EPA-600/2-76-186
October 1976
Environmental Protection Technology Si ies
                       DEMONSTRATION OF  AERATION
                    SYSTEMS FOR  POULTRY WASTES
                                      Office of Research and Development
                                     U.S. Environmental Protection Agency
                                             Athens, Georgia 30601

-------
                 RESEARCH REPORTING SERIES

 Research reports of the Office of Research and Development, U.S. Environmental
 Protection  Agency, have been grouped into five series. These  five broad
 categories were established to facilitate further development and application of
 environmental technology. Elimination of traditional grouping was consciously
 planned to foster technology transfer and a maximum interface in related fields.
 The five series are:

     1.     Environmental Health Effects Research
     2.     Environmental Protection Technology
     3.     Ecological Research
     4.     Environmental Monitoring
     5.     Socioeconomic  Environmental Studies

 This report has  been assigned  to the ENVIRONMENTAL PROTECTION
 TECHNOLOGY series. This series describes research performed to develop and
 demonstrate instrumentation, equipment, and methodology to repair or prevent
 environmental 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.

-------
                                             EPA-600/2-76-186
                                             October 1976
      DEMONSTRATION OF AERATION SYSTEMS
             FOR POULTRY WASTES
                      by

                 J. H. Martin
                 R. C. Loehr
               Cornell University
            Ithaca, New York 14853
            Project Number S800863
                Project Officer

                Lee A. Mulkey
Technology Development and Applications Branch
       Environmental Research Laboratory
            Athens, Georgia  30601
       ENVIRONMENTAL RESEARCH LABORATORY
     OFFICE OF RESEARCH AND DEVELOPMENT
    U.S. ENVIRONMENTAL PROTECTION AGENCY
            ATHENS, GEORGIA  30601

-------
                              DISCLAIMER


     This report has been reviewed by the Athens Environmental  Research
Laboratory, US Environmental Protection Agency, and approved for
publication.  Approval does not signify that the contents necessarily
reflect the views and policies of the US Environmental Protection Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
                                     11

-------
                               ABSTRACT

A full scale study demonstrated the potential of aeration systems to
reduce the water and air pollution potential of poultry wastes under
commercial conditions.  The performance of two oxidation ditches, each
receiving the wastes from approximately 4000 laying hens, was monitored
and evaluated.

The relationships between two design and operational  variables and
system performance were examined.  The variables were level  of oxygen
supply and solids retention time.  It was observed that an oxygen input
equivalent to the exerted carbonaceous oxygen demand  provided a high
degree of odor control.  Increase in oxygen supply to also satisfy the
exerted nitrogenous oxygen demand resulted in nitrification which terminated
ammonia desorption.  Subsequent nitrogen losses were  the result of de-
nitrification relationships between removals of total solids, volatile
solids, COD, and organic nitrogen in aerated poultry  wastes were
developed.

Two major problem areas were identified and examined.  The first was
the removal and concentration of residual solids to maximize oxygen
transfer efficiency and minimize the volume of material requiring
ultimate disposal.  The second was sedimentation of solids in the oxida-
tion ditch channel which reduced and in several instances stopped mixed
liquor circulation.

The economics in terms of capital and operating costs of these systems
were evaluated.  Results indicated that the total cost of aeration would
have increased egg production costs by a maximum of 4.9 percent in 1973.

This report was submitted in fulfillment of Project Number S800863 by
Cornell University for Manorcrest Farms under the sponsorship of the
Environmental Protection Agency.  Work was completed December 1975.

                                     iii

-------
                               CONTENTS

                                                                 Page
Abstract                                                            iii
List of Figures                                                   vħ
List of Tables                                                      ix
Acknowledgements                                                    xii
Sections
I         Conclusions                                               1
II        Project Need and Objectives                               3
III       Theoretical Considerations                                7
IV        Investigative Facilities, System                         27
            Design and Construction
V         Methods and Materials                                    47
VI        System Performance Results                               56
VII       Discussion of Experimental Results                      113
VIII      References                                              138
IX        Appendices                                              146

-------
                            LIST OF FIGURES
No.                                                              Page

  1         Removal characteristics of total COD and suspended
           solids - semi-logarithmic plot (11)                      9

  2         Relationship between a and mixed liquor total  solids
           concentration in aerated poultry wastes (37)            25

  3         Aeration requirements in relation to mixed liquor
           total solids and CL (37)                                26

  4         Location and site plan of Manorcrest Farm No.  2         28

  5         Plan view, Building No. 1, before modification          29

  6         Cross section, A-A', Building No. 1                     30

  7         Floor plan and analytical laboratory in the Cornell
           Agricultural Waste Management Laboratory                33

  8         Plan view of oxidation ditches and settling tanks       35

  9         Location of velocity measurements, plan view            49

10         Location of velocity measurements, cross section        49

11         Comparison of oxygen transfer characteristics,
           Thrive Centers cage rotors                              63

12         Observed relationships between SRT and removal of
           total and volatile solids                               68

13         Observed relationships between SRT and removal of
           organic nitrogen and COD                                68

14         Nitrogen transformations during the start-up period,
           Ditch II                                                74

15         Reoccurrrence of nitrite accumulation in Ditch II        76

16         Dissolved oxygen concentrations in Ditch I at the
           oxygen transfer capacity of 351 gms 02/1000 bird-hours  77

17         Mixed liquor concentrations of total and free ammonia
           plus pH at the oxygen transfer capacity of 351 gms 0?/
           1000 bird-hours                                         79

                                  vi

-------
                      LIST OF FIGURES continued
No.                                                              Page

18        Mixed liquor concentrations of total  and free
          ammonia plus pH at the oxygen transfer capacity
          of 520 gms 02/1000 bird-hours                            82

19        Dissolved oxygen concentrations in Ditch I at the
          oxygen transfer capacity of 520 gms 0?/1000 bird-
          hours                                                    83

20        Dissolved oxygen concentrations in Ditch II at the
          oxygen transfer capacity of 815 gms 0?/1000 bird-
          hours                                                    84

21        Dissolved oxygen concentrations in Ditch II at the
          oxygen transfer capacity of 790 gms Op/1000 bird-
          hours                                                    84

22        Comparison of mixed liquor and settling tank
          overflow total solids concentrations at MLTS
          concentration below 12,000 mg/£                          87

23        Comparison of mixed liquor and settling tank
          overflow total solids concentrations at MLTS
          concentration above 18,000 mg/a                          87

24        Typical results from a batch settling test,
          aerated poultry wastes                                   88

25        Zone settling velocity versus total solids con-
          centration in aerated poultry wastes                     89

26        Sludge volume index versus total"solids concen-
          tration in aerated poultry wastes                        91

27        Vertical section through a basic single deck, 18
          inch Sweco Vibrating Screen Separator                    93

28        Illustration of average material travel on the
          screen                                                   93

29        Assembly diagram of a Thrive Centers cage rotor          97

30        Sediment profile in Oxidation Ditch II, 1973-74         100

31   •     Sediment profile in Oxidation Ditch I, 1973-74          100
                                  Vll

-------
                     LIST OF FIGURES continued

No.                                                             Page
32        Sediment profile in Oxidation  Ditch  I,  1974-75          102
33        Sediment profile in Oxidation  Ditch  II,  1974-75         102
34        Cross section of a Hart Cup                            105
35        Observed relationship  between  SRT and removal of
          total solids in aerated poultry  wastes                  115
36        Observed relationship  between  SRT and removal of
          volatile solids in aerated poultry wastes               115
37        Observed relationship  between  SRT and removal of
          COD in aerated poultry wastes                           116
38        Observed relationship  between  SRT and removal of
          organic nitrogen in aerated poultry  wastes              116
                                 via

-------
                            LIST OF TABLES

TABLE                           TITLE                            PAGE
  1       Egg Production Flock Number and Size Changes,  U.S.         4
  2       Observed Total and Volatile Solids Destruction,
          Percent, as Related to Poultry Waste Stabilization
          Time                                                     10
  3       TKN Concentration, Percentage of Total  Solids  in
          Animal Wastes                                            11
  4       Nitrogen Losses from Aerated Poultry Wastes
          Attributed to Denitrification                            14
  5       Assumed Fresh Poultry Manure Characteristics             36
  6       Kinetic Coefficients and e m Used for Project  Oxida-
          tion Ditch Design         c                              39
  7       Expected Treatment Efficiencies of Aerobic Poultry
          Wastes Stabilization at a 20 Day SRT                     39
  8       Design Estimates of Oxygen Requirements                  40
  9       Design Values for Sludge Storage Time                    42
 10       Oxygenation Capacity for the Thrive Center Cage  Rotor    45
 11       An Outline of the Manorcrest Demonstration Activities    56
 12       Summary of Initial Operating Conditions, September,
          1973                                                     57
 13       Changes in Operating Conditions                          58
 14       Results of Oxygen Transfer Measurements - Ditch  I        60
 15       Results of Velocity Measurements - Ditch I               61
 16       Results of Oxygen Transfer Measurements - Ditch  II        62
 17       Results of Velocity Measurements - Ditch II              62
 18       Raw Manure Characteristics, Manorcrest Farms             65
 19       Comparison of COD Removed with Oxygen Supply              70
                                   ix

-------
                      LIST OF TABLES continued
TABLE                          TITLE                            PAGE
 20      Dissolved Oxygen Concentrations                           71
 21      Observed Removal of Soluble COD                           72
 22      Relationships Between Oxygen Transferred and
         Removal  Efficiencies of Organic  and  Total  Nitrogen        78
 23      Change in Mass of Ammonia  Nitrogen in Ditch  I  at
         351  gms  02 Transferred/1000 Bird-hours                   80
 24      Results  of Centrifuge Test                               90
 25      Relationship Between Lead  Angle  and  Performance
         200 Mesh Screen, 0.074 mm                                 94
 26      Results  of Single and Two  Stage  Screening  Trials         95
 27      Comparison of Initial Ditch Velocities at  Volumes
         of 68,877 t and 105,980 i.                                101
 28      Sediment Characteristics                                101
 29      Initial  and Annual  Capital  Costs, Manorcrest Project
         Aeration Systems Components                             108
 30      Total  and Annual Capital Costs for the Manorcrest
         Aeration System                                         109
 31      Energy Costs for Aeration  in Relation to the Level
         of Oxygen Transfer                                      110
 32      Operating Costs for Manorcrest Aeration Systems  per
         1000 Hens per Year                                      111
 33      Cost Summary of Aeration of Poultry  Wastes,  Manorcrest
         Farms                                                    1i2
 34      Comparison of the Physical  Details of Manorcrest
         Ditch  II  and an Oxidation  Ditch  Discussed  by
         Windt  et al.                                             128
 35      New  York State Egg  Production Costs                      132
                                 x

-------
                      LIST OF TABLES continued
TABLE                          TITLE                            PAGE

 36      Comparison of Capital  Costs per 1000 Birds,
         Manorcrest Farms and Houghton's Poultry Farm            134

 37      Effect of Power Costs  for Aerobic Stabilization on
         Egg Production Costs                                    136

 38      Effect of Total Costs  for Aerobic Stabilization on
         Egg Production Costs                                    136
                                  XI

-------
                           ACKNOWLEDGEMENTS

This research was supported by the Environmental Protection Agency under
project number S800863; Manorcrest Farms, Camillus, New York; and the
College of Agriculture and Life Sciences, Cornell  University.  The
guidance of Mr. Lee Mulkey, Environmental Protection Agency, Athens,
Georgia who served as the project officer is gratefully acknowledged.

Most sincerely appreciated are:

- The contributions of Mr. and Mrs. Earl  Hudson and the personnel of
  Manorcrest Farms,
- The technical assistance of Lorraine Marnell  and Charles Barton,
- The help of R.J. Krizek and J.F. Gerling in preparation of the figures,
- The patience and skill of Sue Giamichael in typing the report.
                                  xii

-------
                             SECTION I
                            CONCLUSIONS

1.  Properly designed aeration systems for poultry wastes will  provide
    excellent control of odors as well as removal of COD, total  and
    volatile solids, and nitrogen.
2.  The process can be utilized to meet individual waste management
    objectives such as odor control, odor control and nitrogen  removal
    via nitrification-denitrification, or odor control and possibly
    nitrogen conservation.
3.  Odor control can be achieved by satisfying the exerted carbonaceous
    oxygen demand.  The quantity of oxygen transferred to achieve odor
    control was 351 gms 0? per 1000 bird-hours.
4.  Removal of total and volatile solids and COD, increase with  solids
    retention time  (SRT).
5.  Removal of soluble COD exceeded 85 percent at SRT's of 10 days
    or longer.
6.  The potential for nitrogen removal is controlled by the ammonifi-
    cation of organic nitrogen which is also a function of SRT.
7.  Losses of nitrogen will occur via ammonia desorption or nitrifi-
    cation-denitrification in oxidation ditches.  The removal mechanism
    is dependent on the level of oxygen supply.  Observed losses ranged
    from 48.8 to 63.3 percent of nitrogen loading.
8.  Complete oxidation of ammonia with simultaneous denitrification
    occurred at the oxygen transfer level of 520 gms Op per 1000 bird-
    hours.  This slightly exceeded the calculated, exerted carbonaceous
    and nitrogenous oxygen demand.

-------
 9.   The potential  for nitrogen conservation  by  storage  in  the tİv-:N
     form is  unclear but oxygen requirements  are high.   Favorable  con-
     ditions  for denitrification make  the  practicality of this approach
     questionable.

10.   Control  of mixed liquor total  solids  concentrations is desirable
     to optimize system performance.   No conclusions  could  be drawn as
     to the best method of liquid-solid separation  with  aerated  poultry
     wastes.   Both gravitational settling  and centrifugation appear to
     have potential, but additional  study  is  necessary.

11.   Sediment accumulations in oxidation ditches due  to  improper physical
     design can result in process failure.   Improved  hydraulic design
     can help overcome this problem.

12.   The use  of aeration systems for poultry  wastes will  increase  egg
     production costs.  Energy cost for odor  control  was $0.0033 per
     dozen eggs which represents a  0.8 percent increase  in  1973  New York
     egg production costs.   Total cost was  $0.0167  per dozen eggs  or  3.8
     percent  increase in production  costs.  Although  these  costs appear
     reasonable, further opportunities for  reduction  exist.

-------
                              SECTION II
                     PROJECT NEED AND OBJECTIVES
PROJECT NEED
Significant changes in the efficiency of commercial egg production have
occurred in the past 20 years.  The result is an increasingly intensive
industry with fewer commercial egg farms and higher numbers of laying
hens per farm.  Data for the years 1964 and 1969 (Table 1) show this
trend.  Today (1975), 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 the
largest farms containing 300,000 to 500,000 hens.  The gains in efficiency
in egg production have been accompanied by serious problems in the area
of waste management.  The satisfactory disposal of poultry wastes is
necessary for both environmental protection and successful egg production.

Perhaps the most important factor in the development of commercial egg
production as it exists today was the change from the floor to the cage
management 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.

The floor or litter system had two disadvantages which resulted in the
conversion to the cage management system.  One, the cage system allowed
an increase in bird density which lowered capital 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.  Dirty eggs and disease problems resulted.  Conversion to the

-------
          Table 1.  EGG PRODUCTION FLOCK NUMBER
                    AND SIZE CHANGES,  U.S.  (1)



1964

Chickens on hand, 4 months old and over

Under 100
100 - 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

-------
cage system reduced floor area per bird to about 0.04 square meters
(0.45 square feet).

The second disadvantage of the floor system was its high labor require-
ment.  The cage system permitted the mechanization of feeding, egg
collection, and manure handling, thus reducing manual labor requirements.
With the floor system, one man could care for approximately 5,000 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 a characteristic of the floor system no longer occurred.  The raw
waste which has a moisture content of about 75 percent wet basis, was
collected in pits beneath the cages.  Due to the semi-solid nature of
the waste, liquid manure handling techniques were possible.  Additional
water was normally added either 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 liquid manure storage and handling techniques created an
ideal environment for uncontrolled, anaerobic microbial activity.  Such
activity results in objectionable odors which are exhausted through ven-
tilation fans and are dispersed when the wastes are disposed of on the
land.  The odors consist of malodorous mercaptans, amines, volatile
acids, and sulfides.  Odor problems related to poultry farms have
resulted in legal and administrative actions by a number of state environ-
mental agencies.

The trend towards intensification in the egg industry has been accom-
panied by specialization.  Many farms, especially the larger operations,
purchase some or all the feed required.  Therefore, land for the production

-------
of feed is not necessarily a part of these farms.  In many instances
purchase of feed may present economic advantages.  The result can be
heavy waste loadings on small areas which intensifies the potential  for
water pollution.  Of particular concern is the loss of nitrogen to both
surface and groundwaters.  Numerous studies (2,3,4) have shown that
nitrogen is the limiting parameter in the disposal  of animal  wastes to
the land.

Aerobic biological treatment processes have the potential to  eliminate
odor problems associated with poultry wastes (5,6), provide an innocuous
method for nitrogen removal when required, and provide waste  stabiliza-
tion through the removal of readily biodegradable organic compounds.
Experiences with oxidation ditches have indicated they are an aerobic
treatment process that can accomplish these benefits and be a feasible
treatment unit for poultry wastes.

OBJECTIVES
Although laboratory and pilot plant investigations  have provided a great
deal of information about the application of aerobic  biological processes
to poultry wastes, the feasibility under full  scale commercial conditions
has been unclear.   The objective of this project was to establish an
aerobic biological treatment system on a commercial poultry farm in
order to:

     1)   Demonstrate and evaluate the potential of  aerobic treatment
         to reduce the air and water pollution potential of poultry
        wastes  under commercial  conditions.
     2)   Identify  problem areas in the design and operation of these
        systems and  evaluate possible solutions to these problems.
     3)  Evaluate  the economic impact of aerobic treatment of poultry
        wastes.
    4)  Develop operating procedures which will serve as guidelines
        for commercial  applications.

-------
                             SECTION III
                      THEORETICAL CONSIDERATIONS
INTRODUCTION
The use of aerobic biological processes for the stabilization of animal
wastes such as poultry manure has been preceded by their application to
domestic and industrial wastes.  However, the process fundamentals are
independent of the type of waste undergoing treatment.  Therefore, basic
information derived from domestic and industrial waste treatment studies
can be applied in the biological treatment of animal wastes.  However,
for the rational use of fundamental concepts developed from domestic
and industrial wastewater treatment, differences in treatment objectives
and waste characteristics should be recognized.

Normally, domestic and industrial wastewaters are discharged to surface
waters.  This requires high levels of removal of both oxygen demanding
and nutrient compounds.  In contrast, the effluent guidelines for the
feedlot industry (7) state that animal wastes should not be discharged
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 changes the treatment objectives.  In light of the waste
stabilization capacity of soils, emphasis in animal waste treatment is
on the removal of the oxygen demanding and nutrient fractions which are
susceptible to movement to both surface and groundwaters.  Achievement
of these objectives will provide the necessary control of odors.

The characteristics of animal wastes subjected to biological treatment
differ significantly from conventional municipal and industrial wastes.
Animal wastes have both greater oxygen demand and higher solids concen-
trations.  Removal  of settleable solids prior to treatment is not necessary,

-------
 High solids  loadings  are  a  characteristic of aerobic treatment units for
 animal  wastes.   Since these units  are  normally operated at relatively
 long solids  retention times  (SRT's), the process is comparable to combined
 activated sludge and  aerobic digestion.

 With the recognition  of these differences, many of the principles which
 have been developed in studies of  conventional biological waste treat-
 ment can be  successfully  applied to animal waste treatment.  This will
 provide a more  rational approach to the design and operation of animal
 waste treatment systems and  result in more reliable and efficient operation.

 POULTRY MANURE  - CHARACTERISTICS AND TRANSFORMATIONS
 Raw poultry  excreta is a  complex substrate containing soluble and parti-
 culate  inorganics and organics.  The organic fraction contains carbona-
 ceous and nitrogenous components which vary in their rate of biodegrada-
 bility.   The non-biodegradable inorganic or fixed solids constitute about
 20  to 28 percent by weight  of poultry manure total solids (8,9,10).
 Phosphorus,  calcium,  and  chlorides are the major components of fixed
 solids  (10).  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.  Although  the percentage of fixed solids will vary
 with feeding  practices, 25  percent appears to be a reasonable average
 estimate.

 Due to the complex nature of the organic fraction, substrate utilization
 rates for  the various  components vary significantly.  In a batch study
 involving  the non-settleable components of a poultry manure suspension,
 three distinct COD removal rates over a 20 day period were observed
 (Figure  1).  The  most  rapid  removal of COD occurred during the first  10
days of  treatment.  Additional removal results from utilization of the
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 1).

-------
    1.0
Q 0.6
O
o


O 0.4
                           BATCH UNIT
                           40 g/l SETTLED
                           POULTRY MANURE SUSPENSION
  O , c
x  15
CO

§  'o
O
CO
o 0.8
LJ
O
   0.6
CO
ID
CO
1
)
1
4
1 1
8
1 1
12
I 1
16
|
20
                    AERATION TIME, days
Figure 1.  Removal characteristics of total COD and suspended solids -
         semi-logarithmic plot 01)

-------
                       Table  2.   OBSERVED  TOTAL  AND  VOLATILE  SOLIDS DESTRUCTION
                                 PERCENT,  AS  RELATED TO  POULTRY WASTE
                                 STABILIZATION TIME
                                                 Average  Solids  Retention Time
   Parameter          12  days  (12)*       36 days  (12)       4.5 mo  (6)      6.5 mo  (9)      7.5 mo  (9)
Total solids
Volatile solids
COD
27
35
26
47
64
51
53
63
63
43
56
60
42
54
"
*Numbers in parentheses  indicate  data  source

-------
 The removal of total and volatile solids and COD with time observed by
 various investigators is presented in Table 2.  These data were collected
 from both pilot and full scale oxidation ditches.  The 12 and 36 day
 results were collected from a continuous flow system, whereas the other
 data were obtained from continuously loaded batch systems.  The compar-
 ison indicates that little additional removal of solids or COD occurs
 when time of treatment is extended beyond 36 days.  An important factor
 is that approximately 50 percent of the total solids added to the system
 remains as residual solids following treatment.  This results in a con-
 tinuous increase in total solids concentration in a continuously loaded
 batch system.

 An important characteristic of poultry manure is the concentration of
 nitrogen.  In comparison to the wastes of other major agricultural  species
 of domestic animals, poultry excreta contains the highest concentration
 of nitrogen (Table 3).
         Table 3.  TKN CONCENTRATION, PERCENTAGE OF TOTAL SOLIDS
                   IN ANIMAL WASTES
                       Beef          Dairy         Swine        Poultry
 TKN, % of T.S.      1.9 (13)*      4.9 (14)      3.4 (15)       8.4 (16)
*Numbers in parentheses indicate data source

 The nitrogen in poultry manure is in the form of proteins and uric acid.
 About 65 to 75 percent of the TKN in fresh poultry wastes is in the form
 of uric acid (17).  This nitrogen undergoes transformation during waste
 storage and stabilization.  Both proteins and uric acid can be converted
 to ammonia under aerobic and anaerobic conditions.  Uric acid results  in
                                     11

-------
 urea which  in  turn  is converted to ammonia.  These reactions can be com-
 bined  under the  term ammonification and expressed as:
                     Ammonification                         .
   Organic  Nitrogen	ğ• NH3 + H2<3 _        NH4 + OH"   (1)

 Ammonification results in an increase in pH due to ionization of NH^OH.
 If ammonium concentrations and pH are sufficiently high, ammonia volatili-
 zation will  occur.

 Under  aerobic  conditions, ammonia nitrogen can be microbially oxidized
 to nitrite  and nitrate nitrogen.  The two groups of microorganisms
 primarily responsible for this transformation are Nitrosomonas and Mitro-
 bacter.  The oxidation of NH. to NO- is a two step process termed nitri-
 fication and can be expressed as follows:
                .           Nitrosomonas
             NH   +  3/2 0  	>• m~ + 2H  + H0             (2)
                                  Nitrobacter
                    NO~ + 1/2 o2	> NO"                   (3)

Nitrification studies have indicated that 50 to 60 percent of the initial
TKN in poultry wastes could readily be nitrified.  Therefore, 50 to 60
percent of the initial organic nitrogen was easily converted to ammonia,
since the fresh manure contains only trace amounts of ammonia.

Nitrifying organisms and hence nitrification can occur in natural waters
and soils as well as in waste treatment systems.  The process results in
the exertion of a nitrogenous oxygen demand (NOD) which is important in
both natural waters and waste treatment systems.  In poultry manure, the
NOD is significant being equal to approximately 25 percent of the chemical
oxygen demand of the waste.
                                                   ^
Under anaerobic conditions, nitrite and nitrate nitrogen can be reduced
to nitrogen gas (N2) or nitrogen oxides (N20 or NO) by denitrifying
                                   12

-------
microorganisms.  The combined processes of nitrification-denitrification
can result in significant nitrogen removal from aerated poultry wastes.
Some observed nitrogen losses from aerated poultry wastes attributed to
denitrification are presented in Table 4.

PROCESS DESIGN
General
The design criteria for aerobic treatment of animal wastes suggested by
Jones et al.  (21) has served as the standard basis of design for these
systems.  Both the Midwest Plan Service and the Canada Department of
Agriculture suggest this method of process design (22,23).  These design
criteria are  empirical based upon studies involving swine and dairy
cattle wastes.  System volume is determined using the organic loading
                                                            o
rate concept.  The recommended loading rate is 0.5 kg BODc/m /day (0.03
           3
Ibs BODg/ft /day).  The suggested parameter for oxygen requirement is
twice the daily BODg loading assuming that in the stabilization unit, the
aeration system will transfer 80 percent of the amount it will transfer
in tap water.

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.

This organic  loading rate concept represents an early approach to slurry
type biological treatment system design.  A more fundamental approach was
developed from the observation that effluent quality was related to the ratio
of substrate  loading (F) per unit time and the mass of microorganisms  (M).
                                     13

-------
        Table 4.  NITROGEN LOSSES FROM AREATED POULTRY WASTES
                  ATTRIBUTED TO DENITRIFICATION

System Type
Oxidation Ditch
Oxidation Ditch
Diffused Aeration Basin
Oxidation Ditch
Oxidation Ditch
Dissolved Nitrogen
Oxygen, mg/Ji Loss, %
2-7 36
2-6 66
0-2 50-60
0-6 70-80
* 30-90
Reference
6
9
18
19
20
*Intermittent to continuous aerator operation
                                   14

-------
As the substrate loading increased, effluent quality deteriorated.  Based
upon these observations, the food to microorganism  (F/M) ratio was
established as a design parameter for biological treatment processes (24).
Owens et al. (25) have investigated the effects of different F/M ratios
on effluent quality in the aerobic treatment of swine wastes.  Their
observations of decreasing effluent quality at increasing F/M ratios con-
curred 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.
Traditionally, volatile suspended solids concentrations (VSS) have been
used to estimate active mass.  Due to high concentrations of VSS present
in raw poultry manure, this method of estimation has little significance
in poultry wastewaters.

Other design approaches have been developed based upon microbial kinetics
using first order substrate utilization kinetics.  These approaches can
be applicable to poultry wastes (11).

Another kinetic approach has used a Monod (26) type equation as the basis
of a treatment model.  This approach relates microbial growth to a limit-
ing substrate concentration.  Substrate limited growth appears a more
precise description of conditions in biological waste treatment systems
than the first order substrate utilization approach.  Practical appli-
cation of this approach (27) utilizes the biological solids retention
time, 9 , as the unifying design parameter in that all system variables
can be related to it.  Mathematically, e  can be represented as
                                                                     (4)
                                   (AX_)
                                   k    '
where     XT = total active microbial mass in
               treatment system, mass.
                                    15

-------
           (AX/At)T = total quality of active microbial
                     mass leaving the system in a unit
                     of time, mass per time.
 As  e   increases,  the effluent concentration of the growth limiting sub-
 strate will  decrease.  The microorganism concentration is a function of
 the available  substrate concentration and 6 .  Excess microorganism pro-
                                           N*
 duction  is also related to 9 .  As e  increases, the excess microorganism
 production will decrease due to endogenous respiration.

 This  latter  approach is not unlike the F/M approach.  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
           C                                                          \f
 design approaches have been compared in a treatability study of an oil
 refinery wastewater  (28) and found to produce similar designs.

 The design equations for most approaches have been developed based on
 studies  involving liquid wastes.  Although the equations are fundamental
 to  all biological systems, detailed application to a waste such as poultry
 excreta  is difficult.  One factor is the high solids concentration of
 the poultry  waste.  Whereas the influent solids concentrations of municipal
 and certain  industrial wastes are small in comparison to concentrations
 in  the treatment  system, the reverse can be true with poultry and other
 animal wastes.  This complicates determination of kinetic coefficients
 which  depend on measurement of volatile suspended solids to estimate
 cell mass.
A second problem is introduced due to the complex nature of the waste.
Due to the composition of these wastes, the single substrate hypothesis
is not directly applicable.  In waste treatment, it is normally assumed
that the limitation of total biodegradable material controls microorganism
population.  Due to the limitations of the BOD determination, COD  is
commonly used to estimate biodegradable compounds.  However, the COD  test
measures both biodegradable and non-degradable compounds which are subject
to chemical oxidation.  Therefore, it is necessary to estimate the
                                   16

-------
biodegradable portion of COD.  This approach was used (29) to model the
aerobic treatment of swine wastes.  However, the biodegradable fraction
is a function of time of treatment due to the different substrate utili-
zation rates for different fractions of the organic matter.  Therefore,
estimation of the biodegradable fraction is a function of the time of
treatment and vice versa.

Although there are inherent difficulties in the detailed application of
substrate limited approach (27) to the aerobic treatment of poultry and
other animal wastes, it provides a rational basis for relating treatment
efficiency to 6 .  In this context, treatment efficiency expressed as
               c*
removal of COD, total and volatile solids, and/or degradation of organic
nitrogen can be related to and controlled by manipulation of e .  Changes
in both COD and organic nitrogen removal have been related to e  in
                                                               \Ğ
aerobically treated  poultry wastes  (16).

Determination of e  as defined in Equation (4) requires measurement of
                  \f
active biomass.  However, assuming complete mixing resulting in the
uniform distribution 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
/5\
*  '
                        wt of solids in the system _
                    wt of solids leaving the system/time
6  is a function of the active biomass in a system while SRT can be
 c
determined by measuring other forms of solids such as volatile, suspended,
total suspended, or total solids.  If the system is completely mixed,
SRT is a reasonable estimate of ec and is the key factor in the utili-
zation of this approach.  The unifying parameter, SRT, can be estimated
by utilizing an easily determined parameter, solids concentration.

Both biochemical oxygen demand (BOD) and chemical oxygen demand (COD)
tests are methods which provide an indirect measure of available substrate
in terms of the oxygen equivalent of organic matter.  An advantage of
                                    17

-------
 the BOD determination  is  that  unlike the COD test it includes only
 organic matter susceptible  to  biological degradation.  However, the BOD
 test is dependent on both the  time period and initial seed.  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 across a treatment
 system is being measured, COD  appears to have an advantage.  By assuming
 that a change in COD is due completely to biodegradation, concern with
 the non-biodegradable  fraction of COD is eliminated.  Theoretically,
 the change in COD can  be  considered equal to the change in BOD.

 Another advantage of the  COD test is the relatively short analysis time
 required in  comparison to BOD  determinations.  Results of COD analyses
 are available in less  than  three hours, whereas the BOD test requires
 a  minimum of five days.   For these reasons, further discussion will
 focus  on COD rather than  BOD.

 CHEMICAL OXYGEN  DEMAND
 The  requirement  for removal of COD in the aerobic treatment of poultry
 manure  is  a  function of the place of ultimate disposal, the land or
 surface  waters.   As noted earlier, the land is the most logical site
 for  ultimate  disposal   of  these wastes.  In this context, the significance
of COD removal  is changed.  The land has the ability to stabilize  the
organic  carbon in poultry wastes at application rates of dry solids up
                                     18

-------
to 101 metric tons/ha/yr (45 tons/ac/yr) (2).  Loading rates of this
magnitude were shown to be excessive in terms of nitrogen.  Therefore,
at acceptable application rates of nitrogen, high levels of COD removal
do not appear necessary.

The importance of COD removal in the aerobic treatment of poultry wastes
lies in two areas:  odor control and removal of soluble organics which
are subject to transport in surface runoff.  To provide odor control,
the exerted COD must be satisfied aerobically.  Otherwise, the biologi-
cally available COD will be utilized as substrate by anaerobic organisms
with the production of malodors.  The soluble COD fraction is the most
readily available substrate (11) in poultry wastes.  Therefore, the
oxygen required for odor control will also reduce the soluble organics
in the effluent.

The COD of fresh poultry excreta includes both biodegradable and non-
biodegradable compounds.  In addition, the test does not distinguish
between rapidly and slowly biodegradable compounds.  However, oxygen
requirements can be related to COD removal, i.e., exerted oxygen demand.

The following general equation describes the rate of oxygen utilization
for the oxidation of carbonaceous matter:
          H!= rate of oxy9en utilization
          41- = rate of substrate utilization
          dt
          Y  = coefficient to convert substrate
               units to oxygen units
          b  = microbial decay coefficient
          c  = coefficient to convert cell mass
               to oxygen units
          X  = microbial cell concentration
                                    19

-------
 Since  both  terms, substrate utilization and endogenous respiration, are
 manifested  as  COD removed, Equation 6 can be rewritten as:
                             do _ dCCOD]                             m
                             dt "   dt                             '  Uj
 COD removal  in aerated poultry wastes is a function of time of treatment,
 i.e.,  SRT (11,16).  The required degree of stabilization, hence COD
 removal,  can vary for individual situations.  This variation is related
 to possible storage of effluent and possible odor problems during final
 disposal.   Another factor  is the potential for surface runoff.  By the
 control of  SRT,  COD removal can be matched with overall waste management
 objectives  and is a rational approach to estimate carbonaceous oxygen
 requirements.

 NITROGEN
 The objective  of nitrogen  management in aeration of poultry wastes is
 a  function  of  the overall  farm operation.  As previously discussed, a
 poultry farm may or may not engage in crop production.  Where crop
 production  is  involved, nitrogen conservation, to the extent that the
 nitrogen  can be  recycled through a crop, is a logical objective.  Con-
 versely,  nitrogen removal  can be necessary when productive land for
 ultimate  disposal is limited.

 The best approach for nitrogen conservation in aeration systems will
 depend on the  quantity of  available land and on the nitrogen management
 objectives of  the poultry  operation.  A number of possible approaches
 exist.  One  involves nitrification which was described earlier.

Although several groups of microorganisms are capable of nitrification,
two groups of autotrophs,  Ni trospmonas and Nitrobacter. are of primary
importance in wastewaters.  The first step of the process releases
hydrogen ions with a resultant depression in pH.

Nitrification is an aerobic process requiring oxygen above that supplied
to satisfy exerted carbonaceous demand.  Therefore, Equation  7, which

                                    20

-------
described the relationship between rate of oxygen utilization and COD
removal, must be modified as follows:
                  -+3                                       ,,.
               dt   .  dt   + 3.43— g^-+ 1.14 - g^                (8)

where     d[NH*]     d[N02]
          - dt~ and — dt —  are resPectively, the rates of oxidation
          of ammonia to nitrite and nitrite to nitrate.

Thus, one approach  to achieve high nitrogen conservation is to obtain a
high level of nitrification.  This can be accomplished by providing
sufficient oxygen for the aerobic system, adequate mixing, and a sufficient
SRT.  However, even with complete nitrification, total nitrogen conser-
vation may not result since denitrification can occur.  A number of
facultative microorganisms will utilize nitrites and nitrates as terminal
electron acceptors  in place of molecular oxygen under anaerobic conditions.
Although the actual reactions are complex, they can be summarized as
follows:
           2 NO" +  10 H* - > N2 t + 4 H20 + 2 OH"    (9)

           2 N02 +  6 H+  - : - ğ N2 + + 2 H20 + 2 OH"   ^10^

The production of nitrogen oxides, N20 and/or NO, is possible.  Analysis
of gases from denitrification of aerated poultry wastewater indicated
that N2 is the major end product (30).

Although nitrifying organisms are autotrophic, denitrifiers are hetero-
trophic and require a source of organic carbon.  In well stabilized
effluents, addition of a source of organic carbon such as methanol is
normally required.  However, there is ample oxidizable organic carbon
in poultry wastes and it does not appear that organic carbon will be
the limiting substrate for denitrification in poultry wastewaters.

Another alternative to accomplish nitrogen conservation is to prevent
nitrification and thus avoid subsequent denitrification and nitrogen loss.
                                     21

-------
 A  number  of methods exist.  One would be to exclude nitrifying organisms
 from  the  aeration  system.  Although these organisms are not present in
 fresh poultry wastes  (30), they are widely distributed in the soil and
 can be easily introduced into aerobic treatment systems.  Therefore,
 such  exclusion would  be impractical under commercial conditions.

 A  second  method would be to reduce the system e m  for nitrifying
                                               V*
 organisms.  This is theoretically possible because both Nitrosomonas
 ancl Nitrobacter have  slow growth rates in comparison to heterotrophic
 organisms associated  with waste stabilization.  A e  of less than three
                                                   c
 days  at 20°C would be required (31).  At this and shorter SRT values,
 waste stabilization would be minimal and the effectiveness of aerobic
 stabilization diminished.

 A  third and possibly  the most practical approach is to limit oxygen
 availability.  Nitrifying bacteria cannot compete with heterotrophic
 organisms for oxygen.  Therefore, limiting oxygen input to that required
 to satisfy the exerted carbonaceous oxygen demand will prevent nitrifi-
 cation.   Nitrogen  losses can still occur via ammonia stripping.  Predic-
 tion  of these losses  is possible although difficult due to the variables
 involved  such as ammonia concentration, pH, temperature, and degree of
 turbulence.

 Biological nitrification-denitrification is a feasible approach for
 nitrogen  control with poultry wastes (4,11,30).  This approach is
 attractive due to  its compatibility with aerobic treatment for odor
 control.  The only difference is that conditions to control nitrification
 and denitrification also are provided.

OXYGEN TRANSFER
 In an aerobic system, the oxygen transferred should be equal or greater
 than the biological oxygen requirements of the system.  The oxygenation
capacity of aeration equipment is normally determined in tap water at a
                                   22

-------
zero dissolved oxygen concentration.  However, equipment oxygenation
capacity can vary under process conditions.

Oxygenation under process conditions can be described as:
                     N = aKLa(0Cs-CL) (W)  (10~6)                   (11)

where     N   = oxygenation capacity, pound-time'1
          KLa = overall gas transfer coefficient, time
          a   = the ratio of KLa in wastewater to KLa in tap water
          Cs  = oxygen saturation concentration, mass/volume
          3   = the ratio of C  in wastewater to C_ in tap water
                              o                   S
          C.   = the equilibrium dissolved oxygen concentration,
                mass/volume
          W   = weight of liquid under aeration, pounds
The values of K,a and W are functions of the aeration unit and system
volume, and are constant for a given operating condition.  C  is an
independent variable related to liquid temperature and atmospheric
pressure.  Both a and B are dependent variables.  Although a is a
function of many factors, it appears that it is primarily related to
mixed liquor characteristics as is e (32).  C.  is a function of the
relationship between the quantity of oxygen supply and demand.  The
quantity of oxygen transferred is directly related to a.  Thus factors
that affect a directly affect the oxygen transferred under process
conditions.
Constituents of the mixed liquor under aeration can affect the quantity
of oxygen that is transferred.  Small quantities of surface active
agents can cause significant reductions in a values (33-35).  Downing (34)
found that suspended solids in the range of 1,000 to 6,000 mg/£ have had
little effect on oxygen transfer.  However, a was reported reduced to
0.2 in a sludge with a total solids concentration of 10,000 mg/£ (36).

Alpha values in aerated poultry wastes have been shown to be related to
mixed liquor total solids concentrations (6,37).  The results indicated
                                   23

-------
 that  a  has  the  value of  1.0 at mixed liquor total solids concentrations
 less  than 20,000 mg/£.   As total solids concentrations increase beyond
 that  point,  a values decrease to 0.4 at 55,000 mg/£.  This relationship
 between a and mixed liquor total solids concentration is presented in
 Figure  2.

 The oxygenation capacity is also a function of B (Equation 11).  An
 empirical relationship describing the effect of salinity on C  has
 been  developed  (38) and  may be used with reasonable accuracy for deter-
 mination of 6 in wastewater (39).  Beta values in the range of 0.9 to
 1.0 have been reported in studies involving domestic wastewaters (40-42).
 In aerated  poultry manure slurries, e appeared independent of total
 solids  concentrations  (42).  Beta values approached unity for total
 solids  concentrations up to 30,000 mg/£.

 The value of C,  is important in that as N increases above that necessary
 to provide  a minimum dissolved oxygen concentration, C,  will increase.
 The result  will be the decrease of the oxygen deficit, C -c, .  This in
 turn  will reduce the oxygen transfer efficiency of the aerator and
 increase operating costs.  In an aeration system, C,  need be no more
 than  that necessary for  odor control, generally no more than 0.5 to
 1.0 mg/£, or for nitrification, generally about 2.0 mg/a.

 The combined effects of  a expressed as total solids concentration and
 C. on required tap wateraeration capacity for poultry wastewater is
 shown in Figure 3.  The  consequence of increasing oxygenation capacity
 is translated into higher capital and operating costs.
                                                                 f
 The relationships of SRT to degree of waste stabilization, and mixed
 liquor total solids concentration to oxygen transfer described previously,
form a rational  basis for the design and operation of aeration systems
for poultry wastes.  These concepts were employed in the design of the
Manorcrest oxidation ditches and will be used in discussing and inter-
preting the results of this study.
                                   24

-------
to
01
                  UJ
1.4
1.2
™^^fc^.
""•*•ğ*
tr
£ 1.0
o_j -8
	 .6
i .4
1
J 2
t
(
•^^MMVk
(••^••••••^
•
*^>\
" "" *i.Ss
- ^J
•
1 1 1
3 2349
                                         TOTAL  SOLIDS-PERCENT
                             Figure 2.  Relationship between a and mixed liquor total  solids
                                      concentration in  aerated poultry wastes (37)

-------
1C
2oo:
I-. .UJ
                 CL
             z<
^CD1"?
£i_0 I

£^5 ^
0^5 Q
co...u. 9E
Q^w 5
             CLQI- =
 6



 5



 4



 3



 2



 I



0
                                                                   DISSOLVED
                                                                  OXYGEN-mg/l

                                                                       3
                               RECOMMENDED
                               OPERATING
                               RANGE

                               Mil    I
                                           TEMPERATURE Ğ 20°C
                                         I
                                                I
I
                               .5 I 1.5 20  25   30   3.5     40      4.5

                                  TOTAL SOLIDS  CONCENTRATION   (%)



                             Figure 3.  Aeration requirements in relation to mixed
                                      liquor total solids and C,  (37)

-------
                              SECTION  IV
       INVESTIGATIVE FACILITIES, SYSTEM DESIGN AND CONSTRUCTION

INVESTIGATIVE FACILITIES
This study was conducted at Manorcrest Farms No. 2 which is located in
Camillus, New York, less than 10 miles west of the city of Syracuse.
This area (1975)  is located in the outer fringe of the suburban Syracuse
area.  Details of the area are presented in Figure 4.

Manorcrest Farms  are owned and operated as a family partnership.  The
farming activities consist of dairy and poultry enterprises accompanied
by crop production to provide animal feed.  The main farm is the site of
the dairy operation.  Farm No. 2 is the location of two-thirds of the
poultry enterprise with cropping activities occurring on both farms.

The poultry operation is managed by Mr. Earl Hudson, one of the partners
in Manorcrest Farms.  He also served as grant director of this project.
This enterprise is an integrated  operation.  Home grown grains are used
in the manufacture of the poultry feed.  The eggs produced are processed
and packaged by Manorcrest Farms.  The major portion of the egg production
is sold at the wholesale level to retail food stores and institutions.
The remainder is  sold  at a retail outlet on the farm.

Building No. 1 (Figure 4) was the site of the demonstration activities.
The building is a single story poultry house with a capacity of 8,000
birds contained in four rows of stair-step cages.  Figures 5 and 6 are
a plan and cross-section of this building.  Prior to the installation of
the aeration systems, manure accumulated in 73 cm (29 in) deep pits and
was removed semi-annually.  Anaerobic  conditions prevailed in these col-
lection pits resulting in the production of malodors.  These odors were
discharged through ventilation fans and during manure spreading resulted
in neighbor complaints.  In addition,  a fly problem existed during  the
warm months of the year.
                                    27

-------
             RT.  5
                       TO CAMILLUS
         BUILDING
           NO. 2
            BUILDING
             NO. I
I	
            DISPOSAL AREA
            (CORNFIELDS)
                                            SITE PLAN
         RT5
3m[    CAMILLUS
            MANORCREST
            FARM NO. 2
           MAIN
           FARM
                                              SYRACUSE
                                           LOCATION
Figure 4.  Location and site plan of Manorcrest Farm No. 2
                      28

-------
     -5
     ft)
to
en
*



~o

EU



<



£
     CO
     c
     Q.

     3*
                                                           154'-0"
ħ
MANURE COLLECTION a STORAGE PITS ^^


)\
/ \
i 	


     cr
     n>
     -h
     O

     CD
      Q.

      -h

      O
      QJ
      rt-

-------
u
t]

<

* 0 n" >
* Jc. *
;..-4 . p.,- ..


4 Q°" 1.
* y £. '

44'
*
^ Q°" *
^ y t ^
n" 	



* QĞ" k
< 9
-------
The other building, Building No. 2, is a two-story, high-rise poultry
house with a capacity of 11,000 birds.  The birds are located on the
second floor.  The first floor serves as a manure collection and storage
area.  Ventilation air is circulated over the wastes to promote drying.
This building was not directly involved in the study except as a control
to compare conditions and manpower associated with other poultry production
and waste management situations.

Mr. Earl Hudson was responsible for the supervision of the construction
activities in converting the existing waste management facilities in
                                                 \
Building No. 1 to the aeration systems.  In keeping with the concept of
demonstration under commercial conditions, he was also responsible for
the operation of both oxidation ditches including maintenance and ultimate
disposal functions.  General operating procedures were provided by Cornell
University personnel.

Personnel from the Agricultural Waste Management Program, New York State
College of Agriculture and Life Sciences at Cornell University acted as
consultants to the project.  Their responsibilities included systems
design, provision of guidelines for operation, and evaluation of performance
including identification of problem areas.  Cornell personnel collected
and analyzed the data necessary for performance evaluation.

Also participating in the project were Professor Charles E. Ostrander,
Extension Specialist in Poultry Science, Cornell University and Mr. Antonio
Aja, Cooperative Extension Agent, Onondaga County, New York.  These indi-
viduals assisted in the transfer of the project results to the poultry
industry.

The oxidation ditches at Manorcrest were monitored for an 18 month period
in order to collect necessary data to evaluate their performance.  Cornell
personnel visited the demonstration site at least twice a week to observe
the systems, to make adjustments in operating procedures when necessary,
and to obtain samples.
                                     31

-------
 The Agricultural Waste Management Laboratory (AWML) at Cornell University
 served  as a  support facility for this investigation.  The laboratory was
 constructed  with funds from EPA Project 14040 DDG and contains a wet
 chemical laboratory, pilot plant process equipment, and animal housing
 facilities.   Figure 7 is a floor plan of the Laboratory and illustrates
 the area used for  sample analysis.  Cornell personnel associated with
 the project  were located at the AWML.  Analyses of Manorcrest samples as
 well  as supplemental studies were conducted in this facility.
                       &

 The Manorcrest demonstration site was visited by numerous individuals
 during  the course  of the study.  Visitors included representatives of
 the U.S. Environmental Protection Agency, the New York State Environmental
 Facilities Corporation, consulting engineers, and agriculturalists.  In-
 cluded  in this latter group were members of the Cooperative Extension
 County  Executive Committee of Onondaga County, New York, as well as
 several egg  producers.  The site was also inspected by foreign researchers
 and graduate students in the Agricultural Waste Management Program, Cornell
 University.   In addition, the Manorcrest study was the subject of an
 article in the June 1974 issue of the "American Agriculturalist" which
 is a  popular farm  magazine.  These activities were in keeping with the
 objective of the demonstration of aeration systems for poultry wastes.

 A portion of the results of this investigation was presented at the
 International  Symposium on Livestock Wastes - 1975 at the University of
 Illinois, Urbana - Champaign.  The paper "An Evaluation of Aeration Systems
 for Poultry  Hastes Under Commercial Conditions" was published in the
 proceedings  of that conference.  A second paper, "The Oxidation Ditch -
 Problems and  Reasons" discussing the problem areas identified in this
 study will  be  presented at the American Society of Agricultural Engineers
 1976 Summer Meeting at Lincoln, Nebraska.  The results of this study have
also been utilized by other members of the Cornell Agricultural Waste
Management Program in the preparation of scientific papers, reports,
and theses.
                                   32

-------
             LABORATORY
                PILOT   PLANT
              PROCESS  EQUIPMENT
POULTRY
                                       HOUSING  AND
WASTE
                                       MANAGEMENT
                                     WASTE  STORAGE
                           FLOOR PLAN

                   ANALYTICAL LABORATORY
Figure 7.   Floor plan and analytical laboratory in the Cornell
           Agricultural  Waste Management Laboratory
                                .;

-------
SYSTEM DESIGN
General
In  the design of the aeration systems for this study, it was recognized
that a comprehensive animal waste management system has three components.
           1)  stabilization
           2)  solids management
           3)  ultimate disposal
A number of aerated systems including an oxidation ditch and an aerated
lagoon were considered as possible alternatives.  An oxidation ditch
inside the poultry buildings appeared to be the most logical alternative
for the following reasons:
           1)  ease of incorporation in confinement housing
           2)  cold weather operational problems are eliminated
           3)  uniform loading directly from birds
           4)  equipment to move raw waste to the aerated unit is not
              required
In  addition, it was possible to easily convert the existing manure
collection pits to oxidation ditches.

The four existing collection pits, Figures 5 and 6, were converted into
two oxidation ditches as shown in Figure 8.  The only construction
required was the connection of each pair of ditches with semi-circular
channels at each end.  Each ditch served approximately four thousand
birds.

For design purposes, it was assumed that total solids production would be
40  gms/bird-days.  This value is comparable to the value of 37 gms/bird-day
reported elsewhere (16) and was conservative.  Maximum total solids
destruction was assumed to be 50 percent (Table 2).  Other waste charac-
teristics which were assumed are presented in Table 5 and are based upon
reported characteristics (16).
                                    34

-------
en
      SETTLING
    a STORAGE
      TANKS
                                                  If—T] PROPELLER
OVERFLOW
DITCH No.1
                   RECYCLE
                                 BRUSH  AERATOR
                                                                         DITCH No. 2
                                                    THRIVE  CENTERS
                                                    No. H-805 CAGE ROTOR
                         Figure 8.  Plan view of oxidation ditches and settling tanks

-------
         Table 5.   ASSUMED FRESH POULTRY MANURE  CHARACTERISTICS
               Parameter	Gms/bird-day
               Volatile solids                  29.7
               Fixed solids                     10.3
               TKN                              3.4
               COD                             31.1
               BODC                             8.1
 Stabilization
 Two different  modes  of oxidation ditch operation were considered:
           1) continuously  loaded, batch
           2) steady-state  with a constant SRT
 The continuously  loaded, batch method of operation has the advantage of
 combining  stabilization and storage.  This is probably the most common
 method  of  agricultural  oxidation ditch management.  With this approach
 the ditch  would be emptied periodically, refilled with tap water, and
 the system restarted.   Based upon a maximum mixed liquor total solids
                                                                *
 concentration  of  50,000 mg/£, maximum storage time for each ditch was
 calculated to  be  73  days.  The average SRT would be 26.5 days.  If the
 total solids production rate were 30 gm T.S./bird-day, which also has
 been reported  (10),  the storage time would be 97 days.

 The batch  method  of  operation has advantages in simplicity of operation
 and combination of storage with treatment.  However, there are several
 disadvantages.   The  primary liability is a low oxygenation efficiency at
 the high total  solids concentrations that ultimately result with a batch
system.  An a value  of  0.5 at a mixed liquor total solids concentration
of 50,000 mg/£ has been reported (37).  To maintain aerobic conditions,
the required oxygenation capacity would be approximately twice the oxygen
demand.   This would  result in increased capital and operating costs.
                                   36

-------
Other possible disadvantages to the batch mode of operation are:
          1)  potential of recurring  "start-up" problems such
              as foaming and an initial imbalance in the food
              to microorganism ratio.
          2)  high, short term water  requirements to refill the system.
          3)  additional energy requirements for mixing due to
              increasing viscosity at higher total solids concentrations.
It was possible that pumping and not  oxygenation capacity would be the
limiting criteria in sizing required aeration equipment for such a mode.

An alternative to the batch approach  is a steady-state process with control
of mixed liquor total solids concentrations via continual residual solids
removal.  This would allow maintenance of total solids concentrations of
less than 20,000 mg/£, thereby maximizing oxygenation efficiency.   With
this type of system, SRT would be a design and operating parameter.
This would allow flexibility in matching degree of stabilization with
overall waste management objectives.

Due to the potential advantages of maximizing oxygenation efficiency, the
Manorcrest oxidation ditches were designed to operate at low mixed liquor
total solids concentrations, and SRT was used as a basic design parameter.

The selection of the design SRT was based upon the objective of providing
conditions which would permit nitrification.  Since both Nitrosomonas and
Nitrobacter are known to have slower growth rates than the heterotrophic
organisms utilizing carbonaceous materials, calculation of the minimum
system SRT (e m) was based on nitrification.  Information about Building
             (_•
No. 1 indicated that the average minimum temperature should not be below
10°C.  Therefore, the value of 10°C was assumed as the minimum mixed
liquor temperature.

The kinetic coefficients for nitrification at 20°C (44) were used to
calculate e m.  A modified form of the van't Hoff-Arehenius relationship,
                                    37

-------
 Equation  12, was assumed adequate to correct the 20°C value of the maximum
 rate  of substrate  utilization per unit weight of microorganisms, K, to
 10°C.  The  corrected  K  in  turn was used to determine e m at 10°C.
                                                      \*
                                      (VT,)
                         KT  = KT  . 6  Z  ]                        (12)
                           '2     'l
 where    e =  1.106
          T =  temperature  °K
 The e value of 1.106  is that reported (44) for nitrification in the
 temperature range  of  5  - 20°C.   e m was calculated by using Equation 13 (27),
                             9cm =  (YK-b)"1                          (13)

 The  kinetic  coefficients and  0 m at 20°C and the calculated e m at 10°C
                                        m
 are  noted  in Table  6.  The calculated 6   values of 2.1 and 2.9 days for
                                       \f
 ammonia  and  nitrite oxidation at 20°C compare favorably with the two day
 8 m  for  nitrification of poultry wastes reported elsewhere (4).

 Based  upon these calculations, a design SRT of 20 days was chosen to
 provide  a safety factor of two for nitrification during winter operations.
 In order to  simplify the design and prediction of parameter removals, it
 was  assumed  that SRT would be constant throughout the year.  The expected
 performance  at this design SRT was estimated from relationships of parameter
 removal  and  SRT that occurred in other poultry waste stabilization studies
 (12).  The expected performance is presented in Table 7.

 The  anticipated solids destruction and resultant solids concentration
were used to  calculate the required volume for each ditch.  A volume of
 105,980  £ (28,000 gal) was calculated to have an  equilibrium total solids
concentration of 19,777 mg/a at a 20 day SRT.  This value  is slightly
below the 20,000 mg/£ which is the upper limit for best oxygenation
efficiency.  This volume resulted in a depth of 50.8 cm (20 in) in each
Manorcrest ditch with a freeboard of 20.8 cm (8 in).
                                     38

-------
Table 6.  KINETIC COEFFICIENTS AND ecm FOR BIOLOGICAL NITRIFICATION
          USED FOR PROJECT OXIDATION DITCH DESIGN
Process

NH4-N
Oxidation
N02-N
Oxidation
Y, mg/mg N

0.29
0.29
0.084
0.084
b, days"
0
0.05
0.05
0.05
0.05
K, mg N/mg-day

1.8
0.7
4.7
11.7
T°C

20
10
20
10
ecm, days

2.1
6.5
2.9
10.7
       Table 7.  EXPECTED TREATMENT EFFICIENCIES OF AEROBIC
                 POULTRY WASTES STABILIZATION AT A 20 DAY SRT
                Parameter                   % Removal

             Total Solids                       33
             Volatile Solids                    46
             COD                                36
             Organic Nitrogen                   62
                                 39

-------
                                                                3
 The  design  volume was  compared to the parameter of 0.5 kg BODr/m -day
 (0.03  Ibs BODj-ft -day)  suggested as adequate for oxidation ditch design  (21).
 A  BOD,-/T.S.  ratio of 0.20 for poultry manure was assumed  (Table 5).  The
                                 o
 design volume  of 105,989 £  (106 m ) had an expected volumetric loading
                     3
 rate of 0.3 kg BOD5/m  -day.  Thus adequate performance was expected.

 Oxygen requirements to satisfy carbonaceous and nitrogenous oxygen demand
 were determined utilizing Equation 8.  It was assumed that one unit mass
 of COD removed represented  one unit mass of carbonaceous oxygen demand
 that was satisfied.  Based  upon the assumed waste characteristics presented
 in Table 5  and the anticipated removals, Table 7, the daily COD removal
 for  each ditch was calculated to be 44.78 kg/day and therefore the oxygen
 requirement for carbonaceous oxygen demand was assumed to be 44.78 kg/day.
 The  anticipated nitrogenous oxygen demand was an additional 38.20 kg 0?/day.
 The  anticipated oxygen requirements for the two levels of treatment, odor
 control  and odor control plus nitrification, per 1000 bird-hrs, were:
          Table 8.  DESIGN  ESTIMATES OF OXYGEN REQUIREMENTS
              Degree of Treatment             Gms O^/IOOO
                                               bird-hr

                Odor control                    470
                Odor control &
                Nitrification                   860
The value of 860 gms 0^/1000 bird-hrs compared favorably with  the  oxygen
requirement of 940 gms Op/1000 bird-hrs determined from oxygen uptake
rate measurements reported by Baker et al.  (37), for an oxidation  ditch
treating poultry manure.  The design value  of 860 gms  0^/1000  bird-hrs
is conservative when compared to the 2 x  BODj- value of 670  gms 02/1000
bird-hrs that has been suggested (21).
                                      40

-------
Solids Management
In order to maintain an equilibrium mixed liquor total solids concentra-
tion and SRT, removal of solids was required.  The following options
were considered:
          1)  creation of a continuous flow system by water addition
          2)  liquid-solids separation via gravitational settling
The first option was not considered practical due to the volume of effluent
involved.  To maintain a 20 day SRT, 5299 £ (1400 gal) of mixed liquor
would have to be removed from each ditch daily.   This would require the
handling of 484 £  (128 gal) of wastewater per bird per year.  A 1,290,667 a
(340,995 gal) lagoon would be required to provide three months storage
of mixed liquor discharged for both oxidation ditches with this option.

Limited experience at the AWML indicated that liquid-solids separation via
gravitational settling could be a feasible method of controlling mixed
liquor total solids concentrations.  However, detailed knowledge of
aerated poultry waste settling characteristics was not available.  An
apparently conservative value of 50 percent solids removal via settling
was assumed for design purposes.  Based on expected biological removal
of total solids, (Table 7), it was calculated that daily removal of 107 kg
dry weight of total solids was necessary to maintain the desired equili-
brium conditions.  The required daily flow through the settling basin
for each ditch was calculated to be 10,720 £/day (2832 gal/day).

The design of the settling basins was based upon a number of factors.
First, it appeared desirable to combine settling with sludge thickening
and storage to simplify operation.  Therefore, volume as well as surface
area was an important design consideration.  Limitation of funds in part
constrained the maximum tankage volume that could be obtained.  The lowest
cost option in terms of cost per unit volume was 2500 gallons (9462 i)
precast concrete tanks.  The design specified four tanks per oxidation
                                                              2        2
ditch.  The four tanks for each ditch had a surface area of 5m   (54 ft  ).
                                     41

-------
 The arrows  in  Figure  8,  indicate  the direction of flow through the.tanks.
 The method  of  operation  was  to withdraw clarified liquid from the last
 tank and reintroduce  it  into the  ditch.  This created an overflow of
 mixed liquor through  a standpipe  into  the first settling tank.

 Based upon  required mixed  liquor  flow  and settling tank volume, the design
 hydraulic detention time was 3.5  days.  The calculated overflow rate was
 2163 £/day/m2  (53 gal./day/ft2).  An overflow rate of 48,975 £/day/m2
                  P
 (1200 gal./day/ft ) for  poorly settling activated sludge has been suggested
 as adequate (24). Therefore, it  appeared that sufficient settling capacity
 was available  with flexibility for  increasing overflow rates if necessary.

 The amount  of  storage time provided, and the volume of material requiring
 ultimate disposal, was a function of the degree of sludge thickening.
 Anticipated values for sludge volume on a daily basis and storage time
 are given in Table 9.

            Table  9.   DESIGN  VALUES  FOR SLUDGE STORAGE TIME
      Sludge  Concentration     Volume of Sludge     Storage Time
             (mg/£)               per day  (A)            (days)
40,000
50,000
60,000
70,000
2684
2150
1785
1532
14.1
17.6
21.2
24.7
Ultimate Disposal
The 60.7 ha  (150 acres) of crop land located adjacent  to  the  poultry
houses (Figure 4) has served as the site of ultimate disposal  for  the
wastes produced on this farm.  The available land  is used for continuous
                                     42

-------
corn production.  The corn crop is harvested as grain which is field
shelled.  Production averages 63 kg/ha  (100 bu/acre).

The ability of the available land to accept the wastes produced by the
19,000 birds located on this farm was estimated as part of the overall
project design.  The objective was to determine the level of stabiliza-
tion which would be required to prevent adverse environmental impact
from ultimate disposal of these wastes.  Both total solids and nitrogen
loadings were considered.  Based upon the assumed waste production values
(Table 5), the yearly total solids production was calculated to be
277,400 kg (611,013 Ibs).  This would result in an application rate of
4570 kg/ha/yr (4073 Ibs/acre/yr).  This value is substantially below
the level of 101 metric tons/ha/yr (45 tons/acre/yr) which has been demon-
strated to be acceptable (2).

The total nitrogen production per year was calculated to be 23,371 kg/yr
(51,478 Ibs/yr).  This would result in an application rate of 385 kg
N/ha/yr (343 Ibs N/acre/yr).  At the maximum recommended application rate
for corn of 224 kg N/ha/yr (4), it was calculated that 42 percent of the
nitrogen excreted by the birds on this farm should be removed prior to
land application to avoid potential nitrogen problems.

The consideration of some nitrogen loss by denitrification and hence the
inclusion of nitrification as a process design objective was based upon
this fact.  It was assumed that denitrification would occur during settling
and sludge storage and perhaps also in the ditches.

CONSTRUCTION
The four existing collection pits (Figures 5 and 6), were converted to
two oxidation ditches by the removal of the end walls in each pit
followed by construction of four semicircular channels.  The result was
the formation of two elongated loops.  The outer perimeter of each semi-
circular channel was formed with precast concrete silo staves.  The inner
                                    43

-------
 surface of the outer perimeter was plastered wi,th mortar to seal the
 joints between the  staves.  A concrete floor was poured in each semi-
 circular channel.

 The connecting channels  extended beyond the ends of the cage rows into
 the service alleys.   To  permit movement of feed and egg carts as well
 as personnel,  it was necessary to cover the semicircular channels.
 Pressure treated wood was used for beams and joists.  Exterior grade
 plywood  was used as flooring.

 Four interconnected  9462 s,  (2500 gal) precast concrete tanks provided
 settling and sludge  storage facilities for each oxidation ditch.  The
 tanks were located outside  the poultry house (Figure 8).  The tanks
 were interconnected  and  connected to the oxidation ditches with 20 cm
 (8 in) bituminous fiber  pipe.  Influent pipes to each tank were baffled
 to minimize turbulence.  Influent and effluent lines were alternated
 to minimize short circuiting of flow.

 EQUIPMENT SELECTION
 Two different  types  of surface aeration equipment were employed, one
 in each oxidation ditch, to evaluate alternatives for aeration of oxida-
 tion ditches.   One was a cage rotor which functioned as both an aeration
 and mixing device.   The  second aeration unit was a brush type rotor.
 Design of the  latter aerator was based on oxygenation and appeared to
 require a supplemental mixing unit.  A submerged industrial propeller
 was  used to  provide  supplemental mixing.  Equipment placement is shown
 in Figure 8.

Although  several commercial cage rotors were available, a Thrive Centers,  Inc.
 unit was  selected.   This choice was based in part on availability of
operating  characteristics as well as familiarity with a similar cage
rotor at  the AWML.   The channel width of 2.3 m (7.7 ft) limited the
maximum  length of a  single cage rotor to 1.68 m  (5.5 ft).   The  rotor,
                                      44

-------
model H-805, had a diameter of 70 cm (27.5 in) and was driven by a 3.7 kw
(5 hp) motor at a speed of 100 rev/min.  The maximum recommended immersion
depth for this unit is 15.2 cm (6 in.).

The oxygenation characteristics of the Thrive unit were not available
from the manufacturer.  However, characteristics presented by Jones,
et al. (45) and unpublished test data (46) were available.  These studies
involved rotors of the same design at a 15.2 cm (6 in) immersion depth
and resulted in the data in Table 10.

    Table 10.  OXYGENATION CAPACITY FOR THE THRIVE CENTER CAGE ROTOR
Rotor Length
  cm (in)
  Oxygenation Capacity
gms 02/m/hr (Ibs 02/ft/hr)
Reference
55.9 (22)
66.0 (26)
114.3 (45)
2150 (1.4)
2383 (1.6)
1974 (1.3)
(46)
(45)
(45)
The results are approximately equal.  Therefore, a value of 2150 gms
0?/m/hr was used for design purposes for the expected rotor size.  It
was estimated that the 1.68 m rotor would transfer 3612 gms 02/hr.   This
amount was greater than the maximum anticipated oxygen demand of 3440
gms 0?/hr thereby providing a small safety factor.  The ability of the
1.68 m rotor length to provide adequate mixing was estimated as follows.
A minimum oxidation ditch velocity not less than 0.38 m/sec (1.25 ft/sec)
has been suggested (21) to provide adequate mixing.  The pumping capacity
of the Thrive Centers cage rotor was reported (47) to be 29.3 a/sec/m
rotor length (3.4 ft3/sec/ft rotor length).  It was calculated that a
1.68 m rotor should provide a velocity of 0.44 m/sec (1.46 ft/sec) and
it appeared that the 1.68 m cage rotor was adequate in both mixing and
oxygenation capacity.
                                    45

-------
The brush type rotor manufactured by Montair, Inc. was of a new design.
It differed from conventional brush rotors in two ways.  First, round
bars were used in place of flat blades to reduce resistance when creating
turbulence for oxygen transfer.  Second, in place of multiple rows of
blades, this unit had only two rows of round bars positioned to form a
double spiral.  With this geometry only two bars strike the liquid surface
at a given instant.  This reduced the impact load on the aerator power
transmission components.  The unit sized to fit the 2.3 m (7.7 ft) Manor-
crest channel width had a rotor length of 2.1 m (6.8 ft).  It was driven
by a 1.5 kw (2 hp) gearhead motor.  Rotor speed was varied by changing
sprocket sizes.  Maximum immersion depth was 15.2 cm (6 in).

The operating characteristics of this unit, i.e., oxygen transfer and
pumping capacity, were not known.  However, it appeared that this aerator
had the potential for greater oxygen transfer efficiency expressed as
gms CL per kwhr.  Another apparent advantage was the light weight of the
aerator which would facilitate maintenance and repair when necessary.
Since the pumping capacity of this aerator was questionable, supplemental
pumping was provided by a 38.4 cm (15.1 in) industrial propeller driven
by a 2.2 kw (3 hp) variable speed motor.  The propeller had a design
pumping capacity of 15,500 £/min (4095 gal/min) at the maximum speed of
350 rpm.  It was estimated that the propeller would provide a supplementary
liquid velocity of 0.2 m/sec (0.7 ft/sec) at a 50.8 cm (20 in) liquid
depth.  This combination of the brush aerator and propeller was installed
in Ditch I while the cage rotor was used in Ditch II.  Two small 0.4 kw
(0.5 hp) helical screw pumps were specified to recycle settling tank
effluent.
                                     46

-------
                              SECTION V
                        METHODS AND MATERIALS
OXYGEN TRANSFER
The oxygen transfer capacity of both aeration units in tap water was
determined at the outset of the evaluation phase of the study.  The
tests were conducted between the completion of construction and equip-
ment installation and the initial operation of the ditches as treatment
units.  The non-steady state chemical method (39) was used.  Sodium
sulfite (Na2S03) in the presence of a catalyst, cobalt chloride (CoCl2),
was used to deplete the dissolved oxygen concentration.  The cobalt
chloride was added to achieve a concentration of 0.2 mg/a in the tap
water in each ditch.  Both chemicals were dissolved prior to addition.
Manual mixing was employed in an effort to achieve uniform chemical
distribution.

Following the commencement of aeration, the rate of increase of the
dissolved oxygen concentration was measured with YSI model 54 dissolved
oxygen meter.  The meter was standardized against saturated distilled
water at a known temperature and atmospheric pressure.  Saturated oxygen
concentrations were obtained from Standard Methods (48)-  The temperature
of the tap water was measured at the time of these tests.

The oxygen transfer coefficient, KLa, was computed using the following
equation:
                            dc _
                            dt ~
where     dc  _
T£  = change in dissolved oxygen concentration with time

K, a = overall oxygen transfer coefficient, time"

C   = oxygen saturation concentration, mass/volume

C.   = dissolved oxygen concentration at time t, mass/volume
 L
                          47

-------
 K a  was  determined  from semi -logarithmic plots of the oxygen deficit,
 C -Ct, versus  time.  A least squares exponential regression program was
 used to  fit a  straight line to the experimental data and calculate the
 slope of the line,  KLa.

 The  values of  C  were obtained from Standard Methods (48) and corrected
 using local barometric pressure readings obtained from the U.S. Weather
 Bureau,  Hancock  Field, Syracuse, New York.  Hancock Field is located
 approximately  twenty miles from the demonstration site and is at the
 same elevation.  The following equation was used to calculate the actual
 value of C .

 C (actual) =  [Cq (tabular value)] Local Atmos. Pressure (in Hg.)   (15)
  ->               i>                           Cy . yc. I n ng .
 All  K.a  values were corrected to 20°C using the following relationship.

                       KLaT = KLa20oC(e)(T-20)                      (16)

 where    K,_aT    = yalue Qf     at rc
          KLa20°C = Va1ue °f KLa at 20°C
          e       = temperature correction factor, 1.02
Equation 11,  (Section III), was used to calculate the mass of oxygen
transferred per unit time.

VELOCITY MEASUREMENTS
The velocity of tap water in each oxidation ditch was measured with a
Gurley model number 622 current meter.  This was a direct acting current
meter.  Velocity measurements were made at two locations in each ditch
as indicated in Figure 9.  To determine the average velocity in each
cross-section, measurements were made at the locations indicated in
Figure 10.   The results were averaged vertically and then horizontally
to obtain the average velocity at each location.
                                  48

-------
                          AERATION  UNIT

X
LOCATION
Jf*
           c
                 LOCATION
                                   FLOW
     Figure 9.  Location of velocity measurements,  plan view
                         .21
             X  _
             x  —   _ _jc_- .-   .    x 	=?-
                                                  X
                                                  re
    -1/4 D
1/4 D
1/4 D
1/4 D
Figure 10.  Location of velocity measurements, cross section
                              49

-------
 Attempts  were  made  to measure ditch velocity under process conditions.
 Both  the  current meter and a subsurface float were used.  The cups on
 the current meter became fouled with feathers which eliminated this
 approach.  The subsurface float was also unreliable due to cross-
 currents  a'nd accumulated sediments.  No reliable data were obtained
 with  respect to velocity under process conditions.

 One important  aspect of the oxygen transfer studies was to compare the
 efficiency of  the two aeration systems.  This normally is done by
 measuring energy consumption and expressing efficiency as mass of oxygen
 transferred per unit energy consumed.  However, electric motor efficiency
 increases as loading approaches the design maximum.  For a given motor,
 the ratio of power  consumed to power produced will be less at lower
 than  design loadings.

 In order  to eliminate this variable and thus provide an equal basis for
 comparison, the shaft power was determined for each motor under the
 various test conditions.  This was accomplished by measuring energy
 consumption of each motor with commercial type watt-hour meters.  These
 data  were then translated into shaft power using motor performance curves.
 Performance curves  were obtained from the manufacturers of the motors
 supplied with  the brush and cage aerators.  Performance curves for the
 propeller drive, which consisted of a variable speed DC motor and gear
 reducer, were  not available from the manufacturer.  Therefore, dynamometer
 tests were performed to develop performance curves.  The performance
 curves that were used are presented in Figures 1 through 4 of the appendix.

 DATA  COLLECTION
 To perform materials balances and to determine the degree of waste
 stabilization,   routine sampling of fresh wastes, oxidation ditch mixed
 liquor (ODML),  and  settling tank supernatant returned to the ditches
was conducted  through the course of the study."  A 24 hour, composite
sample of raw manure was collected weekly from randomly selected groups
                                     50

-------
of four hens.  The raw manure was collected by suspending a tray below
an individual cage.  Grab samples of ODML and return supernatant were
taken twice a week.  All samples were returned to the AWML and analyzed
on the day of collection.

The raw waste samples were analyzed for the following parameters:
          Total manure production per bird-day
          Total solids
          Volatile solids
          Chemical oxygen demend (COD) - total and soluble
          Total Kjeldahl nitrogen (TKN)
The mixed liquor and settling tank supernatant were analyzed for the
following:
          Total solids
          Volatile solids
          COD - total and soluble
          TKN
          Ammonia nitrogen (NH*-N)
          Nitrite nitrogen (N02-N)
          Nitrate nitrogen (NOg-N)
          PH
          Temperature
          Dissolved oxygen (D.O.) - mixed liquor only
ANALYTICAL METHODS
Total and volatile solids were determined as described in Standard Methods
(48).  TKN was determined by a micro-Kjeldahl method (49).  Ammonia nitro-
gen was determined using the stream distillation procedure (50).  Nitrite-
nitrogen was determined by diazotization (51).  Nitrate-nitrogen was
described by a salicylic acid method (50).  The rapid method (52) was
used to measure COD.  Soluble COD was defined as that portion of the total
COD that would pass through a 0.8 y millipore filter.  The presence of
nitrifying organisms, Nitrosomonas and Nitrobacter, was determined using
                                    51

-------
 a  procedure  for estimation of active nitrifying organism concentrations (53).
 Dissolved oxygen concentration and temperature of the mixed liquor were
 measured in  the ditches at the time of sampling with a YSI, model 54
 oxygen  meter.  Dissolved oxygen concentrations were measured at the
 locations indicated  in Figure 8 to provide a profile of dissolved oxygen
 concentration  in relation to distance from the aeration unit.  The oxygen
 uptake  rate  was determined by aerating a mixed liquor sample and then
 measuring the  decrease of dissolved oxygen with time.

 Zone  settling  velocity was determined by measuring the downward movement
 of a  sample  mixed liquor-supernatant interface with time.  The tests
 were  conducted in a  1 £ graduated cylinder.  Samples were not stirred.

 CALCULATION  OF SRT AND TREATMENT EFFICIENCY
 The conventional approach to calculation of SRT is based upon the follow-
 ing relationship.
             _R_ _     wt. of solids in the system	            ,r\
                   wt. of solids leaving the system/time            ^ '
 It is implied  in this method of calculation that all of the solids
 leaving the  system are lost in the effluent, and that they can be
 measured.  However,  in the Manorcrest oxidation ditches, solids were
 removed from the system in two ways.  One method of removal was by the
 intentional  settling of mixed liquor.  The other was via uncontrollable
 sedimentation  in the ditches.  Although it was possible to measure the
 solids  lost  through  the settling tanks, accurate determination of solids
 lost via sedimentation was not possible.

 The problem  of sedimentation required a different approach to the calcu-
 lation of SRT.  Although suspended solids are commonly used in the cal-
culation of  SRT, use of total, volatile, or fixed solids is also valid.
In any given system, constant relationships should exist between these
types of solids.  At equilibrium, the fixed solids entering the system
should equal those  leaving the system assuming fixed solids generated
                                     52

-------
or lost during treatment are minimal.  This permitted a different
approach to the calculation of SRT.  It was possible to accurately deter
mine the quantity of fixed solids entering the system.  By assuming the
quantities of fixed solids entering the system were equal to those
leaving the system by any physical means, it was possible to estimate
SRT as follows:
        SDT =	wt. of fixed solids in the system	
              wt. of fixed solids entering the system/unit time
This was the approach used to determine SRT in this study.  Mixed liquor
fixed solids concentrations were used to determine when equilibrium
conditions were attained.

Equation 18 defines treatment efficiency in terms of influent and
effluent waste characteristics.
                              Sn - S,
                          E =-n-	L (100)                         (18)
                                ^o
where     E = treatment efficiency, percent
         S  = influent waste characteristic
          o
         S, = effluent waste characteristic

In a completely mixed system, the mixed liquor and effluent should have
the same characteristics and either concentration can be used.  This
equation can be used in several ways.  The most common is to express
S  and Sn as concentrations, mass per unit volume.  A second approach
is a total mass balance with S  and S, representing total mass in and
out of the treatment system.  A third method is based on the ratio of
any given parameter such as total and volatile solids, organic nitrogen
and COD to a constant factor such as fixed solids in both raw and stabilized
waste.  The latter was the approach used for the calculation of treatment
efficiencies in this study.

The following is an example of this method of calculation of treatment
efficiency.  Ratios of a given parameter to fixed solids in the raw
                                     53

-------
 wastes  and mixed  liquor  were  calculated from analyses to determine
 concentration  per unit volume of  both the parameter and fixed solids
 in each sample.   The  fixed  solids  ratio  was then calculated as follows:
                                Concentration of parameter,
          Fixed solids ratio,  _ 	mass/volume	         /ig^
             mass/mass         Concentration of fixed solids         ^   '
                                        mass/volume
 The ratio calculated  from raw manure analyses represented S  in Equation
 18 while S-|  was the ratio calculated from results of mixed liquor analyses.
 The difference between S and S-,  represents biological removal from  the
 system.

 Either  the first  or third method  could have been used to estimate treat-
 ment efficiency.   The inability to accurately determine losses via sedi-
 mentation eliminated  the total mass balance approach.  The fixed solid
 ratio approach was selected because it was similar to the means of SRT
 estimation in  that both  are based  on fixed solids.  This approach provided
 a  simple and rapid method of  monitoring system performance.

 ECONOMICS
 Capital  costs, building  modifications and equipment were amortized at an
 interest rate  of  9 percent  to  determine annual costs.  Time periods  used
 are as  follows:
                   Structures             20 years
                   Aeration Equipment     10 years
 Energy  consumption was continually measured for each electric motor  in
 order to  determine energy costs.   Where operating conditions resulted
 in  motor  loadings that were below  values which produced peak motor
 efficiency,  corrections  in measured energy consumption were made to  de-
 termine energy consumption at  peak motor efficiency.  This was done  when
operating  conditions were such that the electric motor was significantly
 underloaded  and could have been replaced with a smaller size motor.  The
motor performance curves (Appendix, Figures 1 through 4) were used for
                                    54

-------
this purpose.  The measured input energy was used to determine energy
output.  This value was then used to calculate energy consumption at
the peak motor efficiency for that motor as indicated in the performance
curves.  The variable speed D.C. motor for the propeller drive had a low
peak efficiency, 62 percent, in comparison to an A.C. motor.  Since a
variable speed D.C. motor normally would not be used, the value of 70
percent, which is realistic for an A.C. motor, was used in the case of
the propeller.  The electrical energy cost to Manorcrest Farms through-
out the study remained constant at $0.0201 per kilowatt hour.  This
included the fuel adjustment charge as well as the base rate.
                                    55

-------
                              SECTION VI

                      SYSTEM PERFORMANCE RESULTS
 INTRODUCTION
 The  project  "Demonstration of Aeration Systems for Poultry Wastes"
 covered  the  period from March 1973 through June 1975.  Details of the
 major  phases of the study are contained in Table 11.


     Table  11.  AN OUTLINE OF THE MANORCREST DEMONSTRATION ACTIVITIES


           Time Period                     Activities

         March - May 1973          System design and equipment
                                  selection and acquisition
         June - August 1973        Construction, electrical work
                                  and equipment installation
         August 1973               Oxygen transfer studies
         September 1973 -          System operation for demonstration
         March 1975               and evaluation
         March - June 1975         Detailed analyses of data;
                                  preparation of final report

It was necessary to integrate the construction activities and the oxygen
transfer studies with the replacement schedule for the chickens located
in Building No. 1.  This resulted in the extended period for design
and construction.

The initial operating conditions for each oxidation ditch are presented
in Table 12.

                                    56

-------
          Table 12.  SUMMARY OF INITIAL OPERATING CONDITIONS,
                     SEPTEMBER 1973
                                 Ditch I            Ditch  II
     Bird number                  4,000              4,000
     Volume                     105,980 i          105,980 a
                                (28,000 gal)       (28,000 gal)
     Liquid depth                 50.8 cm            50.8 cm
                                  (20 in)            (20.1n)
     Aeration unit
          Speed                   252 rpm            100 rpm
          Immersion depth         15.2 cm            12.7 cm
                                  (6 in)             (5 in)
     Propeller speed              232 rpm
     Oxygen transfer          1403 gms Op/hr     3360 gms 02/hr
       capacity
Over the 19 months that the aeration systems were monitored,  several
changes in operating conditions were instituted.   These changes  are
listed in Table 13.  The aerator speed in Ditch I was increased  to
evaluate system performance at a higher level of oxygen transfer.  The
resulting increase in mixed liquor velocity due to increased  pumping
by the aerator made the propeller expendable.  Since the propeller
housing was impending foam movement and causing a significant sediment
accumulation, it was removed.   The reason for the reduction  in  liquid
depth was to increase mixed liquor velocity to reduce sedimentation.
This problem will be discussed in greater detail  at a later point.

This section contains the experimental results of the study.   Included
are results of the oxygen transfer and velocity studies, system
performance, system costs, and identification of problem areas.
                                  57

-------
               Table  13.  CHANGES IN OPERATING CONDITIONS
          Date                          Change
         1/7/74         Aerator speed in Ditch I increased
                       to 310 rpm.  Immersion depth decreased
                       to 11.4 cm  (4.5 in.).
         1/17/74        Propeller in Ditch  I was removed
         9/1/74         Volume of each ditch reduced to
                       68,887 £ (18,200 gal.).  New liquid
                       depth was 33 cm (13 in.).
 OXYGEN TRANSFER STUDIES
 Oxygen transfer studies were conducted in both ditches following the
 completion of construction and equipment installation.  The specific
 objectives of these studies were to:
          1)  establish baseline oxygen transfer data
          2)  evaluate the brush aerator-propeller combination as
              an alternative aeration approach
 The scope of these studies was restricted  by two factors.  First, the
 cages were empty during construction and only a limited time period was
 available prior to the housing of new birds.  Second, the flow rate of
 the farm water supply was limited.  Therefore, it was necessary to
 purchase water to run these tests.  Thus, only one filling of each ditch
 was possible.  The results reported were limited to the data obtained
 from the first 10 trials, although 12 tests were conducted in each
 ditch.  The data collected during the llth and 12th trials were of poor
quality.   Accumulation of salts or other contaminants was the probable
cause of this phenomenon.  Problems resulting from poor mixing of the
chemicals with the tap waterand leakage in Ditch II reduced the usable
data to that collected during 4 of the 12 trials.
                                   58

-------
Ditch I
The aeration system in this ditch was the experimental brush aerator and
the propeller mixer.  The relationship of two variables, brush aerator
speed and velocity of ditch contents, to oxygenation efficiency was
examined in this ditch.  The test conditions included two brush aerator
speeds, 126 and 252 rpm at a constant immersion depth of 15.2 cm (6 in).
Propeller speeds included 0, 115, and 232 rpm.  Cavitation limited the
maximum propeller speed to 232 rpm.  Both oxygen transfer and velocity
measurements are presented in Tables 14 and 15 respectively.  Shaft
power, kilowatts, or horsepower were obtained from energy consumption
data and motor efficiency curves.

The results presented in Tables 14 and 15 show the relative impact of
each device on both oxygenation and pumping efficiencies.  The propeller
did not perform any aeration.  Increased propeller speed, and therefore
ditch velocity, decreased the oxygenation efficiency per unit of power
utilized.  Peak pumping efficiency did not occur when the propeller was
used alone.  Although the data indicates that the propeller was more
efficient than the brush aerator for pumping, the most effective situa-
tion was the combination of the 126 rpm aerator speed and the 115 rpm
propeller speed.  This combination also had the highest oxygenation
efficiency, 1684 gms 02 per kw-hr.

However, oxygen transfer was only 527 gms 02 per hour or 132 gms 02 per
1000 bird-hours for 4000 birds.  This value was significantly below value
for odor control of 470 gms 02 per 1000 bird-hours (Table 8).  Consequently,
the combination of the 252 rpm aerator speed and the 232 rpm propeller
speed which provided 351 gms 02/1000 bird-hours was used for initial
phase of Ditch I operation.
                                     59

-------
      Table  14.   RESULTS OF OXYGEN TRANSFER MEASUREMENTS - DITCH I

Test Condi
RPM
Aerator -
Propeller
Aerator -
Propeller
Aerator -
Propeller
Aerator -
Propeller
Aerator -
Propeller
tions,
252
- 232
252
- 0
126
- 232
126
- 115
0
- 232
K, a^Q Gms Op/
Min-1 Hr.
.024 1403

.024 1403

.011 616

.009 527

- 0

Shaft Power, Gms 02/
Watts KwHr
.947 918
.582
.947 1482
0
.306 694
.582
.306 1684
.700
.582

 Ditch  II
 Rotor  immersion depth was the variable examined in this oxygen transfer
 study  of the cage rotor.  Trials were conducted at two immersion depths,
 7.3 and 12.7 cm (2.9 and 5 in.).  The results of these trials are noted
 in Tables 16 and 17.  The cage rotor had a greater oxygenation and pump-
 ing capacity than the system in Ditch I.  However, both oxygenation and
 pumping efficiencies were lower.  Therefore, higher operating costs per
 unit oxygen transferred could be expected for this system.

 The results of cage rotor oxygen transfer measurements are compared to
 results of other studies in Figure 11.  The other studies also involved
 Thrive Centers cage rotors of the same design as the Manorcrest unit.
As shown in the Figure, there is good general agreement between the
Manorcrest results and those of the other investigations.  It appears
                                   60

-------
                        Table 15.   RESULTS OF VELOCITY MEASUREMENTS - DITCH I

Aerator
Speed,
RPM
126
126
126
252
252
0
Propeller
Speed,
RPM
0
115
232
0
232
232
Average
Velocity,*
m/sec
0.06
0.12
0.24
0.15
0.26
0.11
Pumping
Capacity,
a/sec
71
142
285
178
309
130
Shaft
Power,
Watts
306
313
887
947
1529
582
Efficiency
£/sec/watt-hr
.232
.454
.321
.188
.202
.223
*Average of velocities measured at locations 1 and 2 (Figure 9)

-------
               Table 16.  RESULTS OF OXYGEN TRANSFER MEASUREMENTS - DITCH II
Immersion Depth,
cm (in.)
7.3 (2.9)
12.7 (5)

KLa2Q Gins 02/hr Gms 07/meter
m1-n-l of rotor length
0.036 1925 1148
0.062 3360 2005
Table 17. RESULTS OF VELOCITY MEASUREMENTS -
Shaft Power,
watts
1678
2759
DITCH II
Efficiency
Gms 02/KwHr
1147
1218


Immersion Depth,
cm (in.)
Average Velocity, Pumping Capacity
m/sec £/sec
Shaft Power,
watts
Efficiency,
^/sec/watt
12.7 (5)
0.38
458
2759
.166

-------
               167.6 cm ROTOR, MANORCREST FARMS

               66 cm ROTOR ,  JONES, et a I. (45 )

               55.9 cm ROTOR, MARTIN (46)

               116.8 cm ROTOR, JONES, et. al. (45)
O
QC
O


(T
L_
O
I
QC
LJ
    2600
    2400
    2200
    2000
    1800
O  1600
bJ

"*  1400
    1200
    1000
6    800
o

     600
    400
                  1
                             I
                 5.08      10.16       15.24      20.32

                    IMMERSION  DEPTH , cm

        Figure 11.  Comparison of oxygen transfer characteristics,
                  Thrive Centers cage rotors
                            63

-------
 that  the differences are due to factors such as ditch size and geometry
 which varied.

 At  the  12.7 cm  (5 in.) rotor immersion depth, oxygen transfer was 3360
 gms Op  per hour or 840 gm Op per 1000 bird-hours for 4000 birds.  This
 value was comparable to the design value of 860 gms Op/1000 bird-hours
 for odor control plus nitrification (Table 8).  Therefore, this
 immersion depth was used under operating conditions.

 RAW WASTE QUANTITIES AND CHARACTERISTICS
 The laying hens involved in this study were a commercially available
 breed white leghorn chickens, the Shaver strain.  The period of oxida-
 tion  ditch operation exceeded one laying cycle.  Since these birds were
 replaced at the end of the first cycle, 12 months, two groups of birds
 were  involved in this study.  The first group was housed in September
 1973, concurrent with the start operation of the oxidation ditches, and
 the second in September 1974.  The birds were 20 weeks of age and had
 started egg production when placed in the cages over the oxidation ditches,

 There was no major change in the mass or characteristics of the manure
 with  increasing bird age.  Therefore, each year's results were averaged
 and are presented in Table 18.  Only small changes in waste characteris-
 tics occurred between the two years.  These variations could have been
 due to  changes in feed.  No feed analysis information was available,
 since most of the feed is manufactured on the farm from home grown grains.
 Noticeable changes were the 11.4 percent increase in COD and the 12
 percent increase in fixed solid production per bird-day in 1974-75.

 The observed quantities and characteristics of the raw manure are signi-
 ficantly lower than the values assumed for design (Table 5).  Due to the
 lower loading rates, the design safety factor was greater than  that
originally estimated.  Precise reasons for the difference in raw waste
characteristics are unclear.  Two factors are possible differences  in
                                    64

-------
Table 18.  RAW MANURE CHARACTERISTICS, MANORCREST FARMS


gms TS
bird-day
gms VS
bird- day
gms FS
bird- day
0/ vs
/0 TS
gms COD
bird- day
gms TKN
bird -day
gms BOD5
bird-day
BOD5
COD
% Soluble COD
mg COD
gm FS
mg TKN
gm FS
3ms VS
gms FS
1973-74
29.6
22.1
7.5
74.8
19.2
2.3
4.9
.26
24.5
2565
307
2.9
1974-75
29.0
20.6
8.4
72.0
21.4
2.2
23.3
2544
263
2.4
                           65

-------
 diet and  the  strain of bird.  The values used for design were obtained
 from Babcock  white leghorn chickens.

 SYSTEM PERFORMANCE
 Introduction
 The  rationale of  using SRT as a design and operational parameter for
 slurry type biological treatment systems was discussed in Section III
 and  used  in the design of these aeration systems.  In order to confirm
 or nullify the validity of this approach, system performance was evaluated
 at several different SRT's.  In addition, the differences in oxygenation
 capacity  of the two aeration systems  (Table 12) provided comparison of
 two  different levels of oxygen transfer.  The increase of the brush
 aerator speed (Table 13) provided a third level of oxygen transfer.  The
 relationships between quantity of oxygen supplied to both waste stabiliza-
 tion and  nitrogen transformations were examined.

 Physical  design and mechanical difficulties limited the number, and in
 some cases, the length of equilibrium SRT conditions.  Accumulation of
 sediments in  both ditches was one serious problem.  It was necessary to
 completely empty each ditch on two occasions.  This will be discussed
 later in  greater detail.  Mechanical problems resulted in the stopping
 of the  Thrive rotor for periods exceeding 24 hours on at least eight
 occasions.  Operation of the brush aerator was also interrupted several
 times.  These occurrences either interrupted equilibrium conditions or
 prolonged the time period necessary to reach steady-state.

 General
Throughout the course of the study, both aeration systems provided  a
high degree of odor control. This was true at all three levels of oxygena-
tion and the various SRT's evaluated.  At the lowest level of oxygen
transfer, 351 gms OM per 1000 bird-hours, the odor of ammonia due to
ammonia stripping was detectable in the immediate vicinity of the
                                    66

-------
aeration unit.  No waste associated odors were present in other areas
of the building or in the ventilation exhaust air streams when continuous
aeration was provided.  Malodors did occur following restart of aeration
units after mechanical problems.  However, reestablishment of odor control
was accomplished within approximately three to six hours depending on
the length of aerator shutdown.  The longest breakdown period was four
days.  No other vermin problems were observed.

The only point in these two systems where trial odors were generated was
in the settling and sludge storage tanks.  Although odors were evident
when sludge was being removed for ultimate disposal, the intensity was
not of sufficient magnitude to create any problems during pumping or
field spreading.  In addition to door control, the presence of house flies,
Musca domestica, which breed in animal manures, was essentially eliminated.
There was no need to use any fly control measures through the course of
the study.

Relationship erf SRT tp^ Treatment Efficiency
To demonstrate and quantify the relationship between SRT and treatment
efficiency with respect to aerated poultry wastes, treatment efficiencies
at six different SRT's were determined.  SRT was varied by controlling
the rate of solids removal in the settling system.  Precise selection
of SRT was not possible due to problems in liquid-solids separation
which will be discussed later.  This accounts for the non-uniform distri-
bution of SRT's which ranged from 10.5 to 36.5 days.  However, it was
possible to establish steady-state conditions at six different SRT's.
Removals of total and volatile solids, COD, and organic nitrogen were
calculated for each period.

Relationships between SRT and the percentage removal of each parameter
are presented in Figures 12 and 13.  These results show that as SRT
increased, removal of each parameter also increased.  Details of each
equilibrium period are given in Table 1 of the Appendix.
                                    67

-------
   60 r—
    50
<  40
O
   30
(T
   20

    10
                           •  TOTAL  SOLIDS
                           *  VOLATILE SOLIDS
                10        20        30
                       SRT, days
                                              40
   Figure 12.
             Observed relationships between SRT and removal of
             total and volatile  solids
   70

   60
<
>  50
Id
or
o**
   40

   30

   20 —

    10
                10
                            * ORGANIC NITROGEN
                            • COD
                           I          I           I
                          20         30
                        SRT,  days
40
 Figure 13.  Observed relationships between SRT and removal of
            organic nitrogen and  COD
                          68

-------
Relationship of_ Oxygen Supply tp_ Process Performance
The Manorcrest oxidation ditches were operated at three different levels
of oxygen transfer in order to develop a relationship between oxygen
supply and process performance.  The three levels were 350, 520, and
840 gms 02 per 1000 bird-hours.  For purposes of simplicity, these three
levels of oxygen transfer capacity will be referred to as Levels I, II,
and III.  Due to the relationship of mixed liquor total solids concentra-
tions to a (Figure 2), estimated oxygen transfer for the three SRT's at
Level III were less than the tap water value of 840 gms 02 per 1000 bird-
hours.  This was not due to any changes in system operation.  These
Levels were examined concurrently with SRT in order to correlate oxygen
input with treatment efficiency.

The absence of malodors indicated that the exerted carbonaceous oxygen
demand was satisfied aerobically even at the lowest level of oxygen in-
put.  Comparison of carbonaceous oxygen demand satisfied expressed as
COD removed with the oxygen transferred under process conditions is
presented in Table 19.  Oxygen transferred under process conditions was
calculated using the relationship between mixed liquor total solids
concentrations and a presented earlier (Figure 2).  The quantity of COD
removed was based on the calculated treatment efficiency for each
detention time.

The conclusion that the exerted carbonaceous oxygen demand was being
satisfied as indicated by odor control is substantiated by these values.
In all cases, the rate of oxygen transfer exceeded the rate of COD
removal.  These data indicate that treatment efficiency, i.e., total and
volatile solids, COD, and organic nitrogen removal, was not limited at
any time by the lack of available oxygen.  The variations in the rates
of COD removal appear to be related to changes in SRT.

Average dissolved oxygen concentrations (DO) for the range of conditions
studied are given in Table 20.  The designations 1/4 and 3/4 point
                                    69

-------
                       Table 19.  COMPARISON OF COD REMOVED WITH OXYGEN SUPPLY

Level of
Oxygen Transfer
I
II

III


SRT,
Days
15
21
10.5
18
27
36.5
Total Solids
Concentration,
mg/£
9,960
13,550
13,760
21,570
19,800
23,830
a
Factor
1
1
1
0.95
0.97
0.94
Oxygen*
Transferred
gms/1000 bird-hr
351
520
520
798
815
790
gms COD Removed/**
1000 bird-hrs
263
250
200
322
251
280
* Calculated oxygen transfer under process conditions
**Calculated from raw waste characteristics and removal results

-------
              Table 20.   DISSOLVED OXYGEN CONCENTRATIONS

Average dissolved oxygen
concentration, mg/£
Level of
Oxygen transfer
gms 02/1QOO bird-hrs
350
520
520
798
815
790
SRT
Days
15
21
10.5
18
27
36.5
1/4
(0.7
(0.5
(0.6
(1.0
(1-4
(1.4
Point
1-0
- 1.55)*
1.0
- 1.6)
1.1
- 1.5)
1.5
- 1.8)
4.5
- 7.3)
2.6
- 4.8)
3/4
(0.1
(0.1
(0.2
(0.3
(0.4
(0.4
Poi nt
0.25
- 0.4)
0.3
- 0.5)
0.2
- 0.3)
0.4
- 0.6)
3.9
- 6.9)
1.4
- 3.2)
Temp.
°C
13
12
13
16
13
13
*Range of values
                                    71

-------
indicate the distance downstream from the aeration unit at which the DO
measurements were made (Figure 8).  The relatively high DO levels at the
3/4 point for the 27 and 36.5 day SRT suggest that the DO of the mixed
liquor entering the rotor may not have been zero.  Therefore, the quantity
of oxygen transferred would have been less than the values stated in
Table 20.  The calculated quantities of oxygen transferred were based
upon a maximum oxygen deficit, C<. - C. , where C,  is zero.  This indicates
that the total oxygen demand, carbonaceous and nitrogenous, was less
than the maximum potential oxygen supply from the aeration unit.

Removal of Soluble COD
The removal of the soluble fraction of total COD in poultry wastes by
aeration was examined at four different SRT's.  As shown in Table 21,
observed removals varied but always exceeded 85 percent.  These data
indicate that the major portion of soluble COD removal from poultry
wastes in aeration systems will occur at SRT's of 10.5 days or less and
corroborated the data shown in Table 2 and Figure 1.

              Table 21.  OBSERVED REMOVAL OF SOLUBLE COD
            Level of           SRT,        Removal of Soluble
        Oxygen Transfer        Days           COD, Percent
               I                15               86.8
              II                10.5             93.8
                                21               95.7
             III                27               92.5
                                36.5             90.4
                                    72

-------
RESULTS
Nitrogen
The systems design identified nitrogen removal as a necessary design
objective for Manorcrest Farm No. 2.  Two areas involving nitrogen re-
moval were examined.  The first concerned the determination of whether
or not seeding is necessary to establish a population of nitrifying
organisms.  Included in this area were patterns of nitrification.  The
second was to compare nitrogen removal at different levels of oxygen
transfer.  Comparison included both method and extent of nitrogen removal.

Seeding and Patterns of_ Nitrification -
Each oxidation ditch was thoroughly cleaned to remove any residue from
previous manure accumulations before the oxygen transfer studies.  Neither
ditch was intentionally seeded with nitrifying organisms prior to commence-
ment of operation under process conditions.  In Ditch II, nitrification,
as indicated by the presence of nitrites (NCU-NK was first observed on
the Nth day of operation (Figure 14).  Sweeping of material on the
building floors into both ditches during routine cleaning may have intro-
duced the nitrifying organisms.

During the start-up period, days 0 through 74, Ditch II was operated as
a continuously loaded, batch reactor to build the microbial population
and to reach the desired mixed liquor total solids concentration.  Mixed
liquor concentrations of ammonia (NH,-N), nitrite (NO?-N), and nitrate
(NOo-N), plus pH for this time period are presented in Figure 14.
Following the onset of nitrification, this period was characterized by
high concentrations of NCL-N in comparison to NO--N.  Nitrification
reduced the initial accumulation of NH,-N, but NH.-N concentrations
          
-------
 8.0


 7.0


 6.0
600
              10
20
30        40
  TIME, doys
50
60
70
                    Figure 14.   Nitrogen transformations during the start-up
                               period, Ditch II

-------
NOp-N accumulation reoccurred (Figure 15).  Solids removal to achieve
equilibrium conditions started on day 81.  Therefore, Ditch II was no
longer a continuously loaded batch system.  Aeration was again inter-
rupted on two occasions as noted.  Significant denitrification was not
observed during or after either of these  latter non-aerated periods.

Only data from two periods of nitrite accumulation are presented here.
However, the same phenomenon was observed on several other occasions
following aerator breakdowns and when Ditch II was restarted for the
second year.  Unfortunately, aeration could not be continuously
maintained for a sufficiently long time period to determine if complete
nitrification, accumulation of NOo-N, would occur.  Aerator mechanical
                                 O
problems were the cause for the frequent interruptions in aeration.

Nitrogen Removal
The removal of total nitrogen was examined in relation to the three
levels of oxygen transfer previously described.  Comparison of removal
of total versus organic nitrogen and the details of operating conditions
for four steady-state periods are presented in Table 22.  Losses of
total nitrogen ranged between 48.8 and 63.3 percent under the various
conditions.  Both ammonia desorption and nitrification-denitrification
were observed as mechanisms of nitrogen removal.  Desorption occurred
at the lowest level of oxygen input with nitrification-denitrification
occurring at the higher levels.  The following sections contain the
results obtained at each level of oxygen input.

a_ - Nitrogen removal at 351 grns CL per 1000 bird-hours - At this level of
oxygen input, significant nitrification, as identified by measurements of
NO£-N or NOo-N concentrations above trace levels, was not observed.   Active
mass determinations established that both Nitrosomonas and Nitrobacter
were present although in low numbers.  Insufficient oxygen, as evidenced
by low mixed liquor dissolved oxygen concentrations  (Figure 16) and not
                                    75

-------
 8.0]

 7.0

 6.0
600 —
                                                     NO AERATION
                          BALANCE PERIOD
                                   II         121
                                       TIME, days
                  Figure 15.   Reoccurrence of nitrite accumulation in Ditch II

-------
- 2.0|—
                 61
71          81

 TIME, days
91
101
     Figure 16.   Dissolved oxygen concentrations in Ditch  I at the
                 oxygen transfer capacity of 351 gms 02/1000 bird-hours

-------
 the  absence of the microorganisms, was the probable cause for the lack of
 significant nitrification.

 During  this time period, the average mixed liquor ammonia concentration
 was  1265 mg/£ at an average pH of 8.1.  The average free ammonia (NHg-N)
 concentration was 43.7 mg/£.  This relatively high free NHg-N concentra-
 tion and the strong odor of ammonia in the immediate vicinity of the
 aeration unit suggests that ammonia stripping was the major method of
 nitrogen removal at this level of oxygen input.  Mixed liquor concentra-
 tions of total and free ammonia plus pH are presented in Figure 17.

        Table 22.  RELATIONSHIPS BETWEEN OXYGEN TRANSFERRED AND
                   REMOVAL EFFICIENCIES OF ORGANIC AND TOTAL NITROGEN

Removal Efficiencies, %
Oxygen Transfer
Capacity
gms/1000-bird-hrs.
351
520
815
790
SRT, days
15
21
27
36.5
Organic
Nitrogen
55.0
60.4
64.7
63.3
Total
Nitrogen
48.8
60.4
47.7
63.3
As shown in Table 22, the removal of total nitrogen was less than that
for organic nitrogen during the balance period.  The difference was due
to the increase of ammonia in the total system, oxidation ditch plus
settling tanks, over the balance period.  This was due to increased
ammonia concentration in the contents of both the ditch and settling
tanks.  Refilling the settling tanks with tap water following sludge
removal on day 78 added to the ammonia storage capacity.  Table 23
shows the increase in mass of ammonia in the total system with time.
                                    78

-------
  X
   Q.
     8.5
     7.5
St

-------
       Table 23.  CHANGE IN MASS OF AMMONIA NITROGEN IN DITCH I
                  AT 351 QMS 0  TRANSFERRED/1000 BIRD-HRS

Day
51
55
62
6b
69
75
78
83
87
92
99
106
Mixed Liquor
Ammonia-Nitrogen,
kg.
131.3
133.5
1 31 . 3
126.1
133.5
141.4
136.5
128.3
135.3
127.6
141.4
141.7
Settling Tank
Ammonia-Nitrogen,
kg.
37.1
41.6
45.0
45.8
48.2
50.5
0*
44.5
46.6
46.6
48.0
51.4
Total Mass,
kg.
168.4
175.1
176.3
171.3
181.7
191.9
136.5
172.8
182.4
174.2
189.7
192.8
*Settling tanks emptied and refilled with tap water
                                  80

-------
]D - Nitrogen removal at 520 gms 02 per 1000 bird-hours - Following the
period of lowest oxygen input, the level of oxygen transfer in Ditch I
was increased from 351 to 520 gms 02 per 1000 bird-hours.  Significant
nitrification occurred, as evidenced by a continuous reduction of the
mixed liquor ammonia concentration (Figure 18).  Trace amounts of NO?-N
were present in the mixed liquor throughout this period but NO,-N was
                                                              O
not observed.
Although some of the nitrogen loss can be attributed to ammonia stripping,
the potential for desorption decreased with time as the free ammonia con-
centration decreased (Figure 18).  Mixed liquor dissolved oxygen concen-
trations (Figure 19) did not significantly differ from those during the
period of lower oxygen transfer  (Figure 16).  One factor which may explain
the low DO levels is the additional nitrogenous oxygen demand (NOD) from
the residual ammonia in the system.  Combining the quantity of ammonia
produced from the degradation of organic nitrogen added during this period
with the reduction of the ammonia residual, it was calculated that 150
percent of the NOD was satisfied.

c_- Nitrogen removal at higher oxygen inputs - Nitrogen losses were
determined for two separate time periods at higher levels of oxygen
transfer in Ditch II.  The oxygen inputs were 815 and 790 gms 02 per
1000 bird-hrs. during the first and second balance periods:

During the first mass balance period at 815 gms 02 per 1000 bird-hrs.,
the loss of total nitrogen was less than that of organic nitrogen
(Table 22).  Accumulation of inorganic nitrogen in the system as ammonia,
nitrite, and nitrate was responsible for the difference.  Mixed liquor
concentrations of these compounds are presented in the segment of
Figure 15 denoted balance period (days 91 to 124).  Both NH4-N and N02-N
concentrations representing unsatisfied nitrogenous oxygen demand, in-
creased during the balance period.  Concurrently, mixed liquor dissolved
oxygen concentrations also increased (Figure 20).
                                    81

-------
       8.5
    I
    o.
       7.5
          110
                                  FREE   AMMONIA
                                         TOTAL  AMMONIA
120
130        140

 TIME,  days
150
Figure  18.  Mixed  liquor concentrations of total and free ammonia plus
           pH at  the oxygen  transfer capacity of 520 gms 02/1000 bird-hours
                                  82

-------
QO
00
                      2.0r—
                                    120
130        140

  TIME, days
150
160
                    Figure 19.  Dissolved oxygen concentrations in Ditch I  at the oxygen transfer
                               capacity of 520 gms CL/IOOO bird-hours

-------
     Z  oğ
     uj  £
     o
     <^   *ğ

     si

     o5
     UJ CC
     o ^
     crt U
     0)
       o
     Q O
       Z  2 ~
91
101
  Figure 20.
                                  Ill

                              TIME,  days
121
131
 Dissolved oxygen concentrations in  Ditch II at the  oxygen

 transfer capacity of 520 gms 02/1000 bird-hours
                       199
                     209

                  TIME, doys
                     219
           229
Figure 21.  Dissolved oxygen concentrations  in Ditch II at the 'oxygen

           transfer capacity of 790 gms 02/1000 bird-hours
                                84

-------
During the second mass balance period, 790 gms 02 per 1000 bird-hours,
removal of organic and total nitrogen was equal (Table 22).  No accumu-
lation of inorganic nitrogen occurred and concentrations of NH.-N, NO?-N,
and NO^-N remained near zero throughout the balance period.  Mixed liquor
dissolved oxygen concentrations are presented in Figure 21.

Liquid-Solids Separation -
A key aspect of the systems design approach used at Manorcrest was the
removal of residual solids in order to control mixed liquor total solids
(MLTS) concentrations.  The settling system did permit maintenance of
MLTS concentrations at levels below 25,000 mg/a and provided equilibrium
conditions to examine the relationship between SRT and treatment efficiency.
However, overall performance of the settling system was not satisfactory.
It was not possible to develop any clear relationship between overflow
rates and removal of solids due to variation in performance.

a_ - Gravitational settling - The poor settling performance was due in
part to the combination of liquid solids separation and sludge storage.
Gasification from denitrification and/or anaerobic processes resulted in
a floating layer of solids and pin floe.  Since the settling tank overflow
pipe was 0.6 m (2 ft.) below the liquid surface, the floating solids did
not present any problems with respect to clarification.  However, these
floating solids including feathers formed a mat which was extremely dif-
ficult to remove when the tanks were emptied.  The pin floes were carried
in the overflow reducing the solids removal efficiency.

Although these problems were significant, observations indicated that
the cause of the poor performance was more fundamental in nature, speci-
fically the liquid-solid separation characteristics of aerated poultry
wastes.  Comparison of settling efficiency at two different mixed liquor
total solids concentrations (MLTS) indicated the existence of a relation-
ship between total solids concentrations and settling characteristics.
                                    85

-------
 Comparisons of mixed  liquor and settling tank overflow total solids con-
 centrations at two different MLTS concentrations are presented in
 Figures  22 and 23.  In both instances, the settling tanks had been in
 operation for 3 days  prior to the first data point presented.  At MLTS
 concentrations below  12,000 mg/fc, the total solids concentrations in the
 settling tank overflow remained low over the first 20 days of operation
 (Figure  22).  In contrast at MLTS concentrations above 18,000 mg/£,
 settling tank overflow total solids concentrations increased rapidly
 (Figure  23).

 In  order to gain a clearer understanding of the settling characteristics
 of  aerated poultry wastes, the relationship of settling velocity to MLTS
 was examined over a wide range of MLTS concentrations.  This study was
 conducted at the AWML using aerated poultry wastes from the pilot plant
 scale  oxidation ditch located in that facility.

 The range of MLTS concentrations evaluated in the settling tests was
 3000 to  13,000 mg/£.  Both flocculent settling and zone settling were
 observed.  Flocculent settling occurred at MLTS concentrations below
 6,000  mg/£.  No attempt was made to quantify the flocculent settling
 characteristics of the wastewater.  At MLTS concentrations greater than
 6,000  mg/£, classical zone settling occurred with a distinct interface
 between  the clarified supernatant and the sludge.  A typical batch
 settling curve is presented in Figure 24.  The zone settling velocity
 (ZSV)  for each batch settling test was determined by calculating the
 slope  of the steepest portion of the curve as indicated in the Figure.
 The  combined results of the individual batch settling tests are presented
 in  Figure 25.  As shown, ZSV decreased dramatically at MLTS concentrations
 greater  than 11,000 mg/Ji.  These values were less than 1 cm/hr.  The
 data exhibited significant scatter.  Possible explanations for the
 scatter are wall  effects since a 1000 ml graduated cylinder was used
 for  the tests and the absence of stirring to break up bridged solids that
may  have occurred during settling.
                                    86

-------
                                         MIXED LIQUOR
                  SETTLING  TANK
                  OVERFLOW
                               61         66

                            TIME, days

Figure 22.   Comparison of mixed  liquor and settling tank overflow total
           solids concentrations at MLTS concentration below 12,000 mg/a
_ 22,000r-
                                 MIXED LIQUOR
                                  SETTLING TANK
                                  OVERFLOW
                              94        99

                            TIME, days

Figure 23.   Comparison of mixed liquor and settling tank overflow total
           solids concentrations at MLTS concentration above 18,000 mg/4
                               87

-------
00

00
             E
             o
                                             MIXED LIQUOR TOTAL SOLIDS

                                             CONCENTRATION, 9565 mg/l
                              10
20
     30        40

TIME, minutes
50
                 Figure 24.  Typical results from a batch settling test, aerated poultry wastes

-------
   160
w  140
.c
e
O
 •*

H


O
O
LJ
2

O
N
   120
   100
    80
z   60
_i
I-

ui   40|
en
    20
                 I
                           I
  1
                           I
      5,000     5,000
                         7,000
9,000
                         11,000

MIXED  LIQUOR  TOTAL SOLIDS

   CONCENTRATION, mg/l
13,000
 Figure 25-  Zone settling velocity versus total solids concentration

           in aerated poultry wastes
                             89

-------
 The  settling  data  collected also permitted the calculation of sludge
 volume indices  (SVI) at various MLTS concentrations.  Total solids
 were used  in  place of  total suspended solids in the calculation.  The
 lowest SVI's  were  observed between 6,000 and 11,000 mg/£ MLTS (Figure 26).
 The  results from both  the SVI and ZSV determinations indicated that the
 range for  optimum  gravitational liquid-solids separation of aerated
 poultry wastes  lies between 6,000 and 11,000 mg/£ MLTS.

 JD -  Screening and  centrifugation - Two mechanical liquid-solid separation
 devices were  examined  as alternatives to gravitational settling.  They
 were a basket type centrifuge and a vibrating screen.  Since both items
 were obtained on a loan basis from the respective manufacturers, the
 extent of  these tests  was limited.

 The  centrifuge  tested  was a DeLaval 30.5 cm (12 in.) basket type unit.
 The  unit was  operated  2750 rpm and the flow rate was 3.8 £ per minute
 (1 gal.  per minute).   The test results are presented in Table 24.

                Table  24.  RESULTS OF CENTRIFUGE TEST



Total solids
Volatile solids
Influent,
mg/£
14,150
9,078
Effluent,
nig/*
3,530
1,652
%
Removal
75.0
81.8
Under flow
solids, %
15.8
11.7
The underflow solids were semi-solid, and it appeared that they could  be
handled with solid manure handling equipment.

The vibrating screen tested was a 46 cm  (18 in.) Sweco Vibro-Energy
Separator that can be operated in a single or multiple stage mode with
screens placed in series.  The vibrational motion of this unit is derived
                                    90

-------
   100


    90


    80
x
LJ
O
LJ
O
O
D
_l
V)
    70
    60
LJ   __
5   50


O   40
    30
    20
     3000     5000     7000     9000     11000    13000

               TOTAL  SOLIDS  CONCENTRATION, mg/I
    Figure 26.  Sludge volume Index versus total solids concentration
              in aerated poultry wastes
                             91

-------
 from the  interaction of suspension springs and rotating weights.
 Figure  27 is  a  vertical section of the unit.

 Three different mesh size screens; 200, 250, and 325 were evaluated.
 In addition  to  the  screen size, the Sweco unit has two other operating
 variables.   One is  the number of additional weight plates attached to
 the lower motor weight.  This controls the vertical movement of the
 material  as  it  travels horizontally across the screen cloth.  The manu-
 facturer  recommends several plates for heavy, coarse, or wet material.
 The maximum  number, four, were used throughout this study.  The second
 variable  is  the degree of lead of the bottom with respect to the top
 motor weight, i.e., the lead angle.  This controls the horizontal
 pattern of travel across the screen.  Examples of average material travel
 patterns  are  presented in Figure 28.

 The initial  phase of this study investigated the relationship of lead
 angle to  performance for a constant screen size, 200 mesh.  The test
 results are  presented in Table 25.  At the higher lead angles, 45°
 and 60°,  flow was restricted to a maximum of 6.7 a per minute.  When
 flow was  increased  beyond this amount, the rate of solids loading to
 the screen was  greater than the rate of solids discharge.  The result
 was an  accumulation of solids which blocked the flow of filtrate through
 the screen.   Therefore, a major portion of the flow was short circuited
 through the solids  discharge spout (Figure 27).  As the lead angle was
 decreased, maximum  permisible flow rate increased.  At all lead angles,
 the total solids content of the cake decreased with increasing flow
 rates.  Subsequent  tests were conducted at a constant lead angle of 0°
 and  flow  rate of 13.3 £ (3.5 gal.) per minute.

 The objectives of these subsequent tests were to examine the relationships
of  total  suspended solids (TSS) concentrations to performance and the
effect of screen size on TSS removal.  Performance was evaluated  in terms
of TSS removal and the dry matter content of the separated solids.  The
results  of these tests are presented in Table 26.  Single stage  screening
                                    92

-------
                                         FEED

                                         BUCKET  TYPE
                                         VELOCITY REDUCER
   INTERCHANGEABLE
   SIEVE -
LIQUID DISCHARGE
     SPOUT-
                                            SOLIDS
                                            DISCHARGE
                                            SPOUT
 Figure 27.
Vertical  section  through a basic single deck,  18 inch
Sweco Vibrating Screen Separator
      0° Lead-average material
      may be thrown straight
      and may give insufficient
      separation
     40° Lead-may give average
     dry material maximum
     efficient screening  pattern
  Maximum lead  may  keep oversize
  material  from being  discharged
  and assist in receiving maximum
  thruput of minus  material which
  tends  to "ball"
                     15° Lead-average material
                     may begin to spiral
                     60° Lead-may give average
                     wet material maximum
                     effecient screening pattern
                                               DISCHARGE
                                               SPOUT

                                               ROPE OF
                                               MATERIAL
                                               SCREEN SURFACE
                      Roping pattern on the screen
 Figure 28.   Illustration of average material travel on the screen
                                 93

-------
Table 25.  RELATIONSHIP BETWEEN LEAD ANGLE AND PERFORMANCE
           200 MESH SCREEN, 0.074 mm
Average Lead Flow Rate,
Influent Angle Ji/min.
Total Suspended
Solids Concentration,
1970 60° 2.5
4.0
6.7
45° 2.5
4.0
6.7
2800 30° 5.7
13.3
4890 15° 2.0
13.3
0° 4.0
8.0
13.3
Percent Removal
Total Suspended
Solids
23.5
24.8
17.6
29.3
34.0
22.1
37.1
36.2
34.8
34.5
27.4
22.9
24.8
Cake
Percent Total
Solids
11.9
10.6
9.0
11.7
10.7
9.0
13.3
10.7
12.2
11.4
13.2
11.5
11.1

-------
Table 26.  RESULTS OF SINGLE AND TWO STAGE SCREENING TRIALS
Feed Solids
Concentration, mg/£ .
Screen
Mesh No.
1 Stage
200
Size, Total
mm. Solids
0.074 4,512
5,228
9,575
23,625
2 Stage
200
plus
250
200
plus
325
0.074 9,:
0.062
0.074
0.044
525

Total
Suspended
Solids
1,974
2,425
5,015
17,676
4,763

Total
Suspended
Solids, mg/&
1,302
1,811
3,865
13,364
3,748
3,678
3,758
3,249
Filtrate
% Removal of
Total Suspended
Solids
34.0
35.4
22.9
24.8
21.3
22.8
21.1
31.8
Cake
Dry Matter
Content
Percent
10.6
10.2
11.5
11.1
15.4
11.0
15.4
2.7

-------
 trials  were  conducted with  200, 250, and 325 mesh screens over a range
 of TSS  from  1,302  to 13,364 mg/fc.  Performance of the 250 and 325 mesh
 screens individually were unsatisfactory since the flow was limited to
 low rates  with  these screens.  The results from the single stage trials
 (Table  26) indicate that removal of TSS decreased as influent TS and TSS
 concentrations  increased.   The separated solids consisted of coarse
 materials  such  as  seed  coats, feed, and feather parts.  The cake was
 semi-solid similar to wet sawdust and appeared amenable to handling as
 a  solid.

 Two stage  screening tests were conducted using combinations of 200 plus
 250 and 200  plus 325 mesh screens in series.  The addition of the 250
 mesh screen  only nominally  increased TSS removal (Table 26).  Although
 the dry matter  content  of the cake from the 250 mesh screen, 11.0 percent
 was similar  to  that of  the  separated solids from the single stage 200
 mesh tests,  the physical appearance differed.  The 325 mesh screen in-
 creased TSS  removal by  11.2 percent over the first stage 200 mesh screen
 with a  total  TSS removal of 31.8 percent.

 PROBLEMS IDENTIFIED
 Introduction
 One of  the objectives of this study was to identify problem areas in
 the design and  operation of aeration systems for poultry wastes.  During
 the course of the  investigation, several problems were encountered.
 They  include  equipment  breakdowns, sedimentation of solids in both ditches,
 foaming, feathers, and  excess  water leakage from the bird watering system.
 The first  two items placed  constraints on the evaluation of the system
 performance.

 Equipment  Problems
The major  equipment problem involved the Thrive Centers cage rotor in
Ditch II.  The most frequent problem was failure of connection 1 to 2
between the paddle bar and wheel plate assembly (Figure 29).
                                     96

-------
                                                                       BEARING
SO
WHEEL PLATE
ASSEM
                                                      CONNECTING
                                                      BRACKETS
                                                                         BOLT

                                                                PADDLE  BAR
                          Figure 29.  Assembly diagram of a Thrive Center Cage Rotor

-------
 Two  types of failure occurred.  They involved shearing of the connecting
 brackets, which were flat plates butt welded to the wheel plate assembly,
 and  failure of the connecting bolt.  The initial type of failure was shear-
 ing  of  the connecting brackets.

 Following the third failure of this type, it was concluded that the bracket
 shear problem was not an isolated problem but involved inadequate design.
 Upon informing Thrive Centers, Inc. of the difficulties, they replaced both
 wheel plate assemblies.  On the new units, the flat plate bracket was re-
 placed  by an angle iron bracket.  At this point, shearing of the brackets
 was  replaced by failure of the connecting bolts.  The cause of the bolt
 failures is not clear.  However, it may be related to over tightening of
 certain bolts during reassembly following replacement of the wheel plates.

 The  problem of bracket shearing was due to a design change by Thrive which
 has  been rectified.  Bolt failure appears to be isolated to the Manorcrest
 unit.   Discussion with other owners of the Thrive rotors indicates that
 this is not a common problem.  However, these and other problems such
 as drive belt breakage caused aeration to be interrupted for periods
 exceeding 24 hours, on eight separate occasions during the 19 months of
 system  monitoring.

 The  bearings of both aerators were replaced due to deterioration following
 the first eight months of operation.  During this period, lubrication was
 performed weekly.  A daily lubrication schedule was instituted following
 bearing replacement.  No further problems were encountered in the remainder
 of the study period.

Sediment Accumulations
The accumulation of a significant quantity of solids in the bottom of
both oxidation ditches was a major problem in this study.  As the accumu-
lation  of sediments increased, the velocity of the mixed liquor decreased
                                     98

-------
to the point of a complete stoppage of circulation.  This occurred
several times in Ditch II requiring the complete removal of the ditch
contents.  Conversely, circulation in Ditch I was always maintained
although velocity did decrease with sediment accumulation.

Sediment accumulations were first measured in April 1974, when Ditch II
velocities were approaching zero.  At this time, Ditch II had been in
operation for 8 months.  A profile of the measured sediments is presented
in Figure 30.  Based upon the sediment measurements, it was calculated
that 30 percent of the ditch liquid volume was occupied by settled
solids.  At this time, it was necessary to empty the ditch to facilitate
the replacement of the Thrive rotor wheel assemblies.   At this time,
accumulated sediments were removed.  This permitted reestablishment of
ditch circulation through the end of the laying cycle, August 1974.

Sediment accumulation was measured in Ditch I after 10.5 months of opera-
tion.  The sediment profile is presented in Figure 31.  The volume of
accumulated solids was 22 percent of the liquid volume.  This indicates
that Ditch I had a lower rate of solids deposition since the accumulated
quantity was less than that in Ditch II and period of operation was
longer.

Prior to the beginning of the second year of operation, the accumulated
sediments in both ditches were completely removed.  The liquid depth was
reduced from 50.8 cm (20 in.) to 33 cm (13 in.).  The objective was to
reduce the cross-sectional area of the liquid.  It was assumed that with
a constant aerator depth and therefore pumping capacity, the result would
be a substantial increase in mixed liquor velocity, since the cross-sec-
tional liquid area was reduced by 35 percent.  This reduced the mixed
liquor volume from 105,980 £ (28,000 gal.) to 68,887 a  (18,200 gal.).
Initial velocities under these conditions were 0.36 m/sec (1.2 ft/sec)
and 0.43 m/sec (1.4 ft/sec) for Ditches I and II.  A comparison of
initial velocities for years I and II are presented in Table 27.
                                    99

-------
o
o
     -  io
                                                              FLOW
                   40
40
80
 240
             120       160       200
                 DITCH  LENGTH, ft.
Figure 30.  Sediment profile in Oxidation Ditch  II, 1973-74


                                   FLOW
280
                                                                      320
                             80
          120       160       200
              DITCH LENGTH, ft.
240
                                                     280
          320
                          Figure 31.  Sediment profile in Oxidation Ditch I, 1973-74

-------
         Table 27.   COMPARISON OF INITIAL DITCH VELOCITIES AT
                    VOLUMES OF 68,887 £ AND 105,980 £
                        Year I (105,980 £)        Year II (68,887 a)
Ditch I
Ditch II
0.26 m/sec.
0.38 m/sec.
0.36 m/sec.
0.43 m/sec.
The problem of sediment accumulation and reduced mix liquor velocity
reoccurred under the new operating conditions.   Figures 32 and 33 show
the profiles of the settled solids at two points in time in each ditch.
The profiles indicate a pattern of initial solids accumulation immediately
downstream  from the aeration unit followed by deposition further down-
stream.  It was necessary to again remove the sediments from Ditch II
after 5 months of operation since the mixed liquor circulation had
ceased at that time.

Composite samples of the accumulated solids were taken from each ditch
when the last sediment measurements were made.   The samples were analyzed
to characterize their composition.  The results of the analyses and
comparison to raw manure are given in Table 28.

                  Table 28.  SEDIMENT CHARACTERISTICS


% TS
y VS
7° TS
mg COD
mg FS
Ditch I
30.3
30.6
729
Ditch II
19.4
49.0
1760
Raw Manure,
1974-1975
--
72
2544
                                   101

-------
                                      FLOW
o
tc
                                                       AFTER  2MONTHS  of OPERATION
                                                       AFTER  4MONTHS  of OPERATION
     Q.
     LJ
     Q
LU
S
Q
Ixl
CO
                                    120       160       200
                                  DITCH  LENGTH, ft.

                 Figure 32.  Sediment profile in Oxidation Ditch I, 1974-75
                   240
                                        280   320
                                       FLOW
• AFTER 2 MONTHS of OPERATION
A AFTER 4 MONTHS of OPERATION
120       160       200
DITCH  LENGTH,  ft.
                                                                     240
                                                                           280
                                     320
                        Figure  33.  Sediment profile in Oxidation Ditch II, 1974-75

-------
The differences in the sediment characteristics of the two ditches
appear to be related to mixed liquor velocities prior to sampling.  The
velocity of Ditch II was approaching zero at the time of sampling.  Raw
manure was accumulating on top of the initial sediment layer and was
included in the sample.  This could account for the higher percentage
of volatile solids and the larger COD to fixed solids ratio.  The
analytical results indicate that sediment in Ditch I consisted primarily
of inorganic material.

Foaming, Feathers, and Excess Mater
Foaming problems were encountered during this study.  However, these
problems were of a nuisance rather than a serious nature.  No endanger-
ment of the animals or workers in the building ever occurred.  Excessive
foaming occurred in Ditch II but not in Ditch I.  Therefore, inadequate
oxygen supply was discounted as the cause of foaming.  Ditch I was a
minimally aerated system.

The cause of the foaming problem appeared to be related to the movement
of the foam around the ditch.  Foam was usually present on this surface
of Ditch I in a thin layer or in patches.  However, surface velocity
was always adequate to maintain continuous movement.  Therefore, a
constant cycle of foam generation and breakdown by the aerator occurred.

The foaming problems encountered in Ditch II appeared to be related to
the interruption of this cycle due to a stoppage in the movement of the
foam layer.  The principle factor responsible for cessation of foam
layer movement was reduction in mixed liquor velocity due to sediment
accumulation.  Because of minimal friction between the foam layer and
the mixed liquor surface, the ditch sidewalls were adequate to stop
foam movement as mixed liquor velocities decreased.  Therefore, the
cycle of foam generation and breakdown was interrupted.  Generation of
foam continued with the resulting accumulation causing an overflow
onto the service aisles on several occasions.  Used motor oil was added
                                   103

-------
 to  Ditch  II  to  control foam during the first year.  When the liquid
 depth  was  decreased  to 33 cm  (13 in.) at the beginning of the second
 year,  freeboard increased to  41 cm (16 in.).  This was adequate to
 contain  the  foam,  and oil additions were not necessary.

 The role  of  the accumulated sediments to the foaming problem is unclear.
 Both ditches had significant  accumulations of these sediments, but
 foaming  problems only occurred  in Ditch II.

 Feathers  were another problem.  Initially, the feathers were allowed to
 move through the overflow standpipes into the settling tanks.  However,
 they accumulated in  the first settling tank and formed a floating mat.
 On  several occasions, this mat  blocked flow through the standpipes.
 When the  settling  tanks were  emptied, it was necessary to remove the
 feathers  manually  using rakes and shovels.

 To  eliminate the reoccurrence of this problem, baffles were installed
 around the standpipes to exclude the feathers from the settling tanks.
 This was  possible  since most  of the feathers were on the surface.
 However,  this resulted in the accumulation of large mats of floating
 feathers which  would be stopped by obstructions such as the overflow
 standpipes or the  propeller housing in Ditch I prior to its removal.
 It  was necessary to remove these mats with a rake.  This was done in
 response  to  accumulation which  varied from daily to weekly depending
 on  the rate  of  feather loss.

 Excessive leakage  from the bird watering system was greater than
 evaporative  losses.  This caused a small overflow from the settling
 tanks  onto the  corn fields behind Building No. 1.  The frequency and
 quantity varied  due to variation in amount of leakage and changes in
 evaporative  conditions.  The watering system consisted of individual
watering units  known as Hart  Cups.  Figure 34 is a schematic drawing  of
a Hart Cup.  Operation of the on-off valve, which consisted of a rubber
                                  104'

-------
                                  RUBBER
                                    SEAL.
                                        A
                               VALVE  SEAT
Figure 34.  Cross section of a Hart Cup
                  105

-------
 seal and seat, is dependent on water pressure.  Variations in water
 pressure caused the units to overflow.  Since dilution water was
 necessary to  liquify the manure with the previous management system,
 leakage was desirable.  Therefore, no pressure regulators had been
 used.  Following recognition of the problem, pressure regulators were
 installed.  This reduced but did not completely eliminate the problem.

 Overflow of the Hart Cups also occurred when particles, primarily feed,
 lodged between the rubber seal and seat.  This held the valve open
 causing a drop in water pressure in the line.  Then other cups would
 overflow due  to the drop in water pressure.  Although the cups were
 checked daily and repaired when necessary, this was not adequate to
 control the excess leakage.

 CAPITAL AND OPERATING COSTS
 One of the study objectives was the evaluation of the economic impact
 of utilizing aeration systems for poultry wastes.  In keeping with this
 objective, the major capital and operating costs were determined.
 Capital and operating costs were not constant due to differences in
 aeration equipment and methods of operation.  Each situation was examined
 individually.

 The capital costs for the two oxidation ditches included costs for the
 modification of the existing pits, settling and storage tanks, and
 aeration equipment.  The modification costs were the labor and materials
 for the conversion of the existing manure collection pits into two
 oxidation ditch channels and the equipment installation including
 necessary electrical  modifications.  Settling tank costs included labor
 for excavation, tank placement, and backfilling.  The cost of the industrial
propeller originally used in Ditch I was excluded since it was found  to
be ineffective and was removed from the system.
                                    106

-------
Table 29 contains the initial cost, estimated useful life, and annual
cost for each capital item.  These figures were used to determine the
total and annual capital costs for each oxidation ditch which are
presented in Table 30.  Construction costs were equal for each ditch.
The difference in aerator costs is responsible for the overall differences
between the two ditches.

The operating costs examined included power, maintenance and repairs,
and taxes and insurance.  Power costs varied with the level of oxygen
transfer and each situation was examined independently.  The numerous
mechanical problems encountered in this study made estimation of
maintenance and repair costs extremely difficult.  The number of
mechanical problems encountered in this study do not appear to be
representative.  Therefore, maintenance and repair costs were estimated
at 2 percent of the total initial investment for each ditch.  This appears
reasonable since daily maintenance was minimal consisting only of bear-
ing lubrication which was done during feeding or egg collection.  Yearly
bearing replacement has been shown to be the major repair item in other
experiences with similar systems.  Taxes and insurance were estimated
to be 3 1/2 percent of the annual capital cost.

Energy costs at the three different levels of oxygen transfer examined
in this study are presented in Table 31.  A summary of the overall
operating costs are presented in Table 32.  As shown, energy is the
major operating cost, comprising 60 to 73 percent of total operating
costs.  Differences in maintenance and repair costs and insurance and
taxes betweeen the two ditches were small.  Problems in the area of
liquid-solids separation precluded a realistic assessment of ultimate
disposal costs.

Table 33 contains a total .cost summary for aeration of poultry wastes
at Manorcrest Farms.  As shown, aeration systems are capital intensive   .
with capital costs responsible for 58 to 66 percent of total costs
depending on level of oxygen transfer and therefore energy consumption.
                                   107

-------
   Table 29.  INITIAL AND ANNUAL CAPITAL COSTS - MANORCREST PROJECT

              AERATION SYSTEMS COMPONENTS

Total Cost* Estimated Annual Cost**
Useful Life
Years
Construction
Oxidation Ditches
Settling Tanks
Equipment
Thrive Center
Cage Rotor
Montair Brush
Aerator

8,735 20 958
3,040 20 333

2,120 10 346

1,500 10 244
*  1973 prices

** Amortized at 9 percent per year over  the  estimated  useful  life,  no
   salvage value
                                 108

-------
           Table  30.   TOTAL AND ANNUAL  CAPITAL  COSTS  FOR  THE
                      MANORCREST AERATION  SYSTEMS
                   Item                    Ditch  I       Ditch  II

      Capital  Costs
          Total                             $ 7,388       $8,008
          Per 1,000 hens                     1,847        2,002
          Annual  cost per year                 890          992
          Annual  cost/1,000 hens/year          222          248
          Cost per dozen eggs*               .0111        .0124


*Assumes 4,000 hens per ditch and 20 dozen eggs per hen/yr.
                                  109

-------
                         Table  31.   ENERGY COSTS* FOR AERATION IN RELATION TO
                                    THE  LEVEL OF OXYGEN TRANSFER

Level of Oxygen
Transfer Capacity,
gms 02/1000 bird-hrs.
351
520
790 &
815
Ditch Aeration Unit kwhr/ Cost/ Cost/**
No. 1000 hens/yr 1000 hens/yr Dozen Eggs
i
I Brush Aerator 3,328 $ 66.89 $.0033
I Brush Aerator 4,558 91.62 .0046
II Cage Rotor 6,524 131.14 .0067
* Energy cost of $.0201 per  kilowatt-hour
**Assumes 4,000 hens per ditch and  20 dozen eggs per hen-year

-------
     Table  32.  OPERATING  COSTS  FOK  MANORCREST AERATION SYSTEMS
               PER  1,000  HENS PER YEAR




Energy Costs
Maintenance and Repairs
Taxes and Insurance
Total
Cost per Dozen* Eggs
Ditch I
Oxygen Transfer
351
66.89
36.94
7.78
111.61
.0056

Capacity,
520
91.62
36.94
7.78
136.34
.0068
Ditch II
Gms 02/1000 bird-hrs.
790 & 815
131.14
40.04
8.68
179.86
.0090
*Assumes 20 dozen eggs per hen-year
                                    111

-------
            Table 33.  COST SUMMARY OF AERATION OF POULTRY
                       WASTES, MANORCREST FARMS



Ditch I
Oxygen Transfer Capacity, Gms
Costs/1,000 hens/year
Annual capital
Operating
Total
Costs/dozen eggs*
Annual capital
Operating
Total
351
$ 222
112
$ 334

$.0111
.0056
$.0167
520
$ 222
136
$ 358

$.0111
.0068
$.0179
Ditch II
02/1,000 Bird-hrs.
790 & 815
$ 248
180
$ 428

$.0124
.0090
$-0214
*Assumes 20 dozen eggs per hen-year
                                   112

-------
                             SECTION VII
                  DISCUSSION OF EXPERIMENTAL RESULTS
GENERAL
The primary objective of this investigation was to demonstrate and
evaluate the potential of aerobic treatment to reduce the air and water
pollution potential of poultry wastes when employed under commercial
conditions.  The concepts used in the design and operation of the Manor-
crest aeration systems were derived from the results of smaller scale
studies.  Although the specific goals of odor control, waste stabiliza-
tion and nitrogen management were achieved, overall system performance
was not as perfect as desired.  The problems encountered were primarily
related to the physical system design.  This identified a shortcoming
in the design approach which was process oriented.

The problems of sediment accumulation and poor liquid solids separation
as well as equipment failures hindered but did not eliminate the demon-
stration of the process design parameters for aeration systems for
poultry wastes..

This section will discuss the results in terms of the process design
concepts employed as well as the physical problems encountered and their
role in overall systems design.  Also included is an evaluation of the
economic impact of utilizing aeration systems for waste management in
egg production.

ODOR CONTROL
An objective of this study was to demonstrate the odor control capabilities
of the aeration process.  Malodors emanating from ventilation systems
and wastes spread on the land have been a major point of conflict between
egg producers and other rural residents.  Elimination of odor problems
was demonstrated in this study.

                                    113

-------
 The additional benefit of improved environmental conditions within the
 building should also be recognized.  The elimination of malodors, flies,
 and other vermin greatly improved the working conditions for the people
 caring for the birds.  This point was frequently cited in discussions
 about the study with Manorcrest employees.  Similar observations were
 made by members of the Cornell Agricultural Waste Management Program
 who had visited the site prior to conversion to the aeration systems.
 The high rise house, Building No. 2, provided some basis for comparisons.
 Although environmental conditions in that building were superior to the
 anaerobic liquid manure system previously in Building 1, they were not
 as good as the conditions in Building No. 1 with aeration.  Both employees
 and visitors to the demonstration site commented on this fact.   The
 additional benefit of improved working conditions appears to be signi-
 ficant in that poor working conditions due to odors, etc., are often
 identified as a major problem area in attracting good farm labor.

 DESIGN PARAMETERS
 The relationship between oxygen transfer and mixed liquor total solids
 (MLTS) concentration formed the basis for the Manorcrest aeration systems
 design.  The objective was to maximize oxygen transfer by restricting
 the MLTS concentration to a maximum of 20,000 mg/£.  This would maintain
a values at or approaching unity.  This required removal of residual
solids and the use of SRT as a design and operational parameter.

Although the design SRT was based on maintenance of nitrifying conditions,
relationships between the degree of stabilization and SRT in aerobically
treated poultry wastes had been previously developed (11,16).  Variations
in SRT due to inconsistent solids removal permitted confirmation of the
earlier observations.  The results from this study have been presented
in Figure 12 through 13.  These results were combined with results obtained
in a  previous study and are presented in Figures 35 through 38.
                                    114

-------


_J
o
LJ
or
0s-
50
40

30
20
10
0
A
•^^^'*
A^>-— 	 A*" * A

• THIS STUDY
_ A MARTIN et al (16)
1 1






0 10 20 30 40

F

O
LJ
or


SRT, days
igun
70
60
50
40
30
20
10
C
2 35. Observed relationship between SRT and removal
of total solids in aerated poultry wastes
A
O^M^
	 * • ^^^^
•"A A
A
• THIS STUDY
A MARTIN et al ( 16)
^mmmm
1 1






) 10 20 30 40
                      SRT, days


Figure 36.   Observed relationship between  SRT and removal
            of  volatile solids in aerated  poultry wastes
                         115

-------
    60


    50


§
O 40
UJ
cc
    30
    20
    10
                           • THIS STUDY
                           * MARTIN  etal (16)
              10        20        30
                    SRT, days
                                                40
 Figure 37.  Observed relationship between SRT and removal
            of COD in aerated poultry wastes
    80
   70
5  60
£ 50
40 —


30 —
              10
                              THIS STUDY
                              MARTIN  et ol (16)
                            1
    20
SRT, days
30
                                                40
Figure 38.  Observed  relationship between SRT and removal
           of organic nitrogen  in aerated poultry wastes
                         116

-------
There is good agreement between the results of these separate studies.
These data serve to define the relationship between removals of total
solids, volatile solids, COD, and organic nitrogen and SRT and show
that removal increases with SRT.  Therefore, regulation of SRT provides
a mechanism for control of the degree of stabilization to meet specific
objectives.  With proper design, it should be possible to limit oxygen
requirements necessary to meet exerted carbonaceous oxygen demand and
provide odor control.  Oxygen requirements for nitrogenous oxygen demand,
if nitrification or nitrification-denitrification are part of the overall
stabilization objectives,also could be developed using a similar approach.

Oxygen supply was always greater than the exerted carbonaceous oxygen
demand in this study (Table 19).  No odor problems were encountered
even at the lowest level of oxygen transfer, 350 gm 02/1,000 bird-hours.
However, the rate of oxygen transfer exceeded the rate of COD removal
by 25 percent.  Satisfactory odor control has been reported when the
estimated rate of oxygen transfer exceeded COD removed by only 2
percent (16).  That study also involved the evaluation of aeration of
poultry wastes under commercial conditions.  Based upon the combined
results presented in Figure 37, reduction of SRT from 36.5 to 30 days
should reduce oxygen requirements, expressed as COD removed for odor
control,  by about 19 percent.  As shown in Figure 38, the exerted nitroge-
nous  oxygen  demand from ammonification of organic nitrogen will also
decrease with decreases in SRT.

Due to the interrelationships between SRT and waste stabilization as
well as those between SRT and nitrification, it is not possible to
specify a single SRT for all aeration systems.  Individual situations
and waste management objectives must be considered.  However, the
results of this study (Table 21) and those of a previous study (11)
show that most of the soluble COD is removed at an SRT of 10 days.
Therefore, a minimum SRT of 10 days should significantly reduce the water
pollution potential  from soluble carbonaceous compounds.  These compounds
                                   117

-------
 have  the greatest potential for contamination of surface waters via
 overland flow.  Increased removal of total solids, volatile solids,
 and COD can be achieved by increasing SRT beyond 10 days (Figures 35
 through 37).  Increase in SRT beyond 10 days will increase oxygen
 requirements but will also provide a greater degree of waste stabilization.
 This  may be necessary if storage occurs following aerobic treatment and
 odorous end products from anaerobic processes can result from remaining
 unstabilized wastes.  It was not possible to determine a clear relation-
 ship  between ma!odors generated from the stored sludge and the degree of
 stabilization in this study.  It was observed that the nature of the
 odors generated during storage differed from those common to untreated,
 liquid poultry manure.  The intensity of the malodors from the stored
 sludge was significantly lower and diffused rapidly.  In contrast,
 untreated liquid poultry manure continues to be a source of odors for
 an extended period of time following field spreading.  This comparison
 shows that aeration is effective in controlling odors following field
 spreading even if storage follows aeration.

 If nitrification is desired, provision of an adequate SRT to maintain a
 nitrifying population will be the constraining factor in determining
 the minimum SRT.  The increased SRT for nitrification, particularly at
 low temperature, will increase oxygen requirements to meet both the addi-
 tional exerted carbonaceous oxygen demand and the nitrogenous demand.
 The end result will be an increased degree of stabilization as well as
 nitrification.

 NITROGEN
 The decision to remove or conserve nitrogen from poultry wastes is
directly related to the opportunities to recycle this element through
crop production.  Although animal production not accompanied by cropping
activities has the most stringent nitrogen removal requirements,  the
Manorcrest system design identified the need for nitrogen removal when
crop production is limited.
                                   118

-------
The potential for nitrogen removal is limited by the ammonification
process which is a function of SRT (Figures 13 and 38).  The degree of
nitrogen removal via ammonia stripping in oxidation ditches was shown
to be substantial when nitrification was inhibited by the lack of available
oxygen.  Therefore, it appears that inhibition of nitrification is not
an effective method of nitrogen conservation in aeration systems for
poultry wastes.  In addition, the disadvantages of the odor of ammonia
in the building in the case of an in-house oxidation ditch and the potential
adverse environmental impact from the discharge of ammonia into the
atmosphere should be recognized.

It is necessary to meet the total exerted carbonaceous and nitrogenous
oxygen demand to achieve nitrification.  Based upon the mass balance
results, it was calculated that the total exerted oxygen demand was
514 gms 02/1000 bird-hours.  Oxygen transferred was 520 gms 0^/1000
bird-hours.  This demonstrates the validity of the method used to cal-
culate oxygen demand, Equation 8.  Since the oxygen supply was equal to
the demand, no residual dissolved oxygen should have been present in the
mixed liquor.  As shown in Figure 19, residual dissolved oxygen concen-
trations were minimal during this period.

The potential for nitrogen conservation by maintenance of an adequate
residual dissolved oxygen concentration could not be evaluated due to
opportunities for denitrification in the settling tanks.  At the highest
levels of oxygen transfer, oxygen transfer capacity was 142 and 153
percent of the total exerted demand based on calculations from the mass
balance results.  This indicated that residual dissolved oxygen concen-
trations should have been maintained.  Dissolved oxygen measurements,
(Figures 20 and 21) confirm this conclusion.  However, results of pilot
plant studies (20) have shown that a 30 percent loss of nitrogen via denitri-
fication can occur even at high dissolved oxygen levels.  It is necessary to
examine the value of the nitrogen conserved in comparison to the additional
equipment and energy costs to determine the feasibility of this approach.
                                     119

-------
 The observed  removal of nitrogen via nitrification-denitrification
 even at relatively  long SRT's  (Table 22) demonstrated that the addition
 of an organic carbon source such as methanol is unnecessary for deni-
 trification with  these wastes.  In comparison, the addition of an organic
 carbon source is  commonly required for denitrification of nitrified
 domestic and  industrial wastes.
                                                              t v

 The observation of  NO^-N on the 14th day of operation of Ditch II, demon-
 strated that  seeding is not necessary to introduce nitrifying organisms
 into these systems.  However,  nitrification patterns indicating inhibi-
 tion were observed  on several  occasions (Figures 14 and 15).  Un-ionized
 ammonia (NH-) and un-ionized nitrous acid (HN02) could have been the
 inhibitory compounds.  Inhibition of nitrification by these compounds
 in poultry and other wastewaters has been reported (55).  Free ammonia
 concentrations from 0.1 to 150 mg/£ were noted to be inhibitory.   Free
 ammonia inhibition  to Nitrobacter occurred at concentrations lower than
 those that inhibited Nitrosomonas.  The inhibitory range for free nitrous
 acid was  0.2  to 2.8 mg/£.

 During  the first  14 days of operation, the free ammonia concentration
 reached a maximum of 21.3 mg/£.  This is well within the above inhibitory
 range.   Complete  inhibition did not occur.  However, comparison of NO~-N
 and  NO--N concentrations indicates that the inhibition to Nitrobacter
 was  greater than  that to Nitrosomonas.  With the accumulation of nitrite,
 free  nitrous  acid levels increased and reached a maximum of 2.2 mg/£ on
 day  42  which  is also well within the suggested inhibitory range.

 The accumulation of NO^-N affected system performance in several  ways.
 First,  complete nitrification  did not occur.  Significant mixed liquor
ammonia residuals remained (Figures 14 and 15).  It was observed that
residual dissolved oxygen levels increased with increased NCL-N concen-
trations  (Figure 20).  This indicates a reduction in exerted oxygen demand
as N0~N concentrations increased.
                                   120

-------
The results of this study demonstrates that it is not necessary to seed
these systems in order to introduce nitrifying organisms.  However, it
may be desirable to prevent an initial ammonia accumulation and the
resulting free ammonia inhibition.  This would, in turn, prevent the
free nitrous acid inhibition from developing.

LIQUID-SOLIDS SEPARATION
The process design concepts of a controlled mixed liquor total solids
concentration and SRT are dependent on the removal of residual solids.
Continuous dilution does not appear practical and an effective mechanism
for liquid-solid separation is required.  This study examined three alter-
native approaches; gravitational settling, screening, and centrifugation.

Gravitational Settling
It does not appear that the poor performance of the gravitational  liquid
solids separation system at Manorcrest is a true indicator of the potential
of this approach.  The zone settling velocity studies suggest that at
MLTS concentrations below 11,000 mg/£, aerated poultry wastes have good
settling characteristics.  Therefore, this approach should not be entirely
discounted.  However, it is clear that the clarification and storage
functions should be separated to prevent solids flotation in the clarifi-
cation unit due to gas production from denitrification and other anaerobic
processes.

In order to access feasibility in terms of clarifier size requirements,
preliminary surface area requirements based on the ZSV test were calcu-
lated.   The design approach presented by Lawrence (56) which is based
upon the batch flux method (57) was used.  The clarifier surface area
                                         2      2
requirements were calculated to be 929 cm  (1 ft ) per 1000 birds.  The
design  conditions were as follows:
         Mixed liquor total solids concentration - 8,000 mg/Ji
         Solids retention time                   - 15 days
         Underflow solids concentration          - 70,000 mg/Ğ.
         Flow through the clarifier              - 2440 A/day

                                   121

-------
 This  indicates that a large clarification unit would not be required and
 that  surface area was not an independent limiting factor in the Manorcrest
 settling units.

 Using the specified design conditions, sludge production was calculated
 to  be 287 a per 1000 birds per day (76gal./1000 birds/day).  The volume
 of  sludge requiring ultimate disposal would be 104 a per bird per year
 (28gal./bird/yr).  Assuming the use of a 9462 £ (2500gal.) manure spreader
 and an estimated time requirement of 30 minutes per load for loading,
 transportation, and spreading, the estimated time required to dispose of
 the yearly sludge production from 1000 birds would be 5.5 hours per year.

 Caution should be used in utilizing the zone settling velocity results
 reported here as a basis for design.  Further investigation is warranted
 to  confirm these preliminary results and evaluate the effects of variation
 in methods of treatment system operation before using the reported data
 for actual design.

 Screening and Centrifugation
 The results of the screening tests indicate that this process has only
 limited potential for liquid-solids separation in aerated poultry wastes.
 The major problem is that the mixed liquor suspended solids are very
 small.  The results of the 200 mesh screening test indicated that 60 to
 80 percent of the suspended solids were less than 0.074 mm in diameter.
 Based upon sieve analyses of fresh poultry wastes, 49 percent of the manure
 solids were reported (58) to be finer than 0.074 mm.  Therefore, it appears
 that aerobic treatment changes the particle size distribution in these
wastes.  This fact is important not only with respect to screening but
also to gravitational settling and possibly other separation processes.

A possible application of screening would be as the first step before
aeration where it would be desirable to handle coarse solids separately.
                                    122

-------
Another possibility would be removal of coarse solids following aeration
in a batch system.  This could increase the time period to reach a
selected maximum mixed liquor total solids concentration and thus increase
storage time by 15 to 30 percent.

The centrifuge test results (Table 24) indicate that this process is
capable of a high degree of solids removal from oxidation ditch mixed
liquor.  Also, it results in a concentrated sludge which can reduce the
volume of material requiring ultimate disposal in comparison to direct
disposal of mixed liquor.  The supernatant can be recycled back into the
aeration systems.  Production of thickened solids containing 16 percent
total solids would reduce sludge volume to approximately that of the
original raw waste.  This best can be understood by considering the follow-
ing example.  Fresh poultry manure contains roughly 25 percent total
solids.  If biological solids destruction occurred without dilution for
aeration, 36 percent total solids destruction would result in the reduc-
tion in total solids to 16 percent.  This is without any dilution to
increase volume.  Therefore, following dilution for and solids destruction
during aeration, removal of dilution water by centrifugation to attain
a sludge total solids concentration of 16 percent would result in a
waste volume equal to the original volume of the raw waste.   This
suggests that increased waste volume requiring ultimate disposal is not
necessarily a characteristic of aeration.  This would serve to overcome
a commonly cited disadvantage of aeration systems; increase in volume of
the waste material due to dilution.

The tests results suggest that the use of centrifugation for liquid-
solids separation has significant potential.  However, due to the
limited extent of the testing, comment on the practicality of the
process is not possible at this time.  Factors such as cost and ease
of operation need to be evaluated along with more detailed testing
before the total potential of centrifugation can be realistically
evaluated.
                                    123

-------
 SEDIMENT ACCUMULATION
 The  problem  of  sediment accumulation encountered in this study indicates
 that the Manorcrest oxidation ditch design was inadequate in the area
 of hydraulics.  The observed reduction of mixed liquor velocity as
 sediment accumulation occurred decreased mixing which is important to
 the  biological  process.  Although biological process failure due to
 inadequate mixing did not occur, neither ditch was allowed to operate
 over an extended time period at mixed liquor velocities approaching
 zero.   If sediment removal to increase velocity had not occurred, it
 appears reasonable to assume that failure would occur due to inadequate
 mixing and dissolved oxygen transport.  This indicates that there is
 an interdependence between process and physical design.  In addition,
 sediment removal was a time consuming and labor intensive operation.

 The  cause of the sediment accumulation was inadequate initial mixed
 liquor velocity.  The accumulation of some sediment was not unexpected
 in that oxygen  transfer and not pumping capacity was the primary
 consideration in aerator sizing.  However, the design calculations and
 initial velocity measurements for Ditch II compared favorably with the
 recommended  minimum velocity for oxidation ditches of 0.38 m/sec
 (1.25 ft/sec) (21).

 Sedimentation was a major problem in both ditches, but it had a greater
 adverse impact  in Ditch II.  Accumulations of sediment were greater
 and  the secondary effects more pronounced in Ditch II even though
 Ditch I had  lower mixed liquor velocities.  The reason for this
 phenomenon is not clear although it appears to be related to the
 type of aeration unit.  This was the only physical difference between
 the  two ditches.

Although accumulation of some sediment was not totally unexpected,
 it was assumed that the accumulations would reach an equilibrium.   It
                                   124

-------
was theorized that as the sediments reduced the channel cross-sectional
area, velocity would increase until scour occurred.  In fact, the
reverse occurred.  As sediment accumulation increased, velocity
decreased thereby causing more settling.  This process continued
until the velocity approached zero as was demonstrated on several
occasions in Ditch II.  Use of the Manning uniform equation for open
channel flow, Equation 20, to describe flow in an oxidation ditch
provides a possible explanation for the effect of the sediments on
mixed liquor velocity.

                         V , L486 R2/3 sl/2                        (2fl)

where     V = velocity
          N = coefficient of roughness
          R = hydraulic radius, cross-sectional area
              divided by the wetted perimeter
          S = slope

Assuming a constant pumping capacity and therefore a constant equivalent
to the energy line slope, the equation predicts velocity will decrease
as the coefficient of roughness increases and/or as the hydraulic
radius decreases.  Sediment accumulations caused both to occur.   The
accumulation of 25.4 cm (10 in.) of sediment as occurred in Ditch II
during 1973-74 reduced the hydraulic radius by 41  percent.   Assuming
both S and N remained constant, it was calculated that the  resultant
velocity reduction would be 29 percent.

Several factors affect the coefficient of roughness in the  Manning
equation (59).  Included are surface roughness and channel  irregu-
larity.  Surface roughness is a function of the shape and size of the
grains of material forming the wetted perimeter.  A significant difference
should not exist between concrete and poultry manure solids.  The
sediment accumulations did significantly increase channel irregularity
                                   125

-------
as shown in Figures 30 through 33.  Irregularity can increase the
value of N as much as 0.02 above the value for a smooth channel (59).
Assuming an initial value of N of 0.016 for a concrete channel and an
increase of 0.02 for irregularity, the effect of the increase coefficient
of roughness and decreased hydraulic radius was calculated for Ditch II.
The results of this calculation predicted that the initial velocity of
0.38 m/sec (1.25 ft/sec) would decrease to 0.12 m/sec (0.39 ft/sec)
which agrees reasonably well with observed performance.   The problem
with the original theory, which assumed that scour would cause sedi-
ment accumulations to reach an equilibrium, lies in the failure to
recognize that friction losses are not constant.

It is clear that sedimentation in oxidation ditches should be prevented.
Therefore, mixed liquor design velocities in these systems should
equal or exceed the scour velocity necessary to keep the heaviest
manure particles in suspension.  The scour velocity for poultry manure
was calculated to be 0.53 m/sec (1.74 ft/sec) using the following
relationship:
where     Vu = horizontal velocity that will produce scour
           n
           s = specific gravity of particles
           d = diameter of particles
           k = constant dependent on type of material
               being scoured
           f = Darcy - Weisbach friction factor

The values used in this calculation and their sources are as follows:

           s = 2 gms/cm3 (58)
           d = 1.19 mm maximum (58)
                                   126

-------
            k = 0.06  (60)
            f = 0.02  (60)
This indicates that the currently recommended minimum design velocity
of 0.38 m/sec (1.25 ft/sec) is not adequate for poultry wastes.

This conclusion has a significant impact on the design of these
systems.  Analysis of results has shown that the Thrive rotor's oxygen
transfer capacity was excessive in comparison to the combined carbona-
ceous and nitrogenous oxygen demand.  However, the results of this
analysis also indicate  that the unit was under-sized in terms of pump-
ing capacity.  Two methods of increasing pumping capacity exist.  They
are increasing the size of the aeration unit or using a supplemental pumping
device.  Both solutions will increase capital and operating costs and
may make aeration economically unattractive.

An alternative solution may lie in improvement of the hydraulic design
of oxidation ditch channels to reduce friction losses, as suggested by
Simons (61).  This would result in velocity increases without increasing
energy input.  Opportunities exist to reduce friction losses through
improvement of cross-section channel geometry and the geometry of the
semi-circular curves  connecting the two linear channels.  As can be seen
in the Manning equation, increasing the hydraulic radius will increase
velocity.  This can be achieved by decreasing the wetted perimeter in
relation to the liquid cross-sectional area.  However, the potential for
increasing velocity by this approach is small.

Based upon a comparison of velocity in Manorcrest Ditch II and an oxida-
tion ditch discussed  by Windt, et al. (62), it appears that significant
increases in velocity at a fixed energy input can be achieved by in-
creasing the radius of curvature of the semi-circular connecting channels.
Details of both ditches are presented in Table 34.  Although volume per
                                     127

-------
Table 34.  COMPARISON OF THE PHYSICAL DETAILS OF
           MANORCREST DITCH II  AND AN OXIDATION
           DITCH DISCUSSED BY WINDT,  et al

Manorcrest Oxidation Ditch'
Ditch II Discussed by
Windt, et al. (62)
Length of straight
channel section
Channel width
Liquid depth
Radius of curvature
of senri -circular sections
Volume
Rotor

Rotor length
Immersion depth
Volume per unit
rotor length
Velocity
39.6 m
2.3 m
51 cm
1.6 m
106 m3
Thrive H-805
r
1.7 m
13 cm
62.4
0.38 m/sec
27.7 m
2.4 m
56 cm
3.8 m
93.5 m3
Thrive H-805

1.7 m
15 cm
55
0.61 m/sec
                       128

-------
unit length of rotor and therefore energy input was less in the Manorcrest
ditch, it does not appear that this factor alone is responsible for the
significant difference in liquid velocity.

The greatest geometrical difference between the two ditches was the
radius of curvature of the semi-circular sections.  In a discussion of
energy loss resulting from  curve resistance, Chow (59) states that the
coefficient of curve resistance, f , is a function of several  factors.
                                  \f
They 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
             \f
Assuming a constant velocity and therefore Reynolds number, the only
parameter that varies significantly between the two ditches is rc/b.
The value of this ratio is 0.7 for the Manorcrest ditch and 1.6 for the
oxidation ditch discussed by Windt.  The effect of this difference on
f  can not be calculated.  However, experiment results reported by Shukry
 w
(63) showed a decrease in f  from 0.91 to 0.32 when r /b increased from
0.5 to 1.0.  Values of the other parameters in the study where:

               R = 7.5 x 10"4
             y/b = 1
          a/1800 = 0.5

While this result does not directly apply to the comparison under
consideration, it does illustrate the effect of the radius  of  curva-
ture in a nonlinear channel on f .  The effect of f  on energy loss due
                                c                  "-
to curve resistance in terms of velocity head can be expressed as follows:

                             *f - fc £                              <22)
                                    129

-------
where     hf = velocity head
           V = mean velocity in the section
           g = acceleration due to gravity

It  can  be seen that as f  increases, hf to maintain a constant velocity
                        \*             *
also increases.

Unfortunately, precise relationships concerning flow in nonlinear open
channels have not been defined.  However, it appears that velocity in
oxidation ditches can be increased without increasing energy input by
improving hydraulic design.  This suggests that the current practice
of  adapting oxidation ditches to animal  housing patterns such as placing
channels below cages may need revision.

FOAMING AND EXCESS WATER
As  indicated in the results section, foaming problems of a nuisance
nature were encountered in this study.  The causes of the foaming are
not clear.  Inadequate oxygen supply resulting in anaerobic conditions is
often cited as the cause of foam.  However, foaming problems did not
occur in Ditch l, which was the minimally aerated system, but rather
in Ditch II where residual dissolved oxygen concentrations were maintained.

Accumulated sediments have also been suggested as a causative agent of
foaming in a study of aerobic treatment of swine wastes (47).  However,
sediment accumulations were present in both Manorcrest ditches but
foaming only occurred in Ditch II.  Based upon the observations during
this study and from previous experience, it appears that there are
several factors which will cause foaming.  However, relationships are
not clear.   With the exception of an overloaded condition, it appears
that adequate velocity to maintain continuous foam movement can prevent
foam from becoming a problem.
                                    130

-------
In a pilot plant study, it was reported that no overflow occurred from
an oxidation ditch treating poultry wastes  (6).  In this study, it was
necessary to add water to offset evaporative losses.  It appears that
the same situation should occur under commercial conditions if leakage
from the bird watering system is eliminated.  This can be accomplished
through the use of a trough type watering system.  Water addition via
manure is low and was calculated to be approximately 79 £ per 1000
birds per day (21 gal per 1000 birds per day) at Manorcrest.  Evaporative
losses should offset the quantity of water added as manure.

ECONOMIC IMPACT
The practicality of aeration as a poultry waste management tool 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 not opportunity to pass 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.  However, a 1973
survey (64) of 40 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 1971
and 1972 (65,66,).  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 baselines for economic assessment.  This procedure allows determination
of economic impact in terms of efficient production resulting from
skillful  management.  Egg production costs in New York State for the
years 1971-73 are presented in Table 35.  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 Ibs) of feed per dozen eggs and 20 dozen eggs
marketed per hen year.  The effect of good management is reflected
in the selected feed conversion efficiency and production values which
are above average for the three years evaluated.
                                    131

-------
            Table 35.  NEW YORK STATE EGG PRODUCTION COSTS
                       (64,65,66)

Cost /hen-year
Return to capital @9%
Labor*
Feed
Hen**
Building repairs
Electricity
Taxes
Insurance
Total
Production cost/
dozen eggs
1973
$ .67
.94
5.12
1.75
.03
.11
.07
.11
$8.80
0.44
1972
$ .56
.87
3.23
1.75
.04
.10
.06
.09
$6.70
0.335
1971
$ .62
1.05
3.56
1.75
.04
.09
.07
.09
$7.27
0.364
* Includes operator's labor
**Estimated cost $2.00/bird,  less salvage value of $.25/bird
                                  132

-------
 The capital costs  of  the Manorcrest aeration systems,  Table  30, are
 high  in comparison to those previously reported  for another  application
 of oxidation  ditches  for poultry waste treatment.    That  system,
 Houghton's, was  also evaluated by personnel  from  the Cornell  Agricultural
 Waste Management  Program (16).   An itemized comparison of the capital
 costs for  both  systems per 1000 birds  is  presented  in Table  36.

 As shown,  the major factor in the high capital cost of the Manorcrest
 systems is the  construction cost for conversion  of  the four manure
 collection pits into  two oxidation ditches.   One factor contributing
 to the higher costs at Manorcrest was  the smaller number  of birds, 8,000,
 in comparison to  the  15,000 birds at the  Houghton Farm.   Both conversions
 were  similar  requiring the connection  of  four manure collection pits
 to form two oxidation ditches.   Since  the Houghton  system served more
 birds, the result  was a lower unit cost.

 However, this does not account for the total  difference.  Another factor
 was the decision  to place the connecting  channels beyond  the ends of the
 cage  rows at  Manorcrest which increased construction costs.  This placed
 these channels  in  the service alleys at each  end of  the cage rows and
 necessitated  the construction of a floor  system  capable of supporting
 workers and feed and  egg carts  over the connecting channels.  Conversely,
 the connecting  channels were placed under the cages at the Houghton Farm.

 The use of precast concrete settling and  storage tanks also increased
 the capital cost of the Manorcrest systems.   Estimation of costs for
 alternative approaches  to liquid-solid separation and storage awaits
 the results of more detail  investigation  into this area.

 The energy costs for  aeration  determined  in this study, Table 31, were
 significantly lower than  those  previously reported.  Power costs of
 two to four cents  per dozen eggs  have  been reported for a pilot plant
scale oxidation ditch  (67).  and  one cent  per  dozen for a full scale,
 15,000 bird, oxidation  ditch  system (16).  The impact of energy costs
                                   133

-------
      Table 36.  COMPARISON OF CAPITAL COSTS PER 1,000 BIRDS,
                 MANORCREST FARMS AMD HOUGHTUN'S POULTRY FARM
                            	Manorcrest	         Houghton
                            Ditch I         Ditch II
Construction                $1,092          $1,092             $187
Settling tanks                 380             380
Aeration units                 375             530              480
                            $1,847          $2,002             $667
Annual capital cost
per 1,000 hens              $  222          $  248             $ 95
Annual capital cost
per dozen eggs               .0111           .0124              .0047
                                  134

-------
for the  four levels of oxygen  transfer evaluated in this study on
production costs are presented  in Table 37.  For three years 1971-73,
energy costs of aeration for odor control would have increased production
costs by a maximum of one percent.  Even at the highest level of oxygen
transfer where transfer capacity exceeded calculated total demand by
approximately 45 percent, the maximum increase in production costs
would have been only two percent.

The total economic impact of the use of aeration for the different
designs and modes of operation  on egg production costs, for the years
1971-73, are summarized in Table 38.  The increased total  cost of
aeration for odor control never exceeded 5 percent even with the high
capital costs characteristic of this study.  The cost of electricity
was $.0201 per kwhr for this study and may differ elsewhere.

This study has demonstrated that process design based on fundamental
concepts of the biological waste treatment process and oxygen transfer
can reduce energy costs for aeration.  This point is illustrated by
comparison Of the energy costs  between the Houghton system and Manorcrest.
The design and operation of the Houghton system was based on empirical
parameters where as a more fundamental approach was used for Manorcrest.
Energy cost per dozen eggs for  odor control at Houghton's was reported
to be $0.0100 (16) in comparison to $0.0056 per dozen eggs at Manorcrest
(Table 31).

In evaluating these energy costs, it is important to realize that energy
costs are also a function of the aerator oxygen transfer efficiency.
Both aeration units in this study delivered approximately 1500 gms 02 per
kwhr (2.5 Ibs 02 per hp-hr).  Other types of surface aeration equipment
with higher efficiencies, 2400  gms 02 per kwhr (4 Ibs 02 per hp-hr) are
available (60).  A turbine aeration system evaluated in a pilot plant
scale study of poultry wastes has been reported to have an oxygen
transfer efficiency of approximately 3000 gms 02 per kwhr (5 Ibs 02 per
                                   135

-------
Table 37.  EFFECT OF POWER COSTS FOK AEROBIC STABILIZATION
           ON EGG PRODUCTION COSTS

Level
of Oxygen
Transfer Capacity,
gms Op/I






000 bird-hrs.
351
520

790 &
815

Degree of
Stabilization

Odor control
Nitrification-
denitrifi cation
Potential
nitrogen
conservation
Percentage
Increase In
Egg Production
1973 1
0.8

1.1


1.6
972
1.0

1.4


2.0
Costs
1971
0.9

1.3


1.8
Table 38.   EFFECT OF TOTAL COSTS FOR AEROBIC STABILIZATION
           ON EGG PRODUCTION COSTS

Level of Oxygen
Transfer Capacity
gms 02/1000 bird-hrs.
351
520
790 &
815
Degree of
Stabilization
Odor control
Ni trifi cation-
den itrifi cati on
Potential
nitrogen
conservation
Percentage Increase In
Egg Production Costs
1973
3.8
4.1
4.9
1972
5.0
5.3
6.4
1971
4.6
4.9
5.9
                            136

-------
hp-hr) (42).  The use of more efficient aeration equipment would reduce
operating costs but may require a system different from the oxidation
ditch.

The differences in capital costs between Manorcrest and the Houghton
farm suggest that opportunities for cost reduction are available.   The
location of the semi-circular connecting channels beyond the end of the
cage rows in the service alleys at Manorcrest necessitated excavation
and construction of a floor system which increased construction costs.
In contrast, these channels were placed under the cages and reduced
construction costs for the Houghton system.  Use of an earthen lagoon
in place of precast concrete tanks would also reduce capital costs.
Realization of  these  lower capital costs along with the low power costs
demonstrated in this  study should result in further improvements in
what appear to  be  reasonable costs.
                                    137

-------
                              REFERENCES

 1.   Jasper, A.M.  Some Statistical Highlights of the Poultry Industry.
     American  Farm Bureau Federation.  '1973.

 2.   The  College of Agriculture and Environmental Sciences, Rutgers
     University.  Poultry Manure Disposal by Plow Furrow Cover.  Final
     Report Grant EC-00254-03, U.S. Environmental Protection Agency.
     1972.  108 p.

 3.   Bartlett, H.D. and L.F. Harriot.  Subsurface Disposal of Liquid
     Manure.   In:  Livestock Waste Management and Pollution Abatement.
     ASAE.  St. Joseph, Michigan.  1971.  p. 258-260.

 4.   Loehr, R.C., T.B.S. Prakasam, E.G. Srinath, T.W. Scott and T.W. Batemen.
     Design Parameters for Animal Waste Treatment Systems -- Nitrogen
     Control.  Environmental Protection Technology Series Report.  U.S.
     Environmental Protection Agency.  In press.  142 p.

 5.   Vickers, A.F. and E.J. Genetelli.  Design Parameters for the
     Stabilization of Highly Organic Manure Slurries by Aeration.  Proc.
     Agric. Waste Management Conference, Cornell University, Ithaca,
     New York.  1969.  p. 37-49-

 6.   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.

7.  Federal  Register.  Effluent Guidelines Standards, Feedlots Point
    Source Category.  Washington, D.C.   39:5704-5708.  February, 1974.
                                     138

-------
 8.  Sobel, A.T.  Physical Properties of Animal Manure Associated
     with Handling.  In:  Management of Farm Animal Wastes.  ASAE.
     St. Joseph, Michigan.  1966.  p. 27-32.

 9.  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.

10.  Hashimoto, A.G.  Characterization of White Leghorn Manure.  Proc.
     Agric. Waste Management Conference.  Cornell Univeristy, Ithaca,
     New York.  1974.  p. 141-152.

11.  Prakasam, T.B.S., R.C. Loehr, P.Y. Yang, T.W. Scott,  and T.W.  Batemen.
     Design Parameters for Animal Waste Treatment Systems.    Environmental
     Protection Technology Series Report No. EPA 660/2-74-063.   Washington,
     D.C.  1974.  218 p.

12.  Nieswand, S.P.  An Evaluation of a Full-Scale In-House Oxidation
     Ditch for Poultry Waste.  Unpublished M.S. Thesis, Cornell University,
     Ithaca, New York.  1974.  140 p.

13.  Development Document for Effluent Limitation Guidelines and Standards
     of Performance for New Sources for the Feedlots Point Source Category.
     U.S. Environmental Protection Agency, Washington, D.C., February,  1974.
     (U.S. Government Printing Office Stock No. 5501-00842).

14.  Morris, G.R., Unpublished data.  Cornell University Agricultural
     Waste Management Program.  1975.

15.  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.
                                     139

-------
 16.   Martin, J.H., R.C. Loehr, A.C. Anthonisen, and S.P. Nieswand.
      Aerobic Treatment of Poultry Wastes.  ASAE Paper No. 74-4029.
      St.  Joseph, Michigan.  1974.  35 p.

 17.   Holmes, B.J.  Effect of Drying on the Losses of Nitrogen and
      Total Solids from Poultry Manure.  Unpublished M.S. Thesis, Cornell
      University.  1973.  97 p.

 18.   Hashimoto, A.G.  Aeration Under Caged Laying Hens.  ASAE Paper
      No.  NAR-71-428.  St. Joseph, Michigan.  15:1119-1123, 1972.

 19.   Dunn, G.G. and Robinson, J.B.  Nitrogen Losses through Denitrification
      and  Other Changes in Continuously Aerated Poultry Manure.  Proc.
      Agric. Waste Management Conference, Cornell University, Ithaca,
      New  York.  1972.  pp. 545-554.         Ğ

 20.   Prakasam, T.B.S., E.G. Srinath, A.C. Anthonisen, J.H. Martin, Jr.,
      and  R.C. Loehr.  Approaches for the Control of Nitrogen with an
      Oxidation Ditch.  Proc. Agric. Waste Management Conference, Cornell
      University, Ithaca, New York.  1974.  p. 421-435.

 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.  Canada Department of Agriculture.  Canada Animal Waste Management
     Guide.  Publication 1534.  Ottawa, Ontario.  1974.

24.  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.
                                    140

-------
25.  Owens, J.D., M.R. Evans, F.E. Thuder, R. Hlssett, and S. Baines.
     Aerobic Treatment of Piggery Wastes.  Water Research 7:1745-1766,
     1973.

26.  Monod, 0.  The Growth of Bacterial Cultures.  Ann. Rev. Microbiology.
     3:371-394, 1949.

27.  Lawrence, A.H. and P.L. McCarty.  Unified Basis for Biological  Treat-
     ment Design and Operation.  J. Sanitary Eng. Div., ASCE, 96:757-778,
     1970.

28.  Stensel, H.D. and 6.L. Shell.  Two Methods of Biological Treatment
     Design.  J. Water Poll. Control Fed.  46:271-283, 1974.

29.  Woods, J.L. and J.R. O'Callaghan.  Mathematical Modelling of
     Animal Waste Treatment.  J. Agric. Eng. Res.  19:245-258, 1974.

30.  Loehr, R.C., T.B.S. Prakasam, E.G. Srinath, and Y.D.  Joo.  Development
     and Demonstration of Nutrient Removal From Animal Wastes.  Environ-
     mental Protection Technology Series Report No. EPA-R2-73-095,  U.S.
     Environmental Protection Agency.  1973.  340 p.

31.  Downing, A.L., H.A. Painter, and G. Knowles.  Nitrification in the
     Activated Sludge Process.  Journal Institute of Sewage Purification.
     Part 2.  1964.  p. 130-158.

32.  Loehr, R.C.  Agricultural Waste Management.  New York, Academic
     Press, 1974.  242 p.

33.  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.
                                    141

-------
 34.  Downing, A.L. and A.G. Boon.  Oxygen Transfer in the Activated
     Sludge Process.  Air and Water Pollution 5:131-148, 1963.

 35.  O'Connor, D.J.  Effects of Surface Active Agents on Reaeration.
     Air and Hater Pollution 5:123-130, 1963.

 36.  Gaden, E.L., Jr.  Aeration and Oxygen Transport in Biological
     Systems - Basic Considerations.  In:  Biological Treatment of
     Sewage and Industrial Wastes.  New York, Reinhold Publishing
     Corp., 1956.  p. 172.

 37.  Baker, D.R., R.C. Loehr, and A.C. Anthonisen.  Oxygen Transfer
     at High Solids Concentrations.  J. Environ. Eng. Div., ASCE.
     101:759-774.  1975.

 38.  Gameson, A.L. and K.G. Robertson.  The Solubility of Oxygen in
     Pure Water and Sea Water.  Journal of Applied Chemistry.  5:502,
     1955.

 39.  Water Pollution Control Federation.  Aeration in Hastewater
     Treatment - Manual of Practice No. 5.  Washington, D.C.  1970.

 40.  Anderson, D.R. and M. Kurd.  Study of Complete Mixing Activated
     Sludge.  J. Water Poll. Control Fed.  43:422-432, 1971.

 41.  Pfeffer, J.T., F.C. Hart, and L.A. Schmid.  Field Evaluation of
     Aerators in Activated Sludge Systems.  Proc. 23rd Industrial Waste
     Conference,  Purdue University, 183-194, 1968.

42.  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.
                                   142

-------
43.  Stratton, F.E. and P.L. Mccarty.  Prediction of Nitrification
     Effects on the Dissolved Oxygen Balance of Streams.  Environ-
     mental Science and Technology.  1:405-410, 1972.

44.  Terashima, S., K. Koyama, and Y. Mazara.  In:  Biological Sewage
     Treatment in a Cold Climate Area.   (R.S. Murphy and D. Nyguist,
     eds.).  College, Alaska.  EPA Report 16100 EXH.  University of
     Alaska, 1971.  p. 263-385.

45.  Fair, G.M. and J.C. Geyer.  Elements of Water Supply and Waste-
     water Disposal.  John Wiley and Sons, New York, 1958.  p. 329.

46.  Jones, D.D., D.L. Day, and J.C. Converse.  Oxygenation Capacities
     of Oxidation Ditch Rotors for Confinement Livestock Buildings.
     In:  Proc. of the 24th Annual Purdue Industrial Waste  Conference,
     Lafayette, Indiana, Purdue University, 1969. p. 191-208.

47.  Martin, J.H.  Unpublished Data.  Cornell University Agricultural
     Waste Management Program.  1972.

48.  McKinney, R.E. and R. Bella.  Water Quality Changes in Confined
     Hog Waste Treatment.  Project Report:  Kansas Hater Resources
     Research Institute.  University of  Kansas, Lawrence, Kansas.
     1967.  88 p.

49.  American Public Health Association.  Standard Methods  for the
     Examination of Water and Wastewater.  13th ed.  New York, 1971.

50.  McKenzie, H.A. and H.S. Wallace.  The Kjeldahl Determination of
     Nitrogen:  A Critical Study of Digestion Conditions, Temperature,
     Catalyst, and Oxidizing Agent.  Aust. J. Chem  (Sidney) 7:55-71.  1954.
                                    143

-------
 51.   Prakasam, T.B.S., E.G. Srinath, P.Y. Yang, and R.C. Loehr.
      Analyzing Physical and Chemical Properties of Liquid Waste.
      In:  Standardizing Properties and Analytical Methods Related
      to Animal Waste Research.  ASAE.  St. Joseph, Michigan.  1975.
      p. 114-166.

 52.   Montgomery, H.A.C. and J.F. Dymock.  The Determination of Nitrite
      in Water.  Analyst 86:414-416.  1961.

 53.   Jeris, J.S.  A Rapid COD Test.  Water and Wastes Engineering.
      4:89-91, 1967.

 54.   Srinath, E.G., R.C. Loehr, and T.B.S. Prakasam.  Nitrifying Organism
      Concentrations and Activity.  Accepted for Publication. J. Environ.
      Eng. Div., ASCE.

 55.   Anthonisen, A.C., R.C. Loehr, T.B.S. Prakasam, and E.G. Srinath.
      Inhibition of Nitrification by Ammonia and Nitrous Acid.  (Presented
      at the 47th Annual Conf., Water Pollution Control Federation, Denver,
      Colorado, October 1974) and accepted for publication by the J. Water
      Poll. Control Fed.

 56.   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.

57.   Dick, R.I.  Role of Activated Sludge Final Settling Tanks.  J. Sanitary
      Eng.  Div., ASCE  96:423-436, 1970.

58.  Sobel,  A.T.   Physical Properties of Animal Manures Associated with
     Handling.  In:  Farm Animal Wastes.  ASAE.  St. Joseph, Michigan.
     1966.  p. 27-32.
                                     144

-------
59.  Chow, V.T.  Open-Channel Hydraulics.  New York, McGraw-Hill Book
     Company, 1959.  680 p.

60.  Metcalf and Eddy, Inc.  Wastewater Engineering. New York, McGraw-
     Hill Book Company, 1972.  782 p.

61.  Simons, D., D.D. Jones, and A.C. Dale.  Oxidation Ditch Analysis
     and Field Evaluation of the Aerob-A-Jet.  Proc. Agricultural Haste
     Management Conference, Cornell University, Ithaca, New York.  1974.
     p. 436-454.

62.  Windt, T.A., N.R. Bulley, and L.M. Staley.  Design, Installation,
     and Biological Assessment of a Pasveer Oxidation Ditch on a Large
     British Columbia Swine Farm.  In:  Livestock Waste Management and
     Pollution Abatement.  ASAE.  St. Joseph, Michigan.  1971. p. 213-^16.

63.  Shukry, A.  Flow Around Bonds in an Open Flume.  Transactions, ASCE.
     115:751-779, 1950.

64.  Bratton, C.A., and G.H. Thacker.  1973 Poultry Farm Business Summary.
     Dept. of Agricultural Economics, Cornell University, Ithaca, New York.
     1974.  34 p-

65.  Bratton, C.A., and G.H. Thacker.  1972 Poultry Farm Business Summary.
     Dept. of Agricultural Economics, Cornell University, Ithaca, New York.
     1973.  34 p.

66.  Bratton, C.A., and G.H. Thacker.  1971 Poultry Farm Business Summary.
     Dept. of Agricultural Economics, Cornell University, Ithaca, New York.
     1972.  34 p.

67.  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.

                                    145

-------
                              SECTION  IX

                              APPENDICES


FIGURE                          TITLE                             PAGE

 Al              Motor performance  data for  the  brush
                 aeration unit                                    147

 A2              Motor performance  data for  the  Thrive
                 Center Aeration Unit                              148

 A3              Motor performance  data for  the  propeller
                 drive unit,  115 rpm                               149

 A4              Motor performance  data for  the  propeller
                 drive unit,  230 rpm                               150
TABLE                           TITLE                             PAGE

 Al               Relationships  Between  SRT  and  Treatment
                 Effeciencies                                      151
                                  146

-------
2.2

2.Q_

 1.8 —

 1.6

 1.4

 1.2

 1.0

0.8

 0.6

0.4

 0.2
                              KILOWATTS,
                                     EFFICIENCY
                         ELECTRA MOTORS OIV -
                         JEFFERY MANUF. CO.
                         2 HP, 10, 60 Hz, 230 VOLTS,
                         345 RPM. GEARHEAD MOTOR
60

50

40

30

20
                                                            UJ
0    .2     4    .6    .8    1.0    1.2   1.4   1.6    1.8   2.0
                SHAFT  HORSEPOWER
                                                        10
Figure Al.  Motor Performance data for the  brush aeration unit

-------
oo
                                                    CENTURY ELECTRIC COMPANY
                                                    5 HP,  10, 60HzM 230 VOLTS,
                                                    1750 RPM, TYPE CS,
                                                    FRAME 2I3T.
                                                                                40
o
LtJ
O
iZ
LL
LU
§*•
                                                                                20
                                               2          3
                                        SHAFT HORSEPOWER
                     Figure A2.  Motor performance data for the Thrive Center Aeration Unit

-------
    800
    6OO —
ID
Q.
   400 —

   200
                                  WATTS
U.S. MOTORS *S.M.3030 D.C. PKG.
UNIT with  BROWNING  107 SM 05
SHAFT MOUNTED REDUCER. 3 HP,
60 Hz, I 0 , 230 VOLTS, 115 RPM.
                              40
30

     >
     o

     UJ

20   y
     U.
     UJ

     $5

10
                 O.I         0.2        0.3
                   SHAFT  HORSEPOWER
                           0.4
       Figure A3.   Motor performance data for the propeller
                  drive unit, 115 rpm
                           149

-------
en
o
   2,000

    1300

    1,600

    1,400
H-
£  '>2°o
z
  1,000

    800

    600

    400

    200

                                 EFFICIENCY
                                            U.S. MOTORS *SM-3030 D.C.Pkg. UNIT
                                            with BROWNING I07SM05 SHAFT
                                            MOUNTED REDUCER. 3 HP, 10,
                                            60 Hz, 230 VOLTS,  230 RPM
                                                I
I
                                                                           60
                                                                           50
                                                                           40
                                                                               o
                                                                               o
                                                                               bJ
                                                                           30  0s
                                                                           20
                                     0.4        0.8        1.2
                                           SHAFT HORSEPOWER
          1.6
                     Figure A4.  Motor performance data for the propeller drive unit, 230 rpm

-------
Table Al.  RELATIONSHIPS BETWEEN SRT AND TREATMENT EFFICIENCIES

Ditch
No.
I
I
II
I
II
II
Length of
Equilibrium
Period
(Days)
25
56
14
56
34
36
Average Total
Solids Concentration,
13,
9,
21,
13,
19,
23,
760
960
570
550
800
830
Removal Efficiencies (%)
SRT
Days
10.5
15.0
18.0
21.0
27.0
36.5


Total
26.
38.
33.
37.
35.
40.
5
9
0
9
4
8
Solids

Volatile
37.
50.
46.
49.
47.
54.
5
8
5
1
7
3
COD
22.
32.
36.
31.
31.
35.
4
9
2
2
4
0
Organic
Nitrogen
49.0
55.0
58.5
60.4
64.7
63.3

-------
                                    TECHNICAL REPORT DATA
                             (Please read Instructions on the reverse before completing)
 1. REPORT NO.
    EPA-600/2-76-186
                                                            3. RECIPIENT'S ACCESSION NO.
 4. TITLE AND SUBTITLE

  Demonstration of Aeration Systems  for  Poultry Wastes
               5. REPORT DATE
               October   1975 (Issuing
               6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)
                                                            8. PERFORMING ORGANIZATION REPORT NO.
  J.H.  Martin,  Jr.  and R.C. Loehr, Cornell  University,
                                    Ithaca,  NPW Ynrk
 9. PERFORMING ORGANIZATION NAME AND ADDRESS
                    flanorcrest Farms
                    5322 Munro Road
                    Camillus, NY   13031
               10. PROGRAM ELEMENT NO.

                  1HB617
               11. CONTRACT/GRANT NO.

                    5800863
  12. SPONSORING AGENCY NAME AND ADDRESS
  Environmental  Research Laboratory - Athens,  GA
  Office  of Research and Development
  U.S.  Environmental Protection Agency
  Athens,  Georgia  30601
               13. TYPE OF REPORT AND PERIOD COVERED
                  Final  Report
               14. SPONSORING AGENCY CODE

                   EPA/600/01
 15. SUPPLEMENTARY NOTES
 16. ABSTRACT
  A full scale  study demonstrated the potential  of aeration systems to reduce  the water
  and air pollution potential of poultry wastes  under commercial conditions.   The
  nerformance of  two oxidation ditches, each receiving the wastes from approximately
  4000 layinn hens, was  monitored and evaluated.

  The relationships between two design and operational variables and system performance
  were examined.   The variables were level of oxygen  supply and solids retention  time.
  It was observed  that an oxygen input equivalent  to  the exerted carbonaceous  oxynen
  demand provided  a high degree of odor control.   Increase in oxynen supply to also
  satisfy the exerted nitrogenous oxygen demand  resulted in nitrification which termi-
  nated ammonia desorotion.   Subsequent nitrogen losses were the result of denitrifica-
  tion relationships between removals of total solids, volatile solids, COD, and  organic
  nitrogen in aerated poultry wastes were developed.

  Two major problem areas were identified and examined.  The first was the removal  and
  concentration of  residual  solids to maximize oxygen transfer efficiency and  minimize
  the volume of material  requiring ultimate disposal.   The second was sedimentation of
  solids  in the oxidation ditch channel  which reduced and in several instances stopped
  nixed  liquor circulation.	
 7.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
  Capitalized  Cost,  Oxidation, Odor  Control,
  Operating  Costs,  Waste Treatment,  Poultry
  b.lDENTIFIERS/OPEN ENDED TERMS
    Poultry manure, Oxida~
    tion  ditch, Nitrogen
    transformations, nitrogeji
    losses, liquid-solids
    separation, liquid aera-
    tion  systems, COD
    removal.
                                                                            COSATI Field/Group
02/C/E
 3. DISTRIBUTION STATEMENT
   Release Unlimited
  19. SECURITY CLASS (ThisReport)
    Unclassified
                                                                          21. NO. OF PAGES
                                                                               164
                                               20. SECURITY CLASS (Thispage)

                                                 Unclassified
                             22. PRICE
EPA Form 2220-1 (9-73)
152
                                                   r U. S. GOVERNMENT PRINTING OFflCE. 1977-757-056/5529 Region No. 5-1

-------