#07-034

Complete

Date Full Report Received

10/31/2008

Date Abstract Report Received

10/31/2008

Investigation

Institution:
Primary Investigator:
Co-Investigators: David Schmidt

Gas-phase biofilters are a proven method for reducing odor emissions from swine facilities and manure storage units. Woodchip and compost mixtures are commonly used as biofilter media. Widespread use of biofilters is stalled in part due to three issues: 1) the relatively large footprint needed to manage the media pressure drop; 2) concerns about the biofilter media harboring rats; and 3) long term biofilter media compaction. The purpose of this initial project on alternative biofilter media was to evaluate the media’s ability to mitigate these issues. The alternative media were: bag mulch, lava rock, cedar chips, pine bark nuggets, western pine bark and wood shreds. Study results demonstrated that all six media, if seeded with compost and aerated manure, could support microbial organisms that reduced hydrogen sulfide, ammonia and odor emissions in air from a swine manure or gestation barn. The alternative media had larger particles and more porosity than typical woodchip and compost mixtures. The pressure drop, an indication of the amount of electrical energy needed to blow air through the media, across the wood shreds, pine bark and lava rock media were less than across woodchip media. These results are expected to lead to biofilter designs that will need less electrical energy for operation. Gas and odor reductions were variable in part because the air source concentrations were highly variable over a period of minutes. Common woodchip and compost biofilters typically have five seconds of contact in the media. Results from this study indicate that biofilters with media made up of larger particles and having contact times of one second can reduce hydrogen sulfide emissions by between 8 and 90% while those with five seconds of contact time can reduce emissions by between 77 to 100%. These results suggest that alternative media can be used to manage odor and gas emissions while using less energy that conventional biofilters. More research is needed before design and management recommendations can be developed. Contact information: Kevin Janni, kjanni@umn.edu 612-625-3108.