Sludge bulking occurs when the sludge fails to separate out in the sedimentation tanks. The main cause of sludge bulking is the growth of filamentous bacteria. Filamentous microorganisms grow in long strands that have much greater volume and surface area than conventional floc and are very slow to settle.
To remove the above ..
Analyse the bacteria Generally Filamentous bacteria are the most common cause of sludge bulking.
The F/M rate (food to microorganism) is a control number for determining the proper number of microorganisms for the system.
Chlorine and hydrogen peroxide can control the filaments
Excessive filamentous development is often caused not only by environmental conditions but also by the influent itself which may contain food for bacteria.
Microscopic examination determines which type of filamentous bacteria is present and determines the treatment that should be applied.
It is absolutely critical that you first identify the cause of the bulking, then, and only then, can you set a course to address the problem. Otherwise you (and us) are only guessing.
All of these answers may work. Experience shows that SBR is more difficult to control than conventional aeration and settlement once it has got out of control. It also depends on whether the tanks are open or enclosed.
Same way as any bulking problem. First identify the cause (usually assisted by doing some checks on dominant bacteria) - DO too low? Do too high? SRT too low? SRT too high? Nutrient limitations? Would you benefit from an anoxic fill? Aerobic fill?