Culture and Application of Aerobic Denittrifying Granular Sludge on the Start-up of SBR-SND

To investigate the possibility of the rapidly starting of the SBR reactor, the start-up effect of aerobic granular sludge cultivated with and without nuclei were compared at low temperature. In the reactor which added aerobic denitrification biofilm debris as nuclei, aerobic granular formed after 30 days of operation at 20 degrees C, the average diameter of granular achieved 7.8mm, MLSS was above 12.275g/L, and SV30 was about 27%. Correspondingly, in the reactor without nuclei adding, after 60 days of operation at 20 degrees C, the average diameter of granular sludge reached 2mm, SV30 and MLSS changed from 65% and 7g/L to 24% and 11.042 g/L respectively. The results of this study indicated that the addition of nuclei can accelerate the granulation process and shorten the starting time of the granular sludge system. COD removal rate of the aerobic denitrifying sludge system with biofilm was also much higher than that without. The start-up effect of the reactor with nuclei addition was better than the reactor with no nuclei. Via the strategy of mix the nitrifying sludge which was originally cultured alone with the aerobic denitrifying granular sludge, the simultaneous nitrification-denitrification(SND) removal effect was studied. After 20 days of operation of the SBR-SND system, the average removal rate of TN was 85.25%, the average concentration of COD in effluent was 5.3mg/L, and the removal rate of COD was above 90% in the process. The system acquired an outstanding performance on simultaneous carbon and nitrogen removal.