Biofilter media characterization and airflow resistance test

The physical and chemical properties of ten organic (i.e., five types of wood mulch, two types of compost, peat, sludge, and soil) and one inorganic (i.e., activated carbon) biofilter media were evaluated. The density, porosity, pH, total carbon, total nitrogen, organic matter content, particle size distribution, and airflow resistance of each medium and their mixtures were tested by using standard methods. Airflow resistance of each medium was tested in a 1.0 m × 0.6 m × 0.6 m (L × W × H) testing chamber, and the results were fitted into a standard equation. It was observed that particle size, moisture content, compaction, and bed thickness of media have significant effects on airflow resistance. Based on these results, an empirical "de-rating" modification was developed to improve the equation used to predict pressure drop across biofilters. This research aims to provide a useful database of widely used media for biofilter design.