As a result,it has many advantages over the conventional system:nitrification and denitrification could take place simultaneously in the aeration tank and then it was unnecessary to recirculate the nitrate rich liquid to the anoxic thank for anaerobic denitrification or construct additional advanced treatment systems for nutrients removal; (ii) it was highly flexible to be merged into existing biological treatment systems to enhance nutrients removal efficiency without the requirement for extra land occupancy; (iii) the resistance capability to fluctuations would be greatly enhanced because the maximum growth rates of the heterotrophic nitrifiers are five to ten times than those of the autotrophic nitrifiers. In view of the above consideration, the proposed bioaugmentation strategy should be very promising owing to its incomparable advantages such as reducing energy consumption and waiving additional