Tennessee Wastewater Operator Practice Exam

What process is responsible for the removal of soluble Biochemical Oxygen Demand (BOD) in an RBC system?

1. Filtration

2. Chemical precipitation

3. Bio-flocculation

4. Activated carbon adsorption

The correct answer is: Bio-flocculation

In a Rotating Biological Contactor (RBC) system, the process that is responsible for the removal of soluble Biochemical Oxygen Demand (BOD) is bio-flocculation. This process involves the aggregation of microorganisms and fine particles into larger flocs, which enhances their ability to settle out of the wastewater. During bio-flocculation, bacteria naturally present in the RBC system adhere to the surface of the rotating discs and grow as a biofilm. This biofilm actively metabolizes organic matter, converting soluble BOD into microbial biomass as part of their metabolic processes. As the discs rotate and come into contact with the wastewater, these microorganisms utilize the soluble organic compounds, effectively removing BOD from the effluent. The larger flocs formed during this process can then be easily separated from the treated water during subsequent sedimentation processes. This efficiency not only helps to reduce the concentration of soluble BOD but also improves the overall efficiency of the wastewater treatment process. Other processes like filtration, chemical precipitation, and activated carbon adsorption play roles in wastewater treatment, but they do not primarily target the biological mechanisms that enable the effective removal of soluble BOD in the way that bio-flocculation does within an RBC system.