Vortex Grit Removal

Presented By:Presented By:Isaiah LaRueIsaiah LaRue

Smith & Loveless Inc.Smith & Loveless Inc.

ilarue@smithandloveless.comilarue@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

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

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

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

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

Grit PumpingGrit Pumpingp gp g

SONIC START™

Replaces Electrode

Electrode’s Cleaning Issues

Replaces Electrode

Electrode’s Cleaning Issues

6 x Model 70.0

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

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

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

11

22

p

High Air Infusion Aids in Organic Separation

p

High Air Infusion Aids in Organic Separation33

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?

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)

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

Results

THANK YOUTHANK YOU