Sludge bulking

Sludge bulking is defined as poor settling characteristics in sedimentation tanks. It is a problem that occurs in activated sludge process in wastewater treatment. The main cause of sludge bulking is the growth filamentous bacteria and algae.

Filamentous microorganisms grow in long strands that act to clog up the waste treatment system. When favourable growing conditions conditions are satisfied filamentous organisms predominate and with their high surfaces area they use most of the oxygen in the tank and form a hard and low settleable sludge.

To avoid sludge bulking some of the flow that enters the reactor can be by-passed, recycle ratio can be increased, lime or soda can be added to the reactor or the re-aeration rate increased.

ee also

*Anaerobic digestion