Ammonia removal by two strains of heterotrophic nitrifying bacteria

Two strains of heterotrophic nitrifying bacteria, ZW2 and ZW5, isolated from a bio-ceramic media reactor were studied for their characteristics of nitrification and nitrogen removal. Based on analysis of physiological and biochemical characters and sequence analysis of the 16S rDNA, strain ZW2 and ZW5 were identified as Pseudomonas sp. and Alcaligenes faecalis, respectively. The nitrification and denitrification could occur by the strains when they utilized organics. After 60h culture, the nitrogen removal rates by the strains were 43.90% and 48.52%, respectively. And COD removal rates by the strains were 67.48% and 78.21%, respectively. During the incubation process, there was almost no nitrite and low nitrate accumulation. Therefore, the two heterotrophic nitrifying bacteria had aerobic denitrification ability.