lems. Therefore, liquid sludge was injected into the soi! at Watkins, Colo-
rado. Two injection devices were used, one owned by Danford Champlin farms
and one designed by James Smith of CSU; both devices worked well and no odor
problems developed when these devices were used.
23
-------
LAND APPLICATION OF METRO SEWAGE SLUDGE AT WATKINS, COLORADO: EFFECT
ON GROWTH AND CHEMICAL COMPOSITION OF PLANTS*
Objectives of the Study
1. To determine the maximum application rate of the Metro sewage sludge
to the sandy soils of western Adams County, Colorado consistent with
continued crop productivity without causing heavy metal, organic or
pathogenic pollution of soil or water,
2. To determine the extent of leaching and/or accumulation of substances
derived from sewage sludge applied to soil.
Materials and Methods
A field study was set up on a Truckton sandy loam soil in western Adams
County. Soil characteristics before sludge application are shown in Table
8. These are deep soils with loamy sand surface layers and loamy subsoils
that grade into sand at depths of 50 to 76 centimeters. They are on ter-
races and uplands, and are developed from sandy alluvium washed from the
arkosic sandstones to the south. Wind has reworked the sandy alluvium in
most areas developing an undulating to rolling topography. About one-thir
of the area of this soil has slopes less than 3% and two-thirds is rolling
and slopes an average 6%.
Table 8-Characteristics of the Truckton loamy sand used in the study
~~a) b) F1eld
- X Textural"' CECU' Infiltration 0 M c)
s*lt Clay Class m.e./lOO gtn rate cm/hr j '
rd
Sand
14 8 Loamy Sand 5.2 12.7 TTj
Extractable - ppm
Oj-Nd) i0 -f> 1°9) Cu9) Feg) Mng)
3 10 12° 2 1 12 12
a) Pipette Method. OH oxidized by H202, dispersed with Calgon.
b Determined by the ammonium acetate described by Jackson.
c Determined by the chromic acid method described by Jackson.
d Determined by the phenoldisalfonic acid method described by Jackson.
e) Determined by the ascorbic acid method described by vatanabe et al .
f Determined by the ammonium acetate method described by Pratt."
g) Determined by the DTPA method described by Lindsay et al..
*This research was conducted for Metro by B.R. Sabey and W. Hart of Colorado
State University, parts of which were published by them in the Journal of
Environmental Quality, 1975. 4:2:252:256.
24
-------
Plots (3 meters x 9.6 meters) were prepared by leveling the areas and build-
ing levees around each individual plot sufficient to contain the applied li-
quid sludge. Measured quantities of sewage sludge (approximately 5% solids)
were pumped from tank trucks onto the plots on May 18 and 19, 1971, An
analysis of the sludge is shown in Table 9. The liquid sludge as applied was
approximately 50% primary anaerobically digested and 50% aerobically digested
sludge.
Five ratios of liquid sludge ranging from 0 to 40.6 centimeters in depth were
applied to each cropping situation in a single application prior to seedbed
preparation. Amounts of liquid sludge applied were equivalent to 0, 25, 50,
100 and 125 metric tons/ha (dry weight). Three cropping situations - fallow,
sorghum sudangrass hybrid (sorghum bicolor x s. sudanense) CV. NB 230 S,
and millet (Panicum milacium L.) CV Leonard were initially used. Each treat-
ment was replicated four times in a randomized block design giving a total of
60 plots. In addition to these 60 plots, 12 more plots received applications
of filter cake sludge varying from 27 metric tons to 112 metric tons/ha (dry
weight). Plot design layout with loading rates is shown in Fig. 8.
Table 9-Typical analysis of anaerobically and aerobically digested sewage
sludge produced by Metropolitan Denver Sewage Disposal District No. 1
Anaerobically digested
primary sludge
total solids-b.7?
t Irrnent
N (organic)*
p..
K"
Ti***
Cr
Hn
Fe
Co
N1
Cu
Zn
Br
Rb
Sr
r
Zr
Mo
AG
Cd
Sn
Ba
Pb
U
As
Se
Dry weight
2.8
1.3
1.1
0.18
0.021
0.035
1.7
0.001
0.0?4
0.13
0.40
0.002
0.004
0.037
O.C10
0.041
0.006
0.007
0.003
0.020
0.17
0.17
0.002
-
-
mg/1
Wet weight
1600
741
627
103
12
20
970
0.60
14
74
228
1.1
2.3
22
5.7
23
3.4
4.0
1.7
11
97
97
1.1
-
-
Aerobically digested
activated sludge
total solid-,-4.4%
1
Dry weight Wet
6.6
3.1
1.3
0.18
0.065
0.035
1.0
0.001
0.025
0.23
0.48
0.003
0.003
0.023
0.004
0.014
0.001
0.011
0.009
0.016
O.OS4
0.093
-
0.002
0.006
waste
mg/1
weight
2900
1360
572
79
29
15
440
0.44
11
101
211
1.3
3.5
10.1
1.8
6.2
0.44
4.8
40
7.0
37
41
-
0.83
2.6
Typical historical analysis, mean of many detemiinations.
Quantitative analysis conducted by Industrial lab^iM Lories, rvean of two
analyses.
Remainder of analyses conducted by Industrial Laboralories. Qualitative
analyses by fluuiescence x-ray spec Irophotoine try. mean of four analyses.
25
-------
Sorghum sudangrass plots
llOOT/ha
[ 50T/ha|
llOOT/ha
[200T/ha
1 25T/hal
50T/ha
lOOT/ha
25T/ha
JOOT/ha
lOOT/ha
OT/ha
lOOT/ha
25T/ha
50T/ha
OT/ha
OT/hal
lOOT/ha
50T/ha
OT/ha
25T/ha
Millet plots
I 50T/ha| [l?5IZ.hal*i OT/ha I* llOOT/ha
QT/ha | [sOT/hal I 25T/ha I tlOOT/ha
[JOOT/hal [ 25T/ha| I 50T/ha | |lOOT/ha
Filter cake plots
95T/ha 1 [ 45T/ha| [ 87T/ha| jlGU/ha
I 63T/hal I 40T/hal ll03T/ha
27T/hal l54T/hal 1 65T/ha
Fallow plots
25T/hal llOPT/ha I [l25T/h
LzST/hal I bOT/ha I llOOT/ha
*Infiltration measurements made on
these plots.
Fig. 8-Plot design layout with
identification and loadings
(dry metric tons per hectare)
of each plot.
26
-------
It was expected that the moisture in the sludge would soak into the soil
causing the sludge to dry rapidly, However, it took considerably longer
than anticipated (about 4 to 6 weeks) for the sludge to dry (the plots with
the highest rates remaining moist longest). In the interim, there were
distinct odor and fly problems which led to the conclusion that high rates
of a mixture of anaerobically stabilized and waste activated sludge could
not be applied to the soil surface and allowed to dry.
When the sludge had dried, it was mixed into the top 14.4 centimeters by ro-
totilliny. Soil samples were taken during the last week of June at various
depths down to 0.76 meters. A seedbed was prepared by tandem discing and
the sorghum sudangrass and millet were planted on July 5, 1971 a date that
was later than optimum.
A sprinkler irrigation system was installed to supplement rainfall. Adequate
moisture was provided for seed germination and for the prevention of crusting.
Irrigation of approximately 5.6 centimeters and 7.1 centimeters were applied
on July 12-14 and July 21-23 periods, respectively. These irrigations were
in addition to rainfall of approximately 3.81 centimeters during the month of
July 1971.*
Germination and emergence counts on the sorghum sudangrass and millet plots
were made on July 20, 1971. The counts were made on three rows each 8.6 me-
ters long. These data showed poor germination but since it was too late to
reseed and reseeding immediately would probably not have been much more suc-
cessful, it was decided that the project would be extended by planting winter
wheat in the fall.
The sorghum sudangrass was harvested on September 3, 1971 in spite of poor
germination and two hail storms. The green and dry weight yields were deter-
mined. A separate random sample was taken from each plot, dried and finely
ground for a total N determination. The millet was not harvested because of
severe hail damage.
Soil samples were taken at various depths down to 2.4 meters on September 14
and 15, 1971 prior to tillage and seedbed preparation for the wheat crop. The
soil samples were analyzed for N03-N, sodium bicarbonate extractable P, ammoni-
um acetate extractable K, DTPA extractable Zn, Fe, Cu and Mn.
After harvest of the sorghum sudangrass plots, all the plots were disced and
a seedbed for winter wheat was prepared. Wheat was planted on October 3 on
all 72 plots. Wheat germination and emergence counts were made on October 15,
1971.
On November 30, 1971 a limited number of plots were sampled to a soil depth of
10.16 centimeters for bacterial counts. Numbers of total aerobic, total coli-
form, fecal coliform, and fecal streptococci bacteria were determined by dilu-
*The reported value is the average rainfall of the Denver WSO, Byers, and Ft.
Lupton U.S. Weather Bureau stations for the month.
27
-------
tion counts using a membrane filter technique with the following (Difco
Laboratories) media for each group:
1. Total bacteria: M-plate count broth. 17 gm in 1000 nil of distilled
H20. Autoclave 15 minutes (15 Ibs. pressure and 121°C). Use 2.2 ml
per absorbent pad. Incubated 18-24 hours.
z- Total coliform: M-Endo broth-MF. 48 gm in 1000 ml distilled H^O con-
taining 21 ml ethanol. Heat to boiling. Cool. 2 ml to each sterile
absorbent pad. Incubate at 35°C for 24 hours.
3- Fecal coliform: M-FC broth. 3.7 gm in 1000 ml distilled H20. Add 1
ml of~"I%~"Tosol"ic acid in 0.2 N NaOH. Heat to boiling. Cool. Use 2
ml per sterile absorbent pad. (Cultures incubated by submerging in
44,5°C water bath for 24 hours.)
4- Tota] streptococci: M-Enterococcus Agar. 42 gm in 1000 ml distilled
H^O. Heat to boiling to dissolve completely. Disperse into petri
dishes and allow to solidify. Incubate for 48 hours at 35-37°C.
During the fall of 1971 it was decided to omit irrigation during the spring
of 1972. The wheat grew well in the spring until hot dry weather threatened
to eliminate the wheat yields, whereupon the decision was made to irrigate
to save the crop and obtain some yield data. However, yields had already
been severely depressed.
The wheat was harvested on July 14, 1972 and yields determined. Some subsam-
ples of the grain were separated and finely ground in a stainless steel Wiley
Mill for determinations of total N, P, K, Ca, Mg, Zn, Fe, Cu, Mn, Pb, B and
Cd. Total N was determined by macro-Kjeldahl digestion using Kel Pak #2 as
a catalyst, and distillation into boric acid. Phosphorus determinations were
made following nitric-perchloric digestion colorimetrically using ammonium
vanadate and ammonium molybdate. Potassium, Ca, Mg, Zn, Cu, Mn, Cd and Pb
were digested with nitric perchloric acids, diluted and read on an atomic
absorption spectrophotometer. Boron was determined by dry ashing at 550°C
with ash dissolved in 0.1 N HC1 and color development with circuminaxalic
acid. The color intensity was read on a spectrophotometer.
Infiltration measurements were made on four adjacent millet plots (see Fig.
8) in late July of 1972. These were chosen because they are adjacent to one
another, thus, eliminating as much as possible the effects of soil variations
in the measurements. Six unbuffered ring infi 1 trometers were installed in
each plot and the cumulative infiltration (up to 10.16 centimeters total ap-
plication) was determined as a function of time.
Results and Discussion
After application of the sewage sludge on the bordered plots, it took almost
six weeks for the sludge to dry at the soil surface. This resulted in an ap-
preciable odor and fly problem until the drying was completed. The conclusion
that this sludge (a mixture of anaerobic and aerobically digested sludges)
28
-------
could not be judiciously applied to the soil surface was reached, The aero-
bically digested waste activated sludge was not sufficiently stable to pre-
vent odor and fly problems.
Germination and emergence data for the sorghum sudangrass, millet, and wheat
grown on the field plots are shown in Tables 10 and 11. It is apparent that
increasing amounts of sewage sludge increased inhibition of germination and
emergence of sorghum sudangrass and millet. However, when the wheat was
planted some five months later, the factor causing germination and emergence
inhibition had been eliminated or dissipated, even at the higher rates of
sludge application. There were no significant differences between the con-
trols and sludge applied plots on germination and emergence of wheat.
Table 10-Germination and emergence counts on July 20, 1971 for three rows,
each 7.65 meters long
No. of plants (mean of 4 reps ._]
No. of plants Mo. of plants
Sludge application rate mean (mean)
metric tons/ha
0
2
4
8
10
S. sudangrass
132 a*
32 b
14 b
4 b
6 b
Millet
524 a
13 b
23 b
4 b
5 b
Those means followed by the sane letter are not significantly different at
theO.Ol level, using Ouncan's Multiple Range Test.
Table 11-Wheat stand counts on October 15, 1971 for three rows, each 1.83
meters long
No. of plants (mean of 4 reps.]
Sludge application rate Previous fallow Previous millet
metric tons/ha plots plots
0 545 a* 464 a
2 341 a 465 a
4 440 a 427 a
8 478 a 377 a
10 398a 485 a
*Those means followed by the same letter are not significantly different at
the 0.05 level .
29
-------
The harvested weights of the sorghum sudangrass grown on the sludge treated
plots are shown in Table 12. The extremely low values are due to poor ger-
mination and hail damage. The yield variations are more likely to be a re-
sult of differences in germination and emergence than directly due to the
sludge addition on subsequent plant growth. From visual observations, the
individual plants grown in the high sludge application plots were not smaller
than those of the check plots or lower application rates.
Table 12-Yield and nitrogen content of sorghum sudangrass as affected by
sludge application rate.
Application rate
metric tons/ha
Yield
dry weight (kg/ha)
0
25
50
100
125
410 a*
367 a
209 ab
101 b
60 b
1.08 a*
3.08 b
3.23 b
3.30 b
3.43 b
* Mean value of 4 replications. The mean values for %N followed by the same
letter are not significantly different at the .01 level. The mean values
for dry matter yield followed by the same letter are not significantly dif-
ferent at the .05 level. Both sets of data were analyzed using the Duncan's
Multiple Range Test.
The N contents of the harvested sorghum sudangrass are shown in Table 12.
There was nearly a three-fold increase in the nitrogen level of the sorghum
sudangrass grown on the sludge treated plots compared to that of the check
plots. There were no significant differences in N content of the plants
grown on any of the sludge treated plots even though the mean values increased
slightly with increasing sludge applications.
The 1972 wheat yields on the three sets of plots are shown in Table 13. On
the previously fallowed plots there was not a significant difference in yield
between the check plots and any of the sludge application rates except at 125
metric tons/ha. This high rate was the only one at which wheat yields were
significantly lower than the check. The wheat yield picture was different on
the plots that were originally planted to millet. The mean yield values at
the 25 and 50 metric tons/ha ratios were significantly higher than the checks.
The yields on the 25 and 50 metric tons/ha plots were also significantly great-
er than the 100 and 125 metric tons/ha plots. The wheat yield pattern on the
sorghum sudangrass plots is similar to that of the millet plots, but there
were no significant differences; thus, the application of sewage sludge (125
metric tons/ha fallow plots) significantly decreased the yield of wheat com-
30
-------
pared to the check, whereas in two instances (25 and 50 metric tons/ha - mil
let plots), sludge application appreciably increased wheat yields.
Table 13-Effect of sewage sludge addition to Truckton loamy sand on winter
wheat yields, 1972
Dry matter yield (kg/ha)
Application rate Treatment in 1971
metric tons/ha Mi 11et Sorghum sudangrass fallow means
0
25
50
100
125
777 a*
1220 b
1184 b
688 a
320 a
439 a
973 a
902 a
558 a
619 a
826 a
600 ab
428 ab
608 ab
254 b
681
931
838
618
398
* Mean values of 4 replications. Values followed by the same letter are not sig-
nificantly different at the 0.05 level using Duncan's Multiple Range Test.
Chemical analyses of wheat grain grown on the 0, 25 and 100 metric tons/ha
treated plots are shown in Table 14. The mean values for N, K, Ca, Zn, and
Mn increased significantly in the wheat grown on the 25 metric tons/ha plots
compared to the checks. The additional increase at the 100 metric ton/ha
compared to the 25 metric ton/ha rate was not as great. There were no sig-
nificant differences between any of the application rates for P, Mg, Fe, Pb,
and Cd. There was a significant difference in Cu content of the wheat be-
tween the 25 and the 100 metric ton/ha plots. However, in no case was the
content of any of the elements analyzed high enough to be outside the nor-
mal range of concentrations found in plant materials.
It should be pointed out that when these plots were prepared the land was
leveled to facilitate the application of liquid sludge to level bermed plots.
During the operation much of the topsoil was redistributed, thus, some plots
contained little topsoil while others had topsoil added to them. This pro-
bably resulted in considerable variability within the plots. This variabi-
lity in soil most likely contributed to the variability in the data obtained,
decreasing or obscuring statistical significance.
Since there were no duplicates on the filter cake plots, a different type of
statistical analysis had to be run. A polynomial regression analysis indi-
cated a slight decrease in wheat yield with increased filter cake addition
above 454 kilograms per plot, but the differences are not significant (see
Fig. 9). It should be noted that the checks averaged 550-789 kilograms per
hectare, which is considerably lower than any of the filter cake plot yields.
An 8.1 hectare dryland area in a typical wheat field on the Danford-Champlin
31
-------
Table 14-Total elemental composition of wheat grain as influenced by rate of
Metro sewage sludge addition.
Sludge application rates
dry metric tons/ha
Element
°i N
la IN
"/ P
lo "
% K
% Ca
% Mg
ppm Zn
ppm Fe
ppm Cu
ppm Mn
ppm Pb
ppm B
ppm Cd
0
2.06 a*
0.41 a
0.41 a
0.046 a
0.143 a
34.8 a
36.3 a
3.50 a
37.2 a
0.15 a
0.90 a
0.07 a
25
2.89 b
0.51 a
0.49 b
0.073 b
0.149 a
52.5 b
45.9 a
4.46 a
77.0 b
0.14 a
1.31 ab
0.16 a
100
3.10 b
0.45 a
0.52 b
0.076 b
0.156 a
54.2 b
46.5 a
5.96 b
83.6 b
0.08 a
1.46 b
0.19 a
* The mean values in each row followed by the same letter are not
significantly different at the 0.05 level using Duncan's Multiple
Range Test.
2240
Dry Grain 1680
Yield (Kg/ha)
1120
560
(33-2)
(32-2)
(3?-2) (32-1) (32-3) (34-3)
•
•
(£-3)
(Check)
56 T/ha
112 T/ha
i
227 454 681 908 1135 1362 1589 1816
Filter Cake Addition (Kg/plot)
Fig. 9-1972 wheat yield on filter cake plots.
32
-------
Farms at Watkins was treated with about 22,4 metric tons per hectare of fil-
ter cake during the summer of 1971. The cake was incorporated into the soil
by tillage shortly after application. Winter wheat was planted and sampled
on July 14, 1972. Five strips 1.2 x lb,2 meters were taken at random in
the filter cake treated area and a similar sampling from the nonfilter cake
treated area. The wheat yield data are shown in Table 15. There were no
appreciable differences in the mean values of the filter cake treated and
the nontreated strips.
Table 15-Wheat yields from applications of 22.4 metric tons per hectare of
filter cake sludge
Dry matter yield (kg/ha)
Sludge strips Non-sludge strips
Mean
1602.0
1622.5
1613.4
3351.3
2582.0
2042.2
2532.5
2218.16
1720.32
1645.1
1783.8
Mean 1979.9
The field was harvested shortly after, and by a subjective evaluation of Mr.
Jack Danford the yields were not greatly different on the two areas of the
field. The filter cake had no apparent effect on dryland wheat yield.
There were no appreciable differences between the variation of the elements
with soil depth as influenced by cropping situation. Therefore, results are
discussed for all three cropping situations. Data which differ significantly
from the general trends were eliminated for the generalized figures included
in the text.
The first set of soil samples taken shortly after sludge incorporation showed
the normal pH of the topsoil to be about 6.7 and increasing to about pH 7.0
at a depth of 0.76 meters, which is typical of soils in this area (see Fig. 10).
After sludge incorporation the soil pH increased; however, after incubation
through the summer months the pH of the surface soils (0 to 15 centimeters)
decreased compared to the control plots.
Salt concentrations as measured by electrical conductivity show that the salt
concentrations increased with increasing sludge additions (see Fig. 11). Sludge
additions between 25 and 50 metric tons/ha did not cause a salt problem. Ap-
plication rates greater than this caused the conductivity to rise to between 3
and 4 mmho/cni which could possibly be detrimental to sensitive crops.
33
-------
Sampling Time I, Spring 1971
Soil pH
Sampling Time 2, Fall 1971
Soil pH
OUII |/n
-------
The general change in organic matter content of the soil is shown in Fig. 12,
The higher the sludge application rate the higher the organic matter content
of the soil. Fig. 12 demonstrates that there was some organic matter decom-
position during the summer months. Below the 0.3 meter depth there were no
measurable differences in the organic matter content of the plots.
Sampling Time I, Spring 1971
Organic Matter (%)
1.0 2.O 3.0
Soil
Depth
(m)
.30
.61-
.91
1.22-
1.52-
1.83-
2.13-
2.44
Sampling Time 2, Foil 1971
Organic Matter (%)
1.0 2.0 3.0
:heck
100-125 T/ho
-25-50 T/ho
Checl
.30
.61-
.91
Soil
Depth 1.22
(m)
1.52
1.83-
2.13
2.44
100-125 T/ho
25-50 T/ha
Fig. 12-Organic matter content of soil with various rates of sewage sludge
additions.
Nitrate-nitrogen content of the surface soil samples were 2, 4 and 10 times
higher than the control plots for the 25, 50 and 100 metric ton/ha sludge ap-
plication rates, respectively (see Fig.13). The second sampling shows that
the N03-N content had increased markedly in the surface soils and had leached
to a depth of about 2 meters.
Available P remained for the most part in the surface soils with some move-
ment to the 0.4 meter depth (see Fig.14). The bulge at the 1.5 meter depth
is likely an analytical error rather than any movement to this depth. The
surface soil samples that have had sludge applications all show high levels
of available P, but it is doubtful that this could be considered detrimental
to plant growth.
The check plots contained about 120 to 140 ppm of extractable K in the sur-
face soils at the time of the first sampling (see Fig. 15). The intermediate
sludge application rates (25 to 50 metric tons/ha) caused the available K le-
vel to increase to over 200 ppm. Heavy rates (100 to 125 metric tons/ha)
caused the K content to rise to over 350 ppm. After the summer period, the
K distribution had not changed appreciably in the surface soils. Sludge ad-
ditions increased the K level to the 0.45 meter depth; possibly indicating
some downward movement of K.
35
-------
0
Sompling Time I, Spring 1971
NO-jN Content (ppm)
20 40 60
Soil
Depth
(m)
.30
.61
.91
1.22
1.52
1.83-
2.13
2.44
:heck
80
Sampling Time 2, Fall 1971
NO, Content (ppm)
20 40 60
100-125 T/ho
T/ha
T/ho
2.44)
Fig. 13-N03-F
of soil with various rates of sewage sludge additions
o
.30
.61 -
.91
Soil
Depth |.22
(m)
1.52-
1.83-
2.13 •
2.44-
Check
Sampling Time I, Spring 1971
P Content (ppm)
IOO
300
300
—i—
400
Sampling Time 2, Fall 1971
P Content (ppm)
100 200 3OO
'25-50 T/ha
Check
IOO-125 T/ha
400
25-50 T/ha_
100-125 T/ha
Fig. 14-Available P content of soil with various rates of sewage sludge
additions.
36
-------
o-
Soil
Depth
(m)
.30
.61
.91
1.22-
1.52-
1.83-
2.13-
2.44
Sompling Time I, Spring 1971
K Content (ppm)
100 200 300
Sompling Time 2, Foil 1971
K Content (ppm)
400
100
Check
100-125 T/ha
-25-50 T/ho
Soil
Depth
(m)
.30
.6H
.91
1.22-
1.52-
1.83-
2.13-
2.44-
200
i—
300
—i—
400
Check
100-125 T/ho
-25-50 T/ho
Fig. 15-Available K content of soil with various rates of sewage sludge
additions.
Sompling Time I, Spring 1971
Zn Content (ppm)
10 20 30
40
Sompling Time 2, Foil 1971
Zn Content (ppm)
10 20 30
40
0-
.30
.61-
son -9I
Depth
/ \ ' 22
(m)
1.52
1.83
2.13
2.44-
1 1 1 — . •» V-
Xf^ " IOO -125 T/ho .30-
^-25-50 T/ha
.61 •
son -91'
Depth
, . L22
(m)
1.52.
1.83
2.13
2.44
Check 25-50 T/hg •
X^--" 100-125 T/ha
Fig. 16-DTPA extractable Zn content of soil with various rates of
sewage sludge additions.
37
-------
Sampling Time I, Spring 1971
Fe Content (ppm)
10 20 30 40
Sampling Time 2, Fall 1971
Fe Content (ppm)
10 20 30
40
0
.30
.61
.91
Soil
Depth I • 22
(m)
1.52-
1.83-
2.13
2.44
0
Check
100-125 T/ha
.30
.61 •
.91 •
Soil
Depth 1-22
(m)
1.52-
1.83-
2.13
2.44-J
Check
45 - 55 T/ ho
-22 T/ha
Fig. 17-DTPA extractable Fe content of soil with various rates of sewage
sludge additions.
Sompling Time I, Spring 1971
Cu Content (ppm)
246
Sompling Time 2, Fall 1971
Cu Content (ppm)
246
Soil
Depth
(m)
0
.30
.61
.91
1.22-
1.52
1.83-
2.13
2.44
100-125 T/ho
.30
.61
.91
Soil
Depth >• 22
(m)
l.52^
1.83
2.13
2.44J
100-125 T/ho
25-50 T/ha
Fig. 18-DTPA extractable Cu content of soil with various rates of sewage
sludge additions.
38
-------
Sompling Time I, Spring 1971
Mn Content (ppm)
Sompling Time 2, Foil 1971
Mn Content (ppm)
0 20 40 60 80 0
. i J f\ _
o-
.30-
.61 -
Soil "9I
Depth
(m)
1.52
1.83-
2.13
2.44
heckl / ^^^ 100-125 T/ho
k^W5-50T/ho 3°
H .61 '
_ . .91 '
Soil
(m) L22
1.52-
1.83
2.13
2.44
20 40 60 80
, i • '
Check / ^^-^^-^"^00-125 T/ho
/yX^ \-25- 50 T/ho
f
Fig. 19-DTPA estractable Mn content of soil with various rates of sewage
sludge additions.
Bacterial counts were made on surface soil samples taken on November 30, 1971
after harvesting of the crops (see Table 16). There was an appreciable in-
crease in total aerobic bacteria (probably reflects the increased food source
of sludge organic matter), total coliform bacteria and fecal streptococci.
Fecal coliform bacteria were not increased by sludge additions to the soil.
An estimate of the number of fecal coliform bacteria in the original soil-
sludge mixture would be on the order of 1 x 10&; thus, the die off rate for
fecal coliform during the summer months would be somewhere around a thousand
to ten thousand fold.
Infiltration determinations were made on four adjacent millet plots (see Fig.
8) in late July of 1972. Twelve determinations made on the control plots
were considered checks and those on the 125 metric ton/ha of sludge applied
plots were considered as the treated plots. The time to infiltrate 1.27 cen-
timeters, 2.54 centimeters, 5.08 centimeters and 10.16 centimeters of water
were taken as the dependent variables. In addition to the amount of sludge
applied, the moisture content to the 91.44 centimeter depth and the center of
gravity of the moisture to the 91.44 centimeter depth were also considered as
factors affecting infiltration. The infiltration results are displayed in
Fig. 17 and the average values for the infiltrated depths are shown in Table
17.
The scatter in Fig. 20 is typical of measurements made with cylinder^infiltro-
meters. This is due in large measure to the small area samples (45.22 centi-
meter diameter) and the corresponding large edge effects around the cylinder.
These are due primarily to the shattering of the soil when the infiltrometer
is driven into the ground
39
-------
Table 16-Bacterial counts of soil samples taken from fields (fallow and
sorghum sudangrass) treated with sewage sludge
Sludge applied Soil depth
metric tons/ha (cm)
Fallow
0
125
Sorghum
0
0
0
25
25
25
125
125
125
0 -
0 -
sudangrass
0 -
3.2 -
6.3 -
0 -
3.2 -
6.3 -
0 -
3.2 -
6.3 -
6.3
6.3
3.2
6.3
10.1
3.2
6.3
10.1
3.2
6.3
10.1
Total
aerobic
bacteria
3.3 x
24 x
4.0 x
5.8 x
5.6 x
13 x
12 x
16 x
14 x
17 x
4 x
IO6
IO6
IO6
IO6
IO6
IO6
IO6
IO6
IO6
IO6
IO6
Total
col i form
bacteria
2.2 x
6.9 x
1.4 x
.35 x
.24 x
.45 x
2.8 x
4.5 x
30 x
5.3 x
8.5 x
103
IO3
IO3
IO3
IO3
IO3
ioa
IO3
103
103
IO3
Fecal
col i form
bacteria
<1 x 103
<1 x IO3
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
<1 x IO2
Fecal
streptococci
< 1 x
<3.2 x
< 1 x
V 1 X
N 1 X
13 x
28 x
89 x
.8 x
6.3 x
6.9 x
IO2
IO2
IO2
IO2
IO2
IO2
IO2
IO2
IO2
IO2
IO2
Table 17-Average values for infiltration rates on sludge treated soils
Infiltrated depth of
water (cm)
1.27
2.54
5.08
10.16
Time to infiltrate
on control plots
f
- min
1.48
4.66
14.62
46.02
Time to infiltrate
on sludge plots
0.57
2.69
12.76
60.57
40
-------
Infiltration (Acre Feet/Acre)
10
Time, min.
100
°
0
o
0.01
o
O
o
S 8* *•
o 0 &>o .
OD
• Sludge plots
o Non-sludge plots
• •
o
o
o
J L
0.1
1.0
Fig. 20-Infiltration of water into sludge treated and non-sludge treated
soils.
41
-------
From the standpoint of modeling it was found that the effect of sludge appli-
cation is largely overshadowed by other variables, except in the case of the
2 inch water application. The most significant variable found in modeling
each of the water applications is shown in Table 18.
Table 18-Significant variables found in modeling water applications of 1.27,
2.54, 5.03 and 10.16 centimeters.
Depth of infiltrated water
(inches)
Most influential variables measured
1/2
Moisture content, center of gravity of
moisture content
Moisture content, center of gravity of
moisture content, product of moisture
content and center of gravity of moisture
content
Moisture content, center of gravity of
moisture content, sludge or sludge alone
None of variables selected were signifi-
cant
The conclusion to be reached from the infiltration studies is that sludge did
not appear to offer any adverse effect on the infiltration of water into the
soil when measured after cropping.
Summary and Conclusions
Germination and emergence of the sorghum sudangrass and millet were poor on
all plots where sludge had been applied. Subsequent poor growth and two hail
storms prevented the obtaining of useful yield data. The winter wheat exhibi-
ted no germination or emergence inhibition. Wheat yield data showed a ten-
dency toward increased growth on the 25 and 50 metric ton/ha sludge plots, but
these increases were not statistically significant except for the original
millet plots. When the plots were prepared the land was leveled to ensure
level plots for the liquid sludge applications. This leveling caused some of
the sandy topsoil to be removed from some areas and added to others. This re-
sulted in considerable variability within the plots. This variability in soil
most likely contributed to the variability in the data obtained, decreasing
or obscuring statistical significance.
With increasing sludge applications there was an increase in salts, N03-N, P,
K, Cu, Zn, Mn and Fe in the surface soil. Below the top 30 centimeters of
soil only NOs-N accumulated in appreciable quantities above the control levels,
There was a slight indication of increased concentrations of P and K at 30 to
46 centimeter depths.
Microbial counts showed that the sludge plots had an appreciable increase in
42
-------
total aerobic, total coliform and fecal streptococci bacteria, while the fe-
cal coliform bacteria were not greater in the sludge plots than in the con-
trol plots.
Infiltration measurements indicated that infiltration was not significantly
increased or decreased due to sludge application one year after application.
THE EFFECT OF METRO SLUDGE ON GERMINATION AND PLANT GROWTH OF THREE
CROPS IN A GREENHOUSE STUDY
The studies conducted at the Watkins research plots demonstrated germination
inhibition in sorghum sudangrass and millet when the seed was planted soon
after liquid sludge incorporation into the soil. To investigate the effect
of liquid sludge and filter cake on the rate of germination and subsequent
early plant growth, a greenhouse study was conducted at the Elliot carnation
greenhouse adjacent to the Metro plant.
Maten' a1s and Methods
A bulk sample of topsoil from the experimental area at Watkins, Colorado was
obtained for r.iixiny witii cue sewage sludge and filter cake for this study.
Samples of typically produced sewage sludge and filter cake were dried and
prepared for bulk mixing with the soil as shown in Table 19.
Table 19-Rate of sludge applications to Truckton sandy loam soil
Treatment no.
1
2
3
4
5
6
7
8
X
Sludge addition
0
' 1.0
2.0
4.8
2.0
4.8
9.1
1.0
Equivalent dry rStes
in metric tons/ha
0
22.4
44.8
106.7
44.8
106.7
203.6
22.4
Type of Sludge3
filter cakeb)
filter cake
filter cake
driedc^
dried
dried
liquidd)
a) Sludge was SOX anaerobically digested primary sludge and 50% aerobically di-
gested waste activated sludge.
b) Filter cake sludge added to soil at 17% dry weight solids.
Dried sludge was air dried filter cake added to soil.
Liquid sludge added to soil at 52 dry weight solids.
43
-------
The various soil treatments were added to plastic lined cardboard cartons
(1.8 liters) at the rate of 2.17 kilograms per pot. No fertilizer additions
were made; thus, the only nutrients available were from the sludge additions
and the native soil (see Table 9). Water was added to field capacity.
The pots of treated soil were allowed to incubate for 0.5, 1, 3 and 6 months
prior to seeding with wheat, sorghum sudangrass hybrid, or corn. After the
selected incubation periods, 36 wheat, 36 sorghum sudangrass, or 16 corn
seeds were planted by removing the proper depth of soil from the surface of
the incubated pots. Seeds were distributed evenly and covered with soil.
The pots were watered as needed to ensure adequate moisture for germination
and growth.
Counts of the number of emerging seedlings and average plant height were made
after 4 weeks. The pots were then thinned to three corn, four wheat, and
four sorghum sudangrass plants and allowed to grow for the time intervals spe-
cified in Table 20. The plants were then harvested, dried at 60°C and weighed.
Table 20-Soil incubation periods and corresponding planting, thinning and
harvest data
Incubation
period
2 weeks
1 month
3 months
6 months
Date
seeded
4/5
4/19
6/21
9/27
Date
thinned
5/3
5/21
7/12
10/25
Date
harvested
6/20
6/20
9/13
12/12
Growth period
in days
76
62
84
76
Results and_Discussjoii
The number of seeds that germinated and emerged after 1, 3 and 6 month pre-
incubation periods are noted in Tables 21a, 21b and 21c, respectively. Ger-
mination data for the two week incubation period are not included because the
seeds and emerging seedlings were consumed by mice. When this problem became
evident screens were placed over the pots; thus, only the data from the one
month and longer incubation periods are shown here.
Wheat was the least detrimentally affected by sludge additions, with germina-
tion essentially complete after two weeks. Sorghum sudangrass was the most
adversely affected of the crops grown. Even the lowest sludge application
had an adverse effect with the high rate of wet filter cake reducing germin-
ation rates by about two-thirds. Incubation periods longer than one month
had some beneficial effect on sorghum sudangrass, but little effect on wheat
and corn. This evidence would tend to indicate that at least part of the
44
-------
Table 21a-The effect of sewage sludge on germination and emergence of seeds of
three crops. Seeds planted one month after the treatments were
mixed with the soil.
Treatment no.
Wheat
1
2
3
4
5
6
7
6
Sorghum sudangrass
1
2
3
4
5
6
7
8
Corn
1
2
3
4
5
6
7
8
/
20
10
1
0
4
0
0
23
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Days
H
Number of
31
32
24
11
32
15
3
34
21
9
9
2
7
0
0
14
9
11
3
2
1
1
0
16
after
15
seeds
34
35
29
28
34
32
16
34
29
21
10
4
17
4
0
21
16
16
11
6
8
4
4
16
planting*
20
germinated
33
33
28
31
33
34
22
34
30
22
12
5
18
8
0
22
16
16
14
6
16
10
5
16
M
33
34
29
34
34
35
26
34
32
22
12
5
18
9
0
18
16
16
16
12
16
12
5
16
Counts were made on other days; however, the five reported in this table give
the essential trends in germination and emergence.
45
-------
Table 21b-Seeds planted three months after the treatments were mixed with soil
Days after planting*
Treatment no.
Wheat
1
2
3
4
5
6
7
8
Sorghum sudangrass
1
2
3
4
5
6
7
8
Corn
1
2
3
4
5
6
7
8
4_
12
5
4
1
2
4
3
10
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
i Z 19. 11 2T
Number of seeds germinated
29
20
14
4
14
17
5
26
2
0
3
0
2
0
0
2
3
6
2
0
3
1
0
2
32
31
25
9
25
31
8
31
26
8
13
0
4
8
0
17
16
5
10
0
9
8
2
10
34
34
31
15
32
34
17
36
31
14
16
4
16
18
4
21
16
16
16
7
16
15
10
16
34
34
32
19
32
34
26
36
31
16
18
5
19
21
6
24
16
16
16
7
16
15
12
16
34
34
32
22
32
34
33
36
31
16
18
5
20
21
7
25
16
16
16
9
16
15
12
16
* Counts were made on other days; however, the six reported in this table give
the essential trends in germination and emergence.
46
-------
Table 21c-Seeds planted six months after the treatments were mixed with soil
Days after planting*
Treatment no.
Wheat
1
2
3
4
5
6
7
8
Sorghum sudangrass
1
2
3
4
5
6
7
8
Corn
1
2
3
4
5
6
7
8
5.
2
0
0
0
6
1
0
7
7
8
0
0
0
2
0
3
1
0
0
0
0
0
0
1
1 9 14 16
Number oT seeds germinated
11
24
2
2
19
9
4
22
16
8
0
0
4
8
2
11
6
5
0
0
9
3
2
6
17
29
5
3
25
15
12
29
20
11
2
0
8
12
8
15
10
8
1
1
12
6
8
10
20
32
15
4
31
31
16
32
22
12
4
0
13
15
13
18
16
15
4
4
16
13
10
16
22
32
15
6
31
31
16
32
23
12
4
0
14
16
13
18
16
16
5
5
16
14
13
16
22.
25
32
15
7
33
33
23
33
23
12
5
1
15
16
14
18
16
16
6
6
16
15
14
16
* Counts were made on other days; however, the six reported in this table give
the essential trends in germination and emergence.
47
-------
inhibition of germination was due to some volatile component in the sludge,
perhaps ammonia (NH3J. The wet sludge cake was the most inhibitive at one
month, but this inhibitive effect was decreased either by drying prior to
mixing with the soil, or after incubating in the soil for three to six months.
Corn was intermediate in tolerance to germination inhibition, and was only
adversely affected at the high rates of sludge addition.
Variations in germination counts within the controls and treatments were pro-
bably due to the fact that temperature within the greenhouse varied signifi-
cantly and were generally below the optimum germination temperature for corn
and sorghum sudangrass. The experiment was carried out in a carnation green-
house where temperatures were regulated near ]8°C.
Data showing early growth (centimeters of height) of seedlings after germina-
tion and emergence are shown in Table 22. Examination of these data indicates
that the early growth rates were not consistently increased with increases in
pre-incubation periods. As was generally true of the germination data, the
one month and six month plant heights were often lower uian the two week and
three month plant heights. Evidently, the greenhouse environment played a sig-
nificant role in the rate of growth of the seeulings. However, it can be seen
that the height of the crops was appreciably influenced by the rate of sludge
addition, which is most likely a reflection of rate of germination.
Pots were thinned to 3 or 4 average sized plants after approximately 4 weeks
growth and allowed to grow another 2 to 3 months. The data showing the oven-
dried weights of the harvested plant material are shown in Table 23. Since
the growth periods were not the same for all four of the incubation period
treatments (see Table 20 for growth periods) the yield data are not comparable
except for the 76 day growing period for the plants in the 2 week and 6 month
incubation periods. It appears that incubation of the soil-sludge mixtures
for more than 2 weeks for wheat was not helpful. Corn and sorghum sudangrass
showed increased yields with an incubation period of 3 months, however, there
were no further increases in yield at 6 months. In fact, if the 6 month yield
is compared with the 2 week yield for sorghum sudangrass and corn, both having
growth periods of 72 days, it appears doubtful that there was an appreciable
growth response for incubation periods longer than 2 weeks.
Conclusions
Treatments 1 and 8 had the best effects on the three biological parameters
measured in this study with little difference between them. It is apparent
that treatments 4 and 7 were the poorest. Thus, the wet sludge filter cake
had the largest adverse effects on plant growth when compared on an equivalent
weight basis to the dried sludge.
Sorghum sudangrass was the most inhibited by sludge additions, and was affected
to some extent by all sludge treatments. Corn was intermediate in tolerance,
and wheat was the least affected by sludge additions. There appeared to be no
inhibition of germination and emergence of wheat and corn after an incubation
period of 1 month, except for treatment 7 which continued to have inhibitory
effects through 6 months of soil incubation.
48
-------
Table 22-The effect of sewage sludge on early growth (two weeks after planting)
of three crops grown in a greenhouse
Treatment no.
Wheat
'I
2
3
4
5
6
7
8
Sorghum sudangrass
1
2
3
4
5
6
7
8
Corn
1
2
3
4
5
6
7
8
2 weeks
Seed!
8.0*
7.3
7.1
6.9
3.8
2.4
0.6
8.0
1.2
2.8
1.3
1.5
0.3
0.2
**
1.4
3.0
4.3
2.2
4.5
0.7
0.6
0.1
2.2
Incubation
1 month 3
period
months
6 months
ing height in centimeters
10.0
7.8
5.0
3.4
6.2
2.3
0.6
10.0
1.5
1.0
1.0
0.2
0.3
0.1
*+
1.5
4.2
3.2
1.5
0.5
0.6
0.2
-
4.6
16.0
12.6
9.0
9.6
7.4
7.0
4.6
9.6
5.0
1.7
2.3
1.0
1.8
1.8
0.4
2.1
9.4
7.8
6.4
3.0
0.8
5.3
2.7
8.6
10.0
10.1
6.6
5.0
7.0
8.0
8.0
11.2
5.1
5.7
2.8
3.2
7.0
4.0
4.6
7.4
4.4
3.5
1.3
0.7
2.5
2.5
2.1
6.0
* Data are mean values of 5 replicates.
** No germination.
49
-------
Table 23-The effect of sewage sludge on oven dry weight of three crops grown
in a greenhouse for 2 to 3 months
Treatment no.
Wheat
1
2
3
4
5
6
7
8
Sorghum sudangrass
1
2
3
4
5
6
7
8
Corn
1
2
3
4
5
6
7
8
2 weeks
1.41
3.36
2.36
2.22
2.35
2.49
0.67
3.38
0.29
0.21
0.12
0.07
0.06
0.12
0.06
2.91
0.93
2.21
0.37
0.57
0.32
0.07
0.64
2.81
Incubation period
1 month 3 months
Yield
0.47
1.68
0.55
0.17
0.89
0.13
0.14
1.12
1.43
0.92
0.39
0.06
0.21
0.05
*
1.06
1.40
1.29
0.75
0.80
0.71
0.40
0.12
2.00
(grams/pot)
0.67
0.99
2.57
1.75
1.30
0.99
1.15
1.69
0.79
1.31
1.78
0.71
1.50
1.58
0.79
2.30
2.12.
2.48
2.14
1.53
2.58
1.95
0.82
3.16
6 months
1.46
0.90
0.81
0.93
0.86
0.70
0.32
1.05
1.22
0.31
0.58
0.14
0.31
0.40
0.06
0.95
2.35
2.16
0.69
0.57
1.25
0.55
*
*
2.46
* No plants harvested.
50
-------
The dried sludge had less inhibition than equivalent weights of wet filter
cake on emergence and subsequent early plant growth.
Ambient temperatures of the greenhouse used for this study were too low for
adequate germination and growth of sorghum sudangrass, plus the loss of seeds
and some plants to hungry mice made interpretation of these data difficult.
It appears, however, that the effects of sewage sludge additions were more in-
hibitive to sorghum sudangrass germination and emergence than to corn or wheat.
SLUDGE AIR DRYING PROJECT
If liquid sludge is transported from the treatment plant by conventional truck
transport, energy requirements are extremely high and the cost of haul becomes
rapidly prohibitive with increasing distances from the treatment plant. While
removal of some of this water by vacuum filtration reduces hauling costs, me
total costs are still extremely high.
Metro has been investigating pipeline transport of liquid anaerobically di-
gested sewage sludge to a remote area where the sludge could be air dried and
subsequently utilized as an agricultural product. This metnod would not only
avoid expensive haul and vacuum filtration costs, but would also provide a val-
uable agricultural product.
A research project examined the possibilities of drying liquid sludge in
shallow, earthen drying basins. Parameters measured were water loss through
soil percolation and/or evaporation, nitrogen losses and the development of
odors or undesirable vectors, i.e. flies or rodents.
Materials and Methods
Five drying basins were built at the CSU Agricultural Experiment Farm at Fort
Collins. The basin dimensions were 7.6 centimeters x 9.14 meters x 1.2 meters
in depth. Anaerobically digested liquid sludge (approximately 5%) from the
East Drake Wastewater Treatment Plant in Fort Collins was added to the basins
on August 7, 1973 to depths of 25.4, 50.8, 76.2 and 101.6 centimeters (Table
24). The basins did not have underdrains, and basin E was lined with plastic
to prevent water losses due to percolation. Basin G was filled with 101.6
centimeters of anaerobically digested liquid sludge on January 16, 1974 to de-
termine drying rates and nitrogen losses during winter months.
Water loss was determined daily by measuring the level of the liquid sludge in
the drying basins. Percent TS were determined weekly. Determinations of TKN,
NH4-N and N03-N were made weekly. Zinc, Cu, Mn and Fe are reported as DTPA
extractable metals. Available P was determined by extraction with ascorbic
acid. Potassium was analyzed by extracting with normal NH/jOAC.
Results and Discussion
Basin A to which 25.4 centimeters of sludge were applied, dried from about 5«
51
-------
TS to about 50% to 60% solids in a 1 month period (Table 25). Basin B to
which 50,8 centimeters of sludge were applied, dried to 40% TS in a 4 month
period. None of the other basins dried during the duration of the experi-
ment (10 months). It is interesting to compare basin B (unlined) with ba-
sin E (lined). Both basins received 50.8 centimeters of sludge, however,
the latter basin showed more dilute solids concentration in January 1974
than when it was originally loaded in August 1973. This demonstrates that
most of the water loss was due to percolation into the soil rather than
evaporative losses, and that during the winter months precipitation exceed-
ed evaporative losses.
Table 24-Initial depth of liquid sludge
Basin Liquid sludge depth (cm)
A
B
C
D
E*
G
25.4
50.8
76.2
101.6
50.8
101.6
*
from percolation.
Table 25-Change in percent total solids content of drying basin with time
Sampling Date
8773 T77T
Basin % Total sol ids
A
B
C
D
E
4.6
4.6
4.2
4.2
4.2
61.7
40.3
13.9
7.5
3.3
The Fort Collins Agricultural Experiment Station has a permanent meterological
station where pan evaporation and precipitation are accurately measured. Data
from this station indicated that:
A) Net evaporation (evaporation minus precipitation) occurred during the
months of June through December.
52
-------
B) Negative evaporation (excess of precipitation over evaporation)
occurred during January through May.
C) Total precipitation (rain and snowfall) averaged 2.8 centimeters
per month for a total of 34.0 centimeters between October 1972 and
September 1973,
D) Gross evaporation totaled 92.7 centimeters.
E) Net evaporation totaled 08.7 centimeters.
F) Precipitation during the 7 driest months (June through December) to-
taled 20.3 centimeters.
G) Gross evaporation during the 7 driest months (June through December)
totaled 58.4 centimeters.
H) Net evaporation during the 7 driest months totaled od.l centimeters.
By comparing these data with a desired sludge cake end product of at least
40% TS for subsequent stockpiling, it is theoretically possible to establish
the optimal sludge loadings for any particular season. Table 26 summarizes
the net evaporation requirements over a 12 month and 7 month period at load-
ing rates between 15.24 and UI.92 centimeters per application. Based on
the 1973 through 1974 meteorological data there is a net evaporative rate of
58.7 centimeters per year. Then the maximum liquid sludge depth possible for
a 40% TS sludge cake equals 6b.O centimeters. The 7 driest months of the year
(June-December) have a net evaporative rate of 38.1 centimeters; thus, the
maximum liquid sludge load possible for obtaining a 40% TS sludge equals 42.3
centimeters.
It should be pointed out that these are hypothetical figures based on evapora-
tion of pan water. Water obtained in partially dried sludge will be under ca-
pillary forces; therefore, decreasing the net evaporative effect.
One of the problems associated with drying the sludge was the development of
a thin, dried sludge crust on the basins' surfaces. The hydraulic conducti-
vity of this dried crust is severely reduced, preventing the capillary move-
ment of water to the surface from the saturated sludge below. The effect of
this crust is evident when the TS content of basin B is compared with basin E.
Basin E was lined with plastic; therefore, all water losses were from evapora-
tive losses. Because of this crust development basin E did not dry. Basin B
lost water through percolation rather than evaporation. Another approach be-
ing studied is the addition of thin layers of liquid sludge (0.6 centimeters
per application). In this way it is hoped that there will be no significant
crust development covering a pool of liquid sludge.
The odor level was not usually significant except for a brief period. The
most intensive odors were encountered after the spring thaw of frozen sludge
in the drying basins. There were neither odor nor other nuisance complaints
by any of the neighbors. Many small flies or gnats accumulated over the ba-
sins during the last half of August, but did not assume nuisance proportions.
53
-------
Table 26-Net evaporation required (centimeters per year) at various sludge
loading rates
Sludge loading in
Variables
Water load @ 4% TS (cm)
Precipitation 1973-1974 (cm/yr)
Total water load (cm/yr)
Final sludge volume required
G> 40% TS (cm)
Gross evaporation required (cm/yr)
Precipitation June- December (cm/-
season)
Total water load (cm/season)
Final sludge volume (cm) required
(3 40% TS
Gross evaporation required (cm/-
season)
15.24
14.7
34.0
48.7
1.5
47.2
20.3
35.1
1.5
33.5
30.5
29.2
34.0
63.2
3.0
60.2
20.3
49.5
3.0
46.5
61.0
58.4
34.0
92.4
6.1.
86.4
20.3
78.7
6.1
72.6
cm/year
91.4
87.9
34.0
121.9
9.1
112.8
20.3
108.2
9.1
99.1
121.9
117.1
34.0
151.1
12.2
144.0
20.3
137.4
12.2
125.2
Chemical data indicated that the sludge lost considerable quantities of ex-
tractable NH4-N (from about 5,000 ppm to 2,000-3,000 ppm) but little NOs-N
accumulated in the sludge. Apparently, NHj was volatilized or nitrified,
and the NOs was denitrified below the surface.
On January 15, 1974 101.6 centimeters of anaerobically digested sludge (ap-
proximately 71,000 liters) from the Fort Collins Sewage Treatment Plant were
loaded into a lined drying basin (designated basin G). A sampling program
was designed to obtain weekly samples from three locations at three different
depths for nitrogen analysis. Table 27a summarizes the nitrogen concentra-
tions while Table 27b summarizes the nitrogen concentration as a percent of
the total solids concentration of the three stratified samples.
Within 4 weeks of the initial loading approximately 38% of the TKN was lost.
Most of this loss occurred in the bottom and middle layers of the stratified
basin, and changed little thereafter. Within 6 weeks of the initial loading,
approximately 75% of the NH4-N had been lost and again most of the loss occur-
red in the bottom and middle layers. During the sixth week, solids from the
bottom layer floated to the top stratum which tended to raise the N concentra-
tions of the top and middle layers.
The variations in other chemical determinations followed no definite pattern,
neither increasing nor decreasing with time, and are shown in Table 28.
54
-------
Table 27a-Nitrogen concentration of 3 layers of liquid sludge in drying basins'
Date sampled
1/23/74
2/5
2/12
2/19
2/16
3/5
bottom
2,850
1,300
780
740
725
700
NH4-N
middle
3,230
1,340
•760
750
700
750
top
590
1,000
660
675
450
700
bottom
4,500
2,980
3,250
2,860
3,090
2,640
mg/1
TKN
middle
4,710
2,720
2,910
3,040
2,150
2,690
top
644
664
716
636
448
1 ,650.
bottom
0.50
0.05
2.20
0.80
0.20
0.65
N03-N
middle
1.05
0.20
2.35
0.50
0.40
0.65
top
0.45
0.25
0.01
0.45
0.10
1.65
Table 27b-Nitrogen concentration as a percent of the total solids concentration
of the three stratified samples
Date sampled
1/23/74
2/5
2/12
2/19
2/26
3/5
bottom
6
2
1
1
1
1
.2
.2
.3
.3
.3
.2
NH4-N
middle
9.0
2.7
1.4
1.3
1.2
1.3
top
11.3
14.3
11.0
11.3
10.0
1.8
bottom
9.8
5.2
5.3
5.2
5.6
4.4
X
TKN
middle
13.1
5.6
5.2
3.2
3.6
4.6
N03-N
top bottom middle
12
9
11
10
9
4
.4
.5
.9
.6
.8
.1
N*
N
N
N
N
N
N
N
N
N
N
N
top
N
N
N
N
N
N
* N mean negligible.
55
-------
Table 28-Range in various chemical constituents of liquid sludge contained in
drying basins
Chemical constituent
* Volatile solids
Conductivity umhos/cm
PH
P* (ppm)
K** (ppm)
Zn*** (ppm)
Cu (ppm)
Fe (ppm)
Mn (ppm)
42
4.5
7.2
650
690
285
34
150
4.8
Range
- 70
- 7.1
- 8.5
- >1000
- >1000
- 505
- >50
- 310
- 11.4
* Sodium bicarbonate extractable P.
** Ammonium acetate extractable K.
*** DTPA extractable Zn, Cu, Fe and Mn.
Conclusions^
This study indicated that earthen drying basins with more than 50.8 centi-
meters of sludge will not dry rapidly enough to allow yearly removal of dried
sludge. Comparisons of lined and unlined basins demonstrated that most of
the water loss was through soil percolation and not evaporation. The forma-
tion of a thin dried sludge crust prevented evaporation from taking place at
the sludge surface. If this sludge crust could be constantly broken up and
reincorporated into the wet sludge or prevented from forming through appli-
cations of thin layers of liquid sludge, it would be theoretically possible
to dry as much as 43.2 centimeters of liquid sludge per year. During the
drying process, about 45% of the total N content is lost through leaching,
volatilization or denitrification.
56
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FUTURE AGRICULTURAL RESEARCH AND DEVELOPMENT PROJECTS
In 1975, a comprehensive $418,000 researcn program consisting of 10 projects
was approved by the Metro Board of Directors. This agricultural research
program was designed to obtain additional information on various aspects of
sludge recycling to land, and to answer some of the questions raised in the
Environmental Protection Agency Technical Bulletin No. 430/9-75 titled "Ac-
ceptable Methods for the Utilization or Disposal of Sludges". The projects
included:
1. Investigation of drying basin optimization.
2. Sludge characterization to define chemical and biological constituents
of Metro sludge.
3. Investigation of detention times and otner conditions required to re-
duce to acceptable levels viruses and other potential pathogens.
4. Nitrogen management: to enhance or diminish nitrogen concentration in
sludge depending on intended use.
5. Greenhouse and crop rotation study.
6. Heavy metals monitoring.
7. Heavy metals monitoring of soil receiving cumulative sludge loadings.
8. Subsurface injection of liquid sludge.
9. Mine tailing reclamation.
10. Investigation of heavy metals as it effects the food chain from sludge
to the tissues of animals grazing on vegetation grown on a sludge-soil
mixture.
Metro is also working with the U.S. Geological Service and the Colorado State
Geologist Office to investigate the effect of heavy loadings of sewage sludge
conditioned with chemicals on ground water at the Lowry Bombing Range.
A summary of project objectives and scope of work follows.
57
-------
DRYING BASIN PROJECT
Objective
To obtain information on a continuous loading basis required for development
of a relatively problem-free operations scheme to manage 600 acres of drying
basins at the proposed sludge drying and distribution site.
Scope of Work
1. Anaerobically digested liquid sludge (primary and mixed primary plus se-
condary) are being added to earthen drying basins to determine optimum
loading rates and drying times.
2. The loading rates are intended to simulate fullscale loading rates tu ba-
sins at a sludge drying and distribution center.
3. Four separate drying basins, each 0.1 hectares, are being utilized. The
basins are unlined and without underdrains.
4. Acceleration of drying rate of 101.6 centimeters of sludge is being inves-
tigated by.
A) Decanting supernatant liquor (less than 1.0% total solids).
B) Mechanical agitation using surface drag.
5. Special emphasis will be placed on evaluating seasonal effects as they re-
late to hindrance of drying with each successive liquid sludge loading to
previously dried sludge.
6. Information obtained from successive loadings will be used to determine
strategy for dried sludge removal and storage.
7. The practical problems involved in removing thin layers of dried sludge
mixed with soil will be investigated.
8. The Northern Colorado Research Demonstration Center (NCRDC) at Greeley,
Colorado is the site for this investigation. The research farm provides
an excellent demonstration to the farm community of the benefits of this
project.
9. Each basin is being monitored for:
A) Water loss by percolation.
B) Quality of the water percolating through the soil profile.
C) Nitrogen changes in the sludge as a function of drying time.
D) Odors and vectors.
58
-------
E) Change in soil permeability with successive applications of liquid
siudge.
10. The Fort Collins treatment plant is the source of liquid anaerobically
digested primary plus secondary sludge, while the Denver North Side
Treatment Plant is the source of anaerobically digested primary sludge.
11. The air dried sludge will be cured in a stockpile for several months.
The effect of drying time on pathogen reduction will also be monitored.
SLUDGE CHARACTERIZATION
Objective
1. To obtain data concerning concentrations and seasonal variability of
those parameters (heavy metals, nutrients, etc.) used by regulatory
agencies to establish guidelines for land application of stabilized
sludge.
Scope of Work
1. Metro laboratory is analyzing monthly composite sludge samples for ferti-
lizer elements (TKN, NH^, total P and total K) and heavy metals (total Zn,
Cu, Ni, Cd, Pb, Cr).
PATHOGEN STUDY
Objective
1. To determine relative concentrations and variability in the anaerobically
digested sludge of certain viral and parasitic organisms having public
health significance.
2. To determine the survival rate of the pathogens in the soil-sludge mix-
ture. Particular emphasis will be placed on the minimum detention time
required between sludge application to land and the growth of crops dest-
ined for human consumption.
Scope of Work
1. The Biological Waste Management and Soil Nitrogen Laboratory of the Agri-
cultural Research Service at Beltsville, Maryland will provide the analy-
tical services and research direction for this study.
2. Survival rates of endemic salmonellae and ascaris ova in digested sludge
as it is dried and stockpiled will be determined to estimate the air dry-
ing or storage time needed to eliminate these organisms.
59
-------
3. Sewage sludge at the treatment plant will be seeded with f2 bacteriophage.
The survival of f2 bacteriophage, which closely resembles the enteroviru-
ses (poliovirus, coxsackievirus, echovirus and reovirus) physiologically,
will be examined to estimate the survival rates of other viruses which
are difficult to impossible to identify in sludge.
4. The liquid sludge will be applied to the sludge drying basins at Greeley,
Colorado. Samples of the sludge will be collected every 2 weeks for path-
ogen and virus analysis.
5. Sampling will continue long enough to establish the survival times of the
organisms.
NITROGEN MANAGEMENT PROJECT
Objectives
1. To prevent nitrate pollution of ground waters.
2. To maintain the nitrogen fertilizer value in the sludge that is to be
marketed.
Scope of Work
1. The staff of the Department of Agronomy at CSU will conduct the laboratory
phase of this project during the first year.
2. Upon successful completion of the laboratory phase of this study, a second
phase field experiment may be recommended to verify on a large scale re-
sults obtained from the lab study.
15
3. A laboratory bench anaerobic sewage sludge digester has been fed N en-
riched ammonia in order to incorporate the labeled nitrogen isotope into
both the organic and inorganic nitrogen compounds of the digested sludge.
4. The N enriched sludge will be added at various loading rates to soil.
After suitable detention periods, the soil-sludge mixture will be quanti-
tatively analyzed for NH/;, N03, N20, NO and N2 by mass spectrometry.
This analysis will determine the rate of denitrification occurring in
the soil-sludge mixture.
5. Gas samples will be taken from enclosed incubation vessels for determining
C02, CH4, NO, N20 and N2 gas production. A comparison of gas chromato-
graphy and mass spectrometry results will enable determination of kinetics
of mineralization, nitrification and subsequent denitrification of organic
nitrogen forms.
60
-------
GREENHOUSE AND CROP ROTATION STUDY
Objecti ves
1. To determine the influence of anaerobical ly digested sludge at various
loading rates on germination, growth and yields of crops grown in Colo-
rado.
2. To apply information obtained from greenhouse tests for validation in the
field under varying crop rotation schemes typical of farm practice in Co-
lorado.
3. To determine the extent to which anaerobical ly digested sludge may be sub
stituted (in whole or in part) for other types of commercial or organic
fertilizers as presently used by the farm community,
ofWork
4.
The greenhouse portion of this study will be conducted during two seasons,
namely:
A) Cold weather germination (15.5°C j^2°).
B) Wan.i weather yermiiiacion (24°C^2°).
'
-------
HEAVY METALS UPTAKE
Objectives
1. To determine the uptake of heavy metals (Zn, Cu, Ni, Cd, Cr and Pb) into
crops commonly grown in Colorado.
2. To determine the extent to which heavy metals become more available or
less available to crops after sludge application to soil.
Scope of Work
1. Two rates of sludge (336 and 670 dry metric tons/hectare) have been added
to experimental plots at the NCRDC at Greeley, Colorado. Total DTPA and
water extractable soil metals are being correlated with plant uptake and
possible yield depression.
2. Metal salts equivalent to 336 and 670 metric tons/hectare have been added
to additional plots to compare availability of sludge born metals to metals
in soils without organic matter additions in relation to plant uptake.
HEAVY METALS MONITORING PROJECT
Qbjecti ves
1. To determine the long-termcumulative effects of repeated applications of
sludge on buildup of toxic metals in soil or plant material at the Watkins
research site.
Scope of Work
1. The 0.8 hectare site consists of 72 plots. Thirteen of the plots have
never received sludge and are used for baseline data comparisons. Loadings
of sludge between 20 and 200 dry metric tons per hectare were applied dur-
mg the first year (1971) to 59 plots. The sludge was subsequently incor-
porated into the soil by discing and plowing.
During the second year (1972) liquid sludge loadings between 20 and 43 dry
metric tons per hectare were applied by subsurface injection to 32 of the
59 plots that received sludge in 1971.
During the third year (1973) no sludge was applied to any of the 72 plots.
During the fourth year (1974) liquid sludge was applied by subsurface in-
jection to 36 of the original 59 plots receiving sludge in 1971 at loadings
between 11.2 and 22.4 dry metric tons per hectare.
2. The Watkins research site monitoring will be continued for another 2 years
until the full scale drying distribution site is in operation. The deci-
sion to phase out the Watkins site will be determined by the analytical re-
62
-------
suits obtained during this perioci,
3. Winter wheat will be planted annually on all of the '12 test plots. Sup-
plemental irrigation will be provided as necessary to ensure germination
and growth despite fluctuations in precipitation.
SUBSURFACE INJECTION PROJECT
Objectives
1. To develop backup technology to the air drying system capable of year
around handling of anticipated sludge producuon at the full scale reuse
site. Particular emphasis will be placed upon injection into frozen soils.
2. To demonstrate the technical and economic advantages of subsurface injec-
tion for liquid nutrient application and crop growth.
Scope of Work
1. The duration of this project is anticipated to be 2 years (1976-1977).
2. Metro will purchase or lease existing injection equipment for both shallow
and deep (0.3 to 1 meter) injection. This equipment will be modified as
required to ensure frozen ground capability, uniformity of sludge distri-
bution and minimizing power requirements for either beneficial recycle or
disposal modes of operation.
3. The nearest recommended injection site available is at the LBR. Eleven
hectares of land which has never received sludge will be used for this pur-
pose.
4. The liquid sludge will be transported from the central plant to Lowry by
means of a 6,000 gallon tank truck whicn will then be connected to the
subsurface injection device by a hose. The subsurface injector will be
pulled by a tractor.
5. Effects of subsurface injected liquid sludge on yield will be evaluated for
native pasture land and winter wheat.
6. Soils and foilage will be analyzed for nutrient and heavy metals content.
MINE TAILING RECLAMATION PROJECT
Objectives
1. To demonstrate the beneficial effect of applying anaerobically digested
sludge for reclamation of rock and mine tailings in forested mountain areas
of Colorado.
63
-------
Scope of Work
1. The site being investigated is located at the base of Berthoud Pass at
the recently abandoned Urad molybdenum mine. Approximately 100 hectares
of mine tailing wasteland will require reclamation over the next few years.
2. During 1975, approximately 12 hectares of tailings received a mixture of
sludge and wood shavings. During 1976-1978 20 hectares per year will be
reclaimed requiring approximately 2.240 dry metric tons per year of sludge
from Metro. Growth response and environmental factors will be evaluated.
ANIMAL UPTAKE PROJECT
Objectives
1. To determine whether and to what extent contamination of tissues in cattle
grazing sludge applied land has occurred which could represent a hazard to
human health.
Scope of Work
1. Representative mature beef cattle from the LBR sludge recycle site and
from a control herd have been slaughtered. Tissue analysis of liver, kid-
ney, muscle, blood, bone, fat and brain is presently being analyzed for
heavy metals and toxic organics.
2. An extensive survey of sludge, soil and vegetation at the LBR and a control
site is presently underway. Samples are being analyzed for the same chemi-
cal constituents being determined in the animal tissues.
3. Beef cattle similar to those at the LBR have been fed Metro Denver sewage
sludge as a percentage of their diet to determine the effect of direct in-
gestion of larger amounts of sewage sludge on edible animal tissues.
GROUND WATER QUALITY AT THE LOWRY BOMBING RANGE
Objectives
1. To investigate the effects that sludge disposal at the LBR has had on
ground water quality.
Scope of Work
1. Determine the location and extent of alluvial aquifers, direction of ground
water movement in the shallowest bedrock aquifer. This is being accomplished
by drilling some 60 wells at various depths in and around the sludge recycle
s i te.
64
-------
2. Quality of ground water upgradient and downgradient from the recycle site
is being monitored for pathogens, alkalinity, sulfates, chlorides, phos-
phates, nitrogen, COD, organic carbon, dissolved solids, hardness and me-
tals (Na, K, Ca, Zn, Fe, Pb, Cr, Cu, Ni, Mn, Cd).
65
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SUMMARY AND CONCLUSIONS
Processing and ultimate disposal of wastewater sludge is one of the most
costly unit processes within any sewage treatment plant. Since 1969 Metro
nas been examining methods of jiudge disposal which are economical and en-
vironmentally safe. Prior to 1969, all of the sludge produced by Metro was
either flash dried, incinerated, or lagooned. The dried material was used
as a fertilizer on city parks, wnile the incinerated material was landfilled.
However, due to continuous mechanical and air pollution problems the flash
dryer-incinerator units were permanently shut down in August of 1971.
Since 1971 the only mode of sludge cisposal used by ,'ietro has been land ap-
plication. A number of different disposal procedures have been tried over
the intervening years.
During 19b9 and ly/U the VJLJU,,, filter cake sludge, which could not be pro-
cessed by the FDI units, was transported by truck to the LBR. Two methods
of incorporation were utilized, one for dry weather and tne second for wet
weather, ury weather operations consisted of tailgating the sludge directly
from the transport vehicle onto the soil surface. The sludge was then thinly
spread over the surface with a front mounted blade on a dozer. The sludge
was allowed to dry for 14 hours and then rototilled in. This operation was
not always satisfactory because large rocks, dense vegetation, or wet soil
would clog or render the rototiller inoperable.
During wet weather, or when the ground was frozen, sludge was mixed directly
into the soil using a front mounted blade on a dozer. A satisfactory mix
was accomplished when approximately 5 parts of soil were mixed with 1 part
of sludge. However, this operation was not satisfactory due to the economics
of a '^\ hour per day operation and its inherent difficulty.
Because of these problems, several changes in sludge application methodology
were adopted. At the LBR site a ramp was constructed which allowed the trans-
port vehicles to load sludge directly into farm manure spreaders. The sludge
was then spread onto native pasture land at the rate of about 6.7 metric tons
per hectare. After the sludge had dried, about a half hour, a spiked tooth
harrow was used to break any large clumps of sludge into fine particles.
This method proved satisfactory for one year, however, during the late spring
of 1972 when the area had dried, small smoldering fires started in the areas
which had received many consecutive sludge applications, a result of careless
smokers and heavy equipment operating in the area. These fires proved diffi-
cult to extinguish, particularly in high winds. Other problems arose when
the contractor experienced difficulty with access to the field. As a result,
large quantities of vacuum filter cake were stockpiled to a depth of about
] .2 meters in a depression. Shortly thereafter snowstorms covered the stock-
66
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piled filter cake. As the snow began to melt, the waste activated and raw
primary sludge began to decompose creating odor nuisances to residents living
adjacent to the area.
Because of the fire and odor nuisances a new method of land application was
started in June of 1972. The sludge was spread 5 to 8 centimeters in depth
and then plowed under within 6 hours of application. Crops such as wheat,
oats or sudangrass were planted to reduce soil erosion, and to provide forage
for the cattle that continuously grazed the land. This method has been pro-
viding satisfactory control of odor and fire problems since 1972.
Special modifications were adopted during winter operations when the soil is
frozen and cannot be plowed. Since 1973 an inclement weather site has been
prepared in advance by bench and terracing the area. Inclement weather opera-
tions generally take place during December, January and February, depending
upon the severity of the winter. During the relatively mild, dry winter of
1974-1975 the inclement weather site was required for only 30 uays ouring
January and February.
Vacuum filter cake sludge disposed of at the LBR is a mixture of raw primary,
waste activated and anaerobically digested primary sludge. Continuous sludge
loadings since 1969 have increased the \-\ content of the soil to excessive
levels beyond any capacity for cr^p removal. However, this may not pose a
serious threat to ground water quality due to the fact that rainfall is limi-
ted and the potable ground water is protected for the most part by impervious
stratum within the regolith.
Sludge additions have increased the K, P, salt and organic matter content of
the LBR soils, but not to levels that could be considered excessive or out of
the normal for agricultural soils in this area. The heavy metal content has
increased significantly, whether this has been detrimental to crop growth is
unknown. However, it is doubtful since tissue analysis of plant samples has
not shown levels that would be considered out of the normal elemental compo-
sition range for plant materials.
By 1971 it became apparent that land application of wastewater sludge was not
going to be a temporary expedient, but rather a long term necessity. There-
fore, a number of studies were entered into to evaluate the effects of sludge
on environmental concerns and crop response.
A field experiment was set up at Watkins, Colorado to evaluate the effects
of various sludge loadings to crop germination and subsequent growth. Re-
sults indicated that there was a severe inhibition of germination when mil-
let or sorghum sudangrass were planted immediately after sludge incorporation.
However, this inhibition was eliminated when the sludge was allowed to incu-
bate in the soil for two months. Wheat yield data showed increased yields
with application rates of 25 and 5(J dry metric tons per hectare.
Microbial counts taken 6 months after sludge incorporation demonstrated that
there were no differences in fecal coliform bacteria between the sludged plots
and the control plots.
67
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The studies conducted at Watkins led to a greenhouse investigation in which
a number of soil sludge mixtures were utilized to evaluate the effects of
various incubation periods on germination and plant growth, Results demon-
strated that sorghum sudangrass was inhibited the most by sludge additions,
while corn was intermediate in tolerance, and wheat was the least affected
of the three crops tested. There appeared to be no inhibition of germination
and emergence of wheat and corn after a soil sludge incubation period of 1
month. Of the sludge types used, dried sludge had the fewest adverse effects
on germination.
Metro has been investigating the possibilities of air drying liquid anaero-
bically digested sewage sludge in shallow, earthen drying basins, Data col-
lected from experimental drying basins demonstrated that more than one-half
of the N content of the sludge is lost during the air drying process. Com-
parisons of plastic lined and unlined basins demonstrated that most of the
water is lost through soil percolation and not evaporation.
It is important to realize that the recycling of organic matter is not a
new process, but one that has been occurring for eons, since the beginning
of life itself and is essential for its very maintenance. Oryanic matter
represents a stockpile of energy, one that should not be wasted. With the
realization that fossil fuels (recycled organic matter) are coming in short
supply, it becomes evident that ^ waste any source of energy is self defeat-
ing. It is interesting to note that the word waste is often applied to human
and animal excreta when in a biological sense it is not a waste. In fact,
the only justification for the term "waste" is that a potential source of
energy has been wasted.
Unfortunately, there are problems associated with the recycling of sewage
sludge. Much of our sewage is not derived from garbage or fecal material,
but is the product of industrial waste. Modern society tends to centralize
and concentrate industry, which is reflected in the wastewater treatment
plant. Thus, metals or exotic organic compounds such as pesticides which
are products or by-products of industry turn up in sewage sludge. In addi-
tion to these elements and compounds there is a disease hazard. The prob-
lems in dealing with these elements, compounds and biological agents become
particularly acute when sludge is to be recycled into agriculture and the
food chain.
If sewage sludge is to be utilized as an agricultural resource, the authors
of this report feel that there are a number of areas which will require future
research efforts. These include public health aspects, plant response and
food chain effects from heavy metals, the true fertilizer value of sewage
sludge as measured by crop response, and particularly, public awareness or
acceptance of sludge as a resource.
Under the heading of public health aspects fall a number of issues or problems.
The most immediate is whether or not utilization of sewage sludge on agricul-
tural land represents a health hazard. Pathogens are known to survive the
sewage treatment process, but the threat to public health has not been ade-
quately evaluated. Research efforts are needed to determine the survival rates
of enteric pathogens (parasites, bacteria and viruses).
68
-------
Since there is the possibility that cattle may ingest quantities of sludge,
i.e soil or from dust on forages, the health effects on livestock or humans
consuming the livestock should be evaluated.
Another public health aspect would have to include possible food chain effects
of heavy metals on crops, animals, and humans. Little is known about the tol-
erance or uptake rates of plant species and varieties under different soil,
climate and management practices. Metals that should be studied include As,
B, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn because of their potential toxicity to
plants or hazard to livestock and humans.
If sewage sludge is to be handled as a resource, specific data evaluating its
effects on crop yield and quality should be made available to the potential
user. Responses of various crops should be evaluated for different manage-
ment practices which would include loading rates, soil pH levels, climate,
irrigation or water relationships, timing of application, methods of incor-
poration different forms of sewage sludge (i.e. dried, liquid, dewatered),
and rates of nutrient removal or availability.
And finally, the public will have to be educated and made aware of the econo-
mical and ecological advantages of recycling sewage sludge in order to counter
existing cultural prejudices against wastewater sludge.
69
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APPENDIX A
Table 29-Analysis of Lowry Bombing Range soils sampled spring of 1972
Site no.
U
IB
1C
2A
28
*C
3A
38
3C
Soil
depth
Inches
0-6
6-12
12 - 24
«4 - 36
36+
0 - 6
t> - 12
12 - 24
24 - 36
0-6
6-12
12 - 24
24 - 36
0-6
6 - 1Z
12 - 24
24 - 36
36+
0-6
6-12
12 - 24
24-36
0 - 6
6-12
12 - 24
24 - 36
0-6
6-12
12 - 24
0-6
6 - 12
12 - 24
24-36
0-6
6-12
12- 24
24-36
PH
saturated
paste
7.5
7.9
8.2
6.3
S.I
7.9
8.1
6.2
8.1
7.0
7.0
e.o
8.3
7.5
7.7
8.0
8.3
8.4
7.3
7.S
6.3
8.5
6.9
7.0
8.2
6.0
7.3
7.2
6.1
6.6
7.3
8.0
7.
O.u
0.6
5.4
7.3
3.;>
0.6
1.5
0.9
O.b
3.0
O.b
1.4
O.b
1.*
O.b
0.4
0.4
NaiiCOa
P
13.0
2.0
2.0
4.8
6.5
11.3
2.0
2.C
2.3
18.3
12.5
2.8
7.0
49.3
7. 0
5.3
4.C
6.3
35. »
6.5
6.0
5.3
42.5
21.3
46.b
9.0
110.6
12.0
3.S
50.3
3.S
3.K
4.0
135.0
7.8
9.0
6.5
NH4-N
8
8
C
6
4
6
4
4
4
4
6
4
4
4
4
4
4
2
12
6
4
4
6
4
4
4
34
6
4
20
6
4
4
36
C
6
4
mq/kq
Cl
saturated
paste
b'.OO
5.00
12.51
16.66
41. 6s
14.29
6.24
8.33
12. SI
24.99
12.51
12.51
12.51
174.95
412.39
374. 6B
24.99
62.50
124.96
337.41
62. SO
224.93
11.51
137.48
137. «S
374.88
S99.69
224.93
«9.98
412.40
41Z.40
449.86
1449. S»
474. 8S
167.46
62.50
74.96
OTFA
Zn Cu Mo Ft
j.b
3.i
4.3
2.3
2.S
3.1
i.S
2.5
2.b
31.0
7.5
2.5
1.3
1S.1
4.1
2.7
i.3
!.fc
16. S
4.6
3.5
2.3
£9.0
21.7
3.S
2.0
40.0
TO.S
2.8
76.0
9.7
3.7
2.2
41.0
7.1
H
2.6
-------
Table 29-continued
Site no.
4A
4B
4C
SA
SB
1C
4A
6B
(C
Sol)
depth
Inches
0-6
6-12
11 - 24
24 - 36
0-6
6-12
12 - 24
24 - 36
0-6
6-12
12 - 24
24-36
0-6
6 - U
12, - 2A
24-36
0-6
6-12
12 - 24
24-36
36+
0-6
6-12
12 - 24
24 - 36
0-6
6 - 12
12 - 24
24-36
0-6
6-12
12 - 24
24-36
36+
0- 6
6- 12
12 - 24
24 - 36
pH
saturated
paste
7.6
7.2
7.9
8.0
l.i
8.0
0.2
7.9
7.7
7.8
«.*
8.3
7.6
7.7
8.3
0.1
7.9
7.8
7.9
7.6
7.4
7.3
7.6
7.9
8.0
7.3
7.8
8.5
8.0
7.7
6.3
7.8
7.9
7.9
7.3
8.1
7.9
ft.O
Cond.
•mhos/car
1.9
1.0
0.7
0.7
2.4
1.3
2.4
S.I
2.8
2.0
1.0
0.6
0.6
0.7
0.5
1.1
1.6
1.0
O.S
2.0
3.*
1.6
0.6
0.8
1.1
2.8
3.2
1.4
2.0
3.8
1.1
9.0
22.0
20. 0
6.0
1.4
0.6
20.0
TUN
S
0.219
0.090
0.059
0.045
0.192
0.065
0.036
0.031
0.287
0.105
0.055
0.038
0.1 55
0.103
0.047
0.029
0.148
0.051
0.034
0.023
0.021
0.1«
0.091
O.Obl
0.034
0.119
0.068
0.044
0.031
0.179
0.055
0.033
O.°025
0.026
0.342
0.071
0.040
N03-N
9.8
2.0
0.8
0.4
4.8
1.6
0.8
0.8
21.0
3.5
0.3
0.4
4.6
0.6
0.4
0.4
6.8
1.2
0.0
0.4
0.9
7.S
2.0
0.8
0.0
9.8
0.0
0.8
0.4
11.8
0.8
O.t
0.8
o.fl
10.1
1.4
0.6
NaHCOs
P
122.0
4.3
1.3
2.6
936.0
9.0
11.0
10.3
174.0
15.5
13.0
12.0
62.6
9.0
6.0
4.0
100.6
11.3
2.3
4.0
9.0
72.6
8.3
2.3
4.0
46.3
3.0
3.5
3.5
113.6
6.0
8.3
10.5
9.5
183.0
6.5
8.8
NH4-N
50
6
6
4
46
6
4
6
58
U
6
6
20
8
6
6
32
8
6
6
6
28
6
10
20
30
10
10
10
36
10
10
10
8
5ft
10
8
8
roq/ko
Cr^
saturated DTPA
paste Zn Cu
199.94
137.48
87.50
74.98
374.88
224.93
287.43
462.37
274.91
424.37
62.50
74.98
49.98
99.97
37.5)
74.98
199.94
137.48
24.99
24.99
49.98
99.97
62.50
124.96
162.47
124.96
724.78
174.95
199.95
724.78
149.95
562.34
987.21
1324.59
1324.59
312.42
574.82
1524.53
Ho Fe
31.5
17.6
3.5
2.7
70.0
7.1
2.4
1.2
45. 0
7.6
5.8
4.6
17.3
6.5
4.2
2.5
16.2
4.1
3.3
3.4
5f
.6
27.5
8.4
3.7
3"j
.3
91 T
tJ. J
Sri
-U
3Q
.3
2O
. 7
17?
1 -Jt £
*T 7
9* /
3 2
J»t
1 Q
1*7
1.9
26.3
5.9
2.3
2.5
-------
Table 29-continued
—I
ro
Site no.
XA
KB
KC
7A
7B
7C
Soil
depth
Inches
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 •
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
PH
saturated
paste
7.5
ISS
7.9
8.0
8.0
7.4
8.0
7.8
7.5
ISS
7.6
8.6
9.1
b.S
8.5
8.0
7.1
7.0
7.8
7.5
7.5
6.1
8.3
8.1
Cond.
anhos/cmz
1.7
ISS
2.8
2.6
8.0
6.0
5.0
6.0
6.0
ISS
5.0
2.8
0.4
0.5
1.5
3.8
0.7
0.3
0.5
1.1
0.4
0.4
0.5
4.0
TKN
X
0.817
0.170
0.053
0.040
0.307
0.114
0.118
0.142
0.179
0.042
0.020
0.021
0.114
0.053
0.036
0.026
0.154
0.083
0.044
0.026
0.149
0.105
0.051
0.033
N03-N
174.0
152.5
11.4
2.4
102.5
36.4
0.6
3.2
136.5
45.1
10.5
4.0
0.8
0.6
0.6
0.8
1.0
0.6
0.4
0.4
0.8
0.6
0.4
0.6
KaHCOs
P
276.5
115.0
22.3
23.0
93.0
143.0
100.6
119.0
288.0
32.3
19.0
14.0
8.3
0.0
2.0
2.8
13.8
4.0
3.5
2.8
10.3
0.5
0.5
2.6
NH4-N
24
96
14
22
20
50
130
144
20
18
16
10
12
16
10
8
14
14
9
9
9
12
9
16
r
£1
saturj
past
3323
574
374.
1224.
1324.
1149.
1362.
587.
349.
174.
49.
37.
249.
824.
49.
49.
49.
99.
49.
37.
49.
849.
ng/kg
ited
-e in
.97
.82
.88
.62
.59
.64
.09
.34
.39
95
.98
.51
92
74
98
98
98
97
98
51
98
74
DTPA
Cu Kn Fe
49.0
19.1
5.2
3.4
49.0
43.0
36.8
26.9
12.2
6.1
5.6
3.7
4.6
3.8
2.3
19.9
8.9
5.3
4.4
7.5
4.3
3.0
2.1
ISS - Insufficient staple for analysis
-------
Table 30-Analysis of Lowry Bombing Range soils sampled spring of 1973
CO
Site no.
1A
IB
1C
2A
2B
K
3A
3B
Soil
depth
Inches
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
- 6
- 12
- 24
- 36
36*
- 6
- 12
- 24
- 36
36*
- 6
- 24
- 36
36*
- 6
- 12
- 24
- 36
36*
- 6
- 12
- 24
- 36
36*
- 6
- 12
- 24
- 36
36+
- 6
- 24
- 36
36+
- 6
- 12
- 24
pH
saturated
paste
7.8
3.8
9.2
9.3
9.0
8.2
8.8
9.3
9.4
9.0
7.9
9.1
9.5
9.4
8.7
8.0
8.1
9.1
6.6
8.4
8.0
8.6
9.2
9.4
9.4
7.8
6.3
9.3
9.2
9.0
7.9
8.2
0.9
9.0
8.6
S.l
7.9
s.r
Cond. _
•mhos/car
0.05
0.08
0.08
0.09
0.22
0.24
0.08
0.09
0.18
0.28
0.06
0.09
0.13
0.27
0.50
0.08
0.04
0.13
0.33
0.70
0.10
0.11
0.11
0.12
0.12
O.OS
0.05
0.12
0.24
0.30
0.15
0.15
0.17
0.17
O.Z1
0.12
0.13
0.15
TKN NaHC03
t NOj-N P
0.10
0.08
0.05
0.03
0.03
0.12
0.08
0.05
0.03
0.02
0.09
0.08
0.04
0.03
0.04
13
3
1
4
4
12
2
0
0
2
21
4
4
11
9
0.19 2 20
0.07 2 20
0.06 3 20
0.04 8 10
0.03
i 9
0.15 4 25
0.11 2 8
0.05 5 6
0.03
} 7
0.02 3 5
0.15
5 77
0.08 2 2
0.06 3 3
0.06 10 11
0.04 5 16
0.17 40 25
0.11 51 68
0.06 50 9
0.05 33 23
0.05 10 25
0.10 24 62
0.07 49 5
0.08 35 2
NH4-AC
K
250
265
230
198
198
288
158
130
115
115
293
193
175
180
206
359
163
225
184
198
221
235
150
158
93
298
S30
353
225
205
304
500
298
225
201
334
216
206
NH4-N
7
5
5
4
5
4
5
3
4
6
5
5
5
4
5
5
5
4
5
6
6
6
6
4
5
5
5
4
4
5
8
7
5
6
7
19
6
8
mo/kg
C1 «'^
saturated
paste
2.1
2.8
2.1
2.1
2.1
2.8
2.1
2.1
2.1
2.1
2.1
2.1
2.5
2.1
2.8
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2.8
2.1
2.1
1.1
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2.8
2.1
5.0
3.9
nTDA
JH
1.08
0.40
0.57
0.43
0:15
0.69
0.2»
0.20
0.12
0.11
0.55
0.13
0.14
0.12
0.21
7.05
0.33
1.16
0.35
0.32
8.43
0.40
0.19
0.26
0.09
9.55
0.11
0.25
ISS
1.23
15.70
5. 85
0.21
1.01
1.16
3.20
0.«3
O.lb
Cu
1.15
1.02
0.94
1.09
1.31
1.22
1.02
0.66
0.52
0.40
1.27
1.11
0.77
0.65
0.74
4.70
0>72
1.49
0.60
0.76
7.10
1.45
0.93
0.65
0.35
7.40
1.07
0.93
ISS
1.46
9.40
3.11
0.74
1.17
1.17
3.60
1.13
1.00
Mr
20.60
11.30
6.45
3.55
2.50
26.50
8.50
6.70
3.10
2.05
22.50
11. IS
6.40
1.0S
6.00
tt.SO
13. bS
8.55
3. 55
1.6*
19.50
17. OJ
4. 95
3.35
.2.45
2s. 00
29.00
9. 53
ISS
3.30
50.50
19.00
6. 65
7.95
7.90
19. SO
13. CO
9.65
te
9.9
4.1
3.7
5.3
$.0
b.5
5.7
5.0
3.9
2.5"
9.9
4.9
4.3
3.6
3.9
16.1
7.1
7.2
4.1
3.9
19.5
7.6
4.7
3.6
2.3
29.2
13.0
5.2
ISS
3.7
35.0
17.6
5.3
a.o
7.2
10.4
5.3
3.6
-------
Table 30-continued
Site no.
3C
4A
4B
4C
5A
96
5C
Soil
depth
Inches
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
24
0
6
12
M
0
b
12
24
0
i
12
24
- 36
36*
- 6
- 12
• 24
- 36
36+
- 6
- 12
- 24
- 3*
36+
- 6
- 12
- 24
- 36
35+
- 6
- 12
• 24
- 36
36+
- 6
- 12
- 24
- 36
36+
- 6
- 1
0
47
21
29
27
10
73
7
2
3
5
13
tt
16
11
4
20
3U
2
1
1
NaHCOs
P
9
10
40
13
5
7
13
61
4
6
7
it
105
IS
9
7
18
54
7
S
6
18
114
13
7
10
19
I2r
17
23
14
17
61
9
6
T.
21
NH4-AC
V.
126
79
410
500
403
166
175
230
134
146
146
119
315
193
170
158
158
453
225
184
206
225
321
201
139
150
143
450
230
201
138
111
270
235
175
170
166
NH4-N
8
7
9
11
7
6
7
7
6
6
6
6
11
10
6
7
9
12
12
9
7
8
8
6
7
5
6
13
9
6
7
7
14
8
9
8
11
mo/kg
Cl
saturated
paste
5.0
3.9
3.9
C.2
3.9
3.9
6.0
2.1
2.1
2.1
2.5
3.2
2.5
1.4
.4
.4
.4
.4
.4
2.5
2.5
2.5
2.5
2.5
2.5
1.4
2.5
2.5
2.5
i2-5
Is
2.5
2.5
2.5
2.5
2.5
3.2
91PA
Zn
0.21
0.23
3s. 00
0.81
0.70
1.53
3.05
3.95
0.22
0.50
0.42
0.35
7.70
1.90
0.84
0.53
1.32
6.75
0.67
0.43
0.47
1.53
18.40
l.bl
0.83
1.34
2.90
13.20
1.23
1.41
0.71
3.40
11.40
0.94
1.06
0.76
3.50
Cu
O.S5"
0.53
13.30
1.37
1.13
1.17
2.80
2.50
5.90
9.30
1.09
1.23
5.30
1.73
l.CO
0.'92
1.57
4. SO
1.43
1.13
1.31
1.64
11.10
1.47
1.23
1.19
1.92
9.20
1.61
1.53
0.77
1.21
4.00
1.41
1.04
1.09
2.30
»*>
Z.40
0.95
43.50
18.50
6.25
3.45
5.35
9. OS
6.20
6.05
4.C5"-
3.00
62. CO
13.55
6.20
3.96
4.65
4S.50
11.15
6. 25
3.55
2. SO
13. =0
7.80
S.5S
4.10
5.30
27.00
10.35
4.15
2.25
3.C5
17.00
12.10
7.tO
4.50
4.45
F*
3.5
2.2
23. S
s.i
5.6
4.0
5.7
7.1
4.9
3.fc
2.8
3.Z
16.1
7.7
0.1
4.1
4.7
It. 3
6.1
6.3
6.7
7.1
13.9
7.1
5.6
4.1
6.7
16.3
6.7
5.1
3.3
4.3
U.I
6.8
S.7
4.5"
5.7
-------
Table 30-continued
en
Site no.
6A
68
6C
ICA
KB
KC
7A
7C
Soil
depth
Inches
0
6
li
24
0
6
It
24
0
6
12
24
0
6
12
14
0
6
12
24
0
6
12
24
0
6
1
-------
Table 30-continued
SUe no.
7C
Soil
depth
Inches
24 - 36
0-6
6-12
12 - 24
24 - 36
36+
PH
saturated
paste
9.5
8.3
8.4
8. S
8.8
9.0
Cond.
«nhos/cmz
0.13
0.55
0.31
0.07
0.08
0.07
TKN
X
0.02
0.19
0.05
0.02
0.03
0.03
N03-N
1
63
3
1
1
1
NaHCOa
P
2
170
24
2
1
2
t»<4-Ac
K
50
158
64
56
56
39
NK4-N
7
41
24
4
4
7
rro/ko
Cl
saturated
pzste
2.1
2.1
2.1
2.1
2.1
2.1
In
0.22
20.00
2.19
0.42
0.47
0.93
Cu
0.09
12.10
0.99
0.19
0.32
0.20
CTPA
Mn
1.6S
23.50
7.20
4.75
1.65
1.10
Fe
3.9
36. 5
16.6
13.6
9.7
6.9
cr>
1SS - insufficient sanple for analysis
-------
Table 31-Analysis of Lowry Bombing Range soils sampled spring of 1974
«!9/k9
Soil P« Cl
depth saturated ConU. , TKN KaHCOa NH4-AC saturated
Site no. Inches paste «»hos/cmz % N03-N P 1C NH4-H paste
P7PA
In Ca Mo ft
1A
IB
1C
2A
2U
K
3A
ib
3C
4A
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
I* -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
6
1Z
24
36
6
12
24
36
6
12
24
36
6
12
14
36
6
12
24
35
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
7.0
7.4
7.9
7.8
7.4
7.7
7.3
7.7
7.3
7.7
7.8
7.3
7.3
7.3
7.7
ft.o
7.2
6.9
7.7
6.2
6.3
7.1
8.0
8.?
6.4
7.5
8.2
8.1
7.8
7.7
7.7
7.7
7.6
ISS
8.0
7.9
7.t>
7.6
0.9
0.5
0.4
0.7
0.7
0.6
1.8
7.6
1.5
0.6
0.4
0.6
1.2
0.6
0.5
0.6
1.1
0.6
0.6
1.0
0.6
0.7
2.9
C.2
7.)
2.7
2.7
7.1
7.1
3.4
3.3
4.7
9.9
ISS
3.1
tt.2
».
6.5
3.7
41.0
13.7
9.3
6.3
5.4
5.6
4.6
6.4
6.0
4.1
5.7
5.3
5.1
4.3
22.1
6.6
6.6
5.5
34.3
15.2
9.2
5.5
34.0
14.0
5.9
4.0
4S.5
19.6
6.2
9.1
35.$
18.7
15.2
6.9
41. fc
30.0
7.5
6.4
24.1
7.1
-------
Table 31-continued
Site no.
48
4C
5A
SO
sc
6ft
68
6C
7A
4"
Soil
depth
Incites
12 -
24 -
0 -
6 -
1? -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
72 -
24 -
'0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
0 -
6 -
12 -
24 -
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
12
24
36
6
11
24
36
6
12
24
36
6
If
24
36
pH
saturated
paste
8.1
8.2
7.2
6.7
7.8
1.7
7.4
7.0
7.7
7.9
7.4
7.3
7.7
7.9
7.5
7.7
7.9
7.9
7.5
7.2
7.5
7.8
7.4
8.0
8.1
8.1
7.2
7.6
7.6
7.9
7.3
7.5
7.7
7.6
7.3
7.6
7.5
7.6
Cond.
mhos/cm*
2.4
2.1
7.6
4.7
1.7
4.6
6.5
3.6
3.7
4.9
1.3
1.4
1.6
2.6
3.2
2.6
2.2
1.9
3.C
2.8
1.3
3.1
5.5
2.8
5.5
16.5
1.0
1.0
1.0
0.9
7.6
3.3
1.8
4.3
4.0
4.3
5.5
s.a
TKH
X
0.07
0.04
0.31
0.10
0.06
0.04
0.38
0.12
0.07
0.07
0.29
0.10
0.06
0.04
0.21
0.08
0.06
0.05
0.31
0.13
0.05
0.03
0.34
0.06
0.04
0.03
0.11
0.07
0.04
0.02
0.41
0.07
•0.03
0.03
0.12
0.15
0.1U
0.35
K03-N
55
45
330
190
36
31
340
150
87
83
81
30
44
64
190
93
6U
33
240
91
14
23
160
47
10
2
2
0
0
0
500
340
21
22
87
34
2
1
NaHC03
P
5
9
275
21
8
15
380
42
10
13
290
16
8
10
175
6
5
8
385
65
15
17
290
17
14
13
60
2
2
5
350
16
10
24
175
165
155
130
NH«-Ac
K
200
191
378
465
265
175
393
650
308
235
450
388
240
183
473
243
194
205
358
438
240
205
303
188
133
159
308
188
145
123
299
158
115
73
183
175
195
145
NIU-N
5
4
9
S
4
4
7
8
8
7
11
7
5
6
13
8
8
7
12
17
6
5
9
6
6
6
7
S
B
7
14
6
7
7
23
41
112
122
as/kg
tl
saturated
paste
200.0
225,0
550.0
340.0
140.0
240.0
420.0
310.0
375.0
740.0
20.0
80.0
100.0
255.0
160.0
1GO.O
190.0
188.0
140.0
80.0
70.0
1SO.O
.440.0
325.0
75*0.0
1840.0
44.0
130.0
136.0
75.0
420.0
270.0
260.0
210.0
420.0
140.0
212.0
200.0
OT?A
In
0.43
0.96
35.0
1.17
0.38
O.S2
41.5
2.00
36.5
4.60
0.63
0.62
60.0
2.40
17.8
0.99
4.20
0.32
0.95
1.51
41.0
1.93
0.51
0.95*
19.0
0.66
0.57
0.61
0.16
0.13
79.0
1.96
1.00
3.40
27.0
21.5
22.5
17.5
Cu
1.3?
1.4l
14.20
2.00
1.31
1.24
15.35
2.60
19.40
4.90
1.2i
1.02.
28.20
Z.2S>-
i.&ii
i,i&
4.90
1.34
1.47
1.56
28.00
2.52
1.30
1.52
8.30
1.06
1.1&
1.24
0.96
0.64
36.6
2.08
0.75
1.C8
1.87
12.90
7.90
6.30
m
6.6
5.4
101.0
43.0
7.1
4.7
51.0
41.5
30.0
27.5
5.3
5.9
29.0
0.8
5.0
2.9
17.0
8.0
8.5
6.7
25.0
15.0
6.6
4.4
12.6
7.2
5.5
3.6
3.9
3.7
37.0
7.1
4.0
3.9
39.5
66.0
107.0
1*4.0
ft
5.4
5.2
35.0
23.5
6.7
5.5
37.2
17.9
31.5
26.2
8.0
5.4
43.0
13.9
7.8
6.3
M. S
8.7
tt.2
8.7
37.1
12.7
7.2
6.9
20.3
7.1
6.4
4.9
6.3
5.0
2S.5
8.7
6.4
7.0
40.0
49.f
29.ff
24 .2.
o>
-------
Table 31-continued
Soil
depth
Site no. Inches
76 0-6
6-12
12 - 24
24-36
« 0
f
12
24
n» o
6
1C
6
12
24
36
5
12
24
24-36
PH
uturated
paste
7.7
7.6
7.6
7.8
7.5
7.4
8.0
7.7
7.i
7.3
7.0
7.0
Cond.
mtus/af
3.8
3.7
3.8
4.3
9.0
9.7
8.2
7.7
4.0
4.4
7.7
6.7
?
0.04
0.05
0.07
0.06
0.14
0.12
0.11
0.14
0.17
0.08
0.02
0.02
NQ3-N
10
18
17
7
180
240
3
24
60
170
310
220
IUHCOJ
P
10
23
60
22
230
125
130
170
400
276
SO
48
NH4-AC
K
153
183
93
68
243
193
170
260
250
170
133
140
NH4-H
10
9
22
32
13
38
160
146
15
12
10
9
,*/„„
CJ
saturated
piste
65.0
90.0
10.0
135.0
133.0
1179.0
75.0
762.0
356.0
269.0
490.0
415.0
in
1.18
3.50
12.50
3.40
21.0
26.0
16.5
40. S
26.5
5.2
3.7
91
CM
1.04
1.77
4. tO
l.SO
8.80
14.95
0.70
7.50
11.20
7.4b
3.M
4.50
i*
Mo
4.8
5.9
14.8
25.0
10.0
£.9
33.0
55.5
9.4
5.9
10.7
4.2
f*
6.6
10.7
19.8
24.2
26.7
41. y
34.6
40.5
32.0
2J.6
1S.5-
16.0
-------
Table 32-Analysis of Lowry Bombing Range soils sampled fall of 1974
Soil pH
depth saturated Co
Cite no. Inches paste mho
mq/Vq
Cl
ml. TKN N»HC03 NHfl-Ac saturated , OT?A
s/enz J N03-N P K NH4-H paste Zn Cu nn te
ot>
o
1A
18
1C
ZA
23
K
3A
3B
3C
4A
0 - 6
6-12
U - 24
24-36
0-6
6-12
ia - 24
24 - 36
0 - 6
6-1?
12 - 24
Z4 - 36
0 - 6
6-12
12 - 24
24 - 36
0-6
6 - 12
12 - 24
24 - 36
0 - 6
6 - 12
12 - 24
24 - 36
0 - 6
6 - 12
12 - 24
24 - 36
0 - 6
6-12
12 - 24
24 - 36
0-6
6 - 12
12 - 24
24 - 36
0-6
6-12
7.5
7.8
8.0
8.0
7.6
7.8
7.9
7.7
7.1
8.2
8.1
8.1
7.5
7.5
e.o
6.3
7.3
7.b
8.1
8.3
6.5
6.9
8.1
7.8
7.1
7.1
7.6
7.7
6.4
6.9
7.5
7.7
7.7
7.9
8.0
6.0
7.1
7.0
0.6
0.4
0.4
0.7
0.5
0.5
0.9
5.2
1.1
1.7
6.5
8.7
1.2
0.7
0.5
0.8
0.9
0.5
0,5
1.0
8.7
1.6
0.9
4.0
8.7
3.7
2.6
4.7
9,2
4.4
2.0
1.9
1.7
1.0
0.6
0.8
0.9
3.9
0.116
0.091
0.041
0.029
0.159
0.079
0.032
0.028
0.070
0.066
0.043
0.024
0.174
0.081
0.056
0.033
0.150
0.075
0.045
0.027
0.197
0.088
0.057
0.038
0.292
ISS
0.058
0.043
0.238
0-.103
0.064
0.063
0.243
0.21*
0.091
0.060
0.219
0.097
13
2
1
2
5
6
2
1
1
43J
75
6
3
570
155
66
42
600
275
67
33
400
300
94
28
220
270
22
2
1
4
4
1
1
2
17
4
10
11
80
12
12
12
72
5
2
6
120
14
5
17
385
43
4
15
325
14
4
11
225
225
53
21
165
8
393
240
220
235
325
220
210
205
26S
338
225
235
650
5oO
273
230
393
255
398
220
405
580
430
273
40S
700
630
500
1030
5BO
425
245
700
500
650
530
418
700
21
12
10
7
14
10
S
15
14
13
17
!i
12
11
9
10
10
13
5
7
47
17
9
11
32
I5S
10
7
30
18
9
7
19
27
13
13
19
29
<2
<2
<2
<2
5
<2
2
2
10
6
22
22
2
't
<2
2
<2
2
2
10
10
2
2
2
2
14
15
15
20
12
8
8
10
12
12
5
5
'25-
0.6
0.2
0.2
0.2
0.6
0.2
0.2
Q.c
0.6
0.3
0.2
0.2
10.5
1.0
0.5
0.6
6.3
0.3
0.2
0.2
19.0
0.7
0.3
0.2
41.5
2.8
2.1
0.3
33.0
0.6
0.4
3.0
16.0
15.5
1.3
0.4
26.0
1.2
0.7
0.7
0.7
0.7
0.6
0.7
0.6
0.7
0.7
1.0
0.7
0.7
5.4
1.2
0.9
0:7
5.7
0.9
0.7
0.6
5.9
1.2
0.8
0.8
17. a
1.9
0.9
1.1
12.6
1.5
1.1
2.7
12.5
1.6
0.9
0.7
12.0
1.6
13.7
7.4
4.2
3.2
6.9
5.2
2.6
3.2
13.2
6.7
4.1
1.7
17.0
14.0
4.6
2.4
15.0
7.6
4.6
3.6
34.0
20.0
6.7
3.1
18.5
14.0
G.6
3.5
98.0
25.0
7.8
2S.5
99.0
44.0
20.0
8.0
60.0
23. S
8.9
4.9
7.0
7.6
6.0
S.S
7.1
6.3
15,2
10.3
5.4
5,9
20.2
9.6
10. b
10.2
24.4
9.9
8.9
7.7
64.5
26.fi
10.9
6.4
59.0
21.3
9.3
7.3
25.7
U.9
r.7
9.7
63.0
47.0
17.4
6.3
65.0
21.0
-------
Table 32-continued
00
S*t« BO.
48
4C
5A
n
St
6A
63
7C
70
Soil
depth
Inches
1? - 24
24 - 36
0-6
6 - 12
12 - 24
24 - 36
0-6
6 - 1?
12 - 24
24 - 36
0-6
6 - 12
12 - 24
24 - 36
0-6
6 - It
12 - 24
24 - 36
0-6
6-12
12 - 24
24-36
0-6
6-17
12 - 24
24 - 36
0-6
6-12
12 - 24
24 - 36
0-6
6-12
12 - 24
24 - 36
0-6
6-12
12-24
24 - 3<
PH
saturated
paste
3.1
8.0
7.3
7.9
8.1
8.5
7.5
7.8
b.4
8.4
7.S
8.0
8.3
8.4
7.8
li.b'
n.3
8.1
7.0
7.4
8.0
8.1
7.5
7.8
8.2
8.5
7.9
8.2
8.3
8.1
7.6
7.C
7.9
9.1
7.6
7.5"
7.4
7.5
Cond.
nnhos/cn2
2.4
4.6
2.8
2.0
1.7
1.6
6.8
3.0
1.3
1.7
8.5
4.2
2.0
3.0
4.1
2.0
2.0
5.7
15.4
.1
.4
. 7
.8
.6
.0
2.2
1.4
8.7
2.5
11.0
7.1
1.7
0.9
1.1
4.1
6.2
6.2
4.1
TfN
1
0.056
0.033
0.162
0.096
0.051
0.034
0.280
0.089
0.054
0.034
0.341
0.106
O.ObO
0.035
0.297
0.076
0.039
0.030
0.520
1SS
0.047
0.03*
0.136
0.064
0.036
0.026
0.145
0.029
0.052
0.022
1SS
0.080
0.036
0.023
O.iOO
o.oai
0.065
0.076
H03-N
64
3
160
86
42
25
330
94
81
34
6CO
290
130
51
380
160
65
61
1000
250
32
21
46
23
2
1
32
16
42
2
210
29
1U
6
120
220
190
82
NeHCOj
P
3
H
115
7
4
7
440
21
10
11
450
44
15
13
345
14
5
11
450
30
7
7
125
4
5
7
175
12
8
10
170
10
1
1
650
34
7
90
NH4-Ae
K
393
265
405
283
278
290
580
255
225
193
363
245
210
200
363
308
273
295
430
375
250
2bB
425
2<5
205
178
342
230
220
250
490
245
250
240
550
283
260
295
NH4-N
23
19
23
17
16
21
9
10
5
9
32
35
16
19
22
22
14
19
11
20
14
14
20
16
18
15
20
15
22
15
1SS
44
19
16
66
41
20
20
irg/kg
Cl
saturated
paste
10
20
8
12
10
8
25
12
22
22
45
22
12
8
25
10
8
5
40
IB
2
2
a
12
5
8
5
25
18
25
32
6
2
5
25
45
38
25
**
0.3
0.2
li.5
0.3
0.2
0.2
56.0
1.0
0.6
0.6
68.0
3.7
0.9
0.5
45.0
0.6
0.3
0.5
85.0
4.0
0.2
0.3
10.2
0.2
0.3
0.2
15.2
0.2
0.3
0.3
12.0
0.6
0.1
0.2
66.0
1.3
0.4
6.5
DT
Cu
1.1
1.0
7.4
O.S
0.9
0.9
35.0
1.5
1.1
1.1
10.0
2,3
1.2
1.0
42.0
U4
1.0
1.3
4.0
3.2
0.9
O.S
6.8
0.9
0.8
0.8
9.6
0.9
1.0
0.9
2.0
0.9
0.7
0.7
32.4
1.9
1.4
3.9
PA
Mn
5.4
11.0
15.0
7.4
6.3
5.0
31.0
9.2
5.4
4.2
26.0
7.7
5.1
4.7
26.0
9.1
1.4
4.1
ba.O
lb.0
3.0
4.4
8.5
5.7
4.0
3.4
10.0
3.3
5.6
2.8
26.0
7.4
4.7
4.0
26.0
26.0
7.1
7.9
fe
11.7
7.3
30. i
9.0
9.0
7.b
67.0
12.0
9.4
o.4
72.0
14. (5
5.9
6.4
71.0
12.1
11. Z
9.3
Cf^
•0
20.9
9.7
7f
.4
Zl.6
9.9
7.9
7.1
17.B
7.9
10.0
6.4
23.1
9.3
9.4
9.4
9.6
12.2
11.1
U.I
-------
Table 32-contlnued
SUt no.
KA
KB.
Soil
depth
Inches
0
6
12
24
0
6
12
24
- 6
- 12
- 24
- 36
- 6
- 1*
- 24
- 36
PH
saturated
paste
7.4
7.5
7.7
7.9
7.4
l,t
7.3
7.8
Cond.
.mhos/cor
5.5
5.4
6.2
6.2
S.8
7.4
6.9
5.3
TKN
S
0.157
0.144
0.123
0.176
0.242
O.lOb
0.124
0.129
N03-N
29
42
9
1
130
220
160
2
N»HC03
135
125
115
125
400
100
95
85
NH4-AC
K
170
170
173
193
260
175
165
125
»H4-N
360
ISS
165
ISS
36
44
240
600
_^ MC/kd
Cl
saturated
paste
62
52
38
18
32
30
33
48
DTfA
in
16.9
16.1
10.2
14.0
43.0
18.5
22.0
26.0
Cu
8.4
7.0
6.8
6.9
19.0
9.6
12. if
9.0
Mn
SZ.O
85.0
99.0
81.0
8.8
39.0
S4.C
36.0
Ft
9.9
9.7
6.9
10.7
53.0
70.0.
Ss.O
37. «.
00
ro
ISS • Insufficient, staple for
-------
REFERENCES
1. Soil Conservation Service, 1971. Soil Survey Arapahoe County, Colorado,
United States Department of Agriculture.
2. Soil Conservation Service, 1974. Soil Survey Adams County, Colorado,
United States Department of Agriculture.
3. Jackson, M.L., 1958. Soil Chemical Analysis. Prentice Hall, Inc.,
Englewood Cliffs, New Jersey.
4. Watanabe, F.S. and S.R. Olsen, 1965. Test of an Ascorbic Acid Method
for Determining Phosphorus in Water and NaHCOS Extracts from Soil. Soil
Science Soc. Amer. Proc. 29:677-678.
5. Pratt, P.P., 1965. Potassium. In C.A. Black (ed.) Methods of Soil
Analysis, Part 2-Chemical and Microbiological Properties, Chapter 71,
p. 1026.
6. Lindsay, W.L. and W.A. Norvell, 1969. Development of a DTPA Micronutrient
Soil Test, Agron. Abstr.
83
-------
GLOSSARY
B
Ca
Cd
CEC
Cl
cm
COD
CSU
Cu
DTPA
FDI
Fe
Fed 3
9
ha
K
kg
LBR
Metro
Mg
MGD
umho/cm
mmho/cm.
Mn
Mo
N
Na
NCRDC
NHt
NH-f-N
NO,
N03-N
OM
P
Pb
PH
ppm
TKN
TS
Zn
boron
calcium
cadmium
cation exchange capacity
chlorine
centimeters
chemical oxygen demand
Colorado State University
copper
di ethylenetriamenepentaacedi c aci d
flash dryer-incinerator
iron
ferric chloride
grams
hectare
potassium
kilograms
Lowry Bombing Range
Metropolitan Denver Sewage Disposal
District No. 1
magnesium
million gallons per day
micro mho per square centimeter
mi Hi mho per square centimeter
manganese
molybdenum
nitrogen
sodium
Northern Colorado Research & Demonstration
ammonia
ammonium
ammonium nitrogen
nitrate
nitrate nitrogen
organic matter
phosphorus
lead
negative logarithm of the hydrogen
ion activity
parts per million
total Kjeldahl nitrogen
total solids
zinc
Ctr.
84
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-054
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
COMPREHENSIVE SUMMARY OF SLUDGE DISPOSAL RECYCLING
HISTORY
6. REPORT DATE
April 1977 (Issuing Date)
S. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
John C. Baxter, William J. Martin, Burns R. Sabey,
William E. Hart, David B. Cohen, and Carl F. Calkins
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Metropolitan Denver Sewage Disposal District No. 1
3100 East 60th Avenue
Commerce City, Colorado 80022
10. PROGRAM ELEMENT NO.
1BC6H
11. CONTRACT/GRANT NO.
68-03-2064
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Gin. ,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 1967-1974
14. SPONSORING AGENCY CODE
EPA/600/14
16. SUPPLEMENTARY NOTES
16>A^inceT1971 the only mode of sludge disposal used by Metro has been land application.
A number of different application procedures have been tried over the intervening
years. The development of methodology and problems associated with each procedure
are discussed in the text.
Continuous applications of sludge to the soil at the Lowry Bombing Range since 1969
have raised the concentration of nutrients, metals, salts and organic matter. The
effects of these excessive loading rates on the soil, crops and environment are evalu-
ated.
The effects of various sludge applications to soil on germination, emergence, sub-
sequent plant growth, and uptake of heavy metals are examined. Inhibition of germin-
ation decreased with increasing soil sludge incubation periods or when dried sludge
was used, suggesting that salts or some volatile component within the sludge was in-
hibiting germination.
Microbial counts of fecal coliform bacteria in sludged plots showed no appreciable
differences from control plots after a 6 month incubation period.
Liquid sludge added to shallow earthen drying basins demonstrated that water is
lost through soil percolation in addition to evaporation, and that about half the N
content of sludge is lost. A discussion of future research needs is
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