Farming, Saturday, December 2,2000
FIELD TESTING
OF ODOR REDUCTION
TECHNOLOGIES ON
SWINE OPERATIONS
PROGRESS REPORT
Introduction
Urban-rural conflict over
large-scale animal agriculture
has become commonplace
during the past several years. In
particular, odors from large
swine operations have caused
neighbors to complain that they
can not enjoy their homes and
lives. However, commercial
swine producers are reluctant to
invest in technology that is often
expensive and unproven.
The following study was un
dertaken, with support from the
College of Agricultural Sciences
at Penn State, and grants from
the Pennsylvania Department of
Agriculture. In addition, cooper
ating farms and companies also
contributed time and equipment
to these projects.
Objectives
1. Determine the effectiveness
and manageability of three odor
reducing strategies on selected
swine operations in Pennsylva
nia.
2. Determine physical and
personal factors affecting odors
scores recorded by neighbors of
swine farms.
3. Determine how neighbors
and nonneighbors of swine
farms perceive large livestock
operations.
Procedures
In the summer of 1999, re
searchers at Penn State, with fi
nancial support from the
Pennsylvania Department of
Agriculture, sought to include
neighbors in evaluating three
economical strategies for reduc
ing odor complaints from hog
farms.
Odors on hog farms arise
from three sources: land appli
cation of manure, manure stor
age, and air exhausted from the
buildings. In this study,
researches attempted to control
odors from either air or outside
manure storage structures, but
not odors associated with
spreading manure.
Three odor control techniques
were evaluated: biofiltration of
exhausted air, dust filtration of
exhausted air, and floating
biofilters (chopped straw) for
outdoor manure storage struc
tures.
Farms for the project were se
lected based on the practicality
of applying the technologies at
the specific site, a history of odor
conflict in the neighborhood,
and operator’s willingness to co
operate with the researchers.
Biofiltration Farms
Two 2,000 and one 4,000-pig
finishing operation were se
lected to evaluate biofdtration of
exhausted air. Each pit fan
(which discharges gases from
the under-building manure stor
age) on all'buildings was fitted
with a biofilter. Additionally,
two of the buildings were
equipped with a larger biofilter
to capture some of the ex
hausted air from end wall fans
that ventilate the living space
for the pigs.
Biofilters were constructed of
a layer of wooden pallets lying
on the ground covered by a layer
of plastic mesh and an eight to
12-inch-deep mixture of finished
compost and wood chips. Air ex
hausted from the building was
forced under the pallets and al
lowed to filter through the com
post and wood chip mixture.
Bacteria in the compost mixture
capture and break down odor
causing compounds. Biofilters
require about 80 square feet per
1,000 cubic feet per minute of air
moved through the building, so
this technology was limited to
smaller operations because of
physical space requirements.
Dust Filtration Farms
Three fairly large operations
were selected for implementing
dust filtration technology: one
2,800-sow farrow-to-feeder pig
farm, one 1,400 farrow-to-feeder
pig farm, and one 10,000-pig
finishing site.
On these farms, plastic mesh
(shade cloth used in the green
house industry) was fashioned
into a “windsock” and placed
over each fan shroud. It was
hoped that the windsocks would
cause odor-carrying dust parti
cles to settle more rapidly. Addi
tionally, the socks could
potentially disrupt the exhaust
stream and help odors to dilute
more quickly.
Floating Biofilter Farms
One 300-sow farrow-to-feeder
and one 450-sow farrow-to
finish operations were selected
for the third technology a float
ing biofilter of chopped straw
for outside manure storage
structures. A commercial land
scape seeder was hired to apply
an eight-inch covering of
chopped straw over the open,
outdoor manure storage struc
tures on each farm. Odors escap
ing from the manure storage
structures are filtered by the
layer of straw in the same
manner as that of biofilters con
nected to exhaust fans.
Evaluation
To evaluate the success of
each of the odor reduction tech
nologies, all neighbors within a
variable radius (generally less
than one mile) of seven of the
farms were contacted by mail
prior to commencement of the
project. Each neighbor received
a survey about their perceptions
of animal agriculture and other
information. In addition, each
household received six odor
evaluation cards one card to be
used each week for a six-week
period. The survey included a
map of the area and neighbors
were asked to mark the location
of their homes on the map and
return the surveys immediately.
The odor evaluation cards were
to be filled out each day between
the hours of 6 p.m. and mid
night. Odor was evaluated on a
scale of zero (no odor) to five (in
tense odor). One of the farms
with a straw cover was located
near a heavily traveled road, but
had few close neighbors. Em
ployees of a local business who
regularly traveled the road were
contacted to evaluate odor from
that site during their drive to
and from work.
Approximately midway
through the six-week evaluation
period, the odor control techno
logies were installed so odor
scores could be compared before
and after technology applica
tion. Producers at all farm sites
were asked to refrain from
spreading manure during the
period of the study so neighbors
would not confuse spreading
odors with odors emanating
from the site.
During the same time frame,
nonneighbors who lived in simi
lar rural settings, but not near
large livestock facilities, were
identified. These individuals
were asked to complete surveys
similar to those sent to the
neighbors, but without the odor
evaluation cards.
Results
Data are still being tabulated,
but we can report the following
preliminary findings.
Demographic Information
With exception of gender,
neighbors and nonneighbors
were demographically similar.
The neighbors who completed
surveys were fairly evenly split
between males and females,
whereas nonneighbors who com
pleted surveys were predomi
nantly male.
Effectiveness Of
Odor Reduction
Technologies
Odor scores, in general, were
lower than anticipated on the
farms. On a scale of zero (no
odor) to five (very intense odor),
the mean odor score recorded by
respondents who returned odor
evaluation cards was .85.
For two of the three farms
where biofiltration was used, the
average odor score declined
after installation of the
biofilters, and, in one of these
cases, the decrease was statisti
cally significant (P less than
.05). In addition, although the
number of neighbors responding
to the farms on which floating
biofilters were used was very
small, the overall average
showed a decline in odor level
after the application of this
strategy.
Moreover, when standing
near the source, our personal ob
servation was that both biofilters
and the biocovers were effective
in reducing odor levels. As a
result, follow-up studies using
both of these technologies are
planned. The dust filtration
“socks” appeared to be ineffec
tive.
Physical And Personal
Factors Affecting
Odor Scores
The neighbors’ location (both
distance and direction from the
swine unit) impacted the inten
sity of reported odor. In general,
neighbors closer to the swine fa
cility recorded higher scores
than those more distant. Neigh
bors to the east and south
recorded higher scores than
those living to the west and
north. There were also numer
ous personal factors that af
fected perceived odor intensity,
including:
1. Whether the neighbor knew
the operation/manager of the
swine facility or not was related
to the reported odor level. In
general, the more the neighbor
was acquainted with the swine
producer, the lower the odor
scores.
2. Odor ratings were higher if
the neighbor could see the swine
facility from the road or home
than if they were not visible.
3. The more “attractive” the
farm was perceived to be, the
lower the odor scores. Attrac
tiveness of the farm in question
if the farm was perceived as
more attractive, lower odor
scores were recorded.
4. As reported health rating
increased, the lower were the
odor scores.
With the factors described
above, we could account for
about 33 percent of the variation
in average odor scores.
There were also a number of
personal factors that had little
or no impact on odor scores.
These included income, gender,
age, education, whether the
neighbor had been raised on a
farm, length of time the neigh
bor had lived there, and the
neighbor’s reported knowledge
of swine production.
Many neighbors commented
on their odor diary cards that
the intensity of odor during the
study was lower than normal be
cause the swine producer was
not spreading manure. We
asked all the cooperating pro
ducers to postpone manure
spreading until after the project
so that we could evaluate the
impact of the building and/or
storages alone. While the com
ments on manure spreading
were unexpected, they do rein
force the concept that land ap
plication of manure may
generate more odor complaints
than the buildings or manure
storage facilities.
Neighbor Vs.
Nonneighbor Perceptions
Neighbors and nonneighbors
were asked to “agree” or “disa
gree” with a series of 19 state
ments dealing with their
perceptions of large-scale live
stock operations. Of those who
responded, the answers of neigh
bors differed significantly from
those of nonneighbors for just
five of the items. Neighbors were
more likely than nonneighbors
to indicate that livestock odors
represent a health hazard to
people living nearby (47 percent
vs. 25 percent); to report that
odor from large-scale livestock
operations are more offensive
than other odors associated with
farming (59 percent vs. 40 per
cent); to disagree that large
scale livestock operations
provide the same economic ad
vantage to an area as other in
dustries (68 percent vs. 51
percent); to report that livestock
farmers should alter their farm
ing practices to satisfy the de
sires of nearby residents (74
percent vs. 60 percent); and to
believe that large-scale livestock
operations reduce the value of
nearby residential property (77
percent vs. 64 percent).
For the remaining 14 items,
neighbors and nonneighbors did
not differ significantly in their
pattern of responses. Thus, for
example, just over 60 percent of
both neighbors and nonneigh
bors agreed that large-scale live
stock operations use
environmentally sound practices
to prevent water pollution. Nev
ertheless, nearly the same per
centage reported that they
believed that animal wastes
from large-scale livestock opera
tions pollute nearby surface and
ground water (65 percent), pol
lute local water supplies (63 per
cent), and that governmental
controls and site inspections do
not eliminate the likelihood that
such operations will pollute
local water suppliers (61 per
cent).
Two-thirds (67 percent) be
lieved that large-scale livestock
always produce odors that are
obnoxious to people living
nearby and that people living in
the country should expect live
stock odors as part of country
living (78 percent). However, 64
percent reported that they did
not agree that livestock farmers
should have the right to farm
without local restriction, and 66
percent believed that large-scale
livestock operations should not
be permitted near residential
areas. More than three-fourths
of both neighbors and nonneigh
bors agreed that spreading
manure from large-scale live
stock operations on farmland
will enhance the quality of the
soil and only about one in five
believe that the application of
large amounts of manure from
intensive livestock operations
contaminate the soil, making it
useless for other agricultural
purposes. Thus, while there
were some striking differences
between neighbors and non
neighbors in the perception of
large-scale livestock operations,
there were also quite a number
of areas of agreement.
When respondents were
asked to rate their overall health
status, the scores of neighbors
and nonneighbors were identical
(4.1 on a scale of 1 not very
healthy to 5 very healthy). But
when asked about specific medi
cal symptoms, neighbors indi
cated they experienced cough,
nausea, fatigue, and throat irri
tation more often (P less than
.05) than nonneighbors. There
were no significant differences
between the two groups in
regard to frequency of head
aches, muscular aches, chest
tightness, depression, or anxiety.
The challenge aspect of these
observations is that the health
score and symptoms are self
rated and therefore may be sub
ject to some bias, particularly if
the neighbors regard the local
swine operation as a source of
conflict. To provide further
analysis of the health symptoms,
we calculated correlation coeffi
cients between distance from the
farm, and health score and all
health symptoms. For health
score and eight of the nine
symptoms, there was no signifi
cant relationship (P greater than
.20) between the frequency of
symptom and the distance from
the operation. One correlation
(muscular aches) approached
significance (P less than .075). If
the cause of the symptoms were
the facility, then one would
expect neighbors living close to
the farm would have observed
the symptoms more frequently
than those living further away,
but this was not the case.
To provide further insight
into the health symptom obser
vations, we calculated correla
tion coefficients between the
nighbors’ reported desire not to
live in this location, and the
same health symptoms. In this
analysis, the frequency of
nausea, headache, muscular
aches, chest tightness, fatigue,
throat irritation, depression and
anxiety were all positively corre
lated (P less than .01) with the
neighbors’ desire to live some
where else because of the swine
facility. Similarly, health score
was negatively correlated (P less
than .05). Therefore, it appears
that the neighbors’ health scores
and reported frequency of
health symptoms may be related
to dissatisfaction with their loca
tion, rather than to distance
from the swine operation.
A sizable majority of the
neighbors indicated that the
large-scale swine operation lo
cated nearby impacted on their
lifestyles in various ways. A
third (33 percent) reported that
they had often modified their
outdoor plans because of odor
from the facility, 18 percent had
often decided to not invite friend
in because of the odor, six per
cent thought that the odor from
the facility often made them ill,
and 22 percent reported that
they often wished that they
didn’t live in their current loca
tion because of the presence of
the swine facility. About 85 per-
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