[Isolation, identification of two aerobic denitrifiers and bioaugmentation for enhancing denitrificaition of biofilm under oligotrophic conditions].

Two aerobic denitrifying bacteria were isolated from the sludge of municipal wastewater treatment plant by enrichment, preliminary screening with BTB culture medium and the denitrification potential test and identified through 16S rDNA sequence analysis. Then they were bioaugmented to oligotrophic biofilm system respectively, aiming to enhance the denitrification capacity. The two strains were identified as Pseudomonas aeruginosa and Pseudomonas putida respectively. They could remove 78% or 82% of the total nitrogen in the simulate wastewater when existed alone. And the total nitrogen removal efficiency of the biofilm system reached 68% and 64% after bioaugmentation with two trains, increased by 47% and 43% compared to the control, respectively. Meanwhile, the ammonia nitrogen was nearly 100% removed. It can be concluded that two aerobic denitrifiers can enhance the denitrification of biofilm system significantly under oligotrophic conditions and will not inhibit the nitrification process, therefore can help biofilm system achieve simultaneous nitrification and denitrification.