EFFECT OF NITRIC OXIDE VINTILATION ON NITROUS OXIDE PROCUNTION BY AMMONIA OXIDIZNG BACTERIA

Abstract

 In this study, we examined the physiological function of nitric oxide (NO) produced in a trace amount in the nitrification process as an influencing factor on nitrous oxide (N₂O) production. Nitrifying bacteria was cultivated with inorganic substrate in the sequencing batch reactor. 200ppm of NO was forcedly ventilated at 20ml/min during the aeration process or stirring process during the cycle. In the system exposed to NO in the aeration process, although an increase in the N₂O conversion rate was confirmed, it was suggested that the direct effect of NO removing the influence of DO and nitrite may decrease N₂O productivity. On the other hand, when NO exposure was performed in the stirring step, a decrease in the N₂O conversion rate was confirmed, it is suggested that NO inhibits the production directly when DO is about 20% or less, and conversely it may be promoted at about 20% or more. In the actual sewage treatment plant, the DO value is often 20% or less, suggesting the possibility of using NO as N₂O production inhibiting factor and management index.