[Experimental study of nitrite accumulation in pre-denitrification biological nitrogen removal process].

It was realized nitrite accumulation in a pilot-scale pre-denitrification process at normal temperature. The influence factors, temperature, pH, FA and DO, for nitrite accumulation were analyzed. The nitrite was accumulated in the beginning time with the DO kept at 0.5 mg/L, however the phenomenon of nitrite accumulation was vanished when the DO increased to 1.5 mg/L. At last the nitrite accumulation was resumed when DO reduced to 0.5 mg/L. So it could be obtained that DO was the main factor to realize nitrite accumulation in the study. It was found that it was possible to keep stable and high nitrite accumulation effectively control DO at 0.5 mg/L.