Abstract: Procaryotae diversity on the biofilm of carrier and their function to excess sludge demineralization in gravel contact oxidation reactor (GCOR) were studied by constructed 16SrRNA library, PCR-based molecular surveys of environmental 16S rDNA genes. The sequence analysis of 16S rDNA genes indicated that biofilm bacterial communities were composed of Proteobacteria, Bacteroidetes, Nitrobacteraceae and Unclassified bacteria group, respectivly. The most abundant sequences were those related to β-Proteobacteria group (20% clones from biolfilm). Next were those related to γ-Proteobacteria (20% clones from biofilm) and Bacteroides (about 13% clones from biofilm). A different kinds of bacteria contributed to excess sludge decrement were associated with uncoupled metabolism, diverse bacterial interactive behaviour, domination of slow growers and cryptic growth.

Key words: gravel contact oxidation reactor (GCOR), biofilm of carrier, 16S rDNA library, procaryotae diversity