Abstract：Acidobacteria is an important phosphorus removal bacteria in the sequencing batch reactors (SBR) system, and its effects on phosphorus removal process should not be ignored. Sludge retention time (SRT) is an essential parameter of the design and operation of the SBR process. If the SRT changed, the phosphorus removal effect of SBR would also change. In order to inspect the phosphorus removal effect, the SRT of SBR system was tested for 10, 15, 20 and 30 d. PCR-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community structure of acidobacteria in the activated sludge. The results indicated that the removal rate of total phosphorus reached 90%, 74%, 52% and 31% at the sludge of 10, 15, 20 and 30 d, respectively. The removal effect was the best at the sludge of 10 d, and short sludge age was more advantageous to the total phosphorus removal. Acidobacteria was sensitive to the changes of the sludge age conditions, and the dominant strains of the Acidobacteria changed frequently. The diversity index reached 0.87 at the sludge of 10 d, and dropped to 0.81 at the sludge of 30 d. The results indicate that the Acidobacteria is more adapting to the environment of long sludge age.
