Performance of periodically operated-gas phase biofilters during transient loading conditions

Most industrial processes and environmental remediation activities generate large volumes of air contaminated with volatile organic compounds (VOCs). In conventional biofilter operation, gaseous emissions contaminated with low concentrations of biodegradable VOGs are remediated by being passed continuously through packed beds. This paper describes how periodically operated biofilters can be designed as controlled, unsteady-state systems that destroy gas-phase contaminants. Periodic operation, previously limited to applications in wastewater treatment and soil remediation, increases an operator's ability to control the spatial distribution, physiological state, and "robustness" of the microbial communities established within a biofilter while minimizing uncertainties that often accompany design and operation of biological systems. Results are presented from toluene degrading biofilters that used a novel polyurethane foam packing medium. These studies demonstrate how controlled periodic operations can enhance contaminant removal during transient periods of elevated contaminant load.