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Vortex Grit Removal
Presented By:Presented By:Isaiah LaRueIsaiah LaRue
Smith & Loveless Inc.Smith & Loveless Inc.
[email protected] @smithandloveless.com
What is Grit?What is Grit?What is Grit?What is Grit?
INORGANICSSand Cinders
Soil Coal
Glass Stone
Specific Gravity of 2.65 & aboveSpecific Gravity of 2.65 & above
What is Specific Gravity?
• Correlates to a particle’s settling velocity, which measures the speed or time a particle will settle in the water.
GRIT SIZES
Sand 0.1 mm to 2.0 mm
Soil 0.002 mm to 0.1 mm
Stone Varies
Glass Varies
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Variables Influencing Quantity of Grit
Variables Influencing Quantity of GritQuantity of GritQuantity of Grit
Variables Influencing Quantity of Grit
Variables Influencing Quantity of Grit
• Type of Collection System– Combined
Separate
• Type of Collection System– Combined
Separate– Separate
• Condition of Sewer System
• Geographic Location
– Separate
• Condition of Sewer System
• Geographic Location
Rule of ThumbRule of Thumb
SEPARATE SEWERSAverage 2 to 4 ft3 per MGDPeak 8 ft3 per MGDPeak 8 ft per MGDCOMBINED SEWERSAverage 8 to 20 ft3 per MGDPeak 40 ft3 per MGD
Grit System LocationGrit System LocationGrit System LocationGrit System Location
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Grit System LocationGrit System Location
Bar ScreenBar Screen Grit RemovalGrit Removal AerationAeration
Purpose of G it R l?
Purpose of G it R l?Grit Removal?Grit Removal?
Grit Removal Prevents:Grit Removal Prevents:
• Extra Maintenance for Excessive Wear of Mechanical Equipment
• Extra Maintenance for Excessive Wear of Mechanical Equipment
• Clogged Channels and Pipes
• Accumulation of Grit in Digesters, Aeration Basins and Clarifiers
• Clogged Channels and Pipes
• Accumulation of Grit in Digesters, Aeration Basins and Clarifiers
Grit Removal System C t
Grit Removal System C tComponentsComponents
Grit Removal System Components
Grit Removal System Components
• Grit Removal Chamber
• Grit Slurry Conveyance (Pumping)
• Grit Removal Chamber
• Grit Slurry Conveyance (Pumping)• Grit Slurry Conveyance (Pumping)
• Grit Slurry Concentration
• Grit Cleaning, Washing, Dewatering
• Grit Disposal
• Grit Slurry Conveyance (Pumping)
• Grit Slurry Concentration
• Grit Cleaning, Washing, Dewatering
• Grit Disposal
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Vortex Grit ChambersVortex Grit ChambersVortex Grit ChambersVortex Grit Chambers
1953 Design1953 Design
Current DesignCurrent Design
Advantages of Flat BottomAdvantages of Flat Bottom•Flat floor uses forced hydraulic, vortex movement - not gravity•Flat floor uses forced hydraulic, vortex movement - not gravity
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270 Degree Layout270 Degree Layout
Low Flows Impact Vortex Grit Chambers
• Never meeting future design points
• Local areas working on solving I&I problems in the collection system.
Grit Removal System C t
Grit Removal System C tComponentsComponents
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Grit PumpingGrit Pumpingp gp g
SONIC START™
Replaces Electrode
Electrode’s Cleaning Issues
Replaces Electrode
Electrode’s Cleaning Issues
6 x Model 70.0
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Grit Piping GuidelinesGrit Piping GuidelinesGuidelinesGuidelines
Minimize Grit PipingMinimize Grit Piping
The More Complicated the Grit Piping, the Greater Likelihood of Grit Handling
P bl
The More Complicated the Grit Piping, the Greater Likelihood of Grit Handling
P blProblemsProblems
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Grit Piping RulesGrit Piping Rules
• Suction Piping Should be Kept to a Minimum (Less than 10’)
• Suction Piping Should be Kept to a Minimum (Less than 10’)
• Never Use Check Valves, instead use Pinch Valves
• Use Good Screening Equipment Ahead of Grit Process (3/4” max. opening)
• Never Use Check Valves, instead use Pinch Valves
• Use Good Screening Equipment Ahead of Grit Process (3/4” max. opening)
Grit Piping RulesGrit Piping Rules
• Remove All Grit From Basin Every Cycle
• Use Water Flush Into Suction Line
• Remove All Grit From Basin Every Cycle
• Use Water Flush Into Suction Line• Use Water Flush Into Suction Line (Flooded Suction Applications-Air Not Recommended)
• May Run Flush Water While Pumping (Flooded Suction Applications-Air Not Recommended)
• Use Water Flush Into Suction Line (Flooded Suction Applications-Air Not Recommended)
• May Run Flush Water While Pumping (Flooded Suction Applications-Air Not Recommended)
Grit Piping RulesGrit Piping Rules
• Use Dedicated Suction & Discharge Lines for Dual Pumps
• Use Dedicated Suction & Discharge Lines for Dual Pumps
• Eliminate Unnecessary Elbows
• Use 45o Elbows if Necessary
• Eliminate Unnecessary Elbows
• Use 45o Elbows if Necessary
Grit Dewatering Equipment
Grit Dewatering EquipmentEquipmentEquipment
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Custom-Engineered and Patented Screw to Further Clean the Grit Through Additional Agitation
Intense Flushing with Water Aids in Organic Separation
Custom-Engineered and Patented Screw to Further Clean the Grit Through Additional Agitation
Intense Flushing with Water Aids in Organic Separation
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22
p
High Air Infusion Aids in Organic Separation
p
High Air Infusion Aids in Organic Separation33
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Growing Landfill Restrictions.
Growing Concerns About Odor & Disease Conveying Insects
Why a Grit Washer?
Conveying Insects.
More Stringent Regulations, particularly internationally and we perceive those to be heading to the U.S.
• Grit retention of 95%, down to 140 mesh particle size
• Less than or equal to 5% putrescible organic
• Grit retention of 95%, down to 140 mesh particle size
• Less than or equal to 5% putrescible organic
Specifications Specifications
Less than or equal to 5% putrescible organic material in washed grit
• Less than 10% water content in washed grit -Passes paint filter test
Less than or equal to 5% putrescible organic material in washed grit
• Less than 10% water content in washed grit -Passes paint filter test
Reprinted with the permission of Smith & Loveless, Inc. © 2007-2010.
Issues Impacting Your Grit Chambers
• Older design units that don’t have the newest innovations
Alexandria, LA -side-by-side units,
1 with, 1 without FLUIDIZER
Issues Impacting Your Grit Chambers
• Not operating correctly due to missing parts
Does the unit still have the hopper plates inthe hopper plates in place?
Is the pinch valve set correctly?
Are the Axial Flow Propellers still intact?
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Issues Impacting Your Grit Chambers
• Low Flows - Never met future design points, local areas working on I&I
• Low flows do not provide enough velocity to carry grit into chamber
• After I&I work, installations going from average daily flow of 12 MGD, to 8 MGD
Submerged Weir
At 70 MGD, H1 = 5 ft, Vel = 3.5 ft/sec
At 29 MGD, H1 = 3.3 ft, Vel = 2.3 ft/sec
At 13 MGD, H1 = 2.7 ft, Vel = 1.2 ft/sec
At 7 MGD, H1 = 2 ft, Vel = 0.9 ft/sec
H1 = inlet channel water elevation
At 70 MGD, H1 = 5 ft, Vel = 3.5 ft/sec
At 29 MGD, H1 = 3.3 ft, Vel = 2.3 ft/sec
At 13 MGD, H1 = 2.7 ft, Vel = 1.2 ft/sec
At 7 MGD, H1 = 2 ft, Vel = 0.9 ft/sec
H1 = inlet channel water elevation
V-FORCE BAFFLE
At 70 MGD, H1 = 5 ft, Vel = 3.5 ft/sec
At 29 MGD, H1 = 2.8 ft, Vel = 2.6 ft/sec
At 13 MGD, H1 = 1.6 ft, Vel = 2 ft/sec
At 7 MGD, H1 = 1.1 ft, Vel = 1.6 ft/sec
H1 = inlet channel water elevation
At 70 MGD, H1 = 5 ft, Vel = 3.5 ft/sec
At 29 MGD, H1 = 2.8 ft, Vel = 2.6 ft/sec
At 13 MGD, H1 = 1.6 ft, Vel = 2 ft/sec
At 7 MGD, H1 = 1.1 ft, Vel = 1.6 ft/sec
H1 = inlet channel water elevation
Grit Testing
Why is Grit Testing Knowledge Important?
• The influx of new testing methodologies are yieldingThe influx of new testing methodologies are yielding significant differences in results
• Established performance grit testing protocols have been practice for decades
T d t i th t l ti f b
Purpose of Grit Removal Testing and Grit Characterization
•To determine the actual operating performance by testing inlet and outlet
•Knowing the volume of individual grit particle sizes (50, 70, 100, & 140 mesh)
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Testing Parameters
• Tests were performed on the same vortex grit tank
• Dry weather conditions
• Samples taken at the same location in the flume
• Each sample was taken with the unit running at design flow
Cross-Channel Sampling (CCS)
Side by Side Testing
Photos taken by S&L during a grit test witnessed bySmith & Loveless and performed by Grit Solutions
Vertical Integrated
Sampling (VIS)
Sampling Probe Review
CROSS CHANNEL SAMPLING PROBE
DIAGRAM
VERTICAL INTEGRATED
SAMPLER DIAGRAM
Testing Equipment and Number of Samples
CCS VELOCITY PROFILE DIAGRAM
VIS VELOCITY PROFILE DIAGRAM
Results Results
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Results
THANK YOUTHANK YOU