PB83-190280
Resource Conservation and Utilization in Animal Waste Management-
Volume II. Use of Aerobic Stabilization to Enhance the Value of
Animal Manures as Feedstuffs
John H. Martin, et al
Cornell University
Ithaca, New York
March 1983
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
-------
EPA-600/2-83-024b
March 1983
RESOURCE CONSERVATION AND UTILIZATION IN
ANIMAL WASTE MANAGEMENT - VOLUME II
Use of Aerobic Stabilization to Enhance the
Value of Animal Manures as Feedstuffs
by
John H. Martin, Jr.
Raymond C. Loehr
Thomas E. Pilbeam
Cornell University
Department of Agricultural Engineering
Ithaca, New York 14853
Grant Number R806140010
Project Officer
Lynn R. Shuyler
U.S. Environmental Protection Agency
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 2.
EPA-600/2-83-024b
4. TITLE AND SUBTITLE
Resource Conservation and Utilization in Animal Waste
Management - Volume II
Use of Aerobic Stabilization-to Enhance the Value of
AnimaT Manures on Feedstutfs
7. AUTHOR(S)
John H. Martin, Jr. , Raymond C. Loehr, and Thomas E.
Pi Ih^am
^^am^n^o^^I^^af^n^^lring
Cornell University
Ithaca, NY 14853
1fj .sS°^ftr'8Hra¥n^a'fmt%THfefF Agency
Robert S. Kerr Environmental Research Laboratory
P.O. Box 1198
Ada, OK 74820
3. RECIPIENT'S ACCESSION NO.
?33 ? 19028!)
5. REPORT DATE
March 1983
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO. j
10. PROGRAM ELEMENT NO.
APBC
11. CONTRACT/GRANT NO.
R-806140
13. TYPE OF REPORT AND PERIOD COVERED
Final, Vol. II
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
is. ABSTtfn(5Ts investigation evaluated the potential of aerobic stabilization to increase
the value of animal manures as feedstuffs. Laboratory scale batch and continuous flow
studies using laying hen manure as a substrate were conducted. The batch studies
conducted were for periods of 15 and 10 days. Completely, mixed continuous flow
reactors were operated at retention time of 3, S, 7, and 10 days.
Results from both sets of studies indicated that the essential amino acid content
and thus the potential value of laying hen manure as a feedstuff can be substantially
increased with short-term aeration.
Aerobically stabilized laying hen manure appears to be a well-balanced source of
the essential amino acids required by White Leghorn laying hens. Such stabilized
manure generally is comparable to soybean meal in essential amino acid composition.
If used to replace tap water, aerobically stabilized laying hen manure could furnish
up to 10% of the daily protein requirement (1.7 gm/hen-day) of a White Leghorn laying
hen and result in an estimated reduction in feed costs of $0.017/dozen eggs produced.
This appears to be adequate to justify the cost of aeration for waste stabilization
and odor control.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
Agricultural Wastes
Animal Husbandry
Animal Nutrition
Aerobic Processes
13. DISTRIBUTION STATEMENT
Release Unlimited
b.lDENTIFIERS/OPEN ENDED TERMS
Aerobic Stabilization
Livestock Manure
Poultry Manure
Nutrient Value
Refeeding Value
19. SECURITY-CLASS (This Report)
Unclassified
tfhm^rfSbfl53 (This page)
c. COSATl Field/Group
02/A, C, E
21. NO. OF PAGES
6f
22. PRICE
EPA Form 2220-1 (9-73)
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DISCLAIMER
Although the research described in this article has been funded wholly or
in part by the United States Environmental Protection Agency through contract
or grant R-806140 to Cornell University, it has not been subjected to the
Agency's required peer and policy review and therefore does not necessarily
reflect the views of the Agency, and no official endorsement should be inferred.
Mention of trade names or commercial products does not constitute endorsement
or recommendation for use. '
11
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FOREWORD
EPA is charged by Congress to protect the Nation's land, air and water
systems. Under a mandate of national environmental laws focused on air and
water quality, solid waste management and the control of toxic substances,
pesticides, noise, and radiation, the Agency strives to formulate and imple-
ment actions which lead to a compatible balance between human activities and
the ability of natural systems to support and nurture life. In partial
response to these mandates, the Robert S. Kerr Environmental Research Lab-
oratory, Ada, Oklahoma, is charged with the mission to manage research
programs to investigate the nature, transport, fate, and management of
pollutants in ground water and to develop and demonstrate technologies for
treating wastewaters with soils and other natural systems; for controlling
pollution from irrigated crop and animal production agricultural activities;
for controlling pollution from petroleum refining and petrochemical indus-
tries; and for managing pollution resulting from combinations of industrial/
industrial and industrial/municipal wastewaters.
This phase of the project was initiated to evaluate the potential of
aerobic stabilization to increase the value of animal manure as feedstuffs.
Results indicate that the essential amino acid content of laying hen manure
can be substantially increased by short-term aeration. These results along
with the economic analysis appears to be adequate to justify the use of
aeration of poultry wastes for waste stabilization, odor control and
utilization as a feedstuffs. The information is useful in determining the
optimal practices for waste management systems which will lead to the
development of Best Management Practices for poultry wastes.
Clinton W. Hall, Director
Robert S. Kerr Environmental
Research Laboratory
111
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ABSTRACT
Previous research has demonstrated that aerobic stabilization can be an
effective process for reducing the air (odor) and water pollution potential
of livestock and poultry manures. This investigation evaluated the poten-
tial of aerobic stabilization to increase the value of animal manures as
feedstuffs. Laboratory scale batch and continuous flow studies using laying
hen manure as a substrate were conducted. The batch studies conducted were
for periods of 15 and 10 days. Completely mixed continuous flow reactors
were operated at retention times of 3, 5 7, and 10 days.
Results from both sets of studies indicated that the essential amino
acid content and thus the' potential value of laying hen manure as a feed-
stuff can be substantially increased with short-term aeration. In the
continuous flow studies, a retention time of three days resulted in a 22%
increase in the quantity of essential amino acids present. Longer periods
of aeration (retention times exceeding three days) were found to be detri-
mental to the potential value of laying hen manure as a source of amino
acids.
Aerobically stabilized laying hen manure appears to be a well balanced
source of the essential amino acids required by White Leghorn laying hens.
Such stabilized manure generally is comparable to soybean meal in essential
amino acid composition. If used to replace tap water, aerobically stabil-
ized laying hen manure could furnish up to 10% of the daily protein require-
ment (1.7 gm/hen-day) of a White Leghorn laying hen and result in an esti-
mated reduction in feed costs of $0.017/dozen eggs produced. This appears
to be adequate to justify the cost of aeration for waste stabilization and
odor control.
This report was submitted in partial fulfillment of Grant No.
R806140010 by Cornell University under the sponsorship of the U.S. Environ-
mental Protection Agency. This report covers the time period of 1 October
1978 to 31 December 1980.
-iv-
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CONTENTS
Forward iii
Abstract iv
Figures vi
Tables viii
Abbreviations and Symbols x
Acknowledgements xi
1. Introduction 1
Background I
Project Objectives 9
2. Conclusions and Recommendations 10
3. Methods and Materials 12
Batch Studies .- 14
Continuous Flow Studies 17
Analytical Methods .... 17
4. Results 18
Raw Waste Characteristics 18
Batch Studies 18
Continuous Flow Studies 33
Summary 42
5. Discussion 43
Nutritive Value 43
Utilization 43
System Design 47
Summary 47
References 50
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FIGURES
Number Page
1 Crude protein content as a function of particle size for swine
oxidation ditch mixed liquor 4
2 Schematic of reactors and ancillary equipment used for batch
and continuous flow studies 13
3 Mixed liquor total and volatile solids concentrations, expressed
as fractions of initial concentrations, as a function or
aeration time during batch aerobic stabilization 22
4 Mixed liquor amino acid concentrations, expressed as fractions
of initial concentrations, as a function of aeration time
during batch aerobic stabilization 25
5 Mixed liquor essential amino acid concentrations, expressed as
fractions of initial concentrations, as a function of aeration
time - batch studies 26
6 Mixed liquor gross energy concentrations, Kcal/JZ,, as a function
of aeration time - batch studies 27
7 Gross energy content of mixed liquor volatile solids, cal/gm VS,
as a function of aeration time - batch studies 27
8 Graphical determination of biodegradable and refractory
fractions of laying hen manure volatile solids 28
9 Reduction of the biodegradable fraction of laying hen manure
volatile solids as a function of aeration time during batch
aerobic stabilization 29
10 Oxygen uptake rates as a function of time of aeration - batch
studies 30
11 Mixed liquor chemical oxygen demand as a function of time of
aeration - batch study II 31
12 Mixed liquor concentrations of ammonia and oxidized forms of
nitrogen - batch study I 32
-vi-
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Number
13 Mixed liquor organic nitrogen as a function of aeration time -
batch studies 34
14 Amino acid nitrogen, expressed as a percentage of initial total
nitrogen, as a function of aeration time - batch studies ... 35
15 Amino acid nitrogen, expressed as a percentage of mixed liquor
organic nitrogen, as a function of aeration time - batch
studies 36
16 Relationships between total and essential amino acid concentra-
tions and retention time - continuous flow studies 38
17 Relationships between total and volatile solid concentrations
and retention time - continuous flow studies 38
18 Relationship between mixed liquor chemical oxygen demand concen-
trations and retention time - continuous flow studies 39
19 Relationship between oxygen uptake rates and retention time -
continuous flow studies 39
20 Mixed liquor concentrations of organic, ammonia, nitrite, and
nitrate nitrogen - continuous flow studies 40
21 Relationship between amino aeid nitrogen expressed as a per-
centage of organic nitrogen and retention time - continuous
flow studies 41
22 Process flow diagram for design example 48
-vii-
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TABLES
Number Page
1 Performance of Weanling Rats Fed Oxidation Ditch Residue (ODR)
in Place of Casein, Starch, or Soybean Meal 2
2 Amino Acid Concentration as a Function of Particle Size for
Swine Oxidation Ditch Mixed Liquor 3
3 Composition of Swine Oxidation Ditch Mixed Liquor Used by
Harmon et_ al^. (1973) in Feeding Trials Involving Feeder Pigs. . 5
4 Performance of Feeder Pigs Fed 12% Protein Corn-Soybean Meal
and Corn Diets Combined with Swine Oxidation Ditch Mixed
Liquor and Tap Water 5
5 Performance of Feeder Pigs Fed Swine Oxidation Ditch Mixed
Liquor as a Tap Water Substitute in Combination with a 12%
Protein Corn-Soybean Meal Diet 7
6 Comparison of the Amino Acid Composition of Swine Oxidation Ditch
Mixed Liquor, and Fresh and Dried Swine Feces 7
7 Performance of Feeder Cattle Fed Beef Oxidation Ditch Mixed
Liquor Combined with a Typical Finishing Ration 8
8 Comparison of Egg Production Levels of White Leghorn Hens
Receiving Tap Water and Aerobically Stabilized Laying Hen
Manure ..... 8
9 Composition and Calculated Analysis of Ration Fed to Birds
Producing the Manure Utilized for these Studies 14
10 Characteristics of Oxidation Ditch Mixed Liquor Utilized to
Initiate Batch and Continuous Flow Amino Acid Synthesis
Studies, mg/£ 15
11 Summary of Parameters Measured for Batch and Continuous Flow
Amino Acid Synthesis Studies 16
12 Characteristics of Laying Hen Manure Used in Batch and
Continuous Flow Studies 19
-vi11-
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Number Page
13 Amino Acid Composition of Laying Hen Manure During Batch
Aerobic Stabilization - Batch Study I 20
14 Amino Acid Composition of Laying Hen Manure During Batch
Aerobic Stabilization - Batch Study II 21
15 Changes in Concentrations, mg/£, of Total and Essential Amino
Acids with Time of Aeration - Batch Studies I and II 23
16 Amino Acid Composition of Laying Hen Manure as a Function of
Retention Time - Continuous Flow Studies 37
17 Comparison of the Amino Acid Composition of Aerobically
Stabilized and Freshly Excreted Laying Hen Manure with
Laying Hen Amino Acid Requirements 44
18 Comparison of the Amino Acid Composition of Aerobically Digested
Laying Hen Manure with Several Plant Protein Sources 45
19 An Estimate of the Monetary Value of Aerobically Stabilized
Laying Hen Manure as a Source of Protein Based on Projected
Feed Cost Savings 46
20 Design Example - A Completely Mixed, Continuous Flow
Aeration System for Enhancing the Nutritive Value of
Laying Hen Manure 49
-ix-
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LIST OF ABBREVIATIONS AND SYMBOLS
COD — Chemical Oxygen Demand
Kcal — Kilogram calorie
NH3~N — Ammonia Nitrogen
N02-N — Nitrite Nitrogen
N03-N — Nitrate Nitrogen
ODML — Oxidation Ditch Mixed Liquor
ODR — Oxidation Ditch Residue
ON — Organic Nitrogen
S0 — Initial Concentration
S-j — Concentration at a Specific Time
SRT — Solids Retention Time
TKN — Total Kjeldahl Nitrogen
TS — Total Solids
VS — Volatile Solids
-x-
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ACKNOWLEDGEMENTS
Financial support for this investigation was provided by the U.S.
Environmental Protection Agency under Grant No. R806140010 and the College
of Agriculture and Life Sciences, Cornell University. Mr. Lynn R. Shuyler;
U.S. Environmental Protection Agency, Ada, Oklahoma; served as the Project
Officer.
-xi-
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SECTION 1
INTRODUCTION
Results from several studies have indicated that aerobically stabilized
animal manures can have significant nutritive value when used as dietary
supplements for livestock and poultry. Results from these studies also have
indicated that aerobic stabilization can increase the nutritive value of
animal manures particularly as sources of amino acids. This investigation
was concerned with the amino acid transformations that occur as animal
manures are stabilized aerobically. The following paragraphs summarize the
results of previous research on this topic.
BACKGROUND
Interest in the possible nutritive value of aerobically stabilized
animal manures spans more than a decade. In one of the early studies
(Harmon jet_ £_1. , 1969), the value of aerobically stabilized swine manure
solids as a source of protein and energy was evaluated in a series of
feeding trials using weanling rats. The stabilized swine manure solids,
called oxidation ditch residue (ODR), were obtained by allowing oxidation
ditch mixed liquor (ODML) solids to settle and then removing and discarding
the supernatent.
The detailed results from this study, (Harmon et al., 1972), indicated
that the ODR had nutritive value as a source of both protein and energy.
Weight gains of the weanling rats were not decreased until ODR replaced more
than one-third to one-half of the castein or soybean meal in the control
diet. However, feed consumption per unit weight gain (gm feed/gm gain),
commonly referred to as feed efficiency, increased. This increase indicates
that the ODR was less digestible than the feedstuffs that were replaced.
The ODR was deficient in both lysine and tyrptophan which are essential
amino acids for rats. Additional details and results of this study are
summarized in Table 1.
Harmon et al. (1971) fed fortified corn-soybean meal diets containing
0.0%, 4.0%, U70T7 and 12.0% freeze dried swine ODML to weanling rats and
reported comparable weight gains and feed efficiencies for the 0.0% and 4.0%
diets. However, the diets containing 8.0% and 12.0% freeze dried swine ODML
decreased both weight gain and efficiency. The freeze dried ODML, which was
passed through a 20 mesh (841 micron opening) screen to remove hair, bran,
and other coarse solids, contained 41.5% protein and 1.27% lysine on a dry
matter basis.
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TABLE 1. PERFORMANCE OF WEANLING RATS FED OXIDATION DITCH RESIDUE* (ODR) IN
PLACE OF CASEIN, STARCH, OR SOYBEAN MEAL (Harmon et al., 1972).
Trial I. Substitution of
Casein, %
ODR, %
Avg. Daily Gain, Gm/day
Feed consumption, Gm/day
Feed/Gain, Gm/Gm
ODR for Casein.
20.0
0
6.5
14.4
2.2
16.7
10.3
6.5
15.4
2.4
13.3
20.6
6.1
17.3
2.8
10.0
31.0
5.3
17.8
3.4
Trial II. Substitution of ODR or Starch in Place of Casein.
Casein, %
Starch, %
ODR, %
Avg. Daily Gain, Gm/day
Feed consumption, Gm/day
Feed/Gain, Gm/Gm
10
0
5
16
2
16
.3
.3
.8
.6
.7
0
10
6
13
2
.3
.1
.8
.8
20
0
5
16
2
13
.6
.5
.5
.7
.3
0
20
5
14
3
.6
.6
.8
.0
31
0
4
15
3
10
.0
.8
.7
.1
.0
0
31.0
5.4
14.7
2.9
Trial III. Use of ODR in Corn Starch-Soybean Meal Diets,
Corn Starch, %
Soybean Meal, %
Lysine HCL, %
ODR, %
Avg. Daily Gain, Gm/day
Feed /Gain, Gm/Gm
22.8
27.2
0
0
4.8
2.7
11.9
13.6
0
24.5
5.3
3.3
1.0
0
0
49.0
0.9
16.1
0
0
1.0
49.0
0.3
50.0
Trial IV. Addition of Tryptophan and/or Lysine to a Basal Corn-ODR Diet.
Average Daily Feed per Gain
Diet Gain, Gm/Day Gm/Gm
Basal
Basal +0.1% Tryptophan
Basal +1.0% Lysine HCL
Basal +0.1% Tryptophan +
0.1% Lysine HCL
0.9
0.9
1.0
1.5
13.7
13.7
12.2
8.8
*Aerobically stabilized swine manure solids from an oxidation ditch.
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In a study evaluating alternatives for concentrating aerobically
digested swine manure solids for use as a feedstuff, Holmes et al. (1971)
found that over 80% of the suspended solids in swine ODML would pass through
a 200 mesh (74 micron opening) screen. It was suggested that this fraction,
described as being chocolate brown in color and gelatinous in consistency,
consisted primarily of microbial cells. With this material, as the particle
size decreased, the crude protein content (total Kjeldahl nitrogen x 6.25)
increased exponentially (Figure 1). This led to the conclusion that the
smaller size particles should have the greatest nutritive as sources of
protein. This conclusion was supported by a comparison of the concentra-
tions of several amino acids as a function of particle size (Table 2).
TABLE 2. AMINO ACID CONCENTRATION AS A FUNCTION OF PARTICLE SIZE*
FOR SWINE OXIDATION DITCH MIXED LIQUOR (Harmon, 1972).
Screen
Mesh
20
50
100
200
Size
Opening,
Micron
841
297
149
74
Percent of Dry
Lysine
0.38
0.92
1.36
3.08
Histidine
0.24
0.52
0.98
1.32
Threonine
0.98
1.57
2.01
2.44
Matter
Methionine
0.32
0.42
0.62
1.27
Isoleucine
0.81
1.13
1.66
2.20
*Particles passing through the noted size screen.
Harmon _et_ ^1_. (1973) found that swine ODML also had nutritive value
when used as a supplemental source of protein for feeder pigs. The perform-
ance of feeder pigs fed 12% protein corn-soybean meal diets mixed with tap
water and swine ODML were compared. The composition of the swine ODML used
is described in Table 3. The use of swine ODML significantly (P<0.05)
increased both average daily gain and feed efficiency (Table 4). The
researchers concluded that the observed improvement in animal performance
resulted from the correction of a marginal amino acid deficiency. The
addition of the swine ODML resulted in a 0.1% increase in the lysine content
of the diet. Protein content was increased by 2.5%.
No signficant differences were observed, however, when the performance
of feeder pigs fed corn plus ODML versus corn plus tap water diets were
compared (Table 4). The results of these two feeding trials indicate that
aerobically stabilized manures can have value as a supplemental but not a
primary source of protein.
Noting that a pig normally consumes twice as much water as dry feed,
Harmon and Day (1974) compared the performance of feeder pigs receiving tap
water and swine ODML as a tap water substitute. They found that using ODML
-------
100 r
85
UJ
80
75.6
Z
UJ
c
60
40
UJ
o
g 20
o
841
412
20.0
8.4 r
n n
297
14.6
250
149
74
>T4
SCREEN OPENINGS, MICRONS
Figure 1.
Crude protein content as a function of particle size
for swine oxidation ditch mixed liquor.
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TABLE 3. COMPOSITION OF SWINE OXIDATION DITCH MIXED LIQUOR USED BY
HARMON ETAL. (1973) IN FEEDING TRIALS INVOLVING FEEDER PIGS.
Component
Protein
Lysine
Histidine
Arginine
Threonine
Valine
Isoleucine
Leucine
Methionine
Aspartic Acid
Serine
Glutamic Acid
Proline
Glycine
Alanine
Tyrosine
Tryptophan
Calcium
Phosphorus
Magnesium
Sodium
Potassium
%, Dry Matter Basis*
49.0
1.42
0.47
1.28
1.96
2.06
1.49
2.79
0.77
3.73
2.55
5.06
1.29
2.29
2.83
1.17
0.28
3.33
3.83
1.49
2.75
4.14
*Dry matter averaged 3.40%.
TABLE 4. PERFORMANCE OF FEEDER PIGS FED 12% PROTEIN CORN-SOYBEAN
MEAL AND CORN DIETS COMBINED WITH SWINE OXIDATION DITCH
MIXED LIQUOR AND TAP WATER (Harmon et al., 1973).
Average Daily Gain, kg
Corn-Soybean Meal
Water ODML
0.52 0.56*
Corn
Water
0.32
ODML
0.34
Feed Consumed per Unit
Gain, kg/kg 4.02 3.76* 5.59 5.38
*Differences are significant (P < 0.05).
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in place of tap water in combination with a 12% protein corn-soybean meal
diet also improved average daily gain and feed efficiency (Table 5). These
results are particularly interesting because of the simplicity of the
utilization approach. Using aerobically stabilized manure as a tap water
substitute eliminates the need to mix feed daily as well as possible feed
spoilage problems.
Harmon and Day (1974) presented a comparison of concentrations of
several essential amino acids present in swine oxidation ditch mixed liquor
and in fresh and dried swine feces (Table 6). This comparison, in combina-
tion with the observation that the concentrations of several amino acids
increased substantially as particle size decreased (Table 2), formed the
basis for suggesting that the nutritive value of swine manure is upgraded
microbially during aerobic digestion.
In a recent study, Frank £t_ J_l• (1980) utilized swine ODML as a tap
water substitute for feeder pigs in combination with diets deficient in
vitamins, calcium and phosphorus, or protein. The use of ODML in place of
tap water did not improve weight gain or feed efficiency when used in com-
bination with either 12% or 14% protein corn-soybean meal diets. The ODML
did not correct vitamin or calcium and phosphorus deficiencies. The results
of this study were confounded, however, by high ODML nitrate nitrogen con-
centrations which ranged from 44 mg/£ to 1600 mg/£. In previous studies,
nitrate nitrogen concentrations normally ranged between 70 mg/i and 225 mg/£
and never exceeding 370 mg/Jl (Harmon and Day, 1975). The high nitrate
nitrogen concentrations in the diet could have affected the performance of
the animals.
Feeding trials also have been conducted to assess the nutritive value
of aerobically stabilized beef cattle and laying hen manures. Vetter (1972)
combined beef ODML with a typical finishing ration and fed the mixture to
feeder cattle. The results of the three feeding trials (Table 7) showed
that the use of beef ODML had no consistent impact on either weight gain or
feed efficiency. The statistical significance of the observed differences
was not reported.
Hegg et^ _al_. (1974) fed settled solids obtained from a beef cattle oxi-
dation ditch to feeder steers as a partial replacement for ground corn. It
was concluded, based on observed animal performance, that this material had
between 63% and 85% of the nutritive value of ground corn. This estimate
was reduced to 50% based on the results of a subsequent feeding trial (Hegg
et_aL , 1975).
Martin (1980) reported a statistically significant (P<0.01) increase in
egg production when aerobically stabilized poultry manure was used as a tap
water substitute for White Leghorn laying hens (Table 8). No significant
differences in either egg quality or bird health were observed. In this
study both control and experimental groups of birds received a typical 17%
protein laying ration.
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TABLE 5. PERFORMANCE OF FEEDER PIGS FED SWINE OXIDATION DITCH MIXED
LIQUOR AS A TAP WATER SUBSTITUTE IN COMBINATION WITH A 12%
PROTEIN CORN-SOYBEAN MEAL DIET. (Harmon and Day, 1974).
Replicate*
1
2
3
4
5
6
X
Avg. Daily
Tap Water
0.61
0.66
0.77
0.60
0.58
0.71
0.66
Gain, kg
ODML
0.63
0.70
0.90
0.72
0.66
0.79
0.73
Feed/Gain,
Tap Water
3.30
3.38
4.10
4.35
3.85
3.23
3.70
kg/kg
ODML
3.25
3.37
2.92
3.60
3.80
2.96
3.32
*Each replicate represents results, from 10 pigs.
TABLE 6. COMPARISON OF THE AMINO ACID COMPOSITION OF SWINE OXIDATION DITCH
MIXED LIQUOR AND FRESH AND DRIED SWINE FECES (Harmon & Day, 1974).
Ami no Acid
Phenylalanine
Lysine
Arginine
Threonine
Methionine
Isoleucine
Leucine
*Gouwens (1966)
tOrr et al. (1973)
§Harmon et al . (1972)
Fresh
Swine
Feces*
0.81
0.60
0.44
0.53
—
0.52
0.92
Dried
Swine
Fecest
0.87
1.11
0.67
0.80
0.58
1.03
1.57
...
of Dry Matter™"
Oxidation
Ditch Mixed
Liquor§
1.48
1.42
1.28
1.96
0.77
1.49
2.79
Oxidation
Ditch Mixed
Liquort
1.66
1.60
1.45
1.22
0.60
1.54
2.13
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TABLE 7. PERFORMANCE OF FEEDER CATTLE FED BEEF OXIDATION DITCH MIXED
LIQUOR COMBINED WITH A TYPICAL FINISHING RATION (Vetter, 1972).
Trial
Treatment
Avg. Daily
Gain, kg
Ration Fed,
kg Dry Matter
ODML Fed,
kg Dry Matter
Ration Fed
per Unit Gain, kg/kg
I (133 Days)
Control ODML
1.58 1.59
10.10 10.95
0.23*
6.39 6.66
II (111 Days)
Control ODML
1.30 1.36
9.33 9.52
0.41
7.18 7.00
III (119 Days)
Control ODML
1.38 1.30
9.78 8.84
0.32
7.09 6.80
*Average, 0.37 for final 49 days.
TABLE 8. COMPARISON OF EGG PRODUCTION LEVELS OF WHITE LEGHORN HENS
RECEIVING TAP WATER AND AEROBICALLY STABILIZED LAYING HEN
MANURE (Martin, 1980).
Egg Production, Hen-Day Percent
Trial
I
II
III
Duration,
Months
6
8
8
Tap Water
66.6
76.7
77.2
Aerobically Stabilized
Laying Hen Manure
68.6
79.8
80.0
Differential,
Percent*
+2.0
+3.1
+1.3
*Differences in average egg production within each trial are significant
(P < 0.01).
-------
The use of aerobically stabilized poultry manure as a tap water substi-
tute for laying hens also has been evaluated by Johnson _et_ j_l. (1977).
However, mixed liquor nitrate nitrogen concentrations were not controlled in
the study and reached 1300 mg/£. As a result, egg production, on a hen-day
basis, decreased from 64.7% for the first week of the study to 1% during
week seven.
PROJECT OBJECTIVES
The results of the studies summarized in the preceding discussion have
demonstrated that aerobically stabilized livestock and poultry manures have
nutritive value and can be utilized successfully as supplemental sources of
protein and energy. However, the underlying hypothesis, that aerobic stabi-
lization enhances the nutritive value of manures particularly as sources of
amino acids, has received little attention. Although Harmon and Day (1974)
have shown that concentrations of several essential amino acids are much
greater in aerobically stabilized swine manure as compared to freshly
excreted swine manure (Table 6), the nature of the transformations respon-
sible for these increases is unknown. Since these comparisons were made on
a dry matter basis, it is possible that the increases only result from
solids destruction rather than microbial amino acid synthesis. In addition,
the potential for utilizing aerobic stabilization to maximize the nutritive
value of manures is unknown. Aerobically stabilized manures have been used
as feedstuffs on an "as available" basis.
This investigation evaluated the potential of aerobic stabilization to
increase the value of laying hen manure as a feedstuff. Specific objectives
included:
1. Determination of the nature of the amino acid transformations that
occur as laying hen manure is stabilized aerobically.
2. Evaluation of solids retention time (SRT) as an aeration system
design and operating parameter for maximizing amino acid content
and quality.
3. Characterization of the relationship between amino acid
transformations and waste stabilization.
-------
SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS
From the results of these studies, it can be concluded that:
1. Aerobic stabilization has merit as a process for: (a) reducing the
air (odor) and water pollution potential of laying hen manure and
(b) enhancing the essential amino acid content and thus the poten-
tial value of laying hen manure as a feedstuff.
2. Short-term aeration (3-4 days) significantly increases the essen-
tial amino acid content and thus the potential value of laying hen
manure as a feedstuff.
3. Long-term aeration (>3-4 days): (a) reduces the value of aerobic-
ally stabilized laying hen manure as a source of amino acids and
(b) provides little additional benefit to stabilization.
4. Solids retention time (SRT) can be used as a basis for system
design and process control for both amino acid enhancement and
waste stabilization.
5. The potential value of aerobically stabilized laying hen manure as
a feedstuff appears adequate to justify the use of aeration for
waste stabilization and odor control.
6. The use of aerobic stabilization to enhance the nutritive value of
livestock and poultry manures as feedstuffs has merit and deserves
further study.
RECOMMENDATIONS
It is recommended that:
1. Laboratory scale continuous flow studies be conducted using laying
hen manure as a substrate to characterize the nature of amino acid
transformations that occur at solid retention times of less than
three days.
10
-------
2. Digestibility studies using established methodology be conducted to
determine araino acid availability and the value of aerobically
stabilized laying hen manure with high amino acid concentrations as
a source of energy.
3. The question of ammonia toxicity when aerobically stabilized laying
hen manure is used as a feedstuff should be examined since the
short retention times necessary to maximize essential amino acid
content precludes nitrification.
4. Long term feeding trials should be conducted comparing animal
performance with nutritionally complete and marginally deficient
diets supplemented with aerobically stabilized laying hen manure
containing high amino acid concentrations. Results of digestibi-
lity studies should be used in combination with established feed
formulation practices to formulate experimental diets. Both egg
production and feed conversion efficiency should be used as cri-
teria for assessing animal performance.
11
-------
SECTION 3
METHODS AND MATERIALS
In order to characterize and quantify the amino acid transformations
that occur as animal manures are stabilized aerobically, laboratory scale
batch and continuous flow studies were conducted using laying hen manure as
the substrate. Four liter glass serum bottles were used as reactors for
both batch and continuous flow studies. Compressed air was supplied con-
tinuously via fritted gas dispersion tubes at rates necessary to maintain
measurable dissolved oxygen concentrations (>0.5 mg 02/&) in the reactors at
all times. The mixing action of the compressed air was supplemented using
magnetic stirrers and teflon coated stirring bars to maintain completely
mixed conditions. Equipment details are sketched in Figure 2. All studies
were conducted at ambient laboratory temperatures of 20 ± 2°C.
The manure utilized in these studies was collected from caged White
Leghorn laying hens housed at the Agricultural Waste Management Laboratory,
Cornell University. The birds were of the Shaver strain and received a
typical laying ration (Table 9) containing 2930 Real metabolizable energy/kg
of feed.
The manure used for these studies was collected over 24 hour time
periods by suspending a tray below an individual cage containing three
birds. Collection periods were limited to 24 hours to minimize chemical and
microbial transformations prior to utilization. Following removal of
extraneous materials, primarily wasted feed and feathers, the collected
manure was either refrigerated at 4eC or frozen for long term storage and
subsequent use.
Mixed liquor from a pilot plant scale oxidation ditch stabilizing poul-
try manure was used as the source of an active, adapted microbial population
for both batch and continuous flow studies. The chemical and physical
characteristics of the mixed liquor used for each study are summarized in
Table 10. The absence of both ammonia and nitrate nitrogen is the result of
intermittent aeration in the oxidation ditch to achieve simultaneous nitri-
fication and denitrification.
12
-------
VENT
FRITTED GAS
DISPERSION TUBE
HUMIDIFIED
COMPRESSED AIR
FLOW METER
4 I GLASS STERUM
BOTTLE
STIR BAR
MAGNETIC STIRRER'
Figure 2. Schematic of reactors and ancillary equipment used
for batch and continuous :flow studies.
13
-------
TABLE 9. COMPOSITION AND CALCULATED ANALYSIS OF RATION FED TO
BIRDS PRODUCING THE MANURE UTILIZED FOR THESE STUDIES,
Amount
Composition (kg/tonne)
No. 2 Yellow Corn Meal 685
Stabilized Grease 10
Soybean Meal, Dehulled, 49% Protein 140
Corn Distillers Solubles with Grains 15
Meat and Bone Meal 60
Alfalfa Meal 10
Limestone 35
Oyster Shell ' 40
Salt, Iodized 2
Sodium Sulfate 0.5
Vitamin and Mineral Premix 2.5
Calculated Analysis: (%)
Protein 16.1
Fat 4.4
Fiber 2.2
Calcium 3.47
Available Phosphorus 0.42
Linoleic Acid 1.48
Lysine 0.76
Methionine 0.36
Metabolizable Energy, Kcal/kg 2930
BATCH STUDIES
Separate batch studies were conducted for periods of 15 and 10 days,
respectively. For each of these studies, an appropriate quantity of fresh
laying hen manure was diluted with distilled water to produce 5.4 I of
slurry that contained approximately 30 gm total solids/i to which 0.6 £ of
oxidation ditch mixed liquor was added. Following mixing, the resultant
mixture was divided into two equal parts and placed in separate reactors
that were operated simulatneously.
Reactor contents were analyzed on days 0, 1, 2, 3, 4, 7 and 15 for
Batch Study I and on days 0, 1, 2, 2.5, 3, 3.5, 4, 7 and 10 for Batch Study
II for the parameters indicated in Table 11. Corrections for evaporative
losses using distilled water were made daily. Dissolved oxygen measurements
also were made daily to insure that a residual concentration was present.
14
-------
TABLE 10. CHARACTERISTICS OF OXIDATION DITCH MIXED LIQUOR UTILIZED TO INITIATE
BATCH AND CONTINUOUS FLOW AMINO ACID SYNTHESIS STUDIES, mg/£.
Batch Studies
I
II
i-1
*-" Continuous Flow Studies
3 and 10 Day HRT
5 Day HRT
7 Day HRT
Total
Solids
25,180
15,160
28,800
23,990
20,360
Volatile
Solids
15,640
9,390
17,910
14,920
12,340
Total Kjeldahl
Nitrogen
1510
710
1570
1270
1030
Ammonia
Nitrogen
Trace
0
0
0
0
Nitrite
Nitrogen
Trace
0
0
0
0
Nitrate
Nitrogen
Trace
175
0
0
0
PH
8.1
7.5
8.0
7.9
8.0
-------
TABLE 11. SUMMARY OF PARAMETERS MEASURED FOR BATCH AND CONTINUOUS FLOW AMINO ACID SYNTHESIS STUDIES.
Total Solids (TS)
Volatile Solids (VS)
Total Kjeldahl Nitrogen (TKN)
Ammonia Nitrogen (NHa-N)
Nitrite Nitrogen (N02~N)
Nitrate Nitrogen (N03-N)
Chemical Oxygen Demand (COD)
pH
Temperature
Oxygen Uptake Rate
Gross Energy
Ami no Acids
Batch Study I
X
X
X
X
X
X
X
X
X
X
X
X
Batch Study II
X
X
X
X
X
X
X
X
X
X
X
X
Continuous Flow Studies
Fresh Manure Effluent
X X
X X
X X
X
X
X
X X
X X
X
X
X X
-------
CONTINUOUS FLOW STUDIES
Continuous flow reactors were operated at retention times of 3, 5, 7
and 10 days without solids recycle. Thus, hydraulic and solid retention
times were equal. The reactors initially were filled with oxidation ditch
mixed liquor (Table 10). Each day, a volume of mixed liquor appropriate to
achieve the respective retention time was removed and replaced with a com-
parable volume of fresh laying hen manure diluted with distilled water to
form a slurry containing 30 gm total solids/A. Each reactor was operated
for a period equivalent to three retention times to establish steady state
conditions before reactor contents were analyzed for the physical and chemi-
cal characteristics indicated in Table 11. The fresh manure utilized as
substrate also was analyzed for the same characteristics (Table 11) to per-
mit determination of material balances and to characterize transformations
of various constituents, particularly amino acids. The dissolved oxygen
concentration was measured daily to insure that aerobic conditions were
maintained.
ANALYTICAL METHODS
For this study, the following analytical techniques were utilized:
total and volatile solids and chemical oxygen demand (Standard Methods,
1975); total Kjeldahl nitrogen - microKjeldahl method (McKenzie and Wallace,
1954); nitrate nitrogen - diazotization method (Montgomery and Dymock,
1961); and ammonia and nitrate nitrogen - steam distillation and salicylic
methods, respectively (Prakassam et_ al_. , 1975).
Dissolved oxygen concentrations and temperature were measured with a
Yellow Springs Instrument Company Model 54 oxygen meter. Oxygen uptake
rates were determined using the method described by Loehr, 1977. A combina-
tion Ag/Ag Cl glass electrode with an Orion lonanalyzer was used for pH
measurements.
Samples for amino acid and gross energy determinations were frozen and
freeze dried. The freeze dried samples were ground using a Wiley mill with
a 40 mm mesh screen. Gross energy determinations were made using an
adiabatic bomb colorimeter. Amino acid analyses were performed by personnel
of the Amino Acid Analysis and Protein Sequencing Facility, College of
Veterinary Medicine, Cornell University. Samples were hydrolyzed using 6 N
hydrochloric acid for 24 hours at 110°C prior to analysis by a Beckman 119CL
Amino Acid Analyzer equipped for single column analysis of hydrolysates.
Each sample was analyzed for the following amino acids: alanine, arginine,
aspartic acid, glutamic acid, glycine, histidine, isoleucine, leucine,
lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, and
valine.
17
-------
SECTION 4
RESULTS
The following summarizes the results of the batch and continuous flow
studies described in Section 3.
RAW WASTE CHARACTERISTICS
The characteristics of the laying hen manure used as substrate for both
batch and continuous flow studies are summarized in Table 12. Although
there was some variation between individual manure samples, these differ-
ences were assumed to be primarily the result of sampling and analytical
variations. Thus, the means presented in Table 12 were used as the basis
for all material balances presented and discussed in subsequent paragraphs.
BATCH STUDIES
As noted in Section 3, two independent batch studies were conducted.
The first, Batch Study I, was conducted for 15 days and Batch Study II for
10 days. Since the results from the two studies are similar, they are pre-
sented together. As initial concentrations of amino acids and other para-
meters of interest differed slightly, the format of expressing a concentra-
tion at a specific time, S-p, as a fraction of the initial concentration,
So, i.e. ST/SQ, to compare results from the two studies will be used
as appropriate.
Results of the amino acid analyses performed during each study are
summarized in Tables 13 and 14. These data show that the composition of
laying hen manure amino acids changed substantially during the initial peri-
od, 3 to 4 days, of aeration. One result of these changes was a significant
increase in essential amino acids expressed as a percentage of total amino
acids. Another result was an apparent increase in amino acid quantity. The
term apparent is used because expressing amino acid content as a percentage
of initial total solids reflects not only possible microbial increases in
the mass of amino acids present but also the biological destruction of total
solids.
As shown in Figure 3, substantial reductions (up to 50%) in mixed
liquor concentrations of total and volatile solids occurred in each batch
study. Results of calculations to convert the amino acid concentrations
presented as percentages of total solids (Tables 13 and 14) to a mass-
volume, rng/A, basis (Table 15) show that the previously noted increases
18
-------
TABLE 12. CHARACTERISTICS OF LAYING HEN MANURE USED
IN BATCH AND CONTINUOUS FLOW STUDIES.
Parameter Mean Std. Dev.
Total Solids (TS), %
Volatile Solids (VS), % of Total Solids
20.7
74.3
1.3
3.5
15
15
Total Kjeldahl Nitrogen (TKN),
mg TKN/gm TS 89.3 8.1 15
Chemical Oxygen Demand (COD),
mg COD/gm TS 823. 88. 12
Amino Acids, (AA), mg AA/gm TS
As par tic Acid
Threoninet
Serine
Glut ami c Acid
Procine
Glycine
Alanine
Valinet
Methioninet
Isoleucinet
Leucinet
Tyros ine
Phenylalaninet
Histidinet
Lysinet
Argininet
Total Amino Acids
Essential Amino Acids
14.1
6.0
6.0
17.2
7.0
38.1
10.6
7.0
2.4
9.0
9.4
3.6
4.9
2.8
7.0
6.0
151.0
54.4
1.2
0.9
0.6
1.4
0.5
5.4
0.7
0.7
0.2
1.7
0.7
0.4
0.3
0.2
0.5
0.7
11.8
2.5
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
* n = number of observations.
t amino acids essential for the chicken.
19
-------
TABLE 13. AMINO ACID COMPOSTION OF LAYING HEN MANURE DURING BATCH AEROBIC STABILIZATION -
BATCH STUDY I.
N)
o
Araino Acid, % TS.*
Alanine
Argininet
Aspartic Acid
Glutamic Acid
Glycine
Histidinet
Isoleucinet
Leucinet
Lysinet
Methioninet
Phenylalaninet
Proline
Serine
Threoninet
Tyrosine
Valinet
Total Amino Acids
Essential Amino Acids,
% of Total
0
0.79
0.56
1.23
1.51
1.90
0.15
0.59
0.85
0.65
0.26
0.48
0.59
0.51
0.52
0.35
0.66
11.60
40.7
1
1.07
0.78
1.61
1.96
1.93
0.31
0.76
1.17
0.93
0.36
0.65
0.67
0.65
0.69
0.49
0.96
14.99
44.1
2
1.14
0.80
1.66
1.97
0.99
0.30
0.79
1.22
0.92
0.38
0.69
0.69
0.67
0.74
0.50
1.00
14.46
47.3
3
1.31
0.92
1.82
2.19
1.05
0.32
0.96
1.37
1.03
0.49
0.75
0.76
0.77
0.80
0.57
1.11
16.22
47.8
4
1.26
0.88
1.74
2.09
1.03
0.30
0.92
1.28
0.96
0.47
0.71
0.75
0.76
0.77
0.53
1.03
15.48
47.3
7
1.19
0.85
1.59
1.91
1.02
0.27
0.80
1.17
0.79
0.42
0.66
0.77
0.71
0.73
0.47
0.95
14.30
46.4
15
0.97
0.64
1.22
1.45
0.84
0.19
0.65
0.94
0.48
0.15
0.51
0.62
0.52
0.59
0.21
0.74
10.72
45.6
* % of total solids (dry matter).
t essential amino acids.
-------
TABLE 14. AMINO ACID COMPOSTION OF LAYING HEN MANURE DURING BATCH AEROBIC STABILIZATION -
BATCH STUDY II.
Amino Acid, % TS*
Alanine
Argininet
Aspartic Acid
Glutamic Acid
Glycine
Histidinet
Isoleucinet
Leucinet
Lysinet
Methioninet
PhenylalanineT
Proline
Serine
Threoninet
Tyrosine
Valinet
Total Amino Acids
Essential Amino Acids,
% of Total
0
0.93
0.53
1.22
1.43
3.03
0.27
0.67
0.90
0.61
0.25
0.50
0.60
0.49
0.53
0.35
0.65
12.96
37.9
1
0.88
0.62
1.38
0.92
1.80
0.29
0.73
1.05
0.73
0.27
0.59
0.57
0.51
0.59
0.43
0.78
12.67
44.5
2
1.14
0.85
1.80
2.04
1.08
0.36
0.98
1.37
0.97
0.43
0.76
0.73
0.67
0.77
0.59
1.02
15.56
48.3
"•"• i line o
2.5
1.38
0.99
1.95
2.28
1.15
0.37
1.12
1.56
1.08
0.33
0.87
0.81
0.76
0.88
0.63
1.19
17.32
48.4
f Aeratic
3
1.27
0.93
1.86
2.14
1.09
0.35
1.09
1.48
1.00
0.29
0.83
0.78
0.74
0.83
0.61
1.13
16.42
48.3
>n, Days
3.5
1.36
0.99
1.97
2.29
1.14
0.37
1.15
1.56
1.08
0.30
0.88
0.81
0.77
0.89
0.63
1.19
17.38
48.4
4
1.38
1.02
2.01
2.34
1.15
0.37
1.18
1.56
1.12
0.31
0.88
0.81
0.80
0.92
0.65
1.19
17.67
48.3
7
1.28
0.92
1.79
2.14
1.07
0.32
0.99
1.35
0.86
0.32
0.77
0.77
0.75
0.83
0.51
1.06
15.73
47.2
10
1.27
0.92
1.73
2.04
1.08
0.31
1.06
1.41
0.79
0.25
0.73
0.79
0.75
0.82
0.44
1.03
15.42
47.5
* % of total solids (dry matter).
t essential amino acids.
-------
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Figure 3.
A
S
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12
15
TIME OF AERATION, DAYS
Mixed liquor total and volatile solids concentrations,
expressed as fractions of initial concentrations, as a
function or aeration time during batch aerobic stabilization.
22
-------
t-o
LO
TABLE 15. CHANGES IN CONCENTRATIONS (MG/A) OF TOTAL AND ESSENTIAL AMINO ACIDS WITH TIME OF AERATION -
BATCH STUDIES I AND II.
Time of Aeration,
Days
0
1
2
2.5
3
3.5
4
7
10
15
Total Araino
Acids, mg/£
4170
4910
4518
—
4919
—
4606
3522
—
2434
Essential Amino
Acids*, mg/£
1697
2165
2137
—
2351
—
2179
1634
—
1110
Total Amino
Acids, mg/£
3926
3613
3941
4161
3843
3866
3713
3004
2715
—
Essential Amino
Acids*, mg/Jl
1488
1608
1904
2014
1856
1871
1793
1418
1290
—
*Amino acids essential for the chicken.
-------
largely are apparent reflecting total solids destruction. Although actual
increases in amino acid concentrations on a mg/Jl basis were, at best, nomin-
al (Table 15 and Figure 4), there were substantial increases in essential
amino acid concentrations in both studies (Table 15 and Figure 5). These
increases occurred during the initial phase, 2.5 to 3 days, of aeration in
both studies.
The declines in both total and essential amino acid concentrations
after about four days (Figures 4 and 5) appear to be the result of endogen-
ous respiration. It should be noted that the percent of essential amino
acids did not decline appreciably during this period (Tables 13 and 14).
In both studies, mixed liquor gross energy concentrations, Kcal/Z,
declined with time (Figure 6) reflecting decreases in mixed liquor volatile
solids concentrations (Figure 3). However, slight increases in the gross
energy content of the remaining volatile solids were observed in both stud-
ies with maximum levels achieved during the first 2 to 3 days of aeration
(Figure 7).
As illustrated in Figure 3, significant reductions in mixed liquor
volatile solids concentrations occurred in both batch studies. These
reductions are indicative of the microbial oxidation of biodegradable
carbonaceous compounds producing carbon dioxide and water as end-products.
Thus, volatile solids destruction is a useful parameter to characterize
stabilization. However, not all carbonaceous compounds contained in laying
hen manure are readily biodegradable (Martin and Loehr, 1977). To provide
a more accurate basis for examining the relationship between manure stabili-
zation and amino acid transformations during aerobic digestion, the methodo-
logy developed by Foree and McCarty (1968) was used to determine the bio-
degradable and refractory fractions of the manure used in these studies.
Using volatile solids data from both batch studies, it was determined that
only about 50% of the volatile solids in the initial laying hen manure used
in the studies were readily biodegradable (Figure 8).
As shown in Figure 9, destruction of biodegradable volatile solids was
essentially complete in both studies after 10 days of aeration with over 50%
of the destruction occurring within the first three days. Decreases in
oxygen uptake rates (Figure 10) and chemical oxygen demand (Figure 11) also
indicate that stabiliztion was essentially complete in 10 days.
In these studies, nitrogen transformations were of interest due to the
possibility of competition between the heterotrophic microbial population
and the nitrifying bacteria, Nitrosomas and Nitrobacter, for ammonia nitro-
gen. However, the presence of residual ammonia nitrogen concentrations
through day 10 in both studies indicated that amino acid synthesis was not
limited by available nitrogen. Although the oxidation ditch mixed liquor
used to seed the batch units contained active nitrifying bacteria, evidence
of nitrification, i.e., the presence of either nitrite or nitrate nitrogen,
was not observed in either study until day 4 of aeration. Figure 12 shows
the changes of ammonia and oxidized forms of nitrogen that are representa-
tive of both studies. The large initial increase in the concentration of
ammonia nitrogen in both Study I (Figure 12) and in Study II, reflects the
24
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Figure 4.
Mixed liquor amino acid concentrations, expressed as
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Mixed liquor essential amino acid concentrations, expressed
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0 BATCH STUDY I
A BATCH STUDY II
369
TIME OF AERATION, DAYS
12
Figure 9.
Reduction of the biodegradable fraction of laying
hen manure volatile solids as a function of aeration
time during batch aerobic stabilization.
29
-------
£
> 5
&
|
I 4
uf 3
or
UJ
X. 2
-------
24
•s
e 20
LJ
Q
UJ
>
X
o
u
2
UJ
o
16
8
I
3 6 9
TIME OF AERATION, DAYS
12
Figure 11.
Mixed liquor chemical oxygen demand as a function
of time of aeration — batch study II.
31
-------
9
8
1000 -
800 -
Z 600 -
<
QC
Ul
O
400
2OO -
16
TIME OF AERATION, DAYS
Figure 12. Mixed liquor concentrations of ammonia and oxidized
forms of nitrogen — batch study I.
-------
rapid microbial degradation of organic nitrogen, ammonification, which
occurred during the first 3 days of aeration (Figure 13).
Although amino acid nitrogen constituted a relatively constant fraction
of initial total nitrogen during the first three days of aeration (Figure
14), it became an increasingly larger fraction of the remaining organic
nitrogen during this period (Figure 15). This is indicative of an increase
in the potential value of the remaining organic nitrogen as a source of
protein.
CONTINUOUS FLOW STUDIES
Following the completion of the two batch studies, continuous flow
condition studies were undertaken. The continuous flow reactors were
operated at solids retention times (SRTs) of 3, 5, 7 and 10 days. The
following summarizes the results obtained under steady-state conditions.
Results of analyses to determine amino acid content and composition for
each retention time are compared with influent values in Table 16. These
data show changes in amino acid composition similar to those observed in the
two batch studies (Tables 13 and 14). The percent of essential amino acids
were greater in units having the shorter SRT values.
As shown in Figure 16, the apparent increases in amino acids at SRTs of
3 and 5 days (Table 16) were due to decreases in mixed liquor total solids
concentrations (Figure 17). Even with short term aeration, 3 day SRT, the
mixed liquor concentration, mg/£, of total amino acids decreased slightly
(Figure 16) although there was an increase in the concentration of essential
amino acids. At retention times'exceeding 3 days, concentrations of both
total and essential amino acids decreased rapidly. Thus aerobic stabiliza-
tion units with long SRT values (>3 days) will have lower amino acid concen-
trations in the mixed liquor.
Changes in mixed liquor concentrations of total and volatile solids
(Figure 17) and chemical oxygen demand (Figure 18) as a function of reten-
tion time indicate that retention times exceeding 3 days provide little
additional benefit with respect to waste stabilization. This conclusion
also is supported by the observed decrease in oxygen uptake rates as SRT
increases (Figure 19).
As shown in Figure 20, the retention time of 3 days was not adequate to
maintain an active population of nitrifying bacteria as indicated by the
lack of either nitrite or nitrate nitrogen. This was not unexpected, how-
ever, since reported minimum SRT values for Nitrosomonas and Nitrobacter at
20°C are 2.1 days and 2.9 days, respectively (Stratton and McCarty, 1967).
As shown in Figure 21, mixed liquor organic nitrogen consisted almost
entirely of amino acid nitrogen at a retention time of 3 days but the amino
acid fraction declined as retention time increased.
33
-------
o>
E
LU
O
o
GC
2600
2200
1800 -
O BATCH STUDY I
BATCH STUDY II
p 1400 -
o
cc
o
1000 -
600 -
369
TIME OF AERATION, DAYS
12
Figure 13i
Mixed liquor organic nitrogen as a function of
aeration time — batch studies.
34
-------
^g
-o
z tr
9H
Q-J
4°
O — 30-k-
20
Ot 10
O A g A
O
O BATCH STUDY I
A BATCH STUDY II
A
O
12
TIME OF AERATION, CMXYS
Figure 14.
Amino acid nitrogen, expressed as a percentage
of initial total nitrogen, as a function of
aeration time — batch studies.
15
-------
IUU
u_
o
FROGEN, %
IITROGEN
a> co
0 0
Si 40
< g
o £ <
z o
2 20
0
(
A
O
0
A A o
O O
O
i A 0 BATCH STUDY I
> A BATCH STUDY II
i i i i i
D 3 6 9 12 15
TIME OF AERATION, DAYS
Figure 15. Amino acid nitrogen, expressed as a percentage
of mixed liquor organic nitrogen, as a function
of aeration time — batch studies.
-------
TABLE 16. AMINO ACID COMPOSTION OF LAYING HEN MANURE AS A FUNCTION OF RETENTION TIME
CONTINUOUS FLOW STUDIES.
Amino Acid, % TS*
Alanine
Argininet
Aspartic Acid
Glutamic Acid
Glycine
Histidinet
Isoleucinet
Leucinet
Lysinet
Methioninet
Phenylalaninet
Proline
Serine
Threoninet
Tyrosine
Valinet
Total Amino Acids
Essential Amino Acids,
% of Total
Influent
1.06
0.60
1.41
1.72
3.81
0.28
0.90
0.94
0.70
0.24
0.49
0.70
0.60
0.60
0.36
0.70
15.10
36.0
3 5
2.11
1.26
2.37
2.70
1.70
0.36
1.19
1.63
1.13
0.55
0.86
0.94
0.96
1.04
0.62
1.34
20.76
45.1
1.74
0.56
1.97
2.08
1.56
0.29
1.01
1.42
0.61
0.25
0.72
0.80
0.78
0.83
0.44
1.21
16.27
42.4
7
1.54
0.92
1.73
1.81
1.39
0.28
0.91
1.35
0.44
0.33
0.66
0.78
0.65
0.67
0.37
1.10
14.93
44.6
10
0.78
0.42
0.84
0.88
0.54
0.11
0.43
0.73
0.35
0.01
0.13
0.62
0.08
0.04
0.00
0.63
6.59
43.2
* % of total solids (dry matter).
t essential amino acids.
-------
5000 r
4000
3000
cn
o
< 2000
<
1000
AM I NO ACIDS
ESSENTIAL
AMI NO ACIDS
0
. Figure 16.
6
12
o
f
z
UJ
u
8
10
RETENTION TIME, DAYS
Relationships between total and essential
amino acid concentrations and retention
time — continuous flow studies.
TOTAL SOLIDS
VOLATILE SOLIDS
> 3 6 9 12
RETENTION TIME, DAYS
Figure 17. Relationships between total and volatile
solid concentrations and retention time —
continuous flow studies.
38
-------
o
9
Figure 18.
RETENTION TIME, DAYS
Relationship between mixed liquor chemical
oxygen demand concentrations and retention
time — continuous flow studies.
UJ .
E
o -
o uj
UJ *
Q.
60 r
40
20
6
RETENTION TIME, DAYS
12
Figure 19.
Relationship between oxygen uptake rates
and retention time — continuous flow studies,
39
-------
9
7
o
800
600
400
200
z z
I I
hJ?
z
O
*r
5 7
RETENTION TIME, DAYS
10
Figure 20. Mixed liquor concentrations of organic, ammonia,
nitrite, and nitrate nitrogen — continuous
flow studies.
-------
100 r
RETENTION TIME, DAYS
Figure. 21. Relationship between amino acid nitrogen
expressed as a percentage of organic
. nitrogen and retention time — continuous
flow studies.
41
-------
SUMMARY
The results of these studies indicate that short term aerobic stabili-
zation, about three days under batch conditions and at a retention time of
three days or less under continuous flow conditions, significantly enhances
the value of laying hen manure as a source of essential amino acids. These
results also show that the stabilization of readily biodegradable carbon-
aceous compounds present as constituents of laying hen manure is essentially
complete within three days of aertion. Thus, waste stabilization and amino
acid enhancement can be complementary objectives.
42
-------
SECTION 5
DISCUSSION
The results of this investigation indicate that the essential amino
acid content of laying hen manure can be substantially increased with
short-term aerobic stabilization. This is of little significance, however,
unless the amino acids produced have nutritive value and can be utilized
under commercial conditions to reduce the protein content and thus the cost
of practical diets.
NUTRITIVE VALUE
The nutritive value of any feedstuff including aerobically stabilized
laying hen manure as a source of protein depends on its ability to supply
all required amino acids, particularly essential amino acids, in appropriate
amounts. Unlike freshly excreted laying hen manure, aerobically stabilized
manure appears to be a well balanced source of amino acids for laying hens
with the exception of marginal deficiencies in histidine and phenylalanine
(Table 17).
Aerobically stabilized laying hen manure also compares favorably with
soybean meal particularly as a source of methionine and appears superior to
cottonseed meal, peanut meal, and corn glutten meal as a source of essential
amino acids (Table 18). Soybean, cottonseed, peanut and corn glutten meals
are the principle plant protein sources used in the formulation of practical
diets for poultry.
Although the amino acid composition of aerobically stabilized laying
hen manure indicates that this material should be a good source of protein
for laying hens, it should be recognized that the nutritive value of this
material can only be determined by biological methods such as measurements
of protein digestibility. The physio-chemical methods used to determine
amino acid composition provide no information concerning digestibility and
release of essential amino acids in the digestive tract.
UTILIZATION
As noted in Section 1, aerobically stabilized laying hen manure has
been used successfully in feeding trials as a substitute for tap water in
the diet of White Leghorn laying hens (Martin, 1980). In that study, mixed
liquor from an undercage oxidation ditch operated as a continuous flow
reactor was circulated continuously through a trough-type watering system
43
-------
TABLE 17. COMPARISON OF THE AMINO ACID COMPOSTION OF AEROBICALLY STABILIZED AND FRESHLY
EXCRETED LAYING HEN MANURE WITH LAYING HEN AMINO ACID REQUIREMENTS.
Amino Acids
Arginine
Lysine
Histidine
Methionine
Cystine§
Tryptophan
Phenylalanine
Leucine
Isoleucine
Threonine
Valine
Laying Hen
Requirements*
1.0
0.84
0.4
0.4
0.32
0.2
0.92
1.5
1.0
0.74
0.86
Acids Supplied by 20 gm
Aerobically Stabilized
Laying Hen Manure*
1.21
1.09
0.35
0.53
#
#
0.83
1.57
1.15
1.00
1.29
Freshly Excreted
Laying Hen Manuret
0.79
0.93
0.37
0.32
#
#
0.65
1.24
1.19
0.79
0.93
* Scott £t__al.. (1976).
+ This study - 3 day continuous flow effluent (Table 16).
t This study - (Table 16).
§ Not an essential amino acid for poultry; can be synthesized from methionine.
# Not determined.
-------
TABLE 18. COMPARISON OF THE AMINO ACID COMPOSTION OF AEROBICALLY STABILIZED
LAYING HEN MANURE WITH SEVERAL PLANT PROTEIN SOURCES.
Ul
Amino Acids
Arginine
Lysine
Histidine
Methionine
Cystine§
Tryptophan
Phenylalanine
Leucine
Isoleucine
Threonine
Valine
— — Amino
Aerobically Stabilized
Laying Hen Manure, gmt
1.21
1.09
0.35
0.53
#
#
0.83
1.57
1.15
1.00
1.29
Acids Supplied
Soybean
Meal, gm*
1.4
1.3
0.48
0.30
0.33
0.26
0.96
1.48
1.08
0.76
1.08
by 20 gm of Protein
Cottonseed
Meal, gm* M
2.15
0.78
0.54
0.29
0.49
0.24
1.07
0.17
0.78
0.68
0.98
Peanut
leal, gm*
2.36
0.92
0.48
0.16
0.28
0.20
0.92
1.48
0.80
0.56
1.12
Corn Gluten
Meal, gm*
0.65
0.37
0.42
0.47
0.33
0.11
1.12
3.06
0.98
0.60
1.02
* Scott £££l_. (1976).
t This study, continuous flow reactor - 3 day time (Table 16).
§ Not an essential araino acid for poultry; can be synthesized from methionine.
# Not determined.
-------
with the overflow returned to the ditch. This utilization approach was
found to be particularly attractive due to its simplicity and adaptability
to commercial conditions. Trough-type, continuous flow watering systems are
frequently used in the poultry industry.
In more recent feeding trials conducted at Cornell University, it has
been determined that aerobically stabilized laying hen manure slurries con-
taining up to 30 gm/£ of total solids can be used as tap water substitutes
for laying hens. Although slurries containing higher concentrations are
readily consumed, these slurries are too viscous to be used with continuous
flow trough-type watering systems. Tn these recent feeding trials, it also
was established that a mature White Leghorn laying hen will consume about
300 mil/day of aerobically stabilized laying hen manure when used as a sub-
stitute for tap water. Observed values ranged from 250 m£ to 350 mZ/hen-day
varying with ambient temperatures.
Assuming that mixed liquor total solids are 20% protein (Table 16,
3 day retention time), 300 m£ of aerobically stabilized laying manure with
a total solids concentration of 30 gm/A contains 1.8 gm of protein. This
represents slightly more than 10% of a mature White Leghorn laying hen's
daily protein requirement which is 17 gm/day (Scott et al., 1976). This
would permit the use of a 16% protein in place of an 18% protein laying
ration. The calculated impact of this reduction in ration protein content
on feed costs is shown in Table 19. These figures indicate that aerobically
stabilized laying hen manure has potentially significant monetary value as a
feedstuff. For 30,000 hens, feed cost savings could exceed $10,000/year.
TABLE 19. AN ESTIMATE OF THE MONETARY VALUE OF AEROBICALLY
STABILIZED LAYING HEN MANURE AS A SOURCE OF PROTEIN
BASED ON PROJECTED FEED COST SAVINGS.
Feed Costs*
$71000 Hens/Year
$/Dozen Eggs
18% Protein Laying Rationt
plus Tap Water
16% Protein Laying Ration§
plus Aerobically Stabilized
Laying Hen Manure
Difference
$6940
6595
$ 345
$0.347
0.330
$0.017
* Assuming: 1) 95 gm of feed/hen-day 2) 1.7 kg feed/dozen eggs.
T $200.11/tonne, Agway Inc., Ithaca, NY, 1981.
§ $190.l9/tonne, Agway Inc., Ithaca, NY, 1981.
46
-------
SYSTEM DESIGN
This study has not only demonstrated that aerobic stabilization can
significantly enhance the composition of laying hen manure amino acids and
thus the potential value of this manure as a feedstuff but also has provided
a rational basis for system design. Using this information in combination
with the noted assumptions, the folowing design example for the system shown
in Figure 22 was developed. In this design example (Table 20), it was
assumed that a solids retention time of 3 days would preclude nitrification
and exertion of nitrogenous oxygen demand. Thus, the estimate for oxygen
demand was limited to carbonaceous oxygen demand using chemical oxygen
demand removed as the basis for the estimate.
The estimated cost for aeration of $5.4 x 10 /hen-day, which trans-
lates into $197/1000 hens/year, compares favorably with the previous
estimate for feed cost savings of $345/1000 hens/year (Table 20). Thus,
it appears that even when capital and other operating costs are considered,
the potential value of aerobically stabilized manure, as a feedstuff appears
adequate to justify the cost of waste stabilization and odor control.
It should be noted that it may be necessary to add an additional
process to the flow diagram shown in Figure 22. Although the absence of
nitrification is attractive in that it reduces oxygen demand and therefore
aeration costs, high residual ammonia-nitrogen concentrations (Figure 20,
3 day retention time) may be toxic to laying hens. Thus, it may be
necessary to utilize a process such as air stripping or ion exchange for
removal of ammonia nitrogen before using aerobically stabilized laying hen
manure as a tap water substitute.
SUMMARY
As indicated in the preceding discussion, the amino acid composition of
aerobically stabilized laying hen manure indicates that it should be a good
source of protein for laying hens. Estimates of the monetary value of
aerobically stabilized laying hen manure as a protein source and aeration
costs indicate that this approach for utilizing laying hen manure can be
economically feasible.
47
-------
OVERFLOW
LAYING
HENS
DILUTtON
WATER
MANURE
TAP WATER
SUBSTITUTE
AERATION
TANK
OVERFLOW
Figure 22. Process flow diagram for design example.
48
-------
TABLE 20. DESIGN EXAMPLE - A COMPLETELY MIXED, CONTINUOUS FLOW AERATION
SYSTEM FOR ENHANCING THE NUTRITIVE VALUE OF LAYING HEN MANURE.
Design Criteria and Assumptions
I. Waste Characteristics*
- Total Solids 25.1 gm/h en-day
- Chemical Oxygen Demand 20.6 gm/hen-day
2. Operating parameters
- Solids Retention Time 3 days
- Mixed Liquor Total Solids Concentration 30 gm/£
3. System Performance!
- Total Solids -Destruction 30.5%
- Chemical Oxygen Demand Removed 43.8%
4. Mixed Liquor Utilization 300 m£/hen-day
5. Oxygen Transfer Efficiency§ 1 kg 02/KwH
6. Electrical Energy Cost $0.06/KwH
Design Relationships
1. Residual total solids, gm/hen-day = (total solids produced, gm/hen-day)
x (1 - total solids destruction, decimal fraction).
2. System volume, Jl/hen = [(residual total solids, gm/hen-day) x (SRT,
days)] * (mixed liquor total solids concentration, gm/£).
3. Dilution water required, A/hen-day = (residual total solids, gm/hen-day)
* (mixed liquor total solids concentration,
4. Ultimate disposal requirements, A/hen-day = (dilution water required,
A/hen-day) - (mixed liquor utilization, A/hen-day).
5. Oxygen demand, gm 02/hen-day = (chemical oxygen demand, gm/hen-day) x
(chemical oxygen demand removed, decimal fraction).
6. Aeration cost, $/hen-day = [(oxygen demand, gm 02/hen-day) * (oxygen
transfer efficiency, gm 02/KwH)] x (electrical energy cost, $/KwH) .
Calculated Results
I. Residual Total Solids 17.4 gm/hen-day
2. System Volume 1.7 Jl/day
3. Dilution Water Required 0.6 Z/hen-day
4. Ultimate Disposal Requirements 0.3 £ /hen-day
5. Oxygen Demand 9.0 gm 02/hen-day
6. Aeration Cost $0.00054/hen-day
* Martin and Loehr, 1977.
t Figures 17 and 18.
§ Metcalf and Eddy, 1980. a = 0.85, 6 = I .0.
49
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52
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