Filamentous Bulking and Recovery in Biological Phosphorus Removal Granular Sludge System

The stability of granular sludge is an important factor influencing its widespread use in wastewater treatment.The influence of filamentous bulking on the biological phosphorus removal capability and stability of granular sludge in SBR was discussed.The 396-day operation result shows that the presence of filamentous bacteria plays an important role in formation and stabilization of granular sludge.During the overgrowth of filamentous bacteria,the phosphorus removal rate and the maximum phosphorus release rate of granular sludge decrease to less than 60% and 26.67 mgP/(gMLVSS·h)respectively,and the effluent SS and SVI increase to more than 100 mg/L and 50 mL/g respectively.The filamentous bulking system can be recovered by any one of extending sedimentation time,increasing stirring speed and adding non-filamentous bulking granular sludge,and the required recovery time is 53,26 and 20 days respectively.