Development of gas phase bioreactors for the removal of nitrogen oxides from synthetic flue gas streams

Thermophilic denitrifying bacteria indigenous to composts and soils are capable of converting NOx to environmentally benign nitrogen via a dissimilatory reductive pathway. The present study compares the performance of three bioreactor packing materials (compost, perlite, and biofoam) for the removal of nitric oxide (NO) from a simulated wet-scrubbed combustion gas. Although all three materials performed well (>85% NO removal) at residence times of 70–80 s, the compost performed better than the other materials at shorter residence times (13–44 s). The feasibility of biological NOx conversion processes will depend on the combined factors of NOx removal ability and pressure drop. The results presented here suggest that the compost, perlite and biofoam systems, subject to further optimization, offer potential for the biological removal of NOx from gas streams.