Effect of key parameters on nitric oxide removal by an anaerobic rotating drum biofilter

A bench-scale anaerobic rotating drum biofilter (RDB) was used to demonstrate its ability to treat off-gas containing nitric oxide (NO), by examining the inlet NO concentration and operating temperature as the selected operational parameters. After 30 days' start-up, the long-term stable performance of the RDB was investigated for 100 days. The inlet NO concentration fluctuated between approximately 90 and 433 mg m3, while the removal efficiency was maintained at 60-85%, and the average elimination capacity was 10.4 g m(-3) h(-1). With the inlet NO load increasing from 150 to 1300 mg m(-3), the elimination capacity of the RDB increased from 3 to 26 g m(-3) h(-1) while the removal efficiency decreased sharply from 86% to 40%. At a lower range of NO concentrations (< 150 mg m(-3)), the temperature had no visible effect on the removal efficiency, whereas if NO concentrations were higher than 150 mg m(-3), a non-negligible enhancement of NO removal was found when the temperature was gradually raised from 25 degrees C to 30 degrees C. The optimal temperature was around 30 degrees C. The results proved that the RDB had more advantages over a traditional bioreactor in terms of low mass transfer resistance, high effective utility of packing materials, high even distribution of biomass and no biomass clogging of packing materials. The RDB proved to be an effective treatment process for NO removal.