How Does the RBC Process Work in Sewage Treatment Plants?

As municipalities seek efficient and cost-effective biological sewage treatment methods, the rotating biological contactor (RBC) process has emerged as a leading technology solution. Rotating biological contactor working in sewage treatment plants provide an innovative approach to removing organic matter and nutrients through their unique design.In this blog, we are going to learn what the process looks like.

The Rotating Biological Contactor Basics

At its core, the Rotating Biological Contactor system consists of a series of closely spaced circular discs mounted on a rotating shaft within a tank or trough. As the discs rotate, approximately 40% of their surface area is immersed in the incoming sewage flow.This constant rotation exposes the attached biomass on the disc surfaces to alternating cycles of feedstock from the wastewater and oxygen from the air. This creates an ideal environment for aerobic biological treatment to take place on the disc surfaces through oxidation and adsorption.

Rotating Biological Contactor Stages

Most RotatingBiological Contactorsystems utilize a multi-stage approach with separate tanks or zones for different levels of treatment:

First Stage: Focused on removal of organic matter or carbonaceous BOD through heterotrophic bacteria growth on the disc biofilms.

Second Stage: Designed for nitrification where autotrophic bacteria oxidize ammonium compounds into nitrites/nitrates. 

Third Stage: If required, enables denitrification where facultative bacteria convert nitrates into inert nitrogen gas.

Final Stage(s): Can incorporate polishing steps for final dissolved nutrient removal, disinfection, pH adjustment, etc.

This staging approach optimises each biofilm for its specific treatment process while minimizing interference between different bacterial groups.

Key Rotating Biological Contactor Design Factors

Several design parameters are crucial for effective RotatingBiological Contactorin sewage treatment plants:

Disc Configuration: Using properly sized discs spaced to maximize surface area while preventing biomass shearing. 

Rotational Speeds: Controlling rotational exposures balances feedstock replenishment with oxygen uptake.

Recirculation: Incorporating recycle streams enhances contact between biomass and wastewater.

Loading Rates: Calculating hydraulic and organic matter loadings rates sized for treatment capacity required.

Tank/Trough Design: Configured to evenly distribute flow across discs and vent gaseous byproducts.

With appropriate engineering, RotatingBiological Contactorsystems can reliably achieve >90% removal of BOD and ammonia compounds to meet discharge standards.

Advantages of Rotating Biological Contactor Sewage Treatment Plants

Compared to other aerobic treatment options like activated sludge, key RotatingBiological Contactor benefits include:

· Lower energy use from low-speed disc rotation vs. aeration

· Smaller footprint and simpler operation with no sludge recycle

· Easily expandable capacity by adding more disc units

· Process stability even with variable hydraulic/organic loads

· Lower excess sludge production and waste handling needs

RBC technology continues advancing with improved disc materials, supplemental aeration, anaerobic pretreatment integration, and AI-driven process controls.

Conclusion

As an attached growth aerobic system, the rotating biological contractor is a proven effective process for sewage treatment plants treating municipal wastewater. It is a simple yet innovative design that provides efficient pathways for removing organics, nutrients, and other contaminants before discharge.With a natural ability to handle fluctuating loads, lower costs, and process reliability, it's no surprise more sewage treatment plants have adopted RBC systems over recent decades. As engineering enhancements continue, theRotatingBiological Contactor is well-positioned to play an increasingly vital role in sustainable municipal wastewater treatment.

To explore customised commercial RO plants, Industrial RO plants, ETP or STP solutions for your needs in your areas and nearby regions, contact Netsol Water at:

Phone: +91-965-060-8473, Email: enquiry@netsolwater.com