How do Rotating Biological Contactors spin?

Rotating Biological Contactors (RBCs) are designed to treat wastewater through a process that involves a series of rotating disks or media, which promote the growth of beneficial microorganisms. The correct method by which these disks spin is through a motor with a gear reducer or by air trapped in air cups.

In practice, the motor drives the rotation of the disks, allowing a portion of them to be submerged in wastewater and the remainder exposed to air. This rotation is critical because it ensures that the microorganisms attached to the media receive access to both the wastewater and oxygen, which is vital for their metabolic processes. The gear reducer is important because it allows the motor to operate efficiently at lower speeds, providing the proper rotational speed for effective treatment.

The other methods listed, such as gravity, a manual crank, and water pressure, do not provide the consistent and controlled means of rotation necessary for the biological treatment process. Gravity could influence some processes, but it would not be adequate for sustaining the controlled operation required in RBCs. A manual crank would not be practical for continuous operation in modern wastewater treatment facilities. Water pressure is not utilized in the rotation of the disks within an RBC, as the primary mechanism relies on the powered mechanical movement provided by the motor system.