Jozef KRIŠ of Secondary clarIfIerS Research field: water ...
CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and...
Transcript of CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and...
CLARIFIERSCLARIFIERS
Prepared ByMichigan Department of Environmental Quality
Operator Training and Certification Unit
Provide Quiescent Area
Separation of Solids
FloatableSettleable
ClarifiersSedimentation Basins
Settling Tanks
CLARIFIERSCLARIFIERS
Clarifiers
Efficiency of Solids Removal Related To:
1. Characteristics of the Solids
2. Characteristics of the Water
3. Characteristics of the Clarifier
StokeStoke’’s Laws Law
2(p - po)g 9n
(d/2)2VF =
VF = Fall Velocity(p - po) = Density difference between
particle and watern = viscosity of waterg = gravitational acceleration constantd = diameter of the particle
StokeStoke’’s Laws Law
VF = Fall Velocity(p - po) = Density difference between
particle and watern = viscosity of waterg = gravitational acceleration constantd = diameter of the particle
Forget the FormulaForget the FormulaRemember the Removal Remember the Removal
Efficiency Depends on Several Efficiency Depends on Several FactorsFactors
Particle Size versus Settling Time
Particle Sizemm Order of Size Time to Settle
1.0 Coarse Sand 3 Seconds
0.1 Fine Sand 38 Seconds
0.01 Silt 33 Minutes
0.001 Bacteria 55 Hours
0.0001 Colloidal 230 Days
0.00001 Colloidal 6.3 Years
Clarifiers
Efficiency of Solids Removal Related To:
1. Characteristics of the Solids
2. Characteristics of the Water
3. Characteristics of the Clarifier
StokeStoke’’s Laws Law
VF = Fall Velocity(p - po) = Density difference between
particle and watern = viscosity of waterg = gravitational acceleration constantd = diameter of the particle
Forget the FormulaForget the FormulaRemember the Removal Remember the Removal
Efficiency Depends on Several Efficiency Depends on Several FactorsFactors
Warm WaterLess DenseLess Viscous
Solids Settle More Readily in Warm WaterThan in Cold Water
Cold Water More Dense
More Viscous
Warm Water - Greater Efficiency of Clarification
Settling RateSettling Rate
Cool Water- Less Efficiency of Clarification
Clarifiers
Efficiency of Solids Removal Related To:
1. Characteristics of the Solids
2. Characteristics of the Water
3. Characteristics of the Clarifier
Clarifiers
Efficiency of Solids Removal Related To:
3. Characteristics of the ClarifierSurface Area
DepthHydraulic Loading
Solids Loading
Clarifiers
Efficiency of Solids Removal Related To:
3. Characteristics of the ClarifierSurface Area
DepthHydraulic Loading
Solids LoadingDesign
OperationMaintenance
Clarifiers
Efficiency of Solids Removal Related To:
3. Characteristics of the Clarifier
Flow Characteristics in the Clarifier
Flow Must be Dispersed Evenly Throughout
Higher Flow (Horizontal Velocity) in One Part of Tank
(Detention Time vs. Fall Velocity)
Density Currents
Currents Within the Tank Carry Solids Through the Tank.
Not the Same as Excessive Hydraulic Load
Clarifier Short CircuitingClarifier Short Circuiting
Clarifier Short CircuitingClarifier Short Circuiting
Missing or poor influent baffling
Causes
Clarifier Short CircuitingClarifier Short Circuiting
Missing or poor influent baffling
Causes
Clarifier Short CircuitingClarifier Short Circuiting
Missing or poor influent baffling
Causes
Clarifier Short CircuitingClarifier Short Circuiting
Uneven effluent weirs
Plant growth or thrash in effluent weirs
Causes
Clarifier Short CircuitingClarifier Short Circuiting
Temperature stratification between influent & clarifier water temperatures.
Causes
Clarifier Short CircuitingClarifier Short Circuiting
Monitoring for Short Circuiting
Visual Observation
Flow Over Weir
Solids Over Weir
Clarifier Short CircuitingClarifier Short Circuiting
Monitoring for Short Circuiting
Dye Testing
Higher Flow (Horizontal Velocity) in One Part of TankDensity Currents
Clarifier Short CircuitingClarifier Short Circuiting
Clarifier Short CircuitingClarifier Short Circuiting
• Missing or poor influent baffling
• Uneven effluent weirs
• Plant growth or thrash in effluent weirs
• Temperature stratification between influent & clarifier water temperatures.
Causes
Clarifiers
Efficiency of Solids Removal Related To:
1. Characteristics of the Solids
2. Characteristics of the Water
3. Characteristics of the Clarifier
Clarifiers
Types of ClarifiersTypes of ClarifiersInclined Plate
(Lamella)
Rectangular
Circular
Inclined Plate(Lamella)
Overflow Box
Clarifier Influent
Sludge Discharge
Clarifier Effluent
SludgeHopper
Flocculation Tank
FlashMix Tank
Coagulant Feed
Feed BoxDischarge FlumesDistribution Orifice
Inclined Plates
Types of ClarifiersTypes of Clarifiers – – Inclined Plate (Lamella)Inclined Plate (Lamella)
Types of ClarifiersTypes of Clarifiers – – Inclined Plate (Lamella)Inclined Plate (Lamella)
Increased settling efficiency due to increased surface area
Smaller Area Needed for Installation
Types of ClarifiersTypes of Clarifiers – – Inclined Plate (Lamella)Inclined Plate (Lamella)
Increased settling efficiency due to increased surface area
Smaller Area Needed for Installation
Types of ClarifiersTypes of Clarifiers – – Inclined Plate (Lamella)Inclined Plate (Lamella)
Seldom Used With Organic WastesBiological Growths Reduce Efficiency
Mostly Industrial Applications
Types of ClarifiersTypes of Clarifiers – – Inclined Plate (Lamella)Inclined Plate (Lamella)
Rectangular Clarifiers
EffluentLaunder
EffluentWeir
ScumTrough
Flights
DriveUnit
DriveChain
DriveGear
IdlerSprockets
Sludge Withdrawal
Pipe
SludgeTrough
InletBaffleInlet
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
InletBaffleInlet
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Influent baffling
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
FloatableSettleable
EffluentLaunder
EffluentWeir
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Effluent
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
FloatableSettleable
Rails
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Solids Removal Mechanism
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
DriveChain
DriveUnit
DriveGear
IdlerSprockets
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Flights
Rails
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Flights
Wear Shoes Rails
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Wear Shoes Rails
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Prevent Wear on the Flights Where They Contact the Rails
Transfer Wear to the Shoe Instead of the Flights
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Flights
Sludge
Sludge Withdrawal
Pipe
SludgeTrough
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Flights
Scum
Scum RemovalScum
Trough
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Scum Removal
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Scum Removal
EffluentLaunder
EffluentWeir
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Effluent
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Effluent Weir – “V Notch”
Flow = Velocity X Area
As Flow Increases, Area Increases
And As Area Increases, Velocity Decreases
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Flow = Velocity X Area
Effluent Weir – “V Notch”
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Effluent Weir – “V Notch”
Helps Keep Velocity Constant
Reduces Solids Build-up Behind Weir
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Single Weir
Finger Weirs
Effluent Weirs
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Effluent Weirs
EffluentLaunder
EffluentWeir
ScumTrough
Flights
DriveUnit
DriveChain
DriveGear
IdlerSprockets
Sludge Withdrawal
Pipe
SludgeTrough
InletBaffleInlet
Types of ClarifiersTypes of Clarifiers – – RectangularRectangular
Monitor for Short Circuiting
Visual Observation
Flow Over Weir
Solids Over Weir
Dye Testing
Secondary Rectangular Clarifiers – Most Important
Consider Baffles
Circular Clarifiers
Circular ClarifierCircular Clarifier
Circular ClarifierCircular Clarifier
Influent typically enters the basin from the center rather than from one end.
Circular ClarifierCircular Clarifier
Influent
Influent typically enters the basin from the center rather than from one end.
Circular ClarifierCircular Clarifier
Influent
A Circular Baffle Directs Flow
Center Baffle
Circular ClarifierCircular Clarifier
A Circular Baffle Directs Flow
Circular ClarifierCircular Clarifier
Influent
Solids Settle
Scraped to Sump
Removed by Pumping Center Baffle
Sludge Sump
Sludge Plow
Circular ClarifierCircular ClarifierSolids Settle
Scraped to Sump
Removed by Pumping
Circular ClarifierCircular ClarifierSolids Settle
Scraped to Sump
Removed by Pumping
Circular ClarifierCircular Clarifier
Influent
Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum
Drive UnitSkimmer Arm
ScumBaffle
Circular ClarifierCircular Clarifier
Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum
Circular ClarifierCircular Clarifier
Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum
Circular ClarifierCircular Clarifier
Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum
Circular ClarifierCircular Clarifier
Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum
Circular ClarifierCircular Clarifier
Influent
The Water Flows to the Effluent Weir Around the Circumference of the Clarifier
Center Baffle Effluent Weir
Sludge Sump
Sludge Plow
Circular Clarifier Outlet
Effluent
EffluentLaunder
EffluentWeir
ScumBaffle
1 2 3OuterWall
InnerWall
SuspendedIn Clarifier
The Launder and Weir May Be
Effluent Launder/Weir Inside Clarifier (#2)Can Create Water Current
• Loss of solids over weir.
• Baffles used to redirect & slow water currents.
STAMFORD BAFFLE MC KINNEY BAFFLE
Other Clarifier Baffles
Clarifier Short CircuitingClarifier Short Circuiting
• Missing or poor effluent baffling
• Uneven effluent weirs
• Plant growth or thrash in effluent weirs
• Temperature stratification between influent & clarifier water temperatures.
ClarifierVariations
Rectangular Tank
Circular Sludge Collection and Skimming
“Squirqular” Clarifier
Clarifier VariationsClarifier Variations
Peripheral FeedPeripheral Discharge
Clarifier VariationsClarifier Variations
Peripheral Feed
Center Discharge
Clarifier VariationsClarifier Variations
Radial Discharge Peripheral Feed
Clarifier VariationsClarifier Variations
Tow Bro Clarifier
Clarifier VariationsClarifier Variations
Spiral Sludge Collector
Clarifier VariationsClarifier Variations
Telescoping Valves for RAS Return
Clarifier VariationsClarifier Variations
Many OthersMany Others
Each Designed to Address Particular Concern
Clarifier VariationsClarifier Variations
Drive MechanismLubrication (Manufacturers Specs.)
Observe Proper Operation (2/Day)
Clarifier OperationClarifier Operation
Routine Inspection & Maintenance
Sludge Judge Daily (Each Shift)
Clarifier OperationClarifier Operation
Rectangular ClarifiersSludge Collection System
Operating SmoothlyFloating SludgeFrequent Shear Pin or Breaker Failure
Clarifier OperationClarifier Operation
Circular ClarifiersSkimmer/Sludge Collector
Operating SmoothlyScum Trough Plugged
CleaningWeirs – Launder - Center Well
Clarifier OperationClarifier Operation
TheHardWay
TheEasyWay
Clarifier OperationClarifier Operation
Clarifier OperationClarifier Operation
Clarifier OperationClarifier Operation
Limit Growth ?
Clarifier OperationClarifier Operation
Limit Growth ?
Covers Block Sunlight Limits Algae Growth
Clarifier OperationClarifier Operation
Limit Growth ?
Covers Block Sunlight Limits Algae Growth
Provides Cold Weather Protection
Clarifier OperationClarifier Operation
Monitoring for Short Circuiting
Visual Observation
Flow Over Weir
Solids Over Weir
Dye Testing
Clarifier OperationClarifier Operation
Routine Inspection & Maintenance
Sludge Judge Daily (Each Shift)
Cleaning
Monitoring for Short Circuiting
Also IncludesCalculating and Monitoring Loading
Clarifier OperationClarifier Operation
Detention TimeSurface Overflow Rate
Weir Overflow RateSolids Loading Rate
CLARIFIERSCLARIFIERS
Prepared ByMichigan Department of Environmental Quality
Operator Training and Certification Unit