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 selection of the most cost-effective operation of biotrickling filters for air pollution 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) toluene. The effects of nitrogen (as nitrate) loading on the pollutant elimination 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 results suggest that biotrickling filtration is very competitive compared to conventional treatment technologies. For the case studied a treatment cost optimum was obtained at a nutrient loading of 8 g N-nitrate per cubic meter bed 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 widely applicable for the determination of the best reactor design and the optimum reactor operating conditions.