Public concerns regarding
livestock production in Iowa have influenced research and legislation.
In 1996-97, Iowa State University (ISU) evaluated the effectiveness of
odor control technologies on eighty livestock farms of varying size and
producing primarily swine. The technologies evaluated were synthetic covers, aeration,
biocovers, pit additives, soil injection, anaerobic digestion, composting and
landscaping. Odors were evaluated
by field staff using scentometers and by field day participant’s reports
during activities, especially land application.
In 2002, ISU received 562 responses to a swine survey to assess odor
complaints and technologies used on swine production facilities throughout the
state. Results from the
demonstration project and surveys indicated a wide range of costs and
effectiveness of different technologies and concluded that there is no one best
solution for odor reduction.
Although the state, in an
effort to maintain consistency, regulates Iowa’s livestock facilities, citizen
action groups have advocated for greater control at the county level.
Current state regulations are designed to protect water quality and
stipulate separation distances depending on the designated area, the number of
animal units (AU) and application type and rate.
New air quality rules, based on human health impacts, will limit hydrogen
sulfide and ammonia concentrations. To
allow some local control, the state is working to implement a master matrix to
approve new farms larger than 1,000 AU and expansion farms larger than 1,666 AU.
Each facility will be scored based on a number of parameters that affect
water and air quality and the total score will determine approval.
Both the state and county will have the right to appeal.
For more information about the
odor demonstration project results go to: http://www.extension.iastate.edu/airquality/pubs.html
Discussion:
Lingying Zhao (OSU) asked the
optimum size for using a biocover to reduce odor emissions and the thickness of
straw needed. Lorimor noted that
the biocover is effective only for earthen or concrete liquid slurry storage as
a lagoon has too large a surface area. The maximum size is 120 feet, although it may be possible to
increase that somewhat if windbreaks or twine or other restraint is used across
the top of the straw to hold it in place. A
layer of 8 –12 inches of straw is needed.
Harold Keener (OSU) asked if
there are recommendations for specific species such as a two-stage dairy lagoon.
Lorimor replied that controlling water in a dairy operation is effective
and aeration can significantly improve odor control in a lagoon but it is
expensive. For deep pit swine
manure storage, there are not many choices.
The floor may be sprinkled with oil to reduce the dust which is
associated with approximately 50% of the odor; however, it is not often used as
it makes the floor slippery. For
solid manure systems, frequent cleaning and composting are effective.
Lorimor suggested that most
odor complaints occur during land application.
The use of injection equipment to incorporate liquid manure can reduce
odors at that time.
Fred Michel (OSU) asked if
treating the exhaust air from a deep pit storage is effective.
Lorimor responded that biofilters can reduce odors but require that the
building be mechanically ventilated.
Keener asked about the
relationship between the state and federal EPA in regulating emissions.
Lorimor noted that at the federal level, the EPA is concerned with
identifying emission factors for specific species.
The state is more concerned with the concentration of emissions and the
potential health effect on the nearest downstream entity.
Keener cited a Minnesota study
of livestock facilities which indicated a high variance in emissions and asked
how such differences can be reconciled. Lorimor
suggested that the EPA will eventually set a limit in terms allowable emissions
per day and that the state will be responsible for enforcement.
At this time, the Iowa Department of Natural Resources has concerns about
the accuracy and quality control for measuring emissions.
Lynn Willett (OSU) asked about
the scentometers used during the odor demonstration project.
What is measured? What is the sensitivity?
Lorimor noted that there is little correlation between ammonia or sulfur
dioxide and odor. The scentometer
is used in as attempt to measure actual odor.
An adjustable carbon filter is used to control the detection threshold.
However, the instrument is not very accurate because the user has already
been exposed to the odor and is affected by visual cues.
An olfactometer, which uses bagged air that is mixed then assessed by an
odor panel in a sterile room, is more effective because there are fewer
variables.
Michel asked if the setback
distances make it difficult to achieve the concentrations for hydrogen sulfide
and ammonia as required by regulations. Lorimor
noted that the levels are low enough that there should be no problem if setbacks
are maintained. However, there is a
potential for exceeding the concentrations during application, especially if a
broadcast spreader is used. Also,
layer facilities may have more difficulty than swine facilities.
Notes
by Mary Wicks
The
OCAMM (Ohio Composting and Manure Management) Program is funded by OARDC/OSU.