Florida Wastewater Practice Test

How is organic loading calculated for an RBC unit?

1. Organic loading is a constant

2. Dividing surface area by flow rate

3. Based on solids concentration and flow

4. Adding total BOD and dividing by volume

The correct answer is: Based on solids concentration and flow

Organic loading for a rotating biological contactor (RBC) unit is calculated based on the solids concentration in the influent and the flow rate. This calculation considers the amount of biodegradable material present in the wastewater, typically expressed as biochemical oxygen demand (BOD). By assessing both the concentration of BOD and the flow rate, operators can determine the overall organic load that the RBC unit must process. Understanding organic loading is crucial because it directly impacts the performance and efficiency of the treatment system. A higher organic loading indicates a greater demand for microbial activity within the RBC, which features attached growth media that microorganisms use to degrade organic matter. Calculating organic loading using solids concentration and flow helps in designing the RBC system appropriately to ensure it can handle the expected loads while meeting effluent quality standards. This method reflects the actual conditions under which the RBC operates, rather than focusing solely on physical dimensions or averages that may not account for variations in wastewater characteristics. The other options do not accurately reflect the method of calculating organic loading for an RBC unit. A constant value does not represent the variability seen in wastewater treatment, while dividing surface area by flow rate does not account for the concentration of organics. Lastly, adding total BOD and dividing by volume oversimplifies the relationship