[Autotrophic biofilters for oxidation of nitric oxide]

Carbon foam, a kind of new engineering material as packing material was adopted in three fi 50.8 mm biofilters with different pore dimension and a domesticated autotrophic nitrite nitrobacteria to investigate the purification of nitrie oxide(NO) in air stream. The biofilm was developed on the surface of carbon foams using nitrite as its only nitric source. The moisture in the filter was maintained by ultrasonic aerosol equipment, which can also minimize the thickness of the liquid film. The liquid phase nitrification test was conducted to determine the variability and the potential of performance among the three carbon foam-based biofilters. The investigation showed that during the NO influent concentration of 200 to 800 g/(L.min), the 24PPC (Pores Per Centimeter) carbon foam-based biofilters had the greatest potential, achieving removal efficiencies of 94% to 98%. The 8PPC and 18PPC carbon foam-based biofilters achieved removals efficiencies of 15% to 21% and of 30% to 40%, respectively. Further research showed the potential for this system to remove NO from an air stream on the base of a steady removal efficiency of 41% to 52% was attained for the 24PPC carbon foam-based biofilter at specified NO influent concentrations of 66.97 to 267.86 mg/m3 and an empty-bed residence time of 3.5 minutes.