A mobile biofilter testing laboratory was developed where two-stage biofilters filled with western cedar and hardwood chips were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. An automatically controlled water supply system was tested and used to control media moisture content. Odor concentrations from theinlet and biofilter treatments, gas flow pressure drop, leachate pH and ammonia concentration, and water consumption were monitored.Results indicate that the water supply system tested in this study can keep wood chip media at a high and stablemoisture content of 72% ± 3% (western cedar) and 62% ± 3% (hardwood)with a 6.4 L/m3-day water supply. Western cedar (WC) chips achieved an average reduction efficiency of 51%, 83%, and 41% for odor, H2S, and NH3, respectively, when keeping the WC moisture content at 72% and the empty bed residence time (EBRT) between 3.7 and 5.5 s. A linear relationship between media unit pressure drop and unit airflow rate was observed with two-stage biofilters having an advantage in potentially reducing media compaction.Leachate pH and NH3 concentration were measured with pH levels in the 7.2 to 7.9 range with the NH3 concentration in the 198 to 1300 mg/L as N range.The effects of three different levels of media moisture content shows that proper moisture content is a key factor for the success of wood chip biofilters, but is not a substitute for inadequate EBRT.