Potential Improvement in Biofilter Design through the Use of Heterogeneous Packing and a Conical Biofilter Geometry

Due to the heterogeneous distribution of microbial activities in a biofilter, biomass accumulation and clogging often occurs in the inlet sections, leading to a considerable increase in the total pressure drop and shortening of the bed material life span. We propose two new design concepts to optimize biofilter performance and reduce pressure drop by distributing biomass or pressure drop more homogeneously. One concept involves using a heterogenous packing system where the biologically more active inlet sections have larger particles and the less active outlet sections have smaller particles. This provides a more even distribution of microbial activity and pollutant degradation, resulting in a considerable reduction in the total pressure drop. The other concept involves using a conical biofilter geometry instead of the conventional cylindrical form. The varying crosssectional area counteracts an uneven distribution of microbial activities and thus achieves a more uniform pressure drop along a biofilter. Experimental and/or simulation results showed that heterogeneous packing and conical geometry could result in more cost-effective biofiltration.