Tennessee Wastewater Operator Practice Exam

What primary function do rotating biological contactors (RBCs) serve in wastewater treatment?

1. Promote sedimentation

2. Facilitate biological treatment

3. Enhance chemical reactions

4. Separate different wastewater phases

The correct answer is: Facilitate biological treatment

Rotating biological contactors (RBCs) play a crucial role in the biological treatment of wastewater. Their primary function is to provide a surface for microorganisms to grow and thrive, which facilitates the breakdown of organic matter present in the wastewater. As the RBCs rotate, the media (often made of plastic or similar materials) becomes alternately submerged in the incoming wastewater and exposed to air. This allows the biofilm of bacteria that forms on the media to efficiently consume organic pollutants during the submerged portion and to be aerated when exposed to air, enhancing the overall microbial activity. This process not only supports the biodegradation of contaminants but also helps in maintaining an effective environment for microbial growth. The RBC system capitalizes on the natural processes of aerobic and anaerobic digestion, resulting in the effective treatment of sewage and other wastewater types. In contrast, sedimentation is primarily a physical process for solids removal, while enhancing chemical reactions and separating different wastewater phases are not the main functions of RBCs. Thus, while other choices may be associated with wastewater treatment processes, they do not align with the specific design and operational purpose of rotating biological contactors.