MICROBIAL DIVERSITY AND COMPOSITION IN TWO FULL-SCALE WASTEWATER TREATMENT PLANTS (WWTPS) IN SHANGHAI

The microbial diversity and composition in two full-scale wastewater treatment plants (anoxic/aerobic process and activated sludge process) were investigated by several molecular methods. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the microbial diversity in anoxic/aerobic (A/O) process was higher than that in activated sludge (AS) process. Compared to AS process, the anoxic and aerobic reactors in A/O process had more similar community structures. It is very interesting that the Thiothrix sp. was detected as dominant species in AS process. The results of clone library also indicated that 33 clones were close to Thiothrix sp., accounting for 32.0% of total clones in AS process. Real-time PCR results further confirmed that Gammaproteobacteria was also identified as dominant species in AS process. The results of SV(30) in the plants indicated that it appeared sludge bulking in the AS process. Therefore, it is inferred Thiothrix sp., which belonged to Gammaproteobacteria, may play an important role in the development of sludge bulking.