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CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit.

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Presentation on theme: "CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit."— Presentation transcript:

1 CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit

2 Provide Quiescent Area Separation of Solids Floatable Settleable Clarifiers Sedimentation Basins Settling Tanks CLARIFIERS

3 Clarifiers Efficiency of Solids Removal Related To: 1. Characteristics of the Solids 2. Characteristics of the Water 3. Characteristics of the Clarifier

4 Stoke’s Law 2(p - p o )g 9n (d/2) 2 VF = VF= Fall Velocity (p - p o )= Density difference between particle and water n= viscosity of water g= gravitational acceleration constant d= diameter of the particle

5 Stoke’s Law VF= Fall Velocity (p - p o )= Density difference between particle and water n= viscosity of water g= gravitational acceleration constant d= diameter of the particle Forget the Formula Remember the Removal Efficiency Depends on Several Factors

6 Particle Size versus Settling Time Particle Size mm Order of SizeTime to Settle 1.0Coarse Sand3 Seconds 0.1Fine Sand38 Seconds 0.01Silt33 Minutes 0.001Bacteria55 Hours Colloidal230 Days Colloidal6.3 Years

7 Clarifiers Efficiency of Solids Removal Related To: 1. Characteristics of the Solids 2. Characteristics of the Water 3. Characteristics of the Clarifier

8 Stoke’s Law VF= Fall Velocity (p - p o )= Density difference between particle and water n= viscosity of water g= gravitational acceleration constant d= diameter of the particle Forget the Formula Remember the Removal Efficiency Depends on Several Factors

9 Warm Water Less Dense Less Viscous Solids Settle More Readily in Warm Water Than in Cold Water Cold Water More Dense More Viscous Warm Water - Greater Efficiency of Clarification Settling Rate Cool Water- Less Efficiency of Clarification

10 Clarifiers Efficiency of Solids Removal Related To: 1. Characteristics of the Solids 2. Characteristics of the Water 3. Characteristics of the Clarifier

11 Clarifiers Efficiency of Solids Removal Related To: 3. Characteristics of the Clarifier Surface Area Depth Hydraulic Loading Solids Loading

12 Clarifiers Efficiency of Solids Removal Related To: 3. Characteristics of the Clarifier Surface Area Depth Hydraulic Loading Solids Loading Design Operation Maintenance

13 Clarifiers Efficiency of Solids Removal Related To: 3. Characteristics of the Clarifier Flow Characteristics in the Clarifier Flow Must be Dispersed Evenly Throughout

14 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 Circuiting

15 Missing or poor influent baffling Causes

16 Clarifier Short Circuiting Missing or poor influent baffling Causes

17 Clarifier Short Circuiting Missing or poor influent baffling Causes

18 Clarifier Short Circuiting Uneven effluent weirs Plant growth or thrash in effluent weirs Causes

19 Clarifier Short Circuiting Temperature stratification between influent & clarifier water temperatures. Causes

20 Clarifier Short Circuiting Monitoring for Short Circuiting Visual Observation Flow Over Weir Solids Over Weir

21 Clarifier Short Circuiting Monitoring for Short Circuiting Dye Testing

22 Higher Flow (Horizontal Velocity) in One Part of Tank Density Currents Clarifier Short Circuiting

23 Missing or poor influent baffling Uneven effluent weirs Plant growth or thrash in effluent weirs Temperature stratification between influent & clarifier water temperatures. Causes

24 Clarifiers Efficiency of Solids Removal Related To: 1. Characteristics of the Solids 2. Characteristics of the Water 3. Characteristics of the Clarifier

25 Clarifiers Types of Clarifiers Inclined Plate (Lamella) Rectangular Circular

26 Inclined Plate (Lamella)

27 Overflow Box Clarifier Influent Sludge Discharge Clarifier Effluent Sludge Hopper Flocculation Tank Flash Mix Tank Coagulant Feed Feed Box Discharge Flumes Distribution Orifice Inclined Plates Types of Clarifiers – Inclined Plate (Lamella)

28

29 Increased settling efficiency due to increased surface area Smaller Area Needed for Installation Types of Clarifiers – Inclined Plate (Lamella)

30 Increased settling efficiency due to increased surface area Smaller Area Needed for Installation Types of Clarifiers – Inclined Plate (Lamella)

31 Seldom Used With Organic Wastes Biological Growths Reduce Efficiency Mostly Industrial Applications Types of Clarifiers – Inclined Plate (Lamella)

32 Rectangular Clarifiers

33 Effluent Launder Effluent Weir Scum Trough Flights Drive Unit Drive Chain Drive Gear Idler Sprockets Sludge Withdrawal Pipe Sludge Trough Inlet Baffle Inlet Types of Clarifiers – Rectangular

34 Inlet Baffle Inlet Types of Clarifiers – Rectangular

35 Influent baffling Types of Clarifiers – Rectangular

36 Floatable Settleable

37 Effluent Launder Effluent Weir Types of Clarifiers – Rectangular Effluent

38 Types of Clarifiers – Rectangular Floatable Settleable

39 Rails Types of Clarifiers – Rectangular Solids Removal Mechanism

40 Types of Clarifiers – Rectangular Drive Chain Drive Unit Drive Gear Idler Sprockets

41 Types of Clarifiers – Rectangular Flights

42 Rails Types of Clarifiers – Rectangular Flights

43 Wear Shoes Rails Types of Clarifiers – Rectangular

44 Wear ShoesRails Types of Clarifiers – Rectangular Prevent Wear on the Flights Where They Contact the Rails Transfer Wear to the Shoe Instead of the Flights

45 Types of Clarifiers – Rectangular Flights Sludge Sludge Withdrawal Pipe Sludge Trough

46 Types of Clarifiers – Rectangular

47 Flights Scum Scum Removal Scum Trough

48 Types of Clarifiers – Rectangular Scum Removal

49 Types of Clarifiers – Rectangular Scum Removal

50 Effluent Launder Effluent Weir Types of Clarifiers – Rectangular Effluent

51 Types of Clarifiers – Rectangular Effluent Weir – “V Notch” Flow = Velocity X Area

52 As Flow Increases, Area Increases And As Area Increases, Velocity Decreases Types of Clarifiers – Rectangular Flow = Velocity X Area Effluent Weir – “V Notch”

53 Types of Clarifiers – Rectangular Effluent Weir – “V Notch” Helps Keep Velocity Constant Reduces Solids Build-up Behind Weir

54 Types of Clarifiers – Rectangular Single Weir Finger Weirs Effluent Weirs

55 Types of Clarifiers – Rectangular Effluent Weirs

56 Effluent Launder Effluent Weir Scum Trough Flights Drive Unit Drive Chain Drive Gear Idler Sprockets Sludge Withdrawal Pipe Sludge Trough Inlet Baffle Inlet Types of Clarifiers – Rectangular

57 Monitor for Short Circuiting Visual Observation Flow Over Weir Solids Over Weir Dye Testing Secondary Rectangular Clarifiers – Most Important Consider Baffles

58 Circular Clarifiers

59 Circular Clarifier

60 Influent typically enters the basin from the center rather than from one end.

61 Circular Clarifier Influent Influent typically enters the basin from the center rather than from one end.

62 Circular Clarifier Influent A Circular Baffle Directs Flow Center Baffle

63 Circular Clarifier A Circular Baffle Directs Flow

64 Circular Clarifier Influent Solids Settle Scraped to Sump Removed by Pumping Center Baffle Sludge Sump Sludge Plow

65 Circular Clarifier Solids Settle Scraped to Sump Removed by Pumping

66 Circular Clarifier Solids Settle Scraped to Sump Removed by Pumping

67 Circular Clarifier Influent Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum Drive Unit Skimmer Arm Scum Baffle

68 Circular Clarifier Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum

69 Circular Clarifier Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum

70 Circular Clarifier Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum

71 Circular Clarifier Drive Mechanism Also Drives Skimmer Arm to Remove Floating Scum

72 Circular Clarifier Influent The Water Flows to the Effluent Weir Around the Circumference of the Clarifier Center Baffle Effluent Weir Sludge Sump Sludge Plow

73 Circular Clarifier Outlet Effluent Launder Effluent Weir Scum Baffle

74 1 2 3 Outer Wall Inner Wall Suspended In Clarifier The Launder and Weir May Be

75 Effluent Launder/Weir Inside Clarifier (#2) Can Create Water Current Loss of solids over weir. Baffles used to redirect & slow water currents.

76 STAMFORD BAFFLEMC KINNEY BAFFLE Other Clarifier Baffles

77 Clarifier Short Circuiting Missing or poor effluent baffling Uneven effluent weirs Plant growth or thrash in effluent weirs Temperature stratification between influent & clarifier water temperatures.

78 Clarifier Variations

79 Rectangular Tank Circular Sludge Collection and Skimming “Squirqular” Clarifier Clarifier Variations

80 Peripheral Feed Peripheral Discharge Clarifier Variations

81 Peripheral Feed Center Discharge Clarifier Variations

82 Radial Discharge Peripheral Feed Clarifier Variations

83 Tow Bro Clarifier Clarifier Variations

84 Spiral Sludge Collector Clarifier Variations

85 Telescoping Valves for RAS Return Clarifier Variations

86 Many Others Each Designed to Address Particular Concern Clarifier Variations

87 Drive Mechanism Lubrication (Manufacturers Specs.) Observe Proper Operation (2/Day) Clarifier Operation Routine Inspection & Maintenance

88 Sludge Judge Daily (Each Shift) Clarifier Operation

89 Rectangular Clarifiers Sludge Collection System Operating Smoothly Floating Sludge Frequent Shear Pin or Breaker Failure Clarifier Operation Circular Clarifiers Skimmer/Sludge Collector Operating Smoothly Scum Trough Plugged

90 Cleaning Weirs – Launder - Center Well Clarifier Operation

91 The Hard Way The Easy Way Clarifier Operation

92

93 Limit Growth ?

94 Clarifier Operation Limit Growth ? Covers Block Sunlight Limits Algae Growth

95 Clarifier Operation Limit Growth ? Covers Block Sunlight Limits Algae Growth Provides Cold Weather Protection

96 Clarifier Operation Monitoring for Short Circuiting Visual Observation Flow Over Weir Solids Over Weir Dye Testing

97 Clarifier Operation Routine Inspection & Maintenance Sludge Judge Daily (Each Shift) Cleaning Monitoring for Short Circuiting

98 Also Includes Calculating and Monitoring Loading Clarifier Operation Detention Time Surface Overflow Rate Weir Overflow Rate Solids Loading Rate

99 CLARIFIERS Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit


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