Reducing H2S, NH3, PM, & Odor Emissions from Deep-pit Pig Finishing Facilities by Managing Pit Ventilation

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Swine (maybe Dairy and Poultry)
Use Area: Animal Housing
Technology Category: Management
Air Mitigated Pollutants: Odor, Hydrogen Sulfide, Ammonia, Particulates (PM10)

System Summary

A recent study determined that a large majority (75 to 80 %) of the total NH3 and H2S emissions from a 2000-head tunnel-ventilated deep-pit pig-finishing barn for 45 days during August and September 2004 were emitted from the pit exhaust stream even though only 20 to 30 % of the total barn’s ventilation air was being provided by pit fans. This information allows producers with deep-pit facilities to strategically utilize catch and treat emission control technologies, such as biofilters, ONLY on pit fans airstreams that would result in large reductions (>50%) in the emissions of hazardous gases, odor, and particulate matter by treating only a small portion of the total ventilation air (figure 1). Another follow up study found that emissions of certain pollutants, may be reduced slightly (10 to 20%) by simply eliminating pit fans altogether for a deep-pitted pig building.

The phenomenal of a majority of the barn’s airborne pollutants being emitted by pit fans, may also be true for other swine production phases or for even other species (dairy and poultry) housed in deep pit facilities. This would mean that emission reductions of >50 % for certain pollutants are potentially possible when emission control technologies like biofilters are strategically placed on large emitting pit fan sources in deep-pit buildings. If only small reductions (<20%) of certain pollutants are needed, this maybe accomplished by the elimination of pit fans altogether.

Applicability and Mitigating Mechanism

  • Pit Fan(s) airstreams contain a majority of the critical airborne pollutants (NH3, H2S, PM10, odor) from deep-pitted pig buildings
  • If biofilters are strategically used on pit exhaust air, sizable (>50%) emission reductions of some pollutants are possible for either existing or new deep-pit facilities


  • Information only available presently for deep-pit pig finishing barns but anticipated similar results for other swine plus dairy and poultry housed in deep-pit buildings
  • Valid for NH3, H2S, odor, and certain PM fractions, not known if greenhouse gases will also be concentrated in the pit fan exhaust air of deep-pit facilities


There is no additional cost of this “technology” since a well-designed and operating ventilation system is required in any animal facility and especially in a deep-pitted pig building. There actually may be a cost saving if producers decided to install no or only a limited number of pit fans instead of the standard number for the livestock industry which is approximately 20% of the total barn’s ventilation system. A cost savings is often realized since the installation of pit fans is typically more expensive than wall fans plus pit fans have higher maintenance requirements and are more frequently in need of replacement.


Larry D. Jacobson1, Brian P. Hetchler1,David R. Schmidt11Bioproducts & Biosystems Engineering, University of Minnesota
Point of Contact:
Larry D. Jacobson,

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

Diet Modification to Reduce Odors, Gas Emissions and Nutrient Excretions from Swine Operations

Can Changing Pig Diets Reduce Odor Emissions?

The pork industry has undergone a rapid change in the past two decades, with a decrease in farm numbers and an increase in farm size. These changes magnify the stress of the compatibility of pork production with neighbors in rural America. Concerns of the potential impact of the swine operation on water and air quality and health are also raised due to numerous compounds often produced from anaerobic degradation of animal manures, such as, sulfurous compounds, volatile fatty acids (VFAs), and ammonia (NH3). Since the pig is the point source of excreted nutrients resulting in gas and odor emissions, diet modification has the potential to reduce nutrient output and improve air quality.

Our hypothesis is that by utilizing a low nutrient excretion diet formulation and an alternative manure management strategy, the amount of nutrient output and gas/odor emissions will be reduced over the wean-finish period.


A total of 1, 920 pigs (initial BW = 5.29 kg) were used in a 2 x 2 factorial, wean-finish experiment to determine the effects of diet (control, CTL vs. low nutrient excretion, LNE) and manure management (6 mo. deep-pit, DP vs. monthly pull plug-recharge, PP) on growth performance, nutrient output, and air quality. Pigs were housed in a 12-room environmental building.

Pigs were split-sex and phase-fed to meet or exceed their nutrient requirements (NRC, 1998) at different stages of growth. The CTL and LNE diets were corn-soybean meal based and formulated to an equal Lysine:calorie. The LNE diet formulation had reduced CP and P, increased synthetic amino acids, phytase, non-sulfur trace mineral premix and added fat. Improvements in pig performance were observed over the wean-finish period.

Did Lysine Affect Performance or Odorous Emissions?

Pigs fed the LNE diets were 4.3 kg heavier (131.2 vs. 126.9 kg) at market, gain was increased by 0.03 kg/d (0.83 vs. 0.80 kg/d), feed intake was reduced by 0.16 kg/d (1.95 vs. 2.11 kg/d), and overall feed efficiency was increased by 11.6% (0.43 vs. 0.38) compared to CTL fed pigs (P<0.01). In addition, manure generation was reduced by 0.39 L/pig/d when the LNE diets were fed vs. the CTL diets (4.05 vs. 4.44 L/pig/d, P<0.008).

Excretion of total N, P, and K was reduced (P<0.001) by 27.5, 42.5, and 20.4%, respectively, from LNE fed pigs. Pigs fed the LNE diets had a 25.5, 23.8, 32.3, 18.5, 35.8, and 26.7% reduction (P<0.05) in manure acetate, iso-butyrate, iso-valerate, valerate, and total VFA production, respectively, compared to CTL fed pigs. Using the PP manure strategy reduced manure ammonium N and VFA production by 10.3 % (16.5 vs. 18.4 g/pig/d; P<0.002) and 20.5% (26.0 vs. 32.7 mM/pig/d; P<0.001), respectively, compared to DP strategy. Pigs fed LNE diets had a 13.6% (P<0.001) reduction in aerial NH3 emissions over the wean-finish period compared to pigs fed CTL diets. Aerial H2S and SO2 emissions and odor were not different (P>0.10) between dietary treatments.

Why is This Important?

Feeding LNE diet formulations are effective in reducing environmental impacts of pork production while maintaining growth performance. In addition, utilizing a monthly pull plug-recharge manure management strategy can improve air quality parameters, however can be more labor intensive.

For More Information

Contact us at or (765)496-7718.

By Scott Radcliffe, Brian Richert, Danielle Sholly, Ken Foster, Brandon Hollas, Teng Lim, Jiqin Ni, Al Heber, Alan Sutton – Purdue University

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 “Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture”. This report is not peer-reviewed and the author has sole responsibility for the content.

Air Emission and Energy Usage Impacts of No Pit Fans in a Wean to Finish Deep Pit Pig Facility

What Is Being Measured?

The objectives of this research project are to monitor the indoor air quality of a deep-pit; wean-to-finish pig building over one pig-growth cycle (six months) by semi-continuously measuring concentrations of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), and volatile organic compounds (VOCs) and intermittently measuring particulate matter (PM10) and odor. The project will also monitor semi-continuous emissions of NH3, H2S, CO2, CH4, and VOCs plus intermittent sampling of odor emissions from the barn’s pit and wall exhaust streams over the six month growth period. Energy usage, both electrical and LP gas usage will be measured for both pit and non-pit ventilated rooms over the pig growth, along with pig performance (daily gain, feed efficiency, and death loss) between the rooms.

Current Activities

A cooperating pork producer is being located in southern Minnesota with a tentative starting date of July 1, 2008 for data collection.

Does the Use of Pit Fans Make a Difference in Air Emissions from Deep-Pit Pig Barns?

Air emissions from tunnel ventilated pig finishing barns have been monitored and partitioned between pit and wall fans during the past two years in Minnesota. The results showed that a disproportionate amount of hydrogen sulfide (H2S) and ammonia (NH3) emissions were emitted from the deep pit finishing barn through pit fans even though it was concluded that “pit” ventilation has little effect on the barn’s indoor air quality (figure 1). Thus producers might be able to reduce emissions of these hazardous gases and the associated odor of these gases simply by limiting or not using pit ventilation fans. Such a strategy would save electrical energy use since larger more efficient wall fans could replace the less efficient pit fans.

Figure 1. Hydrogen Sulfide Emissions from a 1200 head pig finishing barn with varying pit ventilation rates during a winter (January 26 to March 4, 2006) period. Contributed to eXtension CC2.5

Why is This Important?

Data collected from the deep pit facility will be used to determine the benefit of pit fans to indoor air quality in swine wean to finish buildings and what impact the use of pit fans has on energy usage and gas, odor, and particulate matter emissions from this stage of pork production buildings .

For More Information

Jacobson, L.D., B.P. Hetchler, and D.R. Schmidt. 2007. Sampling pit and wall emission for H2S, NH3, CO2, PM, & odor from deep-pit pig finishing facilities. Presented at the International Symposium on Air Quality and Waste Management for Agriculture. Sept 15-19, 2007. Broomfield, CO. St. Joseph, Mich.: ASABE

Authors: Larry D. Jacobson, David Schmidt and Brian Hetchler, University of Minnesota

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 “Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture”. This report is not peer-reviewed and the author has sole responsibility for the content.

Simultaneous Treatment of Odor, Volatile Organic Compounds, Hydrogen Sulfide, Ammonia, and Pathogens With Ultraviolet Light

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Is It Feasible to Treat or Reduce Several Air Emissions from Pig Barns at Once?

The simultaneous treatment of odors, gases, airborne pathogens using novel ultraviolet (UV) treatment project addresses a critical need of the control of odor and pathogens generated in commercial swine production. The same technology could potentially be used for other species (e.g., poultry) that are housed in mechanically-ventilated barns. This study will test the potential for using currently available technology for the simultaneous degradation of most offensive odorants, ammonia (NH3), and model pathogens (SIV, BVDV). Such UV light-based technology is suitable for application for ventilation air and could be applied to exhaust air (to treat emissions) and inlet air (to prevent the spread of infectious diseases) for new and existing operations.

The long-term goal is to develop a cost-effective technology for the simultaneous treatment of odor and pathogens in swine and possibly poultry housing in order to limit their impact on air quality and health (both human and animal).


A standard gas/odor system for generating and measuring gases is being used for lab-scale experiments. The system generates 13 odorous gases including hydrogen sulfide (H2S), mercaptans, volatile fatty acids (VFAs), and phenolic compounds responsible for swine odor. NH3 gas and its removal is included. Odor measurement with a standard ASTM method are conducted by the Olfactometry Lab.

Did UV Light Reduce Pathogens and Odorants?

We measured the effectiveness of odor treatment and pathogen inactivation in laboratory scale. Almost 100% removal was achieved for all the compounds tested except H2S and dimethylsulfide using only 1 sec irradiation. Removals of H2S and dimethylsulfide are also significant. Longer UV irradiation times resulted in complete percent reduction of target compounds and odor. Of specific interest is very efficient removal of p-cresol which has been recognized as priority odorant responsible for the characteristic livestock odor. Treatment cost of $0.25 per pig and continuous operation during growing cycle was estimated when the lab-scale results were extrapolated to typical ventilation rates and electricity cost at a swine finish operation in rural Iowa.

Why is This Important?

Comprehensive solutions to swine aerial emissions are expected to be even more urgent in the future. Thus, the proposed study addresses several critically important issues confronting pork and poultry producers, but also has a broader applicability to homeland security, human/animal health, indoor air quality and hazardous waste treatment.

For More Information

Authors: Jacek Koziel, Jeff Zimmerman, Steven Hoff, Hans van Leeuwen, William Jenks, Iowa State University

Read the following articles or visit the Iowa State University odor research website.

Yang, X., Koziel, J.A., Cai L., Hoff, S. et al. Novel treatment of VOCs and odor using photolysis. ASABE Annual International Meeting, 2007, Minneapolis, MN, paper No. 074139.

Koziel, J.A., X. Yang, T. Cutler, S. Zhang, J. Zimmerman, S. J. Hoff, W. Jenks, Y. Laor, U. Ravid, R. Armon, J.H. van Leeuwen. 2008. Mitigation of odor and pathogens from CAFAs with UV/TiO2: exploring cost effectiveness. In the proceedings of the Mitigating Air Emissions From Animal Feeding Operations Conference. Des Moines, May, 2008.

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 “Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture”. This report is not peer-reviewed and the author has sole responsibility for the content.