Treatment of High-Concentration Ammonium Wastewater with Immobilized Nitrifying Bacteria and their Microbial Ecology

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 NO sub(2) super(-) from 3,000 to 5,300 mg/L of NH sub(4)-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 NO sub(2) super(-) increased with rising pH(pH 7.0 to 8.0).At pH 8.0, 5,300 mg/L of NH sub(4)-N completely disappeared, and 5,058 mg/L of NO sub(2)-N was produced. From the result of gene analysis, it was suggested that this nitritation reaction without production of NO sub(3) super(-) was caused by the bacteria Methylobacterium extorquens DM4, which acts as a nitrite-reducing enzyme. It is expected that high concentration NO sub(2) super(-) 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.