A Workshop to Review BMPs and BATs for Control of Dust, Ammonia, and Airborne Pathogen Emissions at Commercial Poultry Facilities (Zhao)


Poultry production is a significant source of air pollutant emissions including particulate matter (PM), ammonia (NH3), and  pathogens, which negatively impact bird health and performance, human respiratory health, food safety, and local environmental quality. Effective and economically feasible management practices and technologies to mitigate air pollutant emissions and pathogen transmission are urgently needed.

In the past decade, a variety of management practices and control technologies have been developed and preliminarily tested in commercial poultry facilities, with varying degrees of success. Technologies that have been applied for PM control include air filtration, impaction curtains, oil/water spraying, wet scrubbers, electrostatic precipitation, and electrostatic spray scrubbing. Among these, electrostatic methods and wet scrubbing achieve high removal efficiencies for both fine and coarse PM. For NH3 gas mitigation, various forms of scrubbing technologies such as trickling biofilters, acid spray scrubbers, and electrolyzed water spraying have been tested in commercial poultry facilities, alongside management practices such as feed additives and litter amendments. Acid spray scrubbers can be particularly attractive to poultry facilities since the sulfuric acid from the scrubber reacts with NH3 to create ammonium sulfate, which can be used as fertilizer to offset scrubber operating costs. A new technology using artificial floor was recently studied and demonstrated significant reduction in ammonia and PM concentrations and emissions at laying hen housing.

The avian influenza outbreak in 2014/15 and the current spread of the Highly Pathogenic Avian Influenza (HPAI) remind us that pathogen control at poultry facilities is crucial. Technologies such as electrostatic precipitators, electrostatic spray scrubbers, and electrolyzed water spraying systems have been tested to assess their capacities for airborne bacteria reduction.

The technical and economic feasibilities of these methods need to be evaluated for proper consideration by poultry producers and their stakeholders. All the above research results need to be introduced to producers for practical applications.

What Did We Do?

This workshop is organized for the researchers and Extension specialists to review the latest BMPs and BATs on control of dust, ammonia, and pathogens at poultry facilities for improved biosecurity, food safety, environmental quality, and the overall sustainability of poultry production.  We have developed the following presentations and will present them at 2022 W2W.

    1. Manure Drying Methods to Control Ammonia Emissions (Dr. Albert Heber-Professor Emeritus, Purdue University)
    2. A Spray Wet Scrubber for Recovery of Ammonia Emissions from Poultry Facilities (Dr. Lingying Zhao, Professor, Ohio State University)
    3. Electrostatic Precipitation Technologies for Dust and Pathogen Control at Poultry Layer Facilities (Dr. Lingying Zhao, Professor, The Ohio State University)
    4. Field Experiences of Large-Scale PM Mitigation (Dr. Teng Lim, Professor, University of Missouri)
    5. Mitigation of Ammonia and Particulate Matter at Cage-free Layer Housing with New Floor Substrate (Dr. Ji-Qin Ni, Professor, Purdue University)

What Have We Learned?

    1. Newly developed BMPs and BATs can improve air quality in commercial poultry facilities: Manure belt layer houses reduce ammonia emissions by removing manure from the layer houses in 1 to 7 days. Belt aeration using blower tubes is one method that has been used to dry the manure on the belt.  Drying tunnels take manure from layer houses and utilize ventilation exhaust air to further dry the manure before it enters the manure storage or compost facilities or transfers to pelletizing operations.  Manure sheds and compost facilities are ventilated with building exhaust air or fresh air to dry manure in storage.
    2. The use of acid spray scrubbing is promising, as it simultaneously mitigates and recovers ammonia emission for fertilizer. Its low contribution of backpressure on propellor fans makes it applicable on US farms. A full-scale acid spray scrubber was developed to recover ammonia emissions from commercial poultry facilities and produce nitrogen fertilizer. The scrubber performance and economic feasibility were evaluated at a commercial poultry manure composting facility that released ammonia from exhaust fans with concentrations of 66–278 ppmv and total emission rate of 96,143 kg yr−1. The scrubber achieved high NH3 removal efficiencies (71–81%) and low pressure drop (<25 Pa). Estimated water and acid losses are 0.9 and 0.04 ml m−3 air treated, respectively. Power consumption rate was between 90 and 108 kWh d−1. The scrubber effluents containing 22–36% (m/v) ammonium sulphate are comparable to commercial-grade nitrogen fertilizer. Preliminary economic analysis indicated that a break-even of one year is achievable. This study demonstrates that acid spray scrubbers can economically and effectively recover NH3 from animal facilities for fertilizer.
    3. Two types of electrostatic precipitation-based dust control technologies have been developed at the Ohio State University: the electrostatic precipitator (ESP) and the electrostatic spray scrubber (ESS). Field tests of the ESP and ESS conducted at a commercial layer facility indicated that (1) the fully optimized ESP achieved respective mean PM5, PM10, and TSP removal efficiencies of 93.6% ±5.0%, 94.0% ±5.0%, and 94.7% ±4.4% and (2) the ESS exhibited respective mean PM2.5, PM10, and TSP removal efficiencies of 90.5% ±10.0%, 91.9% ±8.2%, and 92.9% ±6.9%.  A system of 88 large ESP units to treat exhaust air from the 4-house poultry facility at the minimum required ventilation rate of 24.8 m3 s-1 would have an initial cost of $757,680 and an annual operating cost of $10,831 ($13.43 per 1,000 birds), increasing annual facility electricity consumption by 54.2%. A system of ESS units designed to treat exhaust air for six exhaust fans in each of the 4 poultry houses that operated continuously year-round for minimum ventilation, is estimated to have an initial cost of $71,280 with an annual operating cost of $21,663 for water consumption and electricity usage. The ESP is more effective, and the ESS is more economically feasible to mitigate PM at a commercial egg production facility.
    4. The field-scale measurements of PM mitigation technologies are usually time-consuming to set up and maintain, and often only limited replications can be obtained. It is important to minimize interference to the routine farm operation. The use of different PM measurements, setup and maintenance required to ensure data quality, and differences between the mitigation technologies are discussed. It is important to consider practicality of the mitigations, along with safety, and long-term use of the different technologies.
    5. A new mitigation approach, using AstroTurf ® as floor substrate, reduced indoor concentrations and emissions of ammonia and PM at cage-free aviary-style layer rooms in a recent study. Results demonstrated that the average daily mean ammonia concentration in the two AstroTurf® floor rooms (7.5 ppm) was significantly lower (p < 0.05) compared with that in the two wood shaving floor rooms (15.2 ppm) with a reduction rate of 51%. Average daily mean large particles (all particles detected above ~2.5 µm) and small particles (all particles detected below ~0.5 µm) in the two AstroTurf® floor rooms were significantly reduced (p < 0.05) by 70% (501,300 vs. 1,679,700 per ft3) and 63% (906,300 vs. 2,481,100 per ft3), respectively, compared with those in the two wood shaving floor rooms. With the controlled and consistent ventilation rates among the rooms in the study, the emissions of ammonia and PM (large and small particles) from the two AstroTurf® floor rooms had similar reduction rates.

Future Plans

More workshops to review BMPs and BATs for mitigation of air emissions and pathogen transmission in poultry facilities will be organized as new research development and findings emerge.  The workshop will target audiences of researchers, farmers, and professionals working with farmers.


Presenting authors

Lingying Zhao, Professor and Extension Specialist, The Ohio State University

Albert Heber, Professor Emeritus, Purdue University

Teng Lim, Professor, University of Missouri

Ji-Qin Ni, Professor, Purdue University

Corresponding author

Lingying Zhao, Professor and Extension Specialist, The Ohio State University

Corresponding author email address


Additional authors

Matt Herkins, Graduate Research Associate, The Ohio State University

Albert Heber, Professor Emeritus, Purdue University

Teng Lim, Professor, University of Missouri

Ji-Qin Ni, Professor, Purdue University

Additional Information


Hadlocon, L. J., A. Soboyejo, L. Y. Zhao, and H. Zhu. 2015. Statistical modeling of ammonia absorption efficiency of an acid spray scrubber using regression analysis. Biosystems Engineering 132: 88-95.

Hadlocon, L. S., R.B. Manuzon, and L. Y. Zhao. 2015. Development and evaluation of a full-scale spray scrubber for ammonia recovery and production of nitrogen fertilizer at poultry facilities. Environmental Technology 36(4): 405-416.

Hadlocon, L.J. and L.Y. Zhao. 2015. Production of ammonium sulfate fertilizer using acid spray wet scrubbers. Agricultural Engineering International: CIGR Journal. 17 (Special Issue: 18th World Congress of CIGR): 41-51.

Hadlocon, L.J., L.Y. Zhao, B. Wyslouzil, and H. Zhu. 2015. Semi-mechanistic modeling of ammonia absorption in acid spray scrubbers based on mass balances.  Biosystems Engineering 136:14-24.

Heber, A. J., T.-T. Lim, J.-Q. Ni, P. C. Tao, A.M. Schmidt, J. A. Koziel, S. J. Hoff, L.D. Jacobson, Y.H. Zhang, and G.B. Baughman. 2006. Quality-assured measurements of animal building emissions: Particulate matter concentrations. Journal of the Air & Waste Management Association. 56(12): 1642-1648.

Knight, R. M. L.Y. Zhao, and H. Zhu. 2021. Modelling and optimisation of a wire-plate ESP for mitigation of poultry PM emission using COMSOL. Biosystems Engineering 211: 35-49.

Knight, R., X. Tong, L. Zhao, R. B. Manuzon, M. J. Darr, A. J. Heber, and J. Q. Ni. 2021. Particulate matter concentrations and emission rates at two retrofitted manure-belt layer houses. Transactions of the ASABE 64(3): 829-841. (doi: 10.13031/trans.14337)

Knight, R., X. Tong, Z. Liu, S. Hong, and L.Y. Zhao. 2019. Spatial and seasonal variations of PM concentration and size distribution in manure-belt poultry layer houses. Transactions of the ASABE 62(2):415-427. doi: 10.13031/trans.12950

Lim, T. T., H. W. Sun, J.-Q. Ni, L. Zhao, C. A. Diehl, A. J. Heber, and P.-C. Tao. 2007. Field tests of a particulate impaction curtain on emissions from a high-rise layer barn. Transactions of the ASABE 50(5): 1795-1805.

Lim, T.-T., Y. Jin, Ni, J.-Q., and A. J. Heber. 2012. Field evaluation of biofilters in reducing aerial pollutant emissions from commercial finishing barn. Biosytems Engineering 112(3): 192-201.

Lim, T.-T., C. Wang, A. J. Heber, J.-Q. Ni, and L. Zhao. 2018. Effect of electrostatic precipitation on particulate matter emissions from a high-rise layer house. In Air Quality and Livestock Farming, 372 p. T. Banhazi, A. Aland, and J. Hartung, eds. Australia: CRC Press, Taylor and Francis Group.

Ni, J.-Q., A.J. Heber, M. J. Darr, T.-T. Lim, Diehl, and B. W. Bogan. 2009. Air quality monitoring and on-site computer system for livestock and poultry environment studies. Transactions of the ASABE 52(3): 937-947.

Ni, J.-Q., A. J. Heber, E. L. Cortus, T.-T. Lim, B. W. Bogan, R. H. Grant, and M. T. Boehm. 2012. Assessment of ammonia emissions from swine facilities in the U.S. – Application of knowledge from experimental research. Environmental Science & Policy 22(0): 25-35.

Ni, J.-Q., L. Chai, L. Chen, B. W. Bogan, K. Wang, E. L. Cortus, A. J. Heber, T.-T. Lim, and C. A. Diehl. 2012. Characteristics of ammonia, hydrogen sulfide, carbon dioxide, and particulate matter concentrations in high-rise and manure-belt layer hen houses. Atmospheric Environment 57(0): 165-174.

Ni, J.-Q., S. Liu, C. A. Diehl, T.-T. Lim, B. W. Bogan, L. Chen, L. Chai, K. Wang, and A. J. Heber. 2017. Emission factors and characteristics of ammonia, hydrogen sulfide, carbon dioxide, and particulate matter at two high-rise layer hen houses. Atmospheric Environment 154: 260-273. http://dx.doi.org/10.1016/j.atmosenv.2017.01.050.

Tong, X., L.Y. Zhao, A. Heber, and J. Ni. 2020.  Mechanistic modelling of ammonia emission from laying hen manure at laboratory scale. Biosystems Engineering. 192:24-41.

Tong, X., L.Y. Zhao, A. Heber, and J. Ni. 2020. Development of a farm-scale, quasi-mechanistic model to estimate ammonia emissions from commercial manure-belt layer houses. Biosystems Engineering 196, 67-87.

Tong, X., L.Y. Zhao, R. B. Manuzon, M. J. Darr, R. M. Knight, C. Wang, A. J. Heber, and J.Q. Ni. 2021. Ammonia concentrations and emissions at two commercial manure-belt layer housed with mixed tunnel and cross ventilation. Transactions of the ASABE 64(6): 2073-2087. (doi: 10.13031/trans.14634)

Tong, X., S. S. Hong., and L.Y. Zhao 2019. Development of upward airflow displacement ventilation system of manure-belt layer houses for improved indoor environment using CFD simulation. Biosystems Engineering 178:294-308.

Zhao, L.Y., L. J. S. Hadlocon, R. B. Manuzon, M.J. Darr, H. M. Keener, A. J. Heber, and J.Q. Ni. 2016. Ammonia concentrations and emission rates at a commercial manure composting facility. Biosystems Engineering  150: 69-78.


The wet scrubber development was supported by National Research Initiative Competitive Grant 2008-55112-1876 from the USDA Cooperative State Research, Education, and Extension Service Air Quality Program. The ammonia emission modelling work was supported by the USDA-NIFA Grant 2018-67019-27803.

The electrostatic precipitation-based dust control work was supported by the USDA National Institute of Food and Agriculture Grant 2016-67021-24434.

The Project funding for the Mitigation of Ammonia and Particulate Matter at Cage-free Layer Housing with New Floor Substrate presentation was provided by the U.S. Poultry & Egg Association. GrassWorx LLC provided the AstroTurf and financed the building of the flooring systems.

Appreciation is also expressed to the U.S. EPA, and participating producers and staff for their collaboration and support.


The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

Benefits of Bedding Reuse for the Equine Industry

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Why Studying Bedding Reuse for Horses?

To examine the financial, operational and health benefits of re-using composted bedding in the equine industry.

What Did We Do?

Stable waste, consisting of manure, urine and wood shavings, is a readily compostable feedstock that generates heat and can be transformed into finished homogenous compost, which can be used as bedding for horses and other livestock.  This transformation can be completed in as little as 2 weeks with in-vessel technologies, 15-25 days in aerated site-built systems and 20-30 days in aerated static pile (ASP) systems.  If composting is done in a biologically active, aerobic environment such as the systems mentioned above, the process destroys weed seed, parasites and harmful pathogens. These benefits are the result of system controls such as a correct ratio of C:N, moisture, porosity of the pile, and temperature.  The in-vessel composting system offers the most comprehensive control of these factors ensuring the most favorable results. 

The biological process that occurs when the stable waste is blended utilizes the leachable N and binds it in the organic matrix keeping it secured.  There is also a reduction in N during the process as it becomes volatile and escapes through vaporization.  The phosphorus is utilized by the bacteria during the process, reducing the amount available to leach by at least 50%.   Since both N and Ph are needed for cellular growth, they get locked in the cells of the growing bacteria.  This process generates heat, removing the moisture, killing pathogens and creating drier and more absorbent material for bedding re-use.

IOS Ranch, a private 20 horse show stable on Bainbridge Island, Washington, was the study site for this paper.  They purchased an Earth Flow in vessel system and it is from this system that the lab results and observational data were collected.  Their bedding of choice is medium sized bulk shavings.  Also studied over the same period of time was the Earth Flow in-vessel system at Joint Base Myers/Henderson in Arlington, Virginia.  The US Army Caisson horses stabled there are bedded on pelletized bedding.  Lab data from this composting mix contributed to this study as well.

Washington State University, encouraged by the potential of financial savings, started using composted material as bedding in the school’s dairy farm.  An unexpected benefit of this decision was the reduction of mastitis in the dairy herd.  The change in bedding was the only variable altered in the care of the herd when this observation was noted.  A study conducted by Cornell University’s Waste Management Institute studied the financial effects of using manure solids (DMS) as bedding.  This study showed an average of $37,000 was saved annually by the diary farms who switched to re-use bedding.  It was from these observations that we decided to apply the same questions to the equine industry. 

A study conducted by Caitlin Price Youngquist of the Snohomish Conservation District, and funded by Western SARE is searching for the health benefits to horses with the use of composted stable waste as bedding. Preliminary examination has shown an increase in foot and leg health and a decrease in thrush, scratches and dermatitis seen on the horses in the study.  General foot and leg health was also attributed to compost bedding by Dr. Hannah Mueller of Cedarbrook Veterinary Clinic and Northwest Equine Stewardship Center.  She documented relief for a horse with chronic hives and a horse with a tracheotomy.   The reduction of dust has been cited as a benefit to the horses suffering from heaves and other dust related ailments such as skin and respiratory irritations.  The compost material has the  unique quality of a large capacity for absorption while at an already higher level of moisture that makes the compost bedding less dusty. Both pellets and shavings exhibit this attribute.Youngquist’s assumption for the benefit composted bedding offers is based in the process itself.  She states, “The compost has been through a very hot phase to kill all pathogens and parasites. It now has a thriving microbial population that competes aggressively with the fungal and bacterial pathogens that cause infections and irritations on skin and hooves (similar to the concept of a pro-biotic).”

Stable waste compost as bedding can be used in its entirety or screened to collect the larger remaining pieces of shavings for bedding, leaving the fines for soil amendment. Testing has shown in either case the composted material to have high absorbency, more so than green shavings.  When mixed with 50% new or green shavings, the stall is at its most efficient for health and comfort for the horse.  The composted material offers higher absorption, soaking up the urine off the stall floor.  With a top dressing of new shavings the stall is aesthetically pleasing to the human eye, light in color and offering the horse a barrier to the wetter, compost material below.  The compost bedding is odor free when reintroduced to the stall.   The introduction of at least 50% new shavings also supports the ongoing composting system, refilling the system when it has its 40-50% reduction of volume and the eventual breakdown of the shaving pieces with multiple trips through the system.    Continuing research is being done to understand the effect of pelletized bedding used in the bedding re-use loop without the introduction of a larger substance to affect the integrity of the material as it continues to be re –used.

The first test done was to measure the absorption ability of the three types of bedding mixes.  Two inches of material was placed in a plastic container.  The first test done on 2” of green shavings, the second test done on 2” of a 50/50 mix of green shavings and compost, and the third test done on 2” of compost.  Each of the variations was weighed before the introduction of water.  One gallon of water was poured over the material and allowed to stand for 2 minutes.  The container was then drained of any standing water which was measured.  The container was again weighed in each case after the water had been drained.  This procedure allowed for the measurement of absorption by both the increase in weight and the volume of water not absorbed by the material.

The new shavings taken from a loose pile absorbed the least, the 50/50 mix the next higher amount and the compost bedding absorbed the most moisture.  This is impressive when one considers that the density of compost bedding is higher before the introduction of the test water.  The compost material is comprised of the same woody fiber as the shavings but the edges have softened and loosened, and it is possible that the breakdown of the resins, which can be hydro phobic, allows for additional absorption ability.

We also tested for the moisture content of each bedding type with a simple oven test.  The material was measured by a two cup measuring cup and poured into a glass baking dish.  The material was weighed before going into the oven, set at 200°.  The material was then weighed again to determine the moisture content after 12 hours.

These preliminary tests were performed to study initial benefits noted with bedding re-use.  These are not scientific studies and are only intended to show possible indications for the purpose of this paper and to encourage further study.  With composting and bedding re-use, barns close the waste stream loop and create a value added product.

What Have We Learned?

The viability of composted stable waste to be re-used as bedding is proven to provide financial benefits by saving  on the cost of material purchase and in the disposal of stable waste.  It provides  further savings in health care costs.

Laboratory Results for Composted Stable Waste

Laboratory Results for Composted Stable Waste

Laboratory Results for Composted Stable Waste

Future Plans

We will continue to support the Snohomish Conservation District study run by Caitlin Youngquist by supplying composted stable waste and collaboration. 

We plan to run our dust measurement during the summer months when we actually have dust in the Pacific Northwest. A furnace filter attached to the intake side of an 18” x 18” fan would be left on at ground level in a newly bedded stall for three minutes while the horse was hand walked around the stall.  This would be repeated for the three bedding variations.  The filter would be weighed before being attached to the fan and again after the three minute period.   

Study of pellets as bedding re-use material will be done, measuring the health benefits and the viability of the product over multiple uses.

A controlled trial on direct contact allergens will be conducted on the three bedding mixtures.

We will continue to educate the equine industry and encourage a broad scale adoption of this closed waste system.


Mollie Bogardus, MBA Sustainable Business, Equine Specialist, Green Mountain Technologies, Inc. and Michael Bryon Brown, President, Green Mountain Technologies, Inc.

Mollie Bogardus, mollie@compostingtechnology.com, Michael Bryon Brown, mbb@compostingtechnology.com

Additional Information

Bogardus, Mollie. “Equine Applications/Case Studies/ IOS  Ranch and Fort Myer/Henderson.” Green Mountain Technologies. Green Mountain Technolgies, Inc., n.d. Web. 15 Mar. 2013. http://compostingtechnology.com/equine/.

Cohen, Jamie. “Composted Horse Manure:  The Pros and Cons.” The Florida Horse Feb. 2013: 23. Print.

“Equine Applications.” Green Mountain Technologies- lab results. N.p., 12 Dec. 2012. Web. 1 Mar. 2013. http://compostingtechnology.com/equine.

LeaMaster, Brad, James R.  Hollyer, and Jennifer L. Sullivan. “Composted Animal Manures: Precautions and Processing.”   Cooperative Extension Service,College of Tropical Agriculture and Human Resources, University of Hawai‘i. University of Hawaii at Manoa, n.d. Web. 6 Mar. 2013. http://www.ctahr.hawaii.edu/oc/freepubs.

Price Youngquist, Caitlin. “Composted Horse Manure and Stall Bedding Pilot Project – YouTube.” YouTube. Snohomish Conservation District, 17 Jan. 2013. Web. 1 Mar. 2013. https://youtu.be/B91U5UjuaXI.

Schwartz, Mary, Jean Bonhotal, and A. Edward Stachr. “Use of Dried Manure Solids as Bedding for Dairy Cows.” Cornell Waste Management Institute. Cornell University, n.d. Web. 1 Oct. 2012. http://cwmi.css.cornell.edu>.

Wheeler, Eileen , and Jennifer Smith Zajaczkowski. “Horse Stable Manure Management.” Cornell Cooperative Extension, Orange County Equine, Saratoga County Equine. Penn State University, n.d. Web. 6 Mar. 2013. http://cceequine.org.

Zaborski, Ed. “Composting to Reduce Weed Seeds and Plant Pathogens – eXtension.” eXtension – Objective. Research-based. Credible.. University of Illinois at Urbana Champaign, 22 Oct. 2012. Web. 2 Oct. 2012. http://www.extension.org/pages/28585/composting-to-reduce-weed-seeds-and….


This report could not have been done without the support of Philippe Le Dorze at IOS Ranch.  His interest and pursuit of knowledge pushed us to continue to search for improvements and greater knowledge.

The staff at Joint Base Myer/Henderson, Amy Fagan especially, were also willing participants in the pursuit of the perfect compost recipe.  Paul Brezovec at Concurrent Technologies Corp was a tremendous support to the project and continues to encourage the use of Earth Flow vessels for other bases.

A special thanks to Caitlin Price Youngquist for her ongoing dedication, collaboration and interest in the phenomena of bedding re-use.


The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.