Questions about a claim regarding denitrification
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If the dissolved oxygen in the activated sludge mixture exiting the aeration tank is below 0.5, and the carbon-nitrogen ratio is severely unbalanced, the activated sludge remaining in the secondary sedimentation tank will float to the surface. Well, I can understand how a low dissolved oxygen level of 0.5 could lead to denitrification, but how can the severe imbalance in the carbon-nitrogen ratio be explained?
Denitrifying bacteria require a carbon source to carry out denitrification; in other words, if the BOD of the effluent is very low, denitrification is unlikely to occur even if the dissolved oxygen level is low.