ROTATING BIOLOGICAL CONTACTOR (RBC) PROCESS

1
ROTATING BIOLOGICAL CONTACTOR (RBC) PROCESS
Prepared By Michigan Department of Environmental
Quality Operator Training and Certification Unit
2
ROTATING BIOLOGICAL CONTACTORS
Contactors
Primary Treatment
Secondary Clarifier
Effluent
Influent
Solids Removal
3
RBC Secondary Treatment
Rotating
Plastic Media
Provides Large Surface Area
1.6 rpm
40 Submerged
Microorganisms Treat the Wastewater by Using
Organics
4
Wastewater
Slime Layer
Cell Membrane
Food Storage
Oxygen
Enzymes
(Absorption)
Adsorbed Particle
Soluble Organics
5
Oxygen
Organics
Liquid Film
Biomass
Media (disc)
Oxygen
6
Liquid Film
Liquid Film
Random Continuous Sloughing
OXYGEN
Organics
BIOMASS
Media
7
RBC Flow Scheme
INFLUENT
Primary Treatment
Rotating Biological Contactors
Pretreatment
Disinfection
Secondary Clarifiers
EFFLUENT
Solids Handling
8
ADVANTAGES OF RBC PROCESS
Simple Operation
Low Energy Requirements
Nitrification
Few Nuisances
Wide Flow Range
Large Biological Population
9
(No Transcript)
10
(No Transcript)
11
ADVANTAGES OF RBC PROCESS
Simple Operation
Low Energy Requirements
Nitrification
Few Nuisances
Wide Flow Range
Large Biological Population
Handles Shock Loads
Low Head Loss
12
DISADVANTAGES OF RBC PROCESS
Limited Controls
Enclosures
Limited Experience and Training
13
RBC COMPONENTS
CONTACTOR
TANK
CLARIFIER
14
RBC COMPONENTS
CONTACTOR
Discs
Shaft
Individual Disc
15
Media
High Density Polyethylene
Carbon Black
16
Media Irregular Surface
Maintain Spacing Increases Rigidity Increases
Surface Area Increases Contact Time
17
Media Irregular Surface
Corrugated
18
Media Irregular Surface
Dimpled
19
(No Transcript)
20
Random Fill
21
Media
1 Inch
BIOMASS
22
10 to 12 Ft Diameter
25 Ft Long
23
Media
High Density
Standard Density
1 inch
¾ inch
24
(No Transcript)
25
Shaft
Square Shaft
26
(No Transcript)
27
Round Shaft
28
Octagonal Shaft
29
(No Transcript)
30
Bearings
Floating Self-aligning
31
Bearings
32
Load Cells
33
Load Cells
Purpose Determine Weight of Contactor to
Determine Amount (Thickness) of Biomass
34
Drive Systems
- Chain
35
Drive Systems
- Direct
36
Drive Systems
- Air
Air Cups
Air Header
Air Diffusers
37
Drive Systems
- Air
Air Cups
Rotation
Air Header
38
Drive Systems
- Air
39
Drive Systems
- Air
40
Drive Systems
- Combination
41
Containment
42
Containment
Just Large Enough
Good Contact Minimal Short Circuiting Good Mixing
43
Train
FLOW
FLOW
RBC Systems Usually More Than One Contactor with
Flow Progressing in Series in a Train
44
Flow Schemes
Parallel to Shaft
Direction of Flow
Perpendicular to Shaft
Contactors May be Arranged With Flow Either
Parallel or Perpendicular to Shafts
45
Train
Small Systems Train May be One Contactor with
Separations and Baffles
46
Larger Systems Contactors are Set in Series in
Separate Tanks or in One Tank With
Enclosure
Effluent
Influent
Baffles
47
Baffles
48
Train
Baffles
FLOW
FLOW
Baffles Separate Each Contactor, Dividing the
Flow in the Train Into Separate Complete Mix
Zones of Treatment
49
Train
Baffles
FLOW
Each Zone of Treatment is Called a Stage
50
Train
Baffles
FLOW
51
2 Trains
Influent
5 Stages
1st Stage
Effluent
When a System Has More Than One Train, Each Zone
in the System That Receives the Same Loading is
Considered One Stage
52
STAGING
100
BOD, mg/L
60
39
25
18
Staging Results in Significantly More Efficient
Treatment
53
STAGING
BOD, mg/L
100 60 39
25 18 12 9
7
Stage 1 2
3 4
5 6
7
25 25 25 24
21 13 7
3
Ammonia Nitrogen, mg/L
This Especially Important for Facilities that are
Required Nitrify Ammonia
54
RBC Flow Scheme
INFLUENT
Primary Treatment
Rotating Biological Contactors
Pretreatment
Disinfection
Secondary Clarifiers
EFFLUENT
Solids Handling
55
Secondary Clarifier
Scum Removal
Influent
Effluent
Sludge Removal
56
Clarifier
500 to 800 gpd/sq.ft.
Chemical Phosphorus Removal
Sludge Removal
57
Enclosures
Protect Contactors
Ultraviolet Light
Hard Rains
Freezing
Algae
Equipment
Security
58
Enclosures
Types of Structures
Roof Only
Prefabricated Covers
Permanent Building
59
Enclosures
Prefabricated Covers
60
Enclosures
Permanent Building
61
Enclosures
Permanent Building
62
Enclosures
Operational Considerations
Ventilation
Humidity Control
Heat Loss
Observation
Maintenance
63
Basic Principles of Process
Contactors
Secondary Clarifier
Primary Treatment
Effluent
Influent
Solids Removal
64
(Calculation of Loading is Specific for Each
Type of Treatment Process)
65
RBC LOADINGS
HYDRAULIC
Liquid Volume - Applied to the Media surface
Use Plant Flow
- No Recirculation
Complete Available Surface Area
- from Manufacturer
Area is Not Calculated
66
RBC LOADINGS
HYDRAULIC
Liquid Volume - Applied to the Media surface
GALLONS PER DAY
PER
SQUARE FOOT
gpd / Ft2
67
RBC LOADINGS
HYDRAULIC
FORMULA
Flow Rate, gpd
Hydraulic Loading, gpd/ft2
Media Surface Area, ft2
EXAMPLE
Plant Flow 2.4 MGD Trains in Service 2 Contact
ors in Each Train 5 Baffles Between All
Contactors Each Contactor Surface Area 100,000
ft2 (from manufacturer) Primary Effluent Soluble
BOD 55 mg/L
68
Train
Baffles
FLOW
FLOW
5
Stages
(Zones of Treatment)
69
RBC LOADINGS
HYDRAULIC
FORMULA
Flow Rate, gpd
Hydraulic Loading, gpd/ft2
Media Surface Area, ft2
EXAMPLE
Plant Flow 2.4 MGD Trains in Service 2 Contact
ors in Each Train 5 Baffles Between All
Contactors Each Contactor Surface Area 100,000
ft2 (from manufacturer) Primary Effluent Soluble
BOD 55 mg/L
Total Surface Area
2 trains X 5 contactors/train X 100,000
ft2/contactor
1,000,000 ft2
70
RBC LOADINGS
HYDRAULIC
FORMULA
Flow Rate, gpd
Hydraulic Loading, gpd/ft2
Media Surface Area, ft2
X 1,000,000 gal/MG
2.4 MGD
Hydraulic Loading, gpd/ft2
1,000,000 ft2
2,400,000 gpd

1,000,000 ft2
2.4 gpd/ft2
71
RBC LOADINGS
ORGANIC
Organic Matter - BOD Applied to the Media
Surface
Soluble BOD
Media Surface Area (Not Volume)
Area in 1000 Ft2
72
RBC LOADINGS
ORGANIC
Organic Matter - Applied to the Media surface
per 1000 ft2
Pounds Soluble BOD per Day
Sol. BOD/Day/1000 ft2
73
RBC LOADINGS
ORGANIC
FORMULA
Organic Loading, Sol. BOD/Day/1000 ft2
Soluble BOD Applied, Sol. BOD/Day
Media Surface Area in 1000 ft2
74
RBC LOADINGS
ORGANIC
FORMULA
Soluble BOD Applied, Sol. BOD/Day
Organic Loading, Sol. BOD/Day/1000 ft2
Media Surface Area in 1000 ft2
EXAMPLE
Plant Flow 2.4 MGD Trains in Service 2 Contact
ors in Each Train 5 Baffles Between All
Contactors Each Contactor Surface Area 100,000
ft2 (from manufacturer) Primary Effluent Soluble
BOD 55 mg/L
Pounds Soluble BOD/Day
55 mg/L x 2.4 MGD x 8.34 /gal
1100 Sol. BOD/Day
75
RBC LOADINGS
ORGANIC
Total Surface Area ft2
Surface Area in 1000 ft2
1000
1,000,000 ft2
1,000 (1000 ft2)

1000
76
RBC LOADINGS
ORGANIC
FORMULA
Organic Loading, Sol. BOD/Day/1000 ft2
Soluble BOD applied, Sol. BOD/Day
Media Surface Area in 1000 ft2
1100 Sol. BOD/Day

Total System Org. Ld.
1,000 (1000 ft2)
1.1 Sol. BOD/Day/1000 ft2
77
RBC LOADINGS
FIRST STAGE ORGANIC
EXAMPLE
Plant Flow 2.4 MGD Trains in Service 2 Contact
ors in Each Train 4 Baffles Between All
Contactors Each Contactor Surface Area 100,000
ft2 (from manufacturer) Primary Effluent Soluble
BOD 55 mg/L
78
2 Trains
Influent
5 Stages
1st Stage
Effluent
When a System Has More Than One Train, Each Zone
in the System That Receives the Same Loading is
Considered One Stage
79
RBC LOADINGS
FIRST STAGE ORGANIC
First Stage Surface Area
2 contactors X 100,000 ft2/contactor
200,000 ft2
First Stage Surface Area in 1000 ft2
First Stage Surface Area ft2
1000
200,000 ft2
200 (1000 ft2)

1000
80
RBC LOADINGS
ORGANIC
FORMULA
Organic Loading, Sol. BOD/Day/1000 ft2
Soluble BOD applied, Sol. BOD/Day
Media Surface Area in 1000 ft2
1100 Sol. BOD/Day

First Stage Org. Ld.
200 (1000 ft2)
5.5 Sol. BOD/Day/1000 ft2
81
TYPICAL RBC LOADINGS
HYDRAULIC
CARBONACEOUS BOD REMOVAL
2 to 4 gpd/Ft2
NITRIFICATION
1.0 to 1.5 gpd/Ft2
82
TYPICAL RBC LOADINGS
Organic
(For Typical 30 mg/L Requirements)
All Media
2.0 Sol. BOD/DAY/1000 ft2
First Stage
2.5 to 4.0 Sol. BOD/DAY/ 1000 ft2
3.0 for mechanical drive EPA - caution over 2.5
83
ROTATING BIOLOGICAL CONTACTOR (RBC) PROCESS
Prepared By Michigan Department of Environmental
Quality Operator Training and Certification Unit