Identification And Characteristic Of Two Strains Of Heterotrophic Nitrifiers

The nitrogen pollution is the main reason causing water eutrophication, and the removal of nitrogen has become a hot topic in wasterwater treatment field as water eutrophication become even worse. Because of the different requirement of the different nitrifiers and denitrifiers for nourishment , the process of removal of nitrogen is very complex and the application is limited. The find of heterotrophic nitrification provides a new method for developing the application of the biological removal of nitrogen. Because of their advantages such as enhancing the treatment effect, reducing the area and reducing the treatment process flow etc, heterotrophic nitrification process has been widely put attentions.Two strains of heterotrophic nitrifiers, named Z5 and Z8, is isolated from bio-ceramic reactor. The analysis based on 16SrDNA showed that the strains are the relative of Pseudomonas aeruginosa and Acinetobacter sp. with 100% and 99% sequence similarity respectively. Under the conditions, the ammonium removal rate reached 57.95% and 63.86% respectively. The initial removal of ammonium is the critical factor to the organism growth. Meanwhile, 86.93% and 89.57% of the NO3—N removal rate can be gained, which indicated that Z5 and Z8 possessed high effective denitrification. During the whole growth of Z5 and Z8, there is no nitrite and nitrate accumulation.The process of removing ammoniac nitrogen was done by setting the heterotrophic nitrification bacteria on the sequencing batch reactor. And the efficiency of ammoniac nitrogen removal can reach up to 82.96%, when the reactor works smoothly. The nitrite concentration of effluent was in a low level and the maxiuma value was no more than 3.84mg/L. At the same time, the efficiency of COD was 54.72%, which presents the coinstantaneous removing of both organic and ammoniac nitrogen.The PCR-DGGE profiles showed that shift of microbial diversity correspond to the effect of nitrate removal.1d and the 15d similarity is 75%, which microbial diversity is the highest. 1d and the 30d similarity is the lowest which is just 52.94%, 15d and the 30d.similarity is 70.59%. Z5, Z8 were dominated bacteria in sequencing batch reactor.