A cost benefit approach to reactor sizing and nutrient supply for biotrickling filters for air pollution control

In the present paper, a general model was developed that allows the selecti on of the most cost-effective operation of biotrickling filters for air pol lution control. The model was demonstrated for a typical case of industrial pollution. 10, 000 m(3) h(-1) airstream contaminated with 1.5g m(-3) tolue ne. The effects of nitrogen (as nitrate) loading on the pollutant eliminati on capacity and an the rate of biomass growth were considered. Using model simulations, the influence of the nitrate loading on the overall treatment cost was quantified and an optimum nitrate loading was determined. The resu lts suggest that biotrickling filtration is very competitive compared to co nventional treatment technologies. For the case studied a treatment cost op timum was obtained at a nutrient loading of 8 g N-nitrate per cubic meter b ed volume per day. This represents a relatively severe nutrient limitation. The range of nutrient loading for cost effective treatment was about 4 to 30 g N-nitrate m(-3) d(-1). Overall, the approach presented herein is widel y applicable for the determination of the best reactor design and the optim um reactor operating conditions.