Odor reduction during biofiltration as affected by air flow rate and media moisture content

Abstract. A mobile biofilter testing laboratory was developed where two types of wood chips (western cedar and hardwood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The biofilters were run continuously for 12 weeks at different air flow rates resulting in variable empty bed residence times. During this test period, a dynamic forced-choice olfactometer was used to evaluate odor concentrations from both the control plenum and biofilter treatments. Analyses of separated odors were carried out using a gas chromatography-mass spectrometry-olfactometer (GC-MS-O) system. Olfactometry results indicated that both types of chips achieved significant reductions in odor and hydrogen sulfide concentrations. GC-MS-O results showed both treatments reached high reduction efficiency for four main groups of odorous compounds. Effects of three different levels of media moisture content were also evaluated. The results showed that proper moisture content is a key factor for the success of wood chip-based biofilters.