RBC Equipment and Systems
RBC Design Considerations2>
Unit Sizing
Organic loading is the primary design parameter for the RBC process. This is generally expressed as the organic loading per unit of media surface area per unit of time, or in units of pounds BOD5 per thousand square feet per day. Wastewater temperatures above 55 degrees F have minimal affect on organic removal and nitrification rates; however, below 55 degrees F, manufacturers shall be contacted by the designer to obtain the various correction factors that must be utilized to determine the needed additional media surface area.
To define RBC design loading rates, use the following parameters:
- Total influent BOD5 concentration
- Soluble influent BOD5 concentration
- Percentage of total and soluble BOD5 to be removed
- Wastewater temperature
- Primary effluent dissolved oxygen
- Media arrangement, number of stages and surface area of media in each stage
- Rotational velocity of the media
- Retention time within the RBC tank(s)
- Influent soluble BOD5 to the RBC system
- Influent hydrogen sulfide concentrations
- Peak loading, BOD5 max/BOD5 avg.; TKN max/TKN avg
Loading Rates
Staging Units
- Design safety factors
- Secondary clarification
Plant Design Considerations
- Enclosures
- Flexibility and Flow Control
- Monitoring
- Contactor Basins and Channels
- Drains
- Clearance
- Basin depth for submergence
- Basin volume-to-media surface area
- Channel aeration/configurations for scouring velocity
- Side wall slope
Equipment Considerations
- Shafts
- Media
- Drive Systems
- Bearings
- Load Cells (Hydraulic or Electronic)
Other Considerations
- Protection from direct sunlight or temperatures above 95 F
- Monitoring Schedules: reading load cells, visual inspections of biofilm growth, media integrity, status of mechanical and structural components.
- Safety Features: lighting, handrails, drive mechanism enclosures, walkways, desk gratings, slip-resistant surfaces
- Monitoring equipment or devices: stop motion detectors, RPM indicators, Clamp-on ammeters