| In order to improve the ammonium-nitrogen (NH4+-N) biodegradation rate, a suspended carrier was exploited and biofilm was cultivated in three different phases in a sequencing batch reactor (SBR). A flimsy honeycomb-shape biofilm was formed between the endocentric columns on the suspended carrier，which increased the cling amount of nitrobacteria and provided the better condition for nitrobacteria. The bioreactor was operated at the temperature ranges of 24～29℃ and pH between 7.8 and 8.2. When the influent COD and NH4+-N concentrations varied in a range of 140～300 mg?L-1 and 40～78 mg?L-1, respectively, under 90 min aeration, the effluent concentrations were less than 40 mg?L-1 and 2 mg?L-1, respectively. Under 180 min aeration, the influent COD concentration varied from 150 to 350 mg?L-1 and NH4+-N concentration in the range of 80～130 mg?L-1, the effluent concentration below 45 mg?L-1 and 3.5 mg?L-1, respectively. The results indicated that the ammonium-nitrogen biodegradation rate is much greater than that of the conventional activated sludge process. The active fraction of the biofilm is affected by the concentration of substrates in the bulk liquid, the actual metabolic rates within the biofilm, and the thickness of the biofilm. The suspended carrier configuration used in this investigation and the method of cultivating biofilm are beneficial for decreasing biofilm thickness, for increasing the activated biomass of nitrobacteria, and for increasing surface area of the biofilm relative to the volume of the reactors, which insulting in a high rate of nitrification. |
