Abstract
A study was performed to investigate the effects of packing material's adsorption characteristics on biofilter performance and microbial/environmental stratification along the biofilter bed height. Two identical parallel experimental lab-scale biofilters, loaded with Perlite and granular activated carbon (GAC), respectively, were divided into four sequential individual reactor sections to allow separate monitoring of styrene degradation, leachate pH, and microbial composition along the bed height. Substantially higher maximum elimination capacity at pseudo steady state (>50 g m−3h−1, >150 g m−3h−1 per one section) was achieved in the GAC-packed biofilter compared to the Perlite biofilter (ca. 13–17 g m−3 h−1). Experiments with varying residence time at a constant mass loading below the threshold for breakthrough indicated that the critical factor contributing to the greater performance of the GAC biofilter may be styrene partitioning into the packing material (“buffering”) rather than other transport/kinetic factors. As a result, the GAC-based biofilter exhibited smoother performance and higher leachates' pH between the four consecutive reactor sections which, in turn, contributed to greater microbial composition stability along the bed height.