Abstract
In this study, research of optimal conditions for nitritation with immobilized nitrifying bacteria on hydrogels and identification of their bacterium which producing with speedy and alternatively only NO2- from 3,000 to 5,300 ㎎/L of NH4-N was carried out. The fraction of biocatalysts was approximately 10 wt% in 4L of a bubbling vessel in a batch reaction. The amount of produced NO2- increased with rising pH(pH 7.0 to 8.0).At pH 8.0, 5,300 ㎎/L of NH4-N completely disappeared, and 5,058 ㎎/L of NO2-N was produced. From the result of gene analysis, it was suggested that this nitritation reaction without production of NO3- was caused by the bacteria Methylobacterium extorquens DM4, which acts as a nitrite-reducing enzyme. It is expected that high concentration NO2- obtained with high-speed biologic treatment can lead to the development of a new disappearance-type nitrogen eliminating system that is cheap and compact, followed by biologic treatment.
