Mitigating odor and gas emissions is a big challenge facing concentrated animal feeding operations. Biofiltrtion has been recognized as one of the most promising technologies for reducing odor and gas emissions from animal facilities. However, the rate of on-farm biofilter adoption continues to be low. The purpose of this research was to demonstrate, evaluate, and encourage the widespread adoption of biofilters for mitigating odor and gas emissions.
What did we do?
Two vertical down-flow biofilters were constructed on a commercial swine nursery farm. Both biofilter media were shredded wood bark and medium wood bark (1:2 on a volume basis). These biofilters were evaluated under real farm conditions in terms of mitigation of odor and gas emissions. Odor samples were collected using 10 L Tedlar bags and evaluated using a dynamic forced-choice olfactometer. Ammonia and hydrogen sulfide concentrations were monitored on-site by detection tubes. Pressure drop through the biofilter media was also measured on-site using an air velocity meter. A biofilter field day was held on the swine farm to demonstrate their effects and to present biofilter basics. Also, an educational video has been developed to help interested people get familiar with this technology.
Figure 1. (a)biofilter 1 (BF1) and biofilter 2(BF2) with front doors open; (b) biofilters with front doors closed; (c) media and water distribution system in BF2; (d) media and water distribution system in BF1; (e) shredded wood bark; (f) medium wood bark.
What have we learned?
(2) Supporting materials showing biofilter basics and its effects on reducing aerosol emissions are needed to encourage biofilter adoption,
(3) Field days are a good platform for both research and demonstrations of new techniques,
(4) Producer’ collaboration and full participation are very important to make the research a success.
Figure 2. Odor and gas (NH3 and H2S) reduction efficiency and moisture distribution at different media depths of (a) biofilter 1 (BF1); (b) biofilter 2 (BF2).
Figure 3. Reduction efficiency for first stage of biofilter 2 (BF2) at different media moisture contents (MC) (a) NH3; (b) H2S; (c) moisture distribution at different media depths. Shredded wood bark (depth of 127 cm) was used and EBRT was 0.9-1.0 s.
Figure 4. Reduction efficiency for second stage of biofilter 2 (BF2) at different media moisture contents (MC) (a) NH3; (b) H2S; (c) moisture distribution at different media depths. Medium wood bark (depth of 254 cm) was used and EBRT was 1.8-2.0 s.
We will refine the developed educational videos and disseminate results from this study to our stakeholders.
Lide Chen, Waste Management Engineer and Assistant Professor, Biological and Agricultural Engineering Department, University of Idaho firstname.lastname@example.org
Gopi Krishna Kafle, Post-Doctoral Researcher; Howard Neibling, Extension Irrigation and Water Management Specialist and Associate Professor; B. Brian He, Professor, University of Idaho
Contact Dr. Lide Chen at email@example.com for more information.
This project was partially funded by the USDA Natural Resource Conservation Service through a Conservation Innovation Grant. The authors gratefully thank Mr. Dave Roper for his cooperative efforts during this research.
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