Viscous bulking caused by change in wastewater composition and its control
进水水质成分改变引发的污泥粘性膨胀及控制

The appearance of sludge bulking in a lab-scale activated sludge plant with enhanced SBR process was described. Deterioration of SVI was observed after the change of composition of domestic wastewater by addition of starchy. The sludge had a jelly-like viscous consistency with a great amount of exocellular slime. Microscopic examinations showed that a kind of finger-like zoogloeal had excessive growth, the number of filamentous microorganisms significantly dropped. The results showed that the bulking was a very rarely observed viscous bulking. Viscous bulking was not effectively controlled by stopping adding starchy and increasing DO concentration, but the slime disappeared gradually. After slime disappeared, the viscous bulking was restricted by simulating earlier wastewater composition and reducing SRT. The sludge settleability recovered in a short time. Furthermore, the degrading pollutants capability of system was analyzed during the viscous bulking.