Rotating Biological Contactors (RBCs)

What are rotating biological contactors (RBCs)?

Rotating biological contactors allow the wastewater to come in contact with a biological medium in order to remove pollutants in the wastewater before discharge of the treated wastewater to the environment.

What are rotating biological contactors (RBCs)?

The Rotating Biological Contactor (RBC) process is one of the most efficient fixed film wastewater treatment technologies.

The RBC Process

The process consists of large diameter steel or corrugated plastic media centered around a horizontal shaft, placed in a concrete tank.

The RBC Process

The RBC Process

The RBC Process

Biomass thickness ranges from 0.030 inch (0.75 mm) to 0.125 inch (3 mm) depending upon organic concentration, temperature and other process variables.

Benefits of the RBC process

• Consistent process results• Stable operation – frequent supervision

not required; microbial population accommodates organic and hydraulic fluctuations

• Lower expansion and retrofit costs – modular construction, reduced excavation costs

Benefits of the RBC process

• Smaller footprint – due to short wastewater retention time

• Minimal head loss through system• Very low energy consumption – on

the order of 3 kW per 3,000 people

Benefits of the RBC process

• Minimal maintenance – simple drive and bearing lubrication

• Reduced life cycle costs – as compared to suspended growth systems

• Simple operation – no recycle, less lab testing for process control

• Operator friendly

Applications of the RBC process

The RBC process is used in organic carbon removal (BOD), phosphorus removal, nitrification, denitrification, or various combinations.

Applications of the RBC process

• Municipal wastewater treatment• Food and beverage wastewater

treatment including meat packing, bakery, dairy, brewery

• Landfill leachate

Applications of the RBC process

• Refinery and petrochemical wastewater treatment

• Pulp and paper wastewater treatment

• Septage treatment• Many general industrial wastewaters

Applications of the RBC process

It can also be used in nitrification upgrades, retrofit applications, and in upgrading trickling filter plants.

RBC equipment

- available with a mechanical drive; with a mechanical drive and supplemental air; or with an air drive only.

- media is available as standard, medium or high density.

RBC equipment

Conventional low density media RBC

--25 feet long by 12 feet in diameter, --offers over 110,000 square feet of media

surface area

Conventional high density media RBC units--provide over 165,000 square feet of fixed

film surface.

RBC Process Design Considerations

• Substrate Removal Kinetics• Hydraulic Loading• Organic Loading• Wastewater Temperature

Table 1. Rotating Biological Contactors vs. Activated Sludge

Points of Comparison RBCs Activated Sludge

Process Stability

does not require recycling; not affected by clarifier

washouts or shock loadings

requires efficient solids settling and adequate bio-

solids recycling

Manpower Less manpower Relatively large manpower

Flexibility

easy to upgrade and expand; typically achieve excellent effluents without

additional control

difficult/costly expansions and upgrades;

troublesome low flow periods

Maintenance and Power Consumption

Power requirement is 25% of activated sludge power

requirement

Comparatively high power requirement

Ease of Nitrification

can achieve any degree of nitrification with only a single settling tank and without sludge recycle

require far more elaborate treatment stages

Sludge Characteristics Settles wellProne to settlement

problems

Advantages of rotating biological contactors

1. Short contact periods are required because of the large active surface

2. They are capable of handling a wide range of flows

3. Sloughed biomass generally has good settling characteristics and can easily be separated from waste stream

Advantages of rotating biological contactors

4. Operating costs are low because little skill is required in plant operation

5. Short retention time6. Low power requirements

Advantages of rotating biological contactors

7. Elimination of the channelling to which conventional percolators are susceptible

8. Low sludge production and excellent process control

Disadvantages of Rotating Biological Contactors

1. Requirement for covering RBC units in northern climates to protect against freezing

2. Shaft bearings and mechanical drive units require frequent maintenance

-End of Report-Thank You For Listening! =)

Prepared by:Alforque, Marian Joy B.Cabrera, AnacoritaLasheras, ChristianMiranda, Catherine Mae N.