| To solve low efficiency of nitrogen removal and sludge upflowing in single activated sludge system, it was suggested that Sequencing Batch Reactor (SBR) could be applied in dual activated sludge system.So the objective of this paper was to study the related character of SBR under anoxic environment and to culture granulated sludge.Through comparing two carbon source, first, it was proved sodium acetate is better than glucose. Therefore sodium acetate was adopted as carbon source.Based on these results, the effect of the concentration of calcium ion on the stability of the granulated sludge and biological tissue and activity of the granulated was then studied. The results indicated that:(1) Under mechanical mixing conditions(50p/min), HRT 6h, temperature25 C, a high biomass concentration in SBR was obtained in short period with volumertric loading rates of 0.66kgNO3-- N/m3.d and sludge loading rates of 0.153 kgNO3- -N/kgVss.d and efficiency of nitrogen removal was above 95%.So,SBR is an ideal reactor for nitrogen removal.(2) Calcium ion can promote granulation process in this SBR. When the concentration of calcium ion was about 300mg/L, plenty of granular sludge was obtained. The microbiology of anoxic granules has also then been examined.The picture showed the granules were mainly made up of cocci and bacillus and no filamentrous bacterium was found during experiment. Finally, the test indicated that the activity of granular sludge was lower than that of flocculent sludge.( 3 ) Whether the concentrion of calcium ion in substrate was high or low,the anoxic sludge of SBR would upfloat after a period of stable operation and then washed out. The result exhibited that adding calcium ion into substrate couldn't uproot the upfloat of anoxic sludge. Therefore, other measure may be considered to solve this problem.
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