Proceedings available at: http://www.extension.org/67675 A 1440 cu. ft. woodchip biofilter was designed and built to treat the air coming from the cool season fans of a 2,000 head swine finishing operation. Key lessons learned during construction included improvements for design coordination, materials, and labor. After installation, biofilter moisture, odor performance, and static pressures were monitored. Biofilter moisture required more sprinkling than expected, with two, one hour sprinkler runs a day not keeping up during hot, dry conditions. Dry bed conditions likely led to little effect found during odor monitoring. The biofilter does appear to filter dust quite effectively. High static pressures (>0.2 in. of water) developed more rapidly than expected and prompted closer monitoring. Presented by: Crystal Powers

1. Nebraska Biofilter Case
Study
For more information:
http://water.unl.edu/web/manure/c
ontrol-emissions
Crystal Powers, Rick Stowell
Biological Systems Engineering
University of Nebraska - Lincoln
®

2. Biofilters – the basics
• A biofilter is a bed of organic material
which supports microbes that break
down odorous gases used on buildings
with exhaust fans
• 80-95% odor reduction of air though
biofilter
– During warm weather some air usually
bypasses the biofilter

3. Project purpose
• Demonstrate the design, construction,
and monitoring an on-farm biofilter
• Learn practical lessons about the
construction process
• Determine maintenance needs in the
field

4. 98% o.a.f.f odor setbacks
Without biofilter
With biofilter
Demonstrate odor control
98% o.a.f.f. odor setbacks

5. Design (per room)
• A biofilter was built on a 2,000 head swine finishing
barn and monitored for odor reductions and fan static
pressure.
• Airflow: 12,000 cfm
• Suggested Duct area: 30 sq ft
• Critical Duct area: 12 sq ft
• Empty Bed contact time: 6 sec
• Media depth needed: 20” (24” installed) chipped
recycled pallets
• Bed area: 720 sq ft
• Costs as built: Plenum: $3,600 Beds: $5,840, Labor:
$5,600, Total: $15,040

9. Construction lessons learned
• Coordinate early and often with building designer:
Ensure any changes are carried throughout plans,
plan for electrical access from the start, and build in
water access for sprinklers
• Pit fans switches should be opposite side of biofilter
for easier access and fan wiring ducts should be
located so don’t go through biofilter walls
• Put gutters on the roof to limit erosion
• Make sure biofilter media is clean
• Ducting from fans to plenum would be great to have
as off-the-self equipment
• Construction took much more time than expected:
approximately 320 total hours

10. Maintenance lessons learned
• Pit access must be simple
• Snow drifts are heavy, so plan for extreme events
• To keep the biofilter moisture in optimal ranges,
sprinkling for 1 hour a day was not sufficient
• Limited biofilter bed moisture limited the odor
reduction, however, most of the dust was filtered
out.
• Static pressures on the fans increased more quickly
than expected, up to 0.35 in of water when all fans
were operational.
• At high airflows, ~30% pressure is from ducting

11. Acknowledgements
• A cooperative effort of the University of
Nebraska–Lincoln Extension and Pork
producer Terry O’Neel. Funding to
support this effort was provided by the
Nebraska Environmental Trust and the
Nebraska Pork Producers Association