Denitrification in The Activated Sludge Process

Denitrification in the activated sludge process is the use of nitrate ions (NO3−) by facultative anaerobic (denitrifying) bacteria to degrade soluble carbonaceous BOD (cBOD). Although denitrification most often is observed in the secondary clarifier, denitrification occurs whenever an anoxic condition exists. Denitrification in the secondary clarifier often is referred to as “clumping,” “rising sludge,” and “dark sludge rising.” Clumping is highly undesired, because it results in poor compaction of solids, loss of solids, increased operational costs, and possible permit violations. Keywords: denitrification; activated sludge; facultative; anoxic; clumping