Study On Aerobic Granular Sludge In The Mechanism And Stability Of Denitrification And Phosphorus Removal

The water pollution is mainly organic pollution and eutrophication, especially withnitrogen and phosphorus nutrients caused eutrophication. it has induced serious deteriorationto the quality of water environment. Phosphorus and nitrogen removal from wastewater hasbecome a hotspot to do the research on its new new theory and new technology.In the experiment, a sequencing batch reactor （SBR） was adopted to cultivate aerobicgranular sludge being simultaneous phosphorus and nitrogen removal. The selection ofculture conditions of anaerobic granular sludge; the characteristics of aerobic granular sludgeimpact test about nitrogen and phosphorus removal; the research and analysis about themechanism and stability of aerobic granular sludge being simultaneous nitrogen andphosphorus removal were mainly studied in this paper. The main results are as follows:（1） Aerobic granular sludge is cultured in sequencing batch reactor （SBR） with firstlydeveloping denitrification aerobic granular sludge then guiding phosphorus removal.Theaerobic granular sludge has a very compact and regular structure with a diameter of1.2to2.0mm and a clear outer shape，the Sludge Volumetric Index（SVI） and the Mixed LiquidSuspended Solid（MLSS） are as high as21.0ml/g and6446mg/L，respectively. The averageremoval rate of COD, ammonium，total inorganic nitrogen，phosphorus reaches90%，100%，90%and90%，respectively.（2） Two different methods of being cultivated aerobic granular sludge are compared, Themethod1: firstly developing phosphorus removal then guiding denitrification aerobic granularsludge and the method2: firstly developing denitrification aerobic granular sludge thenguiding phosphorus removal. The comparison results show that in the method2training timeis shorter and granular sludge being cultivated in physical and chemical characteristic,microbiology characteristics and the effect of denitrification and phosphorus removal are alittle better than in the method1.（3） Through the research different COD/NH₄⁺-N, founding that the inflow aboutCOD=300mg/L, COD/NH₄⁺-N=10, aerobic granular sludge of ammonia nitrogen andphosphorus removal efficiency is the best; Through study the anaerobic/aerobic time,founding that in anaerobic time about40min, aerobic time about200min, anaerobic granular sludge can finish ammonia nitrogen and phosphorus removal.（4） The study about the mechanism of granular sludge wiht denitrification andphosphorus removal show that, denitrification is finished by the simultaneous nitrification anddenitrifying process; phosphorus removal is done by oxygen uptaking phosphorus and anoxiauptaking phosphorus. The study about number contribution of denitrifying phosphorusbacteria show that, amounts of phosphorus-accumulating organisms （PAOs） capable ofdenitrification can be accumulated and enriched in the aerobic granular sludge coexisting withnitrifiers under appropriate operation conditions. The denitriyfing PAOs accounts for53%oftotal PAOs.（5） The study about the stability of mature aerobic granular sludge of simultaneousnitrogen and phosphorus removal, show that the effect of nitrogen and phosphorus removal isalmost same, through changing stirring intensity （shear stress） and the concentration ofCOD from the inflow in the SBR system. Only in the reactor stirring intensity adjusted to500r/min, COD to200mg/L, the effect of the phosphorus and nitrogen removal has smalldeclined. The reactor to keep60days in good of physical and chemical characters and goodeffect of denitrification and phosphorus removal can tell us that the effect of aerobic granularsludge for simultaneous nitrogen and phosphorus removal has good stability.