Determining Pressure Drop Through Compost-Wood Chip Biofilter Media

Biofilters are an effective air pollution control technology that uses microorganisms to breakdown gaseous contaminants. Compost and wood chip media mixtures ranging from 30:70 to 50:50 percent by weight are recommended for removing odors and hydrogen sulfide from livestock wastes. The relation between unit flow rate through the biofilter media and the unit pressure drop across the media is needed for biofilter design. The purpose of this project was to develop a method for characterizing compost and wood chip mixtures and predicting the relation between flow rate and pressure drop. A field method for estimating the media’s percent voids was highly correlated with sieve analysis results. Relations to estimate the unit pressure drop given the unit flow rate and percent voids were developed for media with between 40 to 60% voids. These can be used to evaluate alternative biofilter designs and for selecting fans with adequate fan performance characteristics.