What is a consequence of denitrification in wastewater treatment?

Denitrification in wastewater treatment is a microbial process where nitrates and nitrites are reduced to nitrogen gas, which is then released into the atmosphere. This process is crucial for nitrogen removal in treatment systems, particularly in reducing the harmful effects of excess nitrogen in receiving water bodies.

When denitrification occurs, especially under conditions where there is insufficient oxygen (anoxic conditions), it can lead to a phenomenon known as rising sludge. This happens because the gas produced during denitrification—typically nitrogen gas—can become trapped in the sludge, causing it to become less dense and potentially float. This floating sludge, or rising sludge, can lead to operational difficulties in a treatment plant, such as reduced treatment efficiency and problems with solids removal.

In contrast, options like straggler floc, methane production, and low MLSS do not directly pertain to denitrification. Straggler floc refers to poorly settling particles in activated sludge systems, while methane production is a result of anaerobic digestion processes rather than denitrification. Low MLSS refers to low mixed liquor suspended solids concentrations, which can occur for various reasons but is not a direct consequence of the denitrification process itself.