What is the minimum dissolved oxygen level required in an aeration tank for biological nitrification?

The minimum dissolved oxygen level required in an aeration tank for biological nitrification is 1 ppm. Biological nitrification is a crucial process in wastewater treatment, where ammonia is oxidized to nitrite and then to nitrate by nitrifying bacteria. For these bacteria to function efficiently, they require an adequate dissolved oxygen concentration.

In general, nitrifying bacteria are more sensitive to low oxygen levels than heterotrophic bacteria. A minimum of 1 ppm of dissolved oxygen ensures that the nitrifying bacteria can effectively carry out the oxidation process. Levels below this threshold may not support optimal growth and activity of the nitrifying organisms, leading to incomplete nitrification and potential issues with ammonia accumulation in the treated effluent.

Maintaining dissolved oxygen levels above this threshold is critical for achieving regulatory compliance and ensuring the effective treatment of wastewater. That's why a level of 1 ppm is considered the minimum requirement.