Culture and Phosphorus Removal Property of Granular Sludge for Denitrifying Phosphorus Removal

The granular sludge for denitrifying phosphorus removal is successfully formed in a sequencing batch reactor(SBR) fed with synthetic wastewater,by controlling the operational modes of anaerobic/anoxic/aerobic,anoxic addition of the nitrate,and selection pressure.The granular sludge turns into a shape with a diameter of 0.3 to 0.5 mm,and sludge volume index(SVI) and mixed liquid suspended solid(MLSS) are maintained at 45 mL/g and 4 000 mg/L,respectively,during the steady operation.The granular sludge for the denitrifying phosphorus removal also shows a good nutrient removal capability,with the COD,ammonia nitrogen and phosphorus removal efficiencies of 88%,96% and 90%,respectively.The fate of phosphorus and the X-ray diffraction test results suggest the existence of granular sludge phosphate precipitation phosphorus removal phenomena.Granular sludge for the denitrifying phosphorus removal in the experiment uses biological phosphorus removal,and it also has phosphorus removal through phosphate precipitation in granular sludge.