| The laboratory-scale study was carried out on cultivation of aerobic granular sludge with the selection pressure theory via decreasing settling time in continuous-flow completely stirred tank reactor and sequencing batch reactor, respectively. The cultivation and operational performance of aerobic granular sludge were investigated in CSTR under the condition of different influent patterns and carbon sources; the cultivation and operational performance of aerobic granular sludge were investigated in SBR with domestic wastewater.The results showed that aerobic granular sludge can be cultivated respectively in CSTR with different influent patterns and influent carbon sources. The ball-shape, ellipsoidal-shape and golden-color aerobic granular sludge of 3.0～5.0mm in diameter and 30～58m/h in settling velocity were formed with acetic sodium as the carbon source and variable flow as influent pattern under ambient temperature when volumetric organic loading rate was 2.0kgCODcr·m-3·d-1 and settling time was 1h; grey-golden-color, fluffy aerobic granular sludge of 0.5～3.0mm in diameter were formed with domestic wastewater as the carbon source and constant flow as influent pattern under 25℃when volumetric organic loading rate was 3.0kgCODcr·m-3·d-1 and settling time was 1h, and granulation of aerobic granular sludge were observed; aerobic granular sludge can be formed with both variable and constant influent pattern under 25℃with carbon source of acetic sodium when volumetric organic loading rate was 1.0kgCODcr·m-3·d-1, settling time was 2h and carbon source of domestic wastewater when volumetric organic loading rate was 3.0kgCODcr·m-3·d-1 and settling time was 1.5h.The results also showed that the shape of aerobic granular sludge formed in reactors with different influent patterns was similar, smooth granule of 1.0～3.0mm in diameter were formed with acetic sodium as the carbon source. Granule cultivated with influent pattern of variable flow appeared early; fluffy granule with abundant ball-shape granule of 1.0～3.0mm in diameter were formed with domestic wastewater as the carbon source, and granule cultivated with constant flow were more fluffy.The results of operational performance of CSTR showed that the removal of 85%,80%,90% for CODcr,PO43-,NH4+-N respectively were obtained with acetic sodium as the carbon source and variable flow as influent pattern under ambient temperature; the removal of 90%,80%,90%,70% for CODcr,TP,NH4+-N,TN respectively were obtained with acetic sodium as the carbon source and constant flow as influent pattern under 25℃(with constant settling time of 1h), the removal of 87%,60%,55%,60% for CODcr,TP,NH4+-N,TN respectively were obtained with domestic wastewater as the carbon source and constant flow as influent pattern under 25℃(with constant settling time of 1h), the operational performance results of granulation reactor with domestic wastewater showed that low removal of NH4+-N and TN were obtained, and the removal of 87% and 65% for CODcr and TP respectively were obtained with constant flow as influent pattern under 25℃; the removal of 90%,80%,97%,70% for CODcr,TP,NH4+-N,TN respectively were obtained with acetic sodium as the carbon source and constant flow as influent pattern under 25℃(with decreasing of settling time), the removal of 90%,55%,80%,80% for CODcr,TP,NH4+-N,TN respectively were obtained with domestic wastewater as the carbon source and constant flow as influent pattern under 25℃(with decreasing of settling time); the removal of 90%,80%,95%,75% for CODcr,TP,NH4+-N,TN respectively were obtained with acetic sodium as the carbon source and variable flow as influent pattern under 25℃, the removal of 90%,55%,90%,75% for CODcr,TP,NH4+-N,TN respectively were obtained with domestic wastewater as the carbon source and variable flow as influent pattern under 25℃.It was found that reactor with granule was start-up quickly; aerobic granular sludge cultivated in CSTR were unstable; aerobic granular sludge cultivated with domestic wastewater can stay longer; granule with core, fluffy surface were formed without the control of temperature.The observation results of naked eyes, optical bio-microscope and SEM showed that the granulation was accomplished via such consecutive processes as EPS self-flocculation, filamentous binding and attachment among the small-sized granules, and four steps including inner nucleus formation and flocculation, granule formation and maturation were found during the aerobic sludge granulation. The results also showed that obvious layered structure were conducted in granule, with food net formed by different microbes, besides abundant filamentous bacteria and ciliary protozoa on the surface, long and short bacilus were also observed in the granule.The results of operational performance of aerobic granular sludge in CSTR showed that aerobic granular sludge play an important role in the removal of nitrogen and phosphorus, and operational stable of the reactor; high and stable removal and SND can be obtained in the reactor; aerobic granulation and stable and efficient operation can be obtained by the method of increasing influent organic concentration to increase the organic loading rate.The results also showed that CODcr removal profile decreased when the settling time decreased; high operational performance can be obtained when the settling time was 2h; for the reactor with variable flow as influent pattern, the removal profile of CODcr and organic loading rate of CODcr were higher than the reactor with constant flow as influent pattern, otherwise, the removal profile of NH4+-N and TN were lower. The removal profile of volumetric organic loading rate increased with increasing of volumetric organic loading rate; the highest removal profile of CODcr,TP,NH4+-N can be obtained when volumetric organic loading rate was 1.5kgCODcr·m-3·d-1; more efficient performance can be obtained by the reactor with variable flow as influent pattern.Gey, fluffy structure granular sludge of 2～10mm in diameter were formed in SBR with domestic wastewater as influent under ambient temperature, and granulation can be obtained. The optical bio-microscope observation showed that abundant Vorticella and filamentous bacteria were around the granular surface. The operational performance was decided by the aeration time.
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