Performance of Woodchip Based Biofilters Treating Cyclic Air Emissions from the Forest Products Industry, 1999 Environmental Conference Proceedings

Christina Dirk-Faitakis

Dr. D. G. Allen

Department of Chemical Engineering and Applied Chemistry

University of Toronto

Biofiltration is an air pollution control technology that has potential for treating large volumes of air emissions containing low concentrations of pollutants typically found in the wood products and pulp and paper industries. Air emissions from certain processes (eg. brownstock washers, tank vents, and press vents) are cyclic in nature, having pollutant concentrations varying on time scales of the same order of magnitude as the residence time of a biofilter.

The objectives of this research are to examine the impact of cyclic loading on biofilter performance. Our experiments involve running three biofilters in parallel with all conditions the same except the inlet concentration of the pollutant. One biofilter (control) receives a constant concentration stream; the other two biofilters have the inlet pollutant concentration varying in a sinusoidal fashion with a given period and amplitude. All three biofilters receive the same average pollutant loading.

At the given set of operating conditions with a cycle frequency of 10 minutes, all three biofilters have similar removal rates and are able to achieve >80% removal with a loading rate of 30 g  -pinene/m 3 bed/hr. These results indicate that steady state and cyclic operation are similar at this cycle frequency and that periodic operation is not a problem for a biofilter. A maximum elimination capacity of 40 g  -pinene/m 3 bed/hr was observed across the first section of the biofilters. Nutrient and humidity requirements play an important role in maintaining high levels of  -pinene removal.