[Rapid cultivation of aerobic nitrifying granular sludge with alternate loading method]

The nitrifying granular sludge was cultivated in three Sequencing Batch Reactors (SBR), R1, R2 and R3, respectively. There were two new cultivating methods applied in R1 and R2, which alternately changed the influent nitrogen loading and the influent carbon and nitrogen loading, respectively. The traditional method of step-increasing nitrogen loading was adopted in R3. The results showed that the full-sense nitrifying granular sludge could be cultivated successfully after 70 days in R1 and R2, while it took 147 days in R3. The denser granules with higher activity of nitrifying bacteria and better denitrifying performance could be rapidly obtained by alternately changing the influent carbon and nitrogen loading simultaneously. The removal rates of ammonia nitrogen and total nitrogen were about 95% and 70%, respectively, under the stable operation conditions. Overall, the physical and chemical properties of granules and the performance of denitrification were outstanding in R2. From the comparison results, it indicates that the increasing influent organic loading can speed up the formation of granules and their growth at the early cultivation stage.