EPA-600/2-77-204
October 1977
Environmental Protection Technology Series
POULTRY WASTE MANAGEMENT ALTERNATIVES:
A Design and Application Manual
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Athens, Georgia 30601
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-204
October 1977
POULTRY WASTE MANAGEMENT ALTERNATIVES:
A Design and Application Manual
by
J.H. Martin
R.C. Loehr
Cornell University
Ithaca, New York 14853
Grant Number R803866-01-0
Project Officer
Lee A. Mulkey
Technology Development and Applications Branch
Environmental Research Laboratory
Athens, Georgia 30605
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ATHENS, GEORGIA 30605
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DISCLAIMER
This report has been reviewed by the Environmental Research Laboratory, U.S.
Environmental Protection Agency, Athens, Georgia, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
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FOREWORD
Environmental protection efforts are increasingly directed towards
preventing adverse health and. ecological effects associated with specific
compounds of natural or human origin. As part of this Laboratory's re-
search on the occurrence, movement, transformation, impact, and control of
environmental contaminants, the Technology Development and Applications
Branch develops management or engineering tools for assessing and controlling
adverse environmental effects of agricultural practices.
To meet the increasing food needs of the nation, the agricultural in-
dustry has adopted improved production practices and increased the size of
individual farm facilities. Although clearly beneficial in increasing food
production, these large facilities have produced waste management problems
that threaten the environmental quality of the water and air. This report
describes waste management techniques to provide control of odor problems
and water pollution from egg production activities in a form that can be
used by engineers, extension personnel, and egg producers.
David W. Duttweiler
Director
Environmental Research Laboratory
Athens, Georgia
111
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ABSTRACT
Changes in the egg production industry during the past 20-30 years have pro-
duced waste management problems which threaten both water and air quality.
Results from a number of research studies have identified two processes--
aerobic, biological stabilization and drying—that provide both odor control
and the reduction of the water pollution potential of these wastes.
In this manual, the theoretical concepts underlying each poultry waste manage-
ment approach are discussed, and process design methodologies are presented.
Included are design examples to illustrate the application of design methodo-
logies. A discussion of the impact of design decisions on performance charac-
teristics and computer programs to assist in the process design for each al-
ternative are also presented.
Both high-rise, undercage drying and aeration systems are compared to identify
relative merits and provide economic projections. Odor control and plant nu-
trient conservation capabilities as well as refeeding potential for both alter-
natives are discussed.
This report was submitted in fulfillment of Grant No. R-803866-01-0 by Cornell
University under the sponsorship of the U. S. Environmental Protection Agency.
This report covers the period July 1975 to July 1977, and work was complete
as of July 1977.
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CONTENTS
Foreword
Abstract
Figures
Tables
Acknowledgements
1. Introduction
2. Raw Waste Characteristics
3. High-rise, Undercage Drying of Poultry Manure
4. Aerobic Biological Stabilization of Poultry Manure
5. Design Approaches
6. System Comparisons
Appendix
Figure A-l. High-rise, undercage drying: sensitivity
analysis of design variables - source listing
and data output
Data used for determinations of refractory and
biodegradable fractions of poultry manure
Table A-l.
Figure A-2.
Figure A-3.
Figure A-4.
Figure A-5.
Figure A-6.
Figure A-7.
Figure A-8.
Figure A-9.
Figure A-10.
Flow diagram for high-rise, undercage drying
analysis computer program
High-rise, undercage drying design analysis -
source listing
Flow diagram for high-rise, undercage drying:
simulation of system performance
High-rise, undercage drying: simulation of
system performance - source listing
Flow diagram for batch mode aeration system
process design
Batch aeration system design program - source
listing
Flow diagram for continuous flow mode aeration
system process design
Continuous flow aeration system design program
source listing
Cost of nitrogen conservation with aeration
systems for poultry wastes
v
Page
iii
iy
vi
x1
xiv
1
8
21
67
124
155
171
176
177
180
183
185
187
190
194
197
201
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FIGURES
Number Page
2.1 Effect of feed metabolizable energy content on total
solids production by laying hens. 14
2.2 Effect of metabolizable energy to protein ratio on
the quantity of total nitrogen excreted by laying hens. 15
2.3 Relationship between excretion of total solids and
moisture by laying hens. 16
3.1 Characteristics of chicken manure related to moisture
content. 22
3.2 Odor offensiveness as a function of moisture content (4). 23
3.3 Cross-section of a typical high-rise poultry house
with undercage manure drying. 27
3.4 Plan view of a typical high-rise, undercage manure
drying system showing location of drying air circulating
fans. 28
3.5 Isometric view of a high-rise poultry house. 28
3.6 Ridge and valley formation in a high-rise, undercage
manure drying system. 29
3.7 Change of partial pressure of water vapor with distance
from surface for a constant drying-rate condition
(after 11). 33
3.8 Area factor as a function of cumulative time of operation,
1971-72 (15). 39
3.9 Moisture content as a function of operation time,
1970-71 (15). 40
3.10 Moisture content as a function of operation time,
1971-72 (15). 40
vi
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FIGURES (CONTINUED)
Number Page
3.11 Manurial surface and drying air temperatures, 1970-71. 42
3.12 Manurial surface and drying air temperatures, 1971-72. 42
3.13 Change in vapor pressure differential with time of
operation. 43
3.14 Development of surface moisture content predictive
equation. 47
3.15 Redefinition of surface moisture content predictive
equation. 49
3.16. Relationship between area factor and surface moisture
content. 51
3.17 Relationship between moisture loading factor and surface
moisture content. 52
3.18 Relationship between drying air velocity and surface
moisture content. 53
3.19 Relationship between drying air velocity and surface
moisture content . 54
3.20 Cross-sectional views of the three predominate types
of cage systems for laying hens. 56
3.21 Air velocity at the airstream centerline related to
distance from fan with accumulated manure (15). 64
4.1 Diagram of the basic oxidation ditch. 69
4.2 A brush type surface aerator. 70
4.3 A cage type surface aerator. 70
4.4 Removal characteristics of total COD and suspended solids -
semi-logarithmic plot (13). 72
4.5 Graphical plot to determine the refractory fraction of a
partially biodegradable material. 83
4.6 Graphical plot to determine refractory fraction of
poultry manure total solids. 84
4.7 Graphical plot to determine refractory fraction of
poultry manure volatile solids. 84
vii
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FIGURES (CONTINUED)
Number
Page
4.8 Graphical plot to determine refractory fraction of
poultry manure COD. 85
4.9 General plot to determine refractory fraction of
poultry manure organic nitrogen. 85
4.10 Observed relationship between SRT and removal of
total solids. 87
4.11 Observed relationship between SRT and removal of
volatile solids. 87
4.12 Observed relationship between SRT and removal of COD. 88
4.13 Observed relationship between SRT and removal of
organic nitrogen. 88
4.14 Effect of effective viscosity (y ) on relative oxygen
transfer rate (a) (36). 92
4.15 Relationship between a and mixed liquor total solids
concentration in aerated poultry wastes (35). 93
4.16 Effect of MLTS concentration on a in aerated poultry
wastes (37). 94
4.17 Determination of K.a in tapwater. 107
4.18 Observed patterns of sediment accumulation in oxidation
ditches receiving poultry wastes (2). 110
4.19 Zone settling velocity versus total solids concentration
for aerated poultry wastes (51). 115
4.20 Dependence of clarifier surface area for clarification
on mixed liquor total solids concentration for aerated
poultry wastes (51). 116
4.21 Dependence of clarifier surface area for thickening on
underflow total solids concentration for aerated poultry
wastes (51). 117
5.1 Effect of type of cage system and management practices
(no. of birds/cage) on drying air velocity design
requirements. 126
vm
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FIGURES (CONTINUED)
Number Page
5.2 Relationship between quantity of moisture excreted and
design drying air velocity. 128
5.3 Relationship between initial manurial moisture content
and design drying air velocity. '29
5.4 Simulated results from a high-rise, undercage drying
performance predictive model.
5.5 Changes in carbonaceous and nitrogenous oxygen demands
in a batch aeration system for poultry wastes. '37
5.6 Comparison of rate of increase in MLTS concentration
with time as a function of system volume per bird. '38
5.7 Cumulative time of batch system operation to reach a
mixed liquor total solids concentration of 60 gm/Ji. '39
5.8 Comparison of carbonaceous oxygen demand and required
aeration capacity over the operating period for a batch
cycle. 141
5.9 The relationships between ultimate disposal and aeration
requirements in a continuously loaded, batch aeration
system for poultry wastes.
5.10 Design relationships between SRT and removal of total
and volatile solids.
145
5.11 Design relationships between SRT and removal of organic
nitrogen and COD. 145
5.12 Design relationships between SRT and carbonaceous
nitrogenous and total oxygen demands. 146
5.13 Aeration requirements as a function of MLTS concentration
in continuous flow aeration systems. 148
5.14 Ultimate disposal requirements as related to MLTS concen-
tration in a continuous flow system. 149
5.15 The relationship between ultimate disposal and aeration
requirements in a continuous flow aeration system for
poultry wastes. 150
1x
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FIGURES (CONTINUED)
Number page
5.16 Design relationships between SRT and system volume for
MLTS concentrations of 20 gm/Ł and 40 gm/Ł. 151
5.17 Design relationships between MLTS concentration and
system volume for 10 day and 30 day SRT's. 152
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TABLES
Number Page
1.1 Egg Production Flock Number and Size Changes, U.S. 2
1.2 Changes in the Egg Production Industry between 1969
and 1974 3
1.3 Total Kjeldahl Nitrogen, Percentage of Total Solids
in Animal Wastes 6
2.1 "Typical" Characteristics of Manure from Caged, White
Leghorn Laying Hens, gm/Bird-day 9
2.2 Characteristics of Manure from Caged, White Leghorn
Laying Hens, gm/Bird-day 10
2.3 Characteristics of White Leghorn, Laying Hen Manure 11
2.4 Poultry Waste Characteristics 17
2.5 Poultry Manure Characteristics Estimated in the Preceding
Design Example 19
3.1 Summary of High-Rise, Undercage Manure Drying Data for
1970-71 and 1971-72 36
3.2 Comparison of Predicted and Observed Moisture Contents
at the Beginning and End of the 1971-72 Manure Accumulation
Cycle 46
3.3 Values Used in the Simulation of High-Rise Drying 50
3.4 Ranges of Bird Density per Unit Cage Floor Area with
Different Management Practices 57
3.5 Ranges of Bird Density Based on Cage Row Width for
Triple Deck Cage Systems 57
3.6 Suggested Design Values Representative of Initial
Conditions for High-Rise Drying Process Design 59
3.7 Cross-Sectional Velocity Distribution from High-Rise
Circulating Fans 62
xi
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TABLES (CONTINUED)
Number PjKje_
4.1 Observed Removal of Total Solids, Volatile Solids,
and Chemical Oxygen Demand in Long Term Aeration
Studies 81
4.2 Refractory and Biodegradable Fractions of Poultry
Manure 86
4.3 Kinetic Coefficients for Biological Nitrification 90
4.4 Fixed Constant Values for Substrate Removal Relation-
ships for Poultry Wastes 96
4.5 Raw Waste Characteristics Used for Design Examples 97
4.6 Comparison of Process Design Computations for 30 and
60 Days of System Operation 98
4.7 Comparison of Process Design Computations for MLTS
Concentrations of 10 and 35 gm/Ł 105
4.8 Values Used to Estimate the Scour Velocity for
Poultry Manure 111
5.1 Ratios of Bird Density to Design Drying Air Velocity 127
5.2 Effects of Process Design Variables on Final Manurial
Surface and System Moisture Contents in a High-Rise,
Undercage Drying System 134
5.3 Ultimate Disposal Requirements for a Batch Aeration
System as Related to System Volume per Bird 140
5.4 Maximum Aeration Capacity and Ultimate Disposal
Requirements for a Batch System with Volume of 30 A/Bird
as Related to Cumulative Time of Operation 142
6.1 Comparison of Odor Levels and Poultry House Atmospheric
Ammonia Concentrations for Aeration and Drying Systems 155
6.2 Common Criteria for Oxidation Ditch and High-Rise
Drying Systems Design 157
6.3 Estimates of the Waste Management Component of Structural
Costs for Oxidation Ditches and High-Rise Drying 159
6.4 Annual Waste Management Facilities Costs for Oxidation
Ditches and High-Rise Drying for a 30,000 Bird Operation 160
xii
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TABLES (CONTINUED)
Number Page
6.5 Estimated Annual Fixed Costs for Oxidation Ditch
Aeration Units 161
6.6 Estimated Operating Costs for Oxidation Ditch
Aeration Units 162
6.7 Summary of Total Costs for Oxidation Ditch Aeration
Unit Oxygen Transfer 162
6.8 Comparison of Annual Fixed Manure Handling and
Disposal Equipment Costs 163
6.9 Summary of Haste Management Component Costs for
Oxidation Ditches and High-Rise, Undercage Drying 164
6.10 Comparison of Poultry Waste Management Unit Costs 165
6.11 New York State Egg Production Costs 166
6.12 Impact of Waste Management Alternatives on Egg
Production Costs 166
xiii
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ACKNOWLEDGEMENTS
The development of this design manual was supported by the U. S. Environmental
Protection Agency under Grant No. R-803866-01-0 and the College of Agriculture
and Life Sciences, Cornell University. The encouragement and guidance of
Mr. Lee A. Mulkey, U. S. Environmental Protection Agency, Athens, Georgia, who
served as the project officer, is gratefully acknowledged.
The contribution of unpublished data by Dr. A. G. Hashimoto and the advice and
comments of Mr. A. T. Sobel and Dr. D. C. Ludington are sincerely appreciated,
as is:
- The technical assistance of D. F. Sherman;
- The help of R. J. Krizek in preparation of the figures;
- The patience and skill of S. A. Giamichael in typing the
manuscript.
The development of this manual was made possible to a large degree by previous
research investigations supported by the U. S. Environmental Protection Agency;
the U. S. Department of Agriculture; the College of Agriculture and Life Sci-
ences, Cornell University; and Agway, Inc.
xiv
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CHAPTER 1
INTRODUCTION
1.1 Background and Purpose
During the past 20-30 years, the agricultural segment of the nation's economy
has undergone significant change. A shift toward a high degree of speciali-
zation and the concentration of production on fewer but larger farms has
resulted. These changes have occurred in response to the increased demand
for food due to the population expansion and to the need to maintain or
improve profitability through increased efficiency. The development and
availability of improved production practices have made these changes possible.
Nowhere have these changes been more dramatic than in the, production of
animal products. The egg production industry is a particularly noteworthy
example. In this industry, there has been a steady decline in the number of
commercial egg farms. However, the size of the remaining enterprises in
terms of numbers of laying hens has increased. Data for the years 1964 and
1969 (Table 1.1) illustrate these trends. More recent preliminary census
data (Table 1.2) indicate that these trends are continuing. Today (1977),
the minimum size of an economically viable unit is about 30,000 birds if egg
production is the only source of income. Larger operations are the rule
rather than the exception with farms containing 500,000 to 1,000,000 laying
hens not uncommon.
While these changes are clearly beneficial in terms of the availability and
cost of food, they have produced waste management problems which threaten the
quality of the environment. The trend toward fewer but larger poultry farms
has produced larger quantities of these wastes at specific sites increasing
the potential for pollution of surface and ground waters. In addition, the
adoption of high density, confinement production techniques has resulted in
wastes creating serious odor problems.
In the egg production industry, the trend toward intensification has been
accompanied by specialization. In the past, many farms combined egg produc-
tion with other enterprises such as grain production. Today many farms,
especially the larger operations, purchase some or all of the required feed-
stuffs. Therefore land for crop production may not be part of the egg pro-
duction enterprise and opportunities for waste disposal may be limited.
Clearly, a balance between food production and environmental quality is needed,
A return to former production practices can not meet current demands for food
and still maintain the present high standard of living. However, adoption of
1
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TABLE 1.1. EGG PRODUCTION FLOCK NUMBER
AND SIZE CHANGES, U.S. (1)
1964
Chickens on hand, 4 months old and over
Under TOO
TOO - 3,199
3,200 - 9,999
10,000 and over
Number of
farms (1,000)
896.2
300.9
12.9
5.8
Percent of
farms
73.7
24.7
1.1
0.5
Percent of
birds
7.3
30.7
21.0
41.0
1969
Chickens on hand, 3 months old and over
Number of
farms (1,000)
337.7
115.1
9.2
8.9
Percent of
farms
71.7
24.4
2.0
1.9
Percent of
birds
2.7
10.8
14.9
71.6
1,215.8
100.0
100.0
470.9
100.0
100.0
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TABLE 1 2. CHANGES IN THE EGG PRODUCTION INDUSTRY
BETWEEN 1969 AND 1974 (2)
Farms With Sales Exceeding $2500
1974 1969
Number of Farms
Number of Birds*
196,764
277,003,509
280,007
290,900,729
*Hens and pullets of laying age, 3 months or older.
low standards of environmental quality also is unacceptable. The solution
is the development of new animal waste management techniques which will pro-
tect the environment and simultaneously maintain or increase levels of both
production and efficiency.
During the past several years, the development of new techniques for the
management of the manure resulting from intensive egg production activities
has been the objective of a number of research studies. The result has been
the identification of two processes—aerobic, biological stabilization and
drying—that provide both odor control and the reduction of the water pollu-
tion potential of these wastes. Both processes have been examined in labora-
tory, pilot plant, and full-scale studies. The results of these studies have
identified feasible design and operating modes, as well as have provided a
basis for estimation of capital and operating costs.
The objective of this manual is to assemble and translate this information
into a form that can be used by engineers, extension personnel, and egg
producers to:
1. Understand the relative merits of aeration and drying systems for
the management of poultry wastes.
2. Design such systems to achieve a desired quality of liquid or dry
end-product and to accomplish odor control, waste stabilization,
and nitrogen control as necessary.
1.2 Scope of the Manual
The contents of this manual include:
1. A discussion of production rates and the physical and chemical
characteristics of poultry manure including variability and its
causes.
2. A discussion of the theoretical concepts involved in both the
aerobic stabilization and drying approaches to poultry waste
management.
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3. Presentation of process and physical design information as well
as design examples for each system.
4. A discussion of the relative merits of each system along with
economic projections to provide a basis for system selection for
specific situations.
1.3 Historical Background
Before proceeding, it appears useful to briefly examine the developments in
the egg industry which have created the present problems of waste management.
Perhaps the most important factor in the development of commercial egg pro-
duction as it exists today was the change from the floor to the cage manage-
ment system. As the name implies, the floor system consisted of hens
unconstrained on the floor of pens. Sawdust, straw or some similar material
was placed on the pen floor, and the accumulated manure mixed with this
material. The result, termed litter, provided a medium for stabilization
through drying and a degree of biological activity. It also provided a
storage mechanism for periods of up to 12 months which represents a normal
laying cycle.
The floor or litter system had two disadvantages which resulted in the con-
version to the cage management system. One, the cage system allowed an
increase in bird density which lowered housing costs per hen. The minimum
floor area per bird in a floor system was about 0.19 square meters (2 square
feet). At higher densities, the litter could not be kept dry and dirty eggs
and diseese problems resulted. Conversion to the cage system reduced floor
area per bird to about 0.04 square meters (0.45 square feet).
The secord disadvantage of the floor system was its high labor requirements.
Although mechanical feeders were first used with floor systems, egg collection
and manure handling remained manual tasks. With a floor system, one man could
care for f,000 to 10,000 birds. Today, with cages, one man can handle from
35,000 to 50,000 hens.
The adoption of new management techniques resulted in changes in both physical
waste characteristics and the nature of poultry farms. With the increase in
bird density, the natural drying and stabilization which was characteristic
of the floor system no longer occurred. The raw waste, which has a moisture
content of about 75 percent on an as excreted wet basis, was collected in .pits
constructed below the cages. In the "as produced" form, these wastes were
difficult to handle since they were not amenable to either conventional liquid
or solid handling techniques. Due to the semi-solid nature of the waste, the
transition to liquid handling systems occurred. Additional water was normally
added directly or via water spillage to create a pumpable slurry. Liquid
manure systems were attractive because the physical labor associated with
manure handling was reduced.
The shift to handling poultry manure in either a semi-solid or liquid form
created an ideal environment for uncontrolled, anaerobic microbial activity.
Such activity results in objectionable odors which are exhausted through
ventilation fans and are dispersed when the wastes are disposed of on the land.
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The odors consist of malodorous mercaptans, amines, volatile acids, and
sulfides. In addition to malodors, these forms of poultry manure provided
an attractive breeding site for vermin, particularly the common house fly,
Musca domestica. These problems were intensified by suburban encroachment
into agricultural areas. Odor problems related to poultry farms have resulted
in legal or administrative actions by a number of state environmental agencies.
Concurrent with the shift to the cage system was the beginning of the trend
toward fewer but larger poultry farms as discussed previously. As flock
size increased, many farms reduced or eliminated cropping activities and pur-
chased some or all the feed required. Therefore, land for the production of
feed is not necessarily a requirement for egg production. In many instances
the purchase of feed may present economic advantages. The combination of
large populations and limited land resources can result in heavy waste loadings
on small areas. This intensifies the potential for water pollution. A not
untypical examples would be a 250,000 bird farm with only 16.2 hectares
(40 acres) of land available for waste disposal.
1.4 Water Pollution Potential
Odor represents the most perceptible pollution problem associated with poultry
manure. However, these wastes also possess a significant water pollution
potential due to the presence of nutrients and oxygen demanding materials.
Wastes that are discharged to surface waters require high levels of removal of
both oxygen demanding and nutrient compounds. In contrast, the effluent guide-
lines for the feedlot industry (3) state that animal wastes should not be dis-
charged to watercourses. This is in keeping with the historic practice of
returning animal manures to the land. The use of the land for ultimate disposal
is an important factor in identifying ultimate waste management objectives.
In light of the waste stabilization capacity of soils, emphasis in animal
waste management should be directed towards preventing the movement of
oxygen demanding and nutrient fractions into surface and ground waters. This
can be achieved in some instances by management strategies limiting ultimate
disposal to situations conducive to nutrient uptake by crops and least
susceptible to surface runoff events. Where biological waste stabilization
is desired, emphasis should be on the removal of the oxygen demanding and
nutrient fractions which are susceptible to movement to surface and ground
waters. This level of stabilization also can provide effective odor control.
Two important water pollution characteristics of poultry manure are the soluble
organic fraction and the nitrogen content. The soluble carbonaceous fraction
of poultry manure is significant. As much as 24 percent of the chemical oxygen
demand (COD) can be soluble (4). Storage under uncontrolled anaerobic con-
ditions will increase the soluble organic fraction.
Poultry excreta contains the highest concentration of nitrogen (Table 1.3)
of the major agricultural species of domestic animals. Of particular concern
is the loss of nitrogen to both surface and ground waters where land resources
for waste disposal are limited. Numerous studies (8, 9, 10) have shown that
nitrogen is the limiting parameter in the disposal of animal wastes to the
land. Application rates should be limited to crop production requirements.
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Thus, poultry waste management approaches should be geared to using such
application rates. Where land area is limited, these approaches may need to
include appropriate nitrogen control methods.
TABLE 1.3. TOTAL KJELDAHL NITROGN, PERCENTAGE OF
TOTAL SOLIDS IN ANIMAL WASTES
TKN, % of TS
Beef
1.9 (5)*
Dairy
4.9 (6)
Swine
3.4 (7)
Laying Hens
7.8 (4)
*Numbers in parentheses indicate data source.
1.5 References
1. Jasper, A.W. Some Statistical Highlights of the Poultry Industry.
American Farm Bureau Federation. 1973.
2. U.S. Department of Commerce, Bureau of the Census. 1974 Census of Agri-
culture, Preliminary Report. Washington, D.C. December 1976.
3. Federal Register. Effluent Guidelines Standards, Feedlots Point Source
Category. Washington, D.C. 39:5704-5708. February 1974.
4. Martin, J.H. and R.C. Loehr. Demonstration of Aeration Systems for
Poultry Wastes. Environmental Protection Technology Series Report No.
EPA-600/2-76-186, U.S. Environmental Protection Agency, Washington, D.C.
1976. 151 p.
5. Development Document for Effluent Guidelines and New Performance Standards,
Feedlots Point Source Category. Environmental Protection Technology
Series Report No. EPA-440/1-74-004-A, U.S. Environmental Protection Agency,
Washington, D.C. 1974. 318 p.
6. Morris, G.R. Anaerobic Fermentation of Animal Wastes: A Kinetic and
Empirical Design Evaluation. Unpublished M.S. Thesis. Cornell University,
Ithaca, New York. 1976. 193 p.
7. Converse, J.C., D.L. Day, J.T. Pfeffer, and B.A. Jones, Jr. Aeration
with ORP Control to Suppress Odors Emitted from Liquid Swine Manure
Systems. In: Livestock Waste Management and Pollution Abatement. ASAE.
St. Joseph, Michigan. 1971. p. 267-271.
8. Rutgers University, College of Agriculture and Environmental Science.
Poultry Manure Disposal by Plow-Furrow-Cover. Environmental Protection
Technology Series Report No. EPA-670/2-73-085. U.S. Environmental
Protection Agency, Washington, D.C. 1974. 108 p.
6
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9. Bartlett, H.O. and L.F. Marriot. Subsurface Disposal of Liquid Manure.
In: Livestock Waste Management and Pollution Abatement. ASAE.
St. Joseph, Michigan. 1971. p. 258-260.
10. Loehr, R.C., T.B.S. Prakasam, E.G. Srinath, T.W. Scott and T.W. Bateman,
Design Parameters for Animal Waste Treatment Systems - Nitrogen Control.
Environmental Protection Technology Series Report No. EPA-600/2-76-190.
U.S. Environmental Protection Agency, Washington, D.C. 1976. 144 p.
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CHAPTER 2
RAW WASTE CHARACTERISTICS
2.1 Introduction
Knowledge of the physical and/or chemical characteristics of poultry manure
is necessary for the design of both aerobic biological stabilization systems
and drying systems. Information defining "typical" characteristics of the
wastes from caged, White Leghorn laying hens is available from several sources
(1, 2, 3, 4). These values (Table 2.1) represent averages of data presented
by several investigators. For example, characteristics presented by the U.S.
Environmental Protection Agency (USEPA) (1) and Jones, et al. (3) were
originally reported by Miner (5) and were developed from data of Dornbush and
Anderson (6), Hart and Turner (7), and Taiganides. Comparison of these values
(Table 2.1) with other available data indicates that considerable variation
exists. Therefore, the suitability of "typical" or average values that can be
used for design purposes is questionable. Use of such values could result in
either under or over-design with the possible result of excessive operating
costs or process failure.
While on-site sampling is the best approach to determine waste characteristics,
this practice may not be possible for the design of new facilities. There-
fore an understanding of the causes of variation of waste characteristics and
of a method to estimate actual waste characteristics is necessary for effective
design of poultry waste management systems.
The objectives of this chapter are to present:
1. A review of reported poultry manure characteristics.
2. A discussion and analysis of the factors which may be responsible
for the observed variations.
3. The development of an approach to estimate waste characteristics
when sampling and analysis is not possible.
2.2 Reported Poultry Manure Characteristics
The characteristics of manure from various genetic strains of the White Leg-
horn hen have been reported by several investigators. A summary of reported
values is presented in Table 2.2. The values presented are reported data
only from studies where a 24 hour manure collection period was used with
analysis immediately following the collection period. Only such data were
-------
included because the 24 hour collection period integrates possible variation
in manure production rate throughout the day.
TABLE 2.1. "TYPICAL" CHARACTERISTICS OF MANURE FROM CAGED,
WHITE LEGHORN LAYING HENS, GM/BIRD-DAY
Reference
(1)
(2)
(3)
(4)
Wet Solids
120.5
108.3
120.5
127.4
Moisture
102.3
81.0
102.3
95.6-101.4
TS* VS*
35.5 26.4
27.4 19.2
35.5 26.4
25.5-31.8
TN*
23.5
1.5
4.1
0.5-2.0
COD*
32.1
24.5
32.1
-
*TS =
VS =
TN =
COD =
Total Solids
Volatile Solids
Total Nitrogen
Chemical Oxygen
Demand
As shown in Table 2.2, significant differences exist for each parameter. Com-
parison of "typical" values for each parameter presented in Table 2.1 and the
range of values in Table 2.2 shows that while the typical values generally
fall within the range for each parameter, the range for each parameter is
quite large. Therefore, neither the typical values nor data from any study
reported in the literature can be used with confidence for design purposes.
It should be noted that the value of total nitrogen (TN), 23 gm/bird-day,
presented by USEPA (1) appears to be a mistake. Miner (5) reported TN pro-
duction as 11.5 percent of total solids. USEPA (1) reported TN as 0.0115
kilograms per kilogram of liveweight per day or 66 percent of total solids.
2.3 Potential Factors Affecting Manure Characteristics
There are several factors which may be responsible for the variation in the
characteristics of poultry manure. These include stage of the laying cycle,
genetic strain, and characteristics of the diet. The following discusses
these various factors.
The laying cycle can be divided into three phases (13). During Phase I, body
weight increases from 1450 to 1900 grams and egg production increases from
zero to 85 percent. Egg production declines to 65 percent during Phase II,
and is less than 65 percent during Phase III. There is a relationship between
the three phases of egg production, feed consumption, and manure production.
In a study of manure characteristics during the three phases of the laying
cycle, Hashimoto (14) reported that variations in the ratios of wet solids,
total solids, volatile solids, and total nitrogen production to total solids
production were generally less than one standard deviation from the yearly
-------
TABLE 2.2. CHARACTERISTICS OF MANURE FROM CAGED,
WHITE LEGHORN LAYING HENS, GM/BIRD-DAY
o
Reference
(6)
(7)
(8)
(9)
(10)
(ID
(12)
- Range
Strain
Honegger
-
Shaver
Hyline
Babcock
H & N**
Hubbards
Babcock
H & N**
Babcock
of values
Wet Solids
106.1
63.7
108.4
96.7
145.4
140.4
145.4
148.3
-
127.1
189.7
63.7-189.7
Moisture
77.3
33.7
78.8
67.7
110.4
103.5
109.5
111.8
-
98.6
141.5
33.7-141.5
TS*
28.8
30.0
29.6
29.0
35.0
36.9
35.9
36.5
37.2
28.5
48.2
28.5-48.2
VS*
20.2
23.2
22.1
20.6
25.6
27.1
26.9
26.8
27.6
21.1
32.6
20.2-32.6
TN*
1.4
1.6
2.3
2.2
2.4
2.4
2.5
2.5
3.1
1.8
2.8
1.4-3.1
COD*
23.0
25.8
19.2
21.4
-
28.9
18.9
36.4
18.9-36.4
Date of
Study
1964
1965
1,973-74
1974-75
1974
1972-73
1969-71
1970
* TS Total Solids
VS = Volatile Solids
TN = Total Nitrogen
COD = Chemical Oxygen Demand
** Heistoff and Nelson
-------
average. Yearly averages and standard deviations for three flocks of birds
studied by Hashimoto are presented in Table 2.3. In light of the data pre-
sented by Hashimoto (14), it appears that possible differences in the stage
of laying cycle are not responsible for the wide variation in reported waste
characteristics (Table 2.2). Moreover, it appears that yearly averages are
acceptable for design purposes.
TABLE 2.3. CHARACTERISTICS OF WHITE LEGHORN,
LAYING HEN MANURE (14)
Production (gm/bird-day) +_ 1 Standard Deviation
Flock 1 Flock 2 Flock 3
n = 80 n = 52 n=9
Wet Solids
Moisture
Total Solids
99 + 23
73 + 23
26 + 4
99 +_ 17
74 + 17
25 + 5
111 + 5
87 + 5
24 + 2
Total Nitrogen
Chemical Oxygen Demand
Percent of Total Solids +_ 1 Standard Deviation
8 + 2 8 +_ 1 8 + 1
56+29 62+15 58+4
Little is known concerning the relationship between genetic strain and manure
characteristics. However, data (9) from a study involving four different
strains of White Leghorn hens housed in the same environment and receiving
the same diet indicated no significant difference in waste characteristics as
related to genetic strain (Table 2.2). However, the results of three separate
studies (9, 10, 12) involving the Babcock strain show considerable variation.
Therefore, while it appears that genetic strain is not a significant factor
concerning the characteristics of wastes from White Leghorn hens, this conclu-
sion may apply only to the different genetic strains of the White Leghorn
breed. It may not be applicable when considering other breeds such as the
Rhode Island Red.
Consideration of the third factor, diet, requires an understanding of some of
the basic concepts of poultry nutrition. Although taste has a large influence
on the amount of food consumed by man and certain other mammals, it appears to
be of minor importance in feed consumption by poultry (13). The energy
requirement seems to be the primary factor governing feed consumption by the
chicken. The laying hen can adjust her feed consumption of diets containing
from 2500 to 3300 kilocalories of metabolizable energy (ME) per kilogram of
feed (1135 - 1500 kcal per Ib) to obtain adequate energy. The hen will
11
-------
increase feed consumption until adequate metabolizable energy is obtained.
With feeds containing low levels of ME, a greater quantity of feed will be
consumed as compared to feeds with greater ME content. Therefore, feed con-
sumption will increase as the metabolizable energy of the diet decreases and
an increase in the quantity of total solids (TS) excreted should occur.
Energy requirements for the laying hen are not constant. They vary slightly
with the phase of the laying cycle and more significantly with climate. The
daily energy requirement for the White Leghorn hen varies from 310 kcal ME/day
in cooler climates to 265 kcal ME/day in warmer regions (13). However, lower
energy feeds are commonly used in warmer regions somewhat offsetting lower
feed consumption due to lower ME requirements.
Although the laying hen has specific protein requirements to maintain optimum
productivity, intake of protein is governed by the relationship between
protein and metabolizable energy in the diet. Daily dietary protein require-
ments for the three phases of egg production are 18, 16, and 15 grams of
protein/hen-day (13). Since feed consumption is increased when ME is decreased
and vice-versa, it is necessary to adjust the protein content of the diet to
establish proper protein intake. This relationship is known as the ratio of
metabolizable energy to protein percentage (ME/P) which has units kcal/kg/%.
It is determined by dividing the kcal ME/kg of feed by the percentage of
dietary protein. Values of ME/P to provide minimum protein requirements in
cool climates are 166-170, 193-195, and 196-200 respectively for the three
phases of egg production (13). For warm climates, a 10 percent reduction is
suggested. As the ME/P ratio decreases from the minimum requirements thereby
increasing protein intake, increase in the quantity of nitrogenous compounds
excreted should occur.
Water consumption, like nitrogen intake, is principally a function of feed
intake within the environmental temperature range of 14°C to 26°C (58-78°F)
(13). With a diet containing approximately 10 percent moisture, water consump-
tion under normal conditions may range from 1.5 to 2.0 grams of water/gram
of feed consumed. Medway and Kare (15) found that water lost via respiration
amounted to 53 grams/day for hens at 32 weeks of age. Water required/egg
produced was reported to be approximately 35 grams. This suggests that the
metabolic water requirements are relatively constant and increased water con-
sumption due to increased feed intake should increase the quantity of moisture
excreted.
To date (1977), only limited discussion of the relationship of feed to
poultry waste characteristics has been published. In a study examining the
practice of refeeding dehydrated poultry manure, Nesheim (16) observed an
inverse relationship between fecal dry matter (total solids) as a percentage
of feed consumed and as the quantity/hen-day and the metabolizable energy
level of the diet. Data presented by Hashimoto (14) also showed the same
inverse relationship between total solids excreted and metabolizable energy
content of the feed. Of the several possible reasons for the observed varia-
tions in the characteristics of poultry wastes, the effect of differences in
diet appears to be the most logical and fundamental. The observed relation-
ships between the total solids excreted and the metabolizable energy content
of the diet is discussed in detail in the following section.
12
-------
2.4 Relationships Between Feed and Waste Characteristics
Based upon the above nutritional concepts, it was hypothesized that definitive
relationships exist between feed and manure characteristics. Since informa-
tion concerning feed characteristics in conjunction with waste characteristics
is limited, it was only possible to examine three specific relationships.
They are total solids production as a function of diet ME content, total
nitrogen excreted versus the ME/P ratio, and the relationship between the
quantity of moisture and total solids excreted. The last item represents an
indirect method to examine the relationship between feed consumption and water
excretion. This approach was necessary due to the lack of appropriate data.
To test the hypothesis that manurial total solids production is a function of
the ME content of the feed, data presented by Hashimoto (14) and Nesheim (16)
as well as other unpublished data (9, 17) were analyzed and are presented in
Figure 2.1. Linear regression analysis using the least squares method was
used to fit a straight line to the data. The regression coefficient of 0.97
indicates that a linear relationship exists between the two variables over the
range of values analyzed. The mathematical relationship was:
Total solids excreted, gm/bird-day =
- .038 (feed ME content, kcal/kg) + 138 (2.1)
for feed ME values between 2445 and 3018 kcal per kg. This relationship
suggests that not only can manurial total solids production be calculated from
feed ME content, but also that use of higher energy feeds will reduce manurial
total solids production.
The second relationship examined was that between the ME/P ratio of the feed
and the quantity of nitrogen excreted/day. The available data (8, 9, 18) are
presented in Figure 2.2. Again, linear regression analysis was used to fit a
straight line to the data and to determine the mathematical relationship
between the data. This relationship was:
Total nitrogen excreted, gm/bird-day =
- .018 (ME/P ratio of the feed) + 5.09 (2.2)
for ME/P ratios between 151.5 and 177.5. This relationship shows that as pro-
tein intake increases within the range of values analyzed, the quantity of
nitrogen excreted will also increase.
The third relationship analyzed was that between the quantity of moisture and
total solids excreted/bird-day. The data presented in Table 2.2 was used as
the basis for this analysis. As noted, this approach represents an indirect
method of examining the relationship between the consumption of water in rela-
tion to feed intake and moisture excreted. The data used and the results of
the linear regression analysis are presented in Figure 2,3. The mathematical
relationship between the two variables is:
13
-------
48
44
40
o
•o
i
^ 36
E
CO
Ł 32
O
CO
_i
I- 28
24
20
• HASHIMOTO (14)
• NESHEIM (16)
A HASHIMOTO (17)
* HASHIMOTO (9)
Y= -.038X
R=.97
139
I
2200 2400 2600 2800 3000 3200
FEED METABOLIZABLE ENERGY CONTENT, kcal/kg
Figure 2.1. Effect of feed metabolizable energy content on total
solids production by laying hens.
14
-------
LJ
2.4
2.2
2.0
§ 1.8
1.6
1.4
Y=-.OI8X-I-5.09
R= 0.76
HASHIMOTO (14)
HASHIMOTO (9)
HASHIMOTO (18)
150 155 160 165 170 175
METABOLIZABLE ENERGY TO PROTEIN RATIO, (ME/P)
Figure 2.2. Effect of metabolizable energy to protein ratio on the
quantity of total nitrogen excreted by laying hens.
180
15
-------
150
>s
O
130
C/> 110
E
en
Q*
LJ
Ł90
O
X
LU
o
xc
70
50
Y= 3.59X-26.4
R= 0.80
20 30 40 50
T.S. EXCRETED, gms/bird-day
60
Figure 2.3. Relationship between excretion of total solids and moisture
by laying hens.
16
-------
gm f-LO excreted/bird-day =
3,59'(gm total solids excreted/bird-day) - 26.4 (2.3)
for total solids values between 28.2 and 48.2 gm /bird-day. This relation-
ship indicates that when lower feed ME content results in increased feed con-
sumption, the quantity of moisture as well as total solids excreted increases.
While it is clear that feed characteristics should also effect other parameters
such as volatile solids (VS), fixed solids (FS), and chemical oxygen demand
(COD), sufficient information was not available to develop similar relation-
ships for these parameters. In order to provide some basis to estimate values
for these parameters for desiqn, data presented in Table 2.2 was used to
establish ranges of expected values. These values (Table 2.4) are presented
as a percentage of total solids to enable use with the foregoing information.
TABLE 2.4. POULTRY HASTE CHARACTERISTICS
Parameter Percent of Total Solids
Volatile Solids - 67-77%
Fixed Solids - 23-33%
Chemical Oxygen Demand - 65-86%
2.5 Design Example
This example of the use of the above information determines the waste
quantities that can be used for the design of a 30,000 bird waste manage-
ment system. The birds will be White Leghorn hens. The feed for the hens
is assumed to be a 16 percent protein laying ration containing 2800 kcal
of metabolizable energy (ME) per kq of feed. The procedures to determine the
quantities of total solids, total nitrogen, and water excreted per bird-day
and for the specified number of birds are as follows:
A. Total solids - Using Equation 2.1, the quantity of total solids
excreted/bird-day is:
-.038 (2800 kcal/kg of feed) + 139 -
32.6 gm total solids/bird-day
or 978 kg/day for 30,000 birds.
B. Total nitrogen - The metabolizable energy to protein ratio (ME/P)
for the feed is:
17
-------
ME _ 2800 kcal/kg _ ,
P~ " ~ " l
Using Equation 2.2, the quantity of nitrogen excreted/bird-day is:
-.018 (175, ME/P ratio) + 5.09 =
1.94 gm total nitrogen/bird-day
or 58.2 kg/day for 30,000 birds.
C. Moisture - From A, total solids production was calculated to be
32.6 gm/bird-day. Using Equation 2.3, the quantity of moisture
excreted/bird-day is:
3.59 (32.6 mg total solids excreted/bird-day) - 26.4 =
90.6 gm H20/bird-day
or 2718 kg/day for 30,000 birds.
Values/bird-day for these three parameters also may be determined directly
from Figures 2.1, 2.2, and 2.3. When necessary, values for volatile solids
(VS), fixed solids (FS), and chemical oxygen demand (COD) can be estimated
from calculated values for total solids and percentages presented in Table
2.4. It is recommended that conservative values of 77 and 86 percent for
volatile solids and COD be used. The values for VS, FS, and COD can be
determined as follows:
D. Volatile solids - From A, total solids production was calculated
to be 32.6 gm/bird-day. Using the value of 77 percent, the quantity
of volatile solids excreted/bird-day is:
32.6 gm total solids/bird-day x .77 =
25.1 gm volatile solids/bird-day
or 753 kg/day for 30,000 birds.
E. Chemical oxygen demand (COD) - Using the values of 32.6 gm of total
solids/bird-day and 86 percent for COD, the quantity of COD excreted/
bird-day is:
32.6 gm total solids/bird-day x .86 =
28.0 gm COD/ bird-day
or 841 kg/day for 30,000 birds.
F. Fixed solids - Using the previously determined values for total
solids and volatile solids, the quantity of fixed solids excreted/
bird-day is:
18
-------
32.6 gm total solids/bird-day - 25.1 gm
volatile solids/bird-day =
7.4 gm fixed sol ids/bird-day
The poultry manure characteristics estimated in the preceding design example
are summarized in Table 2.5.
TABLE 2.5. POULTRY MANURE CHARACTERISTICS ESTIMATED IN
THE PRECEDING DESIGN EXAMPLE
Parameter
Total Solids
Total Nitrogen
Moisture
Volatile Solids
Chemical Oxygen Demand
Fixed Solids
gm /bird-day
32.0
1.94
90.6
25.1
28.0
7.4
For 30,000 birds
kg /day
978
58.2
2718
753
841
222
Thus, it is possible to estimate the manure characteristics and quantities
using the relationships identified in this chapter. This information is
valuable in considering manure management alternatives and will be used in
the manure management design examples presented in later chapters.
2.6 References
1. Development Document for Effluent Guidelines and New Performance
Standards, Feedlots Point Source Category. Environmental Protection
Technology Series Report No. EPA -440/1-74-004-a. U.S. Environmental
Protection Agency, Washington, D.C. 1974. 318 p.
2. Miner, J.R. and R.J. Smith (ed). Livestock Waste Management with
Pollution Control. North Central Regional Publication 222. Midwest
Plan Service, Iowa State University. Ames, Iowa. 1975. 89 p.
3. Jones, D.D., D.L. Day, and A.C. Dale. Aerobic Treatment of Livestock
Wastes. Bulletin 737, University of Illinois at Urbana-Champaign.
1970. 55 p.
19
-------
4. Canada Department of Agriculture. Canada Animal Waste Management Guide.
Publication 1543. Ottawa, Ontario. 1974.
5. Miner, R.J. (ed). Farm Animal-Waste Management. North-Central Regional
Research Publication 206. Iowa Agr. Exp. Sta. Special Report 67. Ames,
Iowa. 1971. 44 p.
6. Dornbush, J.N. and J.R. Anderson. Lagooning of Livestock Wastes in
South Dakota. Proc. 19th Industrial Waste Conf., Purdue University,
Lafayette, Indiana. 1965. p. 317-325.
7. Hart, S.A. and M.E. Turner. Lagoons for Livestock Wastes. J. Water
Poll. Control Fed. 37:1578-1596. 1965.
8. Martin, J.H. and R.C. Loehr. Demonstration of Aeration Systems for
Poultry Wastes. Environmental Protection Technology Series Report No.
EPA-600/2-76-186. U.S. Environmental Protection Agency, Washington, D.C.
1976. 151 p.
9. Hashimoto, A.6. Unpublished data. Cooperative Investigation of ARS-
USDA and Cornell University. Ithaca, New York. 1974.
10. Martin, J.H. and R.C. Loehr. Aerobic Treatment of Poultry Wastes. J.
Agric. Eng. Res. 21:157-167. 1976.
11. Stewart, T.A. and R. Mcllwain. Aerobic Storage of Poultry Manure. In:
Livestock Waste Management and Pollution Abatement. ASAE. St. Joseph,
Miciigan. 1971. p/261-262.
12. Dugan, G.L., C.G. Golueke, W.J. Oswald, and C.E. Rixford. Photosynthetic
Reclamation of Agricultural Solid and Liquid Wastes. SERL Report No.
70-1, University of California, Berkley. 1970. 165 p.
13. Scott, M.L., M. Nesheim, and R.J. Young. Nutrition of the Chicken.
M.L. Scott and Associates, Ithaca, New York. 196^. 511 p.
14. Hashimoto, A.G. Characterization of White Leghorn Manure. Proc. Agric.
Waste Management Conf., Cornell University, Ithaca, New York. 1974.
p. 141-152.
15. Medway, W. and M.R. Kare. Water Metabolism of the Growing Domestic
Fowl with Special Reference to Water Balance. Poultry Science 38:631-
639. 1959.
16. Nesheim, M.C. Evaluation of Dehydrated Poultry Manure as a Potential
Poultry Feed Ingredient. Proc. Aqric. Waste Management Conf., Cornell
University, Ithaca, New York. 1972. p. 301-309.
17. Hashimoto, A.G. Unpublished data. Cooperative investigation of ARS-
USDA and Cornell University. Ithaca, New York. 1975.
18. Hashimoto, A.G. Unpublished data. Cooperative investigation of ARS-
USDA and Cornell University. Ithaca, New York. 1976.
20
-------
CHAPTER 3
HIGH-RISE, UNDERCAGE DRYING OF POULTRY MANURE
3.1 Introduction
Research (1, 2, 3) has shown that the drying of poultry manure can be an
effective waste management technique. The removal of water from such manure
provides the following advantages:
A. Improvement in handling characteristics;
B. Reduction in weight and volume;
C. Reduction in offensive odor.
With the removal of moisture, poultry manure loses its adhesive qualities
becoming granular in nature. In this state, it can be handled as a solid
using equipment such as elevators, augers, and front-end loaders. The rela-
tionship between moisture content and handling characteristics for poultry
manure is presented in Figure 3.1. In addition to the reduction in weight,
a decrease in volume also occurs. Reduction in moisture content to equili-
brium levels results in a volume reduction of 40 to 50 percent (5). One of
the important benefits of drying is the odor control which results from
moisture removal (Figure 3.2).
Although drying and biological treatment processes have the common objective
of odor control, they differ in other areas. While biological treatment uses
microbial activity to achieve waste stabilization through the conversion of
carbonaceous compounds to carbon dioxide and water, the removal of water
limits microbial activity in drying systems. This is consistent with the
objective of odor control by minimizing the production of odorous compounds
characteristic of uncontrolled anaerobic processes. Some waste stabilization
can occur by microbial and/or physical mechanisms during the drying process.
While it can not be documented that drying poultry manure reduces the water
pollution potential of these wastes via stabilization, it can be considered a
management approach for water pollution control. Effective poultry manure
drying permits the long term storage of these wastes without odor problems
during storage or upon ultimate disposal to the land. This provides manage-
ment flexibility to permit scheduling of ultimate disposal in a manner that
will limit uncontrolled losses of contaminants to the environment.
Numerous approaches to the problem of removing moisture from poultry wastes
have been investigated. Included are physical/chemical and evaporative
21
-------
0
10
20
o
UJ
O 30
2E
iu
"40
50
to
O
60
2 70
u
QC
o! 80
100
80
ODOR, AMMONIA, MOLD WITH TIME
CO
"STICKY"
- DIFFICULT
TO HANDLE
CAN BE HANDLED AS
A GRANULAR SOLID
70
60 50 40 30 20
MOISTURE CONTENT, PERCENT WET BASIS
10
Figure 3.1. Characteristics of chicken manure related to moisture content (4).
-------
co
co
LJ
Z
LJ
>
co
z
LJ
ro
co
CC
O
O
O
5 VERY STRONG OFFENSIVE ODOR
4 STRONG
3 DEFINITE
2 FAINT
I VERY FAINT
0 NO OFFENSIVE ODOR
0
I
I
60 50 40 30 20 10
MOISTURE CONTENT, PERCENT WET BASIS
Figure 3.2. Odor offensiveness as a function of moisture content (5).
-------
techniques. A study by Cassell (6) examined the use of a vacuum filter, a
centrifuge and a hydraulic press for the dewatering of raw poultry wastes.
Both the vacuum filter and the centrifuge required chemical conditioning and
produced a cake with a total solids content of 20 to 25 percent. The most
promising approach was the hydraulic press which produced a cake with a total
solids content of 45 to 55 percent without chemical conditioning. However,
all three approaches produced liquid effluent having a high in chemical oxygen
demand (COD). Subsequent adoption of these techniques by the poultry industry
did not occur.
Drying systems for poultry manure using both heated and unheated air have been
developed and evaluated. Commonly, the input of heat energy is associated
with industrial type manure driers such as rotary drum units. Unheated air
normally is used with undercage drying systems.
The use of industrial type driers for the removal of moisture from poultry
manure has been examined by several investigators. Ludington (7) pre-
sented a cost analysis of dehydration, pelleting, and bagging of poultry
manure using a rotary drum drier. For a plant operating 24 hours per day
and an initial manure moisture content of 76 percent, the processing cost
was $34 per ton of dried manure. The cost for dehydration alone was $25.50
per ton. At a selling price of $20 per ton of pelleted manure, the cost
of manure dehydration was estimated to be $0.17 per bird per year. These
calculations were based on 1963 prices for energy and equipment. The
present (1976) selling price of dried manure would have to be significantly
higher to recover a comparable fraction of operating costs due to the
increased energy and equipment costs.
Surbrook, et al. (2) presented a more favorable economic analysis of dehydra-
tion using a drier developed at Michigan State University. They estimated
total costs to be $31.44 per dry ton in 1971. Assuming increases only in
energy costs to $0.12 per liter ($0.45 per gallon) for No. 2 fuel oil and
$0.035 per kilowatt-hour for electricity, present costs are estimated to be
$49.98 per dry ton. It should be noted that neither figure includes equipment
or energy costs for air pollution control devices.
The results of a study of the economic and technical feasibility of various
types of industrial driers have been presented by Akers, et al, (8), They con-
cluded that rotary drum driers are acceptable for poultry manure drying from
a technical viewpoint. For small operations, agitated pan driers were found
to be the most advantageous from both economic and technical aspects. For
operations with an excess of one million birds, pneumatic driers had the lowest
direct costs.
While the use of industrial type driers should not be discounted as a poten-
tial poultry waste management technique, their feasibility is clearly
dependent on marketing of the finished product as a fertilizer or soil con-
ditioner or a feed ingredient. The ability to realize this potential appears
to be limited. In that design information concerning machine drying is avail-
able from various manufacturers, further discussion of this topic does not
appear to be warranted.
24
-------
Several approaches to in-house drying of poultry manure have been developed.
Bressler and Bergman (1) utilized a high velocity, 2.5 m/sec (500 ft/min),
unheated air stream above the manure surface. A stirring device similar to a
spike tooth harrow was used for mixing to expose new surfaces to the air-
stream. This was a continuous flow system with no storage capacity. Moisture
content of manure from this system ranged between 26.1 and 50.5 percent, wet
basis, with the lowest moisture contents occurring during the summer months.
Sobel (9) achieved moisture contents of 29 to 35 percent wet basis, using a
forced air, undercage drying system. This system differed from the previous
approach in that an air duct with a slot outlet was used to direct a uniform
airstream over the poultry manure surface. A 7.6 cm (3 in.) accumulation of
manure was maintained under the birds. This prevented sticking of manure to
the dropping boards and provided a retention time of 5 to 8 days. The shallow
bed of manure was mixed several times per day exposing new surfaces to the
airstream.
One of the drawbacks of undercage, continuous flow drying concerns storage.
Sobel and Ludington (10) have reported that the moisture content of dried
manure should not be greater than 30 percent, wet basis, for successful
storage. At higher moisture contents, malodors develop and the material
regains its sticky and adhesive characteristics. While moisture reduction to
30 percent can be achieved with undercage drying, consistent performance at
this level has not been possible. Therefore, supplemental treatment either in
the form of composting or heated air drying appears necessary to permit
storage.
Perhaps the most viable alternative for the drying of poultry manure is under-
cage drying in combination with a high-rise type house. In addition to the
advantages of drying delineated earlier, this approach also provides
acceptable storage for one or more years without supplemental treatment or
handling.
3.2 Objectives
The objectives of this chapter are to:
A. Present a discussion of the development and a description of
high-rise, undercage drying of poultry manure;
B. Discuss the theoretical concepts germane to the drying process;
C. Describe the experimental basis for and present the development
of a rational process design approach for high-rise, undercage
drying;
D. Outline process design methodology;
E. Discuss physical design considerations.
25
-------
3.3 The High-Rise, Undercage Drying System for Poultry Manure
The development of the high-rise, undercage drying system for poultry manure
can be traced to the use of deep pits under caged hens to provide long term
manure storage. Early cage systems utilized shallow manure collection pits
which required frequent cleaning. The deep pit house which provided long
term manure storage was a further development. With this system, a 1.5 m to
2.4 m (5 ft to 8 ft) deep manure collection and storage area_was located beneath
the cages and normally below grade, hence the name deep pit.
Continuing development led to the original high-rise poultry house design.
This differed from the deep pit only in that the bottom of the manure storage
was located at or slightly above grade. This resulted in a two story building
with the cages located on what would be the second floor. This change was
made to eliminate the problem of water infiltration. Neither the shallow pit,
the deep pit, nor the original high-rise house contained any provision for
manure drying.
The high-rise undercage manure drying system, which will be the subject of
discussion in this chapter, refers to the use of unheated, ventiliation
air for manure drying within a high-rise poultry house. Therefore, the
design of the ventilation system is a key factor in the manure drying process.
Figures 3.3, 3.4 and 3.5 are cross-section, plan, and isometric views respec-
tively of a typical poultry house employing the high-rise system of manure
management. Banks of the exhaust ventilation fans are located in the manure
storage area. Ventilation air enters the building through a slot inlet
located at the eave level of the building. The air then passes through the
cages, passes over the manure, and is finally exhausted to the atmosphere.
As shown in Figures 3.3 and 3.4, circulating fans are located in the manure
storage area to provide more uniform air circulation over the manure surface.
This design differs from the early high-rise houses in the location of all
ventilation fans and the use of circulation fans in the manure storage area.
With either flat deck or full stair-step cage systems, manure accumulates
in a series of ridges and valleys conforming to the cage layout when drying
occurs. These ridges are formed under the center of the cages with valleys
under feed and water troughs and where cages are joined (Figure 3.6). With
the triple deck cage system, ridge formation is less pronounced. The ridges
are important since the surface area of the accumulated manure is increased,
thus enhancing drying.
3.4 Theoretical Considerations
The removal of moisture from poultry manure can be accomplished by either
mechanical or evaporative processes. However, evaporation is the process of
interest in this discussion of undercage poultry manure drying in a high-rise
poultry house. The objective of this section is to discuss the principles
of evaporative drying and provide the theoretical basis for the system design
relationships which will be presented subsequently.
26
-------
INLETS FOR
VENTILATION AIR
CAGES
Figure 3.3. Cross-section of a typical
undercage manure drying.
high-rise poultry house with
27
-------
EGG
ROOM
c
-« — g- AIR
-8— »-
MANURE DRYING 8 STORAGE AREA
— 8-
-8 — >•
*?\
-^
VENTILATION FAN BANK
CIRCULATING FAN
Figure 3.4. Plan view of a typical high-rise, undercage manure drying
system showing location of drying air circulating fans.
Figure 3.5. Isometric view of a high-rise poultry house.
-------
Figure 3.6. Ridge and valley formation in a high-rise,
undercage manure drying system.
29
-------
Evaporation is a characteristic of all liquids. It is the change in state
from the liquid to the gas phase. While the terms drying and dehydration are
normally used in conjunction with the removal of moisture from organic
materials such as sewage sludges, various agricultural products, and animal
manures, the reduction in moisture content is due to the evaporative process.
Thus, the terms drying or dehydration merely represent specific cases of the
evaporative process.
The terms drying and dehydration commonly are used interchangeably. However,
their precise meanings differ. Drying applies to any reduction in moisture
content down to but not exceeding the equilibrium moisture content of the
material in question. Dehydration is the reduction in moisture content to
levels below the equilibrium moisture content.
Evaporation can be best understood by considering the physical structure of
water. Any quantity of water is made up of a large number of molecules, each
of which are in constant motion. As the result of kinetic energy exchanges
between colliding molecules, some molecules acquire sufficient energy to over-
come attractive forces and escape into the air as water vapor. Although
molecules are continuously escaping the water surface, others are returning.
The rate of evaporation is determined by the difference in the two rates.
Condensation occurs when more molecules return to the body of water than
escape.
Immediately adjacent to a water surface is a thin layer of air which is in
thermal equilibrium with the water. This film is saturated with water vapor.
If the air above this film has a lower moisture content, water vapor will be
dispersed away from the liquid surface and evaporation will continue. The
rate of evaporation is dependent on the difference in moisture content between
the saturated film and that of the surrounding air.
The moisture content of air can be expressed in several ways. They include
vapor pressure, absolute humidity, and relative humidity. However, both
absolute and relative humidities are calculated from vapor pressure. The
behavior of water vapor in air closely follows the general gas laws including
Dal ton's law of partial pressures. This law states that the pressure exerted
by a mixture of gases is equal to the sum of the pressures that each gas
would exert separately. The pressure that each individual gas, i.e., water
vapor, exerts separately is termed the partial pressure of that gas. The
partial pressure of water vapor in saturated air is called the saturation
vapor pressure. The saturation vapor pressure and thus the moisture holding
capacity of air is a function of temperature. Although saturation vapor
pressures can be calculated using gas laws, experimentally determined values
such as those presented in steam tables are considered to be more accurate (11).
The rate of evaporation is dependent on the difference between the vapor
pressure of the saturated air film immediately adjacent to the water surface
and the vapor pressure of the surrounding air. This principle, Dalton's Law
(12), is expressed by:
E = C(P - P ) (3.1)
30
-------
where: E = rate of evaporation, in./day
C = a coefficient dependent on barometric pressure, wind
velocity and possibly other variables, day'1
P = the vapor pressure in the air film next to a water
s surface which is the saturation vapor pressure
corresponding to the temperature of the water, in. Hg
P = the vapor pressure of the surrounding air, in. Hg
8.
Dal ton's Law was expanded by Rohwer (13) to precisely define the effects of
barometric pressure and wind velocity to predict evaporation from lakes and
reservoirs. The Rohwer equation is:
E = 0.771 (1.465 - 0.0186B)(0.44 + 0.118W)(Pc - P ) (3.2)
s d
where: B = barometric pressure, in. Hg
W = wind velocity, miles per hr
and E, P and P as previously defined.
s a
Although research (5) has shown that the moisture loss from a manure surface
is less than that from a water surface, the Rowher equation is useful in
illustrating the principles of evaporative drying. As shown in Equation 3.2,
evaporation will occur even under conditions of no air movement providing a
vapor pressure differential exists. Air movement enhances evaporation due to
the renewal of air in contact with the saturated air film.
The evaporative removal of moisture from many materials including poultry
manure involves two processes. They are the movement of moisture from
within the material to the surface and the evaporation of water from the
surface. Based on the predominance of either factor, the drying process can
be divided into two phases, the constant and falling rate periods. During the
constant rate period, the material contains so much water that liquid surfaces
exist. Under this condition, moisture will evaporate in a manner comparable
to that from a free water surface. The rate limiting step in the constant
rate phase is the mass transfer of water vapor from the saturated film to the
vapor phase. Conversely, the falling rate period is characterized by the
absence of liquid surfaces. In this period, the movement of moisture to the
surface of the material is the rate limiting step.
In a study of the drying characteristics of poultry manure (5), drying curves
indicate that drying to a moisture content of approximately 30 percent»wet
basis (w.b.),is a constant rate process. Beyond this point, internal movement
of water controls the evaporation rate. Research (1, 10) has shown that
drying of poultry manure to a moisture content of 30 percent w.b. is effective
in reducing malodors and further moisture reduction produces increased dust
problems (Figure 3.1). Therefore, the constant rate phase of drying is the area of
31
-------
principal concern in poultry manure drying and further discussion will be
limited to this topic.
For constant rate drying, mass transfer of moisture is proportional to the
exposed surface area, the difference in vapor pressure, and factors such as
air velocity expressed as a mass transfer coefficient. Mathematically, the
relationship between the above factors and the drying rate can be expressed
in terms of the following heat or mass balance.
' V <% - P.) • -
where: dw/dt = drying rate, mass of water evaporated/time
f = water-vapor transfer coefficient at the water-air
v interface, mass/time-area-pressure
A ~ water surface area
P = saturation water-vapor pressure at t , pressure
P = water-vapor pressure in the drying air, pressure
a
ff = thermal conductance of the air film at the water-
air interface, energy/time-area-temperature
t. = air temperature
t = water surface temperature
h- = latent heat of water at t , energy/mass
The water vapor transfer coefficient, f , can be regarded as the diffusivity
of vapor through air (11). In the transfer of water vapor from the surface
of a solid, the vapor must pass through a laminar layer of moist air before
entering the adjacent turbulent zone as shown schematically in Figure 3.7.
The value of f is a function of air velocity in combination with several
other factors. Figure 3.7 also illustrates the decrease in water vapor pres-
sure from the saturated air film immediately adjacent to the liquid surface
to that of the surrounding air as previously discussed.
Equation 3.3 which is presented by Henderson and Perry (11) in a discussion
of the drying of agricultural products is also discussed by Metcalf and Eddy
(14) in relation to the drying of sewage sludge. Several factors should be
noted in relation to Equation 3.3. First, the drying rate can be expressed
as a function of either temperature or vapor pressure. This is due to the
fact that saturation vapor pressure is a function of temperature. Second,
32
-------
Figure 3.7. Change of partial pressure of water vapor with distance
from surface for a constant drying-rate condition (after 11).
33
-------
Equation 3.3 is merely a restatement of Dalton's law (Equation 3.1) if the
heat relationship is excluded.
The theoretical concepts presented herein served as the basis for the develop-
ment of a rational process design approach for high-rise house, undercage
manure drying systems. Discussion of the development and presentation of the
resulting process design equations will follow.
3.5 A Process Design Approach
Although the concept of high-rise, undercage poultry manure drying has been
in existence for several years, a rational approach for the process design of
these systems has been lacking. Design of existing systems has been arbitrary
with performance ranging from marginal to excellent. Unfortunately, the lack
of defined design relationships has precluded understanding of the reasons
for success or failure and the opportunity to optimize system performance.
The results of a recently completed investigation by Sobel (15) have for the
first time provided the basis for a rational design approach for these systems.
The objectives of this system are:
A. Briefly describe the system studied;
B. Discuss the results of the investigation not only in terms of
final waste characteristics but also the parameters identified
as important to system performance;
C. Present the development of a design relationship expressing
surface manurial moisture content as a function of the identified
parameters;
D. Illustrate the relative importance of each variable to overall
performance.
3.5.1 System Description
The high-rise drying system evaluated by Sobel (15) was located on a commercial
poultry farm. The physical dimensions of the structure were 12.2 m wide by
102.4 m long (40 ft x 336 ft) with an egg handling area located at the one
end of the building (Figure 3.4). The side wall height was 4.9 m (16 ft).
This permitted location of the base of the manure collection and storage area
slightly above grade.
The building had a design capacity of 30,000 hens contained in a flat deck
cage system. Feed and egg handling was completely mechanized. A time clock
controlled, continuous flow through-type watering system was used. The cages
were located approximately 24 m (8 ft) above the base of the manure storage
area. The base of the manure storage was 15 cm (6 in.) of fine cinders over
soil.
Bird environment was controlled by 12 thermostatically controlled 91 cm
(36 in.) exhaust fans placed in three banks of four fans located in the side
34
-------
wall of the manure storage area (Figure 3.3 and 3.4). Each fan delivered in
excess of 4.5 m3/sec (9500 ft^/min) of air at a static pressure of 12.4
pascals (0.05 in. H?0), gauge. Fresh air entered the building through
manually controlled slot inlets located at the junction of the sidewall and
roof. Within the manure storage area, eight fans were used to circulate
ventilation air over the accumulated manure. Three fans (91 cm, 0.37 kw)
were located along each side of the storage area and one fan (61 cm, 0.19 kw)
was positioned for cross movement of air at each end of the storage area.
This provided a circular pattern of air movement over the accumulated drop-
pings. The pattern of air movement and location of the circulating fans are
shown in Figures 3.3 and 3.4.
It should be noted that with the exception of the 4.9 m sidewall height, the
location of the ventilation fans, and the presence of the circulating fans in
the manure storage area, this building was designed in accordance with conven-
tional practices employed in the northeastern United States. No special
provisions regarding insulation or ventilation airflow rates were made.
3.5.2 Results
System performance throughout the three years of the study was excellent. At
the end of each year at a time coinciding with flock replacement, the previous
year's manure accumulation was removed. Average moisture content at the time
of removal was 50, 50, and 47 percent, wet basis, respectively for each of
the three years of the study (15). The absence of malodors was characteristic
of both the accumulation and cleanout phases of operation. In addition, no
problems were encountered using solid manure handling equipment such as front-
end loaders and conventional manure spreaders for manure removal.
The parameter used to evaluate overall system performance was the moisture
content of the ridge surface. This was determined from samples taken from
the ridges of the manure accumulation such as in Figure 3.3. It was necessary
to use this approach because the drying rate varied over time due to uncon-
trollable variables such as vapor pressure differential. Therefore, an
accurate analytical determination of overall system moisture content during
the accumulation phase was not possible. A summary of the data collected for
the years 1970-71 and 1971-72 is presented in Table 3.1.
As shown in Equation 3.3, one of the variables affecting drying rate is
surface area. Normally surface area would be constant. However, this is not
true in a high-rise house manure drying system due to the formation of ridges
and valleys which increase surface area with time. In order to quantify this
variable, measurements of manure depths in ridges and valleys were made
throughout the second year of this study. The results of these measurements
were used to determine the increase in surface area over initial conditions.
This increase was expressed as an area factor as follows:
Distance Up and Down Ridges /_ .»
Area hactor - width Qf Manure storage Area (6^>
35
-------
TABLE 3.1. SUMMARY OF HIGH-RISE, UNDERCAGE MANURE DRYING DATA FOR 1970-71 AND 1971-72 (15).
1970-71
Cumulative
Operation
Time, Days
66
87
128
195
248
328
Bird
Density,
BD o
Birds/m
23.0
22.4
21.4
20.6
20.3
19.6
Area
Factor*
AF
1.104
1.137
1.203
1.310
1.395
1.523
Temperature
Dryinq Air
10(est)
8
10.5
24
21.5
14
, ""C
Manure
10(est)
9
11
22
25
28
Vapor
Drying Al'r,P
pascals
857
766
889
2068
1808
1107
Pressure
** Saturation, p ***
pascals
1224
1136
1318
2671
3158
3720
Vapor Pressure
Differential
(P -P ), pascals
j d
367
370
429
603
1350
2613
Drying Air
Velocity,
m/sec
0.5
1.0
1.5
0.5
1.0
1.5
0.5
1.0
1.5
0.5
1.0
1 .5
0.5
1.0
1.5
0.5
1.0
1.5
Surface
Moisture Content
Dry Basis, % Wet Basis, %
253.3
>
196.7
314.9
207.7
236.7
263.6
178.6
131.5
134.7
119.3
90.1
123.2
72.4
29.2
141.5
40.6
30.5
71.7
_
66.3
75.9
67.5
70.3
72.5
64.1
56.8
57.4
54.4
47.4
55.2
42.0
22.6
58.6
28.9
23.4
Calculated from regression equation AF - 0.0016 (cumulative time of operation, days) + 0.998
**Pa is the vapor pressure of the drying air at the observed temperature of the storage air of a relative humidity
of 70%. Relative humidity was not measured at each sampling event and was assumed to be 70%, a value observed
in several measurements.
***PS is the saturation vapor pressure of air at a temperature equal to that of the manure.
-------
TABLE 3.1. SUMMARY OF HIGH-RISE, UNDERCAGE MANURE DRYING DATA FOR 1970-71 AND 1971-72 (15) (CONTINUED).
Cumulative Bird Area Temperature, °C Vapor Pressure Vapor Pressure Drying Air
Surface
Operation Density, Factor* Drying Air Manure Drying Air, P ** Saturation, P *** Differential Velocity
Time, Days BD 2 AF pascals a pascals s (P- P,), pascals m/sec
Birds/nT s a
Moisture
Dry Basis,
Content
Wet Basis,
1971-72
59 25.4 1.092 14 13
86 25.0 1.136 11 11
116 24.4 1.184 12.5 14.5
143 24.1 1.227 11.5 15
184 23.8 1.292 11.5 15.5
213 23.5 1.339 26.5 24.5
240 23.2 1.382 20.5 23.5
267 23.0 1.425 29 32
305 22.7 1.486 22 30.5
339 22.4 1.540 21 30
355 22.3 1.566 14 28
1148
922
1038
957
957
2440
1688
2778
1870
1747
1107
1526
1318
1640
1700
1761
3055
2858
4802
4368
4231
3720
378 0.5
0.7
1.3
396 0.5
0.7
1.3
602 0.5
0.7
1.3
743 0.5
0.7
1.3
804 0.5
0.7
1.3
615 n.5
0.7
1.3
1170 0.5
0.7
1.3
2024 0.5
0.7
1.3
2498 0.5
0.7
1.3
2484 0.5
0.7
1.3
2613 0.5
0.7
1.3
230.0
266.3
219.5
257.1
192.4
198.5
258.4
232.2
172.5
177.0
187.4
133.1
175.5
142.1
81.2
126.8
61.3
_
84.2
-
116.9
115.0
68.6
74.8
71.2
61.0
126.8
103.7
102.4
102.4
94.9
44.5
69.7
72.7
68.7
72.0
65.8
66.5
72.1
69.9
63.3
63.9
65.2
57.1
63.7
58.7
44.8
55.9
37.9
_
45.7
-
53.9
53.5
40.7
42.8
41.6
37.9
55.9
50.9
50.6
51.1
48.7
30.8
Calculated from regression equation AF = 0.0016 (cumulative time of operation, days-) .+ 0.998.
**P is the vapor pressure of the drying air at the observed temperature of tne storage air of a relative humidity
a of 70%. Relative humidity was not measured at each sampling event and was assumed to be 70%, a value observed
in several measurements.
***P is the saturation vapor pressure of air at a temperature equal to that of the manure.
-------
The observed change in area factor with time for the 1971-72 laying cycle is
presented in Figure 3.8.
Air velocity was not uniform over the accumulated manure surface due to the
nature of the air stream from the circulating fans and the irregular manure
surface (Figure 3.6). The velocity of the airstream decreased with distance
from the fan but the width of the stream increased. Observed velocities at
various locations in the manure storage area ranged from 0 to 2 m/sec (0 to
400 ft/min). To develop an understanding of the relationship between air
velocity and moisture removal, surface moisture contents were determined at
sites exposed to three different air velocities over time. The velocities
selected were 0.5, 1.0, and 1.5 m/sec (100, 200 and 300 ft/min) in 1970-71
and 0.5, 0.7 and 1.3 m/sec (100, 140 and 250 ft/min) in 1971-72. While
velocity varied as to location within the manure storage area, variation was
not significant with time. Therefore, samples for surface moisture content
determinations were taken at set locations and velocity was considered
constant over time at each location. Tabulated values are presented in
Table 3.1. The observed relationships between moisture content at sites
exposed to different air velocities and cumulative time of operation are
shown in Figures 3.9 and 3.10. As shown, moisture content decreases with
time of operation with air velocity remaining constant. This illustrates
that moisture removal is a function of several factors, not only air velocity.
Temperatures of the drying air in the manure storage area as well as in the
accumulated manure near the surface were measured continuously during 1970-71
and 1971-72. Data for temperature corresponding to each moisture content
sampling event are presented in Figures 3.11 and 3.12. During 1970-71, the
temperature differential over the first 200 days of operation was minimal.
Following that time period a significant differential occurred. The same
general pattern was repeated during 1971-72. The increase in manurial tempera-
ture over the temperature of the drying air was attributed to biological heat
production.
Drying in general is a physical treatment process which provides odor control
by limiting microbial activity through the removal of water. Reduction of
the moisture content of poultry wastes to 10 to 15 percent, wet basis, has
been reported to inhibit microbial growth (10). However, observed manurial
moisture contents (Table 3.1) did not approach this range of values. The
conclusion that microbial activity was not measurably limited is supported
by the observed biological heat production. Microbial heat production is a
manifestation of the inefficiency in the transformation of a substrate into
energy for synthesis and maintenance. The absence of malodors suggests that
the microbial activity was predominately aerobic.
Drying air and manurial surface temperatures were used to determine the vapor
pressure differential at each sampling event. Saturation vapor pressure
values were obtained from standard tables of the thermodynamic properties of
moist air (16). The vapor pressure of the drying air was determined from
saturation values at the observed temperature and an assumed relative humidity
of 70 percent. Relative humidity was not measured at each sampling event; the
assumed value of 70 percent was observed on several occasions.
38
-------
2.0
1.8
o:
O 1.6
h-
o
<
u_
< 1.4
UJ
1.2
1.0
0
I
40 80 120 160 200 240 280 320
CUMULATIVE TIME OF OPERATION, days
360
Figure 3.8. Area factor as a function of cumulative time of operation,
1971-72 (15).
-------
'0 60 120 180 240 300 360
CUMULATIVE TIME OF OPERATION, days
Figure 3.9. Moisture content as a function of operation time,
1970-71 (15).
O
5H
LULL)
^•-
-------
The change in observed vapor pressure differential with time for the years
1970-71 and 1971-72 are shown in Figure 3.13. The significant increase in
vapor pressure differential following the first 200 days of operation for
both years is the result of the increase in the temperature differential
resulting from biological heat production (Figures 3.11 and 3.12). Since
vapor pressure differential is the principal driving force for moisture
removal (Equation 3.1 and 3.3), it appears that biological heat production
which results in higher saturation vapor pressures at the manure surface is
an important factor in high-rise, undercage drying. However, definition of
the environmental conditions which enhance biological heat production in these
systems and thus the ability to control and predict this phenomenon is lacking
at this time.
3.6 Development of a Process Design Relationship
A mathematical understanding of moisture removal in the high-rise, undercage
drying system is necessary to the development of a rational design approach.
However, direct application of a relationship such as Equation 3.3 is not
possible. Information concerning the water-vapor transfer coefficient, f ,
for poultry manure is lacking. Therefore, an emperical approach was used to
develop a mathematical model of this drying system utilizing the theoretical
concepts previously discussed. Data collected during the previously described
three year study was used.
For the high-rise drying system, the average drying rate for the constant rate
drying phase over time, dĄ/dt, can be expressed in terms of the initial
moisture content, M , of the manure measured on a dry basis, the system mois-
ture content, M., at any time t measured on a dry basis and the production of
total solids, P, over time t.
af -
-------
o
o
LJ
Q:
o:
UJ
QL
2
UJ
h-
30
20
10
MANURE
0
0 50 100 150 200 250 300
CUMULATIVE TIME OF OPERATION, days
Figure 3.11. Manurial surface and drying air temperatures,
1970-71 (15).
350
UJ
cc
ID
cr
LJ
Q.
^
LL)
30
20
10
MANURE
0
0 50 100 150 200 250 300
CUMULATIVE TIME OF OPERATION, days
Figure 3.12. Manurial surface and drying air temperatures,
1971-72 (15).
350
42
-------
2800
-g 2400
o
o
Q.
2000
LU
Ł 1600
li-
u_
CO
en
t±j
1200
800
QC
O
g 400
1971-72
1970-71
0
50 100 150 200 250 300
CUMULATIVE TIME OF OPERATION, days
350
Figure 3.13.
Change in vapor pressure differential with time of
operation (15).
43
-------
pressure differential increased with time but differed between the two years
(Figure 3.13). Moreover, air velocity differs with location due to the nature
of the air stream from the circulating fans. Thus, system moisture content
at any specific time can not be predicted and is difficult to measure except
upon removal and complete mixing of the accumulated manure.
However, it is possible to determine the surface moisture content of the
accumulated manure and define the relationship between surface moisture con-
tent and the values of the variables affecting the drying process. For the
high-rise, undercage drying process, this approach is meaningful in that the
time of surface area exposure for a discrete quantity of manure and thus the
opportunity for evaporation is limited by new manure deposition creating a
new surface. System moisture content is simply the summation of surface
moisture contents over time.
The manurial surface moisture content at any time, t, can be expressed
mathematically as a function of the variables affecting moisture removal as
follows:
sf
=; f \(™-) W
' \cn/» * >
- P
,)]
(3.5)
where:
M
sf
AF
BD
= manurial surface moisture content, dry basis,
mass of water/mass of total solids - percent
= area factor, dimensionless
= bird density per unit of manure collection area,
birds/m2
V = velocity of the drying air, m/sec
P = saturation water vapor pressure at the temperature
of the manure surface, pascals
P = water vapor pressure in the drying air, pascals
Sobel (15) utilized the data presented in Table 3.1 to determine the mathe-
matical relationship between M f and the variables in Equation 3.5. Initially,
the correlation between each variable (AF/BD, V, and P - P ) individually with
M f was examined. However, this approach was unsuccessful. Examination of
the correlation between the product of V and Ps - Pa reduced variation and
indicated that a non-linear relationship existed between (V), (Ps - Pa) and
M f. Multiplication by the area factor-bird density ratio, AF/BD,improved the
correlation, and it was found that the relationship was of the form Y = aXb
with X defined as:
X =
(V)
- P
(3.6)
44
-------
Thus, Equation 3.5 can be restated as:
Msf = aXb (3.7)
Regression analysis was used to determine the values for the coefficient a
and the exponent b. This produced the following relationship (Figure 3.14):
Msf = 800 X"0'494 (3.8)
To verify the accuracy of Equation 3.8 in predicting surface moisture content
under specific conditions, this equation was used to calculate values for
manurial surface moisture content at the beginning and end of the 1971-72
manure accumulation cycle. These predicted values were compared with the
average of observed values determined during removal of the accumulated
manure. Surface samples from various locations were composited to establish
an average surface moisture content at the end of the manure accumulation
cycle. Moisture values determined from samples taken at the bottom of the
manure accumulation were used to estimate the average surface moisture content
at the begining of the accumulation cycle. It appears reasonable to use moisture
values at the bottom of the accumulated manure as representative of initial
conditions in that the major evaporation of moisture occurs at the manurial
surface.
Predicted values for manurial moisture contents at the begining and end of
the 1971-72 manure accumulation cycle are presented in Table 3.2. Average
values for the variables defining surface moisture content (Equation 3.6) and
the observed moisture content values are also included.
The predicted value of 317 percent, wet basis (76 percent dry basis) was in
good agreement with the average moisture content observed at the bottom of
the manure accumulation of 276 percent, dry basis (73 percent, wet basis)
(Table 3.2). The predicted surface moisture at the end of the manure
accumulation cycle was 99 percent, dry basis (50 percent, wet basis). Again
the agreement between the predicted and observed values was reasonable
suggesting the validity of Equation 3.8. It is recognized that these compari-
sons between predicted and observed results are not entirely independent,
since values used in the comparisons also were used in the development of
Equation 3.8. Unfortunately, no independent data was available.
One limitation of Equation 3.8 is that the variable bird density (BD)
(Equation 3.6) does not permit introduction of the quantity of moisture
excreted per bird-day as a variable. Bird density is an indirect expression
of the mass of water excreted per unit area of manure storage per day. This
is based on a single value for mass of water excreted per bird-day and thus
has a fixed upper limit. As discussed in Chapter 2, moisture excretion
appears to be a function of feed characteristics. Therefore, it is possible
to have a higher moisture loading per unit area per day, with higher values
of moisture excreted per bird-day. In the study by Sobel (15)- the moisture
excreted per bird-day was 99 gm. A bird density of 20 birds/m of manure
collection area resulted in a maximum moisture loading of 1980 gm hLO/m .
If feed characteristics increased moisture excreted to 110 gm FLO/bird-day,
45
-------
TABLE 3.2. COMPARISON OF PREDICTED AND OBSERVED MOISTURE CONTENTS AT THE
BEGINNING AND END OF THE 1971-72 MANURE ACCUMULATION CYCLE
Bird Average Average
Area Density, Velocity, Vapor Pressure
Factor birds/m^ m/sec Differential, Pa
Initial 1.0 26.9 0.40 439
Final 1.5 21.5 0.59 1688
2 X, Msf,* Msf,t
/ m w m up ~\ Dry Dry
^bird'^sec'^ ' Basis Basis
6.53 317 276
69.49 99 77
* Predicted value
t Observed value
-------
400
H
Z
LJ
O
O
UJ
CO
O
2
LLJ
IT
Z>
CO
200
100
80
60
40
30
10
= 800X"a494
7 8 10
I I
20
40 60 80 100 200 400
Figure 3.14. Development of surface moisture content predictive equation.
-------
2
maximum moisture loading would be 2200 gm HpO/m . Therefore, if the evapora-
tion rate remained fixed, resulting moisture contents would be higher but not
predicted by Equation 3.8.
Therefore, Equation 3.6 was modified by substituting a moisture loading
factor for bird density. The moisture loading factor combines bird density
and manure characteristics.
MLF = (BD) (HP) (3.9)
2
where: MLF = moisture loading factor, kg HpO/m -day
2
BD = bird density, birds/m
MP = moisture excreted, kg H^O/bird-day
In order to provide a more precise basis for calculation of bird density, bird
density as used in Equation 3.9 is based on cage row width instead of width
of the manure accumulation area. The reason for this change will be described
in detail in the following section on process design methodology.
Regression analysis was again used to determine the values of a and b for
Equation 3.7 with X redefined as:
X1 =
This produced the following relationship (Figure 3.15):
Msf = 2271 X'Y-0.494
The development of a mathematical expression defining the relationship between
moisture content and the associated variables (Equation 3.11) permits the
assessment of the relative importance of each variable. A short computer
program (The Appendix, Figure A-l) was written to examine the relative importance
of each variable in relation to the resultant manure surface moisture content.
This was done by calculation of simulated moisture contents over a range of
values for a selected variable holding the other variables constant. Values
selected for the area factor, air velocity at the manure surface, and vapor
pressure differential are representative of conditions observed by Sobel (15).
In the analysis of the effect of the moisture loading factor, two values were
used for the quantity of moisture excreted per bird-day. They are 81 and 135 gm
H?0/bird-day reflecting high and low energy feeding programs (Chapter 2).
Both values were varied over a simulated decrease in bird density due to
mortality of 117.9 to 87.3 birds/m . The range of values and assumed constant
values for each variable are presented in Table 3.3.
48
-------
10
.o 400
200
LU
O
O
LL)
CC
LJ
O
2
o:
:D
eo
100
80
60
40
10
MSF = 2271 X
R = 0.844
-0.494
I I I I I
II I I I I I 11
I I
I 60 80 100
,1
200
X =
400 600 1000 2000 4000
Figure 3.15. Redefinition of surface moisture content predictive equation.
-------
TABLE 3.3. VALUES USED IN THE SIMULATION OF HIGH-RISE DRYING
Value Used
as a Constant
When Other Parameters Range of Values
Parameter Were Varied as a Variable
Area Factor, dimensionless 1.3 0.9 -1.6
Moisture loading,,
factor, kg H20/m -day 2.06 1.76-3.9
Air velocity, m/sec 0.5 0.25-2.0
Vapor pressure
differential, pascals 1360 100-2720
The results of the simulations are presented in Figures 3.16 through 3.19.
Before considering the results of these simulations, it should be recognized
that while the moisture loading factor and air velocity are controllable
variables, the area factor and the vapor pressure differential are not con-
trollable in a high-rise drying system.
Of the four variables, the increase in area factor due to ridge formation
appears to have the least effect on manurial surface moisture content
(Figure 3.16). The increase of AF from 1.0 to 1.6 reduced the surface
moisture content by only 5.85 percent in the simulation. The magnitude of
this change is similar to that which results from the reduction of bird
density due to mortality over the laying cycle.
The response to decrease in bird density was found to be a 1.9 and 2 0 percent
reduction in surface moisture content respectively for birds excreting 135 and
81 gm H20/bird-day (Figure 3.17). Of greater significance is the difference
in the predicted surface moisture content between birds with high versus low
quantities of water excreted per day.. This difference was 6.1 percent at the
maximum bird density of 117.9 birds/nr (Figure 3.17).
The simulation results showed that the variables of greatest importance are
air velocity and vapor pressure differential. Increasing air velocity from
0.25 to 2.0 meters per second reduced predicted surface moisture content by
25.2 percent (Figure 3 18) The sensitivity of surface moisture content was
even greater with a reduction of 35 percent when the vapor pressure differpn
tial increased from 100 to 2720 pascals (Figure 3.19).
Recognition of the relationships between air velocity and vapor pressure
differential and resultant surface moisture content is important In systems
with no external heat added, large vapor pressure differentials can only be
50
-------
60
UJ
58
O
O
Ł56
en
O
S
a 54
Ł
01
C/)
52
MOISTURE LOADING FACTOR = 2.72 kg H20/m^-day
AIR VELOCITY = 0.5 m/sec
VAPOR PRESSURE DIFFERENTIAL = 1360 pascals
0.9
I.I 1.2 1.3 1.4
AREA FACTOR, dimensionless
1.5
1.6
Figure 3.16. Relationship between area factor and surface moisture content.
-------
on
63
.0
,0 61
o^
h-"
2
Lul
8 59
LJ
or
in
O 57
UJ
o
2
a:
53
2.0
AREA FACTOR =1.3
AIR VELOCITY =05 m/sec
VAPOR PRESSURE DIFFERENTIAL =
1360 pascals
135gms H20/bird-day
NOTE:
RANGE OF VALUES FOR EACH
MOISTURE PRODUCTION RATE
REPRESENTS A 15% DECREASE IN
BIRD-DENSITY DUE TO MORTALITY
81 gms HO/ bird-day
2.4
2.8
3.2
3.6
4.0
4.4
MOISTURE LOADING FACTOR, kg H20/m*-day
Figure 3.17. Relationship between moisture loading factor and surface moisture content.
-------
67
63
59
LJ
o
LJ
a:
CO
o
5
LJ
O
§47
CO
43
39
AREA FACTOR = 1.3
MOISTURE LOADING FACTOR =
2.72 kg H 0/m2-day
VAPOR PRESSURE DIFFERENTIAL'
1360 pascals
0.5 1.0 1.5
AIR VELOCITY, m/sec
2.0
2.5
Figure 3.18. Relationship between drying air velocity and
surface moisture content.
53
-------
90
5s 80
LJ
UJ
on
ID
O 60
LoJ
O
2
50
CO
40
AREA FACTOR = 1.3
MOISTURE LOADING FACTOR= 2.72 kg H 0/m2-day
AIR VELOCITY = 0.5 m/sec
400 800 S200 1600 2000
VAPOR PRESSURE DIFFERENTIAL, pascals
Figure 3.19.
2400
2800
Relationship between vapor pressure differential and
surface moisture content.
-------
achieved through biological heat production in the accumulated manure. While
this production does occur and will be a positive factor in moisture reduction,
it is uncontrollable. Thus, increasing air velocity is the principal process
design variable that can be controlled to achieve low moisture content poultry
manure in a high-rise poultry manure drying system. Another significant
factor is to use birds and feed that reduce the moisture content of the
excreted manure to as low a value as possible.
3.6 Process Design Methodology
The mathematical relationships, Equations 3.9 through 3.11, provide the basis
for a rational design approach for high-rise, undercage drying systems for
poultry wastes. However, utilization of the predictive relationship,
Equation 3.11, as a process design tool requires an understanding of several
factors. Included are available types of cage systems, management practices,
and the nature of the high-rise drying process. Such an understanding is
necessary in order that the limitations of currently available process design
methodology are recognized. Therefore, the objectives of this section are to:
A. Discuss available types of cage systems and management practices
as related to bird density and therefore, the moisture loading
factor,;
B. Present the development and discuss the application of a high-
rise process design relationship;
C. Presentation of a suggested process design methodology.
3.6.1 Available Cage Systems and Management Practices as Related to Bird
Density and the Moisture Loading Factor
As illustrated in Section 3.5, the moisture loading factor (MLF) has a signi-
ficant effect on high-rise drying performance as measured by the manurial
surface moisture content. The MLF is a function of two variables, waste
characteristics and bird density (Equation 3.9). The relationship between
feeding practices and the quantity of moisture excreted per bird-day has been
discussed in Chapter 2. There are two factors that can cause variation in
bird density: a) the type of cage system,and b) the number of birds per cage.
There are three types of cage systems which are used in commercial egg pro-
duction. They are the flat deck, full stair-step, and triple deck cage systems,
A cross-sectional view of each is presented in Figure 3.20. Two standard cage
sizes, 30 cm x 51 err1 or 61 cm x 51 cm, are available with each cage system.
Average cage height is 42 cm. The smaller cages are used for either 4 or 5
hens while the larger cages are used to contain 8 to 10 hens depending on
management practices. Thus, bird density can vary significantly. Details are
presented in Table 3.4.
In practice, the area of manure accumulation is somewhat larger than the cage
area. However, there is a constant relationship between these two factors,
and in this design approach (Equations 3.9 through 3.11) bird density is based
on cage floor area rather than manure accumulation area. Since no overlap of
55
-------
FLAT DECK CAGE
SYSTEM
-AISLE-
FULL STAIR-STEP
CAGE SYSTEM
h* AISLE-
TRIPLE DECK CAGE
SYSTEM
Figure 3.20.
Cross-sectional views of the three predominate types
of cage systems for laying hens.
56
-------
TABLE 3.4. RANGES OF BIRD DENSITY PER UNIT CAGE FLOOR AREA WITH
DIFFERENT MANAGEMENT PRACTICES
Cage
Dimension, cm
30.5 x 50.8
30.5 x 50.8
61.0 x 50.8
61.0 x 50.8
61.0 x 50.8
2
Area, m
0.15
0.15
0.31
0.31
0.31
No. of Birds/Cage
4
5
8
9
10
2
Density, Birds/m
25.8
32.3
25.8
29.1
32.3
cages occurs with the flat deck and full stair-step cage systems, the values
for bird density, presented in Table 3.4 can be used directly in the calcula-
tion of the moisture loading factor (Equation 3.9).
With the triple deck cage system, the overlap of cages (Figure 3.20) results
in a higher bird density based on cage row width than in terms of cage floor
area. Bird densities for this type of cage system based upon cage row width
are presented in Table 3.5.
TABLE 3.5. RANGES OF BIRD DENSITY BASED ON CAGE ROW WIDTH
FOR TRIPLE DECK CAGE SYSTEMS
Cage
Dimension, cm
30.5 x 50.8
30.5 x 50.8
61.0 x 50.8
61.0 x 50.8
61.0 x 50.8
2
Area, m
0.15
0.15
0.31
0.31
0.31
No. of Birds/Cage
4
5
8
9
10
2
Density, Birds/m
31.8
39.8
31.8
35.8
39.8
57
-------
The ranges in values presented in Tables 3.4 and 3.5 illustrate the importance
of defining the type of cages to be used and anticipated management practices
as the first step in high-rise, undercage drying system design.
3.6.2 Development and Application of a High-Rise Drying Process Design
Relationship
The discussion of the high-rise, undercage drying process has focused on the
development of a predictive relationship (Equation 3.11). This relationship
defines the manurial surface content as a function of four variables; area
factor (AF), moisture loading factor (MLF), drying air velocity (V), and the
vapor pressure differential (VPD). The transformation of Equation 3.11 into
a process design equation and its subsequent use depends on an understanding
of the nature of the variables involved.
Of the four variables in Equation 3.11, two variables, AF and VPD, represent
uncontrollable parameters. Moreover, a lack of understanding of the causes
of change over time results in the inability to predict these changes. While
a specified value can be designated or determined for MLF, it also is a
variable in the high-rise drying process which will decrease with time due to
bird mortality. Under normal conditions, a mortality rate of approximately
one percent per month can be expected.
In contrast, the velocity of the drying air, V, can be assigned a desired
value and held constant. Thus, V, represents the principal design and
operating parameter for high-rise, undercage drying systems for poultry
manure. For design, it is necessary to restate the predictive relationship
(Equation 3.11) in terms of the drying velocity. Combining Equations 3.10 and
3.11 results in the following relationship:
AF,
W = 2271 ») M
-------
cycle. Conversely, MLF is at the maximum value (Table 3.1). Thus, the condi-
tions least favorable for drying occur during the start-up period, and the
highest drying air velocities to achieve a specified surface moisture content
are necessary.
It appears that the start-up phase of a high-rise drying system is not only
the least conducive to moisture removal but also the most critical. If
adequate moisture removal does not occur during this period, creation of the
conditions which enhance the drying process, such as formation of ridges and
development of an optimal environment for biological heat production, is
likely to occur. Therefore, the process design of these systems should focus
on the initial period of operation where the highest air velocities are
required.
In utilizing Equation 3.13 to determine the design drying air velocity for
start-up conditions, it is necessary to specify values for AF and VPD that
are anticipated during system start-up. It is also necessary to specify a
value for manurial surface moisture content for this period. This presents
a problem. While it is clear that this value need not approach the desired
final system moisture content, it appears that some degree of moisture reduc-
tion at the initial phase of system operation is critical to create conditions
conducive to subsequent ridge formation and biological heat production. As
the system operates, increases in AF and VPD as well as the decrease of the
MLF will result in increasingly lower surface moisture contents at the
initially selected drying air velocity. The lack of experimental data during
high-rise, undercage drying system start-up necessitates specification of a
design value for manurial surface moisture content based on judgement and
experience. Based upon analysis of results presented by Sobel (15), suggested
design values representative of initial conditions are noted in Table 3.6.
TABLE 3.6. SUGGESTED DESIGN VALUES REPRESENTATIVE OF INITIAL
CONDITIONS FOR HIGH-RISE DRYING PROCESS DESIGN
Parameter Design Value
Area factor 1.0
Vapor pressure differential 325 pascals
Manurial surface moisture content 235 percent, dry basis
3.6.3 High-Rise, Undercage Drying Process Design Methodology
The process design of a high-rise, undercage drying system is a simple procedure
involving only two design equations (Equation 3.9 and 3.13). The following
discussion will outline the necessary steps in determining the required average
59
-------
drying air velocity for this poultry waste management alternative. This will
be followed by a design example intended to illustrate the design methodology
for these systems and also the effect of bird density by considering two
different values for this variable. Finally, the infeasibility of achieving a
large moisture reduction in the initial stage of system operation will be
illustrated.
The following is a summary of the steps in the process design of a high-rise,
undercage drying system for poultry manure:
A. Determine the type of cage system and anticipated number of
birds per cage.
p
B. Determine bird density, birds/m , based on cage row width from
Table 3.4 or 3.5.
C. Measure moisture production, gm ^O/bird-day, or estimate a
value based on feed metabolizable energy content using Equations
2.1 and 2.3 (Chapter 2).
D. Calculate the moisture loading factor (MLF) using Equation 3.9.
E. Select design values representative of initial conditions for
area factor (AF), vapor pressure differential (VPD), and desired
manurial surface moisture content (Mgf) during the start-up
phase of system operation. Values presented in Table 3.6 are
suggested,
F. Calculate average drying air velocity using Equation 3.13.
As an illustration of the high-rise, undercage drying design process, the
following design example will involve the determination of average drying air
velocity for a high-rise system with 30.5 cm x 50.8 cm full stair-step cages.
Designs for both 4 and 5 hens per cage will be considered. The birds will
receive a diet containing 2800 kcal metabolizable energy (ME)/kg feed. The
following is an illustration of the required design steps:
A. Cage system and number of birds per cage has been specified;
B. From Table 3.4, bird densities will be 25.8 m2/bird and
32.3 m2/bird for 4 and 5 birds per cage, respectively;
C. Using Equation 2.1, total solids excreted, gm/bird-day =
-0.038 (2800 kcal/ka) + 138 = 31.6 gm TS/bird-day;
Then using Equation 2.3,
gm HpO excreted/bird-day = 3.59 (31.6 gm TS/bird-day) - 26 4 =
87.0 gm H20/bird-day.
D. Utilizing Equation 3.9, the moisture loading factor for this
situation can be calculated as follows:
60
-------
E.
MLF = (87.0 gffl H?0/bird-day) x (25.8 birds/in ) x (1 kg/1000 gm) =
2.24 kg H90/mS-day. For 5 hens per cage, the MLF increases to
2.81 kg H^O/m -day;
Using design values for the area factor, vapor pressure differential,
and manurial surface moisture content in Table 3.6, the average
drying air velocity for the system can then be calculated using
Equation 3.13.
V =
235
-0.494
- In
- In (325)
2
For a MLF of 2.81 kg HLO/m -day, the required average drying air
velocity increases to 6.85 m/sec.
If this design manurial surface moisture content is reduced to
100 percent, dry basjs, the average drying air velocity for a
MLF of 2.24 kg HpO/m2-day would be 3.83 m/sec. Air velocities
of this magnitude are impractical in a high-rise drying system.
3.7 Physical Design Considerations
Presentation of structural design aspects for the high-rise, undercage drying
system for poultry wastes is beyond the scope of this manual. Information
of this nature is available from other sources such as the Cooperative Exten-
sion Service. However, discussion of physical design considerations which
have direct bearing on the drying process appear appropriate. Included will
be a discussion of:
A. Determination of capacity and location of drying air circulating
fans to meet specified design velocities;
B. High-rise versus deep-pit construction;
C. Manure storage area base construction;
D. Bird watering systems.
3.7.1 Determination of Capacity and Location of Circulating Fans
Perhaps the weakest link in the high-rise undercage drying system design
process concerns the specification of size and location of the drying air
circulating fans in the manure storage area. The basis for determination of
necessary capacity for individual fans and the distance between fans is
limited. The following consists of best estimates based on limited and
incomplete information. Some degree of trial and error should be anticipated.
It is clear that the circulating fans in the manure storage area should be
situated to provide a racetrack pattern of air flow (Figure 3.4). This
eliminates opposing airstream with resultant dead spots. One problem related
61
-------
to the determination of fan capacity requirements to meet a given design
velocity concerns the nature of the airstream. The airstream created by the
propeller type fan commonly used in agricultural applications is not uniform.
As the data in Table 3.7 illustrates, the air stream changes from a narrow,
high velocity to a broader but lower velocity pattern with distance parallel
to air flow from the fan. Thus, uniform velocity over the accumulated manure
cannot be expected.
TABLE 3.7. CROSS-SECTIONAL VELOCITY DISTRIBUTION FROM HIGH-RISE
CIRCULATING FANS* (15)
Distance From Fan
Along Air Flow Distance Perpendicular
Centerline to Air Flow Centerline, m
2.4 0
1.1
2.1
13.4 0
1.1
2.1
Velocity,
m/sec
2.0
0.2
0.2
0.8
0.8
0.3
* Each fan had a capacity of 4.7 m3/sec (10,000 ft3/min).
The determination of required fan capacity can only be based on average
velocity. Fan capacity can be determined on this basis using the following
relationship:
o
Required Fan Capacity, m/sec =
(Design Velocity, m/sec) (Cross-Sectional Area, m2) (3.14)
With the fans situated to provide a racetrack air flow pattern, the cross-
sectional area for each fan will be one-half the cross-sectional area of the
manure storage. For example, consider a system with a design velocity of 0.71
m/sec. The manure storage area will have the cross-sectional dimensions of
2.1 m x 12.2 m. Using Equation 3.14, the required capacity for each fan is:
Required Fan Capacity, m3/sec = (0.71 m/sec) (12.8 m2) =
9.1 m3/sec (19,300 ft3/min)
The second problem related to circulating fans is the determination of the
distance between fans. As shown in Table 3.7, velocity decreases with distance.
62
-------
Results of measurements of velocity at the airstream center!ine with distance
from the fan for three fans are presented in Figure 3.21. Each fan had a
capacity of 4.7 m3/sec (10,000 ft3/min) at zero pascals static pressure.
These measurements were obtained after a year of manure accumulation had
occurred. Variation is due to the irregular manorial surface (Figure 3.6).
In this system, a fan spacing of 35 m (116 ft) was effective in providing an
average drying air velocity of 0.4 m/sec (79 ft/min). Unfortunately, similar
information for fans of other capacities is totally lacking. A spacing of
30 m (100 ft) is recommended for all fan capacities at this time.
3.7.2 High-Rise Versus Deep-Pit Construction
While this chapter has focused on undercage drying in a high-rise poultry
house, the use of this type of system in a deep-pit structure also appears
possible. However, two factors lead to a strong recommendation against this
approach. First, ventilating fans are normally located at bird level in
deep pit houses. Therefore, the frequency of air change and thus removal of
moisture laden air in the manure storage area is lessened. This will reduce
the vapor pressure differential between the manurial surface and the drying
air resulting in a lower evaporation rate.
Second, deep pit construction introduces the potential of water infiltration
into the manure storage area. This factor appears to be the principal reason
for failure of many deep-pit, undercage drying systems. When conversion of
existing deep-pit collection systems to undercage drying is undertaken, water-
proofing of the manure storage area is essential.
3.7.3 Manure Storage Area Base Construction
As noted earlier, the base of the manure storage area in the system monitored
by Sobel (15) was 15 cm (6 in.) of fine cinders over soil. This approach
was used to lower construction costs. To date (1977), this system has been
in operation for six laying cycles. Through the third cycle, it was possible
to use wheel-type loaders for manure removal. However, deterioration of the
base had made the use of track-type equipment mandatory for subsequent clean
out operations. Migration of moisture from the manure to the soil was inves-
tigated and found to be insignificant (15). However, it is suggested that a
material such as concrete be used as a base for the manure storage area to
facilitate manure removal.
3.7.4 Bird Watering Systems
A key factor in the successful performance of a well designed high-rise drying
system is the prevention of leakage from the bird watering system into the
manure storage area. No practical undercage drying system has the evaporation
capacity to remove this additional moisture loading. Three types of watering
systems are currently in use in the poultry industry. They are nipple valves,
cups, and troughs. Experience indicates that in spite of manufacturer's claims,
neither nipple valves nor cups will provide a reliable leak-free watering system.
The only alternative is trough watering systems. With proper maintenance, the
potential for over-flow is minimal. These systems can be time-clock controlled
63
-------
o
Q>
CO
CM
LJ
1.6
1.2
t 0.8
O
O
0.4
NOTE :
I. EACH LINE REPRESENTS
AN INDIVIDUAL FAN.
2. FAN CAPACITY = 4.7 m3/sec.
8
12 16 20 24
DISTANCE FROM FAN, m.
28
32
36
Figure 3.21. Air velocity at the airstream centerline related to distance
from fan with accumulated manure (15).
-------
providing water only over selected time periods of the day. This reduces the
chance of an overflow going undetected for an extended time period.
3.8 Summary
The overall objective of this chapter has been to present a process design
approach for the design of high-rise, undercage drying systems for poultry
wastes. The mathematical design relationships presented are empirical and
based upon experimental observations. However, the development of these
empirical design relationships has been based on concepts fundamental to the
drying process. Also included are a discussion of the development and
description of hiqh-rise, undercage drying, and illustration of pr9cess
design methodology, and a brief discussion of physical design considerations,
3.9 References
1. Bressler, G.E. and E.L. Bergman. Solving the Poultry Manure Problem
Economically through Dehydration. In: Livestock Waste Management.
ASAE, St. Joseph, Michigan. 1971. p. 81-84.
2. Surbrook, T.C., C.C. Sheppard, J.S. Boyd, H.C. Zindel, and C.J. Flegal.
Drying Poultry Wastes. In: Livestock Waste Management. ASAE,
St. Joseph, Michigan. 1971. p. 192-194.
3. Price, D.R., A.T. Sobel, and H.R. Davis. Electric In-House Drying of
Poultry Wastes. ASAE, Paper No. 72-806. St. Joseph, Michigan. 1972.
12 p.
4. Sobel, A.T. Removal of Water from Animal Manures. Proc. Agric. Waste
Management Conf., Cornell University, Ithaca, New York. 1969. p. 347-362.
5. Sobel, A.T. Moisture Removal. Proc. Agric. Waste Management Conf.,
Cornell University, Ithaca, N.Y. 1971. p. 107-114.
6. Cassell, E.A. Studies on Chicken Manure Disposal, Research Report No. 12,
Part II, Chemical Dewatering. New York State Department of Health. 1968,
224 p.
7. Ludington, D.C. Dehydration and Incineration of Poultry Manure. Proc.
National Poultry Industry Waste Management Symposium, Lincoln, Nebraska.
1963.
8. Akers, J.B., B.T. Harrison, and J.M. Mather. Drying of Poultry Manure -
an Economic and Technical Feasibility Study. In: Managing Livestock
Wastes. ASAE, St. Joseph, Michigan. 1975. p. 473-477.
9. Sobel, A.T. Undercage Drying of Laying Hen Manure. Proc. Agric. Waste
Management Conf., Cornell University, Ithaca, N.Y. 1972. p. 187-200.
10. Sobel, A.T. and D.C. Ludington. Management of Laying Hen Manure by
Moisture Removal. AWM 75-01. Dept. of Agricultural Engineering, Cornell
University, Ithaca, New York. 1975. 100 p.
65
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11. Henderson, S.M. and R.L. Perry. Agricultural Process Engineering.
John Wiley and Sons, Inc., New York. 1966. 430 p.
12. Wisler, C.O. and E.F. Brater. Hydrology. John Wiley and Sons, Inc.,
New York. 1959. 408 p.
13. Rohwer, C. Evaporation from Free Water Surfaces. U.S. Dept. of Agricul-
ture. Technical Bulletin 271. U.S. Government Printing Office,
Washington, D.C. 1931.
14. Metcalf and Eddy, Inc. Wastewater Engineering. McGraw-Hill Book Co.,
1972. 782 p.
15. Sobel, A.T. The High-Rise System of Manure Management. AWM 76-01. Dept.
of Agricultural Engineering. Cornell University, Ithaca, New York. 1976.
45 p.
16. Guide and Data Book. Fundamentals and Equipment. American Society of
Heating, Refrigerating and Air Conditioning Engineers, Inc., New York.
1965. 1,000 p.
66
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CHAPTER 4
AEROBIC BIOLOGICAL STABILIZATION OF POULTRY MANURE
4.1 Introduction
Research (1, 2, 3, 4) has demonstrated that aerobic biological treatment
processes can provide a feasible alternative for the management of poultry
wastes and provide the following advantages:
A. Reduction or elimination of offensive odors;
B. An innocuous method for nitrogen removal when required;
C. Waste stabilization through the removal of readily biodegradable
organic compounds;
D. Elimination of breeding conditions for flies and sites which will
harbor rodents.
Aerobic biological treatment processes can be divided into two categories,
fixed film and slurry type processes. The trickling filter and rotating
biological contactor (RBC) are examples of units employing the fixed film
process. Diffused aeration and the oxidation ditch are illustrations of
systems employing the slurry type process.
Both trickling filters and RBC's are designed to aerobically treat dilute
wastes having low concentrations of particulate solids. High particulate
solids concentrations result in clogging of trickling filters thus reducing
performance. With RBC's, particulate solids will accumulate in disc wet
wells reducing the hydraulic retention time (HRT) and can produce septic
conditions. The use of the fixed film process for the stabilization of
animal wastes including poultry manure requires liquid-solid separation prior
to biological treatment. This requires an additional unit process and creates
an additional unstabilized waste stream.
The use of slurry type processes for poultry and other animal manures is
attractive due to the ability to receive wastes with high concentrations of
particulate solids, thus eliminating pretreatment. Both diffused aeration
and the oxidation ditch are slurry type processes that have been evaluated
to determine their potential as undercage systems for the stabilization of
poultry wastes (1, 2, 3). In a pilot plant scale evaluation of undercage
diffused aeration, it was reported that airflow rates capable of meeting
biological oxygen requirements were inadequate to maintain completely mixed
conditions (3). Sizable accumulations of settled solids and diffuser plugging
67
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were major problems based upon desijn recommendations (5). For adequate
mixing in aeration tanks, aeration requirements for adequate mixing should be
five times that for oxygen transfer with these wastes.
At present (1977), the oxidation ditch appears to be the most feasible system
for the aerobic biological stabilization of poultry manure. Therefore, this
discussion will focus on the oxidation ditch. However, it should be recognized
that many of the fundamental concepts and process design relationships discussed
in relation to the oxidation ditch are equally applicable to other slurry type
waste treatment systems.
4.2 Objectives
The objectives of this chapter are to:
A. Discuss the development of the oxidation ditch;
B. Discuss the theoretical concepts germane to aerobic biological
waste stabilization;
C. Describe the experimental basis for and present a rational process
design approach for oxidation ditch aeration of poultry wastes;
D. Present process design examples;
E. Discuss physical design considerations.
4.3 The Oxidation Ditch
The oxidation ditch, also known as the Pasveer ditch, was developed at the
Institute of Public Health Engineering in the Netherlands as a low cost
treatment system for wastewater from small communities and industries (6).
The oxidation ditch consists of a circular or racetrack shaped circuit or
ditch (Ficare 4.1) and an aeration unit. Brush or cage type surface aerators
are used extensively in oxidation ditches (Figures 4.2 and 4.3). These aerators
consist of horizontal revolving shafts with attached blades extending below
the mixed liquor surface. Conventional oxidation ditch aerators serve two
functions; oxygen transfer and mixing.
The oxidation ditch as originally developed was designed to receive unsettled
domestic and/or industrial wastewater and provide treatment as well as sludge
digestion. Employing discontinuous aerator operation, secondary clarification
prior to effluent discharge can be achieved in the ditch. Thus, primary and
secondary clarifiers as well as sludge digestion facilities are not required.
The oxidation ditch is an attractive biological treatment system for livestock
wastes due to its ability to handle wastes with high concentrations of parti-
culate solids. In 1967, it was estimated that about 400 oxidation ditches
were in operation in agricultural applications in the United States (7). Most
of these systems are used for swine wastes but the oxidation ditch also has
been utilized for dairy, beef, and poultry wastes.
68
-------
/AERATION UNIT
\
a\
FLOW
Figure 4.1. Diagram of the basic oxidation ditch.
-------
Figure 4.2!. A brush type surface aerator.
Figure 4.3. A cage type surface aerator.
.
-------
In addition to odor control, the oxidation ditch offers the following advan-
tages as compared to other biological treatment processes:
A. Low capital costs;
B. Requires little attention and maintenance;
C. Once operating properly, has the ability to handle shock loads;
D. Ease of incorporation into production facilities.
Figure 4.4 is a vertical cross-section of an undercage oxidation ditch for
laying hens.
4.4 Theoretical Concepts
The biological stabilization of poultry wastes is a microbial process involving
transformations of carbonaceous and nitrogenous compounds. Knowledge of basic
microbial concepts and transformations provide a basis for the development of
a rational design approach delineating system performance and aeration require-
ments. It is the objective of this section to present a brief review of basic
microbial relationships and to describe transformations of carbonaceous and
nitrogenous compounds and the resulting oxygen requirements. This is followed
by a discussion of various substrate removal relationships and oxygen transfers
4.4.1 General Microbial Concepts
The general biochemical relationship that describes any biological waste treat-
ment process is:
Energy containing metabolizable wastes + (A 1}
microorganisms -> end products + more microorganisms
Only part of the substrate is converted to end products. End products are the
result of biochemical reactions which provide energy for cell maintenance and
microbial synthesis. The remaining substrate is transformed into new cell
mass.
The organic matter initially converted to cellular material can be transformed
subsequently to end products via two mechanisms. One is death of the organisms
which occurs in all biological systems. Following death, cells lyse and the
released organic matter is available as substrate for the remaining micro-
organisms. The other occurs when substrate in the system becomes limiting.
Organisms can metabolize the storage components of their own protoplasm to
acquire energy. This process is termed endogenous respiration. The results
of both mechanisms can be described as:
Microorganisms -> end products + fewer microorganisms (4.2)
The portion of the cellular material metabolized following death and/or via
endogenous respiration is a function of the mean time that the waste has been
71
-------
1.0
co
0 0.6
o
o
O 0.4
BATCH UNIT
40 g/Je SETTLED
POULTRY MANURE SUSPENSION
X
\
*•
X
f
CO
o
CO
o
LJ
o
CO
ZD
CO
1.5
0.8
o-6
I I
BATCH UNIT
40g/jP SETTLED
POULTRY MANURE SUSPENSION
I I
4 8 12
AERATION TIME, days
16
20
Figure 4.4. Removal characteristics of total COD and suspended solids
semi-logarithmic plot (13).
72
-------
subject to treatment. As time of treatment increases, the portion of the
waste transformed to end products increases, and the net yield of cellular
mass decreases.
As described, microorganisms utilize a portion of the available substrate for
the synthesis of new cell mass. Mathematically microbial growth can be
described as:
dX
dt '
(4.3)
where:
X =
t =
y =
dX
dt =
microorganism concentration, mass/volume
time
net specific growth rate, mass/mass-time or time"
growth rate of microorganisms, mass/volume-time
The net specific growth rate is a function of substrate availability. If
substrate is not limited, microbial growth should occur at an exponential
rate. This is not typical of biological waste treatment systems. Normally,
microbial growth is substrate limited.
Under growth limiting conditions, the net specific growth rate is not constant
but is a function of the limiting substrate concentration. Monod (8) and
others have utilized the following equation to describe the interaction between
the net specific growth rate and the concentration of the growth limiting
substrate.
y =
(4-4)
where: y = maximum net specific growth rate at infinite substrate
concentration, time-1
S = growth limiting substrate concentration, mass/volume
kg = a velocity constant equal to the substrate concentration
at one-half the maximum net specific growth rate, mass/
volume
The half velocity constant, k , is a characteristic of the microorganisms and
the given substrate. For agricultural wastes such as poultry manure, organic
carbon should be the growth limiting substrate for heterotrophic microorganisms,
73
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4.4.2 Microbial Transformations of Carbon and Nitrogen - Oxygen Requirements
The carbon and nitrogen transformations represent sources of oxygen utilization
in the stabilization process. Equation 4.5 is a simplified presentation of
the aerobic conversion of organic carbon to cell- mass, C^H^N, and carbon
dioxide.
Organic carbon * 0 W * C°2 <4'5>
, 2
The compounds in poultry manure containing nitrogen, such as proteins and uric
acid, also are metabolized by the heterotrophic microorganisms. This process,
termed ammonification, can be expressed as:
Organic nitrogen .ammonification^ + ^ ., N^+ = QH- (4>g)
While nitrogen is an important nutrient in any biological system, the nitrogen
content of poultry manure exceeds the microbial requirements. Thus in the
absence of nitrification, a residual ammonia concentration will occur. Ammoni-
fication results in an increase in pH due to ionization of NfyOH (Equation
4.6). If ammonium concentrations and pH are sufficiently high, ammonia vola-
til ization will occur.
Under aerobic conditions, ammonia nitrogen can be microbially oxidized to
nitrite and nitrate-nitrogen. Two groups of autotrophic microorganisms are
primarily responsible for this transformation. They are Nitrosomonas and
Nitrobacter. The oxidation of NH^+ to N(h~ is a two step process termed
nitrification and can be expressed as follows:
NH4+ + 3/2 p2 Nitrosomonas ^ + ^ + ^ (^j}
N02- + 1/2 02 ^ N03- (4.8)
The production of hydrogen ions (Equation 4.7) results in a decrease in pH.
A key factor in the design of aerobic waste stabilization systems such as the
oxidation ditch is the determination of exerted oxygen demand. Due to the
large variety of compounds containing organic carbon and the differences in
biodegradability between these compounds, it is not possible to use stoichio-
metric relationships to predict carbonaceous oxygen demand. However, both
biochemical oxygen demand (BOD) and chemical oxygen demand (COD) tests provide
an indirect measure of available substrate in terms of the oxygen equivalent
of organic matter. An advantage of the BOD determination is that unlike the
74
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COD test, it includes only organic matter susceptible to biological degrada-
tion. However, the BOD test is dependent on both the time period and initial
microbial population. It may or may not include nitrogenous oxygen demand
(NOD) depending on the presence or absence of nitrifying microorganisms. This
presents difficulties in comparing the results from raw and treated waste
samples.
The COD test is an alternative. Although this approach includes organic
matter not susceptible to biological degradation, it does not include the NOD
of ammonia nitrogen. If nitrites are present, they will be chemically oxidized
to nitrates. Correction for this factor is simple requiring only concurrent
determination of the nitrite concentration in the sample.
Neither test is ideal but in a situation where change through a treatment
system is being measured, COD appears to have an advantage. By assuming that
a change in COD is due completely to biodegradation, a gm of BOD is satisfied
when organic matter equivalent to a gm of COD is biologically oxidized.
This assumes that there are no reduced compounds to exert an immediate oxygen
demand in terms of simple chemical oxidation. Therefore, definition of COD
removal relationships can be utilized to determine exerted carbonaceous oxygen
demand and aeration requirements.
For the nitrogenous oxygen demand (NOD), more precise stoichiometric relation-
ships (Equations 4.7 and 4.8) are available. Theoretically, 4.57 gm of oxygen
are required to oxidize one gm of ammonia nitrogen to nitrate nitrogen. It
should be recognized that NOD is a function of the ammonification process.
Thus, knowledge of the rate of degradation of organic nitrogen is important to
determination of NOD.
The following general equation describes the rate of oxygen utilization for
the oxidation of carbonaceous matter:
S • lail+ b c x (4-9)
where ^- = rate of oxygen utilization
^pjr = rate of substrate utilization
a = coefficient to convert substrate units to oxygen units
b = microbial decay coefficient
c = coefficient to convert cell mass to oxygen units
X = microorganism concentration
Since both substrate utilization and endogenous respiration are manifested as
COD removed, Equation 4.9 can be rewritten as:
75
-------
dO _ d(CQD) (4 10)
dT ~ dt '
with the inclusion of nitrogenous oxygen demand, Equation 4.10 must be modified
as follows:
nn Atrnn\ d(NH.-N) d(NO?-N)
dO = d(CODl+3>43__^+1J4__2__ (4J1)
where: d(NH4-N) and d(N09-N) are respectively, the rates of oxidation
dt *•
of ammonia to nitrite and nitrite to nitrate.
Thus oxygen demand for various degrees of waste stabilization can be predicted.
4.4.3 Substrate Removal Relationships
While an understanding of the microbial transformations which result in waste
stabilization is important, the identification of the relationships between
system performance and operating parameters is equally necessary for rational
design. This not onlypermits satisfaction of specific treatment objectives
but also allows determination of oxygen requirements (Equations 4.10 and 4.11).
The objective of this section is to briefly review several approaches to
describe substrate removal relationships.
Perhaps the earliest rational approach to slurry type biological treatment
design was developed from the observation that effluent quality was related
to the ratio of substrate loading (F) per unit time and the mass of micro-
organisms (M). As the substrate loading increased, effluent quality
deteriorated. Based upon these observations, the food to microorganisms (F/M)
ratio was established as a design parameter for biological treatment processes
(9). Owens, et al. (10) have investigated the effects of different F/M ratios
on effluent quality in the aerobic treatment of swine wastes. Their observa-
tions of decreasing effluent quality at increasing F/M ratios concurred with
results of previous studies.
Although the F/M concept is fundamentally sound, it is difficult to use due
to problems in determining concentrations of active microorganisms. Tradi-
tionally, volatile suspended solids (VSS) have been used to estimate active
mass. Due to high concentrations of VSS present in animal wastes such as
poultry manure, this method of estimation has little significance in these
wastewaters.
Further attempts to improve the state of the art regarding design of slurry
type biological waste treatment systems have resulted in the development of
mathematical models by several investigators. These models utilize one of
two microbial kinetic relationships, first order substrate utilization or
substrate limited growth.
76
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The first order substrate utilization approach describes the rate of removal
of biologically available organic materials (substrate) as a first order
reaction. This description of microbial kinetics has been' utilized by
McKinney (11), Goodman and Englande (12) and others as the basis for mathe-
matical biological waste treatment models. Prakasam, et al. (13) reported
that removal of chemical oxygen demand in poultry wastewaters can be described
as a first order reaction.
An alternative is to describe microbial growth in waste treatment systems as
substrate limited (Section 4.4.1). Substrate limited growth appears a more
representative description of conditions in biological waste treatment systems
than first order substrate utilization. The concept of substrate limited
growth provides the basis for the treatment model presented by Lawrence and
McCarty (14). In this model, the concept of biological solids retention time,
e , has been proposed as a unifying design parameter for slurry type biological
waste treatment systems in that all system variables can be related to 9 .
Mathematically, e can be represented as:
(4.12)
r — i
L *tTj
where: Xj = total active microbial mass in the treatment system, mass
r AY n
-TT- = total quantity of active microbial mass leaving the system
L J in a unit of time, mass per time.
As e increases, the effluent concentration of the growth limiting substrate
will decrease.
The microorganism concentration is a function of the available substrate
concentration and e . As e increases, the microorganism concentration will
decrease due to endogenous respiration.
The concept of biological solids retention time is not unlike the food to
microorganism (F/M) approach to design slurry type biological systems. When
a value for the microorganism concentration is specified in the F/M approach,
a value for e is specified implicitly but not explicitly. The F/M and e
design approaches have been compared in a treatability study of an oil
refinery wastewater (15) and found to produce similar designs.
Determination of e as defined in Equation 4.12 requires measurement of active
biomass. However, assuming complete mixing resulting in the uniform distri-
bution of microorganisms, the solids retention time (SRT) of the solids can be
used to estimate e . SRT is the theoretical time that solids are retained in
the treatment system and can be expressed as:
SRT =
wt of sol ids in the system
wt of solids leaving the system/time
(4.13)
77
-------
is a function of the active biomass in a system while SRT can be determined
measuring other forms of solids such as volatile, fixed, or total solids.
If the system is completely mixed, SRT is a reasonable estimate of e and is
the key factor in the utilization of this approach. The unifying parameter,
SRT, can be estimated by utilizing an easily determined parameter, solids
concentration.
4.4.4 Oxygen Transfer
In the microbial transformations described in Equations 4.5, 4.7, and 4.8,
oxygen is shown as a reactant. In these microbial mediated reactions, molecu-
lar oxygen serves as the terminal electron acceptor in the oxidation pro-
cesses. The utilization of oxygen as the terminal electron acceptor is the
factor which differentiates between aerobic and anaerobic biological processes.
Earlier sections have been concerned with the identification of sources and
delineation of the magnitude of microbial oxygen demand. This section deals
with the subject of oxygen transfer.
Oxygen is only slightly soluble in water. The rate of oxygen going into
solution is proportional to the differential between the saturated and
equilibrium concentrations. The rate of oxygen transfer can be expressed as:
where: -rp -
K,a =
rate of change of dissolved oxygen concentration
with time, mass/volume-time
overall gas transfer coefficient, time"
C = oxygen saturation concentration for a given liquid
temperature, atmospheric composition and pressure,
mass/volume
C. = actual oxygen concentration at time t, mass/volume
To maintain aerobic conditions, the rate of oxygen transfer should equal or
exceed the biological oxygen requirements of the system. The rate of oxygen
transfer under process conditions can be described as:
where:
N = aKLa (3CS - CL)(V)
N = oxygenation capacity, mass Op/time
a = the ratio of K.a in wastewater to K, a in tapwater,
dimension! ess
3 = the ratio of C in wastewater to C in tapwater
dimensionless
(4.15)
78
-------
V = volume of water under aeration, volume.
The values of K. a and V are functions of the aeration unit and system
volume, and are constant for a given operating condition. C$ is an independent
variable which is related to liquid temperature and atmospheric pressure.
Both a and g are dependent variables. C, is a function of the relationship
between the quantity of oxygen supplied and demand. Both a> g and C,
directly affect the quantity of oxygen transferred under process conditions.
Although a is a function of many factors, a and 3 are primarily related to
mixed liquor characteristics (16). Small quantities of surface active agents
can cause significant reductions in a values (17-19). Downing (18) found
that suspended solids in the range of 1,000 to 6,000 mg/Ł had little effect
on oxygen transfer. However, a was reported to be reduced to 0.2 in a sludge
with a total solids concentration of 10,000 mg/Ł (20).
The value of C, under operating conditions is important in that as the rate
of oxygen transfer, N, increases above that necessary to meet the microbial
oxygen demand, C, will increase. This will result in a decreased oxygen
deficit which represents the driving force for oxygen transfer. This in turn
will reduce the oxygen transfer efficiency of the aerator and increase
operating costs. In any aeration system, minimal, _Ł 2 mg/^-,dissolved oxygen
concentrations (C. ) are adequate.
4.5 Process Design Relationships
The design criteria for aerobic treatment of animal wastes suggested by
Jones, et al., (21) have served as the standard basis of design for these
systems. Both the Midwest Plan Service (22) and Agriculture Canada (23)
suggest this method of design for oxidation ditches. These design criteria
are empirical based upon studies involving swine and dairy cattle wastes.
System volume is determined using the organic loading rate concept. The
recommended loading rate is 0.5 kg BODr/m /day (0.03 Ib BODr/ft /day). The
suggested parameter for oxygen requirement is twice the daily BOD,- loading
assuming that oxygen transfer under process conditions will be 80 percent
of tapwater values.
Although many systems developed from these empirical parameters have performed
satisfactorily, this approach has several disadvantages. It is difficult to
extrapolate between different wastes and environmental conditions. Reasons
for process failures are unclear since the design and operation of the system
is not based on process fundamentals. Possibly the greatest liability of the
empirical approach is its inflexibility. No opportunity exists to adjust
the degree of waste stabilization to specific requirements. This is especially
significant when only a minimal degree of stabilization is required.
During the past 7 years, laboratory, pilot plant, and full scale investigations
of aerobic stabilization of poultry wastes have been conducted by personnel
of the Agricultural Waste Management Program, Cornell University. A common
objective of these studies has been the development of rational design
parameters for these systems. It is the objective of this section to present
79
-------
and integrate the results of these studies into a rational design approach.
This will include discussion of poultry manure as a microbial substrate,
substrate removal relationships and oxygen transfer under process conditions.
4.5.1 Poultry Manure as a Microbial Substrate
Biological stabilization of poultry manure results from its utilization as
microbial substrate. Fresh poultry excreta contains soluble and particulate
organic and inorganic compounds. The inorganic fraction, fixed solids,
contains phosphorus, calcium, and chlorides as major components (24). This
is an expected result since both calcium and phosphorus are fed at levels in
excess of the birds physiological needs to insure adequate uptake. Reported
values indicate that the fixed solids fraction can range between 23 and 33
percent of total solids (Table 2.4).
The organic fraction of these wastes is comprised of both carbonaceous and
nitrogenous compounds. Organic carbon is present as carbohydrates, lipids,
and proteins. The nitrogen in freshly excreted material is almost totally
in the organic form being present as both proteins and uric acid. Between
65 and 75 percent of the nitrogen is in the form of uric acid (25).
Several parameters are used to characterize poultry manure and to assess per-
formance of biological waste treatment processes. These include total solids
(TS), volatile solids (VS), chemical oxygen demand (COD) and organic nitrogen
(ON). Each of these parameters involves the measurement of organic matter.
Due to the complex nature of the organic fraction of poultry manure, substrate
utilization rates for various components and therefore, biodegradability vary
significantly. In a batch study involving the non-settleable components of a
poultry manure suspension, three distinct COD removal rates were observed
(Figure 4.4). The most rapid removal of COD occurred during the first 10
days of treatment. Additional removal resulted from utilization of more
slowly biodegradable compounds. Degradation of soluble organic matter appears
more rapid than that of particulate material. The removal of suspended solids
followed a similar pattern, although two rather than three removal rates were
observed (Figure 4.4).
The results of long term aeration studies (Table 4.1) indicate that a
substantial portion of the organic fraction of poultry manure is either not
or very slowly biodegradable. This material represents the refractory organic
fraction of these wastes. The term refractory fraction refers to that portion
of the waste which is resistant to biological degradation and remains undegraded
at the time when the rate of degradation has decreased to a level as to be
insignificant from an engineering standpoint (27).
Therefore, each parameter used to describe poultry manure which includes the
organic fraction can be subdivided into biodegradable and refractory fractions
as follows:
So = (Vo + Sr (4-16)
80
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TABLE 4.1. OBSERVED REMOVAL OF TOTAL SOLIDS, VOLATILE SOLIDS, AND CHEMICAL
OXYGEN DEMAND IN LONG TERM AERATION STUDIES
Parameter
Percent Removal
Solids Retention Time
4.5 Months (1)*
6.5 Months (26)
7.5 Months (26)
00
Total Solids
Volatile Solids
COD
53
63
63
43
56
60
42
54
*Numbers in parenthesis indicate data source.
-------
where: S = the concentration of any organic parameter in the
0 waste, mass/volume or mass/mass
(Sfa) = the biodegradable fraction
S = the refractory fraction
The refractory fraction can be expressed as:
Sr - R(SQ) (4.17)
where: R = the ratio of the refractory to the total concentration
of any organic parameter, expressed as a decimal.
Since the refractory fraction as defined is unaffected by biological processes,
it will be present in the effluent (S,) from biological waste stabilization
systems.
S-, = (Sb)1 + Sf (4.18)
where: (Sh)n - the unstabilized biodegradable fraction of the
D ' effluent
The refractory ratio (R) can be determined by plotting S-i/S versus (S -SRT)~
(Figure 4.5). Based on the assumption that as the solids retention time (SRT)
approaches infinity, the biodegradable fraction of the influent also approaches
zero. Therefore, the intercept on the ordinate axis represents the refractory
fraction (R) of S . This procedure for the determination of R has been pre-
sented previously°(28, 29, 30).
Knowledge of the magnitudes of the biodegradable and refractory fractions of
poultry manure is important in that it identifies the practical upper limits
of biological stabilization. The refractory fractions of total solids,
volatile solids, chemical oxygen demand, and organic nitrogen were determined
using data reported by Martin and Loehr (2). These data are presented in the
Appendix, Table A-l. The refractory fractions of each parameter were
determined graphically (Figures 4.6 to 4.9). Linear regression analysis was
utilized to determine the value of R, the intercept of the ordinate axis.
These results are summarized in Table 4.2.
4.5.2 Substrate Removal Relationships for Poultry Wastes
Definition of substrate removal relationships are necessary for the rational
design and operation of aeration systems for poultry wastes. The relation-
ships of interest involve the removal of both volatile solids (VS) and total
solids (TS), chemical oxygen demand (COD), and organic nitrogen (ON) as well
as nitrification in certain situations. The removal of both chemical oxygen
82
-------
o
o
o
CO
CO
R = INTERCEPT, mass/mass
I/IS0 SRT), volume/mass-time
Figure 4.5. Graphical plot to determine the refractory fraction of a
partially biodegradable material.
83
-------
.80
.70
.60
.50
.40
.30
0
.01
y = 6.lx + .55
r = .86
.02
I
.03
S0- SRT
.04
Figure 4.6.
Graphical plot to determine refractory fraction of
poultry manure total solids.
C/5
\
CO
.80
.70
0 .60
.50
.40
.30
,01
1
.02
I
y = 4.5x + .43
r = .88
.03
.04
S0-SRT
Figure 4.7. Graphical plot to determine refractory fraction of
poultry manure volatile solids.
84
-------
.80
.70
o .60
/)
•v
n .50
.40
.30
0
y = 3.9x + .60
r = .73
.01
.02
.03
.04
Figure 4.8.
S0- SRT
Graphical plot to determine refractory fraction of
poultry manure COD.
.70
.60
o -50
v.
-------
TABLE 4.2. REFRACTORY AND.BIODEGRADABLE FRACTIONS
OF POULTRY MANURE
Parameter Refractory Fraction, Biodegradable Fraction,
R B
Total Solids
Volatile Solids
Chemical Oxygen Demand
Organic Nitrogen
0.55
0.43
0.60
0.31
0.45
0.57
0.40
0.69
demand and organic nitrogen are important not only in terms of effluent
characteristics but also in the determination of aeration requirements.
Analysis of mass balance results (2, 31) from two full scale evaluations of
aeration systems for poultry wastes has indicated that biological destruction
of TS, VS, COD, and ON can be described as a function of solids retention
time (SRT). Using individual and combined results from these two studies,
the development of both first order substrate utilization and substrate
limited growth kinetic relationships using SRT as the controlling process
parameter was attempted.
Neither the first order substrate utilization nor the substrate limited
growth models provided predicted values that were in good agreement with
observed results. A possible explanation is that more than one removal rate
exists for each parameter due to the complex nature of the waste Phasic
removal patterns have been reported for COD and suspended solids (Figure
t-fy^Io).
The alternative was the development of empirical relationships between SRT
and removal for each parameter. From the analysis of available mass balance
results (2), it was found that for SRT values between 10 and 36 days a
linear relationship provided a reasonable approximation of these relation-
ships. These linear relationships can be expressed in the general form:
Removal, % = A(SRT) + B (4j9)
Linear regression analysis was used to determine values of the coefficients
A and B for each parameter. These results are presented in Fiaurps 4 in
through 4.13 and in the following equations: 9 ' °
86
-------
50
40
30
O 20
UJ
cc
10
0
0
TREATMENT EFFICIENCY, %
0.294 (SRT) + 25.2
— r = 0.56
10 20 30
SRT, days
40
Figure 4.10. Observed relationship between SRT and removal of
total solids.
60
50
40
< 30
O
(T
20
10
0
0
Figure 4.11.
TREATMENT EFFICIENCY, %
0.539 ISRT) + 47.0
r = 0.86
10
20
30
40
SRT, days
Observed relationship between SRT and removal of
volatile solids.
87
-------
5
O
2
LU
CC
40
30
20
10
0
TREATMENT EFFICIENCY, % ' =
0.379 ISRT) + 27.3
r= 0.68
I
10 20 30
SRT, days
40
Figure 4.12. Observed relationship between SRT and removal of COD.
70
60
50
$5
J 40
§
9 30
LJ
CC
20
10
TREATMENT EFFICIENCY, %
0.452 (SRT) + 38.0
r = 0.74
10 20 30
SRT, days
40
Figure 4.13.
Observed relationship between SRT and removal of
organic nitrogen.
-------
Removal of Total Solids, % = 0.379 (SRT) + 27.3 (4.20)
Removal of Volatile Solids, % = 0.452 (SRT) + 38.0 (4.21)
Removal of COD, % = 0.294 (SRT) + 25.2 (4.22)
Removal of Organic Nitrogen, % = 0.539 (SRT) + 47.0 (4.23)
These four equations provide the basis for a process design approach which
with information on the raw waste characteristics and a SRT predicts both
carbonaceous and nitrogenous oxygen demand as well as effluent characteristics.
These equations also can be used to determine the required SRT to obtain a
specific effluent characteristic and to quantify other characteristics. While
not entirely satisfactory from a theoretical standpoint, these linear rela-
tionships in combination with delineation of the practical limits of biode-
gradability appear to provide practical design tools for these systems.
However, it should be recognized that the validity of Equations 4.20 through
4.23 is limited to SRT values between 10 and 36 days.
Nitrification is not a necessary prerequisite for the successful operation of
aeration systems for poultry wastes. It has been demonstrated that odor
control, stabilization of carbonaceous compounds, and nitrogen removal can be
achieved in the absence of nitrifying processes (2). The method of nitrogen
removal was ammonia stripping. Unless limited by available dissolved oxygen,
nitrification can be expected to occur to some degree in any aeration system.
Intentional introduction of nitrifying organisms into these systems is not
necessary.
While not a requirement as part of the aerobic waste stabilization process,
nitrification may be desirable in certain situations for the control of the
odor of ammonia and/or other reasons. In these instances, knowledge of the
kinetic relationships describing the two steps of the nitrification process
is necessary. Both Nitrosomonas and Nitrobacter have lower growth rates as
compared to heterotrophic microorganisms which utilize carbonaceous compounds.
Therefore, in situations where nitrification is desired, the selection of a
design value for the SRT should be based on the growth kinetics for nitrifying
organisms.
The substrate limited growth relationship has been used to describe the nitri-
fication process. Based upon this kinetic relationship, the minimum biological
solids retention time (0m) necessary to maintain process stability has been
defined as (14): c
6cm = (Yk - b)"1 (4.24)
89
-------
where: Y = growth yield coefficient, mass/mass
k = maximum rate of substrate utilization per unit weight
of microorganisms, time~l
b = microorganism decay coefficient, time
Values for kinetic coefficients for both ammonia and nitrite oxidation as well
as calculated values for e m at 20°C are presented in Table 4.3.
\*
TABLE 4.3. KINETIC COEFFICIENTS FOR BIOLOGICAL NITRIFICATION (32)
Process Y, mg/mg N b, days" k, mg N/mg-day
NH.-N
4.
0.29 0.05 1.8
Oxidation
N00-N
0.084 0.05 4.7
Oxidation
m
QC ,days
at 20°C
2.1
2.9
The e values of 2.1 and 2.9 days for ammonia and nitrite oxidation at 20°C
compare favorably with the observed value for e of 2 days for nitrification
in aerated poultry wastes (33).
Where system temperatures of less than 20°C are anticipated, e m values will
be greater than those at 20°C. Specific values can be calculated by first
correcting the maximum rate of substrate utilization coefficient, k, for
change in temperature and then using Equation 4.24. A modified form of the
van't Hoff - Arrhenius relationship, Equation 4.25, will provide a reasonable
estimate of the effect of temperature on k.
kT = kT . e(T2 - Tl) (4.25)
where: e = 1.106
T = temperature, °K
The value of 1.106 is that reported for nitrification in the temperature ranqe
of 5-20°C (34).
90
-------
The substrate removal relationships (Equations 4.20 through 4.23) provide the
basis for a process design approach for poultry waste aeration systems where
SRT is an independent design and operating parameter. However, in situations
where nitrification is a design objective, minimum design SRT values may be
limited by the values of e necessary to maintain nitrification process
stability.
4.5.3 Oxygen Transfer
As previously discussed, a and g (Equation 4.15) under process conditions are
functions of mixed liquor characteristics. In aerated poultry slurries a
values have been related to effective viscosity and to mixed liquor total
solids concentrations. The relationship between a and effective viscosity
reported for aerated poultry manure is presented in Figure 4.14. While relating
a to viscosity represents a sound analytical approach, utilization of this
information is cumbersome due to the difficulties of measuring viscosity of the
mixed liquor. Knowledge of the relationship between a and mixed liquor total
solids (MLTS) concentrations appears to be of greater practical value. MLTS
and viscosity in the mixed liquor are interrelated since the viscosity increases
as the MLTS increases. Research results (1, 35) indicate that a has an average
value of about one at MLTS concentrations of less than 20,000 mg/Ł. As MLTS
concentrations increase beyond that point, a values decrease to 0.4 at 55,000
mg/Ł. The relationship between a and MLTS concentration is presented in
Figure 4.15. Analysis of the data of Hashimoto and Chen (36) relating a to
MLTS concentrations produced a similar relationship. In order to facilitate
inclusion of the concept of a into process design, the mathematical relation-
ships noted in Figure 4.16 will be used to estimate a values. These
relationships were developed from the data presented in Figure 4.15.
In aerated poultry manure slurries, 3 has been reported to be independent of
total solids concentrations ranging from 1 to 6 percent (36). The average
value of 3 for 50 observations was reported to be 0.97 with a + 0.05
standard deviation.
It should be recognized that the quantity of oxygen actually transferred by an
aeration unit (Equation 4.15) is a function of the dissolved oxygen deficit,
C - C, . As the dissolved oxygen deficit increases, the mass of oxygen trans-
ferred per unit time also increases. Since energy consumption by the aeration
unit is fixed by physical constraints, the presence of high residual dissolved
oxygen concentrations in the mixed liquor, C[_, reduces the oxygen transfer
efficiency, i.e., the mass of oxygen per unit energy consumed. This results
in increased operating costs. Thus design values for C[_ should be no greater
than 1 to 2 mg/z for nitrifying systems (16). Lower values of Ci have been
demonstrated to be satisfactory for odor control where nitrification is not
desired (2).
4.6 Aeration System Process Design
An oxidation ditch or any other type of aeration system for poultry wastes can
be designed and operated either as a continuously loaded batch reactor or as
a continuous flow reactor. With the continuously loaded batch method, the
ditch would be emptied periodically, refilled with tapwater, and the system
restarted. This mode of operation has advantages in simplicity of operation
91
-------
UJ
ID
_J
<
I
3.0
2.0
1.5
1.0
.8
.6
.4
.3
.2
-.67
I I I I I I I II II I
.03 .05 .10 .2 .3 A .6 .8 1.0
jUe, POISE
2.0 3.0
Figure 4.14, Effect of effective viscosity (yg) on relative oxygen
transfer rate (a) (36).
92
-------
I
Q_
1.2
1.0
.8
.6
.4
0
•••
• **,
0
10
20
30
40
50
MIXED LIQUOR TOTAL SOLIDS CONCENTRATION, gms/*
Figure 4.15. Relationship between a and mixed liquor total solids
concentration in aerated poultry wastes (35).
93
-------
<Ł>
1.4
1.2
1.0
.8
.6
.4
0
0
a = 1.36 - .17 MLTS
a =0.4
10
20
30
40
50
60
70
MIXED LIQUOR TOTAL SOLIDS CONCENTRATION, gm/X
Figure 4.16. Effect of MLTS concentration on a in aerated poultry wastes (37)
-------
and combines storage with stabilization. A major liability, however, is a low
overall oxygenation efficiency. As the system mixed liquor total solids
(MLTS) concentration increases with time, the value of a and thus oxygen
transfer decreases (Figure 4.16 and Equation 4.15).
An alternative to the batch approach is a continuous flow process with control
of MLTS concentration via continuous residual solids removal. This provides
the opportunity to maximize oxygenation efficiency by maintenance of low
MLTS concentrations. With this type of systems management, solids retention
time (SRT) is a design and operating parameter allowing flexibility in match-
ing the degree of waste stabilization with overall waste management objectives.
The process designs of both batch and continuous flow aeration systems for
poultry wastes are based on the same fundamental concepts and relationships
that have been previously discussed. However, design parameters such as SRT
and MLTS concentrations which are independent variables in a continuous flow
system are dependent variables in a batch system. Therefore, the design
procedures for each system differ. The objective of this section is to
present, by example, design methodology for each type of system. In order to
facilitate presentation of design methodology, the relevant mathematical
relationships will be summarized and values of constants are raw waste charac-
teristics to be used will be presented.
4.6.1 Summary of Process Design Relationships, Kinetic Constants, and Raw
Waste Characteristics
The underlying equation for the process design of aeration systems for
poultry wastes is the empirical relationship between removal efficiency and
SRT, Equation 4.19.
Removal Efficiency, % - A(SRT) + B (4.19)
Values for the constants A and B for each parameter discussed previously in
Section 4.5.2 are summarized in Table 4.4. Also included in this table are
values defining the refractory fraction, R, for each parameter originally
presented in Section 4.5.1.
Utilizing the results from Equation 4.19, the residual quantities for each
parameter can be calculated using the following relationship:
S-j, gm/bird-day = [S , gm/bird-day] x
[Removal Efficiency, %/100] ^
where: S = the quantity of any parameter as raw waste, gm/bird-day
S-, = the quantity of the same parameter following stabilization,
gm/bird-day
95
-------
TABLE 4.4. FIXED CONSTANT VALUES FOR SUBSTRATE REMOVAL
RELATIONSHIPS FOR POULTRY WASTES
Parameter
Total Solids
Volatile Solids
Chemical Oxygen Demand
Organic Nitrogen
Fixed
A
0.379
0.452
0.294
0.539
Constant
B
27.3
38.0
25.2
47.0
Values
R
0.55
0.43
0.60
0.31
It should be noted that be definition, S, cannot be less than the refractory
fraction, R, for any characteristic.
The procedure for estimation of carbonaceous and nitrogenous oxygen demand
is based on the relationships presented in Equations 4.10 and 4.11. The
modified form of these equations for design use are as follows:
Carbonaceous oxygen demand, gm O^/hr = (4.27)
[(SQ, gm COD/bird-day - S], gm COD/
bird-day)(Number of birds)]/24 hour/day
Nitrogenous oxygen demand, gm 02/hr = (4.28)
[(SQ, gm ON/bird-day - S], gm ON/
bird-day)(4.57)(Number of birds)]/24 hours/day
The total microbial oxygen demand is simply the sum of the carbonaceous and
nitrogenous oxygen demands:
Total oxygen demand = Carbonaceous oxygen demand + (4.29)
Nitrogenous oxygen demand
As discussed in Section 4.5.3, the ratio of the value of the oxygen transfer
coefficient, KLa, in tapwater to that under process conditions, a, in aerated
poultry wastes decreases as MLTS concentrations increase. Thus, the oxygenation
96
-------
capacity of an aeration unit required to meet a constant microbial oxygen
demand increases as MLTS concentration increases (Equation 4.15). The
mathematical relationships which define a in relation to MLTS concentrations
(Figure 4.17) are:
For MLTS _< 20 gm/fc, a = 1 (4.30)
For MLTS > 20 gm/* and < 55 p/*, (4.31)
a = 1.36 - .017 MLTS, gm/Ł
For MLTS >_ 55 gm fa, a = 0.4 (4.32)
The required oxygen capacity at zero mixed liquor residual dissolved oxygen
concentration can be determined by the following relationship:
Oxygenation capacity, gm 02/hr = (Oxygen demand, gm/hr) /a (4.33)
The subsequent examples of design methodology will utilize the raw manure
characteristics presented in the following table. For procedures to estimate
raw waste characteristics for specific situations, the reader is referred to
Chapter 2.
TABLE 4.5. RAW WASTE CHARACTERISTICS USED FOR DESIGN EXAMPLES
Production
Parameter gm /bird-day
Total Solids 32.6
Volatile Solids 25.1
Chemical Oxygen Demand 28.0
Organic Nitrogen 1.94
97
-------
4.6.2 Batch System Process Design Methodology
The design of a continuously loaded, batch aeration system involves two
independent process design variables. They are system volume per bird and
cumulative time of operation for each batch cycle. For this mode of operation,
the average solids retention time (SRT) is:
Average SRT = cumulative time of operation ^ 2 (4.35)
Thus, SRT is a dependent variable which continually increases over the
operating period for the batch unit. As the time of operation and therefore
SRT increases, the treatment efficiency for each waste characterization
parameter also increases until the limits of the biodegradable fraction are
reached at which point treatment efficiency becomes constant. This two step
phenomena is reflected in the rate of microbial oxygen demand which increases
until maximum treatment efficiency is attained and then becomes constant.
The increase in MLTS concentration as well as concentrations of other
parameters follow a similar pattern. At levels below maximum treatment
efficiency, the accumulation of total solids (TS), volatile solids (VS),
chemical oxygen demand (COD), and organic nitrogen (ON) consist of unstabilized,
biodegradable as well as refractory fractions. As maximum treatment efficiency
is reached, rates of accumulation decrease and then become constant. Of parti-
cular interest are total solids due to the effect of increasing MLTS concen-
trations on a (Equations 4.30 through 4.32) and ultimately on required oxygenation
capacity to meet a specific microbial oxygen demand (Equation 4.34).
The following is a summary of the steps in the process design of a continuously
loaded, batch aeration system for poultry manure.
A. Measure manure production and determine characteristics or
estimate these values using Equations 2.1 and 2.2 and the
poultry waste characteristics presented in Table 2.4 (Chapter 2).
B. Select design values for system volume per bird and a time
period in the batch operating cycle.
C. Calculate the average SRT using Equation 4.34.
D. Determine removal efficiencies for total solids (TS), volatile
solids (VS), chemical oxygen demand (COD), and organic nitrogen
(ON) using Equation 4,19 and the appropriate constants from
Table 4.4.
E. Compute the residual quantities of each waste characterization
parameter using Equation 4.26 with the previously calculated
treatment efficiencies and the established raw waste characteristics.
F. Determine carbonaceous, nitrogenous, and total oxygen demands
from Equations 4.27 through 4.29.
98
-------
G. Calculate the mixed liquor concentrations for each parameter
using the following relationship.
Mixed liquor concentration, gm/a =
[(S-,, gm/bird-day)(Time of operation, days)] *
(volume/bird, Ł/bird)
H. Identify the value for a corresponding to the MLTS concentra-
tion using the appropriate relationship (Equations 4.30
through 4.32).
I. Compute aeration capacities required to meet carbonaceous,
nitrogenous, and total oxygen demands using Equation 4.33.
As an illustration of batch aeration design process, the following design
example will outline required steps for the process design of a system for
30,000 birds.
A. For this example, raw waste characteristics presented in Table
4.5 will be used.
B. Design system volume is 20 &/bird and the design time period per
batch cycle is 30 days.
C. Average SRT (Equation 4.34) is
Average SRT - 30 days * 2 = 15 days
D- For a 15 day SRT, removal efficiencies for each waste characteri-
zation parameter (Equation 4.19 and Table 4.4) are:
- TS removal efficiency, % = 0.379 (15 days) + 27.3 = 33.0%
- VS removal efficiency, % = 0.452 (15 days) + 38.0 = 44.8%
- COD removal efficiency, % = 0.294 (15 days) + 25.2 = 29.6%
- ON removal efficiency, % = 0.539 (15 days) + 47.0 - 55.1%
E. From Equation 4.26, the calculated treatment efficiencies, and
the raw wastes characteristics (S ) (Table 4.5), the residual
quantities for each waste characterization parameter are:
- S-,, gm TS/bird-day = 32.6 gm TS/bird-day x
[1 - (33.0/100)] = 21.8 gm TS/bird-day
- S-j, gm VS/bird-day - 25.1 gm VS/bird-day x
[1 - (44.8/100)] = 13.8 gm TS/bird-day
- S-], gm COD/bird-day = 28.0 gm COD/bird-day x
[1 - (29.6/100)] = 19.7 gm COD/bird-day
99
-------
- Sr gm ON/bird-day = 1.94 gin ON/bird-day x
[1 - (55.1/100)] = 0.87 gm ON/bird-day
F. Carbonaceous, nitrogenous, and total oxygen demands (Equations
4.27 through 4.29) are:
- Carbonaceous oxygen demand, gm 02/hr = [(28.0 gm COD/bird-day
19.7 gm COD/bird-day)(30,000 birds)] *
24 hr/day = 10,375 gms 02/hr or 10.4 kg 02/hr
- Nitrogenous oxygen demand, gm 02/hr - (1.94 gm ON/bird-day -
0.87 gm ON/bird-day)(4.57) (30,000 birds)] *
24 hr/day = 6,112 gm 02/hr or 6.1 kg 02/hr
- Total oxygen demand, kg 02/hr = 10.4 + 6.1 = 16.5 kg 02/hr
G. Mixed liquor concentrations at day 30 of operation from the
calculated values for residual quantities will be:
- MLTS, gm/i = [(21.8 gm TS/bird-day)(30 days)] *
20 fc/bird = 32.7 gm TS/Ł
- MLVS, gm/A = [(13.8 gm VS/bird-day)(30 days)] *
20 A/bird = 20.7 gm MS/a
- MLCOD, gm/Ł = [(19.7 gm COD/bird-day)(30 days)] *
20 2./bird = 29.5 gm COD/Ł
- MLON, gm/A = [(0.87 gm ON/bird-day)(30 days)] *
20 Vbird = 1.30 gm ON/Ł
H. For a MLTS concentration of 32.7 gm/&, the predicted value
of a (Equation 4.31) is:
a = 1.36 - 0.17(32.7) = 0.80
I, Required aeration capacities on day 30 of operation
(Equation 4.33) are:
- Carbonaceous oxygenation capacity, kg 02/hr = 10.4 kg 0?/hr *
0.80 - 13 kg 02/hr
- Nitrogenous oxygenation capacity, kg 02/hr = 6.1 kg 0?/hr *
0.80 - 7.6 kg 02/hr
- Total oxygenation capacity, kg 0?/hr = 16.5 kg 0?/hr ^~
0.80 = 20.6 kg 02/hr
100
-------
The same procedure was used to determine treatment efficiency, oxygen demand,
mixed liquor characteristics, and oxygenation requirements at 60 days. A
comparison between 30 and 60 days is presented in Table 4.6.
TABLE 4.6. COMPARISON OF PROCESS DESIGN COMPUTATIONS FOR 30 AND
60 DAYS OF SYSTEM OPERATION
Parameter 30 Days 60 Days
Treatment Removal Efficiency, %
Total Solids 33.0 38.7
Volatile Solids 44.8 51,6
Chemical Oxygen Demand 29.6 34.0
Organic Nitrogen 55.1 63.2
Residual Quantities, gm/bird-day
Total Solids 21.8 20.0
Volatile Solids 13.8 12.1
Chemical Oxygen Demand 19.7 18.5
Organic Nitrogen 0.87 0.71
Microbial Oxygen Demand, kg Oo/hr
Carbonaceous 10.4 11.9
Nitrogenous 6.1 7.0
Total 16.5 18.9
Mi xed L i quor Concen tr a t i on s , gm/ _&
Total Solids 32.7 60.0
Volatile Solids 20.7 36.3
Chemical Oxygen Demand 29.5 55.5
Organic Nitrogen 1.30 2.13
Alpha (a) 0.80 0.40
Required Oxygenation Capacity, kg
Carbonaceous 13.0 29.8
Nitrogenous 7.6 17.5
Total 20.6 47.3
101
-------
As shown, slight increases in treatment efficiency occur with comparable in-
creases in microbial oxygen demands between 30 and 60 days. Residual quantities
of each parameter accumulating in the system per bird-day decrease slightly.
However, a large increase in mixed liquor concentrations occurs. The increase
in MLTS concentration results in a 50% decrease in the value of a resulting
in a sizable increase in the required oxygenation capacity to satisfy the
microbial oxygen demand. If a design objective were to provide 60 days of
storage, the aeration equipment would have to be sized to meet the final
oxygenation requirements. However, over aeration would occur until the MLTS
concentration reached 55 gms/Ł (a = 0.4, Equation 4.32), resulting in excessive
operating costs. Procedures to optimize design will be considered in detail
in the next chapter.
4.6.3 Continuous Flow System Process Design Methodology
The design of a continuous flow aeration system differs from a batch system
in that SRT and MLTS concentration are independent design variables. In
these systems, the desired level of treatment efficiency consistent with
overall waste management objectives can be achieved by selecting the appro-
priate SRT value. At constant levels of treatment efficiencies for COD and
organic nitrogen, microbial oxygen demand remains constant. In that SRT is
held constant by removal of excess solids, MLTS concentration is also constant
as is a and required oxygenation capacity. The desired value for MLTS concen-
tration determines the system volume with volume decreasing as MLTS values
increase.
The following is a summary of the steps in the process design of a continuous
flow aeration system for poultry wastes.
A. Measure manure production and determine characteristics or
estimate these values using Equations 2.1 and 2.2 and the poultry
waste characteristics presented in Table 2.4 (Chapter 2).
B. Select design values for SRT and MLTS concentration.
C. Determine removal efficiencies for total solids (TS), volatile
solids (VS), chemical oxygen demand (COD), and organic nitrogen
(ON) using Equation 4.19 and the appropriate constants from
Table 4.4.
D. Compute the residual quantities of each waste characterization
parameter using Equation 4.26 with the previously calculated
treatment efficiencies and the established raw waste characteristics.
E. Determine carbonaceous, nitrogenous, and total oxygen demands from
Equations 4.27 through 4.29.
F. Identify the value for a corresponding to the design value for
MLTS concentration using the appropriate relationship (Equations
4.30 through 4.32).
102
-------
G. Compute aeration capacities required to meet carbonaceous,
nitrogenous, and total oxygen demands using Equation 4.33 =
H. Calculate mixed liquor concentrations of VS, COD, and ON
from the previously calculated residual quantities.
I. Determine system volume, the quantity of residual solids to
be removed to maintain an equilibrium SRT and MLTS concentration,
and the volume of mixed liquor to be withdrawn to achieve the
desired residual solids removal using the following relationships:
- System volume, & = [S-, , gm TS/bird-day)(No. of birds)
(SRT, days) * (MLTS concentration, gmA )
- Residual solids removal, gm/day =
(S, , gm TS/bird-day) (No. of birds)
- Flow rate for residual solids removal, Ł/day =
(gm residual TS/day) * (MLTS concentration,
As an illustration of continuous flow aeration design process, the following
design example will outline the required steps for the process design of a
system for 30,000 birds.
A. For this example, raw waste characteristics presented in
Table 4.5 will be used.
B. The design value for SRT is 20 days and the design MLTS
concentration is 10 gm/ a.
C. For a 20 day SRT, removal efficiencies for each waste characteri-
zation parameter (Equation 4.19 and Table 4.4) are:
- TS treatment efficiency, % = 0.379(10) + 27.3 = 31.1%
- VS treatment efficiency, % = 0.452(10) + 38.0 = 42.5%
- COD treatment efficiency, % = 0.294(10) + 25.2 = 28.1%
- ON treatment efficiency, % = 0.539(10) + 47.0 = 52.4%
D. From Equation 4.26, the calculated treatment efficiencies and
the raw waste characteristics (S ) (Table 4.5), the residual
quantities for each waste characterization parameter are:
- Sp gm TS/bird-day = 32.6 gm TS/bird-day x
D - (31.1/100)] = 22.5 gm TS/bird-day
- S1§ gm VS/bird-day = 25.1 gm VS/bird-day x
[1 - (42.5/100)] = 14.4 gm VS/bird-day
- 5^ gm COD/bird-day = 28.0 gm COD/bird-day x
[1 - (28.1/100)] = 20.1 gm COD/bird-day
103
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- S,, gm ON/bird-day = 1.94 gm ON/bird-day x
[1 - (52.4/100)] = 0.92 gm ON/bird-day
E. Carbonaceous, nitrogenous, and total oxygen demands
(Equations 4.27 through 4.39) are:
- Carbonaceous oxygen demand, gm 02/hr = [(28.0 gm COD/bird-day -
20.1 gm COD/bird-day) (30,000 birds)] * 24 hr/day =
9875 gm 02/hr or 9.9 kg 02/hr
- Nitrogenous oxygen demand, gm 02/hr = [(1.94 gm ON/bird-day -
0.92 gm ON/bird-day) (4.57) (30,000 birds] * 24 hr/day -
5827 gm 02/hr or 5.8 kg 02/hr
- Total oxygen demand, kg 02/hr = 9.9 + 5.8 = 15.7 kg 02/hr
F. For a MLTS concentration of 10 gm/& , the predicted value of a
(Equation 4.30) is:
a = 1.0
6. Required aeration capacities will be equal to the respective
carbonaceous, nitrogenous, and total oxygen demands at a zero
mixed liquor dissolved oxygen concentration since a has a value
of unity (Equation 4.33).
H. The mixed liquor concentrations of VS, COD, and ON for a MLTS
concentration of 10 gm/Ł will be:
- (X gm MLVS/Ł) x (27.5 gm TS/bird-day) = (14.4 gm VS/bird-day) x
(10 gm MLTS/Ji) = 6.4 gm MLVS/JL
- (X gm MLCOD/Ł) x (22.5 gm TS/bird-day) = (20.1 gm COD/bird-day) x
(10 gm MLTS/2.) = 8-9 9m ML.COD/S,
- (X gm MLON/&) x (22.5 gm TS/bird-day) = (0.92 gm ON/bird-day) x
(10 gm MLTS/Ł) - 0.41 gm MLON/4
I. - System volume, l = [(22.5 gm TS/bird-day) (30,000 birds)
(20 days)] * 10 gm TS/n = 1.35 x 106 or 4.5 Ł/bird
- Residual solids removal, gm TS/day = (22.5 gm TS/bird-day)
(30,000 birds) - 675,000 gm or 6.75 kg TS/day
- Flow rate for residual solids removal, Ł/day =
(675,000 gm TS/day) * (10 gm IS/A) = 67,500 Ł of
mixed liquor/day
104
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The same procedure was used to develop a process design at a MLTS concentra-
tion of 35 gm/a. Since SRT remains constant, treatment efficiencies,
residual quantities, and microbial oxygen demand remain constant. However,
a, required oxygenation capacity, system volume, and volume of mixed liquor
removal for residual solids removal do change. A comparison of these values
for MLTS concentrations of 10 and 35 gm/Ł is presented in Table 4.7.
TABLE 4.7. COMPARISON OF PROCESS DESIGN COMPUTATIONS FOR M.TS
CONCENTRATIONS OF 10 AND 35 GM/Ł
Parameter 10 gm/ a 35 gm/Ł
Alpha (a) 1.0 0.76
Required Oxygenation Capacity,
kg
Carbonaceous 9.9 13.0
Nitrogenous 5.8 7.6
Total 15.7 20.6
System Volume, i/bird 45.0 12.8
Flow Rate for Residual Solids
Removal, I/day _ 67,500 19,286
As can be seen in Table 4.7, an increase in the design MLTS concentration
increases required oxygenation capacity. However, system volume and the
required flow rate for residual solids removal decrease significantly. Hence
a trade-off exists between aeration costs and ultimate disposal costs. A
more detailed examination of the effects of variation of MLTS concentrations
and SRT will be discussed in the next chapter.
4.7 Physical Design Considerations
Presentation of details of the structural aspects of oxidation ditch design
is beyond the scope of this manual. Assistance in this area is available
from sources such as the Cooperative Extension Service. However, a discussion
of several aspects of physical design which have a direct bearing on process
performance appears appropriate. Included will be discussion of:
A. Aeration unit evaluation and selection;
B. Mixing requirements and oxidation ditch channel design;
105
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C. Liquid-solids separation;
D. Potential problems and miscellaneous design details.
4.7.1 Aeration Unit Selection
One of the most important and complex steps in the design of any aerobic
waste treatment system is aeration unit selection. Since the energy required
to drive the aeration unit will be the major operating cost, the efficiency
of the aeration unit, i.e., mass of oxygen transferred per unit energy consumed,
is of considerable importance. Aeration units for oxidation ditches are
available from several manufacturers. Due to differences in design,
performance characteristics vary among units. Therefore, it is important to
understand how aeration units are evaluated and rated.
The oxygen transfer characteristics of an aeration unit in tapwater serve
as the standard method for equipment characterization. The technique most
commonly used to evaluate oxygen transfer in tapwater is the non-steady state
chemical method (38). This test involves the use of sodium sulfite (NagSOg)
in the presence of a catalyst, cobalt chloride (CoClp) to deplete the
dissolved oxygen of the water in the test basin.
Following the commencement of aeration, the increase in dissolved oxygen
concentration with time is determined. These data are then used to determine
the oxygen transfer coefficient, K,a, utilizing Equation 4.14.
HT = KLa
A semi-logrithmic plot of the dissolved oxygen deficit (C - C, ) versus time
should produce a straight line, the slope of which is K.a (Figure 4.17).
Since oxygen transfer varies with temperature, experimental values of K.a are
normally corrected to 20°C using the following relationship:
KLa20°C = Q(T-20T (4'35)
where: KLa20°C = the Va1ue of Kla at 20°C
e = the temperature correction factor for the system
T = the water temperature, °C
The value most commonly used for the temperature correction factor (0) is
1.024 (16). The experimentally determined value of K, a is then used in the
calculation of the oxygenation capacity of the aeration unit tested
(Equation 4.15).
106
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10
8
7
O
I
co
O
O
Li_
UJ
Q
UJ
O
X
O
Q
UJ
co 0.9
CO
5 0.8
0.7
0.61
0.5l
SLOPE = KLa
1 1 I
L
2 4 68 10 12 14 16 20 22
TIME FROM START OF AERATION, minutes
24
Figure 4.17. Determination of KLa in tap water.
107
-------
N = aKLa200(, (3CS - CL) (V) (4.15)
For tapwater, both a and 3 have values of unity.
Normally, energy consumption is measured during oxygen transfer studies thus
permitting determination of the overall oxygen transfer efficiency, i.e.,
kg CL per gross kw-hr (Ib 00 per hp-hr). However, some manufacturers express
oxygen transfer efficiency Hn terms of mass of oxygen transferred per unit
power required by the aeration unit, i.e., kg CL per net kw (Ib CL per brake
hp). This practice excludes motor efficiency and results in a higher value
for oxygen transfer efficiency. Therefore, care should be exercised when
compraring performance characteristics to be sure a common basis is being
used.
Once the details of process design are complete and an aeration unit supplier
has been chosen, the selection of a properly sized aeration unit should be
the joint responsibility of the designer and the equipment manufacturer. The
designers role should be to specify both the required rate of oxygen transfer
and ditch velocity. This entails identification of anticipated operating
conditions such as residual dissolved oxygen concentration, a and 3 factors,
and temperature. Information concerning design mixed liquor velocity, ditch
geometry, and maximum expected mixed liquor total solids (MLTS) concentration
should also be included.
Once performance specifications and operating conditions are delineated, the
equipment manufacturer should determine equipment requirements. This appears
to be logical in that the manufacturer is most familiar with his equipment by
virtue of testing and experience.
Designers should be aware that values for both the oxygen transfer coefficient,
K, a, and pumping capacity determined under test conditions are a function not
only of the aeration unit but also the test basin. Therefore, performance may
vary. For these reasons, the use of performance specifications have been
suggested to insure that aeration equipment will perform as expected (39). In
the field of domestic waste treatment, it has been reported that in 16 dif-
ferent aeration tests less than 50 percent of the aeration equipment meet
specifications (40).
Several methods of performance testing are available. These include non-
steady chemical test, steady state microbial method, and the non-steady state
microbial method. The non-steady state chemical method has been described
earlier in this section. Descriptions of the steady and non-steady state
microbial methods are available (16). The practice of performance testing
should benefit not only the owner and designer but also the manufacturer
by increasing his knowledge of equipment performance under a broad range of
conditions.
108
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4.7.2 Mixing Requirements and Oxidation Ditch Channel Design
The accumulation of settled solids in oxidation ditch channels is an often
cited problem in discussions of oxidation ditches stabilizing animal wastes
(2, 26, 31, 41, 42, 43). However, this problem has received little attention.
An early misconception concerning sediment accumulation in these systems was
that an equilibrium would be reached. Results of a full scale demonstration
study of oxidation ditch stabilization of poultry wastes (2) has shown that
the above assumption is untrue. In that study, initial mixed liquor velocity
was not adequate to prevent settling. It was observed that sediment
accumulation is accelerated resulting in a further decrease in velocity. This
process was observed to continue until the mixed liquor velocity approached
zero which occurred on several occasions.
This phenomenon can be understood by considering circulation in an oxidation
ditch in terms of the Manning uniform equation for open channel flow
(Equation 4.36).
V . Rs (4.36)
where: V = velocity, length/time
N = coefficient of roughness, dimensionless
R = hydraulic radius (cross-sectional area divided by the
wetted perimeter), length
S = slope of the energy grade line, length/length
Assuming a constant energy input and therefore a constant equivalent to the
slope of the energy grade line, this equation predicts that velocity will
decrease as the coefficient of roughness increases and/or as the hydraulic
radius decreases. Sediment accumulations cause both to occur.
As discussed by Chow (44), several factors affect the coefficient of roughness.
Included are surface roughness and channel irregularity. Surface roughness
is a function of the shape and size of the grains of the material forming the
wetted perimeter. A significant difference should not exist between concrete
and poultry manure solids. The suggested value of N for a concrete-lined
channel in good condition is 0.014 (45). However, sediment accumulations can
significantly affect channel irregularity (Figure 18). Irregularity can
increase the value of N to as much as 0.021 (44)1
Decreasing mixed liquor velocity due to sediment accumulation not only
accelerates settling but also decreases mixing and oxygen transport. Thus,
sediment accumulations can adversely affect the biological waste stabilization
process possibly resulting in process failure. Therefore, the mixed liquor
design velocity for an oxidation ditch should equal or exceed the scour
velocity necessary to keep the heaviest manure particles in suspension.
109
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0 20 40 60 80
DISTANCE FROM AERATION UNIT,
100
m
"0 20 40 60 80 100
DISTANCE FROM AERATION UNIT, m
Figure 4.18.
Observed patterns of sediment accumulation in oxidation
ditches receiving poultry wastes (2).
110
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The velocity necessary to keep the heaviest poultry manure particles in
suspension can be calculated using the following relationship:
where: VH = horizontal velocity that will produce scour, length/time
s - specific gravity of particles, mass/volume
d = diameter of particles, length
k = constant dependent on the type of material being
scoured, dimensionless
f = Darey-Weisbach friction factor, dimensionless
o
g = acceleration due to, gravity, length/time
Using the following values (Table 4.8), the scour velocity for the heaviest
particles in poultry manure was calculated to be 0.53 m/sec (1.74 ft/sec).
TABLE 4.8. VALUES USED TO ESTIMATE THE SCOUR VELOCITY
FOR POULTRY MANURE
s = 2 gm/cm3 (46)*
d = 1.19 mm, maximum (46)
k = 0.06 (47)
f = 0.02 (47)
* Numbers in parentheses refer to data sources.
The energy required to maintain the desired velocity in an oxidation ditch
can be equated to the energy loss due to friction. Wong-Chong, et al. (48)
have suggested the use of the Fanning (Darcy) equation (Equation 4.38) to
estimate ffictional energy losses in these systems.
„ 2LV2f (4.38)
Hf s -
111
-------
where: Hf = energy loss due to friction, length
DM = hydraulic diameter, length
n
f = Fanning's friction factor, dimensionless
?
g = acceleration due to gravity, length/time
L = total straight length of open channel, length
V = flow velocity in the channel, length/time
While this approach is valid for estimating frictional losses in linear
channel sections (49), a method to calculate these losses in semi-circular
channel sections is not possible. However, general relationships affecting
friction losses in these channels are known. Chow (44) states that the
coefficient of curve resistance, f , is a function of several factors which
are:
R = Reynolds number
y/b = ratio of liquid depth to channel width
a/1800 = ratio of angle of curvature to 180°
r /b = ratio of radius of curvature to channel width
General characteristics of the relationship between each of these factors
and f have been presented by Shukry (50) based upon experimental studies
involving water. A summary of these relationships are as follows:
A. The coefficient, f , decreases as the Reynolds number increases
up to the value of R = 3x10 . Beyond that point, f increased.
B. The coefficient fc decreases as the ratio of liquid depth to
channel width (y/b) increases.
C. The coefficient f decreases as the ratio of the radius of
curvature to widtn (r /b) increases.
D. The coefficient f increases as the ratio of angle of curvature
to 180° (a/1800) increases.
The effect of f on energy loss due to curve resistance in terms of velocity
head can be expressed as follows:
hf = fc (4'39)
112
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where: hf = velocity head loss, length
V = mean velocity in the section, length/time
2
g = acceleration due to gravity, length/time
At this time, the determination of the required energy input to maintain a
desired mixed liquor velocity remains an art rather than a science. However,
it is clear that a major fraction of the frictional energy losses in these
systems occurs in the semi-circular connecting channels. In a comparison of
two oxidation ditches differing significantly only in the radius of curvature
of the semi-circular sections, it was shown that mixed liquor velocity can be
increased without increasing energy input by increasing the r /b ratio (2).
In designing oxidation ditch channels, it should be recognized that the current
practice of adapting channel geometry to animal locations increases energy
requirements for mixing. Particularly in the poultry industry, the above
practice results in semi-circular channels with small radius of curvatures.
Also, most oxidation ditches for animal wastes are designed to operate with
shallow liquid depths thus having small ratios of liquid depth to channel
width.
An alternative is to design the ditch channel to minimize energy losses due
to friction and therefore energy requirements for mixing. However, this
approach will require large radii of curvature and possibly not having the
ditch channel directly below the animals. This eliminates the advantage of
direct deposition of the wastes into the treatment unit. Equipment such as
scrapers or flushing units will be required at least for a portion of the
wastes. It should be recognized that trade-offs exist. However, these
trade-offs can not be analyzed quantitatively at present. Thus, judgement
and experience must be relied upon for design decisions.
4.7.3 Liquid-Solids Separation
As noted earlier, the operation of an aeration system for poultry wastes as a
continuous flow process has several advantages. It permits operation at an
equilibrium mixed liquor total solids (MLTS) concentration of less than
20,000 mg/2, which results in maximum oxygen transfer efficiency. Of equal
importance is that the solids retention time (SRT) becomes a design and
operating parameter allowing flexibility in the desired degree of waste
stabilization.
In order to maintain an equilibrium MLTS concentration, continuous removal of
residual total solids is necessary. However, the volume of manure added per
day is not sufficient to create a significant overflow. Based upon the poultry
manure characteristics presented in Table 2.5 (Chapter 2), the volume of
manure produced by 30,000 birds is approximately 3700 Vday (980 gal/day).
For a continuous flow aeration system with an SRT of 20 days and a MLTS concen-
tration of 35 gm/Ł, 3700 Ł represents only one percent of the system volume
and 20 percent of the required flow rate for residual solids removal
(Table 4.7). These calculations assume no evaporation. Therefore, actual
percentages will be lower. Experience with pilot plant scale aeration units
113
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has shown that evaporation exceeds the volume of manure input for poultry
wastes. Therefore, it is necessary to create a flow for the removal of the
solids. Several approaches are available. One would be to continually add
tapwater to create a continuous overflow into a storage lagoon. However,
ultimate disposal requirements would increase due to the added water.
A second method would be to operate the system as a draw and fill reactor.
Some variations in SRT and MLTS concentrations would occur but ultimate
disposal requirements would be reduced. A third approach would be to utilize
a liquid-solid separation process and return the liquid to the system to
create flow. While this is the most complex alternative, it is the most
reasonable in terms of ultimate disposal if a reasonable degree of solids
thickening can be achieved.
Research concerning liquid-solids separation processes for poultry wastes
has been limited. Three processes; gravitational settling, screening, and
centrifugation; have been evaluated to varying degrees. It is the objective
of this section to present available information concerning these processes.
The use of gravitational settling for aerated poultry wastes has been
examined under full scale conditions (2). Performance was reported to be
less than satisfactory. This was attributed to the design approach which was
based on overflow rates for domestic activated sludge. Results of subsequent
laboratory studies has shown that the zone settling velocity (ZSV) of aerated
poultry manure decreases rapidly as MLTS concentrations approach 10,000 mg/a
(Figure 4.19) (51). Beyond 10,000 mg/Ł, zone settling velocities are minimal.
Using the clarification and thickening design approach presented by Lawrence
(52) which is based upon the batch flux concept (53), design surface area
requirements for clarification and thickening of aerated poultry wastes were
examined. The relationship between surface area required for clarification
(Figure 4.20) shows area requirements increase rapidly as MLTS concentrations
exceed 6000 mg/Ł. The relationship between surface area requirements for
thickening and total solids concentration in clarifier underflow (Figure 4.21)
suggests that 32,000 mg/Ł represents the practical upper limit for concentra-
tion of residual solids in aerated poultry wastes. Thus, the feasibility of
this approach appears to be questionable.
The use of centrifugation and screening has also been investigated but to a
more limited degree. Centrifuge test results (Table 4.9) indicated that this
process is capable of a high degree of solids removal from aerated poultry
wastes. Also, the centrifugation process produced a concentrated sludge which
can significantly reduce the volume of material requiring ultimate disposal in
comparison to direct disposal of mixed liquor. While these results suggest
that the process has significant potential, detailed information concerning
optimum methods of operation, costs and ease of operation are lacking, Thus,
comments on the feasibility of the process and a detailed discussion of design
factors are not possible at this time.
Results of screening tests indicated that this process has only limited
potential for liquid-solids separation of aerated poultry wastes (2). This
is due to particle size distribution. Results of 200 mesh screening tests
114
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180
160
140
120
O ,00
O
.c
UJ
UJ
O
80
60
40
20
0
0
Figure 4.19.
I
I
2000 4000 SOOO 8000 10000 12000
MIXED LIQUOR TOTAL SOLIDS
CONCENTRATION, mg/SL
Zone settling velocity versus total solids concentration
for aerated poultry wastes (51).
115
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2000
4000
6000
8000
10000
MIXED LIQUOR TOTAL SOLIDS
CONCENTRATION, mg/!
Figure 4.20. Dependence of clarifier surface area for clarification
on mixed liquor total solids concentration for aerated
poultry wastes (51).
116
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1200
1000 —
LL-.tr
.Q
08
o: Ł
(TO
-------
indicated that 60 to 80 percent of the suspended solids in aerated poultry
wastes were less than 0.074 mm in diameter. While the use of finer screens
250 and 325 mesh, improved solids removal, they required reduced flow rates
and decreased cake dry matter content. It was concluded that screening was
only practical for removal of coarse solids and would have to be used in
combination with another liquid-solids separation process for a continuous
flow system.
Recently, several commercial equipment manufacturers have introduced roller
presses for the separation and concentration of solids from animal wastes.
At present, performance of these units with aerated poultry waste remains to
be defined. Thus, the feasibility of these units is unclear. It is suggested
that designers investigate the availability of newly developed information
concerning these units before making design decisions concerning liquid-solids
separation.
4.7.4 Potential Problems and Miscellaneous Design Details
Foam is probably the most common problem encountered in the operation of
aeration systems for poultry and other animal manures. While a thin foam
layer is not atypical of a well operating aeration system, the presence of
an excessive quantity of foam is an indicator of a fundamental problem. There
appear to be several different reasons for foaming. The following is a
discussion of the various causes and solutions.
Foaming is a common occurrence during aeration system start-up. This is
apparently due to an imbalance in the food to microorganism ratio due to
an inadequate microbial populaton. If possible, the system should be seeded
with mixed liquor from another aeration system or from the previous batch if
a batch mode of operation is employed. An advantage of the continuous flow
mode of operation is that repeated start-up situations are avoided. Gradual
housing of hens where possible will also serve to reduce start-up foaming
problems.
Excessive foaming is typical of systems where the level of oxygen transfer
is inadequate to meet the exerted carbonaceous oxygen demand. This results
in the production of surface active metabolic end-products and is usually
accompanied by malodors. The solution to this type of foaming problem is
to increase aeration capacity or to reduce the mixed liquor total solids
concentration to increase oxygen transfer if possible.
Foaming problems have also been encountered in apparently well operating
systems. McKinney and Bella (54) have suggested that accumulations of
settled solids are responsible for foaming in these situations. The
maintenance of adequate mixed liquor surface velocities in oxidation ditches
is important in foam control in these systems. This provides a continuous
breakdown of any foam by the aeration unit. The absence of structures such
as overflow standpipes in the ditch channel which may hinder foam movement
is important. Feathers which may form large floating mats can also restrict
foam movement. Periodic removal of these feather accumulations may be
necessary.
118
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An often suggested strategy for foam control is the addition of vegetable
or petroleum oil. This practice is at best a short term solution which does
nothing to correct the fundamental problem. Moreover, the addition of
petroleum oil may significantly reduce the ratio of K.a in the mixed liquor
to K, a in tapwater, a , thus reducing oxygen transfer {Equation 4.15) (36).
Therefore, this practice can intensify problems of foam and odor where oxygen
transfer is inadequate. It is recommended that oil additions be only con-
sidered as a measure of last resort while more fundamental solutions are
applied.
An advantage of aeration as compared to drying systems for poultry wastes -
is that leakage from bird watering systems will not adversely affect process
performance. While it appears that a balance will exist between manure input
and evaporation permitting maintenance of a constant system volume, signifi-
cant watering system leakage will produce an overflow situation. The need
for a collection and storage basin as well as increased ultimate disposal
requirements will result.
Three types of watering systems are currently in use in the poultry industry.
They are nipple valves, cups, and troughs. Experience indicates that in
spite of manufacturer's claims, neither nipple valves nor cups will provide
a reliable leak-free watering system. While trough watering systems require
periodic cleaning, the potential for overflow is minimal. Therefore, it is
suggested that trough water systems be used with aeration systems for poultry
wastes.
Oxidation ditch aeration units, like other types of mechanical equipment,
require regular maintenance as well as occasional repairs. The most frequently
encountered mechanical problem with these units is bearing failure. Thus,
accessibility for maintenance and repairs should be considered when determining
the location of aeration units.
4.8 References
1. Loehr, R.C., D.F. Anderson, and A.C. Anthonisen. An Oxidation Ditch for
the Handling and Treatment of Poultry Wastes. In: Livestock Waste
Management and Pollution Abatement. ASAE. St. Joseph, Michigan. 1971.
p. 209-212.
2. Martin, J.H. and R.C. Loehr. Demonstration of Aeration Systems for Poultry
Wastes. Environmental Protection Technology Series Report No. EPA 666/2-76-
186. U.S. Environmental Protection Agency. Washington, D.C. 1976. 151 p.
3. Hashimoto, A.6. Aeration Under Caged Laying Hens. Transactions of the
ASAE. 15(6):1119-n23. ASAE. St. Joseph, Michigan. 1972.
4. Pajak, A.P. and R.C. Loehr. Treatment of Poultry Manure Wastewater Using
a Rotating Biological Contactor. Water Research. 10:399-406. London.
1976.
119
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5. Water Pollution Control Federation. Aeration in Wastewater Treatment--
Manual of Practice No. 5.. Washington, D.C. 1970. 96 p.
6. Pasveer, A. New Developments in the Application of Kessner Brushes
(Aeration Rotors) in the Activated-Sludge Treatment of Trade-Waste
Waters. Waste Treatment, P.C.G. Isaacs, ed., Pergamon Press, London.
1960. p. 126-155.
7. Newtson, K. Current Status of the Oxidation Ditch: Field Applications
and Field Results. In: Proceedings, 10th National Pork Industry Con-
ference. Lincoln, Nebraska. 1967.
8. Monod, J. The Growth of Bacterial Cultures. Annual Review of Micro-
biology. 3:371-394, 1949.
9. Fair, G.M. and J.C. Geyer. Elements of Water Supply and Waste-Water
Disposal. John Wiley and Sons, New York. 1958. p. 418-420.
10. Owens, J.D., M.R. Evans, F.E. Thuder, R. Hissett, and S. Baines. Aerobic
Treatment of Piggery Wastes. Water Research. 7:1745-1766, 1973.
11. McKinney, R.E. Mathematics of Complete-Mixing Activated Sludge. J.
Sanitary Engr. Div., ASCE. 88:87-113.
12. Goodman, B.L. and A.J. Englande, Jr. A Unified Model of the Activated
Sludge Process. J. Water Poll. Control Fed. 46:312-332, 1974.
13. Prakasam, T.B.S., R.C. Loehr, P.Y. Yang, T.W. Scott, and T.W. Bateman.
Design Parameters for Animal Waste Treatment Systems. Environmental
Protection Technology Series Report No. 660/2-74-063. U.S. Environmental
Protection Agency, Washington, D.C. 1974. 218 p.
14. Lawrence, A.W. and P.L. McCarty. Unified Basis for Biological Treatment
Design and Operation. J. Sanitary Engr. Div., ASCE. 96:757-778, 1970.
15. Stensel, H.D. and G.L. Shell. Two Methods of Biological Treatment Design.
J. Water Poll. Control. Fed. 46:271-283, 1974.
16. Loehr, R.C. Pollution Control for Agriculture. Academic Press, Inc.
New York. 1977. 383 p.
17. Cullen, E.J. and J.F. Davidson. The Effect of Surface Active Agents on
the Rate of Adsorption of Carbon Dioxide by Water. Chemical Engineering
Science. 6:2, 49-50, 1956.
18. Downing, A.L. and A.G. Boon. Oxygen Transfer in the Activated Sludge
Process. Air and Water Pollution. 5:131-148, 1963.
19. O'Connor, D.J. Effects of Surface Active Agents on Reaeration. Air and
Water Pollution. 5:123-130, 1963.
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20. Gaden, E.L. Jr. Aeration and Oxygen Transport in Biological Systems-
Basic Considerations. In: Biological Treatment of Sewage and Industrial
Wastes. Reinhold Publishing Corp., New York. 1956. 172 p.
21. Jones, D.D., D.L. Day, and A.C. Dale. Aerobic Treatment of Livestock
Wastes. Bulletin 737, University of Illinois at Urbana-Champaign. 1970
55 p.
22. Agricultural Engineers Digest. Oxidation Ditch for Treating Hog Wastes.
AED-14, Midwest Plan Service, Iowa State University, Ames, Iowa. 1970.
23. Agriculture Canada. Canada Animal Waste Management Guide. Publication
1534. Ottawa, Ontario. 1974.
24. Hashimoto, A.G. Characterization of White Leghorn Manure. Proc. Agric.
Waste Management Conf., Cornell University, Ithaca, New York. 1974.
p. 141-152.
25. Holmes, B.J. Effect of Drying on the Losses of Nitrogen and Total Solids
from Poultry Manure. Unpublished M.S. Thesis. Cornell University,
Ithaca, New York. 1973. 97 p.
26. Stewart, T.A. and R. Mcllwain. Aerobic Storage of Poultry Manure. In:
Livestock Waste Management and Pollution Abatement. ASAE. St. Joseph,
Michigan. 1971. p. 261-262.
27. Foree, E.G. and P.L. McCarty. The Decomposition of Algae in Anaerobic
Waters. Technical Report No. 95, Department of Civil Engineering,
Stanford University, Stanford, California. 1968.
28. Anthonisen, A. and E.A. Cassell. Kinetic Model for High-Rate Anaerobic
Digestion. Studies on Chicken Manure Disposal: Part I—Laboratory
Studies, Research Report No. 12, New York State Department of Health,
1968.
29. Woods, J.L. and J.R. O'Callaghan. Mathematical Modelling of Animal Waste
Treatment. J. Agric. Engr. Research. 19:245-258, 1974.
30. Morris, G.R. Anaerobic Fermentation of Animal Wastes: A Kinetic and
Empirical Design Evaluation. Unpublished M.S. Thesis. Cornell Univer-
sity, Ithaca, New York. 1976. 193 p.
31. Nieswand, S.P. An Evaluation of a Full-Scale In-House Oxidation Ditch
for Poultry Wastes. Unpublished M.S. Thesis, Cornell University, Ithaca,
New York. 1974. 140 p.
32. Stratton, F.E. and P.L. McCarty. Prediction of Nitrification Effect on
the Dissolved Oxygen Balance of Streams. Environmental Science and
Technology. 1:405-416, 1967.
121
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33. Loehr, R.C., T.B.S. Prakasam, E.G. Srinath, and Y.D. Joo. Development
and Demonstration of Nutrient Removal from Animal Wastes. Environmental
Protection Technology Series Report No. EPA-R2-73-095. U.S. Environ-
mental Protection Agency, Washington, D.C. 1973. 340 p.
34. Terashima, S., K. Koyama, and Y. Mazara. Biological Sewage Treatment in
a Cold Climate Area. In: EPA Report No. 16100 EXH (R.S. Murphy and
D. Nyquist, eds.) University of Alaska, College, Alaska. 1971.
p. 263-385.
35. Baker, D.R., R.C. Loehr, and A.C. Anthonisen. Oxygen Transfer of High
So]ids Concentrations. J. Environ. Engr. Div., ASCE. 101:759-774, 1975.
36. Hashimoto, A.G. and Y.R. Chen. Turbine-Air Aeration System for Poultry
Wastes. In: Managing Livestock Wastes. ASAE. St. Joseph, Michigan.
1975. p. 530-534.
37. Calhoun, G.D. Design Considerations for the Oxidation Ditch as a Dairy
Manure Waste Management Alternative. Unpublished M.Engr. Report. Cornell
University, Ithaca, New York. 1974. 97 p.
38. Water Pollution Control Federation. Aeration in Wastewater Treatment--
Manual of Practice No. 5^. Washington, D.C. 1970. 96 p.
39. Benjes, H.H. Jr. and R.E. McKinney. Specifying and Evaluating Aeration
Equipment. J. Sanitary Engr. Div., ASCE. 93:55-63. 1967.
40. Stukenberg, J.R., V.N. Wahbeh, and R.E. McKinney. Experiences in Evalu-
ating and Specifying Aeration Equipment. J. Water Poll. Control Fed.
49:66-82, 1977.
41. Walker, J.P. and J. Pos. Caged Layer Performance in Pens with Oxidation
Ditches and Liquid Manure Storage Tanks. Proc. Agric. Waste Management
Conf., Cornell University, Ithaca, New York. 1969. p. 249-263.
42. Jones, D.D., D.L. Day, and J.C. Converse. Field Tests of Oxidation Ditches
in Confinement Swine Buildings. Proc. Agric. Waste Management Conf.,
Cornell University, Ithaca, New York. 1969. p. 160-171.
43. Moore, J.A., R.E. Larson, and E.R. Allred. Study of the Use of the Oxida-
tion Ditch to Stabilize Beef Animal Manures in Cold Climate. Proc. Agric.
Waste Management Conf., Cornell University, Ithaca, New York. 1969.
p. 172-177.
44. Chow, V.T. Open-Channel Hydraulics. McGraw-Hill Book Company, New York.
1959. 680 p.
45. King, H.W. and E.F. Brater. Handbook of Hydraulics. McGraw-Hill Book
Company, New York. 1963.
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46. Sobel, A.T. Physical Properties of Animal Manures Associated with
Handling. In: Farm Animal Wastes. ASAE. St. Joseph, Michigan. 1966.
p. 27-32.
47. Metcalf and Eddy, Inc. Wastewater Engineering. McGraw-Hill Book Company.
New York. 1972. 782 p.
48. Wong-Chong, G.M., A.C. Anthonisen, and R.C. Loehr. Comparison of the
Conventional Cage Rotor and Jet-Aero-Mix Systems in Oxidation Ditch
Operations. Water Research. 8:761-768. 1974.
49. Perry, J.H. Chemical Engineering Handbook. 4th edition. McGraw-Hill
Book Company. New York. 1963.
50. Shukry, A. Flow Around Bends in an Open Flume. Transactions, ASCE.
115:751-779. 1950.
51. Martin, J.H. Unpublished Research Results. Agricultural Waste Manage-
ment Program. Cornell University, Ithaca, New York. 1976.
52. Lawrence, A.W. Modeling and Simulation of Slurry Biological Reactors.
In: Mathematical Modeling and Environmental Engineering. Association
of Environmental Engineering Professors, 8th Annual Workshop. Nassau,
Bahamas. 1972. p. 216-255.
53. Dick. R.I. Role of Activated Sludge Final Settling Tanks. J. Sanitary
Engr. Div-, ASCE. 96:423-436, 1970.
54. McKinney, R.E. and R. Bella. Water Quality Changes in Confined Hog Waste
Treatment. Project Report: Kansas Water Resources Research Institute.
University of Kansas, Lawrence, Kansas. 1967. 88 p.
123
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CHAPTER 5
DESIGN APPROACHES
5.1 Introduction
In the two preceding chapters, the development of process design methodologies
for high-rise, undercage drying and aeration systems for poultry wastes has
been presented. Before either of these design procedures can be utilized,
decisions concerning design variables which represent management options are
necessary. In that these systems can be designed and operated over wide
ranges of values for these variables, an understanding of how these variables
affect performance is necessary. It is the objective of this chapter to
discuss the impact of design decision alternatives on the operating charac-
teristics of these systems and to present approaches to simulate system
performance.
Included in this chapter will be descriptions of several computer programs
designed to assist in the evaluation of alternative design decisions for
specific situations. The computer language used for these programs is the
WATFIV version of FORTRAN IV. In writing these programs, a primary objective
was to make them understandable and usable by individuals having only
limited exposure to the use of computers. Efficiency in programming may
have been sacrificed in certain instances in the interest of charity. How-
ever, the impact on computation costs is negligible due to the simplicity
of each program. The use of these programs, while not a prerequisite for
design, provides ease in evaluating the effects of a wide range of values
for process design variables for specific situations. The programs were
employed in this manner to generate the information presented in the following
discussion of design approaches for these systems.
5.2 High-Rise, Undercage Drying
The objective of the process design of a high-rise, undercage drying system
is the determination of the drying air velocity necessary to provide moisture
reduction to a specified value during the start-up phase of operation. This
level of moisture reduction is important for ridge formation and biological
heat production in the drying manure. Biological heat production is the
critical factor in the high-rise drying process.
In a high-rise, undercage drying system, the magnitude of the required drying
air velocity is dependent on the following independent process design variables
124
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A. Bird density, which is a function of the type of cage system
and the number of birds per cage;
B. Feed energy content;
C. The specified manurial surface moisture content during the
start-up phase of system operation.
An understanding of the relationships between these variables and design dry-
ing air velocity is necessary to identify optimum combinations of these vari-
ables for specific situations.
As noted in Chapter 3, it is not possible to design a high-rise, drying system
to provide a specific final system moisture content. This is due to the inabi-
lity to predict changes in vapor pressure differential due to biological heat
production with time. However, it appears possible to simulate changes in
system moisture content over time by describing the four variables that define
manurial surface moisture content; area factor, moisture loading factor, dry-
ing air velocity, and vapor pressure differential; as time dependent variables.
This provides an opportunity to evaluate various design variables such as the
design value for manurial surface moisture content. It also provides a mecha-
nism to analyse the effect of changes of time dependent variables such as
vapor pressure differential. This section describes the nature of the rela-
tionships between the three independent process design variables and design
drying air velocity and includes a discussion of an approach to simulate high-
rise system performance over time.
5.2.1 High-Rise, Undercage Drying System Design
The process design of a high-rise, undercage drying system for poultry wastes
requires specification of design values for bird density, the quantity of mois-
ture excreted per bird-day, and the manurial surface moisture content during
the start-up phase of system operation. Decisions concerning specifying de-
sign values for these variables should be based upon understanding the rela-
tionships between these factors and design drying air capacity.
Due to the possible combinations of cage systems and numbers of birds per cage
(Tables 3.3 and 3.4), there are six possible design values for bird density.
The relationship between bird density and design drying air velocity with all
other variables held constant, is presented in Figure 5.1. Increases in bird
density significantly affect drying air velocity design values. However, the
ratio of bird density and design drying air velocity (Table 5.1) shows that
this relationship is constant. Therefore, the unit drying air requirements
are independent and any reduction in housing costs per bird will not be offset
by increased costs associated with drying air circulation.
As discussed in Chapter 2, the quantity of moisture excreted per bird-day ap-
pears to be a function of feed metabolizable energy (ME) content (Figures 2.1
and 2.3). As feed ME content decreases, the quantity of moisture excreted and
thus the evaporative capacity requirements of a high-rise drying system will
increase. This translates into increased drying air velocity design values.
125
-------
ro
u
cc
<
o
o:
Q
o
in
LJ
Q
1.0
0.9
0.8
0.7
0.6
AREA FACTOR =1.0
VAPOR PRESSURE DIFFERENTIAL = 325 pascals
MOISTURE PRODUCTION = 90.6gms H20/bird-day
MANURIAL SURFACE MOISTURE CONTENT =235% d.b.
NOTE: I. m/sec x 196.8 = ft./min.
2. birds/m2 ^ 10.76 = birds /ft2
FLAT DECK AND STAIR
STEP CAGE SYSTEMS
25.8 29.1 32.3
TRIPLE DECK CAGE
SYSTEM
31.8 35.8 39.8
Figure 5.1.
BIRD DENSITY, birds/m*
Effect of type of cage system and management practices
(no. of birds/cage) on drying air velocity design requirements.
-------
TABLE 5.1. RATIOS OF BIRD DENSITY TO DESIGN
DRYING AIR VELOCITY
Bird Density, Design Drying Bird Density/Design
birds/m Air Velocity, m/sec Drying Air Velocity
Ratio
25.8
29.1
32.3
31.8
35.8
39.8
0.71
0.80
0.89
0.87
0.98
1.09
36.3
36.4
36.3
36.6
36.5
36.5
The relationship between design drying air velocity and the quantity of moisture
excreted per bird-day is presented in Figure 5.2. Small changes in the quan-
tity of moisture excreted per bird-day do not drastically change design drying
air velocities. However, the desirability of minimizing the quantity of mois-
ture excreted by utilizing feeds with a high ME content is illustrated by
Figure 5.2.
The practice of utilizing feeds with high ME contents will serve to reduce costs
associated with drying air circulation. The quantity of total solids produced
will also be reduced (Figure 2.1). However, it should be recognized that the
management decision to use a high ME feed can not be based solely on waste manage-
ment factors. Nutritional aspects must be considered as well as possible eco-
nomic trade-offs. It is possible that increased feed costs due to the use of a
high ME feed could be equal to or greater than any waste management cost
reductions.
The selection of a design value for manurial surface moisture content is per-
haps the most ill-defined aspect of high-rise, undercage drying process design.
The value selected must be conservative enough to insure successful system
performance but not require an unreasonable design drying air velocity. The
relationship between the design values for manurial surface moisture content
and design drying air velocity is illustrated in Figure 5.3. As shown, the
rate of change of design drying air velocity increases as the specified manu-
rial surface moisture content decreases with 235 percent appearing to be a
reasonable value in terms of design drying air velocity.
The largest propeller type fan available for agricultural application has a
capacity of 9.44 nT/sec (20,000 ftVmin). A fan of this capacity will provide
an average drying air velocity of 0.72 m/sec (143 ft/min) in a cross-section
area of 13 nr (140 ft2). This is one-half of the total manure storage cross-
sectional area in a typical 2.2 m (40 ft) wide high-rise poultry house. Thus,
127
-------
ro
CO
u
0)
V
K
O
3
UJ
UJ
o
1.30
1.20
1.10
a: l.OO
0.90
0.70
AREA FACTOR = 1.0
VAPOR PRESSURE DIFFERENTIAL = 325 pascals
BIRD DENSITY = 29.1 birds/m2
INITIAL MANORIAL SURFACE
MOISTURE CONTENT = 235% d. b.
U NOTE: m/sec x 196.8 = ft/min
70
80
90
100
110
120
130
140
150
MOISTURE EXCRETED, gms H20/ bird-day
Figure 5.2. Relationship between quantity of moisture excreted and design
drying air velocity.
-------
ro
0)
at
O
3
LJ
O
oc.
o
AREA FACTOR = 1.0
VAPOR PRESSURE DIFFERENTIAL = 325 pascals
MOISTURE PRODUCTION = 90.6 gms HO/ bird-day
BIRD DENSITY = 29.1 birds / m2
NOTE'- m/sec x 196.8 = ft/min
0.2
120
160
200
240
280
320
360
400
INITIAL MANURIAL SURFACE MOISTURE CONTENT,
% dry basis
Figure 5.3. Relationship between initial manurial moisture content and
design drying air velocity.
-------
the design value of 235 percent, dry basis, (Table 3.5) appears reasonable
in terms of both available equipment and past experience (Table 3.1).
The results of the preceding analyses show that both feed energy content and
the specified manurial surface moisture content design decisions can signi-
ficantly affect design drying air velocity and increase requirements per bird.
However, increases in bird density do not increase drying air velocity
requirements per bird. Thus, maximizing bird density to minimize housing
costs will not be offset by increased waste management costs.
5.2.2 Simulation of System Performance
Although it is not possible to design a high-rise, undercage drying system
to provide a specific fir.al system moisture content, it does appear possible
to simulate system performance over time and to predict a final system
moisture content for specific patterns of change in vapor pressure differential
with time that may be anticipated. This approach provides aimethod of
evaluating the effect of design decisions such as decreasing design drying
air velocity on system performance. It also provides a mechanism for evaluating
different patterns of change in vapor pressure differential with time for a
specific design.
A mathematical model was developed to predict changes in system moisture con-
tent with cumulative time of operation based on the hypothesis that system
moisture content is simply the reflection of past surface moisture contents.
This model considers area factor, bird density and thus the moisture loading
factor, vapor pressure differential, and drying air velocity as time dependent
variables. At specified increments in time of operation, values for manurial
surface moisture content are computed. System moisture content is then
calculated by averaging previously computed values for manurial surface
moisture content.
In order to test the validity of this simulation approach, the performance of
a full scale system was simulated and then compared with observed results (1).
Area factor, bird density, vapor pressure differential, and drying air velocity
were described as time dependent variables using available data from the
full scale study. Using linear regression analysis of the observed change
in the area factor with cumulative time of operation (Figure 3.8), the following
relationship expressing the area factor at any time, T, in days (AFT) was
mathematically defined.
AFT = 0.0016(T) + 1.0 (5.1)
During the year of system operation which was simulated, mortality which
results in decreased bird density followed a normal linear pattern. Losses
averaged one percent of the number of hens housed per month. This translates
mathematically as follows:
130
-------
BDT = -0.01(T)(BDI) (5.2)
9
where: BDI = initial bird density, birds/m
T - cumulative time of operation, days
p
BDT = bird density at any time, birds/m
Substituting BDT for BD in Equation 3.9, the moisture loading factor at any
time (MLFT) can be estimated.
The change in vapor pressure differential with time was defined mathematically
using both 1970-71 and 1971-72 data (Table 3.1 and Figure 3.13). Using regres-
sion analysis, these data were best described by two separate linear relation-
ships. For values of T between 0 and 200 days:
VPDT = 2.3(T) + 238 (5.3)
and for T between 200 and 360 days :
VPDT = H.2(T) - 2148 (5.4)
Based upon the design approach for determination of drying air fan velocity
(Chapter 3), average drying air velocity at the beginning of system operation
for 1971-72 was estimated to be 0.40 m/sec (1). Due to a decrease in manure
storage cross-sectional area resulting from the accumulated manure, it was
further estimated that average drying air velocity increased to 0.59 m/sec at
the end of the 1971-72 cycle. Assuming that the velocity increase was linear
over time, the average drying air velocity at any time in days (AVT) over the
1971-72 manure accumulation cycle was defined as:
AVT = 0.00045(T) + 0.40 (5.5)
For this simulation, the reported values^for this system of 99 gm H^O/bird-day
for moisture production and 29.1 birds/m for initial bird density were used.
The reader should understand that Equations 5.1 through 5.5 are specific for
the system studied by Sobel and do not necessarily represent general relation-
ships.
The results simulated by the model for manurial surface moisture content and
average system moisture content are presented in Figure 5.4. These results
indicate that surface moisture content decreases more rapidly than average
system moisture content. This is due to the lack of additional drying once a
manure surface ceases to be exposed due to subsequent manure depositions.
131
-------
90
.Ł 80
o
-O
0>
70
eo
o
o
UJ
cr
ID
h-
C/)
O
40
30
SIMULATED AVERAGE
SYSTEM MOISTURE CONTENT
SIMULATED MANURIAL
SURFACE MOISTURE
CONTENT
OBSERVED-M3
FINAL SYSTEM
MOISTURE CONTENT
ESTIMATED FINAL'
MANURIAL SURFACE
MOISTURE CONTENT
I
I
0
60 120 180 240 300 360
CUMULATIVE TIME OF OPERATION, days
420
Figure 5.4. Simulated results from a high-rise, undercage drying system
performance predictive model.
132
-------
There is good agreement between the simulated final system moisture content on
day 360 of 66 percent, wet basis (WB),and the observed value of 63 percent,
WB(1). Average final manurial surface moisture content was not measured but
was estimated to be 50 percent, WB. The simulated value was 48 percent, WB.
Unfortunately, additional observed data concerning average surface and system
moisture contents at intermediate points in time of system operation are
lacking. This information would serve to confirm the accuracy or identify th.
limits of this simulation approach.
This model was used to evaluate the effects of variation in moisture produc-
tion, initial drying air velocity, and initial bird density on final manurial
surface and average system moisture contents at day 360 of system operation.
Simulations were performed for the pattern of change in vapor pressure differ-
ential with cumulative time of operation expressed in Equations 5.3 and 5.4
(Table 3.1 and Figure 3.13). In addition, simulations utilizing only Equation
5.3 were carried out to assess the importance of the rapid increase in vapor
pressure differential following 200 days of cumulative operation observed in
full scale system evaluations (Figure 3.13). These results are presented in
Table 5.2. Values in parentheses resulted from the lower rate of increase in
vapor pressure differential expressed solely by Equation 5.3.
These results show that higher values for moisture production and/or bird den-
sity must be compensated for with higher design drying air velocity to provide
satisfactory system performance. Based on experience, an average system mois-
ture content at day 360 of system operation of 66 percent, WB, or less appears
desirable.
Comparison of average system moisture contents for the two patterns of change
in vapor pressure with time of operation serves to reinforce the importance of
biological heat production and the resultant effect on vapor pressure differen-
tial in the high-rise drying process. While it appears that a drying air
velocity of 0.4 m/sec will provide satisfactory system performance for 100 gm
H,0/bird-day and 29.1 birds/m2 with significant biological heat production, a
higher drying air velocity will be required if biological heat production is
minimal. This can be translated into higher costs for equipment and operation.
This mathematical model provides a method to examine the effects of design
variables and other factors on system performance. In the design of these sys-
tems, minimizing moisture production within the limits of practicality and
providing conditions during the start-up phase of system operation conducive
to biological heat production appear to be the most important factors.
5.2.3 Computer Design Programs
Two computer programs have been developed to assist in the process design of
high-rise, undercage drying systems. The first program-, high-rise, undercage
drying design analysis; was designed to analyze the effects of variation in
moisture production per bird-day, bird density, and the design value for manu-
rial surface moisture content on design drying air velocity. This program is
based on the process design equations, Equations 3.9 and 3.13. The second
program, high-rise, undercage drying - simulation of system performance, was
developed to predict system performance over time for various combinations of
133
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TABLE 5.2. EFFECTS OF PROCESS DESIGN VARIABLES ON FINAL
MANORIAL SURFACE AND SYSTEM MOISTURE CONTENTS
IN A HIGH-RISE, UNDERCAGE DRYING SYSTEM
Day 360
Manurlal Surface Moisture
Content, % WB
Average System Moisture
Content, % WB
to
Initial drying air velocity
Initial bird density
Moisture production
Moisture production
Initial bird density
Initial drying air vel
Moisture production
Initial drying air velocity
Initial bird density
= 0.4 m/sec ?
= 29.1 birds/m
- 80 gm/bird-day
= 100 gm/bird-day
= 120 gm/bird-day
= 100 gm/bird-day
= 29.1 birds/mz
= 0.4 m/sec
= 0.8 m/sec
=1.0 m/sec
= 100 gm/bird-day
=0.4 m/sec
- 29.1 birds/flu
= 32.3 birds/rru
=39.8 birds/nT
45.4* (58.0)**
48.2 (60.7)
50.4 (62.8)
48.2 (60.7)
39.7 (52.3)
37.1 (49.5)
48.2 (60.7)
49.4 (61.9)
52.0 (64.5)
63.4 (67.1)
65.8 (69.4)
67.7 (71.3)
65.8 (69.4)
58.2 (61.9)
55.6 (59.3)
65.8 (69.4)
66.9 (70.5)
68.9 (72.5)
* For T = 0 through 200, VPDT = 2.3T + 238, and for T = 200 through 360, VPDT = 14.27 - 2148
** For T = 0 through 360, VPDT = 2.3T + 238
-------
design values for moisture production per bird-day, bird density, and design
drying air velocity. The mathematical model discussed in the previous section
is the basis for this program. Flow diagrams and source listings for both pro-
grams are presented in the Appendix, Figures A-2 through A-5. The following
is a brief description of user input and computed output for both programs.
The high-rise, undercage drying design analysis program is a combination of
three subprograms for the sequential examination of moisture production, bird
density, and the design manurial surface moisture content as variables. For
this program, the user must specify the following:
A. Values for area factor and vapor pressure differential repre-
sentative of start-up conditions ;
B. Values for manurial surface moisture content, dry basis (DB)
and bird density and a range of values for moisture production;
C. Values for manurial surface moisture content, DB and moisture
production, and a range of values for bird density;
D. Values for moisture production and bird density, and a range
of values for manurial surface moisture content, DB.
For each combination of values; moisture production, bird density, and manurial
surface moisture content, DB; this program will compute design drying air velo-
cities for each value of the variable parameter in each combination.
For the second program; high-rise, undercage drying - simulation of system per-
formance; the user must specify a set of design values for moisture production,
initial drying air velocity, and initial bird density. For each set of design
values, this program will compute manurial surface and average system moisture
contents at specified time intervals over a one-year operating cycle.
5.3 Aerobic Biological Stabilization
Aeration systems for poultry wastes can be designed and operated as either
batch or continuous flow reactors. The batch mode of operation combines stor-
age with odor control and waste stabilization, whereas separate storage faci-
lities are required with a continuous flow system. Both modes of operation
are similar in that aeration requirements and volumetric ultimate disposal re-
quirements are inversely related. Thus, trade-offs between aeration and ulti-
mate disposal costs exist for both batch and continuous flow modes of operation.
While the process designs of these alternatives are based on the same funda-
mental concepts, the independent process design variables differ. In order
to evaluate the trade-offs for each operational mode, an understanding of
the relationships between the respective process design variables and aeration
and ultimate disposal requirements is necessary. It is the objective of this
section to describe the relationships between design variables and operating
characteristics for each method of operation and to discuss the trade-offs
created by various decisions concerning design variables.
135
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The relationships presented in the following discussions are based on the raw
waste characteristics for poultry manure presented in Table 4.5. It should be
understood that while the general nature of the following relationships will
not change, specific values will vary with changes in raw waste characteristics.
Thus, in the design of specific systems, anticipated raw waste characteristics
should be delineated for process design calculations.
5.3.1 Continuously Loaded, Batch Aeration System Design
A continuously loaded, batch aeration system has two independent process design
variables. They are system volume per bird and the operating period for the
batch cycle. Both aeration capacity and ultimate disposal requirements are
dependent on these variables.
In a batch system, the solids retention time (SRT) is a dependent variable
which continually increases with time of operation (Equation 4.34). Thus,
removal efficiencies (Equations 4.20 through 4.23) and total carbonaceous and
nitrogenous oxygen demands (Equations 4.27 and 4.28) will increase with time
changes in both carbonaceous and nitrogenous oxygen demands as a function of
cumulative batch system operation time are presented in Figure 5.5. In a
batch system, nitrogenous oxygen demand increases until about day 80, at which
point it becomes constant since the biodegradable limit of organic nitrogen
in poultry manure is reached. The same patter occurs for carbonaceous oxygen
demand which becomes constant at about day 110 of the batch operation. Thus,
maximum removal of organic nitrogen and carbonaceous oxygen demand will occur
within 80 and 100 days, respectively.
A characteristic of a continuously loaded, batch aeration system is he continual
increase in the mixed liquor total solids (MLTS) concentration as the time of
operation increases. This is due to the accumulation of unstabilized biode-
gradable and refractory fractions of total solids. The rate of change of MLTS
concentration in a batch system is a function of both system volume per bird
and cumulative time of operation. A comparison of the rates of increase of
MLTS concentrations for system volumes of 20 Ł/bird and 40 Ji/bird is presented
in Figure 5.6.
The rate of increase in MLTS concentration is non-linear and decreases with
time of operation. This is due to the increase in SRT and hence increased
biodegradable solids destruction. As system volume per bird increases, the
operating period for a batch cycle to reach a maximum or desired MLTS concen-
tration also increases. However, the increase in time is greater than that
which would be provided solely by dilution. The difference is due to increased
biodegradable solids destruction.
A comparison of calculated time periods to reach a MLTS concentration of 60 gm/Ł
for system volumes of 10 Ł/bird through 40 2,/bird is presented in Figure 5.7.
A 100 percent increase in system volume per bird, 20 Ł/bird to 40 Ł,/bird,
increases the time period to reach 60 gm MLTS/Ł by 125 percent. The use of 60
gm as a maximum value for MLTS concentration in a batch aeration system should
not be interpreted as the identification of an absolute upper limit for this
136
-------
500
5? 300
ijo
° 200
E 100
-CARBONACEOUS OXYGEN DEMAND
NITROGENOUS OXYGEN DEMAND
I
I
20 30 40 50 60 70 80
CUMULATIVE TIME OF OPERATION, days
90
Figure 5.5. Changes in carbonaceous and nitrogenous oxygen demands in a
batch aeration system for poultry wastes.
100
-------
CO
oo
10
20
30 40 50 60 70 80
CUMULATIVE TIME OF OPERATION, days
90
100
Figure 5.6. Comparison of rate of increase in MLTS concentration with
time as a function of system volume per bird.
-------
in
>»
o
140 —
120
100
tr
LJ
S 80
u.
o
I-
LJ
60
40
20
10 20 30 40
SYSTEM VOLUME, //bird
Figure 5.7. Cumulative time of batch system operation to reach
a mixed liquor total solids concentration of 60 gm/Ł.
139
-------
parameter. However, when aeration capacity and mixing requirements are consi-
dered, an upper limit for MLTS concentrations of about 60 gm/Ł appears prac-
tical.
The effect of increasing system volume per bird on ultimate disposal require-
ments is presented in Table 5.3. Increasing system volume up to 30 Ł/bird
will decrease yearly ultimate disposal requirements. Beyond 30 Ł/bird, these
requirements become essentially constant.
TABLE 5.3. ULTIMATE DISPOSAL REQUIREMENTS FOR
A BATCH AERATION SYSTEM AS RELATED TO
SYSTEM VOLUME PER BIRD
System Volume per Bird, Ultimate Disposal Requirements,
Ł/bird &/bird/year*
10 135
20 122
30 110
40 108
* Based upon a mixed liquor total solids concentration of 60 gm/Ł.
The increase in MLTS concentration in a batch system is the mechanism by which
storage of residual solids is provided. However, this phenomenon has an ad-
verse effect on the efficiency of oxygen transfer. This results from the de-
crease in a, the ratio of the overall oxygen transfer coefficient, K,a, in
the aerated manure to K. a in tapwater as MLTS concentration increases. The
relationships between a and MLTS concentration for aerated poultry manure
slurries have been presented in Equations 4.30 through 4.32. As a decreases,
the aeration capacity necessary to meet a given microbial oxygen demand in-
creases (Equation 4.33).
A comparison of carbonaceous oxygen demand and aeration capacity requirements
with time of operation for a system volume of 30 Ł/bird is presented in Figure
5.8. From day 20 through day 100, carbonaceous oxygen demand increases 40
percent, while required aeration capacity increases 254 percent. Reducing the
time period of the batch cycle and therefore the maximum MLTS concentration
will reduce aeration capacity requirements but will increase the volume of
stabilized waste requiring ultimate disposal. A comparison of aeration and
ultimate disposal requirements as a function of cumulative operation time for
a system volume of 30 a/bird is presented in Table 5.4. A plot of ultimate
disposal versus aeration capacity requirements for system volumes of 20 Ł/bird,
30 Ł/bird, and 40 Ł/bird (Figure 5.9) shows that this relationship is indepen-
dent of system volume per bird. It also illustrates that beyond a required
aeration capacity of about 500 gm 0^/1000 bird-hours, only minor decreases in
140
-------
1200
1000
O
.c
I
800
O
O
O 600
o>
z- 400
UJ
O
X
° 200
0
SYSTEM VOLUME = 30 J2/BIRD
REQUIRED AERATION
CAPACITY
CARBONACEOUS
OXYGEN DEMAND
I
20 30 40 50 60 70 80
CUMULATIVE TIME OF OPERATION, days
90
100
Figure 5.8. Comparison of carbonaceous oxygen demand and required aeration
capacity over the operating period for a batch cycle.
-------
TABLE 5.4. MAXIMUM AERATION CAPACITY AND ULTIMATE DISPOSAL REQUIREMENTS
FOR A BATCH SYSTEM WITH VOLUME OF 30 &/BIRD AS RELATED TO
CUMULATIVE TIME OF OPERATION
ro
Cumulative Time
of Operation,
days
20
30
40
50
60
70
80
90
100
Mixed Liquor
Total Solids
Concentration, gm/n
15.0
21.8
28.3
34.3
40.0
45.2
50.0
54.4
59.8
Required Aeration
Capacity, gm OJ
1000 bird-hours
329
350
413
490
584
700
846
1031
1165
Ultimate Disposal
Requirements,
Ł/bird/year
548
365
274
219
182
156
137
122
no
-------
CM
CO"
f-
2
LL)
2
LJ
CE
ID
O ,_
LJ O
tr o>
CO
Q
LJ
800
600
< -D 400
O !5
200
0
20 J?/BIRD
30Jl/BIRD
40J?/ BIRD
1
0
300
400
500
600
700
800
900
IOQO
1100
1200
REQUIRED AERATION CAPACITY,
gmsCL/IOOO bird-hours
Figure 5.9. The relationships between ultimate disposal and aeration
requirements in a continuously loaded, batch aeration
system for poultry wastes.
-------
ultimate disposal volume occurs. Since both fixed and operating costs increase
as aeration capacity requirements increase, there is little apparent value in
achieving a very low ultimate disposal volume.
In the design of a batch aeration system, factors such as storage and/or ulti-
mate disposal requirements can not be considered independently. For effective
system design, both factors must be considered in conjunction with aeration
requirements. Although increasing system volume and the length of the batch
cycle operating period increases storage capability and reduces ultimate dis-
posal requirements, this may not provide an optimum design solution. Depending
on the relative costs of aeration and ultimate disposal, it may be more desir-
able to select a batch cycle operating period which reduces aeration require-
ments and increases the stabilized waste volume. Where weather and/or other
constraints limit ultimate disposal opportunities, additional non-aerated sto-
rage may provide the least cost system.
5.3.2 Continuous Flow Aeration System Design
The process design of a continuous flow aeration system for poultry wastes re-
quires the identification of values for SRT and MLTS concentration compatible
with waste management objectives. For the continuous flow mode of operation,
SRT and MLTS concentration are independent process design variables. Both
aeration and ultimate disposal requirements are dependent on these variables.
An advantage of the continuous flow as compared to the batch mode of aeration
system operation is that SRT is an independent process design variable. There-
fore, a desired level of waste stabilizaton consistent with overall waste man-
agement objectives can be achieved by selecting the appropriate SRT value.
Relationships between SRT and removal efficiencies for the four major waste
characterization parameters associated with poultry manure are presented in
Figures 5.10 and 5.11. These relationships were derived from the process de-
sign equations, Equations 4.20 through 4.23. As SRT and therefore the degree
of waste stabilization increases, carbonaceous and nitrogenous oxygen demands
also increase (Figure 5.12).
With the exception of situations where a high degree of nitrogen removal is
required due to limitations of available land for ultimate disposal, it appears
that odor control will be the principal waste management objective for these
systems. In these situations, a high degree of waste stabilization and thus a
long SRT does not appear warranted. Decreasing SRT from 40 days to 10 days will
reduce both carbonaceous and nitrogenous oxygen demands by 24 percent (Figure
5.12). These decreases can be translated into reduced fixed and operating costs
for aeration.
A second advantage of the continuous flow versus batch mode of aeration system
operation is the ability to maximize oxygen transfer efficiency by maintaining
low MLTS concentrations. However, the absence of practical liquid-solid sepa-
ration and solids thickening approaches for these wastes results in an increased
volume of effluent requiring ultimate disposal as oxygen transfer efficiency
is maximized. Thus, a trade-off also exists with a continuous flow system
between aeration and ultimate disposal requirements.
144
-------
o
z
UJ
o
U_
U.
UJ
LJ
CC
60
50
40
30
20
0
Figure 5.10.
VOLATILE SOLIDS
TOTAL SOLIDS
10 20 30 40
SOLIDS RETENTION TIME, days
Design relationships between SRT and removal of
total and volatile solids.
O
UJ
o
UJ
o:
70
60
r: 50
UJ 40
2 30
20
Figure 5.11
ORGANIC NITROGEN
CHEMICAL OXYGEN DEMAND
10 20 30 40
SOLIDS RETENTION TIME, days
Design relationships between SRT and removal of organic
nitrogen and COD.
145
-------
ZJ
o
O
O
O
to
Ł
UJ
X
o
800
700
600
500
400
300
200
100
TOTAL OXYGEN
DEMAND
CARBONACEOUS OXYGEN
DEMAND,
NITROGENOUS OXYGEN
DEMAND
10 20 30 40
SOLIDS RETENTION TIME, days
Figure 5.12. Design relationships between SRT and carbonaceous
nitrogenous and total oxygen demands.
146
-------
Representative changes in aeration requirements as a function of MLTS concen-
tration for systems operated at 10 and 30 day SRTs are presented in Figure 5.13.
Increasing design MLTS concentration up to 20 gm/Ł does not increase aeration
requirements which are necessary to meet the microbial oxygen demand. However,
an increase from 20 gm/Ł to 60 gm/Ł produces an increase in aeration require-
ments of 151 percent.
In a continuous flow system, the volume of stabilized waste requiring ultimate
disposal decreases as the equilibrium MLTS concentration increases. This
relationship is illustrated in Figure 5.14. In order to identify an optimum
design value for MLTS concentration in a continuous flow aeration system, it
is necessary to analyse the trade-offs between aeration and ultimate disposal
requirements. A plot of ultimate disposal versus aeration requirements for
SRTs of 10 and 30 days (Figure 5.15) shows these relationships. A dependence
on SRT exists at low MLTS concentrations but does not occur at higher MLTS con-
centrations. Figure 5.15 also illustrates that design below an ultimate dis-
posal requirement of 200 Ł/bird-year provides only moderate reductions in ulti-
mate disposal volumes. However, aeration capacity requirements increase rapidly
as will fixed and operating costs. Thus there is little apparent value in re-
ducing ultimate disposal requirements to extremely low levels.
In a continuous flow system, system volume is a function of both SRT and MLTS
concentration. The relationship between SRT and system volume per bird for
MLTS concentrations of 20 gm/a and 40 gm/Ł are shown in Figure 5.16. The mag-
nitude of increase of system volume with SRT is significantly greater at lower
MLTS concentrations. Relationships between system volume per bird and MLTS
concentration for SRT's of 10 and 30 days are presented in Figure 5.17.
In designing a continuous flow aeration system, decreasing SRT and/or increas-
ing MLTS concentration will decrease system volume and associated capital
costs. This will reduce mixing requirements and possibly alleviate problems
due to sediment accumulations. In that increasing MLTS concentration beyond
20 gm/Ł will increase aeration requirements (Figure 5.13), minimizing SRT,
while still achieving odor control and stabilization, appears to have merit
for reducing both system volume and aeration requirements (Figure 5.12).
In summary, the effective process design of a continuous flow aeration system
for poultry wastes requires analysis of the relationships involving SRT and
MLTS concentration with resect to aeration capacity, ultimate disposal re-
quirements, and system volume. The relative costs of these factors should
determine an optimum design, a least cost system.
5.3.3 Comparison of Batch versus Continuous Flow Modes of Operation
Comparison of the trade-offs between ultimate disposal and aeration capacity
requirements for the batch and continuous flow modes of aeration system opera-
tion (Figures 5.9 and 5.15) indicates little difference in the characteristics
of the two operational modes. Since it also appears that the storage aspect
of a batch system is offset by increased aeration capacity requirements, dif-
ferences in system volume per bird and additional storage facility requirements
are also minimal. The continuous flow operational mode has the potential of
minimizing aeration and ultimate disposal requirements . However,
147
-------
o
-o
^
lo
O
O
O
"
to
E
UJ
2
UJ
ID
o
UJ
cr
o
UJ
1000
900
800
700
600
500
400
300 —
200
SRT = 30 DAYS
SRT= 10 DAYS
1
I
I
Figure 5.13.
10 20 30 40 50 60
MIXED LIQUOR TOTAL SOLIDS,
CONCENTRATION, gms/J?
Aeration requirements as a function of MLTS concentration
in continuous flow aeration systems.
148
-------
CO
h-
z
LJ
2
LJ
01
= fc
O •
cr i
TJ
1200
1000 h
800i-
6001-
CO
Q
LJ
400h-
200 U
0
MIXED LIQUOR TOTAL SOLIDS
CONCENTRATION, gms/*
Figure 5.14. Ultimate disposal requirements as related to MLTS
concentration in a continuous flow system.
149
-------
1200
en
o
LJ
^
LJ
o
LJ
o:
1000
800
600
LJ
<
<=; 400
10 DAY SRT
30 DAY SRT
200
1
I
I
I
400
600
800
1000
REQUIRED AERATION CAPACITY,
gms 02/IOOO bird-hours
Figure 5.15.
The relationship between ultimate disposal
aeration requirements in a continuous flow
aeration system for poultry wastes.
and
-------
10 20 30
SOLIDS RETENTION TIME, days
Figure 5.16. Design relationships between SRT and system volume
for MLTS concentrations of 20 gm/Ł and 40 gm/&.
151
-------
S 40 -
o
O
>
u
CO
"0 10 20 30 40 50 60
MIXED LIQUOR TOTAL SOLIDS CONCENTRATION
Figure 5.17 Design relationships between MLTS concentration and
system volume for 10 day and 30 day SRT's.
152
-------
this potential can only be realized when effective liquid-solids separation
and solids thickening techniques are developed.
5.3.4 Computer Design Programs
The process design methodologies for both batch and continuous flow aeration
systems (Chapter 4) have been incorporated into computer programs to assist
design computations for specific situations. Flow diagrams and source listings
for both programs are presented in the Appendix, Figures A-6 through A-9.
The following is a brief discussion of user input and computed output for both
programs.
For the batch system design program, the user must specify the following:
A. Fixed constant values for substrate removal relationships for
poultry wastes (Table 4.4);
B. Raw waste characteristics expressing each parameter as gm/bird-
day;
C. The number of birds for the system under consideration;
D. A selected value or range of values for system volume per bird,
i/bird; .
E. A selected value or range of values for day of operation in a
batch cycle, days.
For each specified value of system volume per bird, this program will compute
the following design information for each day of operation:
A. The residual quantity, gm/bird-day, and the percent removal for
each waste characterization parameter;
B. The mixed liquor total solids concentration, gm/Ł;
C. Carbonaceous, nitrogenous, and total oxygen demands, gm 02/hour;
D. Alpha;
E. Required aeration capacity to meet the carbonaceous, nitrogenous,
and total oxygen demands, gm CL/hour.
In order to utilize the continuous flow system design program, the user must
specify the following:
A. Fixed constant values for substrate removal relationships for
poultry wastes (Table 4.4);
B. Raw waste characteristics expressing each parameter as gm/bird-
day;
153
-------
C. The number of birds for the system under consideration;
D. A selected value or range of values for SRT;
E. A selected value or range of values for MLTS concentration.
For each specified value of SRT, this program will compute the following de-
sign information for each MLTS concentration:
A. The residual quantity, gm/bird-day, and the percent removal
for each waste characterization parameter;
B. Carbonaceous, nitrogenous, and total oxygen demands, gm Cu/hour;
C. Alpha;
D. Required aeration capacity to meet the carbonaceous, nitrogenous,
and total oxygen demands, gm CL/hour;
E. System volume, Ł;
F. Flowrate to maintain an equilibrium MLTS concentration, Ł/day.
The computed flow rate value also represents ultimate disposal requirements
in the absence of a liquid-solid separation process.
5.4 Referencs
1. Sobel, A.T. The High-Rise System of Manure Management. AWM 76-01. Dept.
of Agricultural Engineering, Cornell University, Ithaca, New York. 1976.
45 p.
154
-------
CHAPTER 6
SYSTEM COMPARISONS
6.1 Introduction
In terms of odor control and the reduction of water pollution potential, both
high-rise, undercage drying and aeration systems represent feasible poultry
waste management alternatives. However, due to differences such as location,
specific waste management objectives, and overall management practices, neither
system will be ideal for all situations. The objective of this chapter is to
discuss the relative merits of each system and to provide economic projections
which can serve as a basis for system selection for specific situations.
Included will be odor control capability, plant nutrient value, and refeeding
potential of the stabilized wastes for both systems.
6.2 Odor Control
With proper design and operation, both high-rise, undercage drying and aerobic
biological stabilization systems are effective odor control techniques for
poultry wastes. In addition, these waste management approaches have the
capability of reducing gaseous ammonia concentrations within poultry houses.
However, differences in both odor and gaseous ammonia control capabilities
exist between these approaches.
Results of a pilot plant scale comparison of odor levels and poultry house
atmospheric ammonia concentrations (Table 6.1) have shown that aeration can be
a more effective odor and ammonia control technique.
TABLE 6.1. COMPARISON OF ODOR LEVELS AND POULTRY HOUSE
ATMOSPHERIC AMMONIA CONCENTRATIONS FOR AERATION
AND DRYING SYSTEMS (1)
Gaseous Ammonia
System Odor Level* Concentration, mg/m
Oxidation Ditch 1,1 < 1
Forced Air, Undercage
Drying 3.7 1-2
*Ranked on a scale of 0 to 10 with 10 equal to a very offensive odor.
155
-------
A human panel was used in this study to evaluate the odor level generated by
each system (2). Poultry manure collected and stored under uncontrolled
anaerobic conditions was ranked near 8. Gaseous ammonia concentrations for
each system were determined by scrubbing the ventilation air at the exhaust
fans (3).
The aeration capacity of the oxidation ditch compared in Table 6.1 was
adequate to meet both the carbonaceous and nitrogenous oxygen demands. Higher
gaseous ammonia concentrations will occur when aeration capacity is sufficient
to satisfy only the carbonaceous oxygen demand. However, a comparable level
of odor control has been demonstrated at this level of oxygen transfer (4).
The drying system compared in Table 6.1 differed from the "typical" high-rise
system in that long term storage was not provided. In addition, the average
moisture content of the manure removed from this system; 45 percent, wet basis
(WB); is below the reported average system moisture content of 63 percent,
WB for a high-rise, undercage drying system (5). Thus, odor levels and atmos-
pheric ammonia concentrations for high-rise, undercage drying systems may
be slightly greater than those values reported in Table 6.1.
These results, along with other observations, suggest that an aeration system
may be the preferable waste management alternative in situations where a high
degree of odor control is necessary. If requirements are less stringent, the
degree of odor control provided by high-rise, undercage drying may be
sufficient.
6.3 Economic Comparison
A major factor in the decision to employ a particular waste management system
will be the relative cost of each alternative. While cost information relative
to the oxidation ditch and high-rise, undercage drying has not been totally
lacking, available information has focused on operating costs. Moreover,
differences in factors such as size of operation and level of technology
development have made comparisons on an equal basis impossible. The objective
of this section to present an analysis of the costs associated with comparable
oxidation ditch and high-rise, undercage drying systems as well as labor
requirements for ultimate disposal.
To provide an equal basis for an economic comparison, system designs based on
respective design methodologies (Chapters 3 and 4) and the discussion of
design approaches (Chapter 5) were developed. The rationale for this approach
instead of basing cost analyses on existing systems was to eliminate differences
such as number of birds, waste characteristics, and bird density which varies
with type of cage system and number of birds per cage. Differences in these
factors can indirectly effect waste management costs. Common criteria used in
the design of both waste management systems for this comparison are summarized
in Table 6.2. It was assumed that costs for cages, feeding equipment, ventila-
tion fans, etc., would be equal for both waste management systems. Thus, these
items were excluded from consideration since the costs of interest are those
due to the different waste management systems.
156
-------
TABLE 6.2. COMMON CRITERIA FOR OXIDATION DITCH AND
HIGH-RISE DRYING SYSTEMS DESIGN
No. of Birds
Type of Cage System
Management Practices
Building
Building Structural Design
30,000
Full Stairstep, 4 Rows
4 Birds per 31 cm x 46 cm
(12 in. x 18 in.) cage
12.8 m x 152.4 m (42 ft x 500 ft)
Timber Column
6.3.1 Waste Management Systems Design
The primary design objective for each system was odor control with the degree
of waste stabilization dependent on that factor. The following is a brief
discussion of each waste management design.
6.3.1.1 High-Rise, Undercage Drying
Using suggested design values (Table 3.5), the average drying air velocity to
provide odor control and permit handling of manure as a solid for the criteria
presented in Table 6.2 was determined to be 0.78 m/sec (154 ft/min). Moisture
production was assumed to be 100 gm H20/bird-day. A velocity of 0 78 m/sec
requires drying air circulating fans with capacities of 9.4 m3/sec (20,000
ft3/min) spaced at 30 m (100 ft) intervals. A 1.2 m, 0.746 kw (48 in., 1.0
h.p.) fan will provide an airflow of 9.4 m3/sec. For the 152 m (500 ft)
building under consideration, a total of eight 0.746 kw fans would be
required. To provide airflow in a racetrack shaped pattern (Figure 3.3),
two 0.91 m, 0,373 kw (36 in., 0,5 h.p.) fans also would be necessary to
provide cross airflow at each end of the building.
Based upon reported data (5), the anticipated quantity of dried manure from
this system (30,000 birds) should be approximately 1315 m3 (46,500 ft3) per
year, This is based on a density of 32 kg/m3 (20 lb/ft3). Density as
accumulated should be higher but decreases due to handling.
As previously discussed (Chapter 3), high-rise, undercage drying necessitates
the construction of a two story structure as opposed to a conventional single
story poultry house. It also requires construction of a floor system to
support the cages and to provide aisles between the cage rows. In this design,
a concrete floor in the manure storage area was included to facilitate manure
removal. Although many high-rise houses have been constructed with a compacted
earthen or cinder base, experience indicates that the use of a concrete floor
is desirable.
157
-------
6.3.1.2 Undercage Oxidation Ditches
The aeration system for this cost analysis was designed as a batch system
with a system volume of 30 Ł/bird (8 gal./bird). The system was Designed
to provide 70 days storage with a maximum mixed liquor total solids (MLTS)
concentration of 45 gm/ a. The carbonaceous oxygen demand for this system
has a maximum estimated value of 415 gm 02/1000 bird-hr or 12.45 kg O^/hr for
30,000 hens. To meet this oxygen demand at a MLTS concentration of 45 gm/&,
an aeration capacity of 21 kg 0?/hr is necessary due to the decrease in oxygen
transfer efficiency with an increase in MLTS concentration (Table 5.4 ). The
volume of stabilized waste requiring ultimate disposal for this system will
be 156 Ł/bird or 4680 m3(165,251 ft3) per year.
6.3.2 Cost Analysis
Each waste management system was divided into four components to simplify
cost analyses. They are facilities costs related to the waste management
system, fixed and operating costs for stabilization equipment, and fixed costs
for handling and disposal of manure. The capital component of annual fixed
costs were determined using an amortization rate of 9% assuming a 20 year
life for structural components and a 10 year life for equipment with no salvage
value. Taxes and insurance were based on a rate of 3 1/2 % of the investment
cost per year. Maintenance costs were assumed to be 1% and 2% of the
respective investment costs for structural components and equipment. A
value of $0.035 per kilowatt-hour was used for the cost of electrical power.
Costs for equipment, such as aeration units, fans, and manure handling
equipment, were obtained from manufacturers or their representatives.
6.3.2.1 Facilities Costs
Both oxidation ditches and high-rise, undercage dyring systems will increase
poultry housing costs above that for a conventional cage type poultry house.
These costs were included in the cost analysis for each waste management
system. Since the high-rise drying system is an integral part of the struc-
ture, total structural costs for a conventional house with manure collection
pits, undercage oxidation ditches, and a high-rise house were compared. Cost
estimates for each, based upon the common criteria presented in Table 6.2,
were obtained from the building department of Agway, Inc., a northeastern
agricultural cooperative (6). Total structural costs for each building and
the waste management component of the costs for oxidation ditches and high-
rise drying are presented in Table 6.3. Based upon the waste management
component of structural costs, annual facilities costs including capital
costs, taxes and insurance, and repairs and maintenance for each alternative
are presented in Table 6.4.
6.3.2.2 Stabilization Costs
In this analysis, stabilization costs were defined as the sum of fixed and
operating costs associated with the operation of aeration units and drying
air circulating fans. Analysis of fixed costs for oxidation ditch aeration
units (Table 6.5), showed a wide variation between manufacturers. The same
158
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TABLE 6,3. ESTIMATES OF THE HASTE MANAGEMENT COMPONENT OF
STRUCTURAL COSTS FOR OXIDATION DITCHES AND
HIGH-RISE DRYING SYSTEMS
Structural Waste Management Component
Costs, $ of Structural Costs, $
Conventional Poultry House
with Manure Collection Pits 144,000
Conventional Poultry House
with Oxidation Ditches 146,500 2,500
High-Rise Poultry House 172,500 28,500
phenomenon was observed in the estimation of operating costs in terms of cost
per kg of oxygen transfer capacity (Table 6.5). These operating cost esti-
mates were based on oxygen transfer capacities and power requirements obtained
from reported research results or from manufacturer's brochures when indepen-
dently developed data was not available.
Comparison of Tables 6.5 and 6.6 revealed that aeration units with high annual
fixed costs had low operating costs. Expressing annual fixed costs in terms
of cost per kg of oxygen transfer capacity and combining this value with
operating costs revealed that there was little difference between 4 of the 5
units evaluated (Table 6.7). Excluding unit B, the average total cost per
kg of oxygen transferred was $0.058. For the aeration system under considera-
tion with a maximum required oxygen transfer capacity of 21 kg 02/hr, the total
annual cost for oxygen transfer was estimated to be $10,524.
As previously noted, the 30,000 bird high-rise system design requires eight
0.746 kw and two 0.373 kw drying air circulating fans. A study of air moving
efficiencies of agricultural propeller type fans such as those used to circu-
late dyring air in a high-rise manure drying system has shown a wide variation
in efficiency between manufacturers (7). Analysis of both annual fixed and
operating costs were based on a maximum reported airflow efficiency of 0.010
m^/sec per watt (21 ft3/sec per watt). For the 10 fans required, the annual
fixed cost was found to be $749 per year based upon initial costs obtained
from vendors. The annual operating cost was calculated to be $2569 per year
at $0.035/kwhr.
6,3.2.3 Handling and Disposal Equipment Costs
The total cost for handling and disposal of manure is perhaps the most dif-
ficult component of total waste management costs to quantify due to the com-
paratively high labor component in comparison to other aspects of these waste
management systems. Trade-offs exist between investment and other fixed costs
159
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TABLE 6.4. ANNUAL WASTE MANAGEMENT FACILITIES COSTS FOR OXIDATION DITCHES
AND HIGH-RISE DRYING FOR A 30,000 BIRD OPERATION
Annual *
Capital Cost, $
g Undercage Oxidation Ditches 274
High-Rise, Undercage Drying 3,125
Taxes &**
Insurance, $
10
109
Repairs1"
Maintenance, $
3
31
Annual
Facilities Costs, $
287
3,265
* Amortized at 9 percent per year over an estimated useful life of 20 years.
**Estimated at the rate of 3.5 percent of initial cost per year.
f Estimated at the rate of 2 percent of initial cost per year.
-------
TABLE 6.5. ESTIMATED ANNUAL FIXED COSTS FOR OXIDATION DITCH AERATION UNITS
•
Manufacturer
A - 1.8m rotor
- 2.4 m rotor
B -
C - 1.8m rotor
D - 3.0 m rotor
Initial
Cost, $
8,170
8,550
1,270
2,610
3,500
Annual*
Capital Cost, $
1,274
1,333
198
407
546
Taxes and**
Insurance, $
286
299
44
91
122
Maintenance^"
and Repairs, $
163
171
25
52
70
Total Annual
Fixed Cost, $
1,723
1,803
267
550
738
* Amortized at 9 percent per year over an estimated useful life of 10 years.
**Estimated at the rate of 3.5 percent of initial cost per year.
+ Estimated at the rate of 2 percent of initial cost per year.
-------
TABLE 6.6. ESTIMATED OPERATING COSTS FOR OXIDATION DITCH AERATION UNITS
Manufacturer
A - 1.8m rotor
- 2.4 m rotor
B -
C - 1 .8 m rotor
D - 3.0 m rotor
Capacity,
gm Op/hr
4857
6457
1244
3360
3110
Power gm Op/
Requirements, kw* kw-hr
2.94
3.94
1.93
3.68
2.98
1652
1644
644
913
1044
Cost/kg 02, $**
.021
.021
.105
.040
.034
* Calculated from net power requirements assuming maximum motor efficiency
of 75%.
**Based upon an electrical energy cost of $.035 per kw-hr.
TABLE 6.7. SUMMARY OF TOTAL COSTS FOR OXIDATION DITCH
AERATION UNIT OXYGEN TRANSFER
Operating*
Manufacturer Cost/kg Op, $
A .021
.021
B .105
C .040
D .034
Annual Equipment
Cost/kg 02, $
.040
.032
.046
.019
.027
Cost/kg 02, $
.061
.053
.151
.059
.061
*Based on 24 hour 360 day operation.
162
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which are related to equipment capacities and operating and labor costs. In
the interest of simplicity, only fixed costs for handling and disposal equip-
ment were considered. Labor and operating costs were evaluated indirectly
in terms of the number of loads of waste per year requiring ultimate disposal
from each system.
A summary of the fixed manure handling and disposal equipment costs associated
with each alternative is presented in Table 6.8. Also included are estimates
of the number of loads of manure requiring ultimate disposal annually based
upon anticipated waste volumes noted earlier and spreader capacities specified
for each system.
TABLE 6.8. COMPARISON OF ANNUAL FIXED MANURE HANDLING AND
DISPOSAL EQUIPMENT COSTS
Oxidation High-Rise
Ditches, $ Drying, $
Initial Cost 6,159* 4,915**
Annual Cost 960 766
Taxes & Insurance 216 172
Repairs & Maintenance 123 98
Total Annual Equipment Cost 1,299 1,036
No. of Loads per year 410 173
* 11.4 m liquid manure spreader loaded by gravity.
**7.6 m box type manure spreader and 75% of a tractor mounted front-end
loader.
For the high-rise drying system, a skid steer or tractor mounted loader for
manure removal from the building is necessary in addition to a box type manure
spreader for transport and disposal. The costs in Table 6 reflect only fixed
costs directly related to a front end loader. It was assumed that 75 percent
of the annual operating time of the loader would be for manure handling.
Since manure handling should represent only a small fraction of the annual
tractor operating time, fixed costs associated with this tractor were omitted.
For the oxidation ditches, it was assumed that the aerated slurry could be
transferred to a manure spreader by gravity. Thus, only a closed, tank type
liquid manure spreader was considered in the estimate of handling and disposal
equipment costs for the oxidation ditch alternative.
163
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6.3.2.4 Discussion
A summary of the component costs for the oxidation ditch and high-rise,
undercage drying systems is presented in Table 6.9. These data show that
managing poultry wastes using oxi^r.' 'c ditches operated as batch reactors
will have a higher cost as compared to high-rise, undercage drying. This is
in addition to higher ultimate disposal requirements (Table 6.8). However,
it should be recognized that these liabilities are due primarily to the
absence of effective liquid-solid separation and solids thickening techniques
which would make operation of continuous flow aeration systems feasible. This
would permit maintenance of MLTS concentrations of less than 20 gm/2, and
reduce high stabilization costs due to the inefficiency of aerating poultry
manure slurries at high MLTS concentrations.
TABLE 6.9. SUMMARY OF WASTE MANAGEMENT COMPONENT COSTS FOR
OXIDATION DITCHES AND HIGH-RISE, UNDERCAGE DRYING
Undercage High-Rise
Oxidation Undercage
Ditches,$ Drying, $
Facilities Costs 387 4,408
Stabilization Costs 10,524 3,318
Manure Handling and
Disposal Equipment Costs 1,299 1,036
Total Annual Waste
Management Costs 12,210 8,762
Both fixed and operating costs would be reduced due to the decrease in oxygen
transfer capacity requirements. A 50 percent reduction of stabilization costs
would be possible. However, this alternative awaits the development of a
practical liquid-solids separation process. Otherwise, the reduction in
stabilization cost will merely be shifted into ultimate disposal costs.
A summary of the unit costs for the two alternative modes of oxidation ditch
operation and for high-rise, undercage drying is presented in Table 6.10.
The costs for the continuous flow mode of oxidation ditch operation do not
include liquid-solid separation costs. Thus, actual costs for the continuous
flow mode of operation with liquid-solids separation will be somewhat higher
due to added fixed and operating costs for this process. However, the poten-
tial exists to reduce ultimate disposal costs if thickening to solids concen-
trations in excess of 45 gm/Ł can be achieved. This would serve to reduce the
high volumetric ultimate disposal requirements which is a major liability of
this waste management approach.
164
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TABLE 6,10. COMPARISON OF POULTRY WASTE
MANAGEMENT UNIT COSTS*
System Cost/1000 Hens/yr, $ Cost/Dozen Eggs,** $
Oxidation Ditch
Batch 407 0.020
Continuous Flow1" 211 0.010
High-Rise, Undercage Drying 292 0.0146
* Excludes labor and operating costs for ultimate waste disposal.
**Assumes 20 dozen eggs per hen-year.
t Excludes liquid-solid separation and thickening costs.
While the costs of both high-rise, undercage drying and aeration of poultry
wastes are comparable, the practicality of these approaches will depend
heavily on economic impact. Since the price the producer receives for eggs
is determined by the market forces of supply and demand, there is no oppor-
tunity to pass on the cost of pollution control measures. The economic impact
of any waste management system on net income is a logical criteria for the
economic assessment of that system.
A 1975 survey (8) of New York State poultry farms showed that labor and
management incomes varied widely. Income ranged from minus values to over
$30,000 per operator. Similar variations were reported in 1974 and 1973
10). Differences in management skills among producers appear to be the major
factor responsible for this variability.
As an alternative, capital investment and production costs were used as base-
lines for economic assessment of these waste management alternatives. This
procedure permitted evaluation of economic impact in terms of efficient pro-
duction resulting from skillfull management. Egg production costs in New York
State for the years 1973-75 are presented in Table 6.11. The values noted are
average values reported for New York State except for feed costs. Feed costs
were based on 1.91 kg (4.2 Ib) of feed per dozen eggs and 20 dozen eggs
marketed per hen-year. The effect of good management is reflected in the
noted feed conversion efficiency and production values which are above average.
The impact of waste management costs for high-rise, undercage drying and
aeration systems on egg production costs for the years 1973-75 are summarized
in Table 6.12. These results indicate that both approaches are economically
feasible. In considering the costs presented in this section, it should be
recognized that these values are for specific system designs. For example,
increasing the cumulative time of batch aeration system operation will reduce
ultimate disposal requirements but increase stabilization costs. Thus,
165
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TABLE 6.11. NEW YORK STATE EGG PRODUCTION COSTS (8, 9, 10)
Cost/Hen-Year ($)
Return to Capital @ 9%
Labor*
Feed1"
Hen**
Building repairs
Electricity
Taxes
Insurance
Total
Production Cost/dozen eggs*f
1975 1974
0.67 0.69
1.17 0.94
5.56 5.73
2.00 2.00
0.02 0.03
0.11 0.10
0.08 0.07
0.09 0.11
9.70 9.67
0.485 0.484
1973
0.67
0.94
5.12
2.00
0.03
0.11
0.07
0.11
9.05
0.453
* Includes Operator's Labor.
+ Based upon 1.91 kg (4.2 Ib) of feed/dozen eggs produced.
**Estimated cost of $2.25/bird
less salvage value of $0.25/bird.
*t Based upon 20 dozen eggs/bird-year.
TABLE 6.12. IMPACT
ON EGG
OF WASTE MANAGEMENT ALTERNATIVES
PRODUCTION COSTS
Sys tern
Oxidation Ditch
Batch
Continuous Flow
High-Rise, Undercage Drying
Percentage Increase In
Egg Production Costs
1975 1974
4.1 4.1
2.1 2.1
3.0 3.0
1973
4.4
2.2
3.2
166
-------
relative costs can not be considered constant but will vary to some degree
with variation in design.
6.4 Plant Nutrient Value
Poultry manure as produced contains nitrogen, phosphorus, and potassium as
well as calcium in significant quantities. In situations where plant nutrients
can be utilized for field crop production or marketed, the ability of a waste
management system to conserve these nutrients is an import consideration.
However, it should be recognized that the value of these nutrients is only
realized when these nutrients are actually utilized in place of purchased
fertilizer inputs. In situations where cropping activities are absent,
conserved plant nutrients have no value unless a market exists. Then, the
real value may be less than equivalent cost as chemical fertilizer due to a
different supply and demand relationship.
Neither high-rise, undercage drying systems nor oxidation ditches operated for
odor control appear to be effective systems for nitrogen conservation. A
nitrogen loss of 53 percent based on mass balance results from a full scale
high-rise, undercage drying system evaluation has been reported (5). The
percentage of nitrogen remaining as ammonia was 37.5 percent. Since
opportunities for volatilization during and following surface spreading are
sizable, the potential for plant utilization of this ammonical nitrogen
appears minimal. Thus, an assumption of a 71 percent nitrogen loss appears
reasonable. This value compares favorably with the value of 69 percent for
the biodegradable fraction of the nitrogen in poultry manure (Chapter 4).
In a study of the relationship between drying rates and nitrogen losses from
poultry wastes, it was observed that the microbial activity responsible for
the transformation of organic nitrogen to ammonia is not restricted until
moisture levels are as low as 20 to 30 percent, wet basis (11). The magnitude
of nitrogen loss was shown to be a function of the drying time to reach the
equilibrium moisture content for poultry wastes, 10 to 15 percent wet basis.
The following empirical relationship relating nitrogen loss to drying time was
developed from laboratory studies.
NL = 77[l _e-°-0032(DT)+0-082] (6.1)
where: NL = nitrogen loss, %
DT = drying time to the equilibrium moisture content
(10 to 15 % wet basis), hours.
In that rapid moisture reduction to low levels is necessary to conserve
nitrogen contained in poultry wastes, high-rise, undercage drying does not
appear to be an effective approach for the conservation of this plant nutrient.
A comparable magnitude of nitrogen loss has also been observed in oxidation
ditches where aeration was limited to odor control requirements (4). Where
levels of oxygen transfer are limited to the exerted carbonaceous oxygen demand,
nitrification will be inhibited and nitrogen losses via ammonia desorption will
167
-------
occur Increasing oxygen transfer to include the nitrogenous oxygen demand
will permit nitrification and minimize nitrogen losses via ammonia stripping.
However, results of pilot plant studies (12) have shown that a 30 percent
loss of nitrogen via denitrification can occur even at high dissolved oxygen
concentrations. Considering the refractory fraction of poultry manure
organic nitrogen, the maximum level of conservation appears to be 39 percent
of the quantity excreted. An analysis of the cost per unit nitrogen conserved
based upon increased oxygen requirements to satisfy the nitrogenous oxygen
demand, the Appendix, Figure A-10, indicates the minimum cost would be $0.47/
kg N($0.21/lb N). Decreased oxygen transfer efficiencies at mixed liquor
total solids concentrations exceeding 20 gm/Ł would increase these costs. At
current prices of $0.47/kg N ($0.20 Ib N) (13), this approach does not appear
to be cost effective. In addition, storage under non-aerated conditions will
result in dentirification due to the availability of organic carbon compounds
even in highly stabilized slurries (14).
The transformations of phosphorus and potassium as well as calcium in either
system have not been clearly delineated. Since these elements do not possess
volatile forms, losses should not occur. Possible chemical transformations
rendering these elements unavailable to plants should be equal in both systems.
Thus, it appears that from a practical standpoint, the plant nutrient value of
manure from high-rise, undercage drying systems and oxidation ditches are
equal. However, it should be noted that both high-rise, undercage drying and
aeration make poultry manure a more acceptable source of plant nutrients as
compared to these wastes in an unstabilized form. This is due primarily to
the reduction of malodors normally associated with these wastes.
Experience indicates that aerated poultry manure can be successfully marketed
as a source of plant nutrients and as a soil conditioner to producers of
vegetable and field crops (15). This material was sold for an average of
$2.60/1000 i ($10.00/gal.) over marketing costs thereby reducing overall
waste management costs. An important aspect of this marketing venture was
the acceptance of this material as a supplement to chemical fertilizer with
farmers repeating purchases for a second year. Although undocumented, a
similar market potential appears to exist for poultry manure from high-rise,
undercage drying systems. It is important to understand that this approach
to ultimate disposal depends on local demand and may vary greatly.
6.5 Refeeding Potential
The recovery of the nutrient value of poultry wastes through refeeding back
to laying hens or to other animal species offers the potential of increased
efficiency in the production of animal products. It is clear that from a
nutritional standpoint the ruminants are the most desirable target species.
This is due to their ability to utilize nonprotein nitrogen. However, the'
logistics of this practice are often undesirable.
Several studies have investigated the potential of refeeding both dried and
aerated poultry wastes to laying hens. Flegal and Zindel (16) have reported
a 3 percent increase in egg production with a diet containing 10 percent
dried poultry manure. At higher levels, egg production was decreased as
168
-------
compared to the control diet. Nesheim (17) reported slightly lower egg
production when dried poultry manure was fed at a level of 22.5 percent. The
economic value of dried poultry manure was due primarily to its high phosphorus
content. This factor along with associated amino acid and energy content made
dried poultry manure a preferred source of phosphorus in comparison to meat
meal and dicalcium phosphate. A 2 percent increase in egg production has been
reported when aerated poultry manure was refed as a substitute for tapwater
(18). No adverse effects were observed in relation to egg quality or bird
health.
In order to refeed poultry wastes from a high-rise, undercage drying system,
additional drying would be necessary. Moisture levels far below those typical
of this drying approach are necessary to permit incorporation into a typical
laying ration and to allow storage without spoilage. A machine type drier
and feed mixing equipment would be required. Thus, the compatability of direct
refeeding with high-rise, undercage drying of poultry wastes appears question-
able. From a practical standpoint, the direct refeeding of aerated poultry
wastes appears to have greater potential. Using the approach of substitution
for tapwater, only a small pump for circulation and a trough type watering
system would be required.
A number of unknown factors remain in the area of refeeding poultry wastes
to laying hens. Thus, the question of refeeding potential should play a very
minor role at present in the selection of a waste management system at this
time.
6.6 References
1. Ludington, D.C., A.T. Sobel, R.C. Loehr, and A.G. Hashimoto. Pilot Plant
Comparison of Liquid and Dry Waste Management Systems for Poultry Manure.
Proc, Agric. Waste Management Conf,, Cornell University, Ithaca, New York.
1972. p. 569-580.
2. Sobel, A.T. Olfactory Measurement of Animal Manure Odor. Paper No.
70-417. ASAE. St. Joseph, Michigan. 1970.
3. Sobel, A.T. and D.C. Ludington. Management of Laying Hen Manure by
Moisture Removal. AWM 75-01. Dept. of Agricultural Engineering,
Cornell University, Ithaca, New York. 1975. 100 p.
4. Martin, J.H. and R.C. Loehr. Demonstration of Aeration Systems for
Poultry Wastes, Environmental Protection Technology Series Report No.
EPA/2-76-186. U.S. Environmental Protection Agency, Washington, D.C.
1976. 151 p.
5. Sobel, A.T. The High-Rise System of Manure Management. AWM 76-01.
Dept. of Agricultural Engineering, Cornell University, Ithaca, New York.
1976. 45 p.
6. Mel lor, C. Production Manager, Building Department, Agway, Inc.
Syracuse, New York. Personal Communication, 1977.
169
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7. Albright, L.D. Air Moving Efficiencies of Ventilating Fans. Paper No.
NA 75-034. ASAE. St. Joseph, Michigan. 1975. 15 p.
8. Bratton, C.A. and G.H. Thacker. 1975 Poultry Farm Business Summary.
A.E. Extension. 76-25. Dept. of Agricultural Economics, Cornell
University, Ithaca, New York. 1976. 32 p.
9. Bratton, C.A. and G.H. Thacker. 1974 Poultry Farm Business Summary.
A.E. Extension. 75-20. Dept. of Agricultural Economics, Cornell
University, Ithaca, New York. 1975. 36 p.
10. Bratton, C.A. and G.H. Thacker. 1973. Poultry Farm Business Summary
A.E. Extension. 74-15. Dept. of Agricultural Economics, Cornell
University, Ithaca, New York. 1974. 34 p.
11. Holmes, B.J. Effect of Drying on the Losses of Nitrogen and Total Solids
from Poultry Manure. Unpublished M.S. Thesis. Cornell University,
Ithaca, New York. 1973. 97 p.
12. Prakasam, T.B.S., E.G. Srinath, A.C. Anthonisen, J.H. Martin, Jr. and
R.C. Loehr. Approaches for Control of Nitrogen with an Oxidation Ditch.
Proc. Agric. Waste Management Conference, Cornell University, Ithaca,
New York. 1973. 97 p.
13. Agway, Inc., Fertilizer Division, Syracuse, New York. Personal
Communication. 1977.
14. Loehr, R.C., T.B.S. Prakasam, E.G. Srinath, T.W. Scott, and T.W. Bateman.
Design Parameters for Animal Waste Treatment Systems - Nitrogen Control.
Environmental Protection Technology Series. Report No. EPA-600/2-76-190.
U.S. Environmental Protection Agency, Washington, D.C. 1976. 144 p.
15. Anthonisen, A.C. and D.H. Wagner. Practical Application of Poultry
Manure. Proc. Agric. Waste Management Conf., Cornell University,
Ithaca, New York. 1977. In press.
16. Flegal, C.J. and H.C. Zindel. Dehydrated Poultry Waste (DPW) as a
Feed in Poultry Rations. In: Livestock Waste Management and Pollution
Abatement. ASAE. St. Joseph, Michigan, 1971. p. 305-307.
17. Nesheim, M.C. Evaluation of Dehydrated Poultry Manure as a Potential
Poultry Feed Ingredient. Proc. Agric. Waste Management Conf., Cornell
University, Ithaca, New York. 1972. p. 301-309.
18. Martin, J.H., Jr., D.F. Sherman, and R.C. Loehr. Refeeding of Aerated
Poultry Wastes to Laying Hens. ASAE. Paper No. 76-4513, St. Joseph,
Michigan. 1976. 11 p.
170
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C HIGH-RISE* UNDERCAGE DRYING: SENSITIVITY ANALYSIS OF
C DESIGN VARIABLES
C AF^AREA FACTOR* DIMENSIONLESS
C MLF=MOISTURE LOADING FACTOR»KG H20/H2-DAY
C AV = AIR VELOCITY, M/SEC
C VPD = VAPOR PRESSURE DIFFERENTIAL* PASCALS
C X=FACTOR
C MTDB = HANURIAL SURFACE MOISTURE CONTENT AT TII^E T,DRY BASIS
C MTWB=MANURIAL SURFACE MOISTURE CONTENT AT TIME T* WET BASIS
1 REAL AF»MLF»AV*VPD»X»MTDB*MTI»'B
C VARIABLE* AREA FACTOR* 0.9-1.6
2 10 R.EAD,KLF,AV»VFD
3 URITE(6*11>
4 11 FORMAT(»1«*40X,*AREA FACTOR RANGE = 0.9 TO !.&*>
5 WRITE(6,12>
6 12 FORMATC* **40X**MOISTURE LOADING FACTOR = 2.72 KG H20/H2-DAYM
7 WRITE(6*13)
8 13 FORMAT(« *,40X*«AIR VELOCITY = 0.5 M/SEC«)
9 WRITEt6*lf>
10 14 FORMATC «*40X,'VAPOR PRESSURE DIFFERENTIAL = 1360 PASCALS*)
11 URITE(6*15)
12 15 FORMAK* * * 47X * • AF • * 7X * • X « * 7X * *HTDF f » 7X * • MTWE * )
13 16 READ,AF
14 IF(AF.EG.-l) GO TO 20
15 CALL CALC(X»AF,MLF*AV*VPD*MTDB*MTWB)
16 WRITE(fc*18) AF*X,MTDE*MTWB
17 18 FORMATC • ,40X ,4F1 0 . 3 )
18 GO TO 16
C VARIABLE* MOISTURE LOADING FACTOR,2.36-1.7k* 7.9~2 . ?
19 20 READ*AF,AV»VPD
20 WRITE(6*21)
Figure A-l. High-rise, undercage drying: sensitivity analysis of
design variables - source listing and data output
-------
21 21 FORMAT(» » , 4 OX, »HO ISTURE LOADING FACTOR RANGE 3.70 TC <-.36 AND 2
*2 TO 2.62 KG H20/M2-DAY*)
22 WRITE<6»22)
23 22 FORMATC *,40X,»AREA FACTOR - 1.3»>
24 WRITE(6,23)
25 23 FORMATC* *,40X,»AIR VELOCITY = 0.5 M/SEC*)
26 WRITE<6*24>
27 24 FORMATt* *,40X,'VAPOR PRESSURE DIFFERENTIAL - 1360 PASCALS')
28 URITE(6»25)
29 25 FORMATC « ,46X , »ML F« , 7X, »X • ,7 X , »MTDB * *7X, « MTWF1-.« )
30 26 READ»MLF
31 IF(MLF.EQ.-l) GO TO 30
32 CALL CALC(X,AF,MLF»AV»VPD»MTDB»MTWB>
33 WRITE(6,28> MLF ,X,MTDB,HTWB
3* 28 FORMATC • »^OX» 4F1 0 . 3)
35 GO TO 26
C VARIABLE* AIR VELOCITY, SOO-54CO
36 30 READ»AF»MLF,VPD
37 URITE(6,31)
38 31 FQRMATC* «»40X»*AIR VELOCITY RANGE = .01 TO 2.0 M/SECM
39 URITE(6»32)
40 32 FORMAT(* f.40X»»AREA FACTOR = 1.3*)
41 WRITE(6»33)
42 33 FORMAT(» * »40 X , »MO ISTURE LOADING FACTOR = 2.72 KG H20/K>2-D AY * )
43 WRITE(fe»34>
44 34 FORMAK* •»40X»«VAPOR PRESSURE DIFFEREMTIAL = 1360 PASCALS*)
45 WRITE(fc»35>
46 35 FORMAT(* •»47X,«AV • »7X , •X•*7X , »MTD3»»7X,•MTWB*>
47 36 READ.AV
48 IF(AV.EQ.-l) GO TO 40
49 CALL CALC(X,AF, MLF , A.V « VP D» MTDB ,KTWB)
50 WRITE(6»38) AV,X.MTDB*MTWB
51 38 FORMATC * » 40 X , 4F1 0 . 3 >
Figure A-l. (Continued)
-------
52 60 TO 36
C VARIABLE* VAPOR PRESSURE DIFFERENTAL, 340-2720
53 40 READ,AF,MLF,AV
54 URITE<6t41>
55 41 FORMATC *»40X,'VAPOR PRESSURE DIFFERENTIAL RANGE = 100 TO 2700 PA
*SCALS«)
56 WRITE(6»42>
57 42 FORMATC* «*40X»*AREA FACTOR = 1.3»>
58 WRITE<6,43>
59 43 FORMATC •»40X*«MOISTURE LOADING FACTOR = 2.72 KG H20/M2-DAY»)
60 WRITE<6»44>
61 44 FORMATC »»40X»»AIR VELOCITY r 0.5 H/SEC»>
62 WRITEC6,45)
63 45 FORMATC* •»45X.,*VPD«»8X,*X*,7X»*RTDB*t7X,«MTWB»)
64 46 READ»VPD
55 IF(VPD.EG.-l) GO TO 50
66 CALL CALC
67 URITE{6,48> VPD»X»MTDB»MTW3
68 48 FORMATC » «40X * 4F1 0 .3 )
69 GO TO 46
70 50 STOP
71 END
72 SUBROUTINE CALC (X» AF *MLF »A V « VPD »MTDB »MTU'B >
73 REAL X,AF»MLF,AV»VPD*f'TDB»MTWB
74 X=(AF/MLF)*AV*VPD
75 MTDB=2271*(X**C-.494>)
76 MTWB=100*MTDB/(100+MTDB)
77 RETURN
78 END
Figure A-l. (Continued)
-------
AREA FACTOR RANGE - 0.9 JO 1.fc
MOISTURE LOAD IMG FACTOR = 2.72 KG H2C/M2-QAY
AIR VELOCITY = 0.5 M/S EC
VAPOR PRESSURE DIFFERENTIAL = 1360 PASCALS
AF
0.900
1.000
1.100
1.200
1.300
1.400
1.500
1.600
X
225.000
250.000
275.000
300.000
325.000
350.000
375.000
400.000
KTD6
156.401
148.46°
141.640
135.681
130.421
125.733
121.51?
117.706
M T W B
60.999
59.753
58.616
57.570
56.601
55.700
54.857
54.067
MOISTURE LOADING FACTOR RANGE'3.70 TO 4.36
AND 2.22 TO 2.62 KG H20/M;
AREA FACTOR = 1.3
AIR VELOCITY = 0.5 M/SEC
VAPOR
PRESSUR
MLF
4.360
4.25C1
4.14C
4.030
3.920
3.810
3.700
2.620
2.520
2.420
2.320
2.220
E DIFFER
X
202.752
208.000
213.527
219.355
225.510
232.021
238.919
337.405
350.793
365.289
381.034
398.198
ENTIAL = 1
i^TDB
164.655
162.590
160.497
158.376
156.226
154.045
151.831
128.030
125.592
123.105
120.565
117.969
360 PASCALS
M T W B
62.215
61.918
61.612
61.297
60.972
60.637
60.291
56.146
55.672
55.178
54.662
54.122
Figure A-l, (Continued)
-------
AIR VELOCITY RANGE = .01 TO 2.0 M/SEC
AREA FACTOR = 1.3
MOISTURE LOADING FACTOR = 2.72 KG H20/M2-DAY
VAPOR PRFSSURE DIFFERENTIAL = 1360 PASCALS
iV
C.01C
0.250
0.500
0 . 7 5 D
1 .000
2 . 0 0 &
X
Ł.500
162 . 500
325. OCO
4 8 7 . * 0 0
650.000
1300.000
•UDF
900 .820
183.677
130.^21
1 0 Ł . 7 4 7
92.606
65.755
HTWB
9 0 . 0 0 P
64.749
56.601
51.632
48.080
35.670
VAPOR PRESSURE DIFFERENTIAL RANGE = 100 TO 27CO PASCALS
AREA FACTOR - 1.3
MOISTURE; LOADING FACTOR = 2.12 KG HZC/MS-DAY
R VELOCITY
VPD
100.000
340.000
680.000
1020.000
1360.000
1700.000
2040.000
2380.000
2720.000
= 0.5 M / S E
X
23.897
81 .250
162.500
243.750
325.000
406.250
487.500
568.750
650.000
C
MTD3
473.494
258. 6R1
183 .677
150.337
130.421
116.808
106.747
98.920
92.606
MTWB
82.563
72.120
6^.749
60.054
56.601
53.876
51.632
49. 729
48.080
Figure A-l. (Continued)
-------
TABLE A-l. DATA USED FOR DETERMINATIONS OF REFRACTORY AND
BIODEGRADABLE FRACTIONS OF POULTRY MANURE
o\
Parameter
Total Solids
Volatile Solids
Chemical Oxygen
Demand
Organic Nitrogen
SRT,* Days
10.5
15
18
21
27
36.5
10.5
15
18
21
27
36.5
10.5
15
18
21
27
36.5
10.5
15
18
21
27
36.5
S , gm/gm FS**
3.45
3.95
3.45
3.95
3.95
3.95
2.45
2.95
2.45
2.95
2.95
2.95
2.55
2.56
2.55
2.56
2.56
2.56
0.262
0.307
0.262
0.307
0.307
0.307
S-j , gm/gm FS**
2.54
2.41
2.31
2.45
2.55
2.34
1.53
1.45
1.31
1.50
1.54
1.35
1.98
1.72
1.63
1.76
1.76
1.66
0.134
0.138
0.109
0.122
0.108
0.113
VSo
0.74
0.61
0.67
0.62
0.64
0.59
0.62
0.49
0.53
0.51
0.52
0.46
0.78
0.67
0.64
0.69
0.69
0.65
0.51
0.45
0.42
0.40
0.35
0.37
1/(SQ • SRT)
0.028
0.017
0.016
0.012
0.009
0.007
0.039
0.022
0.023
0.016
0.012
0.009
0.037
0.026
0.022
0.01 D
0.014
0.011
0.364
0.217
0.212
0.155
0.121
0.089
*SRT = Solids Retention Time
**FS = Fixed Solids
-------
FIGURE A-2. FLOW DIAGRAM FOR HIGH-RISE, UNDERCAGE DRYING DESIGN
ANALYSIS COMPUTER PROGRAM
Start
/Specify Design Values for
Area Factor and
Vapor Pressure Differential
Specify Design Values for Bird
Density and Initial Manurial
Surface Moisture Content
Read a Value for Moisture
Production per Bird-Day
Calculate Moisture Loading Factor
Calculate Design Drying Air Velocity
Print Moisture Production per Bird-Day,
Moisture Loading Factor, and
Design Drying Air Velocity
1
177
-------
No
No
Have All Values for Moisture
Production per Bird-Day Been Read?
v Yes
Specify Design Values for Initial
Manurial Surface Moisture Content
and Moisture Production per Bird-Day
Read a Value for Bird Density
Calculate Moisture Loading Factor
Calculate Design Drying
Air Velocity
Print Bird Density, Moisture
Loading Factor, and Design
Drying Air Velocity
Have All Values for Bird Density
Been Read?
Yes
178
-------
No
Specify Design Values for Moisture
Production per Bird-Day and
Bird-Density
Read a Value for Design Manurial
Surface Moisture Content
Calculate Moisture
Loading Factor
Calculate Design
Drying Air Velocity
Print Manurial Surface Moisture Content
and Design Drying Air Velocity
Have all Values for Manurial Surface
Moisture Content Been Read?
179
-------
c HIGH-RISE* UNDERCAGE DRYING LLSIGN ANALYSIS
C AF = AREA FACTOR, DI MENSI ONLESS
C VPD = VAPGR PRESSURE DIFFERENTIAL* PASCALS
C MSFDB = MANURIAL SURFACE MOISTURE CONTENT* PERCENT DRY BASIS
C ED = BIRD DENSITY, RIR.DS/M2
C MP = MOISTURE PRODUCTION* GMS h2 C/t: I RL-DAY
C MLF = MOISTURE LOADING FACTOR. KG H20/M2-DAY
C AV = DESIGN DRYING AIR VELOCITY, M/SEC
1 REAL AF,VPD,MSFDB,bD*MPtf'iLfr, AV,W«X« Y,Z
2 READ,AF,VPD
C SIMULATION 0^ THE EFFECT OF VARIATION OF MOISTURE PRODUCTION ON
C DESIGN DRYING AIR VELOCITY
3 WRITE<6,1)
Ł 12 FQRMAT(*0»»5X,»AREA FACTOR = 1.0 */5X,*VAPOR PRESSURE DIFFERENTIA.
° *= 325 PASCALS*/5X,»MANURIAL SURFACE MOISTURE CONTENT = 235 %, CRY
*BASIS*/5X,«6IRD DENSITY - 29.1 BIRDS/M2»)
8 WRITE(6,6)
9 6 FORMAT(* 0 * ,5X,'MOISTURE PRODUCT!CM,•,5X,•MOISTURE LOADING FACTOR,'
*,5X,'DESIGN DRYING AIR'/5X,'GHS H2C /BIRD-DAY',9X , »KG H20/M2-DAY» , i
+6X,'VELOCITY, M/SEC*)
10 7 READ,MP
11 IF(MP.EQ.O)GCT010
12 MLF - (MP/1000)*(BD)
13 AV-EXP«ALCG(MSFDB/2271>)/<-0.49
1^ WRITE(6,8) MP,MLP,AV
15 8 FORMATC * ,1 2X , F5 . 1, 2 3X , F4 . 2 » 2 2X , F ^ . 2 >
16 GO TO 7
C SIMULATION OF THE EFFECT OF VARIATION OF EIPD DENSITY ON DESIGN
Figure A-3. High-rise, undercage drying design analysis - source listing.
-------
C DRYING AIR VELOCITY
17 10 URITE(6»11)
18 11 FORMAT<*0»*5X,'SIMULATION OF THE EFFECT OF VARIATION OF BIRD DENSI
*TY ON DESIGN DRYIMG AIR VELOCITY*)
19 READ,MSFDB*MP
20 WRITE(6fl2>
21 12 FORMAT(*0»»5X*«APEA FACTOR = 1.0»/5X ,»VAPOR PRESSURE DIFFERENTIAL
*= 325 PASCALS»/5X,»MANURIAL SURFACE MOISTURE CONTENT - 235%* DRY 5
*ASIS»/5X**MOISTURE PRODUCTION -
23 14 FQRMATC»0«*5X,«BIRD DENSITY,',12X,*MOISTURE LOADING FACTOR»•*5X , »D
*ESIGN DRYING AIR»/5X»*BIRBS/1^ «* 17X**KG H20/M2-D AY * , lf>X • • VELOC I T Y.
*M/SEC»)
24 16 REAO»BD
25 IF(BD.EQ.O) GO TO 20
26 MLF = -ALOG(AF/MLF>-ALOG
28 URITE<6*18> BD»MLF»AV
29 18 FORMATC * »9X , F4 . 1 * 27X ,F4 . 2 » 22 X , F4 . 2 >
30 GO TO 16
C SIMULATION OF THE EFFECT OF VARIATION OF DESIGN MANURIAL SURFACE
C MOISTURE CONTENT ON DESIGN DRYING AIR VELOCITY
31 20 WRITE(fe»21)
32 21 FORMAT(*0!«5X»•SIMULAT ION OF THE EFFECT OF VARIATION OF DESIGN MAN
*URIAL SURFACE MOISTURE CONTENT ON DESIGN DRYING AIR VELOCITY*)
33 READ«MP,BD
34 WRITE(6»22)
35 22 FORMATC*0»»5X»»AREA FACTOR = 1 . 0 */5X,* VA^OR PRESSURE DIFFERENTIAL
*= 325 PASCALS»/5X»'MOISTURE PRODUCTION = 90.6 C-^S H20/BIRD-OAY •/5X
*,«BIRD DENSITY r 29.1 BIRDS/^2«)
36 WRITE<6«24)
Figure A-3. (Continued)
-------
37 24 FORMAK »0» »5X, »MANURIAL SURFACE! MO 1 STUFF. * « f-X « ' L C SI C-IS; DPYIi^
*X,'CONTENT, % DRY t A S I S * «1 0 X , ' VE.LOC 1 T Y , M/SF.CM
38 26 READiMSFDB
39 IF(MSFDb.EQ.O) GO TO 95
fO MLF = (MP/1000)*(8D)
41 AV=EXP((ALOG(MSFDB/2271))/(-0.45^)-ALOG
-------
FIGURE A-4. FLOW DIAGRAM FOR HIGH-RISE, UNDERCAGE DRYING-
SIMULATION OF SYSTEM PERFORMANCE
C
Start
Read Design Values for Moisture Production
Per Bird-Day, Initial Bird Density and
Design Drying Air Velocity
Does Moisture Production
ion = -1.0? \-
No
Initialize SUMMSF = 0
and SUMBDT = 0
Read Initial and Final Values for
Cumulative Time of Operation
and the Increment
Compute Bird Density
Compute Moisture Loading Factor
3
\/
183
-------
No
Compute Area Factor
Compute Vapor Pressure Differential
Compute Drying Air Velocity
Compute Manurial Surface
Moisture Content, % Dry Basis
Compute Manurial Surface
Moisture Content, % Wet Basis
Compute Average System
Moisture Content
Print Cumulative Time of Operation,
Manurial Surface Moisture Content,
and Average System Moisture Content
Is Incremental Value of Cumulative Time
of Operation the Final Value?
Yes ,,
Stop
184
-------
C HIGH-RISE* UNDERCAGE DRYING--SIMULATION OF SYSTEM PERFORMANCE
1 REAL MP,AV«BDl»BDT»MLFTiAFTfVPDT»XT»MSFDBT,fSFWbT,WAVMSF,SUMMSF,SU
*MBDTfAVSYMCtAVI»AVT
2 INTEGER T
C TrCUMULATIVE TIME OF OPERATION* DAYS
C MP^MOISTURE PRODUCTION* GMS H20/BIRD-DAY A CONSTANT
C 8DI=INITIAL BIRD DENSITY, RIPDS/H2
C BDT=BIRD DENSITY AT T
C MLF=MOISTURE. LOADING FACTOR* KG H20/M2-DAY
C MLFT=MLF AT T
C AF=AREA FACTOR* DIKENSIONLESS
C AFT=AF AT T
C AV=AVERAGE DRYING AIR VELOCITY* M/SEC
c AVI^AVERAGF; INITIAL DRYING AIR VELOCITY* M/SEC
C AVT=AV AT T
C VPD-VAPOP PRESSURE DIFFERENTIAL* PASCALS
C VPDI=VFD AT T
_, C XrAN INTERMEDIATE VALUE
oo c XT-X AT T
3 10 READ»MP,AVI*BDI
4 IF(MP.EG.-l.C) GO TO 99
5 WRITE(fe,ll) MP
6 11 FORMATC«1» ••MOISTURE PR0 DUCT I ON *GMS H2O/Ł IRD-D AY = •,5X*F7 . 3)
7 WRITE(6.12> AVI
8 12 FGRMATC* », 'AVERAGE INITIAL DRYING AIR VELOCITY,M/SEC=•* IX,FB.3)
9 WRITE(fe.l3) 5DI
10 13 FORMAT(* **»INITIAL BIRD DENS ITY»6 IRDS/M2=*,13X *FS.2)
11 SUMMSF=0
12 SUMBDT=0
13 18 DO 34 T=l*361»30
14 BDT=(-0.01+T)+EDI
15
Figure A-5. High-rise, undercage drying: simulation of system performance -
source listing.
-------
16 AFT=1.0+(C.OClo*T)
17 AVT^AVI
18 IF(T.LT.200) GC TO 20
19 IF(T.GE.20C) GO TC 22
20 20 VPDT={2.3*T>+?38
21 GO TO 24
22 22 VPDT=<14.2*T)-2148
23 24 XT=(AFT/MLFT)*AVT*VPDT
24 MSFDPT=2271*(XT**<-Q.494>>
25 MSFWBT = 10Q*MSFDBT/<1CG+N'SFDBT>
26 WAVMSF=MSFWBT*BDT
27 SUMMSF=SUMMSF*WAVMSF
28 SUMBDT^SUMBDT-t-BDT
29 AVSYMC=SUMMSF/SUMSDT
-^ 30 WRITE(fcf30) T
cr> 31 30 FORHAK »0* .5X .'CUMULATIVE TIME OF OPERATION T« DAYS =*tI14)
32 WRITE(fc»32) MSFWBT
33 32 FORMAT** » ,5X » *MAM URIA L SURFACE MOISTURE CONTENT AT T, % U'.B.-*«F5
*.!>
34 WRITE(6«33) AVSYHC
35 33 FORMAT(* *t5X,»AVERAGE SYSTEM MOISTURE CONTENT AT T» % W.B.=«fF8.1
*)
36 34 CONTINUE
37 GO TO 10
38 99 STOP
39 END
Figure A-5. (Continued)
-------
FIGURE A-6. FLOW DIAGRAM FOR BATCH MODE AERATION
SYSTEM PROCESS DESIGN
Start
/ Read
- Kinetic Constants A, B, and R
- Raw Waste Characteristics
- Number of Birds
Read System Volume per Bird
ntead Day of Operation
Compute SRT
Is SRT> 10?
No
„ Yes
Compute
Residual Waste Characteristics, S-|
Removal Percentages
187
-------
Is S, < the Refractory Fraction R
for any Characteristic?
Yes
No
S1 = R
Compute Mixed Liquor
Total Solids Concentration
Print
Raw Waste Characteristic
Day of Operation
Residual Waste Characteristics
Removal Percentages
Mixed Liquor Total Solids Concentration
Compute
- Carbonaceous, Nitrogenous, and Total Oxygen
Demand
- Alpha
- Carbonaceous, Nitrogenous and Total Aeration
Requirements
Print
- Carbonaceous, Nitrogenous, and Total Oxygen
Demand
- Alpha
- Carbonaceous, Nitrogenous, and Total Aeration
Requirements
4
V
188
-------
No
Have All Values for Day of
Operation Been Read?
,,Yes
No
/ Have All Values for System
Volume per Bird Been Read?
Yes
C Stop J
189
-------
C LINEAR REGRESSION REMOVAL RELATIONSHIPS-BATCH MODEL
1 REAL ATStAVS*ACOC»AGN»E>TS*&VS»cCCD*BON»RTS«RVS»RCOD*RCN»TSSO*VSSO*
*CODSO»ONSO»NEIRDS«VOLED.DAYOPR.MLTStCAREOD»l\iOD*TOD.ALF-HA*CG2RE:G.NO
*2REQ»T02REQ*TSPC?VSPC.CODPC,CNPC
C TS = TOTAL SOLIDS
C VS = VOLATILE SOLIDS
C COD = CHEMICAL OXYGEN DEMAND
C ON = ORGANIC NITROGEN
C SO = RAW WASTE QUANTITY* GM/BIRD-DAY
C SI = RESIDUAL WASTE. FRACTION* GM/BIRD-DAY
C SOR = REFRACTORY WASTE FRACTION, GM/BIRD-DAY
C PC = PERCENT
C SRT = SOLIDS RETENTION TIME* DAYS
C MLTS = MIXED LIQUOR TOTAL SOLIDS CONCENTRATION* GM/L
C N8IRDS = NUMBER OF BIRDS
C CARBOD = CARBONACEOUS OXYGEN DEMAND* GM 02/HR
C NOD = NITROGENOUS OXYGEN DEMAND* GM 02/HR
C TOD = TOTAL OXYGEN DEMAND* GM 02/H*
C C02REQ = CARBONACEOUS OXYGENATICN REQUIREMENTS. GM 02/HR
C N02REQ = NITROGENOUS OXYGENATICN REQUIREMENTS* GM 02/HR
C T02REQ = TOTAL OXYGENATIOM REQUIREMENTS* SV 02/HR
C VOLBD = VOLUME PER BIRD* L/BIRD
C DAYOPR = CUMULATIVE TIME OF OPERATION. DAYS
C READ KINETIC CONSTANTS
2 1 READ»ATS*AVS*ACOD,AO!\i*BTS*BVS»BCCD»BON*RTS*RVS»RCOD*RON
3 WRITE(6»2>
4 2 FORMAT<»-**24X,'FIXED CONSTANT VALUES*)
5 WRITE(6*3>
6 3 FQRMATC*0**«PARAMETER*»12X*'A VALUES«, 2X*«B VALUES*,2X,*R VALUES')
7 WRITE<6»4> ATS*BTS»RTS
8 4 FORMAT(*0**»TOTAL SOL IDS«* 4X*F10.3.F11.3*F9.3)
9 WRITE(6»5) AVS»BVS*RVS
Figure A-7. Batch aeration system design program - source listing.
-------
10 5 FORMATC «, 'VOLATILE SOL IDS',1X,F1G.3,Fl1.3«FS.3>
11 WRITE(6,6> ACOD»BCOD»PCOD
12 6 FORMAK* • » 'COD • » 1 3X »F 10 .3 *F11 . 3 » F9 . 3 )
13 WRITEC6,?) AON,BGN,RON
1* 7 FORMATC *,'ORGANIC NITROGEN« ,F10.3,Fl1.3»FS.3)
C READ RAW WASTE CHARACTERISTICS EXPRESSED AS GMS/BIRD-DAY
15 10 READ»TSSO,VSSO,CODSO»ONSO
16 WRITE(fc»ll)
17 11 FORMATC-* ,*RAW WASTE CHARACTERISTICS* G MS/B I RD-DA Y * )
18 WRITE(6»12) TSSO
19 12 FORMAT(fO»»»TOTAL SOLI DS*»7X*F6.3>
20 WRITE<6»13> VSSO
21 13 FORMATC *,'VOLATILE SOL I D S « * 4X « F6 . 3 >
22 WRITEC6,14> CODSO
23 14 FORMATC * t ' COD « * 1 6X , F fe . 3)
24 URITE<6tl5> ONSO
25 15 FORMATC «,'ORGANIC NITROGEN»,3X»F6 . 3)
C READ NUMBER OF BIRDS
26 READ,NBIRDS
27 WRITE(6,16) NBIRDS
28 16 FORMAT(«0','NUMBER OF BIRDS* *5X , F10 . 0)
C READ SYSTEM VOLUME/BIRD* LITERS/BIRD
29 20 READ,VOLBD
30 IF(VOLBD.EQ.O) GO TO 99
31 WRITE(6»22> VOLBD
32 22 FORMAK'-*» 'SYSTEM VOLUME/BIRD* LITERS/6IRD»»F10 .1 >
33 24 READ,DAYCPR
34 IF(DAYOPR)20*24»26
35 26 SRT=DAYOPR/2
36 IF(SRT.GT.9.99) GO TO 30
37 GO TO 24
38 30 CALL CALC {ATS,6TS»TSSO,TSS1,RTS»TSPC,SRT»TSSOR,TSPCB>
Figure A-7. (Continued)
-------
39 CALL CALC (AVS»BVS»VSS0 *VSS1»RVS*VSPC»SRT*VSSOR»VSPCB)
40 CALL CALC ( ACOD» BCGD. CCDSG * CGDS1 * RC'CD* CGDPC* SR T * CO DSOR * CODPSC )
41 CALL CALC (ACN*BOM*ONSO*ONSl*RGf\!,Gf-.PC,SRT,GNSOR*ONJPCB)
42 WRITECG,32)
43 32 FORMAT<*-**5X, »DAY**5X,» TOTAL SOLIDS *»4X,» VCLATI
*LE SOLIDS »»*X,» COD »**X* » ORGANIC
* NITROGEN «>
44 WRITE(6«33>
45 33.FORMATC **6X*»OF»>
46 WRITE<6*34>
47 34 FORMAT<» •»2X*•OPERATI ON** 4<5X*»SO * *8X,•SI»*?X,•% REMOVAL1))
48 WRl'TE<6*35>DAYOPR»TSSO,TSSliTSPCtVSSOtVSSl,VSPC»COCSO,CODSl»CODPC»
*OMSO»ONS1< GNPC
49 35 FORMAT(/13F10.3)
C CALCULATE MIXED LIQUOR TOTAL SOLIDS CONCENTRATION
50 40 MLTS=(TSSO*DAYOPR*(1-TSPC/1QQ»/VCLBD
51 URITE(6,41)MLTS
52 41 FORMAT(f0»«»MIXED LIQUOR TOTAL SOLIDS CONCENTRAT ION,GMS/LITER»,5X,
*F10.1)
C CALCULATE MICROBIAL OXYGEN DEMAND»GMS G2/HR
53 42 CARBCD=(CODSO*NBIRDS*CODPC/100)/24
54 NOD=((ONSO*NBIRDS*ONPC/lGC)/24)*4.t57
55 TOD=COD+NOD
56 WRITE(fc»44)
57 44 FORMATC »0» »»f!ICRQBIAL OXYGEN DEMAND AND AERATION REQUIREMENTS*)
58 WRITE(6»45) CARBOD
59 45 FORMATCO* »'CARBONACEOUS OXYGEN DEMAND* GHS G2/HR • , Fl C . 1 )
60 WRITE<6»46) NGD
61 4fc FORHAT<» ».*NITROGENOUS OXYGEN DEMAND* GMS 02/HR»,IX,Fl0.1)
62 WRITE(6»47) TOD
63 47 FORMATC* **«TOTAL OXYGEN DEMAND* GHS 027HR•*6X,F10.i)
C CALCULATE AERATION REQUIREMENTS
Figure A-7. (Continued)
-------
64 IF(MLTS.LE.20>
65 IF(MLTS.GT.20.AND.MLTS.LT.55> ALPHA=<1.36-(.017*MLTS)>
66 IF(MLTS.GE.55) ALPHA=0.4
67 WRITE(6»50) ALPHA
68 50 FORMATC • t • ALPHA * » 32X * F10 . 2 )
69 C02REQ=CARBOD/ALPHA
70 N02REQ-NOD/ALPHA
71 T02REQ=TOD/ALPHA
72 URITE<6,51> C02REQ
73 51 FORMATt*0*»*CARBOMACEOUS OXYGEN REQUIREMENTS* GMS 02/HR•»3X,F10.1>
74 URITE(6»52> N02REQ
75 52 FORMATC * ,*N I TROGENOUS OXYGEN REQUIREMENTS, GMS 02/HR » »4 X ,F1 0 . 1)
76 WRITE(6»53) T02REQ
77 53 FORMATC 't'TOTAL OXYGEN REQUIREMENTS* GMS 02/HR * » 1 0 X , F 1 0 . 1 >
78 GO TO 24
79 99 STOP
80 END
C SUBROUTINE TO CALCULATE % REMOVAL AND EFFLUENT CHARACTERISTICS
81 SUBROUTINE CALC < A »B » SO « SI »R »PC t SRT »S QR» => CP >
82 REAL A,B,SO,Sl»RiPC,SRT»SORfPC5
83 PC=A*SRT-»-B
84 S1=SO*(1-PC/100)
85 SOR=SO*R
86 IF(Sl.LT.SOR) Sl-SOR
87 PCB=(100-(R*100))
88 IF(PC.GT.PCB) PC=PCB
89 RETURN
90 END
Figure A-7. (Continued)
-------
FIGURE A-8. FLOW DIAGRAM FOR CONTINUOUS FLOW MODE
AERATION SYSTEM PROCESS DESIGN
2
V
( Start J
Read
Kinetic Constants A, B, and R
Raw Waste Characteristics
Number of Birds
Read SRT
Is SRT 110?
No
„ Yes
Compute
Residual Waste Characteristics,
Removal Percentages
•>
Is S-j
-------
/\
Print
- SRT
- Raw Waste Characteristics
- Residual Waste Characteristics
- Removal Percentages
/ Read Mixed Liquor
Total Solids Concentration
Compute
Carbonaceous, Nitrogenous, and Total
Oxygen Demand
Alpha
Carbonaceous, Nitrogenous, and Total
Aeration Requirements
Print
Carbonaceous, Nitrogenous, and Total
Oxygen Demand
Alpha
Carbonaceous, Nitrogenous and Total
Aeration Requirements
Compute
- System Volume
- Flow Rate
195
-------
Print
System Volume
Flow Rate
No
Have All Values for
SRT Been Read?
Yes
196
-------
C LINEAR REGRESSION REMOVAL RELATIONSHIPS-CONTINUOUS FLOW MODEL
1 REAL ATS»AVS»ACOD»AON»BTSfBVS»6COD«BON»RTS»RVS»RCOD»RCN»TSSO»VSSC»
*CaDSD»ONSO,TSSl,VSSl»CODSl,ONSl,TSPC,VSPC»CODPC,ONPC«SRT,TSSOR«VSS
*QR,CODSOR,GNSOR»TSPC8,VSPCBfCODPCB.ONPCB,NBIBDS,MLTS,CAR80D,NOD«TC
*D f ALPHA ,SVOL»C02REG,N02REG,T02REQfFLORTE
C TS = TOTAL SOLIDS
C VS = VOLATILE SOLIDS
C COD = CHEMICAL OXYGEN DEMAND
C ON = ORGANIC NITROGEN
C SO = RAW WASTE QUANTITY* GM/RIRD-DAY
C SI = RESIDUAL WASTE FRACTION, GM/BIRD-DAY
C SOR = REFRACTORY WASTE FRACTION* GM/EIFC-DAY
C PC - PERCENT
C SRT = SOLIDS RETENTION TIME, DAYS
C MLTS = MIXED LIQUOR TOTAL SOLIDS CONCENTRATION, GM/L
C NBIRDS = NUMBER OF BIRDS
C CARBOD = CARBONACEOUS OXYGEN DEMAND, GM 02/HR
C NOD = NITROGENOUS OXYGEN DEMAND, GM 02/hR
C TOD = TOTAL OXYGEN DEMAND, GM 02/HR
C C02REQ = CARBONACEOUS OXYGENATION REQUIREMENTS, GM 02/HR
C N02REQ = NITROGENOUS OXYGENATION REQUIREMENTS* GM 02/hR
C T02REQ = TOTAL OXYGENATION REQUIREMENTS, GM 02/HR
C SVOL = SYSTEM VOLUME, L
C FLORTE = FLOU RATE, L/DAY
C INTRODUCTION OF CONSTANTS
2 1 READ,ATS,AVS,ACOD,AON,BTS,BVS,BCOD,BON,RTS,RVS,RCOD,RON
3 WRITE(6,2)
4 2 FORMATCO* ,24X , *FIXED CONSTANT VALUES')
5 WRITE(6,3)
6 3 FORMAT(«0*,»PARAMETER*,12X, ' A VALUES*,2X,*B VALUES*,2X,»R VALUES*)
Figure A-9. Continuous flow aeration system design program - source listing.
-------
7
8
9
10
11
12
13
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
1
1
1
1
1
4
5
6
7
0
1
2
3
4
15
1
2
6
0
WRITE
IDS
3)
*.4X,Ffc.3>
OGEN* »3X.Ffe.3)
RDS
16)
0
t
IF(SRT.EQ.
IF(SRT.GE
25
READ,SRT
•
IFCSRT.NE.
3
0
GO TO 20
CALL CAL
C
CALL CALC
CALL CALC
, t
0)
10
99
-------
38 CALL CALC
40 40 FORMATC*-* »5X»»SRT»»5Xt» TOTAL SOLIDS *»4X," VOLATI
*LE SOLIDS *,4X,» COD *»4X,» ORGANIC
* NITROGEN »)
41 URITE<6»41)
42 41 FORMAT{*0*»9X,4{5X t • SO « ,8X , »S1 • , 5X , • Jf REMOVAL'))
43 WRITE<6»50)SRTfTSSO.TSSl.TSFC*VSSO»VSSlfVSPC»CODSO,COQSl«CODPC»CNS
*0 »ONS1«ONPC
44 50 FORMAT(/13F10.3)
45 SO READ,MLTS
46 IF/24)*4.57
49 TOD=COD+NOD
C CALCULATION OF OXYGEN REQUIREMENTS
50 IFCMLTS.LE.20) ALPRA=1
51 IFCMLTS.GT.20.AND.MLTS.LT.55) ALPHA=(1.36-(.017*MLTS»
52 IFCMLTS.GE.55) ALPHA~C.4
C GXYGE'NATION REQUIREMENTS. CMS C2/HR = 02REG
53 C02REQ=CARBOD/ALPHA
54 N02REQ=NOD/ALFHA
55 T02REQ-TOD/ALPHA
C CALCULATION OF SYSTEP^ VOLUME «L I TERS
56 SVOL=C
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61 64 FORMATt* »»•ALPHA»»3OX»F10.2>
62 WRITE(6, 68)
63 68 FORMAT(•-«»*MICROBIAL OXYGEN DEMAND AND AERATION REGUIKEMENTS•)
64 WRITEC6*70) CARBOD
65 70 FORMATC *C« * 'CARBONACEOUS OXYGEN DEMAND* QMS 02 /H R * * r 1 0 . 1 )
66 WRITEC6*71> NOD
67 71 FORMATC* » » *N IT ROGENOL S OXYGEN DEMAND»GMS U2/HR • « 1 X . Fl C . 1 )
68 WRITE(fe»72> TOD
69 72 FORMATC* »»«TOTAL OXYGEN DEMAND»GMS 02/HR•»gX»F10.1)
70 WRITE(6,73) C02REQ
71 73 FORMATC»0* .'CARBONACEOUS OXYGEN REQUIREMENTS* GMS 02/HP»»3X,Fl0 .1)
72 WRITE(fc»74) N02REQ
73 74 F-ORMATC* • , »N I TROGENOUS OXYGEN REQUIREMENT?* GMS Q2/HR » » 4X ,Fl 0 . 1)
74 WRITEC6,75) T02REQ
75 75 FORMATC* »**TOTAL OXYGEN REQUIREMENT* GMS C2/HR* * 10X,F10.D
76 WRITEC6*76) SVOL
77 76 FORMATC* ***SYSTEM VOLUME*LITERS* *8X,F10.1)
78 WRITEC6,78) FLORTE
79 78 FORMATC* »* *FLOWRATE*LITERS/DAY* *9X*Fl0.1>
o 80 GO TO 60
0 81 99 STOP
82 END
C SUBROUTINE TO CALCULATE % REMOVAL AND EFFLUENT CHARACTERISTICS
83 SUBROUTINE CALC ( A,S,S0 , SI *R , FC,SRT, SOR, PCB>
84 REAL A»B*SO»S1»R»PC»SRT»SOR»PCB
85 PC = A*SRT.-»-B
86 S1=SO*C1-PC/100)
87 SOR=SO*R
88 IFCS1.LT.SOR) S1=SOR
89 PCB=C100-(R*100))
90 IFtPC.6T.PCB) PC=PCE
91 RETURN
92 END
Figure A-9. (Continued)
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FIGURE A-10. COST OF NITROGEN CONSERVATION WITH AERATION
SYSTEMS FOR POULTRY WASTES
Assumptions^
A. Nitrogen excreted = 1.94 gm/ bird -day
B. Maximum potential for nitrogen conservation = 39%
C. Cost of oxygen transfer = $0.058/kg 02
D. Nitrogenous oxygen demand = 255 gm 02/1000 bird-hours at
69 percent organic nitrogen removal
E. Uncontrollable nitrogen loss with nitrification = 30 percent
Quantity of Potentially Conservable Nitrogen per 1000 Bird-days
Fird-dayN x 100° birds x °-39 = 757 9m N/1000 bird-day
Aeration Cost to Meet. the Nitrogenous Oxygen Demand
0.255 kg 0? 24 hr $0.058 _ *n ocr/1nnn hirri d{W-
1000 Bird-hr x ~DiF x T~0 ' 50-355/1000 bird-days
Cost per Unit Nitrogen Conserved
$0.355/1000 bird-days
0.757 kgN/1000 bird-days
201
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-77-20^
I. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
POULTRY WASTE MANAGEMENT ALTERNATIVES: A Design and
Application Manual
5. REPORT DATE
October 1977 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J.H. Martin and R.C. Loehr
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Agricultural Engineering
Cornell University
Ithaca, NY 14853
10. PROGRAM ELEMENT NO.
1HB617
11. CONTRACT/GRANT NO.
R803866-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory - Athens, GA
Office of Research and Development
U.S. Environmental Protection Agency
Athens, GA 30605
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/01
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Changes inthe egg production industry during the past 29-30 years have produced
waste management problems which threaten both water and air quality. Results from
a number of research studies have identified two processes—aerobic biological
stabilization and drying—that provide both odor control and the reduction of the
water pollution potential of these wastes.
In this manual, the theoretical concepts underlying each poultry waste manage-
ment approact are discussed, and process design methodologies are presented. Included
are design examples to illustrate the application of design methodologies. A discus-
sion of the impact of design decisions on performance characteristics and computer
programs to assist in the process design for each alternative are also presented.
Both high-rise, undercage drying and aeration systems are compared to identify
relative merits and provide economic projections. Odor control and plant nutrient
conservation capabilities as well as refeeding potential for both alternatives are
discussed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Poultry manure characteristics, odor
control, drying, biological oxidation,
waste stabilization, capital costs,
operating costs
Poultry manure waste
management, high-rise,
undercage drying, oxi-
dation ditch, process
designs
68D
98C
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)'
ECURITY CLASS (Th
UNCLASSIFIED
21. NO. OF PAGES
216
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
202
*U.S. GOVERNMENT PRINTING OFFICE: 1977— 7 57-140/6580
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