The Cultivation And Properties Research Of Aerobic Granular Sludge

It has become a hotspot to do the research on how to control the water bodies eutrophication caused by nitrogen and phosphorus, and how to remove efficiently the nitrogen and phosphorus as well as how to develop a special technics used for nitrogen and phosphorus removal, which are suitable to the situation of our country, economically and effectively. Aerobic granule is granular microbial self-aggregate cultivated in aerobic waste water treating system. Compared with conventional activated sludge system, the aerobic granule has strong and compact microbial structure, improved stability, the process of effluent separating is simple, the occupied area is small, the system can withstand the unfavorable hydraulic effect and toxic substances. Compared with anaerobic granules, the aerobic granules are more stable when used to treat the organic wastewater of low concentration, and the start-up period is much shorter than that of the anaerobic granules.Based on the latest research findings on aerobic granular sludge and biological nitrogen and phosphorus removal in both domestic and abroad, aerobic granular sludge had been cultivated with the normal activated sludge in SBAR system under the conditions of temperature 22 ℃, pH 7～8, aerobic reaction time 240min, DO 5～6mg/L. At steady operation, aerobic granules shows a very stable COD, NH₄⁺-N, phosphorus removal performance. The average removal rate for COD, ammonium and phosphorus reaches 95%, 95% and 60%, respectively at the influent concentration of COD 1000 mg/L, NH₄⁺-N 100mg/L and phosphorus 15mg/L. Significant amounts of phosphorus-accumulating organisms capable of denitrification can be accumulated and enriched in the aerobic granular sludge coexsting with nitrifiers under appropriate operational conditions. What is more important, the denitrifying PAOs take up and store phosphate using nitrate as electron acceptor, then the organic carbon substrate can be used simultaneously for both phosphorus and nitrogen removal.After successfully cultivating aerobic granular sludge, the parameters affecting nitrogen and phosphorus removal were studied through adapting the operational conditions of SBAR. The cultivated aerobic granular sludge were sieved to three groups 0.5～1.0mm, 1.0～1.5mm and above 1.5mm .The properties and removal efficiency of each group were observed. Results showed that the COD and NH₄⁺-N removals were more than 90%, while the TN removal varied diversely, group 1.0～1.5mm was prior to others. According to the nitrification and denitrification rate test, groups 1.0～1.5mm and above 1.5mm had inhibiting effect on denitrification. The bigger aerobic granule size the worse the denitrification extent. Mixed...