Masters Theses

Date of Award

5-1999

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

Luther R. Wilhelm

Committee Members

Alan Mathew, John Wilkerson

Abstract

In this study, air quality measurements were made in swine production confinement facilities to monitor the internal environment. Two buildings were monitored throughout most of this study. The two buildings were identical except for the use of a pit ventilation system in one of the buildings (Bam B). The main focus of the monitoring system used in this study consisted of electrochemical gas sensors to continuously measure gas concentration levels (ppm) at human level (2 m). The gases measured were Oxygen, Carbon Monoxide, and Ammonia and Hydrogen Sulfide, which are the major gases of concern. Other measurements included that of environmental conditions, such as temperature, relative humidity, and solar radiation, and other key factors affecting gas levels, including monitoring the building's ventilation system. Data were averaged over each 30-minute period and recorded by a data logger. These data were then transmitted by the use of a cellular communication/modem system to the department at the university, which was located more than 300 miles away from the research site. Results obtained from this study found the major manure gases, ammonia and hydrogen sulfide, to be consistently lower in the pit ventilated building (Bam B) when compared to the non-pit ventilated building (Bam A). Gas levels were monitored over two successive winters, when ventilation levels were at their lowest due to environmental conditions. Significant differences (p < 0.05) were found between gas levels taken in the two buildings and levels were found to change, most of the time, inversely proportional to that of temperature. Gas levels were found to be directly affected by ventilation levels during cold weather, as found when monitoring the ventilation operating frequency. As ventilation levels were decreased in response to cold weather, gas levels increased due to accumulations of levels within the "closed" unit and vice/versa.

Measurements were also taken at the pit exhaust and inside the pit ventilated Bam B. As expected, levels of ammonia and hydrogen sulfide were found to be significantly higher (p < 0.05) at the pit exhaust area when compared to levels taken inside. These measurements were taken during the warm summer months, when ventilation rates were high; and gas levels were found to be directly proportional to temperature.

Measurements were also taken at animal level to see if there were differences in gas concentrations between animal and human (2 m) level. Slight differences were found between the two areas of measurement, but reliable conclusions cannot be made about why differences occurred between high and low measurements because of the inconsistent data collected.

Overall, the environments within the swine confinement units were found to be very cyclical and dependent upon environmental conditions and changes in ventilation. The use of a pit ventilation system was found to be beneficial in the control of manure gases, especially during periods of cold weather, when ventilation rates were low.

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