EPA 660/2-74-023
April 1974
                        Environmental Protection Technology Series
    Odors  From  Confined
     Livestock Production

                                  Office of Research and Development
                                  U.S. Environmental Protection Agency
                                  Washington, D.C. 20460

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                                               EPA-660/2-74-023
                                               April  1974
    ODORS FROM CONFINED LIVESTOCK PRODUCTION

               A  State-of-the-Art
                 J.  Ronald Miner
       Agricultural  Engineering Department
             Oregon  State University
             Corvallis,  Oregon 97331
                  Project Officer

                  R.  Douglas Kreis
Robert S. Kerr Environmental  Research Laboratory
                   P.  0.  Box 1198
               Ada,  Oklahoma  74820
              Grant No.  R802009-01
             Program  Element 1BB039
                  Prepared  for
       OFFICE OF RESEARCH AND DEVELOPMENT
      U.S. ENVIRONMENTAL PROTECTION AGENCY
             WASHINGTON, D.  C.  20460
For aaie by the Superintendent of Document*, U.S. Government Printing Office Washington, B.C. 2W02 - Price $1.70

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                                   ABSTRACT

Current livestock production techniques result in the generation of odors
which have become a source of conflict between livestock producers and
society.  The odorous gases responsible for the nuisance are principally
low molecular weight compounds released during anaerobic decomposition of
manure.  Manure management systems which control or modify this decomposi-
tion offer the greatest potential for odor control.

Research to identify the chemical compounds present in odorous air from
animal waste degradation has yielded about 45 compounds to date.  The
amines, mercaptans, organic acids and heterocyclic nitrogen compounds are
generally regarded as being of greatest importance.  Among the techniques
for odor control are:  (a) site selection away from populated areas and
where adequate drainage exists, (b) maintain the animal areas as dry as
possible and prevent the animals from becoming manure covered, (c) select
manure handling systems which utilize aerobic environments for manure
storage, (d) maintain an orderly operation free of accumulated manure and
runoff water, (e) practice prompt disposal of dead animals and (f) use
odor control chemicals when short term odor control is necessary, such as
when manure storage tank contents must be field spread.

This report was submitted in partial fulfillment of Project Number S-802009
under the partial support of the Office of Research and Monitoring, Envi-
ronmental Protection Agency.
                                      ii

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                                   CONTENTS
Sections                                                            Page

            Abstract                                                  ii

            List of Figures                                            v

            List of Tables                                            vi

            Acknowledgements                                          ix

            Summary                                                    1

I           Introduction to Odor Causes and Control                    5

II          Human Response to Odorants                                 9
                 Doctrine of Nuisance                                 11

III         Animal Response to Odorants                               15
                 Ammonia                                              15
                 Hydrogen sulfide                                     16
                 Mixed air pollutants                                 17

IV          Theory of Odor Perception                                 19
                 Mechanisms of perception                             22
                 Odor strength                                        25
                 Odor quality                                         28
                 Limitations of odor testing                          29
                 Supplementary instruments                            34

V           Relationship between Odor and pH                          37

VI          Desorption of Ammonia                                     39
                 From liquid poultry manure                           41
                 From cattle feedlots                                 41
                 From dairy pens                                      42
                 From anaerobic lagoons                               44

VII         Identification of Odorous Compounds                       45
                 Poultry manure                                       45
                 Cattle feedlots                                      49
                 Swine manure                                         51
                 Miscellaneous measurements                           54
                 Summary                                              54

VIII        Measurement of Specific Odorous Gas Concentrations        57
                 Ammonia                                              57
                 Hydrogen sulfide                                     59
                 Mercaptans                                           59
                 Volatile organic acids                               61

IX          Quantitative Measurement of Odors                         63
                 Odor strength                                        63
                 Scentometer                                          65
                 Odor quality                                         69
                                      iii

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Sections                                                            Page
X           Fecal Odor as Affected by Feed Additives                 71

XI          Chemical Treatment of Manure to Control Odors            75
                 Chlorine and lime                                   75
                 Potassium permanganate                              76
                 Hydrogen peroxide                                   77
                   Dairy manure                                      77
                   Swine manure                                      79
                   Poultry manure                                    79
                 Paraformaldehyde                                    80

XII         Use of Soil Filters to Remove Odorants                   85

XIII        Use of Proprietary Odor Control Chemicals                89

XIV         Waste Management Techniques to Minimize Odors            93
                 Open lots                                           93
                 Confinement buildings                               95
                 Animal-manure separation                            96
                 Manure storage                                      96
                 Anaerobic lagoons                                   98

XV          References                                              101

XVI         Appendices                                              109
                                      iv

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                                   FIGURES
Number
1           Anaerobic Breakdown of Proteins                           6
2           Bacterial Transamination                                  6
3           Pathways of Carbohydrate Breakdown                        6
4           Human Nasal Cavity                                       21
5           Olfactory Mucosa                                         21
6           Schematic Diagram of Scentoraeter                         67
                                       v

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                                    TABLES
Number                                                               Page

1            Use of Restrictive Environments to Control the            7
             Formation of Manure Odors by Anaerobic Decom-
             position

2            Characteristics of Farm Animal Manures                    8

3            Manure Production and Characteristics of Live-            8
             stock in Confinement, Per 1,000 Pounds Live
             Weight

4            Characteristics and Perceptible Concentrations            9
             of Various Substances in Air

5            Threshold Limit Values for Various Gases Asso-           11
             ciated with Animal Waste Odors

6            The Human Senses, Examples of Parameters Mea-            22
             sured and Alternate Information Sources

7            Basic Odor Ovuality Classifications as Described          28
             by Five Authors

8            pH Values for which Various Odorous Compounds            37
             are 50 percent Ionized at 25° C

9            Fraction of Total Ammonia Concentration Pre-             40
             sent as NH_ as a Function of Temperature and
             pH

10           Mean Ammonia Nitrogen Adsorption Rates by Di-            42
             lute Acid Traps from 27 July 1968 through 27
             February 1969 in Northeastern Colorado

11           Atmospheric Concentration of Distillable Ni-             43
             trogen  (Ammonia plus Amine) near Chino, Cal.

12           Average Weekly Adsorption of Distillable                 43
             (Ammonia plus Amine) Nitrogen by Acid Sur-
             face Traps near Chino, Cal., January  11 to
             February 15, 1972.

13           Ammonia Production by White Leghorn Layer Manure         48
             Added Daily to a  19 Liter  (Five Gallon) Carboy

14           Hydrogen Sulfide  Production by White  Leghorn Layer       48
             Manure  Added Daily to a  19 Liter  (Five Gallon)
             Carboy

                                      vi

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Number                                                              Page

15          Odorous Gas Detection and Identification Schemes         50
            Evaluated by Fosnaugh and Stephens

16          Odorous Compounds Identified from the Atmosphere         51
            in a Beef Cattle Confinement Chamber under Three
            Manure-Handling Programs

17          Gas Concentrations Measured in an Enclosed Swine         53
            Unit when Ventilated and when Ventilation had
            been Interrupted for Six Hours

18          Compounds Identified in the Air from the Anaero-         56
            bic Decomposition of Livestock and Poultry Manure

19          Calculated pH Values of Distilled Water in Equi-         58
            librium with Various Ammonia Concentrations in
            Air at 20° C

20          Ammonia Concentration (ppm) in Air Based on the          58
            pH of a Test Paper after 15 Seconds of Contact

21          Odor Intensity Index and Odorous Components in           66
            the Supernatant of Liquid Dairy Manure Receiv-
            ing Various Rates of Aeration

22          Dilution to Threshold Values with Various Ports          68
            Open on a Scentometer when an Odor is Barely De-
            tectable

23          Composition of Basal Diet for Animals on Fecal           71
            Odor Study

24          Treatments and Results - Trial 1.  Texas Tech            72
            University Swine Fecal Odor Study

25          Treatments and Results - Trial 2.  Texas Tech            72
            University Swine Fecal Odor Study

26          Treatments and Results - Trial 3.  Texas Tech            73
            University Swine Fecal Odor Study

27          Chromatographic Results After 2 Weeks - Trial            73
            3.  Texas Tech university Swine Fecal Odor Study

28          Chromatographic Results After 3 Weeks - Trial            74
            3.  Texas Tech University Swine Fecal Odor Study

29          Percent Weight Loss of Flake Paraformaldehyde            80
            when Exposed to Ammonia-Free Air at Various
            Temperatures
                                      vii

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Number                                                              Page
30          Percent Weight Loss of Flake Paraformaldehyde            81
            in Presence of Ammonia Gas from Chicken Manure
            at 22° C

31          Ammonia Content (ppm) of Headspace Gas Over 100          82
            Grains of Chicken Manure Treated with Various
            Levels of Paraformaldehyde

32          Bacterial Counts of Manure Samples on Brain              82
            Heart Infusion Agar After 11 Days of Exposure
            to Various Quantities of Paraformaldehyde

33          Manufacturers of Odor Control Products for Use           92
            in Controlling Manure Odors

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                                ACKNOWLEDGEMENT

The preparation of this report was supported in part by Grant No.  S-802009,
U.S. Environmental Protection Agency.  The cooperation of R.  Douglas Kreis,
Project Officer, Office of Research and Monitoring, Ada, Oklahoma, is grate-
fully acknowledged.

The technical and editorial assistance of Ted L. Willrich, Extension Agri-
cultural Engineer, and Richard Floyd, Agricultural Experiment Station Edi-
tor, Oregon State University, was instrumental in the completion of this
report.  The material in Section IV on the theories of odor perception was
taken, to a large measure, from a literature review paper presented by
Clyde L. Earth, Clemson University, during the July, 1970, meeting of the
American Society of Agricultural Engineers.

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                                    SUMMARY

The phenomenon of olfaction is complex.  Several models have been proposed
to explain the observations relative to odor perception and identification,
yet none of the models are entirely satisfactory.  Psychological aspects
of odor evaluation compound the difficulties in making objective measure-
ments of either odor strength or odor quality.  Correlations between the
chemical composition of air and its odor have proven more difficult than
anticipated.

Anaerobic decomposition of manure is a stepwise process in which complex
organic compounds are degraded to successively smaller, less complex mole-
cules.  Since, at a given moment, any or all of these intermediate com-
pounds may be present, the observed odor represents the sum of the indi-
vidual contributors.  Data indicate that the total odor may not represent
the  simple summation of individual contributors but that extensive inter-
action is occurring.

Research to identify the  chemical compounds present in odorous air from
animal waste degradation  has yielded about 45  compounds to date.  Even
though this list is undoubtedly incomplete, it indicates the complexity
of the situation and forewarns of the  difficulties to be encountered in
odor control.  The amines, mercaptans, organic acids, and heterocyclic
nitrogen compounds are generally regarded  as being of greatest odor sig-
nificance.

The  measurement of odors  has proven difficult  and current techniques are
not  entirely satisfactory.  Odor intensities  can be measured by determin-
ing  the volume of odor-free air required to dilute a volume of odorous
air  to a barely perceptible level.  Both laboratory and field equipment
are  available for this use.  In this technique,  the human nose is the de-
tector; therefore, considerable variation  due  to observer sensitivities
and  fatigue is common.  A liquid dilution  technique has been utilized for
evaluating  the odor of liquids in which odor-free water is used as the
dilutant.
                                        1

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Chemical techniques exist  for measuring  the  concentration  of many odorous
compounds produced by the  anaerobic decomposition of manure.   The low con-
centration at which these  compounds are  odorous  in air,  however,  frequent-
ly exceeds the sensitivity of existing analytical techniques.   Thus, ex-
tensive modification of traditional analytical techniques  is necessary.
Ammonia, hydrogen sulfide, mercaptans, and volatile organic acids have
been quantitatively measured in the air-volatilized material from manure
storage tanks.

Although certain odorous gases are known to  be toxic to  both humans and
livestock, the primary concern is one of annoyance or nuisance to humans.
Rules and regulations relative to livestock  odors are based primarily on
the concept of nuisance.  Whenever a neighboring property  owner feels the
odor from an animal production unit is unreasonably interfering with the
use and enjoyment of his property, he has the right to initiate legal
action to recover damages  or to seek an  injunction to halt or modify an
operation.  Both private and public nuisance suits have  been heard in the
last five years.  In some  of these cases the judgments have involved major
expenses for the livestock producer and, in  a few instances, required that
a producer cease operation or move to a more appropriate location.

Ammonia has been the most  widely studied odorous gas being evolved by
anaerobic manure decomposition.  The evolution of ammonia is of interest
not only because of its odor but also because the potential for reabsorp-
tion by nearby water bodies would lead to the possibility of aquatic en-
richment.  The atmosphere  near livestock production units has been mea-
sured in enough locations  to demonstrate a significant increase in ammonia
concentrations in these areas compared to residential or other agricultural
areas.  The volatilization rate of ammonia is a function of temperature,
pH and ammonia content of the material from which it would escape.

Scattered observations have suggested that the odor of manure can be in-
fluenced by changing the feed ration of an animal.  Sufficient data have
been gathered to indicate  this is a feasible approach, yet not enough work
has been  done for this to be considered a viable odor control technique.

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Various chemical treatments have been explored for reducing the odor of
stored animal manure.  Chlorine, lime, potassium permanganate, hydrogen
peroxide and paraformaldehyde have been applied to manure for their char-
acteristics of inhibiting anaerobic bacterial activity and their reaction
with known odorous compounds.  These chemicals have been demonstrated to
be temporarily effective when added in sufficient concentration.  There
are several proprietary odor control chemicals being sold for odor reduc-
tion or masking.  Their performance has received only limited study and
the published results are highly variable.

Soil columns have been studied as a means of removing odorous compounds
from air.  Their performance under laboratory conditions has been encour-
aging but they have not been applied to production facilities.

Although complete odor elimination around a livestock operation is not
currently within technical  and economic limits, there are several prin-
ciples  that have been proposed to minimize odor complaints.

 (a)  Locate a  livestock  operation such that close proximity  to residential
     areas is  avoided.   Although no maximum distances have been established
     beyond which complaints are not valid, it is desirable  to stay away
      from an urban area,  1600 m  (one mile) from housing  developments and 800 m
      (1/2 mile) from neighboring residences.  Wind direction and topography
      are of some importance in most areas.  However, in  some areas there is
     sufficient fluctuation in wind direction to make this factor of little
     help.

 (b)   Feeding areas and animal pens should be kept dry.   The  primary source
      of odor from a  livestock operation is that of anaerobic manure decompo-
      sition.   By keeping manure-covered surfaces dry, this decomposition can
     be minimized.   This same procedure not only is helpful  as  an odor con-
      trol scheme, but also  is beneficial  in the control  of water pollution
      due  to  runoff and is an aid in fly and insect control.

 (c)  Manure-management systems should be  designed to prevent dirty, manure-
      covered animals.  The  warm body  of an animal, when  covered with wet

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     manure,  makes  an area of  accelerated bacterial growth and odor produc-
     tion.   Once produced, the odorous by-products of manure decomposition
     are quickly vaporized into the  air by  animal heat.

(d)   Appropriate selection of  manure storage  and treatment devices can be
     helpful.  The  use of  aerobic systems in  general will reduce odor pro-
     duction.  Other measures  to inhibit anaerobic decomposition such as
     dry manure storage, chlorine or lime addition, or a cold storage sys-
     tem will reduce odorous gas production.

(e)   An orderly scheme of  runoff collection and manure handling not only
     avoids opportunity for water pollution but also promotes better drain-
     age, thus minimizing  areas of odor production.  In addition, an orderly
     appearing operation is effective in suggesting a non-offensive situa-
     tion.

(f)   Dead animal disposal  requires a definite plan  to avoid odors, flies,
     and severe health risks.   Prompt handling, with removal from the site
     within 24 hours, is required in most areas.  Pickup by rendering
     works  is the preferred disposal method where quickly available; other-
     wise,  burial or incineration may be considered.

(g)   Odor control chemicals have achieved limited use in livestock opera-
     tions.  Because of the lack of  an effective means of evaluating the
     performance of these  materials  and  their expense, odor control chemi-
     cal use has been generally limited  to  short-term applications or use
     only in particularly  offensive  areas,  such as  a manure-storage pit
     immediately before hauling.

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                                    SECTION I

                     INTRODUCTION TO ODOR CAUSES AND CONTROL

Odors associated with livestock production are generally related to
manure handling but other potential odor sources exist.  Wet feed, if
not promptly removed, makes a contribution to odors as does the decom-
position of dead animals if they do not receive proper handling.  Ani-
mal feeds also have various odors as they are stored and handled before
feeding and as they are fed.  However, feed odors are not generally re-
garded as offensive as those from the decomposition of manure.

Manure is a complex mixture of carbohydrates, fats, proteins and  their
breakdown products.  When manure is in a suitable environmental condition
during handling, it serves  as a substrate for biological growth.  This
biological growth  utilizes  the manure as an energy source and yields one
of  the next succeeding  compounds along the metabolic chain.  Examples
of  the biological  transformations occurring in manure  are shown in Figures
1,  2  and  3.  When  manure undergoing decomposition has  a surface exposed
to  the  atmosphere, volatile products  and intermediates will tend  to es-
cape  into the  atmosphere.   This is  the source of odorous gases  and vapors.

One method of  avoiding  odors is to  prevent the  formation of odorous break-
down  products.  Although frequently difficult or even  impossible  to accom-
plish in  practice, the  principle is straightforward:   Maintain  the manure
in  an environment  unsuitable for the  growth  of  anaerobic microorganisms.
This  can  be  done by:   (a)   providing  an aerobic environment,  (b)  maintaining
the moisture  content  so low that growth is inhibited,  (c) controling the
pH  so that growth  is  inhibited,  (d) adjusting the  temperature outside  the
 region  of bacterial  growth, (e) adding a chemical which inhibits  biologi-
 cal growth,  or (f) by changing  the  microbial population so  the  formation
of  specific  compounds is avoided.

Although  difficult as a means  to achieve total  odor  control,  each of  the
 above restrictions on microbial  growth has been investigated.   Each has

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    Ammonia

      NH,,
                 Proteins
                     I
                 Proteoses
                     ;
                 Peptides
                     1
                 Amino Acids
                H

             [R- C  -COOH]
             Hydroxy Acid    [R- C -COOH]
i
                                 OH
                                                             H
                                Volatile  Organic Acid    [R- C -COOH|
                                                             H
                Figure 1.   Anaerobic breakdown of proteins
R
i
                            R
  H- C -NH  + C =0   	»

     COOH     R      EaZyme
Amino Acid   Ketone
     R          R
     i           I
     C =0 + H-  C -NH,
                                            i
                                            COOH

                                            Keto
                                            Acid
                                   H

                                 Amine
                    Figure 2.  Bacterial transamination


                              Polysaccharide
                                    i
                               Disaccharide
                                    i
                                  Hexose
                                    i
                               Pyruvic Acid
AEROBIC CONDITIONS
           Carbon Dioxide
                    Water
                             ^  ANAEROBIC CONDITIONS
                              Acids
                              Aldehydes
                              Alcohols
                              Re tones
                              Carbon Dioxide
                              Methane
              Figure  3.  Pathways  of  carbohydrate decomposition

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specific limitations either in. terms of technology or cost.  However,
most are finding application in the control of manure odors as is indi-
cated in Table 1.

Table 1.  USE OF RESTRICTIVE ENVIRONMENTS TO CONTROL THE FORMATION OF
          MANURE ODORS BY ANAEROBIC DECOMPOSITION

  Technique                    Application                 Limitation

  Aerobic environment          Oxidation ditch           Power and equip-
                               Aerated lagoon              ment costs
  Moisture control             Manure dryers             Manure transport
                               Power ventilated poul-    Control of water
                                 try manure pits           leaks
  pH adjustment                Lime application          Ammonia release,
                                                           cost, solids
                                                           increase
  Temperature                  Freezing                  Cost-handling
  Chemical inhibition          Chlorination              Cost
  Microbial population         Digestive aids            Technology
    adjustment
 Considerable work has been done  to  determine  the  characteristics of animal
 manures  as produced by the specific animal.   Summaries of these character-
 istics are included in Tables 2  and 3.  Animal waste characteristics have
 been  determined primarily for use in  assessing water pollution effects or
 the parameters for liquid waste  handling.  Little attention has been given
 to analysis of these waste products specifically  oriented toward odor pro-
 duction  and control.

 The odor of fresh manure can be  intuitively assumed to be a function of
 the animal specie, the feed ration  being consumed, and the existing micro-
 floral population within the animal intestine.  Within these variables
 would be included the absence or presence of  intestinal  diseases and spe-
 cific metabolic disorders of the animal as well as environmental stresses
 which might be influential in changing the animal's feed utilization.
 These considerations suggest that there may be great variation in  the
                                       7

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volatile compounds present within manures from a specific specie.   After
being voided by the animal, the manure's further decomposition will be
influenced by the environment in which it is maintained.   At this  point,
another opportunity for odor control exists.  Variables which offer some
potential control are moisture condition, dissolved oxygen level,  and
specific biological controls which might be used to alter the course of
decomposition.  For any specific metabolic process, other potential means
of varying the odor release pertain to the control of volatilization of
the odorous compounds, the amount of dilution which occurs, and the proxim-
ity of the odor source to the potentially offended persons.
Table 2.  CHARACTERISTICS OF FARM ANIMAL MANURES PER THOUSAND LIVE WEIGHT
          UNITS PER YEAR (POUNDS OR KILOGRAMS)2
Animal
Dairy
Beef
Poultry
Swine
Sheep
N
131
170
262
147
123
P2°5
36.1
26.3
292
66
43
K
55.8
39.4
134
37
89
BOD5
1.7
1.5
4.0
2.1
0.7
Table  3.  DAILY MANURE PRODUCTION AND CHARACTERISTICS OF LIVESTOCK IN CON-
                                                                        3
          FINEMENT, PER THOUSAND LIVE WEIGHT UNITS  (POUNDS OR KILOGRAMS)

Raw manure (RM)
Total solids (TS)
Total solids, percent RM
Volatile solids (VS)
Volatile solids, percent TS
BOD
BOD,., percent VS
BOD^, percent COD
Nitrogen, percent TS
Phosphoric acid, percent TS
Potassium, percent TS
Dairy
88
9.0
10.0
7.2
80
1.7
24
16
4.0
1.1
1.7
Beef
60
6.0
10.0
4.8
80
1.5
31
17
7.8
1.2
1.8
Hens
59.0
17.4
30.0
12.9
74
4.4
34
28
5.7
4.6
2.1
Pigs
50
7.2
14.4
5.9
82
2.1
35
33
5.6
2.5
1.4
Sheep
37
8.4
22.7
6.9
82
0.7
10
8
4.0
1.4
2.9

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                                  SECTION II


                          HUMAN RESPONSE TO ODORANTS


Although certain odorous gases are known to be harmful and toxic, the

principal effect upon humans is one of annoyance or discomfort.   The

phenomenon of toxicity, although important in the area of industrial hy-

giene and overall human health, is not generally the problem with respect

to livestock waste odors.  Specific human health hazards associated with

gases which evolved from animal waste are limited to situations in which

persons encounter large concentrations of such gases.  Particularly haz-

ardous are instances where people enter manure storage tanks without

adequate ventilation or situations in which explosive mixtures of meth-

ane have been captured within a building and then ignited.


Several gases identified in livestock manure odors are of concern in
atmospheres in  an industrial setting where people might work.  Table 4

lists several gases which may be encountered in an odorous environment

and the concentrations which are considered not to be hazardous to human

health or safety.


Table 4.  CHARACTERISTICS AND PERCEPTIBLE CONCENTRATIONS OF VARIOUS SUB-

          STANCES IN AIR

                                                        Concentration
                                   _,                 causing faint odor
                                   Odor                     6_9
  Substance                    Characteristic               10  g/1

  Acetaldehyde                 Pungent                        4
  Ammonia                      Sharp, pungent                37
  n-Butyl mercaptan            Strong, unpleasant             1.4
  Carbon disulfide             Aromatic odor, slightly        2.6
                                pungent
  Ethyl mercaptan              Odor of decayed cabbage        0.19
  Hydrogen sulfide             Odor of rotten eggs,           1.1
                                nauseating
  Methyl mercaptan             Odor of decayed cabbage        1.1
                                or onions
  Propionaldehyde              Acrid, irritating odor         2
  Propyl mercaptan             Unpleasant odor                0.075

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Ammonia has been one of the gases associated with livestock wastes  of
greatest interest to both researchers and livestock producers.   It  is
produced in relatively large quantities by the anaerobic decomposition
of proteinaceous material and by the breakdown of urea.   Ammonia has a
distinctive odor discernible by most observers at concentrations of ap-
                      4
proximately 0.037 mg/1  or 30 ppm by volume.  Other researchers have re-
ported ammonia threshold odors of 46.8 ppm.   One complication is that
ammonia is seldom encountered independently of other odorous compounds.
Several other compounds, particularly the amines, have odor qualities
quite similar to ammonia, but are detectable at much lower concentra-
tions.  At concentrations of approximately 0.3 - 0.5 mg/1, ammonia acts
as an irritant to the eye, nose  and throat of humans.  At high concen-
trations it acts as an asphyxiant.   Similar reactions have been noted
in domestic animals with the additional observation that at even low
concentration ammonia tends to interfere with the action of the cilia
of the upper respiratory tract.

Hydrogen sulfide has been of concern relative to livestock wastes because
of its toxicity to both humans and animals as well as its objectionable
odor.  Concentrations in excess  of 400 ppm have been toxic to man.    Sim-
ilar  levels also are responsible for livestock deaths.  Hydrogen sulfide
poisoning  of animals has always  been associated with some event such as
agitating  a manure storage  tank  which  caused the H S level to rise up to
1000  ppm  for a  short period.  Chronic  H S  poisoning is not a problem be-
cause it  is rapidly oxidized to  sulfate in the blood.

The most  common complaint relative to  livestock  production is that of
odor.  Table 5  lists several gases associated with  animal waste odors
and their  perceptible,  threshold concentrations.  An odor may be inter-
mittent, the usual case, or in certain instances may be  continuous.  Per-
sons  living near  livestock  production  facilities are protected under the
law by the concept of nuisance.   A nuisance  in  the  legal sense may be
summarized as anything which causes  an unreasonable interference with
the use and enjoyment of property.   The various  aspects  of nuisance  rel-
                                                                      Q
ative to  livestock production were treated in some  detail  by Paulson.

                                        10

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Table 5.  THRESHOLD LIMIT VALUES* FOR VARIOUS GASES ASSOCIATED WITH ANI-
          MAL WASTE ODORS
                                                     ———  .   —
             Substance                          Concentration 10   g/1
           Acetaldehyde                                 360
           Acetic acid                                   25
           Ammonia                                       35
           n-Butyl acetate                              710
           Butyl mercaptan                               35
           Diethylamine                                  75
           Dimethylamlne                                 18
           Ethylamine                                    18
           Ethyl mercaptan                               25
           Isopropylamine                                12
           Methylamine                                   12
           Methyl mercaptan                              20
           Triethylamine                                100

 *The Threshold Limit  Values  refer  to  airborne  concentrations under which
  it  is  believed  that  nearly  all  workers may  be repeatedly  exposed with-
  out adverse effect.

 DOCTRINE OF  NUISANCE

 Ownership of land  includes the right  to  impregnate  the air with odors,
 dust and smoke,  pollute  the  water  and make noises,  provided these actions
 do not  substantially  interfere with the  comfort of  others  or injure  the
 use and enjoyment  of  their property.   Whenever a person uses his land  in
 such a way as to violate  this principle,  he  may be  guilty  of maintaining
 a nuisance.   Thus,  the  doctrine  of nuisance  acts  as a restriction on the
 right of an  owner  to  use  his property as  he  pleases and is applied to  a
 series  of wrongs which may arise from an  unreasonable, unwarranted or
 unlawful use of  his property which produces  annoyances, inconveniences,
 discomfort or hurt that  the  law  will  presume to be  a damage.   What con-
 stitutes a nuisance in  a particular case  must be decided  upon  the  facts
 and circumstances  of  that instance.
                                        11

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Nuisance has been classified as either public or private.   A nuisance
is said to be public when the public at large or some considerable por-
tion of it is affected or when the act is done in violation of law.
When a public nuisance is involved, legal action may be brought by a
public official.  A private nuisance generally affects only one person
or a specific number of persons and it is a ground for a civil proceed-
ing only.  In most cases, livestock odor conflicts have been of this
latter type.

The fact that a business is carried on carefully and in accordance with
the ordinary methods employed in that business does not relieve the own-
er or person responsible from liability to a neighbor if that business
causing the nuisance is unreasonable and constitutes a nuisance.  Paulson
states that a livestock feeding operation, in itself lawful, is not a
nuisance per se.  When it interferes with another's use and enjoyment
of property or  injures that property, it may become a nuisance by virtue
of the way it is maintained or operated.  The precise degree of discom-
fort that must  be produced to constitute a nuisance must be decided upon
the basis of being reasonable or unreasonable.

For the odor of a livestock feeding operation to be considered a nuisance,
the stench must be offensive to the senses and materially interfere with
                                                      o
the comfortable enjoyment of property within the area.   It is not neces-
sary that the odors should be harmful or unwholesome.  It is sufficient
if they are offensive or produce such consequences, inconvenience or dis-
comfort as  to impair the comfortable enjoyment of property by persons of
ordinary sensibility.

A person who suffers damages or feels that he suffers damages because of
the odor of livestock operation has two courses of action open to him:
a suit for damages and a suit to enjoin or abate the nuisance and he may
                      Q
pursue either or both.   The remedies of injunction or abatement are gen-
erally considered by the courts as being harsh.  Normally only that part
of the operation which amounts to a nuisance will be abated or enjoined.
When the nuisance results only because of the method of operation or

                                       12

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manner in which the business is conducted, the decree will be formed only
to prevent that particular method or manner rather than prohibiting com-
pletely the use of the property by the person creating the nuisance.  It
is an essential element for injunctive relief that the annoyance or in-
jury be continuous or recurrent.  The use of premises which amounts to
a nuisance may be enjoined, however, if it reasonably appears that such
annoyances or injury will be recurrent.

To be liable for actual damages one need only create or commit a nuisance.
The party injured is normally allowed to show the best or most advanta-
geous use for which the property is to be used; this is then used as a
basis for determining the amount which would be adequate and fair compen-
        Q
sation.   Punitive damages are  allowed only when it can be shown that
one has created and persistently maintained a nuisance with a reckless
disregard for the rights of others or when he has reason to believe that
his act may injure another and  does it in deference to the rights of
others.  The mere commission of an act justifying an award of actual
damages is not sufficient  to justify the  award of punitive damages  as a
        Q
penalty.

Several court cases involving livestock production odors have been heard
in  recent years.  A limited number of these cases are listed in Appendix B.

The litigation experiences of five livestock and poultry producers were
summarized by Willrich  and Miner.    They listed the major causes of con-
flicts  that precipitated these  civil proceedings as follows:  noncompli-
ance with zoning regulations; offensive odors exhausted from totally en-
closed, mechanically ventilated buildings in which manure and waste feed
were  decomposing anaerobically; offensive odors released from anaerobic
lagoons; offensive odors originating from manure decomposing on open lot
surfaces; surface water pollution caused by runoff; or transport of man-
ure from open lots.  Other causes included objectionable noises, exces-
sive  flies and rodents, manure  spillage on a public highway and suspected
ground  water pollution.
                                       13

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The probability of a livestock or poultry producer becoming involved in
                                                                      10
court litigation can be minimized by heeding the following  suggestions.
(a)  The production unit and associated waste handling and disposal facili-
     ties must comply with zoning regulations and all other applicable
     water pollution control and environmental quality regulations.
(b)  Provide an adequate separation distance between odor source and the
     points where the odor could offend others unreasonably and thus con-
     stitute a nuisance.  Provide an adequate buffer zone for odor dissi-
     pation in all directions from the odor source,  not just in the pre-
     valing wind direction.
(c)  Use waste management methods that minimize release of offensive
     odors, particularly if the available buffer zone is inadequate for
     normal dissipation by natural conditions.
(d)  Use waste management methods that control the release of potential
     pollutants into the surface and underground waters and the produc-
     tion of flies, rodents, and other pests.
(e)  Avoid or otherwise screen or isolate from public view any unsight-
     liness that might suggest the productional facility could be a
     source of odor, flies, or other causes of nuisance or material that
     could cause environmental quality degradation.
(f)  Practice the negative golden rule.  Don't do to others as you would
     not like them to do to you.
                                      14

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                                  SECTION III

                          ANIMAL RESPONSE TO ODORANTS

Because of the difficulties in measuring the strength of odors,  no data
correlating odors to animal response exists.  There has been,  however,
considerable work reported which establishes the deleterious effects of
air pollutants on the health and performance of livestock.   This sub-
ject was reviewed in great detail by Lillie.   The material which follows
will deal only with those gases and vapors associated with livestock pro-
duction and their effect on animals.

AMMONIA

Ammonia in the atmosphere at levels tolerated by man (less than 25 ppm
              3
or 17 mg per m ) does not constitute an air pollution crisis to domestic
animals.   Higher levels created by poultry kept under poor management
practices have been known to produce an eye disorder known as keratocon-
junctivitis and to affect the overall performance of poultry, especially
with high temperature and high relative humidity.  Avian leukosis was
not influenced by ammonia.  High levels of nutrition counteracted the
detrimental effects of ammonia as did proper management and ventilation
practices.

A study, conducted by Charles and Payne,   indicated that at 18  C and
at 67 percent relative humidity the use of atmospheres containing 105 ppm
of ammonia (by volume) significantly reduced egg production after 10-weeks
exposure.  No effects were observed on egg quality.  When White Leghorn
hens were housed at an environmental temperature of 28  C, body weight
decreased.  The decrease in live weight was greatest at the high ammonia
concentration of 102 ppm and was significant after only one week exposure
to the ammonia.  Exposure to ammonia further reduced the food intake of
the animal as compared to those housed in a low ammonia environment.  In
a subsequent trial, a high protein, vitamin and mineral diet prevented
the onset of harmful effects of ammonia on egg production, even though
food consumption fell significantly.
                                       15

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Duroc pigs were subjected to four levels of ammonia air contamination
(approximately 10, 50, 100 and 150 ppm by volume) in a study by Stom-
                         12
baugh, league and Roller.    The trials were conducted under environmental
conditions of 21.2  C temperature and 77 percent relative humidity.
Ammonia concentrations had a highly significant adverse effect upon  feed
consumption and average daily gain.  However, there was no significant
effect upon efficiency of feed conversion.

                                                        12
Preceeding the first trial, Stombaugh, Teague and Roller   placed a 30 kilo-
gram (66 pound) gilt in an ammonia concentration of approximately 280 ppm
for 36 hours.  When first placed in the compartment, frothing of the mouth
was observed and there were excessive secretions around the nose and mouth.
After approximately three hours, the frothing disappeared.  Excessive secre-
tion around the nose and mouth, a short and irregular respiratory pattern,
occasional sneezing, and occasional shaking of the head persisted.  After
36 hours in this environment, convulsions occured and breathing was  extremely
short and irregular.  At that point the ammonia supply was turned off, and
the compartment completely ventilated.  Although the pig continued to have
convulsions for at least three hours, its condition improved.  Seven hours
after convulsions ceased, except for occasional sneezing and shaking of
the head, the animal appeared completely normal.  This experience indicated
that an ammonia concentration of 280 ppm was too high to be used in  their
experiments.

HYDROGEN SULFIDE

Hydrogen sulfide is a highly lethal gas to man and  to livestock.  Incidents
of animal deaths attributable to hydrogen sulfide toxicity have been re-
ported, particularly when manure storage tanks beneath slotted floors have
been agitated prior to pumping to a tank truck or an irrigation system.
Lillie  provides documentation of three instances in which swine were killed
while manure storage tanks were being agitated.  Measurements have been
taken indicating that hydrogen sulfide concentrations after a brief period
of agitation can reach concentration in excess of 1,000 ppm which is well
over the 500 ppm level considered toxic to humans.
                                        16

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MIXED AIR POLLUTANTS

The effect of a manure storage tank located beneath and vented to an ani-
mal confinement facility is to increase the concentration of hydrogen sul-
fide, ammonia, carbon dioxide and methane within the atmosphere.  Agitation
of the liquid manure slurry results in a rapid increase of H S and CCL gases
above the levels at which they are normally toxic to livestock.  The clini-
cal symptoms of these gas toxicities are:  (a)  methane becomes explosive
in concentrations of five to six percent; (b) CO- produces palpitation at
the 10 percent level and a narcotic action that often results in death at
the 25 percent level; (c) ammonia causes irritation of eyes and respiratory
mucous  membranes at the 0.01 percent level and becomes a health hazard
at a level of 0.05 percent; (d) concentrations of 0.002 to 0.01 percent
H,,S irritates the eyes and produces dizziness within 30 minutes, a 0.05
percent level affects the nervous system and death occurs after 30 min-
utes of inhalation, and  inhalation of air containing 0.09 to 0.1 percent
H,,S produces  instantaneous death.
                                        17

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                                   SECTION IV

                            THEORY OF ODOR PERCEPTION

Each of the five senses is used to bring us information about our environ-
ment.  The ability to touch, taste, hear, see and smell brings us into
contact with our external world in such a way as to give us a better under-
standing of its status and changes.  The response to these senses is essen-
tially a personal reaction.  Whether a sound is pleasant, a feel is satis-
fying, a taste is enjoyable, a scene is beautiful, or a smell is desirable
is essentially a personal response based upon our cultural background and
our individual disposition of the moment.

The senses of touch, taste, hearing and sight all measure environmental
parameters which are also measurable by other techniques as shown in Table 6.
The sense of smell is unique in that no mechanical or chemical alternative
device exists for measuring the odor.  Thus, odor is essentially a subjec-
tive phenomenon for which no quantitative standard of comparison exists.

The human nose is the basic detector in odor analysis.  It may be supple-
mented in some cases by other instruments, but there is no replacement for
it even  though the complexities of its functioning are not thoroughly under-
       13        14
stood.    Moulton   stated that the final approach in odor and flavor identi-
fication is "a bioassay based on stimulation of the human nose.  But the
behavioral response of a man is not a simple objective index of olfactory
sensitivity.  It is the end product of a complex flow of interacting events,
molded by the needs and experiences of the individual—by the input of many
classes  of information.  Yet, in the last analysis, there is no adequate
substitute."

Measurement of odor intensity and  quality must be preceeded by an understand-
ing  of the way the nose functions  to distinguish one odor from thousands of
others.  A simplified sketch of the odor sensation process follows.  Infor-
mation of greater detail may be found in The Chemical Senses by Moncrieff.
                                         19

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Table 6.  THE HUMAN SENSES, EXAMPLES OF PARAMETERS MEASURED AND ALTERNATE
          INFORMATION SOURCES
  Sense
Parameter measured
Alternate device
Unit of measurement
  Sight     Color, intensity
  Sound     Pitch, intensity
  Taste     Saltiness, sour
  Touch     Temperature,
             hardness
  Smell     Odor
                       Colorimeter, light   Wave length,  lumens
                        meter
                       Tuning fork,         Frequency,  decibels
                        microphones
                       Chemical titration   mg/1, pH unit
                        pH
                       Thermometer
                       None
                     Degree
                     None
Figure 4 depicts the nasal cavity in the human head.  Inspired air typically
travels into the nostrils, through the turbinate area and down the throat
to the lungs.  Normal breathing will cause only a small portion of the air
to reach the olfactory  cleft and the olfactory nerves, located high in
the nasal cavity.  A "sniff", characterized by a short burst of air inspired
at a rate greater  than normal breathing, brings about extensive turbulence
and diffusion  to all parts of the cavity.  Odor sensation is much more ob-
vious from a concerted sniff than from the normal breathing rate.

The olfactory  nerve cells, shown in Figure 5, are located in the olfactory
cleft area.  The total olfactory reception area in the adult human is about
two square inches.  The olfactory cells are long and narrow; they are or-
iented perpendicular to the surface of the receptor area.  The cells are
pigmented yellow or yellow-brown.  On the exposed end of the nerve cells
are five to eight  olfactory hairs which extend into or through a mucous
layer which coats  the surface of the mucous membrane.  Surrounding the ol-
factory cells  in the mucous membrane are the sustentacular cells which
support and insulate the nerve cells.  Axons, originating at each nerve cell,
pass through the membrane at the base of the mucous layer and carry a mes-
sage to the glomeruli.

It is believed that the olfactory hairs are the means of reception of the
"signal" of the odorous molecule.  A chain of events follows which instan-
taneously gives odor perception.  The hairs are kept moist by the mucous  .,
                                      20

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OLFACTORY
   CLEFT
NOSTRILS
                                                      SPINAL CORD
                       Figure 4.  Human nasal cavity
SUSTENTACULAR
        CELL
BASEMENT
  MEMBRANE
                                                         HAIRS
                                                      RECEPTOR CELL
                                                  AXON FIBER
                        Figure 5.   Olfactory mucosa
                                      2 i

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layer.  An excess of the mucus as in the case of a head cold can incapaci-
tate the hairs and the sense of smell.  There are different kinds of odor
receptor cells—cells that respond to different odor stimuli.

Moncrieff   describes the mechanism of olfaction in six stages:
(a)  The molecules of a volatile substance are continually lost  to the
     atmosphere.
(b)  Some of the molecules, inspired with air into the nasal cavity, are
     directed to the olfactory receptors.  The aid of a sniff is benefi-
     cial but not essential.
(c)  The odorous molecules are adsorbed on appropriate sites on the olfac-
     tory nerve cells.
(d)  The adsorption is accompanied by an energy change.
(e)  An electric impulse, generated by the energy change, travels from the
     olfactory receptor to the brain.
(f)  The brain processes the information and transmits the sensation of
     smell.

MECHANISMS OF PERCEPTION

A precise relationship between chemical composition and odor would make
it possible to predict accurately the odor of an unknown compound or to
formulate a compound with a required odor.  Recent findings have shown
that odor is closely associated with molecular configuration, and this,
according to Moncrieff   is only half the story of odor perception.  The
other half consists of the receptor system and the brain of the person
doing the smelling.

An acceptable odor theory must account for odor phenomena.  Some of these
are listed here:
(a)  Only volatile substances are odorous.
(b)  Air movement into the nasal cavity is necessary to feed the receptors,
(c)  If air movement in the nasal cavity stops, odor sensation vanishes.
(d)  Water, though having the characteristics of other odorants, has no
     odor.
                                       22

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(e)   Gases  such as  oxygen and nitrogen have no odor.
(f)   Exposure to an odor produces  a high initial response and a declining
     response with  continued contact.   (Adaptation).
(g)   A strong odorant completely exhausts the capacity to perceive the odor
     in two to three minutes.  (Fatigue).
(h)   A change in odor sometimes occurs on dilution of the odorant.
(i)   Some animals have a better developed sense of smell than humans.
(j)   Isomers (having the same chemical composition)  have widely differing
     smells.
(k)   Compounds having widely differing chemical compositions have similar
     smells.
(1)   Some odorants  are perceived at a concentration of one millionth that
     of others.

The theories of odor perception differ essentially on the method by which
the "message" of the odorant is transmitted to the olfactory nerve.  The
primary theories have proposed  (a) chemical reaction, (b) physical adsorp-
tion and (c) molecular vibration as the cause of initial stimulus.

The chemical theory  can be  largely discounted on the basis of work done
on a freshly severed sheep's head.    An odorant was passed through the
nasal  cavity of  the  head and collected  and  analyzed after passage.  The
first  collection of  air which had carried the odorant into the sheep's
head contained none  of the  odorant.   (The odorant had been adsorbed onto
the receptor  cells  in the head.)  After a short time, the air passing
through  the head contained  a concentration  of odorant equal to that enter-
ing.   (The receptor  sites had been saturated and any particles adsorbed
only replaced  particles desorbed.)  The odorant supply was cutoff and the
airstream  continued  to circulate through the nasal cavity until no odorant
was detected  in the  exit air.   (The only odorant remaining in the head was
adsorbed onto  the  receptor  areas.)  After a period of time, up to several
hours, the air flow  was  again  started.   No  odorant was added.  The dis-
charged air again  contained the odorant in  its  original  form.   (The odor-
ant  desorbed  from  the receptor  sites  was unchanged.  No  chemical  action
had  taken  place.   The process  of adsorption is  essential in odor  perception.)

                                        23

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Events  in this  experiment are not, however, supported by the contention
of Davies   that particle retention time on the receptor surface is on
                —8
the  order of 10  seconds and that a chemical reaction not dependent on
the  reactivity  of the odor molecule occurs.

                                   18
The  stereochemical theory of Amoore   was first introduced in 1952.  This
theory  was based upon a fit between an odor molecule and a "socket" at
the  receptor site in the nose.  Seven types of receptor sites were pro-
posed to  serve  the seven primary odors—ethereal, camphoraceous, musky,
floral, pepperminty, pungent and putrid.  Other odors resulted from combina-
tions of  the primary odors.  Amoore has more recently altered his theory
to account for  a two-dimensional fit rather than three-dimensional.
Molecular silhouette or cross-sectional area is the important steric
                              19
characteristic  of the odorant.    Odor perception is initiated by an
energy  change brought about by the adsorption of the odorant molecule
on the  olfactory nerve.

                                                                   20
The  vibrational theory for human olfaction was introduced by Dyson.
The  theory proposed that odorous substances possess intra-molecular vi-
brations  of such periods as to produce Raman shifts between 1400 and
3500 cm"1.

                                                 21 22
Since 1954, the idea has been furthered by Wright   '   who suggests
that the  Raman  shifts of odorous substances occur at frequencies less
than 700  cm  .  It is the vibrations of this range that are most likely
to be active at body temperature.  The vibrational theory concludes that
odorant molecules have "odor-active" molecular vibrations which are best
evaluated by both the Raman and infra-red spectroscopy.  These important
vibration frequencies "fit" specific receptor sites in the nose (along
with a  steric fit) thus providing the initial stimulus for odor perception.

                 23
Davies  and Taylor   presented the penetration theory.  Odor perception
according to this theory depends upon two basic parameters:
(a)  The  partition coefficient of the substance between air and a water-
     oil  interface.  This relates to the adsorption-desorption properties
     of the odorant on the receptor site.
                                       24

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(b)   The cross-sectional area of the molecule.   This  relates  to  the
     characteristics of the puncture of the olfactory nerve by the odor-
     ant adsorbing on the receptor site.

Odor reception is initiated when the molecule adsorbs onto the olfactory
nerve causing a puncture of the surface lipoid membrane.  Residence  time
                                                           —A
of the odorant substance on the nerve is on the order of 10   seconds.
The time required for the puncture to heal is longer—on the order of
10   seconds.  In the interval between  desorption and healing of the
puncture an exchange of Na  and K  ions occurs.  This exchange,  brought
about by an excess of Na+ on  the exterior  and K  on the interior of the
membrane, is the stimulus for the olfactory perception process.   More
                                                           24
recent work on the penetration  theory by Theimer and Davies   has added
a third parameter for odor  dependence—the length to breadth  dimension
ratio of the molecule.

These theories are  the basis  for most  of the research related to olfactory
perception in recent years.   Two points of agreement  exist in these theor-
ies:   (a) the process is  initiated  with the  adsorption  of  the odorant
molecule on  the  olfactory nerve and (b) the  cross-sectional  properties
of  the molecule  are  a  controlling  factor.  Again, the primary difference
is  the manner by which  the  characteristic  odor of the molecule  is trans-
lated  to the olfactory  nerve.  It  is feasible  that  all  of  these theories
might  be involved in the actual odor perception reaction.

 Finally, the odorant substance must possess  certain characteristics  if
 it  is  to be  subject to the theories presented:  (a)  the substance must
 be  sufficiently  volatile that molecules can be transported to the nasal
 orifices;  (b)  solubility in the lipoid material of  the  mucous membrane
 is  essential.   Solubility in water is helpful; and  (c)  the odorous  sub-
 stance must  be able to be adsorbed onto the sensory nerve.

 ODOR STRENGTH

 Accurate characterization of an odor includes reference to its  strength,
 or intensity, and its quality. American Society for Testing and Materials,
                                        25

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                                    25
"Manual  on  Sensory Testing Methods,"   effectively describes the ground
rules  for conducting odor strength and quality tests.  The manual states
the  requirements  for the physical facilities, the test subjects and the
samples  to  be tested.  The kinds of tests that may be applied are dis-
cussed along with procedures for analysis of the data.  The manual does
not, however, describe the detailed procedure by which the individual
tests  must  be conducted.  Such details are dictated by the kind of mater-
ial  and  the characteristic of the odorant being judged.

The most common method of measuring odor intensity is by dilution to
extinction.   The odorant is diluted with an odor-free medium until its
odor can no longer be detected.  The greatest dilution at which the odor-
                                                                   9fi
ant is just barely detectable is termed the threshold value.  Baker
compared four common procedures for determining the threshold value of
an odorant  in odor-free water dilution:
(a)  Standard Method, STD; five flasks containing serial dilutions plus
     one "catch trial" blank.
(b)  Consistent Series, CS; five flasks containing serial dilutions plus
     two blanks.
(c)  Triangle Test,  TT; three flasks at each dilution level, two of which
     are blank.
(d)  Short  Parallel, SP; two flasks at each dilution level, one of which
     is  blank.

The tests were run using two odorants, n-butanol and m-cresol.  The re-
sults  showed that the tests in order of decreasing sensitivity were TT,
CS, SP and  STD.  Baker, however, points out that no test is obviously
superior when performed under controlled conditions with trained person-
                         27
nel.  Burnett and Dondero   reported on a modified procedure for threshold
odor determination.

Threshold odor levels are also measured using odor-free air as a carrier
and dilution medium.  Equipment for the air-dilution method is more intri-
cate and expensive,  but the results are more reliable as a measure of
true odor intensity.  A number of writers have reported on odor threshold
                                       26

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                                              15 27 28
determinations with the air dilution procedure.  *  '     Suprathreshold
odor intensities can be judged directly.  The odorous unknown is  compared
with a similar or like odorant of known intensity.   The observer  makes
                                                               29
an intensity judgment based on the comparison.  Jones and Waskow    and
     30
Stone   described methods to utilize this test practice.  Either  liquid
or air-dilution procedures may be used to make the comparisons.   Supra-
threshold odor-intensity judgments lack the reliability of the threshold
level determination.

Odor intensities are stated in terms of the odor intensity index, Oil, or
the threshold odor number, TON.  The two values are related according to
the equation
                               2011 = TON                      (1)
Oil is defined as the number of times an odorant must be diluted  by half
with odor-free medium until the threshold is reached.  TON is defined as
the greatest dilution of the odorant with odor-free medium until  the
threshold is reached.  Most writers seem to prefer to use Oil rather than
TON.  Certainly an Oil value of 15 is less cumbersome and easier  to grasp
than the equivalent TON value of 32,768.

Odor-intensity testing can be objective in nature if a sufficient number
of qualified, properly prepared observers are used and procedures and
conditions of the test are standardized.  Odor threshold measurements
are more objective than suprathreshold measurements.  ASTM   stated that
the minimum number of observers for any test is five since any fewer num-
ber places too much dependence on the response of any individual.  The
subjects must pass a preliminary screening to assure that they are capable
                                                                  31
of making a normal response to the stimuli to be presented.  Swets
emphasizes the need to inform the observer as fully as possible concern-
ing the nature of the judgments desired, the test procedure and the con-
trols to be employed.  Uncertainty plays a big role in reducing the
effectiveness of the subject and, consequently, the validity of the re-
sults.  Swets further suggests the inclusion of a large number of catch
trials (trials which contain no odorant) to insure the certainty  of a
positive decision.

                                      27

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ODOR QUALITY

Odor-quality references are often made by comparing the odor with an odor
that is  familiar.  The odor is "like coffee", "like new-mown hay" or
"like a  characteristic poultry odor".  The judgment of "characteristic
poultry" would depend on past experiences.  This recollection may result
from a light, well-ventilated house with little more than the smell of
must or  feed, or it may have been a highly populated house with poor ven-
tilation, high humidity and concentrated ammonia.  One's interpretation
could include a wide range of quality values.

Many attempts have been made to produce a list of basic odor classes that
would describe the qualities of all other odors.  These have been report-
                          14 15
ed by a  number of authors.  '    Five of these lists are presented in Ta-
ble 7.   Classes of similar qualities are placed on the same line.

Table 7.  BASIC ODOR QUALITY CLASSIFICATIONS AS DESCRIBED BY FIVE AUTHORS
15
Zwaardemaker
1895
Ambrosial
Balsamic or
fragrant
Ethereal
Aromatic

Empyreumatic
Alliaceous
Caprylic
Henning Crocker and
1916 Henderson, 1927

Flowery, Fragrant
resinous
Fruity
Spicy

Burnt Burnt
Foul
Caprylic
Amoore
1952
Musky
Floral
Ethereal
Camphora-
ceous
Minty



Davies
1965
Musky
Floral,
cedary
Ethereal,
fruity
alcoholic
Camphora-
ceous ,
aromatic
Pepper-
minty
Almond


Repulsive
Nauseating,
foetid


Acid
Putrid
Pungent


                                      28

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Qualitative odor testing is widely used in the food and perfume  indus-
tries.  Use of qualitative odor testing in livestock waste research is
limited.  The test is often made by comparing the unknown with a known
odorant of similar or dissimilar quality in paired comparisons.   The
observer then makes a judgment of the degree of similarity.

Odor-quality testing lacks the desired objectivity of the odor threshold
determinations.  Quality tests require observer judgments relative to a
known odorant and subjectivity is unavoidable.  To maximize the  validity
of the test, the preparations of the physical facilities, the samples,  and
                                25
the subjects as outlined by ASTM   are of utmost importance.

LIMITATIONS OF ODOR TESTING

The limitations of odor testing result from the existence of odor phenomena
and the preferences (or subjectivity) of the observers.  The sources of
these limitations will be  discussed  individually.  It should be apparent
how each limitation can enter into the interpretation of odor test results.

Adaptation
Adaptation  is the adjustment of the  observer  to the odor stimulus.  The
level of sensation diminishes with time even  though the stimulus is ap-
plied at a  steady rate.  Observers who enter  the vicinity of livestock
buildings or yards soon lose the  ability  to make unbiased odor  judgments
about odorants similar to  those of the immediate environment.   The rate
of adaptation varies with  the strength of  the stimulus.  Moncrieff   dem-
onstrated the effect of adaptation.  A subject who first took a sniff of
pure  acetone could recognize nothing less  than 5.0 percent  acetone with
a second sniff.   This is  170 times the threshold concentration.  The
effect  of a dissimilar odor was not  so great.  After smelling pure ace-
tone, n-butanol  could be  recognized  at 0.06  percent or  12  times the  threshold
concentration.

                                               2ft
Adaptation  effects were also  reported  by  Baker  who tested the influence
of light, background odor on odor-intensity  tests. Background  odor  simi-
lar  to  the  odorant  tested reduced the  Oil slightly while  a background  odor
                                       29

-------
dissimilar to the odorant tested produced a slight increase in the Oil.

Fatigue
Fatigue is the result of adaptation.  Exposure to a strong odorant may
completely exhaust the capability to sense the odor.  Fatigue develops
gradually, with an exposure of two to three minutes required for total
exhaustion.  Recovery after removal of the odorant requires about the
same length of time.  Fatigue is selective.  That is, fatigue to one
odor will reduce sensitivity to similar odors, but does not produce fa-
                     13
tigue for all odors.

Odorant concentration
Changes in odor quality sometimes occur due to dilution.  For example,
concentrated furfuryl mercaptan has a nauseating odor but is reminiscent
of the aroma of coffee when greatly diluted.  Moncrieff   theorized that
this effect may result from a substance comprised of more than one recog-
nizable odor where each odor has a different threshold.

Moncrieff   reported the concept of limiting intensity.  The concept
says that  the human  nose cannot distinguish between odorant concentra-
tions greater than a saturation level.  The reasoning behind the concept
(which heavily supports the adsorption theory of odor) is that the re-
ceptor sites become  filled with odorous molecules and an increase in the
number of molecules  inspired causes no increase in sensation.

Standard procedure for odor threshold testing utilizes serial dilution
with each succeeding dilution 50 percent of the one before.  Fractional

                                                                        .15
                                 26
dilution is not justified.  Baker   reported variability of about one
Oil unit with  the four threshold test procedures that he used.  Moncrieff
stated that an increase of about 30 percent in odorant concentration is
necessary to produce a perceptible sensation.

Both air and liquid dilution media are employed in odor testing.  The
liquid is usually odor-free water, but alcohol in combination with odor-
free water has been used when the odorant was not soluble in water.
                                       30

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Definition of the dilution system and other test conditions are important
                            28
in reporting results.  Sobel   stated that different threshold values
are obtained from air and water dilution methods for the same odorant.
An awareness of the significance of air and liquid dilution systems is
desirable.  A water dilution system dilutes the source of the odor until
the emitted odor is just detectable.  This measures the odor-producing
capacity of the odorant.  The air dilution system dilutes the odor pro-
duced until that odor can just be detected.  This measures the strength
of the odor produced by the odorant.  Both systems have application in
studying odor from livestock operations.

Mixtures
             32
Rosen  et al.   listed four possible  reactions  for mixtures of two in-
dividually odorous components.   In  these  equations, RA is the odor stimu-
lus of component A, R_. is the odor  stimulus of  component B, and R
                     a                                           *
the odor stimulus from the combination  of components  A and B.

(a)  Independence                 RA+B = RA °r ^B
(b)  Antagonism or                RA+B < RA °r
     counteraction
(c)  Addition                     RA+B = RA + ]
(d)  Synergism                    RA+B > RA •*

Work of Baker26 confirmed  examples  of additivity,  antagonism  and  synergism.

Jones  and Woskow29  tested  the  odor intensity  of two component mixtures
of odorants.  They  used  all  possible combinations  of three  similar odorants
and,  also,  of combinations  of  three dissimilar  odorants.   The  odor magni-
tude  of  the mixes was  not  additive, nor was  it  an  average  of  the  two com-
ponents.   The odor  level of  the combinations  was  somewhere  between the  sum
and the  average.  This reaction lies in a region not specified by the Rosen
       32
 et al.   reactions  	  RA+B < RA + ^B >  A    B  '
                                       31

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Moncrieff   described counteraction (the mutual discrimination) of two
odors to the exteat that they are odorless in combination.  Using low
concentrations of the odorants they tend to be additive, but with cer-
tain combinations of high concentration, the effect was no odor.  Guadagni
      33
et al.   found that the combination of sub-threshold concentrations of
odorous components produced suprathreshold mixtures.
Without prior  knowledge, the quantitative and qualitative outcome of the
reaction  of  the  combination of two components is unpredictable.  In addi-
tion,  the type of  reaction, according t<
to the concentration  of the components.
tion, the type of reaction, according to Moncrieff,   can vary according
Complex mixtures  of  odorants may not offer the same mysterious range of
reactions  offered by two-component systems.  Complex odorant mixtures
have  direct application to the field of livestock odors where odors often
                                                        33
result  from complex  biological systems.  Guadagni e_t^ ^3^.   in testing
complex systems of up to ten odorants concluded that the reactions were
mostly  additive rather than synergistic, antagonistic or independent.
This  would be the anticipated result for complex systems where the more
common  additive reaction outweighs the other somewhat unusual reactions.
In  this case, "additive type reaction" refers to one that is additive in
nature  and not strictly additive as in the reaction stated by Rosen.  The
interpretation is that (using the two-component reference notation)
                                    RAfB > RA
Temperature
The  recommended temperature for  comparative odor  testing  is  40   C.   This
temperature was preferred by panelists  as  compared  to  temperatures  of
21°  and  60° C.     The lower level produced "dead" samples while  the high-
er level produced some steaming  and gave fleeting initial responses
(probably due to the extensive removal  of the more  volatile  odorants
present).   An Oil increase of 1.4 units was noted in increasing  the di-
luted  odorant test samples from  21  to  60  C.

                                        32

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Other temperature levels for odor testing are reasonable where  odor in-
tensity and quality measurements are to be indicative of operative  con-
ditions different from 40° C.  The odor intensity determination for man-
ure stored under winter conditions might be made at 4  C, while odor levels
generated under summer or warm weather conditions might be reported at
20° C.  Where odor levels are established strictly for comparative  pur-
poses, the standard af 40° C would be desirable.

Anosmia and parosmia
Anosmia (odor-blindness) is a condition which affects about 10 percent of
the population.  Partial anosmia, anosmia for a group of similar odors,
is more common than complete anosmia.  Partial anosmia is much more like-
                                                          13
ly to exist without the knowledge of the afflicted person.

Parosmia  (perversion of odor) is  a  second type of olfactory disease.  The
parosmatic senses a different odor  than  the  one put before him.  The per-
verted odor is often an unpleasant  one.  The condition  is likely to be
          13
temporary.

Pungence
"Puneent" has been included  as  a basic odor  type by  some authors.   This
                                                                     18  22
odor is associated with strong  acidic  and basic  smells.   Two authors
proposed  that pungence may not, in  some cases,  be  a  true olfactory nerve
response, but a  sensation  of pain caused by  irritation of the  trigeminal
nerves  in the nasal  cavity.
 In general,  man's sense of smell develops until the age of about  20.   The
 good sense of smell continues until the age of about 50 and then  declines.
 Venstrom and Amoore   tested 97 normal subjects to determine the  rate
 of decline of olfactory sensitivity with age.   The study showed that man
 has a 50 percent reduction in the sense of smell in 22 years.   This com-
 pares with 13 years for a 50 percent reduction in sense of sight, 15 years
 for sound, 29 years for taste and 60 years for touch.
                                   33

-------
Moncrieff   related that children have a greater tolerance for a fecal
odor such as skatole.  He also states that man develops a taste for
partially-decomposed food such as aged meat and cheese as he grows older.
Children rank fruity odors highest for pleasantness while adults prefer
fragrant odors.

Sex.
Authors are divided on the theory that women are more sensitive, olfac-
torywise,  than men.  The case is well stated by the research of Venstrom
           34
and Amoore   who  found that women were about one-quarter Oil unit more
sensitive  to odor intensity than men but that this was not a significant
amount  for the conditions of their study.

Moncrieff   points out that men are more nearly unanimous in their pre-
ference fox pleasant odors while women are more unanimous in their selec-
tion  of odors which  are unpleasant.  Women as a group think culinary odors
are more pleasant than men do.

Smoking
Like  the battle  of the sexes, the question of sensitivity of smokers is
                                                   34
unsettled.  Again, the work of Venstrom and Amoore   gives a good picture
of the  facts by  reporting that non-smokers were about one-fifth Oil more
sensitive  to  odor intensity than were smokers but  that  this was not sig-
nificant for  the conditions of the test.  It is necessary, however, that
smokers refrain  from smoking  for  15 minutes before  the  odor test.

Natural variation
According  to  Moncrieff   olfactory capabilities among healthy  persons
are  fairly uniform.   The primary  difference  is  the form of  the nasal pass-
ages.   Additional variations,  though  slight, can  result from  any  of the
myriad  diseases  and conditions which  affect  the state  of the nasal  cavity
and  olfactory nervous  system.

SUPPLEMENTARY INSTRUMENTS
The  gas-liquid chromatograph,  GLC, has been the most important instru-
ment in supplementing  the capabilities of the  human nose in odor  research.
                                        34

-------
While the nose can best determine the quality and intensity of simple
and complex odor combinations, the GLC can best fractionate and quantify
the odorant components involved.  The capabilities of one do not replace
the capabilities of the other.  Advancing technology has made possible
increased sensitivity of the GLC and, therefore, greater capacity to
identify the trace quantities of odorants in complex materials.  A num-
ber of researchers have reported the use of the GLC for odor component
identification for livestock wastes.   '  '  '  '

                   39
Kendall and Neilson   compared the sensitivity of the GLC to the nose.
They found that their panelists could detect odorant concentrations 10
to 100 times more dilute than the GLC.  Other  types of chromatography,
though less sensitive, can  also be useful in component identification
after separation.

Odometers of various forms have been  developed to assist  in test work.
The meters are of the general form that can make  the necessary  dilutions
of the odorant with odor-free air prior to inspiration.  The meters have
been given such names as "osmoscope",  "odormeter" and "osmometer".  Des-
                                                               30
criptions and use of  these  instruments have been made by Stone   ,
         1 S           28
Moncrieff    and Sobel.

Development of a "mechanical  nose" which would eliminate errors of natural
variation and subjectivity  in the human nose would greatly advance odor
research.  The most  important obstacle in  such a  development must be  the
lack of  understanding of  the  odor perception process  of  the human nose.
Even so,  several researchers  have made efforts to duplicate the human
 nose.
 In 1961 Moncrieff   developed a mechanical nose.   Many refinements were
 added later.     The instrument utilizes a pair of matched thermistors,
 one of which has a thin protein film placed over it.   As an odorant passes
 over the thermistors, the unbalanced rates of adsorption on the protein
 film and the glass coating of the other thermistor cause a temperature
 differential.  A flow of current between the thermistors caused by the

                                      35

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                                                                    41
unequal resistances is measured on a micro-ammeter.  Friedman, et al.
adapted this type of mechanical nose for their work on energy changes
associated with odor perception.

                          42
In 1964, Rosano and Scheps   reported on their efforts to develop an
artificial nose.  These writers used an instrument which allowed simul-
taneous study of adsorption and chemical interaction.  Their contention
was that enzymatic action must be considered in the odor perception process.

These attempts to further understand the function of the human nose and
to simulate  it have met with some degree of success.  Some of the responses
of the machines closely resemble those of the nose.  It appears, however,
that the complexities of the human nose are impossible to duplicate.
                                        36

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                                   SECTION V

                       RELATIONSHIP BETWEEN ODOR AND pH

To exhibit its characteristic odor, an odorous substance  dissolved in
water, must escape from the liquid phase.  Ionized species have no vapor
pressure, thus, only the non-ionized species are effective in odor pro-
duction.  Hydrogen ion concentration is the single most important variable
in determining the fraction of a substance in the non-ionized form.  Us-
ing lime to control the escape, hydrogen sulfide is an applied example
of this phenomenon.

Quantification of this characteristic is best achieved by considering the
pK values.  At a pH equal to the pK, one-half of the compound is present
in the non-ionized form.  For acidic odorants, a decrease in the pH by one
unit causes the fraction of the non-ionized species to increase to 91 per-
cent.  Increasing pH values result in the opposite effect.  For basic
odorants, increasing pH values result in greater quantities being present
in the non-ionized fraction, thus in greater volatility.  Table 8 includes
a tabulation of pH values for various odorants at which the compound is
50 percent ionized.

Table 8.  pH VALUES FOR WHICH VARIOUS ODOROUS COMPOUNDS ARE 50 PERCENT
          IONIZED AT 25° C 3
Acidic Compounds
Acetic acid
Butyric acid
Hydrogen sulfide
Propionic acid







pH
4.75
4.83
7.04
4.87







Basic Compounds
Ammonia
n-Butylamine
Diethylamine
Dime thy 1 amine
Ethylamine
iso-Butylamine
iso-Propylamine
Methyl amine
Propylamine
Triethylamine
Trimethylamine
pH
9.25
3.39
3.00
3.30
3.33
3.58
3.37
3.36
3.42
3.28
4.20
                                        37

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                                  SECTION VI

                             DESORPTION OF AMMONIA

Although ammonia is highly soluble in water, an equilibrium exists be-
tween the ammonia concentration in water and its partial pressure in
air.  When manure or manure slurries, high in ammonia, are in contact
with air, desorption takes place.  The driving force is the partial pres-
sure of ammonia in equilibrium with the liquid concentration; diffusion
across the gas film is the rate-limiting process.  From these statements,
a modified Pick's Second Law expression can be written.

              dw/dt - Ak P.                              (2)
                        g A
     where    dw/dt » rate of desorption
                  A - area of gas-liquid interface
                 k  = diffusion coefficient
                  5
                 P. = equilibrium partial pressure of ammonia
The term, P., which defines the partial pressure of ammonia in equilibrium
with the liquid, can be expressed in  terms of the ammonia concentration
in the liquid and Henry's Law constant for ammonia.
                 PA
                       H
     where     C™  - ammonia  concentration  (mg/1)

                  H - Henry's  Law  constant

Only that portion of the  ammonia present  in  the non-ionized  (NH») form
is available for volatilization.   The  fraction of the  total  ammonia con-
centration in  the NH_ form is  a function  of  the pH and temperature.  As
shown  in Table 9 the fraction  F of total  ammonia concentration present
as volatile NH_ is sufficiently small  at  pH  values less  than seven to
preclude significant volatilization.   Values in Table  9  were calculated
from the following relationships :
                                        39

-------
            NH  + HO <± Nfit" + OH                      (4)
              J    Ł•      *T
                      = L»~4J  [OH ]

                          [NH3J





                  ' '  = [OH")                         (6)





     F =     l™^    =   [OH~]                       (7)







                                                      (8)
Table 9.  FRACTION OF TOTAL AMMONIA CONCENTRATION PRESENT AS NH3 AS A


          FUNCTION OF TEMPERATURE AND pH*


l<]

K]
[M3]
+ [NH3]
[OH"] =_
^
[OH'l
^ + fOH'l
K
w
PH
7
8
9
10
10
0.0018
0.018
0.22
0.65
Temperature ( C)
20
0.0040
0.038
0.30
0.80
30
0.0081
0.075
0.45
0.89
* Values  for K_ and K  taken  from Handbook of Chemistry and Physics
              D      W



A more useful expression  is obtained  by combining equations 2 and 3 while


substituting


            dCXTTT    -Ak  CV_T
             NH-      g   NH_
                3
             dt        H

Analytically, measurements of ammonia include both NH, and NH^.  The sum


will be  called  NH_  .
                                        40

-------
More usefully, equation 9 can be written
           <*  * - "*V   Cm*                      (12)
             HH3     „      NH3
Equation 12 is frequently simplified to
              *
          dC
            "3  -KC,,                              (13)
            dt       "3
               K = -Ak F                             (14)
                      e
                     H
In equations 14 and 15, K is a desorption rate constant.  When the natural
logarithm of the total ammonia concentration is plotted versus time, the
slope of the resulting line is equal  to minus K.

FROM LIQUID POULTRY MANURE

Ammonia desorption from liquid poultry manure was studied by Hashimoto and
Ludington   and the above analysis  used to  correlate their data.  Desorp-
tion tanks were formed by inverting 19  1  (5.0  gal.) plastic  carboys  from which
the bottoms had been  removed.  The  tanks were stirred and pH controlled.
This work   indicated the rate of desorption is highly dependent upon air
velocity over  the desorbing surface.  Values obtained for Ak /H from
equation 14 ranged from 0.05  to  0.09  per hour at  21   C and 0.037 to 0.061
per hour at  10° C.  Using these  data, ammonia escaping from  the surface
of their system at pH 8.0 and  20° C would  lower the nitrogen concentra-
tion by 3.3 percent per day.   At a  pH of 9.0 the  rate of decrease would
be 23  percent  per day.  Thus  pH  is  extremely important in estimating the
rate of ammonia desorption.

FROM CATTLE  FEEDLOTS

The escape of  ammonia from  cattle feedlot  surfaces  in northeastern  Colo-
rado was studied by Hutchinson and  Viets    by placing dilute acid
                                      41

-------
absorption traps at varying distances from cattle feedlots.  Their re-
sults, summarized in Table 10, show significantly higher rates of ammonia
absorption in the vicinity of feedlots as compared to samples gathered
in other rural areas.  The absorption of ammonia by the acidified absorbers
was twice that of distilled water.
Table 10.  MEAN AMMONIA NITROGEN ABSORPTION RATES BY DILUTE ACID TRAPS
           FROM 27 JULY 1968 THROUGH 27 FEBRUARY 1969 IN NORTHEASTERN
           COLORADO45
                                                  Mean weekly ammonia
                                              nitrogen absorption rate
  Site  description	kg/ha	
  No  feedlots within  3 km
  Small  feedlots  (200 head) at 0.8 km
  0.2 km east of  800  head feedlot
  2 km east of 90,000 head feedlot
  0.4 km east of  90,000 head feedlot
0.15
0.34
0.57
1.30
2.80
 FROM DAIRY PENS
 Additional work relative to the volatilization  of ammonia  from  livestock
                                                      46
 feeding areas was reported by Luebs, Laag,  and  Davis.    Using  dilute
 acid solutions in both  air sampling traps and surface traps,  they measured
 the concentration of ammonia plus  amine nitrogen in the  air near Chino,
 California.  It is in this area that approximately  400 dairies  serving
 the greater Los Angeles area are located.   In this  15,500  ha  (60-square-mile)
 area there are 123,000  dairy cows, 7,500 heifers and more  than  9,000
 calves.  Results of their  sampling (shown in Table  11) demonstrate  the
 increase of ammonia and amine nitrogen  concentration in  the dairy area
 compared to a nearby residential district.  In  Table 12  average weekly
 absorption of ammonia plus amine nitrogen by acid surface  traps is  com-
 pared for various areas near Chino,  California. Their data  indicated
 that distilled water had an absorption  rate equal to 58  percent of  that
 by acid surface traps,  thus one may conclude the area near the  Chino  air-
 port could be exposed to ammonia  at a  rate  up  to 220 kg/year/ha (200  lb/year/
 acre)  under the conditions measured.
                                       42

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Table 11.  ATMOSPHERIC CONCENTRATION OF DISTILLABLE NITROGEN (AMMONIA
           PLUS AMINE) NEAR CHINO, CALIFORNIA46


Location
Sampled
Brackett Field, 11.2 km
(7.0 miles) upwind of
dairy area
Chino airport in dairy
area, 0.8 km (0.5 miles)
from cows




Date
02-25-71
05-04-71
10-05-71
02-24-71
03-03-71
03-05-71
10-05-71
Distillable nitrogen
concentration
3
ug/m
1
2
3
39
37
46
69
Table 12.  AVERAGE WEEKLY ABSORPTION OF DISTILLABLE (AMMONIA PLUS AMINE)
           NITROGEN BY ACID SURFACE TRAPS NEAR CHINO, CALIFORNIA, JANUARY
                                   46
           11 TO FEBRUARY 15,  1972
Average weekly
Location kg/ha
Dairy area, 0.8 km (0.5 miles) from
cows
Urban area, 11.2 km (7.0 miles) NW
of dairy area
Poultry and citrus area, 34 km (21
miles) E of dairy area
Dryland agricultural area, 51 km
(32 miles) E of dairy area
National forest, 80 km (50 miles) SE
of dairy area
10.5

0.31

0.27

0.20

0.02

absorption rate
Ib/A
9.40

0.28

0.24

0.18

0.02

 Amine nitrogen  comprises  between five and 10  percent  of  the  total nitrogen
 absorbed by  acid  surface  traps  in the dairy area,  according  to  a limited
                                                 46
 number of analyses  done by Luebs, Laag and Davis.     Because the odor of
 amine compounds is  detectable at concentrations  less  than  one ppm in air,
 they concluded  amines  were undoubtedly important relative  to odors  from
 animal waste.

 A direct relationship  was found between the concentration  of ammonia plus
 amine nitrogen  and  the evaporation rate as measured  from their  sampling
                                       43

-------
traps filled with 0.01 normal sulfuric acid.  Thus, these data demonstrate
the greater volatilization of ammonia and other distillable nitrogen com-
pounds from dairy corral surfaces as evaporative potential increases.
This conclusion was also supported by the fact that the amount of nitro-
gen measured tended to be higher when air temperature was high and rela-
tive humidity was low. Secondly, ammonia concentrations were greater
during dry periods after the corrals had been wetted by rain.

FROM ANAEROBIC LAGOONS

An anaerobic lagoon receiving swine waste was analyzed for ammonia desorp-
                            47
tion by Koelliker and Miner.    This lagoon was operated as a flow-through
system with a theoretical detention time of about 60 days.  The lagoon had
a surface area of 2,700 square m (29,000 square ft).  A mass balance on the
lagoon had indicated that from November 1, 1969 to October 31, 1970,
5,600 kg (12,400 Ib) of nitrogen were introduced into the lagoon from the
swine waste.  During this same period, 2,100 kg (4,700 Ib) of nitrogen were
removed from the lagoon with wastewater for application to cropland.  Be-
cause the lagoon water level was lower in 1970 than in 1969, there was a
net decrease of 91 kg (200 Ib) in the accumulation within the system.
Thus, 3,600 kg (7,900 Ib) of nitrogen escaped from the system, apparently
because of ammonia desorption.  Their data for the rate of ammonia desorp-
tion were correlated as follows:
              d(NH3-N) =
              "It	       1  g
                                                         47
In this expression, K can be approximated by the formula:
                     K = 2.6 x loV'V1'4             (17)
where
         V = air velocity in ft/second
         T = temperature in degrees Kelvin
      P.P  = partial pressures of ammonia in the liquid and gas phases,
         °   respectively
         K, the overall rate transfer coefficient has units of
            pounds/day-square ft-atm
                                       44

-------
                                  SECTION VII

                      IDENTIFICATION OF ODOROUS COMPOUNDS

Considerable effort has been expended in identifying compounds evolved
by anaerobically decomposing manure.  This work has largely involved con-
centrating the specific chemical gases being evolved into some absorbing
solution or condensing trap followed by chromatographic analysis of the
accumulated material.

POULTRY MANURE

The odor of fresh and accumulated poultry manure was chromatographically
analyzed by Deibel.    He  found butyric acid,  ethanol and acetoin (3-hy-
droxy-2-butanone) to be the chief volatile  components of decomposing ma-
nure while fresh manure was found to be devoid of  these  compounds.

To identify the volatile compounds  of  odor  importance produced by chicken
               Oc
manure, Burnett   trapped  gases  in  a collection  column submerged in an
acetone dry ice bath.  A variety of column  packings  and  temperature con-
ditions were  used to effect  the  necessary separations.   When  0.5 micro-
liter  of prepared condensate  was injected directly into  the gas chromato-
graph, six peaks were  obtained which were identified as  acetic, propionic,
iso-butyric,  n-butyric,  iso-valeric and n-valeric  acids.   The butyric and
valeric acids have  very  disagreeable  odors.

                                     35
As  part of  the same project,  Burnett    also injected chloroform extracts
into a chromatograph fitted with an SE-30 column.   Indole  and skatole
were identified by  retention time comparisons with authentic  compounds.
 The detection of the nitrogen heterocyclic compounds, indole  and  skatole,
 is significant because of the strong,  harsh odors  of these compounds.
 Both indole and skatole are very tenacious  odorants which  tend to cling
 to clothing and other articles and to persist for long periods.  Burnett
 found approximately 18 times more skatole than indole and concluded that
 skatole was probably responsible, in part,  for the tenacious  character of
 poultry waste odor.
                                        45

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                                                  35
Using additional concentration techniques, Burnett   tentatively identi-
fied several additional compounds from poultry manure.   These were com-
pared with retention times of known compounds and evaluated by an odor
panel and postulated to be mercaptans and sulfides.  Thus, his conclusion,
which is compatible with those of other researchers in this area, indi-
cated that animal manure odors are a complex mixture of organic compounds
with characteristics mainly contributed by numerous chemical groups in-
cluding the organic acids as well as sulfur- and nitrogen-containing com-
pounds.

A direct relationship between odor level and the volatile fatty acid con-
                                                49
tent of liquid poultry manure was found by Bell.    Fatty acids were mea-
sured according to the procedure outlined in Standard Methods.    He sug-
gested an acceptable level based on odor control as being 0.1 percent or
less of fatty acids in liquid manure.

The microbiological-chemical changes occurring in poultry manure during
                                            27
storage were studied by Burnett and Dondero.    In their studies, dry
manure, 75 percent moisture, and wet manure, 85-90 percent moisture,
were stored for periods of up to 40 days.  They monitored the chemical
and biological changes taking place within the stored material as well
as the composition of gases produced.  They found the uric acid  content
of dry manure in storage dropped rapidly during the first seven  days.
The amine nitrogen content of the manure rose during the  first seven days
and remained at a value of roughly 0.5 mg/g dry weight of manure for the
next seven days.  Between day 14 and 22 the value dropped back to approxi-
mately the initial amine nitrogen concentration.  Ammonia evolution was
initially low but rose to a maximum value after about six days,  then fell
again.

A marked increase in odor intensity was noted in the liquid manure after
approximately 15 days.  The  uric acid  content fell  rapidly as was the
case with the dry manure.  The  ammonia content of  the liquid  rose rapidly
from approximately   100 mg/1 at the start of the experiment to a value
of approximately 1500 mg/1 after 10 days.  Beyond  this time the  ammonia

                                       46

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content remained essentially constant.  The concentration of soluble sul-
fides began to rise after approximately 17 days of liquid storage.   This
increase in soluble sulfides coincided with the dramatic increase in odor
concentration.  Although methane-producing bacteria were present from the
start, they did not begin to proliferate until after 28 days of storage.
Their earlier growth may have been inhibited because of the large,  volatile
organic acid concentration which developed during the early stages  of stor-
age.  Volatile organic acid concentrations increased to 1600 mg/1 by the
fourth day and remained at that level or higher for the next two weeks.   The
volatile organic acid concentration then decreased, allowing the methane
bacteria to grow.

A series of studies utilizing White Leghorn laying hen manure was conducted
by Ludington, Sobel, and Hashimoto    in which 75 g  of manure was put
into a five gal. carboy for study.  In one trial the manure was placed in
the carboy without additional water (25 percent solids) and in the second
trial the manure was diluted three to one with distilled water and the mix-
ture (6.0 percent solids) was placed  in the carboy.  Air at the rate of
28.3 1/hr (1.0 cu ft/hr) was passed through the carboys.  The exit air was
then analyzed for carbon dioxide, ammonia, and hydrogen sulfide.  In addi-
tion, odor panels made frequent observations on both systems to determine
the strength of the odor and the odor characteristics.  Both systems pro-
duced approximately six g of carbon dioxide daily.  The undiluted system
released 0.8 g of ammonia per day.  The production and release of hydrogen
sulfide was larger in the diluted than in the undiluted system.  Results
of  these studies are in Tables 13 and 14.

                                  52
A study was conducted by Hashimoto    in which a manure storage pit beneath
caged layers was aerated, using compressed air forced through plastic pipes.
Air was released to the liquid manure through 0.32 cm (1/8 in.) holes at 30.5 cm
(1.0 ft) spacing along the bottom of  the manure storage tank.  He recorded
the effects upon odor and also the changes of various water quality parameters.
With respect  to odor control, he found a strong correlation between the odor
offensiveness as rated by an odor panel and the ammonia concentration in the
room air.  In one series of trials in which the tank was initially seeded with
established oxidation ditch liquor containing large numbers of nitrifying
                                       47

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Table 13.  AMMONIA PRODUCTION BY WHITE LEGHORN LAYER MANURE ADDED DAILY TO
           A  NINETEEN LITER (FIVE GALLON)  CARBOY51
                                                       System
                                              Diluted         Undiluted
Manure feed rate (g/day)
Water feed rate (g/day)
Solids content in feed (percent)
Duration of trial (days)
Air flow rate (1/hr)
Ammonia added in manure (g/day)
Ammonia added during run (g)
Ammonia in carboy after trial (g)
Ammonia released to air (g)
Ammonia content of exit air
maximum (micrograms/1)
Odor:
Vapor dilution to threshold
Quality
75
225
25
50
28
0.37
18.5
48
3
i?n


1000-2500
o f f ens ive , s our
75
0
6
50
28
0.4
20
25
15



1000-2500
ammonia-like
Table 14.  HYDROGEN SULFIDE PRODUCTION BY WHITE LEGHORN LAYER MANURE ADDED
           DAILY TO A NINETEEN LITER (FIVE GALLON)  CARBOY51
System
Diluted Undiluted
Manure feed rate (g/day)
Water feed rate (g/day)
Solids content of feed (percent)
Air flow rate (1/hr)
Sulfide added in manure (mg/day)
Sulfide added during trial (g)
Sulfide in carboy after trial (g)
H-S concentration in air,
maximum (micrograms/1)
Final pH in carboy
Percent sulfide present as H«S at
this pH
Comparative level of offensiveness
75
225
25
28
21.2
1.06
53.5

0.011
7.5

20
high
75
0
6
28
21.2
1.06
5.65

0.005
9.0

0.85
low
organisms, the ammonia content of the room air was held to less than 2 ppm
during the first  100 days of the trial.  During this same period the odor
level within the  room was  judged to be very faint.  In another trial in
which the tank was not seeded, the ammonia concentration of the air averaged
eight  to 10 ppm  during the first 60 days and the odor was judged definite
to strong throughout this period.  Thus he concluded that nitrification
was helpful in odor control and that seeding the manure slurry was benefi-
cial in establishing nitrification during the early stages of the storage.
                                       48

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CATTLE FEEDLOTS

                                                        53
Various attempts were described by Fosnaugh and Stephens   to measure odor-
ous compounds in the vicinity of cattle feedlots.  Although none of the
techniques proved entirely satisfactory, they tentatively concluded that
trimethylamine, propylamine, butylamine, and ethyl- or methyl-amine were
present in the odorous air near feedlots in concentrations above their
odor thresholds.  The more promising techniques they described are sum-
marized in Table 15.

                                       54
Work was reported by Bethea and Narayan   concerning the identification of
odorous compounds evolved from beef cattle manure.  In their initial ex-
ploratory work, a small volume of fresh manure was diluted with water and
placed in a flask and maintained under aerobic conditions.  The gas re-
leased from this flask was then passed through a series of selective ab-
sorption flasks containing dilute hydrochloric acid, ether, sodium bicar-
bonate, sodium hydroxide or sulfuric acid.  The material from the various
absorption flasks was then subjected to chromatographic analysis and the
following four classes of compounds were found:  alcohols, amines, alde-
hydes, and esters.  The fact that mercaptans and other organic sulfides
were not detected may be attributed to the aeration of the manure during
the absorption test.  Following this work, gas samples were collected from
confinement chambers in which a steer was fed 10 kg  (22 Ib) of a standard
roughage concentrate ration daily.  The three manure management schemes
used were:  (a)  chamber thoroughly cleaned and washed every day; (b) ma-
nure shovelled out  daily and no washing; and (c) no cleaning.  Air from
the chambers was bubbled through four selective absorption traps and these
traps analyzed for  odorous compounds extracted from the air.  The data in
Table 16 summarize  the results of these experiments.  In addition to the
compounds listed in Table 16, carbon dioxide, carbon monoxide, ammonia
and hydrogen sulfide were reported as present under all three manure manage-
ment schemes.

In work to analyze  amines in the air over a dairy manure sample, White
      37
et al.   first conducted a selective absorption of the amine compounds in

                                       49

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       Table 15.  ODOROUS GAS DETECTION AND IDENTIFICATION SCHEMES EVALUATED BY FOSNAUGH AND STEPHENS
                                                                                                     53
        Scheme
                          Concentration
                            technique
                Known compounds
                    tested
              Comments
        Paper chromatography
                            1.2 N HC1
                 amines
Possibly detected trimethylamine
  near feedlot
Ul
o
Ammonia-amine absorp-
  tion on silica gel
  treated with ninhydrin
none
                 none
Ammonia and amines suggested at
  concentration less than 1 ppm
        Gas chromatography
          electron capture
          detector
                            0.1 N HC1
                 none
No results
        Gas chromatography
          flame ionization
          detector
                            1.2 N HC1
                 methylamine
                 t rimethylamine
                 ethylamine
                 n-propylamine
                 n-butylamine
Presence of amines indicated

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Table 16.  ODOROUS COMPOUNDS IDENTIFIED FROM THE ATMOSPHERE IN A BEEF
           CATTLE CONFINEMENT CHAMBER UNDER THREE MANURE HANDLING PRO-
                54
           GRAMS
  Clean, and wash daily    Shovel out daily
                      No cleaning
  Methanol
  Acetaldehyde
  Ethanol
  iso-Butyraldehyde
  Ethyl formate
Methanol
Acetaldehyde
Ethanol
2-Propanol
Skatole
Indole
Ethyl formate
iso-Butyl acetate
Methanol
Acetaldehyde
Ethanol
2-Propanol
Skatole
Indole
Ethyl formate
Propion aldehyde
Methyl acetate
iso-Propyl acetate
iso-Propyl propionate
iso-Butyl acetate
1.2 N HC1.  After selective absorption, the solution was neutralized with
sodium hydroxide and heated to drive the amine compounds into a super-cooled
injection needle.  The collected amines were analyzed with chromatographic
equipment.  The column used was a 3.05 m (10 ft) stainless steel column
packed with five percent  (by weight) tetrahydroxyethylethylenediamine (THEED)
and 15 percent (by weight) tetraethylenepentamine (TEP) on Chromosorb W.
A column temperature of 47  C was maintained for these tests.  With this
approach, they were able  to identify trimethylamine and ethylamine in the
headspace over both anaerobic and aerated dairy waste.

SWINE MANURE

In early work to identify gases involved in the odor associated with con-
finement swine buildings, Day, Hansen and Anderson   used a U tube submerged
in a dry ice-acetone mixture to condense the compounds of interest.  The
condensate was subjected  to spectral analysis.  Other qualitative techniques
were used to detect hydrogen sulfide and ammonia.  They noted that the
                                      51

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 filter paper preceeding the cold trap was accumulating not  only dust but
 also  a strong,  objectionable odor characteristic of the swine  unit.
 From these efforts, they identified hydrogen sulfide,  methane, carbon
 dioxide,  and ammonia as being present in the buildings.

 Work reported by Merkel et al.   utilized a variety of selective absorp-
 tion techniques followed by chromatographic analyses to identify specific
 compounds present in the atmosphere of a swine confinement  building.  Di-
 lute hydrochloric acid was used to absorb ammonia and amines.  A mercuric
 chloride-mercuric cyanide solution was used to absorb sulfur containing
 compounds.  Propylene glycol, which has a high absorption for  organic
 alcohols, was used to isolate those compounds.  Carbonyls were collected
 by  using  an absorption solution of dichloro methane.  Using this procedure
 they  were able  to conclude that amines, amides, alcohols, sulfides, di-sul-
 fides, carbonyls and mercaptans were contained in the atmosphere of the
 swine confinement building in addition to the fixed gases:   carbon dioxide,
 methane,  ammonia and hydrogen sulfide.  The alcohols specifically identi-
 fied  were methanol, ethanol, N-propanol, iso-propanol, n-butanol, iso-bu-
 tanol and iso-pentanol.   Among the carbonyls identified were formaldehyde,
 acetaldehyde, propionaldehyde, iso-butyraldehyde, heptaldehyde, valeralde-
 hyde, octaldehyde and decaldehyde.  Based upon physiological investigation
 they  concluded  that the major constituents of the odor were the amine and
 sulfide groups.

 To  check  for the presence of carbonyl compounds in a swine building,
 Hartung et al.    used an absorption column consisting of glass beads, coated
with  a layer of  2,4 dinitrophenylhydrazone.  In making the absorption col-
 umn,  two  grams of silica gell were stirred with two ml of the  DNPH.
The powder was then slurried in carbonyl-free hexane and transferred to  the
 column.   Carbonyl-free air was used to evaporate the hexane from  the column
and then  the column was transferred to the swine atmosphere of interest.
The air sample was  pulled through the column by the use of a vacuum pump
and then  the column was  transferred to the laboratory for carbonyl recovery.
Carbonyl-free hexane was used to elute the DNPH derivitive of  interest
                                        52

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the column.  The eluted material was evaporated to a small volume then
placed on thin-layer chromatography plates.  Using this technique,  the
presence of the following carbonyl compounds was shown:  ethanal, pro-
panal, butanal, hexanal, acetone, 2-butanone and 3-pentanone.   They con-
cluded that propanol, acetone, and 2-butanone probably contributed to the
overall odor through additive effects even though only ethanal was mea-
sured in concentrations exceeding its threshold odor concentration.

To detect the presence of amines in a swine building atmosphere, Miner
and Hazen  pumped the air through a solution of five percent acetic acid
in water.  The ammonia and amines were selectively absorbed from the air
while the acetic acid was stripped from the liquid.  After a period of
aerations, the liquid was subjected to chromatographic analysis.  Analy-
ses were conducted using a 4.6 m (15 ft), 0.32 cm (1/8-in.) diameter stain-
less steel column packed with Porapak Q.  This work indicated the presence
of methylamine, ethylamine and triethylamine in the air inside a swine
building in which manure was being stored beneath partially slotted floor-
ing.  Since all three of these compounds have low threshold odor levels,
they were judged to be contributing to the odor.
The concentration of various gases in the atmosphere of an enclosed swine
building was determined by Lebeda and Day.    Air was analyzed under two
conditions:  (a)  when the unit was ventilated at a rate of 1.0 cu m per
minute (35 cu ft per minute) per animal and (b) when the forced ventilation
had been turned off for six hours.  Results of these analyses are given in
Table 17.  None of the gas concentrations measured reached levels considered
harmful to humans.

Table 17.  GAS CONCENTRATIONS MEASURED IN AN ENCLOSED SWINE UNIT WHEN VENTI-
           LATED AND WHEN VENTILATION HAD BEEN INTERRUPTED FOR SIX HOURS57
                                           Concentration, ppm
                                                      Nonventilation for
  Constituent	Ventilated	six hours	
  Ammonia                              7.4                   18.8
  Carbon dioxide                     656.0                4,286.0
  Hydrogen sulfide                     0.09                   0.28
  Sulfur dioxide                       0.026

                                      53

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MISCELLANEOUS MEASUREMENTS

The soil atmosphere beneath a cattle feedlot was compared to the atmosphere
beneath a cropped field by McCalla and Elliott?8 They used gas diffusion
bottles and  then returned the collected samples to the laboratory for a
chromatographic analysis.  A more reducing  atmosphere was present beneath
the cattle feedlot as  indicated by higher carbon dioxide and methane con-
centrations  as well  as lowered  oxygen and nitrogen content.

A Burrell  gas analyzer with absorption  pipettes and  oxidation heaters was
used  by White and Taiganides    to measure carbon  dioxide, carbon monoxide,
oxygen and illuminants.   A copper oxide heater was used to measure hydro-
gen and a  catalytic  heater was  used for the paraffin hydrocarbons.  An
Orsat gas  analyzer was used  to  measure  carbon dioxide,  carbon monoxide,
and oxygen.   These analyses were conducted  on gas produced  during the py-
rolysis  of animal manures.

A modification of  the chemical  oxygen demand analysis as  used  in waste-
                                          59
water studies was  employed by Frus  et^ a^.    to measure organic gases in
a swine  building  atmosphere.   The technique was sensitive to significant
changes  in odor level and to rates  of ventilation within the building.
Difficulties with the procedure were associated with reproducibility and
variable sensitivity to gases depending upon their solubilities and ease
of  oxidation.
 SUMMARY

 The identification of specific gases responsible for livestock and poultry
manure odors has proven a difficult and tedious task.  Identification of
the common and most abundant gases has not satisfactorily explained the
observed odors.  The research findings indicate that the odorous gases are
primarily the end and intermediate products of anaerobic decomposition
which  have sufficient volatility to escape from the liquid phase.

The primary tool for odorant identification has been gas liquid chrom-
atography.   Thin layer chromatography and mass spectrescopy have received
                                        54

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limited use.  The major limitation in specific compound identification
has been the low concentrations at which the odorants are present.   Many
of the compounds have perceptible odors at concentrations of less than
one part per million and less than the minimum detectable concentration
of the most sensitive detectors available on gas chromatographs.   When
highly sensitive detectors have been employed, frequently it has  been
found that other compounds, present in many times greater concentrations
but of less odor significance, tend to interfere with the analyses.

To overcome the problems of detecting these low concentrations, various
selective enrichment schemes have been utilized.  The use of cold traps
in which the odorous gases were passed through a U-tube submerged in a
cold liquid, dry ice-acetone or liquid nitrogen has been helpful but
suffers from a lack of selectivity.  Solid media covered with selective
absorbents have been successfully used as have general absorbents which
are brought into equilibrium with the odorous gas.  Selective liquid ab-
sorbents, dilute acid  for  ammonia and amines, mercuric salt solutions for
sulfur-containing  compounds, propylene glycol for alcohols and dichloro-
methane for carbonyls  have been most commonly used and with general success,

An examination of  the  lists of compounds  isolated from the air in  contact
with anaerobically decomposing manure  (Table  18) documents the existence
of a large number  of compounds of potential importance in odorous  air.
This large  list  also exemplifies  the complexity of odor analysis.  This
list further  explains  the  variability in  characteristics commonly  attri-
buted  to  animal  waste  odors.   Changes in  feed rations, animal physiology
or manure handling may be  expected  to alter the quantitative make-up of
the volatile  by-products of manure  decomposition, thus, the exact  nature
of the odor produced by a  livestock operation.
                                        55

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Table  18,   COMPOUNDS  IDENTIFIED IN THE AIR FROM THE ANAEROBIC DECOMPOSI-

            TION OF LIVESTOCK AND POULTRY MANURE
  Alcohols  (1.8)

   Methanol (1,8)
   Ethanol  (1,8)
   2-Propanol (1,8)
   n-Propanol (8)
   n-Butanol (8)
   iso-Butanol (8)
   iso-Pentanol (8)
  Acids  (6)

   Butyric  (7,6)
   Acetic  (6)
   Propionic (6)
   iso<-Butyric (6)
   iso'-Valeric

  Amines  (1.2.4.5)

   Methylamine (4)
   Ethylamine  (2,4)
   Trimethylamine  (2)
   Triethylamine (4)
                       Carbonyls (1,3.8)

                        Acetaldehyde (1,3,8)
                        Propionaldehyde (1,3,8)
                        iso-Butyraldehyde (8)
                        Hexanal (3)
                        Acetone (3)
                        3-Pentanone (3)
                        Formaldehyde (8)
                        Heptaldehyde (8)
                        Valeraldehyde (8)
                        Octaldehyde (8)
                        Decaldehyde (8)

                       Sulfides (2.6)

                        Dimethyl sulfide (2)
                        Diethyl sulfide (2)

                       Nitrogen heterocycles (6)
                        Indole (6,1)
                        Skatole (6,1)
                                                    Esters  (1.2)

                                                     Ethyl  formate (1)
                                                     Methyl acetate (1)
                                                     iso-Propyl ace-
                                                       tate (1)
                                                     iso-Butyl ace-
                                                       tate (1)
                                                     iso-Propyl pro-
                                                       pionate (1)
                                                     Propyl acetate (2)
                                                     n-Butyl acetate (2)

                                                    Fixed gases

                                                     Carbon dioxide
                                                     Methane
                                                     Ammonia
                                                     Hydrogen sulfide

                                                    Mercaptans (2,6)

                                                     Methylmercaptan (2)
                                                    Disulfides (6)
Note:  Numbers in parentheses refer to the references below in which iden-
       tification was  reported.
  1.  R. M. Bethea and R.  S.  Narayan 1973. 54
6.

7.

8.
                                 37

                                 56
2.  R. K. White, eŁ al.   1971.

3.  L. D. Hartung eŁ  al.   1971

4.  J. R. Miner and T. E.  Hazen 1969. 6

5.  J. Fosnaugh and E. R.  Stephens 1969.

                       35
                                           53
      W. E. Burnett  1969.

                         48
    R. H. Deibel 1967.

    J. A. Merkel 1969.
                         36
                                      56

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                                  SECTION VIII

               MEASUREMENT OF SPECIFIC ODOROUS GAS CONCENTRATIONS

Although a large number of gases have been identified as being released
from animal manure during transport, storage, treatment and disposal,
only a limited number of these have been routinely measured as parameters
of odor intensity.  It is the purpose of this section to summarize those
procedures in current use so they might be readily available to people
working in the area and to aid people utilizing air analyses to more
intelligently interpret the data.

AMMONIA

The most widely  used method of analysis  giving satisfactory results in-
volves selective ammonia  absorption followed by color  formation using
Nessler's  reagent.  Recommended  absorbing solutions include two percent
boric acid in  ammonia-free water   and a diluted  sulfuric  acid solution
                                                                  60
made  by  adding one ml  concentrated sulfuric  acid  to  10  1 of water.
A measured quantity of absorbing solution is placed  in an  absorption
 flask or impinger and contacted with a measured  air  volume.   Using  fresh
 absorbing solution as  a blank,  the absorbed  ammonia  is measured by  add-
 ing Nessler's  reagent.  Color intensity is best  measured at 425 my.
 Directions for the preparation of Nessler's  reagent  are found in  Stan-
 dard Methods50 or it can be purchased commercially already prepared.
 Results are most appropriately expressed as  parts per million by  volume
 or micro grams per liter.  This method was used by Burnett and Dondero
                        6
 and by Miner and Hazen.

 Another technique for estimating ammonia concentrations in air is based
 on the equilibrium distribution of ammonia in water and in the surround-
 ing atmosphere.  At equilibrium, the partial pressure of ammonia in water
 is equal  to its partial pressure in the surrounding atmosphere.   The
 ammonia content of a  distilled water  containing ammonia can be estimated
 from a pH measurement, knowing  the  temperature of the solution and the

                                         57

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 appropriate dissociation constants.  Kowalki  et_ &L.    developed a rela-
 tionship between ammonia content  in water and its  partial pressure.  Thus,
 by bringing a distilled water into equilibrium with  an air sample contain-
 ing ammonia, it is possible to estimate the ammonia  concentration of the
 air based upon the ammonia content of  the water.   The pH of  the water can
 be used as a measure of the equilibrium ammonia content.  This general
                                            47
 approach was utilized by Koelliker and Miner    in  estimating the ammonia
 loss from an anaerobic lagoon. Table  19 represents  the calculated pH val-
 ues of water in equilibrium with  various concentrations of ammonia in air.

 Table 19.  CALCULATED pH VALUES OF DISTILLED  WATER IN EQUILIBRIUM WITH
            VARIOUS AMMONIA CONCENTRATIONS IN  AIR AT  20° C
ppm vol.

1
5
10
50
100
500
P
g

1 x
5 x

5 x
5 x
= PL
-6
10 °
10
10 S
10 .
10,
io-4
pH of
water

9.5
9.9
10.0
10.4
10.5
10.9
                                                                 6?
This general  technique was  utilized  by Mourn,  Seltzer and Goldhaft   in
devising a quick method  for estimating the ammonia content  of air.  In
their procedure, pH test paper  is moistened with distilled  water and con-
tacted with the air for  15  seconds.  At that  time, the pH is recorded and,
using the data from Table 20, the ammonia content is estimated.  Special
packets for this purpose, consisting of pH paper, a calibration color card
which interprets color directly as ammonia content, and a bottle for carry-
ing distilled water, all in a single case, are marketed by  Vineland Lab-
oratories, Vineland, New Jersey.

Table 20.  AMMONIA CONCENTRATION (ppm)  IN AIR BASED ON THE  pH OF A TEST
           PAPER AFTER 15 SECONDS OF CONTACT62
pH
6
7
8
9
10
11
NH« concentration
0
5
10
20
50
100+
                                       58

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HYDROGEN SULFIDE
Modifications of the method for analyzing hydrogen sulfide concentra-
tions in wastewater as prescribed in Standard Methods   have been widely
adopted for gas analysis.  In essence, a measured volume of gas"is passed
through two absorption flasks in series, each containing 100 ml of 0.1 N
zinc acetate solution.  Similarly, a cadmium hydroxide suspension can be
                        63
used for the absorption.    The hydrogen sulfide reacts to form a zinc
or cadmium sulfide suspension.  The sulfide content of the suspension may
be measured by a titration or a colorimetric procedure.
In the titration procedure, excess 0.025 N iodine solution is added to
each of the absorption  flasks  along with 2.5 ml of concentrated hydro-
chloric acid.  The  contents of the flasks are then combined and the ex-
cess iodine titrated with  0.025 N sodium thiosulfate.  The quantity of
iodine utilized in  oxidizing the sulfide ion is a measure of the sulfide
content of the air.

In the colorimetric procedure, a solution of acidified N, N-dimethyl-p-
phenylenediamine oxalate and one of ferric chloride  are added to the zinc
sulfide suspension.  Methylene blue will be formed in proportion to the
amount of sulfide present.  The intensity of methylene blue color can be
estimated or measured using a  spectrophotometer at 600 my.    This proce-
dure is described for use  in air pollution studies by Jacobs.    Reagents
for  this procedure  are  marketed by Hach Chemical Company of Ames, Iowa.

MERCAPTANS

The  mercaptans or organic  thiols have  been identified as a group as being
important in animal waste  odors.  Thus far, they have not been routinely
measured by  researchers dealing with  livestock waste odors but have been
detected as being present  in the odor  given off from cattle feedlots
                                      cc.                   "\~]
and  listed by Merkel, Hazen and Miner   and by White et^ aiU   as being
present in the odors  from  anaerobic decomposing swine and dairy cattle
manures.  A method  for  the quantitative measurement  of  the mercaptans has

                                       59

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                                                          /• o
been  published by  the American Public  Health Association.    In principle,
 the technique is  to absorb  the mercaptans by passing  a known volume of air
 through an aqueous solution of mercuric  acetate-acetic acid.  The collect-
 ed mercaptans are  subsequently determined by a spectrophotometric measure-
 ment  of the red  complex produced by the  reaction between  mercaptans and a
 strongly acid solution  of N,N,-dimethy1-p-phenylenediamine  ferric chloride.
 The method determines total mercaptans and  does not differentiate among in-
 dividual mercaptans although it is  reportedly  more sensitive for the lower
 molecular weight  alkane thiols.

 The technique is  designed to provide a measurement of mercaptans in the
                     3
 range below 200  yg/1  (102  parts/billion).   For concentrations above
 100 parts/billion, the  sampling period can  be  reduced or  the liquid vol-
 ume increased either before or after aspirating.  The minimum detectable
 amount of ethyl me reap tan is 0.04 jag/ml  in  a final liquid volume of 25 ml.
 When  sampling air  at the maximum recommended rate of  one  1/min for two
 hours,  the minimum det<
 ppb methyl mercaptan).
                                                                 3
hours, the minimum detectable mercaptan concentration is 3.9 ug/m  (2.0
The N,N-dimethyl-p-phenylenediamine reaction is also suitable for the de-
termination  of other  sulfur-containing compounds including hydrogen
sulfide  and  dimethyl  disulfide.   The potential for interference  from these
latter compounds  is especially  important  since all these compounds com-
monly coexist in  odorous  air.   By appropriate selection of the color for-
mation conditions, the  interference from  hydrogen sulfide and dimethyl
disulfide  can be  minimized.

The procedure involves  collection of the  sample by passing air through
15 ml of an  absorbing solution  of 50 g of mercuric acetate and 25 ml of
an absorbing solution of  50  g of  mercuric acetate and 25 ml  of glacial
acetic acid  diluted to  one 1.   The sample,  after exposure to a known
volume of  air, is removed from  the aspirator,  diluted to 25  ml and the
color-forming agent added.   The color-forming reagent is a mixture of a
solution of N,N,-dimethyl-p-phenylenediamine hydrochloride and a solution
of ferric  chloride hexahydrate.   Directions for the mixing and formulation
of this color-forming reagent are contained in the reference.    A standard
                                        60

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mercaptan solution can be made by weighing out an appropriate quantity
of lead mercaptide and diluting to an appropriate concentration.

VOLATILE ORGANIC ACIDS

Volatile organic acids are produced as an intermediate breakdown product
of carbohydrates.  In a well-operating anaerobic digestion system, the
volatile organic acids are decomposed as produced and, ideally, never
reach such a high  concentration  as to reduce  the overall pH of  the solu-
tion.  Traditionally, when anaerobic digestion systems have failed,
an excess of volatile acids  has  been noted  to accunulate, thus  monitor-
ing  of the organic acid  content  has been one  method  for controlling
anaerobic digestion.  Associated with the accumulation of organic acids
has  been a sharp change  in the odor characteristics  of digesting materials.
For  this reason, it  is not surprising that  volatile  acids are produced
during the anaerobic decomposition of animal  manures and that they are
related to the observed  odor characteristics.

There are  two  methods for the analysis  of  organic volatile  acids:
 (a)  the distillation technique,  and  (b)  the chromatographic technique.
The  basic  philosophy in  the  distillation technique was  summarized by
Sawyer.6^   In this procedure, a liquid  sample is acidified  with sulfuric
 acid to  adjust pH to less than 1.0.   At this  pH, the volatile acids  are
 in the nonionized form and exert their  maximum vapor pressure.   They may
be distilled from the solution by either direct heating or  by steam  in-
 jection.   The direct heating is more rapid but more  subject to  error than
 steam injection distillation.  The technique involves distillation of the
 volatile acids and their collection followed by titration with  a dilute
 standard base.  Recovery of volatile acid is consistently  less  than
 100 percent using either of these procedures.  Thus, it is  necessary to
 determine the efficiency of the particular apparatus being used and  to
 include this efficiency in calculating the final results.

 In  the partition  chromatography technique, a solid  absorbant - in this case
 silicic acid- is  placed in a  column and a sample of the liquid containing

                                        61

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the volatile acids is placed on top of the column.    Once the acidified
sample is placed on the silicic acid, a mobile phase is passed through
the column.  The mobile phase  is a mixture of chloroform and butanol.
This mixture selectively carries with it  the nonionized volatile acids
which are more soluble in this mixture than in the stationary water phase.
The sulfuric acid and other ionized salts, however, are more soluble in
the water and so are left behind.  The extracted volatile acids are then
measured by titration with sodium hydroxide to the phenolphthaline end-
point as is done in the distillation procedure.

Both of the above techniques can be modified for the measurement of vola-
tile acids in air.  The usual method is to collect a sample by bubbling
a measured volume of air through a dilute alkaline solution for the absorp-
tion of volatile acids.  Once  the organic acids from a measured volume of
air have been extracted, the absorbing solution is acidified with sulfuric
acid and the volatile acid concentration  determined by either distillation
or by partition chromatography.
                                      62

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                                  SECTION IX

                       QUANTITATIVE MEASUREMENT OF ODORS

The technological difficulties of quantitative odor measurement are for-
midable.  As explored earlier, odor is essentially a subjective response
to the mixture of chemical compounds present in the air.  This response
is a function not only of the chemical make-up of the air but also is
dependent upon the psychological disposition of the observer as well.
Evaluation of an odor is thus a complex physiological and psychological
process and it is little wonder that techniques for quantitative measure-
ment of odors have been fraught with difficulty.  Two separate aspects
of odor can be identified:  strength or intensity and quality.

ODOR STRENGTH

Odor strength or intensity is the more direct and easily measured of the
two aspects.  The current concept is that each odor source may be diluted
sufficiently with odor-free air to be indistinguishable from odor-free
air by the human nose.  That concentration which is barely distinguishable
from odor-free air is termed the threshold odor.  The strength of an
actual odor can be defined in terms of the number of dilutions with odor-
free air  required to reduce the odor to the  threshold concentration,

Similar to the air dilution technique, a liquid dilution technique can be
used.  A  liquid which has an odor can be diluted with odor-free water un-
til the liquid odor  is no longer distinguishable from that of odor-free
water.50  Both the air dilution and  liquid dilution techniques have been
used in evaluating animal waste odors,

In the  liquid dilution technique, a  sample of the odorous material is mix-
ed with odor-free water.  Generally, the diluted sample along with some
odor-free samples are then offered to a panel of observers.  General  tech-
nique is  to make up  a series of five bottles to offer to the panel,  two
containing a dilution of the odorous material and the other three

                                      63

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containing odor-free water.  Panel members are asked to mark on their
score sheet  those bottles which contain the odorous material.  By making
a series  of  dilutions  and offering them to the odor panel for evaluation,
minimum detectable  concentration of the material can be determined.   By
making  the liquid dilutions  successively greater by a factor of two,  those
data can  be  used to determine  an odor intensity index (Oil).  In other
words,  if the threshold odor was determined to be at a dilution of 15 parts
odor-free water to  one part  of odorous solution, the odor intensity  index
would be  four.   The other means of expressing this information would be as
the threshold odor  number  (TON).  Threshold odor number is equal to  two
                                                               28
raised  to the odor  intensity power.  Using this approach, Sobel   measured
the odor  intensity  index and threshold odor number of a series of diluted
chicken manure samples stored  over a period of six weeks.  The odor  inten-
sity of undiluted manure remained essentially constant at nine or a  threshold
odor number  of 512.  For manure diluted three to one, he found the initial
odor intensity  index to be equal to nine but after the first week the odor
of  this material increased so  that at the end of three weeks he measured
an  odor intensity index of 15  or a threshold odor number of 32,768.

The vapor dilution  technique involves actual dilution of odorous air with
                                           28
odor-free air.   Using  this technique, Sobel   measured the dilution which
is  the  ratio of the volume of  odorous air divided by the volume of odor-
free dilution air which is offered to the observer.  The dilution as used
in  this technique is essentially equivalent to the threshold odor number
of  liquid measurements.  Using this approach, he again demonstrated that
the odor  of  diluted manure was considerably more intense than the odor
of  undiluted manure.   He also  concluded that the quality of  the odor from
the diluted  manure was considerably more offensive to the panel than the
ammonia-like odor from undiluted manure.

The  odor  of  stored dairy cow manure was studied by Earth, Hill and Polkowski.
By using  various aeration rates, they were able to produce a variety of odor
intensity indexes as well as variable concentrations of volatile acids,
ammonia,  and hydrogen  sulfide.  Their results are summarized in Table  21.
From these studies correlations were developed relating the  concentrations

                                       64

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of the three odorants in the liquid manure to the observed odor inten-
sity index.  Those relationships are as follows:

   Oil = 3.04 C°'2°                      R = 0.92           (18)
   Oil = 0.64 C^ °*46                      R = 0.71           (19)
   Oil = 11.5 0. c°*°9                      R = 0.80           (20)
              -H2S
   Oil = 2.70 (CVOA°'21 CR s~°'01)          R = 0.72           (21)
   Oil = 10,88 (CVOA°-28 Cm -°'°4)         R = 0.94           (22)
   011 - 10'2 
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 of people to accurately describe odors.  One device on the market for the
 estimation of odor intensity is the scentometer.    The scentometer is
 essentially a rectangular, plastic box containing two air inlets (one for
 each activated charcoal bed) and four odorous air inlets; 0.159, 0.318,
 0.635 and 1.27 cm (1/16, 1/8, 1/4 and 1/2 in.) in diameter.67  The odorous
 inlets are directly connected with a mixing chamber and the nasal outlets.
 See Figure 6.

 Table 21.  ODOR INTENSITY INDEX AND ODOROUS COMPONENTS IN THE SUPERNATANT
            OF LIQUID DAIRY MANURE RECEIVING VARIOUS RATES OF AERATION66

Aeration Aeration
Rate, Depth
Unit cc/min cm Week
2 400 36 1
2
3
4
5
3 300 43 1
2
3
4
5
60 01
2
3
4
5
7 300 20 1
2
3
4
5
Odor
Inten-
sity
Index
10.0
8.5
11.0
12.0
13.0
9.0
8.0
10.0
11.5
12.0
14.5
16.5
15.5
14.0
16.0
8.5
9.8
10.0
11.0
12.0
Odorous

V.O.A. ,
mg/1
309
512
481
724
1182
275
565
588
678
900
1566
3290
3950
4940
6900
238
634
733
988
3740
components in liquid

NH3-N
mg/1
340
448
473
632
785
341
484
547
512
840
510
660
843
1007
1444
396
476
570
735
1108

H2S-S* PH
mg/1
.30 8.21
a .51
a 8.63
.20 8.56
b 8.57
.20 8.22
a 8.61
a 8.65
.10 8.63
b 8.55
6.6 7.24
13.8 7.15
11.7 7.14
23.5 7.08
b 6.69
.30 8.33
.30 8.47
1.50 8.50
.90 8.47
b 8.24
*Definition of symbols:   a.   Insufficient  component  present to give positive
                              result.
                          b.   No  determination made.
In field operations, the observer takes  the scentometer where the odor
intensity is to be measured.  He places  the device to his nostrils, cover-
ing the odorous air inlet ports with his fingertips and breathes through
the instrument to adjust his sense of smell to odor-free air.  The concept
                                       66

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            FIG. 6    SCENTOMETER
67
ODOROUS AIR
INLET PORTS
                                                            SNIFFING
                                                             PORTS
      SCREEN ON BOTH
       SIDE OF CHARCOAL
       FILTER

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 is that any air entering his nostrils under these conditions will have
 passed through the activated charcoal beds and be odor free.  Once his
 sense of smell has become acclimated to odor-free air and his sense of
 smell rested to the point of maximum sensitivity, the ports are opened in
 successively larger diameters beginning with the smallest port.  He con-
 tinues in this manner until an odor is first detected coming through the
 device.  The design is such that odorous air is mixed with the filtered
 air in definite proportions so that recording the port or ports that
 were opened at the time he first detected an odor provides a measure of
 the dilutions required to reach the odor threshold.  Table 22 provides
 a correlation between the ports which are open and the calculated dilu-
 tion which is entering the nostrils of the observer. By having a combina-
 tion of ports open, it is possible to estimate odor dilutions through
 thresholds ranging from 1.47 to 170.  Measurements made with more than  one
 port open, however, are subject to question because of the frequent
 Table 22.   DILUTION TO THRESHOLD VALUES WITH VARIOUS PORTS OPEN ON A
            SCENTOMETER WHEN AN ODOR IS BARELY DETECTABLE
*
Odorous Air Inlets
Dilutions
to Threshold
1.47
1.49
1.55
1.88
2.00
5.55
5.75
6.75
7.00
27.00
31.00
170.00
1.27 cm
(1/2 in.)
0
0
0
X
0
X
X
0
X
X
X
X
0.635 cm
(1/4 in.)
0
0
0
0
X
0
0
X
0
X
X
X
0.318 cm
(1/8 in.)
0
0
X
X
X
0
0
0
X
0
0
X
0.159 cm
(1/16 in.)
0
X
X
0
X
0
X
X
X
0
X
0
*Definition of symbols:  x indicates port  is  covered
                         0 indicates port  is  open
                                       68

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inability of the observer to detect small differences in odor inten-
sity.
                                          Ł O
In discussing the scentometer, Huey &t_ a^.   stated that their experience
had shown that odors above seven dilutions to threshold would probably
cause complaints while those measuring 31 dilutions to threshold could
be described as a serious nuisance if they persist for a considerable
                                                                 69
length of time.  The scentometer was described in a paper by Rowe   in
which he indicated that it required about ten times the perceptible odor
threshold to give a definite sensation of odor and another tenfold in-
crease of odor to be considered a strong odor.

The scentometer has received rather widespread application in animal waste
odor evaluation.    In spite of its application, however, there are sev-
eral basic limitations to this approach.  Being a personal observation,
the sensitivity of the observer is highly important in determining the
values achieved with the instrument.  Although sniffing through the
scentometer with  the odorous air ports closed is designed to restore
normal sensitivity to the observer, complete restoration of  the smell
sensitivity may not occur rapidly  enough  to obtain meaningful results.
The  charcoal bed  can become saturated and not give a  complete odor re-
moval from  the air breathed when all the  ports are closed.   Since there
is no indicator to show  the carbon is saturated, misleading  results may
be obtained under these  conditions.  Intermittent odors which are common
in animal waste,  particularly when observations are made some distance
from the odorous  source, present additional difficulties and require use
of the scentometer over  a considerable period to get  representative data.
In spite of these limitations, however,  the scentometer is a useful de-
vice and is being used by some  regulatory agencies.

ODOR QUALITY

In contrast to odor strength, which  can be quantitatively evaluated,  there
is no straight forward  technique  to  quantify  odor  quality.   Most  frequently,
odor quality  is described by  comparison  to some common odorant with which
the  reader  or listener  is  familiar or  to a sensation with which he  is

                                        69

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                                    OT
familiar.  For example, White et_ a^.   used the following terms  to describe
the odorous components of dairy waste:  foul, sweetish, acetate,  nutlike,
pungent, and musty.  In describing the odor of the various fractions  of
                            35
poultry manure odor, Burnett   used the following words:  rotten egg,  rot-
ten cabbage, onion-like, putrid, butter-like and garlic.

An alternative method  to evaluate odor quality was used by Sobel.     He  ask-
ed a panel of odor evaluators to select a number from one to 10  indicating
the degree of offensiveness of the samples.  A nonoffensive odor was  mark-
ed as zero, a very strong offensive odor was ranked as 10, a definite offen-
sive odor was six and  a faint offensive odor was four.  He also  asked panel
members  to select suitable descriptors from the following list to describe
the odor of the  sample:  mold, musty, fish, stagnant water, sulfide,  rot-
ten egg, petroleum,  earth, yeast, ammonia, grain, feed, sour, fermented
and cabbage.  Using  this approach, he was successful in differentiating
the offensiveness of an odor and the odor strength.
                                        70

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                                    SECTION X

                     FECAL ODOR AS AFFECTED BY FEED ADDITIVES

The effects of various feed additives on swine fecal odor were studied in
three feeding trials at Texas Tech University by Ingram et al.    In each
trial, pigs were assigned to five treatments, three replications or pens
per treatment with four or five pigs per replicate.  Fecal samples were
composited from any three of the pigs in each replication and immediately
evaluated by olfactory panels in trials one and two and by panels and column
chromatographic analyses in trial three.  Gas-liquid separation was a quali-
tative measurement of primarily the organic amines, skatole and indole.
Composition of the basal diet is shown in Table 23.

                                                                    72
Table 23.  COMPOSITION OF BASAL DIET FOR ANIMALS ON FECAL ODOR STUDY

       Ingredient                             Percent, air-dry
       Grain sorghum                                66.0
       Soybean meal (44%)                           30.0
       Salt                                          0.5
       Defuor.  phosphate                            1.5
       CaC03                                         0.5
       Premix (vitamin-mineral)                      1.5
Treatments for trial one and the  results  are shown in Table 24.  The feeding
period was 14 days duration, using  four-week-old-pigs.  The treatments were
basal; dry Lactobacillus acidophilus  in a wheat bran carrier and mixed into
two feedings per day of five g  each;  lyophilized yeast culture at five per-
cent of the diet, replacing grain sorghum; L_. acidophilus cultured in whole
milk with an average of 2.9 x  10    viable cells per ml and mixed into the
feed twice daily at the rate of 175 ml each time; and last, activated char-
coal at five percent of the diet, replacing grain sorghum.  Two panels of  11
participants and 31 participants  scored the fecal samples for volatile
matter on a scale of one through  10,  one  being not objectionable through 10,
extremely objectionable.
                                       71

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 Table 24.   TREATMENTS AND RESULTS - TRIAL  1.   TEXAS TECH UNIVERSITY
            SWINE FECAL ODOR STUDY72
      Treatment                                  Odor score

      Basal                                         7.6
      Dry lacto (10 g)                               7.5
      Yeast (5%)                                     7.4
      Wet lacto (350 ml)                             7.2
      Charcoal (5%)                                 6.7
 Orthogonal mean comparisons resulted in a significant difference between
 the basal and dry lacto treatments  versus five percent charcoal in re-
 duction of volatile matter.

 Table 25 shows treatments and results for trial two.  The feeding period
 was 10 days in length and the pigs  from trial one were rerandomized for
 the second trial.  Olfactory observations were made by two panels of 23
 and 27 participants.  There were no significant differences among the treat-
 ment means.
 Table 25.   TREATMENTS AND RESULTS  -TRIAL 2.  TEXAS TECH UNIVERSITY SWINE
            FECAL ODOR STUDY
     Treatment                                 Odor score

     Basal                                         6.5
     Sagebrush (5%)                                6.3
     Wet  lacto (300 ml)                            6.3
     Whole milk  (300 ml)                           6.2
     Charcoal  + Wet lacto                          5.9
Table 26 summarizes treatments  and  olfactory panel results for trial three.
Three panels of 60 participants  each evaluated  fecal samples for trial three.
The feeding period lasted 21 days and used four-week-old pigs.

                                      72

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Table 26.  TREATMENTS AND RESULTS - TRIAL 3.  TEXAS TECH UNIVERSITY SWINE
           FECAL ODOR STUDY72
    Treatment                                    Odor score

    Basal                                           6.5
    Wet lacto (300 ml)                              6.5
    Charcoal (2%)                                   6.8
    Yeast (2%)                                       6.5
    Dry lacto (10 g)                                6.7


No significant mean differences were detected by the olfactory panel.  Fecal
samples in trial three also were used for some gas chromatographic analy-
ses.  A sample of air from just above the feces was used.

By the end of the second week, as shown in Table 27, chroma tographic analy-
ses indicated a marked reduction in volatile matter of feces for the yeast
and dry lacto treatments.
Table 27.  CHROMATOGRAPHIC RESULTS AFTER 2 WEEKS - TRIAL 3:  TEXAS TECH
           UNIVERSITY SWINE FECAL ODOR STUDY 2
Treatment
Basal
Wet lacto (300 ml)
Charcoal (2%)
Yeast (2%)
Dry lacto (10 g)
Peak Height Ratio
1.00
0.83
0.95
0.28
0.07
% Reduction
—
17
5
72
93
  The  peak-height  ratio was  used as  a comparison between each treatment and
 the basal  diet -  involving  measurement  of  the height of each peak on the
 chromatogram and  then using peak height as the denominator.  The percent
 reduction  indicates  the  decrease in volatile matter for each dietary treat-
 ment  as  compared  to  the  basal diet.

                                       73

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Table 28 indicates the percent reduction in volatile matter of the  feces
from pigs in trial 3 after 21 days of feeding.

Table 28.  CHROMATOGRAPHIC RESULTS AFTER 3 WEEKS - TRIAL  3;  TEXAS  TECH
                                            72
           UNIVERSITY SWINE FECAL ODOR STUDY
Treatment
Basal
Wet lacto (300 ml)
Charcoal (2%)
Yeast (2%)
Dry lacto (10 g)
Peak height ratio
1.00
0.61
0.72
0.07
0.003
% Reduction
—
39
28
93
99
Results indicate a  significant  reduction in volatile matter between the
basal treatment versus  the yeast  and dry lacto treatments.  The volatile
                                                 72
matter detected was primarily skatole and indole.

In summary,  these data  indicate that a lyophilyzed yeast culture and a
commercial preparation  of Lactobacillus acidophilus reduced the skatole
and indole content  of feces of  young pigs, but that the changes in vola-
tile matter  content were not detected by olfactory panelists.

                                                              73
Based upon limited  feeding trials at Colorado State University,  sagebrush,
as a feed additive, was reportedly effective  in  reducing  feedlot odor.
The effectiveness was attributed to the volatile oils being carried through
to the manure.
                                       74

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                 CHEMICAL TREATMENT OF MANURE TO CONTROL ODORS

Several investigators have sought a procedure whereby some relatively
inexpensive chemical could be added to manure to achieve odor control.
One technique has been to add a chemical or mixture of chemicals which
will halt anaerobic decomposition.  A second approach, to gain temporary
odor control, is to oxidize the odorous compounds present in a slurry.
Although they will be replaced with continued decomposition, this may al-
low time for the manure to be applied to cropland or otherwise moved so
that odors are not critical.

CHLORINE AND LIME

   74
Day   evaluated chlorine and lime as possible means to deodorize liquid
hog manure.  In these tests, the chemicals were added to manure storage
tanks as the manure accumulated.  It was determined that the daily chlorine
demand of hog manure was 50 g per 50 kg (0.1 Ib per 100 Ib) pig.  When a
pit was treated at this rate, odor was eliminated and when the solids were
dewatered on a sand bed, they, too, were odorless.  This amount of chlorine
was costly (63 cents per hog/month), however, and the method was not pur-
sued.  In a similar study, lime was added  to the manure to raise the pH to
11.  Whenever the pH dropped to nine, more lime was added.  The lime treat-
ment was also effective in eliminating odors by inactivating anaerobic bac-
teria.  The daily lime requirement was reported as 80 g per 50 kg (0.16 Ib
per 100 Ib) pig.  The lime treatment, although less expensive than chlorine,
was estimated as 10 cents per hog per month  and increased the quantity of
solids to be handled.

Hydrated lime, added to manure in amounts  between five and 20 percent, was
found to effectively deodorize poultry manure and to materially reduce the
nitrogen loss upon storage, according to a study by Yushok and Bear.
They suggested that since most soil would  benefit by additional lime, the
cost of the lime required for deodorization  could be charged against the soil
on which the manure was to be applied and  not be a direct cost to odor control,

                                      75

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 The addition of sodium hydroxide to liquid poultry manure at a concentra-
 tion of 0.9 percent was effective in preventing the development of objec-
 tionable odors according to Benham.    This treatment  also resulted in  a
 reduction in the number of total aerobic bacteria and  coliforms.   The
 application of the equivalent of 23 cu m (6,000 gal.)  of  poultry manure
 containing this concentration of sodium hydroxide/acre of grassland was
 not found to produce harmful effects on the grasses studied.   The  cost  per
 bird per month was estimated to be in the range of one to two  cents.  Thus,
 it would cost $3,000 to $6,000 annually for a 25,000 layer operation to use
 sodium hydroxide for odor control according to this study.

 POTASSIUM PEBMANGANATE
 Potassium permanganate (KMnO,) is a powerful  oxidizing agent, in  part be-
 cause of its ability to undergo several different  reaction paths.  Perman-
 ganate (MnO^ ) solutions are most effective as  oxidizing agents  (and,
 therefore, in odor control) in acid solution, next in alkaline solution,
 and least effective in neutral solution.

 Three different oxidation reactions can take  place, depending on  the pH
 of the solution:

 In strong acid (pH < 2):   MaO ~ + 8H+ 4- 5e~ -*• Mh*"4" + 4H20

 In "more neutral solutions"
    (pH 3-11)                  Mn04~ + 4H + 3e~ +  Mn02 + 2H.O

 In strongly alkaline solutions
    (pH 11)                       ^in°et~ + e~ ->  Mn04~

 The most  effective reaction, in a practical sense, is the second  of the
 above  because  the solutions are essentially noncorrosive.  For all three
 reactions,  the  reaction rate will increase with increasing temperature,
with increasing KMhO,  concentration,  and with increasing concentration  of
 oxidizable  impurities.  Also, the rate  of reaction increases as  the pH
varies  from neutral  in  either direction.

                                      76

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Potassium permanganate has been suggested for odor control around livestock
production facilities since 1964 when its use was reported by Faith.     The
oxidizing capabilities of potassium permanganate when used in gas-scrubbing
                                               78
devices were documented by Posselt and Reidies.    In their studies,  air
containing various odorants was passed through a pair of gas-washing bottles
in parallel.  One gas-washing bottle contained a one percent solution of
potassium permanganate at a pH of 8.5; the other bottle contained distilled
water at a similar pH.  Under these conditions, they compared the threshold
odor numbers of the effluents from the two bottles when various odorous or-
ganic compounds were being passed through the solutions.  They evaluated the
use of potassium permanganate for the oxidation of various mercaptans, other
sulfur-containing compounds, amines, phenols and other organic odorants.  In
each case they found significant reduction in the threshold odor number was
achieved by passing the gases through potassium permanganate compared to pass-
ing them through distilled water.  Potassium permanganate is being marketed
by Carus Chemical company for use in odor control applications (See Appendix  A

HYDROGEN PEROXIDE

The use of hydrogen peroxide has been proposed for various waste treatment
applications.  Hydrogen peroxide (H_02)  is commercially available as an
aqueous solution ranging from three percent for use as a disinfectant in
first aid up to 98 percent solutions.  Its primary application is as an
oxidizing agent.  Hydrogen peroxide decomposes to form water, molecular
oxygen, and an accompanying release of heat.  Strong solutions, greater than
eight percent H-0_, are considered corrosive and must be handled in special-
ly selected materials,

Dairy manure
The use of hydrogen peroxide for the treatment of dairy cow manure was des-
                                 79
cribed in a report by Hollenbach.    In  the first trial, 19 1  (5.0 gal.)
of 50 percent hydrogen peroxide were diluted and pumped at the rate of 2 1
(1/2 gal.) per minute into liquid manure tanks while the circulating pump
was used to provide mixing and circulation of  the entire 89 cu m (24,000 gal.)
of manure in the system.  Sufficient hydrogen peroxide was added to provide
a total concentration of  100 ppm in the  mass.  Their notes were as follows:
                                       77

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prior to agitation and hydrogen peroxide addition,  a pleasant  silage  or
animal type odor emanated from the vent and no  hydrogen  sulfide was de-
tected.  Immediately upon agitation the sulfide concentration  rose to
150 ppm and a strong sulfide odor was evident.   Within 30 minutes, when
about half the hydrogen peroxide had been added, the sulfide concentra-
tion in the air dropped markedly and most of the odor had disappeared.
After one hour, when the full 100 ppm of hydrogen peroxide had been
added, no sulfide was detected and only a moderate  ammonia odor remained.
When the agitation was discontinued for 18 hours and then resumed, the
hydrogen sulfide level and the gases were at the initial level before
the hydrogen peroxide addition.  Thus, the hydrogen peroxide was,  in  their
view,  a temporary but effective odor control technique under  these conditions.

In a second  trial, Hollenbach 9 added hydrogen peroxide  as  in the earlier
trial  but  immediately thereafter added a second similar  quantity.  He
found  the  additional hydrogen peroxide resulted in  a further  decrease in
the odor of  the manure storage pits.  Sixteen hours later,  the sulfide
concentration  had risen  and was similar to that prior to treatment.   Some
foaming difficulties were also reported during  the second trial when the
larger peroxide additions were made.  Hollenbach felt this  foaming could
be prevented by adding a less concentrated peroxide solution.  At the
100 ppm concentration used in the  test about 6.0 1  (1.7 gal.) of 50  percent
hydrogen peroxide at  a cost of about  $3.90 would be required to eliminate
the sulfide  type  odors from a 37.8 cu m  (10,000 gal.) manure storage tank.

In a study to  test the effectiveness  of  hydrogen peroxide in treating
                                   80
dairy  cattle manure odors, O'Neill   used hydrogen peroxide at concentra-
tions  of 10  and 15 percent, adding sufficient  hydrogen  peroxide to pro-
vide 50 to 220 ppm.  When hydrogen peroxide was added at 50 ppm, the
odor improvement was  only limited.  The sulfurous  odors were  removed but
strong animal  and ammoniacal odors were apparent.   With the  100 ppm
treatment, the strong animal odor was replaced by  a strong silage odor
with vestiges  of  ammonia.  Using 125 ppm, only a silage odor  was evidenced.
Sulfides were  determined at levels greater than five ppm in  the manure
slurry before  treatment  but were reduced to zero by the hydrogen peroxide
                                       78

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treatments at levels greater than 100 ppm.  No foaming problems were en-
countered during these evaluations.

Swine manure
The use of hydrogen peroxide for the control of swine manure odors was des-
                            80
cribed in a report by O'Neil.  In this study, pig manure slurry was treat-
ed with 10 percent hydrogen peroxide at levels of 115 and 275 ppm.  The
hydrogen peroxide was fed into the open end of the discharge pipe as the
manure was pumped from a holding pit into a 5.3 cu m (1,400 gal.) liquid
manure tank.  Hydrogen sulfide levels were reduced to zero in the gas
over the manure slurry under both test conditions.  The investigator, how-
ever, thought that superior odor control was obtained using the 115 ppm
dosage.  The reason for this increased effectiveness was judged to be
primarily because of the effective mixing that took place in that trial.
Atmospheric hydrogen sulfide was at a level of 10 ppm for the holding tank
but was reduced to zero in the tank spreader after treatment.

Poultry manure
                                                           81
Field trials were conducted by Kibbel, Raleigh and Shepherd   at  a large
poultry farm that regularly received complaints from neighbors about the
extremely foul and unpleasant odor when chicken manure slurry was spread
on the fields.  Sufficient hydrogen peroxide to attain levels of  100,
150  and 175 ppm based on total slurry weight was  added to the discharge
side of a pump used to transfer a  five percent to 10 percent solids  slur-
ry from the collection pit under the birds  to a 5.3 cu m  (1,400 gal.)
tank truck equipped to field spread the manure promptly for its plant
nutrient values.  An area 3 m  (10  ft) wide  and 400 m  (0.25 mile)  in
length was used for manure application from each  level of hydrogen  per-
oxide  treatment.  Each test strip was separated from  the  adjacent test
zones by  30 m  (100 ft).  The farm manager and two Extension Service  repre-
sentatives  from Pennsylvania State University determined  the overall qual-
ity  and type of odor by sense  of smell.   Hydrogen sulfide specifically was
determined  quantitatively with a Hach  test  apparatus.  Additional checks
were made 18 hours later to  determine  the efficiency  and  persistence of
the  treatments.

                                       79

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All three hydrogen peroxide levels of 100,  150  and 175  ppm  virtually
eliminated the presence of hydrogen sulfide and reduced the odor of the
chicken manure significantly.  No differentiation could be  made among
the manures treated with the several hydrogen peroxide  levels.   The offen-
sive chicken manure odor remained significantly reduced in  the  test plots
compared to the control (non-treated) plots on  the second and  third day
after application.

PARAFORMALDEHYDE

The use of flaked paraformaldehyde for the treatment of animal waste to
control odors was studied  by Seltzer, Mourn and Goldhaft.    Paraformalde-
hyde is a mixture of  polyoxymethylene glycols containing 90-99 percent
polymerized formaldehyde and is  available as powder, granules or flakes.
Its chemical  formula  is HOH^O-GH^-O^OH.  It is very slowly soluble
in cold water.

Paraformaldehyde liberates formaldehyde gas  as it decomposes.   The flake
form  liberates  the gas most slowly of the various available forms.   The
loss  rate of  paraformaldehyde  is affected by temperature as indicated in
Table 29.   The rate of paraformaldehyde decomposition  is also  increased

Table 29.   PERCENT WEIGHT LOSS OF FLAKE PARAFORMALDEHYDE WHEN  EXPOSED TO
                                                    82
            AMMONIA-FREE AIR AT VARIOUS TEMPERATURES
Time
1 day
2 days
3 days
4 days
1 week
2 weeks
3 weeks
4 weeks
5 weeks
6 weeks
5° C
0.09
1.2
1.8
2.2
2.7
3.0
22° C
1.3
2.8
4.6
6.7
13.3
22.2
28.9
31.9
34.0
37.8
38°C
3.1
6.5
10.2
13.5
26.2
34.5
39.8
42.8
46.0
48.8
                                       80

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by the presence of ammonia as is indicated in Table 30.  The reaction of
formaldehyde with ammonia gas occurs as follows:
                    6 CH_0 + 4 NH. -> C.H..N. + 6 H.O           (24)
                        /        j    D \.L 4      {.
Table 30.  PERCENT WEIGHT LOSS OF  FLAKE PARAFORMALDEHYDE IN PRESENCE OF
                                                   Q r\
           AMMONIA GAS FROM CHICKEN MANURE AT 22  C
Days
on test
1
2
3
4
7



0,5 g para-
formaldehyde
over 100 g
manure
13.1
37.1
48.8
77.1
Residue iden-
tified as hex-
amethylene
tetramine
1 g para-
formaldehyde
over 100 g
manure
5.2
19.7
33.7
38.3
58.1



'3 g para-
formaldehyde
over 100 g
manure
0.7
5.9
15.1
21.2
27.1



1 g para-
formaldehyde
over no ma-
nure
3.1

5.4
6.0
8.9



At ordinary temperatures this reaction  is  rapid  and proceeds  to completion.
The end product of the reaction, hexamethylene tetramine,  is  a white, pow-
dery, odorless material.

To test the effectiveness of paraformaldehyde in controlling  poultry ma-
                         QO
nure odor, Setlzer ejt al.    prepared six  3.8 1  (1.0 gal.) plastic bottles by
adding 100 grams of feces to each.   Ten ml of water also were added to
each bottle to provide adequate moisture.   Paraformaldehyde flakes were
added to the bottles in the amounts  of  0.5-7-.0 g.  The pH  of  the  air over
the manure was measured as an indication of the  ammonia content.  Results
of this experiment are shown in Table 31.

After 12 days of this experiment a 1.0  g   manure sample  was  removed from
each of the test bottles and subjected  to  bacterial counting  on brain heart
infusion agar.  Plates were incubated at 37° C for four days  and  the counts
shown in Table 32 were obtained.  As part  of this test, the manure was also
                                       81

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Table 31.  AMMONIA CONTENT (PPM)  OF HEADSPACE GAS  OVER 100  GRAMS OF
           CHICKEN MANURE TREATED WITH VARIOUS LEVELS  OF PARAFORMALDEHYDE
                            82
Days on test
1
2
5
7
9
14
21
28

0

100
100
100
100
100
100
100
Quantity
0.5
0
1
10
50
100
100
100
100
of paraformaldehyde added
1
0
0
1
10
100
100
100
100
3
0
0
0
0
0
0
0
0
5
0
0
0
0
0
0
0
0
> 8
7
0
0
0
0
0
0
0
0
Table 32.  BACTERIAL COUNTS OF MANURE SAMPLES ON BRAIN HEART INFUSION AGAR
           AFTER  11 DAYS OF EXPOSURE TO VARIOUS QUANTITIES OF PARAFORMALDE-
           HYDE82
  Quantity of paraformaldehyde added
          per 100  g manure,  g
Number of organisms per g
        of manure
                  0
                  1
                  3
                  7
       2.2 x 10'
      1.64 x 10
         1 x 10:
           0
8
analyzed  for nitrogen concentration.   It was  found that the paraformalde-
hyde had  been  effective  in reducing nitrogen  loss.  The Kjeldahl nitrogen
concentration  in  the  untreated samples was  1.39 percent.  That in the
bottle  containing three  percent paraformaldehyde  contained  1.75 percent.
Paraformaldehyde,  when used as a manure  additive, was indicated by these
tests to  be  effective in reducing the evolution of both ammonia and
hydrogen  sulfide.   In addition, it tended  to  reduce the number of viable
bacteria  within the sample.  Among the limitations of paraformaldehyde
is its  toxicity to animals if they ingest more than the toxic dose.  In
addition,  formaldehyde as evolved from the  flakes has an  odor itself.
                                       82

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Paraformaldehyde flakes are sold under the brand name Methogen by Vineland
Laboratories of Vineland, New Jersey.
                                       83

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                                  SECTION XII

                     USE OF SOIL FILTERS TO REMOVE ODORANTS
                                                                         QO
The use of soil beds for odor control was reported by Carlson and Leiser.
Their tests indicated that odor reduction was affected by microorganisms
in the soil rather than by ion exchange, chemical combination or oxidation.
Moist loam soils were found to have the greatest odor removal possibili-
ties.  Over a three-month test period, hydrogen sulfide gas concentrations
of 15 ppm at a flow rate of 107 1 per min per sq m (0.35 cu ft per min per
sq ft) of soil surface were reduced to an imperceptible level in 81 cm
(32 in.) of soil.  For a flow rate of 103 1 per min per sq m (0.34 cu ft per
min per sq ft) and a hydrogen sulfide concentration of 9.5 ppm, 90 percent
of the hydrogen sulfide was removed in the first 46 cm (18 in.) of soil.
Effectiveness of the soil beds in removing the hydrogen sulfide did not
diminish during a three-month test period.  A soil filter for the removal
of odors from a Mercer Island pumping station in Washington has been in
successful operation for three years.

                                                         84
As an outgrowth of the earlier work, Carlson and Gumerman   proposed a
system for the treatment of odorous gases.  Their system included a per-
forated tile system through which the odorous gases were blown.  Above
the tile system the soil was covered with a greenhouse to facilitate year-
round plant growth.  The role of the plants within the system was to keep
the structure open, to utilize some of  the excess sulfur, and to replenish
the soil organic matter that is sacrificed in the active biological growth
which occurs.  They suggested a plant with a shallow  root system which
would meet the above goals but not  interfere with the gas distribution
piping system.

Investigating soil columns as a means of  removing odor, Gumerman and
        rt c
Carlson    proposed a two-stage process:   an absorption and a rejuvenation.
The  rejuvenation or oxidation stage  requires the presence of oxygen.  In
designing  a soil column  for  the  absorption of H_S, they listed  the follow-
ing  considerations:

                                      85

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 (a)   Detention time
 (b)   Temperature
 (c)   Quantity of EJ5
 (d)   Initial H-S concentration
 (e)   Gas flow rate

 Hydrogen sulfide was  removed by both wet and  dry soil columns.  For the
 wet  columns, absorption seemed to be the responsible mechanism.  Better
 removals were obtained at pH 8 than at either pH 4.0 or 5.8, suggesting
 that the  hydrosulfide ion HS, not H_S, is  the active specie.  Removal
                                   2+    3+    2+       2+
 was  enhanced by the presence of Cu  , Fe  , Zn   and Ni   ions at the
 soil surface.

 Hydrogen sulfide removals were more efficient in dry than in wet soils.
 The  dry soil reactions were postulated to be  a two-stage surface catalyz-
 ed process.

       H0S removal:      M0_ + H9S •* MSV + H_0               (25)
        .&                  A.    Z      A    2.
                         MO  is the cation oxide present at the removal site
                           A.
      Rejuvenation:      2 MSX + XH20 •> 2MOX -I- Sulfur         (26)

 The  limitation on the number of possible rejuvenations is caused by the
 steric hindrance from deposition of sulfur  at the  removal site.  The same
 metal ions as listed  for the wet soil system  are desirable for the dry
   *   85
 system.

 The  use of soil filters for the removal of  animal  waste odors was investi-
                              27
 gated by Burnett and  Dondero.    They based their  initial trials on the
                                   go                        oc
 earlier work of Carlson and Leiser   and Gumerman  and Carlson   and found
 that,  indeed, the use of soil columns was effective in removing both hy-
 drogen sulfide and ammonia from the head-space gas over decomposing poultry
manure.   They found that for ammonia concentrations of up to 200 ppm, re-
movals  of 100 percent were obtained and for hydrogen sulfide concentrations
 of 22  to 100 ppm more than 95 percent removal occured throughout a three-
month,  continuous testing period.   They further  found that when the soil
                                       86

-------
columns dried, the ammonia removal efficiency dropped rapidly.   Thus,  to
be fully effective, the moisture content of the soil must be maintained.
By mixing manure with the soil prior to using it in the column, the mois-
ture-holding capacity was increased.  As a result of their work they made
some tentative suggestions as to the area required for odor removal.
Assuming a 40,000-layer operation, they suggested that a trench 0.61 m
(2.0 ft) deep, 0.61 m (2.0 ft) wide and 276 m (903 ft) long would be re-
quired to deodorize the air.  This is equivalent to 2.55 1 (0.0903 cu ft)
of soil per bird.

                                            27
As a part of this study, Burnett and Dondero   attempted to determine the
pressures required to force air through the soil columns at various depths.
The columns they were using were 15 cm  (6.0 in.) diameter plexiglass with
a shallow layer of gravel just above the gas inlet.  For untreated  soil
they were using, a back pressure of 13  cm  (5.0 in.) of water was sufficient
to cause 30 1  (1.1 cu ft) per min  of air to pass through a 0.61 m  (24 in.)
depth of soil.  For the soils to which  some manure had previously been
added,  this pressure was reduced to approximately 6.4 cm  (2.5  in.)  of
water under the same conditions.   Thus, one may  expect wide variations  in
the pressures  required to gain  the necessary volumetric  gas flow.
                                       87

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                                 SECTION XIII

                   USE OF PROPRIETARY ODOR CONTROL CHEMICALS

When two odorants are mixed the resultant has a different odor from that
of the original components, even though no chemical reaction may take
place.  When the odor of the mixture is more pleasant than that of
one of its components, the process may be considered to be a method of
odor control by which an unpleasant odor (malodor) is mixed with another
substance (controlling agent).  Such processes are called odor cqunter-
action, odor masking, odor cancellation, odor neutralization or reodoriza-
tion.  The specific meanings of some of these terms are discussed below.

The literature contains early reference to "odor pairs", odorous gases in
proportions that make the mixture odorless or nearly odorless; for example,
rubber and cedarwood, musk and butter almond, skatole and coumarin, and
butyric acid and oil of juniper.  These original odor measurements were
dilution-to-threshold ratios and the reduction in  these values resulting
from mixing a malodor with a controlling agent is  called "odor counter-
action".  Odor counteraction is considered to be the phenomenon whereby
odor intensity, however measured, is reduced by adding a non-chemically-
reactive  controlling agent to a malodor.

The term  "odor cancellation" implies complete counteraction or reduction to
an odorless condition.  "Odor neutralization" is also used  in this sense,
although  the chemical implication of this term  (as in acid-base neutrali-
zation) may be confusing.  No generally  accepted physiological mechanism
explains  this phenomenon;  some  investigators question its reality.   In the
absence of a generally accepted scale of  odor intensity, it is difficult
to say what "nearly  odorless" really means.

When  a malodor is  changed  in  quality by  mixing with  a control agent,
especially when  the  change is so  extreme  that the  malodor is rendered
unrecognizable,  the  process  is  called  "odor  masking".  To the extent that
masking makes  a  malodor  less  objectionable,  it  is  a  method  of odor con-
trol.  Odor  control  by masking  and  by  counteraction  have similar  operational

                                        89

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requirements and are frequently indistinguishable from each other in
practice, even though their objectives are presumably different.

Several chemicals are available to livestock producers to control odor.
These chemicals, although seldom sold on the basis of composition but  on
the basis of brand names and specific company formulations, are generally
thought to behave in one of several ways.  Chemicals are sold which will
modify the pH or in some other way inhibit biological degradation. These
chemicals are thus designed to inhibit odorous gas formation.  A second
group of chemicals commonly called masking agents have a particular odor
of their own and are designed to overcome the manure odor with the odor
of the chemical additive.  Counteractants, as the name implies, are gen-
erally mixtures of aromatic oils selected to counteract the odor of the
components in the waste.  Another group, the deodorants, is a formulation
designed to eliminate the malodor of the waste generally without adding
an additional covering odor.  The final classification is the digestive
deodorant which is generally a combination of enzymes and aerobic and
anaerobic bacteria designed to modify the biological process of degrada-
tion in such a way as to alter the odorous compounds produced.

Deibel   performed odor abatement studies on liquid poultry waste using
a number of chemicals and proprietary compounds.  Additions of sodium
chloride up to eight percent  (weight/volume) or of commercially available
powdered bacterial starter  cultures  (digestive deodorants) to the waste
as well as direct ozone treatment failed to abate the odor.  Addition of
lime abated the odor for seven to 10 days, but after one week, the strong
odor of ammonia was readily detected regardless of the  lime concentration.
The addition of hypochlorite to  the waste caused the evolution of chlorine
gas, presumably from the reaction of the hypochlorite and  uric acid.   The
addition of 50 ppm of chloramine-T rapidly deodorized the  manure, but the
odor returned within 24 hours.   The  cost of treating  the waste with chlor-
amine-T immediately prior to removal and spreading of the  manure was com-
puted to be $5,000 annually for  a 25,000-bird operation.

                     86
A report from England   regarding the addition of odor  control compounds
to liquid poultry manure indicated that good odor control  could be achieved
                                       90

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by the use of the commercial masking agent added directly to the manure
slurry at the rate of 25 to 50 ml per cu m (one to two pints per 10,000 gal.)
prior to spreading.  Costs for such treatment were estimated at three to
                                                                      O/:
nine cents per cu m  ($1.20 to $3.60 per 10,000 gal.) of liquid manure.
                                            Q/1
A study was conducted by Burnett and Dondero   in which a variety of mask-
ing agents, counteractants, deodorants, and digestive deodorants were
evaluated - first in a laboratory study,  then in a field operation - to
determine their effectiveness.  Odor panels were used to evaluate the simi-
larity of the odor of treated manure samples receiving various concentra-
tions of the odor chemicals.  For evaluation of the  chemical counteractants,
the deodorants, and masking agents, 500 ml of the waste was placed in a
screw cap quart jar.  Each jar then received a quantity of  the chemical
being tested.  The quantities ranged from zero to  3.2 g of  the appropriate
chemical per jar.  For the evaluation  of  the digestive deodorants, which
required an incubation period for action  to take place, the waste sample
was placed in the jars,  the chemical added, and  then the material allowed
to  incubate at room  temperature  for 28 hours.  A sample was withdrawn  and
placed in the test vial.

Data were collected  in  terms  of  an  index  of  similarity  (D). This index is  de-
fined as the square  root of the  sum of the squared differences between the
panel ratings for  the nine  concentrations of  chemical and  the  control.  Thus,
the D index was  a measure of  the effectiveness  of  the odor control  chemicals.
A low value  indicated lack  of effectiveness  and a  high  index meant  the treated
liquid manure was highly dissimilar to untreated liquid manure.  Their results
 indicated  that some  chemicals were  effective  in controlling the  odors immedi-
ately after  addition to the waste.   This  would be  equivalent  to  adding odor
 control  chemical to  a storage pit immediately before spreading the  waste  on
 cropland.  The masking  agents and counteractants were found to be most effec-
 tive  odor  control  products,  deodorants were moderately effective, and diges-
 tive  deodorants  were least effective.   The cost of treating liquid  poultry
manure with  an effective animal odor control product (masking agent)  was
 estimated to be 37 cents per cu m ($14.00 per 10,000 gal.) of liquid ma-
 nure based upon brief field study.   A list of odor control product  manu-
 facturers  was included in their report.  That list is given in Table 33,
                                       91

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   along with additions which have become available since then.


   Table 33.   MANUFACTURERS  OF ODOR  CONTROL PRODUCTS FOR USE IN CONTROLLING

              MANURE ODORS 36'87
 Agriaids,  Inc.
 Div.  of Flavor  Corp.
   of  America
 3037  N.  Clark St.
 Chicago, 111. 60657

 Airkem,  Inc.
 P.O.  Box 203
 Commerce Rd.
 Carlstadt, N.J.  07072

 Albert  Verley & Co.
 124 Case Drive
 S. Plainfield,  N.J.
         07080

 Allied  Chemical Corp.
 Solvay  Process  Div.
 40 Rector  Street
 New York,  N.Y.  13209

 Blenders,  Inc.
 6964  Main  St.
 Lithonia,  Georgia

 Chloroben  Chem.  Corp.
 Belleville Turnpike
 Kearny, N.J.  07032

 Dodge & Olcott, Inc.
 P.O.  Box 273
 Old Chelsea Sta.
 New York,  N.Y.  10011

 Florasynth, Inc.
 900 Van Nest  Ave.
 P.O.  Box 12
 Bronx,  N.Y. 10462

 Fritzsche  Bro.,  Inc.
 76 Ninth Ave.
 New York,  N.Y.  10011

 Givaudan Corp.
 321 W.  44th St.
New York, N.Y.  10036

 Gland-0-Lac Co.
 19th  & Leavenworth
Omaha, Nebraska
International Flavors
 & Fragrances, Inc.
521 W 57th Street
New York, N.Y. 10019

Kalo Company, The
Quincy, 111. 62301

Martin Bio-Chem
710 E. Southern Ave.
Mesa, Arizona 85201

Miles Chemical Co.
1127 Myrtle St.
Elkhart, Ind.

Nilodor Co., The
60 E. 42nd Street
New York, N.Y. 10017

Noville Essential
 Oil Co., Inc.
1312 Fifth Street
North Bergen, N.J.
          07047

Orbis Products Corp.
475 Tenth Ave.
New York, N.Y. 10018

Perry Brothers, Inc.
61-12 32nd Ave.
Woodside, N.Y. 11377

Reliance Chem. Co.
P.O. Box 19343
Houston, Texas 77024

Rhodia,  Inc.
600 Madison Ave.
New York, N.Y. 10022

S.B. Penick & Co.
100 Church  St.
New York, N.Y. 10007

Sep-Ko Chemicals, Inc.
3900 Jackson St. N.E.
Minneapolis,  Minn.
            55421
Somis Chemical Co.
Somis, California

U.S. Gypsum Co.
300 W. Adams St.
Dept. 139
Chicago, Illinois

Vineland Labora-
  tories , Inc.
Vineland, N.J.
        08360
                                         92

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                                  SECTION XIV

                 WASTE MANAGEMENT TECHNIQUES TO MINIMIZE ODORS

Because of technical difficulties in odor measurement and the large num-
ber of variables involved, only limited data exist relating odor produc-
tion and specific manure handling techniques.  There has developed, how-
ever, an extensive collection of observations relating odors with waste
handling practices.  Most of these observations were made incidental to
other studies and thus are scattered throughout the total accumulated
literature.  An overview indicates that certain operations are most like-
ly to be sources of odor.

OPEN LOTS

Animals have traditionally been  raised outside  in much  of our country.
When raised in  a sufficiently  low density to allow a  vegetative  ground
 cover  to be maintained,  little odor  was produced.  The  manure was  widely
 dispersed  and  during  warm weather dried rapidly.   Odorous  compounds that
 were  released  were diluted  sufficiently to avoid  odor problems.   Nutrients
 in the urine  and feces were incorporated into the soil resulting in a
 labor-,  odor-  and pollution-free manure management system.

 Increased animal density,  as found in cattle feedlots, hog lots and some
 poultry operations, results in eliminating the vegetative ground cover
 and the advent of manure management.  The water pollution potential of
 such operations has been well documented and need not be of concern in
 this report.   The odor potential of outdoor confinement units is largely
 related to manure management, but the operator has definite limits because
 of climatic and geographical limitations.  When  the manure accumulated on
 the soil  surface is wet (70 percent moisture or  above) anaerobic decompo-
 sition is possible.  When the manure  is both wet and warm, anaerobic bac-
 teria flourish, and  odors are likely  to  occur.   Coupled with  odor  release
 from  the  lot  surface is the tendency  of  animals  to lie or roll  in  the wet
 manure for its  cooling  effect.   A manure-covered animal perhaps represents
 the epitome of odor  generation  because heat of the animal stimulates  bac-
 terial metabolism.
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Site selection and facility design are of paramount importance in con-
trolling odors of this type.  Good drainage and proper orientation to
achieve the maximum drying rate are important.  Feedlots  in areas of  the
country with low, summer rainfall have definite advantages  in this res-
pect.  Adequate slope is also helpful in maintaining a dry  lot.   Slopes
of four to six percent are generally preferred for unsurfaced lots.   Con-
crete-surfaced lots may have a lesser slope and still be  satisfactory.
The use of concrete pavement around feeders and waterers  in areas of
heavy animal usage also can be helpful in promoting a dry lot.  Mounds
are frequently used to provide animals a dry place to lie down if drain-
age is marginal.

An unroofed feeding pen can be operated in a manner to minimize the ex-
tent of anaerobic decomposition.  Regrading to eliminate  poor drainage
that develops  from animal  activity can speed manure drying  in those areas.
Prompt repair  of leaking waterers is another method.  Manure removal fre-
quency-has been suggested  as an odor control  technique but  is limited
during wet periods.   Odor  control chemicals have been used  by some oper-
ators but their  results are difficult to predict and chemicals are often
expensive.

Of greatest importance with respect to site selection is  proximity to other
commercial operations,  recreational areas  and homes.  Although no legally
defined distances exist beyond which odors of nuisance level will not
occur, separation is  of great value in achieving natural odor dilution.
Nuisances have been established in courts  at  distances of  300 m  (1,000  ft)
downwind from  operations where anaerobic storage  tanks were uncovered  and
vented to the  atmosphere.   Thus,  a 0.8 km  (0.5 mile)  separation  from resi-
dences is a desirable minimum.  Greater  distances  from communities, housing
developments,  commercial areas, parks or other  points  where  people are
likely to gather are  appropriate.

Visual screening, landscaping, or other  means to  eliminate the  suggestion
of a potential odor source are often helpful  in avoiding odor complaints.
The untidy appearance of a livestock operation  can be detrimental because

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of the subjective nature of odors and the fact that people are subject
to suggestion of odors.

In discussing techniques for the control of odors from cattle feedlots,
     88
Paine   described the odors as being due to the anaerobic decomposition
of manure on the feedlot surface.  Also listed as odor-contributing areas
were the retention basins used to collect feedlot runoff.  The key to
odor control was described in terms of controlling the oxygen and moisture
content of the organic materials which produced the odor.  Maintaining the
feedlot surface with an overall slope between 2.0 and 4.0 percent to remove
excess moisture from the pens and to prevent low spots which accumulate
moisture were suggested.  Mounds were recommended in flat feedlots which
otherwise would not provide adequate drainage or a dry,  clean spot for
animals to rest.  The addition of straw or other fibrous material was
suggested where better footing is required in wet manure and also to re-
duce the moisture content.  Sprinkling the feedlot surface during dry
weather was recommended to control dust and to increase  aerobic manure
decomposition.  Methods suggested for minimizing odors associated with
manure holding ponds included solids removal prior to allowing the water
to enter and the use of surface aeration equipment.  When manure must be
stockpiled prior to disposal, the use of long, narrow rows was suggested.
Such rows are compatible with available composting equipment and are help-
ful in the control of fires.

CONFINEMENT BUILDINGS

Confinement livestock production has many potential economic and labor
utilization advantages.  To capitalize on these advantages, a higher
degree of sophistication is required in planning, design, construction
and operation than when range or pasture production is utilized.  Odor
production is related to several aspects of the system and, therefore,
needs to be considered in  the overall planning process.  Just as in the
case  for unroofed systems, site selection and visual considerations are
of paramount  importance.
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ANIMAL-MANURE SEPARATION

The initial manure management operation which has an important influence
on odor production is separating the animal from its manure.   If manure
remains in the pen with animals, they will inevitably pick up a portion
of it on their bodies and increase the odor-generating surface.   The
warmth of their bodies contributes to the decomposition and an odorous
building results.  Several schemes have evolved for rapid separation of
animals and manure.

Among the most common are slatted floors and frequent-flushing,  solid-
floor systems.  Each of these concepts has worked satisfactorily and when
properly designed and operated  can provide clean animals.  Slatted floors
may be used  in the entire pen area or in a limited area, partially slatted.
Although more expensive, the totally slatted floors have more reliably pro-
vided clean  animals.  Flushing  systems are highly varied in their design,
ranging  from manual, daily hosing of the floor to automatically flushing
gutters  and  alleyways which are designed to promote defecation in the
flushed  area.

Caged poultry systems overcome  this problem by having the cages suspended
so that  droppings pass  immediately  through the cage floor to a storage or
drying area.  When poultry is raised in a floor system, the floor frequent-
ly serves  as  the  storage area.   Under this system the manure pack is man-
aged to limit the moisture level so  that anaerobic  decomposition does not
occur.  Litter is the frequent  aid  used to achieve  this end.

MANURE STORAGE

From a biological point  of view, hence  an  odor point  of view, storage of
manure cannot be  realistically  separated  from treatment.   In  liquid and
semisolid storage systems, biological  activity continues throughout the
storage period unless inhibited by  low  temperature  or some alternate bio-
logical restraint.  In  typical, manure  storage tanks, anaerobic decompo-
sition is continually in progress but  in  a container not specifically

                                      96

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                                              2
designed for that purpose.  For example, Miner  suggests that for an
anaerobic lagoon a volume of  12.5 1 per g (200 cu ft per Ib) of volatile
solids per day should be provided.  In a storage tank designed for swine
wastes, 30 days storage, 1.56 cu m of storage volume per kg of animal
(25 cu ft of storage volume per thousand pounds of animal) would retain
the waste.  This is equivalent to 0.26 1 per g (4.2 cu ft per Ib) of
volatile solids added per day.  Thus, it is consistent that the odor of
manure storage tanks is typical of overloaded lagoons or septic tanks.

Most odor complaints are related to manure storage and, thus, the great
majority of research data available concerns this source.  Of particular
concern are the gases and odors released upon agitation of a manure stor-
age tank.  When a storage tank beneath a slatted floor is agitated, ani-
mals over the tank are subject to high concentrations of gaseous products
of decomposition.  Animals have been killed under these conditions.

One step to reducing odors from manure storage tanks has been to locate
the tanks outside the building and to keep them  covered which inhibits
the escape of gases from the  liquid surface.  By having the storage tank
outside the building, hazards to the animals from gas release upon mixing
are reduced but the difficulty in getting manure into the  tank is in-
creased.

An additional method of reducing odor  from manure storage  tanks  is  to
reduce the storage period.  Both research and  field  observations indicate
the odor  intensity and offensiveness  increase with storage  period.

Inhibition of anaerobic metabolism  during storage can be  effectively used
to  reduce odors.  Among ways  to  accomplish  this  are:   (a)  adding sufficient
oxygen to maintain aerobic  conditions,  usually by  aeration;  (b)  reducing
the moisture  content  to  inhibit  degradation  (drying); and (c)  inhibition
of biological activity by chemical  means.

In  aeration  for odor  control, aerobic activity is  the main mode  of  de-
gradation.  Although  the gaseous by-products  of  aerobic degradation have

                                       97

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not been  as  extensively  studied as those from anaerobic treatment, they
are generally nonodorous  and, therefore, not objectionable.  The gases
are more  highly  oxidized in nature.  The most common aerobic storage de-
vice  in use  is the  oxidation ditch.  The design and operation of oxidation
ditches were
age devices.
                                2
ditches were described by Miner.   Aerated lagoons  also are aerated stor-
Drying manure  as  a means  of  reducing odors and volume has received wide-
spread application in  the poultry industry.  Basically, the cages are
suspended  over a  manure storage pit into which the droppings fall.  Suf-
ficient ventilation  is provided in the pit to dry the manure.   By follow-
ing  this procedure,  it is possible to obtain extended storage periods.
Diligent,  operator control is  required, however, to prevent water spills
or other extraneous  water from entering the pit and exceeding the drying
capacity of the ventilation  system.

Several attempts  have  been made to find chemicals that will prevent odor
production for addition to manure storage tanks.  These are treated in
considerable detail  in Section IX.  Thus far, none of the materials sug-
gested have been  fully satisfactory or at a price that was acceptable.

ANAEROBIC  LAGOONS

Anaerobic  lagoons have been  used in animal waste management systems for
the  last ten years.  Originally they were conceived as a treatment and
disposal device,  but it soon became evident that in all but the most arid
regions lagoons filled and the removal or discharge of effluent was neces-
sary.  Secondly,  it  was also determined that effluent from an anaerobic
lagoon was  not  of suitable quality to discharge to most streams and the
most acceptable alternative  was to apply the effluent to cropland.  Thus,
the  anaerobic  lagoon also must be regarded as having a primary storage
function and achieves  considerable solid breakdown to liquid during the
storage.   Because of this action, the lagoon effluent is generally more
amenable to  pumping  than  fresh manure and can,  therefore, be applied to
cropland using  conventional  irrigation equipment.
                                      98

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The odor of anaerobic lagoons has been, described throughout the range of
nonoffensive to highly offensive.  A primary cause of objectionable odors
from lagoons is organic overload.  When a lagoon contains a large concen-
tration of fresh manure which is high in easily decomposable organic
matter, the acid-forming bacteria proliferate and produce a large concen-
tration of odorous intermediates including organic acids.  The methane-
forming bacteria, whose role is to convert organic acids to methane, grow
less rapidly than the acid-forming group.  As long as this imbalance exists,
odorous compounds will accumulate in the water and some will escape to the
air.  If the imbalance is severe, the me thane-forming bacteria will be
inhibited in their growth and the odorous condition may persist.  Such
overloads may be the result of either faulty design, inadequate volume,
or poor management.  Overloads are particularly common in the spring when
the lagoon, which has been receiving manure all winter, finally warms
sufficiently for acid-forming bacteria to attack the accumulated manure.
Again, there is a rapid production of organic intermediates and an insuf-
ficient number of methane formers to utilize them.

The intensity and duration of objectionable odors from anaerobic lagoons
can be minimized by providing an adequate water volume so the spring
surge in organic acid concentration will be diluted.  Overloaded condi-
tions also are avoided by adding wastes frequently rather than in large
quantities at irregular intervals.  Parallel, rather than series, opera-
tion of multiple lagoons makes more uniform use of the lagoon available,
hence reducing the tendency to cause overload.

Even with good design and proper management, however, anaerobic lagoons
will still produce an odor.  Whether this odor production is acceptable
will depend upon other environmental factors such as the proximity to
neighbors and the general odor criteria of the area.
                                       99

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                                  SECTION XV


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       Permanganate 'solutions.   Ind.  Engin.  Chem.  Product Research and
       Development.   4(3) ;48-50, 1965.

 79  Hollenbach,  R.  C.  Manure Odor Abatement Using Hydrogen Peroxide.
                   mmunication.  FMC Corp.  Rep.  No. 5638-R.   Princeton,  New
                Communication.  FMC Corp.
       Jersey.  1971.

80   O'Neil  E  T.  Manure Odor Abatement with Hydrogen Peroxide.   Personal
       Co^unication.  FMC Corporation Report No.   4760-R.   Princeton,  New
       Jersey.  1972.

81   Kibbel  W. H., Jr., C. W. Raleigh, and J. A.  Shephard.   Hydrogen Per-
       oxide  for Pollution Control.  Proceedings of the 27th Purdue Indus-
       trial Waste Conference, Purdue University.   May 24,  1972.

82   Seltzer  W.  S. G. Mourn, and  T. M. Goldhaft.   A Method for the Treat-
       ment of Animal Wastes  to  Control Ammonia and Other Odors.  Poultry
       Sci.  .48:1912,  1969.

83   Carlson  D. A., and  C.  P. Leiser.   Soil Beds  for  the Control of Sew-
       agl Odors.  Jour. Water Pol.  Control  Fed.   34:829-840, 1966.

84.  Carlson, D. A., and  R.  C. Gumerman.   Hydrogen Sulfide  and  Methyl  Mer-
       captans Removals with Soil  Columns.  Proc., 21st Industrial Waste
       Conference.   Purdue Univ. Engin.  Lafayette, Ind. 1966.

85.  Gumerman, R.  C.,  and D. A.  Carlson.  Chemical Aspects  of Odor  Removal
       in Some Soil  Systems.   In:   Animal Waste Management.  Cornell Univ.
       Conf.  on Agri.  Waste Management.   1969. p. 292-302.

86   Burnett  W.  E., and N. C.  Dondero.   The Control of Air Pollution (Odors)
       from Animal Wastes - Evaluation of Commercial Odor Control Products
       by an^rganoleptic Test.   Amer. Soc.  Agri. Engin. Paper 68-909, Decem-
       ber  1968.
                                        106

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87.  Willrich, T. L.  Manufacturers of Odor Control Chemicals for Use in
       Controlling Manure Odors.  Oregon State University.  Personal
       Communication.  1973.  2 p.

88.  Paine, Myron D.  Feedlot Odor.  Cooperative Extension Project GPE-7.
       Pub. GPE-7800.  Oklahoma State University.  1973.
                                        107

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                                   SECTION XVI
                                   APPENDICES
A.  Partial List of Proprietary Odor Control Chemicals                 110
      for Livestock Wastes
B.  Summary of Selected Court Cases Relative to Livestock              113
      Odors
                                        109

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                                  APPENDIX A

                   PARTIAL LIST OF PROPRIETARY ODOR CONTROL
                        CHEMICALS FOR LIVESTOCK WASTES
Manufacturer:
      Product:

      Type:

      Application  rate:



      Cost:
The Kalo Co.
2620 Ellington Rd.
Quincy, 111.   62301

Kalo K. 0.

Digestive deodorant, dry powder

3 lb/1,000,000 gal. Lagoon waste
0.5 Ib/ton manure
0.5 lb/10,000 sq ft floor area

$1.50/lb in 500 Ib  lots (3-70)
      Product:

      Type:

      Application rate;



      Cost:
Kalo 0. M.

Odor maskant, liquid concentrate

Applied by diluting 1 cup to 50
 gal. water, oil, or insecticide
 and spraying

$5/pint in 100 pint drum
Manufacturer:
      Product:

      Type:

      Application:
Manufacturer:
      Product:
Carus Chemical Co.
1500 Eighth St.
La Salle, 111.  61301

Cairox  (potassium permanganate)

Odor oxidant

1.  Spray a 1 percent solution on
    feedlots at 20 Ibs/acre
2.  Mix 5 Ibs of Cairox per 1000
    gal. liquid manure or spray a
    1 to 4 percent solution on
    tank at the same rate

Nilodor, Inc.
7740 Freedom Ave., N. W.
North Canton,  Ohio  44720

Nilodor Superconcentrate
                                      110

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      Type:

      Application:



      Cost:
Odor neutralizer

Concentrate volatilizes from an
 automatic dispenser.  One dis-
 penser every 10 ft of wall

$39.15 per qt in 4 qt lots (11/72)
      Product:

      Type:

      Application:
Nil-0-Sol

Nilodor plus detergent

Dilute 1 qt to 16-32 gal. as a
 cleaning solution
Manufacturer:



      Product:

      Type:


      Application:
Vineland Laboratories, Inc.
2285 E. Landis Ave.
Vineland, N.J. 08360

Methogen

Reacts with  ammonia,  fumes bacterio-
  cidal

1 Ib methogen per  100 Ibs manure
Manufacturer:
      Product:

      Type:

      Application;
       Product:

       Type:

       Application!
Wayne Animal  Health  Aids
Allied Mills, Inc.
 110 N.  Wacker Drive
 Chicago,  Illinois

Wayne D-ODOR #1

 Bacteria culture and enzymes

 Product is placed in water suspen-
  sion and applied to manure-covered
  surfaces where slurries  are  not the
  problem.  One ounce per  1000 sq ft
  weekly

  Wayne D-ODOR #2

  Bacteria culture and enzymes

  Water suspension is applied to ma-
   nure slurries or other liquids at
   the rate of 1 Ib per 10,000 gal.
   of material.
                                       Ill

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Manufacturer:
      Product:

      Type:

      Application;


      Cost:
Game Slatted Floor Co.
Box 3
Ransom, Illinois  60470

Solution "101"

Odor maskant

Dispensed into the air with a "Pig
 Puff" dispenser.

Pig Puffs:  $79.50 each
Solution "101": $7.95/gal»
                                      112

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                                APPENDIX B

       SUMMARY OF SELECTED COURT CASES RELATIVE TO LIVESTOCK ODORS

1966 Law Suit Against a Dairy Operation in Washington by Urban Neighbors.

The dairy was on land zoned for general uses with the operation of  a dairy
farm, permitted.  The land had been used as a dairy farm for many years  and
until three years earlier the herd was approximately 50 animals. The land
across the street to the south, zoned suburban agricultural, had been di-
vided into approximately five-acre tracts for homes.  The area was  typi-
cal of those found on the boundaries of a city.

Those who complained had not recently moved into the area, but most had
been there a number of years.  The principal complaint of the 18 plain-
tiffs was that because of the intensified operation of the dairy in the
last three years, odors arising from it had become a nuisance.  The herd
number had been increased to 200.

In an effort to solve the problem created by the waste of the dairy ani-
mals, the defendants constructed a large concrete holding tank.  All man-
ure was washed into the tank, reduced into a liquid state, and pumped into
a lagoon.  An earlier attempt to dispose of the liquid manure by spraying
it on the fields was abandoned because of the  odors created and because
drift from the spray fell on adjoining properties.  Those who complained
asserted that nauseous odors were emitted from the  lagoon.  The relief
sought was an injunction from maintaining the  open  lagoon.

The witnesses testified that the odors were intensely offensive, and that
when the weather was pleasant and conducive to outdoor activities  that it
was impossible to carry on  these activities because of these  odors  from
the lagoon.  Certain neighbors  called by  the defendants  testified  that they
were not greatly affected by odors since  their homes tended to  be  to the
side of prevailing wind patterns.
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The judge made some effort to examine the area and on  three occasions drove
on the streets.  On each occasion, the weather was cold  and the wind rather
brisk but unpleasant odors could be detected.   On one  occasion, by closer
inspection on foot in the neighborhood of the  lagoon,  some effort was made
to ascertain the presence of the offensive odors and some unpleasant odor
was noted which was different in quality, and  subjectively more offensive
than that generally associated with manure from cattle.  The  court was of
the opinion that if the odors emitted by the lagoon were of that intense
quality, those in the vicinity, indeed, would  be substantially affected
to an unbearable degree.

The problem arose because the increased number of cattle had  increased the
manure disposition problem far beyond that which existed when the dairy was
smaller.  The defendants have invested about $300,000  in their operation.
They have experimented with manure disposal.  They tried to dispose of it
by spraying it on the pasture and abandoned this method  at substantial cost
to themselves because of problems which spraying created.  They have not
attempted to use the lagoon system and have constructed  a lagoon into which
they pump about 100 cu m  (27,000 gal.) of liquid manure  every two days.

The thrust of the testimony of  the expert witnesses was  that  when they
visited, the lagoon seemed to be operating satisfactorily, and  they  detect-
ed no unusual odors.  However,  all seemed to agree, that lagoons are still
experimental and there is a great deal to be learned from them.

From the evidence, the judge found that  the operation of the  lagoon  con-
stituted a nuisance because of  the odors which  it  emitted from time  to
time.  Evidently, at times it had not  functioned  properly and there was
no reason to suppose that the condition would not recur.  He  continued
the case for four months, thereby withholding final judgment, to permit
the defendants to attempt to further  cope with  this problem by means  of
their own choosing, and suggested that they investigate the possibili-
ties of chemical additives; of  aeration by  the  discharge of air in pipes
in the body of the lagoon; of the introduction  of algae, if appropriate;
of enlargement of the lagoon system so that overload would not occur,  or

                                       114

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by such other means as their own investigation might suggest.

In court action four months later  (in April 1966) , a new attorney for the
dairy owner advised the abandonment of the lagoon and the installation of
a series of dug rectangular pits to receive the manure.  Black polyethyl-
ene film is used as a cover for the pits.  It was the contention of the
attorney, who has a background of  chemistry, that the pits would act as
anaerobic ones and that plastic covers would confine odors.

Patz versus Farmegg Products, Inc.  (1970).

This was a civil action for injunctive relief and to recover damages sus-
tained on account of a private nuisance.  The case was heard in the Dis-
trict Court, Webster County, Iowa,  during 1970.

Farmegg Products, Inc. purchased 1.63 ha (4.0 acres) of land in 1969 that
had a common boundary with a 100 ha (240 acre)  farm owned  and operated by
Mr. and Mrs. Patz.  FPI constructed two  buildings to grow  chickens to lay-
ing age on the four acre  tract.  These were  totally-enclosed, mechanically
ventilated buildings, each confining about 43,000 birds in cages suspended
over 25 on (10 in.) deep  pits.  Air exchange was  provided  by the ventila-
tion system to promote manure drying and coning so that the pits could re-
tain the manure produced  during  the 22 week  growing cycle.

At the beginning of each  growing cycle,  in January and in  July  1970, feed
and water spilled by the  baby chicks and spilled water from malfunctioning
waterers caused excessive moisture in  the manure and wasted feed retained
in the pits.  The combination of a high  ambient temperature required for
young chicks and a low air exchange rate to  maintain a high indoor  tem-
perature produced more concentrated odorous  gases in the  fan-exhausted air.

The Patz residence is located about 300  m (1,000 ft) west-northwest  from the
nearest  exhaust  fan.  The Patzes complained  about offensive odors  and  dust
exhausted  from  the buildings  and about manure spillage on the  public  road
in  front of  their home.
                                      115

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Evaluation of climatic data by defendant's counsel indicated that the
probability of odor detection in the Patz house yard would be about one
percent of the time.

Having heard the evidence, the Court found that odors coming from the
poultry buildings were offensive, that they were injurious and dangerous
to the health and comfort of the plaintiffs and thus interfered with the
plaintiffs' right to use and enjoy their residence, and that the invasion
of private rights was substantial and intentional; i.e., the decision to
use the existing system of manure handling without giving consideration
to the distance between the plaintiff's house and the poultry buildings.
For the purpose of determining the defendant's liability for damages, the
court found the conduct of the defendant to be unreasonable.

The court awarded $20,000 in permanent damages to the plaintiffs, and en-
joined the defendant from hauling manure upon the highway abutting the
plaintiffs' premises in such a manner that there was risk of spillage on
the highway.  The request for injunctive relief, except as indicated in
the preceding sentence, was denied.
Reference:  Patz versus Farmegg Products, Inc., Civil No. 43257 (Iowa Dist.
Ct., Webster Co., Dec. 2, 1970).

Hardin Co. versus Gifford Feed Lots, Inc. (1968).

This case, heard in the District Court, Hardin County, Iowa, during 1968,
concerned a public and private nuisance and noncompliance with zoning re-
gulations.

A land tract of about 12 ha (30 acres) was purchased in 1966, and a commer-
cial feedlot was constructed in an old gravel pit on this land.  Gravel had
been mined from the pit before 1930.  Use of the tract before 1965 was to
graze, feed and water a few horses and cattle.  The landowner constructed
two cattle pens and a shed in the gravel pit in 1965.  Gifford Feed Lots,
Inc.  expanded the facilities to 10 pens with a  combined capacity of about
1,200 head on about two ha (five acres)  in 1966.  The actual number kept
there ranged from 500 to 1,100 head.
                                      116

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Located in the old gravel pit, the feedlot area was poorly drained even
though the lot area was graded.  Shallow drainage ditches were constructed
to collect and convey drainage water  to a point from where the pooled
water was pumped to two lagoons  located at points of higher elevation.
Manure removed from the feedlot  was stockpiled near the rim of the gravel
pit for later field-spreading on adjacent cropland owned by others.

The feedlot was located 240 m  (800 ft) northwest of Gifford, an unincorpo-
rated village of about 100 people.  Gifford  residents  complained of offen-
sive odors, flies, and noise from bawling cattle and trucks.  They were
also concerned about possible  contamination  of  shallow wells in the vil-
lage.

Having heard  the testimony,  the  Court found  that the odors  and  flies  con-
stituted  a public  and private  nuisance that  could not  be  abated by measures
proposed  by the defendant.   The  court also  found that  Hardin County had
been zoned in 1965 and that  the  use  of lagoons  violated the zoning regula-
tions.  An injunction was decreed by the Court.  No  appeal  was  perfected.
Reference:  Hardin Co. versus  Gifford Feed  Lots,  Inc., Civil No.  62-160
 (Iowa  Dist. Ct., Hardin  Co.,  Dec.  23, 1968).

Trottnow  Versus Kullmer  (1968).

This  case was for damages and an injunction to abate alleged nuisance cre-
 ated by offensive odors  from a poultry house owned by Kullmer.   The  case
was heard in  the  district court of Iowa, Benton County, during 1968.   The
 poultry house in question was constructed in 1966 to accommodate 12,800
 hens.   A second,  similar house was constructed during March, 1967, thus,
 two similar buildings are involved.  Manure from the buildings was mech-
 anically scraped into one of two large manure holding pits.  Manure was
 scraped into the pits at weekly intervals or more frequently.  Water from
 the chicken waterers also was collected in  the manure storage pit and on
 occasion excess water was added to the manure to ease the scraping problem.
 The two manure pits had holding capacities  between 2-1/2 and 3-1/2 weeks
                                         117

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production.  Rather than have the pits filled, usual operating procedure
was to pump manure to a 5.7  cu m (1,500 gal.) mobile tank for transport to
cropland.  The defendants owned 31 ha (77 acres) on which this manure was
applied and some manure was  applied to neighbors' farmland.   The Trottnow
home is the only home within 0.8 km (1/2 mile) of the chicken houses.  The
Trottnow farmhouse is 58 m (190 ft) directly west of the closest chicken house.

The major complaint involved in the lawsuit was the odor emanating from the
chicken houses themselves.   Each building had ten 0.91 m (36 in.) exhaust
fans on the sides and the ends of the buildings.  All are thermostatically
controlled and operate continuously during warm weather.

The odors from the chicken house being blown to the Trottnow property
were particularly bothersome to tenants of the property.  They presented
testimony to the discomfort  which they suffered and indicated the odors
were having an adverse effect upon their health.  The tenant and his wife
eventually moved from the property and drove back and forth  to do the work.

The judge found the chicken  laying business was a substantial nuisance to
the owner and occupants of the Trottnow dwelling and specified certain
operational requirements that were to be met by the Kullmers.  These
included changes in the ventilation system, the manure handling system,
and manure application practices.  In addition, he specified they would
provide some method of preventing noxious odors which would unreasonably
pollute the air at the Trottnow farm buildings.  He maintained control
of the case and indicated that if additional problems were evident that
impartial observers should be obtained to make impartial observations as
to whether or not the odors  were objectionable.  Finally, the judge con-
cluded that Mrs. Trottnow had not at that point suffered compensable
damages but the tenants of her property had, in fact, suffered such.  A
sum of $1,365 was awarded, based upon their medical expenses and addition-
al living cost occasioned by the odors.
Reference:  Trottnow versus  Kullmer.  Civil No. 23482  (Iowa Dist. Ct.,
Benton Co., Aug 3, 1967).
                                      118

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Edwards versus Black (1968).

Mr. Black operated a commercial cattle feeding operation in a rural area
near Audabon, Iowa.  A group of 19 adjacent property owners charged that
the offensive odors, flies, and noise adversely affected their properties.
The jury found that no nuisance existed in this case and declared the con-
finement operation was a reasonable use of property in that locality.
The verdict indicated:
1)  the area in which the  feedlots were located was primarily an agricul-
    tural area;
2)  in spite of the numerous homes in the area, the feedlot was a reason-
    able use for that area;
3)  the odors had not polluted the air in and  around the plaintiff's pro-
    perties;
4)  the defendant had not  used his property  so as  to endanger the health
    of the plaintiffs;
5)  the operation and maintenance of  the  feedlot  did not constitute  a
    nuisance nor result in damages  to the plaintiffs;
6)  the operation of the  feedlot  did  not  constitute a.  continuing nuisance
The decision was reached  primarily on the basis of location.  Although
some  consideration was  given  to  distance  from the residences  as an element
of location,  the more important  consideration was the  character of the
surrounding  area.  Thus,  because  the  surrounding  area  was  predominantly
rural,  the  facility was  judged as being properly  located.
Reference:   Iowa Law Review.   1971.   "Ill blows  the wind that profits no-
body:"  Control  of  odors  from Iowa livestock confinement facilities.
57(2):451-505.   Edwards  versus Black.  Civil No.  15235-J28-170 (Iowa Dist.
 Ct.  Montgomery Co.,  November 5,  1968).

 Spencer Creek Pollution Control Association versus Lane Feedlots  (1970).

 This case was brought by an association of residents  and land owners
 against a cattle feedlot near Eugene, Oregon.  The complaints were of sur-
 face water pollution, groundwater pollution, odors, spread of animal dis-
 ease, unsightliness, and insect  and rodent infestation.  The plaintiffs

                                    119

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 sought monetary  damages  and  an  injunction to preclude cattle raising on
 the  property.

 The  feedlot had  capacity for approximately 1,000 head and expansions were
 proposed  to increase  this  to 1,500 head.  The operation included the
 feeding of beet  top silage during a portion of the year which contributed
 to the odor and  drainage problems.

 After  lengthy testimony  and  argument, the following orders were decreed:
 1)   Runoff of contaminated water to be kept from the nearby creek.
 2)   No more than 600  head of cattle were to be maintained on the property.
 3)   The amount of beet silage to be fed was limited.
 4)   Continued efforts to reduce odor escape were required.
 5)   Damages were awarded to  the various plaintiffs in amounts ranging
     from  $15 to  $1,850.
 Reference:  Spencer Creek Pollution Control Association versus Organic
 Fertilizer Co.   Case  No. 96125.  Circuit Court for the State of Oregon for
 Lane County.  August  25, 1970.

 Crandall  versus  Biergans (1972).

 In this case the plaintiffs  were seeking damage payment and an injunc-
 tion against W.  H. Biergans  who constructed a swine finishing barn on
his  property in  1965.  They  claimed that the swine operation constituted
 a private nuisance because obnoxious odors and toxic gases emanating from
 the  barn  were carried by the prevailing wind to the plaintiffs' property.
 Secondly, it was asserted that  the Michigan Environmental Protection Act
of 1970 had been violated because of air pollution.

The  swine building in question, 37 m (120 ft) long by 10 m (32 ft)  wide
had  a  partially  slatted  floor.  A manure storage tank 2.44 m (8.0 ft)
wide and  1.83 m  (6.0  ft)  deep ran the length of the building along the
 center line.  Manure, removed from the storage tank by a vacuum tank wagon,
was  spread on the defendant's cropland as a crop fertilizer.  Four 46 cm
 (18  in.)  exhaust fans were mounted along the east side of the confinement
barn to provide  ventilation.
                                      120

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In his opinion, the judge concluded  that  (a) the swine building was in an
area zoned agricultural and it was a farming area, and (b) the defendants
were conducting their operation in a husbandlike manner and were not neg-
ligent in their maintenance.

The court decided in favor of the defendants.  They were not maintaining
a nuisance.  On the basis of the evidence presented, the injury suffered
by the plaintiffs was not of such a  substantial nature as to warrant an
injunction against the swine operation or the relocation of the barn as
long as the defendant continued his  operation in a careful and husbandlike
manner and used such odor control products  or devices as are economically
feasible.

With respect to the Environmental Protection Act, the court determined
there were no  standards to judge  this  operation with respect to odors,
therefore, it  did not serve as a basis for  any  relief to  the plaintiffs.

Reference:  Crandall versus Biergans.   Michigan Circuit Court,  Clinton
County, File No. 844.  February  14,  1972.

Warden versus  Sinning  (1970).

This was  a civil action seeking  damages and injunctive  relief  because of
a private nuisance  caused by  offensive odors  from a  hog operation.   The
case was  heard by  a jury  in  the  District Court,  Marshall  County,  Iowa,
during  1970.

Mr.  and Mrs.  Leonard Warden,  the plaintiffs,  live on a grain  and livestock
 farm in a home that  is  located directly across the road from  the farmstead
 on the  Sinning property.   Mr.  Warden has lived on his  property 46 years.

 The Sinning  property is  also a grain and livestock farm.   A totally-enclosed,
mechanically-ventilated hog finishing building was built  in 1967 on the
 property  about 100 m (325 ft)  southwest  and across the road from the Wardens'
 home.  The building housed about 500 hogs on a partially-slotted floor,

                                        121

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with  a  liquid manure pit below the floor.  Manure pumped from the pit was
spread  on  the Sinning farm.

Having  heard the testimony, the jury failed to reach a verdict and was  dis-
missed.

A post-trial agreement between the two parties was reached on November
1970.   The Sinnings agreed to clean and fill the pit so that  it could
not be  used to store animal waste, and further agreed that no confinement
type of livestock raising would be conducted on their 65 ha (160 acre)
farm within 0.8 km (0.5 mile) of the Warden home so long as the Wardens
maintained a residence on their existing farm.

This agreement by the Sinnings is binding also on their heirs, successors
and assignors.  However, it does not prevent the S innings from using the
hog finishing building for purposes other than for the confinement of live-
stock or poultry or prevent them from the reasonable feeding  of hogs,
cattle, or other livestock on any part of their property in any ordinary
manner other than by confinement.

Reference:  Warden versus Sinning, Civil No. 30403 (Iowa Dist. Cr.,  Mar-
shall Co., May 25, 1970).

Winnebago Co. versus Fluegel (1970).

This case was heard by a judge in the Circuit Court, Winnebago County,  111.,
during  1969.  Plaintiffs included the County of Winnebago and eight inter-
vening plaintiffs who were owners of property in close proximity (usually
less than 1.6 km (1.0 mile) to the property owned by the defendant,  David
A. Fluegel.

A request for injunction was tried on two counts:   (a) that the use of  the
Fluegel property as a cattle feedlot was unlawful since it was contrary to
the zoning ordinance, and (b) that the cattle feedlot was both a public
and private nuisance because of odors, flies, other insects,  bacteria in

                                      122

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the air and nitrates in the groundwater that existed because of the feed-
lot operation.

The Fluegel property was located in an area that had been classified as
an "agricultural district" in 1942.  Fluegel purchased the 10 ha (24 acre)
property in 1969 and proceeded to construct a commercial feedlot.  The in-
tention was to construct a circular, funnel-shaped feedlot area on about
1.6 ha (4.0 acres).  The circular, concrete-surfaced area would be divided
into 12 pie-shaped pens, with all pen surfaces sloping toward the center
of the circle.  A shed was to be constructed in each pen.  The completed
feedlot was planned to confine about 2,800 head.

The circular feedlot area was graded from property boundary to property
boundary across the narrower width of the land tract.  A portion of the
area was concrete surfaced and sloped to drain to a sump in the center
of the circle.  The sump drained to an earthen pit through a corrugated
metal pipe.  Accumulated storm runoff was pumped from the pit and trucked
off the Fluegel property on at least one occasion; 1,400 cattle were placed
on the half-circle.  The manure disposal plan was to truck the solid ma-
nure to a Wisconsin-based composting operation.

The previous owner of the land tract was a cattle feeder.  A silo, hay shed,
cattle shed, and some cattle lots existed on the property when Fluegel
purchased it.  Testimony indicated the previous owner had finished as many
as 400 cattle at one time.

Having heard the testimony, the Court found that the defendant was operat-
ing a commercial cattle feedlot in an Agricultural Use District, which
feedlot was not a stock farm, a domestic animal-breeding operation, or a
use commonly classed as agricultural, but was  found to be a  stockyard or
a use substantially similar to that of a stockyard as defined under Indus-
trial Zoning.  Therefore,  the defendant was found in violation of  the zon-
ing ordinance.

The decree  further found  the  feedlot to be a public nuisance because of
the imminent  danger of  contaminating groundwater, of actual  pollution of
                                      123

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 surface water which escaped to nearby  properties, of  the existence of
 offensive odors with no effective means  to  control or abate the odors,
 and of substantially contributing to the fly population.  The feedlot
 was found a private nuisance also.  The  defendant was permanently enjoin-
 ed from using the premises as a cattle feedlot after March 1, 1970.  An
 appeal was not perfected.

 Reference:  Winnebago Co.  versus Fluegel, Chancery No. G-19425 (111.
 Cir. Ct., Winnebago Co., Jan.  31, 1970).

 Bower versus Hog Builders, Inc.  (1970).

 This was a civil action to recover damages  and seeking an injunction be-
 cause of a private nuisance.   The case was  heard by a jury in the District
 Court, Platte County, Missouri, during 1969.

 The plaintiffs were Mr.  and Mrs. Glenn Bower and Mr. and Mrs. Frank Bower.
 The Bower families live on adjacent farms of 23 and 22 ha (58 and 55 acres).
 They had lived on their farms  for 20 years  or longer.

 Hog Builders, Inc., the defendant, purchased a 56 ha  (139 acre) tract across
 the road north from the Glenn  Bower property in 1965  and constructed facili-
 ties for producing hog breeding stock.   Eleven hog buildings with a com-
 bined capacity of about 3,800  head were  constructed in 1965 and 1966. Open
 lots  for hog confinement  on the HBI property  covered about 12 ha (30 acres)

 All buildings were totally enclosed and  mechanically  ventilated with par-
 tially-slotted floors over 1.2 m (4.0  ft) deep liquid manure pits.  Pit con-
 tents  were emptied into anaerobic lagoons.  Eight lagoons, with a combined
 surface  area of about two  ha (five acres) were constructed between 1965
and  1969.   Lagoons were enlarged or added as needed to store from three to
four years'  manure production.

Plaintiffs'  testimony indicated that some lagoon overflow or release of
lagoon contents with  subsequent flow across the Frank and Glenn Bower

                                       124

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properties occurred on several  occasions.  On  one  occasion, a dislodged
plug on one lagoon drainpipe  permitted a  large volume  of  lagoon-stored
waste to flow across  the  Glenn  Bower property, through his stock watering
pond, and into a  creek.   Conservation Agent  Paul Tichnor  testified  that
he observed dead  fish in  both pond and creek on different occasions.

Runoff from about 4.9 ha  (12  acres)  of hog lot area drained across  the Glenn
Bower property and through the  larger of  Glenn Bower's two ponds  accord-
ing to the natural flow of water.   However,  eroded soil  and manure  from
the hog lot filled the road ditch  below the  lot so that  the road  was  over-
topped by runoff  water.   This permitted hog  lot drainage to flow  into
the smaller, second pond  on the Glenn Bower  property and near the vicinity
of his shallow, house well.

The Glenn Bower home  was  located about 250 m  (800  ft)  from the closest an-
aerobic lagoon and a  somewhat lesser distance from the hog lot.   The Frank
Bower residence was located a greater distance from these odor sources.
Both Bower families testified as to how obnoxious  odors from the HBI pro-
perty affected the uses  and values of their properties.

According  to wind direction frequencies, odor would be transported from
 the HBI property  toward  the Bower properties  from 16  to 31 percent of the
 time, varying  from month to month based on an evaluation of Kansas City
weather  data made by  an  expert witness for the plaintiffs.

Having heard  the evidence  submitted  during the proceedings, the Court
 awarded  $46,200  in actual  damages and  $90,000 in  punitive damages  to the
 Bower families.   The greater amount  went to the Glenn Bower family who
 suffered the greater damage.    The presiding judge had excluded an  injunc-
 tion as  a possible choice.

 The decision was appealed.   After reviewing the case, the Supreme  Court
 of Missouri upheld the District Court's  decision  in December 1970.

 Reference:  Bower versus Hog Builders, Inc. 461 S.  W. 2d 784  (Mo.  1970).

                                        125
  ftU-S. GOVERNMENT PRINTING OFFICE: 1974 546-319/404  1-3

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
 . REPORT NO.
 EPA-660/2-7^-023
                                                           3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
   ODORS FROM CONFINED LIVESTOCK PRODUCTION
             5. REPORT DATE
                 April 197*1
                                                           6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)

        J. Ronald Miner
                                                           8. PERFORMING ORGANIZATION REPORT NO.
fl. PERFORMING ORG \NIZATION NAME AND ADDRESS
        Agricultural  Engineering Department
        Oregon State  University

        Corvallis,  Oregon 97331
             10. PROGRAM ELEMENT NO.

                 1BB039
             11. CONTRACT/GRANT NO.

                 R802009-01
12. SPONSORING AGENCY NAME AND ADDRESS
        U. S. Environmental Protection Agency
        Washington,  D.C.  20460
             13. TYPE OF REPORT AND PERIOD COVERED
             14. SPONSORING AGENCY CODE
16. SUPPLEMENTARY NOTES
16. ABSTRACT
 Current livestock  production techniques result  in  the generation of odors which have
 become a source of conflict between livestock producers  and society.  The odorous
 gases responsible  for  the nuisance are principally low molecular weight compounds  re-
 leased during anaerobic decomposition of manure.   Manure management systems which  con-
 trol or modify this  decomposition offer the greatest  potential for odor control.

 Research to identify the chemical compounds present in odorous air from animal waste
 degradation has yielded about 45 compounds to date.   The amines, mercaptans, organic
 acids and heterocyclic nitrogen compounds are generally  regarded as being of greatest
 importance.  Among the techniques for odor control are:   (a) site selection away from
 populated areas and  where adequate drainage exists, (b)  maintain the animal areas  as
 dry as possible and  prevent the animals from becoming manure covered, (c) select man-
 ure handling systems which utilize aerobic environments  for manure storage, (d) main-
 tain an orderly operation free of accumulated manure  and runoff water, (e) practice
 prompt disposal of dead animals and (f) use odor control chemicals when short term
 odor control is necessary, such as when manure  storage tank content! mu«t be field
 spread.
                           (Miner - Oregon State  University)
17.
                               KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
 *0dor, livestock,  *Legal aspects, Cattle,
  Hogs, Poultry, Hydrogen  aulfide, Ammonia
 *01faction, *ammonia  de-
  sorption, *Livestock
  manure, *Manure, Odor
  control
   05A

   05C

   05D
18. DISTRIBUTION STATEMENT

  Release Unlimited
19. SECURITY CLASS (This Report J
21. NO. OF PAGES
    135
20. SECURITY CLASS (This page)
                           22. PRICE
EPA Form 2220-1 (»-73)

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