SEPA
United States
Environnn"
Age1
Industrial Environmental Research F
Laboratory
Cincinnati OH 45268
Research and Development
Control of Odors
From Anaerobic
Lagoons Treating
Food Processing
Wastewaters
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-151
July 1978
CONTROL OF ODORS FROM ANAEROBIC LAGOONS
TREATING FOOD PROCESSING WASTEWATERS
by
J. Ronald Miner
Agricultural Engineering Department
Oregon State University
Corvallis, Oregon 97331
Contract No. CC691935-J
Project Officer
Jack L. Witherow
Food and Wood Products Branch
Industrial Environmental Research Laboratory
Corvallis, Oregon 97330
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Re-
search Laboratory - Cincinnati, U. S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U. S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or rec-
ommendation for use.
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution con-
trol methods be used. The Industrial Envuronmental Research Laboratory-
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet these ends both efficiently and economically.
This report reviews the physical chemistry involved in odor release
from liquid surfaces, mechanisms of odor perception, and techniques currently
employed for odor measurement. These concepts and data are applied to anaer-
obic lagoons as presently being used to produce a low cost, energy-efficient
device for treatment of organic wastes. Field experiences are related in
which meat packing plant lagoons presented a problem due to odor complaints.
Finally, the technology is identified which must be developed in order
for anaerobic lagoons to receive societal sanction. A research plan is pre-
sented to evaluate one proposed solution to the technology need. For further
information on the subject, contact H. Kirk Willard, Chief, Food and Wood
Products Branch.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
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ABSTRACT
Anaerobic lagoons are used for the treatment of meat packing wastes
in most areas of the country. They are a relatively low cost means of achiev-
ing BOD reduction. Although lagoon effluent is not suitable for stream dis-
charge, it is amenable to further treatment or to land application.
One of the most serious limitations of anaerobic lagoons in this appli-
cation is odor production. Odor complaints have been widespread but have
been most frequent in areas of high sulfate waters and during start-up.
There has been little specific research effort devoted to anaerobic lagoon
odor control.
This report assembles existing information relative to odor control
associated with anaerobic lagoons used in the meat packing industry and ident-
ifies opportunities for productive research. It provides a basis for
approaching the overall problem in a comprehensive fashion. This report
identifies six research techniques which could make significant contributions
toward solving the odor problems.
This report was submitted in fulfillment of Contract No. CC691935-J by
the Agricultural Research Foundation of Oregon State University under the
sponsorship of the U.S. Environmental Protection Agency. It covers the
period July 1, 1976 to December 31, 1976, and work was completed as of Dec-
ember 31, 1976.
IV
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CONTENTS
Foreword iii
Abstract iv
Figures and Tables vi
Acknowledgments vii
1. Introduction 1
2. Doctrine of Nuisance 3
3. Theory of Odor Perception 5
4 . Quantitative Measurement of Odors 15
5. Release of Ammonia and Hydrogen
Sulfide from Liquid Surfaces 20
6. Anaerobic Lagoon Design and
Operation 29
7. Field Experience 31
8. Problem Analysis 36
9. Research Needs 39
References 40
Appendix 43
v
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FIGURES
Number Page
1 Scentome ter 17
2 Effect of solution pH on fraction
dissolved reactant dissociated (ionized) 26
TABLES
Number Page
1 The human senses, examples of parameters
measured and alternate information sources 6
2 Basic odor quality classifications as
described by five authors 11
3 Dilution to threshold values with various ports
open on a scentometer when an odor is barely
detectable 18
4 Results of laboratory anaerobic lagoon
studies to predict sulfide concentrations 27
5 Analysis of a gas sample collected in a bell
jar over an anaerobic meat packing waste
lagoon in New Zealand 32
6 Composition of gases inside the Controliner at
University of Illinois swine farm 35
VI
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ACKNOWLEDGMENT
The preparation of this report was supported in part by Contract
CC691935-J, U.S. Environmental Protection Agency. The counsel and coopera-
tion of Jack L. Witherow, Project Officer, Food and Wood Products Branch,
Industrial Environmental Research Laboratory-Ci, Corvallis, Oregon, is
gratefully acknowledged.
Vll
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SECTION 1
INTRODUCTION
Anaerobic lagoons have been identified as low-cost means of
treating meat plant wastes. They have achieved widespread appli-
cation throughout this country and much of the world. The great-
est application has been to small- and medium-sized packers; how-
ever, anaerobic lagoons have been utilized for several larger
packing plants.
Anaerobic lagoons are basically engineering earthen basins which
detain waste while it undergoes anaerobic bacterial decomposition.
The rate of decomposition is a function of organic matter concen-
tration and temperature. Since meat packing wastes typically in-
clude significant proportions of hot water, they respond well to
lagoon treatment.
One of the most frequent problems mentioned relative to anaerobic
lagoons is odor. Being an anaerobic biological process, the end
products are highly reduced components. Typical constituents are
ammonia, methane, hydrogen sulfide, and carbon dioxide. Other
intermediates involved in the decomposition of many by-products
include amines, mercaptans, alcohols, ketones, and other more
complex organic compounds. Therefore, anaerobic lagoon contents
are a solution of input, intermediate breakdown products, and end
products of bacterial decomposition.
In order for an odor problem from an anaerobic lagoon to arise,
a series of events must occur. The odorous compound must be
discharged to the lagoon or be formed within the lagoon by an-
aerobic biochemical processes. The odorous compound must vola-
tilize and escape from the lagoon surface. The volatile odorous
gas must be transported from the lagoon surface to the proximity
of people. And finally, there must be people to serve as re-
ceptors who are offended by the smell they perceive.
The chain of events necessary for an odor problem to arise also
provides a key to the control of odors. Remedial measures which
halt or modify any one or more of the events leading to odor pro-
blems can be expected to decrease or change perceived odor in-
tensities.
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The purpose of this report was to assemble existing information
concerning anaerobic meat packing plant waste treatment lagoon
odors in a single location and to draw from this information
guidance in effective odor control technology development.
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SECTION 2
DOCTRINE OF NUISANCE
Ownership of land includes the right to impregnate the air with
odors, dust and smoke, pollute the water, and make noise, pro-
vided these actions do not substantially interfere with the com-
fort of others or hamper 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 and is applied to a
series of wrongs which may arise from unreasonable, unwarranted
or unlawful use of property to produce annoyance, inconvenience,
discomfort or hurt that the law will presume to be a damage. What
constitutes a nuisance in a particular case must be decided based
upon the facts and circumstances of that instance.
Nuisance has been classified as either public or private. A
nuisance is said to be public when the public at large or some
considerable portion 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 is
grounds for a civil proceedings only.
The fact that a business is carried on carefully and in accord-
ance with the ordinary methods employed in that business does not
relieve the owner or person responsible for liability to a. neigh-
bor if that business is unreasonable and constitutes a nuisance.
Paulson (1967) 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 discomfort that must be produced to constitute
a nuisance must be determined upon the basis of being reasonable
or unreasonable.
For an odor to be considered a nuisance, the stench must be of-
fensive to the senses and materially interfere with the comfortable
enjoyment of property within the area (Paulson, 1967). It is not
necessary that the odor be harmful or unwholesome. It is suffi-
cient if it is offensive or produces such consequences, inconven-
ience or discomfort as to impair the comfortable enjoyment of pro-
perty by persons of ordinary sensibility.
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A person who suffers damages or feels that he suffers damages be-
cause of the odor of a livestock operation has two courses of ac-
tion open to him: a suit for damages, or a suit to enjoin or abate
the nuisance—and he may pursue either or both. The remedies of
injunction or abatement are generally considered harsh by the
courts; normally, only that part of the operation which amounts
to a nuisance will be abated or enjoined. When the nuisance re-
sults solely because of the method of operation or manner in which
business is conducted, the decree will be formed only to prevent
that particular method or manner rather than prohibiting completely
the use of the property by the person creating the nuisance.
It is an essential element for injunctive relief that annoyance
or injury be continuous or recurrent. The use of premises which
create a nuisance may be enjoined, however, if it reasonably ap-
pears that such annoyances or injury will be recurrent.
To be liable for actual damages one need only create or commit a
nuisance. The injured party is normally allowed to indicate the
best or most advantageous use of his property; this is then used
as a basis for determining the amount which would be adequate and
fair compensation (Paulson, 1967) . Punitive damages are allowed
only when it can be shown that one has created and persistently
maintained a nuisance with reckless disregard for the rights of
others, or when one has reason to believe that his act may injure
another and does it in defiance of 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 penalty.
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SECTION 3
THEORY OF ODOR PERCEPTION
Each of the five senses is used to bring us information about our
environment. 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 understanding of its status and changes. The
response to these senses is essentially a personal reaction.
Whether a sound is pleasant, a feeling satisfying, a taste enjoy-
able, a scene beautiful, or a smell desirable is fundamentally
an individualized response based upon cultural background and
momentary disposition of the individual.
The senses of touch, taste, hearing and sight all measure environ-
mental parameters also measurable by other techniques as shown
in Table 1. The sense of smell is unique in that no mechanical
or chemical alternative device exists for measuring odor. Thus,
odor is largely a subjective phenomenon for which no quantitative
standard of comparison exists.
The human nose is the basic detector in odor analysis. It may
be supplemented in some cases by other instruments, but there is
no replacement for it even though the complexities of its function-
ing are not thoroughly understood (Earth, 1970). Moulton (1965)
stated that the final approach in odor and flavor identification
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 preceded by an understanding
of the way the nose functions to distinguish one odor from thousands
of others.
Inspired air typically travels into the nostrils, through the tur-
binate area and down the throat to the lungs. Normal breathing
causes 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 obvious from a concerted sniff than from the normal breathing
rate.
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TABLE 1. THE HUMAN SENSES, EXAMPLES OF PARAMETERS MEASURED
AND ALTERNATE INFORMATION SOURCES
Sense
Sight
Sound
Taste
Touch
Smell
Parameter
measured
Color,
intensity
Pitch,
intensity
Saltiness,
sour
Temperature ,
hardness
Odor
Alternate
device
Colorimeter,
light meter
Tuning fork,
microphones
Chemical
titration pH
Thermometer
None
Unit of
measurement
Wave length,
lumens
Frequency,
decibels
mg/1, pH unit
Degree
None
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The olfactory nerve cells are located in the olfactory cleft area.
The total olfactory reception area in the adult human is about
two inches square. Olfactory cells are long and narrow, and are
oriented perpendicular to the surface of the receptor area; cells
are pigmented yellow or yellow-brown. There are different kinds
of odor receptor cells—cells that respond to different odor stim-
uli. On the exposed end of the nerve cells are five to eight ol-
factory hairs extending into or through the mucous layer which
coats the surface of the mucous membrane.
It is believed that olfactory hairs are the means of reception
of the "signal" of the odorous molecule. A chain of events fol-
lows which instantaneously gives odor perception. The hairs are
kept moist by the mucous layer. An excess of mucus, as in the case
of a head cold, can incapacitate the hairs and, thus, the sense
of smell.
Moncrieff (1966) 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 air
of a sniff is beneficial but not essential.
(c) The odorous molecules are adsorbed on appropriate sites
on the olfactory 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 sen-
sation 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 com-
pound or to formulate a compound with a required odor. Recent
findings have shown that odor is closely associated with molecular
configuration, but this, according to Moncrieff (1967), is only
half the story of odor perception. The other half consists of the
receptor system and 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 sensa-
tion vanishes.
(d) Water, though having the characteristics of other odor-
ants, has no odor.
7
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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 per-
ceive 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 in the method
by which the "message" of the odorant is transmitted to the ol-
factory nerve. Primary theories have proposed (a) chemical
reaction, (b) physical adsorption, 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 (Moncrieff, 1967). An odor-
ant 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. After a short time, the air passing through the head con-
tained a concentration of odorant equal to that entering. The odor-
ant supply was cut off and the airstream continued to circulate
through the nasal cavity until no odorant was detected in the exit
air. After a period of time, up to several hours, the air flow was
again started. No odorant was added. The discharged air again con-
tained the odorant in its original form. No chemical action had
taken place. The process of adsorption is essential in odor per-
ception.
The stereochemical theory of Amoore (1963) 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 proposed to serve the seven primary odors—
ethereal, camphoraceous, musky, floral, pepperminty, pungent, and
putrid. Other odors resulted from combinations of primary odors.
Amoore has more recently altered his theory to account for a two-
dimensional rather than three-dimensional fit. Molecular silhou-
ette of cross-sectional area is the important steric characteris-
tic of the odorant (Amoore et al., 1967). Odor perception is in-
itiated by an energy change brought about by adsorption of the
odorant molecule on the olfactory nerve.
Residence time of the odorant substance on the nerve is on the
order of 10"° seconds. The time required for the puncture to heal
8
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is longer—on the order of 10~4 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.
These theories are the basis for most of the research related to
olfactory perception in recent years. Two points of agreement
exist in these theories: (a) the process is initiated with the ad-
sorption 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 translated to the olfactory
nerve. It is feasible that all 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 substance 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. ASTM Special Technical
Publication No. 434, "Manual on Sensory Testing Methods" (ASTM,
1968) effectively describes the ground rules for conducting odor
strength and quality tests. The manual states requirements for
physical facilities, test subjects, and samples to be tested.
Kinds of tests that may be applied are discussed along with pro-
cedures for analysis of the data. The manual does not, however,
describe the detailed procedure by which individual tests must
be conducted. Such details are dictated by the kind of material
and characteristic of odorant being judged.
The most common method of measuring odor intensity is by dilution
to extinction. An odorant is diluted with an odor-free medium
until its odor can no longer be detected. The greatest dilution
at which the odorant is just barely detectable is termed its thresh-
old value. Baker (1964) compared four common procedures for deter-
mining threshold value of an odorant in odor-free water dilution:
(a) Standard Method, STD: five flasks containing serial dilu-
tions plus one "catch trial" blank;
(b) Consistent Series, CS: five flasks containing serial dilu-
tions plus two blanks;
(c) Triangle Test, TT: three flasks at each dilution level,
two which are blank; and
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(d) Short Parallel, SP: two flasks at each dilution level,
one of which is blank.
Tests were run using two odorants, n-butanol and m-cresol. Re-
sults showed that the tests, in order of decreasing sensitivity,
were TT, CS, SP and STD. However, Baker points out that no test
is obviously superior when performed under controlled conditions
with trained personnel.
Odor intensities are stated in terms of odor intensity index,
Oil, or threshold odor number, TON. The two values are related,
according to the equation
2OII = TON
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 Oil to TON. Certainly an Oil value of 15 is less cumber-
some 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 pro-
cedures and conditions of the test are standardized. ASTM (1968)
states that the minimum number of observers for any test is five,
since any fewer places too much dependence on the response of any
one individual. Subjects must pass a preliminary screening to
assure that they are capable of making a normal response to the
stimuli to be presented.
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 could result from a light, well-ventilated house with
little more than the smell of must or feed to a highly populated
house with poor ventilation, high humidity, and concentrated
ammonia. One's interpretation might 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. Five of these
lists are presented in Table 2. Classes of similar qualities are
placed on the same line.
Qualitative odor testing is widely used in the food and perfume
industries; however, use of qualitative odor testing in waste
treatment research is limited. The test is often made by com-
paring an unknown with a known odorant of similar or dissimilar
10
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TABLE 2. BASIC ODOR QUALITY CLASSIFICATIONS
AS DESCRIBED BY FIVE AUTHORS (MONCRIEFF, 1966)
Zwaardemaker
1895
Henning Crocker and Amoore
191.6 Henderson, 1927 1952
Davies
1965
Ambrosial Musky Musky
Balsamic or Flowery, Fragrant Floral Floral,
fragrant resinous cedary
Ethereal Fruity Ethereal Ethereal,
fruity
alcoholic
Aromatic Spicy Camphoraceous Camphora-
ceous,
aromatic
Minty Pepper-
minty
Empyreumatic Burnt Burnt Almond
Alliaceous Foul
Caprylic Caprylic
Repulsive
Nauseating, Putrid
foetid
Acid Pungent
11
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quality in paired comparisons. The observer then judges the
degree of similarity.
Odor quality testing lacks the desired objectivity of odor thresh-
old determinations. Quality tests require observer judgments rel-
ative to a known odorant and subjectivity is unavoidable.
LIMITATIONS OF ODOR TESTING
The limitations of odor testing arise from the existence of odor
phenomena and the preferences (or subjectivity) of observers.
The sources of these limitations will be discussed individually.
It should be apparent how each limitation can enter into the inter-
pretation of odor test results.
Adaptation
Adaptation is the adjustment of the observer to an odor stimulus.
The level of sensation diminishes with time even though the stimulus
is applied at a steady rate. Observers who enter the vicinity of
lagoons soon lose the ability to make unbiased odor judgments about
odorants similar to those of the immediate environment. Rate
of adaptation varies with strength of the stimulus. Moncrieff
(1966) demonstrated adaptation as follows: 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 thresh-
old concentration. The effect of a dissimilar odor was not so
great—after smelling pure acetone, n-butanol could be recognized
at 0.06 percent, or 12 times threshold concentration.
Fatigue
Fatigue is the result of adaptation. Exposure to a strong odorant
may completely exhaust the capability to sense odor. Fatigue de-
velops gradually, with an exposure of two to three minutes required
for total exhaustion. Recovery after removal of the odorant re-
quires 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 fatigue for all odors.
Odorant Concentration
Changes in odor quality sometimes occur due to dilution. For ex-
ample, concentrated furfuryl mercaptan has a nauseating odor but
is reminiscent of the aroma of coffee when greatly diluted.
Moncrieff (1967) reported the concept of limiting intensity, which
states that the human nose cannot distinguish between odorant con-
centrations greater than saturation level. The reasoning behind
this concept (which heavily supports the adsorption theory of od-
or) is that receptor sites become filled with odorous molecules
and an increase in the number of molecules inspired causes no in-
crease in sensation.
12
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Mixtures
Rosen et al. (1962) listed four possible reactions for mixtures
of two individually odorous components. In these equations, R,
is the odor stimulus of component A, RB is the odor stimulus or
component B, and RA+B is the odor stimulus from the combination of
components A and B.
(a) Independence RA+B = RA or RR
(b) Antagonism or RA+R < R or R
counteraction B A B
(c) Additions R, ._ = R, + R
(d) Synergism Ra > R + R
A
Moncrieff (1967) described counteraction (the mutual discrimina-
tion) of two odors to the extent that they are odorless in combin-
ation. Using low concentrations of the odorants they tended to be
additive, but with certain combinations of high concentration,
the effect was no odor. Guadnagni et al. (1963) found that com-
bination 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 unpredict-
able. In addition, the type of reaction can vary according to the
concentration of the components.
Anosmia and Parosmia
Anosmia (odor-blindness) is a condition which affects about 10 per-
cent of the population. Partial anosmia — anosmia for a group of
similar odors — is more common than complete anosmia. Partial anos-
mia is much more likely to exist without the knowledge of the af-
flicted person.
Parosmia (perversion of odor) is a second type of olfactory di-
sease: the parosmatic senses a different odor than the one put
before him. The perverted odor is often an unpleasant one. But
the condition is likely to be temporary.
Pungence
"Pungent" has been included as a basic odor type by some authors.
This classification is associated with strong acidic and basic
smells. Pungence may not be a true olfactory nerve response, but
a sensation of pain caused by irritation of the trigeminal nerves
in the nasal* cavity.
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SUPPLEMENTARY INSTRUMENTS
The gas-liquid chromatograph, GLC, has been the most important in-
strument in supplementing the capabilities of the human nose in
odor research. While the nose can best determine 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 sensi-
tivity of the GLC and, therefore, greater capacity to identify
the trace quantities of odorants in complex materials.
Odormeters of various forms have been developed to assist in test
work. The meters are of the general form that can make the neces-
sary dilutions of odorant with odor-free air prior to inspiration.
The meters have been given such names as "osmoscope," "odormeter"
and "osmometer."
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 continues to be the lack of understanding of the
odor perception process of the human nose. Even so, several re-
searchers have made efforts to duplicate the human nose.
14
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SECTION 4
QUANTITATIVE MEASUREMENT OF ODORS
The technological difficulties of quantitative odor measurement
are formidable. Odor is essentially a subjective response to the
mixture of chemical compounds present in air. This response is
a function not only of the chemical make-up of the air but also
of the psychological disposition of the observer as well. Eval-
uation of an odor is thus a complex physiological and psychological
process and it is little wonder that techniques for quantitative
measurement of odors have been fraught with difficulty. Two sep-
arate 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 indistinguish-
able from odor-free air by the human nose. That concentration
barely distinguishable from odor-free air is termed the thresh-
old 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 threshold concentration.
Similar to the air dilution technique is a liquid dilution method.
In this technique, a sample of odorous material is mixed with odor-
free water. Generally, the diluted sample along with some odor-
free samples is offered to a panel of observers. The general
technique is to make up a series of five bottles for the panel,
two containing a dilution of odorous material, the other three
containing odor-free water. Panel members are asked to mark on
their score sheets those bottles which contain the odorous mate-
rial. By making a series of dilutions and offering them to the
odor panel for evaluation, minimum detectable concentrations of
the material can be determined. By making liquid dilutions suc-
cessively greater by a factor of two, resulting data can be used
to determine an odor intensity index (Oil). In other words, if
threshold odor were determined to be diluted 15 parts odor-free
water to one part odorous solution, the odor intensity index would
be 4. A second means of expressing this information would be a
threshold odor number (TON), which is equal to two raised to the
odor intensity power.
15
-------
SCENTOMBTER
Field measurements of odor intensity are difficult because of the
lack of an overall acceptable measuring device and the inability
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 (1/16-, 1/8-, 1/4- and 1/2-inch in diameter).
The odorous inlets are directly connected to a mixing chamber and
the nasal outlets (see Figure 1).
In field operations, the observer takes the scentometer where
odor intensity is to be measured. He places the device to his
nostrils, covering 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 is that any air entering his nostrils
under these conditions will have passed through the activated char-
coal bed and be odor-free. Once the observer's 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 suc-
cessively larger diameters beginning with the 1/16-inch port. He
continues in this manner until an odor is first detected coming
through the device. The design is such that odorous air is mixed
with filtered air in definite proportions so that recording the
port or ports opened at the time an odor was first detected pro-
vides a measure of the dilutions required to reach the odor thresh-
old. Table 3 provides a correlation between the ports which are
open and the calculated dilution entering the nostrils of the
observer. With a combination 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 inability of the
observer to detect small differences in odor intensity.
In discussing the scentometer, Huey et al. (1960) stated that their
experience had shown that odors about seven dilutions to threshold
would probably cause complaints while those measuring 31 dilutions
to threshold could be described as a serious nuisance if they per-
sisted for a considerable length of time. The scentometer was
described in a paper by Rowe (1963), in which he indicated that
it required about ten times the perceptible odor threshold to give
a definite sensation of odor and another tenfold increase to be
considered a strong odor.
The scentometer has received rather widespread application in ani-
mal waste odor evaluation. In spite of its application, however,
there are several basic limitations to this approach. The sensi-
tivity of the observer is highly Important in determining the
values achieved with the instrument. Although sniffing through
the scentometer with odorous air ports closed is designed to re-
store normal sensitivity, complete restoration of sense of smell
16
-------
ODOROUS AIR
INLET PORTS
J_" J_"_L'_LM
2 4 8 16
SNIFFING
PORTS
SCREEN ON BOTH
SIDE OF CHARCOAL
FILTER
Figure 1. Scentometer
-------
TABLE 3. DILUTION TO THRESHOLD VALUES
WITH VARIOUS PORTS OPEN ON A SCENTOMETER
WHEN AN ODOR IS BARELY DETECTABLE
Dilutions
to threshold
1.47
1.49
1.55
1.88
2.0
5.55
5.75
6.75
7.0
27.0
31.0
170.0
1/2 in.
0
0
0
X
0
X
X
0
X
X
X
X
Odorous
1/4 in.
0
0
0
0
X
0
0
X
0
X
X
X
air inlets1
1/8 in.
0
0
X
X
X
0
0
0
X
0
0
X
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
18
-------
may not occur rapidly enough to obtain meaningful results. The
charcoal bed can become saturated and not give complete odor removal
from air breathed when all ports are closed. Since there is no
indicator to show if the carbon is saturated, misleading results
may be obtained under these conditions. Intermittent odors common
in animal waste, particularly when observations are made some dis-
tance from the odorous source, present additional difficulties and
require use of the scentometer over a considerable period to obtain
representative data. In spite of these limitations, however, the
scentometer is a useful device, and is being used by some regulatory
agencies.
ODOR QUALITY
In contrast to odor strength, which can be quantitatively evalu-
ated, there is no straightforward technique to quantify odor qual-
ity. Most frequently, odor quality is described by comparison to
a common odorant or sensation with which the reader or listener
is familiar. For example, White et al. (1971) used the following
terms to describe the odorous components of dairy waste: foul,
sweetish, acetate, nutlike, pungent, and musty. In describing the
odor of various fractions of poultry manure odor, Burnett (1969)
used the following words: rotten egg, rotten cabbage, onion-like,
putrid, butter-like, and garlic.
An alternative method to evaluate odor quality was used by Sobel
(1971). He asked a panel of odor evaluators to select a number from
one to ten, indicating the degree of offensiveness of the samples.
A nonoffensive odor was marked as 0, a very strong offensive odor
was ranked as 10, a definite offensive odor was 6 and a faint of-
fensive odor was 4. 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, rotten egg,
petroleum, earth, yeast, ammonia, grain, feed, sour, fermented,
and cabbage. Using this approach, he was successful in differ-
entiating the offensiveness of an odor and the odor strength.
19
-------
SECTION 5
RELEASE OF AMMONIA AND HYDROGEN SULFIDE
FROM LIQUID SURFACES
Wastewaters of both human and industrial origin contain sulfurous
and nitrogenous compounds which have been implicated as contribut-
ing to odor production. Under anaerobic conditions/ these com-
pounds are typically converted to their most reduced states, hy-
drogen sulfide and ammonia. The evolution of these compounds has
been investigated from a physical chemistry perspective in work
summarized in a paper prepared by C. N. Click and J. C. Reed,
entitled "Atmospheric Release of Hydrogen Sulfide and Ammonia from
Wet Sludges and Wastewaters." Their material has been utilized in
this discussion where it is pertinent to the release of odorous
materials from anaerobic meat packing plant lagoons.
HYDROGEN SULFIDE IN WASTEWATER
The evolution of hydrogen sulfide (H~S) from sewage has been docu-
mented frequently for sewers and sewage works. Gravity sewers and
force mains may produce soluble sulfide buildup to the point of odor
nuisance, sewer corrosion and toxicity. Gravity sewers are less
subject to sulfide production than force mains since more oxygen
is available in gravity sewers and oxygen must be virtually absent
from sulfide accumulation. Oxygen will eventually cause previously
formed sulfides to be converted to soluble non-volatile sulfates.
Iron and other heavy metals form insoluble suspensions of sulfides
which are not normally available for reaction of H-S.
In most wastewaters, sulfides are usually present in both organic
and inorganic forms. The organic "sulfides" are not measured by
the usual wastewater tests, but they may contribute to nuisance
conditions either by being odorants (such as mercaptans, thio-
ethers, and disulfides), or by contributing soluble "inorganic"
sulfides via biological degradation. Inorganic sulfides may
be measured by the standard wastewater tests but not all of the in-
organic sulfides may be available for H_S formation because as noted
above, some heavy metals form insoluble sulfides.
The threshold of taste/odor detection of H~S is reported to be
between 1.0 x 10~ and 1.0 x 10T mg/1 in water (Pomeroy and Cruse,
1969) and to be about 4.7 x 10~ ppm in air (Leonardos et al., 1969)
where ppm is by volume. The threshold limiting value (TLV) for
H_S in air is 10 ppm, but various studies (WPCF, 1969) have reported
20
-------
that 100 to 300 for one hour is the maximum tolerable short-time
exposure or even that 300 ppm can cause death in a short time. The
low concentrations of taste/odor detection practically guarantee
that odor nuisances exist before toxicity problems can occur and
sometimes before noticeable corrosion results. Unfortunately/ the
higher (greater than 10 ppm) concentrations render the olfactory
sense ineffective very quickly, so workers are not continuously re-
minded of the danger.
AMMONIA IN WASTEWATER
The evolution of ammonia (NH,.) from wastes is possible. Meat pack-
ing wastes contain nitrogen in several forms. Most is derived
from the breakdown of the organic materials, urea and protein.
The thresholds of odor detection and recognition of ammonia
have been reported (Stahl, 1973) to be between about 0.04 and 47
ppm. It is interesting that although the 1972 TLV for ammonia was
given as 50 ppm, proposed changes would reduce the TLV to 25 ppm.
HYDROGEN SULFIDE EVOLUTION AND pH
Substances that react in aqueous solution to accept or donate
electrons (and consequently donate or accept protons) dissolve to
a degree dependent upon solution pH and their dissociation con-
stant (K). For an acid the equilibrium dissociation constant,
K, is defined by the dissociation equation, which for H2S is:
H2S JHS~ + H+ (1)
The subsequent dissociation of the bisulfide ion (HS ) into a
second proton and sulfide ion with a second constant need not con-
cern us because neither the bisulfide nor sulfide ion (S~) has
an odor or vapor pressure itself. lonization as in equation (1)
removes the reactive gas from gas-solubility considerations.
Equation (1) gives K, by definition:
(2)
where symbolizes concentration in mol/1.
By rearranging equation (2) and substituting the definition for
pH and pK (analogous to pH), we obtain:
pH = pK1 + log f HS~l/["H2s"j (3)
Equation (3) is the relationship between the pH of a solution
of hydrogen sulfide and the concentrations of the dissolved gas
(H-S) and the bisulfide ion (HS ) in solution.
Defining the total soluble sulfide concentration (before reacting)
as C, and f, as the fraction dissociating at equilibrium, the con-
21
-------
centiraticms become H2S = (1 - f,) C,; HS~ = H+ = f-,C,. Substitut-
ing these values in equation (37 ana taking antilogs:
(f) = 10 exp (pH - pK-/fl + 10 exp (pH - pKl (4)
and
(1 - f^ = l/[l + 10 exp (pH - pK^J (5)
Equation (4) gives the bisulfide ion and (5) the gaseous hydrogen
sulfide fraction for a solution with any total soluble sulfide con-
centration as a function of solution pH. Equations (4) and (5)
thus give the fraction of dissociated and undissociated hydrogen
sulfide, respectively.
Equations (4) and (5) show that at a given temperature, the per-
cent dissociation of a reactive gas is controlled entirely by the
system pH (providing there are no competing reactions) and can be
calculated for chosen values of pH from the pK alone. For hydrogen
sulfide, pK., = 7.02 at 25 °C and thus at a solution pH of 7.02.
(1 - f1) = 1/(1 + 10°'0) = h = 0.5 (6)
When solution pH = pK the solute is 50 percent undissociated
(gas) and 50 percent dissociated (ions) . Increasing acidity (low
pH) will result in higher values of (1 - f,) or undissociated H?S
over wastewater solutions.
AMMONIA EVOLUTION AND pH
The relationship between the evolution of ammonia and pH is analo-
gous to that for hydrogen sulfide. Consider the equilibrium reac-
tion between ammonium ion and gaseous ammonia:
NH4 + J NH3 -I- H+ (7)
If the original concentration of ammonia is C~, and f- is the frac-
tion reacting, at equilibrium we have:
K2 = [NH3J[H+] f [NH4+] (8)
pH = PK2 + log [NH3J/ [NH4+] (9)
f2 = 10 exp (pH - pK2)/j"l + 10 exp (pH - pK2)l (10)
22
-------
where K,, = the equilibrium dissociation constant for ammonium ion.
Equation (10) is analogous to (4) but equation (10) gives the frac-
tion (f~) of undissociated ammonia (gas) present whereas equation
(4) gives the fraction (f,) of dissociated sulfide (ions) present.
SOLUBILITIES OF UNDISSOCIATED GASES
Henry's Law states that the solubility of a gas in a liquid is
directly proportional to the partial pressure of the gas over the
liquid for ideal solutions. Providing there is no reaction be-
tween solute (gas) and solvent (water), Henry's Law should be fol-
lowed reasonably well for the dilute solutions encountered in waste
treatment. Henry's Law may be written:
P = Hx (ID
where P = vapor pressure of gas in equilibrium with solution
H = Henry's Law "constant," pressure per mol fraction,
usually atmospheres/mol fraction
x = mol fraction of undissociated solute in the liquid phase.
Equation (5) provides the fraction of total soluble sulfide present
in solution as undissociated (gaseous) H S as a function of pH and,
coupled with a knowledge of the total soluble sulfide concentration
(C,), can be used to calculate the mol fraction of gaseous hydro-
gen sulfide in solution:
(l-f,)C,/32.06
1 X (12)
1 (l-f1)C1/32.06 + (s.g.)106/18.02
where x = mol fraction hydrogen sulfide gas in solution
(l-f,j = fraction of total sulfide present in solution as
gas
C, = total soluble sulfide concentration in solution,
mg/1
s.g. = specific gravity of water at temperature, t.
Substituting (5) into (12) and the result into (10), we have:
exp(pH-pK, )] ] C,/32.06
£J-J ±— , atm
exp(pH-pK, )1? C,/32.06 + (s.g.)10 /18.02
1J3 1 (13)
From (13) one can estimate the concentration of gaseous hydrogen
sulfide (C ) in the air over the wastewater at constant tempera-
ture, sincef at one atmosphere:
C , = 10 (P.. ,,/l.Q), vol
gl H2S
23
-------
*Cgl = lo(32-06/29-°)pH s/1-0/
-------
pK2 = 0.2401 + 4756/T + 41097/T'
[20)
The pK's of ammonium ion and hydrogen sulfide decrease with in-
creasing temperature. Thus the K's of NH. and H2S increase with
increasing temperature and equations (1) and (7) are forced to the
right.
) and (7) , one can see that H2S tends to
whereas NH.. tends to be formea from the
Referring to equations
dissociate into HS + H
dissociation of NH. into NH., + H as the temperature increases
(that is, as the respective K's increase). Thus these effects
are opposite, and increasing temperature at constant pH increases
the proportion of NH gas in solution but decreases the proportion
of H2S gas. Figure Z, a plot of the fraction undissociated gas
(for both H_S and NH..) versus pH for several temperatures, shows
this effect graphically. Referring to Figure 2 at pH 7, H2S is
about 75 and 50 percent undissociated at 40 and 80 F, respectively
whereas at pH 10, NH is about 55 and 85 percent undissociated at
40 and 80 °F, respectively.
LABORATORY RESULTS
A series of laboratory studies concerning hydrogen sulfide pro-
duction in anaerobic lagoons was conducted by Gloyna and Espino
(1969) . Their model was based on units 58 cm in diameter and 175
cm deep. Illumination was provided 12 hours daily. Four indepen-
dent variables were investigated: organic surface loading rate,
detention time, surface loading rate of sulfate, and influent
sulfate concentration. Results are shown in Table 4. Based
upon these data, an empirical relationship of the following
form was devised:
S = a
BOD surface
loading rate,
Ibs/acre-day
SO. influent
concentration,
mg/1
where
_ /detention time,! +
{days j
S= = sulfide concentration, mg/1
a = -0.011
b = 0.025
c - -0.08
d = 3.3
(21;
These coefficients were based on the model they used and a tem-
perature of 25 °C. This equation was further refined to correlate
the data in the form:
S = I 0.0001185 (BOD surface loading rate)
- 0.001655 (detention time) + 0.0553
SO
= (22;
25
-------
1.0
SOLUTION pH
Figure 2. Effect of Solution pH on Fraction Dissolved Reactant
Dissociated (Ionized).
26
-------
TABLE 4. RESULTS OF LABORATORY ANAEROBIC LAGOON STUDIES
TO PREDICT SULFIDE CONCENTRATIONS
(GLOYNA AND ESPINO, 1969)
Test
#
1
2
3
4
6
7
BOD
load1
136
68
136
136
68
136
SO.,
cone. ,
mg/1
23
23
23
206
200
400
SO,,
load1
11
11
23
94
188
188
Detention
time, days
30
30
15
30
15
30
Sulfide
concentrations ,
mg/1
0
0
0
4
6
8
.432
.500
.12
.29
.36
.76
founds per acre-day
Furthermore, Gloyna and Espino (1969) defined the rate of hydrogen
sulfide transfer from the liquid to the atmosphere using the Fickian
relationship:
q = k(c - ceq) (23)
where q - mass rate of exchange
k = diffusion constant
c = hydrogen sulfide concentration
c = hydrogen sulfide concentration at equilibrium.
A series of tests was conducted in model lagoons to measure the
hydrogen sulfide escape rate. Experiments were conducted in
basins 175 cm deep, having a surface area of 188 sq cm. So long
as_pH of the basins was less than 4.5, there was essentially no
HS nor S= to confound the issue. Under these conditions, the
data could be analyzed as follows:
27
-------
-
at ~ v
dc
.„ _ .
^ (25)
In c = In CQ - k|t (26)
where c = hydrogen sulfide concentration, mg/1
c = initial hydrogen sulfide concentration, mg/1
t = time, hr
A = surface area, m
V = liquid volume, m
k = hydrogen sulfide escape rate, m/hr.
The value of the calculated rate was approximately 0.006 m/hr for
tests with low pH, low wind movement, and no waves. Wind effects,
waves or other agitation would be expected to increase k values.
Based upon these experiments and the equations developed, Gloyna
and Espino established design levels of sulfide in the lagoon as
4 mg/1. Detention time or loading rates may be adjusted to meet
this criterion.
28
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SECTION 6
ANAEROBIC LAGOON DESIGN AND OPERATION
The anaerobic lagoon is the treatment process most widely used at
meat and poultry plants. The anaerobic process is especially
suited to the concentrated hot wastewaters from these plants.
The process utilizes anaerobic bacteria, which function in the
absence of free oxygen to break down organic wastes. The lagoon
is usually deep and covered with a blanket of floating sludge.
The anaerobic lagoon has obtained greater than 90 percent BOD
reduction, with highest removals during warm weather. The process
has minimum capital and operating costs, is simple to operate,
and shows visible treatment results; mechanical equipment is not
necessary and treatment processes can withstand the shock load-
ings common to the industry. The anaerobic lagoon has given high
removal efficiency with and without sludge recirculation.
There are two potential problems in the selection of anaerobic la-
goons for meat packing wastes: odor emission, and high ammonia con-
centrations in the effluent. Ammonia is toxic to fish, and fish
kills due to ammonia in meat plant discharges have been documented.
However, reduction of protein to ammonia is a reaction that can-
not be avoided in biological systems. The problem is that the
concentration of ammonia in anaerobic lagoon effluents requires
selection of additional treatment processes to remove the ammonia.
Anaerobic lagoons are designed with a low surface area to volume
ratio to conserve heat and minimize surface re-aeration. Depths of
10 feet or more are desirable. Economic considerations and main-
taining several feet above groundwater usually limit depths to
less than 18 feet. The volume is based on organic loading and de-
signs range from 12 to 25 pounds of BOD- per 1,000 cubic feet with
15 pounds 600^/1,000 cubic feet being common. The anaerobic la-
goon at the Reeves plant in Ada, Oklahoma, has a water depth of
Io feet and an organic loading of 12 pounds BOD^/1,000 cubic feet
(Witherow, 1976). Average removal efficiencies for BOD5, TSS, and
FOG were 92, 84 and 95 percent, respectively.
The parameters used in determining municipal sewer rates are gen-
erally BOD, TSS, and oil and grease. The BOD and TSS concentrations
at the Reeves plant were below 200 mg/1 except on rare occasions
(Witherow, 1976). Oil and grease analyses made on the effluent
29
-------
showed concentrations were well below the 100 mg/1 limit commonly
used by municipalities. The high percent removal and consistency
of effluent concentration from the anaerobic lagoon resulted in an
effluent which would meet common limitations for discharge to a
municipal treatment plant.
Discharge of an effluent with high hydrogen sulfide concentrations
to a municipal system will damage concrete sewers and structures
unless precautionary devices are installed. Hydrogen sulfide,
with its characteristic rotten egg odor, can be detected at low
concentrations. At the demonstration facilities, the sulfate
concentration in the water supply was 4 mg/1 and a hydrogen
sulfide odor could not be detected. Other septic odors could only
be detected within 50 feet of the anaerobic pond in the downwind
direction.
Most of the effluent ammonia concentrations were between 65 and
85 mg/1 at the Reeves plant (Witherow, 1976). The conversion
of protein to ammonia increased the concentration of ammonia three-
fold through the anaerobic pond.
Oil and grease concentrations in the raw waste and effluent of
the Reeves plant averaged 514 mg/1 and 16 mg/1, respectively,
which shows limited loss in the packinghouse and high reduction in
the anaerobic pond (Witherow, 1976). A grease cover did not form
on the anaerobic pond, which indicates grease was being digested
in the pond. Some consideration was given to mixing grease and
straw on the surface of the lagoon to form a cover to reduce heat
loss. This was not done and temperature reduction through the
pond was high during part of the winter when water temperature
dropped to around 10 °C. Insignificant changes in removal ef-
ficiencies were noted during this period. In a colder climate
there are greater advantages for a cover to reduce heat loss and
maintain biological activity.
The anaerobic lagoon can produce an effluent suitable for discharge
to a municipality, but it will not produce an effluent suitable
for discharge into a surface water without further treatment in an
aerobic process. Aerobic processes are those that maintain dis-
solved oxygen in the water.
30
-------
SECTION 7
FIELD EXPERIENCE
In an attempt to identify specifically documented odor problems
related to anaerobic lagoons serving meat packing plants, it was
necessary to contact personnel who have had immediate experience.
No reports were found in the literature which specifically docu-
mented odor problems or their solution.
DOCUMENTATION OF ODOR PROBLEMS
Odors in the proximity of a meat packing lagoon near Sweetwater,
Texas, were made by Dr. John M. Sweeten (personal communication,
Texas A & M University, 1976). In connection with that lagoon,
odor measurements were made utilizing the scentometer. Downwind
of the anaerobic lagoon three readings were made indicating an
odor intensity of 31 dilutions to threshold. The odor was
described as a mixture of normal, musty lagoon odors sparked with
releases of putrid odors whenever large bubbles or mats of scat-
tered floating solids were surfacing. The lagoon at the location
has a volume of 97,000 ft3 and a daily BOD5 input of 310 pounds
for a loading of 3.2 pounds BODs/day/l,000 ft3. This is not a
high loading rate; however, in conjunction with the high sulfate
concentration in the city water (218 mg/1), problems were created.
In this particular case, aerators have been suggested as a poten-
tial remedy.
Odor measurements were also made in the vicinity of an anaerobic
meat packing plant lagoon near Eagle Pass, Texas, (Sweeten, per-
sonal communication, Texas A & M University, 1976). Odor inten-
sities adjacent to the lagoon were 31 dilutions to threshold. At
a distance of 0.75 miles downwind, odors were detectable at a
concentration of two dilutions to threshold.
In discussing an anaerobic lagoon for the treatment of meat
packing plant wastes in New Zealand, Rands and Cooper (1966)
identified "one of the main criticisms of open, large scale,
anaerobic digesters as being the liability arising from the as-
sociation of hydrogen sulfide with digester gas." Other trace
constituents such as mercaptan and amine-type volatiles joined with
hydrogen sulfide to produce a difficult-to-define "pond" odor.
"Uncontrolled meat waste digesters have attracted considerable
attention in New Zealand in the past because of blackened house
paint, sometimes at distances of several miles from the source."
(Rands and Cooper, 1966).
31
-------
At Moerewa, New Zealand, odor control is dependent on as continuous
a scum cover as possible on the sludge pit (Rands and Cooper,
1966). The scum cover effectively blankets all unpleasant odor,
but how much of this is purely physical retention and how much
oxidation of sulfide as gases permeates the porous scum mat is not
yet known. But the latter process appears to play an important
part in reducing gaseous sulfide.
The effectiveness of the scum mat in reducing the escape of hydro-
gen sulfide to the atmosphere was demonstrated by tests carried out
over the surface of the digester using a Drager Gas Detector held
four inches above the water or scum surface. The concentration of
hydrogen sulfide above the scum, which was about one inch thick, av-
eraged 0.35 mg/l/v/v compared with concentrations of 2.0 to 15.0
mg/1 over scum-free areas (Rands and Cooper, 1966).
"Despite many attempts, the collection of a representative sample
of gas reaching the surface of an open digester has so far pre-
sented insuperable difficulties. Any negative pressure used in
collection increases gas evolution and even collection under a bell
jar can encourage increased solution of carbon dioxide. This is
suggested by the analysis of a sample gas collected in this way and
analyzed by the Chemical Inspector, Department of Health, Auckland,
with the results shown in Table 5." (Rands and Cooper, 1966).
TABLE 5. ANALYSIS OF A GAS SAMPLE COLLECTED IN A BELL JAR
OVER AN ANAEROBIC MEAT PACKING WASTE LAGOON
IN NEW ZEALAND
(RANDS AND COOPER, 1966)
Gas Concentration,
percent by volume
Hydrogen sulfide 0.4
Carbon dioxide 7.0
Methane 85.0
Oxygen 0.6
Nitrogen 7,0
and undetermined
32
-------
A continuous record of the concentration of hydrogen sulfide in
the air^was kept at the treatment plant close to the digesters
and sedimentation tanks from March to November, 1965 by a paper
tape sampler using lead acetate-impregnated paper. Another sampler
was placed at the outlet of the oxidation pond to the river and a
continuous record was kept there from March to June, 1965.
The highest concentration was an isolated peak of 0.11 mg/1 but of
the total number of readings at intervals of two hours, 1,897 were
nil and 389 positive with an average of 0.2 mg/1. Similar results
were obtained from the other sampler, although an occasional high
of 0.20 mg/1 at night indicated a local anaerobic "boil" from the
digester under still air conditions.
The experience gained from these records has shown that maintenance
of gas lines, a continuous scum layer on digesters, as little dis-
turbance of the digester surface as possible, and sufficient wind
to disperse odors without disturbing surface scum are important
details of odor-free operation (Rands and Cooper, 1966).
A municipally owned anaerobic lagoon (Monmouth, Illinois) receives
waste from a Swift and Company packing house killing an average
of 8,000 head per day at maximum capacity. This plant discharges
between 1 and 1.5 million gallons of liquid waste per day to a
treatment system with a BOD5 ranging from between 600 to 700
pounds per day. The anaeroBic lagoon has a surface dimension of
400 by 260, which is covered by a hypalon cover. At this plant,
the gas is not utilized; it is burned off as produced.
Mr. Robert Merwin, Plant Operator, indicated they have found it a
successful operation. They do not attempt to store gas beneath the
cover but keep it burned off as produced. Their cover has neither
ropes nor cables but is a free-floating device; the goal is to
have the cover rest directly upon the water. The major problem,
according to Mr. Merwin, is that excess grease and fat tend to form
a scum and stick to the cover.
The cover for the Monmouth, Illinois, anaerobic meat packing waste
lagoon was manufactured and installed by Globe Liner of Long Beach,
California. Mr. Bill Kays of that company reported that Globe
Liner has manufactured and installed over 90 covers and that they
are working satisfactorily. It is his opinion that the success
enjoyed by Globe Liners has been largely due to his company's
special skills both in design and fabrication of covers.
This particular cover is fabricated from a hypalon resin produced
by Dupont and Company of Louisville, Kentucky. Although they
do not serve meat packing lagoons other than the Monmouth, Il-
linois, currently in operation, they have several meat packing la-
goon covers under design. In discussing the cost of hypalon covers
which might be installed, Mr. Kays pointed out that it is diffi-
cult to determine a representative cost; however, he was able
33
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to indicate that the typical cost per square foot for a moder-
ately large lagoon is in the neighborhood of $1.75 to $2.50 per
square foot. This price does not include the gas collection
system nor unusual installation or production difficulties.
According to his recollection, the Monmouth cover was installed
for a cost of approximately $1.90 per square foot three years
ago.
Mr. James Chittenden, Vice-President of Research and Development,
Texas Amarillo Systems Company, was contacted relative to his ex-
perience with respect to meat packing anaerobic lagoon covers.
Mr. Chittenden has been involved with meat packing lagoons for
some time and has been watching the Monmouth, Illinois, operation
with considerable interest. He reports that his firm is currently
designing an anaerobic lagoon to be located in Arizona which will
be provided with a cover for a plant killing 1,400 animals per day.
This plant will utilize water with a sulfate content of 390 mg/1.
It is his design that the lagoon will produce an average of 100
cubic feet per minute of gas having a heating value of 650 Btu/lb.
He anticipates the system will, therefore, be sufficiently large to
justify the purchase of a boiler to utilize the gas for heat
production. Anticipated cost of the cover is to be in the range of
$250,000.
The University of Illinois has used a "Controliner," Model 90,
Environetics Company, as an anaerobic swine manure lagoon liner
and cover for two years (Waldo, 1976). This unit provides total
containment of both liquids and gases. Prior to installation of
the unit, both odor and mosquito problems existed. Periodic
analyses of gases within the Controliner were performed by gas
chromatography and are summarized in Table 6. As the table shows,
methane content of the gas is a sensitive function of temperature.
34
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TABLE 6. COMPOSITION OF GASES INSIDE THE CONTROLINER
AT UNIVERSITY OF ILLINOIS SWINE FARM
(WALDO, 1976)
Constituent, percent
Date
September 1, 1976
September 1 5
October 4
October 17
October 24
December 5
March 19, 1977
April 1
April 23
July 29
co2
34.8
45.0
42.0
18.0
25
5.6
11.7
6.8
50
20
°2
2.5
4.5
2.0
12
4
19
17.2
19.0
9.7
10
N2
20.7
10.5
10.5
45
46
72
71
73
39
49
CH<
42
42
48
25
25
2
4
1
1
21
1
.9
.8
.2
.2
35
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SECTION 8
PROBLEM ANALYSIS
Odors are a complex subjective phenomenon. Odor problems arise
when neighbors or other people who live, work or recreate in
the vicinity of a source of air emissions register complaints or
otherwise bring pressure against an operation. Legal recourse is
available for property owners whose use of their property has been
unreasonably restricted due to odors. Where large groups of people
have been offended, public nuisance suits have been filed seeking
operational restrictions or actual plant closure.
Anaerobic lagoons, which have proven to be low cost effective waste
treatment devices, are especially prone to emit odorous gaseous com-
pounds. By its very nature, the anaerobic process degrades complex
organic compounds in the absence of oxygen to less complex com-
pounds of increasing volatility. Both the end products and inter-
mediate breakdown products contribute to odor production. Odor
problems have been observed to be more severe when the water supply
has a high sulfate concentration. This observation suggests hydro-
gen sulfide and related sulfur-bearing compounds are important
in the observed odor intensities.
In discussing odors from anaerobic lagoons serving meat packing
plants, J. A. Chittenden (1977) made the following comments:
1. No anaerobic lagoon should be used if the sulfate concen-
tration of incoming fresh water is in excess of 200 mg/1.
As a matter of fact, I am reluctant to consider anaerobics
at sulfate concentrations above 100 mg/1. The hydrogen sul-
fide generated by the anaerobic action of concentrations
above 100 mg/1 produces odors that travel for miles down-
wind of the treatment system.
2. The loading on the anaerobic should range from 15 pounds
BOD/1,000 ft3 to 25 pounds BOD/1,000 ft3. Loading signifi-
cantly out of the range, either higher or lower, results in
poor anaerobic lagoon performance. This imposes a high
load on the subsequent aerobic phases, causing these to
become septic and generate odors.
3. Start-up of the anaerobic lagoon remains a black
art. No one system is quite like another. There are
several things to watch and consider.
36
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a. I see the anaerobic at start-up with primary digester
sludges from a municipal treatment system. This helps
get suspended solids up at start-up and appears
to give the bugs a headstart. Forty or fifty thousand
gallons of sludge is not too much.
b. In one case the acid-forming bacteria predominated
during start-up and the methane-forming bacteria could
not get started. As a result, pH dropped to around 5.0
rather than the near 7.0 pH realized from a well-
functioning anaerobic lagoon. Several additions of
the stoichiometric amount of lime were required to
overcome the acid formers, but inside of a week the
methane formers began to function and BOD fell into
the desired range.
c. The sludge cover on the anaerobics forms, in my opinion,
as a result of the flotation effect from the gas formed
during anaerobic decomposition. Sufficient gases are
not generated until the suspended solids environment
in the bottom strata of the anaerobics is well-established.
This takes time—as much as four months in cold weather.
Bypassing grease recovery systems does nothing to en-
hance cover formation. I have had some limited success
in promoting cover formation by flowing chopped straw on
the surface of the lagoon. The straw sinks after three
or four weeks and must be re-applied, but it does help.
The comments made by Mr. Chittenden typify current odor control tech-
nology. There has been very little research done having direct
odor control objectives. Much of the knowledge about odor control
from anaerobic meat packing wastes has been a spin-off from waste
treatment studies.
As indicated earlier, problems result when the following odor pro-
duction steps occur:
1. Odorous compounds enter or are formed in the anaerobic
lagoon.
2. Odorous compounds existing in the lagoon volatilize and
escape to the overhead air.
3. Once free to the air over an anaerobic lagoon, the odorous
gas mixture must be transported downwind to a location where
it is judged offensive or otherwise undesirable. This
transport must occur so the odorous air arrives at the
point of objection before it has been diluted beyond the
threshold concentration, oxidized to non-odorous species,
absorbed by intervening vegetation or structures, or
reacted with other airborne compounds to attenuate its
odorous nature.
37
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The above odor production steps provide the basis for most odor
control procedures. Possible odor control alternatives are
outlined as follows:
1. Prevent entry or formation of odorous components
Pretreatment with chemicals to remove or tie
up odorous precursors - sulfur
Inhibit anaerobic decomposition
Aeration
Sterilization
Alter environmental conditions to prevent the
formation of odorous components
2. Prevent the escape of odorous components
Maintain an effective scum layer
Install an impermeable cover
Chemically treat to prevent volatilization
Precipitation
pH adjustment
3. Prevent transport of volatilized odorants from lagoon
to neighbors
Use of vegetative barriers
Use of scrubbing screens
Select lagoon site remote from habitation and
recreation sites
38
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SECTION 9
RESEARCH NEEDS
Odors from anaerobic lagoons used in the treatment of meat packing
wastes are a significant environmental problem. In areas where
lagoons are used/ odors present a nuisance problem resulting in
citizen complaints and property damage. In other locations, an-
aerobic lagoons are rejected in the design process, forcing the
selection of more expensive and energy-intensive processes.
The control of anaerobic lagoon odors offers an opportunity for
technology application with measurable pay-off. Research tech-
niques have been devised which have the needed sophistication to
make significant contributions.
Among the specific needs are the following:
Identification of the specific compound with the goal of
identifying means of eliminating it from water and air.
Identification of potential chemical treatment processes for
removing or precipitating odorous components.
Evaluating means of forming scum layers using synthetic mate-
rials as well as low-density waste components.
Measuring the effectiveness of various scum layers in terms
of thickness and composition.
Evaluation on a significant size scale of various cover mate-
rials and fabrication techniques to achieve a minimum cost
system with appropriate useful life and resistance to physical
and chemical damage.
Evaluation of physical and chemical processes involved in
odorous compound transport with the goal of effectively de-
signed odor control barriers.
39
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REFERENCES
Amoore, J. E. 1963. Stereochemical Theory of Olfaction. Nature
198:274.
Amoore, J. E., G. Palmer, and E. Wauke. 1967. Molecular Shape
and Odor: Pattern Analysis by PAPA. Nature 216:1084.
ASTM. 1968. Manual on Sensory Testing Methods. American Society
for Testing and Materials STP No. 434.
Baker, R. A. 1964. Response Parameters Including Synergism-
Antagonism in Aqueous Odor Measurements. Annals of the
New York Academy of Science 116(2):495.
Earth, C. 1970. Why Does It Smell So Bad? Paper No. 70-416.
American Society of Agricultural Engineers, St. Joseph, MI
49085. 16 pp.
Burnett, W. E. 1969. Qualitative Determination of the Odor
Quality of Chicken Manure. pp. 2-17. In: Odors, Gases and
Particulate Matter from High Density Poultry Management Systems
as They Relate to Air Pollution. Final Report, Department of
Agricultural Engineering, Cornell University. Contract No.
C-1101.
Chittenden, J. A. 1977. Control of Odors from Anaerobic Lagoons
Treating Meatpacking Wastes, pp. 38-61. In: Proceedings,
Eighth National Symposium on Food Processing. EPA-600/2-77-184.
Davies, J. T. and F. H. Taylor. 1954. A Model System for the Ol-
factory Membrane. Nature 174:693.
Dean, J. A., ed. 1973. Lange's Handbook of Chemistry. llth Edition,
McGraw-Hill.
Dyson, G. M. 1938. The Scientific Basis of Odour. Chem. and Ind.
57:647.
Gloyna, E. F. and E. Espino. 1969. Sulfide Production in Waste
Stabilization Ponds. In: Proceedings, American Society of
Civil Engineers. J. San. Engr. Div. SA3:607.
40
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Guadnagni, D. B., R. G. Buttery, S. Okana, and H. K. Burn. 1963.
Additive Effect of Sub-Threshold Concentrations of Some Or-
ganic Compounds Associated with Food Aromas. Nature 200:1288.
Huey, N. A., L. C. Broering, G. A. Jutze, and C. W. Gruber. 1960.
Objective Odor Pollution Control Investigations. J. Air Poll.
Control Assn. 10:441.
Leonardos, G., D. Kendall, and N. Barnard. 1969. Odor Threshold
Determinations of 53 Odorant Chemicals. J. Air. Poll.
Control Assn. 19(2):91.
Moncrieff, R. W. 1966. Odour Preferences. John Wiley, New York.
p. 89.
Moncrieff, R. W. 1967. The Chemical Senses. Leonard Hill, London.
p. 44.
Moulton, D. G. 1965. Physiological Aspects of Olfaction. J. Food
Science 30:908.
Paulson, D. J. 1967. Commercial Feedlots—Nuisance, Zoning and
Regulation. Washburn Law Journal 6:493-507.
Pomeroy, R. D. and H. Cruse. 1969. Hydrogen Sulfide Odor Threshold.
J. Amer. Water Works Assn. 61(12) :677.
Rands/ M. B. and D. E. Cooper. 1966. Development and Operation of
a Low Cost Anaerobic Plant for Meat Wastes. pp. 613-638. In:
Proceedings, 21st Purdue Industrial Waste Conference, Lafayette,
Indiana.
Rosen, A. A., J. B. Peter, and F. M. Middleton. 1962. Odor Thresh-
olds of Mixed Organic Chemicals. J. Water Poll. Control Fed.
34:7.
Rowe, N. R. 1963. Odor Control with Activated Charcoal. Air Poll.
Control Assn. 13:150.
Sobel, A. T. 1971. Olfactory Measurement of Animal Manure Odors.
Proceedings, Agricultural Waste Management and Associated Odor
Control, Cornell University. AWM 71-04.
Stahl, W. H., ed. 1973. Compilation of Odor and Taste Threshold
Values Data. ASTM Data Series DS 48, Philadelphia. pp. 104-
130.
Waldo, D. A. 1976. An Evaluation of an Environetics Controliner.
Unpublished Special Report. Advisor D. H. Vanderholm, Depart-
ment of Agricultural Engineering, University of Illinois.
16 pp.
41
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White R. K., E. P. Taiganides, and C. D. Cole. 1971. Chromato-
graphic Identification of Malodors from Dairy Animal Waste.
pp. 110-113. In: Proceedings, Livestock Waste Management and
Pollution Abatement. American Society of Agricultural Engi-
neers, St. Joseph, MI 49085. ASAE Publication PROC-271.
Witherow, J. L. 1976. Waste Treatment for Small Meat and Poultry
Plants: An Extension Application. ASAE Paper No. 76-6008.
Presented at the 1976 Annual Meeting, American Society of
Agricultural Engineers, June 27-30. 18 pp.
WPCF. 1969. Safety in Wastewater Works. Manual of Practice No. I.
Water Poll. Control Fed. Washington, DC.
Wright, R. H. 1966. Why Is An Odour? Nature 209:551.
42
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APPENDIX
RESEARCH PROPOSAL
One objective of this report preparation was to identify research
needs in the control of odors from food processing lagoons. The
proposal generated was submitted to the Environmental Protection
Agency in September, 1977.
Title: Development of a Permeable Cover to Control Odor
Principal Investigator: Dr. J. Ronald Miner, Professor and Head
Department of Agricultural Engineering
Oregon State University
Corvallis, Oregon 97331
Telephone: 503 754-2041
Project Period: 2 years
Budget: $66,800
OBJECTIVES OF THIS PROJECT
This project has as its overall objective the development of infor-
mation which will allow the design and construction of a floating
permeable cover to be placed on odorous liquids to reduce or
eliminate the escape of odorous gases. Although the need for
and application of this information is widespread, it has par-
ticular application to odor problems in the meat processing
and livestock production industries. Anaerobic lagoons and,
consequently, odor problems are also of concern in fruit and
vegetable processing plants, dairies, potato processing plants
and rendering facilities. Permeable covers have the potential
of being a satisfactory solution to odor problems wherever odor-
ous liquids are stored in open tanks or reservoirs.
Anaerobic lagoons are a low cost technique for the treatment of or-
ganic wastewaters. They typically achieve 70 to 85 percent BOD
reduction at a very low level of energy consumption. Certain in-
dustrial and commercial wastes are particularly amenable to this
form of treatment including those discharging a warm water with a
high BOD concentration. Frequently, however, the use of anaerobic
lagoons is rejected in favor of more expensive and energy-consump-
tive techniques due to the inability to control odor releases.
43
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Odor problems are particularly severe from anaerobic lagoons
in which sulfate ion concentration of the untreated waste is in
excess of 100 rag/1.
The overall objective will be approached by pursuit of the first
three of the following four procedural steps:
1. Develop criteria for a permeable cover to control
odor emissions from an anaerobic liquid surface.
2. Investigate various materials such as foams, beads,
natural zeolites and other inert buoyant materials from
which one might fabricate a floating lagoon cover.
3. Evaluate the cost effectiveness of floating permeable
covers as a means of odor control from anaerobic liquid
surfaces.
4. Demonstrate the effectiveness of floating permeable covers
in an existing odorous lagoon.
RESULTS AND BENEFITS EXPECTED
This project is designed to provide a cost effective technique for
the control of odors from anaerobic lagoons and other anaerobic
liquid surfaces. The only alternatives currently available are
expensive impermeable covers which encase the entire lagoon
surface and require a separate gas treatment scheme or abandonment
of the anaerobic lagoon process in favor of more expensive and/or
energy-intensive processes such as aeration basins, aerated
lagoons, or automated anaerobic digesters.
The most obvious benefit is decreased odor in the proximity of
anaerobic lagoons; however, the real benefits are in the area of
wastewater treatment. By making open anaerobic treatment pro-
cesses environmentally acceptable, the cost of wastewater treat-
ment is reduced, hence, high levels of BOD removal become econom-
ically achievable. Furthermore, since anaerobic lagoons require
considerably less energy input than alternate forms of treatment,
development of an effective odor treating cover has a significant
impact upon the energy consumption of environmental quality
protection.
Beyond direct application of these research results to the food
processing, livestock production and other concentrated organic
waste-generating industries, these research activities are of a
sufficiently basic nature to have widespread application wherever
it is desirable to control organic gas escaping from liquid
surfaces. The theory and practices involved will have an impact
on the art of pollution abatement. Due to the proposed involve-
ment of graduate and undergraduate students, there will also
be measurable educational benefits.
44
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APPROACH
The proposed project is consistent with previous work of the prin-
cipal investigator and represents a timely progression of his pre-
vious work. The attached list of publications reflects the nature
of his previous research relative to odor control technology.
The^timeliness of this work is further supported by current
environmental and social concern over odor and other nuisance
pollutants.
Background
Anaerobic lagoons have been demonstrated to effectively reduce
organic pollutants. They accomplish this removal with minimum
capital and operating costs. They are simple to operate, require
no mechanical equipment, and the process can withstand shock load-
ings. In meat packing plant waste treatment, Chittenden et
al. (1) report BOD, grease and suspended solids removals in excess
of 80 percent. Similar removal efficiencies have been reported in
the treatment of other wastewaters. The major disadvantage of
anaerobic lagoons is the odor resulting from the process, which
can be particularly severe when sulfate concentration in the
water supply is high. Wherever sulfate concentrations are in
excess of 100 mg/1, odor problems are a subject of concern.
Specific case histories in which odor problems were encountered
from meat processing lagoons were reported by Chittenden et al.
A similar accounting of odor problems from livestock production
was provided by Miner (2).
Costs of using an anaerobic lagoon or aeration were compared
for a 2.88 mgd waste flow meat packing plant in Illinois (1).
The anaerobic-aerobic combination was approximately $1.4 million
less expensive to build than a completely aerobic system. A float-
ing flexible membrane to cover with a gas burner was proposed at
an additional cost of $369,000. Thus, if an effective permeable
cover can be developed at a cost of $3 per square foot or less, a
net initial cost saving can be accomplished.
There is ample evidence in both the literature and common experi-
ence to support the basic premise of this proposal: namely, that
slow diffusion of odorous gases through either a chemically or
biologically active layer will result in absorption and oxidation
of odorous demonstrations in normal experience, including the
lack of perceptible odors over buried putrescible wastes or
over septic tank disposal fields.
The use of soil beds for odor control was reported by Carlson and
Leiser (3). 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 possibilities. Over a three-month test per-
iod, hydrogen sulfide gas concentrations of 15 ppm at a flow rate
45
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of 0.35 ft /min per square foot of soil surface were reduced to an
imperceptible level in 32 inches of soil. For a flow rate of 0.34
ft /min per square foot in a hydrogen sulfide concentration of 9.5
ppm, 90 percent of the hydrogen sulfide was removed in the first
18 inches of soil. Effectiveness of soil beds in removing hy-
drogen sulfide did not diminish during a three-month test period.
A soil filter for the removal of odors from a Mercer Island,
Washington, pumping station has been in successful operation for
several years.
As an outgrowth of the earlier work, Carlson and Gumerman (4) pro-
posed a system for the treatment of odorous gases. Their system
included a perforated tile system through which 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 sacrificed in the active biological growth that
occurred. They suggested a plant with a shallow root system which
would meet the above goals but not interfere with the gas dis-
tribution piping system.
The use of soil filters for the removal of animal waste odors was
investigated by Burnett and Dondero (5). They based their initial
trials on the earlier work of Carlson and Leiser (3) and Gumerman
and Carlson (6) and found that, indeed, the use of soil columns
was effective in removing both hydrogen sulfide and ammonia from
the headspace gas over decomposing poultry manure. They found that
for ammonia concentrations of up to 200 ppm, removals of 100
percent were obtained, and for hydrogen sulfide concentrations
of 22 to 100 ppm, more than 95 percent removal occurred throughout
a three-month continuous testing period. They further found
that when the soil columns dried, ammonia removal efficiency
dropped rapidly. Thus, to be fully effective, the moisture
content of the soil must be maintained. By mixing manure with
soil prior to using it in the column, the moisture-holding capa-
city was increased. As a result of this 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
two feet deep, two feet wide and 903 feet long would be required
to deodorize the air. This is equivalent to 0.0903 cubic feet
of soil per bird.
REFERENCES
1. Chittenden, J. A., L. E. Orsi, and J. L. Witherow. Control of
Odors from an Anaerobic Lagoon Treating Meat Packing Wastes.
Proceedings/ Eighth National Symposium on Food Processing
Wastes. Seattle, Washington. 1977.
2. Miner, J. R. Odors From Confined Livestock Production.
Environmental Protection Technology Series. EPA-660/2-74-023.
125 pp. 1976.
46
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3. Carlson, D. A. and C. P. Leister. Soil Beds for the Control
of Sewage Odors. J. Water Poll. Control Fed. 34:829-840.
1966.
4. Carlson, D. A. and R. C. Gumerman. Hydrogen Sulfide and
Methyl Mercaptans Removals with Soil Columns. Proceedings,
21st Industrial Waste Conference. Purdue University, Lafay-
ette, Indiana. 1966.
5. Burnett, W. E. and N. C. Dondero. The Control of Air Pollu-
tion (Odors) from Animal Wastes - Evaluation of Commercial
Odor Control Products by an Organoleptic Test. Paper No.
68-909. American Society of Agricultural Engineers. De-
cember, 1968.
6. Gumerman, R. C. and D. A. Carlson. Chemical Aspects of Odor
Removal in Some Soil Systems. pp. 292-302. In: Animal Waste
Management. Cornell University Conference on Agricultural
Waste Management. 1969.
WORK PLAN
The first step in this project is evaluation of the basic process
which will be accomplished by fabricating circular pads of dense
fiberglass filter materials ranging in thickness from one to
six inches. They will be fabricated into a circular configuration
to fit snugly inside the plastic lined 55-gallon drums proposed
for simulating the lagooning process. Twelve barrels will be
used initially. They will be filled with cattle manure for the
first trial, then with a simulated meat packing plant waste for
the second. For both trials, one-third of the barrels will be
spiked with sulfates to provide a net sulfate ion concentration of
100 mg/1 and an equal number to 300 mg/1. Effectiveness will be
evaluated by measuring the ammonia and hydrogen sulfide evolution
rates and by scentometer evaluations made at the rim of the barrel.
Based upon the results of the initial trials, alternate techniques
of fabricating permeable lagoon covers will be evaluated. The
materials discussed in the detailed objectives will be included.
The goal during this phase of the effort will be to identify those
basic physical characteristics which define the effectiveness of a
lagoon cover; however, there is likely an additional factor re-
lating to the distance of travel by the gas phase. Once these
questions are resolved, covers made of different materials with
standard levels of odor abatement can be defined. From this
point, it is possible to calculate the cost effectiveness of
alternate designs. The next ingredient is the long term use-
fulness of specific covers, which will be determined using the
model lagoons described above. The schedule for accomplishing
the various tasks is shown in Figure 1.
47
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FIGURE A-l. TIME SCHEDULE FOR PROGRESS OF THE PROJECT
First year (quarters) Second year (quarters]
1
2
3
4
1
2
3
4
Assemble personnel & equipment
Train staff & design initial covers
Evaluate standard covers
*»
00
Prepare first year report
Design alternate covers
Evaluate alternate covers
Identify site for field test
Prepare design for field test
Prepare final report
-------
REVIEWS
The proposal was evaluated by six technical reviewers who have
extensive experience on the subject. A summary of this review
follows.
Mr. //// /. ///////// of the Environmental Protection Agency, aided
the development of this proposal over the year and had previous-
ly developed a research proposal with similar, but less extensive,
objectives. He finds the overall project design, available re-
sources, project period, and budget satisfactory. He states the
principal investigator's background and experience are ideal. His
concerns are the brevity of the design and the developmental nature
of the project. This development requires exploration for more
effective material for odor reduction.
Dr. /. /. ///, Agricultural Engineering Professor at the /////////
// ///////// was selected at random to review the proposal. He
states that the project's objectives are of interest to the EPA
mission and that the project could contribute significantly in
control of odor and use of low cost waste treatment. He knows
of no overlap of the proposed project with other work, but men-
tioned that some research on alternate control techniques has been
undertaken. He states that the project period, resources, and
facilities are adequate, and that the principal investigator
has the needed background and training and has a long successful
record of research in the area. Dr. /// makes two suggestions:
(1) the model lagoon should be operated through a range of ex-
pected temperatures for expected seasonal variations, and (2)
continuous loading and discharge of waste be used in the exper-
iment to more nearly simulate actual conditions.
Dr. //// /. ///////, Dean, College of Engineering, ////////// //
/////////// was asked to review the project because of his research
in odor control using soil systems. Dr. /////// accurately des-
cribes the objectives and recommends the area of work. He states,
"Not a great deal of work has been done in the area proposed." He
describes the budget as sufficient to get the project under way and
states a second stage (year) of work should be undertaken if pro-
gress shows worthwhile results. He further states a third stage of
field evaluation is needed if the developed system is feasible.
Dr. /////// writes the background information is reasonable, but he
would like more details on the proposed work. He later states such
project details could not be expected until the principal investi-
gator has funds sufficient to allocate time to the project. He
has several specific concerns or suggestions. These are: (1)
use of 55-gallon drums for digesters will cause problems "because
of iron, temperature, current, and depth perturbations"; (2) the
development of a permeable cover should include more materials of
a biologically active or amenable base; the possibility for a joint
soil-glass fiber system or a styrofoam log with soil interface sys-
tem for breathing of odorous gases is suggested.
49
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Dr. /// ///////, Extension Agricultural Engineer, ///// ////////////
///////// ///////, was selected to review the proposal because of
his publications and experience in control of odors from anaerobic
lagoons and feedlots. Dr. /////// strongly recommends that EPA
fund this grant, which will provide significant information on the
control of odors. He noted that in his state, 45 percent of all
air pollution complaints involve odors, and that anaerobic lagoons
are an efficient and cheap method of waste treatment, but are often
the leading cause of odors found around livestock feeding opera-
tions. Dr. /////// writes, "No organized research has yet dealt
with the use of permeable covers as a means of odor abatement." He
thinks "a permeable floating cover for lagoons is a unique approach
widely applicable to thousands of existing feeding operations."
He states the principal investigator is one of the best qualified
researchers in the U. S. to conduct an investigation of the type
proposed. He feels the two-year project period and the budget are
appropriate, finds no major weakness with the proposal, and lists
as one of its strong points the use of plastic-lined 55-gallon
drums to simulate lagooning.
Mr. /. /. //////////, Vice-President for Research, /////, has been
responsible for design of a number of meat packing waste treatment
systems for a large meat packer. He writes that the project is
sound and the benefits to EPA appreciable. He describes anaerobic
lagoon operations and lists three specific benefits of the project
to these operations: (1) it would allow the use of anaerobic la-
goons treating waters with sulfate concentrations above 100 mg/1;
(2) it would be beneficial during the start-up period of an an-
aerobic lagoon when odorous emissions are commonly experienced
regardless of sulfate concentrations; (3) it would be useful in
case of intermittent loading to the anaerobic lagoon due to sea-
sonal operation of the plant (common in the food industry).
The benefits would be not only to control odor by maintaining
a cover during plant shutdowns, but also during re-introduction
of waste. He knows of no similar work being conducted, except
on impermeable covers (which he describes as too costly, except
in the case of very high sulfate waters). He thinks the staff,
support facilities, project period, and project budget are ade-
quate. The strengths of the project are the use of 55-gallon
drums as digesters, the use of 12 digesters, and the range of
sulfate concentrations at 1, 100, and 300 mg/1. The weakness
of the project is finding an acceptable medium to act as a per-
meable cover. He suggests that insulated thermostatically con-
trolled barrels (drums) be used to maintain constant temperature
and constant gas production. He states that even if the project
fails to produce an acceptable cover material, demonstrating
a relationship between odor emissions and surface area per unit
of cover would justify this study.
50
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Mr. /. /. //////, Research Chemist with the //////// ///////
//////// /////////// ///., New Zealand, was requested to review
the project because of his two publications on the subject.
////// repeats the objectives without describing their benefits.
His seven page review includes description of his research and ob-
servations, as well as that of others, on the subject. The more
pertinent points follow. The length of operation necessary to form
a scum crust and become odor-free varies between 4 and 12 months.
These crusts may reach one to three feet in thickness, and at
one anaerobic lagoon, cleaning was necessary every six months
to a year. (These conditions usually occur when paunch manure
is discharged to the lagoon). At another anaerobic lagoon, a
1/4- to 1/2-inch crust was maintained for odor control and acted
as a biological filter with action due partly to iron bacteria
in symbiotic association with red and green photosynthetic sulfur
bacteria. He states that the proposed use of a cheap porous
material may be necessary to form a satisfactory scum mat for
odor control and suggests the addition of cattle and sheep paunch
material (a practice strongly opposed by EPA and cost factors
since the presence of BPT and BAT discharge limitations).
Mr. ////// writes the proposal gives a well-rounded approach and
that the materials listed are worth investigating. He ranks the
principal investigator as high caliber, and the organization and
support facilities as ideal. The project period and budget are
adequate, but he suggests the project time could be longer. He
considers the central theme a valid one and recommends selecting
materials for the cover that can be easily removed and replaced.
He continues saying that on large lagoons when sludge buildup or
maintenance is needed, a dragline is a simple means of solids
removal, and for this reason a non-rigid cover material would be
better. He concludes that use of 55-gallon drums is sound and
generation of a fibrous cover can stop odors.
51
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TECHNICAL REPORT DATA
rcaJ iii^trui'tions on the reverse before completing)
1. R I PORT NO.
EPA-600/2-78-151
4. Fl T Lfc AND SUBTi TLE
Control of Odors from Anaerobic Lagoons Treating
Food Processing Wastewaters
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(o)
J. Ronald Miner
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Agricultural Engineering Department
Oregon State University
Corvallis, Oregon 97331
12. SPONSORING AGtNCY NAMt AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
3. RECIPIfc'NT'S ACCESSION-NO.
5 REPORT DATE
July 1978 issuing date
10. PROGRAM ELEMENT NO.
1AB60U
11. CONTRACT/GRANT NO.
CC691935-J
13. TYPE OF REPORT AND PERIOD COVERED
7/1/76 - 12/31/76 Finai
14. SPONSORING AGENCY CODE
EPA/600/12
15, SUPPLEMENTARY NOTFS
Project Officer: Jack L. Witherow, Food and Wood Products Branch--Corvallis, Oregon
16. ABSTRACT
Anaerobic lagoons are used for the treatment of meat packing wastes in most area of
the country. They are a relatively low cost means of achieving BOD reduction.
Although lagoon effluent is not suitable for stream discharge, it is amenable to
further treatment or to land application. One of the most serious limitations of
anaerobic lagoons in this application is odor production. Odor complains have
been widespread but have been most frequent in areas of high sulfate waters and
during start-up. There has been little specific research effort devoted to anaerobic
lagoon odor control. This report assembles existing information relative to odor
control associated with anaerobic lagoons used in the meat packing industry and
identifies opportunities for productive research. It provides a basis for approaching
the overall problem in a comprehensive fashion. This report was submitted in
fulfillment of Contract No. CC691935-J by the Agricultural Research Foundation of
Oregon State University under the sponsorship of the U. S. Environmental Protection
Agency. It covers the period July 1, 1976 to December 31, 1976, and work was
completed as of December 31, 1976.
Odors
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTOR:; h.IDENTIFIERS/OPEN ENDED TERMS
Anaerobic Lagoon
Meatpacking
Food Processing Industry
Anaerobic Digestion
Wastewater Treatment
[Jl.j F RIHU riON STATEMENT
RELEASE TO PUBLIC
19 ^FCURITY CLASS ( This Report)
UNCLASSIFIEJD
20 SECURITY CLASS (Hits page I
UNCLASSIFIED
c. COSATI I ifld/Oroiip
13B
21. NO. OF PAGES
60
22. PRICE
EPA Form 2220-1 (9-73)
•/, U. S. GOVERNMENT PRINTING OFFICE: 1978-757-140/1369 Region No. 5-||
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