.PRODUCTION OF NON-FOOD-CHAIN CROPS
WITH SEWAGE SLUDGE
by
Lilia A. Abron-Robinson.
Cecil Lue-Hing
PEER Consultants, Inc.
Edward J. Martin
David W. Lake
Environmental Quality Systems, Inc.
Rockville, Maryland 20852
Contract No. 68-03-2743
Project Officer
Gerald Stern
Municipal Environmental Research Laboratory
Cincinnati, Ohio
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO
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This reports has been reviewed by the Municipal Environmental Research
'Laboratory, LT..S,: Environmental Protection Agency, and approved for publica-
Ition. 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 recom-
imendation for use.
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FOREWORD ..
The U.S. 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 testimonies to the deterioration of our natural environment. The com-
plexity of that environment and the interplay of its components require a
concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution,
and it involves defining the problem, measuring its impact, and searching for
solutions.... The Municipal Environmental Research Laboratory develops new and
improved technology and systems to prevent, treat, and manage wastewater and
solid and hazardous waste pollutant discharges from municipal and community
sources, to preserve and treat 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 and provides a most vital
communications link between the researcher and the user community.
The utilization of sewage sludge as~ a resource has been proposed by the
U.S. Environmental Protection Agency. In this regard, this study examines the
feasibility and market potential for the production of non-food-chain crops
with sewage sludge.
Francis T. Mayo, Director
Municipal Environmental
Research Laboratory
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ABSTRACT
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Feasibility.and market potential were determined for non-food-chain crops!
cultivated using sewage sludge. i
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: Non-food-chain crops that are currently being sold on the open market or
that have a. good potential for marketability were selected. From a list of 20j
!crops, 3 were selected and subjected to a cost analysis to determine how the!
:costs for cultivation using sewage sludge compared with the costs for cultiva-j
tion using commercial fertilizer. j I
I i . i
: _ Cotton, _socU and. energy biomass trees were_determined_ tq_Jiave__the[.best]
potenti al~Tor cultivation using sewage;studg~e"i based on the~market'values "and1
nutrient requirements for each crop, and on the hectares presently under culti-j
vation for production of these crops. ' I
; I !
: Results indicate that large quantities of sewage sludge can be used, based:
solely on the nitrogen and phosphorus requirements for the cultivation of these;
crops. In addition, it was determined that although the total costs for
fertilization using commercial fertilizer are less than the costs for using!
sewage sludge, the latter would be viewed more favorably if the costs were.
borne by the municipality generating the sludge. ' j
\ ', I
This report was submitted in fulfillment of Contract No. 68-03-2743 by PEER;
Consultants, Inc. and-Environmental Quality Systems, Inc. under the sponsor--
ship of the U.S. Environmental Protection Agency. This report covers the-
period October 1, 1978 to December 1979, and work was completed as of May 1980. 1
IV
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CONTENTS
Foreword ' i i i
Abstract iv
Figures vi
Tabl es v i i
Abbreviations and Symbols x
Acknowl edgements xi i
1. Introduction i;
2. Conclusions ... 2
3. Recommendations 4
4. Fertilizer and Energy Value of Municipal Sewage Sludge 5
Introduction..; * 5
" Quantity of sewage sludge generated by POTW'S 5
Plant nutrients in sewage sludge 6
Energy requirements 11
Summary 13
5. Methodology for Selection of Non-Food-Chain Crops 15
6. Non-Food-Chain Crops Amenable to Cultivation
Using Sewage. Sludge 19
Discussion of potential crops 19
Most promising non-food-chain crops 50
7. Case Studies 53
Methodology ; 53
Case study 1: cotton production 62
Case study 2: sod production 69
Case study 3: biomass production 72
Summary 73
8. Cost Analysis 75
Background 76
Discussion and summary.. 78
References 90
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FIGURES
Number . rage
1 States with significant cotton
producti on 48
2 States with significant soybean
producti on r 49
! ;
i ! . . -
3 _ States, with .significant sod.producti^n _/. _ 55
4 Millions of acres and percentage of land
potentially available for energy biomass
tree production by region (assuming the
utilization of 10% of the non-agricultural
land in each region) 56
5 Costs of land application of sludge by
injection 63
6 Costs of sludge application by surface
irrigation 64
7 Costs of truck-spreading liquid sludge g5
8 Costs of liquid sludge transport - 20 miles 84
9 Costs of liquid sludge transport - 40 miles 85
10 Costs of liquid sludge transport - 60 miles..., gg
11 Costs of sludge cake transport - 20 miles gy
12 Costs of sludge cake transport - 40 miles ,^_ Pp
j r . .. .....^ JJQ
13 Costs of sludge cake transport - 60 miles gg
vi
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. TABLES
Number Page
6 N, P, and K Values for Primary Sludges
.
10 Comparisons of Energy Requirements for the
Production of Inorganic Nitrogen
Major Plant Nutrients Present in Various
Sewage Sludge Sources, Percent Dry
Weight ............................................. 6
N, P, and K Levels in Anaerobic and Aerobic
Digested Sludges ................................... 7
Nutrient Content -of Sewage Sludge Before and
.-After-Wet Air Oxidation ..... .......... ..v... ....... ...... 3
Impact of Lagooning on the Nitrogen Content
of Sludge .................. ........................ 8
Nitrogen Content of Sludge Before and After
Heat Drying ....................................... . 3
7 Nutrient Content of Two Waste-Activated
Sludges .............. ... ........................... g
8 Nutrient Content of Various Dewatered
Sludges ..................................... ....... j.0
9 Daily Value and Costs of Nutrients Contained in
Municipal Sludge ................................... IQ
11 Comparisons of Energy Requirements for the
Production of Inorganic Phosphorus ...... ........... 12
12 Comparisons of Energy Requirements for the
Production of Inorganic Potassium .................. 12
13 Energy Requirements and Costs for Total
Municipal Sludge Incineration ...................... 13
vii
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Number ; ! - f Page
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14 Categories of Non-Food-Chain Crops Selected
for Study 16
!
15 Possible Non-Food-Chain Crops' Amenable to
Cultivation Using Sewage Sludge 18
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16 Types .and Distribution of Deciduous Trees
(Hardwoods) in the United States 21
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17 Nutrient Requirements for a Conventional
Forest and Nutrient Application Rates for
Forest Crops \ 29
! \
18 Types1and Distribution of Coniferous Trees
(Softwoods) in the United States 34
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19 Non-Fobd-Chain Crop Uses for Cotton and
Soybeans ; 46
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20 Kilograms of N, P, and K Applied to Cotton
and Soybeans ; 50
r !
21 Most Promising Non-Food-Chairt Crops Suitable
for Cultivation Using Sewage Sludge 51
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22 Cost of Applying Liquid Sludge to Provide
Nitrogen for Cotton Cultivation 66
!
23 Cost of Applying Liquid Sludge to Provide
Phosphorus for Cotton Cultivation 67
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24 Cost of Applying Liquid Sludge to Provide
, Nitrogen for Sod Cultivation 70
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25 Cost of Applying Liquid Sludge to Provide
Phosphorus for Sod Cultivation ; 71
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26 Cost of Applying Liquid Sludge to Provide
Nitrogen for Biomass Cultivation 74
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TABLES (continued)
Number Page
27 Cost of Applying Liquid Sludge to Provide
Phosphorus for Biomass Cultivation ................. 75
28 Cost Comparisons for Sludge and Commercial
Fertilizer ................ . ... .....................
29 Cost Comparisons for Sludge vs. Commercial
, - ...... - ....... Fertl 1.1 zer; .v. .-« .--.--. , . . ... .V. . .-. ; -r. ... .^ .-. . .-. ;-.- --QI
IX
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...ABBREVIATIONS AND .SYMBOLS
ABBREVIATIONS
Btu
CAST
cm
d
DMTE
DMT
DT
ft,
ft* ~
gal
ha
hp
J
Kcal
Kg
kJ
kl
KW
1
LA/OMA
Ib
M3
MJ
mil
ml
mm
MOP
MSC
MSDGC
MT
NFCC
POTW
SIC
WAO
WPCF
yr
British thermal unit
Council for Agricultural Science and Technology
centimeter
day
dry metric ton equivalent
dry metric ton
;dry ton ;
_feet ......
square f eet~
cubic feet
gallon
hectare(s)
horsepower ;
joule
kilocalories
kilogram
kilojoule
kiloliter
Kilowatt
liter
Los Angeles/Orange County Metropolitan Area
pound
meter
square meter
cubic meter
mi 11ion
mi Hi liter
millimeter
Manual of Practice
Milwaukee Sewage Commission
Metropolitan Sanitary District of Greater Chicago
metric ton
non-food-chain crop(s)
publicly owned treatment works
Standard Industrial Classification
wet air oxidation
Water Pollution Control Federation
year
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^.SYMBOLS
ABBREVIATIONS AND SYMBOLS (continued)
K potassium
ICO potassium oxide
N nitrogen
NIU ammonia ;
NPK nitrogen, phosphorus, potassium ratio
P phosphorus
PoOr phosphorus pentoxide
3T percent
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__AC.KNQWLEp(3MENTS.,
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The assistance of the many Federal agencies and private corporations and:
businesses is gratefully acknowledged. Also, the cooperation and overall pro-'
;ject coordination by Mr. Gerald Stern (EPA Municipal Environmental Research;
;Laboratory, Cincinnati, Ohio) as the Project Officer is appreciated. i
: i
<
; The project investigators wish to express their appreciation to MsJ
Beverly Preston, Ms. Sharon Fried, and Ms. Susan Orye who spent many hours on;
ithe manuscript preparation. The project investigators are also indebted to,
!their colleagues for their assistance 'and suggestions during the development:
;of the information presented in this report. j
xii
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ACKNOWLEDGMENTS
| The assistance of the many Federal agencies and private corporations and;
[businesses is gratefully acknowledged.; Also, the cooperation and overall pro-:
;ject coordination by Mr. Gerald Stem (EPA Municipal Environmental Research!
iLaboratory, Cincinnati, Ohio) as the Project Officer is appreciated. j
' ' [ ; '
\ The project investigators wish to express their appreciation to Ms.j
JBeverly Preston, Ms. Sharon Fried, and!Ms. Susan Orye who spent many hours on!
;the manuscript preparation. The project investigators are also indebted to;
{their colleagues for their assistance :and suggestions during the development,
jof the information presented in this report. !
XII
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JEGHQJLL
INTROdUCTION
[BACKGROUND
About a quarter of the stabilized sewage sludge produced by publicly ownedj
treatment worksj (POTW) in the United States is disposed of directly to thej
soil. Increasing restrictions on alternative sewage disposal practices andj
1 increased sludge production because of implementation of the Federal Water!
[Pollution Control Act Amendments of 1972 (PL 92-500) will result in greatlyi
\increas^djqujjntlties^of .^sewage^sjudge tieing appl_ied__to__the_land, furthermore,t
"it "is a valuable resource~~biec:ause" of^lts" nutrient and organic content, andl
: increasing emphasis will be placed on beneficial uses of sewage sludge simul-
taneously with land disposal practices for sewage sludge. The prospects ofj
.widespread 1 and'. application of sludge,-however, have caused increased concern;
;over possible-accumulation of toxic substances (e.g., heavy metals, pesticides;
|and other organics, and pathogens) in soils. The translocation of these toxicj
isubstances to growing crops, fodder used in silage, and to pastures is poorly!
:understood. Even less information is available on the translocation of thesei
;toxic substances throughout the direct food chain to animals and humans.j
'Another approach, then, is to use sewage sludge for the cultivation of non-food-]
.chain crops (NFCC). This beneficial use of the sludge could perhaps circumvent:
the problems associated with the unknown impacts of the toxic materials in the
;sludge on the food chain. I
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i The literature is replete with documented experiences on the application
[of sewage sludge to agricultural land, and there are some studies involving the!
[reclamation of .[disturbed lands (e.g.,I strip mine areas) with sewage sludge.j
'The data base for guidance concerning! application of sewage sludge to land!
icomes'from these studies. Pietz et al. (1) and the U.S. Department of!
;Agriculture (USDA) (2), as well as many others, have shown that it is technically!
'and economically feasible to land spread sewage sludge on agricultural and!
[disturbed land.; Therefore, it is worth considering the possibility that the!
production of NFCC is also technically [and economically feasible. If this werel
'found to be true, perhaps it would be possible to permit large-scale applica-j
tions of sewage.sludge to the land for[beneficial purposes without the concern!
[of increasing levels of toxics in the human food chain.
Objectives ,
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The primary;objectives of this study were to evaluate the feasibility and
[market potential for land application of sewage sludge for the cultivation of
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SECTION 2
CONCLUSIONS
The following conclusions have been made as a result of this study:
1. The non-food-chain crops (NFCC) with the best apparent feasibility for
production using sewage sludge are:
1. Softwoods amenable to monoculture operations
2. Forest nurseries
3. Horticultural specialties
4. Energy biomass trees
5. Oil crops such as cotton and soybeans
Though cotton and soybeans do not fit the definition of NFCC, it was felt
that the inedible products from these crops were sufficient to warrant .their
inclusion in this report.
2. Based on the criteria developed for this study, sod, cotton, and energy
biomass trees were selected as having the best apparent feasibility and
market potential.
3. Of the three crops considered, utilization of sludge for sod production
is the most feasible at this time. Sod production would use, conserva-
tively, 5% to 10% of the total sludge generated in the sod producing
states.
4. Based on only the three crops presented here, at least 20% of the total
sludge generated could be used for growing NFCC.
5. The variations in cost for sludge application among geographic regions
in the United States for the three crops examined are small compared to
variations based on the method of application and crop type.
6. The costs of sludge application to biomass trees and in some cases cotton
using the truck-spreading option compare favorably to the costsvfor com-
mercial fertilizer.
7. Transport costs for sludge can range from 1.5 to 7 times the cost of
sludge application for the cases studied based on a one-way transport
distance of up to sixty (60) miles transporting liquid sludge and sludge
cake. Transport costs vary between about $27/dry metric ton (DMT)
($25/dry ton (DT)) for sludge cake to $110/DMT ($100/DT) for liquid
sludge.
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8. Using sewage sludge for the production of NFCC could be the least costly
alternative for sludge disposal by a POTW, particularly if a cost benefit
is derived by also recovering damaged or upgrading non-productive land
to produce the NFFC.
9. To promote the use of sewage sludge for the production of NFCC, most of
the costs (transportation and application) associated with the use of
this material should be borne by the municipality generating the ma-
terial.
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SECTION 3
RECOMMENDATIONS
1. Research centered on the production of new and unusual crops such as the
: jojoba, euphorbia, and guayule should include the use of sewage sludge as
a source of nutrients or as a growing medium.
;2. Non-food-chain uses for cotton and soybeans are great, and these crops
have high N requirements. Thus a management system should be developed to
permit the use of sewage sludge for the cultivation of a portion of those
crops on a national basis. This management system would insure that those
"crops would not be used" for 'food-chain" products! ~~ " ~
'3. The costs for sludge application to NFCC should be studied in detail to
;. bring the comparison with commercial fertilizer into sharp focus. Good
cost estimates will assist in making the decision to use sludge on NFCC as
an alternative to commercial fertilizer or to enhance growth conditions.
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SECTION 4
FERTILIZER AND ENERGY VALUE |OF MUNICIPAL SEWAGE SLUDGE
INTRODUCTION : '.
The most common disposal technologies in use for POTW sludges are not based
.on the fact that this material is a recoverable resource, but that it is a spent
resource with no further value. However, new technologies are being developed
which emphasize' reuse of the minerals and organic matter present in POTW
sludges. As with any new technology, the benefits and drawbacks of the tech-
nology must be carefully.studied in order to make a determination of worth. It
has "been demonstrated" many timesthat the nutrient contenfof POTW "slutJges "can"
be used for crop production, and it has been suggested that these nutrients be
used to supplement that provided by chemical fertilization. The sludge also has
soil conditioner value. This suggestion has merit especially when the costs of
production of.the.nutrients are compared. -
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If POTW sludges can be used for plant production by supplying the adequate
nutrients necessary for growth, then the availability of this material should be
known and estimates of its nutrient value should also be known. In addition,
the value (both as a nutrient supplier and the economics of production and
application) of this material should be compared with the value of the primary
material most commonly in use. Once the above facts are known, then the user is
in a better position to determine the preferred product for use.
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This section gives an estimate of the quantities and nutrient value of POTW
sludges. Also, the quantities of chemical fertilizers that must be produced to
supply the plant nutrients present in POTW sludges were calculated for purposes
of looking at the energy costs involved.' Lastly, the amount of energy required
to chemically produce the nutrients contained in POTW sludges was compared with
the energy required to incinerate (destroy) these sludges. This was done to
explicitly show possible energy savings when beneficial POTW sludge usages are
considered. This information puts in perspective the nutrient value of POTW
sludge in relation to equivalent amounts of chemical fertilizer, the energy
needed to produce an equivalent amount of chemical fertilizer and the amount of
energy needed to destroy the sludge. Energy costs are discussed below.
QUANTITY OF SEWAGE SLUDGE GENERATED BY;POTW'S
National sludge production figures are difficult to estimate, but there
are many estimates given in the scientific literature. Dean (3) estimated the
actual national sludge production in 1972 to be approximately 9,072 DMT/d
(10,000 DT/d) and by 1990 the estimated quantity would be nearly 11,794 DMT/d:
(13,000_DT/d)_. The_CgunciJ__for Agrjcultural Science and Technology (CAST) (4)
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estimated municipal sludge production to be 8,115 DMT/d (8,945 DT/d) for 1970 and
that this would increase to 16,456 DMT/d (18,140 DT/d) by 1985. Thus, there are
considerable differences in the quantities of municipal sludge as estimated by
Dean and CAST.
The Water Resources Council (5) estimated that the sewered population in
1970 was 135 million (mil), while for 1985, 176 mil is projected. The estimate
was based on the U.S. population being served by sewers as 67% in 1970 and 75% in
1985. Farrell (6) estimated that the per capita daily raw sludge production was
0.055 Kg (0.12 Ib) for primary plants and.0.091 Kg (0.20 Ib) for primary and
secondary plants. The degree of treatment obviously impacted sludge produc-
tion.
If it is assumed that in 1970, 50% of the U.S. sewered population was
served only by primary and secondary plants and that the other 50% was served by
primary plants, then the annual sludge production would be 9,843 DMT/d (10,850
DT/d). For 1985, assuming that all municipal plants had primary and secondary
treatment, the annual sludge production would rise to 16,012 DMT/d (17,650
DT/d). The sludge production estimates used for these senarios are reasonable
when compared with the estimates given by Parrel! and CAST. ~
PLANT NUTRIENTS IN SEWAGE SLUDGE
Municipal sludge is derived from the organic and inorganic matter removed
from wastewater at sewage treatment plants. The amounts of the constituents
present will depend upon the wastewater sources and the method of wastewater and
sludge treatment.
Municipal sludge contains significant amounts of N, P, and K as well as
other plant nutrients. Table 1 shows the data of Zenz et_ jj]_. (7) and Sommers
et jj]_. (8). Zenz et _al_. (7) collected samples from 24 plants in the state of
TABLE 1. MAJOR PLANT NUTRIENTS PRESENT IN VARIOUS SEWAGE SLUDGE
SOURCES, PERCENT DRY WEIGHT
Constituent Illinois-24 cities (7) 7 States in the U.S. (8)
Total N
Ammonia Nitrogen
P
K
Range
2.6-9.8
0.1-6.1
0.7-4.9
Mean
5.4
1.8
2.4
Range
.03
.0005
.04
.008
- 17,6
- 6.7
- 6.1
- 1.9
Mean
3.2
0.7
1.8
0.3
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Illinois, while Sommers et a]_. (8) collected samples from plants in Wisconsin,-
Minnesota, Michigan, Ohio, New Jersey and New Hampshire. Sommers et &]_. (8)
collected over 180 samples for the N, P, and K data given in Table 1. As can be
seen, municipal sludge is a good source of N, P, and K, the major plant nu-
trients. The data collected by both Zenz^t jil_. (7) and Sommers jit ^1_. (8) was
for a variety of sludges from various wastewater and sludge treatment processes..
In general, municipal sludges havea total Ncontent pf_l%. to 6% .which is partly
in the inorganic form arid partly in the organic form (9, 10). Generally, 30% to
60% of the total nitrogen in anaerobically digested sludge is present as ammonia
nitrogen while the remainder is organic nitrogen (11). Phosphorus in sewage
sludge, as shown by the data of Zenz and Sommers ranges from about 1% to 6%. The
P in sewage sludge is generally considered to be as available to plants as the P
in chemical fertilizers (12). Potassium, as shown in the data from Sommers,
ranges from about 0.04% to 6.1%, but the mean is 1.8%. Because of the low levels of
K in municipal sludge, it is generally not considered a good source of this
nutrient. ,
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Plant Nutrient Levels in Various Sludges
As noted above, the data of Sommers and Zenz represented "a "broad "spectrlim"'
of various wastewater and sludge treatment processes. As such, the data show
the national picture of the nutrient content of municipal sludge. However, the
nutrient content will vary with the types of sludges which are produced by the
various sewage and sludge treatment processes. Although limited data are avail-
able, they are sufficient to indicate the relative levels of the plant nutrients
available.
Sommers (13) reported data on the N, P, and K levels of sludges from POTW's
using anaerobic digestion and aerobic digestion. These levels are given in
Table 2. As would be expected, the mode of digestion makes little difference in
the total levels of N, P and K, though the chemical state of the nutrients do
vary.
TABLE 2. N, P, AND K LEVELS IN ANAEROBIC AND AEROBIC DIGESTED SLUDGES
Type of sludge
Nutrient (%)
N
P
K
Anaerobic
4.2 ;
3.0 '
0.3 ;
Aerobic
4.8
2.7
0.4
Sommers et _al_. (14) also studied the effect of the wet air oxidation (WAO)
process on sewage sludge composition. Data were compiled on the plants before
and after treatment. The data are presented in Table 3. As can be seen, the WAO-
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process significantly reduced the soluble and particulate N. This would be
expected since ammonia nitrogen is sensitive to heat and will volatilize.
TABLE 3. NUTRIENT CONTENT OF SEWAGE SLUDGE BEFORE
AND AFTER WET AIR OXIDATION (14)
Constituent (%)
Soluble P
Particulate P
Soluble Total N
Soluble Organic N
Particulate Total N
Particulate Organic N !
Before
WAO
0.082
1.07
1.35
0.293
2.12
1.83
After
WAO
0.004
1.21
0.47
0.173
0.85
- 0.86
Lagoon ing of sludge also reduces the N content due to ammonia volatiliza-
tion and supernatant drawoff. Peterson et al. (15) compared the total N of
fresh digested sludge with that of sludge from lagoons having supernatant draw-
off. The data are given in Table 4.
TABLE 4. IMPACT OF LAGOONING ON THE NITROGEN CONTENT OF SLUDGE
Constituent (%). Digested sludge Lagooned
Total N 7.27 2.60
Ammonia Nitrogen 3.26 1.20
Heat drying will also cause a decrease in sludge ammonia nitrogen due to
volatilization. Peterson ert a.l_. (15) compared the level of total N and ammonia
nitrogen in sludge before and after heat drying. The data are given in Table 5.
Although total N remained unchanged, virtually all of the ammonia nitrogen was
volatilized by the heat drying process.
TABLE 5. NITROGEN CONTENT OF SLUDGE BEFORE AND AFTER HEAT DRYING
Constituent (%) Before After
Total N 6.7 ' 6.4
Ammonia Nitrogen 0.4 trace
8
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; ' Primary sludges~"appear""to have "characteristics similar ""tb"~those noted
above for the sludges studied by Sommers e_t jil_. (8). Manual of Practice No. ~
8 (MOP) of the Water Pollution Control Federation (WPCF) gives the values of
N, P, and K for primary sludges as shown in Table 6 (16). Waste-activated
sludge appears to have a somewhat higher N and P content than primary sludges.
;This is expected because activated sludge microorganisms utilize these con-
stituents in significant quantities. Anderson (17) summarized waste--
activated sludge, data from.both the Metropolitan Sanitary.District.of. Greater-
Chicago (MSDGC) and the Milwaukee Sewage Commission (MSC). The data are given
in Table 7. :
TABLE 6. N, P, AND K VALUES FOR PRIMARY SLUDGES
Constituent (%) Range Typical value
Total N.
Total P
Total K
1.5 - 4.0
0.35- 1.22
..../- 0.0 - 0.83
2.5
0.69
... '. . 0.29.
TABLE 7. NUTRIENT CONTENT OF TWO WASTE-ACTIVATED SLUDGES
Waste-activated Sludge
Constituents (%)
Total N
Total P
Total K
MSDGC
5.6
3.05
0.46
MSC
6.0
1.74
0.34
There is not an extensive amount of data available on the nutrient content
of trickling filter sludge and what is available is rather old. However,
Vesilind (18) reported that the N and P content of trickling filter sludge was
2.9% and 1.2%, respectively. This would indicate that the N and P content of
trickling filter sludge is relatively low when compared to that for waste
activated sludge.
Dewatering of sludges can result in changes in the nutrient content of
sludges. This occurs due to the removal of soluble components in the super-
natant, principally ammonia nitrogen, and in the case of vacuum filtration
using lime, by volatilization of ammonia gas. However, it is difficult to
generalize about the exact effect in any particular case. Zenz et al_. (19)
gives data on the N, P, and K content of dewatered sludges from anaerobic
idigesters using a centrifuge, a vacuum filter and belt filter press. The data
are given in Table 8. In general, the P and K content for all 3 units studied
were similiar. This was expected because those nutrients are not very soluble
in digested sludges and should not be affected even if the relative captures
9
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of the various dewatering techniques were somewhat different. The vacuum
filtered sludge had the lowest N concentration in its cake. This was probably
due to the lime addition and the resulting ammonia volatilization.
TABLE 8. NUTRIENT CONTENT OF VARIOUS DEWATERED SLUDGES
Constituent Centrifuge
% "Avg. Range
Total N
Total P
Total K
3.25
1.84
0.19
2.47
0.71
0.15
-4.15
- 3.13
- 0.21
Vacuum filter
Avg.
2.8 ,
1.6
0.12
Range
0.71
1.2
0.7
- 3.13
- 1.7
- 2.3
Belt filter press
Avg.
3.1
1.6
0.21
Range
2.2
1.2
0.14
- 3.8
- 1.7
- 34
Value of the Nutrients in Municipal Sewage Sludge
It is obvious from the above that municipal sewage sludge has significant
levels of N, P, and K which can be used for fertilizing crops. In this section
the amounts of N, P, and K contained in sewage sludge equivalent to that in
chemical fertilizers are computed and cost estimates for the sludge nutrients
are made based on current fertilier market prices for the nutrients. Costs
for N, P, and K were obtained from the International Mineral and Chemical
Company (20) as posted for January 21, 1980. The prices of inorganic N, P,
and K were $0.253/Kg ($0.115/lb), $1.37/Kg ($0.621/lb), and $0.259/Kg
($0.1176/lb), respectively.
As previously discussed, Sommers et al. (8) found that the mean N, P, and
K in seven states of the U.S. was 3.2^7" 1.8% and 0.3%, respectively. It was
also noted that a good estimate of U.S. sludge production for the years 1970
and 1985 is 9,843 DMT/d (10,850 DT/d) and 16,012 DMT/d (17,650 DT/d),
respectively. Using these data and costs for chemical fertilizer (20), Table
9 was constructed. The figures given are for daily sludge production. As can
TABLE 9. DAILY VALUE AND COSTS* OF NUTRIENTS CONTAINED IN MUNICIPAL SLUDGE
Year
1970
1985
MT
of
N/d
315
512
Cost of
N
($/d)
79,695
129,536
MT
of
P/d
177
288
Cost of
P
($/d)
242,490
394,560
MT
of
K/d
29
48
Cost of
K
($/d)
7,511
12,432
* Cost figures were derived using equivalent commercial fertilizer nutrient
values.
be seen, the total daily sludge production in the U.S., based on 1980 dollars,
has a chemical fertilizer equivalent market value of $537,000 for the year
10
-------
1985. Of course, municipal sewage sludge has benefits other than its nutrient
value. The organic matter present, for example, offers many benefits includ-
ing improvement in tilth and water holding capacity for sandy soils. However,
it is difficult to place a dollar value on sludge benefits other than its N,
P, and K value.
ENERGY REQUIREMENTS
Energy Required To Produce Nitrogen, Phosphorus and Potassium
The production of nearly all inorganic nitrogen fertilizers requires
energy. To produce inorganic N, N is combined with hydrogen under high tem-
peratures and pressures. The initial product is anhydrous ammonia which can
be used directly or converted to other forms of N such as ammonium nitrate.
Most of the hydrogen is obtained from natural gas, although other possible
sources are oil and coal. Obviously energy is also required for heat and to
operate the equipment used in the manufacturing process.
« The production of 0.9 MT (1 ton) of ammonia usually,requires about 1,080
MJ (38,140 ft3) of natural gas of which 630 MJ (22,248 ftj) is used as a source
of hydrogen and the remainder as a source of heat in the process (21). In
addition, 34 1 (9 gal) of fuel oil and 54 KW (72 hp) oi electricity are
usually used (21). The total energy requirement is 47.41x10 kJ/MT (10.27x10
Kcal/ton) of ammonia produced or 47,368 kJ/Kg (5,138 Kcals/lb) of N produced
(21). The conversion of ammonia to other nitrogen products requires addi-
tional energy.
As noted in Table 9, the daily amount of N available in municipal sewage
sludge was estimated to be 315 metric tons (347 tons) for 1970 and 512 metric
tons (564 tons) for 1985. This information, coupled with the fact that 3.8 1
(1 gal) of No. 4 fuel oil contains 152,408 kJ (144,452 Btu's) of energy and
that the January, 1980 cost (22) of this fuel oil was about $0.24/liter
($0.91/gal), was used to generate the data given in Table 10. The estimates
for the year 1985 were made using the current fuel costs, since fuel costs are
too dynamic to estimate what they would be in 1985.
.TABLE 10. COMPARISONS OF ENERGY REQUIREMENTS FOR THE
PRODUCTION OF INORGANIC NITROGEN
Year
1970
1985
N in
muni-
cipal
sludge
(MT/d)
315
512
Energy to
produce
equivalent
ammonia nitrogen
(KJ/d)
14.9 x 109
24.3 x 109
Quantity
of No. 4
fuel oil
to produce
ammonia nitrogen
0/d)
371,503
605,873
Cost of
fuel
S/MT of N
283.05
284.00 .
No. 4
oil
$/d
89,161
145,410
11
-------
Unlike N, P is not manufactured but is mined from deposits of naturally
occuring rock phosphate. Therefore, there is no energy per se required to
produce it except for the considerable energy required for mining and refin-
ing. The Mining Congress Journal reported that the total energy required to
produce 0.91 MT (1 ton) of elemental P is 182x10° kJ (172xl(r Btu's) (23).
With this information and the data on concentrations of P in municipal sludge
given in Table 9, the data shown in Table 11 were compiled.
'' TABLE 11. COMPARISONS OF ENERGY REQUIREMENTS FOR THE
PRODUCTION OF INORGANIC PHOSPHORUS
Year
1970
1985
P in
municipal
sludge
(MT/d)
177
288
Energy to
produce
equivalent P
(KJ/d)
35.4 x 109
57.6 x 109
Quantity of
No. 4 fuel
oil to pro-
duce P
(1/d)
882,631
1,436,145
Cost of
fuel
$/MT of P
1,197
1,197
No. 4
oil
$/iI
211,831
344,675
Potassium is mined from naturally occuring potash deposits. Energy
figures for the mining and refining of K^O were not available. However,
Heichel (24) reported that the "energy required for potash production is 40%
to 60% of the retail value of K^O". Therefore, although exact values were
not available for K?0 production energy requirements, approximately half the
retail value of inorganic K~0 can be assumed to be the cost of energy. Thus,
the data given in Table lz were developed using 50% of cost values for
inorganic K given in Table 9.
TABLE 12. COMPARISONS OF ENERGY REQUIREMENTS FOR THE
PRODUCTION OF INORGANIC POTASSIUM
Year
1970
1985
Metric tons
of K/day
29
48
Total retail
value
($/d)
7,511
12,432
Energy cost
($/d)
3,755
6,216
Equivalent
quantity
of No. 4
fuel oil
required
(1/d)
15,646
25,900
Energy Required To Incinerate Municipal Sewage Sludge
Sewage sludge incineration has been practiced for many years and es-.
sentially evolved from industrial technology developed during the 19th cen-
tury. It was an extremely attractive alternative during the earlier periods
of available cheap energy and minimal air pollution control requirements.
12
-------
However, due to the need for expensive air pollution control devices, the
need for large quantities of auxiliary fuel to evaporate excess water, and
the national energy crisis, the future for this sludge treatment process is
aleak.
The objective of an incineration system is to release heat from a fuel
(in this case municipal sludge) and to completely destroy all the volatile
elements. Sewage sludge is difficult to combust, because--it -is not'homo-
genous and it contains large quantities of water. Although the fuel content
of sludge is fairly high, 11,656 to 23,312 kJ/Kg dry solids (5,016 to 10,032 :
Btu/ Ib dry solids), the water content of most sludges requires the addition
of auxiliary fuel to maintain combustion (25).
Olexsey and Farrell (26) did a survey of auxiliary fuel consumption for
seven cities using sludge incineration in the United States with a total'
capacity of 384 MT/d (423 DT/d). The average auxiliary fuel consumption of
No. 2 fuel oil was 215 1/MT (51.6 gal/DT). For this report, this figure was
rounded to 200 1/MT (50 gal/ton) for a nationwide average. For purposes of
comparison, it was assumed that all of the municipal sludge produced in the
United States.was incinerated. - Based on. the national sludge production as
given previously, and converting No. 2 fuel oil to an equivalent amount of [
No. 4 fuel oil, the energy requirements and costs for sludge incineration on
a national basis might be as given in Table 13.
TABLE 13. ENERGY REQUIREMENTS AND COSTS FOR TOTAL MUNICIPAL
; SLUDGE INCINERATION
Total No. 2 fuel oil Equivalent No. 4 fuel
quantity requirements oil requirements
municipal
sludge '..
incinerated
in U.S.
Year (MT/d) (KL/d) ($/MT) ($/d) (KL/d) ($/MT) $/d
1970 9,843 1,969 48.69 479,256 1,998 48.72 479,551
j
1985 16,012 3,202 48.67 779,304 3,250 48.71 779,945
* No. 2 fuel oil has a heating value of 40,834 kJ/1 (146,500 Btu/gal). \
SUMMARY : - ; ' |
I i
The daily costs for producing equivalent chemical fertilizer nutrients-
from sewage sludge can be compared to the costs required to incinerate the '
sludges by comparing the sum of the values presented in Tables 10, 11 and 12
with the values presented in Table 13. This comparison indicates that the
daily costs for producing equivalent chemical fertilizer nutrients from
sewage sludge are less than that required to incinerate the sludges.
Furthermore, it seems that the destruction of the sludges is an unwise
allocation of a resource. The energy requirements needed to produce in-
organic N, P, and K and to destroy a source of N, P, and K are staggering. It
13
-------
is imperative that the scientific community seriously consider all resources
involved and that recommendations for beneficial resource allocations be
made. Energy is scarce and it is imperative that energy conservation be
paramount in the decison-making process for all new and emerging tech-
nologies.
14
-------
.SECTION 5
METHODOLOGY FOR SELECTION OF NON-FOOD-CHAIN CROPS
Food-chain crops are defined as (1) tobacco, (2) crops grown for human
consumption and (3) pasture, forage, and feed grain for animals whose products
are consumed by humans. Non-food-chain crops are, therefore, those crops that
remain. Thus NFCC in the strictest sense are those crops that are not
directly or indirectly consumed by humans.
This definition overlooks the possibility that at some time the land may
be used for the cultivation of food-chain crops. In that event, the same
criteria applicable to food-chain crops with respect to soil residues may also
apply to NFCC. This definition also disregards the entire concept of the food
web. Some crops could be grown for NFCC purposes, but due to uncontrollable
factors could be consumed in part by animals and/or fowl that may later be
consumed by man. For example, soybeans could be grown for non-food purposes,
but be consumed in part by foraging deer; these animals may then become food
for man. However, it is necessary that information in this area be developed
for use in the decision-making process.
Non-food-chain crops were selected based on the stated definition. These
crops were first identified by general category using the Standard Industrial
Classification (SIC) code (27). The code, however, did not include crops such
as sisal, jute, and hemp. These were added to this list of NFCC because they
clearly met the definition criteria, they require N and P for growth, and they
have a market potential. New crops that will have a market potential but are
still presently in the research stage (jojoba, euphorbia, guayule, and bio-
mass crops, for example) were added to the list. The possibility does exist
that these crops could obtain the necessary nutrients and essential elements
from sewage sludge for growth. A review of this list showed that there were
many potential NFCC that could be cultivated using sewage sludge as a source
of nutrients. Two food crops, cotton and soybeans, were added to list. These
crops were included for the following reasons: (a) data available indicated
that the inedible uses of these crops could be significant enough to warrant
further study; and (b) cotton clearly has a high N demand. In addition, both
crops respond favorably to commercial fertilization. The selected crop cate-
gories and SIC codes are given in Table 14.
15
-------
TABLE 14. CATEGORIES OF NON-FOOD-CHAIN CROPS SELECTED FOR STUDY
SIC SIC
Group no. Industry no.
081 0811 Timber tracts: Timber tracts
and tree farms (tree planta-
tions)
082 0821 Forest nurseries, tree
seed gathering, extracting
and setting
Oil 0119 Flax, flaxseed farms
018 0181 Horticulture specialities:
Ornamental floriculture
and nursery products
XXX XXXX Hemp, Jute, Sisal
XXX XXXX Miscellaneous (research
crops)
a. jojoba
b. guayule
c. euphorbia
d. energy biomass (woods
and herbs)
013 .0131 Cotton
Oil 0116 Soybeans
The selection of the most feasible NFCC suitable for cultivation using
sewage sludge, used for this study, was based on a developed set of criteria.
Liquid digested sludge, dewatered sludge and composted sludge are included in
the term "sewage sludge", unless otherwise noted. The criteria used are given
below.
1. Verification of crop as a non-food-chain crop.
2. High market potential, present and future.
3. Suitability for sludge application for crop cultivation.
4. Fertilizer requirements of the crop.
16
-------
5. Sensitivity to environmental factors:
Hardy
Climate tolerance
pH tolerance
Tolerance to metals
Tolerance to other sludge components
6. Minerals and metals needed for growth and productivity.
7. Additional amendments to sludge required for crop cultivation.
8. Crop rotation period and efficiency of crops for utilizing nutrients
in the sludge.
9. Economic crop size, acreage presently under cultivation, minimum
amount of sludge needed to support growth.
10. Documented research on the crop using sewage sludge for cultivation
of the crop; availability of data on growth and nutrients. ~ '
11. Proximity of the crop cultivation centers to sludge generation
centers.
12. Potential of sludge application to produce an imbalance in the eco-
system.
13. Dedication of land to permanent growth of NFCC.
The most important criteria for this study were:
1. The crops must not produce edible matter that could easily become a
part of man's food chain.
2. The crop must have a demonstrated or a high probability of future
market potential.
3. The land used to raise the crop must have a high probability of being
used continuously and exclusively for the production of that crop.
4. Data must be available that give the response of the crop to sewage
sludge, or sufficient data must be available for similar crops to
allow probable response determination using data extrapolation and
inference.
Twenty crops were initially studied using the above criteria. These crops
are given in Table 15.
17
-------
TABLE 15. POSSIBLE NON-FOOD-CHAIN CROPS AMENABLE TO CULTIVATION
USING SEWAGE SLUDGE
Crop category
Representative crops
Timber Tracts
Hardwoods:
Forest Nurseries
Flax, flaxseed farms
Horticulture Specialties
Research Crops
Oil Crops
Softwoods:
Aspen
Sycamore
Oak
Sweetgum
Cottonwood
Pine varieties
Douglas fir
Spruce
Those hardwoods and softwoods capable
of propagation by seedlings.
Flax :
Greenhouse varieties
Shrubs
Sod, turf grasses
Lawn grasses
Jojoba
Guayule
Euphorbia
Energy biomass (wood and herbs)
Cotton
Soybeans
The list of crops given in Table 15 was then reduced to six crops (or crop
categories) using the selection criteria. Those six crops appeared to be the
most promising non-food-chain crops. Of those six crops, three were selected
for an in-depth case study.
18
-------
.^SECTION 6 .
NON-FOOD-CHAIN CROPS AMENABLE TO
CULTIVATION USING SEWAGE SLUDGE
DISCUSSION OF POTENTIAL CROPS
Timber Tracts
Commercial timber consists primarily of pulpwood and sawtimber of various
species. The principal sawtimber species of the U.S. are the Douglas fir and
the ponderosa pine. .Based strictly on inherent productivity, oyer__98% of the
forest area in the northeast is capable of growing useable crops of "timber,',
and over half of all commercial timber!ands are. occupied by eastern hardwood
forest types. Softwood types make up approximately 42%, western hardwoods
approximately 3%, and nonstocked (cleared) areas approximately 4% of the
commercial timberlands. Approximately 202 x 10 ha (500 mil acres) of land in
the U.S. are devoted to commercial timber tracts, with 40.5 x 10 ha (100 mil
acres) being located in the National Forests (28).
Sewage sludge could be useful as a source of nutrients and as a soil
conditioner in situations where:
1. The establishment of tree plantations is desired.
2. The reforestation of clear-cut areas or forest fire devastated areas
is desired.
3. The production of seedlings is desired.
Tree plantations for commercial use are for the most part monocultures,
and thus could possibly serve as buffers to the movement of
sludge contaminants into the surrounding ecosystems and food webs. "Mono-
cultures", the growth of one species of plants to the exclusion of others,
provide very little variation of habitat or food as is required for healthy
(balanced) ecosystems. Therefore, the utilization of these monocultures for
food by "wild" populations of animals or fowl may be restricted resulting in
little effect upon surrounding ecosystems. These plantations tend to be
located in areas that are accessible"by truck or pipeline for sludge trans-
port. Also, they are located mainly in regions where production of the crop
is rapid, such as the southeastern U.S. Examples of tree crops grown in
plantations are the pine, spruce and fir trees for the production of pulp and
paper and for Christmas trees.
19
-------
Tree crops used for pulp and paper are normally fertilized only once at
the time of planting, and have a rotation period of 10 to 20 years. The
faster growing varieties with a rotation period of less than 20 years require
intensive cultivation and are not currently being used to any great extent by
industry because of growing costs. It is not a common practice to fertilize
Christmas trees since fertilization causes rapid growth and "leggy" trees.
Labor costs for pruning would outweigh benefits of quicker growth to saleable
size.
The nutrient requirements of forest trees are less well known than those
of agricultural crops. Forests are usually fertilized naturally, but the
external addition of nutrients and moisture can stimulate tree growth. The
external addition of nutrients and moisture could be economically beneficial
where poor soils exist. Generally, tree fertilization has been confined to
nurseries and orchards. The cost of fertilizing a forest could be expensive
and difficult to achieve due to inaccessibility of the sites; however, ferti-
lization by air is feasible. (Of course, this practice would preclude the
possibility of using sewage effluent or sewage sludge.) It has been suggested
that a forest be fertilized about once every five years, thereby increasing
yields by as much as 20% (29). It is not known if this increased volume of
timber would justify the cost. This would have to be determined on a case-by-
case basis. Fertilization of forests is presently being practiced in Sweden
and France. Finland plans to fertilize over 405,000 ha (one mil acres) to
increase yields (29). A forest in France is used as the site for the land
application of wastewater and sludge. The operation is quite successful in
terms of wastewater renovation and tree growth.
Hardwoods--
Forest timber tractsTable 16 lists the hardwoods grown in the U.S. The
annual nutrient uptake of hardwood forests is very low when compared with
agronomic crops. Table 17 gives the N, P, and K requirements for tree crops.
It is interesting to note that most of the N taken up by the tree is returned
to the soil during leaf fall. Hardwoods are not suitable for cultivation in
management-intensive situations if the wood is to be used for sawtimber.
Also, hardwood forests tend to be remote and accessibility to many of the
sites is difficult.
20
-------
TABLE 16. TYPES AND DISTRIBUTION OF DECIDUOUS TREES (HARDWOODS) IN THE UNITED STATES
Type of tree
Range
Major uses and
growth factors
1.
2.
ro
3.
Eastern Cottonwood
(Populus deltoides)
Plains Cottonwood
(Populus sargentii)
Tulip Poplar or Yellow
Poplar
(Liriodendron tulipifera)
New Hampshire to New York, central
Michigan, Wisconsin, central =
Minnesota south and west to North
Dakota, western Kansas, western
Oklahoma and central and south-
eastern Texas and east to north-
western Florida and Georgia.
Montana, Wyoming, eastern Colorado,
northeastern New Mexico, and north-
western and northern Texas and
north to western Oklahoma, Kansas,
Nebraska and western South Dakota.
Massachusetts and southern Vermont
to New York and southern Illinois,
southeastern Missouri, eastern
Arkansas and Louisiana and east to
central Florida. >
Pulp and Paper
Pulp and Paper I
Softwood, rapid^growth.
Reaches pulp size
in 15 years, saw timber
in 40-50 years.: Lumber
used in furniture
and home construction.
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
4.
Royal Paulownia or
Princess Tree
(Paulownia tomentosa)
5.
American Elm
(Ulmus americana)
ro
ro
6.
Black Ash
(Fraxinus nigra)
Cultivated and naturalized in
eastern U.S. from southern New
York to West Virginia, southern
Indiana, southern Illinois, and
eastern Missouri and south to
southern Texas and northern
Florida.
North Dakota, southeastern Montana,
western Nebraska, western Oklahoma
and central Texas, and east to
Florida.
Maine to northeastern North Dakota,
south to Iowa, Illinois, Indiana,
West Virginia, Maryland and
Delaware. Also, local in
northern Virginia.
Softwood, uses unknown,
will reach 20 cm to
25 cm (8-10 in)
in diameter in 10
years,seedingnaturally.
Native to China.
Will grow on many
soils but requires
additional water in
dry regions. Desired
soil pH 6.0-7.0.
Susceptible to dutch
elm disease. Source
of lumber.
Grows best in a slightly
acid, silt loam soil
and should be grown
only on moist sites.
Desired soil pH 6.0-
7.0. Source of lumber,
pulp and paper.
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
7.
Green Ash
(Fraxinus pennsylvanica)
8.
White Ash
(Fraxinus americana)
ro
CO
9.
Ailanthus, Tree-of-Heaven
(Ailanthus altissima)
From Maine to Montana, northeastern
Wyoming, northeastern Colorado and
Kansas to central Texas, and east_
to northwestern Florida and Georgia.
Maine to northern Michigan and
southeastern Minnesota, south ito
eastern Nebraska, eastern Texas
and east to northern Florida.
Cultivated and widely naturalized .
as a "weed" tree from Massachusetts
to Iowa and Kansas, south to
southern Texas and Florida and
established to a lesser extent in
western U.S. from southern
Rocky Mountains to Pacific states.
Grows on relatively
dry sites and is tolerant
of 'alkaline soil.
Desires soil pH;6.0-
7.0. Wood for tools,
pulp and paper.:
(
It is moderate to
fast growing and grows
well on many soil
types. Desired soil
pH 6.0-7.0. Wood
for tools, pulp; and
paper. :
A fast growing tree,
most rapidly growing
woody plant in U.S.
Will thrive under
extremely adverse
conditions, growing
as much as 2.44 M/yr
(8 ft/yr). Annual
sprouts 3.66 M (12
ft) long not uncommon
where tree has been
cut down. Immune
to dust and smoke
and may grow to a
large size. Softwood
has some lumber: and
fuel^talue. :
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
10. White Oak
(Quercus phellos)
11.
Yellow Oak
(Quercus muehlenbergii)
rsj
12.
Black Oak
(Quercus velutina)
Central Maine to Michigan and
Minnesota, south to Iowa, eastern
Kansas and eastern Texas, and
east to northwestern Florida and
Georgia.
Vermont and New York, west to
southern Michigan, southern
Wisconsin and southeastern
Nebraska, south to western
Oklahoma, central and eastern
Texas, east to northwestern
Florida and Georgia, and
north in mountains to Maryland
and to western Connecticut.
Southwestern Maine to New York,
Michigan, Wisconsin, southwestern
Minnesota and southeastern
Nebraska, south to eastern Texas,
northwestern Florida and Georgia.
A relatively fast
growing hardwood which
will grow on a variety
of soils. Desired
soil pH 5.0-6.0.
Sources of lumber.
Lumber.
Grows at a moderate
rate and will grow
on a wide range of
soils. Source of
lumber.
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
13. Pin Oak
(Quercus polustris)
14.-
Post Oak
(Quercus stellata)
ro
01
15.
Quaking Aspen
(Populus tremuloides)
Massachusetts and southern New'
York to Pennsylvania, southern;
Michigan, northern Illinois,
southeastern Iowa, and eastern
Kansas, south to northeastern .
Oklahoma, northern Arkansas, ,
Tennessee and South Carolina. :
Local in southern New England
from southeastern Masschusetts
to southeastern New York, :
southeastern Pennsylvania, West
Virginia, Ohio, central Illinois,
and southern Iowa, south to
eastern Kansas, western Oklahoma
and central Texas and east to
northern Florida. ;
i
High mountains of western U.S. !
from Washington south to j
southern California, Arizona,
New Mexico and sections of ;
Texas, and north to Colorado, j
northwestern Nebraska, South
Dakota and Montana, south in
northeastern U.S. from northern
and eastern North Dakota, extreme
South Dakota, Iowa, Illinois,
Ohio, West Virginia, Pennsylvania,
New Jersey and Maine.
Grows relatively rapidly
for a hardwood on
a wide range of soils,
but becomes chlorotic
on alkaline soil.
Source of lumber.
Grows at a moderate
rate on many soil
types. Source of
lumber.
Wood for tools, pulp
and paper. :
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
16. Pignut Hickory
(Carya glabra)
ro
17. Bitternut Hickory
(Carya cordiformis)
18. White Birch
(Betula alba, popyrifera)
19. Sugar Maple
(Acer saccharum)
Southern New Hampshire and
Massachusetts, west to New York,
southern Michigan, Illinois
and northeastern Kansas, south
to southwestern Oklahoma and east
to Arkansas, Mississippi,
northwestern Florida and Georgia.
New Hampshire to New York, Michigan
and Minnesota, south to southeastern
Nebraska and eastern Texas and east
to northwestern Florida and Georgia.
North Dakota, Minnesota and north-
eastern Iowa, and east to northern
Illinois, Michigan, Pennsylvania,
New York and New England.
Northeastern U.S. to 'Minnesota,
south to Iowa, eastern Kansas,
Oklahoma and northeastern Texas,
east to Louisiana and northern
Georgia and north to Virginia
and New Jersey.
Grows at a slow to
moderate rate and
is adaptable to many
soils, including
dry sites. Sources
of lumber.
Lumber.
Lumber.
Grows moderately fast.
Grows best on fertile,
well-drained soil.
Desires soil pH 6.0-
7.0.
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and i
growth factors I
,,^-. .20, .-.Silver. Maple- _ ..
\ (Acer saccharinum)
ro..:c...
21. American Beech
(Fagus grandifolia)
22. . Sweetgum
(liquidambar styraciflua)
» ^f
,Maine .to Michigan and.Minnesota, .
south to southeastern South Dakota,
eastern Nebraska and eastern '
Oklahoma, and east to Mississippi
and Georgia. ,>.
I
Maine to northern Michigan and
eastern Wisconsin, south to J
southern Illinois, southeastern
Missouri, northwestern |
Arkansas, southeastern Oklahoma,
and eastern Texas and east to i
northern Florida. )
Connecticut and southeastern I
New York, to Virginia, West i
Virginia, southern Ohio,
southern Illinois, south- |
eastern Missouri, Arkansas i
and southeastern Oklahoma, '
south to eastern Texas and !
central Florida. I
»
.Grows..rapidly .op ..a,.
wide range of soils,
tolerates mild jsoil
alkalinity. Desired
soil pH 6.0-7.0!.
Sources of lumber.
Grows at a moderate rate
on many different
soils including!
limestone soil.)
Desired pH 6.0-7.0.
"Sources "of lumber/"
Grows rapidly on moist,
but well-drained soil.
Desired soil pH;6.0-
7.0. Lumber, pulp and
paper. j
(continued)
-------
TABLE 16. (continued)
Type of tree
Range
Major uses and
growth factors
23.
24.
Black Locust
(Robinia pseudoacocia)
Red Alder
(Alnus rubra)
Native of Appalachian Mountains
from Pennsylvania to northern
Alabama and in Ozark Mountains of
southern Missouri, Arkansas and
eastern Oklahoma. Extensively
naturalized in eastern half of
United States.
Pacific coast region from Washington
and western Oregon to southern
California.
Grows relatively rapidly
on a variety of soils.
Desired soil pH 6.0-
7.0. Sources of lumber.
Adds humus and nitrogen
to the soil. Wood used
for fuel, furniture,
veneers and paper pulp.
ro
oo
-------
TABLE 17. NUTRIENT REQUIREMENTS FOR A CONVENTIONAL FOREST AND NUTRIENT APPLICATION RATES FOR
FOREST CROPS
ro
Type of crop DMTE/hectare per year* Rotation
(yrs)
Conventional forest 3.14 - 6.05 30-80
Pulp plantation 12.33 10
Wastewater i rri gated
forest
Biomass tree farm + 18 6
Biomass tree farm + 18 6
Biomass tree farm +18 6
Fertilization
(kg/hectare
per year)
N . P K
66. 9 80
168 90 0
233 98 2 12
112 48 160
117 233 233
244 130
Reference '
Sopper and
Kardos (30)
Salo, D.J.,
J.F. Henery
R.E., Inman
(31)
Sopper and
Kardos (30)
Inman, Salo,
and McGurk,J.
(32)
Inman, Salo,
and McGurk.J.
(32)
Inman, Salo,
and McGurk.J.
. (32)
continued
-------
TABLE 17. (continued)
CO
o
Type of crop DMTE/hectare per year* Rotation Fertilization Reference
(yrs) (kg/hectare
per year)
Biomass farms
(Hardwoods)
Wisconsin 11
Missouri 16
Georgia 18
Illinois 18
New England . 11
; Washington 22
Biomass farm 11
Wastewater application
i to a forest +
N P K
Inman, Salo,
and McGurk,
J. (32)
6 64.5 12.3 69.3
6 90.3 17.0 97.60
6 103.2 19.6 111.1
6 103.2 19.6 111.1
6 64.5 12.3 69.3
6 129 24.2 139.3
112 - - Zavitkowski
(33)
- : 90-112 - - Environ-
mental
: : Protection
Agency (34)
(continued)
-------
TABLE 17. (continued)
Type of crop
DMTE/hectare per year*
Rotation
(yrs)
Fertilization
(kg/hectare
N
K
Reference
Experimental applications
to a forest
^ottonwood seedlings
112-224 67-112
224
168
224
Kitzmiller
(35)
Bonner &
Broadfoot
(36)
Dry metric ton equivalent/hectare per year = metric ton/hectare per year.
+ Estimated application of NPK for given productivity by various methods.
$ EPA design rate of wastewater application to forest land.
-------
Research by Sopper (37) and Kenady (38) indicates that the introduction
of sewage effluent and sewage sludge alters the forest environments drasti-
cally. Sopper reported that the understory vegetation that was present
initially had all but disappeared after 10 years of land application of
sewage effluent, and was replaced by more tolerant species. Kenady found
that the response of vegetative growth to the added nutrients was signi-
ficant. The increased vegetative growth served as shelter and food for
herbivores and carnivores and thus their populations increased tremendously.
It also appears that the vegetation that grew well in response to the added
nutrients was not a preferred source of food for the increased herbivore
population. As a consequence, the animals girdled the test tree seedlings
being studied by Kenady and caused wholesale mortality to the seedlings.
Studies by Sopper (37) and Urie (39) have demonstrated that some hardwood
forest stands respond favorably to liquid and dewatered sewage sludge appli-
cations and to sewage irrigation with no signs of phytotoxicity.
The forest is a very delicate ecosystem, and environmental control is
difficult. It is next to impossible to operate forest timber tracts as mono-
cultures. Any introduction of nutrients will stimulate herbaceous growth
which can serve as food for some of the animals that are a part of man's food
chain. Thus, in terms of the definition of a. non-food-chain crop, the usual
forest crops that could be classified as non-food-chain crops should not be
considered. Only those timber tracts that can be easily controlled should be
considered for sludge applications.
The reforestation of clear-cut areas using sewage sludge could present a
problem in that it is difficult to control competing vegetation and her-
bivores which could be detrimental to the desired tree crop (38). The
external addition of nutrients will stimulate the growth of the understory as
well as tree growth. Also, many clear-cut areas are remote, and the sites
would have at best intermittent availability for sludge application. Forest
fire devastated areas could also present similar problems.
Biomass productionOptimum biomass production for energy is dependent
upon rapid establishment and early utilization of the growing capacity of the
site. Optimized conditions for nutrients, water and tree growing space will
be required for maximum yield. It has been estimated that 5.4 to 26.3 DMT of
biomass/ha/yr (2.4 to 11.7 DT/acre/yr) can be obtained from a close-spaced
(120 cm x -120 cm) plantation operating on a rotation period of six years
(40).
Cottonwood, sweetgum, hybrid poplar, yellow poplar and sycamore have
been studied for biomass production using municipal wastewater and waste
heat (41). A close-spaced (0.9M of growth space per tree) hybrid poplar
plantation fertilized with sewage effluent yielded 75.9 DMT/ha (33.9 -
DT/acre) of biomass after a 5-year growing period. The control plot (no
sewage irrigation) yielded 25.8 DMT/ha (11.5 DT/acre) at the end of the 5-
year growing period. Even though the survival rate (57%) for the wastewater
irrigated plot was much lower than the control survival rate (87%), the
wastewater irrigated plot resulted in increased viable biomass yields of 93%
over the viable yields of the control plot.
32
-------
In another part of the study using both wastewater irrigation and waste.
heat, Sopper reported that after a year of growth, yellow poplar, cottonwood
and hybrid poplar exhibited a greater mean height in plots receiving waste-
water irrigation only. The sycamore and sweetgum had greater height growth in
areas which were only irrigated or held as controls.
Another significant point established by this work is that the greater"
biomass yields were obtained on those plots that had the closest'spacing."" In
fact it was shown that for each study, biomass production was inversely
related to growing space, even though the. greatest mortality occurred in the
high density plots. A possible cause for the higher mortality in the waste-
water irrigated plots was attributed to stimulated herbaceous vegetative
growth, which provided a more favorable habitat for mice and rabbits. This
was the same reason given by Kenady for the high seedling mortality rate
experienced in his work (38). The very close tree spacing will prevent the
passage of sunlight needed by the understory for photosynthesis; thus under-
story growth is inhibited. This further supports the idea of tree mono-
cultures, rather than the use of the open forests.
Fiber productionA point often discussed among foresters is-the-change
in the specific gravity of wood due to tree fertilization. Einsphar et al.
(42) reported significantly lower specific gravities for aspens grown on
irrigated and fertilized plots. Mitchell (43) concluded that the growth rate
of hardwoods increased in the presence of N and that there was a positive
trend toward increasing specific gravity with increasing growth rate.
Saucier and Ike-(44) .found no change in tissue composition of sycamore due to
fertilization. Murphy et_ al. (45) reported positive changes in red pine
wood and red oak wood due to sewage effluent irrigation of these stands.
The wood fibers were altered (specific gravity increased, percent latewood
increased) and the utilization of these wood fibers as raw material for
pulp and paper is enhanced.
It appears that the increased growth rate due to fertilization alters the
properties of the wood in established stands. An increase in the specific
gravity indicates an increase in the mass of fiber per unit volume. The
increased fiber content of the wood makes it a more desirable pulpwood.
Mitchell (43) found that red oaks responded favorably to irrigation using
sewage effluent at a rate of 5 cm (2 in) per week. The specific gravity,
percent latewood, and cell dimension changes in the trees were considered plus
factors in the utility of the wood for pulp.
Softwoods
Forest timber tractsTable 18 lists the coniferous trees grown in the
U.S. Softwoods constitute about 42% of the net sawtimber volume on commercial
forestlands, with the Douglas fir, ponderosa pine, spruces, and eastern white
and red pines being the most important softwoods. The Douglas fir constitutes
by far the greatest timber reserve in the U.S. The Douglas fir becomes desir-
able for its lumber at heights of approximately 30.5 M (100 ft). This is
achievable on good sites in fifty years, but this growth usually requires a
period ranging from 60 to 100 years. Pulpwood can be obtained in about 20
years from softwoods in the southeast.
33
-------
TABLE 18. TYPES AND DISTRIBUTION OF CONIFEROUS TREES (SOFTWOODS) IN THE UNITED STATES
Type of tree
Range
Major uses and growth factors
1. Longleaf Pine
(Pinus palustris)
2. Shortleaf Pine
(Pinus echinata)
3. Loblolly Pine
(Pinus taeda)
Coastal Plain from southeastern
Virginia to central Florida and
west to eastern Texas.
From northern Florida through
the Gulf States to Texas and
Arkansas and north on the pied-
mont and coastal plain from
Georgia to Virginia and on the
Delaware peninsula.
Eastern Texas and southern
Arkansas to central Florida
and north on the piedmont and
coastal plain through the
Carolina's to tidewater Virginia,
the Delaware peninsula and 'Cape
May, New Jersey.
Lumber, pulp and paper. Needs adequate
moisture, secondarily concerned with soil
texture or chemical composition. Where
soil moisture is limiting, its growth is
inhibited. Requires good drainage for
best growth and will grow on a wide
range of soils. Desired soil pH 5.5-6.5.
Lumber, pulp and paper. Closely associ-
ated with loblolly pine throughout most
of the inland or upper portions of the
Gulf Coastal Plain. Requires well-
drained soils with a desired pH 5.5-6.5.
Lumber, pulp and paper. Prefers wet
sites, attaining maximum growth on poorly
drained, moisture-holding clays and clay
loams, and often displays its best devel-
opment on the edges of swampy areas.
Will grow on a wide range of soils. De-
sired pH 5.5-6.5.
continued
-------
TABLE 18. (continued)
Type of tree
Range
Major uses and growth factors
tx>
4. Slash Pine
(Pinus caribaea)
(elliotti)
5. Pond Pine
(Pinus serotina)
6. Ponderosa Pine
: (Pinus ponderosa)
Coastal Plain from southeastern
Carolina to central Florida and
southeastern Louisiana.
Coastal Plain from southern New
Jersey and southeastern Virginia,
south to central and northwestern
Florida and Alabama.
Widely distributed, chiefly in
the Rocky Mountains and mountains
of Pacific Coast region from
southwestern North Dakota and
Montana, Washington and Oregon
to southern California, east to
Arizona and Texas, north to New
Mexico, Colorado, western
Nebraska and Black Hills of
South Dakota.
Lumber, pulp and paper. Found naturally
in the drainage of Coastal Plain longTeaf
forests east of the Mississippi River, in
the moderately-drained flatwoods of the ;
southeast. Will grow on a wide range of j
soils. Desired soil pH 5.5-6.5. ' \
; | i
i '.
Pulp and paper. '
Lumber.
continued
-------
TABLE 18. (continued)
Type of tree
Range
Major uses and growth factors
CO
CTV
7. Lodgepole Pine
(Pinus contorta)
8. Jack Pine
(Pinus banksiana)
9. White Pine
(Pinus strobus)
10. Douglas Fir
(Pseudotsuga
menziesii)
Western United States from
Washington to southern
California and western Nevada
and from Idaho and central
Montana south to Wyoming,
northern Utah and Colorado.
Great Lakes states of
Minnesota, Wisconsin,
Michigan, and locally
plentiful in Maine, north-
ern Illinois, northwestern
Indiana, northern New York,
Vermont and New Hampshire.
Minnesota, northeastern
Iowa, northern Illinois,
northwestern Indiana, Ohio,
Pennsylvania and New Jersey,
and south in the mountains
to western North Carolina,
northern Georgia and Tennessee.
Pacific coast region from
western Washington and Oregon
to central coastal California
and central Nevada.
Lumber
Pulp and paper. Normally occurs in
drier sandy soils. Over half the volume
of growing stock is found in Maine
where it develops best. Higher soil
nutrient levels in that state are
responsible.
Lumber, pulp and paper. Occupies sites
having a wide range of moisture and
nutrients. It requires better site
quality for optimum development
than other native pines.
Timber, reforestation and ornamental
Christmas trees and lumber. Grows
rapidly. Does best on sandy to silt
loam and tolerates alkaline soil.
Desired soil pH 5.0-6.0.
continued
-------
TABLE 18. (continued)
Type of tree
Range
Major uses and growth factors
CO
11. Balsam Fir
(Abies balsamia)
12. Englemann Spruce
(Picea engelmannii)
13. Blue Spruce'
(Picea pungens)
14. Red Spruce
(Picea rubens)
Minnesota, Wisconsin, Michigan,
northern Pennsylvania, New York
and New England.
Mountains of western United
States from Washington to
northern California, eastern
and southeastern Nevada, south-
eastern Arizona and southern New
Mexico and north to central
Colorado and central Montana.
Rocky Mountains region in .high
mountains from western Wyoming
and southeastern Idaho south to
Utah, northern and eastern
Arizona, New Mexico and central
Colorado.
Maine south to eastern New York,
northeastern Pennsylvania and
northern New Jersey. Also, south
in Appalachian Mountains of
western Virginia, western Maryland,
West Virginia, western North
Carolina and eastern Tennessee.
Lumber and popular Christmas trees.
Grows best in moist soils.
Lumber.
Lumber. Grows best on well-drained
soils with pH 5.0-6.0.
Lumber. Grows best on well-drained
soils in the highlands withpH 5.0-6.0.
continued
-------
TABLE 18. (continued)
Type of tree Range Major uses and growth factors
15. Western Red Cedar Pacific Coast region from western Lumber.
(Thuja plicata) Washington and Oregon to north-
. western California. Also, east- ,
ward in Rocky Mountains from
eastern Washington, northern
Idaho and western Montana.
CO
-------
Trees for pulp are quite frequently produced in plantations or mono-
cultures. Monoculture.operations appear to be suitable for sewage sludge
applications. Data in the literature indicate that the softwoods do respond
favorably to fertilization using sewage effluents and sludge (45, 46).
Zasoski et al. (46) found that sludge applications of 112 and 224 DMT/ha
(50 and 100 DT/acre) to a Douglas fir forest caused an unidentified toxicity. At
sludge concentrations of 22.4 and 45 DMT/ha (10 and/20 DT/acre), the 10 and 20
year old plots of Douglas fir showed a growth increase. - --
The presence of the nutrients added to the soil by the sewage will stimu-
late herbaceous growth. Because this growth may adversely affect tree growth,
cultural treatments may be required if the tree spacing is too wide. Close
tree spacing may reduce the number of cultural treatments, but the close
spacing on the other hand might restrict the use of sewage sludge applica-
tions. Thus, these close spacing operations maybe more amenable to sewage
irrigation rather than sewage sludge application.
Biomass productionEnergy farms, as presently being studied, consist of
rapidly growing tree species that are capable of growing by coppicing (sprout-
ing from stumps). Conifers, with the exception of the redwoods,-do not
coppice, and are somewhat slow in establishing growth; thus tree biomass
production has been centered primarily around the hardwood species. However,
the loblolly pine does meet most of the criteria for candidate biomass
.species.
Fiber production-Trees grown for fiber only do not have to meet the same
requirements as trees grown for sawtimber. In fact, when fertilized, these
trees may produce more fiber per unit volume, and research has shown that
fertilization of forest trees tends to produce a tree with more desirable
pulpwood properties (43).
The more conventional tree plantations operate on a 30 to 80 year rotation
period, but several of the commercial paper industries are experimenting with
trees that have a rotation period of 8 to 15 years. Plantations that are
operated using these fast rotation periods are management-intensive and cost-
ly. However, it appears that these plantations could benefit from the addi-
tion of sewage sludge for the restoration of nutrients. If close-space
planting is practiced, weeds and other herbaceous growths could be reduced
considerably. Tree growth rate increases of up to 100% using sewage irriga-
tion have been reported (45). However, whether the increase in fiber volume
would be significant enough to offset the cost of the operation is not known.
Summary
A list of some of the fast growing tree species and their market uses
are given below.
1. Pines (Pinus sp) - native species, pulp size in 15 years, timber in 20-30
years. Procedures for cultivation presently developed..
39
-------
2. Tulip Poplar (Liriodendron sp) - native spec.ies. Reaches pulp size in 15
years, sawtimber in 40-50 years.
3. Black Locust (Robinia sp) - native. Pulp and fence-post size in 15-20
years; resprouts after cutting.
4. Ashes (Fraxinus spp) - native species. Pulp size in 20 years; sawtimber
in 50 years. .
5. Poplar Hybrids (Populus.spp) - softwood, rapid growth.
6. Empress Tree (Paulawnia tomentosa) - from China. Wood soft; uses unknown;
will reach 8-10 inches in diameter in 10 years; seeding naturally.
7. Tree-of-Heaven (Ailanthus) - from Asia. Widely established along road-
sides and forest edges. Rapid growth; root sprouts. Should give a crop
of pulpwood every 15 or 20 years.
Any of the hardwoods and softwoods amenable to plantation growth or to
growth under intensive management practices could be cultivated using sewage
sludge as a fertilizer. However, the application of sewage sludge is more
easily achieved on normally-spaced plantations. This spacing practice would
allow a greater proliferation of herbaceous growth, and thus cultural treat-
ments for the control of weed growth would be required. On the other hand,
closer spacing would tend to inhibit understory growth, but this would also
decrease the ease with which sewage sludge could be applied.
The above information does show that sewage sludge could be used as a
source of nutrients for the cultivation of the following timber tracts:
1. Softwoods grown in monoculture operations for the production of
pulpwood and other wood byproducts.
2. Softwoods that reach maturity in 10-20 years.
Forest Nurseries
The production of tree seedlings using sewage sludge is very promising.
Forest seedlings are fertilized and have a rotation period of 6 months to 2
years. The seedlings are usually produced under controlled conditions and,
thus, would have minimal impacts on the forest ecosystem or food web.
Gouin et^ al. (47) reported that the Norway spruce and white pine seed-
lings grew well on composted sewage sludge. He also found that an application
rate of 224 MT/ha (100 tons/acre) was sufficient to yield two crops of decid-
uous seedlings over a four and one half year period. Kenady (38), working in
the open forest environment, found variable response to dewatered sludge by
softwood seedlings. He accounted for the variation in response based on
seedling acceptability of, or tolerance to, the sludge and to competing vege-
tation that developed on the growing sites.
40
-------
In terms of seedling response to dewatered sludge, Kenady ranked the
Douglas fir as the best, and the Sitka spruce, ponderosa pine and western
hemlock as two, three and four, respectively.
The Forest Service reports that there are approximately 170 forest tree
nurseries in the U.S. (48). These nurseries are both bareroot and container.
operations. The bareroot operations have approximately 4,050 .ha (10,.007.._
acres) available for production and the container operations add another 16.2
ha (40 acres) to this production capacity. In 1976 over one billion seedlings
were grown for forest and windbarrier plantings. This industry is in a prime
position to utilize sewage sludge as a source of fertilizer and as a soil
conditioner for the production of crops.
8
Most of the seedlings produced in Federal nurseries (1.1 x 10 in 1976)
are planted on National Forest lands. The seedlings producedgin forest
industry nurseries are generally planted on company lands (396 x 10 seedlings
in 1976), but some of these seedlings are distributed to other private land-
owners (49). Reforestation projects annually involve over 700,000 ha (1.73
mil/acres). Special purpose plantings, which include a) recently cutover land,
b) plantings exclusively for Christmas trees, c) plantings for surface mine
reclamation, and d) plantings for wildlife purposes, are included in the
reforestation projects. Forest industries (pulp, timber, etc.) alone planted
421,000 ha (1.04 mil acres)in 1976.
Gouin et aT_. (47) has shown that deciduous and coniferous seedlings grow
very well Tn composted sludge amended plots. Their work supports that of
Berry and Marx (50) and it thus appears that the optimum soil application
levels of the composted sludge for the production of seedlings are in the
range of 112 to 224 MT/ha (50 to 100 tons/acre).
Kenady (31) studied the response of coniferous seedlings to sewage
sludge. He reported a variable response among the seedlings, and attributed,
the variation to seedling species, the tolerance of the seedlings to the
sludge characteristics, and to the competing vegetation that developed on the
planting sites. Kenady used dewatered sludge application rates ranging from
10 cm to 15 cm per year. The species recommended for planting in sludge,
based on his data, are the Douglas fir, Sitka spruce, ponderosa pine and western
hemlock, in that order.
Summary-
Forest seedlings established in container operations or in plantation
style bareroot operations using sewage sludge have been shown to be equal to
and even superior in quality and quantity to seedlings established using
standard fertilizers. Sewage sludge can replace the nutrients removed from
the soil when the seedlings are extracted, and the sludge can be used to keep
the soils productive and thus can be substituted for green manure or peat-
moss.
The use of sewage sludge for these crops would reduce the possibility of
food chain health risks considerably - the crops produced are inedible and the
41
-------
soil containing many of the residues of concern is removed with the plant.
Thus, the risks associated with using the land for other purposes at some
future time are also minimized.
Flax and Flaxseed
"- ' »
Flax is one of the twenty principal crops planted in the U.S. (51). As
of 1974, 809,400 ha (2 mil acres) were under cultivation for the production
of this crop. It is best adapted to medium loam or clay soils, but grows best
in well-drained sandy loam soils in temperate climates. In most areas,
planting of the same land with flax is limited to once every six years to
avoid soil exhaustion. If planted with greater frequency, heavy appli-
cations of fertilizer are required. The usual practice is not to fertilize a
flax crop, but when it is necessary, N and P are the nutrients required.
Crop yields of approximately 1.4 M (40 bushels) are obtained on 0.405 ha (1
acre). Nutrient requirements per ha are approximately 23 Kg (50 Ibs) of N,
11 Kg (25 Ibs) of P as P205 and 7 Kg (15 Ibs) of K as K20 (51).
There are no reported studies on the response of flax to cultivation
using sewage sludge. However, soil that supports wheat, rye and soybeans
will also support flax. There are documented studies by Sopper and Kardos
(32) on wheat and by Hinesly (52) on soybeans that show that these crops
respond favorably to sewage sludge. Increased yields were obtained in each
case and these crops were quite efficient in removing the nutrients applied
to the sites in the sludge. Thus it can be assumed that flax grown under the
same conditions would show similar responses.
Sludge application for flax seed production may be beneficial in supply-
ing this crop with the relatively high nitrogen requirements. Studies on the
growth of flax have shown that flax grown on soils with a high N content have
a low fiber content. However, the market for linen has declined due to an
increase in the use of polyesters, and because the linen industry is very
labor intensive. Therefore flax is not usually grown for fiber production in
the United States. Flax seed is grown in the U.S. A market does exist for
linseed oil which is used for the production of paints, varnishes, linoleum
and oil-cloth.
Horticulture (Environmental) Specialties
The horticulture specialties show great potential for cultivation using
sewage sludge. In fact, the industry could profit from the use of sewage
sludge in light of the increasing costs of commercial fertilizers.
Nutrient requirements for the horticulture specialties, which include
both NFCC varieties as well as food-chain varieties, do not vary for each
kind of plant or species, rather only for the three major classes of plants.
Although vegetables are one of the three major plant species, they are not
being considered in this study. The remaining two major plant species are:
1. Small Decorative Flowering Plants
a. perennials
42
-------
b. bulbs
c. annuals
These plants require twice as much P and K than N. Too much N stimulates
leaf, and hence top growth at the expense of the flowers wanted. Phosphorus
produces flowers and strong roots, and K produces strong stems and vigor in
roots. The recommended commercial fertilizers have NPK ratios of 5-10-10 or
5-9-7. Liquid sewage sludge has an approximate NPK ratio of 1-1-0, and
composted sewage sludge has approximately the same NPK ratio as liquid sewage
sludge, with nitrogen being reduced by about two-thirds.
2. Wood plants
a. trees
b. shrubs
c. climbers
d. hedges
These plants need more N than P or K due to more leaves and hence the need
for more chlorophyll.
Studies by Kirkham (53, 54) under greenhouse conditions on tulips and
chrysanthemums showed that these flowers grew well when fertilized with
liquid sludge as the only nutrient source. There were no significant dif-
ferences in the growth and health of tulips grown with tap water, primary
effluent or organic liquid sludge. The tulips grown with dried organic
sludge produced buds, but did not open by the end of the experiment (20
days). She concluded that the tulips grew better with liquid sludge than
dried sludge, and that this could indicate that more sludge could be applied
on the surface of the soil than could be mixed or injected into the soil. The
data also indicated that the high soluble salt levels in soils treated with
organic sludges could be harmful to some salt sensitive plants such as the
tulip. Epstein and Parr (55) also reported that the excess soluble salts in
potting mixtures using sewage sludge compost may be a problem. However, they
suggested that leaching the mixture with water could alleviate that problem.
This was also reported by Hinesly (52).
The chrysanthemums studied by Kirkham (54) responded most favorably to a
sludge irrigation rate of 50 ml per pot per week. An irrigation rate of 100
ml/pot/ week produced plant leaves that had necrotic margins. The necrosis
was attributed to sludge ponding and poor aeration in the media, rather than
to any nutrient deficiency. The chrysanthemum plants irrigated weekly with
50 ml of liquid sewage sludge had similar nutrient compositions except for N
and K when compared with those plants that were treated with standard amounts
of liquid or pelletized inorganic fertilizers. Nitrogen was higher and K
lower in the sludge treated plants. However, the lower K concentration did
not reduce yields or cause any deficiency symptoms.
43
-------
The turf grass industry has the greatest potential for the utilization of
sewage sludge. In the State of Maryland, this industry is a rapidly expanding
segment of Maryland's agricultural economy (56). In recent years, growth in
the turf grass industry has exceeded overall agricultural expansion. As of
1974, 34,000 ha (85,000 acres) were under cultivation for the production of
sod. The sod industry is estimated today to be a $2 million industry. The
cultivation of this crop using sewage sludge is ideal since the crop is
removed and transported to another area which reduces the accumulation of
residues at the growing site.
Sod needs a deep sandy loam soil with some clay and silt to hold
nutrients. Sod is sometimes grown on organic soils (mulches and peats) which
are excellent from the standpoint of growth and ease of cutting operations.
However, it has been reported that sod grown on organic soils has a tendency
to be coarser and more open, and does not hang together as well as sod
produced on sandy loam soils (57). But research conducted by Darrah et al.
(58) indicated that the best turf growth resulted from seed bed preparation
with composted sewage sludge and maintenance fertilization with liquid di-
gested sludge. They found that the sod with the highest shear strength
resulted from the high sludge treatment after seeding. Based on interviews
with sod farmers, it appears that not enough sewage sludge is available. It
is their opinion that the crops respond favorably to fertilization using the
sludge, and that they will use it as long as they can obtain it. Grasses in
general require large amounts of N (59) for cultivation, and, thus, would be
an ideal non-food crop for sewage sludge applications. The grasses can be
grown for sod, for seed or for energy (for the production of alcohol). In
terms of quantities of sewage sludge, most lawns will require about 8 Kg (17
Ibs^f processed,sewage sludge, or 23 Kg (50 Ibs) of liquid sewage sludge per
93 M (1,000 ft ) once or twice a year.
Generally shrubs and trees are fertilized between December and April.
Fertilizer is only applied once per year. Flowering shrubs and ornamental
trees greater than 7.62 cm (3 in) in diameter require 45 Kg of N/ha (40 Ibs of
N/acre), 90 Kg of P/ha (80 Ibs of P/acre), and 45 Kg of K/ha (40 Ibs of
K/acre); foliage shrubs require 90 Kg of N/ha (80 Ibs of N/acre), 56 Kg of
P/ha (50 Ibs of P/acre), and 34 Kg of K/ha (30 Ibs of K/acre); and ornamental
trees with a diameter less than 7.62 cm (3in) require only 1/4 the NPK
requirements as trees with diameters greater than 7.62 cm (3 in) (59).
Interviews with large nursery owners in the D.C. area revealed some in-
teresting points. For the most part, the usual practice is to fertilize once
at the time of planting and no more. Any increase in the rate of fertiliza-
tion would stimulate new, uneven growth of the trees and shrubs. This growth
must be cut back to shape the trees and shrubs; otherwise they would become
spindly or the shape distorted and thus the tree or shrub would be un-
desirable. Between crops, a cover of rye seed is planted, allowed to grow to
one inch and then plowed under to incorporate organic matter back into the
soil. Therefore, it appears that composted sludge would be beneficial to this
industry and Gouin has shown that composted sludge makes a good potting mix
(47). The compost could also be used as a mulch to provide the organic matter
and to hold water.
44
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Thus, the horticultural industry could benefit by using sewage sludge,
but rates of application and the form in which the sludge would be most
suitable would have to be determined on a case-by-case basis.
Cotton and Soybeans
Cotton and soybeans were included in this study because these crops have
many-potential inedible uses as listed in Table 19. The oil extraction
process used for purifying.the oils rejects all the impurities, and the meals
can be used for the production of inedible products.
It has been reported that cotton will not grow well when irrigated with
sewage effluents that have high boron concentrations (60). Boron is phy-
totoxic to cotton. This element has the tendency to remain in the wastewater
and to move with the soil-water system (61). It is doubtful that sewage
sludges would be toxic to cotton since boron is not concentrated in the
sludges.
Because of the high N demand, the best crop yields are obtained when
cotton is fertilized. In those areas where the crop is not fertilized, crop
rotation is practiced to prevent soil nutrient exhaustion. The average annual
fertilizer requirements of cotton are 82 Kg/ha (73 Ibs/acre) of N, 60 Kg/ha
(53 Ibs/acre) of P as P205 and 70 Kg/ha (62 Ibs/acre) of K as K20 (51).
Soybeans are not normally fertilized since the plant has the ability to
fix N. However, studies by Hinesly (52) show that soybean crop yields can be
increased by fertilization with sewage sludge. In that study, the soybeans
grown on plots with 25.0 mm of sludge had elevated metal concentrations in the
tissues, and did succumb to phosphorus toxicity. However plants grown on the
plots with sludge applications of 6.4 mm and 12.7 mm showed elevated metal
concentrations, but no phytotoxicity was observed.
Over 28 x 10 ha are devoted to raising cotton and soybeans in the U.S.
(51). The leading states in cotton and soybean production, as shown in
Figures 1 and 2, contribute more than 80% of the sludge generated in the U.S.
annually. Based on the pounds of N, P, and K applied to cotton and soybeans in
1973 as shown in Table 20, the substitution of sewage sludge (based on N) for
commercial fertilizers would require an annual utilization of more than 40% of
the sludge generated. The actual percentage of sewage sludge that could be
used would of course be considerably lower, but the potential is there.
Presently, the edible usages for cotton and soybeans far outweigh the
inedible usages. However, one scenario for these crops could be the selection
of one or two states in which these crops would be grown strictly for their
inedible usages. The residues remaining after harvesting and processing
would be used for energy biomass. This scenario if implemented could involve
the utilization of about 15% to 20% of the sludge generated annually in the
U.S.
45
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TABLE 19. NON-FOOD-CHAIN-CROP USES FOR COTTON AND SOYBEANS
COTTON
A. Fiber
Textiles
B. Linters
1. mattresses
2. coarse yarns
3. paper
4. packing material
SOYBEANS
A. Oil
1. High grade industrial enamels
2. Varnish
3. Alkyd resin paints
4. Inks and stains
5. Sealing and caulking compounds
6. Synthetic rubber
7. Drying oils
8. Polishes and waxes
9. Synthetic organic detergents
10. Toilet preparation including shampoos
11. Cosmetics
12. Soap
continued
-------
TABLE 19. (continued)
13. Lubricants
14. Resins and plastics
15. Fatty acids (surfactants, esters and scents)
B. Meal (Protein)
1. Adhesives
2. Paper coatings
3. Water-thinned paints
4. Plastics
- 5. Textile fibers
6. Fire foam stabilizers
7. Printing inks
8. Fillers
9. Core binders
10. Linoleum
11. Emulsifying agents
12. Paper and textile sizing
13. Leather finishes
14. Fertilizer
15. (Active industrial research for new uses)
47
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"M ' .u- i
f V^ ; ;
tmtorL i
^:--^f~~yf ~>.^ /
FIGURE 1. States with significant cotton production
(shaded area)
48
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FIGURE 2. States with significant soybean production
Cshaded area)
49
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TABLE 20. KILOGRAMS OF N, P, AND K APPLIED TO COTTON AND SOYBEANS (51)
N (P205) K?0
Item (Kg/ha/yr) (Kg/ha/yr) (Kq/ha/.yr)
Soybeans 16 47 62
Cotton 82 60 : 70
Hemp, Jute and Sisal
Hemp, jute and sisal are not major U.S. crops. The products from these
crops are presently being imported. They are amenable to cultivation using
sewage sludge. The U.S. grew hemp during World War II when its supplies from
Japan were cut off, but presently it does not appear that there are any
economic advantages for the U.S. production of. these crops.
The jojoba, guayule and euphorbia are plants that have potential eco-
nomic value. Suitable strains of these crops could possibly be cultivated
using sewage sludge as the source of nutrients. However, much research is
needed on the growth requirements of these crops. It is recommended that
fertilization of these crops using sewage sludge be investigated. This would
be an excellent use for the sludge since a valuable resource would be used to
produce valuable products that could reduce the nation's dependancy on im-
ported products. The jojoba is presently being studied extensively at the
University of California, Riverside Campus.
The jojoba is a hardy scrub bush which produces a seed from which oil can
be extracted. The plant grows best in arid climates. The oil is very
similar to whale oil, and could be used as a substitute. The guayule bush
grows in the deserts of the United States. The bush produces a latex which
has the potential of being as versatile as the latex produced by the rubber
tree. The euphorbia plant grows naturally in the semi-arid areas of
California. The leaves produce a latex which, when mixed with acetone,
yields an oil that behaves as crude petroleum.
MOST PROMISING NON-FOOD-CHAIN CROPS
For this study the most promising NFCC were selected from the initial
list of 20 crops using the stated criteria. Based on the above discussion of
each crop category and by application of the criteria, six crops (or crop
categories) emerged as best meeting the goals of this study. These crops and
categories are given in Table 21.
50
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TABLE 21. MOST PROMISING NON-FOOD-CHAIN CROPS SUITABLE FOR
CULTIVATION USING SEWAGE SLUDGE ~_"
Category Crop
Timber Tracts Monoculture timber tracts
operations using softwoods
Forest Nurseries Hardwood and softwood seedlings
Horticulture Specialties Sod
Research Crops Energy biomass trees
Oil Crops Cotton
Soybeans
Discussion of Selection Process
Timber Tracts--
The feasibility of using sewage sludge as a source of nutrients for the
cultivation of hardwood forests, while possible and currently being studied
by other researchers, was not judged to be acceptable by this study because:
1. The optimum growth for hardwoods is best achieved in the open forest
environment and the impacts of sewage sludge on the forest eco-
system have not been fully determined.
2. The N and P requirements for hardwoods are low when compared with
other crops and thus this use of sewage sludge would constitute a
disposal technique rather than a nutrient recovery technique.
3. Hardwoods have a very slow rotation period and the sites tend to be
remote and intermittently accessible.
4. Hardwood forests in general are not in close proximity to sludge
generation centers.
On the other hand, softwoods are amenable to cultivation in monocultures
and the impacts of sewage sludge on those environments would be negligible.
Monoculture operations are accessible and the sites are not that far from
sludge generation centers. While the nutrient requirements for softwoods
are low when compared with other crops, the faster rotation periods for some
species could justify the consideration of sewage sludge as a source of
nutrients. However, the period of application would at best be once every
ten years.
Some of the softwoods do appear to be amenable to cultivation using
sewage sludge and thus this crop was retained as a crop meriting further
study.
51
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Forest Nurseries
The operation of forest nurseries for the production of forest tree seed-
lings met all of the criteria considered in this feasibility study. Thus,
this crop category was retained for further study.
Flax and Flaxseed Farms--
Even though this crop category scored favorably during the analysis
phase of this study, it was decided to delete it from further consideration
because the market for this crop is declining and the possibility does exist
that some of the land used to raise this crop would be used to grow a food
crop.
Horticulture Specialties--
This crop category met essentially all of the criteria considered, and
many nurseries and gardeners cultivating crops that are in this category are
currently using sewage sludge as a soil conditioner and as a source of
nutrients. Thus, this category was retained for further study.
Research Crops
A lot of interest was generated in trying to determine if any of the
research crops selected were suitable for cultivation using sewage sludge.
The jojoba, guayule, and euphorbia grow in arid climates presently. While it
was felt that suitable strains could be developed, there was just not enough
available data to determine feasibility. Thus, it is recommended that those
researchers working with these crops investigate the potential of using
sewage sludge as a source of nutrients for the cultivation of the crops.
The feasibility analysis did show that energy biomass crops could
benefit from the use of sewage sludge as a source of nutrients and thus they
were retained for further study.
Oil Crops--
Cotton and soybeans are food-chain crops and thus clearly do not fit
objectives of this study. However, they were included under the category of
oil crops because the oil purification process could be adjusted to exclude
any metals that might be present. This is true for any crop that is purified
such as sugar cane and sugar beets. However, it was felt that these crops
should be studied because they met every criterion, except the definition.
While there are many oil crops that could utilize the N and P in sewage
sludge, it was felt that the inedible uses of cotton and soybeans were just
too "great to be overlooked. These crops are cultivated in areas very close
to major sludge generation centers and the rotation periods are fast enough
to allow major quantities of sludge to be used. Thus, these crops were
retained for further study.
52
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SECTION 7
CASE STUDIES
METHODOLOGY
Three NFCC crops were selected for in-depth case studies. The crops were
selected based on discussions with EPA and the project data collected. Each
case study examines the feasibility (in terms of land requirements and costs) of
supplying the necessary N and P to the crop through the application of sewage
sludge in lieu of commercial fertilizers. The sludge would serve to replace or
reduce the application of fertilizer and soil nutrients. Data on increased crop
yields are not definitive and are therefore not included in the study.
The feasibility analysis has shown that there are many NFCC that could be
produced using sludge as a source of N, P, and organic matter. Basically, any
crop requiring N and P could be cultivated using sewage sludge provided that
there are no materials in the sludge that would be phytotoxic to the crop. In
addition, the sludge can also serve as a soil conditioner. For certain crops, K
and other minerals might have to be added as supplements if they are absent in
the soil. Also, depending on the soil conditions and the crop, lime might be
needed to maintain proper soil pH levels and to insure immobilization of some of
the metals that might tend to become bioavaiTable to the plant.
Sewage sludge does not contain materials that could be potentially toxic to
any of the crops reviewed here based on documented data. Phosphorus phyto-
toxicity to some of the crops has been documented, but this situation was easily
corrected by leaching the soil with water.
Because it appears that sewage sludge could provide the necessary N and P
for many NFCC, it is necessary that other factors be taken into consideration
.before crops are selected for cultivation. The intent is to derive beneficial
uses of the sludge and to produce crops that are of benefit and use in the market
place. Much of the research and many of the pilot studies on beneficial uses of
sewage sludge have produced products that have little or no market potential.
Consequently, the sludge product has been given away and/or stockpiled and the
crop produced has been given away or plowed under. Unless markets are available
or have been identified, all efforts in this area become exercises in futility.
The crops selected for the case studies are currently being sold on the
open market, with the exception of the research crops. Because these crops are
being actively marketed and in the case of biomass crops, actively researched,
the following information is available:
1. the preferential climatic condition for the crop;
53
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2. the nutrient requirements of the crop (this information is necessary,
since beneficial sludge uses are being analyzed and not sludge dis-
posal alternatives). This information is used for the determination
of the potential amount of sewage sludge that should be used to supply
necessary N and/or P requirements;
3. the economic crop size (i.e., the amount of land presently under
cultivation), the land area required, and the minimum size of a city
that could generate enough sludge to support crop production.
If the cost of supplying nutrients to a crop can be reduced by using sewage
sludge rather than commercial products, then this beneficial use of the sludge
should gain in popularity. Thus, a simple cost/benefit analysis was performed
to determine the costs involved for using sewage sludge in this manner. Those
costs were then compared to the costs involved for the use of commercial pro-
ducts to supply the crop nutrients. Benefit, as used in the cost/benefit
analysis, is the difference between the wholesale purchase price of the commer-
cial source of nutrients and the wholesale purchase price of the alternative
source of nutrients, in this case, sewage sludge (the purchase price is assumed
as no cost to the farmer in this study, unless otherwise noted). Cost, as used
in the cost/benefit analysis, is defined as the aforementioned wholesale prices
and does include labor and equipment required for land application, but it does
not include the costs for environmental monitoring and the cost of land.
Crops Selected for The Case Studies
The following crops were selected for case studies:
1. Cotton
2. Sod
3. Energy Biomass Trees
These crops were selected because sufficient documented information was
available for those crops to quantify the sludge requirements and to estimate
the costs incurred for supplying nutrients. Other factors such as: (1) uses for
the crops; (2) markets available for utilization of the crops; and (3) crop
growth habits and constraints have been discussed in other sections of this
report. Figures 1, 3 and 4 show the geographical locations of growth for each
of the crops selected for the case studies.
Acceptability
There appear to be no significant barriers to sludge utilization for the
production of the selected crops in the context presented. These crops would be
excluded from man's food chain and thus, it is likely that there would be no
adverse reaction from the general public.
The full scale use of sludge for the production of these crops would
involve considerable changes to current fertilizer application practice.
54
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FIGURE 3. States with significant sod production Cshaded area)
55
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..'
FIGURE 4. Millions of acres and percentage of land potentially
available for energy biomass tree production by
region (assuming the utilization of 10% of the non-
agricultural land in each region)
56
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Sludge application equipment tends to differ from that used for chemical fertil-
izers; odors may develop or be present whenever sludge applications occur and
for a time thereafter; and on-site storage of the sludge may be required.
The advantages of sludge application to NFCC are:
Solution to the "where to put it" question
Recovery of P fertilizer value
Recovery of N fertilizer value
Recovery of soil conditioner value
Elimination of ultimate disposal problem
Elimination of incineration option
Reduction of fertilizer use at comparable application costs (depend-
ing on option selected)
The disadvantages may be stated as listed below:
Probable higher costs than commercial fertilizer for application
options other than truck spreading
Transport requirements and costs from POTW to site may be excessive
Need different application schemes and equipment
t Potential "acceptability" problems by applicators.
The major advantage to using sewage sludge for the production of NFCC is
probably related to the fact that sites for the land disposal of sewage sludges
are difficult, if not impossible, to find near urban areas. This difficulty in
finding suitable sites near urban areas occurs because the sludges are not
recognized as a commodity of value by the general public. Thus, no community
wants the disposal site located in its domain. However, using the sludges to
produce crops may tend to elevate the sludges to a commodity of value; the
disposal sites could become beneficial land management options and would be
welcomed by communities as ways of preserving the country side/open spaces and
reducing the potential for development. The use of sewage sludge for NFCC
production may be found to be more acceptable to the general public and the crop
production sites may be more easily obtained.
The major disadvantage to the production of NFCC using sewage sludge may be
the sludge transport costs.
Determination of Land Requirements and Costs
Based on the annual N and P requirements for cotton, sod and biomass and
the N and P content of sewage sludge, the annual sludge application rates
necessary to satisfy the nutrient requirements of each crop were calculated.
Given the quantity of sludge generated annually in each state or region of
the United States and the sludge application rates determined above, the
amount of land in each region that can be fertilized using all of the sludge
produced annually in that region was then calculated. The costs of applying
this sludge to the land by three modes of application were then determined
and compared to the costs of applying commercial fertilizer at rates needed
to satisfy crop nutrient requirements.
57
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Calculations used for determining sludge and fertilizer application rates
and costs of using commercial fertilizer are presented below, followed by a
description of the methods that were used for calculating costs of sludge
application.
Application of Nitrogen to Crops
Sewage sludgeThe N content of most sewage sludges ranges from 2 to
3.3%(51) and 2.5% was assumed for this study. The total N in the
sludge occurs in various forms, and about 30% to 40% of that is the available
N. The sludge application rates were determined as given below:
1. N requirement for cotton: 45 to 135 kg/ha/yr (40 to 120 Ib/acre/yr).
An N value of 79 kg/ha/yr (70 Ib/acre/yr) was assumed
Sludge application rate = 79 kg/ha/vr x 1 MT Sludge
(0.35}(0.025 kg N/kg Sludge) 1000 kg Sludge
9 DMT/ha/yr .(4 DT/acre/yr)
2. N requirement for sod: 191 kg/ha/yr (170 Ib/acre/yr)
Sludge application rate = !!Uig/ha/vr yl HT Sludge
(0.35)(0.025~ kg N/kg Sludge) 1000 kg Sludge
22 DMT/ha/yr (10 DT/acre/yr)
3. N requirement for biomass crops: 112 kg/ha/yr (100 Ib/acre/yr)
Sludge application rate « 112 kg/ha/.yr X1 m Sludge
(0.35)(0.025 kg N/kg sludge) 1000 kg Sludge
13 DMT/ha/yr (6 DT/acre/yr)
Commercial fertilizerAqueous ammonia, containing 30% NFL, was used
as the basic source of commercial N. The fertilizer application rates were
determined as given below (all calculations are on a dry weight basis):
1. N requirement for cotton = 79 kg/ha/yr (70 Ib/acre/yr)
N in 30% aqueous ammonia = 0.30 kg NH.> (14/17) x 1000 kg Fertilizer
1 kg Fertilizer i MT fertilizer
= 247 kg N/l MT Fertilizer
Fertilizer application
rate = 79 kq/ha/vr
247 kg N/MT
0.32 MT/ha/yr (0.14 DT/acre/yr)
58
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Cost of aqueous ammonia fertilizer:
range
use cost of
Cost of spreading the
fertilizer
Cost of custom
application
N requirement for sod
N in 30% aqueous
ammon i a
Fertilizer application
rate
Cost of aqueous ammonia
fertilizer
Cost of spreading
the fertilizer
Cost of custom
application
N requirement for
biomass crops
N in 30% aqueous
ammon i a
Fertilizer application
rate
Cost of aqueous ammonia
fertilizer
Cost of spreading the
fertilizer
Cost of custom
application
$188 to $198/MT ($170 to $180/ton)
$198/MT ($180/ton)
$7.41/ha ($3.00/acre)
$198/MT X 0.32 MT/ha/yr + $7.41/ha
$71/ha ($29/acre)
191 kg/ha/yr
247 kg N/MT Fertilizer
191 kg/ha/yr
247 kg N/MT
0.77 MT/ha/yr (0.35 DT/acre/yr)
$198/MT ($180/ton)
$7.41/ha ($3.00/acre)
$198/MT X 0.77 MT/ha/yr + $7.41/ha
$160/ha ($65/acre)
112 kg/ha/yr (100 Ib/acre/yr)
300 kg N/MT Fertilizer
112 kg/ha/yr__
247 kg N/MT
0.45 MT/ha/yr (0.20 DT/acre/yr)
$198/MT ($!80/ton)
$7.41/ha ($3.00/acre)
$198/MT X 0.45 MT/ha/yr + $7.41/ha
$97/ha ($39/acre)
59
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Application of Phosphorus to Crops--
Sewage sludgeThe P content of most sewage sludge is about the same
as that for N, and 2.5% was used for this study. The total P in the sludge
occurs in various forms, and about 4.6% of that is availablefor crop utilization.
The sludge application rates for p wc:re determined as given below:
1. P requirement for cotton: 59 kg/ha/yr (53 Ib/acre/yr)
Sludge application rate f 59 kq/ha/yr y 1 MT Sludge
(0.46)TO25 kg P/kg Sludge) A 1000 kg Sludge
5.17 DMT/ha/yr (2.3 DT/acre/yrj
2. P requirement for sod: 52 kg/ha/yr (46 Ib/acre/yr)
Sludge application rate 52 kg/ha/yr v 1 MT Sludge
(0.46)(0.025 kg/ P/kg Sludge) 1000 kg Sludge
4.48 DMT/ha/yr (2 DT/acre/yr)
3. P requirement for biomass crops: 92 kg/ha/yr (82 Ib/acre/yr)
Sludge application rate = 92 kg/ha/yr » 1 MT Sludge
(0.46)(0.025) kg P/kg Sludge IQOO kg Sludge
8 DMT/ha/yr (3.57 DT/acre/yr)
Commercial fertilizerPhosphorus pentoxide containing 40% P was used
as the basic source of P for application to crops. These fertilizer application
rates were determined as given below:
1. P requirement for cotton = 59 kg/ha/yr (53 Ib/acre/yr)
P available in fertilizer = 0.40 kg P x 1QQQ kg Fertilizer
I kg Fertilizer * i MT Fertilizer
400 kg P/MT Fertilizer
Fertilizer application
rate = 59 kg/ha/yr
400 kg P/MT
0.15 MT/ha/yr (0.07 DT/acre/yr)
Cost of P205:
Range = $1,345 to $1,455/MT ($1,220 to $l,320/ton)
Use cost of $1,455/MT
Cost of spreading the
fertilizer = $7.41/ha ($3.00/acre)
Cost of custom
application = $1,455/MT X 0.15 MT/ha/yr + $7.41/ha
$226/ha ($91/acre)
60
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2. P requirement for sod
P available in
fertilizer
Fertilizer application
rate
Cost of P205
Cost of spreading the
fertilizer
Cost of custom
application
3. P requirement for
biomass crops
P available in
fertilizer
Fertilizer application
rate
Cost of P205
Cost of spreading the
fertilizer
Cost of custom
application
52 Kj/ha/yr (46 Ib/acre/yr)
400 kg P/.MT Fertilizer
52 kg/ha/yr
400 k~ P/MT
0.13 MT/ha/yr (0.06 DT/acre/yr)
31,455/MT
$7.41/ha ($3.00/acre)
$1,455/MT X 0.13 MT/ha/yr + $7.41/ha
$197/ha ($80/acre)
92 kg/ha/yr (82 Ib/acre/yr)
400 kg P/MT Fertilizer
92 kg/ha/yr
400 kg P/MT"
0.23 MT/ha/yr (0.10 DT/acre/yr)
S1.455/MT
$7.41/ha ($3.00/acre)
S1.455/MT X 0.23 MT/ha/yr + $7.41/ha
$342/ha ($133/acre)
Cost Estimates for Sludge Application--
Cost data used for this study were derived from existing sources in the
literature.
Several conversations were held with project personnel related to how
original cost estimates were constructed. The accuracy of cost estimates for
sludge application is. probably in the range of 50%. The estimates are probably
high rather than low. This is the case because:
Available cost data probably included a number of factors such as
management, legal, site preparation, engineering, etc., which would
be lower or non-existent for small systems.
61
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3EG1N
-^ST
OFTEXT
Available data probably included some transport or sludge" product ipjv
costs (costs incurred at the POTW).
Figures 5; 6, and 7 show the data that were used for calculating unit;
sludge application costs. These [figures show capital costs that have been:
updated to late 1979 costs using 'the ENR CCI of 3131, and operation and main-'
tenance costs that have been updated using the October 1979 Consumer Price Index-*
226-;e-aptta-1-coststn~these-figuresHnclude-land-costSTTo-arr4ve-at--the
capital cost values in Tables 22 through 27, land costs, assumed at $3,706/ha
($l,500/acre),' were deducted from capital costs indicated on Figures 5,
6 and 7; this difference was then amortized at 7 1/8% for 5 years. Operation and^
maintenance costs were read directly from the figures. Total annual costs
represent the sum of the capital costs and the O&M costs.
CASE STUDY 1: ; COTTON PRODUCTION :
Land Requirements j 1
! ! I
The average annual nutrient requirements for cotton are 79 kg/ha (70i
lbsAaereJ-of N> 59 Icg/ha (53-;bs/acre)-of-P-as-P205 and-ZO k-g/ha C62-1 bs/acre)-pfc
K as K-0 (51)i. Liquid sludge application to cotton croplands, in order to:
satisfy the N', and P requirements of .the crop, requires that the sludge be;
applied at an average rate of 9 DMT/ha/yr (4 DT/acre/yr) for N and 5.17'
DMT/ha/yr (2.3 DT/acre/yr) for P. The hectares of land needed in each of the;
cotton producing states to utilize the sludge generated in those states was;
determined by'dividing the quantity of sludge generated in the state by the'
average annual loading rate. In most;cases, as shown on Tables 22 and 23, the
amount of land required to utilize all of the sludge produced in each state?
("Land fertilized") is less than the land that is currently being harvested for:
cotton in that; state ("Land harvested"). In Florida, Kentucky and Nevada, the:
land needed to utilize all of the sludge in each of those states exceds the land:
currently being harvested for cotton. In these three states, then, only ai
fraction of the sludge generated could be used for producing cotton. For
example, in Florida,
sludge generated = 160,801 DMT/yr (177,250 DT/yr)
land under cultivation for cotton
amount of land area needed if all the
production = 2,873 ha (7,099 acres) !
sludge generated in that state was used I
= 160,801 DMT/yr
9 DMT/ha/yr
i
= 17,867 ha (44,149 acres)
I"'
quantity of sludge that could be used in Florida for cotton production, based on;
N, = 2,873 haix 9 DMT/ha/yr
= 25,857 DMT/yr
BOTTOM OF
:MAGE AREA;
OUTSIDE
DiMEiNSiON
FOR TA3LES
B>A-287 (Gin.)
(4-76)
PAGE NUM3EH
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OROPPED
HEAD;
100 i- -.-.
1000
3EGIN
LAST- LINE
OF TEXT »
CAPACITY - DRY TONS SOLIDS PER DAY
ENGINEERING NEWS RECORD:
CCI - CONSTRUCTION COST INDEX = 3131, OCTOBER 1979 (1913=100)
U.S.. DEPT. OF COMMERCE: 1
CPI K CONSUMER PRICE INDEX i* 226, OCTOBER 1979
DRY TONS. (SHORT) x 0.9072 = DRY TONS (METRIC)
Figure-5. Costs of land application of sludge by injection
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-------
TABLE 22. COST OF APPLYING LIQUID SLUDGE TO PROVIDE NITROGEN FOR COTTON CULTIVATION
Sludge Land Sludge
generated harvested required
1977
State (OMT/Yr)
Ala.
Ariz.
Ark.
Calif.
Fla.*
Ga.
Ky.*
La.
Miss.
Mo.
Nev.*
N.M.
N.C.
Okla.
S.C.
Tenn.
Tex.
Va.
90.500
34,800
20.800
428,503
160,801
(25.761)
137,201
53,293
(4.717)
40,000
54.201
72,000
18.300
(3,992)
21.000
107.701
47.100
79,801
126.801
301,502
94,701
(ha) (DMT/Yr)
169,976 90,500
137,600 34,800
384,470 20,800
453,270 428,503
2,873 25,761
97,129 137,201
526 4,717
226,635 40,000
594,917 54,201
105.224 72.000
445 3,992
25,901 21,000
28,734 107,701
135,576 47,100
64,348 79,801
149,741 126.801
182,117 301,502
242,003 94.701
Sludge application rate: 8.97 OMT/ha/yr(4.
Fertilizer
Number in
application
bracket is
rate: 0.32 MT/ha/yr
sludge quantity that
Land
fprtili7pd
Injection
Cap.
O&M
(ha) (S/OHT) ($/OMT)
10,093
3,881
2.3?0
47,789
2.873
15.301
526
4,461
6.045
8,030
445
2,342
12.011
5.253
8,900
14,141
33,625
10,561
0 OT/acre/yr)
(0.14 OT/acre/yr)
can be used.
94
111
118
82
118
87
134
108
103
97
139
118
93
105
96
?3
86
94
31
32
32
29
32
31
44
32
32
31
46
32
31
32
31
31
31
31
Total
Surface irrigation
Cap.
O&M
J/DMT t/ha (S/DMT) ($/DMT)
125 1,121
143 1,283
150 1,345
111 996
150 1,346
118 1,058
178 1,597
140 1 ,256
135 1.211
128 1.148
185 1,659
150 1,345
124 1,112
137 1,229
127 1,139
124 1,112
117 1.049
125 1,121
52
58
65
41
63
47
77
58
57
54
80
65
50
58
53
47
42
52
19
23
26
14
25
18
36
23
21
20
37
26
19
22
20
19
15
19
Truck spread
Total Cap.
J/DMT
71
81
91
55
88
65
113
81
78
74
117
91
69
80
73
66
57
71
O&M
$/na ($/OMT) ($/DMT)
637
727
816
493
789
583
1,014
727
700
664
1,049
816
619
718
655
592
511
637
7
11
14
2
13
6
18
9
9
8
22
13
6
9
7
6
2
6
23
23
24
22
23
23
30
23
23
23
31
24
23
23
23
23
23
23
Total
t/DMT
30
34
38
24
36
29
48
32
32
31
53
37
29
42
30
29
25
29
$/ha
269
305
341
215
323
260
431
287
287
278
475
332
260
287
269
260
224
260
Aqueous
Aflwoni a
30< NH3
($/ha)
71
71
71
71
71
71
71
71
71
71
71
71
71
71
71
71
71
71
CT>
CTl
-------
TABLE 23. COST OF APPLYING LIQUID SLUDGE TO PROVIDE PHOSPHORUS FOR COTTON CULTIVATION
Sludge Land Sludge
generated harvested required
1977
State
Ala.
Ariz.
Ark.
Calif.
Fla.*
Ga.
Ky.*
La.
Miss.
Mo.
Nev.*
N.M.
N.C.
Ok la.
S.C.
Tenn.
Tex.
Va.
(DMT/Yr)
90.500
34,800
20,800
428,503
160,801
(14,813)
137,201
53,293
(2.712)
40,000
54,201
72,000
18,300
(2.295)
21 ,000
107 ,701
47.100
79,801
126,801
301.502
94.701
(ha) (OMT/Yr)
169,976 90,500
T37.600 34,800
384,470 20,800
453,270 428,503
2,873 14,813
97,129 137,201
526 2,712
226,625 40,000
594,917 54,201
105,224 72,000
445 2,295
25,901 21.000
28.734 107,701
135.576 47.100
64,348 79,801
149,741 126,801
182.117 301.502
242,003 94,701
Sludge application rate: 5.17 OMT/ha/yr (2
Fertilizer application rate: 0.15 MT/ha/yr
*Number
in bracket Is
sludge quantity that
Land
fertilized
Injection
Cap.
O&M
(ha) (S/DMT) (S/DMT)
17.553
6.750
4.034
83.110
2,873
26,611
526
7,758
10,512
13,965
445
4,073
20.889
9.135
15,478
24,594
58,441
18,368
.3 DT/acre/yr)
(O.O'/DT/acre/yr)
can be used.
123
163
179
88
189
98
241
156
146
138
275
175
120
153
135
115
93
123
47
48
51
43
51
46
68
48
48
48
69
51
46
48
48
46
44
47
Total
S/DMT
170
211
230
131
240
144
309
204
194
186
344
226
166
201
183
161
137
170
Surface Irrigation
Cap.
O&M
S/ha ($/OMT) ($/DMT)
879
1,091
1,189
677
1.241
744
1,597
1.055
1,003
962
1.778
1,168
858
1,034
946
832
708
879
164
187
191
157
198
164
214
181
178
172
232
191
164
179
171
164
158
164
34
40
43
25
45
32
60
39
37
35
62
43
34
38
35
33
29
34
Truck spread
Total Cap.
O&M
J/DMT {/ha (S/DMT) (S/DMT)
198 1.024
227 1.174
234 1,210
182 941
243 1,256
196 1.013
274 1,417
220 1,137
215 1.111
207 1.070
294 1,520
234 1.210
198 1.024
217 1,122
206 1,065
197 1,018
187 967
198 1,024
19
32
42
7
48
10
68
32
27
21
69
42
15
27
21
13
7
18
25
26
26
25
27
25
39
25
25
25
42
26
25
25
25
25
25
25
Total
$/DMf
44
58
68
32
75
35
107
57
52
46
111
68
40
52
46
38
32
43
S/ha
227
300
352
165
388
181
5535
295
269
238
574
352
207
269
238
196
165
222
P2°5
40X P
(S/ha)
226
226
226
226
226
226
226
226
226
226
226
226
226
226
226
226
226
226
-------
Therefore, 16% of the sludge generated in Florida could be used to supply the N
needed for the total annual cotton production in that state.
For the states of Kentucky and Nevada, 9% and 22%, respectively of the
sewage sludge generated in those'states could be used to supply N to all of the
land under cultivation for cotton production.
For the rest of the cotton producing states, the amount of sludge generated
was not enough to supply the necessary N and P for cotton production. If all of
the sludge generated by each of these states were used to supply N, the amount
of cotton land that could be fertilized in each state ranges from 0.6% to 42%
with the majority of the states generating enough sludge to supply less than 15%
of the cotton lands in each state with sufficient N.
In the case of sludge utilization for the application of P to cotton
cropland, again only Florida, Kentucky and Nevada would fall short in utilizing
all of the sludge generated in their respective states. For the rest of the
cotton producing states, all of the sludge generated by state could be used to
supply P. The amount of cotton land in each state that could be fertilized
using all of the sludge generated by state ranges from 0.5% to 73%. The majority
of the states generate enough sludge to supply less than 20% of the cotton lands
in each state with sufficient P.
Cost/Benefit Analysis
The costs for applying liquid sludge to provide N and P for cotton cultiva-
tion are given in Tables 22 and 23, respectively. Costs were computed for the
injection, surface irrigation and truck spread modes of application. The costs
for custom application of aqueous ammonia and 40% P as PoOc_are a^so given for
cost comparisons. The cost of the sludge is taken as zero Tor this study. The
costs for custom application include the cost of the fertilizer, the cost of
shipping to the central outlet and the cost of application, but not transport to
the site. A more detailed discussion of the types of factors
considered is presented in Section 8.
The figures in Tables 22 and 23 indicate that utilizing sewage sludge to
provide for cotton cultivation can in some cases be economically
competitive with custom application of commercial phosphorus pentoxide fertil-
izer if the sludge is applied via truck spreading. Note that this is true only
for the states fertilizing relatively large quantities of land with sewage
sludge. In this case, the economies of scale associated with larger sludge
projects (excluding land costs) are such that truck spreading of sludge may be
an attractive alternative for supplying P to cotton compared to commercial
fertilizer applications.
All other modes for the application of liquid sludge to supply N or P are 3
to 23 times the costs for custom application for N or P. It should be
remembered, however, that when sludge is applied to provide N or P, the auto-
matic addition of P or N could be an added benefit at no cost to the user. The
additional benefits to be gained are as follows:
68
-------
1. A reduction in the energy consumed for the production of commercial
fertilizers as discussed in Section 4,
2. An improvement in the soil due to the soil conditioner attributes in
the sludge,
3. The reclamation of spent or abused lands unable to produce quality
crops without the addition of soil ammendments and other necessary
soil nutrients, all of which are provided by the sludge, and
4. The beneficial use of a valuable resource-sewage sludge.
CASE STUDY 2: SOD PRODUCTION
Land Requirements
Most lawns require about 8 kg (17 IbsJ of processed sewage sludge, or 23 kg
(50 Ibs) of liquid sewage sludge per 93 M (1,000 ft ) once or twice a year. In
order to satisfy the N and P requirements of sod, liquid sludge must be applied
at an average annual rate of 22 DMT/ha/yr (10 DT/acre/yr) to supply the
necessary N and 4.48 DMT/ha/yr (2 DT/acre/yr) to supply the necessary P.
Again, the quantity of land needed to utilize all of the sludge produced in
each state was calculated by dividing the sludge generated in each state (Tables
24 and 25) by the above sludge application rates for sod. In Florida and
Delaware, this land requirement to use all of the sludge to provide nitrogen for
sod is lower than the land currently harvested for sod; thus all of the sludge
could be used. The quantity of land that could be fertilized (based on nitrogen)
using all of the sludge in each state amounts to 86% and 62% of the land
currently under harvest for sod in Delaware and Florida, respectively.
In all other cases,, the quantity of land needed to utilize all
of the sludge generated was found to exceed the quantity of land being
harvested for sod in each state. The amount of land that can be fertilized
is thus constrained by the amount of land currently harvested rather than by
the quantity of sludge available for application. In Tables 24 and 25, then
(with the two exceptions noted above), "Land fertilized" is equal to "Land
harvested", and "Sludge required" is determined by multiplying the quantity
of land fertilized by the annual sludge application rate. In most cases,
then, the amount of sludge generated in the sod producing states is more than
that which can be utilized for producing the crop. The amount of sludge that
can be used for providing nitrogen for sod ranges from 4% to 100% of the
sludge produced in the respective states. To provide phosphorus, only 1.4%
to 33% of the sludge produced could be used.
Cost/Benefit Analysis
The costs for applying liquid sludge to provide N and P for sod produc-
tion are given in Tables 24 and 25, respectively. The methodology used for
the cotton case study is the same as used here. As with cotton, with the
exception of applying sludge to provide P for sod v.ia truck spreading, the
cost of custom application using commercial fertilizer for supplying N and P
69
-------
TABLE 24. COST OF APPLYING LIQUID SLUDGE TO PROVIDE NITROGEN FOR SOD CULTIVATION
Sludge Land Sludge
generated harvested required
1977
State (DMT/Yr)
Ohio 367,703
' Ind. 160.001
111. 530,704
Mich. 336,702
Wise. 149,901
Minn. 162,001
Iowa 63,701
Miss. 72.001
Nebr. 27.400
Kans. 38,700
Del. 26,900
Ga. 137,201
Fla. 160.801
Tex. 301.502
Ala. 90,500
Conn. 81,900
N.Y. 537,103
N.J. 216,002
Calif. 428,703
Sludge application rate
Fertilizer application
(ha) (
1.416
809
1,619
2.428
1,214
2,104
607
405
486
809
1,416
809
11,736
1,214
526
1,693
971
971
809
DMT/Yr)
31.152
17,798
35,618
53,416
26,708
46.288
13,354
8,910
10,692
17,798
26,900
17.798
160,801
26,708
11,572
37,246
21,362
21,362
17.798
« 22 DMT/ha/yr (9.8
rate * 0.77
MT/ha/yr
Land
fertilized
Cap.
Injection
Surface irrigation
O&M Total
(ha) (S/OMT) (S/OMT) l/UMI
1,416
809
1,619
2.428
1.214
2,104
607
405
486
809
1,223
809
7,309
1,214
526
1,693
971
971
809
DT/acre/yr)
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
15 60
18 63
15 fiO
15 60
16 61
15 60
20 67
21 66
21 66
18 63
16 61
18 63
14 59
17 62
20 65
15 60
17 62
17 62
18 63
Cap.
O&M
$/ha (S/DHT) (S/DMT)
1,320
1,386
1.320
1,320
1,342
1,320
1,474
1,452
1,452
1,386
1,342
1,386
1,298
1,364
1,430
1,320
1,364
1,364
1,386
20
21
19
16
20
17
23
26
26
21
20
21
11
20
25
19
21
21
21
9
11
8
7
10
8
12
14
13
11
10
11
4
10
13
8
10
10
11
Truck spread
Total Cap.
O&M
S/DMT $/ha (S/DHT) (S/DMT)
29
32
27
23
30
25
35
40
39
32
30
32
15
30
38
27
31
31
32
638
704
594
506
660
550
770
880
858
704
660
704
330
660
836
594
682
682
704
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
20
22
20
19
21
19
23
24
23
22
21
22
19
21
23
20
21
21
22
Total
S/DHT
31
33
31
30
32
30
34
35
34
33
32
33
30
32
34
31
32
32
33
S/ha
682
726
682
660
704
660
748
770
748
726
704
726
660
704
748
682
704
704
726
Aqueous
Ammonia
30X NH,
($/ha)
160
160
160
160
160
160
160
160
. 160
160
160
160
160
160
160
160
160
160
160
(0.34 DT/acre/yr)
O
-------
TABLE 25, COST OF APPLYING LIQUID SLUDGE TO PROVIDE PHOSPHORUS FOR SOD CULTIVATION
Sludge Land
generated harvested
State
Ohio
Ind.
Ml.
Mich.
Wise.
Minn.
Iowa
Miss.
Nebr.
Kans.
Del.
Ga.
Fla.
Tex.
Ala.
Conn.
N.Y.
N.J.
Calif.
Sludge
1977
(OMT/Yr)
367.703
160.001
530.704
336.702
149,901
162,001
63,701
72,001
27,400
38,700
26,900
137.201
160.801
301,502
90,500
81.900
537.103
216,002
428.703
application rate
Fertilizer application
(ha)
1.416
809
1,619
2.428
1,214
2,104
607
405
486
809
1,376
809
11,736
1,214
526
1.673
971
971
809
= 4.48
rate » C
Sludge
required
(OMT/Yr)
6,349
3,627
7,258
10,886
5,443
9.426
2,719
1,814
2.177
3,624
6.164
3.624
52.577
5,439
2.356
7,501
4,353
4,353
3,627
DMT/ha/yr (2
.13 MT/ha/yr
Land
fertilized
Injection
Cap.
O&M
(ha) (S/DMT) ($/OMT)
1.416
809
1.619
2.428
1.214
2,104
607
405
486
809
1.376
809
11.736
1.214
526
1.673
971
971
809
.0 OT/acre/yr)
185
214
185
175
191
176
216
218
218
214
185
214
125
191
216
185
204
295
214
56
63
55
53
59
53
68
84
73
63
56
63
47
5?
73
55
61
61
63
Total
Surface irrigation
Cap.
O&M
S/OMT $/ha (S/DMT) ($/DMT)
241 1,080
277 1,241
240 1,075
228 1.021
250 1,120
229 1,026
284 1.272
302 1.353
291 1.304
277 1,241
241 1,080
277 1,241
172 771
250 1,120
289 1,295
240 1,075
265 1.187
356 1,595
277 1,241
177
184
177
165
180
165
186
195
195
184
180
184
153
180
190
177
182
213
184
51
55
50
47
S3
48
60
66
62
55
51
55
37
53
62
50
54
54
55
Truck spread
Total Cap. O&M
S/OMT $/ha ($/DMT) (S/DMT)
228 1,021
239 1.071
227 1.017
212 950
233 1,044
213 954
246 1,102
261 1,169
257 1.151
239 1,071
231 1,035
239 1,071
190 8S1
233 1.044
252 1.129
227 1,017
236 1,057
267 1,196
239 1.071
37 31
48 35
37 31
27 29
45 33
30 29
48 40
50 49
48 42
48 35
37 31
48 35
2 25
45 33
48 42
37 30
45 34
81 34
48 35
Total
S/DMT
68
83
68
56
78
59
88
99
90
83
68
83
27
78
90
67
79
115
83
i/ha
305
372
305
251
349
264
394
444
403
372
305
372
121
349
403
300
353
515
372
P2°5
40X P
(S/ha)
197
197
197
197
197
197
197
197
197
197
197
197
197
197
197
197
197
197
197
(O.OfcDT/acre/yr)
-------
is 2 to 9 times cheaper than the costs incurred if sewage sludges were used
to supply the nutrient. High costs are probably attributable to the small
amounts of land under crop cultivation. Truck spreading of sludge to provide
phosphorus appears to be actually cheaper than fertilizer application only
in Florida, due to the economy of scale associated with applying sludge to
the larger land area that can fertilized in this state. In all other states,
truck spreading of sludge to supply P is more expensive than utilizing
commercial fertilizers although the associated costs are more competitive
than the other application modes for either nutrient. The cost of the sludge
was assumed to be no cost to the user. The additional benefits are the same
as for cotton.
CASE STUDY 3: BIOMASS PRODUCTION
Land Requirements
Table 17 gives the various fertilizer and sewage sludge application
rates that have been used or recommended by many researchers for the produc-
tion of this crop. For this study sewage sludge application rates of 13.45
DMT/ha/yr (6 DT/acre/yr) for N and 7.85 DMT/ha/yr (3.5 DT/acre/yr) for P were
used. -''
The land available for crop production was more than that needed to
utilize all the sludge generated in the biomass producing states. As shown
in Tables 26 and 27, all the sludge generated in those regions or states
could be used to produce these crops. The land area to be fertilized was
determined by dividing the amount of sludge generated in the region or state
by the sludge loading rates. For example, for the northeast region,
annual sludge generation = 1,556,010 MT/yr
applicate rate for N, = 13.450 MT/ha/yr
Therefore, the land area that could be fertilized using sewage sludge, based
on N is,
1,556,010 MT/yr = 115,689 ha
13.450 MT/ha/yr
Thus, if all the sewage sludge generated in the northeast were used to supply
N to the soil for biomass crop production, only 10% of the land that could be
dedicated for this crop would be involved.
The hectares of land that could be fertilized in each region using all of
the sewage sludge generated in those regions for biomass production ranges
from 0.6% to 22%. If biomass production were undertaken in the form of
biomass plantations (monoculture - operations), this would be an excellent
crop for production using sewage sewage.
Cost/Benefit Analysis
The costs for applying liquid sludge to provide N and P for biomass
72
-------
production are given in Tables 26 and 27, respectively. Applying sludge via
surface irrigation and truck spreading is shown in these tables to be cheaper
than applying sludge by injection for both nutrients, although the dif-
ference is more pronounced in the case of N. None of the sludge application
modes to provide nitrogen are competitive with applying commercial fertil-
izer, ranging from 1.25 to 13 times more expensive. For phosphorus, the
values presented in Table 27 indicate that the costs of sludge application
via surface irrigation and truck spreading can in many cases be cheaper than,
or in the range of> costs for applying commercial fertilizer. Again, this is
the case mainly in the regions fertilizing large quantities of land, due to
the associated economies of scale. This is due also to the high costs
associated with using commercial P fertilizer.
SUMMARY :
For the three crops considered, the utilization of sewage sludge to
supply nutrients for the production of cotton and biomass crops does offer a
significant beneficial sludge use option. However, utilization of sludge for
sod production is the most feasible at this time. Sod production would uti-
lize, conservatively, 5% to 10% of the total sludge generated in the sod
producing states. This may represent a significant sludge use option and
should be pursued to the fullest extent possible. Most of the research on
biomass cultivation has not involved the use of sewage sludge to provide N and
P and for soil conditioning. Research on the use of sewage sludge (and even
sewage effluent) as a substitute for commercial fertilizers for the production
of this crop should be encouraged by the sponsoring agency or institution.
Additionally, because of the fast rotation periods being investigated, the use
of sewage sludge would offer additional benefits in terms of its soil con-
ditioner values. While most of the cotton being produced is used in part for
food chain products, the possibility does exist whereby a portion of this crop
could be grown for non-food-chain purposes only. This crop and the soil on
which it is cultivated would respond favorably to sewage sludge applications.
It is evident from the above case studies that all of the sewage sludge
generated cannot be used for the production of NFCC. However, based on just
the three crops presented here, at least 20% of the total sludge generated
could be used for those crops. That is significant. The problem of more
sludge generated than is required for application raises other concerns such as
the need for sludge storage facilities and the need for other beneficial sludge
use options. These "needs" should be addressed if the eventual objective is to
use and to recycle sewage sludge as much as possible.
73
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TABLE 26. COST OF APPLYING LIQUID SLUDGE TO PROVIDE NITROGEN FOR BIOMASS CULTIVATION
Region
North East
(Md.,N.J.,
N.Y.)
Mid-Atlantic
(W.Va., Va.,
N.C.Jenn.,
Ky.)
South East
(S.C.,Ga.,Ala.,
Fla.)
South Gulf
(La..Miss.,
Ark.)
South Central
(Tex..0kla.)
Central
(Iowa.,Mo.,
Ohio)
Great Lakes
(Minn..Wise.,
Mich.)
Mid-West
(N.O..S.D.,
Nebr..
Kans.)
West
(Wash.,0reg.,
Calif.)
Injection
Surface irrigation
Truck spread
Sludge Land Sludge Land
generated harvested required fertilized
1977
Cap. O&M Total Cap. O&M Total Cap. O&M Total
(DMT/Yr) (ha) (DMT/Yr ) (ha> ($/DMT) ($/OMT) J/DMT $/ha ($/OMT) (S/DMT) I/DMT $/ha (S/DMT) (S/DMT) J/DMT t/ha
Aqueous
Ammonia
30X NH3
($/ha)
1.536.010 1,173.646 4.639 115.689 60 22 82 1,103 2
9 121 5 22 27 363
464,103 1,456,940 1,402 34,506 65 23 88 1.184 9 9 18 242 9 23 32 430
468,303 2,063.998 1.414 34.818 64 23 87 1,170 9 9 18 242 9 23 32 430
115,001 1,416,469 347 8,550 74
348.602 1.699.763 1.053 25,919 67
24 98 1.318 18
23 90 1.211 10
11 29 390 11 24 35 471
9 19 255 9 23 32 430
1,194,208 1,133.175 3,606 88.789 60 22 82 1,103 4 8 12 161 6 22 28 377
648,604 1,335,528 1,959 48,224 63
74,701 242,823 226 5,554 74
23 86 1,157 6
24 98 1,318 20
8 14 188 7 23 30 403
12 32 430 13 24 37 498
600,203 202,353 1,813 44,625 64 23 87 1,170 7 9 16 215 7 23 30 403
97
97
97
97
97
97
97
97
Sludge application rate: 13.45 OMT/ha/yr (6 DT/acre/yr)
Fertilizer application rate: 0.45 MT/ha/yr (0.20 DT/acre/yr)
-------
TABLE 27. COST OF APPLYING LIQUID SLUDGE TO PROVIDE PHOSPHORUS FOR BIOMASS CULTIVATION
en
Injection
Surface irrigation
Truck spread
Region
North East
(MC1..N.J..
N.Y.)
Mid-Atlantic
(W.Va., Va..
N.C.Jenn..
Ky.)
South East
(S.C..Ga..Ala..
Fla.)
South Gulf
(La.,Miss..
Ark.)
South Central
(Tex.,0kla.)
Central
(Iowa.,Mo.,
Ill.,Ind.,
Ohio)
Great Lakes
(Minn..Wise.,
Mich.)
Mid-West
(N.O..S.D.,
Nebr.,
Kans.)
West
(Wash.,0reg.,
Calif.)
Sludge Land Sludge Land
generated harvested required fertilized
1977
Cap. O&M Total Cap. 04M Total Cap. OiM Total
(DMT/Yr) (ha) (OMT/Yr) (ha) (S/DMT) (S/DMT) J/DMT $7ha" (J/DMT) ($/DMT) J/DMT J/ha (J/OMT) (J/DMT) {/DMT t/ha'
Sludge application rate: 7.85 OMT/ha/yr (3.5 OT/acre/yr)
Fertilizer application rate: 0.23 MT/ha/yr (0.10 DT/acre/yr)
40* P
($/ha)
1.536,010 1.173,646 1.536,010 198.321 43 31 74 581 30 11 41 322 14 23 37 290 342
464,103 1,456,940 464,103 59,153 64 31 95 746 32 13 45 353 18 24 42 330 342
468,303 2,063,998 468,303 59,688 64 31 95 746 32 13 45 353 18 24 42 330 342
115,001 1,416.469 115.001 14.658 81 32 113 887 34 19 53 416 25 24 49 385 342
348,602 1,699,763 348,602 44.432 64 31 95 746 32 14 46 361 18 24 42 330 342
1,194.208 1.133.175 1.194.208 152.210 49 31 80 628 30 12 42 330 16 23 39 306 342
648.604 1.335.528 648,604 82,669 62 31 93 730 30 12 42 330 17 24 41 322 342
74,701 242,823 74,701 9,521 85 33 118 926 35 20 55 432 26 25 51 400 342
600,203 202,353 600.203 76,500 64 31 95 746 31 13 44 345 17 24 41 322 342
-------
SECTION 8
COST ANALYSIS
BACKGROUND
It is desirable to compare the cost of the use of sludge for its nutrient
and soil conditioner values with the cost of commercial fertilizer. In making
such a comparison, however, a number of important factors which are related to
each (fertilizer and sludge) make comparisons difficult.
A straightforward cost comparison approach would consist of determining
the following:
Fertilizer Sludge
A. Cost of fertilizer A. Cost of sludge
B. Cost of transportation B. Cost of transportation
C. Cost of application C. Cost of application
In the case of fertilizer, the cost of fertilizer purchased at an outlet
by a farmer includes the cost of production, transportation and profit. The
farmer must then transport the fertilizer to the location of interest and
.apply it. Services are available to transport and apply fertilizer for
farmers. For example, the Southern States Cooperative will provide such a
service to the farmer at a cost. For the purposes of analysis during this
study, the current cost of fertilizer was determined from the chemical market-^
ing literature (62), and the costs of transport and application (custom appli-
cation) were determined based on information from companies which provide
that service and from the literature (63).
In the case of sludge, a determination of the cost factors was much more
complex. Since sludge is not in common use for application to crops, even
NFCC, and is not considered to be a "commodity", it was difficult to consider
the cost of the sludge as recoverable. The cost of sludge, therefore, for any
applications to NFCC over the near term future should probably be considered
zero. This means that the cost of sludge production should be totally al-
located to the cost of wastewater handling, treatment and disposal. There is
a significant cost associated with the production of sludge. Total costs may
amount to one-half of the sewage treatment expenditures on a total annual cost
basis at a typical sewage treatment plant.
It is difficult, if not impossible, to determine sludge handling, de-
watering and disposal costs accurately because of the many different account-
ing systems which are currently in use by POTW operating authorities. The
76
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cost to the consumer, however, may be widely different from the cost of actual
production. The price is often kept low in an attempt to get rid of excess
quantities. For example, the December 1979 cost of sludge was $4.52 per MT
($4.10/ton) F.O.B. Chicago (62). At this price, even if the cost of sludge is
included in this analysis, it is a small percentage of the combined sludge
transport and application cost.
Also, costs for various alternatives for sludge handling and disposal
are often presented in the most favorable light depending on which option is
being promoted. Even in the cases where costs have been assembled and analyzed
with reasonable diligence, it is difficult to separate costs of sludge
production from the costs of sludge transport and application to the land.
For the purposes of this study, various sludge disposal experiences in-
volving application to the land in the U.S. were analyzed. Data were avail-
able from Chicago, Los Angeles/Orange County Metropolitan Area (LA/OMA), San
Francisco and elsewhere (64, 65, 66, 67). It appeared that the San Francisco
study had included the results of previous studies and was a summary in
itself. It was, therefore, used as a primary reference for this work.
Based on a review of the cost data, it was difficult to determine what
had been included in capital costs and the operating and maintenance costs.
Trucks for transport, for example, might have been included in the capital
cost or a leasing assumption might have been made. For any sludge application
venture, site preparation costs for storage areas and a cost for the operation
and maintenance of storage facilities should be included. This was uncertain
in some of the reports.
It was also difficult to determine the lifetimes of spreading, storage
and sludge moving equipment at the site because of a general lack of long-term
experience in the U.S. Lifetimes used for annualizing costs for such equip-
ment ranged from 5 to 20 years. Transportation requirements for sludge are
fixed in that the sludge must be moved from generating points at sewage
treatment plants to points of application which may be long distances away.
Fertilizer sales operations, on the other hand, will normally be located
centrally for potential use by the farmers. Also, the costs of fertilizer
"off the shelf" at the outlet already include some transportation costs (pro-
bably by train from the point of manufacture to the point of distribution).
The application of sludge to crops - even NFCC which require longer
growing periods - is likely to be seasonal. Weather conditions will be the
most prominent constraint throughout the northern and Plains states. Changes
may, therefore, be required at the POTW in order to accommodate the-large
scale application of sludge to NFCC. Because of pick-up schedules, storage
facilities may be required. Because of application techniques and equipment,
it may be desirable to produce sludge with varying water composition in order
to facilitate application during different times of the year and/or for dif-
ferent crop types.
There are other considerations which complicate the cost comparison
picture. A farmer buys commercial fertilizer on the basis of NPK content.
Sludge, on the other hand, will provide N, some P and very little K. The cost
77
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of augmenting sludge with additional K was not considered in this study. The
types of equipment used to apply commercial fertilizer versus that required to
apply sludge may be different for terrain, crop type and weather conditions.
In the case of application of sludge to NFCC, it may be possible to
consider the application of sludge to accelerate growth conditions in cases
where no commercial fertilizer is currently being applied.
Because of the foregoing considerations and others, it was not possible,
based on currently existing data and information, to fully draw comparisons
between current commercial fertilizer costs and expected costs for sludge ap-
plication. The determination of accurate costs for sludge application alter-
natives is clearly an area for further research and development effort, and if
ventures are to be successful and alternatives made believable, such further
work should be done in the near future.
A cost comparison has been developed and the information is presented
under various conditions in order to perform a sensitivity analysis and pro-
vide the reader with a general idea of how costs might vary depending on
various conditions. .
DISCUSSION AND SUMMARY
Sludge Application Costs Comparisons
It must be emphasized that applying the sludge based on the N content
will simultaneously supply the soil with more P than the crop needs. For most
crops this will probably not be a problem. However, several crops (soybeans
and possibly the Douglas fir) have shown a decrease in growth due to phos-
phorus phytotoxicity. Thus, the application of the sludge based on P might be
preferable if phosphorus phytotoxicity is suspected of being a concern. The N
requirements for the crop will not be sufficient, if sludge is applied based
on P. The N in the soil might be sufficient, or supplemental N in the form of
commercial fertilizer might have to be added.
Table 28 summarizes the total annual cost (O&M plus annualized capital
cost) for sludge application to the three selected crops. The costs are pre-
sented based on supplying required quantities of N and P in each case; costs
for providing the same quantities of N and P using commercial fertilizer are
given for comparison. These cost figures do not include the cost of trans-
porting sludge to the site nor the cost of storage. Details of costs derived
during the study are presented in Tables 22 through 27. These tables also
give the results by state or region for each of the three crops.
For this feasibility study, the cost values were based on three modes of
application - injection, surface irrigation and truck-spreading of liquid
sludge. It was found that, while some effort has been made to determine the
cost of sludge application, most of the results reported do not show exactly
what items were included in the cost values. The cost curves (Figures 5 to
13) used in this study were based on a study of sludge application in the San
Francisco Bay Region (65).
78
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TABLE 28. COST COMPARISONS FOR SLUDGE AND COMMERCIAL FERTILIZER
Application
Mode
Injection
Surface
Irrigation
Truck
Spreading
Cotton Sod Blomass
Units N(S)1 Fertilizer2 P(S)3 Fertilizer4 N(S)1 Fertilizer2 P(S)3 Fertilizer4 N(S)1 Fertilizer2 P(S)3 Fertilizer4
J/OMT 137
J/ha 1,229
J/DMT 79
J/ha 709
J/DHT 33
J/ha 296
198
71 1
198
71 1
198
71
200 1.455 62 198 2,58 1,455 89 198 95
,034 , 226 1,364 160 1,156 197 1,197 97 746
218 1,455 30 198 234 1,455 19 198 46
,127 226 660 160 1,048 197 255 97 361
56 1,455 32 198 75 1,455 31 198 43
290 226 704 160 336 197 417 97 338
1,455
342
1,455
342
1,455
342
N(S) « Nitrogen supplied using POTM sludge (does not Include cost of sludge).
2 Fertilizer »
Nitrogen supplied using commercial fertilizer (custom application).
3 P(S) Phosphorus supplied using POTW
4 Fertilizer «
Phosphorus supplied using
* The cost data presented for the sludge
at the site.
sludge (does
commercial
not Include cost of sludge).
fertilizer (custom application).
and the commercial fertilizer do not Include the cost of transportation to the site and the cost of storage
10
-------
This study considered various regions and states. The primary impact on
regional cost variations is due to the scale of sludge application. The Con-
struction Cost Index (CCI) was used to adjust costs given in the literature to
September 1979 (national average basis). The maximum regional cost varia-
tions in the CCI were about 7% for all cities (analysis conducted using March
1979 data). Most variations were less than 5%. The regional costs, there-
fore, were not computed using regional CCI values.
Any application of sludge to recover the N value involves the coinci-
dental application of P and K as well. Some cost value could properly be
claimed for the P and K recovery, especially in the case where NPK values as a
whole are desired for the crop. Similarly, when applying sludge for the P
value, there is a synonymous recovery of N and K. However, in both instances,
the coincidental nutrient application is a benefit derived by using sewage
sludge; no cost values are claimed. To illustrate the impact on the cost com-
parison v/hen coincidental nutrient application is accounted for, the data on
Table 29 were prepared. The fertilizer costs presented include a mixture of
the required quantities of N and P for the crops. The value of K has not been
included because of the relatively small sludge K content. Table 29 shows the
following:
1. For all sludge application modes considered, application by injec-
tion is the most expensive with one exception. Application by
surface irrigation is more expensive when applying sludge, based on
P, to cotton.
2. Truck spreading is the cheapest application mode except for apply-
ing sludge, based on N, to sod or biomass. Application of sludge,
based on N, to sod or biomass is cheaper when surface irrigation is
used. Truck spreading appears to be cost competitive with custom
application of the commercial fertilizer mixture.
3. Application of sludge, based on N or P, to biomass using surface
irrigation or truck spreading is cheaper than custom application of
a mixture of commercial N and P.
Transportation Costs
The most significant impact on regional costs variations will clearly be
due to the transportation costs from the centers of sludge generation to the
application sites. Transport costs were considered separately in this study.
Transportation costs are presented in Figures 8 through 13 for 20, 40 and 60
mile distances and for liquid and cake shipping options. In most cases, cost
differences were apparent among pipeline, barge, railroad and truck. Figures
11, 12 and 13 show transport costs for the cake option (pipeline not appli-
cable to the transport of sludge cake). Trucking costs were largely non-
varying for the full range of production values. Trucking operations, how-
ever, are convenient for use at small plants where rail sidings are not
feasible. As expected, there is little economy of scale in the case of
trucking sludge cake. There is little economy of scale for rail transport at
lower sludge quantities and distances. Rail and barge transport become more
cost efficient at longer transport distances. Barge transport is of course
30
-------
**
TABLE 29. COST COMPARISONS FOR SLUDGE VERSUS COMMERCIAL FERTILIZER
(FERTILIZER COSTS INCLUDE BOTH N AND P)
00
Application mode N(S)
Injection
Surfoci?
rriiiition
spread
1.229
709
296
Cotton
Average total annual cost ($/ha)
Sod
P(S)
Fertilizer *
N(S)
F(S)
Fertilizer*
N(S)
1.034
1.127
290
290
290
290
1.364
660
704
1.156
1.048
336
350
350
350
1.197
255
417
* All fertiliser costs are for custom application.
t'r-y weight basis
Biomass
P(S)
746
361
338
Fertilizer
433
432
432
-------
not applicable to inland POTW's or inland application sites.
Cake transport implies a number of considerations which affect total
system costs for NFCC application. If cake is being transported, dewatering
costs at the POTVI are probably higher than for other options. Cake may
require re-slurrying at the application site for certain types of spreading.
Unit costs for rail and truck transport of liquid sludge are similar and
fairly constant for all ranges presented. Pipeline costs are affected by
pumping station requirements, but there is a significant economy of scale for
increased capacities. Pipelines, however, require a fixed commitment over
long periods of time and are very capital intensive. Rail transport is not
labor intensive. Existing rail lines and facilities can be used with little
or no adverse impact, and trains have a very low fuel consumption per metric
ton-kilometer.
Pipelines and barges for liquid sludge transport and barges for sludge
cake transport are clearly more cost efficient for most ranges of potential
application, but are very limited by site, right of way, and on/off loading
requirements.
Over the distances analyzed, the costs for transport of sludge cake
averaged 327/DMT ($25/DT) and for liquid sludge, the costs for transport
averaged $110/DMT ($100/DT) for both rail and truck, which are likely to be
the most common options. The costs for sludge transport and application could
be increased from two to seven orders of magnitude over the costs for applica-
tion alone.
For the three sludge application modes investigated, the costs for
applying the sludge, based on N, range from 41% less than the cost of custom
application of a commercial fertilizer mixture to 324% greater than the cost
of custom application. When transport costs are added to the sludge
application costs, the total cost for the sludge ceases to be cost competitive
with custom application, even for the-cheaper application modes. For example,
in the case of N application, for biomass production using surface irrigation
(Table 29), the cost for sludge application, on a $/ha basis, is 41% less than
the cost for custom application ($/ha) of a mixture of N and P commercial
fertilizers. When the transport cost (S/DMT) for sludge cake is added to the
application cost of the sludge, the cost of the sludge is increased by 142%
(see Table 28). This 142% increase in the sludge cost, on a $/DMT basis,
increases the sludge cost, on a $/ha basis, from 41% less than the cost for
custom jipplication to 43% greater than the cost for custom application of a
fertiliser mixture. This shows that adding transport cost to the application
cost would put most options considered far out of the range of possible
consideration (based on costs alone). The transport costs for commercial
fertilizer are not that significant, because the seller of the product usually
locates near the centers of use.
Clearly, a great many permutations are possible among transport modes,
application types and rates and crop types. A detailed analysis of the many
alternative combinations is beyond the scope of this study. The data and
information, however, are presented to permit a more detailed examination.
82
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The application rates for sludge affect costs. Where sludge quantities are
small, e.g., P injection application to sod in the Mississippi case, (see
Table 25), costs are high when compared to costs for application of commercial
fertilizer and when compared to other states or regions where application
rates are higher. In general, the low sludge application rates result in an
unfair comparison because equipment and other capital costs are annualized
with a poor economy of scale.
Clearly, if sewage sludge is to compete with commercial products for
supplying the necessary N and P for crop production, the costs for operation
will have to be borne by the municipality generating the sludge. If the
municipality would transport the sludge to the site of application and provide
the application equipment, then the sludge would be a sought after product
when costs for this product are compared with the costs for the commercial
product.
83
-------
1000
CAPACITY - DRY TONS SOLIDS PER DAY
ENGINEERING NEWS RECORD:
CCI - CONSTRUCTION COST INDEX = 3131, OCTOBER 1979 (1913=100)
U.S. DEPT. OF COMMERCE:
CPI - CONSUMER PRICE INDEX = 226, OCTOBER 1979
DRY TONS (SHORT) x 0.9072 = DRY TONS (METRIC)
Figure 8. Costs of liquid sludge transport - 20 miles.
84
-------
10301
1000
CAPACITY - DRY TONS SOLIDS PER DAY
ENGINEERING NEWS RECORD:
CCI - CONSTRUCTION COST INDEX = 3131, OCTOBER 1979 (1913=100)
U.S. DEPT. OF COMMERCE:
CPI - CONSUMER PRICE INDEX = 226, OCTOBER 1979
DRY TONS (SHORT) x 0.9072 = DRY TONS (METRIC)
Figure 9. Costs of liquid sludge transport - 40 miles,
85
-------
1000
1000
CAPACITY - DRY TONS SOLIDS PER DAY
ENGINEERING NEWS RECORD:
CCI - CONSTRUCTION COST INDEX = 3131, OCTOBER 1979 (1913=100)
U.S. DEPT. OF COMMERCE:
CPI - CONSUMER PRICE INDEX = 226, OCTOBER 1979
DRY TONS (SHORT) x 0.9072 = DRY TONS (METRIC)
Figure 10. Costs of liquid sludge transport - 60 miles,
86
-------
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CAPACITY - DRY TONS SOLIDS PER DAY
1000
ENGINEERING NEWS RECORD:
CCI - CONSTRUCTION COST INDEX = 3131, OCTOBER 1979 (1913=100)
U.S. DEPT. OF COMMERCE:
CPI - CONSUMER PRICE INDEX = 226, OCTOBER 1979
DRY TONS (SHORT) x 0.9072 = DRY TONS (METRIC)
Figure 13. Costs of sludge cake transport - 60 miles,
89
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;
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TECHNICAL REPORT DATA
(Please read Inunctions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION»NO.
4. TITLE AND SUBTITLE
Production of Non-Food-Chain Crops with Sewage Sludge
5. REPORT DATE
Mav 1980 (issuing date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Lilia A. Abron-Robinson, Cecil Lue-Hing,
Edward J. Martin, David Lake
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
PEER Consultants, Inc. & Environmental Quality Systems
Inc.
1160 Rockville Pike, Suite 202
Rockville. Maryland 20852
36HLC, D.U. yi21,- task C/38
11. CONTRACT/GRANT NO.
68-03-2743
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati. Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Research & Development
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Project Officer: Gerald Stern (513) 684-7654
16. ABSTRACT
Feasibility and market potential were determined for non-food-chain crops cultivated using
sewage sludge. ........
Non-food-chain crops that are currently being sold on the open market or that-have, a good
potential for marketability were selected. From a list of 20 crops, 3 were selected and subjected
to a cost analysis to determine how the costs for cultivation using sewage sludge compared with
the costs for cultivation using commercial fertilizer.
Cotton, sod, and energy biomass trees were determined to have the best potential for cultivation
using sewage sludge, based on the market values and nutrient requirements for each crop, and on
the hectares presently under cultivation for production of these crops.
Results indicate that large quantities of sewage sludge can be used, based solely on the nitrogen
and phosphorus requirements for the cultivation of these crops. In addition, it was determined
that although the total costs for fertilization using commercial fertilizer are less than the costs
for using sewage sludge, the latter would be viewed more favorably if the costs were borne by
the municipality generating the sludge.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sludge, Sludge disposal, Cost comparison,
Cost effectiveness, Cost estimates,
Feasibility, Marketing value
Non-food-chain crops,
Marketing potential,
Sewage sludge, Compari-
son with commercial
fertilizer
13B
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
108
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
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