Sludge bulking

D. Jenkins, M. G. Richard, and G. T. Daigger, Manual on the Causes and Control of Activated Sludge Bulking and Foaming, Lewis Pubhshers, Boca Raton, Ela., 1993. 

Section 27.7 discloses the common causes of sludge rising and sludge bulking and discusses other possible alternatives for biological process optimization. 

Sludge bulking is another phenomenon that often occurs in activated sludge plants whereby the sludge occupies excessive volumes and will not settle rapidly. 

There are two principal types of sludge bulking problems (a) the growth of filamentous organisms and (b) the formation of swelling biological floes through the addition of bound water to the cells to the extent that their density is reduced. 

Possible causes of sludge bulking include (a) absence of certain necessary trace elements in wastewater (b) wide fluctuations in wastewater pH (c) limited DO in the aeration tank (d) inadequate FIM ratio (e) inadequate mean cell residence time Tc (f) inadequate return sludge pumping rate (g) internal plant overloading and (h) poor sedimentation clarifier operation. 

The problem of sludge bulking in the case of the activated sludge process can be controlled in the following ways ... 

Jenkins, D. The control of activated sludge bulking. 52nd Annual Conference, California Water Pollution Control Association, California, 1980. 

Leeuwen J van (1992) A review of the potential application of non-specific activated sludge bulking control, Water SA 18 101-105. 

Development of filamentous bacteria, as mentioned earlier, associated with sludge bulking. 

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