Cause Analysis and Control of Sludge Bulking in Sludge Shifting SBR Process

In the sludge shifting SBR process,sludge bulking occurred in the main reactor under the synergistic effects of long-term low organic load [0.1 to 0.2 kgCOD/(kgMLSS·d)] and long sludge age(20 d),and SVI was 303 mL/g.When increasing the sludge load to 0.4-1.3 kgCOD/(kgMLSS·d) in the main reactor,sludge bulking could not be controlled,the sludge settleability was deteriorated,SVI was increased to 330 mL/g,and sludge loss occurred.By changing the influent mode to static state,the main reactor could produce a relatively high concentration gradient of substrate in a short time,sludge bulking could be controlled,and the sludge settleability was recovered.