| Aerobic granular sludge has become the research hotspot of biological wastewater treatment. Despite the intensive research, the mechanisms responsible for aerobic granulation have not yet been clearly described. In order to investigate the effect of different seed sludge on the aerobic sludge granulation, sludge which is different sources and characteristics was used as seed sludge in SBR and continuous-flow systems.The conclusions derived from the investigation are as follows:in the SBR system, three kinds of floc sludge which were taken from industrial park sewage treatment plant, urban sewage treatment plant, and laboratory aerobic granular sludge reactor were used as seed sludge in three reactors. After50days of operation, aerobic granular sludge which is similar to each other were successfully formed in all of the three reactors, SVI were up to48mL/g,43mL/g, and46mL/g, respectively. The average particle diameter was0.43mm,0.42mm, and0.40mm, respectively. Furthermore, granules were firstly found in the reactor seeded sludge from industrial park sewage treatment plant. In the up-flow continuous-flow system, after12days of incubation, granulation did not occurred due to sludge bulking in both reactors. Some small granules appeared temporarily in the reactor seeded sludge from industrial park sewage treatment plant.This study proposes that if reactor inoculates sludge which contains a large number of particulate matters such as inorganic or inert carriers, the formation of aerobic granular sludge can be accelerated. There was no classic "filamentous framework hypothesis" for the granulation since no filamentous bacteria in the structure of granules. Filamentous bacteria are not the necessary condition for the formation of granular sludge; raw water characteristic and operational mechanism are still the main factors which affect the formation of aerobic granular sludge. |
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