Larry D. Jacobson, BAE Dept. Univ. of Minnesota
June 30, 1999
Project Objective:
The objective of this project was to develop a database of outdoor air quality (odor, hydrogen sulfide, and possibly other airborne contaminants) from geographically distributed livestock and poultry farms, including both the manure storage system and the housing facility sources.
Background:
Livestock producers are concerned over the odors that are generated from their operations. The effect of odors, not only on their neighbors, but also on there owns family and employees, are impacting producers in a variety of ways. Some individuals are implementing management strategies to reduce the impact while others are considering odor control technologies. However, little on-farm odor data exists to assist in these decisions.
This project includes measurements from different types of manure storage systems and animal production facilities. Also, hydrogen sulfide concentrations were measured along with odor for most of the samples collected in this study because of the state’s H2S ambient air standard. In addition, during the later half of 1998, ammonia concentrations were recorded on air samples collected as a result of the growing concern over this particular gas level in the ambient or outdoor environment.
Producer Selection and Location:
Air samples were collected during the spring, summer and fall (1998) from 19 selected animal manure storage system sites, plus 28 different livestock and poultry buildings. All of these sites are located in one of three regional "clusters", roughly 30 miles in diameter, in the southeast, southwest, and central Minnesota. The selected animal production sites includes swine, dairy, beef, turkey, and broiler operations.
Data Collection and Experimental Design:
All air samples were collected in 10-liter tedlar bags immediately above the surface of the stored manure with a flux hood or chamber and a commercial vacuum box to avoid capturing any odors from other sources. The building air samples were collected in similar bags from the discharge side of building exhaust fans in mechanically ventilated structures or in the discharge air from naturally ventilated building.
Air samples collected were analyzed by olfactometry, using a panel of eight people to determine odor threshold. Hydrogen sulfide (H2S) concentrations were measured by a JeromeTM meter. Colormetric tubes were used to measure ammonia (NH3) levels.
Results:
A list of the air quality emissions from the selected manure storage units and the animal buildings are given in the attachments to this report. It can be seen from the two attached tables that data from different collection dates during the sampling season are included. This is apparent by the multiple data entries for most of the individual storage units and buildings.
The gas and odor data are presented in concentrations (part per billion, ppb; parts per million, ppm; and odor units, o.u. for H2S, NH3, and odor respectively) which is directly what was measured. Also, the emission rate for each of these contaminants are tabulated, which is a calculated value, determined by multiply the concentration and the ventilation or air flow rate coming from the storage unit or building. It should be stressed that the gas and odor concentrations and emission rates listed in these tables are SOURCE (collected at the surface of manure storage units or from the exhaust air of buildings) values and NOT measured downwind of the animal production units or at the property line of the farms. With the exception of the odor concentration values, some data is missing for the concentration or emission values. The reasons are that some samples were not measured for H2S and NH3 due to equipment problems or, for the case of ammonia, measurements were not started until midway through the sampling period. The missing emission data was most likely due to the inability to determine the airflow or ventilation rate for the odor source from the information gathered which made it impossible to calculate the emission rate.
The hydrogen sulfide, ammonia, and odor concentrations and emissions for cattle (primarily dairy) buildings and manure storage units are listed first in both tables. Facilities varied in size from a low of 45 up to 350 cows. All of the manure storage units sampled from dairy farms were earthen basins. Odor and H2S concentrations varied considerably, even for the same basin, over the course of the sampling period from April to September. One of the storage basins listed did produce more odors and H2S than the others measured as indicated by the higher emission rates. Ammonia concentrations were relatively low (compared to other species) for all the earthen basins measured. Dairy building odor and H2S concentrations and emissions were less and much more consistent than the manure storage values. Again, NH3 levels reported were quite low when compared to values for other animal species.
The next set of data listed in the tables is the H2S, NH3, and odor concentrations and emissions for pig buildings and manure storage units. Both the manure storage unit’s and building’s odor and H2S levels for pigs are approximately one order of magnitude (a factor of ten) higher than those found for dairy. The amount of odor and H2S released from the sources (emission rate) is also larger than for dairy units although not to the same extent as the concentrations. Ammonia concentrations and emissions are slightly higher than the values reported for dairy although again not by a large amount.
The final set of data listed in the tables is for poultry buildings. No data is listed for manure storage units for poultry since manure is commonly stored inside the barn as a manure pack or litter which we chose to call a building source. The H2S and odor concentrations and emissions are similar to those of dairy buildings, while the NH3 concentrations and emissions are about equal to those found in pig buildings. Only one poultry building had relatively high ammonia levels (and thus emissions) which is the common perception among those familiar with air quality issue for animal facilities.
Summary:
This database establishes some actual source air quality concentrations and emission rates from animal production units in Minnesota. Although it represents only 29 sites in the state it is a good start in building a larger base of information concerning outdoor air quality. Hopefully this will serve as a reference for decision making by policy makers, designers of systems, and producers.