Characteristics Of Denitrification And Phosphorus Removal In SBR With Granular Sludges

Compared with traditional active sludge, the granular sludge was paid more and more attention by its good settling ability and high activity. Denitrification and EBPR in three SBRs were carried in this experiment, and through the control of mixing speed and substrate, the granular sludge with stable performance was cultivated, and it had good removal rate of nitrogen and phosphorus. Synthetic wastewater was used , and the characteristics of the granular sludge cultivated in SBR were studied. The conclusions as follows:(1) Anoxic and EBPR granular sludge with good settling ability and high removal rate of nitrogen and phosphorus can be cultivated in SBR.(2) The rotation had great influence on the article size and activeness of anoxic granular sludge. With higher speed of rotation, the anoxic granular sludge had higher VSS/SS and bigger article size, and with lower speed, it had lower VSS/SS and smaller article size.(3) The degree of denitrification was responded accuratly by the change of ORP and pH. And the end point of denitrification reaction may accurately judged by the change curve.(4) C/N was an important factor in the removal rate of nitrogen and COD, and only by suitable C/N, the nitrogen and COD can both have a better removal rate.(5) The VSS/SS of biological phosphorus granular sludge is above 75%, and the sludge has a good activeness.(6) Under the steady state(COD=350mg/L, P=10mg/L, NH₄⁺-N=10mg/L,SRT 20 days) in EBPR systerm,the greatest release speed of phosphorus was 23.2mgP/gSS·h, and the greatest absorption speed of phosphorus was 11.6mgP/gSS·h.(7) SEM observation indicated that, the mature anoxic granular sludge's surface was composed by the laminated shape of biomembrane which had a even distribution,and inorganic crystal nucleus and filament bacteria was observed inside the granular sludge. Obviously, the anoxic granular sludge raised in this experiment took the inorganic crystal nucleus as a core, and filament bacteria as skeleton pellet. In EBPR systerm, different microorganism distributioned randomly inside the granular sludge, and laminational distribution didn't exit.