Faculty of the Departments of Agricultural Engineering and Animal Sciences, College of ACES, who work closely with the issue of odor emissions in animal confinement operations believe that the odor problem can be solved to the point of enabling confinement production and communities to co-exist and flourish. Many resources throughout the industrialized world are targeted at solving various parts of the animal odor problem. University of Illinois scientists, representing the Departments of Agricultural Engineering, Food Science and Human Nutrition, Chemical Engineering, Civil Engineering, and the Illinois State Water Survey are collaborating with researchers at other institutions and are systematically exploring unique facets of the odor challenge, so that work at other institutions is not duplicated unnecessarily. Researchers at the University of Illinois College of ACES and affiliated colleges are using unique talents and specialized laboratory resources to contribute pieces to the odor control puzzle.
The major areas of animal production odor being studied at the University of Illinois are:
There are several odor production and transport stages between the source and the odor reaching a human nose. Significantly reducing or arresting the odor at any stage solves the odor problem for that production practice. To test odor-reducing technologies appropriately, University of Illinois scientists are working to develop the capability to sample airborne odorous compounds reliably and then accurately analyze them. Once the capability is developed, researchers can determine exactly whether a technology or practice change has made a difference in odor. The sampling and analysis protocols will be the basis upon which all other odor research will be evaluated.
Current state-of-the-art odor measurement at other institutions around the world relies on dilution olfactometers which employ trained human “sniffers” to quantify the intensity of odors in and around animal facilities. The olfactometry measurements are time-consuming, expensive, somewhat unreliable, and cannot analyze odors carried on dust. To conduct good odor research, scientists need an inexpensive and dependable odor measurement to complement olfactometry. University of Illinois faculty are striving to go beyond the capabilities of current odor measurement standards in order to have more objective, higher quality results.
Food scientists, agricultural engineers and animal scientists are using sophisticated analytical techniques and equipment to map the compounds in swine odor. Two of the tools employed to quantify the odor spectrum are the gas chromatograph (GC) and mass spectrophotometer (MS). The odor spectrum can be thought of as a fingerprint from a sample that allows scientists to identify unknown compounds. Once the GC/MS instruments produce the fingerprint, standard libraries of chemical responses can be searched to identify which chemical compounds are present in the odor. To determine how much of each identified compound is present, technicians compare the fingerprint with standard curves derived from known compound concentrations. The GC/MS tells the scientist what chemicals are present, and how much of each.
Along with the effort of analytical GC/MS measurement of odor, a simplified olfactometry method is being studied. A panel of trained sniffers will judge the offensiveness of odor samples collected on carefully treated cotton swatches.
Ultimately, this group of researchers will help evaluate changes in animal facility odor due to nutrition, facility management, and other odor control technologies.
The diets of animals largely determine the nature of the manure excreted. University of Illinois faculty in the Department of Animal Science are carefully studying interactions among dietary components in swine diets, and are investigating the effects of substituting various protein and carbohydrate sources for more conventional feedstuffs.
There is already a considerable volume of dietary research data showing the potential for reducing odor or changing the characteristics of odor produced during manure decomposition while it is stored. U of I animal scientists will be building on previous nutrition studies regarding protein digestibility. They will also look for relationships among bioactive, non-nutritive feed components such as antibiotics, minerals, acids, electrolytes, enzymes, and probiotics and their effects on odor. Researchers will also test the effects of feed production form (granular, pelleted, liquid) on odor production.
Odor evaluation during the nutrition research trials will be performed using the methods currently under development at the University.
Animal odors adhere to dust particles and can easily be carried long distances on dust, from which the odors are then released over time. Reducing dust in an animal confinement building can substantially cut odor levels downwind. The Department of Agricultural Engineering and the Illinois State Water Survey have world-class expertise in particle dispersion and transport phenomena and measurements. University researchers have already tested some ideas for reducing dust, and are developing the facilities needed for proving the ideas in both laboratory scale and full-scale experiments.
Dust from animal facilities is very different from other types of dust such as field dust. The dust:
Defining the characteristics of animal building dust is very important to the applied odor-control research. Quantifying the odor carried on different sizes of dust particles will allow scientists to optimize their strategies for removing the dust and odor. The size of a dust particle affects its behavior in the air and in the human respiratory system. The respirable particles (smaller than 10 microns in diameter, similar to tobacco smoke) are responsible for the health and odor problems because, for one thing, particles that size can travel deep into the lungs. Large particles (larger than 10 microns) usually bypass the nose or are trppaed in the respiratory tract and are naturally kept out of the lungs. Particles of all sizes may contribute to odor transport from the animal building.
This research project focuses on quantifying:
Recent results have already shown important distinctions between odor components carried by feed dust alone and the composite dust mixture that is found in swine buildings.
The study of airborne dust is complex. In order to characterize the dust properly, a sampling method is needed that will separate the dust without gaining or losing any odorous compounds that are adsorbed to the dust. A sampling train is being developed that consists of a denuder for gaseous compound capture, followed by filters for particulate capture and a final adsorbent trap for compounds that desorb from the captured particulates. One form of sampling to be developed is a dynamic sampling of the dust and gaseous phase from swine finishing buildings. The second form of sampling is to collect dust from swine finishing buildings using various sized filters to separate the dust into different particle sizes. All dust and gaseous phase samples will be desorbed and analyzed using GC/MS.
Finally, the dust spatial distribution willbe measured using a special multi-point sampler throughout a typical swine finishing room to characterize the spatial distribution. The multi-point sampler is designed to simultaneously take individual, yet identical, air samples from a number of different places in the room. This information will reveal the locations and sources of high dust concentrations, and therefore tell scientists where to place internal dust removal equipment for best effectiveness.
An axial-flow cyclone dust separator or “deduster” has been built and tested, and has proven its ability to capture a substantial fraction of the odor carrying dust particles. The deduster is similar to a large room air filter but it utilizes centrifugal force to separate and capture the dust particles instead of using porous filters that would tend to clog quickly in hog buildings. The deduster can be used in animal buildings that are naturally ventilated or mechanically ventilated, to reduce the amount of dust that would otherwise be exhausted from the buildings and possibly be detected downwind. Advantages of the deduster:
Tests of the prototype have shown that the prototype removes 85 percent of the particulates with very low energy requirements. However, this prototype has only been designed for, and tested at, one airflow rate. Engineers will need to develop designs for a wide range of airflow capacities to fit numerous applications for cleaning air within swine buildings. The first step is to standardize the design procedures of the deduster to accommodate various air delivery rates for different swine building applications. Second, gas phase odor removing technologies will be built into the deduster and evaluated. The technologies of interest include ozone treatment and an activated carbon fiber (ACF) filter, either of which is expected to further reduce the odor in the gaseous state after the dust removal, and also improve productivity and welfare of animals and workers.
A program has been developed for testing odor control technologies and practices in operating production facilities. The first year, this program will test some odor control methods that have a high probability of success; then other research results will be integrated into the program as they become available. The swine odor control proving program is needed because things that work in the laboratory do not always work as well in the real world. They may also have an effect on the animals or workers, or may interact with other odor control technologies. It is most likely that a single odor control method will not be sufficient to solve the problem, so two or more methods will have to operate at the same time. How well a number of odor control methods work together will need to be tested in operating swine production facilities.
One example of the proving center concept is the testing of oil sprinkling as a dust suppression method. A very light daily sprinkling of vegetable oil in the pens of pigs has been shown to decrease the dust up to 80% and odor levels up to 50%. The film of vegetable oil on surfaces apparently ties up the very small dust particles so that they are not dispersed into the air. The proving center program has already completed a replicated test of oil sprinkling in small production-scale facilities. The next phase of the oil-sprinkling project is to build and demonstrate an automated system for sprinkling the oil, to eliminate manual spraying.
Manufacturing industries and power generation plants use various kinds of “scrubbing” techniques to actively remove particles and/or gases from exhaust streams venting into the atmosphere. Although today’s scrubber technology is well developed and versatile for industrial uses, the commercial units are generally not cost effective for odor and dust control in animal production facilities. However, there may be some possible uses for a more simple, direct approach to scrubbing exhaust air from a fan.
A big challenge is to design a scrubber system that utilizes recycled process water and is affordable. If the water used to clean the air in a wet scrubber can be treated and recycled, it would help the acceptance of this technology. The cost of using fresh water and the storage of the process water may be prohibitive. The investigation of process water treatment will include a solids removal process followed by odorous compound removal with a wet biofilter, activated carbon, or ozone treatment. Readily available commercial equipment will be used, and evaluated for performance and cost-effectiveness.
Catalytic converters are commonly used on internal combustion engines to reduce odors and toxic emissions. The objective of this study is to adapt industrial converter technology to reduce the odors produced in swine facilities. Scientists in the University of Illinois Department of Chemical Engineering are developing a catalytic air cleaner to place in the ventilation system of an existing animal production facility to reduce odors. A second project is to explore catalytic “odor-eaters” that could be placed inside animal confinement facilities to absorb odor-causing compounds. The research is currently in the proof of concept stage, which, if shown successful, could be an inexpensive way to treat odors.
The thermochemical conversion (TCC) process is a chemical reforming reaction of organic compounds and water in a heated enclosure to produce oil and gas. Unlike pyrolysis, which requires the feed stock to be dry, the TCC process treats the wet feed stock directly. TCC technology has been studied using feed stocks such as coal and wood sludge since the oil crises in the 1970’s, but the research was discontinued because of low oil prices and high cost of feedstocks. The TCC process, however, can be applied to livestock manure — a zero-cost byproduct. A bench-scale thermochemical conversion (TCC) processor has been developed to study the conversion of swine manure to oil and gases.
The effects of the process parameters, including temperature, pressure, solids content, retention time, and pH, on the conversion of swine manure to oil and gases are being examined. So far, process parameters tested have been 180-275°C, 1.0-6.0 MPa, 20 percent total solids, 1.0 to 3.0 hours treatment time, and pH 6. The COD of the post-processed water was significantly reduced compared to the untreated slurry. Substantial heat was generated during the process. Preliminary data show that the TCC process is promising and could be an attractive technology to treat swine manure. Since TCC is a closed-loop process, odor and waste can be substantially reduced. The wastewater resulting from the process is much cleaner, and solid plant fertilizer is a byproduct.
A significant part of the total odor emitted from animal production facilities is from the manure storage. Existing odor control methods for manure lagoons are expensive and often not very effective. While floating types of manure storage covers have significant drawbacks, inflatable covers appear suited for small to moderately sized outdoor manure storages. An earlier study demonstrated that a balloon type of synthetic cover could be an economical and effective method to reduce odor emission to the atmosphere.
The plastic sheet was inflated using a low-pressure furnace blower, suspending the cover over the manure storage and virtually eliminating the odor emission. That cover has been in continuous operation since its installation in 1994, and has required no maintenance. The cover also improved the visual landscape of the farmstead. The cover supplier provided a 15-year warranty. Based on a 10-year service life, the cost for that cover was approximately 10 cents per square foot per year, or 8 cents per pig marketed. The suppliers are developing a low-cost inflatable lagoon cover for rectangular-shape earthen lagoons. The cover will be installed, demonstrated and evaluated on the primary earthen lagoon at the Moorman Swine Research Farm, UIUC.
Researchers expect this study to yield an economical and practical method for reducing odor from lagoons, preventing rainfall collection and manure spills. Nitrogen in the manure will also be preserved with the covered lagoon. Open top earthen lagoons lose about 80 percent of the nitrogen in the diluted manure during the storage. The cover will obscure the appearance of the lagoon, thus minimizing the perception of odor as well.
Odor from animal production facilities is a complex issue. Faculty at the University of Illinois are aggressively pursuing solutions to the odor problem, employing specialized facilities and expertise. There are near-term components to the solution, using technology and methods that are already known or are close to market. The longer-term components, encompassing radical technology and community/producer cooperation, are being studied concurrently so that the animal production industry in Illinois may remain viable and sustainable for the foreseeable future.
Substantial funding for Illinois livestock odor research has been provided through the Illinois Council on Food and Agricultural Research (C-FAR).