| Because of detachment, there are two kinds of biomass in the biofilm reactors: the attached biomass (biofilm) and the suspended biomass. The structure of biofilm and the activities of both the attached biomass and the suspended biomass would be deeply affected by detachment.The research was carried out with an anoxic moving bed biofilm reactor (MBBR). And the characteristics of biomass were studied at different mixing intensions (100rpm, 120 rpm, 150 rpm, 200 rpm). The following results were obtained:(1) The biomass increased with the stirring intension. Under 100rpm, 120 rpm, 150rpm, and 200 rpm, the attached biomass reatched to 33.7 mg/g, 53.2 mg/g, 82.3 mg/g, 98.7 mg/g carriers, respectively; and the total biomass in the reactor maintained at 13.41g, 21.56g, 32.25g, 34.33g, respectively; the attached biomass maintained at 12.05g, 19.02g, 28.6g, 30.84g, respectively; and the suspended biomass maintained at 1.36g, 2.54g, 3.65g, 3.49g, respectively. Although the biomass were variable at 4 diflFerent rpm, the attached biomass and the suspended biomass was about 89% and 11% that of total biomass, respectively.(2) The activity of biomass decreased with the stirring intension. Under 100rpm, 120 rpm, 150 rpm and 200 rpm, the NUR of the total biomass achieved to 30.1mg/g .h, 21.5mg/g.h, 12.2mg/g.h,7.5mg /g.h, respectively; and the NUR of the attached biomass reatched to 32.1mg/g.h, 22.9mg/g.h, 13.2mg/g.h, 7.9mg /g.h, respectively; and the NUR of the suspended biomass reatched to 12.4mg/g.h, 11.0mg/g.h, 4.0mg/g.h, 3.7mg /g.h, respectively.(3) The yield coefficient of biomass increased with the stirring intension. Under 100rpm, 120rpm, 150rpm, and 200 rpm, the yield coefficient was 0.315 gSS/gCOD, 0.351 gSS/gCOD, 0.396 gSS/gCOD, 0.390 gSS/gCOD, respectively.(4) The granules were found in the stirred anoxic denitrifying MBBR at 200rpm.(5) Ca and Mg were accumulated in the denitrifying biofilm. And the deco CaCO3 and Mg(OH)2 at 700 ℃ led to the error results of the experiment.
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