Approximately what percentage of surface area of a rotating biological contactor is immersed in wastewater?

A rotating biological contactor (RBC) is a type of biological treatment technology used in the treatment of wastewater. In this system, bacterial growth on a series of discs rotates partially submerged in the wastewater, allowing microorganisms to effectively treat the effluent.

The correct percentage of surface area that is typically immersed in wastewater during the operation of a rotating biological contactor is around 40%. This immersion level is crucial because it provides adequate contact between the microorganisms on the discs and the wastewater. It ensures that a large enough surface area is available for the bacteria to break down organic matter while still allowing enough air exposure for aerobic processes.

The operating principle behind the RBC involves both the portions of the discs submerged in the wastewater and those that are exposed to air (not submerged), as this alternating environment aids in the biofilm’s growth and ensures effective treatment. A lower percentage would not provide sufficient treatment, as the bacteria would have limited access to the wastewater, while a higher percentage could limit aeration and oxygen transfer essential for aerobic bacteria.