Microbial Community Analysis on Oxic-Settling-Anaerobic Process by Using PCR-DGGE Assay

In situ sludge reduction of the oxic-settling-anaerobic (OSA) process was investigated in this study and microbial community diversity in the system was analyzed by using a PCR-denaturing gradient gel electrophoresis (DGGE) approach. Comparing to the conventional activated sludge method, the production of excessive sludge in the OSA process was shown to be efficiently reduced by 44-50 % and the organic loading rate was observed to have a slight impact on sludge yield. As demonstrated by the slight variation of Shannon diversity indices (SDI), the dominant microbial composition remained stable in the USA sludge with the increase of N-s. About 63% of clones represented by predominant bands in the DGGE pattern were affiliated with the subclass of beta-proteobacteria. A number of bacteria in the OSA process were phylogenetically related to uncultured bacteria isolated from enhanced biological phosphorus removal (EBPR) sludge.