| Fluidized-pellet-bed (FPB) bioreactor is a kind of new technology of wastewater treatment which combines self-pelleting fluidized bed technologies and activated sludge process. In one treatment site it integrates coagulation-granulation technology and highly effective solid/liquid separation technology, and is of high removal efficiency of suspended solids and organic pollutants.The effect of treatment of FPB is very well, which reaches the effect equivalent to that of secondly treatment of conventional activated sludge process. This has an important relationship with the biodegradation effect and adsorption effect in FPB. As a result, it is necessary to study the distribution of DO and the microbial community structure in FPB, which can reveal the mechanism of pollutant metabolism transformation systems in FPB.Microbial community structure and the pollutants removal characteristics were studied using a fluidized-pellet-bed (FPB) bioreactor treating artificial wastewater. By preaeration, the dissolved oxygen concentration could be kept as about 8mg/L. Good sludge granules formed in the FPB by the chemically intensifying action of PAC and PAM under lmm/s up-flow rate. Through experiments we get the following conclusions(1) The total bacteria reached about 108 CFU·g-1.(2) FISH experimental results showed that the proportions of nitrite oxidizer and ammonia oxidizers were 11.4%,11.9%,10.5%; 9.8%,8.8%,8.4% respectively.(3) The SOUR in the bottom section of the FPB columns was higher than the top, and DO was also mainly consumed in the bottom section. (4) The removal of COD well followed the first-order kinetics. There was a tendency of increase of nitrate-nitrogen and decrease of ammonia-nitrogen along the FPB column, indicating a significant nitrification activity.
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