Document Type

Thesis - University Access Only

Award Date

2006

Degree Name

Master of Science (MS)

Department / School

Agricultural and Biosystems Engineering

Abstract

Concerns over odor and gas emissions from livestock production facilities have increased in the United States. Biofilters have been demonstrated to be an effective technology in reducing odor and pollutant gas emissions from these facilities. Large horizontal biofilter media beds sometimes prevent application of this technology to building layouts. A vertical bed biofilter may be an effective alternative. One potential problem with vertical biofilters is that the biofilter media settles over time, causing a non-uniform airflow through the biofilter from top to bottom. Another problem with both horizontal and vertical bed biofilters is the control of moisture in the biofilter for optimum pollutant and odor removal efficiencies. The research objective was to develop a design for a vertical biofilter to achieve uniform airflow as the media settles and test a biofilter moisture control system. One way to achieve uniform airflow through a vertical bed biofilter as the media settles is to slope one of the side walls. To develop a design strategy for vertical biofilters, six test biofilters were constructed at two thicknesses and three side wall slopes. The three slopes tested were at 0, 4.8, and 9.6 degrees. Airflow was measured from top to bottom on the vertical biofilters to determine variation in airflow. A 9.6 degree wall construction produced the least airflow variation after the media had settled. To achieve the second objective of testing a moisture control system for biofilters, a laboratory scale biofilter was constructed to test a Watermark Electronic Module (WEM) irrigation control system. Using the WEM, moisture was able to be kept above the desired minimum 40% moisture, allowing for maximum pollutant and odor removal using biofiltration. In addition to the findings on slope and moisture control, other findings were also obtained. Odor and hydrogen sulfide levels were reduced by 50-80% in the vertical bed biofilter. Soaker hoses used for irrigation were found to be more effective when place on top of the biofilter media rather than hung vertically through it. The majority of media settling happened initially, during the first few months of biofilter operation. Pressure drop was found to be a factor in design, with the 9.6 degree biofilters only keeping the pressure below the desired maximum 62 pascals 52% of the time. The vertical bed biofilter remained in operation throughout the year, even during cold winter months because of heat obtained from barn exhaust air. The impact of this research is that livestock producers will be helped to achieve greater odor and airborne pollutant reduction as a result of this research.

Library of Congress Subject Headings

Filters and filtration

Odor control

Moisture

Air -- Purification -- Equipment and supplies

Format

application/pdf

Number of Pages

71

Publisher

South Dakota State University

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Rights Statement

In Copyright