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Most read articles
|0307 ANM: Preparing an odor management plan|
|Archives - Past Articles|
|Tuesday, 06 March 2007 09:15|
Manure management plans have become a standard practice for most animal production systems. These plans document the proper handling and application of manure onto cropland. Likewise, odor management plans systematically identify potential odor sources, determine control strategies to reduce these odors and establish criteria for implementing these strategies.
The development of an odor management plan consists of the following four steps:
1. Create a list of the potential odor sources on the farm.
2. Determine which of the odor sources are the most likely to bring about odor complaints.
3. List one or two odor control strategies for each of the significant odor sources.
4. Develop a protocol to respond to odor complaints.
Inventory of odor sources
Nuisance odors can be the result of a single odor source, a single odor event or the combination of several sources and events. Therefore, it is important to conduct a thorough inventory of all odor sources on the farm. This inventory should be conducted on-site in a systematic way to ensure that all odor sources are included.
Odors from an animal production site originate from three primary sources:
•manure storage structures
•animal housing (including open lots)
•land application of manure
However, other sources such as dead animal disposal sites, silage piles, feed centers and any other areas where organic matter is present may also contribute to odor emissions. These other odor sources are often overlooked in discussions about nuisance complaints. For instance, improperly managed dead animal disposal sites can generate significant amounts of odors.
Intermittent odor events (e.g., manure agitation) should also be listed in the odor inventory because often these events, though infrequent, can be the source of significant odor emissions and thus generate odor complaints.
A brief description of each odor source should be included in the inventory. This description should include the size of the odor source (physical area) and its distance and direction from roadways, neighbors, property boundaries, etc.
Descriptions of odor sources should include the following types of information:
•size or dimensions
•number and size of animals
•distance to neighbors and public areas
•distance to property line
•manure system (liquid, slurry, solid)
•type of storage
•type and number of animals contributing
•land application of manure
•type of application equipment (broadcast, knife inject, sweep inject, etc.)
•timing of manure applications
•location of manure applications
Determination of high odor sources
A good odor management plan must also identify which of the many on-farm odor sources have the highest potential to create nuisance odors. Research has shown that some odor sources emit more odor per unit area than other sources. Therefore, both relative odor emissions and the size of the odor source must be considered in determining the high odor sources. Intermittent sources, such as liquid manure agitation and pumping or land application, also cause relatively high odor emissions and should be considered in the development of a list of high odor sources.
Another factor to consider in determining high odor sources is the proximity of the sources to public areas or neighbors. Dilution of odors is caused through the mixing of odors with ambient air. This dilution of odorous air is a function of distance, topography and meteorological conditions. Farther distances between odor sources and the public will result in fewer nuisance complaints.
Topographical features can either enhance dilution or reduce dilution depending on the particular feature. Windbreaks or tree lines will encourage mixing of the odorous air with clean air, whereas valleys or low areas may reduce odor dilution.
Meteorological conditions also affect dilution. Maximum dilution occurs when the cool air near the ground is heating and rising. Conversely, during the late evenings when it is calm and the atmosphere is cooling, the odorous air is trapped near the ground and there is little dilution. Of these three factors (distance, topography and meteorology), separation distance will likely have the biggest impact on nuisance complaints.
Possible odor control technologies
Odor control technologies can be thought of in three different categories:
•those that reduce the generation of odors
•those that decrease the emission of odors
•those that increase dilution of odors
Several of these technologies are listed in Table 1*. Since there is little known about many of these technologies, the odor management plan should list one, two or possibly three control technologies for each of the high odor sources. If the first odor control strategy proves ineffective, then the second or third strategy can be implemented.
Reduce odor generation
Control technologies that reduce the production or generation of odorous gases include:
•manure treatment technologies such as anaerobic digesters or aeration systems
•diet manipulation to reduce the amount of manure produced or the amount of nutrients in the manure
•chemical or biological additives
Manure treatment technologies can be very effective at odor control but are typically expensive. Chemical additions can also be effective, and the cost depends on the specific chemical and the frequency of addition. Biological additives are typically less expensive than manure treatment or chemical additives, but their effectiveness often varies by farm site and particular additive.
Reduce odor emissions
Technologies considered to reduce emissions are those that capture and treat the odorous gases before they leave the site. In most situations, these gases are converted through biological, physical or chemical processes to other non-odorous gases. Biofilters are a good example of a technology that reduces odor emissions. A biofilter treats the odorous gases as they are emitted from an odor source. Microorganisms in the biofilter media oxidize these complex odorous chemicals into simple odorless compounds. The air emitted from the biofilter is nearly odor free.
Increase odor dispersion
Technologies that disperse and dilute odors include shelterbelts, windbreak walls and setback distances. Of these, setback distances are the most effective. New information on shelterbelts suggests some odor reduction occurs because of the increased turbulence caused by the windbreak and because of some capturing of the odorous gases on the tree foliage.
New or proposed facilities should be designed to minimize odor emissions. Currently, there are no standard criteria for odor reducing designs. However, any facility designed to reduce the surface area of manure exposed, control dust, capture and treat gaseous emissions, increase dilution of emissions or treat manure could be considered as a design to reduce odor emissions. This may be as simple as building a deep pit manure storage versus having an outdoor manure storage structure, using a pull plug system with manure stored in an outside covered storage structure or using a wet/dry feeder system to reduce dust.
A new or proposed facility might also include plans for future odor control technologies should an odor problem ever arise. The design might include a designated space for a biofilter, liquid solid separation equipment or plans for a windbreak. Solid manure systems also produce less odor per unit area than liquid systems and should also be noted on the odor management plan. Many new ideas and technologies are being developed to control odor. Those that prove successful should be integrated in future livestock facility designs.
Odor complaint response
One of the most important pieces of an odor management plan is the response protocol to address odor complaints. This is a critical issue from three perspectives. First, it is sometimes difficult to separate serious odor complaints resulting from excessive odor emissions from odor complaints registered by disgruntled neighbors during nonodor events. Second, it is difficult to determine how many valid complaints are needed to trigger the implementation of an odor control technology. And third, there must be some method for monitoring the effectiveness of the technology.
The complaint response protocol will set up an odor monitoring plan and set guidelines for an acceptable number of odor events and some method to evaluate the effectiveness of an odor control technology. For this, it is critical to foster and maintain a good relationship with neighbors and other community members.
Item 1. Avoid odor complaints
Avoid odor complaints by making an effort to control odor emissions, including peak odor events such as manure agitation or land application of manure. These efforts and their perceived effect on odors should be documented.
Item 2. Establish a relationship with neighbors and community members
An effective complaint response protocol requires the input of neighbors and other community members such as environmental service specialists, county feedlot officers and county and township officials. These individuals provide an honest evaluation of farm odor impacts. They could be listed on the odor management plan and help in the development of the complaint response protocol. A team approach fosters communication and flow of information which is critical to responding to complaints.
Item 3. Monitor odor events
Monitoring odor events will help verify odor complaints and identify odor sources. Monitoring might include scheduled drives around the farm perimeter with a notebook recording the date, time and location of the monitoring and the strength of any odors that were detected. Other monitoring might include record-keeping of odor events by neighbors or community members. Strength of odors can be recorded on a three point odor intensity scale where 1=detectable odors, 2=recognizable odors and 3=very distinct and annoying odors.
Item 4. Set acceptable intensity and frequency standards
Since odors are a part of all livestock and poultry farming enterprises, it is impossible to expect 100 percent odor free air around the farm. However, frequent odor events of high intensity are unacceptable. Therefore, some reasonable frequency of odor events should be established. This frequency could include a given number of odor events per month or per year that are acceptable. Above this frequency, the odor management plan would be implemented. Establishing the acceptable frequency and intensity (how often and how strong) of odor events should be done with input from neighbors and community members so everyone is familiar with the goals of the farm.
Item 5. Evaluate the odor control technology
After an odor control technology has been implemented, an honest evaluation of its effectiveness is needed. A complaint response protocol will outline evaluation methods and techniques. This evaluation will most likely be similar to Item 3.
Maintaining odor management plans
The odor management plan should be reviewed and adjusted as needed on an annual basis. Changes in farm operation and management, additions or modifications of buildings or manure storages, changes in ownership of surrounding property or changes in local, state or federal regulations may all be reasons for altering the odor management plan. The success of any farm operation can be measured by the avoidance of community conflicts and nuisance complaints. This requires a planned approach to odor management and good communication between the farm management and the community. ANM
Table omitted but is available upon request to